Phenotypic Stability of Sex and Expression of Sex Identification Markers in the Adult Yesso Scallop Mizuhopecten yessoensis throughout the Reproductive Cycle

Abstract

The objective of the present study was to analyze the phenotypic stability of sex after sex differentiation in the Yesso scallop, which is a gonochoristic species that has been described as protandrous. So far, no study has investigated in detail the sexual fate of the scallop after completion of sex differentiation, although bivalve species often show annual sex change. In the present study, we performed a tracking experiment to analyze the phenotypic stability of sex in scallops between one and two years of age. We also conducted molecular marker analyses to describe sex differentiation and gonad development. The results of the tracking experiment revealed that all scallops maintained their initial sex phenotype, as identified in the last reproductive period. Using molecular analyses, we characterized my-dmrt2 and my-foxl2 as sex identification markers for the testis and ovary, respectively. We conclude by proposing that the Yesso scallop is a sex-stable bivalve after its initial sex differentiation and that it maintains a sex-stable maturation system throughout its life. The sex-specific molecular markers identified in this study are useful tools to assess the reproductive status of the Yesso scallop.

Sexual Development of the Hermaphroditic Scallop Argopecten irradians Revealed by Morphological, Endocrine and Molecular Analysis

“…In the present study, we identified single copy FoxL2 and Dmrt1L in A. irradians . As expected, FoxL2 and Dmrt1L showed female- and male-biased expression in the gonad, respectively, similar to the expression patterns of FoxL2 and Dmrt in other bivalves, such as the gonochoristic scallop P. yessoensis ( Li et al, 2018 ; Nagasawa et al, 2019 ), the sequential hermaphrodites C. gigas ( Zhang et al, 2014 ) and P. margaritifera ( Teaniniuraitemoana et al, 2014 , 2015 ). Spatial expression of FoxL2 and Dmrt1L in the ovary and testis revealed that both genes were distributed in follicle cells and germ cells within the follicle, consistent with previous research in the gonochoristic scallop C. farreri ( Liu et al, 2012 ) and P. yessoensis ( Li et al, 2018 ), and the sequential hermaphrodite C. gigas ( Naimi et al, 2009 ).…”

Comparative transcriptome analysis of three gonadal development stages reveals potential genes involved in gametogenesis of the fluted giant clam (Tridacna squamosa)

“…In T. squamosa, sex is more likely to be dominated by the interaction of multiple genes. Next-generation sequencing technology has been utilized to study the genes related to reproduction in various species [18][19][20][21][22][23][24], but no data is currently available on the gonad transcriptome of T. squamosa.…”

The male and female gonad transcriptome of the edible sea urchin, Paracentrotus lividus: identification of sex-related and lipid biosynthesis genes

“…The Dmrt1 gene (DN11344_c0_g1_i5), usually involved in testis development, was also found up-regulated in P. lividus testis. As in many other species, including sea urchins, Dmrt1 is described as playing a major role in sex determination and differentiation in several vertebrate and invertebrate species (Zhang and Zarkower 2017, Nagasawa et al 2019, Sun et al 2019). In accordance with the report of (Sun et al 2019) in M. nudus species, also the Nanos (DN9673_c0_g1_i2) gene in P. lividus is up-regulated in female gonads.…”