Teilungsverhalten der Chromatophoren in bezug auf die Mitose während des Lebenszyklus vonDiatoma hiemale var.mesodon,II

The studies of the cell cycle ofDiatoma hiemale var.mesodon have been continued on a population during the whole vegetative period (August–October 1976). The lapse of time between the maxima of the chromatophore division and the mitosis is 8 hours in the exponentional and stationary phase of growth of the population; during the decline and decay of the population it is shortening to 2–4 hours. The sequence of phases is maintained, but the stage of praemitotic stagnation is shortened to a minimum. During the stage of the chromatophore division a relationship was found between time lapse and chromatophore number per cell. The cell cycle (asexual life cycle) ofDiatoma hiemale var.mesodon has been schematically illustrated during optimal development and its different stages are discussed.

Teil I:Ettl & Bezina (1975).     

Zellteilung und Bildung von Innenschalen beiHantzschia amphioxys undAchnanthes coarctata

Before cytokinesis, the identically constructed chromatophores ofHantzschia amphioxys andAchnanthes coarctata are transformed into less effigurated bodies. In normal cytokinesis, the course of mitosis, chromatophore division, and cleavage furrowing are exactly synchronized. The division of the chromatophore appears as a passive process, i.e. intersection by the cleavage furrow. In inequal cell divisions before the formation of inner valves cytokinesis can take place without chromatophore division. Once chromatophore division without mitosis and cytokinesis was observed. InHantzschia there are three types of inner valve formation, inAchnanthes coarctata only two. The inner valves develop under unfavorable growth conditions, the cells possessing them, however, are not resting spores as in some other diatoms. InHantzschia, auxospore formation is suppressed under the cultural conditions used, the cells multiply intensely without diminution.

     

Heteropolarity in unicellular cyanobacteria: structure and development ofCyanocystis violacea

Cyanocystis violacea isolated from a marine rock sample conforms with the diagnosis ofDermocarpa violacea Crouan in all significant characteristics. The distinct heteropolarity of the cells and simultaneous cell divisions, are stable characters in culture. Development and growth of cells, simultaneous cell division and nanocyte formation have been documented by single-cell slide cultures and fine structural studies. The reddish violet color of the cytoplasm is due to the abundance of phycoerythrin.This paper is dedicated to Prof. DrLothar Geitler, whose monumental contribution to the knowledge of blue-green algae will remain the basis for future studies on these organisms for many years to come. One of us (EIF) was fortunate enough to have had Prof.Geitler as his major professor. All of us consider Prof.Geitler our teacher.     

Teilungsverhalten der Chromatophoren in bezug auf die Mitose während des Lebenszyklus vonDiatoma hiemale var.mesodon

The vegetative life cycle ofDiatoma hiemale var.mesodon (Ehr.)Grun. living in a spring has been studied under natural conditions. In the beginning the cells have a constant number of 8 chromatophores which are divided into 16 during cell growth. Chloroplast division is finished before nuclear division starts. The young daughter cells have again 8 chromatophores. In the course of cell division a plastic remodelling of the chromatophores and a simplifying of their shape occurs. Besides single cells also populations have been studied to follow the temporal progress of chromatophore division, mitosis and cell growth. The results are evaluated by indices and demonstrated by a diagram. The maximum of chromatophore divisions preceds the maximum of mitoses by several hours, while the cell growth is in correlation with the chromatophore division. Minima of the other parameters were found before mitosis is starting and after it is finished. Our results are discussed with regard to the semiautonomy of the plastids. From the morphological point of view this concept is supported by the mode of division and by the anticipation of the chromatophore division. The number of chromatophores at the beginning (8) and at the end (16) of the life cycle is constant. The life cycle is classified into stages of cell growth, chromatophore division, stagnation, mitosis and differentiation of the daughter cells.     

Über die Abgrenzung derChlorosarcinales von denChlorococcales

It is proposed to use amongst other characters the type of cell division in order to delimit theChlorosarcinales from theChlorococcales. A definition of the two processes of division occuring in these orders is given. It differs from that of other authors. In theChlorosarcinales only those genera should be assembled in which vegetative daughter cells arise by bipartition followed by firm association of the wall between the daughter cells with that of the mother cell. In contrast, autospores, the vegetative daughter cells of a number ofChlorococcales, develop by multiple division, their cell walls are formed all around the protoplasts and are free from that of the mother cell. The chlorococcalean generaTrebouxia andDictyochloropsis incorporate species which multiply by zoo-, aplano- and autospores as well as others having no autospores. Autospores possibly have arisen more than once during evolution.

     

Über die Phycobionten der SektionCystophora vonChaenotheca,insbesondereDictyochloropsis splendida undTrebouxia simplex,spec. nova

Chaenotheca brunneola is lichenized withDictyochloropsis splendida. Until now this member of theChlorococcales has been observed only twice and free-living. It reproduces by motionless daughter cells in the lichen thallus, but mainly by zoospores in the free-living state and under favourable conditions. Zoospore development has not been observed before and apparently depends on storage of starch which is repressed in the lichenized state. During zoospore activity this storage material is consumed. Zoospores possess two flagella which are inserted rather far apart from each other, one pulsating vacuole and a cup-shaped, not latticed chloroplast.Chaenotheca phaeocephala var.alpina, Ch. melanophaea andCh. chrysocephala are lichenized withTrebouxia. The phycobiont ofCh. chrysocephala, Trebouxia simplex, sp. n., differs from other sibs of the genus by the relative small size of the cells, the less marked differentiation of the chloroplast and certain details of cell division.

     

Die Zweiteiligkeit der Chromatophoren bei Cryptomonaden

In theChrysophyceae as well as in different species ofCryptomonas bilobed chromatophores are present. These chromatophores consist of two large parietal lobes closed to the lateral sides of the cell and joined by a narrow bridge on its dorsal part. A survey of all species with a single bilobed chromatophore is given. Besides, also species with two separate chromatophores have been found. The presence of several chromatophores inCryptomonas cells is doubtful. The morphology of the chromatophores has to be taken into consideration in the taxonomy ofCryptomonas.

     

Behavior of leucoplast nucleoids in the epidermal cell of onion (Allium cepa) bulb

Summary The behavior of nucleoids during the leucoplast division cycle in the epidermis of onion (Allium cepa) bulbs was investigated using DNA-specific fluorochrome 4'6-diamidino-2-phenylindole (DAPI) staining. The leucoplast was morphologically amoeboid and continuously changed its shape. A dumbbell-shaped leucoplast divided into two spherical daughter ones by constriction in the middle region of the body. Leucoplasts contained 4–10 mostly spherical, oval, partly rodand dumbbell-shaped nucleoids which were dispersed within the bodies. The proportion of one DNA molecule of a T4 phage particle to the small leucoplast nucleoid in the grain density of negative film was 1 to 0.91. Comparison of the present result and another groups' biochemical results suggested that a small leucoplast nucleoid contains one DNA molecule. The dumbbell-shaped leucoplast probably before division contained about twice as many nucleoids as the spherical leucoplast after division, and each half of the dumbbell contained about half the number of nucleoids. Nucleoids increased in number with growth of the leucoplast. The behavior of nucleoids during the leucoplast division cycle in onion bulbs was basically similar to that during the chloroplast division cycle in higher plants and green algae, which was previously reported (Kuroiwa et al. 1981 b).     

Über Plastidenstapel beiBotrydiopsis alpina sowie Anlage und Vermehrung der Stigmen bei dieser undHeterococcus (Xanthophyceae)

Under certain conditions inBotrydiopsis alpina stacks of chloroplasts are formed. They consist of up to 8 elements. In contrast to what is known from other algae in zoosporangia of this species and ofHeterococcus caespitosus, stigmata are formed in early developmental stages. They are reproduced together with the chloroplasts, in which they occupy a position at the edge and near the existing or future incision. At the side of the old stigma a new one is formed, and partitioning of the chloroplast between these two leads to their distribution to the daughter chloroplasts. Young daughter cells in the zoosporangia ofBotrydiopsis alpina contain one chloroplast which undergoes a last unequal division giving rise to one astigmate and usually somewhat smaller and to one stigmate chloroplast. In both species the capacity for locomotion may be suppressed, the presumptive zoospores thereby becoming aplanospores. Autospores in the proper sense were not observed. Their development quite generally is different from that of aplanospores (and zoospores), and both types of spores should be distinguished.

Herrn Professor Dr.Lothar Geitler zum 80. Geburtstag in Verehrung gewidmet.     

Development of the zoosporangia ofSynchytrium endobioticum,the causal agent of potato wart disease

Summary An ultrastructural study of zoosporangium development ofSynchytrium, endobioticum (Schilb.) Perc. is presented. Emphasis is placed on the location of the parasitic fungal thallus in the potato host cell, on the specific location of organelles in relation to the developing zoosporangial wall, and on the host cell reaction to the fungal infection. The cytoplasmic organization of the individual sporangia after division of the zoosporangium into a sorus of sporangia is characterized by numerous similarly sized nuclei, well developed dictyosomes, and the presence of many lipid bodies of variable size. Cytoplasmic microtubules are observed to flare out from the functional kinetosome both before and after zoospore cleavage.The ultrastructural details of zoosporangium development are used to revaluate the life cycle ofS. endobioticum as described from light microscopic observations made early in the century (Curtis 1921;Köhler 1923, 1932;Percival 1910).     

Taxonomic status of the species of the green algal genusNeochloris

Komárek has recently reviewed the various species assigned to the green algal genusNeochloris Starr (Chlorococcales, Chlorococcaceae) and removed those with uninucleate vegetative cells to a new genus,Ettlia. Watanabe & Floyd, unaware ofKomárek's work, also reviewed the species ofNeochloris and distributed them among three genera—Neochloris, Chlorococcopsis gen. nov., andParietochloris gen. nov.—on the basis of details of the covering of the zoospore and the arrangement of the basal bodies of the flagellar apparatus. This paper reconciles these two treatments and makes additional recommendations at the ranks of genus, family, order, and class.     

Ultrastructure of cell division and reproductive differentiation of male plants in theFlorideophyceae (Rhodophyta). Mitosis inDasya baillouviana

Summary Mitosis in the marine red algaDasya baillouviana (Ceramiales, Florideophyceae) was observed with the electron microscope. Most details of the process are quite similar to those observed in the other macroscopic red algae studied to date. However, some minor variations were noted. At late prophase a very small nuclear envelope protrusion (NEP) is formed at each division pole subjacent to the nucleus associated organelle known as the polar ring (PR) and 2–3 cisternae of perinuclear endoplasmic reticulum (PER) are commonly present during metaphase-anaphase. In contrast, in the other florideophycean algae where mitosis has been reported, a prominent NEP is present at late prophase (McDonald personal communication,Scott et al. 1980) and only a single cisterna of PER is observed. Additionally, during mid-late interphase and in mitotically-quiescent cells ofDasya, a single cisterna of smooth-surfaced ER is always juxtaposed with each PR. The possible significance of PER in theFlorideophyceae and other multinucleate organisms is discussed as well as the likely functions of spindle-associated smooth ER. It is suggested that ultrastructural features of mitosis should be useful as criteria to aid in the interpretation of the phylogeny of red algae.     

Etude des migrations verticales journalières du phytoplancton à l'aide d'enceintes placées dans un Rang peu profond

Two enclosures without a bottom were placed in a shallow non-stratified pond. One of these enclosures (B) had a transparent plastic wall and was open at the top. The second enclosure (N) was painted in black and covered over. The vertical distribution and daily migration of Ceratium hirundinella, Trachelomonas spp., Gomphosphaeria naegeliana and Aphanizomenon flos-aquae were studied. Investigations were carried out during a 24 h period both in the pond and inside the two enclosures. Vertical migration was shown by the four algae, even within the water column N. Differences between the behaviour patterns of the different algae are described.

     

Bewegungs- und Teilungsverhalten der Chromatophoren vonEunotia pectinalis var.polyplastidica und andererEunotia-Arten bei der Zellteilung

Summary The correlation between the start of chromatophore division and cell division is very different in various species ofEunotia. In some species the chromatophore division occurs before, in others after cell division. Eunotia pectinalis var.polyplastidica, with eight chromatophores per cell, represents an extreme type of behaviour in so far as two of the four plastids in each daughter cell prior to their division are shifted to the new hypovalve while the other two rest in situ. There occur two patterns of distribution of the four plastids, and that in the ratio 11, whereas the theoretically possible third pattern is never realized. The cause of that phenomenon is discussed. The division of the four plastids, in the meantime grown to full size, is performed not before they have reached their definitive equilibrium position at the epivalve or, respectively, at the hypovalve in twos. InEunotia pectinalis var.polyplastidica, by its mode of chromatophore division, the constant dissymmetric (right-left-handed) arrangement of the growing chromatophores, established inEunotia arcus, is not to be expected and is in fact not realized. InEunotia lunaris, however, the shift of the daughter chromatophores, in relation to the dorsiventrality of the cell, shows not only the same kind of dissymmetry as inEunotia arcus but also the same direction of shifting.The four and four chromatophores inEunotia pectinalis var.polyplastidica correspond to the two chromatophore plates in other species but the are not comparable with the numerous little chromatophore discs of Diatomaceae and other species the number of which decreases with the reduction of cell size.Cells ofEunotia pectinalis var.polyplastidica are capable to move by raphe action.

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Herrn Dr.Franz Berger zum 70. Geburtstag gewidmet.     

Über den Teilungsverlauf des Chloroplasten beiChlamydomonas

Zusammenfassung Die Teilung des Chloroplasten wurde bei zweiChlamydomonas-Arten mit topfförmigem Chloroplasten,Chlamydomonas parallestriata Korschikoff undChlamydomonas cribrum Ettl, an lebenden Zellen laufend verfolgt. Im Unterschied zu den Angaben anderer Autoren kommt der Teilungsbeginn des Chloroplasten der Kernteilung deutlich zuvor. Bei den teilungsbereiten Zellen werden am Vorderrand des Chloroplasten zwei Teilungsfurchen angelegt, die einander gegenüberliegen und den Chloroplasten vom Vorderrand aus zur Basis teilen. In der ersten Phase wird der Randbereich geteilt, wobei sich der Zellkern noch in der Interphase befindet. Erst nach der Teilung des Randbereiches setzt die Mitose ein, und die Teilung des Chloroplasten wird am Basalstück vollendet. Der Chloroplast wächst während der Entwicklung des Tochterprotoplasten erneut zu seiner topfförmigen Gestalt heran. Der beschriebene Teilungsmodus des Chloroplasten wurde auch bei anderenChlamydomonas-Arten beobachtet. Das Vorausgehen des Teilungsbeginns des Chloroplasten vor der Mitose wird diskutiert. Es wird für möglich gehalten, daß die Chloroplastenteilung während der Zellteilung semiautonom verläuft. Der Widerspruch zwischen meinen Untersuchungen und denen anderer Autoren wird geklärt, und es wird betont, daß die morphologische Untersuchung des ganzen Chloroplasten für diese Zwecke nötig ist.

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About the progress of chloroplast division inChlamydomonas

Summary The progress of chloroplast division in twoChlamydomonas species with cup-shaped chloroplasts—Chlamydomonas parallestriata Korschikoff andChlamydomonas cribrum Ettl—is continuously followed with the light microscope in living cells. In contradistinction to the results given by other authors the chloroplast division is starting sooner than the mitosis. Two dividing furrows face each other and appear on the frontal margin of the chloroplast dividing it in direction towards its basal part. During the first stage the lateral part of the chloroplast is divided while the nucleus stays in interphase. Afterwards the mitosis is starting and the division of the basal part of the chloroplast together with the pyrenoid will be finished. The new cup-shaped chloroplast is formed during the development of the young daughter protoplast. The mode of chloroplast division described here has been observed also in otherChlamydomonas species. The preceding of the beginning of chloroplast division with regard to the mitosis is discussed. It is considered that the chloroplast division may be a semiautonomous act in the course of cell division. The differences in my studies and those of other authors are explained and the necessity of the morphological study of the whole chloroplast is stressed.

     

Patterns of asexual reproduction in <Emphasis Type="Italic">Nannochloris bacillaris</Emphasis> and <Emphasis Type="Italic">Marvania geminata</Emphasis> (Chlorophyta,Trebouxiophyceae)

Non-flagellated vegetative green algae of the Trebouxiophyceae propagate mainly by autosporulation. In this manner, the mother cell wall is shed following division of the protoplast in each round of cell division. Binary fission type Nannochloris and budding type Marvania are also included in the Trebouxiophyceae. Phylogenetic trees based on the actin sequences of Trebouxiophyceae members revealed that the binary fission type Nannochloris bacillaris and the budding type Marvania geminata are closely related in a distal monophyletic group. Our results suggest that autosporulation is the ancestral mode of cell division in Trebouxiophyceae. To elucidate how non-autosporulative mechanisms such as binary fission and budding evolved, we focused on the cleavage of the mother cell wall. Cell wall development was analyzed using a cell wall-specific fluorescent dye, Fluostain I. Exfoliation of the mother cell wall was not observed in either N. bacillaris or M. geminata. We then compared the two algae by transmission electron microscopy with rapid freeze fixation and freeze substitution; in both algae, the mother cell wall was cleaved at the site of cell division, but remained adhered to the daughter cell wall. In N. bacillaris, the cleaved mother cell wall gradually degenerated and was not observed in the next cell cycle. In contrast, M. geminata daughter cells entered the growth phase of the next cell cycle bearing the mother and grandmother cell walls, causing the uncovered portion of the plane of division to bulge outward. Such a delay in the degeneration and shedding of the mother cell wall probably led to the development of binary fission and budding.     

Über polykomplexartige Strukturen in den Kernen vonLupinus polyphyllus

In electron micrographs ofLupinus polyphyllus nuclei some of the chromocentres exhibit two distinct regions, a network-like (NR) and a banded one (GR). This heterogeneous type of chromocentres was observed in nearly all cells of vegetative and reproductive tissues (root, leaf primordium of the seedling, young and older foliage leaves, carpel, young and older ovules and pericarp), with the exception of pollen mother cells during the first meiotic division. Results of enzymatic digestion show that GR and NR mainly consist of DNA. These observations suggest that GR and the polycomplexes represent different nuclear phenomena.

Herrn Univ.-Prof. Dr.Walter Leinfellner zum 70. Geburtstag gewidmet.     

Die Lage des Chromatophors in Beziehung zur Systematik vonCymbella-Arten (Bacillariophyceae)

InCymbella the position of the chromatophore corresponds to the taxonomic differentiation into sections. The pyrenoid always shows the same right hand — left hand inclination.

     

红球菌R04细胞的不对称分裂及其在联苯胁迫下的分裂抑制

【目的】研究红球菌R04细胞的分裂方式及联苯对其形态和细胞分裂的影响。【方法】以一株多氯联苯降解菌株(Rhodococcus sp.R04)为研究对象,利用荧光显微镜、扫描电子显微镜及透射电子显微镜分析红球菌R04在不同培养条件下的细胞分裂。【结果】红球菌R04细胞表现出对称分裂(约占30%)和不对称分裂(约占70%)两种分裂方式,且培养条件不影响不对称分裂细胞所占的比例。细胞分裂过程中,隔膜主要分布于细胞长度的30%–50%。在联苯的分解代谢过程中,红球菌R04细胞的生长分裂会受到联苯的抑制,但不影响红球菌R04细胞的分裂方式,在联苯胁迫下,细胞形成丝状化,表现出异常分裂,随着培养时间的延长,在细胞生长指数后期至转换期,细胞能够进行正常分裂。【结论】环境异生型化合物联苯/多氯联苯对其降解菌株——红球菌R04细胞的生长和分裂有较强影响,但是并不影响其分裂方式。     

Cell structure and reproduction process in the Blue-Green algaChamaesiphon

Ultrathin sections were studied in 2 strains and 2 samples from the nature of the genusChamaesiphon, representing 4 different species. Thylakoids are distributed mainly on the periphery of the cells, the cell-wall is probably 2-layered, and variable multilayered mucilaginous envelopes are developed around the cells. The cell division starts, as well as in otherCyanophyceae, by the invagination of the cytoplasmic membrane and of cell-wall layers into the protoplast; the mucilaginous envelopes—pseudovaginae—do not participate in this process but they form only the firm sheaths around the cells. The way of reproduction is, therefore, essentially the same as that described in other chroococcal Blue-Green algae (e.g.,Synechococcus), and the main difference is the polarized growth of theChamaesiphon cells. The taxonomical position of chamaesiphonoid algae is not as isolated as it was earlier supposed, the similarity withEntophysalidaceae is evident.