Aerobic mineralization of vinyl chloride by a bacterium of the order Actinomycetales

A gram-positive branched bacterium isolated from a trichloroethylene-degrading consortium mineralized vinyl chloride in growing cultures and cell suspensions. Greater than 67% of the [1,2-14C]vinyl chloride was mineralized to carbon dioxide, with approximately 10% of the radioactivity appearing in cell biomass and another 10% appearing in 14C-aqueous-phase products.     

Structure and function of tyrosine kinase receptors

Over the past ten years, several growth factor receptors have been shown to be ligand-regulated tyrosine kinases. Tyrosine kinase activity is essential for signal transmission, suggesting that phosphorylation cascades may play an important role. Considerable effort has gone into understanding the structure and function of tyrosine kinase receptors in order to define their mechanisms of signal transmission. However, the protein substrates of the receptor kinases have proven to be difficult to isolate and clone. This review focuses on the receptors for insulin, epidermal growth factor, and platelet-derived growth factor. They are all tyrosine kinases, but emerging evidence suggests that they utilize multiple separate signal transduction pathways. Work carried out during the next several years should yield considerable insight into the complexity of the components which interact with these tyrosine kinase receptors to regulate cellular growth and metabolism.     

Murine erythrocyte ankyrin cDNA: highly conserved regions of the regulatory domain

Ankyrin is an essential link between cytoskeletal proteins, such as spectrin, and membrane bound proteins, such as protein 3, the erythrocyte anion exchanger. Although the amino acid structure of human ankyrin is known, the functional regions have been only partially defined. Sequence comparisons between mouse and human ankyrin offer one mechanism of identifying highly conserved regions that probably have functional significance. We report the isolation and sequencing of a series of overlapping murine erythroid ankyrin (Ank-1) cDNAs from spleen and reticulocyte libraries (total span 6238 bp) and identify potentially important regions of murine-human reticulocyte ankyrin homology. Comparison of the predicted peptide sequences of mouse and human erythroid ankyrins shows that these ankyrins are highly conserved in both the N-terminal, protein 3 binding domain (96% amino acid identity) and in the central spectrin-binding domain (97% identity), but differ in the C-terminal regulatory domain (79% identity). However, the C-terminal regulatory domain contains two regions of peptide sequence that are perfectly conserved. We postulate these regions are important in the regulatory functions of this domain.     

Oestrogen receptor gene structure and function in breast cancer

The mechanisms underlying loss of oestrogen responsiveness in breast cancer are not well-defined. Potential mechanisms include loss of receptor expression, alterations in the oestrogen receptor (ER) gene producing proteins with abnormal function, or changes to receptor-dependent or -independent pathways controlling cell proliferation. Examination by Southern analysis of the ER gene in a series of ER-negative and -positive breast tumour biopsies failed to provide evidence of gross rearrangements and in only only one of thirty seven tumour DNA samples was significant gene amplification observed. No restriction fragment length polymorphisms were detected for the restriction enzymes EcoRI, Pst I or Hind III. Methylation of the ER gene as assessed by Hpa II and Msp I restriction enzyme digests varied between tumours but the degree of methylation was not correlated with levels of expression of the receptor protein. Similar findings applied in a series of ER-negative and -positive breast cancer cell lines and clonal lines of MCF-7 cells, which were developed as an in vitro model for the acquisition of oestrogen and antioestrogen resistance. In this model there was no evidence that changes to ER receptor function and/or structure at the level of the ER gene, mRNA, ligand binding, and ability to induce progesterone receptor might account for the development of hormone resistance. However, the ability of ER to interact with a DNA sequence containing the vitellogenin promoter oestrogen response element, as assessed by gel retardation assay, was impaired in the clone showing the greatest degree of oestrogen and antioestrogen resistance.     

The acetycholinesterase gene ofAnopheles stephensi

1. The acetylcholinesterase (AChE) gene from the important malaria vector Anopheles stephensi has been isolated by homology to the Drosophila acetylcholinesterase gene. 2. The complete sequence and intron-exon organization has been determined. The encoded protein has 69% identity to Drosophila AChE and 38 and 36% identity to Torpedo AChE and human butyrylcholinesterase, respectively.     

Expression of two cytochromes P450 involved in carcinogen activation in a human colon cell line

Cytochrome P450 is known to cause carcinogen activation and correspondingly increased cancer risk in animal models. In order to determine whether P450 in the colon may be involved in cancer development in the human, the human colon cell line LS174T was examined for the presence of various cytochromes P450. Two isozymes of P450 were identified in the human cell line. Expression of P450IAl or IA2 was increased by treatment of the cell line with benzanthracene; the induction was demonstrated by an increase in RNA hybridizing to a probe for P4501Al and by ethoxyresorufin deethylation activity. Western analysis of microsomes isolated from human colon tissue also demonstrated the presence of P4501A1, as well as a form which cross-reacted to an antibody to human P450IIC9. Another isozyme, P450IIE1, was identified by polymerase chain reaction amplification of RNA from LS174T cells. These results underscore the presence of cytochromes P450 in colonic tissue and provide a basis for the involvement of isozyme-specific P450 mediated reactions in carcinogenesis of the colon.Some of the data presented here were taken from a thesis submitted by D.K.H. in partial fulfillment of the requirements for the Ph.D. degree in the University of Texas Graduate School of Biomedical Sciences.     

Mapping of the MYC gene to band 8q24.12----q24.13 by R-banding and distal to fra(8)(q24.11), FRA8E, by fluorescence in situ hybridization

The MYC gene was mapped to R-banded human prometaphase chromosomes and to chromosomes expressing fra(8)(q24.11) by fluorescence in situ hybridization. By high-resolution banding analysis, the fluorescent signals were localized to R-positive band q24.12----q24.13 of the long arm of chromosome 8. Furthermore, the signals were localized near the middle part, q24.12----q24.13, of the distal portion of fra(8)(q24.11) expression. Thus, the precise localization of MYC was to the subband 8q24.12----q24.13.     

The platelet open canalicular system: a final common pathway.

Channels of the surface-connected, open canalicular system (OCS) of human platelets serve as the pathway for transport of substances into the cells and as conduits for the discharge of alpha granule products secreted during the platelet release reaction. The purpose of the present study was to determine if both functions of the OCS can take place simultaneously. Suspensions of washed platelets were exposed to thrombin at 1 U/ml for 5, 60, or 180 seconds in the presence of fibrinogen molecules coupled to particles of colloidal gold (Fgn/Au). The samples were fixed in a low concentration of glutaraldehyde and embedded in L.R. White resin to preserve antigenicity. Thin sections were exposed to a rabbit polyclonal antibody to human fibrinogen followed by an anti-rabbit IgG coupled to 5-nm gold beads. Thrombin caused Fgn/Au particles to bind to platelets and enter channels of the surface-connected OCS. Endogenous fibrinogen detected by immunogold 5-nm beads were localized to alpha granules in resting platelets and 5 seconds after thrombin stimulation. At 60 seconds and 3 minutes Fgn/Au particles were present in swollen alpha granules, as well as OCS channels. Fibrinogen gold beads were evident in alpha granules and OCS channels connected to the platelet surface. The 18- to 20-nm Fgn/Au particles were in the same channels of the OCS as fibrinogen gold beads. The OCS is a final common pathway for uptake of particulates and discharge of secretory products in thrombin-activated human platelets.     

Lymphocyte activation and serine-esterase induction following recombinant interleukin-2 infusion for lymphomas and acute leukaemias

Summary C57BL mice inoculated with radiation leukemia virus (RadLV) develop preleukemic cells long before the onset of leukemia. These cells are potentially immunogenic but fail to elicit an immune response in the host because of the appearance of virus-specific suppressor T cells. We have studied the effect of polysaccharide K (PSK) on the generation of RadLV-specific cell-mediated immune responses in vitro. Long-term exposure to PSK in culture potentiated the ability of immunized T cells to respond to a RadLV-induced lymphoma. It also abrogated the suppressive activity of suppressor T cells and simultaneously boosted the ability of reactive T cells to respond. The dual immunostimulating activity of PSK resulted in the generation of T cytotoxic lymphocytes that could lyse lymphoma cells in vitro. The results suggest that PSK could be used as a prophylactic immune response modifier in preleukemia.