Genes that are uniquely stress regulated in salt overly sensitive (sos) mutants

Repetitive rounds of differential subtraction screening, followed by nucleotide sequence determination and northern-blot analysis, identified 84 salt-regulated (160 mM NaCl for 4 h) genes in Arabidopsis wild-type (Col-0 gl1) seedlings. Probes corresponding to these 84 genes and ACP1, RD22BP1, MYB2, STZ, and PAL were included in an analysis of salt responsive gene expression profiles in gl1 and the salt-hypersensitive mutant sos3. Six of 89 genes were expressed differentially in wild-type and sos3 seedlings; steady-state mRNA abundance of five genes (AD06C08/unknown, AD05E05/vegetative storage protein 2 [VSP2], AD05B11/S-adenosyl-L-Met:salicylic acid carboxyl methyltransferase [SAMT], AD03D05/cold regulated 6.6/inducible2 [COR6.6/KIN2], and salt tolerance zinc finger [STZ]) was induced and the abundance of one gene (AD05C10/circadian rhythm-RNA binding1 [CCR1]) was reduced in wild-type plants after salt treatment. The expression of CCR1, SAMT, COR6.6/KIN2, and STZ was higher in sos3 than in wild type, and VSP2 and AD06C08/unknown was lower in the mutant. Salt-induced expression of VSP2 in sos1 was similar to wild type, and AD06C08/unknown, CCR1, SAMT, COR6.6/KIN2, and STZ were similar to sos3. VSP2 is regulated presumably by SOS2/3 independent of SOS1, whereas the expression of the others is SOS1 dependent. AD06C08/unknown and VSP2 are postulated to be effectors of salt tolerance whereas CCR1, SAMT, COR6.6/KIN2, and STZ are determinants that must be negatively regulated during salt adaptation. The pivotal function of the SOS signal pathway to mediate ion homeostasis and salt tolerance implicates AD06C08/unknown, VSP2, SAMT, 6.6/KIN2, STZ, and CCR1 as determinates that are involved in salt adaptation.     

Lepidimoic acid increases fructose 2,6-bisphosphate in Amaranthus seedlings

This study examines the influence of the growth promoter, lepidimoic acid, on the level of an important cytosolic signal metabolite, fructose 2,6-bisphosphate (Fru-2,6-P2), which can activate pyrophosphatedependent:phosphofructokinase (PFP, EC 2.7.1.90), and on glycolytic metabolism in Amaranthus caudatus seedlings. Fru-2,6-P2 concentrations were respectively increased by approximately 2-, 3- and 4-fold when the seedlings were treated with 0.3, 3 and 30 mM lepidimoic acid. Exogenous lepidimoic acid also affected levels of glycolytic intermediates in the seedlings. The increase in fructose 1,6-bisphosphate and decreases in fructose 6-phosphate and glucose 6-phosphate were found in response to the elevated concentration of lepidimoic acid. These results suggest that lepidimoic acid may affect glycolytic metabolism in the Amaranthus seedlings by increasing the activity of PFP due to increasing level of Fru-2,6-P2.     

A species-selective allelopathic substance from germinating sunflower (Helianthus annuus L.) seeds

From the exudate of germinating sunflower (Helianthus annuus L.) seeds was isolated a stereoisomer of diversifolide, 4, 15-dinor-3-hydroxy-1(5)-xanthene-12,8-olide (designated sundiversifolide) as determined by analysis of its IR, APCI-, ESI- and HR-MS and 13C and 1H NMR spectra. This substance inhibited shoot and root growth of cat's-eyes by about 50% at a concentration of 30 ppm. It also showed species-selective activity on the shoot and root growth of tested plants. When cat's-eyes seeds were incubated together with sunflower seeds, the cat's-eyes growth was inhibited. Furthermore, it was detected from an extract of river sand when sunflower seeds were incubated on the sand. These results indicate that sundiversifolide has an allelopathic function in sunflower plants.     

Intraspecific phylogeny and geographical variation of six species of northeastern Asiatic Sorex shrews based on the mitochondrial cytochrome b sequences

Intraspecific phylogeny and genetic variation were investigated based on nucleotide sequences of the mitochondrial cytochrome b gene in six soricine shrew species, Sorex unguiculatus, S. caecutiens, S. shinto, S. gracillimus, S. minutissimus and S. hosonoi, collected primarily from northeastern Asia. Maximum likelihood trees and a phylogenetic network were generated to estimate intraspecific phylogenies. S. minutissimus showed high congruence between phylogenetic position and geographical origin and S. gracillimus showed low congruence. In contrast, there was no congruence between phylogeny and geography in S. unguiculatus and the S. caecutiens from Sakhalin-Eurasia. Positive correlation between genetic and geographical distances was found in S. minutissimus and S. gracillimus, but not in the other species (or regional populations). The results of the phylogenetic and genetic analyses suggest that S. minutissimus and S. gracillimus have occupied their present ranges for a longer time than the other species if we assume a stepping-stone model of population structure. In addition, there was no contradiction between the present investigations and the hypotheses of multiple immigration by S. gracillimus and a single immigration by S. unguiculatus into Hokkaido Island. It is proposed that these six northeastern Asian species experienced different historical processes of range expansion and dispersal despite the fact that some of them currently show similar patterns of distribution.     

Complete nucleotide sequence and gene rearrangement of the mitochondrial genome of the Japanese pond frog Rana nigromaculata

In this study, we determined the complete nucleotide sequence of the mitochondrial genome of the Japanese pond frog Rana nigromaculata. The length of the sequence of the frog was 17,804 bp, though this was not absolute due to length variation caused by differing numbers of repetitive units in the control regions of individual frogs. The gene content, base composition, and codon usage of the Japanese pond frog conformed to those of typical vertebrate patterns. However, the comparison of gene organization between three amphibian species (Rana, Xenopus and caecilian) provided evidence that the gene arrangement of Rana differs by four tRNA gene positions from that of Xenopus or caecilian, a common gene arrangement in vertebrates. These gene rearrangements are presumed to have occurred by the tandem duplication of a gene region followed by multiple deletions of redundant genes. It is probable that the rearrangements start and end at tRNA genes involved in the initial production of a tandemly duplicated gene region. Putative secondary structures for the 22 tRNAs and the origin of the L-strand replication (OL) are described. Evolutionary relationships were estimated from the concatenated sequences of the 12 proteins encoded in the H-strand of mtDNA among 37 vertebrate species. A quartet-puzzling tree showed that three amphibian species form a monophyletic clade and that the caecilian is a sister group of the monophyletic Anura.     

Recombinant Sendai virus vectors deleted in both the matrix and the fusion genes: efficient gene transfer with preferable properties

BACKGROUND: Sendai virus (SeV) is a new type of cytoplasmic RNA vector, which infects and replicates in most mammalian cells, directs high-level expression of the genes on its genome and is free from genotoxicity. In order to improve this vector, both the matrix (M) and fusion (F) genes were deleted from its genome. METHODS: For the recovery of the M and F genes-deleted SeV (SeV/DeltaMDeltaF), the packaging cell line was established by using a Cre/loxP induction system. SeV/DeltaMDeltaF was characterized and compared with wild-type and F or M gene-deleted SeV vectors in terms of transduction ability, particle formation, transmissible property and cytotoxicity. RESULTS: SeV/DeltaMDeltaF was propagated in high titers from the packaging cell line. When this vector was administered into the lateral ventricle and the respiratory tissue, many of the ependymal and epithelial cells were transduced, respectively, as in the case of wild-type SeV. F gene-deletion made the SeV vector non-transmissible, and M gene-deletion worked well to inhibit formation of the particles from infected cells. Simultaneous deletions of these two genes in the same genome resulted in combining both advantages. That is, both virus maturation into particles and transmissible property were almost completely abolished in cells infected with SeV/DeltaMDeltaF. Further, the cytopathic effect of SeV/DeltaMDeltaF was significantly attenuated rather than that of wild type in vitro and in vivo. CONCLUSIONS: SeV/DeltaMDeltaF is an advanced type of cytoplasmic RNA vector, which retains efficient gene transfer, gains non-transmissible properties and loses particle formation with less cytopathic effect.     

Factors determining prognosis in streptococcal toxic shock-like syndrome: results of a nationwide investigation in Japan

Since the first report of streptococcal toxic shock-like syndrome (TSLS) in Japan, the numbers of reported patients have been increasing. However, clinical manifestations remain somewhat unclear, and factors potentially defining prognosis remain to be identified. We conducted a retrospective nationwide postal survey of major Japanese hospitals concerning clinical manifestations of invasive streptococcal infections including necrotizing fasciitis and TSLS. We evaluated 30 patients who died and 36 survivors. The overall mortality rate was 45%. Physical and laboratory findings on admission were compared statistically between fatal cases and surviving patients. Most laboratory results from the patients who died showed greater abnormality than results from the survivors. Patients who died had significantly fewer leukocytes and platelets, although their C-reactive protein concentrations were similar to those in survivors. Creatinine was significantly higher, and temperature and blood pressure were significantly lower, in patients who died. Patients with invasive streptococcal infections should be managed aggressively when the above features are present.     

Short-term exposure of high glucose concentration induces generation of reactive oxygen species in endothelial cells: implication for the oxidative stress associated with postprandial hyperglycemia

Recent studies demonstrating a close relationship between postprandial hyperglycemia and the incidence of atherosclerotic cardiovascular disease prompted us to investigate the generation and source of reactive oxygen species (ROS) in endothelial cells stimulated by short-term exposure to a high glucose concentration. In addition, we investigated the effect of insulin on ROS production induced by high glucose concentration. Cultured bovine aortic endothelial cells demonstrated a significant increase in intracellular ROS generation after a 3-h exposure to 25 mM glucose (131.4% versus 5 mM glucose). This increased generation of ROS was suppressed by an inhibitor of NAD(P)H oxidase. Intracellular ROS production in cells exposed to 3 h of high glucose concentration was increased significantly by the presence of a physiological concentration of insulin. However, after a 1-h exposure to high glucose levels, ROS generation in cells incubated with insulin was only about 80% of that measured in cells incubated without insulin. The generation of intracellular nitric oxide (NO) resulting from an acute insulin effect may account for this difference. In conclusion, acute hyperglycemia itself may possibly cause endothelial oxidative stress in patients with postprandial hyperglycemia. Endothelial oxidative stress may be determined by the interaction between NO and superoxide generation.