Biology subjects

Baker, C. C.

Publications and source records attributed to Baker, C. C..

3 recordsLinked to original sources

bioRxiv2024

An RNA binding regulatory cascade controls the switch from proliferation to differentiation in the Drosophila male germ line stem cell lineage

The switch from precursor cell proliferation to onset of differentiation in adult stem cell lineages must be carefully regulated to produce sufficient progeny to maintain and repair tissues, yet prevent overproliferation that may enable oncogenesis. In the Drosophila male germ cell lineage, spermatogonia produced by germ line stem cells undergo a limited number of transit amplifying mitotic divisions before switching to the spermatocyte program that sets up meiosis and eventual spermatid differentiation. The number of transit amplifying divisions is set by accumulation of the bag-of-marbles (Bam) protein to a critical threshold. In bam mutants, spermatogonia proliferate through several extra rounds of mitosis then die without becoming spermatocytes. Here we show that a key role of Bam for the mitosis to differentiation switch is repressing expression of Held Out Wings (how), homolog of mammalian Quaking. Knockdown of how in germ cells was sufficient to allow spermatogonia mutant for bam or its partner benign gonial cell neoplasm (bgcn) to differentiate, while forced expression of nuclear-targeted How protein in spermatogonia wild-type for bam resulted in continued proliferation at the expense of differentiation. Our findings suggest that Bam targets how RNA for degradation by acting as an adapter to recruit the CCR4-NOT deadenylation complex via binding its subunit, Caf40. As How is itself an RNA binding protein with roles in RNA processing, our findings reveal that the switch from proliferation to meiosis and differentiation in the Drosophila male germ line adult stem cell lineage is regulated by a cascade of RNA-binding proteins.

developmental biology↗

bioRxiv2023

A cell-type-specific multi-protein complex regulates expression of Cyclin B protein in Drosophila male meiotic prophase

During meiosis, germ cell and stage-specific components impose additional layers of regulation on the core cell cycle machinery to set up an extended G2 period termed meiotic prophase. In Drosophila males, meiotic prophase lasts 3.5 days, during which spermatocytes turn up expression of over 3000 genes and grow 25-fold in volume. Previous work showed that the core cell cycle regulator Cyclin B (CycB) is subject to translational repression in immature Drosophila spermatocytes, mediated by the RNA-binding protein Rbp4 and its partner Fest. Here we show that another spermatocyte-specific protein, Lut, is required for translational repression of cycB in an 8-hour window just before spermatocytes are fully mature. In males mutant for rbp4 or lut, spermatocytes enter and exit the meiotic divisions 6-8 hours earlier than in wild-type. In addition, we show that spermatocyte-specific isoforms of Syncrip (Syp) are required for expression of CycB protein and normal entry into the meiotic divisions. Both Lut and Syp interact with Fest in an RNA-independent manner. Thus a complex of spermatocyte-specific regulators choreograph the timing of expression of CycB protein during male meiotic prophase. SUMMARY STATEMENTExpression of a conserved cell cycle component, Cyclin B, is regulated by multiple mechanisms in the Drosophila male germline to dictate the correct timing of meiotic division.

developmental biology↗

bioRxiv2020

Large-scale Quantification of Vertebrate Biodiversity in Ailaoshan Nature Reserve from Leech iDNA

1Protected areas are central to meeting biodiversity conservation goals, but measuring their effectiveness is challenging. We address this challenge by using DNA from leech-ingested bloodmeals to estimate vertebrate occupancies across the 677 km2 Ailaoshan reserve in Yunnan, China. 163 park rangers collected 30,468 leeches from 172 patrol areas. We identified 86 vertebrate species, including amphibians, mammals, birds, and squamates. Multi-species occupancy modelling showed that species richness increased with elevation and distance to reserve edge, including the distributions of most of the large mammals (e.g. sambar, black bear, serow, tufted deer). The exceptions were the three domestic mammal species (cows, sheep, goats) and muntjak deer, which were more common at lower elevations. eDNA-estimated vertebrate occupancies are Granular, Repeatable, Auditable, Direct, Efficient, and Simple-to-understand measures that can be used to assess conservation effectiveness and thus to improve the contributions that protected areas make to achieving global biodiversity goals.

ecology↗