Review of the East Asian species of the genera Hybrizon Fallén and Ghilaromma Tobias (Hymenoptera: Ichneumonidae: Hybrizontinae)

East Asian species of the genera Hybrizon and Ghilaromma are reviewed. Four species of Hybrizon, H. buccatus (Brébisson 1825), H. ghilarovi Tobias, 1988, H. juncoi (Ceballos 1957) and H. flavofacialis Tobias, 1988 and two species of Ghilaromma, G. orientalis Tobias, 1988 and G. ussuriensis Tobias, 1988, were recognized. H. ghilarovi was recorded from Korea, Japan and China, while H. juncoi was recorded from Korea, for the first time. The specimens recorded from Japan as G. fuliginosi (Wilkinson, 1930) by Watanabe (1984) are referred to G. orientalis herein. This species is newly recorded from Korea and Japan. Keys to East Asian species of Hybrizon and the world species of Ghilaromma are also provided.     

Inducible Formation of Glutamate Dehydrogenase in Rice Plant Roots by the Addition of Ammonia to the Media

The activity of glutamate dehydrogenase (l-glutamate: NAD oxidoreductase, EC 1.4.1.2.; GDH) of rice plants changes in response to the nitrogen source supplied to the culture solution. The activity of NADH-GDH(aminating) in roots is rapidly increased by the addition of ammonia, whereas the activity in shoots is much less affected by nitrogen supply. The activity increased with increasing concentration of ammonia at least up to 14.3 mM. In roots GDH activity was found in both the mitochondrial and soluble fractions. The increase of NADH-GDH activity caused by the ammonia treatment occurs mainly in the latter fraction. The new band with GDH activity was detected on the zymogram of polyacrylamide gel electrophoresis and this inducible enzyme is active with both NAD and NADP. On the other hand, the constitutive enzyme activity active with NAD is also increased by the ammonia treatment. The increase of enzyme activity is prevented by the addition of cycloheximide or chloramphenicol to culture medium. The incorporation of ¹⁴C-leucine(U) into GDH proteins was also studied using polyacrylamide gel electrophoresis. Higher radioactivity was found in induced samples than in non-induced ones. These results show that the increase of GDH activity in roots by ammonia treatment seems to depend on de novo protein synthesis.     

Sulfonamide-based non-alkyne LpxC inhibitors as Gram-negative antibacterial agents

We attempted to optimize sulfonamide-based non-alkyne LpxC inhibitors by focusing on improvements in enzyme inhibitory and antibacterial activity. It was discovered that inhibitors possessing 2-aryl benzofuran as a hydrophobe exhibited good activity. In particular, compound 21 displayed impressive antibacterial activity (E. coli MIC = 0.063 μg/mL, K. pneumoniae MIC = 0.5 μg/mL, and P. aeruginosa MIC = 0.5 μg/mL), and is a promising lead for further exploration as an antibacterial agent.     

The AtXTH28 Gene, a Xyloglucan Endotransglucosylase/Hydrolase, is Involved in Automatic Self-Pollination in Arabidopsis thaliana

Successful automatic self-pollination in flowering plants isdependent on the correct development of reproductive organs.In the stamen, the appropriate growth of the filament, whichlargely depends on the mechanical properties of the cell wall,is required to position the anther correctly close to the stigmaat the pollination stage. Xyloglucan endotransglucosylase/hydrolases(XTHs) are a family of enzymes that mediate the constructionand restructuring of xyloglucan cross-links, thereby controllingthe extensibility or mechanical properties of the cell wallin a wide variety of plant tissues. Our reverse genetic analysishas revealed that a loss-of-function mutation of an ArabidopsisXTH family gene, AtXTH28, led to a decrease in capability forself-pollination, probably due to inhibition of stamen filamentgrowth. Our results also suggest that the role of AtXTH28 inthe development of the stamen is not functionally redundantwith its closest paralog, AtXTH27. Thus, our finding indicatesthat AtXTH28 is specifically involved in the growth of stamenfilaments, and is required for successful automatic self-pollinationin certain flowers in Arabidopsis thaliana.     

Cytosolic acidification leads to Ca mobilization from intracellular stores in single and populational parietal cells and platelets

Regulatory relationship and gain control between cytosolic free Ca²⁺ concentration (Ca_i) and cytosolic pH (pH_i) were evaluated by two different cell types, gastric parietal cells, and blood platelets. Studies were carried out in both single cells and populations of cells, using Ca²⁺-indicative probe fura-2 (1-(2-(5′-carboxyoxazol-2′-yl)-6-aminobenzofuran-5-oxy)-2-(2′-amino-5′-methylphenoxy) ethane-N,N,N′,N′-tetraacetic acid) and pH-indicative probe BCECF (2′,7′-bis(carboxyethyl) carboxyfluorescein). Stimulation of single and populational parietal cells and platelets with gastrin and thrombin, respectively, resulted in an increase in Ca_i. In both populational cell types, an initial change in pH_i during agonist stimulation occurred almost simultaneously with the mobilization of Ca²⁺; an initial transient decrease in pH_i was followed by a slower increase in pH_i above the prestimulation level. When populational platelets were preloaded with the Ca²⁺ chelator BAPTA (1,2-bis(o-aminophenoxy)ethane-N,N,N′,N′tetraacetic acid), the thrombin-induced initial large increase in Ca_i was apparently inhibited, whereas the pH_i decrease induced by thrombin was not altered. This suggests that the initial Ca_i change is not a prerequisite for the pH_i change. The effect of pH_i on Ca_i was examined next. In both single and populational cell types, application of the K⁺-H⁺ ionophore nigericin, which induced a transient decrease in pH_i, led to the release of Ca²⁺ from intracellular stores. In single parietal cells double-labeled with fura-2 and BCECF, a temporal decrease in pH_i preceded the rise in Ca_i after stimulation with nigericin. A decrease in pH_i, and an increase in Ca_i occurred at 1.5 and 4 s, respectively. In single parietal cells, replacement of medium Na⁺ with N-methyl- -glucamine (NMG⁺), which also induced a decrease in pH_i, resulted in repetitive Ca²⁺ spike oscillations. The source of Ca²⁺ utilized for the Ca²⁺ oscillation that was induced by NMG⁺ originated from the agonist-sensitive pool. Thus, several maneuvers, which were capable of decreasing pH_i, led to an increase in Ca_i. Cytosolic acidification may be a part of the trigger for Ca²⁺ mobilization from intracellular stores in both parietal cells and platelets.     

Electron-microscopic study of innervation of smooth muscle cells surrounding collecting tubules of the fish kidney

Summary The fine structure of the collecting tubules of the trout and killifish kidney was studied. These tubules are surrounded by layers of smooth muscle cells which are commonly innervated. The nerve terminals contain synaptic vesicles and, occasionally, a few dense-cored granules as well. Capillaries occur in the connective tissue space between these smooth muscle cells and the collecting tubule. Epithelial cells of the collecting tubules contain abundant mitochondria and a well developed membrane system displaying parallel arrays, and were considered to be actively involved in the transport of materials. In the trout, the collecting tubules contain peculiar cells in addition to regular tubule cells. The fine structure of these peculiar cells is highly reminiscent of that of gill chloride cells. The significance of these findings may be summarized as follows: If the smooth muscles around the collecting tubule contract under neural influence, intratubular pressure may be increased and, thus affect glomerular filtration rate. The contraction of these muscles may also cause the collapse of peritubular capillaries, affecting the transport activity of tubule cells.