The Experts below are selected from a list of 74883 Experts worldwide ranked by ideXlab platform
Patricia B. Hoyer - One of the best experts on this subject based on the ideXlab platform.
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Internucleosomal DNA Fragmentation in ovine luteal tissue associated with luteolysis: in vivo and in vitro analyses.
Biology of Reproduction, 1995Co-Authors: Bo R. Rueda, Julie A. Wegner, Samuel L. Marion, Derron D. Wahlen, Patricia B. HoyerAbstract:Internucleosomal DNA Fragmentation, a characteristic of apoptosis, can be visualized with agarose gel electrophoresis as discrete low-molecular-weight DNA fragments (laddering), in multiples of ∼185 bp. GL were collected from superovulated ewes (control) or at 12 h after injection of prostaglandin F 2α (PGF 2α ) on various days after hGG injection. The ability of PGF 2α on Days 8, 10, 12, and 14 (n≥3 per day per treatment) to induce luteal cell DNA Fragmentation was evaluated. DNA was isolated and visualized on agarose gels. No DNA Fragmentation was observed in GL from control ewes on Days 8, 10, or 12. Internucleosomal Fragmentation of DNA (indicative of apoptosis) as well as nonspecific DNA Fragmentation (indicative of non-apoptotic cell death) in GL from Day 14 controls was observed in two of four animals. Additionally, this pattern of DNA Fragmentation was observed in GL from ewes treated with PGF 2α on all days. Evidence of DNA Fragmentation was observed in luteal tissue after dissociation, yet no Fragmentation was observed in unsliced, non-dissociated GL collected from Day 10 control ewes (incubated 4 h), or in sliced, non-incubated GL. Slicing and incubation alone were sufficient to initiate DNA Fragmentation. A variety of approaches were utilized to inhibit DNA Fragmentation. Only the addition of zinc acetate (1 mM) in the incubation medium throughout the 4-h incubation period prevented DNA Fragmentation that was initiated by slicing (p
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internucleosomal DNA Fragmentation in ovine luteal tissue associated with luteolysis in vivo and in vitro analyses
Biology of Reproduction, 1995Co-Authors: Bo R. Rueda, Julie A. Wegner, Samuel L. Marion, Derron D. Wahlen, Patricia B. HoyerAbstract:Internucleosomal DNA Fragmentation, a characteristic of apoptosis, can be visualized with agarose gel electrophoresis as discrete low-molecular-weight DNA fragments (laddering), in multiples of ∼185 bp. GL were collected from superovulated ewes (control) or at 12 h after injection of prostaglandin F 2α (PGF 2α ) on various days after hGG injection. The ability of PGF 2α on Days 8, 10, 12, and 14 (n≥3 per day per treatment) to induce luteal cell DNA Fragmentation was evaluated. DNA was isolated and visualized on agarose gels. No DNA Fragmentation was observed in GL from control ewes on Days 8, 10, or 12. Internucleosomal Fragmentation of DNA (indicative of apoptosis) as well as nonspecific DNA Fragmentation (indicative of non-apoptotic cell death) in GL from Day 14 controls was observed in two of four animals. Additionally, this pattern of DNA Fragmentation was observed in GL from ewes treated with PGF 2α on all days. Evidence of DNA Fragmentation was observed in luteal tissue after dissociation, yet no Fragmentation was observed in unsliced, non-dissociated GL collected from Day 10 control ewes (incubated 4 h), or in sliced, non-incubated GL. Slicing and incubation alone were sufficient to initiate DNA Fragmentation. A variety of approaches were utilized to inhibit DNA Fragmentation. Only the addition of zinc acetate (1 mM) in the incubation medium throughout the 4-h incubation period prevented DNA Fragmentation that was initiated by slicing (p<0.05). There appear therefore, to be one or more intraluteal factors that directly initiate DNA Fragmentation associated with cell death in luteolysis. This Fragmentation appears to a variable degree in Day 14 animals (at the onset of luteolysis) and can be induced by injection of animals with PGF 2a
Ming Xu - One of the best experts on this subject based on the ideXlab platform.
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DNA Fragmentation in Mammalian Apoptosis and Tissue Homeostasis
Molecular Mechanisms of Programmed Cell Death, 2020Co-Authors: Ming Xu, Jianhua ZhangAbstract:Apoptosis is a highly regulated physiological process critical in development and tissue homeostasis. Abnormal apoptosis can lead to disease conditions including neurodegeneration, autoimmunity and cancer. DNA Fragmentation is an integral part of apoptosis and has long been suspected to be of critical importance in cleaning up potentially antigenic DNA and genetic materials capable of inducing neoplasmic transformation in neighboring cells. Direct evidence for this role of DNA Fragmentation in apoptosis however, is still lacking. The identification of a heterodimeric DNA Fragmentation factor composed of a 45 and 40 kDa subunit (termed DFF45 and DFF40, or ICAD for Inhibitor of Caspase Activated DNAse and CAD for Caspase Activated DNAse, respectively) as well as endonuclease G (EndoG) provides a timely opportunity for addressing the physiological significance of DNA Fragmentation in apoptosis and tissue homeostasis. We previously generated a DFF45 mutant mouse in which the DFF activity is abolished. We found that DFF45-deficient thymocytes are resistant to DNA Fragmentation both in vivo and in cultured primary cells exposed to various apoptotic stimuli. Interestingly, DFF45-deficient thymocytes and mouse embryonic fibroblasts (MEFs) are partially resistant to apoptosis in response to several apoptotic-inducing agents. There are more granule cells in the dentate gyrus of the hippocampal formation in DFF45 mutant mice than in normal control mice. This increased neuronal cell number correlates with enhanced spatial and non-spatial learning and memory retention in DFF45 mutant mice compared with control mice. These results suggest that DFF45 is critical for DNA Fragmentation and a deficiency in DFF45 can affect timely completion of apoptosis and consequently tissue homeostasis and proper cellular function. Likely due to the unaffected EndoG activity however, residual DNA Fragmentation can be found in DFF45-deficient splenocytes and MEFs. In a collaborative effort, we are generating EndoG mutant mice and mice with combined deficiencies of DFF45 and EndoG to investigate how DFF and EndoG jointly function to insure proper apoptosis and tissue homeostasis.
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Apoptotic DNA Fragmentation and tissue homeostasis
Trends in Cell Biology, 2002Co-Authors: Jianhua Zhang, Ming XuAbstract:Abstract DNA Fragmentation is a hallmark of apoptosis. The tightly controlled activation of the apoptosis-specific endonucleases provides an effective means to ensure the removal of unwanted DNA and the timely completion of apoptosis. Over the past several years, crucial progress has been made in identifying the long-awaited apoptotic endonucleases, and their importance in tissue homeostasis is beginning to unfold. Here, we focus on the most recent discoveries about the functions and mechanisms of these endonucleases in the context of apoptosis. We also discuss consequences that defective DNA Fragmentation might have for tissue homeostasis and disease development.
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resistance to DNA Fragmentation and chromatin condensation in mice lacking the DNA Fragmentation factor 45
Proceedings of the National Academy of Sciences of the United States of America, 1998Co-Authors: Jianhua Zhang, David C Scherer, L Van Kaer, Xiaodong Wang, Ming XuAbstract:The DNA Fragmentation factor 45 (DFF45) is a subunit of a heterodimeric nuclease complex critical for the induction of DNA Fragmentation in vitro. To understand the in vivo role of DFF45 in programmed cell death, we generated DFF45 mutant mice. DNA Fragmentation activity is completely abolished in cell extracts from DFF45 mutant tissues. In response to apoptotic stimuli, splenocytes, thymocytes, and granulocytes from DFF45 mutant mice are resistant to DNA Fragmentation, and splenocytes and thymocytes are also resistant to chromatin condensation. Nevertheless, development of the immune system in the DFF45 mutant mice is normal. These results demonstrate that DFF45 is critical for the induction of DNA Fragmentation and chromatin condensation in vivo, but is not required for normal immune system development.
Jianhua Zhang - One of the best experts on this subject based on the ideXlab platform.
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DNA Fragmentation in Mammalian Apoptosis and Tissue Homeostasis
Molecular Mechanisms of Programmed Cell Death, 2020Co-Authors: Ming Xu, Jianhua ZhangAbstract:Apoptosis is a highly regulated physiological process critical in development and tissue homeostasis. Abnormal apoptosis can lead to disease conditions including neurodegeneration, autoimmunity and cancer. DNA Fragmentation is an integral part of apoptosis and has long been suspected to be of critical importance in cleaning up potentially antigenic DNA and genetic materials capable of inducing neoplasmic transformation in neighboring cells. Direct evidence for this role of DNA Fragmentation in apoptosis however, is still lacking. The identification of a heterodimeric DNA Fragmentation factor composed of a 45 and 40 kDa subunit (termed DFF45 and DFF40, or ICAD for Inhibitor of Caspase Activated DNAse and CAD for Caspase Activated DNAse, respectively) as well as endonuclease G (EndoG) provides a timely opportunity for addressing the physiological significance of DNA Fragmentation in apoptosis and tissue homeostasis. We previously generated a DFF45 mutant mouse in which the DFF activity is abolished. We found that DFF45-deficient thymocytes are resistant to DNA Fragmentation both in vivo and in cultured primary cells exposed to various apoptotic stimuli. Interestingly, DFF45-deficient thymocytes and mouse embryonic fibroblasts (MEFs) are partially resistant to apoptosis in response to several apoptotic-inducing agents. There are more granule cells in the dentate gyrus of the hippocampal formation in DFF45 mutant mice than in normal control mice. This increased neuronal cell number correlates with enhanced spatial and non-spatial learning and memory retention in DFF45 mutant mice compared with control mice. These results suggest that DFF45 is critical for DNA Fragmentation and a deficiency in DFF45 can affect timely completion of apoptosis and consequently tissue homeostasis and proper cellular function. Likely due to the unaffected EndoG activity however, residual DNA Fragmentation can be found in DFF45-deficient splenocytes and MEFs. In a collaborative effort, we are generating EndoG mutant mice and mice with combined deficiencies of DFF45 and EndoG to investigate how DFF and EndoG jointly function to insure proper apoptosis and tissue homeostasis.
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Apoptotic DNA Fragmentation and tissue homeostasis
Trends in Cell Biology, 2002Co-Authors: Jianhua Zhang, Ming XuAbstract:Abstract DNA Fragmentation is a hallmark of apoptosis. The tightly controlled activation of the apoptosis-specific endonucleases provides an effective means to ensure the removal of unwanted DNA and the timely completion of apoptosis. Over the past several years, crucial progress has been made in identifying the long-awaited apoptotic endonucleases, and their importance in tissue homeostasis is beginning to unfold. Here, we focus on the most recent discoveries about the functions and mechanisms of these endonucleases in the context of apoptosis. We also discuss consequences that defective DNA Fragmentation might have for tissue homeostasis and disease development.
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DNA Fragmentation in apoptosis
Cell Research, 2000Co-Authors: Jianhua Zhang, Xu MAbstract:Cleavage of chromosomal DNA into oligonucleosomal size fragments is an integral part of apoptosis. Elegant biochemical work identified the DNA Fragmentation factor (DFF) as a major apoptotic endonuclease for DNA Fragmentation in vitro. Genetic studies in mice support the importance of DFF in DNA Fragmentation and possibly in apoptosis in vivo. Recent work also suggests the existence of additional endonucleases for DNA degradation. Understanding the roles of individual endonucleases in apoptosis, and how they might coordinate to degrade DNA in different tissues during normal development and homeostasis, as well as in various diseased states, will be a major research focus in the near future.
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resistance to DNA Fragmentation and chromatin condensation in mice lacking the DNA Fragmentation factor 45
Proceedings of the National Academy of Sciences of the United States of America, 1998Co-Authors: Jianhua Zhang, David C Scherer, L Van Kaer, Xiaodong Wang, Ming XuAbstract:The DNA Fragmentation factor 45 (DFF45) is a subunit of a heterodimeric nuclease complex critical for the induction of DNA Fragmentation in vitro. To understand the in vivo role of DFF45 in programmed cell death, we generated DFF45 mutant mice. DNA Fragmentation activity is completely abolished in cell extracts from DFF45 mutant tissues. In response to apoptotic stimuli, splenocytes, thymocytes, and granulocytes from DFF45 mutant mice are resistant to DNA Fragmentation, and splenocytes and thymocytes are also resistant to chromatin condensation. Nevertheless, development of the immune system in the DFF45 mutant mice is normal. These results demonstrate that DFF45 is critical for the induction of DNA Fragmentation and chromatin condensation in vivo, but is not required for normal immune system development.
Bo R. Rueda - One of the best experts on this subject based on the ideXlab platform.
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Internucleosomal DNA Fragmentation in ovine luteal tissue associated with luteolysis: in vivo and in vitro analyses.
Biology of Reproduction, 1995Co-Authors: Bo R. Rueda, Julie A. Wegner, Samuel L. Marion, Derron D. Wahlen, Patricia B. HoyerAbstract:Internucleosomal DNA Fragmentation, a characteristic of apoptosis, can be visualized with agarose gel electrophoresis as discrete low-molecular-weight DNA fragments (laddering), in multiples of ∼185 bp. GL were collected from superovulated ewes (control) or at 12 h after injection of prostaglandin F 2α (PGF 2α ) on various days after hGG injection. The ability of PGF 2α on Days 8, 10, 12, and 14 (n≥3 per day per treatment) to induce luteal cell DNA Fragmentation was evaluated. DNA was isolated and visualized on agarose gels. No DNA Fragmentation was observed in GL from control ewes on Days 8, 10, or 12. Internucleosomal Fragmentation of DNA (indicative of apoptosis) as well as nonspecific DNA Fragmentation (indicative of non-apoptotic cell death) in GL from Day 14 controls was observed in two of four animals. Additionally, this pattern of DNA Fragmentation was observed in GL from ewes treated with PGF 2α on all days. Evidence of DNA Fragmentation was observed in luteal tissue after dissociation, yet no Fragmentation was observed in unsliced, non-dissociated GL collected from Day 10 control ewes (incubated 4 h), or in sliced, non-incubated GL. Slicing and incubation alone were sufficient to initiate DNA Fragmentation. A variety of approaches were utilized to inhibit DNA Fragmentation. Only the addition of zinc acetate (1 mM) in the incubation medium throughout the 4-h incubation period prevented DNA Fragmentation that was initiated by slicing (p
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internucleosomal DNA Fragmentation in ovine luteal tissue associated with luteolysis in vivo and in vitro analyses
Biology of Reproduction, 1995Co-Authors: Bo R. Rueda, Julie A. Wegner, Samuel L. Marion, Derron D. Wahlen, Patricia B. HoyerAbstract:Internucleosomal DNA Fragmentation, a characteristic of apoptosis, can be visualized with agarose gel electrophoresis as discrete low-molecular-weight DNA fragments (laddering), in multiples of ∼185 bp. GL were collected from superovulated ewes (control) or at 12 h after injection of prostaglandin F 2α (PGF 2α ) on various days after hGG injection. The ability of PGF 2α on Days 8, 10, 12, and 14 (n≥3 per day per treatment) to induce luteal cell DNA Fragmentation was evaluated. DNA was isolated and visualized on agarose gels. No DNA Fragmentation was observed in GL from control ewes on Days 8, 10, or 12. Internucleosomal Fragmentation of DNA (indicative of apoptosis) as well as nonspecific DNA Fragmentation (indicative of non-apoptotic cell death) in GL from Day 14 controls was observed in two of four animals. Additionally, this pattern of DNA Fragmentation was observed in GL from ewes treated with PGF 2α on all days. Evidence of DNA Fragmentation was observed in luteal tissue after dissociation, yet no Fragmentation was observed in unsliced, non-dissociated GL collected from Day 10 control ewes (incubated 4 h), or in sliced, non-incubated GL. Slicing and incubation alone were sufficient to initiate DNA Fragmentation. A variety of approaches were utilized to inhibit DNA Fragmentation. Only the addition of zinc acetate (1 mM) in the incubation medium throughout the 4-h incubation period prevented DNA Fragmentation that was initiated by slicing (p<0.05). There appear therefore, to be one or more intraluteal factors that directly initiate DNA Fragmentation associated with cell death in luteolysis. This Fragmentation appears to a variable degree in Day 14 animals (at the onset of luteolysis) and can be induced by injection of animals with PGF 2a
Gary D Smith - One of the best experts on this subject based on the ideXlab platform.
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Effects of semen storage and separation techniques on sperm DNA Fragmentation
Fertility and Sterility, 2010Co-Authors: Robert E Jackson, Charles L. Bormann, Pericles A. Hassun, André M. Rocha, Eduardo L A Motta, Paulo Cesar Serafini, Gary D SmithAbstract:Objective: To determine the effect of semen storage and separation techniques on sperm DNA Fragmentation. Design: Controlled clinical study. Setting: An assisted reproductive technology laboratory. Patient(s): Thirty normoozospermic semen samples obtained from patients undergoing infertility evaluation. Intervention(s): One aliquot from each sample was immediately prepared (control) for the sperm chromatin dispersion assay (SCD). Aliquots used to assess storage techniques were treated in the following ways: snap frozen by liquid nitrogen immersion, slow frozen with Tris-yolk buffer and glycerol, kept on ice for 24 hours or maintained at room temperature for 4 and 24 hours. Aliquots used to assess separation techniques were processed by the following methods: washed and centrifuged in media, swim-up from washed sperm pellet, density gradient separation, density gradient followed by swim-up. DNA integrity was then measured by SCD. Main Outcome Measure(s): DNA Fragmentation as measured by SCD. Result(s): There was no significant difference in Fragmentation among the snap frozen, slow frozen, and wet-ice groups. Compared to other storage methods short-term storage at room temperature did not impact DNA Fragmentation yet 24 hours storage significantly increased Fragmentation. Swim-up, density gradient and density gradient/swim-up had significantly reduced DNA Fragmentation levels compared with washed semen. Postincubation, density gradient/swim-up showed the lowest Fragmentation levels. Conclusion(s): The effect of sperm processing methods on DNA Fragmentation should be considered when selecting storage or separation techniques for clinical use. Copyright © 2010 American Society for Reproductive Medicine, Published by Elsevier Inc.