Use of somatic cell nuclear transfer to study meiosis in female cattle carrying a sex-dependent fertility-impairing X-chromosome abnormality.
Animal models have played an important part in establishing our knowledge base on reproduction, development, and the occurrence and impact of chromosome abnormalities. Translocations involving the X chromosome and an autosome are unique in that they elicit sex-dependent infertility, with male carriers rendered sterile by synaptic anomalies during meiosis, whereas female carriers conceive but repeatedly abort. Until now the limited access to relevant fetal oocytes has precluded direct study of meiotic events in female carriers. Because somatic cell nuclear transfer (SCNT) circumvents meiotic problems associated with fertility disturbances in translocation carriers, we used SCNT to generate embryos, fetuses, and calves from a cell line derived from a deceased subfertile X-autosome translocation carrier cow to study the meiotic configurations in carrier oocytes. Data from 33 replicates involving 2470 oocyte-donor-cell complexes were assessed for blastocyst development and of these, 42 blastocysts were transferred to 21 recipients. Fourteen pregnancies were detected on day 35 of gestation. One of these was sacrificed for ovary retrieval on day 94 and three went to term. Features of oocytes from the fetal ovary and from the newborn ovaries were examined. Of the pachytene spreads analyzed, 16%, 82%, and 1.5% exhibited quadrivalent, trivalent/univalent, and bivalent/univalent/univalent structures, respectively, whereas among the diakinesis/metaphase I spreads, 16% ring, 75% chain, and 8.3% bivalent/bivalent configurations were noted, suggesting that the low fertility among female carriers may be related to synaptic errors in a predominant proportion of oocytes. Our results indicate that fibroblasts carrying the X-autosome translocation can be used for SCNT to produce embryos, fetuses, and newborn clones to study such basic aspects of development as meiosis and to generate carriers that cannot easily be reproduced by conventional breeding.
Rho
Gyu-Jin
GJ
Department of Biomedical Science, University of Guelph, Guelph, Ontario, Canada.
Coppola
Gianfranco
G
Sosnowski
Jaroslaw
J
Kasimanickam
Ramanathan
R
Johnson
Walter H
WH
Semple
Esther
E
Mastromonaco
Gabriela F
GF
Betts
Dean H
DH
Koch
Thomas G
TG
Weese
Scott
S
Hewson
Joanne
J
Hayes
Michael Anthony
MA
Kenney
Daniel G
DG
Basrur
Parvathi K
PK
King
William Allan
WA
D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000235:genetics; D005260:Female; D040181:Genetic Diseases, X-Linked / Q000235:genetics; D007247:Infertility, Female / Q000235:genetics / Q000662:veterinary; D008540:Meiosis; D008954:Models, Biological; D053652:Nuclear Transfer Techniques; D011247:Pregnancy; D012729:Sex Chromosome Aberrations / Q000662:veterinary