Adhesion between plasma membrane and mitochondria with linking filaments in relation to migration of cytoplasmic droplet during epididymal maturation in guinea pig spermatozoa

2010 ◽  
Vol 341 (3) ◽  
pp. 429-440 ◽  
Author(s):  
Fumie Suzuki-Toyota ◽  
Chizuru Ito ◽  
Mamiko Maekawa ◽  
Yoshiro Toyama ◽  
Kiyotaka Toshimori
Author(s):  
N. Seki ◽  
Y. Toyama ◽  
T. Nagano

It is believed that i ntramembra.nous sterols play an essential role in membrane stability and permeability. To investigate the distribution changes of sterols in sperm membrane during epididymal maturation and capacitation, filipin has been used as a cytochemical probe for the detection for membrane sterols. Using this technique in combination with freeze fracturing, we examined the boar spermatozoa under various physiological conditions.The spermatozoa were collected from: 1) caput, corpus and cauda epididymides, 2) sperm rich fraction of ejaculates, and 3)the uterus 2hr after natural coition. They were fixed with 2.5% glutaraldehyde in 0.05M cacodylate buffer (pH 7.4), and treated with the filipin solution (final concentration : 0.02.0.05%) for 24hr at 4°C with constant agitation. After the filipin treatment, replicas were made by conventional freeze-fracture technique. The density of filipin-sterol complexes (FSCs) was determined in the E face of the plasma membrane of head regions.


1973 ◽  
Vol 21 (5) ◽  
pp. 488-498 ◽  
Author(s):  
R. E. POELMANN ◽  
W. T. DAEMS ◽  
E. J. VAN LOHUIZEN

This cytochemical and electron microscopic study on peritoneal macrophages of the guinea pig has raised doubts concerning the validity of lead methods for the demonstration of plasma membrane-bound adenosine triphosphatase activity. The problems encountered are inherent in the use of lead ions as a capture reagent. The nonenzymatically formed precipitates reflect sites of heterogeneous nucleation specific for certain kinds of cells, e.g., resident peritoneal macrophages, eosinophilic granulocytes and, to a lesser degree, exudate monocytes. This type of precipitation is also catalyzed on the surface of nonbiologic matrices such as latex particles. Enzymatic processes may well occur, but they cannot be distinguished from nonenzymatic processes.


1998 ◽  
Vol 292 (2) ◽  
pp. 427-433 ◽  
Author(s):  
K. Yoshinaga ◽  
I. Tanii ◽  
D. K. Saxena ◽  
K. Toshimori

1991 ◽  
Vol 1061 (2) ◽  
pp. 185-196 ◽  
Author(s):  
Ajay P.S. Rana ◽  
Gopal C. Majumder ◽  
Suniti Misra ◽  
Amitabha Ghosh

Development ◽  
1983 ◽  
Vol 75 (1) ◽  
pp. 259-270
Author(s):  
Stephen J. Gaunt

The rat sperm surface antigen 2D6, located over the entire surface of the spermatozoon, is shown by use of a monoclonal antibody in indirect immunofluorescence experiments to spread laterally over the surface of the egg after fusion of sperm and egg plasma membranes at fertilization. Freshly fertilized eggs, obtained from superovulated rats 14h after hCG injection, showed the 2D6 antigen to have spread in a gradient over a discrete fan-shaped area of the egg surface anterior to the protruding sperm tail. Eggs at a later stage of sperm incorporation, obtained 20 h after hCG injection, snowed that the spread of antigen had extended to cover most or all of their surfaces. By 40 h after hCG injection, the approximate time that fertilized eggs cleaved to form 2-cell embryos, most of the 2D6 antigen had been lost from the cell surface. Fertilized eggs, but not unfertilized eggs or 2-cell embryos, were lysed by 2D6 monoclonal antibody in the presence of guinea pig complement. A model for sperm-egg fusion is presented to account for the observed pattern of spreading shown by the 2D6 antigen. The possible role of sperm antigens on the egg surface is discussed.


Reproduction ◽  
2010 ◽  
Vol 140 (5) ◽  
pp. 673-684 ◽  
Author(s):  
Yadira Bastián ◽  
Ana L Roa-Espitia ◽  
Adela Mújica ◽  
Enrique O Hernández-González

Research on fertilization in mammalian species has revealed that Ca2+is an important player in biochemical and physiological events enabling the sperm to penetrate the oocyte. Ca2+is a signal transducer that particularly mediates capacitation and acrosome reaction (AR). Before becoming fertilization competent, sperm must experience several molecular, biochemical, and physiological changes where Ca2+plays a pivotal role. Calpain-1 and calpain-2 are Ca2+-dependent proteases widely studied in mammalian sperm; they have been involved in capacitation and AR but little is known about their mechanism. In this work, we establish the association of calpastatin with calpain-1 and the changes undergone by this complex during capacitation in guinea pig sperm. We found that calpain-1 is relocated and translocated from cytoplasm to plasma membrane (PM) during capacitation, where it could cleave spectrin, one of the proteins of the PM-associated cytoskeleton, and facilitates AR. The aforementioned results were dependent on the calpastatin phosphorylation and the presence of extracellular Ca2+. Our findings underline the contribution of the sperm cytoskeleton in the regulation of both capacitation and AR. In addition, our findings also reveal one of the mechanisms by which calpain and calcium exert its function in sperm.


2008 ◽  
Vol 78 (Suppl_1) ◽  
pp. 76-76
Author(s):  
Fumie Suzuki-Toyota ◽  
Chizuru Ito ◽  
Mamiko Maekawa ◽  
Yoshiro Toyama ◽  
Kiyotaka Toshimori

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