Mother Cell Wall Research Articles

Characterization of the involvement of two compensatory autolysins in mother cell lysis during sporulation of Bacillus subtilis 168.

The 30-kDa sporulation-specific peptidoglycan hydrolase CwlC of Bacillus subtilis 168 was purified and characterized. It is an N-acetylmuramoyl-L-alanine amidase (amidase) that is associated with the mother cell wall of sporulating cells, and although it is secreted, it undergoes no N-terminal processing except removal of the initial methionine. It was found that mother cells of a strain insertionally inactivated in cwlC and lytC (the major vegetative amidase gene) did not lyse at the end of sporulation. Mutants with single mutations in cwlC or lytC lysed, and so the two autolysins must have mutually compensatory roles in mother cell lysis. Active CwlC and LytC are present at the time of mother cell lysis; however, reporter gene analysis revealed that lytC transcription ceases early in sporulation, and therefore the function that LytC has in mother cell lysis is performed by material remaining from presporulation expression. Autolytic enzymes similar in molecular mass to CwlC were detected in two other Bacillus species by their cross-reactivity with anti-CwlC antiserum.

Purification and Characterization of a Vegetative Lytic Enzyme Responsible for Liberation of Daughter Cells during the Proliferation ofChlamydomonas reinhardtii

A vegetative lytic enzyme (VLE) of Chlamydomonas reinhardtii mediates digestion of the cell walls of mother cells (sporangia) to allow release of daughter cells after miotic cell division in the vegetative cell cycle. This enzyme is secreted into the culture medium concurrently with the appearance of daughter cells in synchronized cultures. Using an assay that monitors digestion of the mother cell wall, we purified VLE by ion-exchange and gel-filtration chromatography from the medium of synchronized cultures. The purified enzyme was a basic glycoprotein with an apparent molecular mass of 120 kDa on gel filtration and 130 kDa on SDS-PAGE. Thus, VLE appeared to behave as a monomer. The enzyme acted specifically on the mother cell wall and was unable to digest the cell walls derived from single vegetative cells. The enzymatic activity was inhibited by PMSF, p-APMSF, TLCK, HgCl2, iodoacetate, EGTA, EDTA and 1, 10-phenanthroline. VLE cleaved several synthetic model peptides on the carboxyl side of a Lys or Arg residue, indicating that it is a protease that acts on protein in the mother cell wall in vivo to release the daughter cells.

Mutations Affecting O-Glycosylation in Chlamydomonas reinhardtii Cause Delayed Cell Wall Degradation and Sex-Limited Sterility.

We describe a mutation, gag-1, that affects in a temperature-dependent manner a specific type of O-glycosylation in the green alga Chlamydomonas reinhardtii. In the mutant, all the major glycoproteins, in particular cell wall proteins, show a decreased apparent molecular weight in polyacrylamide gels, and their antigenicity is affected. The mutant forms multicellular aggregates (palmelloid colonies) at the restrictive temperature due to the delayed release of the daughter cells from the mother cell wall after mitosis. In addition, the mutation causes sterility by preventing sexual agglutination. In contrast to the other phenotypes, the sterility phenotype is temperature independent, and it is expressed only by cells of the plus mating type. We show that imp-8, a previously described nonagglutinating sex-limited mutation, causes the same glycosylation defect and is allelic to gag-1. Thus, expression of mt+ agglutinability appears to require the specific type of O-glycosylation that is defective in these mutants. More generally, these observations show that a sex-limited phenotype can be caused by a mutation in a gene that is not itself sex limited in its expression.

Localization of Rhodopsin by Immunofluorescence Microscope in Chlamydomonas reinhardtii

Using anti-rhodopsin antibody, an immunofluorescence method was established in Chlamydomonas reinhardtii in order to locate rhodopsin in the cell. The method showed that rhodopsin is located in the membrane near (or around) the pigmented eyespot in green algae. In synchronized cells, the location of rhodopsin changes regularly during the cell cycle. The fluorescence (F) spot moves from the anterior region toward the posterior region of the chloroplast (cp) in the light period. Following cell division, the F spots reappear in each daughter cell whether the daughter cells are released from the mother cell wall or not. The F spot is located opposite the site of the last cleavage furrow whether the cell has divided once, twice, or three times. The F spot moves back toward the anterior region from the equatorial plane after division in the dark period. In white algae eyespot-deficient mutants, rhodopsin does not depend on the presence of the eyespot. The results further showed that rhodopsin resides in the plasmalemma.

Biosorption of cadmium, copper and lead by isolated mother cell walls and whole cells of Chlorella fusca

Using a new method for the isolation of released mother cell walls of Chlorella fusca, the biosorption of cadmium, copper and lead by purified cell wall isolates and whole cell suspensions was comparatively characterized. In all cases whole cells accumulated more metal ions than isolated cell walls. Both the Langmuir and Freundlich isotherm models were suitable for describing the short-term adsorption of cadmium, copper and lead by cell walls and the cadmium and copper adsorption by whole cells. However, neither model could sufficiently explain the lead accumulation by whole cells. The feasibility of a practical use of whole cells or isolated cell walls as biosorbents is discussed.

Biosorption of cadmium, copper and lead by isolated mother cell walls and whole cells of Chlorella fusca

Biosorption of cadmium, copper and lead by isolated mother cell walls and whole cells of Chlorella fusca

Evolution of Structural Initial Cells in Apical Meristems of Plants

All the cells that compose the primary body of roots and shoots of plants derive from one or a few structural initial cells located within their apices. These cells are polyhedra, the number of whose wall faces (or sides) have increased during evolution. Mosses, algae, and leptosporangiate ferns may have initial cells with two, three or four faces, initial cells of eusporangiate ferns have five or six faces, while those of gymnosperms and angiosperms have eight faces. Seven-sided initial cells seem to be rare or absent. A scheme is proposed whereby the number of faces of an initial cell increases through an altered type of division and a suggestion is made as to how such changes may be fixed during ontogeny and, hence, how initial cell complexity becomes an aspect of plant phylogeny. In many "lower" plants, the orientation of cytokinesis in the structural initials is strictly regulated so that most, or all, of the faces of the mother cell wall pass into a daughter cell (merophyte) in a particular sequence. The same may also apply in "higher" plants, though from observational evidence this is less certain, but is nevertheless theoretically plausible. The division sequence may also be accompanied by a corresponding sequence of nuclear rotations which allows the chromosomes in the post-mitotic nucleus to retain the same positions, relative to the faces of the mother cell, that they had occupied prior to mitosis. Nuclear rotation may also facilitate conservative DNA segregation at mitosis in a structural initial, but, although there is some evidence for this, it is not an obligatory condition. Calculations are made, using three sets of conditions for division and DNA segregation, of the minimum angle of nuclear rotation necessary to accomplish one complete cycle of oriented divisions which involve all the faces of an initial (mother) cell, where the number of faces ranges from three to eight. The corresponding sequences of face involvements are also presented. Some sequences are unique to a given set of conditions. These can be compared with known sequences of divisions. In a case of a six-sided initial cell of a fern, the predicted and observed sequences correspond with semi-conservative DNA segregation and with a division rule whereby the oldest face of the mother cell wall is the one that will be donated to the next daughter merophyte. Many of the processes proposed that accompany and maintain initial cell structure and division are amenable to experimental testing.

Comparative studies of the heavy metal uptake of whole cells and different types of cell walls from Chlorella fusca

Short-term uptake of cadmium, copper and lead by whole cells, mother cell walls (mcw) and cell walls from cell homogenates (hcw) of Chlorella fusca were similar for all biosorbents: Adsorption equilibrium was reached five minutes after metal addition. Analogous, over 90% of the readily adsorbed metal ions could be desorbed by a 1 minute EDTA treatment. In all cases, short-term or long-term uptake and single ion solution or metal mixtures, whole cells showed the highest metal accumulation while hcw adsorbed more metal ions than mcw. The role of the cell wall for metal ion adsorption is discussed.

Morphogenesis of the sporoderm inPolystachia pubescens(Orchidaceae)

Abstract Pollen wall morphogenesis of Polystachia pubescens (Orchidaceae) was observed with light and transmission electron microscopy. Polystachia pubescens has pollinia which consist of isobilateral calymmate tetrads. Three sporoderm types are present within the pollinium: type 1 (forming the surface of the pollinium), with large homogeneous exine “flakes”, lacking columellae, footlayer and endexine, with a fibrous intermediate layer and a bilayered intine; type 2, which is found between tetrads within the pollinium, and whose exine is represented by small exine globules only, but otherwise is equivalent to sporoderm type 1; and type 3, found within the tetrads and solely consisting of the bi-layered intine. The whole pollinium is enveloped by a polysaccharidic film (“envelope”) which originates from tapetal and sporocyte cell walls and is formed after the tapetum has degenerated shortly before anthesis. Young microspores are separated by callose. The exine and the outer layer of the intine are formed simultaneously, while the inner layer of the intine is formed after the generative cell has become detached from the pollen wall. No primexinc could be found. The fibrous intermediate layer supporting the exine in sporoderm type 1 and type 2 derives from the “special mother cell wall”, whose callosic nature can be detected as far as the first mitosis.

Zygote formation in the homothallic green alga Chlamydomonas monoica Strehlow

Mating between cells of opposite mating type within a clonal population of Chlamydomonas monoica results in thick-walled zygotes. Zygote formation was studied in cells from continuous cultures fed with culture medium containing nitrate concentrations sufficient or limiting for growth. The factors that were considered were cell density and nitrate content of the medium. The following results were obtained: (i) Zygotes were only formed by cells that had experienced a relatively low nitrogen level that did not limit cell division. (ii) Cells were competent to mate only during a limited period of time after their release from the mother cell wall. (iii) There was a correlation between zygote yields and the number of low-nitrogen cells that were able to execute a cell division under the conditions being tested. (iv) The zygote yield per cell division was independent of the cell density. These findings indicate that the strategy used by C. monoica cells to find a mate is not dependent on random encounters. A possible explanation is that at least a large proportion of zygotes is formed by matings between cells originating from the same mother cell (siblings).

Presence and absence of the preprophase band of microtubules in moss protonemata: a clue to understanding its function?

InFunaria protonemata, preprophase bands (PPBs) of microtubules do not develop when the tip cell divides, when side branches are initiated or in intercalary regeneration divisions. We report here that PPBs do, however, develop when a tmema cell is formed. In the former cases, cell division is not coupled with an expansion of the mother cell wall at the site where the cell plate will attach. In the latter case, the mother cell wall ruptures at that site and the tmema cell elongates. This observation and the findings on presence and absence of the PPB in other cell types indicate a connection between PPB occurrence and mother cell wall expansion. They support the idea that the PPB might be involved in the local secretion of cell wall material. We extend this notion, suggesting that the microtubules of the PPB control the oriented deposition of a thin layer of cellulose microfibrils at the mother cell wall which supports the firm attachment of the cell plate when the mother cell wall expands.

Pollen Development in Actinidia deliciosa var. deliciosa: Histochemistry of the Microspore Mother Cell Walls

Comparative investigation of the development of pollen in functionally staminate (male fertile) and functionally pistillate (male sterile) flowers in Actinidia deliciosa. Development of the microspore mother cell walls

Characterization of a sperm lysin of Volvox carteri

A cell-wall degrading enzyme has been isolated from mature sperm packets of the green flagellate Volvox carteri (Poona strain). This sperm lysin (S-lysin) is a Ca2+-dependent protease of 34 kDa with an essential serine group in its active centre. Neither SH group-blocking reagents nor transition metal chelators inhibit its action. S-lysin degrades the hydroxyproline-rich glycoprotein structures of the cell walls of sheath cells and gonidia (eggs) of vegetative and sexual spheroids in a characteristic manner. In asexual spheroids the somatic envelope is totally disintegrated, whereas in sexual spheroids pores are formed by local lysis at sites of adjacent eggs. Although S-lysin is very similar to the G-lysin of the closely related Chlamydomonads, it is species specific and does not attack the mother or daughter cell walls of Chlamydomonas reinhardtii. S-lysin resembles the aerosin of animal sperm cells in some aspects of its action.

Haustorial mother cell development by Uromyces vignae on collodion membranes

The development of infection structures by the rust fungus Uromyces vignae was observed on oil-containing collodion membranes. About 40% of infection hyphae formed a haustorial mother cell, but this structure commonly senesced and died more rapidly than the infection hypha to which it was attached. These data suggest that the continued development of the haustorial mother cell requires some component normally provided by the host plant. Before they died, many haustorial mother cells apparently formed the thickened region of the wall which normally is traversed by the penetration peg during haustorium formation. Such a peg was observed in the centre of up to 40% of these thickened regions. However, no pegs protruded beyond the haustorial mother cell far enough to be called a haustorial neck. The thickened region of the haustorial mother cell wall could be differentiated from the rest of the wall by its lack of fluorescence under ultraviolet irradiation when mounted in Calcofluor or SITS (4-acetomido-4′-iso-thiocyanatostilbene-2,2′-disulphonic acid). Treatment with alkali, acid, chloroform–methanol, protease, and laminarinase did not affect this differential fluorescence, and the haustorial mother cell wall stained uniformly for proteins, carbohydrates, and chitin. Since Calcofluor normally binds to chitin, these data suggest that the thickened region of the haustorial mother cell wall may physically exclude the dye or may contain potential binding sites that are masked by other wall components.

Cell plate development and delayed formation of the pectic middle lamella in root meristems

The first stages of cell wall formation were followed in the root meristems of maize and French bean. Most of the primary wall components (hemicellulose, cellulose and highly methylated pectins) were laid down simultaneously along the cell plate. During young cell wall maturation within the meristem itself, significant topochemical alterations, coupled with the addition of new polysaccharides, produced complete redistribution of wall material leading to the progressive appearance of a proper middle lamella. Thus the formation of a pectic middle lamella does not precede the deposition of primary walls. It is delayed until the new partition joins to the mother cell wall.

Zellteilung und Sporulation als wichtige Unterscheidungsmerkmale bei Grünalgen (Chlorophyta)

Summary The cell division is an important character in the filamentous green algae, mainly in the unicellular forms where the cell division is the only modus of reproduction and where with they differ from the unicellular coccoid algae reproducing by sporulation. Sometimes it is difficult to distinguish between both processes if only two autospores in coccoid algae are produced. The cell division is a process where one cell divides into two equal parts (daughter cells) by mitosis and following cytokinesis. Both daughter cells using the mother cell wall grow up and divide again. In contrary the sporulation is a process where the cell mostly divides into few or many daughter protoplasts (precursors of spores), while the mother cell wall is forming the sporangium. In multicellular algae the cell division serves to the growing, development and differentiation of the multicellular organism, while the sporulation only to the reproduction. The cell division in green is sometimes algae also a modus of reproduction: As schizotomy (bipartition) in naked Phytomonadina and as cytotomy (vegetative cell division) in the unicellular algae of Stichococcus- or Closterium-type. With regard to the characters it will be relatively easy to distinguish between cell division and sporulation. Only an example where both terms were taken by mistake are pseudofilaments (Cylindrocapsa, Radiofilum) or diads and tetrads (Chlorosarcinales) with modified sporulations. A survey of all differences between cell division and sporulation is enclosed.

Taxonomic approch to the micro alga participated in the yellowish green water bloom of Sagami Reservoir, Central Japan

In early summer of 1987 the micro alga occured in large quantities as plankton in the eutrophicated Sagami Reservoir of Kanagawa, Japan. The composition of planktonic comunity at that time differed distinctly from that of late years. It consisted almost of the mono-alga that, by its biomass, brough about the yellowish green water bloom during the periodJune to July. In the case of its mass occurence, thenumber of cells per 1 ml was about 2 million. Thealga was studied in the living stage from the various viewpoints of taxonomy and defined by the following features.Colonies 4-celled to about 32 celled, with cellsplaced at the ends of remnants or strands thatwere formed by the rupture and gelatinization ofthe mother cell wall. Mucilage almost absent, butin the case of presence badly visible. Adult cells spherical 4.0-6.5μm in diameter, chloroplastcup-shaped with pyrenoid. Asexual reproductionthrough autospores. Autospores spherical-oval to spherical, formed 2 or 4.According to each kind of the observed results, it is satisfactory to consider this micro alga asDictyosphaerium pulchellum Wood var. minutum DEFL.1926It appears to be the first report, in Japan, that thegenus Dictyosphaerium perticipated in the yellowishgreen water bloom in the eutrophic waters.

Mechanisms of Pollen Aggregation into Pollinia inEpidendrum Ibaguense(Orchidaceae)

Abstract In Epidendrum ibaguense, pollen is aggregated into pollinia as united masses. The present study demonstrates that the mechanism of pollen aggregation is built into the various stages of pollen development. It is suggested that the pollen are held together due to a combined effect of the following features: (1) the remains of the pollen mother cell wall, (2) the fibrillar material present within the callosic cell wall during meiosis and tetrad formation, (3) the persistence of some plasmodesmata from the PMC stage of pollen development, (4) incomplete cell wall formation within tetrads, and (5) little size increase of developing microspores

Mitochondrial number and form change during autospore formation in Chlorococcum infusionum (Schrank) Meneghini (Chlorococcales, Chlorophyta)

Abstract Three dimensional form changes of mitochondria during the autospore formation of Chlorococcum infusionum are followed with the electron microscope. In the youngest cells, five ovoid mitochondria are seen. In mature cells, nuclei divide successively three or four times without being accompanied by cell division. During this period, mitochondria multiply to about 20. Shortly before septum formation, mitochondria fuse with each other to form a reticular and branched mitochondrion. Later, the reticular mitochondrion is divided by growing septa, thus being distributed in the autospore. In cells liberated from mother cell walls, the mitochondrion is fragmented into several ovoid pieces. These mitochondrial form changes are discussed in comparison with those reported in other organisms.

Cytochemical studies on Puccinia graminis f. sp. tritici in a compatible wheat host. II. Haustorium mother cell walls at the host cell penetration site, haustorial walls, and the extrahaustorial matrix

Various cytochemical tests on the wheat stem rust fungus were used to determine differences in components of the walls of the haustorium mother cell at the host cell penetration site and the haustorial neck and body and to describe some of the chemical properties of the extrahaustorial matrix. There were two transition zones with respect to wall composition. The first was at the host cell penetration site; chitin, present in haustorium mother cell walls, was not detected in haustorial neck walls. The second transition zone was at the neck ring; compared with walls of the proximal neck region, those distal to the neck ring contained more protein and lost much of their periodate – thiocarbohydrazide – silver proteinate reactive material and all concanavalin A binding material after treatment with protease. The two wall layers of the distal part of the haustorial neck were continuous with those of the haustorium; the wall layers of young haustorial bodies shared their staining properties and lectin affinities with those of the distal part of the haustorial necks, reflecting their common origin. As the haustoria matured, their body walls bound wheat germ lectin, but the neck walls did not. Tests indicated that polysaccharide and glycoprotein were present in the extrahaustorial matrix.