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de Leon I.P.,Institute Investigaciones Biologicas Clemente Estable
International Journal of Molecular Sciences | Year: 2013

During evolution, plants have developed mechanisms to cope with and adapt to different types of stress, including microbial infection. Once the stress is sensed, signaling pathways are activated, leading to the induced expression of genes with different roles in defense. Mosses (Bryophytes) are non-vascular plants that diverged from flowering plants more than 450 million years ago, allowing comparative studies of the evolution of defense-related genes and defensive metabolites produced after microbial infection. The ancestral position among land plants, the sequenced genome and the feasibility of generating targeted knock-out mutants by homologous recombination has made the moss Physcomitrella patens an attractive model to perform functional studies of plant genes involved in stress responses. This paper reviews the current knowledge of inducible defense mechanisms in P. patens and compares them to those activated in flowering plants after pathogen assault, including the reinforcement of the cell wall, ROS production, programmed cell death, activation of defense genes and synthesis of secondary metabolites and defense hormones. The knowledge generated in P. patens together with comparative studies in flowering plants will help to identify key components in plant defense responses and to design novel strategies to enhance resistance to biotic stress. © 2013 by the authors; licensee MDPI, Basel, Switzerland.


Caputi A.A.,Institute Investigaciones Biologicas Clemente Estable
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2012

This article introduces a bio-inspired neural network that uses timing for streaming self-generated signals. Timing messages in a crowded informatics space is a well-known method for collision avoidance (i.e. 802.11 protocol). Recently, Nogueira and Caputi (2011) have shown that timing the emission of a sensory carrier allows electric fish to stream self-generated signals through a refractoriness window in the presence of interference. Here I model the system and show that a simple sensory-motor feedback loop is enough for adapting the timing of the pacemaker controlling the emission of the carrier. Critical aspects of this behavior are the shape of the refractoriness window and the duration of signals effects on the motor command. © 2012 Springer-Verlag.


Stanley E.,Institute Investigaciones Biologicas Clemente Estable
Journal of Arachnology | Year: 2011

I describe oviposition sites and egg-hiding for four species of the family Gonyleptidae: Parampheres bimaculatus, Parampheres ronae (Gonyleptinae), Discocyrtus prospicuus, and Pachyloides thorellii (Pachylinae). Females of P. bimaculatus bury single eggs on the ground; the first record of this behavior among gonyleptids. Females of the other three species lay their eggs, singly or in clusters, on tree trunks or rock fissures. I found the eggs of P. ronae and D. prospicuus covered with debris, whereas eggs of P. thorellii were not. Females of D. prospicuus and P. thorellii lay their eggs over an extended period of time. At least for hemipterans, covering the eggs with debris works as a way to camouflage or prevent egg dehydration. I hypothesize that for the species used in this study, to spread isolated eggs in time and space may also protect them against predators and parasites. © 2011 The American Arachnological Society.


Monica Brauer M.,Institute Investigaciones Biologicas Clemente Estable | Smith P.G.,University of Kansas Medical Center
Autonomic Neuroscience: Basic and Clinical | Year: 2015

The female reproductive tract undergoes remarkable functional and structural changes associated with cycling, conception and pregnancy, and it is likely advantageous to both individual and species to alter relationships between reproductive tissues and innervation. For several decades, it has been appreciated that the mammalian uterus undergoes massive sympathetic axon depletion in late pregnancy, possibly representing an adaptation to promote smooth muscle quiescence and sustained blood flow. Innervation to other structures such as cervix and vagina also undergo pregnancy-related changes in innervation that may facilitate parturition. These tissues provide highly tractable models for examining cellular and molecular mechanisms underlying peripheral nervous system plasticity. Studies show that estrogen elicits rapid degeneration of sympathetic terminal axons in myometrium, which regenerate under low-estrogen conditions. Degeneration is mediated by the target tissue: under estrogen's influence, the myometrium produces proteins repulsive to sympathetic axons including BDNF, neurotrimin, semaphorins, and pro-NGF, and extracellular matrix components are remodeled. Interestingly, nerve depletion does not involve diminished levels of classical sympathetic neurotrophins that promote axon growth. Estrogen also affects sympathetic neuron neurotrophin receptor expression in ways that appear to favor pro-degenerative effects of the target tissue. In contrast to the uterus, estrogen depletes vaginal autonomic and nociceptive axons, with the latter driven in part by estrogen-induced suppression of BMP4 synthesis. These findings illustrate that hormonally mediated physiological plasticity is a highly complex phenomenon involving multiple, predominantly repulsive target-derived factors acting in concert to achieve rapid and selective reductions in innervation. © 2014 Elsevier B.V.


Albo M.J.,Institute Investigaciones Biologicas Clemente Estable | Costa F.G.,Institute Investigaciones Biologicas Clemente Estable
Animal Behaviour | Year: 2010

The occurrence of nuptial gifts is rare in spiders, being well known only for a single species, Pisaura mirabilis (Pisauridae), whose males offer females a prey wrapped in silk during courtship. Although some males can mate without offering a prey, the gift in this species is thought to represent male mating effort. Male gift offering has been recently described in Paratrechalea ornata, a Neotropical spider belonging to another family, Trechaleidae. We investigated the function of the gift in this species by testing the mating effort hypothesis and two other nonexclusive hypotheses, sexual cannibalism avoidance and paternal investment. Two groups of males were exposed to virgin females: 23 males with no prey (NP group) and 21 males carrying a prey (CP group). Mating success, courtship, copulation and first oviposition were recorded. Males from group CP had better mating success, longer copulations and longer palpal insertions than those from NP. Longer copulations were associated with earlier eggsac construction and oviposition. Some unmated males from NP wrapped prey carrion when they returned to their breeding jars after the trial. Our findings suggest that nuptial gift giving represents male mating effort for P. ornata. Nuptial gifts would allow males to control copulation duration and to accelerate female oviposition, improving sperm supply and paternity, and minimizing possible costs of remating with polyandrous females. © 2010 The Association for the Study of Animal Behaviour.


Baruffaldi L.,Institute Investigaciones Biologicas Clemente Estable | Costa F.G.,Institute Investigaciones Biologicas Clemente Estable
Journal of Ethology | Year: 2010

Male wolf spiders are capable of recognising sexual signals associated with female silk threads. In the wolf spider Schizocosa malitiosa variations in female receptivity have been studied, but changes in female silk attractiveness remain unknown. We analysed the sexual responses of adult males (leg shaking, papal drumming and searching) exposed to silk cues from subadult, virgin and mated females of different ages, and females that were or were not carrying an egg-sac. Penultimate and recently moulted adult females elicited low levels of male sexual behaviour, while those of virgin females (21-40 days old) were the most attractive. Silk threads slowly became less attractive after mating. Cues from females carrying an egg-sac as well as females in the inter egg-sac period were fairly attractive. The low attractiveness of recently moulted females disagrees with their high sexual receptivity. In contrast, females continued to elicit strong male responses during a 10-day period after mating, despite the fact that they immediately become sexually reluctant, suggesting strong selection for male searching ability. Low attractiveness during the egg-carrying period could reflect the fact that females do not require any further sperm. Concordances and discordances between attractiveness and sexual receptivity suggest that they respond to different physiological mechanisms. © Japan Ethological Society and Springer 2009.


Aisenberg A.,Institute Investigaciones Biologicas Clemente Estable | Barrantes G.,University of Costa Rica
Naturwissenschaften | Year: 2011

Unpublished field observations in Leucauge argyra, a tropical orb weaver spider, suggest the occurrence of conspicuous mating plugs that could reduce or prevent remating attempts. Otherwise, the sexual behavior of this species remains unknown. The aims of this study were to describe the courtship behavior and copulation in L. argyra and investigate mating plug formation in this species. Fourteen virgin females and 12 plugged females were exposed to up to three males and checked for mating plug formation. Of the 12 virgins that copulated, nine produced plugs (five immediately after copulation), and the five plugged females that copulated produced another mating plug immediately after copulation. We did not detect the transfer of any male substance during copulation but observed a whitish liquid emerging from female genital ducts. Plug formation was positively associated with male twanging during courtship. One virgin and four plugged females cannibalized males. In seven trials with virgins and in three trials with plugged females, the male's palp adhered to a substance that emerged from female genital ducts and spread on her genital plate. The male had to struggle energetically to free his glued palp; two of these males were cannibalized while trying to release their palps. Females seem to determine copulation duration by altering the timing of mating plug formation and through sexual cannibalism. This is the first case reported of a mating plug as a sticky trap for males. © Springer-Verlag 2011.


Iribarne L.,Institute Investigaciones Biologicas Clemente Estable | Castello M.E.,Institute Investigaciones Biologicas Clemente Estable
Journal of Physiology Paris | Year: 2014

Teleosts are a numerous and diverse group of fish showing great variation in body shape, ecological niches and behaviors, and a correspondent diversity in brain morphology, usually associated with their functional specialization. Weakly electric fish are a paradigmatic example of functional specialization, as these teleosts use self-generated electric fields to sense the nearby environment and communicate with conspecifics, enabling fish to better exploit particular ecological niches.We analyzed the development of the brain of the pulse type gymnotid Gymnotus omarorum, focusing on the brain regions involved directly or indirectly in electrosensory information processing. A morphometric analysis has been made of the whole brain and of brain regions of interest, based on volumetric data obtained from 3-D reconstructions to study the growth of the whole brain and the relative growth of brain regions, from late larvae to adulthood. In the smallest studied larvae some components of the electrosensory pathway appeared to be already organized and functional, as evidenced by tract-tracing and in vivo field potential recordings of electrosensory-evoked activity. From late larval to adult stages, rombencephalic brain regions (cerebellum and electrosensory lateral line lobe) showed a positive allometric growth, mesencephalic brain regions showed a negative allometric growth, and the telencephalon showed an isometric growth. In a first step towards elucidating the role of cell proliferation in the relative growth of the analyzed brain regions, we also studied the spatial distribution of proliferation zones by means of pulse type BrdU labeling revealed by immunohistochemistry. The brain of G. omarorum late larvae showed a widespread distribution of proliferating zones, most of which were located at the ventricular-cisternal lining. Interestingly, we also found extra ventricular-cisternal proliferation zones at in the rombencephalic cerebellum and electrosensory lateral line lobe. We discuss the role of extraventricular-cisternal proliferation in the relative growth of the latter brain regions. © 2014 Elsevier Ltd.


Toscano-Gadea C.A.,Institute Investigaciones Biologicas Clemente Estable
Journal of Arachnology | Year: 2010

This paper describes the sexual behavior of Bothriurus buecherli San Martn 1963 and compares it with the rest of the B. prospicuus group. The mating behavior was very similar to other species of the group, but B. buecherli presented some differences in the initial stages, one being a long period of inactivity after the male grasps the female pedipalps. Information presented includes reference to the sexual sting, post-partum copulation, and an analysis of a case of cannibalism by the female. © 2010 The American Arachnological Society.


Grant
Agency: European Commission | Branch: FP7 | Program: MC-IIFR | Phase: PEOPLE-2007-4-2.IIF | Award Amount: 15.00K | Year: 2010

The knowledge on regulatory roles of epigenetic mechanisms (heritable changes in the genome function without a change in the DNA sequence) has grown very fast during the last decade since they can be the target for treating several pathologies related to cancer and neurodegeneration. In the base of these diseases deficiencies in DNA repair mechanisms have also been found. In this respect, two human syndromes (Xeroderma Pigmentosum and Cockaynes Syndrome) affecting one of the major DNA repair systems in human cells called nucleotide excision repair (NER) characterized by sensitivity to UV irradiation, are interesting models to unravel the link between chromatin remodeling processes and DNA repair. Expected results on the possible influence of chromatin remodeling processes on the higher sensitivity to UV radiation of Cockaynes Syndrome cells will allow further investigations in order to understand how these mechanisms are involved in the development of cancer and/or neurodegeneration found in these patients. Since the proposed investigation requires a multidisciplinary study (cytogenetics, molecular biology and immunocytochemistry), it is of the utmost importance not only for the planned research activity at the Laboratory of Prof. Palitti (since this line of research fits very well with the purposes already established by the Network of Excellence - NoE Epigenetic Network created by several laboratories from Europe and supported by the FP6 Program from the European Community) but also for having the possibility to incorporate new methodologies and strategies to continue with the study of possible links between epigenetic and DNA repair in our laboratory in Uruguay with the aim to initiate studies on epigenetic therapy mainly applied to facilitate chemotherapy treatment of cancer diseases.

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