Browsing by Author "Rios, M."

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    A Trypsin-Like Enzyme Is Present in the Sperm of the Shrimp Rhynchocin Typus
    (1997) Rios, M.; Barros Rodríguez, Fernando Claudio
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    Genital sensory stimulation shifts estradiol intraoviductal signaling from nongenomic to genomic pathways, independently from prolactin surges
    (SOC BIOLGIA CHILE, 2007) Penarroja Matutano, C.; Parada Bustamante, A.; Orihuela, P. A.; Rios, M.; Velasquez, Luis A.; Croxatto, H. B.
    Estradiol (132) accelerates oviductal egg transport through nongenomic pathways involving oviductal protein phosphorylation in non-mated rats, and through genomic pathways in mated rats. Here we investigated the ability of cervico-vaginal stimulation (CVS) to switch the mode of action of E 2 in the absence of other male-associated components. Pro-estrous rats were subjected to CVS with a glass rod and 12 hours later were injected subcutaneously with E 2 and intrabursally with the RNA synthesis inhibitor Actinomycin D or the protein phosphorylation inhibitor H-89. The number of eggs in the oviduct, assessed 24 It later, showed that Actinomycin D, but not H-89 blocked the E-2-induced egg transport acceleration. This clearly indicates that CVS alone, without other mating-associated signals, is able to shift E 2 signaling from nongenomic to genomic pathways. Since mating and CVS activate a neuroendocrine reflex that causes iterative prolactin (PRL) surges, the involvement of PRL pathway in this phenomenon was evaluated. Prolactin receptor mRNA and protein expression in the rat oviduct was demonstrated by RT-PCR and Western blot, but their levels were not different on day 2 of the cycle (C2) or pregnancy (P2). Activated STAT 5a/b (phosphorylated) was detected by Western blot on P2 in the ovary, but not in the oviduct, showing that mating does not stimulate this PRL signalling pathway in the oviduct. Other rats subjected to CVS in the evening of pro-estrus were treated with bromoergocriptine to suppress PRL surges. In these rats, H-89 did not block the E-2-induced acceleration of egg transport suggesting that PRL surges are not essential to shift E-2 signaling pathways in the oviduct. We conclude that CVS is one of the components of mating that shifts E-2 signaling in the oviduct from nongenomic to genomic pathways, and this effect is independent of PRL surges elicited by mating.
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    Ladybird (Coleoptera : Coccinellidae) dispersal in experimental fragmented alfalfa landscapes
    (CZECH ACAD SCI, INST ENTOMOLOGY, 2005) Grez, A.A.; Zaviezo, T.; Rios, M.
    Habitat fragmentation may affect the dispersal behaviour of individuals across the landscape. If there is a high boundary contrast between the remaining fragments and the matrix, individuals should tend to stay inside the fragments, but the configuration of the landscape, i.e. the level of fragmentation and isolation distance between fragments, may modulate this. To test these ideas, we made several mark-recapture experiments with the ladybird Eriopis connexa (Germ.) in manipulated alfalfa model landscapes (30 x 30 m). Specifically we evaluated (i) ladybird movement and permanence in alfalfa and bare ground areas, (ii) how they move across fragment/matrix boundaries, (iii) how their movement between fragments within a landscape is affected by fragmentation level and isolation distance, and (iv) how their permanence in the landscape is affected by fragmentation Ievel and isolation distance. The fragmented alfalfa landscapes had a constant level of habitat loss (84%), but varied in the level of habitat fragmentation (4 or 16 fragments), and isolation distance between fragments (2 or 6 m). We also sampled aphid abundance in the different landscapes through time. We found that ladybirds stay longer and displace less in alfalfa than on bare ground, and that they move less from the alfalfa fragments to the neighbouring bare ground matrix than vice versa. At the landscape level, ladybirds had a higher inter-fragment movement when fragments were closer, they tended to remain in less fragmented landscapes, regardless of their isolation distance. Aphid abundance increased in time, but it was similar in all landscapes. Ladybird movement within fragments, in the matrix and in the boundary between both habitats explains why ladybirds concentrate within alfalfa fragments. However, their dispersal movements at the landscape level do not reflect the higher abundance sometimes found for several species of ladybirds in more fragmented landscapes. At this larger scale, other mechanisms may have a stronger influence in determining the abundance of ladybirds.
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    Low physiological levels of prostaglandins E-2 and F-2 improve human sperm functions
    (2016) Rios, M.; Carreño Bustos, Daniela Verónica; Oses, Carolina; Barrera Rojas, Nelson Patricio; Kerr, B.; Villalón, Manuel J.
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    PoQBA: A new path admission control for diffserv networks
    (2007) Pena, E.; Rios, M.; Oberli, C.; Marianov Kluge, Vladimir