scholarly journals Stage and season effects on cell cycle and apoptotic activities of germ cells and Sertoli cells during spermatogenesis in the spiny dogfish (Squalus acanthias)

Reproduction ◽  
2005 ◽  
Vol 129 (1) ◽  
pp. 89-102 ◽  
Author(s):  
L M McClusky
Keyword(s):  
Cell Cycle ◽  
Sertoli Cell ◽  
Early Stage ◽  
Squalus Acanthias ◽  
Nuclear Antigen ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Dependent Manner ◽  
Testicular Cells ◽  
Germinal Zone ◽  
Proliferating Cell

To understand the processes involved in the spatial and temporal maturation of testicular cells in Squalus acanthias, we used standard morphometry, proliferating-cell nuclear antigen (PCNA) and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labelling (TUNEL) immunohistochemistry. Except for immature spermatocysts (germinal zone, GZ; early-stage pre-meiotic, E-PrM), the number of cysts in all subsequent stages and the total number of cysts in the spermatogenic progression varied seasonally. The spermatogenic cycle spans about 2 years and is interrupted by germcell clone deletion via apoptosis at the mitosis–meiosis transition in April/May, manifesting as a zone of degeneration (ZD). Rate of displacement of the ZD across the testis diameter indicates that late-stage premeiotic (L-PrM) generations 12–13 require 9–10 months to reach the mature-spermatid stage. Also, the number of cysts completing spermatogenesis is approximately 4–5-fold less than the number that entered spermatogenesis proper 2 years earlier. Pronounced gonocytogenesis in the germinal ridge was coincident with ZD formation in April/May, but it was absent in the fall when mature spermatogonial and meiotic activities had resumed. Whereas strong Sertoli cell PCNA immunoreactivity dominated the GZ cyst cell-cycle activities throughout the year, except during the spring/summer months, the spermatogonial- and Sertoli-cell PCNA indices in E-PrM cysts were inversely related. PCNA immunoreactivity in spermatocytes was seasonal and dependent on the stage of meiosis. TUNEL labelling was limited to spermatogonia and increased stage-dependently in the PrM region (L-PrM = mid-stage PrM ≫E-PrM ≫GZ), correlating with ZD formation, in a season-dependent manner. Results imply that effects of normal regulatory factors in Squalus are stage- and process-specific.

Demonstration of cell cycle kinetics in thyroid primary culture by immunostaining of proliferating cell nuclear antigen: differences in cyclic AMP-dependent and -independent mitogenic stimulations

1993 ◽  
Vol 105 (1) ◽  
pp. 69-80 ◽  
Author(s):  
M. Baptist ◽  
J.E. Dumont ◽  
P.P. Roger
Keyword(s):  
Cell Cycle ◽  
Dna Synthesis ◽  
Primary Culture ◽  
Proliferating Cell Nuclear Antigen ◽  
Cell Cycle Progression ◽  
Nuclear Antigen ◽  
Major Influence ◽  
Cell Cycle Kinetics ◽  
Experimental Conditions ◽  
Proliferating Cell

In this study, experimental conditions are described that allowed us to follow the fate of the DNA polymerase delta-associated proliferating cell nuclear antigen (PCNA), by immunolabeling during the overall cell cycle. Differences in subcellular localization or the presence of PCNA allowed us to identify each phase of the cell cycle. Using these cell cycle markers in dog thyroid epithelial cells in primary culture, we found unexpected differences in cell cycle kinetics, in response to stimulations through cAMP-dependent and cAMP-independent pathways. These provide a new dimension to the view that the two pathways are largely separate, but co-operate on DNA synthesis initiation. More precisely, thyrotropin (TSH), acting via cAMP, exerts a potent triggering effect on DNA synthesis, associated with a precocious induction of PCNA appearance. This constitutes the major influence of TSH (cAMP) in determining cell cycle progression, which is only partly moderated by TSH-dependent lengthening of S- and G2-phases.

scholarly journals An evaluation of antioxidant effects on recovery from postischemic acute renal failure.

1994 ◽  
Vol 4 (8) ◽  
pp. 1588-1597
Author(s):  
R A Zager ◽  
S M Fuerstenberg ◽  
P H Baehr ◽  
D Myerson ◽  
B Torok-Storb
Keyword(s):  
Renal Failure ◽  
Acute Renal Failure ◽  
Dna Fragmentation ◽  
Proliferating Cell Nuclear Antigen ◽  
Antigen Expression ◽  
Nuclear Antigen ◽  
Terminal Deoxynucleotidyl Transferase ◽  
Tubular Necrosis ◽  
Proliferating Cell

Xanthine oxidase (XO) activity and hydroxyl radical (.OH) formation are widely proposed mediators of renal reperfusion injury, potentially altering the severity of, and recovery from, postischemic acute renal failure. The goal of this study was to ascertain whether combination XO inhibitor (oxypurinol) and .OH scavenger (Na benzoate) therapy, given at the time of renal ischemia, alters the extent of: (1) tubular necrosis and filtration failure; (2) DNA fragmentation/apoptosis (assessed in situ by terminal deoxynucleotidyl transferase reactivity); (3) early tubular regenerative responses (proliferating cell nuclear antigen expression; (3H)thymidine incorporation); and (4) the rate and/or degree of functional and morphologic repair. The effects of XO inhibition, .OH scavengers, and "catalytic" iron (FeSO4) on human proximal tubular cell proliferation in vitro were also assessed with a newly established cell line (HK-2). Male Sprague-Dawley rats were subjected to 35 min of bilateral renal arterial occlusion with or without oxypurinol/benzoate therapy. These agents did not alter the extent of tubular necrosis or filtration failure, proliferating cell nuclear antigen expression or thymidine incorporation, or the rate/extent of renal functional/morphologic repair. DNA fragmentation did not precede tubular necrosis, and it was unaffected by antioxidant therapy. By 5 days postischemia, both treatment groups demonstrated regenerating epithelial fronds that protruded into the lumina. These structures contained terminal deoxynucleotidyl transferase-reactive, but morphologically intact, cells, suggesting the presence of apoptosis. Oxypurinol and .OH scavengers (benzoate; dimethylthiourea) suppressed in vitro tubular cell proliferation; conversely, catalytic Fe had a growth-stimulatory effect. These results suggest that: (1) XO inhibition/.OH scavenger therapy has no discernible net effect on postischemic acute renal failure; (2) DNA fragmentation does not precede tubular necrosis, suggesting that it is not a primary mediator of ischemic cell death; and (3) antioxidants can be antiproliferative for human tubular cells, possibly mitigating their potential beneficial effects.

scholarly journals The caspase-dependent apoptosis gradient in the testis of the blue shark, Prionace glauca

Reproduction ◽  
2013 ◽  
Vol 145 (3) ◽  
pp. 297-310 ◽  
Author(s):  
Leon M McClusky
Keyword(s):  
Sertoli Cell ◽  
Caspase 3 ◽  
Recovery Phase ◽  
Nuclear Antigen ◽  
Death Process ◽  
Type B ◽  
Blue Shark ◽  
Testicular Morphology ◽  
Further Development ◽  
Proliferating Cell

The severe degenerative phenomena that characterises spermatogenesis in mating blue sharks involves spatially separated germ cell and Sertoli cell apoptosis. Unlike that observed in multilayered type B spermatogonial and spermatocyte cysts caspase-3-dependent apoptosis of single and multinucleate type B spermatogonia in one to three spermatogonial layered cysts resulted in their complete fragmentation, delayed phagocytic removal and displacement of the apoptotic bodies towards the perilumenar Sertoli nuclei. Changes were observed in the immunostaining patterns of proliferating cell nuclear antigen (PCNA), including subtle changes in cytoplasmic and overall intense immunostaining, labelled single and multinucleate cell (MNC) apoptotic spermatogonial masses in premeiotic cysts in different stages of the protracted death process. Initial massive MNC formation at the mitosis–meiosis transition eventually left its imprint in the spermatogenic sequence in the form of vacuolated areas in the affected and subsequent stages. Some of the latter attempted further developmental advance but eventually degenerated. The observed higher PCNA index of spermatogonia in vacuolated testes compared to testes with the MNC type of degeneration indicated that the former testicular morphology represented, in essence, the recovery phase from the pronounced MNC death earlier. Events culminating in the eventual apoptotic demise of the Sertoli cells themselves included the abortion of further development (presumably due to a suboptimal Sertoli:germ cell ratio) of those germ cells left over from the wave of MNC death that swept the cysts. Eventually the Sertoli-cell-only cysts became apoptotic as they were engulfed by the infiltrating lymphomyeloid cells from the epigonal organ associated with the mature pole of the testis.

scholarly journals Proliferating Cell Nuclear Antigen as the Cell Cycle Sensor for an HLA-Derived Peptide Blocking T Cell Proliferation

2000 ◽  
Vol 164 (12) ◽  
pp. 6188-6192 ◽  
Author(s):  
Xuefeng Ling ◽  
Salar Kamangar ◽  
Michelle L. Boytim ◽  
Zvi Kelman ◽  
Philip Huie ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
T Cell ◽  
Proliferating Cell Nuclear Antigen ◽  
Nuclear Antigen ◽  
T Cell Proliferation ◽  
Proliferating Cell

scholarly journals Differential Roles for Cyclin-Dependent Kinase Inhibitors p21 and p16 in the Mechanisms of Senescence and Differentiation in Human Fibroblasts

1999 ◽  
Vol 19 (3) ◽  
pp. 2109-2117 ◽  
Author(s):  
Gretchen H. Stein ◽  
Linda F. Drullinger ◽  
Alexandre Soulard ◽  
Vjekoslav Dulić
Keyword(s):  
Cell Cycle ◽  
Cyclin D1 ◽  
Cell Cycle Arrest ◽  
Early Stage ◽  
Cyclin E ◽  
Human Fibroblasts ◽  
Senescent Cell ◽  
Nuclear Antigen ◽  
Cyclin Dependent Kinase ◽  
Cycle Arrest

ABSTRACT The irreversible G1 arrest in senescent human diploid fibroblasts is probably caused by inactivation of the G1cyclin–cyclin-dependent kinase (Cdk) complexes responsible for phosphorylation of the retinoblastoma protein (pRb). We show that the Cdk inhibitor p21Sdi1,Cip1,Waf1, which accumulates progressively in aging cells, binds to and inactivates all cyclin E-Cdk2 complexes in senescent cells, whereas in young cells only p21-free Cdk2 complexes are active. Furthermore, the senescent-cell-cycle arrest occurs prior to the accumulation of the Cdk4-Cdk6 inhibitor p16Ink4a, suggesting that p21 may be sufficient for this event. Accordingly, cyclin D1-associated phosphorylation of pRb at Ser-780 is lacking even in newly senescent fibroblasts that have a low amount of p16. Instead, the cyclin D1-Cdk4 and cyclin D1-Cdk6 complexes in these cells are associated with an increased amount of p21, suggesting that p21 may be responsible for inactivation of both cyclin E- and cyclin D1-associated kinase activity at the early stage of senescence. Moreover, even in the late stage of senescence when p16 is high, cyclin D1-Cdk4 complexes are persistent, albeit reduced by ≤50% compared to young cells. We also provide new evidence that p21 may play a role in inactivation of the DNA replication factor proliferating cell nuclear antigen during early senescence. Finally, because p16 accumulates in parallel with the increases in senescence-associated β-Gal activity and cell volume that characterize the senescent phenotype, we suggest that p16 upregulation may be part of a differentiation program that is turned on in senescent cells. Since p21 decreases after senescence is achieved, this upregulation of p16 may be essential for maintenance of the senescent-cell-cycle arrest.

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