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971.
Kan Wang Paul Drayton Bronwyn Frame Jim Dunwell John Thompson 《In vitro cellular & developmental biology. Plant》1995,31(2):101-104
A number of different methods, involving direct DNA delivery are now available for plant transformation. Here we review the most recently developed technique which involves the mixing of silicon carbide whiskers with plant cells and plasmid DNA. Fertile transgenic plants have now been produced using whisker-mediated transformation, and this method can now be considered as a simple, inexpensive alternative for plant transformation. A brief review on transformation of animal cells andChlamydomonas using whiskers technology is also included. 相似文献
972.
Francisco M. Pinto Yves Chupeau Vicente M. Cabrera 《In vitro cellular & developmental biology. Plant》1995,31(2):96-100
An efficient and easy method for genetic characterization of plant somatic hybrids is proposed. In a first qualitative approach,
four somatic hybrids and their parental species (Nicotiana tabacum andN. plumbaginifolia) were characterized by DNA fingerprinting and Random Amplification of Polymorphic DNA (RAPD). After this, a quantitative
estimation of the degree of parental contribution to the hybrids was carried out by means of a slot-blot analysis. Both qualitative
methods, showed one hybrid identical toN. tabacum, two almost identical toN. plumbaginifolia, and a fourth similar to this parental species, but with someN. tabacum admixture. The quantitative method, for the same hybrids, gave 83%, 7%, 7%, and 37%N. tabacum DNA contribution, respectively. 相似文献
973.
The fungal succession on pine cones on the floor ofPinus densiflora forest was investigated in the early decomposition process (within ca. 30% decrease in dry weight). The fungal flora was examined by both washing and surface-sterilization methods on artificially placed cones and naturally fallen cones. The decomposition rates of artificially placed cones were 0.081–0.082 yr–1. On withered cones still attached to the tree,Pestalotiopsis spp. were dominant. These fungi also occurred with higher frequencies after cones had lain on the floor and on cones in the L and FH horizons.Xylaria sp. andPhomopsis sp., which seem to colonize the interior of the tissue, occurred with higher frequencies on the cones on the tree, but their occurrence frequencies decreased after cones had lain on the forest floor. Conversely,Mortierella spp. andTrichoderma spp. newly occurred or their occurrence frequencies increased on lying cones. Of these,Trichoderma koningii increased rapidly and showed high occurrence frequencies.Thysanophora penicillioides, which prefers coniferous substrates, showed higher occurrence frequencies in the early stages of lying on the forest floor. On cones lying on the floor, the fungal flora did not significantly change during the investigation period. 相似文献
974.
John Beatty 《Biology & philosophy》1994,9(3):333-356
Ernst Mayr's distinction between “ultimate” and “proximate” causes is justly considered a major contribution to philosophy of biology. But how did Mayr come to this “philosophical” distinction, and what role did it play in his earlier “scientific” work? I address these issues by dividing Mayr's work into three careers or phases: 1) Mayr the naturalist/researcher, 2) Mayr the representative of and spokesman for evolutionary biology and systematics, and more recently 3) Mayr the historian and philosopher of biology. If we want to understand the role of the proximate/ultimate distinction in Mayr's more recent career as a philosopher and historian, then it helps to consider hisearlier use of the distinction, in the course of his research, and in his promotion of the professions of evolutionary biology and systematics. I believe that this approach would also shed light on some other important “philosophical” positions that Mayr has defended, including the distinction between “essentialism: and “population thinking.” 相似文献
975.
Richard W. Burkhardt Jr. 《Biology & philosophy》1994,9(3):359-371
Ernst Mayr's historical writings began in 1935 with his essay Bernard Altum and the territory theory and have continued up through his monumentalGrowth of Biological Thought (1982) and hisOne Long Argument: Charles Darwin and the Genesis of Modern Evolutionary Thought (1991). Sweeping in their scope, forceful in their interpretation, enlisted on behalf of the clarification of modern concepts and of a broad view of biology, these writings provide both insights and challenges for the historian of biology. Mayr's general intellectual formation was guided by the GermanBildung ideal, with its emphasis on synthetic and comprehensive knowledge. His understanding of how to write history was inspired further by the example of the historian of ideas Arthur Lovejoy. Some strengths and limitations of this approach are explored here through attention to Mayr's treatment of the French biologist J.-B. Lamarck. It is contended that Mayr's contributions to the history of biology are not restricted to his own very substantial historical writings but also include his encouragement of other scholars, his development of an invaluable archive of scientific correspondence, and his insistence that historians who write about evolution and related subjects acquire an adequate understanding of the principles of Darwinian biology.This paper was originally delivered at the biennial meeting of the International Society for the History, Philosophy, and Social Studies of Biology, held in Brandeis in July 1993, in the special session organized by John Greene on Ernst Mayr's contributions to systematics, evolutionary theory, and the history and philosophy of biology. The paper is presented here with only slight modifications of the original, oral presentation. As indicated in the text, a full assessment of Mayr's historical work, including situating that work in the context of Mayr's other work and contemporary developments in the history of science, would require a much more extensive study than I have been able to undertake here. 相似文献
976.
Andrew A. Potanin V. Vladyslav Olga S. Belokoneva Frederick W. Wiegel 《European biophysics journal : EBJ》1994,23(3):197-205
The process of ligand binding to a cluster of membrane-associated receptors is examined theoretically. The theoretical model proposed involves the diffusion of ligands from the solution to the disc-like cluster of receptors on the surface of the spherical cell. When the ligand hits the internal part of the disc-like cluster, it begins to move laterally until it leaves the disc through its outer surface or is bound by one of the receptors inside the disc. If the ligand leaves the cluster, it returns to the solution and hits the disc again after a certain period, etc. According to our model the transition from a diffusion-limited to a reaction-limited process of binding is determined by the dimensionless parameter Dt
c/a
2, where D is the lateral diffusion coefficient,t
c is the characteristic time of reaction, anda is the radius of the disc-like cluster. The forward rate constantk
f turns out to be a function of . Comparing the results of our calculations ofk
f with some experimental data we found that agreement is achieved at high , i.e. the process of ligand binding by clustered receptors is predominantly reaction-limited. 相似文献
977.
T. Shivashankar 《Journal of biosciences》1994,19(1):81-90
Scorpions arc generally non-social, solitary animals that interact with conspecifics at birth, courtship or predation only.
The present study reports the presence of advanced sub social behaviour inHeterometrus fulvipes Brunner and evaluates the importance of its burrowing as a cause for such social behaviour.Heterometrus fulvipes constructed deep angular burrows at the base of plants. Burrows provided (i) protection against predation, (ii) increased
availability of food and (iii) ideal microclimate for year round activity of the scorpions. No cannibalism was observed in
laboratory maintained colonies. The risk of predation and the difficult by immatures to dig tunnels during dry soil conditions
may have forced the mother and offspring to live together in the burrow for longer durations. The cohabitation of relative
offsprings transforms the burrow into a nest. The members of a colony exhibits division of labour for nest expansion and in
foraging. The mother communicates with the immatures through “Buzz” sound and may provide premasticated food. There is food
sharing also among colony members. All these behaviours indicate the presence of advanced sub social behaviour inHeterometrus fulvipes. 相似文献
978.
本文用Hela229细胞培养与单克隆抗体免疫荧光法对940例咽拭子及224例纤支镜取材标本进行肺炎衣原体分离鉴定。结果正常组、上呼吸道感染组、下呼吸道感染组、肺部肿瘤组的咽拭子标本分离率分别为0%(0/248),2.13%(10/468),2.1%(3/146),1.28%(1/78)。上呼吸道感染组和下呼吸道感染组的分离率均高于正常组和肺部肿瘤组。前二组与正常组的差异有显著性意义(P<0.05),与肿瘤组的差异无显著性意义(P>0.05)。下呼吸道感染组、肺部肿瘤组的纤支镜取材分离率分别为10.96%( 相似文献
979.
根瘤菌资源数据库(RRDB)的建立 总被引:1,自引:1,他引:0
在总结我室多年对根瘤菌资源调查与分类研究的基础上,建立了根瘤菌资源数据库(RRDB)。此库依据根瘤菌研究特点而设计,包括:基本信息、采集信息、保藏信息、回接信息、参考文献、性状信息、菌株说明等七个子库。目前收录了来自国内21个省或地区及国外部分研究单位提供的;并经全面性状分析与分类研究的286个菌株的信息,每个菌株设有寄主来源、固氮酶活性、碳源、氮源的利用等321个数据项。该库具有数据维护、查询检索、数据统计、输出打印等功能,引入并连接了聚类分析软件包-MINTS系统,可以满足当前研究的需要。 相似文献
980.
Rabindranath Ray Chinmay K. Panda Bimal K. Chakraborty Sheela Mukherji Kanakendu Chaudhury Jayashree Roychoudhury 《Molecular and cellular biochemistry》1994,131(1):67-73
Partial hepatectomy (P.H.) induces a partially synchronized growth response of liver under normal regulation of growth. In this phase changes in cellular morphology, radial distribution pattern of cells and other biological as well as major biochemical changes are well documented [24]. Here, we have shown that the cellular content of UsnRNAs altered during this proliferative phase as well. The level of spliceosomal UsnRNAs (U1, U2, U4–U6) gradually decreased by 30–50% upto 48 hrs of P.H. followed by gradual increase to reach the normal level within one month of P.H. The U3 snRNA level on the other hand, was nearly equal to that in normal liver at 48 hrs of P.H. but in 24 and 72 hrs of P.H. its level was high (4 fold) in contrast to that in other UsnRNAs. Thus, it is clear from our data that the level of all the six UsnRNAs decreased during 48 hrs of P.H. compared to that after first 24 hrs. This has been correlated in the kinetics of UsnRNAs' synthesis (in terms of labelling) in isolated hepatocytes, where the rate of labelling of all the six UsnRNAs increased 20–30% in 24 hrs regenerating hepatocytes (R.H.) followed by sharp decrease by 30–50% within next 24 hrs, compared to that in the normal hepatocytes. But from 72 hrs onwards in R.H. the rate of labelling of all the six UsnRNAs again increased by 30–50% (compared to that in normal hepatocytes) followed by decrease of their labelling-rate to reach the normal level in R.H. within one month of P.H. Thus, it may be concluded that the changes in UsnRNAs' level during the proliferative phase of liver regeneration may be either due to the alteration in the rate of synthesis (in terms of labelling) or along with it differential turn over rate; this phenomenon may have some consequences with the regenerative process of liver.This paper was published in Molecular and Cellular Biochemistry131:67–73, 1994. Kluwer Academic Publishers regret the publication of the only partly corrected version. 相似文献