Temporal and spatial variability in estrogenicityhasbeendocumented formany treatedwastewater effluents with the consequences of this variability on the expression of biomarkers of endocrine disruption being largely unknown. Laboratory exposure studies usually utilize constant exposure concentrations which may produce biological effects that differ from those observed in organisms exposed in nat...

To assess the role of the pineal gland in the regulation of ovarian activity, female catfish were exposed to various combinations of photoperiods during the postspawning period of the annual reproductive cycle. Ovarian recrudescence and vitellogenin synthesis were accelerated after pinealectomy in catfish maintained under short photoperiod (9L : 15D) at 25 °C. However, at 25 °C, under long (14L...

Synthesis and release of vitellogenin in the crustacean Isopoda, Porcellio dilatatus, were maximal during premolt. At that time, diurnal variations occurred in the haemolymph protein level and in the synthesis and release of vitellogenin and other proteins in the haemolymph. The pattern of variations was always identical and bimodal: the minima were at dusk and at dawn when the maxima occurred ...

BACKGROUND The vitellogenin receptor (VgR) mediates the uptake of vitellogenin (Vg) from the hemolymph by developing oocytes. RESULTS VgR with the mutational EGF1 domain can bind ligand proteins but cannot be dissociated under acidic conditions. The mutant is lethal in embryos. CONCLUSION Bombyx mori VgR (BmVgR) has an important role in egg formation and embryonic development. SIGNIFICANC...

Nicarbazin (NCZ) is an anticoccidial drug routinely used in the poultry industry that can negatively affect reproduction by reducing egg production, egg weight, and egg hatchability. The molecular mechanisms by which NCZ affects reproduction are unknown. Lipoprotein lipase, vitellogenin, transglutaminase, and calcium are all involved in egg formation and embryogenesis. Therefore, in vitro assay...

In the cockroach Diploptera punctata, vitellogenic basal oocytes stimulate juvenile hormone production by the corpora allata. Experiments with males were designed to determine whether oocytes must grow vitellogenically in order to stimulate juvenile hormone production. Two ovarioles with vitellogenic basal oocytes were implanted into unoperated and sham-operated males that do not produce vitell...

Olive ridley sea turtles (Lepidochelys olivacea) distribute widely throughout Eastern Pacific (EP) waters. During reproduction these animals aggregate near coastal waters where they may be exposed to industrial or agrochemical environmental pollutants that may disrupt the endocrine system of these reptiles. One group of compounds of concern is the persistent organic pollutants (POPs), some of w...