1,389 research outputs found
Asymmetric distribution of primary cilia allocates satellite cells for self-renewal
Regeneration of vertebrate skeletal muscles requires satellite cells, a population of stem cells that are quiescent in normal conditions and
divide, differentiate, and self-renew upon activation triggered by exercise, injury, and degenerative diseases. Satellite cell self-renewal is
essential for long-term tissue homeostasis, and previous work has identified a number of external cues that control this process. However,
little is known of the possible intrinsic control mechanisms of satellite cell self-renewal. Here, we show that quiescent satellite cells harbor
a primary cilium, which is rapidly disassembled upon entry into the cell cycle. Contrasting with a commonly accepted belief, cilia reassembly
does not occur uniformly in cells exiting the cell cycle. We found that primary cilia reassemble preferentially in cells committed to
self-renew, and disruption of cilia reassembly causes a specific deficit in self-renewing satellite cells. These observations indicate that primary
cilia provide an intrinsic cue essential for satellite cell self-renewal
The dynamics of financial stability in complex networks
We address the problem of banking system resilience by applying
off-equilibrium statistical physics to a system of particles, representing the
economic agents, modelled according to the theoretical foundation of the
current banking regulation, the so called Merton-Vasicek model. Economic agents
are attracted to each other to exchange `economic energy', forming a network of
trades. When the capital level of one economic agent drops below a minimum, the
economic agent becomes insolvent. The insolvency of one single economic agent
affects the economic energy of all its neighbours which thus become susceptible
to insolvency, being able to trigger a chain of insolvencies (avalanche). We
show that the distribution of avalanche sizes follows a power-law whose
exponent depends on the minimum capital level. Furthermore, we present evidence
that under an increase in the minimum capital level, large crashes will be
avoided only if one assumes that agents will accept a drop in business levels,
while keeping their trading attitudes and policies unchanged. The alternative
assumption, that agents will try to restore their business levels, may lead to
the unexpected consequence that large crises occur with higher probability
Experimental conditions for microhabitat selection in terrestrial snails
Habitat selection by terrestrial snails, used as laboratory animals, is an important factor because it can alter growth rates often used as a good biological indicator, moreover of its productive meaning. As support to the studies in this field, different models from election of microhabitat based on the individual selection or derived from other questions as the availability or the accessibility of the habitat or patron of movement of the organism are reviewed. Finally two experimental designs used in invertebrates under laboratorial conditions for preference studies are considered.La selección de hábitat por los caracoles terrestres que se utilizan como animales de experimentación, es importante porque condiciona el crecimiento y éste, además de su importancia productiva, es un buen indicador en muchos estudios. Como apoyo a los estudios en este campo, se revisan diferentes modelos de elección de microhábitat en función de la selección del propio individuo o bien derivados de cuestiones en buena parte ajenas a él como la disponibilidad o accesibilidad del hábitat o el patrón de movimiento del organismo. Finalmente se plantean dos diseños experimentales adecuados para el estudio de preferencia en invertebrados bajo condiciones de laboratorio
Malacological diversity in Andalusia. Renewable resource
The aim of this study is the evaluation of malacological diversity in Andalusian region. It has been observed high heterogeneity in relation to distribution patters of snails. Terrestrial edible snail populations are grouped in zones in relation to spatial distribution and specie. Zone I is located in Sierra Morena and shows a low density level of the most commonly edible species (O. lactea, H. aspersa, T. pisana and E. vermiculata). Zone II is extended throughout La Campiña and Vega del Guadalquivir. This zone is widely populated by snails with great economically importance: O. lactea and T. pisana and H. aspersa with a smaller density. Zone III is located in Sierras Béticas and it is characterised by the presence of many endemic populations (O. lactea murcica, O. punctata, T. pisana arietina, T. subdentata helicella, C. nemoralis, I. gualtierianus gualtierianus, I. gualtierianus alonensis, I. gualtierianus guiraoanus, etc.). It is necessary to develop strategic plans in order to conserve the malacological diversity in Andalusia.El objetivo del estudio es la evaluación de la diversidad malacológica andaluza como base del aprovechamiento de un recurso genético de interés económico. Se zonifican las poblaciones de caracoles comestibles existentes en Andalucía en relación al número de especies y su distribución geográfica. Se observa elevada heterogeneidad que da lugar a la conformación de tres zonas diferenciadas, en las que aparecen fundamentalmente los géneros Otala, Theba, Cantareus, Iberus, Eobania, Cepaea, Pseudotachea y Sphincterochila. La Zona I comprende Sierra Morena y se caracteriza por una baja presencia de caracoles, asociados mayoritariamente a la presencia humana y representados por las especies más comunes (O. lactea, H. aspersa, T. pisana y E. vermiculata). La Zona II comprende la Campiña y Vega del Guadalquivir, donde aparecen las especies de mayor valor comercial: O. lactea y T. pisana, con gran distribución; y H. aspersa con menor presencia. Finalmente la Zona III, que se integra por las Sierras Béticas donde aparecen, junto con las especies anteriormente citadas, gran diversidad de taxones con elevada singularidad, debido a la existencia de un número importante de endemismos y poblaciones relictas (O. lactea murcica, O. punctata, T. pisana arietina, T. subdentata helicella, C. nemoralis, I. gualtierianus gualtierianus, I. gualtierianus alonensis, I. gualtierianus guiraoanus, etc.). La existencia de esta biodiversidad justifica la necesidad de adoptar acciones estratégicas y planes específicos de conservación que preserven este recurso de forma eficaz
l-Leucine supplemented whey protein. Dose–response effect on heart mTOR activation of sedentary and trained rats
AbstractThe aim of the study was to investigate the effect of leucine supplementation combined with exercise and whey protein in cardiac mTOR anabolic pathway. Ninety-six weanling male Wistar rats were divided into eight groups and fed diets containing either casein or WP plus increasing levels (0, 3, 4.5 and 6% of diet) of l-leucine for 30days. A parallel set of eight groups was exercised for comparison. Serum aspartate amino transferase, alanine aminotransferase, creatine kinase, lactate dehydrogenase and branched chain amino acids were determined by standard methods, and mammalian target of rapamycin (mTOR) and p70S6K by the Western blot analysis. Chronic l-leucine supplementation was capable of increasing both mTOR and p70S6K phosphorylation in the heart in a dose-dependent fashion, independent of the type of dietary protein in both groups, sedentary and exercised, but the exercise potentialized the activation of the anabolic pathway. The content of protein in heart increase with l-leucine supplementation and the heart mass relativized by body mass did not change. In conclusion, the combination of l-leucine and milk proteins (casein or whey protein) has the potential to increase the mTOR pathway in the cardiac muscle without increasing the heart mass. The novelty of this study is to show the effectiveness of a blend of leucine and whey protein as a viable alternative to maximize the activation of the anabolic pathway of cardiac muscle and that the exercise can improve this process
Effect of calcium carbonate addition to helix aspersa müller diet
In this paper is studied the effect of calcium carbonate addition to diet on growth, mortality rate and feed intake of snails Helix aspersa Müller during the juvenile stage under laboratory conditions. Two treatments have been tested; first one with 12.5 percent and second one with 22.5 percent of calcium carbonate. Five groups of 40 snails have been randomly assigned to each treatment. Results show significant (p<0.05) differences between both treatments; in the second one is obtained a higher growth and lower mortality rate; however there is no significant difference for dry matter intake.En el presente trabajo se estudia el efecto de la adición de carbonato de calcio a la dieta sobre el crecimiento, mortalidad y consumo del caracol Helix aspersa Müller durante la fase de alevinaje y en condiciones de laboratorio. Se plantean dos tratamientos; el I con 12,5 p.100 y el II con 22,5 p.100 de carbonato cálcico. A cada tratamiento se le asignan aleatoriamente cinco lotes de 40 animales. Los resultados muestran diferencias significativas (p<0,05) entre ambos tratamientos; obteniéndose con el tratamiento II mayor crecimiento y menor mortalidad; que no se aprecian diferencias significativas respecto al consumo de materia seca
Caracterización social y comercial de los sistemas ovinos y caprinos de la región noroeste de República Dominicana
A fin de estudiar los aspectos sociales y comerciales que caracterizan
al sistema de producción de ovinos y caprinos de la
región noroeste de República Dominicana, se muestrearon 94
explotaciones (24% de la población), aplicando el método de
encuesta directa mediante muestreo aleatorio estratificado con
asignación proporcional. Las explotaciones que conforman este
sistema ganadero son en un 82% familiares, con antigüedad en
torno a 16 ±1,3 años. El 93% de los propietarios son hombres,
con edad media de 51 ±1,2 años, el 63% ha iniciado estudios
primarios y 8% no ha realizado estudios. El régimen de tenencia
de tierra está relacionado al tipo de explotación según la especie
productiva (p<0,05); el 84% de las explotaciones caprinas se desarrollan
en tierras públicas y las explotaciones ovinas y mixtas
hacen mayor uso de terrenos privados. Para 53% de los propietarios
la producción de ovinos y caprinos constituye la actividad
principal y 78% de las explotaciones utiliza mano de obra
familiar. La comercialización se efectúa mediante canales largos
con los carniceros (70%), mientras el 14% de las explotaciones
vende directamente al consumidor. El sistema estudiado se caracteriza
por explotaciones familiares, cuyos propietarios presentan
edad avanzada, bajo nivel de formación, alta dependencia
de terrenos públicos y escasa participación activa del productor
en la comercialización. Esta situación limita el acceso al crédito
y la adopción e innovación tecnológica. Finalmente, se considera
que el fomento del asociacionismo podría ayudar a superar
estas restricciones.In order to study the social and commercial aspects that
characterize the sheep and goat cattle production systems in
the Northwestern region of the Dominican Republic, 94 farms
(24% of the population) were sampled, applying the direct
survey method through random sampling with proportional
weighting. The farms comprising this cattle system are 82%
family owned, with a standing of 16 ±1.3 years. Of the owners,
93% are men, with average age of 51 ±1.2 years; 63%
began primary schooling and 8% did not go to school. The
land ownership regime is related to the type of exploitation
according to the productive species (p<0.05); 84% of goat
farms are on public land, and sheep and mixed farms make a larger use of private lots. For 53% of the owners the production
of sheep and goats is their main activity and 75% of
the farms use family labor. Marketing is carried out through
long channels to butchers (70%), while 14% of the farms sell
directly to consumers. The system under study is characterized
by family farms whose owners are of advanced age, low
training level, with a high dependency on public land y meager
participation of the producer in marketing. This situation
limits access to credit, as well as technological adoption and
innovation. Finally, it is considered that the promotion of associations
could help overcome such restriction
Effect of humus supplement on growth, digestibility and nutritional efficiency of juvenile Helix aspersa snail
El humus es importante en la dieta de Helix aspersa y de otras
especies de caracoles comestibles aunque su contribución nutricional
es poco conocida. En el presente trabajo se evalúa el efecto
de un suplemento con humus sobre el crecimiento, eficiencia
nutricional y digestibilidad del caracol H. aspersa durante la fase
juvenil. El experimento se hizo en laboratorio usando un diseño
completamente al azar con dos tratamientos (dietas) con diez
repeticiones de veinte caracoles: dieta I, concentrado comercial
para gallinas ponedoras; dieta II, concentrado comercial para
gallinas ponedoras más un suplemento con humus comercial
de lombriz. Cuando los caracoles juveniles H. aspersa crecen
en presencia de humus lo consumen regularmente y aumentan
la velocidad de crecimiento (478.71±8.26 mg sin humus, dieta
I; 912.21±9.42 mg con humus, dieta II; p≤0.01). El humus
también aumenta la disponibilidad de los nutrientes orgánicos
de la dieta, mejorando la digestibilidad de la materia seca
(54.21±2.12% sin humus, dieta I; 80.13±1.37% con humus,
dieta II; p≤0.001), energía bruta (56.32±3.13% sin humus,
dieta I; 65.56±4.21% con humus, dieta II; p≤0.001), proteína
cruda (63.14±3.41% sin humus, dieta I; 74.56±2.82% con humus;
dieta II; p≤0.01), fibra detergente neutro (56.68±4.84%
sin humus, dieta I; 66.64±3.21% con humus, dieta II; p≤0.01)
y fibra detergente ácido (35.32±3.32% sin humus, dieta I;
47.42±2.13% con humus, dieta II; p≤0.001). Por tanto, se mejoró
la razón de conversión alimenticia (1.12±0.14 sin humus,
dieta I; 0.78±0.11 con humus, dieta II; p≤0.01) y la razón de
eficiencia proteica (6.40±0.09 sin humus, dieta I; 11.09±0.15
con humus, dieta II; p≤0.01).Humus is important in the diet of Helix aspersa and other
species of edible snails although its nutritional contribution is
not well known. In this study the effect of a humus supplement
on the growth, nutritional efficiency and digestibility of the
snail H. aspersa in its juvenile stage was evaluated. The
experiment was done under laboratory conditions using a
completely randomized design with two treatments (diets) with
ten replications of 20 snails: Diet I, commercial concentrate
for laying hens; Diet II, the same commercial concentrate plus
a commercial humus supplement for earthworms. When H.
aspersa juvenile snails grow in the presence of humus, they
feed regularly on the supplement and grow significantly faster
(478.71±8.26 mg without humus, diet I; 912.21±9.42 mg with
humus, diet II; p≤0.01). Humus also increases the availability
of the diet’s organic nutrients, improving digestibility of dry
matter (54.21±2.12% without humus, diet I; 80.13±1.37%
with humus, diet II; p≤0.001), raw energy (56.32±3.13%
without humus, diet I; 65.56±4.21% with humus, diet II;
p≤0.001), crude protein (63.14±3.41% without humus, diet I;
74.56±2.82% with humus; diet II; p≤0.01), neutral detergent
fiber (56.68±4.84% without humus, diet I; 66.64±3.21%
with humus, diet II; p≤0.01) and acidic detergent fiber
(35.32±3.32% without humus, diet I; 47.42±2.13% with
humus, diet II; p≤0.001). Therefore, the feed conversion ratio
was improved (1.12±0.14 without humus, diet I; 0.78±0.11
with humus, diet II; p≤0.01) and the protein efficiency ratio
(6.40±0.09 without humus, diet I; 11.09±0.15 with humus,
diet II; p≤0.01)
Commercial circuits of organic milk in seven spanish regions
A major concern for organic dairy farms is to develop specific commercial circuits who guarantee the flow of organic products to the consumers. Therefore, the commercial circuits for organic milk are analysed. Actually, 11.5 millon litres of organic milk are produced in Spain, of which 5% are commercialised by conventional milk. The rest is commercialised as an organic circuit with two differentiated channels. Firstly, the long channel that absorbed 70% of organic milk and displays a conventional structure. The average price perceived by litre of organic milk rise to 0.44 euros. Secondly, the short channel that receives 26% of production. The prices in this channel rise to an average of 1,66 euros/l.Un aspecto de suma importancia para la producción ecológica es el desarrollo de circuitos comerciales que garanticen el flujo de productos ecológicos a los consumidores. En el presente trabajo se analizan los canales comerciales de leche ecológica de vaca. Actualmente la producción de leche ecológica en España se estima en 11,5 millones de litros, de los que el 5% se comercializa como leche convencional. El 95% restante sigue un circuito ecológico con dos canales bien diferenciados. En primer lugar, un 70% de la leche ecológica se comercializa a través del canal largo, que presenta una estructura convencional. El precio medio percibido asciende a 0,44 euros por litro de leche ecológica, lo que supone un incremento del 30% respecto al precio de la leche convencional. En segundo lugar, el circuito corto, que absorbe el 26% de la leche ecológica e incrementa el precio percibido hasta 1,66 euros/l, que además repercute en la renta final del ganadero
ANALYSIS OF BUILDING MATERIALS BY SYNCHROTRON X-RAY IMAGING
Building materials have complex hierarchical microstructures. The largest components are coarse aggregates with dimensions larger than a few centimetres and the smallest ones are the calcium silicate hydrate (C-S-H) gel nanoparticles with sizes smaller than 5 nm. To fully understand the main properties of cement binders and optimize their performances, a sound description of their spatially-resolved contents is compulsory. Furthermore, cement manufacturing is responsible for about 7% of the anthropogenic CO2 emissions and hence, to decrease the CO2 footprint, in a sustainable and cost-effective way, is a top priority. To gain a deeper insight into the microstructures of building materials, synchrotron X-ray ptychographic nanotomography and absorption-based microtomography have been employed.
Here we will present three examples of our approach blending quantitative powder diffraction with synchrotron X-ray imaging. Firstly, we will show our comparative work on belite and Portland cement pastes cured at varying temperatures [1]. Synchrotron tomographic data taken at TOMCAT allowed understanding the different hydrating behaviour of both cements. Secondly, ptychographic nanotomographic data taken at cSAXS showed the hydration of CaAl2O4 with curing temperature [2]. Ptychographic data have permitted to characterise the conversion of the aluminate hydrates which is key for durability. The very good contrast in the electron density tomograms will be discussed as well as the porosity induced after the conversion reactions. Finally, we will report our work on Portland cements [3]. The densities and spatial distribution of calcium silicate hydrate (C-S-H) gel and amorphous iron-siliceous hydrogarnet components will be described.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech.
BIA2017-82391-R
UMA18-FEDERJA-09
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