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N S Petersen

Publications and source records attributed to N S Petersen.

At least 19 recordsLinked to original sources
PubMed2001

Expression of the 53 kD forked protein rescues F-actin bundle formation and mutant bristle phenotypes in Drosophila.

forked mutations affect bristle development in Drosophila pupae, resulting in short, thick, gnarled bristles in the adult. The forked proteins are components of 200-300-microm-long actin fiber bundles that are present transiently during pupal development [Petersen et al., 1994: Genetics 136:173-182]. These bundles are composed of segments of 3-10 microm long, and forked protein is localized along the actin fiber bundle segments and accumulates at the junctions connecting them longitudinally. In the forked mutants, f(36a) and f(hd), F-actin bundles are greatly reduced in number and size, and bundle segmentation is absent. The p-element, P[w(+), falter] contains a 5.3-kb fragment of the forked gene that encodes the 53-kD forked protein [Lankenau et al., 1996: Mol Cell Biol 16:3535-3544]. Expression of only the 53-kD forked protein is sufficient to rescue the actin bundle and bristle phenotypes of f(36a) and f(hd) mutant flies. The 5.3-kb forked sequence, although smaller than the 13-kb region previously shown to rescue forked mutants [Petersen et al., 1994: Genetics 136:173-182], does contain the core forked sequence that encodes actin binding and bundling domains in cultured mammalian cells [Grieshaber and Petersen, 1999: J Cell Sci 112:2203-2211]. These data show that the 53-kD forked protein is sufficient for normal bristle development and that the domains shown previously to be important for actin bundling in cell culture may be all that are required for normal actin bundle formation in developing Drosophila bristles.

Actins↗
PubMed1999

The Drosophila forked protein induces the formation of actin fiber bundles in vertebrate cells.

The forked protein is an actin binding protein involved in the formation of large actin fiber bundles in developing Drosophila bristles. These are the largest example of a type of actin bundle characterized by parallel, hexagonally packed actin fibers, also found in intestinal microvilli, kidney proximal tubule microvilli, and stereocilia in the ear. Understanding how these structures are constructed and how that construction is regulated is an important question in cell and developmental biology. Because the timing of forked gene expression coincides with the formation of the actin fiber bundles, and since the forked protein is localized at the site of initiation of these bundles before they form, it has been proposed that the forked protein is an initiator of actin bundle formation. In this paper we show that the forked protein can induce the formation of bundles and increase actin polymerization in vertebrate cells. We use this system to identify regions of the forked protein which are essential for bundle formation and actin co-localization.

Actins↗
PubMed1998

Changes in the F-actin cytoskeleton during neurosensory bristle development in Drosophila: the role of singed and forked proteins.

Drosophila neurosensory bristle development provides an excellent model system to study the role of the actin-based cytoskeleton in polarized cell growth. We used confocal fluorescence microscopy of isolated thoracic tissue to characterize changes in F-actin that occurred during macrochaete development in wild type flies and mutants that have aberrant bristle morphology. At the earliest stages in wild type bristle development, cortical patches of F-actin were present, but no bundles were observed. Actin bundles began to form at 31% of pupal development and became more prominent as development progressed. The F-actin patches gradually disappeared and were no longer present by 38% of pupal development. The distribution of F-actin in singed3 mutant macrochaetae was indistinguishable from wild type bristles until 35% of development when the actin bundles began to splay and appear ribbon-like. In forked36a bristles, the mutant phenotype was evident at earlier stages of development than the singed3 mutant. Wild type tissue stained with antibodies against the forked protein demonstrated that the forked protein colocalized with F-actin structures found in early and late stage developing macrochaetae. Antibodies against the singed protein showed it appeared to localize with F-actin structures only at later stages in development. These data suggested that the forked gene product was required for the initiation of fiber bundle formation and the singed gene product was required for the maintenance of fiber bundle morphology during bristle development. Similar analyses of singed3/forked36a double mutants provided additional genetic evidence that the forked gene product was required before the singed gene product. Further, the analyses suggested that at least one additional crosslinking protein was present in these bundles.

Actins↗
PubMed1997

Induction of the heat shock response and translational thermotolerance in day 15 ovine trophectoderm.

The objectives of this study were to determine the ability of trophectoderm from preimplantation ovine embryos to synthesize hsp70 in response to heat shock and to identify conditions which induce translational thermotolerance in this tissue. Day 15 embryos were collected, and proteins synthesized in 1.5-mm sections of trophectoderm were radioactively labeled with (35)S-methionine. One-dimensional SDS-PAGE gels, two-dimensional gel electrophoresis and Western blots were utilized to characterize the heat shock response and to examine the induction of translational thermotolerance. Increased synthesis of the 70 kDa heat shock proteins and a protein with an approximate molecular weight of 15 to 20 kDa was observed with heat shock (> or = 42 degrees C). Total protein synthesis decreased (P < 0.05) with increased intensity of heat shock. At 45 degrees C, protein synthesis was suppressed with little or no synthesis of all proteins including hsp70. Recovery of protein synthesis following a severe heat shock (45 degrees C for 20 min) occurred faster (P < 0.05) in trophectoderm pretreated with a mild heat shock (42 degrees C for 30 min) than trophectoderm not pretreated with mild heat. In summary, trophoblastic tissue obtained from ovine embryos exhibit the characteristic "heatshock" response similar to that described for other mammalian systems. In addition, a sublethal heat shock induced the ability of the tissue to resume protein synthesis following severe heat stress. Since maintaining protein synthesis is crucial to embryonic survival, manipulation of the heat-shock response may provide a method to enhance embryonic survival.

Journal Article↗
PubMed1994

forked proteins are components of fiber bundles present in developing bristles of Drosophila melanogaster.

The forked (f) gene of Drosophila melanogaster encodes six different transcripts 6.4, 5.6, 5.4, 2.5, 1.9, and 1.1 kb long. These transcripts arise by the use of alternative promoters. A polyclonal antibody raised against a domain common to all of the forked-encoded products has been used to identify forked proteins on two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels and in Drosophila pupal tissues. The antibody stains fiber bundles present in bristle cells for about 15 hr during normal pupal development. Electron microscopy shows that these fibers are present from 40 to 53 hr in bristles of wild-type flies but are absent in the null f36a mutant. The forked protein(s) thus appear to be an essential part of the bristle fibers. The phenotype of the f36a mutation can be rescued by a 13-kb fragment of the forked locus containing the coding regions for the 2.5, 1.9, and 1.1-kb transcripts, suggesting that the proteins encoded by the three large forked RNAs are dispensable during bristle development. Increasing the copy number of a P[w+,f+] construct containing the 13-kb fragment induces a hypermorphic bristle phenotype whose severity correlates with the number of copies of P[w+,f+] present. These results indicate that alterations in the ratios among the forked proteins, or between forked products and other components of the fiber, result in abnormal assembly of the fibrillar cytoplasmic structures necessary for bristle morphogenesis.

Animals↗
PubMed1990

Heat shock induces a decrease in incorporation of 8-azidoadenosine 5'-triphosphate into a 42 kilodalton protein in Drosophila salivary glands.

The ATP photoaffinity analogue 8-azidoadenosine 5'-triphosphate (8N3ATP) was used to identify changes which occur in ATP binding proteins in Drosophila salivary glands following heat shock. Photolabeling experiments were done on salivary gland homogenates. Photoincorporation of 8N3ATP was observed in several proteins in both 25 degrees C control and 35 degrees C heat-shocked samples. A 42 kDa protein showed a decrease in the level of photoincorporation observed at saturation with the analogue following heat shock. A 2 min heat shock is enough to induce the effect. Protection against photolabeling was observed with low concentrations (5 microM) of ATP, while excess GTP did not protect, demonstrating that the nucleotide binding site is specific for ATP. The change is rapid enough to suggest that it is one of the earliest cellular changes in response to heat shock.

Adenosine Triphosphate↗
PubMed1990

Stages of cell hair construction in Drosophila.

The construction of cell hairs (trichomes) on the wings of Drosophila occurs in synchrony on 30,000 cells over a period of about 20 hr. Changes in both morphology and patterns of protein synthesis occur rapidly during this time period. In this report we describe the use of stress-induced (heat shock) abnormalities in morphogenesis to provide further details on the stepwise processes of differentiation within single wing cells. A cartoon summary of the overall process and a discussion of some possible mechanisms is included.

Animals↗
PubMed1990

Heat shock causes the collapse of the intermediate filament cytoskeleton in Drosophila embryos.

Heat shock has a dramatic effect on the organization of the cytoplasm, causing the intermediate filament cytoskeleton to aggregate at the nucleus. This has previously been shown in cultured Drosophila and mammalian cells. In this paper we analyze the heat lability of the intermediate filament cytoskeleton in early Drosophila embryos by indirect immunofluorescence. At all stages of embryogenesis tested, the intermediate filament cytoskeleton, which is maternally provided, is severely disturbed by 30 min heat shock at 37 degrees C. After the nuclei have migrated to the subcortical cytoplasm, it collapses around them. Nuclei in all heat-shocked embryos are considerably enlarged and become displaced. Embryos before cellular blastoderm stage, in which heat shock protein synthesis is not inducible, are irreversibly arrested in development by heat shock. Embryos at or after cellular blastoderm, which do synthesize heat shock proteins in response to stress, are also immediately arrested in development but continue development when returned to 25 degrees C. We discuss the possibility that cytoplasmic events such as the intermediate filament cytoskeleton rearrangement may be involved in heat shock-mediated phenocopy induction.

Animals↗
PubMed1990

Effects of heat and chemical stress on development.

Similarities in the means by which developmental defects are induced in vertebrates and Drosophila suggest that some kinds of defects may be induced by similar mechanisms. The similarities include the fact that heat and a group of chemicals that induce synthesis of heat-shock proteins induce defects in mammals, chickens, and flies. Different kinds of defects are even produced in one type of animal, depending on the precise timing of the environmental insult. The effectiveness of the environmental treatment in inducing defects depends on the genetic background of the animal as well as on past exposure to chemicals and heat. Developmental defects induced by heat in mice, rats, and flies can all be prevented by thermotolerance-inducing treatments. The basis for these effects has been studied at the molecular level in Drosophila, and the evidence indicates that these teratogens and the thermotolerance-inducing treatments affect the level or timing of expression of specific genes during critical periods in the developmental program.

Abnormalities, Drug-Induced↗
PubMed1989

Effects of heat shock on protein processing and turnover in developing Drosophila wings.

Developmental defects called phenocopies can be induced by heating Drosophila melanogaster pupae at specific developmental stages. The induction of the defects is thought to be a result of interference with gene expression at some level (Petersen and Mitchell, Dev Biol 1987; 121:335-341, 1987). Here we look at protein turnover in developing 52-hour wings and at the effect of heat on the proteolytic processing of three proteins that normally turn over rapidly. The effect of the heat treatment itself on the turnover of each protein is different. However, all of the proteins appear to be stabilized at 25 degrees C during recovery from severe heat shocks.

Animals↗
PubMed1989

Epithelial differentiation in Drosophila pupae.

The construction of cell hairs on the wings in developing pupae of Drosophila provides a unique system for studies of the regulation of differentiation in the absence of cell division. Early steps in hair construction are the extrusion of cell hairs and the deposition of the external impervious layer called "cuticulin." Some properties of six of the most abundant proteins that are present during the early stages of hair construction are described. These proteins make up about 40% of the total protein of the preparation.

Animals↗
PubMed1989

Thermotolerance is developmentally dependent in germinating wheat seed.

During the initial 9 to 12 hours of imbibition, the imbibing wheat (Triticum aestivum L.) seed was found to exhibit substantial tolerance to high temperature relative to later times of imbibition. Tolerance was assessed by seed viability and seedling growth. This initial high temperature tolerance gradually declines with increasing time of seed imbibition. A range of 2 hour heat pretreatments (38-42 degrees C) prior to imposition of a 2 hour heat shock (51-53 degrees C) during this same 9 to 12 hour interval was unable to increase survival or seedling growth over that of seed that did not receive a pretreatment. However, after 9 to 12 hours of imbibition the pretreatment provided both increased survival and increased seedling growth, measured 120 hours later, i.e., classical thermotolerance could be acquired. This response is called a ;thermotolerance transition.' Isolated embryos responded in a similar manner using a 2,3,5-triphenyltetrazolium chloride assay for viability determination following heat treatments. The high temperature tolerance during early imbibition indicates that the thermotolerance transition involves the loss of an existing thermotolerance coincident with acquiring the ability to become thermotolerant following heat pretreatment. Despite the inability to acquire thermotolerance, heat shock protein synthesis was induced by heat shock immediately upon imbibition of wheat seed or isolated embryos. Developmentally regulated heat shock proteins of 58 to 60, 46, 40, and 14 kilodaltons were detected at 1.5 hours of imbibition following heat shock, but were absent or greatly reduced by 12 hours. Constitutive synthesis of 70 and 90 kilodalton hsp groups appeared to be greater at 1.5 hours of imbibition than at 12 hours of imbibition.

Journal Article↗
PubMed1989

Heat shock response of germinating embryos of wheat : effects of imbibition time and seed vigor.

Seeds frequently face a hostile environment during early germination. In order to determine whether seeds have evolved unique mechanisms to deal with such environments, a survey of the heat shock response in isolated embryos of wheat (Triticum aestivum L.) was undertaken. Embryos simultaneously heat shocked and labeled following several different periods of prior imbibition up to 12 hours synthesized many groups of heat shock proteins (hsps) typical of other plant and animal systems. Also, five developmentally dependent hsps, present only in treatments imbibed less than 6 hours prior to heat shock, were detected. These proteins have relative molecular masses of 14, 40, 46, 58, and 60 kilodaltons. One of the developmentally dependent hsps is among the most highly labeled hsps found in early imbibed embryos. The possibility that this protein is the E(m) protein is discussed. The hypothesis that the capacity for hsp synthesis is affected by seed vigor was also tested. The heat shock responses of embryos from two high and two low vigor seed lots were compared using one- and two-dimensional electrophoresis of labelled protein extracts. The results indicate that both of the low vigor lots tested had weaker heat shock responses than their high vigor counterparts overall. Not all hsps were relatively less abundant in low vigor embryos. The developmentally dependent hsps showed little relationship to vigor. Some of the developmentally dependent hsps were actually made in greater amounts, relative to other proteins, in the low vigor seed lots. The results presented here demonstrate that imbibing embryos are capable of expressing an enhanced heat shock response, and that this response is related to seed vigor.

Journal Article↗
PubMed1988

Heat shock protection against cold stress of Drosophila melanogaster.

Heat shock protein synthesis can be induced during recovery from cold treatment of Drosophila melanogaster larvae. Survival of larvae after a cold treatment is dramatically improved by a mild heat shock just before the cold shock. The conditions which induce tolerance to cold are similar to those which confer tolerance to heat.

Acclimatization↗
PubMed1987

Spontaneous fragmentation of several proteins in Drosophila pupae.

Autoproteolysis is an essential activity in the expression of the entire genomes of a number of viruses. That is, new viruses can be produced only after large polyprotein products translated from the genome or from subgenomic mRNA degrade themselves to the polypeptides necessary for RNA replication or for the construction of new virus particles. We have recently shown that the major heat shock protein of Drosophila and a mouse cell line (70 kDa) also undergoes autoproteolysis with the production of specific patterns of smaller polypeptides. We show now that many other proteins in eucaryotic tissues also have a potential for self-degradation. We suggest that special coding regions in many genes may have important roles in both protein turnover and in the production of regulatory peptides.

Animals↗
PubMed1987

The induction of a multiple wing hair phenocopy by heat shock in mutant heterozygotes.

Phenocopies are developmental defects induced by environmental treatments during differentiation. Because of their resemblance to mutant phenotypes it has been suggested that phenocopies are due to environmental effects on the expression of specific genes during development. In this paper we describe the heat shock (40.8 degrees C) induction of a multiple wing hair phenocopy in the mutant heterozygote (mwh/+). The mwh phenocopy is only induced in heterozygotes of the recessive mutant during a short sensitive period which appears to be the time of expression of the multiple wing hair gene. We suggest that this phenocopy is due to failure of mwh gene expression and that phenocopy sensitive periods may be useful in identifying expression periods for particular genes during development. Furthermore we have been able to demonstrate that a 35 degrees C pretreatment will prevent the induction of the multiple wing hair phenocopy. A similar 35 degrees C pretreatment prevents induction of several different phenocopies by heat in wild-type flies (N. S. Petersen and H. K. Mitchell (1985). In "Comprehensive Insect Physiology, Biochemistry and Pharmacology, Vol. X, Biochemistry." Pergamon, New York). This indicates a common molecular mechanism for both the induction and the prevention of heat-induced phenocopies.

Animals↗