Trace element release from estuarine sediments of South Mosquito Lagoon near Kennedy Space Center

Analytical partitioning of four trace metals in estuarine sediments collected from eight sites in South Mosquito Lagoon near Kennedy Space Center, in terms of four different categories was accomplished using four different extraction techniques. The concentrations of the four trace metals, Zn, Mn, Cd, and Cu, released in interstitial water extract, 1 N ammonium acetate extract, conc. HCl extract and fusion extract of sediments as well as their concentrations in water samples collected from the same location were determined using flame atomic absorption technique. From the analytical results the percentages of total amount of each metal distributed among four different categories, interstitial water phase, acetate extractable, acid extractable and detrital crystalline material, were determined. Our results suggest that analytical partitioning of trace metals in estuarine sediments may be used to study the mechanism of incorporation of trace metals with sediments from natural waters. A correlation between the seasonal variation in the concentration of acetate extractable trace metals in the sediment and similar variation in their concentration in water was observed. A mechanism for the release of trace metals from estuarine sediments to natural water is also suggested.     

DDT residues in the River Jamuna in Delhi,India

Water, Air, &; Soil Pollution - DDT residues in water, bottom sediments and certain non-target organisms from four different sites of the river Jamuna in Delhi were monitored periodically from...     

Eumelanins and pheomelanins: characterization by electron spin resonance spectroscopy

Synthetic dopa melanin and cysteinyldopa melanin have different electron spin resonance spectra. Data are reported for mixtures of these melanins and for dopa-cysteinyldopa copolymers, which are spectroscopically similar. A simple parameterization of the spectra allows estimation of the relative amounts of (i) dopa melanin and cysteinyldopa melanin in mixtures and of (ii) dopa and cysteinyldopa incorporated into copolymers. Several natural eumelanins and pheomelanins have been characterized and shown to be copolymers.     

Physical mapping of a translocation breakpoint in neurofibromatosis

The gene for von Recklinghausen neurofibromatosis (NF1), one of the most common autosomal-dominant disorders of humans, was recently mapped to chromosome 17 by linkage analysis. The identification of two NF1 patients with balanced translocations that involved chromosome 17q11.2 suggests that the disease can arise by gross rearrangement of the NF1 locus, and that the NF1 gene might be identified by cloning the region around these translocation breakpoints. To further define the region of these translocations, a series of chromosome 17 Not I-linking clones has been mapped to proximal 17q and studied by pulsed-field gel electrophoresis. One clone, 17L1 (D17S133), clearly identifies the breakpoint in an NF1 patient with a t(1;17) translocation. A 2.3-megabase pulsed-field map of this region was constructed and indicates that the NF1 breakpoint is only 10 to 240 kilobases away from 17L1. This finding prepares the way for the cloning of NF1.     

Flexible retinotopy: motion-dependent position coding in the visual cortex

Although the visual cortex is organized retinotopically, it is not clear whether the cortical representation of position necessarily reflects perceived position. Using functional magnetic resonance imaging (fMRI), we show that the retinotopic representation of a stationary object in the cortex was systematically shifted when visual motion was present in the scene. Whereas the object could appear shifted in the direction of the visual motion, the representation of the object in the visual cortex was always shifted in the opposite direction. The results show that the representation of position in the primary visual cortex, as revealed by fMRI, can be dissociated from perceived location.     

Capillary wrinkling of floating thin polymer films

A freely floating polymer film, tens of nanometers in thickness, wrinkles under the capillary force exerted by a drop of water placed on its surface. The wrinkling pattern is characterized by the number and length of the wrinkles. The dependence of the number of wrinkles on the elastic properties of the film and on the capillary force exerted by the drop confirms recent theoretical predictions on the selection of a pattern with a well-defined length scale in the wrinkling instability. We combined scaling relations that were developed for the length of the wrinkles with those for the number of wrinkles to construct a metrology for measuring the elasticity and thickness of ultrathin films that relies on no more than a dish of fluid and a low-magnification microscope. We validated this method on polymer films modified by plasticizer. The relaxation of the wrinkles affords a simple method to study the viscoelastic response of ultrathin films.     

Potentiation of warfarin toxicity to roof rats (Rattus rattus) by L-histidine and by vitamin K adsorbers

The efficacy of warfarin alone or with various additives was tested against roof rats (Rattus rattus). Warfarin alone at 50 mg kg^?1 of bait killed 37% of the roof rats where-as the additives, L -histidine (40 mg kg^?1 of bait), activated-clay, charcoal and carbon (10 g kg^?1 of bait), tested individually, produced no mortality. However, when warfarin wascombined with each of these additives in turn, only the L -histidine combination resulted in 100% mortality while the other combinations killed 88, 75 and 63% of the test rats respectively. Further trials of paired comparison tests were carried out in order to evaluate the efficacy of the warfarin/L -histidine combination under different environmental conditions. All the rats succumbed to this combination in both cage and rattery conditions when there was no alternative food. Mortality decreased to 60% in cage and 70% in rattery when alternative food was provided alongside the poison bait. Rats tended to die more quickly with the L -histidine combination than with warfarin alone. Field trials also confirmed that this combination was effective in reducing roof rat infestations as shown by the yield of corpses, the post-poison bait intake and post-operational surveillance.     

Validating the assessment of bull sperm morphology by veterinary practitioners

The objective of this study was to validate the assessment of bull sperm morphology done by veterinary practitioners. Out of 1606 bulls, 1400 (87.2%) and 1344 (83.7%) were designated by practitioners and an experienced andrologist, respectively, as having > 70% morphologically normal sperm. In 92% of the evaluations, there was agreement between the designations chosen.     

Cloning and analysis of the gene for a major surface antigen of Mycoplasma gallisepticum

Myplasma gallisepticum infects a wide variety of gallineaceous birds including chickens, turkeys, and pheasants. Infection occurs both horizontally and vertically. Thus, control of the spread of M. gallisepticum to noninfected flocks is difficult. Continual monitoring is necessary to identify infected flocks even under the most stringent infectious control practices. Monitoring, however, is usually performed by measuring hemagglutination activity (HA) in serum, an insensitive and variable test. Variability in the HA test arises differences in agglutination antigen, changes in antigenic profiles of the M. gallisepticum strain, and variability in reading the agglutination reaction. Enzyme-linked immunosorbent assays (ELISAs) are the preferred method of testing because of the ease in obtaining sera and the sensitivity and reproducibility of the assays, but the ELISA suffers from a lack of standardization in the test antigen. The ELISA test will be more easily accepted once the test antigen has been standardized. To this end, we have identified, cloned, and characterized the gene for an antigen that has potential as a species-specific antigen for M. gallisepticum The gene codes for a 75-kD protein, P75, that is recognized during natural infections. Recombinant P75 is not recognized in immunoblots by convalescent sera produced in chickens infected with Mycoplasma synoviae, Mycoplasma gallinarum, and Mycoplasma gallinaceum or in turkeys infected with Mycoplasma meleagridis.