Biomedical subjects

Y Saimi

Publications and source records attributed to Y Saimi.

57 records · Page 4Linked to original sources

PubMedDate not supplied

A comparison of internal eliminated sequences in the genes that encode two K(+)-channel isoforms in Paramecium tetraurelia.

We examined both the somatic (macro-) and the germinal (micronuclear) DNAs that encode two K(+)-channel isoforms, PAK1 and PAK11, in Paramecium tetraurelia. The coding regions of these two isoforms are 88% identical in nucleotides and 95% identical in amino acids. Their introns are also highly conserved. Even some of the internal eliminated sequences in PAK1 and PAK11 are clearly related. PAK1 has five IESs; PAK11 has four. The first (5'-most) IESs of the two genes are located at the same site in the coding sequence but differ in size. The 2nd IES in PAK1 (206-bp), the largest among the nine IESs, has no PAK11 counterpart. The 3rd, 4th and 5th IESs in PAK1 have a counterpart in PAK11 that is similar in size and in sequence, and identical in its position in the coding sequence. In addition, the first IES of PAK11 bears some resemblance to the 4th one of PAK1. The similarities and differences between the two sets of IESs are discussed with respect to the origin and divergence of the two K(+)-channel isoforms.

Amino Acid Sequence↗

PubMedDate not supplied

Transformation of Paramecium tetraurelia by electroporation or particle bombardment.

Methods for mass transformation of Paramecium tetraurelia were established using plasmids bearing neomycin-resistance or calmodulin gene fragments. Phenotypic and molecular analyses showed that, although variable, up to 5% transformation can be achieved by electroporation. Concentrations of divalent cations Ca2+ and Mg2+ in the electroporation medium were crucial for efficient transformation. Strong neomycin-resistance transformation using bioballistic particle bombardment with gold particles was observed. For both methods, hybridization to transformant DNA revealed plasmid signals consistent with macronuclear transformation and correlated with transformed phenotypes. Complementation of a known calmodulin gene mutation was also achieved by mass transformation. Possible sources of variation and the general utility of these methods are discussed.

Animals↗

PubMedDate not supplied

Recent advances in the molecular genetics of Paramecium.

Paramecium continues to be used to study motility, behavior, exocytosis, and the relationship between the germ and the somatic nuclei. Recent progress in molecular genetics is described. Toward cloning genes that correspond to mutant phenotypes, a method combining complementation with microinjected DNA and library sorting has been used successfully in cloning several novel genes crucial in membrane excitation and in trichocyst discharge. Paramecium transformation en masse has now been shown by using electroporation or bioballistics. Gene silencing has also been discovered in Paramecium, recently. Some 200 Paramecium genes, full length or partial, have already been cloned largely by homology. Generalizing the use of gene silencing and related reverse-genetic techniques would allow us to correlate these genes with their function in vivo.

Animals↗