RESUMEN
We examined whether a tool for determining Johnsen scores automatically using artificial intelligence (AI) could be used in place of traditional Johnsen scoring to support pathologists' evaluations. Average precision, precision, and recall were assessed by the Google Cloud AutoML Vision platform. We obtained testicular tissues for 275 patients and were able to use haematoxylin and eosin (H&E)-stained glass microscope slides from 264 patients. In addition, we cut out of parts of the histopathology images (5.0 × 5.0 cm) for expansion of Johnsen's characteristic areas with seminiferous tubules. We defined four labels: Johnsen score 1-3, 4-5, 6-7, and 8-10 to distinguish Johnsen scores in clinical practice. All images were uploaded to the Google Cloud AutoML Vision platform. We obtained a dataset of 7155 images at magnification 400× and a dataset of 9822 expansion images for the 5.0 × 5.0 cm cutouts. For the 400× magnification image dataset, the average precision (positive predictive value) of the algorithm was 82.6%, precision was 80.31%, and recall was 60.96%. For the expansion image dataset (5.0 × 5.0 cm), the average precision was 99.5%, precision was 96.29%, and recall was 96.23%. This is the first report of an AI-based algorithm for predicting Johnsen scores.
Asunto(s)
Azoospermia/diagnóstico , Histocitoquímica/normas , Infertilidad Masculina/diagnóstico , Aprendizaje Automático , Túbulos Seminíferos/patología , Espermatocitos/patología , Adulto , Automatización de Laboratorios , Azoospermia/patología , Colorantes , Eosina Amarillenta-(YS) , Hematoxilina , Histocitoquímica/métodos , Humanos , Infertilidad Masculina/patología , Masculino , Túbulos Seminíferos/ultraestructura , Espermátides/patología , Espermátides/ultraestructura , Espermatocitos/ultraestructura , Espermatogonias/patología , Espermatogonias/ultraestructuraRESUMEN
The process of spermatogenesis and spermatozoon morphology was characterized from a deep-sea bivalve, Calyptogena pacifica (Vesicomyidae, Pliocardiinae), a member of the superfamily Glossoidea, using light and electron microscopy. Spermatogenesis in C. pacifica is generally similar to that in shallow-water bivalves but, the development of spermatogenic cells in this species has also some distinguishing features. First proacrosomal vesicles are observed in early spermatocytes I. Although, early appearance of proacrosomal vesicles is well known for bivalves, in C. pacifica, these vesicles are associated with electron-dense material, which is located outside the limiting membrane of the proacrosomal vesicles and disappears in late spermatids. Another feature of spermatogenesis in C. pacifica is the localization of the axoneme and flagellum development. Early spermatogenic cells lack typical flagellum, while in spermatogonia, spermatocytes, and early spermatids, the axoneme is observed in the cytoplasm. In late spermatids, the axoneme is located along the nucleus, and the flagellum is oriented anteriorly. During sperm maturation, the bent flagellum is transformed into the typical posteriorly oriented tail. Spermatozoa of C. pacifica are of ect-aqua sperm type with a bullet-like head of about 5.8 µm in length and 1.8 µm in width, consisting of a well-developed dome-shaped acrosomal complex, an elongated barrel-shaped nucleus filled with granular chromatin, and a midpiece with mainly four rounded mitochondria. A comparative analysis has shown a number of common traits in C. pacifica and Neotrapezium sublaevigatum.
Asunto(s)
Bivalvos/fisiología , Bivalvos/ultraestructura , Espermatogénesis , Animales , Masculino , Espermátides/ultraestructura , Espermatocitos/ultraestructura , Espermatogonias/ultraestructura , Espermatozoides/ultraestructuraRESUMEN
Spermatogenesis is important for male fertility, but has not been well-studied in Opsariichthys bidens, an economically important freshwater fish in China. In this study, there was investigation of the cytological features of spermatogenesis in O. bidens using light microscopy, transmission electron microscopy, and immunofluorescence detection of microtubules. O. bidens has tubular testis. Spermatogenesis in O. bidens is of the cystic type, in which the spermatogenic cells develop into spermatozoa in cysts. There was asynchronous development of primary spermatocytes within a single cyst. Spermiogenesis was classified as Type I, which develops into a Type I aquasperm with an oval nucleus, a small and simple midpiece, a flagellum and no acrosome. There was a nuage in spermatogonia, spermatocytes, and spermatids in different developmental stages of spermatids which may have important functions in fish spermatogenesis. Furthermore, microtubule dynamics may be involved in spermatid reshaping, material transport, and polar distribution of organelles during spermiogenesis.
Asunto(s)
Cyprinidae/fisiología , Espermatogénesis/fisiología , Espermatozoides/citología , Testículo/citología , Animales , Acuicultura , China , Citoesqueleto/fisiología , Agua Dulce , Masculino , Meiosis , Microscopía Electrónica , Microtúbulos/ultraestructura , Células de Sertoli/citología , Células de Sertoli/ultraestructura , Espermátides/citología , Espermátides/ultraestructura , Espermatocitos/citología , Espermatocitos/ultraestructura , Espermatogonias/citología , Espermatogonias/ultraestructura , Espermatozoides/ultraestructura , Testículo/ultraestructuraRESUMEN
Meiosis produces four haploid cells after two successive divisions in sexually reproducing organisms. A critical event during meiosis is construction of the synaptonemal complex (SC), a large, protein-based bridge that physically links homologous chromosomes. The SC facilitates meiotic recombination, chromosome compaction, and the eventual separation of homologous chromosomes at metaphase I. We present experiments directly measuring physical properties of captured mammalian meiotic prophase I chromosomes. Mouse meiotic chromosomes are about ten-fold stiffer than somatic mitotic chromosomes, even for genetic mutants lacking SYCP1, the central element of the SC. Meiotic chromosomes dissolve when treated with nucleases, but only weaken when treated with proteases, suggesting that the SC is not rigidly connected, and that meiotic prophase I chromosomes are a gel meshwork of chromatin, similar to mitotic chromosomes. These results are consistent with a liquid- or liquid-crystal SC, but with SC-chromatin stiff enough to mechanically drive crossover interference.
Asunto(s)
Cromatina/metabolismo , Cromosomas de los Mamíferos , Profase Meiótica I , Espermatocitos , Animales , Cromatina/ultraestructura , Cromosomas de los Mamíferos/metabolismo , Cromosomas de los Mamíferos/ultraestructura , Técnica del Anticuerpo Fluorescente , Geles , Masculino , Ratones , Ratones Endogámicos C57BL , Espermatocitos/metabolismo , Espermatocitos/ultraestructuraRESUMEN
The aim of this study was to analyse spermatogenesis in the African butterflyfish, Pantodon buchholzi, using transmission electron microscopy and scanning electron microscopy. P. buchholzi is the most basal teleost that exhibits insemination and produces a highly complex introsperm with the most elongate midpiece known in teleost fishes. Their early stages (spermatogonia and spermatocytes) do not differ greatly from those of other fishes, with the exception of Golgi apparatus degradation appearing as spindle-shaped bodies (SSBs). In round, early spermatids, the development of the flagellum begins after the migration of the centriolar complex towards the nucleus. Later, the elongation of the midpiece coincides with the displacement of the mitochondria and their fusion to produce nine mitochondrial derivatives (MDs). In these spermatids, the nucleus is situated laterally to the midpiece, with condensing chromatin in the centre of the nucleus. Within the midpiece, the flagellum is located within a cytoplasmic canal and is surrounded by a cytoplasmic sleeve containing fibres, MDs and a great amount of cytoplasm located on one side. During the next phase, nuclear rotation, the highly condensed chromatin is displaced to a position above the centriolar apparatus, whereas chromatin-free nucleoplasm is transferred to the cytoplasm. Later, this nucleoplasm, still surrounded by the nuclear membrane, is eliminated into the cyst lumen as the nucleoplasmic packet. Within the highly elongate spermatids, other excess organelles (SSBs, endoplasmic reticulum and mitochondria) are eliminated as residual bodies (RBs). Fully developed spermatozoa, which contain conical-shaped nuclei, eventually coalesce to form unencapsulated sperm packets (spermatozeugmata) that are surrounded by RBs at the level of the extremely elongate midpieces. Later, RBs are removed at the periphery of the cyst by means of phagocytosis by Sertoli cells.
Asunto(s)
Peces/fisiología , Espermatogénesis/fisiología , Espermatozoides/ultraestructura , Animales , Núcleo Celular/ultraestructura , Citoplasma/ultraestructura , Flagelos/ultraestructura , Masculino , Microscopía Electrónica de Rastreo , Microscopía Electrónica de Transmisión , Mitocondrias/ultraestructura , Espermátides/ultraestructura , Espermatocitos/ultraestructura , Espermatogonias/ultraestructuraRESUMEN
Previously, we have shown that human sperm Prohibitin (PHB) expression is significantly negatively correlated with mitochondrial ROS levels but positively correlated with mitochondrial membrane potential and motility. However, the possible role of PHB in mammalian spermatogenesis has not been investigated. Here we document the presence of PHB in spermatocytes and its functional roles in meiosis by generating the first male germ cell-specific Phb-cKO mouse. Loss of PHB in spermatocytes resulted in complete male infertility, associated with not only meiotic pachytene arrest with accompanying apoptosis, but also apoptosis resulting from mitochondrial morphology and function impairment. Our mechanistic studies show that PHB in spermatocytes regulates the expression of STAG3, a key component of the meiotic cohesin complex, via a non-canonical JAK/STAT pathway, and consequently promotes meiotic DSB repair and homologous recombination. Furthermore, the PHB/JAK2 axis was found as a novel mechanism in the maintenance of stabilization of meiotic STAG3 cohesin complex and the modulation of heterochromatin formation in spermatocytes during meiosis. The observed JAK2-mediated epigenetic changes in histone modifications, reflected in a reduction of histone 3 tyrosine 41 phosphorylation (H3Y41ph) and a retention of H3K9me3 at the Stag3 locus, could be responsible for Stag3 dysregulation in spermatocytes with the loss of PHB.
Asunto(s)
Código de Histonas , Meiosis/genética , Proteínas Represoras/fisiología , Espermatocitos/metabolismo , Espermatogénesis/genética , Animales , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Línea Celular , Emparejamiento Cromosómico , Epigenoma , Histonas/metabolismo , Recombinación Homóloga , Infertilidad/genética , Janus Quinasa 2/metabolismo , Quinasas Janus/metabolismo , Masculino , Ratones , Ratones Noqueados , Mitocondrias/fisiología , Mitocondrias/ultraestructura , Fase Paquiteno , Fosforilación , Prohibitinas , Proteínas Represoras/genética , Proteínas Represoras/metabolismo , Factores de Transcripción STAT/metabolismo , Transducción de Señal , Espermatocitos/enzimología , Espermatocitos/ultraestructura , Testículo/metabolismoRESUMEN
Intraflagellar transport (IFT) is an evolutionarily conserved mechanism that is indispensable for the formation and maintenance of cilia and flagella; however, the implications and functions of IFT81 remain unknown. In this study, we disrupted IFT81 expression in male germ cells starting from the spermatocyte stage. As a result, homozygous mutant males were completely infertile and displayed abnormal sperm parameters. In addition to oligozoospermia, spermatozoa presented dysmorphic and nonfunctional flagella. Histological examination of testes from homozygous mutant mice revealed abnormal spermiogenesis associated with sloughing of germ cells and the presence of numerous multinucleated giant germ cells (symblasts) in the lumen of seminiferous tubules and epididymis. Moreover, only few elongated spermatids and spermatozoa were seen in analyzed cross sections. Transmission electron microscopy showed a complete disorganization of the axoneme and para-axonemal structures such as the mitochondrial sheath, fibrous sheath, and outer dense fibers. In addition, numerous vesicles that contain unassembled microtubules were observed within developing spermatids. Acrosome structure analysis showed normal appearance, thus excluding a crucial role of IFT81 in acrosome biogenesis. These observations showed that IFT81 is an important member of the IFT process during spermatogenesis and that its absence is associated with abnormal flagellum formation leading to male infertility. The expression levels of several IFT components in testes, including IFT20, IFT25, IFT27, IFT57, IFT74, and IFT88, but not IFT140, were significantly reduced in homozygous mutant mice. Overall, our study demonstrates that IFT81 plays an essential role during spermatogenesis by modulating the assembly and elongation of the sperm flagella.
Asunto(s)
Fertilidad , Flagelos/metabolismo , Infertilidad Masculina/metabolismo , Proteínas Asociadas a Microtúbulos/metabolismo , Proteínas Musculares/metabolismo , Espermatocitos/metabolismo , Espermatogénesis , Testículo/metabolismo , Animales , Proteínas del Citoesqueleto/metabolismo , Epidídimo/metabolismo , Epidídimo/fisiopatología , Epidídimo/ultraestructura , Flagelos/ultraestructura , Infertilidad Masculina/genética , Infertilidad Masculina/patología , Infertilidad Masculina/fisiopatología , Masculino , Ratones Endogámicos C57BL , Ratones Noqueados , Proteínas Asociadas a Microtúbulos/deficiencia , Proteínas Asociadas a Microtúbulos/genética , Proteínas Musculares/deficiencia , Proteínas Musculares/genética , Transducción de Señal , Recuento de Espermatozoides , Motilidad Espermática , Espermatocitos/ultraestructura , Testículo/fisiopatología , Testículo/ultraestructuraRESUMEN
Drosophila spermatocytes have giant centrioles that display unique properties. Both the parent centrioles maintain a distinct cartwheel and nucleate a cilium-like region that persists during the meiotic divisions and organizes a structured sperm axoneme. Moreover, the parent centrioles are morphologically undistinguishable, unlike vertebrate cells in which mother and daughter centrioles have distinct structural features. However, our immunofluorescence analysis of the parent centrioles in mature primary spermatocytes revealed an asymmetric accumulation of the typical Sas4 and Sas6 proteins. Notably, the fluorescence intensity of Sas4 and Sas6 at the daughter centrioles is greater than the intensity found at the mother ones. In contrast, the centrioles of wing imaginal disc cells display an opposite condition in which the loading of Sas4 and Sas6 at the mother centrioles is greater. These data underlie a subtle asymmetry among the parent centrioles and point to a cell type diversity of the localization of the Sas4 and Sas6 proteins.
Asunto(s)
Centriolos/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/citología , Espermatocitos/citología , Espermatocitos/metabolismo , Animales , Centriolos/ultraestructura , Drosophila melanogaster/ultraestructura , Larva/citología , Larva/ultraestructura , Masculino , Meiosis , Proteínas Asociadas a Microtúbulos , Microtúbulos/metabolismo , Espermatocitos/ultraestructuraRESUMEN
A typical nucleolus structure is shaped by three components. A meshwork of fine fibers forming the fibrillar center (FC) is surrounded by densely packed fibers forming the dense fibrillar component (DFC). Meanwhile, wrapping the FC and DFC is the granular component (GC). During the mitotic prophase, the nucleolus undergoes disassembling of its components. On the contrary, throughout the first meiotic prophase that occurs in the cells of the germ line, small nucleoli are assembled into one nucleolus by the end of the prophase. These nucleoli are transcriptionally active, suggesting that they are fully functional. Electron microscopy analysis has suggested that these nucleoli display their three main components but a typical organization has not been observed. Here, by immunolabeling and electron microscopy, we show that the nucleolus has its three main components. The GC is interlaced with the DFC and is not as well defined as previously thought during leptotene and zygotene stage.
Asunto(s)
Nucléolo Celular/ultraestructura , Profase/fisiología , Espermatocitos/citología , Espermatocitos/ultraestructura , Animales , Nucléolo Celular/fisiología , Masculino , Meiosis/fisiología , Microscopía Electrónica , Ratas , Complejo Sinaptonémico/ultraestructura , Testículo/citología , Testículo/ultraestructuraRESUMEN
Telomeres are repeat regions of DNA that cap either end of each chromosome, thereby providing stability and protection from the degradation of gene-rich regions. Each cell replication causes the loss of telomeric repeats due to incomplete DNA replication, though it is well-established that progressive telomere shortening is evaded in male germ cells by the maintenance of active telomerase. However, germ cell telomeres are still susceptible to disruption or insult by oxidative stress, toxicant exposure, and aging. Our aim was to examine the relative telomere length (rTL) in an outbred Sprague Dawley (SD) and an inbred Brown Norway (BN) rat model for paternal aging. No significant differences were found when comparing pachytene spermatocytes (PS), round spermatids (RS), and sperm obtained from the caput and cauda of the epididymis of young and aged SD rats; this is likely due to the high variance observed among individuals. A significant age-dependent decrease in rTL was observed from 115.6 (±6.5) to 93.3 (±6.3) in caput sperm and from 142.4 (±14.6) to 105.3 (±2.5) in cauda sperm from BN rats. Additionally, an increase in rTL during epididymal maturation was observed in both strains, most strikingly from 115.6 (±6.5) to 142 (±14.6) in young BN rats. These results confirm the decrease in rTL in rodents, but only when an inbred strain is used, and represent the first demonstration that rTL changes as sperm transit through the epididymis.
Asunto(s)
Espermatogénesis/genética , Telómero/metabolismo , Envejecimiento/genética , Animales , Masculino , Ratas , Ratas Endogámicas BN , Ratas Sprague-Dawley , Espermátides/ultraestructura , Espermatocitos/ultraestructura , Telómero/genética , Acortamiento del TelómeroRESUMEN
The accuracy of the two sequential meiotic divisions in oocytes is essential for creating a haploid gamete with a normal chromosomal content. Here, we have analysed the 3D dynamics of chromosomes during the second meiotic division in live mouse oocytes. We find that chromosomes form stable kinetochore-microtubule attachments at the end of prometaphase II stage that are retained until anaphase II onset. Remarkably, we observe that more than 20% of the kinetochore-microtubule attachments at the metaphase II stage are merotelic or lateral. However, < 1% of all chromosomes at onset of anaphase II are found to lag at the spindle equator and < 10% of the laggards missegregate and give rise to aneuploid gametes. Our results demonstrate that aberrant kinetochore-microtubule attachments are not corrected at the metaphase stage of the second meiotic division. Thus, the accuracy of the chromosome segregation process in mouse oocytes during meiosis II is ensured by an efficient correction process acting at the anaphase stage.
Asunto(s)
Anafase , Cinetocoros/ultraestructura , Metafase , Microtúbulos/ultraestructura , Oocitos/ultraestructura , Secuencia de Aminoácidos , Animales , Cromátides/metabolismo , Cromátides/ultraestructura , Segregación Cromosómica , Femenino , Humanos , Cinetocoros/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Microtúbulos/metabolismo , Oocitos/metabolismo , Espermatocitos/metabolismo , Espermatocitos/ultraestructura , Huso Acromático/metabolismo , Huso Acromático/ultraestructura , Imagen de Lapso de TiempoRESUMEN
There is increasing evidence that indicates benzo[a]pyrene (B[a]P) and its active metabolite benzo[a]pyrene-7, 8-dihydrodiol-9, 10-epoxide (BPDE) are endocrine disruptors that can cause reproductive toxicity. Nevertheless, the underlying mechanisms are still obscure. The present study investigates the impacts of B[a]P and BPDE on mitochondria, a sensitive target affected by multiple chemicals, in spermatogenic cells. It showed that BPDE treatment induced mitochondrial dysfunction and the inhibition of mitochondrial biogenesis in mouse spermatocyte-derived cells (GC-2). These effects were efficiently mitigated by pretreatment with ZLN005, an activator of PGC-1α, in GC-2 cells. TERT knockdown and re-expression cell models were established to demonstrate that TERT regulated the BPDE-induced mitochondrial damage via PGC-1α signaling in GC-2 cells. Moreover, upregulating or knockdown SIRT1 expression attenuated or aggravated BPDE-induced mitochondrial compromise by activating or inhibiting, respectively, the TERT and PGC-1α molecules in GC-2 cells. Finally, we observed that BPDE markedly elevated oxidative stress in GC-2 cells. Resveratrol and N-acetylcysteine, as reactive oxygen species (ROS) scavengers, attenuated BPDE-mediated mitochondrial damage by increasing SIRT1 activity and expression in GC-2 cells. The in vitro results were corroborated by in vivo experiments in rats treated with B[a]P for 4â¯weeks. B[a]P administration caused mitochondrial damage and mitochondria-dependent apoptosis in spermatogenic cells, as well as the decreased expression of SIRT1, TERT, and PGC-1α. In summary, the results of the present study demonstrate that B[a]P and BPDE induce mitochondrial damage through ROS production that suppresses SIRT1/TERT/PGC-1a signaling and mediate B[a]P- and BPDE-mediated reproductive toxicity.
Asunto(s)
Benzopirenos/toxicidad , Mitocondrias/efectos de los fármacos , Coactivador 1-alfa del Receptor Activado por Proliferadores de Peroxisomas gamma/fisiología , Sirtuina 1/fisiología , Espermatozoides/efectos de los fármacos , Telomerasa/fisiología , 7,8-Dihidro-7,8-dihidroxibenzo(a)pireno 9,10-óxido/toxicidad , Animales , Apoptosis/efectos de los fármacos , Benzo(a)pireno/toxicidad , Línea Celular , ADN Mitocondrial/análisis , Técnicas de Silenciamiento del Gen , Masculino , Ratones , Mitocondrias/fisiología , Coactivador 1-alfa del Receptor Activado por Proliferadores de Peroxisomas gamma/genética , Ratas , Ratas Sprague-Dawley , Especies Reactivas de Oxígeno/metabolismo , Especies Reactivas de Oxígeno/farmacología , Sirtuina 1/genética , Espermatocitos/efectos de los fármacos , Espermatocitos/metabolismo , Espermatocitos/ultraestructura , Espermatozoides/metabolismo , Espermatozoides/ultraestructura , Telomerasa/genética , Testículo/efectos de los fármacosRESUMEN
The histomorphology of the reproductive system and the germ cells has been useful to establish phylogenetic relationships in many insects. However, these elements remain little known in the Curculionidae. In this study, histomorphological structure of the male reproductive system of Tanymecus dilaticollis, which is economically important, is described, illustrated using stereomicroscopy, light microscopy, and scanning electron microscopy techniques, and discussed in relation to other Coleoptera species. Results showed that distinctive features of the male reproductive system of T. dilaticollis consist of a pair of yellowish testes, a pair of seminal vesicles, a pair of vasa deferentia, an ejaculatory duct, accessory glands, prostate glands, and aedeagus. Each testis is subdivided into two testicular follicles, enclosed by a peritoneal sheath. Each follicle of the mature testes is full sperm cysts with germ cells at various stages development of spermatogenesis. The testes have four types of germ cells (spermatogonia, spermatocytes, spermatids, and spermatozoa). They are occupied by the growth zone containing spermatogonia and spermatocytes, the maturation zone containing spermatids, while differentiation zone containing spermatozoa. There is a seminal vesicle at the center of each testis. Most mature sperms are stored in the seminal vesicle. Each testis is attached to the vas deferens by a stalk-like seminal vesicle. In the distal part, vasa deferentia fuse with the ejaculatory duct. It is linked to the aedeagus. The provided results will contribute to the understanding of the reproductive cell biology of Curculionidae.
Asunto(s)
Genitales Masculinos/anatomía & histología , Testículo/anatomía & histología , Gorgojos/anatomía & histología , Animales , Masculino , Microscopía , Microscopía Electrónica de Rastreo , Espermatocitos/ultraestructura , Espermatogonias/ultraestructura , Espermatozoides/citología , Espermatozoides/ultraestructura , Testículo/citologíaRESUMEN
Fine particulate matters (PM2.5) have been associated with male reproductive toxicity because it can penetrate into the lung's gas-exchange region, and spread to the whole body via circulatory system. Previous studies have shown that PM2.5 could induce DNA damage and apoptosis by reactive oxygen species (ROS). The aim of the present study is to determine the exact mechanism and role of apoptosis induced by PM2.5 in spermatocyte cells. Male Sprague-Dawley (SD) rats were treated with normal saline (control group) or PM2.5 with the doses of 1.8, 5.4 and 16.2â¯mg/kg bw. via intratracheal instillation every 3 days for 30 days. Mouse spermatocyte-derived cells (GC-2spd cells) were treated with various concentrations (0, 50, 100, 200⯵g/mL) of PM2.5 for 24â¯h. The results showed that exposure to PM2.5 resulted in injury of testicular tissue and impaired mitochondria integrity in GC-2spd cells. Moreover, PM2.5 induced DNA damage and apoptosis in GC-2spad cells via ROS generation, and the ATM/P53/CDK2 and mitochondria apoptosis pathway autophagy signal pathway were activated. N-Acetyl-L-cysteine (NAC), a well-known antioxidant, ameliorated DNA damage, and inhibited apoptosis. These findings demonstrated PM2.5 might induce apoptosis via the mitochondrial apoptosis pathway through causing DNA damage resulting from oxidative stress, and finally caused spermatogenesis disorder.
Asunto(s)
Apoptosis/efectos de los fármacos , Daño del ADN , Mitocondrias/efectos de los fármacos , Material Particulado/toxicidad , Transducción de Señal/efectos de los fármacos , Espermatocitos/efectos de los fármacos , Acetilcisteína/metabolismo , Animales , Antioxidantes/metabolismo , Proteínas de la Ataxia Telangiectasia Mutada/metabolismo , Línea Celular , Quinasa 2 Dependiente de la Ciclina/metabolismo , Masculino , Ratones , Mitocondrias/metabolismo , Estrés Oxidativo/efectos de los fármacos , Ratas , Ratas Sprague-Dawley , Especies Reactivas de Oxígeno/metabolismo , Espermatocitos/metabolismo , Espermatocitos/ultraestructura , Proteína p53 Supresora de Tumor/metabolismoRESUMEN
A central principle underlying the ubiquity and abundance of pericentromeric satellite DNA repeats in eukaryotes has remained poorly understood. Previously we proposed that the interchromosomal clustering of satellite DNAs into nuclear structures known as chromocenters ensures encapsulation of all chromosomes into a single nucleus (Jagannathan et al., 2018). Chromocenter disruption led to micronuclei formation, resulting in cell death. Here we show that chromocenter formation is mediated by a 'modular' network, where associations between two sequence-specific satellite DNA-binding proteins, D1 and Prod, bound to their cognate satellite DNAs, bring the full complement of chromosomes into the chromocenter. D1 prod double mutants die during embryogenesis, exhibiting enhanced phenotypes associated with chromocenter disruption, revealing the universal importance of satellite DNAs and chromocenters. Taken together, we propose that associations between chromocenter modules, consisting of satellite DNA binding proteins and their cognate satellite DNA, package the Drosophila genome within a single nucleus.
Asunto(s)
Estructuras Cromosómicas , Drosophila melanogaster/genética , Animales , ADN Satélite/genética , Drosophila melanogaster/crecimiento & desarrollo , Genes de Insecto , Genes Letales , Masculino , Mutación , Espermatocitos/ultraestructuraRESUMEN
An ultrastructural study of developing spermatids in sea urchins, Strongylocentrotus intermedius, showed that macroautophagy is involved in formation of residual bodies and removal of excessive cytoplasm by spermatids during spermatogenesis in this species. During late stages of spermatogenesis spermatids sequester excessive cytoplasm into vesicles, surrounded by a double membrane. Subsequently, these vesicles fused to one another into larger vacuoles, up to 1.5 µm in diameter. Finally, the vacuoles transformed into residual bodies by condensing their content into finely granular material of varying electron density, separated from cytoplasm by a single membrane. An immunoelectron microscopic study of late spermatids with the antibodies, raised against microtubule-associated protein 1 A/1B-light chain 3 (LC3), which is a marker of autophagosomes, showed that residual bodies in late spermatids of S. intermedius were LC3-positive.
Asunto(s)
Autofagia/genética , Erizos de Mar/genética , Espermátides/ultraestructura , Espermatogénesis/genética , Animales , Masculino , Microscopía Electrónica , Erizos de Mar/crecimiento & desarrollo , Espermatocitos/ultraestructura , Espermatogonias/ultraestructura , Espermatozoides/ultraestructura , Testículo/ultraestructuraRESUMEN
Heat shock factors (Hsfs) are transcription factors that regulate responses to heat shock and other environmental stimuli. Four heat shock factors (Hsf1-4) have been characterized from vertebrates to date. In addition to stress response, they also play important roles in development and gametogenesis. Here, we study the fifth member of heat shock factor family, Hsf5, using zebrafish as a model organism. Mutant hsf5-/- males, generated by CRISPR/Cas9 technique, were infertile with drastically reduced sperm count, increased sperm head size, and abnormal tail architecture, whereas females remained fertile. We show that Hsf5 is required for progression through meiotic prophase 1 during spermatogenesis as suggested by the accumulation of cells in the leptotene and zygotene-pachytene stages and increased apoptosis in post-meiotic cells. hsf5-/- mutants show gonadal misregulation of a substantial number of genes with roles in cell cycle, apoptosis, protein modifications, and signal transduction, indicating an important role of Hsf5 in early stages of spermatogenesis.
Asunto(s)
Factores de Transcripción del Choque Térmico/metabolismo , Espermatogénesis , Proteínas de Pez Cebra/metabolismo , Pez Cebra/fisiología , Animales , Apoptosis , Femenino , Fertilidad , Factores de Transcripción del Choque Térmico/genética , Masculino , Meiosis , Mutación/genética , Caracteres Sexuales , Espermatocitos/citología , Espermatocitos/metabolismo , Espermatocitos/ultraestructura , Espermatozoides/citología , Espermatozoides/ultraestructura , Testículo/citología , Testículo/ultraestructura , Transcriptoma/genética , Proteínas de Pez Cebra/genéticaRESUMEN
The fruit-fly Drosophila melanogaster harbours different types of ciliary structures: ciliary projections associated with neurons of type I and cilium-like regions (CLRs) found during male gametogenesis. The latter deserve particular attention since they are morphologically similar to vertebrate primary cilia and transform into the sperm axonemes during spermiogenesis. Although, all the centrioles are able to organize the CLRs, we found that the mother centriole docks first to the plasma membrane suggesting a new intrinsic functional asymmetry between the parent centrioles. We also show that the CLRs lack the Y-links that connect the axoneme doublets with the plasma membrane in conventional primary cilia. Moreover, the C-tubules, that are lacking in the axoneme of the primary cilia, persisted along the CLRs albeit modified into longitudinal blades. Remarkably, mutant flies in which the CLRs are devoid of the C-tubules or their number is reduced lack sperm axonemes or have incomplete axonemes. Therefore, the C-tubules are dispensable for the assembly of the CLRs but are essential for sperm axoneme elongation and maintenance in Drosophila.
Asunto(s)
Centriolos/ultraestructura , Cilios/ultraestructura , Drosophila melanogaster/ultraestructura , Pupa/ultraestructura , Espermatocitos/ultraestructura , Espermatogénesis/genética , Animales , Axonema/metabolismo , Axonema/ultraestructura , Proteínas de Ciclo Celular/deficiencia , Proteínas de Ciclo Celular/genética , Membrana Celular/metabolismo , Membrana Celular/ultraestructura , Centriolos/metabolismo , Cilios/metabolismo , Proteínas de Drosophila/deficiencia , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/genética , Drosophila melanogaster/crecimiento & desarrollo , Drosophila melanogaster/metabolismo , Regulación del Desarrollo de la Expresión Génica , Masculino , Meiosis , Microscopía Electrónica de Transmisión , Mutación , Pupa/genética , Pupa/crecimiento & desarrollo , Pupa/metabolismo , Espermatocitos/crecimiento & desarrollo , Espermatocitos/metabolismoRESUMEN
We show that an inhomogeneous Bernoulli site percolation process running upon a fullerene's dual [Formula: see text] can be used for representing bivalents attached to the nuclear envelope in mouse Mus M. Domesticus 2n = 40 meiotic spermatocytes during pachytene. It is shown that the induced clustering generated by overlapping percolation domains correctly reproduces the probability distribution observed in the experiments (data) after fine tuning the parameters.