The green frog Rana esculenta is a seasonal breeder. The cyclic changes between almost arrested and highly activated spermatogenesis offer an ideal model to study basic mechanisms of spermatogenesis. In this study, we demonstrated, to our knowledge for the first time, c-kit receptor positive cells in the testis of this amphibian. The presence of c-kit receptor protein was confirmed by western b...

Winter is energetically demanding and stressful; thermoregulatory demands increase when food availability usually decreases. Physiological and behavioral adaptations, including termination of breeding, have evolved among nontropical animals to cope with the energy shortages during winter. Presumably, selection for the mechanisms that permit physiological and behavioral anticipation of seasonal ...

In most parts of the world, environmental conditions vary in a predictable seasonal manner. Thus, seasonal variation in reproductive timing and immune function has emerged in some species to cope with disparate seasonal demands. During the long days of spring and summer when food availability is high and thermoregulatory demands low, Siberian hamsters invest in reproduction, whereas during the ...

Snake fungal disease (SFD) is an emerging threat to snake populations in the United States. Fungal pathogens are often associated with a physiological stress response mediated by the hypothalamo-pituitary-adrenal axis (HPA), and afflicted individuals may incur steep coping costs. The severity of SFD can vary seasonally; however, little is known regarding (1) how SFD infection relates to HPA act...

The white spotted tussock moth, Orgyia thyellina, is a typical insect that exhibits seasonal polyphenisms in morphological, physiological, and behavioral traits, including a life-history tradeoff known as oogenesis-flight syndrome. However, the developmental processes and molecular mechanisms that mediate developmental plasticity, including life-history tradeoff, remain largely unknown. To anal...

Reproductive performance is a key driver of the economics of dairy and beef breeding herds. In the absence of hormonal treatment to induce or stimulate lactation, regular parturition and initiation of lactation are key events directly affecting the average daily milk production of dairy herds, culling decisions and farm gross margins. Thus efficient reproductive management is a critical prerequ...

The two commercially important fruiting cherries in North America are Prunus cerasus L. (sour) and P. avium L. (sweet). Carbon partitioning between individual organs, reproductive and vegetative, is dependent upon photoassimilate supply from photosynthesis and storage carbohydrate, as well as the ability of the translocation system to deliver these resources to sinks (Layne and Flore, 1995). Si...

Gracilinanus microtarsus (J. A. Wagner, 1842), called the Brazilian gracile opossum, is a small didelphid that is 1 of 6 species in the genus Gracilinanus. It is a sexually dimorphic, solitary marsupial that has a highly seasonal reproductive pattern. It inhabits Atlantic rain forests and semideciduous forests interspersed in the highly seasonal cerrado (savanna-like vegetation) in southeastern...

The quantity and quality of propagules, i.e. reproductive output, play a key role in the dynamics of exploited populations, with particular implications for sex-changing fish. �ere, we studied for the first time the effects of maternal traits on the reproductive output of the Mediterranean rainbow wrasse Coris julis, a sequential hermaphroditic fish widely distributed in temperate marine coasta...

Poecilogonous species show variation in developmental mode, with larvae that differ both morphologically and ecologically. The spionid polychaete Pygospio elegans shows variation in developmental mode not only between populations, but also seasonally within populations. We investigated the consequences of this developmental polymorphism on the spatial and seasonal genetic structure of P. elegan...