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[
Genes Dev,
2002]
In recent years, it has become apparent that eukaryotic transcriptional repression mechanisms are remarkably varied in their modes of action and effects. Repression can be established by proteins that act over a short range, or at a long distance. Some mechanisms of repression are readily reversible, but others establish a heritable state of long-term silencing...
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Curr Biol,
2005]
Two recent papers on social rearing and olfactory imprinting show that early developmental experiences can lead to long-lasting changes in behaviour of the model nematode Caenorhabditis elegans.
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Ageing Res Rev,
2023]
While aging was traditionally viewed as a stochastic process of damage accumulation, it is now clear that aging is strongly influenced by genetics. The identification and characterization of long-lived genetic mutants in model organisms has provided insights into the genetic pathways and molecular mechanisms involved in extending longevity. Long-lived genetic mutants exhibit activation of multiple stress response pathways leading to enhanced resistance to exogenous stressors. As a result, lifespan exhibits a significant, positive correlation with resistance to stress. Disruption of stress response pathways inhibits lifespan extension in multiple long-lived mutants representing different pathways of lifespan extension and can also reduce the lifespan of wild-type animals. Combined, this suggests that activation of stress response pathways is a key mechanism by which long-lived mutants achieve their extended longevity and that many of these pathways are also required for normal lifespan. These results highlight an important role for stress response pathways in determining the lifespan of an organism.
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Antioxid Redox Signal,
2010]
The free radical theory of aging proposes a causal relationship between reactive oxygen species (ROS) and aging. While it is clear that oxidative damage increases with age, its role in the aging process is uncertain. Testing the free radical theory of aging requires experimentally manipulating ROS production or detoxification and examining the resulting effects on lifespan. In this review, we examine the relationship between ROS and aging in the genetic model organism Caenorhabditis elegans, summarizing experiments using long-lived mutants, mutants with altered mitochondrial function, mutants with decreased antioxidant defenses, worms treated with antioxidant compounds, and worms exposed to different environmental conditions. While there is frequently a negative correlation between oxidative damage and lifespan, there are many examples in which they are uncoupled. Neither is resistance to oxidative stress sufficient for a long life nor are all long-lived mutants more resistant to oxidative stress. Similarly, sensitivity to oxidative stress does not necessarily shorten lifespan and is in fact compatible with long life. Overall, the data in C. elegans indicate that oxidative damage can be dissociated from aging in experimental situations.
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Aging Cell,
2002]
Much of the recent interest in aging research is due to the discovery of genes in a variety of model organisms that appear to modulate aging. A large amount of research has focused on the use of such long-lived mutants to examine the fundamental causes of aging. While model organisms do offer many advantages for studying aging, it also critical to consider the limitations of these systems. In particular, ectothermic (poikilothermic) organisms can tolerate a much larger metabolic depression than humans. Thus, considering only chronological longevity when assaying for long-lived mutants provides a limited perspective on the mechanisms by which longevity is increased. In order to provide true insight into the aging process additional physiological processes, such as metabolic rate, must also be assayed. This is especially true in the nematode Caenorhabditis elegans, which can naturally enter into a metabolically reduced state in which it survives many times longer than its usual lifetime. Currently it is seen as controversial if long-lived C. elegans mutants retain normal metabolic function. Resolving this issue requires accurately measuring the metabolic rate of C. elegans under conditions that minimize environmental stress. Additionally, the relatively small size of C. elegans requires the use of sensitive methodologies when determining metabolic rates. Several studies indicating that long-lived C. elegans mutants have normal metabolic rates may be flawed due to the use of inappropriate measurement conditions and techniques. Comparisons of metabolic rate between long-lived and wild-type C. elegans under more optimized conditions indicate that the extended longevity of at least some long-lived C. elegans mutants may be due to a reduction in metabolic rate, rather than an alteration of a
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New York Times,
1996]
Mutant worms that live five times as long as their normal counterparts are yielding clues to the genetic control of life span-and lending new credence to the old idea that one way to live longer might be to live less.
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Curr Biol,
2007]
It has long been appreciated that the oocyte cortex plays a key role in regulating fertilization and establishing embryonic polarity. Recent studies have identifed the anti-phosphatase EGG-3 as a cortical anchor for regulatory proteins required for launching embryogenesis in Caenhorhabditis elegans.
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Learn Mem,
2001]
Although the nonassociative form of learning, habituation, is often described as the simplest form of learning, remarkably little is known about the cellular processes underlying its behavioral expression. Here, we review research on habituation in the nematode Caenorhabditis elegans that addresses habituation at behavioral, neural circuit, and genetic levels. This work highlights the need to understand the dynamics of a behavior before attempting to determine its underlying mechanism. In many cases knowing the characteristics of a behavior can direct or guide a search for underlying cellular mechanisms. We have highlighted the importance of interstimulus interval (ISI) in both short- and long-term habituation and suggested that different cellular mechanisms might underlie habituation at different ISIs. Like other organisms, C. elegans shows both accumulation of habituation with repeated training blocks and long-term retention of spaced or distributed training, but not for massed training. Exposure to heat shock during the interblock intervals eliminates the long-term memory for habituation but not the accumulation of short-term habituation over blocks of training. Analyses using laser ablation of identified neurons, and of identified mutants have shown that there are multiple sites of plasticity for the response and that glutamate plays a role in long-term retention habituation training.
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Neurosci Bull,
2008]
Model invertebrate organism Caenorhabditis elegans has become an ideal model to unravel the complex processes of memory. C. elegans has three simple forms of memory: memory for thermosensation, memory for chemosensation, and memory for mechanosensation. In the form of memory for mechanosensation, short-term memory, intermediate-term memory, and long-term memory have been extensively studied. The short-term memory and intermediate-term memory may occur in the presynaptic sensory neurons, whereas the long-term memory may occur in the postsynaptic interneurons. This review will discuss the recent progress on genetic and molecular regulation of memory in C. elegans.
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Behav Cogn Neurosci Rev,
2003]
Studies on the cellular basis of learning and memory have revealed several distinct phases of memory that can be distinguished by their time course. In addition to the traditional short-term and long-term memory distinction, several other phases of memory have been identified: forms of intermediate-term memory, at least two seperable forms of long-term memory, and possibly several forms of short-term memory. This article presents the contributions made by research on phases of memory for habituation in the nematode Caenorhabditis elegans. Through behavioral, neural circuit and genetic analyses of habituation, research using this simple organism has provided insights into different memory phases. Studying experience-dependent plasticity of this behavior has not only provided corroborating evidence for the existence of short-, intermediate-, and long-term forms of memory, as have been demonstrated in both Aplysia and Drosophila, but also has revealed the possible existence of multiple forms of short-term memory.