Browsing by Subject "Nothobranchius"

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    Circadian activity rhythms during the last days of Nothobranchius rachovii’s life: A descriptive model of circadian system breakdown
    (Informa Healthcare USA, Inc., 2014-11-25) Lucas-Sánchez, Alejandro; Martínez-Nicolás, Antonio; Madrid, Juan Antonio; Almaida Pagán, Pedro Francisco; Mendiola, Pilar; Costa, Jorge de; Fisiología
    Several studies have been performed to identify age-related changes in the circadian system (CS) but the impairment of the CS and its chronodisruption at the end of an organism life have not been studied in depth. Aging commonly affects the input pathways into the biological clock or restraints their processing, therefore simplifying the system output, the overt rhythms. The purpose of this work was to do a complete characterization of changes that occurs in the CS in the last stage of a vertebrate organism life and to develop tools able to detect in which moment of the last days of life is the animal, using an overt rhythm, the rest-activity rhythm (RAR). For that, a fish species proposed as model for aging studies, Nothobranchius rachovii, has been used. A progressive and sequential CS breakdown has been described for the last 22 d of life of N. rachovii ( 7% of total life), suffering a general RAR impairment mainly reflected by changes in phase regularity, complexity, amplitude and the ability to stay synchronized to the LD cycle. Also, an equation of days remaining of life, based on the RAR description, has been calculated and proposed as a tool to identify close-to-death individuals which could be subjected to an adequate restoring treatment to enhance the CS function and improve their well-being.
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    Impact of a shift work-like lighting schedule on the functioning of the circadian system in the short-lived fish Nothobranchius furzeri
    (Elsevier, 2018-09-02) Almaida Pagán, Pedro Francisco; Ortega-Sabater, C.; Lucas-Sánchez, A.; Martinez-Nicolas, A.; Espinosa, C.; Madrid, J. A.; Rol, M.; Mendiola, P.; Costa, J. de; Esteban Abad, María de los Ángeles; Fisiología
    Adult Nothobranchius furzeri of the MZM-04/10 strain were individually kept and subjected to a “5+2” shifting lighting schedule (SHIFT) for 8 weeks in order to evaluate the desynchronizing effects of a simulated human-like shift-work schedule on the functioning of the circadian system (CS). With this aim, sixteen 21-week-old N. furzeri were placed into a Morning, Night and Evening schedule (lights on from 08:00 to 16:00, 00:00 to 08:00 and 16:00 to 00:00 h, respectively) and fed once a day in the middle of the corresponding photophase (12:00, 04:00 and 20:00 h, respectively). Then, in the weekends (2 days), fish were always returned to the Morning shift. As controls, 16 fish were maintained under a non-shifting LD cycle condition (CONTROL) throughout the whole experiment, with lights on from 08:00 to 16:00 h. Rest-activity rhythm (RAR) of fish subjected to SHIFT showed several symptoms of chronodisruption, such as a decrease in the percentage of diurnal activity and a reduction of the relative amplitude and the circadian function index with time. When a periodogram analysis was performed, RAR of N. furzeri under SHIFT conditions showed up to three separate circadian components: one longer than 24 h (26.5 h) that followed the weekly 8 h delays; a short-period component (~23 h) that was related to the weekend's phase advances, and finally, a 24 h component. The shifting LD schedule also affected fish CS at a molecular level, with several significant differences in the expression of core genes of the molecular clock (bmal1, clock, rorα, rev-erbα) between SHIFT and CONTROL animals. RAR impairment along with changes in clock gene expression could be associated with high stress and accelerated aging in these fish.
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    Nothobranchius as a model for aging studies. A review
    (ISOAD, 2014-08) Lucas-Sánchez, Alejandro; Almaida Pagán, Pedro Francisco; Mendiola, Pilar; Costa, Jorge de; Fisiología
    In recent decades, the increase in human longevity has made it increasingly important to expand our knowledge on aging. To accomplish this, the use of animal models is essential, with the most common being mouse (phylogenetically similar to humans, and a model with a long life expectancy) and Caenorhabditis elegans (an invertebrate with a short life span, but quite removed from us in evolutionary terms). However, some sort of model is needed to bridge the differences between those mentioned above, achieving a balance between phylogenetic distance and life span. Fish of the genus Nothobranchius were suggested 10 years ago as a possible alternative for the study of the aging process. In the meantime, numerous studies have been conducted at different levels: behavioral (including the study of the rest-activity rhythm), populational, histochemical, biochemical and genetic, among others, with very positive results. This review compiles what we know about Nothobranchius to date, and examines its future prospects as a true alternative to the classic models for studies on aging.
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    Rest-activity circadian rhythms in aged Nothobranchius korthausae. The effects of melatonin
    (Elsevier, 2013-03-04) Lucas-Sánchez, Alejandro; Almaida Pagán, Pedro Francisco; Martínez-Nicolás, Antonio; Madrid, Juan Antonio; Mendiola, Pilar; Costa, Jorge de; Fisiología
    Adult (48-week-old) and senescent (72-week-old) individually-kept Nothobranchius korthausae were used as experimental subjects to characterise circadian system (CS) function and age-related changes in enescent fish. This species was specifically chosen because it has already shown potential for use as a model system in gerontological studies. The rest-activity rhythm (RAR) in fish can be easily monitored and used to characterise the state of the CS, and it has also been proposed as a reliable model to study sleep-like periods in fish. As they aged, N. korthausae experienced a significant decrease in total daily activity and a progressive impairment of the RAR, accompanied by changes in the regularity, fragmentation and amplitude of the rhythm. The ability of the CS to oscillate autonomouslywhen the twomain synchronizers, photoperiod and feeding time,were absent (continuous darkness and randomfeeding), was also impaired with age, as the capacity to re-synchronise to the light–dark (LD) cycle declined. Melatonin treatment improved the regularity, fragmentation and amplitude of the RAR in senescent fish, and it also improved sleep efficiency. In conclusion,N. korthausae represents a viablemodel for studying the aging of the circadian system and the restorative effect of chronobiotic substances, such as melatonin.