In this study the effects of photoperiod and diet, and their interaction, were examined for their effects on growth and body composition in juvenile F344 rats over a 4-week period. On long (16L:8D), relative to short (8L:16D), photoperiod food intake and growth rate were increased, but percentage adiposity remained constant (ca 3-4%). On a high fat diet (HFD), containing 22.8% fat (45% energy a...

Menidia beryllina (Cope) is an annual species that inhabits coastal estuaries along the east coast of the United States from Cape Cod to the Gulf of Mexico. In Rhode Island, USA, its peak spawning time and the duration of the spawning vary among years and estuaries. However, the onset of gonadal maturation is more consistent (early May), suggesting that it may be regulated by more consistent cu...

Earliness of flowering and maturity are important traits in spring Brassica napus canola-whether grown under long- or short-day condition. By use of a spring B. napus mapping population carrying the genome content of B. oleracea and testing this population under 10 to 18 h photoperiod and 18 to 20 0C (day) temperature conditions, we identified a major QTL on the chromosome C1 affecting flowerin...

Seasonal animals adapt their physiology and behaviour in anticipation of climate change to optimise survival of their offspring. Intra-hypothalamic thyroid hormone signalling plays an important role in seasonal responses in mammals and birds. In the F344 rat, photoperiod stimulates profound changes in food intake, body weight and reproductive status. Previous investigations of the F344 rat have...

The experiment was conducted to determine the effects of different photoperiods and darkness on the growth and survival of juvenile Catla catla in the laboratory for 90 days. Fishes were divided into four aquaria (10 fish per aquarium), and subjected to different photoperiod regimes of 8 hours light: 16 hours dark (8L:16D), 16 hours light: 8 hours dark (16L:8D), continuous light (24L:0D) and co...

The effects of season and photoperiod on food storing by black-capped chickadees were examined in two experiments. Chickadees were captured in March (experiment 1) or November (experiment 2), and food storing was tested regularly in the birds’ home cages. In both experiments, two groups were matched for initial level of food storing. The long-day group was then exposed to a summer photoperiod (...

A recently reported circadian rhythm in the spontaneous c-Fos immunoreactivity in the rat suprachiasmatic nucleus (SCN) is expressed mostly in the dorsomedial (dm) SCN, where vasopressinergic cells are located. The aim of the present study is to find out whether day length, i.e., photoperiod, affects the dm-SCN rhythm and, if so, how the rhythm adjusts to a change from a long to a short photope...

to photoperiod. It is widely accepted that the early phase of soybean development is not influenced by photopeTo accurately model the flowering process in soybean, it is essential riod and can therefore be described as a juvenile phase to identify photoperiod-sensitive and photoperiod-insensitive phases (Shanmugasundaram and Tsou, 1978; Hodges and of development. Despite extensive studies, ther...

Melanization reflects not only body color variation but also environmental plasticity. It is a strategy that helps insects adapt to environmental change. Different color morphs may have distinct life history traits, e.g., development time, growth rate, and body weight. The green slender planthopper Saccharosydne procerus (Matsumura) is the main pest of water bamboo (Zizania latifolia). This ins...

Timing of breeding to an optimal season is a requirement for a successful reproductive outcome in seasonally breeding species. Photoperiodic signals are capable of modifying the reproductive behaviour and reproductive systems in several vertebrate species. The cichlid fish Cichlasoma dimerus shows highly organized breeding activities and different social status. The aim of this study is to test...