scholarly journals TEMPERATURE-SENSITIVE MUTATIONS OF THE NOTCH LOCUS IN DROSOPHILA MELANOGASTER

Genetics ◽  
1975 ◽  
Vol 81 (1) ◽  
pp. 143-162 ◽  
Author(s):  
David L Shellenbarger ◽  
J Dawson Mohler
Keyword(s):  
Temperature Shift ◽  
Temperature Sensitive ◽  
Spatial Differences ◽  
Region Temperature ◽  
Complex Locus ◽  
Notch Locus ◽  
Temporal And Spatial ◽  
Chemical Conditions ◽  
Interallelic Complementation ◽  
The Right

ABSTRACT Temperature-conditional mutations of the Notch locus were characterized in an attempt to understand the organization of a "complex locus" and the control of its function in development. Among 21 newly induced Notch alleles, about one-half are temperature-conditional for some effects, and three are temperature-sensitive for viability. One temperature-sensitive lethal, l(1)Nts1, is functionally non-complementing for all known effects of Notch locus mutations and maps at a single site within the locus. Among the existing alleles involved in complex patterns of interallelic complementation, Ax59d5 is found to be temperature-sensitive, while fag, spl, and l(1)N are temperature-independent. Whereas temperature-sensitive alleles map predominantly to the right-most fifth of the locus, fag, spl, and l(1)N are known to map to the left of this region. Temperature-shift experiments demonstrate that fag, spl, and l(1)N cause defects at specific, non-overlapping times in development.—We conclude (1) that the Notch locus is a single cistron (responsible for a single functional molecule, presumably a polypeptide); (2) that the right-most fifth of the locus is, at least in part, the region involved in coding for the Notch product; (3) that the complexity of interallelic complementation is a developmental effect of mutations that cause defects at selected times and spaces, and that complementation occurs because the mutant defects are temporally and spatially non-overlapping; and (4) that mutants express selected defects due to critical temporal and spatial differences in the chemical conditions controlling the synthesis or function of the Notch product. The complexity of the locus appears to reside in controlling the expression (synthesis or function) of the Notch product in development.

scholarly journals Genetic Analysis of the Heterochromatin of Chromosome 3 in Drosophila Melanogaster. II. Vital Loci Identified through Ems Mutagenesis.

Genetics ◽  
1988 ◽  
Vol 120 (2) ◽  
pp. 519-532
Author(s):  
G E Marchant ◽  
D G Holm
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Analysis ◽  
Single Copy ◽  
Chromosome 3 ◽  
Temperature Sensitive ◽  
Chromosome 2 ◽  
Complementation Groups ◽  
Sensitive Allele ◽  
Interallelic Complementation ◽  
The Right

Abstract Chromosome 3 of Drosophila melanogaster contains the last major blocks of heterochromatin in this species to be genetically analyzed. Deficiencies of heterochromatin generated through the detachment of compound-3 chromosomes revealed the presence of vital loci in the heterochromatin of chromosome 3, but an extensive complementation analysis with various combinations of lethal and nonlethal detachment products gave no evidence of tandemly repeated vital genes in this region. These findings indicate that the heterochromatin of chromosome 3 is genetically similar to that of chromosome 2. A more thorough genetic analysis of the heterochromatic regions has been carried out using the chemical mutagen ethyl methanesulfonate (EMS). Seventy-five EMS-induced lethals allelic to loci uncovered by detachment-product deficiencies were recovered and tested for complementation. In total, 12 complementation groups were identified, ten in the heterochromatin to the left of the centromere and two to the right. All but two complementation groups in the left heterochromatic block could be identified as separate loci through deficiency mapping. The interallelic complementation observed between some EMS-induced lethals, as well as the recovery of a temperature-sensitive allele for each of the two loci, provided further evidence that single-copy, transcribed vital genes reside in the heterochromatin of chromosome 3. Cytological analysis of three detachment-product deficiencies provided evidence that at least some of the genes uncovered in this study are located in the most distal segments of the heterochromatin in both arms. This study provides a detailed genetic analysis of chromosome 3 heterochromatin and offers further information on the genetic nature and heterogeneity of Drosophila heterochromatin.

Memories for the Return? Remembering the Nakba by the First Generation of Palestinian Refugees in Syria

2017 ◽  
Vol 16 (2) ◽  
pp. 177-192 ◽  
Author(s):  
Anaheed Al-Hardan
Keyword(s):  
First Generation ◽  
Palestinian Refugees ◽  
Oslo Accords ◽  
Right Of Return ◽  
Palestinian Refugee ◽  
Temporal And Spatial ◽  
The Right ◽  
Political Realities ◽  
The Way

The 1948 Nakba has, in light of the 1993 Oslo Accords and Palestinian refugee activists' mobilisation around the right of return, taken on a new-found centrality and importance in Palestinian refugee communities. Closely-related to this, members of the ‘Generation of Palestine’, the only individuals who can recollect Nakba memories, have come to be seen as the guardians of memories that are eventually to reclaim the homeland. These historical, social and political realities are deeply rooted in the ways in which the few remaining members of the generation of Palestine recollect 1948. Moreover, as members of communities that were destroyed in Palestine, and whose common and temporal and spatial frameworks were non-linearly constituted anew in Syria, one of the multiples meanings of the Nakba today can be found in the way the refugee communities perceive and define this generation.

scholarly journals Identification and Characterization of Genes That Interact With lin-12 in Caenorhabditis elegans

Genetics ◽  
1997 ◽  
Vol 147 (4) ◽  
pp. 1675-1695 ◽  
Author(s):  
Frans E Tax ◽  
James H Thomas ◽  
Edwin L Ferguson ◽  
H Robert Horvitzt
Keyword(s):  
Cell Fate ◽  
Low Frequency ◽  
Signal Transduction Pathway ◽  
Temperature Shift ◽  
Egg Laying ◽  
Null Alleles ◽  
Temperature Sensitive ◽  
Loss Of Function ◽  
Gain Of Function ◽  
Suppressor Mutations

Abstract We identified and characterized 14 extragenic mutations that suppressed the dominant egg-laying defect of certain lin-12 gain-of-function mutations. These suppressors defined seven genes: sup-l7, lag-2, sel-4, sel-5, sel-6, sel-7 and sel-8. Mutations in six of the genes are recessive suppressors, whereas the two mutations that define the seventh gene, lag-2, are semi-dominant suppressors. These suppressor mutations were able to suppress other lin-12 gain-of-function mutations. The suppressor mutations arose at a very low frequency per gene, 10-50 times below the typical loss-of-function mutation frequency. The suppressor mutations in sup1 7 and lag-2 were shown to be rare non-null alleles, and we present evidence that null mutations in these two genes cause lethality. Temperature-shift studies for two suppressor genes, sup1 7and lag-2, suggest that both genes act at approximately the same time as lin-12in specifying a cell fate. Suppressor alleles of six of these genes enhanced a temperature-sensitive loss-of-function allele of glp-1, a gene related to lin-12 in structure and function. Our analysis of these suppressors suggests that the majority of these genes are part of a shared lin-12/glp-1 signal transduction pathway, or act to regulate the expression or stability of lin-12 and glp-1.

Recherches sur le rôle de la température dans la réalisation du phénotype chez des embryons de l'Amphibien Pleurodeles waltlii homozygotes pour la mutation thermosensible ac (ascite caudale)

Development ◽  
1975 ◽  
Vol 34 (1) ◽  
pp. 221-252
Author(s):  
Par Maria Fernandez ◽  
Jean-Claude Beetschen
Keyword(s):  
Embryonic Development ◽  
Developmental Stages ◽  
Fluid Collection ◽  
Temperature Shift ◽  
Temperature Sensitive ◽  
Tail Bud ◽  
Dorsal Fin ◽  
Second Shift ◽  
Pleurodeles Waltlii

1. At the feeding stage (st. 38), a high percentage (79 %) of Pleurodeles homozygous ac/ac larvae show bent tails after a persistent ascitic blister in the dorsal part of the fin, when embryonic development occurred at 12°C; about only 25 % of them are affected by abdominal and pericardic ascites; about 40 % can feed and survive. The larval phenotype is very different when embryonic development occurred at 23 °C, in which case tail growth appears to be normal, but 95 % larvae die, due to ascitic fluid collection in the abdominal and heart regions, marked anaemia and microcephaly. 2. The exchange of posterior neural plates and dorso-lateral epidermis between normal and mutant neurulae has shown that the localization of the blister in the dorsal fin is not dependent on autonomous properties of the mutant dorsal tissues, but should be considered as resulting from general disturbances in the mutant organism. 3. Experiments were performed, involving a temperature shift from 12 to 23°C or 23 to 12°C, occurring at various developmental stages from the end of gastrulation (stage 13) to the stage of spontaneous embryonic muscle contractions (stage 26). When the temperature shift was applied after the end of neurulation (stage 21), the caudal phenotype was statistically similar to that of larvae which had been bred continuously at the first temperature. Thus temperature-sensitive phases can be characterized between neurula stages 15 and 18 (for a 12–23° shift) or 15 and 21 (for a 23–12° shift). Similarly, abdominal ascites can be induced when embryos are kept at 23 °C till stage 23 (early tail-bud) only, and occurs much less frequently when embryos are kept at 12°C till stage 23 and then transferred to 23°C. 4. It could be concluded from these experiments that the caudal mutant phenotype is already temperature-determined during neurulation, before stage 21. Nevertheless, double temperature-shift experiments showed that the second shift could modify the results which would be obtained if the first shift only occurred. Paradoxical results were obtained, more than 90 % of the tail phenotypes being of the ‘warm type’ when the embryos were first kept at 12°C, then shifted up to 23 °C between stages 22 and 26, and shifted down again to 12°C. Such a treatment markedly lowers the percentage of bent tails (‘cold type’) from the percentage which would occur if ac/ac embryos were constantly kept at 23 °C after stage 21, but this longer warm treatment is of no effect of itself as compared to the case when the whole development occurs at 12°C (bent tails are predominant in this latter case). Thus, whereas the early determination of the position of the caudal blister can be considered as a stable phenomenon under given temperature conditions, it is not irreversible. 5. As compared to cold-bred larvae, thrice as many completely anaemic larvae (66 %) were obtained from ac/ac embryos kept at 23 °C between stages 21 and 26; this offers an opportunity for the experimental study of this anaemia. 6. Implications of these results for further analysis of temperature-sensitive mutations in cold-blooded vertebrates are suggested.

Temperature-sensitive DNA mutant of Chinese hamster ovary cells with a thermolabile ribonucleotide reductase activity

1990 ◽  
Vol 10 (11) ◽  
pp. 5688-5699
Author(s):  
B E Wojcik ◽  
J J Dermody ◽  
H L Ozer ◽  
B Mun ◽  
C K Mathews
Keyword(s):  
Dna Synthesis ◽  
Ribonucleotide Reductase ◽  
Chinese Hamster Ovary ◽  
Reductase Activity ◽  
Chinese Hamster ◽  
Temperature Shift ◽  
Ovary Cell ◽  
Temperature Sensitive ◽  
Dntp Pool ◽  
Ribonucleotide Reductase Activity

JB3-B is a Chinese hamster ovary cell mutant previously shown to be temperature sensitive for DNA replication (J. J. Dermody, B. E. Wojcik, H. Du, and H. L. Ozer, Mol. Cell. Biol. 6:4594-4601, 1986). It was chosen for detailed study because of its novel property of inhibiting both polyomavirus and adenovirus DNA synthesis in a temperature-dependent manner. Pulse-labeling studies demonstrated a defect in the rate of adenovirus DNA synthesis. Measurement of deoxyribonucleoside triphosphate (dNTP) pools as a function of time after shift of uninfected cultures from 33 to 39 degrees C revealed that all four dNTP pools declined at similar rates in extracts prepared either from whole cells or from rapidly isolated nuclei. Ribonucleoside triphosphate pools were unaffected by a temperature shift, ruling out the possibility that the mutation affects nucleoside diphosphokinase. However, ribonucleotide reductase activity, as measured in extracts, declined after cell cultures underwent a temperature shift, in parallel with the decline in dNTP pool sizes. Moreover, the activity of cell extracts was thermolabile in vitro, consistent with the model that the JB3-B mutation affects the structural gene for one of the ribonucleotide reductase subunits. The kinetics of dNTP pool size changes after temperature shift are quite distinct from those reported after inhibition of ribonucleotide reductase with hydroxyurea. An indirect effect on ribonucleotide reductase activity in JB3-B has not been excluded since human sequences other than those encoding the enzyme subunits can correct the temperature-sensitive growth defect in the mutant.

Dissolved Inorganic Nitrogen Fluxes at Sediment-Water Interface in Yangtze Estuarine Tidal Flat

2013 ◽  
Vol 726-731 ◽  
pp. 288-295 ◽  
Author(s):  
Huan Guang Deng ◽  
Dong Qi Wang ◽  
Zhen Lou Chen
Keyword(s):  
Tidal Flat ◽  
Environmental Gradients ◽  
Inorganic Nitrogen ◽  
Yangtze Estuary ◽  
Water Interface ◽  
Dissolved Inorganic Nitrogen ◽  
Overlying Water ◽  
Spatial Differences ◽  
Estuary Sediment ◽  
Temporal And Spatial

Yangtze estuary data, collected over three years, indicates that the temporal and spatial distributions of the environmental gradients reflect complicated seasonal changes and spatial differences in the exchange flux of the dissolved inorganic nitrogen (DIN= NH4++ NO3-+ NO2-) across the sediment-water interface. Overall in northern sites of Yangtze estuary, sediment was a source of ammonium (NH4+) (-3.67~10.65 mmol·m-2·d-1) probably because of higher salinities. Sediment was a sink for NH4+ in southern sites (-18.45~3.33 mmol·m-2·d-1) during most years. The exchange behavior of nitrate (NO3-) showed temporal and spatial variation from the upper to lower estuary and ranged from-32.8 mmol·m-2·d-1 to 35.8 mmol·m-2·d-1. The interface exchange direction of ammonium was affected by NH4+ concentration, but the relationship between NO3- concentration and the direction of flux was not obvious. The concentration of nitrite (NO2-) was very low and its interface flux was not related to DIN concentration. Overall, the sediment of Yangtze Estuarine tidal flat was a source of DIN to overlying water in the spring, but a sink for DIN during the other three seasons of the year.

Isolation and characterization of a variant myoblast cell line that is temperature sensitive for differentiation

1988 ◽  
Vol 8 (6) ◽  
pp. 2335-2341
Author(s):  
R J Akhurst ◽  
N B Flavin ◽  
J Worden
Keyword(s):  
Cell Line ◽  
Progenitor Cell ◽  
Temperature Shift ◽  
Temperature Sensitive ◽  
Isolation And Characterization ◽  
New Variant ◽  
Myoblast Cell Line ◽  
Myoblast Cell ◽  
Progenitor Cell Line

A new variant rat myogenic cell line, ts485, was isolated by subcloning the cell line ts3b2 (H. T. Nguyen, R. M. Medford, and B. Nadal-Ginard, Cell 34:281-293, 1983). Unlike the progenitor cell line, ts485 was thermosensitive for differentiation. Experiments with conditioned medium suggested that diffusible extracellular factors were not involved in dictating the differential phenotypes of ts485 cells cultured at the permissive and nonpermissive temperatures. Temperature shift experiments performed on cultures of ts485 cells indicated that the temperature-sensitive lesion was in a factor active during the growth phase and required to trigger a cascade of events leading to terminal differentiation.

Temporal and Spatial Aspects of Pointing Gestures

2010 ◽  
pp. 166-186
Author(s):  
Christian Müller-Tomfelde ◽  
Fang Chen
Keyword(s):  
Dwell Time ◽  
Spatial Organisation ◽  
Core Element ◽  
Temporal Domain ◽  
Pointing Gestures ◽  
Temporal And Spatial ◽  
The Right ◽  
Pointing Gesture ◽  
Human Pointing

The detailed and profound understanding of the temporal and spatial organisation of human pointing actions is key to enable developers to build applications that successfully incorporate multimodal human computer interaction. Rather than discussing an ideal detection method for manual pointing we will discuss crucial aspects of pointing actions in time and space to develop the right solution for a particular application. One core element of pointing in the temporal domain is the so called dwell-time, the time span that people remain nearly motionless during pointing at objects to express their intention. We also discuss important findings about the spatial characteristics of the target representation for the pointing gesture.The findings foster better understanding of the role of pointing gestures in combination with other modalities and inform developer with substantial knowledge about the temporal-spatial organisation of the pointing gesture.

scholarly journals Temporal and spatial differences in three-egg clutch frequency of the African Black Oystercatcher

Ostrich ◽  
2015 ◽  
Vol 86 (1-2) ◽  
pp. 35-41 ◽  
Author(s):  
Dane M Paijmans ◽  
Douglas Loewenthal ◽  
Peter G Ryan ◽  
Philip AR Hockey
Keyword(s):  
Spatial Differences ◽  
African Black ◽  
Temporal And Spatial
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