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Neurodegenerative diseases are devastating conditions characterized by progressive cognitive decline with few available treatments. Neurodegeneration can be quantified in vertebrate and invertebrate models of disease by analysis of vacuolation - the formation of empty spaces within brain tissue. Previous approaches for quantifying this phenotype have required time-consuming methods such as manual counting and measuring of vacuole dimensions, which can be subjective. Here we describe VacQuant, a novel application that can be paired with existing machine learning software to automatically measure the area of vacuolation in brain tissue. Using Drosophila brain sections from tauopathy model flies, a well-described model of dementia-related neurodegeneration, we quantified a significant increase in brain vacuolation at several timepoints in adult flies with the aid of VacQuant. When compared with quantification by five blinded volunteers, the machine learning method positively correlated with their group average, confirming its accuracy and functionality. This automated method developed with VacQuant removes human bias and measurement variation, providing a consistent threshold for all brain sections and experiments. This automated pipeline will be particularly useful for high-throughput screening for genetic modifiers or therapeutic compounds in animal models of neurodegeneration.

Drosophila melanogaster, the common fruit fly, has been instrumental to our understanding of evolution, genetics and disease. There are benefits to studying these flies in the wild, including assessment of their naturally occurring microbiota. To facilitate efforts to catch wild D. melanogaster, we designed two fly traps and evaluated several candidate attractants. The first trap utilized a stable food substrate that can be used to catch live flies to establish new lab colonies. The second trap was designed to be reusable and easy to ship to enable the collection of flies over time from diverse locations. We evaluated several chemical attractants derived from banana and from marula fruit, which is the proposed ancestral food host of D. melanogaster. We found that wild flies were preferentially attracted to banana-based odorants over marula-derived ones. Overall, these traps and attractants represent an inexpensive and simple option for the collection of wild D. melanogaster and related species for sampling or colony establishment.

Two of the most important environmental factors that affect the sperm competitive ability in males are the availability of resources and the socio-sexual environment. Numerous studies have investigated the individual effects of these factors, but their combined effect on the evolution of sperm competitive ability remains untested. A crowded larval environment is unique because it simultaneously affects the fitness of the organism through both resource availability and the socio-sexual environment. In this study, we used a set of four laboratory populations of D. melanogaster, evolved under a crowded larval environment for more than 165 generations and their respective controls to investigate how the sperm competitive ability of the males is affected by a single generation of larval crowding versus evolution under a crowded larval environment for more than 165 generations. Our results show that larval crowding negatively affects the sperm defence ability of males evolved in a crowded larval environment, while it has no effect on the sperm defence ability of control males. Additionally, larval crowding negatively impacts the sperm offence ability in both control and evolved populations. Males from populations adapted to a crowded larval environment exhibit lower sperm offence ability at an older age compared to control populations.

Drosophila melanogaster is a widely used model organism for diseases such as Parkinson's disease, Alzheimer's disease, obesity, and diabetes. However, compound administration-based toxicological and behavioural studies on Drosophila have been hindered by technical difficulties associated with inefficient administration of hydrophobic compounds. This study illustrates a general method to make and distribute PEG 8000-based solid dispersions for three hydrophobic compounds, distearoylglycerol (DSG) geldanamycin (GA) and RU486 to D. melanogaster. The solid dispersions were validated, in vitro, using nuclear magnetic resonance spectroscopy (NMR), to have a higher aqueous solubility. The study also describes three different methods to administer the solid dispersions: subcutaneous injections, mixing in solid food, and the capillary feeder assay (CAFE). We show that the presence of 1% DMSO decreases survival, whereas PEG does not have an adverse effect. Lastly, we showed that the prepared PEG-RU486 formulation showed signs of enhanced bioavailability when compared to RU486 dissolved in ethanol. The methodology described in the study provides an easy and effective means to administer hydrophobic compounds to D. melanogaster using subcutaneous injections, CAFE assay, or by mixing it with solid food.

This study investigates the effects of polyglutamine (polyQ) expansions on the locomotion of Drosophila larvae, focusing on the role of class IV dendritic arborization (da) neurons. PolyQ expansions are associated with neurodegenerative diseases like Huntington's disease, and Drosophila is a valuable model organism for studying these diseases due to its genetic tractability and short generation time. We found that expressing a polyQ protein in class IV da neurons caused significant locomotion deficits. Specifically, larvae with polyQ expression exhibited slower crawling speed and increased turn frequency, indicating impaired movement. The most intriguing finding of our study was that electrically silencing class IV da neurons completely rescued the locomotion deficits caused by polyQ expression. By expressing a potassium channel that makes the neurons less active, we effectively reversed the locomotion defects. This suggests that modulating the activity of these neurons could be a promising therapeutic approach for treating polyQ diseases. Our findings have significant implications for understanding polyQ diseases and developing new therapeutic approaches. By electrically silencing these neurons, we may be preventing the harmful effects of polyQ-induced cation channels, which are thought to disrupt cellular function. This opens up exciting possibilities for exploring electrical silencing as a potential treatment for polyQ diseases, offering hope for future therapies that target the underlying mechanisms of these devastating conditions.

Drosophila melanogaster is an incredible model system, providing tools and technologies that allow careful, effective, and reproducible research. This experimental approach, and the genetic tools and techniques available in Drosophila are desperately needed for the study of other insects, a hugely diverse group of huge importance to natural and productive ecosystems. For those of you with the skills and 'Drosophila mindset', studying other insects may help us understand diversity, improve the security of food production, and help avoid the current, worrying, insect apocalypse.

Proper formation and specification of Primordial Germ Cells (PGCs) is of special significance as they gradually transform into Germline Stem Cells (GSCs) that are ultimately responsible for generating the gametes. Intriguingly, not only the PGCs constitute the only immortal cell type but several specific determinants also underlying PGC specification such as Vasa, Nanos and Germ-cell-less are conserved through evolution. In Drosophila melanogaster, PGC formation and specification depends on two independent factors, the maternally deposited specialized cytoplasm (or germ plasm) enriched in germline determinants, and the mechanisms that execute the even partitioning of these determinants between the daughter cells. Prior work has shown that Oskar protein is necessary and sufficient to assemble the functional germ plasm, whereas centrosomes associated with the nuclei that invade the germ plasm are responsible for its equitable distribution. Our recent data suggests that Caspar, the Drosophila orthologue of human Fas-associated factor-1 (FAF1) is a novel regulator that modulates both mechanisms that underlie the determination of PGC fate. Consistently, early blastoderm embryos derived from females compromised for caspar display reduced levels of Oskar and defective centrosomes.

Drosophila pseudoobscura and D. persimilis are a sister species pair that have been used as a model for studies of reproductive isolation and speciation for almost 100 years owing to their close evolutionary history, well characterized genetic differences, and overlapping geographic distribution. There are extensive analyses of both pre- and post-zygotic isolation, including studies of courtship divergence, conspecific sperm precedence (CSP) and how reinforcement by natural selection may or may not act to strengthen isolation in sympatry. Post-zygotic analyses explore the underlying mechanics of reproductive isolation; how inversions may give rise to initial speciation events and misexpression of key genes typically found within inversion regions render hybrid offspring unfit or inviable. We aim here to present a history of studies of reproductive isolation between this species pair, looking at how the field has developed over the last century and identifying the open questions and gaps within the literature.

The in situ hybridization chain reaction (isHCR) is a powerful method for visualizing mRNA in many species. We present a rapid isHCR method for Drosophila embryos and ovaries. Ethylene carbonate was added to the hybridization buffer to facilitate the hybridization reaction, and a modified short hairpin DNA was used in the amplification reaction; these modifications decreased the RNA staining time from 3 days to 1 day. This method is compatible with immunohistochemistry and can detect multiple mRNAs. The proposed method could significantly reduce staining time for Drosophila researchers using isHCR.