Publications by authors named "Madeleine Martin"

7 Publications

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The CtrA phosphorelay integrates differentiation and communication in the marine alphaproteobacterium Dinoroseobacter shibae.

BMC Genomics 2014 Feb 13;15:130. Epub 2014 Feb 13.

Helmholtz-Centre for Infection Research (HZI), Group of Microbial Communication, Braunschweig, Germany.

Background: Dinoroseobacter shibae, a member of the Roseobacter clade abundant in marine environments, maintains morphological heterogeneity throughout growth, with small cells dividing by binary fission and large cells dividing by budding from one or both cell poles. This morphological heterogeneity is lost if the quorum sensing (QS) system is silenced, concurrent with a decreased expression of the CtrA phosphorelay, a regulatory system conserved in Alphaproteobacteria and the master regulator of the Caulobacter crescentus cell cycle. It consists of the sensor histidine kinase CckA, the phosphotransferase ChpT and the transcriptional regulator CtrA. Here we tested if the QS induced differentiation of D. shibae is mediated by the CtrA phosphorelay.

Results: Mutants for ctrA, chpT and cckA showed almost homogeneous cell morphology and divided by binary fission. For ctrA and chpT, expression in trans on a plasmid caused the fraction of cells containing more than two chromosome equivalents to increase above wild-type level, indicating that gene copy number directly controls chromosome number. Transcriptome analysis revealed that CtrA is a master regulator for flagellar biosynthesis and has a great influence on the transition to stationary phase. Interestingly, the expression of the autoinducer synthase genes luxI2 and luxI3 was strongly reduced in all three mutants, resulting in loss of biosynthesis of acylated homoserine-lactones with C14 side-chain, but could be restored by expressing these genes in trans. Several phylogenetic clusters of Alphaproteobacteria revealed a CtrA binding site in the promoters of QS genes, including Roseobacters and Rhizobia.

Conclusions: The CtrA phosphorelay induces differentiation of a marine Roseobacter strain that is strikingly different from that of C. crescentus. Instead of a tightly regulated cell cycle and a switch between two morphotypes, the morphology and cell division of Dinoroseobacter shibae are highly heterogeneous. We discovered for the first time that the CtrA phosphorelay controls the biosynthesis of signaling molecules. Thus cell-cell communication and differentiation are interlinked in this organism. This may be a common strategy, since we found a similar genetic set-up in other species in the ecologically relevant group of Alphaproteobacteria. D. shibae will be a valuable model organism to study bacterial differentiation into pleomorphic cells.
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http://dx.doi.org/10.1186/1471-2164-15-130DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4046655PMC
February 2014

Genomics and physiology of a marine flavobacterium encoding a proteorhodopsin and a xanthorhodopsin-like protein.

PLoS One 2013 4;8(3):e57487. Epub 2013 Mar 4.

Helmholtz-Centre for Infection Research, Braunschweig, Germany.

Proteorhodopsin (PR) photoheterotrophy in the marine flavobacterium Dokdonia sp. PRO95 has previously been investigated, showing no growth stimulation in the light at intermediate carbon concentrations. Here we report the genome sequence of strain PRO95 and compare it to two other PR encoding Dokdonia genomes: that of strain 4H-3-7-5 which shows the most similar genome, and that of strain MED134 which grows better in the light under oligotrophic conditions. Our genome analysis revealed that the PRO95 genome as well as the 4H-3-7-5 genome encode a protein related to xanthorhodopsins. The genomic environment and phylogenetic distribution of this gene suggest that it may have frequently been recruited by lateral gene transfer. Expression analyses by RT-PCR and direct mRNA-sequencing showed that both rhodopsins and the complete β-carotene pathway necessary for retinal production are transcribed in PRO95. Proton translocation measurements showed enhanced proton pump activity in response to light, supporting that one or both rhodopsins are functional. Genomic information and carbon source respiration data were used to develop a defined cultivation medium for PRO95, but reproducible growth always required small amounts of yeast extract. Although PRO95 contains and expresses two rhodopsin genes, light did not stimulate its growth as determined by cell numbers in a nutrient poor seawater medium that mimics its natural environment, confirming previous experiments at intermediate carbon concentrations. Starvation or stress conditions might be needed to observe the physiological effect of light induced energy acquisition.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0057487PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3587595PMC
September 2013

Genome sequences of the biotechnologically important Bacillus megaterium strains QM B1551 and DSM319.

J Bacteriol 2011 Aug 24;193(16):4199-213. Epub 2011 Jun 24.

Institute for Genomic Sciences and Department of Microbiology and Immunology, University of Maryland, School of Medicine, Baltimore, MD 21201, USA.

Bacillus megaterium is deep-rooted in the Bacillus phylogeny, making it an evolutionarily key species and of particular importance in understanding genome evolution, dynamics, and plasticity in the bacilli. B. megaterium is a commercially available, nonpathogenic host for the biotechnological production of several substances, including vitamin B(12), penicillin acylase, and amylases. Here, we report the analysis of the first complete genome sequences of two important B. megaterium strains, the plasmidless strain DSM319 and QM B1551, which harbors seven indigenous plasmids. The 5.1-Mbp chromosome carries approximately 5,300 genes, while QM B1551 plasmids represent a combined 417 kb and 523 genes, one of the largest plasmid arrays sequenced in a single bacterial strain. We have documented extensive gene transfer between the plasmids and the chromosome. Each strain carries roughly 300 strain-specific chromosomal genes that account for differences in their experimentally confirmed phenotypes. B. megaterium is able to synthesize vitamin B(12) through an oxygen-independent adenosylcobalamin pathway, which together with other key energetic and metabolic pathways has now been fully reconstructed. Other novel genes include a second ftsZ gene, which may be responsible for the large cell size of members of this species, as well as genes for gas vesicles, a second β-galactosidase gene, and most but not all of the genes needed for genetic competence. Comprehensive analyses of the global Bacillus gene pool showed that only an asymmetric region around the origin of replication was syntenic across the genus. This appears to be a characteristic feature of the Bacillus spp. genome architecture and may be key to their sporulating lifestyle.
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http://dx.doi.org/10.1128/JB.00449-11DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3147683PMC
August 2011

FaRP cell distribution in the developing CNS suggests the involvement of FaRPs in all parts of the chromatophore control pathway in Sepia officinalis (Cephalopoda).

Zoology (Jena) 2011 Apr;114(2):113-22

Laboratory Biologie des Organismes et Ecosystèmes Aquatiques, UMR MNHN/CNRS 7208/IRD 207/UPMC, Muséum National d'Histoire Naturelle, DMPA, 55 rue Buffon, CP51, F-75005 Paris, France.

The FMRFamide-related peptide (FaRP) family includes a wide range of neuropeptides that have a role in many biological functions. In cephalopods, these peptides intervene in the peculiar body patterning system used for communication and camouflage. This system is particularly well developed in the cuttlefish and is functional immediately after hatching (stage 30). In this study, we investigate when and how the neural structures involved in the control of body patterning emerge and combine during Sepia embryogenesis, by studying the expression or the production of FaRPs. We detected FaRP expression and production in the nervous system of embryos from the beginning of organogenesis (stage 16). The wider FaRP expression was observed concomitantly with brain differentiation (around stage 22). Until hatching, FaRP-positive cells were located in specific areas of the central and peripheral nervous system (CNS and PNS). Most of these areas were implicated in the control of body patterns, suggesting that FaRPs are involved in all parts of the neural body pattern control system, from the 'receptive areas' via the CNS to the chromatophore effectors.
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http://dx.doi.org/10.1016/j.zool.2010.11.002DOI Listing
April 2011

Learning packets in nursing education: reviving the past.

Nurse Educ Pract 2010 May 12;10(3):164-9. Epub 2009 Jul 12.

College of Nursing, University of Cincinnati, 3110 Vine Street, Cincinnati, OH 45221-0038, United States.

Learning packets gained popularity in nursing education in the 1960's. Recently, they have been cited as strategies for distance learning. The aim of this project was to integrate Topic Focused Learning Packets as a complementary teaching strategy for presentation of new content to large classes of undergraduate nursing students. In addition to reducing in-class content presentation time, goals included: fostering critical thinking, actively engaging the student, and providing opportunities for team-based interaction. Rationale, design process and packets will be described. The learning packet was viewed positively by the students and faculty. Among 134 students, 119 strongly agreed or agreed that the learning packet was effective in increasing their understanding of the content and achieving the course objectives.
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http://dx.doi.org/10.1016/j.nepr.2009.06.003DOI Listing
May 2010

Somatic muscle development in Sepia officinalis (cephalopoda - mollusca): a new role for NK4.

Dev Dyn 2008 Jul;237(7):1944-51

Département Milieux et Peuplements Aquatiques, Laboratoire Biologie des Organismes Marins et Ecosystèmes, CNRS UMR5178 - MNHN USM 0401, Paris, France.

Cephalopods are emerging as new developmental models. These lophotrochozoans exhibit numerous morphological peculiarities among molluscs, not only regarding their nervous system but also regarding their circulatory system, which is closed and includes three hearts. However, the molecular control of cardiac myogenesis in lophotrochozoans is largely unknown. In other groups, cardiac development depends on numerous different genes, among them NK4 seems to have a well-conserved function throughout evolution. In this study, we assessed the expression pattern of SoNK4, the Sepia officinalis NK4 homologue, during Sepia officinalis development by whole-mount in situ hybridization. SoNK4 expression begins before morphogenesis, is not restricted to prospective cardiac muscles but above all concerns mesodermal structures potentially rich in muscles such as arms and mantle. These results suggest an important role of SoNK4 in locomotory (somatic) muscles development of Sepia officinalis, and thus a new role for NK4.
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http://dx.doi.org/10.1002/dvdy.21614DOI Listing
July 2008

Enhancing breast health in rural populations: clinical nurse specialist as the key.

Clin Nurse Spec 2003 Nov;17(6):292-7

University of Cincinnati College of Nursing, Cincinnati, Ohio 45221, USA.

Four clinical nurse specialists (CNSs) were funded for a project to increase breast cancer (BC) screening practices and the knowledge of BC risk factors for women in 4 medically underserved rural counties. The goal was to implement a program to increase knowledge of breast health practices, increase access to mammography, establish linkages among CNSs and community organizations, and increase resources for breast health education and screening. Phase I: A training program (focusing on breast health, breast cancer, and screening) was presented to public health nurses from each of the 4 counties. Phase II: Project and public health nurses teamed to provide an education and screening program for rural area women. The program involved making mammograms available at no cost through a mobile mammography unit that was brought to each county. Mammograms and educational programs were provided to 141 women. The project team was clearly able to function as both clinical experts and clinical leaders. The spheres of influence for these 4 CNSs included patient/client (rural women), nursing personnel (county health department nurses), and organization/network (state health department and governmental bodies). This project, based on the Logic Model, can serve as a framework for delivering care in underserved, rural populations.
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http://dx.doi.org/10.1097/00002800-200311000-00010DOI Listing
November 2003