Fly最新文献

Drosophila melanogaster chromosome 4 is an anomaly because of its small size, chromatin structure, and most notably its lack of crossing over during meiosis. Earlier ideas about the absence of crossovers on 4 hypothesize that these unique characteristics function to prevent crossovers. Here, we explore hypotheses about the absence of crossovers on 4, how these have been addressed, and new insights into the mechanism behind this suppression. We review recently published results that indicate that global crossover patterning, in particular the centromere effect, make a major contribution to the prevention of crossovers on 4.

The Hippo signaling pathway regulates organ size and tissue homeostasis. Given this role it is unsurprising that dysregulation of this pathway has implications for cancer progression. A convincing body of literature shows that the Hippo pathway serves a tumor suppressive function with its inactivation leading to massive overgrowth. However, additional studies have also shown that activation of Hippo signaling can promote tumor progression. It remains unknown how a single pathway can produce such diametrically opposed effects. This lack of knowledge is in part due to our inability to make meaningful comparisons from studies which have taken place in a variety of cell types, tissues, and organisms. Recently however, we have published 2 studies using the Drosophila wing disk to study the Hippo pathway and have found that Hippo pathway activation can promote cell migration and invasion while Hippo pathway inactivation leads to overgrowth. Thus we propose here that Drosophila can provide a research platform with which to begin addressing how the Hippo pathway can both enhance and suppress tumor progression due to published pro- and anti-tumor functionalities of the Hippo pathway in the same tissue.

As environments and pathogen landscapes shift, host defenses must evolve to remain effective. Due to this selection pressure, among-species comparisons of genetic sequence data often find immune genes to be among the fastest evolving genes across the genome. The full extent and nature of these immune adaptations, however, remain largely unexplored. In a recent study, we analyzed patterns of selection within distinct components of the Drosophila melanogaster immune pathway. While we found evidence of positive selection within some immune processes, immune genes were not universally characterized by signatures of strong selection. On the contrary, we even found that some immune functions show greater than expected constraint. Overall these results highlight 2 major factors that appear to play an outsize role in determining a gene's evolutionary rate: the type of pathogen the gene targets and the gene's position within the immune network. These results join a growing body of literature that highlight the complexity of immune adaptation. Rather than there being uniformly strong selection across all immune genes, a combination of pathogen-specificity and host genetic constraints appear to play key roles in determining each immune gene's individual evolutionary trajectory.

Myoglianin, the Drosophila homolog of the secreted vertebrate proteins Myostatin and GDF-11, is an important regulator of neuronal modeling, and synapse function and morphology. While Myoglianin suppression during development elicits positive effects on the neuromuscular system, genetic manipulations of myoglianin expression levels have a varied effect on the outcome of performance tests in aging flies. Specifically, Myoglianin preserves jumping ability, has no effect on negative geotaxis, and negatively regulates flight performance in aging flies. In addition, Myoglianin exhibits a tissue-specific effect on longevity, with myoglianin upregulation in glial cells increasing the median lifespan. These findings indicate complex role for this TGF-β-like protein in governing neuromuscular signaling and consequent behavioral outputs and lifespan in adult flies.

The Abelson tyrosine kinase (Abl) lies at the heart of one of the small set of ubiquitous, conserved signal transduction pathways that do much of the work of development and physiology. Abl signaling is essential to epithelial integrity, motility of autonomous cells such as blood cells, and axon growth and guidance in the nervous system. However, though Abl was one of the first of these conserved signaling machines to be identified, it has been among the last to have its essential architecture elucidated. Here we will first discuss some of the challenges that long delayed the dissection of this pathway, and what they tell us about the special problems of investigating dynamic processes like motility. We will then describe our recent experiments that revealed the functional organization of the Abl pathway in Drosophila neurons. Finally, in the second part of the review we will introduce a different kind of complexity in the role of Abl in motility: the discovery of a previously unappreciated function in protein secretion and trafficking. We will provide evidence that the secretory function of Abl also contributes to its role in axon growth and guidance, and finally end with a discussion of the challenges that Abl pleiotropy provide for the investigator, but the opportunities that it provides for coordinating biological regulation.

The inositol 1,4,5-trisphosphate receptor (IP₃R) is one of two Ca²⁺ channels that gates Ca²⁺ release from ER-stores. The ligand IP₃, generated upon specific G-protein coupled receptor activation, binds to IP₃R to release Ca²⁺ into the cytosol. IP₃R also mediates ER-store Ca²⁺ release into the mitochondria, under basal as well as stimulatory conditions; an activity that influences cellular bioenergetics and thus, cellular growth and proliferation. In Drosophila neuroendocrine cells expressing a hypomorphic mutant of IP₃R, we observed reduced protein translation levels. Here, we discuss the possible molecular mechanism for this observation. We hypothesise that the cellular energy sensor, AMPK connects IP₃R mediated Ca²⁺ release into the mitochondria, to protein translation, via the TOR pathway.

Understanding the computations that take place in neural circuits requires identifying how neurons in those circuits are connected to one another. In addition, recent research indicates that aberrant neuronal wiring may be the cause of several neurodevelopmental disorders, further emphasizing the importance of identifying the wiring diagrams of brain circuits. To address this issue, several new approaches have been recently developed. In this review, we describe several methods that are currently available to investigate the structure and connectivity of the brain, and discuss their strengths and limitations.

The exoskeleton of insects and other arthropods is a very versatile material that is characterized by a complex multilayer structure. In Sobala and Adler (2016) we analyzed the process of wing cuticle deposition by RNAseq and electron microscopy. In this extra view we discuss the unique aspects of the envelope the first and most outermost layer and the gene expression program seen at the end of cuticle deposition. We discussed the role of undulae in the deposition of cuticle and how the hydrophobicity of wing cuticle arises.

Diet profoundly influences the behavior of animals across many phyla. Despite this, most laboratories using model organisms, such as Drosophila, use multiple, different, commercial or custom-made media for rearing their animals. In addition to measuring growth, fecundity and longevity, we used several behavioral and physiological assays to determine if and how altering food media influence wild-type (Canton S) Drosophila melanogaster, at larval, pupal, and adult stages. Comparing 2 commonly used commercial food media we observed several key developmental and morphological differences. Third-instar larvae and pupae developmental timing, body weight and size, and even lifespan significantly differed between the 2 diets, and some of these differences persisted into adulthood. Diet was also found to produce significantly different thermal preference, locomotory capacity for geotaxis, feeding rates, and lower muscle response to hormonal stimulation. There were no differences, however, in adult thermal preferences, in the number or viability of eggs laid, or in olfactory learning and memory between the diets. We characterized the composition of the 2 diets and found particularly significant differences in cholesterol and (phospho)lipids between them. Notably, diacylglycerol (DAG) concentrations vary substantially between the 2 diets, and may contribute to key phenotypic differences, including lifespan. Overall, the data confirm that 2 different diets can profoundly influence the behavior, physiology, morphology and development of wild-type Drosophila, with greater behavioral and physiologic differences occurring during the larval stages.

The germline stem cells (GSCs) are critical for gametogenesis throughout the adult life. Stem cell identity is maintained by local signals from a specialized microenvironment called the niche. However, it is unclear how systemic signals regulate stem cell activity in response to environmental cues. In our previous article, we reported that mating stimulates GSC proliferation in female Drosophila. The mating-induced GSC proliferation is mediated by ovarian ecdysteroids, whose biosynthesis is positively controlled by Sex peptide signaling. Here, we characterized the post-eclosion and post-mating expression pattern of the genes encoding the ecdysteroidogenic enzymes in the ovary. We further investigated the biosynthetic functions of the ovarian ecdysteroid in GSC maintenance in the mated females. We also briefly discuss the regulation of the ecdysteroidogenic enzyme-encoding genes and the subsequent ecdysteroid biosynthesis in the ovary of the adult Drosophila.