In situ study of chorion gene amplification in ovarian follicle cells ofDrosophila nasuta

1990 ◽  
Vol 15 (2) ◽  
pp. 99-105
Author(s):  
P. K. Tiwapi ◽  
S. C. Lakhotia
Keyword(s):  
Gene Amplification ◽  
Ovarian Follicle ◽  
Follicle Cells ◽  
In Situ Study

scholarly journals Transcriptional Repressor Functions of Drosophila E2F1 and E2F2 Cooperate To Inhibit Genomic DNA Synthesis in Ovarian Follicle Cells

2003 ◽  
Vol 23 (6) ◽  
pp. 2123-2134 ◽  
Author(s):  
Pelin Cayirlioglu ◽  
William O. Ward ◽  
S. Catherine Silver Key ◽  
Robert J. Duronio
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Dna Synthesis ◽  
Gene Amplification ◽  
Cell Cycle Progression ◽  
Ovarian Follicle ◽  
Cell Cycle Control ◽  
Control Cell ◽  
Follicle Cell ◽  
Follicle Cells

ABSTRACT Individual members of the E2F/DP protein family control cell cycle progression by acting predominantly as an activator or repressor of transcription. In Drosophila melanogaster the E2f1, E2f2, Dp, and Rbf1 genes all contribute to replication control in ovarian follicle cells, which become 16C polyploid and subsequently undergo chorion gene amplification late in oogenesis. Mutation of E2f2, Dp, or Rbf1 causes ectopic DNA replication throughout the follicle cell genome during gene amplification cycles. Here we show by both reverse transcription-PCR and DNA microarray analysis that the transcripts of prereplication complex (pre-RC) genes are elevated compared to the wild type in E2f2, Dp, and Rbf1 mutant follicle cells. For some genes the magnitude of this transcriptional derepression is greater in Rbf1 than in E2f2 mutants. These differences correlate with differences in the magnitude of the replication defects in follicle cells, which attain an inappropriate 32C DNA content in both Rbf1 and Dp mutants but not in E2f2 mutants. The ectopic genomic replication of E2f2 mutant follicle cells can be suppressed by reducing the Orc2, Orc5, or Mcm2 gene dose by half, indicating that small changes in pre-RC gene expression can affect DNA synthesis in these cells. We conclude that RBF1 forms complexes with both E2F1/DP and E2F2/DP that cooperate to repress the expression of pre-RC genes, which helps confine DNA synthesis to sites of gene amplification. In contrast, E2F1 and E2F2 repressors function redundantly for some genes in the embryo. Thus, the relative functional contributions of E2F1 and E2F2 to gene expression and cell cycle control depends on the developmental context.

scholarly journals Epigenetic regulation affects fertility in Drosophila: toward the production of infertile models

2018 ◽  
Author(s):  
Hidetsugu Kohzaki ◽  
Maki Asano ◽  
Yota Murakami ◽  
Alexander Mazo
Keyword(s):  
Dna Replication ◽  
Gene Amplification ◽  
Epigenetic Regulation ◽  
Origin Recognition Complex ◽  
Ovarian Follicle ◽  
Gene Clusters ◽  
Follicle Cells ◽  
Female Sterility ◽  
Ovary Development ◽  
Replication Machinery

AbstractWe have revealed that the chorion gene clusters amplify by repeatedly initiating DNA replication from chorion gene amplification origins in the response to developmental signals, through the transcription factors in Drosophila ovarian follicle cells. Orc1, Orc2, and Cdc6 are forms of DNA replication machinery, which are conserved from yeast to humans; and Orc1 and Orc2 mutants are lethal. Overexpression of Orc1 or Orc2 (subunits of the origin recognition complex) led to female sterility, but overexpression of Cdc6 (an Orc family member) or GFP did not. We propose that DNA replication machinery contributes to development.Recently, we found that H3K4 was trimethylated at chorion gene amplification origins, but not at the Act1 locus. Overexpression of Lsd1H3K4 dimethylase and Lid H3K4 trimethylase are female sterile but not a Lid mutant. These results showed that epigenetic regulation affected fertility. Screening strategies using Drosophila flies could also lead to the development of drugs that reduce sterility and epigenetic effects related histone modification.Summary statementThere are approximately 470,000 infertile individuals in Japan. We knockowned the prereplicative complex components and demethlases during Drosophila ovary development. In these drospohila, we could be the model of infertile.

scholarly journals Drosophila E2f2 promotes the conversion from genomic DNA replication to gene amplification in ovarian follicle cells

Development ◽  
2001 ◽  
Vol 128 (24) ◽  
pp. 5085-5098 ◽  
Author(s):  
Pelin Cayirlioglu ◽  
Peter C. Bonnette ◽  
M. Ryan Dickson ◽  
Robert J. Duronio
Keyword(s):  
Dna Replication ◽  
Dna Synthesis ◽  
Gene Amplification ◽  
Genomic Dna ◽  
Essential Gene ◽  
Ovarian Follicle ◽  
Follicle Cell ◽  
Follicle Cells ◽  
Female Sterility ◽  
Wild Type

Drosophila contains two members of the E2F transcription factor family (E2f and E2f2), which controls the expression of genes that regulate the G1-S transition of the cell cycle. Previous genetic analyses have indicated that E2f is an essential gene that stimulates DNA replication. We show that loss of E2f2 is viable, but causes partial female sterility associated with changes in the mode of DNA replication in the follicle cells that surround the developing oocyte. Late in wild-type oogenesis, polyploid follicle cells terminate a program of asynchronous endocycles in which the euchromatin is entirely replicated, and then confine DNA synthesis to the synchronous amplification of specific loci, including two clusters of chorion genes that encode eggshell proteins. E2f2 mutant follicle cells terminate endocycles on schedule, but then fail to confine DNA synthesis to sites of gene amplification and inappropriately begin genomic DNA replication. This ectopic DNA synthesis does not represent a continuation of the endocycle program, as the cells do not complete an entire additional S phase. E2f2 mutant females display a 50% reduction in chorion gene amplification, and lay poorly viable eggs with a defective chorion. The replication proteins ORC2, CDC45L and ORC5, which in wild-type follicle cell nuclei localize to sites of gene amplification, are distributed throughout the entire follicle cell nucleus in E2f2 mutants, consistent with their use at many genomic replication origins rather than only at sites of gene amplification. RT-PCR analyses of RNA purified from E2f2 mutant follicle cells indicate an increase in the level of Orc5 mRNA relative to wild type. These data indicate that E2f2 functions to inhibit widespread genomic DNA synthesis in late stage follicle cells, and may do so by repressing the expression of specific components of the replication machinery.

A PILOT STUDY OF HER-2/NEU GENE AMPLIFICATION ASSESSED BY FLUORESCENCE IN SITU HYBRIDIZATION (FISH) IN GASTRIC CANCER

2014 ◽  
pp. 15-20
Author(s):  
Van Huy Tran ◽  
Thi Minh Thi Ha ◽  
Trung Nghia Van ◽  
Viet Nhan Nguyen ◽  
Phan Tuong Quynh Le ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
In Situ Hybridization ◽  
Fluorescence In Situ Hybridization ◽  
Cancer Patients ◽  
Gene Amplification ◽  
Cancer Tissue ◽  
Tissue Samples ◽  
Her 2 ◽  
Gastric Cancer Patients

Background: HER-2/neu is a predictive biomarker for treatment of gastric cancer using trastuzumab in combination with chemotherapy. This study aimed to evaluate the status of HER-2/neu gene amplification using fluorescence in situ hybridization (FISH) in gastric cancer. Patients and methods: thirty six gastric cancer patients were assessed HER-2/neu gene amplification by FISH using PathVysionTM HER-2 DNA Probe kit (including HER-2/neu probe and CEP-17 probe) with biopsy and surgical specimens. Results: The HER-2/neu gene amplification was observed in three cases (8.3%), the HER-2/neu gene amplification rate in Lauren’s intestinal-type and diffuse-type were 11.8% and 5.2%, respectively. Conclusion: We applied successfully FISH technique with gastric cancer tissue samples. This technique could be performed as routine test in gastric cancer in order to select patients that benefit from trastuzumab in combination with chemotherapy.

scholarly journals In situ study of microstructure in phase transformation of pipe line steel

2021 ◽  
Vol 27 (S1) ◽  
pp. 1554-1555
Author(s):  
Chen Gu ◽  
Nabil Bassim ◽  
Hatem Zurob
Keyword(s):  
Phase Transformation ◽  
In Situ Study ◽  
Line Steel ◽  
Pipe Line
Sign in / Sign up

Export Citation Format

Share Document