bluuebunny/crossref_metadata_2025_split huggingface dataset:
Adoptive transfer of the hematopoietic system of trisomic mice with limited life span: Stem cells from six different trisomies are capable of survival
Authors: Herbst Eberhard W. , Winking Heinz 
Published: May 2005

AbstractThe life span of murine trisomies is limited to the fetal or early postnatal period. However, rescue of the hematopoietic system of fetal mice with trisomies (Ts) 12, 13, 14, 16, 18, and 19 is possible by transplanting hematopoietic stem cells from the liver into lethally irradiated adult hosts. Thus, radiation chimeras with permanent and almost complete trisomic hematopoietic and lymphocytopoietic systems were constructed. The longest documented survival of a trisomic graft was 12 months in Ts 19 chimeras. Blood counts in trisomic chimeras reveal a marked anemia in Ts 16 chimeras; lymphocytopenia in Ts 12, Ts 16, and Ts 19 chimeras; and granulocytopenia in Ts 18 chimeras. Survival rates of Ts 12, Ts 18, and Ts 19 chimeras were not different from those of the respective controls, whereas survival rates of chimeras with Ts 13 and Ts 16 hematopoiesis were markedly reduced and that of Ts 14 chimeras only slightly reduced. These results indicate that transplanted hematopoietic stem cells from Ts 13, Ts 14, and Ts 16 fetuses exhibit relevant genetically determined defects, resulting in a reduced restoration capacity of hematopoietic organs and/or deficiencies of differentiated blood cells. © 1992 Wiley‐Liss, Inc.
Pheromone 4 gene of Euplotes octocarinatus
Authors: Meyer Frank , Schmidt Helmut J. , Heckmann Klaus 
Published: May 2005

AbstractWe have cloned and sequenced a 1.7 kb macronuclear chromosome encoding the pheromone 4 gene of Euplotes octocarinatus. The sequence of the secreted pheromone is preceded by a 42 amino acid leader peptide, which ends with a lysine residue. The sequence coding for the leader peptide contains information for a putative signal peptide and is interrupted by a 772 bp intron as shown by comparison with a cDNA clone. A 64 bp intron and a 145 bp intron interrupt the sequence coding for the secreted pheromone. The three introns contain typical 5′ and 3′ splice junctions and a putative branch point site. The small introns have a low GC content. The large intron has a GC content similar to that of the pheromone 4 gene exons. The amino acid sequence of pheromone 4, deduced from both the genomic DNA and the cDNA of pheromone 4, shows that the secreted pheromone consists of 85 amino acids. One of its amino acids is encoded by a UGA codon. Since it has been shown for pheromone 3 of E. octocarinatus that UGA is translated as cysteine, it is assumed that the UGA codon encodes cysteine in pheromone 4 as well. The 164 bp noncoding region upstream of the leader peptide is AT‐rich and contains an inverted repeat capable of forming a stem‐loop structure with a stem of 11 bp. The 151 bp noncoding region at the 3′ end of the chromosome contains a putative polyadenylation sequence and an inverted repeat. The macro‐nuclear molecule is flanked by telomeres and carries the pentanucleotide motif TTGAA, located at a distance of 17 nucleotides from the telomeres. This motif has been suggested to be involved in the formation of macronuclear chromosomes. © 1992 Wiley‐Liss, Inc.
Ciliary polypeptides and glycoconjugates of wild‐type and mutant Tetrahymena thermophila: Starved versus nonstarved
Authors: Cheng Lee‐Ju , Hufnagel Linda A. 
Published: May 2005

AbstractTo investigate the role of cilia in mating interactions of Tetrahymena thermophila, ciliary membrane‐rich fractions were isolated from two wild‐type strains, a non‐discharge mucocyst mutant which possesses mating behavior similar to wild‐type, and a mating mutant which is able to costimulate cells of complementary mating type but cannot enter into pair formation. In each case, proteins from the ciliary membrane‐rich fractions of starved, mating‐competent (“initiated”) cells were compared with those from non‐starved, mating‐incompetent (“non‐initiated”) cells, by gel electro‐phoresis and lectin blotting. In stained gels, a 43 kDa polypeptide was reduced or absent in initiated cells but present in non‐initiated cells, in all strains. In silver‐stained gels, a 25 kDa polypeptide was present in all strains, both initiated and non‐initiated. In blots probed with Con A‐peroxidase, a 25 kDa glycoprotein was present in ciliary membrane fractions from non‐initiated cells and absent in membranes of initiated cells of the two wild‐type strains and the mucocyst mutant, but is present in initiated and non‐initiated cells of the mating mutant (several hypotheses are presented to explain these findings). In addition, ciliary proteins of the mating mutant included at least two unique Con A‐binding polypeptides. Our results support the idea that development of mating competence during starvation involves an extensive remodeling of ciliary membranes, and identify a 25 kDa glyco‐conjugate as having a potential role in control of pair formation during mating. © 1992 Wiley‐Liss, Inc.
Mapping the mating type locus of Tetrahymena thermophila: Meiotic linkage of mat to the ribosomal RNA gene
Authors: Bleyman Lea K. , Baum Mary P. , Bruns Peter J. , Orias Eduardo 
Published: May 2005

AbstractTetrahymena thermophila has a multiple mating type system. While a sexually mature cell usually expresses only one mating type, its germline (micronucleus) carries the genetic potential for 5 to 7 mating types. The set of allowed mating types is specified by the mat locus. The choice of which particular mating type is expressed by a cell reflects a somatically inherited, developmentally programmed differentiation of the somatic nucleus (macronucleus). In this work we report that the mat locus maps to the left arm of chromosome 2, as determined by nullisomic deletion mapping. We also report a distance of 29 cM between the mat locus and the ribosomal RNA gene, previously mapped to chromosome 2L. This represents another (rare) case of meiotic linkage in Tetrahymena. © 1992 Wiley‐Liss, Inc.
Development of sexual maturity in the ciliate Euplotes crassus: Sources of variation in the timing of maturity
Authors: Dini Fernando , Nyberg Dennis 
Published: May 2005

AbstractThe life styles of ciliated protists are particularly suitable for experimental analyses of certain aspects of developmental and genetic biology. The progression from sexual immaturity tomaturity to senescence represents one of the most intriguing aspects of developmental programs. The extent to which progeny clones, their subclones, and testers used in the assay result in different lengths of immaturity has been investigated in Euplotes crassus. Six subclones from each of 12 progeny clones from a cross between stocks EC1 and EC2 were tested for maturity with stocks EC3, EC4, and EC5 on every transfer. Analysis of variance was used to partition thetotal variation in fissions to maturity into parts due to clones, subclones, and testers and the interactions between these levels. The error, interaction of subclones and testers, corresponds to a standard deviation of only 4.1 fissions, while the within clone within tester means range from 15.2 to 46.7 fissions; all levels except testers contribute significantly to the total variation. Most of the variability is attributable to clones (66%), the next most to error (16%), the next most to interaction of clones by testers (13%), and the least to subclones (5%). An a posteriori analysis examined whether the differences among clones were due to the cytoplasm of the clone ancestor (exconjugant), its mat (mating‐type) locus genotype, or the mated pair it came from. None of these characteristics was able to interpret simply the large variability among clones. These results provide evidence that the transition from immaturity to maturity is quantitative and complex rather than a jump from one well‐defined state to another. © 1992 Wiley‐Liss, Inc.
Developmental expression of macronuclear specific antigen in Paramecium caudatum
Authors: Fujishima Masahiro , Inoue Yasutake , Sawada Tomoo , Fukumoto Tetsuo 
Published: May 2005

AbstractWe obtained a monoclonal antibody (MA‐1) specific for macronuclei of the ciliate Paramecium caudotum and P. dubosqui. Immunoblotting showed that the antigen was a poly‐peptide of 50 kilodalton (kDa). During the process of nuclear differentiation in P. caudatum, the MA‐1 antigens appeared in the macronuclear anlagen immediately after four out of eight post zygotic nuclei differentiated morphologically into the macro‐nuclear anlagen. Afterwards, the antigens could be detected in the macronucleus through the cell cycle, and disappeared when the macronucleus began to degenerate in exconjugant cells. These results suggest that the antigens may play a role in the differentiation and function of the macronucleus. © 1992 Wiley‐Liss, Inc.
Scrambled actin I gene in the micronucleus of Oxytricha nova
Authors: Prescott David M. , Greslin Arthur F. 
Published: May 2005

AbstractIn the hypotrichous ciliate Oxytricha nova the cloned precursor gene from the micronuclear genome that encodes actin I is composed of highly disordered blocks of deoxynucle‐otide sequences. We present and illustrate in detail a recombination model that explains how the actin I gene may be unscrambled during macronuclear development after cell mating. The model was described in a previous publication (Greslin et al.: Proc Natl Acad Sci USA 86:6264‐6268, 1989). Here we show the data, described in the earlier publication, that support the model. The data show that scrambling is not an artifact of cloning. They rule against the presence of an unscrambled copy of the actin I gene in the micronucleus, which means that unscrambling must be a part of macro‐nuclear development. Finally, the data prove that the actin I gene in O. trifallax is scrambled in a pattern that resembles the pattern in O. nova. © 1992 Wiley‐Liss, Inc.
Stable and unstable transformation by microinjection of macronucleoplasm in Paramecium
Authors: Harumoto Terue , Hiwatashi Koichi 
Published: May 2005

AbstractTransformation by microinjection of macronucleoplasm in Paramecium caudatum was investigated. Macronucleoplasm with three genetic markers (behavior, trichocyst, and mating type) was injected into the macronucleus. To facilitate microinjection, in most cases, paramecia were immobilized in a gelatin (7.5%) solution. The injected cells began to express a dominant gene (cnrA+ or cnrB+) of the donor 9–24 hr after injection. Expression did not require cell division suggesting injected macronucleoplasm was capable of expressing a phenotype. The amount of injected macronucleoplasm appears to correlate with the frequency of successful expression but not to correlate with the time required for expression. After a number of fissions, the injected cells produced clones which had cells expressing the phenotype of the donor. This suggests that injected macronucleoplasm was replicated and expressed in the recipient cell lines. The transformed clones were classified into two groups. In one group, transformation was stable. All cell lines derived from the injected cells expressed a phenotype similar to the heterozygote of donor and recipient cells. In the other group, transformation was unstable. During the first five to seven fissions after injection, at each division, cells produced one daughter cell which later reverted to the recipient phenotype. After this unstable period, cells no longer produced the recipient phenotype but produced the donor phenotype exclusively. Donor and recipient phenotypes were, thus, segregated in different cell lines. Observation of genetic markers and analysis by computer simulation shed light on the mode of transmission of injected macronucleoplasm. In stable transformation, injected macronucleoplasm appears to be distributed equally to daughter cells. In unstable transformation, injected macronucleoplasm is distributed only to one of the daughter cells at every division until about the fifth to seventh fission after injection and then begins to assort equally to daughter cells. The cell cycle stage at injection may influence the mode of transformation. Interspecific microinjection of macronucleoplasm from P. multimicronucleatum and P. tetraurelia to P. caudatum. resulted in the expression of foreign genes in P. caudatum. In one case, injection of macronucleoplasm of P. tetraurelia produced a stable transformant indicating replication of foreign macronucleoplasm in P. caudatum. This work reveals the mode of transformation by injected macronucleoplasm and shows the possibility of transformation among Paramecium species, which is significant in the study of the conservation of gene products and the mechanism of gene expression in different species. © 1992 Wiley‐Liss, Inc.
Inheritance of the group I rDNA intron in Tetrahymena pigmentosa
Authors: Nielsen Henrik , Simon Ellen M. , Engberg Jan 
Published: May 2005

AbstractWe have previously argued from phylogenetic sequence data that the group I intron in the rRNA genes of Tetrahymena was acquired by different Tetrahymena species at different times during evolution. We have now approached the question of intron mobility experimentally by crossing intron+ and intron− strains looking for a strong polarity in the inheritance of the intron (intron homing). Based on the genetic analysis we find that the intron in T. pigmentosa is inherited as a neutral character and that intron+ and intron− alleles segregate in a Mendelian fashion with no sign of intron homing. In an analysis of vegetatively growing cells containing intron+ and intron− rDNA, initially in the same macronucleus, we similarly find no evidence of intron homing.During the course of this work, we observed to our surprise that progeny clones from some crosses contained three types of rDNA. One possible explanation is that T. pigmentosa has two rdn loci in contrast to the single locus found in T. thermophila. Some of the progeny clones from the genetic analysis were expanded for several hundred generations, and allelic assortment of the rDNA was demonstrated by subcloning analysis. © 1992 Wiley‐Liss, Inc.
Immunocytochemical analysis of secretion mutants of Tetrahymena using a mucocyst‐specific monoclonal antibody
Authors: Turkewitz Aaron P. , Kelly Regis B. 
Published: May 2005

AbstractDense‐core granules represent an adaptation of specialized secretory cell to facilitate stimulus‐regulated release of stored proteins. Such granules are a prominent feature of mammalian neuroendocrine and exocrine cells and are also well developed in the ciliates. In Tet‐rahymena thermophila, the ability to generate mutants in dense‐core granule biosynthesis and fusion presents a versatile system for dissecting steps in regulated exocytosis. We have previously shown that defective granules in such mutants could be characterized by several biochemical criteria, including buoyant density, which increases during maturation, and the degree of proteolytic processing of the content precursors. We have now used indirect immunofluorescence, taking advantage of a monoclonal antibody directed against a granule protein, to visualize the morphology and distribution of both granules and putative granule intermediates in mutant and wild‐type cells. The results are consistent with the biochemical analysis and extend our characterization of the mutants, allowing us to distinguish four classes. In addition, the assay represents a powerful technique for diagnosis of new mutants. © 1992 Wiley‐Liss, Inc.
Genetic characterization of Tetrahymena thermophila mutants unable to secrete capsules
Authors: Gutierrez Juan Carlos , Orias Eduardo 
Published: May 2005

AbstractUnder appropriate conditions, Alcian Blue‐induced exocytosis of Tetrahymena mucocysts leads to formation of a capsule that surrounds the cell. This phenomenon is an example of regulated secretion, a mechanism of fundamental significance in eukaryotic cells. In order to dissect genetically the mechanism of mucocyst biogenesis and regulated exocytosis, mutants unable to form capsules (Caps–) were isolated. In this paper we report a genetic characterization of Caps– mutants in this collection. The mutations in mutants SB255 and SB281 behave as single recessive Men‐delian mutations. The mutation in SB251 is restricted to the macronucleus, and could not be further characterized by the genetic methods we used. Complementation tests suggest the existence of at least 2 genes, named exoA and exoB; additional mutant loci are likely to be included in the mutant collection. Deletion mapping using nulli‐somic strains showed that exoA and exoB are located on the left arm of chromosome 4. The exo‐3 mutation, which behaves as recessive and complements with exoA1 in SB255 and exoB2 in SB281, maps to chromosome 3. These Caps– mutants may be useful for the elucidation of the developmental pathway of mucocyst biogenesis and the control of regulated secretion in eukaryotic cells. © 1992 Wiley‐Liss, Inc.
Locus‐dependent profiles of the rescue of nonexcitable behavioral mutants during conjugation in Tetrahymena thermophila
Authors: Takahashi Mihoko 
Published: May 2005

AbstractThe Tetrahymena nonreversal (TNR) mutants of Tetrahymena thermophila are behavioral mutants with nonexcitable membranes. When cells of the tnrB mutant were mated with wild type, a phenotypic change occurred about l h after pair formation. The pairs began to lose their heterotypic character in stimulation solution containing high potassium and, within 1 1/2h, they were not distinguishable from the wild‐type homotypic pairs. On the contrary, although pairs of the tnrA and wild type also lost their heterotypic character about 1 1/2 h after pair formation, they never showed a full response as wild‐type homotypic pairs. When tnrA was mated with tnrB more than 50% of pairs expressed a heterotypic pair character 2 h after pair formation, consistent with the tnrB defect having been rescued but not the tnrA defect. Thus, conjugation rescue of the mutant phenotype is locus dependent and probably reflects the nature of the gene products controlling voltage‐dependent Ca2+ channels. © 1992 Wiley‐Liss, Inc.
Genes and structural patterns in ciliates: Vance tartar and the “cellular architects”
Authors: Frankel Joseph 
Published: May 2005

AbstractThe one form of cytoplasmic inheritance that has not been assimilated into the Central Dogma is the inheritance of surface structural patterns, a phenomenon most clearly expressed in cilates. Vance Tartar, although he worked with a genetically undomesticated organism (Stentor coeruleus), provided early evidence for the crucial role of clonally propagated features of the cell cortex. He showed that the capacity for development of cortical organelle systems is associated with a particular relational feature, the “locus of stripe contrast” (LSC), and that clonally inherited cortical variants (homopolar doublets) could be created at will by microsurgical operations that duplicated the LSC. Tartar also hoped to demonstrate the existence of what David Nanney called “cellular architects” by provoking stentors to carry out entirely novel types of morphogenetic performances. He eventually acknowledged failure, although the bizarre juxtapositions by which he attempted to elicit such novel performances did bring about specific and illuminating defects in cortical development. Subsequent analyses of similar defects in other ciliates revealed not the unitary “pattern factor” postulated by Tartar, but rather a hierarchy of distinct patterning mechanisms. Nonetheless, by pursuing an embryological approach toward morphogenesis in a highly regulative ciliate, Tartar uncovered relational aspects of pattern‐determination; this, in my view, delineates the major problem that we must solve to gain understanding of intracellular patterning. © 1992 Wiley‐Liss, Inc.
Structural deficiency of 180°‐rotated ciliary rows in Tetrahymena: Implications on the inheritance and development of a non‐genically acquired cortical trait during vegetative propagation
Authors: Lau Kin Mang , Ng Stephen F. 
Published: May 2005

AbstractThe present study reveals a deficiency in the number of ciliated basal bodies along 180° rotated ciliary rows (IRs) in Tetrahymena. This feature is common to IRs recently generated in young clones with stable corticotypes (total number of ciliary rows per cell), irrespective of the number of IRs present per cell or their cellular location, and is found before the cell loses any of the IRs. In cells bearing three IRs, the IRs on the two sides of the inversion immediately next to normal ciliary rows (junctures) exhibit an even greater deficiency in ciliated basal bodies, compared to the IR located internally between two other IRs; the normal ciliary rows flanking the inversion are also somewhat deficient. These observations show that the IRs of Tetrahymena are structurally deficient, hence developmentally defective, and suggest that they are intrinsically unstable. We propose that basal body development along IRs tends to be truncated before the stage of ciliation; such basal bodies would fail to acquire the potential to serve as nucleating centers for new basal body development in the next round of basal body proliferation, leading to the eventual loss of the IRs. © 1992 Wiley‐Liss, Inc.
Lithium‐Induced respecification of pattern in Paramecium
Authors: Beisson Janine , Ruiz Françoise 
Published: May 2005

AbstractThe long‐known teratogenic effects (dorsalisation) of lithium on amphibian embryos has recently raised renewed interest. As it is known that lithium blocks the polyphosphoinositide (PI) cycle, causing a depressed level of myo‐inositol, and as injections of myo‐inostiol have been shown to rescue the effects of Li+, it was postulated that Li+ causes a flattening of gradients of PI cycle activity underlying the developmental polarities. We have studied the effect of Li+ on the morphogenesis of the unicellular organism, Paramecium. We show (1) that exposure to 25 mM Li+ during division yields precise distorsions of the cortical pattern that can be explained by a uniformisation of surface growth i.e. partial suppression of the right/left and antero/posterior asymmetries and (2) that Li+ effects are rescued by injection of myo‐ inositol. These results suggest that spatially graded activity of the PI cycle (ensuring in turn a spatially graded distribution of secondary messengers directly involved in the morphogenetic processes) appeared early in evolution. © 1992 Wiley‐Liss, Inc.