The effect of ambient pH modulation on ochratoxin A accumulation by Aspergillus carbonarius

2017 ◽  
Vol 10 (4) ◽  
pp. 339-348 ◽  
Author(s):  
U. Maor ◽  
S. Sadhasivam ◽  
V. Zakin ◽  
D. Prusky ◽  
E. Sionov
Keyword(s):  
Ochratoxin A ◽  
Molecular Mechanisms ◽  
Growth Conditions ◽  
Aspergillus Carbonarius ◽  
High Accumulation ◽  
Host Environment ◽  
Expression Of Genes ◽  
Regulatory Signal ◽  
Concomitant Reduction ◽  
Decay Development

Aspergillus carbonarius, the main cause of severe post-harvest decay of vine fruit, is considered the major source of ochratoxin A (OTA) contamination of grapes and derived products. The factors inducing OTA accumulation by A. carbonarius and its contribution to pathogenicity remain unclear. Present findings indicate that the production of organic acids, such as D-gluconic acid (GLA) and citric acid, by A. carbonarius in the growth medium or in the decayed fruit tissue was directly related to ambient pH reduction. Under these conditions, induced transcript expression of genes involved in OTA biosynthesis occurred concurrently with mycotoxin accumulation. The high accumulation of OTA during acidification process raised the question of its importance in host-pathogen interactions during the fungal colonisation. Treatment of colonised grapes with sodium bicarbonate reduced accumulation of organic acid and OTA with a concomitant reduction in decay development, suggesting that tissue acidification is a significant factor in A. carbonarius pathogenicity. The present findings suggest that ambient pH is a regulatory signal for induction of mycotoxin production by A. carbonarius under the dynamic nutritional growth conditions occurring in culture. Yet the molecular mechanisms of OTA biosynthesis induction during colonisation of the acidic host environment are still unclear and should be further investigated.

scholarly journals Host Factors Modulating Ochratoxin A Biosynthesis during Fruit Colonization by Aspergillus carbonarius

2020 ◽  
Vol 7 (1) ◽  
pp. 10
Author(s):  
Uriel Maor ◽  
Omer Barda ◽  
Sudharsan Sadhasivam ◽  
Yang Bi ◽  
Varda Zakin ◽  
...  
Keyword(s):  
Ochratoxin A ◽  
Sugar Content ◽  
Grape Juice ◽  
Growth Conditions ◽  
Host Factors ◽  
Fungal Colonization ◽  
Toxic Metabolite ◽  
Aspergillus Carbonarius ◽  
The Impact

Aspergillus carbonarius is a strong and consistent ochratoxin A (OTA) producer and considered to be the main source of this toxic metabolite in grapes and grape products such as wine, grape juice and dried vine fruit. OTA is produced under certain growth conditions and its accumulation is affected by several environmental factors, such as growth phase, substrate, temperature, water activity and pH. In this study, we examined the impact of fruit host factors on regulation and accumulation of OTA in colonized grape berries, and assessed in vitro the impact of those factors on the transcriptional levels of the key genes and global regulators contributing to fungal colonization and mycotoxin synthesis. We found that limited sugar content, low pH levels and high malic acid concentrations activated OTA biosynthesis by A. carbonarius, both in synthetic media and during fruit colonization, through modulation of global regulator of secondary metabolism, laeA and OTA gene cluster expression. These findings indicate that fruit host factors may have a significant impact on the capability of A. carbonarius to produce and accumulate OTA in grapes.

scholarly journals Pasteurella multocida Gene Expression in Response to Iron Limitation

2001 ◽  
Vol 69 (6) ◽  
pp. 4109-4115 ◽  
Author(s):  
Michael L. Paustian ◽  
Barbara J. May ◽  
Vivek Kapur
Keyword(s):  
Gene Expression ◽  
Pasteurella Multocida ◽  
Molecular Mechanisms ◽  
Iron Acquisition ◽  
Expression Profiles ◽  
Growth Conditions ◽  
Whole Genome ◽  
Altered Expression ◽  
Expression Of Genes ◽  
Wide Range

ABSTRACT Pasteurella multocida is the causative agent of a wide range of diseases in avian and mammalian hosts. Gene expression in response to low iron conditions was analyzed in P. multocida using whole-genome microarrays. The analysis shows that the expression of genes involved in energy metabolism and electron transport generally decreased 2.1- to 6-fold while that of genes used for iron binding and transport increased 2.1- to 7.7-fold in P. multocida during the first 2 h of growth under iron-limiting conditions compared with controls. Notably, 27% of the genes with significantly altered expression had no known function, illustrating the limitations of using publicly available databases to identify genes involved in microbial metabolism and pathogenesis. Taken together, the results of our investigations demonstrate the utility of whole-genome microarray analyses for the identification of genes with altered expression profiles during varying growth conditions and provide a framework for the detailed analysis of the molecular mechanisms of iron acquisition and metabolism in P. multocida and other gram-negative bacteria.

Effect of water activity and temperature on growth of Aspergillus carbonarius and Aspergillus tubingensis and their interactions on ochratoxin A production

2015 ◽  
Vol 8 (1) ◽  
pp. 99-105 ◽  
Author(s):  
M.L. Chiotta ◽  
D.M. Sosa ◽  
M.L. Ponsone ◽  
S.N. Chulze
Keyword(s):  
Ochratoxin A ◽  
Water Activity ◽  
Grape Juice ◽  
Optimal Growth ◽  
Growth Conditions ◽  
Aspergillus Carbonarius ◽  
Aspergillus Tubingensis ◽  
Defence Reaction ◽  
Aspergillus Section

Aspergillus section Nigri are described as the main source of ochratoxin A (OTA) contamination in grapes and wine worldwide. The grape-growing area in Argentina has a wide latitudinal extension with ecological variations that allow the classification of well-demarcated regions. The aims of this study were: to determine the effect of eco-physiological parameters on growth of Aspergillus tubingensis and Aspergillus carbonarius and to evaluate the interaction between these species on OTA production in synthetic grape juice medium under different water activity (aw) and temperature conditions. The results showed that optimal growth conditions for A. tubingensis and A. carbonarius were 0.980 aw and 28 °C, however A. tubingensis grew faster than A. carbonarius at all temperatures and aw tested. OTA production by A. carbonarius was favoured at 20 °C and 0.950-0.965 aw, during 14 days of incubation. The effect of A. tubingensis on OTA production by A. carbonarius was mainly dependent on temperature. At 35 °C, A. tubingensis reduced the OTA production while this effect was not observed at 20 °C. More OTA could be produced as a defence reaction against fungal competitors to maintain niche colonisation, but in this study no effects by a related species were observed.

Role of Some Neosynthesized Styryl Heterocycles in Ochratoxin A Control in Aspergillus carbonarius

2016 ◽  
Vol 20 (19) ◽  
pp. 2029-2035 ◽  
Author(s):  
Roberto Antonioletti ◽  
Angela Viglianti ◽  
Stefano Cristofoli ◽  
Alessandra Ricelli
Keyword(s):  
Ochratoxin A ◽  
Aspergillus Carbonarius

scholarly journals Transcriptomic Analysis of Short-Term Salt-Stress Response in Mega Hybrid Rice Seedlings

Agronomy ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1328
Author(s):  
Noushin Jahan ◽  
Yang Lv ◽  
Mengqiu Song ◽  
Yu Zhang ◽  
Liangguang Shang ◽  
...  
Keyword(s):  
Salt Stress ◽  
Molecular Mechanisms ◽  
Oryza Sativa L ◽  
Transcriptome Profiling ◽  
Bhlh Transcription Factor ◽  
F1 Hybrid ◽  
Salt Stress Response ◽  
Productivity Losses ◽  
Expression Of Genes ◽  
Trait Locus

Salinity is a major abiotic stressor that leads to productivity losses in rice (Oryza sativa L.). In this study, transcriptome profiling and heterosis-related genes were analyzed by ribonucleic acid sequencing (RNA-Seq) in seedlings of a mega rice hybrid, Liang-You-Pei-Jiu (LYP9), and its two parents 93–11 and Pei-ai64s (PA64s), under control and two different salinity levels, where we found 8292, 8037, and 631 salt-induced differentially expressed genes (DEGs), respectively. Heterosis-related DEGs were obtained higher after 14 days of salt treatment than after 7 days. There were 631 and 4237 salt-induced DEGs related to heterosis under 7-day and 14-day salt stresses, respectively. Gene functional classification showed the expression of genes involved in photosynthesis activity after 7-day stress treatment, and in metabolic and catabolic activity after 14 days. In addition, we correlated the concurrence of an expression of DEGs for the bHLH transcription factor and a shoot length/salinity-related quantitative trait locus qSL7 that we fine-mapped previously, providing a confirmed case of heterosis-related genes. This experiment reveals the transcriptomic divergence of the rice F1 hybrid and its parental lines under control and salt stress state, and enlightens about the significant molecular mechanisms developed over time in response to salt stress.

scholarly journals Frequent gain- and loss-of-function mutations of the BjMYB113 gene accounted for leaf color variation in Brassica juncea

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Guanghui An ◽  
Jiongjiong Chen
Keyword(s):  
Brassica Juncea ◽  
Anthocyanin Biosynthesis ◽  
Color Variation ◽  
Nucleotide Polymorphisms ◽  
Loss Of Function ◽  
High Accumulation ◽  
Single Nucleotide ◽  
Breeding Programs ◽  
Promoter Sequences ◽  
Expression Of Genes

Abstract Background Mustard (Brassica juncea) is an important economic vegetable, and some cultivars have purple leaves and accumulate more anthocyanins than the green. The genetic and evolution of purple trait in mustard has not been well studied. Result In this study, free-hand sections and metabolomics showed that the purple leaves of mustard accumulated more anthocyanins than green ones. The gene controlling purple leaves in mustard, Mustard Purple Leaves (MPL), was genetically mapped and a MYB113-like homolog was identified as the candidate gene. We identified three alleles of the MYB113-like gene, BjMYB113a from a purple cultivar, BjMYB113b and BjMYB113c from green cultivars. A total of 45 single nucleotide polymorphisms (SNPs) and 8 InDels were found between the promoter sequences of the purple allele BjMYB113a and the green allele BjMYB113b. On the other hand, the only sequence variation between the purple allele BjMYB113a and the green allele BjMYB113c is an insertion of 1,033-bp fragment in the 3’region of BjMYB113c. Transgenic assay and promoter activity studies showed that the polymorphism in the promoter region was responsible for the up-regulation of the purple allele BjMYB113a and high accumulation of anthocyanin in the purple cultivar. The up-regulation of BjMYB113a increased the expression of genes in the anthocyanin biosynthesis pathway including BjCHS, BjF3H, BjF3’H, BjDFR, BjANS and BjUGFT, and consequently led to high accumulation of anthocyanin. However, the up-regulation of BjMYB113 was compromised by the insertion of 1,033-bp in 3’region of the allele BjMYB113c. Conclusions Our results contribute to a better understanding of the genetics and evolution of the BjMYB113 gene controlling purple leaves and provide useful information for further breeding programs of mustard.

Herpesvirus-Associated Proliferative Skin Disease in Frogs and Toads: Proposed Pathogenesis

2021 ◽  
pp. 030098582110063
Author(s):  
Francesco C. Origgi ◽  
Patricia Otten ◽  
Petra Lohmann ◽  
Ursula Sattler ◽  
Thomas Wahli ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Rana Temporaria ◽  
Skin Lesions ◽  
Bufo Bufo ◽  
Careful Examination ◽  
Altered Expression ◽  
Expression Of Genes ◽  
Cell Remodeling ◽  
Tissue Changes

A comparative study was carried out on common and agile frogs ( Rana temporaria and R. dalmatina) naturally infected with ranid herpesvirus 3 (RaHV3) and common toads ( Bufo bufo) naturally infected with bufonid herpesvirus 1 (BfHV1) to investigate common pathogenetic pathways and molecular mechanisms based on macroscopic, microscopic, and ultrastructural pathology as well as evaluation of gene expression. Careful examination of the tissue changes, supported by in situ hybridization, at different stages of development in 6 frogs and 14 toads revealed that the skin lesions are likely transient, and part of a tissue cycle necessary for viral replication in the infected hosts. Transcriptomic analysis, carried out on 2 naturally infected and 2 naïve common frogs ( Rana temporaria) and 2 naturally infected and 2 naïve common toads ( Bufo bufo), revealed altered expression of genes involved in signaling and cell remodeling in diseased animals. Finally, virus transcriptomics revealed that both RaHV3 and BfHV1 had relatively high expression of a putative immunomodulating gene predicted to encode a decoy receptor for tumor necrosis factor in the skin of the infected hosts. Thus, the comparable lesions in infected frogs and toads appear to reflect a concerted epidermal and viral cycle, with presumptive involvement of signaling and gene remodeling host and immunomodulatory viral genes.

scholarly journals Ultrastructural and molecular analysis of the origin and differentiation of cells mediating brittle star skeletal regeneration

BMC Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Laura Piovani ◽  
Anna Czarkwiani ◽  
Cinzia Ferrario ◽  
Michela Sugni ◽  
Paola Oliveri
Keyword(s):  
Molecular Mechanisms ◽  
Close Contact ◽  
Skeletal Development ◽  
Morphological Differentiation ◽  
Brittle Star ◽  
Marker Genes ◽  
Body Parts ◽  
Coelomic Cavity ◽  
Expression Of Genes ◽  
Skeletal Regeneration

Abstract Background Regeneration is the ability to re-grow body parts or tissues after trauma, and it is widespread across metazoans. Cells involved in regeneration can arise from a pool of undifferentiated proliferative cells or be recruited from pre-existing differentiated tissues. Both mechanisms have been described in different phyla; however, the cellular and molecular mechanisms employed by different animals to restore lost tissues as well as the source of cells involved in regeneration remain largely unknown. Echinoderms are a clade of deuterostome invertebrates that show striking larval and adult regenerative abilities in all extant classes. Here, we use the brittle star Amphiura filiformis to investigate the origin and differentiation of cells involved in skeletal regeneration using a combination of microscopy techniques and molecular markers. Results Our ultrastructural analyses at different regenerative stages identify a population of morphologically undifferentiated cells which appear in close contact with the proliferating epithelium of the regenerating aboral coelomic cavity. These cells express skeletogenic marker genes, such as the transcription factor alx1 and the differentiation genes c-lectin and msp130L, and display a gradient of morphological differentiation from the aboral coelomic cavity towards the epidermis. Cells closer to the epidermis, which are in contact with developing spicules, have the morphology of mature skeletal cells (sclerocytes), and express several skeletogenic transcription factors and differentiation genes. Moreover, as regeneration progresses, sclerocytes show a different combinatorial expression of genes in various skeletal elements. Conclusions We hypothesize that sclerocyte precursors originate from the epithelium of the proliferating aboral coelomic cavity. As these cells migrate towards the epidermis, they differentiate and start secreting spicules. Moreover, our study shows that molecular and cellular processes involved in skeletal regeneration resemble those used during skeletal development, hinting at a possible conservation of developmental programmes during adult regeneration. Finally, we highlight that many genes involved in echinoderm skeletogenesis also play a role in vertebrate skeleton formation, suggesting a possible common origin of the deuterostome endoskeleton pathway.

Kinetics of Ochratoxin A Production and Accumulation by Aspergillus carbonarius on Synthetic Grape Medium at Different Temperature Levels

2006 ◽  
Vol 71 (6) ◽  
pp. M196-M200 ◽  
Author(s):  
S. Marín ◽  
N. Bellí ◽  
S. Lasram ◽  
S. Chebil ◽  
A.J. Ramos ◽  
...  
Keyword(s):  
Ochratoxin A ◽  
Aspergillus Carbonarius ◽  
Temperature Levels ◽  
Kinetics Of
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