Journal of Developmental Biology

14 pages, 1891 KiB

Open AccessArticle

HP1-Mediated Silencing of the Doublesex1 Gene for Female Determination in the Crustacean Daphnia magna

by Junya Leim, Nikko Adhitama, Quang Dang Nong, Pijar Religia, Yasuhiko Kato and Hajime Watanabe

J. Dev. Biol. 2025, 13(3), 23; https://doi.org/10.3390/jdb13030023 - 3 Jul 2025

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Abstract

The crustacean Daphnia magna produces genetically identical females and males by parthenogenesis. Males are produced in response to environmental cues including crowding and lack of food. For male development, the DM-domain containing transcription factor Doublesex1 (DSX1) is expressed spatiotemporally in male-specific traits and orchestrates male trait formation in both somatic and gonadal tissues. However, it remains unknown how the dsx1 gene is silenced in females to avoid male trait development. Heterochromatin Protein 1 (HP1) plays a crucial role in epigenetic gene silencing during developmental processes. Here we report the identification of four HP1 orthologs in D. magna. None of these orthologs exhibited sexually dimorphic expression, and among them, HP1-1 was most abundantly expressed during embryogenesis. The knock-down of HP1-1 in female embryos led to the derepression of dsx1 in the male-specific traits, resulting in the development of male characteristics, such as the elongation of the first antennae. These results suggest that HP1-1 silences dsx1 for female development while environmental cues unlock this silencing to induce male production. We infer the HP1-dependent formation of a sex-specific chromatin structure on the dsx1 locus is a key process in the environmental sex determination of D. magna. Full article

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25 pages, 5014 KiB

Open AccessArticle

Investigating Psychopharmaceutical Effects on Early Vertebrate Development Using a Zebrafish Model System

by Nathan Zimmerman, Aaron Marta, Carly Baker, Zeljka Korade, Károly Mirnics and Annemarie Shibata

J. Dev. Biol. 2025, 13(3), 22; https://doi.org/10.3390/jdb13030022 - 27 Jun 2025

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Abstract

Cholesterol homeostasis is necessary for normal vertebrate development. The disruption of cholesterol homeostasis can cause abnormal body and nervous system development and lead to dysfunctional behavior and increased mortality. Commonly prescribed psychopharmaceuticals can alter cholesterol synthesis and may disrupt early vertebrate development. A high-throughput vertebrate zebrafish model system was used to test the hypothesis that exposure to psychopharmaceutical medications alters cholesterol biosynthesis and disrupts gene transcription, early whole-body and brain development, and nervous system function, resulting in abnormal behavior. Exposure to cariprazine, aripiprazole, trazodone, and AY9944 increased 7-dehydrocholesterol levels compared to vehicle-treated zebrafish. Significant differences in disease-associated gene expression, brain structure, and functional behaviors were observed in psychopharmaceutical and AY9944-treated zebrafish compared to controls. These data reveal that the high-throughput zebrafish model system can discern psychopharmaceutical effects on cholesterol synthesis, gene transcription, and key features of early vertebrate development that influences behavior. Full article

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14 pages, 1562 KiB

Open AccessArticle

Drosophila Males Differentially Express Small Proteins Regulating Stem Cell Division Frequency in Response to Mating

by Manashree S. Malpe, Leon F. McSwain, Heath M. Aston, Karl A. Kudyba, Chun Ng, Megan P. Wright and Cordula Schulz

J. Dev. Biol. 2025, 13(3), 21; https://doi.org/10.3390/jdb13030021 - 23 Jun 2025

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Abstract

The germline stem cells (GSCs) in the male gonad of Drosophila can increase their division frequency in response to a demand for more sperm caused by repeated mating. However, the molecules and mechanisms regulating and mediating this response have yet to be fully explored. Here, we present the results of a transcriptome analysis comparing expression from the testis tips from non-mated and mated males. An overlapping set of 18 differentially expressed genes (DEGs) from two independent wild-type (wt) strains revealed that the majority of the DEGs encode secreted proteins, which suggests roles for them in cell–cell interactions. Consistent with a role for secretion in regulating GSC divisions, knocking down Signal Recognition Particle (SRP) components within the germline cells using RNA Interference (RNAi), prevented the increase in GSC division frequency in response to mating. The major class of DEGs encodes polypeptides below the size of 250 amino acids, also known as small proteins. Upon reducing germline expression of small proteins, males no longer increased GSC division frequency after repeated mating. We hypothesize that mating induces cellular interactions via small proteins to ensure continued GSC divisions for the production of sperm. Full article

(This article belongs to the Special Issue Drosophila in Developmental Biology—Past, Present and Future)

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J. Dev. Biol., Volume 13, Issue 3 (September 2025) – 3 articles

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