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which can be considered lecto-
Holozoic : mode of nutrition or feeding in which 
particles or whole prey are ingested; for a contrast-
ing mode; see Saprozoic . 
Homokaryotic : fundamentally possessing but one 
kind of nucleus, neither a micronucleus nor a 
macronucleus; among the ciliates, this character-
istic was limited to Stephanopogon species, which 
are no longer considered to be ciliates; not to be 
confused with the amicronucleate condition. 
32 2. Glossary of Terms and Concepts Useful in Ciliate Systematics
Homologous : characters, traits, structures or 
organelles that resemble one another due solely 
to inheritance from a common ancestor; if such 
ancestry is unknown or unknowable, it may be 
inferred, keeping in mind the possibility of conver-
gent evolution and other such confounding factors; 
see Analogous . 
Homomerous Macronucleus (pl. Macronuclei ): 
 nucleus with no differentiation into zones contain-
ing differing DNA and RNA contents; essentially 
uniform staining capacity exhibited, except for 
heterochromatin granules and nucleoli; this is the 
type of macronucleus found in the great majority 
of ciliates; see Heteromerous Macronucleus
(Fig. 2.12).
Homonym : one of two or more names identical in 
orthography (spelling) applied to different organ-
isms or taxa; the earlier published name of two is 
the senior homonym and must prevail; the other is 
the junior homonym and must be replaced, unless 
it is a junior synonym; see Synonym . 
Homopolar Doublet : individual ciliate with two 
sets of mouthparts, separated by 180° at the ante-
rior end of the body; typically, a teratological and 
unstable condition. 
Homothetogenic Fission : type of division of a 
parental form in such a manner that there is a 
point-to-point correspondence (i.e., exhibition of 
the condition of homothety) between structures 
or “landmarks” in both filial products , the proter
and the opisthe ; generally transverse or perkinetal
fission ; to be contrasted with the symmetrogenic
or mirror-image fission of flagellates ( interkinetal
division) (Fig. 2.11A). 
Homothety : see Homothetogenic fission . 
Hook : see Attachment Organelle . 
Host : independent or so-called dominant member 
of a symbiotic pair, unless the relationship is a 
mutualism ; the dependent partner, the symbiont , 
lives in or on the host. 
Hydrogenosome : a cytoplasmic organelle derived 
from the ciliate mitochondrion ; it produces hydro-
gen and ATP, and may or may not have remnants 
of the mitochondrial cristae. 
Hyperparasitism : see Parasitism . 
Hypoapokinetal : apokinetal stomatogenesis in 
which the oral anlage develops or begins develop-
ment in a subsurface pouch or an “intracellular” 
tube; found in some spirotrichs (Fig. 2.11h). 
Hypostomial Frange : see Frange . 
Indicator Organism : an organism whose presence 
reflects a certain set of ecological or environmental 
conditions; used with respect to “pollution ecol-
ogy” studies; see Saprobity System . 
Infraciliary Lattice : branching filamentous tract 
or mat at the boundary of ectoplasm and endo-
plasm, running parallel to and not far from the 
surface of the organism’s body, but at a deeper level 
than that of either the epiplasm or the layer of 
striated bands (as known in Paramecium ). 
Infraciliature : assembly of all kinetosomes and 
associated microfibrillar or microfilamentous and 
microtubular structures, both somatic and oral in 
location; lying below the pellicle ; the argentophilic
nature of most such organelles and structures and 
their universality and stability make the infracilia-
ture an ideal system for study to gain significant 
information in areas of morphogenesis, evolution, 
and phylogeny, as well as in comparative systemat-
ics at all taxonomic levels (Fig. 2.4). 
Infundibulum (pl. Infundibula ): lower or inner 
or posterior part or section of the buccal cavity in 
certain ciliates, particularly peritrichs ; an often 
long, funnel-shaped tube or canal; may contain 
some of the oral ciliature and its infraciliature
(e.g., the oral polykinetids of peritrichs) (Inf, Fig. 
Ingestatory Apparatus (pl. Apparati ): see Oral
Apparatus . 
Inquiline : term often used for commensal organ-
isms living in a body cavity of some host and 
not obtaining nourishment directly from or at the 
expense of it; employed primarily for echinophilic 
ciliates essentially endemic in the digestive tract of 
their hosts (e.g., certain scuticociliates). 
Interkinetal : between the kineties; as a kind 
of division in protozoa; see Symmetrogenic 
Fission . 
Glossary 33
Intermeridional Connectives : apically located 
concentric silverlines encircling the anterior part 
of the body of certain ciliates (e.g., Tetrahymena ); 
probably argentophilic artifacts of some sort, but 
their constancy and invariate nature, make them of 
value taxonomically; see Circumoral Connective
(IC, Fig. 2.7e). 
Internal Budding : see Endogenous Budding . 
International Code of Zoological Nomenclature : 
 authoritative dicta regarding all nomenclatural 
matters for animals essentially to the level of 
familial taxa; assumed to include the protozoa, 
provisions of “the Code” affect systematics and 
classification to the obvious yet significant extent 
that nearly all taxonomic decisions ultimately 
require use of scientific names. 
Interstitial : living between, among, or in the 
interstices of sand grains or similar sediments; see 
Psammophilic . 
Intertelokinetal : telokinetal stomatogenesis in 
which the oral anlagen of kinetofragments are 
produced by proliferation of kinetosomes both at 
the ends and beside the ends of all somatic kineties ; 
thus, the number of oral kinetofragments exceeds 
the number of somatic kineties; found in some 
 vestibuliferian trichostomes . 
Intrabuccal Kinety (pl. Kineties ): a kinety
extending deep into the oral cavity of loxodid 
 karyorelicteans . 
Intraclonal Conjugation : conjugation within a 
clone , apparently pure for one mating type; some-
times referred to as selfing. 
Intracytoplasmic Pouch : temporary depression, 
cavity or “vacuole” in which the oral anlage appears 
during stomatogenesis ; found especially in entod-
iniomorphids , oligotrichs , and some hypotrichs ; 
see Hypoapokinetal (IcP, Fig. 2.11h, 2.11i). 
Intramacronuclear Microtubules : microtubules
that assemble inside the macronuclear envelope
during division by amitosis of the macronucleus ; 
considered to be the derived character for the 
Subphylum Intramacronucleata . 
Isoconjugants : conjugants of the same size; see 
Conjugation . 
Isogamonts : gamonts of the same size; see Gamonts . 
Isotomic : literally “equal parts”; see Fission . 
Kappa Particles : members of the bacterial groups, 
alpha-proteobacteria and gamma-proteobacteria, 
endosymbionts of Paramecium species; see Endo-
symbiont . 
Karyoklepty : literally “nuclear stealing”; a phenom-
enon in which a host ciliate captures the nuclei of its 
symbionts and uses these to maintain symbiont cyto-
plasm within the ciliate host’s cytoplasm; only demon-
strated so far in the litostome Myrionecta rubra . 
Karyokinesis : synonym of mitosis (i.e. the divi-
sion of the nucleus). 
Karyological Relict : organism that is presumed to 
be a remnant or direct and little-changed descend-
ant of an early or phylogenetically ancient group of 
ciliates, at least with respect to its nuclear condi-
tion or properties; particularly assumed to be the 
case for karyorelicteans with diploid, non-dividing 
macronuclei ; see also Macronuclear Evolution 
Hypothesis . 
Karyomere : see Heteromerous Macronucleus . 
Karyonide : clone bearing the descendants of one 
of the new macronuclei produced during nuclear 
differentiation following conjugation . 
Karyophore : strands or sheets of specialized and 
generally conspicuous fibers emanating from sub-
pellicular locations and surrounding