AQP3 Facilitates Proliferation and Adipogenic Differentiation of Porcine Intramuscular Adipocytes

Genome-wide scans identify biological and metabolic pathways regulating carcass and meat quality traits in beef cattle

Genome association studies (GWAS) provides knowledge about the genetic architecture of beef-related traits that allow linking the target phenotype to genomic information aiding breeding decision. Thus, the present study aims to uncover the genetic mechanism involved in carcass (REA: rib eye area, BF: backfat thickness, and HCW: hot carcass weight) and meat quality traits (SF: shear-force, MARB: marbling score, and IMF: intramuscular fat content) in Nellore cattle. For this, 6910 young bulls with phenotypic information and 23,859 animals genotyped with 435 k markers were used to perform the weighted single-step GBLUP (WssGBLUP) approach, considering two iterations. The top 10 genomic regions explained 8.13, 11.81, and 9.58% of the additive genetic variance, harboring a total of 119, 143, and 95 positional candidate genes for REA, BF, and HCW, respectively. For meat quality traits, the top 10 windows explained a large proportion of the total genetic variance for SF (14.95%), MARB (17.56%), and IMF (21.41%) surrounding 92, 155, and 111 candidate genes, respectively. Relevant candidate genes (CAST, PLAG1, XKR4, PLAGL2, AQP3/AQP7, MYLK2, WWOX, CARTPT, and PLA2G16) are related to physiological aspects affecting growth, carcass, meat quality, feed intake, and reproductive traits by signaling pathways controlling muscle control, key signal metabolic molecules INS / IGF-1 pathway, lipid metabolism, and adipose tissue development. The GWAS results provided insights into the genetic control of the traits studied and the genes found are potential candidates to be used in the improvement of carcass and meat quality traits.

Transcriptome analysis of skin color variation during and after overwintering of Malaysian red tilapia

The commercial value of red tilapia is hampered by variations in skin color during overwintering. In this study, three types of skin of red tilapia, including the skin remained pink color during and after overwintering (P), the skin changed from pink color to black color during overwintering and remained black color after overwintering (P-B), and the skin changed from pink color to black color during overwintering but recovered to pink color when the temperature rose after overwintering (P-B-P), were used to analyze their molecular mechanisms of color variation. The transcriptome results revealed that the P, P-B, and P-B-P libraries had 43, 42, and 43 million clean reads, respectively. The top 10 abundance mRNAs and specific mRNAs (specificity measure SPM > 0.9) were screened. After comparing intergroup gene expression levels, there were 2528, 1924, and 1939 differentially expressed genes (DEGs) between P-B-P and P-B, P-B-P and P, and P-B and P, respectively. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses of color-related mRNAs showed that a number of DEGs, including tyrp1, tyr, pmel, mitf, mc1r, asip, tat, hpdb, and foxd3, might play a potential role in pigmentation. Additionally, the co-expression patterns of genes were detected within the pigment-related pathways by the PPI network from P-B vs. P group. Furthermore, DEGs from the apoptosis and autophagy pathways, such as baxα, beclin1, and atg7, might be involved in the fading of red tilapia melanocytes. The findings will aid in understanding the molecular mechanism underlying skin color variation in red tilapia during and after overwintering as well as lay a foundation for future research aimed at improving red tilapia skin color characteristics.

miR-24-3p Dominates the Proliferation and Differentiation of Chicken Intramuscular Preadipocytes by Blocking ANXA6 Expression

Intramuscular fat (IMF) is one of the crucial factors determining meat quality. IMF deposition depends on the hyperplasia and hypertrophy of intramuscular preadipocytes, in which genes and noncoding RNAs play an important regulatory role. According to previous transcriptome analysis, ANXA6 and miR-24-3p were identified as involved in lipid metabolism in breast muscle. In this study, we further investigated their function in the proliferation and differentiation of chicken intramuscular preadipocytes. The results indicated that overexpression of ANXA6 inhibited proliferation and promoted differentiation of intramuscular preadipocytes, while knockdown of ANXA6 promoted cell proliferation and inhibited adipogenic differentiation. miR-24-3p was proved to directly bind to the 3′ untranslated region (3′UTR) of ANXA6 by dual-luciferase reporter assay. The regulatory effect of miR-24-3p on the proliferation and differentiation of intramuscular preadipocytes was opposite to that of ANXA6. Besides, the overexpression vector of ANXA6 eliminated the impact of miR-24-3p mimics on intramuscular preadipocytes. In brief, we revealed that miR-24-3p promoted proliferation but inhibited differentiation of intramuscular preadipocytes by blocking ANXA6 expression, thus dominating IMF deposition in broilers. These findings may provide a novel target for improving chicken meat quality.

Transcriptome Profiling Reveals Features of Immune Response and Metabolism of Acutely Infected, Dead and Asymptomatic Infection of African Swine Fever Virus in Pigs

African swine fever virus (ASFV) infection can result in lethal disease in pigs. ASFV encodes 150-167 proteins, of which only approximately 50 encoded viral structure proteins are functionally known. ASFV also encodes some nonstructural proteins that are involved in the regulation of viral transcription, viral replication and evasion from host defense. However, the understanding of the molecular correlates of the severity of these infections is still limited. The purpose of this study was to compare host and viral gene expression differences and perform functional analysis in acutely infected, dead and cohabiting asymptomatic pigs infected with ASFV by using RNA-Seq technique; healthy pigs were used as controls. A total of 3,760 and 2,874 upregulated genes and 4,176 and 2,899 downregulated genes were found in healthy pigs vs. acutely infected, dead pigs or asymptomatic pigs, respectively. Additionally, 941 upregulated genes and 956 downregulated genes were identified in asymptomatic vs. acutely infected, dead pigs. Different alternative splicing (AS) events were also analyzed, as were gene chromosome locations, and protein-protein interaction (PPI) network prediction analysis was performed for significantly differentially expressed genes (DEGs). In addition, 30 DEGs were validated by RT-qPCR, and the results were consistent with the RNA-Seq results. We further analyzed the interaction between ASFV and its host at the molecular level and predicted the mechanisms responsible for asymptomatic pigs based on the selected DEGs. Interestingly, we found that some viral genes in cohabiting asymptomatic pigs might integrate into host genes (DP96R, I73R and L83L) or remain in the tissues of cohabiting asymptomatic pigs. In conclusion, the data obtained in the present study provide new evidence for further elucidating ASFV-host interactions and the ASFV infection mechanism and will facilitate the implementation of integrated strategies for controlling ASF spread.

Proteomic and lipidomic analyses reveal saturated fatty acids, phosphatidylinositol, phosphatidylserine, and associated proteins contributing to intramuscular fat deposition

Intramuscular fat (IMF) content is an important factor in porcine meat quality. Previous studies have screened multiple candidate genes related to IMF deposition, but the lipids that affect IMF deposition and their lipid-protein network remain unknown. In this study, we performed proteomic and lipidomic analyses of the longissimus dorsi (LD) muscle from high-IMF (IMFH) and low-IMF (IMF-L) groups of Xidu black pigs. Eighty-eight proteins and 143 lipids were differentially abundant between the groups. The differentially abundant proteins were found to be involved in cholesterol metabolism, the PPAR signaling pathway, and ferroptosis. The triacylglycerols (TAGs) upregulated in the IMF-H group were mainly shown to be synthesized by saturated fatty acids (SFAs), while the downregulated TAGs were mainly synthesized by polyunsaturated fatty acids (PUFAs). All differentially abundant phosphatidylinositols (PIs) and phosphatidylserines (PSs) were found to be upregulated in the IMF-H group. A correlation analysis of the proteomic and lipidomic revealed candidate proteins (APOA4, VDAC3, PRNP, CTSB, GSPT1) related to TAG, PI, and PS lipids. These results revealed differences in proteins and lipids between the IMF-H and IMF-L groups, which represent new candidate proteins and lipids that should be investigated to determine the molecular mechanisms controlling IMF deposition in pigs. SIGNIFICANCE: Intramuscular fat (IMF) is a key factor affecting meat quality, and meat with a higher IMF content can have a better flavor. In this study, proteomic results show that the ferroptosis pathway, including the PRNP, VDAC3 and CP proteins, affects IMF deposition. Lipid composition is the key factor affecting IMF deposition, but there are few reports on this. In this study, through lipidomic analysis, we suggest that saturated fatty acid (SFA), phosphatidylinositol (PI), and phosphatidylserine (PS) may contribute to IMF deposition. A correlation analysis reveals the potential regulatory network between lipids and proteins. This study clarifies the difference in protein and lipid compositions in longissimus dorsi (LD) muscle with high and low IMF contents. This information suggests that it would be beneficial to increase the intramuscular fat content of pork not only from a genetic perspective but also from a nutritional perspective.