Establishment of a hepatocyte steatosis model using Chang liver cells

The objective of this study was to explore the experimental conditions for hepatocellular steatosis models of Chang liver cells induced by oleic acid (OA). For that, Chang liver cells were induced by different concentrations of OA for different periods. The MTT assay was used to detect hepatic cell activity, the Oil Red O staining was used to observe intracellular lipid droplets accumulation, and the glycerol phosphate oxidase method was used to detect the triglyceride (TG) content in the Chang liver cell. The hepatocellular steatosis models of Chang liver cell were established successfully by inducing with 0.2 mM OA for 24h. TG content in model cells was 379.98 ± 23.19 mg/g, which is significantly different from control cells (185.03 ± 12.68 mg/g; P < 0.01). These were considered proper conditions for establishing hepatocellular steatosis models of Chang liver cells, producing a reliable model for nonalcoholic fatty liver disease research.

Molecular characterization and phylogenetic analysis of a yak (Bos grunniens) κ-casein cDNA from lactating mammary gland

κ-Casein is one of the major proteins in the milk of mammals. It plays an important role in determining the size and specific function of milk micelles. We have previously identified and characterized a genetic variant of yak κ-casein by evaluating genomic DNA. Here, we isolate and characterize a yak κ-casein cDNA harboring the full-length open reading frame (ORF) from lactating mammary gland. Total RNA was extracted from mammary tissue of lactating female yak, and the κ-casein cDNA were synthesized by RT-PCR technique, then cloned and sequenced. The obtained cDNA of 660-bp contained an ORF sufficient to encode the entire amino acid sequence of κ-casein precursor protein consisting of 190 amino acids with a signal peptide of 21 amino acids. Yak κ-casein has a predicted molecular mass of 19,006.588 Da with a calculated isoelectric point of 7.245. Compared with the corresponding sequences in GenBank of cattle, buffalo, sheep, goat, Arabian camel, horse, and rabbit, yak κ-casein sequence had identity of 64.76-98.78% in cDNA, and identity of 44.79-98.42% and similarity of 53.65-98.42% in deduced amino acids, revealing a high homology with the other livestock species. Based on κ-casein cDNA sequences, the phylogenetic analysis indicated that yak κ-casein had a close relationship with that of cattle. This work might be useful in the genetic engineering researches for yak κ-casein.

A single nucleotide polymorphism and sequence analysis of CSN1S1 gene promoter region in Chinese Bos grunniens (yak)

The aim of this study was to investigate the polymorphism of the CSN1S1 gene promoter region in 4 Chinese yak breeds, and compare the yak CSN1S1 gene promoter region sequences with other ruminants. A Polymerase Chain Reaction-Single Strand Conformation Polymorphism protocol was developed for rapid genotyping of the yak CSN1S1 gene. One hundred fifty-eight animals from 4 Chinese yak breeds were genotyped at the CSN1S1 locus using the protocol developed. A single nucleotide polymorphism of the CSN1S1 gene promoter region has been identified in all yak breeds investigated. The polymorphism consists of a single nucleotide substitution G-->A at position 386 of the CSN1S1 gene promoter region, resulting in two alleles named, respectively, G(386) and A(386), based on the nucleotide at position 386. The allele G(386) was found to be more common in the animals investigated. The corresponding nucleotide sequences in GenBank of yak (having the same nucleotides as allele G(386) in this study), bovine, water buffalo, sheep, and goat had similarity of 99.68%, 99.35%, 97.42%, 95.14%, and 94.19%, respectively, with the yak allele A(386.).

Rapid detection of bovine milk in yak milk using a polymerase chain reaction technique

Yak milk contains a greater percentage of protein and has better quality than bovine milk. There has been an increasing focus on yak milk and milk products during the last few years. In the present study, a PCR-based assay was developed for the specific identification of bovine milk in yak milk by designing 3 primers targeting the mitochondrial ND1 gene. The use of 3 primers in a single PCR reaction set yielded 2 amplification fragments of 293 and 190 bp from bovine milk DNA, whereas only 1 amplification fragment of 293 bp was obtained in yak milk DNA. The technique was applied to raw and heat-treated binary mixtures of yak and bovine milks and enabled the specific detection of bovine milk with a detection limit of 0.1%. The assay developed is sensitive, fast, and straightforward, and it might be useful in the quality control of yak milk and milk products.

Immunosuppressive effects of rubidatum in mice

AIM

To study the effect of rubidatum (Rub) on immune function in normal mice.

METHODS

Serum lysozyme concentration (SLC) was measured using micrococcus lysodiekticus as a substrate. Delayed type hypersensitivity (DTH) was determined by measuring the thickness of the right hind footpad 24 h after the injection of 1 x 10(8) washed sRBC (50 microL 10% sRBC). Serum hemolysin concentration was determined by OD measuring at A540 after the serum was treated with 2-mercaptoethanol. Phagocytic function of peripheral leukocyte (Leu) were determined by the incorporated radioactivity of [3H]TdR. The hemolytic activity of plaque forming cell (PFC) was determined by measuring the lymphocytemediated hemolysis of sheep red blood cell in vitro. T- and B-lymphocyte transformation (TLT and BLT) were induced by phytohemagglutinin (PHA) and lipopolysacharide (LPS) respectively and measured by the incorporation of [3H]TdR.

RESULTS

Rub 125, 500, 2000 mg.kg-1.d-1 p.o. to BALB/c (or NIH) mice decreased the SLC; inhibited the phagocytosing functions of peripheral leukocytes; diminished the hemolytic activity of PFC; decreased the HC50; inhibited the DTH reaction; and showed inhibitory effects on TLT and BLT.

CONCLUSION

Rub has immunosuppressive effects on immune system in mice by affecting M phi, T, and B lymphocyte, which suggests that Rub has inhibitory effects on both nonspecific and specific immune function.