AMFR gene silencing inhibits the differentiation of porcine preadipocytes.

Our study clarifies the role of the autocrine motility factor receptor (AMFR) gene in porcine preadipocyte differentiation. AMFR-siRNA was transfected into porcine preadipocytes and the preadipocytes were induced to differentiation. Subsequently, qRT-PCR was conducted to examine changes in mRNA expression of a series of genes in porcine preadipocytes, including AMFR, sterol-regulatory element-binding protein-1a (SREBP1a), SREBP2, insulin-induced gene 1 (Insig1), and Insig2. Expression changes in the mRNA of genes regulating adipocyte differentiation were also analyzed using qRT-PCR, including peroxisome proliferator-activated receptor gamma (PPARγ), CCAAT/enhancer-binding protein alpha (C/EBPα), and Kruppel-like factor 2 (KLF2). Western blot analysis was conducted to examine the changes in AMFR protein expression in porcine preadipocytes. Additionally, morphological changes in differentiated porcine preadipocytes were examined by oil red O staining, and changes in optical density (OD) values were measured using an ultraviolet spectrophotometer. At 24 h after transfection with AMFR-siRNA, AMFR mRNA expression significantly reduced (P < 0.01), and AMFR protein expression markedly decreased (P < 0.05). The mRNA expression of SREBP1a, SREBP2, Insig1, and C/EBPα was significantly reduced (P < 0.01), whereas the expression of KLF2 mRNA was significantly elevated (P < 0.01). After induction of preadipocyte differentiation, the number of lipid droplets decreased in the AMFR-silenced group, and the OD value markedly reduced (P < 0.05). In addition, the expression of C/EBPα mRNA significantly decreased (P < 0.05), whereas the expression of KLF2 mRNA considerably increased (P < 0.05). Taken together, silencing of the AMFR gene inhibits the differentiation of porcine preadipocytes.

Molecular characterization, tissue distribution, and immune reaction expression of karyopherins in the domestic silkworm (Bombyx mori).

Karyopherins, including alpha and beta types, are transport proteins in the eukaryotic cell that carry cargoes across nuclear pore complexes into or out of the nucleus. In this study, full open reading frames of one beta and three alpha types of karyopherin were cloned from cDNA of the domestic silkworm (Bombyx mori). The one beta and three alpha types' open reading frames were 2661, 1563, 1515, and 1551 base pairs long, respectively, and coded 886, 520, 504, and 516 amino acids, respectively. The alphas all had one importin-beta-binding (IBB) domain, and eight, four, or seven armadillo/beta-catenin-like repeats. The beta had 19 HEAT repeat domains, which constructed one importin-beta-N-terminal domain and one IBB domain. The recombinant proteins were expressed in Escherichia coli cells. The molecular weight of the beta type was approximately 100 kDa, and the alphas weighed approximately 60 kDa. Phylogenic tree construction revealed that the alphas could be classified into three known karyopherin-alpha subfamilies. We detected mRNA of the four karyopherins in normal 3rd day of 5th instar larvae, and in larvae injected with Gram-positive bacteria, Gram-negative bacteria, viruses, and fungi using real-time fluorescence quantitative reverse transcriptase-polymerase chain reaction, and found that the four karyopherins were widely distributed, but their expression levels were related to tissues type, the microbe injected, and the time point.

Identification of target genes for adenohypophysis-prefer miR-7 and miR-375 in cattle.

In this study, expression levels of miRNAs (miRNAs), miR-375 and miR-7, were detected in different tissues of cattle to determine whether adenohypophysis-prefer or exclusively expressed miRNAs, and target genes could be predicted by TargetScan, RNA22, and other software. Target genes related to pituitary function or reproductive traits were identified using a dual-luciferase assay. miR-375 and miR-7 were expressed differently in various tissues. miR-375 and miR-7 showed higher expression in the adenohypophysis, and there was a significant difference compared with expression in other tissues (P < 0.01). The binding sites for miR-7 were the mRNAs of bone morphogenetic protein receptor type II (BMPR2), prostaglandin F2 receptor negative regulator, gonadotropin-releasing hormone receptor, follicle-stimulating hormoneß, somatostatin receptor 1, and interleukin-1ß by bioinformatic analysis; similarly, the mRNAs of BMPR2 and leptin contained binding sites for miR-375, suggesting that these genes are affected by miR-7 or miR-375. Dual-luciferase reporter assays showed that miR-7 regulated prostaglandin F2 receptor negative regulator expression, while miR-375 regulated BMPR2 expression. The mutated plasmid and miRNA mimics were used to co-transfect NIH3T3 cells; luciferase reporter assays showed that the inhibition of luciferase activity in the wild-type cells dramatically decreased from 75 to 26% with a 3-5-nucleotide mismatch mutation into the seed region of miR-7. miR-375 had nearly lost the ability to inhibit luciferase activity, suggesting that GTCTTCC is the site of interaction between miR-7 and the prostaglandin F2 receptor negative regulator sequence and that GAACAAA is the site of interaction between miR-375 and the BMPR2 sequence.

Characterization of a novel CAPN3 transcript generated by alternative splicing in cattle.

Calpain-3 (CAPN3) is a member of the calpain family of Ca(2+)-regulated cysteine proteases, which play an important role in sarcomere remodeling and mitochondrial protein turnover, and thus, regulating beef tenderness in cattle. Currently, multiple CAPN3 transcripts have been detected in human, monkey, rat, and rabbit. However, whether this transcript is present in cattle remains unknown. In this study, we identified 2 CAPN3 transcripts in the skeletal muscle individuals of local black cattle from Jilin, China. One transcript corresponded to the known full-length protein and was referred to as CAPN3a, while the second transcript did not contain exons 2-19 and contained a single-nucleotide insert in the penultimate base of exon 1 compared to CAPN3a; this protein was referred to as CAPN3b. The expression level of CAPN3b was approximately 50-fold lower than that of CAPN3a. Moreover, CAPN3b mRNA was not translated into a functional protein because it had lost essential domains according to bioinformatic analysis. Our results not provide a foundation for understanding the function of CAPN3, but also are useful for further elucidating the effect of CAPN3 on meat quality in cattle.

Expression pattern of JMJD1C in oocytes and its impact on early embryonic development.

Cell reprogramming mediated by histone methylation and demethylation is crucial for the activation of the embryonic genome in early embryonic development. In this study, we employed quantitative real-time polymerase chain reaction (qRT-PCR) to detect mRNA levels and expression patterns of all known histone demethylases in early germinal vesicle stage and in vitro-matured metaphase II (MII) oocytes (which are commonly used as donor cells for nuclear transfer). On screening, the Jumonji domain containing 1C (JMJD1C) gene had the highest level of expression and hence was used for subsequent experiments. We also found that JMJD1C was primarily expressed in the nucleus and showed relatively high levels of expression at the 2-cell, 4-cell, 8-cell, 16-cell, morula, and blastocyst stages of embryos developed from MII oocytes fertilized in vitro. Further, we knocked down the JMJD1C gene in MII oocytes using siRNA and monitored the cleavage of zygotes and development of early embryos after in vitro fertilization. The results showed that the zygote cleavage and blastocyst rates of the transfection group were reduced by 57.1 ± 0.07 and 50 ± 0.01% respectively, which were significantly lower than those of the negative control group (P < 0.05). These data suggest that JMJD1C plays a key role in the normal development of early bovine embryos. Our results also provide a theoretical basis for the investigation of the role and molecular mechanism of histone demethylation in the early development of bovine embryos.

Association of T1740C polymorphism of L-FABP with meat quality traits in Junmu No. 1 white swine.

This study was designed to investigate a single nucleotide polymorphism in intron 1 of the liver fatty acid-binding protein (L-FABP) gene in 156 Junmu No. 1 white swine using PCR-single-strand conformational polymorphism. The association between the polymorphism and meat quality traits was also studied. The cloning and sequencing results indicated that the polymorphism in intron 1 was due to a T→C mutation at position 1740 of L-FABP, yielding three genotypes (TT, TC, and CC). Association analysis revealed that the polymorphism had a significant effect on marbling (P < 0.05): genotype CC had more marbling than TC, and TC had more marbling than TT. The polymorphism also had a highly significant effect on intramuscular fat content (P < 0.01). Genotypes CC and TC had higher intramuscular fat content than TT; there was no significant difference between CC and TC (P > 0.05). However, no significant conclusions concerning other traits could be drawn. We tentatively conclude that L-FABP is a candidate gene or a quantitative trait locus-linked gene associated with meat quality traits.

Molecular cloning and sequence analysis of follicle-stimulating hormone beta polypeptide precursor cDNA from the bovine pituitary gland.

Follicle-stimulating hormone (FSH) plays an essential role in mammalian spermatogenesis and follicular development. In a previous study, we demonstrated that some bulls carry numerous linked mutations in the FSH beta-subunit (FSHB) gene, and that these bulls have poor-quality semen, low fertility, and slightly lower serum FSH concentration compared to those without such mutations. Here, we identified the different FSHB mRNA transcripts in such individuals and analyzed the evolutionary pattern of the FSHB open reading frame (ORF) in different species. Two different lengths of FSHB mRNA transcripts corresponding to two different polyadenylation sites in the 3'-UTR were detected in wild-type bull pituitary glands, and four different mRNA transcripts resulting from the different polyadenylation sites and linked mutations were identified in mutation-bearing bull pituitaries. All transcripts had almost the same putative FSHB precursor molecule. When the ORF sequences of wild-type and mutation-bearing genes were compared with those of other tetrapod species, the leopard frog had the lowest level of homology (57.8 and 58.1%) and the buffalo had the highest level (95.9 and 96.7%), respectively. These results indicated that the bovine FSHB gene transcribes at least two classes of mRNA in the wild-type and four classes of mRNA in the mutation-bearing individuals, which provides a new insight into the bovine FSHB evolutionary pattern. In addition, these findings lay a foundation for further study of gene expression regulation and the effects of mutations on male fertility traits in cattle.

Detection of differentially expressed genes in the longissimus dorsi of Northeastern Indigenous and Large White pigs.

Recent attention in pig breeding programs has focused on the improvement of pork quality in response to increasing consumer demands. Compared to the fatty-type Northeastern Indigenous (Chinese) breed of pigs, the lean-type Large White has lower intramuscular fat and inferior eating quality from the perspective of the Chinese consumer. In order to investigate the molecular basis of differences in pork quality in Chinese indigenous and Western breeds, longissimus dorsi samples were collected from three adult Northeastern Indigenous and three adult Large White pigs. The RNAs were extracted and hybridized to the porcine Affymetrix GeneChip. Microarray analysis demonstrated differential expression of 1134 genes of which 401 have a known function. One hundred and thirty-six genes were up-regulated and 998 down-regulated in Northeastern Indigenous breed compared to Large White pigs. We screened 10 genes as candidate genes associated with pork quality. We investigated a single nucleotide polymorphism in the 5' regulatory region of the gene FABP4 in 65 Songliao black swine, using PCR-single-strand conformational polymorphism. We found this polymorphism to be highly significantly associated with marbling and intra-muscular fat content (P ≤ 0.01). Genotype BB had higher marbling than AB and AA, but there was no significant difference between AB and AA. Genotype BB and AB had higher intra-muscular fat content than AA, but there was no significant difference between BB and AB. These results help to elucidate the genetic mechanisms behind differences in pork quality and provide a theoretical basis for selection and genetic improvement of meat quality traits in pigs.