Genetic-morphometric variation in Culex quinquefasciatus from Brazil and La Plata, Argentina

Variation among natural populations of Culex (Culex) quinquefasciatus Say is associated with different vectorial capacities. The species Cx. quinquefasciatus is present in the equatorial, tropical and subtropical zones in the Brazilian territory, with intermediate forms between Cx. quinquefasciatus and Culex pipiens occurring in regions of latitudes around 33°-35°S. Herein, we studied geographically distinct populations of Cx. quinquefasciatus by genetic characterization and analysis of intra-specific wing morphometrics. After morphological analysis, molecular characterization of Cx. quinquefasciatus and intermediate forms was performed by polymerase chain reaction of the polymorphic nuclear region of the second intron of the acetylcholinesterase locus. Additionally, the morphology of adult female wings collected from six locations was analyzed. Wing centroid sizes were significantly different between some geographical pairs. Mean values of R2/R2+3 differed significantly after pairwise comparisons. The overall wing shape represented by morphometric characters could be divided into two main groupings. Our data suggest that Brazilian samples are morphologically and genetically distinct from the Argentinean samples and also indicated a morphological distinction between northern and southern populations of Brazilian Cx. quinquefasciatus. We suggest that wing morphology may be used for preliminary assessment of population structure of Cx. quinquefasciatusin Brazil

Natural and human forcing in recent geomorphic change; case studies in the Rio de la Plata basin

An analysis of geomorphic system`s response to change in human and natural drivers in some areas within the Rio de la Plata basin is presented The aim is to determine whether an acceleration of geomorphic processes has taken place in recent years and, if so, to what extent it is due to natural (climate) or human (land-use) drivers Study areas of different size, socio-economic and geomorphic conditions have been selected: the Rio de la Plata estuary and three sub-basins within its watershed Sediment cores were extracted and dated ((210)Pb) to determine sedimentation rates since the end of the 19th century. Rates were compared with time series on rainfall as well as human drivers such as population, GDP, livestock load, crop area, energy consumption or cement consumption, all of them related to human capacity to disturb land surface Data on river discharge were also gathered Results obtained indicate that sedimentation rates during the last century have remained essentially constant in a remote Andean basin, whereas they show important increases in the other two, particularly one located by the Sao Paulo metropolitan area Rates in the estuary are somewhere in between It appears that there is an intensification of denudation/sedimentation processes within the basin. Rainfall remained stable or varied very slightly during the period analysed and does not seem to explain increases of sedimentation rates observed. Human drivers, particularly those more directly related to capacity to disturb land surface (GDP, energy or cement consumption) show variations that suggest human forcing is a more likely explanation for the observed change in geomorphic processes It appears that a marked increase in denudation, of a ""technological"" nature, is taking place in this basin and leading to an acceleration of sediment supply This is coherent with similar increases observed in other regions (C) 2010 Elsevier B V All rights reserved

Helmet use among motorcyclists: observational study in the city of Mar del Plata, Argentina

The objective of the study was to assess the use of helmets in a community where helmet use is mandatory but low as there is no police enforcement. A sample comprising 451 motorcyclists in the city of Mar del Plata, Argentina, was studied in 2006. The following variables were studied: gender, type of motorcycle, weather conditions, time of the day, city area and type of road where motorcyclists traveled. Data were analyzed through a multiple logistic regression model. An overall 40% prevalence (95% CI: 35.5;44.5) of helmet use was found. Higher rates of helmet use were seen among women, and under unfavorable weather conditions, lower rates were found in the city outskirts, and variable use was seen according to the type of motorcycle. There is a need to improve law enforcement and to promote education of motorcyclists.

Hydatidosis cases in one of Mar del Plata City hospitals, Buenos Aires, Argentina

Hydatidosis is a zoonosis of worldwide distribution produced mainly by the metacestode Echinococcus granulosus. In Argentina, its distribution reaches endemic levels. The aims of this investigation were to contribute to the knowledge of hydatidosis in the southeast of Buenos Aires province, study its evolution at the Interzonal General Hospital for Acute Diseases between 1992 and 2002 and discuss its importance. Clinical records of operated and/or diagnosed patients were reviewed with regard to this disease. One hundred and twenty cases were analyzed. Among the patients, 56.7% were women. The average age was 42.2+16.8 years. 68.3% lived in urban areas. In 75% of the cases, ultrasonography was used. Hepatic location was most frequently seen. 89.2% received surgical treatment. Albendazole was used for 19 patients. The mean length of hospital stay was 16 days. We conclude that this zoonosis is a disease that generates high costs in medical care and for this reason more epidemiological studies should be carried out and public health authorities should implement control and prevention strategies in the region.

Sewage impact on the composition and distribution of Polychaeta associated to intertidal mussel beds of the Mar del Plata rocky shore, Argentina

The polychaete composition and distribution within mussel beds were studied in order to assess organic pollution due to domestic sewage in a rocky shore of Mar del Plata (Argentina) during 1997. Four stations and a control site were randomly sampled around the local effluent. Quantitative data on polychaetes, as well as sediment accumulated among mussels and its organic carbon content were measured. Polychaete distribution patterns are related to the organic matter gradient, being Capitella cf. capitata, Neanthes succinea (Frey & Leuckart, 1847) and Boccardia polybranchia (Haswell, 1885) the dominant indicator species close to the effluent. At medial distances, the cirratulids Caulleriella alata (Southern, 1914) and Cirratulus cirratus (Müller, 1776) are very important in abundance. The syllids Syllis prolixa Ehlers, 1901 and S. gracilis Grube, 1840 are distributed along the study area, but dominate at the medial stations and at the control site. The orbiniid Protoariciella uncinata Hartmann-Schröder, 1962 is subdominant at the control station.

Morphological and functional study of the marginal sphincter of the sea anemones Phymactis clematis and Aulactinia marplatensis from intertidal of Mar del Plata, Argentina

It was made the characterization of marginal sphincter to the species Phymactis clematis (Drayton in Dana, 1849) and Aulactinia marplatensis (Zamponi, 1977), from intertidal ecosystem through their morphogical and functional study. The species P. clematis has a circumscript sphincter of palmate type. This muscle is constituted by a mesogloeal axis and several mesogloeal subaxes. Axis as well as subaxes give a support to the endoderm which border is smooth. Aulactinia marplatensis has a circunscript sphincter pinnate type. The axis has a truncated cone shape while in P. clematis the shape is cylindrical on its origin and it is bifurcated at the end. Both species experiments were carried out using the isolated muscles. They were stimulated at increasing KCl concentrations ranging from 20 to 200 mM. The results were analysed in the form of dose-response curves expressed in tension in grams force vs concentration. Contractil force increases in a sigmoid form to increasing KCl concentrations. The correlation between morphology and function and the differences shown in both species would be related to their intertidal distribution.

"Pro crosis argenti". La plata al comtat de les Muntanyes de Prades: explotació, gestió i rendiment de les mines de Falset durant la baixa edat mitjana

L’objectiu de la recerca que s’ha dut a terme durant el període 2004-2007 ha estat analitzar les característiques territorials, senyorials i jurisdiccionals del domini format pel comtat de les Muntanyes de Prades i la baronia d’Entença i, a partir d’aquí, aprofundir en un aspecte concret d’aquesta senyoria: l’explotació minera de l’argent durant els segles XIV i XV. En aquest sentit, la recerca s’ha fonamentat en l’estudi de la documentació relacionada amb aquesta qüestió que hi ha dipositada a l’Arxiu Ducal de Medinaceli; la qual, però, s’ha pogut buidar i analitzar a través de la consulta de les còpies microfilmades que se’n conserven al Monestir de Poblet. Com a resultats principals s’ha aconseguit delimitar territorialment el comtat de les Muntanyes de Prades i baronia d’Entença i determinar-ne la titularitat jurisdiccional a mitjan segle XIV. A més, s’han establert els paràmetres que marquen i expliquen l’evolució de la normativa que regulava l’explotació minera de l’argent. I, finalment, s’ha pogut determinar que, segurament, la major part de l’argent produït a mitjan segle XIV es va obtenir a partir de minerals d’argent i argent natiu.

Avantpassats de plata

Treball de recerca realitzat per una alumna d'ensenyament secundari i guardonat amb un Premi CIRIT per fomentar l'esperit científic del Jovent l'any 2009. El treball es centra en conèixer la complexitat d’un estudi fotogràfic del s. XIX: l’estudi Napoleón. Per entendre tots els aspectes que implicava fer una fotografia en aquest estudi comença explicant com es van desenvolupar i descobrir les diferents tècniques fotogràfiques, després presenta l’estat de la fotografia a la Catalunya del s. XIX. El nucli del treball té diferents aspectes: per una banda s’investiga la història dels fundadors d’un dels estudis més importants a la Barcelona del s. XIX, per l’altra presenta com eren les sales, els decorats, els clients, la tipografia, les càmeres .... i per últim, porta a la pràctica tot allò necessari per a transformar un paper blanc en una fotografia fent servir els mètodes de l’època. Podríem dir que el treball es desenvolupa en tres àmbits: el primer sobre els fonaments tècnics i històrics de la fotografia, les fonts utilitzades per realitzar aquest apartat han estat fonamentalment bibliogràfiques; el segon fa referència a l’estudi fotogràfic dels Napoleón, en aquest cas, a part de les fonts bibliogràfiques, també ha estat de vital importància la informació aportada per un descendent de la família i finalment s’explica els procediments que es van fer servir per obtenir imatges durant el segle s.XIX i les reaccions químiques en les quals es fonamenten. Aporta també una part experimental que dóna un caire artístic i novedós al treball.

Human toxocarosis. Its seroprevalence in the City of La Plata

Toxocara canis is very common in dogs throughout the world. It is the primary cause of visceral larva migrans (VLM) in humans. Soil contaminated with T. canis embryonated eggs is the main source of infection of man. Our objective was to describe Toxocara seroprevalence in humans in the city of La Plata associated with some determinants such asage, presence or absence of clinical manifestations and risk factors. Blood samples were collected at random from 156 patients of different sex and age, with and without clinical symptoms compatible with the disease. The diagnostic technique ELISA test was performed with the Bordier Affinity Products Commercial Kit, using excretory-secretory Toxocara antigen with a sensitivity higher than 90%. The values were positive in 39% of the studied population. In the analysis according to age, the younger group presented significant differences with respect to the older one (Chi-square p<0.05). Positive patients presented clinical symptoms compatible with the disease (84%), and 41% presented some risk factor. The level of positivity obtained indicates a certain risk of being infectes mainly in patients younger than 15 years old. The authors agree that an early identification and treatment of VLM may save a life.

Susceptibility and compatibility of Biomphalaria tenagophila from the Río de la Plata basin with Schistosoma mansoni from Brazil

Schistosomiasis has expanded to southern parts of Brazil. Between 2005-2007 the dispersion and the proliferation of Biomphalaria tenagophila was verified in the province of Corrientes near the Brazilian border. In order to study the possibility that schistosomiasis might spread into the basins of the Paraná and Uruguay Rivers, 440 B. tenagophila collected from 10 populations groups were experimentally exposed to infection with Schistosoma mansoni of the SJ2 strain. Snails from five localities were susceptible. Frandsen's index (TCP/100) shows that those snails from Mirungá (11%), Aguacerito (2%) and Curupicay (2%) were Class I and not very compatible. Meanwhile, snails from Copra (6%) and Pay-Ubre (22%), in the Paraná River basin, were Class II and poorly compatible.

Genetic-morphometric variation in Culex quinquefasciatus from Brazil and La Plata, Argentina

Variation among natural populations of Culex (Culex) quinquefasciatus Say is associated with different vectorial capacities. The species Cx. quinquefasciatus is present in the equatorial, tropical and subtropical zones in the Brazilian territory, with intermediate forms between Cx. quinquefasciatus and Culex pipiens occurring in regions of latitudes around 33°-35°S. Herein, we studied geographically distinct populations of Cx. quinquefasciatus by genetic characterization and analysis of intra-specific wing morphometrics. After morphological analysis, molecular characterization of Cx. quinquefasciatus and intermediate forms was performed by polymerase chain reaction of the polymorphic nuclear region of the second intron of the acetylcholinesterase locus. Additionally, the morphology of adult female wings collected from six locations was analyzed. Wing centroid sizes were significantly different between some geographical pairs. Mean values of R2/R2+3 differed significantly after pairwise comparisons. The overall wing shape represented by morphometric characters could be divided into two main groupings. Our data suggest that Brazilian samples are morphologically and genetically distinct from the Argentinean samples and also indicated a morphological distinction between northern and southern populations of Brazilian Cx. quinquefasciatus. We suggest that wing morphology may be used for preliminary assessment of population structure of Cx. quinquefasciatusin Brazil.

Precipitacion de plata en efluentes electroliticos

La recuperación de plata contenida en efluentes electrolíticos es atractiva por su alto valor económico. Estos efluentes son catalogados como residuos tóxicos y no pueden ser evacuados a cauces públicos sin un tratamiento previo de detoxificación. Una de las vías propuestas para recuperar plata de este tipo de efluentes es la precipitación química utilizando ditionito de sodio, borohidruro de sodio o monohidrato de hidracina. En este trabajo, se discuten los aspectos más signifícativos de la utilización de estos reactivos para el citado objetivo. Se presentan resultados de la precipitación de plata con ditionito de sodio en efluentes base tiosulfato, sin eliminación de otras especies presentes. Se pone de maniflesto la capacidad de este reactivo de cumplir los objetivos de alcanzar una precipitación, prácticamente total, de la plata, dejando el metal en el efluente a niveles de menos de 1 ppm, sin introducir substancias extrañas al sistema.

Sexual foraging segregation in South American sea lions increases during the pre-breeding period in the La Plata River plume

Stable carbon and nitrogen isotopes in skin and bone of South American sea lions from Brazil and Uruguay were analysed to test the hypothesis that trophic overlap between the sexes is lower during the pre-breeding season than throughout the rest of the year. The isotopic values of skin and bone were used to infer the trophic relationships between the sexes during the pre-breeding period and year round, respectively. Prey species were also analysed to establish a baseline necessary for interpreting the stable isotope ratios of skin and bone. Standard ellipse areas, estimated using Bayesian inference in the SIBER routine of the SIAR package in R, suggested that males and females used a wide diversity of foraging strategies throughout the year and that no differences existed between the sexes. However, the diversity of foraging strategies was largely reduced during the pre-breeding period, with all the individuals of each sex adopting similar strategies, but with the two sexes differing considerably in stable isotope values and the ellipse areas of males and females not overlapping at all. Nevertheless, the results revealed a general increase in the consumption of pelagic prey by both sexes during the pre-breeding period. The progressive crowding of individuals in the areas surrounding the breeding rookeries during the pre-breeding period could lead to an increase in the local population density, which could explain the above reported changes.