Visual prey discrimination of queen and worker ants by a generalist lizard

Laboratory experiments were conducted to test the hypothesis that widelyforaging generalist lizard,Eumeces okadae, visually discriminates palatable queen ants from unpalatable worker ants. The workers ofCamponotus japonicus andLasius niger were rejected on sight, while the queens of both species were eaten with little prior chemical examination by tongue flicks or licks. Comparison of the lizards' responses towards the workers and wingless queens of similar size indicated that neither body size nor presence or absence of wings accounted for difference in responses toward the 2 ant castes. The lizards probably discriminated different ant castes by body proportions.     

Cloning and Sequencing of Two New Verotoxin 2 Variant Genes of Escherichia coli Isolated from Cases of Human and Bovine Diarrhea

We cloned and sequenced two new Verotoxin 2 (VT2) variant genes: one from an Escherichia coli strain from a case of bovine diarrhea and the other from an E. coli strain from a patient with diarrhea. The nucleotide and amino acid sequences of these two genes were highly homologous with, but distinct from those of the VT2, VT2vha, VT2vhb, SLT-IIv (VT2vp1) and SLT-IIva (VT2vp2) genes. Their nucleotide sequences were much more closely homologous to that of VT2vh than to that of VT2vp. Search for these two new genes in other Verocytotoxin-producing E. coli strains resulted in the isolation of 2 strains carrying one of the new VT2 variant genes, one strain from Tokyo and the other from Canada.     

Molecular analysis of kanamycin and viomycin resistance in Mycobacterium smegmatis by use of the conjugation system.

We examined the molecular mechanisms of resistance to kanamycin and viomycin in Mycobacterium smegmatis. All of the M. smegmatis strains with high-level kanamycin resistance had a nucleotide substitution from A to G at position 1389 of the 16S rRNA gene (rrs). This position is equivalent to position 1408 of Escherichia coli, and mutation at this position is known to cause aminoglycoside resistance. Mutations from G to A or G to T at position 1473 of the M. smegmatis rrs gene were found in viomycin-resistant mutants which had been designated vicB mutants in our earlier studies. Using the M. smegmatis conjugation system, we confirmed that these mutations indeed contributed to kanamycin and viomycin resistance, and kanamycin susceptibility was dominant over resistance in a heterogenomic strain. Additional experiments showed that three of four Mycobacterium tuberculosis strains with high-level kanamycin resistance had a mutation from A to G at position 1400, which was equivalent to position 1389 of M. smegmatis.     

Regeneration of whole plants from protoplasts isolated from tissue-cultured shoot primordia of garlic (Allium sativum L.)

Protoplasts derived from tissue-cultured shoot primordia of garlic (Allium sativum L.) initiated successive cell divisions within 4 days and formed small individual calli (0.2mm in diameter) after 5 weeks of culture on Gamborg's B5 medium supplemented with 0.1% casein hydrolysate, 1mg/1 1-naphthaleneacetic acid and 1mg/1 6-benzylaminopurine. Plating efficiency was roughly 5% at the density of 1x10⁴ protoplasts/ml of medium. Adventitious buds developed from the calli during subsequent subculture on Gamborg's B5 medium supplemented with 40mg/l adenine and 10% coconut milk. When transferred to the same medium without supplements, these buds grew into shoots and rooted. The regenerated garlic plantlets were successfully transferred to the greenhouse and grew into whole plants.     

Siblings with renal tubular acidosis and nerve deafness. The first family in Japan

Summary Two siblings with renal tubular acidosis (RTA) and nerve deafness were examined. It was found by ammonium chloride and bicarbonate loading tests that the 6-year-old brother had a hybrid type of RTA and his 4-year-old sister, a distal type of RTA. Enzyme activity and amount of enzyme protein of carbonic anhydrase isoenzyme I and II in red blood cells, measured using an immunoadsorbent method, were normal in both cases. Although this indicated that the RTAs of these patients are not generated by the carbonic anhydrase deficiency, an investigation with renal tissue is necessary to arrive at a final conclusion.     

Intracellular utilization of superoxide anion by indoleamine 2,3-dioxygenase of rabbit enterocytes.

The participation of superoxide anion (O2-) in the intracellular indoleamine 2,3-dioxygenase activity was studied using the dispersed cell suspension of the rabbit small intestine. The dioxygenase activity was assayed by measuring [14C]formate released from DL-[ring-2-14C]tryptophan. The addition of diethyldiethiocarbamate, a superoxide dismutase inhibitor, markedly accelerated the intracellular dioxygenase activity while the superoxide dismutase activity decreased concomitantly. Furthermore, substrates of xanthine oxidase such as inosine, adenosine, and hypoxanthine also increased the dioxygenase activity in the cells, particularly in the presence of methylene blue. This increase was completely abolished by the addition of allopurinol, a specific inhibitor of xanthine oxidase. These results, taken together, indicate that the intracellular accumulation of O2- results in acceleration of the in situ dioxygenase activity, and that indoleamine 2,3-dioxygenase utilizes O2- in the isolated intestinal cells.     

Mitogenic responsiveness and monocyte-lymphocyte interaction of early and late rosette-forming cell populations of human peripheral blood lymphocytes.

Adherent cells in human peripheral blood mononuclear cells were removed by the attachment to the plastic surface of tissue culture dishes. After removal of adherent cells, early rosette-forming cells (early RFC), which were characterized by early (5 min) rosette formation with sheep blood cells (SRBC) at an SRBC to lymphocyte ratio of 8:1, were separated from nonrosetting cells by sedimentation on Ficoll-Hypaque gradient. Total (60 min) rosette formation was carried out with the early RFC-depleted cell population on the gradient interface by the use of neuraminidase-treated SRBC at an SRBC to lymphocyte ratio of 20:1 and the resulting rosette-forming cells (late RFC) were sedimented by gradient centrifugation. These T cell subpopulations, early RFC-enriched and late RFC-enriched, were reasonably pure with respect to the ability to bind SRBC and contained less than 0.5% monocytes. Monocyte preparations, which were obtained after vigorous washing of the adherent cell layers on tissue culture dishes, responded to phytohemagglutinin P (PHA-P) or concanavalin A (Con A) with negligible incorporation of 3H-thymidine. There was no significance difference in the responsiveness to PHA-P between early RFC-enriched and late RFC-enriched populations either in the absence or in the presence of graded numbers of additional autologous monocytes. However, the response of early RFC-enriched population to Con A was significantly poor as compared with that of late RFC-enriched one unless additional monocytes were added. In the presence of 20% autologous monocytes in the culture, the Con A-induced response of early RFC-enriched population was markedly enhanced to reach close to that of late RFC-enriched population. These results suggest that early RFC and late RFC might be different from each other in their responsiveness and in their need for monocytes on the stimulation with Con A.