Activity of digestive enzymes in chicken's small intestine and caeca: Effect of dietary protein and carbohydrate content
Ciminari, María E.; Caviedes Vidal, Enrique Juan Raul; Chediack, Juan Gabriel
Digestion is a mediating factor between the animals and their environment, one of the variables related to the efficiency in extracting energy from nutrients is rate of hydrolysis. Phylogenetical and functional hypothesis has been proposed linking dietary flexibility and enzyme lability. Species belong to Parvclass Galloanserae, studied until now, did not modulate aminopeptidase-N activity but they did modulate disaccharidases activities. Additionally, peptide hydrolysis has been demonstrated in avian caeca, but not in chickens. Finally, dietary proteins are essential for chicken growth in the first stages of development, but little information is available in chickens beyond 42 days of life. Chickens beyond that age were fed for 15 days either a high protein (DHP = 49.72% protein and 11.92% carbohydrates) or a high starch diet (DHS = 52.82% carbohydrates and 10.49% protein). Aminopeptidase-N, maltase and sucrase, were assessed in chicken’s small intestines and caeca. Body mass of DHP birds was 37.5% higher than body mass of DHS birds, at the end of the trial. Aminopeptidase-N and sucrase did not change, but maltase exhibited higher activity in DHS than in DHP birds. The lack of aminopeptidase-N modulation and its relatively high activity in caeca, together with a modulation of maltase, contribute and give apparent support to the functional hypothesis. Surprisingly, a high quantity of protein resulted important for growth in chickens after 42 days of life. Also it is important to notice that a casein diet has been demonstrated as a high digestible meal for chickens, so the last data may be of interest for poultry industry.
Distribution and effects of tree leaf litter on vegetation composition and biomass in a forest-grassland ecotone
Loydi, Alejandro; Lohse, Kerstin; Otte, Annette; Donath, Tobias W.; Eckstein, R. Lutz
Aims: After abandonment of grasslands, secondary succession leads to the invasion by woody species. This process begins with the accumulation of tree litter in the forest–grassland ecotone. Our objectives were to determine the relationships between litter amounts and vegetation composition and cover along natural forest–grassland ecotones and to experimentally study the initial effects of tree litter accumulation on grassland vegetation and on microsite conditions. Methods: We established 11 transects varying from 12 to 15 m in length in different forest–grassland ecotones in the Lahn-Dill highlands, Germany, and measured the mass and cover of tree litter and the cover and composition of vegetation at five sequential positions along each transect by using 1 m2 plots with five replications. In a field experiment, we established plots subjected to different litter amounts (0, 200 and 600g m−2) and evaluated changes in grassland vegetation, soil temperature and soil nutrient availability below the litter layer. Important Findings: Tree litter amounts decrease from 650 to 65g m−2 across the forest–grassland ecotone. Vegetation changed from shrubs and annual species (adapted to more stressful conditions) in the forests edge to grasses, rosettes and hemirosette species (with higher competitive abilities) in the grassland. These anthropogenic forest–grassland ecotones showed abrupt edges, and the two adjacent ecosystems were characterized by different species pools and functional groups. In the field experiment, the presence of a litter layer reduced vegetation biomass and cover; the species richness was only reduced in the treatment with high litter (600g m−2). Additionally, adding litter on top of vegetation also reduced thermal amplitude and the number of frost days, while increasing the availability of some nutrients, such as nitrogen and aluminium, the latter being an indicator of soil acidification. Adding a tree litter layer of 600g m−2 in grassland areas had strong effects on the composition and diversity of grassland vegetation by reducing the cover of several key grassland species. In, or near, forest edges, litter accumulation rapidly changes established vegetation, microsite conditions and soil nutrients.
Neo y paleoornitología virtual
Tambussi, Claudia Patricia; Degrange, Federico Javier; Tirao, German Alfredo
La visualización y análisis de los fósiles asistido por computadoras ha revolucionado el estudio de los organismos extintos. Técnicas novedosas permiten caracterizar los restos en tres dimensiones y acceder a detalles sin precedentes. Esto ha permitido a los paleontólogos ganar importantes conocimientos sobre la anatomía, el desarrollo, la función y hasta la conservación. Las reconstrucciones digitales se pueden utilizar en análisis funcionales y en la puesta a prueba rigurosa de hipótesis sobre la paleobiología de los organismos extintos. Estos enfoques están transformando nuestra comprensión de la vida en el pasado y también de los organismos vivientes en general. El empleo de técnicas no invasivas permite la captura de grandes cantidades de datos útiles sin dañar los especímenes que se están estudiando. Debido a que los datos digitales se pueden compartir de forma instantánea y global, equipos de científicos pueden trabajar en paralelo, acelerando el ritmo de las investigaciones. En este trabajo se ejemplifican casos en los cuales a partir de modelos virtuales se pueden abordar problemas morfológicos en aves.; Visualization and analysis of fossils assisted by computers have revolutionized the study of extinct organisms. Innovative techniques allow to characterize the remains in three dimensions with unprecedented detail, allowing paleontologists to gain important knowledge about anatomy, development, function and even conservation. Digital reconstructions can be used in functional analysis and rigorous testing of hypotheses on the paleobiology of extinct organisms. These approaches are transforming our understanding about life in the past and also of living organisms in general. The use of noninvasive techniques enables capturing large amounts of data without damaging the specimens under study. As digital data can be shared instantly and globally, teams of scientists can work in parallel, accelerating research time. In this paper, cases in which virtual models were used to assess morphological problems are shown.
Expeditious photochemical reaction towards the preparation of substituted chroman-4-ones
Iguchi, Daniela; Erra Balsells, Rosa; Bonesi, Sergio Mauricio
A facile photochemical preparation of 5-, 6- and 7-substituted chroman-4-ones from aryl 3-methyl-2-butenoate esters is described. The two-phase base-catalyzed method relies upon two consecutive processes in one-pot reaction through a photo-Fries rearrangement and a based-catalyzed intramolecular oxa-Michael addition to afford the desired products.
Analytical characterization and purification of a commercial extract of enzymes: a case study
Llerena Suster, Carlos Rafael; Briand, Laura Estefania; Morcelle del Valle, Susana Raquel
This paper presents a rational strategy to identify and quantify the components of a commercial extract of the lipase B of Candida antarctica that can be extended to the analytical investigation of other crude extracts of enzymes. These information provided the fundamental knowledge for the development of a methodology to obtain highly pure and catalytically active CALB enzyme. The commercial extract Lipozyme® was subjected to a series of analytical techniques that allowed determining the presence of a non-soluble fraction; nucleic acids; benzoate and sorbate species and a mixture of three proteins. Particularly, it is worth noticing that the Bradford assay using CALB as standard instead of BSA proved to be a more reliable and accurate methodology to quantify the protein content of the assayed enzymatic samples. Size exclusion chromatography coupled with anionic exchange chromatography using a non conventional, easy to remove buffer system such as ammonia-ammonium acetate afforded a sample that retains 47% of the proteins (being CALB the only enzymatic component of the purified sample) with an hydrolytic activity higher than the crude extract.
Seedling response of Nothofagus species to N and P: linking plant architecture to N/P ratio and resorption proficiency
Agüero, Mariana; Puntieri, Javier Guido; Mazzarino, Maria Julia; Grosfeld, Javier Edgardo; Barroetaveña, Carolina
Previous studies on mature forests of NW Argentinean Patagonia indicated that N is the main growth-limiting nutrient in most dominant tree species, while P limitation is uncommon, despite the soils’ volcanic origin. This pattern was inferred from leaf N/P ratios and resorption proficiencies, but has not been experimentally tested. We conducted a greenhouse trial with seedlings of two deciduous species of high timber quality, Nothofagus nervosa and N. obliqua, and soils characteristic of each species. Seedlings were fertilized with three levels of N (100, 200 and 400 mg kg−1 soil) with or without the concurrent application of a single P dose (60 mg kg−1 soil) during their second growing season. Response variables were morphological descriptors of shoot and root growth, N and P concentrations in green and senescent leaves and ectomycorrhizal infection. Both species were primarily limited by N: the addition of N resulted in higher shoot and root masses, an increased number of nodes, taller stems and greater basal and root diameters, while no effect of P was found. N/P ratios in green leaves and N and P resorption proficiencies indicate that with increased N availability P can become a secondary-limiting nutrient for N. nervosa. This was accompanied by the maintenance of ectomycorrhizal infection and mass allocation to roots in this species. The steep growth response of N. obliqua to N addition may signal a strong competitive capacity of this species when growing in soils of high N availability.
Strong temporal consistency in the individual foraging behaviour of Imperial Shags Phalacrocorax atriceps
Harris, Sabrina; Raya Rey, Andrea Nélida; Zavalaga, Carlos; Quintana, Flavio Roberto
Individual consistency in foraging behaviour can generate behavioural variability within populations and may, ultimately, lead to species diversification. However, individual-based long-term behavioural studies are particularly scarce in seabird species. Between 2008 and 2011, breeding Imperial Shags Phalacrocorax atriceps at the Punta León colony, Argentina, were tracked with GPS devices to evaluate behavioural consistency during their foraging trips. Within a breeding season, individuals were highly consistent in the maximum distances they reached from the shore and the colony, as well as in the time invested in flight and diving across consecutive days during early chick rearing. In addition, each individual had its specific foraging area distinct from the foraging area of other individuals. Comparing between early and late chick rearing in the same season, individuals were consistent, to a lesser degree, in the maximum distance they reached from the colony and the shore, increasing in consistency later on in the season. Within the season, females were more consistent than males in the maximum distance they moved from the colony and the shore, the sexes segregated in their foraging areas and individual females were segregated from one another. Twenty-eight individuals tracked in different breeding seasons were marginally consistent in their trip durations and maximum distance reached from shore across seasons. Among seasons, foraging locations differed between sexes and among individual females. Individuals from this colony exhibited consistency over time in several aspects of foraging behaviour, which may be due to a combination of individual characteristics such as learning abilities, breeding experience or health, as well as targeted prey type and stability of the environment at this location.
Antitumoral, Antihypertensive, Antimicrobial, and Antioxidant Effects of an Octanuclear Copper(II)-Telmisartan Complex with an Hydrophobic Nanometer Hole
Islas, María Soledad; Martínez Medina, Juan José; López Tévez, Libertad Leonor; Rojo, Teófilo; Lezama, Luis; Griera Merino, Mercedes; Calleros, Laura; Cortés, María Alicia; Rodriguez Puyol, Manuel; Echeverría, Gustavo Alberto; Piro, Oscar Enrique; Ferrer, Evelina Gloria; Williams, Patricia Ana María
A new Cu(II) complex with the antihypertensive drug telmisartan, [Cu8Tlm16].24H2O (CuTlm), was synthesized and characterized by elemental analysis and electronic, FTIR, Raman and EPR spectroscopy. The crystal structure (at 120 K) was solved by X-ray diffraction methods. The octanuclear complex is a hydrate of but otherwise isostructural to the previously reported [Cu8Tlm16] complex. [Cu8Tlm16].24H2O crystallizes in the tetragonal P4/ncc space group with a=b=47.335(1), c=30.894(3) Å, Z=4 molecules per unit cell giving a macro-cyclic ring with a double helical structure. The Cu(II) ions are in a distorted bi-pyramidal environment with a somewhat twisted square basis, cis-coordinated at their core N2O2 basis to two carboxylate oxygen and to two terminal benzimidazole nitrogen atoms. Cu8Tlm16 has a toroidal-like shape with a hydrophobic nanometer hole and their crystal packing defines nano-channels that extend along the crystal c-axis. Several biological activities of the complex and the parent ligand were examined in vitro. The antioxidant measurements indicate that the complex behaves as a superoxide dismutase mimics with improved superoxide scavenger power as compared with native sartan. The capacity of telmisartan and its copper complex to expand human mesangial cells (previously contracted by angiotensin II treatment) is similar to each other. The antihypertensive effect of the compounds is attributed to the strongest binding affinity to angiotensin II type 1 receptor and not to the antioxidant effects. The cytotoxic activity of the complex and that of its components was determined against lung cancer cell line A549 and three prostate cancer cell lines (LNCaP, PC-3 and DU 145). The complex displays some inhibitory effect on the A549 line and a high viability decrease on the LNCaP (androgen-sensitive) line. From flow cytometric analysis it was established an apoptotic mechanism for the latter cell line. Telmisartan and CuTlm show antibacterial and antifungal activities in various strains and CuTlm displays improved activity against the Stafilococcus aureus strain as compared with unbounded copper(II).
BIOFRAG: A new database for analysing BIOdiversity responses to forest FRAGmentation
Pfeifer, Marion; Lefebvre, Veronique; Gardner, Toby A.; Arroyo Rodríguez, Víctor; Baeten, Lander; Banks Leite, Cristina; Barlow, Jos; Betts, Matthew G.; Brunet, Joerg; Cerezo Blandón, Alexis Mauricio; Cisneros, Laura M.; Collard, Stuart; D´Cruze, Neil; Da Silva Motta, Catarina; Duguay, Stephanie; Eggermont, Hilde; Eigenbrod, Félix; Hadley, Adam S.; Hanson, Thor R.; Hawes, Joseph E.; Heartsill Scalley, Tamara; Klingbeil, Brian T.; Kolb, Annette; Kormann, Urs; Kumar, Sunil; Lachat, Thibault; Lakeman Fraser, Poppy; Lantschner, María Victoria; Laurance, William F.; Leal, Inara R.; Lens, Luc; Marsh, Charles J.; Medina Rangel, Guido F.; Melles, Stephanie; Mezger, Dirk; Oldekop, Johan A.; Overal , Williams L.; Owen, Charlotte; Peres, Carlos A.; Phalan, Ben; Pidgeon, Anna Michle; Pilia, Oriana; Possingham, Hugh P.; Possingham, Max L.; Raheem, Dinarzarde C.; Ribeiro, Danilo B.; Ribeiro Neto, Jose D.; Robinson, Douglas W.; Robinson, Richard; Rytwinski, Trina; Scherber, Christoph; Slade, Eleanor M.; Somarriba, Eduardo; Stouffer, Philip C.; Struebig, Matthew J.; Tylianakis, Jason M.; Teja, Tscharntke; Tyre, Andrew J.; Urbina Cardona, Jose N.; Vasconcelos, Heraldo L.; Wearn, Oliver; Wells, Konstans; Willig, Michael R.; Wood, Eric; Young, Richard P.; Bradley, Andrew V.; Ewers, Robert M.
Habitat fragmentation studies are producing inconsistent and complex results across which it is nearly impossible to synthesise. Consistent analytical techniques can be applied to primary datasets, if stored in a flexible database that allows simple data retrieval for subsequent analyses. Method: We developed a relational database linking data collected in the field to taxonomic nomenclature, spatial and temporal plot attributes and further environmental variables (e.g. information on biogeographic region. Typical field assessments include measures of biological variables (e.g. presence, abundance, ground cover) of one species or a set of species linked to a set of plots in fragments of a forested landscape. Conclusion: The database currently holds records of 5792 unique species sampled in 52 landscapes in six of eight biogeographic regions: mammals 173, birds 1101, herpetofauna 284, insects 2317, other arthropods: 48, plants 1804, snails 65. Most species are found in one or two landscapes, but some are found in four. Using the huge amount of primary data on biodiversity response to fragmentation becomes increasingly important as anthropogenic pressures from high population growth and land demands are increasing. This database can be queried to extract data for subsequent analyses of the biological response to forest fragmentation with new metrics that can integrate across the components of fragmented landscapes. Meta-analyses of findings based on consistent methods and metrics will be able to generalise over studies allowing inter-comparisons for unified answers. The database can thus help researchers in providing findings for analyses of trade-offs between land use benefits and impacts on biodiversity and to track performance of management for biodiversity conservation in human-modified landscapes.
Violencia y materialidad de la ficción. (Sobre la recepción de Django Unchained)
Pachilla, Pablo Nicolás
En este artículo se discuten los conceptos de "estetización de la violencia" y "glorificación de la violencia" a propósito de Django Unchained de Quentin Tarantino. Se apunta al carácter metaficcional de los films de dicho director, en los cuales el espectador se ve confrontado a sus propias fantasías sádicas, y se procura desligar la violencia presente en ellas de la noción de justicia, contraponiéndola de este modo a la muchedumbre de películas en las que el protagonista "apela al cielo", al decir lockeano, para hacer justicia por mano propia. Se contrastan asimismo dos tipos de violencia: aquella propia de la esclavitud, por un lado, y lo que el director llama "movie violence", por el otro.
¿Es realmente valiosa la igualdad política?
Garcia Valverde, Facundo
el objetivo de este artículo es defender el valor normativo de un principio de igualdad de oportunidades para influir políticamente en contra de un principio que las distribuya de manera desigual pero beneficiando a los peor situados. Para ello, se muestra que la influencia política es un bien de un tipo especial que permite rechazar la objeción de la nivelación hacia abajo y que la igualdad política, aunque pueda ser derrotada por consideraciones epistémicas, es absolutamente necesaria para criticar aspectos inequitativos de una distribución desigual.; el objetivo de este artículo es defender el valor normativo de un principio de igualdad de oportunidades para influir políticamente en contra de un principio que las distribuya de manera desigual pero beneficiando a los peor situados. Para ello, se muestra que la influencia política es un bien de un tipo especial que permite rechazar la objeción de la nivelación hacia abajo y que la igualdad política, aunque pueda ser derrotada por consideraciones epistémicas, es absolutamente necesaria para criticar aspectos inequitativos de una distribución desigual.
Las Dimensiones Morales de la Vida Colectiva: Exploraciones desde los Estudios Sociales de las Moralidades
Noel, Gabriel David
Ante un panorama en el cual la tematización de las dimensiones morales de la vida social ocupa un lugar quizás no central, pero si creciente y notorio en las agendas de la sociología y la antropología, el presente dossier se presenta como una invitación teórica y metodológica, pero sobre todo heurística, que procura mostrar a partir de experiencias concretas de investigación en ciencias sociales la productividad de interrogar y construir nuestros objetos desde un punto de vista que se sitúa en el terreno de las indagaciones sobre el lugar de la moral y lo moral en la vida social. El objeto de esta compilación no apunta específicamente a tematizar la moral como objeto de las ciencias sociales sino a mostrar a partir de trabajos concretos surgidos de experiencias de investigación qué es lo que permite y habilita el movilizar la moral como recurso teórico, como herramienta metodológica o como perspectiva de análisis.
Los docentes universitarios y su concepción sobre el aprendizaje, la autorregulación y la personalización educativa: Un análisis desde la teoría fundamentada
Daura, Florencia Teresita
Se presentan los resultados de una investigación en la que se efectuaron entrevistas semiestructuradas en profundidad a los docentes responsables de asignaturas del Ciclo Clínico de la carrera de Medicina que se dicta en una universidad privada y otra estatal. Los datos recogidos se analizaron a partir del modelo ofrecido por la teoría fundamentada (STRAUSS & CORBIN 1998) con el objeto de elaborar una interpretación sobre cuál es la concepción que los profesores poseen sobre tres conceptos que se consideran centrales en el proceso educativo: el aprendizaje, la capacidad autorreguladora y la personalización.
Palliative care staff perspectives: The challenges of end-of-life care on their professional practices and everyday lives
Luxardo, Natalia; Vindrola Padros, Cecilia; Tripodoro, Vilma
This article has 3 goals: To describe the attitudes and experiences of staff on end-of-life care treatment of dying persons, to examine how the staff view their terminally ill patients, and to gather professionals' opinions on how their experiences impact their daily lives. It is a qualitative research inquiry based on a constructivist-grounded theory design. The study subjects were professionals who were part of palliative care services in Buenos Aires city during 2012. A purposive sample of 30 personnel answered an open-ended questionnaire assessing attitudes and perceptions concerning end-of-life. The results showed the following: (a) "Good" deaths were considered those in which physical symptoms were dealt with, where the patient was surrounded or on good terms with family members, and where they were at peace with themselves, any unfinished business, or God. "Bad" deaths were believed to be those where the patient was physically uncomfortable, were within a conspiracy-silence atmosphere, and died alone. (b) The factors in common that staff members identified regarding deaths were the need for spiritual comfort, peace, and acceptance and the need for attaining a deep connection with others. (c) The unexpected issues identified among end-of-life trajectories were the varying attitudes that patients had regarding death. (d) The personal life of the staff was affected by being in charge of end-of-life care decision making.
Exploring trends in labor informality in Latin America, 1990-2010
Tornarolli, Leopoldo Horacio; Battistón, Diego Ezequiel; Gasparini, Leonardo Carlos; Gluzmann, Pablo Alfredo
Labor informality is a pervasive characteristic of the labor markets in Latin America, and a central issue in the public policy debate. This paper discusses the concept of labor informality and implements alternative definitions using microdata from around 300 national household surveys in all Latin American countries. The analysis covers two decades: while labor informality, defined as lack of social protection related to employment, remained with few changes in the 1990s, there is a discernible downward pattern during the 2000s in most countries. These movements reveal a counter-cyclical behavior of labor informality, that may be linked to segmentation in the labor market.
On the use of the double floating probe method to infer the difference between the electron and the heavy particles temperatures in an atmospheric pressure, vortex?stabilized nitrogen plasma jet
Prevosto, Leandro; Kelly, Hector Juan; Mancinelli, Beatriz Rosa
Sweeping double probe measurements in an atmospheric pressure direct current vortex-stabilized plasma jet are reported (plasma conditions: 100 A discharge current, N2 gas flow rate of 25 Nl/min, thoriated tungsten rod-type cathode, copper anode with 5 mm inner diameter). The interpretation of the double probe characteristic was based on a generalization of the standard double floating probe
formulae for non-uniform plasmas coupled to a non-equilibrium plasma composition model. Perturbations caused by the current to the probe together with collisional and thermal processes inside the probe perturbed region were taken into account. Radial values of the average electron and heavy particle temperatures as well as the electron density were obtained. The calculation of the temperature values did not require any specific assumption about a temperature relationship between different particle species. An electron temperature of 10 900 ± 900 K, a heavy particle temperature of 9300 ± 900 K, and an electron density of about 3.5 × 1022 m−3 were found at the jet centre at 3.5 mm downstream from the torch exit. Large deviations from kinetic equilibrium were found toward the outer border of the plasma jet. These results showed good agreement with those previously reported
by the authors by using a single probe technique. The calculations have shown that this method is particularly useful for studying spraying-type plasma torches perated at power levels of about 15 kW
"Escuchar el cuerpo y creer en eso": Exploraciones en torno a la noción de registro de sí en el marco de las medicinas alternativas (Buenos Aires, Argentina); Listen to your body and believe in that: Explorations of the notion of self-reflection in the context of alternative medicine (Buenos Aires, Argentina); “Escutar o corpo e acreditar nisso”: Explorações em torno à noção de autorreflexão no marco das medicinas alternativas (Buenos Aires, Argentina)
Bordes, Mariana Argentina
El artículo tiene como objetivo explorar un aspecto de la lógica del cuidado de la salud que se delinea en el universo de las medicinas alternativas, no-convencionales, o complementarias y alternativas, como las denomina la Organización Mundial de la Salud (OMS, 2002): el que pondera el registro de sí como una de las dimensiones de la eficacia terapéutica en sentido amplio. Cabe destacar que este trabajo se desprende de una investigación de tesis doctoral centrada en analizar la construcción de significados terapéuticos en el marco de una medicina alternativa en particular (la reflexología), la cual fue llevada adelante desde una perspectiva sociológica cualitativa.; The article aims to analyze one aspect of the logic of health care that is outlined in the universe of alternative, non-conventional, or complementary and alternative medicine, as the World Health Organization denominates them (WHO, 2002); we refer to the notion of selfreflection and self-knowledge as one of the dimensions of the therapeutic efficacy in a broad sense. It is worth noting that that this work is based on the research for a doctoral dissertation focused on analyzing the construction of therapeutic meanings within the framework of a particular form of alternative medicine (reflexology), which was carried out from a qualitative sociological perspective.; O artigo tem como objetivo explorar um aspecto da lógica do cuidado da saúde que se delineia no universo das medicinas alternativas, não convencionais, ou complementárias e alternativas, como denomina a Organização Mundial de Saúde (OMS, 2002): o que pondera a autorreflexão como uma das dimensões da eficácia terapêutica em sentido amplo. É importante destacar que este trabalho deriva-se uma pesquisa de tese doutoral centrada em analisar a construção de significados terapêuticos no marco de uma medicina alternativa em particular (a reflexologia), a qual foi levada adiante desde uma perspectiva sociológica qualitativa.
Morphometry and Relative Growth of Populations of Tanais dulongii (Audoin, 1826) (Tanaidacea: Tanaidae) in Pristine and Impacted Marine Environments of the Southwestern Atlantic
Rumbold, Carlos Enrique; Obenat, Sandra Mabel; Spivak, Eduardo Daniel
Life history strategies are closely related to environmental conditions and biotic and abiotic factors play a major role conditioning several traits as growth rates, sexual maturity, size and morphometric differences. We compare body dimensions, relative growth patterns, and size of sexual differentiation between populations of Tanais dulongii (Audoin, 1826) that live in two contrasting habitats in order to determine if they differ in life history traits. Some 900 individuals were collected (150 males, 150 females and 150 juveniles from each site) in a rocky shore with a lower anthropic impact (La Estafeta) and a polluted area (Mar del Plata Harbor) and thirteen body dimensions between sexes and environments were compared. Relative growth rates were determined establishing the relationship between total length (TL) and the rest of body dimensions with reduced major axis method (RMA). Regression slopes were employed to test the degree of isometry or allometry. MDS and SIMPER analyses were used to plot and identify morphometric differences between sexes and populations. TL and the rest of body dimensions were longer in La Estafeta than in Mar del Plata, and degree of sexual differentiation was larger in La Estafeta (ca. 3.5 mm) than in Mar del Plata (1.75 mm). RMA showed differences among sites: in Mar del Plata growth of most dimensions was positively allometric in adults, but in La Estafeta half of the measured dimensions had positive allometric growth for both sexes and half had isometric or negative allometric growth. Juveniles of both sites showed a positively allometric growth. MDS established a clear separation between sites and sexes. SIMPER showed that TL, cheliped length, cheliped width, and antennule peduncle length contributed most to differences between sexes, and TL (mainly) and the rest of variables (in minor degree) in the dissimilarities between sites. We believe that the differences observed between populations of T. dulongii are due to phenotypic plasticity in this species in response to environmental differences.
Inflammation in response to phytohemagglutinin injection in the Talas tuco-tuco (Ctenomys talarum): implications for the estimation of immunocompetence in natural populations of wild rodents
Merlo, Julieta; Cutrera, Ana Paula; Zenuto, Roxana Rita
The immunological variation in wild populations and its relation to life-history traits has recently become a central topic in the field of evolutionary biology, considering the critical contribution of immunity to an individual’s fitness. A common technique used by ecologists to estimate immunocompetence in wild populations is the phytohemagglutinin (PHA) – skin test. In this test, the degree of local swelling triggered by PHA is usually considered an estimate of T-lymphocyte activity, although there is an ongoing debate regarding this interpretation. Here, we coupled the PHA–skin test with a histological analysis to examine the temporal development of the cell-mediated response in the subterranean rodent Talas tuco-tuco (Ctenomys talarum Thomas, 1898). The inflammation response involved lymphocytes, neutrophils, eosinophils, and macrophages at the site of injection, achieving an increase of total leukocytes from 12 to 48 h after injection. However, the abundance of any of the leukocytes observed did not correlate with the degree of swelling at any time studied, suggesting that caution should be taken when interpreting the results of the PHA-induced swelling response. Particularly, the magnitude of macroscopic swelling should not be considered a priori as indicative of T-lymphocyte activity in wild-caught rodents. Our results highlight the importance of avoiding oversimplified approaches to measuring immunocompetence.
