Interaction of histones with estrogens. Covalent adduct formation with 16 alpha-hydroxyestrone

Disturbed estrogen metabolism leading to increased 16 alpha-hydroxyestrone (16 alpha-OHE) has been described in patients with systemic lupus erythematosus and mammary carcinoma. Previous studies showed the formation of covalent complexes between 16 alpha-OHE and nonspecific cellular membrane proteins. The present study is concerned with the interaction of 16 alpha-OHE and histones. Covalent adduct formation between 16 alpha-OHE and individual histones was maximal with H1 histone. Other endogenous estrogens such as estrone, estradiol, and estriol did not interact with histones and form covalent adducts, nor did they interfere with the interaction of 16 alpha-OHE with these nuclear proteins. The evidence supports that the adduct formation between 16 alpha-OHE and histones proceeds via a stabilized Schiff base and subsequent rearrangement. This adduct formation which may have in vivo analogues may represent a mechanism for cellular transformation by this estrogen metabolite.     

A Yersinia enterocolitica serotype 0:3 lipopolysaccharide-specific monoclonal antibody reacts more strongly with bacteria cultured at room temperature than those cultured at 37 degrees C

It has been suggested that the O-side chains of the lipopolysaccharide (LPS) of serotype 0:3 strains of Yersinia enterocolitica vary quantitatively and qualitatively depending on whether they are cultured at 37 degrees C or 25 degrees C. It is uncertain whether this affects the expression of the serotype-specific antigens that are probably carried on the LPS. We studied this question with a serotype 0:3-specific monoclonal antibody, 2C1. This monoclonal antibody immunoprecipitated a 39K major protein from detergent-solubilized 125I-labeled Yersinia preparation. However, results of Western blot experiments demonstrated that the antigens reactive with 2C1 were not actually the 39K protein but the O-side chains of the LPS. Significantly, reactivity could be detected whether the bacteria were cultured at room temperature or at 37 degrees C. However, absorption experiments confirmed that there were less accessible antigenic determinants on the 37 degrees C-LPS. The LPS preparations were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and silver staining. These SDS-PAGE profiles showed that less O-side chains were present in the 37 degrees C-LPS. Hence, the most likely explanation for our observation is that the 37 degrees C incubation condition induced a partial smooth to rough transition of the Yersinia LPS with a decrease in the amount of 2C1-reactive antigen.     

Antibodies to the alpha-subunit of insulin receptor from eggs of immunized hens

Simple methods for the generation, purification, and assay of antibodies to the alpha-subunit of insulin receptor from eggs of immunized hens have been described. Chicken antibodies against the alpha-subunit inhibit insulin binding to the receptor and stimulate glucose oxidation as well as autophosphorylation of the beta-subunit. Thus the properties of chicken antibodies are very similar to those of antibodies found in human autoimmune diseases and different from rabbit antibodies obtained against the same antigen.     

Interaction and identification of ubiquinone-binding proteins in ubiquinol-cytochrome c reductase by azido-ubiquinone derivatives

Various azido-ubiquinone derivatives were synthesized and characterized. 3-Azido-2-methyl-5-methoxy-6-(3,7-dimethyloctyl)-1,4-benzoquinone was found to be suitable for the study of specific interaction between ubiquinone (Q) and protein. It was synthesized with high specific radioactivity and used to identify the Q-binding proteins in purified ubiquinol-cytochrome c reductase. This azido-Q derivative showed partial efficiency in restoring activity to the Q- and phospholipids-depleted ubiquinol-cytochrome c reductase in the absence of light. Azido-Q derivative treated samples, however, became completely inactivated upon photolysis, and the inactivation was not reversed by addition of Q derivatives. The redox state of the azido-Q derivative has little effect on the Q-binding affinity. Two protein subunits with Mr = 37,000 and 17,000 were found to be heavily labeled when depleted ubiquinol-cytochrome c reductase was treated with [3H] azido-Q derivative followed by photolysis and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The amount of radioactive labeling of the Mr = 17,000 protein was proportional to the degree of inactivation and affected by the presence of phospholipids. The radioactive labeling of the Mr = 37,000 protein subunit, however, showed no correlation with degree of inactivation and was not affected by phospholipids. Since the radiolabeling at the Mr = 17,000 protein subunit was affected by phospholipids and correlated with the enzymatic activity, this subunit is probably the Q-binding protein in this enzyme complex (QPc). The inhibition of enzymatic activity by n-heptyl-4-hydroxyquinoline-N-oxide was easily reversed by addition of the azido-Q derivative. The distribution of radioactivity among the subunits of ubiquinol-cytochrome c reductase was not affected by the presence of antimycin A, 5-n-undecyl-6-hydroxy-4,7-dioxobenzothiazole or n-heptyl-4-hydroxyquinoline-N-oxide, suggesting that the binding site(s) of these inhibitors are not the Q-binding site.     

Effects of proteinase K on the energy transfer between phycobiliproteins in phycobilisomes

Spectral changes in fluorescence of phycobilisomes (PBS) of A. variabilis treated with proteinase K were studied at room and liquid nitrogen temperature. In control PBS, the relative yield of 77 K fluorescence of F686 was very high, and those of F655 and F666 were low. In PBS treated with proteinase K for less than 1 h, F686 decreased, and F655 and F666 increased. In PBS treated with proteinase K for 2 h, F655 was the main peak of fluorescence emission, F686 was the second peak, the fluorescence emission peak of F666 disappeared. In PBS treated with proteinase K for more than 8 h, F655 showed only one fluorescence emission peak.We suggested that phycobiliporteins in the PBS of A. variabilis constitute an energy transfer chain, shown as follows:{fx91-1}The linkages between APC and APC-B, C-PC and APC, and C-PC and APC-B had different sensitivity towards proteinase K.     

Rigorous conformational analysis of right and left DNA helices and junction between them

On the basis of complete scanning through conformational space of dihedral angles, twelve structural genera were obtained. Subsequent energy minimization within these genera yielded a limited set of duplexes with stacking: right-handed B-form (Wilkins type), B2-form (Watson and Crick type) and left-handed Ll-form (Sasisekharan type) and the new L2-form. In the polymeric DNA only right-handed double-helices are possible, the left-handed helices are forbidden due to poor 1–5 interchain contacts. In contrast, for short fragments the left- and right-handed helicek have practically the same energies providing some physical ground for side-by-side form, which biologically is possible as recombination form and may be as replication form.     

元江干热河谷山地五百年来植被变迁探讨

元江河谷是云南省最干热地区之一,在海拔800—900米以下的山地上广泛分布着稀树灌草丛。根据《元江府志》(1714年编纂)、《元江州志》(1826年编纂)、《元江志稿》(1922年编篡)及对现存植被的考察,本文探讨了元江干热河谷山地五百年来植被的变迁。 元江县森林复盖率的减少与人口的增加有密切关系,十七世纪中期以前,森林复盖率在75％以上,十八、十九世纪时为70％左右,1958年为61.5％,1975年为27.3％,至1982年则为19.3％。研究表明,在十九世纪以前,这个地区分布的主要植被是热带季雨林,甚而热带季节雨林,以后热带稀树灌草丛则迅速发展。植被的历史变化与土壤流失密切相关。植物群落的演变是由以乔木树种为优势演变为以灌木种类为优势,再演变为以多年生草木植物为优势,而最后则成为裸地。本文也讨论了这个地区植被恢复的方法。     

依兰花精油的香气成分

云南省西双版纳产依兰油,用Finnigan-4510型毛细管气相色谱/质谱/计算机联用方法进行了化学成分分析,共分离检出了50个成分,鉴定了其中22个成分,占全精油的95.27％。主要成分为:β-丁香烯(33.00％),γ-穆罗烯(19.82％)。α-(艹律)草烯(7.69％),乙酸香叶酯(6.21％),香柠檬烯(5.40％),苯甲酸苄酯(5.33％),金合欢醇(4.75％),金合欢烯(3.29％),香叶醇(2.48％),对甲酚甲醚(2.41％)。并讨论了如何提高国产依兰油质量的问题。     

Activity of propriospinal neurons in segments C3 and C4 during fictitious locomotion in cats

Activity of propriospinal neurons in segments C3 and C4 was recorded in immobilized decerebrate cats, whose spinal cord was divided at the lower thoracic level, during locomotor activity of neuronal mechanisms controlling the forelimbs (fictitious locomotion of the forelimbs). Neurons were identified according to antidromic responses to stimulation of the lateral column of the spinal cord at level C6. Antidromic responses also appeared in 70% of these neurons to stimulation of the medullary lateral reticular nucleus. During fictitious locomotion, i.e., in the absence of afferent signals from the limb receptors, rhythmic modulation of the discharge of most neurons was observed, correlating with activity of motoneurons. If the rostral region of the cervical enlargement of the spinal cord was cooled, causing generation of the locomotor rhythm to cease, rhythmic activity of propriospinal neurons in segments C3 and C4 also ceased. The main source of modulation of activity of propriospinal neurons in segments C3 and C4 is thus the central spinal mechanisms controlling activity of the forelimbs.Institute for Problems in Information Transmission, Academy of Sciences of the USSR, Moscow. M. V. Lomonosov Moscow University. Translated from Neirofiziologiya, Vol. 17, No. 3, pp. 320–326, May–June, 1985.     

Ganglioside GD3: structure,cellular distribution,and possible function

Summary Insight on the function of gangliosides. can emerge from knowledge of their cellular distribution. In this paper we review the structure of ganglioside G_D3 and recent information on its cellular distribution. G_D3 appears to be enriched in a variety of neural cell types including: reactive glia, gliomas, undifferentiated neurons, Muller glia, and oligodendroglia. Because each of these cell types share an enhanced permeability to ions and metabolites or possess properties associated with enhanced permeability, we suggest that G_D3 is associated with enhanced membrane permeability. A possible function for G_D3 in membrane permeability has implications for other cellular events such as metabolism, growth and interactions.