Biodiversity of stream insects in the Malaysian Peninsula: spatial patterns and environmental constraints

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Two mechanisms of near-ultraviolet lethality in Saccharomyces cerevisiae: A respiratory capacity-dependent and an irreversible inactivation

Near-ultraviolet irradiation of actively growing yeast cells leads to cell death by two distinct mechanisms. The first type of cell death is evident after low doses of near-ultraviolet light (3 · 10⁴ ergs · mm⁻²) and is due to a areversible inactivation of the respiratory capacity of the cell. In studies with yeast mitochondrial membranes the quinones were identified as the site of inactivation by determining the relative levels of the following oxidase activities after irradiation: exogenous NADH, endogenous NADH (via isocitrate dehydrogenase), succinate, and D-lactate oxidases. A second type of cell death is caused after high doses (1.8 · 10⁵ ergs · mm⁻²) and is irreversible. The mechanism of this inactivation is unknown.     

Morphological development and characterization of aromatase and estrogen receptors alpha and beta in fetal ovaries of cattle from days 110 to 250

To better understand the role of estradiol-17β in fetal ovarian development, presence and localization of cytochrome P450 aromatase (P450arom) and estrogen receptors alpha (ERα) and beta (ERβ) proteins were characterized in fetal ovaries of cattle using immunohistochemistry. Fetal cattle ovaries were collected from an abattoir and sorted into fetal age groups (days 110, 130, 150, 170, 190, 210, 230, 250+) based on crown-rump length. In addition to immunohistochemistry, morphological analysis of ovarian and follicular formation was made. Ovaries appeared lobular at day 110, but by the end of gestation (day 250+) ovaries were oval-shaped similar to those found in adult animals. Ovarian structures within different lobes appeared to be at different developmental stages. At day 110, oocytes and pre-granulosa cells were observed in ovigerous cords that were still open to the surface epithelium. Most ovigerous cords appeared to be closed to the surface epithelium on day 130, all closed by day 150 and were no longer present at day 210. Ovarian follicles were classified as follows: Type 1(primordial): single layer of flattened granulosa cells, Type 1a (transitory): single layer of mixed flattened and cuboidal granulosa cells, Type 2 (primary): at least one but less than two layers of cuboidal granulosa cells, Type 3 (small preantral): two to three layers of granulosa cells, Type 4 (large preantral): four to six layers of granulosa, and the theca layer is forming around the follicle, Type 5 (antral): contain greater than six layers of granulosa cells, several layers of theca cells and the antrum has formed. Type 1 follicles were observed in day 110 ovaries. Follicle Types 1a and 2 were first observed on day 130. Type 3 follicles were first observed on day 150 and Types 4 and 5 were first observed on day 170. P450arom protein was localized in granulosa cells of follicle Types 2–5 and cells of rete tubules throughout the experimental period. There was punctate expression within stroma and rete masses. There was ERα protein localization in pre-granulosa cells and germ cells of ovigerous cords and all surface epithelial cells. There was also localization in granulosa cells and oocytes of all follicle types and cells of rete tubules. There was punctate ERα protein expression in stroma and rete masses. ERβ protein was localized in pre-granulosa cells and germ cells of ovigerous cords. Expression was also localized to granulosa cells of all follicle types and cells of rete tubules. ERβ protein was punctate in oocytes of follicles, surface epithelial cells, stroma and rete masses. Thus, the fetal ovary of cattle has the steroidogenic enzyme (P450arom) to convert androgens to estradiol-17β, and estrogen receptors α and β to facilitate an estrogen response within the fetal ovary.     

The capsid protein of beak and feather disease virus binds to the viral DNA and is responsible for transporting the replication-associated protein into the nucleus

Circoviruses lack an autonomous DNA polymerase and are dependent on the replication machinery of the host cell for de novo DNA synthesis. Accordingly, the viral DNA needs to cross both the plasma membrane and the nuclear envelope before replication can occur. Here we report on the subcellular distribution of the beak and feather disease virus (BFDV) capsid protein (CP) and replication-associated protein (Rep) expressed via recombinant baculoviruses in an insect cell system and test the hypothesis that the CP is responsible for transporting the viral genome, as well as Rep, across the nuclear envelope. The intracellular localization of the BFDV CP was found to be directed by three partially overlapping bipartite nuclear localization signals (NLSs) situated between residues 16 and 56 at the N terminus of the protein. Moreover, a DNA binding region was also mapped to the N terminus of the protein and falls within the region containing the three putative NLSs. The ability of CP to bind DNA, coupled with the karyophilic nature of this protein, strongly suggests that it may be responsible for nuclear targeting of the viral genome. Interestingly, whereas Rep expressed on its own in insect cells is restricted to the cytoplasm, coexpression with CP alters the subcellular localization of Rep to the nucleus, strongly suggesting that an interaction with CP facilitates movement of Rep into the nucleus.