Molecular Characterization of the Mouse Tyrosinase Gene:Pigment Cell-Specific Expression in Transgenic Mice

Tyrosinase is the key enzyme in melanin synthesis, and is expressed in the pigment epithelium of the retina, a cell layer derived from the optic cup; and in neural crest-derived melanocytes of skin, hair follicle, choroid, and iris. The tyrosinase gene has been cloned and shown to map to the well-characterized c-locus (albino locus) of the mouse. Subsequent studies demonstrated that a functional tyrosinase minigene was able to rescue the albino phenotype in transgenic mice. The transgene was expressed in a cell type-specific manner in skin and eye. During development of the mouse, the tyrosinase gene is expressed in the pigment epithelium of the retina as early as day 10.5 of gestation. In the hair follicle, tyrosinase gene expression is detected from day 16.5 onwards. This cell-type–specific expression is largely reproduced in transgenic mice. Our results suggest that sequences in the immediate vicinity of the mouse tyrosinase gene are sufficient to provide cell type-specificity and developmental regulation in melanocytes and the pigment epithelium.     

Lactobacillus gasseri in the Upper Small Intestine Impacts an ACSL3-Dependent Fatty Acid-Sensing Pathway Regulating Whole-Body Glucose Homeostasis

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A computational approach for identification of epitopes in dengue virus envelope protein: a step towards designing a universal dengue vaccine targeting endemic regions

A major problem in designing vaccine for the dengue virus has been the high antigenic variability in the envelope protein of different virus strains. In this study, a computational approach was adopted to identify a multi-epitope vaccine candidate against dengue virus that may be suitable for large populations in the dengue-endemic regions. Different bioinformatics tools were exploited that helped the identification of a conserved immunological hot-spot in the dengue envelope protein. The tools also rendered the prediction of immunogenicity and population coverage to the proposed 'in silico' vaccine candidate against dengue. A peptide region, spanning 19 amino acids, was identified in the envelope protein which found to be conserved in all four types of dengue viruses. Ten proteasomal cleavage sites were identified within the 19-mer conserved peptide sequence and a total of 8 overlapping putative cytotoxic T cell (CTL) epitopes were identified. The immunogenicity of these epitopes was evaluated in terms of their binding affinities to and dissociation half-time from respective human leukocyte antigen (HLA) molecules. The HLA allele frequencies were studied among populations in the dengue endemic regions and compared with respect to HLA restriction patterns of the overlapping epitopes. The cumulative population coverage for these epitopes as vaccine candidates was high ranging from approximately 80% to 92%. Structural analysis suggested that a 9-mer epitope fitted well into the peptide-binding groove of HLA-A*0201. In conclusion, the 19-mer epitope cluster was shown to have the potential for use as a vaccine candidate against dengue.     

Two‐step vegetation response to enhanced precipitation in Northeast Brazil during Heinrich event 1

High resolution palynological and geochemical data of sediment core GeoB 3910‐2 (located offshore Northeast Brazil) spanning the period between 19 600 and 14 500 calibrated year bp (19.6–14.5 ka) show a land‐cover change in the catchment area of local rivers in two steps related to changes in precipitation associated with Heinrich Event 1 (H1 stadial). At the end of the last glacial maximum, the landscape in semi‐arid Northeast Brazil was dominated by a very dry type of caatinga vegetation, mainly composed of grasslands with some herbs and shrubs. After 18 ka, considerably more humid conditions are suggested by changes in the vegetation and by C_org and C/N data indicative of fluvial erosion. The caatinga became wetter and along lakes and rivers, sedges and gallery forest expanded. The most humid period was recorded between 16.5 and 15 ka, when humid gallery (and floodplain) forest and even small patches of mountainous Atlantic rain forest occurred together with dry forest, the latter being considered as a rather lush type of caatinga vegetation. During this humid phase erosion decreased as less lithogenic material and more organic terrestrial material were deposited on the continental slope of northern Brazil. After 15 ka arid conditions returned. During the humid second phase of the H1 stadial, a rich variety of landscapes existed in Northeast Brazil and during the drier periods small pockets of forest could probably survive in favorable spots, which would have increased the resilience of the forest to climate change.     

Studies on Chloroplast Degradation in vivo: III. THE EFFECT OF MAGNESIUM ON ELECTRON TRANSPORT AND PHOSPHORYLATIQN IN PLASTIDS ISOLATED FROM YOUNG AND AGEING COTYLEDONS

The magnesium dependence of NADP-reduction, oxygen evolutionand concomitant ATP-formation was studied as a function of theage of the Cucurbita cotyledons from which the chloroplastswere isolated. Whereas NADP-reduction under alkaline assay conditionsalways exhibits a stimulation upon addition of Mg⁺⁺, measurementsin an acidic medium show an age-dependent reversal to inhibition.The data for oxygen evolution are more complex in nature, dueto participation of consecutive reactions. The Mg⁺⁺ concentrationfor optimal ATP formation decreases with the age of the cotyledonarymaterial. The results are discussed from the viewpoint of apossible control of essential photosynthetic functions in vivoby magnesium.     

The role of ultrasonic bat detectors in improving inventory and monitoring surveys in Vietnamese karst bat assemblages

Bats account for 30% of mammal diversity in SE Asia and are potential bioindicators of wider biodiversity impacts resulting from habitat loss and climate change.As existing sampling techniques in the region typically fail to record bats that habitually fly in open areas and at higher altitudes,current inventory efforts are less than comprehensive.Acoustic sampling with bat detectors may help to overcome these limitations for insectivorous bats,but has yet to be tested in mainland SE Asia.To do so,we sampled...     

Investigation of PAR-1-type thrombin receptors in rat glioma C6 cells with a novel monoclonal anti-PAR-1 antibody (Mab COR7-6H9)

Rat glioma C6 cells have been demonstrated to be a suitable model in the investigation of PAR-1-type thrombin receptors in brain. However, anti-PAR-1 antibodies, which should be very helpful tools in studying PAR-1 in rat cells, have not been available up until now. Therefore, we prepared a monoclonal anti-thrombin receptor antibody (Mab COR7-6H9) directed against the peptide sequence GRAVYLNKSRFPPMPPPPFISEDASG in the N-terminus below the thrombin cleavage site of the rat PAR-1-type thrombin receptor. Using this antibody, we demonstrated the presence of PAR-1 binding sites on the plasma membrane of rat glioma C6 cells both with confocal laser fluorescence and with scanning electron microscopy. In addition, Mab COR7-6H9 was shown to block PAR-1-mediated transmembranal signaling as demonstrated by measurement of free intracellular calcium and cyclic AMP. This novel anti-PAR-1 antibody is therefore likely to be a very helpful tool in studying PAR-1-type thrombin receptors in rat brain.     

Differential effects of ecotoxicological substances on lipid peroxidation of plant cell protoplasts

Abstract The determination of ethane formation in the light and dark in the presence and absence of SHAM provides a memthod for the elucidation of the mechanism of membrane destruction in plant cell protoplasts, induced by chemical treatment. Accordingly, PCP is postulated to act via radical and enzymic-mediated lipid peroxidation. In contrast, HgCl₂ appears to inhibit the enzymic pathway, and causes damage to the membranes via a radical mediated mechanism alone.