title: The apoptotic function analysis of p53, Apaf1, Caspase3 and Caspase7 during the spermatogenesis of the Chinese fire-bellied newt Cynops orientalis.
abstract: BACKGROUND
  Spontaneous and stress-induced germ cell apoptosis during spermatogenesis of multicellular organisms have been investigated broadly in mammals. Spermatogenetic process in urodele amphibians was essentially like that in mammals in spite of morphological differences; however, the mechanism of germ cell apoptosis in urodele amphibians remains unknown. The Chinese fire-belly newt, Cynops orientalis, was an excellent organism for studying germ cell apoptosis due to its sensitiveness to temperature, strong endurance of starvation, and sensitive skin to heavy metal exposure.
  
  
  RESULTS
  TUNEL result showed that spontaneous germ cell apoptosis took place in normal newt, and severe stress-induced apoptosis occurred to spermatids and sperm in response to heat shock (40°C 2 h), cold exposure (4°C 12 h), cadmium exposure (Cd 36 h), and starvation stress. Quantitative reverse transcription polymerase chain reactions (qRT-PCR) showed that gene expression of Caspase3 or Caspase7 was obviously elevated after stress treatment. Apaf1 was not altered at its gene expression level, and p53 was significantly decreased after various stress treatment. Caspase assay demonstrated that Caspase-3, -8, -9 enzyme activities in newt testis were significantly elevated after heat shock (40°C 2 h), cold exposure (4°C 12 h), and cadmium exposure (Cd 36 h), while Caspase3 and Caspase8 activities were increased with Caspase9 significantly decreased after starvation treatment.
  
  
  CONCLUSIONS
  Severe germ cell apoptosis triggered by heat shock, cold exposure, and cadmium exposure was Caspase3 dependent, which probably involved both extrinsic and intrinsic pathways. Apaf1 may be involved in this process without elevating its gene expression. But starvation-induced germ cell apoptosis was likely mainly through extrinsic pathway. p53 was probably not responsible for stress-induced germ cell apoptosis in newt testis. The intriguing high occurrence of spermatid and sperm apoptosis probably resulted from the sperm morphology and unique reproduction policy of Chinese fire-belly newt, Cynops orientalis.
authors: The Sperm Laboratory, College of Life Sciences, Zhejiang University, Hangzhou, People's Republic of China.
authors: Da-Hui
authors: DH
authors: Wang
authors: Jian-Rao
authors: JR
authors: Hu
authors: Li-Ya
authors: LY
authors: Wang
authors: Yan-Jun
authors: YJ
authors: Hu
authors: Fu-Qing
authors: FQ
authors: Tan
authors: Hong
authors: H
authors: Zhou
authors: Jian-Zhong
authors: JZ
authors: Shao
authors: Wan-Xi
authors: WX
authors: Yang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D053477:Apoptotic Protease-Activating Factor 1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D002104:Cadmium / Q000633:toxicity; D053148:Caspase 3 / Q000235:genetics / Q000378:metabolism*; D053179:Caspase 7 / Q000235:genetics / Q000378:metabolism*; D002681:China; D018076:DNA, Complementary / Q000235:genetics; D005455:Fluorescent Antibody Technique; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D020287:In Situ Nick-End Labeling; D008297:Male; D008954:Models, Biological; D008958:Models, Molecular; D008969:Molecular Sequence Data; D012455:Salamandridae / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D013091:Spermatogenesis / Q000187:drug effects / Q000235:genetics; D013094:Spermatozoa / Q000166:cytology / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D013312:Stress, Physiological; D013737:Testis / Q000187:drug effects / Q000201:enzymology; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*
chemical_list: D053477:Apoptotic Protease-Activating Factor 1; D018076:DNA, Complementary; D016159:Tumor Suppressor Protein p53; D002104:Cadmium; D053148:Caspase 3; D053179:Caspase 7