OBJECTIVE To estimate the prevalence of low cardiorespiratory fitness and its association with excess body fat, considering the sexual maturation and economic level in female adolescents. METHODS Cross-sectional, epidemiological study of 1,223 adolescents (10-17 years) from the public school system of Cascavel, PR, Brazil, in 2006. We analyzed the self-assessed sexual maturation level (prepub...

In the mound-building mouse, Mus spicilegus, which is found from Central to Eastern Europe, reproduction is seasonal and limited to spring and summer. In autumn, the mice build voluminous mounds composed of vegetable matter covered with earth, where juvenile animals (autumnal individuals) over-winter in groups without reproducing. Autumnal animals delay reproduction until the next spring when t...

Bisphenol A (BPA) is a chemical used extensively to manufacture commonly used plastics and epoxy resin liners for food and beverage cans. BPA, with properties similar to diethylstilbestrol, has been shown to exert endocrine-disrupting effects and result in behavioral changes, altered growth, and early secondary sexual maturation. In 2008, legislation was introduced at the state and federal leve...

The distribution of corner (putative ultraviolet-sensitive) cones in the retina of Atlantic salmon was examined from the small juvenile (parr) stage to the adult stage (approaching sexual maturation). Small parr weighing approximately 5 g lacked corner cones everywhere except, mainly, near the dorsal periphery. Large fish ( approximately 5 kg) approaching sexual maturation showed corner cones i...

Male nematodes secrete pheromones that accelerate the somatic senescence of potential mates. A new study shows that this harm most likely is an unintended by-product of the males' aim to speed up sexual maturation and delay reproductive senescence of future partners.

Eyespots on the body of many animals have long been assumed to confer protection against predators, but empirical evidence has recently demonstrated that this may not always be the case and suggested that such markings may also serve other purposes. Clearly, this raises the unresolved question of what functions do these markings have and do they contribute to an individual's evolutionary fitnes...

Age- and size-related life-history traits of anuran amphibians are thought to vary systematically with latitude and altitude. Because the available data base is strongly biased towards temperate-zone species, we provide new estimates on eight afrotropical Reed Frog species. A meta-analysis of the demographic traits in 44 tropical anuran species aims to test for the predicted clinal variation an...

Spring-hatched broiler breeders housed in non-lightproof facilities are frequently maintained on long daylengths to prevent precocity, but controlled-feeding and delayed dissipation of photorefractoriness retard sexual maturation. Trials were conducted to determine the appropriate growth for birds maintained on 14-h photoperiods, and to compare responses with naturally increasing and decreasing...

This study examines the effect of FSH, testosterone and estradiol on testicular LH receptors and in vitro testicular responsiveness to LH in immature rats under various conditions. FSH treatment of 15-day-old immature rats significantly increased the number of LH receptors but did not alter testicular responsiveness. FSH treatment of hypophysectomized immature rats increased the number of LH re...

Progenesis is defined as the retention of ancestral juvenile characters by adult stages of descendants due to an acceleration of the sexual maturation and thus is often regarded as a fast evolutionary process. Several small, meiofaunal polychaetes, such as Dinophilidae, some "Dorvilleidae" (for example, Parapodrilus), and Protodrilida, exhibit morphological simplicity in that they lack features...