New Biosensor for Determination of Neuropilin-1 with Detection by Surface Plasmon Resonance Imaging.

Neuropilin-1 is transmembrane protein with soluble isoforms. It plays a pivotal role in both physiological and pathological processes. NRP-1 is involved in the immune response, formation of neuronal circuits, angiogenesis, survival and migration of cells. The specific SPRI biosensor for the determination of neuropilin-1 was constructed using mouse monoclonal antibody that captures unbound NRP-1 form body fluids. The biosensor exhibits linearity of the analytical signal between 0.01 and 2.5 ng/mL, average precision value 4.7% and recovery between 97% and 104%. The detection limit is 0.011 ng/mL, and the limit of quantification is 0.038 ng/mL. The biosensor was validated by parallel determination of NRP-1 in serum and saliva samples using the ELISA test, with good agreement of the results.

An Array SPRi Biosensor for the Determination of Follicle-Stimulating Hormone in Blood Plasma.

Follicle-stimulating hormone (FSH) regulates the development, growth, pubertal maturation and reproductive processes of the human body. The determination of serous FSH concentration is significant as an alternative to testicular biopsy in the case of boys suffering from cryptorchidism after orchidopexy, and as a means of determining the menopausal stage in women. The aim of this investigation is to develop a specific array surface plasmon resonance imaging (SPRi) biosensor for the determination of FSH in body liquids such as blood plasma, obtaining sufficient sensitivity to determine FSH at levels characteristic for that hormone in blood plasma, without any signal enhancement. The biosensor consists of a mouse monoclonal anti-FSH antibody attached to the gold surface of a chip via a cysteamine linker. Its linear response range is from 0.08 mIU mL-1 (LOQ) to 20 mIU mL-1, and well covers most of the range of FSH activities found in blood without dilution. The precision of measurement is between 3.2% and 13.1% for model samples, and between 3.7% and 5.6% for spiked plasma samples. Recoveries are in the range from 94% to 108%. The biosensor has good selectivity, and is validated by comparison with ECLE, with good agreement of the results.

Field assessment of organic amendments and spring barley to phytomanage a Cu/PAH-contaminated soil.

The INTENSE project, supported by the EU Era-Net Facce Surplus, aimed at increasing crop production on marginal land, including those with contaminated soils. A field trial was set up at a former wood preservation site to phytomanage a Cu/PAH-contaminated sandy soil. The novelty was to assess the influence of five organic amendments differing in their composition and production process, i.e. solid fractions before and after biodigestion of pig manure, compost and compost pellets (produced from spent mushroom substrate, biogas digestate and straw), and greenwaste compost, on Cu availability, soil properties, nutrient supply, and plant growth. Organic amendments were incorporated into the soil at 2.3% and 5% soil w/w. Total soil Cu varied from 179 to 1520 mg kg-1, and 1 M NH4NO3-extractable soil Cu ranged from 4.7 to 104 mg kg-1 across the 25 plots. Spring barley (Hordeum vulgare cv. Ella) was cultivated in plots. Changes in physico-chemical soil properties, shoot DW yield, shoot ionome, and shoot Cu uptake depending on extractable soil Cu and the soil treatments are reported. Shoot Cu concentration varied from 45 ± 24 to 140 ± 193 mg kg DW-1 and generally increased with extractable soil Cu. Shoot DW yield, shoot Cu concentration, and shoot Cu uptake of barley plants did not significantly differ across the soil treatments in year 1. Based on soil and plant parameters, the effects of the compost and pig manure treatments were globally discriminated from those of the untreated, greenwaste compost and digested pig manure treatments. Compost and its pellets at the 5% addition rate promoted soil functions related to primary production, water purification, and soil fertility, and the soil quality index.

Seroprevalance of anti-SARS-CoV-2 antibodies in the IgG class in hospitalized children in the north-eastern part of Poland in 2021.

Introduction: In children, SARS-CoV-2 infection may manifest with symptoms of fever, cough, muscle pain, diarrhea or waste smell and taste. However, in most cases it is mild or asymptomatic. Determination of the level of anti-SARS CoV-2 IgG antibodies in children enables to assess retrospectively the incidence of the SARS-CoV-2 infection among children. Aim of the study: The aim of the research was to analyze the results of anti-SARS-CoV-2 antibodies in the IgG class contained in children hospitalized in north-eastern Poland in 2021. Material and methods: The material for the study was venous blood collected once from children hospitalized in Children's University Hospital in Bialystok in 2021. The results obtained from 615 children aged from 1 month to 11 years were analyzed. Determination of the level of antibodies was performed using the automated SARS-COV-2 IgG II test on the VIDAS® analyzer. Results: The analysis of the results of the anti-SARS-CoV-2 IgG value showed that half of children (52%, n=319) had contact with SARS-CoV-2 virus of which approximately 15% (n=47) had documented infection with this virus. There was no difference in the frequency of infections among boys and girls, antibodies were detected in 51% and 53%, respectively. The highest percentage of positive results was observed in children aged 7 to 10 years, 62% (91/147). The least children with a positive result were in the group below 1 year of age, 24% (4/17). High values of the antibody index (>15.00) were most often found among younger children, aged 1-2 years. Conclusions: The presented results showed that infection with the SARS-CoV-2 virus does not depend on the sex of children but the value of anti-SARS-CoV-2 IgG antibodies decreased with the age of the child.

Long-lasting severe knee pain in a SLE patient after renal transplantation: what is the reason? A case report and literature review.

Musculo-skeletal complaints in a patient suffering from systemic lupus, with co-existing chronic renal failure, undergoing immunosuppressive treatment after kidney transplantation, can have a varied etiology. The aim of this work was to present a case based review of differential diagnosis of knee pain in such a patient. A literature search was carried out using MEDLINE/PubMed, Google Scholar and EBSCO, with no time limit. We undertook a systematic review of the literature published in English, limited to full-text publications of original articles, letters to the editor, and case reports in peer-reviewed journals, for a discussion and analysis of studies reporting arthralgia in patients with lupus after kidney transplantation. We present a case report of a 45-year-old woman with lupus nephritis, after kidney transplantation, who started to complain of increasing pain in the knees, most pronounced at night and after physical activity approximately 2 years after transplantation. Extensive causal diagnostics were carried out, which revealed bilateral extensive regions of bone infarction in the femur and tibia, chondropathy, degenerative changes of medial meniscuses in the body and posterior horn as well as chondromalacia of the patella. Establishing the right diagnosis is crucial for implementing appropriate treatment.

An Immunosensor for the Determination of Cortisol in Serum and Saliva by Array SPRi.

Cortisol is a hormone which plays an essential role in the immune, endocrine, cardiovascular, renal and skeletal systems. Its level increases in response to stress, illness, injury or exhaustion, and it is therefore a significant diagnostic biomarker of stress. An immunosensor for the determination of cortisol by SPRi array was developed. The receptive part of the immunosensor is mouse monoclonal antibody against cortisol, immobilized via cysteamine linker. The optimum pH of the immunosensor is 7.4, and the optimum concentration of the antibody is 50 ng mL-1. The immunosensor is specific for cortisol, and its linear response ranges from 0.20 ng mL-1 (LOQ) to 8 ng mL-1. The precision of the determination was between 3.1% and 3.3%, and the recovery between 99% and 102%. The immunosensor was validated by simultaneous determination of cortisol in serum and saliva samples by a standard method, with good agreement between the results.

Two Biosensors for the Determination of VEGF-R2 in Plasma by Array SPRi.

Vascular endothelial growth factor receptor 2 (VEGF-R2) is a marker of angiogenesis and metastasis of cancer. Two biosensors for the determination of VEGF-R2 in plasma have been developed. One of them is based on a pure gold chip, and the other on a silver/gold bimetallic chip; both have the receptor, monoclonal rabbit antibody specific for human VEGF-R2, attached to the chip via a cysteamine linker. The biosensor with the gold chip exhibits linearity of the analytical signal between 0.03 and 2 ng/mL, a precision of 1.4% and recovery between 99% and 102%. The biosensor with the bimetallic chip exhibits linearity between 0.03 and 1 ng/mL, a precision of 2.2% and recovery between 99% and 103%. Both biosensors tolerate a 1:100 excess of VEGF, VEGF-R1 and VEGF-R3. Both biosensors were validated by parallel determination of VEGF-R2 in 27 different plasma samples using the ELISA immunosensor assay, with very good agreement of the results. Thermodynamic parameters of the interaction of VEGF-R2 with the antibody were determined by QCM (Quartz Crystal Microbalance) and SPRi (Surface Plasmon Resonance imaging) measurements.

Influence of the catchment area use on the water quality in the Utrata River.

The present paper discusses the impact of land use and seasons on the concentration of nutrients in the waters of the Utrata River (Pruszków Poviat, Mazowieckie Voivodeship) from April 2018 to March 2019. The pollution of rivers by nutrients is a major problem for society. Surface water is a source of drinking water, water used for industrial and agricultural purposes. With the increasing pollution of rivers, the purification process for these purposes becomes more expensive and more challenging. To assist in carrying out activities aimed at reducing the inflow of biogenic substances into large river systems and then down to the Baltic Sea, we analyzed the spatial and temporal dynamics of loads from the entire Utrata River catchment area. We divided the entire catchment area into three impact zones: grasslands and wastelands, urbanized areas, and agricultural land and examined changes in nutrient concentrations (total phosphorus, nitrate nitrogen, ammonium nitrogen) in each of the zones. The results were statistically processed using the 1-factor ANOVA method with the p-value of significance below 0.05. Research indicates an increase in the concentration of total phosphorus and nitrogen forms down the course of the river in urban and agricultural areas with persistently low concentrations of these biogenic substances in grasslands.

Comparison of the interleukin 27 expression for the acute and chronic phase of mononucleosis in children.

BACKGROUND: The objective of the current study was to assess the serum level of interleukin 27 in children with mononucleosis and to compare the expression of this cytokine in the acute and chronic phase of the infection. METHODS: The level of IL-27 was determined using commercial enzyme-linked immunosorbent assay (ELISA) kits (Diaclone SAS, Besancon, France). Other laboratory findings were determined using routine laboratory methods. RESULTS: Serum level of IL-27 was found to be significantly higher in children with mononucleosis in comparison with healthy subjects (almost a 4-fold increase, 15.7 vs. 4.2 pg/mL, p < 0.001). It was also significantly higher in the acute phase compared to the chronic stage of the disease (more than a two-fold increase, 20.7 vs. 9.64 pg/mL, p < 0.001). This cytokine positively correlated with ALT, AST, LDH activity and WBC count (R = 0.498, p < 0.001; R = 0.586, p < 0.001; R = 0.170, p < 0.05, R = 0.329, p < 0.05, respectively) in the whole study, and only with AST activity in the chronic phase subgroup (R = 0.684, p < 0.05). CONCLUSION: In conclusion, this study shows that serum concentration of interleukin 27 in children with mononucleosis is increased, thus confirming the on-going inflammatory process. We also suggest that IL-27 can be a useful indicator to differentiate between the acute and chronic phase of the disease.

An SPRi Biosensor for Determination of the Ovarian Cancer Marker HE4 in Human Plasma.

Human epididymis protein 4 (HE4) is an ovarian cancer marker. Various cut-off values of the marker in blood are recommended, depending on the method used for its determination. An alternative biosensor for HE4 determination in blood plasma has been developed. It consists of rabbit polyclonal antibody against HE4, covalently attached to a gold chip via cysteamine linker. The biosensor is used with the non-fluidic array SPRi technique. The linear range of the analytical signal response was found to be 2-120 pM, and the biosensor can be used for the determination of the HE4 marker in the plasma of both healthy subjects and ovarian cancer patients after suitable dilution with a PBS buffer. Precision (6-10%) and recovery (101.8-103.5%) were found to be acceptable, and the LOD was equal to 2 pM. The biosensor was validated by the parallel determination of a series of plasma samples from ovarian cancer patients using the Elecsys HE4 test and the developed biosensor, with a good agreement of the results (a Pearson coefficient of 0.989). An example of the diagnostic application of the developed biosensor is given-the influence of ovarian tumor resection on the level of HE4 in blood serum.

The influence of a dam reservoir on water quality in a small lowland river.

The paper presents the effects of the dam reservoir in Komorów on the water quality in the Utrata river. The implementation of the adopted objective involved a comparison of water quality at two points, above and below the reservoir. The Utrata River is polluted with biogenic compounds throughout the whole section studied. COD content also indicates significant contamination exceeding permissible limits. A positive effect of the reservoir on water quality in the river was also observed in terms of the content of dissolved oxygen, with concentration increasing below the reservoir. The reservoir had a positive effect on reducing the concentration of total phosphorus in the water. Water in the Utrata below the reservoir showed higher values of chemical oxygen demand (CODMn) than above the reservoir. There were no differences in the concentration of NH4+ and NO3- ions in the water before and after the reservoir.

Vascular endothelial growth factor and transforming growth factor ß in hypertrophic adenoids in children suffering from otitis media with effusion.

OBJECTIVES: The study objective was to assess the levels of VEGF-A and TGF-ß cytokines in the children with adenoid hypertrophy concomitant with exudative otitis media (OME) and in children with adenoid hypertrophy (HA) alone. METHODS: The study material consisted of hypertrophic adenoids removed during adenoidectomy from 39 children (20 girls and 19 boys), aged 2-7 years suffering from OME. The reference group included 41 children (19 girls and 22 boys), aged from 3 to 9 years with adenoid hypertrophy. The levels of VEGF-A and TGF-ß were determined in supernatants obtained from phytohemagglutinin-stimulated cell cultures of the adenoids using a commercial enzyme-linked immunosorbent assay kit. RESULTS: The median VEGF-A and mean TGF-ß concentrations in the study group were significantly higher than those in the reference group (503 pg/mL versus 201 pg/mL, P < 0.001 and 224 pg/mL versus 132 pg/mL, P < 0.001, respectively). ROC analysis revealed that the area under the curve (AUC) for VEGF-A was 0.952 with diagnostic sensitivity and specificity of 95%, whereas for TGF-ß it was 0.902 with 60% sensitivity and the same specificity as for VEGF-A. There was no significant difference between the AUC for VEGF-A and TGF-ß (P = 0.573). CONCLUSIONS: The changes in the levels of VEGF-A and TGF-ß may indicate bacterial pathogen as one of the causes of exudative otitis media in children. Determination of VEGF-A and TGF-ß could be used as additional and objective tests to confirm the clinical diagnosis.

The influence of different intensity of treatment on hormonal markers of gonadal function in acute lymphoblastic leukemia survivors.

Anti-cancer treatment in children can deteriorate gonadal function and affect future fertility. We analyzed the hormonal markers of gonadal function in adolescent leukemia survivors, treated in childhood with different levels of aggressiveness. We analyzed hormone levels in 69 adolescents and young adults, leukemia survivors stratified into standard (SR), intermediate (IR), and high (HR) risk groups, and in 80 healthy controls (38 men) at a similar age. We assessed follicular stimulating hormone (FSH), luteinizing hormone (LH), and inhibin B in the whole group, testosterone in males, and E2 and anti-Müllerian hormone (AMH) in females. Males classified into HR group presented, in comparison to control, higher levels of FSH, LH, lower inhibin B, and normal testosterone, whereas in SR and IR group, the hormonal values were comparable to the control. In females, in all risk groups, the levels of FSH, LH, E2, and inhibin B were comparable with the control, but the mean AMH levels were slightly lowered. We did not observe the effect of prophylactic cranial irradiation (12 or 18 Gy) or the time of treatment (before vs. during puberty) on hormone levels. In females, a positive correlation was found between the time interval after the end of treatment and AMH levels. Male leukemia survivors having undergone more intensive chemotherapy show the symptoms of disturbed spermatogenesis and need to be followed-up in the future. Women, irrespective of the risk group, can develop the signs of preterm ovarian insufficiency. They should be informed about the impact of the treatment on gonadal function.

Use of the Sysmex XT-4000i hematology analyzer in the differentiation of cerebrospinal fluid cells in children.

BACKGROUND: Routine analysis of pleocytosis and cellular composition of cerebrospinal fluid (CSF) is carried out with a phase-contrast microscope. The use of hematological analyzers seems to be an alternative to the manual method. The aim of the study was to assess the usefulness of the automated technique for counting and differentiating CSF cells in children. METHODS: The study group consisted of 59 children (28 girls and 31 boys) aged from 4 to 17 years suffering from viral and bacterial meningitis. Children were divided into three subgroups according to CSF cell count: 1st group had a pleocytosis of 6-50 cells/µL, 2nd group-51-100 cells/µL, and 3rd group->100 cells/µL. A reference group involved 32 children (17 girls and 15 boys) aged from 2 to 18 years with a normal range of 0-5 cells/µL. Examination of CSF was performed in parallel by two different method, manual and automated. RESULTS: The analysis of pleocytosis revealed that the values obtained by the manual method were statistically significantly lower in relation to the values obtained by automated technique in subgroups I and II. The number of mononuclear and polymorphonuclear cells in subgroups I, II, and III determined by both manual and automated methods was comparable. CONCLUSION: We conclude that automated method cannot fully replace the previously used manual method and some of the dubious cases, such as samples with low pleocytosis rates or abnormal cells indicated by the analyzer, will still require microscopic examination.

Diagnostic Usefulness of Insulin-Like Growth Factor 1 and Insulin-Like Growth Factor Binding Protein 3 in Children with Suspected Pituitary Dwarfism.

BACKGROUND: Pituitary dwarfism (also known as short stature) is a medical condition in which the pituitary gland does not produce enough growth hormone (GH). To confirm the diagnosis of growth hormone deficiency the overnight profile of GH secretion and GH provocative tests are usually performed; however, due to wide GH fluctuations throughout the day and night and the invasiveness of stimulation tests, their clinical utility is limited. Therefore, screening for IGF-1 (insulin-like growth factor 1) and IGFBP-3 (insulin-like growth factor binding protein type 3) is proposed, suggesting that these tests provide a more accurate reflection of the mean plasma GH level, although the results of these tests are still problematic. In this context, the aim of this study was to assess the diagnostic usefulness of IGF-1 and IGFBP-3 in children with suspected pituitary dwarfism. METHODS: Studies were carried out in 127 children with abnormal growth and low spontaneous 24-hour plasma GH profiles and abnormal results of GH stimulation tests. Fasting serum IGF-1 and IGFBP-3 were determined by chemiluminescent quantitative measurement using the IMMULITE 1000 IGF-1 and IGFBP-3 kits (Siemens Healthcare Diagnostics, United Kingdom) on the IMMULITE 1000 analyzer (Siemens Healthcare Diagnostics, USA). Results were compared to the normal range by children's age. RESULTS: Mean serum IGF-1 concentrations were within the lower normal range (41.7% cases), and 58.3% results were below the normal reference range in the study group. The average serum IGFBP-3 levels were within the lower normal range. CONCLUSIONS: We conclude that IGF-1 test can be a useful tool in the diagnosis of pituitary dwarfism in children suspected of this condition, but due to relatively poor sensitivity the testing cannot be performed alone, but in combination with other tests. The IGFBP-3 test is not useful for the diagnosis of this disease.

Comparison of the Diagnostic Power of Serum IL-6, IL-8 and TNF-α for the Idiopathic Anterior Uveitis in Children.

BACKGROUND: Uveitis is the inflammation of the uvea that often occurs in children. There are many causes of disease, but some of them do not have any reasons and are then called idiopathic uveitis. Cytokines play an important role in the regulation of the immune response. Determination of cytokine profiles could contribute to the explanation of the etiology of uveitis and could serve to evaluate the inflammation intensity as well as be helpful in the early diagnosis this disease. The purpose of this study was to determine the serum level of selected inflammatory cytokines, such as interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor α (TNF-α) and to compare their diagnostic power as a markers of idiopathic anterior uveitis in children. METHODS: The study was carried out on 28 children diagnosed with idiopathic anterior uveitis. The reference group comprised 30 healthy children. Serum IL-6, IL-8, and TNF-α concentrations were measured with specific enzyme-linked immunoassay (ELISA) methods. RESULTS: The mean values of IL-6, IL-8, and TNF-α in the children with idiopathic anterior uveitis were significantly higher than those found in the reference group. The highest sensitivity, specificity, accuracy, positive and negative predictive value, and likelihood ratio of a positive test result were achieved for IL-8. There was a significant difference between the area under the curve for IL-6 and IL-8. CONCLUSIONS: Increased serum concentrations of interleukin IL-6, IL-8, and TNF-α may suggest that these cytokines induce inflammatory changes in the ocular surface. Analysis of cytokine levels showed that IL-8 has the highest diagnostic power and is the best marker for diagnosis of idiopathic anterior uveitis in children.

[Vitamin D deficiency in psoriatic patients in north-east of Poland].

Background: Recent studies point out the important role of vitamin D in the pathogenesis of many autoimmune diseases, in between psoriasis. Vitamin D regulates function of the dendritic cells, proliferation and maturation of the keratynocytes and lymphocytes T. The aim of the study was to evaluate serum vitamin D (25OHD) concentrations in psoriatic patients in the north-east of Poland and their comparison in the summer and winter period of the year. We also evaluated relationship between 25OHD concentration and disease severity, prevalence of psoriatic comorbidities and laboratory results. Material and Methods: 25OHD serum concentration was evaluated by electrochemiluminescent method in 115 patients with exacerbated plaque type psoriasis. 39 patients were evaluated in the summer and 79 in the winter time. 28 patients from winter group were treated with narrow band ultraviolet B radiation (NB-UVB). The results were compared with 38 healthy persons. Results: 25OHD serum concentrations of psoriatic patients were significantly lower than in the control group (p=0,0003). Vitamin D deficiency was diagnosed in 66% of patients in the summer time and in 63% in winter time; in the control group: 24% during the summer and 71% during the winter. After UVB phototherapy we observed reduction of skin lesions, measured as a significant decline in the Psoriasis Area and Severity Index (PASI) (p<0.001). The serum 25OHD concentration increased (p<0.001). After the treatment 65% of the psoriatic patients reached normal range of 25OHD concentration, 35% of patients were still vitamin D insufficient. We demonstrate positive correlation between increase in 25OHD and number of NB-UVB phototherapy sessions (r=0.38). Conclusions: We have observed vitamin D deficiency both in psoriatic patients and in the control group. Among psoriatic patients the praevalence of deficiency were higher than in the control group, especially during the summer months. Frequent vitamin D defficiency in the groups studied indicates the need of for its supplementation. The 25OHD serum concentrations increased after phototherapy with UVB.

Frequently asked questions about in vivo chlorophyll fluorescence: practical issues.

The aim of this educational review is to provide practical information on the hardware, methodology, and the hands on application of chlorophyll (Chl) a fluorescence technology. We present the paper in a question and answer format like frequently asked questions. Although nearly all information on the application of Chl a fluorescence can be found in the literature, it is not always easily accessible. This paper is primarily aimed at scientists who have some experience with the application of Chl a fluorescence but are still in the process of discovering what it all means and how it can be used. Topics discussed are (among other things) the kind of information that can be obtained using different fluorescence techniques, the interpretation of Chl a fluorescence signals, specific applications of these techniques, and practical advice on different subjects, such as on the length of dark adaptation before measurement of the Chl a fluorescence transient. The paper also provides the physiological background for some of the applied procedures. It also serves as a source of reference for experienced scientists.

Differences between Tuberous Sclerosis Complex Patients with and without Epilepsy: The Results of a Quantitative Diffusion Tensor Imaging Study.

INTRODUCTION: Tuberous sclerosis complex (TSC) is a neurocutaneous disease with a high incidence of epilepsy and damaging effects on cognitive development. To understand the mechanisms leading to abnormal cognitive development, diffusion tensor imaging (DTI) techniques have begun to be used in recent years. The present study is the first to investigate differences in the microstructure and integrity of white matter tracts in adult patients with TSC and with and without epilepsy. METHOD: A total of 37 patients with TSC (18 with epilepsy, median age 36 years; 19 without epilepsy, median age 35 years) without intellectual disability and autism spectrum disorder were included in the study. The control group (median age 34 years) comprised 37 individuals without psychiatric or neurodevelopmental disorders and neurological and cardiovascular diseases, diabetes, or addictions. A magnetic resonance imaging (MRI) DTI sequence was applied. RESULTS: There were differences in the average values of DTI parameters between patients with TSC and epilepsy and patients with TSC but without epilepsy in five white matter bands. When comparing the average values of DTI parameters between patients with TSC and epilepsy and healthy controls, we found differences in 15 of 20 analysed white matter fibres. White matter tracts in patients with TSC and epilepsy had more abnormalities than in patients with TSC but without epilepsy. The former group presented abnormalities in longer white matter fibres, especially in the left hemisphere. However, the latter group presented abnormalities in more medial and shorter white matter fibres. CONCLUSION: This DTI study documents the changes in the brain white matter of patients with TSC associated with the presence of epilepsy.

Silicon Modifies Photosynthesis Efficiency and hsp Gene Expression in European Beech (Fagus sylvatica) Seedlings Exposed to Drought Stress.

Background: Climate change is leading to severe and long-term droughts in European forest ecosystems. can have profound effects on various physiological processes, including photosynthesis, gene expression patterns, and nutrient uptake at the developmental stage of young trees. Objectives: Our study aimed to test the hypothesis that the application of silica (SiO2) influences photosynthetic efficiency and gene expression in 1- to 2-year-old Fagus sylvatica (L.) seedlings. Additionally, we aimed to assess whether silicon application positively influences the structural properties of leaves and roots. To determine whether the plant physiological responses are genotype-specific, seedlings of four geographically different provenances were subjected to a one-year evaluation under greenhouse conditions. Methods: We used the Kruskal-Wallis test followed by Wilcoxon's test to evaluate the differences in silicon content and ANOVA followed by Tukey's test to evaluate the physiological responses of seedlings depending on treatment and provenance. Results: Our results showed a significantly higher Si content in the roots compared with the leaves, regardless of provenance and treatment. The most significant differences in photosynthetic performance were found in trees exposed to Si treatment, but the physiological responses were generally nuanced and provenance-dependent. Expression of hsp70 and hsp90 was also increased in leaf tissues of all provenances. These results provide practical insights that Si can improve the overall health and resilience of beech seedlings in nursery and forest ecosystems, with possible differences in the beneficial role of silicon application arising from the large differences in wild populations of forest tree species.