Anaphase Stages Research Articles

Cytogenetic monitoring of spontaneous mutagenesis

Due to the challenging environmental situation in Ukraine, there is a need for cytogenetic monitoring, establishing cause-and-effect relationships, and assessing the toxic-mutagenic activity of environmental components. The results of such monitoring can serve as a basis for developing rehabilitation measures aimed at improving the environmental condition. Cytogenetic bioassay methods allow the evaluation of ecological and genetic risks to biota, considering the overall impact of pollutants, predicting changes in ecosystems, and making timely management decisions to improve environmental quality and preserve the nation’s gene pool. The article provides cytogenetic monitoring of apical meristems of the roots of Raphanus sativus subsp. radicula (Pers.) DC. and Allium cepa L. seedlings., grown on soils of residential areas, and the effect of ions of some elements on the cytological parameters of Pisum sativum L. was studied. It was noted that the spectrum of mitosis abnormalities and chromosome aberrations was expanded due to lagging chromosomes and micronuclei. Residential areas with a consistently high level of spontaneous cytogenetic disorders require the development of a local monitoring system to identify genetic hazards. The research on the proliferative activity of apical meristem cells confirms the hypothesis of aluminum toxicity to plants. Cytotoxic effects are assessed at the micro- and macroscopic levels. Macroscopically, reduced root growth of bioindicator plants was observed, which may result from several possible mechanisms: cell death, inhibition of division, cell elongation, or nutrient absorption. It was found that the duration of the prophase is directly influenced by the mobile forms of Zn and Pb, while Cu has a reverse effect. According to the results of multiple regression analysis, the most significant influence on these processes is exerted by the mobile forms of Zn, Cu, and Pb in the surface layers of the soils of the studied residential areas. Under the influence of AlCl3, the proportion of cells in the anaphase stage increases; CdCl2 affects the prophase stage; Na2SeO3 affects the meta- and anaphase stages; X-ray irradiation affects the telophase stage. Regarding the ability to induce the frequency of aberrant anaphases, a ranking can be constructed: Na2SeO3 (3.75·10–6 M) > AlCl3 (3.86·10–5 M) > CdCl2 (8.44·10–5 M). A radiation dose of 9.03·10–3 C/kg leads to the frequency of chromosomal aberrations, similar to the effects of AlCl3 (3.86·10–4 M) and Na2SeO3 (8.34·10–6 M). High concentrations of aluminum are associated with an increase in anaphases with fragments and two to three bridges.

Genotoxicity of Gamma Radiation Against Lymphocytes of Radiation Workers: The Cytokinesis-Block Micronucleus Assay.

<b>Background and Objective:</b> Gamma irradiation induces genotoxicity, characterized by the formation of extra-nuclear bodies and left behind during the anaphase stage of cell division, often referred to as a micronucleus (MN). The present work aims to monitor exposure to ionizing radiation as a genotoxic agent in the lymphocytes of workers at radiation energy centers. <b>Materials and Methods:</b> The lymphocyte cytokinesis block micronucleus assay used and analyzed the correlation between the Nuclear Division Index (NDI), age, blood type and the number of micronuclei (MN). Blood samples were collected from 20 volunteers in heparin tubes, exposed to 2 Gy gamma rays and cultured <i>in vitro</i>. <b>Results:</b> A significant difference in the number of micronuclei between blood group A and blood groups A, B and AB. The Nuclear Division Index (NDI) value for lymphocytes of radiation energy center workers after gamma radiation was significant (1.74±0.1) but still within the normal range. Neither MN frequency nor NDI values correlated with age, but MN frequency showed a correlation with blood type. <b>Conclusion:</b> The gamma irradiation did not induce a cytostatic effect but proved genotoxic to the lymphocytes of radiation energy center workers. Notably, blood type A demonstrated higher sensitivity to gamma radiation.

Microtubule length correlates with spindle length in C. elegans meiosis.

The accurate segregation of chromosomes during female meiosis relies on the precise assembly and function of the meiotic spindle, a dynamic structure primarily composed of microtubules. Despite the crucial role of microtubule dynamics in this process, the relationship between microtubule length and spindle size remains elusive. Leveraging Caenorhabditis elegans as a model system, we combined electron tomography and live imaging to investigate this correlation. Our analysis revealed significant changes in spindle length throughout meiosis, coupled with alterations in microtubule length. Surprisingly, while spindle size decreases during the initial stages of anaphase, the size of antiparallel microtubule overlap decreased as well. Detailed electron tomography shows a positive correlation between microtubule length and spindle size, indicating a role of microtubule length in determining spindle dimensions. Notably, microtubule numbers displayed no significant association with spindle length, highlighting the dominance of microtubule length regulation in spindle size determination. Depletion of the microtubule depolymerase KLP-7 led to elongated metaphase spindles with increased microtubule length, supporting the link between microtubule length and spindle size. These findings underscore the pivotal role of regulating microtubule dynamics, and thus microtubule length, in governing spindle rearrangements during meiotic division, shedding light on fundamental mechanisms dictating spindle architecture.

Meiotic analysis of induced translocation heterozygotes in Lepidium sativum Linn.

Aim: To assess the cytological effects of Gamma rays on the pollen mother cells and post meiotic products of Lepidium sativum Linn. which resulted in isolation of translocation heterozygote and aneuploid gametes. Methodology: During the experiment, parameters such as Meiotic stages, chromosomal structure, and pollen fertility were studied. Fresh seeds of Garden cress were orderly arranged in plastic and divided into four groups. The fresh seeds of each group were individually irradiated with 60Gy, 150Gy, 300Gy, 450Gy and 600Gy @ 7.247KGyh-1 in the Floriculture Laboratory of National Botanical Research Institute (NBRI), Lucknow (India). The source for gamma ray irradiation was Cobalt-60. The irradiated seeds were sown in triplicates along with their respective controls. Results: Meiotic analysis of pollen mother cells (PMCs) at 300Gy showed translocation heterozygotes, however, in the control sets, the rate was negligible and phenotypically the plants were weak and short heighted. The cytological illustration of chromosomal configuration at diakinesis and metaphase I exhibited the superiority of tetravalents, bivalent and other forms of chromosomal associations such as multivalents. The induced translocation heterozygotes resulted in stickiness at metaphase and anaphase states along with the formation of bridges at anaphase stage. Due to chromosomal anomalies, the pollen fertility was reduced to 37.54±0.25% in contrast to control plants (98.20±0.16%). Interpretation: The current research work would be of paramount interest as translocation heterozygote serves as a source for raising aneuploid offspring having novel genetic combinations. Key words: Chromosomal anomalies, Heterozygotes, Lepidium sativum Linn, Meiosis, Pollen fertility

Assessment of Genotoxicity of Zinc Oxide Nanoparticles Using Mosquito as Test Model.

The widespread applications of ZnO NPs in the different areas of science, technology, medicine, agriculture, and commercial products have led to increased chances of their release into the environment. This created a growing public concern about the toxicological and environmental effects of the nanoparticles. The impact of these NPs on the genetic materials of living organisms is documented in some cultured cells and plants, but there are only a few studies regarding this aspect in animals. In view of this, the present work regarding the assessment of the genotoxicity of zinc oxide nanoparticles using the mosquito Culex quinquefaciatus has been taken up. Statistically significant chromosomal aberrations over the control are recorded after the exposure of the fourth instar larvae to a dose of less than LD20 for 24 h. In order to select this dose, LD20 of ZnO NPs for the mosquito is determined by Probit analysis. Lacto-aceto-orcein stained chromosomal preparations are made from gonads of adult treated and control mosquitoes. Both structural aberrations, such as chromosomal breaks, fragments, translocations, and terminal fusions, resulting in the formation of rings and clumped chromosomes, and numerical ones, including hypo- and hyper-aneuploidy at metaphases, bridges, and laggards at the anaphase stage are observed. The percentage frequency of abnormalities in the shape of sperm heads is also found to be statistically significant over the controls. Besides this, zinc oxide nanoparticles are also found to affect the reproductive potential and embryo development as egg rafts obtained from the genetic crosses of ZnO nanoparticle-treated virgin females and normal males are small in size with a far smaller number of eggs per raft. The percentage frequencies of dominant lethal mutations indicated by the frequency of unhatched eggs are also statistically significant (p < 0.05) over the control. The induction of abnormalities in all of the three short-term assays studied during the present piece of work indicates the genotoxic potential of ZnO NPs, which cannot be labeled absolutely safe, and this study pinpoints the need to develop strategies for the protection of the environment and living organisms thriving in it.

Structural evidence for elastic tethers connecting separating chromosomes in crane-fly spermatocytes.

Different types of anaphase bridges are reported to form between segregating chromosomes during cell division. Previous studies using laser microsurgery suggested that elastic tethers connect the telomeres of separating anaphase chromosomes in many animal meiotic and mitotic cells. However, structural evidence is lacking for their existence. In this study, by correlating live imaging with electron tomography, we examined whether visible structures connect separating telomeres in meiosis I of crane-fly primary spermatocytes. We found structures extending between separating telomeres in all stages of anaphase. The structures consist of two components: one is darkly stained, looking somewhat like chromatin, whereas the other is more lightly stained, appearing filamentous. Although in early anaphase both structures extend between telomeres, in later anaphase, the darker structure extends shorter distances from the telomeres but the lighter structure still extends between the separating telomeres. From these observations, we deduced that these structures represent the "tethers" inferred from the laser-cutting experiments. Because elastic tethers have been detected in a variety of animal cells, they probably are present during anaphase in all animal cells.

Evaluation &amp; comparison of micronuclei in smokers with &amp; without diabetes

Background: Micronuclei are chromatin masses that arise from chromosomal fragments or whole chromosome that lack behind at the anaphase stage of cell division. Their presence in cells means the number of chromosomal aberrations arising during mitosis. Cigarette smoke contains over 4000 chemical carcinogens, with 200 known carcinogens that show significant genotoxic effects in human cells. Chronic high levels of glucose during Diabetes Mellitus are thought to increase oxidative stress and the formation of free radicals that in turn damage cells. Reactive oxygen species chemically attack cellular components altering metabolism, inflammatory mediators, and antioxidant defense mechanisms, overall favoring the pathogenesis of the disease and the persistence of genetic damage. Scoring of micronuclei is considered a DNA damage biomarker for chromosomal damage and instability. Aim: Considering this, we decided to evaluate & compare the frequency of micronuclei in oral epithelial cells in smokers & in diabetics. Materials & Methods: A total number of eligible 150 individuals were included in the study; 50 smokers without diabetes, 50 smokers with diabetes & 50 age and sex matched non smoker healthy individuals group as controls. Oral epithelial cells were taken from buccal smears and subjected to PAP stain. Mean micronuclei were taken from all the subjects. Results: Least number of micronuclei was found in non smoker, non diabetic group & highest numbers were found in smoker, Diabetic group. Conclusion: Micronuclei assay is non-invasive technique that offers a very simple method for obtaining information on status of the epithelial cells, particularly DNA damage, proliferative potential of basal cells and cell death.

Protective effect of zinc complex with hypoxanthine-9-riboside on wheat seedlings grown from gamma-irradiated seeds

Aim. The aim of the research was to obtain the zinc complex hypoxanthine-9-riboside and to study its effect during γ-irradiation on the biosynthesis of chlorophylls, carotenoids and on the release of chromosome aberrations in anaphase root hair cells in wheat seedlings. Methods. The zinc complex was obtained by direct interaction of zinc chloride – ZnCl2 with hypoxanthine-9-riboside. X-ray phase analysis and thermogravimetric measurements of the obtained complex were carried out. Before irradiation, seeds of durum wheat Triticum durum L. from a 60Co source were treated with a zinc complex with hypoxanthine-9-riboside at concentrations of 0.1; 0.01; 0.001%. Structural changes in chromosomes were determined in the initial and final stages of anaphase. Determination of chlorophylls and carotenoids was carried out according to Shlyk. Results. g-irradiation at doses of 50, 100 and 200 Gy has a significant effect on the content of green pigments and carotenoids in wheat seedlings. Under the action of g-irradiation, the content of chlorophyll decreases more than carotenoids. With an increase in the dose of radiation, a slight increase in the content of carotenoids is noted. In all variants, chromosomal abnormalities were found: the formation of fragments in metaphase and anaphase, bridges in anaphase, chromosome delays, uneven division of chromosomes. Conclusions. For the first time, it was found that the Zn (II) complex of hypoxanthine-9-riboside at the indicated concentrations significantly reduces the damaging effect of γ-irradiation, helps to eliminate abnormalities in mitotic division in wheat root hair cells.

Dynamics and Equilibration Mechanisms in Block Copolymer Particles.

Self-assembly of block copolymers into interesting and useful nanostructures, in both solution and bulk, is a vibrant research arena. While much attention has been paid to characterization and prediction of equilibrium phases, the associated dynamic processes are far from fully understood. Here, we explore what is known and not known about the equilibration of particle phases in the bulk, and spherical micelles in solution. The presumed primary equilibration mechanisms are chain exchange, fusion, and fragmentation. These processes have been extensively studied in surfactants and lipids, where they occur on subsecond time scales. In contrast, increased chain lengths in block copolymers create much larger barriers, and time scales can become prohibitively slow. In practice, equilibration of block copolymers is achievable only in proximity to the critical micelle temperature (in solution) or the order-disorder transition (in the bulk). Detailed theories for these processes in block copolymers are few. In the bulk, the rate of chain exchange can be quantified by tracer diffusion measurements. Often the rate of equilibration, in terms of number density and aggregation number of particles, is much slower than chain exchange, and consequently observed particle phases are often metastable. This is particularly true in regions of the phase diagram where Frank-Kasper phases occur. Chain exchange in solution has been explored quantitatively by time-resolved SANS, but the results are not well captured by theory. Computer simulations, particularly via dissipative particle dynamics, are beginning to shed light on the chain escape mechanism at the molecular level. The rate of fragmentation has been quantified in a few experimental systems, and TEM images support a mechanism akin to the anaphase stage of mitosis in cells, via a thin neck that pinches off to produce two smaller micelles. Direct measurements of micelle fusion are quite rare. Suggestions for future theoretical, computational, and experimental efforts are offered.

S. cerevisiae Cells Can Grow without the Pds5 Cohesin Subunit.

ABSTRACTDuring DNA replication, the newly created sister chromatids are held together until their separation at anaphase. The cohesin complex is in charge of creating and maintaining sister chromatid cohesion (SCC) in all eukaryotes. In Saccharomyces cerevisiae cells, cohesin is composed of two elongated proteins, Smc1 and Smc3, bridged by the kleisin Mcd1/Scc1. The latter also acts as a scaffold for three additional proteins, Scc3/Irr1, Wpl1/Rad61, and Pds5. Although the HEAT-repeat protein Pds5 is essential for cohesion, its precise function is still debated. Deletion of the ELG1 gene, encoding a PCNA unloader, can partially suppress the temperature-sensitive pds5-1 allele, but not a complete deletion of PDS5. We carried out a genetic screen for high-copy-number suppressors and another for spontaneously arising mutants, allowing the survival of a pds5Δ elg1Δ strain. Our results show that cells remain viable in the absence of Pds5 provided that there is both an elevation in the level of Mcd1 (which can be due to mutations in the CLN2 gene, encoding a G1 cyclin), and an increase in the level of SUMO-modified PCNA on chromatin (caused by lack of PCNA unloading in elg1Δ mutants). The elevated SUMO-PCNA levels increase the recruitment of the Srs2 helicase, which evicts Rad51 molecules from the moving fork, creating single-stranded DNA (ssDNA) regions that serve as sites for increased cohesin loading and SCC establishment. Thus, our results delineate a double role for Pds5 in protecting the cohesin ring and interacting with the DNA replication machinery.

Plant growth regulatory activity in the phytopathogenic fungus Plectosphaerella melonis strain 502

Aim. To investigate the ability of our phytopathogenic fungal strain 502, earlier preliminarily identified as the phytopathogen Plectosphaerella melonis (syn. Acremonium cucurbitacearum), to have phytotoxic and/or plant growth regulatory activity. Methods. The phytotoxicity of strain 502, was studied by bioassays using the test cultures of corn (Zea mays L.), garden cress (Lepidium sativum L.), cucumber (Cucumis sativus L.), and onion (Allium cepa L.). The cytotoxicity and genotoxicity of the fungus were estimated using the Allium cepa-test. The mitotic index of the, the duration of mitosis phases, and the frequency of aberrant ana-telophases of Allium cepa L. roots meristem was also investigated. For this purpose, strain 502, was grown in the following culture media: synthetic Raulin-Thom medium for 10 days at 26 ± 2 °С. Cell-free filtrate (culture fluid) was used for the study. Ethylene production was quantified in culture filtrate using gas-chromatography meth- od. Ethylene measurement was performed every 7 days during 8 weeks. The determination was carried out using a gas chromatograph «Agilent Technologies 6850» (USA) fitted with a flame ionization detector, using commercial ethylene as a standard for identification and quantification Every experiment had three repeats. The reliability of experimental data was assessed by statistical methods using Statistica 12 (Stat-Soft Inc., USA). Results. Undiluted culture fluid (obtained by growing the fungus on liquid wort) of our strain 502 inhibited the growth of Z. mays seedlings by 14 %, L. sativum seedlings by 18 % (1 : 100 dilution) and stimulated the growth of L. sativum roots by 54 and 41 % (1 : 10 and 1 : 100 dilutions, respectively). The culture fluid, obtained by growing the fungus on Raulin-Thom’s synthetic agar, demonstrated a slight inhibitory effect on the seedlings and roots of L. sativum, and at the dilution of 1 : 1000 stimulated growth by 30 %. Insignificant changes in the mitotic index of the meristem of A. cepa roots were revealed at the effect of the culture fluid of P. melonis, strain 502, diluted at the ratio of 1 : 100 and 1 : 1000. At the same time, the number of cells at the prophase stage decreased 1.7 times (1 : 100 dilution). There is a significant increase in the number of cells at the metaphase stage – 1.3 and 1.4 times (dilution 1 : 100 and 1 : 1000, respectively), the anaphase stage – 2.1 and 1.8 times (dilution 1 : 100 and 1 : 1000, respectively) and the telophase stage – 1.8 times (1 : 100 dilution), as compared with the positive control (culture medium). The frequencies of aberrant ana-telophases in the apical meristems of the initial roots were 5.0 and 2.2 % (at the culture fluid dilution of 1 : 100 and 1 : 1000, respectively). We researched the abil- ity of P. melonis 502 to synthesize ethylene and the highest level of it was registered after 5 weeks of cultivation (111.78 nmol/h g). Conclusions: It was demonstrated by us that the culture fluid of strain 502 showed no phytotoxic effect on roots and seedlings of the investigated cultures, demonstrating the exclusion of phytotoxins from the possible range of effectors. No cytotoxic or genotoxic activity of the culture fluid was observed either. However, the culture fluid altered the dynamics of the cell cycle, in particular, shortened the prophase and stimulated the metaphase, anaphase, and telophase. The culture fluid of the fungus stimulated the growth of L. sativum roots depending on the nutrient medium, where the fungus was grown and cultivated. In particular, when growing the fungus on the liquid wort, the growth was higher by 54 and 41 % (dilution 1 : 10 and 1 : 100, respectively), when growing on synthetic Raulin-Thom’s medium – by 30 %. This demonstrates the ability of strain 502 to possibly synthesize growth promoting substances. Also, we have shown the ability of this strain to synthetize ethylene in vitro (111.78 ± 13.27 nmol/h per g), which can act as virulence factor. We consider the obtained results to be the first stage of the study on the mechanism of the interaction between pathogenic strain 502 and plants.

Producing magnetite concentrate via self-magnetization roasting in N2 atmosphere: Phase and structure transformation, and extraction kinetics

In this work, a green self-magnetization roasting technology for producing magnetite was proposed without adding additional. The regulatory mechanisms of the main factors (siderite dosage, roasting temperature, and roasting time) on the self-magnetization roasting process were investigated. In-situ kinetic of the self-magnetization roasting process was analyzed by the infrared gas analyzer, and the phase transformation was investigated by in-situ X-ray diffraction and Mössbauer. Under the optimal roasting conditions of 30% siderite dosage, 730 °C, and 7.5 min, the iron concentrate with Fe grade 68.82% and Fe recovery 99.48% was obtained. The kinetic and phase transformation results indicated that the self-magnetization roasting process was divided into two stages: siderite pyrolysis in the prophase stage, and hematite reduced to magnetite by reductant (FeO and CO) from siderite pyrolysis in the anaphase stage. The SEM analyses showed that the newborn magnetite crystals were mainly coarse-grained and needles, which fitted the kinetics characteristics for the Nucleation model. Using self-magnetization roasting technology, siderite and hematite would promote mutual reduction to improve product magnetism and roasting efficiency without adding reductant. Also, self-magnetization roasting will enhance the utilization rate of siderite, and it contributes to energy conservation and CO2 emission reduction.

Chlorogenic acid and caffeine combination attenuates adipogenesis by regulating fat metabolism and inhibiting adipocyte differentiation in 3T3-L1 cells.

Obesity is a complex disease spreading in the world. In our previous studies, chlorogenic acid (CGA) and caffeine had ever been reported to reduce the body weight gain and fat accumulation in mice. This study investigated the anti-obesity effect of CGA and caffeine on 3T3-L1 cells. According to triglyceride (TG) assay and Oil-Red O staining, 40μg/ml CGA and 160μg/ml caffeine reduced TG content. Moreover, CGA+caffeine inhibited the mRNA expression of major adipogenic markers, PPAR-γ2, and C/EBPα in the metaphase and anaphase stages of differentiation induction (Day 2 and 4). CGA+caffeine improved P-AMPK/AMPK accompanied by decreasing the expression of GPDH and FAS to depress the lipid synthesis, increasing the mRNA expression of ACO and CAT to promote fatty acid oxidation and up-regulated the expression of hydrolysis-related enzyme adipose TG lipase (ATGL) and P-HSL/HSL. Furthermore, CGA+caffeine improved the expression of Glut4 which promoted the glucose transport. Taken together, these data demonstrated CGA+caffeine inhibited 3T3-L1 cells differentiation in the middle and late stages and reduced the fat accumulation through AMPK pathway by regulating the fat metabolism-related enzyme in 3T3-L1 cells to attenuates adipogenesis. PRACTICAL APPLICATIONS: The aim of this study was to elucidate the potential role of chlorogenic acid and caffeine in the treatment of obesity.

The assessment of the environmental hazard of isomers of 1,2,4-triazole phenolic derivatives for natural ecosystems

Its necessary to synthesize homologues of compounds frequently used in practice and to analyze their biological activity in laboratory experiments using screening tests that provide an integral assessment of biological responses to assess the effect of anthropogenic xenobiotics with different structures on ecosystems adjacent to agricultural complexes. We analyzed alcohol solutions of 2-(1H-1,2,4-triazolyl-methyl)phenol (ortho-isomer) and 4-(1H-1,2,4-triazolyl-methyl)phenol (para-isomer) in three concentrations: 0,0001; 0,001; 0.01 mg/ml using the Allium-test. The solvent was 0,1% isopropyl alcohol; the test object was Allium fistulosum L. The duration of the experiment was 5 days. Triazolide solutions significantly inhibited seed germination at all investigated concentrations. However, no significant differences were found between the isomers and the studied concentrations. Both isomers inhibited root growth at all concentrations tested. The toxicity of a triazolide containing an OH group in the para-position didnt change over the selected concentration range. For its ortho-isomer, toxicity increased with increasing concentration, reaching the toxicity of its homologue at a dose of 0,01 mg/ml. Both tested compounds significantly inhibited the proliferation of meristem cells as compared to the control. At the same time, no differences were observed in the effect of homologues with the OH-group in the para- and ortho-position on the value of the mitotic index. However, we found a paradoxical reaction: both homologues showed maximum cytotoxicity at a minimum concentration of 0,0001 mg/ml, and cytotoxicity decreased with increasing concentration compared to control. A triazolid containing an OH group in the para-position caused a block at the metaphase and anaphase stages at the lowest concentration. The specificity of its action disappeared with an increase in concentration, which was expressed in a general prophase and metaphase block. Its ortho-isomer inhibited cell division at all concentrations at the prophase stage. Both compounds are mutagenic. The number of chromosomal aberrations depended on both the structure of the compounds and their concentration. The para-homologue is less mutagenic than ortho. In the ortho-homologue, mutagenicity decreased slightly with increasing concentration. The highest mutagenicity was found for the ortho-homologue at its lowest concentration. The paper discusses possible mechanisms of action of isomers and their negative impact on plant organisms in ecosystems.

Chromosome segregation during female meiosis in C. elegans: A tale of pushing and pulling.

The role of the kinetochore during meiotic chromosome segregation in C. elegans oocytes has been a matter of controversy. Danlasky et al. (2020. J. Cell. Biol.https://doi.org/10.1083/jcb.202005179) show that kinetochore proteins KNL-1 and KNL-3 are required for early stages of anaphase during female meiosis, suggesting a new kinetochore-based model of chromosome segregation.

Giant multinucleated plasma cells in relapsed plasma cell myeloma.

A 47-year-old woman was diagnosed with plasma cell myeloma in 2018, received first-line induction chemotherapy, and made a partial response. She then received two cycles of DT-PACE chemotherapy. Her paraprotein levels remained static and a repeat bone marrow test in February 2019 revealed persistent bone marrow involvement by plasma cell myeloma showing usual (mononuclear) morphology with no multinucleated giant cells. She was treated with daratumumab as a bridge to an autologous stem cell transplant in June 2019. Her day 100 post autograft bone marrow trephine biopsy contained a plasma cell population making up 10% of all nucleated cells. More than 95% of the atypical plasma cells showed multinucleated giant cell morphology containing up to 40 nuclei. On immunohistochemistry, these multinucleated giant cells showed positive staining for CD138, CD38, and CD56 and were lambda restricted. CD45 was negative. Bone marrow trephine sections stained (clockwise from top left) with H&E, and for CD138, lambda light chains, and CD38. Multinucleated tumor giant cells are thought to form by two mechanisms: by cell-cell fusion via syncytins or as a result of a failure of cytokinesis at the end of the anaphase stage of mitosis. Occasional case reports of giant multinucleated plasma cells have been published since the 1970s. However, the presence of giant plasma cells with more than 10 nuclei is extremely rare. One previous case had also been treated with daratumumab, an IgG1k monoclonal antibody directed against cell surface CD38 (Guijarro F, Rozman M, Matutes E. Multinucleated giant myeloma cells after failure of daratumumab therapy. Br J Haematol 2018;181:432). Plasma cell membrane alterations promoting cell-cell fusion may be a side effect of immunotherapies targeting cell surface molecules. Giant multinucleated plasma cells may be observed more frequently as such immunotherapies become increasingly used.

Chemical characterization in hydraulic fracturing flowback and produced water (HF-FPW) of shale gas in Sichuan of China.

Large amounts of fracturing flowback and wastewater with complex compositions are produced during hydraulic fracturing. Characterization of hydraulic fracturing flowback and produced water (HF-FPW) is an important initial step in efforts to determine a suitable treatment method for this type of wastewater. In the present study, fracturing flowback and produced water samples were obtained from well CN-F and well CN-E in the prophase and anaphase stages of the Changning shale gas mining area. Chemical characterization of inorganic and organic substances was then conducted. Metal contents were determined by inductively coupled plasma optical emission spectroscopy (ICP-OES), and all inorganic anions involved were determined by ion chromatography. The organic pollutant components were analyzed in detail by combining Fourier transform infrared spectrometer (FTIR) and gas chromatography-mass spectrometer (GC-MS). Results showed that samples contained salt (TDS = 30,000-50,000mg/L), metals (e.g., 650 ± 50mg/L calcium), and total organic carbon (TOC = 32-178mg/L). The organic substances detected in all samples could be divided into six categories, alkanes, aromatics, halogenated hydrocarbons, alcohols, esters, and ketones. C6-C21 straight-chain alkanes and C7-C13 naphthenes had the highest amount of organic matter, reaching more than 48%. The organic matter contained fracturing fluid additives, such as surfactants (e.g., ethylene glycol), and nitrotrichloromethane, which is a chlorinated product of some additives. These results provide information on the chemical composition of HF-FPW in Sichuan, China, as well as a basis for subsequent processing.

Are Anaphase Events Really Irreversible? The Endmost Stages of Cell Division and the Paradox of the DNA Double-Strand Break Repair.

It has been recently demonstrated that yeast cells are able to partially regress chromosome segregation in telophase as a response to DNA double-strand breaks (DSBs), likely to find a donor sequence for homology-directed repair (HDR). This regression challenges the traditional concept that establishes anaphase events as irreversible, hence opening a new field of research in cell biology. Here, the nature of this new behavior in yeast is summarized and the underlying mechanisms are speculated about. It is also discussed whether it can be reproduced in other eukaryotes. Overall, this work brings forwards the need of understanding how cells attempt to repair DSBs when transiting the latest stages of mitosis, i.e., anaphase and telophase.

Post‐metaphase correction of aberrant kinetochore‐microtubule attachments in mammalian eggs

The accuracy of the two sequential meiotic divisions in oocytes is essential for creating a haploid gamete with a normal chromosomal content. Here, we have analysed the 3D dynamics of chromosomes during the second meiotic division in live mouse oocytes. We find that chromosomes form stable kinetochore–microtubule attachments at the end of prometaphase II stage that are retained until anaphase II onset. Remarkably, we observe that more than 20% of the kinetochore–microtubule attachments at the metaphase II stage are merotelic or lateral. However, < 1% of all chromosomes at onset of anaphase II are found to lag at the spindle equator and < 10% of the laggards missegregate and give rise to aneuploid gametes. Our results demonstrate that aberrant kinetochore–microtubule attachments are not corrected at the metaphase stage of the second meiotic division. Thus, the accuracy of the chromosome segregation process in mouse oocytes during meiosis II is ensured by an efficient correction process acting at the anaphase stage.

Cytogenetic Abnormalities in Seed Progenies of Pinus Pallasiana D. Don Stands from Technogenic Polluted Lands in the Steppe of Ukraine

Abstract In this study, we compare the pathological mitosis rates, chromosomal abnormalities and nucleolar organizer activity in Pinus pallasiana D. Don seedlings from natural population in the Crimean Mountains and from the urban plantations in the steppe of Ukraine. On the stages of anaphase and telophase of mitosis, such chromosomal abnormalities as bridges were most often found in the seeds of plantations exposed to air pollutants, whereas lead and agglutination of chromosomes were found in seeds from iron ore dump stands. Our studies have shown that P. pallasiana can be used for genotoxic monitoring of technogenic polluted lands.