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The mechanism of impaired formation of head-tail coupling apparatus in centrobin deficient acephalic spermatozoa
Vlčková, Monika ; Frolíková, Michaela (advisor) ; Krejčová, Tereza (referee)
Acephalic sperm syndrome (ASS) is a rare form of teratozoospermia that is probably genetic in origin. The sperm of individuals with this syndrome have a damaged apparatus connecting the head and flagellum (HTCA), which leads to the formation of acephalic sperm, i.e. sperm with separate heads from flagella. Individuals affected by ASS are almost exclusively infertile. One of the proteins whose mutation causes ASS is SUN5. Together with KASH proteins, SUN proteins are part of the so-called LINC complex, which ensures the connection of the nucleoskeleton with the cytoskeleton. Centrobin is a protein involved in centriole duplication and assembly of the dividing spindle. Rats carrying a defective gene for centrobin have reduced fertility and exhibit an ASS phenotype. For that reason, this model organism was used in this work to study the possible interrelationships of proteins involved in the formation of ASS. Given the similar phenotype of centrobin and SUN5 mutated spermatozoa, there is a possibility that centrobin interacts with one of the LINC complex proteins and together they participate in the formation of the head-flagella junction. Sperm from rats with a defective centrobin gene also show significant damage to the flagella. Decreased Odf1 protein expression has previously been reported in ASS...
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Sperm centrioles and their role in reproduction
Vlčková, Monika ; Frolíková, Michaela (advisor) ; Liška, František (referee)
Centrioles are evolutionarily conserved protein structures composed of microtubules. In somatic cells, centrioles serve as the basal body of cilia and flagella and allow the assembly of pericentriolar material, thereby creating the centrosome. Without centrosome, animal cells are not capable of nuclear division. Centrioles do not arise de novo and their formation always requires the presence of a preexisting centriole. Since there are no centrioles in the egg at the time of fertilization, unlike spermatozoa, sperm is the carrier of centrioles and therefore all of the centrioles of the emerging organism are of paternal origin. There are two centrioles in the sperm - a cylindrical shape proximal and a distal one, which is perpendicular to the proximal. The sperm centrioles are the basis for the formation of the sperm flagellum and after fertilization form the mitotic spindle of the zygote, necessary for equal DNA and cell distribution. It follows from the above that the presence of centrioles in sperm is essential in mammals and defects in their structure may lead to male sterility or embryo development disorders. However, sperm centrioles differ from somatic centrioles in their structure and behavior and understanding these differences is one of the important tasks of reproductive biology.
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