Nucleomorphs are the remnant nuclei of algal endosymbionts that were engulfed by nonphotosynthetic host eukaryotes. These peculiar organelles are found in cryptomonad and chlorarachniophyte algae, where they evolved from red and green algal endosymbionts, respectively. Despite their independent origins, cryptomonad and chlorarachniophyte nucleomorph genomes are similar in size and structure: th...

A typical eukaryotic gene is comprised of alternating stretches of regions, exons and introns, retained in and spliced out a mature mRNA, respectively. Although the length of introns may vary substantially among organisms, a large fraction of genes contains short introns in many species. Notably, some Ciliates (Paramecium and Nyctotherus) possess only ultra-short introns, around 25 bp long. In ...

Considering increasing interest in calcium stores in protozoa, including parasitic forms, and specifically in subplasmalemmal stores in higher eukaryotes, we have isolated subplasmalemmal calcium stores (alveolar sacs) from the ciliated protozoan, Paramecium tetraurelia. Using antibodies against established sarco(endo)plasmic reticulum Caz+-ATPases (SERCAs) we detected in Western blots of subce...

Rab7 is a small GTPase that plays a crucial role in the regulation of transport from early to late endosomes and lysosomes, phagosome maturation and in lysosomal biogenesis in mammalian cells. It contains conserved and unique sequence elements that mediate its function. Two Rab7 genes, Rab7a (703 bp) and Rab7b (707 bp) were identified in the unicellular eukaryote Paramecium by PCR amplification...

The intergenic region between the hemoglobin (hb) and nucleosome assembly protein-1 (nap-1) genes in the Paramecium caudatum macronuclear genome was previously found to be heterogeneously composed. Cloning of this intergenic region from the macronuclear genomic DNA identified four unique DNA fragments of different sizes. Sequencing of the cloned fragments revealed extreme heterogeneity and char...

The green ciliate Paramecium bursaria contains several hundred symbiotic Chlorella species. We previously reported that symbiotic algal carbon fixation is enhanced by P. bursaria extracts and that the enhancing factor is a heat-stable, low-molecular-weight, water-soluble compound. To identify the factor, further experiments were carried out. The enhancing activity remained even when organic com...

Oxygen inhibition of photosynthesis and CO(2) evolution during photorespiration were compared in high CO(2)-grown and air-grown Chlorella pyrenoidosa, using the artificial leaf technique at pH 5.0. High CO(2) cells, in contrast to air-grown cells, exhibited a marked inhibition of photosynthesis by O(2), which appeared to be competitive and similar in magnitude to that in higher C(3) plants. Wit...

Paramecium trichocysts are unusual secretory organelles in that: (a) their crystalline contents are built up from a family of low molecular mass acidic proteins; (b) they have a precise, genetically determined shape; and (c) the crystalline trichocyst contents expand rapidly upon exocytosis to give a second, extracellular form which is also an ordered array. We report here the first step of our...

ARAMECIUM bursaria is one of the most widely distributed of P the species of Paramecium, though it does not as a rule occur in such large numbers in a given region as does sometimes Paramecium caudatum. It occurs commonly amid growing vegetation in the quiet parts of pools, ponds or streams. It does not flourish in regions in which the water is foul or there is much decaying vegetation. ’ The s...

SYNOPSIS. Methods are described for the recovery of highly purified DNA from Paramecium aurelia and Tetrahymena pyriformis in high yields. Our DNA is only slightly contaminated with RNA and carbohydrate, and little or no protein can be detected. We could not reduce the RNA (orcinol-positive material) by further treatment (sephadex or hydroxyapatite chromatography and preparative CsCl gradients)...