5,170 research outputs found

    Interplay between gut lymphatic vessels and microbiota

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    Lymphatic vessels play a distinctive role in draining fluid, molecules and even cells from interstitial and serosal spaces back to the blood circulation. Lymph vessels of the gut, and especially those located in the villi (called lacteals), not only serve this primary function, but are also responsible for the transport of lipid moieties absorbed by the intestinal mucosa and serve as a second line of defence against possible bacterial infections. Here, we briefly review the current knowledge of the general mechanisms allowing lymph drainage and propulsion and will focus on the most recent findings on the mutual relationship between lacteals and intestinal microbiota

    Management of Post-Harvest Anthracnose: Current Approaches and Future Perspectives

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    Anthracnose is a severe disease caused by Colletotrichum spp. on several crop species. Fungal infections can occur both in the field and at the post-harvest stage causing severe lesions on fruits and economic losses. Physical treatments and synthetic fungicides have traditionally been the preferred means to control anthracnose adverse effects; however, the urgent need to decrease the use of toxic chemicals led to the investigation of innovative and sustainable protection techniques. Evidence for the efficacy of biological agents and vegetal derivates has been reported; however, their introduction into actual crop protection strategies requires the solutions of several critical issues. Biotechnology-based approaches have also been explored, revealing the opportunity to develop innovative and safe methods for anthracnose management through genome editing and RNA interference technologies. Nevertheless, besides the number of advantages related to their use, e.g., the putative absence of adverse effects due to their high specificity, a number of aspects remain to be clarified to enable their introduction into Integrated Pest Management (IPM) protocols against Colletotrichum spp. disease

    Biology of Maconellicoccus hirsutus (Hemiptera: Pseudococcidae) on Hibiscus rosa-sinensis.

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    Maconellicoccus hirsutus Green, 1908 (Hemiptera: Pseudococcidae) is an introduced pest that threatens fruit and ornamental plant production in Brazil. Reported in Brazil for the first time in 2010, in the state of Roraima, M. hirsutus, has spread rapidly to other regions of the country. The objective of this study was to investigate the biology of M. hirsutus on Hibiscus rosa-sinensis L. (Malvaceae) leaves in laboratory conditions with climatic parameters similar to those of the Brazilian North and Northeast (27 ± 1 °C, 60 ± 10% relative humidity and 12 hours light and 12 hours dark). Eighty M. hirsutus nymphs were individualized on rooted H. rosa-sinensis leaves and their survival, mortality, sex ratio, and egg numbers per female emerged were recorded. Maconellicoccus hirsutus can have up to nine generations per year, taking 6.5 days to double its population size. The female numbers of this pest are about three times higher than those for its male counterparts, with 98 eggs per female and 97% viability. The survival curve of the species is type I, that is, mortality rates are higher in adulthood. Maconellicoccus hirsutus, especially, a pest of fruit trees and ornamental plants, presents great potential for population growth in Brazilian tropical conditions

    Population fluctuations in the pink hibiscus mealybug and its natural enemies in Annona squamosa (Annonaceae) in Roraima, Brazil.

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    <div><p>ABSTRACT Maconellicoccus hirsutus (Hemiptera, Pseudococcidae), a species of economic interest, especially for fruit plants, is expanding on the South American continent. Information about the population dynamics of this pest associated with control by natural enemies and cultural practices is fundamental for its management. Our objective was to study the population fluctuations in M. hirsutus and its natural enemies in a sugar-apple (Annona squamosa) orchard in Roraima, northern Brazil. Trees were evaluated monthly over a 12-month period. Infestation rates by M. hirsutus and its parasitism were also estimated for potential host plants around the study area. Highest infestation occurred in August and February-March. Alternative hosts were infested during the off-season, mainly fruit. Lacewings and the parasitoid Anagyrus kamali (Hymenoptera, Encyrtidae) were abundant natural enemies. Average parasitism by A. kamali in fruits was 50%, with highest rates in periods of greatest infestation by M. hirsutus. Fruitification pruning reduced M. hirsutus populations.</p></div

    Rna interference strategies for future management of plant pathogenic fungi: Prospects and challenges

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    Plant pathogenic fungi are the largest group of disease-causing agents on crop plants and represent a persistent and significant threat to agriculture worldwide. Conventional approaches based on the use of pesticides raise social concern for the impact on the environment and human health and alternative control methods are urgently needed. The rapid improvement and extensive implementation of RNA interference (RNAi) technology for various model and non-model organisms has provided the initial framework to adapt this post-transcriptional gene silencing technology for the management of fungal pathogens. Recent studies showed that the exogenous application of double-stranded RNA (dsRNA) molecules on plants targeting fungal growth and virulence-related genes provided disease attenuation of pathogens like Botrytis cinerea, Sclerotinia sclerotiorum and Fusarium graminearum in different hosts. Such results highlight that the exogenous RNAi holds great potential for RNAi-mediated plant pathogenic fungal disease control. Production of dsRNA can be possible by using either in-vitro or in-vivo synthesis. In this review, we describe exogenous RNAi involved in plant pathogenic fungi and discuss dsRNA production, formulation, and RNAi delivery methods. Potential challenges that are faced while developing a RNAi strategy for fungal pathogens, such as off-target and epigenetic effects, with their possible solutions are also discussed

    Animal models of hepatocellular carcinoma prevention

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    Hepatocellular carcinoma (HCC) is a deadly disease and therapeutic efficacy in advanced HCC is limited. Since progression of chronic liver disease to HCC involves a long latency period of a few decades, a significant window of therapeutic opportunities exists for prevention of HCC and improve patient prognosis. Nonetheless, there has been no clinical advancement in instituting HCC chemopreventive strategies. Some of the major challenges are heterogenous genetic aberrations of HCC, significant modulation of tumor microenvironment and incomplete understanding of HCC tumorigenesis. To this end, animal models of HCC are valuable tools to evaluate biology of tumor initiation and progression with specific insight into molecular and genetic mechanisms involved. In this review, we describe various animal models of HCC that facilitate effective ways to study therapeutic prevention strategies that have translational potential to be evaluated in a clinical context © 2019 by the authors. Licensee MDPI, Basel, Switzerland

    Induced expression of the Fragaria 7 ananassa Rapid alkalinization factor-33-like gene decreases anthracnose ontogenic resistance of unripe strawberry fruit stages

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    Rapid alkalinization factor (RALF) genes encode for ubiquitous small peptides that stimulate apoplastic alkalinization through interaction with malectin-like receptor kinase. RALF peptides may act as negative regulators of plant immune response, inhibiting the formation of the signal receptor complex for immune activation. Recently RALF homologues were identified in different fungal pathogen genomes contributing to host infection ability. Here, FaRALF-33-like gene expression was evaluated in strawberry fruits inoculated with Colletotrichum acutatum, Botrytis cinerea, or Penicillium expansum after 24 and 48 h post-infection. To investigate the role of FaRALF-33-like in strawberry susceptibility, transient transformation was used to overexpress it in white unripe fruits and silence it in red ripe fruits. Agroinfiltrated fruits were inoculated with C. acutatum and expression, and histological analysis of infection were performed. Silencing of FaRALF-33-like expression in C. acutatum-inoculated red fruits led to a delay in fruit colonization by the fungal pathogen, and infected tissues showed less penetrated infective hyphae than in wild-type fruits. In contrast, C. acutatum-inoculated white unripe fruits overexpressing the FaRALF-33-like gene decreased the ontogenic resistance of these fruits, leading to the appearance of disease symptoms and penetrated subcuticular hyphae, normally absent in white unripe fruits. The different response of transfected strawberry fruits to C. acutatum supports the hypothesis that the FaRALF-33-like gene plays an important role in the susceptibility of fruits to the fungal pathogen C. acutatum
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