Abnormalities in somite segmentation following heat shock to Xenopus embryos

Development ◽  
1976 ◽  
Vol 35 (3) ◽  
pp. 625-635
Author(s):  
Tom Elsdale ◽  
Murray Pearson ◽  
Margaret Whitehead
Keyword(s):  
Heat Shock ◽  
Wave Front ◽  
Sensitive Period ◽  
Temperature Sensitive ◽  
Cell Determination ◽  
Xenopus Embryos ◽  
Temporal Aspects ◽  
Two Sides ◽  
Mite Number

The typical abnormality induced by a 15 min shock at 37 °C is a single discrete length along the so mite file within which segmental boundaries are absent or irregular. The two sides of the same embryo present a similar but not necessarily identical appearance. Usually all the embryos in a treated batch show abnormalities of similar severity. Survival of treated embryos, the details of the visible malformations, and temporal aspects of the phenomenon have been studied. The results indicate a temperature sensitive period that traverses the neurula, from head to tail at about the same rate as the so mites form, but some hours beforehand. The temperature sensitive process is not associated with cell determination and differentiation, and there are reasons for thinking that the specification of the normal so mite number occurs independently. The results are discussed in relation to Cooke & Zeeman's model of a wave front inter-acting with an oscillator.

Analysis of the temperature-sensitive period of the short-1 mutation affecting stomatogenesis in Paramecium tetraurelia

1987 ◽  
Vol 88 (2) ◽  
pp. 241-250
Author(s):  
LAI-WA TAM ◽  
STEPHEN F. NG
Keyword(s):  
Heat Shock ◽  
Sexual Reproduction ◽  
Temperature Shift ◽  
High Sensitivity ◽  
Sensitive Period ◽  
Temperature Sensitive ◽  
Basal Bodies ◽  
Paramecium Tetraurelia ◽  
Membrane Growth ◽  
Development Temperature

Reduction in the length of the oral apparatus produced by the temperature-sensitive mutation short-1 (sh1) involved suppressed growth of the oral primordium in all stages of development. Temperature shift-up and heat-shock experiments revealed that the temperature-sensitive period of this mutation coincided with nearly the entire stomatogenic phase (stages 1–6) in sexual reproduction. Low- and high-sensitivity phases were noted, corresponding to the periods of slow (stages 1 and 2) and rapid (stage 3 to stage 6) elongation of the oral primordium, respectively. The action of sh1 is thus concentrated after stage 2. The mutation hypothetically results in defective membrane growth and extension in the oral primordium, leading to restriction in incorporation of basal bodies into the developing membranelles.

scholarly journals Rox3 and Rts1 Function in the Global Stress Response Pathway in Baker's Yeast

Genetics ◽  
1996 ◽  
Vol 142 (4) ◽  
pp. 1083-1093 ◽  
Author(s):  
Carlos C Evangelista ◽  
Ana M Rodriguez Torres ◽  
M Paullin Limbach ◽  
Richard S Zitomer
Keyword(s):  
Stress Response ◽  
Heat Shock ◽  
Osmotic Stress ◽  
Regulatory Element ◽  
Regulatory Region ◽  
Mitogen Activated Protein Kinase ◽  
Regulatory Subunit ◽  
Temperature Sensitive ◽  
Global Stress ◽  
Rna Accumulation

Abstract Yeast respond to a variety of stresses through a global stress response that is mediated by a number of signal transduction pathways and the cis-acting STRE DNA sequence. The CYC7 gene, encoding iso-2-cytochrome c, has been demonstrated to respond to heat shock, glucose starvation, approach-to-stationary phase, and, as we demonstrate here, to osmotic stress. This response was delayed in a the hogl-Δ1 strain implicating the Hog1 mitogen-activated protein kinase cascade, a known component of the global stress response. Deletion analysis of the CYC7 regulatory region suggested that three STRE elements were each capable of inducing the stress response. Mutations in the ROX3 gene prevented CYC7 RNA accumulation during heat shock and osmotic stress. ROX3 RNA levels were shown to be induced by stress through a novel regulatory element. A selection for high-copy suppressors of a ROX3 temperature-sensitive allele resulted in the isolation of RTS1, encoding a protein with homology to the B′ regulatory subunit of protein phosphatase 2A0. Deletion of RTS1 caused temperature and osmotic sensitivity and increased accumulation of CYC7 RNA under all conditions. Over-expression of this gene caused increased CYC7 RNA accumulation in rox3 mutants but not in wild-type cells.

scholarly journals MATERNAL-ZYGOTIC GENE INTERACTIONS DURING FORMATION OF THE DORSOVENTRAL PATTERN IN DROSOPHILA EMBRYOS

Genetics ◽  
1983 ◽  
Vol 105 (3) ◽  
pp. 615-632 ◽  
Author(s):  
Pat Simpson
Keyword(s):  
Early Embryo ◽  
Drosophila Embryo ◽  
Sensitive Period ◽  
Temperature Sensitive ◽  
Mutant Genotype ◽  
Dominant Phenotype ◽  
Zygotic Gene ◽  
Definition Of ◽  
Mutant Phenotypes ◽  
Dominant Lethality

ABSTRACT Maternal-zygotic interactions involving the three genes dorsal (dl), twist (twi) and snail (sna) are described. The results suggest that all three are involved in the process by which the dorsoventral pattern of the Drosophila embryo is established. First, the lethal embryonic mutant phenotypes are rather similar. In homozygous twi or sna embryos invagination of the ventral presumptive mesodermal cells fails to occur, and the resulting embryos are devoid of internal organs. This is very similar to the dominant phenotype described for dl; in the case of dl, however, the effect is a maternal one dependent on the mutant genotype of the female. Second, a synergistic interaction has been found whereby dominant lethality of twi  - or sna-bearing zygotes is observed in embryos derived from heterozygous dl females at high temperature. The temperature sensitivity of this interaction permitted definition of a temperature-sensitive period which is probably that of dl. This was found to extend from approximately 12 hr prior to oviposition to 2— 3 hr of embryogenesis. A zygotic action for the dl gene in addition to the maternal effect was revealed by the finding that extra doses of dl  + in the zygotes can partially rescue the dominant lethality of heterozygous twi embryos derived from heterozygous dl females. Two possible interpretations of the synergism are considered: (1) twi and sna are activated in the embryos as a result of positional signals placed in the egg as a consequence of the functioning of the dl gene during oogenesis and, thus, play a role in embryonic determination. (2) The gene products of dl  + and twi  + (or sna  +) combine to produce a functional molecule that is involved in the specification of dorsoventral pattern in the early embryo.

scholarly journals The Skn7 Response Regulator ofSaccharomyces cerevisiaeInteracts with Hsf1 In Vivo and Is Required for the Induction of Heat Shock Genes by Oxidative Stress

2000 ◽  
Vol 11 (7) ◽  
pp. 2335-2347 ◽  
Author(s):  
Desmond C. Raitt ◽  
Anthony L. Johnson ◽  
Alexander M. Erkine ◽  
Kozo Makino ◽  
Brian Morgan ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Heat Shock ◽  
Response Regulator ◽  
Coiled Coil ◽  
Normal Growth ◽  
Temperature Sensitive ◽  
Regulatory Sequences ◽  
Heat Shock Genes

The Skn7 response regulator has previously been shown to play a role in the induction of stress-responsive genes in yeast, e.g., in the induction of the thioredoxin gene in response to hydrogen peroxide. The yeast Heat Shock Factor, Hsf1, is central to the induction of another set of stress-inducible genes, namely the heat shock genes. These two regulatory trans-activators, Hsf1 and Skn7, share certain structural homologies, particularly in their DNA-binding domains and the presence of adjacent regions of coiled-coil structure, which are known to mediate protein–protein interactions. Here, we provide evidence that Hsf1 and Skn7 interact in vitro and in vivo and we show that Skn7 can bind to the same regulatory sequences as Hsf1, namely heat shock elements. Furthermore, we demonstrate that a strain deleted for the SKN7 gene and containing a temperature-sensitive mutation in Hsf1 is hypersensitive to oxidative stress. Our data suggest that Skn7 and Hsf1 cooperate to achieve maximal induction of heat shock genes in response specifically to oxidative stress. We further show that, like Hsf1, Skn7 can interact with itself and is localized to the nucleus under normal growth conditions as well as during oxidative stress.

Impaired induction of heat shock protein implicated in decreased thermotolerance in a temperature-sensitive multinucleated cell line

1998 ◽  
Vol 437 (1) ◽  
pp. 15-20 ◽  
Author(s):  
Y. Cao ◽  
Takaaki Matsumoto ◽  
Katsuaki Motomura ◽  
Akira Ohtsuru ◽  
Shunichi Yamashita ◽  
...  
Keyword(s):  
Heat Shock ◽  
Heat Shock Protein ◽  
Cell Line ◽  
Temperature Sensitive ◽  
Multinucleated Cell

Expression of a mammalian Na+/H+ antiporter in Saccharomyces cerevisiae

1999 ◽  
Vol 77 (1) ◽  
pp. 25-31 ◽  
Author(s):  
Mónica Montero-Lomelí ◽  
Anna L Okorokova Façanha.
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Heat Shock ◽  
Subcellular Fractionation ◽  
Temperature Sensitive ◽  
Wild Type ◽  
Coding Region ◽  
Phosphatidylcholine Liposomes ◽  
Yeast Transformants ◽  
Wild Type Yeast ◽  
Membrane Region

The basolateral Na+/H+ antiporter (NHE) from LLC-PK1 cells was expressed in Saccharomyces cerevisiae. Two different strategies were tested for expression. In the first, we used a yeast strain that contains a temperature-sensitive mutation in the SEC-6 gene, whose product is required for the fusion of secretory vesicles with the plasma membrane. This strain was transformed with a vector containing the coding region of the NHE1 isoform under control of a heat shock (HS) promoter (pYNHE1-HS). In the second strategy, we replaced the heat shock promoter from pYNHE1-HS with a galactose (GAL) promoter (pYNHEI-GAL) and transformed wild-type yeast. In both cases, Northern blots demonstrated a transcript that hybridized against a probe containing the membrane region of the exchanger. When an antibody against the last 40 amino acids of the carboxy-terminus of NHE1 was used for immuno-blots, a protein with a Mr of 73 000 was seen in total membranes from both yeast transformants. Subcellular fractionation revealed that NHE1 was expressed in the endoplasmic reticulum. In the case of the pYNHEI-GAL transformant, the 100 000 × g membrane pellet was reconstituted in phosphatidylcholine liposomes, and ethylisopropyl-amiloride-sensitive Na+/H+ exchange was observed. These results have paved the way for expression of the Na+/H+ exchanger in a genetically well-known microorganism.Key words: Na+/H+ exchanger, NHE1, expression, yeast.

scholarly journals Heterotaxy in Caenorhabditis : widespread natural variation in left–right arrangement of the major organs

2016 ◽  
Vol 371 (1710) ◽  
pp. 20150404 ◽  
Author(s):  
Melissa R. Alcorn ◽  
Davon C. Callander ◽  
Agustín López-Santos ◽  
Yamila N. Torres Cleuren ◽  
Bilge Birsoy ◽  
...  
Keyword(s):  
Genome Wide Association Study ◽  
Recombinant Inbred Lines ◽  
Sensitive Period ◽  
Temperature Sensitive ◽  
Internal Organs ◽  
Genome Wide ◽  
A Genome ◽  
Natural Isolates ◽  
Left Right Asymmetry ◽  
Genomic Regions

Although the arrangement of internal organs in most metazoans is profoundly left–right (L/R) asymmetric with a predominant handedness, rare individuals show full (mirror-symmetric) or partial (heterotaxy) reversals. While the nematode Caenorhabditis elegans is known for its highly determinate development, including stereotyped L/R organ handedness, we found that L/R asymmetry of the major organs, the gut and gonad, varies among natural isolates of the species in both males and hermaphrodites. In hermaphrodites, heterotaxy can involve one or both bilaterally asymmetric gonad arms. Male heterotaxy is probably not attributable to relaxed selection in this hermaphroditic species, as it is also seen in gonochoristic Caenorhabditis species. Heterotaxy increases in many isolates at elevated temperature, with one showing a pregastrulation temperature-sensitive period, suggesting a very early embryonic or germline effect on this much later developmental outcome. A genome-wide association study of 100 isolates showed that male heterotaxy is associated with three genomic regions. Analysis of recombinant inbred lines suggests that a small number of loci are responsible for the observed variation. These findings reveal that heterotaxy is a widely varying quantitative trait in an animal with an otherwise highly stereotyped anatomy, demonstrating unexpected plasticity in an L/R arrangement of the major organs even in a simple animal. This article is part of the themed issue ‘Provocative questions in left–right asymmetry’.

MEIOSIS IN COPRINUS: VI. THE CONTROL OF THE INITIATION OF MEIOSIS

1974 ◽  
Vol 16 (1) ◽  
pp. 155-164 ◽  
Author(s):  
B. C. Lu
Keyword(s):  
Electron Microscopy ◽  
High Temperature ◽  
Mycelial Growth ◽  
Dark Period ◽  
Continuous Light ◽  
Sensitive Period ◽  
Temperature Sensitive ◽  
Light Cycle ◽  
Sensitive Stage ◽  
Dark Regime

Meiosis in Coprinus lagopus is normally initiated at night under normal diurnal conditions. This timing can be shifted to 0900-1000 h by using a 16h light-8h dark regime with the light cycle commencing at 1600 h. For the initiation of meiosis, C. lagopus is temperature sensitive (35 C) under continuous light. The temperature sensitivity can be overcome by a dark period. The sensitive period occurs within 7 h of karyogmay. Only the first 2 h, however, are sensitive to light and high temperature. A shift-up to restrictive conditions before the sensitive stage effectively arrests the process leading to karyogamy. The arrest is reversible within 20 h. Upon returning to a 25 C chamber, karyogamy begins in 6 h in all basidiocarps. Thus using this technique accurate control of the initiation of meiosis can be achieved. Howeevr, prolonged arrest beyond 16 h causes the basidia to revert to mitosis and mycelial growth. The nucleolus is reduced in size and exhibits a large vacuole and a lack of granular components as shown by electron microscopy.

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