Studies on the mechanism for entry of vesicular stomatitis virus glycoprotein g mRNA into membrane-bound polyribosome complexes

Glycoprotein mRNA (G mRNA) of vesicular stomatitis virus is synthesized in the cytosol fraction of infected HeLa cells. Shortly after synthesis, this mRNA associates with 40S ribosomal subunits and subsequently forms 80S monosomes in the cytosol fraction. The bulk of labeled G mRNA is then found in polysomes associated with the membrane, without first appearing in the subunit or monomer pool of the membrane-bound fraction. Inhibition of the initiation of protein synthesis by pactamycin or muconomycin A blocks entry of newly synthesized G m RNA into membrane-bound polysomes. Under these circumstances, labeled G mRNA accumulates into the cytosol. Inhibition of the elongation of protein synthesis by cucloheximide, however, allows entry of 60 percent of newly synthesized G mRNA into membrane-bound polysomes. Furthermore, prelabeled G mRNA associated with membrane-bound polysomes is released from the membrane fraction in vivo by pactamycin or mucomycon A and in vitro by 1mM puromycin - 0.5 M KCI. This release is not due to nonspecific effects of the drugs. These results demonstrate that association of G mRNA with membrane-bound polysomes is dependent upon polysome formation and initiation of protein synthesis. Therefore, direct association of the 3' end of G mRNA with the membrane does not appear to be the initial event in the formation of membrane-bound polysomes.     

Hip joint replacement surgery for idiopathic osteoarthritis aggregates in families

In order to determine whether there is a genetic component to hip or knee joint failure due to idiopathic osteoarthritis (OA), we invited patients (probands) undergoing hip or knee arthroplasty for management of idiopathic OA to provide detailed family histories regarding the prevalence of idiopathic OA requiring joint replacement in their siblings. We also invited their spouses to provide detailed family histories about their siblings to serve as a control group. In the probands, we confirmed the diagnosis of idiopathic OA using American College of Rheumatology criteria. The cohorts included the siblings of 635 probands undergoing total hip replacement, the siblings of 486 probands undergoing total knee replacement, and the siblings of 787 spouses. We compared the prevalence of arthroplasty for idiopathic OA among the siblings of the probands with that among the siblings of the spouses, and we used logistic regression to identify independent risk factors for hip and knee arthroplasty in the siblings. Familial aggregation for hip arthroplasty, but not for knee arthroplasty, was observed after controlling for age and sex, suggesting a genetic contribution to end-stage hip OA but not to end-stage knee OA. We conclude that attempts to identify genes that predispose to idiopathic OA resulting in joint failure are more likely to be successful in patients with hip OA than in those with knee OA.     

饲喂黄曲霉毒素B_1大鼠肝中AFB_1-DNA加合物的免疫组织化学研究

应用免疫组织化学ＳＰ法对４例饲喂黄曲霉毒素Ｂ１的Ｗｉｓｔａｒ大鼠肝组织中ＡＦＢ１－ＤＮＡ加合物的染色及常规ＨＥ染色发现,４例肝细胞核均出现异型性,但未见肝细胞坏死、增生灶及肝细胞癌;免疫组化揭示部分肝细胞核出现棕黄色、不均质状的ＡＦＢ１－ＤＮＡ加合物,阳性细胞数占１０～８５％。结果提示免疫组织化学方法可作为一种ＡＦＢ１的定位方法,ＡＦＢ１在动物致癌过程中ＡＦＢ１－ＤＮＡ加合物可能具有启动作用     

Encounter with New Resources Causes Polarized Growth of the Cord-Forming Basidiomycete Phanerochaete velutina on Soil

Abstract The development and physiology of cord-forming saprotrophic basidiomycetes, which form extensive and persistent mycelial networks in woodland ecosystems, can be conveniently studied on non-sterile soil in laboratory microcosms mimicking field conditions. Morphological responses of Phanerochaete velutina mycelial systems to resource encounters, and decay partitioning following encounters, varied according to whether simulated woody litter was unsterile or autoclaved and on whether encounter took place at the mycelial foraging front or behind the margin (simulating litter fall onto established systems in the field). Results show that encounter of discrete resources by P. velutina is rapidly communicated to the entire mycelial system; that resource capture takes high priority at the expense of continued system extension and decay-derived carbon reallocation; and that polarized growth toward newly encountered resources, previously considered to occur infrequently with this species, may be readily detected using image analysis techniques. Potential advantages of polarized development of P. velutina are discussed.     

Cloning and expression of human aldose reductase

The complete amino acid sequence of human retina and muscle aldose reductase was determined by nucleotide analysis of cDNA clones isolated using synthetic oligonucleotide probes based on partial amino acid sequences of purified human psoas muscle aldose reductase. The cDNA sequence differs substantially in the noncoding and coding regions of recently published sequences of this enzyme. The mRNA for aldose reductase was abundantly expressed in HeLa cells, but only scarcely in a neuroblastoma cell line. Recombinant baculovirus containing one of the muscle cDNA clones was constructed and used to infect Spodoptera frugiperda (SF9) cells. A prominent protein with an apparent molecular size of 36 kDa was identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the culture medium as well as in the homogenate of SF9 cells after 2 days of infection. Culture medium or the supernatant fraction of cell homogenates containing this protein had high aldose reductase activity which showed characteristics of the reported human enzyme. These findings indicate that the amino acid sequence reported in this paper represents human retina and muscle aldose reductase and that functional human aldose reductase can be expressed in large amounts in a baculovirus expression system. The result should facilitate refined structural analysis and the development of new specific aldose reductase inhibitors for the treatment of diabetic complications.     

Adenosine and related compounds counteract tumor necrosis factor-alpha inhibition of neutrophil migration: implication of a novel cyclic AMP-independent action on the cell surface

Human rTNF-alpha (greater than or equal to U/ml) decreased PMN nondirected and directed migration to FMLP to approximately 50% of control. Adenosine (100 microM) almost completely restored hrTNF-inhibited migration (nondirected from 54 to 92% and directed migration to from 54 to 93% of control). The lowest concentration of adenosine that restored hrTNF-inhibited migration was 3 microM, and the adenosine analogue, 5'-(N-cyclopropyl)-carboxamido-adenosine (CPCA) was more potent than adenosine. Although CPCA binds to A2-receptors and stimulates adenylate cyclase, the reversal of hrTNF-inhibited chemotaxis was found to be independent of both PMN cAMP content and binding to A2-receptors, because neither 8-Br-cAMP nor pertussis adenylate cyclase restored hrTNF-inhibited PMN chemotaxis and the A2-receptor antagonist, 1,3-dipropyl-7-methylxanthine decreased CPCA stimulated cAMP but enhanced CPCA-restoration of hrTNF-inhibited chemotaxis. The effect of adenosine could be augmented by inhibition of adenosine uptake and decreased by adenosine deamination. Pentoxifylline, (3,7 dimethyl-1-[5 oxo-hexyl] xanthine), like adenosine also restored PMN chemotaxis inhibited by hrTNF. The adenosine receptor antagonist, 1,3-dipropyl-8(phenyl-p-acrylate)-xanthine (BW A1433U), decreased restoration of hrTNF-inhibited chemotaxis by CPCA or pentoxifylline. Thus, the inhibitory effect of hrTNF on PMN migration can be counteracted by adenosine, CPCA, pentoxifylline, and compounds that increase adenosine availability to the surface of the PMN. Inasmuch as an A1-selective agonist N6-cyclopentyladenosine was less active, and the action of the A2-selective agonist CPCA was enhanced by an A2-receptor antagonist, we hypothesize that neither A1 or A2 receptors are involved in adenosine restoration of hrTNF-inhibited chemotaxis. Further, increased cAMP, an A2-regulated event, does not cause the effect, and adenosine restoration of hrTNF-inhibited migration does not appear to be mediated by changes in PMN [F-actin], FMLP receptor expression, or cytosolic calcium. Hence, the restoration of hrTNF-inhibited chemotaxis is controlled by a novel cyclic AMP-independent action on the PMN surface.     

Plant–animal interactions in suburban environments: implications for floral evolution

Plant interactions with mutualists and antagonists vary remarkably across space, and have played key roles in the ecology and evolution of flowering plants. One dominant form of spatial variation is human modification of the landscape, including urbanization and suburbanization. Our goal was to assess how suburbanization affected plant–animal interactions in Gelsemium sempervirens in the southeastern United States, including interactions with mutualists (pollination) and antagonists (nectar robbing and florivory). Based on differences in plant–animal interactions measured in multiple replicate sites, we then developed predictions for how these differences would affect patterns of natural selection, and we explored the patterns using measurements of floral and defensive traits in the field and in a common garden. We found that Gelsemium growing in suburban sites experienced more robbing and florivory as well as more heterospecific but not conspecific pollen transfer. Floral traits, particularly corolla length and width, influenced the susceptibility of plants to particular interactors. Observational data of floral traits measured in the field and in a common garden provided some supporting but also some conflicting evidence for the hypothesis that floral traits evolved in response to differences in species interactions in suburban vs. wild sites. However, the degree to which plants can respond to any one interactor may be constrained by correlations among floral morphological traits. Taken together, consideration of the broader geographic context in which organisms interact, in both suburban and wild areas, is fundamental to our understanding of the forces that shape contemporary plant–animal interactions and selection pressures in native species.     

Intestinal barrier function in response to abundant or depleted mucosal glutathione in Salmonella-infected rats

Background  

Glutathione, the main antioxidant of intestinal epithelial cells, is suggested to play an important role in gut barrier function and prevention of inflammation-related oxidative damage as induced by acute bacterial infection. Most studies on intestinal glutathione focus on oxidative stress reduction without considering functional disease outcome. Our aim was to determine whether depletion or maintenance of intestinal glutathione changes susceptibility of rats to Salmonella infection and associated inflammation.