A cell transcriptomic profile p ovides insights into adipocytes of porcine mammary gland across development

Background Studying the composition and developmental mechanisms in mammary gland is crucial for healthy growth of newborns. The mammary gland is inherently heterogeneous, and its physiological function dependents on the gene expression of multiple cell types. Most studies focused on epithelial cells, disregarding the role of neighboring adipocytes.Results Here, we constructed the largest transcriptomic dataset of porcine mammary gland cells thus far. The dataset captured 126,829 high-quality nuclei from physiological mammary glands across five developmental stages(d 90 of gestation, G90;d 0 after lactation, L0;d 20 after lactation, L20;2 d post natural involution, PI2;7 d post natural involution, PI7). Seven cell types were identified, including epithelial cells, adipocytes, endothelial cells, fibroblasts cells, immune cells, myoepithelial cells and precursor cells. Our data indicate that mammary glands at different developmental stages have distinct phenotypic and transcriptional signatures. During late gestation(G90), the differentiation and proliferation of adipocytes were inhibited. Meanwhile, partly epithelial cells were completely differentiated. Pseudo-time analysis showed that epithelial cells undergo three stages to achieve lactation, including cellular differentiation, hormone sensing, and metabolic activation. During lactation(L0 and L20), adipocytes area accounts for less than 0.5% of mammary glands. To maintain their own survival, the adipocyte exhibited a poorly differentiated state and a proliferative capacity. Epithelial cells initiate lactation upon hormonal stimulation. After fulfilling lactation mission, their undergo physiological death under high intensity lactation. Interestingly, the physiological dead cells seem to be actively cleared by immune cells via CCL21-ACKR4 pathway. This biological process may be an important mechanism for maintaining homeostasis of the mammary gland. During natural involution(PI2 and PI7), epithelial cell populations dedifferentiate into mesenchymal stem cells to maintain the lactation potential of mammary glands for the next lactation cycle.Conclusion The molecular mechanisms of dedifferentiation, proliferation and redifferentiation of adipocytes and epithelial cells were revealed from late pregnancy to natural involution. This cell transcriptomic profile constitutes an essential reference for future studies in the development and remodeling of the mammary gland at different stages.

Accurate models and nutritional strategies for specific oxidative stress factors: Does the dose matter in swine production?

Oxidative stress has been associated with a number of physiological problems in swine,including reduced production efficiency.Recently,although there has been increased research into regulatory mechanisms and antioxidant strategies in relation to oxidative stress-induced pig production,it remains so far largely unsuccessful to develop accurate models and nutritional strategies for specific oxidative stress factors.Here,we discuss the dose and dose intensity of the causes of oxidative stress involving physiological,environmental and dietary factors,recent research models and the antioxidant strategies to provide theoretical guidance for future oxidative stress research in swine.

Effects of improved amino acid balance diet on lysine mammary utilization, whole body protein turnover and muscle protein breakdown on lactating sows

Background The study objective was to test the hypothesis that low crude protein(CP)diet with crystalline amino acids(CAA)supplementation improves Lys utilization efficiency for milk production and reduces protein turnover and muscle protein breakdown.Eighteen lactating multiparous Yorkshire sows were allotted to 1 of 2 isocaloric diets(10.80 MJ/kg net energy):control(CON;19.24%CP)and reduced CP with“optimal”AA profile(OPT;14.00%CP).Sow body weight and backfat were recorded on d 1 and 21 of lactation and piglets were weighed on d 1,14,18,and 21 of lactation.Between d 14 and 18,a subset of 9 sows(CON=4,OPT=5)was infused with a mixed solution of 3-[methyl-2H3]histidine(bolus injection)and[13C]bicarbonate(priming dose)first,then a constant 2-h[13C]bicarbonate infusion followed by a 6-h primed constant[1-13C]lysine infusion.Serial blood and milk sampling were performed to determine plasma and milk Lys enrichment,Lys oxidation rate,whole body protein turnover,and muscle protein breakdown.Results Over the 21-d lactation period,compared to CON,sows fed OPT had greater litter growth rate(P<0.05).Compared to CON,sows fed OPT had greater efficiency of Lys(P<0.05),Lys mammary flux(P<0.01)and whole-body protein turnover efficiency(P<0.05).Compared to CON,sows fed OPT tended to have lower whole body protein breakdown rate(P=0.069).Muscle protein breakdown rate did not differ between OPT and CON(P=0.197).Conclusion Feeding an improved AA balance diet increased efficiency of Lys and reduced whole-body protein turnover and protein breakdown.These results imply that the lower maternal N retention observed in lactating sows fed improved AA balance diets in previous studies may be a result of greater partitioning of AA towards milk rather than greater body protein breakdown.

Evaluating the performance of genomic selection on purebred population by incorporating crossbred data in pigs

Genomic selection(GS)has been widely used in livestock,which greatly accelerated the genetic progress of complex traits.The population size was one of the significant factors affecting the prediction accuracy,while it was limited by the purebred population.Compared to directly combining two uncorrelated purebred populations to extend the reference population size,it might be more meaningful to incorporate the correlated crossbreds into reference population for genomic prediction.In this study,we simulated purebred offspring(PAS and PBS)and crossbred offspring(CAB)base on real genotype data of two base purebred populations(PA and PB),to evaluate the performance of genomic selection on purebred while incorporating crossbred information.The results showed that selecting key crossbred individuals via maximizing the expected genetic relationship(REL)was better than the other methods(individuals closet or farthest to the purebred population,CP/FP)in term of the prediction accuracy.Furthermore,the prediction accuracy of reference populations combining PA and CAB was significantly better only based on PA,which was similar to combine PA and PAS.Moreover,the rank correlation between the multiple of the increased relationship(MIR)and reliability improvement was 0.60-0.70.But for individuals with low correlation(Cor(Pi,PA or B),the reliability improvement was significantly lower than other individuals.Our findings suggested that incorporating crossbred into purebred population could improve the performance of genetic prediction compared with using the purebred population only.The genetic relationship between purebred and crossbred population is a key factor determining the increased reliability while incorporating crossbred population in the genomic prediction on pure bred individuals.

MiR-106a targets ATG7 to inhibit autophagy and angiogenesis after myocardial infarction

Background:Myocardial infarction(MI)is an acute condition in which the heart mus-cle dies due to the lack of blood supply.Previous research has suggested that au-tophagy and angiogenesis play vital roles in the prevention of heart failure after MI,and miR-106a is considered to be an important regulatory factor in MI.But the specific mechanism remains unknown.In this study,using cultured venous endothelial cells and a rat model of MI,we aimed to identify the potential target genes of miR-106a and discover the mechanisms of inhibiting autophagy and angiogenesis.Methods:We first explored the biological functions of miR-106a on autophagy and angiogenesis on endothelial cells.Then we identified ATG7,which was the down-stream target gene of miR-106a.The expression of miR-106a and ATG7 was investi-gated in the rat model of MI.Results:We found that miR-106a inhibits the proliferation,cell cycle,autophagy and angiogenesis,but promoted the apoptosis of vein endothelial cells.Moreover,ATG7 was identified as the target of miR-106a,and ATG7 rescued the inhibition of autophagy and angiogenesis by miR-106a.The expression of miR-106a in the rat model of MI was decreased but the expression of ATG7 was increased in the infarction areas.Conclusion:Our results indicate that miR-106a may inhibit autophagy and angiogenesis by targeting ATG7.This mechanism may be a potential therapeutic treatment for MI.

Integrating genome-wide association study with multi-tissue transcriptome analysis provides insights into the genetic architecture of teat traits in pigs

Porcine teat numbers are crucial indicators of the reproductive performance of sows in the pig industry.During lactation periods,sows with fewer teats may lead to inadequate colostrum intake in piglets,which affects piglet weight gain and mortality(Tummaruk,2013).In pig breeding,high-intensity artificial selection on litter traits potentially gives rise to the functional weakening of teat traits due to the pleiotropic effects of genes affecting both traits(Chen et al.,2022).

Plant essential oils combined with organic acids restored lipopolysaccharide-induced leaky intestine via gut microbial modulation in weaned piglets

Intestine derived lipopolysaccharide(LPS)is closely related to systemic inflammation and disorders,yet little is known about its roles in the weanling stress of piglets and its potential as a nutritional intervention target.This study aimed to investigate the potential of essential oils(EO)and organic acids(OA)in mitigating weaning stress in piglets by modulating the circulation of intestine derived LPS.Seventy-two weaned piglets at 21 d old with body weight of 8.12±0.168 kg were randomly divided into a control group(CON)and an experimental group,each consisting of six pens with six piglets per pen,and were fed either a basal diet or a basal diet supplemented with 3 kg/t OA+500 g/t EO(EO+OA).On the 14th day of the feeding trial,12 weaned piglets were randomly selected from the CON group,and 6 piglets were selected from the experimental group.Based on diet composition and stress treatment,these 18 piglets were divided into the following three groups:1)CON group.Piglets were fed a basal diet and received an intraperitoneal injection of saline as a control.2)LPS group.Piglets were fed a basal diet and received an intraperitoneal injection of LPS(100μg/kg body weight)to induce stress.3)EO+OA+LPS group.Piglets were fed a basal diet supplemented with EO and OA and received an intraperitoneal injection of LPS(100μg/kg body weight)to induce stress.The results showed that EO+OA significantly ameliorated the oxidative imbalance and inflammation disorder induced by LPS in piglets'serum and intestine by inhibiting the activation of the Toll-like receptor 4(TLR4)/nuclear factor-kappa B(NF-κB)/mitogen-activated protein kinase(MAPK)signaling pathway.Furthermore,compared to the LPS group,supplementation with EO+OA restored LPS-induced reductions in Bcl-2 protein expression in the piglets'intestines(P<0.05)and mitigated morphological damage;it also enhanced both the protein expression and relative gene expression of the tight junction proteins occludin and claudin-1(P<0.05),and reduced the plasma diamine oxidase activity(DAO)and LPS content(P<0.05).Compared to the CON group,supplementation with EO+OA altered the composition of the intestinal microbiota,increasing beneficial bacteria relative abundance(Faecalibacterium)(P<0.05)and decreasing harmful bacteria relative abundance[Rikenellaceae_RC9_gut_group(P<0.01),Negativibacillus(P<0.05)].Further analysis revealed that plasma LPS content in piglets was negatively correlated with the relative abundance of Faecalibacterium(r=−0.662,P=0.021),Akkermansia(r=−0.492,P=0.031),and average daily gain(ADG)(r=−0.912,P=0.041).Plasma LPS content was also positively correlated with the plasma inflammatory factors interleukin(IL)-1β(r=0.591,P=0.021),IL-6(r=0.623,P=0.021),IL-12(r=561,P=0.031)contents,and the relative abundance of Negativibacillus(r=0.712,P=0.041).In summary,the addition of EO+OA prevents the leakage of intestine derived LPS into the circulation by improving intestinal integrity and microbiota composition,thereby enhancing antioxidant and anti-inflammatory abilities and growth performance of weaned piglets.

Excitatory amino acid transporter supports inflammatory macrophageresponses

Excitatory amino acid transporters(EAATs) are responsible for excitatory amino acid transportation and are associated with auto-immune diseases in the central nervous system and peripheral tissues.However, the subcellular location and function of EAAT2 in macrophages are still obscure. In this study,we demonstrated that LPS stimulation increases expression of EAAT2(coded by Slc1a2) via NF-κB signaling. EAAT2 is necessary for inflammatory macrophage polarization through sustaining mTORC1 activation. Mechanistically, lysosomal EAAT2 mediates lysosomal glutamate and aspartate efflux to maintain V-ATPase activation, which sustains macropinocytosis and mTORC1. We also found that mice with myeloid depletion of Slc1a2 show alleviated inflammatory responses in LPS-induced systemic inflammation and high-fat diet induced obesity. Notably, patients with type Ⅱ diabetes(T2D) have a higher level of expression of lysosomal EAAT2 and activation of mTORC1 in blood macrophages. Taken together, our study links the subcellular location of amino acid transporters with the fate decision of immune cells,which provides potential therapeutic targets for the treatment of inflammatory diseases.

Dynamic intrauterine crosstalk promotes porcine embryo implantation during early pregnancy

Dynamic crosstalk between the embryo and mother is crucial during implantation.Here,we comprehensively profile the single-cell transcriptome of pig peri-implantation embryos and corresponding maternal endometrium,identifying 4 different lineages in embryos and 13 cell types in the endometrium.Cell-specific gene expression characterizes 4 distinct trophectoderm subpopulations,showing development from undifferentiated trophectoderm to polar and mural trophectoderm.Dynamic expression of genes in different types of endometrial cells illustrates their molecular response to embryos during implantation.Then,we developed a novel tool,ExtraCellTalk,generating an overall dynamic map of maternal-foetal crosstalk using uterine luminal proteins as bridges.Through cross-species comparisons,we identified a conserved RBP4/STRA6 pathway in which embryonic-derived RBP4 could target the STRA6 receptor on stromal cells to regulate the interaction with other endometrial cells.These results provide insight into the maternal-foetal crosstalk during embryo implantation and represent a valuable resource for further studies to improve embryo implantation.