F-actin localization during trochoblast differentiation embryos

Development ◽  
1991 ◽  
Vol 112 (3) ◽  
pp. 833-845
Author(s):  
F. Serras ◽  
J.E. Speksnijder
Keyword(s):  
Basal Body ◽  
Cytochalasin B ◽  
Dorsal Side ◽  
Dorsoventral Axis ◽  
Patella Vulgata ◽  
Apical Cytoplasm ◽  
Locomotory Behavior ◽  
Basal Apparatus ◽  
Actin Localization ◽  
Swimming Capacity

We have studied the development of the ciliated, Patella vulgata trochophore larvae. This organ, the different clones of trochoblasts. In each of these filamentous (F-) actin is formed at the time that which we visualized with TRITC-phalloidin, is cilia that crosses each trochoblast. Isolated quartets of animal micromeres (from which the form rows of cilia and F-actin bands at the proper embryos, the trochoblasts shift their position form a ring of differentiated prototroch cells with a encircling the entire larva. At the dorsal side, a and thus a double band of F-actin is present. In double F-actin band are found in trochophores in which dorsoventral axis is inhibited experimentally. shows that the F-actin band extends from the apical cytoplasm of the prototroch cells. At the rootlet connected to the basal body of each cilium can the cytoplasm toward the nucleus, and a band of actin- interconnect neighboring basal apparatus. Treatment of cytochalasin B disrupts the organization of the F- TRITC-phalloidin, affects the angle of the effective reduces their swimming capacity. This suggests that for the normal locomotory behavior of the Patella

Ultrastructure of the basal body apparatus in epidermal cells of a sponge larva (Aplysilla SP: Demospongiae)

1992 ◽  
Vol 50 (1) ◽  
pp. 928-929
Author(s):  
R.L. Pinto ◽  
R.M. Woollacott
Keyword(s):  
Sodium Bicarbonate ◽  
Epoxy Resin ◽  
Basal Body ◽  
Phosphate Buffer ◽  
Similar Data ◽  
Basal Apparatus ◽  
Striated Rootlet ◽  
The Common ◽  
Basal Foot ◽  
Sexually Mature

The basal body and its associated rootlet are the organelles responsible for anchoring the flagellum or cilium in the cytoplasm. Structurally, the common denominators of the basal apparatus are the basal body, a basal foot from which microtubules or microfilaments emanate, and a striated rootlet. A study of the basal apparatus from cells of the epidermis of a sponge larva was initiated to provide a comparison with similar data on adult sponges.Sexually mature colonies of Aplysillasp were collected from Keehi Lagoon Marina, Honolulu, Hawaii. Larvae were fixed in 2.5% glutaraldehyde and 0.14 M NaCl in 0.2 M Millonig’s phosphate buffer (pH 7.4). Specimens were postfixed in 1% OsO4 in 1.25% sodium bicarbonate (pH 7.2) and embedded in epoxy resin. The larva ofAplysilla sp was previously described (as Dendrilla cactus) based on live observations and SEM by Woollacott and Hadfield.

Intracellular transport and secretion of fibroin in the posterior silk gland of the silkworm Bombyx mori

1981 ◽  
Vol 50 (1) ◽  
pp. 19-44 ◽  
Author(s):  
S. Sasaki ◽  
E. Nakajima ◽  
Y. Fujii-Kuriyama ◽  
Y. Tashiro
Keyword(s):  
Intracellular Transport ◽  
Cytochalasin B ◽  
Silk Gland ◽  
Luminal Surface ◽  
Golgi Bodies ◽  
Apical Cytoplasm ◽  
Radial Microtubule System ◽  
Microfilament System ◽  
Silkworm Bombyx Mori ◽  
Posterior Silk Gland

Intracellular transport and secretion of fibroin in the posterior silk gland cells of the silkworm, Bombyx mori, were investigated in relation to the radial microtubule and circular microtubule-microfilament systems of the cells. The silk glands were pulse-labelled for 3 min with [3H]glycine in vitro and then chased in media containing excess cold glycine and in some cases antimitotic reagents (colchicine or vinblastine) or cytochalasin (B or D), and the flow of the label in the glands was investigated by radioautography. It was revealed that the label initially located over the rough endoplasmic reticulum subsequently moves to the Golgi bodies to be condensed there. The secretory granules of fibroin or fibroin globules thus formed are transported via the radial microtubule system to the apical cytoplasm to be secreted there under some regulation by the circular microtubule-microfilament system. In the presence of colchicine or vinblastine, the secretion of fibroin was suppressed an marked accumulation of fibroin globules in the Golgi regions was observed, while in the presence of cytochalasin B or D the secretion was accelerated and extensive invagination of the luminal surface, which was probably due to the serial exocytosis of fibroin globules, was observed. These results suggest that the radial microtubule system and the circular microtubule-microfilament system are responsible for intracellular transport of fibroin globules from Golgi bodies to the apical cytoplasm and secretion by exocytosis at the luminal surface, respectively.

Ultrastructure of the flagellar roots in Chlamydomonas gametes

1984 ◽  
Vol 67 (1) ◽  
pp. 133-143
Author(s):  
R.L. Weiss
Keyword(s):  
Basal Body ◽  
Direct Contact ◽  
The Other ◽  
Basal Bodies ◽  
Flagellar Roots ◽  
Mating Structure ◽  
Membrane Extension ◽  
Microtubular Root ◽  
Basal Apparatus ◽  
Microtubular System

The cytoskeleton of Chlamydomonas reinhardtii gametes has been studied by electron microscopy. The microtubular system, consisting of four flagellar roots inserted into the basal apparatus, is shown to include two daughter basal bodies and two striated fibres, newly described in this report. One new fibre associates with the 3-over-1 root and is similar to its counterpart, the striated fibre of the 2-member root. These similar root fibres connect each daughter basal body to the V-shaped microtubular root pair. The other new striated fibre joins the daughter basal body to both flagellar roots and is similar to the proximal striated fibre. In mt+ gametes, the conventional root microtubules make direct contact with the doublet zone of the non-activated mating structure. During activation, doublet zone microfilaments associate with the daughter basal body and the finely striated fibre of the 3-over-1 root. These observations suggest that the cytoskeleton acts as a scaffolding for membrane extension by the mt+ mating structure microfilaments.

scholarly journals Centrin Scaffold in Chlamydomonas reinhardtii Revealed by Immunoelectron Microscopy

2005 ◽  
Vol 4 (7) ◽  
pp. 1253-1263 ◽  
Author(s):  
Stefan Geimer ◽  
Michael Melkonian
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Immunoelectron Microscopy ◽  
Basal Body ◽  
Flagellar Apparatus ◽  
Single Copy ◽  
Asymmetric Structure ◽  
Transitional Region ◽  
Ef Hand ◽  
Basal Apparatus ◽  
Postembedding Immunoelectron Microscopy

ABSTRACT In the flagellate green alga Chlamydomonas reinhardtii the Ca2+-binding EF-hand protein centrin is encoded by a single-copy gene. Previous studies have localized the protein to four distinct structures in the flagellar apparatus: the nucleus-basal body connector, the distal connecting fiber, the flagellar transitional region, and the axoneme. To explain the disjunctive distribution of centrin, the interaction of centrin with as yet unknown specific centrin-binding proteins has been implied. Here, we demonstrate using serial section postembedding immunoelectron microscopy of isolated cytoskeletons that centrin is located in additional structures (transitional fibers and basal body lumen) and that the centrin-containing structures of the basal apparatus are likely part of a continuous filamentous scaffold that extends from the nucleus to the flagellar bases. In addition, we show that centrin is located in the distal lumen of the basal body in a rotationally asymmetric structure, the V-shaped filament system. This novel centrin-containing structure has also been detected near the distal end of the probasal bodies. Taken together, these results suggest a role for a rotationally asymmetric centrin “seed” in the growth and development of the centrin scaffold following replication of the basal apparatus.

Regeneration from isolated half limbs in the upper arm of the axolotl

Development ◽  
1985 ◽  
Vol 89 (1) ◽  
pp. 333-347
Author(s):  
Peter Wigmore ◽  
Nigel Holder
Keyword(s):  
Regional Differences ◽  
Dorsal Side ◽  
Posterior Half ◽  
Upper Arm ◽  
Digit Number ◽  
Dorsoventral Axis ◽  
Anterior Dorsal ◽  
Posterior Anterior

A technique enabling the isolation of half limb stumps using strips of skin from the head is described. Using this technique posterior, anterior, dorsal and ventral halves of the upper arms of axolotls were constructed. All halves produced regenerates and regional differences were shown in the regenerative and regulative abilites of the different halves. Posterior half stumps regenerated limbs with a mean digit number of 3·9 and had a normal dorsoventral muscle pattern. Anterior halves produced hypomorphic limbs with a mean digit number of 1·2 while dorsal and ventral halves produced an average of 3·8 and 2·6 respectively. Regenerates from dorsal half stumps had a normal dorsoventral axis but the majority of those from ventral halves were either double ventral or had little muscle on the dorsal side of the limb.

The site of fertilisation determines dorsoventral polarity but not chirality in the zebra mussel embryo

Zygote ◽  
1998 ◽  
Vol 6 (2) ◽  
pp. 125-135 ◽  
Author(s):  
Craig Marc Luetjens ◽  
Adriaan W.C. Dorresteijn
Keyword(s):  
Early Stage ◽  
Dorsal Side ◽  
Entry Point ◽  
Cleavage Furrow ◽  
Experimental Conditions ◽  
Cell Stage ◽  
Dorsoventral Axis ◽  
Dorsoventral Polarity ◽  
Sperm Entry ◽  
Two Factors

The dorsoventral polarity of unequally cleaving spiralian embryos becomes established at an early stage. The factors determining the position of the dorsoventral axis are still unknown. We present data showing that the sperm entry point (SEP) in both normal development and under experimental conditions determines the position of the first cleavage furrow in Dreissena embryos. The position of the spindles at second cleavage is directed by the site of fertilisation also, and the large, dorsal D quadrant of the 4-cell stage always forms opposite the SEP. The spiral chirality at third cleavage seems to be independent of both the fertilisation point and the arrangement of the quadrants. Dextral and sinistral third cleavages are found in a single egg batch, but sinistral cleavages prevail. We postulate that two factors coordinate the proper positioning of the dorsoventral axis. The sperm entry point as an epigenetic factor determines the dorsal side of the embryo. But since the dorsoventral axis forms oblique to the first cleavage furrow, this first decision is still ambiguous, and a second decision is required that, due to the alternative chirality of spiral cleavage, finally sets up the dorsoventral axis.

The Xenopus homologue of Bicaudal-C is a localized maternal mRNA that can induce endoderm formation

Development ◽  
2000 ◽  
Vol 127 (10) ◽  
pp. 2053-2062 ◽  
Author(s):  
O. Wessely ◽  
E.M. De Robertis
Keyword(s):  
Rna Binding ◽  
Ectopic Expression ◽  
Dorsal Side ◽  
Mesoderm Induction ◽  
Midblastula Transition ◽  
Dorsoventral Axis ◽  
Maternal Mrna ◽  
Zygotic Transcription ◽  
Maternal Mrnas ◽  
Synthetic Mrna

In Xenopus, zygotic transcription starts 6 hours after fertilization at the midblastula transition and therefore the first steps in embryonic development are regulated by maternally inherited proteins and mRNAs. While animal-vegetal polarity is already present in the oocyte, the dorsoventral axis is only established upon fertilization by the entry of the sperm and the subsequent rotation of the egg cortex. In a screen for maternal mRNAs whose stability is regulated by this cortical rotation, we isolated the Xenopus homologue of the Drosophila gene Bicaudal-C (xBic-C). It encodes a putative RNA-binding molecule expressed maternally and localized predominantly to the vegetal half of the egg. Upon fertilization and cortical rotation, xBic-C mRNA is displaced together with the heavy yolk towards the future dorsal side of the embryo. In UV-ventralized embryos, xBic-C is polyadenylated less than in untreated embryos that undergo cortical rotation. Overexpression of xBic-C by injection of synthetic mRNA in whole embryos or in ectodermal explants leads to ectopic endoderm formation. This endoderm-inducing activity is dependent on the presence of the RNA-binding domain of the protein. In contrast to the two other known maternally encoded endoderm inducers, Vg1 and VegT, xBic-C ectopic expression leads specifically to endoderm formation in the absence of mesoderm induction.

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