Natural variation and dosage of the HEI10 meiotic E3 ligase control Arabidopsis crossover recombination.

During meiosis, homologous chromosomes undergo crossover recombination, which creates genetic diversity and balances homolog segregation. Despite these critical functions, crossover frequency varies extensively within and between species. Although natural crossover recombination modifier loci have been detected in plants, causal genes have remained elusive. Using natural Arabidopsis thaliana accessions, we identified two major recombination quantitative trait loci (rQTLs) that explain 56.9% of crossover variation in Col×Ler F2 populations. We mapped rQTL1 to semidominant polymorphisms in HEI10, which encodes a conserved ubiquitin E3 ligase that regulates crossovers. Null hei10 mutants are haploinsufficient, and, using genome-wide mapping and immunocytology, we show that transformation of additional HEI10 copies is sufficient to more than double euchromatic crossovers. However, heterochromatic centromeres remained recombination-suppressed. The strongest HEI10-mediated crossover increases occur in subtelomeric euchromatin, which is reminiscent of sex differences in Arabidopsis recombination. Our work reveals that HEI10 naturally limits Arabidopsis crossovers and has the potential to influence the response to selection.

MSH2 shapes the meiotic crossover landscape in relation to interhomolog polymorphism in Arabidopsis.

During meiosis, DNA double-strand breaks undergo interhomolog repair to yield crossovers between homologous chromosomes. To investigate how interhomolog sequence polymorphism affects crossovers, we sequenced multiple recombinant populations of the model plant Arabidopsis thaliana. Crossovers were elevated in the diverse pericentromeric regions, showing a local preference for polymorphic regions. We provide evidence that crossover association with elevated diversity is mediated via the Class I crossover formation pathway, although very high levels of diversity suppress crossovers. Interhomolog polymorphism causes mismatches in recombining molecules, which can be detected by MutS homolog (MSH) mismatch repair protein heterodimers. Therefore, we mapped crossovers in a msh2 mutant, defective in mismatch recognition, using multiple hybrid backgrounds. Although total crossover numbers were unchanged in msh2 mutants, recombination was remodelled from the diverse pericentromeres towards the less-polymorphic sub-telomeric regions. Juxtaposition of megabase heterozygous and homozygous regions causes crossover remodelling towards the heterozygous regions in wild type Arabidopsis, but not in msh2 mutants. Immunostaining showed that MSH2 protein accumulates on meiotic chromosomes during prophase I, consistent with MSH2 regulating meiotic recombination. Our results reveal a pro-crossover role for MSH2 in regions of higher sequence diversity in A. thaliana.

Development of a deep-learning model tailored for HER2 detection in breast cancer to aid pathologists in interpreting HER2-low cases.

AIMS: Over 50% of breast cancer cases are "Human epidermal growth factor receptor 2 (HER2) low breast cancer (BC)", characterized by HER2 immunohistochemistry (IHC) scores of 1+ or 2+ alongside no amplification on fluorescence in situ hybridization (FISH) testing. The development of new anti-HER2 antibody-drug conjugates (ADCs) for treating HER2-low breast cancers illustrates the importance of accurately assessing HER2 status, particularly HER2-low breast cancer. In this study we evaluated the performance of a deep-learning (DL) model for the assessment of HER2, including an assessment of the causes of discordances of HER2-Null between a pathologist and the DL model. We specifically focussed on aligning the DL model rules with the ASCO/CAP guidelines, including stained cells' staining intensity and completeness of membrane staining. METHODS AND RESULTS: We trained a DL model on a multicentric cohort of breast cancer cases with HER2-IHC scores (n = 299). The model was validated on two independent multicentric validation cohorts (n = 369 and n = 92), with all cases reviewed by three senior breast pathologists. All cases underwent a thorough review by three senior breast pathologists, with the ground truth determined by a majority consensus on the final HER2 score among the pathologists. In total, 760 breast cancer cases were utilized throughout the training and validation phases of the study. The model's concordance with the ground truth (ICC = 0.77 [0.68-0.83]; Fisher P = 1.32e-10) is higher than the average agreement among the three senior pathologists (ICC = 0.45 [0.17-0.65]; Fisher P = 2e-3). In the two validation cohorts, the DL model identifies 95% [93% - 98%] and 97% [91% - 100%] of HER2-low and HER2-positive tumours, respectively. Discordant results were characterized by morphological features such as extended fibrosis, a high number of tumour-infiltrating lymphocytes, and necrosis, whilst some artefacts such as nonspecific background cytoplasmic stain in the cytoplasm of tumour cells also cause discrepancy. CONCLUSION: Deep learning can support pathologists' interpretation of difficult HER2-low cases. Morphological variables and some specific artefacts can cause discrepant HER2-scores between the pathologist and the DL model.

Natural variation identifies SNI1, the SMC5/6 component, as a modifier of meiotic crossover in Arabidopsis.

The frequency and distribution of meiotic crossovers are tightly controlled; however, variation in this process can be observed both within and between species. Using crosses of two natural Arabidopsis thaliana accessions, Col and Ler, we mapped a crossover modifier locus to semidominant polymorphisms in SUPPRESSOR OF NPR1-1 INDUCIBLE 1 (SNI1), which encodes a component of the SMC5/6 complex. The sni1 mutant exhibits a modified pattern of recombination across the genome with crossovers elevated in chromosome distal regions but reduced in pericentromeres. Mutations in SNI1 result in reduced crossover interference and can partially restore the fertility of a Class I crossover pathway mutant, which suggests that the protein affects noninterfering crossover repair. Therefore, we tested genetic interactions between SNI1 and both RECQ4 and FANCM DNA helicases, which showed that additional Class II crossovers observed in the sni1 mutant are FANCM independent. Furthermore, genetic analysis of other SMC5/6 mutants confirms the observations of crossover redistribution made for SNI1 The study reveals the importance of the SMC5/6 complex in ensuring the proper progress of meiotic recombination in plants.

The Impact of Proinflammatory Cytokines and Imiquimod on GLUT1 in HaCaT Keratinocytes - a Potential Anti-Psoriatic Therapeutic Target?

BACKGROUND/AIMS: Glucose metabolism has been proven as an essential process for proliferating keratinocytes, which highlights the importance of glucose transporter-1 (GLUT1) not only in the onset of psoriasis but also in the progression and severity of this inflammation-driven disease. In this study, we attempted to find a connection between proinflammatory cytokines (IL-6, IL-17, IL-23, IL-36, TNF-α), a skin inflammation inducing agent - imiquimod (IMQ) and GLUT1 expression. METHODS: Human keratinocyte HaCaT cell line was incubated with exogenous cytokines: IL-6, IL-17A, IL-23, IL-36, TNF-α at a final concentration of 100 ng/ml, or with 1 µM of IMQ, for 48 h. Following the stimulation, glucose uptake and GLUT1 expression were evaluated. The activity of GLUT1 was measured in the presence of a selective GLUT1 inhibitor, BAY-876. The expression of GLUT1 was examined by immunofluorescence and quantified by qPCR, Western blotting and densitometry. RESULTS: The results from qPCR analysis showed that the administration of exogenous IL-6, IL-17, IL-23 and IL-36 to HaCaT cells resulted in upregulation of GLUT1-encoding SLC2A1 gene, while TNF-α had no significant effect. The same results were confirmed by immunofluorescence analysis, as the fluorescent intensity of GLUT1 was elevated following cytokine and IMQ stimulation. Western blot and densitometry showed that all examined cytokines, as well as IMQ, increased GLUT1 expression. HaCaT cells displayed an improved intracellular 2-deoxy-D-glucose (2-DG) uptake and GLUT1 activity after stimulation by exogenous cytokines and IMQ. The highest uptake of 2-DG was observed after IL-23 stimulation (1.93x) and the lowest after TNF-α stimulation (1.07x). BAY-876 inhibited the 2-DG uptake compared to control. CONCLUSION: Our findings suggest that cytokines and IMQ may play a key role in regulating GLUT1 expression in HaCaT cells. We believe that GLUT1 overexpression could potentially be utilized in the targeted treatment of psoriasis.

Breast cancer risk in papilloma patients: Osteopontin splice variants indicate prognosis.

BACKGROUND: Papillomas of the breast pose challenges for treatment decisions as their risk for transformation to breast cancer is low but not negligible. To spare low-risk patients the burden of substantial treatment side effects, prognostic indicators are needed for cancerous progression. The secreted metastasis mediator Osteopontin (OPN) is a marker for breast cancer aggressiveness, and its variants are prognosticators for transformation in diverse premalignant breast lesions. Here, we test whether the presence of OPN-c or OPN-exon-4 in papillomatous lesions may reflect progression risk. METHODS: By immunohistochemistry, we analyze OPN-c and OPN-exon-4 in papillomas from 114 women as well as correlations between staining and progression. In departure from prior spliced OPN biomarker publications, we utilize novel monoclonal antibodies. RESULTS: Fewer than 5% of OPN-c pathology score 0-1 (intensity) versus almost 18% of score 2-3 experienced cancer in follow-up. Nine of 12 women, who progressed, had pathology scores of 2-3 for OPN-c intensity at the time of initial diagnosis, and none had a score of 0. When developing a combined risk score from intensity plus percent positivity for OPN-c, the progression risk for patients with low score was 3.2%, for intermediate score was 5.7%, and for high score was 18.8%. Papillomas in patients, who were later diagnosed with cancer in the contralateral breast, displayed stronger staining positivity than non-progressors. CONCLUSION: OPN splice variant immunohistochemistry on biopsies of breast papillomas will allow counseling of the patients on their risk to develop breast cancer at a later time.

An Update on Photodynamic Therapy of Psoriasis-Current Strategies and Nanotechnology as a Future Perspective.

Psoriasis (PS) is an immune-mediated skin disease with substantial negative effects on patient quality of life. Despite significant progress in the development of novel treatment options over the past few decades, a high percentage of patients with psoriasis remain undertreated and require new medications with superior long-term efficacy and safety. One of the most promising treatment options against psoriatic lesions is a form of phototherapy known as photodynamic therapy (PDT), which involves either the systemic or local application of a cell-targeting photosensitizing compound, followed by selective illumination of the lesion with visible light. However, the effectiveness of clinically incorporated photosensitizers in psoriasis treatment is limited, and adverse effects such as pain or burning sensations are frequently reported. In this study, we performed a literature review and attempted to provide a pooled estimate of the efficacy and short-term safety of targeted PDT in the treatment of psoriasis. Despite some encouraging results, PDT remains clinically underutilized. This highlights the need for further studies that will aim to evaluate the efficacy of a wider spectrum of photosensitizers and the potential of nanotechnology in psoriasis treatment.

The Comparison of the Efficiency of Emodin and Aloe-Emodin in Photodynamic Therapy.

Skin cancer (melanoma and non-melanoma) is the most frequent type of malignancy in the Caucasian population. Photodynamic therapy (PDT) as an interesting and unique strategy may potentially boost standard therapeutic approaches. In the present study, the potential of emodin and aloe-emodin as photosensitizers in photodynamic therapy has been investigated. The conducted research presents for the first-time comparison of the phototoxic and anti-cancerous effects of emodin and aloe-emodin on skin cancer cell lines, including SCC-25 representing cutaneous squamous cell carcinoma, MUG-Mel2 representing a melanoma cell line, and normal human keratinocytes HaCaT representing control normal skin cells. To assess the effectiveness of emodin and aloe-emodin as a photosensitizer in PDT on different skin cell lines, we performed MTT assay measuring cytotoxicity of natural compounds, cellular uptake, apoptosis with flow cytometry, and a wound-healing assay. Although emodin and aloe-emodin are isomers and differ only in the position of one hydroxyl group, our phototoxicity and apoptosis detection results show that both substances affect skin cancer cells (SSC-25 squamous cell carcinoma and MUG-Mel2 melanoma) and normal keratinocytes (HaCaT cell line) in other ways. In conclusion, our study provides evidence suggesting that emodin and aloe-emodin mediated PDT exhibits the potential for clinical development as a new effective and safe photosensitizer to treat skin cancer.

Nucleosomes and DNA methylation shape meiotic DSB frequency in Arabidopsis thaliana transposons and gene regulatory regions.

Meiotic recombination initiates from DNA double-strand breaks (DSBs) generated by SPO11 topoisomerase-like complexes. Meiotic DSB frequency varies extensively along eukaryotic chromosomes, with hotspots controlled by chromatin and DNA sequence. To map meiotic DSBs throughout a plant genome, we purified and sequenced Arabidopsis thaliana SPO11-1-oligonucleotides. SPO11-1-oligos are elevated in gene promoters, terminators, and introns, which is driven by AT-sequence richness that excludes nucleosomes and allows SPO11-1 access. A positive relationship was observed between SPO11-1-oligos and crossovers genome-wide, although fine-scale correlations were weaker. This may reflect the influence of interhomolog polymorphism on crossover formation, downstream from DSB formation. Although H3K4me3 is enriched in proximity to SPO11-1-oligo hotspots at gene 5' ends, H3K4me3 levels do not correlate with DSBs. Repetitive transposons are thought to be recombination silenced during meiosis, to prevent nonallelic interactions and genome instability. Unexpectedly, we found high SPO11-1-oligo levels in nucleosome-depleted Helitron/Pogo/Tc1/Mariner DNA transposons, whereas retrotransposons were coldspots. High SPO11-1-oligo transposons are enriched within gene regulatory regions and in proximity to immunity genes, suggesting a role as recombination enhancers. As transposon mobility in plant genomes is restricted by DNA methylation, we used the met1 DNA methyltransferase mutant to investigate the role of heterochromatin in SPO11-1-oligo distributions. Epigenetic activation of meiotic DSBs in proximity to centromeres and transposons occurred in met1 mutants, coincident with reduced nucleosome occupancy, gain of transcription, and H3K4me3. Together, our work reveals a complex relationship between chromatin and meiotic DSBs within A. thaliana genes and transposons, with significance for the diversity and evolution of plant genomes.

Massive crossover elevation via combination of HEI10 and recq4a recq4b during Arabidopsis meiosis.

During meiosis, homologous chromosomes undergo reciprocal crossovers, which generate genetic diversity and underpin classical crop improvement. Meiotic recombination initiates from DNA double-strand breaks (DSBs), which are processed into single-stranded DNA that can invade a homologous chromosome. The resulting joint molecules can ultimately be resolved as crossovers. In Arabidopsis, competing pathways balance the repair of ∼100-200 meiotic DSBs into ∼10 crossovers per meiosis, with the excess DSBs repaired as noncrossovers. To bias DSB repair toward crossovers, we simultaneously increased dosage of the procrossover E3 ligase gene HEI10 and introduced mutations in the anticrossovers helicase genes RECQ4A and RECQ4B As HEI10 and recq4a recq4b increase interfering and noninterfering crossover pathways, respectively, they combine additively to yield a massive meiotic recombination increase. Interestingly, we also show that increased HEI10 dosage increases crossover coincidence, which indicates an effect on interference. We also show that patterns of interhomolog polymorphism and heterochromatin drive recombination increases distally towards the subtelomeres in both HEI10 and recq4a recq4b backgrounds, while the centromeres remain crossover suppressed. These results provide a genetic framework for engineering meiotic recombination landscapes in plant genomes.

Trends in glioblastoma treatment research: an analysis of clinical trials and literature.

INTRODUCTION: Glioblastoma is the most common, and the most lethal, primary malignant brain tumour in adults. The aim of the study was to present a comprehensive, data-based review of glioblastoma treatment research, considering all clinical trials and peer-reviewed journal publications. MATERIALS AND METHODS: Data regarding all glioblastoma clinical trials that was available on 7 August 2019 on ClinicalTrials.gov was analysed. Information on interventions' mechanisms of action was obtained from AdisInsight. A PubMed search for 'glioblastoma' was performed in September 2019. Citation counts were gathered from Scopus. Custom software for obtaining and analyzing data was developed by the authors. RESULTS: 1,388 clinical trials on glioblastoma with a start date between 1979 and 2020 were identified. The distribution of glioblastoma clinical trial phases differs significantly from that of other high-mortality cancers. 526 unique interventions of clinical trials and 206 molecular targets have been isolated. 32,410 publications on glioblastoma have been found, the number having increased especially since 2006. Publications on identified treatment options comprised 32.2%. Publications on glioblastoma are cited on average 4.27 times per year. The average specificity of treatment options' publications for glioblastoma is 6.9%. CONCLUSIONS: Glioblastoma treatment options and their molecular targets can be quantitatively ranked according to their scientific research output. To the best of our knowledge, no such registries have been elaborated before.

The role of MutS complex and MSH2 protein in the crossover control in plants / Rola kompleksu MutS oraz bialka MSH2 w kontroli crossing-over u roslin.

Crossover is a reciprocal exchange of chromatid fragments between homologous chromosomes and takes place during second meiotic division. Many factors affect the distribution and frequency of crossovers ­ for instance, the activity of trans-acting modifiers, chromatin methylation level or the presence of polymorphisms between recombining chromosomes. MMR system, and specifically MSH2 protein, serves to recognize and repair mismatched DNA bases, and prevents recombination between divergent chromosomal regions during meiosis. Unexpectedly, MSH2 displays also a pro-recombination role in plants by detecting polymorphisms and directing crossover events into more diverged regions. In this review, we demonstrate how interhomolog polymorphism may affect crossover chromosomal distribution and, as a consequence, plant genomes evolution. It is especially important for self-fertilizing plants which naturally exhibit high level of homozygosity. If recombination were to occur only in homozygous regions, no new genotypes would be created in subsequent generations, slowing down the evolution of the organisms.

Dual Role of the Histone Variant H2A.Z in Transcriptional Regulation of Stress-Response Genes.

The influence of the histone variant H2A.Z on transcription remains a long-standing conundrum. Here, by analyzing the actin-related protein6 mutant, which is impaired in H2A.Z deposition, and by H2A.Z profiling in stress conditions, we investigated the impact of this histone variant on gene expression in Arabidopsis thaliana We demonstrate that the arp6 mutant exhibits anomalies in response to osmotic stress. Indeed, stress-responsive genes are overrepresented among those hyperactive in arp6. In wild-type plants, these genes exhibit high levels of H2A.Z in the gene body. Furthermore, we observed that in drought-responsive genes, levels of H2A.Z in the gene body correlate with transcript levels. H2A.Z occupancy, but not distribution, changes in parallel with transcriptional changes. In particular, we observed H2A.Z loss upon transcriptional activation and H2A.Z gain upon repression. These data suggest that H2A.Z has a repressive role in transcription and counteracts unwanted expression in noninductive conditions. However, reduced activity of some genes in arp6 is associated with distinct behavior of H2A.Z at their +1 nucleosome, which exemplifies the requirement of this histone for transcription. Our data support a model where H2A.Z in gene bodies has a strong repressive effect on transcription, whereas in +1 nucleosomes, it is important for maintaining the activity of some genes.

The Assessment of the Combined Treatment of 5-ALA Mediated Photodynamic Therapy and Thalidomide on 4T1 Breast Carcinoma and 2H11 Endothelial Cell Line.

Photodynamic therapy (PDT) is a low-invasive method of treatment of various diseases, mainly neoplastic conditions. PDT has been experimentally combined with multiple treatment methods. In this study, we tested a combination of 5-aminolevulinic acid (5-ALA) mediated PDT with thalidomide (TMD), which is a drug presently used in the treatment of plasma cell myeloma. TMD and PDT share similar modes of action in neoplastic conditions. Using 4T1 murine breast carcinoma and 2H11 murine endothelial cells lines as an experimental tumor model, we tested 5-ALA-PDT and TMD combination in terms of cytotoxicity, apoptosis, Vascular Endothelial Growth Factor (VEGF) expression, and, in 2H11 cells, migration capabilities by wound healing assay. We have found an enhancement of cytotoxicity in 4T1 cells, whereas, in normal 2H11 cells, this effect was not statistically significant. The addition of TMD decreased the production of VEGF after PDT in 2H11 cell line. Our results reveal enhanced effectiveness of 5-ALA-PDT with TMD treatment compared to 5-ALA-PDT or TMD treatment alone. The addition of TMD may be a promising proceeding of the anti-tumor effect of PDT by decreasing the VEGF concentration in the culture medium. Further studies, including testing on different cell lines, are needed to confirm this assumption.

Recombination Rate Heterogeneity within Arabidopsis Disease Resistance Genes.

Meiotic crossover frequency varies extensively along chromosomes and is typically concentrated in hotspots. As recombination increases genetic diversity, hotspots are predicted to occur at immunity genes, where variation may be beneficial. A major component of plant immunity is recognition of pathogen Avirulence (Avr) effectors by resistance (R) genes that encode NBS-LRR domain proteins. Therefore, we sought to test whether NBS-LRR genes would overlap with meiotic crossover hotspots using experimental genetics in Arabidopsis thaliana. NBS-LRR genes tend to physically cluster in plant genomes; for example, in Arabidopsis most are located in large clusters on the south arms of chromosomes 1 and 5. We experimentally mapped 1,439 crossovers within these clusters and observed NBS-LRR gene associated hotspots, which were also detected as historical hotspots via analysis of linkage disequilibrium. However, we also observed NBS-LRR gene coldspots, which in some cases correlate with structural heterozygosity. To study recombination at the fine-scale we used high-throughput sequencing to analyze ~1,000 crossovers within the RESISTANCE TO ALBUGO CANDIDA1 (RAC1) R gene hotspot. This revealed elevated intragenic crossovers, overlapping nucleosome-occupied exons that encode the TIR, NBS and LRR domains. The highest RAC1 recombination frequency was promoter-proximal and overlapped CTT-repeat DNA sequence motifs, which have previously been associated with plant crossover hotspots. Additionally, we show a significant influence of natural genetic variation on NBS-LRR cluster recombination rates, using crosses between Arabidopsis ecotypes. In conclusion, we show that a subset of NBS-LRR genes are strong hotspots, whereas others are coldspots. This reveals a complex recombination landscape in Arabidopsis NBS-LRR genes, which we propose results from varying coevolutionary pressures exerted by host-pathogen relationships, and is influenced by structural heterozygosity.

Photodynamic enhancement of the activity of antibiotics used in urinary tract infections.

Photodynamic therapy (PDT) has been proven to kill different microbial cells. However, to our knowledge, none of the available reports describes the modulatory effect of this therapy on the antibacterial activity of antibiotics against Escherichia coli rods being the main causative agent of urinary tract infections (UTIs). Therefore, the aim of our study was to verify if the PDT can enhance the antibacterial activity of antibiotics recommended in the treatment of UTIs. An attempt to determine the optimal conditions of PDT to enhance the bactericidal activity of ciprofloxacin, amikacin, and colistin has been made. In order to find the optimal antimicrobial conditions, the efficacy of four protocols associated with the use of different energy doses (70 and 120 J/cm2) and chlorin e6 (Ce6) concentrations (50 and 100 µg/mL) has been verified. The antibacterial effect of combined PDT and antibiotics was assessed by the time-kill assay. The best results were achieved for Ce6 at a concentration of 100 µg/mL and the energy dose 120 J/cm2 for bacterial suspensions treated with ciprofloxacin. Taken together, our results showed that PDT using Ce6 improves the antibacterial activity of antibiotics effectively inhibiting bacterial growth and being promising in the elimination of bacterial UTIs in humans.

Breast cancer risk in premalignant lesions: osteopontin splice variants indicate prognosis.

BACKGROUND: Premalignant breast lesions pose variable risks for transformation, raising the question who should receive treatment to counteract the potential progression to breast cancer. Because the secreted metastasis mediator Osteopontin (OPN) is a marker for breast cancer aggressiveness, its presence in these lesions may reflect progression risk. METHODS: By immunohistochemistry, we analyse the association of Osteopontin variant expression in healthy breasts, hyperplasias, papillomas, and carcinomas in situ from 434 women to assess a) staining for OPN exon 4 (present in OPN-a and OPN-b) or OPN-c in low-risk to high-risk lesions b) correlations between staining and progression (DCIS with invasion, invasive cancer) or survival. RESULTS: The markers correlate with risk, and they are prognostic for ensuing invasive disease and survival. About 10% of OPN-c pathology score 0-1 (intensity), vs. 40% of score 3 experience cancer over 5 years. More than 90% of women, who progress, had pathology scores of 2-3 for OPN-c intensity at the time of initial diagnosis. When combining OPN-c and OPN exon 4 staining, all of the low intensity patients are alive after 5 years, whereas women in the high category have a close to 30% chance to die within 5 years. Of patients who succumb, close to 80% had a high combined score at the time of initial diagnosis. CONCLUSION: The combined information of OPN splice variant immunohistochemistry can provide a foundation for very reliable prognostication and has the potential to aid decision making in the treatment of early breast lesions.

Physiological Hypoxia (Physioxia) Impairs the Early Adhesion of Single Lymphoma Cell to Marrow Stromal Cell and Extracellular Matrix. Optical Tweezers Study.

Adhesion is critical for the maintenance of cellular structures as well as intercellular communication, and its dysfunction occurs prevalently during cancer progression. Recently, a growing number of studies indicated the ability of oxygen to regulate adhesion molecules expression, however, the influence of physiological hypoxia (physioxia) on cell adhesion remains elusive. Thus, here we aimed: (i) to develop an optical tweezers based assay to precisely evaluate single diffuse large B-cell lymphoma (DLBCL) cell adhesion to neighbor cells (mesenchymal stromal cells) and extracellular matrix (Matrigel) under normoxia and physioxia; and, (ii) to explore the role of integrins in adhesion of single lymphoma cell. We identified the pronouncedly reduced adhesive properties of lymphoma cell lines and primary lymphocytes B under physioxia to both stromal cells and Matrigel. Corresponding effects were shown in bulk adhesion assays. Then we emphasized that impaired ß1, ß2 integrins, and cadherin-2 expression, studied by confocal microscopy, account for reduction in lymphocyte adhesion in physioxia. Additionally, the blockade studies conducted with anti-integrin antibodies have revealed the critical role of integrins in lymphoma adhesion. To summarize, the presented approach allows for precise confirmation of the changes in single cell adhesion properties provoked by physiological hypoxia. Thus, our findings reveal an unprecedented role of using physiologically relevant oxygen conditioning and single cell adhesion approaches when investigating tumor adhesion in vitro.

Protective effects of levamisole, acetylsalicylic acid, and α-tocopherol against dioxin toxicity measured as the expression of AhR and COX-2 in a chicken embryo model.

Polychlorinated dibenzo-p-dioxins and dibenzofurans (dioxins) are classed as persistent organic pollutants and have adverse effects on multiple functions within the body. Dioxins are known carcinogens, immunotoxins, and teratogens. Dioxins are transformed in vivo, and interactions between the products and the aryl hydrocarbon receptor (AhR) lead to the formation of proinflammatory and toxic metabolites. The aim of this study was to determine whether α-tocopherol (vitamin E), acetylsalicylic acid (ASA), and levamisole can decrease the amount of damage caused by dioxins. Fertile Hubbard Flex commercial line chicken eggs were injected with solutions containing 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or containing TCDD and the test compounds. The chicken embryos and organs were analyzed after 7 and 13 days. The levels at which AhR and cyclooxygenase-2 (COX-2) proteins (which are induced during inflammation) were expressed were evaluated by performing immunohistochemical analyses on embryos treated with TCDD alone or with TCDD and the test compounds. TCDD caused developmental disorders and increased AhR and COX-2 expression in the chicken embryo tissues. Vitamin E, levamisole, ASA, and ASA plus vitamin E inhibited AhR and COX-2 expression in embryos after 7 days and decreased AhR and COX-2 expression in embryos after 13 days. ASA, levamisole, and ASA plus vitamin E weakened the immune response and prevented multiple organ changes. Vitamin E was not fully protective against developmental changes in the embryos.

Interconnections between meiotic recombination and sequence polymorphism in plant genomes.

1022 I. 1022 II. 1023 III. 1023 IV. 1025 V. 1026 1027 References 1027 SUMMARY: Meiosis is fundamental to sexual reproduction and creates genetic variation in progeny. During meiosis paired homologous chromosomes undergo recombination, which can result in reciprocal crossovers. This process can recombine independently arising mutations onto the same chromosome. Recombination locations are highly variable between meioses, although total crossover numbers are tightly regulated. In addition to the effect of meiosis on genetic variation, sequence polymorphisms between homologous chromosomes can feedback onto the recombination pathways. Here we review the major crossover pathways in plants and some of the known homeostatic mechanisms that act during meiotic recombination. We then examine how sequence polymorphisms between homologous chromosomes, that is, heterozygosity, can influence meiotic recombination pathways in cis and trans. Finally, we provide a brief perspective on the relevance of these interconnections for natural selection and adaptation in plants.