The protozoa occurring in the hind-gut of cockroaches

Abstract

The size and shape of the trophozoite of Nyctotherus ovalis in different species of cockroaches was found to vary considerably, and this was attributed chiefly to the presence or absence of large paraglycogen granules within the ciliate.The size and shape of the cysts of N. ovalis which were passed in the faeces of the host on successive days were found to fluctuate around means which were more or less constant over a long period. The constants varied according to the species of the host: the largest and fattest cysts were found in the faeces from Blatta, the smallest and most slender from Blattella. Those from Blaberus were of the Blattella-type, but Periplaneta harboured populations which gave rise either to the Blatta-type of cysts or to the Blattella-type.The constant size and shape of the cysts was not altered when the host moulted, but there was always a decrease in size and sometimes a change of shape when an infection was established in a new host. The cause of these changes is unknown. An increase in size was induced by an increase in environmental temperature, but the size declined during a subsequent period at lower temperatures. The work of other authors on changes in the sizes of protozoan cysts is discussed.The cyst wall of N. ovalis consists of four separate layers plus an outer membrane. They all seemed to be proteinaceous in nature. Treatment with various inorganic reagents and proteolytic enzymes revealed that the knob is the most easily destroyed part of the wall. A histochemical test for keratin showed that this is the chief constituent of the wall. The keratin appeared to be least organized in the knob, and hence the knob is the least impermeable part of the wall.This work was done during the tenure of a Research Studentship awarded by the Agricultural Research Council. I am deeply indebted to Dr P. Tate for his encouragement and counsel at all stages of the work.

Some Aspects of the Physiology of the Nyctotherus velox, a Commensal Ciliated Protozoon Taken from the Hindgut of the Tropical Millipede Archispirostreptus gigas

“…In contrast, trophozoites from hindgut samples had far fewer granules and were more plum-shaped. The occurrence of intracellular storage polysaccharide particles was repeatedly observed in many Nyctotherus species [1,8,[54][55][56]. In older literature, the name paraglycogen was used.…”

Origin of Mutualism Between Termites and Flagellated Gut Protists: Transition From Horizontal to Vertical Transmission

“…The evolution of transmission mode of hindgut flagellates in the termite ancestor was closely associated with changes in host social structure and feeding behaviors (Nalepa et al, 2001). Horizontal transmission of microbes is typified by extant gregarious cockroaches, where hatchlings are inoculated primarily via coprophagy, the ingestion of feces produced by conspecifics which contain protozoan cysts, bacterial cells and spores (Hoyte, 1961b;Cruden and Markovetz, 1984;Hackstein and Stumm, 1994). Vertical transmission is exemplified by Cryptocercus, a subsocial cockroach whose neonates obtain their gut symbionts by feeding directly on the gut fluids of parents (proctodeal trophallaxis) (Seelinger and Seelinger, 1983;Nalepa, 1984;Park et al, 2002).…”

True molecular phylogenetic position of the cockroach gut commensal Lophomonas blattarum (Lophomonadida, Parabasalia)

“…Its abundance within the gut is influenced by the diet of its host: on a high‐protein diet, L. blattarum will die after a few weeks, but on a high‐carbohydrate diet, its numbers increase (Armer, 1944). It has a very low tolerance for oxygen, even relative to the ciliates and amoebae that coinhabit the anoxic to microoxic habitats of the cockroach gut (Cleveland, 1925; Hoyte, 1961).…”

“…Its abundance within the gut is influenced by the diet of its host: on a high-protein diet, L. blattarum will die after a few weeks, but on a highcarbohydrate diet, its numbers increase (Armer, 1944). It has a very low tolerance for oxygen, even relative to the ciliates and amoebae that coinhabit the anoxic to microoxic habitats of the cockroach gut (Cleveland, 1925;Hoyte, 1961).Lophomonas blattarum cells are spherical to pyriform in shape, measure 15-30 μm in length, and bear a characteristic tuft of ~50 flagella (Figure 1A,B;Kudo, 1926a). These flagella are inserted along a horseshoe shape on the cell apex that is subtended by a microtubular cuplike structure (calyx or chalice) that holds the nucleus at the anterior end of the cell.…”