RESUMEN
Despite increasing in mass approximately 100-fold during larval life, the Drosophila CNS maintains its characteristic form. Dynamic interactions between the overlying basement membrane and underlying surface glia are known to regulate CNS structure in Drosophila, but the genes and pathways that establish and maintain CNS morphology during development remain poorly characterized. To identify genes that regulate CNS shape in Drosophila, we conducted an EMS-based, forward genetic screen of the second chromosome, uncovered 50 mutations that disrupt CNS structure, and mapped these alleles to 17 genes. Analysis of whole genome sequencing data wedded to genetic studies uncovered the affected gene for all but 1 mutation. Identified genes include well-characterized regulators of tissue shape, like LanB1, viking, and Collagen type IV alpha1, and previously characterized genes, such as Toll-2 and Rme-8, with no known role in regulating CNS structure. We also uncovered that papilin and C1GalTA likely act in the same pathway to regulate CNS structure and found that the fly homolog of a glucuronosyltransferase, B4GAT1/LARGE1, that regulates Dystroglycan function in mammals is required to maintain CNS shape in Drosophila. Finally, we show that the senseless-2 transcription factor is expressed and functions specifically in surface glia found on peripheral nerves but not in the CNS to govern CNS structure, identifying a gene that functionally subdivides a glial subtype along the peripheral-central axis. Future work on these genes should clarify the genetic mechanisms that ensure the homeostasis of CNS form during development.
Asunto(s)
Proteínas de Drosophila , Drosophila melanogaster , Mutación , Factores de Transcripción , Animales , Alelos , Sistema Nervioso Central/metabolismo , Drosophila/genética , Drosophila melanogaster/genética , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Pruebas Genéticas , Neuroglía/metabolismo , Sistema Nervioso Periférico/metabolismo , Fenotipo , Factores de Transcripción/metabolismoRESUMEN
Butterfly wings display a diversity of cell types, including large polyploid scale cells, yet the molecular basis of such diversity is poorly understood. To explore scale cell diversity at a transcriptomic level, we employ single-cell RNA sequencing of â¼5,200 large cells (>6 µm) from 22.5- to 25-h male pupal forewings of the butterfly Bicyclus anynana. Using unsupervised clustering, followed by in situ hybridization, immunofluorescence, and CRISPR-Cas9 editing of candidate genes, we annotate various cell types on the wing. We identify genes marking non-innervated scale cells, pheromone-producing glandular cells, and innervated sensory cell types. We show that senseless, a zinc-finger transcription factor, and HR38, a hormone receptor, determine the identity, size, and color of different scale cell types and are important regulators of scale cell differentiation. This dataset and the identification of various wing cell-type markers provide a foundation to compare and explore scale cell-type diversification across arthropod species.
Asunto(s)
Mariposas Diurnas , Pupa , Análisis de la Célula Individual , Alas de Animales , Animales , Mariposas Diurnas/genética , Alas de Animales/metabolismo , Alas de Animales/citología , Pupa/metabolismo , Análisis de la Célula Individual/métodos , Masculino , Proteínas de Insectos/genética , Proteínas de Insectos/metabolismo , Transcriptoma/genéticaRESUMEN
The Drosophila melanogaster peripheral nervous system (PNS) comprises the sensory organs that allow the fly to detect environmental factors such as temperature and pressure. PNS development is a highly specified process where each sensilla originates from a single sensory organ precursor (SOP) cell. One of the major genetic orchestrators of PNS development is Senseless, which encodes a zinc finger transcription factor (Sens). Sens is both necessary and sufficient for SOP differentiation. Senseless expression and SOP number are regulated by the microRNA miR-9a. However, the reciprocal dynamics of Senseless and miR-9a are still obscure. By coupling single-molecule FISH with immunofluorescence, we are able to visualize transcription of the mir-9a locus and expression of Sens simultaneously. During embryogenesis, we show that the expression of mir-9a in SOP cells is rapidly lost as Senseless expression increases. However, this mutually exclusive expression pattern is not observed in the third instar imaginal wing disk, where some Senseless-expressing cells show active sites of mir-9a transcription. These data challenge and extend previous models of Senseless regulation and show complex co-expression dynamics between mir-9a and Senseless. The differences in this dynamic relationship between embryonic and larval PNS development suggest a possible switch in miR-9a function. Our work brings single-cell resolution to the understanding of dynamic regulation of PNS development by Senseless and miR-9a.
Asunto(s)
Proteínas de Drosophila/genética , Drosophila melanogaster/embriología , Larva/crecimiento & desarrollo , MicroARNs , Proteínas Nucleares/genética , Factores de Transcripción/genética , Animales , Drosophila melanogaster/genética , Regulación del Desarrollo de la Expresión Génica , Sistema Nervioso Periférico , Análisis de la Célula IndividualRESUMEN
This article offers an analytic, integrative review of select themes associated with one of history's greatest atrocities: the Holocaust. Much of this review considers general and Holocaust-specific themes as they pertain to the nature of senseless violence and evil. The importance of having a greater understanding of the sheer brutality of violence perpetuated in the Holocaust is emphasized. As part of this discussion, considerable attention is given to how Internet-based photographs and videos from the Holocaust era can provide greater insight into understanding the evil associated with this genocide. Some consideration of the larger meaning of the Holocaust, particularly for Jews, is also examined.
Asunto(s)
Genocidio/historia , Genocidio/psicología , Holocausto/historia , Holocausto/psicología , Judíos/historia , Judíos/psicología , Violencia/historia , Violencia/psicología , Alemania , Historia del Siglo XXRESUMEN
Wnt/ß-catenin and hedgehog (Hh) signaling are essential for transmitting signals across cell membranes in animal embryos. Early patterning of the principal insect model, Drosophila melanogaster, occurs in the syncytial blastoderm, where diffusion of transcription factors obviates the need for signaling pathways. However, in the cellularized growth zone of typical short germ insect embryos, signaling pathways are predicted to play a more fundamental role. Indeed, the Wnt/ß-catenin pathway is required for posterior elongation in most arthropods, although which target genes are activated in this context remains elusive. Here, we use the short germ beetle Tribolium castaneum to investigate two Wnt and Hh signaling centers located in the head anlagen and in the growth zone of early embryos. We find that Wnt/ß-catenin signaling acts upstream of Hh in the growth zone, whereas the opposite interaction occurs in the head. We determine the target gene sets of the Wnt/ß-catenin and Hh pathways and find that the growth zone signaling center activates a much greater number of genes and that the Wnt and Hh target gene sets are essentially non-overlapping. The Wnt pathway activates key genes of all three germ layers, including pair-rule genes, and Tc-caudal and Tc-twist. Furthermore, the Wnt pathway is required for hindgut development and we identify Tc-senseless as a novel hindgut patterning gene required in the early growth zone. At the same time, Wnt acts on growth zone metabolism and cell division, thereby integrating growth with patterning. Posterior Hh signaling activates several genes potentially involved in a proteinase cascade of unknown function.