A Novel Isourazole Herbicide, Fluthiacet-Methyl, is a Potent Inhibitor of Protoporphyrinogen Oxidase after Isomerization by Glutathione S-Transferase

A novel isourazole herbicide, fluthiacet-methyl (methyl [[2-chloro-4-fluoro-5-[(5,6,7,8-tetrahydro-3-oxo-lH,3H-[l,3,4]thiadiazolo[3,4-a]pyridazin-l-ylidene)amino]phenyrjthio]acetate;experimental code name, KIH-9201) promoted the leakage of electrolytesfrom cotyledons of velvetleaf (Abtilon theophtasti Medic) andcotton (Gossypium hirsutum L.) plants that are sensitive tothis compound. It induced the accumulation of protoporphyrinIX in cotyledons of cotton and inhibited Chl biosynthesis incotyledons of velvetleaf and cotton at low concentrations (I₅₀values, 10–12 nM). Fluthiacet-methyl was converted toits urazole by glutathione S-transferase that had been partiallypurified from velvetleaf. The urazole inhibited protoporphyrinogenoxidase (Protox, EC 1.3.3.4 [EC] ) from some plants, including velvetleaf,at low concentrations (I₅₀ values, 5.1–11 nM), whereasfluthiacet-methyl was not as potent. The effects in vivo (electrolyteleakage and inhibition of Chi biosynthesis) of fluthiacet-methylwere correlated with the inhibition of Protox activity by theurazole and not with the action of fluthiacet-methyl itself.From these results, it is concluded that fluthiacet-methyl inhibitsProtox activity after conversion to the corresponding urazoleby glutathione S-transferase. It is in this way that fluthiacet-methylexerts its effect as a light-dependent peroxidizing herbicide. (Received November 1, 1994; Accepted March 6, 1995)     

Isolation and Characterization of Hardening-Induced Proteins in Chlorella vulgaris C-27: Identification of Late Embryogenesis Abundant Proteins

Hardening-induced soluble proteins of Chlorella vulgaris BeijerinkIAM C-27 (formerly Chlorella ellipsoidea Gerneck IAM C-27) wereisolated and purified by two-dimensional high-performance liquidchromatography (2D-HPLC) on an anion-exchange column, with subsequentreversed-phase chromatography. Some of the proteins were resolvedby SDS-PAGE, characterized by amino-terminal sequencing andidentified by searching for homologies in databases. Separationof the soluble proteins during the hardening of Chlorella bya combination of 2D-HPLC and SDS-PAGE revealed that at least31 proteins were induced or increased in abundance. Of particularinterest was the induction after 12 h of a 10-kDa protein withthe amino-terminal amino acid sequence AGNKPITEQISDAVGAAGQKVGand the induction after 6 h of a 14-kDa protein with the amino-terminalsequence ALGEESLGDKAKNAFEDAKDAVKDAAGNVKEAV. The amino-terminalsequences of these proteins indicated that they were homologousto late embryogenesis abundant (LEA) proteins. Furthermore,the level of a 22-kDa protein also increased after 12 h. Theamino-terminal sequence of this protein, AAPLVGGPAPDFTAAAVFD,indicated that it was homologous to thioredoxin peroxidase. (Received June 9, 1995; Accepted September 12, 1995)     

Intercolonial differences in raiding activities in the Japanese slave-making antPolyergus samurai

Summary Intercolonial differences in raiding activity were investigated in the field on 9 colonies of the slavemaking antPolyergus samurai. Duration of raiding season, the mean start time of the first raiding trip in a day, the mean speed of outbound and inbound trips, and the mean distance to target nests varied significantly among colonies. The variance in start time of raiding was correlated with that in soil temperature and diurnal change pattern in soil temperature at the nest sites. The speed of trips and the first day with trips in the season also correlated with soil temperature at the nest site. Simple environmental factors well explained the observed variances in raiding activity among colonies. Therefore, raiding behaviour ofP. samurai seemed to be a stereotyped behaviour that is regulated through simple environmental factors.     

Expression of hepatic calcium-binding protein regucalcin mRNA is elevated by refeeding of fasted rats: Involvement of glucose,insulin and calcium as stimulating factors

The effect of refeeding on the expression of Ca²⁺-binding protein regucalcin mRNA in the liver of fasted rats was investigated. When rats were fasted overnight, the hepatic regucalcin mRNA level was reduced about 70% of that in feeding rats. Refeeding produced a remarkable elevation of hepatic regucalcin mRNA level (about 150–170% of fasted rats). Liver regucalcin concentration was appreciably increased by refeeding, although it was not altered by fasting. The oral administration of glucose (2 g/kg body weight) to fasted rats caused a significant increase in hepatic regucalcin mRNA level. Moreover, hepatic regucalcin mRNA level was clearly elevated by a single subcutaneous administration of insulin (10 and 100 U/kg) to fasted rats. The hormonal effect was not further enhanced by the simultaneous administration of calcium chloride (250 mg Ca/kg) to fasted rats, although calcium administration stimulated regucalcin mRNA expression in the liver. The present study suggests that the expression of hepatic regucalcin mRNA stimulated by refeeding is significantly involved in the action of insulin and/or calcium as stimulating factors.     

Oral administration of antigen does not influence the proliferation and IFN-γ production of responsive CD8+ T cells but enables to establish T cell clones with different lymphokine production profile.

Feeding of a whole casein diet, which abolished the α_s1-casein-specific proliferation and IFN-γ productivity of CD⁴⁺ T cells, did not affect the proliferative response of CD8⁺ T cells with regard to the antigen dose response, cell dose response, kinetics of the proliferation and epitope specificity, as well as IFN-γ production. To assess the characteristics of the CD8⁺ T cells, we established α_s1-casein-specific CD8⁺ T cell clones from both casein-fed and control mice. The established clones produced different amount of IFN-γ and IL-10, and one clone derived from the casein-fed mice produced a remarkable amount of IL-10. The clones from casein-fed mice produced considerable amounts of TGF-β, while those from control mice produced only small amounts. The possible role of CD8⁺ T cells in oral tolerance is discussed. This revised version was published online in June 2006 with corrections to the Cover Date.     

Kinetics and collagenolytic role of eosinophils in chronic gastric ulcer in the rat

 An association between eosinophils and tissue damage has been observed in numerous disorders. However, few reports have addressed the role of infiltrating eosinophils in gastric ulcer healing. The aim of this study was to investigate the kinetics and role of eosinophils infiltrating experimental chronic gastric ulcers in the rat. We developed a monoclonal antibody against human matrix metalloproteinase 1 (MMP1) purified from conditioned culture medium of human skin fibroblasts. Acetic acid-induced gastric ulcers were resected from rats on days 1, 3, 5, 10, 20, 40, and 180 after the days of induction (day 0). Tissue specimens were immunostained with this antibody and examined with an electron microscope. Few eosinophils were observed in the granulation tissue until day 20. By days 40 and 180, MMP1-positive eosinophils had increased in the granulation tissue of open ulcers. Azan staining revealed dispersed collagen fibers around infiltrating eosinophils. In contrast, scars demonstrated few eosinophils in fibrous tissue on days 40 and 180. Eosinophils which express MMP1 infiltrate granulation tissue at the chronic stage of gastric ulceration. The results suggest that eosinophils may play a role in tissue remodeling and deterioration of ulceration. Accepted: 18 March 1997     

Effects of some factors on protoplast formation of a microalga,Prototheca zopfii

The effects of experimental factors on protoplast formation of Prototheca zopfii Kru¨ger in 0.85 m NaCl using Macerozyme R-200 were studied based on a fractional factorial experimental design. The rate of protoplast formation was mainly affected by the incubation temperature and the age of algal cells. The optimal condition for the maximum protoplast yield was determined based on a response surface model. These were: mid-logarithmic phase cells and Macerozyme concentration of 4% at a temperature of 35°C.     

Kinetic parameters and mechanism of active cation transport in HeLa cells as studied by Rb+ influx

On incubation of HeLa cells in chilled isotonic medium, intracellular Na+ (Nac+) increased and K+ (Kc+) decreased with time, reaching steady levels after 3 h. The steady levels varied in parallel with the extracellular cation concentrations ([Na+]e, [K+]e). The cell volumes and the protein and water contents, respectively, of cells kept for 3 h in chilled media of various [Na+]e and [K+]e were not significantly different. Ouabain-sensitive Rb+ influx took place at the initial rate for a certain period which depended on [Na+]c at the beginning of the assays. The existence of two external K+ loading sites per Na+/K+-pump was demonstrated. The affinities of the sites for Rb+ as a congener of K+ were almost the same. Na+e inhibited ouabain-sensitive Rb+ influx competitively, whereas K+ was not inhibitory. Kinetic parameters were determined: the K 1/2 for Rbe+ in the absence of Na+e was 0.16 mM and th Ki for Na+e was 36.8 mM; the K 1/2 for Na+c was 19.5 mM and the Ki for K+c seemed to be extremely large. The rate equation of the ouabain-sensitive Rb+ influx suggests that Na+ and K+ are exchanged alternately through the pump by a binary mechanism.