No abstract

Androgen disrupting chemicals (ADCs) are endocrine disrupting chemicals (EDCs) that mimic or antagonize the effect of physiological androgens. Microarray-based detection of altered gene expression can be used as a biomarker of EDC exposure. Therefore, the purpose of this study was to identify and compare gene expression profiles of the androgen 11-ketotestosterone (11-KT), the antiandrogen flutamide (FLU), and the antiandrogenic fungicide vinclozolin (VIN), on Qurt medaka (Oryzias latipes). Biologically effective concentrations for 11-KT (100 microg/L), VIN (100 microg/L), and FLU (1000 microg/L) determined in range-finding studies were used for exposures. The oligonucleotide microarray included 9379 probes for EDC-affected genes, medaka cDNAs, sequences from the medaka genome project, and the UniGene database. We found that treatment with FLU, VIN, and 11-KT caused significant (false discovery rate = 0.01) differential expression of at least 87, 82, and 578 genes, respectively. Two sets of responsive genes are associated to vertebrate sex differentiation and growth, and 50 genes were useful in discriminating between ADC classes. The discriminating capacity was confirmed by a remarkable similarity of the antiandrogenic expression profiles of VIN and FLU, which were distinct from the androgenic profile of 11-KT. Gene expression profiles characterized in this study allow for reliable screening of ADC activity.

Populations of the Sacramento perch Archoplites interruptus, California's only native centrarchid, are declining and early development of this imperiled species is poorly known. Therefore, the main objective of this study was to describe the early development of Sacramento perch from fertilization to initiation of exogenous feeding. Embryos were obtained in the laboratory by spawning induction via photoperiod‐temperature control or gonadotropin‐releasing hormone analog treatment. Gross morphology and histological analyses were integrated to describe the early development. Cleavage was synchronous until the 64‐cell stage, which allowed us to calculate the duration of one mitotic cycle during early synchronous cleavage (τ0) as 10–16 min at 25.4–25.6°C. A description of histological events from time to morulation, gastrulation, hatch, and exogenous feeding larvae is provided. Yolk sac larvae tended to adhere to the spawning substrate or sediment during the critical organogenesis stages. Larvae swam up and began exogenous feeding within 4 d postfertilization. Primordial germ cells were observed in 10‐d‐old larvae, but sex differentiation occurred after 43 d. External sexual dimorphism was not observed in early life stages.