Spores Research Articles

Identification of the chaA and fwA Spore Color Genes of Aspergillus nidulans.

Wild-type Aspergillus nidulans asexual spores (conidia) are green due to a pigment that protects the spores against ultraviolet light. The pigment is produced by a biosynthetic pathway, the genes of which are dispersed in the genome. The backbone molecule of the pigment is a polyketide synthesized by a polyketide synthase encoded by the wA gene. If wA is not functional, the conidia are white. The polyketide is modified by a laccase encoded by the yA gene and inactivation of yA in an otherwise wild-type background results in yellow spores. Additional spore color mutations have been isolated and mapped to a locus genetically, but the genes that correspond to these loci have not been determined. Spore color markers have been useful historically, and they remain valuable in the molecular genetics era. One can determine if a transforming fragment has been successfully integrated at the wA or yA locus by simply looking at the color of transformant conidia. The genes of the potentially useful color loci chaA (chartreuse conidia) and fwA (fawn conidia) have not been identified previously. We chose a set of candidate genes for each locus by comparing the assembled genome with the genetic map. By systematically deleting these candidate genes, we identified a cytochrome P450 gene (AN10028) corresponding to chaA. Deletions of this gene result in chartreuse conidia and chartreuse mutations can be complemented in trans by a functional copy of this gene. With fwA, we found that the existing fawn mutation, fwA1, is a deletion of 2241 base pairs that inactivates three genes. By deleting each of these genes, we determined that fwA is AN1088, an EthD domain protein. Deletion of AN1088 results in fawn conidia as expected. Neither deletion of chaA nor fwA restricts growth and both should be valuable target loci for transformations. Combinations of deletions have allowed us to investigate the epistasis relationships of wA, yA, chaA and fwA.

Atmospheric non-thermal plasma inactivation of Ascosphaera apis, the causative agent of chalkbrood disease in honeybee

Ascosphaera apis is a worldwide pathogenic fungi of honeybees that can cause a decline in bee populations. In this study, we investigated the antifungal activity of non-thermal plasma on fungal growth. Spore inactivation after exposure to gas plasma by liquid phase and plasma activated water (PAW) and pathogenicity of A. apis in vivo were also examined. The results demonstrated that the mycelial growth of fungi was completely inhibited after argon plasma treatment. Both gas plasma and PAW exposures resulted in a significant decrease of A. apis spore numbers, maximum reduction of 1.71 and 3.18-fold, respectively. Germinated fungal spores on potato dextrose agar were also reduced after plasma treatment. SEM analysis revealed a disruption in the morphological structure of the fungal spores. The pathogenicity of A. apis on honeybee larvae was decreased after spores treated by gas plasma and PAW with a disease inhibition of 63.61 ± 7.28% and 58.27 ± 5.87%, respectively after 7 days of cultivation. Chalkbrood in honey bees have limited control options and our findings are encouraging. Here, we demonstrate a possible alternative control method using non-thermal plasma for chalkbrood disease in honeybees.

AwSclB regulates a network for Aspergillus westerdijkiae asexual sporulation and secondary metabolism independent of the fungal light control

As a prevalent pathogenic fungus, Aspergillus westerdijkiae poses a threat to both food safety and human health. The fungal growth, conidia production and ochratoxin A (OTA) in A. weterdijkiae are regulated by many factors especially transcription factors. In this study, a transcription factor AwSclB in A. westerdijkiae was identified and its function in asexual sporulation and OTA biosynthesis was investigated. In addition, the effect of light control on AwSclB regulation was also tested. The deletion of AwSclB gene could reduce conidia production by down-regulation of conidia genes and increase OTA biosynthesis by up-regulation of cluster genes, regardless under light or dark conditions. It is worth to note that the inhibitory effect of light on OTA biosynthesis was reversed by the knockout of AwSclB gene. The yeast one-hybrid assay indicated that AwSclB could interact with the promoters of BrlA, ConJ and OtaR1 genes. This result suggests that AwSclB in A. westerdijkiae can directly regulate asexual conidia formation by activating the central developmental pathway BrlA-AbaA-WetA through up-regulating the expression of AwBrlA, and promote the light response of the strain by activating ConJ. However, AwSclB itself is unable to respond to light regulation. This finding will deepen our understanding of the molecular regulation of A. westerdijkiae development and secondary metabolism, and provide potential targets for the development of new fungicides.

Characterization of Extracellular Chitinase from Bacillus cereus SAHA 12.13 and Its Potency as a Biocontrol of Curvularia affinis

Bacillus cereus SAHA 12.13 can produce chitinase, an enzyme that digests chitin in the main compounds of cell walls, mycelia, and spores in pathogenic fungi that cause leaf spots on oil palm plants such as Curvularia affinis. This study aims to determine the properties of the chitinase enzyme B. cereus SAHA 12.13 that can inhibit the growth of C. affinis. Chitinase enzyme production and characterization were measured using the Spindler method. Antagonism test against pathogenic fungi using dual culture method by testing cell culture and enzyme crude extract. This result showed that the isolate produced a high level of specific chitinase activity at 37 °C for 45 h of incubation with 8.45 U mg-1 proteins with a growth rate (k) of 0.25 generation/h, and the generation time was 3.96 h/generation. The optimum chitinase activity was achieved at pH 7.0 and 45 °C and was stable for 3 h with a half-life (t1/2) of 770 min. The crude enzyme and cell culture of strain can inhibit the growth of C. affinis by 36.27±0.043% and 34.25±0.041%, respectively. These characteristics indicate that B. cereus strain SAHA12.13 can be used to inhibit C. affinis, which causes leaf blight of oil palm, under varying pH and temperature conditions.

Assessment of mould remediation in a healthcare setting following extensive flooding

A new hospital building was close to completion when a large pipe carrying clean water broke, causing extensive flooding. To determine the flood-associated fungal risk to susceptible patients who would use that building. Though standard flood remediation by the builders was relatively straightforward, there was no model for specialist assessment of patient risk due to the flood-associated mould growth. As levels of background airborne fungal spores can be expected to vary significantly over time, we could not use absolute levels to indicate either an excess of airborne fungal spores or successful remediation. Therefore it was decided to use weekly settle plates, exposed at the same time in flooded (test) and equivalent non-flooded (control) areas to compensate for variations in background levels. Flood-related risk was estimated by the ratio between fungal colonies on the test and control sets of settle plates, rather than absolute number. Whereas the physical flood remediation, including the use of 'anti-fungal' treatments, was completed in three weeks post flooding, fungal contamination in flooded areas took 38 weeks to return to control levels and remained so for a further six weeks of observation. By the use of this method, we were able to assure the absence of flood-associated fungal risk to susceptible patients who would use that building. We recommend that infection prevention and control teams consider using this approach should they be faced with similar situations.

Status of endogenous endomycorrhizal fungi associated with cowpea (<i>Vigna unguiculata</i> L.) in the Sudano-Sahelian zone of Cameroon

The Sudano-Sahelian part of Cameroon is known for its severe climatic conditions and low soil fertility. Local farmers use chemical fertilisers to increase crop production, usually without moderation. As a result, there is environmental pollution such as soil acidification, production of greenhouse gases, and increased eutrophication. To face this situation, scientific research recommends ecological solutions such as bio-fertilisers to enhance soil fertility. In this context, the mycorrhiza symbiosis technology deserves special attention. Indeed, it is a beneficial association between soil fungi (Glomeromycota) and the roots of more than 85% of plants; the evaluation of the agronomic potential of these microorganisms has shown spectacular results under field conditions. This study analyses the status of indigenous arbuscular mycorrhizal fungi in the cowpea rhizosphere in the agro-ecological zone 1 of Cameroon. For this purpose, soil samples were collected from the Far North and North regions of Cameroon. Composite soil samples were obtained by mixing soils collected from three divisions per region. Cowpea was grown in pots on these composite soil samples for 3 months. At maturity, spores of mycorrhizal fungi were isolated and parameters including mycorrhization frequency and intensity, the specific spore’s density and richness were evaluated. The spores were characterised according to morpho-anatomical criteria. The results established that between localities, mycorrhization frequency varied between 7-19%; mycorrhization intensity, 7-17.28%; specific density, 0.66-44% and specific richness, 2-4%. Eight specimens of arbuscular mycorrhizal fungi in six genera were characterised: Acaulospora (A. kentinensis, A. myriocarpa); Ambispora sp; Diversispora epigae, Funneliformis mossea, Glomus (G. constrictum, G. manihotis, and G. maculosum) and Rhizophagus intraradices. G. constritum was predominant in all the studied sites, followed by R. intraradices, while Acaulospora myriocarpa was the rarest. These results pave the way for the selection of indigenous arbuscular mycorrhiza fungi for ecological cowpea production in this area.

Observation of a Bone Invasion Model of Aspergillus fumigatus In Vitro and Analysis of the Antifungal Susceptibility.

Recently, the prevalence of invasive fungal infections has been on the rise, and one of the prevalent symptoms frequently observed is bone deterioration and bone loss. Using an in vitro model we studied how Aspergillus fumigatus invades the bone. Pathological analysis was then employed to observe the structure and distinctive features of the invading fungal elements within the bone invasion model. Meanwhile, the antifungal effects of itraconazole, voriconazole, posaconazole, and amphotericin B were evaluated. The pathological findings showed that in the experimental group, fungal spores and hyphae invaded the bone tissue or were observed growing in the vicinity of the bone edge tissues, as indicated by both HE and PAS staining. In contrast, no fungal elements were observed in the control group, indicating that the in vitro bone invasion model of A. fumigatus was successfully constructed. Furthermore, the findings from the antifungal sensitivity test demonstrated that the lowest effective concentrations of antifungal drugs against the bone invasion model were as follows: 4μg/ml for itraconazole, 0.5μg/ml for voriconazole, 2μg/ml for posaconazole, and 2μg/ml for amphotericin B. The successful construction of the bone invasion model of A. fumigatus has provided a solid basis for future investigations into the mechanisms underlying A. fumigatus bone invasion and the study of its virulence factors. Utilizing bone models is of utmost importance in advancing the development of novel antifungal treatment approaches, as well as in effectively preventing and treating fungal bone invasion and osteolytic diseases.

Genome analysis of Pseudomonas strain 4B with broad antagonistic activity against toxigenic fungi.

Pseudomonas sp. 4B isolated from the effluent pond of a bovine abattoir was investigated as antifungal against toxigenic fungi. The complete genome of Pseudomonas 4B was sequenced using the Illumina MiSeq platform. Phylogenetic analysis and genome comparisons indicated that the strain belongs to the Pseudomonas aeruginosa group. In silico investigation revealed gene clusters associated with the biosynthesis of several antifungals, including pyocyanin, rhizomide, thanamycin, and pyochelin. This bacterium was investigated through antifungal assays, showing an inhibitory effect against all toxigenic fungi tested. Bacterial cells reduced the diameter of fungal colonies, colony growth rate, and sporulation of each indicator fungi in 10-day simultaneous growing tests. The co-incubation of bacterial suspension and fungal spores in yeast extract-sucrose broth for 48h resulted in reduced spore germination. During simultaneous growth, decreased production of aflatoxin B1 and ochratoxin A by Aspergillus flavus and Aspergillus carbonarius, respectively, was observed. Genome analysis and in vitro studies showed the ability of P. aeruginosa 4B to reduce fungal growth parameters and mycotoxin levels, indicating the potential of this bacterium to control toxigenic fungi. The broad antifungal activity of this strain may represent a sustainable alternative for the exploration and subsequent use of its possible metabolites in order to control mycotoxin-producing fungi.

An apoptosis-inducing factor controls programmed cell death and laccase expression during fungal interactions

Apoptotic-like programmed cell death (PCD) is one of the main strategies for fungi to resist environmental stresses and maintain homeostasis. The apoptosis-inducing factor (AIF) has been shown in different fungi to trigger PCD through upregulating reactive oxygen species (ROS). This study identified a mitochondrial localized AIF homolog, CcAIF1, from Coprinopsis cinerea monokaryon Okayama 7. Heterologous overexpression of CcAIF1 in Saccharomyces cerevisiae caused apoptotic-like PCD of the yeast cells. Ccaif1 was increased in transcription when C. cinerea interacted with Gongronella sp. w5, accompanied by typical apoptotic-like PCD in C. cinerea, including phosphatidylserine externalization and DNA fragmentation. Decreased mycelial ROS levels were observed in Ccaif1 silenced C. cinerea transformants during cocultivation, as well as reduction of the apoptotic levels, mycelial growth, and asexual sporulation. By comparison, Ccaif1 overexpression led to the opposite phenotypes. Moreover, the transcription and expression levels of laccase Lcc9 decreased by Ccaif1 silencing but increased firmly in Ccaif1 overexpression C. cinerea transformants in coculture. Thus, in conjunction with our previous report that intracellular ROS act as signal molecules to stimulate defense responses, we conclude that CcAIF1 is a regulator of ROS to promote apoptotic-like PCD and laccase expression in fungal-fungal interactions. In an axenic culture of C. cinerea, CcAIF1 overexpression and H2O2 stimulation together increased laccase secretion with multiplied production yield. The expression of two other normally silent isozymes, Lcc8 and Lcc13, was unexpectedly triggered along with Lcc9.Key points• Mitochondrial CcAIF1 induces PCD during fungal-fungal interactions• CcAIF1 is a regulator of ROS to trigger the expression of Lcc9 for defense• CcAIF1 overexpression and H2O2 stimulation dramatically increase laccase production

The Penicillin saga: a different tale

The Sumerians, but also the ancient Egyptians, as well as Greeks and Indians, used extracts of some plants and fungi for the treatment of infections. Henryk Adam Aleksander Pius Sienkiewicz (1846 - 1916), the author of Quo Vadis, Nobel Prize for Literature in 1905, in his novel “With iron and with fire” reports that during the 17th-century in Poland, wet bread was mixed with cobwebs (which often contained fungal spores) to heal wounds. In the same period, in England, in the book entitled Pharmacopoeia Londinensis, the apothecary and botanist John Parkinson (1567 - 1650) recommended the use of molds as a medical treatment for many infectious diseases that affect humans. These treatments often work since many organisms, including many species of mold, naturally produce antibiotic substances. However, ancient practitioners could not accurately identify or isolate the active components of these organisms. Similar experiences and evidence have been found in many other countries, including Italy. For example, Bartolomeo Bizio (1791 - 1862), found in 1821, that the red color assumed by “polenta” (a corn meal dish) was due to a bacterium that he named Serratia marcescens and that its development was inhibited by the presence of mold. After 1850, thanks to the progress of chemistry, the chemotherapy concept for the treatment of infectious diseases began to assert itself. Consequently, some effective chemical compounds were synthesized (for example sodium arsenylate by Antoine Béchamp in 1859 and used, at that time, against sleeping sickness and other trypanosomiasis. It was later abandoned due to its remarkable toxicity). However, thanks to Louis Pasteur (1822 - 1895), in the seventies and eighties of the nineteenth century, the interest in substances of natural origin returned. Pasteur in fact highlighted both the inhibiting action of molds on the development of some bacteria and the antagonism between different bacteria. These observations were taken up by Arnaldo Cantani (1837 - 1893), who tried, with poor results, to apply Pasteur’s concept, developing bacteriotherapy (fight against pathogenic bacteria with other harmless bacteria) to treat tuberculosis.

Mechanism of inactivation of Aspergillus flavus spores by dielectric barrier discharge plasma

Dielectric barrier discharge plasma (DBDP) displays strong against fungal spores, while its precise mechanism of spore inactivation remains inadequately understood. In this study, we applied morphological, in vivo and in vitro experiments, transcriptomics, and physicochemical detection to unveil the potential molecular pathways underlying the inactivation of Aspergillus flavus spores by DBDP. Our findings suggested that mycelium growth was inhibited as observed by SEM after 30 s treatment at 70 kV, meanwhile spore germination ceased and clustering occurred. It led to the release of cellular contents and subsequent spore demise by disrupting the integrity of spore membrane. Additionally, based on the transcriptomic data, we hypothesized that the induction of spore inactivation by DBDP might be associated with downregulation of genes related to cell membranes, organelles (mitochondria), oxidative phosphorylation, and the tricarboxylic acid cycle. Subsequently, we validated our transcriptomic findings by measuring the levels of relevant enzymes in metabolic pathways, such as superoxide dismutase, acetyl-CoA, total dehydrogenase, and ATP. These physicochemical indicators revealed that DBDP treatment resulted in mitochondrial dysfunction, redox imbalance, and inhibited energy metabolism pathways. These findings were consistent with the transcriptomic results. Hence, we concluded that DBDP accelerated spore rupture and death via ROS-mediated mitochondrial dysfunction, which does not depend on cell membranes.

Study of the fungicidal effect of the chimeric form of interferon alpha-2b in relation to fungi-pathogens of plants and animals

The purpose of this study is to evaluate the fungicidal effect of a chimeric form of recombinant interferon alpha-2b, fused with human apolipoprotein A-I, obtained by biosynthesis in the yeast Pichia рastoris, against significant fungal pathogens – pathogens of human and plant diseases.Material and methods. The fungicidal activity of the chimeric cytokine was assessed using the agar block method against fungal pathogens: Alternaria alternata, Fusarium oxysporum, Aspergillus spp. and Penicillum spp. The fungicidal effect was assessed visually and by microscopy of a section of the fungal body stained with methylene blue, the germination of fungal spores – by subculture, the cytotoxicity of interferon preparations – on Vero cell culture.Results and discussion. The studied recombinant interferons suppress the growth and reproduction of pathogenic fungi. Chimeric IFN has the greatest effect against pathogenic fungi A. alternate, Penicillum at a concentration of 15 ng/ml; inhibition of sporulation of fungi F. oxysporum and Aspergillus up to 87 % is achieved at a concentration of 150 ng/ml. The cytotoxicity of the new chimeric cytokine is 5,8 μg/ml, which is significantly more than toxic concentrations for fungi.Conclusions. The chimeric form of interferon alpha-2b can be used as an immunotherapeutic agent with fungicidal activity.

Antifungal Resistance in Pulmonary Aspergillosis.

Aspergilli may cause various pulmonary diseases in humans, including allergic bronchopulmonary aspergillosis (ABPA), chronic pulmonary aspergillosis (CPA), and acute invasive pulmonary aspergillosis (IPA). In addition, chronic colonization may occur in cystic fibrosis (CF). Aspergillus fumigatus represents the main pathogen, which may employ different morphotypes, for example, conidia, hyphal growth, and asexual sporulation, in the various Aspergillus diseases. These morphotypes determine the ease by which A. fumigatus can adapt to stress by antifungal drug exposure, usually resulting in one or more resistance mutations. Key factors that enable the emergence of resistance include genetic variation and selection. The ability to create genetic variation depends on the reproduction mode, including, sexual, parasexual, and asexual, and the population size. These reproduction cycles may take place in the host and/or in the environment, usually when specific conditions are present. Environmental resistance is commonly characterized by tandem repeat (TR)-mediated mutations, while in-host resistance selection results in single-resistance mutations. Reported cases from the literature indicate that environmental resistance mutations are almost exclusively present in patients with IA indicating that the risk for in-host resistance selection is very low. In aspergilloma, single-point mutations are the dominant resistance genotype, while in other chronic Aspergillus diseases, for example, ABPA, CPA, and CF, both TR-mediated and single-resistance mutations are reported. Insights into the pathogenesis of resistance selection in various Aspergillus diseases may help to improve diagnostic and therapeutic strategies.

The molecular structure, biological roles, and inhibition of plant pathogenic fungal chitin deacetylases.

Chitin/polysaccharide deacetylases belong to the carbohydrate esterases family 4 (CE4 enzymes). They play a crucial role in modifying the physiochemical characteristics of structural polysaccharides and are also involved in a wide range of biological processes such as fungal autolysis, spore formation, cell wall formation and integrity, and germling adhesion. These enzymes are mostly common in fungi, marine bacteria, and a limited number of insects. They facilitate the deacetylation of chitin which is a structural biopolymer that is abundantly found in fungal cell walls and spores and also in the cuticle and peritrophic matrices of insects. The deacetylases exhibit specificity towards a substrate containing a sequence of four GlcNAc units, with one of these units being subjected to deacetylation. Chitin deacetylation results in the formation of chitosan, which is a poor substrate for host plant chitinases, therefore it can suppress the host immune response triggered by fungal pathogens and enhance pathogen virulence and colonization. This review discusses plant pathogenic fungal chitin/polysaccharide deacetylases including their structure, substrate specificity, biological roles and some recently discovered chitin deacetylase inhibitors that can help to mitigate plant fungal diseases. This review provides fundamental knowledge that will undoubtedly lead to the rational design of novel inhibitors that target pathogenic fungal chitin deacetylases, which will also aid in the management of plant diseases, thereby safeguarding global food security.

Essential oils from Cuminum cyminum and Laurus nobilis and their principal constituents: evaluation of antifungal and antimycotoxigenic potential in Aspergillus species.

The antifungal and antimycotoxigenic activities of the essential oils (EO) from Cuminum cyminum and Laurus nobilis, and their respective principal compounds, cuminaldehyde and 1,8-cineole, were evaluated against fungi of the genus Aspergillus: A. carbonarius, A. niger, A. ochraceus, and A. westerdijkiae. The antifungal activity was determined by the contact method and the mycelial growth of the fungi was evaluated. Scanning electron microscopic (SEM) images were obtained to suggest modes of action of the compounds analysed. The antimycotoxigenic activity was determined by high-performance liquid chromatograph. Aspergillus carbonarius was completely inhibited by cumin EO (500µl l-1), by laurel EO and by cuminaldehyde (5000µl l-1). The cumin EO (500µl l-1) completely inhibited the growth of A. niger. All the samples inhibited the mycelial growth of A. ochraceus, especially cumin EO and cuminaldehyde (250µl l-1). Aspergillus westerdijkiae was completely inhibited by cumin EO and cuminaldehyde (1000µl l-1), by laurel EO and 1,8-cineole (10 000µl l-1). A decrease in the production of ochratoxin A (OTA) was observed post-treatment, except in A. ochraceus, only inhibited by laurel EO. SEM images showed morphological changes in fungal structures and spore inhibition post-treatment. The results confirmed the antifungal and antimycotoxigenic effect of EO and their principal constituents on fungi evaluated.

Deazaflavin metabolite produced by endosymbiotic bacteria controls fungal host reproduction.

The endosymbiosis between the pathogenic fungus Rhizopus microsporus and the toxin-producing bacterium Mycetohabitans rhizoxinica represents a unique example of host control by an endosymbiont. Fungal sporulation strictly depends on the presence of endosymbionts as well as bacterially produced secondary metabolites. However, an influence of primary metabolites on host control remained unexplored. Recently, we discovered that M. rhizoxinica produces FO and 3PG-F420, a derivative of the specialized redox cofactor F420. Whether FO/3PG-F420 plays a role in the symbiosis has yet to be investigated. Here, we report that FO, the precursor of 3PG-F420, is essential to the establishment of a stable symbiosis. Bioinformatic analysis revealed that the genetic inventory to produce cofactor 3PG-F420 is conserved in the genomes of eight endofungal Mycetohabitans strains. By developing a CRISPR/Cas-assisted base editing strategy for M. rhizoxinica, we generated mutant strains deficient in 3PG-F420 (M. rhizoxinica ΔcofC) and in both FO and 3PG-F420 (M. rhizoxinica ΔfbiC). Co-culture experiments demonstrated that the sporulating phenotype of apo-symbiotic R. microsporus is maintained upon reinfection with wild-type M. rhizoxinica or M. rhizoxinica ΔcofC. In contrast, R. microsporus is unable to sporulate when co-cultivated with M. rhizoxinica ΔfbiC, even though the fungus was observed by super-resolution fluorescence microscopy to be successfully colonized. Genetic and chemical complementation of the FO deficiency of M. rhizoxinica ΔfbiC led to restoration of fungal sporulation, signifying that FO is indispensable for establishing a functional symbiosis. Even though FO is known for its light-harvesting properties, our data illustrate an important role of FO in inter-kingdom communication.

Biological Control of Ustilaginoidea virens Using Chelerythrine Suspension

Background High efficiency, low toxicity, and environmentally safe pesticides are increasingly being sought and developed to ensure sustainable development and high-yield agricultural production. Chelerythrine has strong inhibitory effects against the mycelial growth of crop pathogens such as Fusarium oxysporum, Anthrax, and grey mold. Our previous studies have shown that chelerythrine inhibits fungus spore germination by up to 86.7% and induces the apoptosis of Ustilaginoidea virens cells. The application of chelerythrine as a green biological pesticide would not only enhance agricultural production but also enhance ecological protection. Materials and Methods The formulation of a chelerythrine suspension concentrate was selected. According to the ratio of experimental design requirements to preparation sample, six groups were set up in the field assay; the first spraying was performed approximately 7 days before the rice rupture period, and the second spraying was performed after 10 days. The control effect was investigated at the milk-ripe stage. The present study preliminarily investigates the safety of chelerythrine as a pesticide using the oral acute toxicity test for mice. Results In the present study, the effect of chelerythrine as the main ingredient in suspension concentrate formulations and its field effect on rice false smut (RFS) was investigated. The pesticide in the suspending agent was sprayed twice and had superior effects with regard to the prevention and control of RFS in the field. The control effect was 95.88% at an application rate of 192 mL/ha, with low residue, environmentally safe, and low resistance characteristics. An acute toxicity test following intragastric administration in mice showed that the LD50 of chelerythrine suspension was 1580 mg·kg−1, which was much lower than those of other low-toxicity commercial pesticides. Conclusion Chelerythrine suspension was a low-toxicity agent and exhibited the characteristics of an environmentally friendly plant pesticide. The application of chelerythrine suspension could facilitate the achievement of the goal of pesticide reduction efficiency.

Особенности концентраций аэроаллергенов в городах и влияние на них температуры воздуха

Aim: to examine the content of plant pollen and fungal spores in the air of Karakol city (Kyrgyz Republic) during the seasons from 2015 to 2017. Materials and Methods: in the course of the aerobiological study, samples containing bioparticles (plant pollen and fungal spores) were collected from the air. The samples were identified to the genus or family level, or, in some cases, to the species level, and quantified by visual counting in the field of view of a microscope. A Lanzoni volumetric pollen and spore trap was placed on the roof of a building within the city borders (Karakol) at a height of 13 m above ground level, away from park areas and industrial enterprises. A total of 630 atmospheric air samples were collected from April to September in 2015-2017. Results: the taxa Artemisia spp., Poaceae, Chenopodiaceae, and Pinus spp. exhibited the greatest abundance in the aerobiological spectrum of Karakol. Among the fungi, Alternaria, Cladosporium, and Fusarium were the most prevalent. The majority of fungal spores (60–76%) were observed during the period from June to August. The absolute maximum of pollen in the air coincided with high temperature values in the area. The highest concentrations of Artemisia pollen were observed from mid to late July, which corresponded to an increase in the average daily air temperature over the study seasons. The highest Artemisia pollen content in the air (61–72%) for the study seasons was observed in Karakol at air temperatures ranging from 28.3 to 33.4°C. High temperatures contribute to the release of spores into the atmosphere. It can be observed that allergenic species of fungi are accumulated in urban environments rather than in natural areas. Conclusion: the quantitative and qualitative profile of pollen from the dominant species of allergenic plants and fungal spores in the air environment of Karakol city was determined in order to contribute to the study of the aerobiological situation. It is important to determine the impact of meteorological factors on the concentration of plant pollen and fungal spores. This will allow for the prediction of the behavior of aeroallergens in a changing climate. KEYWORDS: plant pollen, fungal spores, aerobiological monitoring, climate change, air temperature, biological air particles, aeroallergens. FOR CITATION: Osmonbaeva K.B., Churyukina E.V., Dzhambekova G.S., Nazarova E.V. Aeroallergen concentrations in urban areas and the effect of air temperature. Russian Medical Inquiry. 2024;8(3):124–131 (in Russ.). DOI: 10.32364/2587-6821-2024-8-3-2.

Optical measurement instrument for detection of powdery mildew and grey mould in protected crops

This study presents an initiative aimed at developing a real-time optical measurement system for non-contact measurement of airborne fungal spores in protected crops such as strawberries, tomatoes, and cucumbers. The system is based on a customized microscope and an automatic system for trapping fungal spores. It has been tested in the field under real conditions, and image processing algorithms have been developed to identify fungal spores in high-resolution microscope images.

Wpływ krzemu na rozwój i zarodnikowanie grzybów entomopatogenicznych

Silicon is used in the cultivation of agricultural plants as an element that has a positive effect on the development of plants and increases their resistance to stress. It supports the plant’s defense systems, protecting against the penetration of pathogens. Increased silicon content in the environment may have a negative impact on other soil organisms. The aim of the experiment was to demonstrate the ef­fect of using a silicon preparation in various doses on the development of entomopathogenic fungi of the genera Beauveria, Cordyceps and Metarhizium on artificial media. A varied effect of the silicon preparation on the development of fungi have been demonstrated. It was found that at a low dose, the preparation had a positive effect on the production of spores in fungi of the genera Beauveria sp. and Cordyceps sp. In the case of Metarhizium sp., a positive effect on the growth of mycelium was demonstrated, with a simultaneous strong limiting effect of silicon on spore formation.