Extremely short 20–33 nucleotide introns are the standard length in<i>Paramecium tetraurelia</i>

Russell, Chris B.; Fraga, Dean; Hinrichsen, Robert D.

doi:10.1093/nar/22.7.1221

Cited by 74 publications

(54 citation statements)

References 33 publications

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“…of the translation initiation codon); in DHC-8, the intron begins at nucleotide 170. As in other Paramecium genes (Russell et al, 1994) the identified introns are short (23-28 nucleotides) and conform to the GT-AG rule for splicing (reviewed in Moore et al, 1993). It is possible that other introns, which do not alter the reading frames, are present in both genes.…”

Section: Resultsmentioning

confidence: 86%

The dynein genes of Paramecium tetraurelia: the structure and expression of the ciliary beta and cytoplasmic heavy chains.

Kandl

Forney

Asai

1995

MBoC

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The genes encoding two Paramecium dynein heavy chains, DHC-6 and DHC-8, have been cloned and sequenced. Sequence-specific antibodies demonstrate that DHC-6 encodes ciliary outer arm beta-chain and DHC-8 encodes a cytoplasmic dynein heavy chain. Therefore, this study is the first opportunity to compare the primary structures and expression of two heavy chains representing the two functional classes of dynein expressed in the same cell. Deciliation of paramecia results in the accumulation of mRNA from DHC-6, but not DHC-8. Nuclear run-on transcription experiments demonstrate that this increase in the steady state concentration of DHC-6 mRNA is a consequence of a rapid induction of transcription in response to deciliation. This is the first demonstration that dynein, like other axonemal components, is transcriptionally regulated during reciliation. Analyses of the sequences of the two Paramecium dyneins and the dynein heavy chains from other organisms indicate that the heavy chain can be divided into three regions: 1) the sequence of the central catalytic domain is conserved among all dyneins; 2) the tail domain sequence, consisting of the N-terminal 1200 residues, differentiates between axonemal and cytoplasmic dyneins; and 3) the N-terminal 200 residues are the most divergent and appear to classify the isoforms. The organization of the heavy chain predicts that the variable tail domain may be sufficient to target the dynein to the appropriate place in the cell.

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Section: Resultsmentioning

confidence: 86%

The dynein genes of Paramecium tetraurelia: the structure and expression of the ciliary beta and cytoplasmic heavy chains.

Kandl

Forney

Asai

1995

MBoC

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“…A comparison of the genomic sequence with their cDNA equivalent revealed six introns of 22 bp, 23 bp, 25 bp, 27 bp, 28 bp and 29 bp (Fig. 1A), a length typical for Paramecium (Russell et al, 1994;Sperling et al, 2002). The gene was named IP 3 R N (accession number CR932323).…”

Section: Resultsmentioning

confidence: 99%

An Ins(1,4,5)P3 receptor in Paramecium is associated with the osmoregulatory system

Ladenburger

Korn

Kasielke

et al. 2006

Journal of Cell Science

124

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In the ciliate Paramecium, a variety of well characterized processes are regulated by Ca2+, e.g. exocytosis, endocytosis and ciliary beat. Therefore, among protozoa, Paramecium is considered a model organism for Ca2+ signaling, although the molecular identity of the channels responsible for the Ca2+ signals remains largely unknown. We have cloned - for the first time in a protozoan - the full sequence of the gene encoding a putative inositol (1,4,5)-trisphosphate (Ins(1,4,5)P3) receptor from Paramecium tetraurelia cells showing molecular characteristics of higher eukaryotic cells. The homologously expressed Ins(1,4,5)P3-binding domain binds [3H]Ins(1,4,5)P3, whereas antibodies unexpectedly localize this protein to the osmoregulatory system. The level of Ins(1,4,5)P3-receptor expression was reduced, as shown on a transcriptional level and by immuno-staining, by decreasing the concentration of extracellular Ca2+ (Paramecium cells rapidly adjust their Ca2+ level to that in the outside medium). Fluorochromes reveal spontaneous fluctuations in cytosolic Ca2+ levels along the osmoregulatory system and these signals change upon activation of caged Ins(1,4,5)P3. Considering the ongoing expulsion of substantial amounts of Ca2+ by the osmoregulatory system, we propose here that Ins(1,4,5)P3 receptors serve a new function, i.e. a latent, graded reflux of Ca2+ to fine-tune [Ca2+] homeostasis.

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“…Other than in piroplasmids, such tiny introns have not been demonstrated in the CCTη gene from alveolates such as the apicomplexans Toxoplasma, Neospora, and Plasmodium and the ciliate Tetrahymena. Comparatively small (25 to 29 nt) introns reside in the CCTη gene of ciliate Paramecium (GenBank accession number NC_006058), and the tiny introns (~19 to 23 nt) have been reported in macronuclear genome of Paramecium [29] and nucleomorph genome of chlorarachniophytes [7]. Gilson et al surmised that the tiny introns in chlorarachniophytes may originate as miniaturizations of the larger introns present in the endosymbiont at the time of capture [7].…”

Section: Discussionmentioning

confidence: 99%

Babesia microti-Group Parasites Compared Phylogenetically by Complete Sequencing of the CCT.ETA. Gene in 36 Isolates

et al. 2009

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ABSTRACT. Babesia microti, the erythroparasitic cause of human babesiosis, has long been taken to be a single species because classification by parasite morphology and host spectrum blurred distinctions between the parasites. Phylogenetic analyses of the 18S ribosomal RNA gene (18S rDNA) and, more recently, the β-tubulin gene have suggested inter-group heterogeneity. Intra-group relationships, however, remain unknown. This study was conducted to clarify the intra-and inter-group phylogenetic features of the B. microti-group parasites with the η subunit of the chaperonin-containing t-complex polypeptide l (CCTη) gene as a candidate genetic marker for defining the B. microti group. We prepared complete sequences of the CCTη gene from 36 piroplasms and compared the phylogenetic trees. The B. microti-group parasites clustered in a monophyletic assemblage separate from the Babesia sensu stricto and Theileria genera and subdivided predominantly into 4 clades (U.S., Kobe, Hobetsu, Munich) with highly significant evolutionary distances between the clades. B. rodhaini branched at the base of the B. microti-group parasites. In addition, a unique intron presence/absence matrix not observable in 18S rDNA or β-tubulin set the B. microti group entirely apart from either Babesia sensu stricto or Theileria. These results have strong implications for public health, suggesting that the B. microti-group parasites are a full-fledged genus comprising, for now, four core species, i.e., U.S., Kobe, Hobetsu, and Munich species nova. Furthermore, the CCTη gene is an instructive and definitive genetic marker for analyzing B. microti and related parasites.

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Extremely short 20–33 nucleotide introns are the standard length inParamecium tetraurelia

Cited by 74 publications

References 33 publications

The dynein genes of Paramecium tetraurelia: the structure and expression of the ciliary beta and cytoplasmic heavy chains.

The dynein genes of Paramecium tetraurelia: the structure and expression of the ciliary beta and cytoplasmic heavy chains.

An Ins(1,4,5)P3 receptor in Paramecium is associated with the osmoregulatory system

Babesia microti-Group Parasites Compared Phylogenetically by Complete Sequencing of the CCT.ETA. Gene in 36 Isolates

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