Identification of a 4-Deoxy-l-erythro-5-hexoseulose Uronic Acid Reductase,FlRed, in an Alginolytic Bacterium Flavobacterium sp. Strain UMI-01

In alginate-assimilating bacteria, alginate is depolymerized to unsaturated monosaccharide by the actions of endolytic and exolytic alginate lyases (EC 4.2.2.3 and EC 4.2.2.11). The monosaccharide is non-enzymatically converted to 4-deoxy-l-erythro-5-hexoseulose uronic acid (DEH), then reduced to 2-keto-3-deoxy-d-gluconate (KDG) by a specific reductase, and metabolized through the Entner–Doudoroff pathway. Recently, the NADPH-dependent reductase A1-R that belongs to short-chain dehydrogenases/reductases (SDR) superfamily was identified as the DEH-reductase in Sphingomonas sp. A1. We have subsequently noticed that an SDR-like enzyme gene, flred, occurred in the genome of an alginolytic bacterium Flavobacterium sp. strain UMI-01. In the present study, we report on the deduced amino-acid sequence of flred and DEH-reducing activity of recombinant FlRed. The deduced amino-acid sequence of flred comprised 254 residues and showed 34% amino-acid identities to that of A1-R from Sphingomonas sp. A1 and 80%–88% to those of SDR-like enzymes from several alginolytic bacteria. Common sequence motifs of SDR-superfamily enzymes, e.g., the catalytic tetrad Asn-Lys-Tyr-Ser and the cofactor-binding sequence Thr-Gly-x-x-x-Gly-x-Gly in Rossmann fold, were completely conserved in FlRed. On the other hand, an Arg residue that determined the NADPH-specificity of Sphingomonas A1-R was replaced by Glu in FlRed. Thus, we investigated cofactor-preference of FlRed using a recombinant enzyme. As a result, the recombinant FlRed (recFlRed) was found to show high specificity to NADH. recFlRed exhibited practically no activity toward variety of aldehyde, ketone, keto ester, keto acid and aldose substrates except for DEH. On the basis of these results, we conclude that FlRed is the NADH-dependent DEH-specific SDR of Flavobacterium sp. strain UMI-01.     

Mechanism of the rice hull‐induced germination of Monochoria vaginalis seeds in darkness

The seeds of Monochoria vaginalis require light to germinate. However, they are able to germinate in darkness in the presence of rice hulls. The mechanism of this phenomenon was investigated in this study, in which only the unsterilized seeds of Monochoria were induced to germinate by the presence of a rice hull extract. The rice hull extract was able to be replaced by either a mixture of amino acids and phosphate or a yeast extract. The culture media in which germination was observed always showed turbidity, indicating the propagation of bacteria, which were identified as Bacillus sp., Pedobacter sp., Pantoea sp. and Sphingomonas sp. Treatment with the individual bacterial species or combinations of these bacteria induced Monochoria seed germination when added to the media containing the rice hull extract. It was concluded that the rice hull extract accelerates the propagation of bacteria, which in turn digest the seed coat of Monochoria, facilitating its germination.     

Effect of glimepiride and nateglinide on serum insulin and glucose concentration in healthy cats

Glimepiride and nateglinide are two common oral hypoglycemic agents currently being used with humans suffering from Type 2 diabetes mellitus. Neither drug has been tested with cats thus far and it is currently unknown whether either of these drugs exert any effect in cats or not. The objective of this study was to determine the effect of glimepiride and nateglinide on glucose and insulin responses in healthy control cats, in order to determine their potential use in diabetic cats. The intravenous glucose tolerance tests was carried out since it is an excellent test for evaluating pancreatic β-cell function for insulin secretion. Alterations in the insulin secretion pattern can be perceived as the earliest sign of β-cell dysfunction in many species, including cats. Nateglinide demonstrated a quick action/short duration type effect with serum glucose nadiring and insulin response peaking at 60 and 20 minutes, respectively. Alternatively, glimepiride is medium-to-long acting with serum glucose nadiring and insulin response peaking at 180 minutes and 60 minutes, respectively. Nateglinide’s potency was evident allowing it to induce a 1.5–2 higher preliminary insulin peak (3.7?±?1.1 pg/ml) than glimepiride’s (2.5?±?0.1 pg/ml), albeit only for a short period of time. Because glimepiride and nateglinide have a shared mode of action, no significant differences in overall glucose AUC_0-360min (24,435?±?2,940 versus 24,782?±?2,354 mg min/dl) and insulin AUC_0-360min (410?±?192 versus 460?±?159) in healthy control cats were observed. These findings may provide useful information when choosing a hypoglycemic drug suited for the treatment of diabetic cats depending on the degree of diabetes mellitus the cat is suffering from.     

Recent advances in the high-density rotifer culture in Japan

The success of rapidly growing aquaculture industry depends on the steady supply of fish seeds. Appropriate food for initial larval stages is critical for mass scale fish seed production. Live food found better over artificial food for fish larvae culture. Rotifers have been found to be the best live food for feeding fish larvae in early life stage. Attempts have been made to develop viable techniques for the production of rotifer through batch, continuous, and semi-continuous culture methods. In order to feed increased number of fish larvae, rotifer need to be cultured under high-density method. Various efforts have been made for increasing culture density of rotifer. In Japan, stable high-density culture of rotifer has been developed in commercial scale at a rate of 20,000–30,000 ind. ml^?1. Later on, ultra-high-density rotifer culture (160,000 ind. ml^?1) was found successful, which can fulfill the increased demand for rotifer as fish larval food. Furthermore, a scope of alternative use of rotifer can be explored. The development of the high-density rotifer culture method in Japan has been reviewed. The considerations of the associated nutritional requirements, microbial aspects, and prospects of high-density culture have been discussed.     

Effects of β‐carotene‐enriched dry carrots on β‐carotene status and colostral immunoglobulin in β‐carotene‐deficient Japanese Black cows

Data from 18 β‐carotene‐deficient Japanese Black cows were collected to clarify the effects of feeding β‐carotene‐enriched dry carrots on β‐carotene status and colostral immunoglobulin (Ig) in cows. Cows were assigned to control or carrot groups from 3 weeks before the expected calving date to parturition, and supplemental β‐carotene from dry carrots was 138 mg/day in the carrot group. Plasma β‐carotene concentrations in the control and carrot groups at parturition were 95 and 120 μg/dL, and feeding dry carrots slightly improved plasma β‐carotene at parturition. Feeding dry carrots increased colostral IgA concentrations in cows and tended to increase colostral IgG₁, but colostral IgM, IgG₂, β‐carotene and vitamin A were not affected by the treatment. Feeding dry carrots had no effects on plasma IgG₁, IgA and IgM concentrations in cows, but plasma IgG₁ concentrations decreased rapidly from 3 weeks before the expected calving date to parturition. These results indicate that feeding β‐carotene‐enriched dry carrots is effective to enhance colostral IgA and IgG₁ concentrations in β‐carotene‐deficient cows.     

Solute diffusion into cell walls in solution-impregnated wood under conditioning process III: effect of relative humidity schedule on solute diffusion into shrinking cell walls

This study has focused on solute diffusing into cell walls in solution-impregnated wood under conditioning, process of evaporating solvent. The purpose of this paper was to clarify the RH- (relative humidity-) schedule that promotes the solute diffusion into shrinking cell walls during conditioning. The wood samples impregnated with a 20 mass% aqueous solution of polyethylene glycol (PEG1540) was conditioned with a temperature of 40?°C to the equilibrium point at the RH where the samples swelled maximally. The samples were subsequently conditioned at 40?°C under the schedules including four ways of RH-decrease steps where the cell walls shrunk. The amount of solute (PEGs) diffused into cell walls during the conditioning logarithmically increased with increasing the number of the RH-decrease steps. This was well explained by the theoretical model that describes the solute diffusion into shrinking cell walls. It is clarified from the model that the RH, or moisture content of the sample, should be decreased as gradually as possible to increase the total amount of diffused solute into shrinking cell walls, and that the amount of diffused solute is smaller for the lower moisture content. The model also suggests that effect of change in RH schedule on change in total amount of diffused solute does not depend on solute diffusivity in the sample under drying in a vacuum over phosphorous pentoxide, and that impregnated wood should be conditioned under natural convection rather than forced convection for promoting the diffusion into shrinking cell walls.     

Winter nitrate uptake by the temperate deciduous tree <Emphasis Type="Italic">Quercus serrata</Emphasis>

Winter nitrogen use in deciduous species is largely uncharacterized. We investigated nitrate uptake in the fine roots of a deciduous oak (Quercus serrata Thunb. ex. Murray). We conducted a ¹⁵N-labeling experiment using saplings of Q. serrata in the winter. During three weeks of labeled nitrate application, the concentration of ¹⁵N in the fine roots increased significantly. The amount of nitrogen absorbed, as nitrate, was 1.16 ± 1.02 mg N g DW⁻¹, equivalent to 7.6 ± 5.8% of the total nitrogen content. Our results indicate that Q. serrata saplings have significant potential for nitrate uptake in the fine roots in midwinter (i.e., in the absence of leaves). Although a significant amount of nitrogen applied as nitrate was accumulated, nitrate concentration in the fine roots remained low during the labeling period. Furthermore, significant nitrate reductase activity was detected. These data suggest that Q. serrata saplings can assimilate nitrate in the fine roots in midwinter.     

Immunohistochemical detection of phosphatidylserine and thrombospondin on denucleating erythroblasts in rat bone marrow

The hypothesis that apoptotic factors play some roles in the denucleation of erythroblasts has been confirmed by the immunohistological detection of both phosphatidylserine and thrombospondin as phagocytosis-inducing factors in general apoptotic events. Both phosphatidylserine and thrombospondin were detected on the surface of cell membrane of mature erythroblasts, while thrombospondin was also detected in more immature erythroblasts. The intensities of their immune reactions increased as the erythroids matured. During denucleation, the positivities of both phosphatidylserine and thrombospondin were restricted on the surface of the cell membrane surrounding the protruding nuclei. Thus, the apoptotic process involves denucleation of erythroblasts and phosphatidylserine, and thrombospondin acts as phagocytosis-inducing factors in the denucleation event.