Genetic mediation of infanticide and parental behavior in male and female domestic and wild stock house mice

Infanticide is a reproductive strategy found in many mammals, especially rodents. The proportion of male and female house mice (Mus domesticus) that are either infanticidal or noninfanticidal is strain specific and varies widely from stock to stock. Male house mice also show strain-specific variation in the behavioral mechanisms that inhibit infanticidal individuals from killing their own offspring. The adult offspring generated from reciprocally crossed CF-1 and Wild stock house mice were tested for their behavior toward newborn pups. In male CF-1xWild hybrids, the proportion of infanticidal and noninfanticidal males matched with their maternal phenotype, whereas female CF-1xWild hybrids exhibited a proportion of behaviors typical of the CF-1 phenotype, regardless of their mother's genotype. Our results suggest three conclusions: first, that infanticide is a highly labile and heritable behavior in both sexes; second, that there is a sex difference in the genetic substrate that regulates the inheritance of infanticidal behavior; and third, that selection pressures in male mice may operate independently on the mechanisms that promote spontaneous infanticidal behavior versus the mechanisms that inhibit infanticide.     

Aberrant chromatin at genes encoding stem cell regulators in human mixed-lineage leukemia

Mixed-lineage leukemia (MLL) fusion proteins are potent inducers of leukemia, but how these proteins generate aberrant gene expression programs is poorly understood. Here we show that the MLL-AF4 fusion protein occupies developmental regulatory genes important for hematopoietic stem cell identity and self-renewal in human leukemia cells. These MLL-AF4-bound regions have grossly altered chromatin structure, with histone modifications catalyzed by trithorax group proteins and DOT1 extending across large domains. Our results define direct targets of the MLL fusion protein, reveal the global role of epigenetic misregulation in leukemia, and identify new targets for therapeutic intervention in cancer.     

Correlation between immunosuppressive activity and translation regulatory activity

An immunoglobulin negative material from the eluate of an anti-idiotype immunosorbent column [1] exhibited potent immunosuppressive activity. This material also inhibited the translation of globin mRNA in a cell-free reticulocyte lysate system. The translation inhibitory activity of this material was not attributable to nucleases which were separable by a blue-dextran agarose column. Further correlation between immunosuppressive activity and translation inhibitory activity was observed when GTP or GTP analogue was included in experimental systems. These results suggest that the immunosuppressive factor (or factors) may contain a translation inhibitory factor. The biochemical mechanism of immunosuppression is discussed.     

Wound infection by Prototheca wickerhamii, a saprophytic alga pathogenic for man.

Biopsy of a wound infection of the palmar fascia in a young diabetic woman revealed characteristic periodic acid-Schiff-positive Prototheca species cells with a rosette configuration and internal septation. Prototheca wickerhamii was cultured repeatedly from the wound drainage and the biopsy tissue. Several diagnostic features distinguishing Prototheca species, saprophytic algae, from yeasts are: the formation of endospores by mitosis; greater variation in cell size (2 to 15 mum); the presence of cytoplasmic granules, particularly in old cultures; and the absence of budding forms and pseudomycelia. The organism was resistant to 5-fluorocytosine and the minimal inhibitory concentration of amphotericin B was 12.5 mug/ml. With the exception of the tetracycline group, all other 16 antibacterial agents tested appeared completely ineffective in vitro. A synergism between amphotericin B and tetracycline was clearly demonstrated by the use of the checkerboard method. Infection by Prototheca species may be more common than presently realized due to the common expedient of identifying yeast-like isolates as "yeast--not Candida albicans."     

Purification and characterization of a 43-kilodalton extracellular serine proteinase from Cryptococcus neoformans

An extracellular proteinase was purified from culture filtrates of Cryptococcus neoformans NHPY24 by DEAE ion-exchange chromatography and gelatin affinity column chromatography with azoalbumin as the substrate. The molecular mass of the purified enzyme was 43 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, its pH optimum was 7.0 to 8.0, and maximal activity was obtained at pH 7.5 and 37 degrees C. By isoelectric focusing, the purified enzyme had a pI of 4.77. Enzyme activity was inhibited by serine proteinase inhibitors such as phenylmethylsulfonyl fluoride and diisopropylfluorophosphate. The purified enzyme was thus a serine proteinase. It hydrolyzed natural substrates including hemoglobin, beta-casein, and gamma globulin.     

Roles of sortase in surface expression of the major protein adhesin P1, saliva-induced aggregation and adherence,and cariogenicity of Streptococcus mutans

Sortase is a newly discovered transpeptidase that covalently links LPXTGX-containing surface proteins to the gram-positive bacterial cell wall. In this study, the sortase gene (srtA) was isolated from Streptococcus mutans NG8 by PCR. The gene encoded a 246-amino-acid protein, including a 40-amino-acid signal peptide. The srtA gene was insertionally inactivated by a tetracycline resistance cassette. P1, a major surface protein adhesin previously shown to anchor to the peptidoglycan by the LPXTGX motif, was secreted into the culture medium by the srtA mutant. In contrast, the wild-type P1 remained cell wall associated. Complementation of the mutant with srtA restored the P1 surface expression phenotype. P1 produced by the mutant, but not that produced by the wild type and the srtA-complemented mutant, was recognized by an antibody raised against the hydrophobic domain and charged tail C terminal to the LPXTGX motif. These results suggest that the failure to anchor P1 to the cell wall is due to the lack of cleavage of P1 at the LPXTGX motif. The srtA mutant was markedly less hydrophobic than the wild type and the complemented mutant. The srtA mutant failed to aggregate in the presence of saliva or salivary agglutinin and adhered poorly to saliva- or salivary agglutinin-coated hydroxylapatite. In rats, the srtA mutant colonized the teeth poorly when sucrose was absent. When sucrose was present, the srtA mutant colonized the teeth but less effectively and induced significantly less caries (P < 0.05) than the wild-type strain. In conclusion, the sortase enzyme in S. mutans is responsible for anchoring P1 to the cell surface and plays a role in modulating the surface properties and cariogenicity of S. mutans.     

Enhancement of cALL immunogenicity by co-culture with a CD154 expressing 293 cell line

Pre-B cell acute lymphoblastic leukaemia (cALL) commonly occurs in young patients and although successful conventional therapies are available (such as cytotoxic drugs and bone marrow transplantation) for a proportion of patients (approximately 30%) these are ultimately unsuccessful. Recurrence of disease is a result of the failure of the immune system to recognize these abnormal cells and down-regulation of crucial molecules required for cognate CD4(+) T cell recognition has been postulated as a means of immune escape. In this study we show that an embryonic kidney cell line (293 cells) transfected with CD154 (40 L.1) are capable of not only maintaining the viability of primary ALL cells in culture but can also up-regulate the expression of a number of crucial molecules involved in antigen recognition. We show that 40 L.1 cell stimulation of primary ALL cell cultures can not only enhance the allogeneic and autologous MLR response to such cells but will also induce CTL effectors which are capable of lysing wild-type autologous ALL cells. It is therefore conceivable that such an approach could be used to generate an active anti-tumour response in patients, following conventional therapy, reducing the incidence of recurrence.     

Human Mannose-Binding Protein Inhibits Infection of HeLa Cells by Chlamydia trachomatis

The role that collectin (mannose-binding protein) may play in the host’s defense against chlamydial infection was investigated. Recombinant human mannose-binding protein was used in the inhibition of cell culture infection by Chlamydia trachomatis (C/TW-3/OT, E/UW-5/Cx, and L₂/434/Bu), Chlamydia pneumoniae (AR-39), and Chlamydia psittaci (6BC). Mannose-binding protein (MBP) inhibited infection of all chlamydial strains by at least 50% at 0.098 μg/ml for TW-3 and UW-5, and at 6.25 μg/ml for 434, AR-39, and 6BC. The ability of MBP to inhibit infection with strain L₂ was not affected by supplementation with complement or addition of an L₂-specific neutralizing monoclonal antibody. Enzyme-linked immunosorbent assay and dot blot analyses showed MBP bound to the surface of the organism to exert inhibition, which appeared to block the attachment of radiolabeled organisms to HeLa cells. Immunoblotting and affinity chromatography indicated that MBP binds to the 40-kDa glycoprotein (the major outer membrane protein) on the outer surface of the chlamydial elementary body. Hapten inhibition assays with monosaccharides and defined oligosaccharides showed that the inhibitory effects of MBP were abrogated by mannose or high-mannose type oligomannose-oligosaccharide. The latter carbohydrate is the ligand of the 40-kDa glycoprotein of C. trachomatis L₂, which is known to mediate attachment, suggesting that the MBP binds to high mannose moieties on the surface of chlamydial organisms. These results suggest that MBP plays a role in first-line host defense against chlamydial infection in humans.     

Modulation of transglutaminase expression in rat skeletal muscle by induction of atrophy and endurance training.

The persistence of muscle fiber number regardless of size reduction in muscle atrophy has not yet been fully explained. For the mechanism inherent in skeletal muscle tissues for preventing cellular death, the protective function of muscle tissue through transglutaminases has been tested, since the enzyme is responsible for structural stabilization and participates in signal transduction. In the present experiment, hindlimb suspension for two weeks caused a marked muscle atrophy in Wistar female rats. Comparison of muscle weight and histological analysis showed that suspension-induced atrophy in the hindlimb was more prominent in the soleus muscle, comprised mainly of type I fiber than that in the plantaris muscle of type II fibers. The immunohistochemical analysis with antitransglutaminase C antibody (anti TGase C Ab) showed that some atrophic bundles of soleus muscle were positively reacted with the antibody. The anti-TGase C Ab-reactive substances were observed to disappear significantly after endurance exercise, indicating their characteristic atrophy-dependency. The enzymatic analysis of transglutaminase showed the increase in activity in the atrophic soleus muscle tissue, compared with that in the normal or exercise-trained muscle tissues. From these results, the expression of TGase in the atrophic muscle is suggested to be the possible marker for muscle atrophy and its expression is probably related with the protective mechanism of the muscle tissue to prevent further cellular damage in the atrophic process.     

Molecular cloning and expression of a Streptococcus mutans major surface protein antigen, P1 (I/II), in Escherichia coli.

Antigen P1, also called I/II, is one of the most abundant cell wall proteins of the mutans streptococci. It has been suggested that P1 may be involved in cell adherence to tooth surfaces and in sucrose-induced cell aggregation. As a first step toward fully understanding its biological functions, the P1 gene, which has been designated spaP1, from Streptococcus mutans NG5 (serotype c) has been cloned into Escherichia coli JM109 by a shotgun procedure with pUC18 as the vector. The recombinant strain expressing P1 carries a 5.2-kilobase DNA insert whose restriction map has been determined. This map is completely different from that of spaA of Streptococcus sobrinus (serotype g), even though P1 and SpaA are antigenically related. Southern hybridization revealed that DNA sequences closely homologous to spaP1 were present in serotypes c, e, and f, and similar sequences also existed in strains of serotypes a and d. The expression of the cloned spaP1 was found to be independent of the lac inducer and the orientation of the DNA insert, suggesting that it carries its own promoter. Western blotting (immunoblotting) revealed at least 20 bands reacting with a mixture of three anti-P1 monoclonal antibodies. The highest-molecular-weight reactive band was comparable in size to the parent P1 (185 kilodaltons [kDa]); however, the major reactive bands were smaller (approximately 160 kDa). Expression of cloned P1 in E. coli LC137 (htpR lonR9) resulted in the increased prominence of the 185-kDa protein reactive band. Ouchterlony immunodiffusion showed partial identity between the parent and cloned P1. In E. coli, P1 was detected primarily in the periplasm and extracellular fluid.