Hossain, Md. Munir: MicroRNAs in the bovine ovary and placentas derived from in vivo, in vitro and nuclear transfer pregnancies. - Bonn, 2010. - Dissertation, Rheinische Friedrich-Wilhelms-Universität Bonn.
Online-Ausgabe in bonndoc: https://nbn-resolving.org/urn:nbn:de:hbz:5N-23779
urn: https://nbn-resolving.org/urn:nbn:de:hbz:5N-23779,
author = {{Md. Munir Hossain}},
title = {MicroRNAs in the bovine ovary and placentas derived from in vivo, in vitro and nuclear transfer pregnancies},
school = {Rheinische Friedrich-Wilhelms-Universität Bonn},
year = 2010,
month = dec,

volume = 149,
note = {MicroRNAs are the major class of gene regulating molecules playing pivotal roles at post-transcriptional level. Identification and expression profiling are the initial steps to understand their regulation of biological processes. Despite increasing efforts in miRNAs characterization in different species, little is known in the bovine reproductive tissues especially in ovary and placenta. Two subsequent studies were carried out to the expression of miRNAs in bovine ovary and Day-50 placenta derived from different sources of pregnancy. The first study aims to identify and characterize miRNAs in bovine ovary through cloning, expression analysis and target prediction. The constructed miRNA library revealed cloning of 50 known and 24 novel miRNAs. Among these, 38 were new miRNAs which were derived from 43 distinct loci with characteristic secondary structure. Most of the miRNAs were cloned multiple times and thereby reflecting their expression level and potential role in the ovary. Analysis of identified miRNAs in different intra-ovarian structures and other tissues reveals their stage and tissue specific expression patterns. Furthermore, in silico target prediction and Gene Ontology analysis of the targets genes identified several biological processes and pathways underlying the ovarian function. Results of this study suggest the presence of miRNAs in the bovine ovary; thereby elucidate their potential role in regulating diverse mechanisms underlying the ovarian functionality.
The second study aimed to elucidate the difference in expression profile of miRNAs in the placenta at day 50 derived from Somatic cell nuclear transfer (SCNT), in vitro production (IVP) and artificial insemination (AI) pregnancies by quantifying 377 miRNAs. The study reveals a massive deregulation of miRNAs which were poorly reprogrammed and affected as large chromosomal cluster as well as miRNA families in the NT and IVP placenta compared to that of AI. Furthermore, cell specific localization miRNAs in the expanded blastocysts and expression profiling in different developmental stages of embryos and placenta identified that the major deregulation of miRNAs arises at day 50 of NT and IVP pregnancies. This deregulation were found to be less dependent on global DNA methylation, rather aberrant miRNA processing molecules were evidenced. Among them, observed down regulation of AGO2 could be a reason for global down regulation of miRNAs in the NT or IVP placenta. Identified deregulation of miRNAs might associate to the abnormal placentogenesis in NT or IVP pregnancies, which are the results of aberrant genetic and epigenetic modification. Result of this study will help to move one step closer towards improving the efficiency of nuclear transfer pregnancy.
Altogether, the present study has discovered miRNAs in the bovine ovary and elucidated the pattern of expression of miRNAs along with their regulatory mechanism in the placenta derived from pregnancies of various origins.},

url = {https://hdl.handle.net/20.500.11811/4235}

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