Selenium reduction by a denitrifying consortium

A denitrifying bacterial consortium obtained from the Pullman, Washington wastewater treatment facility was enriched under denitrifying conditions and its ability to reduce selenite and selenate was studied. Replicate experiments at two different experimental conditions were performed. All experiments were performed under electron-acceptor limiting conditions, with acetate as the carbon source and nitrate the electron acceptor. In the first set of experiments, selenite was present, whereas, in the second set, selenate was added. A significant lag period of approximately 150 h was necessary before selenite or selenate reduction was observed. During this lag period, nitrate and nitrite use was observed. Once selenite or selenate reduction had started, nitrate and nitrite reduction was concomitant with selenium species reduction. Trace amounts of selenite were detected during the selenate reduction study. Analysis of the data indicates that, once selenium species reduction was induced, the rate of reduction was proportional to the selenium species concentration and to the biomass concentration. Furthermore, at similar biomass and contaminant concentrations, selenite reduction is approximately four times faster than selenate reduction. Copyright 1999 John Wiley & Sons, Inc.     

Molecular study of the rat liver NADH: Cytochrome c oxidoreductase complex during development and aging

The mechanisms involved in ageing are yet to be fully understood but it is thought that changes produced in energy transfer pathways occurring in the mitochondria may be responsible for the lack of energy typical of the later stages of life. The aim of the present investigation was to determine the enzymatic activity of the liver NADH cytochrome c oxidorectuctase complex (Complex I-III) in mitochondria isolated from the liver of rats of 3 different age groups: lactating, animals (15-17 days), adult females (3-5 months) and old animals (26-30 months). The activities of the unbound Complexes I and III were also determined.An increase in Complex I-III activity was detected during development (142 ± 10 vs. 447 ± 23 mol cyt. c/mg/min, p < 0.001) ang ageing (447 ± 23 vs. 713 ± 45 mol cyt. c/mg//min, p < 0.001). However, unbound Complex I showed a reduction in activity during the ageing period whilst Complex III activity moderately increased. Immunological studies indicated only a moderate increase in the amount of Complex I-III and studies on the purified complex suggested that the increase in activity was due to effects other than an increase in enzyme quantity. The analysis of protein bands and the quantification of prosthetic groups showed particular reductions in the relative concentrations of Complex I subunits including the 51 kDa unit, which binds FMN, confirmed by a similar reduction in levels of the nucleotide. In contrast, 4 of the 5 subunits which increased during the lifetime of the animals corresponded to those of Complex III. These subunits are responsible for the binding of catalytic groups. The results suggest that, in addition to the increase in the amount of enzyme, binding factors between Complexes I and III may also play an important role in the observed increase in Complex I-III activity.     

Expansion and divergence of the GH locus between spider monkey and chimpanzee

Growth hormone (GH) has been previously described as showing distinct evolutionary stories between primates and other mammals. A burst of changes and successive amplification events took place in the primate lineage giving rise to a multigene family in the three Anthropoidea lineages. Polymerase chain reaction (PCR) was used to obtain the genes and the intergenic regions comprising the GH loci of the spider monkey (Ateles geoffroyi), a New-World primate, and of the chimpanzee (Pan troglodytes), an ape. The intergenic sequences of both species were screened by hybridization to detect copies of the Alu family, which have been implicated in the formation of the human GH locus. The GH locus of the spider monkey contains at least six GH-related genes, four of them were cloned. Likewise, five short intergenic sequences of approximately 3 kb were amplified and cloned. On the other hand, in the chimpanzee four new placental lactogen (PL) genes as well as four intergenic regions were amplified. Consequently, in this ape, six genes (two GHs, previously obtained, and four PLs) are clustered, separated by intergenic sequences of different lengths (two short ones of about 5 kb, and at least two long ones between 9 and 13 kb). The presence of Alu sequences within the intergenic regions of both GH loci corroborates the current hypothesis that they acted as a driving force for the locus expansion. GH sequence comparisons reveal that several gene-conversion events might have occurred during the formation of this genome region, which has undergone independent evolution in the three Anthropoidea branches. To establish the GH's evolutionary history may prove to be a difficult task due to these gene-conversion events.     

Helminths from the fish Dormitator maculatus (Osteichthyes: Eleotridae) from Alvarado, Veracruz, Mexico

Dormirator maculatus (n=184) was collected in the Alvarado Lagoon, Mexico during a year period (Oct. 1993-1994). In the helminthologic review, the presence of Clinostomum complanatum (82.3%), Neoechinorhynchus golvani (76.1%), Spiroxys sp. (21.3 %), and Camallanus sp. (6.2%) was registered. Reduction of the hematocrit caused by such infection is significant (t, a= 0.05).     

A chemoattractant role for NT-3 in proprioceptive axon guidance

Neurotrophin-3 (NT-3) is required for proprioceptive neuron survival. Deletion of the proapoptotic gene Bax in NT-3 knockout mice rescues these neurons and allows for examination of their axon growth in the absence of NT-3 signaling. TrkC-positive peripheral and central axons from dorsal root ganglia follow proper trajectories and arrive in close proximity to their targets but fail to innervate them. Peripherally, muscle spindles are absent and TrkC-positive axons do not enter their target muscles. Centrally, proprioceptive axons branch in ectopic regions of the spinal cord, even crossing the midline. In vitro assays reveal chemoattractant effects of NT-3 on dorsal root ganglion axons. Our results show that survival factor NT-3 acts as a short-distance axon guidance molecule for muscle sensory afferents as they approach their proper targets.     

Depolarization-induced ERK phosphorylation depends on the cytosolic Ca2+ level rather than on the Ca2+ channel subtype of chromaffin cells

The contribution of Ca2+ entry through different voltage-activated Ca2+ channel (VACC) subtypes to the phosphorylation of extracellular signal regulated kinase (ERK) was examined in bovine adrenal-medullary chromaffin cells. High K+ depolarization (40 mM, 3 min) induced ERK phosphorylation, an effect that was inhibited by specific mitogen-activated protein kinase kinase inhibitors. By using selective inhibitors, we observed that depolarization-induced ERK phosphorylation completely depended on protein kinase C-alpha (PKC-alpha), but not on Ca2+/calmodulin-dependent protein kinase nor cyclic AMP-dependent protein kinase. Blockade of L-type Ca2+ channels by 3 microm furnidipine, or blockade of N channels by 1 micromomega-conotoxin GVIA reduced ERK phosphorylation by 70%, while the inhibition of P/Q channels by 1 micromomega-agatoxin IVA only caused a 40% reduction. The simultaneous blockade of L and N, or P/Q and N channels completely abolished this response, yet 23% ERK phosphorylation remained when L and P/Q channels were simultaneously blocked. Confocal imaging of cytosolic Ca2+ elevations elicited by 40 mm K+, showed that Ca2+ levels increased throughout the entire cytosol, both in the presence and the absence of Ca2+ channel blockers. Fifty-eight percent of the fluorescence rise depended on Ca2+ entering through N channels. Thus, ERK phosphorylation seems to depend on a critical level of Ca2+ in the cytosol rather than on activation of a given Ca2+ channel subtype.     

Hepatitis B surface antigen immunopurification using a plant-derived specific antibody produced in large scale

This paper provides an evaluation of a plant-derived HBsAg-specific antibody in the immunopurification of the recombinant HBsAg for vaccine purposes. This plant-derived antibody was obtained from different batches of 100-200kg of tobacco leaves and coupled to Sepharose CL-4B with high efficiency. The plant-derived antibody immunoaffinity matrix purification behavior (elution capacity, antigen purity, purification cycles, and ligand leakage) was comparable to that of its mouse-derived monoclonal antibody homolog. This result supports the feasibility of using this plant-derived antibody for the immunopurification of the Hepatitis B surface antigen for human use, opening a new possibility to overcome the constrain of monoclonal antibody production in mice.     

Paternally inherited markers in bovine hybrid populations

The genetic integrity of crossfertile bovine- or cattle-like species may be endangered by species hybridization. Previously, amplified fragment length polymorphism, satellite fragment length polymorphism and microsatellite assays have been used to analyze the species composition of nuclear DNA in taurine cattle, zebu, banteng and bison populations, while mitochondrial DNA reveals the origin of the maternal lineages. Here, we describe species-specific markers of the paternally transmitted Y-chromosome for the direct detection of male-mediated introgression. Convenient PCR-restriction fragment length polymorphism and competitive PCR assays are shown to differentiate the Y-chromosomes of taurine cattle, American bison and European bison, and to detect the banteng origin of Indonesian Madura and Bali cattle bulls.     

Excretion and measurement of estradiol and progesterone metabolites in the feces and urine of female squirrel monkeys (Saimiri sciureus)

The first objective of the present study was to determine the metabolic form and rate of excretion of ovarian hormone metabolites in the urine and feces of female squirrel monkeys injected with radiolabeled progesterone (Po) and estradiol. The major portion of the urinary metabolites of both hormones was excreted within 16-24 hr post-injection. Estrogen and Po isotopes in feces exhibited an excretion peak at 16 hr post-injection. The majority of recovered radiolabel of both hormones was excreted in feces. Chromatographic separation of fecal extractions indicated that the major estrogen metabolites in feces are in the free as opposed to the conjugated form. The radioactivity and immunoreactivity for estrone and estradiol (E(1) and E(2), respectively) in eluates of fecal samples subjected to celite co-chromatography indicated that both free E(1) and E(2) exist as excretion products in the feces of female squirrel monkeys. The major radioactive peaks for Po metabolites showed peaks in the elution profile at or very near the Po standard, and corresponded with the celite co-chromatography elution profile of Po standard when subjected to enzyme immunoassay (EIA). The second objective was to validate the application of EIA systems to measure fecal metabolites. Reproductive events of one female squirrel monkey across one annual reproductive cycle are described using the endocrine profile generated from fecal steroid assays. Examination of this profile confirmed that longitudinal fecal sampling and steroid hormone metabolite measurement in feces was not only feasible and practical, but accurately detected known reproductive events as well.