共查询到20条相似文献,搜索用时 31 毫秒
1.
2.
横断山区的蝶类561种,隶属于12科,208属.在12科中,种类最多的是蛱蝶科148种,其次是眼蝶科117种,灰蝶科65种,凤蝶科63种,粉蝶科60种,弄蝶科60种,蚬蝶科18种,绢蝶科12种,斑蝶科9种,环蝶科6种,喙蝶科2种,珍蝶科1种.分布于横断山区的珍稀蝴蝶有44种,其中国家Ⅰ级保护的1种,Ⅱ级保护的3种. 相似文献
3.
西双版纳热带雨林蚁科昆虫区系分析 总被引:9,自引:1,他引:8
在西双版纳热带雨林已鉴定蚊科昆虫9亚科76属267种。西双版纳地区的蚂蚁区系以热带至亚热带分布的东洋界成分最为丰富。在属级水平上,与马来西亚界关系最为密切。与澳洲界关系较密切;与非洲界和马拉加西界的关系知中。与新北界,新热带界和古北界的关系最为疏远。可见西双版纳的蚂蚁区系具有典型的热带亚洲起源特征,同时与澳洲和非洲的热带区系有一定的渊源关系。 相似文献
4.
Robert M. Levin Benjamin Weiss 《Biochimica et Biophysica Acta (BBA)/General Subjects》1978,540(2):197-204
Trifluoperazine inhibits the activation of phosphodiesterase by binding to the calcium-dependent activator. To determine further the specificity by which trifluoperazine binds to activator, we compared the binding of trifluoperazine to activator prepared from several species and tissues and to a number of other calcium-binding proteins devoid of activator activity.Trifluoperazine binds to activator prepared from human, bovine, rat and rabbit brain and from chick embryo fibroblasts. In each case, the binding of trifluoperazine to activator was qualitatively similar and related quantitatively to the ability of the preparation to activate phosphodiesterase.Of the other calcium-binding proteins examined, namely, troponin-C, S-100 protein, phospholipase A, phospholipase B and myosin light chain, only troponin-C displayed any significant calcium-specific binding of trifluoperazine. The binding to troponin-C, however, appeared to be different from the binding to activator; whereas the binding of trifluoperazine to actovator showed no cooperativity, the binding to troponin-C showed positive cooperatively.These results and earlier data showing that trifluoperazine fails to bind to a variety of other proteins, indicate that the binding of trifluoperazine to the calcium-dependent activator of phosphodiesterase is selective and suggest that this binding may explain some of the biochemical and pharmacological actions of this antipsychotic agent. 相似文献
5.
Localization of Escherichia coli RNA polymerase binding sites on bacteriophage S13 and 0X174 DNAs by electron microscopy.
下载免费PDF全文
![点击此处可从《Journal of virology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Complexes between Escherichia coli RNA polymerase and bacteriophage S13 and phage phiX174 replicative form III DNAs have been shown to form at specific locations on the phage genomes. The major locations on S13 have been mapped at 8 to 10 and 92 to 96% of the genome length, starting from the unique Pst I cleavage site. The locations correspond to the beginnings of genes D and B, respectively. Four minor locations map at 18 to 22, 28 to 32, 50 to 56, and 70 to 74% of the genome. The 70 to 74% site corresponds to the beginning of the A gene. The major locations on phiX174 are at 8 to 10, 50 to 54, and 92 to 94% of the genome. The 50 to 54% site is at the start of the H gene and has an equivalent minor site on S13, but it is not a promoter site. Three minor sites on phiX174, at 20 to 24, 26 to 32, and 68 to 74% of the genome, correspond to sites on S13. The data confirm the locations of sites identified by restriction fragment binding experiments (E. Rassart and J. H. Spencer, J. Virol. 27:677--687, 1978) and the assignment of putative promoters at the start of genes A, B and D. 相似文献
6.
Mauro C Vito P Mellone S Pacifico F Chariot A Formisano S Leonardi A 《Biochemical and biophysical research communications》2003,309(1):84-90
Nuclear factor kappaB (NF-kappaB) plays a pivotal role in numerous cellular processes, including stress response, inflammation, and protection from apoptosis. Therefore, the activity of NF-kappaB needs to be tightly regulated. We have previously identified a novel gene, named CIKS (connection to IkappaB-kinase and SAPK), able to bind the regulatory sub-unit NEMO/IKKgamma and to activate NF-kappaB. Here, we demonstrate that CIKS forms homo-oligomers, interacts with NEMO/IKKgamma, and is recruited to the IKK-complex upon cell stimulation. In addition, we identified the regions of CIKS responsible for these functions. We found that the ability of CIKS to oligomerize, and to be recruited to the IKK-complex is not sufficient to activate the NF-kappaB. In fact, a deletion mutant of CIKS able to oligomerize, to interact with NEMO/IKKgamma, and to be recruited to the IKK-complex does not activate NF-kappaB, suggesting that CIKS needs a second level of regulation to efficiently activate NF-kappaB. 相似文献
7.
V Krcméry L Langsádl M Antal A Seckárová 《Journal of hygiene, epidemiology, microbiology, and immunology》1985,29(2):141-146
Three strains belonging to gramnegative non-fermenting rods, i.e. a Pseudomonas maltophilia strain and two strains of Acinetobacter, were tested, as representatives of different types of nosocomial strains, for transferability of their multiple drug resistance. As all of them posed difficulties in demonstrating the transferability of their resistance by conventional methods, a three-step procedure was developed that includes a transfer to rifampicin-resistant P. aeruginosa recipients, then to susceptible P. aeruginosa intermediate strains, and, finally, from these strains to rifampicin-resistant Enterobacteriaceae. In three strains studied three genetically different types of R plasmids have been demonstrated. P. maltophilia transferred Amikacin resistance, as well as resistance to other antibiotics, to P. aeruginosa and then to Enterobacteria. In contrast, an Amikacin-resistant Acinetobacter with quite identical multiple drug resistance spectrum transferred its resistance to P. aeruginosa only, but not to Enterobacteria. Finally, another Acinetobacter strain, resistant to Gentamicin but susceptible to Amikacin transferred this resistance directly to Enterobacteria (and, separately, to P. aeruginosa, too). All three strains transferred Cefamandole resistance together with other resistances. Non-fermenting rods, thus, might be a source of transmissible resistance to reserve antibiotics as Amikacin, and advanced-type Cephalosporins. 相似文献
8.
Daniel T. Blumstein 《Ethology : formerly Zeitschrift fur Tierpsychologie》1998,104(6):501-516
Although a variety of behaviors expose animals to some risk of predation, there is no accepted way to compare their relative risk. For animals that retreat to refugia when alarmed by predators, the proportion of time devoted to each out-of-refuge behavior multiplied by the total time required to return to a refuge can be used to compare a behavior's relative predation risk. Total time to return to a refuge is a function of both response time - the time required to respond to an increased risk of predation — and travel time — the time required to flee to a refuge once alarmed. Quantifying these components can illustrate how animals minimize exposure to predators. Golden marmots (Marmota caudata aurea) were a refuging prey species used to examine the utility of this measure and to understand how marmots minimized their risk of exposure to predation. Golden marmots devoted different amounts of time to looking, foraging, self-grooming, and playing. To estimate the behavior-specific time required to return to refugia, the location of different activities was noted and a behavior-specific travel time was calculated. Alarm calls were played back to marmots engaged in different behaviors to determine, in a standardized manner, if there were behavior-specific response times. Marmots appeared to minimize their predation risk by performing most behaviors close to refugia. Results suggest that foraging was the riskiest behavior, largely because marmots foraged far from refugia and spent about 30% of their time foraging. While sample sizes were small, results also suggested that play, a rare adult behavior, exposed animals to predation because of a relatively long response time. 相似文献
9.
Surface topology of the Escherichia coli K-12 ferric enterobactin receptor. 总被引:28,自引:18,他引:10
下载免费PDF全文
![点击此处可从《Journal of bacteriology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Monoclonal antibodies (MAb) were raised to the Escherichia coli K-12 ferric enterobactin receptor, FepA, and used to identify regions of the polypeptide that are involved in interaction with its ligands ferric enterobactin and colicins B and D. A total of 11 distinct FepA epitopes were identified. The locations of these epitopes within the primary sequence of FepA were mapped by screening MAb against a library of FepA::PhoA fusion proteins, a FepA deletion mutant, and proteolytically modified FepA. These experiments localized the 11 epitopes to seven different regions within the FepA polypeptide, including residues 2 to 24, 27 to 37, 100 to 178, 204 to 227, 258 to 290, 290 to 339, and 382 to 400 of the mature protein. Cell surface-exposed epitopes of FepA were identified and discriminated by cytofluorimetry and by the ability of MAb that recognize them to block the interaction of FepA with its ligands. Seven surface epitopes were defined, including one each in regions 27 to 37, 204 to 227, and 258 to 290 and two each in regions 290 to 339 and 382 to 400. One of these, within region 290 to 339, was recognized by MAb in bacteria containing intact (rfa+) lipopolysaccharide (LPS); all other surface epitopes were susceptible to MAb binding only in a strain containing a truncated (rfaD) LPS core, suggesting that they are physically shielded by E. coli K-12 LPS core sugars. Antibody binding to FepA surface epitopes within region 290 to 339 or 382 to 400 inhibited killing by colicin B or D and the uptake of ferric enterobactin. In addition to the FepA-specific MAb, antibodies that recognized other outer membrane components, including Cir, OmpA, TonA, and LPS, were identified. Immunochemical and biochemical characterization of the surface structures of FepA and analysis of its hydrophobicity and amphilicity were used to generate a model of the ferric enterobactin receptor's transmembrane strands, surface peptides, and ligand-binding domains. 相似文献
10.
Specificity of the binding of trifluoperazine to the calcium-dependent activator of phosphodiesterase and to a series of other calcium-binding proteins. 总被引:15,自引:0,他引:15
Trifluoperazine inhibits the activation of phosphodiesterase by binding to the calcium-dependent activator. To determine further the specificity by which trifluoperazine binds to activator, we compared the binding of trifluoperazine to activator prepared from several species and tissues and to a number of other calcium-binding proteins devoid of activator activity. Trifluoperazine binds to activator prepared from human, bovine, rat and rabbit brain and from chick embryo fibroblasts. In each case, the binding of trifluoperazine to activator was qualitatively similar and related quantitatively to the ability of the preparation to activate phosphodiesterase. Of the other calcium-binding proteins examined, namely, troponin-C, S-100 protein, phospholipase A, phospholipase B and myosin light chain, only troponin-C displayed any significant calcium-specific binding of trifluoperazine. The binding to troponin-C, however, appeared to be different from the binding to activator; whereas the binding of trifluoperazine to actovator showed no cooperativity, the binding to troponin-C showed positive cooperatively. These results and earlier data showing that trifluoperazine fails to bind to a variety of other proteins, indicate that the binding of trifluoperazine to the calcium-dependent activator of phosphodiesterase is selective and suggest that this binding may explain some of the biochemical and pharmacological actions of this antipsychotic agent. 相似文献
11.
《Applied animal behaviour science》2007,102(3-4):246-261
Cognitive mechanisms are an important part of the organization of the behavior systems of animals. In the wild, animals regularly face problems that they must overcome in order to survive and thrive. Solving such problems often requires animals to process, store, retrieve, and act upon information from the environment—in other words, to use their cognitive skills. For example, animals may have to use navigational, tool-making or cooperative social skills in order to procure their food. However, many enrichment programs for captive animals do not include the integration of these types of cognitive challenges. Thus, foraging enrichments typically are designed to facilitate the physical expression of feeding behaviors such as food-searching and food consumption, but not to facilitate complex problem solving behaviors related to food acquisition. Challenging animals by presenting them with problems is almost certainly a source of frustration and stress. However, we suggest here that this is an important, and even necessary, feature of an enrichment program, as long as animals also possess the skills and resources to effectively solve the problems with which they are presented. We discuss this with reference to theories about the emotional consequences of coping with challenge, the association between lack of challenge and the development of abnormal behavior, and the benefits of stress (arousal) in facilitating learning and memory of relevant skills. Much remains to be done to provide empirical support for these theories. However, they do point the way to a practical approach to improving animal welfare—to design enrichments to facilitate the cognitive mechanisms which underlie the performance of complex behaviors that cannot be performed due to the restrictions inherent to the captive environment. 相似文献
12.
Pasquali R 《Annals of the New York Academy of Sciences》2012,1264(1):20-35
Obesity, particularly the abdominal phenotype, has been ascribed to an individual maladaptation to chronic environmental stress exposure mediated by a dysregulation of related neuroendocrine axes. Alterations in the control and action of the hypothalamic-pituitary-adrenal axis play a major role in this context, with the participation of the sympathetic nervous system. The ability to adapt to chronic stress may differ according to sex, with specific pathophysiological events leading to the development of stress-related chronic diseases. This seems to be influenced by the regulatory effects of sex hormones, particularly androgens. Stress may also disrupt the control of feeding, with some differences according to sex. Finally, the amount of experimental data in both animals and humans may help to shed more light on specific phenotypes of obesity, strictly related to the chronic exposure to stress. This challenge may potentially imply a different pathophysiological perspective and, possibly, a specific treatment. 相似文献
13.
Kaakeh W 《Journal of economic entomology》2005,98(6):2137-2142
Forty-six local and imported wood were tested for resistance to feeding damage by the termite Anacanthotermes ochraceus (Burmeister), the most dominant species in the United Arab Emirates and the Arab Gulf region. Wood was used for construction, wall paneling, and furniture. Wood was evaluated in a 4-wk forced feeding bioassay. Each wood block was graded by the amount of termite damage by using a damage rating index (DRI) of 0 to 5 and wood rating index from very resistant to very susceptible wood. Local wood was mostly susceptible to feeding of termites; imported wood varied in resistance to feeding damage. Wood was placed in groups according to the percentages of weight loss (WL), termite survival (TS), and DRI. Wood was classified as very resistant (%WL from 0.0 to 0.3, %TS from 0.01 to 0.5, and DRI of 0.01), resistant (%WL from 1.1 to 4.9, %TS from 0.8 to 4.8, and DRI of 1.0), moderately resistant (%WL from 6.6 to 9.3, %TS from 6.3 to 8.3, and DRI of 2.0-2.3), slightly resistant (%WL from 10.1 to 19.9, %TS from 9.5 to 28.0, and DRI of 2.5-3.5), susceptible (%WL from 21.5 to 48.6, %TS from 37.3 to 64.8, and DRI of 4.0-4.3) and very susceptible (%WL from 50.0 to 59.8, %TS from 72.8 to 79.0, and DRI of 4.5-5.0). The characterization of the extracts of resistant wood may prove of economic value and lead to the development of new chemicals (repellents or antifeedants) for termite control. 相似文献
14.
Valladares F Hernández LG Dobarro I García-Pérez C Sanz R Pugnaire FI 《Annals of botany》2003,91(5):577-584
Different plant species and organs within a plant differ in their plastic response to light. These responses influence their performance and survival in relation to the light environment, which may range from full sunlight to deep shade. Plasticity, especially with regard to physiological features, is linked to a greater capacity to exploit high light and is usually low in shade-tolerant species. Among photosynthetic organs, green stems, which represent a large fraction of the total photosynthetic area of certain species, are hypothesized to be less capable of adjustment to light than leaves, because of biomechanical and hydraulic constraints. The response to light by leaves and stems of six species of leguminous, green-stemmed shrubs from dry and high-light environments was studied by growing seedlings in three light environments: deep shade, moderate shade and sun (3, 30 and 100 % of full sunlight, respectively). Survival in deep shade ranged from 2 % in Retama sphaerocarpa to 74 % in Ulex europaeus. Survival was maximal at moderate shade in all species, ranging from 80 to 98 %. The six species differed significantly in their ratio of leaf to total photosynthetic area, which influenced their light response. Survival in deep shade increased significantly with increasing ratio of leaf to total photosynthetic area, and decreased with increasing plasticity in net photosynthesis and dark respiration. Responses to light differed between stems and leaves within each species. Mean phenotypic plasticity for the variables leaf or stem specific mass, chlorophyll content, chlorophyll a/b ratio, and carotenoid to chlorophyll ratio of leaves, was inversely related to that of stems. Although mean plasticity of stems increased with the ratio of leaf to total photosynthetic area, the mean plasticity of leaves decreased. Shrubs with green stems and a low ratio of leaf to total photosynthetic area are expected to be restricted to well-lit habitats, at least during the seedling stage, owing to their inefficient light capture and the low plasticity of their stems. 相似文献
15.
Susceptibility of Coagulase-negative Staphylococci to Lysostaphin and Other Antibiotics 总被引:10,自引:2,他引:10
下载免费PDF全文
![点击此处可从《Applied microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
In general, coagulase-negative staphylococci were found to be relatively less susceptible to the lytic action of lysostaphin than coagulase-positive staphylococci. To achieve, arbitrarily, a lysis greater than 75%, it was necessary to use an increased concentration of enzyme or a longer incubation period than that usually required with coagulase-positive strains. For the most part, the cultures studied were sensitive to oxacillin, cloxacillin, dicloxacillin, nafcillin, ancillin, cephalothin, cephaloridine, fusidic acid, lincomycin, novobiocin, and neomycin [median minimal inhibitory concentrations (MIC) of 1.56 mug/ml or less]. Some degree of resistance (median MIC values of 12.5 mug/ml or greater) to benzylpenicillin, ampicillin, methicillin, tetracycline, chloretetracycline, erythromycin, ristocetin, and lysostaphin was found. Ten methicillin-resistant, coagulase-negative staphylococal strains were found to be cross-resistant to all nine of the penicillins tested, but much less resistant to the two cephalosporin analogues. In several instances, some of these strains seemed to be more sensitive to benzylpenicillin and to certain of the semisynthetic penicillins than to methicillin. Of the 18 antibiotics tested with the viable plate count method, the methicillin-resistant strains were found to be the most sensitive to lincomycin and novobiocin. 相似文献
16.
Marion Frank 《The Journal of general physiology》1973,61(5):588-618
Sensitivities to moderately intense stimuli representing four taste qualities to man were determined for 79 hamster chorda tympani fibers. Some fibers were very sensitive to sucrose, sodium chloride, or hydrochloric acid, but none were very sensitive to quinine. These sensitivities were not randomly distributed among fibers: the sucrose sensitivity was separated from and negatively correlated with the other sensitivities which were associated and positively correlated with each other. Moreover, there were a limited number of sensitivity patterns: (a) fibers responding best to sucrose responded second-best to salt, less to acid, not to quinine; (b) fibers responding best to salt either responded second-best to sucrose and not to acid or quinine; or second-best to acid, less to quinine, and not to sucrose; and (c) fibers responding best to acid responded second-best to salt, more to quinine, and less to sucrose than other fibers. Therefore, if four stimuli of different taste qualities are ordered from acceptable to unacceptable, neural response functions of most hamster chorda tympani taste fibers peak at one point. Sensitivities to nine other moderately intense stimuli which vary in quality to man were also determined for 46–49 of the fibers. Sensitivities to sweet stimuli were always associated with each other and separated from sensitivities to nonsweet stimuli. Sensitivities to nonsweet stimuli were all associated with each other; however, the strongest correlations were between sensitivities to stimuli of like quality, e.g., the three acids or the two sodium salts. 相似文献
17.
For restoration to be an effective strategy to reverse large‐scale habitat loss and land degradation, funding programs need policies that promote selection of and commitment to projects that can reasonably be expected to succeed. Programmatic project selection practices have received minimal formal evaluation, despite their importance. In this study, we considered the extent to which a program needs to consider both ecological and organizational factors during project selection in order to minimize the incidence of project failure. Our assessment of a long‐term program that funds ecological restoration efforts across Minnesota (U.S.A.), based on project records, manager surveys, and field surveys, yielded several broadly relevant insights. First, factors well understood to confer ecological resilience (level of landscape alteration and starting condition) were clearly associated with restoration outcomes, regardless of time‐since‐initiation of restoration. Second, restoration of low‐resilience ecosystems is typically a labor‐ and skill‐intensive enterprise for organizations that undertake them. Our analysis revealed four organizational limitations, in addition to insufficient funds, that hindered capacity to keep projects on‐track: lack of planning and goal‐setting, inadequate staffing, leadership change, and incomplete records. Third, to reduce risk, programs do not necessarily need to avoid challenging projects, but do need to consider whether organizations proposing restorations have adequate internal capacity to competently plan and to sustain actions for a duration sufficient to restore ecological resilience. If a restoration is degraded enough to require human intervention to recover, the outcome of a project is as likely to reflect its organizational reality as much as its ecological circumstances. 相似文献
18.
Karasik D 《Human genetics》2008,124(4):349-356
Increased life expectancy has led to an overall aging of the population and greater numbers of elderly people. Therefore,
the number of people with osteoporosis has increased substantially, accompanied with an epidemic of hip fractures. Osteoporosis
is an age-related systemic condition that naturally occurs, among mammals, only in humans. Osteoporosis is known to be highly
heritable. However, assuming a genetic determinant for this post-reproductive disease to be transmitted from one generation
to the next is counter-intuitive, based on the principles of human evolution, I will attempt to provide an explanation of
the phenomenon from the point of view of evolution, selection, and changed environment in humans, which contributed to human
longevity, while on other hand, contribute to diseases of civilization, including osteoporosis. There is a need to delve into
evolution of human species in search for adaptive patterns to a specific environment that humans are operating in the last
couple of millennia, to clarify whether “good” and “bad” genes exist, and how to find and correct them. The answer to the
above questions will help us to identify causes of the current epidemic of osteoporosis and to pin-point a tailored treatment. 相似文献
19.
Summary. Plants are able to synthesise all amino acids essential for human and animal nutrition. Because the concentrations of some
of these dietary constituents, especially methionine, lysine, and threonine, are often low in edible plant sources, research
is being performed to understand the physiological, biochemical, and molecular mechanisms that contribute to their transport,
synthesis and accumulation in plants. This knowledge can be used to develop strategies allowing a manipulation of crop plants,
eventually improving their nutritional quality.
This article is intended to serve two purposes. The first is to provide a brief review on the physiology of methionine synthesis
in higher plants. The second is to highlight some recent findings linked to the metabolism of methionine in plants due to
its regulatory influence on the aspartate pathway and its implication in plant growth. This information can be used to develop
strategies to improve methionine content of plants and to provide crops with a higher nutritional value.
Received January 28, 2000 Accepted March 3, 2000 相似文献