ISSN:0248-4900    

DOI:10.1016/0248-4900(88)90049-4

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Summary—The movement of the 2 flagella ofOxyrrhis marinawas examined with respect to their individual waveforms and the swimming behaviour of the organism. The longitudinal flagella propagated helicoidal waves whose amplitude decreased toward the tip of the flagellum. Their beat frequencies were 50–60 Hz. The transverse flagella beat helicoidally within a furrow. Sudden changes in the direction of the cell trajectories were generated by transient arrests of the longitudinal flagellum beat, which were accompanied by a switch from the backward orientation to a forward one. This sweeping motion generated the rotation of the cell body. Ca2+ions highly stimulated the frequencies of this arrest response, which compared to the “walking‐stick” behaviour of sea urchin spermatozoa.Isolated flagella were ATP‐reactivated after detergent treatment. They exhibited 2 types of motion within the same experimental conditions. A progressive helicoidal motion was generated upon longitudinal flagellum reactivation, whereas a rolling motion with little progression characterized transverse flagellum reactivation. The differences motile behaviour reflect regulations of flagellar movement which were not destroyed by the isolation procedure and may be indicative of regulation of accessory

ISSN:0248-4900    

DOI:10.1016/0248-4900(88)90050-0

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Summary—LivingCrithidia oncopelticells swim through their environment by means of tip‐to‐base waves on their single flagellum. The cells are able to re‐orient themselves by using a short burst of asymmetrical base‐to‐tip waves. All points on a flagellum are capable of initiating waves. Placing a population of cells in a medium of high viscosity initially produces a large number of organisms beating in the reverse mode. An individual cell has a random “switching” behaviour. Viscosity affects the frequency of forward and reverse waves in different ways. The concentration of free Ca++ions determines the direction of wave propagation in reactivated axonemes. Calmodulin may play a role in mediating the Ca++dependence of

ISSN:0248-4900    

DOI:10.1016/0248-4900(88)90051-2

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Summary—Ciliary movement is generated in the axoneme by the unidirectional sliding of the outer doublets of microtubules produced by the adenosine triphosphate (ATP)‐energized dynein arms. It is composed of an effective stroke phase and a passive recovery stroke phase. Two parameters are modulated to determine the swimming characteristics of the cell (speed and direction): (i) beat frequency; (ii) direction of the effective stroke.They are linked to the internal Ca++level and to the membrane potential. The membrane governs the internal Ca++level by regulating Ca++influx and efflux. It contains voltage‐sensitive Ca++channels through which is passive Ca++influx, driven by the electrochemical gradient, occurs during step depolarization. The rise of the Ca++level, up to 6.10−7M triggers ciliary reversal and enhances beat frequency. Ca++is extruded from cilia by active transport. Ca++also activities a multistep enzymatic process, the first component of which is a membrane calmodulin‐dependent guanylate cyclase. cGMP interacts with Ca++to modulate the parameters of the ciliary beat. The phosphorylation‐ dephosphorylation cycle of axoneme and membrane proteins seems to play a major role in controlling ciliary movement.Hyperpolarization of the membrane enhances beat frequency by an unknown mechanism. It could be a modification of the ratio of axonemal bound Ca++and Mg++, or activation by cyclic adenosine monophosphate (cAMP) produced by a membrane adenylate cyclase.The ciliary membrane behaves as a receptor able to detect modifications of external parameters, and as a transductor transmitting the detected signal by second or third messengers toward the interior of the cilia. These messengers, acting at different levels, modulat the parameters of the mechanism that generates cilia

ISSN:0248-4900    

DOI:10.1016/0248-4900(88)90052-4

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Summary—The ciliary beat and cell motility ofDunaliella, a biflagellate unicellular green alga, have been studied by means of computer analysis of high‐speed microcinematography and laser doppler velocimetry. Lindane was found rapidly to inhibit cell velocity in less than 5 min and in a dose‐related manner. After the initialp 5‐min period, inhibition remained nearly stable for at least 3 hr.The waveform of the ciliary beat was not uniformly affected by lindane and only the effective stroke was greatly slowed down. The recovery stroke was not significantly modified, and the general form of the wave did not seem to be altered. Bending parameters automatically measured from high‐speed movies that lindane induced a considerable lengthening of the initiation phase of wave propagation. Since lindane interacts specifically with calcium transport and can induce an increase in cytoplasmic calcium, the strong effect of lindane on cilliary beat is probably correlated with a modification of the calcium balance of the cell. These results support the hypothesis of a control of bend initiation b

ISSN:0248-4900    

DOI:10.1016/0248-4900(88)90053-6

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Chondrichthyes posses an evolved type of spermatozoa. Their flagellar apparatus is characterized by the presence of flagellar roots which form the axis of the midpiece, and the existence of one or two lateral elements associated with the axoneme, Osteichthyes, mainly teleosteans, show a great diversity of spermatic forms. The primitive spermatozoon with a 9+2 pattern flagellum is common. The primitive spermatozoon has evolved along different lines. The spermatic diversity which results from this is mainly evident in the structure of the flagellar apparatus. In the animal kingdom the primitive spermatozoon with a 9+2 pattern flagellum, present in primitive metazoa, is retained in phyla where external fertilization is maintained. The main evolutionary tendencies – elongation, aflagellarity or biflagellarity – are generally connected with the acquisition of internal fertilization. These evolutionary tendencies are found in teleosteans. It is not Possible to link aflagellarity or biflagellarity of the gamete in certain fishes to this method of fertilization. Only the elongation of the spermatozoon is connnected, in certain cases, with interanl fertilization, but this cannot be taken as gene

ISSN:0248-4900    

DOI:10.1016/0248-4900(88)90054-8

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Summary—Oxyrrhis marina, like all dinoflagellates, possesses one transverse and one longitudinal flagellum, which show structural differences.The transverse flagellum contains a small fibre, 20 nm in diameter, associated with doublet no.7, whereas the longitudinal flagellum is substantially by a large (200–300 nm) hollows structure closely resembling the paraflagellar rod described by several authors in kinetoplastidae and in euglenoids. This structure is made up of a hemicylindrical network of filaments which are often linked on one side to the outer doublet no. 4, and on the other side to a dense plate. Another thinner filamentous network closes this hemicyclinder. In cross‐section, the wall of this structure is made up of 8 filaments 2–4 nm in diameter that show a thicker periodic structure. In longitudinal section the same filaments appear arranged in periodic rhombus meshes or a helicoidal pattern, depending on the orientation of the section relative to the

ISSN:0248-4900    

DOI:10.1016/0248-4900(88)90055-X

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

ISSN:0248-4900    

DOI:10.1016/0248-4900(88)90056-1

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Summary—Ciliated cells are characterized by a highly organized cytoskeleton which is connected with the ciliary apparatus. The organization of microtubules, microfilaments, and cytokeratin filaments is described and the relationships of each network with the ciliary apparatus are emphasized. Possible functions of such a complex cytoskeleton are discusse

ISSN:0248-4900    

DOI:10.1016/0248-4900(88)90057-3

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Summary—The different steps of ciliogenesis occurring in quail oviduct were compared to the ciliogenesis pattern described in other metazoan species.Centrioles are generated according to pathways that are found within the same cell: the centriolar and the acentriolar pathways. In the acentriolar pathway, centrioles are generated in the Golgi area, without contact with the preexisting centrioles of the centrosomes, and they migrate toward the apical membrane. The control of this polarized migration was studied by means of several drugs (colchicine, nocodazol, taxol, cytochalasin D, benzodiazepines) and immunocytochemistry.It was suggested that an actin‐myosin system was involved in the migration of centrioles, whereas labile microtubules were not necessary.Basal bodies must dock with plasma membrane or cytoplasmic vesicles for the initiation of axonemal microtubule polymerization. This signal is necessary even in the presence of ta

ISSN:0248-4900    

DOI:10.1016/0248-4900(88)90058-5

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY