2004 Vol. 25, No. 1
The stable isotope approach is based on the fact that naturally occurring stable isotope ratios in consumer tissues can be related to those in consumers diets.Changes in,or fractionation of,stable carbon isotope ratios (C/C) occur with trophic level and are of the order of 1‰-2‰.Thus,isotope measurement of consumers tissues can reveal information about their ingested foods in ecosystems that are relatively simple.Determination of stable carbon isotope signatures in the alpine meadow ecosystem demonstrated that the ecosystem was composed of five main food chains,one was threenoded food chain characterized by "plants → small mammals → raptors (or carnivorous mammals)";two each were twonoded characterized by "plants → vegetarian passerine birds or livestock";and two each were fournoded and composed of "plants → insects → passerine birds → raptors (or carnivorous mammals)" or "plants → insects → amphibians → raptors (or carnivorous mammals)",respectively.The maximum length of food chain in the alpine meadow ecosystem was 3.53,which was grossly equal to maximum node number,I.e.,4.In summary,stable carbon isotope ratios can be used as a proxy to analyze food chains and food webs in the alpine meadow ecosystems.
Using pitfall traps,we built up 20 plots in the Eastern Hengduan Mountain Region,Southwest China,to compare the composition and distribution of litter-layer beetle communities among managed secondary forests (MSF) of plantation after clear-cutting,unmanaged secondary forests (USF) surrounding by farmland after clear-cutting,contiguous natural Abies forests (NAF),and contiguous natural Rhododendron elfin forests (NRF).Based on principal component analysis (PCA) and cluster analysis of species and individuals of litter-layer beetles,we discussed the effects of clear-cutting and management practices.A total of 4 292 individuals representing 24 families were collected between July 8 and July 14,2001.Of these,individuals of the family Carabidae take 46.8% of the total,Agyrtidae 13.1%,Staphylinidae 11.4%,and Scarabaeidae,Curculionidae and Tenebrionidae each more than 5%.These six families can be considered as common groups in the study area.The individuals of Carabidae were significantly more abundant in NRF than those in the other forests,and significantly sparser in USF than those in the other forests.Agyrtidae was found more frequently in two uncut natural forests than in two secondary forests after clear-cutting.More individuals of Tenebrionidae were found in NRF than those in other forests.Significantly more individuals of Cantharidae were trapped in NAF and MSF than in USF.Elateridae was found significantly more frequently in USF than in MSF and NAF.The individuals of Curculionidae were more abundant in MSF and NRF than in USF.More individuals of Chrysomelidae were trapped in NRF than in USF.Beetle capture per 100 traps per day was gradually increased from USF,MSF,NAF to NRF,but evenness was opposite.MSF had the highest species richness and diversity values.USF and NRF had the lowest values of richness and diversity,respectively.Principal component analysis and cluster analysis showed that beetle community of USF was different from those of the other forest types;although the beetle community of MSF was similar to two uncut natural forests,the similarity between MSF and NAF was much low.Based on these results,we conclude managed plantation after clear-cutting contribute to the re-establishment of the diversity of litter-layer beetle assemblages in Eastern Hengduan Mountain Region.
Five adult and two young female bats of Rhinolophus pearsoni were captured in Mingu town,Zhenfeng County of Guizhou Province.Their echolocation calls were received with ultrasound detector(D980,ULTRASOUND DETECTOR),read out at one-tenth of the original speed,and then recorded to computer.Batsound 3.10 software was used to analyze the recorded echolocation calls.The result showed that the adult bat emitted FM-CF-FM calls often with 2-3 harmonics,the calls dominant frequency,pulse duration and interpulse interval were 56.80±0.62 kHz,34.62±5.29 ms and 86.50±19.72 ms at fly,and 58.05±0.24 kHz,41.08±5.87 ms and 117.29±66.44 ms at hang,respectively,and duty cycle was (44.06±12.58)% at fly and (46.00±24.25)% at hang.The young bat emitted CF-FM calls with 5-8 harmonics.The calls dominant frequency of the young was lower,FM bandwidth was narrower,pulse duration and interpulse interval were shorter,and duty cycle was lower than those of the adult.It is suggested that the echolocation call was correlated with the age in bats R.pearsoni.The adult call responded for detecting the information of food and surroundings,and the young one was for communicating with its mother.
During the winter and summer of 2000-2002,four surveys with a total of 17 transects were conducted in agricultural area of all suburb districts/counties in Shanghai City.Species compositions,numbers,occurrence frequency of birds and habitat factors were recorded.Following these surveys,density,diversity,evenness,predominance,biomass,relative important value and their relationships with habitats were analyzed.In total,76 species,which belong to 13 orders,26 families,were recorded.The average density of birds is 5.19 ind./hm,the Shannon-Wiener index (H) is 1.8742.Five species are predominant species,I.e.Tree Sparrow (Passer montanu),House Swallow (Hirundo rustica),Rufous-backed Shrike (Lanius schach),White Wagtail (Motacilla alba) and Chinese Bulbul (Pycnonotus sinensis).25 species are waterfowl (most commonly seen are Nycticorax nyticorax and Egretta garetta).Compared with other areas of Shanghai,species density is higher,while diversity is lower.Counts of several species,such as Hirundo rustica,Pycnonotus sinensis and Passer montanus,Lanius schach,significantly outnumber that of other species.The results showed that species richness correlated positively with the area of wasteland,negatively with severity of pollution,and has no significant correlation with forest area,density of population and area of water,etc.It is concluded that wasteland is very important for keeping diversity of birds in agriculture area.
Two female and one male healthy adult Chinese alligators (Alligator sinensis) from Anhui Research Center for Chinese Alligator Reproduction were chosen by the veterinarians examination,and released with collars at Hongxing reservoir of Xuanzhou in Anhui Province on April 27th,2003.Radio telemetry,direct observation by binoculars in daytime and spotlight night counting in night-time were used to find out their activity area and movement pattern,and totally 372 movement points for them were recorded during an early period of four weeks.The results show that each individual has its own steady activity area after 3 to 14 days released;the male has a relative larger activity area and a larger change of daily movement area than those of the females;they are apt to choose the bank edge with good condition of vegetation coverage for live.The alligators released conflict with native ones in the reservoir occasionally,showing territory characteristics of this species.
The present study aimed to examine four cryoprotectants:glycerol,dimethyl sulfoxide,ethylene glycol and propylene glycol on rhesus monkey sperm cryopreservation.Frozen-thawed sperm cryo-survival and function was evaluated by sperm motility,plasma membrane integrity and acrosome integrity,and sperm plasma membrane and acrosome status was determined by nuclei stain Hoechst 33258 and Fluorescein isothiocyanate-conjugated peanut agglutinin (FITC-PNA).The result showed that:for the ability of protection on post-thaw sperm motility,glycerol (47.3±5.7%) and ethylene glycol (44.8±6.7%)> dimethyl sulfoxide (22.9±0.9%)> ethylene glycol (0±0%);for the ability of protection on sperm plasma membrane integrity,glycerol (54.8±3.2%) and ethylene glycol (54.0±6.7%)> dimethyl sulfoxide (37.5±7.0%)> ethylene glycol (28.3±6.5%);for the ability of protection on sperm acrosome integrity,glycerol (82.2±2.4%) and ethylene glycol (82.4±2.4%)> dimethyl sulfoxide (68.7±5.7%) and ethylene glycol (72.3±3.5%) (P<0.05).The results indicate that cryoprotective effects of various penetrating cryoprotectants are different.Dimethyl sulfoxide and propylene glycol are not suitable for rhesus monkey sperm freezing,especially propylene glycol.Ethylene glycol with similar cryoprotective properties to glycerol could be successfully used in the cryopreservation of rhesus monkey spermatozoa.
The 60 juvenile soft-shelled turtles (Pelodiscus sinensis) obtained from a commercial farm were acclimated in laboratory for three weeks.The five groups juvenile turtles ［one control group ? and four experimented groups (Ⅰ,Ⅱ,Ⅲ and Ⅳ)］ were fed with V[c] and V[E] supplementation at the dosages of 0 and 0,250 and 50,2 500 and 50,250 and 250,2 500 and 250 mg/kg diets,respectively.There were two replicates per group.After feeding 4 weeks,half turtles per group were treat with acid-stress for 24 h.The blood in turtles were collected,and the percentage phagocytic rate of blood cell was analyzed by counting under microscope;serum bacteriolytic activity,bactericidal activity,levels of complement C3 and C4 were analyzed by transmission colorimetric method.The results showed:1)the phagocytic rates of blood cell in stressed C significantly lowered compared with non-stressed C,while there were no significant changes in the other four groups of Ⅰ-Ⅳ between stressed and non-stressed turtles;serum bacteriolytic activity and the level of complement C3 in the stressed C and Ⅰ significantly declined,while there were no significant changes in Ⅱ-Ⅳ compared with nonstress groups.Serum bactericidal activity in all stressed groups lowered (the three groups of C,Ⅰ and Ⅲ tremendously significantly lowered,and Ⅱ and Ⅳ significantly lowered).The levels of complement C4 in the stressed three groups of C,Ⅰ and Ⅲ were significantly declined,while the other stressed two groups of Ⅱ and Ⅳ had no significant change compared with non-stressed ones.2)Among of the acid stressed juvenile turtles,the phagocytic rate of blood cell,serum bacteriolytic activity,bactericidal activity and level of complement C3 in Ⅰ-Ⅳ were significantly higher than that in C,and Ⅳ was significantly higher than the other four groups.The bactericidal activity in Ⅱ was higher than both Ⅰ and Ⅲ.The level of complement C4 in C was significantly lower than those in Ⅰ-Ⅳ,while there was no significant difference among the four groups of Ⅰ-Ⅳ.The combination of Vc and VE had interaction effects on the phagocytic rate of blood cell,serum bacteriolytic activity,bactericidal activity and the level of complement C3 after acid stress,while no interaction effect of the two vitamins on complement C4 was observed.The results suggested that the combination of V[c] and V[E] significantly improved anti-acid stress ability in soft-shelled turtles,and alleviated or partly alleviate the adverse effects caused due to acid stress.
The growth trial of a 56-day period was conducted at 30 ℃ to investigate the effect of ration on growth and feed conversion efficiency in juveniles Trionyx sinensis,which initial body weights ranged from 28.66 to 53.37 g.They were fed commercial soft-shelled turtle diet twice a day at five ration levels (starvation,1%,2%,4% and satiation).ANOVA showed that specific growth rate (SGR) and conversion efficiency (K) were significantly affected by the ration level.SGR increased quadratically with increasing ration,and the relationship between SGR for dry matter (SGR[d]) and ration level (RL) could be expressed as the follow:SGR[d]=-0.0832RL+1.0795RL-1.8779(n=25,r=0.906,F=105.46).The maximum SGR for wet matter,dry matter,protein and energy appeared when ration levels were 6.97%,6.49%,6.08% and 6.34%,respectively.All Ks at 1% ration group were significantly lower than those at 2% and 4%,and Ks for dry matter and energy were lower than the satiation;Ks for dry matter and energy at 2% were significantly higher than those at the satiation.
The movement way of Lophophorus sclateri was directly observed at Danaozi in Mt.Gaoligongshan in Januaries of 2002 and 2003,and habitat preference of the pheasant was sampled by transect and quadrant methods.The pheasant usually glided down,and always walked up.Three sleeping sites were found on steep slopes with high canopy density,and close to the valley.The pheasant shifted down in winter,which may be related to heavier snow in higher locations,resulting in a dense use of the belt close to the valley.The movement way and pattern of habitat use are clearly bound to maximize foraging effectiveness and minimize energy expenditure.
The proliferation,development and maturation of ovarian germ cells are regulated by multiple hormones,among which gonadotropins play a key role.In this study a germ-somatic cell coculture model of 18-day-old chicken embryo ovarian cells was established to evaluate effects of follicle-stimulating hormone (FSH) and 17β-estradiol (E) alone or in combination on germ cell proliferation.Results showed that FSH (0.25-1 IU/mL) and E(10-1000 ng/mL) both showed an notable increment in germ cells number after 48 h treatment.Furthermore,FSH manifested a synergistic effect with E in stimulating germ cell proliferation.These results indicated that FSH might interact with estrogen to promote embryonic ovarian germ cell proliferation.FSH might exert its action by stimulating the synthesis of estrogen or expression of its receptors.
The spermatozoa ultrastructure of Scapharca subcrenata and Barbatia virescens was comparatively investigated by transmission electron microscope.The acrosome of Scapharca subcrenata spermatozoon is conical in shape,about half the length of the nucleus;there is no front nuclear pocket,but a posterior nuclear pocket exists;five (occasionally four) mitochondria are seen surrounding the distal centriole of the mid-piece;the end-piece of the sperm consists of the axoneme and its surrounding cytoplasm,and the axoneme has a typical "9+2" structure.The longitudinal section of the acrosome of Barbatia virescens is umbrella-like in shape,and the acrosome covers the front of nucleus,and is about 1/3 the length of the nucleus.The nucleus has both front and posterior nuclear pockets;five (occasionally six) mitochondria are seen surrounding the distal centriole in the cross sections;the structure of the end-piece of Barbatia virescens is the same as that of Scapharca subcrenata.In Arcidae,the morphology of acrosome,the presence of the front and posterior nuclear pockets,and the number of mitochondria in the mid-piece are the clues for understanding of the interspecifically evolutionary relationship.
The presence investigation and morphology observation of 5-HT endocrine cells have been carried out with the anti-5-HT serum by the method of the ABC immunhistochemical technique in the digestive tract of Elaphe dione.The results indicate that the distributive density of 5-HT cells is maximum in the duodenum and minimum in the cardiac part of stomach,and the density curve of 5-HT cells in gastrointestinal tract appears reverse "V".The shape of 5-HT endocrine cells is diverse.The cells in superior segment (esophagus,and stomach) are round or ellipse,and disperse the bottom of epithelial or between gland epithelial cells mainly;those in middle segment (duodenum,jejunum,and ileum) are tapering,shuttle and round,and disperse the bottom of epithelial or between epithelial cells mainly;those in inferior segment (rectum) are round and disperse the bottom of epithelial cells.The tapering cells always have one long processus extending to either the gut lumen or lamina propria,and perform exocrine or endocrine function;the shuttle cells have two long processuses,one extending to gut lumen,the other extending to lamin propria,and perform both exocrine and endocrine functions.
In this study,silkworm strain T6,tolerant to fluoride,and silkworm strain 733 xin,highly sensitive to fluoride,were used to construct the near-isogenic lines.300 random primers were used in RAPD amplification to DNAs of these lines.A molecular marker named S207 was found linked to the fluoride tolerance gene.Examination to F segregated individuals of the above lines verified that this molecular marker was reliable.Subsequently,the molecular marker was cloned into a T vector (pUCm-T) for sequencing.Comparing with sequences available in the GenBank showed that this molecular marker was novel.We plan to convert it into a SCAR marker to facilitate establishment of a molecular marker assisted breeding system.
In the 1960s,the neutral theory proposed by Kimura caused an unprecedented challenge to the classical Darwin s theory of natural selection.However,recent advances in evolutionary genetics have provided a great deal of evidence on the role played by natural selection at the DNA level.These progresses have been stemmed from the appearance of enormous DNA sequence data of populations and genomes as well as the development of theoretical population genetics.There are mainly two kinds of approaches to detect selection at the DNA level:intraspecific polymorphism tests and interspecific divergence tests.The former one is represented by Tajima s (1989) D test while the latter one is based on the principle that the intraspecific polymorphism should be consistent with the interspecific divergence under neutrality.These methods are usually called "neutrality tests" because the neutrality hypothesis is taken as the null hypothesis in the tests.They are important tools not only in solving the basic theoretical questions in evolutionary biology but also in interpreting data and results obtained in the studies of human genetics and bioinformatics.In this paper,we shall review the progresses in detecting natural selection at the DNA sequence level and introduce the basis and application of several widely used tests.
In mammal,sex determination and differentiation are the consequence of sequential expression and interaction between many transcription factors and growth factors.The expression of SRY initiates the male pathway and induces the expression of many male specific genes,such as SOX9,AMH etc.The expression of FOXL2 in the undifferentiated ovary,and WNT-4 and DAX1 in female pathway made it no longer to be regarded as default pathway.Sex determination in birds is also controlled by genetic factors.EFT1 (female) and DMRT1 (male) were recommended recently as possible candidate genes for sex determination in birds.Many reptiles exhibit typical temperature sex determination.Temperature regulates the estrogen level and the sexual dimorphic expression of DMRT1 and SOX9 in the embryonic gonads during temperature sensitive period.Sex determination in the majority of amphibians is probably controlled by environmental factors,however,genetic factors such as DMRT1 and DAX1 may be involved in the differentiation of testis.Mechanisms of sex determination and differentiation vary considerably in fish.Many factors,especially sex steroidal hormones,were involved in the process.DMY,isolated by positional cloning in medaka,was regarded as the first sex-determining gene in non-mammals.All these seem to indicate that molecular mechanisms of vertebrate sex determination and differentiation are diversified.