669 research outputs found
Assessment of Land Cover Changes in the Hinterland of Barranquilla (Colombia) Using Landsat Imagery and Logistic Regression
Barranquilla is known as a dynamically growing city in the Colombian Caribbean. Urbanisation induces land use and land cover (LULC) changes in the city and its hinterland affecting the region’s climate and biodiversity. This paper aims to identify the trends of land use and land cover changes in the hinterland of Barranquilla corresponding to 13 municipalities in the north of the Department Atlántico. Landsat TM/ETM/OLI imagery from 1985 to 2017 was used to map and analyse the spatio-temporal development of land use and land cover changes. During the investigation period, the settlement areas grew by approximately 50% (from 103.3 to 153.6 km2), while areas with woody vegetation cover experienced dynamic changes and increased in size since 2001. Peri-urban and rural areas were characterized by highly dynamic changes, particularly regarding clearing and recovery of vegetated areas. Regression analyses were performed to identify the impact factors of detected vegetation cover changes. Computed logistic regression models included 20 independent variables, such as relief, climate, soil, proximity characteristics and socio-economic data. The results of this study may act as a basis to enable researchers and decision-makers to focus on the most important signals of systematic landscape transformations and on the conservation of ecosystems and the services they provide
The Utility of Genomic Variant Databases in Genetic Counseling
Organizations such as the American College of Medical Genetics (ACMG) and the National Society of Genetic Counselors (NSGC) are in agreement that public genomic data sharing will benefit patient care. Despite these recommendations, not all clinical laboratories share their variant data onto public databases. As the amount of genetic material being analyzed for patient care continues to increase, more variants of unknown significance (VUS) are reported as well. Genetic counselors need to properly interpret VUS results in order to aid patients in making educated health decisions. For this paper, genetic counselors were asked about genomic data sharing and how they handle VUS results for patients. While almost all genetic counselors agree that there is a need for genomic data sharing, only some took laboratories’ data sharing practices into account when deciding where to order testing. Genetic counselors do not have a standard way of processing VUS results; there is little consistency to how often genetic counselors look up variants in public databases or which databases they use
Melanocortin-4 receptor gene: case-control study and transmission disequilibrium test confirm that functionally relevant mutations are compatible with a major gene effect for extreme obesity
We initially performed a mutation screen of the coding region of the MC4R in 808 extremely obese children and adolescents and 327 underweight or normal-weight controls allowing for a case-control study. A total of 16 different missense, nonsense, and frameshift mutations were found in the obese study group; five of these have not been observed previously. In vitro assays revealed that nine [the haplotype (Y35X; D37V) was counted as one mutation] of the 16 mutations led to impaired cAMP responses, compared with wild-type receptor constructs. In contrast, only one novel missense mutation was detected in the controls, which did not alter receptor function. The association test based on functionally relevant mutations was positive (P = 0.006, Fisher's exact test, one-sided). We proceeded by screening a total of 1040 parents of 520 of the aforementioned obese young index patients to perform transmission disequilibrium tests. The 11 parental carriers of functionally relevant mutations transmitted the mutation in 81.8% (P = 0.033; exact one-sided McNemar test). These results support the hypothesis that these MC4R mutations represent major gene effects for obesity
Acquisition of Relative Interstrand Crosslinker Resistance and PARP Inhibitor Sensitivity in Fanconi Anemia Head and Neck Cancers
PURPOSE: Fanconi anemia is an inherited disorder associated with a constitutional defect in the Fanconi anemia DNA repair machinery that is essential for resolution of DNA interstrand crosslinks. Individuals with Fanconi anemia are predisposed to formation of head and neck squamous cell carcinomas (HNSCC) at a young age. Prognosis is poor, partly due to patient intolerance of chemotherapy and radiation requiring dose reduction, which may lead to early recurrence of disease.
EXPERIMENTAL DESIGN: Using HNSCC cell lines derived from the tumors of patients with Fanconi anemia, and murine HNSCC cell lines derived from the tumors of wild-type and Fancc(-/-) mice, we sought to define Fanconi anemia-dependent chemosensitivity and DNA repair characteristics. We utilized DNA repair reporter assays to explore the preference of Fanconi anemia HNSCC cells for non-homologous end joining (NHEJ).
RESULTS: Surprisingly, interstrand crosslinker (ICL) sensitivity was not necessarily Fanconi anemia-dependent in human or murine cell systems. Our results suggest that the increased Ku-dependent NHEJ that is expected in Fanconi anemia cells did not mediate relative ICL resistance. ICL exposure resulted in increased DNA damage sensing and repair by PARP in Fanconi anemia-deficient cells. Moreover, human and murine Fanconi anemia HNSCC cells were sensitive to PARP inhibition, and sensitivity of human cells was attenuated by Fanconi anemia gene complementation.
CONCLUSIONS: The observed reliance upon PARP-mediated mechanisms reveals a means by which Fanconi anemia HNSCCs can acquire relative resistance to the ICL-based chemotherapy that is a foundation of HNSCC treatment, as well as a potential target for overcoming chemoresistance in the chemosensitive individual
Comportamento do consumidor de luxo falsificado: motivações na compra de bolsas de luxo falsificadas
Este trabalho consiste em uma pesquisa sobre o consumo de bolsas de luxo falsificadas entre mulheres da classe A da cidade do Rio de Janeiro. A pesquisa tem como objetivo identificar quais os motivos que levam o consumidor a comprar produtos de luxo falsificados e mais especificamente bolsas de luxo falsificadas. Através desse estudo, será possível compreender como aspectos como qualidade e marca influenciam o consumidor em sua tomada de decisão. Esse trabalho tem como finalidade contribuir para a formulação de políticas e campanhas que visam o combate a pirataria. A metodologia utilizada foi a realização de um levantamento através de questionários autoadministrados com o público-alvo da pesquisa e algumas entrevistas informais feitas com ambulantes de rua. A consolidação dos dados foi feita via Excel e o resultado mostra que as respondentes acreditam que a redução do preço do produto original poderia gerar uma mudança de atitude dos consumidores, embora algumas delas acreditem que o fato destas bolsas terem um preço elevado é o que gera o diferencial delas
Nested singletons in molecular trees: Utility of adding morphological and geographical data from digitized herbarium specimens to test taxon concepts at species level in the case of Casearia (Salicaceae)
Using the genus Casearia, we assessed the status of nested singletons: individual specimens corresponding to accepted species but in molecular trees appearing nested within clades of closely related species. Normally, such cases would be left undecided, while on the other hand, timely taxonomic decisions are required. We argue that morphological, chorological, and ecological data can be informative to illuminate patterns of speciation. Their use can provide a first step in testing taxon concepts at species level. We focused on five cases of nested singletons in trees of the genus Casearia. We employed PCA and cluster analysis to assess phenotypic differentiation. Using geocoordinates, we calculated niche space differentiation based on 19 bioclim variables, by means of PCA and niche equivalency and similarity tests and generated dot maps. We found that the singletons were morphologically distinctive in two of the five cases (Casearia selloana and C. manausensis), relatively distinctive in two other cases (C. zizyphoides and C. mariquitensis), and partially overlapping in the last case (C. grandiflora). For two cases (C. mariquitensis and C. selloana), ecological niche space was broadly overlapping, in two cases it was found broadly nested (C. grandiflora and C. zizyphoides), and in one case narrowly nested (C. manausensis), but in no case niche differentiation was observed. Niche overlap, similarity and equivalency showed corresponding patterns. Given these data, one would interpret C. selloana and C. manausensis as presumably well-distinguished taxa, their narrow distribution ranges suggesting recently emerging lineages. The other three cases are not clearcut. Morphological data would suggest particularly C. grandiflora conspecific with C. arborea, but differences in the distribution are intriguing. Our approach would reject the notion of potential synonymy based on nested phylogenetic placement for at least two of the five cases. The other case also shows no complete lack of differentiation which would support synonymy
Character evolution and biogeography of Casearia (Salicaceae): Evidence for the South American origin of a pantropical genus and for multiple migrations to the Caribbean islands
Casearia (Salicaceae) is a pantropical genus of circa 200 species, around half of which dwell in the Neotropics. Despite the availability of phylogenetic studies that suggest that Casearia sensu Sleumer is not monophyletic, a strong phylogenetic framework was still lacking for this genus. We tested the monophyly of Casearia and examined the relationships of its species to other taxa of the tribe Samydeae, including Laetia, Samyda and Zuelania, which recently have been sunk into Casearia, as well as Euceraea, Lunania, Neoptychocarpus, Ryania and Tetrathylacium. We further put a focus on the Neotropical taxa since Casearia and allies are speciose both on the Caribbean islands and adjacent mainlands, thus providing an interesting group to address the origin of the Caribbean and Cuban flora. Our phylogenetic analyses based on four combined rapidly evolving plastid regions (petD, rpl16, rps4-trnT-L-F, trnK-matK-psbA) as well as nuclear ITS revealed Casearia as monophyletic with high support, including not only the former members of Laetia, Samyda and Zuelania but also Euceraea and Neoptychocarpus. Casearia is constituted by several major clades, mostly being entirely Neotropical, one of which exclusively comprises species endemic to the Caribbean islands. Another clade, which includes all Palaeotropical species, is nested among Neotropical lineages. Our divergence date estimates using the plastid dataset and fossil calibration points in Salicaceae indicate that the Casearia crown group started to diversify during the late Eocene, approximately 39 Ma. The stem of the Old World clade diverged from Neotropical ancestors around 27 Ma, in the Oligocene. We used BayesTraits to reconstruct the evolution of seven characters commonly used to define Casearia and allied genera. We found morphological characters, such as branched inflorescences (fasciculate, glomerulous, cymose) or uniseriate stamen series, that work well to circumscribe the genus, whereas dioecy, which was used to diagnose Neoptychocarpus, or higher stamen numbers (>12), found in Laetia and Zuelania, are homoplastic in Salicaceae, the latter character derived within Casearia from ancestors with 7–12 stamens. Pellucid dots appear to have evolved earlier than the divergence of the Casearia clade in Samydeae, and were lost in Ryania and Tetrathylacium, and thus are no synapomorphy for Casearia. In order to establish a monophyletic genus concept for Casearia, we propose to also merge Euceraea and Neoptychocarpus. Our reconstruction of ancestral areas using BioGeoBears indicate that South America is the ancestral area of Casearia. From there, multiple migrations occurred to Mesoamerica and the Caribbean islands. The Caribbean that comprises nearly all Caribbean endemics started to diversify around 9.5 Ma. Our trees depict C. corymbosa, which exhibits significant infraspecific phylogenetic structure for the sampled Mexican and Colombian individuals, as the sister to the Caribbean clade. The other clade, with Cuban endemics (C. ternstroemioides) but also Mesoamerican and South American taxa, is not sufficiently resolved internally, to allow biogeographic conclusions. The Old World clade of Casearia provides another example for a late Laurasian migration starting in the Neotropics
Seeing the wood despite the trees: Exploring human disturbance impact on plant diversity, community structure, and standing biomass in fragmented high Andean forests
High Andean forests harbor a remarkably high biodiversity and play a key role in providing vital ecosystem services for neighboring cities and settlements. However, they are among the most fragmented and threatened ecosystems in the neotropics. To preserve their unique biodiversity, a deeper understanding of the effects of anthropogenic perturbations on them is urgently needed. Here, we characterized the plant communities of high Andean forest remnants in the hinterland of Bogota in 32 0.04 ha plots. We assessed the woody vegetation and sampled the understory and epiphytic cover. We gathered data on compositional and structural parameters and compiled a broad array of variables related to anthropogenic disturbance, ranging from local to landscape-wide metrics. We also assessed phylogenetic diversity and functional diversity. We employed nonmetric multidimensional scaling (NMDS) to select meaningful variables in a first step of the analysis. Then, we performed partial redundancy analysis (pRDA) and generalized linear models (GLMs) in order to test how selected environmental and anthropogenic variables are affecting the composition, diversity, and aboveground biomass of these forests. Identified woody vegetation and understory layer communities were characterized by differences in elevation, temperature, and relative humidity, but were also related to different levels of human influence. We found that the increase of human-related disturbance resulted in less phylogenetic diversity and in the phylogenetic clustering of the woody vegetation and in lower aboveground biomass (AGB) values. As to the understory, disturbance was associated with a higher diversity, jointly with a higher phylogenetic dispersion. The most relevant disturbance predictors identified here were as follows: edge effect, proximity of cattle, minimum fragment age, and median patch size. Interestingly, AGB was efficiently predicted by the proportion of late successional species. We therefore recommend the use of AGB and abundance of late successional species as indicators of human disturbance on high Andean forests
In situ propagation of rhatany - Krameria lappacea (Krameriaceae): factors limiting natural regeneration and effects of reseeding measures
Krameria lappacea (ratania) ha sido utilizada y reconocida como planta medicinal y tintura vegetal desde épocas precolombinas. En los últimos 15 años se han estudiado la biología, propagación y abundancia de ratania en Perú y desarrollado métodos que garanticen una recolección silvestre sostenible. El objetivo de este trabajo es investigar qué factores limitan la propagación natural y evaluar si una resiembra de semillas durante la recolección puede facilitar el establecimiento de plantas nuevas in situ. Al investigarse la germinación de las semillas y la propagación in situ pudo comprobarse mediante experimentos de invernadero que el entierro de las semillas es un factor limitante para la germinación de K. lappacea y que la tasa de germinación puede incrementarse significativamente (3 – 4x) al enterrar las semillas. Tanto la resiembra de las semillas en los hoyos realizados tras la cosecha, así como la resiembra más esparcida en parcelas seleccionadas, puede contribuir al reforzamiento de la regeneración natural. Las raíces secundarias que quedan en el suelo después de la cosecha forman un nuevo meristemo y dan lugar al desarrollo de nuevas plantas. El pre-tratamiento de las semillas (escarificación) no produce ningún efecto claro en el éxito de la germinación, sin embargo, esta práctica facilita la manipulación durante la resiembra, asegurando que únicamente semillas viables y completamente desarrolladas sean utilizadas posteriormente.Krameria lappacea (rhatany) is a well established medicinal and dye plant that is used since pre-Colombian times. In the last 15 years the biology, distribution and abundance of rhatany in Peru was investigated and methods for a sustainable wildcrafting were developed. The objective of this work was to investigate which factors limit the natural propagation and to explore whether the reseeding measures can contribute to the establishment of new plants in situ. Investigating the germination and in situ propagation, greenhouse trials showed that the seed burial is an important, limiting factor for the germination of K. lappacea und the germination rate can be increased (3—4x) by burying the seeds. Both the burial of the seeds during collection and re-sowing measures on selected lots can contribute to the rejuvenation of the population. Secondary roots, which are left in the ground during harvest, are showed to form new shoot meristems and develop into new plants. Pre-treatment (scarification) of the fruits does not clearly influence the germination success, but it facilitates the handling of the seeds during re-sowing and ensures the use of only fully developed, viable seeds
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