Zinc pyrithione is a potent inhibitor of PLPro and cathepsin L enzymes with ex vivo inhibition of SARS-CoV-2 entry and replication

Zinc pyrithione (1a), together with its analogues 1b–h and ruthenium pyrithione complex 2a, were synthesised and evaluated for the stability in biologically relevant media and anti-SARS-CoV-2 activity. Zinc pyrithione revealed potent in vitro inhibition of cathepsin L (IC₅₀=1.88 ± 0.49 µM) and PL^Pro (IC₅₀=0.50 ± 0.07 µM), enzymes involved in SARS-CoV-2 entry and replication, respectively, as well as antiviral entry and replication properties in an ex vivo system derived from primary human lung tissue. Zinc complexes 1b–h expressed comparable in vitro inhibition. On the contrary, ruthenium complex 2a and the ligand pyrithione a itself expressed poor inhibition in mentioned assays, indicating the importance of the selection of metal core and structure of metal complex for antiviral activity. Safe, effective, and preferably oral at-home therapeutics for COVID-19 are needed and as such zinc pyrithione, which is also commercially available, could be considered as a potential therapeutic agent against SARS-CoV-2.     

Assessing students’ knowledge of owls from their drawings and written responses

Many children learn about and experience animals in the everyday environment where they live and attend school. One way to obtain information about children’s understanding of concepts or phenomena is by using their drawings in combination with written responses or interviews. This study assesses how much Slovenian students 10–15 years old (in sixth to ninth grade) know about owls by analysing their drawings and written responses. The study included 473 students. From assessing students’ drawings and written responses, it can be concluded that the respondents had some knowledge of owls’ appearance, their behaviours, diet and habitats. The differences between students in different grades regarding the representations of owls was not statistically significant. Some students had misconceptions about owls, such as the idea that owls can turn their heads 360 degrees, or they confused the long ear-tufts with external parts of the ears. The students’ written responses provided additional information on their ideas about owls; particularly about owls’ specific behaviours, diet, and conservational status. However, some information, such as depicting owls’ body parts and body proportions or their habitats, was more clearly depicted with drawings. One third of the students drew owls in trees and forests, which makes owls good candidates for promoting forest conservation.     

Investigation of antitumor potential of Ni(II) complexes with tridentate PNO acylhydrazones of 2-(diphenylphosphino)benzaldehyde and monodentate pseudohalides

Square-planar azido Ni(II) complex with condensation product of 2-(diphenylphosphino)benzaldehyde and Girard’s T reagent was synthesized and its crystal structure was determined. Cytotoxic activity of the azido complex and previously synthesized isothiocyanato, cyanato and chlorido Ni(II) complexes with this ligand was examined on six tumor cell lines (HeLa, A549, K562, MDA-MB-453, MDA-MB-361 and LS-174) and two normal cell line (MRC-5 and BEAS-2B). All the investigated nickel(II) complexes were cytotoxic against all tumor cell lines. The newly synthesized azido complex showed selectivity to HeLa and A549 tumor cell lines compared to the normal cells (for A549 IC₅₀ was similar to that of cisplatin). Azido complex interferes with cell cycle phase distribution of A549 and HeLa cells and possesses nuclease activity towards supercoiled DNA. The observed selectivity of the azido complex for some tumor cell lines can be connected with its strong DNA damaging activity.     

Cognitive and affective outcomes of teaching about poisonous and venomous animals

ABSTRACT

The use of live animals in instruction plays an important role in biological education, with the intention that attitudes and emotions should be positively influenced. To date, studies in this field have given mixed results, and there has certainly been a lack of studies on student attitudes and knowledge of poisonous and venomous animals. This study focuses on the effect of the use of poisonous and venomous animals in biology instruction. Two treatment groups of Slovenian seventh and eighth graders (N = 123; age 12.3 and 13.2 years, respectively) were compared. The experimental group (N = 82) was given the opportunity to observe with adequate risk assessment live animal species. The observation of live poisonous and venomous animals led to higher values on different attitudinal dimensions. After instruction, we found no differences between both treatment groups in knowledge. Interest in learning about the different poisonous and venomous animals increased significantly. The level of disgust decreased for the viper, spider, and scorpion. However, ‘fear’ seems to be more stable and less influenceable than ‘disgust’. We recommend that students should be offered as many first-hand experiences with live poisonous and venomous animals as possible mainly through informal learning environments, such as zoos.     

Isolation and characterization of Tn917-generated bacitracin deficient mutants of Bacillus licheniformis

Abstract Two Tn917-generated bacitracin deficient mutants of Bacillus licheniformis were isolated. Southern blot analysis of chromosomal DNA extracted from both insertional mutants showed that Tn917 inserted in the vicinity of the gene coding for the enzyme BA2 of the bacitracin synthetase enzyme complex. Measurements of bacitracin synthetase activity in cell-free extracts and positive hybridization signals in the vicinity of the BA2 gene indicate that in both bacitracin deficient mutants Tn917 could be inserted in the BA1 gene or in segments involved in regulation. Thus, it could be possible that the genes for bacitracin synthetase are clustered in the B. licheniformis genome.