— We investigated the ultrastructure of spermatozoa and some physiological and biochemical parameters of semen in muskellunge Esox musquinongy. Ultrastructure of spermatozoa analyzed with scanning and transmission electron microscopes revealed a spherical head, 1.5 μm in diameter. Unlike the spermatozoa of other teleost fishes, an elongated midpiece with abundant mitochondria was found to be ch...

The aim of our study was to evaluate the effects of chitosan as immune stimulator on some hematological parameters and stress resistance in rainbow trout. Nine hundred rainbow trout (with initial body weight of 25 ± 0.1 g) were obtained from a local farm and acclimated to the laboratory conditions for one week. After that fish were randomly divided into four groups in three replicates. Each gro...

Diclofenac (DCF) is a widely used nonsteroidal anti-inflammatory drug that is regularly detected in surface waters. To support a robust aquatic risk assessment, two early life stage (ELS) tests, compliant with the Organisation for Economic Co-operation and Development (OECD) test guideline 210, were conducted in rainbow trout and in zebrafish. Population relevant endpoints, such as hatching, gr...

Rainbow trout have a limited ability to use dietary carbohydrates efficiently and are considered to be glucose intolerant. Administration of carbohydrates results in persistent hyperglycemia and impairs post-prandial down regulation of gluconeogenesis despite normal insulin secretion. Since gluconeogenic genes are mainly under insulin control, we put forward the hypothesis that the transcriptio...

The importance of rainbow trout (Onchorhynchus mykiss) in Iran aquaculture industry on one hand, and increasing the mortality of this fish due to outbreaks of infectious diseases, on the other hand, indicate the requirement for more profound understanding the rainbow trout immune system and access to laboratory tools for definitive diagnosis of its diseases. One of the most important defense me...

Invasion success may be expected to increase with residence time (i.e., time since first introduction) and secondary releases (i.e., those that follow the original introduction), but this has rarely been tested in natural fish populations. We compared genetic and phenotypic divergence in rainbow trout and brown trout in Chile and the Falkland Islands to test the prediction that adaptive diverge...

Serum and mucosal antibody responses of juvenile rainbow trout, Oncorhynchus mykiss, were characterized by enzyme-linked immunosorbent assay (ELISA) following immunization with various preparations of formalin-killed Flavobacterium psychrophilum cells. The protective nature of these preparations was then determined by immunizing rainbow trout fry and challenging with the bacterium. Juvenile rai...

Humoral antibodies to heat-stable antigens of Renibacterium salmoninarum (Rs) were detected by enzyme-linked immunosorbent assay (ELISA) in rainbow trout Oncorhynchus mykiss and in Atlantic salmon Salmo salar challenged by immersion. A slow antibody response was found: 3% (1/30) was positive 4 wk after immersion and 72% (26/36) was positive after 8 wk. All 30 fish sampled after 4 wk were found ...

A cDNA encoding a new GH family protein expressed in the rainbow trout (Oncorhyncus mykiss) pituitary gland was identified. Because the deduced amino acid sequence of this cDNA shares 56% homology with rainbow trout (rt) somatolactin (rtSL), we named it as rtSL-like protein (rtSLP). Comparison of the amino acid sequences of rtGH, rainbow trout prolactin (rtPRL), and rtSLP revealed that rtSLP sh...

The rainbow trout endocrine system is sensitive to changes in annual day length, which is likely the principal environmental cue controlling its reproductive cycle. This study focuses on the endocrine regulation of vitellogenin (Vg) protein synthesis, which is the major egg yolk precursor in this fish species. We present a model of Vg production in female rainbow trout which incorporates a biol...