排序方式: 共有9条查询结果,搜索用时 31 毫秒
1
1.
Proline-rich antimicrobial peptides are a group of cationic host defense peptides of vertebrates and invertebrates characterized
by a high content of proline residues, often associated with arginine residues in repeated motifs. Those isolated from some
mammalian and insect species, although not evolutionarily related, use a similar mechanism to selectively kill Gram-negative
bacteria, with a low toxicity to animals. Unlike other types of antimicrobial peptides, their mode of action does not involve
the lysis of bacterial membranes but entails penetration into susceptible cells, where they then act intracellularly. Some
aspects of the transport system and cytoplasmic targets have been elucidated. These features make them attractive both as
anti-infective lead compounds and as a new class of potential cell-penetrating peptides capable of internalising membrane-impermeant
drugs into both bacterial and eukaryotic cells 相似文献
2.
Barbara Di Gennaro Splendore 《Annals of science》2013,70(2):91-107
The apothecary occupied a liminal position in early modern society between profit and healing. Finding ways to distance their public image from trade was a common problem for apothecaries across Europe. This article uses the case of a Bolognese apothecary, Filippo Pastarino, to address the question of how early modern apothecaries chose to represent themselves to political authorities and to the wider public. ‘Mercy’, alongside ‘craft’, was a pillar of apothecaries’ social identity. By contrast, no matter how central financial transactions (‘money’) were to their activity, apothecaries did not want to be perceived as merchants. Thus, the assistance and advice apothecaries provided to patients and customers resulted as central aspects of their social role. In this context, Bolognese apothecaries aimed to defend their current status, which had been challenged by naturalist Ulysses Aldrovandi, city authorities and local monasteries. However, Pastarino's claims can also be seen as antecedents to the self-legitimizing strategy that seventeenth-century artisans deployed when faced with the need to enhance their new status as natural philosophers. The present study attributes a name, a date of birth and a shop to Filippo Pastarino, revising previous interpretations. More broadly, by focusing on how these artisans defended their position in the city it enriches our understanding of the self-representation of apothecaries. 相似文献
3.
4.
5.
Endocytosis of the major histocompatibility complex (MHC)-encoded class I and class II molecules has been the subject of recent investigations. Class I molecules, which are key elements in T cell-mediated cytotoxicity, are differentially endocytosed by different cell types. Fibroblasts internalize their class I molecules via uncoated cell surface vesicles and tubular invaginations when these molecules are cross-linked with multivalent ligands. T lymphocytes internalize their class I molecules spontaneously, but B lymphocytes do not internalize them at all. Here we describe a morphological investigation of the mechanism by which class I molecules are endocytosed by T lymphocytes. We show that, unlike fibroblasts, T lymphocytes spontaneously internalize 20-40% of their class I molecules in a process involving coated pits and coated vesicles. Thus, the endocytic pathway of class I molecules in T lymphocytes is similar to those of other more classical cell-surface receptors involved in receptor-mediated endocytosis. In contrast, the same class I molecules remained on the cell surface in B lymphocytes. These data show that class I molecules are differentially regulated in T and B lymphocytes and fibroblasts. 相似文献
6.
This study presents the first food habit assessment for the western whiptail lizard ( Cnemidophorus tigris ) in the shinnery oak – mesquite habitat ( Quercus havardii – Prosopis glandulosa ) of southeastern New Mexico. Short-horned grasshoppers, termites, antlions, beetles, and spiders formed the major portion of the diet during the four-year study. Discriminant analyses were used to evaluate annual, seasonal (monthly), and sexual variation. Incidental food categories were responsible for most of the annual and seasonal variation. Dominant foods varied little between months and years. Sexual variation was more evident; it may act to reduce intraspecific competition for food resources and may be associated with secondary sexual size dimorphism. 相似文献
7.
8.
9.
G. Bacci Marina Lanfranco Ines Mantello Mariangela Tomba 《Cellular and molecular life sciences : CMLS》1979,35(5):605-606
Summary A new kind of hermaphroditism, which is called inducible hermaphroditism, has been discovered in the otherwise gonochoristic populations ofOphryotrocha labronica of the Gulf of Naples and of the Lagune of Venice. Inducible hermaphrodites, which are fertile in both the male and female phases, represent 25.8% and 31.8% of the Naples and Venice strains respectively. Inducible hermaphrodites are obtained when pairs between adult females — or female phase hermaphrodites — and juveniles are formed. Crosses between inducible hermaphrodites, in different sex phases, pure male and female individuals give progenies whose sex ratios are clearly correlated with the sex genotypes of the parents. 相似文献
1