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Sample records for alleles conferring resistance

  1. Initial frequency of alleles conferring resistance to Bacillus thuringiensis poplar in a field population of Chrysomela tremulae.

    PubMed Central

    Génissel, Anne; Augustin, Sylvie; Courtin, Claudine; Pilate, Gilles; Lorme, Philippe; Bourguet, Denis

    2003-01-01

    Globally, the estimated total area planted with transgenic plants producing Bacillus thuringiensis (Bt) toxins was 12 million hectares in 2001. The risk of target pests becoming resistant to these toxins has led to the implementation of resistance-management strategies. The efficiency and sustainability of these strategies, including the high-dose plus refuge strategy currently recommended for North American maize, depend on the initial frequency of resistance alleles. In this study, we estimated the initial frequencies of alleles conferring resistance to transgenic Bt poplars producing Cry3A in a natural population of the poplar pest Chrysomela tremulae (Coleoptera: Chrysomelidae). We used the F(2) screen method developed for detecting resistance alleles in natural pest populations. At least three parents of the 270 lines tested were heterozygous for a major Bt resistance allele. We estimated mean resistance-allele frequency for the period 1999-2001 at 0.0037 (95% confidence interval = 0.00045-0.0080) with a detection probability of 90%. These results demonstrate that (i) the F(2) screen method can be used to detect major alleles conferring resistance to Bt-producing plants in insects and (ii) the initial frequency of alleles conferring resistance to Bt toxin can be close to the highest theoretical values that are expected prior to the use of Bt plants if considering fitness costs and typical mutation rates. PMID:12737656

  2. Frequency of alleles conferring resistance to the Bt toxins Cry1Ac and Cry2Ab in Australian populations of Helicoverpa armigera (Lepidoptera: Noctuidae).

    PubMed

    Mahon, R J; Olsen, K M; Downes, S; Addison, S

    2007-12-01

    Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) is an important lepidopteran pest of cotton (Gossypium spp.) in Australia and the Old World. From 2002, F2 screens were used to examine the frequency of resistance alleles in Australian populations of H. armigera to Bacillus thuringiensis (Bt) CrylAc and Cry2Ab, the two insecticidal proteins present in the transgenic cotton Bollgard II. At that time, Ingard (expressing Cry1Ac) cotton had been grown in Australia for seven seasons, and Bollgard II was about to be commercially released. The principal objective of our study was to determine whether sustained exposure caused an elevated frequency of alleles conferring resistance to Cry1Ac in a species with a track record of evolving resistance to conventional insecticides. No major alleles conferring resistance to Cry1Ac were found. The frequency of resistance alleles for Cry1Ac was <0.0003, with a 95% credibility interval between 0 and 0.0009. In contrast, alleles conferring resistance to Cry2Ab were found at a frequency of 0.0033 (0.0017, 0.0055). The first isolation of this allele was found before the widespread deployment of Bollgard II. For both toxins the experiment-wise detection probability was 94.4%. Our results suggest that alleles conferring resistance to Cry1Ac are rare and that a relatively high baseline frequency of alleles conferring resistance to Cry2Ab existed before the introduction of Bt cotton containing this toxin.

  3. A stilbene synthase allele from a Chinese wild grapevine confers resistance to powdery mildew by recruiting salicylic acid signalling for efficient defence

    PubMed Central

    Jiao, Yuntong; Xu, Weirong; Duan, Dong; Wang, Yuejin; Nick, Peter

    2016-01-01

    Stilbenes are central phytoalexins in Vitis, and induction of the key enzyme stilbene synthase (STS) is pivotal for disease resistance. Here, we address the potential for breeding resistance using an STS allele isolated from Chinese wild grapevine Vitis pseudoreticulata (VpSTS) by comparison with its homologue from Vitis vinifera cv. ‘Carigane’ (VvSTS). Although the coding regions of both alleles are very similar (>99% identity on the amino acid level), the promoter regions are significantly different. By expression in Arabidopsis as a heterologous system, we show that the allele from the wild Chinese grapevine can confer accumulation of stilbenes and resistance against the powdery mildew Golovinomyces cichoracearum, whereas the allele from the vinifera cultivar cannot. To dissect the upstream signalling driving the activation of this promoter, we used a dual-luciferase reporter system in a grapevine cell culture. We show elevated responsiveness of the promoter from the wild grape to salicylic acid (SA) and to the pathogen-associated molecular pattern (PAMP) flg22, equal induction of both alleles by jasmonic acid (JA), and a lack of response to the cell death-inducing elicitor Harpin. This elevated SA response of the VpSTS promoter depends on calcium influx, oxidative burst by RboH, mitogen-activated protein kinase (MAPK) signalling, and JA synthesis. We integrate the data in the context of a model where the resistance of V. pseudoreticulata is linked to a more efficient recruitment of SA signalling for phytoalexin synthesis. PMID:27702992

  4. Characterization of a New Pm2 Allele Conferring Powdery Mildew Resistance in the Wheat Germplasm Line FG-1

    PubMed Central

    Ma, Pengtao; Xu, Hongxng; Li, Lihui; Zhang, Hongxia; Han, Guohao; Xu, Yunfeng; Fu, Xiaoyi; Zhang, Xiaotian; An, Diaoguo

    2016-01-01

    Powdery mildew has a negative impact on wheat production. Novel host resistance increases the diversity of resistance genes and helps to control the disease. In this study, wheat line FG-1 imported from France showed a high level of powdery mildew resistance at both the seedling and adult stages. An F2 population and F2:3 families from the cross FG-1 × Mingxian 169 both fit Mendelian ratios for a single dominant resistance gene when tested against multiple avirulent Blumeria tritici f. sp. tritici (Bgt) races. This gene was temporarily designated PmFG. PmFG was mapped on the multi-allelic Pm2 locus of chromosome 5DS using seven SSR, 10 single nucleotide polymorphism (SNP)-derived and two SCAR markers with the flanking markers Xbwm21/Xcfd81/Xscar112 (distal) and Xbwm25 (proximal) at 0.3 and 0.5 cM being the closest. Marker SCAR203 co-segregated with PmFG. Allelism tests between PmFG and documented Pm2 alleles confirmed that PmFG was allelic with Pm2. Line FG-1 produced a significantly different reaction pattern compared to other lines with genes at or near Pm2 when tested against 49 Bgt isolates. The PmFG-linked marker alleles detected by the SNP-derived markers revealed significant variation between FG-1 and other lines with genes at or near Pm2. It was concluded that PmFG is a new allele at the Pm2 locus. Data from seven closely linked markers tested on 31 wheat cultivars indicated opportunities for marker-assisted pyramiding of this gene with other genes for powdery mildew resistance and additional traits. PMID:27200022

  5. Characterization of a New Pm2 Allele Conferring Powdery Mildew Resistance in the Wheat Germplasm Line FG-1.

    PubMed

    Ma, Pengtao; Xu, Hongxng; Li, Lihui; Zhang, Hongxia; Han, Guohao; Xu, Yunfeng; Fu, Xiaoyi; Zhang, Xiaotian; An, Diaoguo

    2016-01-01

    Powdery mildew has a negative impact on wheat production. Novel host resistance increases the diversity of resistance genes and helps to control the disease. In this study, wheat line FG-1 imported from France showed a high level of powdery mildew resistance at both the seedling and adult stages. An F2 population and F2:3 families from the cross FG-1 × Mingxian 169 both fit Mendelian ratios for a single dominant resistance gene when tested against multiple avirulent Blumeria tritici f. sp. tritici (Bgt) races. This gene was temporarily designated PmFG. PmFG was mapped on the multi-allelic Pm2 locus of chromosome 5DS using seven SSR, 10 single nucleotide polymorphism (SNP)-derived and two SCAR markers with the flanking markers Xbwm21/Xcfd81/Xscar112 (distal) and Xbwm25 (proximal) at 0.3 and 0.5 cM being the closest. Marker SCAR203 co-segregated with PmFG. Allelism tests between PmFG and documented Pm2 alleles confirmed that PmFG was allelic with Pm2. Line FG-1 produced a significantly different reaction pattern compared to other lines with genes at or near Pm2 when tested against 49 Bgt isolates. The PmFG-linked marker alleles detected by the SNP-derived markers revealed significant variation between FG-1 and other lines with genes at or near Pm2. It was concluded that PmFG is a new allele at the Pm2 locus. Data from seven closely linked markers tested on 31 wheat cultivars indicated opportunities for marker-assisted pyramiding of this gene with other genes for powdery mildew resistance and additional traits.

  6. Discovery of a Novel er1 Allele Conferring Powdery Mildew Resistance in Chinese Pea (Pisum sativum L.) Landraces.

    PubMed

    Sun, Suli; Fu, Haining; Wang, Zhongyi; Duan, Canxing; Zong, Xuxiao; Zhu, Zhendong

    2016-01-01

    Pea powdery mildew, caused by Erysiphe pisi D.C., is an important disease worldwide. Deployment of resistant varieties is the main way to control this disease. This study aimed to screen Chinese pea (Pisum sativum L.) landraces resistant to E. pisi, and to characterize the resistance gene(s) at the er1 locus in the resistant landraces, and to develop functional marker(s) specific to the novel er1 allele. The 322 landraces showed different resistance levels. Among them, 12 (3.73%), 4 (1.24%) and 17 (5.28%) landraces showed immunity, high resistance and resistance to E. pisi, respectively. The other landraces appeared susceptible or highly susceptible to E. pisi. Most of the immune and highly resistant landraces were collected from Yunnan province. To characterize the resistance gene at the er1 locus, cDNA sequences of PsMLO1 gene were determined in 12 immune and four highly resistant accessions. The cDNAs of PsMLO1 from the immune landrace G0005576 produced three distinct transcripts, characterized by a 129-bp deletion, and 155-bp and 220-bp insertions, which were consistent with those of er1-2 allele. The PsMLO1 cDNAs in the other 15 resistant landraces produced identical transcripts, which had a new point mutation (T→C) at position 1121 of PsMLO1, indicating a novel er1 allele, designated as er1-6. This mutation caused a leucine to proline change in the amino acid sequence. Subsequently, the resistance allele er1-6 in landrace G0001778 was confirmed by resistance inheritance analysis and genetic mapping on the region of the er1 locus using populations derived from G0001778 × Bawan 6. Finally, a functional marker specific to er1-6, SNP1121, was developed using the high-resolution melting technique, which could be used in pea breeding via marker-assisted selection. The results described here provide valuable genetic information for Chinese pea landraces and a powerful tool for pea breeders.

  7. Prevalent HLA Class II Alleles in Mexico City Appear to Confer Resistance to the Development of Amebic Liver Abscess.

    PubMed

    Hernández, Eric G; Granados, Julio; Partida-Rodríguez, Oswaldo; Valenzuela, Olivia; Rascón, Edgar; Magaña, Ulises; Escamilla-Tilch, Mónica; López-Reyes, Alberto; Nieves-Ramírez, Miriam; González, Enrique; Morán, Patricia; Rojas, Liliana; Valadez, Alicia; Luna, Alexandra; Estrada, Francisco J; Maldonado, Carmen; Ximénez, Cecilia

    2015-01-01

    Amebiasis is an endemic disease and a public health problem throughout Mexico, although the incidence rates of amebic liver abscess (ALA) vary among the geographic regions of the country. Notably, incidence rates are high in the northwestern states (especially Sonora with a rate of 12.57/100,000 inhabitants) compared with the central region (Mexico City with a rate of 0.69/100,000 inhabitants). These data may be related to host genetic factors that are partially responsible for resistance or susceptibility. Therefore, we studied the association of the HLA-DRB1 and HLA-DQB1 alleles with resistance or susceptibility to ALA in two Mexican populations, one each from Mexico City and Sonora. Ninety ALA patients were clinically diagnosed by serology and sonography. Genomic DNA was extracted from peripheral blood mononuclear cells. To establish the genetic identity of both populations, 15 short tandem repeats (STRs) were analyzed with multiplexed PCR, and the allelic frequencies of HLA were studied by PCR-SSO using LUMINEX technology. The allele frequencies obtained were compared to an ethnically matched healthy control group (146 individuals). We observed that both affected populations differed genetically from the control group. We also found interesting trends in the population from Mexico City. HLA-DQB1*02 allele frequencies were higher in ALA patients compared to the control group (0.127 vs 0.047; p= 0.01; pc= NS; OR= 2.9, 95% CI= 1.09-8.3). The less frequent alleles in ALA patients were HLA-DRB1*08 (0.118 vs 0.238 in controls; p= 0.01; pc= NS; OR= 0.42, 95% CI= 0.19-0.87) and HLA-DQB1*04 (0.109 vs 0.214; p= 0.02; pc= NS; OR= 0.40, 95% CI= 0.20-0.94). The haplotype HLA-DRB1*08/-DQB1*04 also demonstrated a protective trend against the development of this disease (0.081 vs. 0.178; p=0.02; pc=NS; OR= 0.40, 95% CI= 0.16-0.93). These trends suggest that the prevalent alleles in the population of Mexico City may be associated with protection against the development of ALA.

  8. Prevalent HLA Class II Alleles in Mexico City Appear to Confer Resistance to the Development of Amebic Liver Abscess

    PubMed Central

    Hernández, Eric G.; Granados, Julio; Partida-Rodríguez, Oswaldo; Valenzuela, Olivia; Rascón, Edgar; Magaña, Ulises; Escamilla-Tilch, Mónica; López-Reyes, Alberto; Nieves-Ramírez, Miriam; González, Enrique; Morán, Patricia; Rojas, Liliana; Valadez, Alicia; Luna, Alexandra; Estrada, Francisco J.; Maldonado, Carmen; Ximénez, Cecilia

    2015-01-01

    Amebiasis is an endemic disease and a public health problem throughout Mexico, although the incidence rates of amebic liver abscess (ALA) vary among the geographic regions of the country. Notably, incidence rates are high in the northwestern states (especially Sonora with a rate of 12.57/100,000 inhabitants) compared with the central region (Mexico City with a rate of 0.69/100,000 inhabitants). These data may be related to host genetic factors that are partially responsible for resistance or susceptibility. Therefore, we studied the association of the HLA-DRB1 and HLA-DQB1 alleles with resistance or susceptibility to ALA in two Mexican populations, one each from Mexico City and Sonora. Ninety ALA patients were clinically diagnosed by serology and sonography. Genomic DNA was extracted from peripheral blood mononuclear cells. To establish the genetic identity of both populations, 15 short tandem repeats (STRs) were analyzed with multiplexed PCR, and the allelic frequencies of HLA were studied by PCR-SSO using LUMINEX technology. The allele frequencies obtained were compared to an ethnically matched healthy control group (146 individuals). We observed that both affected populations differed genetically from the control group. We also found interesting trends in the population from Mexico City. HLA-DQB1*02 allele frequencies were higher in ALA patients compared to the control group (0.127 vs 0.047; p= 0.01; pc= NS; OR= 2.9, 95% CI= 1.09-8.3). The less frequent alleles in ALA patients were HLA-DRB1*08 (0.118 vs 0.238 in controls; p= 0.01; pc= NS; OR= 0.42, 95% CI= 0.19-0.87) and HLA-DQB1*04 (0.109 vs 0.214; p= 0.02; pc= NS; OR= 0.40, 95% CI= 0.20-0.94). The haplotype HLA-DRB1*08/-DQB1*04 also demonstrated a protective trend against the development of this disease (0.081 vs. 0.178; p=0.02; pc=NS; OR= 0.40, 95% CI= 0.16-0.93). These trends suggest that the prevalent alleles in the population of Mexico City may be associated with protection against the development of ALA

  9. Frequency of alleles conferring resistance to the Bacillus thuringiensis toxins Cry1Ac and Cry2Ab in Australian populations of Helicoverpa punctigera (Lepidoptera: Noctuidae) from 2002 to 2006.

    PubMed

    Downes, S; Parker, T L; Mahon, R J

    2009-04-01

    Helicoverpa punctigera and Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) are important pests of field and horticultural crops in Australia. The former is endemic to the continent, whereas the latter is also distributed in Africa and Asia. Although H. armigera rapidly developed resistance to virtually every group of insecticide used against it, there is only one report of resistance to an insecticide in H. punctigera. In 1996 the Australian cotton industry adopted Ingard, which expresses the Bacillus thuringiensis (Bt) toxin gene cry1Ac. In 2004/2005, Bollgard II (which expresses Cry1Ac and Cry2Ab) replaced Ingard and has subsequently been grown on 80% of the area planted to cotton, Gossypium hirsutum L. From 2002/2003 to 2006/2007, F2 screens were used to detect resistance to Cry1Ac or Cry2Ab. We detected no alleles conferring resistance to Cry1Ac; the frequency was < 0.0005 (n = 2,180 alleles), with a 95% credibility interval between 0 and 0.0014. However, during the same period, we detected alleles that confer resistance to Cry2Ab at a frequency of 0.0018 (n = 2,192 alleles), with a 95% credibility interval between 0.0005 and 0.0040. For both toxins, the experiment-wise detection probability was 94%, i.e., if there actually was a resistance allele in any tested lines, we would have detected it 94% of the time. The first isolation of Cry2Ab resistance in H. punctigera was before the widespread deployment of Bollgard II. This finding supports our published notion for H. armigera that alleles conferring resistance to Cry2Ab may be present at detectable frequencies in populations before selection by transgenic crops.

  10. Intragenic allele pyramiding combines different specificities of wheat Pm3 resistance alleles.

    PubMed

    Brunner, Susanne; Hurni, Severine; Streckeisen, Philipp; Mayr, Gabriele; Albrecht, Mario; Yahiaoui, Nabila; Keller, Beat

    2010-11-01

    Some plant resistance genes occur as allelic series, with each member conferring specific resistance against a subset of pathogen races. In wheat, there are 17 alleles of the Pm3 gene. They encode nucleotide-binding (NB-ARC) and leucine-rich-repeat (LRR) domain proteins, which mediate resistance to distinct race spectra of powdery mildew. It is not known if specificities from different alleles can be combined to create resistance genes with broader specificity. Here, we used an approach based on avirulence analysis of pathogen populations to characterize the molecular basis of Pm3 recognition spectra. A large survey of mildew races for avirulence on the Pm3 alleles revealed that Pm3a has a resistance spectrum that completely contains that of Pm3f, but also extends towards additional races. The same is true for the Pm3b and Pm3c gene pair. The molecular analysis of these allelic pairs revealed a role of the NB-ARC protein domain in the efficiency of effector-dependent resistance. Analysis of the wild-type and chimeric Pm3 alleles identified single residues in the C-terminal LRR motifs as the main determinant of allele specificity. Variable residues of the N-terminal LRRs are necessary, but not sufficient, to confer resistance specificity. Based on these data, we constructed a chimeric Pm3 gene by intragenic allele pyramiding of Pm3d and Pm3e that showed the combined resistance specificity and, thus, a broader recognition spectrum compared with the parental alleles. Our findings support a model of stepwise evolution of Pm3 recognition specificities.

  11. Suppression among alleles encoding nucleotide-binding-leucine-rich repeat resistance proteins interferes with resistance in F1 hybrid and allele-pyramided wheat plants.

    PubMed

    Stirnweis, Daniel; Milani, Samira D; Brunner, Susanne; Herren, Gerhard; Buchmann, Gabriele; Peditto, David; Jordan, Tina; Keller, Beat

    2014-09-01

    The development of high-yielding varieties with broad-spectrum durable disease resistance is the ultimate goal of crop breeding. In plants, immune receptors of the nucleotide-binding-leucine-rich repeat (NB-LRR) class mediate race-specific resistance against pathogen attack. When employed in agriculture this type of resistance is often rapidly overcome by newly adapted pathogen races. The stacking of different resistance genes or alleles in F1 hybrids or in pyramided lines is a promising strategy for achieving more durable resistance. Here, we identify a molecular mechanism which can negatively interfere with the allele-pyramiding approach. We show that pairwise combinations of different alleles of the powdery mildew resistance gene Pm3 in F1 hybrids and stacked transgenic wheat lines can result in suppression of Pm3-based resistance. This effect is independent of the genetic background and solely dependent on the Pm3 alleles. Suppression occurs at the post-translational level, as levels of RNA and protein in the suppressed alleles are unaffected. Using a transient expression system in Nicotiana benthamiana, the LRR domain was identified as the domain conferring suppression. The results of this study suggest that the expression of closely related NB-LRR resistance genes or alleles in the same genotype can lead to dominant-negative interactions. These findings provide a molecular explanation for the frequently observed ineffectiveness of resistance genes introduced from the secondary gene pool into polyploid crop species and mark an important step in overcoming this limitation.

  12. Nucleotide variation and identification of novel blast resistance alleles of Pib by allele mining strategy.

    PubMed

    Ramkumar, G; Madhav, M S; Devi, S J S Rama; Prasad, M S; Babu, V Ravindra

    2015-04-01

    Pib is one of significant rice blast resistant genes, which provides resistance to wide range of isolates of rice blast pathogen, Magnaporthe oryzae. Identification and isolation of novel and beneficial alleles help in crop enhancement. Allele mining is one of the best strategies for dissecting the allelic variations at candidate gene and identification of novel alleles. Hence, in the present study, Pib was analyzed by allele mining strategy, and coding and non-coding (upstream and intron) regions were examined to identify novel Pib alleles. Allelic sequences comparison revealed that nucleotide polymorphisms at coding regions affected the amino acid sequences, while the polymorphism at upstream (non-coding) region affected the motifs arrangements. Pib alleles from resistant landraces, Sercher and Krengosa showed better resistance than Pib donor variety, might be due to acquired mutations, especially at LRR region. The evolutionary distance, Ka/Ks and phylogenetic analyzes also supported these results. Transcription factor binding motif analysis revealed that Pib (Sr) had a unique motif (DPBFCOREDCDC3), while five different motifs differentiated the resistance and susceptible Pib alleles. As the Pib is an inducible gene, the identified differential motifs helps to understand the Pib expression mechanism. The identified novel Pib resistant alleles, which showed high resistance to the rice blast, can be used directly in blast resistance breeding program as alternative Pib resistant sources.

  13. Identification of alleles conferring resistance to gray leaf spot in maize derived from its wild progenitor species teosinte (Zea mays ssp. parviglumis)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Gray Leaf Spot [(GLS), causal agent Cercospora zeae-maydis and Cercospora zeina] is an important maize disease in the United States. Current control methods for GLS include using resistant cultivars, crop rotation, chemical applications, and conventional tillage to reduce inoculum levels. Teosinte ...

  14. Identification of novel alleles of the rice blast resistance gene Pi54

    NASA Astrophysics Data System (ADS)

    Vasudevan, Kumar; Gruissem, Wilhelm; Bhullar, Navreet K.

    2015-10-01

    Rice blast is one of the most devastating rice diseases and continuous resistance breeding is required to control the disease. The rice blast resistance gene Pi54 initially identified in an Indian cultivar confers broad-spectrum resistance in India. We explored the allelic diversity of the Pi54 gene among 885 Indian rice genotypes that were found resistant in our screening against field mixture of naturally existing M. oryzae strains as well as against five unique strains. These genotypes are also annotated as rice blast resistant in the International Rice Genebank database. Sequence-based allele mining was used to amplify and clone the Pi54 allelic variants. Nine new alleles of Pi54 were identified based on the nucleotide sequence comparison to the Pi54 reference sequence as well as to already known Pi54 alleles. DNA sequence analysis of the newly identified Pi54 alleles revealed several single polymorphic sites, three double deletions and an eight base pair deletion. A SNP-rich region was found between a tyrosine kinase phosphorylation site and the nucleotide binding site (NBS) domain. Together, the newly identified Pi54 alleles expand the allelic series and are candidates for rice blast resistance breeding programs.

  15. Identification of novel alleles of the rice blast resistance gene Pi54.

    PubMed

    Vasudevan, Kumar; Gruissem, Wilhelm; Bhullar, Navreet K

    2015-10-26

    Rice blast is one of the most devastating rice diseases and continuous resistance breeding is required to control the disease. The rice blast resistance gene Pi54 initially identified in an Indian cultivar confers broad-spectrum resistance in India. We explored the allelic diversity of the Pi54 gene among 885 Indian rice genotypes that were found resistant in our screening against field mixture of naturally existing M. oryzae strains as well as against five unique strains. These genotypes are also annotated as rice blast resistant in the International Rice Genebank database. Sequence-based allele mining was used to amplify and clone the Pi54 allelic variants. Nine new alleles of Pi54 were identified based on the nucleotide sequence comparison to the Pi54 reference sequence as well as to already known Pi54 alleles. DNA sequence analysis of the newly identified Pi54 alleles revealed several single polymorphic sites, three double deletions and an eight base pair deletion. A SNP-rich region was found between a tyrosine kinase phosphorylation site and the nucleotide binding site (NBS) domain. Together, the newly identified Pi54 alleles expand the allelic series and are candidates for rice blast resistance breeding programs.

  16. Inheritance of Cry1F resistance, cross-resistance and frequency of resistant alleles in Spodoptera frugiperda (Lepidoptera: Noctuidae).

    PubMed

    Vélez, A M; Spencer, T A; Alves, A P; Moellenbeck, D; Meagher, R L; Chirakkal, H; Siegfried, B D

    2013-12-01

    Transgenic maize, Zea maize L., expressing the Cry1F protein from Bacillus thuringiensis has been registered for Spodoptera frugiperda (J. E. Smith) control since 2003. Unexpected damage to Cry1F maize was reported in 2006 in Puerto Rico and Cry1F resistance in S. frugiperda was documented. The inheritance of Cry1F resistance was characterized in a S. frugiperda resistant strain originating from Puerto Rico, which displayed >289-fold resistance to purified Cry1F. Concentration-response bioassays of reciprocal crosses of resistant and susceptible parental populations indicated that resistance is recessive and autosomal. Bioassays of the backcross of the F1 generation crossed with the resistant parental strain suggest that a single locus is responsible for resistance. In addition, cross-resistance to Cry1Aa, Cry1Ab, Cry1Ac, Cry1Ba, Cry2Aa and Vip3Aa was assessed in the Cry1F-resistant strain. There was no significant cross-resistance to Cry1Aa, Cry1Ba and Cry2Aa, although only limited effects were observed in the susceptible strain. Vip3Aa was highly effective against susceptible and resistant insects indicating no cross-resistance with Cry1F. In contrast, low levels of cross-resistance were observed for both Cry1Ab and Cry1Ac. Because the resistance is recessive and conferred by a single locus, an F1 screening assay was used to measure the frequency of Cry1F-resistant alleles from populations of Florida and Texas in 2010 and 2011. A total frequency of resistant alleles of 0.13 and 0.02 was found for Florida and Texas populations, respectively, indicating resistant alleles could be found in US populations, although there have been no reports of reduced efficacy of Cry1F-expressing plants.

  17. Resistance allele frequency to bt cotton in field populations of helicoverpa armigera (Lepidoptera: Noctuidae) in China.

    PubMed

    Liu, Fengyi; Xu, Zhiping; Chang, Juhua; Chen, Jin; Meng, Fengxia; Zhu, Yu Cheng; Shen, Jinliang

    2008-06-01

    Resistance evolution in target insects to Bacillus thurningiensis (Bt) cotton, Gossypium hirsutum L., is a main threat to Bt cotton technology. An increasing trend of population density of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) has been observed since 2001 in Qiuxian County (Hebei, China), where Bt cotton has been planted dominantly since 1998. This region was selected in 2006 and 2007 for estimating frequency of gene alleles conferring resistance to Bt cotton by screening the F1 progeny from single-pair cross between field-collected male and laboratory female of the Bt-resistant strain of H. armigera (F1 screen). F1 offspring from each single-pair line were screened for resistance alleles based on larval growth, development, and survival on Bt cotton leaves for 5 d. Two-year results indicated that approximately equal to 20% of field-collected males carried resistance alleles. The conservative estimate of the resistance allele frequency was 0.094 (95% CI, 0.044-0.145) for 2006 and 0.107 (95% CI, 0.055-0.159) for 2007. This is the first report of resistance allele frequency increase to such a high level in the field in China. Long-term adoption of Bt sprays, dominant planting of single-toxin-producing Bt cotton, and lack of conventional cotton refuge system might accelerate the resistance evolution in the region.

  18. Alarmingly High Segregation Frequencies of Quinolone Resistance Alleles within Human and Animal Microbiomes Are Not Explained by Direct Clinical Antibiotic Exposure

    PubMed Central

    Field, Wesley; Hershberg, Ruth

    2015-01-01

    Antibiotic resistance poses a major threat to human health. It is therefore important to characterize the frequency of resistance within natural bacterial environments. Many studies have focused on characterizing the frequencies with which horizontally acquired resistance genes segregate within natural bacterial populations. Yet, very little is currently understood regarding the frequency of segregation of resistance alleles occurring within the housekeeping targets of antibiotics. We surveyed a large number of metagenomic datasets extracted from a large variety of host-associated and non host-associated environments for such alleles conferring resistance to three groups of broad spectrum antibiotics: streptomycin, rifamycins, and quinolones. We find notable segregation frequencies of resistance alleles occurring within the target genes of each of the three antibiotics, with quinolone resistance alleles being the most frequent and rifamycin resistance alleles being the least frequent. Resistance allele frequencies varied greatly between different phyla and as a function of environment. The frequency of quinolone resistance alleles was especially high within host-associated environments, where it averaged an alarming ∼40%. Within host-associated environments, resistance to quinolones was most often conferred by a specific resistance allele. High frequencies of quinolone resistance alleles were also found within hosts that were not directly treated with antibiotics. Therefore, the high segregation frequency of quinolone resistance alleles occurring within the housekeeping targets of antibiotics in host-associated environments does not seem to be the sole result of clinical antibiotic usage. PMID:26019163

  19. Alarmingly High Segregation Frequencies of Quinolone Resistance Alleles within Human and Animal Microbiomes Are Not Explained by Direct Clinical Antibiotic Exposure.

    PubMed

    Field, Wesley; Hershberg, Ruth

    2015-05-26

    Antibiotic resistance poses a major threat to human health. It is therefore important to characterize the frequency of resistance within natural bacterial environments. Many studies have focused on characterizing the frequencies with which horizontally acquired resistance genes segregate within natural bacterial populations. Yet, very little is currently understood regarding the frequency of segregation of resistance alleles occurring within the housekeeping targets of antibiotics. We surveyed a large number of metagenomic datasets extracted from a large variety of host-associated and non host-associated environments for such alleles conferring resistance to three groups of broad spectrum antibiotics: streptomycin, rifamycins, and quinolones. We find notable segregation frequencies of resistance alleles occurring within the target genes of each of the three antibiotics, with quinolone resistance alleles being the most frequent and rifamycin resistance alleles being the least frequent. Resistance allele frequencies varied greatly between different phyla and as a function of environment. The frequency of quinolone resistance alleles was especially high within host-associated environments, where it averaged an alarming ∼ 40%. Within host-associated environments, resistance to quinolones was most often conferred by a specific resistance allele. High frequencies of quinolone resistance alleles were also found within hosts that were not directly treated with antibiotics. Therefore, the high segregation frequency of quinolone resistance alleles occurring within the housekeeping targets of antibiotics in host-associated environments does not seem to be the sole result of clinical antibiotic usage.

  20. Host mating system and the spread of a disease-resistant allele in a population

    USGS Publications Warehouse

    DeAngelis, D.L.; Koslow, Jennifer M.; Jiang, J.; Ruan, S.

    2008-01-01

    The model presented here modifies a susceptible-infected (SI) host-pathogen model to determine the influence of mating system on the outcome of a host-pathogen interaction. Both deterministic and stochastic (individual-based) versions of the model were used. This model considers the potential consequences of varying mating systems on the rate of spread of both the pathogen and resistance alleles within the population. We assumed that a single allele for disease resistance was sufficient to confer complete resistance in an individual, and that both homozygote and heterozygote resistant individuals had the same mean birth and death rates. When disease invaded a population with only an initial small fraction of resistant genes, inbreeding (selfing) tended to increase the probability that the disease would soon be eliminated from a small population rather than become endemic, while outcrossing greatly increased the probability that the population would become extinct due to the disease.

  1. Temperature Sensitivity Conferred by ligA Alleles from Psychrophilic Bacteria upon Substitution in Mesophilic Bacteria and a Yeast Species

    PubMed Central

    Pankowski, Jarosław A.; Puckett, Stephanie M.

    2016-01-01

    We have assembled a collection of 13 psychrophilic ligA alleles that can serve as genetic elements for engineering mesophiles to a temperature-sensitive (TS) phenotype. When these ligA alleles were substituted into Francisella novicida, they conferred a TS phenotype with restrictive temperatures between 33 and 39°C. When the F. novicida ligA hybrid strains were plated above their restrictive temperatures, eight of them generated temperature-resistant variants. For two alleles, the mutations that led to temperature resistance clustered near the 5′ end of the gene, and the mutations increased the predicted strength of the ribosome binding site at least 3-fold. Four F. novicida ligA hybrid strains generated no temperature-resistant variants at a detectable level. These results suggest that multiple mutations are needed to create temperature-resistant variants of these ligA gene products. One ligA allele was isolated from a Colwellia species that has a maximal growth temperature of 12°C, and this allele supported growth of F. novicida only as a hybrid between the psychrophilic and the F. novicida ligA genes. However, the full psychrophilic gene alone supported the growth of Salmonella enterica, imparting a restrictive temperature of 27°C. We also tested two ligA alleles from two Pseudoalteromonas strains for their ability to support the viability of a Saccharomyces cerevisiae strain that lacked its essential gene, CDC9, encoding an ATP-dependent DNA ligase. In both cases, the psychrophilic bacterial alleles supported yeast viability and their expression generated TS phenotypes. This collection of ligA alleles should be useful in engineering bacteria, and possibly eukaryotic microbes, to predictable TS phenotypes. PMID:26773080

  2. Rapid generation of drug-resistance alleles at endogenous loci using CRISPR-Cas9 indel mutagenesis

    PubMed Central

    Ipsaro, Jonathan J.; Shen, Chen; Arai, Eri; Xu, Yali; Kinney, Justin B.; Joshua-Tor, Leemor; Vakoc, Christopher R.

    2017-01-01

    Genetic alterations conferring resistance to the effects of chemical inhibitors are valuable tools for validating on-target effects in cells. Unfortunately, for many therapeutic targets such alleles are not available. To address this issue, we evaluated whether CRISPR-Cas9-mediated insertion/deletion (indel) mutagenesis can produce drug-resistance alleles at endogenous loci. This method takes advantage of the heterogeneous in-frame alleles produced following Cas9-mediated DNA cleavage, which we show can generate rare alleles that confer resistance to the growth-arrest caused by chemical inhibitors. We used this approach to identify novel resistance alleles of two lysine methyltransferases, DOT1L and EZH2, which are each essential for the growth of MLL-fusion leukemia cells. We biochemically characterized the DOT1L mutation, showing that it is significantly more active than the wild-type enzyme. These findings validate the on-target anti-leukemia activities of existing DOT1L and EZH2 inhibitors and reveal a simple method for deriving drug-resistance alleles for novel targets, which may have utility during early stages of drug development. PMID:28231254

  3. Rapid generation of drug-resistance alleles at endogenous loci using CRISPR-Cas9 indel mutagenesis.

    PubMed

    Ipsaro, Jonathan J; Shen, Chen; Arai, Eri; Xu, Yali; Kinney, Justin B; Joshua-Tor, Leemor; Vakoc, Christopher R; Shi, Junwei

    2017-01-01

    Genetic alterations conferring resistance to the effects of chemical inhibitors are valuable tools for validating on-target effects in cells. Unfortunately, for many therapeutic targets such alleles are not available. To address this issue, we evaluated whether CRISPR-Cas9-mediated insertion/deletion (indel) mutagenesis can produce drug-resistance alleles at endogenous loci. This method takes advantage of the heterogeneous in-frame alleles produced following Cas9-mediated DNA cleavage, which we show can generate rare alleles that confer resistance to the growth-arrest caused by chemical inhibitors. We used this approach to identify novel resistance alleles of two lysine methyltransferases, DOT1L and EZH2, which are each essential for the growth of MLL-fusion leukemia cells. We biochemically characterized the DOT1L mutation, showing that it is significantly more active than the wild-type enzyme. These findings validate the on-target anti-leukemia activities of existing DOT1L and EZH2 inhibitors and reveal a simple method for deriving drug-resistance alleles for novel targets, which may have utility during early stages of drug development.

  4. Geographically Distinct and Domain-Specific Sequence Variations in the Alleles of Rice Blast Resistance Gene Pib

    PubMed Central

    Vasudevan, Kumar; Vera Cruz, Casiana M.; Gruissem, Wilhelm; Bhullar, Navreet K.

    2016-01-01

    Rice blast is caused by Magnaporthe oryzae, which is the most destructive fungal pathogen affecting rice growing regions worldwide. The rice blast resistance gene Pib confers broad-spectrum resistance against Southeast Asian M. oryzae races. We investigated the allelic diversity of Pib in rice germplasm originating from 12 major rice growing countries. Twenty-five new Pib alleles were identified that have unique single nucleotide polymorphisms (SNPs), insertions and/or deletions, in addition to the polymorphic nucleotides that are shared between the different alleles. These partially or completely shared polymorphic nucleotides indicate frequent sequence exchange events between the Pib alleles. In some of the new Pib alleles, nucleotide diversity is high in the LRR domain, whereas, in others it is distributed among the NB-ARC and LRR domains. Most of the polymorphic amino acids in LRR and NB-ARC2 domains are predicted as solvent-exposed. Several of the alleles and the unique SNPs are country specific, suggesting a diversifying selection of alleles in various geographical locations in response to the locally prevalent M. oryzae population. Together, the new Pib alleles are an important genetic resource for rice blast resistance breeding programs and provide new information on rice-M. oryzae interactions at the molecular level. PMID:27446145

  5. Geographically Distinct and Domain-Specific Sequence Variations in the Alleles of Rice Blast Resistance Gene Pib.

    PubMed

    Vasudevan, Kumar; Vera Cruz, Casiana M; Gruissem, Wilhelm; Bhullar, Navreet K

    2016-01-01

    Rice blast is caused by Magnaporthe oryzae, which is the most destructive fungal pathogen affecting rice growing regions worldwide. The rice blast resistance gene Pib confers broad-spectrum resistance against Southeast Asian M. oryzae races. We investigated the allelic diversity of Pib in rice germplasm originating from 12 major rice growing countries. Twenty-five new Pib alleles were identified that have unique single nucleotide polymorphisms (SNPs), insertions and/or deletions, in addition to the polymorphic nucleotides that are shared between the different alleles. These partially or completely shared polymorphic nucleotides indicate frequent sequence exchange events between the Pib alleles. In some of the new Pib alleles, nucleotide diversity is high in the LRR domain, whereas, in others it is distributed among the NB-ARC and LRR domains. Most of the polymorphic amino acids in LRR and NB-ARC2 domains are predicted as solvent-exposed. Several of the alleles and the unique SNPs are country specific, suggesting a diversifying selection of alleles in various geographical locations in response to the locally prevalent M. oryzae population. Together, the new Pib alleles are an important genetic resource for rice blast resistance breeding programs and provide new information on rice-M. oryzae interactions at the molecular level.

  6. Natural variation in the Pto pathogen resistance gene within species of wild tomato (Lycopersicon). I. Functional analysis of Pto alleles.

    PubMed

    Rose, Laura E; Langley, Charles H; Bernal, Adriana J; Michelmore, Richard W

    2005-09-01

    Disease resistance to the bacterial pathogen Pseudomonas syringae pv. tomato (Pst) in the cultivated tomato, Lycopersicon esculentum, and the closely related L. pimpinellifolium is triggered by the physical interaction between plant disease resistance protein, Pto, and the pathogen avirulence protein, AvrPto. To investigate the extent to which variation in the Pto gene is responsible for naturally occurring variation in resistance to Pst, we determined the resistance phenotype of 51 accessions from seven species of Lycopersicon to isogenic strains of Pst differing in the presence of avrPto. One-third of the plants displayed resistance specifically when the pathogen expressed AvrPto, consistent with a gene-for-gene interaction. To test whether this resistance in these species was conferred specifically by the Pto gene, alleles of Pto were amplified and sequenced from 49 individuals and a subset (16) of these alleles was tested in planta using Agrobacterium-mediated transient assays. Eleven alleles conferred a hypersensitive resistance response (HR) in the presence of AvrPto, while 5 did not. Ten amino acid substitutions associated with the absence of AvrPto recognition and HR were identified, none of which had been identified in previous structure-function studies. Additionally, 3 alleles encoding putative pseudogenes of Pto were isolated from two species of Lycopersicon. Therefore, a large proportion, but not all, of the natural variation in the reaction to strains of Pst expressing AvrPto can be attributed to sequence variation in the Pto gene.

  7. Natural Variation in the Pto Pathogen Resistance Gene Within Species of Wild Tomato (Lycopersicon). I. Functional Analysis of Pto Alleles

    PubMed Central

    Rose, Laura E.; Langley, Charles H.; Bernal, Adriana J.; Michelmore, Richard W.

    2005-01-01

    Disease resistance to the bacterial pathogen Pseudomonas syringae pv. tomato (Pst) in the cultivated tomato, Lycopersicon esculentum, and the closely related L. pimpinellifolium is triggered by the physical interaction between plant disease resistance protein, Pto, and the pathogen avirulence protein, AvrPto. To investigate the extent to which variation in the Pto gene is responsible for naturally occurring variation in resistance to Pst, we determined the resistance phenotype of 51 accessions from seven species of Lycopersicon to isogenic strains of Pst differing in the presence of avrPto. One-third of the plants displayed resistance specifically when the pathogen expressed AvrPto, consistent with a gene-for-gene interaction. To test whether this resistance in these species was conferred specifically by the Pto gene, alleles of Pto were amplified and sequenced from 49 individuals and a subset (16) of these alleles was tested in planta using Agrobacterium-mediated transient assays. Eleven alleles conferred a hypersensitive resistance response (HR) in the presence of AvrPto, while 5 did not. Ten amino acid substitutions associated with the absence of AvrPto recognition and HR were identified, none of which had been identified in previous structure-function studies. Additionally, 3 alleles encoding putative pseudogenes of Pto were isolated from two species of Lycopersicon. Therefore, a large proportion, but not all, of the natural variation in the reaction to strains of Pst expressing AvrPto can be attributed to sequence variation in the Pto gene. PMID:15944360

  8. Genotyping of benzimidazole resistant and susceptible isolates of Haemonchus contortus from sheep by allele specific PCR.

    PubMed

    Mohanraj, Karthik; Subhadra, Subhra; Kalyanasundaram, Aravindan; Ilangopathy, Manikkavasagan; Raman, Muthusamy

    2017-03-01

    Extensive and indiscriminate use of the benzimidazole class of drugs has led to the onset of anthelmintic resistance. In tropical countries like India, Haemonchus contortus is the most pathogenic parasite infecting sheep and goats. The widespread presence of resistant helminths (especially H. contortus) threatens the livestock farming. The use of various drugs has led to single nucleotide polymorphism that causes specific amino acid substitutions in β-tubulin protein of H. contortus to confer resistance. This emphasizes the need for a survey on the present status of resistance in India. In this study, allele specific PCR was employed to screen the presence of a SNP, a thymine-to-adenine transversion which leads to substitution of amino acid in codon 200 of β-tubulin gene that is correlated specifically with BZ resistance. Third stage larvae (L3) from pooled faecal cultures of four organized sheep farms served as a source of genomic DNA for identification of H. contortus and further genotype analysis. A total of 1000 larvae was screened, out of which 673 larvae were identified as H. contortus. Among 673 H. contortus larvae, 539 larvae (80 %) were genotyped as homozygous resistant (rr) and remaining 134 (20 %) were heterozygous susceptible (Sr) by allele specific PCR. The concluded resistance status reasons out the failure of anthelmintic drug in treating ruminants. Immediate steps are needed to avoid further aggravation of the problem. Target selective treatment by reviewing the resistance status of individual drugs, appropriate use of anthelmintic drugs and other control strategies will provide a pragmatic option for delaying the further spread of anthelmintic resistance.

  9. Evaluating plague and smallpox as historical selective pressures for the CCR5-Delta 32 HIV-resistance allele.

    PubMed

    Galvani, Alison P; Slatkin, Montgomery

    2003-12-09

    The high frequency, recent origin, and geographic distribution of the CCR5-Delta 32 deletion allele together indicate that it has been intensely selected in Europe. Although the allele confers resistance against HIV-1, HIV has not existed in the human population long enough to account for this selective pressure. The prevailing hypothesis is that the selective rise of CCR5-Delta 32 to its current frequency can be attributed to bubonic plague. By using a population genetic framework that takes into account the temporal pattern and age-dependent nature of specific diseases, we find that smallpox is more consistent with this historical role.

  10. STV11 encodes a sulphotransferase and confers durable resistance to rice stripe virus.

    PubMed

    Wang, Qi; Liu, Yuqiang; He, Jun; Zheng, Xiaoming; Hu, Jinlong; Liu, Yanling; Dai, Huimin; Zhang, Yingxin; Wang, Baoxiang; Wu, Weixun; Gao, He; Zhang, Yunhui; Tao, Xiaorong; Deng, Huafeng; Yuan, Dingyang; Jiang, Ling; Zhang, Xin; Guo, Xiuping; Cheng, Xianian; Wu, Chuanyin; Wang, Haiyang; Yuan, Longping; Wan, Jianmin

    2014-09-09

    Rice stripe virus (RSV) causes one of the most serious viral diseases of rice (Oryza sativa L.), but the molecular basis of RSV resistance has remained elusive. Here we show that the resistant allele of rice STV11 (STV11-R) encodes a sulfotransferase (OsSOT1) catalysing the conversion of salicylic acid (SA) into sulphonated SA (SSA), whereas the gene product encoded by the susceptible allele STV11-S loses this activity. Sequence analyses suggest that the STV11-R and STV11-S alleles were predifferentiated in different geographic populations of wild rice, Oryza rufipogon, and remained prevalent in cultivated indica and japonica rice varieties, respectively. Introgression of the STV11-R allele into susceptible cultivars or heterologous transfer of STV11-R into tobacco plants confers effective resistance against RSV. Our results shed new insights into plant viral defense mechanisms and suggest effective means of breeding RSV-resistant crops using molecular marker-assisted selection or genetic engineering.

  11. Frequency of Cry1F Non-Recessive Resistance Alleles in North Carolina Field Populations of Spodoptera frugiperda (Lepidoptera: Noctuidae)

    PubMed Central

    Li, Guoping; Reisig, Dominic; Miao, Jin; Gould, Fred; Huang, Fangneng; Feng, Hongqiang

    2016-01-01

    Fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is a target species of transgenic corn (Zea mays L.) that expresses single and pyramided Bacillus thuringiensis (Bt) toxin. In 2014, S. frugiperda were collected from a light trap in North Carolina, and a total of 212 F1/F2 isofemale lines of S. frugiperda were screened for resistance to Bt and non-Bt corn. All of the 212 isolines were susceptible to corn tissue expressing Cry1A.105 + Cry2Ab, Cry1F + Cry1A.105 + Cry2Ab, and Cry1F + Cry1Ab + Vip3Aa20. Growth rate bioassays were performed to isolate non-recessive Bt resistance alleles. Seven individuals out of the 212 isofemale lines carried major non-recessive alleles conferring resistance to Cry1F. A pooled colony was created from the seven individuals. This colony was 151.21 times more resistant to Cry1F than a known-susceptible population and was also resistant to Cry1A.105, but was not resistant to Cry2Ab and Vip3Aa20. The results demonstrate that field populations of S. frugiperda collected from North Carolina are generally susceptible to Cry1F, but that some individuals carry resistant alleles. The data generated in this study can be used as baseline data for resistance monitoring. PMID:27119741

  12. Identification of Coupling and Repulsion Phase DNA Marker Associated With an Allele of a Gene Conferring Host Plant Resistance to Pigeonpea sterility mosaic virus (PPSMV) in Pigeonpea (Cajanus cajan L. Millsp.)

    PubMed Central

    Daspute, Abhijit; Fakrudin, B.

    2015-01-01

    Pigeonpea Sterility Mosaic Disease (PSMD) is an important foliar disease caused by Pigeonpea sterility mosaic virus (PPSMV) which is transmitted by eriophyid mites (Aceria cajani Channabasavanna). In present study, a F2 mapping population comprising 325 individuals was developed by crossing PSMD susceptible genotype (Gullyal white) and PSMD resistant genotype (BSMR 736). We identified a set of 32 out of 300 short decamer random DNA markers that showed polymorphism between Gullyal white and BSMR 736 parents. Among them, eleven DNA markers showed polymorphism including coupling and repulsion phase type of polymorphism across the parents. Bulked Segregant Analysis (BSA), revealed that the DNA marker, IABTPPN7, produced a single coupling phase marker (IABTPPN7414) and a repulsion phase marker (IABTPPN7983) co-segregating with PSMD reaction. Screening of 325 F2 population using IABTPPN7 revealed that the repulsion phase marker, IABTPPN7983, was co-segregating with the PSMD responsive SV1 at a distance of 23.9 cM for Bidar PPSMV isolate. On the other hand, the coupling phase marker IABTPPN7414 did not show any linkage with PSMD resistance. Additionally, single marker analysis both IABTPPN7983 (P<0.0001) and IABTPPN 7414 (P<0.0001) recorded a significant association with the PSMD resistance and explained a phenotypic variance of 31 and 36% respectively in F2 population. The repulsion phase marker, IABTPPN7983, could be of use in Marker-Assisted Selection (MAS) in the PPSMV resistance breeding programmes of pigeonpea. PMID:25774108

  13. Allele Mining Strategies: Principles and Utilisation for Blast Resistance Genes in Rice (Oryza sativa L.).

    PubMed

    Ashkani, Sadegh; Yusop, Mohd Rafii; Shabanimofrad, Mahmoodreza; Azady, Amin; Ghasemzadeh, Ali; Azizi, Parisa; Latif, Mohammad Abdul

    2015-01-01

    Allele mining is a promising way to dissect naturally occurring allelic variants of candidate genes with essential agronomic qualities. With the identification, isolation and characterisation of blast resistance genes in rice, it is now possible to dissect the actual allelic variants of these genes within an array of rice cultivars via allele mining. Multiple alleles from the complex locus serve as a reservoir of variation to generate functional genes. The routine sequence exchange is one of the main mechanisms of R gene evolution and development. Allele mining for resistance genes can be an important method to identify additional resistance alleles and new haplotypes along with the development of allele-specific markers for use in marker-assisted selection. Allele mining can be visualised as a vital link between effective utilisation of genetic and genomic resources in genomics-driven modern plant breeding. This review studies the actual concepts and potential of mining approaches for the discovery of alleles and their utilisation for blast resistance genes in rice. The details provided here will be important to provide the rice breeder with a worthwhile introduction to allele mining and its methodology for breakthrough discovery of fresh alleles hidden in hereditary diversity, which is vital for crop improvement.

  14. Multiple Avirulence Loci and Allele-Specific Effector Recognition Control the Pm3 Race-Specific Resistance of Wheat to Powdery Mildew[OPEN

    PubMed Central

    Roffler, Stefan; Stirnweis, Daniel; Treier, Georges; Herren, Gerhard; Korol, Abraham B.; Wicker, Thomas

    2015-01-01

    In cereals, several mildew resistance genes occur as large allelic series; for example, in wheat (Triticum aestivum and Triticum turgidum), 17 functional Pm3 alleles confer agronomically important race-specific resistance to powdery mildew (Blumeria graminis). The molecular basis of race specificity has been characterized in wheat, but little is known about the corresponding avirulence genes in powdery mildew. Here, we dissected the genetics of avirulence for six Pm3 alleles and found that three major Avr loci affect avirulence, with a common locus_1 involved in all AvrPm3-Pm3 interactions. We cloned the effector gene AvrPm3a2/f2 from locus_2, which is recognized by the Pm3a and Pm3f alleles. Induction of a Pm3 allele-dependent hypersensitive response in transient assays in Nicotiana benthamiana and in wheat demonstrated specificity. Gene expression analysis of Bcg1 (encoded by locus_1) and AvrPm3 a2/f2 revealed significant differences between isolates, indicating that in addition to protein polymorphisms, expression levels play a role in avirulence. We propose a model for race specificity involving three components: an allele-specific avirulence effector, a resistance gene allele, and a pathogen-encoded suppressor of avirulence. Thus, whereas a genetically simple allelic series controls specificity in the plant host, recognition on the pathogen side is more complex, allowing flexible evolutionary responses and adaptation to resistance genes. PMID:26452600

  15. A viable Arabidopsis pex13 missense allele confers severe peroxisomal defects and decreases PEX5 association with peroxisomes

    PubMed Central

    Woodward, Andrew W.; Fleming, Wendell A.; Burkhart, Sarah E.; Ratzel, Sarah E.; Bjornson, Marta; Bartel, Bonnie

    2014-01-01

    Peroxisomes are organelles that catabolize fatty acids and compartmentalize other oxidative metabolic processes in eukaryotes. Using a forward-genetic screen designed to recover severe peroxisome-defective mutants, we isolated a viable allele of the peroxisome biogenesis gene PEX13 with striking peroxisomal defects. The pex13-4 mutant requires an exogenous source of fixed carbon for pre-photosynthetic development and is resistant to the protoauxin indole-3-butyric acid. Delivery of peroxisome-targeted matrix proteins depends on the PEX5 receptor docking with PEX13 at the peroxisomal membrane, and we found severely reduced import of matrix proteins and less organelle-associated PEX5 in pex13-4 seedlings. Moreover, pex13-4 physiological and molecular defects were partially ameliorated when PEX5 was overexpressed, suggesting that PEX5 docking is partially compromised in this mutant and can be improved by increasing PEX5 levels. Because previously described Arabidopsis pex13 alleles either are lethal or confer only subtle defects, the pex13-4 mutant provides valuable insight into plant peroxisome receptor docking and matrix protein import. PMID:25008153

  16. Genetic basis for the hierarchical interaction between Tobamovirus spp. and L resistance gene alleles from different pepper species.

    PubMed

    Tomita, Reiko; Sekine, Ken-Taro; Mizumoto, Hiroyuki; Sakamoto, Masaru; Murai, Jun; Kiba, Akinori; Hikichi, Yasufumi; Suzuki, Kazumi; Kobayashi, Kappei

    2011-01-01

    The pepper L gene conditions the plant's resistance to Tobamovirus spp. Alleles L(1), L(2), L(3), and L(4) confer a broadening spectra of resistance to different virus pathotypes. In this study, we report the genetic basis for the hierarchical interaction between L genes and Tobamovirus pathotypes. We cloned L(3) using map-based methods, and L(1), L(1a), L(1c), L(2), L(2b), and L(4) using a homology-based method. L gene alleles encode coiled-coil, nucleotide-binding, leucine-rich repeat (LRR)-type resistance proteins with the ability to induce resistance response to the viral coat protein (CP) avirulence effectors by themselves. Their different recognition spectra in original pepper species were reproduced in an Agrobacterium tumefaciens-mediated transient expression system in Nicotiana benthamiana. Chimera analysis with L(1), which showed the narrowest recognition spectrum, indicates that the broader recognition spectra conferred by L(2), L(2b), L(3), and L(4) require different subregions of the LRR domain. We identified a critical amino acid residue for the determination of recognition spectra but other regions also influenced the L genes' resistance spectra. The results suggest that the hierarchical interactions between L genes and Tobamovirus spp. are determined by the interaction of multiple subregions of the LRR domain of L proteins with different viral CP themselves or some protein complexes including them.

  17. Insecticide Resistance Allele Frequencies in Anopheles gambiae before and after Anti-Vector Interventions in Continental Equatorial Guinea

    PubMed Central

    Reddy, Michael R.; Godoy, Adrian; Dion, Kirstin; Matias, Abrahan; Callender, Kevin; Kiszewski, Anthony E.; Kleinschmidt, Immo; Ridl, Frances C.; Powell, Jeffrey R.; Caccone, Adalgisa; Slotman, Michel A.

    2013-01-01

    Anti-malaria interventions that rely on insecticides can be compromised by insecticide-resistance alleles among malaria vectors. We examined frequency changes of resistance alleles at two loci, knockdown resistance (kdr) and acetylcholinesterase-1 (ace-1), which confer resistance to pyrethroids and DDT, and carbamates, respectively. A total of 7,059 Anopheles gambiae sensu stricto mosquitoes were analyzed from multiple sites across continental Equatorial Guinea. A subset of sites included samples collected pre-intervention (2007) and post-intervention (2009–2011). Both L1014S and L1014F resistance alleles were observed in almost all pre-intervention collections. In particular, L1014F was already at substantial frequencies in M form populations (17.6–74.6%), and at high frequencies (> 50%) in all but two S form populations. Comparison before and throughout anti-vector interventions showed drastic increases in L1014F, presumably caused by intensified selection pressure imposed by pyrethroids used in vector control efforts. In light of these findings, inclusion of other insecticide classes in any anti-vector intervention can be considered prudent. PMID:23438768

  18. Effective marker alleles associated with type 2 resistance to Fusarium head blight infection in fields

    PubMed Central

    Li, Tao; Luo, Meng; Zhang, Dadong; Wu, Di; Li, Lei; Bai, Guihua

    2016-01-01

    Molecular markers associated with known quantitative trait loci (QTLs) for type 2 resistance to Fusarium head blight (FHB) in bi-parental mapping population usually have more than two alleles in breeding populations. Therefore, understanding the association of each allele with FHB response is particularly important to marker-assisted enhancement of FHB resistance. In this paper, we evaluated FHB severities of 192 wheat accessions including landraces and commercial varieties in three field growing seasons, and genotyped this panel with 364 genome-wide informative molecular markers. Among them, 11 markers showed reproducible marker-trait association (p < 0.05) in at least two experiments using a mixed model. More than two alleles were identified per significant marker locus. These alleles were classified into favorable, unfavorable and neutral alleles according to the normalized genotypic values. The distributions of effective alleles at these loci in each wheat accession were characterized. Mean FHB severities increased with decreased number of favorable alleles at the reproducible loci. Chinese wheat landraces and Japanese accessions have more favorable alleles at the majority of the reproducible marker loci. FHB resistance levels of varieties can be greatly improved by introduction of these favorable alleles and removal of unfavorable alleles simultaneously at these QTL-linked marker loci. PMID:27436944

  19. Metabolic and target-site mechanisms combine to confer strong DDT resistance in Anopheles gambiae.

    PubMed

    Mitchell, Sara N; Rigden, Daniel J; Dowd, Andrew J; Lu, Fang; Wilding, Craig S; Weetman, David; Dadzie, Samuel; Jenkins, Adam M; Regna, Kimberly; Boko, Pelagie; Djogbenou, Luc; Muskavitch, Marc A T; Ranson, Hilary; Paine, Mark J I; Mayans, Olga; Donnelly, Martin J

    2014-01-01

    The development of resistance to insecticides has become a classic exemplar of evolution occurring within human time scales. In this study we demonstrate how resistance to DDT in the major African malaria vector Anopheles gambiae is a result of both target-site resistance mechanisms that have introgressed between incipient species (the M- and S-molecular forms) and allelic variants in a DDT-detoxifying enzyme. Sequencing of the detoxification enzyme, Gste2, from DDT resistant and susceptible strains of An. gambiae, revealed a non-synonymous polymorphism (I114T), proximal to the DDT binding domain, which segregated with strain phenotype. Recombinant protein expression and DDT metabolism analysis revealed that the proteins from the susceptible strain lost activity at higher DDT concentrations, characteristic of substrate inhibition. The effect of I114T on GSTE2 protein structure was explored through X-ray crystallography. The amino acid exchange in the DDT-resistant strain introduced a hydroxyl group nearby the hydrophobic DDT-binding region. The exchange does not result in structural alterations but is predicted to facilitate local dynamics and enzyme activity. Expression of both wild-type and 114T alleles the allele in Drosophila conferred an increase in DDT tolerance. The 114T mutation was significantly associated with DDT resistance in wild caught M-form populations and acts in concert with target-site mutations in the voltage gated sodium channel (Vgsc-1575Y and Vgsc-1014F) to confer extreme levels of DDT resistance in wild caught An. gambiae.

  20. Collagen I confers gamma radiation resistance.

    PubMed

    Azorin, E; González-Martínez, P R; Azorin, J

    2012-12-01

    The effect of collagen on the response of somatomammotroph tumor cells (GH3) to gamma, radiation therapy was studied in vitro. After incubating confluent GH3 cell monolayers in a serum-free, maintaining medium, either with or without collagen, the monolayers were irradiated with 137Cs, gamma radiation. Collagen reduces cell mortality via ERK1/2 activation, abolishing gamma radiation, cell death, and promotes cell invasion when acting in synergy with collagen and in association with the, MAPK/ERK1/2 signaling pathway activation. The presence of collagen in somatomammotroph tumors, confers resistance to radiation.

  1. Three cadherin alleles associated with resistance to Bacillus thuringiensis in pink bollworm

    PubMed Central

    Morin, Shai; Biggs, Robert W.; Sisterson, Mark S.; Shriver, Laura; Ellers-Kirk, Christa; Higginson, Dawn; Holley, Daniel; Gahan, Linda J.; Heckel, David G.; Carrière, Yves; Dennehy, Timothy J.; Brown, Judith K.; Tabashnik, Bruce E.

    2003-01-01

    Evolution of resistance by pests is the main threat to long-term insect control by transgenic crops that produce Bacillus thuringiensis (Bt) toxins. Because inheritance of resistance to the Bt toxins in transgenic crops is typically recessive, DNA-based screening for resistance alleles in heterozygotes is potentially much more efficient than detection of resistant homozygotes with bioassays. Such screening, however, requires knowledge of the resistance alleles in field populations of pests that are associated with survival on Bt crops. Here we report that field populations of pink bollworm (Pectinophora gossypiella), a major cotton pest, harbored three mutant alleles of a cadherin-encoding gene linked with resistance to Bt toxin Cry1Ac and survival on transgenic Bt cotton. Each of the three resistance alleles has a deletion expected to eliminate at least eight amino acids upstream of the putative toxin-binding region of the cadherin protein. Larvae with two resistance alleles in any combination were resistant, whereas those with one or none were susceptible to Cry1Ac. Together with previous evidence, the results reported here identify the cadherin gene as a leading target for DNA-based screening of resistance to Bt crops in lepidopteran pests. PMID:12695565

  2. One gene in diamondback moth confers resistance to four Bacillus thuringiensis toxins

    PubMed Central

    Tabashnik, Bruce E.; Liu, Yong-Biao; Finson, Naomi; Masson, Luke; Heckel, David G.

    1997-01-01

    Environmentally benign insecticides derived from the soil bacterium Bacillus thuringiensis (Bt) are the most widely used biopesticides, but their success will be short-lived if pests quickly adapt to them. The risk of evolution of resistance by pests has increased, because transgenic crops producing insecticidal proteins from Bt are being grown commercially. Efforts to delay resistance with two or more Bt toxins assume that independent mutations are required to counter each toxin. Moreover, it generally is assumed that resistance alleles are rare in susceptible populations. We tested these assumptions by conducting single-pair crosses with diamondback moth (Plutella xylostella), the first insect known to have evolved resistance to Bt in open field populations. An autosomal recessive gene conferred extremely high resistance to four Bt toxins (Cry1Aa, Cry1Ab, Cry1Ac, and Cry1F). The finding that 21% of the individuals from a susceptible strain were heterozygous for the multiple-toxin resistance gene implies that the resistance allele frequency was 10 times higher than the most widely cited estimate of the upper limit for the initial frequency of resistance alleles in susceptible populations. These findings suggest that pests may evolve resistance to some groups of toxins much faster than previously expected. PMID:9050831

  3. The wheat durable, multipathogen resistance gene Lr34 confers partial blast resistance in rice.

    PubMed

    Krattinger, Simon G; Sucher, Justine; Selter, Liselotte L; Chauhan, Harsh; Zhou, Bo; Tang, Mingzhi; Upadhyaya, Narayana M; Mieulet, Delphine; Guiderdoni, Emmanuel; Weidenbach, Denise; Schaffrath, Ulrich; Lagudah, Evans S; Keller, Beat

    2016-05-01

    The wheat gene Lr34 confers durable and partial field resistance against the obligate biotrophic, pathogenic rust fungi and powdery mildew in adult wheat plants. The resistant Lr34 allele evolved after wheat domestication through two gain-of-function mutations in an ATP-binding cassette transporter gene. An Lr34-like fungal disease resistance with a similar broad-spectrum specificity and durability has not been described in other cereals. Here, we transformed the resistant Lr34 allele into the japonica rice cultivar Nipponbare. Transgenic rice plants expressing Lr34 showed increased resistance against multiple isolates of the hemibiotrophic pathogen Magnaporthe oryzae, the causal agent of rice blast disease. Host cell invasion during the biotrophic growth phase of rice blast was delayed in Lr34-expressing rice plants, resulting in smaller necrotic lesions on leaves. Lines with Lr34 also developed a typical, senescence-based leaf tip necrosis (LTN) phenotype. Development of LTN during early seedling growth had a negative impact on formation of axillary shoots and spikelets in some transgenic lines. One transgenic line developed LTN only at adult plant stage which was correlated with lower Lr34 expression levels at seedling stage. This line showed normal tiller formation and more importantly, disease resistance in this particular line was not compromised. Interestingly, Lr34 in rice is effective against a hemibiotrophic pathogen with a lifestyle and infection strategy that is different from obligate biotrophic rusts and mildew fungi. Lr34 might therefore be used as a source in rice breeding to improve broad-spectrum disease resistance against the most devastating fungal disease of rice.

  4. A single amino acid change in acetolactate synthase confers resistance to valine in tobacco.

    PubMed

    Hervieu, F; Vaucheret, H

    1996-05-23

    The metabolic control of branches chain amino acid (BCAA) biosynthesis involves allosteric regulation of acetolactate synthase (ALS) by the end-products of the pathway, valine, leucine and isoleucine. We describe here the molecular basis of valine resistance. We cloned and sequenced an ALS gene from the tobacco mutant Valr-1 and found a single basepair substitution relative to the wild-type allele. This mutation causes a serine to leucine change in the amino acid sequence of ALS at position 214. We then mutagenized the wild-type allele of the ALS gene of Arabidopsis and found that it confers valine resistance when introduced into tobacco plants. Taken together, these results suggest that the serine to leucine change at position 214 of ALS is responsible for valine resistance in tobacco.

  5. Effects of antibiotic resistance alleles on bacterial evolutionary responses to viral parasites.

    PubMed

    Arias-Sánchez, Flor I; Hall, Alex R

    2016-05-01

    Antibiotic resistance has wide-ranging effects on bacterial phenotypes and evolution. However, the influence of antibiotic resistance on bacterial responses to parasitic viruses remains unclear, despite the ubiquity of such viruses in nature and current interest in therapeutic applications. We experimentally investigated this by exposing various Escherichia coli genotypes, including eight antibiotic-resistant genotypes and a mutator, to different viruses (lytic bacteriophages). Across 960 populations, we measured changes in population density and sensitivity to viruses, and tested whether variation among bacterial genotypes was explained by their relative growth in the absence of parasites, or mutation rate towards phage resistance measured by fluctuation tests for each phage. We found that antibiotic resistance had relatively weak effects on adaptation to phages, although some antibiotic-resistance alleles impeded the evolution of resistance to phages via growth costs. By contrast, a mutator allele, often found in antibiotic-resistant lineages in pathogenic populations, had a relatively large positive effect on phage-resistance evolution and population density under parasitism. This suggests costs of antibiotic resistance may modify the outcome of phage therapy against pathogenic populations previously exposed to antibiotics, but the effects of any co-occurring mutator alleles are likely to be stronger.

  6. The allelic relationship of genes giving resistance to mungbean yellow mosaic virus in blackgram.

    PubMed

    Verma, R P; Singh, D P

    1986-09-01

    The allelic relationship of resistance genes for MYMV was studied in blackgram (V. mungo (L.) Hepper). The resistant donors to MYMV - 'Pant U84' and 'UPU 2', and their F1, F2 and F3 generations - were inoculated artificially using an insect vector, whitefly (Bemisia tabaci Genn.). The two recessive genes previously reported for resistance were found to be the same in both donors.

  7. Disagreement in genotyping results of drug resistance alleles of the Plasmodium falciparum dihydrofolate reductase (Pfdhfr) gene by allele-specific PCR (ASPCR) assays and Sanger sequencing.

    PubMed

    Sharma, Divya; Lather, Manila; Dykes, Cherry L; Dang, Amita S; Adak, Tridibes; Singh, Om P

    2016-01-01

    The rapid spread of antimalarial drug resistance in Plasmodium falciparum over the past few decades has necessitated intensive monitoring of such resistance for an effective malaria control strategy. P. falciparum dihydropteroate synthase (Pfdhps) and P. falciparum dihydrofolate reductase (Pfdhfr) genes act as molecular markers for resistance against the antimalarial drugs sulphadoxine and pyrimethamine, respectively. Resistance to pyrimethamine which is used as a partner drug in artemisinin combination therapy (ACT) is associated with several mutations in the Pfdhfr gene, namely A16V, N51I, C59R, S108N/T and I164L. Therefore, routine monitoring of Pfdhfr-drug-resistant alleles in a population may help in effective drug resistance management. Allele-specific PCR (ASPCR) is one of the commonly used methods for molecular genotyping of these alleles. In this study, we genotyped 55 samples of P. falciparum for allele discrimination at four codons of Pfdhfr (N51, C59, S108 and I164) by ASPCR using published methods and by Sanger's DNA sequencing method. We found that the ASPCR identified a significantly higher number of mutant alleles as compared to the DNA sequencing method. Such discrepancies arise due to the non-specificity of some of the allele-specific primer sets and due to the lack of sensitivity of Sanger's DNA sequencing method to detect minor alleles present in multiple clone infections. This study reveals the need of a highly specific and sensitive method for genotyping and detecting minor drug-resistant alleles present in multiple clonal infections.

  8. A putative ABC transporter confers durable resistance to multiple fungal pathogens in wheat.

    PubMed

    Krattinger, Simon G; Lagudah, Evans S; Spielmeyer, Wolfgang; Singh, Ravi P; Huerta-Espino, Julio; McFadden, Helen; Bossolini, Eligio; Selter, Liselotte L; Keller, Beat

    2009-03-06

    Agricultural crops benefit from resistance to pathogens that endures over years and generations of both pest and crop. Durable disease resistance, which may be partial or complete, can be controlled by several genes. Some of the most devastating fungal pathogens in wheat are leaf rust, stripe rust, and powdery mildew. The wheat gene Lr34 has supported resistance to these pathogens for more than 50 years. Lr34 is now shared by wheat cultivars around the world. Here, we show that the LR34 protein resembles adenosine triphosphate-binding cassette transporters of the pleiotropic drug resistance subfamily. Alleles of Lr34 conferring resistance or susceptibility differ by three genetic polymorphisms. The Lr34 gene, which functions in the adult plant, stimulates senescence-like processes in the flag leaf tips and edges.

  9. Recombineering reveals a diverse collection of ribosomal proteins L4 and L22 that confer resistance to macrolide antibiotics

    PubMed Central

    Diner, Elie J.; Hayes, Christopher S.

    2009-01-01

    Summary Mutations in ribosomal proteins L4 and L22 confer resistance to erythromycin and other macrolide antibiotics in a variety of bacteria. L4 and L22 have elongated loops whose tips converge in the peptide exit tunnel near the macrolide binding site, and resistance mutations typically affect residues within these loops. Here, we use bacteriophage λ Red-mediated recombination, or “recombineering”, to uncover new L4 and L22 alleles that confer macrolide resistance in Escherichia coli. We randomized residues at the tips of the L4 and L22 loops using recombineered oligonucleotide libraries, and selected the mutagenized cells for erythromycin-resistant mutants. These experiments led to the identification of 341 different resistance mutations encoding 278 unique L4 and L22 proteins – the overwhelming majority of which are novel. Many resistance mutations were complex, involving multiple missense mutations, in-frame deletions, and insertions. Transfer of L4 and L22 mutations into wild-type cells by phage P1-mediated transduction demonstrated that each allele was sufficient to confer macrolide resistance. Although L4 and L22 mutants are typically resistant to most macrolides, selections carried out on different antibiotics revealed macrolide-specific resistance mutations. L22 Lys90Trp is one such allele, which confers resistance to erythromycin, but not tylosin or spiramycin. Purified L22 Lys90Trp ribosomes show reduced erythromycin binding, but have the same affinity for tylosin as wild-type ribosomes. Moreover, DMS methylation protection assays demonstrated that L22 Lys90Trp ribosomes bind tylosin more readily than erythromycin in vivo. This work underscores the exceptional functional plasticity of the L4 and L22 proteins, and highlights the utility of Red-mediated recombination in targeted genetic selections. PMID:19150357

  10. Monooxygenase Levels and Knockdown Resistance (kdr) Allele Frequencies in Anopheles gambiae and Anopheles arabiensis in Kenya

    PubMed Central

    Chen, Hong; Githeko, Andrew K; Githure, John I; Mutunga, James; Zhou, Guofa; Yan, Guiyun

    2013-01-01

    Pyrethroid-treated bed nets and indoor spray are important components of malaria control strategies in Kenya. Information on resistance to pyrethroid insecticides in Anopheles gambiae and An. arabiensis populations is essential to the selection of appropriate insecticides and the management of insecticide resistance. Monooxygenase activity and knockdown resistance (kdr) allele frequency are biochemical and molecular indicators of mosquito resistance to pyrethroids. This study determined baseline information on monooxygenase activity and kdr allele frequency in anopheline mosquitoes in the western region, the Great Rift Valley-central province region, and the coastal region of Kenya. A total of 1990 field-collected individuals, representing 12 An. gambiae and 22 An. arabiensis populations was analyzed. We found significant among-population variation in monooxygenase activity in An. gambiae and An. arabiensis and substantial variability among individuals within populations. Nine out of 12 An. gambiae populations exhibited significantly higher average monooxygenase activity than the susceptible Kisumu reference strain. The kdr alleles (L1014S) were detected in three An. gambiae populations, and one An. arabiensis population in western Kenya, but not in the Rift Valley-central region and the coastal Kenya region. All genotypes with the kdr alleles were heterozygous, and the conservative estimation of kdr allele frequency was below 1% in these four populations. Information on monooxygenase activity and kdr allele frequency reported in this study provided baseline data for monitoring insecticide resistance changes in Kenya during the era when large-scale insecticide-treated bednet and indoor residual spray campaigns were being implemented. PMID:18402140

  11. Non-recessive Bt toxin resistance conferred by an intracellular cadherin mutation in field-selected populations of cotton bollworm.

    PubMed

    Zhang, Haonan; Wu, Shuwen; Yang, Yihua; Tabashnik, Bruce E; Wu, Yidong

    2012-01-01

    Transgenic crops producing Bacillus thuringiensis (Bt) toxins have been planted widely to control insect pests, yet evolution of resistance by the pests can reduce the benefits of this approach. Recessive mutations in the extracellular domain of toxin-binding cadherin proteins that confer resistance to Bt toxin Cry1Ac by disrupting toxin binding have been reported previously in three major lepidopteran pests, including the cotton bollworm, Helicoverpa armigera. Here we report a novel allele from cotton bollworm with a deletion in the intracellular domain of cadherin that is genetically linked with non-recessive resistance to Cry1Ac. We discovered this allele in each of three field-selected populations we screened from northern China where Bt cotton producing Cry1Ac has been grown intensively. We expressed four types of cadherin alleles in heterologous cell cultures: susceptible, resistant with the intracellular domain mutation, and two complementary chimeric alleles with and without the mutation. Cells transfected with each of the four cadherin alleles bound Cry1Ac and were killed by Cry1Ac. However, relative to cells transfected with either the susceptible allele or the chimeric allele lacking the intracellular domain mutation, cells transfected with the resistant allele or the chimeric allele containing the intracellular domain mutation were less susceptible to Cry1Ac. These results suggest that the intracellular domain of cadherin is involved in post-binding events that affect toxicity of Cry1Ac. This evidence is consistent with the vital role of the intracellular region of cadherin proposed by the cell signaling model of the mode of action of Bt toxins. Considered together with previously reported data, the results suggest that both pore formation and cell signaling pathways contribute to the efficacy of Bt toxins.

  12. Three novel alleles of FLOURY ENDOSPERM2 (FLO2) confer dull grains with low amylose content in rice.

    PubMed

    Wu, Yong-pei; Pu, Chieh-han; Lin, Hung-ying; Huang, Hsin-ya; Huang, Ya-chen; Hong, Chwan-yang; Chang, Men-chi; Lin, Yann-rong

    2015-04-01

    Rice is a major food source for much of the world, and expanding our knowledge of genes conferring specific rice grain attributes will benefit both farmer and consumer. Here we present novel dull grain mutants with a low amylose content (AC) derived from mutagenesis of Oryza sativa, ssp. japonica cv. Taikeng 8 (TK8). Positional cloning of the gene conferring the dull grain phenotype revealed a point mutation located at the acceptor splice site of intron 11 of FLOURY ENDOSPERM2 (FLO2), encoding a tetratricopeptide repeat domain (TPR)-containing protein. Three novel flo2 alleles were identified herein, which surprisingly conferred dull rather than floury grains. The allelic diversity of flo2 perturbed the expression of starch synthesis-related genes including OsAGPL2, OsAGPS2b, OsGBSSI, OsBEI, OsBEIIb, OsISA1, and OsPUL. The effect of the flo2 mutations on the physicochemical properties of the grain included a low breakdown, setback, and consistency of rice, indicating a good elasticity and soft texture of cooked rice grains. The effects of FLO2, combined with the genetic background of the germplasm and environmental effects, resulted in a variety of different amylose content levels, grain appearance, and physicochemical properties of rice, providing a host of useful information to future grain-quality research and breeding.

  13. The GLO1 C332 (Ala111) allele confers autism vulnerability: family-based genetic association and functional correlates.

    PubMed

    Gabriele, Stefano; Lombardi, Federica; Sacco, Roberto; Napolioni, Valerio; Altieri, Laura; Tirindelli, Maria Cristina; Gregorj, Chiara; Bravaccio, Carmela; Rousseau, Francis; Persico, Antonio M

    2014-12-01

    Glyoxalase I (GLO1) is a homodimeric Zn(2+)-dependent isomerase involved in the detoxification of methylglyoxal and in limiting the formation of advanced glycation end-products (AGE). We previously found the rs4746 A332 (Glu111) allele of the GLO1 gene, which encodes for glyoxalase I, associated with "unaffected sibling" status in families with one or more children affected by Autism Spectrum Disorder (ASD). To identify and characterize this protective allele, we sequenced GLO1 exons and exon-intron junctions, detecting two additional SNPs (rs1049346, rs1130534) in linkage disequilibrium with rs4746. A family-based association study involving 385 simplex and 20 multiplex Italian families yielded a significant association with autism driven only by the rs4746 C332 (Ala111) allele itself (P < 0.05 and P < 0.001 under additive and dominant/recessive models, respectively). Glyoxalase enzymatic activity was significantly reduced both in leukocytes and in post-mortem temporocortical tissue (N = 38 and 13, respectively) of typically developing C332 allele carriers (P < 0.05 and <0.01), with no difference in Glo1 protein levels. Conversely, AGE amounts were significantly higher in the same C332 post-mortem brains (P = 0.001), with a strong negative correlation between glyoxalase activity and AGE levels (τ = -0.588, P < 0.01). Instead, 19 autistic brains show a dysregulation of the glyoxalase-AGE axis (τ = -0.209, P = 0.260), with significant blunting of glyoxalase activity and AGE amounts compared to controls (P < 0.05), and loss of rs4746 genotype effects. In summary, the GLO1 C332 (Ala111) allele confers autism vulnerability by reducing brain glyoxalase activity and enhancing AGE formation, but years after an autism diagnosis the glyoxalase-AGE axis appears profoundly disrupted, with loss of C332 allelic effects.

  14. Allelic Variation on Murine Chromosome 11 Modifies Host Inflammatory Responses and Resistance to Bacillus anthracis

    DTIC Science & Technology

    2011-12-01

    Allelic Variation on Murine Chromosome 11 Modifies Host Inflammatory Responses and Resistance to Bacillus anthracis Jill K. Terra1, Bryan France1...of America Abstract Anthrax is a potentially fatal disease resulting from infection with Bacillus anthracis. The outcome of infection is influenced by...Inflammatory Responses and Resistance to Bacillus anthracis. PLoS Pathog 7(12): e1002469. doi:10.1371/journal.ppat.1002469 Editor: Theresa M. Koehler, The

  15. BCR-ABL1 compound mutations combining key kinase domain positions confer clinical resistance to ponatinib in Ph chromosome-positive leukemia.

    PubMed

    Zabriskie, Matthew S; Eide, Christopher A; Tantravahi, Srinivas K; Vellore, Nadeem A; Estrada, Johanna; Nicolini, Franck E; Khoury, Hanna J; Larson, Richard A; Konopleva, Marina; Cortes, Jorge E; Kantarjian, Hagop; Jabbour, Elias J; Kornblau, Steven M; Lipton, Jeffrey H; Rea, Delphine; Stenke, Leif; Barbany, Gisela; Lange, Thoralf; Hernández-Boluda, Juan-Carlos; Ossenkoppele, Gert J; Press, Richard D; Chuah, Charles; Goldberg, Stuart L; Wetzler, Meir; Mahon, Francois-Xavier; Etienne, Gabriel; Baccarani, Michele; Soverini, Simona; Rosti, Gianantonio; Rousselot, Philippe; Friedman, Ran; Deininger, Marie; Reynolds, Kimberly R; Heaton, William L; Eiring, Anna M; Pomicter, Anthony D; Khorashad, Jamshid S; Kelley, Todd W; Baron, Riccardo; Druker, Brian J; Deininger, Michael W; O'Hare, Thomas

    2014-09-08

    Ponatinib is the only currently approved tyrosine kinase inhibitor (TKI) that suppresses all BCR-ABL1 single mutants in Philadelphia chromosome-positive (Ph(+)) leukemia, including the recalcitrant BCR-ABL1(T315I) mutant. However, emergence of compound mutations in a BCR-ABL1 allele may confer ponatinib resistance. We found that clinically reported BCR-ABL1 compound mutants center on 12 key positions and confer varying resistance to imatinib, nilotinib, dasatinib, ponatinib, rebastinib, and bosutinib. T315I-inclusive compound mutants confer high-level resistance to TKIs, including ponatinib. In vitro resistance profiling was predictive of treatment outcomes in Ph(+) leukemia patients. Structural explanations for compound mutation-based resistance were obtained through molecular dynamics simulations. Our findings demonstrate that BCR-ABL1 compound mutants confer different levels of TKI resistance, necessitating rational treatment selection to optimize clinical outcome.

  16. Simultaneous editing of three homoeoalleles in hexaploid bread wheat confers heritable resistance to powdery mildew.

    PubMed

    Wang, Yanpeng; Cheng, Xi; Shan, Qiwei; Zhang, Yi; Liu, Jinxing; Gao, Caixia; Qiu, Jin-Long

    2014-09-01

    Sequence-specific nucleases have been applied to engineer targeted modifications in polyploid genomes, but simultaneous modification of multiple homoeoalleles has not been reported. Here we use transcription activator-like effector nuclease (TALEN) and clustered, regularly interspaced, short palindromic repeats (CRISPR)-Cas9 (refs. 4,5) technologies in hexaploid bread wheat to introduce targeted mutations in the three homoeoalleles that encode MILDEW-RESISTANCE LOCUS (MLO) proteins. Genetic redundancy has prevented evaluation of whether mutation of all three MLO alleles in bread wheat might confer resistance to powdery mildew, a trait not found in natural populations. We show that TALEN-induced mutation of all three TaMLO homoeologs in the same plant confers heritable broad-spectrum resistance to powdery mildew. We further use CRISPR-Cas9 technology to generate transgenic wheat plants that carry mutations in the TaMLO-A1 allele. We also demonstrate the feasibility of engineering targeted DNA insertion in bread wheat through nonhomologous end joining of the double-strand breaks caused by TALENs. Our findings provide a methodological framework to improve polyploid crops.

  17. Vip3A Resistance Alleles Exist at High Levels in Australian Targets before Release of Cotton Expressing This Toxin

    PubMed Central

    Mahon, Rod J.; Downes, Sharon J.; James, Bill

    2012-01-01

    Crops engineered to produce insecticidal crystal (Cry) proteins from the soil bacterium Bacillus thuringiensis (Bt) have revolutionised pest control in agriculture. However field-level resistance to Bt has developed in some targets. Utilising novel vegetative insecticidal proteins (Vips), also derived from Bt but genetically distinct from Cry toxins, is a possible solution that biotechnical companies intend to employ. Using data collected over two seasons we determined that, before deployment of Vip-expressing plants in Australia, resistance alleles exist in key targets as polymorphisms at frequencies of 0.027 (n = 273 lines, 95% CI = 0.019–0.038) in H. armigera and 0.008 (n = 248 lines, 0.004–0.015) in H. punctigera. These frequencies are above mutation rates normally encountered. Homozygous resistant neonates survived doses of Vip3A higher than those estimated in field-grown plants. Fortunately the resistance is largely, if not completely, recessive and does not confer resistance to the Bt toxins Cry1Ac or Cry2Ab already deployed in cotton crops. These later characteristics are favourable for resistance management; however the robustness of Vip3A inclusive varieties will depend on resistance frequencies to the Cry toxins when it is released (anticipated 2016) and the efficacy of Vip3A throughout the season. It is appropriate to pre-emptively screen key targets of Bt crops elsewhere, especially those such as H. zea in the USA, which is not only closely related to H. armigera but also will be exposed to Vip in several varieties of cotton and corn. PMID:22761737

  18. Vip3A resistance alleles exist at high levels in Australian targets before release of cotton expressing this toxin.

    PubMed

    Mahon, Rod J; Downes, Sharon J; James, Bill

    2012-01-01

    Crops engineered to produce insecticidal crystal (Cry) proteins from the soil bacterium Bacillus thuringiensis (Bt) have revolutionised pest control in agriculture. However field-level resistance to Bt has developed in some targets. Utilising novel vegetative insecticidal proteins (Vips), also derived from Bt but genetically distinct from Cry toxins, is a possible solution that biotechnical companies intend to employ. Using data collected over two seasons we determined that, before deployment of Vip-expressing plants in Australia, resistance alleles exist in key targets as polymorphisms at frequencies of 0.027 (n = 273 lines, 95% CI = 0.019-0.038) in H. armigera and 0.008 (n = 248 lines, 0.004-0.015) in H. punctigera. These frequencies are above mutation rates normally encountered. Homozygous resistant neonates survived doses of Vip3A higher than those estimated in field-grown plants. Fortunately the resistance is largely, if not completely, recessive and does not confer resistance to the Bt toxins Cry1Ac or Cry2Ab already deployed in cotton crops. These later characteristics are favourable for resistance management; however the robustness of Vip3A inclusive varieties will depend on resistance frequencies to the Cry toxins when it is released (anticipated 2016) and the efficacy of Vip3A throughout the season. It is appropriate to pre-emptively screen key targets of Bt crops elsewhere, especially those such as H. zea in the USA, which is not only closely related to H. armigera but also will be exposed to Vip in several varieties of cotton and corn.

  19. Selection and spread of artemisinin-resistant alleles in Thailand prior to the global artemisinin resistance containment campaign.

    PubMed

    Talundzic, Eldin; Okoth, Sheila Akinyi; Congpuong, Kanungnit; Plucinski, Mateusz M; Morton, Lindsay; Goldman, Ira F; Kachur, Patrick S; Wongsrichanalai, Chansuda; Satimai, Wichai; Barnwell, John W; Udhayakumar, Venkatachalam

    2015-04-01

    The recent emergence of artemisinin resistance in the Greater Mekong Subregion poses a major threat to the global effort to control malaria. Tracking the spread and evolution of artemisinin-resistant parasites is critical in aiding efforts to contain the spread of resistance. A total of 417 patient samples from the year 2007, collected during malaria surveillance studies across ten provinces in Thailand, were genotyped for the candidate Plasmodium falciparum molecular marker of artemisinin resistance K13. Parasite genotypes were examined for K13 propeller mutations associated with artemisinin resistance, signatures of positive selection, and for evidence of whether artemisinin-resistant alleles arose independently across Thailand. A total of seven K13 mutant alleles were found (N458Y, R539T, E556D, P574L, R575K, C580Y, S621F). Notably, the R575K and S621F mutations have previously not been reported in Thailand. The most prevalent artemisinin resistance-associated K13 mutation, C580Y, carried two distinct haplotype profiles that were separated based on geography, along the Thai-Cambodia and Thai-Myanmar borders. It appears these two haplotypes may have independent evolutionary origins. In summary, parasites with K13 propeller mutations associated with artemisinin resistance were widely present along the Thai-Cambodia and Thai-Myanmar borders prior to the implementation of the artemisinin resistance containment project in the region.

  20. Mapping Rph20: a gene conferring adult plant resistance to Puccinia hordei in barley.

    PubMed

    Hickey, L T; Lawson, W; Platz, G J; Dieters, M; Arief, V N; Germán, S; Fletcher, S; Park, R F; Singh, D; Pereyra, S; Franckowiak, J

    2011-06-01

    A doubled haploid (DH) barley (Hordeum vulgare L.) population of 334 lines (ND24260 × Flagship) genotyped with DArT markers was used to map genes for adult plant resistance (APR) to leaf rust (Puccinia hordei Otth) under field conditions in Australia and Uruguay. The Australian barley cultivar Flagship carries an APR gene (qRphFlag) derived from the cultivar Vada. Association analysis and composite interval mapping identified two genes conferring APR in this DH population. qRphFlag was mapped to the short arm of chromosome 5H (5HS), accounting for 64-85% of the phenotypic variation across four field environments and 56% under controlled environmental conditions (CEC). A second quantitative trait locus (QTL) from ND24260 (qRphND) with smaller effect was mapped to chromosome 6HL. In the absence of qRphFlag, qRphND conferred only a low level of resistance. DH lines displaying the highest level of APR carried both genes. Sequence information for the critical DArT marker bPb-0837 (positioned at 21.2 cM on chromosome 5HS) was used to develop bPb-0837-PCR, a simple PCR-based marker for qRphFlag. The 245 bp fragment for bPb-0837-PCR was detected in a range of barley cultivars known to possess APR, which was consistent with previous tests of allelism, demonstrating that the qRphFlag resistant allele is common in leaf rust resistant cultivars derived from Vada and Emir. qRphFlag has been designated Rph20, the first gene conferring APR to P. hordei to be characterised in barley. The PCR marker will likely be effective in marker-assisted selection for Rph20.

  1. A codon deletion confers resistance to herbicides inhibiting protoporphyrinogen oxidase

    PubMed Central

    Patzoldt, William L.; Hager, Aaron G.; McCormick, Joel S.; Tranel, Patrick J.

    2006-01-01

    Herbicides that act by inhibiting protoporphyrinogen oxidase (PPO) are widely used to control weeds in a variety of crops. The first weed to evolve resistance to PPO-inhibiting herbicides was Amaranthus tuberculatus, a problematic weed in the midwestern United States that previously had evolved multiple resistances to herbicides inhibiting two other target sites. Evaluation of a PPO-inhibitor-resistant A. tuberculatus biotype revealed that resistance was a (incompletely) dominant trait conferred by a single, nuclear gene. Three genes predicted to encode PPO were identified in A. tuberculatus. One gene from the resistant biotype, designated PPX2L, contained a codon deletion that was shown to confer resistance by complementation of a hemG mutant strain of Escherichia coli grown in the presence and absence of the PPO inhibitor lactofen. PPX2L is predicted to encode both plastid- and mitochondria-targeted PPO isoforms, allowing a mutation in a single gene to confer resistance to two herbicide target sites. Unique aspects of the resistance mechanism include an amino acid deletion, rather than a substitution, and the dual-targeting nature of the gene, which may explain why resistance to PPO inhibitors has been rare. PMID:16894159

  2. A codon deletion confers resistance to herbicides inhibiting protoporphyrinogen oxidase.

    PubMed

    Patzoldt, William L; Hager, Aaron G; McCormick, Joel S; Tranel, Patrick J

    2006-08-15

    Herbicides that act by inhibiting protoporphyrinogen oxidase (PPO) are widely used to control weeds in a variety of crops. The first weed to evolve resistance to PPO-inhibiting herbicides was Amaranthus tuberculatus, a problematic weed in the midwestern United States that previously had evolved multiple resistances to herbicides inhibiting two other target sites. Evaluation of a PPO-inhibitor-resistant A. tuberculatus biotype revealed that resistance was a (incompletely) dominant trait conferred by a single, nuclear gene. Three genes predicted to encode PPO were identified in A. tuberculatus. One gene from the resistant biotype, designated PPX2L, contained a codon deletion that was shown to confer resistance by complementation of a hemG mutant strain of Escherichia coli grown in the presence and absence of the PPO inhibitor lactofen. PPX2L is predicted to encode both plastid- and mitochondria-targeted PPO isoforms, allowing a mutation in a single gene to confer resistance to two herbicide target sites. Unique aspects of the resistance mechanism include an amino acid deletion, rather than a substitution, and the dual-targeting nature of the gene, which may explain why resistance to PPO inhibitors has been rare.

  3. Alleles conferring improved fiber quality from EMS mutagenesis of elite cotton genotypes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The elite gene pool of cotton (Gossypium spp.) has less diversity than those of most other major crops, making identification of novel alleles important to ongoing crop improvement. A total of 3,164 M5 lines resulting from ethyl methanesulfonate mutagenesis of two G. hirsutum breeding lines, TAM 94L...

  4. Dual Cry2Ab and Vip3A resistant strains of Helicoverpa armigera and Helicoverpa punctigera (Lepidoptera: Noctuidae); testing linkage between loci and monitoring of allele frequencies.

    PubMed

    Walsh, T K; Downes, S J; Gascoyne, J; James, W; Parker, T; Armstrong, J; Mahon, R J

    2014-08-01

    Considerable attention has been given to delaying the evolution of insect resistance to toxins produced by transgenic crops. The major pests of cotton in Australia are the Lepidoptera Helicoverpa armigera (Hubner, 1805) and Helicoverpa punctigera (Wallengren), and the toxins deployed in current and imminent transgenic cotton varieties are Cry1Ac, Cry2Ab and Vip3A from Bacillus thuringiensis. In this study, lines that carry alleles conferring resistance to Cry2Ab and Vip3A were isolated using F2 tests. Extensive work on the Cry2Ab resistant lines, and preliminary work on the Vip3A resistant lines, suggested a single common resistance to each toxin in both species thereby justifying the use of more efficient F1 tests as the primary means for monitoring changes over time. A potential further efficiency could be gained by developing a single resistant line that carries both types of Bt resistance. Herein we report on work with both H. armigera and H. punctigera that tests whether dual Cry2Ab-Vip3A resistant lines can be developed and, if so, whether they can be used to effectively monitor resistance frequencies. Furthermore, the creation of dual resistant lines allowed linkage between the Cry2Ab and Vip3A resistances to be investigated for H. punctigera. We show that dual resistant lines can be used to increase the efficiency of the F1 screen for recessive alleles, and that in H. punctigera there is no linkage between Cry2Ab and Vip3A resistance.

  5. Selection of Heterodera glycines chorismate mutase-1 alleles on nematode-resistant soybean.

    PubMed

    Lambert, Kris N; Bekal, Sadia; Domier, Leslie L; Niblack, Terry L; Noel, Gregory R; Smyth, Charles A

    2005-06-01

    The soybean cyst nematode Heterodera glycines is the most destructive pathogen of soybean in the Unites States. Diversity in the parasitic ability of the nematode allows it to reproduce on nematode-resistant soybean. H. glycines chorismate mutase-1 (Hg-CM-1) is a nematode enzyme with the potential to suppress host plant defense compounds; therefore, it has the potential to enhance the parasitic ability of nematodes expressing the gene. Hg-cm-1 is a member of a gene family where two alleles, Hg-cm-1A and Hg-cm-1B, have been identified. Analysis of the Hg-cm-1 gene copy number revealed that there are multiple copies of Hg-cm-1 alleles in the H. glycines genome. H. glycines inbred lines were crossed to ultimately generate three F2 populations of second-stage juveniles (J2s) segregating for Hg-cm-1A and Hg-cm-1B. Segregation of Hg-cm-1A and 1B approximated a 1:2:1 ratio, which suggested that Hg-cm-1 is organized in a cluster of genes that segregate roughly as a single locus. The F2 H. glycines J2 populations were used to infect nematode-resistant (Hartwig, PI88788, and PI90763) and susceptible (Lee 74) soybean plants. H. glycines grown on Hartwig, Lee 74, and PI90763 showed allelic frequencies similar to Hg-cm-1A/B, but nematodes grown on PI88788 contained predominately Hg-cm-1A allele as a result of a statistically significant drop of Hg-cm-1B in the population. This result suggests that specific Hg-cm-1 alleles, or a closely linked gene, may aid H. glycines in adapting to particular soybean hosts.

  6. Transcriptome and allele specificity associated with a 3BL locus for Fusarium crown rot resistance in bread wheat.

    PubMed

    Ma, Jian; Stiller, Jiri; Zhao, Qiang; Feng, Qi; Cavanagh, Colin; Wang, Penghao; Gardiner, Donald; Choulet, Frédéric; Feuillet, Catherine; Zheng, You-Liang; Wei, Yuming; Yan, Guijun; Han, Bin; Manners, John M; Liu, Chunji

    2014-01-01

    Fusarium pathogens cause two major diseases in cereals, Fusarium crown rot (FCR) and head blight (FHB). A large-effect locus conferring resistance to FCR disease was previously located to chromosome arm 3BL (designated as Qcrs-3B) and several independent sets of near isogenic lines (NILs) have been developed for this locus. In this study, five sets of the NILs were used to examine transcriptional changes associated with the Qcrs-3B locus and to identify genes linked to the resistance locus as a step towards the isolation of the causative gene(s). Of the differentially expressed genes (DEGs) detected between the NILs, 12.7% was located on the single chromosome 3B. Of the expressed genes containing SNP (SNP-EGs) detected, 23.5% was mapped to this chromosome. Several of the DEGs and SNP-EGs are known to be involved in host-pathogen interactions, and a large number of the DEGs were among those detected for FHB in previous studies. Of the DEGs detected, 22 were mapped in the Qcrs-3B interval and they included eight which were detected in the resistant isolines only. The enrichment of DEG, and not necessarily those containing SNPs between the resistant and susceptible isolines, around the Qcrs-3B locus is suggestive of local regulation of this region by the resistance allele. Functions for 13 of these DEGs are known. Of the SNP-EGs, 28 were mapped in the Qcrs-3B interval and biological functions for 16 of them are known. These results provide insights into responses regulated by the 3BL locus and identify a tractable number of target genes for fine mapping and functional testing to identify the causative gene(s) at this QTL.

  7. Detection of bovine leukocyte antigen DRB3 alleles as candidate markers for clinical mastitis resistance in Holstein x Zebu.

    PubMed

    Duangjinda, M; Buayai, D; Pattarajinda, V; Phasuk, Y; Katawatin, S; Vongpralub, T; Chaiyotvittayakul, A

    2009-02-01

    Bovine leukocyte antigen DRB3 alleles from Holstein x Zebu crossbred dairy cows (n = 409) were analyzed using the PCR-RFLP technique. Exon II of DRB3 was amplified using locus-specific primers (HLO30/HLO32), followed by digestion with 3 restriction enzymes (RsaI, BstyI, and HaeIII). Forty alleles were found with frequency ranging from 0.005 to 0.139. The most frequently detected alleles of Holstein x Zebu were DRB3*16, *51, *23, *11, *8, and *1, accounting for 61.12% of the alleles in the population. Detection of candidate alleles for clinical mastitis occurrence was performed by logistic regression. It was found that percentage of Holstein fraction in crossbred cows had a nonsignificant effect (P > 0.05). However, parity had a significant effect on mastitis occurrence. In addition, DRB3*1 and *52 were the most associated with the occurrence of clinical mastitis, whereas *15, *51, and *22 were associated with resistance in crossbred populations. This is the first report of association of DRB3*15 and *51 with mastitis resistance. The association was validated by examining the candidate alleles in another commercial population. Highly susceptible (n = 43) and resistant (n = 42) groups of Holstein x Zebu cows were investigated. The result confirmed that DRB3*1 and *52 could be considered as susceptibility alleles, whereas *15, *51, and *22 could be considered as resistant alleles in Holstein x Zebu raised under tropical conditions. In addition, allele effects on 305-d milk production were estimated by BLUP. It was shown that most alleles associated with high clinical mastitis occurrence were related to increased milk yield. This study revealed that allele DRB3*10 had the greatest effect on increasing milk yield with moderate resistance to clinical mastitis, which could be used as a potential marker for selection in dairy genetic evaluation.

  8. Effective marker alleles associated with type II resistance of wheat to Fusarium head blight infection in fields

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Molecular markers associated with known quantitative trait loci (QTLs) for type 2 resistance to Fusarium head blight (FHB) in bi-parental mapping populations usually have more than two alleles in breeding populations. Therefore, understanding the association of each allele with FHB response is parti...

  9. Fitness cost of chromosomal drug resistance-conferring mutations.

    PubMed

    Sander, Peter; Springer, Burkhard; Prammananan, Therdsak; Sturmfels, Antje; Kappler, Martin; Pletschette, Michel; Böttger, Erik C

    2002-05-01

    To study the cost of chromosomal drug resistance mutations to bacteria, we investigated the fitness cost of mutations that confer resistance to different classes of antibiotics affecting bacterial protein synthesis (aminocyclitols, 2-deoxystreptamines, macrolides). We used a model system based on an in vitro competition assay with defined Mycobacterium smegmatis laboratory mutants; selected mutations were introduced by genetic techniques to address the possibility that compensatory mutations ameliorate the resistance cost. We found that the chromosomal drug resistance mutations studied often had only a small fitness cost; compensatory mutations were not involved in low-cost or no-cost resistance mutations. When drug resistance mutations found in clinical isolates were considered, selection of those mutations that have little or no fitness cost in the in vitro competition assay seems to occur. These results argue against expectations that link decreased levels of antibiotic consumption with the decline in the level of resistance.

  10. The apolipoprotein epsilon4 allele confers additional risk in children with familial hypercholesterolemia.

    PubMed

    Wiegman, Albert; Sijbrands, Eric J G; Rodenburg, Jessica; Defesche, Joep C; de Jongh, Saskia; Bakker, Henk D; Kastelein, John J P

    2003-06-01

    Children with familial hypercholesterolemia (FH) exhibit substantial variance of LDL cholesterol. In previous studies, family members of children with FH were included, which may have influenced results. To avoid such bias, we studied phenotype in 450 unrelated children with FH and in 154 affected sib-pairs. In known families with classical FH, diagnosis was based on plasma LDL cholesterol above the age- and gender-specific 95th percentile. Girls had 0.47 +/- 0.15 mmol/L higher LDL cholesterol, compared with boys (p = 0.002). Also in girls, HDL cholesterol increased by 0.07 +/- 0.03 mmol/L per 5 y (pfor trend = 0.005); this age effect was not observed in boys. The distribution of apolipoprotein (apo) E genotypes was not significantly different between probands, their paired affected siblings, or a Dutch control population. Carriers with or without one epsilon4 allele had similar LDL and HDL cholesterol levels. Within the affected sib-pairs, the epsilon4 allele explained 72.4% of the variance of HDL cholesterol levels (-0.15 mmol/L, 95% confidence interval -0.24 to -0.05, p = 0.003). The effect of apoE4 on HDL cholesterol differed with an analysis based on probands or on affected sib-pairs. The affected sib-pair model used adjustment for shared environment, type of LDL receptor gene mutation, and a proportion of additional genetic factors and may, therefore, be more accurate in estimating effects of risk factors on complex traits. We conclude that the epsilon4 allele was associated with lower HDL cholesterol levels in an affected sib-pair analysis, which strongly suggests that apoE4 influences HDL cholesterol levels in FH children. Moreover, the strong association suggests that apoE4 carries an additional disadvantage for FH children.

  11. Distribution of the HIV resistance CCR5-Delta32 allele among Egyptians and Syrians.

    PubMed

    Salem, Abdel-Halim; Batzer, Mark A

    2007-03-01

    A mutant allele of the beta-chemokine receptor gene CCR5 bearing a 32-basepair (bp) deletion that prevents cell invasion by the primary transmitting strain of HIV-1 has recently been characterized. Individuals homozygous for the mutation are resistant to infection, even after repeated high-risk exposure, but this resistance appears not absolute, as isolated cases of HIV-positive deletion homozygotes are emerging. The consequence of the heterozygous state is not clear, but it may delay the progression to AIDS in infected individuals. In order to evaluate the frequency distribution of CCR5-Delta32 polymorphism among Egyptians, a total of 200 individuals (154 from Ismailia and 46 from Sinai) were tested. Only two heterozygous individuals from Ismailia carried the CCR5-Delta32 allele (0.6%), and no homozygous (Delta32/Delta32) individuals were detected among the tested samples. The presence of the CCR5-Delta32 allele among Egyptians may be attributed to the admixture with people of European descent. Thus we conclude that the protective deletion CCR5-Delta32 is largely absent in the Egyptian population.

  12. The bipolar disorder risk allele at CACNA1C also confers risk of recurrent major depression and of schizophrenia.

    PubMed

    Green, E K; Grozeva, D; Jones, I; Jones, L; Kirov, G; Caesar, S; Gordon-Smith, K; Fraser, C; Forty, L; Russell, E; Hamshere, M L; Moskvina, V; Nikolov, I; Farmer, A; McGuffin, P; Holmans, P A; Owen, M J; O'Donovan, M C; Craddock, N

    2010-10-01

    Molecular genetic analysis offers opportunities to advance our understanding of the nosological relationship between psychiatric diagnostic categories in general, and the mood and psychotic disorders in particular. Strong evidence (P=7.0 × 10(-7)) of association at the polymorphism rs1006737 (within CACNA1C, the gene encoding the α-1C subunit of the L-type voltage-gated calcium channel) with the risk of bipolar disorder (BD) has recently been reported in a meta-analysis of three genome-wide association studies of BD, including our BD sample (N=1868) studied within the Wellcome Trust Case Control Consortium. Here, we have used our UK case samples of recurrent major depression (N=1196) and schizophrenia (N=479) and UK non-psychiatric comparison groups (N=15316) to examine the spectrum of phenotypic effect of the bipolar risk allele at rs1006737. We found that the risk allele conferred increased risk for schizophrenia (P=0.034) and recurrent major depression (P=0.013) with similar effect sizes to those previously observed in BD (allelic odds ratio ∼1.15). Our findings are evidence of some degree of overlap in the biological underpinnings of susceptibility to mental illness across the clinical spectrum of mood and psychotic disorders, and show that at least some loci can have a relatively general effect on susceptibility to diagnostic categories, as currently defined. Our findings will contribute to a better understanding of the pathogenesis of major psychiatric illness, and such knowledge should be useful in providing an etiological rationale for shaping psychiatric nosology, which is currently reliant entirely on descriptive clinical data.

  13. Geographical distribution of pyrethroid resistance allele frequency in head lice (Phthiraptera: Pediculidae) from Argentina.

    PubMed

    Toloza, Ariel Ceferino; Ascunce, Marina S; Reed, David; Picollo, María Inés

    2014-01-01

    The human head louse, Pediculus humanus capitis De Geer (Phthiraptera: Pediculidae), is an obligate ectoparasite that causes pediculosis capitis and has parasitized humans since the beginning of humankind. Head louse infestations are widespread throughout the world and have been increasing since the early 1990s partially because of ineffective pediculicides. In Argentina, the overuse of products containing pyrethroids has led to the development of resistant louse populations. Pyrethroid insecticides act on the nervous system affecting voltage-sensitive sodium channels. Three point mutations at the corresponding amino acid sequence positions M815I, T917I, and L920F in the voltage-gated sodium channel gene are responsible for contributing to knockdown resistance (kdr). The management of pyrethroid resistance requires either early detection or the characterization of the mechanisms involved in head louse populations. In the current study, we estimated the distribution of kdr alleles in 154 head lice from six geographical regions of Argentina. Pyrethroid resistance kdr alleles were found in high frequencies ranging from 67 to 100%. Of these, 131 (85.1%) were homozygous resistant, 13 (8.4%) were homozygous susceptible, and 10 (6.5%) were heterozygous. Exact tests for the Hardy-Weinberg equilibrium for each location showed that genotype frequencies differed significantly from expectation in four of the six sites studied. These results show that pyrethroid resistance is well established reaching an overall frequency of 88%, thus close to fixation. With 30 yr of pyrethroid-based pediculicides use in Argentina, kdr resistance has evolved rapidly among these head louse populations.

  14. Allelic variation on murine chromosome 11 modifies host inflammatory responses and resistance to Bacillus anthracis.

    PubMed

    Terra, Jill K; France, Bryan; Cote, Christopher K; Jenkins, Amy; Bozue, Joel A; Welkos, Susan L; Bhargava, Ragini; Ho, Chi-Lee; Mehrabian, Margarete; Pan, Calvin; Lusis, Aldons J; Davis, Richard C; LeVine, Steven M; Bradley, Kenneth A

    2011-12-01

    Anthrax is a potentially fatal disease resulting from infection with Bacillus anthracis. The outcome of infection is influenced by pathogen-encoded virulence factors such as lethal toxin (LT), as well as by genetic variation within the host. To identify host genes controlling susceptibility to anthrax, a library of congenic mice consisting of strains with homozygous chromosomal segments from the LT-responsive CAST/Ei strain introgressed on a LT-resistant C57BL/6 (B6) background was screened for response to LT. Three congenic strains containing CAST/Ei regions of chromosome 11 were identified that displayed a rapid inflammatory response to LT similar to, but more severe than that driven by a LT-responsive allele of the inflammasome constituent NRLP1B. Importantly, increased response to LT in congenic mice correlated with greater resistance to infection by the Sterne strain of B. anthracis. The genomic region controlling the inflammatory response to LT was mapped to 66.36-74.67 Mb on chromosome 11, a region that encodes the LT-responsive CAST/Ei allele of Nlrp1b. However, known downstream effects of NLRP1B activation, including macrophage pyroptosis, cytokine release, and leukocyte infiltration could not fully explain the response to LT or the resistance to B. anthracis Sterne in congenic mice. Further, the exacerbated response in congenic mice is inherited in a recessive manner while the Nlrp1b-mediated response to LT is dominant. Finally, congenic mice displayed increased responsiveness in a model of sepsis compared with B6 mice. In total, these data suggest that allelic variation of one or more chromosome 11 genes in addition to Nlrp1b controls the severity of host response to multiple inflammatory stimuli and contributes to resistance to B. anthracis Sterne. Expression quantitative trait locus analysis revealed 25 genes within this region as high priority candidates for contributing to the host response to LT.

  15. Frequency detection of imidacloprid resistance allele in Aphis gossypii field populations by real-time PCR amplification of specific-allele (rtPASA).

    PubMed

    Zhang, Jing; Cui, Li; Xu, Xibao; Rui, Changhui

    2015-11-01

    The Aphis gossypii Glover (Hemiptera: Aphididae) is one of the most serious pests worldwide, and imidacloprid has been widely used to control this insect pest. Just like other classes of insecticides, the resistance to imidacloprid has been found in A. gossypii. An amino acid mutation (R81T) in the nicotinic acetylcholine receptor (nAChR) beta1 subunit was detected in the imidacloprid-resistant A. gossypii collected from Langfang (LF) and Dezhou (DZ) cities. To estimate the R81T mutation frequency of A. gossypii field populations, a simple, rapid and accurate rtPASA (real-time PCR amplification of specific allele) protocol was developed. The performance of the rtPASA protocol was evaluated by comparing with the data generated by a cPASA (competitive PCR amplification of specific allele) method from 50 individual genotypes. The R81T allele frequencies of the LF population (34.7%±1.3%) and DZ population (45.2%±5.2%) estimated by the rtPASA protocol matched the frequencies (LF 38.1%, DZ 48.2%) deduced by the cPASA method in specimens. The results indicated that the rtPASA format was applicable for the detection of mutation associated with imidacloprid resistance and will allow rapid and efficient monitoring of A. gossypii resistance in field populations in a high throughput format.

  16. Mecillinam resistance in Escherichia coli is conferred by loss of a second activity of the AroK protein.

    PubMed Central

    Vinella, D; Gagny, B; Joseleau-Petit, D; D'Ari, R; Cashel, M

    1996-01-01

    Mecillinam, a beta-lactam antibiotic specific to penicillin-binding protein 2 (PBP 2) in Escherichia coli, blocks cell wall elongation and, indirectly, cell division, but its lethality can be overcome by increased levels of ppGpp, the nucleotide effector of the stringent response. We have subjected an E. coli K-12 strain to random insertional mutagenesis with a mini-Tn10 element. One insertion, which was found to confer resistance to mecillinam in relA+ and relA strains, was mapped at 75.5 min on the E. coli map and was located between the promoters and the coding sequence of the aroK gene, which codes for shikimate kinase 1, one of two E. coli shikimate kinases, both of which are involved in aromatic amino acid biosynthesis. The mecillinam resistance conferred by the insertion was abolished in a delta relA delta spoT strain completely lacking ppGpp, and it thus depends on the presence of ppGpp. Furthermore, the insertion increased the ppGpp pool approximately twofold in a relA+ strain. However, this increase was not observed in relA strains, although the insertion still conferred mecillinam resistance in these backgrounds, showing that mecillinam resistance is not due to an increased ppGpp pool. The resistance was also abolished in an ftsZ84(Ts) strain under semipermissive conditions, and the aroK::mini-Tn10 allele partially suppressed ftsZ84(Ts); however, it did not increase the concentration of the FtsZ cell division protein. The insertion greatly decreased or abolished the shikimate kinase activity of AroK in vivo and in vitro. The two shikimate kinases of E. coli are not equivalent; the loss of AroK confers mecillinam resistance, whereas the loss of Arol, does not. Furthermore, the ability of the aroK mutation to confer mecillinam resistance is shown to be independent of polar effects on operon expression and of effects on the availability of aromatic amino acids or shikimic acid. Instead, we conclude that the AroK protein has a second activity, possibly

  17. Mhc supertypes confer both qualitative and quantitative resistance to avian malaria infections in a wild bird population

    PubMed Central

    Sepil, Irem; Lachish, Shelly; Hinks, Amy E.; Sheldon, Ben C.

    2013-01-01

    Major histocompatibility complex (Mhc) genes are believed to play a key role in the genetic basis of disease control. Although numerous studies have sought links between Mhc and disease prevalence, many have ignored the ecological and epidemiological aspects of the host–parasite interaction. Consequently, interpreting associations between prevalence and Mhc has been difficult, whereas discriminating alleles for qualitative resistance, quantitative resistance and susceptibility remains challenging. Moreover, most studies to date have quantified associations between genotypes and disease status, overlooking the complex relationship between genotype and the properties of the Mhc molecule that interacts with parasites. Here, we address these problems and demonstrate avian malaria (Plasmodium) parasite species-specific associations with functional properties of Mhc molecules (Mhc supertypes) in a wild great tit (Parus major) population. We further show that correctly interpreting these associations depends crucially on understanding the spatial variation in risk of infection and the fitness effects of infection. We report that a single Mhc supertype confers qualitative resistance to Plasmodium relictum, whereas a different Mhc supertype confers quantitative resistance to Plasmodium circumflexum infections. Furthermore, we demonstrate common functional properties of Plasmodium-resistance alleles in passerine birds, suggesting this is a model system for parasite–Mhc associations in the wild. PMID:23516242

  18. Multiple alleles for resistance and susceptibility modulate the defense response in the interaction of tetraploid potato (Solanum tuberosum) with Synchytrium endobioticum pathotypes 1, 2, 6 and 18.

    PubMed

    Ballvora, Agim; Flath, Kerstin; Lübeck, Jens; Strahwald, Josef; Tacke, Eckhard; Hofferbert, Hans-Reinhard; Gebhardt, Christiane

    2011-12-01

    The obligate biotrophic, soil-borne fungus Synchytrium endobioticum causes wart disease of potato (Solanum tuberosum), which is a serious problem for crop production in countries with moderate climates. S. endobioticum induces hypertrophic cell divisions in plant host tissues leading to the formation of tumor-like structures. Potato wart is a quarantine disease and chemical control is not possible. From 38 S. endobioticum pathotypes occurring in Europe, pathotypes 1, 2, 6 and 18 are the most relevant. Genetic resistance to wart is available but only few current potato varieties are resistant to all four pathotypes. The phenotypic evaluation of wart resistance is laborious, time-consuming and sometimes ambiguous, which makes breeding for resistance difficult. Molecular markers diagnostic for genes for resistance to S. endobioticum pathotypes 1, 2, 6 and 18 would greatly facilitate the selection of new, resistant cultivars. Two tetraploid half-sib families (266 individuals) segregating for resistance to S. endobioticum pathotypes 1, 2, 6 and 18 were produced by crossing a resistant genotype with two different susceptible ones. The families were scored for five different wart resistance phenotypes. The distribution of mean resistance scores was quantitative in both families. Resistance to pathotypes 2, 6 and 18 was correlated and independent from resistance to pathotype 1. DNA pools were constructed from the most resistant and most susceptible individuals and screened with genome wide simple sequence repeat (SSR), inverted simple sequence region (ISSR) and randomly amplified polymorphic DNA (RAPD) markers. Bulked segregant analysis identified three SSR markers that were linked to wart resistance loci (Sen). Sen1-XI on chromosome XI conferred partial resistance to pathotype 1, Sen18-IX on chromosome IX to pathotype 18 and Sen2/6/18-I on chromosome I to pathotypes 2,6 and 18. Additional genotyping with 191 single nucleotide polymorphism (SNP) markers confirmed the

  19. Historical Shifts in Brazilian P. falciparum Population Structure and Drug Resistance Alleles

    PubMed Central

    Griffing, Sean M.; Viana, Giselle M. Rachid; Mixson-Hayden, Tonya; Sridaran, Sankar; Alam, Mohammad Tauqeer; de Oliveira, Alexandre Macedo; Barnwell, John W.; Escalante, Ananias A.; Povoa, Marinete Marins; Udhayakumar, Venkatachalam

    2013-01-01

    Previous work suggests that Brazilian Plasmodium falciparum has limited genetic diversity and a history of bottlenecks, multiple reintroductions due to human migration, and clonal expansions. We hypothesized that Brazilian P. falciparum would exhibit clonal structure. We examined isolates collected across two decades from Amapá, Rondônia, and Pará state (n = 190). By examining more microsatellites markers on more chromosomes than previous studies, we hoped to define the extent of low diversity, linkage disequilibrium, bottlenecks, population structure, and parasite migration within Brazil. We used retrospective genotyping of samples from the 1980s and 1990s to explore the population genetics of SP resistant dhfr and dhps alleles. We tested an existing hypothesis that the triple mutant dhfr mutations 50R/51I/108N and 51I/108N/164L developed in southern Amazon from a single origin of common or similar parasites. We found that Brazilian P. falciparum had limited genetic diversity and isolation by distance was rejected, which suggests it underwent bottlenecks followed by migration between sites. Unlike Peru, there appeared to be gene flow across the Brazilian Amazon basin. We were unable to divide parasite populations by clonal lineages and pairwise FST were common. Most parasite diversity was found within sites in the Brazilian Amazon, according to AMOVA. Our results challenge the hypothesis that triple mutant alleles arose from a single lineage in the Southern Amazon. SP resistance, at both the double and triple mutant stages, developed twice and potentially in different regions of the Brazilian Amazon. We would have required samples from before the 1980s to describe how SP resistance spread across the basin or describe the complex internal migration of Brazilian parasites after the colonization efforts of past decades. The Brazilian Amazon basin may have sufficient internal migration for drug resistance reported in any particular region to rapidly spread to

  20. Initial frequency of alleles for resistance to Bacillus thuringiensis toxins in field populations of Heliothis virescens

    PubMed Central

    Gould, F.; Anderson, A.; Jones, A.; Sumerford, D.; Heckel, D. G.; Lopez, J.; Micinski, S.; Leonard, R.; Laster, M.

    1997-01-01

    The risk of rapid pest adaptation to an insecticide is highly dependent on the initial frequency of resistance alleles in field populations. Because we have lacked empirical estimates of these frequencies, population–genetic models of resistance evolution have relied on a wide range of theoretical estimates. The recent commercialization of genetically engineered cotton that constitutively produces an insecticidal protein derived from the biocontrol agent, Bacillus thuringiensis (Bt) has raised concern that we lack data needed to quantify the risk of insect pests such as Heliothis virescens rapidly adapting to this ecologically valuable class of toxins. By individually mating over 2,000 male H. virescens moths collected in four states to females of a Bt toxin-resistant laboratory strain, and screening F1 and F2 offspring for tolerance of the toxic protein, we were able to directly estimate the field frequency of alleles for resistance as 1.5 × 10−3. This high initial frequency underscores the need for caution in deploying transgenic cotton to control insect pests. Our single-pair mating technique greatly increases the efficiency of detecting recessive resistance alleles. Because alleles that decrease target site sensitivity to Bt toxins and other insecticides are often recessive, this technique could be useful in estimating resistance allele frequencies in other insects exposed to transgenic insecticidal crops or conventional insecticides. PMID:11038613

  1. Mutant alleles of Photoperiod-1 in wheat (Triticum aestivum L.) that confer a late flowering phenotype in long days.

    PubMed

    Shaw, Lindsay M; Turner, Adrian S; Herry, Laurence; Griffiths, Simon; Laurie, David A

    2013-01-01

    Flowering time in wheat and barley is known to be modified by mutations in the Photoperiod-1 (Ppd-1) gene. Semi-dominant Ppd-1a mutations conferring an early flowering phenotype are well documented in wheat but gene sequencing has also identified candidate loss of function mutations for Ppd-A1 and Ppd-D1. By analogy to the recessive ppd-H1 mutation in barley, loss of function mutations in wheat are predicted to delay flowering under long day conditions. To test this experimentally, introgression lines were developed in the spring wheat variety 'Paragon'. Plants lacking a Ppd-B1 gene were identified from a gamma irradiated 'Paragon' population. These were crossed with the other introgression lines to generate plants with candidate loss of function mutations on one, two or three genomes. Lines lacking Ppd-B1 flowered 10 to 15 days later than controls under long days. Candidate loss of function Ppd-A1 alleles delayed flowering by 1 to 5 days while candidate loss of function Ppd-D1 alleles did not affect flowering time. Loss of Ppd-A1 gave an enhanced effect, and loss of Ppd-D1 became detectable in lines where Ppd-B1 was absent, indicating effects may be buffered by functional Ppd-1 alleles on other genomes. Expression analysis revealed that delayed flowering was associated with reduced expression of the TaFT1 gene and increased expression of TaCO1. A survey of the GEDIFLUX wheat collection grown in the UK and North Western Europe between the 1940s and 1980s and the A.E. Watkins global collection of landraces from the 1920s and 1930s showed that the identified candidate loss of function mutations for Ppd-D1 were common and widespread, while the identified candidate Ppd-A1 loss of function mutation was rare in countries around the Mediterranean and in the Far East but was common in North Western Europe. This may reflect a possible benefit of the latter in northern locations.

  2. Multiple rare alleles at LDLR and APOA5 confer risk for early-onset myocardial infarction

    PubMed Central

    Do, Ron; Stitziel, Nathan O.; Won, Hong-Hee; Jørgensen, Anders Berg; Duga, Stefano; Merlini, Pier Angelica; Kiezun, Adam; Farrall, Martin; Goel, Anuj; Zuk, Or; Guella, Illaria; Asselta, Rosanna; Lange, Leslie A.; Peloso, Gina M.; Auer, Paul L.; Girelli, Domenico; Martinelli, Nicola; Farlow, Deborah N.; DePristo, Mark A.; Roberts, Robert; Stewart, Alexander F.R.; Saleheen, Danish; Danesh, John; Epstein, Stephen E.; Sivapalaratnam, Suthesh; Hovingh, G. Kees; Kastelein, John J.; Samani, Nilesh J.; Schunkert, Heribert; Erdmann, Jeanette; Shah, Svati H.; Kraus, William E.; Davies, Robert; Nikpay, Majid; Johansen, Christopher T.; Wang, Jian; Hegele, Robert A.; Hechter, Eliana; Marz, Winfried; Kleber, Marcus E.; Huang, Jie; Johnson, Andrew D.; Li, Mingyao; Burke, Greg L.; Gross, Myron; Liu, Yongmei; Assimes, Themistocles L.; Heiss, Gerardo; Lange, Ethan M.; Folsom, Aaron R.; Taylor, Herman A.; Olivieri, Oliviero; Hamsten, Anders; Clarke, Robert; Reilly, Dermot F.; Yin, Wu; Rivas, Manuel A.; Donnelly, Peter; Rossouw, Jacques E.; Psaty, Bruce M.; Herrington, David M.; Wilson, James G.; Rich, Stephen S.; Bamshad, Michael J.; Tracy, Russell P.; Cupples, L. Adrienne; Rader, Daniel J.; Reilly, Muredach P.; Spertus, John A.; Cresci, Sharon; Hartiala, Jaana; Tang, W.H. Wilson; Hazen, Stanley L.; Allayee, Hooman; Reiner, Alex P.; Carlson, Christopher S.; Kooperberg, Charles; Jackson, Rebecca D.; Boerwinkle, Eric; Lander, Eric S.; Schwartz, Stephen M.; Siscovick, David S.; McPherson, Ruth; Tybjaerg-Hansen, Anne; Abecasis, Goncalo R.; Watkins, Hugh; Nickerson, Deborah A.; Ardissino, Diego; Sunyaev, Shamil R.; O’Donnell, Christopher J.; Altshuler, David; Gabriel, Stacey; Kathiresan, Sekar

    2014-01-01

    Summary Myocardial infarction (MI), a leading cause of death around the world, displays a complex pattern of inheritance1,2. When MI occurs early in life, the role of inheritance is substantially greater1. Previously, rare mutations in low-density lipoprotein (LDL) genes have been shown to contribute to MI risk in individual families3–8 whereas common variants at more than 45 loci have been associated with MI risk in the population9–15. Here, we evaluate the contribution of rare mutations to MI risk in the population. We sequenced the protein-coding regions of 9,793 genomes from patients with MI at an early age (≤50 years in males and ≤60 years in females) along with MI-free controls. We identified two genes where rare coding-sequence mutations were more frequent in cases versus controls at exome-wide significance. At low-density lipoprotein receptor (LDLR), carriers of rare, damaging mutations (3.1% of cases versus 1.3% of controls) were at 2.4-fold increased risk for MI; carriers of null alleles at LDLR were at even higher risk (13-fold difference). This sequence-based estimate of the proportion of early MI cases due to LDLR mutations is remarkably similar to an estimate made more than 40 years ago using total cholesterol16. At apolipoprotein A-V (APOA5), carriers of rare nonsynonymous mutations (1.4% of cases versus 0.6% of controls) were at 2.2-fold increased risk for MI. When compared with non-carriers, LDLR mutation carriers had higher plasma LDL cholesterol whereas APOA5 mutation carriers had higher plasma triglycerides. Recent evidence has connected MI risk with coding sequence mutations at two genes functionally related to APOA5, namely lipoprotein lipase15,17 and apolipoprotein C318,19. When combined, these observations suggest that, beyond LDL cholesterol, disordered metabolism of triglyceride-rich lipoproteins contributes to MI risk. PMID:25487149

  3. Exome sequencing identifies rare LDLR and APOA5 alleles conferring risk for myocardial infarction.

    PubMed

    Do, Ron; Stitziel, Nathan O; Won, Hong-Hee; Jørgensen, Anders Berg; Duga, Stefano; Angelica Merlini, Pier; Kiezun, Adam; Farrall, Martin; Goel, Anuj; Zuk, Or; Guella, Illaria; Asselta, Rosanna; Lange, Leslie A; Peloso, Gina M; Auer, Paul L; Girelli, Domenico; Martinelli, Nicola; Farlow, Deborah N; DePristo, Mark A; Roberts, Robert; Stewart, Alexander F R; Saleheen, Danish; Danesh, John; Epstein, Stephen E; Sivapalaratnam, Suthesh; Hovingh, G Kees; Kastelein, John J; Samani, Nilesh J; Schunkert, Heribert; Erdmann, Jeanette; Shah, Svati H; Kraus, William E; Davies, Robert; Nikpay, Majid; Johansen, Christopher T; Wang, Jian; Hegele, Robert A; Hechter, Eliana; Marz, Winfried; Kleber, Marcus E; Huang, Jie; Johnson, Andrew D; Li, Mingyao; Burke, Greg L; Gross, Myron; Liu, Yongmei; Assimes, Themistocles L; Heiss, Gerardo; Lange, Ethan M; Folsom, Aaron R; Taylor, Herman A; Olivieri, Oliviero; Hamsten, Anders; Clarke, Robert; Reilly, Dermot F; Yin, Wu; Rivas, Manuel A; Donnelly, Peter; Rossouw, Jacques E; Psaty, Bruce M; Herrington, David M; Wilson, James G; Rich, Stephen S; Bamshad, Michael J; Tracy, Russell P; Cupples, L Adrienne; Rader, Daniel J; Reilly, Muredach P; Spertus, John A; Cresci, Sharon; Hartiala, Jaana; Tang, W H Wilson; Hazen, Stanley L; Allayee, Hooman; Reiner, Alex P; Carlson, Christopher S; Kooperberg, Charles; Jackson, Rebecca D; Boerwinkle, Eric; Lander, Eric S; Schwartz, Stephen M; Siscovick, David S; McPherson, Ruth; Tybjaerg-Hansen, Anne; Abecasis, Goncalo R; Watkins, Hugh; Nickerson, Deborah A; Ardissino, Diego; Sunyaev, Shamil R; O'Donnell, Christopher J; Altshuler, David; Gabriel, Stacey; Kathiresan, Sekar

    2015-02-05

    Myocardial infarction (MI), a leading cause of death around the world, displays a complex pattern of inheritance. When MI occurs early in life, genetic inheritance is a major component to risk. Previously, rare mutations in low-density lipoprotein (LDL) genes have been shown to contribute to MI risk in individual families, whereas common variants at more than 45 loci have been associated with MI risk in the population. Here we evaluate how rare mutations contribute to early-onset MI risk in the population. We sequenced the protein-coding regions of 9,793 genomes from patients with MI at an early age (≤50 years in males and ≤60 years in females) along with MI-free controls. We identified two genes in which rare coding-sequence mutations were more frequent in MI cases versus controls at exome-wide significance. At low-density lipoprotein receptor (LDLR), carriers of rare non-synonymous mutations were at 4.2-fold increased risk for MI; carriers of null alleles at LDLR were at even higher risk (13-fold difference). Approximately 2% of early MI cases harbour a rare, damaging mutation in LDLR; this estimate is similar to one made more than 40 years ago using an analysis of total cholesterol. Among controls, about 1 in 217 carried an LDLR coding-sequence mutation and had plasma LDL cholesterol > 190 mg dl(-1). At apolipoprotein A-V (APOA5), carriers of rare non-synonymous mutations were at 2.2-fold increased risk for MI. When compared with non-carriers, LDLR mutation carriers had higher plasma LDL cholesterol, whereas APOA5 mutation carriers had higher plasma triglycerides. Recent evidence has connected MI risk with coding-sequence mutations at two genes functionally related to APOA5, namely lipoprotein lipase and apolipoprotein C-III (refs 18, 19). Combined, these observations suggest that, as well as LDL cholesterol, disordered metabolism of triglyceride-rich lipoproteins contributes to MI risk.

  4. The dynamic influence of the DRB1*1101 allele on the resistance of sheep to experimental Teladorsagia circumcincta infection.

    PubMed

    Hassan, Musa; Good, Barbara; Hanrahan, James P; Campion, Deirdre; Sayers, Gearoid; Mulcahy, Grace; Sweeney, Torres

    2011-03-08

    Suffolk sheep carrying the DRB1*1101 (previously referred to as-DRB1*0203 or G2) allele have been reported to show increased resistance to natural Teladorsagia circumcincta infection compared to non-carriers. The objective of this study was to compare the biochemical and physiological responses of DRB1*1101 carrier and non-carrier twin lambs to an experimental infection with 3 × 10(4) L3 Teladorsagia circumcincta. The variables studied included worm burden, faecal egg count, abomasal mast cells, IgA, IgE, IgG1 plus IgG2 and haematological parameters at 0, 3, 7, 21 and 35 days post infection (dpi), and duodenal smooth muscle contractility at 0 and 35 dpi. DRB1*1101 carrier lambs had significantly lower worm burden, higher mast cell and plasma platelet counts than the DRB1*1101 non-carriers (P < 0.05). Before infection, the non-carrier lambs exhibited significantly higher mucosal levels of all antibody isotypes measured compared to the carriers; these levels remained relatively stable over the course of infection in the non-carriers while there was a slow build up of these antibodies in the carriers up to day 21 post infection (pi). The DRB1*1101 non-carrier lambs had a significantly higher plasma lymphocyte count, and produced greater duodenal contractile force relative to the carrier lambs (P < 0.05). There was no significant difference between genotypes in the level of plasma eosinophils, monocytes, neutrophils or FEC. This evidence suggests that resistance conferred by DRB1*1101 is acquired rather than innate, depends on worm expulsion rather than fecundity and is dependent on mucosal mast cell proliferation, platelet activation, and IgA and IgE antibody responses.

  5. The dynamic influence of the DRB1*1101 allele on the resistance of sheep to experimental Teladorsagia circumcincta infection

    PubMed Central

    2011-01-01

    Suffolk sheep carrying the DRB1*1101 (previously referred to as-DRB1*0203 or G2) allele have been reported to show increased resistance to natural Teladorsagia circumcincta infection compared to non-carriers. The objective of this study was to compare the biochemical and physiological responses of DRB1*1101 carrier and non-carrier twin lambs to an experimental infection with 3 × 104 L3 Teladorsagia circumcincta. The variables studied included worm burden, faecal egg count, abomasal mast cells, IgA, IgE, IgG1 plus IgG2 and haematological parameters at 0, 3, 7, 21 and 35 days post infection (dpi), and duodenal smooth muscle contractility at 0 and 35 dpi. DRB1*1101 carrier lambs had significantly lower worm burden, higher mast cell and plasma platelet counts than the DRB1*1101 non-carriers (P < 0.05). Before infection, the non-carrier lambs exhibited significantly higher mucosal levels of all antibody isotypes measured compared to the carriers; these levels remained relatively stable over the course of infection in the non-carriers while there was a slow build up of these antibodies in the carriers up to day 21 post infection (pi). The DRB1*1101 non-carrier lambs had a significantly higher plasma lymphocyte count, and produced greater duodenal contractile force relative to the carrier lambs (P < 0.05). There was no significant difference between genotypes in the level of plasma eosinophils, monocytes, neutrophils or FEC. This evidence suggests that resistance conferred by DRB1*1101 is acquired rather than innate, depends on worm expulsion rather than fecundity and is dependent on mucosal mast cell proliferation, platelet activation, and IgA and IgE antibody responses. PMID:21385412

  6. Inheritance and molecular mapping of a gene conferring seedling resistance against Puccinia hordei in the barley cultivar Ricardo.

    PubMed

    Sandhu, K S; Forrest, K L; Kong, S; Bansal, U K; Singh, D; Hayden, M J; Park, R F

    2012-11-01

    Genetic studies were undertaken to determine the inheritance and genomic location of uncharacterised seedling resistance to leaf rust, caused by Puccinia hordei, in the barley cultivar Ricardo. The resistance was shown to be conferred by a single dominant gene, which was tentatively designated RphRic. Bulk segregant analysis (BSA) and genetic mapping of an F(3) mapping population using multiplex-ready SSR genotyping and Illumina GoldenGate SNP assay located RphRic in chromosome 4H. Given that this is the first gene for leaf rust resistance mapped on chromosome 4H, it was designated Rph21. The presence of an additional gene, Rph2, in Ricardo, was confirmed by the test of allelism. The seedling gene Rph21 has shown effectiveness against all Australian pathotypes of P. hordei tested since at least 1992 and hence represents a new and useful source of resistance to this pathogen.

  7. Ancestral QTL Alleles from Wild Emmer Wheat Improve Drought Resistance and Productivity in Modern Wheat Cultivars

    PubMed Central

    Merchuk-Ovnat, Lianne; Barak, Vered; Fahima, Tzion; Ordon, Frank; Lidzbarsky, Gabriel A.; Krugman, Tamar; Saranga, Yehoshua

    2016-01-01

    Wild emmer wheat (Triticum turgidum ssp. dicoccoides) is considered a promising source for improving stress resistances in domesticated wheat. Here we explored the potential of selected quantitative trait loci (QTLs) from wild emmer wheat, introgressed via marker-assisted selection, to enhance drought resistance in elite durum (T. turgidum ssp. durum) and bread (T. aestivum) wheat cultivars. The resultant near-isogenic lines (BC3F3 and BC3F4) were genotyped using SNP array to confirm the introgressed genomic regions and evaluated in two consecutive years under well-watered (690–710 mm) and water-limited (290–320 mm) conditions. Three of the introgressed QTLs were successfully validated, two in the background of durum wheat cv. Uzan (on chromosomes 1BL and 2BS), and one in the background of bread wheat cvs. Bar Nir and Zahir (chromosome 7AS). In most cases, the QTL x environment interaction was validated in terms of improved grain yield and biomass—specifically under drought (7AS QTL in cv. Bar Nir background), under both treatments (2BS QTL), and a greater stability across treatments (1BL QTL). The results provide a first demonstration that introgression of wild emmer QTL alleles can enhance productivity and yield stability across environments in domesticated wheat, thereby enriching the modern gene pool with essential diversity for the improvement of drought resistance. PMID:27148287

  8. Ancestral QTL Alleles from Wild Emmer Wheat Improve Drought Resistance and Productivity in Modern Wheat Cultivars.

    PubMed

    Merchuk-Ovnat, Lianne; Barak, Vered; Fahima, Tzion; Ordon, Frank; Lidzbarsky, Gabriel A; Krugman, Tamar; Saranga, Yehoshua

    2016-01-01

    Wild emmer wheat (Triticum turgidum ssp. dicoccoides) is considered a promising source for improving stress resistances in domesticated wheat. Here we explored the potential of selected quantitative trait loci (QTLs) from wild emmer wheat, introgressed via marker-assisted selection, to enhance drought resistance in elite durum (T. turgidum ssp. durum) and bread (T. aestivum) wheat cultivars. The resultant near-isogenic lines (BC3F3 and BC3F4) were genotyped using SNP array to confirm the introgressed genomic regions and evaluated in two consecutive years under well-watered (690-710 mm) and water-limited (290-320 mm) conditions. Three of the introgressed QTLs were successfully validated, two in the background of durum wheat cv. Uzan (on chromosomes 1BL and 2BS), and one in the background of bread wheat cvs. Bar Nir and Zahir (chromosome 7AS). In most cases, the QTL x environment interaction was validated in terms of improved grain yield and biomass-specifically under drought (7AS QTL in cv. Bar Nir background), under both treatments (2BS QTL), and a greater stability across treatments (1BL QTL). The results provide a first demonstration that introgression of wild emmer QTL alleles can enhance productivity and yield stability across environments in domesticated wheat, thereby enriching the modern gene pool with essential diversity for the improvement of drought resistance.

  9. Acquisition of a single EZH2 D1 domain mutation confers acquired resistance to EZH2-targeted inhibitors

    PubMed Central

    Baker, Theresa; Nerle, Sujata; Pritchard, Justin; Zhao, Boyang; Rivera, Victor M.

    2015-01-01

    Although targeted therapies have revolutionized cancer treatment, overcoming acquired resistance remains a major clinical challenge. EZH2 inhibitors (EZH2i), EPZ-6438 and GSK126, are currently in the early stages of clinical evaluation and the first encouraging signs of efficacy have recently emerged in the clinic. To anticipate mechanisms of resistance to EZH2i, we used a forward genetic platform combining a mutagenesis screen with next generation sequencing technology and identified a hotspot of secondary mutations in the EZH2 D1 domain (Y111 and I109). Y111D mutation within the WT or A677G EZH2 allele conferred robust resistance to both EPZ-6438 and GSK126, but it only drove a partial resistance within the Y641F allele. EZH2 mutants required histone methyltransferase (HMT) catalytic activity and the polycomb repressive complex 2 (PRC2) components, SUZ12 and EED, to drive drug resistance. Furthermore, D1 domain mutations not only blocked the ability of EZH2i to bind to WT and A677G mutant, but also abrogated drug binding to the Y641F mutant. These data provide the first cellular validation of the mechanistic model underpinning the oncogenic function of WT and mutant EZH2. Importantly, our findings suggest that acquired-resistance to EZH2i may arise in WT and mutant EZH2 patients through a single mutation that remains targetable by second generation EZH2i. PMID:26360609

  10. Ribosomal Mutations in Arcanobacterium pyogenes Confer a Unique Spectrum of Macrolide Resistance

    PubMed Central

    Jost, B. Helen; Trinh, Hien T.; Songer, J. Glenn; Billington, Stephen J.

    2004-01-01

    Four macrolide-resistant Arcanobacterium pyogenes isolates contained A2058T, A2058G, or C2611G (Escherichia coli numbering) mutations in their 23S rRNA genes. While these mutations conferred resistance to erythromycin, oleandomycin, and spiramycin, they did not confer resistance to tylosin. PMID:14982799

  11. Association of BoLA-DRB3.2 alleles with tick (Boophilus microplus) resistance in cattle.

    PubMed

    Martinez, M L; Machado, M A; Nascimento, C S; Silva, M V G B; Teodoro, R L; Furlong, J; Prata, M C A; Campos, A L; Guimarães, M F M; Azevedo, A L S; Pires, M F A; Verneque, R S

    2006-08-31

    Losses caused by bovine tick burdens in tropical countries have a tremendous economic impact on production systems. Besides reducing production, this parasite can cause death in the most susceptible animals. The use of commercial acaricides has been the major method of control, but their misuse has led to tick resistance to many chemicals. More recently, vaccines have been used in some countries without solving the problem completely. An alternative could be the development of resistant animals and the use of genetic markers and candidate genes that could help with the enormous task of selecting resistant animals. The bovine lymphocyte antigen genes (BoLA) have been shown to be associated with some parasitic infestations and disease incidence. Thus, the objective of the present study was to determine the association of BoLA-DRB3.2 alleles with tick resistance in cattle. The study was conducted on 231 F2 (Gyr x Holstein) animals that were artificially infested with 10,000 tick larvae. Log of tick count +1 was used as the dependent variable in a mixed animal model with allele substitution effects in addition to fixed effects of year and season at tick count, sex of calves, age of animal at tick count, hair type (short-straight, short-curl, long-straight, and long-curl), coat color (white, >75% white, 50- 75% white, and 25-50% white), and additive genetic, permanent environmental and residual effects as random. Females showed fewer ticks than males. Animals with short-straight hair were more resistant to tick infestation than animals with long-curl hair, and animals with whiter coat color also had fewer ticks. An association between BoLA alleles and lower tick number was found for alleles DRB3.2 *18, *20 and *27 at the 5% significance level. Also, one allele (DRB3.2*16) showed an association at the 10% level. Allele *27 was the most frequent in the population (30.7%), followed by alleles *16 (10.8%), *20 (8.7%) and *18 (2.4%). These results suggest that BoLA-DRB3

  12. Molecular characterization and a multiplex allele-specific PCR method for detection of thiabendazole resistance in Penicillium expansum from apple

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Thiabendazole (TBZ) is commonly used as a postharvest treatment for control of blue mold in apples caused by Penicillium expansum. Different point mutations in the ß-tubulin gene conferring benzimidazole resistance have been reported in plant pathogens, but molecular mechanisms of TBZ resistance in ...

  13. Evolution of Fitness Cost-Neutral Mutant PfCRT Conferring P. falciparum 4-Aminoquinoline Drug Resistance Is Accompanied by Altered Parasite Metabolism and Digestive Vacuole Physiology

    PubMed Central

    Gabryszewski, Stanislaw J.; Dhingra, Satish K.; Lewis, Ian A.; Callaghan, Paul S.; Hassett, Matthew R.; Siriwardana, Amila; Henrich, Philipp P.; Lee, Andrew H.; Gnädig, Nina F.; Musset, Lise; Llinás, Manuel; Egan, Timothy J.; Roepe, Paul D.

    2016-01-01

    Southeast Asia is an epicenter of multidrug-resistant Plasmodium falciparum strains. Selective pressures on the subcontinent have recurrently produced several allelic variants of parasite drug resistance genes, including the P. falciparum chloroquine resistance transporter (pfcrt). Despite significant reductions in the deployment of the 4-aminoquinoline drug chloroquine (CQ), which selected for the mutant pfcrt alleles that halted CQ efficacy decades ago, the parasite pfcrt locus is continuously evolving. This is highlighted by the presence of a highly mutated allele, Cam734 pfcrt, which has acquired the singular ability to confer parasite CQ resistance without an associated fitness cost. Here, we used pfcrt-specific zinc-finger nucleases to genetically dissect this allele in the pathogenic setting of asexual blood-stage infection. Comparative analysis of drug resistance and growth profiles of recombinant parasites that express Cam734 or variants thereof, Dd2 (the most common Southeast Asian variant), or wild-type pfcrt, revealed previously unknown roles for PfCRT mutations in modulating parasite susceptibility to multiple antimalarial agents. These results were generated in the GC03 strain, used in multiple earlier pfcrt studies, and might differ in natural isolates harboring this allele. Results presented herein show that Cam734-mediated CQ resistance is dependent on the rare A144F mutation that has not been observed beyond Southeast Asia, and reveal distinct impacts of this and other Cam734-specific mutations on CQ resistance and parasite growth rates. Biochemical assays revealed a broad impact of mutant PfCRT isoforms on parasite metabolism, including nucleoside triphosphate levels, hemoglobin catabolism and disposition of heme, as well as digestive vacuole volume and pH. Results from our study provide new insights into the complex molecular basis and physiological impact of PfCRT-mediated antimalarial drug resistance, and inform ongoing efforts to characterize

  14. Food supply confers calcifiers resistance to ocean acidification.

    PubMed

    Ramajo, Laura; Pérez-León, Elia; Hendriks, Iris E; Marbà, Núria; Krause-Jensen, Dorte; Sejr, Mikael K; Blicher, Martin E; Lagos, Nelson A; Olsen, Ylva S; Duarte, Carlos M

    2016-01-18

    Invasion of ocean surface waters by anthropogenic CO2 emitted to the atmosphere is expected to reduce surface seawater pH to 7.8 by the end of this century compromising marine calcifiers. A broad range of biological and mineralogical mechanisms allow marine calcifiers to cope with ocean acidification, however these mechanisms are energetically demanding which affect other biological processes (trade-offs) with important implications for the resilience of the organisms against stressful conditions. Hence, food availability may play a critical role in determining the resistance of calcifiers to OA. Here we show, based on a meta-analysis of existing experimental results assessing the role of food supply in the response of organisms to OA, that food supply consistently confers calcifiers resistance to ocean acidification.

  15. Food supply confers calcifiers resistance to ocean acidification

    PubMed Central

    Ramajo, Laura; Pérez-León, Elia; Hendriks, Iris E.; Marbà, Núria; Krause-Jensen, Dorte; Sejr, Mikael K.; Blicher, Martin E.; Lagos, Nelson A.; Olsen, Ylva S.; Duarte, Carlos M.

    2016-01-01

    Invasion of ocean surface waters by anthropogenic CO2 emitted to the atmosphere is expected to reduce surface seawater pH to 7.8 by the end of this century compromising marine calcifiers. A broad range of biological and mineralogical mechanisms allow marine calcifiers to cope with ocean acidification, however these mechanisms are energetically demanding which affect other biological processes (trade-offs) with important implications for the resilience of the organisms against stressful conditions. Hence, food availability may play a critical role in determining the resistance of calcifiers to OA. Here we show, based on a meta-analysis of existing experimental results assessing the role of food supply in the response of organisms to OA, that food supply consistently confers calcifiers resistance to ocean acidification. PMID:26778520

  16. Food supply confers calcifiers resistance to ocean acidification

    NASA Astrophysics Data System (ADS)

    Ramajo, Laura; Pérez-León, Elia; Hendriks, Iris E.; Marbà, Núria; Krause-Jensen, Dorte; Sejr, Mikael K.; Blicher, Martin E.; Lagos, Nelson A.; Olsen, Ylva S.; Duarte, Carlos M.

    2016-01-01

    Invasion of ocean surface waters by anthropogenic CO2 emitted to the atmosphere is expected to reduce surface seawater pH to 7.8 by the end of this century compromising marine calcifiers. A broad range of biological and mineralogical mechanisms allow marine calcifiers to cope with ocean acidification, however these mechanisms are energetically demanding which affect other biological processes (trade-offs) with important implications for the resilience of the organisms against stressful conditions. Hence, food availability may play a critical role in determining the resistance of calcifiers to OA. Here we show, based on a meta-analysis of existing experimental results assessing the role of food supply in the response of organisms to OA, that food supply consistently confers calcifiers resistance to ocean acidification.

  17. Insecticide resistance in house flies from the United States: Resistance levels and frequency of pyrethroid resistance alleles

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although insecticide resistance is a widespread problem for most insect pests, frequently the assessment of resistance occurs over a limited geographic range. Herein we report the first widespread survey of insecticide resistance ever undertaken for the house fly, Musca domestica, a major pest of a...

  18. Allelic variation in TLR4 is linked to resistance to Salmonella Enteritidis infection in chickens.

    PubMed

    Li, Peng; Wang, Huihua; Zhao, Xingwang; Gou, Zhongyong; Liu, Ranran; Song, Yongmei; Li, Qinghe; Zheng, Maiqing; Cui, Huanxian; Everaert, Nadia; Zhao, Guiping; Wen, Jie

    2017-03-01

    Salmonella Enteritidis (SE) is a foodborne pathogen that negatively affects both animal and human health. Polymorphisms of the TLR4 gene may affect recognition by Toll-like receptor 4 (TLR4) of bacterial lipopolysaccharide (LPS), leading to differences in host resistance to pathogenic infections. The present study has investigated polymorphic loci of chicken TLR4 (ChTLR4) in ten chicken breeds, electrostatic potentials of mutant structures of TLR4, and a linkage analysis between allelic variation and survival ratio to infection with SE in specific-pathogen-free (SPF) White Leghorns. A total of 19 Single Nucleotide Polymorphisms (SNPs), of which 10 were novel, were found in chicken breeds. Seven newly identified amino acid variants (C68G, G674A, G782A, A896T, T959G, T986A, and A1104C) and previously reported important mutations (G247A, G1028A, C1147T, and A1832G) were demonstrated in the extracellular domain of the ChTLR4 gene. Significant changes in surface electrostatic potential of the ectodomain of TLR4, built by homology modeling, were observed at the Glu83Lys (G247A), Arg298Ser (A896T), Ser368Arg (A1104C), and Gln611Arg (A1832G) substitutions. Linkage analysis showed that one polymorphic locus G247A of TLR4 gene, common in all breeds examined, was significantly associated with increased resistance to SE in SPF White Leghorns chicks (log-rank P-value = 0.04). The genotypes from A1832G SNPs did not show statistically significant survival differences. This study has provided the first direct evidence that G247A substitution in ChTLR4 is associated with increased resistance to Salmonella Enteritidis.

  19. Chromosomal DNA deletion confers phage resistance to Pseudomonas aeruginosa.

    PubMed

    Le, Shuai; Yao, Xinyue; Lu, Shuguang; Tan, Yinling; Rao, Xiancai; Li, Ming; Jin, Xiaolin; Wang, Jing; Zhao, Yan; Wu, Nicholas C; Lux, Renate; He, Xuesong; Shi, Wenyuan; Hu, Fuquan

    2014-04-28

    Bacteria develop a broad range of phage resistance mechanisms, such as prevention of phage adsorption and CRISPR/Cas system, to survive phage predation. In this study, Pseudomonas aeruginosa PA1 strain was infected with lytic phage PaP1, and phage-resistant mutants were selected. A high percentage (~30%) of these mutants displayed red pigmentation phenotype (Red mutant). Through comparative genomic analysis, one Red mutant PA1r was found to have a 219.6 kb genomic fragment deletion, which contains two key genes hmgA and galU related to the observed phenotypes. Deletion of hmgA resulted in the accumulation of a red compound homogentisic acid; while A galU mutant is devoid of O-antigen, which is required for phage adsorption. Intriguingly, while the loss of galU conferred phage resistance, it significantly attenuated PA1r in a mouse infection experiment. Our study revealed a novel phage resistance mechanism via chromosomal DNA deletion in P. aeruginosa.

  20. Prion protein genotype survey confirms low frequency of scrapie-resistant K222 allele in British goat herds

    PubMed Central

    Goldmann, W.; Stewart, P.; Konold, T.; Street, S.; Langeveld, J.; Windl, O.; Ortiz-Pelaez, A.

    2016-01-01

    Scrapie in goats is a transmissible, fatal prion disease, which is endemic in the British goat population. The recent success in defining caprine PRNP gene variants that provide resistance to experimental and natural classical scrapie has prompted the authors to conduct a survey of PRNP genotypes in 10 goat breeds and 52 herds to find goats with the resistant K222 allele. They report here the frequencies in 1236 tested animals of the resistance-associated K222 and several other alleles by breed and herd. Eight animals were found to be heterozygous QK222 goats (0.64 per cent genotype frequency, 95 per cent CI 0.28 to 1.27 per cent) but no homozygous KK222 goats were detected. The K222 allele was found in Saanen, Toggenburg and Anglo-Nubian goats. The fact that only a few goats with the K222 allele have been identified does not preclude the possibility to design and implement successful breeding programmes at national level. PMID:26755614

  1. Prion protein genotype survey confirms low frequency of scrapie-resistant K222 allele in British goat herds.

    PubMed

    Goldmann, W; Marier, E; Stewart, P; Konold, T; Street, S; Langeveld, J; Windl, O; Ortiz-Pelaez, A

    2016-02-13

    Scrapie in goats is a transmissible, fatal prion disease, which is endemic in the British goat population. The recent success in defining caprine PRNP gene variants that provide resistance to experimental and natural classical scrapie has prompted the authors to conduct a survey of PRNP genotypes in 10 goat breeds and 52 herds to find goats with the resistant K222 allele. They report here the frequencies in 1236 tested animals of the resistance-associated K222 and several other alleles by breed and herd. Eight animals were found to be heterozygous QK222 goats (0.64 per cent genotype frequency, 95 per cent CI 0.28 to 1.27 per cent) but no homozygous KK222 goats were detected. The K222 allele was found in Saanen, Toggenburg and Anglo-Nubian goats. The fact that only a few goats with the K222 allele have been identified does not preclude the possibility to design and implement successful breeding programmes at national level.

  2. Lack of association of apoE ε4 allele with insulin resistance.

    PubMed

    Ragogna, Francesca; Lattuada, Guido; Ruotolo, Giacomo; Luzi, Livio; Perseghin, Gianluca

    2012-02-01

    ApoE is a polymorphic protein involved in the metabolism of plasma lipoproteins; the ε4 allele was shown to be associated with coronary and aortic atherosclerosis in age-dependent fashion mediated by unknown mechanisms. This study was undertaken to assess whether the apoE isoforms in humans were associated with normal glucose tolerance and with metabolic and inflammatory risk factors of CVD. ApoE genotype was assessed in 365 individuals. Of those, 309 were studied in the postabsorptive conditions and 142 of them also underwent a 3h-OGTT; 56 additional subjects were studied by means of the insulin clamp in combination with [6,6-2H2] glucose infusion. ApoE genotype frequencies were similar to those previously reported and were not influenced by age and BMI. Fasting plasma glucose, insulin, FFA, the lipid profile, surrogate markers (HOMA-IR, OGTT-derived index) as well as the clamp-derived parameters or insulin sensitivity and insulin secretion were not different by apoE genotypes. Serum adipokines concentrations (leptin, adiponectin, resistin) and markers of inflammation (serum fasting hsCRP and MCP1/CCL2) were also not different by apoE genotypes. In the subgroup of young ε4 carriers which underwent the clamp procedure, a higher fasting endogenous glucose production was detected. ApoE genotype was not associated with insulin resistance or altered insulin secretion, and no abnormalities in the typical circulating endocrine, metabolic, and inflammatory features of the insulin resistance syndrome were detected.

  3. Benzimidazole resistance allele haplotype diversity in United Kingdom isolates of Teladorsagia circumcincta supports a hypothesis of multiple origins of resistance by recurrent mutation.

    PubMed

    Skuce, Philip; Stenhouse, Lindsay; Jackson, Frank; Hypsa, Václav; Gilleard, John

    2010-09-01

    Polymorphisms in the isotype I beta-tubulin gene are important genetic determinants of benzimidazole (BZ) resistance in a number of parasitic nematode species including Teladorsagia circumcincta, a major gastrointestinal nematode of sheep. This study investigates the genetic diversity at this locus in a BZ-resistant isolate of T. circumcincta (MTci5) derived from a sheep farm in the United Kingdom (UK) that was open to animal, and therefore parasite, migration. Pyrosequencing was used to determine the frequency of single nucleotide polymorphisms (SNPs) known to be associated with BZ resistance. This was followed by a combination of single strand conformation polymorphism (SSCP) analysis and nucleotide sequencing to sample allelic diversity in a 276bp fragment immediately surrounding the isotype I beta-tubulin F200Y mutation. The genetic diversity at this locus was extremely high, with seven different haplotypes found to contain the resistant F200Y polymorphism in this single resistant isolate. Genotyping by SSCP interfaced with pyrosequencing demonstrated that the P200(Y) mutation is also present on multiple haplotypes in two other BZ-resistant T. circumcincta isolates from the UK. This contrasts with much lower levels of haplotype diversity in BZ-resistant alleles present in T. circumcincta isolates from French goat farms that are closed to parasite migration. Taken together with our knowledge of T. circumcincta population genetic structure, these results are most consistent with multiple independent origins of resistance and mixing of alleles due to the large amount of livestock movement in the UK.

  4. Allele mining in the pepper gene pool provided new complementation effects between pvr2-eIF4E and pvr6-eIF(iso)4E alleles for resistance to pepper veinal mottle virus.

    PubMed

    Rubio, Manuel; Nicolaï, Maryse; Caranta, Carole; Palloix, Alain

    2009-11-01

    Molecular cloning of recessive resistance genes to potyviruses in a large range of host species identified the eukaryotic translation initiation factor 4E (eIF4E) as an essential determinant in the outcome of potyvirus infection. Resistance results from a few amino acid changes in the eIF4E protein encoded by the recessive resistance allele that disrupt the direct interaction with the potyviral protein VPg. In plants, several loci encode two protein subfamilies, eIF4E and eIF(iso)4E. While most eIF4E-mediated resistance to potyviruses depends on mutations in a single eIF4E protein, simultaneous mutations in eIF4E (corresponding to the pvr2 locus) and eIF(iso)4E (corresponding to the pvr6 locus) are required to prevent pepper veinal mottle virus (PVMV) infection in pepper. We used this model to look for additional alleles at the pvr2-eIF4E locus that result in resistance when combined with the pvr6-eIF(iso)4E resistant allele. Among the 12 pvr2-eIF4E resistance alleles sequenced in the pepper gene pool, three were shown to have a complementary effect with pvr6-eIF(iso)4E for resistance. Two amino acid changes were exclusively shared by these three alleles and were systematically associated with a second amino acid change, suggesting that these substitutions are associated with resistance expression. The availability of new resistant allele combinations increases the possibility for the durable deployment of resistance against this pepper virus which is prevalent in Africa.

  5. Association of BoLA-DRB3 alleles with mastitis resistance and susceptibility in Japanese Holstein cows.

    PubMed

    Yoshida, Tatsuyuki; Furuta, Hiroki; Kondo, Yasuko; Mukoyama, Harutaka

    2012-05-01

    In this study, 714 cows from 26 dairy herds were reclassified as healthy or mastitic cows on the basis of long-term somatic cell count (SCC) in milk. Cows with more than three consecutive lactation records of SCC from the first or second to fifth lactation, were selected, and their BoLA-DRB3 (DRB3) alleles were identified using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Cows with an SCC of < 200 000 cells/mL in all monthly records were classified as healthy (n=91). Cows with an SCC of > 300 000 cells/mL in two consecutive tests or four non-consecutive tests or cows with an SCC of > 500 000 cells/mL in any one test during lactation, regardless of parity, were classified as mastitic (n=201). Mastitic cows (n=153) from another 40 herds were considered to be infected if bacteriological testing revealed mastitis pathogens in milk. Their DRB3 alleles were identified using PCR-sequence-based typing (PCR-SBT). The differences in DRB3 allelic frequencies between healthy cows and cows with various degrees of mastitis were re-investigated. Moreover, the associations of various amino acid motifs in DRB3 alleles with resistance or susceptibility to mastitis pathogens were re-examined. DRB3.2*8(DRB3*1201) and DRB3.2*16(DRB3*1501) alleles were found to be associated with susceptibility, while DRB3.2*22(DRB3*1101), DRB3.2*23(DRB3*2703), and DRB3.2*24(DRB3*0101) alleles were found to be associated with resistance.

  6. The 2-repeat allele of the MAOA gene confers an increased risk for shooting and stabbing behaviors.

    PubMed

    Beaver, Kevin M; Barnes, J C; Boutwell, Brian B

    2014-09-01

    There has been a great deal of research examining the link between a polymorphism in the promoter region of the MAOA gene and antisocial phenotypes. The results of these studies have consistently revealed that low activity MAOA alleles are related to antisocial behaviors for males who were maltreated as children. Recently, though, some evidence has emerged indicating that a rare allele of the MAOA gene-that is, the 2-repeat allele-may have effects on violence that are independent of the environment. The current study builds on this research and examines the association between the 2-repeat allele and shooting and stabbing behaviors in a sample of males drawn from the National Longitudinal Study of Adolescent Health. Analyses revealed that African-American males who carry the 2-repeat allele are significantly more likely than all other genotypes to engage in shooting and stabbing behaviors and to report having multiple shooting and stabbing victims. The limitations of the study are discussed and suggestions for future research are offered.

  7. Academic Conferences: Representative and Resistant Sites for Higher Education Research

    ERIC Educational Resources Information Center

    Henderson, Emily F.

    2015-01-01

    The overarching argument made in this article is twofold. Firstly, academic conferences are posited as sites for higher education research. Secondly, the well-recognised emotional and social processes of conferences are used to make space at the boundaries of higher education research for psychosocial analysis. The article theorises conferences in…

  8. A knowledge-based molecular screen uncovers a broad-spectrum OsSWEET14 resistance allele to bacterial blight from wild rice.

    PubMed

    Hutin, Mathilde; Sabot, François; Ghesquière, Alain; Koebnik, Ralf; Szurek, Boris

    2015-11-01

    Transcription activator-like (TAL) effectors are type III-delivered transcription factors that enhance the virulence of plant pathogenic Xanthomonas species through the activation of host susceptibility (S) genes. TAL effectors recognize their DNA target(s) via a partially degenerate code, whereby modular repeats in the TAL effector bind to nucleotide sequences in the host promoter. Although this knowledge has greatly facilitated our power to identify new S genes, it can also be easily used to screen plant genomes for variations in TAL effector target sequences and to predict for loss-of-function gene candidates in silico. In a proof-of-principle experiment, we screened a germplasm of 169 rice accessions for polymorphism in the promoter of the major bacterial blight susceptibility S gene OsSWEET14, which encodes a sugar transporter targeted by numerous strains of Xanthomonas oryzae pv. oryzae. We identified a single allele with a deletion of 18 bp overlapping with the binding sites targeted by several TAL effectors known to activate the gene. We show that this allele, which we call xa41(t), confers resistance against half of the tested Xoo strains, representative of various geographic origins and genetic lineages, highlighting the selective pressure on the pathogen to accommodate OsSWEET14 polymorphism, and reciprocally the apparent limited possibilities for the host to create variability at this particular S gene. Analysis of xa41(t) conservation across the Oryza genus enabled us to hypothesize scenarios as to its evolutionary history, prior to and during domestication. Our findings demonstrate that resistance through TAL effector-dependent loss of S-gene expression can be greatly fostered upon knowledge-based molecular screening of a large collection of host plants.

  9. Insect Resistance to Bacillus thuringiensis Toxin Cry2Ab Is Conferred by Mutations in an ABC Transporter Subfamily A Protein

    PubMed Central

    Tay, Wee Tek; Mahon, Rod J.; Heckel, David G.; Walsh, Thomas K.; Downes, Sharon; James, William J.; Lee, Sui-Fai; Reineke, Annette; Williams, Adam K.; Gordon, Karl H. J.

    2015-01-01

    The use of conventional chemical insecticides and bacterial toxins to control lepidopteran pests of global agriculture has imposed significant selection pressure leading to the rapid evolution of insecticide resistance. Transgenic crops (e.g., cotton) expressing the Bt Cry toxins are now used world wide to control these pests, including the highly polyphagous and invasive cotton bollworm Helicoverpa armigera. Since 2004, the Cry2Ab toxin has become widely used for controlling H. armigera, often used in combination with Cry1Ac to delay resistance evolution. Isolation of H. armigera and H. punctigera individuals heterozygous for Cry2Ab resistance in 2002 and 2004, respectively, allowed aspects of Cry2Ab resistance (level, fitness costs, genetic dominance, complementation tests) to be characterised in both species. However, the gene identity and genetic changes conferring this resistance were unknown, as was the detailed Cry2Ab mode of action. No cross-resistance to Cry1Ac was observed in mutant lines. Biphasic linkage analysis of a Cry2Ab-resistant H. armigera family followed by exon-primed intron-crossing (EPIC) marker mapping and candidate gene sequencing identified three independent resistance-associated INDEL mutations in an ATP-Binding Cassette (ABC) transporter gene we named HaABCA2. A deletion mutation was also identified in the H. punctigera homolog from the resistant line. All mutations truncate the ABCA2 protein. Isolation of further Cry2Ab resistance alleles in the same gene from field H. armigera populations indicates unequal resistance allele frequencies and the potential for Bt resistance evolution. Identification of the gene involved in resistance as an ABC transporter of the A subfamily adds to the body of evidence on the crucial role this gene family plays in the mode of action of the Bt Cry toxins. The structural differences between the ABCA2, and that of the C subfamily required for Cry1Ac toxicity, indicate differences in the detailed mode

  10. Recent Rapid Rise of a Permethrin Knock Down Resistance Allele in Aedes aegypti in México

    PubMed Central

    García, Gustavo Ponce; Flores, Adriana E.; Fernández-Salas, Ildefonso; Saavedra-Rodríguez, Karla; Reyes-Solis, Guadalupe; Lozano-Fuentes, Saul; Guillermo Bond, J.; Casas-Martínez, Mauricio; Ramsey, Janine M.; García-Rejón, Julián; Domínguez-Galera, Marco; Ranson, Hilary; Hemingway, Janet; Eisen, Lars; Black, William C.

    2009-01-01

    Background Aedes aegypti, the ‘yellow fever mosquito’, is the primary vector to humans of dengue and yellow fever flaviviruses (DENV, YFV), and is a known vector of the chikungunya alphavirus (CV). Because vaccines are not yet available for DENV or CV or are inadequately distributed in developing countries (YFV), management of Ae. aegypti remains the primary option to prevent and control outbreaks of the diseases caused by these arboviruses. Permethrin is one of the most widely used active ingredients in insecticides for suppression of adult Ae. aegypti. In 2007, we documented a replacement mutation in codon 1,016 of the voltage-gated sodium channel gene (para) of Ae. aegypti that encodes an isoleucine rather than a valine and confers resistance to permethrin. Ile1,016 segregates as a recessive allele conferring knockdown resistance to homozygous mosquitoes at 5–10 µg of permethrin in bottle bioassays. Methods and Findings A total of 81 field collections containing 3,951 Ae. aegypti were made throughout México from 1996 to 2009. These mosquitoes were analyzed for the frequency of the Ile1,016 mutation using a melting-curve PCR assay. Dramatic increases in frequencies of Ile1,016 were recorded from the late 1990's to 2006–2009 in several states including Nuevo León in the north, Veracruz on the central Atlantic coast, and Yucatán, Quintana Roo and Chiapas in the south. From 1996 to 2000, the overall frequency of Ile1,016 was 0.04% (95% confidence interval (CI95) = 0.12%; n = 1,359 mosquitoes examined). The earliest detection of Ile1,016 was in Nuevo Laredo on the U.S. border in 1997. By 2003–2004 the overall frequency of Ile1,016 had increased ∼100-fold to 2.7% (±0.80% CI95; n = 808). When checked again in 2006, the frequency had increased slightly to 3.9% (±1.15% CI95; n = 473). This was followed in 2007–2009 by a sudden jump in Ile1,016 frequency to 33.2% (±1.99% CI95; n = 1,074 mosquitoes). There was spatial heterogeneity

  11. Characterization of Klebsiella sp. strain 10982, a colonizer of humans that contains novel antibiotic resistance alleles and exhibits genetic similarities to plant and clinical Klebsiella isolates.

    PubMed

    Hazen, Tracy H; Zhao, LiCheng; Sahl, Jason W; Robinson, Gwen; Harris, Anthony D; Rasko, David A; Johnson, J Kristie

    2014-01-01

    A unique Klebsiella species strain, 10982, was cultured from a perianal swab specimen obtained from a patient in the University of Maryland Medical Center intensive care unit. Klebsiella sp. 10982 possesses a large IncA/C multidrug resistance plasmid encoding a novel FOX AmpC β-lactamase designated FOX-10. A novel variant of the LEN β-lactamase was also identified. Genome sequencing and bioinformatic analysis demonstrated that this isolate contains genes associated with nitrogen fixation, allantoin metabolism, and citrate fermentation. These three gene regions are typically present in either Klebsiella pneumoniae clinical isolates or Klebsiella nitrogen-fixing endophytes but usually not in the same organism. Phylogenomic analysis of Klebsiella sp. 10982 and sequenced Klebsiella genomes demonstrated that Klebsiella sp. 10982 is present on a branch that is located intermediate between the genomes of nitrogen-fixing endophytes and K. pneumoniae clinical isolates. Metabolic features identified in the genome of Klebsiella sp. 10982 distinguish this isolate from other Klebsiella clinical isolates. These features include the nitrogen fixation (nif) gene cluster, which is typically present in endophytic Klebsiella isolates and is absent from Klebsiella clinical isolates. Additionally, the Klebsiella sp. 10982 genome contains genes associated with allantoin metabolism, which have been detected primarily in K. pneumoniae isolates from liver abscesses. Comparative genomic analysis of Klebsiella sp. 10982 demonstrated that this organism has acquired genes conferring new metabolic strategies and novel antibiotic resistance alleles, both of which may enhance its ability to colonize the human body.

  12. Cancer cell mitochondria confer apoptosis resistance and promote metastasis.

    PubMed

    Kulawiec, Mariola; Owens, Kjerstin M; Singh, Keshav K

    2009-07-01

    Mutations in mtDNA are found in most cancers. In this study, we studied the role of cancer cell mutant mtDNA in tumorigenesis. We sequenced the entire mitochondrial genome of three different breast cancer cell lines and found that all three, MCF7, MDA-MB-231 and MDA-MB-435, contained mutations in mtDNA. MDA-MB-435 cells contained a mutation in the tRNA(Leu(CUN)) gene known to be involved in pathogenesis of mitochondrial diseases. We generated a mutant cybrid (cytoplasmic hybrid) by repopulating the recipient rho(0) (completely devoid of mtDNA) cells with donor mtDNA derived from an enucleated MDA-MB-435 breast cancer cell line. An isogenic wild-type cybrid was produced by transfer of normal mtDNA from a healthy donor. When compared to the wild type, we found that mutant mtDNA increases mitochondrial membrane potential. However, this increase in mitochondrial membrane potential was not associated with increase in reactive oxygen species (ROS) production. MtDNA mutations conferred resistance to apoptosis triggered by etoposide. Our study also revealed that mutations in mtDNA increase metastatic potential. Using a tail-vein model of metastasis in a mouse model, we show that the mutant cybrid metastatizes to the lungs and forms macrometastic foci. Additionally we found that mutations in mtDNA constitutively activate the PI3/Akt pathway that contributes to increased metastatis. Together our study demonstrates that mutant mtDNA promotes apoptotic resistance and metastasis in a mouse model.

  13. Facultative bacterial symbionts in aphids confer resistance to parasitic wasps

    PubMed Central

    Oliver, Kerry M.; Russell, Jacob A.; Moran, Nancy A.; Hunter, Martha S.

    2003-01-01

    Symbiotic relationships between animals and microorganisms are common in nature, yet the factors controlling the abundance and distributions of symbionts are mostly unknown. Aphids have an obligate association with the bacterium Buchnera aphidicola (the primary symbiont) that has been shown to contribute directly to aphid fitness. In addition, aphids sometimes harbor other vertically transmitted bacteria (secondary symbionts), for which few benefits of infection have been previously documented. We carried out experiments to determine the consequences of these facultative symbioses in Acyrthosiphon pisum (the pea aphid) for vulnerability of the aphid host to a hymenopteran parasitoid, Aphidius ervi, a major natural enemy in field populations. Our results show that, in a controlled genetic background, infection confers resistance to parasitoid attack by causing high mortality of developing parasitoid larvae. Compared with uninfected controls, experimentally infected aphids were as likely to be attacked by ovipositing parasitoids but less likely to support parasitoid development. This strong interaction between a symbiotic bacterium and a host natural enemy provides a mechanism for the persistence and spread of symbiotic bacteria. PMID:12563031

  14. Independent origins of loss-of-function mutations conferring oxamniquine resistance in a Brazilian schistosome population.

    PubMed

    Chevalier, Frédéric D; Le Clec'h, Winka; Eng, Nina; Rugel, Anastasia R; Assis, Rafael Ramiro de; Oliveira, Guilherme; Holloway, Stephen P; Cao, Xiaohang; Hart, P John; LoVerde, Philip T; Anderson, Timothy J C

    2016-06-01

    Molecular surveillance provides a powerful approach to monitoring the resistance status of parasite populations in the field and for understanding resistance evolution. Oxamniquine was used to treat Brazilian schistosomiasis patients (mid-1970s to mid-2000s) and several cases of parasite infections resistant to treatment were recorded. The gene underlying resistance (SmSULT-OR) encodes a sulfotransferase required for intracellular drug activation. Resistance has a recessive basis and occurs when both SmSULT-OR alleles encode for defective proteins. Here we examine SmSULT-OR sequence variation in a natural schistosome population in Brazil ∼40years after the first use of this drug. We sequenced SmSULT-OR from 189 individual miracidia (1-11 per patient) recovered from 49 patients, and tested proteins expressed from putative resistance alleles for their ability to activate oxamniquine. We found nine mutations (four non-synonymous single nucleotide polymorphisms, three non-coding single nucleotide polymorphisms and two indels). Both mutations (p.E142del and p.C35R) identified previously were recovered in this field population. We also found two additional mutations (a splice site variant and 1bp coding insertion) predicted to encode non-functional truncated proteins. Two additional substitutions (p.G206V, p.N215Y) tested had no impact on oxamniquine activation. Three results are of particular interest: (i) we recovered the p.E142del mutation from the field: this same deletion is responsible for resistance in an oxamniquine selected laboratory parasite population; (ii) frequencies of resistance alleles are extremely low (0.27-0.8%), perhaps due to fitness costs associated with carriage of these alleles; (iii) that four independent resistant alleles were found is consistent with the idea that multiple mutations can generate loss-of-function alleles.

  15. Involvement of HLA class I alleles in natural killer (NK) cell-specific functions: expression of HLA-Cw3 confers selective protection from lysis by alloreactive NK clones displaying a defined specificity (specificity 2)

    PubMed Central

    1992-01-01

    This study was designed to identify the target molecules of the natural killer (NK) cell-mediated recognition of normal allogeneic target cells. As previously shown, the gene(s) governing the first NK-defined allospecificity (specificity 1) were found to be localized in the major histocompatibility complex region between BF gene and HLA-A. In addition, the analysis of a previously described family revealed that a donor (donor 81) was heterozygous for three distinct NK-defined allospecificities (specificities 1, 2, and 5). HLA variants were derived from the B-Epstein-Barr virus cell line of donor 81 by gamma irradiation followed by negative selection using monoclonal antibodies specific for the appropriate HLA allele. Several variants were derived that lacked one or more class I antigen expressions. These variants were analyzed for the susceptibility to lysis by NK clones recognizing different allospecificities. The loss of HLA-A did not modify the phenotype (i.e., "resistance to lysis"). On the other hand, a variant lacking expression of all class I antigens became susceptible to lysis by all alloreactive clones. Variants characterized by the selective loss of class I antigens coded for by the maternal chromosome became susceptible to lysis by anti-2-specific clones. Conversely, variants selectively lacking class I antigens coded for by paternal chromosome became susceptible to lysis by anti-1 and anti-5 clones (but not by anti-2 clones). Since the Cw3 allele was lost in the variant that acquired susceptibility to lysis by anti-2 clones and, in informative families, it was found to cosegregate with the character "resistance to lysis" by anti-2 clones, we analyzed whether Cw3 could represent the element conferring selective resistance to lysis by anti-2 clones. To this end, murine P815 cells transfected with HLA Cw3 (or with other HLA class I genes) were used as target cells in a cytolytic assay in which effector cells were represented by alloreactive NK clones

  16. High Susceptibility to Cry1Ac and Low Resistance Allele Frequency Reduce the Risk of Resistance of Helicoverpa armigera to Bt Soybean in Brazil

    PubMed Central

    Bacalhau, Fabiana B.; Amado, Douglas; Carvalho, Renato A.; Martinelli, Samuel; Head, Graham P.; Omoto, Celso

    2016-01-01

    The Old World bollworm, Helicoverpa armigera (Hübner), was recently introduced into Brazil, where it has caused extensive damage to cotton and soybean crops. MON 87701 × MON 89788 soybean, which expresses the Bt protein Cry1Ac, was recently deployed in Brazil, providing high levels of control against H. armigera. To assess the risk of resistance to the Cry1Ac protein expressed by MON 87701 × MON 89788 soybean in Brazil, we conducted studies to evaluate the baseline susceptibility of H. armigera to Cry1Ac, in planta efficacy including the assessment of the high-dose criterion, and the initial resistance allele frequency based on an F2 screen. The mean Cry1Ac lethal concentration (LC50) ranged from 0.11 to 1.82 μg·mL−1 of diet among all H. armigera field populations collected from crop seasons 2013/14 to 2014/15, which indicated about 16.5-fold variation. MON 87701 × MON 89788 soybean exhibited a high level of efficacy against H. armigera and most likely met the high dose criterion against this target species in leaf tissue dilution bioassays up to 50 times. A total of 212 F2 family lines of H. armigera were established from field collections sampled from seven locations across Brazil and were screened for the presence of MON 87701 × MON 89788 soybean resistance alleles. None of the 212 families survived on MON 87701 × MON 89788 soybean leaf tissue (estimated allele frequency = 0.0011). The responses of H. armigera to Cry1Ac protein, high susceptibility to MON 87701 × MON 89788 soybean, and low frequency of resistance alleles across the main soybean-producing regions support the assumptions of a high-dose/refuge strategy. However, maintenance of reasonable compliance with the refuge recommendation will be essential to delay the evolution of resistance in H. armigera to MON 87701 × MON 89788 soybean in Brazil. PMID:27532632

  17. High Susceptibility to Cry1Ac and Low Resistance Allele Frequency Reduce the Risk of Resistance of Helicoverpa armigers to Bt Soybean in Brazil.

    PubMed

    Dourado, Patrick M; Bacalhau, Fabiana B; Amado, Douglas; Carvalho, Renato A; Martinelli, Samuel; Head, Graham P; Omoto, Celso

    2016-01-01

    The Old World bollworm, Helicoverpa armigera (Hübner), was recently introduced into Brazil, where it has caused extensive damage to cotton and soybean crops. MON 87701 × MON 89788 soybean, which expresses the Bt protein Cry1Ac, was recently deployed in Brazil, providing high levels of control against H. armigera. To assess the risk of resistance to the Cry1Ac protein expressed by MON 87701 × MON 89788 soybean in Brazil, we conducted studies to evaluate the baseline susceptibility of H. armigera to Cry1Ac, in planta efficacy including the assessment of the high-dose criterion, and the initial resistance allele frequency based on an F2 screen. The mean Cry1Ac lethal concentration (LC50) ranged from 0.11 to 1.82 μg·mL-1 of diet among all H. armigera field populations collected from crop seasons 2013/14 to 2014/15, which indicated about 16.5-fold variation. MON 87701 × MON 89788 soybean exhibited a high level of efficacy against H. armigera and most likely met the high dose criterion against this target species in leaf tissue dilution bioassays up to 50 times. A total of 212 F2 family lines of H. armigera were established from field collections sampled from seven locations across Brazil and were screened for the presence of MON 87701 × MON 89788 soybean resistance alleles. None of the 212 families survived on MON 87701 × MON 89788 soybean leaf tissue (estimated allele frequency = 0.0011). The responses of H. armigera to Cry1Ac protein, high susceptibility to MON 87701 × MON 89788 soybean, and low frequency of resistance alleles across the main soybean-producing regions support the assumptions of a high-dose/refuge strategy. However, maintenance of reasonable compliance with the refuge recommendation will be essential to delay the evolution of resistance in H. armigera to MON 87701 × MON 89788 soybean in Brazil.

  18. The variant allele of the rs188140481 polymorphism confers a moderate increase in the risk of prostate cancer in Polish men.

    PubMed

    Antczak, Andrzej; Wokołorczyk, Dominika; Kluźniak, Wojciech; Kashyap, Aniruddh; Jakubowska, Anna; Gronwald, Jacek; Huzarski, Tomasz; Byrski, Tomasz; Dębniak, Tadeusz; Masojć, Bartłomiej; Górski, Bohdan; Gromowski, Tomasz; Gołąb, Adam; Sikorski, Andrzej; Słojewski, Marcin; Gliniewicz, Bartłomiej; Borkowski, Tomasz; Borkowski, Andrzej; Przybyła, Jacek; Sosnowski, Marek; Małkiewicz, Bartosz; Zdrojowy, Romuald; Sikorska-Radek, Paulina; Matych, Józef; Wilkosz, Jacek; Różański, Waldemar; Kiś, Jacek; Bar, Krzysztof; Janiszewska, Hanna; Stawicka, Małgorzata; Milecki, Piotr; Lubiński, Jan; Narod, Steven A; Cybulski, Cezary

    2015-03-01

    A number of single nucleotide polymorphisms (SNPs) in the human genome have been associated with increased risk of prostate cancer. Recently, a single SNP in the region of chromosome 8q24 (rs188140481) has been associated with a three-fold increased risk of prostate cancer in Europe and North America. To establish whether rs188140481 is associated with the risk of prostate cancer in Poland, we genotyped 3467 men with prostate cancer and 1958 controls. The A allele of rs188140481 was detected in 44 of 3467 (1.3%) men with prostate cancer and in seven of 1958 (0.4%) controls (odds ratio=3.6; 95% confidence interval 1.6-7.9; P=0.0006). The allele was present in eight of 390 (2.1%) men with familial prostate cancer (odds ratio=5.8; 95% confidence interval 2.1-16.2; P=0.001). A positive family history of cancers at sites other than the prostate was observed in 27% of men who carried the rs188140481 risk allele and in 44% of noncarriers (P=0.04). No cancer at a site other than the prostate was more common in first-degree or second-degree relatives of carriers of the rs188140481 risk allele than relatives of noncarriers. The rs188140481 polymorphism in the 8q24 region confers a moderate increase in the risk of prostate cancer in Polish men. The SNP does not appear to be associated with susceptibility to cancers of other types.

  19. The allelic variant of LAR gene promoter -127 bp T-->A is associated with reduced risk of obesity and other features related to insulin resistance.

    PubMed

    Miscio, Giuseppe; Tassi, Vittorio; Coco, Angelo; Soccio, Teresa; Di Paola, Rosa; Prudente, Sabrina; Baratta, Roberto; Frittitta, Lucia; Ludovico, Ornella; Padovano, Libera; Dallapiccola, Bruno; Di Mario, Umberto; De Cosmo, Salvatore; Trischitta, Vincenzo

    2004-07-01

    Insulin resistance, which is pathogenic for type 2 diabetes (T2D), is under the control of largely unknown genetic determinants. LAR, a protein-tyrosine phosphatase which inhibits insulin signalling, is overexpressed in animal and human models of insulin resistance. We studied the entire sequence of the LAR gene by SSCP analysis and automatic DNA sequencing, with the aim of verifying whether its sequence variants might be associated with insulin resistance. In the 276 bp sequence upstream of the transcriptional start site (i.e. a region we have identified as having basal promoter activity) a -127 bp T-->A SNP (5% frequency) was associated with lower body mass index (BMI) ( P=0.03), waist circumference ( P=0.01), blood pressure ( P=0.01) and urinary albumin/creatinine ratio ( P=0.04) in 589 non-diabetic unrelated individuals from the Gargano region (central east coast of Italy). To quantify the risk for a high body weight conferred by the -127 T-->A SNP, the whole cohort was divided into tertiles according to the individual BMI. The risk of belonging to the heavier tertile, as compared to the leaner one, was reduced by approximately 60%. In a population from East Sicily ( n=307), T/A genotype carriers ( n=13) showed lower triglyceride levels ( P=0.04) and higher insulin sensitivity as indicated by lower plasma glucose ( P=0.03) and serum insulin ( P=0.006) during oral glucose tolerance testing (OGTT). Promoter activity, studied by cDNA transfection experiments, was similar for the A and T alleles. In conclusion, a genetic variant of the LAR gene promoter is consistently associated with features of insulin resistance in two different Caucasian populations. Although the biological relevance of this variant has yet to be determined, this finding underlines the potential importance of the LAR gene in dysregulation of insulin sensitivity and related disorders.

  20. Rifampin Resistance rpoB Alleles or Multicopy Thioredoxin/Thioredoxin Reductase Suppresses the Lethality of Disruption of the Global Stress Regulator spx in Staphylococcus aureus

    PubMed Central

    Villanueva, Maite; Jousselin, Ambre; Baek, Kristoffer T.; Prados, Julien; Andrey, Diego O.; Renzoni, Adriana; Ingmer, Hanne; Frees, Dorte

    2016-01-01

    genetic regulatory circuits and discovering promising new targets for therapeutic intervention. In this study, we discovered that Spx, an RNA polymerase-interacting stress regulator implicated in many stress responses in S. aureus, including responses to oxidative and cell wall antibiotics, is essential. We describe two mechanisms that suppress the lethality of spx disruption. One mechanism highlights how only certain rifampin resistance-encoding alleles of RpoB confer new properties on RNA polymerase, with important mechanistic implications. We describe additional stress conditions where the loss of spx is deleterious, thereby highlighting Spx as a multifaceted regulator and attractive drug discovery target. PMID:27432833

  1. Cutting Edge: Resistance to Bacillus anthracis Infection Mediated by a Lethal Toxin Sensitive Allele of Nalp1b/Nlrp1b

    DTIC Science & Technology

    2010-01-01

    Nalp1b/Nlrp1b Lethal Toxin Sensitive Allele of Infection Mediated by aanthracis BacillusCutting Edge: Resistance to http://www.jimmunol.org/cgi/content...COVERED - 4. TITLE AND SUBTITLE Cutting edge: resistance to Bacillus anthracis infection mediated by a lethal toxin -sensitive allele of Nalp1b...Bacillus anthracis is associated with the production of lethal toxin (LT), which activates the murine Nalp1b/Nlrp1b inflammasome and induces caspase

  2. Mutations in the Plasmodium falciparum Cyclic Amine Resistance Locus (PfCARL) Confer Multidrug Resistance

    PubMed Central

    LaMonte, Gregory; Lim, Michelle Yi-Xiu; Wree, Melanie; Reimer, Christin; Nachon, Marie; Corey, Victoria; Gedeck, Peter; Plouffe, David; Du, Alan; Figueroa, Nelissa; Yeung, Bryan; Winzeler, Elizabeth A.

    2016-01-01

    ABSTRACT Mutations in the Plasmodium falciparum cyclic amine resistance locus (PfCARL) are associated with parasite resistance to the imidazolopiperazines, a potent class of novel antimalarial compounds that display both prophylactic and transmission-blocking activity, in addition to activity against blood-stage parasites. Here, we show that pfcarl encodes a protein, with a predicted molecular weight of 153 kDa, that localizes to the cis-Golgi apparatus of the parasite in both asexual and sexual blood stages. Utilizing clustered regularly interspaced short palindromic repeat (CRISPR)-mediated gene introduction of 5 variants (L830V, S1076N/I, V1103L, and I1139K), we demonstrate that mutations in pfcarl are sufficient to generate resistance against the imidazolopiperazines in both asexual and sexual blood-stage parasites. We further determined that the mutant PfCARL protein confers resistance to several structurally unrelated compounds. These data suggest that PfCARL modulates the levels of small-molecule inhibitors that affect Golgi-related processes, such as protein sorting or membrane trafficking, and is therefore an important mechanism of resistance in malaria parasites. PMID:27381290

  3. A novel blast resistance gene, Pi54rh cloned from wild species of rice, Oryza rhizomatis confers broad spectrum resistance to Magnaporthe oryzae.

    PubMed

    Das, Alok; Soubam, D; Singh, P K; Thakur, S; Singh, N K; Sharma, T R

    2012-06-01

    The dominant rice blast resistance gene, Pi54 confers resistance to Magnaporthe oryzae in different parts of India. In our effort to identify more effective forms of this gene, we isolated an orthologue of Pi54 named as Pi54rh from the blast-resistant wild species of rice, Oryza rhizomatis, using allele mining approach and validated by complementation. The Pi54rh belongs to CC-NBS-LRR family of disease resistance genes with a unique Zinc finger (C(3)H type) domain. The 1,447 bp Pi54rh transcript comprises of 101 bp 5'-UTR, 1,083 bp coding region and 263 bp 3'-UTR, driven by pathogen inducible promoter. We showed the extracellular localization of Pi54rh protein and the presence of glycosylation, myristoylation and phosphorylation sites which implicates its role in signal transduction process. This is in contrast to other blast resistance genes that are predicted to be intracellular NBS-LRR-type resistance proteins. The Pi54rh was found to express constitutively at basal level in the leaves, but upregulates 3.8-fold at 96 h post-inoculation with the pathogen. Functional validation of cloned Pi54rh gene using complementation test showed high degree of resistance to seven isolates of M. oryzae collected from different geographical locations of India. In this study, for the first time, we demonstrated that a rice blast resistance gene Pi54rh cloned from wild species of rice provides broad spectrum resistance to M. oryzae hence can be used in rice improvement breeding programme.

  4. Molecular mapping and validation of a major QTL conferring resistance to a defoliating isolate of verticillium wilt in cotton (Gossypium hirsutum L.).

    PubMed

    Zhang, Xingju; Yuan, Yanchao; Wei, Ze; Guo, Xian; Guo, Yuping; Zhang, Suqing; Zhao, Junsheng; Zhang, Guihua; Song, Xianliang; Sun, Xuezhen

    2014-01-01

    Verticillium wilt (VW) caused by Verticillium dahliae Kleb is one of the most destructive diseases of cotton. Development and use of a VW resistant variety is the most practical and effective way to manage this disease. Identification of highly resistant genes/QTL and the underlining genetic architecture is a prerequisite for developing a VW resistant variety. A major QTL qVW-c6-1 conferring resistance to the defoliating isolate V991 was identified on chromosome 6 in LHB22×JM11 F2∶3 population inoculated and grown in a greenhouse. This QTL was further validated in the LHB22×NNG F2∶3 population that was evaluated in an artificial disease nursery of V991 for two years and in its subsequent F4 population grown in a field severely infested by V991. The allele conferring resistance within the QTL qVW-c6-1 region originated from parent LHB22 and could explain 23.1-27.1% of phenotypic variation. Another resistance QTL qVW-c21-1 originated from the susceptible parent JM11 was mapped on chromosome 21, explaining 14.44% of phenotypic variation. The resistance QTL reported herein provides a useful tool for breeding a cotton variety with enhanced resistance to VW.

  5. Molecular Mapping and Validation of a Major QTL Conferring Resistance to a Defoliating Isolate of Verticillium Wilt in Cotton (Gossypium hirsutum L.)

    PubMed Central

    Wei, Ze; Guo, Xian; Guo, Yuping; Zhang, Suqing; Zhao, Junsheng; Zhang, Guihua; Song, Xianliang; Sun, Xuezhen

    2014-01-01

    Verticillium wilt (VW) caused by Verticillium dahliae Kleb is one of the most destructive diseases of cotton. Development and use of a VW resistant variety is the most practical and effective way to manage this disease. Identification of highly resistant genes/QTL and the underlining genetic architecture is a prerequisite for developing a VW resistant variety. A major QTL qVW-c6-1 conferring resistance to the defoliating isolate V991 was identified on chromosome 6 in LHB22×JM11 F2∶3 population inoculated and grown in a greenhouse. This QTL was further validated in the LHB22×NNG F2∶3 population that was evaluated in an artificial disease nursery of V991 for two years and in its subsequent F4 population grown in a field severely infested by V991. The allele conferring resistance within the QTL qVW-c6-1 region originated from parent LHB22 and could explain 23.1–27.1% of phenotypic variation. Another resistance QTL qVW-c21-1 originated from the susceptible parent JM11 was mapped on chromosome 21, explaining 14.44% of phenotypic variation. The resistance QTL reported herein provides a useful tool for breeding a cotton variety with enhanced resistance to VW. PMID:24781706

  6. Allele-specific conventional reverse-transcription polymerase chain reaction as a screening assay for discriminating influenza a H1N1 (H275Y) oseltamivir-resistant and wild-type viruses.

    PubMed

    Ngai, Karry L K; Lam, Wai-Yip; Lee, Nelson; Leung, Ting Fan; Hui, David S C; Chan, Paul K S

    2010-08-01

    In early 2008, a sudden increase in oseltamivir (Tamiflu)-resistant influenza A H1N1 viruses was reported from several European countries. This resistant virus has spread globally and accounted for more than 95% of H1N1 viruses isolated in the following influenza season. A continuous close monitoring on the prevalence of this resistant virus is necessary to rationalize the choice of antiviral agents. The resistance of this novel strain to oseltamivir is conferred by an amino acid substitution from histidine to tyrosine at position 275 (H275Y) of the neuraminidase protein. This study developed and evaluated allele-specific conventional reverse-transcription polymerase chain reaction (cRT-PCR) assays to provide a simple, rapid, and low-cost option for discriminating oseltamivir-resistant influenza A H1N1 (H275Y) mutant from wild-type viruses. The evaluation was based on 90 nasopharyngeal aspirate specimens collected before, during the initial phase and at the peak of emergence of resistance. Thirty-six (40%) of these specimens were H275Y mutant, whereas the other 54 (60%) were wild-type viruses as confirmed by sequencing of the neuraminidase gene. When applied directly on the 90 nasopharyngeal aspirate specimens, the allele-specific cRT-PCR assays achieved an unequivocal discrimination for 82 (91%) specimens. Further improvement in performance is expected when applied to cell culture isolates with a higher viral titer. These allele-specific cRT-PCR assays can be a simple, low-cost option for large-scale screening of influenza isolates.

  7. Quantitative Sequencing for the Determination of Kdr-type Resistance Allele (V419L, L925I, I936F) Frequencies in Common Bed Bug (Hemiptera: Cimicidae) Populations Collected from Israel.

    PubMed

    Palenchar, Daniel J; Gellatly, Kyle J; Yoon, Kyong Sup; Mumcuoglu, Kosta Y; Shalom, Uri; Clark, J Marshall

    2015-09-01

    Human bed bug infestations have dramatically increased worldwide since the mid-1990s. A similar phenomenon was also observed in Israel since 2005, when infestations were reported from all over the country. Two single nucleotide polymorphisms (V419L and L925I) in the bed bug voltage-sensitive sodium channel confer kdr-type resistance to pyrethroids. Using quantitative sequencing (QS), the resistance allele frequencies of Israeli bed bug populations from across the country were determined. Genomic DNA was extracted from samples of 12 populations of bed bugs collected from Israel and DNA fragments containing the V419L or L925I and I936F mutations sites were PCR amplified. The PCR products were analyzed by QS and the nucleotide signal ratios calculated and used to predict the resistance allele frequencies of the unknown populations. Results of the genetic analysis show that resistant nucleotide signals are highly correlated to resistance allele frequencies for both mutations. Ten of the 12 tested populations had 100% of the L925I mutation and 0% of the V419L mutation. One population was heterogeneous for the L925I mutation and had 0% of the V419L mutation and another population was heterogeneous for the V419L mutation and had 100% of the L925I mutation. I936F occurred only at low levels. These results indicate that bed bugs in Israel are genetically resistant to pyrethroids. Thus, pyrethroids should only be used for bed bug management with caution using effective application and careful monitoring procedures. Additionally, new and novel-acting insecticides and nonchemical means of controlling bed bugs should be explored.

  8. Allelic variants of the Pseudomonas syringae type III effector HopZ1 are differentially recognized by plant resistance systems.

    PubMed

    Zhou, Huanbin; Morgan, Robyn L; Guttman, David S; Ma, Wenbo

    2009-02-01

    The bacterial plant pathogen Pseudomonas syringae depends on the type III secretion system and type III-secreted effectors to cause disease in plants. HopZ is a diverse family of type III effectors widely distributed in P. syringae isolates. Among the HopZ homologs, HopZ1 is ancient to P. syringae and has been shown to be under strong positive selection driven by plant resistance-imposed selective pressure. Here, we characterized the virulence and avirulence functions of the three HopZ1 alleles in soybean and Nicotiana benthamiana. In soybean, HopZ1 alleles have distinct functions: HopZ1a triggers defense response, HopZ1b promotes bacterial growth, and HopZ1c has no observable effect. In N. benthamiana, HopZ1a and HopZ1b both induce plant defense responses. However, they appear to trigger different resistance pathways, evidenced by two major differences between HopZ1a- and HopZ1b-triggered hypersensitive response (HR): i) the putative N-acylation sites had no effect on HopZ1a-triggered cell death, whereas it greatly enhanced HopZ1b-triggered cell death; and ii) the HopZ1b-triggered HR, but not the HopZ1a-triggered HR, was suppressed by another HopZ homolog, HopZ3. We previously demonstrated that HopZ1a most resembled the ancestral allelic form of HopZ1; therefore, this new evidence suggested that differentiated resistance systems have evolved in plant hosts to adapt to HopZ1 diversification in P. syringae.

  9. Epigenetic regulation of antagonistic receptors confers rice blast resistance with yield balance.

    PubMed

    Deng, Yiwen; Zhai, Keran; Xie, Zhen; Yang, Dongyong; Zhu, Xudong; Liu, Junzhong; Wang, Xin; Qin, Peng; Yang, Yuanzhu; Zhang, Guomin; Li, Qun; Zhang, Jianfu; Wu, Shuangqing; Milazzo, Joëlle; Mao, Bizeng; Wang, Ertao; Xie, Huaan; Tharreau, Didier; He, Zuhua

    2017-03-03

    Crop breeding aims to balance disease resistance with yield; however, single resistance (R) genes can lead to resistance breakdown, and R gene pyramiding may affect growth fitness. Here we report that the rice Pigm locus contains a cluster of genes encoding nucleotide-binding leucine-rich repeat (NLR) receptors that confer durable resistance to the fungus Magnaporthe oryzae without yield penalty. Among these NLR receptors, PigmR confers broad-spectrum resistance, whereas PigmS competitively attenuates PigmR homodimerization to suppress resistance. PigmS expression, and thus PigmR-mediated resistance, are subjected to tight epigenetic regulation. PigmS increases seed production to counteract the yield cost induced by PigmR Therefore, our study reveals a mechanism balancing high disease resistance and yield through epigenetic regulation of paired antagonistic NLR receptors, providing a tool to develop elite crop varieties.

  10. Distribution of Voltage-Gated Sodium Channel (Nav) Alleles among the Aedes aegypti Populations In Central Java Province and Its Association with Resistance to Pyrethroid Insecticides.

    PubMed

    Sayono, Sayono; Hidayati, Anggie Puspa Nur; Fahri, Sukmal; Sumanto, Didik; Dharmana, Edi; Hadisaputro, Suharyo; Asih, Puji Budi Setia; Syafruddin, Din

    2016-01-01

    The emergence of insecticide resistant Aedes aegypti mosquitoes has hampered dengue control efforts. WHO susceptibility tests, using several pyrethroid compounds, were conducted on Ae. aegypti larvae that were collected and raised to adulthood from Semarang, Surakarta, Kudus and Jepara in Java. The AaNaV gene fragment encompassing kdr polymorphic sites from both susceptible and resistant mosquitoes was amplified, and polymorphisms were associated with the resistant phenotype. The insecticide susceptibility tests demonstrated Ae, aegypti resistance to the pyrethroids, with mortality rates ranging from 1.6%-15.2%. Three non-synonymous polymorphisms (S989P, V1016G and F1534C) and one synonymous polymorphism (codon 982) were detected in the AaNaV gene. Eight AaNaV alleles were observed in specimens from Central Java. Allele 3 (SGF) and allele 7 (PGF) represent the most common alleles found and demonstrated strong associations with resistance to pyrethroids (OR = 2.75, CI: 0.97-7.8 and OR = 7.37, CI: 2.4-22.5, respectively). This is the first report of 8 Ae. aegypti AaNaV alleles, and it indicates the development of resistance in Ae. aegypti in response to pyrethroid insecticide-based selective pressure. These findings strongly suggest the need for an appropriate integrated use of insecticides in the region. The 989P, 1016G and 1534C polymorphisms in the AaNaV gene are potentially valuable molecular markers for pyrethroid insecticide resistance monitoring.

  11. A recombined allele of the lipase gene CEL and its pseudogene CELP confers susceptibility to chronic pancreatitis.

    PubMed

    Fjeld, Karianne; Weiss, Frank Ulrich; Lasher, Denise; Rosendahl, Jonas; Chen, Jian-Min; Johansson, Bente B; Kirsten, Holger; Ruffert, Claudia; Masson, Emmanuelle; Steine, Solrun J; Bugert, Peter; Cnop, Miriam; Grützmann, Robert; Mayerle, Julia; Mössner, Joachim; Ringdal, Monika; Schulz, Hans-Ulrich; Sendler, Matthias; Simon, Peter; Sztromwasser, Paweł; Torsvik, Janniche; Scholz, Markus; Tjora, Erling; Férec, Claude; Witt, Heiko; Lerch, Markus M; Njølstad, Pål R; Johansson, Stefan; Molven, Anders

    2015-05-01

    Carboxyl ester lipase is a digestive pancreatic enzyme encoded by the CEL gene. Mutations in CEL cause maturity-onset diabetes of the young as well as pancreatic exocrine dysfunction. Here we describe a hybrid allele (CEL-HYB) originating from a crossover between CEL and its neighboring pseudogene, CELP. In a discovery series of familial chronic pancreatitis cases, we observed CEL-HYB in 14.1% (10/71) of cases compared to 1.0% (5/478) of controls (odds ratio (OR) = 15.5; 95% confidence interval (CI) = 5.1-46.9; P = 1.3 × 10(-6) by two-tailed Fisher's exact test). In three replication studies of nonalcoholic chronic pancreatitis, we identified CEL-HYB in a total of 3.7% (42/1,122) cases and 0.7% (30/4,152) controls (OR = 5.2; 95% CI = 3.2-8.5; P = 1.2 × 10(-11); formal meta-analysis). The allele was also enriched in alcoholic chronic pancreatitis. Expression of CEL-HYB in cellular models showed reduced lipolytic activity, impaired secretion, prominent intracellular accumulation and induced autophagy. These findings implicate a new pathway distinct from the protease-antiprotease system of pancreatic acinar cells in chronic pancreatitis.

  12. A recombined allele of the lipase gene CEL and its pseudogene CELP confers susceptibility to chronic pancreatitis

    PubMed Central

    Fjeld, Karianne; Johansson, Bente B.; Kirsten, Holger; Ruffert, Claudia; Masson, Emmanuelle; Steine, Solrun J.; Bugert, Peter; Cnop, Miriam; Grützmann, Robert; Mayerle, Julia; Mössner, Joachim; Ringdal, Monika; Schulz, Hans-Ulrich; Sendler, Matthias; Simon, Peter; Sztromwasser, Paweł; Torsvik, Janniche; Scholz, Markus; Tjora, Erling; Férec, Claude; Witt, Heiko; Lerch, Markus M.; Njølstad, Pål R.; Johansson, Stefan; Molven, Anders

    2015-01-01

    Carboxyl-ester lipase is a digestive pancreatic enzyme encoded by the highly polymorphic CEL gene1. Mutations in CEL cause maturity-onset diabetes of the young (MODY) with pancreatic exocrine dysfunction2. Here we identified a hybrid allele (CEL-HYB), originating from a crossover between CEL and its neighboring pseudogene CELP. In a discovery cohort of familial chronic pancreatitis cases, the carrier frequency of CEL-HYB was 14.1% (10/71) compared with 1.0% (5/478) in controls (odds ratio [OR] = 15.5, 95% confidence interval [CI] = 5.1-46.9, P = 1.3 × 10−6). Three replication studies in non-alcoholic chronic pancreatitis cohorts identified CEL-HYB in a total of 3.7% (42/1,122) cases and 0.7% (30/4,152) controls (OR = 5.2, 95% CI = 3.2-8.5, P = 1.2 × 10−11; formal meta-analysis). The allele was also enriched in alcoholic chronic pancreatitis. Expression of CEL-HYB in cellular models revealed reduced lipolytic activity, impaired secretion, prominent intracellular accumulation and induced autophagy. The hybrid variant of CEL is the first chronic pancreatitis gene identified outside the protease/antiprotease system of pancreatic acinar cells. PMID:25774637

  13. Different Alleles of a Gene Encoding Leucoanthocyanidin Reductase (PaLAR3) Influence Resistance against the Fungus Heterobasidion parviporum in Picea abies.

    PubMed

    Nemesio-Gorriz, Miguel; Hammerbacher, Almuth; Ihrmark, Katarina; Källman, Thomas; Olson, Åke; Lascoux, Martin; Stenlid, Jan; Gershenzon, Jonathan; Elfstrand, Malin

    2016-08-01

    Despite the fact that fungal diseases are a growing menace for conifers in modern silviculture, only a very limited number of molecular markers for pathogen resistance have been validated in conifer species. A previous genetic study indicated that the resistance of Norway spruce (Picea abies) to Heterobasidion annosum s.l., a pathogenic basidiomycete species complex, is linked to a quantitative trait loci that associates with differences in fungal growth in sapwood (FGS) that includes a gene, PaLAR3, which encodes a leucoanthocyanidin reductase. In this study, gene sequences showed the presence of two PaLAR3 allelic lineages in P. abies. Higher resistance was associated with the novel allele, which was found in low frequency in the four P. abies populations that we studied. Norway spruce plants carrying at least one copy of the novel allele showed a significant reduction in FGS after inoculation with Heterobasidion parviporum compared to their half-siblings carrying no copies, indicating dominance of this allele. The amount of (+) catechin, the enzymatic product of PaLAR3, was significantly higher in bark of trees homozygous for the novel allele. Although we observed that the in vitro activities of the enzymes encoded by the two alleles were similar, we could show that allele-specific transcript levels were significantly higher for the novel allele, indicating that regulation of gene expression is responsible for the observed effects in resistance, possibly caused by differences in cis-acting elements that we observe in the promoter region of the two alleles.

  14. Quantitative resistance affects the speed of frequency increase but not the diversity of the virulence alleles overcoming a major resistance gene to Leptosphaeria maculans in oilseed rape.

    PubMed

    Delourme, R; Bousset, L; Ermel, M; Duffé, P; Besnard, A L; Marquer, B; Fudal, I; Linglin, J; Chadœuf, J; Brun, H

    2014-10-01

    Quantitative resistance mediated by multiple genetic factors has been shown to increase the potential for durability of major resistance genes. This was demonstrated in the Leptosphaeria maculans/Brassica napus pathosystem in a 5year recurrent selection field experiment on lines harboring the qualitative resistance gene Rlm6 combined or not with quantitative resistance. The quantitative resistance limited the size of the virulent isolate population. In this study we continued this recurrent selection experiment in the same way to examine whether the pathogen population could adapt and render the major gene ineffective in the longer term. The cultivars Eurol, with a susceptible background, and Darmor, with quantitative resistance, were used. We confirmed that the combination of qualitative and quantitative resistance is an effective approach for controlling the pathogen epidemics over time. This combination did not prevent isolates virulent against the major gene from amplifying in the long term but the quantitative resistance significantly delayed for 5years the loss of effectiveness of the qualitative resistance and disease severity was maintained at a low level on the genotype with both types of resistance after the fungus population had adapted to the major gene. We also showed that diversity of AvrLm6 virulence alleles was comparable in isolates recovered after the recurrent selection on lines carrying either the major gene alone or in combination with quantitative resistance: a single repeat-induced point mutation and deletion events were observed in both situations. Breeding varieties which combine qualitative and quantitative resistance can effectively contribute to disease control by increasing the potential for durability of major resistance genes.

  15. mmr, a Mycobacterium tuberculosis Gene Conferring Resistance to Small Cationic Dyes and Inhibitors

    PubMed Central

    De Rossi, Edda; Branzoni, Manuela; Cantoni, Rita; Milano, Anna; Riccardi, Giovanna; Ciferri, Orio

    1998-01-01

    The mmr gene, cloned from Mycobacterium tuberculosis, was shown to confer to Mycobacterium smegmatis resistance to tetraphenylphosphonium (TPP), erythromycin, ethidium bromide, acriflavine, safranin O, and pyronin Y. The gene appears to code for a protein containing four transmembrane domains. Studies of [3H]TPP intracellular accumulation strongly suggest that the resistance mediated by the Mmr protein involves active extrusion of TPP. PMID:9811672

  16. Lack of associations between HLA class II alleles and resistance to HIV-1 infection among white, non-Hispanic homosexual men.

    PubMed

    Liu, Chenglong; Carrington, Mary; Kaslow, Richard A; Gao, Xiaojiang; Rinaldo, Charles R; Jacobson, Lisa P; Margolick, Joseph B; Phair, John; O'Brien, Stephen J; Detels, Roger

    2004-10-01

    HLA class II alleles were molecularly typed for 100 high-risk seronegative men and 184 low-risk seroconverters from the Multicenter AIDS Cohort Study (MACS). Seven resistant individuals homozygous for CCR5 Delta32 deletions were excluded from analysis. In the univariate analysis, no significant HLA class II associations with resistance/susceptibility to HIV type 1 infection were identified. However, the transporter associated with antigen presentation 2 (TAP2) Ala 665 variant associated with resistance in earlier analyses in the MACS was in linkage disequilibrium with some HLA class II alleles. After adjusting for the established associations with HLA-A*0205 subgroup and TAP2 Ala 665 variant, no HLA class II alleles were independently associated with resistance/susceptibility to HIV-1 infection. Other genetic factors in the HLA class II-TAP region of the major histocompatibility complex might be involved.

  17. A novel phakopsora pachyrhizi resistance allele (rpp) contributed by PI 567068A

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soybean rust (SBR) caused by the obligate, fungal pathogen Phakopsora pachyrhizi is an economic threat to soybean production, especially in the Americas. Host plant resistance is an important management strategy for SBR. The most recently described resistance to P. pachyrhizi (Rpp) gene is Rpp6 co...

  18. A new soybean rust resistance allele from PI 423972 at the Rpp4 locus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Phakopsora pachyrhizi is a fungal pathogen and the cause of Asian soybean rust (SBR). P. pachyrhizi invaded the continental United States in 2004 and has since been a threat to the soybean industry. There are six described loci that harbor resistance to P. pachyrhizi (Rpp) genes. The resistance of P...

  19. Insights into the Enhanced in vivo Fitness of Neisseria gonorrhoeae Driven by a Fluoroquinolone Resistance-Conferring Mutant DNA Gyrase

    DTIC Science & Technology

    2015-02-05

    Insights into the Enhanced in vivo Fitness of Neisseria gonorrhoeae Driven by a Fluoroquinolone Resistance-Conferring Mutant DNA Gyrase...gonorrhoeae Driven by a Fluoroquinolone Resistance-Conferring Mutant DNA Gyrase" Name of Candidate: MAJ Jonathan D’ Ambrozio Doctor of Philosophy Degree...gonorrhoeae Driven by a Fluoroquinolone Resistance-Conferring Mutant DNA Gyrase" is appropriately acknowledged and, bey9nd brief excerpts, is with

  20. Dispensable ribosomal resistance to spiramycin conferred by srmA in the spiramycin producer Streptomyces ambofaciens.

    PubMed

    Pernodet, J L; Gourmelen, A; Blondelet-Rouault, M H; Cundliffe, E

    1999-09-01

    Streptomyces ambofaciens produces the macrolide antibiotic spiramycin, an inhibitor of protein synthesis, and possesses multiple resistance mechanisms to the produced antibiotic. Several resistance determinants have been isolated from S. ambofaciens and studies with one of them, srmA, which hybridized with ermE (the erythromycin-resistance gene from Saccharopolyspora erythraea), are detailed here. The nucleotide sequence of srmA was determined and the mechanism by which its product confers resistance was characterized. The SrmA protein is a methyltransferase which introduces a single methyl group into A-2058 (Escherichia coli numbering scheme) in the large rRNA, thereby conferring an MLS (macrolide-lincosamide-streptogramin type B) type I resistance phenotype. A mutant of S. ambofaciens in which srmA was inactivated was viable and still produced spiramycin, indicating that srmA is dispensable, at least in the presence of the other resistance determinants.

  1. HLA-B*51 and B*15 alleles confer predisposition to Behçet's disease in Moroccan patients.

    PubMed

    Choukri, F; Chakib, A; Himmich, H; Hüe, S; Caillat-Zucman, S

    2001-02-01

    HLA class I polymorphism in Moroccan patients with Behçet's disease has not been investigated so far. In this study, HLA-B* phenotype frequencies were analyzed in 86 unrelated Moroccan patients (45 males, 41 females) and 111 ethnically matched healthy controls. The predisposing effect of the B*51 was confirmed (30.2% in patients and 15.3% in controls, OR = 2.39, 95% CI [1.2-4.8], p = 0.015). It was mostly observed in males with young age at disease onset (OR= 5.5 [1.9-15.9], p = 0.002 compared to controls). The Moroccan BD group also presented a previously unknown association with HLA-B*15 (25.6% of patients versus 11.7% of controls, OR = 2.59 [1.2-5.5], p = 0.014), both in females and in males with late-onset of the disease. Altogether, the B*15 and/or B*51 alleles were expressed in 55.8% of patients compared to 27% of controls (OR = 3.4 [1.9-6.2], p < 10-4, Pc = 0.003). Our data indicate HLA-B effects on BD pathogenesis should be considered separately for men and women.

  2. Intrinsic Macrolide Resistance in Mycobacterium smegmatis Is Conferred by a Novel erm Gene, erm(38)

    PubMed Central

    Nash, Kevin A.

    2003-01-01

    High-level, acquired macrolide resistance in mycobacteria is conferred by mutation within the 23S rRNA gene. However, several mycobacteria are naturally resistant to macrolides, including the Mycobacterium smegmatis group and Mycobacterium tuberculosis complex. Thus, the aim of this study was to characterize this resistance. Intrinsic macrolide resistance in M. smegmatis was inducible and showed cross-resistance to lincosamides but not to streptogramin B (i.e., ML resistance). A similar phenotype was found with Mycobacterium microti and macrolide-resistant Mycobacterium fortuitum. A search of the DNA sequence data for M. smegmatis strain mc2155 identified a novel erm gene, erm(38), and expression analysis showed that erm(38) RNA levels increased >10-fold after a 2-h incubation with macrolide. Inducible ML resistance was not expressed by an erm(38) knockout mutant, and complementation of this mutant with intact erm(38) in trans resulted in high-level ML resistance (e.g., clarithromycin MIC of >512 μg/ml). Thus, the results indicate that erm(38) confers the intrinsic ML resistance of M. smegmatis. Southern blot analysis with an erm(38)-specific probe indicated that a similar gene may be present in macrolide-resistant M. fortuitum. This finding, with the presence of the erm(37) gene (Rv1988) in the M. tuberculosis complex, suggests that such genes are widespread in mycobacteria with intrinsic macrolide resistance. PMID:14506008

  3. Analysis of Pneumocystis jirovecii DHPS alleles implicated in sulfamethoxazole resistance using an Escherichia coli model system.

    PubMed

    Iliades, Peter; Meshnick, Steven R; Macreadie, Ian G

    2005-01-01

    Pneumocystis jirovecii is a major opportunistic pathogen that causes Pneumocystis pneumonia (PCP). Drug treatment failure has been associated epidemiologically with point mutations in the gene for dihydropteroate synthase which is part of a gene that encodes three covalently linked enzymes involved in folic acid synthesis (FAS). The evaluation of whether mutations found in P. jirovecii FAS lead to sulfa drug resistance is hampered by the lack of a culture system for P. jirovecii as well as the failure of P. jirovecii FAS to complement in a heterologous system. Therefore, we chose to model the P. jirovecii mutations in the Saccharomyces cerevisiae FAS protein (encoded by FOL1) via its expression in Escherichia coli. An optimized drug diffusion assay was used to evaluate the FAS mutants against 15 sulfa drugs. It was established that the single amino acid substitution, P599S, in the (DHPS) domain of FAS led to sulfa drug resistance, whereas the T597A substitution led to increased sensitivity. The presence of both mutations (T597A and P599S) was cooperative and led to increased sulfa drug resistance. Analysis of a novel double mutant, (T597V P599S) was found to have significantly higher sulfa drug resistance than the T597A P599S mutant. These data suggest that further amino acid substitutions may lead to the evolution of higher sulfa drug resistance. Two sulfa drugs (sulfachloropyridazine and sulfathiazole) were identified that had higher inhibitory potential than sulfamethoxazole, which is currently the preferred treatment for PCP.

  4. [The differences of the effects of Vrd1 and Ppd-D1 gene alleles on winterhardiness, frost resistance, and yield in winter wheat].

    PubMed

    Mokanu, N V; Faĭt, V I

    2008-01-01

    The influence of allelic differences of Vrd1 and Ppd-D1 genes on winterhardiness, frost resistance, yield and its components was studied in recombinant-inbred F5 lines of Odesskaya 16/Bezostaya 1. From 9 to 15% differences in the resistance of recombinant-inbred lines were determined by alternative alleles of Vrd1 gene and 10-16% of Ppd-D1 gene. Interaction of vrd1 and Ppd-D1a alleles led to the higher winterhardiness and frost resistance of tillered plants during the winter. At the same time the significant increase of the period to heading, plant height and the tendency of yield reduction were revealed for vrd1 vrd1 Ppd-D1a Ppd-D1a lines when compared to the lines of Vrd1 Vrd1 Ppd-D1a Ppd-D1a genotype.

  5. HLA-DRB1-DQB1 Haplotypes Confer Susceptibility and Resistance to Multiple Sclerosis in Sardinia

    PubMed Central

    Cocco, Eleonora; Sardu, Claudia; Pieroni, Enrico; Valentini, Maria; Murru, Raffaele; Costa, Gianna; Tranquilli, Stefania; Frau, Jessica; Coghe, Giancarlo; Carboni, Nicola; Floris, Matteo; Contu, Paolo; Marrosu, Maria Giovanna

    2012-01-01

    :02, *06:01 alleles. Conclusions These findings show that the association of specific, independent DRB1*-DQB1* haplotypes confers susceptibility or resistance to MS in the MS-prone Sardinian population. The data also supports a functional role for specific residues of the DRB1 and DQB1 proteins in predisposing patients to MS. PMID:22509268

  6. Leaf rust resistance in wheat line RL6062 is an allele at the Lr3 locus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    RL6062, a 'Thatcher' backcross line of wheat (Triticum aestivum L.) has resistance to leaf rust (caused by Puccinia triticina) derived from a line of common wheat from Iran. RL6062 has an intermediate infection type (IT) of small to moderate uredinia surrounded by distinct chlorosis. RL6062 was cros...

  7. An MDR1 promoter allele with higher promoter activity is common in clinically isolated strains of Candida albicans

    PubMed Central

    Bruzual, Igor

    2013-01-01

    In the opportunistic fungal pathogen Candida albicans, up-regulation of MDR1, encoding an efflux transporter, leads to increased resistance to the antifungal drug fluconazole. Antifungal resistance has been linked to several types of genetic change in C. albicans, including changes in genome structure, genetic alteration of the drug target, and overexpression of transporters. High-level over-expression of MDR1 is commonly mediated by mutation in a trans-acting factor, Mrr1p. This report describes a second mechanism that contributes to up-regulation of MDR1 expression. By analyzing the sequence of the MDR1 promoter region in fluconazole-resistant and fluconazole-susceptible strains, we identified sequence polymorphisms that defined two linkage groups, corresponding to the two alleles in the diploid genome. One of the alleles conferred higher MDR1 expression compared with the other allele. Strains in which both alleles were of the higher activity type were common in collections of clinically isolated strains while strains carrying only the less active allele were rare. As increased expression of MDR1 confers higher resistance to drugs, strains with the more active MDR1 promoter allele may grow or survive longer when exposed to drugs or other selective pressures, providing greater opportunity for mutations that confer high-level drug resistance to arise. Through this mechanism, higher activity alleles of the MDR1 promoter could promote the development of drug resistance. PMID:21972105

  8. Gene amplification confers glyphosate resistance in Amaranthus palmeri

    PubMed Central

    Gaines, Todd A.; Zhang, Wenli; Wang, Dafu; Bukun, Bekir; Chisholm, Stephen T.; Shaner, Dale L.; Nissen, Scott J.; Patzoldt, William L.; Tranel, Patrick J.; Culpepper, A. Stanley; Grey, Timothy L.; Webster, Theodore M.; Vencill, William K.; Sammons, R. Douglas; Jiang, Jiming; Preston, Christopher; Leach, Jan E.; Westra, Philip

    2009-01-01

    The herbicide glyphosate became widely used in the United States and other parts of the world after the commercialization of glyphosate-resistant crops. These crops have constitutive overexpression of a glyphosate-insensitive form of the herbicide target site gene, 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS). Increased use of glyphosate over multiple years imposes selective genetic pressure on weed populations. We investigated recently discovered glyphosate-resistant Amaranthus palmeri populations from Georgia, in comparison with normally sensitive populations. EPSPS enzyme activity from resistant and susceptible plants was equally inhibited by glyphosate, which led us to use quantitative PCR to measure relative copy numbers of the EPSPS gene. Genomes of resistant plants contained from 5-fold to more than 160-fold more copies of the EPSPS gene than did genomes of susceptible plants. Quantitative RT-PCR on cDNA revealed that EPSPS expression was positively correlated with genomic EPSPS relative copy number. Immunoblot analyses showed that increased EPSPS protein level also correlated with EPSPS genomic copy number. EPSPS gene amplification was heritable, correlated with resistance in pseudo-F2 populations, and is proposed to be the molecular basis of glyphosate resistance. FISH revealed that EPSPS genes were present on every chromosome and, therefore, gene amplification was likely not caused by unequal chromosome crossing over. This occurrence of gene amplification as an herbicide resistance mechanism in a naturally occurring weed population is particularly significant because it could threaten the sustainable use of glyphosate-resistant crop technology. PMID:20018685

  9. Distribution of Voltage-Gated Sodium Channel (Nav) Alleles among the Aedes aegypti Populations In Central Java Province and Its Association with Resistance to Pyrethroid Insecticides

    PubMed Central

    Sayono, Sayono; Hidayati, Anggie Puspa Nur; Fahri, Sukmal; Sumanto, Didik; Dharmana, Edi; Hadisaputro, Suharyo; Asih, Puji Budi Setia; Syafruddin, Din

    2016-01-01

    The emergence of insecticide resistant Aedes aegypti mosquitoes has hampered dengue control efforts. WHO susceptibility tests, using several pyrethroid compounds, were conducted on Ae. aegypti larvae that were collected and raised to adulthood from Semarang, Surakarta, Kudus and Jepara in Java. The AaNaV gene fragment encompassing kdr polymorphic sites from both susceptible and resistant mosquitoes was amplified, and polymorphisms were associated with the resistant phenotype. The insecticide susceptibility tests demonstrated Ae, aegypti resistance to the pyrethroids, with mortality rates ranging from 1.6%–15.2%. Three non-synonymous polymorphisms (S989P, V1016G and F1534C) and one synonymous polymorphism (codon 982) were detected in the AaNaV gene. Eight AaNaV alleles were observed in specimens from Central Java. Allele 3 (SGF) and allele 7 (PGF) represent the most common alleles found and demonstrated strong associations with resistance to pyrethroids (OR = 2.75, CI: 0.97–7.8 and OR = 7.37, CI: 2.4–22.5, respectively). This is the first report of 8 Ae. aegypti AaNaV alleles, and it indicates the development of resistance in Ae. aegypti in response to pyrethroid insecticide-based selective pressure. These findings strongly suggest the need for an appropriate integrated use of insecticides in the region. The 989P, 1016G and 1534C polymorphisms in the AaNaV gene are potentially valuable molecular markers for pyrethroid insecticide resistance monitoring. PMID:26939002

  10. Allele mining in the gene pool of wild Solanum species for homologues of late blight resistance gene RB/Rpi-blb1

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Solanum bulbocastanum comprising a CC-NBS-LRR gene RB/Rpi-blb1 confers broad-spectrum resistance to Phytophthora infestans and is currently employed in potato breeding for durable late blight (LB) resistance. Genomes of several Solanum species were reported to contain RB homologues with confirmed b...

  11. Assessing the risk that Phytophthora melonis can develop a point mutation (V1109L) in CesA3 conferring resistance to carboxylic acid amide fungicides.

    PubMed

    Chen, Lei; Zhu, Shusheng; Lu, Xiaohong; Pang, Zhili; Cai, Meng; Liu, Xili

    2012-01-01

    The risk that the plant pathogen Phytophthora melonis develops resistance to carboxylic acid amide (CAA) fungicides was determined by measuring baseline sensitivities of field isolates, generating resistant mutants, and measuring the fitness of the resistant mutants. The baseline sensitivities of 80 isolates to flumorph, dimethomorph and iprovalicarb were described by unimodal curves, with mean EC(50) values of 0.986 (±0.245), 0.284 (±0.060) and 0.327 (±0.068) µg/ml, respectively. Seven isolates with different genetic background (as indicated by RAPD markers) were selected to generate CAA-resistance. Fifty-five resistant mutants were obtained from three out of seven isolates by spontaneous selection and UV-mutagenesis with frequencies of 1×10(-7) and 1×10(-6), respectively. CAA-resistance was stable for all mutants. The resistance factors of these mutants ranged from 7 to 601. The compound fitness index (CFI  =  mycelial growth × zoospore production × pathogenicity) was often lower for the CAA-resistant isolates than for wild-type isolates, suggesting that the risk of P. melonis developing resistance to CAA fungicides is low to moderate. Among the CAA-resistant isolates, a negative correlation between EC(50) values was found for iprovalicarb vs. flumorph and for iprovalicarb vs. dimethomorph. Comparison of the full-length cellulose synthase 3 (CesA3) between wild-type and CAA-resistant isolates revealed only one point mutation at codon position 1109: a valine residue (codon GTG in wild-type isolates) was converted to leucine (codon CTG in resistant mutants). This represents a novel point mutation with respect to mutations in CesA3 conferring resistance to CAA fungicides. Based on this mutation, an efficient allelic-specific PCR (AS-PCR) method was developed for rapid detection of CAA-resistance in P. melonis populations.

  12. Interfamily transfer of a plant pattern-recognition receptor confers broad-spectrum bacterial resistance.

    PubMed

    Lacombe, Séverine; Rougon-Cardoso, Alejandra; Sherwood, Emma; Peeters, Nemo; Dahlbeck, Douglas; van Esse, H Peter; Smoker, Matthew; Rallapalli, Ghanasyam; Thomma, Bart P H J; Staskawicz, Brian; Jones, Jonathan D G; Zipfel, Cyril

    2010-04-01

    Plant diseases cause massive losses in agriculture. Increasing the natural defenses of plants may reduce the impact of phytopathogens on agricultural productivity. Pattern-recognition receptors (PRRs) detect microbes by recognizing conserved pathogen-associated molecular patterns (PAMPs). Although the overall importance of PAMP-triggered immunity for plant defense is established, it has not been used to confer disease resistance in crops. We report that activity of a PRR is retained after its transfer between two plant families. Expression of EFR (ref. 4), a PRR from the cruciferous plant Arabidopsis thaliana, confers responsiveness to bacterial elongation factor Tu in the solanaceous plants Nicotiana benthamiana and tomato (Solanum lycopersicum), making them more resistant to a range of phytopathogenic bacteria from different genera. Our results in controlled laboratory conditions suggest that heterologous expression of PAMP recognition systems could be used to engineer broad-spectrum disease resistance to important bacterial pathogens, potentially enabling more durable and sustainable resistance in the field.

  13. Expression of the yeast cpd1 gene in tobacco confers resistance to the fungal toxin cercosporin.

    PubMed

    Panagiotis, Madesis; Kritonas, Kalantidis; Irini, Nianiou Obeidat; Kiriaki, Chatzidimitriou; Nicolaos, Panopoulos; Athanasios, Tsaftaris

    2007-06-01

    Many phytopathogenic species of the fungus Cercospora produce cercosporin, a photoactivated perylenequinone toxin that belongs to a family of photosensitizers, which absorb light energy and produce extremely cytotoxic, reactive oxygen species. The cpd1 (cercosporin photosensitizer detoxification) gene of yeast (Saccharomyces cerevisiae), which encodes for a novel protein with significant similarity to the FAD-dependent pyridine nucleotide reductases, confers resistance to cercosporin when over-expressed in yeast. The aim of this work was to investigate the potential ability of cpd1 gene to confer resistance to cercosporin when expressed in tobacco plants (Nicotiana tabacum). Transgenic tobacco plants were produced using Agrobacterium tumefaciens, with cpd1 integrated as the gene of interest. We report here that expression of cpd1 gene in tobacco can mediate resistance to cercosporin. The involvement of cpd1 gene in the detoxification of the cercosporin reinforces previous observations, which suggested that resistance to cercosporin is mediated by a mechanism involving toxin reduction.

  14. Detection of the V1016G mutation in the voltage-gated sodium channel gene of Aedes aegypti (Diptera: Culicidae) by allele-specific PCR assay, and its distribution and effect on deltamethrin resistance in Thailand

    PubMed Central

    2013-01-01

    Background Resistance to pyrethroid insecticides is widespread among populations of Aedes aegypti, the main vector for the dengue virus. Several different point mutations within the voltage-gated sodium channel (VGSC) gene contribute to such resistance. A mutation at position 1016 in domain II, segment 6 of the VGSC gene in Ae. aegypti leads to a valine to glycine substitution (V1016G) that confers resistance to deltamethrin. Methods This study developed and utilized an allele-specific PCR (AS-PCR) assay that could be used to detect the V1016G mutation. The assay was validated against a number of sequenced DNA samples of known genotype and was determined to be in complete agreement. Larvae and pupae were collected from various localities throughout Thailand. Samples were reared to adulthood and their resistance status against deltamethrin was determined by standard WHO susceptibility bioassays. Deltamethrin-resistant and susceptible insects were then genotyped for the V1016G mutation. Additionally, some samples were genotyped for a second mutation at position 1534 in domain III (F1534C) which is also known to confer pyrethroid resistance. Results The bioassay results revealed an overall mortality of 77.6%. Homozygous 1016G individuals survived at higher rates than either heterozygous or wild-type (1016 V) mosquitoes. The 1016G mutation was significantly and positively associated with deltamethrin resistance and was widely distributed throughout Thailand. Interestingly, wild-type 1016 V mosquitoes tested were homozygous for the 1534C mutation, and all heterozygous mosquitoes were also heterozygous for 1534C. Mutant homozygous (G/G) mosquitoes expressed the wild-type (F/F) at position 1534. However, the presence of the 1534C mutation was not associated with deltamethrin resistance. Conclusions Our bioassay results indicate that all populations sampled display some degree of resistance to deltamethrin. Homozygous 1016G mosquitoes were far likelier to survive such

  15. Conference on Fire Resistant Materials (FIREMEN): A compilation of presentations and papers

    NASA Technical Reports Server (NTRS)

    Kourtides, D. A. (Editor)

    1978-01-01

    The proceedings of the NASA Fire Resistant Materials Engineering (FIREMEN) Program held at Ames Research Center on April, 13, 14, 1978 are reported. The purpose of the conference was to discuss the results of NASA in the field of aircraft fire safety and fire resistant materials. The program components include the following: (1) large-scale testing; (2) fire toxicology; (3) polymeric materials; and (4) bibliography related and/or generated from the program.

  16. Conference on Fire Resistant Materials: A compilation of presentations and papers

    NASA Technical Reports Server (NTRS)

    Kourtides, D. A. (Editor); Johnson, G. A. (Editor)

    1979-01-01

    The proceedings of the NASA IRE Resistant Materials Engineering (FIREMEN) Program held at Boeing Commercial Airplane Company, Seattle, Washington, on March 1-2, 1979 are reported. The conference was to discuss the results of research by the National Aeronautics and Space Administration in the field of aircraft fire safety and fire-resistant materials. The program topics include the following: (1) large-scale testing; (2) fire toxicology; (3) polymeric materials; and (4) fire modeling.

  17. Induction of Xa10-like genes in rice cultivar Nipponbare confers disease resistance to rice bacterial blight.

    PubMed

    Wang, Jun; Tian, Dongsheng; Gu, Keyu; Yang, Xiaobei; Wang, Lanlan; Zeng, Xuan; Yin, Zhongchao

    2017-03-17

    Bacterial blight of rice, caused by Xanthomonas oryzae pv. oryzae, is one of the most destructive bacterial diseases throughout the major rice growing regions in the world. The rice disease resistance (R) genes Xa10 confers race-specific disease resistance to X. oryzae pv. oryzae strains that deliver the corresponding transcription activator-like (TAL) effectors AvrXa10. Upon bacterial infection, AvrXa10 binds specifically to the effector binding element (EBE) in the promoter of the R gene and activates its expression. Xa10 encodes an executor R protein that triggers hypersensitive response and activates disease resistance. Rice cultivar Nipponbare carries two Xa10-like genes in its genome, of which one is the susceptible allele of the Xa23 gene, a Xa10-like TAL effector-dependent executor R gene isolated recently from rice cultivar CBB23. However, the function of the two Xa10-like genes in disease resistance to X. oryzae pv. oryzae strains has not been investigated. Here we designated the two Xa10-like genes as Xa10-Ni and Xa23-Ni and characterized their function for disease resistance to rice bacterial blight. Both Xa10-Ni and Xa23-Ni provided disease resistance to X. oryzae pv. oryzae strains that deliver the matching artificially designed TAL effectors (dTALEs). Transgenic rice plants containing Xa10-Ni and Xa23-Ni under the Xa10 promoter provided specific disease resistance to X. oryzae pv. oryzae strains that deliver AvrXa10. Xa10-Ni and Xa23-Ni knock-out mutants abolished dTALE-dependent disease resistance to X. oryzae pv. oryzae. Heterologous expression of Xa10-Ni and Xa23-Ni in Nicotiana benthamiana triggered cell death. The 19-amino acid residues at the N-terminal regions of XA10 or XA10-Ni are dispensable for their function in inducing cell death in N. benthamiana and the C-terminal regions of XA10, XA10-Ni and XA23-Ni are interchangeable among each other without affecting their function. Like XA10, both XA10-Ni and XA23-Ni locate to the endoplasmic

  18. Molecular survey of turfgrass species for mutations conferring resistance to ACCase inhibiting herbicides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The control of grassy weeds in turfgrass is often problematic due to lack of herbicide selectivity. Seven different naturally occurring mutation sites have been reported to confer resistance to Acetyl coenzyme A carboxylase inhibiting herbicides. One or more of these mutation sites may hold potentia...

  19. Overexpression of Pto activates defense responses and confers broad resistance.

    PubMed Central

    Tang, X; Xie, M; Kim, Y J; Zhou, J; Klessig, D F; Martin, G B

    1999-01-01

    The tomato disease resistance (R) gene Pto specifies race-specific resistance to the bacterial pathogen Pseudomonas syringae pv tomato carrying the avrPto gene. Pto encodes a serine/threonine protein kinase that is postulated to be activated by a physical interaction with the AvrPto protein. Here, we report that overexpression of Pto in tomato activates defense responses in the absence of the Pto-AvrPto interaction. Leaves of three transgenic tomato lines carrying the cauliflower mosaic virus 35S::Pto transgene exhibited microscopic cell death, salicylic acid accumulation, and increased expression of pathogenesis-related genes. Cell death in these plants was limited to palisade mesophyll cells and required light for induction. Mesophyll cells of 35S::Pto plants showed the accumulation of autofluorescent compounds, callose deposition, and lignification. When inoculated with P. s. tomato without avrPto, all three 35S::Pto lines displayed significant resistance and supported less bacterial growth than did nontransgenic lines. Similarly, the 35S::Pto lines also were more resistant to Xanthomonas campestris pv vesicatoria and Cladosporium fulvum. These results demonstrate that defense responses and general resistance can be activated by the overexpression of an R gene. PMID:9878629

  20. Ribosomal Mutations Conferring Macrolide Resistance in Legionella pneumophila.

    PubMed

    Descours, Ghislaine; Ginevra, Christophe; Jacotin, Nathalie; Forey, Françoise; Chastang, Joëlle; Kay, Elisabeth; Etienne, Jerome; Lina, Gérard; Doublet, Patricia; Jarraud, Sophie

    2017-03-01

    Monitoring the emergence of antibiotic resistance is a recent issue in the treatment of Legionnaires' disease. Macrolides are recommended as first-line therapy, but resistance mechanisms have not been studied in Legionella species. Our aim was to determine the molecular basis of macrolide resistance in L. pneumophila Twelve independent lineages from a common susceptible L. pneumophila ancestral strain were propagated under conditions of erythromycin or azithromycin pressure to produce high-level macrolide resistance. Whole-genome sequencing was performed on 12 selected clones, and we investigated mutations common to all lineages. We reconstructed the dynamics of mutation for each lineage and demonstrated their involvement in decreased susceptibility to macrolides. The resistant mutants were produced in a limited number of passages to obtain a 4,096-fold increase in erythromycin MICs. Mutations affected highly conserved 5-amino-acid regions of L4 and L22 ribosomal proteins and of domain V of 23S rRNA (G2057, A2058, A2059, and C2611 nucleotides). The early mechanisms mainly affected L4 and L22 proteins and induced a 32-fold increase in the MICs of the selector drug. Additional mutations related to 23S rRNA mostly occurred later and were responsible for a major increase of macrolide MICs, depending on the mutated nucleotide, the substitution, and the number of mutated genes among the three rrl copies. The major mechanisms of the decreased susceptibility to macrolides in L. pneumophila and their dynamics were determined. The results showed that macrolide resistance could be easily selected in L. pneumophila and warrant further investigations in both clinical and environmental settings.

  1. Mutations of acetylcholinesterase which confer insecticide resistance in Drosophila melanogaster populations

    PubMed Central

    Menozzi, Philippe; Shi, Ming An; Lougarre, Andrée; Tang, Zhen Hua; Fournier, Didier

    2004-01-01

    Background Organophosphate and carbamate insecticides irreversibly inhibit acetylcholinesterase causing death of insects. Resistance-modified acetylcholinesterases(AChEs) have been described in many insect species and sequencing of their genes allowed several point mutations to be described. However, their relative frequency and their cartography had not yet been addressed. Results To analyze the most frequent mutations providing insecticide resistance in Drosophila melanogaster acetylcholinesterase, the Ace gene was cloned and sequenced in several strains harvested from different parts of the world. Sequence comparison revealed four widespread mutations, I161V, G265A, F330Y and G368A. We confirm here that mutations are found either isolated or in combination in the same protein and we show that most natural populations are heterogeneous, composed of a mixture of different alleles. In vitro expression of mutated proteins showed that combining mutations in the same protein has two consequences: it increases resistance level and provides a wide spectrum of resistance. Conclusion The presence of several alleles in natural populations, offering various resistance to carbamate and organophosphate compounds will complicate the establishment of resistance management programs. PMID:15018651

  2. Genome-Wide Association Implicates Candidate Genes Conferring Resistance to Maize Rough Dwarf Disease in Maize.

    PubMed

    Chen, Gengshen; Wang, Xiaoming; Hao, Junjie; Yan, Jianbing; Ding, Junqiang

    2015-01-01

    Maize rough dwarf disease (MRDD) is a destructive viral disease in China, which results in 20-30% of the maize yield losses in affected areas and even as high as 100% in severely infected fields. Understanding the genetic basis of resistance will provide important insights for maize breeding program. In this study, a diverse maize population comprising of 527 inbred lines was evaluated in four environments and a genome-wide association study (GWAS) was undertaken with over 556000 SNP markers. Fifteen candidate genes associated with MRDD resistance were identified, including ten genes with annotated protein encoding functions. The homologous of nine candidate genes were predicted to relate to plant defense in different species based on published results. Significant correlation (R2 = 0.79) between the MRDD severity and the number of resistance alleles was observed. Consequently, we have broadened the resistant germplasm to MRDD and identified a number of resistance alleles by GWAS. The results in present study also imply the candidate genes in defense pathway play an important role in resistance to MRDD in maize.

  3. Analysis of nucleotide diversity among alleles of the major bacterial blight resistance gene Xa27 in cultivars of rice (Oryza sativa) and its wild relatives.

    PubMed

    Bimolata, Waikhom; Kumar, Anirudh; Sundaram, Raman Meenakshi; Laha, Gouri Shankar; Qureshi, Insaf Ahmed; Reddy, Gajjala Ashok; Ghazi, Irfan Ahmad

    2013-08-01

    Xa27 is one of the important R-genes, effective against bacterial blight disease of rice caused by Xanthomonas oryzae pv. oryzae (Xoo). Using natural population of Oryza, we analyzed the sequence variation in the functionally important domains of Xa27 across the Oryza species. DNA sequences of Xa27 alleles from 27 rice accessions revealed higher nucleotide diversity among the reported R-genes of rice. Sequence polymorphism analysis revealed synonymous and non-synonymous mutations in addition to a number of InDels in non-coding regions of the gene. High sequence variation was observed in the promoter region including the 5'UTR with 'π' value 0.00916 and 'θ w ' = 0.01785. Comparative analysis of the identified Xa27 alleles with that of IRBB27 and IR24 indicated the operation of both positive selection (Ka/Ks > 1) and neutral selection (Ka/Ks ≈ 0). The genetic distances of alleles of the gene from Oryza nivara were nearer to IRBB27 as compared to IR24. We also found the presence of conserved and null UPT (upregulated by transcriptional activator) box in the isolated alleles. Considerable amino acid polymorphism was localized in the trans-membrane domain for which the functional significance is yet to be elucidated. However, the absence of functional UPT box in all the alleles except IRBB27 suggests the maintenance of single resistant allele throughout the natural population.

  4. Two genes conferring resistance to Pythium stalk rot in maize inbred line Qi319.

    PubMed

    Song, Feng-Jing; Xiao, Ming-Gang; Duan, Can-Xing; Li, Hong-Jie; Zhu, Zhen-Dong; Liu, Bao-Tao; Sun, Su-Li; Wu, Xiao-Fei; Wang, Xiao-Ming

    2015-08-01

    Stalk rots are destructive diseases in maize around the world, and are most often caused by the pathogen Pythium, Fusarium and other fungi. The most efficient management for controlling stalk rots is to breed resistant cultivars. Pythium stalk rot can cause serious yield loss on maize, and to find the resistance genes from the existing germplasm is the basis to develop Pythium-resistance hybrid lines. In this study, we investigated the genetic resistance to Pythium stalk rot in inbred line Qi319 using F2 and F2:3 population, and found that the resistance to Pythium inflatum in Qi319 was conferred by two independently inherited dominant genes, RpiQI319-1 and RpiQI319-2. Linkage analysis uncovered that the RpiQI319-1 co-segregated with markers bnlg1203, and bnlg2057 on chromosome 1, and that the RpiQI319-2 locus co-segregated with markers umc2069 and bnlg1716 on chromosome 10. The RpiQI319-1 locus was further mapped into a ~500-kb interval flanked by markers SSRZ33 and SSRZ47. These results will facilitate marker-assisted selection of Pythium stalk rot-resistant cultivars in maize breeding. To our knowledge, this is the first report on the resistance to P. inflatum in the inbred line Qi319, and is also the first description of two independently inherited dominant genes conferring the resistance of Pythium stalk rot in maize.

  5. Overexpression of an Arabidopsis thaliana ABC transporter confers kanamycin resistance to transgenic plants.

    PubMed

    Mentewab, Ayalew; Stewart, C Neal

    2005-09-01

    Selectable markers of bacterial origin such as the neomycin phosphotransferase type II gene, which can confer kanamycin resistance to transgenic plants, represent an invaluable tool for plant engineering. However, since all currently used antibiotic-resistance genes are of bacterial origin, there have been concerns about horizontal gene transfer from transgenic plants back to bacteria, which may result in antibiotic resistance. Here we characterize a plant gene, Atwbc19, the gene that encodes an Arabidopsis thaliana ATP binding cassette (ABC) transporter and confers antibiotic resistance to transgenic plants. The mechanism of resistance is novel, and the levels of resistance achieved are comparable to those attained through expression of bacterial antibiotic-resistance genes in transgenic tobacco using the CaMV 35S promoter. Because ABC transporters are endogenous to plants, the use of Atwbc19 as a selectable marker in transgenic plants may provide a practical alternative to current bacterial marker genes in terms of the risk for horizontal transfer of resistance genes.

  6. Pyocyanin Production by Pseudomonas aeruginosa Confers Resistance to Ionic Silver

    PubMed Central

    Merrett, Neil D.

    2014-01-01

    Silver in its ionic form (Ag+), but not the bulk metal (Ag0), is toxic to microbial life forms and has been used for many years in the treatment of wound infections. The prevalence of bacterial resistance to silver is considered low due to the nonspecific nature of its toxicity. However, the recent increased use of silver as an antimicrobial agent for medical, consumer, and industrial products has raised concern that widespread silver resistance may emerge. Pseudomonas aeruginosa is a common pathogen that produces pyocyanin, a redox toxin and a reductant for molecular oxygen and ferric (Fe3+) ions. The objective of this study was to determine whether pyocyanin reduces Ag+ to Ag0, which may contribute to silver resistance due to lower bioavailability of the cation. Using surface plasmon resonance spectroscopy and scanning electron microscopy, pyocyanin was confirmed to be a reductant for Ag+, forming Ag0 nanoparticles and reducing the bioavailability of free Ag+ by >95% within minutes. Similarly, a pyocyanin-producing strain of P. aeruginosa (PA14) reduced Ag+ but not a pyocyanin-deficient (ΔphzM) strain of the bacterium. Challenge of each strain with Ag+ (as AgNO3) gave MICs of 20 and 5 μg/ml for the PA14 and ΔphzM strains, respectively. Removal of pyocyanin from the medium strain PA14 was grown in or its addition to the medium that ΔphzM mutant was grown in gave MICs of 5 and 20 μg/ml, respectively. Clinical isolates demonstrated similar pyocyanin-dependent resistance to Ag+. We conclude that pseudomonal silver resistance exists independently of previously recognized intracellular mechanisms and may be more prevalent than previously considered. PMID:25001302

  7. Multidrug resistance conferred by novel DNA polymerase mutations in human cytomegalovirus isolates.

    PubMed

    Scott, Gillian M; Weinberg, Adriana; Rawlinson, William D; Chou, Sunwen

    2007-01-01

    The emergence of antiviral-resistant cytomegalovirus (CMV) strains is a continuing clinical problem, with increased numbers of immunocompromised patients given longer-duration antiviral prophylaxis. Two previously unrecognized CMV DNA polymerase mutations (N408K and A834P) identified separately and together in at-risk lung and kidney transplant recipients and a third mutation (L737M) identified in a liver transplant recipient were characterized by marker transfer to antiviral-sensitive laboratory strains AD169 and Towne. Subsequent phenotypic analyses of recombinant strains demonstrated the ability of mutation N408K to confer ganciclovir (GCV) and cidofovir (CDV) resistance and of mutation A834P to confer GCV, foscarnet, and CDV resistance. Mutation L737M did not confer resistance to any of the antiviral agents tested. A recombinant strain containing both N408K and A834P demonstrated increased GCV and CDV resistance compared to the levels of resistance of the virus containing only the A834P mutation. The addition of mutation N408K in combination with A834P also partially reconstituted the replication impairment of recombinant virus containing only A834P. This suggests that perturbation of both DNA polymerization (A834P) and exonuclease (N408K) activities contributes to antiviral resistance and altered replication kinetics in these mutant strains. The identification of these multidrug-resistant CMV strains in at-risk seronegative recipients of organs from seropositive donors suggests that improved prophylactic and treatment strategies are required. The additive effect of multiple mutations on antiviral susceptibility suggests that increasing antiviral-resistant phenotypes can result from different virus-antiviral interactions.

  8. An Arabidopsis thaliana ABC transporter that confers kanamycin resistance in transgenic plants does not endow resistance to Escherichia coli.

    PubMed

    Burris, Kellie; Mentewab, Ayalew; Ripp, Steven; Stewart, C Neal

    2008-03-01

    Concerns have been raised about potential horizontal gene transfer (HGT) of antibiotic resistance markers (ARMs) from transgenic plants to bacteria of medical and environmental importance. All ARMs used in transgenic plants have been bacterial in origin, but it has been recently shown that an Arabidopsis thaliana ABC transporter, Atwbc19, confers kanamycin resistance when overexpressed in transgenic plants. Atwbc19 was evaluated for its ability to transfer kanamycin resistance to Escherichia coli, a kanamycin-sensitive model bacterium, under simulated HGT, staged by subcloning Atwbc19 under the control of a bacterial promoter, genetically transforming to kanamycin-sensitive bacteria, and assessing if resistance was conferred as compared with bacteria harbouring nptII, the standard kanamycin resistance gene used to produce transgenic plants. NptII provided much greater resistance than Atwbc19 and was significantly different from the no-plasmid control at low concentrations. Atwbc19 was not significantly different from the no-plasmid control at higher concentrations. Even though HGT risks are considered low with nptII, Atwbc19 should have even lower risks, as its encoded protein is possibly mistargeted in bacteria.

  9. The 2NS Translocation from Aegilops ventricosa Confers Resistance to the Triticum Pathotype of Magnaporthe oryzae

    PubMed Central

    Cruz, C.D.; Peterson, G.L.; Bockus, W.W.; Kankanala, P.; Dubcovsky, J.; Jordan, K.W.; Akhunov, E.; Chumley, F.; Baldelomar, F.D.; Valent, B.

    2016-01-01

    Wheat blast is a serious disease caused by the fungus Magnaporthe oryzae (Triticum pathotype) (MoT). The objective of this study was to determine the effect of the 2NS translocation from Aegilops ventricosa (Zhuk.) Chennav on wheat head and leaf blast resistance. Disease phenotyping experiments were conducted in growth chamber, greenhouse, and field environments. Among 418 cultivars of wheat (Triticum aestivum L.), those with 2NS had 50.4 to 72.3% less head blast than those without 2NS when inoculated with an older MoT isolate under growth chamber conditions. When inoculated with recently collected isolates, cultivars with 2NS had 64.0 to 80.5% less head blast. Under greenhouse conditions when lines were inoculated with an older MoT isolate, those with 2NS had a significant head blast reduction. With newer isolates, not all lines with 2NS showed a significant reduction in head blast, suggesting that the genetic background and/or environment may influence the expression of any resistance conferred by 2NS. However, when near-isogenic lines (NILs) with and without 2NS were planted in the field, there was strong evidence that 2NS conferred resistance to head blast. Results from foliar inoculations suggest that the resistance to head infection that is imparted by the 2NS translocation does not confer resistance to foliar disease. In conclusion, the 2NS translocation was associated with significant reductions in head blast in both spring and winter wheat. PMID:27814405

  10. Methyltransferase Erm(37) slips on rRNA to confer atypical resistance in Mycobacterium tuberculosis.

    PubMed

    Madsen, Christian Toft; Jakobsen, Lene; Buriánková, Karolina; Doucet-Populaire, Florence; Pernodet, Jean-Luc; Douthwaite, Stephen

    2005-11-25

    Members of the Mycobacterium tuberculosis complex possess a resistance determinant, erm(37) (also termed ermMT), which is a truncated homologue of the erm genes found in a diverse range of drug-producing and pathogenic bacteria. All erm genes examined thus far encode N(6)-monomethyltransferases or N(6),N(6)-dimethyltransferases that show absolute specificity for nucleotide A2058 in 23 S rRNA. Monomethylation at A2058 confers resistance to a subset of the macrolide, lincosamide, and streptogramin B (MLS(B)) group of antibiotics and no resistance to the latest macrolide derivatives, the ketolides. Dimethylation at A2058 confers high resistance to all MLS(B) and ketolide drugs. The erm(37) phenotype fits into neither category. We show here by tandem mass spectrometry that Erm(37) initially adds a single methyl group to its primary target at A2058 but then proceeds to attach additional methyl groups to the neighboring nucleotides A2057 and A2059. Other methyltransferases, Erm(E) and Erm(O), maintain their specificity for A2058 on mycobacterial rRNA. Erm(E) and Erm(O) have a full-length C-terminal domain, which appears to be important for stabilizing the methyltransferases at their rRNA target, and this domain is truncated in Erm(37). The lax interaction of the M. tuberculosis Erm(37) with its rRNA produces a unique methylation pattern and confers resistance to the ketolide telithromycin.

  11. Genetic Interactions among Chlamydomonas Reinhardtii Mutations That Confer Resistance to anti-Microtubule Herbicides

    PubMed Central

    James, S. W.; Lefebvre, P. A.

    1992-01-01

    We previously described two types of genetic interactions among recessive mutations in the APM1 and APM2 loci of Chlamydomonas reinhardtii that may reflect a physical association of the gene products or their involvement in a common structure/process: (1) allele-specific synthetic lethality, and (2) unlinked noncomplementation, or dominant enhancement. To further investigate these interactions, we isolated revertants in which the heat sensitivity caused by the apm2-1 mutation is lost. The heat-insensitive revertants were either fully or partially suppressed for the drug-resistance caused by the apm2-1 allele. In recombination tests the revertants behaved as if the suppressing mutation mapped within the APM2 locus; the partial suppressors of apm2-1 herbicide resistance failed to complement apm2-1, leading to the conclusion that they were likely to be intragenic pseudorevertants. The apm2-1 partial suppressor mutations reversed apm1(-)apm2-1 synthetic lethality in an allele-specific manner with respect both to apm1(-) alleles and apm2-1 suppressor mutations. Those apm1(-) apm2-1(rev) strains that regained viability also regained heat sensitivity characteristic of the original apm2-1 mutation, even though the apm2-1 suppressor strains were fully heat-insensitive. The Hs(+) phenotypes of apm2-1 partial suppressors were also reversed by treatment with the microtubule-stabilizing agent deuterium oxide (D(2)O). In addition to the above interactions, we observed interallelic complementation and phenotypic enhancement of temperature conditionality among apm1(-) alleles. Evidence of a role for the products of the two genes in microtubule-based processes was obtained from studying flagellar assembly in apm1(-) and apm2(-) mutants. PMID:1311696

  12. Does left-handedness confer resistance to spatial bias?

    PubMed

    Bareham, Corinne A; Bekinschtein, Tristan A; Scott, Sophie K; Manly, Tom

    2015-03-17

    We recently demonstrated that drowsiness, indexed using EEG, was associated with left-inattention in a group of 26 healthy right-handers. This has been linked to alertness-related modulation of spatial bias in left neglect patients and the greater persistence of left, compared with right, neglect following injury. Despite handedness being among the most overt aspects of human lateralization, studies of this healthy analogue of left neglect have only been conducted with predominantly or exclusively right-handed individuals. Here, with a group of 26 healthy non-right-handers we demonstrate that, unlike right-handers who showed a rightward shift in attention with drowsiness, non-right-handers showed the opposite pattern on an auditory spatial localization task. The current results are the first indication that factors linked to handedness can affect the development and extremity of spatial biases, potentially conferring resilience to clinical symptoms in non-right-handers and, given that 90% of us are right-handed, why left neglect is disproportionately persistent.

  13. [Allelic state of the molecular marker for the golden nematode (Globodera rostochiensis) resistance gene H1 among Ukrainian and world cultivars of potato (Solanum tuberosum ssp. tuberosum)].

    PubMed

    Karelov, A V; Pilipenko, L A; Kozub, N A; Bondus, R A; Borzykh, A U; Sozinov, I A; Blium, Ia B; Sozinov, A A

    2013-01-01

    The purpose of our investigation was determination of allelic state of the H1 resistance gene against the pathotypes Ro1 and Ro4 of golden potato cyst nematode (Globodera rostochiensis) among Ukrainian and world potato (Solanum tuberosum ssp. tuberosum) cultivars. The allelic condition of the TG689 marker was determined by PCR with DNA samples isolated from tubers of potato and primers, one pair of which flanks the allele-specific region and the other one was used for the control of DNA quality. Among analyzed 77 potato cultivars the allele of marker associated with the H1-type resistance was found in 74% of Ukrainian and 90% foreign ones although some of those cultivars proved to be susceptible to the golden potato nematode in field. The obtained data confirm the presence of H1-resistance against golden nematode pathotypes Ro1 and Ro4 among the Ukrainian potato cultivars and efficiency of the used marker within the accuracy that has been declared by its authors.

  14. [Cloning and analyzing of rice blast resistance gene Pi-ta+ allele from Jinghong erect type of common wild rice (Oryza rufipogon Griff) in Yunnan].

    PubMed

    Geng, Xian-Sheng; Yang, Ming-Zhi; Huang, Xing-Qi; Cheng, Zai-Quan; Fu, Jian; Sun, Tao; Li, Jun

    2008-01-01

    A 4,672 bp DNA sequence including the whole coding region and partial non-coding region of rice blast resistance gene Pi-ta+ has been cloned from Jinghong erect type of common wild rice (Oryza rufipogon Griff) in Yunnan by polymerase chain reaction method. The coding region shares 99.86% and 98.78% identity with the corresponding regions of the reported cultivated rice Yashiro-mochi and Yuanjiang type of common wild rice respectively. There are 4 nucleotides difference in the coding region and 6 in intron of the cloned Pi-ta+ gene,compared with Pi-ta from Yashiro-mochi. Pi-ta+ gene in Jinghong erect type of common wild rice has been proved to be a rare existing Pi-ta+ allele, because there was a alanine rather than a serine at the position 918 within the predicted amino acid sequence of PITA. Pi-ta+ allele can cause disease resistance response to rice blast pathogens in plant cells. Differences in DNA sequence, deduced amino acid sequence and antibacterial spectrum may make the Pi-ta+ allele new resistant characteristics. Finding and cloning of Pi-ta+ allele from Jinghong erect type of common wild rice in Yunnan provides a basement for further utilization of the wild rice resources.

  15. Mutations in the Pneumocystis jirovecii DHPS gene confer cross-resistance to sulfa drugs.

    PubMed

    Iliades, Peter; Meshnick, Steven R; Macreadie, Ian G

    2005-02-01

    Pneumocystis jirovecii is a major opportunistic pathogen that causes Pneumocystis pneumonia (PCP) and results in a high degree of mortality in immunocompromised individuals. The drug of choice for PCP is typically sulfamethoxazole (SMX) or dapsone in conjunction with trimethoprim. Drug treatment failure and sulfa drug resistance have been implicated epidemiologically with point mutations in dihydropteroate synthase (DHPS) of P. jirovecii. P. jirovecii cannot be cultured in vitro; however, heterologous complementation of the P. jirovecii trifunctional folic acid synthesis (PjFAS) genes with an E. coli DHPS-disrupted strain was recently achieved. This enabled the evaluation of SMX resistance conferred by DHPS mutations. In this study, we sought to determine whether DHPS mutations conferred sulfa drug cross-resistance to 15 commonly available sulfa drugs. It was established that the presence of amino acid substitutions (T(517)A or P(519)S) in the DHPS domain of PjFAS led to cross-resistance against most sulfa drugs evaluated. The presence of both mutations led to increased sulfa drug resistance, suggesting cooperativity and the incremental evolution of sulfa drug resistance. Two sulfa drugs (sulfachloropyridazine [SCP] and sulfamethoxypyridazine [SMP]) that had a higher inhibitory potential than SMX were identified. In addition, SCP, SMP, and sulfadiazine (SDZ) were found to be capable of inhibiting the clinically observed drug-resistant mutants. We propose that SCP, SMP, and SDZ should be considered for clinical evaluation against PCP or for future development of novel sulfa drug compounds.

  16. Dating the origin of the CCR5-Delta32 AIDS-resistance allele by the coalescence of haplotypes.

    PubMed Central

    Stephens, J C; Reich, D E; Goldstein, D B; Shin, H D; Smith, M W; Carrington, M; Winkler, C; Huttley, G A; Allikmets, R; Schriml, L; Gerrard, B; Malasky, M; Ramos, M D; Morlot, S; Tzetis, M; Oddoux, C; di Giovine, F S; Nasioulas, G; Chandler, D; Aseev, M; Hanson, M; Kalaydjieva, L; Glavac, D; Gasparini, P; Kanavakis, E; Claustres, M; Kambouris, M; Ostrer, H; Duff, G; Baranov, V; Sibul, H; Metspalu, A; Goldman, D; Martin, N; Duffy, D; Schmidtke, J; Estivill, X; O'Brien, S J; Dean, M

    1998-01-01

    The CCR5-Delta32 deletion obliterates the CCR5 chemokine and the human immunodeficiency virus (HIV)-1 coreceptor on lymphoid cells, leading to strong resistance against HIV-1 infection and AIDS. A genotype survey of 4,166 individuals revealed a cline of CCR5-Delta32 allele frequencies of 0%-14% across Eurasia, whereas the variant is absent among native African, American Indian, and East Asian ethnic groups. Haplotype analysis of 192 Caucasian chromosomes revealed strong linkage disequilibrium between CCR5 and two microsatellite loci. By use of coalescence theory to interpret modern haplotype genealogy, we estimate the origin of the CCR5-Delta32-containing ancestral haplotype to be approximately 700 years ago, with an estimated range of 275-1,875 years. The geographic cline of CCR5-Delta32 frequencies and its recent emergence are consistent with a historic strong selective event (e.g. , an epidemic of a pathogen that, like HIV-1, utilizes CCR5), driving its frequency upward in ancestral Caucasian populations. PMID:9585595

  17. Overexpression of the chromosomally encoded aminoglycoside acetyltransferase eis confers kanamycin resistance in Mycobacterium tuberculosis.

    PubMed

    Zaunbrecher, M Analise; Sikes, R David; Metchock, Beverly; Shinnick, Thomas M; Posey, James E

    2009-11-24

    The emergence of multidrug-resistant (MDR) tuberculosis (TB) highlights the urgent need to understand the mechanisms of resistance to the drugs used to treat this disease. The aminoglycosides kanamycin and amikacin are important bactericidal drugs used to treat MDR TB, and resistance to one or both of these drugs is a defining characteristic of extensively drug-resistant TB. We identified mutations in the -10 and -35 promoter region of the eis gene, which encodes a previously uncharacterized aminoglycoside acetyltransferase. These mutations led to a 20-180-fold increase in the amount of eis leaderless mRNA transcript, with a corresponding increase in protein expression. Importantly, these promoter mutations conferred resistance to kanamycin [5 microg/mL < minimum inhibitory concentration (MIC) resistance harbored eis promoter mutations. These results have important clinical implications in that clinical isolates determined to be resistant to kanamycin may not be cross-resistant to amikacin, as is often assumed. Molecular detection of eis mutations should distinguish strains resistant to kanamycin and those resistant to kanamycin and amikacin. This may help avoid excluding a potentially effective drug from a treatment regimen for drug-resistant TB.

  18. [Genetic mechanisms of resistance and susceptibility to leukemia in Ayrshire and black pied cattle breeds determined by allelic distribution of gene Bola-DRB3].

    PubMed

    Udina, I G; Karamysheva, E E; Turkova, S O; Orlova, A R; Sulimova, G E

    2003-03-01

    In the herds of Ayrshire and Black Pied cattle breeds of Russian selection, comparative analysis of allelic distribution of BoLA-DRB3 was performed in animal groups with different status of persistent lymphocytosis (PL) caused by the bovine leukemia virus (BLV). Alleles were typed by PCR-RFLP. Different spectra of BoLA-DRB3 alleles mediating susceptibility and resistance to leukemia were detected in the studied breeds. The role of amino acid motives in beta 1 domain of BoLA-DRB3 antigens was confirmed: ER (in positions 70-71), in resistance to leukemia and VDTY and VDTV (75-78), in susceptibility to leukemia. The nucleotide sequence of allele BoLA-DRB3.2*7 with deletion of codon 65, which resulted in the changed conformation of the corresponding antigen molecule, was associated with resistance to PL. Cows of Black Pied and Ayrshire breeds with genotypes coding VDTY/VDTV (RR = 11.67, P = 0.014) and VDTY/VDTY (RR = 4.71, P = 0.022), respectively, were shown to be susceptible to PL. The role of heterozygosity level was demonstrated (estimated by BoLA-DRB3 alleles and by amino acid motives in positions 75-78 of the antigen) as an unspecific factor of resistance to PL. The lowest heterozygosity level by amino acid motives (75-78) was revealed in PL animals, for which sample inbreeding coefficients were detected: F = 0.324 and F = 0.084 in Ayrshire and Black Pied breeds, respectively.

  19. Ovine progressive pneumonia provirus levels are unaffected by the prion 171R allele in an Idaho sheep flock

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Selective breeding of sheep for arginine (R) at prion gene (PRNP) codon 171 confers resistance to Scrapie. The 171R allele naturally occurs at low frequency, possibly because it imparts a deleterious trait such as impaired disease resistance. Ovine Progressive Pneumonia/Maedi-Visna virus (OPPV) is...

  20. The genetic basis of resistance and matching-allele interactions of a host-parasite system: The Daphnia magna-Pasteuria ramosa model.

    PubMed

    Bento, Gilberto; Routtu, Jarkko; Fields, Peter D; Bourgeois, Yann; Du Pasquier, Louis; Ebert, Dieter

    2017-02-21

    Negative frequency-dependent selection (NFDS) is an evolutionary mechanism suggested to govern host-parasite coevolution and the maintenance of genetic diversity at host resistance loci, such as the vertebrate MHC and R-genes in plants. Matching-allele interactions of hosts and parasites that prevent the emergence of host and parasite genotypes that are universally resistant and infective are a genetic mechanism predicted to underpin NFDS. The underlying genetics of matching-allele interactions are unknown even in host-parasite systems with empirical support for coevolution by NFDS, as is the case for the planktonic crustacean Daphnia magna and the bacterial pathogen Pasteuria ramosa. We fine-map one locus associated with D. magna resistance to P. ramosa and genetically characterize two haplotypes of the Pasteuria resistance (PR-) locus using de novo genome and transcriptome sequencing. Sequence comparison of PR-locus haplotypes finds dramatic structural polymorphisms between PR-locus haplotypes including a large portion of each haplotype being composed of non-homologous sequences resulting in haplotypes differing in size by 66 kb. The high divergence of PR-locus haplotypes suggest a history of multiple, diverse and repeated instances of structural mutation events and restricted recombination. Annotation of the haplotypes reveals striking differences in gene content. In particular, a group of glycosyltransferase genes that is present in the susceptible but absent in the resistant haplotype. Moreover, in natural populations, we find that the PR-locus polymorphism is associated with variation in resistance to different P. ramosa genotypes, pointing to the PR-locus polymorphism as being responsible for the matching-allele interactions that have been previously described for this system. Our results conclusively identify a genetic basis for the matching-allele interaction observed in a coevolving host-parasite system and provide a first insight into its molecular basis.

  1. The genetic basis of resistance and matching-allele interactions of a host-parasite system: The Daphnia magna-Pasteuria ramosa model

    PubMed Central

    Fields, Peter D.; Bourgeois, Yann; Du Pasquier, Louis; Ebert, Dieter

    2017-01-01

    Negative frequency-dependent selection (NFDS) is an evolutionary mechanism suggested to govern host-parasite coevolution and the maintenance of genetic diversity at host resistance loci, such as the vertebrate MHC and R-genes in plants. Matching-allele interactions of hosts and parasites that prevent the emergence of host and parasite genotypes that are universally resistant and infective are a genetic mechanism predicted to underpin NFDS. The underlying genetics of matching-allele interactions are unknown even in host-parasite systems with empirical support for coevolution by NFDS, as is the case for the planktonic crustacean Daphnia magna and the bacterial pathogen Pasteuria ramosa. We fine-map one locus associated with D. magna resistance to P. ramosa and genetically characterize two haplotypes of the Pasteuria resistance (PR-) locus using de novo genome and transcriptome sequencing. Sequence comparison of PR-locus haplotypes finds dramatic structural polymorphisms between PR-locus haplotypes including a large portion of each haplotype being composed of non-homologous sequences resulting in haplotypes differing in size by 66 kb. The high divergence of PR-locus haplotypes suggest a history of multiple, diverse and repeated instances of structural mutation events and restricted recombination. Annotation of the haplotypes reveals striking differences in gene content. In particular, a group of glycosyltransferase genes that is present in the susceptible but absent in the resistant haplotype. Moreover, in natural populations, we find that the PR-locus polymorphism is associated with variation in resistance to different P. ramosa genotypes, pointing to the PR-locus polymorphism as being responsible for the matching-allele interactions that have been previously described for this system. Our results conclusively identify a genetic basis for the matching-allele interaction observed in a coevolving host-parasite system and provide a first insight into its molecular basis

  2. Naturally selected hepatitis C virus polymorphisms confer broad neutralizing antibody resistance

    PubMed Central

    Bailey, Justin R.; Wasilewski, Lisa N.; Snider, Anna E.; El-Diwany, Ramy; Osburn, William O.; Keck, Zhenyong; Foung, Steven K.H.; Ray, Stuart C.

    2014-01-01

    For hepatitis C virus (HCV) and other highly variable viruses, broadly neutralizing mAbs are an important guide for vaccine development. The development of resistance to anti-HCV mAbs is poorly understood, in part due to a lack of neutralization testing against diverse, representative panels of HCV variants. Here, we developed a neutralization panel expressing diverse, naturally occurring HCV envelopes (E1E2s) and used this panel to characterize neutralizing breadth and resistance mechanisms of 18 previously described broadly neutralizing anti-HCV human mAbs. The observed mAb resistance could not be attributed to polymorphisms in E1E2 at known mAb-binding residues. Additionally, hierarchical clustering analysis of neutralization resistance patterns revealed relationships between mAbs that were not predicted by prior epitope mapping, identifying 3 distinct neutralization clusters. Using this clustering analysis and envelope sequence data, we identified polymorphisms in E2 that confer resistance to multiple broadly neutralizing mAbs. These polymorphisms, which are not at mAb contact residues, also conferred resistance to neutralization by plasma from HCV-infected subjects. Together, our method of neutralization clustering with sequence analysis reveals that polymorphisms at noncontact residues may be a major immune evasion mechanism for HCV, facilitating viral persistence and presenting a challenge for HCV vaccine development. PMID:25500884

  3. Bacterial glyphosate resistance conferred by overexpression of an E. coli membrane efflux transporter.

    PubMed

    Staub, Jeffrey M; Brand, Leslie; Tran, Minhtien; Kong, Yifei; Rogers, Stephen G

    2012-04-01

    Glyphosate herbicide-resistant crop plants, introduced commercially in 1994, now represent approximately 85% of the land area devoted to transgenic crops. Herbicide resistance in commercial glyphosate-resistant crops is due to expression of a variant form of a bacterial 5-enolpyruvylshikimate-3-phosphate synthase with a significantly decreased binding affinity for glyphosate at the target site of the enzyme. As a result of widespread and recurrent glyphosate use, often as the only herbicide used for weed management, increasing numbers of weedy species have evolved resistance to glyphosate. Weed resistance is most often due to changes in herbicide translocation patterns, presumed to be through the activity of an as yet unidentified membrane transporter in plants. To provide insight into glyphosate resistance mechanisms and identify a potential glyphosate transporter, we screened Escherichia coli genomic DNA for alternate sources of glyphosate resistance genes. Our search identified a single non-target gene that, when overexpressed in E. coli and Pseudomonas, confers high-level glyphosate resistance. The gene, yhhS, encodes a predicted membrane transporter of the major facilitator superfamily involved in drug efflux. We report here that an alternative mode of glyphosate resistance in E. coli is due to reduced accumulation of glyphosate in cells that overexpress this membrane transporter and discuss the implications for potential alternative resistance mechanisms in other organisms such as plants.

  4. Intracrine androgens and AKR1C3 activation confer resistance to enzalutamide in prostate cancer

    PubMed Central

    Liu, Chengfei; Lou, Wei; Zhu, Yezi; Yang, Joy C.; Nadiminty, Nagalakshmi; Gaikwad, Nilesh W.; Evans, Christopher P.; Gao, Allen C.

    2015-01-01

    The introduction of enzalutamide and abiraterone has led to improvement in the treatment of metastatic castration-resistant prostate cancer (mCRPC). However, acquired resistance to enzalutamide and abiraterone therapies frequently develops within a short period in many patients. In the present study, we developed enzalutamide resistant prostate cancer cells in an effort to understand the mechanisms of resistance. Global gene expression analysis showed that steroid biosynthesis pathway is activated in enzalutamide resistant prostate cancer cells. One of the crucial steroidogenic enzymes, AKR1C3, was significantly elevated in enzalutamide resistant cells. In addition, AKR1C3 is highly expressed in metastatic and recurrent prostate cancer and in enzalutamide resistant prostate xenograft tumors. Liquid Chromatography-Mass Spectrometry (LC-MS) analysis of the steroid metabolites revealed that androgen precursors such as cholesterol, DHEA and progesterone, as well as androgens are highly up regulated in enzalutamide resistant prostate cancer cells compared to the parental cells. Knock down of AKR1C3 expression by shRNA or inhibition of AKR1C3 enzymatic activity by indomethacin resensitized enzalutamide resistant prostate cancer cells to enzalutamide treatment both in vitro and in vivo. In contrast, overexpression of AKR1C3 confers resistance to enzalutamide. Furthermore, the combination of indomethacin and enzalutamide resulted in significant inhibition of enzalutamide-resistant tumor growth. These results suggest that AKR1C3 activation is a critical resistance mechanism associated with enzalutamide resistance, targeting intracrine androgens and AKR1C3 will overcome enzalutamide resistance and improve survival of advanced prostate cancer patients. PMID:25649766

  5. Organic cation transporter 6 directly confers resistance to anticancer platinum drugs

    PubMed Central

    Oguri, Tetsuya; Kunii, Eiji; Fukuda, Satoshi; Sone, Kazuki; Uemura, Takehiro; Takakuwa, Osamu; Kanemitsu, Yoshihiro; Ohkubo, Hirotsugu; Takemura, Masaya; Maeno, Ken; Ito, Yutaka; Niimi, Akio

    2016-01-01

    Organic cation transporters (OCTs) of the solute carrier family 22 have a critical role in the cellular uptake of anticancer platinum drugs. Recently, we found that a decreased OCT6 expression is associated with a reduced intracellular uptake of cisplatin (CDDP), and concomitant resistance to CDDP. In the present study, we examined whether OCTs directly confer resistance to another platinum drug, oxaliplatin (L-OHP). To address this, we used parental lung cancer cell lines, PC-14 and SBC3; L-OHP-resistant sublines, PC-14/L-OHP and SBC3/L-OHP; and one CDDP-resistant subline PC-14/CDDP, to examine the relationships between the expression of OCTs and intracellular platinum drug concentration or platinum drug resistance. The two L-OHP-resistant sublines showed cross resistance to CDDP and L-OHP, and a decreased expression of OCT6. The intracellular accumulation of L-OHP in PC-14/L-OHP cells was reduced compared with the parental cells. The findings suggested that a reduced OCT6 expression confers platinum drug resistance in the sublines by decreasing the uptake of platinum drugs. Using the PC-14/CDDP cell line engineered to overexpress OCT6, we confirmed that the intracellular L-OHP concentration was increased concomitantly with OCT6 overexpression compared with the parental cell line. Additionally, OCT6 was expressed in a screening panel of lung and colon cancer tissues and matched normal control tissues. Taken together with the previous results, the present findings indicate that OCT6 is directly involved in platinum drug resistance by mediating platinum drug uptake in cancer cells. PMID:27882231

  6. Vitamin B3 confers resistance to sulfa drugs in Saccharomyces cerevisiae.

    PubMed

    Kornfeld, Olga; Nichols, Brian P

    2005-10-01

    Sulfa drugs are ubiquitous antibiotics used to treat bacterial infections and diseases caused by eukaryotes, such as Pneumocystis carinii, the leading cause of pneumonia (PCP) in HIV patients. A daily regimen of sulfonamides and multivitamins including vitamin B3 is also recommended for persons with HIV. We show that exogenous vitamin B3 (nicotinate) confers resistance to sulfa drugs in Saccharomyces cerevisiae, a model for P. carinii. We propose a model of metabolic rerouting in which increased nicotinate leads to increased intracellular concentration of p-aminobenzoate, thus leading to sulfonamide resistance.

  7. K13-propeller mutations confer artemisinin resistance in Plasmodium falciparum clinical isolates

    PubMed Central

    Straimer, Judith; Gnädig, Nina F.; Witkowski, Benoit; Amaratunga, Chanaki; Duru, Valentine; Ramadani, Arba Pramundita; Dacheux, Mélanie; Khim, Nimol; Zhang, Lei; Lam, Stephen; Gregory, Philip D.; Urnov, Fyodor D.; Mercereau-Puijalon, Odile; Benoit-Vical, Françoise; Fairhurst, Rick M.; Ménard, Didier; Fidock, David A.

    2015-01-01

    The emergence of artemisinin resistance in Southeast Asia imperils efforts to reduce the global malaria burden. We genetically modified the Plasmodium falciparum K13 locus using zinc-finger nucleases and measured ring-stage survival rates after drug exposure in vitro; these rates correlate with parasite clearance half-lives in artemisinin-treated patients. With isolates from Cambodia, where resistance first emerged, survival rates decreased from 13 to 49% to 0.3 to 2.4% after the removal of K13 mutations. Conversely, survival rates in wild-type parasites increased from ≤0.6% to 2 to 29% after the insertion of K13 mutations. These mutations conferred elevated resistance to recent Cambodian isolates compared with that of reference lines, suggesting a contemporary contribution of additional genetic factors. Our data provide a conclusive rationale for worldwide K13-propeller sequencing to identify and eliminate artemisinin-resistant parasites. PMID:25502314

  8. Rpi-vnt1.1, a Tm-2(2) homolog from Solanum venturii, confers resistance to potato late blight.

    PubMed

    Foster, Simon J; Park, Tae-Ho; Pel, Mathieu; Brigneti, Gianinna; Sliwka, Jadwiga; Jagger, Luke; van der Vossen, Edwin; Jones, Jonathan D G

    2009-05-01

    Despite the efforts of breeders and the extensive use of fungicide control measures, late blight still remains a major threat to potato cultivation worldwide. The introduction of genetic resistance into cultivated potato is considered a valuable method to achieve durable resistance to late blight. Here, we report the identification and cloning of Rpi-vnt1.1, a previously uncharacterized late-blight resistance gene from Solanum venturii. The gene was identified by a classical genetic and physical mapping approach and encodes a coiled-coil nucleotide-binding leucine-rich repeat protein with high similarity to Tm-2(2) from S. lycopersicum which confers resistance against Tomato mosaic virus. Transgenic potato and tomato plants carrying Rpi-vnt1.1 were shown to be resistant to Phytophthora infestans. Of 11 P. infestans isolates tested, only isolate EC1 from Ecuador was able to overcome Rpi-vnt1.1 and cause disease on the inoculated plants. Alleles of Rpi-vnt1.1 (Rpi-vnt1.2 and Rpi-vnt1.3) that differed by only a few nucleotides were found in other late-blight-resistant accessions of S. venturii. The late blight resistance gene Rpi-phu1 from S. phureja is shown here to be identical to Rpi-vnt1.1, suggesting either that this strong resistance gene has been maintained since a common ancestor, due to selection pressure for blight resistance, or that genetic exchange between S. venturii and S. phureja has occurred at some time.

  9. Multidrug resistance protein 1 (ABCC1) confers resistance to arsenic compounds in human myeloid leukemic HL-60 cells.

    PubMed

    Xu, Shi; Zhang, Yan Fang; Carew, Micheal W; Hao, Wen Hui; Loo, Jacky Fong Chuen; Naranmandura, Hua; Le, X Chris

    2013-06-01

    Arsenic trioxide (As(2)O(3)) is established as one of the most effective drugs for treatment of patients with acute promyelocytic leukemia, as well as other types of malignant tumors. However, HL-60 cells are resistant to As(2)O(3), and little is known about the underlying resistance mechanism for As(2)O(3) and its biomethylation products, namely, monomethylarsonous acid (MMA(III)) on the treatment of tumors. In the present study, we investigated the molecular mechanisms underlying iAs(III) and its intermediate metabolite MMA(III)-induced anticancer effects in the HL-60 cells. Here, we show that the HL-60 cells exhibit resistance to inorganic iAs(III) (IC(50) = 10 μM), but are relatively sensitive to its intermediate MMA(III) (IC(50) = 3.5 μM). Moreover, we found that the multidrug resistance protein 1 (MRP1), but not MRP2, is expressed in HL-60 cells, which reduced the intracellular arsenic accumulation, and conferred resistance to inorganic iAs(III) and MMA(III). Pretreatment of HL-60 with MK571, an inhibitor of MRP1, significantly increased iAs(III) and MMA(III)-induced cytotoxicity and arsenic accumulations, suggesting that the expression of MRP1/4 may lead to HL-60 cells resistance to trivalent arsenic compounds.

  10. Mitochondrial Haplogroup N9a Confers Resistance against Type 2 Diabetes in Asians

    PubMed Central

    Fuku, Noriyuki; Park, Kyong Soo; Yamada, Yoshiji; Nishigaki, Yutaka; Cho, Young Min; Matsuo, Hitoshi; Segawa, Tomonori; Watanabe, Sachiro; Kato, Kimihiko; Yokoi, Kiyoshi; Nozawa, Yoshinori; Lee, Hong Kyu; Tanaka, Masashi

    2007-01-01

    Because mitochondria play pivotal roles in both insulin secretion from the pancreatic β cells and insulin resistance of skeletal muscles, we performed a large-scale association study to identify mitochondrial haplogroups that may confer resistance against or susceptibility to type 2 diabetes mellitus (T2DM). The study population comprised 2,906 unrelated Japanese individuals, including 1,289 patients with T2DM and 1,617 controls, and 1,365 unrelated Korean individuals, including 732 patients with T2DM and 633 controls. The genotypes for 25 polymorphisms in the coding region of the mitochondrial genome were determined, and the haplotypes were classified into 10 major haplogroups (i.e., F, B, A, N9a, M7a, M7b, G, D4a, D4b, and D5). Multivariate logistic-regression analysis with adjustment for age and sex revealed that the mitochondrial haplogroup N9a was significantly associated with resistance against T2DM (P=.0002) with an odds ratio of 0.55 (95% confidence interval 0.40–0.75). Even in the modern environment, which is often characterized by satiety and physical inactivity, this haplogroup might confer resistance against T2DM. PMID:17273962

  11. Bactobolin Resistance Is Conferred by Mutations in the L2 Ribosomal Protein

    PubMed Central

    Chandler, Josephine R.; Truong, Thao T.; Silva, Patricia M.; Seyedsayamdost, Mohammad R.; Carr, Gavin; Radey, Matthew; Jacobs, Michael A.; Sims, Elizabeth H.; Clardy, Jon; Greenberg, E. Peter

    2012-01-01

    ABSTRACT Burkholderia thailandensis produces a family of polyketide-peptide molecules called bactobolins, some of which are potent antibiotics. We found that growth of B. thailandensis at 30°C versus that at 37°C resulted in increased production of bactobolins. We purified the three most abundant bactobolins and determined their activities against a battery of bacteria and mouse fibroblasts. Two of the three compounds showed strong activities against both bacteria and fibroblasts. The third analog was much less potent in both assays. These results suggested that the target of bactobolins might be conserved across bacteria and mammalian cells. To learn about the mechanism of bactobolin activity, we isolated four spontaneous bactobolin-resistant Bacillus subtilis mutants. We used genomic sequencing technology to show that each of the four resistant variants had mutations in rplB, which codes for the 50S ribosome-associated L2 protein. Ectopic expression of a mutant rplB gene in wild-type B. subtilis conferred bactobolin resistance. Finally, the L2 mutations did not confer resistance to other antibiotics known to interfere with ribosome function. Our data indicate that bactobolins target the L2 protein or a nearby site and that this is not the target of other antibiotics. We presume that the mammalian target of bactobolins involves the eukaryotic homolog of L2 (L8e). PMID:23249812

  12. Co-Occurrence of Two Allelic Variants of CYP51 in Erysiphe necator and Their Correlation with Over-Expression for DMI Resistance

    PubMed Central

    Rallos, Lynn Esther E.; Baudoin, Anton B.

    2016-01-01

    Demethylation inhibitors (DMIs) have been an important tool in the management of grapevine powdery mildew caused by Erysiphe necator. Long-term, intensive use of DMIs has resulted in reduced sensitivity in field populations. To further characterize DMI resistance and understand resistance mechanisms in this pathogen, we investigated the cyp51 sequence of 24 single-spored isolates from Virginia and surrounding states and analyzed gene expression in isolates representing a wide range of sensitivity. Two cyp51 alleles were found with respect to the 136th codon of the predicted EnCYP51 sequence: the wild-type (TAT) and the mutant (TTT), which results in the known Y136F amino acid change. Some isolates possessed both alleles, demonstrating gene duplication or increased gene copy number and possibly a requirement for at least one mutant copy of CYP51 for resistance. Cyp51 was over-expressed 1.4- to 19-fold in Y136F-mutant isolates. However, the Y136F mutation was absent in one isolate with moderate to high resistance factor. Two additional synonymous mutations were detected as well, one of which, A1119C was present only in isolates with high cyp51 expression. Overall, our results indicate that at least two mechanisms, cyp51 over-expression and the known target-site mutation in CYP51, contribute to resistance in E. necator, and may be working in conjunction with each other. PMID:26839970

  13. APOL1 Risk Alleles are Associated with More Severe Arteriosclerosis in Renal Resistance Vessels with Aging and Hypertension.

    PubMed

    Hughson, Michael D; Hoy, Wendy E; Mott, Susan A; Puelles, Victor G; Bertram, John F; Winkler, Cheryl L; Kopp, Jeffrey B

    2016-05-01

    The increased risk of end-stage kidney disease (ESKD) among hypertensive African Americans is partly related to APOL1 allele variants. Hypertension-associated arterionephrosclerosis consists of arteriosclerosis, glomerulosclerosis, and cortical fibrosis. The initial glomerulosclerosis, attributed to preglomerular arteriosclerosis and ischemia, consists of focal global glomerulosclerosis (FGGS), but in biopsy studies, focal segmental glomerulosclerosis (FSGS) is found with progression to ESKD, particularly in African Americans. This is a study of arterionephrosclerosis in successfully APOL1 genotyped autopsy kidney tissue of 159 African Americans (61 no risk alleles, 68 one risk allele, 30 two risk alleles) and 135 whites aged 18-89 years from a general population with no clinical renal disease. Glomerulosclerosis was nearly exclusively FGGS with only three subjects having FSGS-like lesions that were unrelated to APOL1 risk status. For both races, in multivariable analysis, the dependent variables of arteriosclerosis, glomerulosclerosis, and cortical fibrosis were all significantly related to the independent variables of older age (P < 0.001) and hypertension (P < 0.001). A relationship between APOL1 genotype and arteriosclerosis was apparent only after 35 years of age when, for any level of elevated blood pressure, more severe arteriosclerosis was found in the interlobular arteries of 14 subjects with two APOL1 risk alleles when compared to African Americans with none (n = 37, P = 0.02) or one risk alleles (n = 35, P = 0.02). With the limitation of the small number of subjects contributing to the positive results, the findings imply that APOL1 risk alleles recessively augment small vessel arteriosclerosis in conjunction with age and hypertension. FSGS was not a significant finding, indicating that in the early stages of arterionephrosclerosis, the primary pathologic influence of APOL1 genotype is vascular rather than glomerular.

  14. FabH Mutations Confer Resistance to FabF-Directed Antibiotics in Staphylococcus aureus

    PubMed Central

    Parsons, Joshua B.; Yao, Jiangwei; Frank, Matthew W.

    2014-01-01

    Delineating the mechanisms for genetically acquired antibiotic resistance is a robust approach to target validation and anticipates the evolution of clinical drug resistance. This study defines a spectrum of mutations in fabH that render Staphylococcus aureus resistant to multiple natural products known to inhibit the elongation condensing enzyme (FabF) of bacterial type II fatty acid synthesis. Twenty independently isolated clones resistant to platensimycin, platencin, or thiolactomycin were isolated. All mutants selected against one antibiotic were cross-resistant to the other two antibiotics. Mutations were not detected in fabF, but the resistant strains harbored missense mutations in fabH. The altered amino acids clustered in and around the FabH active-site tunnel. The mutant FabH proteins were catalytically compromised based on the low activities of the purified enzymes, a fatty acid-dependent growth phenotype, and elevated expression of the fabHF operon in the mutant strains. Independent manipulation of fabF and fabH expression levels showed that the FabH/FabF activity ratio was a major determinant of antibiotic sensitivity. Missense mutations that reduce FabH activity are sufficient to confer resistance to multiple antibiotics that bind to the FabF acyl-enzyme intermediate in S. aureus. PMID:25403676

  15. Polar flagella rotation in Vibrio parahaemolyticus confers resistance to bacteriophage infection

    PubMed Central

    Zhang, Hui; Li, Lu; Zhao, Zhe; Peng, Daxin; Zhou, Xiaohui

    2016-01-01

    Bacteriophage has been recognized as a novel approach to treat bacterial infectious diseases. However, phage resistance may reduce the efficacy of phage therapy. Here, we described a mechanism of bacterial resistance to phage infections. In Gram-negative enteric pathogen Vibrio parahaemolyticus, we found that polar flagella can reduce the phage infectivity. Deletion of polar flagella, but not the lateral flagella, can dramatically promote the adsorption of phage to the bacteria and enhances the phage infectivity to V. parahaemolyticus, indicating that polar flagella play an inhibitory role in the phage infection. Notably, it is the rotation, not the physical presence, of polar flagella that inhibits the phage infection of V. parahaemolyticus. Strikingly, phage dramatically reduces the virulence of V. parahaemolyticus only when polar flagella were absent both in vitro and in vivo. These results indicated that polar flagella rotation is a previously unidentified mechanism that confers bacteriophage resistance. PMID:27189325

  16. A VSG expression site-associated gene confers resistance to human serum in Trypanosoma rhodesiense.

    PubMed

    Xong, H V; Vanhamme, L; Chamekh, M; Chimfwembe, C E; Van Den Abbeele, J; Pays, A; Van Meirvenne, N; Hamers, R; De Baetselier, P; Pays, E

    1998-12-11

    Infectivity of Trypanosoma brucei rhodesiense to humans is due to its resistance to a lytic factor present in human serum. In the ETat 1 strain this character was associated with antigenic variation, since expression of the ETat 1.10 variant surface glycoprotein was required to generate resistant (R) clones. In addition, in this strain transcription of a gene termed SRA was detected in R clones only. We show that the ETat 1.10 expression site is the one selectively transcribed in R variants. This expression site contains SRA as an expression site-associated gene (ESAG) and is characterized by the deletion of several ESAGs. Transfection of SRA into T.b. brucei was sufficient to confer resistance to human serum, identifying this gene as one of those responsible for T.b. rhodesiense adaptation to humans.

  17. Catabolic pathway for 2-nitroimidazole involves a novel nitrohydrolase that also confers drug resistance.

    PubMed

    Qu, Yi; Spain, Jim C

    2011-04-01

    Antibiotic resistance in pathogens can be mediated by catabolic enzymes thought to originate from soil bacteria, but the physiological functions and evolutionary origins of the enzymes in natural ecosystems are poorly understood. 2-Nitroimidazole (2NI) is a natural antibiotic and an analogue of the synthetic nitroimidazoles used for treatment of tuberculosis, Chagas' disease and cancer. Mycobacterium sp. JS330 was isolated from soil based on its ability to use 2NI as a sole growth substrate. The initial step in the degradation pathway is the hydrolytic denitration of 2NI to produce imidazol-2-one and nitrite. The amino acid sequence of 2NI nitrohydrolase is highly divergent from those of biochemically characterized enzymes, and it confers drug resistance when it is heterologously expressed in Escherichia coli. The unusual enzymatic reaction seems likely to determine the flux of nitroimidazole in natural ecosystems and also represents the discovery of a previously unreported drug resistance mechanism in soil before its identification in clinical situations.

  18. Genetic Architecture of Resistance to Alternaria brassicae in Arabidopsis thaliana: QTL Mapping Reveals Two Major Resistance-Conferring Loci

    PubMed Central

    Rajarammohan, Sivasubramanian; Kumar, Amarendra; Gupta, Vibha; Pental, Deepak; Pradhan, Akshay K.; Kaur, Jagreet

    2017-01-01

    Alternaria brassicae, a necrotrophic fungal pathogen, causes Alternaria blight, one of the most important diseases of oleiferous Brassica crops. The current study utilized Arabidopsis as a model to decipher the genetic architecture of defense against A. brassicae. Significant phenotypic variation that was largely genetically determined was observed among Arabidopsis accessions in response to pathogen challenge. Three biparental mapping populations were developed from three resistant accessions viz. CIBC-5, Ei-2, and Cvi-0 and two susceptible accessions – Gre-0 and Zdr-1 (commonly crossed to CIBC-5 and Ei-2). A total of six quantitative trait locus (QTLs) governing resistance to A. brassicae were identified, five of which were population-specific while one QTL was common between all the three mapping populations. Interestingly, the common QTL had varying phenotypic contributions in different populations, which can be attributed to the genetic background of the parental accessions. The presence of both common and population-specific QTLs indicate that resistance to A. brassicae is quantitative, and that different genes may mediate resistance to the pathogen in different accessions. Two of the QTLs had moderate-to-large effects, one of which explained nearly 50% of the variation. The large effect QTLs may therefore contain genes that could play a significant role in conferring resistance even in heterologous hosts. PMID:28286515

  19. Distinct detoxification mechanisms confer resistance to mesotrione and atrazine in a population of waterhemp.

    PubMed

    Ma, Rong; Kaundun, Shiv S; Tranel, Patrick J; Riggins, Chance W; McGinness, Daniel L; Hager, Aaron G; Hawkes, Tim; McIndoe, Eddie; Riechers, Dean E

    2013-09-01

    Previous research reported the first case of resistance to mesotrione and other 4-hydroxyphenylpyruvate dioxygenase (HPPD) herbicides in a waterhemp (Amaranthus tuberculatus) population designated MCR (for McLean County mesotrione- and atrazine-resistant). Herein, experiments were conducted to determine if target site or nontarget site mechanisms confer mesotrione resistance in MCR. Additionally, the basis for atrazine resistance was investigated in MCR and an atrazine-resistant but mesotrione-sensitive population (ACR for Adams County mesotrione-sensitive but atrazine-resistant). A standard sensitive population (WCS for Wayne County herbicide-sensitive) was also used for comparison. Mesotrione resistance was not due to an alteration in HPPD sequence, HPPD expression, or reduced herbicide absorption. Metabolism studies using whole plants and excised leaves revealed that the time for 50% of absorbed mesotrione to degrade in MCR was significantly shorter than in ACR and WCS, which correlated with previous phenotypic responses to mesotrione and the quantity of the metabolite 4-hydroxy-mesotrione in excised leaves. The cytochrome P450 monooxygenase inhibitors malathion and tetcyclacis significantly reduced mesotrione metabolism in MCR and corn (Zea mays) excised leaves but not in ACR. Furthermore, malathion increased mesotrione activity in MCR seedlings in greenhouse studies. These results indicate that enhanced oxidative metabolism contributes significantly to mesotrione resistance in MCR. Sequence analysis of atrazine-resistant (MCR and ACR) and atrazine-sensitive (WCS) waterhemp populations detected no differences in the psbA gene. The times for 50% of absorbed atrazine to degrade in corn, MCR, and ACR leaves were shorter than in WCS, and a polar metabolite of atrazine was detected in corn, MCR, and ACR that cochromatographed with a synthetic atrazine-glutathione conjugate. Thus, elevated rates of metabolism via distinct detoxification mechanisms contribute to

  20. MicroRNA-221/222 confers breast cancer fulvestrant resistance by regulating multiple signaling pathways.

    PubMed

    Rao, X; Di Leva, G; Li, M; Fang, F; Devlin, C; Hartman-Frey, C; Burow, M E; Ivan, M; Croce, C M; Nephew, K P

    2011-03-03

    Fulvestrant is a selective estrogen receptor downregulator (SERD) and highly effective antagonist to hormone-sensitive breast cancers following failure of previous tamoxifen or aromatase inhibitor therapies. However, after prolonged fulvestrant therapy, acquired resistance eventually occurs in the majority of breast cancer patients, due to poorly understood mechanisms. To examine a possible role(s) of aberrantly expressed microRNAs (miRNAs) in acquired fulvestrant resistance, we compared antiestrogen-resistant and -sensitive breast cancer cells, revealing the overexpression of miR-221/222 in the SERD-resistant cell lines. Fulvestrant treatment of estradiol (E2)- and fulvestrant-sensitive MCF7 cells resulted in increased expression of endogenous miR-221/222. Ectopic upregulation of miR-221/222 in estrogen receptor-α (ERα)-positive cell lines counteracted the effects of E2 depletion or fulvestrant-induced cell death, thus also conferring hormone-independent growth and fulvestrant resistance. In cells with acquired resistance to fulvestrant, miR-221/222 expression was essential for cell growth and cell cycle progression. To identify possible miR-221/222 targets, miR-221- or miR-222- induced alterations in global gene expression profiles and target gene expression at distinct time points were determined, revealing that miR-221/222 overexpression resulted in deregulation of multiple oncogenic signaling pathways previously associated with drug resistance. Activation of β-catenin by miR-221/222 contributed to estrogen-independent growth and fulvestrant resistance, whereas TGF-β-mediated growth inhibition was repressed by the two miRNAs. This first in-depth investigation into the role of miR-221/222 in acquired fulvestrant resistance, a clinically important problem, demonstrates that these two 'oncomirs' may represent promising therapeutic targets for treating hormone-independent, SERD-resistant breast cancer.

  1. MicroRNA-221/222 confers breast cancer fulvestrant resistance by regulating multiple signaling pathways

    PubMed Central

    Rao, X; Di Leva, G; Li, M; Fang, F; Devlin, C; Hartman-Frey, C; Burow, ME; Ivan, M; Croce, CM; Nephew, KP

    2012-01-01

    Fulvestrant is a selective estrogen receptor downregulator (SERD) and highly effective antagonist to hormone-sensitive breast cancers following failure of previous tamoxifen or aromatase inhibitor therapies. However, after prolonged fulvestrant therapy, acquired resistance eventually occurs in the majority of breast cancer patients, due to poorly understood mechanisms. To examine a possible role(s) of aberrantly expressed microRNAs (miRNAs) in acquired fulvestrant resistance, we compared antiestrogen-resistant and -sensitive breast cancer cells, revealing the over-expression of miR-221/222 in the SERD-resistant cell lines. Fulvestrant treatment of estradiol (E2)- and fulvestrant-sensitive MCF7 cells resulted in increased expression of endogenous miR-221/222. Ectopic upregulation of miR-221/222 in estrogen receptor-α (ERα)-positive cell lines counteracted the effects of E2 depletion or fulvestrant-induced cell death, thus also conferring hormone-independent growth and fulvestrant resistance. In cells with acquired resistance to fulvestrant, miR-221/222 expression was essential for cell growth and cell cycle progression. To identify possible miR-221/222 targets, miR-221- or miR-222- induced alterations in global gene expression profiles and target gene expression at distinct time points were determined, revealing that miR-221/222 overexpression resulted in deregulation of multiple oncogenic signaling pathways previously associated with drug resistance. Activation of β-catenin by miR-221/222 contributed to estrogen-independent growth and fulvestrant resistance, whereas TGF-β-mediated growth inhibition was repressed by the two miRNAs. This first in-depth investigation into the role of miR-221/222 in acquired fulvestrant resistance, a clinically important problem, demonstrates that these two ‘oncomirs’ may represent promising therapeutic targets for treating hormone-independent, SERD-resistant breast cancer. PMID:21057537

  2. Introgression of resistance-conferring ALS mutations in herbicide-resistant weedy rice

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Weedy red rice (Oryza sativa) competes aggressively with rice, reducing yields and grain quality. Clearfield™ rice, a nontransgenic, herbicide-resistant (HR) rice introduced in 2002 to control weedy rice, has resulted in some ALS-resistant weedy rice apparently due to gene flow. Studies were conduct...

  3. Variants of the mannose-binding lectin gene in the Benin population: heterozygosity for the p.G57E allele may confer a selective advantage.

    PubMed

    Dossou-Yovo, Omer Placide; Lapoumeroulie, Claudine; Hauchecorne, Michelle; Zaccaria, Isabelle; Ducrocq, Rolande; Krishnamoorthy, Rajagopal; Rahimy, Mohamed Chérif; Elion, Jacques

    2007-12-01

    Human mannose-binding lectin (MBL) plays an important role in innate immunity. MBL deficiency is associated with mutations in the promoter region and in exon 1 of the MBL2 gene. Such deficiency has been correlated with elevated incidence of infections in infancy and in immunocompromised adults. We determined the distribution profile of the MBL2 gene variants in the general population of Benin (West Africa) and in a vulnerable subset of children with sickle cell disease (SCD) (SS homozygotes). Five hundred forty-two healthy individuals (274 newborns, 268 adults) and 128 patients with SCD (35 newborns, 93 children) were screened for the common variant alleles in the MBL2 secretor haplotype region (exon 1 and promoter). The p.G57E variant allele was the most frequent allele compared to p.G54D (27.5% vs. 1.6%, respectively). The p.R52C allele was not found in this population. There was no difference in allele or genotype frequencies between healthy newborns and newborns with SCD. Alleles associated with MBL deficiency were more frequent in adults than in newborns (69.8% vs. 57.3%, respectively; p = 0.002). This enrichment was exclusively due to an elevated proportion of heterozygotes for the p.G57E allele (47.0% vs. 35.3%, respectively; p = 0.004), supporting a potential selective advantage of this genotype. Our results, compared to those reported in other African countries, support the implication of the MBL2 gene in various major infections in Africa, such as meningitis and tuberculosis in HIV-positive patients.

  4. Variants of the mannose-binding lectin gene in the Benin population: heterozygosity for the p.G57E allele may confer a selective advantage. 2007.

    PubMed

    Dossou-Yovo, Omer Placide; Lapoumeroulie, Claudine; Hauchecorne, Michelle; Zaccaria, Isabelle; Ducrocq, Rolande; Krishnamoorthy, Rajagopal; Rahimy, Mohamed Chérif; Elion, Jacques

    2009-12-01

    Human mannose- binding lectin (MBL) plays an important role in innate immunity. MBL deficiency is associated with mutations in the promoter region and in exon 1 of the MBL2 gene. Such deficiency has been correlated with elevated incidence of infections in infancy and in immunocompromised adults. We determined the distribution profile of the MBL2 gene variants in the general population of Benin (West Africa) and in a vulnerable subset of children with sickle cell disease (SCD) (SS homozygotes). Five hundred forty-two healthy individuals (274 newborns, 268 adults) and 128 patients with SCD (35 newborns, 93 children) were screened for the common variant alleles in the MBL2 secretor haplotype region (exon 1 and promoter). The p.G57E variant allele was the most frequent allele compared to p.G54D (27.5% vs. 1.6%, respectively). The p.R52C allele was not found in this population. There was no difference in allele or genotype frequencies between healthy newborns and newborns with SCD. Alleles associated with MBL deficiency were more frequent in adults than in newborns (69.8% vs. 57.3%, respectively; p=0.002). This enrichment was exclusively due to an elevated proportion of heterozygotes for the p.G57E allele (47.0% vs. 35.3%,respectively; p=0.004), supporting a potential selective advantage of this genotype. Our results, compared to those reported in other African countries, support the implication of the MBL2 gene in various major infections in Africa, such as meningitis and tuberculosis in HIV- positive patients.

  5. The Nematode Resistance Allele at the rhg1 Locus Alters the Proteome and Primary Metabolism of Soybean Roots1[C][W][OA

    PubMed Central

    Afzal, Ahmed J.; Natarajan, Aparna; Saini, Navinder; Iqbal, M. Javed; Geisler, Matt; El Shemy, Hany A.; Mungur, Rajsree; Willmitzer, Lothar; Lightfoot, David A.

    2009-01-01

    Heterodera glycines, the soybean cyst nematode (SCN), causes the most damaging chronic disease of soybean (Glycine max). Host resistance requires the resistance allele at rhg1. Resistance destroys the giant cells created in the plant's roots by the nematodes about 24 to 48 h after commencement of feeding. In addition, 4 to 8 d later, a systemic acquired resistance develops that discourages later infestations. The molecular mechanisms that control the rhg1-mediated resistance response appear to be multigenic and complex, as judged by transcript abundance changes, even in near isogenic lines (NILs). This study aimed to focus on key posttranscriptional changes by identifying proteins and metabolites that were increased in abundance in both resistant and susceptible NILs. Comparisons were made among NILs 10 d after SCN infestation and without SCN infestation. Two-dimensional gel electrophoresis resolved more than 1,000 protein spots on each gel. Only 30 protein spots with a significant (P < 0.05) difference in abundance of 1.5-fold or more were found among the four treatments. The proteins in these spots were picked, trypsin digested, and analyzed using quadrupole time-of-flight tandem mass spectrometry. Protein identifications could be made for 24 of the 30 spots. Four spots contained two proteins, so that 28 distinct proteins were identified. The proteins were grouped into six functional categories. Metabolite analysis by gas chromatography-mass spectrometry identified 131 metabolites, among which 58 were altered by one or more treatment; 28 were involved in primary metabolism. Taken together, the data showed that 17 pathways were altered by the rhg1 alleles. Pathways altered were associated with systemic acquired resistance-like responses, including xenobiotic, phytoalexin, ascorbate, and inositol metabolism, as well as primary metabolisms like amino acid synthesis and glycolysis. The pathways impacted by the rhg1 allelic state and SCN infestation agreed with

  6. SHEA conference on antimicrobial resistance. Society for Healthcare Epidemiology of America.

    PubMed

    Gerding, D N; Martone, W J

    2000-05-01

    Antimicrobial resistance is an increasing problem in healthcare institutions and in the community. Public concern about resistance is also increasing. The issue is broad and complex and not readily addressed by government, industry, or professional societies alone. On October 29-30, 1998, 19 representatives of various professional societies and governmental agencies met under the auspices of the Society for Healthcare Epidemiology of America (SHEA) at Brook Lodge Conference Center in Augusta, Michigan. The purpose of the meeting was to discuss the current status of antimicrobial resistance in the United States and Canada, including present society and governmental efforts to address the problem. Representatives exchanged experiences through presentations and discussions on the first day, then on the second day held a brainstorming session to address future needs and priorities in addressing the resistance problem. It was agreed that a national coordinated effort was needed. As part of this national effort, representatives called for the creation of a National Coalition on Antibiotic Resistance (NCAR) to combat antibiotic resistance through education, research, prevention, and advocacy. Priorities for NCAR were focused in four areas: (1) education of the public and professionals; (2) support of basic and applied research; (3) provision of an information resource and clearinghouse; and (4) advocacy initiatives. At the recommendation of the SHEA Board, discussions with the National Foundation for Infectious Diseases for the joint development of NCAR have begun.

  7. The evolutionary ecology of symbiont-conferred resistance to parasitoids in aphids.

    PubMed

    Vorburger, Christoph

    2014-06-01

    Aphids may harbor a wide variety of facultative bacterial endosymbionts. These symbionts are transmitted maternally with high fidelity and they show horizontal transmission as well, albeit at rates too low to enable infectious spread. Such symbionts need to provide a net fitness benefit to their hosts to persist and spread. Several symbionts have achieved this by evolving the ability to protect their hosts against parasitoids. Reviewing empirical work and some models, I explore the evolutionary ecology of symbiont-conferred resistance to parasitoids in order to understand how defensive symbiont frequencies are maintained at the intermediate levels observed in aphid populations. I further show that defensive symbionts alter the reciprocal selection between aphids and parasitoids by augmenting the heritable variation for resistance, by increasing the genetic specificity of the host-parasitoid interaction, and by inducing environment-dependent trade-offs. These effects are conducive to very dynamic, symbiont-mediated coevolution that is driven by frequency-dependent selection. Finally I argue that defensive symbionts represent a problem for biological control of pest aphids, and I propose to mitigate this problem by exploiting the parasitoids' demonstrated ability to rapidly evolve counteradaptations to symbiont-conferred resistance.

  8. Ectopic expression of RESISTANCE TO POWDERY MILDEW8.1 confers resistance to fungal and oomycete pathogens in Arabidopsis.

    PubMed

    Ma, Xian-Feng; Li, Yan; Sun, Jin-Long; Wang, Ting-Ting; Fan, Jing; Lei, Yang; Huang, Yan-Yan; Xu, Yong-Ju; Zhao, Ji-Qun; Xiao, Shunyuan; Wang, Wen-Ming

    2014-08-01

    Broad-spectrum disease resistance is a highly valuable trait in plant breeding and attracts special attention in research. The Arabidopsis gene locus RESISTANCE TO POWDERY MILDEW 8 (RPW8) contains two adjacent homologous genes, RPW8.1 and RPW8.2, and confers broad-spectrum resistance to powdery mildew. Remarkably, the RPW8.2 protein is specifically localized to the extrahaustorial membrane (EHM) encasing the feeding structure of powdery mildew whereby RPW8.2 activates haustorium-targeted defenses. Here, we show that ectopic expression of the yellow fluorescent protein (YFP)-tagged RPW8.1 from the native promoter leads to unique cell death lesions and enhances resistance to virulent fungal and oomycete pathogens that cause powdery mildew and downy mildew diseases, respectively. In powdery mildew-infected plants, RPW8.1-YFP accumulates at higher levels in the mesophyll cells underneath the infected epidermal cells where RPW8.2-YFP is mainly expressed. This cell type-preferential protein accumulation pattern largely correlates with that of H(2)O(2) accumulation, suggesting that RPW8.1 may spatially collaborate with RPW8.2 in activation of resistance to powdery mildew. Interestingly, when ectopically expressed from the RPW8.2 promoter, RPW8.1-YFP is also targeted to the EHM of powdery mildew and the transgenic plants display resistance to both powdery mildew and downy mildew. Using YFP as a reporter, we further reveal that the RPW8.1 promoter is constitutively active but induced to higher levels in cells at the infection site, whereas the RPW8.2 promoter is activated specifically in cells at the infection site. Taken together, our results suggest that RPW8.1 (and its promoter) is functionally distinct from RPW8.2 and may have a higher potential in engineering broad-spectrum resistance in plants.

  9. Stochastic expression of a multiple antibiotic resistance activator confers transient resistance in single cells.

    PubMed

    El Meouche, Imane; Siu, Yik; Dunlop, Mary J

    2016-01-13

    Transient resistance can allow microorganisms to temporarily survive lethal concentrations of antibiotics. This can be accomplished through stochastic mechanisms, where individual cells within a population display diverse phenotypes to hedge against the appearance of an antibiotic. To date, research on transient stochastic resistance has focused primarily on mechanisms where a subpopulation of cells enters a dormant, drug-tolerant state. However, a fundamental question is whether stochastic gene expression can also generate variable resistance levels among growing cells in a population. We hypothesized that stochastic expression of antibiotic-inducible resistance mechanisms might play such a role. To investigate this, we focused on a prototypical example of such a system: the multiple antibiotic resistance activator MarA. Previous studies have shown that induction of MarA can lead to a multidrug resistant phenotype at the population level. We asked whether MarA expression also has a stochastic component, even when uninduced. Time lapse microscopy showed that isogenic cells express heterogeneous, dynamic levels of MarA, which were correlated with transient antibiotic survival. This finding has important clinical implications, as stochastic expression of resistance genes may be widespread, allowing populations to hedge against the sudden appearance of an antibiotic.

  10. Precisely mapping a major gene conferring resistance to Hessian fly in bread wheat using genotyping-by-sequencing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background One of the reasons hard red winter wheat cultivar ‘Duster’ (PI 644016) is widely grown in the southern Great Plains is that it confers a consistently high level of resistance to biotype GP of Hessian fly (Hf). However, little is known about the genetic mechanism underlying Hf resistance i...

  11. Antibiotic Resistance Surveillance and Control in the Mediterranean region: report of the ARMed Consensus Conference.

    PubMed

    Borg, Michael A; Cookson, Barry D; Zarb, Peter; Scicluna, Elizabeth A

    2009-10-22

    Antimicrobial resistance has become a global threat to effective health care delivery. This is particularly the case within the Mediterranean region, where data from recent studies suggests the situation to be particularly acute. A better knowledge base, as well as a collaborative effort, is therefore required to address this ever increasing challenge to effective patient care. Over its four-year period, the Antibiotic Resistance Surveillance and Control in the Mediterranean Region (ARMed) project investigated the epidemiology of antimicrobial resistance, as well as its contributory factors, in a number of countries in the southern and eastern Mediterranean region through the collection of comparable and validated data. The project culminated in a consensus conference held in Malta in November 2006. The conference provided a forum for expert delegates to agree on a number of priority strategic recommendations that would be relevant to resistance containment efforts in the region. There was general agreement on the need for surveillance and audit to underpin any intervention to tackle antimicrobial resistance, both to monitor changing epidemiological trends in critical pathogens as well as to identify antibiotic consumption practices and effectiveness of prevention and control of health care associated infections. In addition, the importance to convey these data to key users was also stressed in all workshops, as was better education and training of health care workers. The recommendations also made it clear that ownership of the problem needs to be improved throughout the region and that resources, both financial as well as human, must be allocated by the respective policy makers in order to combat it.

  12. The Arabidopsis NPR1 gene confers broad-spectrum disease resistance in strawberry.

    PubMed

    Silva, Katchen Julliany P; Brunings, Asha; Peres, Natalia A; Mou, Zhonglin; Folta, Kevin M

    2015-08-01

    Although strawberry is an economically important fruit crop worldwide, production of strawberry is limited by its susceptibility to a wide range of pathogens and the lack of major commercial cultivars with high levels of resistance to multiple pathogens. The objective of this study is to ectopically express the Arabidopsis thaliana NPR1 gene (AtNPR1) in the diploid strawberry Fragaria vesca L. and to test transgenic plants for disease resistance. AtNPR1 is a key positive regulator of the long-lasting broad-spectrum resistance known as systemic acquired resistance (SAR) and has been shown to confer resistance to a number of pathogens when overexpressed in Arabidopsis or ectopically expressed in several crop species. We show that ectopic expression of AtNPR1 in strawberry increases resistance to anthracnose, powdery mildew, and angular leaf spot, which are caused by different fungal or bacterial pathogens. The increased resistance is related to the relative expression levels of AtNPR1 in the transgenic plants. In contrast to Arabidopsis plants overexpressing AtNPR1, which grow normally and do not constitutively express defense genes, the strawberry transgenic plants are shorter than non-transformed controls, and most of them fail to produce runners and fruits. Consistently, most of the transgenic lines constitutively express the defense gene FvPR5, suggesting that the SAR activation mechanisms in strawberry and Arabidopsis are different. Nevertheless, our results indicate that overexpression of AtNPR1 holds the potential for generation of broad-spectrum disease resistance in strawberry.

  13. A mutant beta-tubulin confers resistance to the action of benzimidazole-carbamate microtubule inhibitors both in vivo and in vitro.

    PubMed

    Foster, K E; Burland, T G; Gull, K

    1987-03-16

    The mutant BEN210 of Physarum polycephalum is highly resistant to a number of benzimidazole carbamate agents, including methylbenzimidazole-2-yl-carbamate and parbendazole. The resistance is conferred by the benD210 mutation in a structural gene for beta-tubulin. This mutant allele encodes a beta-tubulin with novel electrophoretic mobility. We have used this strain to determine whether the mutant beta-tubulin is used in microtubules and whether this usage permits microtubule polymerisation in the presence of drugs both in vivo and in vitro. In vitro assembly studies of tubulin purified from the mutant strain have shown that microtubules are formed both in the absence of drugs and in all drug concentrations tested (up to 50 microM parbendazole). In contrast, the assembly of microtubules from wild-type tubulin in vitro is totally inhibited by 2-5 microM parbendazole. Thus the resistance of BEN210 to parbendazole observed in vivo has been reproduced in vitro using tubulin purified from the mutant strain. Electrophoretic analysis of the microtubules formed in vitro has shown that both the wild-type and the mutant beta-tubulin are incorporated into the microtubules and that the proportion of mutant to wild-type beta-tubulin appears to remain constant with increasing drug concentration. This is the first demonstration of a single mutation in a tubulin structural gene causing an altered function of the gene product in vitro.

  14. Pathogens of Bovine Respiratory Disease in North American Feedlots Conferring Multidrug Resistance via Integrative Conjugative Elements

    PubMed Central

    Klima, Cassidy L.; Zaheer, Rahat; Cook, Shaun R.; Booker, Calvin W.; Hendrick, Steve

    2014-01-01

    In this study, we determined the prevalence of bovine respiratory disease (BRD)-associated viral and bacterial pathogens in cattle and characterized the genetic profiles, antimicrobial susceptibilities, and nature of antimicrobial resistance determinants in collected bacteria. Nasopharyngeal swab and lung tissue samples from 68 BRD mortalities in Alberta, Canada (n = 42), Texas (n = 6), and Nebraska (n = 20) were screened using PCR for bovine viral diarrhea virus (BVDV), bovine respiratory syncytial virus, bovine herpesvirus 1, parainfluenza type 3 virus, Mycoplasma bovis, Mannheimia haemolytica, Pasteurella multocida, and Histophilus somni. Excepting bovine herpesvirus 1, all agents were detected. M. haemolytica (91%) and BVDV (69%) were the most prevalent, with cooccurrence in 63% of the cattle. Isolates of M. haemolytica (n = 55), P. multocida (n = 8), and H. somni (n = 10) from lungs were also collected. Among M. haemolytica isolates, a clonal subpopulation (n = 8) was obtained from a Nebraskan feedlot. All three bacterial pathogens exhibited a high rate of antimicrobial resistance, with 45% exhibiting resistance to three or more antimicrobials. M. haemolytica (n = 18), P. multocida (n = 3), and H. somni (n = 3) from Texas and Nebraska possessed integrative conjugative elements (ICE) that conferred resistance for up to seven different antimicrobial classes. ICE were shown to be transferred via conjugation from P. multocida to Escherichia coli and from M. haemolytica and H. somni to P. multocida. ICE-mediated multidrug-resistant profiles of bacterial BRD pathogens could be a major detriment to many of the therapeutic antimicrobial strategies currently used to control BRD. PMID:24478472

  15. MicroRNA-520g Confers Drug Resistance by Regulating p21 Expression in Colorectal Cancer*

    PubMed Central

    Zhang, Yang; Geng, Liying; Talmon, Geoffrey; Wang, Jing

    2015-01-01

    Development of drug resistance is one of the major causes of colorectal cancer recurrence, yet mechanistic understanding and therapeutic options remain limited. Here, we show that expression of microRNA (miR)-520g is correlated with drug resistance of colon cancer cells. Ectopic expression of miR-520g conferred resistance to 5-fluorouracil (5-FU)- or oxaliplatin-induced apoptosis in vitro and reduced the effectiveness of 5-FU in the inhibition of tumor growth in a mouse xenograft model in vivo. Further studies indicated that miR-520g mediated drug resistance through down-regulation of p21 expression. Moreover, p53 suppressed miR-520g expression, and deletion of p53 up-regulated miR-520g expression. Inhibition of miR-520g in p53−/− cells increased their sensitivity to 5-FU treatment. Importantly, studies of patient samples indicated that expression of miR-520g correlated with chemoresistance in colorectal cancer. These findings indicate that the p53/miR-520g/p21 signaling axis plays an important role in the response of colorectal cancer to chemotherapy. A major implication of our studies is that inhibition of miR-520g or restoration of p21 expression may have considerable therapeutic potential to overcome drug resistance in colorectal cancer patients, especially in those with mutant p53. PMID:25616665

  16. Herbicide resistance in Aster squamatus conferred by a less sensitive form of acetolactate synthase.

    PubMed

    Osuna, Maria D; Fischer, Albert J; De Prado, Rafael

    2003-11-01

    A biotype of Aster squamatus (Sprengel) Hieronymus with suspected resistance to the ALS-inhibiting herbicide imazapyr was detected in a chicken farm in the province of Seville, Spain, which had been treated once a year with imazapyr for 10 years. Resistance to imazapyr in this biotype was studied using dose-response experiments, absorption and translocation assays, metabolism studies and ALS activity assays. The rate of imazapyr required to inhibit A squamatus growth by 50% (ED50) was 15 times higher for the R (resistant) than for the S (susceptible) biotype. Cross-resistance existed for the ALS-inhibitors imazamox, imazethapyr, amidosulfuron, nicosulfuron, rimsulfuron, triasulfuron and tribenuron, but not for bensulfuron. Control of A squamatus using alternative herbicides was poor with clopyralid, intermediate with quinclorac, amitrole and MCPA, and excellent with 2,4-D, glufosinate and glyphosate. Absorption of [14C]imazapyr increased over time for both the R and S biotypes, and translocation from the treated leaf to shoots and roots was similar in both biotypes, with most of the radioactivity remaining in the treated leaf. No metabolites of imazapyr were detected in either biotype. Sensitivity of the ALS enzyme (target site) to imazapyr was lower for the R biotype (I50(R) = 4.28 x I50(S)). The mechanism of imazapyr resistance in this R biotype appears to be an altered ALS conferring decreased sensitivity to imazapyr at the whole-plant level.

  17. An antibody that confers plant disease resistance targets a membrane-bound glyoxal oxidase in Fusarium.

    PubMed

    Song, Xiu-Shi; Xing, Shu; Li, He-Ping; Zhang, Jing-Bo; Qu, Bo; Jiang, Jin-He; Fan, Chao; Yang, Peng; Liu, Jin-Long; Hu, Zu-Quan; Xue, Sheng; Liao, Yu-Cai

    2016-05-01

    Plant germplasm resources with natural resistance against globally important toxigenic Fusarium are inadequate. CWP2, a Fusarium genus-specific antibody, confers durable resistance to different Fusarium pathogens that infect cereals and other crops, producing mycotoxins. However, the nature of the CWP2 target is not known. Thus, investigation of the gene coding for the CWP2 antibody target will likely provide critical insights into the mechanism underlying the resistance mediated by this disease-resistance antibody. Immunoblots and mass spectrometry analysis of two-dimensional electrophoresis gels containing cell wall proteins from Fusarium graminearum (Fg) revealed that a glyoxal oxidase (GLX) is the CWP2 antigen. Cellular localization studies showed that GLX is localized to the plasma membrane. This GLX efficiently catalyzes hydrogen peroxide production; this enzymatic activity was specifically inhibited by the CWP2 antibody. GLX-deletion strains of Fg, F. verticillioides (Fv) and F. oxysporum had significantly reduced virulence on plants. The GLX-deletion Fg and Fv strains had markedly reduced mycotoxin accumulation, and the expression of key genes in mycotoxin metabolism was downregulated. This study reveals a single gene-encoded and highly conserved cellular surface antigen that is specifically recognized by the disease-resistance antibody CWP2 and regulates both virulence and mycotoxin biosynthesis in Fusarium species.

  18. Rewiring mitogen-activated protein kinase cascade by positive feedback confers potato blight resistance.

    PubMed

    Yamamizo, Chihiro; Kuchimura, Kazuo; Kobayashi, Akira; Katou, Shinpei; Kawakita, Kazuhito; Jones, Jonathan D G; Doke, Noriyuki; Yoshioka, Hirofumi

    2006-02-01

    Late blight, caused by the notorious pathogen Phytophthora infestans, is a devastating disease of potato (Solanum tuberosum) and tomato (Solanum lycopersicum), and during the 1840s caused the Irish potato famine and over one million fatalities. Currently, grown potato cultivars lack adequate blight tolerance. Earlier cultivars bred for resistance used disease resistance genes that confer immunity only to some strains of the pathogen harboring corresponding avirulence gene. Specific resistance gene-mediated immunity and chemical controls are rapidly overcome in the field when new pathogen races arise through mutation, recombination, or migration from elsewhere. A mitogen-activated protein kinase (MAPK) cascade plays a pivotal role in plant innate immunity. Here we show that the transgenic potato plants that carry a constitutively active form of MAPK kinase driven by a pathogen-inducible promoter of potato showed high resistance to early blight pathogen Alternaria solani as well as P. infestans. The pathogen attack provoked defense-related MAPK activation followed by induction of NADPH oxidase gene expression, which is implicated in reactive oxygen species production, and resulted in hypersensitive response-like phenotype. We propose that enhancing disease resistance through altered regulation of plant defense mechanisms should be more durable and publicly acceptable than engineering overexpression of antimicrobial proteins.

  19. Pathogens of bovine respiratory disease in North American feedlots conferring multidrug resistance via integrative conjugative elements.

    PubMed

    Klima, Cassidy L; Zaheer, Rahat; Cook, Shaun R; Booker, Calvin W; Hendrick, Steve; Alexander, Trevor W; McAllister, Tim A

    2014-02-01

    In this study, we determined the prevalence of bovine respiratory disease (BRD)-associated viral and bacterial pathogens in cattle and characterized the genetic profiles, antimicrobial susceptibilities, and nature of antimicrobial resistance determinants in collected bacteria. Nasopharyngeal swab and lung tissue samples from 68 BRD mortalities in Alberta, Canada (n = 42), Texas (n = 6), and Nebraska (n = 20) were screened using PCR for bovine viral diarrhea virus (BVDV), bovine respiratory syncytial virus, bovine herpesvirus 1, parainfluenza type 3 virus, Mycoplasma bovis, Mannheimia haemolytica, Pasteurella multocida, and Histophilus somni. Excepting bovine herpesvirus 1, all agents were detected. M. haemolytica (91%) and BVDV (69%) were the most prevalent, with cooccurrence in 63% of the cattle. Isolates of M. haemolytica (n = 55), P. multocida (n = 8), and H. somni (n = 10) from lungs were also collected. Among M. haemolytica isolates, a clonal subpopulation (n = 8) was obtained from a Nebraskan feedlot. All three bacterial pathogens exhibited a high rate of antimicrobial resistance, with 45% exhibiting resistance to three or more antimicrobials. M. haemolytica (n = 18), P. multocida (n = 3), and H. somni (n = 3) from Texas and Nebraska possessed integrative conjugative elements (ICE) that conferred resistance for up to seven different antimicrobial classes. ICE were shown to be transferred via conjugation from P. multocida to Escherichia coli and from M. haemolytica and H. somni to P. multocida. ICE-mediated multidrug-resistant profiles of bacterial BRD pathogens could be a major detriment to many of the therapeutic antimicrobial strategies currently used to control BRD.

  20. Expression of the Bs2 pepper gene confers resistance to bacterial spot disease in tomato

    PubMed Central

    Tai, Thomas H.; Dahlbeck, Douglas; Clark, Eszter T.; Gajiwala, Paresh; Pasion, Romela; Whalen, Maureen C.; Stall, Robert E.; Staskawicz, Brian J.

    1999-01-01

    The Bs2 resistance gene of pepper specifically recognizes and confers resistance to strains of Xanthomonas campestris pv. vesicatoria that contain the corresponding bacterial avirulence gene, avrBs2. The involvement of avrBs2 in pathogen fitness and its prevalence in many X. campestris pathovars suggests that the Bs2 gene may be durable in the field and provide resistance when introduced into other plant species. Employing a positional cloning strategy, the Bs2 locus was isolated and the gene was identified by coexpression with avrBs2 in an Agrobacterium-mediated transient assay. A single candidate gene, predicted to encode motifs characteristic of the nucleotide binding site–leucine-rich repeat class of resistance genes, was identified. This gene specifically controlled the hypersensitive response when transiently expressed in susceptible pepper and tomato lines and in a nonhost species, Nicotiana benthamiana, and was designated as Bs2. Functional expression of Bs2 in stable transgenic tomatoes supports its use as a source of resistance in other Solanaceous plant species. PMID:10570214

  1. MENA Confers Resistance to Paclitaxel in Triple-Negative Breast Cancer.

    PubMed

    Oudin, Madeleine J; Barbier, Lucie; Schäfer, Claudia; Kosciuk, Tatsiana; Miller, Miles A; Han, Sangyoon; Jonas, Oliver; Lauffenburger, Douglas A; Gertler, Frank B

    2017-01-01

    Taxane therapy remains the standard of care for triple-negative breast cancer. However, high frequencies of recurrence and progression in treated patients indicate that metastatic breast cancer cells can acquire resistance to this drug. The actin regulatory protein MENA and particularly its invasive isoform, MENA(INV), are established drivers of metastasis. MENA(INV) expression is significantly correlated with metastasis and poor outcome in human patients with breast cancer. We investigated whether MENA isoforms might play a role in driving resistance to chemotherapeutics. We find that both MENA and MENA(INV) confer resistance to the taxane paclitaxel, but not to the widely used DNA-damaging agents doxorubicin or cisplatin. Furthermore, paclitaxel treatment does not attenuate growth of MENA(INV)-driven metastatic lesions. Mechanistically, MENA isoform expression alters the ratio of dynamic and stable microtubule populations in paclitaxel-treated cells. MENA expression also increases MAPK signaling in response to paclitaxel treatment. Decreasing ERK phosphorylation by co-treatment with MEK inhibitor restored paclitaxel sensitivity by driving microtubule stabilization in MENA isoform-expressing cells. Our results reveal a novel mechanism of taxane resistance in highly metastatic breast cancer cells and identify a combination therapy to overcome such resistance. Mol Cancer Ther; 16(1); 143-55. ©2016 AACR.

  2. Frequency of spontaneous mutations that confer antibiotic resistance in Chlamydia spp.

    PubMed

    Binet, Rachel; Maurelli, Anthony T

    2005-07-01

    Mutations in rRNA genes (rrn) that confer resistance to ribosomal inhibitors are typically recessive or weakly codominant and have been mostly reported for clinical strains of pathogens possessing only one or two rrn operons, such as Helicobacter pylori and Mycobacterium spp. An analysis of the genome sequences of several members of the Chlamydiaceae revealed that these obligate intracellular bacteria harbor only one or two sets of rRNA genes. To study the contribution of rRNA mutations to the emergence of drug resistance in the Chlamydiaceae, we used the sensitivities of Chlamydia trachomatis L2 (two rrn operons) and Chlamydophila psittaci 6BC (one rrn operon) to the aminoglycoside spectinomycin as a model. Confluent cell monolayers were infected in a plaque assay with about 10(8) wild-type infectious particles and then treated with the antibiotic. After a 2-week incubation time, plaques formed by spontaneous spectinomycin-resistant (Spc(r)) mutants appeared with a frequency of 5 x 10(-5) for C. psittaci 6BC. No Spc(r) mutants were isolated for C. trachomatis L2, although the frequencies of rifampin resistance were in the same range for both strains (i.e., 10(-7)). The risk of emergence of Chlamydia strains resistant to tetracyclines and macrolides, the ribosomal drugs currently used to treat chlamydial infections, is discussed.

  3. Association of the bovine leukocyte antigen major histocompatibility complex class II DRB3*4401 allele with host resistance to the Lone Star tick, Amblyomma americanum.

    PubMed

    Untalan, Pia M; Pruett, John H; Steelman, C Dayton

    2007-04-10

    The MHC of cattle, known as the bovine leukocyte antigen (BoLA) complex, plays an integral role in disease and parasite susceptibility, and immune responsiveness of the host. While susceptibility to tick infestation in cattle is believed to be heritable, genes that may be responsible for the manifestation of this phenotype remain elusive. In an effort to analyze the role that genes within the BoLA complex may play in host resistance to ticks, we have evaluated components of this system within a herd of cattle established at our laboratory that has been phenotyped for ectoparasite susceptibility. Of three microsatellite loci within the BoLA complex analyzed, alleles of two microsatellite loci within the BoLA class IIa cluster (DRB1-118 and DRB3-174) associated with the tick-resistant phenotype, prompting further investigation of gene sequences within the DRB3 region. DRB3 is a class IIa gene, the second exon of which is highly polymorphic since it encodes the antigen recognition site of the DR class II molecule. Analysis of the second exon of the DRB3 gene from the phenotyped calves in our herd revealed a significant association between the DRB3*4401 allele and the tick-resistant phenotype. To our knowledge, this is the first report of a putative association between a class IIa DRB3 sequence and host resistance to the Lone Star tick. Elucidation of the mechanism involved in tick resistance will contribute to improving breeding schemes for parasite resistance, which will be beneficial to the cattle industry.

  4. 4th international conference on tumor progression and therapeutic resistance: meeting report

    PubMed Central

    Prabhu, Varun V; El-Deiry, Wafik S

    2015-01-01

    The fourth international conference on tumor progression and therapeutic resistance organized in association with GTCbio was held in Boston, MA from March 9 to 11, 2014. The meeting attracted a diverse group of experts in the field of cancer biology, therapeutics and medical oncology from academia and industry. The meeting addressed the current challenges in the treatment of cancer including tumor heterogeneity, therapy resistance and metastasis along with the need for improved biomarkers of tumor progression and clinical trial design. Keynote speakers included Clifton Leaf, Editor at Fortune Magazine, Dr. Mina Bissell from the Lawrence Berkeley National Laboratory and Dr. Levi Garraway from the Dana Farber Cancer Institute. The meeting featured cutting edge tools, preclinical models and the latest basic, translational and clinical research findings in the field. PMID:25782066

  5. MicroRNAs suppress NB domain genes in tomato that confer resistance to Fusarium oxysporum.

    PubMed

    Ouyang, Shouqiang; Park, Gyungsoon; Atamian, Hagop S; Han, Cliff S; Stajich, Jason E; Kaloshian, Isgouhi; Borkovich, Katherine A

    2014-10-01

    MicroRNAs (miRNAs) suppress the transcriptional and post-transcriptional expression of genes in plants. Several miRNA families target genes encoding nucleotide-binding site-leucine-rich repeat (NB-LRR) plant innate immune receptors. The fungus Fusarium oxysporum f. sp. lycopersici causes vascular wilt disease in tomato. We explored a role for miRNAs in tomato defense against F. oxysporum using comparative miRNA profiling of susceptible (Moneymaker) and resistant (Motelle) tomato cultivars. slmiR482f and slmiR5300 were repressed during infection of Motelle with F. oxysporum. Two predicted mRNA targets each of slmiR482f and slmiR5300 exhibited increased expression in Motelle and the ability of these four targets to be regulated by the miRNAs was confirmed by co-expression in Nicotiana benthamiana. Silencing of the targets in the resistant Motelle cultivar revealed a role in fungal resistance for all four genes. All four targets encode proteins with full or partial nucleotide-binding (NB) domains. One slmiR5300 target corresponds to tm-2, a susceptible allele of the Tomato Mosaic Virus resistance gene, supporting functions in immunity to a fungal pathogen. The observation that none of the targets correspond to I-2, the only known resistance (R) gene for F. oxysporum in tomato, supports roles for additional R genes in the immune response. Taken together, our findings suggest that Moneymaker is highly susceptible because its potential resistance is insufficiently expressed due to the action of miRNAs.

  6. MicroRNAs Suppress NB Domain Genes in Tomato That Confer Resistance to Fusarium oxysporum

    DOE PAGES

    Ouyang, Shouqiang; Park, Gyungsoon; Atamian, Hagop S.; ...

    2014-10-16

    MicroRNAs (miRNAs) suppress the transcriptional and post-transcriptional expression of genes in plants. Several miRNA families target genes encoding nucleotide-binding site–leucine-rich repeat (NB-LRR) plant innate immune receptors. The fungus Fusarium oxysporum f. sp. lycopersici causes vascular wilt disease in tomato. Here, we explored a role for miRNAs in tomato defense against F. oxysporum using comparative miRNA profiling of susceptible (Moneymaker) and resistant (Motelle) tomato cultivars. slmiR482f and slmiR5300 were repressed during infection of Motelle with F. oxysporum. Two predicted mRNA targets each of slmiR482f and slmiR5300 exhibited increased expression in Motelle and the ability of these four targets to be regulatedmore » by the miRNAs was confirmed by co-expression in Nicotiana benthamiana. Silencing of the targets in the resistant Motelle cultivar revealed a role in fungal resistance for all four genes. All four targets encode proteins with full or partial nucleotide-binding (NB) domains. One slmiR5300 target corresponds to tm-2, a susceptible allele of the Tomato Mosaic Virus resistance gene, supporting functions in immunity to a fungal pathogen. The observation that none of the targets correspond to I-2, the only known resistance (R) gene for F. oxysporum in tomato, supports roles for additional R genes in the immune response. In conclusion, taken together, our findings suggest that Moneymaker is highly susceptible because its potential resistance is insufficiently expressed due to the action of miRNAs.« less

  7. MicroRNAs Suppress NB Domain Genes in Tomato That Confer Resistance to Fusarium oxysporum

    SciTech Connect

    Ouyang, Shouqiang; Park, Gyungsoon; Atamian, Hagop S.; Han, Cliff S.; Stajich, Jason E.; Kaloshian, Isgouhi; Borkovich, Katherine A.

    2014-10-16

    MicroRNAs (miRNAs) suppress the transcriptional and post-transcriptional expression of genes in plants. Several miRNA families target genes encoding nucleotide-binding site–leucine-rich repeat (NB-LRR) plant innate immune receptors. The fungus Fusarium oxysporum f. sp. lycopersici causes vascular wilt disease in tomato. Here, we explored a role for miRNAs in tomato defense against F. oxysporum using comparative miRNA profiling of susceptible (Moneymaker) and resistant (Motelle) tomato cultivars. slmiR482f and slmiR5300 were repressed during infection of Motelle with F. oxysporum. Two predicted mRNA targets each of slmiR482f and slmiR5300 exhibited increased expression in Motelle and the ability of these four targets to be regulated by the miRNAs was confirmed by co-expression in Nicotiana benthamiana. Silencing of the targets in the resistant Motelle cultivar revealed a role in fungal resistance for all four genes. All four targets encode proteins with full or partial nucleotide-binding (NB) domains. One slmiR5300 target corresponds to tm-2, a susceptible allele of the Tomato Mosaic Virus resistance gene, supporting functions in immunity to a fungal pathogen. The observation that none of the targets correspond to I-2, the only known resistance (R) gene for F. oxysporum in tomato, supports roles for additional R genes in the immune response. In conclusion, taken together, our findings suggest that Moneymaker is highly susceptible because its potential resistance is insufficiently expressed due to the action of miRNAs.

  8. Haplotype variation of Glu-D1 locus and the origin of Glu-D1d allele conferring superior end-use qualities in common wheat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In common wheat (Triticum aestivum, AABBDD), the Glu-D1 locus possesses multiple alleles, with Glu-D1a (coding for 1Dx2 and 1Dy12 subunits) and Glu-D1d (encoding 1Dx5 and 1Dy10 subunits) being intensively used in the genetic improvement of end-use qualities. Here, we studied the molecular variatio...

  9. Superbugs and Superdrugs-SMi's 12th annual conference--Overcoming resistance. 17-18 March 2010, London, UK.

    PubMed

    Oni, Adekemi

    2010-05-01

    The 12th Annual Superbugs and Superdrugs conference, held in London, included topics covering new therapeutic developments in the field of antimicrobial research. This conference report highlights selected presentations on antimicrobial peptides, addressing bacterial resistance, and new treatments for bacterial infections. Investigational drugs discussed include DPK-060 (DermaGen AB), DAV-132 (Da Volterra), PF-4287881, PNU-100480 and PF-02538084 (all Pfizer Inc), BAL-30072 (Basilea Pharmaceutica International Ltd) and lanbiotics from Novacta.

  10. Mitochondrial biogenesis in epithelial cancer cells promotes breast cancer tumor growth and confers autophagy resistance.

    PubMed

    Salem, Ahmed F; Whitaker-Menezes, Diana; Howell, Anthony; Sotgia, Federica; Lisanti, Michael P

    2012-11-15

    Here, we set out to test the novel hypothesis that increased mitochondrial biogenesis in epithelial cancer cells would "fuel" enhanced tumor growth. For this purpose, we generated MDA-MB-231 cells (a triple-negative human breast cancer cell line) overexpressing PGC-1α and MitoNEET, which are established molecules that drive mitochondrial biogenesis and increased mitochondrial oxidative phosphorylation (OXPHOS). Interestingly, both PGC-1α and MitoNEET increased the abundance of OXPHOS protein complexes, conferred autophagy resistance under conditions of starvation and increased tumor growth by up to ~3-fold. However, this increase in tumor growth was independent of neo-angiogenesis, as assessed by immunostaining and quantitation of vessel density using CD31 antibodies. Quantitatively similar increases in tumor growth were also observed by overexpression of PGC-1β and POLRMT in MDA-MB-231 cells, which are also responsible for mediating increased mitochondrial biogenesis. Thus, we propose that increased mitochondrial "power" in epithelial cancer cells oncogenically promotes tumor growth by conferring autophagy resistance. As such, PGC-1α, PGC-1β, mitoNEET and POLRMT should all be considered as tumor promoters or "metabolic oncogenes." Our results are consistent with numerous previous clinical studies showing that metformin (a weak mitochondrial "poison") prevents the onset of nearly all types of human cancers in diabetic patients. Therefore, metformin (a complex I inhibitor) and other mitochondrial inhibitors should be developed as novel anticancer therapies, targeting mitochondrial metabolism in cancer cells.

  11. Short-Chain Chromate Ion Transporter Proteins from Bacillus subtilis Confer Chromate Resistance in Escherichia coli▿

    PubMed Central

    Díaz-Magaña, Amada; Aguilar-Barajas, Esther; Moreno-Sánchez, Rafael; Ramírez-Díaz, Martha I.; Riveros-Rosas, Héctor; Vargas, Eréndira; Cervantes, Carlos

    2009-01-01

    Tandem paired genes encoding putative short-chain monodomain protein members of the chromate ion transporter (CHR) superfamily (ywrB and ywrA) were cloned from genomic DNA of Bacillus subtilis strain 168. The transcription of the paired genes, renamed chr3N and chr3C, respectively, was shown to occur via a bicistronic mRNA generated from a promoter upstream of the chr3N gene. The chr3N and chr3C genes conferred chromate resistance when expressed in Escherichia coli strain W3110. The cloned chr3N gene alone did not confer chromate resistance on E. coli, suggesting that both chr3N and chr3C genes are required for function. E. coli cells expressing paired chr3N and chr3C genes demonstrated diminished uptake of chromate compared to that by a vector-only control strain. These results suggest that short-chain CHR proteins form heterodimer transporters which efflux chromate ions from the cytoplasm. PMID:19581367

  12. Inheritance patterns, dominance, stability, and allelism of insecticide resistance and cross-resistance in two colonies of Culex quinquefasciatus (Diptera: Culicidae) selected with cry toxins from Bacillus thuringiensis subsp, israelensis.

    PubMed

    Wirth, Margaret C; Walton, William E; Federici, Brian A

    2010-09-01

    Mendelian crosses were used to analyze the patterns of inheritance of Cry-toxin resistance in two colonies of Culex quinquefasciatus Say larvae resistant to bacterial toxins produced by Bacillus thuringiensis subsp. israelensis de Barjac. Resistance levels exceeded 1000-fold at 95% lethal concentration of the CryllAa-resistant colony (Cq11A). F1 offspring of reciprocal crosses to a susceptible colony revealed autosomal inheritance and offspring were intermediate in resistance to the susceptible and resistant parental lines. Dose-response tests on backcross offspring were consistent with polyfactorial inheritance of resistance toward CryllAa and Cry4Aa + Cry4Ba, whereas cross-resistance toward CryllBa best fit a monofactorial model. Resistance was 600-fold at 95% lethal concentration in the colony selected with Cry4A + Cry4B (Cq4AB). Inheritance of resistance in F1 offspring was autosomal and intermediate to the susceptible and resistant parents. Inheritance of Cry4Aa + Cry4Ba and CryllBa resistance best fit a polyfactorial model in offspring of the Cq4AB backcross, whereas CryllAa-resistance inheritance fit a monofactorial model. Dominance values were calculated at different Cry-toxin concentrations for F, offspring of both resistant colonies; dominance generally decreased as treatment concentration increased. Resistance and cross-resistance remained stable in CqllA and Cq4AB in the absence of insecticide pressure. Allelic complementation tests were complementary and suggested that CqllA and Cq4AB evolved resistance to Cry toxins at common loci. The patterns of cross-resistance suggest cross-recognition of binding moieties by CryllAa, Cry4Aa + Cry4Ba, and CryllBa in these Culex, which may be partly responsible for the toxin synergy characteristic of B. thuringiensis subsp. israelensis de Barjac.

  13. Diversity of Molecular Mechanisms Conferring Carbapenem Resistance to Pseudomonas aeruginosa Isolates from Saudi Arabia

    PubMed Central

    Jeannot, Katy; El-Mahdy, Taghrid S.; Samaha, Hassan A.; Shibl, Atef M.; Plésiat, Patrick; Courvalin, Patrice

    2016-01-01

    Background. This study described various molecular and epidemiological characters determining antibiotic resistance patterns in Pseudomonas aeruginosa isolates. Methods. A total of 34 carbapenem-resistant P. aeruginosa clinical isolates were isolated from samples collected at a tertiary hospital in Riyadh, Saudi Arabia, from January to December 2011. Susceptibility testing, serotyping, molecular characterization of carbapenem resistance, and pulsed-field gel electrophoresis (PFGE) were performed. Results. All isolates were resistant to ceftazidime, and more than half were highly resistant (minimum inhibitory concentration (MIC) > 256 mg/L). Fifteen isolates had MIC values ≥64 mg/L for any of the carbapenems examined. Vietnamese extended-spectrum β-lactamase (VEB-1) (n = 16/34) and oxacillinase (OXA-10) (n = 14/34) were the most prevalent extended-spectrum β-lactamase and penicillinase, respectively. Verona imipenemase (VIM-1, VIM-2, VIM-4, VIM-11, and VIM-28) and imipenemase (IMP-7) variants were found in metallo-β-lactamase producers. A decrease in outer membrane porin gene (oprD) expression was seen in nine isolates, and an increase in efflux pump gene (MexAB) expression was detected in five isolates. Six serotypes (O:1, O:4, O:7, O:10, O:11, and O:15) were found among the 34 isolates. The predominant serotype was O:11 (16 isolates), followed by O:15 (nine isolates). PFGE analysis of the 34 carbapenem-resistant P. aeruginosa isolates revealed 14 different pulsotypes. Conclusions. These results revealed diverse mechanisms conferring carbapenem resistance to P. aeruginosa isolates from Saudi Arabia. PMID:27597874

  14. Apoptosis-related genes confer resistance to Fusarium wilt in transgenic 'Lady Finger' bananas.

    PubMed

    Paul, Jean-Yves; Becker, Douglas K; Dickman, Martin B; Harding, Robert M; Khanna, Harjeet K; Dale, James L

    2011-12-01

    Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense (Foc), is one of the most devastating diseases of banana (Musa spp.). Apart from resistant cultivars, there are no effective control measures for the disease. We investigated whether the transgenic expression of apoptosis-inhibition-related genes in banana could be used to confer disease resistance. Embryogenic cell suspensions of the banana cultivar, 'Lady Finger', were stably transformed with animal genes that negatively regulate apoptosis, namely Bcl-xL, Ced-9 and Bcl-2 3' UTR, and independently transformed plant lines were regenerated for testing. Following a 12-week exposure to Foc race 1 in small-plant glasshouse bioassays, seven transgenic lines (2 × Bcl-xL, 3 × Ced-9 and 2 × Bcl-2 3' UTR) showed significantly less internal and external disease symptoms than the wild-type susceptible 'Lady Finger' banana plants used as positive controls. Of these, one Bcl-2 3' UTR line showed resistance that was equivalent to that of wild-type Cavendish bananas that were included as resistant negative controls. Further, the resistance of this line continued for 23-week postinoculation at which time the experiment was terminated. Using TUNEL assays, Foc race 1 was shown to induce apoptosis-like features in the roots of wild-type 'Lady Finger' plants consistent with a necrotrophic phase in the life cycle of this pathogen. This was further supported by the observed reduction in these effects in the roots of the resistant Bcl-2 3' UTR-transgenic line. This is the first report on the generation of transgenic banana plants with resistance to Fusarium wilt.

  15. The wheat Lr34 multi-pathogen resistance gene confers resistance to anthracnose and rust in sorghum.

    PubMed

    Schnippenkoetter, Wendelin; Lo, Clive; Liu, Guoquan; Dibley, Katherine; Chan, Wai Lung; White, Jodie; Milne, Ricky; Zwart, Alexander; Kwong, Eunjung; Keller, Beat; Godwin, Ian; Krattinger, Simon G; Lagudah, Evans

    2017-03-16

    The ability of the wheat Lr34 multi-pathogen resistance gene (Lr34res) to function across a wide taxonomic boundary was investigated in transgenic Sorghum bicolor. Increased resistance to sorghum rust and anthracnose disease symptoms following infection with the biotrophic pathogen Puccinia purpurea and the hemibiotroph Colletotrichum sublineolum respectively occurred in transgenic plants expressing the Lr34res ABC transporter. Transgenic sorghum lines that highly expressed the wheat Lr34res gene exhibited immunity to sorghum rust compared to the low expressing single copy Lr34res genotype that conferred partial resistance. Pathogen induced pigmentation mediated by flavonoid phytoalexins was evident on transgenic sorghum leaves following P. purpurea infection within 24-72 hours, which paralleled Lr34res gene expression. Elevated expression of flavone synthase II, flavanone 4-reductase and dihydroflavonol reductase genes which control the biosynthesis of flavonoid phytoalexins characterised the highly expressing Lr34res transgenic lines 24 h post inoculation with P. purpurea. Metabolite analysis of mesocotyls infected with C. sublineolum showed increased levels of 3-deoxyanthocyanidin metabolites was associated with Lr34res expression, concomitant with reduced symptoms of anthracnose. This article is protected by copyright. All rights reserved.

  16. Overcoming MITF-conferred drug resistance through dual AURKA/MAPK targeting in human melanoma cells

    PubMed Central

    Pathria, G; Garg, B; Borgdorff, V; Garg, K; Wagner, C; Superti-Furga, G; Wagner, S N

    2016-01-01

    MITF (microphthalmia-associated transcription factor) is a frequently amplified lineage-specific oncogene in human melanoma, whose role in intrinsic drug resistance has not been systematically investigated. Utilizing chemical inhibitors for major signaling pathways/cellular processes, we witness MITF as an elicitor of intrinsic drug resistance. To search kinase(s) targets able to bypass MITF-conferred drug resistance, we employed a multi-kinase inhibitor-directed chemical proteomics-based differential affinity screen in human melanocytes carrying ectopic MITF overexpression. A subsequent methodical interrogation informed mitotic Ser/Thr kinase Aurora Kinase A (AURKA) as a crucial regulator of melanoma cell proliferation and migration, independent of the underlying molecular alterations, including TP53 functional status and MITF levels. Crucially, assessing the efficacy of investigational AURKA inhibitor MLN8237, we pre-emptively witness the procurement of a molecular program consistent with acquired drug resistance. This involved induction of multiple MAPK (mitogen-activated protein kinase) signaling pathway components and their downstream proliferation effectors (Cyclin D1 and c-JUN) and apoptotic regulators (MITF and Bcl-2). A concomitant AURKA/BRAF and AURKA/MEK targeting overcame MAPK signaling activation-associated resistance signature in BRAF- and NRAS-mutated melanomas, respectively, and elicited heightened anti-proliferative activity and apoptotic cell death. These findings reveal a previously unreported MAPK signaling-mediated mechanism of immediate resistance to AURKA inhibitors. These findings could bear significant implications for the application and the success of anti-AURKA approaches that have already entered phase-II clinical trials for human melanoma. PMID:26962685

  17. Antibody response against three widespread bovine viruses is not impaired in Holstein cattle carrying bovine leukocyte antigen DRB3.2 alleles associated with bovine leukemia virus resistance.

    PubMed

    Juliarena, M A; Poli, M; Ceriani, C; Sala, L; Rodríguez, E; Gutierrez, S; Dolcini, G; Odeon, A; Esteban, E N

    2009-01-01

    Due to the wide dissemination of bovine leukemia virus (BLV) infection among dairy cattle, control and eradication programs based on serological detection of infected cattle and subsequent culling face a major economic task. In Argentina, genetic selection of cattle carrying alleles of the bovine leukocyte antigen (BoLA) DRB3.2 gene associated with BLV-infection resistance, like *0902, emerges as the best additional tool toward controlling virus spread. A potential risk in expanding or segregating BoLA selected populations of cattle is that it might increase susceptibility to other common viruses. Special concern raises the strong association found between low proviral load and low antibody titer against major BLV structural proteins. This phenomenon might depend on host genetic factors influencing other viruses requiring, unlike BLV, strong and long-lasting humoral immune response to prevent infection. In this study, we demonstrate that there is no association among neutralizing antibody titers against foot and mouth disease virus, bovine viral diarrhea virus, or bovine herpesvirus type 1 and polymorphism of the BoLA DRB3.2 gene. Conversely, there is strong association between BoLA DRB3.2*0902 and low antibody titers against 2 BLV structural proteins--env gp51 and gag p24--to date, the best BLV resistance marker. There is also significant association between low antibody titers against gp51 and p24 and BoLA DRB3.2*1701 and low antibody titers against p24 and BoLA DRB3.2*1101 or 02. Our data suggest that increasing BoLA-selected BLV-resistant cattle or segregating BoLA-associated alleles to BLV susceptibility would not affect the resistance or the predisposition to bovine viral diarrhea virus, bovine herpesvirus type 1, or foot and mouth disease virus infection.

  18. The Hippo coactivator YAP1 mediates EGFR overexpression and confers chemo-resistance in esophageal cancer

    PubMed Central

    Song, Shumei; Honjo, Soichiro; Jin, Jiankang; Chang, Shih-Shin; Scott, Ailing W; Chen, Qiongrong; Kalhor, Neda; Correa, Arlene M.; Hofstetter, Wayne L.; Albarracin, Constance T.; Wu, Tsung-Teh; Johnson, Randy L.; Hung, Mien-Chie; Ajani, Jaffer A.

    2015-01-01

    Purpose Esophageal cancer (EC) is an aggressive malignancy and often resistant to therapy. Overexpression of EGFR has been associated with poor prognosis of EC patients. However, clinical trials using EGFR inhibitors have not provided benefit for EC patients. Failure of EGFR inhibition may be due to crosstalk with other oncogenic pathways. Experimental Design In this study, expression of YAP1 and EGFR were examined in EAC resistant tumor tissues vs sensitive tissues by immunohistochemistry. Western blot, immunofluorescence, real-time PCR, promoter analysis, site-directed mutagenesis and in vitro and in vivo functional assays were performed to elucidate the YAP1 mediate EGFR expression and transcription and the relationship with chemoresistance in esophageal cancer. Results We demonstrate that Hippo pathway coactivator YAP1 can induce EGFR expression and transcription in multiple cell systems. Both YAP1 and EGFR are overexpressed in resistant EC tissues compared to sensitive EC tissues. Further, we found that YAP1 increases EGFR expression at the level of transcription requiring an intact TEAD binding site in the EGFR promoter. Most importantly, exogenous induction of YAP1 induces resistance to 5-FU and docetaxcel, while knockdown of YAP sensitizes EC cells to these cytotoxics. Verteporfin, a YAP1 inhibitor, effectively inhibits both YAP1 and EGFR expression and sensitizes cells to cytotoxics. Conclusions Our data provide evidence that YAP1 up-regulation of EGFR plays an important role in conferring therapy resistance in EC cells. Targeting YAP1-EGFR axis may be more efficacious than targeting EGFR alone in EC. PMID:25739674

  19. Human ABCB1 confers cells resistance to cytotoxic guanidine alkaloids from Pterogyne nitens.

    PubMed

    Satake, Kazuhiro; Tsukamoto, Megumi; Mitani, Yuji; Regasini, Luis Octavio; da Silva Bolzani, Vanderlan; Efferth, Thomas; Nakagawa, Hiroshi

    2015-01-01

    Multidrug resistance (MDR) caused by human ABCB1 (P-glycoprotein/MDR1) is one of the major obstacles in chemotherapy. To understand the mechanism of MDR by ABCB1 and circumvent the MDR, in the present study, we established human ABCB1-expressing cells (Flp-In-293/ABCB1 cells) and examined the cytotoxic effects of four guanidine alkaloids from Pterogyne nitens (galegine, nitensidine A, pterogynidine and pterogynine) using Flp-In-293/Mock and Flp-In-293/ABCB1 cells. The activity of ABCB1 in Flp-In-293/ABCB1 cells were confirmed by typical substrates for ABCB1 (taxol and vinblastine) in MTT assay. Flp-In-293/ABCB1 cells were also resistant to the four guanidine alkaloids as well as taxol and vinblastine compared to Flp-In-293/Mock cells although the four guanidine alkaloids exhibited cytotoxicity against the two Flp-In-293 cells. Furthermore, the four guanidine alkaloids were also found to stimulate the ATPase activity of ABCB1 in ATPase assays. These results suggest that ABCB1 can confer the resistance to the cytotoxic guanidine alkaloids by transporting them.

  20. Prolactin confers resistance against cisplatin in breast cancer cells by activating glutathione-S-transferase.

    PubMed

    LaPensee, Elizabeth W; Schwemberger, Sandy J; LaPensee, Christopher R; Bahassi, El Mustapha; Afton, Scott E; Ben-Jonathan, Nira

    2009-08-01

    Resistance to chemotherapy is a major obstacle for successful treatment of breast cancer patients. Given that prolactin (PRL) acts as an anti-apoptotic/survival factor in the breast, we postulated that it antagonizes cytotoxicity by chemotherapeutic drugs. Treatment of breast cancer cells with PRL caused variable resistance to taxol, vinblastine, doxorubicin and cisplatin. PRL prevented cisplatin-induced G(2)/M cell cycle arrest and apoptosis. In the presence of PRL, significantly less cisplatin was bound to DNA, as determined by mass spectroscopy, and little DNA damage was seen by gamma-H2AX staining. PRL dramatically increased the activity of glutathione-S-transferase (GST), which sequesters cisplatin in the cytoplasm; this increase was abrogated by Jak and mitogen-activated protein kinase inhibitors. PRL upregulated the expression of the GSTmu, but not the pi, isozyme. A GST inhibitor abrogated antagonism of cisplatin cytotoxicity by PRL. In conclusion, PRL confers resistance against cisplatin by activating a detoxification enzyme, thereby reducing drug entry into the nucleus. These data provide a rational explanation for the ineffectiveness of cisplatin in breast cancer, which is characterized by high expression of both PRL and its receptor. Suppression of PRL production or blockade of its actions should benefit patients undergoing chemotherapy by allowing for lower drug doses and expanded drug options.

  1. Molecular mapping and characterization of two genes conferring resistance to Phytophthora sojae in a soybean landrace PI 567139B

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Phytophthora root and stem rot (PRR), caused by the soil-borne oomycete pathogen Phytophthora sojae, is one of the most destructive diseases of soybean. PRR can be effectively controlled by race-specific genes conferring resistance to P. sojae (Rps). However, the Rps genes are usually non-durable, a...

  2. Detection, introgression and localization of genes conferring specific resistance to Leptosphaeria maculans from Brassica rapa into B. napus.

    PubMed

    Leflon, M; Brun, H; Eber, F; Delourme, R; Lucas, M O; Vallée, P; Ermel, M; Balesdent, M H; Chèvre, A M

    2007-11-01

    Blackleg (stem canker) caused by the fungus Leptosphaeria maculans is one of the most damaging diseases of oilseed rape (Brassica napus). Crop relatives represent a valuable source of "new" resistance genes that could be used to diversify cultivar resistance. B. rapa, one of the progenitors of B. napus, is a potential source of new resistance genes. However, most of the accessions are heterozygous so it is impossible to directly detect the plant genes conferring specific resistance due to the complex patterns of avirulence genes in L. maculans isolates. We developed a strategy to simultaneously characterize and introgress resistance genes from B. rapa, by homologous recombination, into B. napus. One B. rapa plant resistant to one L. maculans isolate was used to produce B. rapa backcross progeny and a resynthesized B. napus plant from which a population of doubled haploid lines was derived after crossing with natural B. napus. We then used molecular analyses and resistance tests on these populations to identify and map the resistance genes and to characterize their introgression from B. rapa into B. napus. Three specific genes conferring resistance to L. maculans (Rlm1, Rlm2 and Rlm7) were identified in B. rapa. Comparisons of genetic maps showed that two of these genes were located on the R7 linkage group, in a region homologous to the region on linkage group N7 in B. napus, where these genes have been reported previously. The results of our study offer new perspectives for gene introgression and cloning in Brassicas.

  3. Mutations in Dalpha1 or Dbeta2 nicotinic acetylcholine receptor subunits can confer resistance to neonicotinoids in Drosophila melanogaster.

    PubMed

    Perry, Trent; Heckel, David G; McKenzie, John A; Batterham, Philip

    2008-05-01

    Resistance to insecticides by modification of their molecular targets is a serious problem in chemical control of many arthropod pests. Neonicotinoids target the nicotinic acetylcholine receptor (nAChR) of arthropods. The spectrum of possible resistance-conferring mutations of this receptor is poorly understood. Prediction of resistance is complicated by the existence of multiple genes encoding the different subunits of this essential component of neurotransmission. We focused on the cluster of three Drosophila melanogaster nAChR subunit genes at cytological region 96A. EMS mutagenesis and selection for resistance to nitenpyram was performed on hybrids carrying a deficiency for this chromosomal region. Two complementation groups were defined for the four strains isolated. Molecular characterisation of the mutations found lesions in two nAChR subunit genes, Dalpha1 (encoding an alpha-type subunit) and Dbeta2 (beta-type). Mutations conferring resistance in beta-type receptors have not previously been reported, but we found several lesions in the Dbeta2 sequence, including locations distant from the predicted neonicotinoid-binding site. This study illustrates that mutations in a single-receptor subunit can confer nitenpyram resistance. Moreover, some of the mutations may protect the insect against nitenpyram by interfering with subunit assembly or channel activation, rather than affecting binding affinities of neonicotinoids to the channel.

  4. Diversity of mechanisms conferring resistance to β-lactams among OXA-23-producing Acinetobacter baumannii clones.

    PubMed

    Cardoso, Juliana Provasi; Cayô, Rodrigo; Girardello, Raquel; Gales, Ana Cristina

    2016-05-01

    A total of 31 unrelated OXA-23-producing Acinetobacter baumannii strains isolated from 14 hospitals located in distinct Brazilian regions were evaluated in this study. These isolates were grouped into 12 different sequence types (STs), of which 7 had unique allelic sequences (ST188, ST189, ST190, ST191, ST192, ST228, and ST299). Most isolates belonged to the clonal complex CC79 followed by CC15 and CC1. Only polymyxin B and minocycline showed good activity against the OXA-23-producing A. baumannii clones. The ISAba1 upstream blaOXA-23, blaOXA-51-like, or ampC was found in 100%, 54.8%, and 77.4% of the isolates, respectively. High resistance rates to ceftazidime and cefotaxime were observed among those isolates possessing ISAba1 upstream ampC, in contrast to those isolates that did not carry this configuration. Moreover, a ≥2 Log2 decrease in the MICs of meropenem and ceftazidime was observed in the presence of phenyl-arginine-β-naphthylamide for 80.6% and 54.8% of isolates, respectively. Overexpression of the adeB was observed in 61.3% of isolates, particularly among those isolates belonging to the ST1 (CC1). It was also verified that ompW was down-regulated in all isolates belonging to the ST15 (CC15). On the other hand, carO and omp33-36 genes were overexpressed in 48.4% and 58.1% of the isolates, respectively. In this study, we show that overexpression of AdeABC system could significantly contribute for resistance to meropenem and ceftazidime among OXA-23-producing A. baumannii clones in Brazil, demonstrating the complexity involved in the β-lactam resistance in such isolates.

  5. Microsomal epoxide hydrolase (EPHX1), slow (exon 3, 113His) and fast (exon 4, 139Arg) alleles confer susceptibility to squamous cell esophageal cancer

    SciTech Connect

    Jain, Meenu; Tilak, Anup Raj; Upadhyay, Rohit; Kumar, Ashwani; Mittal, Balraj

    2008-07-15

    Genetic polymorphisms in xenobiotic metabolizing enzymes may alter risk of various cancers. Present case-control study evaluated the influence of EPHX1 genetic variations on squamous cell esophageal cancer (ESCC) susceptibility in 107 patients and 320 controls. EPHX1 polymorphic alleles were genotyped by direct sequencing (exon 3, Tyr113His) or PCR-RFLP (exon 4, His139Arg). Patients with exon 3 genotypes (Tyr113His, His113His) and 113His allele were at risk of ESCC (OR{sub Tyr113His} 2.0, 95% CI = 1.2-3.4, p = 0.007; OR{sub His113His} 2.3 95% CI = 1.0-5.2, p = 0.03 and OR{sub His} 1.5, 95% CI = 1.0-2.1, p = 0.01). In contrast, individuals with exon 4, 139Arg allele were at low risk of cancer (OR 0.34, 95% CI = 0.20-0.56, p = 0.001). However, none of haplotype combinations of exon 3 (Tyr113His) and exon 4 (His139Arg) polymorphisms showed modulation of risk for ESCC. Sub-grouping of patients based on anatomical location of tumor predicted that patients with exon 3, His113His and Tyr113His genotypes were at higher risk for developing ESCC tumor at upper and middle third locations (OR 4.4, 95% CI = 1.0-18.5, p = 0.04; OR 2.5, 95% CI = 1.3-5.0, p = 0.005 respectively). The frequency of exon 4, His139Arg genotype was significantly lower in ESCC patients with lower third tumor location as compared to controls (14.8% vs. 36.3%, p = 0.02). In case-only study, gene-environment interaction of EPHX1 genotypes with tobacco, alcohol and occupational exposures did not appear to modulate the cancer susceptibility. In conclusion, exon 3, Tyr113His genotype was associated with higher risk of ESCC particularly at upper and middle-third anatomical locations of tumor. However, His139Arg genotype of exon 4, exhibited low risk for ESCC as well as its clinical characteristics.

  6. Low Prevalence of Pfcrt Resistance Alleles among Patients with Uncomplicated Falciparum Malaria in Niger Six Years after Chloroquine Withdrawal

    PubMed Central

    Salissou, Adamou; Zamanka, Halima; Biyghe Binze, Brigitte; Rivière, Taiana; Tichit, Magalie; Ibrahim, Maman Laminou; Fandeur, Thierry

    2014-01-01

    Chloroquine (CQ) resistance is widespread in Africa, but few data are available for Niger. Pfcrt haplotypes (aa 56–118) and ex vivo responses to CQ and amodiaquine were characterized for 26 isolates collected in South Niger from children under 15 years of age suffering from uncomplicated falciparum malaria, six years after the introduction of artemisinin-based combinations and the withdrawal of CQ. The wild-type Pfcrt haplotype CVMNK was found in 22 of the 26 isolates, with CVIET sequences observed in only three of the samples. We also describe for the first time a new CVINT haplotype. The ex vivo responses were better for CVMNK than for CVIET parasites. Pfcrt sequence data were compared with those obtained for 26 additional parasitized blood samples collected in Gabon, from an area of CQ resistance used as a control. Our findings suggest that there has been a significant decline in CQ-resistant genotypes since the previous estimates for Niger were obtained. No such decline in molecular resistance to CQ was observed in the subset of samples collected in similar conditions from Gabon. These results have important implications for public health and support the policy implemented in Niger since 2005, which aims to increase the efficacy and availability of antimalarial drugs whilst controlling the spread of resistance. PMID:25506465

  7. Loss of Cytoplasmic CDK1 Predicts Poor Survival in Human Lung Cancer and Confers Chemotherapeutic Resistance

    PubMed Central

    Zhang, Chunyu; Elkahloun, Abdel G.; Robertson, Matthew; Gills, Joell J.; Tsurutani, Junji; Shih, Joanna H.; Fukuoka, Junya; Hollander, M. Christine; Harris, Curtis C.; Travis, William D.; Jen, Jin; Dennis, Phillip A.

    2011-01-01

    The dismal lethality of lung cancer is due to late stage at diagnosis and inherent therapeutic resistance. The incorporation of targeted therapies has modestly improved clinical outcomes, but the identification of new targets could further improve clinical outcomes by guiding stratification of poor-risk early stage patients and individualizing therapeutic choices. We hypothesized that a sequential, combined microarray approach would be valuable to identify and validate new targets in lung cancer. We profiled gene expression signatures during lung epithelial cell immortalization and transformation, and showed that genes involved in mitosis were progressively enhanced in carcinogenesis. 28 genes were validated by immunoblotting and 4 genes were further evaluated in non-small cell lung cancer tissue microarrays. Although CDK1 was highly expressed in tumor tissues, its loss from the cytoplasm unexpectedly predicted poor survival and conferred resistance to chemotherapy in multiple cell lines, especially microtubule-directed agents. An analysis of expression of CDK1 and CDK1-associated genes in the NCI60 cell line database confirmed the broad association of these genes with chemotherapeutic responsiveness. These results have implications for personalizing lung cancer therapy and highlight the potential of combined approaches for biomarker discovery. PMID:21887332

  8. Resistin confers resistance to doxorubicin-induced apoptosis in human breast cancer cells through autophagy induction

    PubMed Central

    Liu, Zhenyu; Shi, Aiping; Song, Dong; Han, Bing; Zhang, Zhiru; Ma, Le; Liu, Dongxu; Fan, Zhimin

    2017-01-01

    Clear evidence has linked obesity to a high risk of incidence as well as poor clinical outcome of breast cancer. It has been proven that changes in the levels of adipokines caused by obesity are associated with the initiation and progression of breast cancer. Resistin is a novel adipokine that is upregulated in breast cancer patients and promotes breast cancer cell growth, invasion, and migration. The aim of the study was to investigate whether resistin affected the efficacy of doxorubicin (Dox), one of the most effective anthracycline chemotherapeutic agents in the treatment of breast cancer. Treatment with resistin significantly attenuated Dox-induced apoptosis in a dose- and time-dependent manner, resulting in an increase in breast cancer cells survival. Moreover, resistin significantly induced autophagy flux and inhibition of autophagy abrogated the pro-survival effect of resistin in doxorubicin-treated cells. Furthermore, the AMPK/mTOR/ULK1 and JNK signaling pathways were activated by resistin treatment. Inhibition of these two pathways markedly reduced the ratio of LC3B-II/LC3B-I and increased cell apoptosis induced by Dox. For the first time, our findings indicate that resistin confers resistance to doxorubicin-induced apoptosis through autophagy induction and that this process involves the activation of AMPK/mTOR/ULK1 and JNK signaling pathways. Our findings suggest that resistin antagonism may be a novel strategy to overcome resistance to doxorubicin-based chemotherapy in breast cancer patients.

  9. Saccharomyces cerevisiae Elongator mutations confer resistance to the Kluyveromyces lactis zymocin

    PubMed Central

    Frohloff, Frank; Fichtner, Lars; Jablonowski, Daniel; Breunig, Karin D.; Schaffrath, Raffael

    2001-01-01

    Kluyveromyces lactis killer strains secrete a zymocin complex that inhibits proliferation of sensitive yeast genera including Saccharomyces cerevisiae. In search of the putative toxin target (TOT), we used mTn3:: tagging to isolate zymocin-resistant tot mutants from budding yeast. Of these we identified the TOT1, TOT2 and TOT3 genes (isoallelic with ELP1, ELP2 and ELP3, respectively) coding for the histone acetyltransferase (HAT)-associated Elongator complex of RNA polymerase II holoenzyme. Other than the typical elp ts-phenotype, tot phenocopies hypersensitivity towards caffeine and Calcofluor White as well as slow growth and a G1 cell cycle delay. In addition, TOT4 and TOT5 (isoallelic with KTI12 and IKI1, respectively) code for components that associate with Elongator. Intriguingly, strains lacking non-Elongator HATs (gcn5Δ, hat1Δ, hpa3Δ and sas3Δ) or non-Elongator transcription elongation factors TFIIS (dst1Δ) and Spt4p (spt4Δ) cannot confer resistance towards the K.lactis zymocin, thus providing evidence that Elongator equals TOT and that Elongator plays an important role in signalling toxicity of the K.lactis zymocin. PMID:11296232

  10. Specific calcineurin targeting in macrophages confers resistance to inflammation via MKP-1 and p38

    PubMed Central

    Escolano, Amelia; Martínez-Martínez, Sara; Alfranca, Arántzazu; Urso, Katia; Izquierdo, Helena M; Delgado, Mario; Martín, Francisco; Sabio, Guadalupe; Sancho, David; Gómez-del Arco, Pablo; Redondo, Juan Miguel

    2014-01-01

    Macrophages contribute to tissue homeostasis and influence inflammatory responses by modulating their phenotype in response to the local environment. Understanding the molecular mechanisms governing this plasticity would open new avenues for the treatment for inflammatory disorders. We show that deletion of calcineurin (CN) or its inhibition with LxVP peptide in macrophages induces an anti-inflammatory population that confers resistance to arthritis and contact hypersensitivity. Transfer of CN-targeted macrophages or direct injection of LxVP-encoding lentivirus has anti-inflammatory effects in these models. Specific CN targeting in macrophages induces p38 MAPK activity by downregulating MKP-1 expression. However, pharmacological CN inhibition with cyclosporin A (CsA) or FK506 did not reproduce these effects and failed to induce p38 activity. The CN-inhibitory peptide VIVIT also failed to reproduce the effects of LxVP. p38 inhibition prevented the anti-inflammatory phenotype of CN-targeted macrophages, and mice with defective p38-activation were resistant to the anti-inflammatory effect of LxVP. Our results identify a key role for CN and p38 in the modulation of macrophage phenotype and suggest an alternative treatment for inflammation based on redirecting macrophages toward an anti-inflammatory status. PMID:24596247

  11. Characterization of a Variant of vga(A) Conferring Resistance to Streptogramin A and Related Compounds

    PubMed Central

    Haroche, Julien; Allignet, Jeanine; Buchrieser, Carmen; El Solh, Névine

    2000-01-01

    A variant of the vga(A) gene (1,575 bp), encoding an ATP-binding cassette protein conferring resistance to streptogramin A and related antibiotics, was cloned from the chromosome of a Staphylococcus aureus clinical isolate and sequenced. The sequence of the variant was similar to that of the vga(A) gene (83.2% identity). However, the G+C content of the variant (35.6%) was higher than that of vga(A) (29%) and there was no cross hybridization between vga(A) and the variant at high stringency (≥60°C), the highest temperature at which a signal was detected being 55°C. Unlike previous reports for vga(A) and vga(B), the variant of vga(A) may be present in multiple copies in the genome. These copies are chromosomal in some isolates and both chromosomal and plasmid-borne in others. Nucleotide sequences hybridizing at 65°C with the vga(A) variant were found in all the staphylococcal strains harboring plasmids carrying both vga(B) and vat(B), which also encode resistance to streptogramin A. PMID:10952567

  12. Disruptive environmental chemicals and cellular mechanisms that confer resistance to cell death

    PubMed Central

    Narayanan, Kannan Badri; Ali, Manaf; Barclay, Barry J.; Cheng, Qiang (Shawn); D’Abronzo, Leandro; Dornetshuber-Fleiss, Rita; Ghosh, Paramita M.; Gonzalez Guzman, Michael J.; Lee, Tae-Jin; Leung, Po Sing; Li, Lin; Luanpitpong, Suidjit; Ratovitski, Edward; Rojanasakul, Yon; Romano, Maria Fiammetta; Romano, Simona; Sinha, Ranjeet K.; Yedjou, Clement; Al-Mulla, Fahd; Al-Temaimi, Rabeah; Amedei, Amedeo; Brown, Dustin G.; Ryan, Elizabeth P.; Colacci, Anna Maria; Hamid, Roslida A.; Mondello, Chiara; Raju, Jayadev; Salem, Hosni K.; Woodrick, Jordan; Scovassi, A.Ivana; Singh, Neetu; Vaccari, Monica; Roy, Rabindra; Forte, Stefano; Memeo, Lorenzo; Kim, Seo Yun; Bisson, William H.; Lowe, Leroy; Park, Hyun Ho

    2015-01-01

    Cell death is a process of dying within biological cells that are ceasing to function. This process is essential in regulating organism development, tissue homeostasis, and to eliminate cells in the body that are irreparably damaged. In general, dysfunction in normal cellular death is tightly linked to cancer progression. Specifically, the up-regulation of pro-survival factors, including oncogenic factors and antiapoptotic signaling pathways, and the down-regulation of pro-apoptotic factors, including tumor suppressive factors, confers resistance to cell death in tumor cells, which supports the emergence of a fully immortalized cellular phenotype. This review considers the potential relevance of ubiquitous environmental chemical exposures that have been shown to disrupt key pathways and mechanisms associated with this sort of dysfunction. Specifically, bisphenol A, chlorothalonil, dibutyl phthalate, dichlorvos, lindane, linuron, methoxychlor and oxyfluorfen are discussed as prototypical chemical disruptors; as their effects relate to resistance to cell death, as constituents within environmental mixtures and as potential contributors to environmental carcinogenesis. PMID:26106145

  13. HPV-18 confers resistance to TNF-{alpha} in organotypic cultures of human keratinocytes

    SciTech Connect

    Boccardo, Enrique . E-mail: eboccardo@ludwig.org.br; Noya, Francisco; Broker, Thomas R.; Chow, Louise T.; Villa, Luisa L.

    2004-10-25

    The proinflammatory cytokine tumor necrosis factor-alpha (TNF-{alpha}) inhibits normal keratinocytes proliferation. However, many human papillomavirus (HPV)-immortalized or transformed cell lines are resistant to TNF-{alpha} antiproliferative effect. The present study analyzes the effects of TNF-{alpha} on organotypic cultures of primary human keratinocytes (PHKs) that express HPV-18 oncogenes. Raft cultures prepared with PHKs acutely transfected with HPV-18 whole genome or infected with recombinant retroviruses containing only E6/E7 or E7 were treated with 2 nM TNF-{alpha}. While BrdU incorporation into basal/parabasal cells of normal PHKs cultures was markedly inhibited by TNF-{alpha} cultures transfected with HPV-18 whole genome showed proliferation in all cell strata. Furthermore, BrdU incorporation into cultures expressing E6/E7 or E7 was not significantly reduced, indicating that E7 alone confers partial resistance to TNF-{alpha}. Besides, TNF-{alpha} treatment did not alter p16{sup ink4a}, p21{sup cip1}, p27{sup kip1}, or cyclin E levels, but did reduce cyclin A and PCNA levels in sensitive cells.

  14. Lung-specific loss of the laminin α3 subunit confers resistance to mechanical injury.

    PubMed

    Urich, Daniela; Eisenberg, Jessica L; Hamill, Kevin J; Takawira, Desire; Chiarella, Sergio E; Soberanes, Saul; Gonzalez, Angel; Koentgen, Frank; Manghi, Tomas; Hopkinson, Susan B; Misharin, Alexander V; Perlman, Harris; Mutlu, Gokhan M; Budinger, G R Scott; Jones, Jonathan C R

    2011-09-01

    Laminins are heterotrimeric glycoproteins of the extracellular matrix that are secreted by epithelial cells and which are crucial for the normal structure and function of the basement membrane. We have generated a mouse harboring a conditional knockout of α3 laminin (Lama3(fl/fl)), one of the main laminin subunits in the lung basement membrane. At 60 days after intratracheal treatment of adult Lama3(fl/fl) mice with an adenovirus encoding Cre recombinase (Ad-Cre), the protein abundance of α3 laminin in whole lung homogenates was more than 50% lower than that in control-treated mice, suggesting a relatively long half-life for the protein in the lung. Upon exposure to an injurious ventilation strategy (tidal volume of 35 ml per kg of body weight for 2 hours), the mice with a knockdown of the α3 laminin subunit had less severe injury, as shown by lung mechanics, histology, alveolar capillary permeability and survival when compared with Ad-Null-treated mice. Knockdown of the α3 laminin subunit resulted in evidence of lung inflammation. However, this did not account for their resistance to mechanical ventilation. Rather, the loss of α3 laminin was associated with a significant increase in the collagen content of the lungs. We conclude that the loss of α3 laminin in the alveolar epithelium results in an increase in lung collagen, which confers resistance to mechanical injury.

  15. Heritable variation in the foliar secondary metabolite sideroxylonal in Eucalyptus confers cross-resistance to herbivores.

    PubMed

    Andrew, Rose L; Wallis, Ian R; Harwood, Chris E; Henson, Michael; Foley, William J

    2007-10-01

    Plants encounter a broad range of natural enemies and defend themselves in diverse ways. The cost of defense can be reduced if a plant secondary metabolite confers resistance to multiple herbivores. However, there are few examples of positively correlated defenses in plants against herbivores of different types. We present evidence that a genetically variable chemical trait that acts as a strong antifeedant to mammalian herbivores of Eucalyptus also deters insect herbivores, suggesting a possible mechanism for cross-resistance. We provide field confirmation that sideroxylonal, an important antifeedant for mammalian herbivores, also determines patterns of damage by Christmas beetles, a specialist insect herbivore of Eucalyptus. In a genetic progeny trial of Eucalyptus tricarpa, we found significant heritabilities of sideroxylonal concentration (0.60), overall insect damage (0.34), and growth traits (0.30-0.53). Population of origin also had a strong effect on each trait. Negative phenotypic correlations were observed between sideroxylonal and damage, and between damage and growth. No relationship was observed between sideroxylonal concentration and any growth trait. Our results suggest that potential for evolution by natural selection of sideroxylonal concentrations is not strongly constrained by growth costs and that both growth and defense traits can be successfully incorporated into breeding programs for plantation trees.

  16. Activation of the Met kinase confers acquired drug resistance in FGFR-targeted lung cancer therapy.

    PubMed

    Kim, S-M; Kim, H; Yun, M R; Kang, H N; Pyo, K-H; Park, H J; Lee, J M; Choi, H M; Ellinghaus, P; Ocker, M; Paik, S; Kim, H R; Cho, B C

    2016-07-18

    Aberrant fibroblast growth factor receptor (FGFR) activation/expression is a common feature in lung cancer (LC). In this study, we evaluated the antitumor activity of and the mechanisms underlying acquired resistance to two potent selective FGFR inhibitors, AZD4547 and BAY116387, in LC cell lines. The antitumor activity of AZD4547 and BAY1163877 was screened in 24 LC cell lines, including 5 with FGFR1 amplification. Two cell lines containing FGFR1 amplifications, H1581 and DMS114, were sensitive to FGFR inhibitors (IC50<250 nm). Clones of FGFR1-amplified H1581 cells resistant to AZD4547 or BAY116387 (H1581AR and H1581BR cells, respectively) were established. Receptor tyrosine kinase (RTK) array and immunoblotting analyses showed strong overexpression and activation of Met in H1581AR/BR cells, compared with that in the parental cells. Gene set enrichment analysis against the Kyoto Encyclopedia of Genes and Genomes (KEGG) database showed that cytokine-cytokine receptor interaction pathways were significantly enriched in H1581AR/BR cells, with Met contributing significantly to the core enrichment. Genomic DNA quantitative PCR and fluorescent in situ hybridization analyses showed MET amplification in H1581AR, but not in H1581BR, cells. Met amplification drives acquired resistance to AZD4547 in H1581AR cells by activating ErbB3. Combination treatment with FGFR inhibitors and an anaplastic lymphoma kinase (ALK)/Met inhibitor, crizotinib, or Met-specific short interfering RNA (siRNA) synergistically inhibited cell proliferation in both H1581AR and H1581BR cells. Conversely, ectopic expression of Met in H1581 cells conferred resistance to AZD4547 and BAY1163877. Acquired resistance to FGFR inhibitors not only altered cellular morphology, but also promoted migration and invasion of resistant clones, in part by inducing epithelial-to-mesenchymal transition. Taken together, our data suggest that Met activation is sufficient to bypass dependency on FGFR signaling. Concurrent

  17. Two Non-target Recessive Genes Confer Resistance to the Anti-Oomycete Microtubule Inhibitor Zoxamide in Phytophthora capsici

    PubMed Central

    Cai, Meng; Zhu, Shusheng; Pang, Zhili; Liu, Xili

    2014-01-01

    This study characterized isolates of P. capsici that had developed a novel mechanism of resistance to zoxamide, which altered the minimum inhibition concentration (MIC) but not the EC50. Molecular analysis revealed that the β-tubulin gene of the resistant isolates contained no mutations and was expressed at the same level as in zoxamide-sensitive isolates. This suggested that P. capsici had developed a novel non-target-site-based resistance to zoxamide. Analysis of the segregation ratio of zoxamide-resistance in the sexual progeny of the sensitive isolates PCAS1 and PCAS2 indicated that the resistance to zoxamide was controlled by one or more recessive nuclear genes. Furthermore, the segregation of resistance in the F1, F2, and BC1 progeny was in accordance with the theoretical ratios of the χ2 test (P>0.05), which suggested that the resistance to zoxamide was controlled by two recessive genes, and that resistance to zoxamide occurred when at least one pair of these alleles was homozygous. This implies that the risk of zoxamide-resistance in P. capsici is low to moderate. Nevertheless this potential for resistance should be monitored closely, especially if two compatible mating types co-exist in the same field. PMID:24586697

  18. Two non-target recessive genes confer resistance to the anti-oomycete microtubule inhibitor zoxamide in Phytophthora capsici.

    PubMed

    Bi, Yang; Chen, Lei; Cai, Meng; Zhu, Shusheng; Pang, Zhili; Liu, Xili

    2014-01-01

    This study characterized isolates of P. capsici that had developed a novel mechanism of resistance to zoxamide, which altered the minimum inhibition concentration (MIC) but not the EC50. Molecular analysis revealed that the β-tubulin gene of the resistant isolates contained no mutations and was expressed at the same level as in zoxamide-sensitive isolates. This suggested that P. capsici had developed a novel non-target-site-based resistance to zoxamide. Analysis of the segregation ratio of zoxamide-resistance in the sexual progeny of the sensitive isolates PCAS1 and PCAS2 indicated that the resistance to zoxamide was controlled by one or more recessive nuclear genes. Furthermore, the segregation of resistance in the F1, F2, and BC1 progeny was in accordance with the theoretical ratios of the χ(2) test (P>0.05), which suggested that the resistance to zoxamide was controlled by two recessive genes, and that resistance to zoxamide occurred when at least one pair of these alleles was homozygous. This implies that the risk of zoxamide-resistance in P. capsici is low to moderate. Nevertheless this potential for resistance should be monitored closely, especially if two compatible mating types co-exist in the same field.

  19. Class 1 integrons in non-clonal multidrug-resistant Acinetobacter baumannii from Iran, description of the new blaIMP-55 allele in In1243.

    PubMed

    Azizi, Omid; Shakibaie, Mohammad Reza; Badmasti, Farzad; Modarresi, Farzan; Ramazanzadeh, Rashid; Mansouri, Shahla; Shahcheraghi, Fereshteh

    2016-09-01

    Infections and outbreaks caused by multidrug-resistant Acinetobacter baumannii (MDR-AB) are prevalent and have been reported worldwide over the past 20 or more years. Class 1 integron in MDR-AB plays an important role in the spread of antibiotic resistance in clinical settings. This study has been conducted to evaluate the detection of metallo-β-lactamase, characterization of class 1 integron and determination of clonal relatedness among A. baumannii hospital isolates. Sixty-five clinical isolates of MDR-AB were recovered from two Iranian hospital's intensive care units from February to August 2013. Integrase (intI1) and blaIMP genes were detected in 70.8 % (n=46/65) and 9.23 % (n=6/65) of the isolates using PCR assay, respectively. No other metallo-β-lactamase genes (blaVIM, blaSIM and blaNDM) were detected. PCR sequencing of integron gene cassette revealed the following arrays: blaOXA10-aacA4-blaIMP-55-cmlA5 (as a novel array was designated In1243), aacC1 and aadA1. Analysis of blaIMP gene revealed a new allele designated as blaIMP-55. Gene transfer experiment by conjugation showed the 36 kb conjugative plasmid harbouring In1243. The clonal assessment by repetitive extragenic palindromic PCR demonstrated a high-degree relatedness among the strains, but strains harbouring In1243 displayed a different repetitive extragenic palindromic PCR profile. In this study, we found that a novel class 1 integron (In1243) that encoded a new blaIMP allele resided on a transferable plasmid in non-clonal strains of MDR-AB.

  20. Lr41, Lr39, and a leaf rust resistance gene from Aegilops cylindrica may be allelic and are located on wheat chromosome 2DS.

    PubMed

    Singh, Sukhwinder; Franks, C D; Huang, L; Brown-Guedira, G L; Marshall, D S; Gill, B S; Fritz, A

    2004-02-01

    The leaf rust resistance gene Lr41 in wheat germplasm KS90WGRC10 and a resistance gene in wheat breeding line WX93D246-R-1 were transferred to Triticum aestivum from Aegilops tauschii and Ae. cylindrica, respectively. The leaf rust resistance gene in WX93D246-R-1 was located on wheat chromosome 2D by monosomic analysis. Molecular marker analysis of F(2) plants from non-critical crosses determined that this gene is 11.2 cM distal to marker Xgwm210 on the short arm of 2D. No susceptible plants were detected in a population of 300 F(2) plants from a cross between WX93D246-R-1 and TA 4186 ( Lr39), suggesting that the gene in WX93D246-R-1 is the same as, or closely linked to, Lr39. In addition, no susceptible plants were detected in a population of 180 F(2) plants from the cross between KS90WGRC10 and WX93D246-R-1. The resistance gene in KS90WGRC10, Lr41, was previously reported to be located on wheat chromosome 1D. In this study, no genetic association was found between Lr41 and 51 markers located on chromosome 1D. A population of 110 F(3 )lines from a cross between KS90WGRC10 and TAM 107 was evaluated with polymorphic SSR markers from chromosome 2D and marker Xgdm35 was found to be 1.9 cM proximal to Lr41. When evaluated with diverse isolates of Puccinia triticina, similar reactions were observed on WX93D246-R-1, KS90WGRC10, and TA 4186. The results of mapping, allelism, and race specificity test indicate that these germplasms likely have the same gene for resistance to leaf rust.

  1. Sequence variation at the rice blast resistance gene Pi-km locus: Implications for the development of allele specific markers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The recently cloned blast resistance (R) gene Pi-km protects rice crops against specific races of the fungal pathogen Magnaporthe oryzae in a gene-for-gene manner. The use of blast R genes remains the most cost-effective method for an integrated disease management strategy. To facilitate rice breed...

  2. Allele, genotype, and haplotype data for BSE-resistance polymorphisms from healthy U.S. holstein cattle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bovine spongiform encephalopathy (BSE) is a neurodegenerative disease of cattle caused by abnormally folded prion proteins. Two regulatory region polymorphisms in the bovine prion gene are associated with resistance to classical BSE disease: a 23 bp region in the promoter that contains a binding si...

  3. Overexpression of a soybean salicylic acid methyltransferase gene confers resistance to soybean cyst nematode.

    PubMed

    Lin, Jingyu; Mazarei, Mitra; Zhao, Nan; Zhu, Junwei J; Zhuang, Xiaofeng; Liu, Wusheng; Pantalone, Vincent R; Arelli, Prakash R; Stewart, Charles N; Chen, Feng

    2013-12-01

    Salicylic acid plays a critical role in activating plant defence responses after pathogen attack. Salicylic acid methyltransferase (SAMT) modulates the level of salicylic acid by converting salicylic acid to methyl salicylate. Here, we report that a SAMT gene from soybean (GmSAMT1) plays a role in soybean defence against soybean cyst nematode (Heterodera glycines Ichinohe, SCN). GmSAMT1 was identified as a candidate SCN defence-related gene in our previous analysis of soybean defence against SCN using GeneChip microarray experiments. The current study started with the isolation of the full-length cDNAs of GmSAMT1 from a SCN-resistant soybean line and from a SCN-susceptible soybean line. The two cDNAs encode proteins of identical sequences. The GmSAMT1 cDNA was expressed in Escherichia coli. Using in vitro enzyme assays, E. coli-expressed GmSAMT1 was confirmed to function as salicylic acid methyltransferase. The apparent Km value of GmSAMT1 for salicylic acid was approximately 46 μM. To determine the role of GmSAMT1 in soybean defence against SCN, transgenic hairy roots overexpressing GmSAMT1 were produced and tested for SCN resistance. Overexpression of GmSAMT1 in SCN-susceptible backgrounds significantly reduced the development of SCN, indicating that overexpression of GmSAMT1 in the transgenic hairy root system could confer resistance to SCN. Overexpression of GmSAMT1 in transgenic hairy roots was also found to affect the expression of selected genes involved in salicylic acid biosynthesis and salicylic acid signal transduction.

  4. GSL2 over-expression confers resistance to Pectobacterium atrosepticum in potato.

    PubMed

    Mohan, Sara; Meiyalaghan, Sathiyamoorthy; Latimer, Julie M; Gatehouse, Michelle L; Monaghan, Katrina S; Vanga, Bhanupratap R; Pitman, Andrew R; Jones, E Eirian; Conner, Anthony J; Jacobs, Jeanne M E

    2014-03-01

    Over-expression of the potato Gibberellin Stimulated-Like 2 ( GSL2 ) gene in transgenic potato confers resistance to blackleg disease incited by Pectobacterium atrosepticum and confirms a role for GSL2 in plant defence. The Gibberellin Stimulated-Like 2 (GSL2) gene (also known as Snakin 2) encodes a cysteine-rich, low-molecular weight antimicrobial peptide produced in potato plants. This protein is thought to play important roles in the innate defence against invading microbes. Over-expression of the GSL2 gene in potato (cultivar Iwa) was achieved using Agrobacterium-mediated gene transfer of a plant expression vector with the potato GSL2 gene under the regulatory control elements of the potato light-inducible Lhca3 gene. The resulting plants were confirmed as being transgenic by PCR, and subsequently analysed for transcriptional expression of the Lhca3-GSL2-Lhca3 chimeric potato gene. Quantitative RT-PCR analysis demonstrated that the majority of the transgenic potato lines over-expressed the GSL2 gene at the mRNA level. Based on qRT-PCR results and evaluation of phenotypic appearance, eight lines were selected for further characterisation and evaluated in bioassays for resistance to Pectobacterium atrosepticum (formerly Erwinia carotovora subsp. atroseptica), the causal agent of blackleg in potato. Three independent pathogenicity bioassays showed that transgenic lines with significantly increased transcriptional expression of the GSL2 gene exhibit resistance to blackleg disease. This establishes a functional role for GSL2 in plant defence against pathogens in potato.

  5. Stable integration and expression of a plant defensin in tomato confers resistance to fusarium wilt.

    PubMed

    Abdallah, Naglaa A; Shah, Dilip; Abbas, Dina; Madkour, Magdy

    2010-01-01

    Plant defensins are small cysteine-rich peptides which belong to a group of pathogenasis related defense mechanism proteins. The proteins inhibit the growth of a broad range of microbes and are highly stable under extreme environmental stresses. Tomato cultivation is affected by fungal disease such as Fusarium wilt. In order to overcome fungal damages, transgenic tomato plants expressing the Medicago sativa defensin gene MsDef1 under the control of the CaMV 35S promoter were developed. The Fusarium-susceptible tomato (Lycobersicum esculentum Mill) cultivar CastleRock was used for transformation to acquire fungal resistance. Hypocotyl with a part of cotyledon (hypocotyledonary) for young tomato seedlings were used as an explant material and transformation was performed using the biolistic delivery system. Bombarded shoots were selected on regeneration medium supplemented with hygromycin and suitable concentrations of BA, zeatin ripozide and AgNO(3). Putative transgenic plantlets of T(0) were confirmed by PCR analysis using primers specific for the transgene and the transformation frequency obtained was 52.3%. Transformation and transcription of transgenes were confirmed in T(1) by PCR, Southern hybridizations, and reverse-transcription PCR (RT-PCR). The copy numbers of integrated transgene into tomato genome ranged between 1-3 copies. Greenhouse bioassay was performed on the transgenic T(1) and T(2) young seedlings and non-transgenic controls by challenging with a vigorous isolate of the fungal pathogen Fusarium oxysporum f. sp. Lycopersici. The level of fungal infectivity was determined using RT-PCR with tomatinase specific primers. Transgenic lines were more resistant to infection by fusarium than the control plants. These results indicated that overexpressing defensins in transgenic plants confer resistance to fungal pathogens.

  6. RNA-Seq analysis of a soybean near-isogenic line carrying bacterial leaf pustule-resistant and -susceptible alleles.

    PubMed

    Kim, Kil Hyun; Kang, Yang Jae; Kim, Dong Hyun; Yoon, Min Young; Moon, Jung-Kyung; Kim, Moon Young; Van, Kyujung; Lee, Suk-Ha

    2011-12-01

    Bacterial leaf pustule (BLP) disease is caused by Xanthomonas axonopodis pv. glycines (Xag). To investigate the plant basal defence mechanisms induced in response to Xag, differential gene expression in near-isogenic lines (NILs) of BLP-susceptible and BLP-resistant soybean was analysed by RNA-Seq. Of a total of 46 367 genes that were mapped to soybean genome reference sequences, 1978 and 783 genes were found to be up- and down-regulated, respectively, in the BLP-resistant NIL relative to the BLP-susceptible NIL at 0, 6, and 12h after inoculation (hai). Clustering analysis revealed that these genes could be grouped into 10 clusters with different expression patterns. Functional annotation based on gene ontology (GO) categories was carried out. Among the putative soybean defence response genes identified (GO:0006952), 134 exhibited significant differences in expression between the BLP-resistant and -susceptible NILs. In particular, pathogen-associated molecular pattern (PAMP) and damage-associated molecular pattern (DAMP) receptors and the genes induced by these receptors were highly expressed at 0 hai in the BLP-resistant NIL. Additionally, pathogenesis-related (PR)-1 and -14 were highly expressed at 0 hai, and PR-3, -6, and -12 were highly expressed at 12 hai. There were also significant differences in the expression of the core JA-signalling components MYC2 and JASMONATE ZIM-motif. These results indicate that powerful basal defence mechanisms involved in the recognition of PAMPs or DAMPs and a high level of accumulation of defence-related gene products may contribute to BLP resistance in soybean.

  7. Lily ASR protein-conferred cold and freezing resistance in Arabidopsis.

    PubMed

    Hsu, Yi-Feng; Yu, Shu-Chuan; Yang, Chin-Ying; Wang, Co-Shine

    2011-09-01

    The lily LLA23 protein is a member of the abscisic acid, stress and ripening-induced (ASR) protein family. Constitutive overexpression of LLA23 under the cauliflower mosaic virus 35S promoter confers cold and freezing tolerance in Arabidopsis. The phenotypical growth and survival percentage of the two transgenic 35S::LLA23 plants showed higher resistance to cold and freezing conditions than those of wild-type (WT) plants. The electrolyte leakage in WT leaves increased by approximately fourfold at -2 °C relative to that at 22 °C whereas both transgenic leaves showed little ion leakage under the same conditions. A microarray analysis of LLA23-overexpressing transgenic line, 35S::LLA23E, under normal growing conditions was previously conducted by Yang et al. (Protoplasma, 2008, 233:241-254). Microarray analysis showed that 12 cold-responsive genes are upregulated and 25 cold-responsive genes are downregulated by lily ASR. Many ASR-regulated genes encode proteins involved in the classes of defense/stress-related, transcription, and metabolism. Quantitative polymerase chain reaction analysis confirms the changes in mRNA levels observed in the microarray analysis. Thus, our results provide in vivo evidence implying that LLA23 mediates cold/freezing stress-responsive signaling. To gain further insight into the functions of LLA23 protein, an in vitro enzyme protection assay was used in which lactate dehydrogenase and malate dehydrogenase were subjected to unfavorable conditions. The assay revealed that both enzyme activities were significantly retained with the addition of LLA23, which was superior to either trehalose or BSA, suggesting that the LLA23 protein can protect enzymatic activities against freeze-thaw cycles. The 35S::LLA23 seedlings also exhibited enzyme activity superior to WT at -4 °C. These results suggest that LLA23 may act as an osmoprotectant as well as a transcription factor to confer 35S::LLA23 plants enhanced cold and freezing resistance.

  8. A novel measurement of allele discrimination for assessment of allele-specific silencing by RNA interference.

    PubMed

    Takahashi, Masaki; Hohjoh, Hirohiko

    2014-11-01

    Allele-specific silencing by RNA interference (ASP-RNAi) is an atypical RNAi that is capable of discriminating target alleles from non-target alleles, and may be therapeutically useful for specific inhibition of disease-causing alleles without affecting their corresponding normal alleles. However, it is difficult to design and select small interfering RNA (siRNAs) that confer ASP-RNAi. A major problem is that there are few appropriate measures in determining optimal allele-specific siRNAs. Here we show two novel formulas for calculating a new measure of allele-discrimination, named "ASP-score". The formulas and ASP-score allow for an unbiased determination of optimal siRNAs, and may contribute to characterizing such allele-specific siRNAs.

  9. ALK F1174V mutation confers sensitivity while ALK I1171 mutation confers resistance to alectinib. The importance of serial biopsy post progression.

    PubMed

    Ou, Sai-Hong; Milliken, Jeffrey C; Azada, Michele C; Miller, Vincent A; Ali, Siraj M; Klempner, Samuel J

    2016-01-01

    Many acquired resistant mutations to the anaplastic lymphoma kinase (ALK) gene have been identified during treatment of ALK-rearranged non-small cell lung cancer (NSCLC) patients with crizotinib, ceritinib, and alectinib. These various acquired resistant ALK mutations confer differential sensitivities to various ALK inhibitors and may provide guidance on how to sequence the use of many of the second generation ALK inhibitors. We described a patient who developed an acquired ALK F1174V resistant mutation on progression from crizotinib that responded to alectinib for 18 months but then developed an acquired ALK I1171S mutation to alectinib. Both tumor samples had essentially the same genomic profile by comprehensive genomic profiling otherwise. This is the first patient report that demonstrates ALK F1174V mutation is sensitive to alectinib and further confirms missense acquired ALK I1171 mutation is resistant to alectinib. Sequential tumor re-biopsy for comprehensive genomic profiling (CGP) is important to appreciate the selective pressure during treatment with various ALK inhibitors underpinning the evolution of the disease course of ALK+NSCLC patients while on treatment with the various ALK inhibitors. This approach will likely help inform the optimal sequencing strategy as more ALK inhibitors become available. This case report also validates the importance of developing structurally distinct ALK inhibitors for clinical use to overcome non-cross resistant ALK mutations.

  10. Cbf genes of the Fr-A2 allele are differentially regulated between long-term cold acclimated crown tissue of freeze-resistant and – susceptible, winter wheat mutant lines

    PubMed Central

    Sutton, Fedora; Chen, Ding-Geng; Ge, Xijin; Kenefick, Don

    2009-01-01

    Background In order to identify genes that might confer and maintain freeze resistance of winter wheat, a comparative transcriptome analysis was performed between control and 4 wk cold-acclimated crown tissue of two winter wheat lines that differ in field freeze survival. The lines, generated by azide mutagenesis of the winter wheat cultivar 'Winoka' were designated FR (75% survival) and FS (30% survival). Using two winter lines for this comparative analysis removed the influence of differential expression of the vernalization genes and allowed our study to focus on Cbf genes located within the Fr-A2 allele independent of the effect of the closely mapped Vrn allele. Results Vernalization genes, (Vrn-A1, B1 and D1), and the transcription factor gene, TaVrt-2, were up-regulated to the same extent in FR and FS lines with cold acclimation thus confirming that azide mutagenesis had not modified the winter habitat of the lines. One category of Cbf genes, (Cbf-2, -A22 and B-22) reflected an increase in level of expression with cold acclimation in both FR and FS lines. Another category of Cbf genes (Cbf-3, -5, -6, -12, -14 and -19) were differentially expressed between cold-acclimated FR and FS lines relative to the non-acclimated controls. Comparison of expression patterns of the two categories of Cbf genes with the expression patterns of a set of ABA-dependent and -independent Cor/Lea genes revealed similar patterns of expression for this sample of Cor/Lea genes with that for Cbf-2 and -22. This pattern of expression was also exhibited by the Vrn genes. Conclusion Some Cor/Lea genes may be co-regulated by the Vrn genes during cold acclimation and the Vrn genes may also control the expression of Cbf-2, -A22 and -B22. The increased freeze survival by the FR line and the increase in expression levels of wheat Cbf genes, Cbf-3, -5, -6, -12, -14 and -19 with cold acclimation in the FR line suggests a possible gain of function mutation resulting in higher levels of expression

  11. Evidence for a Central Role for PfCRT in Conferring Plasmodium falciparum Resistance to Diverse Antimalarial Agents

    PubMed Central

    Johnson, David J.; Fidock, David A.; Mungthin, Mathirut; Lakshmanan, Viswanathan; Sidhu, Amar Bir Singh; Bray, Patrick G.; Ward, Stephen A.

    2010-01-01

    Summary Chloroquine resistance in Plasmodium falciparum is primarily conferred by mutations in pfcrt. Parasites resistant to chloroquine can display hypersensitivity to other antimalarials; however, the patterns of cross-resistance are complex, and the genetic basis has remained elusive. We show that stepwise selection for resistance to amantadine or halofantrine produced previously unknown pfcrt mutations (including S163R), which were associated with a loss of verapamil-reversible chloroquine resistance. This was accompanied by restoration of efficient chloroquine binding to hematin in these selected lines. This S163R mutation provides insight into a mechanism by which PfCRT could gate the transport of protonated chloroquine through the digestive vacuole membrane. Evidence for the presence of this mutation in a Southeast Asian isolate supports the argument for a broad role for PfCRT in determining levels of susceptibility to structurally diverse antimalarials. PMID:15383277

  12. A new point mutation in the iron-sulfur subunit of succinate dehydrogenase confers resistance to boscalid in Sclerotinia sclerotiorum.

    PubMed

    Wang, Yong; Duan, Yabing; Wang, Jianxin; Zhou, Mingguo

    2015-09-01

    Research has established that mutations in highly conserved amino acids of the succinate dehydrogenase (SDH) complex in various fungi confer SDH inhibitor (SDHI) resistance. For Sclerotinia sclerotiorum (Lib.) de Bary, a necrotrophic fungus with a broad host range and a worldwide distribution, boscalid resistance has been attributed to the mutation H132R in the highly conserved SdhD subunit protein of the SDH complex. In our previous study, however, only one point mutation, A11V in SdhB (GCA to GTA change in SdhB), was detected in S. sclerotiorum boscalid-resistant (BR) mutants. In the current study, replacement of the SdhB gene in a boscalid-sensitive (BS) S. sclerotiorum strain with the mutant SdhB gene conferred resistance. Compared with wild-type strains, BR and GSM (SdhB gene in the wild-type strain replaced by the mutant SdhB gene) mutants were more sensitive to osmotic stress, lacked the ability to produce sclerotia and exhibited lower expression of the pac1 gene. Importantly, the point mutation was not located in the highly conserved sequence of the iron-sulfur subunit of SDH. These results suggest that resistance based on non-conserved vs. conserved protein domains differs in mechanism. In addition to increasing our understanding of boscalid resistance in S. sclerotiorum, the new information will be useful for the development of alternative antifungal drugs.

  13. Concentrated polymer brush-modified silica particle coating confers biofouling-resistance on modified materials.

    PubMed

    Yoshikawa, Chiaki; Qiu, Jun; Shimizu, Yoshihisa; Huang, Chih-Feng; Gelling, Onko-Jan; van den Bosch, Edith

    2017-01-01

    Biofouling, an undesired adsorption of biological material to otherwise inert surfaces, is detrimental in medical, pharmaceutical, and other sectors. Concentrated polymer brushes (CPB) confer non-biofouling properties on modified surfaces but are cumbersome to fabricate. Here, a simple and versatile method of fabricating non-biofouling coatings for various substrates was developed using CPB-modified silica nanoparticles (SiPs). Concentrated poly(poly(ethylene glycol) methyl ether methacrylate) (PPEGMA) brushes were grafted on SiPs by surface-initiated atom transfer radical polymerization. CPB-SiPs were spin-coated onto silicon wafers or quartz crystal microbalance (QCM) sensor chips with phenyl azido cross-linkers. SiP cross-linking was then performed by ultra violet irradiation for 20s, or by heating at 120°C for 12h. Protein adsorption to coatings was studied by QCM approach and human umbilical vein endothelial cell adhesion to coatings was examined. SiP to cross-linker weight ratios were varied from 2.0/0.5 to 9.0/0.5 (wt/wt%) and the coatings almost completely suppressed protein adsorption and cell adhesion to treated surfaces. The coating was also applied to polymeric films, rendering these materials biofouling-resistant.

  14. Irradiation-resistance conferred by superoxide dismutase: possible adaptive role of a natural polymorphism in Drosophila melanogaster

    SciTech Connect

    Peng, T.X.; Moya, A.; Ayala, F.J.

    1986-02-01

    The toxic effects of ionizing radiation to DNA are thought to be due to the generation of the superoxide radical, 02-. Superoxide dismutase (SOD), which scavenges 02-., has been invoked as a protecting enzyme against ionizing radiation in viruses, bacteria, mammalian cells in culture, and live mice. We now demonstrate that SOD is involved in the resistance of Drosophila melanogaster against irradiation. The protection is greatest when flies carry the S form of the enzyme (which exhibits highest in vitro specific activity), intermediate when they carry the F form of the enzyme, and lowest when they are homozygous for N, an allele that reduces the amount of the enzyme to 3.5% of the normal level. Natural selection experiments show that the fitness of the high-activity S allele is increased in an irradiated population relative to the nonirradiated control. These results point towards a possible adaptive function of the S/F polymorphism found in natural populations of D. melanogaster.

  15. Resistance to Bacillus thuringiensis Toxin Cry2Ab in Trichoplusia ni Is Conferred by a Novel Genetic Mechanism.

    PubMed

    Song, Xiaozhao; Kain, Wendy; Cassidy, Douglas; Wang, Ping

    2015-08-01

    The resistance to the Bacillus thuringiensis (Bt) toxin Cry2Ab in a greenhouse-originated Trichoplusia ni strain resistant to both Bt toxins Cry1Ac and Cry2Ab was characterized. Biological assays determined that the Cry2Ab resistance in the T. ni strain was a monogenic recessive trait independent of Cry1Ac resistance, and there existed no significant cross-resistance between Cry1Ac and Cry2Ab in T. ni. From the dual-toxin-resistant T. ni strain, a strain resistant to Cry2Ab only was isolated, and the Cry2Ab resistance trait was introgressed into a susceptible laboratory strain to facilitate comparative analysis of the Cry2Ab resistance with the susceptible T. ni strain. Results from biochemical analysis showed no significant difference between the Cry2Ab-resistant and -susceptible T. ni larvae in midgut proteases, including caseinolytic proteolytic activity and zymogram profile and serine protease activities, in midgut aminopeptidase and alkaline phosphatase activity, and in midgut esterases and hemolymph plasma melanization activity. For analysis of genetic linkage of Cry2Ab resistance with potential Cry toxin receptor genes, molecular markers for the midgut cadherin, alkaline phosphatase (ALP), and aminopeptidase N (APN) genes were identified between the original greenhouse-derived dual-toxin-resistant and the susceptible laboratory T. ni strains. Genetic linkage analysis showed that the Cry2Ab resistance in T. ni was not genetically associated with the midgut genes coding for the cadherin, ALP, and 6 APNs (APN1 to APN6) nor associated with the ABC transporter gene ABCC2. Therefore, the Cry2Ab resistance in T. ni is conferred by a novel but unknown genetic mechanism.

  16. Resistance to Bacillus thuringiensis Toxin Cry2Ab in Trichoplusia ni Is Conferred by a Novel Genetic Mechanism

    PubMed Central

    Song, Xiaozhao; Kain, Wendy; Cassidy, Douglas

    2015-01-01

    The resistance to the Bacillus thuringiensis (Bt) toxin Cry2Ab in a greenhouse-originated Trichoplusia ni strain resistant to both Bt toxins Cry1Ac and Cry2Ab was characterized. Biological assays determined that the Cry2Ab resistance in the T. ni strain was a monogenic recessive trait independent of Cry1Ac resistance, and there existed no significant cross-resistance between Cry1Ac and Cry2Ab in T. ni. From the dual-toxin-resistant T. ni strain, a strain resistant to Cry2Ab only was isolated, and the Cry2Ab resistance trait was introgressed into a susceptible laboratory strain to facilitate comparative analysis of the Cry2Ab resistance with the susceptible T. ni strain. Results from biochemical analysis showed no significant difference between the Cry2Ab-resistant and -susceptible T. ni larvae in midgut proteases, including caseinolytic proteolytic activity and zymogram profile and serine protease activities, in midgut aminopeptidase and alkaline phosphatase activity, and in midgut esterases and hemolymph plasma melanization activity. For analysis of genetic linkage of Cry2Ab resistance with potential Cry toxin receptor genes, molecular markers for the midgut cadherin, alkaline phosphatase (ALP), and aminopeptidase N (APN) genes were identified between the original greenhouse-derived dual-toxin-resistant and the susceptible laboratory T. ni strains. Genetic linkage analysis showed that the Cry2Ab resistance in T. ni was not genetically associated with the midgut genes coding for the cadherin, ALP, and 6 APNs (APN1 to APN6) nor associated with the ABC transporter gene ABCC2. Therefore, the Cry2Ab resistance in T. ni is conferred by a novel but unknown genetic mechanism. PMID:26025894

  17. Fine mapping of QTL and genomic prediction using allele-specific expression SNPs demonstrates that the complex trait of genetic resistance to Marek’s disease is predominantly determined by transcriptional regulation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The hypothesis that polymorphisms associated with transcriptional regulation are critical for viral disease resistance was tested by selecting birds using SNPs exhibiting allele-specific expression (ASE) in response to viral challenge. Analysis indicates ASE markers account for 83% of the disease re...

  18. The Brassica napus receptor-like protein RLM2 is encoded by a second allele of the LepR3/Rlm2 blackleg resistance locus.

    PubMed

    Larkan, Nicholas J; Ma, Lisong; Borhan, Mohammad Hossein

    2015-09-01

    Leucine-rich repeat receptor-like proteins (LRR-RLPs) are highly adaptable parts of the signalling apparatus for extracellular detection of plant pathogens. Resistance to blackleg disease of Brassica spp. caused by Leptosphaeria maculans is largely governed by host race-specific R-genes, including the LRR-RLP gene LepR3. The blackleg resistance gene Rlm2 was previously mapped to the same genetic interval as LepR3. In this study, the LepR3 locus of the Rlm2 Brassica napus line 'Glacier DH24287' was cloned, and B. napus transformants were analysed for recovery of the Rlm2 phenotype. Multiple B. napus, B. rapa and B. juncea lines were assessed for sequence variation at the locus. Rlm2 was found to be an allelic variant of the LepR3 LRR-RLP locus, conveying race-specific resistance to L. maculans isolates harbouring AvrLm2. Several defence-related LRR-RLPs have previously been shown to associate with the RLK SOBIR1 to facilitate defence signalling. Bimolecular fluorescence complementation (BiFC) and co-immunoprecipitation of RLM2-SOBIR1 studies revealed that RLM2 interacts with SOBIR1 of Arabidopsis thaliana when co-expressed in Nicotiana benthamiana. The interaction of RLM2 with AtSOBIR1 is suggestive of a conserved defence signalling pathway between B. napus and its close relative A. thaliana.

  19. Frequency of the delta ccr5 deletion allele in the urban Brazilian population.

    PubMed

    Passos, G A; Picanço, V P

    1998-04-01

    Studies on screening genes conferring resistance to HIV-1 and AIDS onset have shown a direct relationship between a 32 base pair (bp) deletion in the CCR5 beta-chemokine receptor gene (delta ccr5 mutant allele) and long survival of HIV-1 infected individuals bearing this mutation. These findings led to an interest in studies of delta ccr5 allele distribution in human populations. In the present study, polymerase chain reactions (PCR) in genomic DNA samples, using specific CCR5 oligonucleotide primers surrounding the breakpoint deletion, detected a 193-bp product from the normal CCR5 allele and a 161-bp product from the 32-bp deletion allele. In an investigation of the urban Brazilian population we detected a 93% frequency of normal CCR5/CCR5 homozygous individuals and a 7% frequency of CCR5/delta ccr5 heterozygous individuals. The frequency of the delta ccr5 mutant allele in this population is 0.035; however, no homozygous delta ccr5 individual has been detected thus far. This is the first evidence for the contribution of the delta ccr5 allele to the genetic background of the urban Brazilian population, which is characterized by intense ethnic admixture. These findings open perspectives for further studies on the relationship between delta ccr5 allele frequency and AIDS onset in high-risk HIV-1 exposures individuals.

  20. A novel fexA variant from a canine Staphylococcus pseudintermedius isolate that does not confer florfenicol resistance.

    PubMed

    Gómez-Sanz, Elena; Kadlec, Kristina; Feßler, Andrea T; Zarazaga, Myriam; Torres, Carmen; Schwarz, Stefan

    2013-11-01

    Transposon Tn558 integrated in the chromosomal radC gene was detected for the first time in Staphylococus pseudintermedius. It carried a novel fexA variant (fexAv) that confers only chloramphenicol resistance. The exporter FexAv exhibited two amino acid substitutions, Gly33Ala and Ala37Val, both of which seem to be important for substrate recognition. Site-directed mutagenesis that reverted the mutated base pairs to those present in the original fexA gene restored the chloramphenicol-plus-florfenicol resistance phenotype.

  1. A Novel FexA Variant from a Canine Staphylococcus pseudintermedius Isolate That Does Not Confer Florfenicol Resistance

    PubMed Central

    Gómez-Sanz, Elena; Kadlec, Kristina; Feßler, Andrea T.; Zarazaga, Myriam; Schwarz, Stefan

    2013-01-01

    Transposon Tn558 integrated in the chromosomal radC gene was detected for the first time in Staphylococus pseudintermedius. It carried a novel fexA variant (fexAv) that confers only chloramphenicol resistance. The exporter FexAv exhibited two amino acid substitutions, Gly33Ala and Ala37Val, both of which seem to be important for substrate recognition. Site-directed mutagenesis that reverted the mutated base pairs to those present in the original fexA gene restored the chloramphenicol-plus-florfenicol resistance phenotype. PMID:23979755

  2. Gastrodia anti-fungal protein from the orchid Gastrodia elata confers disease resistance to root pathogens in transgenic tobacco.

    PubMed

    Cox, K D; Layne, D R; Scorza, R; Schnabel, G

    2006-11-01

    Diseases of agricultural crops are caused by pathogens from several higher-order phylogenetic lineages including fungi, straminipila, eubacteria, and metazoa. These pathogens are commonly managed with pesticides due to the lack of broad-spectrum host resistance. Gastrodia anti-fungal protein (GAFP; gastrodianin) may provide a level of broad-spectrum resistance due to its documented anti-fungal activity in vitro and structural similarity to insecticidal lectins. We transformed tobacco (Nicotiana tabacum cv. Wisconsin 38) with GAFP-1 and challenged transformants with agriculturally important plant pathogens from several higher-order lineages including Rhizoctonia solani (fungus), Phytophthora nicotianae (straminipile), Ralstonia solanacearum (eubacterium), and Meloidogyne incognita (metazoan). Quantitative real-time PCR and western blotting analysis indicated that GAFP-1 was transcribed and translated in transgenic lines. When challenged by R. solani and P. nicotianae, GAFP-1 expressing lines had reduced symptom development and improved plant vigor compared to non-transformed and empty vector control lines. These lines also exhibited reduced root galling when challenged by M. incognita. Against R. solanacearum expression of GAFP-1 neither conferred resistance, nor exacerbated disease development. These results indicate that heterologous expression of GAFP-1 can confer enhanced resistance to a diverse set of plant pathogens and may be a good candidate gene for the development of transgenic, root-disease-resistant crops.

  3. Loss of cAMP/CRP regulation confers extreme high hydrostatic pressure resistance in Escherichia coli O157:H7.

    PubMed

    Vanlint, Dietrich; Pype, Brecht J Y; Rutten, Nele; Vanoirbeek, Kristof G A; Michiels, Chris W; Aertsen, Abram

    2013-08-16

    Application of high hydrostatic pressure (HHP) constitutes a valuable non-thermal pasteurization process in modern food conservation. Triggered by our interest in the rapid adaptive evolution towards HHP resistance in the food-borne pathogen E. coli O157:H7 (strain ATCC 43888) that was demonstrated earlier, we used genetic screening to identify specific loci in which a loss-of-function mutation would be sufficient to markedly increase HHP survival. As such, individual loss of RssB (anti RpoS-factor), CRP (catabolite response protein) and CyaA (adenylate cyclase) were each found to confer significant HHP resistance in the 300MPa range (i.e. >1,000-fold), and this phenotype invariably coincided with increased resistance against heat as well. In contrast to loss of RssB, however, loss of CRP or CyaA also conferred significantly increased resistance to 600MPa (i.e. >10,000-fold), suggesting cAMP/CRP homeostasis to affect extreme HHP resistance independently of increased RpoS activity. Surprisingly, none of the rapidly emerging HHP-resistant mutants of ATCC 43888 that were isolated previously did incur any mutations in rssB, crp or cyaA, indicating that a number of other loci can guide the rapid emergence of HHP resistance in E. coli O157:H7 as well. The inability of spontaneous rssB, crp or cyaA mutants to emerge during selective enrichment under HHP selection likely stems from their decreased competitive fitness during growth. Overall, this study is the first to shed light on the possible genetic strategies supporting the acquisition of HHP resistance in E. coli O157:H7.

  4. Overexpression of Salmonella enterica serovar Typhi recA gene confers fluoroquinolone resistance in Escherichia coli DH5α

    PubMed Central

    Yassien, M.A.M.; Elfaky, M.A.

    2015-01-01

    A spontaneous fluoroquinolone-resistant mutant (STM1) was isolated from its parent Salmonella enterica serovar Typhi (S. Typhi) clinical isolate. Unlike its parent isolate, this mutant has selective resistance to fluoroquinolones without any change in its sensitivity to various other antibiotics. DNA gyrase assays revealed that the fluoroquinolone resistance phenotype of the STM1 mutant did not result from alteration of the fluoroquinolone sensitivity of the DNA gyrase isolated from it. To study the mechanism of fluoroquinolone resistance, a genomic library from the STM1 mutant was constructed in Escherichia coli DH5α and two recombinant plasmids were obtained. Only one of these plasmids (STM1-A) conferred the selective fluoroquinolone resistance phenotype to E. coli DH5α. The chromosomal insert from STM1-A, digested with EcoRI and HindIII restriction endonucleases, produced two DNA fragments and these were cloned separately into pUC19 thereby generating two new plasmids, STM1-A1 and STM1-A2. Only STM1-A1 conferred the selective fluoroquinolone resistance phenotype to E. coli DH5α. Sequence and subcloning analyses of STM1-A1 showed the presence of an intact RecA open reading frame. Unlike that of the wild-type E. coli DH5α, protein analysis of a crude STM1-A1 extract showed overexpression of a 40 kDa protein. Western blotting confirmed the 40 kDa protein band to be RecA. When a RecA PCR product was cloned into pGEM-T and introduced into E. coli DH5α, the STM1-A11 subclone retained fluoroquinolone resistance. These results suggest that overexpression of RecA causes selective fluoroquinolone resistance in E. coli DH5α. PMID:26375447

  5. The Batten disease gene CLN3 confers resistance to endoplasmic reticulum stress induced by tunicamycin

    SciTech Connect

    Wu, Dan; Liu, Jing; Wu, Baiyan; Tu, Bo; Zhu, Weiguo; Luo, Jianyuan

    2014-04-25

    Highlights: • The work reveals a protective properties of CLN3 towards TM-induced apoptosis. • CLN3 regulates expression of the GRP78 and the CHOP in response to the ER stress. • CLN3 plays a specific role in the ERS response. - Abstract: Mutations in CLN3 gene cause juvenile neuronal ceroid lipofuscinosis (JNCL or Batten disease), an early-onset neurodegenerative disorder that is characterized by the accumulation of ceroid lipofuscin within lysosomes. The function of the CLN3 protein remains unclear and is presumed to be related to Endoplasmic reticulum (ER) stress. To investigate the function of CLN3 in the ER stress signaling pathway, we measured proliferation and apoptosis in cells transfected with normal and mutant CLN3 after treatment with the ER stress inducer tunicamycin (TM). We found that overexpression of CLN3 was sufficient in conferring increased resistance to ER stress. Wild-type CLN3 protected cells from TM-induced apoptosis and increased cell proliferation. Overexpression of wild-type CLN3 enhanced expression of the ER chaperone protein, glucose-regulated protein 78 (GRP78), and reduced expression of the proapoptotic protein CCAAT/-enhancer-binding protein homologous protein (CHOP). In contrast, overexpression of mutant CLN3 or siRNA knockdown of CLN3 produced the opposite effect. Together, our data suggest that the lack of CLN3 function in cells leads to a failure of management in the response to ER stress and this may be the key deficit in JNCL that causes neuronal degeneration.

  6. Tbx2 confers poor prognosis in glioblastoma and promotes temozolomide resistance with change of mitochondrial dynamics

    PubMed Central

    Yi, Fuxin; Du, Jianzhou; Ni, Weimin; Liu, Weixian

    2017-01-01

    Tbx2 is a cancer-related protein that was found to be overexpressed in several human malignancies. The present study aims to investigate the clinical significance and biological role of Tbx2 in human astrocytoma. We examined its protein expression in 102 cases of astrocytoma tissues using immunohistochemical staining. Negative Tbx2 staining was observed in normal astrocytes, and positive nuclear staining was found in 41 out of 102 astrocytoma specimens. The rate of Tbx2 overexpression in pylocytic astrocytoma, diffuse astrocytoma, anaplastic astrocytoma, and glioblastoma multiform (GBM) were 0%, 26.1%, 40%, and 52%, respectively. Tbx2 overexpression correlated with poor prognosis in patients with astrocytoma or GBM. Tbx2 plasmid transfection was performed in A172 cells, and Tbx2 siRNA knockdown was carried out in U251 cells. Cell Counting Kit-8, cell cycle analysis, and matrigel invasion assay showed that Tbx2 overexpression upregulated cell proliferation, G1-S transition, and invasion, with corresponding change of cyclin D1, p21, and MMP 2 and 9. Importantly, we demonstrated that Tbx2 reduced apoptosis and conferred resistance to temozolomide in GBM cell lines. Further experiments showed that Tbx2 could regulate mitochondrial fission/fusion balance. Western blot showed that Tbx2 overexpression reduced caspase 3 cleavage, while it induced Bcl-2 and p-Drp1 upregulation. In conclusion, our results indicated that Tbx2 might serve as an indicator for poor prognosis and also be useful as an important therapeutic in human GBM, which inhibits apoptosis through regulation of mitochondrial function. PMID:28260920

  7. Transgenic cotton expressing Cry10Aa toxin confers high resistance to the cotton boll weevil.

    PubMed

    Ribeiro, Thuanne Pires; Arraes, Fabricio Barbosa Monteiro; Lourenço-Tessutti, Isabela Tristan; Silva, Marilia Santos; Lisei-de-Sá, Maria Eugênia; Lucena, Wagner Alexandre; Macedo, Leonardo Lima Pepino; Lima, Janaina Nascimento; Santos Amorim, Regina Maria; Artico, Sinara; Alves-Ferreira, Márcio; Mattar Silva, Maria Cristina; Grossi-de-Sa, Maria Fatima

    2017-01-12

    Genetically modified (GM) cotton plants that effectively control cotton boll weevil (CBW), which is the most destructive cotton insect pest in South America, are reported here for the first time. This work presents the successful development of a new GM cotton with high resistance to CBW conferred by Cry10Aa toxin, a protein encoded by entomopathogenic Bacillus thuringiensis (Bt) gene. The plant transformation vector harbouring cry10Aa gene driven by the cotton ubiquitination-related promoter uceA1.7 was introduced into a Brazilian cotton cultivar by biolistic transformation. Quantitative PCR (qPCR) assays revealed high transcription levels of cry10Aa in both T0 GM cotton leaf and flower bud tissues. Southern blot and qPCR-based 2(-ΔΔCt) analyses revealed that T0 GM plants had either one or two transgene copies. Quantitative and qualitative analyses of Cry10Aa protein expression showed variable protein expression levels in both flower buds and leaves tissues of T0 GM cotton plants, ranging from approximately 3.0 to 14.0 μg g(-1) fresh tissue. CBW susceptibility bioassays, performed by feeding adults and larvae with T0 GM cotton leaves and flower buds, respectively, demonstrated a significant entomotoxic effect and a high level of CBW mortality (up to 100%). Molecular analysis revealed that transgene stability and entomotoxic effect to CBW were maintained in T1 generation as the Cry10Aa toxin expression levels remained high in both tissues, ranging from 4.05 to 19.57 μg g(-1) fresh tissue, and the CBW mortality rate remained around 100%. In conclusion, these Cry10Aa GM cotton plants represent a great advance in the control of the devastating CBW insect pest and can substantially impact cotton agribusiness.

  8. Identification of regulated genes conferring resistance to high concentrations of glyphosate in a new strain of Enterobacter.

    PubMed

    Fei, Yun-Yan; Gai, Jun-Yi; Zhao, Tuan-Jie

    2013-12-01

    Glyphosate is a widely used herbicide that inhibits 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) activity. Most plants and microbes are sensitive to glyphosate. However, transgenic-resistant crops that contain a modified epsps obtained from the resistant microbes have been commercially successful and therefore, new resistance genes and their adaptive regulatory mechanisms are of great interest. In this study, a soil-borne, glyphosate-resistant bacterium was selected and identified as Enterobacter. The EPSPS in this strain was found to have been altered to a resistant one. A total of 42 differentially expressed genes (DEGs) in the glyphosate were screened using microarray techniques. Under treatment, argF, sdhA, ivbL, rrfA-H were downregulated, whereas the transcripts of speA, osmY, pflB, ahpC, fusA, deoA, uxaC, rpoD and a few ribosomal protein genes were upregulated. Data were verified by quantitative real-time PCR on selected genes. All transcriptional changes appeared to protect the bacteria from glyphosate and associated osmotic, acidic and oxidative stresses. Many DEGs may have the potential to confer resistance to glyphosate alone, and some may be closely related to the shikimate pathway, reflecting the complex gene interaction network for glyphosate resistance.

  9. Linked, if not the same, Mi-1 homologues confer resistance to tomato powdery mildew and root-knot nematodes.

    PubMed

    Seifi, Alireza; Kaloshian, Isgouhi; Vossen, Jack; Che, Daidi; Bhattarai, Kishor K; Fan, Junmei; Naher, Zabun; Goverse, Aska; Tjallingii, W Freddy; Lindhout, Pim; Visser, Richard G F; Bai, Yuling

    2011-04-01

    On the short arm of tomato chromosome 6, a cluster of disease resistance (R) genes have evolved harboring the Mi-1 and Cf genes. The Mi-1 gene confers resistance to root-knot nematodes, aphids, and whiteflies. Previously, we mapped two genes, Ol-4 and Ol-6, for resistance to tomato powdery mildew in this cluster. The aim of this study was to investigate whether Ol-4 and Ol-6 are homologues of the R genes located in this cluster. We show that near-isogenic lines (NIL) harboring Ol-4 (NIL-Ol-4) and Ol-6 (NIL-Ol-6) are also resistant to nematodes and aphids. Genetically, the resistance to nematodes cosegregates with Ol-4 and Ol-6, which are further fine-mapped to the Mi-1 cluster. We provide evidence that the composition of Mi-1 homologues in NIL-Ol-4 and NIL-Ol-6 is different from other nematode-resistant tomato lines, Motelle and VFNT, harboring the Mi-1 gene. Furthermore, we demonstrate that the resistance to both nematodes and tomato powdery mildew in these two NIL is governed by linked (if not the same) Mi-1 homologues in the Mi-1 gene cluster. Finally, we discuss how Solanum crops exploit Mi-1 homologues to defend themselves against distinct pathogens.

  10. The Fd-GOGAT1 mutant gene lc7 confers resistance to Xanthomonas oryzae pv. Oryzae in rice

    PubMed Central

    Chen, Honglin; Li, Chunrong; Liu, Liping; Zhao, Jiying; Cheng, Xuzhen; Jiang, Guanghuai; Zhai, Wenxue

    2016-01-01

    Disease resistance is an important goal of crop improvement. The molecular mechanism of resistance requires further study. Here, we report the identification of a rice leaf color mutant, lc7, which is defective in chlorophyll synthesis and photosynthesis but confers resistance to Xanthomonas oryzae pv. Oryzae (Xoo). Map-based cloning revealed that lc7 encodes a mutant ferredoxin-dependent glutamate synthase1 (Fd-GOGAT1). Fd-GOGAT1 has been proposed to have great potential for improving nitrogen-use efficiency, but its function in bacterial resistance has not been reported. The lc7 mutant accumulates excessive levels of ROS (reactive oxygen species) in the leaves, causing the leaf color to become yellow after the four-leaf stage. Compared to the wild type, lc7 mutants have a broad-spectrum high resistance to seven Xoo strains. Differentially expressed genes (DEGs) and qRT-PCR analysis indicate that many defense pathways that are involved in this broad-spectrum resistance are activated in the lc7 mutant. These results suggest that Fd-GOGAT1 plays an important role in broad-spectrum bacterial blight resistance, in addition to modulating nitrogen assimilation and chloroplast development. PMID:27211925

  11. Viral-inducible Argonaute18 confers broad-spectrum virus resistance in rice by sequestering a host microRNA.

    PubMed

    Wu, Jianguo; Yang, Zhirui; Wang, Yu; Zheng, Lijia; Ye, Ruiqiang; Ji, Yinghua; Zhao, Shanshan; Ji, Shaoyi; Liu, Ruofei; Xu, Le; Zheng, Hong; Zhou, Yijun; Zhang, Xin; Cao, Xiaofeng; Xie, Lianhui; Wu, Zujian; Qi, Yijun; Li, Yi

    2015-02-17

    Viral pathogens are a major threat to rice production worldwide. Although RNA interference (RNAi) is known to mediate antiviral immunity in plant and animal models, the mechanism of antiviral RNAi in rice and other economically important crops is poorly understood. Here, we report that rice resistance to evolutionarily diverse viruses requires Argonaute18 (AGO18). Genetic studies reveal that the antiviral function of AGO18 depends on its activity to sequester microRNA168 (miR168) to alleviate repression of rice AGO1 essential for antiviral RNAi. Expression of miR168-resistant AGO1a in ago18 background rescues or increases rice antiviral activity. Notably, stable transgenic expression of AGO18 confers broad-spectrum virus resistance in rice. Our findings uncover a novel cooperative antiviral activity of two distinct AGO proteins and suggest a new strategy for the control of viral diseases in rice.

  12. Functional expression of P-glycoprotein in Saccharomyces cerevisiae confers cellular resistance to the immunosuppressive and antifungal agent FK520.

    PubMed Central

    Raymond, M; Ruetz, S; Thomas, D Y; Gros, P

    1994-01-01

    We have recently reported that expression in yeast cells of P-glycoprotein (P-gp) encoded by the mouse multidrug resistance mdr3 gene (Mdr3) can complement a null ste6 mutation (M. Raymond, P. Gros, M. Whiteway, and D. Y. Thomas, Science 256:232-234, 1992). Here we show that Mdr3 behaves as a fully functional drug transporter in this heterologous expression system. Photolabelling experiments indicate that Mdr3 synthesized in yeast cells binds the drug analog [125I]iodoaryl azidoprazosin, this binding being competed for by vinblastine and tetraphenylphosphonium bromide, two known multidrug resistance drugs. Spheroplasts expressing wild-type Mdr3 (Ser-939) exhibit an ATP-dependent and verapamil-sensitive decreased accumulation of [3H]vinblastine as compared with spheroplasts expressing a mutant form of Mdr3 with impaired transport activity (Phe-939). Expression of Mdr3 in yeast cells can confer resistance to growth inhibition by the antifungal and immunosuppressive agent FK520, suggesting that this compound is a substrate for P-gp in yeast cells. Replacement of Ser-939 in Mdr3 by a series of amino acid substitutions is shown to modulate both the level of cellular resistance to FK520 and the mating efficiency of yeast mdr3 transformants. The effects of these mutations on the function of Mdr3 in yeast cells are similar to those observed in mammalian cells with respect to drug resistance and transport, indicating that transport of a-factor and FK520 in yeast cells is mechanistically similar to drug transport in mammalian cells. The ability of P-gp to confer cellular resistance to FK520 in yeast cells establishes a dominant phenotype that can be assayed for the positive selection of intragenic revertants of P-gp inactive mutants, an important tool for the structure-function analysis of mammalian P-gp in yeast cells. Images PMID:7505392

  13. Distinct Detoxification Mechanisms Confer Resistance to Mesotrione and Atrazine in a Population of Waterhemp1[C][W][OPEN

    PubMed Central

    Ma, Rong; Kaundun, Shiv S.; Tranel, Patrick J.; Riggins, Chance W.; McGinness, Daniel L.; Hager, Aaron G.; Hawkes, Tim; McIndoe, Eddie; Riechers, Dean E.

    2013-01-01

    Previous research reported the first case of resistance to mesotrione and other 4-hydroxyphenylpyruvate dioxygenase (HPPD) herbicides in a waterhemp (Amaranthus tuberculatus) population designated MCR (for McLean County mesotrione- and atrazine-resistant). Herein, experiments were conducted to determine if target site or nontarget site mechanisms confer mesotrione resistance in MCR. Additionally, the basis for atrazine resistance was investigated in MCR and an atrazine-resistant but mesotrione-sensitive population (ACR for Adams County mesotrione-sensitive but atrazine-resistant). A standard sensitive population (WCS for Wayne County herbicide-sensitive) was also used for comparison. Mesotrione resistance was not due to an alteration in HPPD sequence, HPPD expression, or reduced herbicide absorption. Metabolism studies using whole plants and excised leaves revealed that the time for 50% of absorbed mesotrione to degrade in MCR was significantly shorter than in ACR and WCS, which correlated with previous phenotypic responses to mesotrione and the quantity of the metabolite 4-hydroxy-mesotrione in excised leaves. The cytochrome P450 monooxygenase inhibitors malathion and tetcyclacis significantly reduced mesotrione metabolism in MCR and corn (Zea mays) excised leaves but not in ACR. Furthermore, malathion increased mesotrione activity in MCR seedlings in greenhouse studies. These results indicate that enhanced oxidative metabolism contributes significantly to mesotrione resistance in MCR. Sequence analysis of atrazine-resistant (MCR and ACR) and atrazine-sensitive (WCS) waterhemp populations detected no differences in the psbA gene. The times for 50% of absorbed atrazine to degrade in corn, MCR, and ACR leaves were shorter than in WCS, and a polar metabolite of atrazine was detected in corn, MCR, and ACR that cochromatographed with a synthetic atrazine-glutathione conjugate. Thus, elevated rates of metabolism via distinct detoxification mechanisms contribute to

  14. Stable expression of EBERs in immortalized nasopharyngeal epithelial cells confers resistance to apoptotic stress.

    PubMed

    Wong, Hing Lok; Wang, Xianghong; Chang, Raymond Chuen-Chung; Jin, Dong-Yan; Feng, Huichen; Wang, Qi; Lo, Kwok-Wai; Huang, Dolly P; Yuen, Po Wing; Takada, Kenzo; Wong, Yong Chuan; Tsao, Sai Wah

    2005-10-01

    Epstein-Barr virus (EBV) infection is closely associated with the development of nasopharyngeal carcinoma (NPC). The EBV-encoded RNAs (EBERs) are the most abundant EBV transcripts (about 10(7) copies per cell) in EBV infected cells. However, the cellular function of EBER expression, particularly in nasopharyngeal epithelial cells, remains poorly understood. EBERs acquire secondary structures analogous to double-stranded RNA (dsRNA) and may bind to the double-stranded RNA-dependent protein kinase (PKR) and interfere with its function. Activation of PKR involves autophosphorylation resulting in protein synthesis inhibition and cellular apoptosis. Induction of cellular apoptosis by activation of PKR may be an antiviral response adopted by virally infected cells. We have examined the functional properties of EBER expression in an immortalized nasopharyngeal epithelial cell line (NP69). Expression of EBERs was achieved by transfecting the NP69 cells with an EBER-expressing plasmid, pESK10. The EBER-expressing NP69 cells attained a higher growth rate compared to cells transfected with control plasmid (pcDNA3). However, the EBER-expressing NP69 cells did not form colonies in soft agar and were non-tumorigenic in nude mice. To investigate if EBERs may protect the nasopharyngeal epithelial cells from apoptotic insults, we treated the EBER-expressing NP69 cells with a dsRNA analogue, poly(I).poly(C) (pIC), to activate PKR in cells and examined for their responses. Lower level of PKR phosphorylation and elevation of Bcl-2 were observed in EBER-expressing NP69 cells. In addition, other apoptotic markers including the cleaved forms of caspase-3 and poly(ADP)ribose polymerase (PARP) were found to be lower in EBER-expressing NP69 cells after treatment with pIC. Lower phosphorylation levels of p38 MAPK (mitogen-activated protein kinase) and c-jun were also observed in EBER-expressing NP cells. Our results suggest that EBER expression may confer an apoptotic-resistant phenotype in

  15. Acquired resistance to dasatinib in lung cancer cell lines conferred by DDR2 gatekeeper mutation and NF1 loss.

    PubMed

    Beauchamp, Ellen M; Woods, Brittany A; Dulak, Austin M; Tan, Li; Xu, Chunxiao; Gray, Nathanael S; Bass, Adam J; Wong, Kwok-kin; Meyerson, Matthew; Hammerman, Peter S

    2014-02-01

    The treatment of non-small cell lung cancer has evolved dramatically over the past decade with the adoption of widespread use of effective targeted therapies in patients with distinct molecular alterations. In lung squamous cell carcinoma (lung SqCC), recent studies have suggested that DDR2 mutations are a biomarker for therapeutic response to dasatinib and clinical trials are underway testing this hypothesis. Although targeted therapeutics are typically quite effective as initial therapy for patients with lung cancer, nearly all patients develop resistance with long-term exposure to targeted drugs. Here, we use DDR2-dependent lung cancer cell lines to model acquired resistance to dasatinib therapy. We perform targeted exome sequencing to identify two distinct mechanisms of acquired resistance: acquisition of the T654I gatekeeper mutation in DDR2 and loss of NF1. We show that NF1 loss activates a bypass pathway, which confers ERK dependency downstream of RAS activation. These results indicate that acquired resistance to dasatinib can occur via both second-site mutations in DDR2 and by activation of bypass pathways. These data may help to anticipate mechanisms of resistance that may be identified in upcoming clinical trials of anti-DDR2 therapy in lung cancer and suggest strategies to overcome resistance.

  16. Development of pyramidal lines with two major QTLs conferring resistance to sheath blight in rice (Oryza sativa L.)

    NASA Astrophysics Data System (ADS)

    Hossain, Md Kamal; Jena, Kshirod; Bhuiyan, Md Atiqur Rahman; Ratnam, Wickneswari

    2014-09-01

    Sheath blight is an emerging threat in rice cultivation. It is animportant disease caused by the soil-borne necrotrophic pathogenic fungus, Rhizoctonia solani Kühn. However, to date neither known major genes for quantitative resistance, nor any rice lines immune to this disease has been identified. The disease resistance is quantitative in nature. Numerous genes are involved in this resistance process. There are few quantitative trait loci (QTLs) detected conferring improved resistance against the disease. Teqing and Tetepshowimproved resistance having QTLs, qSB-9 and qSBR11-1, respectively. Since, these QTLs demonstrates additive effects, pyramiding of these QTLs might be an option to increase the sheath blight resistance in rice. Nine rice cultivars were screened at greenhouse conditions. Results showed that Tetep and Teqing had the lowest disease ratings. UKMRC2a new high yielding cultivar was as recipient parent. Crosses between UKMRC2 and Teqing, and UKMRC2 and Tetep were made and confirmed. Subsequently 4-way crosses between the two F1s were performed to develop pyramidal lines.

  17. Characterization of Small ColE1-Like Plasmids Conferring Kanamycin Resistance in Salmonella enterica subsp. enterica serovars Typhimurium and Newport

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Multi-antibiotic resistant (MR) Salmonella enterica serovars Typhimurium and Newport are an increasing concern in human and animal health. Many strains are known to carry antibiotic resistance determinants on multiple plasmids, yet detailed information is scarce. Three plasmids conferring kanamycin...

  18. Gene-specific markers for the wheat gene Lr34/Yr18/Pm38 which confers resistance to multiple fungal pathogens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The locus Lr34/Yr18/Pm38 confers partial and durable resistance against the devastating fungal pathogens leaf rust, stripe rust, and powdery mildew. In previous studies, this broad-spectrum resistance was shown to be controlled by a single gene which encodes a putative ATP-binding cassette transport...

  19. Characterization and mapping of Rpi1, a gene that confers dominant resistance to stalk rot in maize.

    PubMed

    Yang, D E; Jin, D M; Wang, B; Zhang, D S; Nguyen, H-T; Zhang, C L; Chen, S J

    2005-10-01

    The maize inbred lines 1145 (resistant) and Y331 (susceptible), and the F(1), F(2) and BC(1)F(1) populations derived from them were inoculated with the pathogen Pythium inflatum Matthews, which causes stalk rot in Zea mays. Field data revealed that the ratio of resistant to susceptible plants was 3:1 in the F(2) population, and 1:1 in the BC(1)F(1)population, indicating that the resistance to P. inflatum Matthews was controlled by a single dominant gene in the 1145xY331 cross. The gene that confers resistance to P. inflatum Matthews was designated Rpi1 for resistance to P. inflatum) according to the standard nomenclature for plant disease resistance genes. Fifty SSR markers from 10 chromosomes were first screened in the F(2) population to find markers linked to the Rpi1 gene. The results indicated that umc1702 and mmc0371 were both linked to Rpi1, placing the resistance gene on chromosome 4. RAPD (randomly amplified polymorphic DNA) markers were then tested in the F(2)population using bulked segregant analysis (BSA). Four RAPD products were found to show linkage to the Rpi1 gene. Then 27 SSR markers and 8 RFLP markers in the region encompassing Rpi1 were used for fine-scale mapping of the resistance gene. Two SSR markers and four RFLP markers were linked to the Rpi1 gene. Finally, the Rpi1 gene was mapped between the SSR markers bnlg1937 and agrr286 on chromosome 4, 1.6 cM away from the former and 4.1 cM distant from the latter. This is the first time that a dominant gene for resistance to maize stalk rot caused by P. inflatum Matthews has been mapped with molecular marker techniques.

  20. Overexpression of the D-alanine racemase gene confers resistance to D-cycloserine in Mycobacterium smegmatis.

    PubMed Central

    Cáceres, N E; Harris, N B; Wellehan, J F; Feng, Z; Kapur, V; Barletta, R G

    1997-01-01

    D-Cycloserine is an effective second-line drug against Mycobacterium avium and Mycobacterium tuberculosis. To analyze the genetic determinants of D-cycloserine resistance in mycobacteria, a library of a resistant Mycobacterium smegmatis mutant was constructed. A resistant clone harboring a recombinant plasmid with a 3.1-kb insert that contained the glutamate decarboxylase (gadA) and D-alanine racemase (alrA) genes was identified. Subcloning experiments demonstrated that alrA was necessary and sufficient to confer a D-cycloserine resistance phenotype. The D-alanine racemase activities of wild-type and recombinant M. smegmatis strains were inhibited by D-cycloserine in a concentration-dependent manner. The D-cycloserine resistance phenotype in the recombinant clone was due to the overexpression of the wild-type alrA gene in a multicopy vector. Analysis of a spontaneous resistant mutant also demonstrated overproduction of wild-type AlrA enzyme. Nucleotide sequence analysis of the overproducing mutant revealed a single transversion (G-->T) at the alrA promoter, which resulted in elevated beta-galactosidase reporter gene expression. Furthermore, transformants of Mycobacterium intracellulare and Mycobacterium bovis BCG carrying the M. smegmatis wild-type alrA gene in a multicopy vector were resistant to D-cycloserine, suggesting that AlrA overproduction is a potential mechanism of D-cycloserine resistance in clinical isolates of M. tuberculosis and other pathogenic mycobacteria. In conclusion, these results show that one of the mechanisms of D-cycloserine resistance in M. smegmatis involves the overexpression of the alrA gene due to a promoter-up mutation. PMID:9260945

  1. Mutation of Rv2887, a marR-Like Gene, Confers Mycobacterium tuberculosis Resistance to an Imidazopyridine-Based Agent

    PubMed Central

    Winglee, Kathryn; Lun, Shichun; Pieroni, Marco; Kozikowski, Alan

    2015-01-01

    Drug resistance is a major problem in Mycobacterium tuberculosis control, and it is critical to identify novel drug targets and new antimycobacterial compounds. We have previously identified an imidazo[1,2-a]pyridine-4-carbonitrile-based agent, MP-III-71, with strong activity against M. tuberculosis. In this study, we evaluated mechanisms of resistance to MP-III-71. We derived three independent M. tuberculosis mutants resistant to MP-III-71 and conducted whole-genome sequencing of these mutants. Loss-of-function mutations in Rv2887 were common to all three MP-III-71-resistant mutants, and we confirmed the role of Rv2887 as a gene required for MP-III-71 susceptibility using complementation. The Rv2887 protein was previously unannotated, but domain and homology analyses suggested it to be a transcriptional regulator in the MarR (multiple antibiotic resistance repressor) family, a group of proteins first identified in Escherichia coli to negatively regulate efflux pumps and other mechanisms of multidrug resistance. We found that two efflux pump inhibitors, verapamil and chlorpromazine, potentiate the action of MP-III-71 and that mutation of Rv2887 abrogates their activity. We also used transcriptome sequencing (RNA-seq) to identify genes which are differentially expressed in the presence and absence of a functional Rv2887 protein. We found that genes involved in benzoquinone and menaquinone biosynthesis were repressed by functional Rv2887. Thus, inactivating mutations of Rv2887, encoding a putative MarR-like transcriptional regulator, confer resistance to MP-III-71, an effective antimycobacterial compound that shows no cross-resistance to existing antituberculosis drugs. The mechanism of resistance of M. tuberculosis Rv2887 mutants may involve efflux pump upregulation and also drug methylation. PMID:26303802

  2. Protective effect of CCR5 Delta-32 allele against HIV-1 in Mexican women.

    PubMed

    Estrada-Aguirre, Jesús A; Cázarez-Salazar, Silvestre G; Ochoa-Ramírez, Luis A; Acosta-Cota, Selene de J; Zamora-Gómez, Román; Najar-Reyes, Guilermi M; Villarreal-Escamilla, Perla; Osuna-Ramírez, Ignacio; Díaz-Camacho, Sylvia P; Sánchez-Zazueta, Jorge G; Ríos-Tostado, Juan J; Velarde-Félix, Jesús S

    2013-09-01

    C-C chemokine receptor type 5 (CCR5) is known for its role as a co-receptor for HIV-1 infection. Some individuals possess a 32 bp deletion, known as Delta-32 allele which has been reported to confer resistance to HIV-1 infection. In order to estimate the distribution of Delta-32 allele of CCR5 gene, 1034 mestizo individuals from the Northwest of Mexico, including 385 HIV-1-infected individuals, 472 healthy controls and 177 uninfected female sex workers; were examined by allele-specific PCR. There was no statistically significant difference in the frequency of Delta-32 allele between HIV-1 positive and healthy individuals (OR= 1.1, p= 0.6). However, we found a significantly reduced prevalence of CCR5 Delta-32 heterozygous genotype in female patients (OR= 0.084, 95% CI= 0.011 - 0.630, p= 0.002), as well as in allele frequency, compared to male patients. Furthermore, we observed an inverse relationship between allele frequency and the risk of HIV-1 transmission and AIDS progression among female healthy controls, sex workers and HIV-1 infected groups. Our findings support previous data showing Delta-32 as a genetic protective factor against HIV-1 infection in Mexican women, as well as in women from other populations.

  3. Mutations in pepQ Confer Low-Level Resistance to Bedaquiline and Clofazimine in Mycobacterium tuberculosis

    PubMed Central

    Almeida, Deepak; Ioerger, Thomas; Tyagi, Sandeep; Li, Si-Yang; Mdluli, Khisimuzi; Andries, Koen; Grosset, Jacques; Sacchettini, Jim

    2016-01-01

    The novel ATP synthase inhibitor bedaquiline recently received accelerated approval for treatment of multidrug-resistant tuberculosis and is currently being studied as a component of novel treatment-shortening regimens for drug-susceptible and multidrug-resistant tuberculosis. In a limited number of bedaquiline-treated patients reported to date, ≥4-fold upward shifts in bedaquiline MIC during treatment have been attributed to non-target-based mutations in Rv0678 that putatively increase bedaquiline efflux through the MmpS5-MmpL5 pump. These mutations also confer low-level clofazimine resistance, presumably by a similar mechanism. Here, we describe a new non-target-based determinant of low-level bedaquiline and clofazimine cross-resistance in Mycobacterium tuberculosis: loss-of-function mutations in pepQ (Rv2535c), which corresponds to a putative Xaa-Pro aminopeptidase. pepQ mutants were selected in mice by treatment with clinically relevant doses of bedaquiline, with or without clofazimine, and were shown to have bedaquiline and clofazimine MICs 4 times higher than those for the parental H37Rv strain. Coincubation with efflux inhibitors verapamil and reserpine lowered bedaquiline MICs against both mutant and parent strains to a level below the MIC against H37Rv in the absence of efflux pump inhibitors. However, quantitative PCR (qPCR) revealed no significant differences in expression of Rv0678, mmpS5, or mmpL5 between mutant and parent strains. Complementation of a pepQ mutant with the wild-type gene restored susceptibility, indicating that loss of PepQ function is sufficient for reduced susceptibility both in vitro and in mice. Although the mechanism by which mutations in pepQ confer bedaquiline and clofazimine cross-resistance remains unclear, these results may have clinical implications and warrant further evaluation of clinical isolates with reduced susceptibility to either drug for mutations in this gene. PMID:27185800

  4. Mutations in pepQ Confer Low-Level Resistance to Bedaquiline and Clofazimine in Mycobacterium tuberculosis.

    PubMed

    Almeida, Deepak; Ioerger, Thomas; Tyagi, Sandeep; Li, Si-Yang; Mdluli, Khisimuzi; Andries, Koen; Grosset, Jacques; Sacchettini, Jim; Nuermberger, Eric

    2016-08-01

    The novel ATP synthase inhibitor bedaquiline recently received accelerated approval for treatment of multidrug-resistant tuberculosis and is currently being studied as a component of novel treatment-shortening regimens for drug-susceptible and multidrug-resistant tuberculosis. In a limited number of bedaquiline-treated patients reported to date, ≥4-fold upward shifts in bedaquiline MIC during treatment have been attributed to non-target-based mutations in Rv0678 that putatively increase bedaquiline efflux through the MmpS5-MmpL5 pump. These mutations also confer low-level clofazimine resistance, presumably by a similar mechanism. Here, we describe a new non-target-based determinant of low-level bedaquiline and clofazimine cross-resistance in Mycobacterium tuberculosis: loss-of-function mutations in pepQ (Rv2535c), which corresponds to a putative Xaa-Pro aminopeptidase. pepQ mutants were selected in mice by treatment with clinically relevant doses of bedaquiline, with or without clofazimine, and were shown to have bedaquiline and clofazimine MICs 4 times higher than those for the parental H37Rv strain. Coincubation with efflux inhibitors verapamil and reserpine lowered bedaquiline MICs against both mutant and parent strains to a level below the MIC against H37Rv in the absence of efflux pump inhibitors. However, quantitative PCR (qPCR) revealed no significant differences in expression of Rv0678, mmpS5, or mmpL5 between mutant and parent strains. Complementation of a pepQ mutant with the wild-type gene restored susceptibility, indicating that loss of PepQ function is sufficient for reduced susceptibility both in vitro and in mice. Although the mechanism by which mutations in pepQ confer bedaquiline and clofazimine cross-resistance remains unclear, these results may have clinical implications and warrant further evaluation of clinical isolates with reduced susceptibility to either drug for mutations in this gene.

  5. A Novel Glycolipid Biosurfactant Confers Grazing Resistance upon Pantoea ananatis BRT175 against the Social Amoeba Dictyostelium discoideum

    PubMed Central

    Smith, Derek D. N.; Nickzad, Arvin

    2016-01-01

    ABSTRACT Pantoea is a versatile genus of bacteria with both plant- and animal-pathogenic strains, some of which have been suggested to cause human infections. There is, however, limited knowledge on the potential determinants used for host association and pathogenesis in animal systems. In this study, we used the model host Dictyostelium discoideum to show that isolates of Pantoea ananatis exhibit differential grazing susceptibility, with some being resistant to grazing by the amoebae. We carried out a high-throughput genetic screen of one grazing-resistant isolate, P. ananatis BRT175, using the D. discoideum pathosystem to identify genes responsible for the resistance phenotype. Among the 26 candidate genes involved in grazing resistance, we identified rhlA and rhlB, which we show are involved in the biosynthesis of a biosurfactant that enables swarming motility in P. ananatis BRT175. Using liquid chromatography-mass spectrometry (LC-MS), the biosurfactant was shown to be a glycolipid with monohexose-C10-C10 as the primary congener. We show that this novel glycolipid biosurfactant is cytotoxic to the amoebae and is capable of compromising cellular integrity, leading to cell lysis. The production of this biosurfactant may be important for bacterial survival in the environment and could contribute to the establishment of opportunistic infections. IMPORTANCE The genetic factors used for host interaction by the opportunistic human pathogen Pantoea ananatis are largely unknown. We identified two genes that are important for the production of a biosurfactant that confers grazing resistance against the social amoeba Dictyostelium discoideum. We show that the biosurfactant, which exhibits cytotoxicity toward the amoebae, is a glycolipid that incorporates a hexose rather than rhamnose. The production of this biosurfactant may confer a competitive advantage in the environment and could potentially contribute to the establishment of opportunistic infections. PMID

  6. Ecological genomics of tropical trees: how local population size and allelic diversity of resistance genes relate to immune responses, cosusceptibility to pathogens, and negative density dependence.

    PubMed

    Marden, J H; Mangan, S A; Peterson, M P; Wafula, E; Fescemyer, H W; Der, J P; dePamphilis, C W; Comita, L S

    2017-01-02

    In tropical forests, rarer species show increased sensitivity to species-specific soil pathogens and more negative effects of conspecific density on seedling survival (NDD). These patterns suggest a connection between ecology and immunity, perhaps because small population size disproportionately reduces genetic diversity of hyperdiverse loci such as immunity genes. In an experiment examining seedling roots from six species in one tropical tree community, we found that smaller populations have reduced amino acid diversity in pathogen resistance (R) genes but not the transcriptome in general. Normalized R gene amino acid diversity varied with local abundance and prior measures of differences in sensitivity to conspecific soil and NDD. After exposure to live soil, species with lower R gene diversity had reduced defence gene induction, more cosusceptibility of maternal cohorts to colonization by potentially pathogenic fungi, reduced root growth arrest (an R gene-mediated response) and their root-associated fungi showed lower induction of self-defence (antioxidants). Local abundance was not related to the ability to induce immune responses when pathogen recognition was bypassed by application of salicylic acid, a phytohormone that activates defence responses downstream of R gene signalling. These initial results support the hypothesis that smaller local tree populations have reduced R gene diversity and recognition-dependent immune responses, along with greater cosusceptibility to species-specific pathogens that may facilitate disease transmission and NDD. Locally rare species may be less able to increase their equilibrium abundance without genetic boosts to defence via immigration of novel R gene alleles from a larger and more diverse regional population.

  7. Perspectives of a scrapie resistance breeding scheme targeting Q211, S146 and K222 caprine PRNP alleles in Greek goats.

    PubMed

    Kanata, Eirini; Humphreys-Panagiotidis, Cynthia; Giadinis, Nektarios D; Papaioannou, Nikolaos; Arsenakis, Minas; Sklaviadis, Theodoros

    2014-04-09

    The present study investigates the potential use of the scrapie-protective Q211 S146 and K222 caprine PRNP alleles as targets for selective breeding in Greek goats. Genotyping data from a high number of healthy goats with special emphasis on bucks, revealed high frequencies of these alleles, while the estimated probabilities of disease occurrence in animals carrying these alleles were low, suggesting that they can be used for selection. Greek goats represent one of the largest populations in Europe. Thus, the considerations presented here are an example of the expected effect of such a scheme on scrapie occurrence and on stakeholders.

  8. In Silico Assigned Resistance Genes Confer Bifidobacterium with Partial Resistance to Aminoglycosides but Not to Β-Lactams

    PubMed Central

    Fouhy, Fiona; O’Connell Motherway, Mary; Fitzgerald, Gerald F.; Ross, R. Paul; Stanton, Catherine; van Sinderen, Douwe; Cotter, Paul D.

    2013-01-01

    Bifidobacteria have received significant attention due to their contribution to human gut health and the use of specific strains as probiotics. It is thus not surprising that there has also been significant interest with respect to their antibiotic resistance profile. Numerous culture-based studies have demonstrated that bifidobacteria are resistant to the majority of aminoglycosides, but are sensitive to β-lactams. However, limited research exists with respect to the genetic basis for the resistance of bifidobacteria to aminoglycosides. Here we performed an in-depth in silico analysis of putative Bifidobacterium-encoded aminoglycoside resistance proteins and β-lactamases and assess the contribution of these proteins to antibiotic resistance. The in silico-based screen detected putative aminoglycoside and β-lactam resistance proteins across the Bifidobacterium genus. Laboratory-based investigations of a number of representative bifidobacteria strains confirmed that despite containing putative β-lactamases, these strains were sensitive to β-lactams. In contrast, all strains were resistant to the aminoglycosides tested. To assess the contribution of genes encoding putative aminoglycoside resistance proteins in Bifidobacterium sp. two genes, namely Bbr_0651 and Bbr_1586, were targeted for insertional inactivation in B. breve UCC2003. As compared to the wild-type, the UCC2003 insertion mutant strains exhibited decreased resistance to gentamycin, kanamycin and streptomycin. This study highlights the associated risks of relying on the in silico assignment of gene function. Although several putative β-lactam resistance proteins are located in bifidobacteria, their presence does not coincide with resistance to these antibiotics. In contrast however, this approach has resulted in the identification of two loci that contribute to the aminoglycoside resistance of B. breve UCC2003 and, potentially, many other bifidobacteria. PMID:24324818

  9. Antisense expression of peach mildew resistance locus O (PpMlo1) gene confers cross-species resistance to powdery mildew in Fragaria x ananassa.

    PubMed

    Jiwan, Derick; Roalson, Eric H; Main, Dorrie; Dhingra, Amit

    2013-12-01

    Powdery mildew (PM) is one of the major plant pathogens. The conventional method of PM control includes frequent use of sulfur-based fungicides adding to production costs and potential harm to the environment. PM remains a major scourge for Rosaceae crops where breeding approaches mainly resort to gene-for-gene resistance. We have tested an alternate source of PM resistance in Rosaceae. Mildew resistance locus O (MLO) has been well studied in barley due to its role in imparting broad spectrum resistance to PM. We identified PpMlo1 (Prunus persica Mlo) in peach and characterized it further to test if a similar mechanism of resistance is conserved in Rosaceae. Due to its recalcitrance in tissue culture, reverse genetic studies involving PpMloI were not feasible in peach. Therefore, Fragaria x ananassa LF9 line, a taxonomic surrogate, was used for functional analysis of PpMlo1. Agrobacterium-mediated transformation yielded transgenic strawberry plants expressing PpMlo1 in sense and antisense orientation. Antisense expression of PpMlo1 in transgenic strawberry plants conferred resistance to Fragaria-specific powdery mildew, Podosphaera macularis. Phylogenetic analysis of 208 putative Mlo gene copies from 35 plant species suggests a large number of duplications of this gene family prior to the divergence of monocots and eudicots, early in eudicot diversification. Our results indicate that the Mlo-based resistance mechanism is functional in Rosaceae, and that Fragaria can be used as a host to test mechanistic function of genes derived from related tree species. To the best of our knowledge, this work is one of the first attempts at testing the potential of using a Mlo-based resistance strategy to combat powdery mildew in Rosaceae.

  10. TRIB2 confers resistance to anti-cancer therapy by activating the serine/threonine protein kinase AKT

    PubMed Central

    Hill, Richard; Madureira, Patricia A.; Ferreira, Bibiana; Baptista, Inês; Machado, Susana; Colaço, Laura; dos Santos, Marta; Liu, Ningshu; Dopazo, Ana; Ugurel, Selma; Adrienn, Angyal; Kiss-Toth, Endre; Isbilen, Murat; Gure, Ali O.; Link, Wolfgang

    2017-01-01

    Intrinsic and acquired resistance to chemotherapy is the fundamental reason for treatment failure for many cancer patients. The identification of molecular mechanisms involved in drug resistance or sensitization is imperative. Here we report that tribbles homologue 2 (TRIB2) ablates forkhead box O activation and disrupts the p53/MDM2 regulatory axis, conferring resistance to various chemotherapeutics. TRIB2 suppression is exerted via direct interaction with AKT a key signalling protein in cell proliferation, survival and metabolism pathways. Ectopic or intrinsic high expression of TRIB2 induces drug resistance by promoting phospho-AKT (at Ser473) via its COP1 domain. TRIB2 expression is significantly increased in tumour tissues from patients correlating with an increased phosphorylation of AKT, FOXO3a, MDM2 and an impaired therapeutic response. This culminates in an extremely poor clinical outcome. Our study reveals a novel regulatory mechanism underlying drug resistance and suggests that TRIB2 functions as a regulatory component of the PI3K network, activating AKT in cancer cells. PMID:28276427

  11. Synergistic interaction of glyceraldehydes-3-phosphate dehydrogenase and ArsJ, a novel organoarsenical efflux permease, confers arsenate resistance.

    PubMed

    Chen, Jian; Yoshinaga, Masafumi; Garbinski, Luis D; Rosen, Barry P

    2016-06-01

    Microbial biotransformations are major contributors to the arsenic biogeocycle. In parallel with transformations of inorganic arsenic, organoarsenicals pathways have recently been recognized as important components of global cycling of arsenic. The well-characterized pathway of resistance to arsenate is reduction coupled to arsenite efflux. Here, we describe a new pathway of arsenate resistance involving biosynthesis and extrusion of an unusual pentavalent organoarsenical. A number of arsenic resistance (ars) operons have two genes of unknown function that are linked in these operons. One, gapdh, encodes the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase. The other, arsJ, encodes a major facilitator superfamily (MFS) protein. The two genes were cloned from the chromosome of Pseudomonas aeruginosa. When expressed together, but not alone, in Escherichia coli, gapdh and arsJ specifically conferred resistance to arsenate and decreased accumulation of As(V). Everted membrane vesicles from cells expressing arsJ accumulated As(V) in the presence of purified GAPDH, D-glceraldehylde 3-phosphate (G3P) and NAD(+) . GAPDH forms the unstable organoarsenical 1-arseno-3-phosphoglycerate (1As3PGA). We propose that ArsJ is an efflux permease that extrudes 1As3PGA from cells, where it rapidly dissociates into As(V) and 3-phosphoglycerate (3PGA), creating a novel pathway of arsenate resistance.

  12. The A395T mutation in ERG11 gene confers fluconazole resistance in Candida tropicalis causing candidemia.

    PubMed

    Tan, Jingwen; Zhang, Jinqing; Chen, Wei; Sun, Yi; Wan, Zhe; Li, Ruoyu; Liu, Wei

    2015-04-01

    The mechanism of fluconazole resistance in Candida tropicalis is still unclear. Recently, we isolated a fluconazole-resistant strain of C. tropicalis from the blood specimen of a patient with candidemia in China. In vitro antifungal susceptibility of the isolate was determined by using CLSI M27-A3 and E-test methods. The sequence of ERG11 gene was then analyzed, and the three-dimensional model of Erg11p encoded by ERG11 gene was also investigated. The sequencing of ERG11 gene revealed the mutation of A395T in this fluconazole-resistant isolate of C. tropicalis, resulting in the Y132F substitution in Erg11p. Sequence alignment and three-dimensional model comparison of Erg11ps showed high similarity between fluconazole-susceptible isolates of C. tropicalis and Candida albicans. The comparison of the three-dimensional models of Erg11ps demonstrated that the position of the Y132F substitution in this isolate of C. tropicalis is identical to the isolate of C. albicans with fluconazole resistance resulting from Y132F substitution in Erg11p. Hence, we ascertain that the Y132F substitution of Erg11p caused by A395T mutation in ERG11 gene confers the fluconazole resistance in C. tropicalis.

  13. The SCR1 gene from Schwanniomyces occidentalis encodes a highly hydrophobic polypeptide, which confers ribosomal resistance to cycloheximide.

    PubMed

    Hoenicka, Janet; Fernández Lobato, María; Marín, Dolores; Jiménez, Antonio

    2002-06-30

    In Saccharomyces cerevisiae, the SCR1 gene from Schwanniomyces occidentalis is known to induce ribosomal resistance to cycloheximide (cyh). A 2.8 kb DNA fragment encoding this gene was sequenced. Its EMBL Accession No. is AJ419770. It disclosed a putative tRNA(Asn) (GUU) sequence located downstream of an open reading frame (ORF) of 1641 nucleotides. This ORF was shown to correspond to SCR1. It would encode a highly hydrophobic polypeptide (SCR1) with 12 transmembrane domains. SCR1 is highly similar to a variety of yeast proteins of the multidrug-resistance (MDR) family. However, SCR1 only conferred resistance to cyh but not to benomyl or methotrexate. The cyh-resistance phenotype induced by SCR1 was confirmed in several S. cerevisiae strains that expressed this gene to reside at the ribosomal level. In contrast, a beta-galacosidase-tagged SCR1 was found to be integrated in the endoplasmic reticulum (ER). It is proposed that the ribosomes of yeast cells expressing SCR1 undergo a conformational change during their interaction with the ER, which lowers their affinity for cyh-binding. If so, these findings would disclose a novel ribosomal resistance mechanism.

  14. Retroviral transfer of a murine cDNA for multidrug resistance confers pleiotropic drug resistance to cells without prior drug selection

    SciTech Connect

    Guild, B.C.; Mulligan, R.C.; Gros, P.; Housman, D.E.

    1988-03-01

    The authors have constructed a retrovirus expression vector that carries the murine mdr cDNA transcribed under the control of the human H4 histone promoter to examine the feasibility of efficiently transferring a multidrug resistance phenotype to cells without requiring drug selection. This approach will facilitate the transfer of mdr cDNA to hematopoietic progenitor cells for the study of multidrug resistance in vivo. The retrovirus vector pHmdr has been used for transmission and expression of the mdr cDNA in initially drug-sensitive NIH 3T3 fibroblasts. Selection of pHmdr infectants in the cytotoxic agents colchicine or doxorubicin gave rise to highly multidrug-resistant colonies containing a single gene copy of the vector. Moreover, in the analysis of 12 cloned unselected NIH 3T3 cell infectants, a multidrug resistance phenotype was conferred by as few as two copies of the pHmdr vector. Overexpression of the mdr cDNA in drug-selected and unselected pHmdr infectants was directly related to cell survival in three cytotoxic agents tested. These results hold significant implications for the study of multidrug resistance in vivo.

  15. Allelic exchange in Mycobacterium tuberculosis with long linear recombination substrates.

    PubMed Central

    Balasubramanian, V; Pavelka, M S; Bardarov, S S; Martin, J; Weisbrod, T R; McAdam, R A; Bloom, B R; Jacobs, W R

    1996-01-01

    Genetic studies of Mycobacterium tuberculosis have been greatly hampered by the inability to introduce specific chromosomal mutations. Whereas the ability to perform allelic exchanges has provided a useful method of gene disruption in other organisms, in the clinically important species of mycobacteria, such as M. tuberculosis and Mycobacterium bovis, similar approaches have thus far been unsuccessful. In this communication, we report the development of a shuttle mutagenesis strategy that involves the use of long linear recombination substrates to reproducibly obtain recombinants by allelic exchange in M. tuberculosis. Long linear recombination substrates, approximately 40 to 50 kb in length, were generated by constructing libraries in the excisable cosmid vector pYUB328. The cosmid vector could be readily excised from the recombinant cosmids by digestion with PacI, a restriction endonuclease for which there exist few, if any, sites in mycobacterial genomes. A cosmid containing the mycobacterial leuD gene was isolated, and a selectable marker conferring resistance to kanamycin was inserted into the leuD gene in the recombinant cosmid by interplasmid recombination in Escherichia coli. A long linear recombination substrate containing the insertionally mutated leuD gene was generated by PacI digestion. Electroporation of this recombination substrate containing the insertionally mutated leuD allele resulted in the generation of leucine auxotrophic mutants by homologous recombination in 6% of the kanamycin-resistant transformants for both the Erdman and H37Rv strains of M. tuberculosis. The ability to perform allelic exchanges provides an important approach for investigating the biology of this pathogen as well as developing new live-cell M. tuberculosis-based vaccines. PMID:8550428

  16. Overexpression of MN1 Confers Resistance to Chemotherapy, Accelerates Leukemia Onset, and Suppresses p53 and Bim Induction

    PubMed Central

    Pardee, Timothy S.

    2012-01-01

    Background The transcriptional co-activator MN1 confers a worse prognosis for patients with acute myeloid leukemia (AML) when highly expressed; however, the mechanisms involved are unknown. We sought to model the effects of high MN1 expression in AML models to explore the underlying mechanisms. Methodology/Principal Findings We used cell lines and a genetically defined mouse model of AML to examine the effects of MN1 overexpression on prognosis and response to cytarabine and doxorubicin in vitro and in vivo. Murine AML that was engineered to overexpress MN1 became more aggressive in vivo, leading to shortened survival in both treated and control groups. In vitro murine AML cells that overexpressed MN1 became resistant to treatment with cytarabine and highly resistant to doxorubicin. This resistant phenotype was also seen in vivo, where treatment with the combination of cytarabine and doxorubicin selected for cells expressing MN1. When therapy-induced DNA damage levels were assessed by γH2AX foci, no reduction was seen in MN1 expressing cells arguing against a drug efflux mechanism. Despite no reduction in DNA damage, MN1-expressing cells showed less apoptosis as assessed by annexin V and propidium iodide staining. Following treatment, p53 and BIM induction were markedly reduced in cells expressing MN1. Pharmacologic inhibition of the p53 E3 ligase MDM2 resulted in increased p53 levels and improved response to doxorubicin in vitro. Conclusions/Significance MN1 overexpression accelerates an already aggressive leukemia, confers resistance to chemotherapy, and suppresses p53 and BIM induction, resulting in decreased apoptosis. This provides a mechanistic explanation of the poor prognosis observed with high MN1 expression and suggests that therapies directed at increasing p53 function may be useful for these patients. PMID:22905229

  17. Keeping the Teacher at Arm's Length: Student Resistance in Writing Conferences in Two High School Classrooms

    ERIC Educational Resources Information Center

    Consalvo, Annamary; Maloch, Beth

    2015-01-01

    The purpose of this paper is to explore a subset of findings taken from yearlong qualitative study of writing conferences in two diversely populated, urban high school classrooms. Drawing on multiple data sources, we used case study and discourse analytic methods to follow two focal students across the year in order to examine instructional and…

  18. The durable wheat disease resistance gene Lr34 confers common rust and northern corn leaf blight resistance in maize.

    PubMed

    Sucher, Justine; Boni, Rainer; Yang, Ping; Rogowsky, Peter; Büchner, Heike; Kastner, Christine; Kumlehn, Jochen; Krattinger, Simon G; Keller, Beat

    2017-04-01

    Maize (corn) is one of the most widely grown cereal crops globally. Fungal diseases of maize cause significant economic damage by reducing maize yields and by increasing input costs for disease management. The most sustainable control of maize diseases is through the release and planting of maize cultivars with durable disease resistance. The wheat gene Lr34 provides durable and partial field resistance against multiple fungal diseases of wheat, including three wheat rust pathogens and wheat powdery mildew. Because of its unique qualities, Lr34 became a cornerstone in many wheat disease resistance programmes. The Lr34 resistance is encoded by a rare variant of an ATP-binding cassette (ABC) transporter that evolved after wheat domestication. An Lr34-like disease resistance phenotype has not been reported in other cereal species, including maize. Here, we transformed the Lr34 resistance gene into the maize hybrid Hi-II. Lr34-expressing maize plants showed increased resistance against the biotrophic fungal disease common rust and the hemi-biotrophic disease northern corn leaf blight. Furthermore, the Lr34-expressing maize plants developed a late leaf tip necrosis phenotype, without negative impact on plant growth. With this and previous reports, it could be shown that Lr34 is effective against various biotrophic and hemi-biotrophic diseases that collectively parasitize all major cereal crop species.

  19. A CLAG3 mutation in an amphipathic transmembrane domain alters malaria parasite nutrient channels and confers leupeptin resistance.

    PubMed

    Sharma, Paresh; Rayavara, Kempaiah; Ito, Daisuke; Basore, Katherine; Desai, Sanjay A

    2015-06-01

    Erythrocytes infected with malaria parasites have increased permeability to ions and nutrients, as mediated by the plasmodial surface anion channel (PSAC) and recently linked to parasite clag3 genes. Although the encoded protein is integral to the host membrane, its precise contribution to solute transport remains unclear because it lacks conventional transmembrane domains and does not have homology to ion channel proteins in other organisms. Here, we identified a probable CLAG3 transmembrane domain adjacent to a variant extracellular motif. Helical-wheel analysis revealed strict segregation of polar and hydrophobic residues to opposite faces of a predicted α-helical transmembrane domain, suggesting that the domain lines a water-filled pore. A single CLAG3 mutation (A1210T) in a leupeptin-resistant PSAC mutant falls within this transmembrane domain and may affect pore structure. Allelic-exchange transfection and site-directed mutagenesis revealed that this mutation alters solute selectivity in the channel. The A1210T mutation also reduces the blocking affinity of PSAC inhibitors that bind on opposite channel faces, consistent with global changes in channel structure. Transfected parasites carrying this mutation survived a leupeptin challenge significantly better than a transfection control did. Thus, the A1210T mutation contributes directly to both altered PSAC activity and leupeptin resistance. These findings reveal the molecular basis of a novel antimalarial drug resistance mechanism, provide a framework for determining the channel's composition and structure, and should guide the development of therapies targeting the PSAC.

  20. Mapping quantitative trait loci conferring resistance to rice black-streaked virus in maize (Zea mays L.).

    PubMed

    Luan, Junwen; Wang, Fei; Li, Yujie; Zhang, Bin; Zhang, Juren

    2012-08-01

    Maize rough dwarf disease (MRDD) is one of the most serious virus diseases of maize worldwide, and it causes great reduction of maize production. In China, the pathogen was shown to be rice black-streaked virus (RBSDV). Currently, MRDD has spread broadly and leads to significant loss in China. However, there has been little research devoted to this disease. Our aims were to identify the markers and loci underlying resistance to this virus disease. In this study, segregation populations were constructed from two maize elite lines '90110', which is highly resistant to MRDD and 'Ye478', which is highly susceptible to MRDD. The F(2) and BC(1) populations were used for bulk sergeant analysis (BSA) to identify resistance-related markers. One hundred and twenty F(7:9) RILs were used for quantitative trait loci (QTL) mapping through the experiment of multiple environments over 3 years. Natural occurrence and artificial inoculation were both used and combined to determine the phenotype of plants. Five QTL, qMRD2, qMRD6, qMRD7, qMRD8 and qMRD10 were measured in the experiments. The qMRD8 on chromosome 8 was proved to be one major QTL conferring resistance to RBSDV disease in almost all traits and environments, which explained 12.0-28.9 % of the phenotypic variance for disease severity in this present study.

  1. Nucleotide sequence and characterization of the Staphylococcus aureus norA gene, which confers resistance to quinolones.

    PubMed Central

    Yoshida, H; Bogaki, M; Nakamura, S; Ubukata, K; Konno, M

    1990-01-01

    The norA gene cloned from chromosomal DNA of quinolone-resistant Staphylococcus aureus TK2566 conferred relatively high resistance to hydrophilic quinolones such as norfloxacin, enoxacin, ofloxacin, and ciprofloxacin, but only low or no resistance at all to hydrophobic ones such as nalidixic acid, oxolinic acid, and sparfloxacin in S. aureus and Escherichia coli. The 2.7-kb DNA fragment containing the norA gene had a long open reading frame coding for 388 amino acid residues with a molecular weight of 42,265, which was consistent with the experimental value of about 49,000 obtained on DNA-directed translation. The deduced NorA polypeptide has 12 hydrophobic membrane-spanning regions and is partly homologous to tetracycline resistance protein and sugar transport proteins. The uptake of a hydrophilic quinolone, enoxacin, by S. aureus harboring a plasmid carrying the norA gene was about 50% that by the parent strain lacking the plasmid, but it increased to almost the same level as that by the latter strain with carbonyl cyanide m-chlorophenyl hydrazone. On the other hand, the uptake of a hydrophobic quinolone, sparfloxacin, was similar in the two strains. These results suggest that the NorA polypeptide may constitute a membrane-associated active efflux pump of hydrophilic quinolones. PMID:2174864

  2. Balancing drug resistance and growth rates via compensatory mutations in the Plasmodium falciparum chloroquine resistance transporter.

    PubMed

    Petersen, Ines; Gabryszewski, Stanislaw J; Johnston, Geoffrey L; Dhingra, Satish K; Ecker, Andrea; Lewis, Rebecca E; de Almeida, Mariana Justino; Straimer, Judith; Henrich, Philipp P; Palatulan, Eugene; Johnson, David J; Coburn-Flynn, Olivia; Sanchez, Cecilia; Lehane, Adele M; Lanzer, Michael; Fidock, David A

    2015-07-01

    The widespread use of chloroquine to treat Plasmodium falciparum infections has resulted in the selection and dissemination of variant haplotypes of the primary resistance determinant PfCRT. These haplotypes have encountered drug pressure and within-host competition with wild-type drug-sensitive parasites. To examine these selective forces in vitro, we genetically engineered P. falciparum to express geographically diverse PfCRT haplotypes. Variant alleles from the Philippines (PH1 and PH2, which differ solely by the C72S mutation) both conferred a moderate gain of chloroquine resistance and a reduction in growth rates in vitro. Of the two, PH2 showed higher IC50 values, contrasting with reduced growth. Furthermore, a highly mutated pfcrt allele from Cambodia (Cam734) conferred moderate chloroquine resistance and enhanced growth rates, when tested against wild-type pfcrt in co-culture competition assays. These three alleles mediated cross-resistance to amodiaquine, an antimalarial drug widely used in Africa. Each allele, along with the globally prevalent Dd2 and 7G8 alleles, rendered parasites more susceptible to lumefantrine, the partner drug used in the leading first-line artemisinin-based combination therapy. These data reveal ongoing region-specific evolution of PfCRT that impacts drug susceptibility and relative fitness in settings of mixed infections, and raise important considerations about optimal agents to treat chloroquine-resistant malaria.

  3. Overexpression of the MarA positive regulator is sufficient to confer multiple antibiotic resistance in Escherichia coli.

    PubMed Central

    Gambino, L; Gracheck, S J; Miller, P F

    1993-01-01

    A genetic approach was undertaken to identify normal bacterial genes whose products function to limit the effective concentration of antibiotics. In this approach, a multicopy plasmid library containing cloned Escherichia coli chromosomal sequences was screened for transformants that showed increased resistance to a number of unrelated antibiotics. Three such plasmids were identified, and all contained sequences originating from the mar locus. DNA sequence analysis of the minimal complementation unit revealed that the resistance phenotype was associated with the presence of the marA gene on the plasmids. The putative marA gene product is predicted to contain a helix-turn-helix DNA binding domain that is very similar to analogous domains found in three other E. coli proteins. One such similarity was to the SoxS gene product, the elevated expression of which has previously been associated with the multiple antibiotic resistance (Mar) phenotype. Constitutive expression of marA conferred antibiotic resistance even in cells carrying a deletion of the chromosomal mar locus. We have also found that transformants bearing marA plasmids show a significant reduction in ompF translation but not transcription, similar to previously described mar mutants. However, this reduction in ompF expression plays only a minor role in the resistance mechanism, suggesting that functions encoded by genes unlinked to mar must be affected by marA. These results suggest that activation of marA is the ultimate event that occurs at the mar locus during the process that results in multiple antibiotic resistance. PMID:8491710

  4. Towards Positional Isolation of Three Quantitative Trait Loci Conferring Resistance to Powdery Mildew in Two Spanish Barley Landraces

    PubMed Central

    Silvar, Cristina; Perovic, Dragan; Nussbaumer, Thomas; Spannagl, Manuel; Usadel, Björn; Casas, Ana; Igartua, Ernesto; Ordon, Frank

    2013-01-01

    Three quantitative trait loci (QTL) conferring broad spectrum resistance to powdery mildew, caused by the fungus Blumeria graminis f. sp. hordei, were previously identified on chromosomes 7HS, 7HL and 6HL in the Spanish barley landrace-derived lines SBCC097 and SBCC145. In the present work, a genome-wide putative linear gene index of barley (Genome Zipper) and the first draft of the physical, genetic and functional sequence of the barley genome were used to go one step further in the shortening and explicit demarcation on the barley genome of these regions conferring resistance to powdery mildew as well as in the identification of candidate genes. First, a comparative analysis of the target regions to the barley Genome Zippers of chromosomes 7H and 6H allowed the development of 25 new gene-based molecular markers, which slightly better delimit the QTL intervals. These new markers provided the framework for anchoring of genetic and physical maps, figuring out the outline of the barley genome at the target regions in SBCC097 and SBCC145. The outermost flanking markers of QTLs on 7HS, 7HL and 6HL defined a physical area of 4 Mb, 3.7 Mb and 3.2 Mb, respectively. In total, 21, 10 and 16 genes on 7HS, 7HL and 6HL, respectively, could be interpreted as potential candidates to explain the resistance to powdery mildew, as they encode proteins of related functions with respect to the known pathogen defense-related processes. The majority of these were annotated as belonging to the NBS-LRR class or protein kinase family. PMID:23826271

  5. Screening for streptomycin resistance conferring mutations in Mycobacterium tuberculosis isolates from Iran.

    PubMed

    Rezaei, Faranak; Haeili, Mehri; Imani Fooladi, Abbasali; Azari Garmjan, Gholam Ali; Feizabadi, Mohammad Mehdi

    2017-02-01

    Point mutations in the rpsL and rrs genes can lead to development of streptomycin (STR) resistance in Mycobacterium tuberculosis. The aims of this study were to determine the frequency of mutations in STR resistant M. tuberculosis isolates in Iran and to analyze the possible relationship between bacterial genotype and STR resistance. Twenty-three M. tuberculosis samples comprising 9 multidrug-resistant (MDR) and 14 non-MDR isolates, recovered from TB patients in four regions: Tehran (n = 14), Isfahan (n = 2), Zahedan (n = 2), and Khorasan (n = 5), were analysed. Mutational profiling was performed by sequencing of the rrs and rpsL genes and spoligotyping method was used for genotyping. Nineteen isolates were resistant to STR, among them 7 exhibited mutations in the rpsL gene and 7 had mutations in the rrs gene. The remaining 5 STR resistant as well as all susceptible isolates lacked any mutation in both genes. Beijing genotype was associated with both MDR and STR resistance in which all mutations occurred at codon 43 of the rpsL gene. There was an association between mutations in the rpsL and rrs genes and STR resistance. We also found a correlation between Beijing genotype and STR resistance.

  6. Evolution and diversity of the mechanisms endowing resistance to herbicides inhibiting acetolactate-synthase (ALS) in corn poppy (Papaver rhoeas L.).

    PubMed

    Délye, Christophe; Pernin, Fanny; Scarabel, Laura

    2011-02-01

    We investigated the diversity of mechanisms conferring resistance to herbicides inhibiting acetolactate synthase (ALS) in corn poppy (Papaver rhoeas L.) and the processes underlying the selection for resistance. Six mutant ALS alleles, Arg₁₉₇, His₁₉₇, Leu₁₉₇, Ser₁₉₇, Thr₁₉₇ and Leu₅₇₄ were identified in five Italian populations. Different alleles were found in a same population or a same plant. Comparison of individual plant phenotype (herbicide sensitivity) and genotype (amino-acid substitution(s) at codon 197) showed that all mutant ALS alleles conferred dominant resistance to the field rate of the sulfonylurea tribenuron and moderate or no resistance to the field rate of the triazolopyrimidine florasulam. Depending on the allele, dominant or partially dominant resistance to the field rate of the imidazolinone imazamox was observed. Putative non-target-site resistance mechanisms were also likely present in the populations investigated. The derived Cleaved Amplified Polymorphic Sequence assays targeting ALS codons crucial for herbicide sensitivity developed in this work will facilitate the detection of resistance due to mutant ALS alleles. Nucleotide variation around codon 197 indicated that mutant ALS alleles evolved by multiple, independent appearances. Resistance to ALS inhibitors in P. rhoeas clearly evolved by redundant evolution of a set of mutant ALS alleles and likely of non-target-site mechanisms.

  7. Immuno-physiological adaptations confer wax moth Galleria mellonella resistance to Bacillus thuringiensis

    PubMed Central

    Dubovskiy, Ivan M.; Grizanova, Ekaterina V.; Whitten, Miranda M. A.; Mukherjee, Krishnendu; Greig, Carolyn; Alikina, Tatiana; Kabilov, Marsel; Vilcinskas, Andreas; Glupov, Viktor V.; Butt, Tariq M.

    2016-01-01

    ABSTRACT Microevolutionary mechanisms of resistance to a bacterial pathogen were explored in a population of the Greater wax moth, Galleria mellonella, selected for an 8.8-fold increased resistance against the entomopathogenic bacterium Bacillus thuringiensis (Bt) compared with a non-selected (suspectible) line. Defense strategies of the resistant and susceptible insect lines were compared to uncover mechanisms underpinning resistance, and the possible cost of those survival strategies. In the uninfected state, resistant insects exhibited enhanced basal expression of genes related to regeneration and amelioration of Bt toxin activity in the midgut. In addition, these insects also exhibited elevated activity of genes linked to inflammation/stress management and immune defense in the fat body. Following oral infection with Bt, the expression of these genes was further elevated in the fat body and midgut of both lines and to a greater extent some of them in resistant line than the susceptible line. This gene expression analysis reveals a pattern of resistance mechanisms targeted to sites damaged by Bt with the insect placing greater emphasis on tissue repair as revealed by elevated expression of these genes in both the fat body and midgut epithelium. Unlike the susceptible insects, Bt infection significantly reduced the diversity and richness (abundance) of the gut microbiota in the resistant insects. These observations suggest that the resistant line not only has a more intact midgut but is secreting antimicrobial factors into the gut lumen which not only mitigate Bt activity but also affects the viability of other gut bacteria. Remarkably the resistant line employs multifactorial adaptations for resistance to Bt without any detected negative trade off since the insects exhibited higher fecundity. PMID:27029421

  8. Modified cellulose synthase gene from 'Arabidopsis thaliana' confers herbicide resistance to plants

    SciTech Connect

    Somerville, Chris R.; Scieble, Wolf

    2000-10-11

    Cellulose synthase ('CS'), a key enzyme in the biosynthesis of cellulose in plants is inhibited by herbicides comprising thiazolidinones such as 5-tert-butyl-carbamoyloxy-3-(3-trifluromethyl) phenyl-4-thiazolidinone (TZ), isoxaben and 2,6-dichlorobenzonitrile (DCB). Two mutant genes encoding isoxaben and TZ-resistant cellulose synthase have been isolated from isoxaben and TZ-resistant Arabidopsis thaliana mutants. When compared with the gene coding for isoxaben or TZ-sensitive cellulose synthase, one of the resistant CS genes contains a point mutation, wherein glycine residue 998 is replaced by an aspartic acid. The other resistant mutation is due to a threonine to isoleucine change at amino acid residue 942. The mutant CS gene can be used to impart herbicide resistance to a plant; thereby permitting the utilization of the herbicide as a single application at a concentration which ensures the complete or substantially complete killing of weeds, while leaving the transgenic crop plant essentially undamaged.

  9. Modified cellulose synthase gene from Arabidopsis thaliana confers herbicide resistance to plants

    DOEpatents

    Somerville, Chris R.; Scheible, Wolf

    2007-07-10

    Cellulose synthase ("CS"), a key enzyme in the biosynthesis of cellulose in plants is inhibited by herbicides comprising thiazolidinones such as 5-tert-butyl-carbamoyloxy-3-(3-trifluromethyl)phenyl-4-thiazolidinone (TZ), isoxaben and 2,6-dichlorobenzonitrile (DCB). Two mutant genes encoding isoxaben and TZ-resistant cellulose synthase have been isolated from isoxaben and TZ-resistant Arabidopsis thaliana mutants. When compared with the gene coding for isoxaben or TZ-sensitive cellulose synthase, one of the resistant CS genes contains a point mutation, wherein glycine residue 998 is replaced by an aspartic acid. The other resistant mutation is due to a threonine to isoleucine change at amino acid residue 942. The mutant CS gene can be used to impart herbicide resistance to a plant; thereby permitting the utilization of the herbicide as a single application at a concentration which ensures the complete or substantially complete killing of weeds, while leaving the transgenic crop plant essentially undamaged.

  10. High incidence of ace-1 duplicated haplotypes in resistant Culex pipiens mosquitoes from Algeria.

    PubMed

    Alout, Haoues; Labbé, Pierrick; Pasteur, Nicole; Weill, Mylène

    2011-01-01

    The status of genes conferring resistance to organophosphate and carbamate insecticides has been examined in Culex pipiens pipiens mosquitoes sampled in Algeria. Presence of overproduced esterases was sporadic, but acetylcholinesterase-1 resistant alleles were observed in almost all samples. We focused our study on the AChE1 G119S substitution characterized in almost all samples, mostly at the heterozygous state. A genetic test revealed the presence of ace-1 duplication associating a susceptible and a resistant ace-1 copy. Molecular characterization showed a high occurrence of ace-1 duplication with six distinct duplicated alleles out of four samples. The inferred frequency of duplicated allele suggests that it is replacing the single resistant G119S allele. Finally, we discuss the mechanism at the origin of these duplicated haplotypes and their consequences on the management of insecticide resistance.

  11. Resistance to hypoxia-induced necroptosis is conferred by glycolytic pyruvate scavenging of mitochondrial superoxide in colorectal cancer cells

    PubMed Central

    Huang, C-Y; Kuo, W-T; Huang, Y-C; Lee, T-C; Yu, L C H

    2013-01-01

    Cancer cells may survive under oxygen and nutrient deprivation by metabolic reprogramming for high levels of anaerobic glycolysis, which contributes to tumor growth and drug resistance. Abnormally expressed glucose transporters (GLUTs) are colocalized with hypoxia (Hx) inducible factor (HIF)1α in peri-necrotic regions in human colorectal carcinoma. However, the underlying mechanisms of anti-necrotic resistance conferred by glucose metabolism in hypoxic cancer cells remain poorly understood. Our aim was to investigate signaling pathways of Hx-induced necroptosis and explore the role of glucose pyruvate metabolite in mechanisms of death resistance. Human colorectal carcinoma cells were Hx exposed with or without glucose, and cell necroptosis was examined by receptor-interacting protein (RIP)1/3 kinase immunoprecipitation and 32P kinase assays. Our results showed increased RIP1/3 complex formation and phosphorylation in hypoxic, but not normoxic cells in glucose-free media. Blocking RIP1 signaling, by necrostatin-1 or gene silencing, decreased lactodehydrogenase (LDH) leakage and plasma membrane disintegration. Generation of mitochondrial superoxide was noted after hypoxic challenge; its reduction by antioxidants inhibited RIP signaling and cell necrosis. Supplementation of glucose diminished the RIP-dependent LDH leakage and morphological damage in hypoxic cells, whereas non-metabolizable sugar analogs did not. Hypoxic cells given glucose showed nuclear translocation of HIF1α associated with upregulation of GLUT-1 and GLUT-4 expression, as well as increase of intracellular ATP, pyruvate and lactate levels. The glucose-mediated death resistance was ablated by iodoacetate (an inhibitor to glyceraldehyde-3-phosphate dehydrogenase), but not by UK5099 (an inhibitor to mitochondrial pyruvate carrier), suggesting that glycolytic pathway was involved in anti-necrotic mechanism. Lastly, replacing glucose with cell-permeable pyruvate derivative also led to decrease of Hx

  12. The miR9863 family regulates distinct Mla alleles in barley to attenuate NLR receptor-triggered disease resistance and cell-death signaling

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Barley Mla alleles encode coiled-coil (CC), nucleotide binding and leucine-rich repeat (NB-LRR) intracellular receptors that trigger isolate-specific immune responses against the powdery mildew fungus, Blumeria graminis f. sp. hordei (Bgh). How Mla or NB-LRR genes in grass species are regulated at p...

  13. Pathogen-induced expression of a cecropin A-melittin antimicrobial peptide gene confers antifungal resistance in transgenic tobacco.

    PubMed

    Yevtushenko, Dmytro P; Romero, Rafael; Forward, Benjamin S; Hancock, Robert E; Kay, William W; Misra, Santosh

    2005-06-01

    Expression of defensive genes from a promoter that is specifically activated in response to pathogen invasion is highly desirable for engineering disease-resistant plants. A plant transformation vector was constructed with transcriptional fusion between the pathogen-responsive win3.12T promoter from poplar and the gene encoding the novel cecropin A-melittin hybrid peptide (CEMA) with strong antimicrobial activity. This promoter-transgene combination was evaluated in transgenic tobacco (Nicotiana tabacum L. cv. Xanthi) for enhanced plant resistance against a highly virulent pathogenic fungus Fusarium solani. Transgene expression in leaves was strongly increased after fungal infection or mechanical wounding, and the accumulation of CEMA transcripts was found to be systemic and positively correlated with the number of transgene insertions. A simple and efficient in vitro regeneration bioassay for preliminary screening of transgenic lines against pathogenic fungi was developed. CEMA had strong antifungal activity in vitro, inhibiting conidia germination at concentrations that were non-toxic to tobacco protoplasts. Most importantly, the expression level of the CEMA peptide in vivo, regulated by the win3.12T promoter, was sufficient to confer resistance against F. solani in transgenic tobacco. The antifungal resistance of plants with high CEMA expression was strong and reproducible. In addition, leaf tissue extracts from transgenic plants significantly reduced the number of fungal colonies arising from germinated conidia. Accumulation of CEMA peptide in transgenic tobacco had no deleterious effect on plant growth and development. This is the first report showing the application of a heterologous pathogen-inducible promoter to direct the expression of an antimicrobial peptide in plants, and the feasibility of this approach to provide disease resistance in tobacco and, possibly, other crops.

  14. SU-C-303-01: Activation-Induced Cytidine Deaminase Confers Cancer Resistance to Radiation Therapy

    SciTech Connect

    Yi, S; La Count, S; Liu, J; Bai, X; Lu, L

    2015-06-15

    Purpose: To study the role of activation-induced cytidine deaminase (AID) in malignant cell resistance to radiation therapy. Methods: We first developed several small devices that could be used to adopt radiation beams from clinical high dose rate brachy therapy (HDR) or linac-based megavoltage machines to perform pre-clinical cell and mouse experiments. Then we used these devices to deliver radiation to AID-positive and AID-silenced cancer cells or tumors formed by these cells in mice. Cells and mice bearing tumors received the same dose under the same experimental conditions. For cells, we observed the apoptosis and the cell survival rate over time. For mice bearing tumors, we measured and recorded the tumor sizes every other day for 4 weeks. Results: For cell experiments, we found that the AID-positive cells underwent much less apoptosis compared with AID-silenced cells upon radiation. And for mouse experiments, we found that AID-positive tumors grew significantly faster than the AID-silenced tumors despite of receiving the same doses of radiation. Conclusion: Our study suggests that AID may confer cancer resistance to radiation therapy, and AID may be a significant biomarker predicting cancer resistance to radiation therapy for certain cancer types.

  15. Impairment of O-antigen production confers resistance to grazing in a model amoeba-cyanobacterium predator-prey system.

    PubMed

    Simkovsky, Ryan; Daniels, Emy F; Tang, Karen; Huynh, Stacey C; Golden, Susan S; Brahamsha, Bianca

    2012-10-09

    The grazing activity of predators on photosynthetic organisms is a major mechanism of mortality and population restructuring in natural environments. Grazing is also one of the primary difficulties in growing cyanobacteria and other microalgae in large, open ponds for the production of biofuels, as contaminants destroy valuable biomass and prevent stable, continuous production of biofuel crops. To address this problem, we have isolated a heterolobosean amoeba, HGG1, that grazes upon unicellular and filamentous freshwater cyanobacterial species. We have established a model predator-prey system using this amoeba and Synechococcus elongatus PCC 7942. Application of amoebae to a library of mutants of S. elongatus led to the identification of a grazer-resistant knockout mutant of the wzm ABC O-antigen transporter gene, SynPCC7942_1126. Mutations in three other genes involved in O-antigen synthesis and transport also prevented the expression of O-antigen and conferred resistance to HGG1. Complementation of these rough mutants returned O-antigen expression and susceptibility to amoebae. Rough mutants are easily identifiable by appearance, are capable of autoflocculation, and do not display growth defects under standard laboratory growth conditions, all of which are desired traits for a biofuel production strain. Thus, preventing the production of O-antigen is a pathway for producing resistance to grazing by certain amoebae.

  16. The L1014F point mutation in the house fly Vssc1 sodium channel confers knockdown resistance to pyrethroids.

    PubMed

    Smith, T J; Lee, S H; Ingles, P J; Knipple, D C; Soderlund, D M

    1997-10-01

    Voltage-sensitive sodium channels encoded by a full-length cDNA corresponding to the Vssc1 gene of the house fly (Musca domestica) were expressed in Xenopus laevis oocytes either alone or in combination with the tipE gene product of Drosophila melanogaster and were characterized by two-electrode voltage clamp. Vssc1 cRNA alone produced very small (50-150 nA) sodium currents, whereas the combination of Vssc1 and tipE cRNAs produced robust (0.5-3 microA), rapidly inactivating sodium currents. The pyrethroid insecticide cismethrin prolonged the sodium current carried by Vssc1/tipE sodium channels during a depolarizing pulse and induced a tail current after repolarization. The Vssc1 cDNA was specifically mutated to substitute phenylalanine for leucine at position 1014 of the inferred amino acid sequence (L1014F), a polymorphism shown previously to be associated with the kdr (knockdown resistance) trait of the house fly. The L1014F substitution reduced the sensitivity of expressed house fly sodium channels to cismethrin at least 10-fold and increased the rate of decay of pyrethroid-induced sodium tail currents. These results demonstrate that the resistance-associated L1014F mutation confers a reduction in the sensitivity of house fly sodium channels to pyrethroids that is sufficient to account for the kdr resistance trait.

  17. Viral-inducible Argonaute18 confers broad-spectrum virus resistance in rice by sequestering a host microRNA

    PubMed Central

    Wu, Jianguo; Yang, Zhirui; Wang, Yu; Zheng, Lijia; Ye, Ruiqiang; Ji, Yinghua; Zhao, Shanshan; Ji, Shaoyi; Liu, Ruofei; Xu, Le; Zheng, Hong; Zhou, Yijun; Zhang, Xin; Cao, Xiaofeng; Xie, Lianhui; Wu, Zujian; Qi, Yijun; Li, Yi

    2015-01-01

    Viral pathogens are a major threat to rice production worldwide. Although RNA interference (RNAi) is known to mediate antiviral immunity in plant and animal models, the mechanism of antiviral RNAi in rice and other economically important crops is poorly understood. Here, we report that rice resistance to evolutionarily diverse viruses requires Argonaute18 (AGO18). Genetic studies reveal that the antiviral function of AGO18 depends on its activity to sequester microRNA168 (miR168) to alleviate repression of rice AGO1 essential for antiviral RNAi. Expression of miR168-resistant AGO1a in ago18 background rescues or increases rice antiviral activity. Notably, stable transgenic expression of AGO18 confers broad-spectrum virus resistance in rice. Our findings uncover a novel cooperative antiviral activity of two distinct AGO proteins and suggest a new strategy for the control of viral diseases in rice. DOI: http://dx.doi.org/10.7554/eLife.05733.001 PMID:25688565

  18. Overproduction of superoxide dismutase and catalase confers cassava resistance to Tetranychus cinnabarinus

    PubMed Central

    Lu, Fuping; Liang, Xiao; Lu, Hui; Li, Qian; Chen, Qing; Zhang, Peng; Li, kaimian; Liu, Guanghua; Yan, Wei; Song, Jiming; Duan, Chunfang; Zhang, Linhui

    2017-01-01

    To explore the role of protective enzymes in cassava (Manihot esculenta Crantz) resistance to mites, transgenic cassava lines overproducing copper/zinc superoxide dismutase (MeCu/ZnSOD) and catalase (MeCAT1) were used to evaluate and molecularly confirm cassava resistance to Tetranychus cinnabarinus. Laboratory evaluation demonstrated that, compared with the control cultivar TMS60444 (wild type, WT), the survival, reproduction, development and activities of SOD and CAT in T. cinnabarinus feeding on transgenic cassava lines SC2, SC4, and SC11 significantly inhibited. Furthermore, the activities of SOD and CAT in transgenic cassava lines SC2, SC4, and SC11 damaged by T. cinnabarinus significantly increased. These findings were similar to the results in the mite-resistant cassava cultivars. Besides, field evaluation indicated that the transgenic cassava lines SC2, SC4, and SC11 were slightly damaged as the highly mite-resistant control C1115, while the highly mite-susceptible WT was severely damaged by T. cinnabarinus. Laboratory and field evaluation demonstrated that transgenic cassava lines were resistant to T. cinnabarinus, which directly confirmed that the increase in SOD and CAT activities was positively related to cassava resistance to T. cinnabarinus. These results will help in understanding the antioxidant defense responses in the cassava–mite interaction and molecular breeding of mite-resistant cassava for effective pest control. PMID:28054665

  19. Stacking of antimicrobial genes in potato transgenic plants confers increased resistance to bacterial and fungal pathogens.

    PubMed

    Rivero, Mercedes; Furman, Nicolás; Mencacci, Nicolás; Picca, Pablo; Toum, Laila; Lentz, Ezequiel; Bravo-Almonacid, Fernando; Mentaberry, Alejandro

    2012-01-20

    Solanum tuberosum plants were transformed with three genetic constructions expressing the Nicotiana tabacum AP24 osmotine, Phyllomedusa sauvagii dermaseptin and Gallus gallus lysozyme, and with a double-transgene construction expressing the AP24 and lysozyme sequences. Re-transformation of dermaseptin-transformed plants with the AP24/lysozyme construction allowed selection of plants simultaneously expressing the three transgenes. Potato lines expressing individual transgenes or double- and triple-transgene combinations were assayed for resistance to Erwinia carotovora using whole-plant and tuber infection assays. Resistance levels for both infection tests compared consistently for most potato lines and allowed selection of highly resistant phenotypes. Higher resistance levels were found in lines carrying the dermaseptin and lysozyme sequences, indicating that theses proteins are the major contributors to antibacterial activity. Similar results were obtained in tuber infection tests conducted with Streptomyces scabies. Plant lines showing the higher resistance to bacterial infections were challenged with Phytophthora infestans, Rhizoctonia solani and Fusarium solani. Considerable levels of resistance to each of these pathogens were evidenced employing semi-quantitative tests based in detached-leaf inoculation, fungal growth inhibition and in vitro plant inoculation. On the basis of these results, we propose that stacking of these transgenes is a promising approach to achieve resistance to both bacterial and fungal pathogens.

  20. Serine/threonine kinase gene Stpk-V, a key member of powdery mildew resistance gene Pm21, confers powdery mildew resistance in wheat.

    PubMed

    Cao, Aizhong; Xing, Liping; Wang, Xiaoyun; Yang, Xueming; Wang, Wei; Sun, Yulei; Qian, Chen; Ni, Jinlong; Chen, Yaping; Liu, Dajun; Wang, Xiue; Chen, Peidu

    2011-05-10

    Powdery mildew resistance gene Pm21, located on the chromosome 6V short arm of Haynaldia villosa and transferred to wheat as a 6VS·6AL translocation (T6VS·6AL), confers durable and broad-spectrum resistance to wheat powdery mildew. Pm21 has become a key gene resource for powdery mildew resistance breeding all over the world. In China, 12 wheat varieties containing Pm21 have been planted on more than 3.4 million hectares since 2002. Pm21 has been intractable to molecular genetic mapping because the 6VS does not pair and recombine with the 6AS. Moreover, all known accessions of H. villosa are immune to powdery mildew fungus. Pm21 is still defined by cytogenetics as a locus. In the present study, a putative serine and threonine protein kinase gene Stpk-V was cloned and characterized with an integrative strategy of molecular and cytogenetic techniques. Stpk-V is located on the Pm21 locus. The results of a single cell transient expression assay showed that Stpk-V could decrease the haustorium index dramatically. After the Stpk-V was transformed into a susceptible wheat variety Yangmai158, the characterized transgenic plants showed high and broad-spectrum powdery mildew resistance similar to T6VS·6AL. Silencing of the Stpk-V by virus-induced gene silencing in both T6VS·6AL and H. villosa resulted in their increased susceptibility. Stpk-V could be induced by Bgt and exogenous H(2)O(2), but it also mediated the increase of endogenous H(2)O(2), leading to cell death and plant resistance when the plant was attacked by Bgt.

  1. Ryanodine receptor point mutations confer diamide insecticide resistance in tomato leafminer, Tuta absoluta (Lepidoptera: Gelechiidae).

    PubMed

    Roditakis, Emmanouil; Steinbach, Denise; Moritz, Gerald; Vasakis, Emmanouil; Stavrakaki, Marianna; Ilias, Aris; García-Vidal, Lidia; Martínez-Aguirre, María Del Rosario; Bielza, Pablo; Morou, Evangelia; Silva, Jefferson E; Silva, Wellington M; Siqueira, Ηerbert A A; Iqbal, Sofia; Troczka, Bartlomiej J; Williamson, Martin S; Bass, Chris; Tsagkarakou, Anastasia; Vontas, John; Nauen, Ralf

    2017-01-01

    Insect ryanodine receptors (RyR) are the molecular target-site for the recently introduced diamide insecticides. Diamides are particularly active on Lepidoptera pests, including tomato leafminer, Tuta absoluta (Lepidoptera: Gelechiidae). High levels of diamide resistance were recently described in some European populations of T. absoluta, however, the mechanisms of resistance remained unknown. In this study the molecular basis of diamide resistance was investigated in a diamide resistant strain from Italy (IT-GELA-SD4), and additional resistant field populations collected in Greece, Spain and Brazil. The genetics of resistance was investigated by reciprocally crossing strain IT-GELA-SD4 with a susceptible strain and revealed an autosomal incompletely recessive mode of inheritance. To investigate the possible role of target-site mutations as known from diamondback moth (Plutella xylostella), we sequenced respective domains of the RyR gene of T. absoluta. Genotyping of individuals of IT-GELA-SD4 and field-collected strains showing different levels of diamide resistance revealed the presence of G4903E and I4746M RyR target-site mutations. These amino acid substitutions correspond to those recently described for diamide resistant diamondback moth, i.e. G4946E and I4790M. We also detected two novel mutations, G4903V and I4746T, in some of the resistant T. absoluta strains. Radioligand binding studies with thoracic membrane preparations of the IT-GELA-SD4 strain provided functional evidence that these mutations alter the affinity of the RyR to diamides. In combination with previous work on P. xylostella our study highlights the importance of position G4903 (G4946 in P. xylostella) of the insect RyR in defining sensitivity to diamides. The discovery of diamide resistance mutations in T. absoluta populations of diverse geographic origin has serious implications for the efficacy of diamides under applied conditions. The implementation of appropriate resistance

  2. Vat, an Amazing Gene Conferring Resistance to Aphids and Viruses They Carry: From Molecular Structure to Field Effects

    PubMed Central

    Boissot, Nathalie; Schoeny, Alexandra; Vanlerberghe-Masutti, Flavie

    2016-01-01

    We review half a century of research on Cucumis melo resistance to Aphis gossypii from molecular to field levels. The Vat gene is unique in conferring resistance to both A. gossypii and the viruses it transmits. This double phenotype is aphid clone-dependent and has been observed in 25 melon accessions, mostly from Asia. It is controlled by a cluster of genes including CC-NLR, which has been characterized in detail. Copy-number polymorphisms (for the whole gene and for a domain that stands out in the LLR region) and single-nucleotide polymorphisms have been identified in the Vat cluster. The role of these polymorphisms in plant/aphid interactions remains unclear. The Vat gene structure suggests a functioning with separate recognition and response phases. During the recognition phase, the VAT protein is thought to interact (likely indirectly) with an aphid effector introduced during cell puncture by the aphid. A few hours later, several miRNAs are upregulated in Vat plants. Peroxidase activity increases, and callose and lignin are deposited in the walls of the cells adjacent to the stylet path, disturbing aphid behavior. In aphids feeding on Vat plants, Piwi-interacting RNA-like sequences are abundant and the levels of other miRNAs are modified. At the plant level, resistance to aphids is quantitative (aphids escape the plant and display low rates of reproduction). Resistance to viruses is qualitative and local. Durability of NLR genes is highly variable. A. gossypii clones are adapted to Vat resistance, either by introducing a new effector that interferes with the deployment of plant defenses, or by adapting to the defenses it triggered. Viruses transmitted in a non-persistent manner cannot adapt to Vat resistance. At population level, Vat reduces aphid density and genetic diversity. The durability of Vat resistance to A. gossypii populations depends strongly on the agro-ecosystem, including, in particular, the presence of other cucurbit crops serving as

  3. Additive effects of two quantitative trait loci that confer Rhopalosiphum maidis (corn leaf aphid) resistance in maize inbred line Mo17

    PubMed Central

    Betsiashvili, Mariam; Ahern, Kevin R.; Jander, Georg

    2015-01-01

    Plants show considerable within-species variation in their resistance to insect herbivores. In the case of Zea mays (cultivated maize), Rhopalosiphum maidis (corn leaf aphids) produce approximately twenty times more progeny on inbred line B73 than on inbred line Mo17. Genetic mapping of this difference in maize aphid resistance identified quantitative trait loci (QTL) on chromosomes 4 and 6, with the Mo17 allele reducing aphid reproduction in each case. The chromosome 4 QTL mapping interval includes several genes involved in the biosynthesis of DIMBOA (2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one), a maize defensive metabolite that also is required for callose accumulation in response to aphid feeding. Consistent with the known association of callose with plant defence against aphids, R. maidis reproduction on B73×Mo17 recombinant inbred lines was negatively correlated with both DIMBOA content and callose formation. Further genetic mapping, as well as experiments with near-isogenic lines, confirmed that the Mo17 allele causes increased DIMBOA accumulation relative to the B73 allele. The chromosome 6 aphid resistance QTL functions independently of DIMBOA accumulation and has an effect that is additive to that of the chromosome 4 QTL. Thus, at least two separate defence mechanisms account for the higher level of R. maidis resistance in Mo17 compared with B73. PMID:25249072

  4. Structure and function of efflux pumps that confer resistance to drugs.

    PubMed Central

    Borges-Walmsley, M Ines; McKeegan, Kenneth S; Walmsley, Adrian R

    2003-01-01

    Resistance to therapeutic drugs encompasses a diverse range of biological systems, which all have a human impact. From the relative simplicity of bacterial cells, fungi and protozoa to the complexity of human cancer cells, resistance has become problematic. Stated in its simplest terms, drug resistance decreases the chance of providing successful treatment against a plethora of diseases. Worryingly, it is a problem that is increasing, and consequently there is a pressing need to develop new and effective classes of drugs. This has provided a powerful stimulus in promoting research on drug resistance and, ultimately, it is hoped that this research will provide novel approaches that will allow the deliberate circumvention of well understood resistance mechanisms. A major mechanism of resistance in both microbes and cancer cells is the membrane protein-catalysed extrusion of drugs from the cell. Resistant cells exploit proton-driven antiporters and/or ATP-driven ABC (ATP-binding cassette) transporters to extrude cytotoxic drugs that usually enter the cell by passive diffusion. Although some of these drug efflux pumps transport specific substrates, many are transporters of multiple substrates. These multidrug pumps can often transport a variety of structurally unrelated hydrophobic compounds, ranging from dyes to lipids. If we are to nullify the effects of efflux-mediated drug resistance, we must first of all understand how these efflux pumps can accommodate a diverse range of compounds and, secondly, how conformational changes in these proteins are coupled to substrate translocation. These are key questions that must be addressed. In this review we report on the advances that have been made in understanding the structure and function of drug efflux pumps. PMID:13678421

  5. Splice form variant and amino acid changes in MDR49 confers DDT resistance in transgenic Drosophila

    PubMed Central

    Seong, Keon Mook; Sun, Weilin; Clark, John M.; Pittendrigh, Barry R.

    2016-01-01

    The ATP-binding cassette (ABC) transporters represent a superfamily of proteins that have important physiological roles in both prokaryotes and eukaryotes. In insects, ABC transporters have previously been implicated in insecticide resistance. The 91-R strain of Drosophila melanogaster has been intensely selected with DDT over six decades. A recent selective sweeps analysis of 91-R implicated the potential role of MDR49, an ABC transporter, in DDT resistance, however, to date the details of how MDR49 may play a role in resistance have not been elucidated. In this study, we investigated the impact of structural changes and an alternative splicing event in MDR49 on DDT-resistance in 91-R, as compared to the DDT susceptible strain 91-C. We observed three amino acid differences in MDR49 when 91-R was compared with 91-C, and only one isoform (MDR49B) was implicated in DDT resistance. A transgenic Drosophila strain containing the 91-R-MDR49B isoform had a significantly higher LD50 value as compared to the 91-C-MDR49B isoform at the early time points (6 h to 12 h) during DDT exposure. Our data support the hypothesis that the MDR49B isoform, with three amino acid mutations, plays a role in the early aspects of DDT resistance in 91-R. PMID:27003579

  6. Splice form variant and amino acid changes in MDR49 confers DDT resistance in transgenic Drosophila.

    PubMed

    Seong, Keon Mook; Sun, Weilin; Clark, John M; Pittendrigh, Barry R

    2016-03-22

    The ATP-binding cassette (ABC) transporters represent a superfamily of proteins that have important physiological roles in both prokaryotes and eukaryotes. In insects, ABC transporters have previously been implicated in insecticide resistance. The 91-R strain of Drosophila melanogaster has been intensely selected with DDT over six decades. A recent selective sweeps analysis of 91-R implicated the potential role of MDR49, an ABC transporter, in DDT resistance, however, to date the details of how MDR49 may play a role in resistance have not been elucidated. In this study, we investigated the impact of structural changes and an alternative splicing event in MDR49 on DDT-resistance in 91-R, as compared to the DDT susceptible strain 91-C. We observed three amino acid differences in MDR49 when 91-R was compared with 91-C, and only one isoform (MDR49B) was implicated in DDT resistance. A transgenic Drosophila strain containing the 91-R-MDR49B isoform had a significantly higher LD50 value as compared to the 91-C-MDR49B isoform at the early time points (6 h to 12 h) during DDT exposure. Our data support the hypothesis that the MDR49B isoform, with three amino acid mutations, plays a role in the early aspects of DDT resistance in 91-R.

  7. Continuous treatment with FTS confers resistance to apoptosis and affects autophagy

    PubMed Central

    Schmukler, Eran; Wolfson, Eya; Elazar, Zvulun; Kloog, Yoel; Pinkas-Kramarski, Ronit

    2017-01-01

    High percentage of human cancers involves alteration or mutation in Ras proteins, including the most aggressive malignancies, such as lung, colon and pancreatic cancers. FTS (Salirasib) is a farnesylcysteine mimetic, which acts as a functional Ras inhibitor, and was shown to exert anti-tumorigenic effects in vitro and in vivo. Previously, we have demonstrated that short-term treatment with FTS also induces protective autophagy in several cancer cell lines. Drug resistance is frequently observed in cancer cells exposed to prolonged treatment, and is considered a major cause for therapy inefficiency. Therefore, in the present study, we examined the effect of a prolonged treatment with FTS on drug resistance of HCT-116 human colon cancer cells, and the involvement of autophagy in this process. We found that cells grown in the presence of FTS for 6 months have become resistant to FTS-induced cell growth inhibition and cell death. Furthermore, we discovered that the resistant cells exhibit altered autophagy, reduced apoptosis and changes in Ras-related signaling pathways following treatment with FTS. Moreover we found that while FTS induces an apoptosis-related cleavage of p62, the FTS-resistant cells were more resistant to apoptosis and p62 cleavage. PMID:28151959

  8. Candidate gene analysis and identification of TRAP and SSR markers linked to the Or5 gene, which confers sunflower resistance to race E of broomrape (Orobanche cumana Wallr.)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sunflower broomrape (Orobanche cumana Wallr.) is a root holoparasitic angiosperm considered as being one of the major constraints for sunflower production in Mediterranean areas. Breeding for resistance has been crucial for protecting sunflowers from broomrape damage. The Or5 gene, which confers re...

  9. Determination of the primary target of a quinolone drug and the effect of quinolone resistance-conferring mutations by measuring quinolone sensitivity based on its mode of action.

    PubMed

    Pfeiffer, Emily S; Hiasa, Hiroshi

    2007-09-01

    We used an assay to measure quinolone sensitivity as a shift in the position of the cleavage-religation equilibrium. This assay was found to be useful in identifying the primary target of a quinolone drug and assessing the effect of quinolone resistance-conferring mutations.

  10. The Gastrodia anti-fungal protein confers increased resistance to Phytophthora root rot and the root-knot nematode in a fruit tree species

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Gastrodia Anti-Fungal Protein (GAFP) is a monocot mannose-binding lectin isolated from the Asiatic orchid Gastrodia elata. This protein, among others, enables the orchid to live parasitically off the basidiomycete pathogen Armillaria mellea. GAFP has been shown to confer resistance to transgenic...

  11. The Geobacillus stearothermophilus V iscS Gene, Encoding Cysteine Desulfurase, Confers Resistance to Potassium Tellurite in Escherichia coli K-12

    PubMed Central

    Tantaleán, Juan C.; Araya, Manuel A.; Saavedra, Claudia P.; Fuentes, Derie E.; Pérez, José M.; Calderón, Iván L.; Youderian, Philip; Vásquez, Claudio C.

    2003-01-01

    Many eubacteria are resistant to the toxic oxidizing agent potassium tellurite, and tellurite resistance involves diverse biochemical mechanisms. Expression of the iscS gene from Geobacillus stearothermophilus V, which is naturally resistant to tellurite, confers tellurite resistance in Escherichia coli K-12, which is naturally sensitive to tellurite. The G. stearothermophilus iscS gene encodes a cysteine desulfurase. A site-directed mutation in iscS that prevents binding of its pyridoxal phosphate cofactor abolishes both enzyme activity and its ability to confer tellurite resistance in E. coli. Expression of the G. stearothermophilus iscS gene confers tellurite resistance in tellurite-hypersensitive E. coli iscS and sodA sodB mutants (deficient in superoxide dismutase) and complements the auxotrophic requirement of an E. coli iscS mutant for thiamine but not for nicotinic acid. These and other results support the hypothesis that the reduction of tellurite generates superoxide anions and that the primary targets of superoxide damage in E. coli are enzymes with iron-sulfur clusters. PMID:13129955

  12. Ovine MHC class II DRB1 alleles associated with resistance or susceptibility to development of bovine leukemia virus-induced ovine lymphoma.

    PubMed

    Nagaoka, Y; Kabeya, H; Onuma, M; Kasai, N; Okada, K; Aida, Y

    1999-02-15

    For the further characterization of bovine leukemia virus (BLV)-induced leukemogenesis, we investigated the association between polymorphism of ovine leukocyte antigen (OLA)-DRB1 gene and tumor development after infection of sheep with BLV. We infected 28 sheep with BLV and cloned exon 2 of the OLA-DRB1 gene from asymptomatic animals and from animals with lymphoma Sequence analysis revealed that, among 12 healthy sheep without any evidence of tumor, ten (83.3%) carried DRB1 alleles encoding Arg-Lys (RK) at positions beta70/71 as compared with only 6 (37.5%) of the 16 sheep with lymphoma, which suggested that alleles encoding the RK motif might protect against development of tumors after infection by BLV. By contrast, alleles encoding Ser-Arg (SR) at positions beta70/71 were present at a significantly elevated frequency in sheep with lymphoma as compared with the healthy carriers, which indicated that OLA-DRB1 alleles encoding the SR motif might be positively related to susceptibility to tumor development. The two amino acids in these motifs line a pocket that accommodates the side chain of a bound peptide according to a model of the crystal structure of human leukocyte antigen (HLA)-DR1. To analyze immunoreactions of sheep with alleles that encoded RK or SR at beta70/71, we selected sheep with either the RK/SR genotypes or the SR/SR genotypes and immunized them with a mixture of multiple synthetic antigenic peptides that corresponded to T-helper, T-cytotoxic, and B-cell epitopes of the BLV envelope glycoprotein gp51. Two weeks after the last immunization, all of the sheep were challenged with BLV. Sheep with the RK/SR genotype produced neutralizing antibodies against BLV; they eliminated BLV completely within 28 weeks of the BLV challenge, and they gave strong lymphocyte-proliferative responses to the peptides used for immunization. Moreover, such animals did not develop lymphoma. By contrast, sheep with the SR/SR genotype continued to produce BLV throughout the

  13. A Virus-Derived Stacked RNAi Construct Confers Robust Resistance to Cassava Brown Streak Disease.

    PubMed

    Beyene, Getu; Chauhan, Raj Deepika; Ilyas, Muhammad; Wagaba, Henry; Fauquet, Claude M; Miano, Douglas; Alicai, Titus; Taylor, Nigel J

    2016-01-01

    Cassava brown streak disease (CBSD) threatens food and economic security for smallholder farmers throughout East and Central Africa, and poses a threat to cassava production in West Africa. CBSD is caused by two whitefly-transmitted virus species: Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV) (Genus: Ipomovirus, Family Potyviridae). Although varying levels of tolerance have been achieved through conventional breeding, to date, effective resistance to CBSD within East African cassava germplasm has not been identified. RNAi technology was utilized to integrate CBSD resistance into the Ugandan farmer-preferred cassava cultivar TME 204. Transgenic plant lines were generated expressing an inverted repeat construct (p5001) derived from coat-protein (CP) sequences of CBSV and UCBSV fused in tandem. Northern blots using probes specific for each CP sequence were performed to characterize 169 independent transgenic lines for accumulation of CP-derived siRNAs. Transgenic plant lines accumulating low, medium and high levels of siRNAs were bud graft challenged with the virulent CBSV Naliendele isolate alone or in combination with UCBSV. Resistance to CBSD in the greenhouse directly correlated to levels of CP-derived siRNAs as determined by visual assessment of leaf and storage root symptoms, and RT-PCR diagnosis for presence of the pathogens. Low expressing lines were found to be susceptible to CBSV and UCBSV, while medium to high accumulating plant lines were resistant to both virus species. Absence of detectable virus in the best performing p5001 transgenic lines was further confirmed by back-inoculation via sap or graft challenge to CBSD susceptible Nicotiana benthamiana and cassava cultivar 60444, respectively. Data presented shows robust resistance of transgenic p5001 TME 204 lines to both CBSV and UCBSV under greenhouse conditions. Levels of resistance correlated directly with levels of transgene derived siRNA expression such that the

  14. A Virus-Derived Stacked RNAi Construct Confers Robust Resistance to Cassava Brown Streak Disease

    PubMed Central

    Beyene, Getu; Chauhan, Raj Deepika; Ilyas, Muhammad; Wagaba, Henry; Fauquet, Claude M.; Miano, Douglas; Alicai, Titus; Taylor, Nigel J.

    2017-01-01

    Cassava brown streak disease (CBSD) threatens food and economic security for smallholder farmers throughout East and Central Africa, and poses a threat to cassava production in West Africa. CBSD is caused by two whitefly-transmitted virus species: Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV) (Genus: Ipomovirus, Family Potyviridae). Although varying levels of tolerance have been achieved through conventional breeding, to date, effective resistance to CBSD within East African cassava germplasm has not been identified. RNAi technology was utilized to integrate CBSD resistance into the Ugandan farmer-preferred cassava cultivar TME 204. Transgenic plant lines were generated expressing an inverted repeat construct (p5001) derived from coat-protein (CP) sequences of CBSV and UCBSV fused in tandem. Northern blots using probes specific for each CP sequence were performed to characterize 169 independent transgenic lines for accumulation of CP-derived siRNAs. Transgenic plant lines accumulating low, medium and high levels of siRNAs were bud graft challenged with the virulent CBSV Naliendele isolate alone or in combination with UCBSV. Resistance to CBSD in the greenhouse directly correlated to levels of CP-derived siRNAs as determined by visual assessment of leaf and storage root symptoms, and RT-PCR diagnosis for presence of the pathogens. Low expressing lines were found to be susceptible to CBSV and UCBSV, while medium to high accumulating plant lines were resistant to both virus species. Absence of detectable virus in the best performing p5001 transgenic lines was further confirmed by back-inoculation via sap or graft challenge to CBSD susceptible Nicotiana benthamiana and cassava cultivar 60444, respectively. Data presented shows robust resistance of transgenic p5001 TME 204 lines to both CBSV and UCBSV under greenhouse conditions. Levels of resistance correlated directly with levels of transgene derived siRNA expression such that the

  15. Role and regulation of sigma S in general resistance conferred by low-shear simulated microgravity in Escherichia coli.

    PubMed

    Lynch, S V; Brodie, E L; Matin, A

    2004-12-01

    Life on Earth evolved in the presence of gravity, and thus it is of interest from the perspective of space exploration to determine if diminished gravity affects biological processes. Cultivation of Escherichia coli under low-shear simulated microgravity (SMG) conditions resulted in enhanced stress resistance in both exponential- and stationary-phase cells, making the latter superresistant. Given that microgravity of space and SMG also compromise human immune response, this phenomenon constitutes a potential threat to astronauts. As low-shear environments are encountered by pathogens on Earth as well, SMG-conferred resistance is also relevant to controlling infectious disease on this planet. The SMG effect resembles the general stress response on Earth, which makes bacteria resistant to multiple stresses; this response is sigma s dependent, irrespective of the growth phase. However, SMG-induced increased resistance was dependent on sigma s only in stationary phase, being independent of this sigma factor in exponential phase. sigma s concentration was some 30% lower in exponential-phase SMG cells than in normal gravity cells but was twofold higher in stationary-phase SMG cells. While SMG affected sigma s synthesis at all levels of control, the main reasons for the differential effect of this gravity condition on sigma s levels were that it rendered the sigma protein less stable in exponential phase and increased rpoS mRNA translational efficiency. Since sigma s regulatory processes are influenced by mRNA and protein-folding patterns, the data suggest that SMG may affect these configurations.

  16. Microenvironment mediated alterations to metabolic pathways confer increased chemo-resistance in CD133+ tumor initiating cells

    PubMed Central

    Nomura, Alice; Dauer, Patricia; Gupta, Vineet; McGinn, Olivia; Arora, Nivedita; Majumdar, Kaustav; III, Charles Uhlrich; Dalluge, Joseph; Dudeja, Vikas; Saluja, Ashok; Banerjee, Sulagna

    2016-01-01

    Chemoresistance in pancreatic cancer has been attributed to tumor-initiating cells (TICs), a minor sub-population of tumor cells. However, the mechanism of chemo-resistance in these cells is still unclear. In the current study, immunohistochemical analysis of LSL-KrasG12D; LSL-Trp53R172H; PdxCre (KPC) murine tumors indicated that hypoxic regions developed through tumor progression. This hypoxic “niche” correlated with increased CD133+ population that had an increased HIF1A activity. Consistent with this observation, CD133+ cells had increased glucose uptake and activity of glycolytic pathway enzymes compared to CD133− cells. Mass spectrometric analysis (UPLC-TQD) following metabolic labeling of CD133+ cells with [13C]-U6 glucose confirmed this observation. Furthermore, although both populations had functionally active mitochondria, CD133+ cells had low mitochondrial complex I and complex IV activity and lesser accumulation of ROS in response to standard chemotherapeutic compounds like paclitaxel, 5FU and gemcitabine. CD133+ cells also showed increased resistance to all three chemotherapeutic compounds and treatment with Glut1 inhibitor (STF31) reversed this resistance, promoting apoptotic death in these cells similar to CD133− cells. Our study indicates that the altered metabolic profile of CD133+ pancreatic TIC protects them against apoptosis, by reducing accumulation of ROS induced by standard chemotherapeutic agents, thereby confering chemoresistance. Since resistance to existing chemotherapy contributes to the poor prognosis in pancreatic cancer, our study paves the way for identifying novel therapeutic targets for managing chemoresistance and tumor recurrence in pancreatic cancer. PMID:27472388

  17. A Eubacterial Gene Conferring Spectinomycin Resistance on Chlamydomonas Reinhardtii: Integration into the Nuclear Genome and Gene Expression

    PubMed Central

    Cerutti, H.; Johnson, A. M.; Gillham, N. W.; Boynton, J. E.

    1997-01-01

    We have constructed a dominant selectable marker for nuclear transformation of C. reinhardtii, composed of the coding sequence of the eubacterial aadA gene (conferring spectinomycin resistance) fused to the 5' and 3' untranslated regions of the endogenous RbcS2 gene. Spectinomycin-resistant transformants isolated by direct selection (1) contain the chimeric gene(s) stably integrated into the nuclear genome, (2) show cosegregation of the resistance phenotype with the introduced DNA, and (3) synthesize the expected mRNA and protein. Small linearized plasmids appeared to be inserted into the nuclear genome preferentially through their ends, with relatively few large deletions and/or rearrangements. Multiple copy transformants often integrated concatemers of transforming DNA. Our detailed analysis of the complex integration patterns of plasmid DNA in C. reinhardtii nuclear transformants should be useful for improving the technique of insertional mutagenesis. We also found that the spectinomycin-resistance phenotype was unstable in about half of the transformants. When maintained under nonselective conditions, neither the aadA mRNA nor the AadA protein were detected in these subclones. Moreover, since the integrated transforming DNA was not altered or lost, expression of the RbcS2::aadA::RbcS2 gene(s) appears to be repressed. Measurements of transcriptional activity, mRNA accumulation, and mRNA stability suggest that expression of this chimeric gene(s) may also be affected by rapid RNA degradation, presumably due to defects in mRNA processing and/or nuclear export. Thus, both gene silencing and transcript instability, rather than biased codon usage, may explain the difficulties encountered in the expression of foreign genes in the nuclear genome of Chlamydomonas. PMID:9017393

  18. The Tn5 bleomycin resistance gene confers improved survival and growth advantage on Escherichia coli.

    PubMed

    Blot, M; Hauer, B; Monnet, G

    1994-03-01

    The bleomycin resistance gene (ble) of transposon Tn5 is known to decrease the death rate of Escherichia coli during stationary phase. Bleomycin is a DNA-damaging agent and bleomycin resistance is produced by improved DNA repair which also requires the host genes aidC and polA coding, respectively, for an alkylation-inducible gene product and DNA polymerase I. In the absence of the drug, this DNA repair system is believed to cause the slower death rate of bleomycin-resistant bacteria. In this study, the effect of ble and aidC genes on the viability of bacteria and their growth rate in chemostat competitions was studied. The results indicate, that bleomycin-resistant bacteria display greater fitness under these conditions. Another beneficial effect of transposon Tn5 had been previously attributed to the insertion sequence IS 50 R. We were not able to reproduce this result with IS 50 R, however, the complete transposon was beneficial under similar conditions. Moreover, we showed the Tn5 fitness effect to be aidC-dependent. The ble gene was discovered after the fitness effect of IS 50 R had been established; it has not previously been considered to mediate the beneficial effect of Tn5. This possibility is discussed based on the molecular mechanism of bleomycin resistance.

  19. Identification of ABC transporter genes conferring combined pleuromutilin-lincosamide-streptogramin A resistance in bovine methicillin-resistant Staphylococcus aureus and coagulase-negative staphylococci.

    PubMed

    Wendlandt, Sarah; Kadlec, Kristina; Feßler, Andrea T; Schwarz, Stefan

    2015-06-12

    The aim of this study was to investigate the genetic basis of combined pleuromutilin-lincosamide-streptogramin A resistance in 26 unrelated methicillin-resistant Staphylococcus aureus (MRSA) and coagulase-negative staphylococci (CoNS) from dairy cows suffering from mastitis. The 26 pleuromutilin-resistant staphylococcal isolates were screened for the presence of the genes vga(A), vga(B), vga(C), vga(E), vga(E) variant, sal(A), vmlR, cfr, lsa(A), lsa(B), lsa(C), and lsa(E) by PCR. None of the 26 isolates carried the genes vga(B), vga(C), vga(E), vga(E) variant, vmlR, cfr, lsa(A), lsa(B), or lsa(C). Two Staphylococcus haemolyticus and single Staphylococcus xylosus, Staphylococcus lentus, and Staphylococcus hominis were vga(A)-positive. Twelve S. aureus, two Staphylococcus warneri, as well as single S. lentus and S. xylosus carried the lsa(E) gene. Moreover, single S. aureus, S. haemolyticus, S. xylosus, and Staphylococcus epidermidis were positive for both genes, vga(A) and lsa(E). The sal(A) gene was found in a single Staphylococcus sciuri. All ABC transporter genes were located in the chromosomal DNA, except for a plasmid-borne vga(A) gene in the S. epidermidis isolate. The genetic environment of the lsa(E)-positive isolates was analyzed using previously described PCR assays. Except for the S. warneri and S. xylosus, all lsa(E)-positive isolates harbored a part of the previously described enterococcal multiresistance gene cluster. This is the first report of the novel lsa(E) gene in the aforementioned bovine CoNS species. This is also the first identification of the sal(A) gene in a S. sciuri from a case of bovine mastitis. Moreover, the sal(A) gene was shown to also confer pleuromutilin resistance.

  20. Transcription factor StWRKY1 regulates phenylpropanoid metabolites conferring late blight resistance in potato.

    PubMed

    Yogendra, Kalenahalli N; Kumar, Arun; Sarkar, Kobir; Li, Yunliang; Pushpa, Doddaraju; Mosa, Kareem A; Duggavathi, Raj; Kushalappa, Ajjamada C

    2015-12-01

    Quantitative resistance is polygenically controlled and durable, but the underlying molecular and biochemical mechanisms are poorly understood. Secondary cell wall thickening is a critical process in quantitative resistance, regulated by transcriptional networks. This paper provides compelling evidence on the functionality of StWRKY1 transcription factor, in a compatible interaction of potato-Phytophthora infestans, to extend our knowledge on the regulation of the metabolic pathway genes leading to strengthening the secondary cell wall. A metabolomics approach was used to identify resistance-related metabolites belonging to the phenylpropanoid pathway and their biosynthetic genes regulated by StWRKY1. The StWRKY1 gene in resistant potato was silenced to decipher its role in the regulation of phenylpropanoid pathway genes to strengthen the secondary cell wall. Sequencing of the promoter region of StWRKY1 in susceptible genotypes revealed the absence of heat shock elements (HSEs). Simultaneous induction of both the heat shock protein (sHSP17.8) and StWRKY1 following pathogen invasion enables functioning of the latter to interact with the HSE present in the resistant StWRKY1 promoter region. EMSA and luciferase transient expression assays further revealed direct binding of StWRKY1 to promoters of hydroxycinnamic acid amide (HCAA) biosynthetic genes encoding 4-coumarate:CoA ligase and tyramine hydroxycinnamoyl transferase. Silencing of the StWRKY1 gene was associated with signs of reduced late blight resistance by significantly increasing the pathogen biomass and decreasing the abundance of HCAAs. This study provides convincing evidence on the role of StWRKY1 in the regulation of downstream genes to biosynthesize HCAAs, which are deposited to reinforce secondary cell walls.

  1. Transcription factor StWRKY1 regulates phenylpropanoid metabolites conferring late blight resistance in potato

    PubMed Central

    Yogendra, Kalenahalli N.; Kumar, Arun; Sarkar, Kobir; Li, Yunliang; Pushpa, Doddaraju; Mosa, Kareem A.; Duggavathi, Raj; Kushalappa, Ajjamada C.

    2015-01-01

    Quantitative resistance is polygenically controlled and durable, but the underlying molecular and biochemical mechanisms are poorly understood. Secondary cell wall thickening is a critical process in quantitative resistance, regulated by transcriptional networks. This paper provides compelling evidence on the functionality of StWRKY1 transcription factor, in a compatible interaction of potato–Phytophthora infestans, to extend our knowledge on the regulation of the metabolic pathway genes leading to strengthening the secondary cell wall. A metabolomics approach was used to identify resistance-related metabolites belonging to the phenylpropanoid pathway and their biosynthetic genes regulated by StWRKY1. The StWRKY1 gene in resistant potato was silenced to decipher its role in the regulation of phenylpropanoid pathway genes to strengthen the secondary cell wall. Sequencing of the promoter region of StWRKY1 in susceptible genotypes revealed the absence of heat shock elements (HSEs). Simultaneous induction of both the heat shock protein (sHSP17.8) and StWRKY1 following pathogen invasion enables functioning of the latter to interact with the HSE present in the resistant StWRKY1 promoter region. EMSA and luciferase transient expression assays further revealed direct binding of StWRKY1 to promoters of hydroxycinnamic acid amide (HCAA) biosynthetic genes encoding 4-coumarate:CoA ligase and tyramine hydroxycinnamoyl transferase. Silencing of the StWRKY1 gene was associated with signs of reduced late blight resistance by significantly increasing the pathogen biomass and decreasing the abundance of HCAAs. This study provides convincing evidence on the role of StWRKY1 in the regulation of downstream genes to biosynthesize HCAAs, which are deposited to reinforce secondary cell walls. PMID:26417019

  2. Identification of the novel recessive gene pi55(t) conferring resistance to Magnaporthe oryzae.

    PubMed

    He, Xiuying; Liu, Xinqiong; Wang, Li; Wang, Ling; Lin, Fei; Cheng, Yongsheng; Chen, Zhaoming; Liao, Yaoping; Pan, Qinghua

    2012-02-01

    The elite rice cultivar Yuejingsimiao 2 (YJ2) is characterized by a high level of grain quality and yield, and resistance against Magnaporthe oryzae. YJ2 showed 100% resistance to four fungal populations collected from Guangdong, Sichuan, Liaoning, and Heilongjiang Provinces, which is a higher frequency than that shown by the well-known resistance (R) gene donor cultivars such as Sanhuangzhan 2 and 28zhan. Segregation analysis for resistance with F(2) and F(4) populations indicated the resistance of YJ2 was controlled by multiple genes that are dominant or recessive. The putative R genes of YJ2 were roughly tagged by SSR markers, located on chromosomes 2, 6, 8, and 12, in a bulked-segregant analysis using genome-wide selected SSR markers with F(4) lines that segregated into 3 resistant (R):1 susceptible (S) or 1R:3S. The recessive R gene on chromosome 8 was further mapped to an interval ≈1.9 cM/152 kb in length by linkage analysis with genomic position-ready markers in the mapping population derived from an F(4) line that segregated into 1R:3S. Given that no major R gene was mapped to this interval, the novel R gene was designated as pi55(t). Out of 26 candidate genes predicted in the region based on the reference genomic sequence of the cultivar Nipponbare, two genes that encode a leucine-rich repeat-containing protein and heavy-metal-associated domain-containing protein, respectively, were suggested as the most likely candidates for pi55(t).

  3. Environmentally co-occurring mercury resistance plasmids are genetically and phenotypically diverse and confer variable context-dependent fitness effects.

    PubMed

    Hall, James P J; Harrison, Ellie; Lilley, Andrew K; Paterson, Steve; Spiers, Andrew J; Brockhurst, Michael A

    2015-12-01

    Plasmids are important mobile elements that can facilitate genetic exchange and local adaptation within microbial communities. We compared the sequences of four co-occurring pQBR family environmental mercury resistance plasmids and measured their effects on competitive fitness of a Pseudomonas fluorescens SBW25 host, which was isolated at the same field site. Fitness effects of carriage differed between plasmids and were strongly context dependent, varying with medium, plasmid status of competitor and levels of environmental mercury. The plasmids also varied widely in their rates of conjugation and segregational loss. We found that few of the plasmid-borne accessory genes could be ascribed functions, although we identified a putative chemotaxis operon, a type IV pilus-encoding cluster and a region encoding putative arylsulfatase enzymes, which were conserved across geographically distant isolates. One plasmid, pQBR55, conferred the ability to catabolize sucrose. Transposons, including the mercury resistance Tn5042, appeared to have been acquired by different pQBR plasmids by recombination, indicating an important role for horizontal gene transfer in the recent evolution of pQBR plasmids. Our findings demonstrate extensive genetic and phenotypic diversity among co-occurring members of a plasmid community and suggest a role for environmental heterogeneity in the maintenance of plasmid diversity.

  4. Epigenetic inactivation of the putative DNA/RNA helicase SLFN11 in human cancer confers resistance to platinum drugs

    PubMed Central

    Nogales, Vanesa; Reinhold, William C.; Varma, Sudhir; Martinez-Cardus, Anna; Moutinho, Catia; Moran, Sebastian; Heyn, Holger; Sebio, Ana; Barnadas, Agusti; Pommier, Yves; Esteller, Manel

    2016-01-01

    Platinum-derived drugs such as cisplatin and carboplatin are among the most commonly used cancer chemotherapy drugs, but very few specific molecular and cellular markers predicting differential sensitivity to these agents in a given tumor type have been clearly identified. Epigenetic gene silencing is increasingly being recognized as a factor conferring distinct tumoral drug sensitivity, so we have used a comprehensive DNA methylation microarray platform to interrogate the widely characterized NCI60 panel of human cancer cell lines with respect to CpG methylation status and cisplatin/carboplatin sensitivity. Using this approach, we have found promoter CpG island hypermethylation-associated silencing of the putative DNA/RNA helicase Schlafen-11 (SLFN11) to be associated with increased resistance to platinum compounds. We have also experimentally validated these findings in vitro. In this setting, we also identified the BRCA1 interacting DHX9 RNA helicase (also known as RHA) as a protein partner for SLFN11, suggesting a mechanistic pathway for the observed chemoresistance effect. Most importantly, we have been able to extend these findings clinically, following the observation that those patients with ovarian and non-small cell lung cancer carrying SLFN11 hypermethylation had a poor response to both cisplatin and carboplatin treatments. Overall, these results identify SLFN11 epigenetic inactivation as a predictor of resistance to platinum drugs in human cancer. PMID:26625211

  5. Cyclic AMP (cAMP) confers drug resistance against DNA damaging agents via PKAIA in CML cells.

    PubMed

    Xiao, Ling-Yi; Kan, Wai-Ming

    2017-01-05

    Cyclic adenosine monophosphate (cAMP) regulates many vital functions such as metabolism, proliferation, differentiation and death. Depending on cell types and stimulators, cAMP could either promote or attenuate cell death. cAMP signal can be transduced by protein kinase A (PKA) and/or exchange protein directly activated by cAMP (EPAC). In CML cells, cAMP may suppress their proliferation and enhance their differentiation. However, the role of cAMP on DNA damaging agent toxicity and the mechanism involved has not been studied. In this study, we studied the effect of cAMP on the sensitivity of CML cells to DNA damaging agents. We observed that forskolin (FSK) and dibutyryl-cAMP (DBcAMP) decreased cisplatin and etoposide-induced cell death in K562 cells. Moreover, PKA activator prevented K562 cells from DNA damaging agent-induced cell death while EPAC activator had no effect. Furthermore, we found that the PKA subtype, PKAIA, was involved in cAMP-attenuated resistance in K562 cells. Taken together, our results suggest that increased cAMP level confers CML cells to acquire a novel mechanism against DNA damaging agent toxicity via PKAIA. Thus, PKAIA inhibitor may be helpful in overcoming the resistance to DNA damaging agents in CML cells.

  6. Genetic Variation in Plant CYP51s Confers Resistance against Voriconazole, a Novel Inhibitor of Brassinosteroid-Dependent Sterol Biosynthesis

    PubMed Central

    Rozhon, Wilfried; Husar, Sigrid; Kalaivanan, Florian; Khan, Mamoona; Idlhammer, Markus; Shumilina, Daria; Lange, Theo; Hoffmann, Thomas; Schwab, Wilfried; Fujioka, Shozo; Poppenberger, Brigitte

    2013-01-01

    Brassinosteroids (BRs) are plant steroid hormones with structural similarity to mammalian sex steroids and ecdysteroids from insects. The BRs are synthesized from sterols and are essential regulators of cell division, cell elongation and cell differentiation. In this work we show that voriconazole, an antifungal therapeutic drug used in human and veterinary medicine, severely impairs plant growth by inhibiting sterol-14α-demethylation and thereby interfering with BR production. The plant growth regulatory properties of voriconazole and related triazoles were identified in a screen for compounds with the ability to alter BR homeostasis. Voriconazole suppressed growth of the model plant Arabidopsis thaliana and of a wide range of both monocotyledonous and dicotyledonous plants. We uncover that voriconazole toxicity in plants is a result of a deficiency in BRs that stems from an inhibition of the cytochrome P450 CYP51, which catalyzes a step of BR-dependent sterol biosynthesis. Interestingly, we found that the woodland strawberry Fragaria vesca, a member of the Rosaceae, is naturally voriconazole resistant and that this resistance is conferred by the specific CYP51 variant of F. vesca. The potential of voriconazole as a novel tool for plant research is discussed. PMID:23335967

  7. Overexpression of the pathogen-inducible wheat TaWRKY45 gene confers disease resistance to multiple fungi in transgenic wheat plants.

    PubMed

    Bahrini, Insaf; Ogawa, Taiichi; Kobayashi, Fuminori; Kawahigashi, Hiroyuki; Handa, Hirokazu

    2011-12-01

    Recently we cloned and characterized the gene for the wheat transcription factor TaWRKY45 and showed that TaWRKY45 was upregulated in response to benzothiadiazole (BTH) and Fusarium head blight (FHB) and that its overexpression conferred enhanced resistance against F. graminearum. To characterize the functional role of TaWRKY45 in the disease resistance of wheat, in the present study we conducted expression analyses of TaWRKY45 with inoculations of powdery mildew and leaf rust and evaluated TaWRKY45-overexpressing wheat plants for resistance to these diseases. TaWRKY45 was upregulated in response to infections with Blumeria graminis, a causal fungus for powdery mildew, and Puccinia triticina, a causal fungus for leaf rust. Constitutive overexpression of the TaWRKY45 transgene conferred enhanced resistance against these two fungi on transgenic wheat plants grown under greenhouse conditions. However, the expression of two resistance-related genes, Pm3 and Lr34, was not induced by the inoculation with powdery mildew in TaWRKY45-overexpressing wheat plants. These results suggest that TaWRKY45 is involved in the defense responses for multiple fungal diseases in wheat but that resistance involving TaWRKY45 differs from at least Pm3 and/or Lr34-related resistance. Our present and previous studies indicate that TaWRKY45 may be potentially utilized to improve a wide range of disease resistance in wheat.

  8. Overexpression of the pathogen-inducible wheat TaWRKY45 gene confers disease resistance to multiple fungi in transgenic wheat plants

    PubMed Central

    Bahrini, Insaf; Ogawa, Taiichi; Kobayashi, Fuminori; Kawahigashi, Hiroyuki; Handa, Hirokazu

    2011-01-01

    Recently we cloned and characterized the gene for the wheat transcription factor TaWRKY45 and showed that TaWRKY45 was upregulated in response to benzothiadiazole (BTH) and Fusarium head blight (FHB) and that its overexpression conferred enhanced resistance against F. graminearum. To characterize the functional role of TaWRKY45 in the disease resistance of wheat, in the present study we conducted expression analyses of TaWRKY45 with inoculations of powdery mildew and leaf rust and evaluated TaWRKY45-overexpressing wheat plants for resistance to these diseases. TaWRKY45 was upregulated in response to infections with Blumeria graminis, a causal fungus for powdery mildew, and Puccinia triticina, a causal fungus for leaf rust. Constitutive overexpression of the TaWRKY45 transgene conferred enhanced resistance against these two fungi on transgenic wheat plants grown under greenhouse conditions. However, the expression of two resistance-related genes, Pm3 and Lr34, was not induced by the inoculation with powdery mildew in TaWRKY45-overexpressing wheat plants. These results suggest that TaWRKY45 is involved in the defense responses for multiple fungal diseases in wheat but that resistance involving TaWRKY45 differs from at least Pm3 and/or Lr34-related resistance. Our present and previous studies indicate that TaWRKY45 may be potentially utilized to improve a wide range of disease resistance in wheat. PMID:23136468

  9. Overexpression of a soybean salicylic acid methlyltransferase gene confers resistance to soybean cyst nematode

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soybean cyst nematode (Heterodera glycines Ichinohe, SCN) is the most pervasive pest of soybean [Glycine max (L.) Merr.] in the USA and worldwide. SCN reduced soybean yields worldwide by an estimated billion dollars annually. These losses remained stable with the use of resistant cultivars but over ...

  10. mTOR target NDRG1 confers MGMT-dependent resistance to alkylating chemotherapy.

    PubMed

    Weiler, Markus; Blaes, Jonas; Pusch, Stefan; Sahm, Felix; Czabanka, Marcus; Luger, Sebastian; Bunse, Lukas; Solecki, Gergely; Eichwald, Viktoria; Jugold, Manfred; Hodecker, Sibylle; Osswald, Matthias; Meisner, Christoph; Hielscher, Thomas; Rübmann, Petra; Pfenning, Philipp-Niklas; Ronellenfitsch, Michael; Kempf, Tore; Schnölzer, Martina; Abdollahi, Amir; Lang, Florian; Bendszus, Martin; von Deimling, Andreas; Winkler, Frank; Weller, Michael; Vajkoczy, Peter; Platten, Michael; Wick, Wolfgang

    2014-01-07

    A hypoxic microenvironment induces resistance to alkylating agents by activating targets in the mammalian target of rapamycin (mTOR) pathway. The molecular mechanisms involved in this mTOR-mediated hypoxia-induced chemoresistance, however, are unclear. Here we identify the mTOR target N-myc downstream regulated gene 1 (NDRG1) as a key determinant of resistance toward alkylating chemotherapy, driven by hypoxia but also by therapeutic measures such as irradiation, corticosteroids, and chronic exposure to alkylating agents via distinct molecular routes involving hypoxia-inducible factor (HIF)-1alpha, p53, and the mTOR complex 2 (mTORC2)/serum glucocorticoid-induced protein kinase 1 (SGK1) pathway. Resistance toward alkylating chemotherapy but not radiotherapy was dependent on NDRG1 expression and activity. In posttreatment tumor tissue of patients with malignant gliomas, NDRG1 was induced and predictive of poor response to alkylating chemotherapy. On a molecular level, NDRG1 bound and stabilized methyltransferases, chiefly O(6)-methylguanine-DNA methyltransferase (MGMT), a key enzyme for resistance to alkylating agents in glioblastoma patients. In patients with glioblastoma, MGMT promoter methylation in tumor tissue was not more predictive for response to alkylating chemotherapy in patients who received concomitant corticosteroids.

  11. Novel plasmid conferring kanamycin and tetracycline resistance in turkey-derived Campylobacter jejuni strain 11601MD

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In Campylobacter spp., resistance to the antibiotics kanamycin and tetracycline is frequently associated with plasmid-borne genes. However, relatively few plasmids of Campylobacter jejuni have been fully characterized to date. A novel plasmid (p11601MD; 44,095 bp.) harboring tet(O) was identified in...

  12. An insensitive acetylcholinesterase confers resistance to methomyl in the beet armyworm Spodoptera exigua (Lepidoptera: Noctuidae).

    PubMed

    Byrne, F J; Toscano, N C

    2001-04-01

    Two forms of acetylcholinesterase were identified in field populations of the beet armyworm, Spodoptera exigua (Hübner), collected from cotton in San Joaquin Valley, CA. Strains (BESS and BKRR) homogeneous for each variant were isolated and their relative susceptibilities to methomyl, chlorpyrifos, and chlorpyrifos-oxon assessed by topical application bioassay. In comparisons with a laboratory susceptible strain (DOW), BKRR and BESS expressed 68-fold and sevenfold resistance, respectively, to the carbamate methomyl. Neither strain was cross-resistant to chlorpyrifos or its oxygen analog (chlorpyrifos-oxon). In biochemical studies, the BKRR AChE enzyme was approximately 30-fold and sixfold more insensitive to methomyl and chlorpyrifos-oxon, respectively, compared with the DOW enzyme. The correlation between the toxicological and biochemical studies provides strong evidence that target-site insensitivity is an important mechanism of resistance to methomyl. The lack of significant cross-resistance to chlorpyrifos suggests that the insensitive AChE in these field populations was selected by methomyl alone and not by the organophosphate.

  13. Ectopic accumulation of linalool confers resistance to Xanthomonas citri subsp. citri in transgenic sweet orange plants.

    PubMed

    Shimada, Takehiko; Endo, Tomoko; Rodríguez, Ana; Fujii, Hiroshi; Goto, Shingo; Matsuura, Takakazu; Hojo, Yuko; Ikeda, Yoko; Mori, Izumi C; Fujikawa, Takashi; Peña, Leandro; Omura, Mitsuo

    2017-01-27

    In order to clarify whether high linalool content in citrus leaves alone induces strong field resistance to citrus canker caused by Xanthomonas citri subsp. citri (Xcc), and to assess whether this trait can be transferred to a citrus type highly sensitive to the bacterium, transgenic 'Hamlin' sweet orange (Citrus sinensis L. Osbeck) plants over-expressing a linalool synthase gene (CuSTS3-1) were generated. Transgenic lines (LIL) with the highest linalool content showed strong resistance to citrus canker when spray inoculated with the bacterium. In LIL plants inoculated by wounding (multiple-needle inoculation), the linalool level was correlated with the repression of the bacterial titer and up-regulation of defense-related genes. The exogenous application of salicylic acid, methyl jasmonate or linalool triggered responses similar to those constitutively induced in LIL plants. The linalool content in Ponkan mandarin leaves was significantly higher than that of leaves from six other representative citrus genotypes with different susceptibilities to Xcc We propose that linalool-mediated resistance might be unique to citrus tissues accumulating large amounts of volatile organic compounds in oil cells. Linalool might act not only as a direct antibacterial agent, but also as a signal molecule involved in triggering a non-host resistance response against Xcc.

  14. Characterisation of a mobilisable plasmid conferring florfenicol and chloramphenicol resistance in Actinobacillus pleuropneumoniae.

    PubMed

    Bossé, Janine T; Li, Yanwen; Atherton, Tom G; Walker, Stephanie; Williamson, Susanna M; Rogers, Jon; Chaudhuri, Roy R; Weinert, Lucy A; Holden, Matthew T G; Maskell, Duncan J; Tucker, Alexander W; Wren, Brendan W; Rycroft, Andrew N; Langford, Paul R

    2015-08-05

    The complete nucleotide sequence of a 7.7kb mobilisable plasmid (pM3446F), isolated from a florfenicol resistant isolate of Actinobacillus pleuropneumoniae, showed extended similarity to plasmids found in other members of the Pasteurellaceae containing the floR gene as well as replication and mobilisation genes. Mobilisation into other Pasteurellaceae species confirmed that this plasmid can be transferred horizontally.

  15. Fine mapping of barley locus Rps6 conferring resistance to wheat stripe rust

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is a major disease of wheat that is causing large economic losses in many wheat-growing regions of the world. Deployment of Pst resistance genes has been an effective strategy for controlling this pathogen, but many of these gen...

  16. Potentially Deceptive Health Nutrition-Related Advertising Claims: The Role of Inoculation in Conferring Resistance

    ERIC Educational Resources Information Center

    Mason, Alicia M.; Miller, Claude H.

    2016-01-01

    Objective: This study sought to examine the efficacy of inoculation message treatments to facilitate resistance to health nutrition-related (HNR) commercial food advertising claims. Design: Data were collected across three phases extending across a 5-week period conducted over two semesters at a Midwest US university. A 2 × 3 between-subjects…

  17. Powdery mildew resistant cucurbit rootstocks confer tolerance to grafted susceptible watermelon scions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cucurbit powdery mildew (PM) caused by Podosphaera xanthii can impact seedling growth and cause serious losses in greenhouse and open fields. We have developed watermelon and bottle gourd germplasm lines with high levels of resistance to PM. A PM susceptible watermelon cultivar Mickey Lee (ML) was g...

  18. Transgenic resistance confers effective field level control of bacterial spot disease in tomato.

    PubMed

    Horvath, Diana M; Stall, Robert E; Jones, Jeffrey B; Pauly, Michael H; Vallad, Gary E; Dahlbeck, Doug; Staskawicz, Brian J; Scott, John W

    2012-01-01

    We investigated whether lines of transgenic tomato (Solanum lycopersicum) expressing the Bs2 resistance gene from pepper, a close relative of tomato, demonstrate improved resistance to bacterial spot disease caused by Xanthomonas species in replicated multi-year field trials under commercial type growing conditions. We report that the presence of the Bs2 gene in the highly susceptible VF 36 background reduced disease to extremely low levels, and VF 36-Bs2 plants displayed the lowest disease severity amongst all tomato varieties tested, including commercial and breeding lines with host resistance. Yields of marketable fruit from transgenic lines were typically 2.5 times that of the non-transformed parent line, but varied between 1.5 and 11.5 fold depending on weather conditions and disease pressure. Trials were conducted without application of any copper-based bactericides, presently in wide use despite negative impacts on the environment. This is the first demonstration of effective field resistance in a transgenic genotype based on a plant R gene and provides an opportunity for control of a devastating pathogen while eliminating ineffective copper pesticides.

  19. The efficiency of RNA interference for conferring stable resistance to Plum Pox Virus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plum transformed with an intron hairpin RNA CP (ihRNA-CP) were resistant to PPV infection through the specific process of RNA silencing involving both small interfering -RNA interfering (siRNA) and a methylated virus transgene. This recognition process specifically targeted the triggered PPV genome...

  20. Tolerance to powdery mildew conferred in susceptible watermelon scion by grafting on resistant rootstocks

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cucurbit powdery mildew (PM) caused by Podosphaera xanthii, can impact seedling growth and cause serious losses in greenhouse and open field production. We have developed several watermelon and bottle gourd germplasm lines with high levels of resistance to PM. A PM susceptible cultivar Mickey Lee ...

  1. Identification of QTLs conferring resistance to downy mildew in legacy cultivars of lettuce

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Many cultivars of lettuce (Lactuca sativa L.), the most popular leafy vegetable, are susceptible to downy mildew disease caused by Bremia lactucae. Cultivars Iceberg and Grand Rapids that were released in 18th and 19th century, respectively, have high levels of quantitative resistance to downy milde...

  2. Identification of QTLs and possible candidate genes conferring sheath blight resistance in rice (Oryza sativa L.).

    PubMed

    Yadav, Shailesh; Anuradha, Ghanta; Kumar, Ravi Ranjan; Vemireddy, Lakshminaryana Reddy; Sudhakar, Ravuru; Donempudi, Krishnaveni; Venkata, Durgarani; Jabeen, Farzana; Narasimhan, Yamini Kalinati; Marathi, Balram; Siddiq, Ebrahimali Abubacker

    2015-01-01

    Sheath blight, caused by the pathogenic fungus Rhizoctonia solani Kühn, is one of the most devastating diseases in rice. Breeders have always faced challenges in acquiring reliable and absolute resistance to this disease in existing rice germplasm. In this context, 40 rice germplasm including eight wild, four landraces, twenty- six cultivated and two advanced breeding lines were screened utilizing the colonized bits of typha. Except Tetep and ARC10531 which expressed moderate level of resistance to the disease, none could be found to be authentically resistant. In order to map the quantitative trait loci (QTLs) governing the sheath blight resistance, two mapping populations (F2 and BC1F2) were developed from the cross BPT-5204/ARC10531. Utilizing composite interval mapping analysis, 9 QTLs mapped to five different chromosomes were identified with phenotypic variance ranging from 8.40 to 21.76%. Two SSR markers namely RM336 and RM205 were found to be closely associated with the major QTLs qshb7.3 and qshb9.2 respectively and were attested as well in BC1F2 population by bulk segregant analysis approach. A hypothetical β 1-3 glucanase with other 31 candidate genes were identified in silico utilizing rice database RAP-DB within the identified QTL region qshb9.2. A detailed insight into these candidate genes will facilitate at molecular level the intricate nature of sheath blight, a step forward towards functional genomics.

  3. Transgenic Resistance Confers Effective Field Level Control of Bacterial Spot Disease in Tomato

    PubMed Central

    Horvath, Diana M.; Stall, Robert E.; Jones, Jeffrey B.; Pauly, Michael H.; Vallad, Gary E.; Dahlbeck, Doug; Staskawicz, Brian J.; Scott, John W.

    2012-01-01

    We investigated whether lines of transgenic tomato (Solanum lycopersicum) expressing the Bs2 resistance gene from pepper, a close relative of tomato, demonstrate improved resistance to bacterial spot disease caused by Xanthomonas species in replicated multi-year field trials under commercial type growing conditions. We report that the presence of the Bs2 gene in the highly susceptible VF 36 background reduced disease to extremely low levels, and VF 36-Bs2 plants displayed the lowest disease severity amongst all tomato varieties tested, including commercial and breeding lines with host resistance. Yields of marketable fruit from transgenic lines were typically 2.5 times that of the non-transformed parent line, but varied between 1.5 and 11.5 fold depending on weather conditions and disease pressure. Trials were conducted without application of any copper-based bactericides, presently in wide use despite negative impacts on the environment. This is the first demonstration of effective field resistance in a transgenic genotype based on a plant R gene and provides an opportunity for control of a devastating pathogen while eliminating ineffective copper pesticides. PMID:22870280

  4. Salicylic acid confers enhanced resistance to Glomerella leaf spot in apple.

    PubMed

    Zhang, Ying; Shi, Xiangpeng; Li, Baohua; Zhang, Qingming; Liang, Wenxing; Wang, Caixia

    2016-09-01

    Glomerella leaf spot (GLS) caused by Glomerella cingulata is a newly emergent disease that results in severe defoliation and fruit spots in apple. Currently, there are no effective means to control this disease except for the traditional fungicide sprays. Induced resistance by elicitors against pathogens infection is a widely accepted eco-friendly strategy. In the present study, we investigated whether exogenous application of salicylic acid (SA) could improve resistance to GLS in a highly susceptible apple cultivar (Malus domestica Borkh. cv. 'Gala') and the underlying mechanisms. The results showed that pretreatment with SA, at 0.1-1.0 mM, induced strong resistance against GLS in 'Gala' apple leaves, with SA treated leaves showing significant reduction in lesion numbers and disease index. Concurrent with the enhanced disease resistance, SA treatment markedly increased the total antioxidant capacity (T-AOC) and defence-related enzyme activities, including catalase (CAT), superoxide dismutase (SOD), peroxidase (POD), phenylalanine ammonia-lyase (PAL) and polyphenol oxidase (PPO). As expected, SA treatment also induced the expression levels of five pathogenesis-related (PR) genes including PR1, PR5, PR8, Chitinase and β-1,3-glucanase. Furthermore, the most pronounced and/or rapid increase was observed in leaves treated with SA and subsequently inoculated with G. cingulata compared to the treatment with SA or inoculation with the pathogen. Together, these results suggest that exogenous SA triggered increase in reactive oxygen species levels and the antioxidant system might be responsible for enhanced resistance against G. cingulata in 'Gala' apple leaves.

  5. Novel K540N mutation in Plasmodium falciparum dihydropteroate synthetase confers a lower level of sulfa drug resistance than does a K540E mutation.

    PubMed

    Lumb, Vanshika; Sharma, Yagya D

    2011-05-01

    Sulfadoxine (SDX) and sulfamethoxazole (SMX) each inhibit the Plasmodium falciparum dihydropteroate synthetase (PfDHPS), and certain point mutations in this enzyme yield the drug-resistant parasite. Using a simple Escherichia coli model system, we describe here the effect of the recently reported novel K540N mutation in PfDHPS on the level of SDX/SMX resistance. The survival rate of the transformed E. coli (DHPS-deficient strain) under different SDX or SMX concentrations revealed that the K540N mutation confers a lower level of drug resistance than its contemporary K540E mutation. Further, SMX was more effective than SDX in the E. coli system.

  6. A cluster of four receptor-like genes resides in the Vf locus that confers resistance to apple scab disease.

    PubMed

    Xu, Mingliang; Korban, Schuyler S

    2002-12-01

    The Vf locus, derived from the crabapple species Malus floribunda 821, confers resistance to five races of the fungal pathogen Venturia inaequalis, the causal agent of apple scab disease. In our previous research, the Vf locus was restricted to a BAC contig of approximately 290 kb covered by five overlapping BAC clones. Here, we report on cloning of the resistance gene(s) present in the Vf BAC contig using a highly reliable and straightforward approach. This approach relies on hybridization of labeled cDNAs to amplified inserts of subclones derived from BAC inserts, followed by recovery of full-size transcripts by rapid amplification of cDNA ends (RACE). A cluster of four resistance paralogs (Vfa1, Vfa2, Vfa3, and Vfa4) was identified in the Vf locus. Vfa1, Vfa2 and Vfa4 had no introns and are predicted to encode proteins characterized with extracellular leucine-rich repeats (LRRs) and transmembrane (TM) domains. However, Vfa3 contains an insertion of 780 bp at the end of the LRR motif, resulting in multiple truncated transcripts. Comparison of Vfa1, Vfa2, and Vfa4 paralogs revealed a high degree of overall homology in their deduced amino acid sequences, while divergences were mainly restricted within LRR domains, including variable LRR units, numerous amino acid substitutions, and several residue deletions/duplications. Differential expression profiles among the four paralogs were observed during leaf development. Vfa1, Vfa2, and Vfa3 were active in immature leaves, but slightly expressed in mature leaves, while Vfa4 was active in immature leaves and was highly expressed in mature leaves.

  7. A cluster of four receptor-like genes resides in the Vf locus that confers resistance to apple scab disease.

    PubMed Central

    Xu, Mingliang; Korban, Schuyler S

    2002-01-01

    The Vf locus, derived from the crabapple species Malus floribunda 821, confers resistance to five races of the fungal pathogen Venturia inaequalis, the causal agent of apple scab disease. In our previous research, the Vf locus was restricted to a BAC contig of approximately 290 kb covered by five overlapping BAC clones. Here, we report on cloning of the resistance gene(s) present in the Vf BAC contig using a highly reliable and straightforward approach. This approach relies on hybridization of labeled cDNAs to amplified inserts of subclones derived from BAC inserts, followed by recovery of full-size transcripts by rapid amplification of cDNA ends (RACE). A cluster of four resistance paralogs (Vfa1, Vfa2, Vfa3, and Vfa4) was identified in the Vf locus. Vfa1, Vfa2 and Vfa4 had no introns and are predicted to encode proteins characterized with extracellular leucine-rich repeats (LRRs) and transmembrane (TM) domains. However, Vfa3 contains an insertion of 780 bp at the end of the LRR motif, resulting in multiple truncated transcripts. Comparison of Vfa1, Vfa2, and Vfa4 paralogs revealed a high degree of overall homology in their deduced amino acid sequences, while divergences were mainly restricted within LRR domains, including variable LRR units, numerous amino acid substitutions, and several residue deletions/duplications. Differential expression profiles among the four paralogs were observed during leaf development. Vfa1, Vfa2, and Vfa3 were active in immature leaves, but slightly expressed in mature leaves, while Vfa4 was active in immature leaves and was highly expressed in mature leaves. PMID:12524365

  8. Resistance mechanisms to chlorpyrifos and F392W mutation frequencies in the acetylcholine esterase ace1 allele of field populations of the tobacco whitefly, Bemisia tabaci in China.

    PubMed

    Zhang, Ning-ning; Liu, Cai-feng; Yang, Fang; Dong, Shuang-lin; Han, Zhao-jun

    2012-01-01

    The tobacco whitefly B-biotype Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) is a worldwide pest of many crops. In China, chlorpyrifos has been used to control this insect for many years and is still being used despite the fact that some resistance has been reported. To combat resistance and maintain good control efficiency of chlorpyrifos, it is essential to understand resistance mechanisms. A chlorpyrifos resistant tobacco whitefly strain (NJ-R) and a susceptible strain (NJ-S) were derived from a field-collected population in Nanjing, China, and the resistance mechanisms were investigated. More than 30-fold resistance was achieved after selected by chlorpyrifos for 13 generations in the laboratory. However, the resistance dropped significantly to about 18-fold in only 4 generations without selection pressure. Biochemical assays indicated that increased esterase activity was responsible for this resistance, while acetylcholine esterase, glutathione S-transferase, and microsomal-O-demethylase played little or no role. F392W mutations in acel were prevalent in NJ-S and NJ-R strains and 6 field-collected populations of both B and Q-biotype from locations that cover a wide geographical area of China. These findings provide important information about tobacco whitefly chlorpyrifos resistance mechanisms and guidance to combat resistance and optimize use patterns of chlorpyrifos and other organophosphate and carbamate insecticides.

  9. Resistance Mechanisms to Chlorpyrifos and F392W Mutation Frequencies in the Acetylcholine Esterase Ace1 Allele of Field Populations of the Tobacco Whitefly, Bemisia tabaci in China

    PubMed Central

    Zhang, Ning-ning; Liu, Cai-feng; Yang, Fang; Dong, Shuang-lin; Han, Zhao-jun

    2012-01-01

    The tobacco whitefly B-biotype Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) is a worldwide pest of many crops. In China, chlorpyrifos has been used to control this insect for many years and is still being used despite the fact that some resistance has been reported. To combat resistance and maintain good control efficiency of chlorpyrifos, it is essential to understand resistance mechanisms. A chlorpyrifos resistant tobacco whitefly strain (NJ-R) and a susceptible strain (NJ-S) were derived from a field-collected population in Nanjing, China, and the resistance mechanisms were investigated. More than 30-fold resistance was achieved after selected by chlorpyrifos for 13 generations in the laboratory. However, the resistance dropped significantly to about 18-fold in only 4 generations without selection pressure. Biochemical assays indicated that increased esterase activity was responsible for this resistance, while acetylcholine esterase, glutathione S-transferase, and microsomal-O-demethylase played little or no role. F392W mutations in acel were prevalent in NJ-S and NJ-R strains and 6 field-collected populations of both B and Q-biotype from locations that cover a wide geographical area of China. These findings provide important information about tobacco whitefly chlorpyrifos resistance mechanisms and guidance to combat resistance and optimize use patterns of chlorpyrifos and other organophosphate and carbamate insecticides. PMID:22954331

  10. Novel mutations conferring resistance to kanamycin in Mycobacterium tuberculosis clinical isolates from Northern India.

    PubMed

    Kaur, Simerpreet; Rana, Vibhuti; Singh, Pooja; Trivedi, Garima; Anand, Shashi; Kaur, Amanpreet; Gupta, Pawan; Jain, Amita; Sharma, Charu

    2016-01-01

    Twenty-nine Kanamycin resistant clinical isolates of Mycobacterium tuberculosis from Northern India were screened to evaluate genetic mutations in rrs gene, eis gene with its promoter, and whiB7 gene along with its 5'UTR. 14 strains (~48.0%) collectively exhibited mutations in rrs, eis or whiB7 target regions. While the highest frequency of mutations was found in rrs gene, eis and whiB7 loci displayed novel mutations. The novel mutations displayed by eis and whiB7 loci were found to be associated specifically with the Kanamycin resistance as none of the twenty nine Kanamycin sensitive strains harbor them. The inclusion of novel mutations of eis and whiB7 loci will be useful in improving the specificity of future diagnostics.

  11. BAD-Dependent Regulation of Fuel Metabolism and KATP Channel Activity Confers Resistance to Epileptic Seizures

    PubMed Central

    Giménez-Cassina, Alfredo; Martínez-François, Juan Ramón; Fisher, Jill K.; Szlyk, Benjamin; Polak, Klaudia; Wiwczar, Jessica; Tanner, Geoffrey R.; Lutas, Andrew; Yellen, Gary; Danial, Nika N.

    2012-01-01

    Summary Neuronal excitation can be substantially modulated by alterations in metabolism, as evident from the anticonvulsant effect of diets that reduce glucose utilization and promote ketone body metabolism. We provide genetic evidence that BAD, a protein with dual functions in apoptosis and glucose metabolism, imparts reciprocal effects on metabolism of glucose and ketone bodies in brain cells. These effects involve phospho-regulation of BAD and are independent of its apoptotic function. BAD modifications that reduce glucose metabolism produce a marked increase in the activity of metabolically sensitive KATP channels in neurons, as well as resistance to behavioral and electrographic seizures in vivo. Seizure resistance is reversed by genetic ablation of the KATP channel, implicating the BAD-KATP axis in metabolic control of neuronal excitation and seizure responses. PMID:22632729

  12. The pncA gene from naturally pyrazinamide-resistant Mycobacterium avium encodes pyrazinamidase and confers pyrazinamide susceptibility to resistant M. tuberculosis complex organisms.

    PubMed

    Sun, Z; Scorpio, A; Zhang, Y

    1997-10-01

    The antituberculosis drug pyrazinamide (PZA) needs to be converted into pyrazinoic acid (POA) by the bacterial pyrazinamidase (PZase) in order to show bactericidal activity against Mycobacterium tuberculosis. M. avium is naturally resistant to PZA. To investigate whether this natural resistance to PZA is due to inability of the M. avium PZase to convert PZA to bactericidal POA, the M. avium PZase gene (pncA) was cloned by using the M. tuberculosis pncA gene as a probe. Sequence analysis showed that the M. avium pncA gene is 561 bp long, encoding a protein with a predicted size of about 19.8 kDa; but Western blotting showed that the M. avium PZase migrated as a 24 kDa band when expressed in M. bovis BCG and Escherichia coli. Sequence comparison revealed that M. avium PZase has 67.7% and 32.8% amino acid identity with the corresponding enzymes from M. tuberculosis and E. coli, respectively. Southern blot analysis with the M. avium pncA gene as a probe showed that M. terrae, M. gastri, M. marinum, M. fortuitum, M. xenopi, M. gordonae, M. szulgai, M. celatum and M. kansasii have close pncA homologues, whereas M. chelonae and M. smegmatis did not give significant hybridization signals. Transformation with the M. avium pncA gene conferred PZA susceptibility to PZA-resistant M. tuberculosis complex organisms, indicating that the nonsusceptibility of M. avium to PZA is not due to an ineffective PZase enzyme, but appears to be related to other factors such as transport of POA.

  13. The pan-PI3K inhibitor GDC-0941 activates canonical WNT signaling to confer resistance in TNBC cells: resistance reversal with WNT inhibitor.

    PubMed

    Tzeng, Huey-En; Yang, Lixin; Chen, Kemin; Wang, Yafan; Liu, Yun-Ru; Pan, Shiow-Lin; Gaur, Shikha; Hu, Shuya; Yen, Yun

    2015-05-10

    The pan-PI3K inhibitors are one treatment option for triple-negative breast cancer (TNBC). However, this treatment is ineffective for unknown reasons. Here, we report that aberrant expression of wingless-type MMTV integration site family (WNT) and activated WNT signals, which crosstalk with the PI3K-AKT-mTOR signaling pathway through GSK3β, plays the most critical role in resistance to pan-PI3K inhibitors in TNBC cells. GDC-0941 is a pan-PI3K inhibitor that activates the WNT/beta-catenin pathway in TNBC cells through stimulation of WNT secretion. GDC-0941-triggered WNT/beta-catenin pathway activation was observed in MDA-MB-231 and HCC1937 cells, which are TNBC cell lines showing aberrant WNT/beta-catenin activation, and not in SKBR3 and MCF7 cells. This observation is further investigated in vivo. GDC-0941 exhibited minimal tumor inhibition in MDA-MB-231 cells, but it significantly suppressed tumor growth in HER-positive SK-BR3 cells. In vivo mechanism study revealed the activation of WNT/beta-catenin pathway by GDC-0941. A synergistic effect was observed when combined treatment with GDC-0941 and the WNT inhibitor LGK974 at low concentrations in MDA-MB-231 cells. These findings indicated that WNT pathway activation conferred resistance in TNBC cells treated with GDC-0941. This resistance may be further circumvented through combined treatment with pan-PI3K and WNT inhibitors. Future clinical trials of these two inhibitors are warranted.

  14. Allelic diversity in an NLR gene BPH9 enables rice to combat planthopper variation

    PubMed Central

    Zhao, Yan; Huang, Jin; Wang, Zhizheng; Jing, Shengli; Wang, Yang; Ouyang, Yidan; Cai, Baodong; Xin, Xiu-Fang; Liu, Xin; Zhang, Chunxiao; Pan, Yufang; Ma, Rui; Li, Qiaofeng; Jiang, Weihua; Zeng, Ya; Shangguan, Xinxin; Wang, Huiying; Du, Bo; Zhu, Lili; Xu, Xun; Feng, Yu-Qi; He, Sheng Yang; Chen, Rongzhi; Zhang, Qifa; He, Guangcun

    2016-01-01

    Brown planthopper (BPH), Nilaparvata lugens Stål, is one of the most devastating insect pests of rice (Oryza sativa L.). Currently, 30 BPH-resistance genes have been genetically defined, most of which are clustered on specific chromosome regions. Here, we describe molecular cloning and characterization of a BPH-resistance gene, BPH9, mapped on the long arm of rice chromosome 12 (12L). BPH9 encodes a rare type of nucleotide-binding and leucine-rich repeat (NLR)-containing protein that localizes to the endomembrane system and causes a cell death phenotype. BPH9 activates salicylic acid- and jasmonic acid-signaling pathways in rice plants and confers both antixenosis and antibiosis to BPH. We further demonstrated that the eight BPH-resistance genes that are clustered on chromosome 12L, including the widely used BPH1, are allelic with each other. To honor the priority in the literature, we thus designated this locus as BPH1/9. These eight genes can be classified into four allelotypes, BPH1/9-1, -2, -7, and -9. These allelotypes confer varying levels of resistance to different biotypes of BPH. The coding region of BPH1/9 shows a high level of diversity in rice germplasm. Homologous fragments of the nucleotide-binding (NB) and leucine-rich repeat (LRR) domains exist, which might have served as a repository for generating allele diversity. Our findings reveal a rice plant strategy for modifying the genetic information to gain the upper hand in the struggle against insect herbivores. Further exploration of natural allelic variation and artificial shuffling within this gene may allow breeding to be tailored to control emerging biotypes of BPH. PMID:27791169

  15. Screening for Escherichia coli K-12 genes conferring glyoxal resistance or sensitivity by transposon insertions.

    PubMed

    Lee, Changhan; Kim, Jihong; Kwon, Minsuk; Lee, Kihyun; Min, Haeyoung; Kim, Seong Hun; Kim, Dongkyu; Lee, Nayoung; Kim, Jiyeun; Kim, Doyun; Ko, Changmin; Park, Chankyu

    2016-09-01

    Glyoxal (GO) belongs to the reactive electrophilic species generated in vivo in all organisms. In order to identify targets of GO and their response mechanisms, we attempted to screen for GO-sensitive mutants by random insertions of TnphoA-132. The genes responsible for GO susceptibility were functionally classified as the following: (i) tRNA modification; trmE, gidA and truA, (ii) DNA repair; recA and recC, (iii) toxin-antitoxin; mqsA and (iv) redox metabolism; yqhD and caiC In addition, an insertion in the crp gene, encoding the cAMP responsive transcription factor, exhibits a GO-resistant phenotype, which is consistent with the phenotype of adenylate cyclase (cya) mutant showing GO resistance. This suggests that global regulation involving cAMP is operated in a stress response to GO. To further characterize the CRP-regulated genes directly associated with GO resistance, we created double mutants deficient in both crp and one of the candidate genes including yqhD, gloA and sodB The results indicate that these genes are negatively regulated by CRP as confirmed by real-time RT-PCR. We propose that tRNA as well as DNA are the targets of GO and that toxin/antitoxin, antioxidant and cAMP are involved in cellular response to GO.

  16. An additional Meyerozyma guilliermondii IMH3 gene confers mycophenolic acid resistance in fungal CTG clade species.

    PubMed

    Defosse, Tatiana A; Mélin, Céline; Clastre, Marc; Besseau, Sébastien; Lanoue, Arnaud; Glévarec, Gaëlle; Oudin, Audrey; Dugé de Bernonville, Thomas; Vandeputte, Patrick; Linder, Tomas; Bouchara, Jean-Philippe; Courdavault, Vincent; Giglioli-Guivarc'h, Nathalie; Papon, Nicolas

    2016-09-01

    The fungal CTG clade comprises a number of well-known yeasts that impact human health or with high biotechnological potential. To further extend the set of molecular tools dedicated to these microorganisms, the initial focus of this study was to develop a mycophenolic acid (MPA) resistance cassette. Surprisingly, while we were carrying out preliminary susceptibility testing experiments in a set of yeast species, Meyerozyma guilliermondii, although not being a MPA producer, was found to be primarily resistant toward this drug, whereas a series of nine related species were susceptible to MPA. Using comparative and functional genomic approaches, we demonstrated that all MPA-susceptible CTG clade species display a single gene, referred to as IMH3.1, encoding the MPA target inosine monophosphate dehydrogenase (IMPDH) and that MPA resistance relies on the presence in the M. guilliermondii genome of an additional IMPDH-encoding gene (IMH3.2). The M. guilliermondii IMH3.2 gene displays marked differences compared to IMH3.1 including the lack of intron, a roughly 160-fold higher transcription level and a serine residue at position 251. Placed under the control of the M. guilliermondii actin 1 gene promoter, IMH3.2 was successfully used to transform Lodderomyces elongisporus, Clavispora lusitaniae, Scheffersomyces stipitis and Candida parapsilosis.

  17. MIMIVIRE is a defence system in mimivirus that confers resistance to virophage.

    PubMed

    Levasseur, Anthony; Bekliz, Meriem; Chabrière, Eric; Pontarotti, Pierre; La Scola, Bernard; Raoult, Didier

    2016-03-10

    Since their discovery, giant viruses have revealed several unique features that challenge the conventional definition of a virus, such as their large and complex genomes, their infection by virophages and their presence of transferable short element transpovirons. Here we investigate the sensitivity of mimivirus to virophage infection in a collection of 59 viral strains and demonstrate lineage specificity in the resistance of mimivirus to Zamilon, a unique virophage that can infect lineages B and C of mimivirus but not lineage A. We hypothesized that mimiviruses harbour a defence mechanism resembling the clustered regularly interspaced short palindromic repeat (CRISPR)-Cas system that is widely present in bacteria and archaea. We performed de novo sequencing of 45 new mimivirus strains and searched for sequences specific to Zamilon in a total of 60 mimivirus genomes. We found that lineage A strains are resistant to Zamilon and contain the insertion of a repeated Zamilon sequence within an operon, here named the 'mimivirus virophage resistance element' (MIMIVIRE). Further analyses of the surrounding sequences showed that this locus is reminiscent of a defence mechanism related to the CRISPR-Cas system. Silencing the repeated sequence and the MIMIVIRE genes restores mimivirus susceptibility to Zamilon. The MIMIVIRE proteins possess the typical functions (nuclease and helicase) involved in the degradation of foreign nucleic acids. The viral defence system, MIMIVIRE, represents a nucleic-acid-based immunity against virophage infection.

  18. Modulation of auxin content in Arabidopsis confers improved drought stress resistance.

    PubMed

    Shi, Haitao; Chen, Li; Ye, Tiantian; Liu, Xiaodong; Ding, Kejian; Chan, Zhulong

    2014-09-01

    Auxin is a well-known plant phytohormone that is involved in multiple plant growth processes and stress responses. In this study, auxin response was significantly modulated under drought stress condition. The iaaM-OX transgenic lines with higher endogenous indole-3-acetic acid (IAA) level and IAA pre-treated wild type (WT) plants exhibited enhanced drought stress resistance, while the yuc1yuc2yuc6 triple mutants with lower endogenous IAA level showed decreased stress resistance in comparison to non-treated WT plants. Additionally, endogenous and exogenous auxin positively modulated the expression levels of multiple abiotic stress-related genes (RAB18, RD22, RD29A, RD29B, DREB2A, and DREB2B), and positively affected reactive oxygen species (ROS) metabolism and underlying antioxidant enzyme activities. Moreover, auxin significantly modulated some carbon metabolites including amino acids, organic acids, sugars, sugar alcohols and aromatic amines. Notably, endogenous and exogenous auxin positively modulated root architecture especially the lateral root number. Taken together, this study demonstrated that auxin might participate in the positive regulation of drought stress resistance, through regulation of root architecture, ABA-responsive genes expression, ROS metabolism, and metabolic homeostasis, at least partially.

  19. Expression of a chitinase gene from Metarhizium anisopliae in tobacco plants confers resistance against Rhizoctonia solani.

    PubMed

    Kern, Marcelo Fernando; Maraschin, Simone de Faria; Vom Endt, Débora; Schrank, Augusto; Vainstein, Marilene Henning; Pasquali, Giancarlo

    2010-04-01

    The chit1 gene from the entomopathogenic fungus Metarhizium anisopliae, encoding the endochitinase CHIT42, was placed under the control of the CaMV 35S promoter, and the resulting construct was transferred to tobacco. Seventeen kanamycin-resistant transgenic lines were recovered, and the presence of the transgene was confirmed by polymerase chain reactions and Southern blot hybridization. The number of chit1 copies was determined to be varying from one to four. Copy number had observable effects neither on plant growth nor development. Substantial heterogeneity concerning production of the recombinant chitinase, and both general and specific chitinolytic activities were detected in leaf extracts from primary transformants. The highest chitinase activities were found in plants harboring two copies of chit1 inserts at different loci. Progeny derived from self-pollination of the primary transgenics revealed a stable inheritance pattern, with transgene segregation following a mendelian dihybrid ratio. Two selected plants expressing high levels of CHIT42 were consistently resistant to the soilborne pathogen Rhizoctonia solani, suggesting a direct relationship between enzyme activity and reduction of foliar area affected by fungal lesions. To date, this is the first report of resistance to fungal attack in plants mediated by a recombinant chitinase from an entomopathogenic and acaricide fungus.

  20. FLCN and AMPK Confer Resistance to Hyperosmotic Stress via Remodeling of Glycogen Stores

    PubMed Central

    Possik, Elite; Ajisebutu, Andrew; Manteghi, Sanaz; Gingras, Marie-Claude; Vijayaraghavan, Tarika; Flamand, Mathieu; Coull, Barry; Schmeisser, Kathrin; Duchaine, Thomas; van Steensel, Maurice; Hall, David H.; Pause, Arnim

    2015-01-01

    Mechanisms of adaptation to environmental changes in osmolarity are fundamental for cellular and organismal survival. Here we identify a novel osmotic stress resistance pathway in Caenorhabditis elegans (C. elegans), which is dependent on the metabolic master regulator 5’-AMP-activated protein kinase (AMPK) and its negative regulator Folliculin (FLCN). FLCN-1 is the nematode ortholog of the tumor suppressor FLCN, responsible for the Birt-Hogg-Dubé (BHD) tumor syndrome. We show that flcn-1 mutants exhibit increased resistance to hyperosmotic stress via constitutive AMPK-dependent accumulation of glycogen reserves. Upon hyperosmotic stress exposure, glycogen stores are rapidly degraded, leading to a significant accumulation of the organic osmolyte glycerol through transcriptional upregulation of glycerol-3-phosphate dehydrogenase enzymes (gpdh-1 and gpdh-2). Importantly, the hyperosmotic stress resistance in flcn-1 mutant and wild-type animals is strongly suppressed by loss of AMPK, glycogen synthase, glycogen phosphorylase, or simultaneous loss of gpdh-1 and gpdh-2 enzymes. Our studies show for the first time that animals normally exhibit AMPK-dependent glycogen stores, which can be utilized for rapid adaptation to either energy stress or hyperosmotic stress. Importantly, we show that glycogen accumulates in kidneys from mice lacking FLCN and in renal tumors from a BHD patient. Our findings suggest a dual role for glycogen, acting as a reservoir for energy supply and osmolyte production, and both processes might be supporting tumorigenesis. PMID:26439621

  1. The Clostridium difficile cell wall protein CwpV confers phase-variable phage resistance.

    PubMed

    Sekulovic, Ognjen; Ospina Bedoya, Maicol; Fivian-Hughes, Amanda S; Fairweather, Neil F; Fortier, Louis-Charles

    2015-10-01

    Bacteriophages are present in virtually all ecosystems, and bacteria have developed multiple antiphage strategies to counter their attacks. Clostridium difficile is an important pathogen causing severe intestinal infections in humans and animals. Here we show that the conserved cell-surface protein CwpV provides antiphage protection in C. difficile. This protein, for which the expression is phase-variable, is classified into five types, each differing in their repeat-containing C-terminal domain. When expressed constitutively from a plasmid or the chromosome of locked 'ON' cells of C. difficile R20291, CwpV conferred antiphage protection. Differences in the level of phage protection were observed depending on the phage morphological group, siphophages being the most sensitive with efficiency of plaquing (EOP) values of < 5 × 10(-7) for phages ϕCD38-2, ϕCD111 and ϕCD146. Protection against the myophages ϕMMP01 and ϕCD52 was weaker, with EOP values between 9.0 × 10(-3) and 1.1 × 10(-1). The C-terminal domain of CwpV carries the antiphage activity and its deletion, or part of it, significantly reduced the antiphage protection. CwpV does not affect phage adsorption, but phage DNA replication is prevented, suggesting a mechanism reminiscent of superinfection exclusion systems normally encoded on prophages. CwpV thus represents a novel ubiquitous host-encoded and phase-variable antiphage system in C. difficile.

  2. The Cytochrome P450 gene CYP6P12 confers pyrethroid resistance in kdr-free Malaysian populations of the dengue vector Aedes albopictus

    PubMed Central

    Ishak, Intan H.; Riveron, Jacob M.; Ibrahim, Sulaiman S.; Stott, Rob; Longbottom, Joshua; Irving, Helen; Wondji, Charles S.

    2016-01-01

    Control of Aedes albopictus, major dengue and chikungunya vector, is threatened by growing cases of insecticide resistance. The mechanisms driving this resistance remain poorly characterised. This study investigated the molecular basis of insecticide resistance in Malaysian populations of Ae. albopictus. Microarray-based transcription profiling revealed that metabolic resistance (cytochrome P450 up-regulation) and possibly a reduced penetration mechanism (consistent over-expression of cuticular protein genes) were associated with pyrethroid resistance. CYP6P12 over-expression was strongly associated with pyrethroid resistance whereas CYP6N3 was rather consistently over-expressed across carbamate and DDT resistant populations. Other detoxification genes also up-regulated in permethrin resistant mosquitoes included a glucuronosyltransferase (AAEL014279-RA) and the glutathione-S transferases GSTS1 and GSTT3. Functional analyses further supported that CYP6P12 contributes to pyrethroid resistance in Ae. albopictus as transgenic expression of CYP6P12 in Drosophila was sufficient to confer pyrethroid resistance in these flies. Furthermore, molecular docking simulations predicted CYP6P12 possessing enzymatic activity towards pyrethroids. Patterns of polymorphism suggested early sign of selection acting on CYP6P12 but not on CYP6N3. The major role played by P450 in the absence of kdr mutations suggests that addition of the synergist PBO to pyrethroids could improve the efficacy of this insecticide class and overcome resistance in field populations of Ae. albopictus. PMID:27094778

  3. Presence of new mecA and mph(C) variants conferring antibiotic resistance in Staphylococcus spp. isolated from the skin of horses before and after clinic admission.

    PubMed

    Schnellmann, Christina; Gerber, Vinzenz; Rossano, Alexandra; Jaquier, Valentine; Panchaud, Yann; Doherr, Marcus G; Thomann, Andreas; Straub, Reto; Perreten, Vincent

    2006-12-01

    Because of the frequency of multiple antibiotic resistance, Staphylococcus species often represent a challenge in incisional infections of horses undergoing colic surgery. To investigate the evolution of antibiotic resistance patterns before and after preventative peri- and postoperative penicillin treatment, staphylococci were isolated from skin and wound samples at different times during hospitalization. Most staphylococci were normal skin commensals and belonged to the common coagulase-negative group. In some cases they turned out to be opportunistic pathogens present in wound infections. MICs were determined for 12 antibiotics, and antibiotic resistance genes were detected by microarray. At hospital admission, horses harbored staphylococci that were susceptible to antibiotics or resistant to one group of drugs, mainly due to the presence of new variants of the methicillin and macrolide resistance genes mecA and mph(C), respectively. After 3 days, the percentage of Staphylococcus isolates displaying antibiotic resistance, as well as the number of resistance genes per isolate, increased moderately in hospitalized horses without surgery or penicillin treatment but dramatically in hospitalized horses after colic surgery as well as penicillin treatment. Staphylococcus species displaying multiple resistance were found to harbor mainly genes conferring resistance to beta-lactams (mecA and blaZ), aminoglycosides [str and aac(6')-Ie-aph(2')-Ia], and trimethoprim [dfr(A) and dfr(D)]. Additional genes conferring resistance to macrolides [mph(C), erm(C), and erm(B)], tetracycline [tet(K) and tet(M)], chloramphenicol [cat(pC221) and cat(pC223)], and streptothricin (sat4) appeared in several strains. Hospitalization and preventive penicillin use were shown to act as selection agents for multidrug-resistant commensal staphylococcal flora.

  4. Nuclear PIM1 confers resistance to rapamycin-impaired endothelial proliferation.

    PubMed

    Walpen, Thomas; Kalus, Ina; Schwaller, Jürg; Peier, Martin A; Battegay, Edouard J; Humar, Rok

    2012-12-07

    The PIM serine/threonine kinases and the mTOR/AKT pathway integrate growth factor signaling and promote cell proliferation and survival. They both share phosphorylation targets and have overlapping functions, which can partially substitute for each other. In cancer cells PIM kinases have been reported to produce resistance to mTOR inhibition by rapamycin. Tumor growth depends highly on blood vessel infiltration into the malignant tissue and therefore on endothelial cell proliferation. We therefore investigated how the PIM1 kinase modulates growth inhibitory effects of rapamycin in mouse aortic endothelial cells (MAEC). We found that proliferation of MAEC lacking Pim1 was significantly more sensitive to rapamycin inhibition, compared to wildtype cells. Inhibition of mTOR and AKT in normal MAEC resulted in significantly elevated PIM1 protein levels in the cytosol and in the nucleus. We observed that truncation of the C-terminal part of Pim1 beyond Ser 276 resulted in almost exclusive nuclear localization of the protein. Re-expression of this Pim1 deletion mutant significantly increased the proliferation of Pim1(-/-) cells when compared to expression of the wildtype Pim1 cDNA. Finally, overexpression of the nuclear localization mutant and the wildtype Pim1 resulted in complete resistance to growth inhibition by rapamycin. Thus, mTOR inhibition-induced nuclear accumulation of PIM1 or expression of a nuclear C-terminal PIM1 truncation mutant is sufficient to increase endothelial cell proliferation, suggesting that nuclear localization of PIM1 is important for resistance of MAEC to rapamycin-mediated inhibition of proliferation.

  5. Human recombinant antimannan immunoglobulin G1 antibody confers resistance to hematogenously disseminated candidiasis in mice.

    PubMed

    Zhang, Mason X; Bohlman, M Charlotte; Itatani, Carol; Burton, Dennis R; Parren, Paul W H I; St Jeor, Stephen C; Kozel, Thomas R

    2006-01-01

    Mannan is a major cell wall component found in Candida species. Natural antimannan antibody is present in sera from most normal adults, but its role in host resistance to hematogenously disseminated candidiasis is unknown. The purpose of this study was to develop recombinant human antimannan antibody and to study its protective function. A phage Fab display combinatorial library containing Fab genes from bone marrow lymphocytes was screened with Candida albicans yeast cells and chemically purified mannan. One antimannan Fab, termed M1, was converted to a full-length immunoglobulin G1 antibody, M1g1, and M1g1 was produced in CHO cells. The M1g1 epitope was found in C. albicans serotypes A and B, Candida tropicalis, Candida guilliermondii, Candida glabrata, and Candida parapsilosis. Its expression was active at both 23 degrees C and 37 degrees C and uniform over the cell surface. BALB/c mice passively immunized with M1g1 were more resistant than control mice to a lethal hematogenous infection by C. albicans, as evidenced by extension of survival in an M1g1 dose-dependent manner (P, 0.08 to <0.001) and by reduction in number of infection foci and their size in the kidney. In vitro studies found that M1g1 promoted phagocytosis and phagocytic killing of C. albicans yeast cells by mouse peritoneal macrophages and was required for activation of the mouse complement cascade. Thus, human antimannan antibody may have a protective role in host resistance to systemic candidiasis.

  6. A Locus at 5q33.3 Confers Resistance to Tuberculosis in Highly Susceptible Individuals

    PubMed Central

    Sobota, Rafal S.; Stein, Catherine M.; Kodaman, Nuri; Scheinfeldt, Laura B.; Maro, Isaac; Wieland-Alter, Wendy; Igo, Robert P.; Magohe, Albert; Malone, LaShaunda L.; Chervenak, Keith; Hall, Noemi B.; Modongo, Chawangwa; Zetola, Nicola; Matee, Mecky; Joloba, Moses; Froment, Alain; Nyambo, Thomas B.; Moore, Jason H.; Scott, William K.; Lahey, Timothy; Boom, W. Henry; von Reyn, C. Fordham; Tishkoff, Sarah A.; Sirugo, Giorgio; Williams, Scott M.

    2016-01-01

    Immunosuppression resulting from HIV infection increases the risk of progression to active tuberculosis (TB) both in individuals newly exposed to Mycobacterium tuberculosis (MTB) and in those with latent infections. We hypothesized that HIV-positive individuals who do not develop TB, despite living in areas where it is hyperendemic, provide a model of natural resistance. We performed a genome-wide association study of TB resistance by using 581 HIV-positive Ugandans and Tanzanians enrolled in prospective cohort studies of TB; 267 of these individuals developed active TB, and 314 did not. A common variant, rs4921437 at 5q33.3, was significantly associated with TB (odds ratio = 0.37, p = 2.11 × 10−8). This variant lies within a genomic region that includes IL12B and is embedded in an H3K27Ac histone mark. The locus also displays consistent patterns of linkage disequilibrium across African populations and has signals of strong selection in populations from equatorial Africa. Along with prior studies demonstrating that therapy with IL-12 (the cytokine encoded in part by IL12B, associated with longer survival following MTB infection in mice deficient in CD4 T cells), our results suggest that this pathway might be an excellent target for the development of new modalities for treating TB, especially for HIV-positive individuals. Our results also indicate that studying extreme disease resistance in the face of extensive exposure can increase the power to detect associations in complex infectious disease. PMID:26942285

  7. Prototype demonstration of transgenic resistance to the nematode Radopholus similis conferred on banana by a cystatin.

    PubMed

    Atkinson, Howard J; Grimwood, Sam; Johnston, Kate; Green, Jayne

    2004-04-01

    Cavendish banana was transformed using Agrobacterium tumefaciens to express a protein engineered rice cystatin (OcIdeltaD86) of value for control of plant parasitic nematodes. Expression for each line was under control of a constitutive promoter from the maize ubiquitin gene (UBI-1), a constitutive, chimeric promoter from the octopine and mannopine synthase genes of A. tumefaciens or a promoter from a root-preferentially expressed tubulin gene Arabidopsis (TUB-1). Lines were selected as of potential interest after 8 weeks challenge in containment if their mean R. similis/25 g roots for three sibling plants were more than 1 standard normal variate below the grand mean for all plants in c7-15 lines challenged concurrently. A total of 16 lines were selected on this basis as putative positives. Western blots confirmed that eight of these lines expressed cystatin with a mean of 0.08 +/- 0.04% tsp. All but two of 19 negatively selected lines from bioassays did not express cystatin. The mean resistance level of the confirmed positive lines was 69 +/- 17%. ELISA established the positive lines under control of UBI provided significantly higher expression levels of OcIdeltaD86 than recorded for the other two promoters. Lines of interest were confirmed as producing a transcript for OcIdeltaD86 by RT-PCR. Eight plants of one UBI promoter line expressing only 0.1 +/- 0.004% tsp as cystatin were re-challenged with R. similis and achieved a resistance of 70 +/- 10%. Subsequent repeat western blotting confirmed that this line still produced the cystatin after the trial. This is the first report of transgenic resistance against a major pest or disease of banana.

  8. Mutations in Novel Lipopolysaccharide Biogenesis Genes Confer Resistance to Amoebal Grazing in Synechococcus elongatus

    PubMed Central

    Effner, Emily E.; Iglesias-Sánchez, Maria José; Golden, Susan S.

    2016-01-01

    In natural and artificial aquatic environments, population structures and dynamics of photosynthetic microbes are heavily influenced by the grazing activity of protistan predators. Understanding the molecular factors that affect predation is critical for controlling toxic cyanobacterial blooms and maintaining cyanobacterial biomass production ponds for generating biofuels and other bioproducts. We previously demonstrated that impairment of the synthesis or transport of the O-antigen component of lipopolysaccharide (LPS) enables resistance to amoebal grazing in the model predator-prey system consisting of the heterolobosean amoeba HGG1 and the cyanobacterium Synechococcus elongatus PCC 7942 (R. S. Simkovsky et al., Proc Natl Acad Sci U S A 109:16678–16683, 2012, http://dx.doi.org/10.1073/pnas.1214904109). In this study, we used this model system to identify additional gene products involved in the synthesis of O antigen, the ligation of O antigen to the lipid A-core conjugated molecule (including a novel ligase gene), the generation of GDP-fucose, and the incorporation of sugars into the lipid A core oligosaccharide of S. elongatus. Knockout of any of these genes enables resistance to HGG1, and of these, only disruption of the genes involved in synthesis or incorporation of GDP-fucose into the lipid A-core molecule impairs growth. Because these LPS synthesis genes are well conserved across the diverse range of cyanobacteria, they enable a broader understanding of the structure and synthesis of cyanobacterial LPS and represent mutational targets for generating resistance to amoebal grazers in novel biomass production strains. PMID:26921432

  9. The Entamoeba histolytica Dnmt2 homolog (Ehmeth) confers resistance to nitrosative stress.

    PubMed

    Hertz, Rivi; Tovy, Ayala; Kirschenbaum, Michael; Geffen, Meirav; Nozaki, Tomoyoshi; Adir, Noam; Ankri, Serge

    2014-04-01

    Nitric oxide (NO) has antimicrobial properties against many pathogens due to its reactivity as an S-nitrosylating agent. It inhibits many of the key enzymes that are involved in the metabolism and virulence of the parasite Entamoeba histolytica through S-nitrosylation of essential cysteine residues. Very little information is available on the mechanism of resistance to NO by pathogens in general and by this parasite in particular. Here, we report that exposure of the parasites to S-nitrosoglutathione (GSNO), an NO donor molecule, strongly reduces their viability and protein synthesis. However, the deleterious effects of NO were significantly reduced in trophozoites overexpressing Ehmeth, the cytosine-5 methyltransferase of the Dnmt2 family. Since these trophozoites also exhibited high levels of tRNA(Asp) methylation, the high levels suggested that Ehmeth-mediated tRNA(Asp) methylation is part of the resistance mechanism to NO. We previously reported that enolase, another glycolytic enzyme, binds to Ehmeth and inhibits its activity. We observed that the amount of Ehmeth-enolase complex was significantly reduced in GSNO-treated E. histolytica, which explains the aforementioned increase of tRNA methylation. Specifically, we demonstrated via site-directed mutagenesis that cysteine residues 228 and 229 of Ehmeth are susceptible to S-nitrosylation and are crucial for Ehmeth binding to enolase and for Ehmeth-mediated resistance to NO. These results indicate that Ehmeth has a central role in the response of the parasite to NO, and they contribute to the growing evidence that NO is a regulator of epigenetic mechanisms.

  10. Expression of the Galanthus nivalis agglutinin (GNA) gene in transgenic potato plants confers resistance to aphids.

    PubMed

    Mi, Xiaoxiao; Liu, Xue; Yan, Haolu; Liang, Lina; Zhou, Xiangyan; Yang, Jiangwei; Si, Huaijun; Zhang, Ning

    2017-01-01

    Aphids, the largest group of sap-sucking pests, cause significant yield losses in agricultural crops worldwide every year. The massive use of pesticides to combat this pest causes severe damage to the environment, putting in risk the human health. In this study, transgenic potato plants expressing Galanthus nivalis agglutinin (GNA) gene were developed using CaMV 35S and ST-LS1 promoters generating six transgenic lines (35S1-35S3 and ST1-ST3 corresponding to the first and second promoter, respectively). Quantitative real-time polymerase chain reaction (qRT-PCR) analysis indicated that the GNA gene was expressed in leaves, stems and roots of transgenic plants under the control of the CaMV 35S promoter, while it was only expressed in leaves and stems under the control of the ST-LS1 promoter. The levels of aphid mortality after 5 days of the inoculation in the assessed transgenic lines ranged from 20 to 53.3%. The range of the aphid population in transgenic plants 15 days after inoculation was between 17.0±1.43 (ST2) and 36.6±0.99 (35S3) aphids per plant, which corresponds to 24.9-53.5% of the aphid population in non-transformed plants. The results of our study suggest that GNA expressed in transgenic potato plants confers a potential tolerance to aphid attack, which appears to be an alternative against the use of pesticides in the future.

  11. Epithelial-to-mesenchymal transition (EMT) confers primary resistance to trastuzumab (Herceptin).

    PubMed

    Oliveras-Ferraros, Cristina; Corominas-Faja, Bruna; Cufí, Sílvia; Vazquez-Martin, Alejandro; Martin-Castillo, Begoña; Iglesias, Juan Manuel; López-Bonet, Eugeni; Martin, Ángel G; Menendez, Javier A

    2012-11-01

    The rate of inherent resistance to single-agent trastuzumab in HER2-overexpressing metastatic breast carcinomas is impressive at above 70%. Unfortunately, little is known regarding the distinctive genetic signatures that could predict trastuzumab refractoriness ab initio. The epithelial-to-mesenchymal transition (EMT) molecular features, HER2 expression status and primary responses to trastuzumab were explored in the public Lawrence Berkeley Laboratory (LBL) Breast Cancer Collection. Lentivirus-delivered small hairpin RNAs were employed to reduce specifically and stably the expression of EMT transcription factors in trastuzumab-refractory basal/HER2+ cells. Cell proliferation assays and pre-clinical nude mice xenograft-based studies were performed to assess the contribution of specific EMT transcription factors to inherent trastuzumab resistance. Primary sensitivity to trastuzumab was restricted to the SLUG/SNAIL2-negative subset of luminal/HER2+ cell lines, whereas all of the SLUG/SNAIL2-positive basal/HER2+ cell lines exhibited an inherent resistance to trastuzumab. The specific knockdown of SLUG/SNAIL2 suppressed the stem-related CD44+CD24(-/low) mesenchymal immunophenotype by transcriptionally upregulating the luminal epithelial marker CD24 in basal/HER2+ cells. Basal/HER2+ cells gained sensitivity to the growth-inhibitory effects of trastuzumab following SLUG/SNAIL2 gene depletion, which induced the expression of the mesenchymal-to-epithelial transition (MET) genes involved in promoting an epithelial phenotype. The isolation of CD44+CD24(-/low) mesenchymal cells by magnetic-activated cell sorting (MACS) confirmed their intrinsic unresponsiveness to trastuzumab. A reduction in tumor growth and dramatic gain in sensitivity to trastuzumab in vivo were confirmed when the SLUG/SNAIL2 knockdown basal/HER2+ cells were injected into nude mice. HER2 overexpression in a basal, rather than in a luminal molecular background, results in a basal/HER2+ breast cancer subtype

  12. Superoxide dismutase transgenes in sugarbeets confer resistance to oxidative agents and the fungus C. beticola.

    PubMed

    Tertivanidis, Konstantinos; Goudoula, Catherine; Vasilikiotis, Christos; Hassiotou, Efthymia; Perl-Treves, Rafael; Tsaftaris, Athanasios

    2004-06-01

    Sugarbeets carrying superoxide dismutase transgenes were developed in order to investigate the possibility of enhancing their resistance to oxidative stress. Binary T-DNA vectors carrying the chloroplastic and cytosolic superoxide dismutase genes from tomato, were used for Agrobacterium-mediated transformation of sugarbeet petioles. The transgenic plants were subjected to treatments known to cause oxidative stress, such as the herbicide methyl viologen and a natural photosensitizer toxin produced by the fungus Cercospora beticola, namely cercosporin. The transgenic plants exhibited increased tolerance to methyl viologen, to pure cercosporin, as well as to leaf infection with the fungus C. beticola.

  13. Identification of yeast genes that confer resistance to chitosan oligosaccharide (COS) using chemogenomics

    PubMed Central

    2012-01-01

    Background Chitosan oligosaccharide (COS), a deacetylated derivative of chitin, is an abundant, and renewable natural polymer. COS has higher antimicrobial properties than chitosan and is presumed to act by disrupting/permeabilizing the cell membranes of bacteria, yeast and fungi. COS is relatively non-toxic to mammals. By identifying the molecular and genetic targets of COS, we hope to gain a better understanding of the antifungal mode of action of COS. Results Three different chemogenomic fitness assays, haploinsufficiency (HIP), homozygous deletion (HOP), and multicopy suppression (MSP) profiling were combined with a transcriptomic analysis to gain insight in to the mode of action and mechanisms of resistance to chitosan oligosaccharides. The fitness assays identified 39 yeast deletion strains sensitive to COS and 21 suppressors of COS sensitivity. The genes identified are involved in processes such as RNA biology (transcription, translation and regulatory mechanisms), membrane functions (e.g. signalling, transport and targeting), membrane structural components, cell division, and proteasome processes. The transcriptomes of control wild type and 5 suppressor strains overexpressing ARL1, BCK2, ERG24, MSG5, or RBA50, were analyzed in the presence and absence of COS. Some of the up-regulated transcripts in the suppressor overexpressing strains exposed to COS included genes involved in transcription, cell cycle, stress response and the Ras signal transduction pathway. Down-regulated transcripts included those encoding protein folding components and respiratory chain proteins. The COS-induced transcriptional response is distinct from previously described environmental stress responses (i.e. thermal, salt, osmotic and oxidative stress) and pre-treatment with these well characterized environmental stressors provided little or any resistance to COS. Conclusions Overexpression of the ARL1 gene, a member of the Ras superfamily that regulates membrane trafficking, provides

  14. Antiviral activity produced by an IPNV-carrier EPC cell culture confers resistance to VHSV infection.

    PubMed

    Jurado, María Teresa; García-Valtanen, Pablo; Estepa, Amparo; Perez, Luis

    2013-10-25

    Infectious pancreatic necrosis virus (IPNV), a fish birnavirus, can establish a persistent infection on epithelioma papulosum cyprinid (EPC) cells producing a carrier state where a small fraction of IPNV-infected cells is maintained in the culture after continuous subculture. The EPC(IPNV) cells are resistant to challenge with IPNV as well as to challenge with viral hemorrhagic septicemia virus (VHSV), a rhabdovirus. In this work, the antiviral effect of the IPNV carrier culture conditioned medium (EPC(IPNV)-CM) was tested and analyzed in detail. EPC cells treated with the carrier culture supernatant become protected against VHSV challenge. Size-fractionation by filtration and acid and heat treatment showed that the IPNV persistently infected cells release an acid-resistant soluble factor in the molecular weight fraction bellow 50 kDa. The capacity of the EPC(IPNV)-CM to induce cytokine genes in EPC cells was also determined by real-time RT-PCR. We found that there is a positive correlation between up-regulation of mx gene expression in EPC cells treated with EPC(IPNV)-CM and protection against VHSV challenge. Our findings indicate that the control of IPNV multiplication in the carrier culture as well as the interference with rhabdovirus replication are connected to the production and release of an antiviral (interferon-like) factor to the medium.

  15. Glioma cell VEGFR-2 confers resistance to chemotherapeutic and antiangiogenic treatments in PTEN-deficient glioblastoma.

    PubMed

    Kessler, Tobias; Sahm, Felix; Blaes, Jonas; Osswald, Matthias; Rübmann, Petra; Milford, David; Urban, Severino; Jestaedt, Leonie; Heiland, Sabine; Bendszus, Martin; Hertenstein, Anne; Pfenning, Philipp-Niclas; Ruiz de Almodóvar, Carmen; Wick, Antje; Winkler, Frank; von Deimling, Andreas; Platten, Michael; Wick, Wolfgang; Weiler, Markus

    2015-10-13

    Loss of the tumor suppressor phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a prerequisite for tumor cell-specific expression of vascular endothelial growth factor receptor (VEGFR)-2 in glioblastoma defining a subgroup prone to develop evasive resistance towards antiangiogenic treatments. Immunohistochemical analysis of human tumor tissues showed VEGFR-2 expression in glioma cells in 19% of specimens examined, mainly in the infiltration zone. Glioma cell VEGFR-2 positivity was restricted to PTEN-deficient tumor specimens. PTEN overexpression reduced VEGFR-2 expression in vitro, as well as knock-down of raptor or rictor. Genetic interference with VEGFR-2 revealed proproliferative, antiinvasive and chemoprotective functions for VEGFR-2 in glioma cells. VEGFR-2-dependent cellular effects were concomitant with activation of 'kappa-light-chain-enhancer' of activated B-cells, protein kinase B, and N-myc downstream regulated gene 1. Two-photon in vivo microscopy revealed that expression of VEGFR-2 in glioma cells hampers antiangiogenesis. Bevacizumab induces a proinvasive response in VEGFR-2-positive glioma cells. Patients with PTEN-negative glioblastomas had a shorter survival after initiation of bevacizumab therapy compared with PTEN-positive glioblastomas. Conclusively, expression of VEGFR-2 in glioma cells indicates an aggressive glioblastoma subgroup developing early resistance to temozolomide or bevacizumab. Loss of PTEN may serve as a biomarker identifying those tumors upfront by routine neuropathological methods.

  16. Characterization of Mobile Staphylococcus equorum Plasmids Isolated from Fermented Seafood That Confer Lincomycin Resistance

    PubMed Central

    Lee, Jong-Hoon; Jeong, Do-Won

    2015-01-01

    The complete nucleotide sequences of lincomycin-resistance gene (lnuA)-containing plasmids in Staphylococcus equorum strains isolated from the high-salt-fermented seafood jeotgal were determined. These plasmids, designated pSELNU1–3, are 2638-bp long, have two polymorphic sites, and encode typical elements found in plasmids that replicate via a rolling-circle mechanism including the replication protein gene (rep), a double-stranded origin of replication, a single-stranded origin of replication, and counter-transcribed RNA sequence, as well as lnuA. Plasmid sequences exhibit over 83% identity to other Staphylococcus plasmids that harbor rep and lnuA genes. Further, three pairs of identified direct repeats may be involved in inter-plasmid recombination. One plasmid, pSELNU1, was successfully transferred to other Staphylococcus species, Enterococcus faecalis, and Tetragenococcus halophilus in vitro. Antibiotic susceptibility of the transconjugants was host-dependent, and transconjugants maintained a lincomycin resistance phenotype in the absence of selective pressure over 60 generations. PMID:26448648

  17. The association of glycolytic enzymes from yeast confers resistance against inhibition by trehalose.

    PubMed

    Araiza-Olivera, Daniela; Sampedro, José G; Mújica, Adela; Peña, Antonio; Uribe-Carvajal, Salvador

    2010-05-01

    During stress, many organisms accumulate compatible solutes. These solutes must be eliminated upon return to optimal conditions as they inhibit cell metabolism and growth. In contrast, enzyme interactions optimize metabolism through mechanisms such as channeling of substrates. It was decided to test the (compatible solute) trehalose-mediated inhibition of some yeast glycolytic pathway enzymes known to associate and whether inhibition is prevented when enzymes are allowed to associate. Trehalose inhibited the isolated glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and hexokinase (HXK), but not aldolase (ALD) nor phosphoglycerate kinase (PGK). When these enzymes were mixed in pairs, both GAPDH and HXK were protected by either ALD or PGK acquiring the inhibition behavior of the resistant enzyme. GAPDH was not protected by HXK, albumin or lactate dehydrogenase (LDH). Also, ALD did not protect glucose 6-phosphate dehydrogenase (G6PDH), suggesting that protection is specific. In yeast cell extracts, fermentation was resistant to trehalose inhibition, suggesting all enzymes involved in the glucose-dependent production of ethanol were stabilized. It is suggested that during the yeast stress response, enzyme association protects some metabolic pathways against trehalose-mediated inhibition.

  18. Nuclear PIM1 confers resistance to rapamycin-impaired endothelial proliferation

    SciTech Connect

    Walpen, Thomas; Kalus, Ina; Schwaller, Juerg; Peier, Martin A.; Battegay, Edouard J.; Humar, Rok

    2012-12-07

    Highlights: Black-Right-Pointing-Pointer Pim1{sup -/-} endothelial cell proliferation displays increased sensitivity to rapamycin. Black-Right-Pointing-Pointer mTOR inhibition by rapamycin enhances PIM1 cytosolic and nuclear protein levels. Black-Right-Pointing-Pointer Truncation of Pim1 beyond serine 276 results in nuclear localization of the kinase. Black-Right-Pointing-Pointer Nuclear PIM1 increases endothelial proliferation independent of rapamycin. -- Abstract: The PIM serine/threonine kinases and the mTOR/AKT pathway integrate growth factor signaling and promote cell proliferation and survival. They both share phosphorylation targets and have overlapping functions, which can partially substitute for each other. In cancer cells PIM kinases have been reported to produce resistance to mTOR inhibition by rapamycin. Tumor growth depends highly on blood vessel infiltration into the malignant tissue and therefore on endothelial cell proliferation. We therefore investigated how the PIM1 kinase modulates growth inhibitory effects of rapamycin in mouse aortic endothelial cells (MAEC). We found that proliferation of MAEC lacking Pim1 was significantly more sensitive to rapamycin inhibition, compared to wildtype cells. Inhibition of mTOR and AKT in normal MAEC resulted in significantly elevated PIM1 protein levels in the cytosol and in the nucleus. We observed that truncation of the C-terminal part of Pim1 beyond Ser 276 resulted in almost exclusive nuclear localization of the protein. Re-expression of this Pim1 deletion mutant significantly increased the proliferation of Pim1{sup -/-} cells when compared to expression of the wildtype Pim1 cDNA. Finally, overexpression of the nuclear localization mutant and the wildtype Pim1 resulted in complete resistance to growth inhibition by rapamycin. Thus, mTOR inhibition-induced nuclear accumulation of PIM1 or expression of a nuclear C-terminal PIM1 truncation mutant is sufficient to increase endothelial cell proliferation

  19. Estrogen receptor alpha somatic mutations Y537S and D538G confer breast cancer endocrine resistance by stabilizing the activating function-2 binding conformation

    PubMed Central

    Fanning, Sean W; Mayne, Christopher G; Dharmarajan, Venkatasubramanian; Carlson, Kathryn E; Martin, Teresa A; Novick, Scott J; Toy, Weiyi; Green, Bradley; Panchamukhi, Srinivas; Katzenellenbogen, Benita S; Tajkhorshid, Emad; Griffin, Patrick R; Shen, Yang; Chandarlapaty, Sarat; Katzenellenbogen, John A; Greene, Geoffrey L

    2016-01-01

    Somatic mutations in the estrogen receptor alpha (ERα) gene (ESR1), especially Y537S and D538G, have been linked to acquired resistance to endocrine therapies. Cell-based studies demonstrated that these mutants confer ERα constitutive activity and antiestrogen resistance and suggest that ligand-binding domain dysfunction leads to endocrine therapy resistance. Here, we integrate biophysical and structural biology data to reveal how these mutations lead to a constitutively active and antiestrogen-resistant ERα. We show that these mutant ERs recruit coactivator in the absence of hormone while their affinities for estrogen agonist (estradiol) and antagonist (4-hydroxytamoxifen) are reduced. Further, they confer antiestrogen resistance by altering the conformational dynamics of the loop connecting Helix 11 and Helix 12 in the ligand-binding domain of ERα, which leads to a stabilized agonist state and an altered antagonist state that resists inhibition. DOI: http://dx.doi.org/10.7554/eLife.12792.001 PMID:26836308

  20. Transgenic expression of the rice Xa21 pattern-recognition receptor in banana (Musa sp.) confers resistance to Xanthomonas campestris pv. musacearum.

    PubMed

    Tripathi, Jaindra N; Lorenzen, Jim; Bahar, Ofir; Ronald, Pamela; Tripathi, Leena

    2014-08-01

    Banana Xanthomonas wilt (BXW), caused by the bacterium Xanthomonas campestris pv. musacearum (Xcm), is the most devastating disease of banana in east and central Africa. The spread of BXW threatens the livelihood of millions of African farmers who depend on banana for food security and income. There are no commercial chemicals, biocontrol agents or resistant cultivars available to control BXW. Here, we take advantage of the robust resistance conferred by the rice pattern-recognition receptor (PRR), XA21, to the rice pathogen Xanthomonas oryzae pv. oryzae (Xoo). We identified a set of genes required for activation of Xa21-mediated immunity (rax) that were conserved in both Xoo and Xcm. Based on the conservation, we hypothesized that intergeneric transfer of Xa21 would confer resistance to Xcm. We evaluated 25 transgenic lines of the banana cultivar 'Gonja manjaya' (AAB) using a rapid bioassay and 12 transgenic lines in the glasshouse for resistance against Xcm. About 50% of the transgenic lines showed complete resistance to Xcm in both assays. In contrast, all of the nontransgenic control plants showed severe symptoms that progressed to complete wilting. These results indicate that the constitutive expression of the rice Xa21 gene in banana results in enhanced resistance against Xcm. Furthermore, this work demonstrates the feasibility of PRR gene transfer between monocotyledonous species and provides a valuable new tool for controlling the BXW pandemic of banana, a staple food for 100 million people in east Africa.

  1. IL-27 Found to Play Significant Role in Conferring HIV Resistance | Poster

    Cancer.gov

    By Nancy Parrish, Staff Writer The human immunodeficiency virus (HIV) targets specific immune cells in the body known as macrophages because these are the cells that eliminate foreign material such as bacteria or viruses. HIV is able to reproduce and spread throughout the body if it can avoid destruction by macrophages. A recent study by Lue Dai, Ph.D., and colleagues revealed that the human cytokine IL-27 helps promote the body’s production of macrophages that are resistant to HIV. The study further found that IL-27 suppresses a gene known as SPTBN1, which facilitates the survival of HIV cells. This breakthrough research was recently published in the Journal of Experimental Medicine.

  2. A Stress-Resistant Lipidomic Signature Confers Extreme Longevity to Humans.

    PubMed

    Jové, Mariona; Naudí, Alba; Gambini, Juan; Borras, Consuelo; Cabré, Rosanna; Portero-Otín, Manuel; Viña, Jose; Pamplona, Reinald

    2017-01-01

    Plasma lipidomic profile is species specific and an optimized feature associated with animal longevity. In the present work, the use of mass spectrometry technologies allowed us to determine the plasma lipidomic profile and the fatty acid pattern of healthy humans with exceptional longevity. Here, we show that it is possible to define a lipidomic signature only using 20 lipid species to discriminate adult, aged and centenarian subjects obtaining an almost perfect accuracy (90%-100%). Furthermore, we propose specific lipid species belonging to ceramides, widely involved in cell-stress response, as biomarkers of extreme human longevity. In addition, we also show that extreme longevity presents a fatty acid profile resistant to lipid peroxidation. Our findings indicate that lipidomic signature is an optimized feature associated with extreme human longevity. Further, specific lipid molecular species and lipid unsaturation arose as potential biomarkers of longevity.

  3. Potentiated DNA Damage Response in Circulating Breast Tumor Cells Confers Resistance to Chemotherapy*

    PubMed Central

    Gong, Chang; Liu, Bodu; Yao, Yandan; Qu, Shaohua; Luo, Wei; Tan, Weige; Liu, Qiang; Yao, Herui; Zou, Lee; Su, Fengxi; Song, Erwei

    2015-01-01

    Circulating tumor cells (CTCs) are seeds for cancer metastasis and are predictive of poor prognosis in breast cancer patients. Whether CTCs and primary tumor cells (PTCs) respond to chemotherapy differently is not known. Here, we show that CTCs of breast cancer are more resistant to chemotherapy than PTCs because of potentiated DNA repair. Surprisingly, the chemoresistance of CTCs was recapitulated in PTCs when they were detached from the extracellular matrix. Detachment of PTCs increased the levels of reactive oxygen species and partially activated the DNA damage checkpoint, converting PTCs to a CTC-like state. Inhibition of checkpoint kinases Chk1 and Chk2 in CTCs reduces the basal checkpoint response and sensitizes CTCs to DNA damage in vitro and in mouse xenografts. Our results suggest that DNA damage checkpoint inhibitors may benefit the chemotherapy of breast cancer patients by suppressing the chemoresistance of CTCs and reducing the risk of cancer metastasis. PMID:25897074

  4. Potentiated DNA Damage Response in Circulating Breast Tumor Cells Confers Resistance to Chemotherapy.

    PubMed

    Gong, Chang; Liu, Bodu; Yao, Yandan; Qu, Shaohua; Luo, Wei; Tan, Weige; Liu, Qiang; Yao, Herui; Zou, Lee; Su, Fengxi; Song, Erwei

    2015-06-12

    Circulating tumor cells (CTCs) are seeds for cancer metastasis and are predictive of poor prognosis in breast cancer patients. Whether CTCs and primary tumor cells (PTCs) respond to chemotherapy differently is not known. Here, we show that CTCs of breast cancer are more resistant to chemotherapy than PTCs because of potentiated DNA repair. Surprisingly, the chemoresistance of CTCs was recapitulated in PTCs when they were detached from the extracellular matrix. Detachment of PTCs increased the levels of reactive oxygen species and partially activated the DNA damage checkpoint, converting PTCs to a CTC-like state. Inhibition of checkpoint kinases Chk1 and Chk2 in CTCs reduces the basal checkpoint response and sensitizes CTCs to DNA damage in vitro and in mouse xenografts. Our results suggest that DNA damage checkpoint inhibitors may benefit the chemotherapy of breast cancer patients by suppressing the chemoresistance of CTCs and reducing the risk of cancer metastasis.

  5. A point mutation in influenza B neuraminidase confers resistance to peramivir and loss of slow binding.

    PubMed

    Baum, Ellen Z; Wagaman, Pamela C; Ly, Linh; Turchi, Ignatius; Le, Jianhua; Bucher, Doris; Bush, Karen

    2003-06-01

    The influenza neuraminidase (NA) inhibitors peramivir, oseltamivir, and zanamivir are potent inhibitors of NAs from both influenza A and B strains. In general, these inhibitors are slow, tight binders of NA, exhibiting time-dependent inhibition. A mutant of influenza virus B/Yamagata/16/88 which was resistant to peramivir was generated by passage of the virus in tissue culture, in the presence of increasing concentrations (0.1-120 microM over 15 passages) of the compound. Whereas the wild type (WT) virus was inhibited by peramivir with an EC(50) value of 0.10 microM, virus isolated at passages 3 and 15 displayed EC(50) values of 10 and >50 microM, respectively. Passage 3 virus contained 3 hemagglutinin (HA) mutations, but no NA mutation. Passage 15 (P15R) virus contained an additional 3 HA mutations, plus the NA mutation His273Tyr. The mechanism of inhibition of WT and P15R NA by peramivir was examined in enzyme assays. The WT and P15R NAs displayed IC(50) values of 8.4+/-0.4 and 127+/-16 nM, respectively, for peramivir. Peramivir inhibited the WT enzyme in a time-dependent fashion, with a K(i) value of 0.066+/-0.002nM. In contrast, the P15R enzyme did not display the property of slow binding and was inhibited competitively with a K(i) value of 4.69+/-0.44nM. Molecular modeling suggested that His273 was relatively distant from peramivir (>5A) in the NA active site, but that Tyr273 introduced a repulsive interaction between the enzyme and inhibitor, which may have been responsible for peramivir resistance.

  6. Negative CD4+TIM-3 Signaling Confers Resistance Against Cold Preservation Damage in Mouse Liver Transplantation

    PubMed Central

    Zhang, Yu; Shen, Xiu-da; Gao, Feng; Nguyen, Terry T.; Shang, Xuanming; Lee, Nayun; Busuttil, Ronald W.; Kupiec-Weglinski, Jerzy W.

    2016-01-01

    Ischemia-reperfusion injury (IRI), an innate immunity-driven local inflammation, remains the major problem in clinical organ transplantation. T cell immunoglobulin and mucin domain (TIM-3) – Galectin-9 (Gal-9) signaling regulates CD4+ Th1 immune responses. Here, we explored TIM-3 – Gal-9 function in a clinically relevant murine model of hepatic cold storage and orthotopic liver transplantation (OLT). C57BL/6 livers, preserved for 20h at 4°C in UW solution, were transplanted to syngeneic mouse recipients. Up-regulation of TIM-3 on OLT-infiltrating activated CD4+ T cells was observed in the early IRI phase (1h). By 6h of reperfusion, OLTs in recipients treated with a blocking anti-TIM-3 Ab were characterized by: 1/ enhanced hepatocellular damage (sALT levels, liver Suzuki's histological score); 2/ polarized cell infiltrate towards Th1/Th17-type phenotype; 3/ depressed T cell exhaustion markers (PD-1, LAG3); and 4/ elevated neutrophil and macrophage infiltration/activation. In parallel studies, adoptive transfer of CD4+ T cells from naïve WT, but not from TIM-3 Tg donors, readily recreated OLT damage in otherwise IR-resistant RAG−/− test recipients. Furthermore, pre-treatment of mice with rGal-9 promoted hepatoprotection against preservation-association liver damage, accompanied by enhanced TIM-3 expression in OLTs. Thus, CD4+ T cell-dependent “negative” TIM-3 costimulation is essential for hepatic homeostasis and resistance against IR stress in OLTs. PMID:25676534

  7. The Haemophilus ducreyi serum resistance antigen DsrA confers attachment to human keratinocytes.

    PubMed

    Cole, Leah E; Kawula, Thomas H; Toffer, Kristen L; Elkins, Christopher

    2002-11-01

    Haemophilus ducreyi is the etiologic agent of the sexually transmitted genital ulcer disease chancroid. H. ducreyi serum resistance protein A (DsrA) is a member of a family of multifunctional outer membrane proteins that are involved in resistance to killing by human serum complement. The members of this family include YadA of Yersinia species, the UspA proteins of Moraxella catarrhalis, and the Eib proteins of Escherichia coli. The role of YadA, UspA1, and UspA2H as eukaryotic cell adhesins and the function of UspA2 as a vitronectin binder led to our investigation of the cell adhesion and vitronectin binding properties of DsrA. We found that DsrA was a keratinocyte-specific adhesin as it was necessary and sufficient for attachment to HaCaT cells, a keratinocyte cell line, but was not required for attachment to HS27 cells, a fibroblast cell line. We also found that DsrA was specifically responsible for the ability of H. ducreyi to bind vitronectin. We then theorized that DsrA might use vitronectin as a bridge to bind to human cells, but this hypothesis proved to be untrue as eliminating HaCaT cell binding of vitronectin with a monoclonal antibody specific to integrin alpha(v)beta(5) did not affect the attachment of H. ducreyi to HaCaT cells. Finally, we wanted to examine the importance of keratinocyte adhesion in chancroid pathogenesis so we tested the wild-type and dsrA mutant strains of H. ducreyi in our swine models of chancroid pathogenesis. The dsrA mutant was less virulent than the wild type in both the normal and immune cell-depleted swine models of chancroid infection.

  8. Ultrasensitive allele-specific PCR reveals rare preexisting drug-resistant variants and a large replicating virus population in macaques infected with a simian immunodeficiency virus containing human immunodeficiency virus reverse transcriptase.

    PubMed

    Boltz, Valerie F; Ambrose, Zandrea; Kearney, Mary F; Shao, Wei; Kewalramani, Vineet N; Maldarelli, Frank; Mellors, John W; Coffin, John M

    2012-12-01

    It has been proposed that most drug-resistant mutants, resulting from a single-nucleotide change, exist at low frequency in human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus (SIV) populations in vivo prior to the initiation of antiretroviral therapy (ART). To test this hypothesis and to investigate the emergence of resistant mutants with drug selection, we developed a new ultrasensitive allele-specific PCR (UsASP) assay, which can detect drug resistance mutations at a frequency of ≥0.001% of the virus population. We applied this assay to plasma samples obtained from macaques infected with an SIV variant containing HIV-1 reverse transcriptase (RT) (RT-simian-human immunodeficiency [SHIV](mne)), before and after they were exposed to a short course of efavirenz (EFV) monotherapy. We detected RT inhibitor (RTI) resistance mutations K65R and M184I but not K103N in 2 of 2 RT-SHIV-infected macaques prior to EFV exposure. After three doses over 4 days of EFV monotherapy, 103N mutations (AAC and AAT) rapidly emerged and increased in the population to levels of ∼20%, indicating that they were present prior to EFV exposure. The rapid increase of 103N mutations from <0.001% to 20% of the viral population indicates that the replicating virus population size in RT-SHIV-infected macaques must be 10(6) or more infected cells per replication cycle.

  9. Map-based Cloning and Characterization of the BPH18 Gene from Wild Rice Conferring Resistance to Brown Planthopper (BPH) Insect Pest

    PubMed Central

    Ji, Hyeonso; Kim, Sung-Ryul; Kim, Yul-Ho; Suh, Jung-Pil; Park, Hyang-Mi; Sreenivasulu, Nese; Misra, Gopal; Kim, Suk-Man; Hechanova, Sherry Lou; Kim, Hakbum; Lee, Gang-Seob; Yoon, Ung-Han; Kim, Tae-Ho; Lim, Hyemin; Suh, Suk-Chul; Yang, Jungil; An, Gynheung; Jena, Kshirod K.

    2016-01-01

    Brown planthopper (BPH) is a phloem sap-sucking insect pest of rice which causes severe yield loss. We cloned the BPH18 gene from the BPH-resistant introgression line derived from the wild rice species Oryza australiensis. Map-based cloning and complementation test revealed that the BPH18 encodes CC-NBS-NBS-LRR protein. BPH18 has two NBS domains, unlike the typical NBS-LRR proteins. The BPH18 promoter::GUS transgenic plants exhibited strong GUS expression in the vascular bundles of the leaf sheath, especially in phloem cells where the BPH attacks. The BPH18 proteins were widely localized to the endo-membranes in a cell, including the endoplasmic reticulum, Golgi apparatus, trans-Golgi network, and prevacuolar compartments, suggesting that BPH18 may recognize the BPH invasion at endo-membranes in phloem cells. Whole genome sequencing of the near-isogenic lines (NILs), NIL-BPH18 and NIL-BPH26, revealed that BPH18 located at the same locus of BPH26. However, these two genes have remarkable sequence differences and the independent NILs showed differential BPH resistance with different expression patterns of plant defense-related genes, indicating that BPH18 and BPH26 are functionally different alleles. These findings would facilitate elucidation of the molecular mechanism of BPH resistance and the identified novel alleles to fast track breeding BPH resistant rice cultivars. PMID:27682162

  10. CerS2 haploinsufficiency inhibits β-oxidation and confers susceptibility to diet-induced steatohepatitis and insulin resistance.

    PubMed

    Raichur, Suryaprakash; Wang, Siew Tein; Chan, Puck Wee; Li, Ying; Ching, Jianhong; Chaurasia, Bhagirath; Chaurasia, Bghagirath; Dogra, Shaillay; Öhman, Miina K; Takeda, Kosuke; Sugii, Shigeki; Pewzner-Jung, Yael; Futerman, Anthony H; Summers, Scott A

    2014-10-07

    Inhibition of ceramide synthesis prevents diabetes, steatosis, and cardiovascular disease in rodents. Six different ceramide synthases (CerS) that differ in tissue distribution and substrate specificity account for the diversity in acyl-chain composition of distinct ceramide species. Haploinsufficiency for ceramide synthase 2 (CerS2), the dominant isoform in the liver that preferentially makes very-long-chain (C22/C24/C24:1) ceramides, led to compensatory increases in long-chain C16-ceramides and conferred susceptibility to diet-induced steatohepatitis and insulin resistance. Mechanistic studies revealed that these metabolic effects were likely due to impaired β-oxidation resulting from inactivation of electron transport chain components. Inhibiting global ceramide synthesis negated the effects of CerS2 haploinsufficiency in vivo, and increasing C16-ceramides by overexpressing CerS6 recapitulated the phenotype in isolated, primary hepatocytes. Collectively, these studies reveal that altering sphingolipid acylation patterns impacts hepatic steatosis and insulin sensitivity and identify CerS6 as a possible therapeutic target for treating metabolic diseases associated with obesity.

  11. Stable expression and functional characterisation of the diamondback moth ryanodine receptor G4946E variant conferring resistance to diamide insecticides

    PubMed Central

    Troczka, Bartlomiej J.; Williams, Alan J.; Williamson, Martin S.; Field, Linda M.; Lüemmen, Peter; Davies, T.G. Emyr

    2015-01-01

    Diamides, such as flubendiamide and chlorantraniliprole, belong to a new chemical class of insecticides that act as conformation-sensitive activators of insect ryanodine receptors (RyRs). Both compounds are registered for use against lepidopteran species such as the diamondback moth, Plutella xylostella, a notorious global pest of cruciferous crops. Recently acquired resistance to diamide insecticides in this species is thought to be due to a target-site mutation conferring an amino acid substitution (G4946E), located within the trans-membrane domain of the RyR, though the exact role of this mutation has not yet been fully determined. To address this we have cloned a full-length cDNA encoding the P. xylostella RyR and established clonal Sf9 cell lines stably expressing either the wildtype RyR or the G4946E variant, in order to test the sensitivity to flubendiamide and chlorantraniliprole on the recombinant receptor. We report that the efficacy of both diamides was dramatically reduced in clonal Sf9 cells stably expressing the G4946E modified RyR, providing clear functional evidence that the G4946E RyR mutation impairs diamide insecticide binding. PMID:26424584

  12. Temperature-sensitive fitness cost of insecticide resistance in Chinese populations of the diamondback moth Plutella xylostella.

    PubMed

    Zhang, Lin Jie; Jing, Yu Pu; Li, Xiao Hui; Li, Chang Wei; Bourguet, Denis; Wu, Gang

    2015-04-01

    Alleles conferring a higher adaptive value in one environment may have a detrimental impact on fitness in another environment. Alleles conferring resistance to pesticides and drugs provide textbook examples of this trade-off as, in addition to conferring resistance to these molecules, they frequently decrease fitness in pesticide/drug-free environments. We show here that resistance to chlorpyrifos, an organophosphate (OP), in Chinese populations of the diamondback moth, Plutella xylostella, is conferred by two mutations of ace1 - the gene encoding the acetylcholinesterase enzyme targeted by OPs - affecting the amino acid sequence of the corresponding protein. These mutations were always linked, consistent with the segregation of a single resistance allele, ace1R, carrying both mutations, in the populations studied. We monitored the frequency of ace1R (by genotyping more than 20 000 adults) and the level of resistance (through bioassays on more than 50 000 individuals) over several generations. We found that the ace1R resistance allele was costly in the absence of insecticide and that this cost was likely recessive. This fitness costs involved a decrease in fecundity: females from resistant strains laid 20% fewer eggs, on average, than females from susceptible strains. Finally, we found that the fitness costs associated with the ace1R allele were greater at high temperatures. At least two life history traits were involved: longevity and fecundity. The relative longevity of resistant individuals was affected only at high temperatures and the relative fecundity of resistant females - which was already affected at temperatures optimal for development - decreased further at high temperatures. The implications of these findings for resistance management are discussed.

  13. A Naturally Occurring Domestic Cat APOBEC3 Variant Confers Resistance to Feline Immunodeficiency Virus Infection

    PubMed Central

    Yoshikawa, Rokusuke; Izumi, Taisuke; Yamada, Eri; Nakano, Yusuke; Misawa, Naoko; Ren, Fengrong; Carpenter, Michael A.; Ikeda, Terumasa; Münk, Carsten; Harris, Reuben S.; Miyazawa, Takayuki; Koyanagi, Yoshio

    2015-01-01

    ABSTRACT Apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like 3 (APOBEC3; A3) DNA cytosine deaminases can be incorporated into progeny virions and inhibit lentiviral replication. On the other hand, viral infectivity factor (Vif) of lentiviruses antagonizes A3-mediated antiviral activities by degrading A3 proteins. It is known that domestic cat (Felis catus) APOBEC3Z3 (A3Z3), the ortholog of human APOBEC3H, potently suppresses the infectivity of vif-defective feline immunodeficiency virus (FIV). Although a recent report has shown that domestic cat encodes 7 haplotypes (hap I to hap VII) of A3Z3, the relevance of A3Z3 polymorphism in domestic cats with FIV Vif has not yet been addressed. In this study, we demonstrated that these feline A3Z3 variants suppress vif-defective FIV infectivity. We also revealed that codon 65 of feline A3Z3 is a positively selected site and that A3Z3 hap V is subject to positive selection during evolution. It is particularly noteworthy that feline A3Z3 hap V is resistant to FIV Vif-mediated degradation and still inhibits vif-proficient viral infection. Moreover, the side chain size, but not the hydrophobicity, of the amino acid at position 65 determines the resistance to FIV Vif-mediated degradation. Furthermore, phylogenetic analyses have led to the inference that feline A3Z3 hap V emerged approximately 60,000 years ago. Taken together, these findings suggest that feline A3Z3 hap V may have been selected for escape from an ancestral FIV. This is the first evidence for an evolutionary “arms race” between the domestic cat and its cognate lentivirus. IMPORTANCE Gene diversity and selective pressure are intriguing topics in the field of evolutionary biology. A direct interaction between a cellular protein and a viral protein can precipitate an evolutionary arms race between host and virus. One example is primate APOBEC3G, which potently restricts the replication of primate lentiviruses (e.g., human immunodeficiency virus type 1

  14. A Novel erm(44) Gene Variant from a Human Staphylococcus saprophyticus Isolate Confers Resistance to Macrolides and Lincosamides but Not Streptogramins.

    PubMed

    Strauss, Christian; Hu, Yanmin; Coates, Anthony; Perreten, Vincent

    2017-01-01

    A novel erm(44) gene variant, erm(44)v, has been identified by whole-genome sequencing in a Staphylococcus saprophyticus isolate from the skin of a healthy person. It has the particularity to