Hyalophysa

Hyalophysa Bradbury, 1966 (ref. ID; 2013)

Class Kinetofragminophora: Subclass Hypostomata: Order Apostomatida: Suborder Apostomatina (ref. ID; 2013)

[ref. ID; 2013]
Trophont; In moult of freshwater shrimp Palaemonetes paludosus and crayfish Cambarrus. Body twisted but pyriform in shape. There are 9 rows of somatic cilia which spiral dextrally down the body from anterior to posterior. Eight rows originate at or near the apex but kinety nine originates near rosette located in middle third of body. Anterior ventral surface flattened and contains scattered clumps of two or three cilia. Oral ciliature consists of 3 short ciliary rows left and posterior to rosette. Contractile vacuole without canal. Macronucleus elongate, situated just beneath midventral surface.
Phoront; Cyst with short peduncle attached to crustacea.
Quote; Colin R. Curds "British and other freshwater ciliated protozoa Part I Ciliophora: Kinetofragminophora" Cambridge University Press, 1982 (ref. ID; 2013)

Hyalophysa chattoni (ref. ID; 191, 4236, 4297, 4378, 4904)

Hyalophysa chattoni (ref. ID; 191, 4236, 4297, 4378, 4904)

Descriptions

Tomite: The Hyalophysa tomite is broad and flattened, slightly cupped ventrally convex dorsally (the average length and width is 45.6x24.4 um, n=41). After excystation, tomites swim quickly in helices in a relatively straight course. During experimental infetations clouds of tomites had to be used in order to observe many tomites settling. Due to this large concentration of tomites in a confined area with the host, the ability of the tomites to seek a host or the presence of any attraction of tomites to their host could not be determined. When tomites made contact with shrimp, they randomly explored the host's entire surface, crawling on their in ventral ciliary fields, and eventually accumulated on the antennal scales, around the eyestalks, under the carapace, and under the telson. Tomites about to settle slowed their crawling and selected sites for encystment. Once selected, individual tomites might crawl over a site for 30 min before swimming away or settling (i.e. the cessation of all movement). Periodically, tomites successively made two or three quick 180 degrees counterclockwise turns while crawling and repeated this crawling and turning pattern until they settled. Occasionally tomites would settle abruptly without this turning behavior. Tomites are gregarious and settle, squeezing next to encysted tomites, adjusting their position to fit between the earlier settlers. When a tomite settled in an unusually location, such as on the dorsal carapace, it was soon surrounded by tomites seemingly attracted to the central pioneer. Solitary phoronts were uncommon. (ref. ID; 4236)

Phoront: The encysted tomite (phoront) is attached to the host's exoskeleton by short peduncle. The phoront's average length and width (45.3x22.1 um, n=60) were smaller than the species on the west coast (79x42 um). The infraciliature of all recently encysted tomites (less than 1.5 hr) remained nearly identical to that of the swimming tomite, except that as the ciliate acquired a cylindrical shape, the ventral surface between kinety 9 (K-9) and K-1 was reduced. The first step in dedifferentiation was the disappearance of the two let rows of kinetosomes in falciform field 9 (FF9), leaving a gap between FF8 and FF9. The anterior end of FF9 curved and ended at K-2 near the end of FF8. Next, the ogival field (a large ventral field of cilia), diminishes. Kinetosomes disappear in a wave from the field's posterior-right margin proceeding anteriorly and to the left. Often a comma-shaped remnant persisted before reducing to a few kinetosomes and then completely vanishing. The reduction of the ogvial field and FF9 occurred within a short period of one another. A few organisms showed FF9 reduction only, but the reverse was never seen, indicating that FF9 reduces first. During this dedifferentiation from the tomite, the somatic kineties straightened and became meridional. Dedifferentiation was completed after the total loss of the ogvial field, and the phoront was now termed the "meridional phoront". Kineties X, Y, and Z of the "meridional phoront" have shortened slightly, the anterior row of kinetosome remains straight and the lateral canal paralleling it appears as two fine lines representing a tube as viewed in optical section. Forty-eight hours after settling, most (83%) of the encysted tomites had changed to the meridional stage at which they remain until they receive a cue from their host to begin metamorphosis to the trophont. (ref. ID; 4236)

Metamorphosis to the trophont: Protargol impregnation has confirmed earlier accounts of Hyalophysa's metamorphosis based on Chatton-Lwoff impregnations and has added information about structures invisible by the latter technique including the lateral canal, the anterior row so kinetosomes, and the characteristic rosette (a hollow cylindrical organelle subdivided by radial septa and with a central tuft of cilia). The metomorphosis to the trophont is a continuous process though for a convenient account of the events it was arbitrarily divided into four stages. (ref. ID; 4236)

Stage 1. The lateral canal lengthens to the anterior ends of kineties X, Y, and Z, then sinks into the cytoplasm and disappears. Concurrently, the posterior end of FF9 deviates to the right, away from FF8.
Stage 2. The posterior end of the lateral canal remains stationary while the anterior end is deflected as the tip of FF9 moves towards the right. The two lines representing the canal appear to separate at the canal's anterior end; the canal's posterior end does not separate but descends into the cytoplasm and disappears between K-9 and kineties X, Y, and Z. The lateral canal's anterior end apparently remains at the surface and posterior end sinks into the cytoplasm, The expanded area inside the canal is the argentophilic region that represents the developing cytostome visible in Chatton-Lwoff preparations. During the movements of the lateral canal, the anterior row of kinetosomes moved right and posteriorly with the canal into the indentation of K-1 and K-2 that formed as the cytostome enlarged. Now fine fibers directed towards the extended cytostome connect to the anterior row of kinetosomes.
Stage 3. The enlarging cytostome extends from the midventral surface dorsally around the phoront's right side. In delicate protargol preparations of this stage and of stage 2 and 4, a faint line of silver deposition marks the boundary of the extended cytostome. The anterior row of kinetosomes, migrating at the distal end of the extended cytostome, is now on the dorsal surface in the indentation of kineties 1, 2, and 3. The rosette shifted from its previous location above K-9 and is now midventral above kineties X, Y, and Z, where pairs of kinetosomes from FF9 are dispersing.
Stage 4. (the "encysted trophont" stage). The extended cytostome wraps completely around the organism so that its distal end (near the anterior row of kinetosomes) now appears posteriorly on the phoront's left-ventral surface. The distal end of the extended cytostome did not clearly impregnate with protargol as it had in stages 2 and 3. Chatton-Lwoff impregnations of the trophont indicate that the cytostome extends to the indentation of kineties 1, 2, and 3. The anterior row of kinetosomes is now perpendicular to the long axis of the body. The kinetosomes of the anterior row are impregnated heavily, spaced further apart, and appear to be in two rows. The fine fibers connected to these kinetosomes descend into the cytoplasm and the kinetosomes themselves are slightly deeper in the cytoplasm. All of the organism's somatic kineties are spiraled, and FF9 is completely dispersed into a scattered field of kinetosomes pairs. The short kinety A appears on the ventral surface. Its origin is unclear though may be the posterior tail of FF9. (ref. ID; 4236)