金星无核葡萄种胚培养最佳接种期的选择

金星无核葡萄的胚珠可正常受精，绝大多数受精胚在花后21d开始败育。当胚发育最为充分而又尚未败育时取胚珠进行培养，存活胚的比例较高。金星无核葡萄最适宜的接种时期为花后36～39d，此时正是浆果开始软化和着色前期。     

Transgenic Pigs with Pancreas-specific Expression of Green Fluorescent Protein

The development and regeneration of the pancreas is of considerable interest because of the role of these processes in pancreatic diseases, such as diabetes. Here, we sought to develop a large animal model in which the pancreatic cell lineage could be tracked. The pancreatic and duodenal homeobox-1 (Pdx1) gene promoter was conjugated to Venus, a green fluorescent protein, and introduced into 370 in vitro-matured porcine oocytes by intracytoplasmic sperm injection-mediated gene transfer. These oocytes were transferred into four recipient gilts, all of which became pregnant. Three gilts were sacrificed at 47–65 days of gestation, and the fourth was allowed to farrow. Seven of 16 fetuses obtained were transgenic (Tg) and exhibited pancreas-specific green fluorescence. The fourth recipient gilt produced a litter of six piglets, two of which were Tg. The founder Tg offspring matured normally and produced healthy first-generation (G1) progeny. A postweaning autopsy of four 27-day-old G1 Tg piglets confirmed the pancreas-specific Venus expression. Immunostaining of the pancreatic tissue indicated the transgene was expressed in β-cells. Pancreatic islets from Tg pigs were transplanted under the renal capsules of NOD/SCID mice and expressed fluorescence up to one month after transplantation. Tg G1 pigs developed normally and had blood glucose levels within the normal range. Insulin levels before and after sexual maturity were within normal ranges, as were other blood biochemistry parameters, indicating that pancreatic function was normal. We conclude that Pdx1-Venus Tg pigs represent a large animal model suitable for research on pancreatic development/regeneration and diabetes.     

Effect of tooth spacing on the contact selection and available selection of a dredge for the equilateral Venus clam <Emphasis Type="Italic">Gomphina melanaegis</Emphasis>

ABSTRACT:   The effect of various tooth spacing on the contact selection and the net-mouth available selection of a dredge for the equilateral Venus clam Gomphina melanaegis is evaluated by applying a contact-probability model based on the SELECT method to the data of paired-gear tests with a control dredge of 12-mm tooth spacing and four test dredges of tooth spacing 16, 20, 24 and 35 mm. A master selection curve was estimated to be s ( R ) = exp(−11.23 R  + 4.799)/(1 + exp[−11.23 R  + 4.799]) where, R is l / d , the ratio of the shell length, l , to the tooth spacing, d . The shell width of 50% retention was slightly smaller than the tooth spacing, which means that size selectivity of teeth was a type of contact selection which was dependent on the tooth spacing. Contact probability, δ, of the clams coming into contact with the teeth were 0.625, 0.467, 0.563, 0.670 and 0.976 for tooth spacing 12, 16, 20, 24 and 35 mm, respectively. This indicates that some clams entered the dredge bagnet without contacting the teeth as the sand clogging the tooth spacing carried them into the bagnet. Available selection curve of the dredge net-mouth with teeth was obtained as δ s ( R ) + 1 −  δ , and examined in terms of the legal landing size of the Venus clam.     

采收期结合1-MCP对苹果采后生理和贮藏品质的影响

为了探讨1-MCP处理对不同采收期‘维纳斯黄金’苹果的采后生理和贮藏品质的影响。研究了生长发育期为185 d（采收期Ⅰ）、192 d（采收期Ⅱ）、199 d（采收期Ⅲ）的3个采收期果实分别用浓度为0(CK)和1.0μL/L 1-MCP处理后,在常温（20±0.5）℃条件下采后生理和贮藏品质变化规律。结果表明,晚采果实的呼吸高峰和乙烯高峰较早采果实高,出现时间较早,与CK相比,1-MCP处理能显著降低3个采收期果实的乙烯释放速率和呼吸强度,明显抑制或延缓呼吸高峰和乙烯跃变高峰的出现时间。1-MCP处理对采收期Ⅰ和采收期Ⅲ果实的淀粉含量、淀粉酶活性与CK差异均不显著（P>0.05）,但1-MCP处理能保持3个采收期果实较高的硬度和原果胶含量、明显延缓可溶性果胶含量和PG酶（多聚半乳糖醛酸酶,Polygalacturonase）活性的上升,显著（P<0.05）抑制采收期Ⅱ果实贮藏13～25 d期间的淀粉酶活性上升,有效延缓淀粉转化。结果还表明,与采收期Ⅰ相比,采收期Ⅱ能维持‘维纳斯黄金’苹果较好的可溶性固形物、可滴定酸和维生素C等品质;与采收期Ⅲ相比,采收期Ⅱ能保持果实较高的硬度...     

苹果品种‘金冠’与其实生后代‘维纳斯黄金’的性状比较

比较了苹果品种‘金冠’与其自然实生后代‘维纳斯黄金’在植物学特性、果实性状、物候期及抗逆性上的差异。结果表明,与‘金冠’相比,‘维纳斯黄金’树势强,果个大,果实品质有所提高,耐贮性显著提高,果实成熟期延迟1个多月,抗逆性变化不大。