Publications by authors named "Dennis Francis"

59 Publications

Molecular Analysis of the E2F/DP Gene Family of and Involvement of the DcE2F1 Factor in Cell Proliferation.

Front Plant Sci 2021 12;12:652570. Epub 2021 Mar 12.

Department of Agricultural Sciences, University of Sassari, Sassari, Italy.

E2F transcription factors are key components of the RB/E2F pathway that, through the action of cyclin-dependent kinases, regulates cell cycle progression in both plants and animals. Moreover, plant and animal E2Fs have also been shown to regulate other cellular functions in addition to cell proliferation. Based on structural and functional features, they can be divided into different classes that have been shown to act as activators or repressors of E2F-dependent genes. Among the first plant E2F factors to be reported, we previously described DcE2F1, an activating E2F which is expressed in cycling carrot () cells. In this study, we describe the identification of the additional members of the E2F/DP family of , which includes four typical E2Fs, three atypical E2F/DEL genes, and three related DP genes. Expression analyses of the carrot and genes reveal distinctive patterns and suggest that the functions of some of them are not necessarily linked to cell proliferation. DcE2F1 was previously shown to transactivate an E2F-responsive promoter in transient assays but the functional role of this protein was not defined. Sequence comparisons indicate that DcE2F1 could be an ortholog of the AtE2FA factor of . Moreover, ectopic expression of the cDNA in transgenic Arabidopsis plants is able to upregulate and promotes cell proliferation, giving rise to polycotyly with low frequency, effects that are highly similar to those observed when over-expressing . These results indicate that DcE2F1 is involved in the control of cell proliferation and plays important roles in the regulation of embryo and plant development.
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http://dx.doi.org/10.3389/fpls.2021.652570DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7994507PMC
March 2021

Understanding Pediatric Norovirus Epidemiology: A Decade of Study among Ghanaian Children.

Viruses 2020 11 18;12(11). Epub 2020 Nov 18.

Department of Electron Microscopy and Histopathology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Accra 00233, Ghana.

Understanding the epidemiology of human norovirus infection in children within Ghana and the entire sub-Saharan African region, where future norovirus vaccines would have the greatest impact, is essential. We analyzed 1337 diarrheic stool samples collected from children <5 years from January 2008 to December 2017 and found 485 (36.2%) shedding the virus. GII.4 (54.1%), GII.3 (7.7%), GII.6 (5.3%), GII.17 (4.7%), and GII.5 (4.7%) were the most common norovirus genotypes. Although norovirus GII.4 remained the predominant capsid genotype throughout the study period, an increase in GII.6 and GII.3 capsid genotypes was observed in 2013 and 2014, respectively. The severity of clinical illness in children infected with GII.4 norovirus strains was similar to illness caused by non-GII.4 strains. Since the epidemiology of norovirus changes rapidly, establishment of systematic surveillance within sentinel sites across the country would enhance the monitoring of circulating norovirus strains and allow continuous understanding of norovirus infection in Ghana.
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http://dx.doi.org/10.3390/v12111321DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7698731PMC
November 2020

Whole Genome Analysis of South African G1P[8] Rotavirus Strains Before and After Vaccine Introduction Over A Period of 14 Years.

Vaccines (Basel) 2020 Oct 14;8(4). Epub 2020 Oct 14.

Next Generation Sequencing Unit and Division of Virology, Faculty of Health Sciences, University of the Free State, Bloemfontein 9300, South Africa.

Rotavirus G1P[8] strains account for more than half of the group A rotavirus (RVA) infections in children under five years of age, globally. A total of 103 stool samples previously characterized as G1P[8] and collected seven years before and seven years after introducing the Rotarix vaccine in South Africa were processed for whole-genome sequencing. All the strains analyzed had a Wa-like constellation (G1-P[8]-I1-R1-C1-M1-A1-N1-T1-E1-H1). South African pre- and post-vaccine G1 strains were clustered in G1 lineage-I and II while the majority (84.2%) of the P[8] strains were grouped in P[8] lineage-III. Several amino acid sites across ten gene segments with the exception of VP7 were under positive selective pressure. Except for the N147D substitution in the antigenic site of eight post-vaccine G1 strains when compared to both Rotarix and pre-vaccine strains, most of the amino acid substitutions in the antigenic regions of post-vaccine G1P[8] strains were already present during the pre-vaccine period. Therefore, Rotarix did not appear to have an impact on the amino acid differences in the antigenic regions of South African post-vaccine G1P[8] strains. However, continued whole-genome surveillance of RVA strains to decipher genetic changes in the post-vaccine period remains imperative.
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http://dx.doi.org/10.3390/vaccines8040609DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7712154PMC
October 2020

Report of the 1st African Enteric Viruses Genome Initiative (AEVGI) Data and Bioinformatics Workshop on whole-genome analysis of some African rotavirus strains held in Bloemfontein, South Africa.

Vaccine 2020 07 17;38(34):5402-5407. Epub 2020 Jun 17.

Centre for Global Vaccine Research, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Ronald Ross Building, 8 West Derby Street, Liverpool, L69 7BE, UK; Malawi-Liverpool-Wellcome Trust Clinical Research Programme/Department of Medical Laboratory Sciences, College of Medicine, University of Malawi, Blantyre, Malawi.

The University of the Free State - Next Generation Sequencing (NGS) Unit, Bloemfontein, South Africa, hosted a data and bioinformatics workshop from 19 to 22 June 2018. The workshop was coordinated by the African Enteric Viruses Genome Initiative (AEVGI) with support from the Bill & Melinda Gates Foundation. The event introduced technologies in NGS and data analysis with focus on the rotavirus (RV) genome. The workshop fostered interactions and networking between professionals, scientific experts, technicians and students. The courses provided an overview of RV diarrhoea and its burden in Africa, while highlighting the key resources and methodologies in NGS and advanced bioinformatics in deciphering vaccine impact. It was concluded that, despite the reported significant decline in RV associated-diarrhoea mortality and morbidity in Africa due to RV vaccine impact, the need for continuous surveillance and genomic characterization to better understand the ever-changing dynamics of RV strains is imperative.
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http://dx.doi.org/10.1016/j.vaccine.2020.06.010DOI Listing
July 2020

Uncovering the First Atypical DS-1-like G1P[8] Rotavirus Strains That Circulated during Pre-Rotavirus Vaccine Introduction Era in South Africa.

Pathogens 2020 May 20;9(5). Epub 2020 May 20.

Next Generation Sequencing Unit, Division of Virology, Faculty of Health Sciences, University of the Free State, Bloemfontein 9300, South Africa.

Emergence of DS-1-like G1P[8] group A rotavirus (RVA) strains during post-rotavirus vaccination period has recently been reported in several countries. This study demonstrates, for the first time, rare atypical DS-1-like G1P[8] RVA strains that circulated in 2008 during pre-vaccine era in South Africa. Rotavirus positive samples were subjected to whole-genome sequencing. Two G1P[8] strains (RVA/Human-wt/ZAF/UFS-NGS-MRC-DPRU1971/2008/G1P[8] and RVA/Human-wt/ZAF/UFS-NGS-MRC-DPRU1973/2008/G1P[8]) possessed a DS-1-like genome constellation background (I2-R2-C2-M2-A2-N2-T2-E2-H2). The outer VP4 and VP7 capsid genes of the two South African G1P[8] strains had the highest nucleotide (amino acid) nt (aa) identities of 99.6-99.9% (99.1-100%) with the VP4 and the VP7 genes of a locally circulating South African strain, RVA/Human-wt/ZAF/MRC-DPRU1039/2008/G1P[8]. All the internal backbone genes (VP1-VP3, VP6, and NSP1-NSP5) had the highest nt (aa) identities with cognate internal genes of another locally circulating South African strain, RVA/Human-wt/ZAF/MRC-DPRU2344/2008/G2P[6]. The two study strains emerged through reassortment mechanism involving locally circulating South African strains, as they were distinctly unrelated to other reported atypical G1P[8] strains. The identification of these G1P[8] double-gene reassortants during the pre-vaccination period strongly supports natural RVA evolutionary mechanisms of the RVA genome. There is a need to maintain long-term whole-genome surveillance to monitor such atypical strains.
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http://dx.doi.org/10.3390/pathogens9050391DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7281366PMC
May 2020

Next-generation sequencing of a human-animal reassortant G6P[14] rotavirus A strain from a child hospitalized with diarrhoea.

Arch Virol 2020 Apr 10;165(4):1003-1005. Epub 2020 Feb 10.

Department of Electron Microscopy and Histopathology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Accra, Ghana.

We previously reported the VP4 and the VP7 genotypes of the first G6P[14] rotavirus strain (RVA/Human-wt/GHA/M0084/2010/G6P[14]) from the stool of an infant with diarrhoea in Ghana. In the current study, we obtained the complete genome sequences using Illumina MiSeq next-generation sequencing to enable us to determine the host species origin of the genes by phylogenetic analysis. The genotype constellation was G6-P[14]-I2-R2-C2-M2-A11-N2-T6-E2-H3. Phylogenetic analysis showed that M0084 was a reassortant strain from RVAs of both artiodactyl and human host species origin. The level of sequence identity of the individual genes of M0084 to other sequences in the GenBank ranged from 95.2 to 99.5%; however, there was no single strain from the GenBank database with a complete genome sequence that was highly similar to that of M0084. To help trace the source of such unique gene pools being introduced into human RVAs, it will be useful to examine RVA sequences from potential reservoirs such as sheep and goats, which are common domestic animals in this locality.
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http://dx.doi.org/10.1007/s00705-020-04543-4DOI Listing
April 2020

Queering the (Ab)Normalization of Gender, (Hetero)Sexuality and Schooling in South Africa.

Authors:
Dennis Francis

J Homosex 2019 Dec 13:1-20. Epub 2019 Dec 13.

Department of Sociology and Social Anthropology, Stellenbosch University, Stellenbosch, South Africa.

Schools are places where youth do work on the construction of their sexual identities which is intimately connected with issues around gender. Using one-on-one in-depth interviews, this article addresses how queer youth navigate dominant understandings of gender and sexuality in the context of their identity and practice. Cognizant of how gender remains a significant force in organizing social relations in schools, the youth parody and abnormalize heteronormativity calling into question the fragility of hegemonic heterosexuality. Moreover, the findings demonstrate that despite evidence that associates schooling with social exclusion, the queer youth's accounts highlight, strikingly, that queer identity and inclusion are not necessarily separate storylines. Offering an alternative view of the schooling experiences of queer youth, the paper motivates that within exclusion, in a matter of speaking with all its unduly assemblages, is inclusion.
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http://dx.doi.org/10.1080/00918369.2019.1701337DOI Listing
December 2019

Distribution of rotavirus genotypes in the postvaccine introduction era in Ashaiman, Greater Accra Region, Ghana, 2014-2016.

J Med Virol 2019 11 23;91(11):2025-2028. Epub 2019 Jul 23.

West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), Department of Biochemistry, Cell and Molecular Biology, University of Ghana, Accra, Ghana.

Group A Rotaviruses (RVAs) are the most important etiological agents of acute gastroenteritis (AGE) in children less than 5 years of age. Mortality resulting from RVA gastroenteritis is higher in developing countries than in developed ones, causing a huge public health burden in global regions like Africa and South-East Asia. This study reports RVA genotypes detected in Ashaiman, Greater Accra Region, Ghana, in the postvaccine introduction era for the period 2014-2016. Stool samples were collected from children less than 5 years of age who visited Ashaiman Polyclinic with AGE from November 2014 to May 2015 and from December 2015 to June 2016. The samples were tested by enzyme immunoassay (EIA), and one-step multiplex reverse transcription polymerase chain reaction was performed on the EIA positive samples for gel-based binomial genotyping. Of the 369 stool samples collected from children with AGE, 145 (39%) tested positive by EIA. Five VP7 (G1, G3, G9, G10, and G12) and three VP4 (P[4], P[6] and P[8]) genotypes were detected. Eight G/P combinations were identified of which, G3P[6], G12P[8], G1P[8], and G9P[4] were the most prevalent and responsible for 93 (68%) of the AGE cases, and seven mixed-types were detected which represented 8% of the RVA cases. High prevalence, diversity, and mixed-types of RVAs were detected from Ashaiman with the emergence of unusual genotypes.
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http://dx.doi.org/10.1002/jmv.25542DOI Listing
November 2019

Nuclear Migration: An Indicator of Plant Salinity Tolerance .

Front Plant Sci 2019 12;10:783. Epub 2019 Jun 12.

Agroécologie, AgroSup Dijon, INRA, Université Bourgogne Franche-Comté, Dijon, France.

In order to understand the mechanisms underlying acquisition of tolerance to salinity, we recently produced callus tissues of tobacco and resistant to NaCl-induced salt stress following application of a step-up recurrent selection method. The effects of salinity on cell size are known, but those on cell morphometry including cell and nuclear surface area and position of nuclei within salt stress resistant cells were never studied before. This work fills that gap, using suspension cultured cells of A17 initiated from callus, and BY-2 cell line resistant to increasing NaCl concentrations up to 150 mM NaCl. The surface area of salinity resistant cells of A17 and BY2 and their nuclei, produced by step-up recurrent selection, were reduced, and cells elongated as NaCl increased, but these parameters proved to be unreliable in explaining cell survival and growth at high NaCl. Conversely, nuclei of resistant cells migrated from the center to the periphery of the cytoplasm close to the walls. Nuclear marginalization was for the first time observed as a result of salt stress in plant cells, and could be a novel helpful morphological marker of acquisition of salinity tolerance.
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http://dx.doi.org/10.3389/fpls.2019.00783DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6582401PMC
June 2019

Genetic analysis of Ghanaian G1P[8] and G9P[8] rotavirus A strains reveals the impact of P[8] VP4 gene polymorphism on P-genotyping.

PLoS One 2019 26;14(6):e0218790. Epub 2019 Jun 26.

Department of Electron Microscopy and Histopathology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Accra, Ghana.

The World Health Organisation rotavirus surveillance networks have documented and shown eclectic geographic and temporal diversity in circulating G- and P- genotypes identified in children <5 years of age. To effectively monitor vaccine performance and effectiveness, robust molecular and phylogenetic techniques are essential to detect novel strain variants that might emerge due to vaccine pressure. This study inferred the phylogenetic history of the VP7 and VP4 genes of previously non-typeable strains and provided insight into the diversity of P[8] VP4 sequences which impacted the outcome of our routine VP4 genotyping method. Near-full-length VP7 gene and the VP8* fragment of the VP4 gene were obtained by Sanger sequencing and genotypes were determined using RotaC v2.0 web-based genotyping tool. The genotypes of the 57 rotavirus-positive samples with sufficient stool was determined. Forty-eight of the 57 (84.2%) had the P[8] specificity, of which 43 (89.6%) were characterized as P[8]a subtype and 5 (10.4%) as the rare OP354-like subtype. The VP7 gene of 27 samples were successfully sequenced and their G-genotypes confirmed as G1 (18/27) and G9 (9/27). Phylogenetic analysis of the P[8]a sequences placed them in subcluster IIIc within lineage III together with contemporary G1P[8], G3P[8], G8P[8], and G9P[8] strains detected globally from 2006-2016. The G1 VP7 sequences of the study strains formed a monophyletic cluster with African G1P[8] strains, previously detected in Ghana and Mali during the RotaTeq vaccine trial as well as Togo. The G9 VP7 sequences of the study strains formed a monophyletic cluster with contemporary African G9 sequences from neighbouring Burkina Faso within the major sub-cluster of lineage III. Mutations identified in the primer binding region of the VP8* sequence of the Ghanaian P[8]a strains may have resulted in the genotyping failure since the newly designed primer successfully genotyped the previously non-typeable P[8] strains. In summary, the G1, G9, and P[8]a sequences were highly similar to contemporary African strains at the lineage level. The study also resolved the methodological challenges of the standard genotyping techniques and highlighted the need for regular evaluation of the multiplex PCR-typing method especially in the post-vaccination era. The study further highlights the need for regions to start using sequencing data from local rotavirus strains to design and update genotyping primers.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0218790PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6594640PMC
February 2020

Expression of Arabidopsis WEE1 in tobacco induces unexpected morphological and developmental changes.

Sci Rep 2019 06 18;9(1):8695. Epub 2019 Jun 18.

Department of Experimental Plant Biology, Charles University, Faculty of Science, Viničná 5, 128 43, Praha 2, Czech Republic.

WEE1 regulates the cell cycle by inactivating cyclin dependent protein kinases (CDKs) via phosphorylation. In yeast and animal cells, CDC25 phosphatase dephosphorylates the CDK releasing cells into mitosis, but in plants, its role is less clear. Expression of fission yeast CDC25 (Spcdc25) in tobacco results in small cell size, premature flowering and increased shoot morphogenetic capacity in culture. When Arath;WEE1 is over-expressed in Arabidopsis, root apical meristem cell size increases, and morphogenetic capacity of cultured hypocotyls is reduced. However expression of Arath;WEE1 in tobacco plants resulted in precocious flowering and increased shoot morphogenesis of stem explants, and in BY2 cultures cell size was reduced. This phenotype is similar to expression of Spcdc25 and is consistent with a dominant negative effect on WEE1 action. Consistent with this putative mechanism, WEE1 protein levels fell and CDKB levels rose prematurely, coinciding with early mitosis. The phenotype is not due to sense-mediated silencing of WEE1, as overall levels of WEE1 transcript were not reduced in BY2 lines expressing Arath;WEE1. However the pattern of native WEE1 transcript accumulation through the cell cycle was altered by Arath;WEE1 expression, suggesting feedback inhibition of native WEE1 transcription.
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http://dx.doi.org/10.1038/s41598-019-45015-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6581958PMC
June 2019

Whole genome characterization and evolutionary analysis of OP354-like P[8] Rotavirus A strains isolated from Ghanaian children with diarrhoea.

PLoS One 2019 14;14(6):e0218348. Epub 2019 Jun 14.

Department of Electron Microscopy and Histopathology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana.

In 2010, the rare OP354-like P[8]b rotavirus subtype was detected in children less than 2 years old in Ghana. In this follow-up study, to provide insight into the evolutionary history of the genome of Ghanaian P[8]b strains RVA/Human-wt/GHA/GHDC949/2010/G9P[8] and RVA/Human-wt/GHA/GHM0094/2010/G9P[8] detected in an infant and a 7-month old child hospitalised for acute gastroenteritis, we sequenced the complete genome using both Sanger sequencing and Illumina MiSeq technology followed by phylogenetic analysis of the near-full length sequences. Both strains possessed the Wa-like/genotype 1 constellation G9P[8]b-I1-R1-C1-M1-A1-N1-T1-E1-H1. Sequence comparison and phylogenetic inference showed that both strains were identical at the lineage level throughout the 11 genome segments. Their VP7 sequences belonged to the major sub-lineage of the G9-lineage III whereas their VP4 sequences belonged to P[8]b cluster I. The VP7 and VP4 genes of the study strains were closely related to a Senegalese G9P[8]b strain detected in 2009. In the remaining nine genome segments, both strains consistently clustered together with Wa-like RVA strains possessing either P[8]a or P[8]b mostly of African RVA origin. The introduction of a P[8]b subtype VP4 gene into the stable Wa-like strain backbone may result in strains that might propagate easily in the human population, with a potential to become an important public health concern, especially because it is not certain if the monovalent rotavirus vaccine (Rotarix) used in Ghana will be efficacious against such strains. Our analysis of the full genomes of GHM0094 and GHDC949 adds to knowledge of the genetic make-up and evolutionary dynamics of P[8]b rotavirus strains.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0218348PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6570025PMC
February 2020

Sub-genotype phylogeny of the non-G, non-P genes of genotype 2 Rotavirus A strains.

PLoS One 2019 31;14(5):e0217422. Epub 2019 May 31.

Department of Molecular Epidemiology, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.

Recent increase in the detection of unusual G1P[8], G3P[8], G8P[8], and G9P[4] Rotavirus A (RVA) strains bearing the DS-1-like constellation of the non-G, non-P genes (hereafter referred to as the genotype 2 backbone) requires better understanding of their evolutionary relationship. However, within a genotype, there is lack of a consensus lineage designation framework and a set of common sequences that can serve as references. Phylogenetic analyses were carried out on over 8,500 RVA genotype 2 genes systematically retrieved from the rotavirus database within the NCBI Virus Variation Resource. In line with previous designations, using pairwise comparison of cogent nucleotide sequences and stringent bootstrap support, reference lineages were defined. This study proposes a lineage framework and provides a dataset ranging from 34 to 145 sequences for each genotype 2 gene for orderly lineage designation of global genotype 2 genes of RVAs detected in human and animals. The framework identified five to 31 lineages depending on the gene. The least number of lineages (five to seven) were observed in genotypes A2 (NSP1), T2 (NSP3) and H2 (NSP5) which are limited to human RVA whereas the most number of lineages (31) was observed in genotype E2 (NSP4). Sharing of the same lineage constellations of the genotype 2 backbone genes between recently-emerging, unusual G1P[8], G3P[8], G8P[8] and G9P[4] reassortants and many contemporary G2P[4] strains provided strong support to the hypothesis that unusual genotype 2 strains originated primarily from reassortment events in the recent past involving contemporary G2P[4] strains as one parent and ordinary genotype 1 strains or animal RVA strains as the other. The lineage framework with selected reference sequences will help researchers to identify the lineage to which a given genotype 2 strain belongs, and trace the evolutionary history of common and unusual genotype 2 strains in circulation.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0217422PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6544246PMC
February 2020

Rotavirus Vaccine Take in Infants Is Associated With Secretor Status.

J Infect Dis 2019 02;219(5):746-749

Division of Viral Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia.

Rotaviruses bind to enterocytes in a genotype-specific manner via histo-blood group antigens (HBGAs), which are also detectable in saliva. We evaluated antirotavirus immunoglobulin A seroconversion ('vaccine take") among 166 Ghanaian infants after 2-3 doses of G1P[8] rotavirus vaccine during a vaccine trial, by HBGA status from saliva collected at age 4.1 years. Only secretor status was associated with seroconversion: 41% seroconversion for secretors vs 13% for nonsecretors; relative risk, 3.2 (95% confidence interval, 1.2-8.1; P = .016). Neither Lewis antigen nor salivary antigen blood type was associated with seroconversion. Likelihood of "take" for any particular rotavirus vaccine may differ across populations based on HBGAs.
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http://dx.doi.org/10.1093/infdis/jiy573DOI Listing
February 2019

Identification of Amino Acid Substitutions Within the VP7 Genes of G2 Rotavirus Strains in Ghana.

Pediatr Infect Dis J 2018 11;37(11):1172-1174

From the Department of Electron Microscopy and Histopathology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Accra, Ghana.

We used the dideoxynucleotide chain termination method to determine the strains of nine non-typeable rotavirus enzyme immunoassay-positive samples, which were identified as G2. We detected nucleotide changes in the primer-binding region and amino acid substitutions within the VP7 protein of the G2 rotavirus strains. Genotyping primers need to be updated regularly.
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http://dx.doi.org/10.1097/INF.0000000000002037DOI Listing
November 2018

Toward Unravelling the Genetic Determinism of the Acquisition of Salt and Osmotic Stress Tolerance Through In Vitro Selection in Medicago truncatula.

Methods Mol Biol 2018 ;1822:291-314

Agroécologie, AgroSup Dijon, INRA, Univ. Bourgogne Franche-Comté, Dijon, France.

Changes in global climate and the nonstop increase in demographic pressure have provoked a stronger demand for agronomic resources at a time where land suitable for agriculture is becoming a rare commodity. They have also generated a number of abiotic stresses which exacerbate effects of diseases and pests and result in physiological and metabolic disorders that ultimately impact on yield when and where it is most needed. Therefore, a major scientific and agronomic challenge today is that of understanding and countering the impact of stress on yield. In this respect, in vitro biotechnology would be an efficient and feasible breeding alternative, particularly now that the genetic and genomic tools needed to unravel the mechanisms underlying the acquisition of tolerance to stress have become available. Legumes in general play a central role in a sustainable agriculture due to their capacity to symbiotically fix the atmospheric nitrogen, thereby reducing the need for fertilizers. They also produce grains that are rich in protein and thus are important as food and feed. However, they also suffer from abiotic stresses in general and osmotic stress and salinity in particular. This chapter provides a detailed overview of the methods employed for in vitro selection in the model legume Medicago truncatula for the generation of novel germplasm capable of resisting NaCl- and PEG-induced osmotic stress. We also address the understanding of the genetic determinism in the acquisition of stress resistance, which differs between NaCl and PEG. Thus, the expression of genes linked to growth (WEE1), in vitro embryogenesis (SERK), salt tolerance (SOS1) proline synthesis (P5CS), and ploidy level and cell cycle (CCS52 and WEE1) was upregulated under NaCl stress, while under PEG treatment the expression of MtWEE1 and MtCCS52 was significantly increased, but no significant differences were observed in the expression of genes MtSERK1 and MtP5CS, and MtSOS1 was downregulated. A number of morphological and physiological traits relevant to the acquisition of stress resistance were also assessed, and methods used to do so are also detailed.
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http://dx.doi.org/10.1007/978-1-4939-8633-0_19DOI Listing
March 2019

Detection of Dengue Virus among Children with Suspected Malaria, Accra, Ghana.

Emerg Infect Dis 2018 08;24(8):1544-1547

We report new molecular evidence of locally acquired dengue virus infections in Ghana. We detected dengue viral RNA among children with suspected malaria by using a multipathogen real-time PCR. Subsequent sequence analysis revealed a close relationship with dengue virus serotype 2, which was implicated in a 2016 outbreak in Burkina Faso.
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http://dx.doi.org/10.3201/eid2408.180341DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6056106PMC
August 2018

Rotavirus strain distribution in Ghana pre- and post- rotavirus vaccine introduction.

Vaccine 2018 11 20;36(47):7238-7242. Epub 2018 Jan 20.

Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana. Electronic address:

Background: Ghana introduced the monovalent rotavirus vaccine (Rotarix) into its national paediatric vaccination programme in May2012. Vaccine introduction was initiated nationwide and achieved >85% coverage within a few months. Rotavirus strain distribution pre- and post-RV vaccine introduction is reported.

Methods: Stool samples were collected from diarrhoeic children <5 years of age hospitalized between 2009 and 2016 at sentinel sites across Ghana and analyzed for the presence of group A rotavirus by enzyme immunoassay. Rotavirus strains were characterized by RT-PCR and sequencing.

Results: A total of 1363 rotavirus EIA-positive samples were subjected to molecular characterization. These were made up of 823 (60.4%) and 540 (39.6%) samples from the pre- and post-vaccine periods respectively. Rotavirus VP7 genotypes G1, G2 and G3, and VP4 genotypes P[6] and P[8] constituted more than 65% of circulating G and P types in the pre-vaccine period. The common strains detected were G1P[8] (20%), G3P[6] (9.2%) and G2P[6] (4.9%). During the post-vaccine period, G12, G1 and G10 genotypes, constituted more than 65% of the VP7 genotypes whilst P[6] and P[8] made up more than 75% of the VP4 genotypes. The predominant circulating strains were G12P[8] (26%), G10P[6] (10%) G3P[6] (8.1%) and G1P[8] (8.0%). We also observed the emergence of the unusual rotavirus strain G9P[4] during this period.

Conclusion: Rotavirus G1P[8], the major strain in circulation during the pre-vaccination era, was replaced by G12P[8] as the most predominant strain after vaccine introduction. This strain replacement could be temporary and unrelated to vaccine introduction since an increase in G12 was observed in countries yet to introduce the rotavirus vaccine in West Africa. A continuous surveillance programme in the post-vaccine era is necessary for the monitoring of circulating rotavirus strains and the detection of unusual/emerging genotypes.
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http://dx.doi.org/10.1016/j.vaccine.2018.01.010DOI Listing
November 2018

PEG Induces High Expression of the Cell Cycle Checkpoint Gene in Embryogenic Callus of : Potential Link between Cell Cycle Checkpoint Regulation and Osmotic Stress.

Front Plant Sci 2017 5;8:1479. Epub 2017 Sep 5.

Agroécologie, AgroSup Dijon, Institut National de la Recherche Agronomique (INRA), University of Bourgogne Franche-ComtéDijon, France.

Polyethylene glycol (PEG) can be used to mimic osmotic stress in plant tissue cultures to study mechanisms of tolerance. The aim of this experiment was to investigate the effects of PEG (M.W. 6000) on embryogenic callus of Leaf explants were cultured on MS medium with 2 mg L NAA and 0.5 mg L BAP for 5 months. Then, calli were transferred to the same medium further supplemented with 10% (w/v) 6000 PEG for 6 months in order to study physiological and putative molecular markers of water stress. There were no significant differences in growth rate of callus or mitotic index ± PEG although embryogenic potential of PEG treated callus was morphologically enhanced. Cells were rounder on PEG medium and cell size, nuclear size and endoreduplication increased in response to the PEG treatment. Significant increases in soluble sugar and proline accumulation occurred under PEG treatment compared with the control. Significantly, high and expression resulted from 6 months of PEG treatment with no significant differences in or expression but down regulation of S expression. The results are consistent in showing elevated expression of a cell cycle checkpoint gene, WEE1. It is likely that the cell cycle checkpoint surveillance machinery, that would include expression, is ameliorating the effects of the stress imposed by PEG.
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http://dx.doi.org/10.3389/fpls.2017.01479DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5591835PMC
September 2017

Etiology of Severe Acute Watery Diarrhea in Children in the Global Rotavirus Surveillance Network Using Quantitative Polymerase Chain Reaction.

J Infect Dis 2017 07;216(2):220-227

University of Ghana Medical School, Accra.

Background: The etiology of acute watery diarrhea remains poorly characterized, particularly after rotavirus vaccine introduction.

Methods: We performed quantitative polymerase chain reaction for multiple enteropathogens on 878 acute watery diarrheal stools sampled from 14643 episodes captured by surveillance of children <5 years of age during 2013-2014 from 16 countries. We used previously developed models of the association between pathogen quantity and diarrhea to calculate pathogen-specific weighted attributable fractions (AFs).

Results: Rotavirus remained the leading etiology (overall weighted AF, 40.3% [95% confidence interval {CI}, 37.6%-44.3%]), though the AF was substantially lower in the Americas (AF, 12.2 [95% CI, 8.9-15.6]), based on samples from a country with universal rotavirus vaccination. Norovirus GII (AF, 6.2 [95% CI, 2.8-9.2]), Cryptosporidium (AF, 5.8 [95% CI, 4.0-7.6]), Shigella (AF, 4.7 [95% CI, 2.8-6.9]), heat-stable enterotoxin-producing Escherichia coli (ST-ETEC) (AF, 4.2 [95% CI, 2.0-6.1]), and adenovirus 40/41 (AF, 4.2 [95% CI, 2.9-5.5]) were also important. In the Africa Region, the rotavirus AF declined from 54.8% (95% CI, 48.3%-61.5%) in rotavirus vaccine age-ineligible children to 20.0% (95% CI, 12.4%-30.4%) in age-eligible children.

Conclusions: Rotavirus remained the leading etiology of acute watery diarrhea despite a clear impact of rotavirus vaccine introduction. Norovirus GII, Cryptosporidium, Shigella, ST-ETEC, and adenovirus 40/41 were also important. Prospective surveillance can help identify priorities for further reducing the burden of diarrhea.
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http://dx.doi.org/10.1093/infdis/jix294DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5853801PMC
July 2017

Cell cycle arrest mediated by Cd-induced DNA damage in Arabidopsis root tips.

Ecotoxicol Environ Saf 2017 Nov 8;145:569-574. Epub 2017 Aug 8.

Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, PR China. Electronic address:

Accumulating evidence demonstrates that the aberrant expression of cell cycle regulation and DNA repair genes can result in abnormal cell proliferation and genomic instability in eukaryotic cells under different stresses. Herein, Arabidopsis thaliana (Arabidopsis) seedlings were grown hydroponically on 0.5 × MS media containing cadmium (Cd) at 0-2.5mgL for 5d of treatment. Real time quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analysis revealed that expression of DNA damage repair and cell cycle regulation genes, including BRCA1, MRE11, WEE1, CDKA;1 and PCNA1, showed an inverted U-shaped dose-response. In contrast, notably reduced expression was observed for G1-to-S transition-related genes, Histone H4, E2Fa and PCNA2; DSB end processing, GR1; G2-to-M transition-related gene, CYCB1;1; and DNA mismatch repair, MSH2, MSH6 and MLH1 genes in root tips exposed to 0.125-2.5mg/L Cd for 5d. Flow cytometry (FCM) analysis revealed significant increases of cells with a C nuclear content and with a C and C nuclear content under Cd stresses of 0.125 and 1-2.5mgL, respectively. Our results suggest that 0.125mgL Cd-induced DNA damage induced the marked G1/S arrest, leading to accelerated growth in root tips, while 1.0-2.5mgL Cd-induced DNA damage caused a notable G2/M arrest in root tips, leading to reduced growth in root tips. This may be a protective mechanism that prevents cells with damaged DNA from dividing under Cd stress.
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http://dx.doi.org/10.1016/j.ecoenv.2017.07.074DOI Listing
November 2017

Environmental impact of estrogens on human, animal and plant life: A critical review.

Environ Int 2017 Feb 29;99:107-119. Epub 2016 Dec 29.

Key Lab of Eco-restoration of Regional Contaminated Environment (Shenyang University), Ministry of Education, Shenyang 11044, PR China; Key Lab of Groundwater Resources & Environment (Jilin University), Ministry of Education, Changchun 130021, PR China. Electronic address:

Background: Since the inception of global industrialization, steroidal estrogens have become an emerging and serious concern. Worldwide, steroid estrogens including estrone, estradiol and estriol, pose serious threats to soil, plants, water resources and humans. Indeed, estrogens have gained notable attention in recent years, due to their rapidly increasing concentrations in soil and water all over the world. Concern has been expressed regarding the entry of estrogens into the human food chain which in turn relates to how plants take up and metabolism estrogens.

Objectives: In this review we explore the environmental fate of estrogens highlighting their release through effluent sources, their uptake, partitioning and physiological effects in the ecological system. We draw attention to the potential risk of intensive modern agriculture and waste disposal systems on estrogen release and their effects on human health. We also highlight their uptake and metabolism in plants.

Methods: We use MEDLINE and other search data bases for estrogens in the environment from 2005 to the present, with the majority of our sources spanning the past five years. Published acceptable daily intake of estrogens (μg/L) and predicted no effect concentrations (μg/L) are listed from published sources and used as thresholds to discuss reported levels of estrogens in the aquatic and terrestrial environments. Global levels of estrogens from river sources and from Waste Water Treatment Facilities have been mapped, together with transport pathways of estrogens in plants.

Results: Estrogens at polluting levels have been detected at sites close to waste water treatment facilities and in groundwater at various sites globally. Estrogens at pollutant levels have been linked with breast cancer in women and prostate cancer in men. Estrogens also perturb fish physiology and can affect reproductive development in both domestic and wild animals. Treatment of plants with steroid estrogen hormones or their precursors can affect root and shoot development, flowering and germination. However, estrogens can ameliorate the effects of other environmental stresses on the plant.

Conclusions: There is published evidence to establish a causal relationship between estrogens in the environment and breast cancer. However, there are serious gaps in our knowledge about estrogen levels in the environment and a call is required for a world wide effort to provide more data on many more samples sites. Of the data available, the synthetic estrogen, ethinyl estradiol, is more persistent in the environment than natural estrogens and may be a greater cause for environmental concern. Finally, we believe that there is an urgent requirement for inter-disciplinary studies of estrogens in order to better understand their ecological and environmental impact.
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http://dx.doi.org/10.1016/j.envint.2016.12.010DOI Listing
February 2017

Detection of the first G6P[14] human rotavirus strain in an infant with diarrhoea in Ghana.

Virol J 2016 11 10;13(1):183. Epub 2016 Nov 10.

Department of Electron Microscopy and Histopathology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Accra, Ghana.

Background: Rotaviruses with G6P[14] specificity are mostly isolated in cattle and have been established as a rare cause of gastroenteritis in humans. This study reports the first detection of G6P[14] rotavirus strain in Ghana from the stool of an infant during a hospital-based rotavirus surveillance study in 2010.

Methods: Viral RNA was extracted and rotavirus VP7 and VP4 genes amplified by one step RT-PCR using gene-specific primers. The DNA was purified, sequenced and genotypes determined using BLAST and RotaC v2.0. Phylogenetic tree was constructed using maximum likelihood method in MEGA v6.06 software and statistically supported by bootstrapping with 1000 replicates. Phylogenetic distances were calculated using the Kimura-2 parameter model.

Results: The study strain, GHA-M0084/2010 was characterised as G6P[14]. The VP7 gene of the Ghanaian strain clustered in G6 lineage-III together with artiodactyl and human rotavirus (HRV) strains. It exhibited the highest nucleotide (88.1 %) and amino acid (86.9 %) sequence identity with Belgian HRV strain, B10925. The VP8* fragment of the VP4 gene was closely related to HRV strains detected in France, Italy, Spain and Belgium. It exhibited the strongest nucleotide sequence identity (87.9 %) with HRV strains, PA169 and PR/1300 (Italy) and the strongest amino acid sequence identity (89.3 %) with HRV strain R2775/FRA/07 (France).

Conclusion: The study reports the first detection of G6P[14] HRV strain in an infant in Ghana. The detection of G6P[14], an unusual strain pre-vaccine introduction in Ghana, suggests a potential compromise of vaccine effectiveness and indicates the necessity for continuous surveillance in the post vaccine era.
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http://dx.doi.org/10.1186/s12985-016-0643-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5103419PMC
November 2016

Identification of OP354-like human rotavirus strains with subtype P[8]b in Ghanaian children with diarrhoea.

Virol J 2016 Apr 22;13:69. Epub 2016 Apr 22.

Department of Electron Microscopy and Histopathology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Accra, Ghana.

Background: Rotaviruses with the P[8] genotype have been associated with majority of infections. Recent improvements in molecular diagnostics have delineated the P[8] genotype into P[8]a and P[8]b subtypes. P[8]a is the previously known P[8] genotype which is common whilst P[8]b subtype also known as OP354-like strain is genetically distinct, rarely detected and reported from a few countries. In a previous study, the P-types could not be determined for 80 RVA-positive samples by conventional RT-PCR genotyping methods with the recommended pool of P-genotype specific primers used in the WHO Regional Rotavirus Reference Laboratory in Ghana. The present study employed sequence-dependent cDNA amplification method to genotype previously non-typeable P-types.

Methods: Viral RNAs were extracted and rotavirus VP4 genes amplified by one step RT-PCR using gene specific primers. PCR amplicons were purified, sequenced and sequences aligned with cognate gene sequences available in GenBank using the ClustalW algorithm. Phylogenetic analysis was performed using the Neighbour-Joining method in MEGA v6.06 software. Phylogenetic tree was statistically supported by bootstrapping with 1000 replicates, and distances calculated using the Kimura-2 parameter model.

Results: Of the 80 RVA-positive samples, 57 were successfully sequenced and characterized. Forty-eight of these were identified as P[8] strains of which 5 were characterized as the rare P[8]b subtype. Phylogenetic analysis of the VP8* fragment of the VP4 genes of these P[8]b strains revealed a close relationship with prototype OP354-like P[8]b strain and P[8]b strains of Russian and South African P[8]b origin.

Conclusion: The study highlights the importance of regularly updating the primers employed for molecular typing of rotaviruses.
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http://dx.doi.org/10.1186/s12985-016-0523-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4841057PMC
April 2016

Cadmium-induced genomic instability in Arabidopsis: Molecular toxicological biomarkers for early diagnosis of cadmium stress.

Chemosphere 2016 May 22;150:258-265. Epub 2016 Feb 22.

Key Laboratory of Pollution Ecology and Environmental Engineering, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, PR China. Electronic address:

Microsatellite instability (MSI) analysis, random-amplified polymorphic DNA (RAPD), and methylation-sensitive arbitrarily primed PCR (MSAP-PCR) are methods to evaluate the toxicity of environmental pollutants in stress-treated plants and human cancer cells. Here, we evaluate these techniques to screen for genetic and epigenetic alterations of Arabidopsis plantlets exposed to 0-5.0 mg L(-1) cadmium (Cd) for 15 d. There was a substantial increase in RAPD polymorphism of 24.5, and in genomic methylation polymorphism of 30.5-34.5 at CpG and of 14.5-20 at CHG sites under Cd stress of 5.0 mg L(-1) by RAPD and of 0.25-5.0 mg L(-1) by MSAP-PCR, respectively. However, only a tiny increase of 1.5 loci by RAPD occurred under Cd stress of 4.0 mg L(-1), and an additional high dose (8.0 mg L(-1)) resulted in one repeat by MSI analysis. MSAP-PCR detected the most significant epigenetic modifications in plantlets exposed to Cd stress, and the patterns of hypermethylation and polymorphisms were consistent with inverted U-shaped dose responses. The presence of genomic methylation polymorphism in Cd-treated seedlings, prior to the onset of RAPD polymorphism, MSI and obvious growth effects, suggests that these altered DNA methylation loci are the most sensitive biomarkers for early diagnosis and risk assessment of genotoxic effects of Cd pollution in ecotoxicology.
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http://dx.doi.org/10.1016/j.chemosphere.2016.02.042DOI Listing
May 2016

'You need to have some guts to teach': Teacher preparation and characteristics for the teaching of sexuality and HIV/AIDS education in South African schools.

SAHARA J 2015 ;12:30-8

b PhD, is an Associate Professor in Facultade de Ciencias da Educación at the University of A Coruña , A Coruña , Spain.

Using in-depth interviews, we asked sexuality educators in South Africa about their own professional preparation and what they believed were necessary educator characteristics for teaching Sexuality Education. Our findings show that our teachers taught Sexuality Education without any appropriate qualification or preparation, but because they had a lighter teaching load and had room to take on more teaching hours. Nevertheless, they all mention that 'not anybody can teach Sexuality Education'. Drawing on Shulman's taxonomy of knowledge and Freire's concept of critical consciousness, we attempt to make meaning of the teachers' responses and their relevance for the teaching of Sexuality Education.
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http://dx.doi.org/10.1080/17290376.2015.1085892DOI Listing
August 2016

Whole Genomic Analysis of Human G12P[6] and G12P[8] Rotavirus Strains that Have Emerged in Myanmar.

PLoS One 2015 4;10(5):e0124965. Epub 2015 May 4.

Department of Virology and Parasitology, Fujita Health University School of Medicine, Toyoake, Aichi, Japan.

G12 rotaviruses are emerging rotavirus strains causing severe diarrhea in infants and young children worldwide. However, the whole genomes of only a few G12 strains have been fully sequenced and analyzed. In this study, we sequenced and characterized the complete genomes of six G12 strains (RVA/Human-tc/MMR/A14/2011/G12P[8], RVA/Human-tc/MMR/A23/2011/G12P[6], RVA/Human-tc/MMR/A25/2011/G12P[8], RVA/Human-tc/MMR/P02/2011/G12P[8], RVA/Human-tc/MMR/P39/2011/G12P[8], and RVA/Human-tc/MMR/P43/2011/G12P[8]) detected in six stool samples from children with acute gastroenteritis in Myanmar. On whole genomic analysis, all six Myanmarese G12 strains were found to have a Wa-like genetic backbone: G12-P[8]-I1-R1-C1-M1-A1-N1-T1-E1-H1 for strains A14, A25, P02, P39, and P43, and G12-P[6]-I1-R1-C1-M1-A1-N1-T1-E1-H1 for strain A23. Phylogenetic analysis showed that most genes of the six strains examined in this study were genetically related to globally circulating human G1, G3, G9, and G12 strains. Of note is that the NSP4 gene of strain A23 exhibited the closest relationship with the cognate genes of human-like bovine strains as well as human strains, suggesting the occurrence of reassortment between human and bovine strains. Furthermore, strains A14, A25, P02, P39, and P43 were very closely related to one another in all the 11 gene segments, indicating derivation of the five strains from a common origin. On the other hand, strain A23 consistently formed distinct clusters as to all the 11 gene segments, indicating a distinct origin of strain A23 from that of strains A14, A25, P02, P39, and P43. To our knowledge, this is the first report on whole genome-based characterization of G12 strains that have emerged in Myanmar. Our observations will provide important insights into the evolutionary dynamics of spreading G12 rotaviruses in Asia.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0124965PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4418666PMC
April 2016

Whole genomic analysis of porcine G10P[5] rotavirus strain P343 provides evidence for bovine-to-porcine interspecies transmission.

Vet Microbiol 2014 Dec 14;174(3-4):577-583. Epub 2014 Oct 14.

Department of Virology and Parasitology, Fujita Health University School of Medicine, Toyoake, Aichi 470-1192, Japan.

Porcine group A rotavirus (RVA) strain P343 (RVA/Pig-tc/THA/P343/1991/G10P[5]) was suggested to have VP7 and VP4 genes of bovine origin. In order to obtain precise information on the exact origin and evolution of this unusual porcine strain, the remaining nine genes (VP6, VP1-3, and NSP1-5) of strain P343 were sequenced and analyzed in the present study. On whole genomic analysis, strain P343 was found to have a bovine RVA-like genotype constellation (G10-P[5]-I2-R2-C2-M2-A3-N2-T6-E2-H3) different from those of typical porcine RVA strains. Furthermore, on phylogenetic analysis, each of the 11 genes of strain P343 appeared to be of bovine origin. Therefore, strain P343 was suggested to be a bovine RVA strain that was transmitted to pigs.
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http://dx.doi.org/10.1016/j.vetmic.2014.09.033DOI Listing
December 2014

South African life orientation teachers: (not) teaching about sexuality diversity.

J Homosex 2014 ;61(12):1687-711

a Faculdade de Ciencias da Educación , Universidade da Coruña , A Coruña , Spain.

Although South Africa is one of the most progressive countries in the world in terms of constitutional and legislative rights for LGBT individuals, education is one of many social arenas where these ideals are not carried out. Interviews with 25 practicing teachers revealed very little description of practice, but widely divergent understandings around sexual diversity that drew on various authoritative discourses, including religious teachings, educational policy, science, and the powerful human rights framework of the South African constitution. Implications for teacher education include directly engaging with these discourses and providing training, teaching materials, and practical guidelines based on existing policy.
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http://dx.doi.org/10.1080/00918369.2014.951256DOI Listing
June 2015

In tobacco BY-2 cells xyloglucan oligosaccharides alter the expression of genes involved in cell wall metabolism, signalling, stress responses, cell division and transcriptional control.

Mol Biol Rep 2014 Oct 10;41(10):6803-16. Epub 2014 Jul 10.

Plant Biology Department, Faculty of Biology, University of Havana, Havana City, Cuba.

Xyloglucan oligosaccharides (XGOs) are breakdown products of XGs, the most abundant hemicelluloses of the primary cell walls of non-Poalean species. Treatment of cell cultures or whole plants with XGOs results in accelerated cell elongation and cell division, changes in primary root growth, and a stimulation of defence responses. They may therefore act as signalling molecules regulating plant growth and development. Previous work suggests an interaction with auxins and effects on cell wall loosening, however their mode of action is not fully understood. The effect of an XGO extract from tamarind (Tamarindus indica) on global gene expression was therefore investigated in tobacco BY-2 cells using microarrays. Over 500 genes were differentially regulated with similar numbers and functional classes of genes up- and down-regulated, indicating a complex interaction with the cellular machinery. Up-regulation of a putative XG endotransglycosylase/hydrolase-related (XTH) gene supports the mechanism of XGO action through cell wall loosening. Differential expression of defence-related genes supports a role for XGOs as elicitors. Changes in the expression of genes related to mitotic control and differentiation also support previous work showing that XGOs are mitotic inducers. XGOs also affected expression of several receptor-like kinase genes and transcription factors. Hence, XGOs have significant effects on expression of genes related to cell wall metabolism, signalling, stress responses, cell division and transcriptional control.
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http://dx.doi.org/10.1007/s11033-014-3566-yDOI Listing
October 2014