John O. Corliss

Silver impregnation of ciliated protozoa by the Chatton-Lwoff technic.

The ciliates are manipulated at all stages by means of micropipettes and fine needles, proceeding by the following steps: Fix the material in a small receptacle with Champys fluid 1–3 minutes following with Da Fanos solution for several hours. Transfer the specimens to a slide, withdraw excess fluid and embed them in warm (35°–45°C.) gelatin containing 0.05% sodium chloride. Refrigerate in a moist chamber until the gelatin has set, and then immerse 10–20 minutes in 3% silver nitrate (aqueous) at 5–10°C. Wash with cold distilled water, submerge the preparation in cold water to a depth of several centimeters and expose to a strong light for 10–30 minutes. Silver is deposited on various pellicular structures which then appear black in the dehydrated and mounted specimens. Neatly revealed are the many longitudinal and transverse fibrils of the “silverline system”, basal granules of the cilia, bases of buccal ciliary organelles, contractile vacuole pores and the cytoproct. None of these structures, which tod...

Research in protozoology

Research in protozoology , Research in protozoology , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Tetrahymena chironomi sp.nov., a ciliate from midge larvae, and the current status of facultative parasitism in the genus Tetrahymena

A holotrichous ciliate found repeatedly in very large numbers in the body cavity of larval midges (Chironomus plumosus) from Paris and Berlin areas is described as a new species of the genus Tetrahymena , named T. chironomi sp.nov. It appears to represent a true example of facultative parasitism, since parasites released from the host survive in laboratory cultures, and free-living ciliates believed identical have been isolated from fresh-water sources in nature. Over a 3-month period more than 2000 larvae, principally fourth-instar stages, were examined; about 9 % of these were found to be infected with ciliates. T. chironomi is the thirteenth species to be added to the growing holotrich hymenostome genus Tetrahymena. It is taxonomically distinguishable from other members of the genus on the basis of a combination of characteristics related to its morphology and bionomics. It is one of the smallest species, has 24–27 ciliary meridians and a relatively large, spherical micronucleus, does not exhibit dimorphism or cystic stages in its life cycle, and does not possess a caudal cilium.

Stephanopogon, a Phylogenetically Important "Ciliate," Shown by Ultrastructural Studies to Be a Flagellate

A benthic marine protist (Stephanopogon) with a homokaryotic nucleus has long been considered to be a gymnostome ciliate. It has been important in hypotheses concerning the origin of ciliates, the evolution and origin of the dual nuclear apparatus of contemporary species of the Ciliophora, and the origin of the multicellular Eumetazoa. Ultrastructural observations reveal that the organism should be reclassified as a flagellate, despite its superficial resemblance to ciliates.

Protistan Phylogeny and Eukaryogenesis

Publisher Summary This chapter focuses on the nature of the protists themselves, a group deserving much attention today if for no other reason then for their suitability as model cells in experimental researches of diverse kinds and discusses approaches to a better understanding of their phylogenetic interrelationships. The three principal ways of treating the protists systematically/evolutionarily are illustrated diagrammatically. While recognition of the prokaryote–eukaryote division made possible the whole idea of (and even the word, of course) eukaryogenesis, it did not directly help focus taxonomic attention on the protists. Protista are eukaryotic organisms with no more than one true tissue at most. The majority are unicellular in organization and microscopic in size. Even in macroscopic multicellular species (e.g., brown algae), clearly differentiated tissue stages may be considered absent, and no vascular forms exist. Motile species (via flagella, cilia, or pseudopodia) are common and widespread among most groups.

Corpuscles : atlas of red blood cell shapes

On the Beauty of the Red Cell.- On the Beauty of the Red Cell.- On Nomenclature.- On Nomenclature.- The Normal Red Cell.- I Red Cell Birth.- II Discocytes.- Experimental Manipulations.- III Echinocytes.- IV Stomatocytes.- Pathological Shapes.- V Drepanocytes.- VI Echino-Drepanocytes and Stomato-Drepanocytes.- VII Keratocytes and Schizocytes.- VIII Dacryocytes.- IX Codocytes and Target Cells.- X Spherocytes and Knizocytes.- XI Elliptocytes.- XII Acanthocytes.- Interlude.- XIII Zoo.- Senescence and Death.- XIV Micro-spherulation.- XV Hemolysis.- XVI Red Cell Death.- Technique.

Why the World Needs Protists!1

Abstract In this brief review, literature references are given to researches—involving diverse species of protists—that support the authors firm conviction that the biological world of today absolutely requires the presence of numerous of these generally small and unicelled organisms if it is to survive. Examples supplied come from areas within the field of protistology sensu lato as widely separated as basic phycological research on photosynthesis and protozoological/medical/biomedical investigations on malaria and other pathogens of human beings. Emphasis is primarily on the most relevant works of the past 10–15 years, although historically highly significant papers of older vintage require at least indirect—and occasionally direct—citation.

Behaviour of Micro-organisms

The direction of swimming (forward or backward) in the ciliated protozoa depends on the orientation of the polarized cycle of ciliary movement. This orientation is coupled to membrane potential by membrane-limited movements of Ca2+ into the cell cortex and cilia. Stimuli which depolarize the cell cause the conductance of the membrane to Ca2+ to rise. As a consequence Ca2+, driven by its electrochemical gradient, shows a net influx and accumulates in the cilia and cell cortex. The increasing Ca2+ concentration activates the mechanism for ciliary reversal. As depolarization subsides and Ca2+ diffuses away from the cortex and/or is actively transported out of the cell, the cilia resume their forward-swimming orientation.

Protistan diversity and origins of multicellular/multitissued organisms∗

Abstract Some background information is first presented concerning the historically and evolutionarily significant prokaryote‐eukaryote split of the biotic world, widely accepted some 25 years ago, and the (re)emergence of the field of neoHaeckelian protistology in still more recent times. Two questions are then posed: how did eukar‐yogenesis come about, and what protistan groups may have served as progenitors of the plant, fungal, and animal kingdoms? Before either of these complex inquiries can be discussed properly, some data need to be given concerning the protists themselves, and progress made to date in research on these evolutionarily important forms of life requires brief review. The Protista are here tentatively considered to be a kingdom of ≪lower≫ eukaryotes embracing the algae, protozoa, and certain ≪lower≫ fungi. They are distinguished first of all by the fact that, while eukaryotic, they possess no more than one tissue. Most of the included 200 000 species (estimated) are unicellular in basi...

Advances in studies on phylogeny and evolution of protists

J. O. Corliss explained that the original title given to the Workshop (namely, the phylogeny and evolution of the protozoa) seemed out of date, since today we clearly cannot persist in separating various protozoa from many of the algae and from certain zoosporic fungi by erection of formidable taxonomic barriers at the phylum (division) or kingdom level. All such forms, the species of which are being discovered to be inextricably comingled at various levels (for the latest extensive review, see Corliss, 1984), are perhaps better assigned to a single kingdom Protista or to several kingdoms predominantly containing these ‘lower’ eukaryotes (see subsequent sections of this report, below).