Fibrillar Material Research Articles

Function of atypical mammalian oocyte/zygote nucleoli and its implications for reproductive biology and medicine.

Mammalian oocytes/zygotes contain atypical nucleoli that are composed exclusively of a dense fibrillar material. It has been commonly accepted that these nucleoli serve as a repository of components that are used later on, as the embryo develops, for the construction of typical tripartite nucleoli. Indeed, when nucleoli were removed from immature oocytes (enucleolation) and these oocytes were then matured, fertilized or parthenogenetically activated, development of the produced embryos ceased after one or two cleavages with no detectable nucleoli in nuclei. This indicated that zygotic nucleoli originate exclusively from oocytes, i.e. are maternally inherited. Recently published results, however, do not support this developmental biology dogma and demonstrate that maternal nucleoli in one-cell stage embryos are necessary only during a very short time period after fertilization when they serve as a major heterochromatin organizing structures. Nevertheless, it still remains to be determined, which other functions/roles the atypical oocyte/zygote nucleoli eventually have.

Intraoperative and postoperative complications of cataract surgery in eyes with pseudoexfoliation - An 8-year analysis.

INTRODUCTION:Pseudoexfoliation (PXM) is a fibrillar material deposited in the anterior chamber of the eye and can cause disintegration of zonules and make pupillary dilatation difficult. This can make surgery difficult and result in intraoperative and postoperative complications. The aim of this study was to learn about whether the presence of pseudoexfoliation caused significant complications during cataract surgery.MATERIALS AND METHODS:We did a secondary data analysis of 12,992 eyes from 2007 to 2014 using the National Eye Database of Melaka Hospital Malaysia on intraoperative and postoperative cataract surgery complications of patients with PXM.RESULTS:Patients with PXM were 2.68 times more likely to get intraoperative complications (P < 0.001). They had a higher incidence of lens subluxation, zonular dehiscence, and vitreous loss (P < 0.001). Although posterior capsule rupture (PCR) was the most common intraoperative complication during cataract surgery (4.8%), the presence of pseudoexfoliation was not associated with PCR (P > 0.05). We did not observe any association between patients with pseudoexfoliation and any of the postoperative complications such as corneal decompensation, raised intraocular pressure, and intraocular lens decentration (P > 0.05). Pseudoexfoliation did not cause corneal decompensation (P > 0.05) although corneal decompensation was the highest postoperative complication of cataract surgeries (0.18%).CONCLUSIONS:Patients with PXM had a higher rate of intraoperative complications which were mainly vitreous loss and zonular dehiscence and also lens subluxation/dislocation. We observed poorer visual outcomes in those with PXM following cataract surgery. Patients with pseudoexfoliation should be identified and precautions taken to minimize these complications to get better visual outcomes.

A C-type lectin from Bothrops leucurus snake venom forms amyloid-like aggregates in RPMI medium and are efficiently phagocytosed by peritoneal macrophages

Lectins are carbohydrate-binding proteins that play important roles in the immune system. Under specific conditions, lectins can form amyloids, proteinaceous aggregates rich in cross β-strand structures. A Ca++-dependent lectin, isolated from Bothrops leucurus snake venom (BLL) has demonstrated relevant biological activities such as antibacterial and antitumor activity. In this work, we aimed to study the interaction of BLL with macrophages. The formation of amyloid structures by BLL in a cell culture medium, the effects of the lectin on macrophage morphology and cytokine production were investigated. BLL amyloid-like fibrils in RMPI medium, pH 7.2, at 37 °C was confirmed by binding of Congo Red, Thioflavin T and electron microscopy. Neither binding of amyloid markers nor fibrillar structures were found when the lectin was incubated in RPMI plus galactose, the specific BLL-binding carbohydrate. Several phagocytic compartments containing fibrillar structures were observed in BLL-treated macrophages in RPMI medium for 24 h; these compartments showed an apple-green birefringence after Congo Red staining and were positive for thioflavin S and anti-amyloid antibody, indicating the presence of amyloid-like fibrils. No fibrillar material and no labeling were observed when the macrophages were treated with BLL plus galactose or cytochalasin B, an inhibitor of phagocytosis. BLL did not affect the viability of the cells. A significant release of proinflammatory (TNF-α, IL-6, INF-ϒ and IL-1β) and regulatory (IL-10) cytokines was observed in BLL-treated macrophages. Taken together, our results shed light on the structural organization of BLL, improving knowledge about the interaction of lectin with macrophages. The phagocytosis of amyloid-like aggregates together with the proinflammatory response induced by BLL may open new perspectives for the use of this lectin as an interesting model to study cytokines and the production of other mediators as well as understand the mechanisms occurring in human immune cells during amyloid protein deposition.

Nucleoli in embryos: a central structural platform for embryonic chromatin remodeling?

Nucleoli are the site of ribosomal RNA production and subunit assembly. In contrast to active nucleoli in somatic cells, where three basic sub-compartments can be observed, mammalian oocytes and early embryos contain atypical nucleoli termed "nucleolus-like bodies" or "nucleolus precursor bodies", respectively. Unlike their somatic counterparts, these structures are composed of dense homogenous fibrillar material and exhibit no polymerase activity. Irrespective of these unusual properties, they have been shown to be absolutely essential for embryonic development, as their microsurgical removal results in developmental arrest. Historically, nucleolus-like and nucleolus precursor bodies have been perceived as passive storage sites of nucleolar material, which is gradually utilized by embryos to construct fully functional nucleoli once they have activated their genome and have started to produce ribosomes. For decades, researchers have been trying to elucidate the composition of these organelles and provide the evidence for their repository role. However, only recently has it become clear that the function of these atypical nucleoli is altogether different, and rather than being involved in ribosome biogenesis, they participate in parental chromatin remodeling, and strikingly, the artificial introduction of a single NPB component is sufficient to rescue the developmental arrest elicited by the NPB removal. In this review, we will describe and summarize the experiments that led to the change in our understanding of these unique structures.

Transgenic lysyl oxidase homolog 1 overexpression in the mouse eye results in the formation and release of protein aggregates

Sequence variants in LOXL1 coding for the secreted enzyme lysyl oxidase homolog 1 (LOXL1) associate with pseudoexfoliation (PEX) syndrome, a condition that is characterized by the deposition of extracellular fibrillar PEX material in the anterior eye and other parts of the body. Since the specific role of LOXL1 in the pathogenesis of PEX is unclear, and an increase in its expression was reported for early stages of PEX syndrome, we generated and studied transgenic mice with ocular overexpression of its mouse ortholog Loxl1. The chicken βB1-crystallin promoter was used to overexpress Loxl1 in the lenses of βB1-crystallin-Loxl1 transgenic mice. Transgenic lenses contained high levels of the protein LOXL1 and its mRNA, which were both not detectable in lenses of wildtype littermates. In wildtype mice, immunoreactivity for LOXL1 was mainly seen extracellularly in region of the ciliary zonules. βB1-crystallin-Loxl1 littermates showed an additional diffuse immunostaining in lens fibers and capsule, and in the inner limiting membrane and retina indicating secretion of soluble LOXL1 from transgenic lenses. In addition, lens fibers of transgenic animals contained multiple distinct spots of very intense LOXL1 immunoreactivity. By transmission electron microscopy, those spots correlated with electron-dense round or oval bodies of 20–50 nm in diameter which were localized in the rough endoplasmic reticulum and not seen in wildtype lenses. Immunogold electron microscopy confirmed that the electron-dense bodies contained LOXL1 indicating aggregation of insoluble LOXL1. Similar structures were seen in the extracellular lens capsule suggesting their secretion from lens fibers. Otherwise, no changes were seen between the eyes of βB1-crystallin-Loxl1 mice and their wildtype littermates, neither by light microscopy and funduscopy of whole eyes, nor by scanning and quantitative transmission electron microscopy of ciliary epithelium and zonules. At one month of age, intraocular pressure was significantly higher in transgenic mice than in wildtype littermates. No differences in IOP were seen though at 2–5 months of age. We conclude that LOXL1 has a strong tendency to aggregate in the rER when expressed in vivo at high amounts. A similar scenario, involving intracellular aggregation of LOXL1 and secretion of LOXL1 aggregates into the extracellular space, may be involved in the early pathogenetic events in eyes of PEX patients.

Effect of Magnetic Field on the Fiber Orientation during the Filling Process in Injection Molding, Part 2: Experiments and Electrical Conductivity Measurements

Conductive polymer composite material has been widely used in many industrial fields. Regarding fibrillar composite material, since the fiber’s orientation and distribution affect the properties of product, how the orientation and distribution are controlled is an important key to improve its properties. In this study, the external magnetic field was applied to injection molding for controlling the orientated behavior of magnetic fiber during the filling process. In addition, the fiber orientation and through-plane conductivity was investigated by means of different injection speeds with or without external magnetic field. The influence of magnetic field on the orientation of fiber was observed using the scanning electron microscope. Results from this paper are expected to provide the important references for future study of conductive polymer composite material by using magnetic-assisted injection molding.

Fabrication and Thermal Insulation Properties of Bamboo-Shaped Polymer Fibers by Selective Solvent Vapor Annealing.

Fibrillar materials have gained much attention recently because of their unique properties and potential applications. Although many methods have been developed to fabricate materials, it remains challenging to prepare fibrillar materials containing multicomponent materials or even with complex structures. Here, a facile strategy is developed to fabricate bamboo-shaped fibers by treating electrospun polymer core-shell fibers with solvent vapor annealing. Electrospun polystyrene (PS)/poly(methyl methacrylate) (PMMA) core-shell fibers are first prepared by electrospinning PS/PMMA blend solutions via a phase separation process. When the PS/PMMA core-shell fibers are annealed with the vapor of cyclohexane, which swells and delocalizes the PS domains selectively, the fibers transform into bamboo-shaped structures. The bamboo-shaped structures can be further examined by swelling and delocalizing the PMMA domains selectively, revealing the undulated PS structures. The thermal insulation properties of the fibers with bamboo-shaped structures are observed to be enhanced compared with the original polymer core-shell fibers.

Transmission electron microscopy study of undescribed material at the anterior lens capsule in exfoliation syndrome.

In the present study, we aimed to examine the anterior lens capsule using transmission electron microscopy (TEM) and compare the findings in patients with and without exfoliation syndrome (XFS). Eighteen patients with senile cataract, including 10 with XFS, were included. Anterior capsule specimens were obtained from patients during phacoemulsification through continuous curvilinear capsulorrhexis, and were examined via TEM. In the XFS group, in addition to the typical fibrillar material above the basement membrane of the lens capsule, another unknown, microgranular, electron-dense, unbound material was observed beneath the lens epithelium. Larger formations appeared to detach from the surface of the epithelial cells, and oval or crescent-shaped structures of an electron-denser material were less commonly observed on the apical side of the epithelium. Membranous structures were occasionally attached to epithelial cells that often exhibited thicker or ruptured cell membranes on their apical-free side, along with deposits of electron-dense material. Degenerative lesions of various severities were observed at the epithelium in both groups. The anterior lens capsule epithelium in patients with XFS exhibits a highly irregular and rough margin on its free side, with unbound material over its membrane, which probably contributes to loose contact with the underlying lens and leads to different clinical behaviors in XFS eyes during cataract surgery.

Extracellular Matrix Regulation and Dysregulation in Exfoliation Syndrome.

Several lines of evidence, such as ultrastructural signs for activated fibrillogenesis and excessive production of elastic microfibrillar components in the anterior segment of the eye and throughout the body, indicate that exfoliation syndrome (XFS) is an elastic microfibrillopathy, leading to the accumulation of an abnormal extracellular fibrillar material (XFM). The upregulation of elastic microfibrillar components is paralleled by the selective upregulation of the cross-linking enzyme lysyl oxidase-like 1 (LOXL1) in the early phase of the disease, suggesting that LOXL1 participates in the stabilization of newly synthesized elastic proteins and finally in the stable accumulation of XFM. Whereas the excessive production of elastic proteins rises from early to late XFS stages, possibly mediated by increasing fibrogenic stimuli in the aqueous humor, LOXL1 is downregulated in late stages of the disease by as yet unknown mechanisms, possibly leading to the well-documented elastotic matrix alterations characteristic of eyes with late stage XFS. Several studies indicate complex changes of the proteolytic balance in the anterior segment of XFS eyes, characterized primarily by decreased matrix metalloproteinase-2 activity, the major aqueous matrix metalloproteinase, potentially leading to a shift from appropriate matrix turnover to progressive matrix accumulation. In contrast, in nearly all tissues of the posterior segment, XFM seems to be absent and differential gene expression is confined to the lamina cribrosa, characterized by a stage-independent, primary, and XFS-specific downregulation of LOXL1 and elastic components in XFS eyes. Concomitant with this deficiency, the laminar elastic fiber network displays prominent ultrastructural alterations, which may lead to increased vulnerability to glaucomatous damage. Various growth factors, stress conditions, or dietary factors have been supposed to potentially influence the manifestation of the disease. However, in spite of increasing knowledge, the pathogenetic factors initiating the abnormal matrix process still remain elusive. Such information would be critical for our understanding of disease progression and would disclose new options for pharmaceutical intervention at the onset of the disease.

Exfoliation Syndrome: A Disease of Autophagy and LOXL1 Proteopathy.

Exfoliation syndrome (XFS) is an age-related disease involving the deposition of aggregated fibrillar material (exfoliation material) at extracellular matrices in tissues that synthesize elastic fibers. Its main morbidity is in the eye, where exfoliation material accumulations form on the surface of the ciliary body, iris, and lens. Exfoliation glaucoma (XFG) occurs in a high proportion of persons with XFS and can be a rapidly progressing disease. Worldwide, XFG accounts for about 25% of open-angle glaucoma cases. XFS and XFG show a sharp age-dependence, similarly to the many age-related diseases classified as aggregopathies. Progress in understanding the cellular bases for XFS/XFG has been slowed by a lack of experimental models. Working with primary human tenon fibroblasts (TF) derived from trabeculectomies of XFG patients and age-matched primary open-glaucoma controls, we found that TF from XFG cells display many of the functional features observed in cells from other protein aggregate diseases, such as Parkinson, Alzheimer, Huntington, and age-related macular degeneration. We have documented defects in lysosomal positioning, microtubule organization, autophagy processing rate, and mitochondrial health. In regard to failure of lysosomal and autophagosome positioning in XFG cells, we have found that XFG TF are unable to establish the transnuclear microtubule organizing center that is required for efficient centripetal vesicular locomotion along microtubules. In regard to potential sources of the autophagy malfunction, we have directed our attention to a potential role of the lysyl oxidase-like 1 protein (LOXL1), the elastic fiber catalyst that displays variant-dependent association with risk for XFG. Our experiments show that (a) in XFG cells, a substantial fraction of LOXL1 is processed for degradation by the autophagic system; (b) most of the LOXL1 N-terminus domain exists in a highly disordered state, a condition known to greatly increase the frequency of polypeptide misfolding; (c) that maximum misfolding occurs at amino acid position 153, the location of the high risk variant G153D; and (d) that replacement of glycine (G) by aspartate (D) there results in a substantial decrease in disorder within the 20 amino acid surrounding domain. Finally, we show that clusterin, a protein that can be induced by the presence of intracellular, or extracellular aggregates, is uniformly overexpressed in XFG TF. The implications of our results for a theory relating XFG to cellular aggregopathy are discussed.

Structural associations between organelle membranes in nectary parenchyma cells.

The close association between membranes and organelles, and the intense chloroplast remodeling in parenchyma cells of extrafloral nectaries occurred only at the secretion time and suggest a relationship with the nectar secretion. Associations between membranes and organelles have been well documented in different tissues and cells of plants, but poorly explored in secretory cells. Here, we described the close physical juxtaposition between membranes and organelles, mainly with chloroplasts, in parenchyma cells of Citharexylum myrianthum (Verbenaeceae) extrafloral nectaries under transmission electron microscopy, using conventional and microwave fixation. At the time of nectar secretion, nectary parenchyma cells exhibit a multitude of different organelle and membrane associations as mitochondria-mitochondria, mitochondria-endoplasmic reticulum, mitochondria-chloroplast, chloroplast-nuclear envelope, mitochondria-nuclear envelope, chloroplast-plasmalemma, chloroplast-chloroplast, chloroplast-tonoplast, chloroplast-peroxisome, and mitochondria-peroxisome. These associations were visualized as amorphous electron-dense material, a network of dense fibrillar material and/or dense bridges. Chloroplasts exhibited protrusions variable in shape and extension, which bring them closer to each other and to plasmalemma, tonoplast, and nuclear envelope. Parenchyma cells in the pre- and post-secretory stages did not exhibit any association or juxtaposition of membranes and organelles, and chloroplast protrusions were absent. Chloroplasts had peripheral reticulum that was more developed in the secretory stage. We propose that such subcellular phenomena during the time of nectar secretion optimize the movement of signaling molecules and the exchange of metabolites. Our results open new avenues on the potential mechanisms of organelle contact in parenchyma nectary cells, and reveal new attributes of the secretory cells on the subcellular level.

Effects of nerve stimulation on amphibian oviductal activity

The present study describes, for the first time in an anuran amphibian, the nerve stimulation effects on the secretory and motor activity of the oviduct of adult females. The results reveal that in Rhinella arenarum oviducts, the epithelial and glandular secretory cells of the mucosa of the pars convoluta respond to nerve stimulation secreting the products synthetized and stored in their cytoplasm. The ultrastructural analysis showed that the cell content released is made up of granular, fibrillar and floccular material, exocytosis being the main secretory mechanism found in epithelial secretory cells, although apocrine and holocrine processes could also be observed. In contrast, in glandular cells only exocytosis processes were found. With respect to the participation of the nervous system in the motility of the duct, observations under our experimental conditions indicated that oviductal nerve stimulation promotes motor activity as manifested by a succession of coordinated contractions and relaxations that generate movements similar to peristaltic waves. These results were observed in oviducts from animals captured during the reproductive and post reproductive periods. However, it is important to note that both the secretory response and duct motility are markedly decreased during the post reproductive period of the species.

Effect of mercury on pollen germination and tube growth in Lilium longiflorum.

Pollen development and germination were adversely affected by the presence of mercury, whereas low-concentrations stimulated the whole procedure. Mercury caused morphological anomalies during the tube growth, characterized by irregularly increasing diameters and swelling tips. The main effect was the anomalous cell wall formation at the tip where a substantial number of organelles were found reducing the secretory vesicles. The dense organelle concentration caused a significant reduction of cytoplasmic movement integrity, and the cytosol streaming was gradually reduced or stopped completely. Electron dense, multilamellar myelin-like structures (MMS) of membranous material were frequently present, in close contact with plasmalemma or away from it. A loose network of fibrillar material and spherical aggregates mostly at the tip region were observed which progressively were loosened into the surrounding medium. Elevated mercury concentrations can affect plant reproduction, resulting in anomalies in gamete development and consequently loss of plant biodiversity.

Micromorphology, structural and ultrastructural changes during somatic embryogenesis of a Tunisian oat variety (Avena sativa L. var ‘Meliane’)

To better understand micromorphological and structural changes, histological sections provide additional insight into cellular process and developmental pathways occurring in oat somatic embryogenesis. Environmental scanning electron microscopy (ESEM) and transmission electron microscopy (TEM) were also used to follow the ultrastructural modifications during this system. Histological observations allowed following the events leading to the development of mature somatic embryos. The scheme includes the following steps: cell reactivation, the first organized cell division in diads, triads, tetrads as well as octant stages, the observation of an extracellular matrix (ECM) as a fibrillar material that bounded the surface of individualized proembryos. The transition from proembryo stage to an early globular somatic embryo was noted, where the embryogenic cortex is surrounded by the protoderm. The late globular stage was marked by bipolarity. The early and late transitional stages, the coleoptilar, mature and germinated stages were also described. The ESEM allowed us to follow some rearrangements, related to the morphology and surfaces involved in somatic embryos development. These events are proembryo formation, transition from proembryo to globular stage, marked by protoderm formation, scutellum and coleoptile development and finally somatic embryos germination. The TEM showed that embryogenic cells were very rich in organelles; mitochondria, rough endoplasmic reticulum, Golgi apparatus and ribosomes. Cells of proembryos, globular and late somatic embryos showed more vacuoles and differentiated organelles. The ECM was also detected by TEM as fibrillar material coating the cell walls. These results on structural and ultrastructural changes provided new insights and findings on oat somatic embryogenesis.

High-Throughput Image Analysis of Fibrillar Materials: A Case Study on Polymer Nanofiber Packing, Alignment, and Defects in Organic Field Effect Transistors.

High-throughput discovery of process-structure-property relationships in materials through an informatics-enabled empirical approach is an increasingly utilized technique in materials research due to the rapidly expanding availability of data. Here, process-structure-property relationships are extracted for the nucleation, growth, and deposition of semiconducting poly(3-hexylthiophene) (P3HT) nanofibers used in organic field effect transistors, via high-throughput image analysis. This study is performed using an automated image analysis pipeline combining existing open-source software and new algorithms, enabling the rapid evaluation of structural metrics for images of fibrillar materials, including local orientational order, fiber length density, and fiber length distributions. We observe that microfluidic processing leads to fibers that pack with unusually high density, while sonication yields fibers that pack sparsely with low alignment. This is attributed to differences in their crystallization mechanisms. P3HT nanofiber packing during thin film deposition exhibits behavior suggesting that fibers are confined to packing in two-dimensional layers. We find that fiber alignment, a feature correlated with charge carrier mobility, is driven by increasing fiber length, and that shorter fibers tend to segregate to the buried dielectric interface during deposition, creating potentially performance-limiting defects in alignment. Another barrier to perfect alignment is the curvature of P3HT fibers; we propose a mechanistic simulation of fiber growth that reconciles both this curvature and the log-normal distribution of fiber lengths inherent to the fiber populations under consideration.

Taxonomic contribution to the genus Sphaerosyllis (Annelida: Syllidae: Exogoninae) in the Black Sea.

During a study of fauna associated with a shallow-water Zostera (Zosterella) noltei bed from the southern part of the Romanian Black Sea coast, among the identified material collected in 2015, a syllid polychaete belonging to the subfamily Exogoninae, Sphaerosyllis taylori Perkins, 1981, represents a new record for the Black Sea. Re-examination of available specimens previously identified as Sphaerosyllis bulbosa Southern, 1914 revealed that they belong to an unknown species, described herein as Sphaerosyllis pontica sp. nov. The new species is characterized by the median antenna inserted more posteriorly than the lateral antennae, dorsal cirri with bulbous bases and very short tips, shorter than the parapodial lobes, dorsal cirri absent on chaetiger 2, parapodial glands with fibrillar material from chaetiger 4 onwards, compound chaetae with short blades and smooth shafts, anterior parapodia with two aciculae each, one straight and one with bent tip. Descriptions of both species are provided together with a key to all Sphaerosyllis species known from the Black Sea.

Cold Crystallization of Glassy Polylactide during Solvent Crazing.

Uniaxial tension accompanied by the orientation and crystallization of polymer chains is one of the powerful methods for the improvement of mechanical properties. Crystallization of amorphous isotropic polylactide (PLA) at room temperature is studied for the first time during the drawing of films in the presence of liquid adsorption-active media (ethanol, water-ethanol mixtures, and n-heptane) by the solvent crazing mechanism. The crystalline structure arises only under simultaneous actions of a liquid medium and a tensile stress and does not depend on the nature of the environment. The degree of polymer crystallinity increases nearly linearly with the growth in the fraction of the fibrillar material and reaches a maximum value of 42-45%. It has been stated that polymer crystallization happens in crazes involving nanofibrils with a diameter of about 10-20 nm without affecting the bulk polymer parts. Wide-angle X-ray scattering has been used to confirm that the crazing-induced crystallization is accompanied by the formation of the α'-crystalline phase with crystallite sizes (X-ray coherent scattering region) of 3-5 nm, depending on the nature of the liquid medium. After stretching in liquid media to a high tensile strain, the strength of a PLA film has increased to 200 MPa.

Physicochemical characterization of chitin from the Mediterranean flour moth, Ephestia kuehniella Zeller (Lepidoptera: Pyralidae)

ABSTRACTMoth chitin was extracted from adult of the Mediterranean flour moth by alkali-acid treatment and its characteristics were investigated and compared with shrimp chitin because the specific applications of chitin is directly associated with its physicochemical properties. The results revealed that the moth contained significant amounts of chitin but lower amounts of minerals. Fourier transform infrared spectroscopy (FT-IR), elemental analysis (EA), scanning electron microscopy (SEM) and energy dispersive x-ray diffraction (EDX) were used to investigate physicochemical characteristics of chitin samples. FT-IR spectra revealed that the moth chitin had α-chitin form (anti-parallel chains) with respect to the different orientations of its microfibrils. The degree of acetylation of chitin from moth and shrimp calculated using the FT-IR stretching bands were 70.82% and 71.42%, respectively. The SEM observation exhibited the presence of fibrillar material and porous structures in surface of the chitin samples. EDX analysis revealed that the main elements present in the moth chitin (beyond C, O and N) were Br (10.5%) and Si (9.7%). Our study of enzymatic activity toward colloidal chitin as substrate showed that the extracted chitin from E. kuehniella had high chemical purity as well as commercial chitin.

Ovarian nests in cultured females of the Siberian sturgeon Acipenser baerii (Chondrostei, Acipenseriformes).

Ovaries of Acipenser baerii are of an alimentary type and probably are meroistic. They contain ovarian nests, individual follicles, inner germinal ovarian epithelium, and fat tissue. Nests comprise cystoblasts, germline cysts, numerous early previtellogenic oocytes, and somatic cells. Cysts are composed of cystocytes, which are connected by intercellular bridges and are in the pachytene stage of the first meiotic prophase. They contain bivalents, finely granular, medium electron dense material, and nucleoli in the nucleoplasm. Many cystocytes degenerate. Oocytes differ in size and structure. Most oocytes are in the pachytene and early diplotene stages and are referred to as the PACH oocytes. Oocytes in more advanced diplotene stage are referred to as the DIP oocytes. Nuclei in the PACH oocytes contain bivalents and irregularly shaped accumulation of DNA (DNA-body), most probably corresponding to the rDNA-body. The DNA-body is composed of loose, fine granular material, and comprises multiple nucleoli. At peripheries, it is fragmented into blocks that remain in contact with the inner nuclear membrane. In the ooplasm, there is the rough endoplasmic reticulum, Golgi complexes, free ribosomes, complexes of mitochondria with cement, fine fibrillar material containing granules, and lipid droplets. The organelles and material of nuclear origin form a distinct accumulation (a granular ooplasm) in the vicinity of the nucleus. Some of the PACH oocytes are surrounded by flat somatic cells. There are lampbrush chromosomes and multiple nucleoli present (early diplotene stage) in the nucleoplasm. These PACH oocytes and neighboring somatic cells have initiated the formation of ovarian follicles. The remaining PACH oocytes transform to the DIP oocytes. The DIP oocytes contain lampbrush chromosomes and a DNA-body is absent in nuclei. Multiple nucleoli are numerous in the nucleoplasm and granular ooplasm is present at the vegetal region of the oocyte.

Multiple viral plaques with sebaceous differentiation associated with an unclassified papillomavirus type in a cat

CASE HISTORY AND CLINICAL FINDINGSA 15-year-old neutered male domestic short-haired cat was presented due to multiple 0.5–2 cm-diameter crusting plaques in the left preauricular region, over the bridge of nose, and in the right periocular region. The plaques did not appear to cause discomfort.HISTOPATHOLOGICAL FINDINGSBiopsy samples of four plaques were examined histologically. Three plaques consisted of well-demarcated foci of mild epidermal hyperplasia overlying markedly hyperplastic sebaceous glands. Approximately 60% of the hyperplastic cells contained a large cytoplasmic vacuole that ranged from being clear to containing prominent grey-blue fibrillar material. The fourth plaque was composed solely of epidermal hyperplasia, consistent with previous descriptions of feline viral plaques.MOLECULAR BIOLOGYPapillomavirus DNA was amplified from all four plaques using PCR. A single DNA sequence was amplified from the plaques with sebaceous differentiation. This sequence was identical to the FdPV-MY sequence previously suggested to be from a putative unclassified papillomavirus type. Felis catus papillomavirus type 2 sequences were amplified from the plaque typical of feline viral plaques. Immunohistochemistry to detect p16CDKN2A protein (p16) showed marked immunostaining throughout the hyperplastic epidermis and adnexal structures within the plaques with sebaceous differentiation.DIAGNOSISMultiple feline viral plaques with variable sebaceous differentiation.CLINICAL RELEVANCEFeline viral plaques with sebaceous differentiation have not been previously reported in cats. The presence of unique cell changes within these lesions, the detection of an unclassified papillomavirus type, and the p16 immunostaining within these plaques suggest that they may have been caused by the papillomavirus that contains the FdPV-MY sequence.