Enrichment of a Microbial Culture Capable of Reductive Debromination of the Flame Retardant Tetrabromobisphenol-A, and Identification of the Intermediate Metabolites Produced in the Process

Tetrabromobisphenol-A is a reactive flame retardant used in the production of many plastic polymers. In previous research, it was demonstrated that anaerobic microorganisms from contaminated sediment debrominate tetrabromobisphenol-A to bisphenol-A, but an enrichment culture was not established. The current study was carried out to identify the intermediate metabolites in this process and to determine the factors facilitating enrichment of debrominating microorganisms. During the enrichment process in an anaerobic semi-continuous batch reactor, tetrabromobisphenol-A debromination gradually slowed down with concurrent accumulation of three intermediate products. These compounds were tentatively identified using GC-MS as tri-, di-, and mono-brominated bisphenol-A. GC-MS and HPLC analyses showed one dominant metabolite of dibromobisphenol-A, and NMR analysis identified it as 2,2'-dibromobisphenol-A. Addition of sterile sediment(15% wt/wt) to the reactor stimulated debromination of tetrabromobisphenol-A.Furthermore, different solid amendments such as surface soil and pulverized gray chalk from the site subsurface (100 m below ground) were also stimulating agents.We conclude that organic matter is involved in stimulation since the stimulationeffect of the sediment, soil and gray chalk was abolished after it was heat-treatedto 550 °C. Our study suggests that the debrominating culture requires someorganic components found in the sediment, soil, and chalk in order to sustain activityand perhaps to survive. The possible mechanisms of stimulation by these solids arediscussed.     

Mullerian inhibiting substance inhibits breast cancer cell growth through an NFkappa B-mediated pathway

Müllerian inhibiting substance (MIS), a member of the transforming growth factor-beta superfamily, induces regression of the Müllerian duct in male embryos. In this report, we demonstrate MIS type II receptor expression in normal breast tissue and in human breast cancer cell lines, breast fibroadenoma, and ductal adenocarcinomas. MIS inhibited the growth of both estrogen receptor (ER)-positive T47D and ER-negative MDA-MB-231 breast cancer cell lines, suggesting a broader range of target tissues for MIS action. Inhibition of growth was manifested by an increase in the fraction of cells in the G(1) phase of the cell cycle and induction of apoptosis. Treatment of breast cancer cells with MIS activated the NFkappaB pathway and selectively up-regulated the immediate early gene IEX-1S, which, when overexpressed, inhibited breast cancer cell growth. Dominant negative IkappaBalpha expression ablated both MIS-mediated induction of IEX-1S and inhibition of growth, indicating that activation of the NFkappaB signaling pathway was required for these processes. These results identify the NFkappaB-mediated signaling pathway and a target gene for MIS action and suggest a putative role for the MIS ligand and its downstream interactors in the treatment of ER-positive as well as negative breast cancers.     

Light/dark cycles in the growth of the red microalga porphyridium sp

The effect of light/dark cycles on the growth of the red microalga Porphyridium sp. was studied in a tubular loop bioreactor with light/dark cycles of different frequencies and in two 35-L reactors: a bubble column reactor and an air-lift reactor. Photon flux densities were in the range of 50 to 300 μE m-2 s-1, and flow rates were 1 to 10 L min-1. Under conditions of low illumination and high flow rates, similar results were obtained for the bubble column and air-lift reactors. However, higher productivities-in terms of biomass and polysaccharide-were recorded in the air-lift reactor under high light intensity and low gas flow rates. The interactions of both photosynthesis and photoinhibition with the fluid dynamics in the bioreactors was taken as the main element that allowed us to interpret the differences in performance of the bubble column and the air-lift reactor. It is suggested that the cyclic distribution of dark periods in the air-lift reactor facilitates better recovery from the photoinhibition damage suffered by the cells. Copyright 1998 John Wiley & Sons, Inc.     

Proliferation of meristematic clusters in disposable presterilized plastic bioreactors for the large-scale micropropagation of plants

Summary Proliferation of meristematic clusters of several plants in an inexpensive airlift bioreactor system, consisting of a disposable presterilized light transmittable plastic film vessel is described. The optimal shape, size, and structural function of the disposable plastic bioreactor are based on the bubble column and airlift glass bioreactors. The disposable bioreactors are designed in a conical configuration with a single inoculation and harvest port and multiple use dispensing and mixing accessories. Shearing damage and foaming problems known to exist in bioreactors due to the plant's rigid cell wall and size were greatly reduced in the disposable plastic bioreactors. The disposable bioreactors were used for propagule proliferation and growth, using meristem and bud clusters of potato, fern, banana, and gladiolus. The clusters' biomass increased five-to eightfold over a period of 26–30 d, depending on the species. The clusters were separated mechanically by a chopper made of a grid of knives. The chopped propagules were inoculated to agar medium for further growth and developed into transplantable plants. In the case of gladiolus and potato, corms and tubers developed in a sucrose-elevated storage organ induction medium, respectively, after the initial formation of small shoots. The plantlets and storage organs were transplanted to an acclimation greenhouse and continued to grow with a 95–100% survival, depending on the species. Plant development was followed for a period of 16 wk in fern and 12–14 wk in potato, banana, and gladiolus and normal shoot and leaf growth was observed. The feasibility of large-scale liquid cultures for plant micropropagation is discussed.     

Computerized classification of Mediterranean vegetation using panchromatic aerial photographs

Abstract. Historical aerial photographs are an important source for data on medium- to long-term (10 - 50 yr) vegetation changes. Older photographs are panchromatic, and manual interpretation has traditionally been used to derive vegetation data from such photographs. We present a method for computerized analysis of panchromatic aerial photographs, which enables one to create high resolution, accurate vegetation maps. Our approach is exemplified using two aerial photographs (from 1964 and 1992) of a test area on Mt. Meron, Israel. Spatial resolution (pixel size) of the geo-rectified photos was 0.30 m and spatial accuracy (RMS error) ca. 1 m. An illumination adjustment prior to classification was found to be essential in reducing misclassification error rates. Two classification approaches were employed: a standard maximum-likelihood supervised classifier, and a modification of a supervised classification, which takes into account spectral properties of individual pixels as well as their neighbourhood characteristics. Accuracy of the maximum likelihood classification was 81 % in the 1992 image and 54 % in the 1964 image. The neighbour classifier increased accuracy to 89 % and 82 % respectively. The overall results suggest that computerized analysis of sequences of panchromatic aerial photographs may serve as a valuable tool for the quantification of medium-term vegetation changes.     

Glycosyl Phosphatidylinositol Anchor Biosynthesis Is Essential for Maintaining Epithelial Integrity during Caenorhabditis elegans Embryogenesis

Glycosylphosphatidylinositol (GPI) is a post-translational modification resulting in the attachment of modified proteins to the outer leaflet of the plasma membrane. Tissue culture experiments have shown GPI-anchored proteins (GPI-APs) to be targeted to the apical membrane of epithelial cells. However, the in vivo importance of this targeting has not been investigated since null mutations in GPI biosynthesis enzymes in mice result in very early embryonic lethality. Missense mutations in the human GPI biosynthesis enzyme pigv are associated with a multiple congenital malformation syndrome with a high frequency of Hirschsprung disease and renal anomalies. However, it is currently unknown how these phenotypes are linked to PIGV function. Here, we identify a temperature-sensitive hypomorphic allele of PIGV in Caenorhabditis elegans, pigv-1(qm34), enabling us to study the role of GPI-APs in development. At the restrictive temperature we found a 75% reduction in GPI-APs at the surface of embryonic cells. Consequently, ~80% of pigv-1(qm34) embryos arrested development during the elongation phase of morphogenesis, exhibiting internal cysts and/or surface ruptures. Closer examination of the defects revealed them all to be the result of breaches in epithelial tissues: cysts formed in the intestine and excretory canal, and ruptures occurred through epidermal cells, suggesting weakening of the epithelial membrane or membrane-cortex connection. Knockdown of piga-1, another GPI biosynthesis enzymes resulted in similar phenotypes. Importantly, fortifying the link between the apical membrane and actin cortex by overexpression of the ezrin/radixin/moesin ortholog ERM-1, significantly rescued cyst formation and ruptures in the pigv-1(qm34) mutant. In conclusion, we discovered GPI-APs play a critical role in maintaining the integrity of the epithelial tissues, allowing them to withstand the pressure and stresses of morphogenesis. Our findings may help to explain some of the phenotypes observed in human syndromes associated with pigv mutations.     

Cellular Changes during Renal Failure-Induced Inflammatory Aortic Valve Disease

Background

Aortic valve calcification (AVC) secondary to renal failure (RF) is an inflammation-regulated process, but its pathogenesis remains unknown. We sought to assess the cellular processes that are involved in the early phases of aortic valve disease using a unique animal model of RF-associated AVC.

Methods

Aortic valves were obtained from rats that were fed a uremia-inducing diet exclusively for 2, 3, 4, 5, and 6 weeks as well as from controls. Pathological examination of the valves included histological characterization, von Kossa staining, and antigen expression analyses.

Results

After 2 weeks, we noted a significant increase in urea and creatinine levels, reflecting RF. RF parameters exacerbated until the Week 5 and plateaued. Whereas no histological changes or calcification was observed in the valves of any study group, macrophage accumulation became apparent as early as 2 weeks after the diet was started and rose after 3 weeks. By western blot, osteoblast markers were expressed after 2 weeks on the diet and decreased after 6 weeks. Collagen 3 was up-regulated after 3 weeks, plateauing at 4 weeks, whereas collagen 1 levels peaked at 2 and 4 weeks. Fibronectin levels increased gradually until Week 5 and decreased at 6 weeks. We observed early activation of the ERK pathway, whereas other pathways remained unchanged.

Conclusions

We concluded that RF induces dramatic changes at the cellular level, including macrophage accumulation, activation of cell signaling pathway and extracellular matrix modification. These changes precede valve calcification and may increase propensity for calcification, and have to be investigated further.