A fish-based index for the assessment of the ecological quality of temperate lakes

A fish – based index for the assessment of the ecological quality of natural temperate lakes was developed, in accordance to the requirements of the Water Framework Directive (WFD) 2000/60/EC. As a case study, 11 natural lakes located at northern and western Greece were selected. Fish surveys were conducted during mid summer to mid autumn in 2010, 2011 and 2012 using Nordic gillnets and electrofishing. Environmental parameters and anthropogenic pressures were assessed for each lake. Fish species richness, abundance, trophic, reproductive and habitat functional guilds were used for extracting a set of 107 metrics, meeting the requirements of the WFD. All metrics were initially tested as candidates for the index development. A stepwise linear regression of each metric against environmental parameters (lake area, altitude, maximum depth, alkalinity) and anthropogenic pressures (drainage area covered by non-natural land uses – NNLC, water total phosphorus concentrations – TP, Lake Habitat Modification Score – LHMS) was initially conducted for ensuring pressure-response relationships. Reference conditions for each lake were estimated by the hindcasting procedure and the ecological quality for each lake was expressed as the ecological quality ratio (EQR) by a value ranging from 0 (poor quality) to 1 (excellent quality). Two fish fauna metrics, the relative numerical abundance of introduced species (Introduced_a) and the relative biomass of omnivorous species (OMNI_b) were finally extracted as the most significant, responding to LHMS and TP, respectively. The final index was expressed as the mean values of the EQRs of these two metrics. The multimetric fish index presented herein could serve as a tool for assessing the ecological quality of natural lakes at broad geographical scale and generally, in the Mediterranean temperate lakes with similar hydromorphological characteristics.     

鱼类免疫因子的母体传递及其对子代的保护作用

母源性免疫即母体传递给子代的免疫力。动物在个体发育早期不具备或仅具备极其有限的免疫应答能力,它们主要依靠母源性免疫来抵抗各种病原微生物的攻击。研究表明, 哺乳动物在出生前可以把抗体直接传递给胚胎。       

赣西北溪流鱼类区系组成及其生物地理学特征分析

赣西北地区包括幕阜山脉东南面, 九岭山南北两侧以及鄱阳湖平原之西的广大山区和丘陵地区(图1), 位于E113°55′—116°08′、N28°10′—29°56′。北临湖北、西近湖南、东濒鄱阳湖, 南、北、西三面环山, 中部丘陵起伏。       

复乳法制备红细胞代用品

以单甲氧基聚乙二醇聚乳酸共聚物 [methoxypoly(ethyleneglycol) poly DL lactide,PELA]为膜材 ,用W /O/W的复乳 溶剂扩散法制备了包埋牛血红蛋白 (bovinehemoglobin ,BHb)的微胶囊作为人造红细胞。研究发现复乳过程搅拌分散速率、有机溶剂种类和固化方法对BHb活性有明显影响。当搅拌分散速率小于 90 0 0r/min、以乙酸乙酯为有机相时 ,采用复乳 溶剂扩散法包埋BHb的过程对BHb活性无明显影响。当搅拌分散速率高于 12 0 0 0r/min时 ,BHb活性降低。复乳 溶剂扩散法制备微胶囊过程中固化液体积与微胶囊中BHb活性密切相关 ,通过增大固化液和复乳液的体积比可较好地保持BHb的活性。最后制得了粒径 10 μm左右、包埋率 93%、P50 和Hill系数均接近于天然BHb的微胶囊。     

南方鲇的营养学研究:饲料中大豆蛋白水平对生长的影响

以初始体重为 2 3 .78± 0 .0 9g的南方鲇幼鱼为实验对象 ,在室内循环水养殖系统中进行为期 6周的生长实验。以大豆蛋白分别替代 0 %、1 3 %、2 6 %、3 9%、5 2 %和 6 5 %的鱼粉蛋白 ,配制成 6种等氮 (粗蛋白为 48%)、等能 (总能 2 0 KJ/ g)的饲料 ,用于探讨饲料中鱼粉蛋白与大豆蛋白的不同比例对南方鲇生长及饲料转化率的影响。实验在 2 7.5± 0 .2℃水温条件下进行 ,溶氧维持在 5 mg/ L以上 ,光照周期为 1 4L:1 0 D。实验结果表明 ,当大豆蛋白分别替代1 3 %、2 6 %和 3 9%的鱼粉蛋白时 ,3组之间的特定生长率 (SGR)的差异不显著 (P>0 .0 5 ) ,但均显著高于 5 2 %和 6 5 %替代水平 (P<0 .0 5 )。其中 1 3 %和 2 6 %的替代水平的特定生长率(SGR)显著高于对照组 (P<0 .0 5 ) ;3 9%替代水平的特定生长率 (SGR)与对照组之间差异不显著 (P>0 .0 5 ) ;而 5 2 %和 6 5 %替代水平的特定生长率 (SGR)则显著低于对照组 (P<0 .0 5 )。饲料转化率 (FCE)、蛋白质效率 (PER)和蛋白质累积率 (PPV)分别在各处理组之间的差异关系与特定生长率 (SGR)在各组之间的变化相类似。因此 ,本文提出南方鲇饲料中大豆蛋白替代 3 9%的鱼粉蛋白是适宜的 ,过量的添加将影响南方鲇的生长及饲料转化率。通过分析认为大豆蛋白影响南方鲇生     

用RT-PCR法快速检测鲤春病毒血症病毒基因

用逆转录多聚酶链式反应（RT-PCR）方法快速,灵敏、特异地检测鲤春病毒血症病毒（SVCV）,根据SVC病毒糖蛋白基因序列设计的引物经过RT-PCR和半嵌套PCR（semi-nested-PCR）引扩增出SVC病毒核酸中的714bp和606bp片段,与其他弹状病毒IHNV、VHSV、PFRV没有交叉,没有特异性,灵敏度检测,表明不小于1000个病毒就可检测出阳性结果。本文还对复性温度、引物、Mg^2 、Tag酶以及反转录酶的浓度对检测结果的影响进行了探讨。     

鲤鱼鳃部微环境的pH特征及其对吸附态铜的解吸影响

研究了不同pH条件下鲤鱼（Cyprinus carpio)鳃部微环境pH及CO2的变化情况以及鳃部微环境出水对水铝矿吸附态铜的淋洗效率,结果表明,鱼鳃微环境的平衡pH为8.0,出外环境pH低于或高于该值时,鱼鳃生理作用可以起到缓冲作用,造成鳃部微环境于外环境之间高达0.4个pH单位的差别,CO2含量也表现出相似的变化规律,在碱性条件下,鱼鳃微环境出水对吸附态铜的洗脱效应显著高于pH值相对较高的外环境水。     

Synthetic model and bioactive peptides as potential substrates for enteropeptidase

Summary Enteropeptidase (enterokinase EC 3.4.21.9), catalyzing trypsinogen activation, exhibits unique properties for high efficiency hydrolysis of the polypeptide chain after the N-terminal tetraaspartyl-lysyl sequence. This makes it a convenient tool for the processing of fusion proteins containing this sequence. We found the enteropeptidase-catalysing degradation of some bioactive peptides: cattle hemoglobin beta-chain fragments Hb (2–8) (LTAEEKA) and Hb (1–9) (MLTAEEKAA), human angiotensin II (DRVYIHPF) (AT). Model peptides with truncated linker WDDRG and WDDKG also were shown to be susceptible to enteropeptidase action. Kinetic parameters of enteropeptidase hydrolysis for these substrates were determined.K _m values for all substrates with truncated linker (≈10⁻³ M) are an order of magnitude higher than corresponding values for typical enteropeptidase artificial peptide or fusion protein substrates with full enteropeptidase linker-DDDDK-(K _m ≈10⁻⁴ M).k _cat values for AT, Hb (2–8), WDDRG and WDDKG are ≈30–40 min⁻¹. But one additional amino acid residue at both N-and C-terminus of Hb (2–8) results in a drastic increase of hydrolysis efficiency:k _cat value for Hb (1–9) is 1510 min⁻¹. Recent study demonstrates the possibility of undesirable cleavage of target peptides or proteins containing the above-mentioned truncated linker sequences; further, the ability of enteropeptidase to hydrolyse specifically several biologically active peptidesin vitro along with its unique natural substrate trypsinogen was demonstrated.     

Biases associated with the use of underwater visual census techniques to quantify the density and size-structure of fish populations

Estimates of reef fish densities made by divers visually censusing 5 m wide strip transects were compared with capture-resight estimates calculated independently using data on the resighting frequencies of fish marked with colour-coded tags. The difference in density estimates between methods varied between species but with patterns consistent at the three eastern Tasmanian sites studied. Densities of the two most abundant species, the wrasses Notolabrus tetricus and Notolabrus fucicola, showed good agreement between methods. By contrast, populations of the two monacanthids Meuschenia australis and Meuschenia freycineti were underestimated by an order of magnitude in strip transects relative to capture-resight, while populations of the open-water latrid Latridopsis forsteri were overestimated.For all common fish species observed in strip transects, variation in density estimates between divers was extremely low compared to variation between sites and between months. Variation in density estimates between different days within a week and between 50 m blocks located 50 m apart was also negligible; however, residual error associated with variation by a single diver within a block and day was high. Biases associated with changing detectability of fishes in open versus densely vegetated habitats were assessed by algal removal experiments, and were found to be negligible or non-significantly low for five of the six species examined. The exceptional species—N. tetricus—exhibited a 70% rise in fish sighted by diver following algal clearance despite trapping data indicating no increase in fish numbers.Diver estimates of fish length were on average 7% greater than measured lengths. Divers possessed a clear tendency to make increasingly inaccurate size estimates as fish length deviated in either direction from 300 mm. Lengths of 175-mm animals were underestimated by ≈20% and 400-mm fishes were overestimated by ≈10%. These changes in diver bias with fish size were largely independent of fish species, site and diver. The precision of size estimates, as indicated by the standard deviation of bias, also varied with fish size, with values varying from ≈13% at 200 mm fish length to ≈8% at 400 mm length. The decline in precision at small body size largely reflected size intervals used by divers to bin data. Divers appear capable of making more precise size estimates than the 25-mm interval used at small fish sizes.     

Karyotypic changes associated to the dispersive potential on Pomacentridae (Pisces, Perciformes)

When comparing karyotypic diversification between freshwater and marine fish, a notable increase in modifications associated to the former environment can be noticed in relation to the latter one. This fact is related to the great number of physical partitions (barriers) that exist in continental waters. Furthermore, in the marine environment, the barriers to the gene flow are complex and not always identifiable, especially when considering the participation of dynamic factors such as currents and winds associated to the dispersive potentialities of a living group. Within Perciformes fish, the Pomacentridae family stands out from the others for its intimate relation with the coral reefs, as well as for its diversity of forms and biological characteristics, providing an adequate model for studying the influence of the pelagic period of the larval stage upon the karyotypic evolution. In the present work, cytogenetic analyses were carried out on three Pomacentridae species, typical representatives of the coral reefs, Abudefduf saxatilis (2n=48, FN=52, 2 m+2sm+44a), Microspathodon chrysurus (2n=48, FN=64, 6 m+10st+32a) and Amphiprion frenatus (2n=48, FN=92, 14 m+22sm+8st+4a) that have different pelagic larval periods. The analyses between subfamilies showed a trend that the lower the dispersive potential, the greater the quantity of fixed pericentric inversions based on the basal karyotype of the Perciformes.