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M Cachon

Publications and source records attributed to M Cachon.

8 recordsLinked to original sources
PubMed1997

Isolation of the major basic nuclear protein and its localization on chromosomes of the dinoflagellate, Oxyrrhis marina.

Basic nuclear proteins were extracted from isolated nuclei of Oxyrrhis marina. The HPLC pattern of the extract showed a single major peak, which consisted of a major band with an apparent molecular mass of 23 kDa on an SDS-PAGE gel. We designated this protein as Np23 because of its apparent molecular mass. The amino acid composition of this protein revealed its extremely basic nature with a high lysine content. Polyclonal antibodies were raised against Np23. Immunofluorescence microscopy showed that Np23 was localized within the nucleus of dividing and non-dividing cells as well, and immuno-electron microscopy showed that the protein was localized only on chromosomes. These data established that Np23 is the major basic chromosome protein of Oxyrrhis marina.

Animals↗
PubMed1988

Swimming behaviour of the unicellular biflagellate Oxyrrhis marina: in vivo and in vitro movement of the two flagella.

The movement of the 2 flagella of Oxyrrhis marina was examined with respect to their individual waveforms and the swimming behavior of the organism. The longitudinal flagella propagated helicoidal waves whose amplitude decreased toward the tip of th 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" behavior of sea urchin spermatozoa. Isolated flagella were ATA-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 in motile behavior reflect regulations of flagellar movement which were not destroyed by the isolation procedure and may be indicative of regulation by accessory structures.

Adenosine Triphosphate↗
PubMed1981

Movement by non-actin filament mechanisms.

Non-actin contractile MFS exist in Protozoa. Their chemical constitution is partially known. They are ATP-independent, but their various physiological characters can be ultrastructurally grouped into two types: either, as it is the case for actin, they are closely associated to the endoplasmic reticulum apparatus, or they form myonemal bundles which are not related to any other organelle.

Actins↗
PubMed1977

Observations on the mitosis and on the chromosome evolution during the lifecycle of Oodinium, a parasitic dinoflagellate.

The life cycle of the dinoflagellate Oodinium alternates between an ectoparasitic trophic phase and a phase of multiplication as free-living flagellates. The nucleus of the young ectoparasite has rod-like chromosomes similar to those of free-living dinoflagellates. As growth of the trophout proceeds the nucleus becomes increasingly homogeneous. When Oodinium leaves its host, nuclear reorganization processes occur rapidly; they correspond to a peculiar prophase of the first sporogenetic division. The following division stages are similar. A conspicuous fusorial system appears between two archoplasmic areas which are responsible for daughter-chromosome segregation. The nuclear envelope remains intact while the fusorial microtubules are attached at distinct, kinetochore-like structures onto the nucleus. As the chromosomes become more condensed the kinetochore-like formations disappear.

Animals↗
PubMed1977

Movement generated by interactions between the dense material at the ends of microtubles and non-actin-containing microfilaments in Sticholonche zanclea.

Axopods of the planktonic protozoan, Sticholonche, are used as oars to propel the organism through seawater. Within each axopod is an orgainzed array of microtubules which inserts into a dense material that assumes the form of the head of a hip joint. This material, in turn, articulates on the surface of the nucleus. Microfilaments, 20-30 A in diameter, connect the dense material associated with the microtubules to the surface of the nucleus, and they move the axopod by their contractions. The active phase of the movement may take as little as about 0.04 s and the recovery phase may take between 0.2 and 0.4 s. The microfilaments are not actin, as based on: (a) their small diameter, (b) the lack of decoration with heavy meromyosin, and (c) their ability to coil, spiral or fold during contraction. By the use of Thorotrast, we were able to demonstrate that the cell surface is deeply infolded, extending all the way to the hip joint. Here, there is a specialized membrane system that resembles the diad in skeletal muscle. From cytochemical tests and the use of ionophores and chelators, there is some evidence that the motile process may be controlled by calcium. This study demonstrates that, in at least one system, microtubules can be moves by contractile microfilaments attached to the dense material at there tips.

Animals↗