Cell culture of individual Drosophila embryos

Development ◽  
1978 ◽  
Vol 45 (1) ◽  
pp. 173-187
Author(s):  
David P. Cross ◽  
James H. Sang
Keyword(s):  
Cell Cultures ◽  
Fat Body ◽  
Subsequent Development ◽  
Cell Types ◽  
Mixed Cultures ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Permissive Temperature ◽  
Wild Type

Results are reported from the culturing in vitro of cells from individual early gastrulae of the following four groups of X-linked embryonic lethal mutants of Drosophila melanogaster. (1) Notch lethals. Five Notch mutants were studied which have been reported to give similar abnormalities in whole embryos: the nervous system displays a three-fold hypertrophy as part of a shift in the pattern of differentiation within ectodermal derivatives, and mesodermal derivatives do not differentiate. An hypertrophy of nerve was found in cell cultures prepared from embryos of all five mutants. In addition, four of the five alleles consistently gave abnormalities of muscle differentiation: when compared to controls, Notch cultures had a reduced frequency of myotubes, and displayed unusual clusters of myocytes which had either failed to fuse or had fused incompletely. Results from mixed cultures prepared from two embryos were consistent with the autonomous expression of nerve and muscle abnormalities by Notch-8 cells in the presence of wild-type cells. It is argued that the Notch locus has a direct role in the differentiation of both nerve and muscle. (2) white deficiencies. Cells carrying either of two deficiencies gave a clear-cut pattern of abnormalities: initial cellular differentiations were normal, but nerve, muscle and fat-body cells progressively deteriorated during the culture period. Mixed cultures showed that wild-type cells could not ‘rescue’ mutant muscle and fat-body cells; however, the status of the autonomy of mutant nerve abnormalities in these cultures was unclear. Both white deficiencies remove cytological band 3C1, and this permits a comparison of results with those from cultures of cells from Notch-8 embryos (also deficient for 3C1). Abnormalities displayed in cultures of the two types of mutant show no overlap. Therefore no consistent cellular abnormality can be attributed to absence of band 3C1. (3) lethal{l)myospheroid. In contrast to earlier observations on in vitro cell cultures (Donady & Seecof, 1972) muscle was seen to differentiate, though its morphology was extremely abnormal. Observations indicated that all cell types within the cultures had poor properties of adhesion to a glass substrate. It is argued that the observed abnormalities are not consistent with a mutant lesion which is restricted to the basement membrane (contra Wright, 1960), and that all cell types carry a basic defect which may reside in the cell membrane. (4) shibirets alleles. Cultures of two temperature-sensitive lethal shibire alleles (shits1, shits3) were normal at the permissive temperature of 22 °C. At the restrictive temperature (29 °C) early cell differentiation was normal but subsequent development was blocked. This blockage could be partially reversed by shifting cultures to the permissive temperature after as much as 10 days exposure to the high temperature. It is suggested that shits cells are mutant in a process which is basic to several cell types.

Correction of the defect in initiation of DNA replication in a temperature-sensitive mutant hamster cell line by in vitro addition of extracts from normal cells

1985 ◽  
Vol 5 (4) ◽  
pp. 902-905
Author(s):  
M Narkhammar ◽  
R Hand
Keyword(s):  
Cell Line ◽  
Nuclear Extract ◽  
Cell Extract ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Permissive Temperature ◽  
Wild Type ◽  
Whole Cell ◽  
Mutant Cells

ts BN-2 is a temperature-sensitive hamster cell line that is defective in DNA synthesis at the restrictive temperature. The mutant expresses its defect during in vitro replication in whole-cell lysates. Addition of a high-salt-concentration extract from wild-type BHK-21, revertant RBN-2, or CHO cells to mutant cells lysed with 0.01% Brij 58 increased the activity in the mutant three- to fourfold, so that it reached 85% of the control value, and restored replicative synthesis. The presence of extract had an insignificant effect on wild-type and revertant replication and on mutant replication at the permissive temperature. Extract prepared from mutant cells was less effective than the wild-type cell extract was. Also, the stimulatory activity was more heat labile in the mutant than in the wild-type extract. Nuclear extract was as active as whole-cell extract.

scholarly journals Correction of the defect in initiation of DNA replication in a temperature-sensitive mutant hamster cell line by in vitro addition of extracts from normal cells.

1985 ◽  
Vol 5 (4) ◽  
pp. 902-905 ◽  
Author(s):  
M Narkhammar ◽  
R Hand
Keyword(s):  
Cell Line ◽  
Nuclear Extract ◽  
Cell Extract ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Permissive Temperature ◽  
Wild Type ◽  
Whole Cell ◽  
Mutant Cells

ts BN-2 is a temperature-sensitive hamster cell line that is defective in DNA synthesis at the restrictive temperature. The mutant expresses its defect during in vitro replication in whole-cell lysates. Addition of a high-salt-concentration extract from wild-type BHK-21, revertant RBN-2, or CHO cells to mutant cells lysed with 0.01% Brij 58 increased the activity in the mutant three- to fourfold, so that it reached 85% of the control value, and restored replicative synthesis. The presence of extract had an insignificant effect on wild-type and revertant replication and on mutant replication at the permissive temperature. Extract prepared from mutant cells was less effective than the wild-type cell extract was. Also, the stimulatory activity was more heat labile in the mutant than in the wild-type extract. Nuclear extract was as active as whole-cell extract.

scholarly journals Enzymatic Defects of the nsP2 Proteins of Semliki Forest Virus Temperature-Sensitive Mutants

2007 ◽  
Vol 81 (6) ◽  
pp. 2849-2860 ◽  
Author(s):  
Giuseppe Balistreri ◽  
Javier Caldentey ◽  
Leevi Kääriäinen ◽  
Tero Ahola
Keyword(s):  
Protease Activity ◽  
Semliki Forest Virus ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Helicase Domain ◽  
Permissive Temperature ◽  
Protease Domain ◽  
Rna Triphosphatase ◽  
Interdomain Interactions

ABSTRACT We have analyzed the biochemical consequences of mutations that affect viral RNA synthesis in Semliki Forest virus temperature-sensitive (ts) mutants. Of the six mutations mapping in the multifunctional replicase protein nsP2, three were located in the N-terminal helicase region and three were in the C-terminal protease domain. Wild-type and mutant nsP2s were expressed, purified, and assayed for nucleotide triphosphatase (NTPase), RNA triphosphatase (RTPase), and protease activities in vitro at 24°C and 35°C. The protease domain mutants (ts4, ts6, and ts11) had reduced protease activity at 35°C but displayed normal NTPase and RTPase. The helicase domain mutation ts1 did not have enzymatic consequences, whereas ts13a and ts9 reduced both NTPase and protease activities but in different and mutant-specific ways. The effects of these helicase domain mutants on protease function suggest interdomain interactions within nsP2. NTPase activity was not directly required for protease activity. The similarities of the NTPase and RTPase results, as well as competition experiments, suggest that these two reactions utilize the same active site. The mutations were also studied in recombinant viruses first cultivated at the permissive temperature and then shifted up to the restrictive temperature. Processing of the nonstructural polyprotein was generally retarded in cells infected with viruses carrying the ts4, ts6, ts11, and ts13a mutations, and a specific defect appeared in ts9. All mutations except ts13a were associated with a large reduction in the production of the subgenomic 26S mRNA, indicating that both protease and helicase domains influence the recognition of the subgenomic promoter during virus replication.

Adenovirus core proteins

1983 ◽  
Vol 29 (2) ◽  
pp. 235-241 ◽  
Author(s):  
Joseph M. Weber ◽  
Govindranathsing Khittoo ◽  
A. Rashid Bhatti
Keyword(s):  
Molecular Weight ◽  
Structural Proteins ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Wild Type ◽  
Core Proteins

Advenovirus type 2 core proteins were studied with the aid of temperature-sensitive (ts) mutants affecting them. Cores prepared from wild-type virions with pyridine contained the structural proteins IVa2, V, VII, and X. Cores from the H2ts3 mutant contained an altered polypeptide V (50 K) of higher molecular weight and additional peptides. Ts1 virions produced at the restrictive temperature contained precores with proteins IVa2, V, pre-VI, pre-VII, and 11 K. This precore could be matured to a wild-type-like core by the adenovirus endoprotease. Of these core proteins only V, pre-VI, pre-VII, VII, and 11 K could be shown to reassociate in vitro with double-stranded heterologous DNA. Proteins IVa2 and X may bind to these core proteins rather than to the DNA directly.

scholarly journals Myristic acid auxotrophy caused by mutation of S. cerevisiae myristoyl-CoA:protein N-myristoyltransferase.

1991 ◽  
Vol 113 (6) ◽  
pp. 1313-1330 ◽  
Author(s):  
R J Duronio ◽  
D A Rudnick ◽  
R L Johnson ◽  
D R Johnson ◽  
J I Gordon
Keyword(s):  
Myristic Acid ◽  
Fatty Acid Synthetase ◽  
Catalytic Efficiency ◽  
Kinetic Studies ◽  
Fold Increase ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Permissive Temperature ◽  
Myristoyl Coa

The S. cerevisiae myristoyl-CoA:protein N-myristoyltransferase gene (NMT1) is essential for vegetative growth. NMT1 was found to be allelic with a previously described, but unmapped and unidentified mutation that causes myristic acid (C14:0) auxotrophy. The mutant (nmt1-181) is temperature sensitive, but growth at the restrictive temperature (36 degrees C) is rescued with exogenous C14:0. Several analogues of myristate with single oxygen or sulfur for methylene group substitutions partially complement the phenotype, while others inhibit growth even at the permissive temperature (24 degrees C). Cerulenin, a fatty acid synthetase inhibitor, also prevents growth of the mutant at 24 degrees C. Complementation of growth at 36 degrees C by exogenous fatty acids is blocked by a mutation affecting the acyl:CoA synthetase gene. The nmt1-181 allele contains a single missense mutation of the 455 residue acyltransferase that results in a Gly451----Asp substitution. Analyses of several intragenic suppressors suggest that Gly451 is critically involved in NMT catalysis. In vitro kinetic studies with purified mutant enzyme revealed a 10-fold increase in the apparent Km for myristoyl-CoA at 36 degrees C, relative to wild-type, that contributes to an observed 200-fold reduction in catalytic efficiency. Together, the data indicate that nmt-181 represents a sensitive reporter of the myristoyl-CoA pools utilized by NMT.

scholarly journals Codon Deletions in the Influenza A Virus PA Gene Generate Temperature-Sensitive Viruses

2016 ◽  
Vol 90 (7) ◽  
pp. 3684-3693 ◽  
Author(s):  
Léa Meyer ◽  
Alix Sausset ◽  
Laura Sedano ◽  
Bruno Da Costa ◽  
Ronan Le Goffic ◽  
...  
Keyword(s):  
Influenza Virus ◽  
Rna Polymerase ◽  
Influenza A Virus ◽  
Influenza A ◽  
Wild Type Virus ◽  
Deletion Mutants ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Wild Type

ABSTRACTThe influenza virus RNA-dependent RNA polymerase, which is composed of three subunits, PB1, PB2, and PA, catalyzes genome replication and transcription within the cell nucleus. The PA linker (residues 197 to 256) can be altered by nucleotide substitutions to engineer temperature-sensitive (ts), attenuated mutants that display a defect in the transport of the PA–PB1 complex to the nucleus at a restrictive temperature. In this study, we investigated the ability of the PA linker to tolerate deletion mutations for furtherin vitroandin vivocharacterization. Four viable mutants with single-codon deletions were generated; all of them exhibited atsphenotype that was associated with the reduced efficiency of replication/transcription of a pseudoviral reporter RNA in a minireplicon assay. Using fluorescently tagged PB1, we observed that the deletion mutants did not efficiently recruit PB1 to reach the nucleus at a restrictive temperature (39.5°C). Mouse infections showed that the four mutants were attenuated and induced antibodies that were able to protect mice from challenge with a lethal homologous wild-type virus. Serialin vitropassages of two deletion mutants at 39.5°C and 37°C did not allow the restoration of a wild-type phenotype among virus progeny. Thus, our results identify codons that can be deleted in the PA gene to engineer genetically stabletsmutants that could be used to design novel attenuated vaccines.IMPORTANCEIn order to generate genetically stable live influenza A virus vaccines, we constructed viruses with single-codon deletions in a discrete domain of the RNA polymerase PA gene. The four rescued viruses exhibited a temperature-sensitive phenotype that we found was associated with a defect in the transport of the PA–PB1 dimer to the nucleus, where viral replication occurs. Thesetsdeletion mutants were shown to be attenuated and to be able to produce antibodies in mice and to protect them from a lethal challenge. Assays to select revertants that were able to grow efficiently at a restrictive temperature failed, showing that these deletion mutants are genetically more stable than conventional substitution mutants. These results are of interest for the design of genetically stable live influenza virus vaccines.

scholarly journals A temperature-sensitive mutation of the Schizosaccharomyces pombe gene nuc2+ that encodes a nuclear scaffold-like protein blocks spindle elongation in mitotic anaphase.

1988 ◽  
Vol 106 (4) ◽  
pp. 1171-1183 ◽  
Author(s):  
T Hirano ◽  
Y Hiraoka ◽  
M Yanagida
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Gradient Centrifugation ◽  
Metaphase Plate ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Permissive Temperature ◽  
Wild Type ◽  
In The Wild ◽  
Spindle Elongation ◽  
Mutant Cells

A temperature-sensitive mutant nuc2-663 of the fission yeast Schizosaccharomyces pombe specifically blocks mitotic spindle elongation at restrictive temperature so that nuclei in arrested cells contain a short uniform spindle (approximately 3-micron long), which runs through a metaphase plate-like structure consisting of three condensed chromosomes. In the wild-type or in the mutant cells at permissive temperature, the spindle is fully extended approximately 15-micron long in anaphase. The nuc2' gene was cloned in a 2.4-kb genomic DNA fragment by transformation, and its complete nucleotide sequence was determined. Its coding region predicts a 665-residues internally repeating protein (76.250 mol wt). By immunoblots using anti-sera raised against lacZ-nuc2+ fused proteins, a polypeptide (designated p67; 67,000 mol wt) encoded by nuc2+ is detected in the wild-type S. pombe extracts; the amount of p67 is greatly increased when multi-copy or high-expression plasmids carrying the nuc2+ gene are introduced into the S. pombe cells. Cellular fractionation and Percoll gradient centrifugation combined with immunoblotting show that p67 cofractionates with nuclei and is enriched in resistant structure that is insoluble in 2 M NaCl, 25 mM lithium 3,5'-diiodosalicylate, and 1% Triton but is soluble in 8 M urea. In nuc2 mutant cells, however, soluble p76, perhaps an unprocessed precursor, accumulates in addition to insoluble p67. The role of nuc2+ gene may be to interconnect nuclear and cytoskeletal functions in chromosome separation.

scholarly journals Mutants of Saccharomyces cerevisiae unresponsive to cell division control by polypeptide mating hormone.

1980 ◽  
Vol 85 (3) ◽  
pp. 811-822 ◽  
Author(s):  
L H Hartwell
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Types ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Alpha Cells ◽  
Wild Type ◽  
Cell Type ◽  
Mating Test ◽  
Alpha Factor ◽  
Cell Division Control

Temperature-sensitive mutations that produce insensitivity to division arrest by alpha-factor, a mating pheromone, were isolated in an MATa strain of Saccharomyces cerevisiae and shown by complementation studies to difine eight genes. All of these mutations (designated ste) produce sterility at the restrictive temperature in MATa cells, and mutations in seven of the genes produce sterility in MAT alpha cells. In no case was the sterility associated with these mutations coorectible by including wild-type cells of the same mating type in the mating test nor did nay of the mutants inhibit mating of the wild-type cells; the defect appears to be intrinsic to the cell for mutations in each of the genes. Apparently, none of the mutants is defective exclusively in division arrest by alpha-factor, as the sterility of none is suppressed by a temperature-sensitive cdc 28 mutation (the latter imposes division arrest at the correct cell cycle stage for mating). The mutants were examined for features that are inducible in MATa cells by alpha-factor (agglutinin synthesis as well as division arrest) and for the characteristics that constitutively distinguish MATa from MAT alpha cells (a-factor production, alpha-factor destruction). ste2 Mutants are defective specifically in the two inducible properties, whereas ste4, 5, 7, 8, 9, 11, and 12 mutants are defective, to varying degrees, in constitutive as well as inducible aspects. Mutations in ste8 and 9 assume a polar budding pattern unlike either MATa or MAT alpha cells but characteristic of MATa/alpha cells. This study defines seven genes that function in two cell types (MATa and alpha) to control the differentiation of cell type and one gene, ste2, that functions exclusively in MATa cells to mediate responsiveness to polypeptide hormone.

scholarly journals Acidification of endosome subpopulations in wild-type Chinese hamster ovary cells and temperature-sensitive acidification-defective mutants.

1989 ◽  
Vol 108 (4) ◽  
pp. 1291-1300 ◽  
Author(s):  
S Schmid ◽  
R Fuchs ◽  
M Kielian ◽  
A Helenius ◽  
I Mellman
Keyword(s):  
Chinese Hamster Ovary ◽  
Cho Cells ◽  
Chinese Hamster ◽  
Temperature Sensitive ◽  
Cell Fractionation ◽  
Permissive Temperature ◽  
Wild Type ◽  
Late Endosomes ◽  
Early Endosomes

During endocytosis in Chinese hamster ovary (CHO) cells, Semliki Forest virus (SFV) passes through two distinct subpopulations of endosomes before reaching lysosomes. One subpopulation, defined by cell fractionation using free flow electrophoresis as "early endosomes," constitutes the major site of membrane and receptor recycling; while "late endosomes," an electrophoretically distinct endosome subpopulation, are involved in the delivery of endosomal content to lysosomes. In this paper, the pH-sensitive conformational changes of the SFV E1 spike glycoprotein were used to study the acidification of these defined endosome subpopulations in intact wild-type and acidification-defective CHO cells. Different virus strains were used to measure the kinetics at which internalized SFV was delivered to endosomes of pH less than or equal to 6.2 (the pH at which wild-type E1 becomes resistant to trypsin digestion) vs. endosomes of pH less than or equal to 5.3 (the threshold pH for E1 of the SFV mutant fus-1). By correlating the kinetics of acquisition of E1 trypsin resistance with the transfer of SFV among distinct endosome subpopulations defined by cell fractionation, we found that after a brief residence in vesicles of relatively neutral pH, internalized virus encountered pH less than or equal to 6.2 in early endosomes with a t1/2 of 5 min. Although a fraction of the virus reached a pH of less than or equal to 5.3 in early endosomes, most fus-1 SFV did not exhibit the acid-induced conformational change until arrival in late endosomes (t1/2 = 8-10 min). Thus, acidification of both endosome subpopulations was heterogeneous. However, passage of SFV through a less acidic early endosome subpopulation always preceded arrival in the more acidic late endosome subpopulation. In mutant CHO cells with temperature-sensitive defects in endosome acidification in vitro, acidification of both early and late endosomes was found to be impaired at the restrictive temperature (41 degrees C). The acidification defect was also found to be partially penetrant at the permissive temperature, resulting in the inability of any early endosomes in these cells to attain pH less than or equal to 5.3. In vitro studies of endosomes isolated from mutant cells suggested that the acidification defect is most likely in the proton pump itself. In one mutant, this defect resulted in increased sensitivity of the electrogenic H+ pump to fluctuations in the endosomal membrane potential.

scholarly journals PRP18, a protein required for the second reaction in pre-mRNA splicing.

1990 ◽  
Vol 10 (1) ◽  
pp. 324-332 ◽  
Author(s):  
U Vijayraghavan ◽  
J Abelson
Keyword(s):  
Micrococcal Nuclease ◽  
Heat Inactivation ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Wild Type ◽  
Exon 1 ◽  
In Vitro Splicing

We have investigated the role of a novel temperature-sensitive splicing mutation, prp18. We had previously demonstrated that an accumulation of the lariat intermediate of splicing occurred at the restrictive temperature in vivo. We have now used the yeast in vitro splicing system to show that extracts from this mutant strain are heat labile for the second reaction of splicing. The heat inactivation of prp18 extracts results from loss of activity of an exchangeable component. Inactivated prp18 extracts are complemented by heat-inactivated extracts from other mutants or by fractions from wild-type extracts. In heat-inactivated prp18 extracts, 40S splicing complexes containing lariat intermediate and exon 1 can assemble. The intermediates in this 40S complex can be chased to products by complementing extracts in the presence of ATP. Both complementation of extracts and chasing of the isolated prp18 spliceosomes takes place with micrococcal nuclease-treated extracts. Furthermore, the complementation profile with fractions of wild-type extracts indicates that the splicing defect results from a mutation in a previously designated factor required for the second step of splicing. The isolation of this mutant as temperature-sensitive lethal has also facilitated cloning of the wild-type allele by complementation.

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