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本文以耐旱的牛耳草(Boea hygrometirica)为材料,研究了乙烯合成关键酶之一——ACC氧化酶编码基因(BhACO1)在干旱复苏过程中的诱导表达及其编码蛋白的酶活,分析了乙烯在干旱复苏过程中的积累及其对叶片复苏能力的影响和对干旱诱导基因的调控,探讨了一个受乙烯调控的干旱诱导的引导蛋白编码基因(BhDIR1)的表达及其功能。 利用cDNA微阵列技术从牛耳草干旱2h的叶片中得到一个ACC氧化酶基因片段,经5’-RACE得到全长cDNA,命名为BhACO1。BhACO1包含317个氨基酸,与其它植物中的ACC氧化酶具有80%左右的序列相似性。BhACO1基因受乙烯和干旱诱导、但ACC氧化酶抑制剂氯化钴可抑制其干旱诱导表达。BhACO1基因受ABA、2,4-D、SA、H2O2、CaCl2、EGTA及热害和盐害的诱导,但不受冷害诱导。原核表达的GST-BhACO1融合蛋白在体内体外均表现出ACC氧化酶的活性,而过量表达BhACO1的转基因植物的蛋白提取物也表现出较野生型更强的ACC氧化酶活性。 乙烯在牛耳草叶片干旱复水过程中随着时间延长而逐步积累。外源乙烯可诱导叶片黄化,但不影响叶片在复水后的复苏能力;氯化钴处理可部分地抑制乙烯合成而降低牛耳草叶片在干旱过程中乙烯的释放量,同时导致叶片失去复苏能力。与对照相比,氯化钴处理的叶片在干旱时仍可维持较低的离子渗漏水平,但复水后发生大量离子外渗,表明细胞膜完整性也遭到破坏;光系统ІІ活性下降程度在干旱时与对照相似,但复水后完全丧失。 乙烯诱导牛耳草干旱响应基因BhDohb561,BhLEA2和BhDIR1的表达,但不影响牛耳草干旱响应基因BhCML1,BhGRP1,BhSGP和BhLEA1的表达。除BhLEA1外,上述基因在干旱过程中的诱导表达均可被氯化钴预处理所抑制,尤其是BhSGP最明显。 BhDIR1在牛耳草干旱复水过程中mRNA明显地积累,乙烯、ABA、CaCl2、EGTA、H2O2、SA和热害、冷害、盐害都可诱导其表达。BhDIR1编码一个199个氨基酸的小分子量蛋白质,与松柏等植物中发现的可能参与木质素合成的引导蛋白具有约20-30%的序列相似性。与其它引导蛋白相同,BhDIR1在N’端包含一个外泌的信号肽,GFP定位分析表明BhDIR1定位于细胞膜和壁上。 上述结果表明,乙烯在牛耳草叶片耐脱水复苏反应中有不可或缺的作用,而ACC氧化酶所催化的反应是干旱诱导的乙烯合成中的关键步骤。氯化钴预处理通过抑制干旱过程中的乙烯合成,影响一系列基因的干旱诱导表达导致叶片在生理水平和细胞水平上造成了损伤,或是使牛耳草失去了在复水过程中原有的修复能力而无法恢复生命力。BhDIR1作为乙烯调控的下游靶基因之一,可能通过调控木质素的单体间的连接方式而改变木质素的物理性质来影响细胞壁的机械强度和柔韧性,减少干旱对细胞造成的机械伤害。

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EXTRACT (SEE PDF FOR FULL ABSTRACT): Temperature and lapse rate show extreme departures from mean values for May 1981 through October 1986 at the high-elevation station D1 on Niwot Ridge in the Front Range, Colorado. If the D1 record is accurate, this period may present an opportunity to identify factors that influence temperature at high elevations, but not necessarily at low elevations. This paper focuses on four questions: (1) Is the D1 temperature record accurate? (2) What is the geographical extent of this anomalous cold period? (3) Are there any identifiable contributing factors or physical events relating to this period? (4) Is there evidence of a similar anomalous period in the past?

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Low level aqueous radioactive wastes from the nuclear complex at Trombay are discharged into the Bombay harbour. Of the 6 principal radionuclides comprising the discharge, cesium-137 is most predominantly taken up by silt from the sea water. Isoactivity contours show that activity levels just off the point of discharge, and further south to Pir Pau, were between 50 and 100 pCi/g. Activity in the main channel of the harbour remained below 10 pCi/g, while further north (below the Thane Creek bridge) it was around 20 pCi/g. Activity in the top 6 cm of a core off Trombay naval jetty was <5 pCi/g, reaching a maximum of 178 pCi/g at 14cm below the surface. Thereafter, it tapered off to 5 pCi/g down to a metre.

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The acute toxic effect of the toxicant sumithion (50% E.C.) on mortality rate (after 24, 48, 72, and 96 h), total RBC count and haemoglobin content (after 48 and 72 h) on Heteropneustes fossilis was investigated at four concentrations (9.7, 10.7 and 11.1 ppm). The sumithion treated fishes showed lower RBC and Hb levels than the untreated ones. A gradual decrease in the total RBC counts and Hb contents was recorded with increasing concentration of toxicant after 72 h but the blood showed fluctuating values after 48 h of treatment.

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A 10-weeks culture trial of mud crab, Scylla serrata in brackish water earthen pond was conducted in different stocking densities. The aim of the experiment was to identify a suitable stocking density for optimum production. There were three treatment as 5000 crab lings/ha, 10000 crab lings/ha and 15000 crab lings/ha of each with three replications. The initial mean weight of crab lings were same (5.5 ± 0.13 g). The experimental month was June '95 to August '95. The size of each pond was 500 m². To maintain good water quality water was exchanged in every spring tide. The salinity during the experiment were 2-18ppt. Prepared feed of about 32% protein consisting fish meal, MOC rice bran and wheat flour was used at 5% of their body weight. In terms of production, survival rate, growth and carapace width, the stocking density having 10000/ha showed the best (P

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Comparative impact of chloral hydrate anaesthesia on the metabolic rate of Indian major carp Labeo rohita and larvivorous fish Poecilia reticulata was assessed. Observation on the Oxygen Consumption Rate (OCR) revealed that in common guppies OCR was substantially low (1.105 and 1.097 mg/g/hr) at 0.1 and 0.25 g/l concentrations of chloral hydrate as against OCR of 1.487 mg/g/hr in the control. Fry of L. rohita in group showed lower metabolic rates in the control as well as treated conditions as compared to the individuals of this fish. This may be due to sympathetic psychophysiological reflex of grouped fish. Higher dose of chloral hydrate (0.25 g/l) also caused higher OCR probably due to distress. Application of chloral hydrate also favoured lesser release of metabolic wastes (ammonia and carbon dioxide). There was significant positive correlation between time and oxygen consumption, whereas, for time and OCR this relationship was negative. Regression of chloral hydrate doses for OCR and time has also been calculated.

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The present study on growth rate of different body parts in relation to total length, in the male and female Puntius sarana (Ham.) did not show any significant heterogeneity except in snout length (p.01). The growth rate of snout length was found to be higher in females (b=0.0377) than in males (b=0.0266). Since the growth rate of most of the body parts was found to be homogeneous in both the sexes, the common regression co-efficient "b" was calculated on pooled data to represent the growth rate of different body parts against total length, the linearity of regression lines indicated isometric growth.