A new member of the HCO3(-) transporter superfamily is an apical anion exchanger of beta-intercalated cells in the kidney

The kidneys play pivotal roles in acid-base homeostasis, and the acid-secreting (alpha-type) and bicarbonate-secreting (beta-type) intercalated cells in the collecting ducts are major sites for the final modulation of urinary acid secretion. Since the H(+)-ATPase and anion exchanger activities in these two types of intercalated cells exhibit opposite polarities, it has been suggested that the alpha- and beta-intercalated cells are interchangeable via a cell polarity change. Immunohistological studies, however, have failed to confirm that the apical anion exchanger of beta-intercalated cells is the band 3 protein localized to the basolateral membrane of alpha-intercalated cells. In the present study, we show the evidence that a novel member of the anion exchanger and sodium bicarbonate cotransporter superfamily is an apical anion exchanger of beta-intercalated cells. Cloned cDNA from the beta-intercalated cells shows about 30% homology with anion exchanger types 1-3, and functional expression of this protein in COS-7 cells and Xenopus oocytes showed sodium-independent and 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid-insensitive anion exchanger activity. Furthermore, immunohistological studies revealed that this novel anion exchanger is present on the apical membrane of beta-intercalated cells, although some beta-intercalated cells were negative for AE4 staining. We conclude that our newly cloned transporter is an apical anion exchanger of the beta-intercalated cells, whereas our data do not exclude the possibility that there may be another form of anion exchanger in these cells.     

Strain- and age-dependent loss of sarcoglycan complex in cardiomyopathic hamster hearts and its re-expression by delta-sarcoglycan gene transfer in vivo

We found that 5-S-GAD, an insect-derived antibacterial peptide, inhibited murine osteoclast formation in vitro. We examined the specific time point of the inhibitory action of 5-S-GAD on osteoclast formation and found that it mainly suppressed differentiation of osteoclasts in the middle of the culture period. Using HL60 cells that are able to differentiate into multinucleated macrophage-like cells, we found that 5-S-GAD induced apoptosis of HL60 cells by producing H(2)O(2). Thus, the inhibition of osteoclast formation by 5-S-GAD could be, in part, due to apoptosis of the cells of an osteoclast lineage.     

Balneomonas flocculans gen. nov., sp. nov., a new cellulose-producing member of the alpha-2 subclass of Proteobacteria

A new bacterial strain capable of producing cellulose was isolated from a hot spring. The isolate was Gram-negative, aerobic, and rod-shaped. The optimum temperature for growth was 40-45 degrees C. Methanol, glucose and other common carbohydrates were not utilized as sole growth substrates. Thiosulfate was not oxidized. The G+C content of the DNA was determined to be 64.0 mol%. Comparative 16S rDNA analysis indicated that Bosea thiooxidans and some strains of the genus Methylobacterium were the nearest relatives. The isolate can be distinguished from these relatives by its defectiveness in methanol utilization and thiosulfate oxidation. On the basis of its phenotypic properties and phylogeny, it is proposed that the isolate be designated Balneomonas flocculans gen. nov., sp. nov. The type strain is TFBT (= JCM 11936T, = KCTC 12101T, = IAM 15034T, = ATCC BAA-817T).     

Enhanced calcium absorption in the small intestine by a phytate-removed deamidated soybean globulin preparation

Soybean globulins were deamidated after removing phytate using ion-exchange resins, and then hydrolyzed by digestive enzymes. The phytate-removed deamidated soybean globulins (PrDS) retained high calcium-binding ability even after the hydrolysis by digestive enzymes. PrDS and its hydrolysates enhanced calcium absorption from the small intestine when injected into the small intestine together with a calcium solution.     

Effect of phytate-removal and deamidation of soybean proteins on calcium absorption in the in situ rats

Soybean proteins were deamidated by cation-exchange resins after phytate, the inhibitor for calcium absorption from the small intestine, was removed in order to provide the enhancement function of calcium absorption to soybean proteins. About 92% of the phosphorus was removed from the soybean proteins by anion-exchange-resin treatment, indicating that most of the phytate was removed. About 70% of the acid amide was deamidated by cation-exchange-resin treatment, and phytate-removed and deamidated soybean proteins (PrDS) having high calcium binding properties were obtained. PrDS were hydrolyzed by digestive enzymes and their calcium-binding properties and the enhancement function of the calcium absorption from the small intestine of rats were examined. As a result, PrDS retained their high calcium binding properties even after hydrolysis by digestive enzymes. In situ experiments showed that PrDS and their hydrolysates enhanced the calcium absorption from the intestine.     

Over-expression of the testis-specific gene TSGA10 in cancers and its immunogenicity

The TSGA10 gene was originally isolated in normal testis by differential mRNA display. TSGA10 is located on chromosome 2q11.2 and consists of 19 exons extending over 3 kb. TSGA10 mRNA expression was investigated in normal and malignant tissues using quantitative real-time RT-PCR. It was predominantly expressed in the testis in adult normal tissues. In malignant tissues, TSGA10 was over-expressed in 4 of 20 hepatocellular carcinomas (HCC), 1 of 20 colon cancers, 7 of 20 ovarian cancers, 3 of 20 prostate cancers, 1 of 21 malignant melanomas, and 8 of 21 bladder cancers. Serological analysis revealed that 3 out of 346 patients with various types of cancer possessed antibody against recombinant TSGA10 protein. They included 2 patients with hepatocellular carcinoma and a patient with malignant melanoma.     

Changes in the thermal dissipation and the electron flow in the water-water cycle in rice grown under conditions of physiologically low temperature

Effects of low temperature on chlorophyll (Chl) fluorescence, gas exchange rate, the amounts of xanthophyll cycle pigments (Xp) and the activities of several antioxidant enzymes were examined in the 8th leaf of two rice (Oryza sativa L.) cultivars (japonica and indica types) and rbcS antisense rice. All plants were grown hydroponically at 25/20 degrees C (day/night), and then exposed to 20/17 degrees C (day/night) after full expansion of the 8th leaf, or exposed to either 20/17 degrees C or 15/13 degrees C (day/night) during the expansion of the 8th leaf. All plants exposed to low temperatures showed a decrease in CO(2) assimilation rate without photoinhibition, and increases in the fraction of thermal dissipation in PSII, and in the electron flux through the water-water cycle (WWC) were observed. Although the increase of thermal dissipation was associated with increases in the ratio of carotenoids to Chl, the ratio of Xp to carotenoids and the de-epoxidation state of Xp, the increase of the electron flux of WWC was not accompanied by an increase in the activities of antioxidant enzymes. Such photoprotective responses did not differ between during and after full expansion of the leaf, and did not differ among the three genotypes. Quantitative analyses on the dissipation of excess light energy showed that thermal dissipation makes a larger contribution than WWC. Thus, although low temperature led to a decrease in CO(2) assimilation, rice potentially coped with the excess light energy by increasing the thermal dissipation and the electron flux of WWC under low temperature irrespective of leaf development and genotypes.     

ARC3, a chloroplast division factor, is a chimera of prokaryotic FtsZ and part of eukaryotic phosphatidylinositol-4-phosphate 5-kinase

The arc3 (accumulation and replication of chloroplast) mutant of Arabidopsis thaliana has a small number of abnormally large chloroplasts in the cell, suggesting that chloroplast division is arrested in the mutant and ARC3 has an important role in the initiation of chloroplast division. To elucidate the role of ARC3, first we identified the ARC3 gene, and determined the location of ARC3 protein during chloroplast division because the localization and spatial orientation of such division factors are vital for correct chloroplast division. Sequencing analysis showed that ARC3 was a fusion of the prokaryotic FtsZ and part of the eukaryotic phosphatidylinositol-4-phosphate 5-kinase (PIP5K) genes. The PIP5K-homologous region of ARC3 had no catalytic domain but a membrane-occupation-and-recognition-nexus (MORN) repeat motif. Immunofluorescence microscopy, Western blotting analysis and in vitro chloroplast import and protease protection assays revealed that ARC3 protein was soluble, and located on the outer surface of the chloroplast in a ring-like structure at the early stage of chloroplast division. Prokaryotes have one FtsZ as a gene for division but have no ARC3 counterparts, the chimera of FtsZ and PIP5K, suggesting that the ARC3 gene might have been generated from FtsZ as another division factor during the evolution of chloroplast by endosymbiosis.     

Comparison of pulmonary vascular response to endogenous nitric oxide inhibition in sheep and pigs living at 2,300 m

To compare the role of nitric oxide in an adaptive process to chronic hypoxia, we examined the effects of endogenous nitric oxide synthase inhibition on pulmonary vascular tone in conscious sheep and pigs living at high altitude. Unanesthetized male sheep (n=6) and pigs (n=5), born and residing in the highlands of Qinghai Province, China (2,300–3,000 m a.s.l.) were studied at that altitude. Pulmonary artery pressure (P_pa), pulmonary artery wedge pressure (P_cwp), and cardiac output (CO) were measured. Pulmonary vascular resistance (PVR) was calculated as (P_pa—P_cwp)/CO. Using a climatic chamber, hemodynamic measurements during exposures to atmospheric pressures corresponding to altitudes of 0, 2,300, and 4,500 m a.s.l. were performed with and without NO inhibition, using N^w-nitro-l-argine (NLA; 20 mg kg^–1), a potent stereospecific competitive inhibitor of nitric oxide synthase. P_pa and PVR at baseline (2,300 m) and during hypoxic exposure (4,500 m) were significantly higher in pigs than in sheep. After NLA administration, P_pa increased and CO decreased in both animals, resulting in significantly increased PVR at baseline and during hypoxic exposure. However, there were no significant differences in the percent increase in basal or hypoxic PVR after NLA administration between sheep and pigs. We conclude that augmented endogenous NO production could contribute to the regulation of pulmonary vascular tone at high altitude in sheep and pigs. However, it is unlikely that NO is responsible for the different pulmonary vascular tones between sheep and pigs at basal condition at moderately high altitude.Communicated by G. Heldmaier