Karyotype analysis and sex determination in Australian Brush-turkeys (Alectura lathami)

Sexual differentiation across taxa may be due to genetic sex determination (GSD) and/or temperature sex determination (TSD). In many mammals, males are heterogametic (XY); whereas females are homogametic (XX). In most birds, the opposite is the case with females being heterogametic (ZW) and males the homogametic sex (ZZ). Many reptile spe- cies lack sex chromosomes, and instead, sexual differentiation is influenced by temperature with specific temperatures promoting males or females varying across species possessing this form of sexual differentiation, although TSD has recently been shown to override GSD in Australian central beaded dragons (Pogona vitticeps). There has been speculation that Australian Brush-turkeys (Alectura lathami) exhibit TSD alone and/or in combination with GSD. Thus, we sought to determine if this species possesses sex chromosomes. Blood was collected from one sexually mature female and two sexually mature males residing at Sylvan Heights Bird Park (SHBP) and shipped for karyotype analysis. Karyotype analysis revealed that contrary to speculation, Australian Brush-turkeys possess the classic avian ZW/ZZ sex chromosomes. It remains a possibility that a biased primary sex ratio of Austra- lian Brush-turkeys might be influenced by maternal condition prior to ovulation that result in her laying predominantly Z- or W-bearing eggs and/or sex-biased mortality due to higher sensitivity of one sex in environmental conditions. A better understanding of how maternal and extrinsic factors might differentially modulate ovulation of Z- or W-bearing eggs and hatching of developing chicks possessing ZW or ZZ sex chromosomes could be essential in conservation strategies used to save endangered members of Megapodiidae

Sexual dimorphism in brain transcriptomes of Amami spiny rats (Tokudaia osimensis): a rodent species where males lack the Y chromosome

Abstract Background Brain sexual differentiation is sculpted by precise coordination of steroid hormones during development. Programming of several brain regions in males depends upon aromatase conversion of testosterone to estrogen. However, it is not clear the direct contribution that Y chromosome associated genes, especially sex-determining region Y (Sry), might exert on brain sexual differentiation in therian mammals. Two species of spiny rats: Amami spiny rat (Tokudaia osimensis) and Tokunoshima spiny rat (T. tokunoshimensis) lack a Y chromosome/Sry, and these individuals possess an XO chromosome system in both sexes. Both Tokudaia species are highly endangered. To assess the neural transcriptome profile in male and female Amami spiny rats, RNA was isolated from brain samples of adult male and female spiny rats that had died accidentally and used for RNAseq analyses. Results RNAseq analyses confirmed that several genes and individual transcripts were differentially expressed between males and females. In males, seminal vesicle secretory protein 5 (Svs5) and cytochrome P450 1B1 (Cyp1b1) genes were significantly elevated compared to females, whereas serine (or cysteine) peptidase inhibitor, clade A, member 3 N (Serpina3n) was upregulated in females. Many individual transcripts elevated in males included those encoding for zinc finger proteins, e.g. zinc finger protein X-linked (Zfx). Conclusions This method successfully identified several genes and transcripts that showed expression differences in the brain of adult male and female Amami spiny rat. The functional significance of these findings, especially differential expression of transcripts encoding zinc finger proteins, in this unusual rodent species remains to be determined

Karyotype analysis and sex determination in Australian Brush-turkeys (Alectura lathami)

Sexual differentiation across taxa may be due to genetic sex determination (GSD) and/or temperature sex determination (TSD). In many mammals, males are heterogametic (XY); whereas females are homogametic (XX). In most birds, the opposite is the case with females being heterogametic (ZW) and males the homogametic sex (ZZ). Many reptile spe- cies lack sex chromosomes, and instead, sexual differentiation is influenced by temperature with specific temperatures promoting males or females varying across species possessing this form of sexual differentiation, although TSD has recently been shown to override GSD in Australian central beaded dragons (Pogona vitticeps). There has been speculation that Australian Brush-turkeys (Alectura lathami) exhibit TSD alone and/or in combination with GSD. Thus, we sought to determine if this species possesses sex chromosomes. Blood was collected from one sexually mature female and two sexually mature males residing at Sylvan Heights Bird Park (SHBP) and shipped for karyotype analysis. Karyotype analysis revealed that contrary to speculation, Australian Brush-turkeys possess the classic avian ZW/ZZ sex chromosomes. It remains a possibility that a biased primary sex ratio of Austra- lian Brush-turkeys might be influenced by maternal condition prior to ovulation that result in her laying predominantly Z- or W-bearing eggs and/or sex-biased mortality due to higher sensitivity of one sex in environmental conditions. A better understanding of how maternal and extrinsic factors might differentially modulate ovulation of Z- or W-bearing eggs and hatching of developing chicks possessing ZW or ZZ sex chromosomes could be essential in conservation strategies used to save endangered members of Megapodiidae

Karyotype results for Australian Brush-turkeys.

<p>G-band karyotype images without microchromosomes of A) female <i>A</i>. <i>lathami</i> demonstrating heterogametic ZW sex chromosomes and B) male <i>A</i>. <i>lathami</i> demonstrating homogametic ZZ sex chromosomes, C) G-band sex chromosomes of one female and two male <i>A</i>. <i>lathami</i>, and D) a C-band female metaphase image demonstrating weak to absent C-banding on the Z chromosome and complete C-banding on the W chromosome. For A and B, the numbers of corresponding chromosomes from the <i>G</i>. <i>gallus domesticus</i> karyotype are provided parenthetically.</p

Karyotype results for Australian Brush-turkeys.

<p>G-band karyotype images without microchromosomes of A) female <i>A</i>. <i>lathami</i> demonstrating heterogametic ZW sex chromosomes and B) male <i>A</i>. <i>lathami</i> demonstrating homogametic ZZ sex chromosomes, C) G-band sex chromosomes of one female and two male <i>A</i>. <i>lathami</i>, and D) a C-band female metaphase image demonstrating weak to absent C-banding on the Z chromosome and complete C-banding on the W chromosome. For A and B, the numbers of corresponding chromosomes from the <i>G</i>. <i>gallus domesticus</i> karyotype are provided parenthetically.</p

Mice lacking membrane estrogen receptor 1 are protected from reproductive pathologies resulting from developmental estrogen exposure

Both membrane and nuclear fractions of estrogen receptor 1 (ESR1) mediate 17β-estradiol (E2) actions. Mice expressing nuclear (n)ESR1 but lacking membrane (m)ESR1 (nuclear-only estrogen receptor 1 [NOER] mice) show reduced E2 responsivity and reproductive abnormalities culminating in adult male and female infertility. Using this model, we investigated whether reproductive pathologies caused by the synthetic estrogen diethylstilbestrol (DES) are mitigated by mESR1 ablation. Homozygous and heterozygous wild-type (WT and HET, respectively) and NOER male and female mice were subcutaneously injected with DES (1 mg/kg body weight [BW]) or vehicle daily from postnatal day (PND) 1-5. Uterine histology was assessed in select DES-treated females at PND 5, whereas others were ovariectomized at PND 60 and treated with E2 (10 μg/kg BW) or vehicle 2 weeks later. Neonatal DES exposure resulted in ovary-independent epithelial proliferation in the vagina and uterus of WT but not NOER females. Neonatal DES treatment also induced ovary-independent adult expression of classical E2-induced transcripts (e.g., lactoferrin [Ltf] and enhancer of zeste homolog 2 [Ezh2]) in WT but not NOER mice. At PND 90, DES-treated WT and HET males showed smaller testes and a high incidence of bacterial pyogranulomatous inflammation encompassing the testes, epididymis and occasionally the ductus deferens with spread to lumbar lymph nodes; such changes were largely absent in NOER males. Results indicate that male and female NOER mice are protected from deleterious effects of neonatal DES, and thus mESR1 signaling is required for adult manifestation of DES-induced reproductive pathologies in both sexes

Multigenerational effects of bisphenol A or ethinyl estradiol exposure on F2 California mice (Peromyscus californicus) pup vocalizations.

Rodent pups use vocalizations to communicate with one or both parents in biparental species, such as California mice (Peromyscus californicus). Previous studies have shown California mice developmentally exposed to endocrine disrupting chemicals, bisphenol A (BPA) or ethinyl estradiol (EE), demonstrate later compromised parental behaviors. Reductions in F1 parental behaviors might also be due to decreased emissions of F2 pup vocalizations. Thus, vocalizations of F2 male and female California mice pups born to F1 parents developmentally exposed to BPA, EE, or controls were examined. Postnatal days (PND) 2-4 were considered early postnatal period, PND 7 and 14 were defined as mid-postnatal period, and PND 21 and 28 were classified as late postnatal period. EE pups showed increased latency to emit the first syllable compared to controls. BPA female pups had decreased syllable duration compared to control and EE female pups during the early postnatal period but enhanced responses compared to controls at late postnatal period; whereas, male BPA and EE pups showed greater syllable duration compared to controls during early postnatal period. In mid-postnatal period, F2 BPA and EE pups emitted greater number of phrases than F2 control pups. Results indicate aspects of vocalizations were disrupted in F2 pups born to F1 parents developmentally exposed to BPA or EE, but their responses were not always identical, suggesting BPA might not activate estrogen receptors to the same extent as EE. Changes in vocalization patterns by F2 pups may be due to multigenerational exposure to BPA or EE and/or reduced parental care received

Summary of vocalization parameters affected in F₂ pups multigenerationally exposed to BPA or EE compared to control pups.

<p>Summary of vocalization parameters affected in F₂ pups multigenerationally exposed to BPA or EE compared to control pups.</p

Syllable parameter results in F₂ pups.

<p>A) Latency to first syllable. B) Syllable Power Percent Above 20 KHz. C) Average syllable for female pups. D) Average syllable duration for male pups. Error bars represent SEM.</p