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SYNOPSIS. Since the discovery of the zebra mussel, Dreissena polymorpha, in the Great Lakes in 1988 comparisons have been made with mussel populations in Europe and the former Soviet Union. These comparisons include: Population dynamics, growth and mortality rates, ecological tolerances and requirements, dispersal rates and patterns, and ecological impacts. North American studies, mostly on the zebra mussel and a few on a second introduced species, the quagga mussel, Dreissena bugensis, have revealed some similarities and some differences. To date it appears that North American populations of zebra mussels are similar to European populations in their basic biological characteristics, population growth and mortality...
Categories: Publication; Types: Citation; Tags: American Zoologist
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No abstract available at this time
Categories: Publication; Types: Citation; Tags: American Zoologist
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Some organophosphorus insecticides have been reported to interfere with reproduction and even cause the decline of small mammal populations. The effects of such anticholinesterases on plasma LH concentrations were examined in male mice (Peromyscus leucopus noveboracensis) intubated with water (OW) or acephate (50 and 100 mg/kg) and sacrificed after 4 h. Brain acetylcholinesterase (AChE) activity was inhibited by 45 and 56%, and basal LH levels were reduced by 29 and 25% in mice receiving the 2 doses of acephate. Responsiveness to LHRH did not appear to be affected 4 h after intubation with 100 mg/kg acephate, as 5 ug/kg LHRH ip evoked a comparable rise in plasma LH after 30 min (2.4 and 3.6 fold) in OW-control and...
Categories: Publication; Types: Citation; Tags: American Zoologist
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Some organophosphorus insecticides have been reported to interfere with reproduction and even cause the decline of small mammal populations. The effects of such anticholinesterases on plasma LH concentrations were examined in male mice (Peromyscus leucopus noveboracensis) intubated with water (OW) or acephate (50 and 100 mg/kg) and sacrificed after 4 h. Brain acetylcholinesterase (AChE) activity was inhibited by 45 and 56%, and basal LH levels were reduced by 29 and 25% in mice receiving the 2 doses of acephate. Responsiveness to LHRH did not appear to be affected 4 h after intubation with 100 mg/kg acephate, as 5 ug/kg LHRH ip evoked a comparable rise in plasma LH after 30 min (2.4 and 3.6 fold) in OW-control and...
Categories: Publication; Types: Citation; Tags: American Zoologist
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In the laboratory, juvenile shad under a simulated natural temperature regime (SNT) in freshwater (FW) through the period of fall migration exhibited a 68% decline in plasma [Cl-] and a 3-fold increase in gill Na+K+-ATPase activity.
Categories: Publication; Types: Citation; Tags: American Zoologist
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This laboratory located about 40 miles west of Detroit, near the intersection of highways I-94 and US-23, can be reached by bus, railroad, or via commercial airlines to Detroit Willow Run or Metropolitan airports. Field biological stations are located in Wisconsin at Ashland; in Ohio at Sandusky; and in Michigan at Ludington, Marquette, Millersburg, and Northville.
Categories: Publication; Types: Citation; Tags: American Zoologist
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Diverse field and experimental studies suggest that abnormal sexual and reproductive development in wildlife could be caused by endocrine-like action of pollutants on embryos, and that functional deficits would be evident only later in life, during breeding. We tested these hypotheses in American kestrels (Falco sparverius). Aroclor 1242 is a commercial mixture of PCB congeners shown to be estrogenic in mice and the mixture approximates the environmental exposure of Common terns (Sterna hirundo) where abnormal development of gonads in male tern chicks was seen. Pairs of kestrels were exposed to high and low levels of Aroclor in food resulting in mean egg concentrations of 80.4 and 9.4 ppm respectively. The gonadal...
Categories: Publication; Types: Citation; Tags: American Zoologist
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The reproductive cycle of the zebra mussel (Dreissena polymorpha) is highly variable throughout its range in Europe, Russia, and North America. The environmental factors influencing this variation are poorly understood, but successful reproduction is occurring in areas where it was initially believed that adult zebra mussels could not survive (i.e., southern United States). The differences in mussel reproduction occurring from site-to-site make it difficult to predict timing of specific events, such as the start of larval production, that are important in initiating containment or control procedures. For example, the amount of time required for a fertilized egg to develop into a juvenile mussel can be as short as...
Categories: Publication; Types: Citation; Tags: American Zoologist
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SYNOPSIS. As the primary link between environmental change and physiological response, the neuroendocrinesystem is a critical part of osmoregulatory adaptations. Cortisol has been viewpd as 'the' seawater-adapting hormone in fish and prolactin as 'the' fresh water adapting hormone. Recent evidence indicates that the growth hormone/insulin-like growth factor I axis is also important in seawater adaptation in several teleosts of widely differing evolutionary lineages. In salmonids, growth hormone acts in synergy with cortisol to increase seawater tolerance, at least partly through the upregulation of gill cortisol receptors. Cortisol under some conditions may promote ion uptake and interacts with prolactin during...
Categories: Publication; Types: Citation; Tags: American Zoologist
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Contaminant exposure is an environmental factor often overlooked in ecological studies. Yet exposure to toxicants is likely to be metabolically expensive, and result in a trade-off between energy spent to detoxify an excrete contaminants, and energy allocated to growth or reproduction. To quantify the energetic cost of PCB exposure, we fed mice diets containing 0, 0.1, 10 and 25 ppm PCBs (mg PCBs/kg food). After 6 wks, there were no differences in food intake or body mass related to the level of dietary PCBs. We continued to feed mice the PCB diets for one year, and then measured food intake and resting metabolic rate. After one year, all mice had gained mass, but mice on the 25 ppm diet were significantly heavier...
Categories: Publication; Types: Citation; Tags: American Zoologist