Enrichment of mixed cultures capable of aerobic degradation of 1,2-dibromoethane.

1,2-dibromoethane (DBE) is a common environmental contaminant; it is potentially carcinogenic and has been detected in soil and groundwater supplies. Most of the biodegradation studies to date have been performed under anaerobic conditions or in the context of soil remediation, where the pollutant concentration was in the parts per billion range. In this work a mixed bacterial culture capable of complete aerobic mineralization of concentrations of DBE up to 1 g liter(-1) under well-controlled laboratory conditions was enriched. In order to verify biodegradation, formation of biodegradation products as well as the disappearance of DBE from the biological medium were measured. Complete mineralization was verified by measuring stoichiometric release of the biodegradation products. This mixed culture was found to be capable of degrading other halogenated compounds, including bromoethanol, the degradation of which has not been reported previously.     

Enzymatic hydrolysis of wood: an engineering assessment

Eucalyptus wood samples were delignified with HCl-catalysed acetic acid solutions under selected experimental conditions and treated with NaClO solutions. The solid residues obtained were employed as substrates for enzymatic hydrolysis. The NaClO concentration used in the pretreatment step, the liquor/solid ratio and the enzyme/substrate ratio were considered as operational variables. The experimental data allowed the development of generalized kinetic models which provided the necessary information for design calculations. The operational conditions were compared from an engineering viewpoint on the basis of economic estimates. Optimum conditions were established from these estimates.     

Detachment of transformed cells

A parallel-plate flow chamber was used to quantify the detachment of normal cloned rat embryo fibroblasts (CREF) fibroblasts,ras-transformed CREF fibroblasts (CREF T24), and CREF T24 fibroblasts transfected with a Krev/RAP1A suppressor gene (HK B1) from a confluent monolayer of normal CREF fibroblasts to determine if the expression patterns of CD44 variants (mol wt 110 and 140 kDa) corresponded with detachment properties and metastatic potential. In the detachment assay, known shear stresses ranging from 20–24 dyn/cm² were applied to the adherent cells and the number of cells detached from the monolayer after 180 s was determined. Results showed that cellular expression of CD44 variants correlated with the metastatic potential of the cells and with the cells’ ability to detach from a monolayer of normal cells. Western blot analysis showed a low level of expression of the CD44 variants in the normal cell line, CREF, and the lowly metastatic cell line, HK B1. Detachment studies showed a low percentage of detachment of both of these cell lines from a normal cell monolayer. Tumor-derived (HK B1-T) and lung nodule-derived (HK B1-M) cell lines were established and both formed tumors and metastasis with reduced latency periods as compared to HK B1, but still showed a markedly delayed latency period compared to the highly metastatic cell line, CREF T24. Both of these cell lines showed a higher expression of the CD44 variants as compared to CREF and HK B1, and detached easier than CREF and HK B1. CREF T24 showed a much higher level of expression of the variants and had a higher percentage detachment than all other cell lines. To further test the role of the CD44 variants in the ability of the cells to detach from the normal monolayer, CREF cells were transfected with a DNA construct that constitutively expresses the CD44 variants and the detachment properties of three randomly selected clones were studied. Clones 2 and 3 showed a low level of expression of the CD44 variants after transfection and detached from the normal monolayer similar to CREF. Clone 1 showed a high level of expression of the CD44 variants and the detachment of these cells was significantly higher than CREF. From these results, it is concluded that in the five cell lines studied, expression of the CD44 variants play a significant role in the ability of the cells to detach from a monolayer of normal cells. It is hypothesized that this detachment may be an important component of a cell’s ability to metastasize.     

Extraction and biodegradation of a toxic volatile organic compound (1,2-dichloroethane) from waste-water in a membrane bioreactor

An extractive membrane bioreactor has been used to treat a synthetic waste-water containing a toxic volatile organic compound, 1,2-dichloroethane (DCE). Biofilms growing on the surface of the membrane tubes biodegrade DCE while avoiding direct contact between the DCE and the aerating gas. This reduces air stripping by more than an order of magnitude (from 30–35% of the DCE entering the system to less than 1%) relative to conventional aerated bioreactors. Over 99% removal of DCE from a waste-water containing 1600 mg l^–1 of DCE was achieved at waste-water residence times of 0.75 h. Biodegradation was verified as the removal mechanism through measurements of CO₂ and chloride ion evolution in the bioreactor. No DCE was detected in the biomedium over the operating period. The diffusion-reaction phenomena occurring in the biofilm have been described by a mathematical model, which provides calculated solutions that support the experimental results by predicting that all DCE is biodegraded within the biofilm. Experimentally, however, the rate of DCE degradation in the biofilm was found to be independent of O₂ concentration, while the model predictions point to O₂ being limiting.     

Imprinting mutations suggested by abnormal DNA methylation patterns in familial Angelman and Prader-Willi syndromes.

The D15S9 and D15S63 loci in the Prader-Willi/Angelman syndrome region on chromosome 15 are subject to parent-of-origin-specific DNA methylation. We have found two Prader-Willi syndrome families in which the patients carry a maternal methylation imprint on the paternal chromosome. In one of these families, the patients have a small deletion encompassing the gene for the small nuclear ribonucleoprotein polypeptide N, which maps 130 kb telomeric to D15S63. Furthermore, we have identified a pair of nondeletion Angelman syndrome sibs and two isolated Angelman syndrome patients who carry a paternal methylation imprint on the maternal chromosome. These Angelman and Prader-Willi syndrome patients may have a defect in the imprinting process in 15q11-13. We propose a model in which a cis-acting mutation prevents the resetting of the imprinting signal in the germ line and thus disturbs the expression of imprinted genes in this region.     

Machado-Joseph Disease in Pedigrees of Azorean descent is Linked to Chromosome 14

A locus for Machado-Joseph disease (MJD) has recently been mapped to a 30-cM region of chromosome 14q in five pedigrees of Japanese descent. MJD is a clinically pleomorphic neurodegenerative disease that was originally described in subjects of Azorean descent. In light of the nonallelic heterogeneity in other inherited spinocere-bellar ataxias, we were interested to determine if the MJD phenotype in Japanese and Azorean pedigrees arose from mutations at the same locus. We provide evidence that MJD in five pedigrees of Azorean descent is also linked to chromosome 14q in an 18-cM region between the markers D14S67 and AACT (multipoint lod score +7.00 near D14S81). We also report molecular evidence for homozy-gosity at the MJD locus in an MJD-affected subject with severe, early-onset symptoms. These observations confirm the initial report of linkage of MJD to chromosome 14; suggest that MJD in Japanese and Azorean subjects may represent allelic or identical mutations at the same locus; and provide one possible explanation (MJD gene dosage) for the observed phenotypic heterogeneity in this disease.     

Keraladiaptomus rangareddyi a new genus and new species of Diaptominae (Copepoda,Calanoida, Diaptomidae) from a temporary pond in Mattam,Kerala State,India

Calanoid copepods, belonging to the new genus and species Keraladiaptomus rangareddyi, were collected from temporary ponds in Kerala State, India. The new genus belongs to the family Diaptomidae, subfamily Diaptominae. It is described in detail and its affinity to the related genera, Arctodiaptomus Kiefer, 1932 and Eodiaptomus Kiefer, 1932, discussed.     

Diel variability in catch rate of juvenile flatfish on two small nursery grounds (Port Erin Bay, Isle of Man and Porto Pirn Bay, Faial, Azores)

Variation in beach seine catches was examined in two juvenile flatfish populations (Port Erin, Isle of Man and Porto Pirn, Azores) to determine the importance of diel cycles while controlling for tidal rhythmicity. At Port Erin sampling was undertaken at each low water on consecutive days over a 2-week period in May/June and September 1991. There was no periodicity in the catches of plaice ( Pleuronectes platessa ) in May/June, but in September catches were higher at night. Other flatfish species ( Limanda limanda, Pleuronectes flesus, Scophthalmus maximus and S. rhombus ) sampled at Port Erin were nocturnal. At Porto Pirn, Azores, fish were sampled over 24 h each month from July 1989 to June 1990 and at each low water over a 2-week period in July 1991. The only flatfish species present was Bothuspodas , which had a diurnal pattern in catches over a 1-year period. Sampling at low water in July gave high catches at both midnight and midday.     

Induction of Nitric Oxide Synthase in Rat C6 Glioma Cells

Abstract: We have examined the induction of nitric oxide syhthase (NOS) activity in the rat astrocyte-derived C6 glioma cell line. In contrast to the previous results with primary astrocyte cultures, incubation of C6 cells with bacterial endotoxin lipopolysaccharide (LPS; 1 μg/ml for 24 h) did not stimulate NO₂ production. However, addition of either tumor necrosis factor-a (TNF-α) or interferon-γ (IFN-γ), cytokines that by themselves had no effect on NOS activity, imparted LPS responsiveness onto these cells in a dose-dependent manner (EC₅₀ values of 39 ng/ml of TNF-α and 9.4 U/ml of IFN-γ), and the effect of TNF-α could be further potentiated (twofold) by the presence of interleukin-1β. The simultaneous presence of TNF-α and IFN-γ yielded a greater response than either cytokine alone; however, the respective EC₅₀ values were not affected. A cytoplasmic extract from induced C6 cells catalyzed the Ca²⁺-independent conversion of l -arginine to l - citrulline, with an apparent K _m of 51.2 n M , and this activity could be blocked by l -arginine analogues in the potency order amino > methyl > nitroarginine. Immunoblot analysis revealed an apparent molecular mass of 125 kDa for the NOS protein induced in C6 cells. These results indicate that the combination of LPS plus cytokines can induce NOS activity in C6 glioma cells with properties similar to those of the enzyme expressed in primary astrocyte cultures.