Aspartic acid residues at positions 190 and 192 of rat DNA polymerase beta are involved in primer binding

The sequence Gly-Asp-Met-Asp, spanning positions 189-192 of rat DNA polymerase beta, is similar to the sequence motif Gly-Asp-Thr-Asp that is highly conserved in a number of replicative DNA polymerases from eukaryotic cells, viruses, and phages. The role of this sequence in the catalytic function of rat DNA polymerase beta was investigated by individually changing each amino acid in this region by site-directed mutagenesis. The mutant enzymes DE190 and DE192, in which aspartic acid residues at positions 190 and 192, respectively, were replaced by glutamic acid, showed about 0.1% activity of the wild-type enzyme. On the other hand, the replacement of Gly-189 by alanine or Met-191 by isoleucine or threonine only slightly affected the enzyme activity. A gel mobility shift assay showed that DNA complexes with enzyme DE190 and especially with DE192 were less stable than the corresponding complex with the wild-type enzyme. Kinetic analysis with these mutant enzymes indicate that their Km's for primer DNA were about 10-fold higher than that of the wild type, while Km's for deoxyribonucleoside triphosphate were not changed. Since neither DE190 nor DE192 had any significant alteration in secondary structure, our results suggest that both Asp-190 and Asp-192 are located in the active site and are involved in the interaction of DNA polymerase beta with primer.     

Effect of the Argentine ant on the specialist myrmecophilous cricket Myrmecophilus kubotai in western Japan

Effects of the Argentine ant on myrmecophilous animals living inside ant nests have been rarely studied to date. We investigated whether the “specialist” myrmecophilous cricket Myrmecophilus kubotai Maruyama that lives only in colonies of a Japanese native ant, Tetramorium tsushimae Emery, could live with the Argentine ant. In the field, the cricket was never found in nests of the Argentine ant. Our experiments showed that the cricket could not survive in artifical nests of the Argentine ant under laboratory conditions.     

Discovery of independent‐founding solitary queens in the yellow crazy ant Anoplolepis gracilipes in East Java,Indonesia (Hymenoptera: Formicidae)

We collected four solitary queens of the invasive ant Anoplolepis gracilipes under stones in East Java, Indonesia. They produced nanitic workers by claustral colony foundation. This is the first report of independent colony foundation by queens in this species. The discovery may give an important insight into discussion on the origin of this invasive ant.     

Chemoimmunotherapy with cyclophosphamide and bestatin in experimental metastasis in mice

Summary Bestatin has significant therapeutic activity (even following oral administration) for the treatment of metastatic disease, an activity which is limited by tumor burden. Therefore, the therapeutic potential of bestatin was examined in combination with chemotherapy to determine if there is additive activity for heavy tumor burdens. Bestatin significantly increased therapeutic activity and decreased the myelotoxicity of cyclophosphamide following a single injection of cyclophosphamide or split daily doses. In immune function studies, in tumor-bearing antimals, bestatin increased the number of colony-forming units (granulocyte-macrophage) (CFU) and alveolar macrophage tumoricidal activity. However, when bestatin was combined with cyclophosphamide, which depressed bone marrow and macrophage activity, it did not show apparent augmentation of macrophage and NK cell activity, but did significantly increase bone marrow CFU activity. Thus, in combined chemoimmunotherapy, bestatin appears to enhance therapeutic activity by accelerating the recovery of hematopoiesis. We suggest, therefore, that a combination chemotherapy protocol, with oral bestatin, may facilitate myelorestoration following aggressive chemotherapy. The majority of biological response modifiers require parental administration; thus, the identification of an orally active, synthetic immunoaugmenting agent with a defined receptor is of particular interest.This research was sponsored by the National Cancer Institute, DHHS, under contract no. N01-23910 with Program Resources Inc. The contents of this publication do not necessarily reflect the views or policies of the Department of Health and Human Services, nor does mention of trade names, commercial products, or organizations imply endorsement by the U.S. Government.     

Effects of bestatin on myelopoietic stem cells in normal and cyclophosphamide-treated mice

Summary The effect of bestatin on hematopoietic parameters and bone marrow progenitor activity (colony-forming unit — granulocyte/macrophage: CFU-GM) was examined in normal and myelosuppressed C₅₇BL/6 mice. CFU-GM frequency and absolute number were determined with a limiting dilution analysis of bone marrow cells in soft agar using recombinant murine colony-stimulating factor — granulocyte/macrophage. We report that bestatin increased splenic, bone marrow, and peripheral blood cellularity and the number of CFU-GM over a dose range from 2.5 mg/kg through 100 mg/kg following i.p., i.v., or oral administration. The greatest myeloid stimulation was observed following multiple injections of bestatin. Bestatin also increased the recovery from cyclophosphamide-induced myelodepression as measured by these parameters. The hematopoietic properties of bestatin following oral administration is of potential importance for clinical application.By acceptance of this article, the publisher or recipient acknowledges the right of the U. S. Government to retain a nonexclusive, royalty-free license in and to any copyright covering the article. This research was supported by the DHHS, under contract no. N01-23910 with Program Resources Inc. The contents of this publication do not necessarily reflect the views or policies of the Department of Health and Human Services, nor does mention of trade names, commercial products, or organizations imply endorsement by the U. S. Government.     

Chemical and immunological properties of galactomannans obtained from Histoplasma duboisii,Histoplasma capsulatum,Paracoccidioides brasiliensis and Blasomyces dermatitidis

Serologically active polysaccharide, galactomannan, was isolated from whole cells ofH. capsulatum, H. duboisii, P. brasiliensis andB. dermatitidis, and their chemical structure and immunological properties were described.