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PubMed1993

Tracing the incorporation of the sperm tail in the mouse zygote and early embryo using an anti-testicular alpha-tubulin antibody.

The mechanism of sperm tail incorporation and the fate of the tail during mouse fertilization and early embryogenesis were examined. Time-lapse video microscopy and anti-tubulin immunofluorescence show that the incorporation of the sperm tail, but not the sperm head, is sensitive to cytochalasin B (a microfilament inhibitor). Colcemid, a microtubule inhibitor, does not affect tail incorporation. High-resolution, low-voltage scanning electron microscopy demonstrates that the plasma membrane covering the sperm tail does not appear to fuse with the oocyte membrane during in vitro fertilization in the presence of cytochalasin. In control and colcemid-treated oocytes, the plasma membrane along the sperm tail, which is oriented tangential to the egg surfaces, appears to fuse with the oocyte membrane at multiple sites. An antibody to testicular alpha-tubulin detects sperm-derived, but not egg, microtubules and this has permitted us to trace the behavior and disappearance of the sperm tail during embryogenesis. Conventional and confocal microscopy show that following sperm incorporation, the tail often splays into multiple fibers. At the two-cell stage, the axoneme may be localized in either blastomere or it may be found to run through the midbody between both blastomeres. The tail appears to shorten by the 8-cell stage and is undetectable after the 16-32 cell stage. In morulae, tail fragments have been found in outer cells but not in inner ones, and fragments have not be found in blastocysts. These data suggest that microtubules of sperm and oocytes contain different isotypes of alpha-tubulin, nongenomic sperm-derived components survive at least to the morula stage of mouse development, and egg microfilaments are involved in the incorporation of the sperm tail but not the sperm head, which demonstrates that motility during sperm incorporation is different in mammals when compared to lower vertebrates and invertebrates.

Actin Cytoskeleton↗

PubMed1978

Cilia and sperm tail abnormalities in Polynesian bronchiectatics.

Sperm tails and bronchial cilia from Polynesians with bronchiectasis were examined in the electron microscope. The outer doublet tubules of the axonemal skeleton in these organelles either lacked dynein arms or had only partial arms. Various other cilial abnormalities were common. The sperm were immotile and pulmonary mucociliary clearance was reduced or absent.

Bronchi↗

PubMed1995

Identification of heterotrimeric G proteins in human sperm tail membranes.

Heterotrimeric G proteins play important roles as signal transducing components in various mammalian sperm functions. We were interested in the distribution of G proteins in human sperm tails. Prior to membrane preparation, spermatozoa were separated from contaminating cells which are frequently present in human ejaculates. Enriched human sperm tail membranes were generated by using hypoosmotic swelling and homogenization procedures. Antisera against synthetic peptides were used to identify G proteins in immunoblots. AS 8, an antiserum directed against an amino acid sequence that is found in most G protein alpha-subunits, and A 86, which detects all known pertussis toxin-sensitive alpha-subunits, reacted specifically with a 40-kDa protein. Antisera against individual G protein alpha-subunits failed to detect any specific antigens in enriched tail membranes. AS 36, recognizing the beta 2-subunit of G proteins, identified a 35-kDa protein in sperm tail membranes. Antisera against the 36-kDa beta 1-subunit did not detect any relevant proteins in the membrane fraction. Neither G protein alpha-subunits nor G protein beta-subunits were found in the cytosol. ADP ribosylation of spermatozoal membrane or cytosolic proteins revealed no pertussis toxin-sensitive alpha-subunits. However, membrane preparations of nonpurified human spermatozoa contained alpha i2 subunits, as shown immunologically and by ADP ribosylation; they most probably derived from somatic cells which are frequently present in human ejaculates. Our results stress the fact that spermatozoa need to be purified before sperm membrane preparation to avoid misinterpretations caused by contaminating cells. Furthermore, we suggest that G proteins in membranes of human sperm tails belong to a novel subtype of G protein alpha-subunits; the putative beta-subunit was identified as a beta 2-subunit.

Cell Membrane↗

PubMed2005

The mouse T complex gene Tsga2, encoding polypeptides located in the sperm tail and anterior acrosome, maps to a locus associated with sperm motility and sperm-egg interaction abnormalities.

Previous studies of sperm from mice heterozygous for a t haplotype (t) and heterospecific combinations of the t complex identified two tightly linked genetic factors responsible for t/t male sterility related to expression of the flagellar waveform aberration, curlicue. Dnahc8, an axonemal dynein heavy chain gene, is a strong candidate for the proximal factor, Ccua, but the identity of the distal factor, Ccub, is unknown. In the present study, we employ motility assays of sperm from males heterozygous for t and novel heterospecific combinations of the t complex to demonstrate that Ccub is a composite of at least two synergic elements, Ccub1, positioned within a genomic interval spanning approximately 0.6 Mb immediately distal to Dnahc8, and Ccub2, situated in a region approximately 4-7 Mb distal to Ccub1. We also show that Tsga2, a testis-restricted gene, fulfills many of the prerequisites required to make it a strong candidate for Ccub1. These include: 1) its location within the aforementioned genomic interval; 2) a highly reduced level of testis expression by its heterospecific allele relative to the level of expression of its t allele; 3) determination that TSGA2(t) carries numerous nonsynonymous mutations in residues otherwise highly conserved in all known orthologous proteins; 4) the detection of major TSGA2 polypeptides in sperm protein extracts; and 5) the apparent distribution of these polypeptides in major sperm tail structures. Surprisingly, these TSGA2 isoforms appear to localize in the vicinity of the anterior acrosome, as well, suggesting that Tsga2 may also play a role in sperm-egg interaction. Finally, our results indicate that a TSGA2 polypeptide with apparent similarities to the smaller of the two sperm isoforms is expressed by epididymal cells.

Acrosome↗

PubMed1992

Quantitative ultrastructural analysis of sperm tails reveals flagellar defects associated with persistent asthenozoospermia.

Sperm tail morphology was examined in 10 infertile asthenozoospermic men to determine whether poor sperm motility was caused by ultrastructural defects of the flagellum. In this quantitative analysis, the numbers of outer doublet and central pair microtubules, outer and inner dynein arms and radial spokes were counted in transverse sections of 75 axonemes from each patient and compared with similar data previously collected from 10 men with normal semen characteristics. Four patients had axonemal defects: two had severe microtubule abnormalities and two had more subtle but statistically significant deficiencies of dynein arms. These abnormalities would not have been detected by more commonly used qualitative examination. Three patients had no detectable ultrastructural abnormalities of the sperm tail, possibly indicating a metabolic deficiency. A further three patients had mid-piece abnormalities. Two had few, if any, flagellar mitochondria and the third patient had irregular and disorganized mitochondria. Quantitative ultrastructural analysis has revealed axonemal abnormalities in seven of 10 patients with previously unexplained asthenozoospermia.

Humans↗

PubMed1982

The evolution of the sperm tail.

In this paper the evolution of the sperm tail is discussed. The primitive motile apparatus is assumed to be a conventional '9 + 2' axoneme which persists in all aquatic phyla having external fertilisation. Where internal fertilisation has evolved in association with terrestrial life, the sperm tail has a '9 + 9 + 2' pattern: it has acquired new accessory proteins and has become enormously elongated. A subsequent trend is towards diminished motility, owing perhaps to the excessive development of skeletal structures and sophisticated copulatory organs. This is marked by unusual axoneme patterns and a lack of dynein arms. Aflagellate spermatozoa seem to represent a high evolutionary level. Finally, it appears that in the sperm of some groups motility has been regained. However, the axoneme never reappears: motility is produced instead by the spermatid manchette or an actin system.

Animals↗

PubMed2006

An intronic insertion in KPL2 results in aberrant splicing and causes the immotile short-tail sperm defect in the pig.

The immotile short-tail sperm defect is an autosomal recessive disease within the Finnish Yorkshire pig population. This disease specifically affects the axoneme structure of sperm flagella, whereas cilia in other tissues appear unaffected. Recently, the disease locus was mapped to a 3-cM region on porcine chromosome 16. To facilitate identification of candidate genes, we constructed a porcine-human comparative map, which anchored the disease locus to a region on human chromosome 5p13.2 containing eight annotated genes. Sequence analysis of a candidate gene KPL2 revealed the presence of an inserted retrotransposon within an intron. The insertion affects splicing of the KPL2 transcript in two ways; it either causes skipping of the upstream exon, or causes the inclusion of an intronic sequence as well as part of the insertion in the transcript. Both changes alter the reading frame leading to premature termination of translation. Further work revealed that the aberrantly spliced exon is expressed predominantly in testicular tissue, which explains the tissue-specificity of the immotile short-tail sperm defect. These findings show that the KPL2 gene is important for correct axoneme development and provide insight into abnormal sperm development and infertility disorders.

Alternative Splicing↗

PubMed1978

Selective incorporation of selenium-75 into a polypeptide of the rat sperm tail (1).

Selenium is necessary for normal sperm tail development in the rat. The biochemical locus of this requirement was investigated by intratesticular administration of (75Se)SeO3-2. Sperm were labeled primarily in tail keratin, a disulfide-stabilized fraction obtained by extracting isolated tails with sodium dodecyl sulfate (SDS). By incubation in 1% SDS-0.2 mM dithiothreitol, followed by sonication and centrifugation, the 75Se was separated from a residue rich in S and Zn, composed of dense fibers and connecting pieces. The extracted 75Se-labeled material was non-dialyzable, sensitive to pronase, retained most of its bound isotope following carboxymethylation, and displayed only one radioactive component, of 17,000 daltons, during SDS-polyacrylamide gel electrophoresis. It is suggested that the labeled moiety is a selenopolypeptide whose function is critical for normal assembly of the sperm tail.

Animals↗

PubMed1991

Human sperm tail fibrous sheath undergoes phosphorylation during its development.

The phosphorylation of the human sperm tail fibrous sheath as a maturational step during its development is reported for the first time. This was demonstrated using GDA-J/F3 and RT97 monoclonal antibodies (MoAb) which recognize the fibrous sheath. In indirect immunofluorescence microscopy of frozen sections of human adult testes, the two antibodies reacted with the assembled fibrous sheath only, but the numbers of sperm tails stained with RT97 were consistently lower than those treated with GDA-J/F3. Furthermore, by using double indirect immunofluorescence, although the majority of spermatozoa were doubly stained with the two MoAbs, some GDA-J/F3-positive sperm tails were negative with RT97. In epididymal and ejaculated spermatozoa, the two antibodies stained all the tails. This indicated that the ontogenic appearance of the GDA-J/F3 epitope precedes that of RT97. In Western blotting and/or indirect immunofluorescence of spermatozoa, treatment of samples with alkaline phosphatase abolished the reactivity of RT97 while that of GDA-J/F3 MoAb was not affected. This finding indicated that the RT97 but not the GDA-J/F3 epitope was phosphorylated. Together, these results therefore reveal that during tail morphogenesis, the fibrous sheath undergoes phosphorylation as part of its structural maturation. Screening of sperm cell precursors recovered from oligozoospermic donors showed reaction of some abnormal germ cells with GDA-J/F3 MoAb but not with RT97, suggesting the possible failure of phosphorylation of the fibrous sheath protein in these cells. The significance of these findings is discussed together with the biological importance of phosphorylation to the fibrous sheath.

Alkaline Phosphatase↗

PubMed2006

Cloning and characterization of a novel sperm tail protein, NYD-SP28.

In this study, a gene coding a novel human sperm tail protein named NYD-SP28 was cloned and characterized using a complementary DNA (cDNA) microarray. Its expression was 3.5 times higher in human testis than in fetal testis, and very high in human spermatozoa. The full length of NYD-SP28 cDNA was 1798 bp and encoded a 484-amino-acid protein. Motif analysis revealed that the protein contained a cluster of phosphorylation sites, N-glycosylation sites and N-myristoylation sites. Immunohistochemical analysis of normal human testes showed that NYD-SP28 was expressed in the cytoplasm of spermatogenic cells but not in interstitial cells. The EGFP-NYD-SP28 fusion protein was also localized in the cytoplasm of transfected 7721 cells. In human spermatozoa, NYD-SP28 immunoreactivity was detected in entire sperm tail. Using the two-dimensional (2-D) gel electrophoresis and immunoblotting technique, NYD-SP28 was found to be post-translationally modified during sperm capacitation. In conclusion, these results suggest that NYD-SP28 is a new human sperm tail protein and might play an important role during sperm capacitation.

Adult↗

PubMedDate not supplied

The best of all worlds or the best possible world? Developmental constraint in the evolution of beta-tubulin and the sperm tail axoneme.

Through evolutionary history, some features of the phenotype show little variation. Stabilizing selection could produce this result, but the possibility also exists that a feature is conserved because it is developmentally constrained--only one or a few developmental mechanisms can produce that feature. We present experimental data documenting developmental constraint in the assembly of the motile sperm tail axoneme. The 9+2 microtubule architecture of the eukaryotic axoneme has been deeply conserved. We argue that the quality of motility supported by axonemes with this morphology explains their long conservation, rather than a developmental necessity for the 9+2 architecture. However, our functional tests in Drosophila spermatogenesis reveal considerable constraint in the coevolution of testis-specific beta-tubulin and the sperm tail axoneme. The evolution of testis beta-tubulins used in insect sperm tail axonemes is highly punctuated, indicating some pressure acting on their evolution. We provide a mechanistic explanation for their punctuated evolution by testing structure-function relationships between testis beta-tubulin and the motile axoneme in D. melanogaster. We discovered that a highly conserved sequence feature of beta-tubulins used in motile axonemes is needed to specify central pair formation. Second, our data suggest that cooperativity in the function of internal beta-tubulin amino acids is needed to support the long axonemes characteristic of Drosophila sperm tails. Thus, central pair formation constrains the evolution of the axoneme motif, and intramolecular cooperativity makes the evolution of the internal residues path dependent, which slows their evolution. Our results explain why a highly specialized beta-tubulin is needed to construct the Drosophila sperm tail axoneme. We conclude that these constraints have fixed testis-specific beta-tubulin identity in Drosophila.

Animals↗

PubMed1999

Modulation of sperm tail protein tyrosine phosphorylation by pentoxifylline and its correlation with hyperactivated motility.

OBJECTIVE: To assess the effect of pentoxifylline on human sperm functions that are crucial to fertilization. DESIGN: Prospective, controlled study. SETTING: Academic tertiary care institute. PATIENT(S): Healthy male sperm donors. INTERVENTION(S): The effects of pentoxifylline (3.6 mM) on hyperactivated motility, sperm binding to the zona pellucida, and sperm protein tyrosine phosphorylation were evaluated. MAIN OUTCOME MEASURE(S): Hyperactivated motility was assessed by computer-assisted motion analysis, and tight binding of sperm to homologous zonae pellucidae was examined using the hemizona assay. Sperm protein phosphorylation was evaluated using indirect immunofluorescence with an antibody to phosphotyrosine (PY20). RESULT(S): Pentoxifylline significantly stimulated hyperactivated motility at 1 hour and 4 hours; it also significantly increased sperm binding to the zona pellucida and enhanced sperm tail tyrosine phosphorylation at 4 hours under capacitating conditions. There was a statistically significant correlation between hyperactivated motility and sperm tail protein phosphorylation. CONCLUSION(S): Pentoxifylline stimulates sperm functions that are essential to achieving fertilization under in vitro conditions in sperm obtained from fertile men. The enhancement of hyperactivated motility is associated with the stimulation of sperm tail tyrosine phosphorylation, suggesting a causal relation and the involvement of a modulatory effect after cyclic adenosine monophosphate-dependent phosphorylation of intermediate proteins.

Fertilization in Vitro↗

PubMed1996

Excision and disassembly of sperm tail microtubules during sea urchin fertilization: requirements for microtubule dynamics.

To determine the fate of the sperm tail during fertilization, the microtubules of the incorporated axoneme are measured using a monoclonal antibody against acetylated alpha-tubulin in zygotes from the sea urchin Strongylocentrotus purpuratus. This antibody recognizes axonemal microtubules, but does not recognize egg cytoplasmic tubulin or microtubules. The detachment of the axoneme from the male pronucleus occurs as early as 15 min post-insemination. Following excision, the axoneme is often found in close association with the female pronucleus during its migration to the male pronucleus. Fragmentation of the sperm tail, detected at 25 min, continues with only a few micrometers remaining at 85 min post-insemination. The fluorescence intensity of the axonemal fragments diminishes over time as compared to intact axonemes. At 100 min post-insemination, the sperm axoneme is no longer detected. Alternative imaging approaches using brief cold or elevated calcium extraction to disrupt the labile cytoplasmic, but not axonemal, microtubules, indicate that these observations are not due to changes in the post-translational modifications of alpha-tubulin. In the presence of nocodazole, a microtubule assembly inhibitor, a large portion of the tail remains visible at 100 min post-insemination; this suggests that microtubule dynamics are required for the disassembly of the sperm tail. Furthermore, the detachment of the axoneme from the male pronucleus requires the formation of the sperm aster. This suggests that the sperm aster microtubules both detach the axoneme from the male pronucleus, and also cause the translocation of the tail towards the female pronucleus after pronuclear union. In summary, the sperm tail is excised from the male pronucleus and the tail microtubules disassembled during the first cell cycle of sea urchin fertilization, and these events require new microtubule assembly within the zygote.

Animals↗

PubMed2003

Novel RING finger protein OIP1 binds to conserved amino acid repeats in sperm tail protein ODF1.

Outer dense fibers (ODFs) and the fibrous sheath (FS) are unique structures of the mammalian sperm tail. Recently, progress has been made in the molecular cloning of ODF and FS proteins, and because of this, questions addressing the morphogenesis and underlying protein network that make up sperm tail structures and their function can now be addressed. Using the N-terminal leucine zipper motif of the major ODF protein ODF1, we had previously isolated interacting proteins Odf2, Spag4, and Spag5. We report here a yeast two-hybrid strategy to isolate a novel rat testicular protein, OIP1, that binds to the evolutionarily conserved Cys-Gly-Pro repeats in the C-terminus of ODF1. OIP1 is expressed in round spermatids as well as in spermatocytes and several somatic tissues, albeit at a lower level. No expression was detectable in epididymis, heart, and smooth muscle. OIP1 protein localizes to the sperm tail in a pattern expected for an ODF1-interacting protein. OIP1 belongs to the family of RING finger proteins of the H2 subclass. Deletion of the putative RING motif significantly decreased binding to ODF1. Genomic analysis of rat Oip1 and Oip1 homologs indicates that Oip1 is highly conserved. Oip1 is subject to differential splicing and alternative polyadenylation events. It is interesting that Oip1 mRNAs have been reported that lack the exon encoding the putative RING finger.

Amino Acid Sequence↗

PubMed1988

Antigenic homology between rat sperm tail polypeptides and Sertoli cell secretory proteins.

A high performance liquid chromatographic procedure has been used for the purification of rat Sertoli cell secretory protein S70 and S45-S35 heterodimeric protein to determine their role during spermatogenesis. These two proteins display binding affinity for each other and appear antigenically related. We have observed that: 1. S70 and S45-S35 heterodimeric protein coelute during purification, 2. polyclonal antiserum raised against protein S70 recognizes common antigenic determinants in polypeptides S45 and S35, the disulfide-linked components of the heterodimeric protein, and 3. a monoclonal antibody that recognizes polypeptide S35 but does not crossreact with either protein S70 or polypeptide S45, immunoprecipitates the S70/S45-S35 heterodimeric protein complex. In immunofluorescent experiments, antisera raised against protein S70 and polypeptide components of S45-S35 heterodimeric protein immunoreact with two major sperm intracellular structures: the acrosome and periaxonemal outer dense fibers of sperm tail. Immunoreactivity was not detected on the sperm plasma membrane surface of unfixed, living sperm. Outer dense fibers extracted from sperm tails by a combined treatment with cetylthrimethylammonium bromide and 2-mercaptoethanol, yielded a characteristic polypeptide pattern. In immunoblotting experiments sperm tail polypeptides were recognized by polyclonal antisera raised against Sertoli cell secretory proteins. We conclude that Sertoli cell secretory proteins S70 and S45-S35 heterodimeric protein are antigenically related to each other and to keratin-like polypeptides from sperm tail.

Animals↗

PubMed1992

Isolation and biochemical characterization of the human sperm tail fibrous sheath.

The isolation and biochemical characterization of the human sperm tail fibrous sheath (FS) is described for the first time. Initially, the solubilization properties of the FS were assessed immunocytochemically using GDA-J/F3 and RT97 monoclonal antibodies (MoAbs) and morphologically by electron microscopy. Following extensive investigations to optimize the conditions for the FS isolation, a simple method was developed which involved sequential extraction of the flageller components with Triton-dithiothreitol (DTT) and urea-DTT. The procedure was monitored by phase contrast microscopy and the purity of the FS preparations was confirmed by electron microscopy. SDS-PAGE of the isolated FS revealed seven major protein bands with mol. wt of 97, 76, 62, 55, 33, 28 and 25 kDa. In Western blotting, the reaction of RT97 MoAb with supernatants from the various extraction steps and the isolated FS indicated that its target antigen (AJ-p97) was an integral FS product and that disulphide bonding was probably involved in its stabilization. The reactivity of normal and aprotruded sperm tails with GDA-J/F3 and RT97 MoAbs was not affected by Triton while the GDA-J/F3 staining of the cytoplasmic matrix of other abnormal spermatids was abolished, thus suggesting variation in the biochemical properties of GDA-J/F3 in normal and abnormal germ cells. These and other data indicate that the FS could be a modified form of intermediate filament.

Antibodies, Monoclonal↗

PubMed1994

AJ-FS9 monoclonal antibody detects masked antigens within the human sperm tail fibrous sheath.

AJ-FS9 is one of a new series of monoclonal antibodies (mAbs) raised by immunizing mice with isolated human sperm tail fibrous sheath (FS). Using indirect immunofluorescence (IIF) of human spermatozoa dried onto slides, the AJ-FS9 mAb reacted with the principal piece of occasional spermatozoa. Following their enzymatic treatment with trypsin, dispase or collagenase, but not sulphatase, all the spermatozoa were stained at their principal piece. The ultrastructural localization of the antigens to the FS was established by immunogold electron microscopy, which showed the distribution of gold particles on the FS outer surface of spermatozoa sequentially treated with 1% Triton and dispase; spermatozoa demembranated by Triton alone showed no reaction. For biochemical characterization, spermatozoa were lysed with 1% Triton, and the sperm pellet was run through a reducing sodium dodecyl sulphate-polyacrylamide gel electrophoresis, Western blotted and immunostained with AJ-FS9. The results showed the reaction of the antibody with three protein bands with molecular masses ranging between 46 and 56 kDa. IIF screening of human testicular cryostat sections with AJ-FS9 mAb showed its reactivity with occasional sperm tails; but following their dispase treatment, all spermatozoa were stained. The restricted staining of the assembled FS of maturing sperm tails indicated the late appearance of the antigens during spermatogenesis. The antibody did not react with sperm cell precursors or other cell types within/without the seminiferous tubules. Untreated and dispase-treated frozen sections of skin, oesophagus, tongue, liver, kidney, stomach, ileum or their blood vessels showed no reaction.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗

PubMed1993

Factors that may regulate assembly of the mammalian sperm tail deduced from a mouse t complex mutation.

A unique pattern of aberrant sperm development occurs in laboratory mice (Mus domesticus) that have been made homozygous for an allele of an autosomal gene, Hst-6s, derived from another mouse species, Mus spretus. During the abnormal spermiogenic process of these sterile animals, the sperm tail fails to assemble normally, although a bud develops at the site of the centriole in early spermatids. The bud enlarges during sperm development and eventually contains elements of a mature sperm tail. Tubulin assembles primarily into single microtubules rather than doublets. These singlets form a circular array that is not oriented relative to the centriole. While dense fibers form in association with the singlet microtubules, the fibrous sheath components accumulate in a single irregular mass. These observations suggest that microtubule doublets are required for the organization of an axoneme. In addition, while dense fibers can form normally in association with singlet microtubules, the fibrous sheath requires the axoneme as a substrate for normal organization.

Animals↗