Timing of the appearance of ubiquitinated histones in developing new macronuclei of Tetrahymena thermophila

1991 ◽  
Vol 69 (1) ◽  
pp. 66-71 ◽  
Author(s):  
James R. Davie ◽  
Rueyling Lin ◽  
C. David Allis
Keyword(s):  
Life Cycle ◽  
Western Blotting ◽  
Vegetative Growth ◽  
Tetrahymena Thermophila ◽  
Ciliated Protozoan ◽  
Active Chromatin ◽  
Somatic Nucleus ◽  
Vegetative Cells ◽  
Low Levels

Vegetative cells of the ciliated protozoan Tetrahymena thermophila contain a transcriptionally active macronucleus and a transcriptionally inert micronucleus. During vegetative growth, macronuclear histones H2A and H2B and micronuclear H2A are ubiquitinated. Despite differences in function, macro- and micro-nuclei are related. During conjugation (the sexual phase of the life cycle in Tetrahymena), postzygotic division products of micronuclei give rise to new micro- and macro-nuclei. Using an anti-ubiquitin antibody in Western blotting experiments, we determined the levels of ubiquitinated histones in new macro- and micro-nuclei at various times during conjugation. Very soon after the second postzygotic division (approximately 8 h) when new macronuclei begin to synthesize RNA, ubiquitinated H2B and polyubiquitinated H2A are present. At this time micronuclei have only low levels of ubiquitinated H2A. During later stages of conjugation (15 h), the level of polyubiquitinated H2A decreases, while ubiquitinated H2B increases in developing new macronuclei, attaining levels of ubiquitinated H2B approaching that of parental macronuclei. Ubiquitinated histones are not detectable in the 15-h micronuclei. These results show that ubiquitination of H2B coincides with the transformation of an inert germinal nucleus into that of a transcriptionally active somatic nucleus, suggesting that ubiquitinated H2B has a role in maintaining the transcriptionally active chromatin state.Key words: histone ubiquitination, Tetrahymena thermophila, chromatin, transcription.

The life history and ecology of the snow alga Chloromonas polyptera comb. nov. (Chlorophyta, Volvocales)

1983 ◽  
Vol 61 (9) ◽  
pp. 2416-2429 ◽  
Author(s):  
Ronald W. Hoham ◽  
John E. Mullet ◽  
Stephen C. Roemer
Keyword(s):  
Life Cycle ◽  
Developmental Stages ◽  
Laboratory Observation ◽  
Vegetative Cells ◽  
Snow Algae ◽  
Algal Succession ◽  
Snow Alga ◽  
Low Levels ◽  
Increasing Temperature ◽  
First Time

Snow algae previously designated as Carteria nivale, Scotiella polyptera, S. polyptera var. polimantii, and S. polyptera var. magellanica were found to be developmental stages of the zygote of Chloromonas polyptera comb. nov. Five species of Scotiella from snow have now been identified as zygotes of different specis of Chloromonas. In this life cycle, biflagellate vegetative cells, zoospores, gametes, and sexual reproduction are reported for the first time. The different forms of the zygote have been reported previously in the literature from several parts of the world, but have been misinterpreted as several distinct taxa of snow algae. The stages in the life cycle of Chloromonas polyptera occur in old, rapidly melting snowbanks, usually less than 30 cm deep. In the same snowbanks, zygotes of C. polyptera germinate later than those reported for Chloromonas nivalis, Chloromonas brevispina, and Chloromonas pichinchae indicating the occurrence of algal succession. Higher light intensity and a more saturated snowbank appear necessary for germination of zygotes of C. polyptera when compared with other species of Chloromonas found in snow. Low levels of carbon dioxide in snow may be limiting for growth of C. polyptera and vegetative cells are sensitive to increasing temperature as observed through laboratory observation. Freezing does not appear to initiate meiosis in the zygotes of C. polyptera as reported for other Volvocalean algae found in snow.

scholarly journals Timing of the appearance of macronuclear-specific histone variant hv1 and gene expression in developing new macronuclei of Tetrahymena thermophila.

1984 ◽  
Vol 98 (6) ◽  
pp. 2107-2117 ◽  
Author(s):  
D Wenkert ◽  
C D Allis
Keyword(s):  
Rna Synthesis ◽  
Tetrahymena Thermophila ◽  
Histone Variant ◽  
Mating Types ◽  
Ciliated Protozoan ◽  
Somatic Nucleus ◽  
Mammalian Cell Lines ◽  
And Function ◽  
Transcribed Sequences ◽  
In Cells

Vegetative cells of the ciliated protozoan Tetrahymena thermophila contain a transcriptionally active macronucleus and a transcriptionally inactive micronucleus. Earlier studies ( Allis , C. D., C. V. C. Glover , J. K. Bowen, and M. A. Gorovsky , 1980, Cell, 20:609-617; and Allis , C. D., Y. S. Ziegler , M. A. Gorovsky , and J. B. Olmsted, 1982, Cell, 31:131-136) demonstrated the existence of a macronuclear-specific histone variant, hv1 , which is enriched in small punctate regions in nucleoli of several mammalian cell lines. These observations suggest that this histone variant is highly conserved in evolution and may be associated with actively transcribed sequences. Despite large differences in structure and function during vegetative growth, macro- and micronuclei are related. During conjugation, the sexual phase of the life cycle in Tetrahymena, postzygotic division products of micronuclei give rise to new micro- and macronuclei, while the old macronucleus moves to the posterior of each cell and is eliminated. In this study using antiserum specific for hv1 , we determined by indirect immunofluorescence the time during conjugation at which hv1 first appears in the developing new macronuclei. In growing, starved, and young mating cells (2-5 h after mixing opposite mating types), only macronuclei are detected with affinity-purified antibodies against hv1 . Newly formed macronuclei are either not stained or only weakly stained in cells in which the old macronucleus is located in the center of the cell. However, new macronuclei are clearly observed in cells in which the old macronucleus has moved to the posterior of the cell (approximately 8 h). During later stages of conjugation (10-16 h), the intensity of hv1 staining in new macronuclei increases with time corresponding to the increasing DNA content of these nuclei. Disappearance of detectable hv1 from old macronuclei begins nearly 1 h after these nuclei reach the posterior cytoplasm (approximately 9-10 h) and is sometimes complete before these nuclei are eliminated from the cells. Autoradiography of cells labeled for brief periods with [3H]uridine shows that new macronuclei begin to synthesize RNA very soon after the second postzygotic division (approximately 8 h). During stages when hv1 is clearly detected in new macronuclei, anlagen are active in RNA synthesis. RNA synthesis in old macronuclei ceases very close to the time when RNA synthesis begins in new macronuclei. Thus, the addition of hv1 coincides closely with the transformation of a transcriptionally inactive germinal nucleus into that of a transcriptionally active somatic nucleus. We suspect that addition of hv1 plays a fundamental role in

scholarly journals Malaria parasites both repress host CXCL10 and use it as a cue for growth acceleration

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yifat Ofir-Birin ◽  
Hila Ben Ami Pilo ◽  
Abel Cruz Camacho ◽  
Ariel Rudik ◽  
Anna Rivkin ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Life Cycle ◽  
Cerebral Malaria ◽  
Survival Strategy ◽  
Parasitic Disease ◽  
Malaria Parasites ◽  
Sensing System ◽  
Rich Domain ◽  
Cargo Delivery ◽  
Low Levels

AbstractPathogens are thought to use host molecular cues to control when to initiate life-cycle transitions, but these signals are mostly unknown, particularly for the parasitic disease malaria caused by Plasmodium falciparum. The chemokine CXCL10 is present at high levels in fatal cases of cerebral malaria patients, but is reduced in patients who survive and do not have complications. Here we show a Pf ‘decision-sensing-system’ controlled by CXCL10 concentration. High CXCL10 expression prompts P. falciparum to initiate a survival strategy via growth acceleration. Remarkably, P. falciparum inhibits CXCL10 synthesis in monocytes by disrupting the association of host ribosomes with CXCL10 transcripts. The underlying inhibition cascade involves RNA cargo delivery into monocytes that triggers RIG-I, which leads to HUR1 binding to an AU-rich domain of the CXCL10 3’UTR. These data indicate that when the parasite can no longer keep CXCL10 at low levels, it can exploit the chemokine as a cue to shift tactics and escape.

scholarly journals Constitutive expression, not a particular primary sequence, is the important feature of the H3 replacement variant hv2 in Tetrahymena thermophila.

1997 ◽  
Vol 17 (11) ◽  
pp. 6303-6310 ◽  
Author(s):  
L Yu ◽  
M A Gorovsky
Keyword(s):  
Protein Sequence ◽  
Tetrahymena Thermophila ◽  
Histone H3 ◽  
Constitutive Expression ◽  
Histone Variants ◽  
Wild Type ◽  
Ciliated Protozoan ◽  
Knockout Mutant ◽  
Double Knockout ◽  
Constitutive Synthesis

Although quantitatively minor replication-independent (replacement) histone variants have been found in a wide variety of organisms, their functions remain unknown. Like the H3.3 replacement variants of vertebrates, hv2, an H3 variant in the ciliated protozoan Tetrahymena thermophila, is synthesized and deposited in nuclei of nongrowing cells. Although hv2 is clearly an H3.3-like replacement variant by its expression, sequence analysis indicates that it evolved independently of the H3.3 variants of multicellular eukaryotes. This suggested that it is the constitutive synthesis, not the particular protein sequence, of these variants that is important in the function of H3 replacement variants. Here, we demonstrate that the gene (HHT3) encoding hv2 or either gene (HHT1 or HHT2) encoding the abundant major H3 can be completely knocked out in Tetrahymena. Surprisingly, when cells lacking hv2 are starved, a major histone H3 mRNA transcribed by the HHT2 gene, which is synthesized little, if at all, in wild-type nongrowing cells, is easily detectable. Both HHT2 and HHT3 knockout strains show no obvious defect during vegetative growth. In addition, a mutant with the double knockout of HHT1 and HHT3 is viable while the HHT2 HHT3 double-knockout mutant is not. These results argue strongly that cells require a constitutively expressed H3 gene but that the particular sequence being expressed is not critical.

Structure and expression of two temperature-specific surface proteins in the ciliated protozoan Tetrahymena thermophila

1986 ◽  
Vol 6 (9) ◽  
pp. 3240-3245
Author(s):  
G A Bannon ◽  
R Perkins-Dameron ◽  
A Allen-Nash
Keyword(s):  
Cell Surface ◽  
Specific Surface ◽  
Incubation Temperature ◽  
Tetrahymena Thermophila ◽  
Sodium Dodecyl ◽  
Surface Protein ◽  
Surface Proteins ◽  
Ciliated Protozoan ◽  
Temperature Dependent ◽  
Molecular Sizes

The presence of specific proteins (known as immobilization antigens) on the surface of the ciliated protozoan Tetrahymena thermophila is under environmental regulation. There are five different classes (serotypes) of surface proteins which appear on the cell surface when T. thermophila is cultured under different conditions of temperature or incubation medium; three of these are temperature dependent. The appearance of these proteins on the cell surface is mutually exclusive. We used polyclonal antibodies raised against 30 degrees C (designated SerH3)- and 40 degrees C (designated SerT)-specific surface antigens to study their structure and expression. We showed that these surface proteins contain at least one disulfide bridge. On sodium dodecyl sulfate-denaturing polyacrylamide gels, the nonreduced 30 degrees C- and 40 degrees C-specific surface proteins migrated with molecular sizes of 69 and 36 kilodaltons, respectively. The reduced forms of the proteins migrated with molecular sizes of 58 and 30 kilodaltons, respectively. The synthesis of the surface proteins responded rapidly and with a time course similar to that of the incubation temperature. The synthesis of each surface protein was greatly reduced within 1 h and undetectable by 2 h after a shift to the temperature at which the protein is not expressed. Surface protein synthesis resumed by the end of 1 h after a shift to the temperature at which the protein is expressed. The temperature-dependent induction of these surface proteins appears to be dependent on the synthesis of new mRNA, as indicated by a sensitivity to actinomycin D. Surface protein syntheses were mutually exclusive except at a transition temperature. At 35 degrees C both surface proteins were synthesized by a cell population. These data support the potential of this system as a model for the study of the effects of environmental factors on the genetic regulation of cell surface proteins.

Effects of the Timing of the Life-Cycle on the Vegetative Growth of Some Dune Annuals

1976 ◽  
Vol 64 (1) ◽  
pp. 213 ◽  
Author(s):  
M. A. Pemadasa ◽  
P. H. Lovell
Keyword(s):  
Life Cycle ◽  
Vegetative Growth

scholarly journals A method for mapping germ line sequences in Tetrahymena thermophila using the polymerase chain reaction.

Genetics ◽  
1994 ◽  
Vol 137 (1) ◽  
pp. 95-106 ◽  
Author(s):  
D Cassidy-Hanley ◽  
M C Yao ◽  
P J Bruns
Keyword(s):  
Polymerase Chain Reaction ◽  
Dna Sequences ◽  
Tetrahymena Thermophila ◽  
Germ Line ◽  
Repetitive Sequences ◽  
Mapping Technique ◽  
Ciliated Protozoan ◽  
Chain Reaction ◽  
Polymerase Chain ◽  
Template Dna

Abstract A method for mapping DNA sequences to specific germinal chromosomes in the ciliated protozoan Tetrahymena thermophila has been developed. This mapping technique (PCR mapping) utilizes the polymerase chain reaction and template DNA derived from nullisomic strains to directly assign micronuclear DNA sequences to specific micronuclear chromosomes. Using this technique, a number of unique sequences and short repetitive sequences flanked by unique sequences have been mapped to four of the five germinal chromosomes.

scholarly journals Ultrastructure of Lobosphaera reniformis (Watanabe) Komárek et Fott (Chlorellales) from King George Island, South Shetland Islands, Antarctica

2014 ◽  
Vol 63 (2) ◽  
pp. 205-210 ◽  
Author(s):  
A. Massalski ◽  
T. Mrozińska ◽  
M. Olech
Keyword(s):  
Electron Microscopy ◽  
Life Cycle ◽  
South Shetland Islands ◽  
King George Island ◽  
Vegetative Cells ◽  
Shetland Islands ◽  
Complete Life Cycle ◽  
Laboratory Cultures ◽  
First Time

<i>Lobosphaera reniformis</i> (Wat.) Kom. et Fott (=<i>Chlorella reniformis</i> Wat.) so far known only from Japan, and Papua Island, was for the first time found in Antarctica (King George Island, South Shetland Islands). In laboratory cultures a complete life cycle was obtained, and most of its stages were followed by the electron microscopy. Reproduction is by morphologically different autospores. In some large vegetative cells two Golgi apparatuses lying side by side were observed.

scholarly journals Site-specific methylation of adenine in the nuclear genome of a eucaryote, Tetrahymena thermophila.

1986 ◽  
Vol 6 (7) ◽  
pp. 2364-2370 ◽  
Author(s):  
G S Harrison ◽  
R C Findly ◽  
K M Karrer
Keyword(s):  
Heat Shock ◽  
Protein Gene ◽  
De Novo ◽  
Tetrahymena Thermophila ◽  
Nuclear Genome ◽  
Histone H4 ◽  
Ciliated Protozoan ◽  
Site Specific ◽  
Logarithmic Growth ◽  
I Gene

DNA in the polyploid macronucleus of the ciliated protozoan Tetrahymena thermophila contains the modified base N6-methyladenine. We identified two GATC sites which are methylated in most or all of the 45 copies of the macronuclear genome. One site is 2 kilobases 5' to the histone H4-I gene, and the other is 5 kilobases 3' to the 73-kilodalton heat shock protein gene. These sites are de novo methylated between 10 and 16 h after initiation of conjugation, during macronuclear anlage development. The methylation states of these two GATC sites and four other unmethylated GATC sites do not change in the DNA of cells cultured under conditions which change the activity of the genes, including logarithmic growth, starvation, and heat shock.

Molecular cloning of casein kinase II alpha subunit from Dictyostelium discoideum and its expression in the life cycle

1992 ◽  
Vol 12 (12) ◽  
pp. 5711-5723
Author(s):  
U Kikkawa ◽  
S K Mann ◽  
R A Firtel ◽  
T Hunter
Keyword(s):  
Life Cycle ◽  
Dictyostelium Discoideum ◽  
Cdna Clone ◽  
Blot Analysis ◽  
Vegetative Growth ◽  
Casein Kinase Ii ◽  
Casein Kinase ◽  
Developmental Expression ◽  
Alpha Subunit ◽  
Alpha Gene

A Dictyostelium discoideum cDNA encoding an alpha-type subunit of casein kinase II was isolated, and its cDNA was used to study developmental expression of casein kinase II during the Dictyostelium life cycle. The 1.3-kb cDNA insert contained an open reading frame of 337 amino acids (M(r) 39,900). The deduced amino acid sequence has high homology with those of casein kinase II alpha subunits from other species. Genomic Southern blot analysis suggested that there is a single gene encoding casein kinase II alpha subunit in D. discoideum. Northern (RNA) blot analysis showed that the casein kinase II alpha-subunit gene is expressed constitutively as a 1.9-kb mRNA throughout vegetative growth and multicellular development. Casein kinase purified from normal vegetative cells contained a major protein band of approximately 36 kDa, which was recognized by antisera raised against rat testis casein kinase II. Comparison of the in vitro transcription/translation product of the alpha-subunit cDNA clone and the purified 36-kDa protein by partial proteolysis indicated that the isolated cDNA clone encodes the Dictyostelium casein kinase II alpha subunit. No protein corresponding to a beta subunit was detected in purified casein kinase. Immunoblot analysis using anti-rat casein kinase II sera showed that the alpha subunit of casein kinase II is expressed constitutively like its mRNA during the life cycle of D. discoideum. Casein kinase II activity measured by using a specific peptide substrate paralleled the level of alpha subunit detected by immunoblotting during the life cycle, with a maximum variation of approximately 2-fold. We were unable to obtain disruptants of the casein kinase II alpha gene, suggesting that there is a single casein kinase II alpha gene, which is essential for vegetative growth of D. discoideum.

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