RESUMO
Key scientific discoveries have resulted from genetic studies of Drosophila melanogaster, using a multitude of transgenic fly strains, the majority of which are constructed in a genetic background containing mutations in the white gene. Here we report that white mutant flies from w1118 strain undergo retinal degeneration. We observed also that w1118 mutants have progressive loss of climbing ability, shortened life span, as well as impaired resistance to various forms of stress. Retinal degeneration was abolished by transgenic expression of mini-white+ in the white null background w1118 . We conclude that beyond the classical eye-color phenotype, mutations in Drosophila white gene could impair several biological functions affecting parameters like mobility, life span and stress tolerance. Consequently, we suggest caution and attentiveness during the interpretation of old experiments employing white mutant flies and when planning new ones, especially within the research field of neurodegeneration and neuroprotection. We also encourage that the use of w1118 strain as a wild-type control should be avoided.
RESUMO
Regulation of transcription is one of the mechanisms involved in animal development, directing changes in patterning and cell fate specification. Large temporal data series, based on microarrays across the life cycle of the fly Drosophila melanogaster, revealed the existence of groups of genes which expression increases or decreases temporally correlated during the life cycle. These groups of genes are enriched in different biological functions. Here, instead of searching for temporal coincidence in gene expression using the entire genome expression data, we searched for temporal coincidence in gene expression only within predefined catalogues of functionally related genes and investigated whether a catalogue's expression profile can be used to generate larger catalogues, enriched in genes necessary for the same function. We analyzed the expression profiles from genes already associated with early neurodevelopment and late neurodifferentiation, at embryonic stages 16 and 17 of Drosophila life cycle. We hypothesized that during this interval we would find global downregulation of genes important for early neuronal development together with global upregulation of genes necessary for the final differentiation of neurons. Our results were consistent with this hypothesis. We then investigated if the expression profile of gene catalogues representing particular processes of neural development matched the temporal sequence along which these processes occur. The profiles of genes involved in patterning, neurogenesis, axogenesis or synaptic transmission matched the prediction, with largest transcript values at the time when the corresponding biological process takes place in the embryo. Furthermore, we obtained catalogues enriched in genes involved in temporally matching functions by performing a genome-wide systematic search for genes with their highest expression levels at the corresponding embryonic intervals. These findings imply the use of gene expression data in combination with known biological information to predict the involvement of functionally uncharacterized genes in particular biological events.
Assuntos
Drosophila melanogaster/genética , Neurogênese/genética , Neurônios/fisiologia , Animais , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/embriologia , Drosophila melanogaster/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Ontologia Genética , Metamorfose Biológica/genética , TranscriptomaRESUMO
Previous studies have shown that the morphology of the neuromuscular junction of the flight motor neuron MN5 in Drosophila melanogaster undergoes daily rhythmical changes, with smaller synaptic boutons during the night, when the fly is resting, than during the day, when the fly is active. With electron microscopy and laser confocal microscopy, we searched for a rhythmic change in synapse numbers in this neuron, both under light:darkness (LD) cycles and constant darkness (DD). We expected the number of synapses to increase during the morning, when the fly has an intense phase of locomotion activity under LD and DD. Surprisingly, only our DD data were consistent with this hypothesis. In LD, we found more synapses at midnight than at midday. We propose that under LD conditions, there is a daily rhythm of formation of new synapses in the dark phase, when the fly is resting, and disassembly over the light phase, when the fly is active. Several parameters appeared to be light dependent, since they were affected differently under LD or DD. The great majority of boutons containing synapses had only one and very few had either two or more, with a 70â¶25â¶5 ratio (one, two and three or more synapses) in LD and 75â¶20â¶5 in DD. Given the maintenance of this proportion even when both bouton and synapse numbers changed with time, we suggest that there is a homeostatic mechanism regulating synapse distribution among MN5 boutons.
Assuntos
Drosophila melanogaster/citologia , Neurônios Motores/fisiologia , Junção Neuromuscular/fisiologia , Terminações Pré-Sinápticas/fisiologia , Animais , Ritmo Circadiano , Drosophila melanogaster/fisiologia , Feminino , Microscopia Confocal , Microscopia Eletrônica de Transmissão , Neurônios Motores/ultraestrutura , Junção Neuromuscular/ultraestrutura , Fotoperíodo , Terminações Pré-Sinápticas/ultraestruturaRESUMO
BACKGROUND: Neurodegenerative diseases are progressive and irreversible and they can be initiated by mutations in specific genes. Spalt-like genes (Sall) encode transcription factors expressed in the central nervous system. In humans, SALL mutations are associated with hereditary syndromes characterized by mental retardation, sensorineural deafness and motoneuron problems, among others. Drosophila sall mutants exhibit severe neurodegeneration of the central nervous system at embryonic stage 16, which surprisingly reverts later in development at embryonic stage 17, suggesting a potential to recover from neurodegeneration. We hypothesize that this recovery is mediated by a reorganization of the transcriptome counteracting SALL lost. To identify genes associated to neurodegeneration and neuroprotection, we used mRNA-Seq to compare the transcriptome of Drosophila sall mutant and wild type embryos from neurodegeneration and reversal stages. RESULTS: Neurodegeneration stage is associated with transcriptional changes in 220 genes, of which only 5% were already described as relevant for neurodegeneration. Genes related to the groups of Redox, Lifespan/Aging and Mitochondrial diseases are significantly represented at this stage. By contrast, neurodegeneration reversal stage is associated with significant changes in 480 genes, including 424 not previously associated with neuroprotection. Immune response and Salt stress are the most represented groups at this stage. CONCLUSIONS: We identify new genes associated to neurodegeneration and neuroprotection by using an mRNA-Seq approach. The strong homology between Drosophila and human genes raises the possibility to unveil novel genes involved in neurodegeneration and neuroprotection also in humans.
Assuntos
Proteínas de Drosophila/genética , Drosophila/genética , Doenças Neurodegenerativas/genética , Transcriptoma , Animais , Biologia Computacional , Drosophila/embriologia , Regulação da Expressão Gênica no Desenvolvimento , Genes de Insetos , Análise de Sequência de RNARESUMO
The morphology of Drosophila motor terminals changes along the day with a circadian rhythm controlled by the biological clock. Here, we used electron microscopy to investigate the size, number, and distribution of synaptic vesicles, at intervals of 6 h during 2 consecutive days, under light-dark (LD) or the first 2 days in constant darkness (DD). We found changes in the size and distribution of vesicles located either at the active zone or in the reserve pool, indicating a circadian rhythm of synapse reorganization. Vesicles at the active zone were generally smaller than those in the reserve pool in LD and DD conditions. The size of active zones vesicles decreased twice in LD, corresponding with times of more intense locomotion activity, but only once in DD conditions.
Assuntos
Ritmo Circadiano/fisiologia , Drosophila melanogaster/fisiologia , Drosophila melanogaster/ultraestrutura , Vesículas Sinápticas/fisiologia , Vesículas Sinápticas/ultraestrutura , Animais , Microscopia Eletrônica de Transmissão , Músculo Esquelético/fisiologia , Músculo Esquelético/ultraestrutura , Junção Neuromuscular/fisiologia , Junção Neuromuscular/ultraestruturaRESUMO
Although recent studies have provided a detailed understanding of cellular interactions occurring during the development of the CNS, little is known about the molecular signals which during the peri and postnatal periods ensure its maturation and functionality. Using the mammalian spinal cord as a model, we have designed experiments to examine the main changes in gene expression occurring during this critical transition. In this paper we describe the cloning and characterization of the rat hypoxia induced gene-1 (Hig-1), its expression pattern during spinal cord maturation and in situ localization of its mRNA. We show an increase in Hig-1 expression between P1 and P15 in the spinal cord and a differential spatial pattern. In the P1 spinal cord we observed preferential expression in regions of dorsal laminae II and III and laminae IX ventrally; while in P8, the distribution was more widespread and overall expression was increased. Hig-1 is also widely expressed in the brain. Results of in situ hybridization experiments, as well as particular features concerning ESTs, led us to propose the expression of an antisense mRNA. Primer-specific RTPCR demonstrates the presence of this aHig-1 transcript whose structure has not yet been characterized. The high homology between putative rHig-1 protein and human- and murine-predicted sequences, as well as its characteristic expression in the Central Nervous System, are indicative of a specific role which could be related to apoptosis signaling during postnatal maturation.
Assuntos
Regulação da Expressão Gênica , Hipóxia/genética , Proteínas de Neoplasias/genética , RNA Antissenso/metabolismo , Medula Espinal/metabolismo , Sequência de Aminoácidos , Animais , Animais Recém-Nascidos , Sequência de Bases , DNA Complementar , Humanos , Hipóxia/metabolismo , Hibridização In Situ , Peptídeos e Proteínas de Sinalização Intracelular , Proteínas Mitocondriais , Dados de Sequência Molecular , Proteínas de Neoplasias/metabolismo , Ratos , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Homologia de Sequência de AminoácidosRESUMO
Embora estejamos prestes a terminar este século, observa-se que a mulher ainda é bastante discriminada e pouca atenção é dada às suas necessidades básicas. Além disso, as leis permanecem insatisfatórias e muitas delas são desrespeitadas impunemente. Uma análise da trajetória da mulher dentro da Medicina é realizad e constata-se que ainda existe discriminação. São analisados também os desafios enfrentados pela mulher médica, assim como os riscos aos quais ele está exposta.