Chromosomes of Temnocephala minor,an ectosymbiotic turbellarian on Australian crayfish found in Kagoshima Prefecture,with karyological notes on exotic turbellarians found in Japan

Records of exotic turbellarian species found in Japan are reviewed from taxonomic and karyological viewpoints. Temnocephala minor Haswell, 1888, an ectocommensal on a freshwater crayfish of Australia, was found from culture ponds of Cherax tenuimanus (introduced from W. Australia) in Kagoshima Prefecture. T. minor had the chromosome number of 2x = 18 (2sm + 2m + 2m + 2sm + 2m + 2m + 2m + 2sm + 2m). The following 3 species of exotic freshwater triclads were recorded from tanks and ponds used for tropical fish culture: Dugesia austroasiatica Kawakatsu, 1985 (2x = 16), Dugesia tigrina (Girard, 1850) (2x = 16) and Rhodax? sp. (3x = 24; 3x = 24 &; 3x + 1LB + 1SB = 25 + 1SB). The following 3 species of exotic terrestrial triclads were recorded: Bipalium nobile Kawakatsu et Makino, 1982 (2x = 10), Bipalium kewense Moseley, 1878 (2x = 18), and Platydemus manokwari de Beauchamp, 1962 (n = 6, 2x = 12). An extensive occurrence of P. manokwari in the Southwest Islands of Japan may be due to an unexpected introduction of the animal in very recent years.     

Carcinogenesis in accessory sex organs of rats induced by 3,2′-dimethyl-4-aminobiphenyl: response to androgen deprivation

 It is generally accepted that early human prostate cancers reveal higher androgen dependency than do advanced ones. In the present study, we examined whether the animal model of prostate cancer has already lost androgen dependency at the early stages of carcinogenesis. At experimental week 46, androgen deprivation was induced in rats and the incidences of atypical hyperplasia and cancer were examined in the ventral, dorsolateral prostate, coagulating glands, and seminal vesicles. Androgen deprivation significantly lowered the incidence of atypical hyperplasia in all four organs. As for the incidence of cancer, no significant differences were observed in the coagulating glands and seminal vesicles. Regarding atypical hyperplasia, androgen deprivation significantly decreased the proliferative cell nuclear antigen labeling index in the coagulating gland and seminal vesicles. The presence of cancer was also decreased in the coagulating gland but not in the seminal vesicles. With control group specimens, more intense staining of androgen receptor was observed in atypical hyperplasias than in cancers. Compared with the atypical hyperplasias, the cancers revealed low androgen dependency at the early stages of carcinogenesis. The cancers in the seminal vesicles also revealed higher androgen independency than did those in the coagulating gland. Accepted: 6 May 1997     

A stereocontrolled synthetic approach to glycopeptides corresponding to the carbohydrate-protein linkage region of cell-surface proteoglycans

The glycopeptides 1

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and 2

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), carrying the core structure of serine-linked cell-surface proteoglycans were synthesized in a stereocontrolled manner. The carbohydrate key imidate xylosyl donors 3 and glycotetraosyl donors 4 and 5, as well as a tetrapeptide glycosyl acceptor 6, were coupled in the crucial glycosylation step. In these reactions, the application of either trimethylsilyl trifluoromethanesulfonate (TMSOTf) or borontrifluoride etherate (BF₃-Et₂O) as catalysts proved to be highly efficient. The serine linked glycopeptides 34, 36 and 37 thus obtained yielded target compounds 1 and 2 on complete deprotection.     

Synthetic inhibitors of trypsin, plasmin, kallikrein, thrombin, C1r-, and C1 esterase.

p-Carbethoxyphenyl episol-guanidinocaproate and p-(p'-guanidinobenzoyloxy)-phenyl derivatives were prepared, and their inhibitory effects on trypsin, plasmin, plasma kallikrein, thrombin, C1r- and C1 esterase were examined. Among the various inhibitors tested, p-nitrophenyl p'-guanidinobenzoate, N,N-dimethylamino p-(p'-guanidinobenzoyloxy)-benzoyl glycolate and N,N-dimethylamino p-(p'-guanidinobenzoyloxy)-benzilcarbonyloxy glycolate were the most effective inhibitors of trypsin, plasmin, plasma kallikrien and thrombin, and they strongly inhibited the esterolytic activities of C1r- and C1 esterase.     

Formation of porphyrin pi cation radical in zinc-substituted horseradish peroxidase

Zinc-substituted horseradish peroxidase is oxidized by K2IrCl6 to a characteristic state which retains one oxidizing equivalent more than the zinc peroxidase. The oxidized enzyme gives an optical absorption spectrum similar to that of compound I of peroxidase and catalase, and a g = 2 electron paramagnetic resonance signal which has an intensity corresponding to the porphyrin content. It is reduced back to the zinc peroxidase by a stoichiometric amount of ferrocyanide or by a large excess of K3IrCl6. From the equilibrium data, the value of E0' for the zinc peroxidase couple is estimated to be 0.74 V at pH 6. The oxidized zinc peroxidase is also formed by the addition of H2O2 or upon illumination with white light. The rate constants for the oxidation by K2IrCl6 and H2O2 at pH 8.0 are 8 x 10(5) and 8 x 10(2) M-1 s-1, respectively. No essential spectral change can be observed when K2IrCl6 is added to the metal-free peroxidase (protoporphyrin--apoperoxidase complex) or to zinc-substituted sperm whale myoglobin.     

Effects of 2 water-soluble contrast media, meglumine iothalamate (Conray) and meglumine iocarmate (Dimer-X), on the electric activity of identifiable giant neurons of the African giant snail (Achatina fulica Ferussac)]

The influences of two water soluble contrast media, meglumine iothalamate and meglumine iocarmate, on the neuronal excitability and on the neuronal sensitivity to putative transmitters were examined in comparison with those of sucrose using two identifiable giant neurones of Achatina fulica Férussac (the TAN and the PON). A relatively low increase of osmotic pressure of the extracellular fluid, produced by the application of contrast media, reversed the Cl- dependent inhibition caused by a putative transmitter. The same increase of this osmotic pressure, however, did not influence the Cl- independent inhibition and the excitation of the neurone examined. The hyperpolarization of neuromembrane was caused by an increase of osmotic pressure of the extracellular fluid. Its relatively high increase was necessary to make spontaneous spike discharges disappear totally. All effects of the two contrast media, observed in this study, were due to the increase of osmotic pressure of the extracellular fluid ; no specific effect of the contrast media containing the iodine on the indicators used was observed.     

Structure of the baboon endogenous virus genome: cloning of circular virus DNA in bacteriophage lambda.

Linear, small and large circular forms of unintegrated viral DNAs were detected in Hirt supernatant fraction of human cultured cells infected with baboon endogenous virus M7. The circular M7 DNAs were cloned in bacteriophage lambda, Charon 28. Seventeen independent clones were isolated and analyzed by restriction endonuclease mapping. Nine clones were carrying a viral sequence of 8.6 kilobase pairs (kb) with two tandem repeats of 0.6 kb, which correspond to the large circular form of the unintegrated M7 DNA. Eight other clones had the viral insert of 8.0 kb, i. e., the small circular form, and were deleted one of the repeated sequences. The repeated sequences correspond to the long terminal repeats of 0.6 kb, located at both ends of the linear M7 DNA of 8.6 kb. One of the recombinants of the large circular M7 DNA had an inversion of 2.5 kb. One end of the inverted sequence was near the terminus of the long terminal repeats and the other in the gag gene region. The inversion seems to be occurred by integration of a viral DNA within itself during early periods of infection. The mechanism of the processes leading to integration is discussed from the structure of these unintegrated M7 DNAs as the precursors.     

Reaginic antibody formation in the mouse. X. Possible role of suppressor T cells in transient IgE antibody responses.

The kinetics of IgE antibody response to alum-absorbed dinitrophenyl derivatives of ovalbumin (DNP-OA) was dependent on the dose of immunogen. A persistent IgE antibody response was obtained when high responder BDF1 mice were immunized with a minimum (0.05 microgram) dose. An increase of the immunogen to 10 microgram depressed IgE antibody responses but enhanced IgG antibody responses of both hapten and carrier specificities. Determination of T helper cell activity and B memory cells after immunization with different doses of antigen indicated that minimum immunogen was favorable for developing helper activity, whereas 1 to 10 microgram immunogen were more favorable than a 0.05-microgram dose for developing both IgE and IgG B memory cells. Nevertheless, neither helper T cells nor B memory cells in the spleen explains a transient IgE antibody response to a high (10 microgram) dose of DNP-OA. Evidence was obtained that immunization with 10 microgram OA induced generation of antigen-specific suppressor T cells, which were not detectable after immunization with 0.05 microgram OA. Transfer of suppressor T cells to DNP-OA-primed mice depressed both anti-hapten and anti-carrier IgE antibody responses. The results suggested strongly that suppressor T cells are involved in a transient IgE antibody response to a high-dose immunogen.     

Proteasomes: protein and gene structures.

Proteasomes are ring- or cylinder-shaped particles that have a sedimentation coefficient of 20S and are composed of a characteristic set of small polypeptides. These particles have a latent multicatalytic proteinase activity. Recently, proteasomes were found to combine reversibly with multiple protein components to form 26S proteolytic complexes that catalyze ATP-dependent, selective breakdown of proteins ligated with ubiquitin. This suggests that the 26S complexes are a new type of ATP-requiring protease in eukaryotic cells. We have studied the structures of various eukaryotic proteasomes at the molecular level by physicochemical and recombinant DNA techniques and have proposed that the gross structures of proteasomes, such as their size and shape, have been highly conserved during evolution. Proteasome subunits appear to be encoded by a family of homologous genes named the "proteasome gene family," which may have evolved from a common ancestral gene. Evidence obtained by genetic analyses in yeast and studies on the levels of proteasome expression in various eukaryotic cells indicates that proteasomes have essential roles in the cell. In this review, we summarize available information on the protein and gene structures of proteasomes and discuss the biological functions of proteasomes.