留言板

尊敬的读者、作者、审稿人, 关于本刊的投稿、审稿、编辑和出版的任何问题, 您可以本页添加留言。我们将尽快给您答复。谢谢您的支持!

姓名
邮箱
手机号码
标题
留言内容
验证码

1998年  第19卷  第5期

显示方式:
研究论文
In this study,non-radioactive Digoxigenin labeled ribosomal DNA(rDNA) probes were used for Southern blotting analysis to study the molecular phylogeny of the giant panda and related species.Restriction maps in the regions of rDNA spacers were compared between giant panda (Ailuropoda melanoleuca),lesser panda (Ailurus fulgens),Asiatic black bear (Selenarctos thibetanus),sun bear (Helarctos malayanus),raccoon (Procyon lotor) and lynx (Felis lynx).Phylogenetic trees for these species were constructed using maximum likelihood and parsimony method.The results show that in respect to rDNA RFLPs,the giant panda is more closely related to bear than to lesser panda;while the lesser panda is slightly related to the raccoon.
scent marks secreted by giant pandas may function as communication among individuals.We collected nine scent mark samples from seven giant pandas with different sampling methods.DNAs were successfully prepared with INSTAGENE kit.The mitochondrial DNA Dloop,cytochrome b gene and Thr-tRNA gene regions were amplified and the PCR products were purified and sequenced.Our results suggest that DNA from scent marks can be obtained from samples collected with different methods.A cotton stick is a best sampling way compared with other methods.Our work shows a new simple and efficient DNA source for studying on genetic diversity of giant pandas.
Analysis of the secondary structures of mRNAs which encode mature peptides shows that the location of each codon in mRNA secondary structure has a trend,which appears to be in agreement with the conformational property of the corresponding amino acid to some extent.Most of the codons that encode hydrophobic amino acids are located in stable stem regions of mRNA secondary structures,and vice versa,most of the codons that encode hydrophilic amino acids are located in flexible loop regions.This result supports the recent conclusion that there may be the information transfer between the three-dimensional structures of mRNA and the encoded protein.
The late spermatid of ovoviviparous teleost,Sebastiscus marmoratus (Cuvier et Valenciennes) possessed the approximate morphology of mature spermatozoon.The dorsal side of the nucleus was flat wheras its ventral side protruded outwards slightly.The chromatin condensed into wads.At its ventral part and posterior end,the chromatin was more compacted.The centriolar complex consisted of proximal centriole and basal body.The proximal centriole was perpendicular to the basal body,thus,the complex was L-shaped.A centriolar adjunct stretched out of the proximal centriole and pointed towards the dorsal side of the nucleus.The centriolar adjunct was composed of 9 microtubules.They formed cylinder-shape as the axoneme.During the process of transforming into spermatozoon,the centriolar adjunct and proximal centriole shrank back in succession,and finally disappeared completely.At the same time,the changes of the shape of the posterior end of the nucleus took place.The disappearing of the centriolar adjunct and proximal centriole in succession might be considered as a sign of being mature completely of the spermatid.The centriolar complex of the spermatozoon consisted of basal body and basal body cap which was between the basal body and the nuclear membrane.The sleeve was connected to the posterior end of the nucleus.There were about 30-40 mitochondria in the sleeve.The flagellum stretched out of the central space of the sleeve.The central structure of the flagellum was axoneme.There was one lateral fin at each side of the axoneme.At the proximal piece of the flagellum the lateral fins beside the axoneme were broad and asymmetrical.
In physiological (10 mmol/L Ca[2+])or low calcium saline (0.25 mmol/L Ca[2+]) bumps were evoked by dim continuous light (6×106[9]×10[6] photons/cm2; 10 s) in Limulus polyphemus ventral nerve photoreceptors.The photoreceptor was dark-adapted or weakly lightadapted by a 0.5 ms conditioning flash (9×10[9] photons/cm[2]),2.5 s prior to the continuous illumination.In 10 mmol/L external calcium the mean size (current-time integral)of the bumps was(39.5±1.76)pC; the light adaptation caused a decrease to (10.5±2.29)pC (n=4).In low calcium saline the effect of light adaptation was not reduced.The conditioning flash caused a reduction of the average bump size from (92±18.7)pC to (29±3.04)pC.However,when in low calcium saline the photoreceptors were stimulated by a few strong flashes (6.4×10[14] photons/cm[2]) in order to exhaust the intracellular calcium stores,the effect of light adaptation by the conditioning flash was reduced.The light adaptation caused a reduction of the bump size from (81±10.1)pC to (41±3.74)pC.Injection of 1.2 mmol/L EGTA into the dark-adapted photoreceptors which were soaked by physiological saline almost abolished the effect of the light adaptation.Thus,we conclude that the illumination releases calcium from the organelles.The changes of the cytosolic calcium concentration decides the degree of the light adaptation of the photoreceptors.
Urine every 2 h in all day was consecutively collected from normal and with suprachiasmatic ucleus (SCN) lesions of tree shrews.The circadian rhythm of urination was analysed.The results showed that there was obvious circadian rhythm of urination in normal tree shrews.Uric amount of the day light was (88.52±15.40)% of the all day uric amount.The difference between day and night was rather significant.After SCN lesions,uric amount of the day was(62.86±18.18)% of the total uric amount of the all day.It showed that the circadian rhythm disappeared.In the meantime,the average uric amount of 24hour obviously increased and the uric amount increased at night.It suggested that SCN was an important oscillator of circadian rhythm in the tree shrew.
Four Hu sheep fitted with chronic catheters at mesenteric vein and right hindquarter artery and vein were used to study the effect of clenbuterol on the amino acid net balance by means of determining the amino acid flow through their right hindquarter muscle.The results are as follows.In the control period,the total amino acid flows of the right hindquarter vein and artery were 4.54 mg/min and 5.48 mg/min,respectively.Compared with the control period,after injecting clenbuterol into the mesenteric vein,amino acid flow in right hindquarter vein and artery increased greatly (P<0.01):7.70 mg/min in the vein,9.61 mg/min in the artery,respectively.Of the 15 amino acids determined,in the experiment group,besides an obvious increase of the flow of all amino acids,a distinct increase could be found in the total quantity for 10 amino acids absorbed (Asp,Glu,Thr,Gly,Ala,Pro,Met,Val,Leu and Lys)and 3 amino acids released (Arg,His and Ser)by the hindquarter muscle (P<0.05).This indicated that clenbuterol could regulate amino acid net balance by altering the absorption or release of amino acids.
The study dealt with the biological characteristics and behavior of adult serpentine leafminer Liriomyza huidobrensis (Blanchard) in Kunming,Yunnan Province.Activities,emergence,feeding,oviposition and longevity of adults were studied.Behavior of probing,mating,feeding and oviposition were described.Before feeding,females use tarsus,ovipositor and proboscis to assess the suitability of host plants.When the population density is high,some males attack other coupled males.During courtship,males scrape stridulatory apparatus to attract mating.The results of this study will provide some valuable information for future control methods such as plantresistance,genetic control and mating disturbance.
Temperature-dependent development in the Asian corn borer,Ostrinia furnacalis (Guenee) was determined at nine constant temperatures between 10 ℃ and 34 ℃.Except for 10 ℃ development of all life stages occurred at the temperatures tested,however,mortality was significantly great at the extreme temperatures (12 ℃ and 34 ℃).Egg,larvae and pupae duration accounted for 17%,57% and 25% of total one of immature stage,respectively.Lower developmental thresholds estimated to be 10.38,10.06 and 11.07 ℃ for eggs,larvae and pupae,respectively.Upper limited thresholds were 28.00,31.00 and 31.00 ℃ for eggs,larvae and pupae,respectively.The heat-unit requirements for egg stage were 79.15 degree-days,for larval stage were 339.73 degree-days,and for pupal stage were 128.82 degree-days,respectively.Overall,heat-unit requirements for development from egg to adult were 539.91 degree-days between lower developmental threshold 10.35 ℃ and upper limited threshold 32 ℃.
From 6 typical zones in China 290 species of soil protozoa were identified.According to their feeding habits or the trophic patterns,the soil protozoa could be divided into 8 functionaltrophic groups,namely autotrophs,bacterivores,carnivores,detribivores,fungivores,herbivores,omnivores and saprotrophs.The feeding habits of various taxonomic groups of the soil protozoa were analysed and discussed.
This paper describes a new species of the rock agamid genus Laudakia.The new species is closely similar to L.tuberculata (Hardwicke et Gray),but the new species differs from the latter in that:1)nostril is situated in center of elliptic nasal,directing outwards and rearwards;2)one supranasal;3)superciliary ridge poorly developed,blunt and not everting upwards;4)dorsum and flanks with many small,light-colored spots,the large,conic scales scattered on flanks are not situated in those spots.
An important field of human genome project—the problem of ethics,law and sociology in the genome study,drew peoples widespread attention.This article preliminarily studies on the problem from the following aspects:the existence and development of human,the ethics and law problem in the interrelationship among human,nature and other species.