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At least 649 records · Page 36Linked to original sources
PubMed1979

Bacteria-like structures in the endoplasm of Gregarina garnhami (Eugregarinida, Protozoa).

An investigation of bacteria-like structures, which are found in large numbers in the endoplasm of the eurgregarine, Gregarina garnhami, was carried out using light and electron microscopy. Gram staining indicates that these structures are gram negative; they show orange fluorescence when stained with acridine orange. Ultrastructural observations show that they resemble the endosymbiotic bacteria found in other protozoan species. Some of these structures appear to be dividing, and the possibility that these structures are in fact bacteria is discussed.

Bacteria↗
PubMed1980

Arrangement of coding and non-coding sequences in the DNA molecules coding for rRNAs in Oxytricha sp. DNA of ciliated protozoa. VII.

All of the genes in the macronucleus of Oxytricha sp. occur on physically separate "gene-sized" DNA molecules. We have inserted the DNA molecule that codes for rRNA into a bacterial plasmid in order to study its structure and function. Using restriction nuclease mapping and hybridization of 125I-rRNAs to gel separated DNA fragments we have determined that the intact rDNA is 8,140+/-50 base pairs (bp) in length. Reading from one end, the molecule consists of approximately 1,540 bp of non-coding DNA, approximately 2,100+/-50 bp that code for 19S rRNA, approximately 3,700+/-50 bp that code for 25 rTNA, and approximately 620+/-50 bp of non-coding DNDA. The 5.8S rRNA coding sequence (approximately 150 bp) occurs at one end of the 25S RNA coding region but which end is not known yet. All three rRNAs are encoded in the same strand of the DNA molecule, and transcription is in the order: 19S leads to 25S.

Animals↗
PubMed1980

Gene-sized DNA molecules of the macronuclei in three species of hypotrichs: size distributions and absence of nicks. DNA of ciliated protozoa. VIII.

Macronuclear DNA s from three related hypotrichous ciliated protozoans were compared by agarose gel electrophoresis. Each was shown to be composed of DNA duplexes that yielded a unique pattern of bands overlying a continuous distribution of DNA sizes ranging from approximately 400 bp to approximately 20,000 bp. By EM, the number average molecular sizes for double-stranded DNA were 2,200 bp for Oxytricha sp., 2,514 bp for Stylonychia pustulata and 18,836 bp for Euplotes aediculatus. Contrary to previous reports we present evidence that the macronuclear DNA s in each of these three organisms lack single-stranded interruptions.

Animals↗
PubMed1975

[The presence of lytic bacteria within cysts of Sarcocystis tenella (Sporozoa, Protozoa) (author's transl)].

In cysts of Sarcocystis tenella parasitic in the oesophage of sheep, bacteria of the Gram-negative type were found to lyse the limiting membranes of the banana-shaped parasites. In cysts of S. tenella the parasites are enclosed within chamber-like hollows of the ground substance. In old cysts, however, only the peripheral hollows are filled with parasites, whereas those of the midzonal region are empty. There is no explanation for this observation reported by several authors. In the present study we found large numbers of small bacteria (2-2.7 by 0.6 -0.8 mum) of the Gram-negative type within the center of the cyst. From this side they were seen to lyse the pellicle of the banana-shaped merozoites. There is no explanation how these bacteria might have penetrated through the muscle tissue into the interior of the cysts, for the parasites at the periphery, the cyst wall and the surrounding host cell were intact. The penetration of the bacteria during preparation can be excluded, too, because the cysts were fixed only seconds after the death of the animals. It might be possible that the bacteria had been present since the beginning of cyst formation.

Animals↗