Rhizoplast and rootlet system of the flagellar apparatus of Chlamydomonas moewusii

1979 ◽  
Vol 39 (1) ◽  
pp. 373-381 ◽  
Author(s):  
K.R. Katz ◽  
R.J. McLean
Keyword(s):  
Endoplasmic Reticulum ◽  
Functional Role ◽  
Smooth Endoplasmic Reticulum ◽  
Central Area ◽  
Flagellar Apparatus ◽  
The Other ◽  
Basal Bodies ◽  
Chlamydomonas Moewusii ◽  
Cytoplasmic Microtubules ◽  
Over The Top

The ultrastructure of the flagellar apparatus of Chlamydomonas moewusii was examined in detail. Two rhizoplasts were found associated with the basal bodies of this biflagellate and were observed to extend to the central area of the cell. A segment of smooth endoplasmic reticulum ran parallel to each rhizoplast. These 2 segments anastomose beneath the basal bodies and the tubule proceeds over the top of the distal connecting fibre. A functional role for the smooth endoplasmic reticulum in these locations is discussed. Four sets of rootlet microtubules emanate from a region between the 2 basal bodies and the distal connecting fibre. Two sets have a three-over-one arrangement and the other 2 sets are doublets. Cytoplasmic microtubules were seen associated with possible nucleating sites on the rootlet microtubules. The association of the observed structures are discussed and compared to the flagellar apparatus of C. reinhardtii.

scholarly journals Organization of the flagellar apparatus and associate cytoplasmic microtubules in the quadriflagellate alga Polytomella agilis.

1976 ◽  
Vol 69 (1) ◽  
pp. 106-125 ◽  
Author(s):  
D L Brown ◽  
A Massalski ◽  
R Patenaude
Keyword(s):  
Anterior Part ◽  
Flagellar Apparatus ◽  
Microtubule Assembly ◽  
Immunofluorescent Staining ◽  
Body Region ◽  
Basal Bodies ◽  
Cytoplasmic Microtubule ◽  
Large Numbers ◽  
Attachment Sites ◽  
Cytoplasmic Microtubules

The organization of microtubular systems in the quadriflagellate unicell Polytomella agilis has been reconstructed by electron microscopy of serial sections, and the overall arrangement confirmed by immunofluorescent staining using antiserum directed against chick brain tubulin. The basal bodies of the four flagella are shown to be linked in two pairs of short fibers. Light microscopy of swimming cells indicates that the flagella beat in two synchronous pairs, with each pair exhibiting a breast-stroke-like motion. Two structurally distinct flagellar rootlets, one consisting of four microtubules in a 3 over 1 pattern and the other of a striated fiber over two microtubules, terminate between adjacent basal bodies. These rootlets diverge from the basal body region and extend toward the cell posterior, passing just beneath the plasma membrane. Near the anterior part of the cell, all eight rootlets serve as attachment sites for large numbers of cytoplasmic microtubules which occur in a single row around the circumference of the cell and closely parallel the cell shape. It is suggested that the flagellar rootless may function in controlling the patterning and the direction of cytoplasmic microtubule assembly. The occurrence of similar rootlet structures in other flagellates is briefly reviewed.

Fine structure of compound eyes of cicindela tranquebarica herbst (coleoptera: cicindelidae)

1978 ◽  
Vol 36 (2) ◽  
pp. 604-605
Author(s):  
Janice E. Kuster
Keyword(s):  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Rough Endoplasmic Reticulum ◽  
Cell Nucleus ◽  
The Other ◽  
Pigment Cells ◽  
Compound Eyes ◽  
Basal Bodies ◽  
Protein Deposits ◽  
Corneal Lens

The fine structure of photopic eucone eyes of Cicindela tranquebarica adults was examined using cryofracture SEM, TEM, and freeze-etch techniques. A “subcorneal layer” can be distinguished between the corneal lens and crystalline cone. In surface view (Fig. 1) this layer consists of concave polygons (po). It has parabolic lamellae (lm) of endocuticle consisting of microfibrils (mf) having a chitin core with protein deposits along their lengths (Fig. 2). Two primary pigment cells (lp) are devoid of pigment granules, but are rich in rough endoplasmic reticulum (rer) and surround a crystalline thread (ct) (Fig. 3). Extensions of the crystalline thread form inter-retinular fibers (f) containing microtubules between retinula cells 1/2, 3/4, 5/6, and 7/1 (Figs. 4, 5).Distal to each retinula cell nucleus are two basal bodies (bb), one perpendicular to the other (Fig. 4). The proximal body extends two fibrillar feet which fuse to form a horizontally banded ciliary rootlet which extends the retinula length peripheral to the rhabdom.

Ultrastructure and development of the flagellar apparatus and flagellar motion in the colonial graeen alga Astrephomene gubernaculifera

1983 ◽  
Vol 63 (1) ◽  
pp. 21-41
Author(s):  
H.J. Hoops ◽  
G.L. Floyd
Keyword(s):  
Basal Body ◽  
Rotational Symmetry ◽  
Amorphous Material ◽  
Flagellar Apparatus ◽  
The Other ◽  
Basal Bodies ◽  
Mature Cell ◽  
Embryonic Cleavage ◽  
Development Proceeds ◽  
Concurrent Events

Immediately following embryonic cleavage, the cells of Astrephomene have four equal-sized basal bodies, two of which are connected by a striated distal fibre and two striated proximal fibres. The four microtubular rootlets, which alternate between having 3/1 and 2 members, are arranged cruciately. The two basal bodies that are connected by the striated fibres then extend into flagella, while the two accessory basal bodies are now markedly shorter. At this stage the flagellar apparatus has 180 degrees rotational symmetry and is very similar to the flagellar apparatus of the unicellular Chlamydomonas and related algae. Development proceeds with a number of concurrent events. The basal bodies begin to separate at their proximal ends and become nearly parallel. Each striated proximal fibre detaches at one end from one of the basal bodies. Each half of the flagellar apparatus, which consists of a flagellum and attached basal body, an accessory basal body, two rootlets and a striated fibre (formerly one of the proximal striated fibres), rotates about 90 degrees, the two halves rotating in opposite directions. An electron-dense strut forms near one two-membered rootlet and grows past both basal bodies. During this time a fine, fibrous component appears between newly developed spade-like structures and associated amorphous material connected to each basal body. The basal bodies continue to separate as the distal fibre stretches and finally detaches from one of them. These processes result in the loss of the 180 degree rotational symmetry present in previous stages. Although the flagella continue to separate, there is no further reorganization of the components of the flagellar apparatus. In the mature cell of Astrephomene, the two flagella are inserted separately and are parallel. The four microtubular rootlets are no longer arranged cruciately. Three of the rootlets are nearly parallel, while the fourth is approximately perpendicular to the other three. A straited fibre connects each basal body to the underside of the strut. These fibres run in the direction of the effective stroke of the flagella and might be important either in anchoring the basal bodies or in the initiation of flagellar motion. Unlike the case in the unicellular Chlamydomonas, the two flagella beat in the same direction and in parallel planes. The flagella of a given cell may or may not beat in synchrony. The combination of this type of flagellar motion and the parallel, separate flagella appears to be suited to the motion of this colonial organism.

scholarly journals STRATIFICATION AND SUBSEQUENT BEHAVIOR OF PLANT CELL ORGANELLES

1963 ◽  
Vol 18 (2) ◽  
pp. 441-457 ◽  
Author(s):  
G. Benjamin Bouck
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Rough Endoplasmic Reticulum ◽  
Lipid Droplets ◽  
Smooth Endoplasmic Reticulum ◽  
The Other ◽  
Cell Organelles ◽  
Large Unit ◽  
Original Length ◽  
Subsequent Behavior

Living excised roots of pea were centrifuged at 20,000 g for 24 hours, and the behavior of organelles was followed by electron microscopy at various intervals after centrifugation. With these forces, organelles are not perceptibly or irreversibly damaged, nor is the viability of the whole root destroyed. Organelles stratify generally in the order of lipid (centripetal pole), vacuoles, smooth endoplasmic reticulum and dictyosomes, proplastids (without starch), mitochondria, rough endoplasmic reticulum, proplastids with starch. The nucleus distends from the vacuolar region to the extreme centrifugal pole of the cell, while the chromatin and nucleolus seek the centrifugal pole of the nucleus. During the redistribution of organelles the rough endoplasmic reticulum is among the first to reorient, and possible explanations for this are discussed. Mitochondria can be stretched elastically many times their original length, but proplastids seem fairly rigid. Small vacuoles, forced together during centrifugation, apparently may fuse to form a large unit. Lipid droplets, on the other hand, tend to remain separate. Dictyosomes and smooth endoplasmic reticulum layer in the same region of the centrifuged cell, indicating a density similarity between these two organelles.

Ultrastructural aspects of conidiogenesis in the entomogenous hyphomycete Nomuraea rileyi

1982 ◽  
Vol 60 (1) ◽  
pp. 26-33 ◽  
Author(s):  
J. C. Pendland ◽  
D. G. Boucias
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Envelope ◽  
Smooth Endoplasmic Reticulum ◽  
Wall Layer ◽  
The Other ◽  
Wall Material ◽  
Nomuraea Rileyi ◽  
Conidium Formation ◽  
Woronin Body

Conidia in Nomuraea rileyi are produced basipetally from a phialide apex. Production of primary and all successive conidia appears to be enteroblastic, and only the inner, newly formed wall layer of the phialide surrounds developing conidia. Conidium formation ceases as layers of inner wall material accumulate at the phialide apex. In some cases, a pluglike structure resembling a Woronin body may cause cessation of conidiogenesis. Conidia are delimited by formation of a double septum. Since one half of the septum forms the base of the "older" conidium and the other half forms the apex of the next conidium, separation of successive conidia is schizolytic. Plasmalemmasomes, lomasomes, and smooth endoplasmic reticulum are often seen in association with septa and walls of conidiogenous cells. Transverse fibrils may be observed in some walls. Extensive vacuolization is common in older cells. Glycogen is present in conidiogenous cells and in conidia, which become very electron dense as they mature. An extranuclear plaque, an ascomycetous characteristic, may be observed on the nuclear envelope.

An Ultrastructural Study of the Differentiation of the Spermatozoid of Equisetum

1973 ◽  
Vol 12 (1) ◽  
pp. 95-129
Author(s):  
J. G. DUCKETT
Keyword(s):  
Endoplasmic Reticulum ◽  
Cell Wall ◽  
Nuclear Envelope ◽  
Outer Surface ◽  
Single Layer ◽  
Multilayered Structure ◽  
The Other ◽  
Basal Bodies ◽  
Parallel Plates ◽  
Anterior Edge

The ultrastructure of spermatogenesis in Equisetum is described with particular reference to the origin and development of the multilayered structure (MLS) and nuclear metamorphosis. Simultaneously with the formation of centrioles, by the fragmentation of the blepharoplast, in young spermatids, the MLS appears in their vicinity. This comprises 4 layers recalling the Vierergruppe of bryophyte spermatids. The outer layer, or microtubular band, consists of juxtaposed microtubules. The three inner lamellar strata, which lie along the anterior edge of the microtubular band, are composed of parallel plates oriented at 35-45° to the axes of the microtubules. Keels are present on the microtubules where these overlie the lamellar layers. A mitochondrion lies subjacent to the lamellar layers and on the outer surface of the anterior edge of the microtubular band is a crest of osmiophilic material. The position of the osmiophilic crest suggests that it may have a role in microtubule synthesis. However, its persistence in the mature gametes after microtubular elongation has ceased, and its banded substructure, reminiscent of flagellar roots, perhaps indicate that its function is mainly mechanical in holding the microtubular band together. Approximately oval in shape and overlain by less than 50 short microtubules initially, the lamellar strata and subjacent mitochondrion rapidly increase in length. Eventually they form a strip 15-20 µm in length overlain by over 300 microtubules. This extensive microtubular band in Equisetum is more likely related to the final shape of the nucleus in the mature gamete than to the presence of numerous flagella. The entire MLS now becomes associated with the nucleus. The microtubular band is closely adpressed to the nuclear envelope and acts as a cytoskeletal framework along which the nucleus undergoes elongation and coiling. Initially the lamellar strip and mitochondrion run along the nuclear envelope with one of their edges touching it and the other projecting into the cytoplasm. However, continuous elongation of the microtubules throughout nuclear metamorphosis results in the gradual separation of the strip and mitochondrion beyond the anterior tip of the nucleus. Simultaneously, the posterior parts of the nucleus become ensheathed by rearward extension of the microtubular band. The centrioles arrange themselves in a single layer on the outer surface of the microtubular band and during the early stages of nuclear metamorphosis give rise to flagella from their distal ends, concomitantly undergoing differentiation into basal bodies. Intense Golgi activity during early and mid-spermatid stages is thought to be related to the accumulation of mucopolysaccharides between the cell wall and cell membrane. In the mid-spermatids rough endoplasmic reticulum is closely associated with the plastids which later accumulate starch, a characteristic feature of spermatogenesis in archegoniate plants.

scholarly journals The effects of triton X-100 on the transfer of mannose, glucose and N-acetylglusomine phosphate to dolichol monophosphate by preparations of rough and smooth endoplasmic reticulum and of mitochondria of rat liver

1979 ◽  
Vol 184 (2) ◽  
pp. 391-397 ◽  
Author(s):  
T Coolbear ◽  
S Mookerjea ◽  
F W Hemming
Keyword(s):  
Endoplasmic Reticulum ◽  
Enzyme Activity ◽  
Outer Membrane ◽  
Smooth Endoplasmic Reticulum ◽  
The Other ◽  
Outer Face ◽  
Mitochondrial Enzyme ◽  
Glucose Transfer ◽  
Specific Activities ◽  
Triton X

Triton X-100 and exogenous dolichol monophosphate have been used to investigate the nature of enzymes responsible for the transfer of mannose, glucose and N-acetylglucosamine phosphate from nucleotide donors to dolichol monophosphate in vesicles derived from rough and smooth endoplasmic reticulum and mitochondria. Mitochondria were shown to contain the highest specific activities of these enzymes. The responses of the glycosyltransferases to increasing concentrations of Triton X-100 and the effect on these responses of exogenous dolichol monophosphate suggest that the enzymes for mannose and glucose transfer are less hydrophobic, and therefore less intrinsic, in the membrane than the enzyme for N-acetylglucosamine phosphate transfer. In smooth vesicles the results are consistent with mannosyl- and glucosyl-transferases being located at both inner and outer faces of the membrane. In rough vesicles and in mitochondria mannosyl- and glucosyl-transferases were confirmed at the outer face. There is, however, only one site of N-acetylglucosamine phosphate transfer, this being more hydrophobically located in the membrane than the other sites of glycosyl transfer. Mitochondrial enzyme activity closely resembled that of rough endoplasmic reticulum in response to Triton X-100 and exogenous dolichol monophosphate, and is probably associated with the outer membrane.

Control of intracellular Ca2+ activity in rat myometrium

1977 ◽  
Vol 232 (1) ◽  
pp. 50-58 ◽  
Author(s):  
R. A. Janis ◽  
D. J. Crankshaw ◽  
E. E. Daniel
Keyword(s):  
Skeletal Muscle ◽  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Control System ◽  
Sarcoplasmic Reticulum ◽  
Smooth Endoplasmic Reticulum ◽  
Membrane Vesicles ◽  
High Energy ◽  
The Other ◽  
Relative Potential

Four fractions enriched, respectively, in plasma membrane (PM), smooth endoplasmic reticulum (SER), rough endoplasmic reticulum (RER), and mitochondria were isolated from estrogen-dominated rat myometrium. Ca2+ uptake by these fractions was studied in order to estimate the relative potential of the corresponding organelles for controlling intracellular Ca2+ activity. Ca2+ uptake properties of the PM, SER, and RER fractions were similar except that potentiation by oxalate was in the order RER greater than or equal SER greater than PM. However, studies with the ionophores X-537A and A23187 suggested that Ca2+ was transported into the lumen of membrane vesicles of all these fractions. Unlike that of skeletal muscle sarcoplasmic reticulum, Ca2+ uptake by the myometrial fractions was not supported by high-energy compounds other than ATP. Mitochondria took up much less Ca2+ at low, and much more Ca2+ at high, free Ca2+ concentrations than did the other fractions. The amount of Ca2+ taken up in 30 s from a 1 muM free Ca2+ solution in the presence of ATP was similar for all fractions. These results suggested that mitochondria may act as an important Ca2+ control system in rat myometrium when the intracellular Ca2+ concentration is near 1 muM or higher, whereas the PM, SER, and RER may be of major importance at Ca2+ levels of 0.3 muM or lower.

scholarly journals Heterogeneity of cyclic nucleotide phosphodiesterases in liver endoplasmic reticulum

1983 ◽  
Vol 213 (1) ◽  
pp. 89-97 ◽  
Author(s):  
B Cercek ◽  
S R Wilson ◽  
M D Houslay
Keyword(s):  
Endoplasmic Reticulum ◽  
Cyclic Amp ◽  
Cyclic Nucleotide ◽  
Enzyme Activities ◽  
Smooth Endoplasmic Reticulum ◽  
Gradient Centrifugation ◽  
Polyacrylamide Gel Electrophoresis ◽  
Competitive Inhibitor ◽  
The Other ◽  
Phosphodiesterase Activity

A microsomal fraction from rat liver was subfractionated into three rough endoplasmic reticulum fractions RIII, RII and RI, together with a smooth endoplasmic reticulum plus Golgi fraction. Cyclic nucleotide phosphodiesterase activity was found in all fractions. Subsequently it was shown that Golgi fractions were essentially devoid of cyclic AMP phosphodiesterase activity and the activity resided in the smooth endoplasmic reticulum fraction. The activity of the endoplasmic reticulum constituted some 20% of the homogenate activity, with the major fraction of this being associated with the RII fraction and the least with the RI fraction. With the exception of the activity of the RI fraction, which was a peripheral enzyme, all of the other enzyme activities were integral, requiring detergent or repeated freeze-thawing to effect solubilization. All of the activities appeared to be exposed at the external surface of the endoplasmic reticulum, as they were inactivated by trypsin under conditions where glucose 6-phosphatase was not. All of these activities displayed distinct sensitivities to both thermal and trypsin inactivation, yielding activity decays consistent with a single enzyme species being present in each case. The freeze-thaw-solubilized enzymes yielded single symmetrical peaks on sucrose-density-gradient centrifugation and polyacrylamide-gel electrophoresis. The sedimentation coefficients for the enzymes in the smooth-endoplasmic-reticulum-plus-Golgi, RIII, RII and RI fractions were 3.2S, 4.2S, 4.5S and 4.5S respectively. Whereas the activity in the smooth-endoplasmic-reticulum-plus-Golgi fraction exhibited normal Michaelis kinetics, those in the other fractions yielded kinetics indicative of apparent negative co-operativity. All of the enzymes exhibited low Km values towards cyclic AMP. The enzymes did not appear to be regulated by Ca2+ or calmodulin. ZnCl2 was found to be a potent non-competitive inhibitor of the enzyme in all fractions. NaF was a weak non-competitive inhibitor. The bilayer fluidizing agent benzyl alcohol exerted dissimilar effects on the enzyme activities. It is concluded that the endoplasmic reticulum displays lateral heterogeneity, with single, rather distinct, cyclic AMP phosphodiesterases being found in the different fractions.

In Vitro Induction of Crystals of MT Protein by Vinblastine-Colcemid in Mouse Spermatids

1974 ◽  
Vol 32 ◽  
pp. 132-133
Author(s):  
John J. Wolosewick ◽  
John H. D. Bryan
Keyword(s):  
Endoplasmic Reticulum ◽  
Smooth Endoplasmic Reticulum ◽  
Nuclear Ring ◽  
Rough Er ◽  
Distal Direction ◽  
In Vitro Induction

Early in spermiogenesis the manchette is rapidly assembled in a distal direction from the nuclear-ring-densities. The association of vesicles of smooth endoplasmic reticulum (SER) and the manchette microtubules (MTS) has been reported. In the mouse, osmophilic densities at the distal ends of the manchette are the organizing centers (MTOCS), and are associated with the SER. Rapid MT assembly and the lack of rough ER suggests that there is an existing pool of MT protein. Colcemid potentiates the reaction of vinblastine with tubulin and was used in this investigation to detect this protein.

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