With global temperatures projected to surpass the limits of thermal tolerance for many species, evaluating the heritable variation underlying thermal tolerance is critical for understanding the potential for adaptation to climate change. We examined the evolutionary potential of thermal tolerance within a population of chinook salmon (Oncorhynchus tshawytscha) by conducting a full-factorial bre...

Aquatic contaminants, specifically polychlorinated biphenyls (PCBs), a class of persistent organic contaminants, have been associated with sublethal effects on reproduction in fishes. Female brown bullhead (Ameiurus nebulosus) were used to assess variation in reproductive traits across eight populations differing in sediment sum PCB concentrations in the Lower Great Lakes region. Differences in...

Terrestrial eggs have evolved repeatedly in tropical anurans exposing embryos to the new threat of dehydration. Red-eyed treefrogs, Agalychnis callidryas, lay eggs on plants over water. Maternally provided water allows shaded eggs in humid sites to develop to hatching without rainfall, but unshaded eggs and those in less humid sites can die from dehydration. Hatching responses of amphibian eggs...

This paper reports on the fine structure of rat oocytes at stages before ovulation, during maturation, fertilization, and early cleavage. The study includes parallel observations on light and electron microscope preparations with attempted correlations. The follicular cells of the ovarian egg are described as sending long processes through the zona pellucida to the egg surface where they mingle...

Based on evidence from rodent models, it was hypothesized that furan fatty acids found in corn would inhibit reproduction in the laying hen. An isomeric mixture of furan fatty acids [9, (12)-oxy-10,13-dihydroxystearic acid and 10, (13)-oxy-9,12-dihydroxystearic acid] was administered for a period of 3 wk via the diet (1 and 3 ppm) at levels greater than those in corn to 20-wk-old pullets. There...

In order to generate a database for secondary production studies in the São Paulo State (Brazil) reservoirs, the size and dry weight of 13 sooplankton species from Bariri reservoir (middle Tietê River) were determined. Diameter and dry weight of eggs from some cladoceran and copepod species were also determined. Sizes varied from 108.6 microm (Keratella tropica) to 2488.6 microm (females of Arg...

The heterotrophic dinoflagellate Protopemdinium cf. divergens, known as prey for adult copepods, itself feeds on copepod eggs and early naupliar stages. One to several P. cf. divergens can attack an egg or nauplius larger than themselves. The time for an egg to be digested was proportional to the number of P. cf. divergens attacking it. Ingestion rates of P, cf. djvergens on Acartia tonsa eggs ...

Freshwater crabs are an important component of the fauna of limnic environments, and out of the two true freshwater crab families present in the Neotropics, Pseudothelphusidae is the most diverse. Considering the lack of information regarding reproductive features of neotropical freshwater crabs, we studied, for the first time, the fecundity and the presence of juveniles carried by females of t...

Ocean acidification is a growing environmental problem, and there is a need to investigate how the decreasing pH will affect marine organisms. Here we studied the effects of lowered pH on the growth and development of the threespine stickleback (Gasterosteus aculeatus) eggs. Adult fish, collected from the natural environment, were allowed to mate in aquaria and the newly produced eggs were incu...

The objectives of this study were to determine the effects of prolonged exposure to perchlorate on (1) thyroid status and reproductive performance of adult zebrafish (Danio rerio) and (2) F1 embryo survival and early larval development. Using a static-renewal procedure, mixed sex populations of adult zebrafish were exposed to 0, 10, and 100 mg/l nominal concentrations of waterborne perchlorate ...