盾负泥虫对鸭跖草的专食性

盾负泥虫Lema scutellaris (Kraatz.)1年发生1代, 以成虫滞育。用与鸭跖草Commelina communis L. 同科及近缘科,属的植物对其食性进行测定,结果是食性单一,只取食鸭跖草。盾负泥虫的发生期与鸭跖草的苗期同步,幼虫的喜食与鸭跖草的多分枝特性相吻合。取食营养位与粘液细胞在鸭跖草植株上的分布及细胞的含糖量关系密切。     

抗癌药对黑胸大蠊淋巴细胞和生殖细胞核结构的损伤

噻替派浓度为0.1%、0.3%、0.5%时,黑胸大蠊精母细胞染色体断裂和裂隙率分别为6.3%、 10.5%和14.2%,显著地高于对卵母细胞的影响;和雄虫外周血淋巴细胞微核率呈平行关系,随微核率增多而增加。5-氟尿嘧啶浓度为0.1%、0.3%和0.5%时,卵母细胞染色体断裂和裂隙率分别为3.5%、9.8%和16.2%,和雌虫外周血淋巴细胞微核率呈平行关系,随微核率增多而增加,而对雄虫生殖细胞影响不显著。 Abstract:0.1%,0.3%,0.5% Thio-TEPA induced 6.3%,10.5% and 14.2% chromosome break or gap in spermatocyte of cockroach respectively.This was markedly higher than those in oocyte.In doses from 0.1 to 0.5 Tho-TEPA the frequency of micronucleus increased parallely with nuclear damage.0.1%,0.3%,0.5% 5-fluorouracil induced 3.5%,9.8%,16.2% chromosome break or gap in oocytes respectively.This was paralled with the frequency of micronucleus in lymphocytes of the female.5-fluorouracil showed not marked effect on spermatocyte.     

Flooding-induced membrane damage, lipid oxidation and activated oxygen generation in corn leaves

Flooding effects on membrane permeability, lipid peroxidation and activated oxygen metabolism in corn (Zea mays L.) leaves were investigated to determine if activated oxygens are involved in corn flooding-injury. Potted corn plants were flooded at the 4-leaf stage in a controlled environment. A 7-day flooding treatment resulted in a significant increase in chlorophyll breakdown, lipid peroxidation (malondialdehye content), membrane permeability, and the production of superoxide (O ₂ ^- ) and hydrogen peroxide (H₂O₂) in corn leaves. The effects were much greater in older leaves than in younger ones. Spraying leaves with 8-hydroxyquinoline (an O ₂ ^- scavenger) and sodium benzoate (an .OH scavenger) reduced the oxidative damage and enhanced superoxide dismutase (SOD) activity. A short duration flooding treatment elevated the activities of SOD, catalase, ascorbate peroxidase (AP), and glutathione reductase (GR), while further flooding significantly reduced the enzyme activities but enhanced the concentrations of ascorbic acid and reduced form glutathione (GSH). It was noted that the decline in SOD activity was greater than that in H₂O₂ scavengers (AP and GR). The results suggested that O ₂ ^- induced lipid peroxidation and membrane damage, and that excessive accumulation of O ₂ ^- is due to the reduced activity of SOD under flooding stress.     

The 5′ untranslated region of Arabidopsis thaliana calmodulin cDNA is an independent cDNA containing an open reading frame

A cDNA clone, pAUK1, with an open reading frame (ORF) coding for a hypothetical 164-amino-acid protein was isolated from an Arabidopsis thaliana (L.) Heynh cDNA library. The clone was attached, tail to tail, to the 3′ end of A. thaliana hexokinase cDNA. An almost identical sequence had been previously described as the 5′ untranslated region (5′ UTR) of A. thaliana calmodulin cDNA (ACaM-2). Sequence comparison with three additional A. thaliana truncated cDNA clones which appear in a database (GenBank) supports the conclusion that pAUKl is identical to the 5′ UTR of ACaM-2 and that the 5′ UTR of ACaM-2 is an independent cDNA artificially linked to A. thaliana calmodulin cDNA.     

Estimation of the primary productivity of Spartina alterniflora using a canopy model

A comprehensive canopy productivity model was built to study the productivity of a primary salt marsh grass, Spartina alterniflora. in Georgia, USA The canopy model was unique in employing plant demographic data to reconstruct canopy profiles and dynamics, which showed many growth processes that are otherwise difficult to discern in the field By linking canopy dynamics and leaf photosynthesis, the net total primary productivity of S alterniflora m a Georgia salt marsh was estimated to be 1421, 749, and 1441 g C m^-2 yr^-1 for the tall, short, and N-fertilized short populations respectively These estimates are reasonable in terms of the physiological capacity of S alterniflora and well below the range of 3000–4200 g C m^-2 yr^-1 as reported by some recent harvest studies Our detailed analysis suggested the net total productivity of S alterniflora might be greatly overestimated in the past This is mainly because of 1) failure to consider the translocation of photosynthate between aboveground and belowground parts, and 2) possible overestimates of belowground production We estimated the net belowground production to be 872, 397, and 762 g C m^-2 yr^-1 for the tall, short, and N-fertilized populations respectively After receiving nitrogen fertilizer, the net leaf carbon fixation in the short population increased from 1489 to 2487 g C m^-2 yr^-1, and our simulation showed the contribution of elevated leaf N to this increase was small, 21%, compared with that of increased leaf area, 79% Both tall and short populations allocated ca 48-49% of their annual gross leaf carbon fixation to belowground structures Nitrogen enrichment caused more allocation to aboveground parts in the short population, mainly for increasing leaf area The canopy model assumed that there was no leaf photosynthesis under tidal submergence, but if this assumption was relaxed, then leaf carbon fixation might increase 7–13% for different S alterniflora populations Although this research focused only on a salt marsh species, our general approaches, especially the coupling of leaf physiology with the reconstructed canopies, should be applicable to the study of production processes of many other plant populations     

长白山劲松林场植物群落的分类和排序

将长白山白河林业局劲松林场的５４块样地用聚类分析法划分成６个植被类群,再用ＰＣ－ＶＴＡＢ程序中经过改进的Ｂｒａｕｎ－Ｂｌａｎｑｕｅｔ学派的植被排表分析法进行综合,产生了鉴别概要表,为各个等级的植被类群筛选出诊断种。此外,还用鉴别种地样地记录进行主成分分析,以验证诊断种的有效性,结果表明,ＰＣ－ＶＴＡＢ中的植被排表分析法是筛选鉴别种的有效方法,而鉴别种以显著地提高植被分析和排序的质量。     

Dielectric properties of human red blood cells in suspension at radio frequencies

Dielectric properties of human red blood cells (RBCs) in suspension (hematocrit 50%) from 243 healthy persons (120 males, 123 females) were measured at 25 °C in a frequency range of 1–500 MHz, with a coaxial transmission line reflection method (one-side measurement). The measuring system, controlled by an IBM-PC computer, was composed of a network analyzer (HP4195A), an impedance test adapter (HP41951-61001), a coaxial line sensor, and a temperature-controlling set. The data measured revealed a statistically significant age dependence, with a critical age of about 49 years, above which permittivity and conductivity of human RBCs in suspension decreased significantly. © 1994 Wiley-Liss, Inc.     

Cell aggregation and neurite growth in gels of extracellular matrix molecules

Components of the extracellular matrix are believed to guide both nerve cells and neurites to their targets during embryogenesis and, therefore, might be useful for controlling regeneration of nervous tissue in adults. To study the influence of extracellular conditions on neurite outgrowth and cell motility, PC12 cells were suspended in three-dimensional gels containing (i) collagen (0.4 to 2 mg/mL), (ii) collagen (1 mg/mL) with added fibronectin or laminin (1 to 100 mug/mL), and (iii) agarose (7 mg/mL) with added collagen (0.001 to 1 mg/mL). Neurite outgrwoth was stimulated with nerve growth factor (NGF) and both the extent of neurite outgrowth ad cell aggregation were quantitated over 10 to 12 days in culture. The extent of neurite outgrowth was greatest at the lowest collagen concentration tested (0.4 mg/mL) and decreased with increasing concentration. The addition of laminin or fibronectin altered the extent of neurite outgrowth in collagen gels, but the differences were small. Although no neurite growth was observed in pure agarose gels, considerable neurite outgrowth occurred with the addition of small amounts (>/=0.01 mg/mL) of collagen. Mean aggregate size increased more quickly in gels with lower concentrations of collagen. For cells in 1.0 mg/mL collagen, a four- to fivefold increase in aggregate volume was seen between days 2 and 10 o the culture period, whereas the increase in DNA content during this same period was less than twofold, suggesting that the cells were aggregating, not multiplying. These results suggest that the composition of the matrix supporting nerve cells has a significant effect on both neurite outgrowth and cell motility. (c) 1994 John Wiley & Sons, Inc.     

Artificial mosaic protein containing antigenic epitopes of hepatitis E virus.

A synthetic gene encoding an artificial polypeptide composed of antigenic epitopes of the hepatitis E virus (HEV) proteins was constructed from short oligodeoxyribonucleotides by using PCR. The polypeptide comprises a mosaic of three antigenically active dominant regions from the protein encoded by open reading frame 2 (ORF2), one antigenically active region from the protein encoded by ORF3 of the Burmese HEV strain, and one antigenically active region from the protein encoded by ORF3 of the Mexican HEV strain. The mosaic protein was expressed in Escherichia coli as a chimera with glutathione S-transferase or beta-galactosidase. Guinea pig sera containing antibodies to the corresponding HEV synthetic peptides were used to demonstrate by Western immunoblot analysis and enzyme immunoassay the presence and accessibility of all HEV-specific antigenic epitopes introduced into the mosaic protein. Both the glutathione S-transferase and beta-galactosidase hybrid proteins were analyzed by using a panel of human anti-HEV-positive and -negative sera. The data obtained strongly indicate a diagnostic potential for the mosaic protein.