Heterologous hybridization to a complementary DNA microarray reveals the effect of thermal acclimation in the endothermic bluefin tuna (Thunnus orientalis)

The temperature stress that pelagic fishes experience can induce physiological and behavioural changes that leave a signature in gene expression profiles. We used a functional genomics approach to identify genes that were up- or down-regulated following thermal stress in the Pacific bluefin tuna. Following the acclimation period, 113, 81 and 196 genes were found to be differentially expressed between the control (20 °C) and cold (15°) treatment groups, in ventricle, red muscle and white muscle, respectively. The genes whose expression levels were responsive to thermal acclimation varied according to muscle fibre type, perhaps reflecting the tissue-specific degrees of endothermy characteristic of this species.     

Self‐association of streptococcus pyogenes collagen‐like constructs into higher order structures

A number of bacterial collagen‐like proteins with Gly as every third residue and a high Pro content have been observed to form stable triple‐helical structures despite the absence of hydroxyproline (Hyp). Here, the high yield cold‐shock expression system is used to obtain purified recombinant collagen‐like protein (V‐CL) from Streptococcus pyogenes containing an N‐terminal globular domain V followed by the collagen triple‐helix domain CL and the modified construct with two tandem collagen domains V‐CL‐CL. Both constructs and their isolated collagenous domains form stable triple‐helices characterized by very sharp thermal transitions at 35–37°C and by high values of calorimetric enthalpy. Procedures for the formation of collagen SLS crystallites lead to parallel arrays of in register V‐CL‐CL molecules, as well as centrosymmetric arrays of dimers joined at their globular domains. At neutral pH and high concentrations, the bacterial constructs all show a tendency towards aggregation. The isolated collagen domains, CL and CL‐CL, form units of diameter 4–5 nm which bundle together and twist to make larger fibrillar structures. Thus, although this S. pyogenes collagen‐like protein is a cell surface protein with no indication of participation in higher order structure, the triple‐helix domain has the potential of forming fibrillar structures even in the absence of hydroxyproline. The formation of fibrils suggests bacterial collagen proteins may be useful for biomaterials and tissue engineering applications.     

Local adaptation of stress related traits in Drosophila buzzatii and Drosophila simulans in spite of high gene flow

We addressed the question if local adaptation to a thermal gradient is possible in spite of a high gene flow among closely spaced populations of two species of Drosophila from the island of La Gomera (Canary Islands). Variation in multiple traits related to stress resistance in different life stages was measured in both species in flies collected from five localities at different altitudes and thereby with different climatic conditions. Based on microsatellite loci, the populations were not genetically differentiated. However, 18 of the 24 independent traits measured showed significant differentiation among populations of Drosophila buzzatii, but only nine of 25 for Drosophila simulans. This difference in the number of traits might reflect higher habitat specificity and thus higher potential for local adaptation of D. buzzatii than D. simulans. We found clinal variation, as some traits showed significant linear regressions on altitude, but more on altitude cubed.     

三种油茶幼苗对低温胁迫的生理响应及其抗寒性综合评价

以普通油茶Camellia oleifera、高州油茶C. drupifera和红花油茶C. semiserrata 1年生幼苗为试材,通过模拟低温胁迫,分别对其进行6 ℃低温处理,持续0、24、48、72 h以及恢复常温25 ℃后处理24 h,测定各处理幼苗的生理指标,并用主成分分析法综合评价3种油茶幼苗的抗寒性。结果表明,3种油茶的叶绿素含量和相对含水量随胁迫时间的延长而下降,而可溶性蛋白含量则随胁迫时间延长显著上升。在低温处理72 h时,高州油茶的叶绿素含量和可溶性蛋白含量与对照相比差异极显著,分别下降了64.67%和上升了705.67%;而普通油茶叶绿素含量和可溶性蛋白含量与对照相比仅下降34.35 %和上升443.10%,表现出较强的抗寒性。3种油茶抗寒性由强到弱的顺序为普通油茶＞红花油茶＞高州油茶。     

壳聚糖提高香蕉幼苗抗冷性的效应

壳聚糖(CS)预处理可降低低温胁迫下香蕉幼苗叶细胞膜脂过氧化水平和膜透性增加的程度以及超氧化物歧化酶(SOD)、过氧化物酶(POD)活性的下降幅度,提高过氧化氢酶(CAT)的活性;0.3%的壳聚糖的保护效果最好.     

人工扩繁代异色瓢虫卵和成虫最适冷藏条件的探讨

探讨了人工扩繁异色瓢虫时卵和成虫的最适冷藏条件。卵的最适保存温度是 1 0℃ ,冷藏 1 5d内孵化率平均在 60 %以上。成虫的最适保存温度是 1 0℃ ,如将刚羽化的成虫直接在该温度下冷藏 ,冷藏 40d时存活率能保持在 5 0 %左右 ;如将刚羽化成虫先在 1 5℃、0L∶2 4D条件下处理 1 6d,然后置于 1 0℃下冷藏 ,经冷藏 70d后存活率接近 1 0 0 % ,冷藏 90d后存活率仍高于 70 %。表明经一定条件下预处理后再冷藏成虫能保持较高的存活率和较长的存活期 ,可满足人工扩繁时对成虫的冷藏要求。     

Chill injury in the eggs of the migratory locust, Locusta migratoria （Orthoptera： Acrididae）： the time-temperature relationship with high-temperature interruption

Abstract Mortality of the overwintering egg of the migratory locust, Locusta migratoria L. , was attributed to chill injury because of its occurrence well above the egg's super cooling point. In this study, two parameters, upper limit of chill injury zone (ULCIZ) and sum of the injurious temperature (SIT), were used to examine the locust egg's cold hardiness. The value of ULCIZ for the locust egg is 1.06 ± 0.54°C, and the SIT is -329.7 (hour · degree). The superoxide dismutase (SOD) and catalase (CAT) activities changed dramatically after cold stress, indicating that oxygen and hydroxide free radicals are probably efficiently detoxified at low temperatures. It was suggested that the nature of chill injury in locust egg might be a complex of metabolic disorder and a non-proportional decrease in enzymatic reaction and transports, because the LDH activity at low temperature increased significantly and the ATPase activity decreased with prolonged duration of exposure to low temperatures. The results from high temperature interruption revealed that the high temperature intervals significantly increased the survival of locust eggs.     

The Effects of Cold Acclimation of Winter Wheat Plants on Changes in CO<Subscript>2</Subscript> Exchange and Phenolic Compound Formation

We studied CO₂ exchange and phenolic compound production in various organs of unhardened and hardened winter wheat (Triticum aestivum L.) plants. The rates of CO₂ assimilation at saturating illumination (photosynthesis) and CO₂ evolution in darkness (respiration) declined substantially at the autumnal decrease of ambient temperature. However, because of a higher cold resistance of photosynthesis, the ratio of photosynthesis to respiration rates increased 1.5-fold. These gas exchange changes were accompanied by the accumulation of total soluble phenolics in leaves and a polymeric phenolic compound lignin in roots. We did not observe any changes in the production of either soluble or polymeric (lignin) phenolics in crowns.__________Translated from Fiziologiya Rastenii, Vol. 52, No. 3, 2005, pp. 366–371.Original Russian Text Copyright © 2005 by Zagoskina, Olenichenko, Klimov, Astakhova, Zhivukhina, Trunova.     

DNA methylation and histone deacetylation regulating insulin sensitivity due to chronic cold exposure

In this study, we investigated the causal relationship between chronic cold exposure and insulin resistance and the mechanisms of how DNA methylation and histone deacetylation regulate cold-reduced insulin resistance. 46 adult male mice from postnatal day 90–180 were randomly assigned to control group and cold-exposure group. Mice in cold-exposure group were placed at temperature from -1 to 4 °C for 30 days to mimic chronic cold environment. Then, fasting blood glucose, blood insulin level and insulin resistance index were measured with enzymatic methods. Immunofluorescent labeling was carried out to visualize the insulin receptor substrate 2 (IRS2), Obese receptor (Ob-R, a leptin receptor), voltage-dependent anion channel protein 1 (VDAC1), cytochrome C (cytC), 5-methylcytosine (5-mC) positive cells in hippocampal CA1 area. Furthermore, the expressions of some proteins mentioned above were detected with Western blot. The results showed: ① Chronic cold exposure could reduce the insulin resistance index (P < 0.01) and increase the number of IRS2 positive cells and Ob-R positive cells in hippocampus (P < 0.01). ② The expressions of mitochondrial energy-relative proteins, VDAC1 and cytC, were higher in cold-exposure group than in control group with both immunohistochemical staining and Western blot (P < 0.01). ③ Chronic cold exposure increased DNA methylation and histone deacetylation in the pyramidal cells of CA1 area and led to an increase in the expression of histone deacetylase 1 (HDAC1) and DNA methylation relative enzymes (P < 0.01). In conclusion, chronic cold exposure can improve insulin sensitivity, with the involvement of DNA methylation, histone deacetylation and the regulation of mitochondrial energy metabolism. These epigenetic modifications probably form the basic mechanism of cold-reduced insulin resistance.