Background: Increase in vancomycin (Van)-resistant bacterial strains including vancomycin-resistant Staphylococcus aureus (VRSA) and lack of new effective antibiotics have become a formidable health problem. Materials and methods: We designed a new conjugate composed of Van and a peptide Hecate (Hec; Van/Hec), and its potential antimicrobial activity was evaluated. Results: Results from disk diffusion test, time-kill assay, determination of minimum inhibitory concentration (MIC), microscopy, and comet assay showed strong antimicrobial effects of Van/Hec against wild-type, methicillin-resistant Staphylococcus aureus (MRSA) and VRSA. Microscopy revealed that the exposure to Van/Hec results in disruption of bacterial cell integrity in all tested strains, which was not observed in case of Van or Hec alone. Conclusion: Overall, we showed that the preparation of conjugates from antibiotics and biologically active peptides could help us to overcome the limitation of the use of antibiotic in the treatment of infections caused by multidrug-resistant bacteria.

The physical and chemical synthesis methods of quantum dots (QDs) are generally unfavorable for biological applications. To overcome this limitation, the development of a novel “green” route to produce highly-fluorescent CdSe QDs constitutes a promising substitute approach. In the present work, CdSe QDs were biosynthesized in yeast Saccharomyces cerevisiae using a novel method, where we showed for the first time that the concentration of tryptone highly affects the synthesis process. The optimum concentration of tryptone was found to be 25 g/L for the highest yield. Different methods were used to optimize the QD extraction from yeast, and the best method was found to be by denaturation at 80 °C along with an ultrasound needle. Multiple physical characterizations including transmission electron microscopy (TEM), dynamic light scattering (DLS), energy-dispersive X-ray spectroscopy (EDX), and spectrophotometry confirmed the optical features size and shape distribution of the QDs. We showed that the novel conjugate of the CdSe QDs and a cell-penetrating peptide (hecate) can detect bacterial cells very efficiently under a fluorescent microscope. The conjugate also showed strong antibacterial activity against vancomycin-resistant Staphylococcus aureus (VRSA), methicillin-resistant Staphylococcus aureus (MRSA), and Escherichia coli, which may help us to cope with the problem of rising antibiotic resistance.

Cercospora leaf spot (CLS), caused by the fungal pathogen Cercospora beticola, is the most important foliar pathogen of sugar beet worldwide. Extensive reliance on fungicides to manage CLS has resulted in the evolution of fungicide resistance in C. beticola worldwide, including populations in the Czech Republic. One important class of fungicides used to manage CLS is the sterol demethylation inhibitors (DMI). The aim of our study was to assess DMI resistance in C. beticola from the Czech Republic and elucidate the molecular basis of DMI resistance in this population. A total of 50 isolates were collected in 2018 and 2019 from the major sugar beet growing regions of the Czech Republic and assessed for in vitro sensitivity to the DMI fungicides propiconazole, prochloraz, and epoxiconazole. These analyses identified three strains that exhibited 50% effective concentration (EC₅₀) values > 1.0 μg mL^–1 against respective fungicides, which were therefore considered resistant. In contrast, strains that exhibited lowest EC₅₀ values were considered sensitive. To explore the molecular basis of resistance in these three strains, the cytochrome P450-dependent sterol 14α-demethylase (Cyp51) gene was sequenced. Sequence analysis identified a Y464S mutation in all three resistant strains. To assess whether Cyp51 gene expression may play a role in DMI resistance, selected strains were grown in vitro with and without fungicide treatment. These analyses indicated that Cyp51 gene expression was significantly induced after fungicide treatment. Thus, we conclude that Y464S point mutation along with induced Cyp51 gene overexpression is likely responsible for resistance against DMI fungicides in C. beticola from the Czech Republic.

The long-term storage of boar sperm presents an ongoing challenge, and the modification of the cryoprotective compounds in semen extenders is crucial for improving cryopreservation’s success rate. The aim of our study was to reduce the percentage of glycerol in the extender by elimination or substitution with biocompatible, non-toxic polysaccharides. For boar semen extender improvement, we tested a novel modification with the polysaccharides dextran and pentaisomaltose in combination with unique in silico predictive modeling. We targeted the analysis of in vitro qualitative sperm parameters such as motility, viability, mitochondrial activity, acrosome integrity, and DNA integrity. Non-penetrating polysaccharide-based cryoprotective agents interact with sperm surface proteins such as spermadhesins, which are recognized as fertility markers of boar sperm quality. The in silico docking study showed a moderate binding affinity of dextran and pentaisomaltose toward one specific spermadhesin known as AWN, which is located in the sperm plasma membrane. Pentaisomaltose formed a hydrophobic pocket for the AWN protein, and the higher energy of this protein–ligand complex compared with dextran was calculated. In addition, the root mean square deviation (RMSD) analysis for the molecular dynamics (MD) of both polysaccharides and AWN simulation suggests their interaction was highly stable. The in silico results were supported by in vitro experiments. In the experimental groups where glycerol was partially or entirely substituted, the use of pentaisomaltose resulted in improved sperm mitochondrial activity and DNA integrity after thawing when compared with dextran. In this paper, we demonstrate that pentaisomaltose, previously used for cryopreservation in hematopoietic stem cells, represents a promising compound for the elimination or reduction of glycerol in extenders for boar semen cryopreservation. This novel approach, using in silico computer prediction and in vitro testing, represents a promising technique to help identify new cryoprotectants for use in animal breeding or genetic resource programs.