Plant expansins are capable of inducing pH-dependent cell wall extension and stress relaxation. They may be useful as targets for crop improvement to enhance fruit development and stress resistance. Tomato is a major agricultural crop and a model plant for studying fruit development. Because only some tomato expansins have been studied, a genome-wide analysis of the tomato expansin family is necessary. In this study, we identified 25 SlEXPAs, eight SlEXPBs, one SlEXLA, four SlEXLBs, and five short homologs in the tomato genome. 25 of these genes were identified as being expressed. Bioinformatic analysis showed that although tomato expansins share similarities with those from other plants, they also exhibit specific features regarding genetic structure and amino acid sequences, which indicates a unique evolutionary process. Segmental and tandem duplication events have played important roles in expanding the tomato expansin family. Additionally, the 3-exon/2-intron structure may form the basic organization of expansin genes. We identified new expansin genes preferentially expressed in fruits (SlEXPA8, SlEXPB8, and SlEXLB1), roots (SlEXPA9, SlEXLB2, and SlEXLB4), and floral organs. Among the analyzed genes those that were inducible by hormone or stress treatments, including SlEXPA3, SlEXPA7, SlEXPB1-B2, SlEXPB8, SlEXLB1-LB2, and SlEXLB4. Our findings may further clarify the biological activities of tomato expansins, especially those related to fruit development and stress resistance, and contribute to the genetic modification of tomato plants to improve crop quality and yield.

The purpose of the present study was to investigate the regulation of propionate on the proliferation and differentiation of cultured intramuscular preadipocytes from three adult Luxi Yellow steers. The fl ow cytometry, lipid droplets stained by oil red O, and cytoplasmic fat content were detected after cultured cells were treated with different concentrations of propionate (0, 1, 3, 6 mM). The results showed that the separated cells were highly homogeneous and proliferative. Propionate (1 mM) did not signifi cantly affect (P>0.05) the cell proportion of phase G0/G1, but remarkably (P<0.05) increased the proportion of phase S+G2/M. However, the cell proportion signifi cantly increased (P<0.05) in the phase G0/G1, and decreased (P<0.05) in the phase S+G2/M when the concentration of propionate reached to 6 mM. When the confl uent intramuscular preadipocytes were treated with insulin (10 µg/ml) and dexamethasone (0.25 µM), small lipid droplets began to appear, and their number rapidly increased around the nuclei on day 6. Subsequently, when the confl uent intramuscular preadipocytes were treated with propionate, signifi cant accumulation of lipid droplets was observed on day 6, and lipid accumulation extent was dependent on the dose of propionate. In addition, cytoplasmic fat contents of cultured preadipocytes treated with propionate (1, 3, 6 mM) for 6 days were 1.5, 2, and 2 times higher than those of control group (without propionate addition). In conclusion, the present study confi rmed that there were indeed functionally active preadipocytes existing in the muscle of Chinese adult Luxi steers. Propionate may play an important physiological role in regulation of adipogenesis and stimulation of proliferation and differentiation of Luxi bovine intramuscular preadipocytes.

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AIM:To explore the change of intestinal mucosa barrier function in the progress of non-alcoholic steatohepatitis (NASH) in rats. METHODS: Thirty-two Sprague-Dawley (SD) rats were randomly divided into control group and model group. Rats in the control group were given normal diet, and rats in the model group were given fat-rich diet. Eight rats in each group were killed at end of the 8th and 12th wk, respectively. The levels of endotoxin, D-xylose, TG, TC, ALT and AST, intestinal tissue SOD and MDA as well as intestinal mucus secretory IgA (sIgA) were measured. The pathology of liver was observed by HE staining. RESULTS: At end of the 8th wk, there was no marked difference in the levels of endotoxin, D-xylose and sIgA between the two groups. At end of the 12th wk, rats in the model group developed steatohepatitis and had a higher serum level of endotoxin (P = 0.01) and D-xylose (P = 0.00) and a lower serum level of sIgA (P = 0.007). CONCLUSION: Intestinal mucosa barrier malfunction may exist in NASH rats and may be an important promoter of NASH in rats.