The amino acid sequence of a major protein component in the light harvesting complex of the green photosynthetic bacterium Chlorobium limicola f. thiosulfatophilum

A 7.5-kDa protein has been isolated from chlorosomes of Chlorobium limicola f. thiosulfatophilum and the complete primary structure determined by a combination of automatic Edman degradation and plasma desorption mass spectrometry. The 74-residue protein shows great homology to a similar protein of unknown function which has been isolated from Pelodictyon luteolum but otherwise no significant homology to other proteins can be found. The possible role of the protein in the structure and function of the chlorosome is discussed.     

The antigenic characteristics of the capsid proteins in strains of the potato virus Y]

The antigenic properties of capsid proteins of potato virus Y (PVY) strains have been studied, the most wide antigenic specificity of necrotic group strains has been marked. Several antigen-active strains of necrotic group strains (PVY-N Far East, PVY-N Leningrad, PVY-N Moscow) and common group (PVY-O-3 Moscow, PVY-O Far East) have been revealed. Antisera against these strains reacted with any PVY strain. Virus specific surface epitope, corresponding to position 198-208 of polypeptide chain has been located, which is a group-specific epitope of potyviruses, identified in the Far East.     

Extrachromosomal human immunodeficiency virus type-1 DNA can initiate a spreading infection of HL-60 cells

In this report, we describe a human immunodeficiency virus type-1 (HIV-1)-infected promyelocytic cell line, OM, derived from HL-60 cells. Although the OM cell line was biologically cloned twice, the pattern of HIV-1 expression during culture appeared analogous to a classical acute spreading infection and was inhibited by both azidothymidine and recombinant soluble CD4 treatment. The number of OM cells actually expressing HIV-1 at the beginning of culture was 0%, reached a peak of nearly 100% at 6 weeks, and then fell to less than 10% HIV-1+ cells by 10 weeks. Clonal analysis of the surviving cells verified that stable HIV-1+ OM cells resulted from the spreading infection. Southern analysis confirmed the transmission of HIV-1 through these OM cultures and the occurrence of stable clones which resulted. The initial percentage of OM cells actually harboring the HIV-1 genome was less than 0.1%, indicating nonfaithful transmission of an unintegrated HIV-1 genome during clonal expansion. These results demonstrate that extrachromosomal HIV-1 DNA can contribute to the spread of HIV-1 infection and give rise to cells which have stably integrated HIV-1 provirus.     

Mechanism of melatonin action

Melatonin transduces the effect of photoperiod on the neuroendocrine system. Synthesis of melatonin in the pineal gland is well described, but the location of its target(s) and the mechanism of its action are little known. In attempt to localize melatonin target(s), the presence of high affinity binding sites in rat brain was determined. Such sites were detected in discrete brain areas, including the hypothalamus and anterior pituitary. Subcellular analysis indicated these binding sites were on plasma membranes, which suggests that melatonin modulates cell functions through intracellular second messengers. The effects of melatonin on second messengers were studied using the neonatal anterior pituitary, in which melatonin is known to inhibit the LHRH-induced release of LH. Studies on the effects of melatonin on second messenger indicated [corrected] that melatonin inhibits accumulation of cAMP and cGMP as well as synthesis of diacylglycerol and release of arachidonic acid. Time-course analysis indicates that inhibition by melatonin of the LHRH-induced release of LH increases following long preincubation. Since the effect of melatonin on LHRH-induced release of LH is prevented by dibutyryl cAMP, we conclude that melatonin might act by inhibiting production of cAMP.     

Neutrophils-induced increase of adenosine triphosphate depletion in rat neonatal cardiac myocytes with impaired energy metabolism.

Isolated, cultured rat neonatal cardiac myocytes were placed in medium supplemented with mitochondrial respiratory inhibitor potassium cyanide which caused a rapid adenosine triphosphate (ATP) depletion. These myocytes with the impaired energy metabolism ("hypoxia-like state") were exposed to unstimulated human neutrophils. Effect of human neutrophils on the myocytes in the "hypoxia-like state" was quantified as a total change in the amount of ATP in cardiac cells. After 5 hours of incubation of neutrophils with the myocytes in the "hypoxia-like state" an additional decrease (of 50 per cent) in ATP content was observed. Since catalase (which destroys hydrogen peroxide) prevented the further decline in ATP level in the myocytes with impaired energy metabolism, it seem that hydrogen peroxide and possibly their products are responsible for this effect. These results suggest that unstimulated human neutrophils after activation by the contact with injured cardiac cells caused further decrease of ATP level in target cells.     

Whole blood superoxide anion generation and efficiency of some erythrocyte antioxidant systems during recombinant human erythropoietin therapy of uremic anemia

Six chronic uremic patients on regular hemodialysis treatment were given recombinant human erythropoietin (r-huEPO) in a dose of 50 U/kg of body weight intravenously thrice weekly for 14 weeks. Following r-huEPO therapy, unstimulated whole blood superoxide anion ( ₂) generation did not change significantly, while opsonized zymosan-stimulated whole blood ₂ generation increased. At the same time, erythrocyte superoxide dismutase and, in particular, glutathione peroxidase activities were found to be reducing with concomitant lowering of erythrocyte malonydialdehyde (MDA) concentrations and increase in plasma MDA concentrations.     

Bone morphogenetic protein 4 (BMP-4), a member of the TGF-beta family, in early embryos of Xenopus laevis: analysis of mesoderm inducing activity

We have screened a Xenopus ovary cDNA library using a synthetic oligonucleotide derived from that part of the inhibin beta A sequence, which is highly conserved within the TGF-beta family. Out of several clones yielding autoradiographic signals four turned out to represent Xenopus counterparts to the human bone morphogenetic protein 4 (BMP-4). Each two of the four sequences are nearly identical and probably account for different alleles whereas the two pairs showing 5% divergence may have arisen by genome duplication in this tetraploid species. The amino acid sequence of the Xenopus protein is 80% homologous to the human sequence showing no single exchange within the last 100 amino acids at the C-terminus. This region, which constitutes the main part of the mature, biologically active protein, also exhibits substantial homologies to other representatives of the TGF-beta family, especially to the Drosophila DPPC protein. Transfection of COS-1 cells with the Xenopus BMP-4 sequence under control of the CMV-promoter leads to the secretion of a protein which exhibits mesoderm inducing activity when tested with animal cap explants from Xenopus blastula stage embryos.     

Biodegradation of toxic and environmental pollutants.

Organic chemicals that are toxic to humans and to the environment can be transformed and metabolized by a variety of microorganisms. Such chemicals include trichloroethylene, chloroform, carbon tetrachloride, toluene, phenols, chlorinated phenols, polychlorinated biphenyls and polyaromatic hydrocarbons. This review focuses on some of the most important recent developments in the biodegradation of these toxic chemicals. Depending on the compound and the organism, the extent of our understanding ranges from the molecular level to the conceptual.     

Comparison of an electrochemiluminescent homogenous immunoassay and an ELISA for monitoring productivity in mammalian cell bioreactors

Summary An Enzyme Linked Immuno Sorbent Assays (ELISA) and an Electro-chemiluminescent Immuno Assay (CIA) are compared for the purpose of monitoring product formation in mammalian cell bioreactors. The ELISA had a relative standard deviation of 10%, compared to 8% for the CIA . The CIA was found to be a fast and accurate alternative to the ELISA. The use of more than one immuno assay format was also shown to provide additional insight into process performance.