胭脂鱼鳞片表面结构的扫描电镜观察

鳞片的数目和形态特征常作为鱼类分类的特征之一,也是年龄鉴定和生长状态分析的重要材料。对鱼类鳞片形态特征的研究早就受到广泛注意并在继续深入进行。自七十年代将扫描电镜技术应用于观察鳞片表面结构特征以来,已对近三十种鱼类的鳞片进行了扫描电镜观察研究,其中包括我国的淡水鱼类鲤亚科的几个种。上述研究结果显示出鳞片表面结构的亚显微特征在探讨鱼类系统发育和区别疑难种类上具有一定意义。为丰富我国鱼类鳞片表面亚显微结构资料和满足教学需要,我们对长江中的胭脂鱼Myxocyprinus asiaticus Bleeker 鳞片进行了扫描电镜观察。     

彼得森黄群藻孢囊的形成及形态

利用光镜及扫描电镜对彼得森黄群藻的形态结构、孢囊形成进行详细观察和描述.结果显示,彼得森黄群藻分布广泛,营养体形态变化也大,可以分为不同的变种和变型,其孢囊形态也有多种形态.根据鳞片结构,鉴定出其中的2个变型,并对其所产生的孢囊形态进行了对应.     

厚颌鲂年龄材料的比较

对长江上游特有鱼类厚颌鲂的鳞片和骨组织中的耳石、鳃盖骨、匙骨、基枕骨五种材料的形态结构及年轮特征进行了研究,对用不同材料鉴定年龄的优缺点和鉴定结果进行了比较,认为鳞片、耳石和基枕骨是鉴定厚颌鲂年龄的较理想材料,用鳞片和基枕骨鉴定年龄结果的相符率为95．5％;鳞径和骨径均与体长呈线性关系,并以鳞片和基枕骨为材料进行了生长退算,以骨径进行生长退算更接近于实测值,能更好地反映实际情况。     

一种半咸水害藻—小三毛金藻在我国的出现和防治,

1963年7月初,在大连南关岭几个新挖鱼池放入的十万鱼种,十天内全部死亡。我们起初怀疑是水的盐度较高引起的,作了多次水化学分析和鱼类的试水试验,均未得结论,以后得到中国科学院水生生物研究所的启发,转而从生物学方面着手,终于查明了鱼死亡的原因是一种鞭毛藻类——小三毛金藻(Prymnesiumparvum Carter)的大量繁殖所引起的。1972年7月又蔓延到某些养鱼池,引起鱼类的大量死亡。     

小三毛金藻对盐碱土池塘毒害鱼类的防治研究

小三毛金藻（PrymnesiumparvumCarter）是一种有害藻类。通过以硫酸盐为主的盐碱土池塘的对照试验,总结出采用不同药物、黄泥土、酸性化肥和追施有机肥、提高池塘肥力、促使其它藻类大量繁殖;同时不定期进行水质分析、加注新水、降低盐度、调节pH值等防治措施,使小三毛金藻得到有效的控制。其防治效率达95％以上。自1985年在陕西省大荔、合阳引用这种防治技术到1997年使万亩盐碱地池塘养鱼水面未受到小三毛金藻大的危害。     

杞麓湖鲤鱼鳞片表面结构的扫描电镜观察

采用扫描电镜技术对鲤科鱼类鳞片表面结构进行观察研究,目前国内尚未见报道。本工作主要以杞麓湖的鲤鱼为研究对象,同时观察了鲤亚科其他属鱼类的鳞片表面结构,发现鳞纹上的齿状粒突可能是从无到有,同时探察此结构有无可能作为分类的一项指标。鉴于杞麓鲤的鳞纹上具齿状粒突,而华南鲤则无,再综合考虑二者骨骼性状的差异,作者认为,这些性状可作为将杞麓鲤由普通鲤的一个亚种提升为一个独立种级地位的证据。从鳞片辐射沟的亚显微结构推测,辐射沟具有两方面的功能,一方面可对鳞片的热胀冷缩起缓冲作用:另一方面可增强鳞片的柔软弯曲性。     

白鲢的鳞长与体重及外部形态性状的关系

为了全面地了解鱼类鳞片在鱼类生长及鱼类学的研究中的作用,本文研究了白鲢的鳞片生长与体重及形态可量性状生长的关系。结果表明:白鲢的鳞长与体重、鳞长与24个形态可量性状都呈显著的相关关系,可以从鳞片材料上反映出白鲢体型的基本特征和生长情况。在每尾鱼体上,只要测得体长、全长及鳞长便可预测此尾鱼其它可量性状及体重的数值。这将给鱼类数量分类学及鱼体生长的研究提供简捷方便的途径。 本文还讨论了白鲢的长度与体重关系的表达式,建议应根据具体情况,对鱼体长度指标——全长与体长进行选用。     

革鲀科鳞片构造的扫描电镜观察和比较研究

革鲀科的鳞片构造不同于一般真骨鱼类的骨鳞,由特化的基板和鳞棘两部分组成。中国有革鲀科鱼类12属19种,本文研究了其中10属14种的鳞片构造,运用扫描电镜进行了观察和比较。根据基板表面棱突的特征,可将革鲀科基板构造分为3个式型、2个亚型;根据鳞棘数目、形状及排列方式的不同,可以划分为4个式型。革鲀科各种间的鳞片具有不同的性状,而且比较稳定,因此可以作为分类鉴定的依据之一。     

有害甲藻孢囊的分类鉴定研究进展

有害甲藻孢囊主要是指能产生毒素和(或)能引起有害藻华发生并对水生态系统产生各种危害效应的甲藻孢囊。我国沿海共记录了10属18种,占全球有害甲藻孢囊的3/4。这些有害甲藻孢囊广泛分布于我国沿海,会对水产养殖业造成严重的经济损失,甚至会威胁人类的身体健康。因此,有害甲藻孢囊的多样性及分布越来越受到人们的关注。对有害甲藻孢囊的准确判断不仅对研究其多样性及分布至关重要,而且有助于水产品的安全检验和有害藻华的早期预警。对有害甲藻孢囊的分类主要存在鉴定困难、鉴定不准确等问题。本文综述了有害甲藻孢囊的危害、中国沿海有害甲藻孢囊的种类和分布,以及有害甲藻孢囊的鉴定等3个方面的研究进展,并提出利用孢囊及营养细胞的形态学特征、分子生物学、毒理学等多学科研究手段准确鉴定有害甲藻孢囊的建议。     

鱼鳍和鳞片色素组成的比较观察

鱼类体色观察常以鳞片为材料,鱼鳍和鳞片都是皮肤的衍生物,采用Nikon光学显微镜系统,对白鲫和红鲫鱼鳍及相邻体位鳞片的色素细胞组成、分布及形态结构等进行了比较观察。鱼鳍薄而透明,显微镜下观察发现鱼鳍从近体端到远体端在色素细胞总体分布上呈现出由密集逐渐稀疏的变化特征。白鲫背、胸、腹、臀、尾鳍五种鱼鳍中都分布有黑色素细胞、黄色素细胞和红色素细胞三种色素细胞类型。红鲫鱼鳍中则仅观察到黄色素细胞和红色素细胞两种色素细胞类型。同时不同部位鱼鳍与其基部相邻鱼鳞上层在色素细胞的组成上是一致的。在白鲫和红鲫的鳞片中均存在着丰富的虹彩细胞,但在鱼鳍中未观察到典型的虹彩细胞的分布,提示在鱼类体色发育中,虹彩母细胞可能具有与其它几种色素母细胞不同的迁移途径。     

Kurze Mitteilung: Fischsterben durch Prymnesium saltans Massart im Kleinen Jasmunder Bodden (Rügen) im April 1990

Mass mortality caused by Prymnesium saltans Massart in the Kleiner Jasmunder Bodden (Rügen), April 1990 A report on the reasons, spread and extent of a mass mortality in a Bodden water near the Isle of Rügen (Germany). The cause of mass fish mortality was an abundance of the toxic algae Prymnesium saltans Massart, with approx. 300000000 cells per liter.     

Toxin-assisted micropredation: experimental evidence shows that contact micropredation rather than exotoxicity is the role of Prymnesium toxins

Blooms of Prymnesium parvum can severely harm fish and zooplankton, presumably through the release of allelopathic exotoxins that offer advantages for Prymnesium in its interactions with competitors and prey. We show that Prymnesium attaches to zooplankton and fish, causing mortality, whereas exposure of these organisms to Prymnesium across a permeable membrane does not cause mortality. We also show that Prymnesium exotoxins are released independently of contact toxicity only in response to experimental procedures or natural causes of stress. Our results are consistent with the idea that toxins have evolved for release during cell-to-cell contact in support of heterotrophy. The evolution of toxin-assisted micropredation would be consistent with mechanisms of natural selection favouring individual fitness as opposed to broadcast allelopathy from which the benefits are more dispersed. Research into the toxicity of Prymnesium and other harmful algal species may profit from focus on processes following physical contact with potential prey.     

Aspects of the ecology of Prymnesium parvum (Haptophyta) and water chemistry in the Norfolk Broads, England

SUMMARY. Prymnesium parvum , an ichthyotoxic phytoplankter, has been recorded, at times abundantly, in the River Thurne, Norfolk, and its associated Broads. Its occurrence has been apparently more frequent and its population sizes probably larger since the late 1960s than previously and fish mortalities due to it now occur almost annually.
The Thurne system is brackish and may have become more so, due to exploitation by drainage pumps, of a saline water table, in recent years. Evidence for this is conflicting, but in any case an increase in salinity is unlikely to have made increased Prymnesium growth more likely. Eutrophication of some Broads in the system is most likely to have increased the populations of Prymnesium since the late 1960s and data are presented on the present water chemistry of the system for comparison with previous records, and on current phytoplankton and Prymnesium crops in different parts of it.
P. parvum has been isolated from the system as a unialgal culture and compared in morphology, salinity tolerance and ichthyotoxicity with a strain of P. parvum from Israel. The Broads strain differs slightly in size and pigmentation, but not in salinity tolerance. In culture it produces more ichthyotoxin than the Israeli strain.     

Microscopic eukaryotes living in a dying lake (Lake Koronia, Greece)

The morphological and phylogenetic diversity of the microscopic eukaryotes of the Lake Koronia water column was investigated during a mass kill of birds and fish in August–September 2004. The dominant morphospecies corresponded to the known toxin-producing species Prymnesium parvum , followed by Amoebidium sp., a taxon belonging to the group of parasitic Mesomycetozoea , and the common chlorophyte Pediastrum boryanum. Prymnesium exhibited heteromorphic life-cycle stages (flagellate and nonmotile coccoid cells). Phylogenetic analysis with 18S rRNA gene suggested that these heteromorphic stages belonged to the Platychrysis – Prymnesium monophyletic group. The most abundant phylotype was almost identical to P. boryanum . The fungal phylotypes were related to the Chytridiomycota , and the ciliate-like ones were closely related to Enchelys polynucleata and Pattersoniella vitiphila . Two phylotypes representing novel members belonging to the Jakobida and the Apicomplexa were also found. The microscopic eukaryotes of Lake Koronia include several organisms that are related to parasitic life modes.     

Automated detection and enumeration for toxic algae by solid-phase cytometry and the introduction of a new probe for Prymnesium parvum (Haptophyta: Prymnesiophyceae)

Harmful algal blooms have a severe impact on aquaculture andfishery and can be caused by toxic haptophytes and dinoflagellates.Different toxic species, which are not easy to distinguish fromtheir morphologically similar and non-toxic relatives, occurin both groups. Sequencing of the large subunit ribosomal RNAof different strains and taxonomic relatives allowed the designof a probe specific to the toxic Prymnesium parvum spp. Forthe rapid detection and enumeration of Prymnesium and Alexandriumcells in cultures and environmental samples, respectively, protocolsfor fluorescence in situ hybridization were adapted for automateddetection by a solid-phase cytometer, the ChemScan. This cytometerenables the automated counting of fluorescently labelled cellson a membrane filter and subsequently a microscopic verificationof these results by the user, because the motorized stage ofthe microscope is driven to each positive signal by the computersoftware to localize that cell on the filter. With this fastdetection method, it was possible to detect, enumerate and verifymicroalgal cells on a filter, with a detection limit of onecell per membrane filter.     

Rapid quantification of the toxic alga Prymnesium parvum in natural samples by use of a specific monoclonal antibody and solid-phase cytometry

The increasing incidence of harmful algal blooms around the world and their associated health and economic effects require the development of methods to rapidly and accurately detect and enumerate the target species. Here we describe use of a solid-phase cytometer to detect and enumerate the toxic alga Prymnesium parvum in natural samples, using a specific monoclonal antibody and indirect immunofluorescence. The immunoglobulin G antibody 16E4 exhibited narrow specificity in that it recognized several P. parvum strains and a Prymnesium nemamethecum strain but it did not cross-react with P. parvum strains from Scandinavia or any other algal strains, including species of the closely related genus Chrysochromulina. Prymnesium sp. cells labeled with 16E4 were readily detected by the solid-phase cytometer because of the large fluorescence signal and the signal/noise ratio. Immunofluorescence detection and enumeration of cultured P. parvum cells preserved with different fixatives showed that the highest cell counts were obtained when cells were fixed with either glutaraldehyde or formaldehyde plus the cell protectant Pluronic F-68, whereas the use of formaldehyde alone resulted in significantly lower counts. Immunofluorescence labeling and analysis with the solid-phase cytometer of fixed natural samples from a bloom of P. parvum occurring in Lake Colorado in Texas gave cell counts that were close to those obtained by the traditional method of counting using light microscopy. These results show that a solid-phase cytometer can be used to rapidly enumerate natural P. parvum cells and that it could be used to detect other toxic algae, with an appropriate antibody or DNA probe.     

Fish kills related toPrymnesium parvum N. Carter (Haptophyta) in the People's Republic of China

Prymnesium parvum has been known to cause mass mortality of fish in PR of China since 1963. It usually occurs in brackish waters and inland high-mineral waters. The fish-breeding industry (mainly species of carp) in these regions of the PRC has been threatened by this microalga. Electron microscopic examination of isolates from Dalian and Tianjin revealed that the isolates wereP. parvum, based on specific scale patterns and two kinds of scales. The symptoms of the poisoned fish and the control of this toxic alga are also discussed. The addition of ammonium sulfate, copper sulfate, mud, reduced salinity and organic fertilizer to fish ponds has been partially successful in controlling blooms of this toxic alga. Adding 50–70 kg ha^–1 day^–1 manure (dry weight) to the fish pond to inhibitP. parvum from becoming the dominant species in the fish pond is recommended. A reduction in salinity to less than 2 is the easiest way to save freshwater fish from being poisoned byP. parvum. Use of ammonium sulfate is an efficient, economical and safer method to controlP. parvum than copper sulfate or mud.     

Specificity of Glycerol for Dark Growth of Prymnesium parvum

SYNOPSIS. Out of 64 nutrients tested, none replaced glycerol for growth in the dark of Prymnesium parvum. Some metabolites enahanced growth in the light, and in the presence of glycerol also in the clark. Good growth with glycerol could be obtained in the absence of CO₂. Survival of cultures in the dark in media without glycerol was prolonged by various nutrients. Thioglycerol in glycerol-containing media inhibited growth in light and darkness. Apparently Prymnesium parvum has a specific glycerol requirement for dark growth.     

ULTRASTRUCTURE OF PRYMNESIUM NEMAMETHECUM SP. NOV. (PRYMNESIOPHYCEAE)1

Based on material collected from Cape Town, a new sand-dwelling, marine species of Prymnesium is described. Using light and electron microscopy, Prymnesium nemamethecum sp. nov. has been found to resemble other species of the genus in size, organelle arrangement, and swimming behavior. It differs from other described species in that it has three types of scales, one of which is confined to the region of appendage insertion and forms a sheath of simple plate scales over the haptonema. In addition, the scales constituting the proximal body scale layer(s) are unusual because they are not simple plate scales but are specifically ornamented.