Long-chain aliphatic wax esters isolated from the sponge Chalinula saudensis (Demospongia) along the Jeddah coast of the Red Sea

A esponja Chalinula saudensis ocorre ao longo da costa de Jeddah, Arabia Saudita, mas apenas recentemente foi isolada e identificada. No presente estudo a matéria orgânica total da esponja foi extraída por solventes e o extrato foi separado por partição sucessiva através do emprego de hexano e água, clorofórmio e água e finalmente t-butanol e água. A camada contendo clorofórmio foi então separada por cromatografia em sílica. Os resultados mostraram a presença de ésteres de quatro ácidos graxos de cadeira longa (C28H56O2, C30H60O2, C32H62O2 e C36H70O2), sendo que o segundo deles foi também identificado nos corais Millepora dichotoma e Millepora platyphylla. Não se tem evidência da presença dos demais compostos em outros organismos marinhos, embora haja relatos para ésteres semelhantes de cadeia longa, mas contendo diferentes cadeias alifáticas e diferentes pesos moleculares. Os compostos isolados em C. saudensis são geralmente ceras e sua presença na esponja tem importância não só nas rotas de biosíntese, mas servem como isolantes nas variações sazonais adversas.The sponge Chalinula saudensis, which occurs along the Jeddah coast, has only recently been isolated and identified. In this study, the total crude organic matter of the sponge was extracted by solvents. The total crude extract was further separated by partitioning it with hexane and water, then with water and chloroform, and finally with water and t-butanol. The chloroform layer was subjected to separation by preparative layer chromatography on silica. One fraction contained four long-chain fatty acid esters, C28H56O2, C30H60O2, C32H62O2 and C36H70 O2. The second ester, C30H60O2, has been identified in the fire corals Millepora dichotoma and Millepora platyphylla. The others have not previously been reported from marine organisms; however similar long-chain esters with different long aliphatic chains and with different molecular weights have been identified from other marine organisms. These compounds are normally waxy and their presence in Chalinula saudensis plays a vital role in the biosynthetic pathways. They also act as insulators against seasonal variations

Formation of Zn- and Fe-sulfides near hydrothermal vents at the Eastern Lau Spreading Center: implications for sulfide bioavailability to chemoautotrophs

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Speciation and fate of trace metals in estuarine sediments under reduced and oxidized conditions, Seaplane Lagoon, Alameda Naval Air Station (USA)

We have identified important chemical reactions that control the fate of metal-contaminated estuarine sediments if they are left undisturbed (in situ) or if they are dredged. We combined information on the molecular bonding of metals in solids from X-ray absorption spectroscopy (XAS) with thermodynamic and kinetic driving forces obtained from dissolved metal concentrations to deduce the dominant reactions under reduced and oxidized conditions. We evaluated the in situ geochemistry of metals (cadmium, chromium, iron, lead, manganese and zinc) as a function of sediment depth (to 100 cm) from a 60 year record of contamination at the Alameda Naval Air Station, California. Results from XAS and thermodynamic modeling of porewaters show that cadmium and most of the zinc form stable sulfide phases, and that lead and chromium are associated with stable carbonate, phosphate, phyllosilicate, or oxide minerals. Therefore, there is minimal risk associated with the release of these trace metals from the deeper sediments contaminated prior to the Clean Water Act (1975) as long as reducing conditions are maintained. Increased concentrations of dissolved metals with depth were indicative of the formation of metal HS(- )complexes. The sediments also contain zinc, chromium, and manganese associated with detrital iron-rich phyllosilicates and/or oxides. These phases are recalcitrant at near-neutral pH and do not undergo reductive dissolution within the 60 year depositional history of sediments at this site. The fate of these metals during dredging was evaluated by comparing in situ geochemistry with that of sediments oxidized by seawater in laboratory experiments. Cadmium and zinc pose the greatest hazard from dredging because their sulfides were highly reactive in seawater. However, their dissolved concentrations under oxic conditions were limited eventually by sorption to or co-precipitation with an iron (oxy)hydroxide. About 50% of the reacted CdS and 80% of the reacted ZnS were bonded to an oxide-substrate at the end of the 90-day oxidation experiment. Lead and chromium pose a minimal hazard from dredging because they are bonded to relatively insoluble carbonate, phosphate, phyllosilicate, or oxide minerals that are stable in seawater. These results point out the specific chemical behavior of individual metals in estuarine sediments, and the need for direct confirmation of metal speciation in order to constrain predictive models that realistically assess the fate of metals in urban harbors and coastal sediments

Fatty acids composition of phospholipids in brown algae <i>Sargassum subrepandum </i> along the coast of Jeddah and bactericidal bioassay of the crude extract

1669-1676Phospholipids play an important role in the biochemical activities of cell membrane of the living organisms. Brown algae Sargassum subrepandum is normally available near the shore of Jeddah as littoral algae. Lipids were extracted from this algae using Folch Method. Phospholipids were isolated by column chromatography on silica. Methyl esters and finally the pyrrolidide derivatives of these fatty acids were prepared and analyzed by GC-MS. Eleven fatty acids were detected, the dominant being palmitic and stearic acids whereas eicosanoic acid was in the lowest quantity. The bulk of the fatty acids were saturated (85.69%). Bactericidal bioassay of the crude extract was carried out by Agar Well Diffusion Method against pathogenic organisms. It was observed that the hexane extract of the algae showed similar activity as compared to the activity of the standard drug Ampicillin

Analysis of chromosomal abnormalities in human oocytes and embryos

The chromosome constitution of human cleavage stage embryos has been extensively investi-gated using a variety of techniques, revealing high levels of aneuploidy and mosaicism. However, the final phase of preimplantation development, the blastocyst stage has received relatively little attention mostly because it is only recently that embryo culture has become sufficiently well optimised to reliabley generate blastocysts. One of the aims of this study was to examine blastocyst cytogenetics, characterising the extent and variety of aneuploidy and, where possible, determining the origin of the abnormalities detected. Both the frequency of aneuploidy and the incidence of mosaicism were significantly lower in the 52 embryos generated by 20 patients that had successfully undergone the first cellular differentiation, producing trophectoderm (TE) and inner cell mass (ICM). Valuable tools for the detailed chromosomal analysis of blastocysts, used in both research and clinical contexts, were comparative genomic hybridization (CGH) and array CGH (aCGH). However, validation of these methods, especially aCGH, was required in order to verify accuracy. A low error rate and a low misdiagnosis risk were demonstrated. The morphology of 1397 embryos at the cleavage and blastocyst stages from 229 patients was evaluated in relation to their chromosomal complement. The results obtained during this part of the project showed that, in general, there is little correlation between cleavage stage morphology and chromosome status. A weak link between morphology and aneuploidy, however, was found for embryos at the blastocyst stage. Chromosomally normal female embryos had a tendency to grow faster than male embryos at the cleavage stage and therefore tended to achieve superior morphological scores, whereas the trend was reversed at the blastocyst stage. Abnormal embryos carrying types of aneuploidy compatible with formation of a clinically recognised pregnancy had morphologies indistinguishable from those of euploid embryos. This study also aimed to utilise aCGH for the preimplantation genetic diagnosis (PGD) of imbal-ances due to structural chromosome rearrangements (e.g. translocations) in 39 carriers, a total of 139 embryos were assessed. The data obtained revealed that carriers of Robertsonian translocations are at increased risk of aneuploidy affecting additional chromosomes not involved the translocation, a phenomenon known as an interchromosomal effect (ICE). Finally, the clinical outcomes of 300 patients undergoing preimplantation genetic screening (PGS) using aCGH, for various different indications, were evaluated at both the cleavage (795 embryos) and blastocyst stages (1097 embryos). The pregnancy rate following cleavage stage biopsy was significantly lower than following blastocyst stage biopsy. The miscarriage rate was significantly reduced following PGS for patients with recurrent miscarriages. This work provided promising data supporting the clinical use of comprehensive chromosome analysis for the screening or diagnosis of preimplantation embryos and also yielded scientifically useful information concerning the frequency and nature of aneuploidy at the final stage of development before implantation.</p

Analysis of chromosomal abnormalities in human oocytes and embryos

The chromosome constitution of human cleavage stage embryos has been extensively investi-gated using a variety of techniques, revealing high levels of aneuploidy and mosaicism. However, the final phase of preimplantation development, the blastocyst stage has received relatively little attention mostly because it is only recently that embryo culture has become sufficiently well optimised to reliabley generate blastocysts. One of the aims of this study was to examine blastocyst cytogenetics, characterising the extent and variety of aneuploidy and, where possible, determining the origin of the abnormalities detected. Both the frequency of aneuploidy and the incidence of mosaicism were significantly lower in the 52 embryos generated by 20 patients that had successfully undergone the first cellular differentiation, producing trophectoderm (TE) and inner cell mass (ICM). Valuable tools for the detailed chromosomal analysis of blastocysts, used in both research and clinical contexts, were comparative genomic hybridization (CGH) and array CGH (aCGH). However, validation of these methods, especially aCGH, was required in order to verify accuracy. A low error rate and a low misdiagnosis risk were demonstrated. The morphology of 1397 embryos at the cleavage and blastocyst stages from 229 patients was evaluated in relation to their chromosomal complement. The results obtained during this part of the project showed that, in general, there is little correlation between cleavage stage morphology and chromosome status. A weak link between morphology and aneuploidy, however, was found for embryos at the blastocyst stage. Chromosomally normal female embryos had a tendency to grow faster than male embryos at the cleavage stage and therefore tended to achieve superior morphological scores, whereas the trend was reversed at the blastocyst stage. Abnormal embryos carrying types of aneuploidy compatible with formation of a clinically recognised pregnancy had morphologies indistinguishable from those of euploid embryos. This study also aimed to utilise aCGH for the preimplantation genetic diagnosis (PGD) of imbal-ances due to structural chromosome rearrangements (e.g. translocations) in 39 carriers, a total of 139 embryos were assessed. The data obtained revealed that carriers of Robertsonian translocations are at increased risk of aneuploidy affecting additional chromosomes not involved the translocation, a phenomenon known as an interchromosomal effect (ICE). Finally, the clinical outcomes of 300 patients undergoing preimplantation genetic screening (PGS) using aCGH, for various different indications, were evaluated at both the cleavage (795 embryos) and blastocyst stages (1097 embryos). The pregnancy rate following cleavage stage biopsy was significantly lower than following blastocyst stage biopsy. The miscarriage rate was significantly reduced following PGS for patients with recurrent miscarriages. This work provided promising data supporting the clinical use of comprehensive chromosome analysis for the screening or diagnosis of preimplantation embryos and also yielded scientifically useful information concerning the frequency and nature of aneuploidy at the final stage of development before implantation.This thesis is not currently available in ORA

Selenium Concentration Levels in Two Polluted Lagoons, Eastern Red Sea Coastal Waters

The importance of selenium in the marine environment is highlighted by its bilateral behavior as a nutrient and toxic element. The cathodic stripping voltammetry validated method was used to determine the selenium concentration. The concentration of total dissolved selenium (TDSe) in Al-Arbaeen and Sharm Obhur lagoons along the eastern Red Sea coastal waters was determined. The total selenium concentration in seven fish species’ muscles was determined. TDSe in the surface water of Al-Arbaeen and Sharm Obhur lagoons showed a maximum concentration of 18.56 and 8.38 nM, respectively. TDSe in the surface water of Al-Arbaeen revealed high concentrations near the wastewater discharging pipes in the lagoon. The linear regression between the TDSe and salinity reflected that the discharged water is the source of selenium with a significant negative correlation of (R2 = 0.80, p 2 = 0.78, p Herklotsichthys punctatus and Herklotsichthys revealed high concentrations of 3.99 and 2.40 µg/g, respectively, which exceeded the permissible levels of the WHO, FAO, and ASTDR