Identification of baculovirus gene that promotes Autographa californica nuclear polyhedrosis virus replication in a nonpermissive insect cell line.

A gene that promotes Autographa californica M nuclear polyhedrosis virus (AcMNPV) replication in IPLB-Ld652Y cells, a cell line that is nonpermissive for AcMNPV, was identified in Lymantria dispar M nuclear polyhedrosis virus (LdMNPV). Cotransfection of AcMNPV DNA and a plasmid carrying the LdMNPV gene into IPLB-Ld652Y cells results in AcMNPV replication. The gene maps between 43.3 and 43.8 map units on the 162-kbp genome of LdMNPV. It comprises a 218-codon open reading frame and encodes a polypeptide with a predicted molecular mass of 25.7 kDa. The predicted polypeptide is glutamic acid and valine rich and negatively charged, with a pI of 4.61. No protein sequence motifs were identified, and no matches with known nucleotide or peptide sequences were found in the AcMNPV genome or database searches that suggest how this gene might function. A recombinant AcMNPV bearing the LdMNPV gene overcomes a block in protein synthesis observed in AcMNPV-infected IPLB-Ld652Y cells. Using Southern blotting techniques, we were unable to identify a homolog in Orgyia pseudotsugata M nuclear polyhedrosis virus, a baculovirus that is routinely propagated in IPLB-Ld652Y cells. This suggests that the LdMNPV host range is unique among the baculoviruses studied to date. We named this gene hrf-1 (for host range factor 1).     

新疆亚鳞木（比较种）角质层特征

报道了产自江苏宜兴晚泥盆世五通组新疆亚鳞木（比较种）Ｓｕｂｌｅｐｉｄｏｄｅｎｄｒｏｎ ｃｆ． ｘｉｎｊｉａｎｇｅｎｓｅＳｕｎ）的表皮角质层用荧光分析显示的特征．该种茎干表皮角质层覆于叶座及叶座间隔带,其中间隔带角质层厚于叶座．表皮细胞在间隔带与叶座表现特征不同．间隔带中部,表皮细胞呈纵长的多边形,其纵长方向与茎干延伸方向相同,细胞壁略有弯曲．间隔带靠近叶座之表皮细胞,细胞壁直,形状类似于前者;但大小仅为前者的１／２左右,且其纵长方向逐渐向叶座边缘偏转．叶座表皮细胞呈近等多边形,有胞间隙．该种茎表皮无气孔     

Outline structure of the human L1 cell adhesion molecule and the sites where mutations cause neurological disorders.

The L1 cell adhesion molecule has six domains homologous to members of the immunoglobulin superfamily and five homologous to fibronectin type III domains. We determined the outline structure of the L1 domains by showing that they have, at the key sites that determine conformation, residues similar to those in proteins of known structure. The outline structure describes the relative positions of residues, the major secondary structures and residue solvent accessibility. We use the outline structure to investigate the likely effects of 22 mutations that cause neurological diseases. The mutations are not randomly distributed but cluster in a few regions of the structure. They can be divided into those that act mainly by changing conformation or denaturing their domain and those that alter its surface properties.     

Physiological and growth responses of two African species, Acacia karroo and Themeda triandra, to combined increases in CO2 and UV-B radiation

The interactive effects of increased carbon dioxide (CO₂) concentration and ultraviolet-B (UV-B, 280–320 nm) radiation on Acacia karroo Hayne, a C₃ tree, and Themeda triandra Forsk., a C₄ grass, were investigated. We tested the hypothesis that A. karroo would show greater CO₂-induced growth stimulation than T. triandra, which would partially explain current encroachment of A. karroo into C₄ grasslands, but that increased UV-B could mitigate this advantage. Seedlings were grown in open-top chambers in a greenhouse in ambient (360 μmol mol^-1) and elevated (650 μmol mol^-1) CO₂, combined with ambient (1.56 to 8.66 kJ m^-2 day^-1) or increased (2.22 to 11.93 kJ m^-2 day^-1) biologically effective (weighted) UV-B irradiances. After 30 weeks, elevated CO₂ had no effect on biomass of A. karroo, despite increased net CO₂ assimilation rates. Interaction between UV-B and CO₂ on stomatal conductance was found, with conductances decreasing only where elevated CO₂ and UV-B were supplied separately. Increases in water use efficiencies, foliar starch concentrations, root nodule numbers and total nodule mass were measured in elevated CO₂. Elevated UV-B caused only an increase in foliar carbon concentrations. In T. triandra, net CO₂ assimilation rates were unaffected in elevated CO₂, but stomatal conductances and foliar nitrogen concentrations decreased, and water use efficiencies increased. Biomass of all vegetative fractions, particularly leaf sheaths, was increased in elevated CO₂. and was accompanied by increased leaf blade lengths and individual leaf and leaf sheath masses. However, tiller numbers were reduced in elevated CO₂. Significantly moderating effects of elevated UV-B were apparent only in individual masses of leaf blades and sheaths, and in total sheath and shoot biomass. The direct CO₂-induced growth responses of the species therefore do not support the hypothesis of CO₂-driven woody encroachment of C₄ grasslands. Rather, differential changes in resource use efficiency between grass and woody species, or morphological responses of grass species, could alter the competitive balance. Increased UV-B radiation is unlikely to substantially alter the CO₂ response of these species.     

Identification of two glutaminases inRhizobium etli

We present evidence thatRhizobium etli has two glutaminases differentiated by their thermostability and electrophoretic mobility. The thermostable glutaminase (B) is constitutive, in contrast with the thermolabile glutaminase (A), which is positively regulated by glutamine and negatively regulated by ammonium and by the carbon source. In distinction to glutaminase A, glutaminase B plays a minor role in the utilization of glutamine as a carbon source, but it may play a role in maintaining the balance of glutamine and glutamate. By complementation of theRhizobium etli LM16 mutant that lacks glutaminase A, we have cloned the gene that codes for this enzyme.     

The Human Serum Paraoxonase/Arylesterase Gene (PON1) Is One Member of a Multigene Family

A physiological role for paraoxonase (PON1) is still uncertain, but it catalyzes the hydrolysis of toxic organophosphates. Evidence that the human genome contains twoPON1-like genes, designatedPON2andPON3,is presented here. HumanPON1andPON2each have nine exons, and the exon/intron junctions occur at equivalent positions.PON1andPON2genes are both on chromosome 7 in human and on chromosome 6 in the mouse. Turkey and chicken, like most birds, lack paraoxonase activity and are very susceptible to organophosphates. However, they have aPON-like gene with 70% identity with humanPON1, PON2,andPON3.Another unexpected finding is that the deduced amino acid sequences of PON2 in human, mouse, dog, turkey, and chicken and of human PON3 are all missing the amino acid residue 105, which is lysine in human PON1. The expanded number ofPONgenes will have important implications for future experiments designed to discover the individual functions, catalytic properties, and physiological roles of the paraoxonases.     

畜禽遗传资源系统保存的理论与模拟实验研究──I．畜禽遗传资源系统保存的理论分析

本文提出了畜禽遗传资源系统保存的概念、基本思想及其群体遗传结构变化的数学模型。该理论是将一定时空内某一畜种所拥有的全部基因作为保存对象,既将活体保存作为基本方法,又将其有机地与高新生物技术结合在一起;既追求系统地保存控制畜种特性的基因资源,又可达到保存地方品种的目的。在假定无世代重叠,群体内存在选择、突变、迁移,且考虑漂变效应的情况下,本文所构建的两个数学模型可分别用来描述一个座位上多个主基因频率或数量性状群体均数的动态变化。     

兔出血症病毒主要结构多肽的氨基酸分析

兔出血症病毒主要结构多肽的氨基酸分析王恒安,杜念兴,徐为燕（南京农业大学,南京２１００９５）关键词兔出血症病毒,结构多肽,氨基酸分析有关兔出血症病毒（ＲＨＤＶ）结构多肽的报道很多,有认为只有１条,有报道４条的,也有报道多达６条的。但其主要结构多肽为分...