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1.
Arch Insect Biochem Physiol ; 112(2): e21981, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36331499

RESUMO

Bemisia tabaci is a species complex consisting of various genetically different cryptic species worldwide. To understand the genetic characteristics and geographic distribution of cryptic species of B. tabaci in Asia, we conducted an extensive collection of B. tabaci samples in ten Asian countries (Bangladesh, Indonesia, Japan, Korea, Myanmar, Nepal, Philippines, Singapore, Taiwan, and Vietnam) from 2013 to 2020 and determined 56 different partial sequences of mitochondrial cytochrome oxidase subunit I (COI) DNA. In addition, information on 129 COI sequences of B. tabaci identified from 16 Asian countries was downloaded from the GenBank database. Among the total 185 COI sequences of B. tabaci, the sequence variation reached to 19.68%. In addition, there were 31 cryptic species updated from 16 countries in Asia, that is, Asia I, Asia I India, Asia II (1-13), Asia III, Asia IV, Asia V, China 1-6, MEAM (1, 2, K), MED, Australia/Indonesia, Japan (1 and 2). Further, MED cryptic species consisted of 2 clades, Q1 and Q2. This study provides updated information to understand the genetic variation and geographic diversity of B. tabaci in Asia.


Assuntos
Hemípteros , Mitocôndrias , Animais , Filogenia , Ásia , China , Hemípteros/genética , Variação Genética
2.
J Formos Med Assoc ; 121(1 Pt 2): 335-341, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34024719

RESUMO

BACKGROUND/PURPOSE: To the best of our knowledge, no studies have examined longitudinal changes in the accessibility of suicide-related content on Chinese-language websites. We investigated changes between 2016 and 2019 in suicide-related materials likely to be accessed by individuals through websites in Taiwan. METHODS: In March 2019, we searched the Taiwanese versions of Google and Yahoo! using six suicide-related terms and compared the results to a search performed in 2016. Website characteristics (e.g., pro- or anti-suicide) generated by various keywords were calculated and compared in 2016 and 2019. RESULTS: The number of anti-suicide websites exceeded that of pro-suicide websites in 2016 and 2019. Between 2016 and 2019, the proportion of pro-suicide sites decreased slightly from 16.3% (61 out of 375 sites) to 12.3% (51 out of 417 sites) (p = 0.10). User-generated webpages constituted the primary source of pro-suicide content at both time points. Over the same period, the proportion of pro-suicide information on internet forums decreased from 59.1% to 17.8% (p < 0.001); by contrast, pro-suicide content on news websites increased significantly, from 1.9% to 11.3% (p = 0.005). Searches with the term "painless suicide" were more likely to yield pro-suicide websites and less likely to generate anti-suicide ones than searches with "suicide" in both 2016 and 2019. CONCLUSION: Harmful suicide-related information circulating on websites remained easily accessible to internet users in Taiwan, particularly through user-generated and news websites. Proper site moderation and implementation of online suicide reporting guidelines are still warranted.


Assuntos
Suicídio , Humanos , Taiwan
3.
Commun Chem ; 7(1): 91, 2024 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-38643239

RESUMO

Isofagomine (IFG) and its analogues possess promising glycosidase inhibitory activities. However, a flexible synthetic strategy toward both C5a-functionalized IFGs remains to be explored. Here we show a practical synthesis of C5a-S and R aminomethyl IFG-based derivatives via the diastereoselective addition of cyanide to cyclic nitrone 1. Nitrone 1 was conveniently prepared on a gram scale and in high yield from inexpensive (-)-diethyl D-tartrate via a straightforward method, with a stereoselective Michael addition of a nitroolefin and a Nef reaction as key steps. A 268-membered library (134 × 2) of the C5a-functionalized derivatives was submitted to enzyme- or cell-based bio-evaluations, which resulted in the identification of a promising ß-glucocerebrosidase (GCase) stabilizer demonstrating a 2.7-fold enhancement at 25 nM in p.Asn370Ser GCase activity and a 13-fold increase at 1 µM in recombinant human GCase activity in Gaucher cell lines.

4.
Insects ; 14(11)2023 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-37999069

RESUMO

Tomato yellow leaf curl disease, caused by a group of closely related tomato yellow leaf curl viruses, is a major threat to tomato cultivation worldwide. These viruses are primarily transmitted by the sweet potato whitefly (Bemisia tabaci) in a persistent-circulative manner, wherein the virus circulates in the body of B. tabaci and infects its tissues. The complex relationship between viruses and whiteflies significantly influences virus transmission, with studies showing varying effects of the former on the life history and feeding preference of the latter. Whether these effects are direct or indirect, and whether they are negative, neutral, or positive, appears to depend on the specific interactions between virus and whitefly species. The tomato yellow leaf curl Thailand virus (TYLCTHV) and the tomato leaf curl Taiwan virus (ToLCTV) are two prevalent begomoviruses in fields in Taiwan. This study examined the direct and indirect effects of TYLCTHV and ToLCTV on the life history traits (longevity, fecundity, nymph survival, and nymph developmental time) and feeding preference of B. tabaci Middle East-Asia Minor 1 (MEAM1). The results revealed that TYLCTHV had no effects on these life history traits or the feeding preference of MEAM1 whiteflies. Although ToLCTV did not directly affect the longevity and fecundity of MEAM1 whiteflies, their fecundity and the nymph developmental time were negatively affected by feeding on ToLCTV-infected plants. In addition, ToLCTV infection also altered the feeding preference of MEAM1 whiteflies. The different effects of virus infection may contribute to the lower prevalence of ToLCTV compared to TYLCTHV in fields in Taiwan.

5.
Soc Psychiatry Psychiatr Epidemiol ; 47(2): 215-21, 2012 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-21165595

RESUMO

PURPOSE: To examine if widespread media reporting of the suicide of a young female singer by charcoal burning increased suicide rates, and to examine whether the suicide induced a high risk of imitation suicide by this method among the young female group. METHODS: Poisson time series autoregression model was applied to examine the relative risk of overall and subgroup (age, gender and method) suicides during the 2-week period after the initiation of media reporting of the celebrity suicide. RESULTS: We found a significant increase (adjusted relative risk = 1.17, p = 0.04) in suicide deaths following media reporting of the celebrity suicide. The increase in suicides was particularly significant among female and young age groups. A marked increase in suicide by charcoal burning among females (adjusted relative risk = 1.44, p < 0.0001) was further observed. CONCLUSIONS: Detailed description of a specific suicide method following celebrity suicides may induce extensive modeling effect, attracting wider age/sex groups to model the method. Our finding provides further support for restraining media reporting of celebrity suicide in suicide prevention.


Assuntos
Pessoas Famosas , Comportamento Imitativo , Meios de Comunicação de Massa , Suicídio/psicologia , Adulto , Fatores Etários , Intoxicação por Monóxido de Carbono/mortalidade , Carvão Vegetal/intoxicação , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Risco , Fatores Sexuais , Suicídio/classificação , Suicídio/tendências , Taiwan/epidemiologia , Fatores de Tempo , Adulto Jovem
6.
Crisis ; 43(5): 426-433, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34427456

RESUMO

Background: The differences in emotional reactions toward media reports of celebrity suicides between distressed and non-distressed individuals have rarely been explored. Aim: We aimed to explore differences in reaction patterns to the news coverage of a celebrity's suicide between distressed and nondistressed individuals in Taiwan. Method: We conducted an Internet survey to assess the impact of the news coverage of a celebrity's suicide. A series of χ2 tests, Spearman's rank correlations, and logistic regression analyses were performed to compare the differences in emotional involvement and psychological impact after exposure to suicide news between distressed and nondistressed individuals. Results: A total of 1,258 Internet users responded to the survey (236 men and 1,020 women). Compared with nondistressed individuals, distressed individuals (n = 537) were more likely to feel suicidal (11% vs. 2%, p < .001) after reading the news. They were less willing to seek help when in need (62% vs. 77%, p < .001). All the variables remained significant after adjustment for sociodemographic variables in regression analyses. Limitations: The Internet-based survey may suffer from selection bias. Conclusion: Extensive media reporting of suicide stories has a profound impact on readers, particularly on vulnerable groups. Responsible reporting of suicide incidents is crucial for suicide prevention.


Assuntos
Pessoas Famosas , Prevenção do Suicídio , Masculino , Humanos , Feminino , Taiwan/epidemiologia , Ideação Suicida , Emoções , Meios de Comunicação de Massa
7.
Front Plant Sci ; 13: 970941, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36247535

RESUMO

Plant viruses are responsible for the most devastating and commercially significant plant diseases, especially in tropical and subtropical regions. The genus begomovirus is the largest one in the family Geminiviridae, with a single-stranded DNA genome, either monopartite or bipartite. Begomoviruses are transmitted by insect vectors, such as Bemisia tabaci. Begomoviruses are the major causative agents of diseases in agriculture globally. Because of their diversity and mode of evolution, they are thought to be geographic specific. The emerging begomoviruses are of serious concern due to their increasing host range and geographical expansion. Several begomoviruses of Asiatic origin have been reported in Europe, causing massive economic losses; insect-borne transmission of viruses is a critical factor in virus outbreaks in new geographical regions. This review highlights crucial information regarding Asia's four emerging and highly destructive begomoviruses. We also provided information regarding several less common but still potentially important pathogens of different crops. This information will aid possible direction of future studies in adopting preventive measures to combat these emerging viruses.

8.
J Econ Entomol ; 104(5): 1480-5, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22066175

RESUMO

Many biotic and abiotic factors affect the transmission efficiency of vector-borne plant pathogens. Insect vector within-plant distribution and host tissue preference are known to affect pathogen acquisition and inoculation rates. In this study, we first investigated whether feeding tissue affects the transmission of Grapevine leafroll-associated virus 3 by Planococcus ficus (Signoret) (Hemiptera: Pseudococcidae) and the effect of mealybug within-plant distribution on virus transmission under greenhouse conditions. Results showed no significant effect on transmission efficiency after insect confinement on leaf blades, petioles or stems of virus source or healthy test plants for either acquisition or inoculation trials. Transmission efficiency of a single mealybug varied from 4 to 25% in those trials. Second, we tested whether leaf position affected transmission efficiency due to potentially variable virus populations within acquisition plant tissues. No significant differences of transmission rate among acquisition leaf position were observed, probably because there were no differences in the virus population within source tissues. Finally, we examined the seasonality of the virus in field-collected samples and found that GLRaV-3 prevalence varied along a growing season, such that GLRaV-3 translocated along expanding shoots to leaves. Similarly, mealybug populations are known to increase in spring, and then mealybugs spread to cordons and leaves. This coordination of spatial and temporal dynamics of the virus and its vector may increase the risk of GLRaV-3 transmission during late spring and early summer. Further integration of information about pathogen populations in plants, vector feeding behavior and vector population seasonality could lead to more effective management practices.


Assuntos
Closteroviridae/fisiologia , Hemípteros/virologia , Doenças das Plantas/virologia , Vitis/virologia , Animais , California , Ninfa/virologia , Folhas de Planta/fisiologia , Caules de Planta/fisiologia , Dinâmica Populacional , Estações do Ano , Vitis/fisiologia
9.
Insects ; 12(11)2021 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-34821776

RESUMO

Aphids are prominent phloem-feeding insect pests. Myzus persicae and Acyrthosiphon pisum are generalist and specialist species, respectively. In this study, these two aphid species were used to investigate host acceptance and plant resistance to aphid feeding. M.persicae survived and reproduced on rape (Brassica rapa), but few individuals (9%) survived on faba bean (Vicia faba). A.pisum survived and reproduced on faba bean, but no A.pisum survived on rape. The probing and feeding behavior of M. persicae and A. pisum on rape and faba bean was examined using an electrical penetration graph (EPG) technique. The results demonstrated the feeding preferences of these two aphid species. The EPG results suggest that the resistance of faba bean to M. persicae and that of rape to A. pisum are likely residing in the phloem and mesophyll tissues, respectively. Due to the distinct probing and feeding behaviors, specialist and generalist aphids would have different impacts on the epidemiology of plant viral diseases. The findings can be applied to the management of viral diseases transmitted by specialist or generalist aphids in crop production.

10.
Viruses ; 13(8)2021 07 23.
Artigo em Inglês | MEDLINE | ID: mdl-34452299

RESUMO

Tomato (Solanum lycopersicum) is an important economic crop worldwide. However, tomato production is jeopardized by the devastating tomato yellow leaf curl disease caused by whitefly-transmitted begomoviruses (WTBs). In this study, we evaluated the efficacy of our previously developed plant antiviral immunity inducer, fungal F8-culture filtrate, on tomato to combat tomato yellow leaf curl Thailand virus (TYLCTHV), the predominant WTB in Taiwan. Our results indicated that F8-culture filtrate treatment induced strong resistance, did not reduce the growth of tomato, and induced prominent resistance against TYLCTHV both in the greenhouse and in the field. Among TYLCTHV-inoculated Yu-Nu tomato grown in the greenhouse, a greater percentage of plants treated with F8-culture filtrate (43-100%) were healthy-looking compared to the H2O control (0-14%). We found that TYLCTHV cannot move systemically only on the F8-culture filtrate pretreated healthy-looking plants. Tracking the expression of phytohormone-mediated immune maker genes revealed that F8-culture filtrate mainly induced salicylic acid-mediated plant immunity. Furthermore, callose depositions and the expression of the pathogen-induced callose synthase gene, POWDERY MILDEW RESISTANT 4 were only strongly induced by TYLCTHV on tomato pretreated with F8-culture filtrate. This study provides an effective way to induce tomato resistance against TYLCTHV.


Assuntos
Begomovirus/imunologia , Resistência à Doença , Doenças das Plantas/imunologia , Doenças das Plantas/virologia , Imunidade Vegetal , Solanum lycopersicum/virologia , Trichosporon , Animais , Begomovirus/fisiologia , Meios de Cultura , Genes de Plantas , Glucanos/metabolismo , Hemípteros/virologia , Solanum lycopersicum/genética , Solanum lycopersicum/crescimento & desenvolvimento , Solanum lycopersicum/imunologia , Trichosporon/crescimento & desenvolvimento
11.
Insects ; 12(2)2021 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-33672688

RESUMO

Viruses that cause tomato yellow leaf curl disease are part of a group of viruses of the genus Begomovirus, family Geminiviridae. Tomato-infecting begomoviruses cause epidemics in tomato crops in tropical, subtropical, and Mediterranean climates, and they are exclusively transmitted by Bemisia tabaci in the field. The objective of the present study was to examine the transmission biology of the tomato yellow leaf curl Thailand virus (TYLCTHV) by B. tabaci, including virus-infected tissues, virus translocation, virus replication, and transovarial transmission. The results demonstrated that the virus translocates from the alimentary gut to the salivary glands via the hemolymph, without apparent replication when acquired by B. tabaci. Furthermore, the virus was detected in 10% of the first-generation progeny of viruliferous females, but the progeny was unable to cause the viral infection of host plants. There was no evidence of transovarial transmission of TYLCTHV in B. tabaci. When combined with the current literature, our results suggest that B. tabaci transmits TYLCTHV in a persistent-circulative mode. The present study enhances our understanding of virus-vector interaction and the transmission biology of TYLCTHV in B. tabaci.

12.
Front Microbiol ; 12: 684092, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34093511

RESUMO

The bacterial genus Xylella contains plant pathogens that are major threats to agriculture in America and Europe. Although extensive research was conducted to characterize different subspecies of Xylella fastidiosa (Xf), comparative analysis at above-species levels was lacking due to the unavailability of appropriate data sets. Recently, a bacterium that causes pear leaf scorch (PLS) in Taiwan was described as the second Xylella species (i.e., Xylella taiwanensis; Xt). In this work, we report the complete genome sequence of Xt type strain PLS229T. The genome-scale phylogeny provided strong support that Xf subspecies pauca (Xfp) is the basal lineage of this species and Xylella was derived from the paraphyletic genus Xanthomonas. Quantification of genomic divergence indicated that different Xf subspecies share ∼87-95% of their chromosomal segments, while the two Xylella species share only ∼66-70%. Analysis of overall gene content suggested that Xt is most similar to Xf subspecies sandyi (Xfs). Based on the existing knowledge of Xf virulence genes, the homolog distribution among 28 Xylella representatives was examined. Among the 11 functional categories, those involved in secretion and metabolism are the most conserved ones with no copy number variation. In contrast, several genes related to adhesins, hydrolytic enzymes, and toxin-antitoxin systems are highly variable in their copy numbers. Those virulence genes with high levels of conservation or variation may be promising candidates for future studies. In summary, the new genome sequence and analysis reported in this work contributed to the study of several important pathogens in the family Xanthomonadaceae.

13.
Microb Genom ; 7(12)2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34898423

RESUMO

The economically important plant pathogen Xylella fastidiosa has been reported in multiple regions of the globe during the last two decades, threatening a growing list of plants. Particularly, X. fastidiosa subspecies fastidiosa causes Pierce's disease (PD) of grapevines, which is a problem in the USA, Spain, and Taiwan. In this work, we studied PD-causing subsp. fastidiosa populations and compared the genome sequences of 33 isolates found in Central Taiwan with 171 isolates from the USA and two from Spain. Phylogenetic relationships, haplotype networks, and genetic diversity analyses confirmed that subsp. fastidiosa was recently introduced into Taiwan from the Southeast USA (i.e. the PD-I lineage). Recent core-genome recombination events were detected among introduced subsp. fastidiosa isolates in Taiwan and contributed to the development of genetic diversity. The genetic diversity observed includes contributions through recombination from unknown donors, suggesting that higher genetic diversity exists in the region. Nevertheless, no recombination event was detected between X. fastidiosa subsp. fastidiosa and the endemic sister species Xylella taiwanensis, which is the causative agent of pear leaf scorch disease. In summary, this study improved our understanding of the genetic diversity of an important plant pathogenic bacterium after its invasion to a new region.


Assuntos
Variação Genética , Vitis/microbiologia , Sequenciamento Completo do Genoma/métodos , Xylella/classificação , Genoma Bacteriano , Haplótipos , Filogenia , Filogeografia , Doenças das Plantas/microbiologia , Espanha , Taiwan , Estados Unidos , Xylella/genética , Xylella/isolamento & purificação
14.
PLoS One ; 16(3): e0247500, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33657150

RESUMO

Thrips and thrips-transmitted tospoviruses cause significant losses in crop yields worldwide. The melon thrips (Thrips palmi) is not only a pest of cucurbit crops, but also a vector that transmits tospoviruses, such as the watermelon silver mottle virus (WSMoV). Vector transmission of tospoviruses has been well studied in the tomato spotted wilt virus (TSWV)-Frankliniella occidentalis model system; however, until now the transmission mode of WSMoV by T. palmi has not been sufficiently examined. The results of the transmission assays suggest that T. palmi transmits WSMoV in a persistent manner, and that the virus is mainly transmitted by adults, having been ingested at the first-instar larval stage. Complementary RNAs corresponding to the NSm and NSs genes of WSMoV were detected in viruliferous thrips by reverse transcription-polymerase chain reaction; NSs protein was also detected in viruliferous thrips by western blotting, verifying the replication of WSMoV in T. palmi. Furthermore, we demonstrated that in thrips infected with WSMoV at the first-instar larval stage, the virus eventually infected various tissues of the adult thrips, including the primary salivary glands. Taken together, these results suggest that T. palmi transmits WSMoV in a persistent-propagative mode. The results of this study make a significant contribution to the understanding of the transmission biology of tospoviruses in general.


Assuntos
Citrullus/virologia , Doenças das Plantas/virologia , Tisanópteros/virologia , Tospovirus/genética , Animais , Feminino , Larva/virologia , Masculino , RNA Viral/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Glândulas Salivares/virologia , Replicação Viral
15.
Phytopathology ; 100(8): 830-4, 2010 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-20626287

RESUMO

To understand ecological factors mediating the spread of insect-borne plant pathogens, vector species for these pathogens need to be identified. Grapevine leafroll disease is caused by a complex of phylogenetically related closteroviruses, some of which are transmitted by insect vectors; however, the specificities of these complex virus-vector interactions are poorly understood thus far. Through biological assays and phylogenetic analyses, we studied the role of vector-pathogen specificity in the transmission of several grapevine leafroll-associated viruses (GLRaVs) by their mealybug vectors. Using plants with multiple virus infections, several virus species were screened for vector transmission by the mealybug species Planococcus ficus and Pseudococcus longispinus. We report that two GLRaVs (-4 and -9), for which no vector transmission evidence was available, are mealybug-borne. The analyses performed indicated no evidence of mealybug-GLRaV specificity; for example, different vector species transmitted GLRaV-3 and one vector species, Planococcus ficus, transmitted five GLRaVs. Based on available data, there is no compelling evidence of vector-virus specificity in the mealybug transmission of GLRaVs. However, more studies aimed at increasing the number of mealybug species tested as vectors of different GLRaVs are necessary. This is especially important given the increasing importance of grapevine leafroll disease spread by mealybugs in vineyards worldwide.


Assuntos
Closteroviridae/fisiologia , Hemípteros/virologia , Interações Hospedeiro-Parasita , Insetos Vetores/virologia , Vitis/virologia , Animais , Doenças das Plantas/virologia , Especificidade da Espécie , Vitis/parasitologia
16.
Insects ; 11(8)2020 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-32759662

RESUMO

Plant sap-sucking insects commonly have established mutualistic relationships with endosymbiotic bacteria that can provide nutrients lacking in their diet. Bemisia tabaci harbors one primary endosymbiont, Portiera aleyrodidarum, and up to seven secondary endosymbionts, including Hamiltonella defensa and Rickettsia sp. Portiera aleyrodidarum is already known to play a critical role in providing necessary nutrients for B. tabaci. In the present study, the relationship among B. tabaci, its primary endosymbiont, and the host plant were examined through the effects of host plant shifting and acclimation. Bemisia tabaci was transferred from Chinese kale to four different host plants, and the effects on both its performance and the expression levels of nutrient-related genes of P. aleyrodidarum were analyzed. The results showed that host shifting from Chinese kale to cotton plants led to a decrease in the performance of B. tabaci in the first generation, which was restored after 10 generations of acclimation. Furthermore, the expression levels of essential amino acid biosynthesis genes of P. aleyrodidarum were found to be differentially regulated after B. tabaci had acclimated to the cotton plants. Host plant shifting and acclimation to cucumber, poinsettia, and tomato plants did not affect the fecundity of B. tabaci and the expression levels of most examined genes. We speculate that P. aleyrodidarum may help B. tabaci improve its performance and acclimate to new hosts and that P. aleyrodidarum has a close nutritional relationship with its host during host plant acclimation.

17.
Mol Ecol ; 18(1): 136-46, 2009 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-19037897

RESUMO

Emerging diseases are increasing in incidence; therefore, understanding how pathogens are introduced into new regions and cause epidemics is of importance for the development of strategies that may hinder their spread. We used molecular data to study how a vector-borne banana virus, Banana bunchy top virus (BBTV), spread in Hawaii after it was first detected in 1989. Our analyses suggest that BBTV was introduced once into Hawaii, on the island of Oahu. All other islands were infected with isolates originating from Oahu, suggesting that movement of contaminated plant material was the main driving factor responsible for interisland spread of BBTV. The rate of mutation inferred by the phylogenetic analysis (1.4 x 10(-4) bp/year) was similar to that obtained in an experimental evolution study under greenhouse conditions (3.9 x 10(-4) bp/year). We used these values to estimate the number of infections occurring under field conditions per year. Our results suggest that strict and enforced regulations limiting the movement of banana plant material among Hawaiian islands could have reduced interisland spread of this pathogen.


Assuntos
Babuvirus/genética , Evolução Molecular , Musa/virologia , Doenças das Plantas/virologia , Teorema de Bayes , DNA Viral/genética , Genética Populacional , Geografia , Havaí , Cadeias de Markov , Método de Monte Carlo , Mutação , Filogenia
18.
Insects ; 10(10)2019 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-31614679

RESUMO

The Drosophila melanogaster sigma virus, a member of the Rhabdoviridae family, specifically propagates itself in D. melanogaster. It contains six genes in the order of 3'-N-P-X-M-G-L-5'. The sigma virus is the only arthropod-specific virus of the Rhabdoviridae family. Sigma-virus-infected Drosophila may suffer from irreversible paralysis when exposed to a high CO2 concentration, but generally, no other symptoms are reported. A recent study reported that host gene expression in immune pathways was not changed in sigma-virus-infected Drosophila, which does not necessarily suggest that they are not involved in virus-host interactions. The present study aimed to identify host genes associated with sigma virus replication. Immune pathways JAK-STAT and IMD were selected for detailed study. The results showed that the genome copy number of the sigma virus increased after knocking down the immune pathway genes domeless and PGRP-LC in Drosophila S2 cells. The knocking down of domeless and PGRP-LC significantly up-regulated the expression of the L gene compared to the other viral genes. We propose that the immune pathways respond to sigma virus infection by altering L expression, hence suppressing viral replication. This effect was further tested in vivo, when D. melanogaster individuals injected with dsdome and dsPGRP-LC showed not only an increase in sigma virus copy number, but also a reduced survival rate when treated with CO2. Our study proved that host immunity influences viral replication, even in persistent infection. Knocking down the key components of the immune process deactivates immune controls, thus facilitating viral expression and replication. We propose that the immunity system of D. melanogaster regulates the replication of the sigma virus by affecting the L gene expression. Studies have shown minimal host-virus interaction in persistent infection. However, our study demonstrated that the immunity continued to affect viral replication even in persistent infection because knocking down the key components of the immune process disabled the relevant immune controls and facilitated viral expression and replication.

19.
Appl Environ Microbiol ; 74(12): 3690-701, 2008 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-18424531

RESUMO

Xylella fastidiosa is a vector-borne, plant-pathogenic bacterium that causes disease in citrus (citrus variegated chlorosis [CVC]) and coffee (coffee leaf scorch [CLS]) plants in Brazil. CVC and CLS occur sympatrically and share leafhopper vectors; thus, determining whether X. fastidiosa isolates can be dispersed from one crop to another and cause disease is of epidemiological importance. We sought to clarify the genetic and biological relationships between CVC- and CLS-causing X. fastidiosa isolates. We used cross-inoculation bioassays and microsatellite and multilocus sequence typing (MLST) approaches to determine the host range and genetic structure of 26 CVC and 20 CLS isolates collected from different regions in Brazil. Our results show that citrus and coffee X. fastidiosa isolates are biologically distinct. Cross-inoculation tests showed that isolates causing CVC and CLS in the field were able to colonize citrus and coffee plants, respectively, but not the other host, indicating biological isolation between the strains. The microsatellite analysis separated most X. fastidiosa populations tested on the basis of the host plant from which they were isolated. However, recombination among isolates was detected and a lack of congruency among phylogenetic trees was observed for the loci used in the MLST scheme. Altogether, our study indicates that CVC and CLS are caused by two biologically distinct strains of X. fastidiosa that have diverged but are genetically homogenized by frequent recombination.


Assuntos
Citrus/microbiologia , Café/microbiologia , Variação Genética , Doenças das Plantas/microbiologia , Xylella/classificação , Xylella/genética , Brasil , Análise por Conglomerados , DNA Bacteriano/química , DNA Bacteriano/genética , Genótipo , Repetições de Microssatélites , Dados de Sequência Molecular , Filogenia , Recombinação Genética , Análise de Sequência de DNA , Xylella/isolamento & purificação , Xylella/fisiologia
20.
PLoS One ; 13(12): e0208538, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30532222

RESUMO

Thrips palmi is a widely distributed major agricultural pest in the tropics and subtropics, causing significant losses in cucurbit and solanaceous crops through feeding damage and transmission of tospoviruses. Thrips palmi is a vector of capsicum chlorosis virus (CaCV) in Australia. The present understanding of transmission biology and potential effects of CaCV on T. palmi is limited. To gain insights into molecular responses to CaCV infection, we performed RNA-Seq to identify thrips transcripts that are differentially-abundant during virus infection of adults. De-novo assembly of the transcriptome generated from whole bodies of T. palmi adults generated 166,445 contigs, of which ~24% contained a predicted open reading frame. We identified 1,389 differentially-expressed (DE) transcripts, with comparable numbers up- (708) and down-regulated (681) in virus-exposed thrips compared to non-exposed thrips. Approximately 59% of these DE transcripts had significant matches to NCBI non-redundant proteins (Blastx) and Blast2GO identified provisional functional categories among the up-regulated transcripts in virus-exposed thrips including innate immune response-related genes, salivary gland and/or gut-associated genes and vitellogenin genes. The majority of the immune-related proteins are known to serve functions in lysosome activity and melanisation in insects. Most of the up-regulated oral and extra-oral digestion-associated genes appear to be involved in digestion of proteins, lipids and plant cell wall components which may indirectly enhance the likelihood or frequency of virus transmission or may be involved in the regulation of host defence responses. Most of the down-regulated transcripts fell into the gene ontology functional category of 'structural constituent of cuticle'. Comparison to DE genes responsive to tomato spotted wilt virus in Frankliniella occidentalis indicates conservation of some thrips molecular responses to infection by different tospoviruses. This study assembled the first transcriptome in the genus Thrips and provides important data to broaden our understanding of networks of molecular interactions between thrips and tospoviruses.


Assuntos
Perfilação da Expressão Gênica , Tisanópteros/genética , Tisanópteros/virologia , Tospovirus/fisiologia , Animais , Anotação de Sequência Molecular , RNA Mensageiro/genética , Especificidade da Espécie
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