Cytoskeleton of Euplotes focardii : Morphology and morphogenesis

Cell Biology

International

Reports,

Vol. 14, Abstracts

Supplement

THE CYTOSKELETON-MEMBRANE INTERACTIObJ OF THE DEVELOPING NERVE CELLS. G.Skibo,O.Beresovskaja,D.Rusakov. Bogomolctz Institute of Physiology, Kiev, USSR Ultrastructural analysis of distribution of overmembrane glycocomplexes in cultured nerve cells was carried out with the use of colloidal gold lectins.Topography of this markers bound with different parts of neuronal membrane in various developmental stages was morphometritally investigated after cell microtubules (mt) or microfilaments (mf) had been destroyed. Main spatial parameters of observed marker distribution were estimated by means of a statistical stereological approach worked out ad hoc.After destruction of qtoskeleton elements the clustered type of WGA-Au markers remained the sai !me whereas the size of clusters increased in average( after the mf destruction it was greater than after mt one).A similar marker distribution typical for the control neuron outgrowths was transformed either into the uniform ordered one in 5 div cells or into the one-granulated one in 15 div cells.HPL-Au markers were distributed uniformly on the membrane both in control and in the preparations subjected to cytoskeleton damage. However the HPL-Au distribution density increased under the destroying influence.The quantitative statistical date obtained al-

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low

to determine

that the degree

1990

197

TRANSCNWTIONS IN IEISSEI

CYTO!XELETM

CILIATE

Makgorzata Department of Experimental

TI-R!

PARAWWYLA

Frontczak,

Maria

Jerka-Dziadosz. M. Nencki Institute Warsaw,Poland.

of Cell Biology,

Biology,

The dynamics of cortical cytoskeletal structures (basal bodies, MTOCs, microtubular networks, striated ciliary rootlets and basal body associated filaments) accompanying the development of nuclear apparatus during conjugation was studied by EM of extracted cytoskeletons and immunostaining with specific polyand monoclonal antibodies. Conjugation in P. weissei involves total fusion of two mates accompanied by sequential resorption of most of the ciliary structures. The new dorsal

bristle

complexformed at fertilization

persits

in the zygocyst until exconjugant morphogenesis. This complex undergoes conjugation specific transformation involving resorption of one basal body from the couplet. Imnunofluorescent studies revealed differences in reactivity of fibrillar structures with antibodies in fusing mates and in the zygocyst. The type of reactivity corresponds to the morphogenetic status of the conjugating cells. Cytoskeletal transformations during sexual processes will be compared with the cytoskeleton dynamics in the cell cycle and morphogenesis.

of participation

of mt and mf in lateral movity and assymetrical distribution of surface membrane components are not identical either in the different parts of nerve cells or at the different stages of their development,

*-. CYTOSKELETON OF w MORPHOLOGY AND MORPHOGENESiS Lucia Arregui*, Silvia Garcia*, Susana Sermno*, Ana Sola*, Almudena Guinea*, Alessandro Valbonesi** and Pierangelo Luporini**, *Dep. Microbiologia, Fat. Biologia, UCM, 28040 di Biologia Cellulare, Madrid, Spain; **Dipartimento Universita degli Studi di &merino, Italia. The specimens of s come from samples collected from a small cove, east of Italian Antartic base located at terra Nova Bay. The silver impregnation reveals the infraciliary pattern of this species. Ventral somatic infraciliature consists of 9-10 frontoventral cini, 5 transverse cirri, 2-3 caudal cirri and 2 left marginal cini. Dorsal somatic infraciliature is composed by 9 dorsal and 2 dorsolatexal kineties, composed by dikinetids. The oral infraciliature is formed by one adoral wne of membranelles (AZM) and one peroral membrane (PM). This species presents a complex fibrillar cytoskeleton. At the most anterior third of the cell there is a dense fibrillar structure, from which depart thick fibers that reach the vicinity of the anterior part of the AZM. Another fibrillar bundles depart from this structure and reach each transverse cirri. On the oral zone, a complex of cytoskeletal fibers connects the PM with the posterior part of the AZM. During bipartition the new oral infraciliature (PM and AZM) originates from the kinetosomal proliferation of a primordium formed “de nova” at the left posterior zone of the AZM. Frontoventral and transverse cirri of two daughter cells originate from 5 lineal primordia placed, according to a longitudinal pattern of fibrillar bundles in the central zone. Caudal cirri come from the proliferation of 2 dorsal somatic

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kinetiesandmarginalcinioriginatefromtheoralprimordium.

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CYTOSKELETAL ELEMENTS SENSILLA

IN

INSECT

Uwe Wolfrum. Inst.of Zoology, University of Regensburg, D-8400 Regensburg. Insects gether information about their ienvironment using special sense organules, the sensilla. Cytoskeletal elements of both mechanosensitive scolopidia, and thermo-/ hygrosensitive sensilla may play an important role in sensillum function. Their most prominent

cytoskeletal

scolopale

localized

stxuctures

are

a

in the innermost

auxiliary cell and the cil.iary rootlets of the sensory cells. Both axe analysed here

using cyto- and immunohistochemical methods for light and electron microscopy. The scolopale is composed of microtubules ments.

embedded

in

bundles

of actin

fila-

Immunohistochemical test with antimyosins failed to demonstrate myosin in the scolopale. lizes with

findings

motile

Whereas anti-tropomyosin colocaits actin filament bundles. Both

suggest a/stabilizing

role

of the

rather

then a

actin filament within This supports current hypo-

the scolopale. theses for an involvement of mechanical forces in the sensory transduction of both types of sensilla. The scolopale may protect the sensory dendrites from mechanical stimuli other than adequate. Anti-a-actinin reacts within the crossstriated cells.

ciliaxy

Because

xootlet no other

of the sensory component of these

filamentous rootlets has been characterized so fax, their role still remains unclear. Supported by the DFG (SFG 4: Gl).