Enhancement of leaf nitrogen,phosphorus and potassium and seed protein in Vigna radiata by pyridoxine application

Soaking the seeds of mungbean (Vigna radiata L. Wilczek cv. K-851) in pyridoxine solution significantly enhanced leaf N, P and K concentrations at different growth stages, and seed protein concentration at harvest. Leaf N, P and K were significantly correlated with root length and seed protein. Thus, pyridoxine application not only enhanced the availability of nutrients to plants but also was responsible for the maintenance of a favourable source-sink relationship, thus ensuring more nutritious seeds of mungbean.     

Nutrients and mass in litter and top soil of ten tropical tree plantations

The importance of litter to nutrient and organic matter storage and the possible influence of species selection on soil fertility in ten stands each consisting of a separate tree species were examined in this study. The plantations had been grown under similar conditions in an arboretum in the Luquillo Experimental Forest, Puerto Rico. The species involved were: Anthocephalus chinensis, Eucalyptus × patentinervis, E. saligna, Hernandia sonora, Hibiscus elatus, Khaya nyasica, Pinus caribaea var. hondurensis, P. elliottii var. densa, Swietenia macrophylla, and Terminalia ivorensis. After 26 yr, litter mass ranged from 5 mg ha^-1 in the H. sonora stand to 27.2 Mg ha^-1 in the P. caribaea stand. Nutrients in the litter (N, P, K, Ca, and Mg) also varied widely, but stands were ranked in different order when ranked by nutrients in the litter than then ranked according to accumulation of mass. Only E. saligna and A. chinensis stands were ranked similarly in accumulation of both nutrients and mass, and the stand of H. elatus was ranked higher with respect to nutrient accumulation than to accumulation of mass. The nutrient concentration in standing leaf litter generally increased in the order of recently fallen <old intact< fragmented. Nutrient concentration of standing leaf litter appears to increase with age and depth in the litter layer. The amount of nutrients stored in the litter compartment of these plantations was in the same order of magnitude as the quantity of available nutrients in the top 10-cm of mineral soil. Total litter mass was negatively correlated with the mass-weighted concentration of N, K, and Mg. The same relationship was found for Ca in the leaf litter and N in the fine wood litter compartments. In some stands (notably P. caribaea, P. elliottii, and E. saligna), leaf litter derived from species other than the species planted in that particular stand had higher nutrient concentration than leaf litter from the planted species. Soils of the 10 stands were classified in the same soil series and had similar texture (clay soils). However, significantly different chemical characteristics were found. Results obtained by analysis of covariance and by limiting comparisons to adjacent stands with similar soil texture, indicate that different species have had different influences on the concentration of available nutrients in soil.     

Growth effects of nagilactone E on cultured cells of lettuce

Nagilactone E, a norditerpene dilactone isolated from a gymnosperm, Podocarpus nagi (Podocarpaceae), was able to stimulate the growth of cultured cells of Lactuca sativa cv. Grand Rapids at 0.1 g ml^-1 but not at 0.01 or 1 g ml^-1. Cell wet weight/unit time and cell number/unit wet weight were increased when they were recorded at the end of the 14-day incubation period. Also, the population of cells treated with that concentration of nagilactone E had a higher percentage of cells with shorter cell length compared to the control (untreated).     

Protein translocationin vitro: Biochemical characterization of genetically defined translocation components

Recent years have seen the convergence of both genetic and biochemical approaches in the study of protein translocation inE. coli. The powerful combination of these approaches is exemplified in the use of anin vitro protein synthesis-protein translocaltion system to analyze the role of genetically defined components of the protein translocation machinery. We describe in this review recent results focusing on the function of thesecA, secB, andsecY gene products and the demonstration of their requirement forin vitro protein translocation. The SecA protein was recently shown to possess ATPase activity and was proposed to be a component of the translocation ATPase. We present a speculative working model whereby the translocator complex is composed of the integral membrane proteins SecY, SecD, SecE, and SecF, forming an aqueous channel in the cytoplasmic membrane, and the tightly associated peripheral membrane protein SecA functioning as the catalytic subunit of the translocator or protein-ATPase.     

Vitamin E and fatty acids in the grey seal (Halichoerus grypus)

Summary Vitamin E levels in serum, liver and blubber (subcutaneous adipose tissue) were determined for 66 male and female grey seals of varying age in the pupping colony on Sable Island in the Northwest Atlantic by high-performance liquid chromatography (HPLC). Fatty acid concentrations were determined for all blubber specimens. Adult males and pups had significantly higher levels of vitamin E and cholesterol in serum than females and juveniles. A close relationship between vitamin E and cholesterol in serum could be observed. Suckling pups had significantly higher levels of vitamin E in liver (191 mg·kg^–1) than juveniles and adults (21–41 mg·kg^–1). Levels of vitamin E in blubber showed an age-dependent increase, with the highest levels being found in adult males; overall, these levels were much lower than in man. Vitamin E levels in blubber and liver of lactating females were only half that of adult males. This might be due to an intensive transfer of vitamin E from mother to pup during lactation, a process which may also explain the much higher levels of vitamin E in serum and liver of nursing pups. The low levels of vitamin E in blubber of seals might be a result of its high percentage of unsaturated fatty acids (79%). Highest percentage was represented by 18:1, 16:1, 22:6 and 16:0. Pups had lower values of monounsaturated, and a higher percentage of saturated fatty acids compared to mothers.     

四川青城山优食蚜蝇属二新种记述（双翅目：食蚜蝇科）

本文记述四川青城山优食蚜蝇属Eupeodes 2新种:青优食蚜蝇Eupeodes (Eupeodes) qingchengshanensis和小优食蚜蝇Eupeodes(Eupeodes)parvus,均属于Eupeodes s.str.,亚属。模式标本保存于上海农学院昆虫标本室。     

猪肠毒素源性大肠杆菌K88ac粘附抗原的核苷酸序列分析

 本文对国内流行的猪肠毒素源性大肠杆菌K88ac抗原的结构基因的核苷酸序列进行了测定。该基因由849对核苷酸组成,编码了283个氨基酸的蛋白亚单位及21个氨基酸的信号肽。与国外报道的K88ac序列的不同是我们发现一个碱基的点突变,导致在抗原决定簇内一个氨基酸的改变。从核苷酸序列推导出的氨基酸序列与另两种亚型进行了比较。     

Effect of vitamin on 2-deoxy-d-glucose uptake in human fibroblast cultures

Summary 2-Deoxy-d-glucose (2-DOG) uptake was tested in human fibroblast cultures in the presence and absence of vitamin E. Addition of 10 μg/ml vitamin E to the culture medium significantly reduced this uptake for 2-DOG concentrations of 0.005, to 10 mmol/liter (P≤0.01). The decrease of 2-DOG uptake was inversely proportional to the rise in 2-DOG concentration (P≤0.01). The presence of vitamin E reduced by 71% the average cellular level of lipid peroxides (expressed as thiobarbituric acid reactive substances) and caused a small but significant decrease in the cholesterol concentration (P≤0.01). These last results might explain the decrease in 2-DOG uptake observed in the presence of vitamin E.     

Reductions in genetic variation inDrosophila andE. coli caused by selection at linked sites

Selection at linked sites has important consequences for the properties of neutral variation and for tests of the predictions of the neutral theory of molecular evolution. We review the theory of the effect of adaptive gene substitutions on neutral variability at linked sites (hitchhiking or selective sweeps) and discuss theoretical results on the effect of selection against deleterious alleles on variation at linked sites (background selection). InDrosophila melanogaster there is a clear relation between the frequency of recombination in a given region of the chromosome and the amount of natural variability in that region. Attempts to predict this relation have given rise to models of selective sweeps and background selection. We describe possible methods of discriminating between these models, and also discuss the probable strong influence of selective sweeps on variation in largely nonrecombining genomes, with particular reference toEscherichia coll. Finally we present some unresolved questions and possible directions for future research.     

Low synonymous site variation at thelacY locus inEscherichia coli suggests the action of positive selection

We have determined the nucleotide sequences of sevenlacY alleles isolated from natural isolates ofEscherichia coli. Nucleotide heterozygosity estimates for this locus were compared to those obtained from previous studies of intraspecific variation at chromosomal loci, revealing thatlacY has unusually low synonymous site variation. The average pairwise heterozygosity of synonymous sites (Ks=0.0112+/-0.0100) is the second lowest reported and the lowest for loci that have an equivalent level of nonsynonymous variation. We consider several hypotheses to explain how different forces in evolution could act to create the observed pattern of polymorphism, including selection for translational efficiency and positive selection. Our analysis most strongly supports the hypothesis that positive selection has acted on thelacY locus inE. coli.