Journal of Experimental Zoology. Part A, Ecological Genetics and Physiology

Elevation has been proposed as a dominant ecological variable shaping life history traits and subsequently their underlying hormonal mechanisms. In an earlier meta-analysis of tropical birds, elevation was positively related to testosterone levels. Furthermore, parasitism by avian haemosporidians should vary with elevation as environmental conditions affect vector abundance, and while testosterone is needed for breeding, it is hypothesized to be immunosuppressive and thus could exacerbate haemosporidian infection...

The timing of breeding can have significant consequences for adult and offspring fitness, yet our current hypotheses of seasonal timing focus on the parent perspective. When offspring survival is affected by timing of breeding, we expect to see offspring mechanisms to detect and respond to cues of seasonal timing. Avian embryos respond to photoperiod and seasonal cues during development and in this study we evaluate the influence of photoperiod and season on posthatching growth and development in Franklin's gull (Leucophaeus pipixcan)...

Accurate measurements of muscle length changes are essential for understanding the biomechanics of musculoskeletal systems, and can provide insights into muscular work, force, and power. Muscle length has typically been measured in vivo using sonomicrometry, a method that measures distances by sending and receiving sound pulses between piezoelectric crystals. Here, we evaluate an alternative method, fluoromicrometry, which measures muscle length changes over time by tracking the three-dimensional positions of implanted, radio-opaque markers via biplanar videofluoroscopy...

A suppressor of cytokine signaling 2 (SOCS-2) homolog was identified from the red crayfish Procambarus clarkii. Phylogenic analysis showed that P. clarkii SOCS-2 (Pc-SOCS-2) was very similar to that of invertebrates. The sequence contains a central SH2 domain, a conserved SOCS box, and a variable N-terminal domain. Real-time polymerase chain reaction showed that Pc-SOCS-2 mRNA level was higher in muscle and heart than in the other tissues examined. A 40-kDa recombinant protein was successfully expressed and purified from Escherichia coli cells as confirmed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting...

Some amphibian species have developed a breeding strategy in which they deposit their eggs in stable foam nests to protect their eggs and larvae. The frog foam nests are rich in proteins (ranaspumin), especially surfactant proteins, involved in the production of the foam nest. Despite the ecological importance of the foam nests for evolution and species conservation, the biochemical composition, the long-term stability and even the origin of the components are still not completely understood. Recently we showed that Lv-RSN-1, a 23...

Gonadotropin-releasing hormone (GnRH) plays a vital role in the regulation of reproduction through interaction with a specific receptor (the GnRH receptor). In this study, the GnRH receptor gene from the cuttlefish Sepiella japonica (SjGnRHR) was identified and characterized. The cloned full-length SjGnRHR cDNA was 1,468 bp long and contained a 1,029 bp open reading frame encoding 342 amino acid residues, 8 bp of 5' untranslated regions (UTR), and 431 bp of 3' UTR. The putative protein was predicted to have a molecular weight of 38...

Within the taxon Nematoda, many species possess an anhydrobiotic potential similar to other microscopic animals, such as tardigrades and rotifers. This interesting capability enables them to survive conditions even of extreme dehydration. We examined the anhydrobiotic abilities of the two widespread terrestrial nematode species, Plectus parietinus and P. velox, by subjecting adult and juvenile life stages of both species to two different desiccation regimes, one with a short time of adaption (2 hr) and the other with a long time of adaption (48 hr) prior to complete desiccation and recorded the nematodes' recovery after 24 hr of rehydration...

While the use of nanoparticles has dramatically increased in recent years, the ecological consequences are not well known. In particular, little research has been done to investigate the potentially detrimental effects of nanoparticles on amphibians, especially across all life-history stages of salamanders and newts (caudates). To address this dearth in knowledge, we examined the effects of zinc oxide (ZnO) nanoparticles on egg, larval, and adult Rough-skinned Newts (Taricha granulosa). Chronic toxicity was tested on eggs and larvae, and acute toxicity was tested on eggs, larvae, and adults...

Starvation is a primary threat to survival in nature. This study investigated the effects of starvation on animal behavior and neural function using a nematode model. Nematodes exhibit chemotactic responses to various compounds, including diacetyl produced by food bacteria. Locomotion, chemotactic behavior, and olfactory adaptation were measured following chronic starvation. Our results revealed a starvation-dependent reduction in locomotor activity. Chemotaxis response to the odorant diacetyl was attenuated after 2-38 hr of starvation...

Developmental stress can have organizational effects on suites of physiological, morphological, and behavioral characteristics. In lizards, incubation temperature is perhaps the most significant environmental variable affecting embryonic development. Wall lizards (Podarcis muralis) recently introduced by humans from Italy to England experience stressfully cool incubation conditions, which we here show reduce growth and increase the incidence of scale malformations. Using a methylation-sensitive AFLP protocol optimized for vertebrates, we demonstrate that this low incubation temperature also causes hypomethylation of DNA in brain tissue...

Maternal influences are an important contributing factor to offspring survival, development, and behavior. Common environmental pathogens can induce maternal immune responses and affect subsequent development of offspring. There are likely sensitive periods during pregnancy when animals are particularly vulnerable to environmental disruption. Here we characterize the effects of maternal immunization across pregnancy and postpartum on offspring physiology and behavior in Siberian hamsters (Phodopus sungorus)...

Muscle-powered movements are limited by the contractile properties of muscles and are sensitive to temperature changes. Elastic-recoil mechanisms can both increase performance and mitigate the effects of temperature on performance. Here, we compare feeding movements in two species of plethodontid salamanders, Bolitoglossa franklini and Desmognathus quadramaculatus, across a range of body temperatures (5-25°C) to better understand the mechanism of elastically powered, thermally robust movements. Bolitoglossa exhibited ballistic, elastically powered tongue projection with a maximum muscle mass specific power of 4,642 W kg(-1) while Desmognathus demonstrated nonballistic, muscle-powered tongue projection with a maximum power of 359 W kg(-1) ...

Maternally derived corticosterone in the egg and corticosterone produced endogenously by altricial nestling birds play essential roles during development. Although persistently high corticosterone levels can be harmful, moderately elevated levels above baseline can lead to reallocation of resources between growth and maintenance to ensure immediate survival or to enhance the development of fitness-related traits. We tested two hypotheses concerning the fitness consequences of elevated corticosterone during prenatal and postnatal development in altricial house wrens: (1) elevated corticosterone shifts resources away from growth and immune function and (2) elevated corticosterone serves as a signal to allocate resources to fitness-related traits...

The objective of this study was to assess annual redox balance by quantifying activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione S-transferase (GST), as well as measuring lipid peroxidation levels by determination of thiobarbituric acid-reactive substances, in different tissues of male and female crayfish collected from an area little affected by anthropogenic impacts. A total of 37 male and 32 female of Parastacus brasiliensis promatensis were collected over an annual cycle, and gill, muscle, hepatopancreas, and gonad samples were harvested and subjected to the aforementioned analyses via spectrophotometry...

As the smallest living primate, the mouse lemur is a suitable model for reconstructing the locomotor mechanisms by which primate ancestors might have responded to the challenges of an arboreal environment. In this study, we tested the effects of substrate diameter and orientation on quadrupedal gait kinematics in mouse lemurs (Microcebus murinus). Mouse lemurs highly preferred asymmetrical to symmetrical gaits as they moved across a flat board and poles of three diameters (2.5, 1.0, and 0.5 cm), set at horizontal, 30° inclined, and 30° declined orientations...

Maternal stress and care significantly affect offspring's future behavior and physiology. Studies in laboratory rats have shown that maternal stress decreases maternal care and that low rates of certain maternal behaviors cause offspring to develop hyperreactive stress responses. Plurally breeding rodents that practice communal care, such as degus (Octodon degus), may be able to buffer some of these effects since offspring receive care from multiple females. Directly after parturition, 0% (Control group), 50% (Mixed group), or 100% (CORT group) per cage of pair-housed female degus were implanted with 21-day release cortisol pellets...

Sessile marine invertebrates living on hard substrata usually present strategies such as size variations, longer life spans, fragmentation and fusion to occupy and compete for space. Calcareous sponges are usually small and short-lived, and some species are known to undergo frequent fragmentation and fusion events. However, whether fusion occurs only between genetically identical individuals remains unclear. We investigated the occurrence of chimaeras in the calcareous sponge Clathrina aurea by following the dynamics of fragmentation and fusion of 66 individuals in the field for up to 18 months and determined size variations and the life span of each individual...

Seasonal acclimatization permits organisms to maintain function in the face of environmental change. Tadpoles of the green frog (Lithobates clamitans) overwinter as tadpoles in much of their range. Because they are active in winter, we hypothesized that green frog tadpoles would display acclimatization of metabolic and locomotor function. We collected tadpoles in Sewanee, Tennessee (35.2°N) in winter and summer. Tadpoles collected during each season were tested at both winter (8°C) and summer (26°C) temperatures...

The timekeeping mechanisms that operate at the core of circadian clocks (oscillators) are based on interacting molecular feedback loops consisting of clock and clock-associated genes. However, there is a lack of comprehensive studies on the expression of clock genes (particularly those forming its core) in single crustacean species at the mRNA and protein levels, and these studies could serve as a basis for constructing a model of the crustacean molecular oscillator. Studies on Daphnia pulex are well suited to fill this gap because this species is the only representative crustacean whose genome has been sequenced...

Endotherms maintain high and constant body temperatures through the production and maintenance of metabolic heat. Defining the evolutionary history of these thermal adaptations and the selective factors responsible for the evolution of endothermy despite its high metabolic costs have been elusive and controversial topics in evolutionary biology. In this sense, several models have been proposed to explain the evolution of endothermy. Among them, the parental care model explains the increase in resting metabolic rate (RMR) by the action of natural selection favoring parental care...