钙及其拮抗剂对苹果果肉质膜透性的调节作用

采用培养果肉圆片的方法,研究了Ca2+及其拮抗剂对苹果果肉质膜透性的调节作用。结果表明,CaCl2(1、10mmol/L)降低果肉膜透性和溶质外渗速率(Js);细胞膜Ca2+通道阻塞剂Verapamil(100μmol/L)的影响不显著;细胞外Ca2+螯合剂EGTA(5mmol/L)、CaM的拮抗剂CPZ、TFP(100μmol/L)明显提高果肉膜透性和细胞溶质外渗速率。培养24h时,CaCl2能明显维持较高的SOD活性和ACC向乙烯的转化能力,EGTA、Verapamail、CPZ和TFP的作用相反。这些说明Ca2+对果肉细胞膜具有保护作用,而减少细胞外Ca2+和抑制细胞内Ca2+-CaM功能对果肉细胞膜具有伤害作用。     

优质白菜新品种‘暑绿’

 ‘暑绿’系白菜一代杂种，亲本为SW-13和SU-124(矮×苏)。该品种株型直立、束腰，叶片近圆形、翠绿色，叶柄半圆、绿白色。品质佳，株型美观，叶片与叶柄质量比值为0.67，单株质量0.40 kg。高抗炭疽病，抗TuMV、霜霉病和黑斑病。适宜在喜食青梗菜的地区作夏菜、秋菜和秋冬菜栽培。     

早熟油桃‘玫瑰红’选育

玫瑰红油桃是1992年以京玉为母本,五月火为父本进行杂交培育的早熟油桃品种。该品种在郑州6月下旬成熟,果实发育期85d左右;果面75%～100%着玫瑰红色,不裂果;平均单果重150g,最大250g;果肉乳白色,肉质硬溶,果实风味甜,可溶性固形物11%,半离核;需冷量700h,早期丰产性强,极丰产。     

农药酶免疫分析技术研究进展

自从酶免疫分析原理提出后，近30年来已获得了巨大的进步，成为农药分析的一个非常重要的方法。本文对农药酶免疫分析技术的原理和测定程序进行了评述．并总结了近年酶免疫分析在农药领域研究中的应用，最后，对农药酶免疫分析技术存在的问题和发展趋势作了讨论。     

除草剂最低致死剂量(MLHD)使用新技术概述

本文论述了荷兰MLHD技术的基本内容、技术原理、应用程序等．并针对荷兰的农业特点、开发背景，对该技术在荷兰与中国的应用前景及可行性等进行了比较分析．作者认为合理地利用该技术将有利于我国农业的可持续发展。     

除草剂靶标酮醇酸还原异构酶(KARI)研究进展

酮醇酸还原异构酶(KARI)是植物和微生物体内支链氨基酸生物合成的关键酶之一,可以作为设计除草剂的靶标,通过抑制酶的活性中断支链氨基酸的合成使植物死亡,达到除草目的。文章综述了KARI的催化性质、晶体结构以及作为除草剂靶标的研究现状。     

苦皮藤素类似物的合成与结构鉴定

以苦皮藤Celastrus angulatus Max.提取物水解产物中的多羟基β-二氢沉香呋喃为原料,合成了对粘虫Mythimna separata具有毒杀活性的苦皮藤素(Celangulin)类似物,并在活性追踪的指导下分离得到了两个具有杀虫活性的苦皮藤素类似物 A和B, 其结构经核磁共振谱、快原子轰击质谱、高分辨质谱等波谱学方法鉴定为2β,6α,8β,13-四异丁酰氧基-1β,4α,9α-三羟基-β-二氢沉香呋喃及1β,2β,6α,8β,13-五异丁酰氧基-4α,9α-二羟基-β-二氢沉香呋喃。化合物 A和B 均为新化合物,在20 mg/mL的浓度下对三龄粘虫Mythimna separata的胃毒活性(死亡率)分别为89.5%和93.2%。     

Gly-Gly肽和Gly-L-Leu肽在蛋鸡肠道内水解的研究

采用蛋鸡离体外翻肠段培养法,将小肠分为十二指肠、空肠前段、中段、后段和回肠五个部位肠段,洗净外翻。2种二肽培养液(Gly-Gly肽和Gly-L-Leu肽溶液)作为两组对照培养液,每种二肽培养液中添加肽酶抑制剂(Bestatin和Amastatin),作为试验培养液,39.5℃培养25min,每5min取样一次,测定培养液中的二肽含量。结果表明,培养5min后,含Gly-Gly肽的对照和试验培养液中均未能检测到完整Gly-Gly肽。而含Gly-L-Leu肽的对照培养液Gly-L-Leu肽的含量降低到16.75％,试验培养液则下降到43.40％。而试验培养液中Gly-L-Leu肽的含量10min后无显著降低(P>0.05)。各培养时段试验培养液Gly-L-Leu含量均显著高于对照培养液(P<0.05)。由此认为,离体肠囊在培养过程中能够迅速释放肠肽酶及一些生物活性物质,快速水解2种二肽。肽酶抑制剂(Bestatin和Amastatin)能抑制Gly-L-Leu的水解,但不能抑制Gly-Gly的水解。     

Molecular epidemiology of two fowl cholera outbreaks on a free-range chicken layer farm.

Two outbreaks of fowl cholera on a multiage free-range egg farm were investigated. The outbreaks occurred in 1994 and 2002. A total of 22 strains of Pasteurella multocida were available for study, 11 from the 1994 outbreak and 11 from the 2002 outbreak. Lesions typical of acute fowl cholera were seen in the 1994 outbreak, whereas both acute and chronic fowl cholera occurred in the 2002 outbreak. The isolates were examined in an extended phenotypic typing methodology, by a P. multocida-specific polymerase chain reaction (PCR), by the Heddleston somatic serotyping scheme, and by restriction endonuclease analysis (REA) typing using the enzyme HpaII. All 22 strains had the same phenotypic properties, all were confirmed as P. multocida by PCR, all were Heddleston serovar 4, and all had the same REA pattern. The results indicate that these 2 outbreaks were caused by the same clone of P. multocida--despite the 8-year time period between the outbreaks.     

Cloning and characterization of a bovine genomic fragment homologous to epidermal growth factor genes

Epidermal growth factor (EGF) is a potent mitogen for a variety of cell types. The 53-amino acid mature EGF protein is encoded by sequences in exons 20 and 21 of a gene spanning over 110 kb. In this study, we report the cloning and characterization of 7.5 kb of bovine genomic sequence homologous to exon 19 through 21 from EGF genes from other mammalian species. The cloned gene fragment had an unusual sequence composition in the form of an in-frame TGA codon in the coding sequence. The sequence was expressed at low levels in kidney tissue and the corresponding cDNA contained the TGA codon. The level of similarity between the bovine exonic sequence and the human, porcine, murine, feline, and canine corresponding sequences varied from 64% to 73%; however, when only sequences encoding the mature EGF protein were compared, the level of similarity between the bovine sequence and the sequence from these species was 59% to 66%. The sequence similarity of the deduced mature protein was lower (34% to 39%) than the sequence similarity of the deduced propeptide. Although the cloned sequences could originate from a bovine EGF pseudogene, the possibility exists that they originate from the functional EGF gene. An as yet unidentified mechanism to by-pass the stop codon would allow the synthesis of a functional EGF protein. Alternatively, the cloned sequence could originate from an EGF-like gene.