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Macronuclear Changes in a Strain of Blepharisma undulans during the Divisional Cycle *
Author(s) -
HELSON LAWRENCE,
PECORA PAULINE,
HIRSHFIELD HENRY I.
Publication year - 1959
Publication title -
the journal of protozoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.067
H-Index - 77
eISSN - 1550-7408
pISSN - 0022-3921
DOI - 10.1111/j.1550-7408.1959.tb03939.x
Subject(s) - macronucleus , interphase , elongation , strain (injury) , cytoplasm , condensation , biophysics , biology , phase (matter) , chemistry , microbiology and biotechnology , ciliate , genetics , anatomy , physics , materials science , organic chemistry , ultimate tensile strength , thermodynamics , metallurgy
SYNOPSIS. Specimens of Blepharisma undulans were transferred from young clone cultures to a rotocompressor with 3 mm 3 of culture medium. The organisms were slightly compressed and photographed at various intervals with dark field illumination. The sequence of macronuclear and cytoplasmic changes was compared with similarly followed Feulgen preparations. The cycle falls into several phases: ( 1 ) an interphase (12–24 hr.) in which the organism increases in size while cytoplasmic and macronuclear appearances remain unchanged. During this phase, the macronucleus consists of 3 to 5 nodes of various sizes connected by strands. ( 2 ) a pre‐condensation phase (1 hr.) in which a new posterior peristome and cytopyge appear without visible macronuclear change. ( 3 ) a condensation phase (10–20 min.) in which the macronuclear nodes coalesce into a round mass without dissolution of the central nodes or strands. ( 4 ) a postcondensation phase (1 hr.) characterized by: (a) elongation of the condensed macronucleus into a rod‐like shape followed by typical nodal formation; or (b) elongation of the condensed macronucleus into a form resembling the letter “J”, followed by nodal formation, and resulting in a double row of nodes in one daughter and a single row in the other. Separation occurs at this time, initiating the new interphase. The development of the j‐form macronucleus. the lack of obliteration of the central nodes, and the characteristic interphase condition distinguish this strain of B. undulans from others described elsewhere.