Seminal quality and global proteomic analysis of spermatozoa from captive Amazon squirrel monkeys (Saimiri collinsiOsgood, 1916) during the dry and rainy seasons

Abstract

24The squirrel monkey (Saimiri collinsi), a Neotropical primate endemic to the Amazon in Brazil, is 25 used as a biological model for reproductive research on the genus Saimiri. Although this animal is 26 known to exhibit reproductive seasonality, nothing is known about the differences in its seminal 27 quality, sperm protein composition, or sperm protein profile between the breeding (dry) and non-28 breeding (rainy) seasons. Thus, the aims of this study were to evaluate the quality of S. collinsi 29 semen during the dry and rainy seasons and to describe the global sperm proteomics and expression 30 variations in the sperm proteins during the two seasons. Aside from the pH, there was no difference 31 in the seminal quality between the dry and rainy seasons. The study approach based on bottom-up 32 proteomics allowed the identification of 2343 proteins present in the sperm samples throughout 33 these two seasons. Of the 79 proteins that were differentially expressed between the two seasons, 39 34 proteins that were related to spermatogenesis, sperm motility, capacitation, fecundation, and defense 35 systems against oxidative stress were upregulated in the dry season. Knowledge on the sperm 36 proteins provides crucial information for elucidating the underlying mechanisms associated with 37 sperm functionality. Thus, our results help to advance our understanding of the reproductive 38 physiology of S. collinsi, providing valuable information for the improvement of protocols used in 39 assisted reproduction techniques for the conservation of endangered Saimiri species. 40 41 42 3 43 4 64Mammalian male fertility depends on physiological events that begin with spermatogenesis 65 and culminate with successful adhesion/signaling between the sperm membrane and the 66 extracellular coat of the oocyte, followed by adhesion/fusion between the oocyte and sperm 67 membranes during fertilization in the female reproductive tract [16, 17]. Proteins expressed by 68 spermatozoa and those from the seminal plasma that bind to the sperm plasma membrane render the 69 spermatozoa capable of fertilizing a mature oocyte [18, 19]. Studies in animals and humans have 70 described sperm proteins that have significant associations with sperm motility (i.e., L-lactate 71 dehydrogenase and dynein heavy chain 1 (DNAH1)) [20, 21], sperm capacitation (i.e., clusterin, 72 spermadhesin, and mitochondrial peroxiredoxin-5) [22, 23], and fertility (i.e., enolase 1, ropporin-73 1-like protein (ROPN1), and Izumo sperm-egg fusion 1 (IZUMO1)) [24, 25]. 74In non-human primates, sperm proteomics has been carried out only in Old World primates 75 for characterization of the sperm protein profile [18,[26][27][28][29]. Although these studies have been 76 carried out in the genus Macaca, which also exhibits reproductive seasonality [30], nothing is 77 known about the changes that may occur in the sperm protein profile during the non-breeding and 78 breeding seasons, and the influence of these changes on the seminal quality of these animals. 79Knowledge about ...