cAMP-dependent phosphorylation associated with activation of motility of Ciona sperm flagella

Demembranated spermatozoa of Ciona do not become motile when provided with MgATP, unless their motility is activated in vivo before demembranation or unless the demembranated spermatozoa are activated in vitro with cAMP or with the catalytic subunit of a cAMP-dependent protein kinase. CAMP causes a greater than fivefold enhancement of ³²P incorporation by demembranated spermatozoa. Analysis by one-dimensional PAGE and autoradiography shows several axonemal protein bands that become ³²P-labeled during in vitro activation with cAMP and identifies protein bands whose labeling is specifically reduced if motility of the spermatozoa is activated before demembranation, suggesting that these proteins also become phosphorylated during activation of motolity in vivo. These phosphorylated proteins appear to include dynein heavy-chain components, but axonemal tubulin is not phosphorylated. Partially phosphorylated spermatozoa can be activated by an increase in KCI concentration, which appears to dissociate one phosphorylated component from the axoneme.     

Sperm glycoproteins of the boar,bull, rabbit,and ram: I. Acrosomal glycoproteins

Ejaculated spermatozoa of boars, bulls, rabbits, and rams were fixed with glutaraldehyde and embedded in glycolmethacrylate. Thin sections were treated with phosphotungstic acid at low pH in order to localize cellular glycoproteins stained by the PAS technique at the light microscope level. At the ultrastructural level the glycoproteins were segregated in the anterior segment of mature spermatozoa. The distribution of these glycoproteins in the anterior segment was not homogeneous; it appeared species-specific in detail, but as a rule, the maximum concentration was observed in a superficial layer, especially in the marginal thickening. The localization of other acrosomal components (eg, crystalline and basic proteins) is also reviewed. The origin and significance of the segregation of proteins and glycoproteins in the acrosome are discussed in relation to the fact that the acrosomal enzymes analyzed so far are glycoproteins.     

Crater defect in human spermatozoa

This report describes the “crater defect” in human spermatozoa, a malformation that consists of a nuclear and acrosomal invagination present in 100% of the cells, whereas tail structure and motility are fairly normal. The defect occurs during spermiogenesis. A possible concomitance with abnormalities in the microtubular apparatus involved in the sperm molding is discussed.     

Ultrastructural studies on the reproductive system of gyrocotylidea and amphilinidea (Cestoda): Spermatogenesis, spermatozoa, testes and vas deferens of Gyrocotyle

The ultrastructure of the vas deferens, testes, spermatogenesis and spermatozoa of Gyrocotyle urna and G. parvispinosa is described. The vas deferens is ciliated and syncytial. Within the testes primary spermatocytes arise from the primary spermatogonia by incomplete mitotic divisions; the primary spermatocytes undergo two meiotic divisions leading to spermatids. In early spermatids microtubules are formed at the cell periphery. Later the spermatozoal cytoplasm (the ‘middle-piece’) grows out and the two spermatozoal flagella with their typical 9 + ‘1’ axonemes are formed. During ciliogenesis the flagella are at an angle of about 60° to the axis of the middle-piece. The flagella are inserted into basal bodies terminating in striated rootlets. Subsequently, the nucleus and isolated mitochondria migrate into the central axis. The angle between the flagella and the axis decreases; the flagella are incorporated to form the spermatozoon. In mature spermatozoa no basal body or rootlet elements were found. The phylogeny of parasitic Platyhelminthes is discussed with respect to the evolution of spermatozoa. The reduction of the acrosinoid granules which are found in spermatozoa of free-living Platyhelminthes and the incorporation of the spermatozoal flagella into the sperm body constitute autapomorphies of the Neodermata (the parasitic Platyhelminthes). Included in the Cestoda because of several common derived characters, Amphilinidea and Gyrocotylidea are the only cestodes with spermatozoa containing mitochondria. Their absence in Cestoidea—all taxa with a six-hooked larva and other characteristics—is an autapomorphy of this group.     

Spontaneous continuous release of spermatozoa and its predawn surge in male passerine birds

Spontaneous, continuous release of morphologically normal spermatozoa occurs in males of species of passerine (order Passeriformes) birds that were examined. It was demonstrated and studied quantitatively in temporarily captive and isolated house sparrows and house finches by means of repetitive cloacal lavages and extraction of excreta. It is suggested that this phenomenon could be exploited to facilitate comparative and quantitative evaluations of release of spermatozoa in relation to diverse environmental, physiological, and social factors.     

Effect of compounds structurally related to taurine and of taurine uptake inhibitors on the motility of hamster sperm in vitro

Several taurine-related compounds, taurine antagonists and taurine uptake inhibitors were tested for their effect on hamster sperm motility in vitro. Hypotaurine was approximately three times more effective than taurine. N-methyltaurine and taurocyamine were less effective. Inactive taurine-related compounds were not effective blockers of taurine's spermtimulating activity. However, 1-(4-nitrophenyl)-2-dimethylaminomethyl-l-propenone, a taurine uptake inhibitor, completely suppressed sperm motility at a molar concentration equal to, or less than, that of the taurine added to the incubation medium and also suppressed the motility-sustaining action of the cumulus oophorus.     

Sperm glycoproteins of the boar,bull, rabbit,and ram: II. Surface glycoproteins and free acidic groups

Ejaculated spermatozoa of boars, bulls, rabbits, and rams were embedded in glycolmethacrylate and thin sections stained with phosphotungstic acid at low pH in order to observe the distribution of glycoproteins of the plasma membrane. Colloidal iron hydroxide was also used to detect the free acidic groups present on the sperm surface. Species-specific patterns of localizations of glycoproteins and linked negative charges were observed. The distribution was sometimes homogeneous as in bull, but generally heterogeneous in the other species. The significance of the results on sperm surface components and the practical interest to know their normal distribution are discussed.     

Interactions of aged gametes: In vitro fertilization using in vitro-aged sperm and in vivo-aged ova in the mouse

A study of varying combinations of in vitro-aged sperm and in vivo-aged ova at 3 hr intervals from 0–24 hr resulted in failures at different steps of the fertilization process during in vitro fertilization of mouse ova. Significant decreases caused by sperm aging, ova aging, and sperm × ova aging interaction were found in sperm penetration. Pronuclear formation was not affected by sperm aging and was enhanced by ova aging, and there was a significant effect of sperm × ova aging interaction. Sperm aging significantly influenced the prometaphase stage of the fertilization process. Therefore, it is suggested that the detrimental fertilization effects resulting from aging gametes are due to different mechanisms in sperm and ova, that these mechanisms are affected at different times, and that they affect different steps in the fertilization process.     

On the role of glucose in capacitation and acrosomal reaction of guinea pig sperm

In order to determine whether metabolizable sugars delayed capacitation of guinea pig spermatozoa, these cells were pre-incubated in Tyrode's pyruvate lactate glucose medium (T-PLG) or Tyrode's glucose solution (T-G). They were then transferred to minimal culture medium containing pyruvate and lactate (MCM-PL) and the occurrence of acrosomal reactions (AR) was determined by light microscopic observations of wet mount aliquots. The percentage of acrosomal reactions was quantitated in fixed samples and occurrence of a true AR was confirmed by electron microscopy. Activated acrosome-reacted spermatozoa were observed within 5 min when cells were transferred to MCM-PL solution, after preincubating them for 60–120 min either in T-PLG or T-G media. By 15 min in MCM-PL the percentage of acrosome-reacted spermatozoa reached values similar to those obtained in cells pre-incubated from the beginning in MCM-PL medium (P > 0.05 in both) but significantly different from T-PLG and T-G controls (P < 0.0005 in both). The acrosomal reaction was external calcium dependent and independent of the Tyrode's media pH ranging from 7.2 to 8.0. The results obtained suggested that capacitation occurred in T-PLG and that it was not delayed by glucose; the results also suggested that capacitation could occur within a short time with glucose as the only exogenous substrate, but that the acrosome reaction could have been arrested by a glucose metabolite. Data are presented which suggest that intracellular levels of glucose-6-phosphate (as 2-deoxyglucose-6-phosphate)could play a key role in the expression of the acrosome reaction in sperm already able to perform it. A new hypothesis is suggested for the development of the fertilizing potential of guinea pig sperm when in the female genital tract.