The genetic architecture of complete blood counts in lactating Holstein dairy cows.

Complete blood counts (CBCs) measure the abundance of individual immune cells, red blood cells, and related measures such as platelets in circulating blood. These measures can indicate the health status of an animal; thus, baseline circulating levels in a healthy animal may be related to the productive life, resilience, and production efficiency of cattle. The objective of this study is to determine the heritability of CBC traits and identify genomic regions that are associated with CBC measurements in lactating Holstein dairy cattle. The heritability of CBCs was estimated using a Bayes C0 model. The study population consisted of 388 cows with genotypes at roughly 75,000 markers and 16 different CBC phenotypes taken at one to three time points (n = 33, 131, and 224 for 1, 2, and 3 time points, respectively). Heritabilities ranged from 0.00 ± 0.00 (red cell distribution width) to 0.68 ± 0.06 (lymphocytes). A total of 96 different 1-Mb windows were identified that explained more than 1% of the genetic variance for at least one CBC trait, with 10 windows explaining more than 1% of the genetic variance for two or more traits. Multiple genes in the identified regions have functions related to immune response, cell differentiation, anemia, and disease. Positional candidate genes include RAD52 motif-containing protein 1 (RDM1), which is correlated with the degree of immune infiltration of immune cells, and C-X-C motif chemokine ligand 12 (CXCL12), which is critically involved in neutrophil bone marrow storage and release regulation and enhances neutrophil migration. Since animal health directly impacts feed intake, understanding the genetics of CBCs may be useful in identifying more disease-resilient and feed-efficient dairy cattle. Identification of genes responsible for variation in CBCs will also help identify the variability in how dairy cattle defend against illness and injury.

Genome-wide association and prediction of direct genomic breeding values for composition of fatty acids in Angus beef cattle.

BACKGROUND: As consumers continue to request food products that have health advantages, it will be important for the livestock industry to supply a product that meet these demands. One such nutrient is fatty acids, which have been implicated as playing a role in cardiovascular disease. Therefore, the objective of this study was to determine the extent to which molecular markers could account for variation in fatty acid composition of skeletal muscle and identify genomic regions that harbor genetic variation. RESULTS: Subsets of markers on the Illumina 54K bovine SNPchip were able to account for up to 57% of the variance observed in fatty acid composition. In addition, these markers could be used to calculate a direct genomic breeding values (DGV) for a given fatty acids with an accuracy (measured as simple correlations between DGV and phenotype) ranging from -0.06 to 0.57. Furthermore, 57 1-Mb regions were identified that were associated with at least one fatty acid with a posterior probability of inclusion greater than 0.90. 1-Mb regions on BTA19, BTA26 and BTA29, which harbored fatty acid synthase, Sterol-CoA desaturase and thyroid hormone responsive candidate genes, respectively, explained a high percentage of genetic variance in more than one fatty acid. It was also observed that the correlation between DGV for different fatty acids at a given 1-Mb window ranged from almost 1 to -1. CONCLUSIONS: Further investigations are needed to identify the causal variants harbored within the identified 1-Mb windows. For the first time, Angus breeders have a tool whereby they could select for altered fatty acid composition. Furthermore, these reported results could improve our understanding of the biology of fatty acid metabolism and deposition.

Number of secretory vesicles in growth hormone cells of the pituitary remains unchanged after secretion.

Immunogold-labeled transmission electron microscopy (TEM) was used to determine the total number of secretory vesicles in resting and in growth hormone (GH)-stimulated porcine pituitary cells. We identified three categories of vesicles: filled, empty, and partly empty. Resting GH cells contained more than twice as many filled vesicles than did the stimulated ones. Stimulated cells, however, contained nearly twice as many empty vesicles and 2.5 times more partly empty vesicles than did resting cells. Secretory vesicles in GH cells further revealed the localization of GH only in electron-dense vesicles in both resting and stimulated cells. The total number of secretory vesicles did not change after secretion. These results are consistent with a mechanism that, after stimulation of secretion, vesicles transiently dock and fuse at the fusion pore to release vesicular contents.

Use of actin isoform-specific antibodies to probe the domain structure in three smooth muscles.

We investigated the location of actin isoforms in relation to each other and to filament attachment sites by studying the edge-to-edge distribution of both immunofluorescence and immunogold probes in smooth muscle cells from three sources. Antibodies to alpha- or alpha,gamma-actin labeled uniformly across smooth muscle cells from each source. Antibodies to beta-cytoplasmic actin were concentrated on and near dense bodies, especially in gizzard smooth muscle, but were also located throughout the filament compartment. Double immunofluorescent labeling with antibodies to alpha- or alpha/gamma- and to beta-actin shows overlap of label at dense bodies and attachment plaques. Double immunofluorescent labeling with antibodies to alpha-actinin and to beta-actin identified dense bodies and attachment plaques as sites of colocalization. Immunogold labeling with anti-desmin was most prominent near dense bodies in the gizzard and was widely dispersed in vas deferens and arterial smooth muscle cells. Our results indicate that there is extensive overlap between the locations of contractile and cytoskeletal elements and, thus, do not support the two-domain model of smooth muscle structure. Tissue-specific organizational motif differences were seen when gizzard, vas deferens, and artery were compared and suggest that one model may not apply to these three smooth muscles.