Temperature and oxygen tension influence the development of muscle cellularity in embryonic rainbow trout

SUMMARY We investigated the effects of the chorion on movement and growth in rainbow trout (Oncorhynchus mykiss) embryos. To test if the chorion restricts movement and growth before hatching, we manually removed the chorion 3–6 days before the natural time of hatching (dechorionated) and compared movement, growth and oxygen consumption in dechorionated embryos and in embryos whose chorions remained intact until the time of hatching(chorionated). Dechorionated embryos exhibited 36 times more movement before hatching compared with intact embryos. By 10 h post-hatch there was no difference in the number of movements between the two groups. At the time of hatching [30 days post-fertilization (d.p.f.)], dechorionated embryos had a significantly greater embryonic body dry mass compared with chorionated embryos, which persisted up to 45 d.p.f. At first feeding (50 d.p.f.) there was no significant difference in embryonic body dry mass between the two groups. Dechorionated embryos had a significantly greater embryonic body protein content after hatching (32, 33 d.p.f.) compared with chorionated embryos. Despite the differences in movement and growth, there were no significant differences in oxygen consumption between chorionated and dechorionated embryos. Furthermore, there was no correlation between the number of movements and oxygen consumption in rainbow trout embryos(chorionated, dechorionated, and hatched). Taken together, the data indicate that rainbow trout embryos have the capacity to be relatively active before hatching, but that the chorion restricts or inhibits movement. Moreover,precocious activity in pre-hatch embryos is correlated with accelerated growth and higher protein content, suggesting that the exercise training effect observed in adult salmonids is also present in early developmental stages.

Section: Growthmentioning

confidence: 78%

Removal of the chorion before hatching results in increased movement and accelerated growth in rainbow trout (Oncorhynchus mykiss)embryos

Ninness

Stevens

Wright

2006

“…Temperature has been shown to influence many aspects of development in teleosts, including muscle cellularity (Stickland et al, 1988;Vieira and Johnston, 1992;Nathanailides et al, 1995;Johnston and McLay, 1997;Matschak et al, 1998;Galloway et al, 1998Galloway et al, , 1999Hall and Johnston, 2003) and the relative timing of myofibrillogenesis (Johnston et al, 1995(Johnston et al, , 1996(Johnston et al, , 1997. There is also a small body of evidence to suggest the timing and extent of MRF gene expression varies with temperature.…”

Section: Introductionmentioning

confidence: 99%

Temperature and the expression of myogenic regulatory factors (MRFs) and myosin heavy chain isoforms during embryogenesis in the common carpCyprinus carpioL.

Cole

Hall

Martin

et al. 2004

“…Temperature is known to have major effects on early muscle development in teleosts, altering the timing of myofibril assembly with respect to somite stage (Atlantic herring, Johnston et al, 1995), as well as the number and size of embryonic muscle fibres in numerous species (Stickland et al, 1988;Vieira and Johnston, 1992;Brooks and Johnston, 1993;Gibson and Johnston, 1995;Hanel et al, 1996;Matschak et al, 1998), including Atlantic cod, Gadus morhua (Galloway et al, 1998;. During ontogeny, embryonic isoforms of the myofibrillar proteins are gradually replaced by larval and adult isoforms, reflecting increases in body sizes and associated changes in swimming behaviour (Martinez et al, 1991;Chanoine et al, 1992;Mascarello et al, 1995).…”

mentioning

confidence: 99%

Temperature and the expression of seven muscle-specific protein genes during embryogenesis in the Atlantic codGadus morhuaL.

Hall

Cole

Johnston

2003

SUMMARYSeven cDNA clones coding for different muscle-specific proteins (MSPs) were isolated from the fast muscle tissue of Atlantic cod Gadus morhua L. In situ hybridization using cRNA probes was used to characterize the temporal and spatial patterns of gene expression with respect to somite stage in embryos incubated at 4°C, 7°C and 10°C. MyoDtranscripts were first observed in the presomitic mesoderm prior to somite formation, and in the lateral compartment of the forming somites. MyoD expression was not observed in the adaxial cells that give rise to the slow muscle layer, and expression was undetectable by in situhybridization in the lateral somitic mesoderm after the 35-somite stage,during development of the final ∼15 somites. RT-PCR analysis, however,confirmed the presence of low levels of the transcript during these later stages. A phylogenetic comparison of the deduced aminoacid sequences of the full-length MyoD cDNA clone and those from other teleosts, and inference from the in situ expression pattern suggested homology with a second paralogue (MyoD2) recently isolated from the gilthead seabream Sparus aurata. Following MyoD expression,α-actin was the first structural gene to be switched on at the 16-somite stage, followed by myosin heavy chain, troponin T, troponin I and muscle creatine kinase. The final mRNA in the series to be expressed was troponin C. All genes were switched on prior to myofibril assembly. The troponin C sequence was unusual in that it showed the greatest sequence identity with the rainbow trout Oncorhynchus mykiss cardiac/slow form, but was expressed in the fast myotomal muscle and not in the heart. In addition, the third TnC calcium binding site showed a lower level of sequence conservation than the rest of the sequence. No differences were seen in the timing of appearance or rate of posterior progression (relative to somite stage) of any MSP transcripts between embryos raised at the different temperatures. It was concluded that myofibrillar genes are activated asynchronously in a distinct temporal order prior to myofibrillar assembly and that this process was highly canalized over the temperature range studied.