Role of biocontrol yeasts Debaryomyces hansenii and Wickerhamomyces anomalus in plants' defence mechanisms against Monilinia fructicola in apple fruits.

The role of killer yeasts of the species Debaryomyces hansenii and Wickerhamomyces anomalus in biocontrol of Monilinia fructicola, and their involvement in plant defence mechanisms against brown rot in apple fruits, were investigated. D. hansenii KI2a and W. anomalus BS91 strains showed the highest in vitro biocontrol activity, inhibiting mycelium growth by 69.53% and 66.08% respectively, as compared to control fungal cultures. Brown rot on apple fruits was significantly reduced by BS91 and two strains of D. hansenii KI2a and AII4b by 92.46%, 85.10% and 70.02%, respectively, in comparison to infected fruits, which did not receive any pre-treatment. In enzymatic tests, the most significant changes in peroxidase (POD) and catalase (CAT) activities were observed in fruits inoculated either with BS91 followed by M. fructicola infection or with AII4b yeast strain alone, where POD activities were significantly higher by 67% and 54%, respectively, and CAT activities were significantly lower by 65% and 68%, respectively, than in untreated control fruits. These results confirmed the ability of killer yeasts to influence host-defence related enzyme activities in apple fruit tissue and may suggest that AII4b killer strain has a potential as biocontrol agent prior to infection by triggering immune response mechanisms in plant tissue, whereas BS91 strain is the most effective during pathogen infection and could be used as biocontrol agent in postharvest disease onset. Accordingly, the antagonistic strains of W. anomalus BS91 and D. hansenii KI2a and AII4b could be proposed as active ingredients for the development of biofungicide against M. fructicola.

Preparation of Chemically Modified DNA Library for SELEX via Incorporation of CLB-dUTP in Primer Extension Reaction.

Aptamers are single-stranded DNA or RNA molecules which bind with high specificity to the molecular target for which they have been selected. Through a number of unnatural modifications, the diversity of interactions available for this class of molecules can be greatly expanded, potentially leading to better binding properties. Herein we describe a method to prepare an initial chemically modified DNA library for SELEX. It comprises the synthesis of a modified nucleotide in the CuAAC reaction and its purification by an adapted HPLC method. Subsequent stage is the incorporation of the prepared modified nucleotide into a DNA library in a primer extension reaction and a quick and easy method of its purification using an electroelution device. This allows the recovery of the resulting chemically modified ssDNA library with high efficiency to kick off the aptamer selection process.

The Role of Plasma Membrane Pleiotropic Drug Resistance Transporters in the Killer Activity of Debaryomyces hansenii and Wickerhamomyces anomalus Toxins.

The killer strains of Debaryomyces hansenii and Wickerhamomyces anomalus species secrete antimicrobial proteins called killer toxins which are active against selected fungal phytopathogens. In our research, we attempted to investigate the role of plasma membrane pleiotropic drug resistance (PDR) transporters (Pdr5p and Snq2p) in the mechanism of defense against killer toxins. Saccharomyces cerevisiae mutant strains with strengthened or weakened pleiotropic drug resistance due to increased or reduced number of mentioned PDR efflux pumps were tested for killer toxin susceptibility. The present study demonstrates the influence of the Snq2p efflux pump in immunity to W.anomalus BS91 killer toxin. It was also shown that the activity of killer toxins of D. hansenii AII4b, KI2a, MI1a and CBS767 strains is regulated by other transporters than those influencing W. anomalus killer toxin activity. In turn, this might be related to the functioning of the Pdr5p transporter and a complex cross-talk between several regulatory multidrug resistance networks. To the best of our knowledge, this is the first study that reports the involvement of PDR transporters in the cell membrane of susceptible microorganisms in resistance to killer yeasts' toxins.

Congenital midgut volvulus associated with fetal anemia.

Congenital volvulus is a life-threatening condition, both for the fetus and for the newborn. A volvulus is a twist of small bowel loops or a proximal part of the colon around the mesenteric artery or its branches. The potential consequences of volvulus are ileus and necrosis of the intestinal wall. Prenatal diagnosis of midgut volvulus is difficult. It should be suspected antenatally when polyhydramnios, intestinal dilatation, ascites and/or signs of fetal anemia are present on ultrasound assessment. We report a case of a congenital midgut volvulus associated with fetal anemia. The fetal ultrasound performed at 32 weeks' gestation showed a polyhydramnios, hydrothorax, thick ascites accumulation around the liver and the suspicion of a dilated bowel loop. Additionally, Doppler examination showed an increased value of peak systolic velocity in the middle cerebral artery. Cordocentesis confirmed significant fetal anemia. At 34 weeks, because of the suspicion of idiopathic meconium ileus and secondary anemia, a Cesarean section was performed after the administration of steroids. During the laparatomy, performed postnatally, a midgut volvulus was diagnosed. The affected portion of the ileum was resected and end-to-end anastomosis performed. An antenatal diagnosis of midgut volvulus should be considered when signs of fetal anemia, including an increased value of peak systolic velocity in the middle cerebral artery, are present with polyhydramnios, fetal ascites, dilated bowel loops on antenatal ultrasound. An assessment of the fetal hemodynamic status should be a part of the ultrasound assessment for patients with nonspecific fetal bowel pathologies, including congenital volvulus.