The Lethal Effect of a Benzamide Derivative, 3-Methoxybenzamide, Can Be Suppressed by Mutations within a Cell Division Gene, ftsZ, in Bacillus subtilis

3-Methoxybenzamide (3-MBA), which is known to be an inhibitor of ADP-ribosyltransferase, inhibits cell division in Bacillus subtilis, leading to filamentation and eventually lysis of cells. Our genetic analysis of 3-MBA-resistant mutants indicated that the primary target of the drug is the cell division system involving FtsZ function during both vegetative growth and sporulation.     

Proteome analysis of rice root proteins regulated by gibberellin

To gain an enhanced understanding of the mechanism by which gibberellins （GAs） regulate the growth and development of plants, it is necessary to identify proteins regulated by GA. Proteome analysis techniques have been applied as a direct, effective, and reliable tool in differential protein expressions. In previous studies, sixteen proteins showed differences in accumulation levels as a result of treatment with GA3, uniconazole, or abscisic acid （ABA）, and/or the differences between the GA-deficient semi-dwarf mutant, Tan-ginbozu, and normal cultivars. Among these proteins, aldolase increased in roots treated with GA3, was present at low levels in Tan-ginbozu roots, and decreased in roots treated with uniconazole or ABA. In a root elongation assay, the growth of aldolase-antisense transgenic rice was half of that of vector control transgenic rice. These results indicate that increases in aldolase activity stimulate the glycolytic in the GA-induced growth of roots. In among GA, aldolase, and root growth. pathway and may play an important role this review, we discuss the relationship among GA, aldolase, and root growth.     

Calmodulin and Ca2+/calmodulin-binding proteins are involved in Tetrahymena thermophila phagocytosis

The ciliated protist, Tetrahymena thermophila, possesses one oral apparatus for phagocytosis, one of the most important cell functions, in the anterior cell cortex. The apparatus comprises four membrane structures which consist of ciliated and unciliated basal bodies, a cytostome where food is collected by oral ciliary motility, and a cytopharynx where food vacuoles are formed. The food vacuole is thought to be transported into the cytoplasm by a deep fiber which connects with the oral apparatus. Although a large number of studies have been done on the structure of the oral apparatus, the molecular mechanisms of phagocytosis in Tetrahymena thermophila are not well understood. In this study, using indirect immunofluorescence, we demonstrated that the deep fiber consisted of actin, CaM, and Ca2+/CaM-binding proteins, p85 and EF-1alpha, which are closely involved in cytokinesis. Moreover, we showed that CaM, p85, and EF-1alpha are colocalized in the cytostome and the cytopharynx of the oral apparatus. Next, we examined whether Ca2+/CaM signal regulates Tetrahymena thermophila phagocytosis, using Ca2+/CaM inhibitors chlorpromazine, trifluoperazine, N-(6-aminohexyl)-1-naphthalenesulfonamide, and N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide HCI. In Tetrahymena, it is known that Ca2+/CaM signal is closely involved in ciliary motility and cytokinesis. The results showed that one of the inhibitors, N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide HCl, inhibited the food vacuole formation rather than the ciliary motility, while the other three inhibitors effectively prevented the ciliary motility. Considering the colocalization of CaM, p85, and EF-1alpha to the cytopharynx, these results suggest that the Ca2+/CaM signal plays a pivotal role in Tetrahymena thermophila food vacuole formation.     

Essential roles of Meltrin beta (ADAM19) in heart development

Morphogenesis of the heart requires development of the endocardial cushion tissue that gives rise to the membranous septa and valves. Here we show that Meltrin beta/ADAM19, a novel metalloprotease-disintegrin, participates in the development of the endocardial cushion. Mice lacking Meltrin beta exhibit ventricular septal defect (VSD) and immature valves, and most of the animals die soon after birth. During development of the endocardial cushion, epithelial-mesenchymal transformation (EMT) of endocardial epithelial cells generates most of the cushion mesenchymes that constitute the main components of the septa and valves. Meltrin beta is expressed in both the epithelia and the mesenchymes of the endocardial cushion. In the absence of Meltrin beta, the cushion is small or thin in the septum-forming region and show poor remodeling of cardiac jelly components; both of these characteristics suggest impaired growth and differentiation of the endocardial cushion. When embryonic fibroblasts are cultured sparsely, Meltrin beta-lacking cells exhibit aberrant ectodomain shedding of type I Neuregulin, one of the ErbB ligands expressed in endocardial cells. These results suggest the necessity of proteolytic regulation of ErbB ligands by Meltrin beta for proper heart development.     

Cold stress-induced calcium-dependent protein kinase(s) in rice (Oryza sativa L.) seedling stem tissues

Ca²⁺-dependent protein kinases (CDPKs) play an important role in plant signal transduction. Protein kinase(s) activities induced by 5°C cold stress in rice (Oryza sativa L.) seedlings were investigated in both leaf and stem tissues in an early (up to 45 min) and late (up to 12 h) response study. The leaf had 37-, 47- and 55-kDa protein kinase activities, and the stem had 37-, 47- and 55-kDa protein kinase activities. A 16-kDa protein showed constitutive kinase activity in the rice seedling leaf and stem. It was further identified that the 47-kDa protein kinase activity induced by cold in both the cytosolic and membrane fractions of the stem was strictly Ca²⁺-dependent. This CDPK activitiy increased in the presence of the Ca²⁺ ionophore A23187 in stem segments, whereas it was decreased by the Ca²⁺ channel blocker, LaCl₃, and the Ca²⁺ chelator, EGTA. The general protein kinase inhibitor, staurosporine, completely inhibited this CDPK activity in vitro, and both W7, a calmodulin antagonist, and H7, a protein kinase C inhibitor, could only partially decrease this activity. The protein phosphatase inhibitor, okadaic acid, increased CDPK activity. This CDPK activity was also induced by salt, drought stress and the phytohormone abscicic acid. Among the 18 rice varieties tested, this cold-induced 47-kDa CDPK activity was stronger in the cold-tolerant varieties than in the sensitive ones. Received: 13 August 1999 / Accepted: 24 January 2000     

Ca2+independent cytotoxicity of Vibrio parahaemolyticus thermostable direct hemolysin (TDH) on Intestine 407, a cell line derived from human embryonic intestine

Abstract The effects of Vibrio parahaemolyticus thermostable direct hemolysin on Intestine 407, a cell line derived from the intestine of human embryo, were investigated. The hemolysin was shown to be cytotoxic to Intestine 407. This cytotoxicity is accompanied by the damage of plasma membrane and lysosomes, as well as cellular degeneration in the form of large transparent blebs. Although an increase in cytosolic free Ca²⁺ due to the influx of extracellular Ca²⁺ was observed in cells treated with thermostable direct hemolysin, it was found to be irrelevant to any of the above effects. These results suggest that the effects of thermostable direct hemolysin observed in this study on Intestine 407 are not mediated by Ca²⁺-dependent pathways.     

Plant regeneration on cultured root segments of Cephaelis ipecacuanha A. Richard

Summary Simple one step micropropagation system for Cephaelis ipecacuanha A. Richard was developed using root cultures grown in vitro. Adventitious shoots were directly formed on the cut end of root segments without callus formation, on phytohormone-free B5 solid medium in the dark. When the shoots attached with root segments were further cultured under 16 h light / 8 h dark, they developed into plantlets, which could be transplanted to soil. The regenerated plants grew well in a greenhouse with showing normal appearance and accumulated alkaloids. The influence of auxin on adventitious shoot formation was also investigated.Abbreviations MS Murashige-Skoog (Murashige and Skoog 1962) - 1/2 MS half strength MS - B5 Gamborg B5(Gamborg et al. 1968) - WP woody plant (Lloyd and McCowm 1980) - RC root culture (Thomas and Davey 1982) - HF phytohormone free - IAA indole-3-acetic acid - NAA 1-naphtaleneacetic acid - TIBA 2,3,5-triiodobenzoic acid - 2,4,6-T 2,4,6-trichlorophenoxyacetic acid - SEM scanning electron microscopy - C.V. coefficient of variation     

Recognition by restriction endodeoxyribonuclease EcoRI of octadeoxyribonucleotides containing modified sugar and base moieties

The modified base and sugar moieties, 8-oxo-7,8-dihydroadenine (HO8A),8-methoxyadenine (MeO8A),8-methoxyguanine (MeO8G) and 9-[(2-hydroxy-1-(hydroxymethyl)-ethoxy)-methyl]-adenine (acA), were chemically introduced in place of the adenine or guanine in the octa-deoxyribonucleotides [d(GGAATTCC)] containing recognition sequence of Eco RI. to the regular DNA-fragment.     

A novel low-density lipoprotein with large amounts of phospholipid found in the egg yolk of crustacea sand crayfish Ibacus ciliatus: its function as vitellogenin-degrading proteinase.

Low-density lipoprotein (LDL) with large amounts of phospholipid but not triacylglycerol was isolated from the egg yolk of crustacea sand crayfish Ibacus ciliatus as well as lipovitellin. LDL possessed vitellogenin-degrading proteinase activity. Hemolymph vitellogenin was degraded by incubating with LDL at pH 4.5 for 72 hr at 35 degrees C and apolipoprotein profiles of vitellogenin degraded by LDL were very similar to those of lipovitellin in the egg.