Endogenous Bud Formation in Histriculus vorax, a New Asexual Reproductive Process In the Hypotrichida

Abstract

SYNOPSIS. Histriculus vorax (Stokes) Corliss, a hypotrichous ciliate, has been separated from activated sludge and cultured monoxenically in the laboratory. The asexual life cycle has been observed and the stages of development photographed. There are large variations in shape and size of cells within clonal cultures. Both large (190–250 μ long) and small (70–140 μ long) cells are capable of normal asexual binary fission but only the large cells are able to grow endogenous buds, which, when mature, are extruded through the body wall of the mother cell. Newly deposited buds can either develop directly into an embryonic form, or, if unfavorable conditions prevail, first encyst. Similar embryonic stages bearing caudal and frontal cirri are produced both by direct development and by excystment of the encysted bud. Embryos develop rapidly into trophic forms which finally grow into small adults capable of asexual binary fission. During binary fission the nuclei behave as described previously for other members of the Oxytrichidae. A reorganization band forms at the outer end of each macronucleus, and these bands move along the macronuclei towards each other, finally disappearing at the inner ends. A fusion nucleus is then formed which splits into 4 pieces, 2 of which pass to the proter and 2 to the opisthe. During bud formation the reorganisation bands form and move as in binary fission. No fusion nucleus is formed, but the macronuclei divide immediately after reorganization, and the anterior macronucleus of each pair so produced migrates to the budding region. The infraciliature of H. vorax resembles that of Opisthotricha monspessulana.‘Erratic’ kinetosomes, which are present in the adult, divide during binary fission and so produce the infraciliature of the proter and opisthe. During bud formation the budding region receives a number of these ‘erratic’ kinetosomes from the mother cell, and these divide to form the infraciliature of the bud.

Resting Cysts in the Ciliate Class Polyhymenophorea: Phylogenetic Implications1

“…13), Gastrostyla (35, 36) ( Fig. 14), Histriculus (4), Keronopsis (25), Onvchodrornus ( 16), Oxytricha ( 1 1. 12) (Fig.…”

Characterization of a Novel Hypotrich Ciliate From Heavy Metal-Contaminated Industrial Outlet in Onsan, Ulsan, South Korea

“…H. vorax has been reported with rather variable shapes, i.e., about 170 µm (Stokes, 1891), small adult cells 70-140 × 50-60 µm, and large adult cells 190-250 × 100-120 µm (Curds, 1966). The body margin is often indented, with the left margin a Data based on mounted, protargol-impregnated, and randomly selected specimens from several clonal cultures fed with Chlorogonium elongatum (measurements in micrometer, µm).…”

“…For the remaining Histriculus species, no morphogenetic data are known. However, Curds (1965Curds ( , 1966 reported morphogenesis in H. vorax by the formation of an endogenous bud that also needs to be reinvestigated since Pang and Zhang (1981) assumed it to be the cannibalism induced by overfeeding. No endogenous bud formation was observed in H. tolerans.…”