Hiromi Uchida

Angiotensin II plays a pathogenic role in immune-mediated renal injury in mice

Several lines of evidence show the importance of angiotensin II (AII) in renal injuries, especially when hemodynamic abnormalities are involved. To elucidate the role of AII in immune-mediated renal injury, we studied anti-glomerular basement membrane (GBM) nephritis in AII type 1a receptor (AT1a)-deficient homozygous (AT1a-/-) and wild-type (AT1a+/+) mice. A transient activation of the renin-angiotensin system (RAS) was observed in both groups of mice at around day 1. A renal expression of monocyte chemoattractant protein-1 (MCP-1) was transiently induced at six hours in both groups, which was then downregulated at day 1. In the AT1a+/+ mice, after RAS activation, the glomerular expression of MCP-1 was exacerbated at days 7 and 14. Thereafter, severe proteinuria developed, and the renal expressions of transforming growth factor-beta1 (TGF-beta1) and collagen type I increased, resulting in severe glomerulosclerosis and interstitial fibrosis. In contrast, glomerular expression of MCP-1, proteinuria, and tissue damage were markedly ameliorated in the AT1a-/- mice. Because this amelioration is likely due to the lack of AT1a, we can conclude that AII action, mediated by AT1a, plays a pathogenic role in anti-GBM nephritis, in which AII may contribute to the exacerbation of glomerular MCP-1 expression. These results suggest the involvement of AII in immune-mediated renal injuries.

Cloning and sequence analysis of poly(tetramethylene succinate) depolymerase from Acidovorax delafieldii strain BS-3.

A gene encoding poly(tetramethylene succinate), PBS, depolymerase, pbsA, has been cloned from Acidovorax delafieldii strain BS-3 chromosomal DNA. The clone expressed in Escherichia coli showed the ability to degrade both PBS and poly[(tetramethylene succinate)-co-adipate] that are kinds of biodegradable plastics. PBS depolymerase was considered to be a kind of lipase, since it also degrades olive oil. It had no apparent hydrophobic-amino-acid-rich region which exists in other known plastic-degrading enzymes. From the result of amino acid homology search, PbsA was found to have some similarities with lipases of Streptomyces sp. and Mollaxella sp. In the motif surrounding the active site Ser residue (Gly-X1-Ser-X2-Gly), PbsA was revealed to have a Trp residue in the X1 position instead of His which is most likely found in other bacterial lipases.

Production of xylose from xylan with intracellular enzyme system of Aspergillus niger 5–16

Abstract Aspergillus niger 5–16 produced a xylanolytic enzyme system, including β-xylosidase, α-glucuronidase and α-arabinofuranosidase, in pellet-shaped mycelia when the fungus grew in a medium including xylan or its partial hydrolysis products as a carbon source. The pellet-shaped mycelia of A. niger 5–16 could be easily converted into a mycelial column after treatment of the pellets with NaN 3 solution. Heteroxylo-oligosaccharides, derived from several xylans hydrolyzed by xylanase of Streptomyces olivaceoviridis E-86, were converted into monosaccharides by passing through the column. The limiting sugar concentration for hydrolysis by the mycelial column was in the order of 5%, because the intracellular β-xylosidase of A. niger 5–16 underwent typical product (xylose) inhibition.