Larval mouthpart deformities in Procladius paludicola Skuse (Diptera: Chironomidae) from the Murray and Darling Rivers,Australia

A high incidence of ligula (mouthpart) deformities is reported for the larvae of Procladius paludicola Skuse (Diptera: Chironomidae) collected from sites on the Murray and Darling Rivers, Australia. This is the first report of deformities in Australian freshwater insects, and is discussed in relation to known toxic pollutants within the catchment.     

Distribution of nutrients,trace elements,PAHs and radionuclides in sediment cores from Lake Varese (N. Italy)

Sediment cores were collected at 5 stations in Lake Varese. They were analyzed for organic matter, N, P, organic C, Cd, Cr, Cu, Hg, Pb, Zn and PAHs. A sedimentological approach has been applied to estimate the ecological risk from identified pollutants.As in other eutrophic lakes in Northern Italy, this lake is also at considerable risk from heavy metal pollution. Cr, Cu and Cd showed the highest enrichment factors for the last 5 years, 23.4, 8.0 and 7.6 respectively. Other metals had enrichment factors ranging from 1 to 3. Fluoranthene was chosen as a representative PAH, derived from combustion products; its average value in surficial sediments ranged from 100 to 220 ng l^-1 dw. This compound can be a hazard to human health and aquatic life. An evaluation of radionuclide distributions after the recent Chernobyl accident in the USSR (¹³⁴Cs, ¹³⁷C s, ¹³¹I, ¹⁰⁶Ru) provided useful tracers to follow the cycling of pollutants bound to particulate matter in the aquatic ecosystem.     

C1q,a collagen-like complement subcomponent,in dermatosparactic cattle: its extracellular modification is not affected by lack of procollagen N-terminal proteinase (pN-proteinase)

C1q, a collagen-like complement protein, was purified from the serum of a ddermatosparactic calf which lacks procollagen N-terminal proteinase (pN-proteinase). The specific hemolytic activity of the serum Clq from the dermatosparactic animal was identical to that of C1q from a normal calf. Gel-filtration of serum from dermatosparactic calf, on Sepharose 6B, showed the presence of C1q-antigenic material at only one position which was identical to the elution position of normal bovine C1q. No differdence, under dissociating conditions, could be seen in the size of the chains of C1q in specific immunoprecipitates isolated from the sera of dermatosparactic and normal animals, as judged by polyacrylamidegel electrophoresis (PAGE) in the presence of sodium dodecyl sulfate (SDS). The C1q from the dermatosparactic animal showed the same N-terminal amino acid and typtic-digest peptide pattern on HPLC as C1q from the normal calf. These results strongly suggest that pN-proteinase is not involved in the extracellular processing of C1q.     

Regulation of Brain and Cerebrospinal Fluid Calcium by Brain Barrier Membranes Following Vitamin D-Related Chronic Hypo- and Hypercalcemia in Rats

Male Fischer-344 rats, 21 days old, were fed diets containing 0 (LOD), 2,200 (CONT), or 440,000 (HID) international units of vitamin D3 per kilogram for 12 weeks. [Ca] was measured in plasma, CSF, brain, and choroid plexus. In addition, 45Ca and 36Cl transfer coefficients (KCa and KCl) for uptake from blood into CSF and brain were determined. Although plasma ionized [Ca]s in LOD and HID rats were 50% and 136%, respectively, of values in CONT animals, CSF and brain [Ca]s ranged from only 85% to 110% of respective CONT values. Choroid plexus [Ca] was increased by 37% after HID diet, but was decreased only 10% after LOD. KCa values at CSF, parietal cortex, and pons-medulla were negatively correlated with plasma ionized [Ca], whereas KCl values at CSF and brain were not different between the diet groups. The findings demonstrate that central nervous system [Ca] is maintained during chronic hypo- or hypercalcemia by saturable transport of Ca at brain barrier membranes. This transport does not seem to involve modulation by 1,25-dihydroxyvitamin D3.     

Zinc tolerance in populations ofDeschampsia cespitosa (Gramineae) beneath electricity pylons

Patterns of zinc tolerance were examined in eightDeschampsia cespitosa (L.)Beauv. populations from normal and zinc-contaminated soils, using solution culture methods. Zinc-tolerant populations have evolved beneath pylons, and their tolerance patterns (degree, variance, heritability) vary. Tolerance is genetically based in all of them. In contrast to the cases of other species previously reported, some within-population differences are considerable, and may be due to both heterogeneity of the soils zinc contents, various gene combinations and gene recombinations between genotypes. One control population contains many tolerant plants, an original result which is discussed.     

Separation of insect hemolymph proteins by cascade-mode multi-affinity chromatography.

The hemolymph of the adult female Manduca sexta was fractionated by cascade-mode multi-affinity chromatography (CASMAC) on a main-line tandem column chain containing Zn(2+)-TED, T-gel, Ni(2+)-DPA, and phenylsepharose and a side-line column containing Zn(2+)-DPA. The technique separated some of the previously described major hemolymph proteins, and yielded a number of fractions with simple composition. Some of these fractions contained only less abundant proteins of Manduca hemolymph. Thus, it appears that CASMAC would be a very useful fractionation technique for purification and characterization of the minor proteins of insect hemolymph.     

Prospective theoretical and experimental study towards electrochemically grafted poly(N-vinyl-2-pyrrolidone) films on metallic surfaces

Quantum chemistry calculations of equilibrium geometry, atomic charges, dipole moment, and frontier orbital energies are carried out on model N-vinyl-2-pyrrolidone, its radical anion and cation, and three protonated derivatives. Attempts to obtain poly(N-vinyl-2-pyrrolidone) films grafted on nickel and platinum electrodes, respectively by cathodic and anodic polarizations, are reported. A thin, covering and insulating film is obtained on the Pt anode, as indicated by surface characterizations carried out with UPS and IRRAS spectroscopies. The fact that the film remains adherent to the metallic surface in spite of a permanent contact with an acetonitrile solution in which poly(N-vinyl-2-pyrrolidone) is soluble suggests that chemisorption has indeed been achieved.     

Effects of DNA binding and metal substitution on the dynamics of the GAL4 DNA-binding domain as studied by amide proton exchange.

Backbone amide proton exchange rates in the DNA-binding domain of GAL4 have been determined using 1H-15N heteronuclear correlation NMR spectroscopy. Three forms of the protein were studied-the native Zn-containing protein, the Cd-substituted protein, and a Zn-GAL4/DNA complex. Exchange rates in the Zn-containing protein are significantly slower than in the Cd-substituted protein. This shows that Cd-substituted GAL4 is destabilized relative to the native Zn-containing protein. Upon DNA binding, global retardation of amide proton exchange with solvent was observed, indicating that internal fluctuations of the DNA-recognition module are significantly reduced by the presence of DNA. In all forms of the protein, the internal dyad symmetry of the DNA-recognition module of GAL4 is reflected by the backbone amide proton exchange rates.