ABSTRACT
It is necessary to obtain basic information on transcription factors expressed in the spermatids of livestock to determine mechanisms of defective spermiogenesis. In this study, we characterized the activator cAMP responsive element modulator (CREM) ortholog isoforms in porcine testicular germ cells and ejaculated sperm. At least two kinds of porcine activator CREM τ family ortholog mRNAs were more strongly expressed in the testis than in kidney or liver. The activator CREM isoform ortholog proteins were localized in nuclei of round spermatids and around nuclei of elongated spermatids. Furthermore, approximately 34% of ejaculated sperm had the activator CREM isoform ortholog proteins at their connecting piece. This is apparently the first report demonstrating the expression and localization of the activator CREM isoform ortholog proteins in spermatids and ejaculated sperm of a livestock species.
Subject(s)
Cyclic AMP Response Element Modulator/metabolism , Spermatids/metabolism , Swine/metabolism , Amino Acid Sequence , Animals , Cyclic AMP Response Element Modulator/analysis , Cyclic AMP Response Element Modulator/chemistry , Male , Molecular Sequence Data , Protein Isoforms/analysis , Protein Isoforms/chemistry , Protein Isoforms/metabolism , RNA, Messenger/metabolism , Sequence Alignment , Spermatozoa/metabolism , Testis/metabolismABSTRACT
This study is a detailed investigation of changes in epididymal protein anti-agglutinin on ejaculated boar spermatozoa during an incubation designed to promote capacitation in vitro. Ejaculated spermatozoa were collected from six mature boars, washed, and incubated to promote capacitation. Sperm samples were subjected to Western blotting-densitometric analyses, flow cytometry after immunostaining and immunocytochemical observation by indirect immunofluorescence. An antiserum to anti-agglutinin was raised in a rabbit by subcutaneous injection of a purified antigen, as described previously (Harayama et al. 1999). Western blotting-densitometric analyses revealed an approximate halving of the amount of sperm-bound anti-agglutinin during the first 45-min incubation, followed by a gradual decrease thereafter. Comparison between immunostained sperm samples by flow cytometry before and after incubation confirmed this decrease in sperm-bound anti-agglutinin during the incubation. Microscopic characterization established that this decrease occurred mainly on the acrosome. Supplementation with seminal plasma (5% or 10%, v/v) attenuated the decrease. These findings are consistent with the conclusion that a large portion of the anti-agglutinin bound to sperm acrosomes is released at an early stage of the capacitation process in vitro.
Subject(s)
Epididymis/metabolism , Sialoglycoproteins/metabolism , Sperm Agglutination/immunology , Sperm Capacitation/physiology , Acrosome Reaction , Animals , Blotting, Western , Densitometry , Ejaculation , Flow Cytometry , In Vitro Techniques , Male , Rabbits , Sialoglycoproteins/immunology , SwineABSTRACT
The present study was conducted to reveal the effects of calcium and bicarbonate on the occurrence of head-to-head agglutination in ejaculated boar spermatozoa in vitro. Boar spermatozoa were washed and incubated in a modified Krebs-Ringer bicarbonate (mKRB) in a 37 degrees C CO2 incubator (5% CO2 in air) for 1-5 h. Before and after the incubation, aliquots of each sperm sample were fixed, smeared on glass slides, and stained with a phosphate-buffered solution of Giemsa to assess the percentages of head-to-head agglutinated spermatozoa. Before the incubation, only 5-12% of the spermatozoa were agglutinated. After the 1-h incubation, however, the percentage of head-to-head agglutinated spermatozoa rose to approximately 50%, followed by only minor increases thereafter. This rise was dependent on the concentrations of calcium chloride contained in the mKRB and was attenuated by the addition of 2 mM [ethylenebis(oxyethylenenitrilo)]tetra-acetic acid (EGTA) to the medium. Moreover, the replacement of sodium bicarbonate with 2-[4-(2-hydroxyethyl)-1-piperazinyl]ethanesulfonic acid (Hepes) in the medium and treatment with ruthenium red, which have both been shown previously to inhibit calcium uptake by boar spermatozoa, significantly reduced the rise. Based on these findings, it was concluded that extracellular calcium and bicarbonate are key factors regulating head-to-head agglutination in boar spermatozoa. The possible relationship between agglutinability and the fertilizing ability of boar spermatozoa is also discussed.
