Ethanol tolerance in free and sol-gel immobilised Saccharomyces cerevisiae

The tolerance of sol-gel immobilised and free Saccharomyces cerevisiae to ethanol was studied. The effects of ethanol preincubation time showed that the specific death velocity decreased from 2×10⁵ c.f.u. min^–1 for free cells to 2×10⁴ c.f.u. min^–1 for immobilised cells thus indicating that immobilised yeast was far less sensitive to the ethanol damage. The specific glucose consumption of immobilised and free cells on a per cell basis was 3×10^–12 g cell^–1 h^–1 and 9×10^–12 g cell^–1 h^–1, respectively.     

Can tolerance traits impose selection on herbivores?

Plant tolerance reduces the fitness consequences of herbivore and natural enemy damage, while resistance reduces the amount of damage suffered. In contrast to resistance, tolerance is often assumed to not affect herbivore performance and evolution. Evidence from the literature, however, suggests that it is possible for plant tolerance to affect herbivore performance and evolution, and potentially plant–herbivore coevolution. First, for cases when genetic correlations between resistance and tolerance are due to pleiotropy, the genes and loci for tolerance and resistance are the same, and as such both traits will affect herbivore performance directly. Second, it is possible that the physiological basis and mechanisms of plant tolerance – for example, changes in plant physiology and resource allocation – directly alter herbivore fitness characters. In this paper, I review the evidence for these potential effects of plant tolerance on herbivore performance, and suggest straightforward experiments to evaluate these possibilities. More generally, I propose that this untested assumption is constraining our view of plant–herbivore coevolution.     

钙对烟草叶片热激忍耐和活性氧代谢的影响

热胁迫导致烟草叶片细胞膜系统显著受损,表现为SOD活性降低和MDA含量明显升高,叶片叶绿素含量下降,活性氧增加。10mmol/LcaCl2溶液处理烟草幼苗后,能有效降低热胁迫下叶片细胞膜透性,维持较高的SOD和CAT等抗氧化酶活性,减缓O2^-形成和膜脂过氧化反应。研究结果表明,CaCl2处理提高了烟草叶片膜稳定性和膜保护酶活性,有利于保护细胞膜结构,降低高温对烟草幼苗的伤害。钙离子螯合剂EGTA能在一定程度上降低烟草叶片的抗热性。     

嗜卷书虱气调抗性形成过程中能源物质的积累与利用

报道了嗜卷书虱对高二氧化碳,低氧气调抗性形成过程中能源物质的积累以及抗性形成后在气调胁迫下能源物质的利用情况。结果表明随着抗性水平的提高。嗜卷书虱体内甘油三酯,多糖以及游离氨基酸含量均显升高。在气调胁迫环境下,嗜卷书虱抗性品系能源物质的消耗率明显低于敏感品系,甘油三酯的积累以及在气调摁迫下缓慢消耗可能是其抗气调性的主要内在机理之一。     

遮荫对13种盆栽棕榈植物生长的影响

研究13种盆栽棕榈植物在不同遮荫处理条件下的生长、叶片叶绿素含量、含水量及比叶重的变化,并通过系统聚类分析及主分量分析,将13种棕榈植物的耐阴性分为三类,其中缨络椰子、散尾葵和小琼棕较耐阴,国王椰子、假槟榔、金帝葵和美丽针葵耐阴性较差,短穗鱼尾葵、袖珍椰子、雪佛里椰子、穗花轴榈、蒲葵和棕竹等棕榈植物耐阴性居中.     

Assessment of Pollution-Induced Microbial Community Tolerance to Heavy Metals in Soil Using Ammonia-Oxidizing Bacteria and Biolog Assay

This study attempted to investigate if the tolerance of soil bacterial communities in general, and autotrophic ammonia-oxidizing bacteria (AOB) in particular, evolved as a result of prolonged exposure to metals, and could be used as an indigenous bioindicator for soil metal pollution. A soil contaminated with copper, chromium, and arsenic (CCA) was mixed with an uncontaminated garden soil (GS3) to make five test soils with different metal concentrations. A modified potential ammonium oxidation assay was used to determine the metal tolerance of the AOB community. Tolerance to Cr, Cu, and As was tested at the beginning and after up to 13 months of incubation. Compared with the reference GS3 soil, the five CCA soils showed significantly higher tolerance to Cr no matter which form of Cr (Cr³⁺, CrO₄ ^2?, or Cr₂O₇ ^2?) was tested, and the Cr tolerance correlated with the total soil Cr concentration. However, the tolerance to Cu²⁺, As³⁺, and As⁵⁺ did not differ significantly between the GS3 soil and the five CCA soils. Community level physiological profiles using Biolog microtiter plates were also used to examine the chromate tolerance of the bacterial communities extracted after six months of exposure. Our results showed that the bacterial community tolerance was altered and increased as the soil Cr concentration was increased, indicating that the culturable microbial community and the AOB community responded in a similar manner.     

Comparative mapping of loci controlling winter survival and related traits in oilseed Brassica rapa and B. napus

Winter survival is an important characteristic of oilseedBrassica that is seeded in the fall in northern climates,and it may be affected by genetic variation for other cold-regulated traits,such as freezing tolerance and vernalization responsive flowering time. Weanalyzed immortalized populations of oilseed Brassica rapa(recombinant inbred lines) and B. napus (double haploidlines) derived from crosses of annual and biennial types in order to comparethe map positions and effects of quantitative trait loci controlling wintersurvival, nonacclimated and acclimated freezing tolerances, and flowering time.The B. napus population was evaluated in multiple winters,and six of the 16 total significant QTL for winter survival were detected inmore than one winter. Correspondence in the map positions of QTL controllingdifferent traits within species provided evidence that some alleles causinggreater acclimated freezing tolerance and later flowering time also contributedto increased winter survival. Correspondence in the map positions of QTLbetween species provided evidence for allelic variation at homologous loci inB. rapa and B. napus. The potentialrole of some candidate genes in regulating these traits is discussed.     

水稻的光合作用、生长、碳同位素分辨作用及抗渗透胁迫性对CO_2浓度增高的响应(英文)

四个水稻 (OryzasativaL .)品种“IR72”、“特三矮 2号”、“桂朝 2号”和“Ⅱ优 44 80”在田间栽于含 35 μmol mol和 6 0 μmol molCO2 的塑料大棚中 ,自然光照。高浓度CO2 下供试水稻品种的光合速率变化表现为提高型 (“IR72”、“特三矮 2号”)、稳定型 (“桂朝 2号”的Pn几无变化 )和下调型 (“Ⅱ优 44 80”)。生长速率、穗重、由Δ1 3 C计算而得的长期水分利用效率和清除DPPH· 自由基的能力皆增加。除“Ⅱ优 44 80”外 ,其他 3个品种明显增高总生物量。供试品种的穗重 总生物量比不同程度地受到高浓度CO2 的改变。叶片段经PEG渗透胁迫后 ,不同的生长于高浓度CO2 者的电解质渗漏率较小。结果表明高浓度CO2 可改变水稻的光合作用和水分关系特性 ,品种间不同的响应显示了选育适于未来高浓度CO2 下具有高产和抗逆性品种的可能性。