南极磷虾生物活性物质的研究进展

南极磷虾因其生活环境和方式的特殊性而具有产生新型生物活性物质的巨大潜力,也因其巨大的生物资源量和潜在的渔业价值而日益受到人们的重视。南极磷虾生物活性物质包括酶、脂质、甲壳素、生物活性肽和紫外吸收物质等。本文综述了南极磷虾生物活性物质的研究进展,并展望了南极磷虾生物资源开发利用的前景。     

南极磷虾种群生物学研究进展 Ⅱ繁殖

南极磷虾通常是指南极大磷虾(Euphausia superba Dana, 1852)(下简称大磷虾), 平均寿命35年, 个体最大体长可达65 mm, 体重达2 g 1, 2。大磷虾数量巨大, 已成为重要的商业性渔业资源, 年可捕量可达0.32亿 吨1, 3, 渔业捕捞的主要磷虾群体为体长介于4065 mm的较大成体。考虑到该种在南极食物网中所起到的重要作用, 同时也为了评估资源开发所带来的影响, 收集繁殖生物学数据就显得非常重要4, 其繁殖特征及策略可为资源管理提供基础数据。       

南极磷虾种群生物学研究进展III-摄食

鉴于南极磷虾在南极食物网中所处的关键地位,其摄食活动对南大洋海洋生态系统有着极为重要的影响。南极磷虾食物组成因季节、空间等不同而存在差异,且摄食对象的分类和鉴别也存在着较大困难,选食机制目前尚有不同意见。本文从摄食对象、摄食方式、选食机制及摄食率等方面对近百年来南极磷虾摄食生态学研究进行了总结和归纳,以期为国内外学者开展相关研究提供基础信息,并为进一步开展其摄食生态学研究提供科学思路。     

南极磷虾种群生物学研究进展Ⅲ—摄食

鉴于南极磷虾在南极食物网中所处的关键地位,其摄食活动对南大洋海洋生态系统有着极为重要的影响。南极磷虾食物组成因季节、空间等不同而存在差异,且摄食对象的分类和鉴别也存在着较大困难,选食机制目前尚有不同意见。本文从摄食对象、摄食方式、选食机制及摄食率等方面对近百年来南极磷虾摄食生态学研究进行了总结和归纳,以期为国内外学者开展相关研究提供基础信息,并为进一步开展其摄食生态学研究提供科学思路。     

长爪沙鼠的行为和生理生态学研究进展

动物生理生态学主要研究野生动物对自然环境的适应,阐述或回答动物与生存和繁殖相关的生态学问题.长爪沙鼠(Meriones unguiculatus)栖息地环境从西向东横跨荒漠草原和典型草原,而且具有明显的季节性,其生理生态学研究对于了解物种分布范围的决定因素、对季节性环境的适应策略以及种群动态等生态学和进化生物学问题具有重要意义.对本研究组关于长爪沙鼠的生活史特征、能量代谢特征、社群行为和贮食行为、生态免疫以及种群动态等方面的研究进展进行了综述,并对未来可能的发展方向进行展望.     

南极生物圈的基石——南极磷虾

正提到南极的生物,人们首先想到的可能是企鹅、海豹和鲸类,其实还有另一类非常有代表性的生物,那就是这些大型动物的饵料—南极磷虾。无论从哪个角度来衡量,南极磷虾都是我们这颗星球上数量最大和繁衍最成功的动物。在南极食物网中,仅南极大磷虾一个种就足以维持以它为饵料的鲸类、海豹和企鹅的生存与繁衍,所     

中国哺乳动物生理生态学研究进展与展望

中国哺乳动物生理生态学研究自20世纪50年代始,经过70多年的发展,已系统研究了分布于青藏高原、内蒙古草原、横断山脉等地理分布区的代表性物种的生理适应性,研究主题包括能量代谢和体温调节、冬眠（蛰眠）、水代谢、生态免疫、肠道菌群与宿主的能量代谢和产热调节,研究物种以小型哺乳动物为主。在新时期除了进一步加强对极端环境的生理适应研究外,也需关注大型动物对环境的生理适应,发展新兴领域如保护生理学等,同时要借助多组学技术、同位素技术、遥感技术、红外技术等,加强对动物生理适应的机理性探究。本文回顾了中国哺乳动物生理生态学的发展历程,总结了主要领域取得的重要进展。     

南极磷虾种群生物学研究进展Ⅰ-年龄、生长与死亡

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南极磷虾蛋白质提取条件优化

南极磷虾是地球上多细胞生物中生物量最大的单种生物资源之一。南极磷虾因其巨大的生物资源量及潜在的应用价值而受到广泛关注。本文以冷冻南极磷虾为原料,优化了南极磷虾蛋白质的提取条件。在单因素实验的基础上,通过响应面优化实验研究了离心时间、料液比、匀浆时间等对南极磷虾蛋白质得率的影响。结果表明,南极磷虾蛋白质较佳的提取条件为:碱溶阶段p H 11.5,酸沉阶段p H 5.5,离心温度4℃,离心转速10000 rpm,离心时间10 min,料液比1∶3(w/v),匀浆时间3.0 min;在以上提取条件下的南极磷虾蛋白质得率为10.81%。     

昆虫捕食行为生态学研究进展

行为学和生态学是生命科学中正在蓬勃发展的两个分支学科,而行为生态学则是这两个年轻学科的交叉领域。它主要研究生态学中的行为机制和动物行为的存活值、适合度与进化意义[1]从理论上来讲,开展行为生态学的研究,意味着把生态学、行为学、遗传学、生理学和进化论综合起来,并运用了数学和经济学分析方法,所以很有可能在新理论、新概念和新方法的探索上取得突破性进展,也有可能引起生态学的巨大变革;从应用的角度讲,因为动物之所以能极好地适应它们的环境,主要是依靠先天的本能行为适应和后天的学习行为适应,所以深刻地了解动物行…     

Antarctic krill (Euphausia superba Dana) eat salps

 Feeding behaviour of Antarctic krill (Euphausia superba) on salps was observed in shipboard experiments during the 1994/1995 Kaiyo Maru Antarctic Ocean research cruise. The feeding rate was more than 0.5 salp/krill per day. When offered ethanol extracts of four prey types, salps, phytoplankton, krill and polychaetes, krill preferred the salp extracts. This evidence implies that the substances extracted from salps were most attractive to krill. These results might indicate a tight ecological relationship between krill and salps. Received: 24 May 1995/Accepted: 8 October 1995     

Characterization of proteinases from Antarctic krill (Euphausia superba)

Fractions of three trypsin-like proteinases, TL I, TL II, and TL III, a chymotrypsin-like proteinase, CL, two carboxypeptidase A enzymes, CPA I and CPA II and two carboxypeptidase B enzymes, CPB I and CPB II, from Antarctic krill (Euphausia superba) have been characterized with respect to purity by the means of capillary electrophoresis, CE, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The masses of the trypsin-like and chymotrypsin-like proteinases were determined to be 25,020, 25,070, 25,060, and 26,260Da for TL I, TL II, TL III, and CL, respectively. The masses of the CPA enzymes are likely 23,170 and 23,260Da, whereas the CPB enzyme masses likely are 33,730 and 33,900Da. The degradation efficiency and cleavage pattern of the trypsin-like proteinases were studied with native myoglobin as a model substrate using CE, MALDI-TOF-MS, and nanoelectrospray mass spectrometry (nESI-MS). The degradation efficiency of the trypsin-like proteinases was found to be approximately 12 and 60 times higher compared to bovine trypsin at 37 degrees C and 1-3 degrees C, respectively. All three fractions of trypsin-like proteinases showed a carboxypeptidase activity in combination with their trypsin activity.     

Susceptibility of Antarctic krill (Euphausia superba Dana) to ultraviolet radiation

We irradiated captive juvenile Euphausia superba in the laboratory with lower than spring surface levels of ultraviolet-B, ultraviolet-A and photosynthetically active radiation, in order to examine their response in terms of mortality and generalised activity. Levels of photosynthetically active radiation 3–5 times below surface irradiance caused krill to die within a week, while animals in the dark survived. Addition of ultraviolet-B typical of depths up to 15 m were found to significantly accelerate mortality and lead to a drop in activity in all experiments. A drop in activity in krill exposed to ultraviolet-A wavelengths was evident without an increase in mortality. The protein content of animals from various treatments was found not to vary. Accepted: 10 January 1999     

Identification and quantification of prostaglandins in Antarctic krill (Euphausia superba Dana)

Summary The amount and types of prostaglandins present in Antarctic krill (Euphausia superba Dana.) were estimated. Samples of fresh krill were collected during III Antarctic Cruise of RV Polarstern in November 1984. Prostaglandins were extracted, separated by column and thin-layer chromatography and identified as PGA₂, PGB₂, PGE₂, PGF₂. Quantitative measurements were made by a biological method (Vane cascade), concentrations of the most abundant prostaglandins PGE₂ and PGF₂ being 1.6 and 4 ng/1 g of fresh tissue, respectively. Such low level of prostaglandin would not be harmful when using krill as a food supplement.     

Trace element concentrations in Antarctic krill,Euphausia superba

Whole Antarctic krill, Euphausia superba collected along the Western Antarctic Peninsula, were analyzed for 14 elements. Average element abundances (in parentheses) in g/g, in descending order, were as follows: P(9940), Cu (80.5), Zn (43.5), Fe (28.0), Se (5.80), Ba (3.78), Mn (1.98), As (1.92), Ag (1.71), Ni (0.54), Cr (0.30), Cd (0.29), Pb (0.22), and Hg (0.025). Inverse relationships were found between krill length and Hg concentration as well as between As and P levels. A geographic trend of increasing Mn and P levels from southwest to northeast along the Antarctic Peninsula was Sound. Results were compared to earlier data for evidence of metal concentration changes due to anthropogenic activity over the last 15 years.     

Purification and characterization of a proteinase from Euphausia superba Dana (Antarctic krill)

The thiol-dependent serine proteinase (inhibited by DFP, PMSF, pCMB and iodoacetate) was isolated from the whole krill specimens and from the content of the krill digestive tract. The enzyme was purified to homogeneity using a seven-step procedure. Its specific activity with denatured haemoglobin as a substrate was about 6.0 unit/mg. The molecular weight of the enzyme, as determined by gel exclusion chromatography was 33 000 and by polyacrylamide gel electrophoresis with SDS 31 600 (12.5% gel) and 27 000 (7.5% gel). The enzyme is an acidic glycoprotein (pI below 2.9) containing about 5% of carbohydrate. The pH optimum of the enzyme with haemoglobin was 6.0 at the optimal temperature of 40 degrees C in 15-min reaction. The enzyme showed the esterase activity (hydrolysis of BAEE) and was inactive with carbobenzoxy- and benzoyl-dipeptides with the following C-terminal amino acids: Phe, Tyr, Lys, Gly and Leu.     

Collagenolytic serine proteinase from Euphausia superba Dana (Antarctic krill).

1. A serine proteinase isolated from E. superba shows collagenolytic properties: it acts on collagens from Achilles tendon (type I and V) and reconstituted fibrils of calf skin collagen under conditions that do not denature the substrates. 2. At 25 degrees C and pH 7.5 the enzyme both splits the calf skin collagen in solution to the fragments TCA and TCB and catalyses the conversion of dimeric molecules to monomeric chains. 3. The enzyme exhibits strong chymotrypsin-like and lower trypsin-like activities. 4. All the enzyme activities are inhibited to the same degree by diisopropylfluorophosphate (DFP), phenylmethylsulphonyl fluoride (PMSF), N alpha-tosyl-L-lysine chloromethyl ketone (TLCK), soybean trypsin inhibitor (SBTI), chicken ovomucoid (CHOM), chymostatin and leupeptin. None of the activities is inhibited by chelating agents and L-cysteine. 5. pH-Optima of the proteinase in protein substrates hydrolysis (6.0-6.2) are lower than those of synthetic substrates cleavage (7.8-8.0 in the case of BzTyrOEt and 8.7-8.9 for BzArgOEt). 6. Four from nine cysteine residues present in the enzyme molecule possess free thiol-groups. Since the enzyme is inhibited by p-chloromercuribenzoate (pCMB), N-ethylmaleimide (NEM) and iodoacetic acid (IAA), the role of its thiol-groups has been discussed.     

Purification and Characterization of Cold Adapted Trypsins from Antarctic krill (Euphausia superba)

Three trypsins (TRY-ES) were purified from Antarctic krill (Euphausia superba) by ammonium sulfate precipitation, ion-exchange and gel-filtration chromatography, with relative molecular mass of 28.7, 28.8 and 29.2 kDa respectively. The TRY-ES was inhibited by specific trypsin inhibitors (benzamidine, STI, CHOM and TLCK), with optimum temperature at 40 (Trypsin I), 45 (Trypsin II) and 40 °C (Trypsin III) repetitively. The TRY-ES was stabled between 5 and 40 °C, which was consistent with the red shift in fluorescence intensity peak at 40 °C (Trypsin I) and 45 °C (Trypsin II and Trypsin III) and blue shift at 40 °C (Trypsin II and Trypsin III). The K _cat/K _m values of the TRY-ES was 14.28, 9.46 and 5.93 mM^?1s^?1 respectively, 1.1–10.2 folds higher than trypsins from other crustacean and mammal, which was supported by the differences in thermodynamics parameters, the free energy, enthalpy, and entropy of benzamidine and the TRY-ES system.     

Modelling individual growth of the Antarctic krill Euphausia superba Dana

Summary Growth of the Antarctic krill, Euphausia superba, is not easily determined from net catches nor from laboratory experiments. Therefore, in support of these methods, a phenomenological model was constructed which in its present state describes the growth of a single krill specimen under periodically limiting food conditions with summer seasons of variable lengths. Published data of krill body length vs. age and of the annual cycle of primary production of algae in the Drake Passage were used to formulate equations and to calculate growth curves. At 1,000 days after hatching, the model predicts a body length of 63 mm, growth being delayed by 380 days compared with constant, optimal feeding conditions. Final length, weight and time delay are related to the amount of food supplied and compared with published population growth curves.