In vitro culture of embryonic hearts from guppy fish (Poecilia reticulata)

Forty embryonic hearts were taken out by anatomical needle from denuded embryos of the ovoviviparity guppy fish that were dechorioned by mechanic method or by trypsin digestion, and were in vitro cultured. In the cultured hearts, 80% have maintained beating in vitro for 4 weeks, and the longest record for beating was 142 d. Owing to fish embryo transparency, beating frequency and blood color changes are easily viewed from the embryonic hearts under a dissecting microscope. The current study established the in vitro culture method of embryonic hearts in guppy fish, which can be used as a model for the study of heart and cardiovascular system in vertebrates.

Development of a rapid, sensitive and specific diagnostic assay for fish Aquareovirus based on RT-PCR

A rapid, sensitive and highly specific detection method for Aquareovirus based on reverse-transcription polymerase chain reaction (RT-PCR) was developed. Based on multiple sequence alignment of the cloned sequences of a local isolates, the Threadfin reovirus (TFV) and Guppy reovirus (GPV) with Grass carp reovirus (GCRV), a pair of degenerate primers was selected carefully and synthesized. Using this primer combination, only one specific product, approximately 450 bp in length was obtained when RT-PCR was carried out using the genomic double-stranded RNA (dsRNA) of TFV, GPV and GCRV. Similar results were also obtained when Chum salmon reovirus (CSRV) and Striped bass reovirus (SBRV) dsRNA were used as templates. No products were observed when nucleic acids other than the dsRNA of the aquareoviruses described above were used as RT-PCR templates. This technique could detect not only TFV but also GPV and GCRV in low titer virus-infected cell cultured cells. Furthermore, this method has also been shown to be able to diagnose GPV-infected guppy (Poecilia reticulata) that exhibit clinical symptoms as well as GPV-carrier guppy. Collectively, these results showed that the RT-PCR amplification method using specific degenerate primers described below is very useful for rapid and accurate detection of a variety of aquareovirus strains isolated from different host species and origin. (C) 2004 Elsevier B.V. All rights reserved.

丁香属（Syringa L.）的分类学修订

丁香属隶属于木犀科，分布于东南欧和东亚至喜马拉雅地区，我国是丁香属的现代分布中心。《中国植物志》（61卷，1992）记录了我国野生丁香种类16种;《Flora of China》（15卷，1996）记录了中国原产丁香种类16种，并认为全世界大约有20种。丁香属属下分类等级划分分歧较大，很多种的划分也存在争议。花叶丁香、四川丁香等种类是根据栽培植物描述的，没有指定模式标本，给分类处理带来了一定困难。另外，丁香属很多分类群的性状变异非常复杂，仅根据有限的标本很难做出合理的分类处理。本研究通过广泛查阅文献和标本，同时进行野外居群取样和性状观察，对各类群的性状在居群内和居群间的变异进行统计学分析，判断其分类价值，并运用多变量分析的方法，为各类群的合理划分提供依据。结合性状分析和地理分布等证据，做出分类处理。 作者查阅了国内外16个标本馆的近2000份标本，其中模式标本约70份。对我国12个省市的40余个居群进行了取样和观察，采集标本500余份，涉及了《中国植物志》61卷收录的除了藏南丁香以外的所有类群。通过对9个复合体的40余个性状在居群内和居群间的变异进行统计分析，发现叶片类型、叶柄长度、花序着生类型、花冠大小、花丝长度、花药颜色在不同类群间差异明显，可以用作划分种的依据;叶片形状、叶片毛被、花序轴毛被、花冠管形状等性状在有些复合体内的居群间呈现连续的变异，只能用作种下等级（亚种）的划分;叶片大小、花序轴形状、花药着生在花冠的位置、蒴果是否被皮孔等性状在不同复合体的居群间呈现间断或连续的变异，视不同情况可以用作种间或种下等级的划分依据，或作种内变异处理;而叶脉、花色、花萼齿裂、花冠裂片形状等性状在居群间差异不大，不适合用作分类依据。 在性状分析和多变量分析的基础上，本文将丁香属划分为2组2系12种13亚种，其中短花冠管组有1种3亚种;长花冠管组的顶生花序系有5种5亚种，侧生花序系有6种5亚种，并指定了各组和系的模式种;编制了属下各组、系、种和亚种划分的检索表，对12种13亚种进行了形态描述、标本引证，给出了地理分布图和生境，并提出了分类处理依据。文中对巧玲花、皱叶丁香、红丁香和云南丁香等复合体内的一些分类群进行了归并，做出4个新组合：S. pubescens ‘Meyer’、S. villosa subsp. wolfii、S. yunnanensis subsp. sweginzowii和S. yunnanensis subsp. tomentella，处理了11个新异名（S. fauriei H. Lév.、S. julianae C. K. Schneid.、S. meyeri var. spontanea M. C. Chang、S. pinetorum W. W. Sm.、S. wardii W. W. Sm.、S. oblata var. donaldii R. B. Clark et J. L. Fiala、S. afghanica C. K. Schneid.、S. protolaciniata P. S. Green et M. C. Chang、S. tibetica P. Y. Bai、S. reflexa C. K. Schneid. 、S. wilsonii C. K. Schneid.）。作者指定了3种4亚种(S. reticulata subsp. reticulata、 S. reticulata subsp. amurensis、S. pubescens subsp. microphylla、S. oblata subsp. dilatata的后选模式，并对其它10个名称指定了后选模式。文中还提出了分类处理原则，对我国丁 香属的分布及各地方植物志的记载进行了评述，并对丁香属的分布格局提出了作者的看法。 作者还对13个分类群的16号材料进行了染色体观察，发现除了毛丁香有染色体2n=48外，其它均为2n=46，其中朝阳丁香的染色体数目为首次报道。对小叶巧玲花不同异名（包括小叶蓝丁香、小叶巧玲花与小叶蓝丁香的杂交种）的材料进行染色体观察时，发现它们之间差异很小，进一步佐证了作者将其合并的合理性。另外野生的花叶丁香（华丁香）与栽培的花叶丁香在染色体数目上也无差异，支持了作者认为二者为同物异名的观点。

江西彭泽鲫生殖方式的初步研究

<正> 雌核发育是动物界中一种少有的生殖方式。在鱼类中迄今已发现Poecilia formosa,Menidiaclarkhubbsi是行雌核发育的单性鱼类,欧洲的银鲫(Carassius auratus gibelio)。Poeciliopsis属的某些类型亦是行雌核发育的。近10余年来,我国继发现黑龙江省方正县双风水库的银鲫是两

鱼类的人工雌核生殖

<正> 雌核生殖(gynogenesis)是单性生殖(parthenogenesis)的一种,指卵子依靠自己的细胞核直接发育成个体的生殖行为。自然界实行雌核生殖的动物有:蜜蜂、蚂蚁、蚜虫,水蚤、轮虫、丰年虫、银鲫、食蚊鱼(Poecilliopsis)的一些种类(如花鳉Poecilia formosa)等等。

Reevaluation of the phylogenetic relationship between Mobilid and Sessilid peritrichs (Ciliophora, Oligohymenophorea) based on small subunit rRNA genes sequences

Based on morphological characters, peritrich ciliates (Class Olygohymenophorea, Subclass Peritrichia) have been subdivided into the Orders Sessilida and Mobilida. Molecular phylogenetic studies on peritrichs have been restricted to members of the Order Sessilida. In order to shed more light into the evolutionary relationships within peritrichs, the complete small subunit rRNA (SSU rRNA) sequences of four mobilid species, Trichodina nobilis, Trichodina heterodentata, Trichodina reticulata, and Trichodinella myakkae were used to construct phylogenetic trees using maximum parsimony, neighbor joining, and Bayesian analyses. Whatever phylogenetic method used, the peritrichs did not constitute a monophyletic group: mobilid and sessilid species did not cluster together. Similarity in morphology but difference in molecular data led us to suggest that the oral structures of peritrichs are the result of evolutionary convergence. In addition, Trichodina reticulata, a Trichodina species with granules in the center of the adhesive disc, branched separately from its congeners, Trichodina nobilis and Trichodina heterodentata, trichodinids without such granules. This indicates that granules in the adhesive disc might be a phylogenetic character of high importance within the Family Trichodinidae.

Changes in the structure of a zooplankton community during a Ceratium (dinoflagellate) bloom in a eutrophic fishless pond

The community structure of zooplankton was studied in a eutrophic, fishless Japanese pond. The ecosystem was dominated by a dinoflagellate, Ceratium hirundinella, two filter-feeding cladocerans, Daphnia rosea and Ceriodaphnia reticulata, and an invertebrate predator, the dipteran Chaoborus flavicans. The midsummer zooplankton community showed a large change in species composition (the Daphnia population crashed) when a heavy Ceratium bloom occurred. It is shown that (i) the rapid density decline of D.rosea in mid-May was mainly caused by a shortage of edible phytoplankton, which was facilitated by the rapid increase in C.hirundinella abundance; (ii) the low density of D.rosea in June-July was considered to be mainly caused by the blooming of Ceratium hirundinella (which may inhibit the feeding process of D.rosea), while predation by C.flavicans larvae, the changing temperature, the interspecific competition and the scarcity of edible algae were not judged to be important; (iii) the high summer biomass of the planktonic C.flavicans larvae was maintained by the bloom of C.hirundinella, because >90% of the crop contents of C.flavicans larvae were C.hirundinella during this period. The present study indicates that the large-sized cells or colonies of phytoplankton are not only inedible by most cladocerans, but the selective effect of the blooming of these algae can also influence the composition and dominance of the zooplankton community, especially for the filter-feeding Cladocera, in a similar way as the selective predation by planktivorous fish. The large-sized phytoplankton can also be an important alternative food for ominivorous invertebrate predators such as Chaoborus larvae, and thus may affect the interactions between these predators and their zooplanktonic prey. In this way, such phytoplankton may play a very important role in regulating the dynamics of the aquatic food web, and become a driving force in shaping the community structure of zooplankton.

生态恢复后的千烟洲植物群落种类组成及结构特征

Qianyanzhou(QYZ) Ecological Station established in 1983 with an area of 204 hm~2 is affiliated to the Chinese Ecosystem Research Network.Before 1982,herbs had been dominant,sparsely dotted with shrubs.After 20-year restoration of the vegetation,the vegetation showed significant changes in both forest coverage and species diversity.Forest coverage had increased to 93.3% in 1999 from 0.4% in 1982.The vegetation could be broadly classified into two groups: artificial forest,accounting for the most percent,and natural secondary forest.These two groups could be subdivided into 12 types.Based on the 2003 field work,The authors studied plant community composition and vertical structure.The results were as follows: 1) On the study plots were there about 150 species,of which 100,49,and 47 grew in arbor layer and shrub layer and herb layer,respectively.Of 12 community types,the amount of species in shrub layer was larger than that of other two layers.As to the species richness in the different community types,Liquidambar formosana community showed the highest and Imperata cylindrical var.major community the least.The amount of species in arbor layer of artificial forest was smaller than those of natural Pinus massoniana forest,but no difference in understory.2) Loropetalum chinense,Quercus fabric and Vaccinium bracteatum were dominant shrub species with a wide distribution.Three ferns Woodwardia japonica、Dryopteris atrata and Dicrannepteris dichotoma were dominant herb species.Lianas were sparse,but Milletlia reticulata were found in all forest types.3) Up to now some natural regeneration species,such as Eurya muricata、Quercus fabri、Vaccinium bracteatum、Rhus chinensis、Adinandra bockiana,had grown in the arbor layer of artificial forests.Some herb species,such as Arundinella setosa、Miscanthus floridulus、Isachne globosa、Scirpus triqueter,which were dominant ones in the herb layer before the restoration of vegetation,disappeared now.4) The vertical structure of natural Pinus massoniana community and Liquidambar formosana community showed more complex comparing with artificial forests.For the artificial forests,the conifer and broad-leaves mixed forest had a more complex structure.In both natural Pinus(massoniana) community and Liquidambar formosana community,it was dominated by individuals with height of 3～4 m,while 10～12 m in the artificial forests.