蓝尾石龙子精子的超微结构

蓝尾石龙子(Eumeces elegans)附睾以2．5％戊二醛和1％锇酸双重固定,按常规制作超薄切片,用H-600透射电镜研究观察精子的超微结构。精子由头部和尾组成,头部由顶体复合体和核组成,尾由颈段、中段、主段和末段组成。头部的顶体囊前部扁平,分为皮质和髓质,顶体下锥由类结晶状的顶体下物质组成,穿孔器顶端尖,、穿孔器基板塞子状,细胞核延长,核内小管缺,核伸展部前端具一电子透明区,核肩圆,核陷窝锥形。颈段具片层结构,近端中心粒和远端中心粒的长轴呈直角,9束外周致密纤维与远端中心粒相应的9束三联微管相联,向后与轴丝相应的9束双联微管相联,中央纤维与2个中央单微管相联。中段短,含有线状嵴的柱状线粒体,由连续的规则小卵状或小梯形致密体组成线粒体间的环状结构,纤维鞘伸入中段,终环紧贴于细胞膜的内表面。线粒体与环状结构的模式为：rs1／mi1,rs2／mi2,rs3／mi3,rs4／mi4,横切面上每圈线粒体数目为10个。主段前面部分具薄的细胞质颗粒区。纤维3和8至主段前端消失。轴丝复合体呈“9 2”型。蓝尾石龙子精子超微结构与已描述的石龙子科种类比较发现,与蜓蜥群和胎生群的石龙子相似;但没有发现石龙子科精子的独征。     

Principle of formation of biocenoses resistant to arising of the aggressive biotypes of insects

The results of computing the structure of the resistant and susceptible stands bear evidence that in a resistant one, about 20% trees have low resistance and compose a limited trophical niche of the pest. The checking up of this suggestion conducted in a region with different ecological conditions (the central part of Ukraine), confirms it. Hence, a resistant stand must consist of a definite level of the resistant pine groups rather than exclusively resistant ones even at polygenic control the resistance. We have conducted the systematization of information from observations as to the damage scale of the pine and a number of cultured plant species by specialized pest insects. The aim of this systematization is the checking up of the regularity of the structure of resistant stands of the pine and cultured plants that are damage‐resistant. The analysis of the study's results bears evidence of the presence of the determined regularity in the structure of resistant biocenoses independent of species or varieties of the plants and also the specialized pests.     

Characterization of the translocon of the outer envelope of chloroplasts

The protein translocon of the outer envelope of chloroplasts (Toc) consists of the core subunits Toc159, Toc75, and Toc34. To investigate the molecular structure, the core complex was purified. This core complex has an apparent molecular mass of approximately 500 kD and a molecular stoichiometry of 1:4:4-5 between Toc159, Toc75, and Toc34. The isolated translocon recognizes both transit sequences and precursor proteins in a GTP-dependent manner, suggesting its functional integrity. The complex is embedded by the lipids phosphatidylcholine and digalactosyldiacylglyceride. Two-dimensional structural analysis by EM revealed roughly circular particles consistent with the formation of a stable core complex. The particles show a diameter of approximately 130 A with a solid ring and a less dense interior structure. A three-dimensional map obtained by random conical tilt reconstruction of electron micrographs suggests that a "finger"-like central region separates four curved translocation channels within one complex.     

Behavioural mode of action of deet: inhibition of lactic acid attraction

Using the mosquito Aedes aegypti in a novel olfactometer that measures movement towards and away from a stimulus, we could not confirm that 'deet' is a repellent of mosquitoes. In the absence of a host, deet was an attractant and in the presence of a host, it was an inhibitor of attraction. This inhibition occurred in the gaseous phase and was therefore not the result of the physical properties of deet. We determined that L-lactic acid, a component of human sweat that is an attractant to mosquitoes, is the target of this inhibition, implying that lactic acid may be a bottleneck in the behavioural cascade preceding blood-sucking.     

Genetic analysis of inbreeding of two strains of the parasitic nematode Haemonchus contortus

Haemonchus contortus is a sheep parasitic nematode that causes severe economic losses. Previous studies have indicated a high degree of genetic heterogeneity, which is hardly affected by selection for drug resistance. As a tool for the analysis of the population dynamics of H. contortus and its response to drug resistance, we designed a strategy to study the inbreeding of a benzimidazole-sensitive and a benzimidazole-resistant strain. After 15 generations, a theoretical inbreeding coefficient of 0.87 was achieved. The different stages of inbreeding were analysed using restriction fragment polymorphism, microsatellite variability and amplified fragment length polymorphism. Model-based clustering of the amplified fragment length polymorphism genotypes showed that the allele frequencies of the benzimidazole-resistant strain were stable during the last eight generations. In the sensitive strain a gradual shift of allele frequencies was observed, which led to a temporary increase of the genetic diversity around the eight generations.     

Principles of viable preservation of parasitic Protozoa

Viable preservation is fundamentally different from serial passage as a way of maintaining Protozoa in the laboratory. In serial passage there is continuous selection of a reproducing population so that biological characteristics deviate from those representative of the original population towards those of a population adapted to the special conditions of the passage. Viable preservation arrests reproduction and so, this selection. Viably preserved material, therefore, deserves to be defined by a special term, ‘stabilate’, a stabilate being defined as a population of organisms viably preserved on a unique occasion. Materials maintained by serial passage are appropriately called ‘strains’.     

Discounting of sequences of delayed rewards of different amounts

The main purpose of this study was to determine whether the magnitude effect is present in cases where delayed sequences of rewards are discounted. The magnitude effect refers to the inverse relationship between the amount of a reward and the steepness of temporal discounting. This study was conducted with a computer program to estimate the indifference points, which served as indicators of the present subjective value of delayed sequences of small and large rewards. In the indifference point the subjective value of a single, immediate reward was equal to the subjective value of the delayed sequence (or to the value of a single delayed reward). As a control condition, we added an experimental task involving choices between single immediate and single delayed rewards. The experiment showed that the sequences of large rewards are discounted less steeply than are the sequences of small rewards. This finding suggests that the magnitude effect is present within the delayed sequences of rewards. In addition, when outcomes are relatively large, the results suggest that a single reward is discounted less steeply than the sequence of a total nominal value equal to this single reward. However, for relatively small rewards, the difference is not statistically significant. The less steep discounting of sequences of large rewards may explain the reward-bundling effect, which refers to less steep discounting of longer sequences than of shorter ones: longer sequences usually have greater overall nominal value. The present study was conducted on hypothetical rewards, and the results should be validated using real rewards.     

Experimental test of the influence of the size of shoals and density of fish on parasite infections

There is an increasing interest in the relationship between adult coral reef fishes and their parasites; however, there is almost no information concerning post larvae (i.e. newly recruited) fish and their parasites. Newly recruited and juvenile fish are highly sensitive to their environment and they have a very low survival rate. Fish grouping behavior has been studied in several ways and many studies have shown that increasing group size might be a way to share a cost linked to parasitism, via a dilution effect. To my knowledge, this hypothesis has never been tested for juveniles of fish. The potential influence of school size and density of a juvenile coral reef fish, Haemulon flavolineatum (Haemulidae), on the success of a monogenean fish parasite, Haliotrema sp., was studied. First, the fish acquired their monogeneans when they were more than 40 mm long, size corresponding also to a change in their foraging behavior. Second, there was a positive effect of fish density on the success of the establishment of the parasite on the host population. Finally, although the parasite success was not directly related to fish group size, the parasite abundance was higher for intermediate shoal size. These results are discussed in terms of the consequence parasitism may have on a fish's shoaling and to a larger extent on the fish population.     

Effect of the canopy complexity of trees on the rate of predation of insects

The effect of the complexity of tree canopies on the effectiveness of biological control of tree‐dwelling insect herbivores by predators has been neglected. A complex canopy provides a greater variety of resources than a simple canopy, which may result in an increase in the abundance of both herbivores and predators in complex canopies and a higher predation rate. On the other hand, it may be more difficult to locate prey in trees with a complex canopy, which may lower the predation rate. The main aim of this study is to determine the relationship between predation rate and canopy complexity. We have used a system consisting of lime trees, larvae of blowflies as prey and naturally occurring predators (mainly birds and ants). The complexity of the canopy of 12 of the lime trees was reduced by pruning, and the predation rate was determined by recording the fate of prey pinned on each of the trees for 30 min several times during the course of a year. The predation rate was negatively associated with canopy complexity. We compare these results with those reported in the literature and contrary to the widely held view conclude that a negative relationship between predation rate and canopy complexity is a common phenomenon and can be expected to be reported in studies not only on ambush but also on predators that actively search for prey.     

Equilibrium Distributions of Populations of Biological Species on Networks of Social Sites

ABSTRACT

We investigate the problem of how a population of biological species would distribute over a given network of social sites so that their social contacts through the connected sites can be maximized (or minimized). This problem has applications in modelling the behaviours of social (or solitary) species such as the development of social groups in human society and the spread of solitary animals in distant habitats. We show that this problem can be formulated as an evolutionary game, with the equilibrium state of the game corresponding to a strategy for choosing the residing sites, each with a certain probability, or equivalently, to a distribution of the population on these sites. The game has a symmetric payoff matrix, and can therefore be analyzed via the solution of a corresponding quadratic programme: An equilibrium strategy of the game is a KKT point of the quadratic programme, which may be a local maximizer, local minimizer, or saddle point, but it is evolutionarily stable if and only if it is a strict local maximizer. In general, with a goal to maximize the social contacts, the species tend to spread on network sites where there are dense connections such as a complete subnetwork or in other words, a network clique. We show that at equilibrium, the population may or may not distribute on a network clique, but the stability of the equilibrium state does depend on the structure of the selected subnetwork. In particular, we show that the distribution of the population on a maximal network clique is evolutionarily stable unless the clique is ‘attached’ to another clique of the same or larger size, when the population may be able to switch or expand to the neighbouring clique to increase or at least maintain its total amount of contacts. However, the distribution of the population on a non-clique subnetwork is always evolutionarily unstable or weakly evolutionarily stable at the very best, for the population can always move away from its current distribution without decreasing its total amount of contacts. We conclude that the strategies to spread on maximal network cliques are not only equilibrium strategies but also evolutionarily more stable than those on non-clique subnetworks, thus theoretically reaffirming the evolutionary advantages of joining social cliques in social networks for social species.     

Impact of taxon sampling on the estimation of rates of evolution at sites

The function of individual sites within a protein influences their rate of accepted point mutation. During the computation of phylogenetic likelihoods, rate heterogeneity can be modeled on a site-per-site basis with relative rates drawn from a discretized Gamma-distribution. Site-rate estimates (e.g., the rate of highest posterior probability given the data at a site) can then be used as a measure of evolutionary constraints imposed by function. However, if the sequence availability is limited, the estimation of rates is subject to sampling error. This article presents a simulation study that evaluates the robustness of evolutionary site-rate estimates for both small and phylogenetically unbalanced samples. The sampling error on rate estimates was first evaluated for alignments that included 5-45 sequences, sampled by jackknifing, from a master alignment containing 968 sequences. We observed that the potentially enhanced resolution among site rates due to the inclusion of a larger number of rate categories is negated by the difficulty in correctly estimating intermediate rates. This effect is marked for data sets with less than 30 sequences. Although the computation of likelihood theoretically accounts for phylogenetic distances through branch lengths, the introduction of a single long-branch outlier sequence had a significant negative effect on site-rate estimates. Finally, the presence of a shift in rates of evolution between related lineages can be diagnostic of a gain/loss of function within a protein family. Our analyses indicate that detecting these rate shifts is a harder problem than estimating rates. This is so, partially, because the difference in rates depends on two rate estimates, each with an intrinsic uncertainty. The performances of four methods to detect these site-rate shifts are evaluated and compared. Guidelines are suggested for preparing data sets minimally influenced by error introduced by sequence sampling.     

Effect of rootstock on photoperiodic control of elongation growth in grafted ecotypes of Salix

Scions of a southern (59° 40'N Lat.) and a northern (69° 39'N Lat.) ecotype of Salix pentandra L. were grafted on clonal rootstocks of the same ecotypes. Effects of photoperiod on elongation growth of the 4 combinations (south/south, south/north, north/south and north/north) were studied in a phytotron at 18° and 15°C. The photoperiodic response was primarily dependent on the ecotype of the scion, but this response was significantly modified by the rootstock. Cessation of apical growth was advanced by a northern clone and delayed by a southern clone as a rootstock. The results indicate that the critical photoperiod for cessation of apical growth could be slightly decreased by a northern and increased by a southern rootstock.     

Spatial division of labour of Schoenoplectus americanus

If connected ramets are growing in heterogeneous environments, Division of Labour (DoL) among ramets potentially will result in more efficient sharing of resources and an overall benefit to the plants. As a result of DoL, connected ramets growing in a heterogeneous environment might achieve more biomass than ramets growing in a homogeneous environment. DoL has been demonstrated to occur in a few clonal plant species, although most studies simply focussed on biomass allocation, not on actual resource capturing such as water and nutrient consumption. The model system for our study is one in which two connected ramet groups of Schoenoplectus americanus were placed into contrasting environments. In one treatment, the connected ramets grew in heterogeneous environments and in the other treatment, the connected ramets grew in the same (i.e. homogeneous) environment. We manipulated two variables (light and salinity) in the experiment. We hypothesized that ramets growing in a shaded and fresh water condition in a heterogeneous environment would use more water than ramets growing in a similar condition but in a homogeneous environment. We further hypothesized that ramets growing in a light and saline condition in a heterogeneous environment would assimilate less water than ramets growing in a similar condition but in a homogeneous environment. These hypotheses are based on the assumption that ramets in a heterogeneous environment would translocate water from ramets growing in a shaded and fresh water condition to ramets growing in a light and saline water condition. We also hypothesized that ramets growing in heterogeneous environments achieve larger biomass than ramets in homogeneous environments. Ramets grown in light and saline conditions in heterogeneous environments allocated more biomass to aboveground parts, had taller shoots, larger Specific Green (leaf) Area and consumed less water than ramets grown in similar conditions but in a homogeneous environment. Results confirm the hypothesis that connected ramets in heterogeneous environments are specialised to capture locally abundant resources and share these with connected ramets growing in other habitats. The result of DoL is that the entire connected ramet system benefits and achieves higher biomass.     

1590名农村中老年人生存质量调查分析(英文)

目的:采用SF-36量表中文版评价农村中老年人生存质量,并为提高农村中老年人的生存质量和健康水平提供科学依据和建议。方法:采用随机抽样的方法,采用面对面访谈的形式,记分方法参照国际生存质量评价计划(IQOLA)的制定标准,评价其生理和心理健康状况。结果:1590名农村中老年人男性生存质量得分高于女性。经济水平对农村中老年人的生理健康的影响大于对其心理健康的影响。配偶健在的农村中老年人的各维度得分均高于无配偶者。农村中老年人的各维度得分随教育水平的升高呈升高趋势。结论:农村中老年人的生存质量与年龄成负相关,同时也受文化程度和经济水平等多个因素的影响。因而,对农村中老年人这一弱势群体应该给予更多关注。     

The effects of glutamine of the maintenance of embryogenic cultures of Cryptomeria japonica

Summary Embryogenic tissues of sugi (Cryptomeria japonica) were induced on a modified Campbell and Durzan (CD) medium containing 1 μM 2,4-dichlorophenoxyacetic acid (2,4-D) and 600 mg l⁻¹ glutamine, and subcultured in the medium of the same composition for over 1 yr. This resulted in a mixed culture of embryogenic and non-embryogenic cells. When embryogenic cells were isolated and cultured independently, their capacity to form embryogenic aggregates was lost. Thus, the non-embryogenic cells present within a mixed culture system were essential to the formation of embryogenic aggregates. When embryogenic tissues were isolated and cultured independently on a high glutamine-containing (2400 mg l⁻¹) medium, dry weights and endogenous levels of glutamine increased, and the tissue could generate a large number of embryogenic aggregates. Amino acid analysis of embryogenic and non-embryogenic cells from the maintenance culture indicated a higher level of glutamine was present in the latter. The high endogenous level of glutamine in the non-embryogenic portion of mixed cell masses may be the supplier of glutamine for maintaining the embryogenic property of the tissues.     

Cause of Senescence of Nine Sorts of Flowers

The levels of endogenous phytohormones and respiratory rate in nine sorts of flowers such as Cymbidium faberi Rolfe, Nopalxochia ackermannii Kunth and others were investigated both at full bloom and senescence and meanwhile the effect of exogenous phytohormones on prolonging the blossoms and promoting ethylene production were tested. There is a high content of endogenous ethylene in all the long-lived flowere, about 3–16 folds higer than the short-lived ones. There is a high level of ABA at full blooming flowers of short-lived flowers, in which there is no or only some cytokinins in it, but the ratio of CTK (6BA+zeatin)/ABA is smaller(l.7). The endogenous ABA reached a much higher level at senescence in all nine sorts of flowers, so it is reasonable to consider that it is ABA which plays an important role of regulation in controlling flower's senescence. There is a much higher level of GA3 and zeatin in the long-lived flowers which is not demonstrated in the shortlived ones. The respiratory rate is one of the factors controtling the longevity of flowers, but it does not play a decided role. Application of 6BA and zeatin prolongs distinctly orchid’s longevity, however exogenous IAA through the promotive action on ethylene production, evidently extends the longevity of the flowers of the Nopalxochia ackermannii Kunth.     

Asymptotic rates of growth of the extinction probability of a mutant gene

We prove that a result of Haldane (1927) that relates the asymptotic behaviour of the extinction probability of a slightly supercritical Poisson branching process to the mean number of offspring is true for a general Bienaymé-Galton-Watson branching process, provided that the second derivatives of the probability-generating functions converge uniformly to a non-zero limit. We show also by examples that such a result is true more widely than our proof suggests and exhibit some counter-examples.Research supported by NSERC     

Biosynthesis of pulmonary glycoconjugates. Mechanism of glucosylation of protein and lipid acceptors

In sheep lung microsomes, we have shown that glucosyl-transferases catalize the transfer of glucose from UDP-glucose into four different acceptors. The glucosylated products obtained are as follows: - a glucosyl-phosphoryl-polyprenol (product A) extractable by chloroform/methanol (2:1 by volume). - a product B extractable by chloroform/methanol/water (10:10:3 by volume). The product B was a mixture of five glycolipids, one of them having a chromatographic behaviour similar to the behaviour of a tetrahexosylceramide (asia-lo-GM1). - a product C insoluble in water and organic solvents which has been demonstrated to be a glycoproteinic compound. The molecular weight of this product C was 160 000 as estimated by gel-filtration. The carbohydrate moiety is composed of small oligosaccharides which are found to be attached by O-glycosidic bond to the protein chain. This linkage is not a collagen-like bond.     

The restoration of anatomic form of atrophied alveolar processes of jaws with the help of bioimplant lioplast

The purpose of the present research was: 1. To investigate the opportunity of application of allogen osteoplastic materials such as Lioplast, received in Samara Tissue Bank of Samara State Medical University. 2. To work out a new technique of producing lyophilized allogen osteoplastic materials, such as Lioplast, with application of an ultrasonic method of clearing. 3. The development of various techniques of operative intervention on jaws for increase in volume of atrophied, as a result of secondary adentia, alveolar shoot. 4. The application of spongy allogen osteoplastic material as a skeleton for filling in surgical operations on jaws. 5. The demonstration of the Technique of a bone-periostic Lioplast 'sandwich' for formation of an alveolar shoot.