大鼠心脏血压超负荷诱导左心室HSP70基因表达

本工作应用热休克蛋白７０（ＨＳＰ７０）核酸分子杂交方法,测定了大鼠腹主动脉缩窄后左心室ＨＳＰ７０ｍＲＮＡ的水平。结果表明：大鼠腹主动脉缩窄后４ｈ,动脉血压已明显升高,并持续在高水平上;大鼠左心室重／体重比在第三天开始增加,然后持续升高,第４周时比对照组增加５９％;左心室ＨＳＰ７０ｍＲＮＡ在腹主动脉缩窄后４ｈ已明显升高,１ｄ,２ｄ,１ｗ均维持在高水平,１ｗ后逐渐消失。实验结果提示：大鼠心肌负荷增加早期,左心室ＨＳＰ７０ｍＲＮＡ表达明显增加。     

Thermodynamics of ubiquitin unfolding

The energetics of ubiquitin unfolding have been studied using differential scanning microcalorimetry. For the first time it has been shown directly that the enthalpy of protein unfolding is a nonlinear function of temperature. Thermodynamic parameters of ubiquitin unfolding were correlated with the structure of the protein. The enthalpy of hydrogen bonding in ubiquitin was calculated and compared to that obtained for other proteins. It appears that the energy of hydrogen bonding correlates with the average length of the hydrogen bond in a given protein structure. © 1994 John Wiley & Sons, Inc.     

葡萄试管苗热处理结合茎尖培养脱病毒效果的研究

对７个生食葡萄品种的试管苗热处理结合茎尖剥离培养脱除病毒的方法做了研究,结果表明,从热处理试管苗剥离的茎尖培养成活率为６１．２％,其中有１８．１％的成苗。各品种热处理试管苗剥离的茎尖分化再生能力不同：先形成愈伤组织的成苗率较低,而先分化芽的茎尖成苗率较高。这一方法对扇叶病毒和卷叶病毒的脱除率达９２％以上。     

Estimating transpiration from 6-year-old Eucalyptus grandis trees: development of a canopy conductance model and comparison with independent sap flux measurements

Daily patterns of stomatal conductance (g_s), xylem pressure potential (P) and canopy microclimatic variables were recorded on 11 sample days as part of a one-year study of the water use of Eucalyptus grandis Hill ex Maiden in the eastern Transvaal, South Africa. Measured g_s was found to be largely controlled by quantum flux density (Q) and ambient vapour pressure deficit (D). Canopy conductance (g_c) was determined for hourly intervals using g_s measurements and leaf areas in four different canopy levels. A simple model was constructed to allow the prediction of g_c and transpiration from Q, D and season of year. The model was used to estimate transpiration rates from 10 trees in a later study of similarly-aged E. grandis trees, in which sap flow in each tree was measured using the heat pulse velocity (HPV) technique. Five of the trees were monitored on a summer day and five on a winter day. Correspondence between HPV sap flow and modelled transpiration was good for the summertime comparisons, but measured winter-time sap flow rates were underestimated by the model, especially under conditions of high sap flow. The discrepancy is believed to result from having insufficient data from the conductance study to describe the response of g_s to relatively high D in winter. Marked variation in transpiration per unit leaf area indicates that a relatively large number of trees must be sampled for the HPV technique to be used to obtain a mean rate for an entire stand in winter.     

Expression of heat shock proteins during development of barley

Barley heat shock proteins have been cloned, characterized by hybrid release translation and sequenced. Clones coding for proteins of 17, 18, 30, 32 and 70 kDa have been obtained. Out of these the 32 and 30 kDa proteins have been characterized as precursors to plastidic proteins of 26 kDa by posttranslational transport and by cDNA sequencing. The coding regions of these two transcribed genes are highly homologous. Accumulation of the plastid HSP as well as of HSP 70 as well as their corresponding mRNAs has been studied in 2- to 6-day old seedlings and in the 7-day old barley leaf. The mRNA for all investigated proteins were only found after a heat shock; the mRNA levels increase towards the tip of the leaf and with development. Furthermore, under the conditions used the mRNAs for all investigated heat shock proteins accumulate in parallel. Unexpectedly, both proteins, HSP 70 and HSP 26, are found by western blotting in the 2-day old control plants in the absence of any inducing heat shock. At later stages of development and in the leaf gradient only immunoreactivity with HSP 70 was observed. In contrast to the levels of their mRNAs the highest levels of HSP 30–26 and 70 have been observed in the basal segments indicating that translational control plays a role during HSP expression. Under severe heat shock a protein of 30 kDa is induced whose identity is not known but which reacts with the antibody to HSP 30–26 and might represent the accumulating precursors of the plastidic proteins.     

Transient expression of GUS and anthocyanin constructs in intact maize immature embryos following electroporation

Electroporation was used for the delivery and subsequent expression of GUS and anthocyanin reporter genes into intact maize immature embryos. The optimal conditions consisted of culturing immature embryos for 4 days on N6 1-100-25-Ag medium prior to electroporation (375 V/cm; 960 µF capacitance) in EPR buffer containing DNA and 0.07 M sodium glutamate at room temperature (22°C) after a 10 min heat shock at 37°C. Under these conditions, over 40 spots of GUS transient activity were observed per immature embryo. Transient gene expression after electroporation was further demonstrated using an anthocyanin construct, which is specific for expression in plant cells.     

Annual survival rate and age structure of habu,Trimeresurus flavoviridis (Viperidae), on Minna island,Japan: Estimation from removal trapping

A population of a viperid snake,Trimeresurus flavoviridis, was studied over 10 years by removal trapping on a small subtropical island in Japan. The sex ratio of trapped individuals changed seasonally, but was not biased to either sex in the whole sample of 258 individuals. The age of each individual was estimated through the size structure and the age-size relationship. The minimum number of individuals at the beginning of the study was estimated through accumulating older individuals trapped in the subsequent years. By assuming an annual natural survival rate in the course of this accumulation, an age structure was simulated which led to calculate a resulted natural survival rate. The assumed rate of 0.62 fitted best to the resulted one. The annual trapped proportion estimated on the simulated absolute number of individuals was higher in older individuals than in younger ones with the overall mean of 16%.     

Postharvest disease control in mangoes using high humidity hot air and fungicide treatments

The disease control efficacy of quarantine heat treatments developed for fruit fly disinfestation in mangoes cv. Kensington Pride was evaluated in this study. Heat was applied using high humidity (>95% r.h.) hot air (HHHA) at temperatures ranging from 47–49°C. Anthracnose, caused by Colletotrichum gloeosporioides, was well controlled in mangoes heated to a core temperature of 46°C, 47°C or 48°C for 24, 10 or 8 min respectively, prior to ripening at 23°C for 16 days. Stem end rot, caused by Dothiorella dominicana and Lasiodiplodia theobromae, was not satisfactorily controlled by these treatments. In a subsequent experiment, fruit were immersed in a hot benomyl (0.5 g a.i. litre“¹ at 52°C for 5 min) or unheated prochloraz (0.25 ml a.i. litre¹ at 28°C for 30 s) dip before or after the application of HHHA (core temperature of 47°C for 10 min). During storage at 23°C for 15 days, the incidence of stem end rot was reduced by HHHA alone, although immersion in hot benomyl either before or after HHHA treatment greatly improved stem end rot control. HHHA treatment (core temperature of 46.5°C for 10 min) alone reduced the incidence of anthracnose in mangoes stored at 13°C for 14 days prior to ripening at 22°C, although a combination treatment consisting of HHHA and either hot benomyl or unheated prochloraz gave complete control of anthracnose under these storage conditions. HHHA treatment alone gave no control of stem end rot in mangoes stored at 13°C prior to ripening at 22°C. A supplementary hot benomyl treatment was required for acceptable control of this disease in cool-stored mangoes. The development of yellow skin colour in fruit was accelerated by HHHA treatment.