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1.
Theoreticians predict that animal 'personality' traits may be maladaptive if fixed throughout different contexts, so the present study aimed to test whether these traits are fixed or plastic. Rainbow trout (Onchorhyncus mykiss) were given emboldening or negative experiences in the forms of watching bold or shy individuals responding to novelty or winning or losing fights to examine whether prior experience affected boldness. Bold individuals that lost fights or watched shy demonstrators became more shy by increasing their latency to approach a novel object, whereas shy observers that watched bold demonstrators remained cautious and did not modify their responses to novelty. Shy winners became bolder and decreased their latency to approach a novel object, but shy losers also displayed this shift. In comparison, control groups showed no change in behaviour. Bold fishes given negative experiences reduced their boldness which may be an adaptive response; however, shy fishes may base their strategic decisions upon self-assessment of their relative competitive ability and increase their boldness in situations where getting to resources more quickly ensures they outcompete better competitors.  相似文献   

2.
Adhesion molecule signalling: not always a sticky business   总被引:1,自引:0,他引:1  
The signalling activity of cell adhesion molecules (CAMs) such as cadherins, immunoglobulin-like CAMs or integrins has long been considered to be a direct consequence of their adhesive properties. However, there are physiological and pathological processes that reduce or even abrogate the adhesive properties of CAMs, such as cleavage, conformational changes, mutations and shedding. In some cases these 'adhesion deficient' CAMs still retain signalling properties through their cytoplasmic domains and/or their mutated or truncated extracellular domains. The ability of CAMs to activate signal transduction cascades in the absence of cell adhesion significantly extends their range of biological activities.  相似文献   

3.
4种蜘蛛染色体研究初报   总被引:5,自引:0,他引:5  
王佑举  王秀珍 《蛛形学报》1993,2(2):110-113
以早期胚胎细胞为材料,经秋水仙素处理、低渗、固定,制片及染色,制备蜘蛛体细胞染色体标本,并用血细胞染色体制片观察验证,镜检表明,4科4种蜘蛛的体细胞染色体数为:中华涡蛛(Oatonooa sinensis)为17和18,居室拟壁钱(Oecobius cellarioum)为22和24;北国壁钱(Uroctea lesserti)为39和42:大腹圆蛛(Aranea Ventricosus)为49和52。计数结果分析,它们的性别决定染色体机制是:中华涡蛛为XO型,居室拟壁钱为X_1X_2O型,北国壁钱为X_1X_2X_3O型,大腹圆蛛为X_1X_2X_3O型。  相似文献   

4.
Nucleolipids are hybrid molecules composed of a nucleobase, a nucleoside, a nucleotide or an oligonucleotide (either DNA or RNA), and a lipophilic moiety, which might be either simply a single- or double-chained alkyl (or alkenyl) moiety or a carbocyclic hydrocarbon such as cholesterol, a vitamin, or a bile acid. This review covers all aspects of nucleolipids, namely their natural occurrence, their synthesis, their molecular recognition, as well as aggregation behavior, either in aqueous or non-aqueous solution. Potential future aspects of nucleolipids in material sciences and for the elucidation of biochemical reactions in living cells are discussed.  相似文献   

5.
6.
Opt-out policies are typically invoked to excuse students from activities to which they or their parents may have religious objections, such as reciting the Pledge of Allegiance, dissecting animals in a laboratory, or attending sex education classes. Occasionally, however, a school or school district allows students to opt out of academic topics, including, sometimes, evolution. Opt-out policies specifically including evolution are a big mistake—for the students who opt out, for their classmates whose studies are disrupted, and especially for their teachers, who cannot fulfill their duty to instruct their charges about biology without emphasizing evolution.  相似文献   

7.
The present study on maternal ‘imprinting’ in goats initially failed to replicate previous findings that mothers discriminate between their own and alien young, accepting their own kid and rejecting alien kids. Rather, 62% of the mothers accepted both their own and alien kid. This disparity was not due to breed differences, age, or behaviour of the aliens but to length of time the alien kids had been with their own mother. When behaviour was eliminated through anaesthesia or left intact, older aliens that had had no contact with their mother were accepted by other mothers, while those aliens with more than 8 h of contact with their own mothers were rejected (whether anaesthetized or not) by other mothers. Maternal ‘imprinting’ in goats may take longer than previously reported, and mothers may ‘label’ their kids and learn to recognize the labels.  相似文献   

8.
The Color of My Skin is an instrument developed to assess children's internalized idea (abstraction) of the color of their skin; their satisfaction with that color; the desire, if any, to change the color of their skin; and their affect regarding their skin color. The assessment is part of a questionnaire utilized in a 3-year longitudinal study that examines psychosocial development, physical health, and behavioral adjustment of Puerto Rican children (N = 257) reared in the Greater Boston area. The results demonstrate that children's internalized representation of their skin color is a construct that can be reliably and validly measured. The children's ratings of their skin color were not associated with their sex, school grade, ethnic identity, the child's or the parent's nativity, or the racial or ethnic compositions of 3 social contexts: their neighborhood, their classmates, and their closest friends. Puerto Rican children did not show a preference for light-colored skin. Moreover, there were no significant differences in self-esteem based on the child's self-reported skin color. The lack of association between self-esteem and skin color was interpreted in light of a developmental tendency prevalent in early to middle childhood to place a positive value on different aspects of one's self. Whereas almost all children (96%) reported being happy or very happy with their color, 16% of the children would like to change their skin color if they could (51% to a lighter and 46% to a darker color).  相似文献   

9.
Oxysterols are structurally identical to cholesterol, but with one or more additional oxygen containing functional groups (such as alcohol, carbonyl or epoxide groups). The wide array of oxysterols encountered in human health and disease vary in their origin (either enzymic or non-enzymic), and their putative effects and/or function(s). Some are thought to be damaging, whereas others may play important physiological roles, including in the regulation of cholesterol homeostasis. In this review, we will concentrate on the major cellular oxysterols. We summarise their location, generation, metabolism and elimination, as well as providing insights into the latest research into their regulatory roles in cholesterol homeostasis.  相似文献   

10.
E. LANG. 1996. Seventeen aerobic bacterial strains known to degrade one or more aromatic compounds were tested for their ability to utilize benzene, seven different methylated benzenes or other aromatic compounds as their sole source of carbon. The results are discussed with respect to the possibility of finding strains which degrade one or more of these compounds by the applied method of screening, and to their taxonomic status.  相似文献   

11.
UDP-glucose:glycoprotein glucosyltransferase 1 (UGT1) is a central quality control gatekeeper in the mammalian endoplasmic reticulum (ER). The reglucosylation of glycoproteins supports their rebinding to the carbohydrate-binding ER molecular chaperones calnexin and calreticulin. A cell-based reglucosylation assay was used to investigate the role of UGT1 in ER protein surveillance or the quality control process. UGT1 was found to modify wild-type proteins or proteins that are expected to eventually traffic out of the ER through the secretory pathway. Trapping of reglucosylated wild-type substrates in their monoglucosylated state delayed their secretion. Whereas terminally misfolded substrates or off-pathway proteins were most efficiently reglucosylated by UGT1, the trapping of these mutant substrates in their reglucosylated or monoglucosylated state did not delay their degradation by the ER-associated degradation pathway. This indicated that monoglucosylated mutant proteins were actively extracted from the calnexin/calreticulin binding-reglucosylation cycle for degradation. Therefore trapping proteins in their monoglucosylated state was sufficient to delay their exit to the Golgi but had no effect on their rate of degradation, suggesting that the degradation selection process progressed in a dominant manner that was independent of reglucosylation and the glucose-containing A-branch on the substrate glycans.  相似文献   

12.
唐家河自然保护区冬季独栖羚牛及其习性   总被引:17,自引:0,他引:17  
笔者于1987年冬季至1988年春季对唐家河自然保护区离群的独栖羚牛进行了考察研究,获得了数量、分布及冬季活动规律等资料,并在行为生态、越冬适应及死亡限制因素等方面作了较深入的研究。这些老、弱、病、残羚牛离群而独栖生活,也是羚牛个体发生的必然规律;它们日趋衰弱,濒于死亡的边缘也是必然趋势。  相似文献   

13.
The Color of My Skin is an instrument developed to assess children's internalized idea (abstraction) of the color of their skin; their satisfaction with that color; the desire, if any, to change the color of their skin; and their affect regarding their skin color. The assessment is part of a questionnaire utilized in a 3-year longitudinal study that examines psychosocial development, physical health, and behavioral adjustment of Puerto Rican children (N = 257) reared in the Greater Boston area. The results demonstrate that children's internalized representation of their skin color is a construct that can be reliably and validly measured. The children's ratings of their skin color were not associated with their sex, school grade, ethnic identity, the child's or the parent's nativity, or the racial or ethnic compositions of 3 social contexts: their neighborhood, their classmates, and their closest friends. Puerto Rican children did not show a preference for light-colored skin. Moreover, there were no significant differences in self-esteem based on the child's self-reported skin color. The lack of association between self-esteem and skin color was interpreted in light of a developmental tendency prevalent in early to middle childhood to place a positive value on different aspects of one's self. Whereas almost all children (96%) reported being happy or very happy with their color, 16% of the children would like to change their skin color if they could (51% to a lighter and 46% to a darker color).  相似文献   

14.
Molecular motors hijacking by intracellular pathogens   总被引:4,自引:1,他引:3  
Cargoes are transported intracellularly along cytoskeletal tracks composed of actin or tubulin. Their movement involves the action of molecular motor proteins that generate directed movement along microtubules or actin filaments. The three classes of molecular motors--kinesins, dyneins and myosins--are involved in a multiplicity of biological movements such as mitosis, positioning of organelles, intracellular transports and also vesicular sorting through membrane tubulation and fission and delivery to their target compartment. Intracellular pathogens use this molecular machinery to reach their site of replication, to leave their host or to control the dynamics of membrane exchanges with their replication compartment.  相似文献   

15.
Cervical cancer can be not only prevented, but also effectively treated. Decreased efficiency of biochemical, neurohormonal and/or immunological mechanisms leads to infectious states which, irrespective of their bacterial, viral or parasitic aetiology, are only the necessary, but not the sufficient causes of neogenesis. The cause of cancer is the natural and common phenomenon of the self-organization of systems, endangered by ending of their existence, into more efficient time-space structures at the expense of their surrounding. Infected cells or infectiously changed tissues in their final phase of existence are often recognized as a precancerous state, but their genome does not differ from other organism cells, and that is why the carcinogenesis can still be prevented by direct fighting of pathogenic microorganisms, and indirectly by strengthening the body by neurohormonal therapy or vaccine immunopotentialization. Primary prophylaxis of neoplasms requires that not only the dissipathogenic state of cells be prevented, but also their tissue surrounding be normalized to head off the risk of the self-organization of neoplastic forms of life, differing in their genetic identity from the surrounding cells. Lactovaginal immunopotentialization complements the conservative and operative methods of oncological treatment, as well as has prophylactic application in women with the history of miscarriages, premature deliveries, lack of or significantly shortened lactation, neurohormonal menstruating disorders, chronic and recurrent inflammations of the reproductive organs, long-term hormonal contraception and hormone replacement therapy during menopause, or only deficiency of Lactobacillus vaginalis, as indicators of risk of cervical cancer.  相似文献   

16.
In contrast to marine organisms whose offspring go through an extended planktonic stage, the young of others develop directly into benthic juveniles or into yolky nonfeeding larvae that spend only a few hours in the plankton before settling. Yet, paradoxically, many such species have geographic distributions that are comparable to those with a pelagic dispersal stage. This article reviews some of the ways in which these organisms can expand their distributions: drifting, rafting, hitchhiking, creeping, and hopping. Drifting applies to species in which larvae may be short-lived, but adults can detach or be detached from their benthic substratum and be passively carried to new areas, floating at the water's surface or below it. Many encrusting species and mobile species can spread by rafting, settling on natural or artificial floating substrata which are propelled by wind and currents to new regions. Hitchhiking applies to those attaching to vessels or being carried in ballast water of ships to a distant region in which their offspring can survive. Other marine species extend their distributions by hopping from one island of hard substratum or favorable sedimentary microhabitat to another, while creeping species extend their distributions along shores or shelves where habitats remain similar for long distances.  相似文献   

17.
Phenolamides constitute a diverse and quantitatively major group of secondary metabolites resulting from the conjugation of a phenolic moiety with polyamines or with deaminated aromatic aminoacids. This review summarizes their bioactivities and their reported roles in plant development, adaptation and defence compared to those of their polyamine precursors. The most conclusive recent developments point to their contribution to cell-wall reinforcement and to direct toxicity for predators and pathogens, either as built-in or inducible defence. Phenolamides were often considered as accumulated end-chain products. Recent data bring a light on their biosynthesis and suggests their possible contribution in the branching of the phenylpropanoid metabolism.  相似文献   

18.
In-depth interviews were conducted with married Asian women from Indian, Pakistani and Bangladeshi backgrounds, to investigate patterns of contraceptive use and influences on contraceptive decision making. The results show two distinctively different contraceptive 'lifecycles'. Non-professional women typically have little knowledge about contraception until after their marriage or first birth. Their patterns of contraceptive behaviour show low levels of contraceptive use until after their first birth, when condom use is most prevalent. Non-professional women are influenced by their extended family, religion and cultural expectations on their fertility and family planning decisions. Professional women show an entirely different pattern of contraceptive behaviour. They are more likely to have knowledge about contraception before marriage, use some method of contraception throughout their childbearing years (typically the pill) and cite personal, practical or economic considerations in their fertility decisions rather than religious, cultural or extended family influences.  相似文献   

19.
目的:探讨索拉非尼(Sorafenib)和阿霉素(adriamycin)联合用药对肝癌细胞株nepG2的作用及可能的机制。方法:以不同浓度索拉非尼和不同浓度阿霉素分别组成单药组和索拉非尼+阿霉素联合用药组作用于HepG2细胞,MTT法检测增殖抑制率、流式细胞仪分析细胞周期和凋亡率。结果:索拉非尼、阿霉素单药与联用均能抑制HepG2细胞增殖,呈剂量依赖效应,两药联用有协同效应(P〈0.01)。索拉非尼、阿霉素单药与联用均能诱导HepG2细胞凋亡,并以联合组更为明显,与对照组比较有显著的统计学意义(P〈0.01)。索拉非尼及阿霉素单药作用均可使细胞周期阻滞于G0-G1期,联合用药组G0/Gl期细胞比率低于索拉非尼及阿霉素单药组,S期细胞比率高于单药组;阿霉素能抑制HepG2细胞Survivin mRNA表达诱导细胞的凋亡。结论:索拉非尼与阿霉素联合作用于人肝癌HepG2细胞具有协同作用,其机制可能是通过多途径共同抑制HepG2细胞增殖及诱导细胞凋亡。  相似文献   

20.
The particulars regarding the amine precursor therapy for treatment of neuropsychiatric disorders and their neurochemical background are described historically. Furthermore, peculiar or artificial amino acids which are metabolized into the brain amine or their derivatives and promised their clinical application are also introduced. Special issue dedicated to Dr. Kinya Kuriyama.  相似文献   

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