Action of spontaneously produced beta interferon in differentiation of embryonal carcinoma cells through an autoinduction mechanism.

In the current study, we have addressed the role of interferons (IFNs) in controlling the differentiation of pluripotent P19 embryonal carcinoma (EC) cells. Blocking IFN activity in the culture medium of differentiating cells with antibodies leads to a strong decrease in the degree of differentiation. The antibodies are active for a relatively short time. During this time, IFN-beta mRNA can be detected in the differentiating cells, as can increases of IFN stimulation response element-binding activity and NF-KB. The timing of IFN action also coincides with the accumulation of cytoplasmic double-stranded RNA (dsRNA) and with a drop in dsRNA unwindase-modificase activity. A model for the involvement of autoinduction of IFN by intracellular dsRNA in the control of differentiation in this system is presented.     

Testis size,epididymis weight,and sperm competition in rhesus macaques

The intensity of sperm competition is often measured using the gonadosomatic index (testes/body weight). But sperm competition could be mediated more by size of the epididymis than by size of the testicles, and little information is available on the relationship between testicular and epididymal size. We found that both organs were positively correlated in size among male rhesus macaques. Body weight accounted for over 70% of the variance in testicle size and volumetric estimates of testicle size accurately reflected testicle weight. We conclude that methods for ascertaining testicle size are accurate, but the covariation in size between testicles and epididymis will hamper understanding of the physiological mechanisms involved in sperm competition in primates. © 1993 Wiley-Liss, Inc.     

Chemical and microbiological solubilization of silicates

The solubilization of silicates was investigated using kaolin and quartz sand as model substances. The mineral solubilization was studied in the concentration of solubilized Si and Al. The chemical leaching of the silicates was carried out using inorganic and organic acids as well as sodium hydroxide. The process was more effective in the alkine than in the acid pH range. In the acid medium, oxalic acid showed maximum acidity and a tendency to form complex structures, especially with aluminium, and was most effective in leaching. The microbiological influence on solubilization reactions was tested using a number of microorganisms among them acid, alkali and slime-forming species. The highest leaching activity was observed in the case of Thiobacillus thiooxidans, whereas the heterotrophic microorganisms (among them Bacillus mucilaginosus) did not exercise a sollubilizing effect on the silicates. X-ray phase analysis of leached kaolin samples did not show any differences from the non-leached mineral.     

Responses of production and storage walnut pests to Bacillus thuringiensis insecticidal crystal protein fragments

Recent advances in genetic engineering have provided the opportunity to induce walnut plants to produce Bacillus thuringiensis Berliner insecticidal crystal protein fragments (ICPFs) for insect control. We studied the effects of two ICPFs CryIA(b) and CrylA(c) previously shown to be encoded by the cryIA(b) and cryIA(c) genes in the B. thuringiensis strains HD-1 and HD-73, respectively. The lethal effects on larvae of codling moth, Cydia pomonella (L.), navel orangeworm, Amyelois transitella (Walker), and the major postharvest pest Indianmeal moth, Plodia interpunctella (Hübner), were investigated. Both proteins were toxic to the three species tested. Indianmeal moth larvae were the most susceptible and navel orangeworm the least; CryIA(b) was generally more toxic to navel orangeworm. Similar relationships resulted when ICPFs were incorporated into the diet. Both ICPFs caused decreased rate of development of navel orangeworm. Effects on pupal weight occurred only at the highest concentration (100 ng/cm²). Neither ICPF affected frequency of mating or fecundity. In addition to the lethal effects, the extended development times observed could have considerable effects on the population dynamics of the navel orangeworm and possibly other species.     

Brain corticosteroid receptor gene expression and neuroendocrine dynamics during aging

The present study examined the stress responsiveness of the hypothalamic-pituitary-adrenal axis in relation to the properties of corticosteroid receptors in the brain and pituitary in old (30 months) and young (3 months) male Brown Norway rats. The data demonstrate that circulating ACTH rather than the corticosteroid plasma level was elevated under basal conditions and following stress. Furthermore, a reduction of mineralocorticoid receptor (MR) number in the hippocampus and of glucocorticoid receptor (GR) number in the hypothalamus and the pituitary correspond to increased neuroendocrine responsiveness and negative feedback following stress. The changes in receptor binding do not parallel the changes in the amount of MR and GR mRNA measured with in situ hybridization. This suggests that the processing rather than the receptor gene expression is affected in senescence.     

Immunohistochemical demonstration of villin in the normal human pancreas and in chronic pancreatitis

Human pancreatic tissue was investigated by immunohistochemistry using a polyclonal antibody against the actin binding protein villin, which participates in the formation of actin filament bundles in the microvilli. In cells of the different parts of the pancreatic duct system as well as in the acinar cells villin immunoreactivity was located mainly at the apical cell surface. This was confirmed by the ultrastructural demonstration of microvilli on the surface of duct and acinar cells, which exhibited the typical actin bundles. In chronic pancreatitis the staining for villin in duct-like structures of degenerative pancreatic tissue was irregular or even absent. This correlated with the electron microscopic observation of duct-like structures known as tubular complexes composed of cells devoid of microvilli at the apical cell surface. At the light microscopical level degenerative structures without lumen and of unknown origin showed a strong staining for villin at their basal cell surface.     

Interactions among cytochromes P-450 in the endoplasmic reticulum. Detection of chemically cross-linked complexes with monoclonal antibodies

The quaternary structure of rat liver cytochrome P-450 within microsomal membranes from 3-methyl-cholanthrene-treated rats was examined by a novel chemical cross-linking-monoclonal antibody approach. Complex formation among the different forms of P-450 was probed by cross-linking of membrane proteins followed by immunopurification with a monoclonal antibody (mAb) to P-450c, the major 3-methylcholanthrene-inducible form. Subsequent immunoblot analysis of the immunopurified proteins with this mAb indicated that P-450c formed complexes with other microsomal proteins. Immunoblots with mAbs to different P-450s were carried out to identify the P-450s that were cross-linked to P-450c. This approach detected specific cross-linking of P-450c to P-450 2a. Immunoinhibition experiments suggest that P-450 2a further metabolizes the primary phenols produced by P-450c-catalyzed hydroxylation of benzo[a]pyrene. Complex formation among membrane-bound enzymes has implications for their catalytic efficiency and an approach combining cross-linking and monoclonal antibody-based characterization of cross-linked proteins will be useful for elucidating such membrane protein macrostructures.