How Non-native Species in Lake Erie Influence Trophic Transfer of Mercury and Lead to Top Predators

Lake Erie's food web has been dramatically modified by exotic species. Both exotic dreissenid mussels and the round goby Neogobius melanastomus have shifted the food web from a pelagicbased to a benthic-based one, potentially creating a new pathway for contaminant transfer to top predators. Before the invasion of round gobies, few predators of dreissenids occurred in Lake Erie, allowing contaminants to be confined to these benthic organisms. The invasion of the round goby has produced a new pathway through which these contaminants can enter the food web. To characterize heavy-metal transfer through this new food web and to assess risk to humans, water, surficial sediment, dreissenid, round goby, and smallmouth bass Micropterus dolomieui samples were collected at three sites during summers, 2002 and 2003, and analyzed for total lead (Pb), total mercury (Hg), and methyl mercury (MeHg). In addition, we compared smallmouth bass Pb and Hg concentrations to those measured in 1993/1994, before round gobies were prevalent. Pb biodiminished and MeHg biomagnified through the food web to smallmouth bass; patterns were similar among our three sites. Total Pb concentrations in smallmouth bass were higher before the incorporation of round gobies into their diet. We attributed this decline to changes in food web structure, changes in contaminant burdens in prey, or declines in sediment Pb concentrations in Lake Erie. By comparison, Hg concentrations in smallmouth bass changed little, before and after the round goby invasion, possibly due to a shift in diet that increased growth. Despite a decline in sediment Hg concentrations in Lake Erie, smallmouth bass continued to accumulate Hg at historical rates possibly because of their high consumption rates of benthivorous round gobies. As smallmouth bass continue to consume round gobies during their lives, their Hg concentrations may well continue to increase, potentially increasing the risk of Hg contamination to humans.     

The distribution of nutrient elements in cell wall and other fractions of the herbage of some grasses and legumes

The distribution of 10 nutrient elements was assessed in three fractions of herbage samples of perennial ryegrass, tall fescue, white clover and lucerne. The cell wall fraction, prepared by mechanical disintegration of undried material, contained the following proportions of the total herbage content of the major elements: N, 2.9–16.4%; P, 3.0–6.9%; S, 3.6–17.2%; Ca, 11.3–51.8%; Mg. 6.4–27.6% and K, 0.1–1.7%. Substantial though more variable proportions of the trace element cations, Fe, Mn, Zn and Cu were also present in the cell wall fraction. The extent to which the elements were soluble in water was assessed by analysis of the water-insoluble fraction prepared from freeze-dried samples of each herbage. The proportions of the total herbage content of the major elements soluble in water were: N, 30–57%; P, 80–92%; S, 35–71%; Ca, 48–69%; Mg. 65–83% and K, 90–96%. With the trace element cations the proportions soluble in water were more variable, though they were generally less than 70% of the total. The extent to which the various elements were soluble in 80% aqueous ethanol was assessed by analysis of the insoluble fraction prepared from freeze-dried materials. With each of the major elements, smaller proportions of the total herbage content were soluble in 80% ethanol than in water, which may reflect in part the lower solubility of proteins and pectin. With the trace element cations, the differences in solubility between 80% ethanol and water were generally small and inconsistent.     

Targeting T cells against brain tumors with a bispecific ligand-antibody conjugate

Haemophilus influenzae is a bacterium of medical interest of which the entire genome has been sequenced. The proteome of the microorganism has been analyzed by two-dimensional gel electrophoresis, during which immobilized pH 3-10 gradient strips were used and approximately 300 proteins were identified. In order to detect additional, basic proteins, we analyzed the soluble protein fraction of H. influenzae and the proteins of fractions collected from affinity chromatography on heparin, by two-dimensional gel electrophoresis, using for the first-dimensional separation immobilized pH gradient strips comprising the pH region of 6-11. The protein spots were analyzed by matrix-assisted laser desorption ionization-mass spectrometry. One hundred and two proteins were identified, of which 58 were identified for the first time. A large percentage of the basic proteins represent nucleic acid binding and, in particular, ribosomal proteins. The locations of the identified basic proteins of H. influenzae are indicated in a two-dimensional map.     

Protective effect of Picroliv from Picrorhiza kurroa against Leishmania donovani infections in Mesocricetus auratus

The prevalent drugs for treatment of kala azar viz. sodium stibogluconate (SSG) and pentamidine cause severe toxic side effects and acute immunosuppression in the treated individuals. Picroliv, a standardized mixture of iridoid glycosides, prepared from the alcoholic extract of the root and rhizome of Picrorhiza kurroa has shown strong hepatoprotective activity against several models of hepatotoxicity. Therefore, the present study was undertaken with an objective to study the effects of Picroliv (12.5 mg/kg x 7 days oral) alone and in combination with SSG on parasitemia, lipid peroxidation and hepatic marker enzymes of golden hamsters during Leishmania donovani infection. The results indicated a marked hepatoprotective effect of Picroliv in terms of biochemical markers, and a significant antileishmanial activity implying that it can be utilized as an adjunct to chemotherapy or in combination therapy of kala azar along with sodium stibogluconate, thus enhancing the efficacy of antileishmanials.     

Slipped capital femoral epiphysis associated with radiation therapy

We reviewed 32 children with 41 radiation-therapy associated slipped capital femoral epiphyses (RTASCFE). Ten were from the authors' institutions and 22 from the literature. Gender distribution was equal. The age at diagnosis of the malignancy was 4.3 +/- 3.1 years; the amount of radiation was 4,240 +/- 1,445 rads. Children with RTASCFE presented younger (10.4 +/- 3.2 years) than a routine SCFE. The average symptom duration was 5 +/- 6 months. Children with RTASCFE are usually thin (median weight, 10th percentile) in contrast to children with typical SCFE, who are usually obese (<95th percentile). The majority (82%) of the slips were mild, compared to routine SCFEs (approximately 50%); 28% were bilateral. There was a positive linear relationship between the age at presentation of the SCFE and the age at diagnosis of the malignancy; there was a negative linear relationship between the age at presentation of the SCFE and the amount of radiation therapy.     

Studies on miscibility of blends of ethylene methyl acrylate and polydimethyl siloxane rubber

Blends of ethylene methyl acrylate (EMA) and poly(dimethylsiloxane) rubber (PDMS) are demonstrated to be miscible. The miscibility results in a single and composition-dependent glass transition temperature. IR spectra of the blends provide direct evidence of chemical reaction between EMA and PDMS rubber.     

Characterization of the 6'-N-aminoglycoside acetyltransferase gene aac(6')-Iq from the integron of a natural multiresistance plasmid

The nucleotide sequence of a newly identified amikacin resistance gene, aac(6')-Iq (551 bp), is reported. It has 68.4 and 94.4% homology with the aac(6')-Ia gene and the recently described aac(6')-Ip gene, respectively. Analysis of its flanking sequences indicated that it is in the first cassette of a class I integron and has an attC site (59-base element) 108 bp in length.