Identification of individual neurons reflecting short- and long-term visual memory in an arthropod

Ideally, learning-related changes should be investigated while they occur in vivo, but physical accessibility and stability limit intracellular studies. Experiments with insects and crabs demonstrate their remarkable capacity to learn and memorize visual features. However, the location and physiology of individual neurons underlying these processes is unknown. A recently developed crab preparation allows stable intracellular recordings from the optic ganglia to be performed in the intact animal during learning. In the crab Chasmagnathus, a visual danger stimulus (VDS) elicits animal escape, which declines after a few stimulus presentations. The long-lasting retention of this decrement is mediated by an association between contextual cues of the training site and the VDS, therefore, called context-signal memory (CSM). CSM is achieved only by spaced training. Massed training, on the contrary, produces a decline of the escape response that is short lasting and, because it is context independent, is called signal memory (SM). Here, we show that movement detector neurons (MDNs) from the lobula (third optic ganglion) of the crab modify their response to the VDS during visual learning. These modifications strikingly correlate with the rate of acquisition and with the duration of retention of both CSM and SM. Long-term CSM is detectable from the response of the neuron 1 d after training. In contrast to MDNs, identified neurons from the medulla (second optic ganglion) show no changes. Our results indicate that visual memory in the crab, and possibly other arthropods, including insects, is accounted for by functional changes occurring in neurons originating in the optic lobes.Fil:Tomsic, D. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Berón de Astrada, M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Sztarker, J. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Geographical limits of the Southeastern distribution of <i>Aedes aegypti</i> (Diptera, Culicidae) in Argentina

Aedes aegypti (Linnaeus) is a human-biting mosquito and the primary vector of human dengue and yellow fever viruses; it is also considered the principal vector of Chikungunya virus in Asia. In particular, dengue and dengue hemorrhagic fever constitute an important burden to humankind in terms of morbidity and mortality. About 3.6 billion people in the tropics, mainly in Asia, the Western Pacific region, the Caribbean, and Central and South America, live under risk of infection with one or more of the four dengue virus serotypes (DEN-1 to DEN-4), and recent reports estimate over 230 million infections, over 2 million cases of the severe form of the disease, and 21,000 deaths. (Párrafo extraído del texto a modo de resumen)Facultad de Ciencias Naturales y Muse

Geographical limits of the Southeastern distribution of <i>Aedes aegypti</i> (Diptera, Culicidae) in Argentina

Aedes aegypti (Linnaeus) is a human-biting mosquito and the primary vector of human dengue and yellow fever viruses; it is also considered the principal vector of Chikungunya virus in Asia. In particular, dengue and dengue hemorrhagic fever constitute an important burden to humankind in terms of morbidity and mortality. About 3.6 billion people in the tropics, mainly in Asia, the Western Pacific region, the Caribbean, and Central and South America, live under risk of infection with one or more of the four dengue virus serotypes (DEN-1 to DEN-4), and recent reports estimate over 230 million infections, over 2 million cases of the severe form of the disease, and 21,000 deaths.\n(Párrafo extraído del texto a modo de resumen)</i

Geographical limits of the Southeastern distribution of <i>Aedes aegypti</i> (Diptera, Culicidae) in Argentina

Aedes aegypti (Linnaeus) is a human-biting mosquito and the primary vector of human dengue and yellow fever viruses; it is also considered the principal vector of Chikungunya virus in Asia. In particular, dengue and dengue hemorrhagic fever constitute an important burden to humankind in terms of morbidity and mortality. About 3.6 billion people in the tropics, mainly in Asia, the Western Pacific region, the Caribbean, and Central and South America, live under risk of infection with one or more of the four dengue virus serotypes (DEN-1 to DEN-4), and recent reports estimate over 230 million infections, over 2 million cases of the severe form of the disease, and 21,000 deaths. (Párrafo extraído del texto a modo de resumen)Facultad de Ciencias Naturales y Muse

Investigaciones sobre mosquitos de Argentina

Este libro se compone de seis secciones: 1. Taxonomía, 2. Distribución, 3. Ecología, 4. Eco-epidemiología de enfermedades transmitidas por mosquitos, 5. Control de poblaciones de mosquitos y 6. Aspectos culturales prevención y acción comunitaria. Cada sección fue coordinada por especialistas de cada temática. Los 28 capítulos que conforman el libro fueron escritos por investigadores provenientes de todas las regiones del país, quienes exponen los avances más recientes de cada área, y destacan y comentan los estudios realizados en Argentina. De este modo, cada capítulo ofrece al lector una visión realista de los avances que se han realizado en Argentina en torno a los mosquitos, su implicancia en la salud humana, y su control, tanto de las especies nativas como de las invasoras. En las primeras tres secciones se abordaron aspectos puramente biológicos, en la cuarta sección se integran los aspectos ecológicos con los epidemiológicos, en la quinta sección se aborda el control de los mosquitos vectores desde las técnicas químicas y biológicas. Debido a que la problemática del control de mosquitos no solo tiene una componente biológica sino también social, se incluyó la sexta sección, que trata sobre los aspectos culturales y las acciones a desarrollar por la comunidad. Esta sección invita a incursionar desde un enfoque diferente y necesario, a la concientización de la ciudadanía en el control de los mosquitos vectores. Como cierre, se presentan a modo de epílogo, las proyecciones de las investigaciones realizadas hasta el presente, y las necesidades a futuro, invitando a reflexionar y a debatir los caminos a tomar de aquí en más, además de incentivar a las nuevas generaciones de investigadores a continuar con las investigaciones e incursionar en nuevos enfoques de un mismo problema.Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET

Genetic Evidence of Expansion by Passive Transport of Aedes (Stegomyia) aegypti in Eastern Argentina

Aedes (Stegomyia) aegypti (Linnaeus) (Diptera: Culicidae) is the principal vector of the yellow fever virus, the five dengue virus serotypes (DENV-1 to DENV-5), chikungunya virus, Zika virus, and several types of encephalitis [1–3]. The behavior of this species is synanthropic and anthropophilic, being the culicid most closely associated with human populations [4]. The incidence of dengue has increased 30-fold over the last 50 years; according to the World Health Organization, up to 50–100 million infections occur each year in over 100 endemic countries, and at least one half of the world’s population has risk of being infected with dengue virus [5]. Chikungunya virus has been responsible for over 2 million human infections during the past decade and is currently moving to subtropical latitudes as well as to the western hemisphere. Up until April 2015, there have been 1,379,788 suspected cases of this disease in the Caribbean islands, Latin America, and the United States. This expansion into novel habitats brings unique risks associated with further spread of the virus and the disease it causes [6]. On the other hand, there are about 200,000 cases of yellow fever each year worldwide responsible for about 30,000 deaths, most of them from Africa. Zika virus is an emerging mosquito-borne virus, with outbreaks in Africa, Asia, and the Pacific between 2007 and 2014. Since 2015, there has been an increase in reports of ZIKV infection in the Americas, with Brazil being the most affected country, with 534 confirmed cases and 72,062 suspected cases between 2015 and 2016 [7]. All these viruses and the mosquito vector A. aegypti present in the Americas represent a serious risk. So far, in 2016, 39,926 dengue cases produced by DENV-1 and DENV-4 serotypes and 319 autochthonous cases of chikungunya fever have been reported in Argentina. According to the last census, Argentina has approximately 40 million people (National Institute of Statistics and Censuses of Argentina [INDEC], Census 2010), and over 38 million live in areas suitable for the transmission of dengue and chikungunya viruses [8]. Moreover, although there were 22 imported cases of Zika and 24 autochthonous cases confirmed in Argentina, there is a high incidence of cases in Brazil, and besides that, there is an internal circulation of the virus in the neighboring countries Brazil, Paraguay, and Bolivia [7,8], in addition to the constant expansion of the mosquito vector.Facultad de Ciencias Naturales y Muse

Cortactin Is Involved in the Entry of Coxiella burnetii into Non-Phagocytic Cells

BACKGROUND: Cortactin is a key regulator of the actin cytoskeleton and is involved in pathogen-host cell interactions. Numerous pathogens exploit the phagocytic process and actin cytoskeleton to infect host cells. Coxiella burnetii, the etiologic agent of Q fever, is internalized by host cells through a molecular mechanism that is poorly understood. METHODOLOGY/PRINCIPAL FINDING: Here we analyzed the role of different cortactin motifs in the internalization of C. burnetii by non-phagocytic cells. C. burnetii internalization into HeLa cells was significantly reduced when the cells expressed GFP-cortactin W525K, which carries a mutation in the SH3 domain that renders the protein unable to bind targets such as N-WASP. However, internalization was unaffected when the cells expressed the W22A mutant, which has a mutation in the N-terminal acidic region that destroys the protein's ability to bind and activate Arp2/3. We also determined whether the phosphorylation status of cortactin is important for internalization. Expression of GFP-cortactin 3F, which lacks phosphorylatable tyrosines, significantly increased internalization of C. burnetii, while expression of GFP-cortactin 3D, a phosphotyrosine mimic, did not affect it. In contrast, expression of GFP-cortactin 2A, which lacks phosphorylatable serines, inhibited C. burnetii internalization, while expression of GFP-cortactin SD, a phosphoserine mimic, did not affect it. Interestingly, inhibitors of Src kinase and the MEK-ERK kinase pathway blocked internalization. In fact, both kinases reached maximal activity at 15 min of C. burnetii infection, after which activity decreased to basal levels. Despite the decrease in kinase activity, cortactin phosphorylation at Tyr421 reached a peak at 1 h of infection. CONCLUSIONS/SIGNIFICANCE: Our results suggest that the SH3 domain of cortactin is implicated in C. burnetii entry into HeLa cells. Furthermore, cortactin phosphorylation at serine and dephosphorylation at tyrosine favor C. burnetii internalization. We present evidence that ERK and Src kinases play a role early in infection by this pathogen

Médano La Enriqueta: un lugar de entierro de cazadores tardíos sobre el río Colorado (dpto. Caleu Caleu, provincia de La Pampa)

En este trabajo se presentan los primeros resultados obtenidos sobre las evidencias bioarqueológicas y culturales recuperadas en el sitio Médano La Enriqueta I (MLE-I). Este sitio constituye una manifestación de asentamiento prehispánico del sector sur del departamento Caleu-Caleu. MLE-I se localiza sobre un médano activo, en el cual se identificaron tres hoyadas que se corresponden con sectores de uso diferencial del espacio por parte de las poblaciones prehispánicas. En una de ellas se detectaron inhumaciones de restos humanos, mientras que en otra el registro recuperado sugiere actividades diversas. A partir del análisis del conjunto esqueletal, fue posible identificar un NMI de 9. Se destacan dos cráneos con deformación intencional de tipo tabular erecta, variante planolámbdica, cuya cronología radiocarbónica, asignada al Holoceno tardío final (1005±25 años ap), concuerda con otros casos identificados. Se recuperó también una destacada variabilidad de restos culturales principalmente representados por artefactos líticos, fragmentos cerámicos y restos malacológicos. Los datos obtenidos a partir de la implementación de diferentes líneas de análisis son discutidos e integrados con los antecedentes del norte de Patagonia y sur de la provincia de La Pampa.This paper presents the first results obtained on bioarchaeological and cultural evidence recovered at Médano La Enriqueta I site (MLE-I). This site is a case of human prehispanic settlement in the southern area of Caleu-Caleu Department. MLE-I is located on an active dune, in which three hollows, were found, probably related with the differential use of space by prehispanic hunter-gatherers societies, were found. human remains were recovered from one of these hollows, while in another the cultural record is a consequence of other human activities. From the archaeological analysis it was possible to estimate a MNI of nine. Two skulls with intentional deformation (tabular erect type, planolambdic variant) were recovered, whose radiocarbon chronology, assigned to the final late holocene (1005±25 years bp), agrees with other cases known in the area. Finally, a remarkable variability of cultural remains, mainly represented by lithic artifacts, pottery fragments and malacological beads (chaquiras), were recovered. The data obtained by applying different lines of analysis are discussed and integrated with previous research developed in northern Patagonia and southern La Pampa Province.Facultad de Ciencias Naturales y Muse

Médano La Enriqueta: un lugar de entierro de cazadores tardíos sobre el río Colorado (dpto. Caleu Caleu, provincia de La Pampa)

En este trabajo se presentan los primeros resultados obtenidos sobre las evidencias bioarqueológicas y culturales recuperadas en el sitio Médano La Enriqueta I (MLE-I). Este sitio constituye una manifestación de asentamiento prehispánico del sector sur del departamento Caleu-Caleu. MLE-I se localiza sobre un médano activo, en el cual se identificaron tres hoyadas que se corresponden con sectores de uso diferencial del espacio por parte de las poblaciones prehispánicas. En una de ellas se detectaron inhumaciones de restos humanos, mientras que en otra el registro recuperado sugiere actividades diversas. A partir del análisis del conjunto esqueletal, fue posible identificar un NMI de 9. Se destacan dos cráneos con deformación intencional de tipo tabular erecta, variante planolámbdica, cuya cronología radiocarbónica, asignada al Holoceno tardío final (1005±25 años ap), concuerda con otros casos identificados. Se recuperó también una destacada variabilidad de restos culturales principalmente representados por artefactos líticos, fragmentos cerámicos y restos malacológicos. Los datos obtenidos a partir de la implementación de diferentes líneas de análisis son discutidos e integrados con los antecedentes del norte de Patagonia y sur de la provincia de La Pampa.This paper presents the first results obtained on bioarchaeological and cultural evidence recovered at Médano La Enriqueta I site (MLE-I). This site is a case of human prehispanic settlement in the southern area of Caleu-Caleu Department. MLE-I is located on an active dune, in which three hollows, were found, probably related with the differential use of space by prehispanic hunter-gatherers societies, were found. human remains were recovered from one of these hollows, while in another the cultural record is a consequence of other human activities. From the archaeological analysis it was possible to estimate a MNI of nine. Two skulls with intentional deformation (tabular erect type, planolambdic variant) were recovered, whose radiocarbon chronology, assigned to the final late holocene (1005±25 years bp), agrees with other cases known in the area. Finally, a remarkable variability of cultural remains, mainly represented by lithic artifacts, pottery fragments and malacological beads (chaquiras), were recovered. The data obtained by applying different lines of analysis are discussed and integrated with previous research developed in northern Patagonia and southern La Pampa Province.Facultad de Ciencias Naturales y Muse

Taxonomía molecular de mosquitos

La correcta identificación de las especies es fundamental en los estudios de biología y otras ciencias relacionadas. En la actualidad, la taxonomía de culícidos basada en las características anatómicas y morfológicas externas, es la más aceptada y utilizada al momento de determinar la especie a la que pertenece un mosquito. Sin embargo, la identificación taxonómica sustentada en la observación de los caracteres morfológicos, suele ser dificultosa y limitada al bajo número de expertos que se dedican a esta área del conocimiento. Como alternativa y/o complemento a la identificación morfológica, desde hace algunos años se utilizan metodologías químicas y moleculares. Entre ellas, los sistemas de identificación basados en análisis de secuencias nucleotídicas del ácido desoxirribonucleico (DNA) son los más conocidos y extensamente aplicados. En particular, para especies de mosquitos fueron propuestos numerosos genes como unidad de análisis para la discriminación de entidades taxonómicas, y actualmente se está estudiando y discutiendo la utilidad de los mismos. A partir de estos genes se han generado numerosos cebadores capaces de amplificar, por medio de la reacción en cadena de la polimerasa, secuencias totales o parciales, que son posteriormente secuenciadas y analizadas. Entre ellos, se destacan cebadores capaces de amplificar fragmentos del gen de la subunidad ribosomal pequeña eucariota 18S, secuencias correspondientes a los espacios transcriptos internos, a la región 5´ del gen mitocondrial citocromo c oxidasa subunidad I y microsatélites. Hasta la fecha, los estudios de taxonomía molecular con especies de mosquitos de Argentina son muy escasos, solo algunos trabajos recientes analizan y discuten resultados obtenidos a partir de secuencias parciales de algunos de los genes anteriormente mencionados. En este capítulo se lleva a cabo una revisión de los diferentes genes que fueron utilizados para la identificación molecular de distintas especies de mosquitos y, en particular, de los que fueron utilizados para la identificación de especies presentes en Argentina. Finalmente, se discute la utilidad de estas técnicas y se describen las ventajas y desventajas de las mismas respecto de la taxonomía basada en caracteres morfológicos.Facultad de Ciencias Naturales y MuseoComisión de Investigaciones Científicas de la provincia de Buenos Aire