Ensayo de micronúcleos con bloqueo de la citocinesis como biomarcador de daño genético en poblaciones sobreexpuestas a radiaciones ionizantes / Micronucleus assay as biomarker of DNA damage in population exposed to ionizing radiation

Resumen Introducción: las radiaciones ionizantes (RI) son capaces de perjudicar el ADN; para evaluar este fenómeno es posible utilizar la formación de micronúcleos como biomarcador de efecto temprano del daño radioinducido. El ensayo de micronúcleos con bloqueo de la citocinesis (MNBC) es una técnica citogenética que permite demostrar el impacto de agentes genotóxicos. Propósito: en el presente trabajo se describieron mecanismos moleculares involucrados en la radioinducción de micronúcleos, la técnica del MNBC, los criterios de análisis, sus aplicaciones dentro de la investigación biológica y su extensión a la clínica, con énfasis en su empleo como biomarcador del daño genético en grupos sobreexpuestos a RI. Argumentos para la discusión: el MNBC se considera un método confiable, simple y rápido y existe evidencia de su aplicabilidad para el estudio de los efectos biológicos en casos de riesgo ocupacional y en accidentes radiológicos aislados o a gran escala. Conclusiones: el MNBC es una herramienta valiosa que posibilita estimar las consecuencias por dosis bajas de RI en poblaciones involucradas y, a la vez, orientar la toma de decisiones en cuanto a su prevención o atenuación . De igual forma, puede ser utilizado en análisis del campo de la radiobiología, a fin de detallar las incidencias de las radiaciones ionizantes sobre el ADN.

Abstract Introduction. Ionizing radiation (IR) is capable of causing DNA damage. For the evaluation of this phenomenon it is possible to use chromosomal aberrations as biomarkers. The Cytokinesis-Block Micronucleus assay (CBMN) is a cytogenetic technique that allows to demonstrate the effect of genotoxic agents.Proposition:in the present review, we will describe the molecular mechanisms involved in micronucleus radioinduction, the micronucleus technique and criteria for analysis, its applications within biological research and its extension in clinical research, with emphasis on its application as a biomarker of radioinduced genetic damage. Arguments for discussion: the CBMN is considered a reliable, simple and fast technique and there is evidence of its applicability in the evaluation of biological effects in occupationally exposed personnel and in isolated or large-scale radiological accidents. Conclusions: the CBMN a valuable tool in estimating radiological risk in populations exposed to low doses of IR, allowing to guide decision-making regarding prevention or mitigation of exposure to IR in populations involved. Similarly, the cbmn can be used in research in the field of radiobiology, as a means to describe the effects of ionizing radiation on DNA.

Brazilin downregulates the expression of protein regulator of cytokinesis 1 in bladder cancer T24 cell and BIU87 cell and inhibits the cell proliferation / 肿瘤研究与临床

Objective:To investigate the inhibitory effect of brazilin on bladder cancer cells and its mechanism.Methods:Chemically synthesized brazilin was synthesized by chemical synthesis. Methyl thiazolyl tetrazolium (MTT) method was used to detect the inhibitory effect of synthetic brazilin on bladder cancer cells T24 and BIU87. Proteomic technique was used to detect the effect of brazilin on the level of protein in both cells. Real-time quantitative polymerase chain reaction (qRT-PCR) and Western blot methods were used to verify the effects of brazilin on the expression of protein regulator of cytokinesis 1 (PRC1) of both cells at gene and protein level.Results:MTT method showed that brazilin significantly inhibited the proliferation of bladder cancer cells T24 and BIU87, and its half inhibitory concentration ( IC50) of T24 cell and BIU87 cell was 9.9 μg/ml and 5.1 μg/ml,respectively. Proteomic results showed that brazilin could regulate the protein expression of PRC1 in both cells, which was verified by qRT-PCR and Western blot. Conclusion:Brazilin suppresses bladder cancer cell growth possibly by downregulating PRC1.

Expression and clinical significance of cytokine cyclin 6(CDC6) in pancreatic ductal adenocarcinoma / 国际生物医学工程杂志

Objective:To investigate the expression of cytokine cyclin 6 (CDC6) in pancreatic ductal adenocarcinoma, and its correlation with prognosis.Methods:The expression levels of CDC6 mRNA in pancreatic cancer tissues and normal tissues adjacent to the cancer were analyzed using the gene expression interaction analysis (GEPIA) database, and the correlation between CDC6 and the clinical prognosis of pancreatic cancer was analyzed using Kaplan-Meier. The clinicopathological characteristics of 80 patients with pancreatic ductal adenocarcinoma were retrospectively analyzed. The expression of CDC6 in pancreatic cancer tissues and normal tissues adjacent to the cancer was detected by immunohistochemical staining, and the data were analyzed by Graphpad 8.0 software to explore the clinical significance of high CDC6 protein expression.Results:Immunohistochemical staining results showed that the expression of CDC6 in pancreatic cancer tissues was much higher than that in normal tissues ( P<0.05), and the correlation between CDC6 and age, gender, and tumor grade of pancreatic cancer patients was not statistically significant (all P>0.05), but closely correlated with the size of the tumor ( P<0.05). Conclusions:CDC6 is closely related to the clinical prognosis of pancreatic cancer and is highly expressed in the developmental evolution of pancreatic cancer. Therefore, CDC6 is expected to be a target and potential biomarker for pancreatic cancer therapy.

Levels of the interleukins 17A, 22, and 23 and the S100 protein family in the gingival crevicular fluid of psoriatic patients with or without periodontitis,

Abstract Background: Psoriasis and periodontitis are immunologically mediated chronic inflammatory diseases. Epidemiologic evidence has linked both; however, the change of markers in gingival crevicular fluid has been poorly evaluated. Objective: To evaluate the levels of IL-17A, IL-22, IL-23, S100A7, S100A8, and S100A9 in gingival crevicular fluid of psoriatic and healthy subjects with and without periodontitis and their relations to psoriasis severity. Methods: Cross-sectional study. Sample comprised the following groups: healthy controls without periodontitis or with mild periodontitis (n = 21), healthy controls with moderate or severe periodontitis (n = 18), individuals with psoriasis without or mild periodontitis (n = 11), and individuals with psoriasis and moderate or severe periodontitis (n = 32). Levels of IL-17A, IL-22, IL-23, S100A8, and S100A9 were determined by multiplex assay and S100A7 was measured by ELISA. Results: No inter-group differences in the levels of IL-17A, IL-22, IL-23, and S100A7 were found. S100A8 levels were higher in psoriatic patients than controls (p < 0.05). S100A8 was positively correlated with psoriasis severity in the group with psoriasis (p < 0.05). S100A9 exceeded the detection limits. Study limitations: This pilot study presents a small sample size. Conclusions: The concentrations of S100A8 were highest in psoriatic patients regardless of periodontal health/status. S100A8 was associated with the severity of psoriasis. The concentrations of interleukins and S100A7 were similar in psoriatic patients with or without periodontitis vs. healthy controls.

Expression and clinical significance of PRC1 in soft tissue sarcoma based on data mining and effect of PRC1 on the growth of liposarcoma / 西安交通大学学报(医学版)

Objective: To investigate the expression and clinical significance of protein regulator of cytokinesis 1 (PRC1) in soft tissue sarcoma (STS) and the effects of down-regulating the expression of PRC1 on the proliferation and cell cycle of human liposarcoma cell by data mining. Methods: Oncomine database was used to analyze the expression of PRC1 in STS tissue and normal tissue, which was then verified by TCGA database. The prognosis data downloaded from OncoLnc database were used to analyze the correlation between PRC1 expression and prognosis of STS patients. Meanwhile, to collect PRC1 expression in STS cells, we used publicly available data from the Cancer Cell Line Encyclopedia (CCLE) projects. String database was used to determine the co-expression molecules with PRC1 and map the gene co-expression network. The expressions of PRC1 in liposarcoma cell line SW872 and human subcutaneous preadipocytes (HPA-s) were detected by Western blotting and Real-time PCR. PRC1 was silenced in SW872 cell (SW872-siPRC1) by PRC1 target siRNA with SW872-NC cell as its control. MTT assay was used to detect the proliferation of SW872-siPRC1 and SW872-NC cells; flow cytometry was used to detect the cell cycle. Results: In the Oncomine database, 11 studies involved PRC1 expression in STS tissues and normal tissues. Compared with that of the control, the expression of PRC1 in STS tissues was significantly higher (P<0.05). The results were consistent with those in the TCGA database. The analysis using Oncomine database showed that the high expression level of PRC1 was associated with shorter overall survival (P<0.05). The analysis using CCLE database showed high expression of PRC1 in STS cells (P<0.05). The co-expression network of PRC1 was established by String database, including 11 nodes and 55 connections. PRC1 was over-expressed in liposarcoma cell line SW872. Cell proliferation curve showed that compared with that of SW872-NC cells in the control group, the proliferation of SW872-siPRC1 cells decreased significantly after 48 h and 72 h culture (P<0.05). Compared with SW872-NC cell in the control group, the G1 cell proportion of SW872-siPRC1 cells was (40.27±7.42)%, significantly lower than that of SW872-NC cells (62.01±4.89)%. The G2/M cell proportion of SW872-siPRC1 cells was (25.65±1.54)%, which was significantly higher than that of SW872-NC cells (8.17±0.96)% (both P<0.05). Conclusion: Tumor gene database mining shows that PRC1 is highly expressed in STS tissues and STS cells, which is associated with the patient's prognosis. Silencing PRC1 gene can inhibit the proliferation of liposarcoma SW872 cells and keep the cells staying in G2/M phase. PRC1 plays a role in promoting liposarcoma, which may provide a potential target for the clinical treatment and prognosis of soft tissue sarcoma, especially liposarcoma.

Combined immunodeficiency / 中华实用儿科临床杂志

Combined immunodeficiency (CID) is categorized to the first classification from the international union of immunological societies expert committee for primary immunodeficiency.Severe combined immunodeficiency (SCID) is the most fatal disorder for paediatric clinical operation.Without hematopoietic stem cell transplantation,almost all infants would die before 1 year old,few could survive beyond 2 years old.Hypomorphic mutations in SCID genes can lead to atypical phenotypes.The two special SCID should be focused,Omenn syndrome and graft-versus-host disease,which are caused by expension of autologous and maternal activated and memory T lymphocytes,respectively.Patients with radiosensitive-CID usually present later on life,for whom treatment should be monitored carefully.CID caused by T cells with normal development and inborn error was hotspot research field for example zeta chain-associated protein 70 kDa deficiency.More attention should be paid to CID associated with syndromes for example dedicator of cytokinesis 8 deficiency.Now,the pathogenesis,molecular,clinical,laboratory features and treatment and prognosis are described,in order to support clues for paediatrician's clinical practice.

The application of cytokinesis-block method to analyze cytomics indicators in public health field / 中国医学装备

In recent years, cytokinesis-block method was used to analyze cytomics indicators including micronucleus, nuclear bridge, nuclear bud, nuclear division index, cell apoptosis and cell necrosis. In public health, it has become the common method to explore the impacts of different population structure, environment and occupational exposure for genomic instability, chromosome breakage, chromosome loss and cell proliferation. This article reviews and discusses the application of using cytokinesis block method to analyze cytomics indicators in public health field.

Influences of cytochalasin-B on radiation-induced nucleoplasmic bridges in peripheral blood lymphocytes / 中华放射医学与防护杂志

Objective To explore the influences of the final concentration and adding time of Cytochalasin-B (Cyt-B) on radiation-induced nucleoplasmic bridges (NPB) in cytokinesis-block assay.Methods Hunan peripheral blood samples were divided into 5 final concentration groups (group 2,4,6,8,10 μg/ml) according to different final concentrations of Cyt-B.Moreover,blood samples were divided into 4 adding time groups (group 0,28,40,44 h) according to different adding times of Cyt-B.Blood samples were irradiated with 0 (sham irradiation) and 2 Gy 60Co-rays in vitro,at a dose rate of 1 Gy/min.A cytokinesis-block assay was carried out to prepare NPB samples.The percentages of mononucleated,binucleated and multinucleated cells,as well as the frequencies of NPB and micronucleus (MN) in binucleated cells were analyzed using an optical microscope.Results Nuclear division index (NDI) and the percentages of binucleated cells increased with increased concentration of Cyt-B,and decreased with delayed adding time of Cyt-B (except group 0 h) in both final concentration groups and adding time groups.After exposed to 2 Gy,NPB frequencies were no significant difference (except group 0 h).MN frequencies had the trend of decreased with the increased concentration of Cyt-B,but no significant difference with adding time of Cyt-B.Conclusions In cytokinesis-block assay,different final concentration and adding time of Cyt-B may induce to the variation of NPB frequencies,but there was no significant difference.Appropriate increased final concentration or ahead adding time of Cyt-B can increase the percentage of binucleated cells that help to improve the efficiency of analysis.

Genotoxicity in lead treated human lymphocytes evaluated by micronucleus and comet assays.

Lead (Pb) which plays a significant role in modern industry is related to a broad range of physiological, biochemical, behavioural and genetical dysfunctions. Its exposure leads to an increased frequency of genetic aberrations in humans. Hence, this study was designed to assess the genotoxic effect of lead acetate at three dosage levels (10, 25 and 50 µg/mL) by employing: the Cytokinesis Block Micronucleus (CBMN) assay and the Comet assay in Peripheral Blood Lymphocyte Cultures. The results of this study revealed an increased level of DNA damage among treated groups. A significant increase in the tail length of comets and other indices was observed at 25 and 50 µg/mL concentrations comparatively. Thus, lead acetate induced single-strand breaks (SSB) and double strand breaks (DSB) in DNA, alkali-labile sites (ALS), oxidative DNA damage as well as DNA-DNA/DNA-protein/DNA-metal cross linking as evidenced by the Comet assay. The chromosome breakage, DNA misrepair, chromosome loss and telomere end fusion were determined by the Micronucleus assay. Micronucleus frequency in treated lymphocytes was significantly higher as compared to controls. Nucleoplasmic bridges increased significantly and Nuclear buds increased at higher two doses only in exposed cultures. Thus, these assays are better indices for lead induced genotoxicity and metal-nucleus interactions.

La proliferación de los miocitos ventriculares del corazón de mamífero adulto: un fenómeno esporádico pero factible / Proliferation of adult mammalian ventricular cardiomyocytes: A sporadic but feasible phenomenon

La proliferación de los miocitos que forman parte de los ventrículos cardíacos del mamífero adulto ha sido descartada por algunos investigadores con el argumento de que estas células están diferenciadas en forma terminal; sin embargo, este dogma ha sido puesto en duda a partir de los hallazgos de otros investigadores quienes han observado que estos miocitos pueden presentar los procesos necesarios para la proliferación, es decir síntesis de ADN, mitosis y citocinesis, cuando el miocardio se daña en forma experimental con estrategias de tipo farmacológico o quirúrgico, o debido a condiciones patológicas relacionadas con el sistema cardiovascular. Esta revisión integra algunos de los trabajos disponibles en la literatura que han evaluado la síntesis del ADN, mitosis y citocinesis en estas células, en el miocardio dañado, para saber si su proliferación puede ser considerada como un fenómeno factible. La revisión concluye con una reflexión sobre las perspectivas del conocimiento generado en esta área de estudio.

Proliferation of adult mammalian ventricular cardiomyocytes has been ruled out by some researchers, who have argued that these cells are terminally differentiated; however, this dogma has been rejected because other researchers have reported that these cells can present the processes necessary to proliferate, that is, DNA synthesis, mitosis and cytokinesis when the heart is damaged experimentally through pharmacological and surgical strategies or due to pathological conditions concerning the cardiovascular system. This review integrates some of the available works in the literature evaluating the DNA synthesis, mitosis and cytokinesis in these myocytes, when the myocardium is damaged, with the purpose of knowing if their proliferation can be considered as a feasible phenomenon. The review is concluded with a reflection about the perspectives of the knowledge generated in this area.

Silencing of KIF14 interferes with cell cycle progression and cytokinesis by blocking the p27(Kip1) ubiquitination pathway in hepatocellular carcinoma

Although it has been suggested that kinesin family member 14 (KIF14) has oncogenic potential in various cancers, including hepatocellular carcinoma (HCC), the molecular mechanism of this potential remains unknown. We aimed to elucidate the role of KIF14 in hepatocarcinogenesis by knocking down KIF14 in HCC cells that overexpressed KIF14. After KIF14 knockdown, changes in tumor cell growth, cell cycle and cytokinesis were examined. We also examined cell cycle regulatory molecules and upstream Skp1/Cul1/F-box (SCF) complex molecules. Knockdown of KIF14 resulted in suppression of cell proliferation and failure of cytokinesis, whereas KIF14 overexpression increased cell proliferation. In KIF14-silenced cells, the levels of cyclins E1, D1 and B1 were profoundly decreased compared with control cells. Of the cyclin-dependent kinase inhibitors, the p27Kip1 protein level specifically increased after KIF14 knockdown. The increase in p27Kip1 was not due to elevation of its mRNA level, but was due to inhibition of the proteasome-dependent degradation pathway. To explore the pathway upstream of this event, we measured the levels of SCF complex molecules, including Skp1, Skp2, Cul1, Roc1 and Cks1. The levels of Skp2 and its cofactor Cks1 decreased in the KIF14 knockdown cells where p27Kip1 accumulated. Overexpression of Skp2 in the KIF14 knockdown cells attenuated the failure of cytokinesis. On the basis of these results, we postulate that KIF14 knockdown downregulates the expression of Skp2 and Cks1, which target p27Kip1 for degradation by the 26S proteasome, leading to accumulation of p27Kip1. The downregulation of Skp2 and Cks1 also resulted in cytokinesis failure, which may inhibit tumor growth. To the best of our knowledge, this is the first report that has identified the molecular target and oncogenic effect of KIF14 in HCC.

Cytogenetic investigation on underground workers in gold mine / 中华放射医学与防护杂志

Objective To investigate the chromosome damage in peripheral lymphocytes of underground gold miners.Methods Conventional method and cytokinesis-block micronuclens assay were used to analyze frequency of chromosome aberrations and micronucleus in peripheral lymphocytes in 58 gold miners,respectively.Results Frequencies of chromosome-type aberrations,ehromatid-type aberrations and total aberrations were higher in the miners than those in the control group(0.72%,0.41%,1.16% vs 0.14%,0.18%,0.33,X2=44.322,9.501,50.476,P＜0.01).Both micronucleated cell rate and micronucleus rate were higher in the miners group than those in the control group(10.8‰ and 11.6‰ vs 8.7‰ and 9.0‰,X2=8.672,12.546,P＜0.01).Frequencies of chromosomal aberrations and micronucleus proportionally increased with underground working years.Compared with those miners who had worked underground 6 years or shorter,both frequencies were statistically higher among the miners who had worked underground for more than 21 years(P＜0.05).No difference was found among other groups of working years(P＞0.05).Compared with the control group,both frequencies increased in the miner group,and the differences were statistically significant(X2=2.395,P＜0.05 for chromosomal aberrations and X2=2.319,P＜0.05,respecfvely).The common types of chromosome aberrations were acentrie fragments,while chromatid break and dicenrics were subordinate.Conclusions Chromosomal damages were observed in the gold workers who exposed high radon in the underground mining.

Microsporogenesis in Brachiaria dictyoneura (Fig. & De Not.) Stapf (Poaceae: Paniceae)

icrosporogenesis was analyzed in five accessions of Brachiaria dictyoneura presenting x = 6 as the basic chromosome number. All accessions were tetraploid (2n = 4x = 24) with chromosome pairing in bi-, tri-, and quadrivalents. The recorded meiotic abnormalities were those typical of polyploids, including precocious chromosome migration to the poles, laggard chromosomes, and micronucleus formation. The frequency of these abnormalities, however, was lower than those reported for other polyploid accessions previously analyzed for other Brachiaria species. Cell fusion and absence of cytokinesis were also recorded in some accessions, leading to restitutional nucleus formation in some cells. Genetically unbalanced microspores, binucleate, and 2n microspores were found among normal meiotic products as results from these abnormalities. The limitation in using these accessions as pollen donor in interspecific crosses with sexual species with x = 7 or x = 9 in breeding programs is discussed.

p21-Activated Kinase 2 Involved in Cytokinesis Independent of Cdc42 During Xenopus Oocyte Maturation / 生物化学与生物物理进展

p21-Activated kinases including p21-activated kinase 2 contributed to the regulation of actin cytoskeleton and cell dynamics. In order to investigate the function of PAK2 on the maturation of Xenopus oocyte, PAK2-NT(PAK2-N-terminal,PAK2-NT) and PAK2-NTm (PAK2-N-terminal mutation) mRNA were microinjected into Xenopus oocyte respectively. Under fluorescent microscopy germinal vesicle breakdown was observed during cytokinesis. To further observe the relationship of oocyte cytokinesis, polar body formation and Cdc42 activity, confocal microscopy with time-lapse was employed . As a result, occurrences of germinal vesicle breakdown in oocytes were similar to those oocytes injected with PAK2-NT mRNA or injected with PAK2-NTm mRNA,but no cytokinesis and polar body formation were observed in oocytes injected with PAK2-NT mRNA or PAK2-NTm mRNA. These results indicated that PAK2 involved in Xenopus oocytes cytokinesis and polar body formation independent of Cdc42 activity.

THE IMPACTS OF FOLIC ACID, RIBOFLAVIN AND MTHFR C677T POLYMORPHISM ON HUMAN LYMPHOCYTES GENOMIC STABILITY / 营养学报

Objective: To explore the comprehensive effects of folic acid (FA), riboflavin (RF) and MTHFR C677T polymorphism on genomic stability. Method: Cytokinesis-block micronucleus assay was used to detect the effects of different concentration combination of FA (20 and 200nmol/L, i.e. LF and HF) , RF (1 and 500 nmol/L, i.e. LR and HR) and MTHFR C677T polymorphism on genomic stability of 9 d cultured human lymphocytes. Results: The genetic damage was significantly higher in LFHR group regardless the genotype (P

Comparison of various procedures in the processing of binucleated-lymphocytes on to glass slide to detect chromosomal breakage.

Binucleated lymphocytes can be screened for micronuclei to assess chromosomal damage. There are various procedures to get slides containing binucleated lymphocytes, that are different in harvesting, fixation, and slide preparation methods. Screening binucleated lymphocytes to find a micronucleus needs at least 800 cells with intact cytoplasm. This study aimed to analyze the various procedures and simplified procedures to know which procedure gave the most abundant binucleated lymphocytes with intact cytoplasm and best staining properties for the purpose of micronucleus scoring. Seven heparinized blood samples were obtained from the Dept. of Obstetrics and gynecology, Faculty of medicine, University of Indonesia, Jakarta. The 7 blood samples were subjected to 17 procedures different in harvesting (with or without washing), slide preparation (smear and spot method, and using a cytocentrifuge), and fixation methods (methanol for 1 minute, methanol brief, methanol/glacial acetic acid 3:1 or 9:1). Our results showed that fixatives containing glacial acetic acid are not suitable for micronucleus test. To generate binucleated lymphocytes with intact cytoplasm as much as possible, the procedure should be conducted without washing steps. Methanol fixation either briefly or 1 minute is preferable, and for the ease of screening cytocentrifuge preparation, followed by spot method is preferable.

Frequency of Micronuclei in Lymphocytes Following Gamma and Fast-neutron Irradiations / 대한치료방사선과학회지

The dose response of the number of micronuclei in cytokinesis-blocked (CB) lymphocytes after in vitro irradiation with -rays and neutrons in the 5 dose ranges was studied for a heterogeneous population of 4 donors. One thousand binucleated cells were systematically scored for micronuclei. Measurements performed after irradiation showed a dose-dependent increase in micronuclei(MN) frequency in each of the doctors studied. The dose-response curves were analyzed by a linear-quadratic model, frequencies per 1000 CB cells were (0.31+/-0.049) D+(0.0022+/-0.0002) D2+(13.19+/-1.854) (r2=1.000, X2=0.7074, p=0.95) following irradiation, and (0.99+/-0.528) D+(0.0093+/-0.0047) D2+(13.31+/-7.309) (r2=0.996, X2=7.6834, p=0.11) following neutrons irradiation (D is irradiation dose in cGy). The relative biological effectiveness (RBE) of neutrons compared with -rays was estimated by best fitting linear-quadratic model. In the micronuclei frequency between 0.05 and 0.8 per cell, the RBE of neutrons was 2.37+/-0.17. Since the MN assay is simple and rapid, it may be a good tool for evaluating the y-ray and neutron response.

Study of the inhibition mechanism of edelfosine on cytokinesis in Schizosaccharomyces pombe / 中国药理学通报

Aim To Study the inhibition mechanism of edelfosine on cytokinesis in Schizosaccharomyces pombe. Methods To observe the inhibition of cytokinesis and growth, the experiments of inhibition of cyto-kinesis and parallel growth were carried out. To explore the inhibition mechanism of edelfosine, the experiment of retransfection of yeast genes was carried out. Results Edelfosine inhibited the cytokinesis of S.pombe in low dosage and cell growth in high dosage. The mid2△、spm1△ and pmp1△ strains were resistant to edelfosine in high dosage. However, these strains retrieved the sensitive to edelfosine in high dosage by retransfected the relevant genes, respectively. A reciprocal action, which was the Mid2p induced the phosphorylated Spm1, while the Pmp1 dephosphorylated Spm1, existed among the Spm1、Mid2 and Pmp1 in S.pombe treated with edelfosine. Conclusion The inhibition of edelfosine on cytokinesis and cell growth due to the effect of Spm1、Mid2 and Pmp1.

FUNCTION OF p21-ACTIVATED KINASE 2 IN XENOPUS OOCYTE CYTOKINESIS / 解剖学报

Objective Study the function of p21-activated kinase 2 in Xenopus oocyte cytokinesis. Methods Xenopus oocyte was used as a model,and MPF activity and PAK2 phosphorylation status were observed during oocyte maturation.The specific inhibitor of PAK2 activity,PAK2-NT(PAK2-N-terminal) was used to microinject into Xenopus oocyte.Under fluorescent microscope germinal vesicle breakdown was observed during cytokinesis.To further observe the changes of F-actin and spindle,laser scanning confocal microscopy with time-lapse method was employed. Results Occurrences of germinal vesicle breakdown in control oocytes was similar to those oocytes injected with PAK2-NT mRNA,but no cytokinesis was observed in oocytes injected with PAK2-NT mRNA.Conclusion These results indicated that PAK2 might involved in Xenopus oocytes cytokinesis.