996 resultados para Biochemical variation


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In order to understand how mandibular structure differs among the Chinese cercopithecoids (Rhinopithecus, Trachypithecus and Macaca), particularly the uniqueness of the snub-nosed monkeys (Rhinopithecus), we analysed ten mandibular measurements by principal components analysis (PCA), and examined scaling patterns. The results provided by the PCA illustrated differences due to size among the cercopithecoids and the relationship between colobines (Trachypithecus and Rhinopithecus) and cercopithecines, in which macaques (Macaca) are included. Allometric analysis indicated that, biomechanically, there is not a marked difference between macaques and leaf-eating monkeys. This may be associated with the fact that both share some similar ecology and niches in south and southwest China. The snub-nosed monkeys exhibit a significantly more robust mandible, evident in the symphysis, corpus, condyle, and masticatory momentum arm. This supports the hypothesis, based on the study of dental structure, that Rhinopithecus is a unique group in Asian Old World monkeys (OWMs) and has developed some unique characteristics in order to adapt to the tough food available in the severe cold climate of the Plateaux of Qinghai-Tibet, Yun-Gui and Qingling in China.

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Objectives included measuring genetic variation and population structure of Indian mackerel (Rastrelliger kanagurta) in order to ascertain whether current exploitation is sustainable. .

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A sample of 114 specimens of Dremomys pernyi was investigated, 73 of which had intact skulls and were subjected to multivariate, coefficient of difference (C. D.), and cluster analyses. Results indicate that 4 subspecies (groups) of Dremomys pernyi inhabi

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A total of 66 specimens of Niviventer andersoni with intact skulls was investigated on pelage characteristics and cranial morphometric variables. The data were subjected to principal component analyses as well as to discriminant analyses, and measurement

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In a number of recent studies, we summarized the obvious errors and shortcomings that can be spotted in many (if not most) mitochondrial DNA (mtDNA) data sets published in medical genetics. We have reanalyzed here the complete mtDNA genome data published

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To determine the origin and genetic diversity of Chinese cattle, we analyzed the complete mtDNA D-loop sequences of 84 cattle from 14 breeds/populations from southwest and west China, together with the available cattle sequences in GenBank. Our results sh

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The aim of this study was to characterize the genetic diversity of domestic goat in China. For this purpose, we determined the sequence of the mitochondrial DNA (mtDNA) control region in 72 individuals of the Yangtze River delta white goat, and reanalysed

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对云南轿子雪山自然保护区地表甲虫物的种组成及生物多样性季节变化进行了连续跟踪调查.调查结果如下:(1)通过对4种典型微环境样地(草地、灌丛、林地以及农田生态系统)连续3次跟踪连续调查,共获得标本2451头,分别隶属于24科.其中步甲科(Carabidae)为优势类群,占总数的62.10%;隐翅虫科(Staphylinidae)其次,占12.77%.可能由于海拔、气温等因素影响,该地区昆虫活动高峰期较短.(2)通过对4种典型微生态环境中地表甲虫的生物多样性的比较,表明不同生境内甲虫的多样性指数存在动态变化,在不同生境片区内甲虫存在迁移活动,甲虫多在灌丛中越冬,并随季节及食物源迁移.

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The ribbon fishes ‘of the family Trichiuridac are represented as one of the most important food resources in Indian ocean. High density of the dominant species of ribbon fish (Trichiurus lepturus) in Oman sea and the 'Tillable catch in last yeas (more than 7000 tones per year) makes a trust area for studing their population biolog and stock assessment. As our knowledge on reproductive biology of this species has an important role on their fisheries management, as well as conservation of this stock from decline or over fishing, this research was held to determine some aspects of reproductive physiology of ribbon fish and the effects of environmental factors in gonadal cycle. The goals of the present thesis is to determine some aspects of reproductive physiology such as gonadosomatic index (GSI) , hepatosomatic index (HSI), condition factor (Ko, fecundity, sex ratio, size at first maturity, size at maturity (LM5O) and their relative hormonal & biochemical fluctuations. In this regards annual variation of sex hormones ic. estradiol 17-B, progestron, cortisol, testostrone and gonadotropins FSH (GTH-I) , LH (GTH-ll)I were measured ; gonadal histological studies were done by light & electron micrography. The research was carried out from April 1995 to January 19% in Ras Nleidani in the north part of Oman sea, and the environmental factors such as temperature, salinity, oxygen, rainfall and pH were measured. The effects of these parameters on reproductive cycle and hormonal fluctuationswere discussed by using correlation and principle component analysis (PCA). Female Ribbon fish reproductive strategy shows the same paterns of nonguarder marine teleosts. T. lepturus has more than one spawning season (existance of egges in different size in each month) and therfore it must have asynchronous ovaries and belong to continious spawners. GSI and HSI are good evidences for this type of reproductive patern. The testis of the lobular type , which is typical of most teleosts , is composed of numerous lobules which are separated from each other by a thin layer of fibrous connective tissue. GSI fluctuations revealed prolong- spawning time in males. There is significant increase in 17-13 estradiol. progestrone , cortisol and gonadotropins with maturity and prespawning period of female T lepturus. Plasma concentration of E2 and GTH II incresaed along with water temperature increasing (3300).. Spawning was observed from Nov. 1995 to Apr. 1996 in this species. Progestrone increased significantly with increasing rainfall in this season (P<0.01). Plasma cortisol levels increased with maturation and vitelpgenesis and also with the peak of spawning. From lenght-weight frequency and size distribution in each age groups and also minimum size at first maturity (52a cm) it would he concluded that T. lepturus must be matured at 2 years of age. Serum cholestrol and triglicerides significantly increased when maturation occured in this species. The relationship between alkaline phosphatase activity and hormonal fluctuations with maturity and vitelogenesis were discussed. Proximate compostion (muscle) shows significant variation with spawning period and maturity. Absolute individual fecundity (17420-159150) increased with body length and weight. Ultrastructural observations show dramatic variation in cell membrane (0ocyte membrane), yolk vesicles and, nucleolus dispersal in relation to maturity stages. fluctuations of gonadal hormones were discused in relation with vitelogenesis. Testosterone increased in males from Nov: to Mar. due to environmental impacts and spawning time. Sex ratio in different depth (10-40 m ,80-110 m) shows significnt differences in this ratio for two depths. In 10-40 m depth female shows dominant abundance to male in each months that may be due to their reproductive migration behaviour. The effects of temperature photoperiod and rainfall to maturity and spawning were discussed. According to -pawning period of T. leptunts in our sampling area it could be suggested that ribbon fish fi,theries must be restricted in the peak of spawning seasons (Feb. to Mar.) and in the spawning grounds (under 40 m depths). Other suggestions for population conservation have been mentioned.

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Motor task variation has been shown to be a key ingredient in skill transfer, retention, and structural learning. However, many studies only compare training of randomly varying tasks to either blocked or null training, and it is not clear how experiencing different nonrandom temporal orderings of tasks might affect the learning process. Here we study learning in human subjects who experience the same set of visuomotor rotations, evenly spaced between -60° and +60°, either in a random order or in an order in which the rotation angle changed gradually. We compared subsequent learning of three test blocks of +30°→-30°→+30° rotations. The groups that underwent either random or gradual training showed significant (P < 0.01) facilitation of learning in the test blocks compared with a control group who had not experienced any visuomotor rotations before. We also found that movement initiation times in the random group during the test blocks were significantly (P < 0.05) lower than for the gradual or the control group. When we fit a state-space model with fast and slow learning processes to our data, we found that the differences in performance in the test block were consistent with the gradual or random task variation changing the learning and retention rates of only the fast learning process. Such adaptation of learning rates may be a key feature of ongoing meta-learning processes. Our results therefore suggest that both gradual and random task variation can induce meta-learning and that random learning has an advantage in terms of shorter initiation times, suggesting less reliance on cognitive processes.

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Invertebrates are some of the key food items for fish diets. They thus form an important fish food environment upon which the fisheries thrives in terms of production through dietary support. Invertebrates communities of Lakes Albert and Kyoga have been evaluated and considered the implications for diets and production of commercial fishes.

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To investigation of the toxic effects of atrazine on newly hatched larvae and releasing age fry of the Caspian Kutum, Rutilus frisii kutum, the 96h LC50 was determined as 18.53 ppm and 24.95 ppm, respectively. Newly hatched larvae were exposed to three sublethal concentrations of atrazine (1/2LC50, 1/4LC50 and 1/8LC50) for 7 days. Different histopathological alterations were observed in fins and integument, gills, Kidney, digestive system, liver and the brain of the exposed larvae. Fry’s were exposed to one sublethal concentration of atrazine (1/2LC50) for four days, and like the larvae’s, many histopathological alterations were observed in fins and integument, gills, Kidney, digestive system, liver and the brain of the exposed fry’s, too. Also, measurements of the body ions: Na+, K+, Ca2+, Mg2+ and Cl- in atrazine exposed larvae and fry’s compare to control groups showed that atrazine is changed the body ions composition. No significant differences were found in length growth rate, weight growth rate and the condition factor of the atrazine exposed larvae and fry. Immunohistochemical localization of the Na+, K+-ATPase in integumentary and gill ionocytes, showed no differences in dispersion pattern of the ionocytes in atrazine exposed larvae and fry, compare to control group. Measuring the dimensions of the ionocytes and counting the ionocytes showed that atrazine is affecting on ionocytes by mild increasing in size and mild decreasing in number. Ultrastructural studies, using SEM and TEM, showed that atrazine have significant effects on cellular and subcellular properties. It caused necrosis in surface of the pavement cells in branchial epithelium, necrosis in endoplasmic reticulum of the ionocytes and changed the shape of the mitochondria in these cells. Results showed that sublethal concentrations of atrazine were very toxic to larvae and fry of the Rutilus frisii kutum, and at these levels can made some serious histopathological alterations in their tissues. Related to the severe histopathological alterations in osmoregulatory organs, like gill, kidney and digestive system, and the alterations in the body ion composition, it could be concluded that atrazine could interfere with the osmoregulation process of the Rutilus frisii kutum at the early stages of the life history.

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从2000 年11 月至2002 年1 月, 我们在云南富合山(99°20′E , 26°25′N) 记录了滇金丝猴( Rhinopithe2 cus bieti) 的游走以及其他行为, 以描述猴群行为模式的季节性变化及其对温带环境的适应。由于季节间行为方 式的相似, 我们将冬季和春季、夏季和秋季的数据合并表述。猴群终年以取食树叶为主, 多在过夜地附近活动。 在冬- 春季, 猴群一般在低海拔的南部地区活动, 同时缩短日行走距离, 花费较多的时间取食树叶、竹叶和竹 笋; 而在夏- 秋季猴群的活动模式与冬- 春季相反, 并取食大量果实。我们将富合地区猴群的季节性游走模式 以及食性看作是食物供给和温度变化之间折中的结果, 这些行为特征和其它温带灵长类的相似。此外, 过夜地 的分布也会影响猴群利用家域内各方格的方式[动物学报50 (5) : 691 - 696 , 2004 ] 。