Seasonal effect on biomarkers of exposure to petroleum hydrocarbons in fish from Kuwait's marine area.

The aquatic biota of the Arabian Gulf deals with exposure to chronic oil pollution, several constituents of which cause induction of Cytochrome P450 1A that serves as a biomarker of AhR ligand exposure. In this study, fluorescent aromatic compounds (FACs) in bile and 7-ethoxyresorufin-o-deethylase (EROD) catalytic activity were determined as a measure of exposure biomarkers in two fish species, yellow fin seabream (Acanthopagrus latus) and tonguesole (Cynoglossus arel) captured from Kuwait Bay and outside the Bay area. FACs in fish bile determined by using fixed-wavelength fluorescence (FF) showed high fluorescence ratios between FF290/335 and FF380/430 indicating predominant exposure to low molecular weight, naphthalene-rich petroleum products (375±91.0 pg ml(-1)). Exposures to benzo(a)pyrene-type high-molecular weight polycyclic aromatic hydrocarbons (PAHs) originating from burnt fuel were also present in appreciable concentration in the bile. The ratio of petrogenic to pyrogenic hydrocarbon was twofold higher in winter compared to summer months in both species. Seasonal effect on EROD was significant in tonguesole in Auha site (P<0.05); whereas seabream resisted seasonal change. Tonguesole is considered to be a suitable bioindicator of oil pollution in Kuwait Bay area.

Metallothionein, oxidative stress and trace metals in gills and liver of demersal and pelagic fish species from Kuwaits' marine area.

Two fish species yellowfin seabream (Acanthopagrus latus) and tonguesole (Cynoglossus arel) were collected from two locations in Kuwait's territorial waters in non-reproductive periods and used as bio-indicator organism for the assessment of metals in the marine environment. Species variation in fish was observed; seabream contained high metal content and metallothionein in liver and gill tissues compared to tonguesole, especially from Kuwait Bay area. Oxidative injury was registered in the gills of both species, but in tonguesole liver was also involved. Consequently, antioxidant enzyme catalase was elevated in tonguesole enabling bottom dwelling fish to combat oxidative assault. The study provided information about the current status of metals in marine sediment and levels of metals accumulated in representative species along with oxidative damage in exposed tissues and the range of biomarker protein metallothionein and enzymes of antioxidant defence mechanism enhancing our understanding about the biological response to the existing marine environment in Kuwait.

Seasonal effect on heat shock proteins in fish from Kuwait bay.

Heat shock proteins (HSP70) play a significant role in adaptation to temperature and have been proposed as an indicator of cellular stress. Since the water temperature in Kuwait's marine area varies from 13 to 35 degrees C from winter to summer, HSP70 could be a valuable tool in aquaculture in Kuwait. HSP70 levels were quantified by Western blotting in liver, muscle and gill tissues of two varieties of native fish species captured during the winter and summer months from both inside and outside the highly stressed Kuwait Bay area. The HSP70 levels did not differ statistically between fish captured from the two sampling areas. The most common response in both species was higher median levels of HSP70 in winter months. This inverse relation between HSP70 levels in the fish and the water temperature may be due to either genetic adaptation in the fish to the hot climatic conditions of the region or other stressors, such as changes in pollutant levels in the surrounding water.

A novel mutation within the rhodopsin gene (Thr-94-Ile) causing autosomal dominant congenital stationary night blindness.

More than 100 mutations within the rhodopsin gene have been found to be responsible for some forms of retinitis pigmentosa, a progressive retinal degeneration characterized by night blindness and subsequent disturbance of day vision that may eventually result in total blindness. Congenital stationary night blindness (CSNB) is an uncommon inherited retinal dysfunction in which patients complain of night vision difficulties of a nonprogressive nature only and in which generally there is no involvement of day vision. We report the results of molecular genetic analysis of an Irish family segregating an autosomal dominant form of CSNB in which a previously unreported threonine-to-isoleucine substitution at codon 94 in the rhodopsin gene was found to segregate with the disease. Computer modeling suggests that constitutive activation of transducin by the altered rhodopsin protein may be a mechanism for disease causation in this family. Only two mutations within the rhodopsin gene have been previously reported in patients with congenital stationary night blindness, constitutive activation also having been proposed as a possible disease mechanism.

Strategems in vitro for gene therapies directed to dominant mutations.

A major difficulty associated with the design of gene therapies for autosomal dominant diseases is the immense intragenic heterogeneity often encountered in such conditions. In order to overcome such difficulties we have designed, and evaluated in vitro, three strategies which avoid a requirement to target individual mutations for genetic suppression. In the first, normal and mutant alleles are suppressed by targeting sequences in transcribed but untranslated regions of transcript (UTRs), enabling introduction of a replacement gene with the correct coding sequencing but altered UTRs to prevent suppression. A second approach involves suppression in coding sequence and concurrent introduction of a replacement gene by exploiting the degeneracy of the genetic code. A third strategy utilises intragenic polymorphism to suppress the disease allele specifically, the advantage being that a proportion of patients with different disease mutations have the same polymorphism. These approaches provide a wider choice of target sequence than those directed to single disease mutations and are appropriate for many mutations within a given gene. General methods for suppression may be directed towards the primary defect or a secondary effect associated with the disease process, such as apoptosis. Three general methods targeting the primary defect which circumvent problems of allelic genetic heterogeneity are explored in vitro using hammerhead ribozymes designed to target transcripts from the rhodopsin, peripherin and collagen 1A1 and 1A2 genes, extensive genetic heterogeneity being a feature of associated disease pathologies.