Lectin spatial immunolocalization during in vitro capacitation in Tursiops truncatus spermatozoa

Abstract

Spermatozoa interactions with the female reproductive tract and oocyte are regulated by surface molecules such as glycocalyx. The capacitation process comprises molecular and structural modifications which increase zona pellucida binding affinity. Lectins allowed us to describe glycocalyx changes during maturation, capacitation and acrosome reaction. This study had as its aim to identify lectin binding patterns using four lectins with different carbohydrate affinity in bottlenose dolphin (Tursiops truncatus) spermatozoa both before and after in vitro capacitation. Two semen samples from the same dolphin obtained on consecutive days were used, with four different lectin binding patterns becoming visible in both samples before and after capacitation. A highly stained equatorial segment with prolongations at the edges appeared as the most frequent pattern with Wheat germ agglutinin (WGA) in uncapacitated spermatozoa. However, it was homogeneously distributed over the acrosomal region after capacitation. Instead, the use of Peanut agglutinin (PNA) resulted in most spermatozoa showing high labelling in the acrosomal periphery region before capacitation and a homogeneous staining in the acrosomal region within the population of capacitated spermatozoa. Nevertheless, the most representative patterns with Concavalin A (ConA) and Aleuria aurantia agglutinin (AAA) lectins did not change before and after capacitation, labelling the acrosomal region periphery. These findings could contribute to the understanding of the reproductive biology of cetaceans and the improvement of sperm selection techniques.

Characterization of Bottlenose Dolphin (Tursiops truncatus) Sperm Based on Morphometric Traits

“…Such subpopulations have been related with sensitivity to cryopreservation, leading in cases to a reduction in sperm head size [ 41 , 50 ] or even correlated with fragmented DNA [ 64 ]. Nevertheless, dolphin sperm subpopulations have only been described in connection with lectin patterns [ 65 ] and kinetic variables [ 16 ]. In the present study, the types of sperm produced by both males had different traits, as observed by the clusterization of the sperm population, suggesting that a given male may produce a mix of different sperm with different functions.…”

Quantification and Topographical Distribution of Terminal and Linked Fucose Residues in Human Spermatozoa by Using Field Emission Scanning Electron Microscopy (FE-SEM)

“…To date, the most convenient method for detecting glycoconjugate moieties has been the lectin assay [ 3 , 4 ]. This methodology revealed distinct changes in glycosylated sperm constituents during the capacitation process in mammals [ 5 , 6 , 7 , 8 , 9 ]. Thereby, the removal of sialic acid [ 10 ] or the remarkable mannose or N-acetylgalactosamine redistribution through different membrane domains has been reported during in vitro capacitation [ 5 , 9 ], elucidating the potential role of these conjugates.…”