Plant defensins form a family of proteins with a broad spectrum of protective activities against fungi, bacteria, and insects. Furthermore, some plant defensins have revealed anticancer activity. In general, plant defensins are non-toxic to plant and mammalian cells, and interest in using them for biotechnological and medicinal purposes is growing. Recent studies provided significant insights into the mechanisms of action of plant defensins. In this review, we focus on structural and dynamics aspects and discuss structure-dynamics-function relations of plant defensins.

Background. Pine bark beetle Ips acuminatus (Gyllenhal, 1827) is one of the most harmful pests of pine trees as it affects the phloem of the upper part of the stem and branches, disrupting the flow of nutrients and water to the crown. I. acuminatus feeds by plant tissues rich in starch, so α-amylases must play a pivotal role in the carbohydrate metabolism of these insects. However, in conifer bark beetles, α-amylases remain poorly understood. Materials and Methods. To detect the α-amylase activity in the digestive system of I. acuminatus, we obtained extracts from larvae, pupae, and adults that were collected from naturally infested Scots pine. The α-amylase activity of crude extracts from different stages and parts of the bark beetle’s body was assessed using 1% starch agar plates. The quantitative evaluation of the α-amylase inhibitory activity of recombinant defensins PsDef1, PsDef2, and PsDef5.1 was performed using the Bernfeld method. The docking models of Scots pine defensins and Ips typographus L. α-amylase (AmyIp) complexes were predicted using the ClusPro 2.0 web server. Results and Discussion. As a result, we found the presence of α-amylase activity in the digestive systems of both larvae and adults of I. acuminatus, but not in pupae. All tested defensins, PsDef1, PsDef2, and PsDef5.1, exhibited inhibitory activity against insect α-amylase at micromolar concentrations. The IC50 values for these peptides were 4.9±0.6 μM, 4.6±0.8 μM, and 2.8±0.5 μM, respectively. In the PsDefs-AmyIt complexes, a network of hydrogen bonds, ionic bridges, and nonbonded contacts are formed between the enzyme and its inhibitor, which prevents the substrate from reaching the catalytic site. The PsDef5.1-AmyIt complex has the largest interfacial contact area, 2328 Å2, in comparison with two other defensins, which correlates well with the inhibitory activity of defensins in this study. Conclusion. Thus, we have identified α-amylase activity in I. acuminatus and demonstrated the ability of Scots pine defensins to inhibit it, sugges­ting that they play a role in pine defenses against this pest.

Background. Scots pine (Pinus sylvestris L.) is a highly adaptable forest species, yet it faces increasing threats from climate-induced droughts despite its natural stress tolerance. To cope with environmental stressors, plants deploy defense mechanisms, such as antimicrobial peptides (AMPs). However, the role of defensins, a key AMP class, in pine stress responses remains insufficiently explored. Materials and Methods. To investigate the responsiveness of PsDef1–4 genes to environmental stimuli, Scots pine seedlings were exposed to biotic stress (phytopathogenic fungi Fusarium verticillioides F3 and Ophiostoma clavatum B0922, and a beneficial endophytic bacterium Pseudomonas putida P57) and various abiotic stressors, including acidification, cold, heat, drought, salinity, flooding, and heavy metals. Gene expression was analyzed via quantitative RT-PCR. Orthologs of PsDef1–4 were identified in the genome assemblies of Pinus tabuliformis and Pinus taeda. Promoter regions (2 kb upstream) were analyzed for cis-acting regulatory elements using the PlantCARE database. Results and Discussion. In silico analysis of the promoter regions of PtbDef1–4 and PtaDef1,2,4 (orthologs of PsDef1–4) revealed a high proportion (44–57 %) of cis-acting regulatory elements associated with stress responsiveness, suggesting their involvement in plant protection. In vivo gene expression analysis showed that both pathogenic fungi and the endophytic bacterium induced upregulation of PsDef1–4 at 48 h post-inoculation. The responses to abiotic stress varied: drought and flooding increased expression of all four defensin genes, while zinc treatment and cold stress caused strong downregulation. Expression responses to heat, salinity, acidification, and cadmium were gene-specific. Conclusion. Overall, Scots pine defensin genes are responsive not only to pathogenic and beneficial microbes but also to a wide range of abiotic stresses, indicating their broader role in adaptive responses to environmental challenges. These findings highlight defensins as promising candidate genes for breeding programs aimed at developing climate-resilient pine genotypes.

Activation of large conductance calcium-dependent potassium channels (BK channels) affects the membrane repolarization at action potential generation and the resting potential of detrusor smooth muscle cells (SMC). Overactive bladder syndrome (OBS) is one of the complications of diabetes mellitus. Using patch-clamp technique, we have found a significant decrease in potassium current (IBK) through BK channels of isolated detrusor SMC, and a decrease in the amplitude and frequency of BK-mediated spontaneous transient outward currents (STOCs) in rats with streptozotocin-induced diabetes mellitus compared with control animals. Under the diabetes, IBK density at step depolarization to +50 mV averaged (10.0 ± 0.5) pA / pF (the control values were (15.0 ± 0.4) pA / pF), whereas the mean values of the STOC frequency and amplitude at holding potential of -20 mV decreased from (12.0 ± 1.5) Hz to (2.4 ± 0.6) Hz and (0.9 ± 0.1) to 0.5 pA / pF ± 0.1 pA / pF, respectively. Using real time polymerase chain reaction (RT-PCR), it was found that mRNA expression of primary pore-forming KCa1.1-subunit of the BK channel increased in diabetes, whilst that for the auxiliary BKCaβ1-subunit decreased. It has been concluded that the observed changes in BK-channel currents in diabetes may enhance excitability of detrusor SMC, thereby promoting myogenic OBS. However, more studies are needed to determine how a decrease in BKCa β1 expression affects the functional properties of BK channels in diabetes, and to identify the type and direction of calcium signal changes modulating channel activation.

Over the past two decades, dieback of Pinus sylvestris L. stands has increased across Europe, largely due to mass outbreaks of the bark beetle, in particular, Ips acuminatus Gyll. (Coleoptera: Curculionidae). This beetle causes mechanical damage and vectors pathogenic fungi, including ophiostomatoid species that induce blue-stain. Ophiostoma clavatum Math.-Käärik is the most frequently reported fungal associate, yet its occurrence had not been documented in Ukraine. While ophiostomatoid fungi are well studied in pine pathogenesis, the role of fast-growing associates such as Fusarium spp., remains poorly understood. This study aimed to identify the dominant Ophiostoma and Fusarium species associated with I. acuminatus in western Ukraine and to evaluate their pathogenicity on pine seedlings. Isolates from beetle abdomens and blue-stained wood were identified as O. clavatum based on morphology and molecular markers (ITS, TUB, TEF1-α). Pathogenicity tests showed that O. clavatum acts as a weak phytopathogen. The dominant Fusarium morphotype from blue-stained wood was identified as Fusarium verticillioides (Sac) Nirenberg, which induced necrosis and tissue maceration on pine seedlings. In dual culture, F. verticillioides displayed strong competitive dominance over O. clavatum . This study provides the first record of O. clavatum associated with I. acuminatus in Ukraine, extending its known European distribution. The observed pathogenicity and competitive ability of F. verticillioides suggest it may contribute to Scots pine decline, warranting further investigation.

We trained a fastai/PyTorch-based neural network to distinguish between four classes of images drawn by healthy and mentally ill people. A comparative evaluation involving Gemini, ChatGPT, Grok, and Qwen revealed that AI simulates psychopathological markers with such accuracy that our network classifies them as "schizophrenic" with 75% confidence . The model is available as a Telegram bot for open testing.