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81.
本文用11种酶底物,测定了紫贻贝、日本蟳和滨螺消化系统的酶活性,并初步研究了这些消化酶的应用。实验表明:1.0%的紫贻贝消化酶在25℃,20分钟内可水解去除蟳鱼受精卵膜。1.0%的该消化酶加入等体0.5%的半纤维素酶和果胶酶,在30℃、60分钟内可制备出大量啤酒酵母原生质体。在同样条件下.1.5-2小时内,可去除大部分三角褐指藻的细胞壁。  相似文献   
82.
中国软骨鱼类资源概述及其利用问题的商榷   总被引:1,自引:0,他引:1  
一.引言鱼类可方便地分为软骨鱼类和硬骨鱼类两大类。软骨鱼类包括鲨鱼、鳐鱼与银鲛等鱼类。本文主要叙述中国软骨鱼类的资源概况,特别是它们的种类成分、分布情况、生活习性、质量和数量以及一般捕捞情况;同时也商讨一下它们的利用和增产等问题。为便于读者了解起见,现在先把软骨鱼类简要地介绍如下。1.软骨鱼类的形态特征软骨鱼类的主要特征有以下几点:(1)内骨胳完全由软骨组成,没有真骨;(2)体被盾鳞,或光滑无鳞;(3)鳃裂5—7对,个别开口于体外(银鲛例外,具有一膜状鳃盖和一外鳃孔);(4)雄性的腹鳍里侧具一交接器,或称鳍脚;(5)尾常为歪形;(6)鼻孔腹位;(7)卵大而数少,体内受精。此外,还有许多内部特征,这里从略了。  相似文献   
83.
海洋无脊椎动物缺乏真正意义上的抗体,没有免疫记忆,只能靠非特异性免疫系统防御和抵抗病原体的感染.酚氧化酶原激活系统是海洋无脊椎动物非特异性免疫系统中至关重要的一员,而酚氧化酶作为该系统末端的一种含铜金属酶,则通过催化黑化反应在海洋无脊椎动物非特异性免疫防御中发挥了关键的作用.本文结合作者已有的研究成果并综合本领域的大量参考文献对酚氧化酶原激活系统和酚氧化酶的免疫学功能、激活机制、生化性质与酶性质以及基因与分子结构等方面的研究进展进行综述.  相似文献   
84.
Penguin and skua in the maritime Antarctic have high salt loadings in the body due to almost exclusive diet consumption of marine invertebrates. However, the storage and turnover of sodium and potassium in these animals are poorly investigated. Here we determined the concentration and microscopic distribution of the two elements in the bones of penguin and skua. The average concentrations of sodium and potassium in penguin bone were comparable with that in skua bone (0.18% and 0.82% for penguin bone; 0.19% and 0.76% for skua bone in dry weight). The ratios of sodium to calcium and potassium to calcium (0.0330 and 0.0075 for penguin, 0.0335 and 0.0082 for skua in average by weight) were somewhat higher than the reported ratios for terrestrial animals, indicating these marine animals' bone enrichment of salt. The ratios of sodium to potassium in average by weight were 6.75 and 4.65 for penguin and skua, respectively. This value is much lower compared with the bulk sea water ratio of about 27.0, implying that potassium is favorable to reside in the bone rather than sodium. Both sodium and potassium were found to significant correlation with the content of organic materials in bone based upon the intensity of native signal determined by electron paramagnetic resonance (EPR). It was estimated that almost all of potassium is kept within the organic phases, while about 30% of sodium is stored in organic phases and the other 70% within mineral phase. The microscopic distributions of potassium in the cross-section and/or surface were revealed by synchrotron radiation X-ray fluorescence (SR-XRF) technique. The ratio of potassium to calcium based upon the SR-XRF intensity counter varied considerably from the surface to the interior, and on the surface the highest concentration of potassium was observed in the middle section with decreasing amounts toward the edge. This indirectly documented that exchange of potassium between fluid and bone organic phase maybe occur.  相似文献   
85.
2007-2008年千岛湖营养盐时空分布及其影响因素   总被引:2,自引:2,他引:0  
2007-2008年对千岛湖水体中5个采样点(S1,S3,S4,S8,S9)的总氮、总磷、三态氮、溶解性总磷和可溶性活性磷等进行了不同深度的逐月监测,以研究探讨千岛湖营养盐的时空分布格局.结果表明,两年间总磷、总氮和硝酸盐氮浓度都呈现从上游(S1)至下游(S9)逐渐下降的趋势;2007-2008年汛期(3-7月)位于千岛湖上游新安江干流段的样点S1各种营养盐均为全年最高.但是2007年与2008年营养盐时空分布差异显著.2008年汛期(3-7月),S1的总磷和总氮浓度分别极显著低于和高于2007年同期.相对于2007年,虽然2008年具有更高的温度,但没有增强水体热稳定性.2008年强对流天气一方面通过打破水体热分层和促进水体混合,另一方面通过雨水带来大量的地表营养盐来影响营养盐的分布.汛期高浓度的总磷在1-2个月内平均降低64.4%,最大降低88.6%,显示千岛湖生态系统具有较强的净化能力.分析结果显示千岛湖营养盐时空分布总体格局是由水文、生物以及人类活动等各种因素之间的相互作用所产生的综合效应而形成的,而极端天气能够改变这一格局.  相似文献   
86.
With the decline of fish stocks, the proportions of economically important invertebrates like crustaceans and cephalopods have increased in the Bohai Sea. The community structure and trophic level of economically important invertebrates were analyzed using the bottom trawl survey data collected by the Yellow Sea Fisheries Research Institute in the Bohai Sea in May and August of 1958–1959, 1982, 1992–1993, 2004, 2009 and 2015. A total of 37 species of economically important invertebrates, belonging to 5 orders, 24 families, were captured. The biomass densities of economically important invertebrates in the Bohai Sea displayed an overall downward trend from 1982 to 2015. Oratosquilla oratoria and Loligo spp. were the most dominant species in the past 30 years, the biomass proportion of O. oratoria increased gradually in both May and August from 1982 to 2015. Moreover,biodiversity indices of economically important invertebrates in the Bohai Sea appeared to decline from 1982 to2004 and then increased in 2015. Similarly, the mean trophic level of economically important invertebrates declined from 1982 to 2004 and increased slightly in 2015. Overall, although the proportions of invertebrates have increased, the biomass densities in the Bohai Sea have displayed an overall downward trend from 1982 to 2015.The increases in the biodiversity and trophic level of economically important invertebrates after the 2000 s,possibly benefit from stock enhancement projects implemented by governments at different levels and national fishery management measures such as the "double-control" of the total number and engine power of fishing vessels and summer moratorium of fishing.  相似文献   
87.
朋友,如果你是一个科普爱好者,或是一个善于探秘的人,一定会对各地的自然博物馆和地质博物馆感兴趣,因为博物馆里有许多鲜为人知的秘密。你会看到诸如恐龙、大象等大型动物的化石,也会看到长在石头里的树叶和小鸟……这就是化石。  相似文献   
88.
Mercury (Hg) is one of the commonly encountered heavy metals, which is widespread in inshore sediments of China. In order to investigate the toxicity of Hg on marine invertebrates, we studied the effects of the divalent mercuricion (Hg2+) (at two final concentrations of 0.0025 and 0.0050 mg L−1, prepared with HgCl2) on metallothionein (MT) content, DNA integrity (DNA strand breaks) and catalase (CAT) in the gills and hepatopancreas, antioxidant enzyme activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), in the hemolymph, gills and hepatopancreas of the portunid crab Charybdis japonica for an experiment period up to 15 d. The results indicated that MT was significantly induced after 3 d, with a positive correlation with Hg2+ dose and time in the hepatopancreas and a negative correlation with Hg2+ dose and time in the gills. While CAT in the hemolymph was not detected, it increased in the hepatopancreas during the entire experiment; SOD and GPx in the three tissues were stimulated after 12 h, both attained peak value and then reduced during the experimental period. Meanwhile, DNA strand breaks were all induced significantly after 12 h. These results suggested the detoxification strategies against Hg2+ in three tissues of C. japonica.  相似文献   
89.
To obtain information on food web structure in salt marshes of the Changjiang (Yangtze) River Estuary, the δ13C and δ15N values of primary producers and consumers were determined. The mean δ13C values of 31 dominant consumers ranged from -23.13‰ to -14.37‰. Except for several species (Eriocheir sinensis, Sinonovacula constricta and Potamocorbula ustulata), consumers had intermediate δ13C values between those of benthic microalgae and Spartina alterniflora. The mean δ15N values of 31 dominant consumers varie...  相似文献   
90.
许多海洋无脊椎动物在变成附着成体之前,有一个浮游幼体阶段。幼体的浮游生活短则几分钟。长达数月。一般来说,海洋无脊椎动物幼体的附着变态主要由外界环境因子和内源性因子控制,特别是外界环境因子对许多海洋无脊椎动物的幼体附着和变态起着极为重要的作用。  相似文献   
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