Med,a cell-surface localized protein regulating a competence transcription factor gene,comK, in Bacillus subtilis

Med was found as a positive regulator for comK, a master regulator for late competence genes. It was found by Western analysis that the ComK level was decreased in a med mutant. Experiments using an alkaline phosphatase fusion with Med and Western analysis of Med were done because a putative lipo-modification signal is found at the N-terminus of Med. The results obtained are consistent with the localization of Med at the cell surface. An implication of the cell-surface localization of Med is discussed in terms of comK regulation.     

Production of mitochondrial DNA transgenic mice using zygotes

Several animal models of human disease, which have been developed by random or targeted modifications of genomic DNA sequences, have furthered our understanding of pathogenesis and the development of therapeutics. However, these models have not facilitated studies on mitochondrial diseases, since modifications to mitochondrial DNA (mtDNA) sequences are not possible using current recombination techniques. Consequently, information on human mitochondrial diseases is relatively sparse, and issues related to mitochondrial pathogenesis and inheritance remain unresolved. Recently, we reported the development of a new technique to generate mice carrying mutant mtDNA from a mouse cell line. In this report, we describe our techniques in detail, with emphasis on the preparation of donor cytoplasts and the micromanipulative procedures for electrofusion of cytoplasts and recipient zygotes. These steps are critically important for the successful introduction of exogenous mtDNA into embryos, and thereby into animals, so that the mutant mtDNA is efficiently propagated in subsequent generations.     

Leptin induces IL-1 receptor antagonist expression in the brain

Fructose has been shown to protect hepatocyte viability during hypoxia or exposure to mitochondrial electron transport inhibitors. We report here that the fructose metabolite D-glyceraldehyde (D-GA) is a good inhibitor of the mitochondrial permeability transition pore (PTP) in isolated rat liver mitochondria. We propose that a substantial portion of the protective effect of fructose on hepatocytes is due to D-GA inhibition of the permeability transition. Aldehydes which are substrates of the mitochondrial aldehyde dehydrogenase (mALDH) afford protection, while poor substrates do not. Protection is prevented by the ALDH inhibitor chloral hydrate. We propose that the NADH/NAD(+) ratio is the key to protection. The aldehydes phenylglyoxal (PGO) and 4-hydroxynonenal (4-HNE), which have previously been shown to inhibit the PTP, apparently function by a different mechanism independent of mALDH activity. Both PGO or 4-HNE are themselves potent inhibitors of ALDH, and their protective effect cannot be blocked by an ALDH inhibitor.     

Putative functions of nucleoside diphosphate kinase in plants and fungi

The putative functions of NDP (nucleoside diaphosphate) kinases from various organisms focusing to fungi and plants are described. The biochemical reactions catalyzed by NDP kinase are as follows. (i) Phosphotransferring activity from mainly ATP to cognate NDPs generating nucleoside triphosphates (NTPs). (ii) Autophosphorylation activity from ATP and GTP. (iii) Protein kinase (phosphotransferring) activity phosphorylating such as myelin basic protein. NDP kinase could function to provide NTPs as a housekeeping enzyme. However, recent works proved possible functions of the NDP kinases in the processes of signal transduction in various organisms, as described below. By use of the extracts of the mycelia of a filamentous fungus Neurospora crassa blue-light irradiation could increase the phosphorylation of a 15-kDa protein, which was purified and identified to be NDP kinase (NDK-1). By use of the etiolated seedlings of Pisum sativum cv Alaska and Oryza sativa red-light irradiation of intact plants increased the phosphorylation of NDP kinase. However, successive irradiation by red–far-red reversed the reaction, indicating that phytochrome-mediated light signals are transduced to the phosphorylation of NDP kinase. NDP kinase localizing in mitochondria is encoded by nuclear genome and different from those localized in cytoplasm. NDP kinase in mitochondria formed a complex with succinyl CoA synthetase. In Spinicia oleraceae two different NDP kinases were detected in the chloroplast, and in Pisum sativum two forms of NDP kinase originated from single species of mRNA could be detected in the choloroplast. However, the function of NDP kinases in the choloroplast is not yet known. In Neurospora crassa a Pro72His mutation in NDP kinase (ndk-1 ^Pro72His ) deficient in the autophosphorylation and protein kinase activity resulted in lacking the light-induced polarity of perithecia. In wild-type directional light irradiation parallel to the solid medium resulted in the formation of the perithecial beak at the top of perithecia, which was designated as light-induced polarity of perithecia. In wild-type in darkness the beak was formed at random places on perithecia, and in ndk ^Pro72His mutant the perithecial beak was formed at random places even under directional light illumination. The introduction of genomic DNA and cDNA for ndk-1 demonstrated that the wild-type DNAs suppressed the mutant phenotype. With all these results except for the demonstration in Neurospora, most of the phenomena are elusive and should be solved in the molecular levels concerning with NDP kinases.     

Overexpression, Purification, and Characterization of Human and Bovine Mitochondrial ATPase Inhibitors: Comparison of the Properties of Mammalian and Yeast ATPase Inhibitors

Mitochondrial ATP synthase (F₁F₀-ATPase) is regulated by an intrinsic ATPase inhibitor protein. In this study, we overexpressed and purified human and bovine ATPase inhibitors and their properties were compared with those of a yeast inhibitor. The human and bovine inhibitors inhibited bovine ATPase in a similar way. The yeast inhibitor also inhibited bovine F₁F₀-ATPase, although the activity was about three times lower than the mammalian inhibitors. All three inhibitors inhibited yeast F₁F₀-ATPase in a similar way. The activities of all inhibitors decreased at higher pH, but the magnitude of the decrease was different for each combination of inhibitor and ATPase. The results obtained in this study show that the inhibitory mechanism of the inhibitors was basically shared in yeast and mammals, but that mammalian inhibitors require unique residues, which are lacking in the yeast inhibitor, for their maximum inhibitory activity. Common inhibitory sites of mammalian and yeast inhibitors are suggested.     

Relationship between adrenomedullin and vasopressin-aquaporin system under general anesthesia

AIM: The roles of adrenomedullin (AM) in body fluid balance under general anesthesia were investigated. METHODS: Time course changes in plasma osmolality, AM, arginine vasopressin (AVP), and urinary aquaporin 2 (AQP2) in 17 patients undergoing abdominal surgery under general anesthesia were examined. RESULTS: Increases in plasma AM levels were observed in parallel with increases in the levels of urinary AQP2/creatinine (Cr) before induction and 90 and 180 min after initiation of anesthesia. Significant correlations between plasma AM and urinary AQP2/Cr (r = 0.62, p < 0.0001) as well as urinary AVP/Cr and AQP2/Cr (r = 0.60, p < 0.0001) were uncovered. Multivariate stepwise analysis identified plasma AM as the critical independent factor affecting urinary AQP2/Cr level. CONCLUSION: A novel correlation of AM and AQP2 which overlays an AVP-AQP2 system may play a key role in fluid homeostasis during general anesthesia.     

Impaired learning with enhanced hippocampal long-term potentiation in PTPdelta-deficient mice

Protein tyrosine phosphatase delta (PTPdelta) is a receptor-type PTP expressed in the specialized regions of the brain including the hippocampal CA2 and CA3, B lymphocytes and thymic medulla. To elucidate the physiological roles of PTPdelta, PTPdelta-deficient mice were produced by gene targeting. It was found that PTPdelta-deficient mice were semi-lethal due to insufficient food intake. They also exhibited learning impairment in the Morris water maze, reinforced T-maze and radial arm maze tasks. Interestingly, although the histology of the hippocampus appeared normal, the magnitudes of long-term potentiation (LTP) induced at hippocampal CA1 and CA3 synapses were significantly enhanced in PTPdelta-deficient mice, with augmented paired-pulse facilitation in the CA1 region. Thus, it was shown that PTPdelta plays important roles in regulating hippocampal LTP and learning processes, and that hippocampal LTP does not necessarily positively correlate with spatial learning ability. To our knowledge, this is the first report of a specific PTP involved in the regulation of synaptic plasticity or in the processes regulating learning and memory.     

Group I intron located in PR protein homologue gene in Youngia japonica

A Youngia japonica strain had a group I intron that was suggested to have been transferred from Protomyces inouyei, a pathogenic fungus of Y. japonica. It was located in the miraculin homologue coding gene by reverse complementation. The deduced amino acid sequence of this miraculin homologue of Y. japonica was similar to the amino acid sequences of tobacco and tomato pathogenesis-related proteins.