Pré-visualização28 páginas
spongy appearance (i.e., the spongiome), found in the vicinity of the contractile vacuole , function- ing to collect fluid for elimination. Springborsten : see Saltatorial Cilia . Stalk : term broadly used for any kind of cylindri- cal and generally tubular supporting structure, either totally non-living or with a non-living sheath or annulus , running from the posterior end of a ciliate\u2019s body to a point of fixation on the underlying substratum; typically found in attached, sedentary or sessile forms or stages, with or without involvement of a lorica, serving as an attachment or holdfast organelle ; may be of varying length, composition, and origin; produced with involvement of secretory ampullae , kineto- somes , and/or pellicular pores ; may be contractile with a spasmoneme or non-contractile; ramified in some groups, associated with colonial organi- zation of the supported zooids ; most commonly 54 2. Glossary of Terms and Concepts Useful in Ciliate Systematics known in chonotrichs , suctorians , and peritrichs , but undoubtedly is a non-homologous structure in these diverse taxonomic groups; see Peduncle (St, Fig. 2.11B, 2.11C). Statocyst : see Concrement Vacuole and Müller\u2019s Vesicle . Statolith : see Concrement Vacuole and Müller\u2019s Vesicle . Stentorin : \u201cblue\u201d cytoplasmic pigment distributed in pigmentocysts and appearing in longitudinal rows in certain species of the heterotrich Stentor . Stereocilum (pl. Stereocilia ): see Clavate Cilium . Stichodyad : type of paroral whose infraciliature is composed of dikinetids so oriented that each is perpendicular to the anteroposterior axis of the paroral ; these kinetosomes are often arranged in a zigzag pattern with only the outer kinetosomes being ciliferous ; common condition in oligohy- menophoreans ; see Haplokinety , Stichomonad . Stichomonad : type of paroral whose infraciliature is composed of a single file or line of identically oriented kinetosomes ; the characteristic condition found in many spirotrichs ; see Diplostichomonad , Stichodyad . Stock : now seldom-used term referring to any named or numbered clone that is maintained in culture separately from other such isolates. Stomatogenesis : literally \u201cmouth-formation\u201d; in the broadest sense, this dynamic phenomenon embraces neoformation or replacement of all oral structures and infrastructures and any associated openings, depressions or cavities in both the proter and opisthe , typically prior to and during binary fission ; major kinds or modes are now recognized (see Apokinetal , Buccokinetal , Mixokinetal, Parakinetal , and Telokinetal ), under which the names of older descriptive categories are gener- ally listed, as synonyms; oral replacement , a stomatogenic phenomenon that may occur peri- odically, refers to the in situ remodeling of the parental oral structures or their total substitution by new organelles, because of the partial or com- plete dedifferentiation or resportion of the former ones; reversible microstome-macrostome transforma- tion , a special kind of oral replacement, involves the growth and/or replacement of a small oral apparatus with a greatly enlarged one or vice versa (e.g., in some species of Tetrahymena ); see Somatogenesis (Fig. 2.11D). Stomatogenic Field : general term for the group of kinetosomes , non-ciliferous throughout most of the process, actively involved \u2013 as the anlage \u2013 in the production of new oral ciliature by any of the described modes of stomatogenesis ; see Anarchic Field , Germinal Row , and Scutica (SF, Fig. 2.11Dg). Stomatogenic Kinety (pl. Kineties ): see Kinety Number 1 and Parakinetal ( stomatogenesis ) (SK, Fig. 2.11Dd). Stomatogenous Meridian : an older term for sto- matogenic kinety . Strain : a named clone of a particular species of cil- iate that usually differs in minor ways (e.g. genetic, phenotypic, physiological) from other strains. Stria (pl. Striae ): a beaded, longitudinal cytoplasmic strand found beneath the perilemma in the oral polyki- netids of some spirotrichs , especially tintinnids . Striated Bands : name for a (micro)fibrillar system discovered to lie just below the epiplasm in some ciliates (e.g., Paramecium ). Strobilation : kind of multiple fission in which successive tomites or buds are fully or partially separated or pinched off, sometimes within the confines of a cyst and usually resulting in a tem- porary linear chain of small individuals requiring subsequent metamorphosis to regain the form typi- cal of the normal trophont stage of the life cycle; see Catenoid Colony (Fig. 2.8Ba). Structural Conservatism Hypothesis : mainte- nance (i.e., conservation) of a structure through time is inversely related to the level of its biologi- cal organization; in the evolution of ciliates, then, among the most stable and most conservative taxonomic characters would be those involving unit organelles , ultrastructures at a relatively low organizational level (e.g., the various microtubular ribbons and kinetodesma associated with monoki- netids and dikinetids). Structural Guidance, Principle of : positioning and orientation of newly arising organelles (e.g., kineto- somes on the surface) under the localized influence of nearby pre-existing structures; see Cytotaxis . Glossary 55 Style : see Stylet . Stylet : variously used, but generally as a synonym of podite . Stylus : see Stylet . Subkinetal Microtubules : one or more microtubu- lar ribbons running under the proximal ends of kine- tosomes in phyllopharyngeans (e.g., Brooklynella ); compare to Basal Microtubules . Subpellicular Microtubules : microtubules , single or in ribbons, in or just under the pellicle and cours- ing along parallel to the outer surface of the cell; originate either independently from kinetosomes (e.g., longitudinal microtubules ) or may be exten- sions of transverse or postciliary microtubules . Sucker : variously used, but generally for the cup- shaped concavity forming the often non-homologous thigmotactic area or adhesive organelle in scattered species belonging to quite different taxa (e.g., astomes , clevelandellids , licnophorids , peritrichs , thigmotrichs ); also used to denote the sucking tube of rhynchodids; may be rich in fibrils, polysac- charide plaques or thigmotactic cilia ; a rare syno- nym, for protozoa, is acetabulum; see Attachment Organelle (S, Fig. 2.9B). Sucking Tentacle : see Suctorial Tentacle . Sucking Tube : apically located, complex septate structure composed of microtubular ribbons , the phyllae , and serving as the ingestatory apparatus of rhynchodids and grossglockneriid colpodeans (Fig. 2.10f). Suctorial Organelle : see Suctorial Tentacle . Suctorial Tentacle : extensible and retractable tubular extension of the body of suctorians , con- taining a complex array (set or sets) of longitu- dinally arranged microtubular ribbons or phyllae and equipped both with haptocysts at its often capitate tip and vesicles functioning in formation of food vacuolar membrane; the tentacle serves for prey capture but is also the organism\u2019s ingestatory apparatus, analogous, if not homologous, with the cytostome-cytopharyngeal complex of other phyllo- pharyngeans ; ranging from one in number to many, their grouping in fascicles on the body, whether on actinophores or not, is often of taxonomic sig- nificance; the larval or bud stages in suctorian life cycles possess none, as a rule; a type of extremely short, non-extensible tentacle, the endosprit , is known in several families (e.g., Cyathodinium ) (SuT, Figs. 2.8i, 2.11Cd; 2.10a\u20132.10e). Supernumerary Kinetosomes : apparently \u201cextra\u201d ciliferous or barren kinetosomes observed in vari- ous instances, in more than one stage in the life cycle, in differing but specific locations on the