Project description:Background:Calcium signaling are conserved from invertebrates to vertebrates and plays critical roles in many molecular mechanisms of embryogenesis and postnatal development. As a critical component of the signaling pathway, the RyR medicated calcium-induced calcium release signaling system, has been well studied along with their regulator FK506-binding protein 12 (FKBP12/Calstabin). Lack of FKBP12 is known to result in lethal cardiac dysfunction in mouse. However, precisely how FKBP12 is regulated and effects calcium signaling in Drosophila melanogaster remains largely unknown. Results:In this study, we identified both temporal and localization changes in expression of DmFKBP12, a translational and transcriptional regulator of Drosophila RyR (DmRyR) and FKBP12, through embryonic development. DmFKBP12 is first expressed at the syncytial blastoderm stage and undergoes increased expression during the cellular blastoderm and early gastrulation stages. At late gastrulation, DmFKBP12 expression begins to decline until it reaches homeostasis, which it then maintains throughout the rest of development. Throughout these described changes in expression, DmFKBP12 mRNA remain stable, which indicates that protein dynamics are attributed to regulation at the mRNA to protein translation level. In addition to temporal changes in expression, dynamic expression profiles during Drosophila development also revealed DmFKBP12 localization. Although DmFKBP12 is distributed evenly between the anterior to posterior poles of the blastoderm egg, the protein is expressed more strongly in the cortex of the early Drosophila gastrula with the highest concentration found in the basement membrane of the cellular blastoderm. Fertilized egg, through the profile as under-membrane cortex distribution concentering onto basement at cellular blastoderm, to the profile as three-gem layer localization in primitive neuronal and digestion architecture of early Drosophila gastrula. By late gastrulation, DmFKBP12 is no longer identified in the yolk or lumen of duct structures and has relocated to the future brain (suboesophageal and supraesophageal ganglions), ventral nervous system, and muscular system. Throughout these changes in distribution, in situ DmFKBP12 mRNA monitoring detected equal distribution of DmFKBP12 mRNA, once again indicating that regulation of DmFKBP12 occurs at the translational level in Drosophila development. Conclusion:As a critical regulator of the DmRyR-FKBP complex, DmFKBP12 expression in Drosophila fluctuates temporally and geographically with the formation of organ systems. These finding indicate that DmFKBP12 and RyR associated calcium signaling plays an essential role in the successful development of Drosophila melanogaster. Further study on the differences between mammalian RyR-FKBP12 and Drosophila DmRyR-FKBP12 can be exploited to develop safe pesticides.
Project description:Although it is well established that cis-acting regulatory variation contributes to morphological evolution between species, few concrete examples of polymorphism affecting developmental patterning within species have been demonstrated. Early embryogenesis in Drosophila is initiated by a gradient of Bicoid morphogen activity that results in differential expression of multiple target genes. In a screen for genetic variation affecting this process, we surveyed 96 wild-type lines of Drosophila melanogaster for polymorphisms in binding sites within 16 Bicoid cis-regulatory response elements. One common polymorphism in the orthodenticle (otd) early head enhancer is associated with a complex series of indels/substitutions that define two distinct haplotypes. The middle region of this enhancer exhibits an unusual pattern of nucleotide diversity that does not easily fit into standard models of selection and demography. Population Gene Expression Maps, generated by extracting binary expression profiles from normalized embryo images, revealed a ventral reduction of otd transcript abundance in one of the haplotypes that was recapitulated in expression of transgenic constructs containing the two alleles. We thus demonstrate that even a process as robust as early developmental patterning is affected by standing genetic variation, intriguingly involving otd, whose morphogenetic function bicoid is thought to have displaced during dipteran evolution.
Project description:Nuclear composition determines nuclear function. The early embryos of many species begin life with large pools of maternally provided components that become rapidly imported into an increasing number of nuclei as the cells undergo repeated cleavage divisions. Because early cell cycles are too fast for nuclei to achieve steady-state nucleocytoplasmic partitioning, the composition of cleavage stage nuclei is likely dominated by nuclear import. The end of the rapid cleavage stage and onset of major zygotic transcription, known as the mid-blastula transition (MBT), is controlled by the ratio of nuclei/cytoplasm, indicating that changes in nuclear composition likely mediate MBT timing. Here, we explore how different nuclear import regimes can affect protein accumulation in the nucleus in the early Drosophila embryo. We find that nuclear import differs dramatically for a general nuclear cargo (NLS (nuclear localization signal)-mRFP) and a proposed MBT regulator (histone H3). We show that nuclear import rates of NLS-mRFP in a given nucleus remain relatively unchanged throughout the cleavage cycles, whereas those of H3 halve with each cycle. We model these two distinct modes of nuclear import as "nucleus-limited" and "import-limited" and examine how the two different modes can contribute to different protein accumulation dynamics. Finally, we incorporate these distinct modes of nuclear import into a model for cell-cycle regulation at the MBT and find that the import-limited H3 dynamics contribute to increased robustness and allow for stepwise cell-cycle slowing at the MBT.
Project description:The nucleus is a highly structured organelle and contains many functional compartments. Although the structural basis for this complex spatial organization of compartments is unknown, a major component of this organization is likely to be the non-chromatin scaffolding called nuclear matrix (NuMat). Experimental evidence over the past decades indicates that most of the nuclear functions are at least transiently associated with the NuMat, although the components of NuMat itself are poorly known. Here, we report NuMat proteome analysis from Drosophila melanogaster embryos and discuss its links with nuclear architecture and functions. In the NuMat proteome, we found structural proteins, chaperones, DNA/RNA-binding proteins, chromatin remodeling and transcription factors. This complexity of NuMat proteome is an indicator of its structural and functional significance. Comparison of the two-dimensional profile of NuMat proteome from different developmental stages of Drosophila embryos showed that less than half of the NuMat proteome is constant, and the rest of the proteins are stage-specific dynamic components. These NuMat dynamics suggest a possible functional link between NuMat and embryonic development. Finally, we also showed that a subset of NuMat proteins remains associated with the mitotic chromosomes, implicating their role in mitosis and possibly the epigenetic cellular memory. NuMat proteome analysis provides tools and opens up ways to understand nuclear organization and function.
Project description:Nuclear and mitochondrial organelles must maintain a communication system. Loci on the mitochondrial genome were recently reported to interact with nuclear loci. To determine whether this is part of a DNA based communication system we used genome conformation capture to map the global network of DNA-DNA interactions between the mitochondrial and nuclear genomes (Mito-nDNA) in Saccharomyces cerevisiae cells grown under three different metabolic conditions. The interactions that form between mitochondrial and nuclear loci are dependent on the metabolic state of the yeast. Moreover, the frequency of specific mitochondrial-nuclear interactions (i.e. COX1-MSY1 and Q0182-RSM7) showed significant reductions in the absence of mitochondrial encoded reverse transcriptase machinery. Furthermore, these reductions correlated with increases in the transcript levels of the nuclear loci (MSY1 and RSM7). We propose that these interactions represent an inter-organelle DNA mediated communication system and that reverse transcription of mitochondrial RNA plays a role in this process.
Project description:Nuclear and mitochondrial organelles must maintain a communication system. Loci on the mitochondrial genome were recently reported to interact with nuclear loci. To determine whether this is part of a DNA based communication system we used genome conformation capture to map the global network of DNA-DNA interactions between the mitochondrial and nuclear genomes (Mito-nDNA) in Saccharomyces cerevisiae cells grown under three different metabolic conditions. The interactions that form between mitochondrial and nuclear loci are dependent on the metabolic state of the yeast. Moreover, the frequency of specific mitochondrial - nuclear interactions (i.e. COX1-MSY1 and Q0182-RSM7) showed significant reductions in the absence of mitochondrial encoded reverse transcriptase machinery. Furthermore, these reductions correlated with increases in the transcript levels of the nuclear loci (MSY1 and RSM7). We propose that these interactions represent an inter-organelle DNA mediated communication system and that reverse transcription of mitochondrial RNA plays a role in this process. This SuperSeries is composed of the SubSeries listed below. Refer to individual Series.
Project description:Courtship in Drosophila melanogaster has become an iconic example of an innate and interactive series of behaviors. The female signals her acceptance of copulation by becoming immobile in response to a male's display of stereotyped actions. The male and female communicate via vision, air-borne sounds, and pheromones, but what triggers the female's immobility is undetermined. Here, we describe an overlooked and important component of Drosophila courtship. Video recordings and laser vibrometry show that the male abdomen shakes ("quivers"), generating substrate-borne vibrations at about six pulses per second. We present evidence that the female becomes receptive and stops walking because she senses these vibrations, rather than as a response to air-borne songs produced by the male fluttering the wings. We also present evidence that the neural circuits expressing the sex-determination genes fruitless and doublesex drive quivering behavior. These abdominal quivers and associated vibrations, as well as their effect on female receptivity, are conserved in other Drosophila species. Substrate-borne vibrations are an ancient form of communication that is widespread in animals. Our findings in Drosophila open a door to study the neuromuscular circuitry responsible for these signals and the sensory systems needed for their reception.
Project description:Characterizing and understanding the complex spectrum of lipids in higher organisms lags far behind our analysis of genome and transcriptome sequences. Here we generate and evaluate comprehensive lipid profiles (>200 lipids) of 92 inbred lines from five different Drosophila melanogaster populations. We find that the majority of lipid species are highly heritable, and even lipids with odd-chain fatty acids, which cannot be generated by the fly itself, also have high heritabilities. Abundance of the endosymbiont Wolbachia, a potential provider of odd-chained lipids, was positively correlated with this group of lipids. Additionally, we show that despite years of laboratory rearing on the same medium, the lipid profiles of the five geographic populations are sufficiently distinct for population discrimination. Our data predicts a strikingly different membrane fluidity for flies from the Netherlands, which is supported by their increased ethanol tolerance. We find that 18% of lipids show strong concentration differences between males and females. Through an analysis of the correlation structure of the lipid classes, we find modules of co-regulated lipids and begin to associate these with metabolic constraints. Our data provide a foundation for developing associations between variation in lipid composition with variation in other metabolic attributes, with genome-wide variation, and with metrics of health and overall reproductive fitness.
Project description:Previous studies of the evolution of genes expressed at different life-cycle stages of Drosophila melanogaster have not been able to disentangle adaptive from nonadaptive substitutions when using nonsynonymous sites. Here, we overcome this limitation by combining whole-genome polymorphism data from D. melanogaster and divergence data between D. melanogaster and Drosophila yakuba. For the set of genes expressed at different life-cycle stages of D. melanogaster, as reported in modENCODE, we estimate the ratio of substitutions relative to polymorphism between nonsynonymous and synonymous sites (α) and then α is discomposed into the ratio of adaptive (ωa) and nonadaptive (ωna) substitutions to synonymous substitutions. We find that the genes expressed in mid- and late-embryonic development are the most conserved, whereas those expressed in early development and postembryonic stages are the least conserved. Importantly, we found that low conservation in early development is due to high rates of nonadaptive substitutions (high ωna), whereas in postembryonic stages it is due, instead, to high rates of adaptive substitutions (high ωa). By using estimates of different genomic features (codon bias, average intron length, exon number, recombination rate, among others), we also find that genes expressed in mid- and late-embryonic development show the most complex architecture: they are larger, have more exons, more transcripts, and longer introns. In addition, these genes are broadly expressed among all stages. We suggest that all these genomic features are related to the conservation of mid- and late-embryonic development. Globally, our study supports the hourglass pattern of conservation and adaptation over the life-cycle.
Project description:In eukaryotic genomes, ribosomal RNA (rRNA) genes exist as tandemly repeated clusters, forming ribosomal DNA (rDNA) loci. Each rDNA locus typically contains hundreds of rRNA genes to meet the high demand of ribosome biogenesis. Nucleolar dominance is a phenomenon whereby individual rDNA loci are entirely silenced or transcribed, and is believed to be a mechanism to control rRNA dosage. Nucleolar dominance was originally noted to occur in interspecies hybrids, and has been shown to occur within a species (i.e, nonhybrid context). However, studying nucleolar dominance within a species has been challenging due to the highly homogenous sequence across rDNA loci. By utilizing single nucleotide polymorphisms between X rDNA and Y rDNA loci in males, as well as sequence variations between two X rDNA loci in females, we conducted a thorough characterization of nucleolar dominance throughout development of Drosophila melanogaster We demonstrate that nucleolar dominance is a developmentally regulated program that occurs in nonhybrid, wild-type D. melanogaster, where Y rDNA dominance is established during male embryogenesis, whereas females normally do not exhibit dominance between two X rDNA loci. By utilizing various chromosomal complements (e.g., X/Y, X/X, X/X/Y) and a chromosome rearrangement, we show that the short arm of the Y chromosome including the Y rDNA likely contains information that instructs the state of nucleolar dominance. Our study begins to reveal the mechanisms underlying the selection of rDNA loci for activation/silencing in nucleolar dominance in the context of nonhybrid D. melanogaster.