碩士 / 國立海洋大學 / 生物技術研究所 / 84 / Doxin (2,3,7,8-tetrachlorodibenzo-p-dioxin, TCDD) and
relatedpolyhalogenated aryl hydrocarbon compounds (PAHs) have
been listed as the most concered environmental pollutants. The
pathogenities of TCDDand related compounds include
carinogenesis,immune defects and otherdisease. It was speculated
that the cytotoxicities of TCDD is mediatedby nuclear proteins -
dioxin receptor(or aryl hydrocarbon receptor, AhR) and its
heterodimeric partner - Ah receptor nuclear translocator(ARNT).
The molecular basis of activation and function of dioxin
receptoris very similar to that of the steroid hormone
receptors. Both of them are activated by ligand binding in
cytoplasm/nucleus, which in turn bindto upstream response
elements of the target genes in nuclear modulate gene
expression. However, the liganded dioxin receptor binds to the
dioxin - response element (XRE) sequence in a heterodimeric form
which is established by liganded Ah receptor - ARNT association.
The most characterized TCDD-mediated gene activation is
cytochrome P450 1A1 gene (CYP1A1). However, the biological
function of dioxin recepotor and its heterodimeric partner,
ARNT, are still obscure. Recent studies on transgenic murine
model have revealed that dioxin receptor in vital to vertebrate
liver and immune system differentiation. It mammalian embryonic
development. Fishes have very similar xenobiotic - mediated
cytoxicities aswhat mammal does. For instance, fish CYP1A1 gene
activation as well as othercytotoxicities as what cytotoxicities
in fish are propably modulated by cellular dioxin receptor and
its heterodimeric partner, ARNT. In addition, we speculate that
these gene regulator proteins may play similar roles in fish
development as what they does in mammalian development.
Northern hybridization analysis have revealed signigicant
signals from all stages of zebrafish embryonic RNA which were
cross - hybridizedby segments of human AhR and ARNT cDNA.
Interestingly, these genes werehighly expressed during embryonic
development, but none of them could be detected after hatching.
It suggested that both genes are embryonic develop genes which
controls cell differentation in a similar way as whatAhR gene
did in mice embryos. To clone zebrafish AhR and ARNT
genes, we have designed two pairsof degenerate primers which
were corresponding to the N- and C- terminalsequences of PAS
domains in both genes. By using RT-PCR, we have obtained two
specific amplified bands with proper sizes of AhR and ARNT
cDNAfragments, respectively. These amplified DNA segments have
been confirmed as parts of corresponding zebrafish AhR and ARNT
cDNAs. Based on the preliminary sequence alignment, the deduced
amino acid sequences of both genes share about 72%、71% identity
with their corresponding mammalian protein sequences.
| Identifer | oai:union.ndltd.org:TW/084NTOU0108010 |
| Date | January 1996 |
| Creators | Chen, Young-Mao, 陳永茂 |
| Contributors | Hu Chin-Hwa, 胡清華 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 47 |
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