Multicellular Bodies Research Articles

Spatially Regulated Translation in Embryos: Asymmetric Expression of Maternal Wnt-11 along the Dorsal–Ventral Axis in Xenopus

Transition from symmetry to asymmetry is a central theme in cell and developmental biology. In Xenopus embryos, dorsal–ventral asymmetry is initiated by a microtubule-dependent cytoplasmic rotation during the first cell cycle after fertilization. Here we show that the cytoplasmic rotation initiates differential cytoplasmic polyadenylation of maternal Xwnt-11 RNA, encoding a member of the Wnt family of cell–cell signaling factors. Translational regulation of Xwnt-11 mRNA along the dorsal–ventral axis results in asymmetric accumulation of Xwnt-11 protein. These results demonstrate spatially regulated translation of a maternal cell-signaling factor along the vertebrate dorsal–ventral axis and represent a novel mechanism for Wnt gene regulation. Spatial regulation of maternal RNA translation, which has been established in invertebrates, appears to be an evolutionarily conserved mechanism in the generation of intracellular asymmetry and the consequential formation of the multicellular body pattern.

P3C101 - Effects of high-level lead exposure on NK cell and T-lymphocyte functions and some important cytokine levels in man

We have shown previously that riboflavin is stored in chloragosomes of chloragocyte-derived earthworm eleocytes what may have an adaptive value for worms vulnerable to soil-derived pathogen invasion. Thus, it is important to determine whether riboflavin stores are also present in earthworm species with low eleocyte counts, especially in the chloragocytes of their chloragogen tissue that surrounds the coelomic site of the intestine, and find out its putative roles in earthworm immunity. Experiments were performed on adult worms from 6 species. Freely floating coelomocytes (consisting of amoebocytes plus species-specific numbers of eleocytes) were extruded by mild electric shock and then chloragocytes from the same anaesthetized worm were mechanically detached into buffer. Both cell suspensions were analyzed by spectrofluorometry for riboflavin content. It turned out that riboflavin is stored in species-specific quantities in all investigated species. Riboflavin storage predominates in free coelomocytes of eleocyte-rich species (Eisenia andrei, Dendrobaena veneta, Allolobophora chlorotica) while in chloragocytes of species with few eleocytes (Lumbricus terrestris, L. rubellus, and Aporrectodea caliginosa). Upon a massive microbial impact, the coelomocytes (both amoebocytes and eleocytes) are involved in the formation of multicellular bodies encapsulating soil-derived pathogens, what is connected with enhanced coelomocyte mobility. Thus the second aim of the present investigation was to check if riboflavin can participate in coelomocyte accumulations. Tests performed in a 48-well chemotaxis chamber revealed that riboflavin behave as chemoattractant for coelomocytes of all investigated earthworm species, which may be one of mechanisms underpinning its immunomodulatory functions.

Cellular ‘elementary organisms’ in vitro. The early vision of Gottlieb Haberlandt and its realization

The botanist Gottlieb Haberlandt was the first who in 1898 (published in 1902) tried the systematic culture in vitro of single cells. His purpose was to study the mutual influences of cells as the last ‘living units’ within the multicellular body. Haberlandt visualized the theoretical potential of the culture approach in experimental plant morphology and physiology and nearly half a century was to elapse before his far‐reaching ideas were realized. The history of cell and tissue culture is traced from the first concepts and origins in experimental embryology (1858/59) to its final verification almost 100 years later. The paper reminds of essential steps, theoretical backgrounds, accidental and planned discoveries and methodological approaches, and attempts to present all sources. The more or less known reviews of White (1931, 1936 and 1946), Fiedler (1938/39), Stapp (1947), Kandler (1948) and Street (1959) are summarized, and the mutual influence of plant and animal tissue culture on each other is discussed. Previous retrospective articles on the particular role of Haberlandt, namely those of Gautheret (1942) and Krikorian and Berquam (1969), are included in a general assessment of physiological anatomy in memory of the 50th anniversary of this great botanist's death.

Culture and development of electrically fused protoplasts from red marine algae, Porphyra yezoensis and P. suborbiculata

The electrically fused products of protoplasts from a wild type and a mutant strain of Porphyra yezoensis were cultured in a modified agar medium, named “soft agarose two-layer medium” for 40 days, and then transferred and cultured subsequently in a liquid medium. In the soft agarose two-layer medium, fused products could be distinguished easily from unfused protoplasts. The survival rate of fused products in the soft agarose two-layer medium was considerably higher than that of those in the liquid medium. However, growth rate of multi-cellular bodies which developed from fused protoplasts was higher when protoplasts were moved from the two-layer medium to liquid medium. The fused products repeated cell divisions and formed irregular-shaped multi-cellular bodies. After 2 months of culture, a large number of cells in these cellular bodies differentiated into monospores which then germinated and grew to young thalli. Eventually, four out of approximately 180 fused protoplasts developed to young thalli. Morphologically hybrid-like thalli were obtained in an electrofusion experiment with protoplasts from Porphyra suborbiculata and a mutant strain of P. yezoensis, which suggested that genetic recombination would be possible between these two species.

Pleoanamorphic life cycle of Exophiala (Wangiella) dermatitidis.

The anamorph life cycle of the black yeast Exophiala (Wangiella) dermatitidis is described. The fungus is dimorphic, yeast cells being the prevalent form of propagation. The fungus is strongly hydrophilic, probably completing its anamorph life cycle in submersion. Adaptation to dry conditions is slow. Types of conidiogenesis comprise annellidic, phialidic and sympodial reproduction, in addition to isotropic development. Phialoconidia fail to germinate under the conditions tested, and thus may have a function other than dispersal. Sterile, multicellular bodies resembling a Capronia teleomorph are described.

Micronomads of the Mediterranean sea

Abstract The Structural Heterogeneity of Plants with a Thallus. Plants that evolved in aquatic environments developed a thallus, that is a multicellular body without structures deputed to the mass transportation of water along great distances. The structural organisations of thalli shows a number of different solution to reach the coordination necessary to the expression of differentiation in the multicellular thalli. Some of these structures are comparatively esamined, pointing out their peculiarities. The diversity observed among plants evolved in aquatic environments is expressed not only by the taxa that can be recognized, but also by a great number of solutions developed to express the differentiation of parts in a complex multicellular body.

Biochemical Aspects of Cytokinesis

Publisher Summary Cell division is an indispensable process for living organisms. The cell has to pass its genetic information on to its offspring, and at the same time, it has to increase its own number and type in order to proliferate and make up a multicellular body. The former is carried out by nuclear division and the latter, by cytokinesis. This chapter discusses cytokinesis in animal cells, which is considered a typical and important example of cell motility in eukaryotic cells. Cytokinesis is basically the same in all animal cells, from primitive, ciliated protozoa to human cells. Cytokinesis in animal cells generally takes place by furrowing at the equatorial cell cortex. The contractile ring is the force-generating structure for cytokinesis of animal cells through actin–myosin interaction. In the case of sea urchin or sand dollar eggs, the signal, commonly called cleavage stimulus, is mediated by asters to form the cleavage furrow, which is given to the cell cortex after anaphase. Changes in Ca concentration, polyamines, and myosin are regarded as candidates for the signal. The actin-modulating proteins are highly relevant to the formation of the contractile ring in any of the possible processes.

Comparative morphology of the leaf epidermis in the genera Codonanthe (Martius) Hanstein and Nematanthus Schrader (Gesneriaceae)*

The leaf epidermis of 14 species ofCodonanthe and 10 species of Nematanthus has been examined. Species of Codonanthe section Codonanthe are geographically restricted to south-eastern Brazil, and are diploid. They possess multicellular-uniseriate nonglandular trichomes, glandular trichomes with a four-celled head and a short body, anisocytic stomata and lack extrafloral nectaries. Species of Codonanthe section Spathuliformae and Codonanthe subgenus Codonanthella are distributed from southern Mexico through Central America to north-western South America and are tetraploid. They possess unicellular non-glandular trichomes (except C. caribaea), glandular trichomes with a two-celled head (except C. caribaea) and a short body, anisocytic stomata and extrafloral nectaries (except C. caribaea). All Nematanthus species are distributed in south-eastern Brazil and are diploid (N=8). Six species of Nematanthus consistently have multicellular-uniseriate nonglandular trichomes, glandular trichomes with a four-celled head and a short (unicellular) or long (multicellular) body, anisocytic stomata and lack extrafloral nectaries. Four species of Nematanthus have multicellular-uniseriate non-glandular trichomes, glandular trichomes with a head of more than four cells and a short body, anisocytic and helicocytic stomata and lack extrafloral nectaries.

Genetic Analysis of the Slug Stage of Dictyostelium discoideum

During the course of development, cells of Dictyostelium discoideum are able to produce a multicellular body (a ‘slug’) which is capable of movement over the substratum. This phase, which is induced by production of ammonia by the starving cells, may last for hours or days depending on environmental stimuli. In order to probe the regulatory system controlling formation and duration of the slug phase, mutants were isolated that remained in the slug phase for an extended period. Thirty-two such ‘slugger’ mutants were analysed by parasexual genetic techniques and placed into 10 complementation groups (slgA-slgJ). The linkage groups bearing representatives of these complementation groups were determined by segregation of diploids formed between mutants and tester strains. Phenotypic studies of mutants indicated that members of slgD, slgE and slgG were over-sensitive to the ammonia slug-inducing stimulus.

Evolutionary and Functional Relationships of Homologous Physiological Mechanisms

tween simple prokaryotic organisms like bacteria and complex eukaryotic organisms like higher animals and plants is that the latter have multicellular bodies composed of various types of specialized tissues and cells. Even very similar tissues such as skeletal and cardiac muscle can contain different forms of a number of proteins. The genes that code for these proteins are present in all cells of the body, though normally they are expressed only in certain ones. Often these proteins are markedly similar in amino acid sequence and three-dimensional structure to other proteins with similar functions. We believe that such similarity indicates an evolutionary relationship among these proteins: They originated by duplication of a gene in an ancestral species, perhaps hundreds of millions of

Creative functions of instability and oscillations in metabolic systems.

This chapter discusses the creative functions of instability and oscillations in metabolic systems. The aim of the biological regulatory mechanisms is to stabilize the important metabolic parameters in living organisms. Recognition of allosteric properties of regulatory enzymes has stimulated discussion of cell regulatory mechanisms in relation to cell homeostasis. The chapter focuses on the creative force of instability in regard to homeostasis and homogeneity as a new approach to the understanding of cellular regulation. Homeostasis in time and homogeneity in space constitute the classic frame work for a presentation of function and structure. Although exogenous fluctuations are filtered out by living systems, autonomous oscillations as well as dynamic in-homogeneity of matter could be observed in cells and multicellular bodies. It means that the organisms create their own timing and spacing, which might couple to external signals. The theoretical and experimental data reviewed allow concluding that the instability of metabolic systems may be important for the temporal and spatial organization of living matter.

Certain observations on Scytonema stuposum (Kuetz.) Born. (Cyanophyta, Nostocales)

Some interesting cultural observations on Scytonema stuposum (Kuetz.) Born., were recorded. It was observed that frequently one or more terminal cells of a branch get cut off but they still remain attached over the sheath of the mother filament. Even in this condition such structures continue their growth and may become a multicellular body. Later, such a structure gets detached from the mother filament and serve as a hormogonium.

Membrane proteins in human erythrocytes during cell fusion induced by oleoylglycerol.

1. The fusion of human erythrocytes into multicellular bodies that is induced by microdroplets of oleoylglycerol was investigated by optical and electron microscopy, and by gel electrophoresis of membrane proteins. 2. At the highest concentrations of oleoylglycerol and Ca(2+) used, at least 80% of the cells fused after 30min at 37 degrees C and only about 5% of the cells had completely lysed; the shapes of fused multicellular bodies were usually retained in ;ghosts' prepared by hypo-osmotic lysis. 3. The rate of cell fusion was related to the concentration of Ca(2+), although some cells fused when no exogenous Ca(2+) was present. 4. Interactions of microdroplets of oleoylglycerol with the cells led to abnormalities in the structural appearance of the erythrocyte membrane; subsequent membrane fusion occurred, at least in some instances, at the sites of the microdroplets. 5. The intramembranous particles on the P-fracture face of the treated cells were more randomly distributed, but not significantly increased in number by comparison with the control cells. 6. Gel electrophoresis of the proteins of ;ghosts' prepared from fused human erythrocytes showed a production of material of very high molecular weight, the development of a new component in the band-3 region, an increased staining of bands 4.3 and 4.5, and a new component moving slightly faster than band 6. 7. Bands 2.1-2.3 were altered, band 3 was decreased and band 4.1 was lost. 8. Most, but not all, of the changes in the membrane proteins appeared to result from the entry of Ca(2+) into the cell. 9. 1-Chloro-4-phenyl-3-l-toluene-p-sulphonamidobutan-2-one partially inhibited both cell fusion and the associated decrease in band-3 protein. 10. The possibility that proteolytic degradation of membrane proteins may be involved in cell fusion induced by oleoylglycerol is considered, and some implications of this possibility are discussed.

Production of Plants from Anthers ofSolanum NigrumCulturedin Vitro

SUMMARYAnthers of Solanum nigrum L. (2 n = 72) were cultured in modified Murashige and Skoog's medium supplemented with NAA, 2,4-D and kinetin (« callus-inducing medium »). Calluses emerging out of the anther slits were later transferred to a differentiation medium with low or no auxins until plantlets began to develop.Out of 98 plants derived from the calluses, about half were haploid and the remainders were diploid, triploid, or aneuploid.In the locule of the anthers cultured for a few weeks, various stages of microspores changing to multicellular bodies were observed, indicating that the calluses might be of microspore origin.In the callus-inducing medium some of the parenchyma cells of callus tissue changed to multicellular bodies or multinucleate giant cells. In the callus sub-cultured for a few months on the differentiation medium, concentric tissues, tracheid-like structures, and shoot primordia developed.

Cell dissociation: univalent antibodies as a possible alternative to proteolytic enzymes.

Univalent antibody fragments directed against special membrane antigens dissociate multicellular bodies of the cellular slime mold Dictyostelium discoideum completely into single cells. This provides a gentle method for cell dissociation and demonstrates that a nonenzyme protein can disintegrate a tissue

The inhibition of cell aggregation by a pure serum protein

ABSTRACT The aggregation of isolated cells into coherent multicellular bodies is widely thought to be due mainly if not entirely to the adhesiveness of the cells for one another, according to Moscona (1961a, b), Curtis (1962) and Steinberg (1962a) amongst others. In consequence the aggregation of cells from dispersed (disaggregated) tissues has been widely used as a test for the degree of adhesiveness shown by the cells, and conditions affecting aggregation have been interpreted as affecting cell adhesion. Using this type of test Moscona (1961a, b) found that embryonic chick cells would not aggregate at temperatures below 14° C. It was also discovered that aggregation was inhibited at 37° C. by puromycin and actinomycin D (Moscona & Moscona, 1963), by glucosamine-HCl (Garber, 1963), and by chloramphenicol (Nakanishi et al., 1963). Moscona concluded from the failure of aggregation at low temperatures that the metabolic synthesis of an adhesive substance was being prevented under such conditions and this interpretation was reinforced by the evidence of chemical inhibition of aggregation. Moscona (1962) suggested that the adhesive substance was responsible for producing cell to cell adhesion. In all these experiments cells were aggregated in media containing serum, usually horse serum.

<i>Microccus gluamicus</i> の細胞学的研究

It was reported in a previous paper that the elongated, enlarged and even branched form of Micrococcus glutamicus was observed in the synthetic medium containing Na-citrate or Na-malate. As the result of the investigations on substances having the effect like that of Na-citrate or Na-malate, following informations were obtained obviously.1. Among various salts of citrate, ammonium and potassium salts showed the similar effect to that of Na-salt on the morphological change.2. Na-oxalate also has a strong elongating and branching effect.3. Generally, amino acids promote the cell growth of M. glutamicus. The large quantities of L-alanine and L-cystein, however, inhibit its growth. The elongated and enlarged cells were formed by the addition of 50mg./ml. of L-cystein.4. High multicellular and elongated bodies were formed in a medium containing the low level of penicillin. Such multicellular bodies, however, were never formed in the penicillinmedia if the biotin content was increased to 100γ/l. From this fact, it seems that penicillin strongly inhibits the separation of the daughter cells rather than the cytoplasmic division.5. The multicellular bodies never formed in a medium containing streptomycin. But a vacuole-like structure in each cell was formed in the concentration of 0.4-0.8γ/ml. of streptomycin.6. Remarkable multicellular bodies were formed in the concentration of 0.2-0.8γ/ml. of mitomycin-C. In these cases, the length of cell is 10μ or over occassionally. One or both ends of these cells were swollen and become so-called club-shape.

I.—Studies in Floral Morphology. II. The Staminal Zygomorphy of Couroupita guianensis, Aubl.

In a former memoir published in these Transactions (20) the developmental study of floral characters has been reopened. It has there been shown that by this study, which for long has received little attention, the investigator, aided by modern technical methods, may gain a fuller understanding of the value of the characters by which his judgment in systematic matters is guided. The subject then dealt with was the initiation of staminal zygomorphy in certain dicotyledonous plants. It was there shown that in the history of a stamen from its initiation as a primordium until its anther is dehisced and its pollen shed there are three more or less distinct consecutive phases. In the first, or phase of initiation, the stamen-primordium is defined. From this primordium an undifferentiated multicellular body arises by rapid cell-division. In the second phase this body undergoes differentiation into the component parts of a stamen ; an anther and frequently a filament and connective are defined, and their cellular construction is completed. In the third and final phase the stamen is extended and functionates forthwith as a disseminator of pollen-grains. In this phase the extensible and elastic walls of the cells of the filament are distended by internal hydraulic pressure, and the anther-walls are dried and finally rupture by inequalities in their rate of shrinkage and by the agency of fibrous devices. These steps form the prelude to the actual functionating of the stamen, and since the final enlargement of the stamen-filament is due to water-pressure, this phase is known as the phase of extension.