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K Haga

Publications and source records attributed to K Haga.

At least 19 recordsLinked to original sources
PubMed2001

Enhancement of the thermophilic stage in cattle waste composting by addition of tofu residue.

The microbial degradation and temperature rise during the composting of a cattle waste and rice straw mixture blended with tofu (soybean curd) residue was investigated using an insulated and unheated in-vessel composter (effective volume, 12 1) and a static pile with passive aeration. The addition of 11% (dry weight basis) of tofu residue shortened the time required for temperature to reach the thermophilic phase and increased the duration of the temperatures above 55 degrees C significantly, but the maximum temperature was not affected by the additive level. As shown by the change in BOD, most of the easily biodegradable matter in the tofu residue was consumed during 12 days of composting. The same results were observed in the temperature profile of the static pile with passive aeration. Tofu residue addition yielded a higher maximum temperature and a nearly two times longer duration of temperatures above 55 degrees C in almost all locations of the pile. The use of tofu residue as a co-composting material would promote thermophilic degradation throughout the entire composting mass.

Animals↗
PubMed2001

Crystal structure of cyclodextrin glucanotransferase from alkalophilic Bacillus sp. 1011 complexed with 1-deoxynojirimycin at 2.0 A resolution.

1-Deoxynojirimycin, a pseudo-monosaccharide, is a strong inhibitor of glucoamylase but a relatively weak inhibitor of cyclodextrin glucanotransferase (CGTase). To elucidate this difference, the crystal structure of the CGTase from alkalophilic Bacillus sp. 1011 complexed with 1-deoxynojirimycin was determined at 2.0 A resolution with the crystallographic R value of 0.154 (R(free) = 0.214). The asymmetric unit of the crystal contains two CGTase molecules and each molecule binds two 1-deoxynojirimycins. One 1-deoxynojirimycin molecule is bound to the active center by hydrogen bonds with catalytic residues and water molecules, but its binding mode differs from that expected in the substrate binding. Another 1-deoxynojirimycin found at the maltose-binding site 1 is bound to Asn-667 with a hydrogen bond and by stacking interaction with the indole moiety of Trp-662 of molecule 1 or Trp-616 of molecule 2. Comparison of this structure with that of the acarbose-CGTase complex suggested that the lack of stacking interaction with the aromatic side chain of Tyr-100 is responsible for the weak inhibition by 1-deoxynojirimycin of the enzymatic action of CGTase.

1-Deoxynojirimycin↗
PubMed2000

Differential expression and regulation of K(+) channels in the maize coleoptile: molecular and biophysical analysis of cells isolated from cortex and vasculature.

UNLABELLED: Recently, two K(+) channel genes, ZMK1 and ZMK2, were isolated from maize coleoptiles. They are expressed in the cortex and vasculature, respectively. Expression in Xenopus oocytes characterized ZMK1 as an inwardly rectifying K(+) channel activated by external acidification, while ZMK2 mediates voltage-independent and proton-inhibited K(+) currents. In search of the related gene products in planta, we applied the patch-clamp technique to protoplasts isolated from the cortex and vasculature of Zea mays coleoptiles and mesocotyls. In the cortex, a 6-8 pS K(+) channel gave rise to inwardly rectifying K(+) currents. Like ZMK1, this channel was activated by apoplastic acidification. In contrast, protoplasts from vascular tissue expressing the sucrose transporter ZmSUT1 were dominated by largely voltage-independent K(+) currents with a single-channel conductance of 22 pS. The pronounced sensitivity to the extracellular protons Ca(2+), Cs(+) and Ba(2+) is reminiscent of ZMK2 properties in oocytes. Thus, the dominant K(+) channels in cortex and vasculature most likely represent the gene products of ZMK1 and ZMK2. Our studies on the ZMK2-like channels represent the first in planta analysis of a K+ channel that shares properties with the AKT3 K(+) channel family. KEYWORDS: K(+) channel, voltage-independent, proton block, maize coleoptile.

Cotyledon↗
PubMed2000

Crystal structure of alkalophilic asparagine 233-replaced cyclodextrin glucanotransferase complexed with an inhibitor, acarbose, at 2.0 A resolution.

The product specificity of cyclodextrin glucanotransferase (CGTase) from alkalophilic Bacillus sp. #1011 is improved to near-uniformity by mutation of histidine-233 to asparagine. Asparagine 233-replaced CGTase (H233N-CGTase) no longer produces alpha-cyclodextrin, while the wild-type CGTase from the same bacterium produces a mixture of predominantly alpha-, beta-, and gamma-cyclodextrins, catalyzing the conversion of starch into cyclic or linear alpha-1,4-linked glucopyranosyl chains. In order to better understand the protein engineering of H233N-CGTase, the crystal structure of the mutant enzyme complexed with a maltotetraose analog, acarbose, was determined at 2.0 A resolution with a final crystallographic R value of 0.163 for all data. Taking a close look at the active site cleft in which the acarbose molecule is bound, the most probable reason for the improved specificity of H233N-CGTase is the removal of interactions needed to form a compact ring like a-cyclodextrin.

Acarbose↗
PubMed2000

[Delayed emesis induced by the chemotherapeutic agent doxorubicin hydrochloride in dogs].

The occurrence of delayed emesis induced 24 h after the administration of a non-platina chemotherapeutic agent, doxorubicin hydrochloride (doxorubicin), as well as behaviors such as feeding, drinking and defecation were examined in dogs. A single intravenous administration of 2 mg/kg doxorubicin induced emesis within 24 h of administration in some dogs, while delayed emesis was observed 24 h after administration in all dogs. This delayed emesis emerged strongly at day 3 or 4 and decreased at day 5. Hypophagia, the decreased frequency of drinking and the increased frequency of defecation were induced shortly after delayed emesis. Twenty-four hours after the administration of doxorubicin, a daily dose of 0.3 and 1 mg/kg/day, p.o. azasetron, a 5-HT3 antagonist, was administered for 4 days. Doxorubicin-induced delayed emesis was observed to decrease by about 30 and 50%, respectively. This result suggests that 5-HT3 receptors play a role in the mechanism of delayed emesis. Azasetron was found to improve the increased frequency of defecation, but exerted no obvious effect on hypophagia or on the decreased frequency of drinking. Taken together, we suggest that doxorubicin-induced emesis in dogs is a useful method to study further the mechanisms of delayed emesis and to investigate novel therapeutic agents against delayed emesis.

Animals↗
PubMed1999

Synthesis and pharmacological evaluation of carboxamide derivatives as selective serotoninergic 5-HT(4) receptor agonists.

A number of new carboxamide derivatives were synthesized. The affinity of these compounds for the serotoninergic 5-HT(4) receptor was evaluated by use of radioligand-binding techniques. The agonistic activity was evaluated as the contractile effect of the ascending colon isolated from guinea-pigs. Among these compounds, 4-amino-5-chloro-2-methoxy-N-[1-[2-[(methylsulfonyl)amino]ethly]-4-piperidinylmethyl]benzamide (24) showed a high affinity for the 5-HT(4) receptor (Ki = 9.6 nM). Compound 24 displayed a higher affinity for 5-HT(4) receptors than the other receptors, including, 5-HT(3) and dopamine D(2) receptors. In addition, compound 24 was confirmed to be a potent 5-HT(4) receptor agonist (ED(50) = 7.0 nM). An interaction model between compound 24 and 5-HT(4) receptor was proposed.

Journal Article↗
PubMed1999

Auxin-induced K+ channel expression represents an essential step in coleoptile growth and gravitropism.

Auxin-induced growth of coleoptiles depends on the presence of potassium and is suppressed by K+ channel blockers. To evaluate the role of K+ channels in auxin-mediated growth, we isolated and functionally expressed ZMK1 and ZMK2 (Zea mays K+ channel 1 and 2), two potassium channels from maize coleoptiles. In growth experiments, the time course of auxin-induced expression of ZMK1 coincided with the kinetics of coleoptile elongation. Upon gravistimulation of maize seedlings, ZMK1 expression followed the gravitropic-induced auxin redistribution. K+ channel expression increased even before a bending of the coleoptile was observed. The transcript level of ZMK2, expressed in vascular tissue, was not affected by auxin. In patch-clamp studies on coleoptile protoplasts, auxin increased K+ channel density while leaving channel properties unaffected. Thus, we conclude that coleoptile growth depends on the transcriptional up-regulation of ZMK1, an inwardly rectifying K+ channel expressed in the nonvascular tissue of this organ.

Animals↗
PubMed1999

Development of poorly differentiated adenocarcinoma and carcinoid due to long-term Helicobacter pylori colonization in Mongolian gerbils.

A Mongolian gerbil model was used to clarify whether long-term colonization by Helicobacter pylori is an important risk factor for the development of gastric cancer. Fifty-nine gerbils (3 controls and 56 gerbils inoculated with H. pylori) were killed at various times (average, 23 months) more than 12 months after H. pylori inoculation. In the H. pylori-inoculated group, poorly differentiated adenocarcinoma was observed in the pylorus of 1 gerbil, and carcinoid was observed in the fundus of the stomach in 18 gerbils. No lesions were found in the stomachs of the 3 control gerbils. The results imply that long-term colonization by H. pylori is an important risk factor for the development of gastric adenocarcinoma and carcinoid.

Adenocarcinoma↗
PubMed1999

A mutation in the 3-phosphoglycerate kinase gene allows anaerobic growth of Bacillus subtilis in the absence of ResE kinase.

The Bacillus subtilis ResD-ResE two-component signal transduction system is essential for aerobic and anaerobic respiration. A spontaneous suppressor mutant that expresses ResD-controlled genes and grows anaerobically in the absence of the ResE histidine kinase was isolated. In addition, aerobic expression of ResD-controlled genes in the suppressed strain was constitutive and occurred at a much higher level than that observed in the wild-type strain. The suppressing mutation, which mapped to pgk, the gene encoding 3-phosphoglycerate kinase, failed to suppress a resD mutation, suggesting that the suppressing mutation creates a pathway for phosphorylation of the response regulator, ResD, which is independent of the cognate sensor kinase, ResE. The pgk-1 mutant exhibited very low but measurable 3-phosphoglycerate kinase activity compared to the wild-type strain. The results suggest that accumulation of a glycolytic intermediate, probably 1, 3-diphosphoglycerate, is responsible for the observed effect of the pgk-1 mutation on anaerobiosis of resE mutant cells.

Aerobiosis↗
PubMed1998

GTP-binding-protein-coupled receptor kinase 2 (GRK2) binds and phosphorylates tubulin.

Tubulin was found to bind to a glutathione S-transferase fusion protein containing the carboxy-terminal domain of GTP-binding-protein-coupled receptor kinase 2 (GRK2) (residues 467-689), which is known to contain a pleckstrin homology site and to bind GTP-binding protein betagamma subunits. The binding of tubulin to the fusion protein was not affected by GTP-binding protein betagamma subunits, indicating that tubulin and betagamma subunits bind GRK2 independently. Western-blotting analysis with anti-GRK2 Ig indicated that GRK2 was copurified with tubulin through the polymerization-depolymerization procedure. Tubulin was phosphorylated by GRK2, in contrast with the facts that the known substrates of GRK2 are restricted to activated forms of GTP-binding-protein-coupled receptors and that tubulin is a poor substrate for most kinases. GRK2 did not phosphorylate microtubule-associated proteins (MAPs), under conditions where MAPs were well phosphorylated by endogenous kinases copurified with tubulin. The Km for tubulin was estimated to be 3 microM, and 1.3 mol phosphate/tubulin dimer was incorporated. The phosphorylation of tubulin was stimulated by betagamma subunits and agonist-bound muscarinic receptors. Phosphorylated tubulin could be polymerized into microtubules, and polymerized tubulin was also phosphorylated by GRK2.

Animals↗
PubMed1998

Auxin-growth relationships in maize coleoptiles and pea internodes and control by auxin of the tissue sensitivity to auxin

Growth of a zone of maize (Zea mays L.) coleoptiles and pea (Pisum sativum L.) internodes was greatly suppressed when the organ was decapitated or ringed at an upper position with the auxin transport inhibitor N-1-naphthylphthalamic acid (NPA) mixed with lanolin. The transport of apically applied 3H-labeled indole-3-acetic acid (IAA) was similarly inhibited by NPA. The growth suppressed by NPA or decapitation was restored by the IAA mixed with lanolin and applied directly to the zone, and the maximal capacity to respond to IAA did not change after NPA treatment, although it declined slightly after decapitation. The growth rate at IAA saturation was greater than the rate in intact, nontreated plants. It was concluded that growth is limited and controlled by auxin supplied from the apical region. In maize coleoptiles the sensitivity to IAA increased more than 3 times when the auxin level was reduced over a few hours with NPA treatment. This result, together with our previous result that the maximal capacity to respond to IAA declines in pea internodes when the IAA level is enhanced for a few hours, indicates that the IAA concentration-response relationship is subject to relatively slow adaptive regulation by IAA itself. The spontaneous growth recovery observed in decapitated maize coleoptiles was prevented by an NPA ring placed at an upper position of the stump, supporting the view that recovery is due to regenerated auxin-producing activity. The sensitivity increase also appeared to participate in an early recovery phase, causing a growth rate greater than in intact plants.

Journal Article↗
PubMed1997

The complete genome sequence of the gram-positive bacterium Bacillus subtilis.

Bacillus subtilis is the best-characterized member of the Gram-positive bacteria. Its genome of 4,214,810 base pairs comprises 4,100 protein-coding genes. Of these protein-coding genes, 53% are represented once, while a quarter of the genome corresponds to several gene families that have been greatly expanded by gene duplication, the largest family containing 77 putative ATP-binding transport proteins. In addition, a large proportion of the genetic capacity is devoted to the utilization of a variety of carbon sources, including many plant-derived molecules. The identification of five signal peptidase genes, as well as several genes for components of the secretion apparatus, is important given the capacity of Bacillus strains to secrete large amounts of industrially important enzymes. Many of the genes are involved in the synthesis of secondary metabolites, including antibiotics, that are more typically associated with Streptomyces species. The genome contains at least ten prophages or remnants of prophages, indicating that bacteriophage infection has played an important evolutionary role in horizontal gene transfer, in particular in the propagation of bacterial pathogenesis.

Bacillus subtilis↗
PubMed1997

Sequence analysis of a 25-kb segment in the 17 degrees-19 degrees region of the Bacillus subtilis chromosome containing ada locus.

As a part of the Bacillus subtilis genome sequencing project, we have determined a 25-kb sequence covering the 17 degrees-19 degrees region. This region contains 26 complete open reading frames (ORFs) including the alkA and adaA/B operon, which encode genes for adaptive response to DNA alkylation. A homology search for the newly identified 21 ORFs revealed that 4 of them exhibit a significant similarity to known proteins, e.g., methicillin-resistant Staphylococcus aureus (MRSA) protein homolog, proteins involved in chloramphenicol resistance, glucosamine synthase and an ABC transporter protein. The remaining 17 ORFs did not show any significant sequence similarities to known gene products in the database.

Bacillus subtilis↗
PubMed1997

Sequence analysis of a 45-kb segment in the 19 degrees-23 degrees region of the Bacillus subtilis chromosome containing glpT and mpr loci.

The nucleotide sequence of a 45,137-bp segment covering the 19 degrees and 23 degrees region in the 360 degrees map of the Bacillus subtilis genome was determined. This region contained 45 open reading frames (ORFs) including 7 which corresponded to the products of genes with known functions that had been previously sequenced. The known genes were: glpT and glpQ for glycerol utilization pathway; purT for a part of the purine synthesis pathway; mpr for an extracellular metalloprotease; pss and psd for the parts of the phospholipid synthesis pathway; and gltP for a glutamine transporter. Deduced amino acid sequences of the 22 newly identified ORFs showed significant homologies to known gene products in the database such as a Methicillin-resistant Staphylococcus aureus (MRSA) gene which is related to drug resistance, a two-component response regulator, a series of amino acid permeases, transcriptional regulators, beta-lactamase, the phosphotransferase system (PTS) enzyme II for sugar uptake, and the eukaryotic ECA39 gene which is associated with cancer and apoptosis, etc. The remaining 16 ORFs did not show any significant sequence similarities to known gene products in the database.

Animals↗
PubMed1997

Ca2+-dependent inhibition of G protein-coupled receptor kinase 2 by calmodulin.

Agonist- or light-dependent phosphorylation of muscarinic acetylcholine receptor m2 subtypes (m2 receptors) or rhodopsin by G protein-coupled receptor kinase 2 (GRK2) was found to be inhibited by calmodulin in a Ca2+-dependent manner. The phosphorylation was fully inhibited in the absence of G protein betagamma subunits and partially inhibited in the presence of betagamma subunits. The dose-response curve for stimulation by betagamma subunits of the m2 and rhodopsin phosphorylation was shifted to the higher concentration of betagamma subunits by addition of Ca2+-calmodulin. The phosphorylation by GRK2 of a glutathione S-transferase fusion protein containing a peptide corresponding to the central part of the third intracellular loop of m2 receptors (I3-GST) was not affected by Ca2+-calmodulin in the presence or absence of betagamma subunits, but the agonist-dependent stimulation of I3-GST phosphorylation by an I3-deleted m2 receptor mutant in the presence of betagamma subunits was suppressed by Ca2+-calmodulin. These results indicate that Ca2+-calmodulin does not directly interact with the catalytic site of GRK2 but inhibits the kinase activity of GRK2 by interfering with the activation of GRK2 by agonist-bound m2 receptors and G protein betagamma subunits. In agreement with the assumption that GRK2 activity is suppressed by the increase in intracellular Ca2+, the sequestration of m2 receptors expressed in Chinese hamster ovary cells was found to be attenuated by the treatment with a Ca2+ ionophore, A23187.

Animals↗
PubMed1997

High affinity binding of azasetron hydrochloride to 5-hydroxytryptamine3 receptors in the small intestine of rats.

The binding affinity of azasetron hydrochloride (azasetron) for the 5-hydroxytryptamine3 (5-HT3) receptor in a tissue preparation of rat small intestine was investigated by using [3H]granisetron as a radioligand. Scatchard analysis of specific [3H]granisetron binding revealed a single population of saturable binding sites in the tissue preparation. At this site, azasetron was concentration-dependently competitive with [3H]granisetron, and it inhibited the specific [3H]granisetron binding with a Ki value of 0.33 nM. Azasetron has a high affinity for 5-HT3 receptor in the gastrointestinal organ, the very site of its antiemetic action against chemotherapy-induced emesis.

Animals↗
PubMed1996

Calcium-bound recoverin targets rhodopsin kinase to membranes to inhibit rhodopsin phosphorylation.

In rod photoreceptor cells, Ca2+-bound recoverin associates with disk membranes and inhibits light-dependent phosphorylation of rhodopsin. However, the functional significance of Ca2+-induced membrane association of recoverin has not been fully evaluated. We found that Ca2+-bound recoverin forms a complex with rhodopsin kinase preferentially at the membrane surface. Addition of increasing amounts of membranes promoted the membrane association of recoverin, and remarkably suppressed rhodopsin kinase activity. It was concluded that the Ca2+-recoverin-rhodopsin kinase complex is stabilized by membrane association, leading to effective suppression of the kinase activity.

Animals↗