Related Experiment Videos
Human sperm tail fibrous sheath undergoes phosphorylation during its development
A Jassim1, D J Gillott, Y al-Zuhdi
1Department of Immunology, London Hospital Medical College, UK.
Abstract:
The phosphorylation of the human sperm tail fibrous sheath as a maturational step during its development is reported for the first time. This was demonstrated using GDA-J/F3 and RT97 monoclonal antibodies (MoAb) which recognize the fibrous sheath. In indirect immunofluorescence microscopy of frozen sections of human adult testes, the two antibodies reacted with the assembled fibrous sheath only, but the numbers of sperm tails stained with RT97 were consistently lower than those treated with GDA-J/F3. Furthermore, by using double indirect immunofluorescence, although the majority of spermatozoa were doubly stained with the two MoAbs, some GDA-J/F3-positive sperm tails were negative with RT97. In epididymal and ejaculated spermatozoa, the two antibodies stained all the tails. This indicated that the ontogenic appearance of the GDA-J/F3 epitope precedes that of RT97. In Western blotting and/or indirect immunofluorescence of spermatozoa, treatment of samples with alkaline phosphatase abolished the reactivity of RT97 while that of GDA-J/F3 MoAb was not affected. This finding indicated that the RT97 but not the GDA-J/F3 epitope was phosphorylated. Together, these results therefore reveal that during tail morphogenesis, the fibrous sheath undergoes phosphorylation as part of its structural maturation. Screening of sperm cell precursors recovered from oligozoospermic donors showed reaction of some abnormal germ cells with GDA-J/F3 MoAb but not with RT97, suggesting the possible failure of phosphorylation of the fibrous sheath protein in these cells. The significance of these findings is discussed together with the biological importance of phosphorylation to the fibrous sheath.
Insights
Human sperm fibrous sheath phosphorylation is a key maturational step. Monoclonal antibodies revealed that the RT97 epitope appears later and is phosphorylated, unlike the GDA-J/F3 epitope.
Area of Science:
- Reproductive Biology
- Spermatozoa Development
- Cellular Phosphorylation
Background:
- The fibrous sheath is a crucial structure in the human sperm tail, essential for motility.
- Understanding the maturation process of the fibrous sheath is vital for male fertility research.
- Specific molecular events during sperm development remain incompletely understood.
Purpose of the Study:
- To investigate the role of phosphorylation in the structural maturation of the human sperm tail fibrous sheath.
- To determine the temporal appearance and molecular characteristics of fibrous sheath epitopes during sperm development.
Main Methods:
- Utilized indirect immunofluorescence microscopy with GDA-J/F3 and RT97 monoclonal antibodies (MoAb) on human testicular sections and spermatozoa.
- Employed Western blotting and alkaline phosphatase treatment to assess epitope phosphorylation.
- Analyzed sperm cell precursors from oligozoospermic donors.
Main Results:
- The GDA-J/F3 epitope appears earlier in fibrous sheath development than the RT97 epitope.
- Alkaline phosphatase treatment abolished RT97 antibody reactivity, indicating RT97 epitope phosphorylation.
- GDA-J/F3 reactivity remained unaffected by alkaline phosphatase, suggesting it is not phosphorylated.
- Abnormal germ cells in oligozoospermic donors showed GDA-J/F3 reactivity but lacked RT97 reactivity, suggesting failed phosphorylation.
Conclusions:
- Phosphorylation of the fibrous sheath is a significant maturational event during human sperm tail morphogenesis.
- The findings reveal distinct molecular maturation pathways for different fibrous sheath epitopes.
- Failure of fibrous sheath phosphorylation may be implicated in certain forms of male infertility.