1
|
Parker CG, Craig SE, Histed AR, Lee JS, Ibanez E, Pronitcheva V, Rhodes JS. New cells added to the preoptic area during sex change in the common clownfish Amphiprion ocellaris. Gen Comp Endocrinol 2023; 333:114185. [PMID: 36509136 DOI: 10.1016/j.ygcen.2022.114185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 11/26/2022] [Accepted: 12/07/2022] [Indexed: 12/13/2022]
Abstract
Sex differences in cell number in the preoptic area of the hypothalamus (POA) are documented across all major vertebrate lineages and contribute to differential regulation of the hypothalamic-pituitary-gonad axis and reproductive behavior between the sexes. Sex-changing fishes provide a unique opportunity to study mechanisms underlying sexual differentiation of the POA. In anemonefish (clownfish), which change sex from male to female, females have approximately twice the number of medium-sized cells in the anterior POA compared to males. This sex difference transitions from male-like to female-like during sex change. However, it is not known how this sex difference in POA cell number is established. This study tests the hypothesis that new cell addition plays a role. We initiated adult male-to-female sex change in 30 anemonefish (Amphiprion ocellaris) and administered BrdU to label new cells added to the POA at regular intervals throughout sex change. Sex-changing fish added more new cells to the anterior POA than non-changing fish, supporting the hypothesis. The observed effects could be accounted for by differences in POA volume, but they are also consistent with a steady trickle of new cells being gradually accumulated in the anterior POA before vitellogenic oocytes develop in the gonads. These results provide insight into the unique characteristics of protandrous sex change in anemonefish relative to other modes of sex change, and support the potential for future research in sex-changing fishes to provide a richer understanding of the mechanisms for sexual differentiation of the brain.
Collapse
Affiliation(s)
- Coltan G Parker
- Neuroscience Program, University of Illinois, Urbana-Champaign, 405 N Mathews Ave, Urbana, IL 61801, USA
| | - Sarah E Craig
- Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana-Champaign, 405 N Mathews Ave, Urbana, IL 61801, USA
| | - Abigail R Histed
- Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana-Champaign, 405 N Mathews Ave, Urbana, IL 61801, USA
| | - Joanne S Lee
- Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana-Champaign, 405 N Mathews Ave, Urbana, IL 61801, USA
| | - Emma Ibanez
- Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana-Champaign, 405 N Mathews Ave, Urbana, IL 61801, USA
| | - Veronica Pronitcheva
- Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana-Champaign, 405 N Mathews Ave, Urbana, IL 61801, USA
| | - Justin S Rhodes
- Neuroscience Program, University of Illinois, Urbana-Champaign, 405 N Mathews Ave, Urbana, IL 61801, USA; Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana-Champaign, 405 N Mathews Ave, Urbana, IL 61801, USA; Department of Psychology, University of Illinois, Urbana-Champaign, 603 E Daniel St, Urbana, IL 61801, USA.
| |
Collapse
|
2
|
Kim HJ, Shin SR, Oh HY, Kim JW, Lee JS. Sex of Mussel Mytilus coruscus (Bivalvia: Mytilidae) : Sequential Hermaphroditism. Dev Reprod 2021; 25:55-58. [PMID: 33977175 PMCID: PMC8087255 DOI: 10.12717/dr.2021.25.1.55] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 01/22/2021] [Accepted: 01/29/2021] [Indexed: 11/17/2022]
Abstract
Samples were collected from the subtidal region of Jumunjin on the eastern coast of Korea in July 2020. A total of 338 mussels of shell height (SH) 20.8-149.8 mm were used for sex ratio analysis. The sex ratio (F:M) in the same population of mussel Mytilus coruscus was approximately 1:0.7. The sex ratio according to the class of SH was different. The sex reversal pattern of M. coruscus appears to go from male → female → male → female, and as such is determined to be sequential hermaphrodites.
Collapse
Affiliation(s)
- Hyeon Jin Kim
- Dept. of Aqualife Medicine, Chonnam National University, Yeosu 59626, Korea
| | - So Ryung Shin
- Dept. of Aqualife Medicine, Chonnam National University, Yeosu 59626, Korea
| | - Han Young Oh
- Dept. of Aqualife Medicine, Chonnam National University, Yeosu 59626, Korea
| | - Jae Won Kim
- Dept. of Aquaculture, Gangwon State University, Gangneung 24525, Korea
| | - Jung Sick Lee
- Dept. of Aqualife Medicine, Chonnam National University, Yeosu 59626, Korea
| |
Collapse
|
3
|
Abstract
Sexual fate can no longer be considered an irreversible deterministic process that once established during early embryonic development, plays out unchanged across an organism's life. Rather, it appears to be a dynamic process, with sexual phenotype determined through an ongoing battle for supremacy between antagonistic male and female developmental pathways. That sexual fate is not final and is actively regulated via the suppression or activation of opposing genetic networks creates the potential for flexibility in sexual phenotype in adulthood. Such flexibility is seen in many fish, where sex change is a usual and adaptive part of the life cycle. Many fish are sequential hermaphrodites, beginning life as one sex and changing sometime later to the other. Sequential hermaphrodites include species capable of female-to-male (protogynous), male-to-female (protandrous), or bidirectional (serial) sex change. These natural forms of sex change involve coordinated transformations across multiple biological systems, including behavioral, anatomical, neuroendocrine and molecular axes. Here we review the biological processes underlying this amazing transformation, focusing particularly on the molecular aspects, where new genomic technologies are beginning to help us understand how sex change is initiated and regulated at the molecular level.
Collapse
Affiliation(s)
- Neil J Gemmell
- Department of Anatomy, University of Otago, Dunedin, New Zealand.
| | - Erica V Todd
- Department of Anatomy, University of Otago, Dunedin, New Zealand
| | | | | | - Timothy A Hore
- Department of Anatomy, University of Otago, Dunedin, New Zealand
| |
Collapse
|
4
|
Abstract
Various species of fish living in coral reef communities show sequential hermaphroditism, or sex change. In a typical case, an individual first matures as a female, and later, when it becomes dominant in the mating group, it becomes a male (i.e., protogynous sex change). Many species show only unidirectional changes but some of coral reef fishes exhibit bidirectional sex changes, in which even a dominant male may revert to female when a socially more dominant competitor arrives. However, bidirectional sex change has rarely been observed in natural conditions, even among those species exhibiting it under experimental conditions. Here we explain the rarity of bidirectional sex change by studying dynamics of hormones controlling sex expression. We consider social status factor, SF, which is elevated when the individual becomes more dominant in the mating group. When the SF level is high, the dynamics would culminate with low estradiol expression and high testosterone expression, suggesting a male phenotype. In contrast, when SF level is low, the system converges to an equilibrium with high estradiol expression and low testosterone expression, suggesting a female phenotype. There is a parameter region in which the dynamics exhibit bistability. The model demonstrates hysteresis: as SF increases smoothly, the system undergoes a sudden transition in the levels of sex hormones. The model can explain why species show unidirectional sex change, in that an individual's switch to a new sex is irreversible, even if the individual's social situation returns to the original subdominant status.
Collapse
Affiliation(s)
- Sachi Yamaguchi
- Department of Information Systems Creation, Faculty of Engineering, Kanagawa University, Yokohama 221-8686, Japan, ORCID, 0000-0001-9606-7899.
| | - Yoh Iwasa
- Department of Biology, Faculty of Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan, ORCID, 0000-0003-0691-1852.
| |
Collapse
|