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1.
2.
There is a phosphopeptide that has an Mr of 53,000 to 60,000 in insulin-secreting tissues and there is general agreement that this peptide can be phosphorylated in a calcium-dependent manner. The present report shows that there are at least two phosphoproteins with Mr's near 57,000 in rat pancreatic islet cytosol. One peptide has an Mr of 57,000, a pl of 7.5 - 8 and is phosphorylated in a Ca2+-enhanced manner, and the other has an Mr of 54,000, a pl of 5 - 5.5 and is phosphorylated in a cAMP-enhanced manner, as judged by two-dimensional polyacrylamide gel electrophoresis. Sepharose 4B chromatography indicated that the former polypeptide resides in a native protein complex that has an Mr of about 500,000 and the latter in a complex that has an Mr of about 180,000. Tritiated azido cyclic AMP binds to an islet polypeptide that has an Mr of 54,000. The results suggest that Ca2+ and cAMP could regulate stimulus-secretion coupling in pancreatic islets via protein phosphorylation.  相似文献   

3.
《Anthrozo?s》2013,26(4):204-215
ABSTRACT

This experimental study examines how framing an animal species as endangered affects its perceived attractiveness and how an animal's perceived attractiveness affects support for its conservation. Undergraduate students were shown a flyer from a fictitious environmental organization pleading for the protection of either a bat or an ape. The flyer contained either no picture, a picture of an attractive member of its species, or a picture of an unattractive member of its species. For both species, an animal's attractiveness substantially increased support for its protection. There was also more support for saving the species that was larger in size and more resembled humans. In a second experiment, participants rated an unattractive animal as more attractive if it was framed as endangered. There was no such effect for an animal originally perceived as attractive. The implications of the results for environmental policy and conservation support are discussed.  相似文献   

4.
A white Rhodesian living in South Africa tells an ethnographer the story of his experiences as a charismatic Christian and a veteran of warfare involving terrorism. Like a testimony, the story is designed to produce an effect on its hearer. With an ethnopsychiatric approach, such a story must be understood dialogically, as an exchange in which a game of "who has the emotion" is played.  相似文献   

5.
Meng X  Zhang C  Chen J  Peng S  Cao Y  Ying K  Xie Y  Mao Y 《Biochemical genetics》2003,41(3-4):99-106
Thioredoxin plays an important role in various cellular processes through redox regulation. Here we report the molecular cloning and characterization of one member of the thioredoxin superfamily, designated as TMX2. The TMX2 cDNA consists of 1644 nucleotides and contains an open reading frame encoding a protein of 372 amino acids with a predicted molecular mass of 42.5 kDa and an isoelectric point of 8.94 . The TMX2 protein may possess an N-terminal signal peptide, a potential transmembrane domain, an Myb DNA-binding domain repeat signature, a thioredoxin consensus pattern, an endoplasmic reticulum (ER) membrane retention signal (KKXX-like motif), and a dileucine motif in the tail. Northern blot analysis shows it is widely expressed in human tissues.  相似文献   

6.
In healthy humans after overnight fasting, an oral administration of ornithine induced a new steady state: an accumulation of serum alanine and proline, a decrease in serum valine concentration, transient reductions in serum urea and urinary urea contents, and then an increased urea excretion. On the other hand, an oral administration of arginine resulted in an anabolic state: decreases in serum leucine and isoleucine concentrations, reductions in serum glucose and free fatty acid contents and a rapid increase in serum insulin level. It was assumed that the effect of ornithine administration may be exerted through an activation of hepatic System A transport and that of arginine is an insulin-mediated action.  相似文献   

7.
The detection of DNA polymorphisms by RFLP analysis is having a major impact on identity testing in forensic science. At present, this approach is the best effort a forensic scientist can make to exclude an individual who has been falsely associated with an evidentiary sample found at a crime scene. When an analysis fails to exclude a suspect as a potential contributor of an evidentiary sample, a means should be provided to assess suitable weight to the putative match. Most important, the statistical analysis should not place undue weight on a genetic profile derived from an unknown sample that is attributed to an accused individual. The method must allow for limitations in conventional agarose-submarine-gel electrophoresis and Southern blotting procedure, limited sample population data, possible subpopulation differences, and potential sampling error. A conservative statistical method was developed based on arbitrarily defined fixed bins. This approach permits classification of continuous allelic data, provides for a simple and portable data-base system, and is unlikely to underestimate the frequency of occurrence of a set of alleles. This will help ensure that undue weight is not placed on a sample attributed to an accused individual.  相似文献   

8.
Unstable anthocyanin3 (an3) alleles of petunia with insertions of the Activator/Dissociation-like transposon dTph1 fall into two classes that differ in their genetic behavior. Excision of the (single) dTph1 insertion from class 1 an3 alleles results in the formation of a footprint, similar to the "classical" mechanism observed for excisions of maize and snapdragon transposons. By contrast, dTph1 excision and gap repair in class 2 an3 alleles occurs via a newly discovered mechanism that does not generate a footprint at the empty donor site. This novel mechanism depends on the presence of two additional dTph1 elements: one located in cis, 30 bp upstream of the an3 translation start in the same an3 allele, and a homologous copy, which is located in trans in the homologous an3 allele. Absence of the latter dTph1 element causes a heritable suppression of dTph1 excision-repair from the homologous an3 allele by the novel mechanism, which to some extent resembles paramutation. Thus, an epigenetic interaction among three dTph1 copies activates a novel recombination mechanism that eliminates a transposon insertion.  相似文献   

9.
He C  Dey M  Lin Z  Duan F  Li F  Wu R 《Genomics》2007,89(4):532-540
Generation of an indexed, saturated, insertional-mutant library is an aid to understanding the functions of genes in an organism. However, 10 years of work by many investigators have not yet yielded such a library in rice. The major reason is that determining the chromosomal locations of a very large number of random insertion mutants by flanking sequence analysis is highly labor intensive, and therefore, libraries that do exist have not been indexed. We report here an efficient procedure to construct an indexed, region-specific, insertional-mutant library of rice. The procedure makes use of efficient long-PCR-based high-throughput indexing, coupled with a random but anchored population of Ds transposants. Long-PCR indexing allows rapid and simultaneous determination of the chromosomal locations of a large number of mutants that surround a particular anchor line, thus converting a random library into an indexed one. Such a library can be used directly, without the need to screen a large random library for a desired mutant plant.  相似文献   

10.
对地钱(Marchantia polymorpha)颈卵器发育和卵发生过程进行了显微观察和细胞化学的研究,颈卵器起始于原始细胞,该细胞呈乳突状,经横分裂产生基细胞和顶细胞,顶细胞经3次纵斜向分裂和1次横分裂产生初生细胞,初生细胞是颈卵器内的第一个细胞,经横分裂产生中央细胞和颈沟母细胞,前者产生1个腹沟细胞和1个卵细胞,后者最终产生4个颈沟细胞。颈卵器的成熟表现为颈部显著伸长和腹部膨大,卵细胞成熟时具有不规则的核,细胞质内含有丰富的囊泡和颗粒物,卵细胞周围充满粘性物质,细胞化学研究表明,该粘性物质为多糖,卵细胞质中深染色的颗粒可能为脂类物质,腹沟细胞自产生后就逐渐退化,颈沟细胞的退化迟于腹沟细胞,其数量通常为4个,偶尔可见5个颈沟细胞或具有双核的现象。  相似文献   

11.
Under certain conditions it is shown that an extended culture is equivalent to an exponentially-fed-batch culture, that an exponentially-fed-batch culture (and an extended culture) can be maintained at a steady state and that an exponentially-fed-batch culture may be mimicked by a continuous-flow culture with a constant dilution rate. Operational conditions required to maintain steady states are specified.  相似文献   

12.
Different aspects and modifications of the definition of an evolutionarily stable (ES) strategy that have been considered in the literature can be incorporated in a unifying concept which regards the population context. This concept of evolutionary stability will generally characterize population states in both pure- and mixed-strategist models. In particular, it includes ES strategies, represented as a phenotype unique in an ES population. For an important class of mixed-strategist models, no strict ESS can exist. This will be the case whenever the success of an individual strategy is considered to follow as an average from the successes of its behavioural components. Instead, ESS results may be obtained from what will be called a “degenerate” form of the model, which is simply an ESS model on the level of elementary actions. Then, however, the correct interpretation of an ESS is not an individual phenotype but rather a population mixture of elementary actions. If an ES state exists in a mixed-strategist model it may be determined by an equilibrium condition; if there is an ES strategy, a different approach—mainly maximum considerations—is needed for finding it. An equilibrium condition does not hold for the components of an ES strategy straightforwardly; but it can be derived in terms of an auxiliary ESS model that considers first-order effects of the components. Several examples illustrate the significance of these results. Particularly, two models on “Games between Relatives” are reconsidered in order to display both their formal interrelation and the different meaning of their results in the context of mixed-strategist models.  相似文献   

13.
Female mice (Mus musculus) which were reared by a preputialectomized female and exposed to an intact male from 14 to 18 days of age preferred the odor of an intact male over that of a preputialectomized male when tested at 15 weeks of age. However, those females which were exposed to an intact male from 28 to 32 days of age preferred the odor of a preputialectomized male over that of an intact male, and those females which were exposed to an intact male from 0 to 4 days of age showed no reliable preferences. Females which were reared by an intact female and exposed a preputialectomized male for 4 days tended to reverse preferences. Females which were exposed to a preputialectomized male from 14 to 18 days of age preferred the odor of a preputialectomized male. However, females which were exposed to a preputialectomized male from 28 to 32 days of age preferred the odor of an intact male, as did females which were exposed to a preputialectomized male from 0 to 4 days.  相似文献   

14.
In an aggregation territory of Dictyostelium discoideum, outwardly moving, nondissipating waves of the chemoattractant cAMP sweep across each ameba. At the front of each wave, an ameba experiences an increasing temporal and a positive spatial gradient of cAMP. At the back of a wave, an ameba experiences a decreasing temporal and a negative spatial gradient of cAMP. Employing a perfusion chamber, we have mimicked the temporal dynamics of these waves in the absence of a spatial gradient and demonstrated that the frequency of lateral pseudopod formation and the frequency of turning are dramatically affected by the direction and dynamics of the temporal gradient. In addition, since an ameba will move in a directed fashion up a shallow, nonpulsatile gradient of cAMP, we also mimicked the increasing temporal gradient generated by an ameba moving up a shallow spatial gradient. The frequency of lateral pseudopod formation and the frequency of turning were depressed. Together, these results demonstrate that amebae can assess the direction of a temporal gradient of chemoattractant in the absence of a spatial gradient and alter both the frequency of pseudopod extension and turning, accordingly. Although these results do not rule out the involvement of a spatial mechanism in assessing a spatial gradient, they strongly suggest that the temporal dynamics of a cAMP wave or the temporal gradient generated by an ameba moving through a spatial gradient may play a major role in chemotaxis.  相似文献   

15.
The possibility of terminating cardiac arrhythmias with electric fields of moderate intensity is a challenging problem from a fundamental point of view and an important issue for clinical applications. In an effort to understand how anatomical re-entries are affected by electric fields, we found that a weak shock, with an amplitude of an order of magnitude less than the defibrillating shock, may unpin the vortices rotating around the defects (obstacles). The unpinning results from a depolarization of the tissue near the obstacle, induced by an external electric field within a distance of order lambda approximately 1 mm. Unpinning was observed both in the FitzHugh model of excitable tissue, and in a specific Beeler-Reuter model of cardiac tissue. This theoretical observation suggests that anatomical re-entries can be transformed into functional re-entries, an effect that can be tested in experiments with cardiac muscle.  相似文献   

16.
王桂萍   《微生物学通报》2003,30(6):87-88
目的是提供一种理想的微生物培养室使用的灭菌供暖供温干燥装置。该装置由炉体(5)和灭菌干燥系统,包括鼓风机(1)、吸气管(13)、进气管(2)、受热管(3)、出气管(4);供温系统,包括水锅(6)、水锅进气管(7)、出汽管(8)、控制阀(9);燃烧系统包括出烟筒(10)、灶门(11),4大部分组成。结构简单、实用。  相似文献   

17.
Chimpanzees of the Mahale Mountains, Tanzania were discovered to show an expressive gesture using leaves, termed as “leaf-clipping display”. This behavioural signal is directed by an adult male to an estrous female as a possessive behaviour, or by an adolescent male as a courtship display, or by an estrous female to an adolescent male also as a solicitation of copulation. The signal also is used toward human observers as a signal of food-demanding. This behaviour pattern might originate in a displacement tool-making behaviour in conflict situations. The leaf-clipping display has not been observed in any other chimpanzee populations studied, and may probably be one example of the tradition drift in wild chimpanzees.  相似文献   

18.
Using a linear model with age-dependence and spatial structure we show how a periodical supply of individuals will transform an exponentially decaying distribution of population into a non-trivial asymptotically stable periodic distribution. Next we give an application to an epidemic model.  相似文献   

19.
McBrayer JP 《Bioethics》2008,22(6):299-306
The non‐identity problem is the problem of grounding moral wrongdoing in cases in which an action affects who will exist in the future. Consider a woman who intentionally conceives while on medication that is harmful for a fetus. If the resulting child is disabled as a result of the medication, what makes the woman's action morally wrong? I argue that an explanation in terms of harmful rights violations fails, and I focus on Peter Markie's recent rights‐based defense. Markie's analysis rests on the notion of an indirect harm, and I show that the calculation of an indirect harm relies on an improper baseline for the determination of whether or not an action adversely affects a patient's interests. I also defend an impersonal duty‐based analysis of the wrongdoing in non‐identity cases against an objection by Markie. I close by arguing that the rights‐based analysis is insensitive to context and that context is morally relevant in the determination of the moral valence of actions in cases of non‐identity. This failure provides a pro tanto reason to favor an impersonal duty‐based analysis of the wrongdoing in non‐identity cases.  相似文献   

20.
An automated method for generating a fiber alignment map in tissues, tissue-equivalents, and other fibrillar materials exhibiting linear and circular optical properties and scattering is presented. This method consists of interrogating the sample with elliptically polarized light from a rotated quarter-wave plate and an effective circular analyzer, and implementing nonlinear regression techniques to estimate parameters defining the optical properties of the optic train and the sample. Thus, an account is made for imperfect and misaligned optic elements. The optic train was modeled using the Mueller matrix representation and the combined sample properties by an exponential matrix. Because a sample's Mueller matrix does not uniquely determine the linear, circular, or scattering properties, the circular properties and effective scattering are estimated for a matched isotropic sample to determine and correct for the linear birefringence of an aligned sample. The method's utility is demonstrated by generating an alignment map of an arterial media-equivalent, a relevant test case because of its circumferential alignment and thus showing the method's sample orientation independence.  相似文献   

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