Bat Population Dynamics: An Individual-based Model Approach

Temperate zone bats are subject to serious energetic constraints due to their high surface area to volume relations, the cost of temperature regulation, the high metabolic cost of flight, and the seasonality of their resources. To my knowledge, there are no individual-based mathematical models for any bat species. The model developed here for a female bat is primarily based on life history and energetics. It describes the growth of an individual female bat using a system of differential equations modeling the dynamics of two main compartments: storage (lipids) and structure (proteins and carbohydrates). The model is parameterized for the little brown bat, Myotis lucifugus, because of information available on energy budgets and changes in body mass throughout its life history. However, with appropriate modifications the conceptualization might be applied to other species of bats with similar life histories. The dynamic estimates of daily energy budgets resulting from the model reasonably compare to previous estimates obtained through different methodologies. Sensitivity analysis using statistical screening design techniques identifies the individual parameters driving the model output and indicates the individual characteristics that might play an important role in survival, reproduction, and consequently in population dynamics. The individual model is used to test hypotheses related to strategies used by temperate bats to meet their energy demands. A complete corroboration of the model is not possible due to the lack of a data set independent of that used to construct and calibrate the model. The individual model is integrated into a structured population model. Characteristics of the individuals determine the structure and, subsequently the dynamics of the population. This methodology uses and integrates the information on bat biology and physiology that has been collected primarily at the individual level. Survival and reproductive rates estimated from simulated populations under varying density dependence are comparable to those reported in the literature for natural populations of M. lucifugus. The population model provides insight into possible regulatory mechanisms of bat population sizes and dynamics of survival and extinction. A better understanding of population dynamics can assist in the development of management techniques and conservation strategies, and to investigate stress effects

First palynologic record of the Cretaceous La Yesera Formation (Salta Group), northwestern Argentina

Thirty-four taxa were documented from six palynologically productive samples of the La Yesera Formation (Brealito and Don Bartolo Members) in the Pucará locality (Salta Province, northwestern Argentina). In the Brealito Member, aquatic species (mainly freshwater algae) dominate the palynofl ora, while terrestrial species are represented by trilete spores (mainly Anemiaceae) and gymnosperm pollen grains. In the Don Bartolo Member, Classopollis spp. dominate most of the assemblages, trilete Anemiaceae spores constitute half of the total counts in one of the assemblages and a unique angiosperm species (Tricolpites variabilis) was found in two assemblages. Ephedra-type pollen grains (three genera and six species) appear in both members, although in low abundance. The results support previous sedimentology studies that indicate a perennial lake environment at the time of deposition of the Brealito Member, with evidence for dry seasonality in the Don Bartolo Member. The inferred regional paleoclimate is subtropical with arid conditions. Considering the stratigraphic ranges of selected species and the sedimentology data, an Albian/Cenomanian age is suggested for the unit.Trinta e quatro táxons foram registrados a partir de seis amostras palinológicas provenientes da Formação La Yesera (membros Brealito e Don Bartolo), na localidade Pucará, Província de Salta, noroeste da Argentina. No Membro Brealito, predominam as espécies aquáticas, principalmente de algas de água doce; as espécies terrestres estão representadas por esporos triletes, principalmente de Anemiaceae e por grãos de pólen de gimnospermas. No Membro Don Bartolo, os grãos de pólen Classopollis spp. dominam a maioria das assembleias, embora numa das amostras, metade das contagens totais é constituída por esporos triletes de Anemiaceae e, uma única espécie de angiospermas (Tricolpites variabilis) foi encontrada em duas assembleias. Grãos de pólen do tipo Ephedra, com três gêneros e seis espécies, aparecem em baixa abundância em ambos os membros. Estes resultados corroboram estudos sedimentológicos anteriores e indicam ambiente lacustre perene, no momento da deposição do Membro Brealito, com evidência de sazonalidade seca para a Membro Don Bartolo. O paleoclima regional inferido é subtropical árido. Considerando os intervalos estratigráfi cos de espécies selecionadas e os dados sedimentológicos, é sugerida idade Albiano/Cenomaniano para a unidade estudada.Fil: Narvaez, Paula Liliana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Pramparo, Mercedes Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Sabino García, Ignacio Federico. Tecpetrol S. A.; Argentin

Bloodstream form pre-adaptation to the tsetse fly in Trypanosoma brucei

African trypanosomes are sustained in the bloodstream of their mammalian hosts by their extreme capacity for antigenic variation. However, for life cycle progression, trypanosomes also must generate transmission stages called stumpy forms that are pre-adapted to survive when taken up during the bloodmeal of the disease vector, tsetse flies. These stumpy forms are rather different to the proliferative slender forms that maintain the bloodstream parasitaemia. Firstly, they are non proliferative and morphologically distinct, secondly, they show particular sensitivity to environmental cues that signal entry to the tsetse fly and, thirdly, they are relatively robust such that they survive the changes in temperature, pH and proteolytic environment encountered within the tsetse midgut. These characteristics require regulated changes in gene expression to pre-adapt the parasite and the use of environmental sensing mechanisms, both of which allow the rapid initiation of differentiation to tsetse midgut procyclic forms upon transmission. Interestingly, the generation of stumpy forms is also regulated and periodic in the mammalian blood, this being governed by a density-sensing mechanism whereby a parasite-derived signal drives cell cycle arrest and cellular development both to optimise transmission and to prevent uncontrolled parasite multiplication overwhelming the host.In this review we detail recent developments in our understanding of the molecular mechanisms that underpin the production of stumpy forms in the mammalian bloodstream and their signal perception pathways both in the mammalian bloodstream and upon entry into the tsetse fly. These discoveries are discussed in the context of conserved eukaryotic signalling and differentiation mechanisms. Further, their potential to act as targets for therapeutic strategies that disrupt parasite development either in the mammalian bloodstream or upon their transmission to tsetse flies is also discussed

Inestabilidad del desarrollo en estructuras craneo-faciales de poblaciones humanas sudamericanas

Diversos factores genéticos y ambientales pueden actuar sobre los mecanismos que amortiguan el efecto de perturbaciones aleatorias durante el desarrollo, resultando en un aumento de la inestabilidad del desarrollo (ID) y de la variación a nivel individual. El objetivo de este trabajo es analizar el grado y el patrón de asimetría fluctuante (AF) en el cráneo, como una medida de ID, en poblaciones con distinto tipo de subsistencia. Asimismo, se evalúa la existencia de diferencias entre la base, la bóveda y el esqueleto facial. Se relevaron landmarks tridimensionales sagitales y bilaterales en 109 cráneos de Chubut, San Juan y SO de Pampa. El método de Superposición Procrustes Generalizado fue usado para extraer los componentes simétrico y asimétrico de la forma. Los análisis preliminares indicaron que el error de medición y la asimetría direccional dan cuenta de un porcentaje reducido de la variación total, mientras que la AF explica entre el 10 y el 15% de la misma. La magnitud de AF –estimada como la distancia Procrustes entre las configuraciones originales y sus imágenes reflejadas– de la bóveda y la región facial resultó mayor en San Juan, mientras que la base no presentó diferencias entre las muestras. Los patrones de forma del componente asimétrico indican que la muestra de Chubut se diferencia en la base y la cara, mientras que la de San Juan se diferencia en la bóveda. En resumen, los resultados obtenidos sugieren variación modular en la ID del cráneo y diferencias entre las muestras analizadas.Regulatory mechanisms acting on the effect of stochastic perturbations during development can be modulated by diverse environmental and genetic factors, resulting in increased developmental instability (DI) and individual variation. It has been suggested that subsistence-related ecological changes could have significantly influenced craniofacial morphology of South American aboriginal populations. In this paper, the magnitude and pattern of fluctuating asymmetry, used as a DI measure, are compared among the samples with different subsistence strategies and among 3 craniofacial modules. Midline and bilateral 3D landmarks were recorded in 109 skulls from Chubut, San Juan and SW of the Pampean region. The Generalized Procrustes Superimposition method was used to extract the symmetric and asymmetric components of shape. Preliminary analyses show that measurement error and directional asymmetry account for a reduced amount of total variation, while FA explains 10 to 15% of it. FA magnitude –estimated as the Procrustes distances between the original configurations and their reflections– found in the vault and facial region was higher for San Juan sample, while the cranial base did not show any differences among samples. Shape patterns in the asymmetric component show that Chubut sample is different from the others as regards cranial base and facial configurations, while San Juan is different in relation to vault. Results suggest modular variation in skull DI and differences among the analyzed samples.Fil: Lotto, Federico Pablo. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; ArgentinaFil: Gonzalez, Paula Natalia. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico CONICET- La Plata. Instituto de Genética Veterinaria "Ing. Fernando Noel Dulout". Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Instituto de Genética Veterinaria; Argentin

Phlorotannin Extracts from Fucales Characterized by HPLC-DAD-ESI-MSn: Approaches to Hyaluronidase Inhibitory Capacity and Antioxidant Properties

Purified phlorotannin extracts from four brown seaweeds (Cystoseira nodicaulis (Withering) M. Roberts, Cystoseira tamariscifolia (Hudson) Papenfuss, Cystoseira usneoides (Linnaeus) M. Roberts and Fucus spiralis Linnaeus), were characterized by HPLC-DAD-ESI-MSn . Fucophloroethol, fucodiphloroethol, fucotriphloroethol, 7-phloroeckol, phlorofucofuroeckol and bieckol/dieckol were identified. The antioxidant activity and the hyaluronidase (HAase) inhibitory capacity exhibited by the extracts were also assessed. A correlation between the extracts activity and their chemical composition was established. F. spiralis, the species presenting higher molecular weight phlorotannins, generally displayed the strongest lipid peroxidation inhibitory activity (IC50 = 2.32 mg/mL dry weight) and the strongest HAase inhibitory capacity (IC50 = 0.73 mg/mL dry weight). As for superoxide radical scavenging, C. nodicaulis was the most efficient species (IC50 = 0.93 mg/mL dry weight), followed by F. spiralis (IC50 = 1.30 mg/mL dry weight). These results show that purified phlorotannin extracts have potent capabilities for preventing and slowing down the skin aging process, which is mainly associated with free radical damage and with the reduction of hyaluronic acid concentration, characteristic of the process.info:eu-repo/semantics/publishedVersio

El movimiento en materia de derechos humanos y la existencia de los tipos raciales en la biología del siglo XX

En este trabajo se pretende establecer una relación entre algunos de los abordajes presentes en la biología durante la segunda mitad del siglo XX los cuales se han centrado en el estudio de las razas y en dicho movimiento social. Éste último, en general, se caracterizó por asumir la existencia de razas queriendo disolver la jerarquía entre las mismas -jerarquía preestablecida en los siglos anteriores-. En este sentido veremos cómo el movimiento en materia de derechos humanos de mediados del siglo XX, moduló algunos de los experimentos de la biología de este núsmo siglo, que se interrogan acerca de la existencia de los tipos raciales. En general debemos reconocer dos nociones de raza. Por un lado, se presentan las definiciones estrictamente biológicas y, por otro lado, se han dado algunos abordajes que parecen incluidos en su diferenciación no sólo elementos naturales sino también rasgos socioculturales que denotan identidades y valoración del otro, denominadas razas 'folk', las cuales no poseen un sustento biológico (Pighucci y Kaplan, 2003)