Carbohydrates of the brown seaweed Dictyota dichotoma

The fucose-containing polysaccharides of the brown alga Dictyota dichotoma were extracted with either trichloroacetic acid or HCl to give both water-soluble and water-insoluble materials. The latter had a high proportion (16 to 11%) of protein, and although all the sugars found in the water-soluble extracts were present, the major sugar in these water-insoluble polysaccharides was glucose. The water-soluble material extracted with HCl was a protein-free sulphated heteropolysaccharide. Complete removal of a glucan from the water-soluble extract was achieved by fractional precipitation with ethanol. The recovered glucan-free sulphated polysaccharide, which was rich in glucuronic acid, galactose, fucose and sulphate, showed high anticoagulating activity.     

Utilization of kerosene by a hydrocarbon-assimilating strain of Fusarium oxisporum

Fusarium oxysporum IFO 6384 was grown in three different media, one containing glucose and two containing kerosene as carbon source. One of the kerosene media contained also Tween 60. The harvested dry mats were weighed at various stages of growth. Substitution of glucose with kerosene led to a sharp drop in the production of fungal mycelia. Analysis of the mat samples representing maximum yields indicated that the mycelia grown in the kerosene media were richer in free amino acid and poorer in protein as well as in polymeric and low-molecular weight carbohydrates than those grown in the glucose medium. Treatment of the culture filtrates with three volumes of acetone led to the separation of two fractions. In the first, acetone soluble fraction the free sugars and amino acids were determined, whereas the second, acetone precipitable one, was examined for its proteolytic activity. The gelatinase activity of the acetone precipitable material (APM) obtained from the kerosene media was lower than that from the glucose medium. The former activity, in contrast to the latter reached its maximum and minimum values at pHs 4 and 9, respectively.     

Studies on the mechanism of haloacetonitrile-induced gastrointestinal toxicity: interaction of dibromoacetonitrile with glutathione and glutathione-S-transferase in rats

The haloacetonitrile, dibromoacetonitrile (DBAN), is a direct-acting genotoxic agent that has been detected in drinking water. In a time course study, male Sprague-Dawley rats were treated with DBAN (75 mg/kg PO), and killed at 0.5, 1, 2, and 4 hr after treatment. In a dose response study, animals were treated orally with various doses of DBAN (25, 50, 75, and 100 mg/kg) and killed at one-half hour after treatment. Control animals received 1 ml/kg PO of the vehicle dimethyl sulfoxide (DMSO). In both experiments blood and organs were collected and stored at -80 degrees C until the time of analysis. At 0.5 hr after treatment, a single oral dose of DBAN caused a significant decrease of glutathione (GSH) concentrations in liver (54% of control) and stomach (6% of control). Hepatic GSH depletion was maximal at 0.5 hr and rebound to the control levels by 4 hr. In contrast, gastric GSH concentrations remained low at all time points. DBAN caused an insignificant change in both kidney and blood GSH levels. DBAN significantly inhibited glutathione-S-transferase (GST) activity in liver and stomach. Hepatic GST inhibition was maximal (34% of control) at 2 hr and minimal (80% of control) at 4 hr. Meanwhile, in the stomach GST activity was inhibited at 1 hr (60% of control) and remained low at all times after treatment. Both GSH depletion and GST inhibition were dose-dependent. This study indicates that GSH and GST play an important role in the metabolism and detoxification of DBAN in rats. The prolonged depletion of GSH and inhibition of GST in the gastrointestinal (GI) tissues suggest that the GI tract is a major target for DBAN toxicity.     

Sulphated heteropolysaccharides from Padina pavonia

Extraction with hydrochloric acid (pH 2.5) of the brown alga Padina pavonia afforded water-soluble and water-insoluble polysaccharides comprising D-glucuronic acid, L-fucose, D-xylose, D-mannose, D-glucose and D- galactose residues. The water-soluble polysaccharide was fractionated by using ethanol, and cetylpyridinium chloride and by chromatography on DEAE-cellulose. A neutral laminaran-like glucan, a sulphated heteropolysaccharide composed of the aforementioned sugars and a protein moiety were obtained. The isolated heteropolysaccharide showed high anticoagulation activity.     

Diallel analysis for some quantitative characters in Petunia hybrida Hort

Summary Flowering time, plant height and flower size in Petunia hybrida Hort. (multiflora type) have been genetically analysed by means of a 5 × 5 diallel cross. The results indicated that: (1) the three characters are controlled by additive-dominance polygenic systems. The contribution of the additive gene actions to the genetic variance of flowering time was relatively higher than that of dominance. The reverse situation was found for plant height and flower size. (2) Dominance is ambi-directional for the three characters. Ratios of average dominance were in the range of partial for flowering-time, complete for plant height and overdominance for flower size. (3) Number of genes (or gene groups) controlling the characters are about 3, 3 and 5 for flowering time, plant height and flower size: respectively, (4) Heritability estimates are 0.84, 0.88 and 0.89 in the broad-sense and 0.40, 0.49 and 0.37 in the narrow-sense, for flowering time, plant height and flower size; respectively. (5) Heterosis as percent increase of the mean F₁-hybrid above the higher parent, or decrease below the lower parent, was observed for flowering time (+ 9.7% to +13.3%), for plant height (–13.6% to –20.3%) and for flower size (+2.5% to +16.0%).     

Bacteriostatic and Bactericidal Activities of Camel Lactoferrins Against Salmonella enterica Serovar Typhi

Probiotics and Antimicrobial Proteins - Lactoferrin is an iron-binding glycoprotein present in various secretions (e.g., milk, tears, saliva, pancreatic juice), which performs multiple functions,...     

Competitive interactions between entomopathogenic nematodes and parasitoid venom

Entomopathogenic nematodes and parasitoid larvae of some wasps play important roles in the natural control of the pest insects. However, it has not been excluded that competition between nematodes and wasps may in some cases reduce their efficacy in the pest control. Using caterpillars of Spodoptera littoralis, we examined interactions between the nematode Steinernema carpocapsae and the venom of the parasitoid Habrobracon hebetor. The survival of S. littoralis caterpillars was reduced in a dose-dependent manner when 5 to 500 nematodes or 0.005–0.1 venom units were applied to single caterpillars. High doses of either nematodes or the venom caused death within 1–3 days in all treated hosts. The low doses of nematodes killed caterpillars within a week, in some cases when they attempted to pupate. Caterpillars receiving low venom doses were characterized by extended survival time terminated with death due to starvation. Combined treatment of nematodes and the venom were mutually synergistic and elicited severe lethal effects. The nematodes were fully resistant to the venom and can feed and grow on the symbiotic bacteria in vitro. The venom impairs food processing and causes death of caterpillars due to starvation. Disruption of the hormonal regulation of metamorphosis by ecdysteroids and juvenile hormone could be responsible for defective moults block at different stages of the moulting process, regionally restricted moulting, moults to “intermediates” combining regions of newly secreted larval and pupal cuticles.