Gene Expression in Developing Zea mays Embryos: Regulation by Abscisic Acid of a Highly Phosphorylated 23- to 25-kD Group of Proteins

We have earlier identified a set of proteins of 23 to 25 kilodaltons (kD), covering an isoelectric point (pI) range of 6.2 to 8.2, which accumulate gradually during normal embryogenesis of Zea mays and disappear in early germination. These polypeptides can be induced prematurely in immature embryos by abscisic acid (ABA) treatment. We report here that the more acidic protein forms are due to post-translational phosphorylation of at least two polypeptides of 23 kD, pI 8.2 and 25 kD, pI 8.0. A polyclonal antiserum was obtained which recognizes all forms of both the 23-kD and 25-kD polypeptides. Recovery of cDNA clones corresponding to these proteins was accomplished by hybridization with cDNA made from size-selected mRNA enriched for these sequences. Hybrid selection experiments demonstrate that clone MA12 specifically hybridizes with mRNAs encoding the 23-kD and 25-kD protein set which are recognized by the antiserum. By Northern hybridization analysis, the RNA encoded by clone MA12 is shown to accumulate in mature embryos and to be induced in young embryos upon ABA incubation.     

Phytochrome-mediated light regulation of nitrate reductase expression in squash cotyledons

In etiolated squash (Cucurbita maxima L.) cotyledons, nitrate-inducible NADH:nitrate reductase activity and protein were increased in darkness by red light pulses with red/far-red photoreversibility. Continuous far-red light also led to increased levels of nitrate reductase activity and protein. Poly(A)+RNA, which hybridizes to squash nitrate reductase cDNA, was also increased by light treatments. Thus, we found that after nitrate triggering, nitrate reductase expression appears to be regulated by light via phytochrome.     

The fine structure of the dorsal ocelli in the male bibionid fly

The dorsal ocelli of bibionid flies, details of which have not previously been described, were examined in males of Dilophus febrilis. The three ocelli are combined within an elevated chitin capsule, in a medial position between the enlarged dorsal compound eyes. The biconvex lenses show a multiple layering of up to 150 regularly spaced, clear and dense cuticle zones (100 nm spacing) which probably provide some spectral filtering, suggested by in vivo observations with an epifluorescence microscope. The corneagenous cells and the retina with 100-200 photoreceptor cells are adjoined proximally. A distal retina zone comprises the rhabdoms, which are laterally connected in an hexagonal network. The rhabdoms are between 4 and 15 mum in length; they decrease gradually from the dorsal to the ventral retina region. A middle retina zone comprises the receptor somata, a proximal zone, their axons. Synaptic contacts between axons and interneuron dendrites, feedback synapses to axons, and axo-axonic synapses are found, showing varying pre-synaptic structures. A possible functional role of the ocelli is discussed.     

金缕梅科(广义)的叶结构及分类

金缕梅科(广义)Hamamelidaceae包括29属,约140种。 此科的化石出现得较早,是双子叶植物中的一个比较古老的科。 本文的目的是系统研究此科透明叶的各种性状特征,并检验它们是否具有分类学意义。 本文研究了金缕梅科29属、60余种的叶的各种性状在科内的分布及演化趋势,并根据这方面的证据对此科的分类提出一些修正意见,系统描述部分介绍了金缕梅科各属叶的形态特征。     

飞蝗复眼生理和结构上的节律变化

采用细胞内记录和光镜方法研究了飞蝗(Locusta migratoria)夜间和日间在暗适应和明适应状态下小网膜细胞角敏感度以及晶锥和小网膜细胞之间区域结构上的变化.结果表明小网膜细胞角敏感度的变化不仅仅由于晶锥周围主色素细胞色素颗粒的移动,而且也由于小眼感杆束结构上的节律变化.     

应用明胶颗粒凝集试验检测人免疫缺陷病病毒(HIV-1)抗体

明胶颗粒凝集试验是测定HIV-1抗体的新方法。本研究将明胶颗粒凝集试验与ELISA法、蛋白印迹法和间接免疫荧光试验做了比较,观察本方法的敏感性和特异性。共检测了195份来自法国和非洲象牙海岸的血清,凡是蛋白印迹法阳性的血清,明胶颗粒凝试验都是阳性。这表明本方法是特异和敏感的,方法简便,不需特殊仪器,省时,可用于HIV-1抗体的筛选,但多数蛋白印迹法可疑的血清,明胶颗粒试验均阴性。因此,对蛋白印迹法测出的可疑者应该用数种方法进行追踪检测。     

哈巴德布鲁克生态系统（H. B. E.）及其五号流域（W-5）研究

一、前言哈巴德布鲁克实验林(Hubbard Brook Experimental Forest)位于美国东北部新罕布什尔州中部的白山国家森林中。该地区位于典型温带湿润气候区内,年平均降水量为129.5cm,全年月平均降水量变化不大,冬雪夏雨。蒸发蒸腾量以每年6—9月为最大(Likens等,1977;Bormann等,1979)。该实验林为北美温带落叶阔叶林,属红果云杉(Picea rubens)-阔叶林。Hubbard Brook Ecosystem Study(HBES)是开始最     

苏芸金杆菌浓缩液的保存和不用二甲苯的防腐剂配方

在苏芸金杆菌浓缩商品制剂中,通常含有3—4％的二甲苯以防止芽孢的萌发。除此以外,二甲苯还能防止各种腐生微生物污染,尤其是肠杆菌和真菌。最近,一种用苏芸金杆菌血清型H3a3b制备的称为Futufa的超浓缩液已经问世,其中不含二甲苯,用于防治枞色卷蛾(属鳞     

噬菌体T7基因6.5和6.7的克隆及其缺失变种的构建

 用适当的限制性内切酶,将噬菌体T7基因6.5和6.7从整个噬菌体T7基因组中分离出来,插入到质粒pBR322中去,转化E.Coli HMS174,筛选出这两个基因的成功克隆。运用同样手段,从整个噬菌体T7基因组中分离出含有部分基因6编码序列,而不含基因6.5和6.7编码序列的T7DNA片段,插入到pBR322的衍生质粒中去,转化Ecoli C1757,再用含有基因6和基因7的双突变噬菌体T7去感染这一转化菌,通过同源交叉而得到缺失基因6.5和6.7的噬菌体T7缺失变种。这种噬菌体只能在载有噬菌体T7基因6.5和6.7,或者只载有基因6.7质粒的寄主中增殖。通过噬菌体结构蛋白电泳分析证明,这种噬菌体丢失了野生型菌体T7所具有的两条结构蛋白带。