Formation Of Binucleated Cells Research Articles

The cytogenetics ofLotus(Leguminosae)

Chromosome numbers for 108 species of the genus Lotus (Leguminosae) are now known. This represents an increase of 32 new species which have been reported since a chromosome atlas for Lotus was published in 1965. At this rate, with just over one chromosome number being reported for a new species per year, it will require almost a century for the chromosome numbers to be determined for all of the species in the genus. A review of the cytogenetic features which have been observed in the genus through karyotype analyses, chromosome banding, Feulgen cytophotometry, anther culture, HCN reaction and interspecific hybridization is presented. These include cytomixis and B chromosomes (both found in hybrids of diploid species in the L. corniculatus group when L. alpinus was one of the parents), desynapsis, binucleate cell formation, polytene chromosomes in suspensor cells and trisomics in L. pedunculatus. There has been a reduction of HCN content in the species with evolutionary development which is correlated with...

Binucleate Cell Formation Correlates to Loss of Colony-Forming Ability in X-Irradiated Cultured Mammalian Cells

The relationship between binucleate cell formation and the loss of colony-forming ability was examined in several cultured mammalian cell lines irradiated with X rays. The maximum fraction of binucleate cells after X irradiation increased dose-dependently within the range in which reproductive cell death might predominate over interphase cell death. When the logarithm of percentage survival was plotted against the percentage binucleate cells, a similar correlation was found for all cell lines tested, with the exception of mouse leukemia L5178Y cells, the most radiosensitive cells used. These observations suggest that the fraction of binucleate cells in the cell population can serve as a measure of cellular radiation damage.

Studies of erythroblast function in congenital dyserythropoietic anaemia, type I: evidence of impaired DNA, RNA, and protein synthesis and unbalanced globin chain synthesis in ultrastructurally abnormal cells.

Two patients with congenital dyserythropoietic anaemia, type I (CDA) were studied. Their blood reticulocytes showed unbalanced globin chain synthesis with increased alpha:beta globin chain synthesis ratios. A high proportion of the erythroblasts displayed the characteristic "Swiss cheese" abnormality of the nuclear chromatin and some also showed cytoplasmic intrusions lined with nuclear membrane within the nucleus. Occasional erythroblast profiles contained intracytoplasmic inclusions that were ultrastructurally indistinguishable from precipitated alpha chains. The technique of combined Feulgen microspectrophotometry and 3H-thymidine autoradiography showed gross abnormalities of proliferation in the early polychromatic erythroblasts. The proliferative abnormalities included an arrest of DNA synthesis after the progress of cells through part of the S phase and the formation of several mononucleate and binucleate cells with hypertetraploid total DNA contents. The bone marrow cells gave a normal deoxyuridine suppressed value, indicating that there was no impairment of the methylation of deoxyuridylate. Electron microscope autoradiographic studies showed that a high proportion of the erythroblasts with the "Swiss cheese" nuclear abnormality suffered from a severe impairment, or arrest of DNA, RNA, and protein synthesis.

An ultrastructural study of binucleate plasma cells.

Fifty surgical specimens from 10 different diseases were examined for the presence of binucleate plasma cells. Thirty-three specimens showed binucleated plasma cells. Morphologically, they resembled mononuclear cells and contained abundant basophilic cytoplasm which ultra-structurally showed extensive rough endoplasmic reticulum. Their 2 nuclei exhibited the "cart-wheel" arrangement of heterochromatin characteristic of plasma cells. When serially examined the 2 nuclei remained separate. In addition, pairs of closely apposed plasma cells were observed. Some of these cells showed distinct apposing membranes separated by a gap of approximately 15 nm. While others, exhibited localised areas of indistinct membranes. There were also pairs of closely apposed plasma cells showing cytoplasmic bridges. These results suggest that the mode of formation of binucleate plasma cells is probably cell fusion. They also show that these binucleate cells are not confined to a single disease as they were found in 10 different diseases.

Pathogenesis of ventricular hypertrophy

Growth of the vertebrate heart during embryonic and fetal life is characterized by hyperplasia of myocardial cells. Shortly after birth, myocardial cells lose the capability of dividing, and further growth of the heart is due to myocardial cell hypertrophy and nonmuscle cell hyperplasia. This process results in a 30- to 40-fold increase in volume of individual myocardial cells during normal postnatal growth and maturation. The transition from hyperplastic to hypertrophic growth is related to formation of binucleated myocardial cells as a result of karyokinesis without cytokinesis. The molecular mechanism of this transition is uncertain. The response of the heart to increased metabolic demands or an increased work load depends on the age of the animal at the time when the stress is imposed. Increased myocardial work loads in fetal or early neonatal life lead to cardiac enlargement by causing an increased rate of hyperplasia of myocardial cells or continuation of hyperplasia beyond the normal period of hyperplastic growth. In contrast, imposition of increased loads on the hearts of older animals results in cardiac hypertrophy due to enlargement of myocardial cells and hyperplasia of nonmuscular components. In addition to cellular enlargement, structural remodeling of the myocardial cells and of the chambers of the heart occurs during the development of hypertrophy. Important stimuli of cardiac hypertrophy include increased systolic force or tension generated by the myocardial fibers (pressure overload), increased end-diastolic wall stress (volume overload) and neurohumoral factors such as increased circulating catecholamines or discharge of cardiac sympathetic nerves, or both, activation of the renin-angiotensin system and increased levels of thyroxine and growth hormone.(ABSTRACT TRUNCATED AT 250 WORDS)

Interaction of triethyl lead chloride with microtubules in vitro and in mammalian cells

The effects of triethyl lead chloride (TriEL) on the in vitro assembly and disassembly of microtubules (MTs) from porcine brain were studied by turbidometry at 350 nm and by electron microscopy. TriEL inhibited MT assembly at 50 μM concentration and caused an almost complete disassembly of preformed MTs. The drug depolymerized MTs more effectively than colchicine. Concentrations higher than 50 μM TriEL caused an aberrant assembly process. Fibers about 10 nm width were formed in addition to aggregates of amorphous material. In vivo TriEL also caused MT depolymerization in interphase and mitotic PtK-1 and Ehrlich ascites tumor (EAT) cells as monitored by indirect immuno-fluorescent staining of tubulin and electron microscopy. The extent of MT depolymerization was concentration- and time-dependent. Recovery occurred as early as 5 min after removal of the drug. The fluorescent actin pattern in PtK-1 cells typical of stress fibers and subcortical filaments seemed not to be altered by the presence of TriEL. The vimentin intermediate filament system was, however, rearranged as a juxtanuclear complex after TriEL treatment. Furthermore, TriEL effected the inhibition of cellular growth (100% inhibition at about 10 −5 M). Cytokinesis is prevented to a great extent, resulting in the formation of binucleate cells which can additionally possess some micronuclei.

Distribution of Chromosomes into Discrete Groups in Colchicine-Induced C-Metaphases of Barley

SUMMARYRoots of barley were treated with 0.1–0.01% solutions of colchicine. After treatment with 0.1% or 0.05% colchicine, c-metaphases were seen in which chromosomes, each consisting of two sister-chromatids, were distributed into 2, and rarely into > 2, distinct groups. Each group of chromosomes gave rise to a restitution nucleus. The result of these distributive c-mitoses was the formation of binucleate or multinucleate cells. The pattern of distribution of the diploid complement of 14 chromosomes has been determined. It was not random: 7:7 distributions were relatively infrequent but 6:8 or 4:10 distributions occurred in high frequencies. This could result from the arrangement of chromosomes as they were released from the prophase nucleus but it appears also to involve movement of chromosomes, probably under the influence of cytoskeletal components. Bi- and multinucleate cells completed interphase and divided. In most of the binucleate cells, the two nuclei entered prophase in synchrony but a low perc...

Myocardial cell hypertrophy or hyperplasia.

Growth of the vertebrate heart during embryonic and fetal life is characterized by hyperplasia of myocardial cells; these cells increase in number to a value characteristic for each species. Shortly after birth myocardial cells lose the capability of dividing, and further growth of the heart is due to myocardial cell hypertrophy and nonmuscle cell hyperplasia. This process, which is referred to as hypertrophic growth, results in a 30- to 40-fold increase in volume of individual myocardial cells during normal postnatal growth and maturation. The transition from hyperplastic to hypertrophic growth is related to formation of binucleated myocardial cells as a result of karyokinesis without cytokinesis. The molecular mechanism of this transition is uncertain. The response of the heart to increased metabolic demands or to an increased workload depends on the age of the animal at the time the stress is imposed. Increased myocardial workloads due to systemic hypertension, chronic hypoxia, or carbon monoxide exposure in fetal or early neonatal life lead to cardiac enlargement by causing an increased rate of hyperplasia of myocardial cells or continuation of hyperplasia beyond the normal period of hyperplastic growth. In contrast, imposition of increased loads on the hearts of older animals results in cardiac hypertrophy due to enlargement of myocardial cells and hyperplasia of nonmuscular components. In addition to cellular enlargement, structural remodeling of the myocardial cells, including alterations in the relative proportions of cellular organelles and in the ultrastructure of individual organelles, occurs during the development of hypertrophy in the adult heart.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of 9-(2,3-dihydroxypropyl) adenine (DHPA) on seedling roots ofVicia faba L. in comparison with adenine, adenosine and some cytokinins

3-day-old seedlings ofVicia faba L. were put onto a diluted Knop’s solution containing the tested substances within the intentional concentration range and left there for 7 days. In comparison with controls in plain nutrient solution, the DHPA treated plants revealed a suppression of shoot and root development. The main root growth was less sensitive than root branching. 8 h exposure was sufficient to gain a distinct effect. Microscopically the block of mitosis and/or cytokinesis, the formation of binucleate cells and local tissue damage were revealed. Under the given conditions, the cytokinins (BAP, (9R)BAP, iP, (9R)iP) proved to be much more powerful inhibitors than DHPA, whereas adenine and adenosine were less impairing.

Distribution of Chromosomes into Discrete Groups in Colchicine-Induced C-Metaphases of Barley

SUMMARYRoots of barley were treated with 0.1–0.01% solutions of colchicine. After treatment with 0.1% or 0.05% colchicine, c-metaphases were seen in which chromosomes, each consisting of two sister-chromatids, were distributed into 2, and rarely into > 2, distinct groups. Each group of chromosomes gave rise to a restitution nucleus. The result of these distributive c-mitoses was the formation of binucleate or multinucleate cells. The pattern of distribution of the diploid complement of 14 chromosomes has been determined. It was not random: 7:7 distributions were relatively infrequent but 6:8 or 4:10 distributions occurred in high frequencies. This could result from the arrangement of chromosomes as they were released from the prophase nucleus but it appears also to involve movement of chromosomes, probably under the influence of cytoskeletal components. Bi- and multinucleate cells completed interphase and divided. In most of the binucleate cells, the two nuclei entered prophase in synchrony but a low percentage of asynchronous divisions were seen. The division of binucleate cells is related to the formation of homozygous cell lineages in colchicine treated plants.

Retinal pigment epithelium: pattern of proliferative activity and its regulation by intraocular pressure in postnatal rats

The postnatal proliferative activity of retinal pigment epithelium (RPE) cells and its dependence on intraocular pressure were studied using [3H]thymidine and [14C]thymidine autoradiography in normal and experimentally induced microphthalmic pigmented rats. The regulation of RPE growth by intraocular pressure was shown to involve the control of the number of binucleated cells by means of stimulation of cell entry into the S phase of the cell cycle. Binucleated cells in the rat RPE are formed by acytokinetic mitoses between days 2 and 9. The significance of the postnatal proliferation and formation of binucleated cells in the RPE is discussed in terms of the specificity of the G2 phase for melanotropic hormone action on RPE differentiation.

Inhibition of cytokinesis and altered contractile ring morphology induced by cytochalasins in synchronized PtK2 cells

PtK2 cells and antigen affinity-purified antibodies to actin and tubulin were used to study the effects on mitosis of cytochalasin B (CB) and dihydrocytochalasin B (H 2CB). PtK2 cells were synchronized in S phase by a double thymidine block and CB or H 2CB was added at various concentrations at the time of release from the block. CB- and H 2CB-treated populations, and control populations not treated with either drug, progressed synchronously through G2 and into mitosis with similar time courses. By both phase contrast and immunofluorescence microscopy, CB- and H 2CB-treated cells appeared normal in terms of chromosome condensation, spindle formation and spindle dynamics throughout prophase, metaphase and early anaphase. At late anaphase, contractile ring staining with actin antibody was not normal. High actin antigenicity remained localized in the region of the contractile ring; however, it appeared atypically as a punctate line of fluorescence across the midzone. Although some degree of furrowing was often seen to occur, at suitable concentrations of CB or H 2CB only binucleate G1 cells formed. Scanning electron microscopy (SEM) of normal and CB- and H 2CB-treated cells verified that cleavage furrowing did not proceed normally in treated cells. Large numbers of microvilli and surface blebs occurred in the normally smooth furrow region in these treated populations. These results suggest that intact microfilament function is not necessary for progression from S phase into mitosis, for spindle formation or for chromosome movement. They indicate that CB and H 2CB lead to formation of binucleated cells by causing aberrant cleavage furrowing and inhibition of contractile ring microfilaments.

Multinucleation and inhibition of cytokinesis in suspended cells: Reversal upon reattachment to a substrate

Cell proliferation under nonadhesive conditions was examined in anchorage-dependent mouse fibroblasts (3T3 and 3T6), in epithelial monkey kidney cells (BSC-1) and in four B16 melanoma cell variants that exhibit distinct metastatic properties. Non-adhesive conditions established by suspension culture in methyl cellulose or by plating on poly(2-hydroxyethylmethacrylate)-coated plates cause multinucleation and inhibition of cytokinesis in all cell types. Formation of binucleated cells in suspended 3T3 cells continues for 24 hr until DNA synthesis is completely inhibited. Twenty percent of the cells become binucleated during this time. During a similar period in suspension culture over 60% of a synchronized epithelial cell culture (suspended 8 hr after the initiation of S phase) became binucleated. The melanoma cells that maintain a high level of metabolism while in suspension continued to develop into multinucleated cells. After 3 days in suspension, 50% of the melanoma cells have more than one nucleus. Since cell number during suspension culture remains constant, because of a block in cytokinesis, there is a remarkable increae in cell size in suspended melanoma cells. When replated on tissue culture plates, normal cell division resumes by an early extrusion of the extra nuclei in melanoma cells. The melanoma cell variants, although displaying different metastatic potential in vivo, behave similarly in suspension culture. 3T3 cells require 24 hr of replating before recovering DNA synthesis and initiating extrusion of the extra nucleus. The results suggest a differential sensitivity of cytokinesis and karyokinesis to cell-surface contact with the substrate.

Inhibition of cell growth in roots of Allium cepa by caffeine and isobutylmethylxanthine

Roots of Allium cepa were treated for 1 hr with 0.1% solutions of caffeine or isobutylmethylxanthine (IBMX). Both compounds induce the formation of binucleate cells. Both compounds also inhibit growth of: (1) cells proceeding into mitosis during treatment; (2) late G 2-prophase nuclie. This response was found in random samples of cells and confirmed by studies of pairs of sister cells, one of which was in mitosis and one of which was in G 2. The results showed a marked inhibition of growth at the end of G 2 and during mitosis. The binucleate cells induced by treatment were studied over 1 cell cycle. The two sister nuclei were not identical in volume when first formed and the difference was subsequently maintained throughout interphase. The binucleate cells with the shortest cell cycle were in division 18 hr after treatment. Their mean cell area showed only a 1.58-fold increase over mean area in very early G 1, i.e. they did not double in area over a cell cycle. Diploid, mononucleate cells in division 18 hr after treatment, i.e. in division at the same time as binucleate cells, were significantly smaller than mitotic cells of untreated roots. This suggests that the response of these cells to treatment with methylxanthines is similar to that of binucleate cells. Mononucleate cells in mitosis at 1 + 18 hr had undergone only a 1.4-fold increase in cell area; this is much less than the doubling in mean cell area seen in untreated cells over one cycle. It appears that profound disturbances of cell and nuclear growth are induced in A. cepa by even a 1 hr treatment with caffeine or IBMX.

Amitosis: A Historical Misinterpretation?

"The problem of amitosis" (Bucher, 1971) has historical, theoretical, formal, and methodological aspects. Most cases of amitosis described during the past 125 years have proved to be misinterpretations of incomplete mitoses. Binucleate cells and occasionally dumbbell-shaped restitution nuclei are formed as the result of mitotic inhibitions, which increases with tissue differentiation. Until recently, binucleate cells in the myocardium have been interpreted as products of amitotic nuclear divisions, since mitoses are not found in human myocardium. However, mitoses are found in postnatal pig hearts fixed immediately after death. The mitotic index declines from 2.2% at day ten to 0.3% at day thirty during postnatal life. Delayed fixation yields degenerated prophase and telophase nuclei only. Thus the formation of binucleate myocardial cells and nuclear rows is the result of mitoses with impeded cellular divisions. To call these findings examples of amitosis is a misinterpretation.

Role of polyamines in cytokinesis of mammalian cells

Inhibition of polyamine biosynthesis in mammalian cells with methylglyoxal bis-(guanylhydrazone) and α-methyl ornithine inhibits cytokinesis and induces the formation of binucleate cells. Further, these binucleate cells exhibited a diffused pattern of microfilaments compared with the control cells as evidenced by indirect immunofluorescence using anti-actin antibodies. These effects can be reversed by increasing the intracellular levels of the polyamines. The results of this study suggest that polyamines may have a role in the process of cytokinesis and cell division.

Binucleate Cell Formation Induced by X Irradiation

The kinetics of binucleate cell formation and their relationship to the recovery of primary cell damage were investigated using mouse mammary carcinoma cells (FM3A) grown in suspension. The following results were obtained: (i) the percentage of binucleate cells increased with the dose to a maximum on the second or third day postirradiation when the rate of proliferation was at a minimum; (ii) the percentage of binucleate cells was smaller following two split doses (2 × 500 rad, at a 4-hr interval) than following a single (1000-rad) dose; and (iii) the percentage of binucleate cells decreased with treatment of the cells with Hanks' balanced salt solution (HBSS) immediately postirradiation (1000 rad). These results suggest that radiation-induced binucleate cell formation plays an important role in reproductive cell death.

Contribution to the Understanding of the Mechanism of Cytokinesis In Plant Cells: the Action of Deoxyguanosine On the Kinetics of A Root Meristem Cell Population

The kinetics of binucleate cells, formed by the action of deoxyguanosine, are studied using three methods: in a population synchronized with hydroxyurea, by autoradiography after pulse-labelling, and in a sample of a cell population morphologically located at the M--G1 limit. Deoxyguanosine induces a slowing down in S and G2, independent of the inhibition of cytokinesis. It is only when it takes effect during the G2 stage that deoxyguanosine brings about the formation of binucleate cells.

The stimulation of DNA synthesis by cytochalasin B in proliferative epidermal and dermal cells

Cytochalasin B influences a variety of cellular events that are associated with the contractile microfilament system and the formation of binucleate cells. Along with the formation of binucleate cells, cytochalasin B also causes an acceleration of cells from G1 to S in the cell cycle. By pulsing the cytochalasin B for 30 minutes and allowing for a previously established lag time (17.5 hours) a stimulation of thymidine incorporation into DNA of proliferative epidermal and dermal cells was found in both control and stripped epidermis. Autoradiographic analysis confirmed that the stimulation was due to an increased number of basal cells accelerated from G1 to S phase. A minimal number of binucleate basal cells, 1 in 300, was observed, which suggests that the stimulated synthesis is independent of binucleate cell formation. The amount of stimulation is maximum with cytochalasin B concentration pulse between 5gamma and 30gamma/ml. The results suggest a possible link in coupling cell membrane and surface events with subsequent increased cell nuclei synthetic activity.

Mechanism of ploidy shift from diploidy to tetraploidy in MSPC-1 mouse myeloma

In order to elucidate the cytological mechanism of ploidy shift from diploidy to tetraploidy in MSPC-1 mouse myeloma, the process of cell division was observed in living cells under phase contrast microscope. It was suggested that loss of cytokinesis and subsequent formation of binucleate cells are the major causes of such a ploidy shift. Elevated frequencies of binucleate cells during the transition phase of ploidy shift from diploidy to tetraploidy also supported the above notion. The possibility of cell fusion as a cause of the ploidy change could be eliminated by analyses of marker chromosomes and incorporation pattern of [ 3H]thymidine into binuclei.