Bioactive Secondary Metabolites from the Red Sea Marine Verongid Sponge Suberea Species

In a continuation of our efforts to identify bioactive compounds from Red Sea Verongid sponges, the organic extract of the sponge Suberea species afforded seven compounds including two new dibrominated alkaloids, subereamollines C and D (1 and 2), together with the known compounds aerothionin (3), homoaerothionin (4), aeroplysinin-1 (5), aeroplysinin-2 (6) and a revised subereaphenol C (7) as ethyl 2-(2,4-dibromo-3,6-dihydroxyphenyl)acetate. The structures of the isolated compounds were assigned by different spectral data including optical rotations, 1D (¹H and ¹³C) and 2D (COSY, multiplicity-edited HSQC, and HMBC) NMR and high-resolution mass spectroscopy. Aerothionin (3) and subereaphenol C (7) displayed potent cytotoxic activity against HeLa cell line with IC₅₀ values of 29 and 13.3 µM, respectively. In addition, aeroplysinin-2 (6) showed potent antimigratory activity against the human breast cancer cell line MDA-MB-231 with IC₅₀ of 18 µM. Subereamollines C and D are new congeners of the previously reported compounds subereamollines A and B with methyl ester functionalities on the side chain. These findings provide further insight into the biosynthetic capabilities of members of the genus Suberea and the chemical diversity as well as the biological activity of these compounds.     

Haemodynamic alterations induced by toxic level of sodium taurocholate

Haemodynamic effects of sodium taurocholate (S.T.) were studied on isolated guinea pig's auricles, rabbit's heart, rabbit's aortic strip, guinea pig's tracheal chain as well as the blood pressure and ECG pattern changes in pentobarbital anaesthetized dogs. S.T. induced significant negative inotropic and chronotropic effects on the isolated auricles of guinea pig's especially in higher concentrations. Using isolated rabbit's heart, the negative inotropic and chronotropic effects induced by S.T. were found to be depending on the concentration. Cardio-inhibitory actions of the salt are not due to either cholinergic beta 1-adrenergic blocking effect or nicotine like activity. S.T. in all tested concentrations had no effect on the contractile response of isolated rabbit's aortic strip or guinea pig's tracheal chain and did not prevent the contractile response induced by noradrenaline and histamine. In anaesthetized dogs, i.v. injections of the salt in a dose of 30 mg/kg b. wt. produced a significant decrease in systolic and diastolic pressure, but lower doses induced no significant changes. A dose of 30 mg/kg b. wt. of the salt potentiates the decrease in systolic and diastolic pressure when coadministered with the neuromuscular blocking agent, atracurium besylate. Atropine, propranolol and phentolamine did not alter the hypotensive effect of S.T. (neither cholinergic nor beta 1-adrenergic blocking effect). The electrocardiographic pattern induced by S.T. (20-30 mg/kg b. wt.) in dogs were mainly characterized by decrease in heart rate and prolongation of P-T interval.     

“Take only photographs and leave only footprints”?: An experimental study of the impacts of underwater photographers on coral reef dive sites

Impacts caused by recreational scuba diving on coral reefs vary widely among different dive locations and individual divers. Linear modelling was used to explore a range of individual and situational risk factors associated with divers who damaged corals in the Great Barrier Reef Marine Park. Recreational divers were followed for 10–15 min, and all contacts with, and damage to corals were recorded. Information on the dive site, diving experience, gender, and use of an underwater camera were recorded. Thirty-two out of 214 divers (15%) damaged or broke corals, mostly by fin kicks (95%). Impacts were most likely to be caused by male divers, in the first 10 min of the dive, at sites with a large abundance of branching corals. Specialist underwater photographers caused more damage on average (1.6 breaks per 10 min) than divers without cameras (0.3 breaks per 10 min). To explore the effects of gender and use of a camera further, we issued single-use underwater cameras to 31 randomly chosen divers and compared their behaviour to a control group. Use of a camera had no influence on the rate or amount of damage caused by these naïve photographers, but male divers were more likely to break corals and caused significantly more damage, on average, (1.4 breaks per 15 min) than female divers (0.3 breaks per 15 min). Variability in the amount of damage caused by divers in our sample reflected the very different underwater behaviours exhibited by specialist and non-specialist photographers, and male and female divers. Greater understanding of the causes of harmful behaviours by these groups will allow better targeting of on-site interpretative and cautionary information and may prove to be a more palatable management strategy than regulation of site use.     

The variation of phosphorous content,grain yield,and rhizosphere microbial biomass among durum wheat cultivars under salinity stress

ABSTRACT

The effectiveness of plant–soil synergies is largely modulated by interaction between cultivar and rhizosphere microbiome. We evaluated the agronomic performance of six durum wheat cultivars, in two semi-arid locations in Tunisia that differed in their irrigation water salinity: S1 (6 dS m^?1) and S2 (12 dS m^?1). The two-consecutive-year field experiments assessed the effects of the microbial biomass carbon (MBC), leaf phosphorus (LP) and rhizosphere phosphorus (P) on the grain yield (GY) and yield components at tillering and flowering stages. Overall, in saline conditions, cultivars differed in above- and below-ground traits, particularly, with tolerant cultivars presenting relatively greater MBC, P and LP. Furthermore, in S2, GY positively correlated with MBC (r = 0.69), LP (r = 0.80) and P (r = 0.79). Additionally, in S2, MBC positively correlated with P (r = 0.87) and LP (r = 0.85) at flowering. This result was further confirmed by multiple linear regression (step-wise) analysis, which revealed that MBC and LP were the determinant components of GY variability under S2. The present study demonstrates that LP and soil P are mandatory for improving the management of durum wheat. Salinity tolerance was largely affected by the cultivars’ rhizosphere MBC.     

<Emphasis Type="Italic"> Gluconacetobacter diazotrophicus</Emphasis>: a natural endophytic diazotroph of Nile Delta sugarcane capable of establishing an endophytic association with wheat

Gluconacetobacter- like diazotrophs were encountered as dense populations inside the root and stem tissues of sugarcane cultivated in ancient agricultural fields of the Nile Delta. Counts of >10⁵ cells g^-1 were recorded in root and stem samples. The leaves contained a smaller population (<10³ g^-1). The typical dark-orange colonies which developed on LGIP agar plates were purified. Identification was performed with the API microtube systems: API 20E for Enterobacteriaceae and API 20NE for non-Enterobacteriaceae. API profiles of the local isolates were closely related to those of the type culture Gluconacetobacter diazotrophicus (ATTC 49037). The isolates successfully reduced C₂H₂ and produced appreciable amounts of ethylene in the presence of cane juice. This suggested that the local isolates are closely related to the type strain G. diazotrophicus. Wheat seedlings were inoculated with a number of isolates under gnotobiotic conditions. Both optical and scanning electron microscopy showed that endophytic Gluconacetobacter spp. were present in all the samples tested. They were observed in apparently intact and enlarged epidermal root cells, and also in stem tissues, indicating that the bacterium was able to migrate upward into the shoot tissues. Although Gluconacetobacter inoculation did not stimulate the growth of the cereal plant, the results obtained are particularly interesting because this bacterial species was capable of colonizing the internal tissues of wheat, not considered a natural host until now.     

Distribution of microbial biomass across the rhizosphere of barley (Hordeum vulgare L.) in soils

Summary The microbial activity at the soil-root interface (rhizosphere) of barley was examined using a rhizobox system. In this system, the soil was placed in several compartments separated from each other by a 500-mesh nylon cloth. Plants were grown in the central compartment and after a 2-month growing period the roots were still confined to this compartment. The soil from each compartment was then analyzed for ATP, NO₃ ^/–, total N, total C and CO₂ production. The increase in ATP concentration was found in a range of 4 mm around the roots. The ATP content and CO₂ production across the rhizosphere were correlated in all the soils used, but changes in NO₃ ^– were not correlated with ATP changes. The range of NO₃ ^– change was wider than that of the ATP change, indicating that NO₃ ^– production is not influenced by the biological activity in the rhizosphere.     

Fate of postharvest-applied dichlorvos in stored and processed dates

The fate of dichlorvos (DDVP) on dates after storage and processing of postharvest-treated fruits has been investigated. Residues were determined using GC-ECD after extraction of the fruits. A postharvest application was made to fruits at different stages of maturity: khalal fruits (mature full colored stage), rutab fruits (soft brown stage), and the mature tamer fruits (hard raisin-like stage). The fate of the residues was followed during the storage at refrigerated, room, and summer average temperatures (3, 22, and 43 degrees C). The amount of residues absorbed varied with the level of maturity. The rate of the loss of the residues was found to follow first-order kinetics. First-order rate constants were calculated for the different levels of maturity. The rate of the loss of DDVP increased as the temperature of storage increased. Also, it decreased with increasing maturation of the dates, which was characterized by a decrease in moisture content as well as water activity and an increase in sugar content. The period of storage study was limited by the time of maturation to the next stage. Most common home-cooking methods, including dehydration, jam-making, and syrup-making, resulted in significant decreases in residue levels. Only 0-13% of initial DDVP residues was detected in final products.     

Pharmacokinetic profile of cefotaxime in goats

Cefotaxime was administered to goats intravenously, intramuscularly and subcutaneously to determine blood and urine concentration, kinetic behaviour and bioavailability. Following a single intravenous injection, the blood concentration-time curve indicated a two compartment open model, with an elimination half-life value (t1/2 beta) of 22.38 +/- 0.41 minutes. Both intramuscular and subcutaneous routes showed slower values, that is, 38.64 and 69.58 minutes. The apparent volume of distribution of cefotaxime in goats was less than 1 litre kg-1 and suggested a lower distribution in tissues than in blood. After intramuscular and subcutaneous injections peak plasma cefotaxime concentrations were 77.8 +/- 1.7 and 44.0 +/- 0.8 micrograms ml-1 at 29.6 and 40.4 minutes, respectively. The average bioavailability of cefotaxime given by intramuscular and subcutaneous injection was 1.08 and 1.25 times the intravenous availability, respectively. The cefotaxime concentration remained in urine 24 hours longer after subcutaneous injection than after intramuscular administration.     

Improving Lettuce Yield and Quality of an Agricultural Soil Using a Combination of Arbuscular Mycorrhizal Fungus and Phosphate-Green Wastes Compost

The use of biofertilizers on agricultural soils could act positively to improve soil fertility and crop productivity. This work was performed to assess the potential beneficial impacts of local produced phospho-compost and/or an exogenous arbuscular mycorrhizal fungus (AMF) (Rhizoglomus irregulare DAOM 197198) on lettuce agro-physiological and soil characteristics under filed conditions. Four treatments were applied: control treatment without any biofertilizer, compost, AMF, and compost?+?AMF treatments. Obtained results showed that shoot nitrogen (N) and phosphorus (P) were significantly improved in lettuce plants treated with compost supplementation and/or AMF inoculation compared to the control with a maximum increment for P in plants treated with compost (106%). As for growth traits, lettuce plants treated with compost?+?AMF recorded the highest values in terms of shoot and root dry weights and yield by 121, 54 and 127%, respectively, compared to the control plants. Considering physiological and biochemical traits, stomatal conductance, and chlorophyll fluorescence as well leaf area index and total soluble sugar and protein concentration were significantly improved in plants treated with compost and/or AMF compared to the control. In addition, soil properties, especially the soil total organic carbon, N, P, and glomalin-related soil protein content were significantly enhanced after two months of field experiment in treated soils with the applied biofertilizers alone or in combination compared to the control. Based on the main obtained results, applied biofertilizers were able to increase lettuce productivity and soil fertility under field conditions, especially the compost?+?AMF treatment, which demonstrated an effectiveness promotion of lettuce productivity and soil fertility.

     

Immunohistochemical and histopathological findings of ovine pulmonary adenocarcinoma (Jaagsiekte) in Egyptian sheep

Ovine pulmonary adenocarcinoma (OPA) is a naturally occurring retrovirus-induced transmissible lung cancer in sheep. Lungs and associated (bronchial and mediastinal) lymph nodes of seven sheep with OPA were examined. Lungs had few multifocal consolidated slightly elevated gray to white masses ranging from 0.5 to 3 cm in diameter. Histopathologically, these masses appeared as well-differentiated acinar adenocarcinoma with little evidence of anaplasia. The acini composed of well-differentiated cuboidal to low columnar epithelium with clear or vacuolated cytoplasm and low mitotic index. No metastases were observed in the bronchial and mediastinal lymph nodes of any animal. The presence of Jaagsiekte sheep retrovirus (JSRV) was demonstrated in the lungs by immunohistochemistry. JSRV protein was detected in all tumor epithelial cells, histologically normal alveolar type II cells, and few bronchiolar epithelial cells, alveolar macrophages, lymphocytes, and plasma cells. This study is the first to confirm the presence of natural OPA in Egypt.