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1.
There are several hypotheses as to the function of postcopulatory mate guarding. Control over the mate-guarding period by either sex could potentially influence relative reproductive success. Mate-guarding behaviour in Gryllodes sigillatus was studied under several conditions: 1. undisturbed pairs; 2. pairs with a single male intruder; 3. pairs exposed acoustically, visually and olfactorily to several other males; 4. pairs exposed freely to several other males; and 5. pairs exposed freely to several other females. The results provide support for the spermatophore retention and rival defence hypotheses. The efficacy of mate guarding was not compromised by the pair being in acoustic, visual and olfactory contact with several other males. Once pairs were exposed to free contact with several other males, the spermatophore retention time by the female declined significantly, indicating that the mate guarder's efficiency declines under competition from several rivals. In pairs exposed to contact with several females after mating, the mate-guarding period and spermatophore retention time declined as the mate guarder abandoned the mated female and pursued the other females. Termination of the effective mate-guarding period by either sex seems to be influenced by the number of other potential partners present.  相似文献   

2.
东北羊草群落种群生态位重叠关系研究   总被引:24,自引:2,他引:24  
丛沛桐  颜廷芬 《植物研究》1999,19(2):212-219
本文通过对东北羊草草原不同羊草群落内各种群间生态位重叠关系的研究,揭示出羊草群落各种群对不同环境资源的利用能力及对生态因子的适应能力和占空间的能力。  相似文献   

3.
NF-κB pathway has long been considered as one of the potent prototypical pro-inflammatory signaling pathway and its role in several aspects of human health has been established. Recent studies have suggested that NF-κB activation is the master key in early development and pathobiology of several Cancers. Curcumin is a polyphenolic phytochemical compound with several stablished anti-inflammatory properties and is known to exert its anti-inflammatory effects mostly by interrupting NF-κB signaling pathway at multiple stages. Here we tried to provide a summary of recent finding, focusing on introducing NF-κB signaling pathways and its potential mechanism involved in development of several types of Cancers.  相似文献   

4.
The condiment name “oregano” should be understood to refer, not to any one species but to a particular spice flavor, furnished by plants of several genera in different parts of the world. About one-half of the amount used in the United States comes chiefly from Mexico as dried leaves and flowers of Lippia graveolens; the rest from several species of Origanum in several European countries.  相似文献   

5.
Insect endogenous retroviruses (IERVs) are present in the genome of several species. Previous studies have shown a relationship between the envelope glycoproteins (Envs) and fusion proteins (FPs) of several baculoviruses. We used this sequence similarity to predict fusion domains in the Envs of IERVs. We suggest that FPs and Envs share several specific sequence and structural motifs with other RNA viruses in the viral transmembrane protein superfamily.  相似文献   

6.
The family Camelidae has been present in Eurasia since the latest Miocene, and several species are recognized, but their evolution is poorly known. The region of El Kowm, central Syria, includes several sites spanning the Early to Late Pleistocene and provides the only abundant fossil record of camelids in the Middle East. Our preliminary results show that several species are present over the sequence, revealing some surprising evolutionary trends.  相似文献   

7.
四川省山蚋亚属一新种记述(双翅目,蚋科)   总被引:1,自引:0,他引:1  
继作者于2005年首次发现并记述四川省山蚋亚属二新种之后,报道四川省山蚋亚属另1新种,Simulium (Montisimulium)jiajinshanense sp.nov.(夹金山山蚋).本新种与报告自中国的S.(M.)tibetense Deng et al.,1993(西藏山蚋)and S.(M.)moxiense Chen et al.,2005(磨西山蚋),阿塞拜疆的S.(M.)assadovi(Djafarav,1956),亚美尼亚的S.(M.)litshkense(Rubtsov,1947),哈萨克斯坦的S.(M.)quattuordecimfiatliatum(Rubtsov,1947)和塔吉克斯坦的S.(M.)quattuordecimfilum Rubtsov,1947相似,均具14条呼吸丝,但新种可依据食窦弓具中突,两性生殖器的特殊形态,茧简单和呼吸丝特殊分枝等综合特征和上述近缘种相区别.  相似文献   

8.
9.
The molecular biology of viruses can be effectively described by kinetic logic as several feedback loops are implicated in all viral cycles and as viral proteins generally display several functions. We applied this method to the study of the rhabdovirus cycle.Formally, the dynamics of the model are explored on the basis of a discrete caricature (kinetic logic), with special emphasis on the role of the constitutive feedback loops to determine the essential dynamical behaviour of the viral cycle. From a biological point of view, our model accounts for several stable regimes or attractors: healthy cells, acute infection and different kinds of persistent infections, a multistationarity in good agreement with the existence of several positive feedback loops in our system.  相似文献   

10.
Targeted therapies are a recent development in cancer treatment research. As these therapies can only be administered to patients with certain individual characteristics, it is a straightforward idea to investigate several of such therapies simultaneously in a given patient population in order to compare each targeted therapy with the current standard therapy. This raises the question how patients satisfying several characteristics should be handled. We consider in this paper several designs to allocate treatments in a random manner to these patients, such that the evaluation of each single targeted therapy can be based on a simple comparison of patients receiving the targeted therapies versus those receiving the standard therapy within a well defined subgroup of patients satisfying the corresponding characteristic. We show how one can ensure that patients with several characteristics can contribute simultaneously to the evaluation of several targeted therapies and that this is the key point for an efficient use of the patients available. We further discuss some ethical and practical issues in applying the new designs and outline strategies to evaluate the overall effect of all targeted therapies together.  相似文献   

11.
Glutamate-gated ion channels belong to a complex family of receptors containing several pharmacological subtypes. They are thought to be essential for the acquisition of associative memory and for activity-dependent synaptogenesis, and have been implicated in several central nervous system diseases. Within the past year, molecular cloning of the first glutamate receptor channel and several related subunits has opened new approaches for understanding the basis of these important phenomena.  相似文献   

12.
《FEBS letters》2014,588(8):1389-1395
In recent years it has become evident that gap junctions and hemichannels, in concert with extracellular ATP and purinergic receptors, play key roles in several physiological processes and pathological conditions. However, only recently has their importance in infectious diseases been explored, likely because early reports indicated that connexin containing channels were completely inactivated under inflammatory conditions, and therefore no further research was performed. However, recent evidence indicates that several infectious agents take advantage of these communication systems to enhance inflammation and apoptosis, as well as to participate in the infectious cycle of several pathogens. In the current review, we will discuss the role of these channels/receptors in the pathogenesis of several infectious diseases and the possibilities of generating novel therapeutic approaches to reduce or prevent these diseases.  相似文献   

13.
14.
Our interest in the preparation of a new type of biologically active substances led us to investigate the reaction between organophosphates and organomercurials. O-Arylmercuric O,O-dialkyl thiophosphates (I) were synthesized by several methods from arylmercuric chloride and O,O-dialkyl thiophosphate in the presence of silver. Likewise several approaches to the synthesis of arylmercuric dialkyl thiophosphate (II) were made. Dialkyldithiophosphate and organomercurial reacted readily in several organic solvents to yield mercury bis(dialkyl dithiophosphate) (IV).  相似文献   

15.
Examination of some collections from several late Miocene Turkish localities allows us to describe and definitely identify for the first time several species of spiral-horned antelopes in this country:Palaeoreas lindermayeri, Protragelaphus skouzesi, Prostrepsiceros zitteli andNisidorcas sp. During the first part of the late Miocene, several endemic species are restricted to central Anatolia, while more widespread taxa appear in the later part of this period, suggesting a decrease in provinciality of this area.  相似文献   

16.
International Journal of Peptide Research and Therapeutics - In the last decade, several studies have reported health beneficial effects of milk derived bioactive peptides in several degenerative...  相似文献   

17.
Bioprocess and Biosystems Engineering - Morus alba L. (Moraceae) has been used in traditional medicine for the treatment of several illnesses. Recent research also revealed several pharmacological...  相似文献   

18.
The etiology of several neurodegenerative disorders is thought to involve impaired mitochondrial function and oxidative stress. Coenzyme Q-10 (CoQ10) acts both as an antioxidant and as an electron acceptor at the level of the mitochondria. In several animal models of neurodegenerative diseases including amyotrophic lateral sclerosis, Huntington’s disease, and Parkinson’s disease, CoQ10 has shown beneficial effects. Based on its biochemical properties and the effects in animal models, several clinical trials evaluating CoQ10 have been undertaken in many neurodegenerative diseases. CoQ10 appears to be safe and well tolerated, and several efficacy trials are planned.  相似文献   

19.
During apoptosis, there is a reduction in translation initiation caused by caspase cleavage of several of the factors required for the cap-dependent scanning mechanism. Under these circumstances, many proteins that are required for apoptosis are instead translated by the alternative method of internal ribosome entry. This mechanism requires the formation of a complex RNA structural element and in the presence of internal ribosome entry segment (IRES)-trans-acting factors (ITAFs), the ribosome is recruited to the RNA. The interactions of several ITAFs with IRESs have been investigated in detail, and several mechanisms of action have been noted, including acting as chaperones, stabilising and remodelling the RNA structure. Structural remodelling by PTB in particular will be discussed, and how this protein is able to facilitate recruitment of the ribosome to several IRESs by causing previously occluded sites to become more accessible.  相似文献   

20.
Cholangiocytes, like most cells, express primary cilia extending from their membranes. These organelles function as antennae which detect stimuli from bile and transmit the information into cells regulating several signaling pathways involved in secretion, proliferation and apoptosis. The ability of primary cilia to detect different signals is provided by ciliary associated proteins which are expressed in its membrane. Defects in the structure and/or function of these organelles lead to cholangiociliopathies that result in cholangiocyte hyperproliferation, altered fluid secretion and absorption. Since primary cilia dysfunction has been observed in several epithelial tumors, including cholangiocarcinoma (CCA), primary cilia have been proposed as tumor suppressor organelles. In addition, the loss of cilia is associated with dysregulation of several molecular pathways resulting in CCA development and progression. Thus, restoration of the primary cilia may be a potential therapeutic approach for several ciliopathies and CCA.  相似文献   

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