ADAMTS9 IS NECESSARY FOR THE SEXUAL DEVELOPMENT OF FEMALE ZEBRAFISH

ECU Author/Contributor (non-ECU co-authors, if there are any, appear on document)

Nichole J Carter (Creator)

Institution

East Carolina University (ECU )

Web Site: http://www.ecu.edu/lib/

Abstract: The ovary is a unique organ as it must cyclically alter its structure to accommodate the growth , development , and release of oocytes. The processes of oogenesis and ovulation requires structural modifications made to the extracellular matrix (ECM) enabling cell migration , differentiation , and survival. ADAMTS9 (A disintegrin and metalloprotease with thrombospondin type-1 motif 9) is a metalloprotease that digests ECM proteoglycans , versican and aggrecan. Adamts9 was found to be expressed highly in preovulatory follicular cells of zebrafish , humans and macaques. Increase of adamts9 expression was also found in preovulatory follicular cells treated with progestin and/or gonadotropin. PGRKO zebrafish have significantly reduced expression of adamts9 , reduced adamts9 expression in response to progestin treatments in preovulatory follicles and has an anovulatory phenotype- indicating adamts9 may play a key role during zebrafish ovulation. Aberrant migration of the primordial germ cells has been reported in the knockouts of Adamts9 ortholog in C. elegans and Drosophila. Adamts9 was found to be expressed widely in all tissue types and relatively high in the mouse genital tubercle. Unfortunately , Adamts9 knockout mice die before gonad differentiation. So , the function of ADAMTS9 in the vertebrate ovary has not been determined. To identify the function of Adamts9 in zebrafish ovaries we generated Adamts9 global knockout (adamts9-/-) zebrafish using CRISPR/Cas9 and characterized the effects of knockouts. From 1149 fish generated from crossing of adamts9+/- , we found significantly fewer adatms9-/- fish (4%) than predicted by mendelian ratios (25%). The surviving mutant fish had a significant male bias (87%). The females that were found (2%) had small , ovaries with few stage III and IV oocytes compared to WT counterparts of a similar age and body length. No female-like fish were observed to release eggs and no ovulated ova were observed in histological sections. Astoundingly , the remaining mutants (11%) did not appear to have normal testis or ovaries , but instead had an empty , ovarian membrane-bound compartment that filled the abdominal cavity. On the periphery of these ovary-like compartments , seminiferous tubules and various spermatocytes including normal developed sperms were observed. To our knowledge , this is the first report of an established Adamts9 knockout vertebrate line and the first description of how sex determination and gonadal structure are affected , highlighting the importance of Adamts9 function in the development of gonads and the value of zebrafish as a model organism.

Additional Information

Publication

Thesis

Language: English

Date: 2018

Keywords

ovulation, metalloprotease, CRISPR

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