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The Drosophila HP1 gene contains a highly conserved sequence, the chromobox, which can be used to isolate HP1-like genes from both mouse (M31 and M32) and man (HSM1) (Singh et al., 1991). Here we report that a monoclonal antibody (MoAb) raised against the M31 protein recognises a 26-kDa protein in murine and human nuclear extracts and localises to large(More)
A reduction in plasma membrane cholesterol is one of the early events that either triggers or is closely associated with capacitation of mammalian spermatozoa. In this investigation, we have examined the effects of cholesterol efflux on tyrosine phosphorylation, lipid diffusion, and raft organization in boar spermatozoa. Results show that a low level of(More)
Compartmentalization of surface membrane antigens into discrete regions or domains is a characteristic feature of differentiated cells. In mammalian spermatozoa at least 5 surface domains are known, implying the presence of barriers or boundaries within the plasma membrane. Using the technique of fluorescence recovery after photobleaching (FRAP) to measure(More)
Spermatozoa are highly polarised cells with a compartmentalised distribution of lipids and proteins in their plasma membrane. It is not known how these compartments are stably maintained in what is essentially a fluid environment. In this investigation we have examined the hypothesis that intramembranous diffusion barriers selectively retain some components(More)
M cells present in Peyer's patch tissue transport enteric antigens for presentation to underlying lymphoid tissue to initiate immune responses against intestinal infection. Present work investigates how interactions taking place between bacteria, epithelial cells, and immunocytes could contribute to initial detection and later elimination of enteric(More)
The interaction between polystyrene microspheres and the follicle-associated epithelium of rabbit Peyer's patches has been examined. Microspheres bind selectively to, and are transcytosed by, membranous or microfold (M) cells within the follicle-associated epithelium. M cells are able to transport, in 45 min, approximately 105 microspheres of 0.46 μm(More)
1. Using a new method of quantitative cytochemistry to determine alkaline phosphatase activity, it was possible to identify M cells and distinguish two further types of enterocytes present in mouse Peyer's patch follicle-associated epithelial tissue. 2. A quantitative description of these three cell types was provided by making direct absorbance(More)
1. Pig intestinal sucrase and maltase activities increase markedly, and lactase activity decreases, during the second week of post-natal life. Correlations noted between the time course describing these changes and that found previously to describe a decline in the ability of the pig intestine to take up macromolecules suggest that both events are subject(More)
The plasma membrane of mammalian spermatozoa shows pronounced lateral asymmetry with many glycoproteins restricted to specific domains. Some of these antigens are freely diffusing throughout the membrane whereas others appear static in position. It is not clear whether these concepts also apply to membrane lipids. In this investigation we have used(More)
The molecules on mammalian spermatozoa that mediate recognition and binding to the zona pellucida of the egg are still not understood. Current concepts favour their assembly into multimolecular complexes in the plasma membrane in response to cholesterol efflux, an important step during sperm capacitation. Here, we track in real time diffusion of(More)