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Follistatin-like 1 (Fstl1) peptides play important roles in inhibiting myoblast proliferation and differentiation. Here, we characterized and examined the expression patterns of fstl1a and -b in grass carp ( Ctenopharyngodon idellus ). These genes encode 314 aa and 310 aa peptides, respectively, sharing a sequence identity of 83%. Except for the existence of the follistatin-N-terminal (FOLN) and Kazal-type 2 serine protease inhibitor (Kazal 2) domains, grass carp Fstl1a and -b do not share amino acid sequence similarity with Fst1 and -b. Both fstl1a and -b mRNAs were widely expressed in adult tissues. During embryogenesis, grass carp fstl1a and -b mRNA was detected in the presomitic mesoderm and somites at 12 h post fertilization (hpf). At 24 hpf, fstl1a mRNA was expressed in the hindbrain, somites, notochord and tailbud, while fstl1b mRNA was only detected in the tailbud. At 36 hpf, fstl1a mRNA was detected in the hindbrain and notochord, and fstl1b was also expressed in the notochord. Furthermore, fstl1a and -b were downregulated in brain and liver tissue following injection with 10 or 50 μg hGH, while fstl1b was significantly up-regulated in muscle tissue after 10 μg hGH treatment. Both fstl1a and -b were significantly up-regulated at 2, 4 or 6 days of nutrient restriction, and fstl1a was still highly expressed in the liver and muscle after 3 days of refeeding, as was fstl1b in the brain and muscle. The expression of these genes returned to near control levels following 6 days of refeeding. Our findings suggest that the two fstl s play important but divergent roles in embryonic development and tissue growth regulation in grass carp. [ABSTRACT FROM AUTHOR]

Connective tissue growth factor (CTGF) is a peptide involved in tissue growth and development, and can be regulated by hypoxia stress. This study aimed to isolate and characterize duplicate Ctgf genes in blunt snout bream Megalobrama amblycephala , and determine their expression patterns and response to hypoxia. The blunt snout bream Ctgfa and Ctgfb were found to be highly divergent, sharing a relatively low sequence identity of 57%. During embryogenesis, Ctgfa mRNA expression levels were low, gradually decreased from zygotes to 12 h post-fertilization (hpf), markedly increased from 16 hpf, and then stabilized from 32 to 40 hpf. Ctgfb expression levels were constant but low from zygotes to 20 hpf, then gradually increased from 24 to 40 hpf. Ctgfa mRNA was expressed in the adaxial cells of the somites, floor plate, and tailbud at 24 hpf, and in the notochord and ethmoid plate at 36 hpf, whereas Ctgfb mRNA was weakly expressed in the adaxial cells and floor plate at 24 hpf, and in the notochord at 36 hpf. In adult fish, Ctgfa mRNA was strongly expressed in the kidney, brain, intestine, muscles, and skin, while Ctgfb mRNA was detected in all examined tissues. During hypoxic treatment, the mRNA levels of both Ctgfa and - b were significantly upregulated in the gill and liver, whereas Ctgfa mRNAs in the brain and kidney and Ctgfb mRNAs in the kidney significantly decreased. These results provide new insights into the functional conservation and divergence of Ctgf genes and reveal their responses to hypoxia. [ABSTRACT FROM AUTHOR]