几丁质及脱乙酰几丁质的微生物降解作用

几丁质及脱乙酰几丁质的微生物降解作用王士奎,王汉潜（廊坊师范专科学校生物系,河北廊坊１０２８４９）氨基糖（ＡｍｉｎｏＳｕｇａｒ）在自然界中主要以多糖（几丁质、肽聚糖、糖蛋白、粘多糖等）形式存在。其中,几丁质作为多数真菌和无脊椎动物的主要结构成份,在自...     

微生物产几丁质酶的研究和应用进展

从产几丁质酶的微生物类群生态分布及微生物产几丁质酶的种类、理化性质等方面论述了微生物产几丁质酶的研究进展。着重论述了提高微生物产几丁质酶能力的方法。介绍了微生物产几丁质酶在植物病虫害防治中的应用进展 ,尤其是微生物产碱性几丁质酶在害虫防治中的增效作用。     

几丁质酶及其研究进展

本文从几丁质酶的分布、发育调节、可诱导性、分子生物学及抗病基因工程等方面近年来的进展进行了综合论述,并对其进一步的应用提出展望。     

几丁质酶的研究进展

几丁质是自然界中含量仅次于纤维素的第二大类多糖,已从各种细菌、真菌、植物、哺乳动物和昆虫中分离并鉴定出来。随着近年来对几丁质及其衍生物的了解,发现此类多糖的物理化学特性在现实中有非常广泛的应用。几丁质酶是一类分解几丁质的酶,广泛分布于细菌、真菌、植物、哺乳动物、昆虫等物种中,并发挥着重要作用。近年来国内外工作者对这些不同来源的几丁质酶做了深入研究,为其在医学和农业上更广泛的应用提供理论基础。     

几丁质酶抑制剂的研究进展

几丁质和几丁质酶在工农业、环保、医药、食品等行业具有广泛的用途。几丁质酶抑制剂是指一类能特异性地与几丁质酶结合,并对几丁质酶产生抑制作用的化合物分子。研究几丁质酶抑制剂,不仅对于深入研究几丁质酶的结构与功能,而且还可能为发现新型的几丁质酶抑制剂提供依据,并为杀菌剂、杀虫剂、化疗药物等的发展提供新的导向。     

昆虫几丁质酶及其在害虫防治中的应用

几丁质是昆虫重要的结构性组分,在昆虫生长发育的各个时期都需要一定量的几丁质来维持其代谢平衡.昆虫几丁质酶可以降解昆虫体壁和围食膜中的几丁质,作为一种潜在的生物杀虫剂在害虫防治方面具有广阔的应用前景.随着对昆虫几丁质酶研究的不断深入,目前已克隆到了30余种昆虫几丁质酶,并应用于转基因作物和基因工程微生物中,对害虫具有一定...     

谈谈植物中的几丁质酶

几丁质酶及其底物几丁质均广泛存在于自然界.由于几丁质酶及其降解产物在生物学、医学、化学、农业及环境科学等方面的潜在价值而越来越受到重视.着重介绍了几丁质酶的作用原理,植物的几丁质酶基因,植物中几丁质酶的特性以及几丁质酶在植物中的作用和在转基因植物中的应用.     

几丁质合酶在人类致病真菌中的研究进展

抑制真菌细胞壁的合成常作为防治真菌感染的安全有效手段。几丁质是真菌细胞壁及隔膜的重要结构成分，几丁质合酶是催化几丁质合成的关键酶。真菌细胞中几丁质合酶家族的不同成员在调控几丁质的合成中存在着差异，因此产生不同的生物学效应。本文通过综述几丁质合酶在人体三大条件致病真菌白色念珠菌、烟曲霉、新生隐球菌中的研究进展，分析了几丁质合酶对真菌致病性影响的机制，总结了几丁质合酶调控真菌细胞增殖、形态转换、病原菌与宿主的相互作用和细胞壁损伤诱导的补偿效应，展望了抗真菌感染的新策略及关于真菌几丁质合酶的未来研究方向。     

昆虫几丁质酶及其在植物抗虫品种改良中的应用

几丁质是昆虫外壳和围食膜的重要组成成分 ,在适当的时期昆虫分泌适量的几丁质酶降解几丁质以保证昆虫的正常生长。植物几丁质酶能够抵御病原菌的入侵 ,但是对昆虫没有明显的效果 ,而昆虫几丁质酶基因在转基因植物中的组成型表达却对昆虫具有明显的抗性。本文综述了昆虫几丁质酶的特性 ,阐述了昆虫几丁质酶及其在植物抗虫方面应用的研究进展。     

果实膨大期喷布磷酸二氢钾对三月红荔枝果实贮藏性的影响

在三月红荔枝(Litchi chinensis cv.Sanyuehong)果实膨大期对树冠喷施0.2%磷酸二氢钾(KP)水溶液,以探讨磷酸二氢钾对荔枝果实贮藏性的影响。结果表明:(1) KP处理的果实在贮藏期前17d,失重率及果肉可溶性固形物、酸、VitC、花色素苷等指标的变化趋势与对照基本相似;(2) KP处理的果肉可溶性蛋白质含量变化与对照有明显差异,而果皮的可溶性蛋白质含量在贮藏期前10d变化动态与对照一致,此后呈相反的变化趋势;(3)果皮POD活性显著高于果肉,KP处理和对照的果肉POD活性在贮藏第3d后、果皮POD活性在第17d前分别具有相似变化趋势;(4)果肉中CAT活性在贮藏第3~17d期间都显著或极显著高于果皮,KP处理和对照果肉、果皮CAT活性动态变化均为单峰曲线。     

Influence of gender on tamoxifen-induced biochemical changes in serum of rats

Tamoxifen, the widely prescribed drug in the prevention and therapy of breast cancer, may cause side effects which may be influenced by gender. The present study was undertaken to investigate the impact of gender on tamoxifen-induced toxic and biochemical changes following oral administration of tamoxifen at high dose level of 20 mg/kg once daily for a 2-week period in both male and female rats. The results showed marked increases in serum activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in female rats. In contrast, treatment with tamoxifen in male animals significantly decreased the activity of ALT, with a tendency for a decrease in serum AST levels. In female rats, a significant reduction in the serum activity of acid phosphatase (ACP) was noted, compared with a non-significant decrease in males. Non-significant changes in serum levels of alkaline phosphatase (ALP) were seen in both sexes. Tamoxifen lowered serum contents of total lipid and total cholesterol in both male and female rats. Serum levels of triglycerides were reduced in female rats as compared to a non-significant decrease in male animals. The serum albumin concentration was decreased in both male and female rats, while total protein was decreased only in female animals. Tamoxifen markedly increased serum levels of creatinine in female rats, compared with a non-significant rise in males. Total serum contents of calcium were similarly reduced in both males and females. This is the first study which points to gender-related differences in tamoxifen-induced toxic and metabolic changes in rats. The results indicated that females are more susceptible than males to tamoxifen toxicity, probably due to the ability of tamoxifen to antagonize the action of estrogen in females.     

Rat brain thioltransferase: regional distribution, immunological characterization, and localization by fluorescent in situ hybridization

Thioltransferase (TTase) is a member of the family of thiol-disulfide oxidoreductases that are involved in the maintenance of sulfhydryl homeostasis in cells by catalyzing thiol-disulfide interchange reactions. One of the major consequences of oxidative stress in brain is the formation of protein-glutathione mixed disulfides (through oxidation of protein thiols), which can be reversed by TTase during the recovery of brain from oxidative stress. We therefore examined the presence of TTase in brain regions from rat. In the rat, TTase activity in the whole brain was comparable with the corresponding activity in liver, but significantly higher in hippocampus. The enzyme activity was significantly lower in striatum and cerebellum compared with activity in whole brain. Rat brain TTase shared immunological similarity with the human red blood cell enzyme, but not with the pig liver enzyme. The constitutive expression of the mRNA to TTase was demonstrable by northern blotting. Localization of the TTase mRNA in rat brain by fluorescent in situ hybridization showed the presence of high amounts of mRNA in the olfactory bulb, cortex, and hippocampus and its predominant localization in the neurons. TTase mRNA was also present in Purkinje cells in the cerebellum, in giant reticular neurons in the midbrain, and in the striatal and thalamic neurons. This study demonstrates the constitutive presence of a functional TTase system in brain and delineates the regional and cellular localization of the enzyme in rat brain.     

羚牛(Budorcas taxicolor)部分脏器特点的观察

本文对2只羚牛的雌性生殖器官及肝、肾、脾等脏器进行了形态描述,并与黄牛及羊的相应器官进行了比较,为探讨羚牛的分类地位提供了解剖学资料。     

Distribution and Abundance of Primates in Rain Forests of the Western Ghats,Karnataka, India and the Conservation of Macaca silenus

We assessed the distribution and abundance of 4 species of diurnal primates viz. lion-tailed macaque, bonnet macaque, Nilgiri langur and Hanuman langur, in 2 areas—Brahmagiri-Makut and Sirsi-Honnavara—in rain forests of the Western Ghats in the state of Karnataka, India. The Nilgiri langurs in Brahmagiri-Makut and the lion-tailed macaques in Sirsi-Honnavara are the northernmost populations of the 2 species in the Western Ghats. The 2 regions represent changes in ecological zones in the Western Ghats. In Brahmagiri-Makut, Hanuman langurs and bonnet macaques occupy lower elevations whereas Nilgiri langurs live in relatively higher altitudes. Only one group of lion-tailed macaques was in Brahmagiri-Makut. In the forests of Sirsi-Honnavara, 3 species of primates viz. lion-tailed macaque, bonnet macaque and Hanuman langur were in larger numbers throughout the forest. A self-sustainable single population of 32 groups of lion-tailed macaques occurred in Sirsi-Honnavara. Few subspecies of Hanuman langurs exist in the study regions. Due to local hunting practices, the relative abundance of primates in Brahmagiri-Makut is lower than that in Sirsi-Honnavara.     

Carbohydrate metabolism in Musa paradisiaca

Considerable variations exist in the content of glucose, fructose, sucrose, starch and protein and in the activities of enzymes involved in carbohydrate metabolism between different parts of the banana plant (Musa paradisiaca). Sucrose synthetase is present in the highest concentration in rootstock and fruit pulp, and sucrose phosphate synthetase in the pseudostem. The highest ratio of the activity of sucrose phosphate synthetase to sucrose synthetase is found in leaves. Acid invertase is present in leaves, leaf-sheath and fruit pulp and is not demonstrable in rootstock and pseudostem. Neutral invertase activity is high in pseudostem and leaf-sheath. Starch phosphorylase is largely concentrated in fruit pulp and rootstock. The maximum activity of ATP:d-phosphoglucose (ADPG) pyrophosphorylase is found in rootstock. β-Amylase is not demonstrable in rootstock and is largely concentrated in leaf-sheath. Hexokinase is most active in rootstock and the lowest in leaves. Acid phosphatase and alkaline phosphatase activity is highest in fruit pulp and pseudostem. Glucosephosphate isomerase is most active in the rootstock and lowest in the leaves.     

Structure, distribution and physiological functions of ghrelin in fish

Ghrelin was originally purified and characterized in rats and humans as the first identified endogenous ligand of the growth hormone secretagogue receptor. In mammals, ghrelin is mainly produced in the stomach, with minor levels of ghrelin present in the brain and various other tissues. Ghrelin is involved in the regulation of many physiological functions including the regulation of growth hormone secretion and food intake in mammals. The gene and peptide structures of ghrelin have been recently identified in several fish species. As in mammals, ghrelin mRNA is mainly expressed in the gut of fish. Ghrelin is involved in the regulation of a number of physiological functions, including the regulation of pituitary hormone release and the stimulation of food intake in fish. In this review, we wish to provide an up-to-date discussion on the structure, distribution and functions of ghrelin in fish, in comparison to ghrelin in other vertebrates.     

Increase in Extracellular Dopamine in the Striatum During Cerebral Ischemia: A Study Utilizing Cerebral Microdialysis

Unilateral ligation of the left common carotid artery in anesthetized Mongolian gerbils resulted in a steep rise in extracellular dopamine in the ipsilateral striatum in 9 out of 19 animals. Extracellular dopamine was measured by cerebral dialysis in vivo and reached a peak of 0.19 mM at 40 min. At the same time, the level of homovanillic acid fell, whereas the levels of ascorbate and 3,4-dihydroxyphenylacetic acid remained relatively constant. In a separate group of animals studied with a combined dialysis/electrochemistry probe, a rise in the in vivo chronoamperometric signal in three out of six animals correlated with a rise in extracellular dopamine. The number of animals responding in these experiments (roughly 50%) corresponds to the frequency of incompetent Circle of Willis, as well as literature reports of the frequency of signs of stroke in unanesthetized gerbils. These results show a remarkable accumulation of dopamine in extracellular fluid in response to cerebral ischemia. Released dopamine appears to be responsible for the elevated in vivo electrochemical signal previously reported.     

Seasonal patterns in feeding ecology of three small fishes in the Biandantang Lake, China

Feeding ecology of three small fish species, Hypseleotris swinhonis, Ctenogobius giurinus and Pseudorasbora parva was studied seasonally in the Biandantang Lake, a small, shallow lake in central China. Gut length, adjusted for total body length, was significantly higher in spring than in other seasons for all the three species. Seasonal changes in gut length were not associated with changes in food quality. Weight of fore-gut contents, adjusted for body weight, was significantly higher in winter and spring than in summer and autumn in H. swinhonis and C. giurinus , and significantly higher in autumn than in spring and summer for P. parva. Percentage of empty fore-guts was highest in summer and lowest in spring for H. swinhonis and C. giurinus , and highest in winter and lowest in autumn for P. parva. Diet of the three small fishes showed apparent seasonal changes, and these changes reflected partly the seasonal fluctuations of food resources in environment. Diet breadth was high in winter and low in autumn for H. swinhonis , high in winter and low in spring and summer for C. giurinus , and high in autumn and low in spring for P. parva. Diet overlaps between pairs of species were biologically significant in most cases, except between H. swinhonis and P. parva in summer and autumn and between C. giurinus and P. parva in autumn.     

Influence of litter and weather on seedling recruitment in a mixed oak-pine woodland

The effects of regular litter removal and annual variation in temperature and precipitation on seedling recruitment of species differing in their seed size and mode of dispersal were studied in a 16-year (1984-1999) experiment in a mixed oak-pine wood in southern Poland. Litter was the most important factor in determining spatial variability in seedling recruitment, whereas differences in climatic conditions among years, especially temperature fluctuations in late winter and early spring, determined the temporal variability in seedling recruitment. Compared with control plots, significantly more new individuals of bryophytes and seedlings as well as a number of new species of vascular plants were noted in the litter-removal plots over the 16-year study. Litter strongly impeded seedling emergence of small-seeded species. The negative effect of litter on seedling recruitment of large-seeded species and the recruitment of new shoots in species growing clonally was much weaker. There was a significant positive correlation between the numbers of seedlings in the litter-removal and control plots and temperatures in January to March. In the litter-removal plots this mainly affected small-seeded species. Seedling recruitment was less consistently related to variation in precipitation. Positive relationships were found only between the number of seedlings of large-seeded species in the litter-removal plots and precipitation in July of the current year and in September of the previous year, and between the number of seedlings in the control plots and precipitation in September and November of the previous year.