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Role of importins in reproduction
Mertová, Irem ; Frolíková, Michaela (advisor) ; Bubeníčková, Filipa (referee)
Importins are proteins from a group of karyopherins, which provide transport of proteins into the nucleus both in somatic cells and gametes. Transport of specific transcription factors plays an important role in gametes and affects key events of reproduction. In mammals, reproduction is mediated by the process of sexual reproduction. In this event, a haploid gamete is formed in each parent, which in later stages of fertilization combine and make a diploid zygote. Gene expression in gametes differs dramatically from somatic cells. In gametes, translation is suspended and specific proteins are expressed only at certain stages of cell development. Proteins determined for transport into the nucleus contain various nuclear localization signals, which are detected by different types of importins. Based on studying differences in expression of individual types of importins in various phases of gametogenesis, we can deduce their roles in these processes. Role of importins was proven in gametogenesis, differentiation of stem cells and maturation of germ cells. On top of that, importins appear to play a role in defense of male germ cells against oxidative stress.
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Apoptotic changes in frozen-thawed ejaculate in stallions.
Bubeníčková, Filipa ; Šichtař, Jiří (advisor) ; Jindřich, Jindřich (referee)
The aim of the study was to evaluate the effect of incubation time, types of packaging , extenders and stallion´s individuality for the presence of apoptotic sperms after thawing insemination doses (ID).
The semen was collected from six Old Kladrubian stallions by standard collection method. Collected ejaculates were diluted with two extender types (GENT and LAKT) and filled into 0.5 ml straws and 5 ml aluminum tubes in which were frozen and stored in liquid nitrogen. The ID were evaluated for the presence of apoptotic sperm immediately after thawing (37 °C, 30 - 60 sec.) and after incubation 15, 30, 45 and 60 minutes after thawing using fluorochromes Yo-Pro 1, propidium iodide and fluorescence microscopy.
There was a statistically significant difference in the presence of apoptotic sperms in the ID diluted with different types of extender. In the ID frozen in Gent was higher number of apoptotic and apoptotic sperms from the total number of live cells. This results suggest a better survival rate of sperm in the extender Gent compared with lactate extender. It was shown the effect of packaging types for the presence of apoptotic sperms in the ID after thawing. Immediately after thawing there was statistically significantly higher average proportion of apoptotic spermatozoa in 5 ml tubes than in 0.5 ml straws. With incubation time the tests did not demonstrate any significant differences between different types of packaging. However, the percentage of apoptotic sperm cells from the total number of viable cells was higher in 0.5 ml straws. Nevertheless this difference was observed as statistically significant only after 1 hour incubation. When we compared the combination of the extender and the packaging type there were evident relevant differences. The common use of Gent and 5 ml tubes seems to give the best outcome.
The stallion´s individuality had significant effect on the presence of apoptotic sperms in cryopreserved ID. To increase the quality of produced ID it must be treated individually to each stallion, especially in case of the Old Kladrubian horse breed. High level of inbreeding can significantly affect semen quality and the success of reproduction.
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