Regeneration of beech (Fagus crenata) after the simultaneous death of undergrowing dwarf bamboo (Sasa kurilensis)

Seedling recruitment and survivorship of beech (Fagus crenata) were studied with special reference to the simultaneous death of undergrowing bamboo (Sasa kurilensis). The survival rate of beech seedlings on the floor whereSasa had withered was much higher than that on the floor whereSasa survived. Damping off caused the largest mortality among beech seedlings. However, the allocation pattern of matter to different parts of the seedlings indicated that their survival was greatly affected by production economy. The dense cover of dwarf bamboo prevented the establishment of beech seedling banks on the forest floor. The interval between the times when simultaneous death ofSasa occur and the length of its recovery period are thus important factors controlling the dynamics of beech forests in Japan.     

A comparative study on immunosuppressive effects of cyclosporin A and FK 506 on peripheral blood lymphocytes in dogs

Immunosuppressive effects of cyclosporin A (CsA) and FK 506 (FK) on peripheral blood lymphocytes were studied in dogs in respect to mixed lymphocyte reaction, proliferative responses to recombinant interleukin-2 (rIL-2), phytohemagglutinin (PHA) and concanavalin-A (Con-A); phenotypes of OKIa1, CD3, CD8 and surface IgM; cytotoxic activity against xenogeneic tumor cells. CsA (2.0 or 5.0 mg/kg, intravenously) or FK (0.16 mg/kg, intramuscularly) was given to mongrel dogs every morning for serial 21 days. The blood concentrations of CsA, measured as trough levels by fluorescence polarization method, ranged from 37 to 350 ng/ml in dogs administered at 2.0 mg/kg and from 170 to 894 ng/ml in dogs administered at 5.0 mg/kg during treatment, respectively. In dogs treated with FK at a dose of 0.16 mg/kg, the drug concentrations in the plasma during treatment ranged from 0.16 to 1.8 ng/ml. Mixed lymphocyte reaction and proliferative responses to rIL-2, PHA and Con-A, which were declined by CsA, were not affected by FK. In contrast, the proportion of OKIa1+ cells was not affected by CsA, whereas FK decreased the proportion of OKIa1+ cells progressively during the course of treatment. Cytotoxic activity was suppressed by both CsA and FK. These results possibly indicate that CsA and FK exert their immunosuppressive effects via different mechanisms.     

Increased expression in vivo and in vitro of foreign genes directed by A-type inclusion body hybrid promoters in recombinant vaccinia viruses.

We constructed A-type inclusion body (ATI) hybrid promoters, that is, late ATI promoters followed by tandemly repeated early regions of the promoter for the 7.5-kDa protein (the 7.5-kDa promoter). The repetition of the whole early promoter sequence of the 7.5-kDa gene, including the upstream consensus sequence and initiation region, efficiently increased the early expression of the bacterial chloramphenicol acetyltransferase gene in recombinant vaccinia virus. Recombinant vaccinia virus could express influenza virus hemagglutinin via the hybrid promoter more efficiently, induced higher levels of neutralizing antibody and cytotoxic T lymphocytes, and consequently protected mice more efficiently against challenge with influenza virus than did recombinant vaccinia virus containing the widely used 7.5-kDa promoter.     

Enhancement of ATPase Activity by a Lipid Peroxide of Arachidonic Acid in Rat Brain Microvessels

The effects of 15-hydroperoxyarachidonic acid (15-HPAA) on Na+, K+- and Mg+-ATPase activities in the blood-brain barrier (BBB) were examined using rat brain microvessels (MV). 15-HPAA markedly stimulated these ATPase activities in MV at low concentrations whereas the synaptosomal Na+, K+-ATPase activity was inhibited in a dose-dependent manner. Further neurochemical analysis revealed that this stimulatory effect of 15-HPAA in MV was not due to a simple detergent-like action of the compound on the membranes but rather to stimulation of the phospholipase A2 and lipoxygenase activity within MV. In addition, it was shown that free radical reactions were involved in the mechanism. Since such anti-edema drugs as 1,2-bis(nicotinamido)propane were proved to be potent suppressors of the enhanced ATPase activity, further speculations on the role of this effect for ischemic brain edema are offered.     

Isolation of an autonomously replicating sequence (ARS) from satellite DNA of Drosophila melanogaster

Summary Autonomously replicating sequences (ARSs) were cloned from the 1.688 satellite DNA of D. melanogaster using YIp5, consisting of pBR322 and the yeast ura3 gene, as the cloning vector and YNN27, a Ura^– yeast strain as the recipient. Three out of six clones contained an ARS and the average frequncy of the occurrence of ARS was thus calculated to be approximately one per 14 kbp of the satellite DNA. A 500 bp ARS fragment (BgHS500) was obtained from one of the resultant clones (pYDS57). BgHS500 does not hybridize with the major repeating unit (370 bp) but it does with the minor unique sequence of the satellite. The sequence of BgHS500 was determined and found to be rich in AT and to contain the sequence, 5AAAACATAAAA3, a sequence common to yeast ARSs. However, a smaller fragment (150 bp) isolated from BgHS500 and containing the 11 bp sequence did not exhibit the characteristics of an ARS. The average copy number in the transformants of pBgHS500, a recombinant molecule of BgHS500 and YIp5, ranged from 0.05–0.5, while that of the parent plasmid, pYDS57, was about 2–10. On the basis of these results, it is postulated that the sequence 5AAAACATAAAA3 may possibly consiitute the core of ARSs and certain other sequences may also be necessary to insure that the ARS consistently undergoes at least one complete replication in each cell cycle. The role of ARSs in the genome of D. melanogaster is discussed.     

Immunotherapy with bestatin for acute nonlymphocytic leukemia in adults

Summary In a cooperative randomized control study of immunotherapy with bestatin in combination with chemotherapy in adults with acute nonlymphocytic leukemia (ANLL), 101 patients (48 in the bestatin group and 53 in the control group) out of 115 patients registered were evaluated as eligible. The bestatin group achieved a statistically significant prolongation of survival compared with the control group in overall ANLL and acute myelogenous leukemia. In the analysis of patient age, the bestatin group achieved a statistically significant prolongation of both the remission duration and survival in patients aged 50 to 65 years, while the differences were not significant in the 15 to 49 age group. The bestatin group tended to achieve a higher rate of reinduction of remission in patients who had recurrence of leukemia. Side effects developed in only 5 (9.6%) of 52 patients treated with bestatin. None of these side effects were particularly serious in nature. It is concluded that bestatin is useful for prolongation of survival of adult patients with ANLL, making for a longer remission duration especially in elderly patients and with few side effects.     

Replication of Deoxyribonucleic Acid in Escherichia coli C Mutants Temperature Sensitive in the Initiation of Chromosome Replication

An Escherichia coli HF4704S mutant temperature sensitive in deoxyribonucleic acid (DNA) synthesis and different from any previously characterized mutant was isolated. The mutated gene in this strain was designated dnaH. The mutant could grow normally at 27 C but not at 43 C, and DNA synthesis continued for an hour at a decreasing rate and then ceased. After temperature shift-up, the increased amount of DNA was 40 to 50%. When the culture was incubated at 43 C for 70 min and then transferred to 27 C, DNA synthesis resumed after about 50 min, initiating synchronously at a fixed region on the bacterial chromosome. The initiation step in DNA replication sensitive to 30 mug of chloramphenicol per ml occurs synchronously before the resumption of DNA replication after the temperature shift-down, being completed about 30 min before the start of DNA replication. When the cells incubated at 27 C in the presence of 30 mug of chloramphenicol per ml after the temperature shift-down to 27 C were transferred to 43 C with simultaneous removal of the antibiotic, no resumption of DNA replication was observed. When the culture was returned to 43 C after being released from high-temperature inhibition at 30 min before the start of DNA replication, no recovery replication was observed; whereas at 20 min, the recovery of replication was observed. These results indicated that HF4704S was temperature sensitive in the initiation of DNA replication. Analysis of HF4704S, by an interrupted conjugation experiment, indicated that gene dnaH was located at about 64 min on the E. coli C linkage map. In E. coli S1814 (a K-12 derivative), which was a dnaH(ts) transductant from HF4704S (C strain) with phage P1, the mutated gene (dnaH) was demonstrated to be closely linked to the thyA marker by conjugation and P1 transduction experiments and to be distinct from genes dnaA through dnaG.