Perinuclear Ring Research Articles

Therapeutic effects of melatonin in long-term exposure to 2100 MHz radiofrequency radiation on rat sperm characteristics

IntroductionRadiofrequency electromagnetic fields (RF-EMFs) are one of the risk factors for male reproductive health and melatonin can be an ideal candidate for therapeutic development against RF-induced male fertility problems due to its antioxidant properties. The possible therapeutic role of melatonin in the destructive effects of 2100MHz RF radiation on rat sperm characteristics is investigated in the present study. MethodsWistar albino rats were divided into four groups and the experiment continued for ninety consecutive days; Control, Melatonin (10mg/kg, subcutaneously), RF (2100MHz, thirty minutes per day, whole-body), and RF+Melatonin groups. Left caudal epididymis and ductus deferens tissues were placed in sperm wash solution (at 37°C) and dissected. The sperms were counted and stained. Measurements of the perinuclear ring of the manchette and posterior portion of the nucleus (ARC) were performed and the sperms were examined at an ultrastructural level. All of the parameters were evaluated statistically. ResultsThe percentages of abnormal sperm morphology were significantly increased with RF exposure, while the total sperm count was significantly decreased. RF exposure also showed harmful effects on acrosome, axoneme, mitochondrial sheath, and outer dense fibers at the ultrastructural level. The number of total sperms, sperms with normal morphology increased, and ultrastructural appearance returned to normal by melatonin administration. DiscussionThe data showed that melatonin may be a beneficial therapeutic agent for long-term exposure of 2100MHz RF radiation-related reproductive impairments.

Histopathological characterisation of trunk-dominant canine pemphigus foliaceus, and comparison with classic facial and insecticide-triggered forms.

While the clinical features were described recently, the histopathological characterisation of trunk-dominant canine pemphigus foliaceus (PF) is lacking, and whether it differs from classic facial or insecticide-triggered PF is unknown. This study describes the histopathological findings of trunk-dominant PF, and compares the results to classic facial and insecticide-triggered PF. Skin biopsies from 103 dogs with clinically characterised trunk-dominant (n = 33), classic facial (n = 26) and insecticide-triggered PF (n = 44) were included. Histological sections, randomised and blinded, were scored for over 50 morphological parameters of pustules, epidermis, dermis, adnexa and crusts. Intact pustule area and width were measured by digital microscopy. In trunk-dominant PF, 77 intact pustules were predominantly subcorneal (0.0019-1.940 mm2 area, 0.0470-4.2532 mm wide), and contained from one to over 100 acantholytic keratinocytes. Pustules had boat acantholytic cells, corneocytes, perinuclear eosinophilic rings, neutrophil rosettes, acantholytic cell necrosis, rafts, cling-ons and/or eosinophils. Peripustular epidermal spongiosis, necrosis and lymphocyte exocytosis occurred, as did follicular pustules. Mixed dermal inflammation often contained eosinophils. Trunk-dominant PF did not differ from the other PF groups except for few parameters, such as having fewer rafts (p = 0.003). Additional autoimmune inflammatory patterns occurred in all PF groups. Trunk-dominant PF and other canine PF variants are histologically similar, which indicates shared pathomechanisms. The identification of common boat acantholytic cells and corneocyte separation has implications for the mechanisms of acantholysis. The diversity of histopathological and polyautoimmunity features support complicated immune mechanisms. Finally, results indicate that diagnostic biopsies cannot differentiate between these PF variants in dogs.

Crooke's cell pituitary adenoma in a 7‐month‐old dog with Cushing's syndrome

AbstractA 7‐month‐old Boxer puppy was referred for growth retardation. Cushing's syndrome was diagnosed based on clinical signs, physical appearance, elevated urine cortisol/creatinine ratios and unsuppressed plasma cortisol after a low dose of dexamethasone. At the time, there was no evidence of pituitary or adrenal neoplasia on imaging studies. After 60 days of trilostane treatment, the clinical signs of Cushing's syndrome had disappeared. Thirty months later, the dog died of cardiac disease. Pathological examination revealed a pituitary macroadenoma with bilateral adrenocortical hyperplasia. Immunostaining for adrenocorticotropic hormone confirmed a corticotroph adenoma. High Ki‐67 staining denoted the aggressiveness of the tumour. Haematoxylin–eosin, periodic acid‐Schiff and cytokeratin 7 staining revealed a perinuclear hyaline ring in the neoplastic cells, compatible with a Crooke's cell adenoma. This is the first case of Crooke's cell pituitary adenoma causing Cushing's syndrome in a puppy with growth retardation.

Structure and function of the N-terminal extension of the formin INF2

In INF2—a formin linked to inherited renal and neurological disease in humans—the DID is preceded by a short N-terminal extension of unknown structure and function. INF2 activation is achieved by Ca2+-dependent association of calmodulin (CaM). Here, we show that the N-terminal extension of INF2 is organized into two α-helices, the first of which is necessary to maintain the perinuclear F-actin ring and normal cytosolic F-actin content. Biochemical assays indicated that this helix interacts directly with CaM and contains the sole CaM-binding site (CaMBS) detected in INF2. The residues W11, L14 and L18 of INF2, arranged as a 1-4-8 motif, were identified as the most important residues for the binding, W11 being the most critical of the three. This motif is conserved in vertebrate INF2 and in the human population. NMR and biochemical analyses revealed that CaM interacts directly through its C-terminal lobe with the INF2 CaMBS. Unlike control cells, INF2 KO cells lacked the perinuclear F-actin ring, had little cytosolic F-actin content, did not respond to increased Ca2+ concentrations by making more F-actin, and maintained the transcriptional cofactor MRTF predominantly in the cytoplasm. Whereas expression of intact INF2 restored all these defects, INF2 with inactivated CaMBS did not. Our study reveals the structure of the N-terminal extension, its interaction with Ca2+/CaM, and its function in INF2 activation.

Causes and Pathophysiology of Acquired Sideroblastic Anemia.

The sideroblastic anemias are a heterogeneous group of inherited and acquired disorders characterized by anemia and the presence of ring sideroblasts in the bone marrow. Ring sideroblasts are abnormal erythroblasts with iron-loaded mitochondria that are visualized by Prussian blue staining as a perinuclear ring of green-blue granules. The mechanisms that lead to the ring sideroblast formation are heterogeneous, but in all of them, there is an abnormal deposition of iron in the mitochondria of erythroblasts. Congenital sideroblastic anemias include nonsyndromic and syndromic disorders. Acquired sideroblastic anemias include conditions that range from clonal disorders (myeloid neoplasms as myelodysplastic syndromes and myelodysplastic/myeloproliferative neoplasms with ring sideroblasts) to toxic or metabolic reversible sideroblastic anemia. In the last 30 years, due to the advances in genomic techniques, a deep knowledge of the pathophysiological mechanisms has been accomplished and the bases for possible targeted treatments have been established. The distinction between the different forms of sideroblastic anemia is based on the study of the characteristics of the anemia, age of diagnosis, clinical manifestations, and the performance of laboratory analysis involving genetic testing in many cases. This review focuses on the differential diagnosis of acquired disorders associated with ring sideroblasts.

PFN4 is required for manchette development and acrosome biogenesis during mouse spermiogenesis.

ABSTRACTProfilin 4 (Pfn4) is expressed during spermiogenesis and localizes to the acrosome-acroplaxome-manchette complex. Here, we generated PFN4-deficient mice, with sperm displaying severe impairment in manchette formation. Interestingly, HOOK1 staining suggests that the perinuclear ring is established; however, ARL3 staining is disrupted, suggesting that lack of PFN4 does not interfere with the formation of the perinuclear ring and initial localization of HOOK1, but impedes microtubular organization of the manchette. Furthermore, amorphous head shape and flagellar defects were detected, resulting in reduced sperm motility. Disrupted cis- and trans-Golgi networks and aberrant production of proacrosomal vesicles caused impaired acrosome biogenesis. Proteomic analysis showed that the proteins ARF3, SPECC1L and FKBP1, which are involved in Golgi membrane trafficking and PI3K/AKT pathway, are more abundant in Pfn4−/− testes. Levels of PI3K, AKT and mTOR were elevated, whereas AMPK level was reduced, consistent with inhibition of autophagy. This seems to result in blockage of autophagic flux, which could explain the failure in acrosome formation. In vitro fertilization demonstrated that PFN4-deficient sperm is capable of fertilizing zona-free oocytes, suggesting a potential treatment for PFN4-related human infertility.

Combination of Lanosterol and Nilvadipine Nanosuspensions Rescues Lens Opacification in Selenite-Induced Cataractic Rats.

It has recently been reported that lanosterol (LAN) plays a preventive role against lens opacification through the reversal of crystalline aggregation. However, the effect of LAN is not sufficient to restore lens transparency. In this study, we designed ophthalmic nanosuspensions (LAN-ONSs and NIL-ONSs) based on LAN and nilvadipine (NIL), which can counteract cataract-related factors (e.g., enhanced Ca2+ and calpain levels), and investigated whether the combination of LAN-ONSs and NIL-ONSs can restore the nuclear lens opacity in sodium-selenite-induced cataractic rats (cataractic rats). The mean particle sizes of the LAN-ONSs and NIL-ONSs were 108.8 nm and 89.0 nm, respectively. The instillation of the LAN-ONSs or NIL-ONSs successfully delivered the drugs (LAN or NIL) into the lenses of the rats, although the instillation of LAN-ONSs or NIL-ONSs alone did not increase lens transparency in the cataractic rats. On the other hand, the cataract-related factors (enhanced Ca2+ and calpain levels) were significantly alleviated by the combination of LAN-ONSs and NIL-ONSs; furthermore, the perinuclear refractile ring in the lens nucleus and enhanced number of swollen fibers were attenuated by the LAN-ONS and NIL-ONS combination. Moreover, the opacity levels in the cataractic rats were reduced after treatment with the combination of LAN-ONSs and NIL-ONSs. It is possible that the combination of LAN and NIL will be useful for the treatment of lens opacification in the future.

Frequent Spindle Assembly Errors Require Structural Rearrangement to Complete Meiosis in Zea mays.

The success of an organism is contingent upon its ability to faithfully pass on its genetic material. In the meiosis of many species, the process of chromosome segregation requires that bipolar spindles be formed without the aid of dedicated microtubule organizing centers, such as centrosomes. Here, we describe detailed analyses of acentrosomal spindle assembly and disassembly in time-lapse images, from live meiotic cells of Zea mays. Microtubules organized on the nuclear envelope with a perinuclear ring structure until nuclear envelope breakdown, at which point microtubules began bundling into a bipolar form. However, the process and timing of spindle assembly was highly variable, with frequent assembly errors in both meiosis I and II. Approximately 61% of cells formed incorrect spindle morphologies, with the most prevalent being tripolar spindles. The erroneous spindles were actively rearranged to bipolar through a coalescence of poles before proceeding to anaphase. Spindle disassembly occurred as a two-state process with a slow depolymerization, followed by a quick collapse. The results demonstrate that maize meiosis I and II spindle assembly is remarkably fluid in the early assembly stages, but otherwise proceeds through a predictable series of events.

Balbiani body formation and cytoplasmic zonation during early oocyte development in two Clupeiform fishes.

The Balbiani body (Bb) was examined in primary growth phase oocytes for the first time in two clupeoid fish species, the Mediterranean sardine, Sardina pilchardus, and the European anchovy, Engraulis encrasicolus, which belong to different families, Clupeidae and Engraulidae, respectively. Cytoplasmic morphological changes of early secondary growth oocytes were also investigated using confocal laser scanning microscopy, light and transmission electron microscopy. The ultrastructural observations showed that the two species develop a distinct spherical Bb. However, differences in the cytoplasm, mainly in the perinuclear area, were observed. Briefly, in sardine the Bb coexists with a thick perinuclear ring containing mitochondria, nuage, endoplasmic reticulum and small vesicles, while in anchovy this perinuclear ring is thinner, consisting of complexes of nuage and mitochondria. After the disassembly of the Bb, a prominent cytoplasmic zonation develops in the secondary growth oocytes of sardine and anchovy, although with different organelle distribution between the two species. Sardine oocytes exhibit a thick zone of endoplasmic reticulum around the nucleus, whereas in those of anchovy, a thick mitochondria-rich ring surrounding the nucleus was observed. The cytoplasmic characteristics, such as the perinuclear ring in primary oocytes in sardine and the mitochondria-rich ring of early secondary oocytes in anchovy, are also discernible in histological sections by standard procedures and could thus be used as indicators of maturity or imminent spawning period in routine light microscopy observations, providing a valuable tool for applied fisheries biology.

The testis-specific LINC component SUN3 is essential for sperm head shaping during mouse spermiogenesis

Sperm head shaping is a key event in spermiogenesis and is tightly controlled via the acrosome-manchette network. Linker of nucleoskeleton and cytoskeleton (LINC) complexes consist of Sad1 and UNC84 domain-containing (SUN) and Klarsicht/ANC-1/Syne-1 homology (KASH) domain proteins and form conserved nuclear envelope bridges implicated in transducing mechanical forces from the manchette to sculpt sperm nuclei into a hook-like shape. However, the role of LINC complexes in sperm head shaping is still poorly understood. Here we assessed the role of SUN3, a testis-specific LINC component harboring a conserved SUN domain, in spermiogenesis. We show that CRISPR/Cas9-generated Sun3 knockout male mice are infertile, displaying drastically reduced sperm counts and a globozoospermia-like phenotype, including a missing, mislocalized, or fragmented acrosome, as well as multiple defects in sperm flagella. Further examination revealed that the sperm head abnormalities are apparent at step 9 and that the sperm nuclei fail to elongate because of the absence of manchette microtubules and perinuclear rings. These observations indicate that Sun3 deletion likely impairs the ability of the LINC complex to transduce the cytoskeletal force to the nuclear envelope, required for sperm head elongation. We also found that SUN3 interacts with SUN4 in mouse testes and that the level of SUN4 proteins is drastically reduced in Sun3-null mice. Altogether, our results indicate that SUN3 is essential for sperm head shaping and male fertility, providing molecular clues regarding the underlying pathology of the globozoospermia-like phenotype.

The possible protective effects of curcumin in the case of benzo(a)pyrene administration on rat sperm motility and morphology

Background: In this study, our aim is to investigate the possible protective effects of curcumin on potential damage caused by benzo(a)pyrene (BaP) on rat sperm motility and morphology. Methods: 36 Wistar Albino male rats were divided into six groups: Group 1, Control; Group 2, Corn oil (BaP dissolver); Group 3, DMSO (Curcumin dissolver); Group 4, BaP; Group 5, Curcumin; Group 6, BaP+Curcumin. By the end of the six week oral administration period, left caudal epididymis and ductus deferens tissues were placed in Pure Sperm Wash (Nidacon) solution (at 37°C) and dissected. Sperms were counted and stained. Measurements of the perinuclear ring of the manchette and the posterior portion of the nucleus were performed. All of the parameters were evaluated statistically. Results: BaP administration caused a decrease in the number of total sperms and total motile sperms, while increasing abnormalities in tail, acrosome and cytoplasmic droplet particularly. Abnormalities did not approach the control group by curcumin administration in expected rates, but the percentage reduced. The number of total and motile sperms increased by curcumin. All parameters were statistically supported. Conclusions: In conclusion, curcumin is one of the antioxidant that could be used potentially to inhibit the effects of Benzo(a)pyrene, but is ineffective in preventing all abnormalities.

The elusive actin cytoskeleton of a green alga expressing both conventional and divergent actins.

The green alga Chlamydomonas reinhardtii is a leading model system to study photosynthesis, cilia, and the generation of biological products. The cytoskeleton plays important roles in all of these cellular processes, but to date, the filamentous actin network within Chlamydomonas has remained elusive. By optimizing labeling conditions, we can now visualize distinct linear actin filaments at the posterior of the nucleus in both live and fixed vegetative cells. Using in situ cryo-electron tomography, we confirmed this localization by directly imaging actin filaments within the native cellular environment. The fluorescently labeled structures are sensitive to the depolymerizing agent latrunculin B (Lat B), demonstrating the specificity of our optimized labeling method. Interestingly, Lat B treatment resulted in the formation of a transient ring-like filamentous actin structure around the nucleus. The assembly of this perinuclear ring is dependent upon a second actin isoform, NAP1, which is strongly up-regulated upon Lat B treatment and is insensitive to Lat B–induced depolymerization. Our study combines orthogonal strategies to provide the first detailed visual characterization of filamentous actins in Chlamydomonas, allowing insights into the coordinated functions of two actin isoforms expressed within the same cell.

Evaluation of Changes in Actin Filaments of RK13 Cells Infected with <i>Malassezia pachydermatis</i>

Background: Malassezia pachydermatis is the main causative agent of canine otitis and also of a myriad of dermatological problems in companion animals; its interaction mechanisms with host cells are still unclear. Objectives: To establish an in vitro infection model of M. pachydermatis-exposed RK13 cells in order to evaluate cell morphological changes as well as changes in the structure of actin filaments. Methods: Cultures of RK13 cells were infected with M. pachydermatis, alterations caused by the yeast were evaluated by optical and fluorescence microscopy. Results: M. pachydermatis adheres itself to the cell and produces the formation of multiple agglomerates that cause changes in cell morphology, formation of cell aggregates in overlays, presence of syncytia and destruction of cell culture structure. The damaged cells presented changes in the actin filaments consisting of thickening of the cell cortex and loss of stress fibers. On the other hand, the formation of perinuclear actin rings in the yeasts was observed. Conclusions: An in vitro infection model was established with M. pachydermatis and alterations in cell morphology were observed consisting of changes in the structure of the actin filaments, overgrowth of the cells and the presence of syncytia.

1α,25 dihydroxi-vitamin D3 modulates CDK4 and CDK6 expression and localization

We recently reported that the vitamin D receptor (VDR) and p38 MAPK participate in pro-differentiation events triggered by 1α,25(OH)2-vitamin D3 [1,25D] in skeletal muscle cells. Specifically, our studies demonstrated that 1,25D promotes G0/G1 arrest of cells inducing cyclin D3 and cyclin dependent kinases inhibitors (CKIs) p21Waf1/Cip1 and p27Kip1 expression in a VDR and p38 MAPK dependent manner. In this work we present data indicating that cyclin-dependent kinases (CDKs) 4 and 6 also play a role in the mechanism by which 1,25D stimulates myogenesis. To investigate VDR involvement in hormone regulation of CDKs 4 and 6, we significantly reduced its expression by the use of a shRNA against mouse VDR, generating the skeletal muscle cell line C2C12-VDR. Investigation of changes in cellular cycle regulating proteins by immunoblotting showed that the VDR is involved in the 1,25D –induced CDKs 4 and 6 protein levels at 6 h of hormone treatment. CDK4 levels remains high during S phase peak and G0/G1 arrest while CDK6 expression decreases at 12 h and increases again al 24 h. The up-regulation of CDKs 4 and 6 by 1,25D (6 h) was abolished in C2C12 cells pre-treated with the ERK1/2 inhibitor, UO126. Moreover, CDKs 4 and 6 expression induced by the hormone nor was detected when α and β isoforms of p38 MAPK were inhibited by compound SB203580. Confocal images show that there is not co-localization between VDR and CDKs at 6 h of hormone treatment, however CDK4 and VDR co-localizates in nucleus after 12 h of 1,25D exposure. Of relevance, at this time 1,25D promotes CDK6 localization in a peri-nuclear ring. Our data demonstrate that the VDR, ERK1/2 and p38 MAPK are involved in the control of CDKs 4 and 6 by 1,25D in skeletal muscle cells sustaining the operation of a VDR and MAPKs –dependent mechanism in hormone modulation of myogenesis.

Alterations in the Nuclear Architecture Produced by the Overexpression of Tau Protein in Neuroblastoma Cells

Abnormal intracellular aggregation of tau protein is a pathological condition leading to neuronal death in Alzheimer's disease. Fibrillar and nonfibrillar aggregates of tau protein alter the normal functioning of neurons by disturbing important cellular processes and distinct membranous organelles. However, tau-caused alterations in the nuclear compartment are not totally established so far. In our study we evaluated whether tau protein and its Asp421-truncated variant produce alterations in the normal architecture of the nucleus when expressed in cultured neuroblastoma cells. After 48 hours of transfection, significant deformity of the nuclear compartment with extensive lobulations along the nuclear envelope was observed in SH-SY5Y cells expressing either full-length tau or Asp421-truncated tau. This aberrant formation did not involve either nuclear fragmentation or cell death. The lobulated nuclei were devoid of tau protein, which mostly remained in the cytoplasm in a nonfibrillar state. Degradation of nuclear Lamins was not observed in tau-expressing SH-SY5Y cells, and a cell-cycle analysis did not show aberrant chromosome accumulation. Thus multiple division defects leading to multinucleation were discarded. The lobulated nuclei in tau-expressing SH-SY5Y cells seem to more resemble the multilobular phenotype of the nuclear envelope seen in Lamin-mutated cells from those pathological conditions leading to premature aging. Nevertheless, in our tau-expressing cells, the abnormal formation of cortical and perinuclear rings of tubulin generated by tau binding may be a more feasible mechanism of a nuclear-cytoskeleton generating force that causes the nuclear deformation.

ADP-ribose polymer depletion leads to nuclear Ctcf re-localization and chromatin rearrangement

Ctcf (CCCTC-binding factor) directly induces Parp [poly(ADP-ribose) polymerase] 1 activity and its PARylation [poly(ADPribosyl)ation] in the absence of DNA damage. Ctcf, in turn, is a substrate for this post-synthetic modification and as such it is covalently and non-covalently modified by PARs (ADP-ribose polymers). Moreover, PARylation is able to protect certain DNA regions bound by Ctcf from DNA methylation. We recently reported that de novo methylation of Ctcf target sequences due to overexpression of Parg [poly(ADP-ribose)glycohydrolase] induces loss of Ctcf binding. Considering this, we investigate to what extent PARP activity is able to affect nuclear distribution of Ctcf in the present study. Notably, Ctcf lost its diffuse nuclear localization following PAR (ADP-ribose polymer) depletion and accumulated at the periphery of the nucleus where it was linked with nuclear pore complex proteins remaining external to the perinuclear Lamin B1 ring. We demonstrated that PAR depletion-dependent perinuclear localization of Ctcf was due to its blockage from entering the nucleus. Besides Ctcf nuclear delocalization, the outcome of PAR depletion led to changes in chromatin architecture. Immunofluorescence analyses indicated DNA redistribution, a generalized genomic hypermethylation and an increase of inactive compared with active chromatin marks in Parg-overexpressing or Ctcf-silenced cells. Together these results underline the importance of the cross-talk between Parp1 and Ctcf in the maintenance of nuclear organization.

A new F-actin structure in fungi: actin ring formation around the cell nucleus ofCryptococcus neoformans

The F-actin cytoskeleton of Cryptococcus neoformans is known to comprise actin cables, cortical patches and cytokinetic ring. Here, we describe a new F-actin structure in fungi, a perinuclear F-actin collar ring around the cell nucleus, by fluorescent microscopic imaging of rhodamine phalloidin-stained F-actin. Perinuclear F-actin rings form in Cryptococcus neoformans treated with the microtubule inhibitor Nocodazole or with the drug solvent dimethyl sulfoxide (DMSO) or grown in yeast extract peptone dextrose (YEPD) medium, but they are absent in cells treated with Latrunculin A. Perinuclear F-actin rings may function as 'funicular cabin' for the cell nucleus, and actin cables as intracellular 'funicular' suspending nucleus in the central position in the cell and moving nucleus along the polarity axis along actin cables.

Ultrastructural Evidence of Oogenesis of the Rusty Parrotfish, Scarus ferrugineus (Teleostei: Scaridae)

Ultrastructural study of oogenesis of the Scarus ferrugineus was carried out during the period of oocyte growth, particularly the changes in nuclear morphology, cytoplasmic organelles, and wall formation. Materials produced in the nucleus and transported to the cytoplasm known as nuage were observed in the oogonia and primary oocytes at premeiotic and perinucleolar stages. This material gives rise to germ plasma in the growing oocytes. In the perinucleolar oocyte, the cytoplasm appears loaded with free ribosomes and dense bodies. Short strands of endoplasmic reticulum (ER), perinuclear mitochondrial ring, and a simple layer of flattened granulosa cells were also detected. Protrusion of short buds from oocyte and granulose surfaces to the perioocyte space was clearly detected in the oocyte. From the early vitellogenic stage (yolk vesicle oocyte) the vitelline envelope was observed as a single electron-dense mesh pattern layer, becoming thicker during the vitellogenic stage. The granulosa cells (GCs) become organelle-rich with elongate mitochondria, free ribosomes, dilated tubular RER, and a Golgi system. Both GCs and thecal cells (TCs) show ultrastructural steroidogenic features, suggesting their primary roles in the production and secretion of steroid hormones at this stage of ovarian development. Remarkable ultrastructural changes were shown in vitellogenic oocytes including increase in RER, proliferation of mitochondria, and protrusion of long microvilli from oocyte and granulosa cells into pore canals of the vitelline membrane. The microvilli withdraw by the end of yolk deposition and the granulosa cells dissociate in fully grown oocytes. In atretic oocytes, the vitelline membrane homogenized and fragmented. Also, GCs, and maybe TCs, proliferated, hypertrophied, and phagocytosed the oocyte remnants forming temporary structure. Degeneration of previtellogenic oocytes prior to sex change was described and discussed.

Actin ring formation around the cell nucleus of long-neck yeast

The unique long-neck yeast Fellomyces fuzhouensis has F-actin cables and cortical patches. Here, we describe a new F-actin structure present in fungi, a perinuclear F-actin collar ring around the cell nucleus. This F-actin structure can be visualized by fluorescent microscopic imaging of rhodamine-phalloidin-stained F-actin in cells treated with the mitotic drug isopropyl N-(3-chlorophenyl) carbamate or the microtubule inhibitor thiabendazol or when cells were grown in cut dried radish medium or yeast extract pepton dextrose (YEPD) medium. In contrast, these structures were absent in cells treated with Latrunculin A. The hypothetical functions of the F-actin ring are discussed.

The role of chromatoid bodies and cytoskeleton in differentiation of rat spermatozoids

The ultrastructural and immunocytochemical study of rat male germ cells on different developing stages has been made. The investigation of morphological changes of spermatogenic cells has demonstrated the presence of tight connections between chromatoid bodies (CBs) and other cell organelles, particularly with the nucleus and Golgi apparatus; has revealed the association of manchette noncentrosomal microtubules (MT) with spermatid perinuclear ring plasma membrane (PM) in the zone of the adhesion intercellular contact--zonula adhaerens (ZA). The comparison of the results obtained in this work with available literary data has given possibility to analyze expected pathways of noncentrosomal MT nucleation in the late spermatids. This paper puts the supposition that noncentrosomal MTs are nucleated on the sites of perinuclear ring ZA. The immunocytochemical analysis discovered two novel proteins for these cells--BASP1 and MARCKS. It has been shown that these proteins present in the CBs in the early spermatids. During the spermatozoid differentiation these proteins are revealed along the outer dense fibers (ODFs) of the sperm tail. BASP1 and MARCKS are supposed to involve in the processes of calcium accumulation in the CBs and ODFs. Calcium ions seem to play the significant role in RNA processing and protein synthesis in spermatids. Calcium is also necessary for the mobility of sperms which is mainly determined by ODFs.