Central Region Of Argentina Research Articles

Food habits and impact of rooting behaviour of the invasive wild boar, Sus scrofa, in a protected area of the Monte Desert, Argentina

The wild boar, Sus scrofa, was introduced in the central region of Argentina in the early 20th century. A small feral population invaded the western area of the Man and Biosphere Reserve of Ñacuñán, Argentina in the early 1980’s. The purpose of our study was to provide information about the diet of wild boars in the semiarid region of Argentina and to assess their potential effect on vegetation through soil rooting. We analyzed 41 faecal samples and compared cover plant composition between rooted and non-rooted soil. Ninety-five percent of the wild boar diet consisted of different parts (leaves, stems, glumes, fruits, seeds, and bulbs) of 36 plant species, while arthropods and animal tissue represented only 5% of the diet. Two plant species ( Sphaeralcea miniata and Pitraea cuneato-ovata) composed the bulk of the diet, representing almost 50% of the total items found in the faeces. Plant cover was significantly different between rooted and non-rooted areas. Rooted areas were dominated by Pitraea cuneato-ovata, whereas the cover of Lycium sp was higher in non-rooted areas. This is the first study addressing the ecology of the wild boar in a protected area of the Monte Desert biome of Argentina.

Patterns in fish species composition and assemblage structure in the upper Salado River lakes, Pampa Plain, Argentina

The Pampa Plain, in the central region of Argentina, is mostly drained by the Salado River. The fish fauna of this river is mostly known from field collections in lower reach lakes. Consequently, we aimed to explore the composition and structure of the fish assemblages in the upper Salado River lakes. Patterns in dominance and persistence of species and assemblage level attributes were correlated with environmental and human activity-derived (NO3:NH4) variables. Overall, 19,913 individuals of 17 species included in 5 orders and 11 families were collected. Several species are first records for the upper Salado River lakes. There was a marked proliferation of species in the family Characidae. Conversely, the remainder 10 families were only represented by one or two species. The species composition along the study lakes changed slightly but their relative contribution to the total fish collected (dominance) varied greatly. Rather few species were present in all collections suggesting an important interannual variability in assemblage stability. The gradient in water conductivity was an important factor for the persistence of particular species in the lakes. The gradients in water conductivity and NO3:NH4 ratio were associated with particular fish communities dominated by different groups of species. These results suggest that even when broad management and conservation strategies should encompass the system as a whole, lake-specific approaches must also be addressed. Overall, our results highlight that human impacts on surface waters may interact with environmental factors to influence the dynamics of fish species and the structure of their communities.

Environmental determinants of the small mammal assemblage in an agroecosystem of central Argentina: The role of Calomys musculinus

Agricultural intensification in the central region of Argentina has been accompanied by rodent assemblage changes, involving an increase in Calomys species densities. In particular, Calomys musculinus, the main reservoir of Junín virus (etiological agent of the Argentine Haemorrhagic Fever, AHF) selects field borders over crop-fields. Borders represent relatively-stable habitats within agroecosystems, otherwise highly human modified landscapes. In this article, we assessed the effect of environmental variables on rodent species occurrence and assemblage in the field borders of a pampean agroecosystem. Small rodent occurrence was examined for variation according to vegetation species composition, structure and productivity, using canonical ordination techniques. In a total of 72 crop-field borders of Córdoba province, in spring, summer and autumn (2005-2006), we captured 1041 rodents of 8 different species. Akodon azarae, Calomys venustus and C. musculinus were the dominant species of the assemblage, with the first two associated one another, while C. musculinus tended to be related to different environmental variables. We showed that rodent species associations were mediated by resources that changed seasonally, such as vegetation cover. Also, the strength and “sign” of the association between species seemed to be a consequence of different habitat preferences and activity patterns. Finally, the intra-annual population cycle seemed to influence the relation between species and habitat structure and, possibly, inter-specific competition for resources. Therefore, we suggest that less generalist species of the rodent assemblage, well adapted to linear habitats, may limit C. musculinus occurrence throughout the agroecosystem by habitat and spatial competition. Any action aimed to control AHF, and therefore C. musculinus population density, should exclude negative effects on coexisting species.

Epidemiology of hip fracture in Tucuman, Argentina

The incidence of osteoporotic hip fracture was studied previously in a central area of Argentina. Studying Tucuman (north area) was very useful to compare results of the different areas and detect a similar incidence in women and a slightly higher incidence in men compared with previous data for the central region. Epidemiology of hip fracture was studied over a 1-year period in the city of San Miguel de Tucumán (SMT) and in the whole province of Tucumán, located in the northeast of Argentina (latitudes 26° and 28° south). The results were compared with previous studies performed in the central region of Argentina. Two hundred and eighty-three patients (208 women and 75 men) aged 50 years or over in SMT suffered a hip fracture. The incidence in females and males was 334.9 and 163.8 hip fractures per 100,000 inhabitants per year, respectively (female/male ratio 2.0). A total of 498 hip fractures were recorded in Tucuman province (367 in women and 131 in men). The results in females and males were 276.5 and 114.7 hip fractures per 100,000 inhabitants per year, respectively. Average age of the female and male population was 78±9 and 77±9 years, respectively. These results showed that the incidence of hip fracture in female and male populations in SMT was similar to previous studies performed in the central area of the country. Further studies on the south area of Argentina should be conducted to complete the information on a large country extending from latitudes 22° to 55°S.

Use of non-CODIS miniSTR markers: Creation of a database in Argentina

The use of miniSTR markers is a valuable tool in the forensic laboratory since it allows high-quality genetic profiles to be obtained on low copy number (LCN) or degraded DNA taken from different samples, such as cadaveric material, paraffin-embedded tissue, chewing gum, traces of saliva, pieces of cloth, cigarette butts, bone samples, etc. In addition, it is useful to have additional STR loci to solve paternity cases with one or more inconsistencies or to increase the amount of genetic information for incomplete family studies, where the genetic profile of the alleged father has to be reconstructed. Genetic frequencies and forensic parameters were calculated for 12 non-CODIS miniSTR loci (D20S480, D6S2439, D6S1056, D9S1118, D4S2639, D17S1290, D10S1248, D14S1434, D22S1045, D4S2364, D2S441 and D1S1677) from a total of 506 unrelated individuals from various provinces in the central region of Argentina (Cordoba, Buenos Aires, Salta, Entre Rios and Santa Fe). The application of these miniSTR markers allowed LR > 1000 values to be obtained in kinship cases with incomplete families whose results had not been significant when using commercial kits. In conclusion, a database with Argentine population frequencies from these 12 miniSTR markers may be very useful in adding supplementary information for the forensic genetic laboratory.

Screening for acetylcholinesterase inhibitory activity in plant extracts from Argentina

Plants are a potential source of bioactive compounds and offer a promising strategy for the treatment of neurological disorders such as Alzheimer's disease. The inhibitory effect of 73 native and naturalized plants collected from the central region of Argentina on acetylcholinesterase (AChE) was tested using microplate and TLC assays after solvent fractionation of complete ethanol extracts obtained from the plants. Organic fractions obtained from extracts of Achyrocline tomentosa (Asteraceae), Eupatorium viscidum (Asteraceae), Ruprechtia apetala (Polygonaceae) Trichocline reptans (Asteraceae) and Zanthoxylum coco (Rutaceae) presented strong inhibition of AChE (higher than 80%) at 1 mg/mL, with R. apetala and T. reptans being the most potent, showing complete inhibition of the enzyme. Their IC(50) values were 0.0779 and 0.1118 mg/mL, respectively. Aqueous fractions did not show any inhibitory activity on the enzyme. These results suggest that the most effective extracts deserve further investigation with the aim of obtaining new molecules for the treatment of neurodegenerative disorders.

Effect of post-fire defoliation on growth of two native grasses in the Caldenal, Argentina

Plant growth in semiarid rangelands may be affect - ed by time grazing is excluded during the post-fire regeneration period. The objective of this field work was to study the effect of post-fire defoliation at different phenological stages (vegetative (early-season defoliation) and internode elongation (late-season defoliation)) on growth of Piptochaetium napostaense and Poa ligu- laris, two very important perennial native grasses in the temperate semi-arid region of central Argentina (Caldenal). In general, the post-fire defoliation treatments did not affect the number of green leaves on tillers of P. napostaense. Early-season post-fire defoliation generally reduced the number of green leaves on tillers of P. ligularis in comparison to those in control plants. Late-season defoliation, however, usually increased the number of green leaves on tillers of P. ligularis. Nevertheless, very few significant (p 0.05) than values on non-defoliated plants, respectively. Immediately after early- and late-season defo- liation treatments, relative growth rates for tiller height and total green length were reduced (p<0.05) on plants of both species with respect to control plants. Our results suggest that a one-year-period without severe defoliations after fire would be at least necessary for not risking the persistence of these perennial grasses in the Calde- nal community.

Hepatitis C and HIV coinfection in central region of Argentina: prevalence, genotype characterization and risk factors

This is the first study reporting the epidemiological and molecular characterization of HCV/HIV coinfection in the central region of Argentina. Cross-sectional, epidemiological study (2003-2004). multivariate logistic regression analysis. The incidence of HCV/HIV coinfection was 12.3%. HCV genotype 1 was the most prevalent (73%). Intravenous drug use was the main independent risk factor for acquiring HCV infection. However, an alternative route (sexual) for viral transmission was suggested. These results underscore the potential public health impact of HCV/HIV coinfection in our region.

A new serotype 14 variant of the pneumococcal Spain9V-3 international clone detected in the central region of Argentina

The penicillin-resistant Spain(9V)-3 clone of Streptococcus pneumoniae is widespread and presents different serotype variants originating from recombination of the capsular genes. In this work, the genetic relatedness of 29 invasive pneumococci isolated from the central region of Argentina (Cordoba, Buenos Aires, Santa Fe and La Pampa provinces) was assessed by multilocus sequence typing (MLST). All of the penicillin-non-susceptible isolates studied (21/29) belonged to a serotype 14 variant of the Spain(9V)-3 clone. This clone was predominant, suggesting that it was responsible for the penicillin resistance spread in this region. Interestingly, this serotype 14 variant (named Cordoba S14V) could be differentiated from the European one by its pbp1a gene, suggesting a different recombinational replacement of the capsular genes. The putative recombination sites were analysed, resulting in the proximal crossover point being clearly localized in the spr0309 gene, with the distal site restricted to the recU gene, confirming a different recombination event. Analysis of the dexB, cpsB, aliA and pbp1a genes from these strains showed a high similarity with the corresponding genes of the Spain(14)-5 clone, suggesting that the capsular genes were provided by this international clone. Analysis of the genetic polymorphisms of the pbp1a (nt 1473-1922) and spr0309 (nt 1-790) genes is proposed as an epidemiological tool to help recognize the Cordoba S14V of the Spain(9V)-3 clone. On the other hand, BOX-repeat-based PCR and MLST analyses of serotype 14 strains revealed a divergent epidemiology of the Cordoba S14V, suggesting a non-recent dissemination in the paediatric population. It is suggested that this molecular epidemiology work will be a reference for monitoring the evolution of S14Vs of Spain(9V)-3, the emergence of new clones and the impact of pneumococcal vaccination programmes in Argentina.

Trace Element Profile of a Wild Edible Mushroom (Suillus granulatus)

Seventeen elements, Al, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, P, Pb, V, and Zn (macroelements and trace elements) were investigated by Atomic Spectrometries on a particular wild edible mushroom collected in the central region of Argentina during 2 different years in the same season. The metal content profile in Suillus granulatus samples is given. The found quantities of Na, K, Ca, Mg, Fe, P, V, and Al were 0.40, 10.84, 0.48, 0.30, 0.57, 4.24, 0.18, and 1.23 g/kg dry weight, respectively. The levels of Li, Cu, Zn, Cd, Co, Ni, Cr, and Mn were 0.98, 23.02, 22.30, 0.26, 0.16, 1.17, 0.90, and 28.75 mg/kg dry weight, respectively. Pb was not detected at the investigated levels. The results indicate that the levels of metals in the analyzed samples are not considered to be a health risk. In order to demonstrate the validity of our method, a recovery study was performed with acceptable results.

Shear Wave Velocity of a Compacted Clayey Silt

Abstract Loess deposit covers an extensive area in the central region of Argentina. Improvement of the stress-strain behavior of loess in the field usually includes compaction. In practice, in situ shear wave velocity is suggested as an alternative to control compaction density of loess. In this work, specimens of loess were compacted in the laboratory by means of the Standard Proctor Test at different moisture contents. After compaction, the moisture content of the specimens was varied by the wetting or drying processes. Matric suction was measured. The specimens were subjected to isotropic compression tests and shear wave velocity was measured by means of bender elements. The present study allows us to evaluate the influence of density, water content, confining pressure, and the different soil structures obtained during compaction, on the measured shear wave velocity of the compacted loess. It was observed that although shear wave velocity depends on compaction density, under certain circumstances, wave velocity may be mainly controlled by soil structure and suction forces. A simple relationship was proposed to approach the observed experimental trends.

Field surveys for potential ozone bioindicator plant species in Argentina

In Argentina no historical or present programs exist specifically assessing ecosystem health with respect to photochemical air pollution, although phytotoxic concentrations of near-ground ozone have been documented in recent years. Here we report our preliminary findings on field observations of ozone-like injury found in natural plant populations and agroecosystems late in the 2005 growing season in the Southern Hemisphere. Several possible ozone bioindicator plants which have not been previously documented were observed to exhibit foliar symptoms consistent with ozone-induced injury. Based on these results we intend to expand field surveys and complete the screening process for injury confirmation of the plant species described here. For this and future research we will be using controlled chamber studies based in the US. Continuous monitoring of tropospheric ozone does not currently take place in the region of central Argentina. The combined evidence provided by intermittent air quality sampling and the presence of ozone-like injury to vegetation indicates the need to establish air quality and ozone biomonitoring networks in this region.

Patterns leading to extreme events in Argentina: partial and generalized frosts

AbstractThis paper studies the atmospheric circulation associated with frosts in the central region of Argentina with the objective of improving the prediction capacity for these events. Frosts are selected according to a spatial principle, which takes into consideration those events affecting an area above 25% of the weather stations located in the region known as Wet Pampas. Partial frosts (PF, less than 75% of the stations) and generalized frosts (GF, above 75% of the stations) constitute two different groups: one of them given by PF + GF and the other one only by the PFs. The analysis comprises the period between 1961 and 1990, where two extremes are selected: those years with a number of frosts one standard deviation above and below the mean (+σ and − σ respectively). In each extreme group (i.e. PF + GF + σ and − σ; PF + σ and − σ), the average number of frosts varies according to the different periods of the year. Therefore, the following periods—selected independently—are studied: Annual of frosts (from April through October), seasonal (from May through September and from June through August), and each of the involved months individually.The mean circulation patterns analyzed from the composites of different meteorological variables explain the temperature anomalies observed in the region under study. In this way, the extreme occurrence of frosts is a result of the prevailing circulation during the different periods under consideration. Within each group (PF + GF and PF), the composites of the extremes + σ and − σ show opposite anomaly patterns for the different periods. Results for + σ(−σ) are distinguished by negative (positive) temperature and humidity anomalies in the Wet Pampas for the composites of PF + GF and PF. At low levels, the wind anomalies show the prevalence of winds from the south (north) in the southern section of the continent. At upper levels, this pattern is accompanied by anomalies of the prevailing westerly (easterly) wind for PF + GF and PF. This means a subtropical jet over South America more (less) intense than normal is associated with a higher (lower) frequency of frost occurrence in the seasonal composites and the Annual.However, there are variations in wind anomalies at 250 hPa within the same extreme + σ(−σ) when comparing the groups' PF with the previously studied group (formed only by the GF). Composites of group GF + σ showed a maximum anomaly of the westerly zonal wind located at the jet entrance region into South America, over the Andes. On the other hand, the composites for PF + σ show a component from the northwest located leeward the Andes, extending toward the southeast up to the Atlantic Ocean. The same anomaly for the extreme − σ extends from the north of Argentina up to tropical latitudes, and it is more intense for groups PF + GF and PF than for group GF.Additionally, an analysis of the daily evolution of PF events during winters' GF + σ shows that the PFs are caused by a cyclonic anomaly moving toward the east of the continent, causing cold air advection from the south. The same analysis for the GFs shows an anticyclonic anomaly dominating the southern area of South America, i.e. the anticyclogenesis that causes the GFs does not occur in the PFs. Copyright © 2007 Royal Meteorological Society

Effect of Local Land Use on Populations of a Disease Vector Planthopper

Abstract Delphacodes kuscheli (Hemiptera: Delphacidae) is the vector of maize rough dwarf virus that affects maize production in the central region of Argentina. The spatial abundance pattern and body morphology of the insect vector were studied during the spring and summer of 1999 and 2000 in endemic and nonendemic areas affected by this virus. An estimation of insect density was obtained from high sticky traps (6 m high) placed at nine sampling sites along a 500-km transect that crossed the main maize production area in Argentina. Host patches were detected, and their areas were measured using Landsat 5 Thematic Mapper (TM) imagery from the region to be studied. Population phenology of the individuals collected in the sampling sites was compared using multivariate analysis of morphometric variables. The land use estimated from Landsat 5 TM images varied according to the different sites and years. Areas with similar proportion of winter pastures, winter cereals, and perennial pastures were grouped togeth...

Infestation of Rural Houses by &lt;I&gt;Triatoma Infestans&lt;/I&gt; (Hemiptera: Reduviidae) in Southern Area of Gran Chaco in Argentina

The impact of control activities against Triatoma infestans (Klug) (Hemiptera: Reduviidae) in South America has a marked contrast within and outside the Gran Chaco region. Development of a geographic information system, as part of an improvement in control program activities, allowed analysis of the spatial pattern of house infestations by T. infestans before and after house spraying with deltamethrin in the San Martin Department (an arid Chaco region of central Argentina). The overall peridomestic infestation index decreased from 48.2 to 28.2% after insecticide application. House infestation was spatially clustered in regions with low or high infestation levels that were located east and southwest of the department, respectively. This pattern was detected both before and after the insecticide application. Three environmental variables calculated from a temporal series of MODIS imagery (average of night temperature, maximum of day temperature, and temporal variation of vegetation index) were capable of correctly discriminating 96% of the places belonging to either high or low house infestation observed after the insecticide application.

Energy-efficient housing for low-income students in a highly variable environment of central Argentina

Socio-economic, educational and environmental reasons have driven the building of energy-efficient dwellings for low-income students in University of La Pampa. The buildings are located in the central region of Argentina (35° 70′ of South latitude), an area of warm temperate climate. Energy conservation devices, passive solar heating, natural ventilation and solar protection were the main strategies of design. The resulting design comprised three blocks of housing with a useful floor area of 900 m 2. Two bedrooms, a dining room and essential services make up each house. Solar gains through transparent areas to the North are provided for all main spaces. Northern shading devices and metallic pergolas protect all windows in summer. In spite of high external temperature variability, the simulated performance during the design stage showed a remarkable internal thermal stability. The thermal and energy monitoring started in September 1999 and had two phases: (a) under real conditions of use and (b) during student's summer holidays (when the buildings were not inhabited). The results from the monitoring process suggest that interpretations about the building behaviour cannot be restricted to constructive issues. Useful inferences cannot be done from design and building technology only. The thermal behaviour was the result of construction, non-construction factors like dwellers habits, and their interaction. Energy saving in heating during the winter season was around 50%.

Population genetic analysis of 15 autosomal STRs loci in the central region of Argentina

Allele frequencies, together with some parameters of forensic interest, for 15 STRs included in the Powerplex-16 System (CSF1PO, D3S1358, D5S818, D7S820, D8S1179, D13S317, D16S539, D18S51, D21S11, FGA, Penta D, Penta E, TH01, TPOX and VWA) were estimated from a sample set of 1368 unrelated individuals from three of the most densely populated provinces of Argentina. No deviations from Hardy–Weinberg equilibrium were observed using the Bonferroni correction for the number of loci analyzed. Comparative analyses between our population data and that of other Argentinean databases previously published are presented and discussed. The most informative loci in our data set is the Penta E Loci with discrimination power larger than 0.98 and typical paternity index larger than 4.3. Our results demonstrate that these loci are robust since different laboratories and sample sets provided highly consistent results. This observation underscores the usefulness of these markers systems for human identification and parentage testing.

Development and validation of a Biotic Index for evaluation of environmental quality in the central region of Argentina

The Suquia River (Cordoba, Argentina) has become an important issue because it flows into Mar Chiquita Lake, one of the largest saline lakes in the world. This water body, together with the expansive swamps of the Dulce River on the northern shore and the mouth of Suquia and Xanaes River, is considered one of the most important wetlands in Argentina in terms of biodiversity in a range of freshwater to very saline environments. Nevertheless, the presence of densely populated urban settlements and the increasing environmental impact due to anthropogenic activities characterize the central and lower sections of Suquia River Basin. Fishes are particularly affected and change their distribution and abundance as a consequence of the environmental deterioration. We collected information on fish fauna to develop and validate a Biotic Index to assess degradation of the Suquia River Basin. We classified fish species according to their sensitiveness or tolerance to environmental degradation, based on their distribution and abundance variations along a water quality gradient in order to design a Biotic Index for Suquia River Basin. The set of metrics used in the Biotic Index calculation was conformed by: the abundance of Astyanax eigenmanniorum, Rineloricaria catamarcensis, Gambusia affinis and Cnesterodon decemmacultus, the proportion of sensitive species richness, and the proportion of tolerant species richness. They clearly distinguished between the impaired and referenced sites. We demonstrated that it is possible to use fish as indicators of water quality in Cordoba Province (central part of Argentina) in order to carry out rapid and relatively inexpensive monitoring and conservation programs. The application of this Biotic Index showed that fish assemblages reflect the watershed conditions and are sensitive to changes in water quality across the environmental gradient.

Molecular evidence of HTLV-1 intrafamilial transmission in a non-endemic area in Argentina

In the North of Argentina, an endemic area for HTLV-1, intrafamilial transmission of this virus has been observed. The HTLV-1 status in 13 family members of a seropositive blood donor from the central region of Argentina (non-endemic area) was investigated. According to serological and molecular assays, four members of this family (the blood donor, the husband, a son, and a daughter-in-law) proved to be HTLV-1 positive. LTR, tax, and env sequences from the provirus infecting the family members were identical. This strongly suggests the intrafamilial transmission of the virus. This study demonstrated intrafamilial transmission of HTLV-1 in a non-endemic area of Argentina.

Prevalence of diabetes, obesity, hypertension and hyperlipidemia in the central area of Argentina

There is little information available about the prevalence of chronic metabolic diseases in many Latin American countries. Between 1995 and 1998, studies on the prevalence of obesity, hypertension, hyperlipidemia and diabetes were carried out in four cities located in central Argentina: Dean Funes, Oncativo, Pehuajo and Venado Tuerto. The data provided by these surveys are reanalysed here in order to determine prevalence of obesity, hypertension, hyperlipidemia and diabetes using new epidemiological criteria. Representative samples of the population, based on a multistage probabilistic sampling design, were taken from each of the four cities. The sample size was calculated to obtain a precision of 4% for the prevalence assessment. The subjects included were aged 20 years and over. Standardization of the prevalence rates used the entire study sample as the reference population. Age-standardised prevalence rates for the cities ranged between 22.4% and 30.8% for obesity, 27.9% and 43.6% for hypertension, 24.2% and 36.4% for hyperlipidemia, and 6.5% and 7.7% for diabetes mellitus. All these prevalences increased with age. 58.1% of the obese subjects and 51.2% of the diabetic subjects had hypertension, while 43.2% of the obese subjects and 52.8% of the diabetic subjects had hyperlipidemia. While the prevalence of diabetes mellitus was between 6% and 8%, the prevalence of obesity was close to 26% and hypertension and hyperlipidemia affected one third of the population. These data can be considered as indicative of the prevalences of these four diseases in the population aged 20 years and over, in the central region of Argentina.