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PubMed1979

Fate of fragments and properties of translocations of holokinetic chromosomes after X-irradiation of mature sperm of Tetranychus urticae Koch (Acari, Tetranychidae).

After irradiation of mature sperm in males of Tetranychus urticae, early cleavage stages were scored for chromosome fragments. As expected from the presumed holokinetic nature of the chromosomes, the majority (94.29%) of the fragments pass mitosis without difficulty. A minority of the fragments is affected by loss (4.76%) or missegregation (0.95%), leading to loss of fragments from cells in a large fraction of fragment-containing eggs after a few divisions. Lethality induced by the irradiation treatment can probably be ascribed to these losses. When meiotic configurations of F1 females are analysed, translocations turn out to be the most frequent type of aberration, often accompanied by recessive lethal mutations, thus adding an extra amount of lethality to the already high number of non-viable haploid offspring of heterozygous F1 females. The frequently occurring infecundity of the F1 females may be caused by mechanical problems in early stages of meiosis (before oviposition), when multivalents are not able to perform the specific turning movements typical for this type of chromosome. According to calculations, univalents in meiotic stages are thought to represent translocated chromosomes rather than independent fragments.

Acari↗
PubMedDate not supplied

Expression and phosphorylation of mitogen-activated protein kinases during spermatogenesis and epididymal sperm maturation in mice.

The expression and phosphorylation/dephosphorylation of mitogen-activated protein (MAP) kinases during mouse spermatogenesis and epididymal sperm maturation have been investigated by immunoblotting and immunohistochemical staining with commercially available anti-ERK2 and anti-Active MAPK antibodies. Two forms of MAP kinases, p42ERK2 and p44ERK1, were expressed in a similar amount in spermatogenic cells at different stages. ERK1 and ERK2 were phosphorylated (activated) in early spermatogenic cells from primitive spermatogonia to zygotene primary spermatocytes, while only a small quantity of phosphorylated MAP kinases could be detected in pachytene primary spermatocytes and spermatids. MAP kinase activity in primative spermatogonia and preleptotene primary spermatocytes was the highest among spermatogenic cells. ERK1 and ERK2 were also present in epididymal spermatozoa, and their phosphorylation was increased while spermatozoa pass through epididymis and vas deferens for maturation. It would appear that MAP kinase activation may contribute to the mitotic proliferation of primative spermatogonia, an early phase of spermatogenic meiosis, and, later, sperm motility acquirement.

Animals↗
PubMed1989

Expression and topographical localization of cell surface fucosyltransferase activity during epididymal sperm maturation in the mouse.

We have demonstrated previously that spermatogenic cells in the mouse testis have high levels of fucosyltransferase activity. Furthermore, a significant portion of this activity has been localized to the cell surface (Millette et al.: Cell Biology of the Testis and Epididymis, 1987). Differential expression of fucosyltransferases and their function as ecto-enzymes may be important in the processes of sperm maturation and fertilization in mammals. Accordingly, here we report the activity levels of fucosyltransferase (FT) in spermatozoa isolated from the mouse caput and cauda epididymides. Calculated on a per cell basis, spermatozoa from the caput epididymis have significantly more FT activity than do spermatozoa from the cauda epididymis (18.07 +/- 2.2 pmol/million cells compared with 2.8 +/- 0.09 pmol/million cells). Furthermore, caput sperm exhibit a more significant increase in FT activity when assayed in the presence of Nonidet P-40. Calculated on the basis of cell surface area, however, FT activity remains constant on the head portion of spermatozoa isolated from all portions of the male reproductive tract and from capacitated spermatozoa. Measurements of FT activity in extracts of isolated sperm tails from cells at different stages of maturation indicate a greatly diminished activity in tails from sperm in the cauda epididymis. The total sperm surface area is composed predominantly of the plasma membrane surrounding the flagellar apparatus. Therefore, our data demonstrate that FT activity is retained selectively on the different topological regions of sperm, with losses during sperm maturation in the epididymis being restricted to the tail segment. Maintenance of high levels of FT activity of the plasma membranes of the mouse sperm head raise the possibility that FT is indeed involved in some aspects of sperm-egg recognition.

Animals↗
PubMed2006

Glycan-modifying enzymes in luminal fluid of the mammalian epididymis: an overview of their potential role in sperm maturation.

Testicular spermatozoa and those present within the proximal regions of the epididymis are unable to bind to the zona pellucida, the extracellular coat that surrounds the oocyte, and fertilize the egg. They acquire progressive motility and fertilizing ability during passage through the epididymis. Mammalian spermatozoa undergo biochemical and physiological changes during epididymal transit that are collectively termed epididymal maturation. The process involves several intracellular and extracellular changes in the spermatozoon, including remodeling of the sperm plasma membrane and modifications of glycan moieties of the sperm surface glycoconjugates. Two sets of glycan-modifying enzymes, namely glycohydrolases that cleave sugar residues and glycosyltransferases that add sugar residues to the existing glycoconjugates, are present in the epididymal luminal fluid that surrounds spermatozoa. Thus, it is reasonable to expect that glycan chains present on the sperm surface will interact with these glycan-modifying enzymes in the epididymal fluid. In this article, I have attempted to summarize and present an overview on the potential role of these glycan-modifying enzymes in sperm maturation.

Animals↗
PubMed1968

DNA organization in the mature sperm of several orthoptera by the method of polarized fluorescence microscopy.

Mature sperm of Acheta domesticus, Acheta assimilis, Nemobius fasciatus, Nemobius confusus, Melanoplus femur-rubrum, Romalea microptera, Scudderia curvicauda, and Ceuthophilus nigricans were examined for DNA configuration by means of polarized fluorescence microscopy. In all cases, the results suggest that the DNA lies in unsupercoiled array, predominantly parallel to the elongate sperm head axes. Detailed calculations of the factors influencing the degree of polarization of the fluorescent emission from supercoiled DNA are contained in an appendix.

Animals↗
PubMed1978

Arginine evaluation to verify sperm maturation in man.

A modified version of Sakaguchi's histochemical reaction is proposed for the evaluation of arginine content in spermatozoa as an index of sperm maturation. Results obtained with this procedure, compared with DNA and basic nuclear proteins determinations in the sperm cells from normal subjects and from patients with oligospermia, appear to confirm the usefulness of this technique.

Adult↗
PubMed2002

In vitro cultivation of spermatocysts to matured sperm in the silkworm Bombyx mori.

Bombyx spermatogonia are bipotential, producing nucleate eupyrene sperm and anucleate apyrene sperm. An in vitro cultivation of spermatocysts of Bombyx mori from spermatocytes to matured sperm was established. The present experiment made clear that: (i) spermatocysts must be isolated; (ii) constant shaking at 45 r.p.m. was necessary; and (iii) the addition of Bombyx hemolymph (BH) was indispensable for successful cultivation. In the absence of BH, spermatogenesis proceeded normally for 2 or 3 days and, thereafter, spermatocytes and sperm bundles began to degenerate. The best results for normal eupyrene spermatogenesis were obtained when culture medium containing BH of the corresponding stage was used in every exchange of the medium at 72 h intervals. None or only a small number of apyrene sperm bundles was produced by this culture system when spermatocysts from larval testes were used, although eupyrene spermatogenesis proceeded normally to form matured, or squeezed, sperm bundles.

Animals↗
PubMed1998

Role of epididymal secretory proteins in sperm maturation with particular reference to the boar.

This review considers the role of proteins secreted by the epididymis on post-testicular sperm maturation and storage. Two-dimensional gels show that 150 to 200 proteins are secreted into the epididymal lumen. Most are secreted in relatively small amounts; in rams, for example, fewer than ten contribute 90% of the total secretion and only two contribute 52% of the total protein secreted. Most of the proteins are confined to specific regions of the epididymis. The changing pattern of protein secretion along the epididymis corresponds to change in surface protein on spermatozoa, but no epididymal proteins have been identified that appear to be directly involved in modifying the sperm membrane. Most of the major proteins that have been identified seem to be playing a homeostatic role in maintaining the epididymal milieu for spermatozoa.

Animals↗
PubMed1991

[Comparison of frequencies of complete and incomplete translocations induced in mature sperm of Drosophila].

A frequency of induction of translocations taking place in mature sperm of Drosophila between heterochromatic portions of the 2L compound and 2R acrocentric was estimated to be 9.62 X 10(-3). This value is being compared with the previously estimated frequency of incomplete translocations in this system which is (2.5-2.9) X 10(-3). The ratio of frequencies of complete and incomplete translocations obtained was intermediate between the Panshin data, on the one hand, and those of Muller and Hershkowitz, on the other. The reasons for these discrepancies are under discussion. Based on the value obtained for this ratio, the probability of reunion of chromosome break (q) is calculated to be 0.79.

Animals↗
PubMed1998

Extratesticular sperm maturation in the brush-tail possum, Trichosurus vulpecula.

The changes in distribution of protein and sugar components in, and on, the plasmalemma of the spermatozoon during epididymal transit of a marsupial, the brush-tail possum, Trichosurus vulpecula, are described. Freeze-fracture studies indicate a change in organization of plasmalemma intramembranous particles of both the head and midpiece of the tail as the spermatozoa pass from the caput to cauda epididymides. Staining with fluorescein isothiocyanate (FITC)-lectins shows, that heads of caput spermatozoa stain with Con A, WGA, RCA120, LCA and JAC, whereas those from the cauda epididymides stain only with LCA and JAC, thus suggesting that N-acetyl-beta-D-glucosamine, alpha-D-glucose, or beta-D-galactose may either become lost or masked during epididymal transit. A reduction of alpha-D-mannose is also suggested. Collectively these results show that the plasmalemma of the spermatozoon of at least this marsupial species undergoes both protein and saccharide modification during transit of the epididymis. How these findings relate to sperm maturation in preparation for sperm-egg binding has yet to be determined.

Acetylglucosamine↗
PubMed1979

The formation of disulfide bonds in human protamines during sperm maturation.

The disulfide contents of human sperm heads, as measured by reduction to the sulfhydryls and subsequent alkylation with 14C-iodoacetamide, increase about 2-fold during the sperm passage from the caput to caudal epididymides. Majority of the increased disulfides resides in the human protamine fractions.

Chromatin↗
PubMed2005

Evaluation of boar sperm maturation after co-incubation with caput, corpus and cauda epididymal cultures [corrected].

Boar sperm from the proximal caput epididymis were co-incubated with 1, 4, 7, 10 and 14-day old caput, corpus and cauda epididymal cultures for 24, 48 and 72 h. Boar kidney epithelial cells (LLC-PK1) and ECM alone were used as negative controls. Sperm motility, morphology and membrane integrity were studied to evaluate boar sperm maturation in vitro. Our results showed that epithelial cell monolayers (10, 14-day old) create a suitable microenvironment for the survival of proximal caput sperm and the maintenance of sperm motility over a 72 h period. Moreover, corpus epididymal tubule fragments in culture (1, 4-day old) are capable of promoting the migration of the cytoplasmic droplet along the sperm tail after 24h of co-incubation.

Animals↗
PubMed1980

Evidence supporting the existence of sperm maturation in the human epididymis.

Zona-free hamster oocytes were used to evaluate the penetrating capacity of spermatozoa recovered from the caput, corpus and cauda segments of 5 human epididymides. The ability of spermatozoa to bind tightly to oocytes increased in spermatozoa from successive segments. However, only spermatozoa recovered from the cauda epididymidis were able to penetrate the oocytes (26%). These results suggest that, in man, a gradual process of sperm maturation occurs in the epididymis, as has been observed in numerous other species of mammals.

Adult↗
PubMed2002

Induction of sperm maturation in vitro in epididymal cell cultures of the tammar wallaby (Macropus eugenii): disruption of motility initiation and sperm morphogenesis by inhibition of actin polymerization.

A sperm-epididymal cell co-culture was shown to be capable of inducing the in vitro maturation of spermatozoa from a marsupial species, the tammar wallaby (Macropus eugenii). This system was able to maintain wallaby epididymal epithelial cells in vitro for more than 2 months. The system also enabled immature wallaby spermatozoa to differentiate from a T-shaped to a streamlined form, accompanied by the development of progressive motility after co-culture with epididymal cell monolayers that had been cultured for 7 days. The addition of inhibitors of actin polymerization (latrunculin A or B) to the co-culture system showed that wallaby sperm maturation was impaired by the interruption of actin organization within the immature spermatozoa. These results indicate that actin filaments play a significant role in sperm transformation during post-testicular maturation in marsupials. These observations also indicate that the marsupial co-culture system has the potential to greatly increase understanding of sperm-epididymal cell interactions and the mechanism of sperm maturation in these species.

Actins↗
PubMed1976

Effects of epididymal occlusion on sperm maturation in the hamster.

Hamster epididymal spermatozoa were isolated in the caput, corpus and cauda regions for one, two and three days. Sperm suspensions from these regions were assessed for morphology, motility, viability; and for fertility by A.I. The ability to capacitate was tested by checking for acrosome reactions when the sperm were cultured under defined capacitating conditions at 37 degrees C in vitro. Normal, mature cauda sperm were highly fertile (overall 77% of ova fertilized) and showed 50-80% incidence of acrosome reactions after six hours in culture. Isolation for up to three days had no effect. Immature sperm from the caput and corpus were poorly motile, infertile, and did not manifest an acrosome reaction. Isolation for one and two days produced improvements in motility, and distal migration of the cytoplasmic droplet skin to normal maturation, however the sperm remained infertile and did not capacitate in vitro. Survival after three days isolation was poor. Thus the development of fertilizing ability in hamster epididymal spermatozoa is closely related to the ability to manifest an acrosome reaction in vitro; however it is only poorly correlated with motility and morphology. Completion of sperm maturation in this species appears to require the environment of the cauda epididymidis.

Animals↗
PubMed1999

Dual function of the selenoprotein PHGPx during sperm maturation.

The selenoprotein phospholipid hydroperoxide glutathione peroxidase (PHGPx) changes its physical characteristics and biological functions during sperm maturation. PHGPx exists as a soluble peroxidase in spermatids but persists in mature spermatozoa as an enzymatically inactive, oxidatively cross-linked, insoluble protein. In the midpiece of mature spermatozoa, PHGPx protein represents at least 50 percent of the capsule material that embeds the helix of mitochondria. The role of PHGPx as a structural protein may explain the mechanical instability of the mitochondrial midpiece that is observed in selenium deficiency.

Animals↗
PubMed1991

[Incomplete translocations induced in mature sperm of Drosophila].

Frequencies of incomplete translocations in subcentromeric heterochromatin induced by gamma-rays in mature sperm were estimated in the "two right acrocentrics and left compound" system of Drosophila chromosome 2. The value obtained at 3000R was (2.5-2.9) X 10(-3). Apart from incomplete translocations leading to formation of new metacentrics, acrocentrics were also formed. It is suggested that they appear via reunion of fragments after replication of paternal chromosomes. Incomplete translocation were shown to be formed as a result of loss of centric heterochromatin fragment of acrocentric and acentric arm of the compound, as opposed to formation, due to loss of acentric heterochromatin fragment of acrocentric and centric fragment of the compound. Analysis of the dose-effect curve for half-translocations show that the latter are two hit events.

Animals↗
PubMed1994

Molecular characterization of human TRPM-2/clusterin, a gene associated with sperm maturation, apoptosis and neurodegeneration.

The TRPM-2/clusterin gene and its cognate protein has been characterized in a number of species. Although the functional role, or roles, of the TRPM-2/clusterin protein remains to be firmly established, the gene has been implicated in a variety of physiological processes, including sperm maturation, lipid transport, membrane remodelling and inhibition of the complement cascade. TRPM-2/clusterin is induced de novo during the regression of the prostate and other hormone-dependent tissues after hormone ablation, and is over-expressed in several human neurodegenerative diseases including Alzheimer's disease, epilepsy and retinitis pigmentosa. We describe the genomic structure of the human TRPM-2/clusterin gene which is organized into nine exons, ranging in size from 47 bp (exon I) to 412 bp (exon V), spanning a region of 16,580 bp. Comparison with sequences registered in the databases shows that it has extensive similarity to the human protein designated as SP-40,40 or complement-lysis inhibitor (CLI), a protein that appears to block the membrane-attack complex of complement. However, the cDNA sequences reported for SP-40,40 and CLI diverge significantly in the 5' untranslated region of the mRNA (coded for by exon I), raising the possibility that the TRPM-2/clusterin gene is present in the human genome as a small multi-gene family or that there are several alternate exon I sequences in the TRPM-2 gene. Southern analysis and fluorescent in situ hybridization suggest that the clusterin gene is a single-copy gene, and that, if alternative exon I sequences are present in the genome, they lie outside of the lambda clones that have been characterized. Analysis of the promoter region of the human TRPM-2/clusterin gene shows many similarities to the rat TRPM-2/clusterin promoter including a putative control region containing several potential regulatory elements that may regulate the complex tissue-specific control of the gene which must be constitutively expressed in some tissues but is inducible in others.

Amino Acid Sequence↗