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2000年  第21卷  第6期

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研究论文
Partial DNA sequences of mitochondrial 12S rRNA gene from Lipotes vexillifer,Platanista gangetica,and Pontoporia blainvillei,were amplified and determined to address the systematics of river dolphins.The sequence divergence among different genera of river dolphins,estimated either by transition+transversion or transversion only,is greater than those among other odontocete families,far greater than those among families Delphinidae,Monodontidae,and Phocoenidae within superfamily Delphinoidea.Thus,the river dolphin genera should be referred into different families,I.e.Lipotidae,Platanistidae,Iniidae,and Pontoporiidae.The phylogenetic analysis by using neighbor-joining method (NJ) and maximum parsimony method (MP) suggested that the Platanistidae was the earliest divergent clade in the cetaceans,whereas the other three river dolphin families constituted a monophyletic group having sister relationship with Delphinoidea.The phylogeny of river dolphins should be polyphyletic,rather than monophyletic or paraphyletic.The Platanistidae should be referred into a separated superfamily Platanistoidea,whereas the superfamily classification of other three river dolphin families should be further studied.
The mitochondrial DNAs (mtDNAs) from liver of C.auratus red var.,F[1] hybrids of red crucian carp (♀)×common carp (♂),C.auratus cuvieri and C.auratus auratus and ovary of C.auratus auratus were isolated and purified by the means of differential centrifugation and nuclease digestion.After having been digested by 9 restriction endonucleases (EcoRⅠ,HindⅢ,PstⅠ,BglⅡ,BamHⅠ,XhoⅠ,XbaⅠ,SalⅠ and KpnⅠ),the mtDNAs were analysed by using agarose gel electrophoresis.The results showed that PstⅠ,KpnⅠ and BglⅡ were the restriction fragments length polymorphism among four strains,but without the polymorphism within strains.The mitochondrial DNA size was about 16.19 kb in C.auratus red var,16.02 kb in hybrids,16.60 kb in C.auratus cuvieri and 16.06 kb in C.auratus auratus respectively.According the proportion of shared restriction fragments,the genetic distances between strains were calculated.The results manifested that the genetic distance was the smallest between C.auratus red var.and its filial generation hybrids,and that mtDNA followed the character of matrilinear inheritance.
Localization and expression of GnRH receptor (GnRHR) mRNA in the nervous system,Hatscheks pit and gonads of amphioxus,Branchiostoma belcheri,were investigated immunohistochemically using digoxigenin-labled oligonycleotide probe.The results showed that the nerve cells in midbrain and nerve tuber,the epithelia cells of Hatscheks pit and germocyte in testis and ovary of different development stages had GnRHR mRNA hybridization signal.It was worthwhile noting that some strong GnRHR mRNA hybridization signal were found for the first time in the funnel-like structure,a part of midbrain extension.The signal substance distributed in the cytoplasm,but the nucleus showed negative reaction.These results in dicated that the nervous system,Hatscheks pit and gonads of amphioxus were all capable of synthesizing GnRH receptors,which acted as target cells of GnRH in the nervous system,Hatscheks pit and gonads.Thus,the present study provided an authentic proof that GnRH might stimulate the secretory activity of Hatscheks pit epithelia cells and regulate gonadal development and maturation and reproduction activity on molecular level.It was suggested that the infundibulum-like structure might have two physiological functions:1) to act as a "transformation station" mediating the informative transfer and regulation between brain and Hatscheks pit;2)to be a regulation center to stimulate or inhibit the secretory act ivity of Hatscheks pit.
To understand the regulatory mechanisms of gonadotropin secretion in Rana rugulosa,this study investigated the effects of dopamine (DA),estradiol (E[2]) and testosterone (T) on the in vitro release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the pituitary fragments of female Rana rugulosa using a static incubation system and radio-immunoassay (RIA).The results indicated that DA at the concentration from 0.1 μmol/L to 10 μmol/L inhibited the release of LH and FSH from the pituitary fragments of sexually pre-mature or hibernating individuals,and the inhibitory effects enhanced with increasing concentrations of DA.E[2] at 1 μmol/L and 10 μmol/L significantly stimulated the release of LH of sexually pre-mature individuals,but inhibited their FSH release at 0.1 μmol/L to 10 μmol/L;T had no obvious effects on their FSH release,but significantly inhibited their LH release at 10 μmol/L.Neither E[2] nor T,at the concentration from 0.1 μmol/L to 100 μmol/L,had obvious effects on the release of LH and FSH of hibernating individuals.The data suggest that DA and sexual steroids may have direct regulatory actions on LH and FSH release at the pituitary level in Rana rugulosa,and the action of sexual steroids may relate to the gonadal development stages (seasons).
Cumulus oocyte complexs (COC) were recovered from abattoir cow ovaries collected from slaughterhouse.Then,They were matured and fertilized in TCM199 with 10% BCS.Later on,the one cell embryos were cultured in two culture systems:1)modified TCM199 over a buffalo rat liver (BRL) monolayer co-culture;2)Two stage semi-defined culture system [hamster embryo culture medium with 11 amino acids (HECM-6) followed by tissue culture medium 199+10% bovine calf serum].The results showed that HECM-6/mTCM199 system could improved embryo development to the morula or blastocyst stage higher (50%) than that in BRL/mTCM199 system (41%,P<0.01).This results suggested that HECM-6/mTCM199 two-stage semidefined culture system could provide a significant benefit for the early bovine embryo development,which might be related with glucose concentration and amino acids components in the medium.
Metabolic rate,body temperature,and thermal conductance of greater long-tailed hamster (Cricetulus triton) from the farmland in Hebei Province were determined at a temperature range of 5-36 ℃.Oxygen consumption was measured by using closed circuit respirometer and temperature was controlled by water bath.The thermal neutral zone was 29-31 ℃.Within the temperature range of 5-31 ℃,hamsters could keep their body temperature stable with mean value at (36.7±0.1)℃.Mean basal metabolic rate within thermal neutrality was (1.23±0.02) mLO[2]/(g·h).Total thermal conductance was kept stable within the temperature range 5-15 ℃ with mean value at (0.12±0.00)mLO[2]/(g·h·℃).The properties of the ecophysiology for greater long-tailed hamster were:1)metabolic rate was higher than the predicted value based on the allometric equation of total eutherian mammals,lower than the predicted value of rodent species,and slight higher than the predicted value of cricetid rodents,higher than predicted value of seed-eaters and similar to the predicted value of grazing species;2)the body temperature was relatively low;3)thermal conductance was relatively higher than the predicted value based on their body weight.All these characteristics were close related to their living habits such as nocturnal,mainly feeding on crop seeds and small fraction of young crop leaves and insects,burrowing,and solitary.Greater long-tailed hamster is distributed dominantly in northern Changjiang River in China and they are not likely to survive in extreme dry area and alpine area.Thus,we proposed that ecophysiological characteristics of greater long-tailed hamsters might constrain their distribution and extension to extreme desert or high altitude and cold region.
In this paper,the sound spectra of fidget calls,threatening calls,alarm calls and attack calls of the adult Gansu zokor (Myospalax cansus) were analysed.The results indicate that the Gansu zokors fidget calls occurred in sleep occasionally.The sound spectrum of fidget call is simple,there is only one energy range (936-1833 Hz),the main peak frequency (MPF)was 1501 Hz,the duration 366 μs,and the interval 135 μs.The Gansu zokor gave out threatening calls when two individuals encounter.The threatening calls have two energy ranges (58.5-2671.5 Hz,3237-5518.5 Hz) and the MPF was 1170-1287 Hz.The duration of the females threatening call was longer than that of male.The interval of threatening calls of female and male were 254 μs and 315 μs respectively.When the zokor was in danger or was captured,it gave out alarm calls.This kind of calls have two energy ranges also (1677- 2340 Hz,3315-4816 Hz).The frequency of alarm call is the highest of the four kinds of calls,MPF is 3783 Hz and the duration is 1266.67 μs.The zokor sounded attack calls while attacking other individuals.The sonograms of attacking calls were complicated than those of other calls and there were three energy ranges.Two are located in low frequency range (97.5-975 Hz,975-2262 Hz) and the rest one located in medium frequency range (164.5-5148 Hz).Average MPF is 1228.5 Hz.The duration of male was 1071 μs,while the females was 564 μs.The intervals of female was 288 μs,while the males was 231 μs.The frequencies of Gansu zokors calls are located in the low or medium energy ranges,this is similar to the other subterranean rodents calls.
Otis undulata macqueenii and Otis tarda tarda are rare and endangered species in the world,and listed in the first category protected animal in China.This paper deals with our studies on the ultrastructural eggshell of these two species with scanning electron microscopy. The microstructures of the eggshell of O.u.macqueenii and O.t.tarda are composed chiefly of inner shell membrane,outer shell membrane,cone layer,spongy layer and outer layer.Their characteristics are following: 1) Outer eggshell membrane layer Under the scanning electron microscopy the outer shell membrane of both species appear dense mat fibre with some bud projections and interweave into net and arrange in many layers.There is also obvious difference between these two species.The diameter of the membrane fibre of O.t.tarda is wider than that of O.u.macqueenii,but the membrane fibre of O.u.macqueenii is much compacter than that of O.t.tarda.In addition,the bud projections on shell membrane fibre of O.u.macqueenii are more profuse than those of O.t.tarda.2) Cone layer The cone knobs of the eggshell of O.u.macqueenii are arranged thickly in flower shape,while those of eggshell of O.t.tarda are arranged loosely in different shape and size and consist of several cone cores.3) Spongy layer The spongy layer is the hardest part of the eggshell.There are many gas-filled vesicular hole in this layer.4) Outer layer The outer surface of the eggshell of both Otis undulata macqueenii and Otis tarda tarda is rough and has many granules and many pore mouths in various size and appearance.The granules on the outer surface of eggshell of O.u.macqueenii are more than those of O.t.tarda.The pore mouths of the latter are less than those of the former,but larger.There is a protein membrane produced by oviduct to prevent bacterium and water loss.Results of the energy spectrometer show that the element component of eggshell is related with the habitat as well as the food.
This paper mainly studied the process of the external morphological character of Cherax qudricarinatus embryo from fertilization to incubation.This process is divided into cleavage stage,blastula,gastrula,egg-nauplius stage,egg-metanauplius stage,embryo with eye pigments formed stage and prehatching stage.The larval is similar to the adult on the morphological structure while it just has hatched.The whole incubation period of this species at 28 ℃ is about 39 days.
The palaearctic field mice (genus Apodemus) mainly have a palaearctic distribution and marginally occur in Oriental region in southern China and the Himalayas.Among Chinese Apodemus,A.orestes is often aligned with A.draco.This paper is designed to clarify the systematic problems of A.orestes based on 245 specimens collected in Wuliang Mountain,Central Yunnan.Of the specimens,147 with complete skulls have been used for multivariate and monovariate analyses.The principal component analysis gave out two groups,A.chevrieri and dracoorestes group,while the discriminant analysis showed that all specimens were correctly classified in A.chevrieri,A.draco and A.orestes with the former widely different from the latter two.An univariate analysis demonstrated that A.draco and A.orestes had significant difference in head and body length (t=78.359,P<0.001),tail length (t=71.555,P<0.001),the rate of tail length to head and body length (t=70.550,P<0.001),cranial breadth (t=75.886,P=0.025) and palatal bridge length (t=60.803,P=0.030).Apodemus draco has a wide distribution in Wuliang Mountain,which overlaps with A.chevrieri in lower elevations less than 2300 m in farmlands and jungle habitat,overlaps with A.orestes in higher elevations over 2450 m in forest habitat.Therefore,Apodemus orestes is a valid species.
Neobychowskyella chelicerus sp.nov (Fig.1) Type specimens:deposited in the Deparment of Biology,Yunnan Teachers University and Simao Teachers College.Host:Pseudecheneis sulcatus (McClelland) Location:Luozha River (Yunxian County,24°28′N,100°07′E),Western Yunnan,China.Description:Minute worm,body size 0.288-0.432×0.060-0.080,pharynx 0.024-0.032,7 pairs of marginal hooklets,4 pairs embryonic type and 3 pairs enlarged,0.025-0.035 in length,2 pairs of anchors;dorsal central large hooks:total length 0.048-0.050,basal portion 0.048-0.050,inner and outer roots not marked,point 0.008-0.010;ventral anchors:total length 0.025-0.026,basal portion 0.020-0.026,inner and outer roots not prominent,point 0.008-0.010.Connective plate a rhomboidal ring,0.006-0.015×0.046-0.051.Connective bars paired,0.004-0.008×0.039-0.048.Accessory pieces 0.004-0.005×0.032-0.035,with an additional chitineous stick,0.020-0.024 in length.Onchium a double striped anchor-like structure and with a crossed scissor-like piece anterior to it.Copulating tuba arched,0.088-0.100 in length,basal diameter 0.004-0.005;supporting apparatus a curved membranous piece with a circular opening on its middle,and through this opening the copulating tube passes.Vagina tubular,0.052-0.083.Egg 0.064-0.073×0.064-0.086.Description based on 5 mounted specimens.
What kind of prokaryotic cells did the eukaryotic cells originate from? This is an important basic biological problem,which has puzzled people for a long time.But in recent years,great achievements have been made to resolve such a problem due to the discovery and accumulating researches of archaebacteria.Here,similarities between archaebacteria and eukaryotic cells in many aspacts including DNA duplication,transcription,translation and histones,chromatin,proteasome were introduced.Finally,the evolutionary position of archaebacteria and their significance to origin of the eukaryotic cells were discussed.
The buff-breasted rat,which distributes in southeast Asia and China,is one of most important pests in China.The animal not only causes the damage on property,but also is related to many human infection diseases.This paper reviewed the existing data about the species in China,in terms of morphology,taxonomy,geographical distribution,behavior,population ecology,physiology and the control.The buff-breasted rat is mainly distributed in south China,and the population density of the rat is high in the south and low in the north.The rats northern most distribution is at 40°N.The temperature is one of the important factors that restrict the distribution of the animals.The suitable temperature range for the animals is 25-30 ℃.Therefore,the warming climate is perhaps most important reason for the spreading and the increase of the population densities of the rats in north China.Moreover,the traffic development is also responsible for the spreading of the animals.The changes of house structure cause the decrease of the population densities of the rats in south China.The rats in south China inhabit both in the buildings and on the farmland.However,the rats in north China mainly inhabit in the buildings.This phenomenon perhaps relates to the differences of the climate between the north and the south.Its breeding cha racteristics are also different between the north and the south.In the south,it breeds all year around and has two main breeding seasons.But it has only one breeding season in the north.Its population fluctuations result from breeding status.The chromosome diploid number is 2n=42,containing 13 pairs of telocentrics or subtelocentrics,7 pairs of smaller metacenteic and XY sex chromosomes.There are some disbutes on its taxonomy.It is considered generally that the species has two subspecies in China,R.flavipectus yunnauensis and R.flavipectu s flavipectus.Some scholars,however,insisted that the two subspecies should be considered as two species.Others even considered that the differences of the animals distributing all over China are not enough to divide the animal into two subspecies.Based on the present available literature,the animal is related to more than 10 human infection diseases in China.Changing the house structure is one of efficient ways to manage the animals.Anticoagulants are suggested to be used to control the animal.
Animal venoms are among the richest sources of toxins and pharmacologically active compounds that act on ion channels.At present,many novel pharmacological agents of great potential interests to pharmacologists and neuroscientists are being characterized from the venoms of reptiles,spiders,scorpions,sea anemones and cone snails.These toxins are widely used to elucidate the interrelationship between the structure/function of their targets.Many animal toxins are often of small size peptides,rich in disulfide bonds.They exert multiple functions acting on a variety of molecular targets,including ion channels,enzymes and receptors.With their high potency and selectivity to voltage-gated ion channels and their unique and simple three-dimensional folds,many low molecular toxins are often useful as a model to discover,design novel drug leads and to reveal potential therapeutic targets.The classification and specificity of animal toxins and their potency in drug exploitation were discussed.