Phyllis Clarke Bradbury

Ultrastructure of the dinoflagellate Polykrikos: II. The nucleus and its connections to the flagellar apparatus

Electron microscopy of the colonial dinoflagellate Polykrikos kofoidi revealed a nuclear cortex formed of two electron-dense cortical layers directly beneath the nuclear envelope. Nuclear pores were confined to vesicular outpocketings of the nuclear envelope over circular discontinuities in the cortical layers. A conspicuous fibrous ribbon extended from the nucleus to the flagellar apparatus of each zooid. The ribbons resembled in their structure and position the attractophores of termite flagellates. Each flagellar apparatus consisted of two flagella, two elongate axial kinetosomes, an oblique kinetosome, and two roots of markedly different periodicities.

The fine structure of a parasitic ciliate Terebrospira during ingestion of the exoskeleton of a shrimp Palaemonetes

The ciliated protozoan, Terebrospira chattoni, invades the exoskeleton of the shrimp, Palaemonetes pugio, eating out long galleries parallel to the surface of the exoskeleton. Solubilization of the exoskeleton occurs around an area of the elaborately infolded surface membrane at the anterior of the organism. Dissolved products of the digestion of the exoskeleton are taken into the body by the formation of coated vesicles at pores in the membrane. The surface membrane that is taken in by pinocytosis is apparently recycled by the introduction into the membrane of organelles implicated in membrane recycling in other ciliates. Acid phosphatase can be demonstrated on the surface membrane as well as in the endocuticle around the organism.

The feeding apparatus of a chitinivorous ciliate

The chitinivorous ciliate Ascophrys, an ectosymbiont of the shrimp Palaemon serratus, is enclosed by a thick cyst wall except for a ventral hiatus exposing a circular area of exoskeleton to the interior of the cyst. The exoskeleton underlying the cyst wall remains intact, but the circular area of exoskeleton is dissolved enzymatically and ingested. The feeding ciliate forms a cavity in the exoskeleton into which it sinks. Its complex oral apparatus resembles a pump encircled by cytoplasm containing Golgi and high concentrations of coated vesicles that join pellicular pores between cilia. The ingestive apparatus is formed of microtubular lamellae that originate in the midplane of the body, descend toward a coated membrane on the surface, and ascend again as a lamellar lining to a complex food tube that ends in the middle of the body surrounded by food vacuoles. The cytoplasm enclosed between the descending lamellae and the food tube is crowded with membrane organelles that recycle as food vacuole membranes at the coated membrane. We hypothesize that vacuoles containing dissolved exoskeleton are drawn up into the oral tube and are released into the cytoplasm at the terminus of the tube, where their contents are concentrated and excess vacuolar membrane collapsed into membrane organelles.

Comparative Studies on a New Brackish Water Euplotes, E. parawoodruffi n. sp., and a Redescription of Euplotes woodruffiGaw, 1939 (Ciliophora; Hypotrichida)

Summary The morphology, nuclear apparatus, infraciliature, and silverline system of two populations of the Euplotes woodruffi-complex, one from brackish water off Pamlico Sound, North Carolina (USA), and the other from a freshwater pond in Qingdao (P.R. China), have been examined in vivo and with silver nitrate and protargol impregnations. A comparison of the two forms reveals marked differences in structure sufficient to separate the two morphotypes into two species. Euplotes parawoodruffi n. sp. (syngen 1 of E. woodruffi) is characterized by a strongly arched dorsum, regular double-eurystomas type silverline system, an adoral zone of ca. 80 membranelles extending over 4/5 of the cell length; 9 frontoventral, 2 marginal, and 2 caudal cirri; marine/brackish biotope; macronucleus irregularly T-shaped. Its T-shaped macronucleus with a short right arm differs from that of E. woodruffi, in which the right arm is longer than the left. The general body shape of E. parawoodruffi, broad anteriorly and tapering posteriad, differs from the ovoid shape of E. woodruffi. Its domed dorsum without longitudinal grooves differs from the flattened dorsum with shallow grooves of E. woodruffi. The presence of a longer AZM formed of consistently more membranelles and the absence of a pre-oral pouch (an invagination on the dorsal wall of the buccal field anterior to the cytostome, always present in E. woodruffi) further separates E. parawoodruffi from the latter.

A Redescription of Gymnodinioides caridinae (Miyashita 1933) from Palaemonetes sinensis (Sollaud 1911) in the Songhua River

ABSTRACT The freshwater exuviotrophic apostome, Gymnodinioides caridinae, was discovered in the Songhua River where it flows through Harbin, Peoples Republic of China. This apostome species thus has been found in Japan, China, and Belgium, but on different species of shrimp in each place. Protargol impregnations of Gymnodinioides caridinae on Palaemonetes sinensis (Sollaud) confirmed most of Miyashitas original description of the infraciliature and may explain the structure he interpreted as an accessory contractile vacuolar canal.

Redescription of Ellobiophrya brevipes (Laird, 1959) N. Comb. (Ciliophora, Peritrichia) and the Fine Structure of its Pellicle and Cinctum

ABSTRACT. A species of peritrich that attaches to gills of the skate, Raja erinacea, was identified by its original describer as a member of Caliperia, a genus characterized by having a noncontractile skeletal rod within the arms of its cinctum and by not having the cinctal arms bonded to one another at their tips. Our observations of the living ciliates confirmed by protargol impregnation and electron microscopy revealed that their cinctal arms are linked by a bouton and that the cytoskeletal structure within them has the fine structure of a myoneme. These characteristics place this peritrich unequivocally in the genus Ellobiophrya and it is thus renamed Ellobiophrya brevipes (Laird, 1959) n. comb. Clumps of epithelial cells clasped by the cincta of E. brevipes show damage at their bases but not on their luminal surfaces. The known species of Ellobiophrya are compared for significant structural differences that separate species of this genus.

Stomatogenesis during the formation of the tomite of Hyalophysa chattoni (Hymenostomatida: Ciliophora)

Summary The functioning oral apparatus of the feeding stage of Hyalophysa chattoni Bradbury, 1966 , arises from pre-existing structures in the tomite that change their form and position during a metamorphosis to the trophont. These structures are the relic of a microstome oral apparatus in the non-feeding tomite. Their origin has been studied during tomitogenesis using Shis protargol method. In general, this method of silver impregnation confirms the earlier description of tomitogenesis by Chatton and Lwoff, but it reveals significant details concerning the fate of certain transient kineties that form structures which later contribute to the functioning cytostome. Before palintomy, all the kineties of the encysted tomont straighten and become meridional. Nine somatic kineties − x , y , and z (the “oral” kineties), and kinety a , thirteen kineties altogether extend approximately from pole to pole. Kinety a parallels K1. After the first division of the tomont, the kinetosomes of K a multiply in a broad band to the left of the kinety. During subsequent divisions, the kinetosomes in the band assemble into three meridional, transient kineties — K a , K b , and K c . After the last division, each daughter has nine meridional somatic kineties spaced around the body and six meridional ventral kineties crowded between K1 and K9. During tomitogenesis, all the ventral kineties shorten; only the posterior halves of x , y , and z are retained. Kinety x extends a little farther anteriad than y and z . This extension separates from the rest of x and sinks into the cytoplasm where it forms the tuft of cilia on the proximal wall of the developing rosette. The shortened a , b , and c migrate left, anterior to x , y , and z . Both extremities of K a disappear, and the remaining kinetosomes proliferate to form the ogival field, a mid-ventral patch of closely set cilia found only in the tomite. Kinety b disappears leaving behind a barren haplokinety near the apex of the tomite. Kinety c disappears completely, but under the pellicle in the place where it disappears, a microtubule-lined canal, the cytopharynx of the microstome, parallels the ogival field and the haplokinety to the apex of the organism. The last step in microstome formation is the doubling of the anterior portion of kinety 8 and the quadrupling of the anterior fragment of kinety 9 to produce falciform fields 8 and 9 (FF8, FF9), the equivalent of oral polykineties 2 and 1 in other hymenostomes. The oral apparatus of the microstome consists of an anterior haplokinety (paroral), three polykineties (FF9, FF8, and the ogival field), and the cytopharynx. Except for the falciform fields, all these structures originate from kinety a . The falciform fields originate as proliferations of the ends of somatic kineties 8 and 9, indicating that, at least in part, apostomes have telokinetal stomatogenesis. The origin of K a is revealed during the formation of the macrostome. After the tomite encysts on the host, the ogival field disappears completely within hours. When metamorphosis to the trophont begins, the barren haplokinety and the lateral canal migrate posteriad over the ventral surface and then dorsad, establishing the limits of the extended cytostome, a greatly enlarged surface on the trophont. The haplokinety then disappears, and the microtubules of the cytopharynx remain as ribs under the extended cytostome. Falciform field 8 remains unchanged, still a dikinety. The kinetosomal rows of FF9 become disorganized, and paired kinetosomes move over the anterior ventral surface to form the anterior field of scattered kinetosomes characteristic of Hyalophysa . The posterior portion of FF9, losing kinetosomes as it goes, moves across the mid-ventral surface and stops at the left of K1 where K1 makes a sharp angle to parallel the extended cytostome. There the last remnant of FF9 remains as K a in the trophont. It does not function as oral ciliature. It is an anlage for part of new microstomes in daughter cells that will be formed days hence. The microstomes of these daughter cells will be completed at that time by the proliferation of kineties 8 and 9 to form FF8 and FF9. Thus, in Hyalophysa the tomites microstome is formed in part by a derivative of K9 (K a ) from the preceding generation and completed by proliferation of K8 and K9 from the present generation. Stomatogenesis is telokinetal, but modified by a somatic derivative from one generation carried over to the next.

Conjugation in Hyalophysa chattoni Bradbury (Apostomatida): An adaptation to a symbiotic life cycle

Hyalophysa chattoni, borne as an encysted phoront on a crustaceans exoskeleton, metamorphoses to the trophont during the hosts premolt. After the molt within 15min to 2h conjugants with food vacuoles appear in the exuvium, swimming along with the trophonts. Starvation in other ciliates usually precedes conjugation, but food vacuoles in conjugants do not preclude starvation. Only after ingestion and dehydration of vacuoles ceases, does digestion of exuvial fluid begin. Conjugants resorb their feeding apparatus as they fuse. A single imperforate membrane from each partner forms the junction membrane. In a reproductive cyst conjugants divide synchronously, but now the junction membrane is interrupted by pores and channels. After the last division the daughters undergo meiosis--two meiotic divisions and one mitotic division yielding two prokarya as they simultaneously differentiate into tomites. After fertilization, pairs separate and the synkaryon divides once into a macronuclear anlage and a micronucleus. Exconjugants leave the cyst and seek a host. The parental macronucleus remains active until the phoront stage when the anlage develops. Owing to random association of micronuclei during meiosis, Hyalophysas exconjugants are more genetically diverse than exconjugants from conventional patterns of conjugation.