Nueve de Julio, Argentina
Nueve de Julio, Argentina

The National University of Chilecito is an Argentine national university situated in the city of Chilecito, La Rioja. The institution was established on December 16, 2002, on the Chilecito campus of the National University of La Rioja. It maintains schools of Law, Engineering, Licentiate, Technology, and Education. Wikipedia.

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Varela R.O.,Institute Ecologia | Varela R.O.,National University of Chilecito | Albornoz P.L.,Institute Morfologia Vegetal | Albornoz P.L.,National University of Tucuman
Revista de Biologia Tropical | Year: 2013

Seed biology is a relevant aspect of tropical forests because it is central to the understanding of processes of plant establishment, succession and natural regeneration. Anadenanthera colub-rina var. cebil is a timber tree from South America that produces large seeds with thin weak teguments, which is uncommon among legumes. This study describes the morphology and anatomy of the seed coat, the viability, imbibition, and germination in this species. Seeds used during the essays came from 10 trees that grow naturally in Horco Molle, province of Tucumán, Argentina. Seed morphology was described from a sample of 20 units. The seed coat surface was examined with a scanning electron microscope. Transverse sections of hydrated and non-hydrated seeds were employed to describe the histological structure of the seed coat. Hydration, viability and germination experiments were performed under laboratory controlled conditions; and the experimental design consisted of 10 replicas of 10 seeds each. Viability and germination tests were conducted using freshly fallen seeds and seeds stored for five months. Morphologically the seeds of A. colubrina var. cebil are circular to subcircular, laterally compressed, smooth, bright brown and have a horseshoe fissure line (=pleurogram) on both sides. The seed coat comprises five tissue layers and a double (external and internal) cuticle. The outer cuticle (on the epidermis) is smooth and interrupted by microcracks and pores of variable depth. The epidermis consists of macroesclereids with non-lignified secondary walls. This layer is separated from the underlying ones during seed hydration. The other layers of internal tissues are comprised of osteosclereids, parenchyma, osteo-sclereids, and macrosclereids. The percentage of viable seeds was 93%, decreasing to 75% in seeds with five months old. Seed mass increased 76% after the first eight hours of hydration. Germination percentage was 75% after 76 hours. Germination of seeds stored for five months decreased to 12%. The results showed that seeds of A. colubrina var. cebil are highly permeable and germinate directly without a dormant period.

Saggese M.D.,Western University of Health Sciences | Roesler I.,University of Buenos Aires | Marano C.F.,National University of Chilecito
Journal of Raptor Research | Year: 2014

The migratory subspecies of the "American" Osprey (Pandion haliaetus carolinensis) breeds across most of North America. Most of these Ospreys winter north of the equator, although significant numbers travel farther south, reaching Argentina. The number of Osprey sightings in Argentina has increased since the first review of their status in this country. We analyzed records of Osprey migration and distribution in Argentina from 1993 to 2008. We found that Ospreys occur year-round in Argentina, with a higher concentration in spring to summer (1 October to 31 March). Our data confirmed that in northern and northeastern Argentina, Ospreys use river systems and their major tributaries, and in central and northwestern regions, they commonly frequent reservoirs. The apparent increase in the number of Osprey records in Argentina in the last decades may result from an actual population increase but may also reflect a larger number of observers. Recent records suggest that Osprey should be considered a regular visitor to northern Argentina. We confirm the importance of northeastern rivers, and central and northwestern reservoirs as wintering areas. Argentina has been noted as an important wintering area for many migratory birds, but has been underestimated as a wintering area for Osprey. © 2014 The Raptor Research Foundation, Inc.

Cherbiy-Hoffmann S.U.,CONICET | Cherbiy-Hoffmann S.U.,National University of Chilecito | Hall A.J.,University of Buenos Aires | Searles P.S.,CONICET | Rousseaux M.C.,CONICET
Scientia Horticulturae | Year: 2015

Shading for short periods during potentially critical phenological phases can improve our understanding of the processes underlying the reductions in crop performance when solar radiation is limiting in high density orchards. Our objective was to evaluate the effects of three separate 30 day-long shade periods imposed during fruit set (FS), endocarp sclerification (ES), and early oil accumulation (OA) on some oil yield determinants and components in olive. Four shading levels (3, 20, 40, and 70% of incident photosynthetically active radiation; PAR) were applied in each period using shade cloths that surrounded one-half of large individual trees. Individual fruit dry weight, oil concentration (%) on a dry weight basis, and non-fruiting branch growth were determined at the end of each shading period, 45 days after their completion, and at the end of the season. The previously shaded- and the unshaded-halves of each tree were also harvested at the end of the season to obtain fruit number and oil yield for each half-tree. Individual fruit dry weight and oil concentration at the end of all three shading periods were decreased by shading due to reduced absolute rates of fruit growth and oil accumulation, respectively. However, at final harvest, there were no statistically significant treatment differences in individual fruit weight. By contrast, a small reduction in oil concentration persisted in the fruit from trees subjected to heavy shading during the OA period. Oil yield per half-tree at end of the season was decreased by shading applied during FS and OA periods, principally due to decreases in fruit number and oil concentration, respectively. Final oil yield was not affected by shading during the ES period. Elongation of non-fruiting branches was only decreased by shading during the early spring FS period, when vegetative growth was somewhat more sensitive to shading than fruit growth. Lastly, no consistent response of return bloom to the shading periods was detected the following spring. Our results suggest that the FS period when fruit number is defined and the OA period are more critical for determining final oil yield than the ES period. This information could provide guidance for the design of more effective management strategies in high density orchards where shading can play a key role. © 2015 Elsevier B.V.

Ortiz P.E.,National University of Tucuman | Ortiz P.E.,CONICET | Madozzo Jaen M.C.,National University of Tucuman | Jayat J.P.,National University of Tucuman | Jayat J.P.,National University of Chilecito
Journal of Arid Environments | Year: 2012

The understanding of the Holocene climatic fluctuations through the study of micromammal sequences can help to know the current environmental dynamic in arid lands. This is relevant because of the accelerated transformation that these environments are undergoing. We report the first stratified micromammal assemblage from the Monte desert on Northwestern Argentina, which span the last two millennia. We studied 11 700 cranial remains accumulated by owls's trophic activities, representing 16 species (MNI  5031). The assemblage composition is consistent with the species found in the area today, being the dominant Phyllotis xanthopygus, Eligmodontia spp., and Calomys musculinus. Relative frequencies and diversity show slight variations throughout the sequence, suggesting environmental stability. However, minor changes for several species indicate small-scale variations. We infer climatic conditions similar to those of the present for the period of 1600-1300 yBP, wetter conditions for 1000-600 yBP, and a return to xeric conditions up until the present. This reconstruction agrees with previous interpretations regarding global climatic dynamics, as those involving the Medieval Warm Period and the Little Ice Age. Since there are no areas potentially affected by agricultural activities within the owl's hunting area, the fluctuations are interpreted as primarily the result of changes in climatic conditions. © 2011 Elsevier Ltd.

Juri M.J.D.,National University of Tucuman | Juri M.J.D.,National University of Chilecito | Zaidenberg M.,Coordinacion Nacional de Control de Vectores | Santana M.,National University of Tucuman
Parasitology Research | Year: 2013

The efficacy of an ultralow volume formulation (ULV) and fumigant canister, containing both permethrin and pyriproxyfen, was compared with that of standard permethrin applications in a field assay conducted in Banda del Río Salí, Tucumán (north-western Argentina). Five treatment areas were established: first area was sprayed with a ULV formulation of 10 % permethrin, a second area was treated using a fumigant canister containing 10 % permethrin and 3 % pyriproxyfen, the third area was sprayed with a ULV formulation of 10 % permethrin and 3 % pyriproxyfen, the fourth area with ULV formulation of 10 % permethrin using a portable aerosol generator and the fifth area was a left untreated area. Immature and adult Aedes aegypti individuals placed in containers and sentinel cages were positioned within the treated and control areas. The effects of treatment and time on larval, pupal and adult survival were tested. We also investigated the effects of treatment and time on the numbers of larval and pupal deaths, on the proportion of larvae that metamorphosed into pupae and adults, and on the proportion of dead adults. Larval A. aegypti survivorship in 250 mL containers revealed a significant treatment effect and significant treatment × time interaction 2 and 24 h after the application of the ULV treatment with 10 % permethrin using the portable aerosol generator. The number of dead larvae in 20 L containers differed significantly by treatment and by time. ULV treatment with 10 % permethrin and 10 % permethrin plus 3 % pyriproxyfen using the cold fogger truck mount ULV resulted in the greatest numbers of dead larvae; most larvae died 2 weeks after application. Adult A. aegypti mortality in all treatments did not differ significantly 2 and 24 h after application. In addition, we found no significant differences in adult mortality between cages exposed at 3 m and those at 6 m from the ULV application line. However, there was a significant difference in adult mortality between the 10 % permethrin treatment applied with cold fogger truck mount ULV and that applied using the portable aerosol generator (P < 0.001). The larval index known as Breteau index (BI) was higher before treatment than after treatment in different areas. After the treatments, the lowest value of BI was observed in the area treated with the fumigant canister formulation, and a long-lasting effect was observed with the formulation of 10 % permethrin and 3 % pyriproxyfen. © 2013 Springer-Verlag Berlin Heidelberg.

Pelegrin N.,CONICET | Chani J.M.,National University of Chilecito | Echevarria A.L.,Institute Vertebrados Fundacion Miguel Lillo | Bucher E.H.,CONICET
Acta Oecologica | Year: 2013

Lizards partition resources in three main niche dimensions: time, space and food. Activity time and microhabitat use are strongly influenced by thermal environment, and may differ between species according to thermal requirements and tolerance. As thermal characteristics are influenced by habitat structure, microhabitat use and activity of lizards can change in disturbed habitats. We compared activity and microhabitat use of two abundant lizard species of the Semi-arid Chaco of Argentina between a restored and a highly degraded Chaco forest, to determine how habitat degradation affects lizard segregation in time and space, hypothesizing that as activity and microhabitat use of lizards are related to habitat structure, activity and microhabitat use of individual species can be altered in degraded habitats, thus changing segregation patterns between them. Activity changed from an overlapped pattern in a restored forest to a segregated pattern in a degraded forest. A similar trend was observed for microhabitat use, although to a less extent. No correlation was found between air temperature and lizard activity, but lizard activity varied along the day and among sites. Contrary to what was believed, activity patterns of neotropical diurnal lizards are not fixed, but affected by multiple factors related to habitat structure and possibly to interspecific interactions. Changes in activity patterns and microhabitat use in degraded forests may have important implications when analyzing the effects of climate change on lizard species, due to synergistic effects.© 2013 Elsevier Masson SAS.

Dantur Juri M.J.,National University of Tucuman | Dantur Juri M.J.,National University of Chilecito | Veggiani Aybar C.A.,National University of Tucuman | Ortega E.S.,National University of Tucuman | And 2 more authors.
Malaria Journal | Year: 2013

A case of co-infection with Plasmodium vivax and Mansonella ozzardi was detected in a blood sample from a person who had shown symptoms of malaria and lived in a city that was close to the Argentina/Bolivia border. The case was detected during a random revision of thick and thin smears from patients diagnosed with malaria from various towns and cities located in north-western Argentina between 1983 and 2001. Trophozoites of P. vivax were observed in the thin blood smear along with M. ozzardi microfilaria (larval form), which presented a long, slender, pointed anucleate tail and the absence of the sheath. This last characteristic is shared with Mansonella perstans, Mansonella streptocerca and Onchocerca volvulus. More rigorously controlled studies to detect other co-infection cases in the area as well as the possibility of importation from Bolivia into Argentina are currently ongoing. The relationship between the malaria parasite and microfilaria, the potential effect of malaria treatment on the development of M. ozzardi, and the possible impact of this microfilaria on the immunity of a person against P. vivax are all still unknown. This contribution constitutes a point of focus for future studies involving the interaction between the parasites and the potential risk that humans are exposed to. © 2013 Dantur Juri et al.; licensee BioMed Central Ltd.

Romano E.,National University of Tucuman | Raschi A.B.,National University of Tucuman | Benavente A.,National University of Tucuman | Benavente A.,National University of Chilecito | Brandan S.A.,National University of Tucuman
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2011

We have studied and characterized the structural and vibrational properties of 2R-(-)-6-hydroxytremetone, isolated from Xenophyllum poposum (Phil.) by infrared and Raman spectroscopy in the solid phase. The density functional theory (DFT) method together with Pople's basis set show that two stable molecules for the compound have been theoretically determined in the gas phase and that both conformations are present in the solid phase, as was experimentally observed. The harmonic vibrational wavenumbers for the optimized geometry were calculated at B3LYP/6-31G*and B3LYP/6-311++G** levels. For a complete assignment of the vibrational spectra, DFT calculations were combined with Pulay's Scaled Quantum Mechanics Force Field (SQMFF) methodology in order to fit the theoretical wavenumber values to the experimental ones. Then, a complete assignment of all the observed bands in the infrared spectrum for the compound was performed. The natural bond orbital (NBO) study reveals the characteristics of the electronic delocalization of the two structures, while the corresponding topological properties of electronic charge density are analyzed by employing Bader's Atoms in the Molecules theory (AIM). © 2011 Elsevier B.V. All rights reserved.

Ortiz P.E.,CONICET | Jayat J.P.,National University of Chilecito
Mammalia | Year: 2012

Reithrodon auritus is a living sigmodontine with one of the broader temporal records, from the lower Pliocene of Argentina. Its populations in northwestern Argentina are today found patchily and restricted to five high-elevation and isolated localities in open areas of highland grasslands vegetation (at >3000 m). During the Pleistocene and early Holocene, R. auritus would have had a broader range, reaching lower altitudes everywhere and being one of the dominant small mammal species in some fossil localities. In this note, we summarize the known Pleistocene and early Holocene fossil record of R. auritus in northwestern Argentina, provide new paleontological sites for the species, and make comments concerning the paleoenvironmental implications of its presence at such lower altitudes. The paleontological evidence indicates that during the Pleistocene and early Holocene, R. auritus inhabited around 1000 m below their current altitudinal distribution in the eastern Andean ranges, with populations clearly more abundant than today. The fossils of R. auritus are indicative of colder and perhaps more xeric paleoenvironmental conditions, characterized by open areas with sparse grassy vegetation as those developed today around 3000 m elevation. Copyright © 2011-2012 by Walter de Gruyter.

Cherbiy-Hoffmann S.U.,CONICET | Cherbiy-Hoffmann S.U.,National University of Chilecito | Searles P.S.,CONICET | Hall A.J.,University of Buenos Aires | Rousseaux M.C.,CONICET
Scientia Horticulturae | Year: 2012

Olive cultivation has expanded considerably beyond the Mediterranean Basin to include new areas in the Southern Hemisphere. This study evaluated the response functions of yield determinants and components to photosynthetically active radiation (PAR) in a large olive hedgerow (cv. 'Arbequina') in subtropical Argentina, and assessed whether mechanical pruning altered these relationships. Mechanical pruning was applied at the end of the winter dormant period to the east side and top of hedgerows oriented North-South, while the other side was left unpruned. The PAR distribution and leaf density at different positions within the hedgerow were measured over the two subsequent growing seasons with inflorescence density, fruit set, fruit density, individual fruit dry weight, and oil content (%) being assessed the second growing season. Hedgerow size increased substantially during the first season, especially on the pruned side and top, reducing transmitted PAR in much of the canopy to less than 20% of full Sun incident PAR values above the orchard. The relationship between leaf density (and thus number of axillary buds) and PAR was bilinear for the canopy positions within the unpruned side with a threshold of about 15% of full Sun PAR, above which leaf density did not increase. No relationships between leaf density and PAR were found within the pruned side and top. In contrast, inflorescence density exhibited a threshold of 18% of PAR for canopy positions within both the pruned and unpruned sides, although no relationship was apparent for the pruned top. Neither fruit set nor yield component relationships with PAR were affected by pruning. Fruit set had a linear response to PAR for the observed range of PAR values within the hedgerow (approx. 0-50% of full Sun). Individual fruit dry weight and oil content (%) also showed linear responses to PAR. The results suggest that oil production in large olive hedgerows (height. × width) is limited by low solar radiation within the canopy, and that substantial vegetative growth triggered by mechanical pruning may be an important contributor to this limitation under current management practices in subtropical climates. © 2012 Elsevier B.V.

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