Screening pentachlorophenol degradation ability by environmental fungal strains belonging to the phyla Ascomycota and Zygomycota

Pentachlorophenol (PCP) bioremediation by the fungal strains amongst the cork-colonising community has not yet been analysed. In this paper, the co- and direct metabolism of PCP by each of the 17 fungal species selected from this community were studied. Using hierarchical data analysis, the isolates were ranked by their PCP bioremediation potential. Fifteen isolates were able to degrade PCP under co-metabolic conditions, and surprisingly Chrysonilia sitophila, Trichoderma longibrachiatum, Mucor plumbeus, Penicillium janczewskii and P. glandicola were able to directly metabolise PCP, leading to its complete depletion from media. PCP degradation intermediates are preliminarily discussed. Data emphasise the significance of these fungi to have an interesting potential to be used in PCP bioremediation processes.     

Assignment of uroporphyrinogen decarboxylase (UROD) to the pter----p21 region of human chromosome 1

The assignment of the human gene for uroporphyrinogen decarboxylase (UROD) to chromosome 1 is confirmed and further localized to the pter----p21 region through the use of human-mouse somatic cell hybrids. Human and mouse UROD were separated by electrophoresis and identified with antibodies to the human enzyme after electrophoretic transfer to nitrocellulose membranes.     

Vital rates of two small populations of brown bears in Canada and range‐wide relationship between population size and trend

Identifying mechanisms of population change is fundamental for conserving small and declining populations and determining effective management strategies. Few studies, however, have measured the demographic components of population change for small populations of mammals (<50 individuals). We estimated vital rates and trends in two adjacent but genetically distinct, threatened brown bear (Ursus arctos) populations in British Columbia, Canada, following the cessation of hunting. One population had approximately 45 resident bears but had some genetic and geographic connectivity to neighboring populations, while the other population had <25 individuals and was isolated. We estimated population‐specific vital rates by monitoring survival and reproduction of telemetered female bears and their dependent offspring from 2005 to 2018. In the larger, connected population, independent female survival was 1.00 (95% CI: 0.96–1.00) and the survival of cubs in their first year was 0.85 (95% CI: 0.62–0.95). In the smaller, isolated population, independent female survival was 0.81 (95% CI: 0.64–0.93) and first‐year cub survival was 0.33 (95% CI: 0.11–0.67). Reproductive rates did not differ between populations. The large differences in age‐specific survival estimates resulted in a projected population increase in the larger population (λ = 1.09; 95% CI: 1.04–1.13) and population decrease in the smaller population (λ = 0.84; 95% CI: 0.72–0.95). Low female survival in the smaller population was the result of both continued human‐caused mortality and an unusually high rate of natural mortality. Low cub survival may have been due to inbreeding and the loss of genetic diversity common in small populations, or to limited resources. In a systematic literature review, we compared our population trend estimates with those reported for other small populations (<300 individuals) of brown bears. Results suggest that once brown bear populations become small and isolated, populations rarely increase and, even with intensive management, recovery remains challenging.     

Acute altitude exposure and altered acid-base states. I. Effects on the exercise ventilation and blood lactate responses

This study examined the influence of acute altitude (AL) exposure alone or in combination with metabolic acid-base manipulations on the exercise ventilatory and blood lactate responses. Four subjects performed a 4 min, 30 W incremental test to exhaustion at ground level (GL) and a 4 min, 20 W incremental test during three acute exposures to a simulated altitude of 4200 m; (i) normal (NAL), (ii) following 0.2 g.kg-1 ingestion of sodium bicarbonate (BAL), and (iii) following 0.5 g.day-1 ingestion of acetazolamide for 2 days prior to exposure (AAL). VE.VO2-1 increased progressively throughout the incremental tests at AL and the minimum value was not related to a change in the blood lactate response. In contrast, the VE.VCO2-1 decreased initially to reach a minimum value at the same power output for each altitude trial and was related to a lactate threshold defined by a log-log transformation (r = 0.78). This transformation of the blood lactate data was not influenced by the altered acid-base states. The relative exercise intensity corresponding to both a delta lactate of 1 mM and an absolute lactate of 4 mM was significantly increased during the AAL (79.9 +/- 12.9 and 93.9 +/- 13.7% VO2max, respectively) compared with NAL (59.1 +/- 5.5 and 78.0 +/- 5.8% VO2max, respectively). These data suggest that strong relationships exist between the ventilatory and blood lactate response during AL exposure and altered acid-base states. Further, it is concluded that, unless the acid-base status is known, the use of an absolute or delta lactate value to compare submaximal exercise should be interpreted with caution.     

The influence of site-specificity of single amino acid substitutions on electrophoretic separation of yeast iso-1-cytochromec

Summary This study dealt with the ability of non-denaturing gel electrophoresis to separate iso-1-cytochromec with single amino acid replacements isolated from revertants of variouscyc1 nonsense mutants of the yeastSaccharomyces cerevisiae. A total of 28 different iso-1-cytochromesc with single amino acid substitutions of one of seven amino acids at six positions were examined on nondenaturing polyacrylamide gels at pH 4.8. Each of these iso-1-cytochromesc exhibited 1 of 16 distinct electrophoretic mobilities. We could distinguish the majority of iso-1-cytochromesc, even those having the same replacement at different sites and those having different replacements that resulted in the same net charge. These results provide confirmation of the importance of site-specific effects on the electrophoretic mobility, and presumably other properties, of proteins differing in sequence by as little as one amino acid. They demonstrate that nondenaturing electrophoresis is able to separate the majority of, but not all, proteins differing by single amino acids.     

The sensitivity of isoelectric focusing and electrophoresis in the detection of sequence differences in proteins

Fourteen myoglobins of known sequence were examined by isoelectric focusing with and without urea. The 14 sequences formed six distinct mobility classes on gels without urea and three classes on those with urea. For these proteins, isoelectric focusing provides no advantage over single, nonequilibrium, nondenaturing gels in the total number of distinguishable mobility classes. Only major charge differences, resulting from the changes in the total numbers of acidic and basic amino acids, can be detected on gels with urea, indicating that denaturation by urea alters proteins so that small differences in ionization are eliminated.We thank the Department of Biology, University of Utah, for financial support.     

A model of evaporation from the skin while wearing protective clothing

 A simple model was developed to describe the transport of water vapour from subjects working in hot environments while wearing chemical-protective clothing. The goal of the modelling was to obtain a better estimate of evaporative cooling of the subjects, as it was hypothesised that calculations of evaporative heat loss based on changes in dressed weight over-estimate the actual benefit experienced by the subjects. The model employed measured values of vapour pressure within the clothing ensemble to estimate the skin vapour pressure. The resistance of the clothing ensemble to water vapour transport was calculated from measurements of the physical properties of the materials in conjunction with estimates of the resistance of air layers between the clothing layers. The model predicts mean evaporation rates from the skin that are approximately 60% of those calculated from measured changes in dressed weight. Error analysis failed to account for the magnitude of this difference and possible explanations for the difference are advanced. A brief examination of the effect of wicking suggests that some of the difference results from a reduction of the resistance of the garment to water vapour due to wicking of liquid sweat through fabric layers. Received: 4 June 1997 / Accepted: 21 October 1997     

Acclimation or stress symptom? An integrated study of intraspecific variation in the clonal plant Aechmea bromeliifolia,a widespread CAM tank‐bromeliad

The clonal tank-bromeliad Aechmea bromeliifolia (Rudge) Baker was found in four different habitats in a restinga (vegetation mosaic on sandy coastal plains), of south-eastern Brazil. These habitats (swamp forest, dry forest, dry shrubland and herbaceous marsh) lie within a few hundred metres of each other along a gradient extending inland from the coast, and differ markedly in terms of light and flood regime. We compared ramet morphology, leaf anatomy and physiology, and population parameters to examine the amplitude of trait variation of this widespread species in the studied restinga. This integrated approach allowed us to examine which variation conferred acclimation and which was merely a stress symptom. A . bromeliifolia showed site-specific differences in abundance, distribution, rosette size and shape, leaf anatomical arrangement and photochemical efficiency (potential quantum yield; F _v/ F _m) during the day. Most of the variation found seemed to be related to the interaction of light and flooding. The lowest number and size of ramets at the exposed, dry shrubland was matched by a marked leaf photoinhibition, which suggested poor acclimation to local levels of light intensity and limited water supply. In the other habitats, the morpho-physiological parameters measured suggested adequate foraging behaviour and site acclimation.  © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society, 2002, 140 , 391-401.