Carl S. Hacker

Bioaccumulation of Lead and Cadmium in the Royal Tern and Sandwich Tern

Lead and cadmium concentrations were measured in eggs and tissues of downy young, prefledgling, and adult Royal and Sandwich Terns collected from Galveston Bay, Texas. These species do not differ significantly in the amount of heavy metals they accumulate; however, they differed from other species of the same trophic level from Galveston Bay in degree and pattern of temporal accumulations of these metals. Lead levels were lower in terns, but cadmium levels in adult terns were higher than those of other species. The pre-fledglings of other species at this trophic level have lead and cadmium concentrations which are similar to those found in adults. In contrast, the concentrations of the metals in adult terns are markedly higher than those found in prefledgling terns. This suggests that accumulation of metals continues as the birds age.

Environmentally acquired lead, cadmium, and manganese in the cattle egret, Bubulcus ibis, and the laughing gull, Larus atricilla.

The concentrations of lead, cadmium, and manganese in the tissues of cattle egrets (Bubulcus ibis) and laughing gulls (Larus atricilla) gathered from the Galveston Bay region of Texas were compared, to determine if different patterns of accumulation exist. Their levels in these species were within the range reported for other bird species. Lead levels in bone were comparable, but gulls had more lead in brain, kidney and liver tissues than the egrets, which suggested a higher rate of accumulation or exposure. Due to their high abundance and comparable positions in the estuarine and terrestrial food webs, it is suggested thatBubulcus ibis andLarus atricilla may serve as convenient biological indicators to monitor potentially toxic substances in these ecosystems.

Bioaccumulation of lead and cadmium in the Louisiana heron (Hydranassa tricolor) and the cattle egret (Bubulcus ibis)

Lead and cadmium concentrations in the tissues and stomach contents of several age classes of Louisiana herons (Hydranassa tricolor) and cattle egrets (Bubulcus ibis) from the Galveston Bay region of Texas were measured, and levels of exposure and the rates of accumulation by these species were compared. Statistical analyses showed no differences in the rates and patterns of accumulation of these metals between these species; however, tissue and age class were both significant variables. Lead concentrations were highest in the bone of adult birds, while cadmium was highest in the adult kidney. Although these birds feed in different habitats, analyses of metal content in their food items showed similar rates of exposure. We note an important distinction between biomagnification and ontogenetic accumulation in studies which seek to estimate the importance of trophic position on risk of exposure to heavy metals.

Effects of salinity, temperature, and cadmium on cadmium-binding protein in the grass shrimp,Palaemonetes pugio

The combined effects of salinity, temperature, and cadmium on the accumulation of cadmium-binding protein (CdBP) were studied in the grass shrimp,Palaemonetes pugio. In 96-hr bioassays, shrimp were exposed either to zero or to one of three concentrations of cadmium, under one of six different salinity and temperature regimes. Cadmium-binding protein concentrations were quantified in survivors from the 24 exposure groups. Salinity and temperature did not affect survivorship unless the shrimp were also exposed to cadmium.P. pugio produced a 10,000-dalton metallothionein-like CdBP when exposed to at least 0.1 mg Cd2+/L for 96 hr. Accumulation of CdBP was elevated when either the level of cadmium or temperature was increased or salinity was decreased. Grass shrimp surviving the salinitytemperature-cadmium conditions associated with highest mortality exhibited the highest levels of CdBP. Thus, CdBP accumulation is not only related to cadmium exposure, but can be synergistically affected by environmental factors as well. The utility of metal-binding proteins to monitor physiological stress in estuarine biota that inhabit environments polluted with heavy metals is discussed.

DEMOGRAPHIC AND SPATIAL ANALYSIS OF WEST NILE VIRUS AND ST. LOUIS ENCEPHALITIS IN HOUSTON, TEXAS

ABSTRACT This descriptive prevalence study describes the relationships between mosquito density and the presence of arboviruses (in mosquitoes and humans) with various socioeconomic and environmental factors present near the time of the arbovirus outbreak in Harris County, Texas, in 2002. This study suggests that mosquito density increased if the trap was located in an area with a large number of containers that may inadvertently retain rainwater (P = 0.056). When considering only virus-positive mosquitoes, significant relationships were observed if the trap was located near waste materials (P < 0.001) or near containers that may inadvertently retain rainwater (P = 0.037). Furthermore, the presence of arbovirus activity (in mosquitoes or humans) in a geographic area tended to be associated with the socioeconomic status of the local community. Although the results of the socioeconomic comparisons were not significant, they were suggestive, demonstrating an interesting trend. Compared with communities where virus activity was not observed, the socioeconomic status of the arbovirus-positive community was consistently lower. Specifically, results showed that the populations residing in virus-positive census tracts attained less education, earned less income per household, and were more likely to be below the poverty level. In addition, this study found that virus-positive mosquitoes were randomly distributed throughout the study area, whereas severe human infection cases were clustered. Based on the results of this study, we conclude that the health outcome of a local community as it relates to West Nile virus and St. Louis encephalitis is dependent on many factors, including the socioeconomic and environmental characteristics of the community.

Laws pertaining to healthcare-associated infections: a review of 3 legal requirements.

We reviewed US state and territorial healthcare-associated infection (HAI) laws, specifically addressing 3 legal requirements: data submission, reporting of data to the public, and inclusion of facility identifiers in public reports. The majority of US states and territories have HAI laws. The 3 studied legal provisions are all commonly included in state HAI laws in varying forms; however, only a minority of states and territories specifically mandate all 3 legal requirements. The laws of the remaining states vary considerably.

Biochemical genetics of the culex pipiens complex—II. Hexokinase

1. 1. Three isoenzymes of the enzyme hexokinase (EC 2.7.1.1) are observed in adult mosquitos. The tissue distribution and ontogeny of these isoenzymes has been examined. 2. 2. A genetic polymorphism at the hexokinase locus has been observed in the C. pipiens complex. 3. 3. The hexokinase isozymes which are produced by the alleles found in northern and southern populations of C. pipiens have been partially purified and their properties compared. 4. 4. The proposal that selection by environmental temperature is responsible for the observed distribution of these alleles is discussed.

Biochemical genetics of the Culex pipiens complex. I. 6-phosphogluconate dehydrogenase

Abstract 1. 1. A genetic polymorphism at the 6-phosphogluconate dehydrogenase locus has been observed in C. pipiens complex. 2. 2. The 6-phosphogluconate dehydrogenase isoenzymes found in northern and southern populations of C. pipiens have been partially purified and their properties compared. 3. 3. The two isoenzymes differ significantly in thermal stability. 4. 4. The thermal stability differences between the two isoenzymes are consistent with environmental selection by temperature.

Genetic polymorphism of isocitrate dehydrogenase in the Culex pipiens complex

Isocitrate dehydrogenase (IDH) constitutes a group of enzymes which catalyze the reversible oxidation-decarboxylation of L-isocitrate yielding 7ketogtutarate and require a divalent metal ion for activity. It was first demonstrated by Henderson (1965, 1968) that NADP-dependent ID H (E.C. 1.1.1.42) exists in two isozymatic forms in most mammals, the supernatant and mitochondrial forms. Multiple IDH loci have also been widely reported to be a ubiquitous phenomenon in many fish species (Siciliano and Wright, 1973). McGinnis et al. (1956) demonstrated that IDH-NADP exists in both the supernatant and mitochondrial fractions of the blowfly, Phormia regina. On the other hand, Fox et al. (1972) reported that both the supernatant and mitochondrial IDH-NADP are electrophoretically identical isozymes in Drosophila rnelanogaster, although only 16~ of the IDH-NADP activity is detected in mitochondrial fractions. Fox (1971) also determined that the three IDH-NADP electrophoretic patterns seen in D. melanogaster are due to two alleles of a single structural locus. The present report deals with the genetics of the IDH-NADP isozymes in the Culex pipiens complex.