Assessing water quality and classifying trophic status for scientifically based managing the water resources of the Lake Timsah,the lake with salinity stratification along the Suez Canal

Lake Timsah is considered as the biggest water body at Ismailia City with a surface area of 14?km². It is a saline shallow water basin lies approximately mid-way between the south city of Suez and the north city of Port Said at 30^o35′46.55“N and 32^o19′30.54″E. Because it receives water with high and low salinities, salinity stratification is producing in the Lake Timsah, with values of 14–40‰ for the surface water and over 40‰ for the bottom water. The temperature of the lake water decreased to below 19 °C in the winter and rose to above 29?°C in the summer; the concentration of dissolved oxygen ranged between 6.5 and 12.2?l^?1 and the pH fluctuated between 7.9 in its lower value and 8.2 in its higher value. Water transparency was very low as indicated by Secchi disc readings recorded during this study and varied between 0.3 and 2.7?m. The main chemical nutrient (phosphorus) reached its highest levels of 96?µg?l^?1 in winter and their lowest values of 24?µg?l^?1 during summer. This nutrient concentration is high especially by comparing with those of unpolluted marine waters, but is typical of the more eutrophic coastal waters worldwide. The composition and abundance of phytoplankton with dominancy of diatoms and increased population density (20,986 cell l^?1) reflect the eutrophic condition of the lake. The intensive growth of phytoplankton was enriched by high concentration of chlorophyll a with annual values ranged between 6.5 and 56?µg?l^?1. The objective of the present work was quantitative assessment of the quality of the water of the Lake Timsah using different approaches. During the present study, three different approaches were applied for the quantitative assessment of Lake Timsah water quality: the trophic state index (TST); trophic level index (TLI) and water quality index (WQI). Application of the trophic state and trophic level indices (TSI & TLI) revealed that the Lake Timsah has trophic indices of 60 and 5.2 for TSI and TLI, respectively. Both indices reflected the eutrophic condition of the lake waters and confirmed that the eutrophication is a major threat in the Lake Timsah. On the other hand, the WQI calculated for the Lake Timsah during the present study with an average of 49 demonstrated that the water of the Lake Timsah is bad and unsuitable for main and/or several uses. Moreover, WQI allows accounting for several water resource uses and can serve a more robust than TSI and/or TLI and can be used effectively as a comprehensive tool for water quality quantification. In conclusion, the three subjective indices used for the assessment process for the lake water are more suitable and effective for needs of the sustainable water resources protection and management of the Lake Timsah.     

Improved chromosome doubling of parthenogenetic haploid plants of cucumber (<Emphasis Type="Italic">Cucumis sativus</Emphasis> L.) using colchicine,trifluralin, and oryzalin

An effective chromosome doubling protocol was established in essential garden crop of cucumber (Cucumis sativus L.) Cv. Hi Power. The different concentrations of colchicine (0, 250, 500, 750, and 1500 mg/L), oryzalin (0, 5, 15, 25, 50, 75, and 150 mg/L) and trifluralin (0, 5, 15, 25, 50, 75, and 150 mg/L) were applied on parthenogenesis-induced haploid nodal and shoot tip explants of cucumber for 18 and 38 h in three independent factorial experiments. Increasing concentrations of applied antimitotic agents led to the significant reduction in the survival rate of both shoot tip and nodal explants, especially in longer exposure duration. Three ploidy levels including haploid, mixoploid, and doubled haploid were regenerated form both explant types treated with colchicine, oryzalin, and trifluralin. Flow cytometry analysis proved successful chromosome doubling of haploid plants. Based on the results obtained, the highest number of regenerated doubled haploid plants (92.31%) and fruit set (86.21%) were related to immersion of nodal explants in 50 mg/L oryzalin for 18 h. The highest doubled haploid regeneration for colchicine and trifluralin antimitotic agents were 58.33 and 83.33%, respectively. The leaf size of doubled haploid plants was larger than their correspond haploids. The optimized chromosome doubling protocol would be applicable for doubled haploid production in garden crops of Cucurbitaceae family, which is recalcitrant to the spontaneous doubling, and also for in vitro polyploidy induction studies.     

Characterization of chitinases and β-1,3-glucanases in grapefruit flavedo during fruit development

Chitinase (EC 3.2.1.14) and β-1,3-glucanase (EC 3.2.1.39) activities in the flavedo of grapefruit ( Citrus paradisi cv. Marsh) were determined at 17 times during the course of fruit development. Chitinase activity is initially high in flavedo, but drops rapidly and is low, although fairly constant throughout the remainder of fruit development. In contrast to chitinase, β-1,3-glucanase activity is lowest in young fruit and increases during development. Western blots of crude flavedo extracts following SDS-PAGE were probed with antibodies raised against purified citrus chitinase and β-1,3-glucanase. Results of immunostaining revealed that changes in the activities of chitinase and β-1,3-glucanase were reflected in the amount of chitinase and glucanase protein present in the extracts. Only a single chitinase band was detected on western blots of crude flavedo extracts, whereas one glucanase band was present in young fruit and a second one appeared later in older fruit. Partial purification of flavedo chitinases and glucanases was performed using extracts prepared from immature and mature fruit for the two enzymes, respectively. Acidic and basic forms of both enzymes were present in the extracts; acidic and basic forms of chitinase were present in nearly equal amounts whereas basic glucanases predominated (91% of total activity). Acidic and basic chitinases differed in substrate specificity as well as products of degradation indicating the heterogeneous nature of the enzymes. Both acidic and basic glucanases required the presence of β-1,3 linkages for activity, were active against both soluble and insoluble β-1,3 glucans and generated similar products.