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Pinocytosis as measured by the uptake of 125I labelled PVP by the isolated cultured day 12 rat yolk sac was observed to be linear over a 4 h incubation period and to proceed at a rate of approximately 2.5 microliters/mg protein/h. Cadmium, anti-visceral yolk sac antibody (AVYS) and trypan blue all inhibited pinocytosis in a concentration-dependent fashion when added to the culture medium, although at low concentrations trypan blue was slightly stimulatory. The effect of zinc on the inhibition of pinocytosis by these three teratogens was studied. It was observed that zinc ameliorated the inhibitory effects of cadmium and AVYS, but had no effect on inhibition by trypan blue. These results indicate that the previously demonstrated protective action of zinc against cadmium-induced yolk sac dysfunction is not specific to that agent but extends to inhibition of pinocytosis by AVYS, and further suggest that, because of its refractoriness to zinc, trypan blue-induced inhibition of pinocytosis by yolk sac occurs by a mechanism different from that effected by cadmium and AVYS. 相似文献
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On the production,elemental composition (C,N, P) and distribution of photosynthetic organic matter in the Southern Black Sea 总被引:2,自引:1,他引:1
Yılmaz Ayşen Tuğrul Süleyman Polat Çolpan Ediger Dilek Çoban Yeşim Morkoç Enis 《Hydrobiologia》1997,363(1-3):141-155
Chemical oceanographic understanding of the southernBlack Sea has been improved by recent measurements ofthe optical transparency,
phytoplankton biomass (interms of chlorophyll-a and particulate organic matter)and primary productivity. During the spring-autmunperiod
of 1995–1996, light generally penetrated onlyinto the upper 15–40 m, with an attenuation coefficientvarying between 0.125
and 0.350 m2122;1. The averagechlorophyll-a (Chl-a) concentrations for the euphoticzone ranged from 0.1 to 1.5 μg l2122;1. Coherentsub-surface Chl-a maxima were formed near the base ofthe euphotic zone only in summer. Production rate variedbetween
247 and 1925 in the spring and between 405 and687 mgC m2122;2 d2122;1 in the summer-autumn period.The average POM concentrations in the euphotic zonevaried regionally and seasonally between 3.8
and28.6 μm for POC, 0.5 and 3.1 μm for PON and0.02 and 0.1 μm for PP. Atomic ratios of C/N, C/Pand N/P, derived from the regressions
of POM data,ranged between 7.5 and 9.6, 109 and 165, and 11.2 and16.6, respectively. In the suboxic/anoxic interface,the elemental
ratios change substantially due to anaccumulation of PP cohering to Fe and Mn oxides. Thechemocline boundaries and the distinct
chemicalfeatures of the oxic/anoxic transition layer (the so-called suboxic zone) are all located at specificdensity surfaces;
however, they exhibit remarkablespatial and temporal variations both in their positionand in their magnitude, which permit
the definition of long-term changes in the biochemical properties of theBlack Sea upper layer.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
4.
Malocclusions of the premolar and molar teeth of inbred Strain 2/N and Strain 13/N and outbred Dunkin-Harley guinea pigs were examined. A higher incidence of malocclusion observed in the inbred strains suggested a genetic basis for the disorder. 相似文献
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álvaro Menin Renata Fleith Carolina Reck Mariel Marlow Paula Fernandes Célso Pilati André Báfica 《PloS one》2013,8(1)
Rational discovery of novel immunodiagnostic and vaccine candidate antigens to control bovine tuberculosis (bTB) requires knowledge of disease immunopathogenesis. However, there remains a paucity of information on the Mycobacterium bovis-host immune interactions during the natural infection. Analysis of 247 naturally PPD+ M. bovis-infected cattle revealed that 92% (n = 228) of these animals were found to display no clinical signs, but presented severe as well as disseminated bTB-lesions at post-mortem examination. Moreover, dissemination of bTB-lesions positively correlated with both pathology severity score (Spearman r = 0.48; p<0.0001) and viable tissue bacterial loads (Spearman r = 0.58; p = 0.0001). Additionally, granuloma encapsulation negatively correlated with M. bovis growth as well as pathology severity, suggesting that encapsulation is an effective mechanism to control bacterial proliferation during natural infection. Moreover, multinucleated giant cell numbers were found to negatively correlate with bacterial counts (Spearman r = 0.25; p = 0.03) in lung granulomas. In contrast, neutrophil numbers in the granuloma were associated with increased M. bovis proliferation (Spearman r = 0.27; p = 0.021). Together, our findings suggest that encapsulation and multinucleated giant cells control M. bovis viability, whereas neutrophils may serve as a cellular biomarker of bacterial proliferation during natural infection. These data integrate host granuloma responses with mycobacterial dissemination and could provide useful immunopathological-based biomarkers of disease severity in natural infection with M. bovis, an important cattle pathogen. 相似文献
7.
Sreelaja Nair Florence Marlow Elliott Abrams Lee Kapp Mary C. Mullins Francisco Pelegri 《PLoS genetics》2013,9(4)
Microtubule-microfilament interactions are important for cytokinesis and subcellular localization of proteins and mRNAs. In the early zebrafish embryo, astral microtubule-microfilament interactions also facilitate a stereotypic segregation pattern of germ plasm ribonucleoparticles (GP RNPs), which is critical for their eventual selective inheritance by germ cells. The precise mechanisms and molecular mediators for both cytoskeletal interactions and GP RNPs segregation are the focus of intense research. Here, we report the molecular identification of a zebrafish maternal-effect mutation motley as Birc5b, a homolog of the mammalian Chromosomal Passenger Complex (CPC) component Survivin. The meiosis and mitosis defects in motley/birc5b mutant embryos are consistent with failed CPC function, and additional defects in astral microtubule remodeling contribute to failures in the initiation of cytokinesis furrow ingression. Unexpectedly, the motley/birc5b mutation also disrupts cortical microfilaments and GP RNP aggregation during early cell divisions. Birc5b localizes to the tips of astral microtubules along with polymerizing cortical F-actin and the GP RNPs. Mutant Birc5b co-localizes with cortical F-actin and GP RNPs, but fails to associate with astral microtubule tips, leading to disorganized microfilaments and GP RNP aggregation defects. Thus, maternal Birc5b localizes to astral microtubule tips and associates with cortical F-actin and GP RNPs, potentially linking the two cytoskeletons to mediate microtubule-microfilament reorganization and GP RNP aggregation during early embryonic cell cycles in zebrafish. In addition to the known mitotic function of CPC components, our analyses reveal a non-canonical role for an evolutionarily conserved CPC protein in microfilament reorganization and germ plasm aggregation. 相似文献
8.
Dorsoventral patterning of the embryonic axis relies upon the mutual antagonism of competing signaling pathways to establish a balance between ventralizing BMP signaling and dorsal cell fate specification mediated by the organizer. In zebrafish, the initial embryo-wide domain of BMP signaling is refined into a morphogenetic gradient following activation dorsally of a maternal Wnt pathway. The accumulation of β-catenin in nuclei on the dorsal side of the embryo then leads to repression of BMP signaling dorsally and the induction of dorsal cell fates mediated by Nodal and FGF signaling. A separate Wnt pathway operates zygotically via Wnt8a to limit dorsal cell fate specification and maintain the expression of ventralizing genes in ventrolateral domains. We have isolated a recessive dorsalizing maternal-effect mutation disrupting the gene encoding Integrator Complex Subunit 6 (Ints6). Due to widespread de-repression of dorsal organizer genes, embryos from mutant mothers fail to maintain expression of BMP ligands, fail to fully express vox and ved, two mediators of Wnt8a, display delayed cell movements during gastrulation, and severe dorsalization. Consistent with radial dorsalization, affected embryos display multiple independent axial domains along with ectopic dorsal forerunner cells. Limiting Nodal signaling or restoring BMP signaling restores wild-type patterning to affected embryos. Our results are consistent with a novel role for Ints6 in restricting the vertebrate organizer to a dorsal domain in embryonic patterning. 相似文献
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