A COMPARISON OF VARIABILITY IN UTRICULARIA CORNUTA AND UTRICULARIA JUNCEA

Although Utricularia cornuta Michx. and U. juncea Vahl, sympatric in the southeastern United States, have been considered conspecific by various authors, the present biosystematic approach shows them to be separate species. The taxa are seasonally isolated. While both have the same chromosome number (n = 9), strong internal isolation is apparent since artificial hybrids cannot be produced by standard methods. In Utricularia cornuta the mean values of characters studied quantitatively are much higher than those of U. juncea though the extremes of the ranges may overlap. Utricularia juncea has both cleistogamous flowers and chasmogamous flowers while U. cornuta has only chasmogamous flowers. The flowers are self-fertile and apparently are usually, if not always, self-pollinated, even though they are highly adapted to specialized insect pollinators.     

Characterization and deposition of the proteins in the outermost layer of Bacillus megaterium spore

It was proved that three spore coat proteins of 48, 36, and 22 kDa (P48, P36, and P22) were the components of the outermost layer (OL) of Bacillus megaterium ATCC 12872 spore by analysis of the isolated OL. And it was indicated that these proteins were deposited not by disulfide bond, but by ionic and/or hydrophobic bonds on the spore. Among them, P36 and P22 were expected to be located on the very surface of the spore by immunological analysis. In the OL deficient mutant of B. megaterium ATCC 12872, MAE05, whose spore was lacking in these OL proteins and galactosamine-6-phosphate polymer, both P36 and P22 were present in the mother cell cytoplasm and deposited on the forespores, but they disappeared with the lysis of mother cells. An OL protein-releasing factor having proteolytic activity was detected in the culture supernatant at the late sporulating stage of both the wild-type and the mutant strains. But the factor could not act on the proteins of the mature spores and the forespores at t10 (tn indicates n hr after the end of exponential growth) of the wild-type strain. Moreover, P36 and P22 were found in the spores of a revertant of MAE05 which could form galactosamine-6-phosphate polymer, suggesting that this sugar polymer played the role in protecting the OL proteins against the protease-like substance after the deposition.     

Mechanism of polymorphonuclear leukocytes accumulation examined using inhibitors of complement and arachidonic acid cascade in rats treated with OK-432

When the streptococcal preparation OK-432 was intraperitoneally injected for the treatment of carcinomatous peritonitis, antitumor polymorphonuclear leukocytes (PMNs) accumulated in the peritoneal cavity. We examined the mechanism of this PMN accumulation using an in vivo system in rats. FUT-175, EDTA and K76 inhibited C5a generation by OK-432 in vitro, but EGTA, prednisolone and inhibitors of arachidonic acid cascade did not. In in vivo experiments, EDTA, FUT-175, antirat C3 serum and K76 reduced the accumulation of PMNs onto filter membranes, when these reagents were reacted with OK-432 for 3 h through filter membranes placed on the turned rat peritoneum. EGTA failed to inhibit PMN accumulation. Prednisolone, indomethacin, OKY046 and AA861 inhibited PMN accumulation in a dose-dependent manner. These inhibitions of PMN accumulation were confirmed by histological examination. It was concluded that complement-derived chemotactic factor C5a generated by OK-432 induced PMN accumulation in association with chemotactic arachidonic acid metabolites.     

Further Evidence for Inactivation of Fructose-1,6-bisphosphatase at the Beginning of SO2 Fumigation. Increase in Fructose-1,6-bisphosphate and Decrease in Fructose-6-phosphate in SO2-Fumigated Spinach Leaves

The substrate level of the photosynthetic reductive pentosephosphate cycle in spinach leaves during SO₂ fumigation wassurveyed. At the beginning of SO₂ fumigation, fructose-1,6-bisphosphateincreased and fructose-6-phosphate decreased, while ribulose-1,5-bisphosphateremained unchanged and 3-phosphoglyceric acid rapidly decreased.These results suggested that the inhibition of photosynthesisin spinach leaves with SO₂ might be due to inactivation of fructose-1,6-bisphosphatase. (Received May 26, 1982; Accepted September 27, 1982)     

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.     

Role of Guanine Nucleotide Exchange Factor-H1 in Complement-mediated RhoA Activation in Glomerular Epithelial Cells

Visceral glomerular epithelial cells (GEC), also known as podocytes, are vital for the structural and functional integrity of the glomerulus. The actin cytoskeleton plays a central role in maintaining GEC morphology. In a rat model of experimental membranous nephropathy (passive Heymann nephritis (PHN)), complement C5b-9-induced proteinuria was associated with the activation of the actin regulator small GTPase, RhoA. The mechanisms of RhoA activation, however, remained unknown. In this study, we explored the role of the epithelial guanine nucleotide exchange factor, GEF-H1, in complement-induced RhoA activation. Using affinity precipitation to monitor GEF activity, we found that GEF-H1 was activated in glomeruli isolated from rats with PHN. Complement C5b-9 also induced parallel activation of GEF-H1 and RhoA in cultured GEC. In GEC in which GEF-H1 was knocked down, both basal and complement-induced RhoA activity was reduced. On the other hand, GEF-H1 knockdown augmented complement-mediated cytolysis, suggesting a role for GEF-H1 and RhoA in protecting GEC from cell death. The MEK1/2 inhibitor, U0126, and mutation of the ERK-dependent phosphorylation site (T678A) prevented complement-induced GEF-H1 activation, indicating a role for the ERK pathway. Further, complement induced GEF-H1 and microtubule accumulation in the perinuclear region. However, both the perinuclear accumulation and the activation of GEF-H1 were independent of microtubules and myosin-mediated contractility, as shown using drugs that interfere with microtubule dynamics and myosin II activity. In summary, we have identified complement-induced ERK-dependent GEF-H1 activation as the upstream mechanism of RhoA stimulation, and this pathway has a protective role against cell death.     

Key factors controlling the size, biomass, and sprouting of Japanese alder swamp forest in Kushiro Mire, Hokkaido, Japan

The interrelation among size, biomass, and sprouting of alder trees was studied to extract the most important hydrochemistrical factors controlling the growth of alder forest in Kushiro Mire, northern Japan. The gradient was mostly explained by chemical variables such as pH, ash content, and P₂O₅, which showed strong positive correlation with each other, and secondarily by fluctuation of the water table (WL, i.e., water level range). These variables are more important than other hydrochemical ones, because neutral and turbid flood water replaces acidic mire water and conveys fine sediment with adsorbed phosphorus, which in turn could regulate the pH and amount of phosphorus. Also, the number of sprouts showed negative correlation mainly with tree size and redox potential (Eh), which suggested a flooded environment. Because of this, the size of alder was suppressed by hydrochemical variables; however, alder individuals producing new sprouts were maintained. We conclude that variation in size, biomass, and sprouting of alder was mainly controlled by acidity and phosphorus availability, and was significantly influenced by water fluctuation.