Effect of enzymatic fish frame protein hydrolysate on freeze-induced denaturation of myofibrillar protein from bighead carp fish （Aristichthys nobilis ） during frozen storage

Three kinds offish frame protein hydrolysates （PPH, APH and FPH） were prepared from fish frame of red drum （ Sciaenops ocellatus ） by papain, alkaline proteinase and flavorzyme treatment. The hydrolysates were mainly composed of peptide （83.5 % -84.6% ） and displayed different molecular weight distribution pattern. The protective effects of hydrolysates on the freeze-induced denaturation of myofibrillar protein （Mf） from bighead carp （Aristichthys nobilis） mince during storage at -20℃ for 12 weeks were investigated. The hydrolysate （5 % dried weight/wet weight） reduced the freeze-induced denaturation of Mf as evidenced by the lowered decrease in Ca-ATPase activity and reactive sulfllydryl contents as well as the impeded increase in surface hydrophobicity. Microscopic photographs indicated that the hydrolysates inhibited the growth of ice crystal in fish mince, and then prevented the aggregation of Mf during frozen storage. The protective effects of hydrolysates on freeze-induced denaturation of Mf were influenced by the molecular weight distribution. PPH had strongest cryoprotective ability among three hydrolysates.

Effect of Plant AntifreezeProteins on Porcine Embryo to Cryopreservaton

This study was to research the cryopreservation effect of plant antifieeze proteins(AFPs) on day 7 porcine expanded and hatched blastocysts that were frozen in 1.5 M glycerol by conventional slow freezing method. The developmental rates of porcine embryos frozen with 0.5 mg/ml AFPs in freeze medium and cultured for 12 and 24 hours in vitro are 25% and 0%respectively. With the concentration of AFPs increased to 5 mg/ml, the corresponding values became 80% and 40%. The hatched rates for porcine embryos frozen with 0.5 mg/ml and 5 mg/ml of AFPs and cultured for 24 hours in vitro are 0% and 20% respectively..The developmental and hatched rate of the contnrol are all 0%(0/4). These results indicate that the survival rates of porcine expanded and hatched blastocyst can be improved by supplementing freeze medium with plant AFPs.

Target deletion of the AAA ATPase PpCDC48II in Physcomitrella patens results in freezing sensitivity after cold acclimation

CDC48 is a highly conserved protein in eukaryotes and belongs to the AAA （ATPase associated with a variety of cellular activities） superfamily. It can interact with many different cofactors and form protein complexes that play important roles in various cellular processes. According to the Physcomitrella patens database, one member of the ATPases, the cell cycle gene PpCDC4811, was cloned. PpCDC48II contains two typical ATPase modules and is highly homologous to AtCDC48A. PpCDC4811 was up-regulated in mRNA levels after incubation at 0~C for 36 and 72 h. To further elucidate protein function, we disrupted the PpCDC4811 gene by transforming P. patens with the corresponding linear genomic sequences. When treated to the same freezing stress, it was found that PpCDC4811 knockout plants were less resistant to freezing treatment than wild type after acclimation. This suggested that PpCDC481I was an essential gene for low-temperature-induced freezing tolerance in P. patens cells.