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The dramatic changes in the structure and function of sperm chromatin that occur during spermatogenesis have continued to intrigue researchers for more than a century. In addition to wanting to understand how these changes in chromatin organization affect genome function, many of the studies conducted in placental mammals have been driven by a desire to understand the relationship between sperm chromatin...
The purpose of this chapter is to provide a comprehensive overview of spermatogenesis and the various steps involved in the development of the male gamete, including cellular processes and nuclear transformations that occur during spermatogenesis, to provide a clear understanding of one of the most complex cellular metamorphosis that occurs in the human body. Spermatogenesis is a highly complex temporal...
Protamines are the most abundant nuclear proteins packaging the mammalian male genome in the sperm nucleus. The main proposed functions of these proteins are condensation and streamlining of the sperm cell, protection of the genetic message, and contribution to the epigenetic organisation of the paternal genome. Different studies have demonstrated the presence of an altered expression of protamines...
At least two aspects of sperm chromatin seem to be vulnerable to DNA damage. The first is inherent within the structure of the chromatin, which predicts that the histone-bound segments are more susceptible to any type of DNA damaging agent than the protamine-bound DNA. The data support the conclusion that protamines do protect DNA from exogenous insults. The second aspect is the enzymes that are present...
Similar to interphase chromosomes, mammalian supercompact and genetically inactive sperm chromatin is arranged in non-overlapping chromosome territories. Recent works demonstrate that chromosome territories in sperm have defined and nonrandom intranuclear positioning. It is hypothesized that preferred localization of chromosomes in sperm together with well-organized chromosome architecture provide...
Human mitochondrial DNA (mtDNA) is 16.6 kb in size and resides in the mitochondrion. It encodes 13 of the subunits of the electron transfer chain that generates the vast majority of cellular ATP through the process of oxidative phosphorylation (OXPHOS). The importance of OXPHOS to sperm motility and function has been controversial. However, we present a case for the importance of OXPHOS in sperm function...
The development of male germ cells from the primordial germ cell stage to that of the mature spermatozoon is a key time of epigenetic reprogramming. Orchestrated by specialized enzymes, DNA methylation and histone modifications undergo dynamic changes throughout gametogenesis. Alterations to any level of the sperm epigenetic coding may affect fertility and the sperm’s contribution to normal embryo...
Spermatogenesis is a key process in mammalian reproduction. This highly ordered process requires precise and well-controlled programs governed by dynamic patterns of gene expression. Some genes are exclusive to spermatogenic cells, while others are closely related to genes expressed in somatic cells. Although key genes in male germ cell development have been identified, the biological mechanisms and...
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