Dataset Information

Identifying Sex of Neonate Turtles with Temperature-dependent Sex Determination via Small Blood Samples.

ABSTRACT: Temperature-dependent sex determination, present in most turtle species, is a mechanism that uses temperature to direct the sex of the embryo. The rapid increase of global temperatures highlights the need for a clear assessment of how sex ratios of organisms with TSD are affected. In turtles with TSD, quantifying primary sex ratios is challenging because they lack external dimorphism and heteromorphic sex chromosomes. Here we describe a new technique used to identify sex in neonate turtles of two TSD species, a freshwater turtle (Trachemys scripta) and a marine turtle (Caretta caretta) via analysis of small blood samples. We used an immunoassay approach to test samples for the presence of several proteins known to play an important role in sex differentiation. Our results show that Anti-Mullerian Hormone (AMH) can be reliably detected in blood samples from neonate male turtles but not females and can be used as a sex-specific marker. Verification of sex via histology or laparoscopy revealed that this method was 100% reliable for identifying sex in both T. scripta and C. caretta 1-2 day-old hatchlings and 90% reliable for identifying sex in 83-177 day-old (120-160?g) loggerhead juveniles. The method described here is minimally invasive, and for the first time, greatly enhances our ability to measure neonate turtle sex ratios at population levels across nesting sites worldwide, a crucial step in assessing the impact of climate change on imperiled turtle species.

SUBMITTER: Tezak B

PROVIDER: S-EPMC7081227 | biostudies-literature | 2020 Mar

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Identifying Sex of Neonate Turtles with Temperature-dependent Sex Determination via Small Blood Samples.

Tezak Boris B Sifuentes-Romero Itzel I Milton Sarah S Wyneken Jeanette J

Scientific reports 20200319 1

Temperature-dependent sex determination, present in most turtle species, is a mechanism that uses temperature to direct the sex of the embryo. The rapid increase of global temperatures highlights the need for a clear assessment of how sex ratios of organisms with TSD are affected. In turtles with TSD, quantifying primary sex ratios is challenging because they lack external dimorphism and heteromorphic sex chromosomes. Here we describe a new technique used to identify sex in neonate turtles of tw ...[more]

PMID: 32193464

Similar Datasets

Project description:Vertebrate sexual fate is decided primarily by the individual's genotype (GSD), by the environmental temperature during development (TSD), or both. Turtles exhibit TSD and GSD, making them ideal to study the evolution of sex determination. Here we analyze temperature-specific gonadal transcriptomes (RNA-sequencing validated by qPCR) of painted turtles (Chrysemys picta TSD) before and during the thermosensitive period, and at equivalent stages in soft-shell turtles (Apalone spinifera-GSD), to test whether TSD's and GSD's transcriptional circuitry is identical but deployed differently between mechanisms. Our data show that most elements of the mammalian urogenital network are active during turtle gonadogenesis, but their transcription is generally more thermoresponsive in TSD than GSD, and concordant with their sex-specific function in mammals [e.g., upregulation of Amh, Ar, Esr1, Fog2, Gata4, Igf1r, Insr, and Lhx9 at male-producing temperature, and of β-catenin, Foxl2, Aromatase (Cyp19a1), Fst, Nf-kb, Crabp2 at female-producing temperature in Chrysemys]. Notably, antagonistic elements in gonadogenesis (e.g., β-catenin and Insr) were thermosensitive only in TSD early-embryos. Cirbp showed warm-temperature upregulation in both turtles disputing its purported key TSD role. Genes that may convert thermal inputs into sex-specific development (e.g., signaling and hormonal pathways, RNA-binding and heat-shock) were differentially regulated. Jak-Stat, Nf-κB, retinoic-acid, Wnt, and Mapk-signaling (not Akt and Ras-signaling) potentially mediate TSD thermosensitivity. Numerous species-specific ncRNAs (including Xist) were differentially-expressed, mostly upregulated at colder temperatures, as were unannotated loci that constitute novel TSD candidates. Cirbp showed warm-temperature upregulation in both turtles. Consistent transcription between turtles and alligator revealed putatively-critical reptilian TSD elements for male (Sf1, Amh, Amhr2) and female (Crabp2 and Hspb1) gonadogenesis. In conclusion, while preliminary, our data helps illuminate the regulation and evolution of vertebrate sex determination, and contribute genomic resources to guide further research into this fundamental biological process.

Project description:In this study, we examined whether a homolog of the master sex-determining gene amhy of Odontesthes hatcheri is present and plays any role in testis determination of pejerrey O. bonariensis, a species otherwise known for its strong temperature-dependent sex determination (TSD). Screening of wild and laboratory-reared pejerrey for amhy revealed a high, although not complete linkage with phenotypic sex. The sex ratio in an amhy+/-/amhy-/- full sibling progeny reared during the thermolabile period of sex determination at an intermediate temperature of 25°C was 68.7% male:31.3% female; all amhy+/- fish developed as males whereas about 2/3 and 1/3 of the amhy-/- were female and male, respectively. Expression analyses revealed that amhy transcription began during embryo stage and decreased by the end of sex determination period. The autosomal amha was present in all individuals regardless of amhy genotype; its expression increased significantly from the end of the same period in the gonads of all amhy+/- but only in part of the amhy-/- animals. After histological gonadal differentiation, all gonads of amhy-/- animals with amha ISH signals were testes and those without it were ovaries. These results suggest that amhy is important for testicular differentiation in pejerrey, at least at intermediate temperatures. Thus, we hypothesize that amhy+/- animals differentiate as males by expression of either amhy alone or amhy and amha together whereas the amhy-/- probably rely solely on amha expression. These findings represent the first clear genomic evidence that genotypic and environmental sex determinants can coexist in species with marked TSD such as the pejerrey. The finding of amhy will make possible to monitor wild pejerrey populations for mismatches between genotypic and phenotypic sex and may prove instrumental for field studies addressing the effects of endocrine disruptors or abnormal temperatures on reproduction and the ecological relevance of TSD for this species.

Dataset Information

Identifying Sex of Neonate Turtles with Temperature-dependent Sex Determination via Small Blood Samples.

Publications

Identifying Sex of Neonate Turtles with Temperature-dependent Sex Determination via Small Blood Samples.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets