عنوان

Comparative studies on insulin-like growth factor-I at the molecular and endocrine levels:

Number

TLpq304441806

.Language of Text, Soundtrack etc

انگلیسی

Title Proper

Comparative studies on insulin-like growth factor-I at the molecular and endocrine levels:

General Material Designation

[Thesis]

First Statement of Responsibility

M. C. McGuinness

Title Proper by Another Author

mRNA structure and gene expression in relation to plasma hormone concentrations

Subsequent Statement of Responsibility

W. L. Bacon

Name of Publisher, Distributor, etc.

The Ohio State University

Date of Publication, Distribution, etc.

1998

Specific Material Designation and Extent of Item

221

Dissertation or thesis details and type of degree

Ph.D.

Body granting the degree

The Ohio State University

Text preceding or following the note

1998

Text of Note

Insulin-like growth factor I (IGF-I) is an important hormonal regulator of embryonic development and postnatal growth. The IGF-I gene expression is complex, with heterogeneity of mRNA structure arising during transcription and splicing of primary RNA transcripts. The chicken has been reported to have a much simpler IGF-I transcript structure than mammalian species, which would distinguish it as the only non-heterogeneous IGF-I cloned thus far. The purpose of the research was to perform comparative studies in two avian species to determine the mRNA structure and gene expression patterns of IGF-I, and to relate these to plasma hormone concentrations. Molecular protocols using alternate methods for RNA cloning were validated for use in reverse transcription-polymerase chain reaction (RT-PCR) cloning of IGF-I from broiler chickens and Japanese quail. Analysis of the 5 regions of chicken and quail IGF-I transcripts showed the presence of two mutually exclusive, alternate leader exons. Therefore, the complexity of IGF-I transcripts was similar among avian and mammalian species. The cDNA sequences of the turkey and Japanese quail IGF-I mature peptide coding region were at least 98% homologous to that of the chicken, and all three species have identical amino acid sequences for IGF-I. Plasma hormones levels and hepatic gene expression during post-hatch growth through sexual maturity were determined in Japanese quail selected for high or low 4 week body weight (BW). Interestingly, the low BW quail were generally hyperpituitary, with significantly higher (p <.05) plasma levels of growth hormone (GH), prolactin, triiodothyronine (T3) and IGF-I. Hepatic expression of GH receptor and plasma GH levels were inversely related. High plasma GH concentrations down-regulated GH receptor expression in low BW birds, and there was a concomitant decrease in GH receptor binding activity in native liver membranes (p <.05). The IGF-I mRNA levels paralleled the relationship seen for plasma IGF-I concentrations among the selected lines. In conclusion, plasma GH and IGF-I levels and IGF-I gene expression were negatively associated with selection for BW. Restriction fragment length polymorphisms in the IGF-I gene were present among the quail lines, indicating gene polymorphisms or alternate IGF-I alleles associated with selection for low or high body weight.

Anatomy & physiology

Animals

Biological sciences

chicken

Japanese quail

turkey

M. C. McGuinness

W. L. Bacon

Electronic name

p

[Thesis]

276903

a

Y