Parametric study of diethyl phthalate biodegradation

Summary The effects of temperature, dissolved oxygen, and other environmental parameters under both aerobic and anaerobic conditions were investigated using one aerobic and one facultative strain isolated from wastewater treatment plant sludge. Among other results, we found that low dissolved oxygen levels and low temperatures decreased the rate of DEP degradation and the growth rate, and that the facultative strain was much less affected by the lower DO concentrations than the aerobic strain.     

Transport of groundwater-borne nutrients from watersheds and their effects on coastal waters

Anthropogenic activities on coastal watersheds increase nutrient concentrations of groundwater. As groundwater travels downslope it transports these nutrients toward the adjoining coastal water. The resulting nutrient loading rates can be significant because nutrient concentrations in coastal groundwaters may be several orders of magnitude greater than those of receiving coastal waters. Groundwater-borne nutrients are most subject to active biogeochemical transformations as they course through the upper 1 m or so of bottom sediments. There conditions favor anaerobic processes such as denitrification, as well as other mechanisms that either sequester or release nutrients. The relative importance of advective vs. regenerative pathways of nutrient supply may result in widely different rates of release of nutrients from sediments. The relative activity of denitrifiers also may alter the ratio of N to P released to overlying waters, and hence affect which nutrient limits growth of producers. The consequences of nutrient (particularly nitrate) loading include somewhat elevated nutrient concentrations in the watercolumn, increased growth of macroalgae and phytoplankton, reduction of seagrass beds, and reductions of the associated fauna. The decline in animals occurs because of habitat changes and because of the increased frequency of anoxic events prompted by the characteristically high respiration rates found in enriched waters.     

Oxygen consumption and body temperature in yellow-bellied marmot populations from montane-mesic and lowland-xeric environments

Summary Yellow-bellied marmots characteristically live in montane-mesic environments, but in several areas in western North America, this species extended its range into lowland-xeric habitats. Body mass was significantly smaller in the lowland-xeric population from eastern Washington at 393 m than in the montane-mesic population from western Colorado at 2900 m. Oxygen consumption of marmots from montane-mesic and lowland-xeric environments was signiflcantly affected by ambient temperature (T_A) water regimen, population, and a population x water regimen x temperature interaction. Lowland-xeric animals had a higher metabolic rate at low T_As, but a lower metabolic rate at higher T_As than the montane-mesic aminals. Oxygen consumption was lower on a restricted-water regimen than on ad libitum water in both populations. Coefficients relating oxygen consumption to body mass were affected by T_A, water regimen, and population. These intraspecific coefficients are larger than the interspecific coefficients for all mammals. Body temperature (T_B) was affected significantly by T_A, water regimen, and population. T_A body mass, and a population x water regimen interaction significantly affected conductance. Conductance generally was higher in the lowland-xeric than in the montane-mesic marmots. Both populations increased conductance at high T_A, but the lowland-xeric population dissipated a much higher proportion of the heat by evaporative water loss (EWL) than did the montane-mesic population. Metabolic water production exceeded or equaled EWL at 5–20°C. Smaller body size, reduced metabolism at high T_A, and increased EWL at high T_A characterized the lowland-xeric population.Metabolic rates of yellow-bellied marmots were higher than predicted from body size during the reproductive season but decreased to 67% of that predicted from the Kleiber curve by late summer. Marmots minimize thermoregulatory costs by concentrating activity at times when the microclimate is favorable, by tolerating hyperthermia at high T_A in the field, and by having a conductance lower than that predicted from body size.Abbreviations DHC dry-heat conductance - EHL evaporative heat loss - EWL evaporative water loss - HP heat produced - T _A ambient temperature - T _n body temperature - M body mass     

SIMPLE GENETIC BASIS FOR IMPORTANT SOCIAL TRAITS IN THE FIRE ANT SOLENOPSIS INVICTA

Variation in queen phenotype and reproductive role in the fire ant Solenopsis invicta has been shown to have a simple genetic basis in a single introduced population in the United States. The evidence consists of an association between this variation and queen genotype at Pgm-3, a phosphoglucomutase-encoding gene. In the present study, we surveyed Pgm-3 allele and genotype frequencies in diverse populations from the native and introduced ranges of this ant to learn whether this simple genetic basis for reproductive traits is a general feature of the species or a genetic anomaly in introduced ants stemming from a recent bottleneck or the invasion of novel habitats. No egg-laying queens living in polygyne (multiple-queen) nests possessed the homozygous genotype Pgm-3^a/a in any of the study populations, yet nonreproductive females from such nests (workers as well as queens that had not yet initiated oogenesis) possessed this genotype at moderate frequencies. Remarkably, Pgm-3^a/a was the most common genotype among all classes of females, including egg-laying queens, in monogyne (single-queen) nests from all populations studied. Genotype proportions at Pgm-3 in polygyne populations typically departed strongly from the proportions expected under Hardy-Weinberg equilibrium, whereas those in monogyne populations did not. These patterns establish that a single mendelian gene influences queen reproductive role in S. invicta and that this gene uniformly is under strong directional selection in the polygyne social form only. Moreover, the perfect association of Pgm-3 genotype and reproductive role in all populations, combined with the known function of phosphoglucomutase in insect metabolism, suggest that this gene may directly influence queen phenotypes rather than merely serving as a marker for a linked gene that causes the effects.     

Osteoarthritis of the hand in nonhuman primates: A clinical,radiographic, and skeletal survey of Cayo Santiago rhesus macaques

Abstract: We describe the relative prevalence and pattern of distribution of osteoarthritis (OA) in the hands of elderly (>15 years) rhesus macaques using clinical, radiographic, and skeletal examinations. In the clinical study the prevalence of nodes was 72% and 16% in the distal inter-phalangeal joints (DIPJ) and proximal inter-phalangeal joints (PIPJ), respectively, 31% of all monkeys had polyarticular nodes. Radiographic OA was present in 55%, 9.1%, and 0% of the DIPJs, PIPJs, and thumb bases, respectively. Skeletal OA as defined by joint surface eburnation for the DIPJ, PIPJ, and thumb base were 16%, 8%, and 2%, respectively. A similar pattern of hand OA with humans is described except for the thumb base OA. This may be due to the relatively rudimentary manipulative role of the macaque thumb. The finding of polyarticular nodal OA raises the possibility of a common pathogenensis for IPJ OA amongst primates.     

Genomic Analysis of a New Mammalian Distal-less Gene: Dlx7

We have cloned a new Dlx gene (Dlx7) from human and mouse that may represent the mammalian orthologue of the newt geneNvHBox-5.The homeodomains of these genes are highly similar to all other vertebrate Dlx genes, and regions of similarity also exist between mammalian Dlx7 and a subset of vertebrate Dlx genes downstream of the homeodomain. The sequence divergence between human and mouse Dlx7 in these regions is greater than that predicted from comparisons of other vertebrate Dlx genes, however, and there is little sequence similarity upstream of the homeodomain both between these two genes and with other Dlx genes. We present evidence for alternative splicing of mouseDlx7upstream of the homeodomain that may account for some of this divergence. We have mapped humanDLX7distal to the 5′ end of the HOXB cluster at an estimated distance of between 1 and 2 Mb by FISH. Both the human and the mouse Dlx7 are shown to be closely linked to Dlx3 in a convergently transcribed orientation. These mapping results support the possibility that vertebrate distal-less genes have been duplicated in concert with the Hox clusters.