Increased polyamine biosynthesis enhances stress tolerance by preventing the accumulation of reactive oxygen species: T-DNA mutational analysis of Oryza sativa lysine decarboxylase-like protein 1

A highly oxidative stress-tolerant japonica rice line was isolated by T-DNA insertion mutation followed by screening in the presence of 50 mM H₂O₂. The T-DNA insertion was mapped to locus Os09g0547500, the gene product of which was annotated as lysine decarboxylase-like protein (GenBank accession No. AK062595). We termed this gene OsLDC-like 1, for Oryza sativa lysine decarboxylase-like 1. The insertion site was in the second exon and resulted in a 27 amino acid N-terminal deletion. Despite this defect in OsLDC-like 1, the mutant line exhibited enhanced accumulation of the polyamines (PAs) putrescine, spermidine, and spermine under conditions of oxidative stress. The generation of reactive oxygen species (ROS) in the mutant line was assessed by qRT-PCR analysis of NADPH oxidase (RbohD and RbohF), and by DCFH-DA staining. Cellular levels of ROS in osldc-like 1 leaves were significantly lower than those in the wild-type (WT) rice after exposure to oxidative, high salt and acid stresses. Exogenouslyapplied PAs such as spermidine and spermine significantly inhibited the stress-induced accumulation of ROS and cell damage in WT leaves. Additionally, the activities of ROS-detoxifying enzymes were increased in the homozygous mutant line in the presence or absence of H₂O₂. Thus, mutation of OsLDC-like 1 conferred an oxidative stress-tolerant phenotype. These results suggest that increased cellular PA levels have a physiological role in preventing stress-induced ROS and ethylene accumulation and the resultant cell damage.     

Adrenergic innervation of the human gall bladder.

Adrenergic innervation of the human gall bladder was studied using two specific fluorescence histochemical methods. Blue-green fluorescing varicose nerves were scarce and mostly followed the course of blood vessels as typical perivascular plexuses. However, some adrenergic nerves not associated with the vessels were occasionally seen, as well as structures suggestive of a pericellular arrangement of varicose adrenergic nerve terminals on non-fluorescing ganglion cells. A few enterochromaffin cells were seen in the epithelial lining, also in the deep invaginations obviously representing the Aschoff-Rokitansky sinuses. Occasionally, small rounded cells with a rounded, relatively large nucleus, and exhibiting a weak yellow-green to blue-green granular cytoplasmic fluorescence, were observed in the wall of the gall bladder. The possible functional and evolutionary significance of these neural and endocrine elements was discussed against the data on physiological and pharmacological studies obtained from the literature. It was concluded that their significance is, in all probability, secondary to the influence of the intestinal polypeptide hormones, vagal innervation and circulating catecholamines upon the normal function of the gall bladder. The glyoxylic acid-induced fluorescence histochemical method was found to be superior to the conventional formaldehyde technique in studies on human tissue.     

Adrenergic innervation of the human gall bladder

Summary Adrenergic innervation of the human gall bladder was studied using two specific fluorescence histochemical methods. Blue-green fluorescing varicose nerves were scarce and mostly followed the course of blood vessels as typical perivascular plexuses. However, some adrenergic nerves not associated with the vessels were occasionally seen, as well as structures suggestive of a pericellular arrangement of varicose adrenergic nerve terminals on non-fluorescing ganglion cells. A few enterochromaffin cells were seen in the epithelial lining, also in the deep invaginations obviously representing the Aschoff-Rokitansky sinuses. Occasionally, small rounded cells with a rounded, relatively large nucleus, and exhibiting a weak yellow-green to blue-green granular cytoplasmic fluorescence, were observed in the wall of the gall bladder. The possible functional and evolutionary significance of these neural and endocrine elements was discussed against the data on physiological and pharmacological studies obtained from the literature. It was concluded that their significance is, in all probability, secondary to the influence of the intestinal polypeptide hormones, vagal innervation and circulating catecholamines upon the normal function of the gall bladder. The glyoxylic acid-induced fluorescence histochemical method was found to be superior to the conventional formaldehyde technique in studies on human tissue.