Comparison of bacterial community structures in the rhizoplane of tomato plants grown in soils suppressive and conducive towards bacterial wilt.

It has been reported that the growth of Ralstonia solanacearum is suppressed at the rhizoplane of tomato plants and that tomato bacterial wilt is suppressed in plants grown in a soil (Mutsumi) in Japan. To evaluate the biological factors contributing to the suppressiveness of the soil in three treated Mutsumi soils (chloroform fumigated soil; autoclaved soil mixed with intact Mutsumi soil; and autoclaved soil mixed with intact, wilt-conducive Yamadai soil) infested with R. solanacearum, we bioassayed soil samples for tomato bacterial wilt. Chloroform fumigation increased the extent of wilt disease. More of the tomato plant samples wilted when mixed with Yamadai soil than when mixed with Mutsumi soil. Consequently, the results indicate that the naturally existing population of microorganisms in Mutsumi soil was significantly able to reduce the severity of bacterial wilt of tomato plants. To characterize the types of bacteria present at the rhizoplane, we isolated rhizoplane bacteria and classified them into 22 groups by comparing their 16S restriction fragment length polymorphism patterns. In Yamadai soil a single group of bacteria was extremely predominant (73.1%), whereas in Mutsumi soil the distribution of the bacterial groups was much more even. The 16S rDNA sequence analysis of strains of dominant groups suggested that gram-negative bacteria close to the beta-proteobacteria were most common at the rhizoplane of the tomato plants. During in vitro assays, rhizoplane bacteria in Mutsumi soil grew more vigorously on pectin, one of the main root exudates of tomato, compared with those in Yamadai soil. Our results imply that it is difficult for the pathogen to dominate in a diversified rhizobacterial community that thrives on pectin.     

Intensification of galactosamine hepatotoxicity by polyriboinosinic acid-polyribocytidylic acid

The effects of polyriboinosinic acid-polyribocytidylic acid (poly IC) on galactosamine-induced liver cell injury in rats were studied. Treatment of rats with D-galactosamine-HC1 (400 mg/kg) increased their serum glutamate-oxaloacetate transaminase (E.C.2.6.1.1, GOT) activities, indicating that hepatocyte injury was induced by galactosamine. Rapid and intense elevations of serum GOT activities were observed when galactosamine (200 mg/kg) was administered simultaneously with poly IC (10 mg/kg) but not with poly I or poly C. Acute increase in serum GOT activities caused by the simultaneous administration of poly IC and galactosamine was prevented by the simultaneous administration of uridine (1 g/kg), which is known to inhibit the early biochemical alterations caused by the amino sugar in the hepatocyte. These findings suggest that poly IC intensifies the hepatotoxic effect of galactosamine in rats. This poly IC-induced sensitization was inhibited by pretreatment with poly IC (10 mg/kg) itself, when injected 24 hr before the administration of the hepatotoxin together with poly IC.     

Variation in Splicing Efficiency Underlies Morphological Evolution in Capsella

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Improvement of S-adenosylmethionine production by integration of the ethionine-resistance gene into chromosomes of the yeast Saccharomyces cerevisiae

An ethionine-resistance gene cloned from Saccharomyces cerevisiae DKD-5D-H was able to enhance S-adenosyl-l-methionine (AdoMet) accumulation when it was introduced into the yeast cells on multi-copy plasmid YEp13. In order to increase the AdoMet accumulation, the gene was integrated into the yeast chromosome by using a yeast transposon Ty element. When the YEp plasmid was used for the integration, the ethionine-resistance gene was efficiently inserted into the yeast chromosomes with a substantial increase in AdoMet productivity (about twofold) in comparison with that by the yeast cells carrying the gene on an extrachromosomal multi-copy plasmid.     

Time course of recovery from nerve injury in skeletal muscle: energy state and local circulation

Hayashi, Yoshihiro, Takaaki Ikata, Hiroaki Takai, ShinjiroTakata, Takayuki Sogabe, and Keiko Koga. Time course of recoveryfrom nerve injury in skeletal muscle: energy state and localcirculation. J. Appl. Physiol. 82(3):732-737, 1997.This study examined the time course of recoveryfrom nerve injury on energy state assessed by phosphorus-31 magneticresonance spectroscopy and local circulation dynamics by fluorine-19magnetic resonance spectroscopy in skeletal muscles ofrats. The hindlimb muscles that had undergone unilateralsciatic nerve compression for 2 wk (CN) were compared withsham-operated (SO) muscles and with muscles that had the compressionremoved after 2 wk and were allowed to recover for 4 wk (R4) or for 6 wk (R6). The energy state and local circulation dynamics of CN muscleswere less than those of SO muscles (P < 0.01). The energy state of R4 muscles remained at levels similar toCN muscles, whereas the local circulation dynamics improved but notback to SO values. In R6 muscles, both parameters returned to SOvalues. These results showed that the recovery processes of circulationprecede those of energy state in skeletal muscles.

     

Comparative Genome Mapping of the Ataxia–Telangiectasia Region in Mouse, Rat, and Syrian Hamster

Chromosomal locations of theAtm(ataxia–telangiectasia (AT)-mutated) andAcat1(mitochondrial acetoacetyl-CoA thiolase) genes in mouse, rat, and Syrian hamster were determined by direct R-banding FISH. Both genes were colocalized to the C-D band of mouse chromosome 9, the proximal end of q24.1 of rat chromosome 8, and qa4–qa5 of Syrian hamster chromosome 12. The regions in the mouse and rat were homologous to human chromosome 11q. Fine genetic linkage mapping of the mouse AT region was performed using the interspecific backcross mice.Atm, Acat1,andNpat,which is a new gene isolated from the AT region, and 12 flanking microsatellite DNA markers were examined. No recombinations were found among theAtm, Npat, Acat1,andD9Mit6loci, and these loci were mapped 2.0 cM distal toD9Mit99and 1.3 cM proximal toD9Mit102.Comparison of the linkage map of mouse chromosome 9 (MMU9) and that of human chromosome 11 (HSA11) indicates that there is a chromosomal rearrangement due to an inversion betweenEts1andAtm–Npat–Acat1and that the inversion of MMU9 originated from the chromosomal breakage at the boundary betweenGria4andAtm–Npat–Acat1on HSA11. This type of inversion appeared to be conserved in the three rodent species, mouse, rat, and Syrian hamster, using additional comparative mapping data with theRckgene.     

Isolation of temperature-sensitive mutants from murine leukemic cells (L5178Y)

Two temperature-sensitive mutants (ts1 and ts3) have been isolated from murine leukemic cells, L5178Y, after mutagenesis and cytosine arabinoside selection. Both ts1 and ts3 grew normally at the permissive temperature (33 °C) but not at the non-permissive temperature (39 °C). Consistent results were obtained with the growth patterns in suspension culture as well as the plating efficiencies in soft agar. Temperature shift experiments showed that the mutant cells remained viable after extended exposure to the non-permissive temperature. Labeling studies with radioactive precursors indicated that the synthesis of DNA, but not of RNA or protein, was affected in these mutants at 39 °C. The defective function of ts3 cells was substantially corrected by supplementing alanine, hypoxanthine, and pyruvate.     

Proteins and RNA in mouse L cell core nucleoli and nucleolar matrix

When intact nucleoli were prepared in the presence of enough leupeptin and phenylmethanesulfonyl fluoride to inhibit protease action, electrophoretic patterns of their constituent proteins were reproducible and very similar for L, HeLa, CHO, and rat hepatoma cells. "Core nucleoli", defined as that nucleolar fraction which remains after extensive DNase I action, had a protein composition similar to that of crude intact nucleoli, but were enriched for snRNA U3. Core nucleolar proteins included all of the histones, ribosomal proteins, and phosphorylated proteins with mobilities corresponding to 110 (protein C23) and 160 kilodaltons (kDa). The presence of protein C23 and of lamins A and C in nucleoli and core nucleoli was further verified by reaction with specific antibodies after one- or two-dimensional electrophoresis. A class of higher molecular weight proteins, ranging from 70 to greater than 200 kDa by mobility, was observed. It included at least 25 specific proteins, almost all of them highly acidic (pI less than 3.5). Treatment of core nucleoli with ethylenediaminetetraacetic acid/hypotonic buffer solubilized 30-35% of the small and large molecular weight proteins. In contrast, washing core nucleoli with 2 M NaCl selectively released U3 snRNA, 95% of the ribosomal RNA, and about half of the proteins, including C23 and most of the histones, ribosomal proteins, and other lower molecular weight proteins. The fraction remaining insoluble, "nucleolar matrix", was enriched for proteins of 34 and 57 kDa, lamins A and C, and most higher molecular weight proteins, as well as a portion of ribosomal spacer DNA.     

Immobilization of Enzyme into Poly(vinyl alcohol) Membrane

Glucoamylase, invertase, and cellulase were entrapped within poly(vinyl alcohol) (PVA) membrane cross-linked by means of irradiation of ultraviolet light. The conditions for immobilization of glucoamylase were examined with respect to enzyme concentration in PVA, sensitizer (sodium benzoate) concentration in PVA, irradiation time, and membrane thickness. Various characteristics of immobilized glucoamylase were evaluated. Among them, the pH activity curve for the immobilized enzyme was superior to that for the native one, and thermal stability was improved by immobilization with bovine albumin. The apparent K(m) was larger for immobilized glucoamylase than for the native one, while V(max) was smaller for the immobilized enzyme. Also, the apparent K(m) appeared to be affected by the molecular size of the substrate. Further, immobilized invertase and cellulase showed good stabilities in repeating usage.