Cloning of somatolactin [alpha] and [beta] cDNA subtypes in zebrafish, Danio rerio / by Michael Phillip Shaner.
| Author/creator | Shaner, Michael Phillip author. |
| Other author | Zhu, Yong, degree supervisor. |
| Other author | East Carolina University. Department of Biology. |
| Format | Theses and dissertations |
| Production | 2003. |
| Description | vi, 53 leaves : illustrations ; 28 cm |
| Supplemental Content | Access via ScholarShip |
| Subjects |
| Summary | Somatolactin (SL) is a pituitary hormone that belongs to the growth hormone and prolactin superfamily. Interestingly, all somatolactins share a high sequence identity (amino acid 52-78%), whereas, a somatolactin with low sequence identity (amino acid 35-48%) was reported only in goldfish. Moreover, it is unknown whether these two types of SLs are present in the same species or if the goldfish SL is a novel form only found in cyprinids. We report the cloning of two different zebrafish SL cDNAs. One type is most similar to all other SLs (amino acid identities 46-71%), referred to as ZFSL[alpha]; however, the other type is most similar to goldfish SL (amino acid identity 69.7%), designated zebrafish SL[beta] (ZFSL[beta]). Phylogenetic analyses indicate that these two SLs are paralogous. ZFSL[alpha] groups with all other known SLs, while ZFSL[beta] groups with goldfish SL, catfish, and eel. The full-length ZFSL[alpha] and ZFSL[beta] cDNAs are 823 and 854 bps long, respectively, excluding the poly A-tail. In addition, mature ZFSL[alpha] has 7 conserved cysteines, which is characteristic of all other SL[beta]; however, ZFSL[beta] has 6 conserved cysteine residues. Physiological studies conducted in the last decade suggest that SL might have multiple functions in teleost. All studies have focused on the physiological function of SL[alpha]; therefore, there is no information on the physiological function of SL[beta]. The effects of illumination on ZFSL[beta] mRNA was investigated by measuring changes in mRNA using QRT-PCR during a normal 24 hr cycle. During the day-night cycle there was an increase in ZFSL[beta] mRNA. A 4-fold increase was observed for the dark phase over the fish of the light phase. In addition, changes in ZFSL[beta] mRNA in response to no illumination and enucleation were investigated. The fish exposed to complete darkness had an increase in ZFSL[beta] mRNA, 4-fold compared to fish exposed to the normal light cycle. These results along with previous findings in sciaenids provide further evidence that SL physiology and illumination are closely related. In addition, this is the first report of the cloning of two different SLs in the same species. |
| General note | Presented to the faculty of the Department of Biology. |
| General note | Advisor: Yong Zhu |
| Dissertation note | M.S. East Carolina University 2003 |
| Bibliography note | Includes bibliographical references (leaves 50-53). |
| Genre/form | Academic theses. |
| Genre/form | Academic theses. |
| Genre/form | Thèses et écrits académiques. |
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