title: A mitochondrial mechanism is involved in apoptosis of Robertsonian mouse male germ cells.
abstract: The aim of this study was to determine whether the intrinsic mechanism of apoptosis is involved in the death of germ cells in Robertsonian (Rb) heterozygous adult male mice. Testes from 5-month-old Rb heterozygous CD1 x Milano II mice were obtained and compared with those from homozygous CD1 (2n=40) and Milano II (2n=24) mice. For histological evaluation of apoptosis, TUNEL labelling and immunohistochemistry were used to localise Bax and cytochrome c. Expression of calbindin D(28k) (CB), an anti-apoptotic molecule, was also analysed by immunohistochemistry and immunoblotting. Testicular ultrastructure was visualised by electron microscopy. Morphology and cell associations were abnormal in the Rb heterozygous seminiferous epithelium. An intense apoptotic process was observed in tubules at stage XII, mainly in metaphase spermatocytes. Metaphase spermatocytes also showed Bax and cytochrome c redistributions. Mitochondria relocated close to the paranuclear region of spermatocytes. CB was mainly expressed in metaphase spermatocytes, but also in pachytene spermatocytes, spermatids and Sertoli cells at stage XII. The co-localisation of CB and TUNEL labelling was very limited. Sixty per cent of metaphase spermatocytes were apoptotic and calbindin negative, while 40% were calbindin positive without signs of apoptosis. Ten per cent of the Bax- and cytochrome c-positive cells were also calbindin positive. These data suggest that apoptosis of the germ cells in heterozygous mice occurs, at least in part, through a mitochondrial-dependent mechanism. Calbindin overexpression might prevent or reduce the apoptosis of germ cells caused by Rb heterozygosity, which could partially explain the subfertility of these mice.
authors.affiliation: Dipartimento di Biologia Animale, Università degli Studi di Pavia, Piazza Botta, 9-10, I-27100 Pavia, Italy.
authors.forename: Valeria
authors.initials: V
authors.lastname: Merico
authors.forename: Gabriela Diaz
authors.initials: GD
authors.lastname: de Barboza
authors.forename: Chiara
authors.initials: C
authors.lastname: Vasco
authors.forename: Ruben
authors.initials: R
authors.lastname: Ponce
authors.forename: Valeria
authors.initials: V
authors.lastname: Rodriguez
authors.forename: Silvia
authors.initials: S
authors.lastname: Garagna
authors.forename: Nori
authors.initials: N
authors.lastname: Tolosa de Talamoni
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology; D015415:Biomarkers / Q000032:analysis; D064026:Calbindins; D045304:Cytochromes c / Q000032:analysis; D006579:Heterozygote; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D007248:Infertility, Male / Q000473:pathology*; D008297:Male; D008677:Metaphase; D051379:Mice; D008817:Mice, Mutant Strains; D046529:Microscopy, Electron, Transmission; D008928:Mitochondria / Q000502:physiology*; D023421:Models, Animal; D064030:S100 Calcium Binding Protein G / Q000032:analysis; D012671:Seminiferous Tubules / Q000648:ultrastructure; D012708:Sertoli Cells / Q000737:chemistry; D013087:Spermatids / Q000737:chemistry / Q000648:ultrastructure; D013090:Spermatocytes / Q000737:chemistry / Q000648:ultrastructure; D013094:Spermatozoa / Q000648:ultrastructure*; D013737:Testis / Q000648:ultrastructure; D051028:bcl-2-Associated X Protein / Q000032:analysis
chemical_list: D015415:Biomarkers; D064026:Calbindins; D064030:S100 Calcium Binding Protein G; D051028:bcl-2-Associated X Protein; D045304:Cytochromes c