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1999年  第20卷  第6期

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研究论文
Radioimmunoassay,enzyme-linked immunospot assay and enzyme immunoassay were used for the determinations of plasma steroid hormones level,antibodyproducing cells counting and IgM level in this study.The decreased number of antibody producing cells and low IgM levels were observed in sexual immature rainbow trout during the spawning season.These fish were reared under almost constant water temperature and natural photoperiod.Moreover,low IgM level was also observed in immature rainbow trout,which were reared under short photoperiod,and IgM level was not changed by treatment of testosterone.The results suggest that photoperoid may cause the changes in immune competence.It is possible that circadian rhythm accompanied with photoperiod may influence physiological function of fish,so that immune competence is changed.
An electron microscopic study of resting cysts and their organelles in Paraurostyla weissei has revealed that:1)The cyst wall is composed of four layers named from outside to inside:ectocyst,mesocyst,endocyst,and granular layer.The granular layer is delimited by the cell pellicle.Both the layer and pellicle contain a few vesicles.2)Tubular mitochondria are apparent contrast to their surrounding cytoplasm.The mitochondria are mostly converged to each other,except that a few of those separately scattered in cytoplasm.3)There are a lot of autophagic vacuoles which contain digested,undigested mitochondria and other organelles,and,these vacuoles undergo digestivelly cyclic changes.4)The well developed endomembrane system are widely dispersed over cytoplasmic area.It is supposed from these observations that:(1)The above vesicle are the structure of resting cell,which would be used in exchange for the matter between the granular layer and cytoplasm on both sides of the pellicle.(2)The digestion within autophagic vacuoles might be the main way to supply material and energy in the resting cell.And,as an important source,the membranous structures,which exist in the cytoplasm,would be used to form the membrane of autophagic vacuoles.
Neuron and glial cells of ganglion in the crab Eriocheir sinensis were studied by using optical and transmission electron microscope.Each ganglion consists of many neuron and glial cells.According to the size and shape of cell,nuclei and the distribution of chromatin,the glial cells can be distinguished into three types:astrocyte,oligodendrocyte and microglial cell.The cell membrane appears three-layered,and the cytoplasm inclusions of neuron consist of Nissl body,Golgi body,endoplasmic reticulum and mitochondrium.There are many organelles in glial cytoplasm which are similar to those in neuren cell.Astrocyte nucleus is the largest and is ellipse;oligodendrocyte nucleus is spherical;microgolal nucleus is triangle or ellipse and is the smallest one.There is relationship between the quantity of neuron cells and the ability of physiological activity of appendix,that is,the more neuron cells,the stronger the ability of appendix.
The classification of some Chinese species of Agkistrodon and Deinagkistrodon remains controversial.As to now,the works mainly dealt with external morphological feathers and little involved internal characters.In this paper,a comparative study on skull morphology of 8 Chinese species (including subspecies) of Agkistrodon and Deinagkistrodon from 13 populations is performed,and the status and validity of some species are discussed.The results reveal:1) brevicaudus is different from its congener blomhoffii in the following characters:the squamosal of blomhoffii doesnt extend beyond the posterior end of the braincase and pterygoid teeth extend beyond the junction with the ectopterygoid.So it supports the suggestion made by Zhao (1998) that brevicaudus,which was treated as a subspecies of blomhoffii by many workers,should be placed at a species status and designated A.brevicaudus.2) ussurisensis is separable from blomhoffii by the presence of weak parietal shield,broad and short lateral process of the fork of the ectopterygoid,pterygoid teeth not extending beyond the junction with ectopterygoid,squamosal extending beyond the posterior end of the braincase;from halys by the presence of postfrontal touches frontal,dorsal scale rows at midbody 21.These characters strengthen the idea that ussuriensis is a full species.3) saxatilis differs from intermedius in several characters,skull proportion of length to width,shape of parietal,the parietal shied and so on,so it is confirmed that saxatilis,which was treated as a subspecies of intermedius by Gloyd et al.(1990),is a full species.4) shedaoensis is distinct from its congener saxatilis in characters of shape of squamosal,basisphenoid and basioccipital process,postfrontal;it is a valid species.5) A.halys qinlingensis Song can be separable from the relative species such as strauchii,halys and intermedius in the following characters:the shape of parietal,pterygoid teeth dont extend beyond the junction with ectopterygoid,squamosal extends beyond the posterior end of the braincase,parietal shield and dorsal scale rows at midbody.Thus raising A.h.qinlingensis as a full species is supported.Comparison studies on skulls among genera Agkistrodon and Deinagkistrodon are also completed.In the end of the paper,the key to these 8 species based on the skull characters was provided.
Population estimates of black-crested gibbons in Wuliang Nature Reserve,Jingdong,Yunnan,China,with two techniques,average group density-total area and average home rang-forest coverage,produced quite similar results.The population was estimated around 115 groups in the Reserve.The paper also discussed the conservation problems of the Reserve.At present,the main threat to the gibbons is habitat fragmentation and population isolation.Thus,it is urgent to prohibit hunting and protect the habitat and forest corridors or habitat bridges.
A parameter,index of aggregation (A),was coined in order to quantify the degree of aggregation of biological populations.This index was used to analyze the relationship between aggregation and population dynamics of Dactylogyrus vaginulatus Zhang et Niu,1966 on Hypophthalmichthys molitrix,in company with variance to mean ratio and the parameter k in negative binomial distribution.Result indicated the degree of aggregation of D.vaginulatus in host population decreased as the prevalence and the abundance increased.As a measurement,the parameter A proves to be more reliable than k,and k better than variance to mean ratio.Analyses also pointed that the power (b) in Taylors equation,which has been used widely to study the spatial pattern of population distributions,is not constant,and the death of hosts caused by parasites may be responsible for its fluctuation.The successful use of Taylors equation in biological population may come from the demographic stochasticity.
Gansu zokor (Myospalax cansus) is a solitary fossorial rodent inhabiting in its own tunnel system all its life.In this paper,the sex ratio in wild population of Gansu zokor,the variation of sex ratio among seasons,years and age groups,and the relationship between the sex ratio and the environment factors were studied.The result showed:1) the sex ratio in wild population of Gansu zokor was 1.57 (♀/♂) (χ[2]=47.6,P<0.01);2) sex ratio changed among seasons and age groups;3) sex ratio also changed among years,but not significantly;4) in breeding season (April to August),sex ratio was correlated with the amount of precipitation (in the months with a precipitation less than 5 mm or more than 40 mm,the amount of precipitation of these months was significant correlated negatively with the sex ratio in next month (r=-0.764,P<0.01);5) the sex ratio did not related to the temperature.
Effect of the population densities of plateau zokor (Myospalax baileyi) in six density grades selected in alpine meadow of Haibei,Qinghai Province on biomass,structure and succession of plant communities was examined quantitatively with data collected in May and August of 1995 and 1996.Species composition,biomass,recovering rate of plants after be covered by mounds among six grades showed strong changes.The species numbers,total biomass of aboveground and monocotyledon biomass showed significantly negative correlation with population density,respectively.However,there was significantly positive correlation between the population density of plateau zokor and the log value of bicotyledons percentage of total biomass.As the population density of plateau zokor increased,the importance value of monocotyledons decreased significantly.However,some bicotyledons which contain second chemical compounds increased rapidly,the importance value of some plants which have strong roots became the biggest in plant community while zokor density was in the middle grade.The important value and biomass of grasses increased significantly,but the biomass of total plants didnt increase after some of zokor population were removed.
Through sampleplot investigation method,individual numbers and biomass of ant community in Xishuangbanna are determined,and daily and annual amount of soil and organic matters transported by ants are calculated separately.Oecophylla smaragdina (Fabricius) nests on 45.5% crowns of rubber trees and the latter is well protected.The total area of Xishuangbanna District is 19.690 km[2],in which Xishuangbanna Nature Reserve occupied 12.7%.The individual number of ants in this area is quite considerable.The total individual number of ants in Xishuangbanna Nature Reserve is 5.2×10[12],the respective biomass is 1.04×10[4] t,which equal to the total biomass of 3467 Asian elephants.And the annual amount of soil and organic matters they transported is 1.5×10[8] t.The total individual number of ants in the whole Xishuangbanna District is 5.2×10[13],and the respective biomass is 1.04×10[5] t,which equal to the total biomass of 34667 Asian elephants.The annual amount of soil and organic matters transported by these ants is 1.5×10[9] t.
From early Cambrian to early Jurassic,Xishuangbanna Oldland and Burma Oldland formed a whole oldland,and had the same history of species origin and evolution.But Xishuangbanna Oldland sank under the sea twice in late Carboniferous and middle and late Jurassic,all achievements in species origin and evolution were spoiled.The ants originated in middle and late Cretaceous or even earlier,and differentiated greatly in Palaeogene.To early Cretaceous,Xishuangbanna Oldland connected with Burma and China Oldlands,and never sank again from then on.So the species of Xishuangbanna Oldland were immigrated from Burma and China Oldlands since that time.To the initial stage of Himalayan Movement in Palaeogene,the northwest to southeast trend Western Yunnan Basin disappeared.Southwestern,southern and central China formed a uniform continent with similar landforms,and this provided a convenient condition for the interflow of species in west-east and north-south directions.At the same period,the India subcontinent jointed to the Asian continent,species of the two continents began to exchange extensively.To the later stage of Himalayan Movement in early Pleistocene of Quaternary,the continent north of Simao raised up distinctly,and species of Xishuangbanna divided from the fauna of China,but maintained close interflow in the west,south and east directions.To the middle and late Pleistocene of Quaternary,along with the formation of the Hengduanshan Mountains,Xishuangbanna area was correspondingly weakly raised up,and the complicated and varied landforms and climates in this area were gradually formed.The change of environment led to differentiation of species,and Xishuangbanna area became a distinct center for species differentiation.
An investigation on the fauna and ecology of fleas in the Cangshan Mountain and Erhai Lake Nature Reserve of Dali was carried out from 1992 to 1997.A total of 3 241 individuals belonging to 39 species,21 genera and 5 families was collected.The species diversity,evenness and ecological dominance indices of fleas communities in 7 main ecological environments were measured and compared.According to the investigation,the stability of flea communities is the highest in the coniferous and broadleaf mixed forest and the lowest in cultivated area.The vertical distribution of 39 species of fleas was investigated on both eastern and westsern slope of Cangshan Mountain.21 species (53.84%) belong to Palaearctic realm,16 species (41.03%) belong to Oriental realm,and 2 species (6.06%) are wide spread species.The elevation of 3 100 m (in Cooltemperate coniferous and broadleaf mixed forest) was the dividing line between the two realms in Cangshan Mountain.The authors cosider that delimiting the boundary line between Palaearctic and Oriental Regions in Hengduan Mountains of Southwestern China should base on the altitude,and the boundary line corresponds to the distributional band of the Cooltemperate coniferous and broadleaf mixed forest in this area.
Tricodons on the messenger RNA nucleotide sequence decide the amino acid sequence of their encoded protein.However,the rate with which the mRNA is translated in ribosome depends on several parameters such as different synonymous codon usage,codonanticodon interactions,codon context and different secondary structures in mRNA.These parameters also affect cotranslational folding and assembly of protein structure.That suggests the existence of the correlation between the sequence and structure of mRNA and protein structure.
The studies on resting eggs of freshwater rotifer were reviewed in this paper.Both the ecological significance of difference for hatching pattern of resting eggs and the effects of environmental conditions (such as temperature,photoperiod,strage condition of resting eggs,and physiological characteristic of mother rotifer) on hatching of freshwater rotifer resting eggs were summarized.The suddenly change of temperature could induce the resting eggs hatched.The effect of light on hatching is different among several species of rotifers.Mother rotifers diet and resting eggs storing condition influenced the hatching rate of resting eggs.