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.     

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.     

Early helper T-cell dysfunction in simian immunodeficiency virus but not in human immunodeficiency virus type-2-infected macaques

Both naive and vaccinated macaques acquired a virus-specific proliferative helper T-cell reactivity in response to infection with the nonpathogenic human immunodeficiency virus type 2 (HIV-2). In contrast, macaques infected with the pathogenic simian immunodeficiency virus of the macaque strain (SIV_mac) did not develop a helper T-cell response. Furthermore, a vaccine-induced preexisting T-cell reactivity was abrogated after SIV_mac infection in vaccine failures. These differences may reflect the different pathogenicity of the two closely related viruses.     

Comparison of RAPD and RFLP genetic markers in determining genetic similarity among Brassica oleracea L. genotypes

Genetic similarity among 45 Brassica Oleracea genotypes was compared using two molecular markers, random amplified polymorphic DNA (RAPD) and restriction fragment length polymorphisms (RFLPs). The genotypes included 37 broccolis (var. italica), five cauliflowers (var. botrytis) and three cabbages (var. capitata) which represented a wide range of commercially-available germplasm, and included open-pollinated cultivars, commercial hybrids, and inbred parents of hybrid cultivars. Fifty-six polymorphic RFLP bands and 181 polymorphic RAPD bands were generated using 15 random cDNA probes and 62 10-mer primers, respectively. The objectives were to compare RFLP and RAPD markers with regard to their (1) sampling variance, (2) rank correlations of genetic distance among sub-samples, and (3) inheritance. A bootstrap procedure was used to generate 200 random samples of size n (n=2,3,5,... 55) independently from the RAPD and RFLP data sets. The coefficient of variance (CV) was estimated for each sample. Pooled regressions of the coefficient of variance on bootstrap sample size indicated that the rate of decrease in CV with increasing sample size was the same for RFLPs and RAPDs. The rank correlation between the Nei-Li genetic similarity values for all pairs of genotypes (990) based on RFLP and RAPD data was 0.745. Differences were observed between the RFLP and RAPD dendrograms of the 45 genotypes. Overlap in the distributions of rank correlations between independent sub-samples from the RAPD data set, compared to correlations between RFLP and RAPD sub-samples, suggest that observed differences in estimation of genetic similarity between RAPDs and RFLPs is largely due to sampling error rather than due to DNA-based differences in how RAPDs and RFLPs reveal polymorphisms. A crossing algorithm was used to generate hypothetical banding patterns of hybrids based on the genotypes of the parents. The results of this study indicate that RAPDs provide a level of resolution equivalent to RFLPs for detemination of the genetic relationships among genotypes.     

Variability of the env gene in cynomolgus macaques persistently infected with human immunodeficiency virus type 2 strain ben.

The sequence variability of distinct regions of the proviral env gene of human immunodeficiency virus type 2 strain ben (HIV-2ben) isolated sequentially over 3 to 4 years from six experimentally infected macaques was studied. The regions investigated were homologous to the V1, V2, V3, V4, V5, and V7 hypervariable regions identified in the env genes of HIV-1 and simian immunodeficiency virus SIVmac, respectively. In contrast to findings with HIV-1 and SIVmac, the V1- and V2-homologous regions were found to be highly conserved during the course of the HIV-2ben infection in macaques. The V3-homologous region showed a degree of variation comparable to that of HIV-1 but not of SIV. In the V4-, V5-, and V7-homologous regions, mutation hot spots were detected in most reisolates of the infected monkeys. Most of these mutations occurred during the first 10 weeks after infection. After 50 weeks, new mutations were rarely detected. At most mutation sites, a dynamic equilibrium between the mutated viral isotype and the infecting predominant wild type was present. This equilibrium might prevent an accumulation of mutations in isolates later in the course of infection.     

Regulation of circulating levels of the crustacean hyperglycemic hormone: evidence for a dual feedback control system

The effects of glutamate, aspartate, glycine, proline, alanine, taurine, glycerol, glucose and lactate injections on the haemolymph levels of the crustancean hyperglycemic hormone and/or glucose and lactate in the shore crab, Carcinus maenas, were investigated. Only glucose and lactate caused significant changes of hyperglycaemic hormone levels. Glucose injections resulted in a drop of both hormone and lactate, while lactate had an opposite effect, i.e. it raised both crustacean hormone and glucose levels. The results suggest that during increases in glycolytic flux, lactate may cause a release of hormone by a positive feedback mechanism. The hormone would then stimulate glycogenolysis, thus increasing glucose availability. If more glucose is released than is metabolized, excess glucose may leak from the cells and suppress crustancean hyperglycemic hormone release from the X-organ/sinus gland complex by negative feedback.Abbreviations ABTS 2,2-azino-bis (3-ethylbenzthiazoline sulphonic acid) - ANOVA one-way analysis of variance - BSA bovine serum albumin - BW body weight - CHH crustacean hyperglycemic hormone - ELISA cnzyme-liked immunosorbent assay - GIH gonadinhibiting hormone - IgG immunoglobin G - MIH moult-inhibiting hormone - MTGXO medulla terminalis X-organ - PB sodium phosphate buffer - PBS phosphate buffered saline - Pi inorganic phosphate - XO-SG X-organ-sinus gland complex     

A novel bioreactor system for the destruction of volatile organic compounds

The biological treatment of waste-waters containing 1,2-dichloroethane (DCE) in conventional bioreactors results in air-stripping of DCE. In the present work, a novel bioreactor system intended to overcome this problem has been developed for the treatment of a synthetically concocted DCE-containing waste-water (1000 mg DCE l^–1). The operation of a conventional air-lift bioreactor at a waste-water flow rate of 0.24 l h^–1 led to 33% of the DCE supplied to the reactor being lost to the exit gas stream. The use of the novel enclosed system, operated with a recycling O₂ sparge instead of air, resulted in negligible air-stripping at the same waste-water flow rate. A control system was implemented to add O₂ as required to maintain the pressure of the recycle gas stream, and a scrubber removed the CO₂ produced. Over 99% of DCE supplied was biodegraded during operation of this system, and virtually all carbon entering the system was evolved as CO₂. Correspondence to: A. G. Livingston Correspondence to: A. G. Livingston     

Synaptic patterns of rye B chromosomes. II. The effect of the standard B chromosomes on the pairing of the A set

In order to elucidate the possible effects of rye B chromosomes (Bs) on synapsis and metaphase-I associations of the A set, a comparative study between pachytene and metaphase-I-cells of rye plants carrying different numbers of Bs (0–8) has been carried out. The number of Bs was found to be positively correlated with the frequency of synaptic irregularities of the A set, i.e. multivalents and foldback pairing, and with the frequency of pachytene interlockings. It is proposed that interlockings are the origin of these irregularities because both appeared in close proximity in many nuclei. Examples of A-B pairing are described. The frequency of synaptic abnormalities seems to be unrelated to the mean of A chromosome-bound arms at metaphase I.