Project description:Dynamic transcriptome profiles in yak mammary gland were evaluated by sampling mammary tissue at -30, -15, 1, 15, 30, 60, 120, 180 and 240 d relative to parturition and using a bovine commercial microarray platform. Several bioinformatics tools were used to analyze the data, both as expression relative to -30 d and as expression relative to the previous time point. There were >6,000 differentially expressed transcript (DEG; FDR<0.05; P<0.05) throughout lactation with larger DEG observed at the onset (1 vs. -15d) and at the end of lactation (240 vs. 180d). Bioinformatics analysis allowed to identify lactation-related genes on yak chromosomes which laid the foundation for determination of QTL location. Among most-impacted bovine chromosomes (BTA), BTA6, BTA9 and BTA28 were induced while BTA3, BTA4 and BTA14 were inhibited throughout lactation. Functional analysis underlined an overall induction of lipid metabolism, suggesting increases in triglycerides synthesis likely regulated by PPAR signaling. Data suggested induction of amino acid metabolism while increasing secretion or protein, but decreasing proteasome, indicating a major role of amino acid handling and reduced protein degradation in the synthesis and secretion of milk proteins. Glycan biosynthesis, both for N-glycan and O-glycan, was induced suggesting increased glycan content in milk. Cell cycle and immune response, especially antigen processing and presentation, were strongly inhibited during lactation suggesting morphological changes were minimized while the mammary gland prevents immune hyper responses during lactation. Transcripts associated with response to radiation and low oxygen were enriched in the down-regulated DEG affected by stage of lactation. Except for the latter, functions affected by the transcriptomic adaptation to lactation in mammary tissue of yak were very similar to the ones observed in dairy cows.
Project description:The Jeryak is the hybrid offspring of yaks and Jersey cattle and exhibit improved milk and meat yields. Biomolecules carried within milk exosomes are important for cell growth, development, immune regulation, and various pathophysiological processes. Previous studies showed that miRNAs regulate mammary gland development, lactation, and milk quality. This study explored the relationship between milk exosomes miRNAs and lactation performance. A comparison of the milk content showed that yak milk was of a better quality compared to Jeryak milk (casein, fat, TS, SNF, lactose). Milk collected in December was superior to that collected in June for both yak and Jeryak, except for lactose concentrations. Exosomes were extracted by density gradient centrifugation and miRNA expression profiles in milk exosomes from three yaks and three Jeryaks collected in June and December were detected by small RNA sequencing. In all, 22, 120, 78, and 62 differentially expressed miRNAs (DEMs) were identified in Jun_ JY vs. Jun_ Y (P1: Jeryak in June vs. Yak in June), Jun_ JY vs. Dec_ JY (P2: Jeryak in June vs. Jeryak in December), Dec_ JY vs. Dec_ Y (P3: Jeryak in December vs. Yak in December), and Jun_ Y vs. Dec_ Y (P4: Yak in June vs. Yak in December) groups. These DEMs were enriched in functions and signaling pathways related to lactation performance. In conclusion, these findings are a reference tool to study the molecular basis of lactation performance.
Project description:miRNAs have been implicated in the regulation of milk protein synthesis and development of mammary gland. However, the function of miRNAs in regulating lactation is unclear. Therefore, the elucidation of miRNA expression profiles in MG provides a crucial entry into the understanding of the mechanisms of lactation initiation. Our present work is to examine miRNA expression profiles in bovine mammary gland, and to evaluate miRNAs function through the identification of differentially expressed miRNA between lactation and non-lactation mammary gland. Identification of novel miRNAs highlights the important function of low abundance and less conserved miRNAs. An interaction network of known miRNAs and their target genes around the lactation function was constructed to postulate the functional roles of miRNAs in mammary gland. This integrated analysis provides important information that will inspire further experimental investigations into the field of miRNAs and their targets during lactation.
Project description:Macrophages are involved in immune defense, organogenesis and tissue homeostasis. They also contribute to the different phases of mammary gland remodeling during development, pregnancy and involution post-lactation. Yet, less is known about the dynamics of mammary gland macrophages in the lactation stage. Here, we describe a macrophage population present during lactation in mice. By multi-parameter flow cytometry and single-cell RNA sequencing we reveal this population as distinct from the two resident macrophage subsets present pregestationally. These lactation-induced macrophages (LiMacs) are predominantly monocyte-derived and expand by proliferation in situ concomitant with nursing. LiMacs develop independently of IL-34 but require CSF-1 signaling and are partly microbiota-dependent. Locally, they reside adjacent to the basal cells of the alveoli and extravasate into the milk. Moreover, we also found several macrophage subsets in human milk, resembling LiMacs. Collectively, these findings reveal the emergence of unique macrophages in the mammary gland and milk during lactation.
Project description:The yak is one of the most important domestic animals in Tibetan life for providing basic resources such as milk, meat and transportation. Although yak milk production is not elevated, yak milk is superior to dairy cow milk in nutrient composition (protein and fat). However, the understanding of the metabolic mechanisms of yak mammary gland tissue during the lactation cycle remains elusive. In this study, GC-MS-based metabolomics was employed to study the metabolic variations in the yak mammary gland during the lactation cycle (pregnancy, lactation and dry period). Twenty-nine metabolites were up or downregulated during the lactation period. Compared to the dry period, during the lactation period the levels of oxalic acid were upregulated, while glycine and uridine were downregulated. Thirty-seven pathways were obtained when the 29 differential metabolites were imported into the KEGG pathway analysis. The most impacted pathways during the lactation cycle were glycine, serine and threonine metabolism; alanine, aspartate and glutamate metabolism; TCA cycle; glyoxylate and dicarboxylate metabolism; and pyrimidine metabolism. Our results provide important insights into the metabolic events involved in yak mammary gland development, lactogenesis and lactation, which can guide further research to improve milk yield and enhance the constituents of yak milk.
Project description:The objective of this study was to assess the transcriptome of the mammary tissue of four yaks during the whole lactation cycle. For this purpose, biopsies of the mammary gland were performed at -30, -15, 1, 15, 30, 60, 120, 180, and 240 days relative to parturition (d). The transcriptome analysis was performed using a commercial bovine microarray platform and the results were analyzed using several bioinformatic tools. The statistical analysis using an overall false discovery rate ≤ 0.05 for the effect of whole lactation and p < 0.05 for each comparison identified >6000 differentially expressed genes (DEGs) throughout lactation, with a large number of DEGs observed at the onset (1 d vs. -15 d) and at the end of lactation (240 d vs. 180 d). Bioinformatics analysis revealed a major role of genes associated with BTA3, BTA4, BTA6, BTA9, BTA14, and BTA28 in lactation. Functional analysis of DEG underlined an overall induction of lipid metabolism, suggesting an increase in triglycerides synthesis, likely regulated by PPAR signaling. The same analysis revealed an induction of amino acid metabolism and secretion of protein, with a concomitant decrease in proteasome, indicating a major role of amino acid handling and reduced protein degradation in the synthesis and secretion of milk proteins. Glycan biosynthesis was induced for both N-glycan and O-glycan, suggesting increased glycan content in the milk. The cell cycle and immune response, especially antigen processing and presentation, were strongly inhibited during lactation, suggesting that morphological changes are minimized during lactation, while the mammary gland prevents immune hyper-response. Transcripts associated with response to radiation and low oxygen were enriched in the down-regulated DEG affected by the stage of lactation. Except for this last finding, the functions affected by the transcriptomic adaptation to lactation in mammary tissue of yak are very similar to those observed in dairy cows.
Project description:Previously we have shown significant differences in lactation performance, mammary gland histology and expression profiles of mammary transcriptome during peak-lactation (lactation day 9; L9) between the ordinary CBA/CaH (CBA) and the superior QSi5 strains of mice. In the present study, we compared mammary gland histology between CBA and QSi5 at mid-pregnancy (pregnancy day 12; P12). We assessed lactation performance during the first 8 days of lactation of the 13th - 14th generation of the Advanced Intercross Line (AIL) (CBA X QSi5) mice. We utilized an integrative approach to analyzing mammary microarray expression profiles of CBA and QSi5 at P12 and CBA, AIL and QSi5 at L9.
Project description:Next-generation sequencing (NGS) has revolutionized systems-based analysis of miRNA expression files. The goals of this study are to obtain the miRNA expression files in dairy goat mammary gland at early lactation (10th day after parturition) and early involution (5th day after forced weaning at late lactation, 218 day after parturition).
Project description:Deep sequencing of mRNA from 6 organs of yak (Bos grunniens) Analysis of ploy(A)+ RNA of brain,heart,liver,lung,spleen, and stomach of yak (Bos grunniens)
Project description:In this study, two small RNA libraries were constructed using dry period and peak lactation dairy goat mammary gland tissues and sequenced by the Illumina Solexa high-throughput sequencing system. A total of 346 conserved and 95 novel miRNAs were identified in the dairy goat. The expression of miRNAs was confirmed by qRT-PCR in nine tissues and the mammary gland during development cycles. In addition, several candidate miRNAs that may be involved in mammary gland development and lactation were found by the comparison of miRNA expression profiles among different tissue and developmental stages of the mammary gland. This study provides the identification and profile of miRNAs related to the biology of the mammary gland in the dairy goat. The identification of these miRNAs could contribute to understanding the molecular mechanisms of lactation physiology and the development of the mammary gland in the dairy goat.