盐度对虾油中蛋白酶系、微生物和及其品质的影响

本文以虾头虾壳发酵虾油,研究了盐度对发酵过程中蛋白酶组成、微生物、各质量指标以及风味的影响。研究表明:20%以上盐度才能较好地抑制虾油腐败;发酵过程中蛋白酶组成、细菌数量是动态变化的,虾头虾壳的内源蛋白酶在发酵过程中活力逐渐减小,而微生物蛋白酶种类增加,并表现出相当高的活力;发酵前期不耐盐细菌占优势,后期耐盐细菌逐渐增加,发酵过程中真菌几乎检测不到,以上说明细菌在虾油发酵过程中发挥重要作用。盐度越高对细菌的抑制作用越强,挥发性盐基氮(TVB-N)、三甲胺(TMA)等腐败产物的生成量降低;但高盐度也抑制蛋白酶活力,不利于氨基酸态氮(AAN)生成。总体上说,24%盐度的虾油,各种呈味氨基酸比例协调,酱香浓郁,氨味和腥臭味不突出,风味最佳。

The Expression of Ca N and CaMK is Associated with Lipogenesis in the Muscle of Chicken

Intramuscular fat （IMF） content in chickens significantly contributes to meat quality. The main objective of this study was to assess the expression of calcineudn （CAN） and Ca^2＋/calmodutin-dependent protein kinase （CAME） in lipogene- sis in chicken muscle. The chickens were slaughtered and sampled at the ages of 4, 8, and 16 weeks, respectively. IMF content and the expression of CaN subunits and CaMK isoforms were measured in thigh muscle tissue. The results showed that the IMF contents were higher in chickens at the age of 16 weeks compared with those in chickens at the ages of 4 and 8 weeks （P〈0.05）. The expression levels of fatty acid synthase （FAS） and fatty acid translocase CD36 （FAT/CD36） mRNA in 16-week-old chickens were all significantly up-regulated compared with those in 4-week-old chickens （P〈0.05）. The mRNA levels of CaNB and CaMK IV in 16-week-old chickens were significantly lower than those in 4-week-old chickens （P〈0.05）. But the CaMK II mRNA levels in 16-week-old chickens were significantly higher than those in 4-week-old chickens （P〈0.05）. To investigate the roles of CaMK and CaN in adipogenesis, SV cells were incubated in standard adipogenesis medium for 24 h and treated with specific inhibitor of CaMK and CaN. The ex- pressions of CCAAT/enhancer binding protein β（C/EBPJ3）, sterol regulatory element- binding protein 1 （SREBP1） and peroxisome proliferation-activated receptor ）, （PPARy） were dramatically enhanced by CsA and CaN inhibitor （P〈0.05）. KN93, a CaMK Ⅱ inhibitor, dramatically repressed the expression of those lipogenic genes （P〈0.05）. All the results above indicated that CaN and CaMK had different effects on adipogenesis in the muscle of chickens.

A euryarchaeal histone modulates strand displacement synthesis by replicative DNA polymerases

Euryarchaeota and Crenarchaeota, the two main lineages of the domain Archaea, encode different chromatin proteins and differ in the use of replicative DNA polymerases. Crenarchaea possess a single family B DNA polymerase(Pol B), which is capable of strand displacement modulated by the chromatin proteins Cren7 and Sul7 d. Euryarchaea have two distinct replicative DNA polymerases, PolB and PolD, a family D DNA polymerase. Here we characterized the strand displacement activities of Pol B and Pol D from the hyperthermophilic euryarchaeon Pyrococcus furiosus and investigated the influence of HPf A1, a homolog of eukaryotic histones from P. furiosus, on these activities. We showed that both Pol B and Pol D were efficient in strand displacement. HPf A1 inhibited DNA strand displacement by both DNA polymerases but exhibited little effect on the displacement of a RNA strand annealed to single-stranded template DNA. This is consistent with the finding that HPf A1 bound more tightly to double-stranded DNA than to a RNA:DNA hybrid. Our results suggest that, although crenarchaea and euryarchaea differ in chromosomal packaging, they share similar mechanisms in modulating strand displacement by DNA polymerases during lagging strand DNA synthesis.

Regulatory Action of Charred Gossamer Urocteae on the Functions of Mouse Oral Fibroblasts

Objective： To explore the influence of charred Gossamer urocteae （CGU） on the functions of primary cultured mouse oral fibroblasts and reveal its mechanism in wound healing. Methods： CGU was extracted with different solvents and ethanol extract （EE）, ethyl acetate fraction （EF）, n-butanol fraction （BF） and aqueous fraction （AF） were obtained. The effects of different fractions on the proliferation, matrix metaUoproteinase-2,9 （MMP-2,9） activities, synthesis of collagen and tissue inhibitor of metalloproteinase 1 （TIMP-1） in the mouse oral fibroblasts were determined by MTT, gelatin zymography, chloramine-T method, and enzyme-linked immunosorbent assay （ELISA） respectively. Results： EE, EF and BF at high concentrations could significantly inhibit proliferation of fibroblasts （P〈0.05 or P〈0.01）, and at low concentrations EF and BF could promote proliferation of fibroblasts, and BF and AF could significantly inhibit collagen synthesis （P〈0.05 or P〈0.01）. EE, EF and AF at high concentrations could significantly increase the MMP-9 activity, and BF and AF could significantly inhibit synthesis of TIMP-1. Conclusion： CGU at high concentrations can inhibit the proliferations of fibroblasts and synthesis of collagen, and in healing of wound, CGU at high concentrations possibly has the functions of anti-fibrosis and anti-scar, and the mechanism to promote degradation of collagen is possibly related to the increase in MMP-9 activity and the inhibition of TIMP-1 synthesis.

Activating transcription factor 5 regulates lipid metabolism in adipocytes

Activating transcription factor 5(ATF5) is a member of the activating transcription factor/cA MP response element binding protein(ATF/CREB) family, and is highly expressed in liver and adipose tissue. Previous reports have shown that ATF5 promoted 3T3-L1 preadipocytes differentiation. In this study, we found that ATF5 was highly expressed in mature adipocytes, suggesting a potential role of ATF5 in mature adipocytes, which has not been reported previously. To understand the function of ATF5 in mature adipocytes, we knocked down the expression of ATF5 in 3T3-L1 mature adipocytes and observed decreased lipid droplets. Consistent with the in vitro experiment, the knockdown of ATF5 in white adipose tissue led to less adipose tissue and smaller adipocytes size. Further research revealed that the inhibition of ATF5 diminished the adipocytes size via the inhibition of fatty acid synthetase, stearyl coenzyme A desaturation enzyme 1, and the induction of carnitine palmitoyl transferase 1, one key enzyme of lipid metabolism. In addition, ATF5 knockdown in inguinal white adipose tissue improved whole body insulin sensitivity.Our work provides a new understanding of ATF5 function in mature adipocytes and a potential therapeutic target of diabetes.