Development and changes of annulate lamellae complexes in rubella virus-infected RK-13 cells

Data-driven discovery of high performance layered van der Waals piezoelectric NbOI2

Using high-throughput first-principles calculations to search for layered van der Waals materials with the largest piezoelectric stress coefficients, we discover NbOI₂ to be the one among 2940 monolayers screened. The piezoelectric performance of NbOI₂ is independent of thickness, and its electromechanical coupling factor of near unity is a hallmark of optimal interconversion between electrical and mechanical energy. Laser scanning vibrometer studies on bulk and few-layer NbOI₂ crystals verify their huge piezoelectric responses, which exceed internal references such as In₂Se₃ and CuInP₂S₆. Furthermore, we provide insights into the atomic origins of anti-correlated piezoelectric and ferroelectric responses in NbOX₂ (X = Cl, Br, I), based on bond covalency and structural distortions in these materials. Our discovery that NbOI₂ has the largest piezoelectric stress coefficients among 2D materials calls for the development of NbOI₂-based flexible nanoscale piezoelectric devices.

The recent thrust toward flexible nanoscale devices creates a need for two-dimensional piezoelectric materials. Here, the authors find large piezoelectric response in NbOI₂ flakes ranging from 4 nm to the bulk.

Annulate lamellae and intracellular pathogens

Annulate lamellae (AL) have been observed many times over the years on electron micrographs of rapidly dividing cells, but little is known about these unusual organelles consisting of stacked sheets of endoplasmic reticulum-derived membranes with nuclear pore complexes (NPCs). Evidence is growing for a role of AL in viral infection. AL have been observed early in the life cycles of the hepatitis C virus (HCV) and, more recently, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), suggesting a specific induction of mechanisms potentially useful to these pathogens. Like other positive-strand RNA viruses, these viruses induce host cells membranes rearrangements. The NPCs of AL could potentially mediate exchanges between these partially sealed compartments and the cytoplasm. AL may also be involved in regulating Ca²⁺ homeostasis or cell cycle control. They were recently observed in cells infected with Theileria annulata, an intracellular protozoan parasite inducing cell proliferation. Further studies are required to clarify their role in intracellular pathogen/host-cell interactions.

Modifications of nuclear envelope during differentiation and depolyploidization of rat trophoblast cells

An increased activity of membranes of the nuclear envelope (NE) was observed electron microscopically in the trophoblast cells of the rat placenta. The activity of the membranes was manifested as formation of various NE derivatives, such as the annulate lamellae (AL), the intranuclear tubules, and the concentric membranous structures. At the period of terminal differentiation of the secondary giant trophoblast cells (SGTC) the NE derivatives play active role in subdivision of the initial highly polyploid nuclei into the numerous low-ploidy fragments. (3)H-thymidine labeling showed that attenuation of the DNA replication precedes the nuclear fragmentation. In the course of the nuclear fragmentation the narrow deep NE invaginations subdivide the nucleus into the separate lobes that subsequently are detached from the initial nucleus. By the beginning of the fragmentation, the accumulated membranous structures, i.e. the intranuclear AL, tubules, clusters of pore complexes, etc., seem to be the source of the reserve material that is necessary for formation of the great amount of the NE membranes of the newly formed nuclear fragments. Thus, the intranuclear membranous structures that seem to increase the active surface of the growing endopolyploid nucleus at the earlier stage of differentiation then take part in genome isolation that results in formation of a multinucleate cell with diploid and low-polyploid nuclei. The outer NE membrane of the initial nucleus plays an active role in compartmentalization of cytoplasmic areas around the nuclear fragments within the giant polykaryocyte. Apart from the membranous structures the bundles of intermediate filaments (IF) located in the cytoplasm perinuclear zones seem to participate in the nuclear fragmentation. These processes are likely to provide formation of the giant polykaryocytes incapable for further proliferation.

Rubella virus replication and links to teratogenicity

Rubella virus (RV) is the causative agent of the disease known more popularly as German measles. Rubella is predominantly a childhood disease and is endemic throughout the world. Natural infections of rubella occur only in humans and are generally mild. Complications of rubella infection, most commonly polyarthralgia in adult women, do exist; occasionally more serious sequelae occur. However, the primary public health concern of RV infection is its teratogenicity. RV infection of women during the first trimester of pregnancy can induce a spectrum of congenital defects in the newborn, known as congenital rubella syndrome (CRS). The development of vaccines and implementation of vaccination strategies have substantially reduced the incidence of disease and in turn of CRS in developed countries. The pathway whereby RV infection leads to teratogenesis has not been elucidated, but the cytopathology in infected fetal tissues suggests necrosis and/or apoptosis as well as inhibition of cell division of critical precursor cells involved in organogenesis. In cell culture, a number of unusual features of RV replication have been observed, including mitochondrial abnormalities, and disruption of the cytoskeleton; these manifestations are most probably linked and play some role in RV teratogenesis. Further understanding of the mechanism of RV teratogenesis will be brought about by the investigation of RV replication and virus-host interactions.

Rubella virus replication and links to teratogenicity

Rubella virus (RV) is the causative agent of the disease known more popularly as German measles. Rubella is predominantly a childhood disease and is endemic throughout the world. Natural infections of rubella occur only in humans and are generally mild. Complications of rubella infection, most commonly polyarthralgia in adult women, do exist; occasionally more serious sequelae occur. However, the primary public health concern of RV infection is its teratogenicity. RV infection of women during the first trimester of pregnancy can induce a spectrum of congenital defects in the newborn, known as congenital rubella syndrome (CRS). The development of vaccines and implementation of vaccination strategies have substantially reduced the incidence of disease and in turn of CRS in developed countries. The pathway whereby RV infection leads to teratogenesis has not been elucidated, but the cytopathology in infected fetal tissues suggests necrosis and/or apoptosis as well as inhibition of cell division of critical precursor cells involved in organogenesis. In cell culture, a number of unusual features of RV replication have been observed, including mitochondrial abnormalities, and disruption of the cytoskeleton; these manifestations are most probably linked and play some role in RV teratogenesis. Further understanding of the mechanism of RV teratogenesis will be brought about by the investigation of RV replication and virus-host interactions.

Annulate lamellae and lytic HAV infection in vitro

The aim of this study was to examine the relationship between viral infection and annulate lamellae (AL) production by using quantitative and qualitative electron microscopy to document the size and numbers of AL in BS-C-1 cells infected with a lytic strain of hepatitis A virus (HAV). The progress of the HAV infection was found to occur in two phases. In phase 1, cell proliferation and cell death were roughly the same as that of the mock infected control, but there was an increase with time in the amount of hepatitis A antigen in the infected cells. In phase 2 cell division was minimal and cell death became manifest. AL were detected in both infected and control cells. Quantitative analysis indicated that the average number of AL was greater in infected cells compared to that in control cells in phase 1; in infected cells there were greater numbers of AL in phase 1 than in phase 2; the average number of membraneous leaves/AL was greater in infected cells than in control cells. Quantitative analysis also indicated that AL were very rare, with only about three AL per entire control cell and eight AL per entire infected cell. The study clearly establishes that viral infection can stimulate AL production. The data suggest stimulation of AL production in the virus infected cells was linked to the synthesis of viral antigen. Ultrastructural observations indicated that AL could be derived from either the rough endoplasmic reticulum or the nuclear membrane.

Molecular biology of rubella virus

This chapter summarizes the present medical significance of rubella virus. Rubella virus infection is systemic in nature and the accompanying symptoms are generally benign, the most pronounced being a mild rash of short duration. The most common complication of rubella virus infection is transient joint involvement such as polyarthralgia and arthritis. The primary health impact of rubella virus is that it is a teratogenic agent. The vaccination strategy is aimed at elimination of rubella and includes both universal vaccination of infants at 15 months of age with the trivalent measles, mumps, rubella (MMR) vaccine and specific targeting with the rubella vaccine of seronegative women planning pregnancy and seronegative adults who could come in contact with women of childbearing age, although it is recommended that any individual over the age of 12 months without evidence of natural infection or vaccination be vaccinated. Medically, the current challenge posed by rubella virus is to achieve complete vaccination coverage to prevent resurgences.

Morphological changes in HAV-infected Frp/3 cells and immunolocalization of HAAg

Electron and immunoelectron microscopic studies were carried out on HAV-infected Frp/3 cells. The infection led to a distinctive cytopathic effect (CPE) arising on day 3 up to the complete detachment of monolayers on day 7. Infected cells exhibited progressive modifications, beginning from the formation of long helical polyribosomes. Subsequently, hypertrophy, cisternal dilatation and degranulation of the RER could be observed. Furthermore, the formation of concentric membranous bodies (CMB), large myelin-like structures and annulate lamellae could be revealed at later times of infection. 24-27 nm virus-like particles were observed within cytoplasmic vesicles or outside extensively degenerated cells. Indirect immunoperoxidase staining were used to localize HAV antigen (HAAg) in thin sectioned infected Frp/3 cells. Vesicular inclusion bodies, often seen to contain electron-lucent particles, resulted darkly stained as well as tracts of the RER and myelin-like structures. Negatively stained preparations from cell lysates revealed small clusters of HAV particles which sometimes appeared to be still associated with residual membrane fragments. Our findings seem to suggest that HAV replication occurs in close association with cytoplasmic membranes and a direct involvement of the RER seems to be demonstrated.

The annulate lamellae--from obscurity to spotlight

This review aims to provide a comprehensive and in-depth survey of a cell organelle, the annulate lamellae, that is widely distributed and especially prevalent in both female and male sex cells as well as tumor and cancer cells. The organelle is also present in many somatic cells and plant cells. Emphasis is placed on the contributions that electron microscopy and associated experimental approaches have made in providing information about the distribution, ultrastructure, morphogenesis and relationships of annulate lamellae to other cellular organelles, especially the nuclear envelope and endoplasmic reticulum, as well as cell product. An increasing number of experimental manipulations have recently been shown to alter, either increase or decrease, the amount of annulate lamellae and these studies are explored in depth. Information about the origin and morphogenesis of annulate lamellae in different cells is summarized and extensive coverage is given to several hypotheses about possible annulate lamellae function. A detailed bibliography provides a thorough compilation of research dealing with annulate lamellae. A major goal of this extensive review is to generate increased awareness of, and interest in, this cell organelle for students and investigators of the cell who, by bringing current techniques in cell and molecular biology to bear, might focus and intensify studies on the function of an organelle whose precise role in the cell is presently enigmatic.

Cellular changes associated with persistent hepatitis A infection in vitro

The rate of division, morphology and ultrastructure of BSC-1 cells, persistently infected with hepatitis A virus (HAV), were compared with uninfected cells for 60 days after splitting of the cells. Both control and infected cells showed a biphasic growth pattern marked firstly by increasing cell density and high mitotic rate (exponential phase) and then high constant cell density and little mitosis (stationary phase). Immunoperoxidase studies showed that hepatitis A antigen (HAAg) appeared as cytoplasmic granules approximately one third of the way through the exponential phase in infected cells. The percentage of cells with HAAg rose until the early stationary phase when virtually all cells contained antigen. Radioimmunoassay demonstrated an increase in HAAg per cell in the stationary phase. Radioimmunofocus assay and immune electron microscopy confirmed the presence of HAV in infected cells in the stationary phase. Thin sectioning electron microscopy showed cytoplasmic annulate lamellae in infected cells of both phases but not in control cells.

Unusual intracytoplasmic lamellar bodies in a malignant gonadal stromal tumor

Characteristic intracytoplasmic lamellar bodies were found in a malignant gonadal stromal tumor. These bodies consisted of the stacks of up to 200 tubular cisternae arranged in parallel. Each cisterna had a circular section in tangential view and a diameter of about 85 nm. The cisternae on the outermost side of these lamellar bodies tended to be dilated and adorned with ribosomes. The ends of cisternae were often contiguous with rough-surfaced endoplasmic reticulum. The latter feature is also seen in annulate lamellae, but periodically spaced annuli or discontinuities characteristic of annulate lamellae were never observed. Furthermore, fine ribosomal granules resembling a rosary were recognizable along the whole circumference of the outer surface of each cisterna. The unique structure we describe is a cytoplasmic organelle which, like annulate lamellae, is closely associated with the endoplasmic reticulum and is presumed to be related to the genesis of rough-surfaced endoplasmic reticulum in tumor cells.

The coexistence of ribosome-lamella complex and annulate lamellae in chronic lymphocytic leukemia

An electron microscopic study of peripheral blood and lymph node from a patient with chronic lymphocytic leukemia revealed ribosome-lamella complexes in 11-16% of the peripheral lymphocytes and in 14% of the nodal lymphocytes. Annulate lamellae were seen in 2-8% of the peripheral lymphocytes and in 8% of the nodal lymphocytes. One peripheral blood specimen revealed coexistence annulate lamellae and ribosome-lamella complexes within the same cells in an additional 4% of the lymphocytes. The two structures were connected by continuous strands of apparent endoplasmic reticulum. Although annulate lamellae and ribosome-lamella complex have each been described in chronic lymphocytic leukemia, albeit uncommonly, their unusual association with one another has not previously been documented and might offer a clue as to the origin and role of these interesting structure. The possible ramifications of these observations include relationship of the structures to endoplasmic reticulum and protein synthesis, to in vitro and possible clinical induction by drugs including "antitubulins," and to induction in vitro by viral infection.

Morphological observations of the replication of herpesvirus tamarinus in RL-33 cells

The replication in RL-33 cells (rabbit lung cell line) of herpesvirus tamarinus isolated from cotton-topped marmosets (Saguinus oedipus) was investigated by electron microscopy. In the early stages of infection, ring-shaped and granular structures, and fibrillar materials were recognized in the nucleus. Immature particles were often found in such nuclei. The envelope of the virus was formed by budding through intracytoplasmic membranes, the inner nuclear membrane or the membrane of intracytoplasmic vacuoles. Virus particles which appeared to be budding through the plasma membrane were also observed. Aberrant viral forms were produced by independent budding of both the inner and outer nuclear membranes. The mature particles once enveloped acquired a second envelope by budding through intracytoplasmic double membranes or the outer nuclear membrane. Unusual virus-associated structures were observed in the cytoplasm and nucleus. Virus particles appeared to be released by the process of reverse phagocytosis.

Canine transmissible venereal sarcoma: electron microscopic changes with time after transplantation

The structure of canine transmissible venereal sarcoma (CTVS) has been examined from 14 to 71 days after implantation. During early growth, the tumour appears to be composed primarily of loosely arranged, round cells and a few fibroblast-like cells. As the tumour mass increases, the round cells become tightly packed with highly interdigitating plasma membranes. The number of irregularly shaped round cells and fibroblast-like cells increases with increasing tumour mass. Collagen and reticular fibres can be found in early tumours, frequently in association with the round cells, and in regions devoid of fibroblast-like cells. During tumour regression, cellular degradation is evident in fibroblast-like and irregularly shaped cells as well as round cells. The data suggest that transformation may occur in the course of tumour growth, causing morphological change from round to fibroblast-like cells, and that CTVS is an undifferentiated round-cell sarcoma capable of differentiation in a fibroblastic direction. Also present, primarily in tumour cells from newborn dogs, are cytoplasmic lamellar arrays and crystalline virus-like structures, both previously described in other forms of tumor cells.

Fine structural study of annulate lamellae complexes in human tumors

Specific intracytoplasmic organelles, annulate lamellae and radial cisternae, have been studied in several human tumours. Annulate lamellae are observed in all cases of leiomyoma, leiomyosarcoma, rhabdomyosarcoma and malignant melanoma, whereas radial cisternae are only found in a case of leiomyosarcoma. Annulate lamellae are characterized by stacks of parallel arrayed long cisternae showing alternative arrangement of annuli and sacs. Some of these cisternae are connected directly with rough-surfaced endoplasmic reticulum and there is continuity with the lumen and membrane. Radial cisternae are mainly composed of two structures: numerous short cisternae, which are a variant of annulate lamellae, and numerous spherical particles derived from the cisternae. The cisternae are arranged parallel or radially around particles measuring up to 1100 A in diameter. These particles consisting of an amorphous high electron dense material without distinct limiting membrane are organized in groups and vary in number. There is no evidence of a direct relationship between these structures and viral infection.