Biodegradation of crosslinked acrylic polymers by a white-rot fungus

Two synthetic superabsorbent crosslinked acrylic polymers were mineralized by the white-rot fungusPhanerochaete chrysosporium. The amount of polymer converted to CO₂ increased as the amount of polymer added to the cultures increased. In the presence of sufficiently large amounts of the superabsorbents, such that all of the culture fluid was absorbed and a gelatinous matrix was formed, the fungus still grew and mineralization was observed. Neither the polymers, nor their degradation products were toxic to the fungus. While the rates of mineralization were low, all of the polymers incubated in the liquid fungal cultures were completely depolymerized to water soluble products within 15–18 days. The depolymerization of the polymers was observed only in nitrogen limited cultures of the fungus which secrete the lignin degradation system, however, the water soluble products of depolymerization were mineralized in both nutrient limited and sufficient cultures of the fungus. The rate of mineralization of the depolymerized metabolites was more than two times greater in nutrient sufficient cultures. Following longer incubation periods, most (> 80 %) of the radioactivity was recovered in the fungal mycelial mat suggesting that carbon of the polymer had been converted to fungal metabolites.     

Rapid growth of clones of the red alga Chondrus crispus: applications in assays of toxic substances and in physiological studies

Growth rates of excised apical segments from three Chondrus crispus Stackhouse clones were rapid, reproducible and easily measured using simple equipment. Clonal segments exhibited a high degree of phenotypic stability, with coefficients of variation in growth rates being typically less than 5%. Sensitivity of the assay was demonstrated using 24-h pulses of the toxicants Cu²⁺ (10 to 150 ppb) and the molluscicide Bayluscide (100 to 500 ppb). As a further demonstration of applicability of this assay system, growth rates were measured over two consecutive 24-h photoperiods using a normally pigmented red gametophytic clone and a green colored mutant derived from it. Growth rates were highest in the first hours of the light phase for both clones, with growth of the green mutant being consistently inferior to that of the normally pigmented one. Significant changes were measured with intervals as short as 4 h using only five apical segments for each treatment. The C. crispus assay described is sensitive, relatively rapid, and statistically robust when applied to toxicant testing in seawater and to physiological studies.     

Stability of a Coal Waste Artificial Reef

The feasibility of using U.K. coal-fired power station waste materials for artificial reef production is being examined. in June, 1989, an experimental artificial reef was constructed in Poole Bay, off the central south coast of the U.K., using three different mixtures of pulverised fuel ash (PFA), flue gas desulphurisation (FGD) gypsum and slurry, stabilized with cement and formed into blocks. Fifty tonnes of 40 × 20 × 20 cm blocks were formed into eight conical reef units replicating three different PFA/gypsum mixtures and one concrete control. the reef structure is 10m below chart datum on a flat sandy sea-bed.

Combustion of coal concentrates the heavy metal content in the resultant ash. the purpose of stabilization of the ash as blocks is twofold: to immobilize heavy metals (or other components) and to provide hard substratum for the attachment of organisms. to examine the effectiveness of this stabilization and hence the environmental compatibility of the block materials, heavy metal (Cd, Cr, Cu, Pb, Mn, Ni, Zn) content of the blocks has been monitored routinely over two years, to determine leaching rates. Sectional profiles indicate partial replacement of calcium content by magnesium. Associated with this there has also been some redistribution of heavy metals. Only in the case of cadmium has there been a detectable loss from the surface of blocks. Chromium and manganese concentrations appear to have increased. the metal content of the reef epibiota (including ascidians, Ascidia mentula; hydroids, Halecium spp.; bryozoans, Bugula spp. and red algae) growing on the ash blocks has been compared to that of epibiota attached to the concrete controls and surrounding sea-bed. to date no evidence of excess bioaccumulation of metals has been detected.

The physical integrity of the ash reef blocks has been maintained. There is evidence that the blocks are increasing in compressive strength.

An indication of the fishery enhancement potential of the experimental structure is given by the presence of eight commercially fished species (crustaceans and molluscs) including lobsters (Homarus gammarus).     

Importance of eating habits and sample size in the estimation of environmental mercury contamination using biological indicators

The importance of eating habits and the number of fish sampled in the estimation of mercury environmental contamination through biological indicators was studied. The species used were one with piscivorous habits (Anguilla anguilla) and another with omnivorous habits (Ciprinus carpio). From one original sample for each species, randomized samples were generated using the subroutine GGSRS from the mathematics library IMSL, and later the statistical significance of Pearson's correlation coefficient for the relationship between fish weight and mercury concentrations in muscle was obtained for each random sample. The results show that the use of omnivorous species such as Ciprinus carpio as a biological indicator of contamination enables us to carry out estimations with a greater degree of confidence than when piscivorous species such as Anguilla anguilla are used.     

Mikrobielle Sanierung von 2,4,6-Trinitrotoluol (TNT) kontaminierten Böden

Within the limits of a feasability study abouton-site bioremediation methods for TNT-contaminated soils, composting was chosen as a very promising and cheap method. This method was critically compared with those described in the literature and was primarily rated under ecotoxicological aspects. The investigated location is the former munition plant «Tanne» in the aerea of Clausthal-Zellerfeld in Lower Saxony, Germany. To estimate the autochtonic microflora, we assessed the number of aerobic heterotrophic bacteria and determined their respiration activity in soils. In addition, we isolated bacteria and examined their capacity to metabolize TNTin vitro. Both the amount of autochtonic microrganisms (4.7×10⁸ to 1.2×10¹⁰ colony forming units (cfu)/kg dryweight) as well as their respiration activity did not correlate with the concentrations of nitrotoluenes in the soils. With high contaminated soil (20 g TNT/kg dry weight) we carried out a small compost in the range of 10 liters. During 28 days of composting TNT-concentration decrease over 90% and only minor amounts of monoaminodinitrotoluenes were generated. However, an acidic pretreatment of the compost material at the end of the reaction showed that TNT could be partially resolved under these extreme conditions and that an ecotoxicological risk may still exist. Possible changes in the realization of the composting process in order to make sure that the contaminants are savely bound to the humin matrix are discussed.     

Seasonal fluctuations in sand temperature: effects on the incubation period and mortality of loggerhead sea turtle (<Emphasis Type="Italic">Caretta</Emphasis><Emphasis Type="Italic">caretta</Emphasis>) pre-emergent hatchlings in Minabe,Japan

Incubation period, hatching success, and emergence percentage in loggerhead (Caretta caretta) nests were quantified during the 1993 and 1995 nesting seasons and following incubation seasons in Minabe, Wakayama, Japan. Sand and nest temperatures were also monitored. Over the seasons, daily mean sand temperature at nest depth fluctuated between 18.0°C and 33.3°C, with a steep increase in the second week of July and a peak in late August. Temperatures inside the nest chambers were a few degrees above those of the surrounding sand at the end of incubation. The incubation period ranged from 46 to 82 days. A significant negative correlation was found between mean sand temperature and incubation period. The relationship conformed to the day-degree concept. There was no significant seasonal trend in hatching success, but many pre-emergent hatchlings were found dead in most of the clutches during the warmest part of the season. Emergence percentage was correlated with mean sand temperature calculated for 4 days before emergence, suggesting that mortality may be due to heat. This heat-related mortality is considered to be a common phenomenon at our study site, because the peak in emergences coincides with the peak in high temperatures. These temperature effects on hatchling mortality must be taken into account in estimates of hatchling sex ratios. Because sand temperatures already exceed the optimal thermal range for incubation, this population is vulnerable to even small temperature increases resulting from global warming.     

Prenatal ultrasound diagnosis of Toriello–Carey syndrome

Toriello–Carey syndrome is a rare malformative complex, described for the first time in 1988, characterized by agenesis of the corpus callosum, facial anomalies, cardiac defects and hypotonia. Relatively few neonatal cases have been reported. We describe here the first prenatal ultrasound diagnosis of the syndrome based on the detection of agenesis of the corpus callosum and spongious cardiomyopathy in a 22-week-old fetus of a couple with positive family history. The first sib of the couple was diagnosed with Toriello–Carey syndrome at 1 year of age, and had, in addition to the typical facial anomalies not detectable by ultrasound, agenesis of the corpus callosum and the same heart lesion (spongious cardiomyopathy). This report demonstrates that prenatal diagnosis of Toriello–Carey syndrome is feasible in the second trimester of pregnancy. Copyright © 2002 John Wiley & Sons, Ltd.     

Preimplantation genetic diagnosis of the fragile X syndrome by use of linked polymorphic markers

Fragile X syndrome is the most common cause of familial mental retardation. The most common mutation is expansion of a triplet (CGG)_n repeat in the 5′ untranslated region of the FMR1 gene on Xq27.3. The expansion is refractory to PCR due to preferential amplification of the smaller allele in heterozygous cells and the high GC content of the repeat and surrounding sequences. Direct detection of the normal parental alleles in preimplantation embryos has been used for preimplantation genetic diagnosis (PGD) of this disorder. However, this approach is only suitable for approximately 63% of couples due to the heterozygosity of the repeat in the normal population. As an alternative we investigated the use of polymorphic markers flanking the mutation to track the normal and premutation carrying maternal chromosomes in preimplantation embryos. Using a panel of 11 polymorphisms, six (CA)_n repeats and five single nucleotide polymorphisms, diagnosis was developed for 90% of referred couples. Multiplex amplification of informative markers was tested in 300 single buccal cells from interested couples with efficiency and allele drop out (ADO) rates ranging from 69% to 96% and 6% to 18%, respectively. Use of this approach is accurate and applicable to a larger number of patients at risk of transmitting fragile X to their offspring. Copyright © 2001 John Wiley & Sons, Ltd.