Freemartinism among singleton bovine females born from multiple embryo transfer

Heterosexual chimerism among singleton females produced by multiple nonsexed embryo transfer (MNET singleton females) was investigated using chromosome typing and PCR (polymerase chain reaction)-amplification of male-specific DNA (msDNA). Of the 22 animals tested, 21 were classified as normal by both methods (i.e., showing no male cells among 100 metaphase spreads in chromosome typing and being msDNA negative in PCR). No morphological abnormalities of the genital organs were observed among 19 MNET single females. One MNET singleton female was, however, classified as a freemartin by PCR (male-specific DNA positive), but it was classified as normal cytogenetically. This individual probably had a low degree of heterosexual chimerism, and it seems that the chimerism derived from MNET was difficult to diagnose by chromosome typing, although it was detectable by PCR. The genital organs of this individual (15-mo-old Aberdeen Angus) were normal in form (both external and internal) and size. However, a very small structure, resembling seminiferous tubule, was found in the left ovary. It may be concluded that most MNET singleton females are expected to have normal reproductive function.     

The centric region of the X chromosome rDNA functions in male meiotic pairing in Drosophila melanogaster

In Drosophila melanogaster males, sex chromosome pairing at meiosis is ensured by so-called pairing site(s) located discretely in the centric heterochromatin. The property of the pairing sites is not well understood. Recently, an hypothesis has been proposed that 240 bp repeats in the nontranscribed spacer region of rDNA function as the pairing sites in male meiosis. However, considerable cytogenetic evidence exists that is contrary to this hypothesis. Hence, the question is whether the chromosomal rDNA clusters, in which a high copy number of 240 bp repeats exists, are involved in the pairing. In order to resolve the problem we X-rayed Drosophila carrying the X chromosome inversion In(1)sc ^V2L sc ^8R and generated free, mini-X chromosomes carrying a substantial amount of rDNA. We defined cytogenetically the size of the mini-chromosomes and studied their meiotic behavior. Our results demonstrate that the heterochromatin at the distal end of the inversion, whose length is approximately 0.4 times that of the fourth chromosome, includes a meiotic pairing site in the male. We discuss the cytological location of the pairing site and the possible role of rDNA in meiotic pairing.     

Microwave treatment of cellulosic materials for their enzymatic hydrolysis

Summary Rice straw and bagasse with water content 84 or 94% were irradiated with microwave (2450MHz) in sealed glass vessels. This treatment enhanced markedly the accessibility of the cellulosic materials for the enzymatic hydrolysis: for example, 1.6 times in the rice straw by the microwave treatment at 170 °C for 5 min and 3.2 times in the bagasse by the treatment at 200 °C for 5 min, compared with the untreated.     

Biological activities of analogues of lipid A based chemically on the revised structural model. Comparison of mediator-inducing, immunomodulating and endotoxic activities

Lipid A analogues were chemically synthesized based on the model structure recently revised, and biological activities of the analogues were tested. The analogue, (beta-1,6)-linked glucosamine disaccharide carrying ester-bound 3-hydroxytetradecanoic acids at 3 and 3' position of reducing and nonreducing glucosamine in addition to amide-bound 3-hydroxytetradecanoic acids and glycosidic-linked and ester-linked phosphate groups, showed much stronger activities for mediator inducing and immunomodulating as well as endotoxic activities than those exhibited by the previously synthesized analogues based on the old model. Among the activities tested, induction of interferon and tumor necrosis factor as well as mitogenicity, adjuvanticity and pyrogenicity were, however, not expressed so strongly as natural lipid A used as controls. In contrast, the analogue exhibited comparable activities to those of control lipid A in the test of lethal toxicity to mice and gelating activity of Limulus amebocyte lysate. Other synthetic analogues carrying a phosphate group showed comparable, slightly stronger or weaker activities depending on the test, but nonphosphorylated analogue exhibited no apparent or only very weak activities.     

Tight association of DNA polymerase alpha with granular structures in the nuclear matrix of chick embryo cell: immunocytochemical detection with monoclonal antibody against DNA polymerase alpha

Immunofluorescent methods using a monoclonal antibody against chick DNA polymerase alpha and a rabbit antibody against chick DNA polymerase beta demonstrated that both DNA polymerases alpha and beta are present mainly in nuclei of cultured chick embryo cells. Fluorescence produced by anti-DNA polymerase alpha was more intense in the small granules than in other parts of the nucleus but, fluorescence produced by anti-DNA polymerase beta was distributed evenly in the nucleus. Cells first were treated with Nonidet P-40, followed by treatment with 50 micrograms/ml pancreatic DNase and 2 M NaCl in order to prepare the nuclear matrix. Fluorescence produced by anti-DNA polymerase alpha was still detectable in the granules after these treatments, but most of the fluorescence produced by anti-DNA polymerase beta disappeared. Our results indicate that a part of DNA polymerase alpha is tightly bound to a special structure present in the nuclear matrix which presumably is the DNA replication machinery.     

Detection and characterization of idiotype-specific enhancing cells generated in mice immunized with idiotype

Cellular interaction between MOPC-104E (M104E) cross-reactive idiotypic (CRI) antibody-producing B lymphocytes and lymphocytes generated by immunization with the relevant idiotype, M104E, was investigated. Adoptive transfer of M104E idiotype-primed and normal spleen cells into 600R x-irradiated syngeneic recipient mice resulted in striking enhancement of the M104E-CRI positive antibody response upon simultaneous immunization of recipients with dextran B1355S. The enhancement was not attributable to a simple additive effect but was due to synergistic cooperation between the two lymphocyte populations. This synergistic enhancement of the anti-idiotype immune cells producing CRI antibody was specific for MOPC-104E CRI, and was reproducible in an in vitro culture system. Because of the cellular characteristics of the enhancing cells, they were assumed to be B lymphocytes specific for the corresponding idiotype, since the activity was not abrogated by treatment with anti-Thy-1, anti-Lyt-1, anti-Lyt-2, or anti-brain-associated theta antisera plus complement, but was eliminated by means of a planning method using a rabbit-anti-mouse immunoglobulin-coated or idiotype-coated dish. The mechanisms of interaction between the CRI-positive B cells and anti-idiotypic B cells in response to the thymus-independent antigen dextran B1355S are discussed.