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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.

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Unpublished field observations in Leucauge argyra, a tropical orb weaver spider, suggest the occurrence of conspicuous mating plugs that could reduce or prevent remating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.

Kruk C.,Institute Investigaciones Biologicas Clemente Estable | Kruk C.,University of the Republic of Uruguay | Segura A.M.,University of the Republic of Uruguay
Hydrobiologia | Year: 2012

The identification of the main factors driving phytoplankton community structure is essential to understand and adequately manage freshwater ecosystems. We hypothesize that differences in morphological traits reflect phytoplankton functional properties that will be selected under particular environmental conditions, namely their habitat template. We apply a morphology-based functional groups (MBFG) approach to classify phytoplankton organisms and define each group template. We use machine learning techniques to classify a large number of phytoplankton communities and environmental variables from different climate zones and continents. Random forest analysis explained well the distribution of most groups' biovolume and the selected variables reflected ecological preferences according to morphology. By means of a classification tree it was also possible to identify thresholds of the environmental variables promoting groups dominance in different lakes. For example group III (filaments with aerotopes and high surface/volume including potentially toxic species) was dominant when light attenuation coefficient was >3. 9 m -1 and total nitrogen was >2,800 μg l -1. We demonstrate that morphology captures ecological preferences of phytoplankton groups and provides empirical values to describe their habitat template. © 2012 Springer Science+Business Media B.V.

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.

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