The Experts below are selected from a list of 639 Experts worldwide ranked by ideXlab platform
J. Ortega-escobar - One of the best experts on this subject based on the ideXlab platform.
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Visual odometry in the wolf spider Lycosa tarantula (Araneae: Lycosidae)
Journal of Experimental Biology, 2014Co-Authors: J. Ortega-escobar, M A RuizAbstract:The wolf spider Lycosa tarantula homes using path integration. The angular component of the displacement is measured using a polarized-light compass associated with the functioning of the anterior median eyes. However, how L. tarantula estimates the linear component of the displacement was not known prior to this investigation. The ability of L. tarantula to gauge the distance walked after being displaced from its burrow was investigated using experimental channels placed in an indoor setup. Firstly, we manipulated the perception of visual stimuli by covering all the spider's eyes. Secondly, we changed the optic flow supplied by a black-and-white grating (λ=2 cm) perceived either in the lateral or in the ventral field of view. Finally, the period of the lateral or ventral grating was changed from λ=2 cm to λ=1 cm. Our results indicate that visual information contributes to distance estimation because when the spider's eyes were covered, the spiders tended to search for the burrow at very variable distances. This visual information is created by the motion of the image as the spider walks, the motion in the lateral field of view being the most important. The preference of a lateral optic flow over the ventral flow can be explained by the difference in the resolution capacity of the posterior lateral eyes and the anterior lateral eyes.
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Homing in the wolf spider Lycosa tarantula (Araneae, Lycosidae): the role of active locomotion and visual landmarks
Naturwissenschaften, 2009Co-Authors: Carmen Reyes-alcubilla, M A Ruiz, J. Ortega-escobarAbstract:Previous studies on the homing of the wolf spider Lycosa tarantula have shown that it is carried out by path integration. Animals using this mechanism must measure the distance walked and the angles turned. This study aims to understand if wolf spider L . tarantula is able to estimate the walked distance in an outward path. As this information is more likely obtained by proprioceptive mechanisms, active or passive displacements have been performed. An active locomotion was found essential to estimate distances. During passive locomotion, spiders searched for their burrows near the release point while when displaced actively the inbound journey was longer than the outbound one. The possible use of visual landmarks near the burrow was also tested as a cue to complete the inbound journey. Our results did not show that L . tarantula used these visual landmarks to find the burrow. L . tarantula seems to use only proprioceptive information obtained during the outbound path to estimate the distance traveled.
M A Ruiz - One of the best experts on this subject based on the ideXlab platform.
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Visual odometry in the wolf spider Lycosa tarantula (Araneae: Lycosidae)
Journal of Experimental Biology, 2014Co-Authors: J. Ortega-escobar, M A RuizAbstract:The wolf spider Lycosa tarantula homes using path integration. The angular component of the displacement is measured using a polarized-light compass associated with the functioning of the anterior median eyes. However, how L. tarantula estimates the linear component of the displacement was not known prior to this investigation. The ability of L. tarantula to gauge the distance walked after being displaced from its burrow was investigated using experimental channels placed in an indoor setup. Firstly, we manipulated the perception of visual stimuli by covering all the spider's eyes. Secondly, we changed the optic flow supplied by a black-and-white grating (λ=2 cm) perceived either in the lateral or in the ventral field of view. Finally, the period of the lateral or ventral grating was changed from λ=2 cm to λ=1 cm. Our results indicate that visual information contributes to distance estimation because when the spider's eyes were covered, the spiders tended to search for the burrow at very variable distances. This visual information is created by the motion of the image as the spider walks, the motion in the lateral field of view being the most important. The preference of a lateral optic flow over the ventral flow can be explained by the difference in the resolution capacity of the posterior lateral eyes and the anterior lateral eyes.
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Homing in the wolf spider Lycosa tarantula (Araneae, Lycosidae): the role of active locomotion and visual landmarks
Naturwissenschaften, 2009Co-Authors: Carmen Reyes-alcubilla, M A Ruiz, J. Ortega-escobarAbstract:Previous studies on the homing of the wolf spider Lycosa tarantula have shown that it is carried out by path integration. Animals using this mechanism must measure the distance walked and the angles turned. This study aims to understand if wolf spider L . tarantula is able to estimate the walked distance in an outward path. As this information is more likely obtained by proprioceptive mechanisms, active or passive displacements have been performed. An active locomotion was found essential to estimate distances. During passive locomotion, spiders searched for their burrows near the release point while when displaced actively the inbound journey was longer than the outbound one. The possible use of visual landmarks near the burrow was also tested as a cue to complete the inbound journey. Our results did not show that L . tarantula used these visual landmarks to find the burrow. L . tarantula seems to use only proprioceptive information obtained during the outbound path to estimate the distance traveled.
Song-ping Liang - One of the best experts on this subject based on the ideXlab platform.
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a survey of the venom of the spider Lycosa vittata by biochemical pharmacological and transcriptomic analyses
Toxicon, 2015Co-Authors: Fan Zhang, Song-ping Liang, Changjun Liu, Huaxin Tan, Hengyun Wang, Yinjie Jiang, Fuping Zhang, Zhonghua LiuAbstract:Lycosa vittata, mainly distributed in the southwest of China, is a medium-sized and venomous spider, whose venom remains unexplored so far. This study aims to present an overview of the venom. It mainly consisted of diverse peptides and exhibited inhibitory effects on voltage-gated ion channels in rat dorsal root ganglia neurons, with a strongest inhibition on tetrodotoxin-sensitive and tetrodotoxin-resistant voltage-gated Na(+) channels. Interestingly, it exerted cytotoxicity to cancer cells, with approximately 10-fold selectivity on PC-3 over others, implying the existence of selective anti-PC-3 agents in the venom. Moreover, 51 toxin-like peptides were deduced from the venom gland transcriptome. Bioinformatic analyses suggested their structures might have some distinguished properties and their predicted functions were consistent with the venom activities. This study suggests that the venom is an attractive source of neurotoxins with therapeutic significance, and provides references for the structure and function investigation of specific toxins in the future.
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a novel spider peptide toxin suppresses tumor growth through dual signaling pathways
Current Molecular Medicine, 2012Co-Authors: Zhiqiang Liu, Mi Deng, J W Xiang, Y Zhao, Song-ping LiangAbstract:Spider venom is a large pharmacological repertoire containing many biologically active peptides, which may have a potent therapeutic implication. Here we investigated a peptide toxin, named lycosin-I, isolated from the venom of the spider Lycosa singoriensis. In contrast to most spider peptide toxins adopting inhibitor cystine knot (ICK) motif, lycosin-I shows a linear amphipathic alpha-helical conformation, common to α-helical host defense peptides. Lycosin-I displays strong ability to inhibit cancer cell growth in vitro and can effectively suppresses tumor growth in vivo. Mechanistically, it activates the mitochondrial death pathway to sensitize cancer cells for apoptosis, as well as up-regulates p27 to inhibit cell proliferation. Taken together, our results provide the first evidence that a spider toxin can effectively suppress tumorigenesis through activation of dual signaling pathways. In addition, lycosin-I may be a useful structural lead for the development of novel anticancer drugs.
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transcriptome analysis of the venom glands of the chinese wolf spider Lycosa singoriensis
Zoology, 2010Co-Authors: Yongqun Zhang, Zhonghua Liu, Jinjun Chen, Xing Tang, Fan Wang, Liping Jiang, Xia Xiong, Meichi Wang, Mingqiang Rong, Song-ping LiangAbstract:The wolf spider Lycosa singoriensis is a hunting spider with a widespread distribution in northwest China. The venom gland of spiders, which is a very specialized secretory tissue, can secrete abundant and complex toxin components. To extensively examine the transcripts expressed in the venom glands of L. singoriensis, we generated 833 expressed sequence tags (ESTs) from a directional cDNA library. Toxin-like sequences account for 69.1% of these ESTs, 17.3% are similar to cellular transcripts and 13.6% have no significant similarity to any known sequences. Here, we identified 223 novel toxin-like sequences, which can be classified into six different superfamilies; that means a novel potential source of ligands for varied ion channels was discovered. With the aid of Gene Ontology terms and homology to eukaryotic orthologous groups, the annotation of cellular transcripts revealed some cellular processes important for the toxin secretion of venom glands including protein synthesis, protein folding, tuned post-translational processing and trafficking, etc.
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biochemical and pharmacological study of venom of the wolf spider Lycosa singoriensis
Journal of Venomous Animals and Toxins Including Tropical Diseases, 2009Co-Authors: Zhen Liu, W Qian, Youyu Zhang, Song-ping LiangAbstract:The wolf spider Lycosa singoriensis is a large and venomous spider distributed throughout northwestern China. Like other spider venoms, the wolf spider venom is a chemical cocktail. Its protein content is 0.659 mg protein/mg crude venom as determined by the Lowry method. MALDI-TOF analysis revealed that the venom peptides are highly diverse and may be divided into three groups characterized by three independent molecular ranges: 2,000 to 2,500 Da, 4,800 to 5,500 Da and 7,000 to 8,000 Da, respectively. This molecular distribution differs substantially from those of most spider venoms studied so far. This wolf spider venom has low neurotoxic action on mice, but it can induce hemolysis of human erythrocytes. Furthermore, the venom shows antimicrobial activity against prokaryotic and eukaryotic cells.
Joaquin Ortegaescobar - One of the best experts on this subject based on the ideXlab platform.
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role of the anterior lateral eyes of the wolf spider Lycosa tarentula araneae lycosidae during path integration
Journal of Arachnology, 2006Co-Authors: Joaquin OrtegaescobarAbstract:Abstract Spiders of the species Lycosa tarentula (Linnaeus 1758) (Araneae, Lycosidae) use a vector navigation system while homing under natural conditions. Under laboratory conditions, in the absence of information relative to the sun's position or any pattern of polarized light, L. tarentula uses a path integration system which consists of turning at a fixed angle similar to one that could carry it to its burrow. In the absence of light, the angle is random. In this study we ask whether the spiders acquire the information about the angle turned during the outward journey through the anterior lateral eyes (ALEs), whose visual fields are directed towards the ground. To answer this question, two groups of animals were studied: one group with only the ALEs covered and another group with all eyes except ALEs covered. Our results show that ALE information alone is adequate to obtain the angle at which the animal should turn when homing.
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the visual system of Lycosa tarentula araneae lycosidae microscopic anatomy of the protocerebral optic centres
Italian Journal of Zoology, 2005Co-Authors: Jacqueline Kovoor, Arturo Munozcuevas, Joaquin OrtegaescobarAbstract:Abstract A new revised histological description of the protocerebral visual pathways of Lycosa tarentula (Araneae) is presented. Anatomical links are observed between the posterior and median retinae in the first optic neuropils, and between the anterior lateral and posterior lateral in the second optic neuropils. Long and wide in‐temeurons join all three indirect retinal laminae; their large somata are located among the third order globuli and their afferent fibres enter the “mushroom bodies”;, which are the third optic neuropils for the indirect retinae. Two of the optic neuropils for the anterior median retinae are completely isolated from those of the indirect retinae. A great number of the third order globuli for the anterior median retinae reach the voluminous and complex arcuate body, while a smaller number is oriented towards the “mushroom bodies”;. The visual pathways described are tentatively related to the behaviour of L. tarentula.
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circadian rhythms of locomotor activity in Lycosa tarentula araneae lycosidae and the pathways of ocular entrainment
Biological Rhythm Research, 2002Co-Authors: Joaquin OrtegaescobarAbstract:Lycosa tarentula is a ground-living spider that inhabits a burrow where it awaits the appearance of prey or conspecifics. In this study, circadian rhythms of locomotor activity were examined as well as the ocular pathway of entrainment. Thirty-three adult virgin females were examined under constant darkness (DD); all of them exhibited robust circadian rhythms of locomotor activity with period averaging 24.1 h. Fourteen of these spiders were studied afterwards under an LD 12:12 cycle; they usually entrained to in the first or second days, even when light intensity was as low as 1 lx. During the LD cycle, locomotor activity was generally restrained to the darkness phase although several animals showed a small amount of diurnal activity. Ten males were also examined under LD; they also were nocturnal but were much more active than the females. Seven females were examined under constant light (LL); under this they became arrhythmic. Except for the anterior median eyes (AMEs), all the eyes were capable of entraining the locomotor activity to an LD cycle. These results demonstrate that under laboratory conditions and low light intensities loco motor activity of Lycosa tarentula is circadian and in accordance with Aschoff’s ‘rule’. Only AMEs are unable to entrain the rhythm; the possible localization of circadian clock is therefore discussed.
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evidence that the wolf spider Lycosa tarentula araneae lycosidae needs visual input for path integration
Journal of Arachnology, 2002Co-Authors: Joaquin OrtegaescobarAbstract:Abstract The homing behavior of Lycosa tarentula (Linnaeus 1758) (Araneae, Lycosidae) adult females was studied. They were tested under two conditions, diffused light (200 lux) and darkness, after having been placed in an open field. In both conditions the spiders did not orient towards the burrow position; instead, under diffused light, each spider turned at a constant angle with a value close to135°; this is the turn that the spider should have made in its terrarium to return to the burrow. In darkness, most of the spiders (71.4%) turned at random. In both conditions, the trajectory was roughly straight, finishing with a sudden directional change. The speed was higher under diffused light than under darkness. These results support the hypothesis that L. tarentula uses path integration in laboratory conditions and that it needs visual input to obtain a direction estimation in homing.
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circadian structural changes in the retina of Lycosa tarentula araneae lycosidae
Biological Rhythm Research, 1999Co-Authors: Jacqueline Kovoor, Joaquin Ortegaescobar, Arturo MunozcuevasAbstract:Daily structural changes of the rhabdoms are described in the four eye types of a lycosid spider submitted to laboratory conditions: LD 12:12 (light on at 08.00, 100 lux). From a study of animals submitted to constant darkness during fourteen days, rhabdom turnover was shown to be circadian. Each type of retina exhibits its own rhythmic turnover of rhabdoms. Anterior-lateral, posterior-median and lateral eyes are mostly diurnal; anterior-median retinae comprise 300 receptors with mainly nocturnal functioning and 150 receptors with mainly diurnal functioning. A correlation was found between rhythms of locomotor activity, other activity, and rhabdom turnover in L. tarentula suggesting that the same pacemaker controls these different rhythms.
Carmen Fernandezmontraveta - One of the best experts on this subject based on the ideXlab platform.
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molecular systematics of the wolf spider genus Lycosa araneae lycosidae in the western mediterranean basin
Molecular Phylogenetics and Evolution, 2013Co-Authors: Enric Planas, Carmen Fernandezmontraveta, Carles RiberaAbstract:In this study, we present the first molecular phylogeny of the wolf spider genus Lycosa Latreille, 1804 in the Western Mediterranean Basin. With a wide geographic sampling comprising 90 localities and including more than 180 individuals, we conducted species delimitation analyses with a Maximum Likelihood approach that uses a mixed Yule-coalescent model to detect species boundaries. We estimated molecular phylogenetic relationships employing Maximum Likelihood and Bayesian Inference methods using mitochondrial and nuclear sequences. We conducted divergence time analyses using a relaxed clock model implemented in BEAST. Our results recovered 12 species that form four groups: Lycosa tarantula group comprising L. tarantula the type species of the genus, L. hispanica and L. bedeli; Lycosa oculata group composed of L. oculata, L. suboculata and three putative new species; Lycosa baulnyi group formed by the maghrebian L. baulnyi and L. vachoni and Lycosa fasciiventris group that includes two widespread species, L. fasciiventris and L. munieri. We found that each group of species shows a characteristic burrowing behavior and molecular and morphological diagnostic characters. Molecular clock analyses support the hypothesis of a relatively recent evolutionary origin of diversification of the group (4.96 Mya (3.53–6.45 Mya)). The establishment of the Mediterranean-like climate and the Pleistocenic glacial cycles seem to have been the main factors that promoted the diversification within the group. Finally, the results obtained in this study together with the revision of museum specimens, descriptions, redescriptions and illustrations, lead us to propose 18 nomenclatural changes (synonymies, generic transfers and nomina dubia) concerning the genera Lycosa, Allocosa and Hogna in the Western Mediterranean.
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substrate borne vibrations produced by male Lycosa tarentula fasciiventris araneae lycosidae during courtship and agonistic interactions
Ethology, 2010Co-Authors: Carmen Fernandezmontraveta, Alain SchmittAbstract:Substrate-borne vibrations produced by males of the Wolf Spider Lycosa tarentula fasciiventris during courtship and agonistic interactions under laboratory conditions are described (frequency and time domain). Vibrations were recorded on the substrate using an accelerometer placed 6 cm away from the female burrow entrance. Males produce different vibratory displays during courtship and agonistic interactions. Courtship displays involve anterior-posterior oscillations of the pedipalps which usually scratch the substrate, as well as occasional oscillations of the opisthosoma from top to bottom. They give rise to vibrations consisting of scries of syllables (duration of the series 4.5 ± 2.5 s) separated by silent periods of 7.2 ± 2 s. Series and silent periods arc produced consecutively for up to 20 min
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timing and patterns of mating in a free ranging population of Lycosa tarantula araneae lycosidae from central spain
Canadian Journal of Zoology, 2003Co-Authors: Carmen Fernandezmontraveta, Mariano CuadradoAbstract:We analysed the timing and patterns of mating in a free-ranging population of the wolf spider Lycosa tarantula (Araneae, Lycosidae) in central Spain monitored during a whole reproductive period. Th...
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spatial distribution of Lycosa tarentula fasciiventris araneae lycosidae in a population from central spain
Journal of Arachnology, 1991Co-Authors: Carmen Fernandezmontraveta, Rafael Lahozbeltra, Joaquin OrtegaAbstract:The burrow spatial distribution pattern in a population of Lycosa tarentula fasciiventris from central Spain was studied . The developmental stage of the individua l occupying the burrow, as well as the burrow spatial coordinates were measured during th e spring and summer. A three-dimensional distribution pattern was obtained and Morisita , mean-crowding and variance-mean coefficient indices of burrow density were calculated. The burrow distribution pattern changed throughout the study period . Subadult burro w location shows a tendency toward instability whereas location stability of adult individual s is greater. In both cases there is a tendency towards clumping, which is lesser in the case o f adult animals: if mean distances among burrows are compared between clumps, a tendenc y towards regularity results in the latter case. The observed distribution pattern might be a result of interspecific competition leading to a territorial system, with adult females con - stituting the structural support of the population . Resumen . Hemos estudiado el patron de distribucion espacial de una poblacion d e Lycosa tarentula fasciiventrisdel centro de Espana . Durante la primavera y el verano, s e midieron las coordenadas espaciales de los nidos, asi como la fase de desarrollo del individu o que lo ocupaba . A partir de los datos, se ha reconstruido el patron tridimensional d e distribucion, y se han calculado los indices de Morisita y mean-crowding, asi como el cocient e varianza-media de la densidad de losnidos. A lo largo del periodo de estudio se observa una modificacion en el patron de distribucion de los nidos . Los nidos de los individuo s subadultos muestran una tendencia a la inestabilidad, mientras que los ocupados por in- dividuos adultos tienen una localizacion mas estable . En ambos casos, se observa un a tendencia a la agregacion, que es menos marcada para los individuos adultos : si se compara n las distancias medias entre los nidos dentro de cada agregado, aparece una tendencia a l a regularidad en el ultimo caso. El patron de distribucion espacial podria ser el resultado de la competition intraespecifica, que determinaria un sistema de tipo territorial, siendo la s hembras adultas el soporte estructural de la poblacion.
