Lactate dehydrogenase isozymes in the genus Channa: Species-specific patterns

The lactate dehydrogenase isozyme system for five Channa species (snakehead fish) have been examined by means of polyacrylamide gel electrophoresis. The pattern and distribution of the LDH isozymes in all these species are found to be species-specific with a reversed relative mobility of the A and B subunits as compared to most of the other vertebrates. In addition to these two subunits, an eye-specific LDH E isozyme has also been detected in these species.     

不同光照强度下乌鳢幼鱼的摄食强度及动力学

在103－10－3lx光照强度范围内,乌鳢幼鱼对浮游动物的摄食强度随光照强度的减弱而增强,在10-3lx时达最大值;摄食丰在10-3lx时最高,并随时间的延长而显著降低。     

Influence of size and level of satiation on prey handling time in Channa striata (Bloch)

Channa striata fry (100 ± 20 mg) and fingerlings (2 ± 0.2 g) were offered mosquito larvae as prey and the adults (75 ± 5 g) small fishes. The size of the fish was directly related to satiation time and inversely related to satiation amount. The influence of satiation levels on handling time, showed an increase to almost eight-fold in fry and fingerlings and about two-fold in adults. The study also revealed the role played by the young of C. striata in mosquito control. With the increase in size of the fish the preference for mosquito larvae was seen to decrease. The air breathing habit and hence its ability to survive in polluted and oxygen-depleted waters makes it a suitable candidate as a fish for mosquito control.     

Seasonal reorganization of nitrogen metabolism in an Indian air-breathing teleosts,Channa punctatus (Bloch)

Channa punctatus, an air-breathing freshwater teleost, mobilizes more protein for its energy requirement during summer and spawning months, as revealed by the data on endogenous nitrogen excretion in the form of ammonia-N, urea-N, free amino acids, creatinine and creatine.     

Evidence of geographical structuring in the Malaysian Snakehead, Channa striata based on partial segment of the CO1 gene

Channa striata, locally known as "haruan", is economically important in fisheries and aquaculture industries in several Asian countries. DNA sequencing, based on a partial segment of the Cytochrome oxidase c subunit 1 (CO1) gene, was used to determine genetic variation in C. striata samples from four different populations on the west coast of Peninsular Malaysia. The highest nucleotide and haplotype diversities were observed in the Linggi population (π = 0.0067, h = 0.835), and the lowest in the Timah Tasoh population (π = 0.0008, h = 0.286). Apart from Kajang-Linggi, which was insignificant, F(ST) values were significant (p < 0.05) in all pairwise-population comparisons. Consequently, it is inferred that genetic structuring C. striata populations in this region was largely shaped by a common origin, with secondary influences from geographical factors and isolation.     

Genetic structure of the snakehead murrel, Channa striata (channidae) based on the cytochrome c oxidase subunit I gene: Influence of historical and geomorphological factors

Nucleotide sequences of a partial cytochrome c oxidase subunit I gene were used to assess the manner in which historical processes and geomorphological effects may have influenced genetic structuring and phylogeographic patterns in Channa striata. Assaying was based on individuals from twelve populations in four river systems, which were separated into two regions, the eastern and western, of the biodiversely rich state of Perak in central Peninsular Malaysia. In 238 specimens, a total of 368-bp sequences with ten polymorphic sites and eleven unique haplotypes were detected. Data on all the twelve populations revealed incomplete divergence due to past historical coalescence and the short period of separation. Nevertheless, SAMOVA and F(ST) revealed geographical structuring existed to a certain extent in both regions. For the eastern region, the data also showed that the upstream populations were genetically significantly different compared to the mid- and downstream ones. It is inferred that physical barriers and historical processes played a dominant role in structuring the genetic dispersal of the species. A further inference is that the Grik, Tanjung Rambutan and Sungkai are potential candidates for conservation and aquaculture programmes since they contained most of the total diversity in this area.     

鰤鱼诺卡氏菌对乌鳢血液指标的影响

应用浓度为106cfu/mL的鰤鱼诺卡氏菌(Nocardia seriolea)菌悬液腹腔注射乌鳢,人工感染诺卡氏菌病。在感染后3d、6d、9d、12d、18d和24d时抽取乌鳢血液,检测乌鳢的血细胞数、血细胞脆性、溶菌酶、血清总蛋白、碱性磷酸酶、乳酸脱氢酶和尿素氮等指标。结果表明,与对照组相比,感染鰤鱼诺卡氏菌后乌鳢血细胞数呈先升高后降低的趋势,而血细胞脆性在各实验时间点均高于对照组;血清碱性磷酸酶呈先降低后升高趋势,血清溶菌酶、血清总蛋白和血清尿素氮等均呈先降低后增高再降低的趋势,血清乳酸脱氢酶活力显著增加。说明鰤鱼诺卡氏菌感染会引起乌鳢血液指标明显变化。     

三个种群有尾和断尾丽斑麻蜥的选择体温、表面活动和摄食量

用2006年4-6月捕自长安(陕西)、共和(青海)、哈尔滨(黑龙江)三个地理隔离种群尾部完整的丽斑麻蜥(Eremias argus)成年雄体检测断尾对选择体温、表面活动(表面调温个体数)和摄食量的影响。各种群个体均分为实验和对照组,在距尾基部10 mm处切除实验组蜥蜴尾部,获得断尾个体。实验和对照组个体饲养在相同的实验室条件下收集相关数据,历时四周。表面活动的种群间差异是不同种群个体对其所处区域热环境长期适应的结果。断尾个体减少表面活动见于所有三个种群,表明尾自切能导致丽斑麻蜥活动水平的改变。同一种群断尾和有尾个体表面活动的时间格局无显著差异,不同种群表面活动的时间格局无显著差异,这些结果表明丽斑麻蜥白天活动节律具有种的特异性,不受断尾影响。丽斑麻蜥选择体温随纬度或海拔升高而降低,这种变化趋势可能是热环境制约的结果。所有三个种群断尾个体的选择体温均低于有尾个体,表明断尾可改变丽斑麻蜥的体温调定点。丽斑麻蜥摄食量存在种群间差异,长安种群蜥蜴的摄食量显著大于共和种群蜥蜴。三个种群断尾个体均未增加摄食以满足尾再生的额外能量需求,表明增加摄食不是该种蜥蜴补偿断尾能量代价的对     

Structure and composition of teleost scales from snakehead Channa argus (Cantor) (Perciformes: Channidae)

The structure of teleost scales from snakehead Channa argus was investigated using thermogravimetric analysis (TG), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive analysis of X-rays (EDAX), Fourier transform infra-red spectroscopy (FTIR) and X-ray diffraction (XRD). Thermal treatment of fish scales indicates that the fibrillary plate is partially calcified. SEM shows two kinds of scale denticles, arranged along the circuli in the anterior field and the lateral fields, respectively. TEM indicates the stratum laxum with abundant fibrils, chromatophores and capillary blood vessels within the scale covering, and shows the fibrillary plate as an 'orthogonal plywood structure' of stratified lamellae, consisting of 80–100 nm diameter collagen fibres co-aligned in individual lamellae and alternated by c. 90° of the fibre alignment between adjacent lamellae. EDAX, FTIR and XRD show that the mineral phase of the scales is a carbonated hydroxyapatite with a Ca:P molar ratio of 1·85.     

Argusides D and E, two new cytotoxic triterpene glycosides from the sea cucumber Bohadschia argus Jaeger

Two new triterpene glycosides, argusides D and E (1 and 2, resp.), have been isolated from the sea cucumber Bohadschia argus Jaeger collected in the South China Sea. Their structures have been established by spectral analysis (ESI-MS, and 1D- and 2D-NMR) and chemical evidence. Compounds 1 and 2 both possess an holostane-type triterpene aglycone with a C(9)=C(11) bond, an OH group at C(12), and tetrasaccharide moieties, but differ in the side chains. The two glycosides exhibited significant cytotoxicities against four human tumor cell lines, A549, HCT-116, HepG2, and MCF-7.