A Novel igf3 Gene in Common Carp (Cyprinus carpio): Evidence for Its Role in Regulating Gonadal Development.

Since the insulin-like growth factor 3 (igf3) gene was recently discovered in fish ovary, its function in the gonads has received much attention. In this study, we isolated two igf3 subtypes from common carp (Cyprinus carpio), which comprised full-length cDNA of 707 and 1153 nucleotides encoding 205 and 198 amino acids (aa), respectively. The Igf3 aa sequence had the highest gene homology of 72% with the corresponding sequence in zebrafish (Danio rerio). Phylogenetic tree construction revealed that the C. carpio igf3 gene was first clustered with D. rerio and then with other teleost species. Igf3 mRNA was widely expressed, with expression being highest in the gonads and blood. In the gonad development stage, igf3a mRNA expression was highest in the maturity and recession stage of the ovary, and decline phase of the testis, while igf3b was highest in the recession and fully mature periods of the ovaries and testes, respectively. Western blotting of testis protein samples showed two bands of approximately 21 kDa and 34 kDa corresponding to the calculated molecular mass of the two Igf3 subtypes; no signal was detected in the ovary. The Igf3 protein was localized in the ovary granulosa cells and testis spermatogonium and spermatids. 17ß-Ethinylestradiol treatment increased both ovary and testis igf3 mRNA expression. These findings suggest that Igf3 may play an important role in C. carpio gonadal development.

Patterns of nucleotide diversity at the regions encompassing the Drosophila insulin-like peptide (dilp) genes: demography vs. positive selection in Drosophila melanogaster.

In Drosophila, the insulin-signaling pathway controls some life history traits, such as fertility and lifespan, and it is considered to be the main metabolic pathway involved in establishing adult body size. Several observations concerning variation in body size in the Drosophila genus are suggestive of its adaptive character. Genes encoding proteins in this pathway are, therefore, good candidates to have experienced adaptive changes and to reveal the footprint of positive selection. The Drosophila insulin-like peptides (DILPs) are the ligands that trigger the insulin-signaling cascade. In Drosophila melanogaster, there are several peptides that are structurally similar to the single mammalian insulin peptide. The footprint of recent adaptive changes on nucleotide variation can be unveiled through the analysis of polymorphism and divergence. With this aim, we have surveyed nucleotide sequence variation at the dilp1-7 genes in a natural population of D. melanogaster. The comparison of polymorphism in D. melanogaster and divergence from D. simulans at different functional classes of the dilp genes provided no evidence of adaptive protein evolution after the split of the D. melanogaster and D. simulans lineages. However, our survey of polymorphism at the dilp gene regions of D. melanogaster has provided some evidence for the action of positive selection at or near these genes. The regions encompassing the dilp1-4 genes and the dilp6 gene stand out as likely affected by recent adaptive events.

The IGF1 small dog haplotype is derived from Middle Eastern grey wolves.

BACKGROUND: A selective sweep containing the insulin-like growth factor 1 (IGF1) gene is associated with size variation in domestic dogs. Intron 2 of IGF1 contains a SINE element and single nucleotide polymorphism (SNP) found in all small dog breeds that is almost entirely absent from large breeds. In this study, we surveyed a large sample of grey wolf populations to better understand the ancestral pattern of variation at IGF1 with a particular focus on the distribution of the small dog haplotype and its relationship to the origin of the dog. RESULTS: We present DNA sequence data that confirms the absence of the derived small SNP allele in the intron 2 region of IGF1 in a large sample of grey wolves and further establishes the absence of a small dog associated SINE element in all wild canids and most large dog breeds. Grey wolf haplotypes from the Middle East have higher nucleotide diversity suggesting an origin there. Additionally, PCA and phylogenetic analyses suggests a closer kinship of the small domestic dog IGF1 haplotype with those from Middle Eastern grey wolves. CONCLUSIONS: The absence of both the SINE element and SNP allele in grey wolves suggests that the mutation for small body size post-dates the domestication of dogs. However, because all small dogs possess these diagnostic mutations, the mutations likely arose early in the history of domestic dogs. Our results show that the small dog haplotype is closely related to those in Middle Eastern wolves and is consistent with an ancient origin of the small dog haplotype there. Thus, in concordance with past archeological studies, our molecular analysis is consistent with the early evolution of small size in dogs from the Middle East.See associated opinion by Driscoll and Macdonald: http://jbiol.com/content/9/2/10.

Expression, mitogenic activity and regulation by growth hormone of growth hormone/insulin-like growth factor in Branchiostoma belcheri.

The growth hormone (GH)/insulin-like growth factor (IGF) axis is unique to all the vertebrate species but its evolutionary origin is ill-defined. We therefore cloned a cDNA encoding Branchiostoma belcheri IGF (BbIGF). BbIGF was expressed in a tissue-specific manner, with the most abundant expression in the hepatic caecum, the putative liver precursor. The recombinant BbIGF expressed in vitro showed mitogenic activity capable of stimulating cell proliferation in the flounder gill, a characteristic of vertebrate IGF. Quantitative real-time polymerase chain reaction demonstrated that the recombinant rat GH was able to induce a significant up-regulation of BbIGF expression in the hepatic caecum. Moreover, Western blotting revealed the presence of a molecule similar to rat GH receptor in the hepatic caecum. These results suggest that BbIGF expression is inducible by exogenous mammalian GH, suggesting the presence of a GH/IGF axis in B. belcheri. The relationship between BbIFG expression and the origin of the vertebrate liver is discussed.

Insulin-like growth factors (IGFs) and IGF binding proteins in active Crohn's disease treated with omega-3 or omega-6 fatty acids and corticosteroids.

OBJECTIVE: Catabolism and growth impairment are well-known complications of inflammatory bowel disease (IBD). This may be caused by the disease activity itself and/or the medical treatment, and both may lead to changes in the growth hormone (GH)/insulin-like growth factor I (IGF-I) axis. The aim of the present study was to examine the effects of enteral nutrition, Impact Powder, as adjuvant therapy to corticosteroid treatment on changes in the GH/IGF-I axis in patients with Crohn's disease (CD). MATERIAL AND METHODS: The patients were randomized to 3-IP (omega-3-fatty acid (FA), 3 g/day) or 6-IP (omega-6-FA, 9 g/day). Changes in total IGF-I (tIGF-I) and total IGF-II (tIGF-II), free IGF-I (fIGF-I), IGF binding proteins (IGFBP-1 and IGFBP-3), IGFBP-3 protease activity and insulin levels were examined in 31 patients with active CD (CDAI: 186-603) during treatment with prednisolone (40 mg for 1 week) and tapering the dose by 5 mg/week. Clinical and biochemical markers of inflammation were studied at day 0, and after 5 and 9 weeks. RESULTS: There were no differences at baseline between the two groups. During the treatment period, tIGF-I, fIGF-I and IGFBP-3 increased significantly in both groups compared to baseline (p<0.05) without differences between the groups. Insulin and IGFBP-1 showed no significant changes throughout the treatment period. CONCLUSIONS: There was no difference between 3-IP and 6-IP as adjuvant enteral nutrition on the GH/IGF-I axis. The changes observed in the GH/IGF-I axis are in line with previously published studies and may be explained by corticosteroid treatment; however, we cannot exclude an additional effect of omega3-/omega6 FA as adjuvant enteral nutrition.

Distinct expression pattern of insulin-like growth factor family in rodent taste buds.

The insulin-like growth factor (IGF) system is an important regulator of growth and differentiation in a variety of tissues. In the present study, the expression of IGF family members in the taste buds of mice and rats was examined. By reverse transcriptase polymerase chain reaction (RT-PCR) analysis, mRNA of IGF-I and -II, IGF-I receptor (IGF-IR), insulin receptor (insulin R), and IGF-binding protein (IGFBP)-2, -3, -4, -5, and -6 was detected in the taste bud-containing epithelium of the circumvallate papillae of mice. As suggested by the study using degenerate PCR (McLaughlin [2000] J. Neurosci. 20:5679-5688), IGF-IR was expressed in most of the taste bud cells of adult mice, as found by immunohistochemistry, and in those of postnatal day (P) 6 mice by in situ hybridization. Insulin R, which has strong homology to IGF-IR, was also detected in most of the taste bud cells of mice by immunohistochemistry and in situ hybridization. IGF-I immunoreactivity was detected in a few taste bud cells and in the epithelium surrounding taste buds. Northern blot analysis revealed that the amount of IGF-I mRNA in taste bud-containing epithelium was very low compared with that in liver. IGF-II immunoreactivity was weakly detected in mouse taste buds and the surrounding epithelium. In the rat tissue, a subset of the taste bud cells was positive for IGF-II. Among the six IGFBPs, IGFBP-2, -5, and -6 were detected in the mouse taste buds: IGFBP-2 and -5 immunoreactivity was seen in the majority of the taste bud cells, whereas IGFBP-6 immunoreactivity was found in the nerve fibers innervating the taste buds. In situ hybridization study also revealed that IGFBP-2 and -5 mRNA was synthesized in the taste buds of P6 mice and that the expression of these mRNAs overlapped in von Ebner's glands. These data reveal that IGF-I and -II might be produced in taste bud cells and (or) surrounding lingual epithelium and act through IGF-IR and insulin R locally in a paracrine and autocrine manner. The activity of these IGFs may be modulated through their interaction with IGFBP-2, -5, and 6.

Efeito da pectina e celulose nos níveis de somatomedina C e síntese de proteoglicano no músculo e cartilagem de ratos / Effect of pectin and celullose on the levels of somatomedin C and synthesis of proteoglycan in a muscle and rats cartilages

A suplementacao de 15 por ciento de pectina na dieta causa diminuicao do crescimento, porem o mecanismo desse processo nao está ainda estabelecido. Concentracao plasmática de somatomedina C ou insulin-like growth factor (IGF-I) e síntese de proteoglicano no músculo e na cartilagen foram comparados em ratos em crescimento alimentados com dietas de 8,5 por ciento de proteína e teores de 7,5 e 15 por ciento de celulose e pectina, respectivamente. No experimento 1 (G1-G6) foi usada celulosa como fonte de fibra e no experimento 2 (G7-G11) pectina. Uma acentuada reducao no peso, ingestao de alimento e crescimento do músculo e do osso foram observado no grupo alimentado com pectina 15 por ciento. A concentracao plasmática de somatomedina C correlacionou com a síntese de proteína e de proteoglicano no osso no grupo alimentado com pectina 15 por ciento. No entanto, nos grupos alimentados com celulosa a maioria dos parâmetro analisados nao foram alterados, com excecao dos grupos alimentados com a mistura de arroz e feijao (grupos G5 e G6). Nosso estudo sugere que a suplementacao de pectina na dieta prejudicou o crescimento devido a menor ingestao de alimento, reduzida resposta anabólica com menor síntese de proteína e de proteoglicano refletindo uma menor acao e secrecao da somatomedina C

[Insulin-like growth factors and gonadal regulation in fish]. / Facteurs de croissance de type insulinique et régulation gonadique chez les poissons.

Recent data showing the occurrence of IGF in fish, mainly teleostean fish, and their biological activity in gonads are reviewed. IGF-I does occur in all vertebrates and first evidence of IGF-II occurrence in fish has been reported. IGF-I is expressed in the testis and the ovary, and receptors for the peptide have been demonstrated in both gonads. Besides, IGF-I seems implied in spermatogonial proliferation and in oocyte maturation. Both germinal cells and somatic cells could be responsive to IGF-I stimulation.