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1.
The developmental study of the skull reveals the following views: The elapid chondrocranium represents a very advanced ophidian type. It more resembles the viperid chondrocranium than the colubrid one. The viperid chondrocranium is only very slightly more advanced than that of the Elapidae. The viperid osteocranium has progressed still further in the development of the poison apparatus than has the elapid osteocranium. The developmental study of the skull advocates the opinion that the family Colubridae has given rise to the family Elapidae, and the Elapidae (or at least the ancestral Elapidae) has given rise to the family Viperidae.  相似文献   

2.
The effect of Eresus niger spider venom on frog neuromuscular preparations has been studied using the intracellular microelectrodes. The spider venom has been found to block both spontaneous and elicited transmitter release and possesses the phospholipase activity. It has been suggested that the venom blocking synaptic transmission results from its phospholipase activity by analogy with the action of snake presynaptic neurotoxins.  相似文献   

3.
The heart rate and intraatrial latencies between epicardial electrograms from three sites of the right atrium have been studied during vagal stimulation in open-chest dogs. It has been shown that alterations of latencies started at a certain cardiac cycle length irrespective of pacing frequency. A transitional process of changes from a steady latency value in the control to another steady value during vagal stimulation has been observed. The transitional process has been simulated in experimental procedure in which two sites of the right atrium were paced at close and constant frequencies. To interpret the results obtained one-dimensional model of the sinus node has been constructed. According to the model, pacemaker shift within the sinus node results from a competition between two foci of automaticity with close intrinsic frequencies.  相似文献   

4.
Apparatus permitting to regulate the growth rate of turbidostat culture of microorganisms has been worked out. The process of adaptation of culture microorganisms to the medium acidity has been investigated by the stabilization of growth rate method. The correlation coefficients between adaptation time and changes of acid concentration in medium have been determined. The effect of aeration and density of microorganisms on the parameters of adaptation process has been considered. The conclusion concerning prospects of the growth rate stabilization method application for studying the regularities of culture microorganisms adaptation to the action of the stress has been made.  相似文献   

5.
While the definition of the 'genotype' has undergone dramatic changes in the transition from classical to molecular genetics, the definition of the 'phenotype' has remained for a long time within the classical framework. In addition, while the notion of the genotype has received significant attention from philosophers of biology, the notion of the phenotype has not. Recent developments in the technology of measuring gene-expression levels have made it possible to conceive of phenotypic traits in terms of levels of gene expression. We demonstrate that not only has this become possible but it has also become an actual practice. This suggests a significant change in our conception of the phenotype: as in the case of the 'genotype', phenotypes can now be conceived in quantitative and measurable terms on a comprehensive molecular level. We discuss in what sense gene expression profiles can be regarded as phenotypic traits and whether these traits are better described as a novel concept of phenotype or as an extension of the classical concept. We argue for an extension of the classical concept and call for an examination of the type of extension involved.  相似文献   

6.
The influence of medium acidity on the intensity of light-dependent antibacterial activity of chlorophyllides isolated from biomass of microscopic green alga Westella botryoides has been studied. This light-dependent antibacterial activity has been shown to be maximum at low pH values. The ability to suppress the bacterial growth under the action of light decreases in neutral and alkaline media. It has been concluded that the reason of increase of light-dependent antibacterial activity of chlorophyllides at low pH values is formation of pheophorbides out of them  相似文献   

7.
Chromosome preparations from peripheral blood cells of 117 subjects who took part in liquidation of Chernobyl NPP accident consequences in 1986 have been investigated. The number of chromosome aberrations has been shown to increase considerably. A short-term exposure has been found to be 5-7 times more effective than long-term one.  相似文献   

8.
Fragmentation of the pYT plasmid of the plague pathogen by ten restriction endonucleases has been studied. The evidence has been obtained in support of the possible presence of the movable genetic element containing a HindIII site within the plasmid pYT. The gene encoding the I fraction of the plague pathogen has been cloned. The physical map of the pYT plasmid has been constructed with the use of restriction endonucleases BamHI, XhoI, BstEII, SmaI, EcoRI, and HindIII. The fragment of the plasmid DNA coding for the synthesis of the plague pathogen fraction I has been mapped.  相似文献   

9.
Formation of different types of artifacts during amplification has been studied using different classes of molecular-genetic markers (Indel and SSR). It has been shown that DNA heteroduplexes are formed during amplification of heterozygous samples as fragments of both target genes and microsatellite loci. Electrophoresis of the amplification products of homozygous samples by microsatellite loci in native polyacrylamide gel has revealed specific additional fragments that do not belong to the class of heteroduplex DNA. It has been supposed that the additional fragments belong to a special type of homoduplex DNA—nonlinear homoduplexes. The analysis has revealed that the formation of nonlinear homoduplex DNA takes place on the 20–25 cycle of the PCR at the amplification of both experimental samples and individual DNA fragments cut from the gel.  相似文献   

10.
In a continuing study of protein-lipid interactions in egg yolk, the total apoprotein mixture (i.e. the 'apovitellenins') from the high-lipid, low-density lipoprotein (density 0.97 g/ml) of the yolk from hen's eggs has been isolated in a soluble form. By gel-filtration chromatography in 6M urea the mixture has been separated into several fractions from which three new low-molecular-weight proteins (I, Ia, and II), making up about 30% of the total, have been isolated. The most plentiful of these (I) consists of stable aggregates with several identical subunits each of molecular weight about 10 000. This protein is analogous to the principal protein from the corresponding lipoprotein of emu's egg yolk, i.e. emu's apovitellenin I. Hen's apovitellenin I has a slightly different amino acid composition from that of the emu; notably it contains a sulphydryl group. The hen's protein also forms more stable aggregates that are dissociated by detergent and by guanidine hydrochloride but are stable in urea. The molecular weight of Ia is similar to that of I and the amino acid composition is the same, with the exception that Ia has a higher proportion of amide groups. It aggregates less readily than I under the same conditions. The third new protein (II, 'hens's apovitellenin II') has a molecular weight of about 20 000. It has no tyrosine or methionine residues, but contains glucosamine and has several disulphide groups. It has been isolated in very small amount only.  相似文献   

11.
The growth of drug addiction has been noted in Nikolaev. This growth has not been stopped by methods based on the use of force. The results of work in accordance with the program "Harm Reduction" are presented. The program functions on the basis of the Charity Fund "Blahodiinist" and is intended for the prevention of the spread of HIV infection in groups of risk among injecting drug users and in other groups. The realization of the program includes provision of information material, reduction of harm in connection with the use of drugs by injection and the risk of getting HIV and sexually transmitted diseases. The analysis of the results has shown the effectiveness of the program (the frequency of using condoms has increased, the number of sex partners and the number of casual liaisons have dropped, the custom of using sterile syringes has been formed). Considering that during epidemics the coverage of not less than 70% of the representative of risk groups is necessary, the program should be realized on a greater scale to increase its effectiveness.  相似文献   

12.
The spatial variability of the vertical structure of bioluminescence intensity has been studied along the Crimean coast in the spring period. The location of a layer with a high intensity of bioluminescence has been determined and its dependence on hydrological characteristics and thermohaline structure of waters is shown. Structurization of the spatial variability of bioluminescence intensity has been made. Four regions that are distinguished by the pattern of the vertical distribution of the bioluminescence intensity have been distinguished in coastal waters of the Crimean Peninsula.  相似文献   

13.
Huang  Yi  Gu  Zili  Fan  Yang  Zhai  Guangxi  Zhao  Xiaogang  Sun  Qifeng  Shi  Yanbin  Lin  Guimei 《Purinergic signalling》2019,15(1):53-67
Purinergic Signalling - In recent years, immunotherapy has produced many unexpected breakthroughs in oncological therapy; however, it still has many deficiencies. For example, the number of...  相似文献   

14.
The ecological characteristics of the micrococcal community on the skin of the mammary glands of nulligravidae, pregnant and puerperant women have been studied. The species composition of the community, the population size and occurrence of each species, its participation in the dominant structure of the community have been determined. The comparative evaluation of its types has been made. A decrease in the dominating role of M. luteus in pregnant and puerperant women has been established. The tendency towards the normalization of the structure of the community in the postnatal period has been established.  相似文献   

15.
人类基因组及后基因组研究进展及其应用与开发研究现状   总被引:9,自引:0,他引:9  
人类对自身基因组的研究,随着人类基因组工作草图的绘制完成和对基因功能研究的深入已加快进入了实质性、关键性的开发利用阶段。本文概述了人类基因组及后基因组的研究进展及依此开展基因治疗及基因(组)药物研制等应用开发研究的现状。  相似文献   

16.
Genealogical approach to the formation of the winter wheat core collection   总被引:1,自引:0,他引:1  
The correctness of the genealogical approach to the estimation of genetic diversity has been substantiated. The approach implies a comparison of the estimates of similarity based on genetic markers and coefficients of parentage. A method of the application of the genealogical approach to the formation of the core collection has been developed. The adequacy of the core set has been estimated using Shannon's diversity index adapted for genetic profiles and the correlation between the distributions of ancestors' contributions. A core collection has been formed. This collection contains 25% of the accessions of the original winter wheat (Triticum aestivum L.) collection from the Czech Genebank and represents 70-76% of the intracluster diversity. A decrease in intercluster diversity has not been found in the core collection.  相似文献   

17.
18.
Journal of Molecular Histology - The distribution of mucosubstances in the glandular layer of the female portion of the spermoviduct ofDeroceras laevis has been investigated and an attempt has been...  相似文献   

19.
It has been found that bremazocine predominantly enhances the flexor reflex of the right hind limb, without affecting the left limb. The similarity of the visual data measuring the asymmetry of the pose and the asymmetry of EMG responses to painful stimulation has a high probability. No correlation between the asymmetry of the pose and EMG extensor activity has been found.  相似文献   

20.
Genealogical Approach to the Formation of the Winter Wheat Core Collection   总被引:3,自引:0,他引:3  
The correctness of the genealogical approach to the estimation of genetic diversity has been substantiated. The approach implies a comparison of the estimates of similarity based on genetic markers and coefficients of parentage. A method of the application of the genealogical approach to the formation of the core collection has been developed. The adequacy of the core set has been estimated using Shannon's diversity index adapted for genetic profiles and the correlation between the distributions of ancestors' contributions. A core collection has been formed. This collection contains 25% of the accessions of the entire winter wheat (Triticum aestivum L.) collection from the Czech Genebank and represents 70–76% of the within-cluster diversity. A decrease in between-cluster diversity has not been found in the core collection.  相似文献   

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