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1.
Case Rep Dent ; 2024: 8966953, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38250626

RESUMO

Extraosseous variants of odontogenic cysts are an infrequent clinical finding, although they have a relatively indolent biological behavior compared to their intraosseous counterparts; due to their nature and clinical appearance, these lesions can be confused with multiple entities that affect soft tissues, so their diagnosis can only be achieved through surgical removal and subsequent histopathological analysis. The extraosseous/peripheral variant of calcifying odontogenic cyst (E/PCOC) has a heterogeneous clinical presentation mainly in terms of size and involvement or not of adjacent anatomical structures such as bone and teeth; in addition, there are few cases reported to date; thus, there are still clinical features to be elucidated. This report presents a child affected by E/PCOC in an unusual location, as well as its therapeutic management, which at first time was suspected of endodontic nature, due to a history of dental trauma.

2.
Ecol Evol ; 13(12): e10801, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-38089899

RESUMO

Reproductive isolation is conferred by several barriers that occur at different stages of reproduction. Comprehensive reviews on the topic have identified that barriers occurring prior to zygote formation are often stronger than those that occur afterward. However, the overrepresentation of temperate perennial herbs in the current literature precludes any generalization of this pattern to plants that present other life forms and patterns of distribution. Here, we assessed reproductive isolation barriers and their absolute contribution to reproductive isolation and asymmetry in Cnidoscolus aconitifolius and C. souzae, two closely related tropical shrub species that co-occur on the Yucatan peninsula. The reproductive barriers assessed were phenological mismatch, pollinator differentiation, pollen-pistil incompatibility (three pre-zygotic barriers), fruit set failure, and seed unviability (post-zygotic barriers). Reproductive isolation between the study species was found to be complete in the direction C. aconitifolius to C. souzae, but only partial in the opposite direction. One post-zygotic barrier was the strongest example. Most barriers, particularly the pre-zygotic examples, were asymmetrical and predicted the direction of heterospecific pollen flow and hybrid formation from C. souzae to C. aconitifolius. Both parental species, as well as the hybrids, were diploid and had a chromosome number 2n = 36. More studies with tropical woody perennials are required to fully determine whether this group of plants consistently shows stronger post-zygotic barriers.

3.
Sensors (Basel) ; 23(22)2023 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-38005562

RESUMO

In radar entomology, one primary challenge is detecting small species (smaller than 5 cm) since these tiny insects reflect radiation that can be poorly observable and, therefore, difficult to interpret. After a literature search on radar entomology, this research found few works where it has been possible to sense insects with dimensions smaller than 5 cm using radars. This paper describes different methodologies to detect Mediterranean fruit flies with 5-6 mm sizes using a pulsed W-band radar and presents the experimental results that validate the procedures. The article's main contribution is the successful detection of Mediterranean fruit flies employing the shadow effect on the backscattered radar signal, achieving an 11% difference in received power when flies are present. So far, according to the information available and the literature search, this work is the first to detect small insects less than 1 cm long using a pulsed radar in W-Band. The results show that the proposed shadow effect is a viable alternative to the current sensors used in smart traps, as it allows not only detection but also counting the number of insects in the trap.


Assuntos
Insetos , Radar , Animais
4.
New Phytol ; 239(5): 1723-1739, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-37421201

RESUMO

Here, we discover a player in root development. Recovered from a forward-genetic screen in Brachypodium distachyon, the buzz mutant initiates root hairs but they fail to elongate. In addition, buzz roots grow twice as fast as wild-type roots. Also, lateral roots show increased sensitivity to nitrate, whereas primary roots are less sensitive to nitrate. Using whole-genome resequencing, we identified the causal single nucleotide polymorphism as occurring in a conserved but previously uncharacterized cyclin-dependent kinase (CDK)-like gene. The buzz mutant phenotypes are rescued by the wild-type B. distachyon BUZZ coding sequence and by an apparent homolog in Arabidopsis thaliana. Moreover, T-DNA mutants in A. thaliana BUZZ have shorter root hairs. BUZZ mRNA localizes to epidermal cells and develops root hairs and, in the latter, partially colocalizes with the NRT1.1A nitrate transporter. Based on qPCR and RNA-Seq, buzz overexpresses ROOT HAIRLESS LIKE SIX-1 and -2 and misregulates genes related to hormone signaling, RNA processing, cytoskeletal, and cell wall organization, and to the assimilation of nitrate. Overall, these data demonstrate that BUZZ is required for tip growth after root hair initiation and root architectural responses to nitrate.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Brachypodium , Proteínas de Arabidopsis/metabolismo , Nitratos/metabolismo , Genes Essenciais , Raízes de Plantas/metabolismo , Regulação da Expressão Gênica de Plantas
5.
Curr Biol ; 33(9): R359-R361, 2023 05 08.
Artigo em Inglês | MEDLINE | ID: mdl-37160093

RESUMO

Root growth inhibition under phosphorous deficiency was long hypothesized to be the result of toxic iron levels in root tips. However, a new study reveals ARSK1 and TOR1 regulate root growth within hours of phosphorous starvation prior to changes in iron accumulation.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Alvo Mecanístico do Complexo 1 de Rapamicina , Fósforo , Raízes de Plantas , Arabidopsis/crescimento & desenvolvimento , Raízes de Plantas/crescimento & desenvolvimento , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Fósforo/deficiência , Ferro/metabolismo , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Mutação
6.
BMJ Case Rep ; 15(3)2022 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-35256361

RESUMO

Venous malformations (VMs) are a type of vascular malformation formed by abnormally developed venous channels, with variations in size, pathway and thickness and are therefore a condition which can predispose to thrombosis. We present the case of a VM associated with phlebothrombosis/phlebolith, located on the lingual dorsum of a 20-year-old female patient. Clinical examination revealed a nodule of approximately 5 mm in diameter involving the anterior third of lingual dorsum, with a firm, compressible and non-pulsatile consistency. Histopathologically, the lesion revealed a VM with evidence of phlebothrombosis and phlebolith development. Although VMs manifest infrequently in this age group, they should be considered in the differential diagnosis of other lesions with similar characteristics in young people.


Assuntos
Doenças da Língua , Malformações Vasculares , Trombose Venosa , Adolescente , Adulto , Feminino , Humanos , Língua/patologia , Malformações Vasculares/complicações , Malformações Vasculares/diagnóstico , Veias/patologia , Adulto Jovem
7.
Naturwissenschaften ; 109(1): 12, 2022 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-34994866

RESUMO

Cities are home to several species of pollinators that play an important role in the reproductive success of wild and cultivated plants that grow in these ecosystems and their surroundings. Pollution is a main driver of pollinator decline. Light and noise pollution are more intense in cities than in any other ecosystem. Although nocturnal pollinators are heavily exposed to these pollutants, their effect on bat pollination is still unknown. Our goal was to assess the effect of light and noise pollution on the main pollination components (pollinator visits, pollen transfer, pollen germination, fruit, and seed set) of the tropical tree, Ceiba pentandra, in a heavily urbanized ecosystem. We measured these components in sites with contrasting intensities of artificial light and anthropogenic noise and statistically assessed the direct and indirect effect of pollutants on pollination components using structural equation modeling. We found that noise and light pollution negatively affected the visits by the bats that pollinate C. pentandra. However, these negative effects did not affect posterior pollination components. In fact, the direct effect of light pollution on reproductive success was positive and greater than the indirect effects via pollinator visits. We suggest that illuminated trees may be able to sustain a large quantity of fruits and seeds because they produce more photosynthates due to greater light radiation and delayed leaf abscission. We conclude that, despite the negative effect of light and noise on pollinator visits, these pollutants did not significantly impact the reproductive success of C. pentandra.


Assuntos
Quirópteros , Árvores , Animais , Ecossistema , Flores , Poluição Luminosa , Polinização , Reprodução
8.
Sci Rep ; 11(1): 21017, 2021 10 25.
Artigo em Inglês | MEDLINE | ID: mdl-34697356

RESUMO

The clonal propagation of crops offers several advantages to growers, such as skipping the juvenile phase, faster growth, and reduced mortality. However, it is not known if the wild ancestors of most clonal crops have a similar ability to reproduce clonally. Therefore, it is unclear whether clonality was an ancestral condition, or if it evolved during domestication in the majority of these crops. Here, I assessed some traits that are relevant to clonal propagation using stem cuttings from chaya (Cnidoscolus aconitifolius) and compared these traits to those of its wild ancestor. Chaya is highly relevant crop to food security in its domestication center (Yucatan Peninsula) and is now cultivated in several countries. Chaya is also an excellent model for assessing the effect of domestication on clonality because wild relatives and selection targets are known. Specifically, I compared resistance to desiccation, water and resource storage, as well as the production of new organs (shoots and leaves) by the stems of wild and domesticated plants. I also compared their performance in root development and clone survival. I found that, relative to their wild ancestors, the stem cuttings of domesticated chaya had 1.1 times greater storage capacity for water and starch. Additionally, the stems of domesticated plants produced 1.25 times more roots, 2.69 times more shoots and 1.94 more leaves, and their clones lived 1.87 times longer than their wild relatives. In conclusion, the results suggest that artificial selection has optimized water and starch storage by stems in chaya. Because these traits also confer greater fitness (i.e. increased fecundity and survival of clones), they can be considered adaptations to clonal propagation in the agroecosystems where this crop is cultivated.


Assuntos
Evolução Clonal , Produtos Agrícolas , Euphorbiaceae , Reprodução , Domesticação , Desenvolvimento Vegetal , Característica Quantitativa Herdável
9.
BMJ Case Rep ; 14(8)2021 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-34400421

RESUMO

The extraosseous/peripheral odontogenic fibroma (E/POF) is a benign mesenchymal odontogenic tumour found on the gingival surface with clinical characteristics identical to those of reactive lesions. A histopathological analysis is the only method for determining the difference between reactive lesions and these neoplastic lesions, whose recurrence potential varies between 38.9% and 50%, highlighting the importance of correct diagnosis. The following report describes an E/POF case with a clear cells component, as well as a long-term follow-up treatment, which we emphasise due to its potential for recurrence.


Assuntos
Fibroma , Neoplasias Gengivais , Tumores Odontogênicos , Diagnóstico Diferencial , Fibroma/diagnóstico por imagem , Fibroma/cirurgia , Seguimentos , Neoplasias Gengivais/diagnóstico por imagem , Neoplasias Gengivais/cirurgia , Humanos , Recidiva Local de Neoplasia , Tumores Odontogênicos/diagnóstico por imagem , Tumores Odontogênicos/cirurgia
10.
AoB Plants ; 12(3): plaa023, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32607138

RESUMO

Phenotypic changes in plants during domestication may disrupt plant-herbivore interactions. Because wild and cultivated plants have different habitats and some anti-herbivore defences exhibit some plasticity, their defences may be also influenced by the environment. Our goal was to assess the effects of domestication and the environment on herbivory and some anti-herbivore defences in chaya (Cnidoscolus aconitifolius) in its centre of domestication. Herbivores, herbivory, and direct and indirect anti-herbivore defences were assessed in wild and cultivated plants. The same variables were measured in the field and in a common garden to assess environmental effects. Our results show that domestication increased herbivory and herbivore abundance, but reduced direct and some indirect defences (ants). The environment also affected the herbivore guild (herbivore abundance and richness) and some direct and indirect defences (trichome number and ants). There was also an interaction effect of domestication and the environment on the number of trichomes. We conclude that domestication and the environment influence herbivory and anti-herbivore defences in an additive and interactive manner in chaya.

11.
BMC Oral Health ; 20(1): 159, 2020 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-32487188

RESUMO

BACKGROUND: Pericoronal radiolucent lesions are a common radiographic finding, but it is rare that they occur in multiple forms. Multiple calcifying hyperplastic dental follicles (MCHDF) are entities with few cases described to date; nevertheless, they appear to have a very particular phenotypic pattern. CASES PRESENTATION: Case 1: A 10-year-old male was evaluated radiographically, revealing four impacted canines, each accompanied by unilocular pericoronal radiolucency. Case 2: A 16-year-old male was planning orthodontic treatment; following his radiological evaluation all third molars were found to be accompanied with pericoronal radiolucencies. Enucleation, and third molar removal along with the pericoronal tissue were the respective treatments. Microscopically, in both cases, the specimens shown odontogenic epithelium, and type I and II calcifications in the hyperplastic follicles, all these characteristics were consistent with MCHDF. CONCLUSION: Although MCHDF are a rare entity, they must be considered in the differential diagnosis of multiple pericoronal lesions. Under the light of the current evidence, the histological findings may be relatively heterogeneous, but their integration with both the clinical data, which are apparently particular, and with the radiographic characteristics, can lead to a definitive diagnosis.


Assuntos
Saco Dentário/diagnóstico por imagem , Dente Serotino/diagnóstico por imagem , Radiografia Panorâmica/métodos , Dente Impactado/diagnóstico por imagem , Adolescente , Criança , Saco Dentário/cirurgia , Cisto Dentígero/diagnóstico por imagem , Humanos , Masculino , Doenças Mandibulares/diagnóstico por imagem , Dente Molar , Dente Serotino/cirurgia , Dente Impactado/patologia , Dente Impactado/cirurgia
12.
Plant Direct ; 4(6): e00227, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32537558

RESUMO

Glutaredoxins (GRXs) are small oxidoreductase enzymes that can reduce disulfide bonds in target proteins. The class III GRX gene family is unique to land plants, and Arabidopsis thaliana has 21 class III GRXs, which remain largely uncharacterized. About 80% of A. thaliana class III GRXs are transcriptionally regulated by nitrate, and several recent studies have suggested roles for these GRXs in nitrogen signaling. Our objective was to functionally characterize two nitrate-induced GRX genes, AtGRXS5 and AtGRXS8, defining their roles in signaling and development in the A. thaliana root. We demonstrated that AtGRXS5 and AtGRXS8 are primarily expressed in root and shoot vasculature (phloem), and that the corresponding GRX proteins display nucleo-cytosolic subcellular localization. Ectopic expression of AtGRXS8 in transgenic plants caused major alterations in root system architecture: Normal primary root development, but a near absence of lateral roots. RNA sequencing demonstrated that the roots of AtGRXS8-overexpressing plants show strongly reduced transcript abundance for many primary nitrate response genes, including the major high-affinity nitrate transporters. Correspondingly, high-affinity nitrate uptake and the transport of nitrate from roots to shoots are compromised in AtGRXS8-overexpressing plants. Finally, we demonstrated that the AtGRXS8 protein can physically interact with the TGA1 and TGA4 transcription factors, which are central regulators of early transcriptional responses to nitrate in A. thaliana roots. Overall, these results suggest that AtGRXS8 acts to quench both transcriptional and developmental aspects of primary nitrate response, potentially by interfering with the activity of the TGA1 and TGA4 transcription factors.

13.
Ecol Evol ; 9(1): 587-597, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30680139

RESUMO

Many modern crop varieties rely on animal pollination to set fruit and seeds. Intensive crop plantations usually do not provide suitable habitats for pollinators so crop yield may depend on the surrounding vegetation to maintain pollination services. However, little is known about the effect of pollinator-mediated interactions among co-flowering plants on crop yield or the underlying mechanisms. Plant reproductive success is complex, involving several pre- and post-pollination events; however, the current literature has mainly focused on pre-pollination events in natural plant communities. We assessed pollinator sharing and the contribution to pollinator diet in a community of wild and cultivated plants that co-flower with a focal papaya plantation. In addition, we assessed heterospecific pollen transfer to the stigmatic loads of papaya and its effect on fruit and seed production. We found that papaya shared at least one pollinator species with the majority of the co-flowering plants. Despite this, heterospecific pollen transfer in cultivated papaya was low in open-pollinated flowers. Hand-pollination experiments suggest that heterospecific pollen transfer has no negative effect on fruit production or weight, but does reduce seed production. These results suggest that co-flowering plants offer valuable floral resources to pollinators that are shared with cultivated papaya with little or no cost in terms of heterospecific pollen transfer. Although HP reduced seed production, a reduced number of seeds per se are not negative, given that from an agronomic perspective the number of seeds does not affect the monetary value of the papaya fruit.

14.
MethodsX ; 5: 752-760, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30109198

RESUMO

Combination of digital X-ray with image processing techniques has the potential to extract useful information for healthcare professionals (physicians). From all the information that can be extracted from X-ray images, information concerning the human cervical vertebrae is relevant for the medical area. Therefore, in this work we present a simple enhanced region of interest (ROI) selection tool to select automatically the region that contains most of the information concerning to cervical vertebrae. The ROI-selection method reduces the size of a lateral or frontal digital X-ray by 30-60% without losing significance in the resulting image. This is achieved by an adjustment of dimensions in the image while the cervical area is preserved. Moreover, the visual quality is improved by performing a contrast enhancement in the region of interest. •Automatic threshold selection is computationally more efficient than traditional image segmentation techniques.•Reduce size in comparison with original image (enhancing ROI).•Independence of depth gray scale space.

15.
Salud(i)ciencia (Impresa) ; 22(2): 140-146, ago. 2016. tab.
Artigo em Espanhol | BINACIS, LILACS | ID: biblio-1102656

RESUMO

Blood transfusion as well as blood conservation strategies are the basis of so-called transfusion medicine, which is founded on the multidisciplinary work of anaesthesiologists, surgeons, haematologists, internists, etc. Its main objective is to avoid unnecessary transfusions. It is out of the question that a knowledge of transfusion indications, with the application of physiological triggers for red blood cells and the use of viscoelastic test-based guidelines for plasma and platelets, forces us to stay constantly abreast of the latest guidelines in this field. It is true that the blood products transfused today are the safest ever, although a zero-risk situation is impossible to reach. So, it is always important to keep in mind, as an essential part of transfusion medicine, a balance between risk and benefits in the indication of every single hemoderivate we prescribe. Taking into account the need for better criteria in the final transfusion decision, trying to use every resource available to minimise allogenic blood administration (also avoiding infra-transfusion), the concept of "patient blood management" has been developed. Its main objective for the surgical patient is to optimise preparation in the preoperative period, to minimise blood loss and bleeding during surgery, as well as to optimise the physiological tolerance of anaemia in the postoperative period


La transfusión de hemoderivados y sus técnicas de ahorro son la base de la medicina transfusional, que se fundamenta en el trabajo multidisciplinario de anestesiólogos, cirujanos, hematólogos, internistas, entre otros. Su objetivo esencial es disminuir o evitar las denominadas transfusiones innecesarias. No cabe duda de que el conocimiento de las indicaciones de administración de cada uno de los hemoderivados, con la aplicación de los triggers fisiológicos cuando se hace referencia a los concentrados de hematíes, o de la monitorización con pruebas de viscoelasticidad cuando se habla de la transfusión de hemostáticos, hacen que debamos ser conocedores de las nuevas tendencias decisionales en este campo. La sangre que se transfunde en el momento actual es la más segura que hemos tenido nunca, pero es imposible llegar al "riesgo cero", por lo que siempre es necesario tener en cuenta, como parte de la medicina transfusional, el equilibrio entre riesgo y beneficio en la indicación de cada uno de los hemoderivados que administramos. A partir de la premisa de transfundir con mejor criterio, tratando de emplear todos los recursos para minimizar la transfusión de sangre alogénica sin entrar en la infratransfusión, se desarrolla el concepto de "patient blood management", cuya esencia es la óptima preparación del paciente, la minimización del sangrado y las pérdidas hemáticas durante la cirugía y el aprovechamiento y la optimización de la reserva fisiológica de cada paciente en el posoperatorio


Assuntos
Transfusão de Sangue , Hemoderivados , Medicina Transfusional , Hematologia
16.
Plant Physiol ; 170(2): 989-99, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26662603

RESUMO

Nitrogen is an essential soil nutrient for plants, and lack of nitrogen commonly limits plant growth. Soil nitrogen is typically available to plants in two inorganic forms: nitrate and ammonium. To better understand how nitrate and ammonium differentially affect plant metabolism and development, we performed transcriptional profiling of the shoots of ammonium-supplied and nitrate-supplied Arabidopsis (Arabidopsis thaliana) plants. Seven genes encoding class III glutaredoxins were found to be strongly and specifically induced by nitrate. RNA silencing of four of these glutaredoxin genes (AtGRXS3/4/5/8) resulted in plants with increased primary root length (approximately 25% longer than the wild type) and decreased sensitivity to nitrate-mediated inhibition of primary root growth. Increased primary root growth is also a well-characterized phenotype of many cytokinin-deficient plant lines. We determined that nitrate induction of glutaredoxin gene expression was dependent upon cytokinin signaling and that cytokinins could activate glutaredoxin gene expression independent of plant nitrate status. In addition, crosses between "long-root" cytokinin-deficient plants and "long-root" glutaredoxin-silenced plants generated hybrids that displayed no further increase in primary root length (i.e. epistasis). Collectively, these findings suggest that AtGRXS3/4/5/8 operate downstream of cytokinins in a signal transduction pathway that negatively regulates plant primary root growth in response to nitrate. This pathway could allow Arabidopsis to actively discriminate between different nitrogen sources in the soil, with the preferred nitrogen source, nitrate, acting to suppress primary root growth (vertical dimension) in concert with its well-characterized stimulatory effect on lateral root growth (horizontal dimension).


Assuntos
Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Glutarredoxinas/metabolismo , Nitratos/farmacologia , Raízes de Plantas/crescimento & desenvolvimento , Compostos de Amônio/farmacologia , Arabidopsis/efeitos dos fármacos , Citocininas/metabolismo , Epistasia Genética/efeitos dos fármacos , Inativação Gênica/efeitos dos fármacos , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/metabolismo , Brotos de Planta/efeitos dos fármacos , Brotos de Planta/genética , Plantas Geneticamente Modificadas , Transdução de Sinais/efeitos dos fármacos , Transcriptoma/efeitos dos fármacos , Transcriptoma/genética , Regulação para Cima/efeitos dos fármacos
17.
J Sci Food Agric ; 96(5): 1643-7, 2016 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-26009839

RESUMO

BACKGROUND: Anthocyanins are the main compounds responsible for the colour of red wines and therefore it may be important to evaluate the content of the aforesaid secondary metabolites during grape ripening due to the crucial importance to determine wine colour. Nowadays, there is a growing demand of rapid and non-destructive analytical tools for analysing grapes, such as the emerging hyperspectral analysis. RESULTS: The hyperspectral images of intact grapes (Vitis vinifera L. cv. Tempranillo, Graciano, Garnacha and Mazuelo red grape from vineyards located in the D.O.Ca. Rioja at two different developmental stages) were recorded using a near infrared hyperspectral imaging device (900-1700 nm). Reference values of anthocyanins were obtained by HPLC-DAD. Calibrations were performed by modified partial least squares regression and present a good potential (coefficient of determination of 0.72 and standard error of cross-validation values of 0.78 and 0.70 mg per grape for total and non-acylated anthocyanins respectively). CONCLUSION: The procedure reported here presents a good potential for a fast and reasonably inexpensive screening of these compounds in intact single berries. Moreover, the heterogeneity of anthocyanins within the same ripeness stage could be evaluated using this non-detructive tool.


Assuntos
Antocianinas/química , Análise de Alimentos , Espectroscopia de Luz Próxima ao Infravermelho/métodos , Vitis/química
18.
PLoS One ; 10(8): e0132671, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26241962

RESUMO

Plant diversity can influence predators and omnivores and such effects may in turn influence herbivores and plants. However, evidence for these ecological feedbacks is rare. We evaluated if the effects of tree species (SD) and genotypic diversity (GD) on the abundance of different guilds of insect herbivores associated with big-leaf mahogany (Swietenia macrophylla) were contingent upon the protective effects of ants tending extra-floral nectaries of this species. This study was conducted within a larger experiment consisting of mahogany monocultures and species polycultures of four species and -within each of these two plot types- mahogany was represented by either one or four maternal families. We selected 24 plots spanning these treatment combinations, 10 mahogany plants/plot, and within each plot experimentally reduced ant abundance on half of the selected plants, and surveyed ant and herbivore abundance. There were positive effects of SD on generalist leaf-chewers and sap-feeders, but for the latter group this effect depended on the ant reduction treatment: SD positively influenced sap-feeders under ambient ant abundance but had no effect when ant abundance was reduced; at the same time, ants had negative effects on sap feeders in monoculture but no effect in polyculture. In contrast, SD did not influence specialist stem-borers or leaf-miners and this effect was not contingent upon ant reduction. Finally, GD did not influence any of the herbivore guilds studied, and such effects did not depend on the ant treatment. Overall, we show that tree species diversity influenced interactions between a focal plant species (mahogany) and ants, and that such effects in turn mediated plant diversity effects on some (sap-feeders) but not all the herbivores guilds studied. Our results suggest that the observed patterns are dependent on the combined effects of herbivore identity, diet breadth, and the source of plant diversity.


Assuntos
Formigas/fisiologia , Comportamento Animal , Ecossistema , Herbivoria/fisiologia , Insetos/fisiologia , Árvores , Animais , Biota , Florestas , Variação Genética , Genótipo , Controle de Insetos , Insetos/classificação , Meliaceae/genética , México , Dispersão Vegetal , Folhas de Planta , Especificidade da Espécie , Árvores/classificação , Árvores/genética
19.
Science ; 346(6213): 1256688, 2014 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-25430773

RESUMO

Fungi play major roles in ecosystem processes, but the determinants of fungal diversity and biogeographic patterns remain poorly understood. Using DNA metabarcoding data from hundreds of globally distributed soil samples, we demonstrate that fungal richness is decoupled from plant diversity. The plant-to-fungus richness ratio declines exponentially toward the poles. Climatic factors, followed by edaphic and spatial variables, constitute the best predictors of fungal richness and community composition at the global scale. Fungi show similar latitudinal diversity gradients to other organisms, with several notable exceptions. These findings advance our understanding of global fungal diversity patterns and permit integration of fungi into a general macroecological framework.


Assuntos
Fungos/classificação , Fungos/fisiologia , Microbiologia do Solo , Solo , Código de Barras de DNA Taxonômico , Florestas , Fungos/genética , Geografia , Pradaria , Tundra
20.
PLoS One ; 9(10): e111742, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25347818

RESUMO

Studies of the effects of patch size and isolation on plant species density have yielded contrasting results. However, much of the available evidence comes from relatively recent anthropogenic forest fragments which have not reached equilibrium between extinction and immigration. This is a critical issue because the theory clearly states that only when equilibrium has been reached can the number of species be accurately predicted by habitat size and isolation. Therefore, species density could be better predicted by patch size and isolation in an ecosystem that has been fragmented for a very long time. We tested whether patch area, isolation and other spatial variables explain variation among forest patches in plant species density in an ecosystem where the forest has been naturally fragmented for long periods of time on a geological scale. Our main predictions were that plant species density will be positively correlated with patch size, and negatively correlated with isolation (distance to the nearest patch, connectivity, and distance to the continuous forest). We surveyed the vascular flora (except lianas and epiphytes) of 19 forest patches using five belt transects (50×4 m each) per patch (area sampled per patch = 0.1 ha). As predicted, plant species density was positively associated (logarithmically) with patch size and negatively associated (linearly) with patch isolation (distance to the nearest patch). Other spatial variables such as patch elevation and perimeter, did not explain among-patch variability in plant species density. The power of patch area and isolation as predictors of plant species density was moderate (together they explain 43% of the variation), however, a larger sample size may improve the explanatory power of these variables. Patch size and isolation may be suitable predictors of long-term plant species density in terrestrial ecosystems that are naturally and anthropogenically fragmented.


Assuntos
Biodiversidade , Biomassa , Florestas , Modelos Biológicos , Árvores/classificação , Árvores/crescimento & desenvolvimento
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