11 research outputs found

    Differences in osmotolerance in freshwater and brackish water populations of Theodoxus fluviatilis (Gastropoda: Neritidae) are associated with differential protein expression

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    The euryhaline gastropod Theodoxus fluviatilis is found in northern Germany in freshwater or in brackish water habitats in the Baltic Sea. Previous studies have revealed that individuals from both habitats are not distinguishable by morphological characters or by sequence comparison of DNA encoding 16S RNA or cytochrome C. As reported in this study, animals collected in the two habitats differ substantially in their physiological ability to adapt to different salinities. Comparison of accumulation rates of ninhydrin-positive substances (NPS) in foot muscle upon transfer of animals to higher medium salinities revealed that brackish water animals were perfectly able to mobilize NPS, while freshwater animals had only limited ability to do so. In an attempt to explore whether this difference in physiology may be caused by genetic differentiation, we compared protein expression patterns of soluble foot muscle proteins using 2D gel electrophoresis and silver staining. Of the 40 consistently detected protein spots, 27 showed similar levels in protein expression in animals collected from freshwater or brackish water habitats, respectively. In 12 spots, however, protein concentration was higher in brackish water than in freshwater animals. In four of these spots, expression levels followed increases or decreases in medium salinities. In a different set of 4 of these 12 spots, protein levels were always higher in brackish water as compared to freshwater animals, regardless of their physiological situation (14 days in artificial pond water or in medium with a salinity of 16‰). The remaining 4 of the 12 spots had complex expression patterns. Protein levels of the remaining single spot were generally higher in freshwater animals than in brackish water animals. These expression patterns may indicate that freshwater and brackish water animals of T. fluviatilis belong to different locally adapted populations with subtle genetic differentiation

    <span style="font-size:14.0pt;line-height: 115%;font-family:"Times New Roman";mso-fareast-font-family:"Times New Roman"; color:black;mso-ansi-language:EN-IN;mso-fareast-language:EN-IN;mso-bidi-language: HI" lang="EN-IN">Oxygen consumption, ammonia excretion and total ninhydrin positive substances in black clam <i>Villorita cyprinoides</i> (pelecypoda) exposed to various salinities</span>

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    80-82<span style="font-size:14.0pt;line-height: 115%;font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" color:black;mso-ansi-language:en-in;mso-fareast-language:en-in;mso-bidi-language:="" hi"="" lang="EN-IN">Changes in the rate of oxygen consumption, ammonia excretion and the tissue content of total ninhydrin positive substances in the black clam, Villorita cyprinoides, were studied during the exposure of the animal to salinities 0, 5, 10, 15 and 20 ppt. The content of total ninhydrin positive substances was found to increase with an increase in ambient salinity, maximum concentration was found at 15 ppt. Rate of oxygen consumption also showed an increase with increase in salinity. Rate of excretion of ammonia nitrogen decreased with an increase in ambient salinity. The role of ninhydrin positive substances in the osmoregulation is depicted and the existence of a degradation-synthesis balance for the regulation of osmotic effector pool is suggested.</span

    INTRACELLULAR OSMOREGULATION IN THE ESTUARINE MOLLUSC VILLORITA CYPRINOIDES VAR. COCHINENSIS (Mollusca: Bivalvia) Hanley

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    The present investigation is dedicated to understanding various mechanisms of salinity tolerance in the estuarine clam V. cyprinoides var. cochinensis. Even though V. cyprinoids var. cochinensis and V. cyprinoides are found to coexist in the same area, V. cyprinoids is reported to tolerate higher salinities than variety cochinenesis. Variations in the salinity of sea water may affect the aquatic organisms through specific gravity control and variations in osmotic pressure. The specific gravity of most soft tissues is close to that of normal seawater. Many bottom living forms, both attached and motile, have very high specific gravities eg.villorita cyprinoids. Villorita spp. Occurs abundantly in the reaches of the estuary and backwaters of Kerala. In both marine and estuarine forms, it is observed that mantle employs a lesser quantity of amino acids compared to adductor and foot. The regulation of cell volume is not carried out equally in all types of tissues. The capability of salinity tolerance is an aggregate of both the capabilities of extra cellular anisosmotic and intracellular isosmotic regulations in osmoconforming animals. The ultimate aim of water regulation is to regulate the cell volume.T here are slight changes occur in cell volume even in osmoregulators. These studies can also help in revealing the changes brought about in the cellular organelles like lysosomes, which were found to have a role in the osmoregulatory process. The osmoregulatory machinery of estuarine animals is more streamlined for a successful life in the estuarine regime

    Lysosomal stability in <i>Oreochromis mossambicus </i>(Peters) on exposure to surfactants

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    96-99The three commonly used surfactants viz. anionic sodium dodecyl sulfate (SDS), cationic cetyl tri methyl ammonium bromide (CTAB) and non-ionic triton X-100 were toxic even at sublethal levels (1 ppm for 30 days) to O. mossambicus. Lysosomal stability index (LSI) was lowest in triton-exposed animals in vitro. in vivo, CTAB was the most toxic. SDS, the anionic surfactant was the least toxic. The possible role of surfactant structure, critical micellar concentration (CMC) and metabolism in influencing the toxicity is discussed and mechanism of action via membrane lipid peroxidation is suggested

    Studies on the drift of ocean colour features using satellite-derived sea surface wind for updating potential fishing zone

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    122-128Ocean colour features like chlorophyll fronts are widely used for the prediction of Potential Fishery Zones (PFZs). These mesoscale features are dynamic since ocean surface is always in motion. They tend to drift because of surface advective movements. The present study is an attempt to understand the relationship between wind speed and drift of ocean colour features, which can be used to update the location of PFZ mesoscale features. Ocean colour images from IRS-P4 Ocean Colour Monitor (OCM) were atmospherically corrected and Ocean Chlorophyll-2 bio-optical algorithm was applied to derive the sea surface chlorophyll. QuikSCAT (NASA) scatterometer wind data was obtained from the global 25 km² gridded dataset. A mathematical relationship between wind speed and drift was derived. The relation was validated on a second set of time series images. Results show that the relation can be used for updating the location of PFZ features in the northeast Arabian Sea for up to 96 hr within an error of 12%

    Studies on the drift of ocean colour features using satellite-derived sea surface wind for updating potential fishing zone

    No full text
    Ocean colour features like chlorophyll fronts are widely used for the prediction of Potential Fishery Zones (PFZs). These mesoscale features are dynamic since ocean surface is always in motion. They tend to drift because of surface advective movements. The present study is an attempt to understand the relationship between wind speed and drift of ocean colour features, which can be used to update the location of PFZ mesoscale features. Ocean colour images from IRS-P4 Ocean Colour Monitor (OCM) were atmospherically corrected and Ocean Chlorophyll-2 bio-optical algorithm was applied to derive the sea surface chlorophyll. QuikSCAT (NASA) scatterometer wind data was obtained from the global 25 km² gridded dataset. A mathematical relationship between wind speed and drift was derived. The relation was validated on a second set of time series images. Results show that the relation can be used for updating the location of PFZ features in the northeast Arabian Sea for up to 96 hr within an error of 12%

    Assessment of surface and sub-surface waterlogged areas in irrigation command areas of Bihar state using remote sensing and GIS

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    Satellite remote sensing coupled with Geographical Information Systems (GIS) offers an excellent alternative to conventional mapping techniques in monitoring and mapping of surface and sub-surface waterlogged areas. In the present study, pre-monsoon and post-monsoon surface waterlogged areas were delineated in all the 132 irrigation command areas of the Bihar State, India using Indian Remote Sensing (IRS-1D) Linear Imaging Self Scanning Sensor (LISS-III) data acquired during the period 2002-2003. Normalized Difference Water Index (NDWI) was used primarily to delineate surface waterlogged areas. Perennial waterlogged and seasonal waterlogged areas were identified for the study area by integrating the waterlogged areas derived for both the pre- and post-monsoon seasons under GIS environment. Results show that the total surface waterlogged area in Bihar is 628 x 103 ha, which is 10.57% of command area (5939 - 103 ha) and spread over 132 command areas. Perennial surface inundation covers 2.95% of the waterlogged area in all the command areas. Maximum waterlogged area is observed in Gandak command (212 - 103 ha) followed by Eastern Kosi irrigation scheme (116 - 103 ha) and Sone modernization scheme (82 - 103 ha), respectively. Further, waterlogged areas induced by rise in groundwater level were also assessed spatially under GIS environment using the ground water level data pertaining to pre- and post-monsoon seasons of the year 2002-2003 which were spread all over the study area. The analysis of pre- and post-monsoon groundwater levels indicates that the area under non-critical category during pre-monsoon period was reduced from 4287 - 103 ha (72.72% of command) to 1391 - 103 ha (23.42%) in the post-monsoon. Area under most critical category during post-monsoon period increased from 0.083 - 103 ha of command area in pre-monsoon period to 50 - 103 ha. The study demonstrates utility of integration of remote sensing and GIS techniques for assessment of waterlogged areas particularly in regions where waterlogging conditions occur both due to excessive irrigation and accumulation of rain and floodwaters.
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