720 research outputs found
Movement between crops and weeds: temporal refuges for aphidophagous insects in Central Chile
Villegas, CM (Villegas, Cinthya M.)[ 1 ] ; Verdugo, JA (Verdugo, Jaime A.)[ 1,3 ] ; Tapia, J (Tapia, Jaime)[ 2 ] ; Lavandero, B (Lavandero, Bias)[ 1 ].1 ] Univ Talca, Inst Biol Vegetal & Biotecnol, Talca, Chile.2 ] Univ Talca, Inst Quim Recursos Nat, Talca, ChileCrop edges have significant effects on populations of natural enemies, acting as source or sink habitats during the growing season. Previous observations have shown that coccinellid species are associated with thistle (Sylibum marianum (L.) Gaertn), a common exotic weed in the central valley of Chile. To determine whether thistles growing at crop edges act as a putative refuge for natural enemies, the seasonal relative abundance of aphidophagous coccinellids was estimated at 0, 10 and 25 m from the edges of three alfalfa fields. Mark-recapture studies were carried out using the trace element rubidium (Rb) to determine whether coccinellids moved between the edges and the alfalfa. The most common aphidophagous coccinellid species were Hippodamia convergens (63%), H. variegata (11%), Rhyzobius lophantae (4%) and Adalia angulifera (4%). In mid-November, the abundance of coccinellids at the edge of (0 m from the edge) the alfalfa plot increased compared to that at the center of the field (25 m from the edge), coinciding with a reduction in the population of aphids at all sampling points. Of the coccinellids captured at the thistle edge, 68% were marked with rubidium, suggesting movement of coccinellids from the alfalfa plot to the thistle growing at its edges. After the thistles were removed, coccinellids returned to the crop, as shown by the presence of marked coccinellids within the alfalfa fields at all three sampling distances. The results of this study suggest that thistles can act as a refuge for coccinellids when aphids are not available in the alfalfa fields
Volcanic sequence in Late Triassic – Jurassicsiliciclastic and evaporitic rocks from Galeana, NE Mexico
In northeastern Mexico, volcanic rocks interbedded with Late Triassic–Jurassic siliciclastic and evaporitic strata have been linked to magmatic arcs developed in the Pangea western margin during its initial phase of fragmentation. This work provides new petrographic and geochemical data for volcanism included in the El Alamar and Minas Viejas formations outcropping in the Galeana region. Andesitic dykes and sills (n= 10) in the El Alamar redbeds show SiO2= 47.5–59.1% and MgO= 1.2–4.2%, as well as a geochemical affinity to island arc magmas. This work represents the first report of this tectonic setting in the region. Geological and petrographic evidence suggest that this arc system likely developed after ~220 and before ~193Ma. Trachy-andesitic and rhyodacitic domes (n= 20) associated with the Minas Viejas gypsum-carbonates sequence show SiO2= 61.8–82.7% and MgO= 0.1–4.0% with a tectonic affinity to continental arc. A rhyodacite sample from this region has been dated by U-Pb in zircon, yielding an age of 149.4 ± 1.2Ma (n= 21), being the youngest age related to this arc. Finally, we propose a threestep model to explain the tectonic evolution from Late Triassic island arc to Jurassic continental arc system in the northeastern Mexico
Parámetros reproductivos en el ganado vacuno de raza retinta explotado en dehesa: edad al primer parto e intervalo entre partos
La mejora de los caracteres reproductivos es de vital importancia para maximizar esta rentabilidad de las explotaciones de vacuno de carne, especialmente en las razas explotadas en régimen extensivo, como es el caso de la raza Retinta. Dicho sistema supone condiciones adversas e incluso extremas para los animales, especialmente durante la fase de recría fase fundamental y a la que generalmente se presta escasa atención en estas explotaciones. El objetivo del presente trabaja fue, analizar la posible influencia de distintos factores, tanto ambientales como genéticos, sobre la edad al primer parto (EPP) y el intervalo entre partos (IPP). Para ello hemos contando con los registros reproductivos correspondientes al Núcleo de Control de Rendimientos de la Raza Retinta. Estos incluían 2.786 primeros partos y 11.197 intervalos entre partos, correspondientes a 3. 112 vacas. Según nuestros resultados la edad al primer parto del ganado vacuno de raza Retinta se ve afectada por los factores ganadería de nacimiento, campaña y época de nacimiento, y la interacción de los tres. Dentro de estos factores, el factor ganadería absorbió del 52 al 66% de la variabilidad de la edad al primer parto. Otro factor que resulto significativo fue el tipo de alimentación que recibe la ternera durante el periodo predestete. Así mismo nuestros resultados muestras que dentro del rango de EPP estudiadas, no existe influencia sobre las condiciones de crecimiento del ternero de ese primer parto ni de los posteriores, incluso las novillas que paren a edad temprana (dentro de unos límites fisiológicos), produjeron más terneros y más pesados durante su vida. En cuanto al periodo medio entre partos encontramos una fuerte relación con la ganadería, y con el efecto campaña ganadera, correspondiendo los intervalos más largos a aquellos años en los que aparece un notable período de sequía. Independientemente a este factor, se aprecia una evidente disminución del IPP en la última década. El valor medio obtenido está fuertemente influenciado por el sistema de cubrición seguido (paridera restringida o continua). Según nuestros resultados las ganaderías con temporada de cubrición continua presentan menores intervalos, aunque con bajas diferencias, lo cual puede ser refleja de un manejo reproductivo menos optimizado que las de paridera estacional
Characterization of a putative grapevine Zn transporter, VvZIP3, suggests its involvement in early reproductive development in Vitis vinifera L
Gonzalez, E (reprint author), Univ Talca, Inst Biol Vegetal & Biotecnol, Talca, Chile.Background: Zinc (Zn) deficiency is one of the most widespread mineral nutritional problems that affect normal development in plants. Because Zn cannot passively diffuse across cell membranes, it must be transported into intracellular compartments for all biological processes where Zn is required. Several members of the Zinc-regulated transporters, Iron-regulated transporter-like Protein (ZIP) gene family have been characterized in plants, and have shown to be involved in metal uptake and transport. This study describes the first putative Zn transporter in grapevine. Unravelling its function may explain an important symptom of Zn deficiency in grapevines, which is the production of clusters with fewer and usually smaller berries than normal.
Results: We identified and characterized a putative Zn transporter from berries of Vitis vinifera L., named VvZIP3. Compared to other members of the ZIP family identified in the Vitis vinifera L. genome, VvZIP3 is mainly expressed in reproductive tissue - specifically in developing flowers - which correlates with the high Zn accumulation in these organs. Contrary to this, the low expression of VvZIP3 in parthenocarpic berries shows a relationship with the lower Zn accumulation in this tissue than in normal seeded berries where its expression is induced by Zn. The predicted protein sequence indicates strong similarity with several members of the ZIP family from Arabidopsis thaliana and other species. Moreover, VvZIP3 complemented the growth defect of a yeast Zn-uptake mutant, ZHY3, and is localized in the plasma membrane of plant cells, suggesting that VvZIP3 has the function of a Zn uptake transporter.
Conclusions: Our results suggest that VvZIP3 encodes a putative plasma membrane Zn transporter protein member of the ZIP gene family that might play a role in Zn uptake and distribution during the early reproductive development in Vitis vinifera L., indicating that the availability of this micronutrient may be relevant for reproductive development
Activation of microglia in specific hypothalamic nuclei and the cerebellum of adult rats exposed to neonatal overnutrition
Much attention has been drawn to the possible involvement of hypothalamic inflammation in the pathogenesis of metabolic disorders, especially in response to a high-fat diet. Microglia, the macrophages of the central nervous system, can be activated by proinflammatory signals resulting in the local production of specific interleukins and cytokines, which in turn could exacerbate the pathogenic process. Because obesity itself is considered to be a state of chronic inflammation, we evaluated whether being overweight results in microglial activation in the hypothalamus of rats on a normal diet. Accordingly, we used a model of neonatal overnutrition that entailed adjustment of litter size at birth (small litters: four pups/dam versus normal litters: 12 pups/dam) and resulted in a 15% increase in bodyweight and increased circulating leptin levels at postnatal day 60. Rats that were overnourished during neonatal life had an increased number of activated microglia in specific hypothalamic areas such as the ventromedial hypothalamus, which is an important site for metabolic control. However, this effect was not confined to the hypothalamus because significant microglial activation was also observed in the cerebellar white matter. There was no change in circulating tumour necrosis factor (TNF) α levels or TNFα mRNA levels in either the hypothalamus or cerebellum. Interleukin (IL)6 protein levels were higher in both the hypothalamus and cerebellum, with no change in IL6 mRNA levels. Because circulating IL6 levels were elevated, this rise in central IL6 could be a result of increased uptake. Thus, activation of microglia occurs in adult rats exposed to neonatal overnutrition and a moderate increase in weight gain on a normal diet, possibly representing a secondary response to systemic inflammation. Moreover, this activation could result in local changes in specific hypothalamic nuclei that in turn further deregulate metabolic homeostasi
Impact of manufacturing tolerances on axial flux permanent magnet machines with ironless rotor core: a statistical approach
Axial Flux Permanent Magnet (AFPM) machines with ironless rotors are an attractive and recently studied solution in low-speed applications, due to their potentially high power/weight ratio, high aspect ratio, and high efficiency. Nevertheless, these machines are prone to be affected by manufacturing tolerance during its fabrication process and consequently, the magnets may move freely inside the rotor structure. This work presents a statistical analysis of manufacturing tolerances of an AFPM machine with an ironless rotor, considering several magnet fault types. A computationally efficient superposition method is developed and implemented to obtain both the cogging torque and rated torque considering several tolerance combinations with acceptable accuracy. The results obtained from a statistical analysis of 10,000 designs of a two-stator one rotor tooth coil winding AFPM (TCW-AFPM) machine allowed us to identify the parameters with the most impact on relevant performance indicators and disclosed a substantial increase in cogging and ripple torque when unavoidable combined tolerances are present
Seguimiento del proceso de forestación del 2005 al 2010 en el Campus UAZ Siglo XXI
La Universidad Autónoma de Zacatecas es la Institución educativa más importante del Estado de Zacatecas, fundada en 1778 como Real Colegio de San Luis Gonzaga, hasta que durante el período gubernamental del ingeniero José Isabel Rodríguez Elías, se permitió que el Instituto de Ciencias Autónomo de Zacatecas, mediante decreto del 6 de septiembre de 1968, el ejecutivo del Estado lo transformara en la Universidad Autónoma de Zacatecas. En los primeros años como universidad, la institución, al lado de un proceso vertiginoso de desarrollo, muestra en su interior una dinámica de discusión y análisis de sus estructuras, organización, funcionamiento, contenidos, metodología y técnicas de la enseñanza, vinculación con los sectores desprotegidos de la sociedad, entre otros. En 1999-2000 se realizó el Foro General de Reforma, con una amplia participación de la Comunidad Universitaria, logrando consensar resolutivos que fueron aprobados por el H. Consejo Universitario, que derivaron en los lineamientosgenerales para el actual modelo académico UAZ Siglo XXI.Universidad Nacional de La Plat
Seguimiento del proceso de forestación del 2005 al 2010 en el Campus UAZ Siglo XXI
La Universidad Autónoma de Zacatecas es la Institución educativa más importante del Estado de Zacatecas, fundada en 1778 como Real Colegio de San Luis Gonzaga, hasta que durante el período gubernamental del ingeniero José Isabel Rodríguez Elías, se permitió que el Instituto de Ciencias Autónomo de Zacatecas, mediante decreto del 6 de septiembre de 1968, el ejecutivo del Estado lo transformara en la Universidad Autónoma de Zacatecas. En los primeros años como universidad, la institución, al lado de un proceso vertiginoso de desarrollo, muestra en su interior una dinámica de discusión y análisis de sus estructuras, organización, funcionamiento, contenidos, metodología y técnicas de la enseñanza, vinculación con los sectores desprotegidos de la sociedad, entre otros. En 1999-2000 se realizó el Foro General de Reforma, con una amplia participación de la Comunidad Universitaria, logrando consensar resolutivos que fueron aprobados por el H. Consejo Universitario, que derivaron en los lineamientosgenerales para el actual modelo académico UAZ Siglo XXI.Universidad Nacional de La Plat
Application of microsatellite markers to the management of farmed stocks of turbot Scophthalmus maximus (L., 1758)
In the present study, eight microsatellite loci were used to estimate genetic relatedness and pedigree determination in turbot Scophthalmus maximus (L., 1758). Through genotypic analysis of broodstocks and their progenies, from two different turbot hatcheries, the capacity of these loci to correctly classify individuals as related or non-related was examined. Relatedness coefficients among related and non-related individuals presented means close to those theoretically expected, and the percentages of related individuals included in all relatedness coefficients found to be below the R = 0 value ranged from 0% (hatchery A) to 29 % (hatchery B). The identification of both parents for each individual was possible in more than 80 % of the cases from hatchery A, but only 41% of those from hatchery B.Se utilizaron ocho loci microsatélites en la estimación de relaciones genéticas y determinación de pedigríes en rodaballo Scophthalmus maximus (L., 1758). Mediante el análisis de los genotipos de reproductores y descendientes de dos piscifactorías se investigó la capacidad de los loci para clasificar correctamente a los individuos como emparentados o no. Las distribuciones de los coeficientes de relación genética (R) entre individuos emparentados y no relacionados exhiben medias cercanas a las esperadas teóricamente y el porcentaje de individuos emparentados que forman el total de coeficientes de relación genética que se encuentran por debajo del valor R = 0 oscilan entre el 0 % (estación A) y el 29 % (estación B). Así mismo, la identificación correcta de ambos parentales para cada descendiente fue posible en más del 80 % de los casos en la estación A y en sólo el 41 % en la estación B.Instituto Español de Oceanografí
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