Polyketide synthase gene aolc35-12 controls the differential expression of ochratoxin A gene aoks1 in Aspergillus westerdijkiae

2012 ◽  
Vol 5 (2) ◽  
pp. 177-186 ◽  
Author(s):  
N. Bacha ◽  
F. Mathieu ◽  
T. Liboz ◽  
A. Lebrihi
Keyword(s):  
Differential Expression ◽  
Polyketide Synthase ◽  
Aspergillus Ochraceus ◽  
Predicted Amino Acid Sequence ◽  
Aspergillus Westerdijkiae ◽  
Penicillium Nordicum ◽  
Polyketide Synthase Gene ◽  
In The Wild ◽  
High Degree ◽  
Degree Of Similarity

Ochratoxine A (OTA), a potential human carcinogen is produced by several species of Aspergillus and Penicillium, including Aspergillus westerdijkiae. In this study a putative polyketide synthase gene aolc35-12 has been partially cloned from A. westerdijkiae. The predicted amino acid sequence of the 3.22 kb clone was found to have a high degree of similarity to other previously identified polyketide synthase genes from various OTA-producing fungi including Aspergillus ochraceus, Aspergillus niger, Aspergillus carbonarius and Penicillium nordicum. The aolc35-12 gene was disrupted and inactivated by insertion of Escherichia coli hygromycin B phosphotransferase gene, which resulted in an OTA negative mutant aoΔlc35-12. Genetic complementation confirmed aolc35-12 as OTA-polyketide synthase gene. Furthermore, study of the differential expression of aolc35-12 and a previously identified OTA-polyketide synthase gene, i.e. aoks1, in the wild-type A. westerdijkiae and aoΔlc35-12 mutant revealed that aolc35-12 could code for a certain polyketide compound complementary for the expression of aoks1 and hence for the activation of OTA biosynthesis system in A. westerdijkiae.

A polyketide synthase gene required for ochratoxin A biosynthesis in Aspergillus ochraceus

Microbiology ◽  
2003 ◽  
Vol 149 (12) ◽  
pp. 3485-3491 ◽  
Author(s):  
J. O'Callaghan ◽  
M. X. Caddick ◽  
A. D. W. Dobson
Keyword(s):  
Ochratoxin A ◽  
Polyketide Synthase ◽  
Subtractive Hybridization ◽  
Polyketide Synthases ◽  
Aspergillus Ochraceus ◽  
Predicted Amino Acid Sequence ◽  
Acyl Transferase ◽  
Reverse Transcription Pcr ◽  
Polyketide Synthase Gene

Ochratoxin A is an important nephrotoxic and nephrocarcinogenic mycotoxin, produced by Aspergillus ochraceus as a polyketide-derived secondary metabolite. A portion of a putative polyketide synthase gene (pks) involved in the biosynthesis of this mycotoxin was cloned by using a suppression subtractive hybridization PCR-based approach. The predicted amino acid sequence of the 1·4 kb clone shared 28–35 % identity to acyl transferase regions from fungal polyketide synthases found in the databases. Based on reverse transcription PCR studies, the pks gene is expressed only under ochratoxin A permissive conditions and only during the early stages of the mycotoxin synthesis. A mutant in which the pks gene has been interrupted cannot synthesize ochratoxin A. This report is the first of the cloning and characterization of a gene involved in ochratoxin A biosynthesis.

Using Cluster Analysis to Improve Marketing Experiments

1971 ◽  
Vol 8 (3) ◽  
pp. 340-347 ◽  
Author(s):  
George S. Day ◽  
Roger M. Heeler
Keyword(s):  
Cluster Analysis ◽  
Space Representation ◽  
Reduced Space ◽  
High Degree ◽  
Degree Of Similarity ◽  
Sensitive Experiment ◽  
Selection Of

When the selection of a sample of stores or cities requires a high degree of similarity among the test units in order to ensure a sensitive experiment, the sample may no longer represent the market. These conflicting requirements can be satisfied by choosing the sample from clusters displayed in a reduced space representation of the market.

Are Tetranychus macfarlanei Baker & Pritchard and Tetranychus malaysiensis Ehara (Acari: Tetranychidae) one species? Morphological and molecular evidences for synonymy between these two spider mite species and a note on invasiveness of T. macfarlanei on okra and eggplant in India

2017 ◽  
Vol 22 (4) ◽  
pp. 467
Author(s):  
Mahran Zeity ◽  
Nagappa Srinivas ◽  
Chinnamade Channegowde Gowda
Keyword(s):  
Spider Mite ◽  
Morphological Characters ◽  
Molecular Data ◽  
Mite Species ◽  
Coi Gene ◽  
High Similarity ◽  
Mitochondrial Coi ◽  
Mitochondrial Coi Gene ◽  
High Degree ◽  
Degree Of Similarity

Study of morphological characters of Tetranychus macfarlanei Baker & Pritchard and Tetranychus malaysiensis Ehara revealed high similarity by comparing all the important characters in addition to the characters pointed out by Ehara to separate those two species. Molecular phylogeny of seven Indian populations of T. macfarlanei and one population of T. malaysiensis from Philippines along with few distantly related species of Tetranychus was attempted. High degree of similarity between these two species at mitochondrial COI gene (96%) as well as ITS2 (rDNA) (96–99%) region was evident. Based on both morphological features and molecular data, T. malaysiensis is proposed as a junior synonym of T. macfarlanei based on ICZN’s law of priority. Also more female characters are prompted in this study to distinctly discriminate T. macfarlanei from its most resembling species, Tetranychus ludeni Zacher. Tetranychus macfarlanei has emerged as a pest of several cultivated crop plants in India. 

pks63787, a Polyketide Synthase Gene Responsible for the Biosynthesis of Benzenoids in the Medicinal Mushroom Antrodia cinnamomea

2016 ◽  
Vol 79 (6) ◽  
pp. 1485-1491 ◽  
Author(s):  
Po-Wei Yu ◽  
Ya-Chih Chang ◽  
Ruey-Fen Liou ◽  
Tzong-Huei Lee ◽  
Shean-Shong Tzean
Keyword(s):  
Polyketide Synthase ◽  
Medicinal Mushroom ◽  
Antrodia Cinnamomea ◽  
Polyketide Synthase Gene

scholarly journals The PKS4 Gene of Fusarium graminearum Is Essential for Zearalenone Production

2006 ◽  
Vol 72 (6) ◽  
pp. 3924-3932 ◽  
Author(s):  
Erik Lys�e ◽  
Sonja S. Klemsdal ◽  
Karen R. Bone ◽  
Rasmus J. N. Frandsen ◽  
Thomas Johansen ◽  
...  
Keyword(s):  
Fusarium Graminearum ◽  
High Performance ◽  
Polyketide Synthase ◽  
Wild Type ◽  
Root Infection ◽  
Enoyl Reductase ◽  
Transformation Protocol ◽  
Chromatography Analysis ◽  
In The Wild ◽  
High Level

ABSTRACT Zearalenones are produced by several Fusarium species and can cause reproductive problems in animals. Some aurofusarin mutants of Fusarium pseudograminearum produce elevated levels of zearalenone (ZON), one of the estrogenic mycotoxins comprising the zearalenones. An analysis of transcripts from polyketide synthase genes identified in the Fusarium graminearum database was carried out for these mutants. PKS4 was the only gene with an enoyl reductase domain that had a higher level of transcription in the aurofusarin mutants than in the wild type. An Agrobacterium tumefaciens-mediated transformation protocol was used to replace the central part of the PKS4 gene with a hygB resistance gene through double homologous recombination in an F. graminearum strain producing a high level of ZON. PCR and Southern analysis of transformants were used to identify isolates with single insertional replacements of PKS4. High-performance liquid chromatography analysis showed that the PKS4 replacement mutant did not produce ZON. Thus, PKS4 encodes an enzyme required for the production of ZON in F. graminearum. Barley root infection studies revealed no alteration in the pathogenicity of the PKS4 mutant compared to the pathogenicity of the wild type. The expression of PKS13, which is located in the same cluster as PKS4, decreased dramatically in the mutant, while transcription of PKS4 was unchanged. This differential expression may indicate that ZON or its derivatives do not regulate expression of PKS4 and that the PKS4-encoded protein or its product stimulates expression of PKS13. Furthermore, both the lack of aurofusarin and ZON influenced the expression of other polyketide synthases, demonstrating that one polyketide can influence the expression of others.

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