The contribution of recombination to heterozygosity differs among plant evolutionary lineages and life-forms

<p>Abstract</p> <p>Background</p> <p>Despite its role as a generator of haplotypic variation, little is known about how the rates of recombination evolve across taxa. Recombination is a very labile force, susceptible to evolutionary and life trait related processes, which have also been correlated with general levels of genetic diversity. For example, in plants, it has been shown that long-lived outcrossing taxa, such as trees, have higher heterozygosity (<it>H</it>_e) at SSRs and allozymes than selfing or annual species. However, some of these tree taxa have surprisingly low levels of nucleotide diversity at the DNA sequence level, which points to recombination as a potential generator of genetic diversity in these organisms. In this study, we examine how genome-wide and within-gene rates of recombination evolve across plant taxa, determine whether such rates are influenced by the life-form adopted by species, and evaluate if higher genome-wide rates of recombination translate into higher <it>H</it>_evalues, especially in trees.</p> <p>Results</p> <p>Estimates of genome-wide (cM/Mb) recombination rates from 81 higher plants showed a significant phylogenetic signal. The use of different comparative phylogenetic models demonstrated that there is a positive correlation between recombination rate and <it>H</it>_e(0.83 ± 0.29), and that trees have higher rates of genome-wide recombination than short-lived herbs and shrubs. A significant taxonomic component was further made evident by our models, as conifers exhibited lower recombination rates than angiosperms. This trend was also found at the within-gene level.</p> <p>Conclusions</p> <p>Altogether, our results illustrate how both common ancestry and life-history traits have to be taken into account for understanding the evolution of genetic diversity and genomic rates of recombination across plant species, and highlight the relevance of species life forms to explain general levels of diversity and recombination.</p

Chondrocyte Turnover in Lung Cartilage

Cartilage is a highly differentiated connective tissue that forms mechanical support to soft tissues and is important for bone development from fetal period to puberty. It is conformed by chondrocytes and extracellular matrix. It is generally believed that adult cartilage has no capacity to renewal. A delicate balance between cell proliferation and cell death ensures the maintenance of normal tissue morphology and function. Stem cells play essential roles in this process. Mesenchymal stem cells (MSCs) can give rise to multiple lineages including bone, adipose and cartilage. Nestin protein was initially identified as a marker for neural stem cells, but its expression has also been detected in many types of cells, including MSCs. In vivo, chondrocyte turnover has been almost exclusively studied in articular cartilage. In this chapter we will review the findings about the chondrocyte turnover in lung cartilage. We have presented evidence that there exist nestin-positive MSCs in healthy adulthood that participates in the turnover of lung cartilage and in lung airway epithelium renewal. These findings may improve our knowledge about the biology of the cartilage and of the stem cells, and could provide new cell candidates for cartilage tissue engineering and for therapy for devastating pulmonary diseases

Differentiation of an adult neuron cell line increases susceptibility to rabies infection.

A wide variety of in vitro models have been used for studying rabies infection, however, currently, no central nervous system (CNS) adult neuron cultures are available. The current study determined the susceptibility to rabies infection in an adult CNS neuron cell line (CAD-R1). Cultures of CAD-R1 cells were held for 5 days in medium containing serum (undifferentiated CAD-R1 cells) or in serum-free medium (differentiated CAD-R1 cells). They were then infected with highly neurotropic rabies virus (RV) strain (CVS), obtained from fibroblastic cells (CVS-BHK) or from adult mouse brain (CVS-MB). Undifferentiated and differentiated cells were infected with the two RV strains, but the percentage of infected cells in differentiated cultures was significantly greater (83% and 79%, respectively) than in undifferentiated cells (51% and 60%) (Student's t testUna gran variedad de modelos in vitro se usan para estudiar la infección por virus de rabia, pero hasta el momento no se dispone de una línea neuronal adulta del sistema nervioso central (SNC) para dichos estudios. Por esta razón, nuestro objetivo fue determinar la susceptibilidad de una línea neuronal adulta del SNC (CAD-R1) a la infección por virus de rabia. Para ello, los cultivos se mantuvieron por 5 días en medio con suero (células CAD-R1 indiferenciadas) o sin suero (células CAD-R1 diferenciadas). Luego, se infectaron con una cepa de virus de rabia altamente neurotrópica (CVS) mantenida en células de tipo fibroblástico (CVS-BHK) o en cerebro de ratón (CVS-CR). Los dos tipos de células (indiferenciadas y diferenciadas) se infectaron con ambas cepas de virus de rabia; la proporción de células infectadas en los cultivos diferenciados fue mucho mayor (porcentajes de infección de 83,2% y 78,7% para CVS-BHK y CVS-CR, respectivamente) que en las células indiferenciadas (51,4% y 60,4%) (prueba t de Studen

Ecosystem services of tropical dry forests : insights from longterm ecological and social research on the Pacific coast of Mexico

In the search for an integrated understanding of the relationships among productive activities, human well-being, and ecosystem functioning, we evaluated the services delivered by a tropical dry forest (TDF) ecosystem in the Chamela Region, on the Pacific Coast of Mexico. We synthesized information gathered for the past two decades as part of a long-term ecosystem research study and included social data collected in the past four years using the Millennium Ecosystem Assessment (MA) conceptual framework as a guide. Here we identify the four nested spatial scales at which information has been obtained and emphasize one of them through a basin conceptual model. We then articulate the biophysical and socio-economic constraints and drivers determining the delivery of ecosystem services in the Region. We describe the nine most important services, the stakeholders who benefit from those services, and their degree of awareness of such services. We characterize spatial and temporal patterns of the services&rsquo; delivery as well as trade-offs among services and stakeholders. Finally, we contrast three alternative future scenarios on the delivery of ecosystem services and human well-being. Biophysical and socioeconomic features of the study site strongly influence human&minus;ecosystem interactions, the ecosystem services delivered, the possible future trajectories of the ecosystem, and the effect on human well-being. We discuss future research approaches that will set the basis for an integrated understanding of human&minus;ecosystem interactions and for constructing sustainable management strategies for the TDF.<br /

Functional upgrading in China’s export processing sector

Functional upgrading occurs when a firm acquires more sophisticated functions within an existing value chain. In this paper, we analyze if there is evidence of this type of upgrading in China’s export processing regime by investigating dynamics in the relative prevalence of Import & Assembly (IA) versus Pure Assembly (PA) processing trade over the period 2000-2013. Firms in both regimes provide similar manufacturing services to foreign companies, but IA firms also conduct the sophisticated tasks of quality control, searching, financing and storing imported materials. Consistent with a trend of functional upgrading, we show that the share of IA trade in total processing trade has increased rapidly during the period 2000-2006, both overall and within product categories. Furthermore, we find that this trend has gone hand in hand with improvements in a sector’s labor productivity and unit values. Against expectations, we find that this process has slowed down notably during the period 2006-2013.status: publishe

Vulnerabilidad y adaptación de la zona costera colombiana al ascenso acelerado del nivel del mar

El país posee una variada y dinámica zona costera, que alcanza 3340 Km de extensión y que comprende dos litorales, el Caribe y el pacífico, y un territorio insular en el que se incluye el Archipiélago de San Andrés y Providencia. En su zona de costa y plataforma continental se encuentran importantes ecosistemas como manglares, praderas de fanerógamas y arrecifes coralinos, distribuidas por sus costas bajas y estuarinas, bahías, ensenadas y las costas arenosas y acantiladas. Tanto su línea de costa alta, como las planicies litorales bajas y ecosistemas costeros serán afectados por el actual cambio climático, y en especial, por el ascenso acelerado del nivel del mar. Los efectos del potencial ascenso del nivel marino fueron evaluados mediante indicadores geomorfológicos y morfo- dinámicos, con base en la caracterización física del litoral, la evaluación de su susceptibilidad y la proyección de los posibles cambios biofísicos que causará el incremento en un metro del nivel del mar en los próximos 100 años. De acuerdo con esta evaluación, en las costas colombianas es posible la inundación permanente de 4900 Km2 de costas bajas, el encharcamiento fuerte a total anegamiento de 5100 Km2 de áreas costeras moderadamente susceptibles, así como el encharcamiento de zonas aledañas y la profundización de los cuerpos de agua localizados en la zona litoral y la plataforma. Igualmente causará el incremento de la erosión en zonas especialmente sensibles, donde la actividad antrópica a reducido la capacidad de amortiguación de los sistemas litorales. Sistemas naturales como las playas y marismas serán los mas afectados por la erosión y la inundación litoral de acuerdo con esta evaluación. Se pudo establecer que los potenciales cambios biofísicos que afectarán el litoral colombiano por el cambio del nivel del mar harán que parte importante de la población, las actividades económicas y la infraestructura vital del país sean amenazadas por la inundación marina. La población que se encuentra en áreas bajo amenaza por inundación alcanza aproximadamente 1.4 millones de habitantes del litoral, población que esta dominantemente asentada en el sector urbano (85%). Para el litoral Caribe, sólo el 9% de las viviendas urbanas presentan alta vulnerabilidad a la inundación, porcentaje que llega al 46% en el sector rural. En el litoral Pacífico, el 48% de las viviendas del sector urbano y 87% del sector rural son altamente vulnerables, sin embargo, debido a las tradiciones culturales gran porcentaje de ellas están construidas sobre palafitos, costumbre que facilitará la adaptación. En cuanto a la vulnerabilidad social de los hogares en el litoral Caribe el 74% son moderadamente vulnerables, el 17% altamente vulnerables y el 9% son poco vulnerables. En el litoral Pacífico los hogares con alta vulnerabilidad social alcanzan el 13%, son moderadamente vulnerables el 62% y el restante 25% tiene baja vulnerabilidad. Respecto a las actividades económicas, se analizaron los principales sectores económicos asentados en el litoral Caribe, donde se concentra preferencialmente la infraestructura industrial y portuaria. El análisis de los elementos socioeconómicos permitió concluir que en el sector agropecuario, de las 1.533.290 Has de cultivos y pastos reportadas el 21% están expuestas a los diferentes grados de amenaza por inundación, de las cuales el 49% presentan alta vulnerabilidad y que está representada en cultivos de banano y palma africana principalmente. En el sector industrial, se encontró que el 75.3% (475 Has) del área ocupada por los establecimientos manufactureros en Barranquilla y el 99.7% (877 Has) en Cartagena son de alta vulnerabilidad. Para la infraestructura vial se considera que el 44.8% de la infraestructura vial terrestre tiene alta vulnerabilidad, el 5.2% vulnerabilidad moderada y el 22.7% es poco vulnerable. En las zonas insulares se analizó la vulnerabilidad de la isla de San Andrés, ubicada en el mar Caribe y que hace parte de un extenso archipiélago coralino de 52.2. km2. La isla de San Andrés cubre un área de 27 Km2, de los cuales el 17% sería inundado por un ascenso proyectado de 1 metro del nivel del mar, espacio que se localiza en las zonas norte y este de la isla. Las zonas mas afectadas por la inundación representan la mayor parte de la riqueza natural de la isla, y es también el sector donde se asienta la infraestructura turística y comercial. La alta vulnerabilidad de estas zonas es debida a la presencia de rellenos habilitados en la década de los años 50. Igualmente, la infraestructura de servicios públicos será afectada, en especial el alcantarillado, el abastecimiento de agua potable y la infraestructura vial, además del incremento de los actuales procesos de erosión. Se considera la implementación de medidas de adaptación tendientes a recuperar y fortalecer los mecanismos de resiliencia del litoral que faciliten la adaptación natural de las zonas costeras al ascenso del nivel del mar. Opciones adicionales como la preservación de humedales costeros, regulación de los usos y actividades en las zonas amenazadas por la inundación y la protección de zonas de interés socioeconómico vital complementan la estrategia de adaptación, consolidada en el marco del manejo integrado de zonas costeras que ha establecido el país para sus litorales

Polygenic adaptation and negative selection across traits, years and environments in a long-lived plant species (Pinus pinaster Ait., Pinaceae)

17 Pág.A decade of genetic association studies in multiple organisms suggests that most complex traits are polygenic; that is, they have a genetic architecture determined by numerous loci, each with small effect-size. Thus, determining the degree of polygenicity and its variation across traits, environments and time is crucial to understand the genetic basis of phenotypic variation. We applied multilocus approaches to estimate the degree of polygenicity of fitness-related traits in a long-lived plant (Pinus pinaster Ait., maritime pine) and to analyse this variation across environments and years. We evaluated five categories of fitness-related traits (survival, height, phenology, functional, and biotic-stress response) in a clonal common-garden network planted in contrasted environments (over 20,500 trees). Most of the analysed traits showed evidence of local adaptation based on Qst -Fst comparisons. We further observed a remarkably stable degree of polygenicity, averaging 6% (range of 0%-27%), across traits, environments and years. We detected evidence of negative selection, which could explain, at least partially, the high degree of polygenicity. Because polygenic adaptation can occur rapidly, our results suggest that current predictions on the capacity of natural forest tree populations to adapt to new environments should be revised, especially in the current context of climate change.This study was funded by the Spanish Ministry of Economy and Competitiveness through projects RTA2010-00120-C02- 02 (CLONAPIN), CGL2011-30182- C02- 01 (AdapCon) and AGL2012-40151- C03- 02 (FENOPIN). The study was also supported by the “Initiative d’Excellence (IdEx) de l’Université de Bordeaux - Chaires d'installation 2015” (EcoGenPin) and the European Union's Horizon 2020 research and innovation programme under grant agreement No 773383 (B4EST)Peer reviewe

Parasitic copepods (Crustacea, Hexanauplia) on fishes from the lagoon flats of Palmyra Atoll, Central Pacific

We surveyed copepods parasitic on the fishes at Palmyra, a remote atoll in the Central Indo-Pacific faunal region. In total, we collected 849 individual fish, representing 44 species, from the intertidal lagoon flats at Palmyra and recovered 17 parasitic copepod species. The parasitic copepods were: Orbitacolax williamsi on Mulloidichthys flavolineatus; Anuretes serratus on Acanthurus xanthopterus; Caligus confusus on Carangoides ferdau, Carangoides orthogrammus, Caranx ignobilis, Caranx melampygus, and Caranx papuensis; Caligus kapuhili on Chaetodon auriga and Chaetodon lunula; Caligus laticaudus on Rhinecanthus aculeatus, Pseudobalistes flavimarginatus, M. flavolineatus, Upeneus taeniopterus, Chrysiptera glauca, and Epinephalus merra; Caligus mutabilis on Lutjanus fulvus and Lutjanus monostigma; Caligus randalli on C. ignobilis; Caligus sp. on L. fulvus; Caritus serratus on Chanos chanos; Lepeophtheirus lewisi on A. xanthopterus; Lepeophtheirus uluus on C. ignobilis; Dissonus similis on Arothron hispidus; Nemesis sp. on Carcharhinus melanopterus; Hatschekia longiabdominalis on A. hispidus; Hatschekia bicaudata on Chaetodon auriga and Chaetodon lunula; Kroyeria longicauda on C. melanopterus and Lernanthropus sp. on Kyphosus cinerascens. All copepod species reported here have been previously reported from the Indo-Pacific but represent new geographical records for Palmyra, demonstrating large-scale parasite dispersion strategies