Typing of Genetic Markers Involved in Stress Response by Fluorescent cDNA-Amplified Fragment Length Polymorphism Technique

Candida diagnostic techniques: a review

Fungal infections (mycoses) represent a major health issue in humans. They have emerged as a global concern for medical professionals by causing high morbidity and mortality. Fungal infections approximately impact one billion individuals per annum and account for 1.6 million deaths. The diagnosis of Candida infections is a challenging task. Laboratory-based Candida species identification techniques (molecular, commercial, and conventional) have been reviewed and summarized. This review aims to discuss the mycoses history, taxonomy, pathogenicity, and virulence characteristics.

Voriconazole resistance genes in Aspergillus flavus clinical isolates

OBJECTIVE

The present study was designed to discover novel biomarkers involved in voriconazole resistance in clinical isolates of Aspergillus flavus.

MATERIALS AND METHODS

Two voriconazole non-wild-type and two voriconazole-wild-type A. flavus clinical isolates were selected to evaluate possible molecular mechanism involved in A. flavus resistance to voriconazole using the mutation assessment, Quantitative real- time PCR of cyp51A and cyp51C genes and complementary DNA- amplified fragment length polymorphism technique.

RESULTS

No mutations were seen in the cyp51A and cyp51C genes in voriconazole non-wild-type isolates compared to wild- type and reference strains. Regarding to mRNA expression results, no changes were observed in expression fold of cyp51A and cyp51C mRNA expression level in first non- wild- type isolate compared to wild-type isolate. For second isolate cyp51C mRNA expression level was down regulated (5.6 fold). The set of genes including ABC fatty acid transporter XM- 002375835 and aldehydereductase XM- 002376518 and three unknown functional genes were identified. Based on results, the over-expression of AKR1 and ABC fatty acid transporter in the voriconazole non- wild- type isolates suggests these genes could represent a novel molecular marker linked to the voriconazole resistance in A. flavus.

CONCLUSION

The results obtained in this study showed a novel finding as the authors identified AKR1 and ABC fatty acid transporter genes as possible voriconazole target genes in Iranian clinical isolates of A. flavus.

Use of AFLP for the study of eukaryotic pathogens affecting humans

Amplified fragment length polymorphism (AFLP) is a genotyping technique based on PCR amplification of specific restriction fragments from a particular genome. The methodology has been extensively used in plant biology to solve a variety of scientific questions, including taxonomy, molecular epidemiology, systematics, population genetics, among many others. The AFLP share advantages and disadvantages with other types of molecular markers, being particularly useful in organisms with no previous DNA sequence knowledge. In eukaryotic pathogens, the technique has not been extensively used, although it has the potential to solve many important issues as it allows the simultaneous examination of hundreds or even thousands of polymorphic sites in the genome of the organism. Here we describe the main applications published on the use of AFLP in eukaryotic pathogens, with emphasis in species of the groups fungi, protozoa and helminths, and discuss the role of this methodology in the context of new techniques derived from the advances of the next generation sequencing.

cDNA-amplified fragment length polymorphism to study the transcriptional responses of Lactobacillus rhamnosus growing in cheese-like medium

AIMS

Lactobacillus rhamnosus is a dominant species during Parmigiano Reggiano cheese ripening and exhibits a great adaptability to unfavourable growth conditions. Gene expression of a Lact. rhamnosus, isolated from Parmigiano Reggiano cheese, grown in a rich medium (MRS) and in a cheese-like medium (CB) has been compared by a novel cDNA-amplified fragment length polymorphism (cDNA-AFLP) protocol.

METHODS AND RESULTS

Two techniques, capillary and gel electrophoresis cDNA-AFLP, were applied to generate unique transcript tags from reverse-transcribed messenger RNA using the immobilization of biotinylated 3'-terminal cDNA fragments on streptavidin-coated Dynabeads. The use of three pairs of primers allowed detecting 64 genes expressed in MRS and 96 in CB. Different transcripts were observed when Lact. rhamnosus was cultured on CB and MRS.

CONCLUSIONS

The cDNA-AFLP approach proved to be able to show that Lact. rhamnosus modifies the expression of a large part of genes when cultivated in CB compared with growth under optimal conditions (MRS). In particular, the profiles of the strain grown in CB were more complex probably because the cells activate different metabolic pathways to generate energy and to respond to the environmental changes.

SIGNIFICANCE AND IMPACT OF STUDY

This is the first research on Lact. rhamnosus isolated from cheese and represents one of the few concerning bacterial transcriptomic analysis towards cDNA-AFLP approaches.