Publications by authors named "Adrian J Molenaar"

6 Publications

  • Page 1 of 1

Mammary Gland Structures Are Not Affected by an Increased Growth Rate of Yearling Ewes Post-Weaning but Are Associated with Growth Rates of Singletons.

Animals (Basel) 2021 Mar 19;11(3). Epub 2021 Mar 19.

School of Agriculture and Environment, Massey University, Palmerston North 4474, New Zealand.

The experiment aimed to examine the impacts of an increased growth rate of ewes between three and seven months of age on udder development using ultrasound and to establish whether ultrasonography could be used to identify ewe mammary structures that may be indirect indicators of singleton growth to weaning. Udder dimensions, depths of gland cistern (GC), parenchyma (PAR) and fat pad (FP) were measured in late pregnancy (P107), early lactation (L29), and at weaning (L100) in 59 single-bearing yearling ewes selected from two treatments. The 'heavy' group (n = 31) was preferentially fed prior to breeding achieving an average breeding live-weight of 47.9 ± 0.38 kg at seven months of age. The 'control' group (n = 28) had an average breeding live-weight of 44.9 ± 0.49 kg. Udder dimensions, GC, PAR and FP did not differ between treatments. Lamb growth to L100 was positively associated ( < 0.05) with PAR at P107 and GC at L29. There was no evidence of negative effects of the live-weight gain treatments on udder development of yearling ewes as measured by ultrasonography. The results suggest that this ultrasound method has the potential to identify pregnant yearling ewes which would wean heavier singletons.
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http://dx.doi.org/10.3390/ani11030884DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8003826PMC
March 2021

Epigenetic regulation of milk production in dairy cows.

J Mammary Gland Biol Neoplasia 2010 Mar 4;15(1):101-12. Epub 2010 Feb 4.

AgResearch Ltd., Ruakura Research Centre, Hamilton, 3240, New Zealand.

It is well established that milk production of the dairy cow is a function of mammary epithelial cell (MEC) number and activity and that these factors can be influenced by diverse environmental influences and management practises (nutrition, milk frequency, photoperiod, udder health, hormonal and local effectors). Thus, understanding how the mammary gland is able to respond to these environmental cues provides a huge potential to enhance milk production of the dairy cow. In recent years our understanding of molecular events within the MEC underlying bovine lactation has been advanced through mammary microarray studies and will be further advanced through the recent availability of the bovine genome sequence. In addition, the potential of epigenetic regulation (non-sequence inheritable chemical changes in chromatin, such as DNA methylation and histone modifications, which affect gene expression) to manipulate mammary function is emerging. We propose that a substantial proportion of unexplained phenotypic variation in the dairy cow is due to epigenetic regulation. Heritability of epigenetic marks also highlights the potential to modify lactation performance of offspring. Understanding the response of the MEC (cell signaling pathways and epigenetic mechanisms) to external stimuli will be an important prerequisite to devising new technologies for maximising their activity and, hence, milk production in the dairy cow.
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http://dx.doi.org/10.1007/s10911-010-9164-2DOI Listing
March 2010

The bovine lactation genome: insights into the evolution of mammalian milk.

Genome Biol 2009 24;10(4):R43. Epub 2009 Apr 24.

Department of Food Science and Technology, University of California Davis, One Shields Avenue, Davis, CA 95616, USA.

Background: The newly assembled Bos taurus genome sequence enables the linkage of bovine milk and lactation data with other mammalian genomes.

Results: Using publicly available milk proteome data and mammary expressed sequence tags, 197 milk protein genes and over 6,000 mammary genes were identified in the bovine genome. Intersection of these genes with 238 milk production quantitative trait loci curated from the literature decreased the search space for milk trait effectors by more than an order of magnitude. Genome location analysis revealed a tendency for milk protein genes to be clustered with other mammary genes. Using the genomes of a monotreme (platypus), a marsupial (opossum), and five placental mammals (bovine, human, dog, mice, rat), gene loss and duplication, phylogeny, sequence conservation, and evolution were examined. Compared with other genes in the bovine genome, milk and mammary genes are: more likely to be present in all mammals; more likely to be duplicated in therians; more highly conserved across Mammalia; and evolving more slowly along the bovine lineage. The most divergent proteins in milk were associated with nutritional and immunological components of milk, whereas highly conserved proteins were associated with secretory processes.

Conclusions: Although both copy number and sequence variation contribute to the diversity of milk protein composition across species, our results suggest that this diversity is primarily due to other mechanisms. Our findings support the essentiality of milk to the survival of mammalian neonates and the establishment of milk secretory mechanisms more than 160 million years ago.
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http://dx.doi.org/10.1186/gb-2009-10-4-r43DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2688934PMC
September 2009

The genome sequence of taurine cattle: a window to ruminant biology and evolution.

Science 2009 Apr;324(5926):522-8

To understand the biology and evolution of ruminants, the cattle genome was sequenced to about sevenfold coverage. The cattle genome contains a minimum of 22,000 genes, with a core set of 14,345 orthologs shared among seven mammalian species of which 1217 are absent or undetected in noneutherian (marsupial or monotreme) genomes. Cattle-specific evolutionary breakpoint regions in chromosomes have a higher density of segmental duplications, enrichment of repetitive elements, and species-specific variations in genes associated with lactation and immune responsiveness. Genes involved in metabolism are generally highly conserved, although five metabolic genes are deleted or extensively diverged from their human orthologs. The cattle genome sequence thus provides a resource for understanding mammalian evolution and accelerating livestock genetic improvement for milk and meat production.
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http://dx.doi.org/10.1126/science.1169588DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2943200PMC
April 2009

The acute-phase protein serum amyloid A3 is expressed in the bovine mammary gland and plays a role in host defence.

Biomarkers 2009 Feb;14(1):26-37

Dairy Science and Technology, Ruakura Research Centre, Hamilton, New Zealand.

The serum amyloid A protein is one of the major reactants in the acute-phase response. Using representational difference analysis comparing RNA from normal and involuting quarters of a dairy cow mammary gland, we found an mRNA encoding the SAA3 protein (M-SAA3). The M-SAA3 mRNA was localized to restricted populations of bovine mammary epithelial cells (MECs). It was expressed at a moderate level in late pregnancy, at a low level through lactation, was induced early in milk stasis, and expressed at high levels in most MECs during mid to late involution and inflammation/mastitis. The mature M-SAA3 peptide was expressed in Escherichia coli, antibodies made, and shown to have antibacterial activity against E. coli, Streptococcus uberis and Pseudomonas aeruginosa. These results suggest that the mammary SAA3 may have a role in protection of the mammary gland during remodelling and infection and possibly in the neonate gastrointestinal tract.
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http://dx.doi.org/10.1080/13547500902730714DOI Listing
February 2009

A deer (subfamily Cervinae) genetic linkage map and the evolution of ruminant genomes.

Genetics 2002 Apr;160(4):1587-97

AgResearch, Invermay Agricultural Centre, Mosgiel, New Zealand.

Comparative maps between ruminant species and humans are increasingly important tools for the discovery of genes underlying economically important traits. In this article we present a primary linkage map of the deer genome derived from an interspecies hybrid between red deer (Cervus elaphus) and Père David's deer (Elaphurus davidianus). The map is approximately 2500 cM long and contains >600 markers including both evolutionary conserved type I markers and highly polymorphic type II markers (microsatellites). Comparative mapping by annotation and sequence similarity (COMPASS) was demonstrated to be a useful tool for mapping bovine and ovine ESTs in deer. Using marker order as a phylogenetic character and comparative map information from human, mouse, deer, cattle, and sheep, we reconstructed the karyotype of the ancestral Pecoran mammal and identified the chromosome rearrangements that have occurred in the sheep, cattle, and deer lineages. The deer map and interspecies hybrid pedigrees described here are a valuable resource for (1) predicting the location of orthologs to human genes in ruminants, (2) mapping QTL in farmed and wild deer populations, and (3) ruminant phylogenetic studies.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1462045PMC
April 2002