Avian eggshell pigmentation may provide information about a female's physiological condition, in particular her state of oxidative balance. Previously we found that female house wrens ( Vieillot, 1809) with lighter, less-maculated, and redder ground-colored shells were older and produced heavier offspring than females laying darker, browner eggs. The strong pro-oxidant protoporphyrin is responsible for this species' eggshell pigmentation, so differences in pigmentary coloration may be related to eggshell protoporphyrin content and reflect female oxidative balance and condition during egg-formation. Therefore, we tested the assumption that egg-surface coloration is related to the amount of protoporphyrin in the shell matrix. We analyzed digital photographs of eggs to determine maculation coverage as a measure of the overall ground coloration of the egg and its red-, green-, and blue-channel pixel values. Pigments were then extracted from these same eggs and analyzed using high-performance liquid chromatography. There was a strong, positive relationship between eggshell redness and protoporphyrin content of eggshells, but no relationship between percent maculation and protoporphyrin content. Thus, when older, larger females deposit more protoporphyrin in their eggshells, this may reflect a tolerance for high levels of circulating protoporphyrin or an effective mechanism for off-loading protoporphyrin into the eggshell matrix.

Molluscs often possess complex calcified elements in addition to the shell, but how these elements function and relate to other tissues is often poorly understood. Dorid nudibranchs typically possess innumerable calcareous spicules arranged in complex networks. To describe how these spicules interact with muscles and connective tissue, we reconstructed tomographic digital models using serial sections and synchrotron micro-computed tomography. In two species with dramatically different spicule network morphologies, musculature was divided into a dorsal layer of crossed fibres, a ventral layer of branching radial fibres, and scattered dorsoventral fibres in between. These two species differed in the size of their dorsal tubercles, which was reflected in the organization of dorsal musculature, and in the amount and organization of connective tissue. In Bergh, 1905, dense mats of spicules sandwiched a layer of connective tissue with fewer spicules and muscle insertions only onto the ventral spicules. In MacFarland, 1966, thick tracts of spicules are surrounded by a sheath of connective tissue. Muscles surround and insert into the dorsal tubercle spicule layer. Thus, both species appear to use the spicule network for muscle antagonism and transfer of motion, but the different arrangement of elements suggests that they use this skeleton in quite different ways.

In birds, the duration of egg incubation (the time from incubation onset to hatching) can affect multiple components of nest success, but what affects incubation duration? Previous studies suggest that incubation duration is affected by both parental behavior and components of the egg, which have yet to be determined. One egg component that may be related to incubation behavior and the time until hatching is eggshell porosity, which affects the exchange of metabolic gasses and water vapor across the shell and, thus, the speed of embryonic development and incubation duration. We tested whether eggshell porosity was associated with the timing of incubation onset by female House Wrens ( Vieillot, 1809), and whether porosity varied within clutches in a manner that might be associated with incubation periods and hatching patterns (i.e., synchronous vs. asynchronous hatching). Eggshell porosity was unrelated to the onset of maternal incubation and did not differ between early and later-laid eggs within clutches, but differed significantly among females and covaried with egg size. We conclude that producing all eggshells of similar porosity within clutches, while adjusting incubation onset once most or all eggs are laid, provide facultative maternal control over variation in hatching patterns.

cell culture systems from molluscs have significantly contributed to our basic understanding of complex physiological processes occurring within or between tissue-specific cells, yielding information unattainable using intact animal models. cultures of neuronal cells from gastropods show how simplified cell models can inform our understanding of complex networks in intact organisms. Primary cell cultures from marine and freshwater bivalve and gastropod species are used as biomonitors for environmental contaminants, as models for gene transfer technologies, and for studies of innate immunity and neoplastic disease. Despite efforts to isolate proliferative cell lines from molluscs, the snail Say, 1818 embryonic (Bge) cell line is the only existing cell line originating from any molluscan species. Taking an organ systems approach, this review summarizes efforts to establish molluscan cell cultures and describes the varied applications of primary cell cultures in research. Because of the unique status of the Bge cell line, an account is presented of the establishment of this cell line, and of how these cells have contributed to our understanding of snail host-parasite interactions. Finally, we detail the difficulties commonly encountered in efforts to establish cell lines from molluscs and discuss how these difficulties might be overcome.

Phylogenetic relationships within the genus Sigmodon Say and Ord, 1825 were examined using sequence data from multiple gene regions, including exon 1 of the nuclear-encoded interphotoreceptor retinoid binding protein, intron 7 of the nuclear beta-fibrinogen gene, and the mitochondrial cytochrome b gene from 27 individuals representing 11 species of Sigmodon. Nuclear genes were analyzed independently, combined with each other, and combined with the mitochondrial data. Topologies were constructed using parsimony and Bayesian methods, with nodal support provided by bootstrap and posterior probability values. All analyses recovered four independent clades (I-IV), each representing unique species groups: hispidus, fulviventer, peruanus, and alstoni. The analyses from the combined data also provided support for relationships previously proposed within those species groups.

Behavioral management of risk, in which organisms must balance the requirements of obtaining food resources with the risk of predation, has been of considerable interest to ethologists for many years. Although numerous experiments have shown that animals alter their foraging behavior depending on the levels of perceived risk and demand for nutrients, few have considered the role of genetic variation in the trade-off between these variables. We performed a study of four zebrafish (Danio rerio (Hamilton, 1822)) strains to test for genetic variation in foraging behavior and whether this variation affected their response to both aversive stimuli and nutrient restriction. Zebrafish strains differed significantly in their latency to begin foraging from the surface of the water under standard laboratory conditions. Fish fed sooner when nutrients were restricted, although this was only significant in the absence of aversive stimuli. Aversive stimuli caused fish to delay feeding in a strain-specific manner. Strains varied in food intake and specific growth rate, and feeding latency was significantly correlated with food intake. Our results indicate significant genetic variation in foraging behavior and the perception of risk in zebrafish, with a pattern of strain variation consistent with behavioral adaptation to captivity.

Using high-performance liquid chromatography, the quantity of retinol, retinal, and retinyl esters as well as their 3,4-didehydro derivatives were measured in several body compartments and in the remainder of the body of 11 goldfish. Eighty-six percent of these retinoids and 3,4-didehydroretinoids existed as retinyl and 3,4-didehydroretinyl 10% as retinal and 3,4-didehydroretinal, and 4% as retinol and 3,4-didehydroretinol. Most (94%) of these retinoids and 3,4-didehydroretinoids were found in ocular tissues and high ratios of 3,4-didehydroretinoids/retinoids were observed in most tissue extracts. These data suggest that in the goldfish ocular tissues are important locations of retinoid and 3,4-didehydroretinoid metabolism, which favors the formation and (or) storage of 3,4-didehydroretinoids.

Shortly after hatching, Xenopus laevis tadpoles fill their lungs with air. We examined the role played by early lung use in these organisms, since they are able to respire with both their lungs and their gills. We investigated the effect on X. laevis development when the larvae were prevented from inflating their lungs, and whether early lung use influenced the size of the lungs or the tadpole's ability to metamorphose. Tadpoles that were denied access to air had lungs one-half the size of those of controls. This difference in lung size was too large to be explained merely by a stretching of the lung due to inflation. The longer tadpoles were denied access to air, the longer they took to metamorphose, and their probability of completing metamorphosis diminished. One tadpole raise throughout its larval life without access to air successfully metamorphosed but had abnormal, solidified lungs and an enlarged heart. Collectively, these experiments demonstrate that early lung use in tadpoles is important in determining both ultimate lung size and the probability of successfully metamorphosing. Lung use during early larval development in X. laevis is not absolutely necessary for survival through metamorphosis, but its absence severely handicaps growth.

Experimental hypothermia and natural hibernation are two forms of hypometabolism with recognized physiological changes, including depression of endocrine and metabolic functions. To better understand functional changes, helox (i.e., helium and oxygen (80:20) mixtures) and low ambient temperatures have been used to induce hypothermia in hamsters and rats. Both clinical and biological survival, i.e., survival without recovery and survival with recovery from hypothermia, respectively, are related to depth and length of hypothermia. In the rat, body temperatures of 15 degrees C for periods greater than 6-10 h greatly restrict biological survival. The role of glucocorticoids in enhancing thermogenic capacity of rats was assessed using triamcinolone [correction of triamcinalone] acetonide. In the hamster, treatment with cortisone acetate prolonged both clinical and biological survival. Hypothermic hamsters continue utilizing circulating glucose until they become hypoglycemic and die. Hypothermic rats do not utilize glucose and respond with a significant hypoinsulinema. The role of endocrines in the regulation of carbohydrate homeostasis and metabolism differs in hibernation and hypothermia. Glucocorticoids influence the hypothermic response in both species, specifically by prolonging induction of hypothermia in rats and by prolonging survival in hypothermic hamsters.