RESUMO
The study investigated midpiece defects in sperm from a 5-year-old Brangus bull with a high rate of semen batch rejection, due to morphologically abnormal sperm, with no reduction in sperm kinematics. A comprehensive evaluation was conducted over a 16-month period, involving 28 ejaculates. Notably, despite the high proportion of midpiece defects (average 37.73%, from 3% to 58%), the study revealed stable sperm production, with no discernible differences in the kinematic data before and after cryopreservation. Electron microscopy identified discontinuities in the mitochondrial sheath, characteristic of midpiece aplasia (MPA). The anomalies were attributed to be of genetic origin, as other predisposing factors were absent. Additionally, the electron microscopy unveiled plasma membrane defects, vacuoles and chromatin decondensation, consistent with previous findings linking acrosome abnormalities with midpiece defects. The findings underscored the necessity of conducting thorough laboratory evaluations before releasing cryopreserved semen for commercialization. Despite substantial morphological alterations, the initial semen evaluation data indicated acceptable levels of sperm kinematics, emphasizing the resilience of sperm production to severe morphological changes. This case report serves as a contribution to the understanding of midpiece defects in bull sperm, emphasizing the need for meticulous evaluation and quality control in semen processing and commercialization.
Assuntos
Criopreservação , Análise do Sêmen , Preservação do Sêmen , Espermatozoides , Masculino , Animais , Criopreservação/veterinária , Bovinos , Preservação do Sêmen/veterinária , Análise do Sêmen/veterinária , Espermatozoides/anormalidades , Espermatozoides/fisiologia , Fenômenos Biomecânicos , Peça Intermédia do Espermatozoide , Motilidade dos Espermatozoides , AcrossomoRESUMO
BACKGROUND: Bulls are of great importance in the productive chain and for this reason they should have a good semen quality. There is no doubt that sperm morphology is very important to bull fertility, although little is known about how exactly the abnormal morphologies may affect sperm functions. OBJECTIVES: To detail the morphological description of the aplastic midpiece defect (AMD), as well as to understand its consequences for male fertility based on membrane and acrosome status, mitochondrial membrane potential and DNA integrity parameters. MATERIALS AND METHODS: The bulls were divided into two groups: control, consisting of satisfactory potential breeders (n = 3); and AMD, consisting of unsatisfactory potential breeders with a high percentage of AMD (n = 3). Bulls were evaluated by the breeding soundness evaluation; five ejaculates were collected from each animal and analyzed by flow cytometry. RESULTS: Spermatozoa from AMD group exhibited lower sperm motility and vigor (p < 0.05). In addition, it also exhibited lower mitochondrial membrane potential (p < 0.05), a higher percentage of spermatozoa with DNA fragmentation (p < 0.05), lower acrosome and plasma membrane integrity (p < 0.05), and higher lipid bilayer sperm membrane disorganization (p < 0.05) in comparison with control bulls. DISCUSSION: These findings may be due to oxidative stress and a reduction of the energy production capacity in addition to an alteration in the structural composition of the sperm cell. Moreover, semen with a high percentage of AMD may also be undergoing apoptosis. CONCLUSION: Bulls with a high percentage of AMD in their semen are not suitable for reproduction. Furthermore, it suggests there is a putative genetic basis for this sperm defect.
Assuntos
Bovinos , Fertilidade , Espermatozoides/anormalidades , Animais , Masculino , Peça Intermédia do Espermatozoide/patologia , Espermatozoides/fisiologiaRESUMO
Animals with external fertilization, as amphibians, store their sperm in a quiescent state in the testis. When spermatozoa are released into natural fertilization media, the hypotonic shock triggers activation of sperm motility. Rhinella (Bufo) arenarum sperm are immotile in artificial seminal plasma (ASP, resembling testicular plasma tonicity) but acquire in situ flagellar beating upon dilution. However, if components from the egg shelly coat are added to this medium, motility shifts to a progressive pattern. Recently, we have shown that the signal transduction pathway required for in situ motility activation involves a rise in intracellular cAMP through a transmembrane adenylyl cyclase and activation of PKA, mostly in the midpiece and in the sperm head. In this report, we demonstrate that activation of calcineurin (aka PP2B and PPP3) is required for the shift from in situ to progressive sperm motility. The effect of calcineurin is manifested by dephosphorylation of PKC substrates, and can be promoted by intracellular calcium rise by Ca(2+) ionophore. Both phosphorylated PKC substrates and calcineurin localized to the flagella, indicating a clear differentiation between compartmentalization of PKA and calcineurin pathways. Moreover, no crosstalk is observed between these signaling events, even though both pathways are required for progressive motility acquisition as discussed.
Assuntos
Proteínas de Anfíbios/metabolismo , Bufo arenarum/metabolismo , Calcineurina/metabolismo , Proteína Quinase C/metabolismo , Transdução de Sinais , Motilidade dos Espermatozoides , Espermatozoides/enzimologia , Animais , Inibidores de Calcineurina , Ionóforos de Cálcio/farmacologia , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Inibidores Enzimáticos/farmacologia , Flagelos/enzimologia , Masculino , Pressão Osmótica , Fosforilação , Transdução de Sinais/efeitos dos fármacos , Peça Intermédia do Espermatozoide/enzimologia , Motilidade dos Espermatozoides/efeitos dos fármacos , Cauda do Espermatozoide/enzimologia , Espermatozoides/efeitos dos fármacos , Especificidade por SubstratoRESUMO
Hylodinae leptodactylids (sensu Lynch 1971) form a group of diurnal frogs, which is hypothesized on the basis of morphological traits to be the closest relatives of the dendrobatid frogs. Our study describes ultrastructural characteristics of sperm from three hylodine species (Hylodes phyllodes, Crossodactylus sp. n. and Megaelosia massarti) to reassess the intergeneric relationships within the Hylodinae, as well as the supposed relationship between the Hylodinae and Dendrobatidae. The ultrastructure of the sperm is very similar among the three species and is indicative of its conserved nature within the Hylodinae. The structure of the acrosomal complex was very similar to that of other leptodactylid species, to most of the remaining species included in the Bufonoidea lineage, and also to that observed in the dendrobatid species examined so far. Since such a structure has been considered a plesiomorphic trait, it contributes little to our understanding of the relationships between the Hylodinae and Dendrobatidae. The flagellar apparatus of Crossodactylus sp. n. is very similar to that of most leptodactylids. The sperm of Megaelosia massarti and Hylodes phyllodes display a distinctive condition in their axial and juxtaxonemal fibers. This distinctive flagellar condition expands the already known variability in sperm structure within the Leptodactylidae.
Assuntos
Anuros/classificação , Espermatozoides/ultraestrutura , Acrossomo/ultraestrutura , Animais , Anuros/anatomia & histologia , Evolução Biológica , Núcleo Celular/ultraestrutura , Geografia , Masculino , Filogenia , Peça Intermédia do Espermatozoide/ultraestrutura , Cauda do Espermatozoide/ultraestrutura , Espermatozoides/classificaçãoRESUMO
We describe, for the first time, the sperm ultrastructure of the two genera of Pseudinae. Based on sperm ultrastructure, the five species herein examined can be separated into three groups: one containing Pseudis paradoxa, P. bolbodactyla, and P. tocantins, the second containing P. minuta, and the third containing Lysapsus laevis. The midpiece is similar in all species and auxiliary fibers and the undulating membrane are absent. In Pseudis a subacrosomal cone and a multilaminar structure (P. minuta) or a granular material (P. paradoxa group) are seen above the nucleus. Lysapsus laevis has only remnants of the subacrosomal cone. All species have peripheral fibers associated with the outer doublets of the axoneme. We tested the hypothesis of correlation between the presence of an undulating membrane and fertilization environments in anurans using a concentrated changes test (CCT) based on the Hay et al. (Mol Biol Evol 1995;12:928-937) hypothesis of phylogenetic relationships among anuran families. Only a subset of the resolved topologies derived from the Hay et al. (1995) cladogram, where Ranoidea is the sister-group of Sooglossidae, produced significant probabilities of the CCT. Therefore, support for the correlation between sperm ultrastructure and fertilization environments in anurans is, at best, equivocal.