Enhanced degradation of gamma-irradiated lignocelluloses by a new xylanolytic Flavobacterium sp. isolated from soil

An extracellular chitosanase produced by Rhodotorula gracilis CFR-1 that catalyses a limited degradation of chitosan with no detectable generation of glucosamine or reducing groups was identified. Ultracentrifugation, polyacrylamide gel electrophoresis and gel permeation studies suggest that chitosan of average molecular mass 36000 Da was reduced by the enzymic catalysis to nearly one-fourth this size without further hydrolysis of the products. The enzyme, produced constitutively by this yeast, was partially purified and some of its properties were studied.     

Antidiabetic effect of a glycoside of pelargonidin isolated from the bark of Ficus bengalensis Linn.

The antidiabetic effect of a dimethoxy derivative of perlargonidin 3-O-alpha-L rhamnoside (250 mg/kg, single dose study and 100 mg/kg/day long term study) isolated from the bark of Ficus bengalensis Linn. has been compared with that of glibenclamide (2 mg/kg and 0.5 mg/kg/day respectively) in moderately diabetic rats. The single dose glycoside treatment decreased fasting blood glucose by 19% and improved glucose tolerance by 29%. The corresponding effects of glibenclamide were 25% and 66% respectively over the control values. On one-month treatment the fasting blood glucose levels went down almost to half of the pretreatment levels in both the groups and their glucose tolerance improved by 41% in glibenclamide group and by 15% in glycoside treated group. Urine sugar decreased to traces in both the groups and they appeared healthy. In vitro studies showed that insulin secretion by beta-cells was more in presence of the pelargonidin derivative than in presence of a leucocyanidin derivative, reported to be a good anti-diabetic agent.     

Purification and partial characterization of two azoreductases from Shigella dysenteriae Type 1

Two azoreductases (I and II) were purified to homogeneity from extracts of Shigella dysenteriae (type 1). Azoreductase I was a dimer of identical subunits of M(r) 28,000, whereas azoreductase II was a monomer of 11,000 M(r). Both were flavoproteins, each containing 1 mol of FMN per mol enzyme. Both NADH and NADPH functioned as electron donors for the azoreductases. Azoreductase I used Ponceau SX, Tartrazine, Amaranth and Orange II as substrates. Azoreductase II utilized all the dyes except Amaranth.     

Embryology ofMalaxis saprophyta,with comments on the systematic position ofMalaxis (Orchidaceae)

InMalaxis saprophyta, anther wall development corresponds to the Monocotyledonous type. The uninucleate tapetum is of secretory type and the endothecium develops U- and V-shaped thickenings on the inner tangential and radial walls. Cytokinesis is simultaneous; tetrahedral, isobilateral and T-shaped tetrads are formed which are compactly aggregated in pollinia. At anthesis the microspore tetrads are 2-celled. The ovule is anatropous, bitegmic and both integuments are dermal in origin. A single hypodermal cell develops directly into a megaspore mother cell. Embryo sac development is predominantly monosporic and less often bisporic. Irrespective of the type of development, the mature embryo sac is 6-nucleate. Although double fertilization occurs, the primary endosperm nucleus degenerates. Embryogeny is of the Onagrad type. The mature embryo lacks differentiation into cotyledon, plumule and radicle. The reticulate seed coat is formed entirely by the outer layer of outer integument. There are three sterile and three fertile valves in the ovary. Although initially parenchymatous, the entire three sterile valves in the ovary and the upper half of the three fertile valves become sclerified after fertilization. The embryological characters support the disputed systematic position ofMalaxis within subtribeMalaxidinae ofEpidendreae.     

Inhibition of red light-induced seed germination by indole-3-acetic acid inHygrophila auriculata

Seed germination inHygrophila auriculata (Schumach.) Haines was found to be under phytochrome control. Exogenous indole-3-acetic acid (IAA) application at concentrations greater than 1×10^–6 M inhibited germination in the dark, as well as in the light. Red light-induced radicle growth, prior to radicle protrusion through seed coverings and measured as an angle formed by the radicle with the seed axis, was found to be inhibited by IAA. Delay in application of IAA to red light-irradiated seeds resulted in a gradual increase in percent germination, which probably corresponded to the time-course of Pfr action. It is suggested that exogenously applied IAA probably reimposes dormancy in red light-induced seeds ofHygrophila auriculata.     

Evaluation of the leaf juice of some higher plants for their toxicity against soil borne pathogens

Out of the leaf juices of eighteen plant species screened, only Eupatorium cannabinum exhibited complete toxicity against Pythium debaryanum, Fusarium oxysporum, Rhizoctonia solani and Sclerotium rolfsii. Shade drying of the leaves had no adverse effect, while oven drying produced an adverse effect on the fungitoxicity of the leaves of E. cannabinum. The crude leaf juice of E. cannabinum successfully inhibited damping-off (Fusarium oxysporum) infection of Pisum sativum seedlings.     

Facial clefts in Saudi Arabia: an epidemiologic analysis in 179 patients

One hundred and seventy-nine consecutive cases of facial clefts that were treated at the King Khalid University Hospital, in Riyadh, Saudi Arabia, were analyzed for an epidemiologic study. Isolated cleft lip was present in 38 percent, cleft of lip and palate in 37.4 percent, and cleft of the posterior palate in only 22.4 percent. There was a male preponderance in all types. In cases of cleft lip with or without cleft palate, the more commonly affected side was the left, followed by bilateral cases. Associated malformations were present in 13.4 percent. A positive family history was found in 26.8 percent of cases. A significant number of patients (7.8 percent) were first seen at more than 10 years of age. The incidence of facial clefts at this hospital was 0.3 per 1000 live births, computed over a period of 6 years. This incidence is significantly lower than that reported from European and Far Eastern countries.     

Shift in product formation from acetate to ethanol using metabolic inhibitors inFusarium oxysporum

Summary Fusarium oxysporum 841 produces a mixture of ethanol and acetic acid from glucose, xylose or Avicel (microcrystalline cellulose) substrates. Some metabolic inhibitors viz. sodium azide, dinitrophenol and polyethylene glycol were used for shifting product formation from acetic acid to ethanol. Using these inhibitors 1.5- to 2- fold increase in ethanol production was achieved with significant repression (by 80 to 90%) of acetic acid. Almost theoretical yields of ethanol were obtained.     

Microbial growth on carbon monoxide

The utilization of carbon monoxide as energy and/or carbon source by different physiological groups of bacteria is described and compared. Utilitarian CO oxidation which is coupled to the generation of energy for growth is achieved by aerobic and anaerobic eu- and archaebacteria. They belong to the physiological groups of aerobic carboxidotrophic, facultatively anaerobic phototrophic, and anaerobic acetogenic, methanogenic or sulfate-reducing bacteria. The key enzyme in CO oxidation is CO dehydrogenase which is a molybdo iron-sulfur flavoprotein in aerobic CO-oxidizing bacteria and a nickel-containing iron-sulfur protein in anaerobic ones. In carboxidotrophic and phototrophic bacteria, the CO-born CO₂ is fixed by ribulose bisphosphate carboxylase in the reductive pentose phosphate cycle. In acetogenic, methanogenic, and probably in sulfate-reducing bacteria, CODH/acetyl-CoA synthase directly incorporates CO into acetyl-CoA.In plasmid-harbouring carboxidotrophic bacteria, CO dehydrogenase as well as enzymes involved in CO₂ fixation or hydrogen utilization are plasmid-encoded. Structural genes encoding CO dehydrogenase were cloned from carboxidotrophic, acetogenic and methanogenic bacteria. Although they are clustered in each case, they are genetically distinct.Soil is a most important biological sink for CO in nature. While the physiological microbial groups capable of CO oxidation are well known, the type and nature of the microorganisms actually representing this sink are still enigmatic. We also tried to summarize the little information available on the nutritional and physicochemical requirements determining the sink strength. Because CO is highly toxic to respiring organisms even in low concentrations, the function of microbial activities in the global CO cycle is critical.