An actomyosin clamp assembled by the Amphiphysin-Rho1-Dia/DAAM-Rok pathway reinforces somatic cell membrane folded around spermatid heads

Emergent dynamics of adult stem cell lineages from single nucleus and single cell RNA-Seq of Drosophila testes

Proper differentiation of sperm from germline stem cells, essential for production of the next generation, requires dramatic changes in gene expression that drive remodeling of almost all cellular components, from chromatin to organelles to cell shape itself. Here, we provide a single nucleus and single cell RNA-seq resource covering all of spermatogenesis in Drosophila starting from in-depth analysis of adult testis single nucleus RNA-seq (snRNA-seq) data from the Fly Cell Atlas (FCA) study. With over 44,000 nuclei and 6000 cells analyzed, the data provide identification of rare cell types, mapping of intermediate steps in differentiation, and the potential to identify new factors impacting fertility or controlling differentiation of germline and supporting somatic cells. We justify assignment of key germline and somatic cell types using combinations of known markers, in situ hybridization, and analysis of extant protein traps. Comparison of single cell and single nucleus datasets proved particularly revealing of dynamic developmental transitions in germline differentiation. To complement the web-based portals for data analysis hosted by the FCA, we provide datasets compatible with commonly used software such as Seurat and Monocle. The foundation provided here will enable communities studying spermatogenesis to interrogate the datasets to identify candidate genes to test for function in vivo.

Expression Analysis in a Dispersal-Fecundity Polyphenism Identifies Growth Regulators and Effectors

Polyphenism allows organisms to respond to varying environmental conditions by adopting alternative collections of morphological traits, often leading to different reproductive strategies. In many insects, polyphenism affecting the development of flight trades dispersal ability for increased fecundity. The soapberry bug Jadera haematoloma (Hemiptera: Rhopalidae) exhibits wing polyphenism in response to juvenile nutritional resources and cohort density. Development of full-length wings and flight-capable thoracic muscles occurs more frequently in cohorts raised under low food density conditions, and these features are correlated to reduced female fecundity. Soapberry bugs represent an example of polyphenic dispersal-fecundity trade-off. Short-wing development is not sex-limited, and morphs can also differ in male fertility. We have previously shown, via a candidate gene approach, that manipulation of insulin signaling can alter the threshold for nutritional response and that changes in the activity of this pathway underlie, at least in part, differences in the polyphenic thresholds in different host-adapted populations of J. haematoloma. We now expand the examination of this system using transcriptome sequencing across a multidimensional matrix of life stage, tissue, sex, food density and host population. We also examine the use of wing and thorax shape as factors modeling gene expression. In addition to insulin signaling, we find that components of the TOR, Hippo, Toll and estrogen-related receptor pathways are differentially expressed in the thorax of polyphenic morphs. The transcription factor Sox14 was one of the few genes differentially expressed in the gonads of morphs, being up-regulated in ovaries. We identify two transcription factors as potential mediators of morph-specific male fertility differences. We also find that bugs respond to nutrient limitation with expression of genes linked to cuticle structure and spermatogenesis. These findings provide a broad perspective from which to view this nutrition-dependent polyphenism.

Time-lapse imaging of Drosophila testis for monitoring actin dynamics and sperm release

Here we describe a simple step-by-step protocol for collecting high-resolution, time-lapse images of intact Drosophila testis ex vivo for a limited period using a confocal microscope, with minimum photo-toxic damage, to monitor spermatid individualization, coiling, and release. The F-actin dynamics during spermatid morphogenesis can be further investigated through laser ablations, Fluorescence-Recovery-After-Photobleaching, and drug treatments, using this protocol.

For complete details on the use and execution of this protocol, please refer to Dubey et al. (2016), Dubey et al. (2019), and Kapoor et al. (2021).

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Protocol for time-lapse imaging of Drosophila testis ex vivo

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The protocol is useful for monitoring spermatid maturation and release

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Also, for high-resolution analysis of subcellular F-actin dynamics