Development and tissue-specific distribution of mouse small heat shock protein hsp25

We have investigated the developmental and tissue-specific distribution of the mouse small hsp25 by immunohistology using an antibody that specifically identifies hsp25. Our analysis shows that the relative amount of hsp25 increases during embryogenesis. Through days 13-20 of embryogenesis, hsp25 accumulation is predominant in the various muscle tissues, including the heart, the bladder, and the back muscles. hsp25 is detectable also in neurons of the spinal cord and the purkinje cells. Furthermore analysis of the closely related alpha, B-crystallin shows that in several tissues, including the bladder, the notochordal sheath and the eye lens both proteins are coexpressed. Our studies demonstrate that mammalian hsp25 accumulation is developmentally regulated during mouse embryogenesis and support the view of an important functional role of small heat shock proteins in normal cell metabolism

Identification and genetics of 6-thioguanine secreted by Erwinia species and its interference with the growth of other bacteria.

We identified a compound in culture supernatants of Erwinia species, such as Erwinia amylovora, E. pyrifoliae, E. billingiae, E. tasmaniensis, E. persicina and E. rhapontici absorbing at 340 nm, which was associated before with the yellow pigment produced by E. amylovora on media containing copper ions. The compound was purified from E. tasmaniensis strain Et1/99 supernatants by chromatography on Dowex-1 and Dowex-50 columns and identified by HPLC/MS and NMR analysis as 6-thioguanine (6TG). Its signal at 167 Da matched with the expected molecular mass. By random mutagenesis with miniTn5, we obtained mutants defective in the genes for pyrimidine and purine metabolism. A specific gene cluster with ycf genes described by us before, absent in the corresponding region of Escherichia coli, was identified in the genome sequence of three Erwinia species and named tgs region for thioguanine synthesis. Clones of the tgs gene cluster promoted 6TG synthesis and secretion in E. coli, when the bacteria were grown in minimal medium supplemented with amino acids. 6TG was bacteriostatic for E. coli and Salmonella typhimurium strains, with cell growth resumed after prolonged incubation. Similar results were obtained with P. agglomerans strains. Bacteria from the genus Pectobacterium were barely and Rahnella or Gibbsiella species were not inhibited by 6TG. Adenine and guanine relieved the toxic effect of 6TG on E. coli. Non-producing strains were fully virulent on host plants. 6TG synthesis may help erwinias to interfere with growth of some microorganisms in the environment

Unifying bacteria from decaying wood with various ubiquitous Gibbsiella species as G. acetica sp. nov. based on nucleotide sequencesimilarities and their acetic acid secretion

Bacteria were isolated from necrotic apple and pear tree tissue and from dead wood in Germany andAustria as well as from pear tree exudate in China. They were selected for growth at 37◦C, screenedfor levan production and then characterized as Gram-negative, facultatively anaerobic rods. Nucleotidesequences from 16S rRNA genes, the housekeeping genes dnaJ, gyrB, recA and rpoB alignments, BLASTsearches and phenotypic data confirmed by MALDI-TOF analysis showed that these bacteria belong to thegenus Gibbsiella and resembled strains isolated from diseased oaks in Britain and Spain. Gibbsiella-specificPCR primers were designed from the proline isomerase and the levansucrase genes. Acid secretion wasinvestigated by screening for halo formation on calcium carbonate agar and the compound identified byNMR as acetic acid. Its production by Gibbsiella spp. strains was also determined in culture supernatantsby GC/MS analysis after derivatization with pentafluorobenzyl bromide. Some strains were differentiatedby the PFGE patterns of SpeI digests and by sequence analyses of the lsc and the ppiD genes, and the ChineseGibbsiella strain was most divergent. The newly investigated bacteria as well as Gibbsiella querinecans,Gibbsiella dentisursi and Gibbsiella papilionis, isolated in Britain, Spain, Korea and Japan, are taxonomicallyrelated Enterobacteriaceae, tolerate and secrete acetic acid. We therefore propose to unify them in thespecies Gibbsiella acetica sp. nov