1,721,028 research outputs found
Un ingranaggio per due orologi
No full textI risultati delle nostre ricerche collegano, per la prima volta, una proteina che svolge un ruolo cardinale nell’orologio biologico circadiano di un organismo ad un comportamento che costituisce una risposta a variazioni ambientali corrispondenti al ciclo delle stagioni. Nel loro insieme questi risultati costituiscono anche un nuovo, solido argomento a sostegno della teoria neo-darwiniana dell’evoluzione, una testimonianza concreta del come la struttura genetica di una specie possa evolvere in natura per effetto della mutazione spontanea e della selezione naturale
A concise overview of circadian timing in Drosophila
No full textThe molecular aspects of circadian rhythmicity in Drosophila melanogaster are reviewed, with particular regard to the core of the master oscillator and the light signalling input pathway. The core is schematically represented as consisting of two interlocking transcriptional feedback loops based principally on the clock genes period, timeless, clock and cycle and their products which, through the interaction with other partners, give rise to a stable 24h endogenous oscillator. Light signalling to the clock is multifaceted and is still the subject of much speculation and research. Here we review data essentially regarding the role of the clock protein Timeless and its interaction with the photopigment Cryptochrome
Cytogenetic and immunofluorescence analysis of benzo[a]pyrene-DNA adduct formation and chromosome damage in larval brain neuroblasts of Drosophila melanogaster.
No full textRecently we have evaluated the relationship between benzo[a]-pyrene(BaP)-DNA adducts, determined by 32P-postlabelling, and clone frequencies in the somatic mutation and recombination test (SMART) in Drosophila melanogaster. Following that study we proceeded to characterise further the mechanism of induction of genetic damage in vivo by BaP in Drosophila by cytogenetic analysis of larval brain neuroblasts. Third stage larvae were treated with 4 and 10 mM BaP for 24, 48 or 72 h. In all cases, the larvae were killed 72 h after the beginning of treatment, entailing 48, 24 or 0 h post-treatment recovery in BaP-free medium, respectively. At the end of the treatment the following data were collected: (i) the types and levels of chromosome aberrations in neuroblast metaphase and anaphase nuclei; (ii) the distribution and level of BaP-DNA adducts, revealed by indirect immunofluorescence in neuroblast nuclei using an anti-(BaP-DNA) antibody. The results indicate that BaP induces chromosome breaks, deletions and exchanges in this system. In particular, chromosome exchanges decrease as the post-treatment recovery time increases, and the dynamics of breaks and deletions appear to be inversely related to those of the exchanges. This suggests that exchanges may require few preconditions to occur and are thus expressed soon after treatment. Chromosome breaks and deletions could require multiple single events before the actual damage is expressed (even some cell divisions away from the end of treatment). The immunofluorescence analysis suggests that BaP-DNA adducts are more abundant in the heterochromatin of the neuroblast nuclei
The role of micro RNAs in post transcriptional regulation of the circadian clock machinery in Drosophila melanogaster
No full textMolecular and Physiological Determinants of Amyotrophic Lateral Sclerosis: What the DJ-1 Protein Teaches Us
Full text linkAmyotrophic lateral sclerosis (ALS) is an adult-onset disease which causes the progressive degeneration of cortical and spinal motoneurons, leading to death a few years after the first symptom onset. ALS is mainly a sporadic disorder, and its causative mechanisms are mostly unclear. About 5–10% of cases have a genetic inheritance, and the study of ALS-associated genes has been fundamental in defining the pathological pathways likely also involved in the sporadic forms of the disease. Mutations affecting the DJ-1 gene appear to explain a subset of familial ALS forms. DJ-1 is involved in multiple molecular mechanisms, acting primarily as a protective agent against oxidative stress. Here, we focus on the involvement of DJ-1 in interconnected cellular functions related to mitochondrial homeostasis, reactive oxygen species (ROS) levels, energy metabolism, and hypoxia response, in both physiological and pathological conditions. We discuss the possibility that impairments in one of these pathways may affect the others, contributing to a pathological background in which additional environmental or genetic factors may act in favor of the onset and/or progression of ALS. These pathways may represent potential therapeutic targets to reduce the likelihood of developing ALS and/or slow disease progression
Rhythm and Mood: Relationships Between the Circadian Clock and Mood-Related Behavior.
No full textMood disorders are multifactorial and heterogeneous diseases caused by the interplay of several genetic and environmental factors. In humans, mood disorders are often accompanied by abnormalities in the organization of the circadian system, which normally synchronizes activities and functions of cells and tissues. Studies on animal models suggest that the basic circadian clock mechanism, which runs in essentially all cells, is implicated in the modulation of biological phenomena regulating affective behaviors. In particular, recent findings highlight the importance of the circadian clock mechanisms in neurological pathways involved in mood, such as monoaminergic neurotransmission, hypothalamus-pituitary-adrenal axis regulation, suprachiasmatic nucleus and olfactory bulb activities, and neurogenesis. Defects at the level of both, the circadian clock mechanism and system, may contribute to the etiology of mood disorders. Modification of the circadian system using chronotherapy appears to be an effective treatment for mood disorders. Additionally, understanding the role of circadian clock mechanisms, which affect the regulation of different mood pathways, will open up the possibility for targeted pharmacological treatments. (PsycINFO Database Record (c) 2014 APA, all rights reserved
Circadian Clock Dysfunction and Psychiatric Disease: Could Fruit Flies have a Say?
Full text linkThere is evidence of a link between the circadian system and psychiatric diseases. Studies
in humans and mammals suggest that environmental and/or genetic disruption of the circadian
system leads to an increased liability to psychiatric disease. Disruption of clock genes
and/or the clock network might be related to the etiology of these pathologies; also, some
genes, known for their circadian clock functions, might be associated to mental illnesses
through clock-independent pleiotropy. Here, we examine the features which we believe
make Drosophila melanogaster a model apt to study the role of the circadian clock in psychiatric
disease. Despite differences in the organization of the clock system, the molecular
architecture of the Drosophila and mammalian circadian oscillators are comparable and
many components are evolutionarily related. In addition, Drosophila has a rather complex
nervous system, which shares much at the cell and neurobiological level with humans,
i.e., a tripartite brain, the main neurotransmitter systems, and behavioral traits: circadian
behavior, learning and memory, motivation, addiction, social behavior. There is evidence
that the Drosophila brain shares some homologies with the vertebrate cerebellum, basal
ganglia, and hypothalamus-pituitary-adrenal axis, the dysfunctions of which have been tied
to mental illness.We discuss Drosophila in comparison to mammals with reference to the:
organization of the brain and neurotransmitter systems; architecture of the circadian clock;
clock-controlled behaviors.We sum up current knowledge on behavioral endophenotypes,
which are amenable to modeling in flies, such as defects involving sleep, cognition, or
social interactions, and discuss the relationship of the circadian system to these traits.
Finally, we consider if Drosophila could be a valuable asset to understand the relationship
between circadian clock malfunction and psychiatric disease
Evolution of behavioral genes
No full textBehavioral genetics has come a long way since it started to be taken semi-seriously in the 1950s. In the early days, selection experiments and studies of highly inbred strains tended to provide the major experimental approaches. These had a distinctly evolutionary flavor in that crosses between selected or inbred lines would be used to determine the “genetic architecture” of a phenotype, and to provide some indirect evidence for the selective forces underlying the trait in question, be it sexual behavior in flies or aggression in mice (Hay 1985). In the 1970s, Seymour Benzer advocated the “neurogenetic” approach with its emphasis on single genes, and which used behavior as an entrée into the dissection of the nervous system of the fruit fly, Drosophila melanogaster (Benzer 1971). With the coming of the molecular era in the 1980s, the cloning and sequencing of these “behavioral” genes, allied to the transgenic technology mediated by P-elements, added a further spectacular dimension to fly neurogenetics. This has been further exploited by the use of the Gal4/UAS misexpression systems that can be targeted to specific neurons (Brand and Perrimon 1993). Thus, the “brain to behavior” pathway in the fly can now be analyzed at almost all biological levels, from DNA through biochemistry, cellular biology, anatomy, and physiology. However, similar technical developments in mice and worms mean that these types of sophisticated manipulations can be extended to vertebrates and nematodes
Comparative analysis of circadian clock genes in insects
Full text linkAfter a slow start, the comparative analysis of clock genes in insects has developed into a mature area of study in recent years. Brain transplant or surgical interventions in larger insects defined much of the early work in this area, before the cloning of clock genes became possible. We discuss the evolution of clock genes, their key sequence differences, and their likely modes of regulation in several different insect orders. We also present their expression patterns in the brain, focusing particularly on Diptera, Lepidoptera, and Orthoptera, the most common non-genetic model insects studied. We also highlight the adaptive involvement of clock molecules in other complex phenotypes which require biological timing, such as social behaviour, diapause and migration
Clines in clock genes: fine-tuning circadian rhythms to the environment
No full textThe dissection of the circadian clock into its molecular components represents the most striking and well-studied example of a gene regulatory network underlying a complex behavioural trait. By contrast, the evolutionary analysis of the clock has developed more slowly. Here we review studies that have surveyed intraspecific clock gene variation over large geographical areas and have discovered latitudinal clines in gene frequencies. Such spatial patterns traditionally suggest that natural selection shapes genetic variation, but it is equally possible that population history, or a mixture of demography and selection, could contribute to the clines. We discuss how population genetics, together with functional assays, can illuminate these possible cases of natural selection in Drosophila clock genes
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