Unknown,Transcriptomics,Genomics,Proteomics

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Starvation response in Drosophila and its implication for sex specific metabolism and aging

ABSTRACT: Background All animals must be able to adapt to changes in nutrient quality and supply. One striking aspect of this adaptive response is the extension of lifespan when caloric intake is reduced. These animals are also more resistant to various stresses, including starvation. We have characterized the response of adult Drosophila males and females to starvation and sugar conditions using high density microarrays. Results We have organized the regulated genes into specific metabolic and physiologic pathways. Most of the highly regulated genes have a strong sex bias. In addition to expected sex specific changes, such as egg production in females, we found unexpected biases in sensory systems, amino acid and purine metabolism, and signaling pathways. Comparison of starvation to caloric restriction revealed numerous overlaps. Conclusions Our results support the notion that starvation response shares similarities to caloric restriction. They have relevance for sex specific differences in longevity and in response to nutrient conditions which alter lifespan. Nutrient Conditions and Fly handling Larvae were kept on apple juice agar plates with yeast, and the larvae were raised at 25Â°C. For the developmental control larvae were collected 39-41 h AEL, for the developmental time-points at 51-53 hours and every 12 hours until 99-101 hours. Adult flies were kept at 25Â°C in 50 ml PS-tubes flat bottom (Greiner bio-one, Frickenhausen, Germany) on standard fly food (16.5 g yeast, 81,5 g cornmeal, 8 g agar, 100 ml sugar beet sirup and 200 ml 10% Nipagin in EtOH). Flies were collected that had hatched in 24 hours and kept in groups of ~200 flies/tube. After 5 days we separated males and females and put them in groups of 80/28 ml PS-tube. We allowed for one day CO2 recovery on standard fly food before flies were moved to 1) tubes with yeast paste on PBS soaked filter paper (control) 2) tubes with only PBS soaked filter paper (starvation) or 3) tubes with filter paper soaked in PBS with 20% Sucrose (sugar). After 24 or 48 hours flies were shock frozen in liquid nitrogen and stored at - 80Â°C for further handling. Males and females were assayed separately. For females, we performed 24 and 48 starvation, and 24 and 48 hours sugar. For the males only 24 hour starvation was done, since most died upon 48 hour starvation; and 24 and 48 hour sugar. Briefly, flies were collected within a 24 hour period, allowed to stay together for 4 days, separated into males and females, and allowed one day recovery in normal fly food. Afterwards, the flies were placed into three conditions: fresh yeast plus PBS, PBS or PBS plus 20 % sucrose. These experiments essentially parallel the experimental set up of previous larval experiments (7). The starvation and PBS were then compared with yeast (control).

ORGANISM(S): Drosophila melanogaster

SUBMITTER: Matthias Bauer

PROVIDER: E-GEOD-1672 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Purine and folate metabolism as a potential target of sex-specific nutrient allocation in Drosophila and its implication for lifespan-reproduction tradeoff.

Bauer Matthias M Katzenberger Jörg D JD Hamm Anne C AC Bonaus Melanie M Zinke Ingo I Jaekel Jens J Pankratz Michael J MJ

Physiological genomics 20060328 3

The reallocation of metabolic resources is important for survival during periods of limited nutrient intake. This has an influence on diverse physiological processes, including reproduction, repair, and aging. One important aspect of resource allocation is the difference between males and females in response to nutrient stress. We identified several groups of genes that are regulated in a sex-biased manner under complete or protein starvation. These range from expected differences in genes invol ...[more]

PMID: 16569777

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Project description:Mice used in this study were 129/sv males, 8-15 weeks of age, which were housed individually and received water ad libitum. Normal fed animals were fed before and during the 48h experiment with standard food ad libitum. Sugar fed animals were fed before the experiment with standard food ad libitum and during the 48h experiment with 50% (w/v) sugar solution (40% glucose, 10% sucrose). Mice were killed by CO2 asphyxiation. The livers were snap-frozen in liquid nitrogen and stored at -80 degrees C. Total RNA was prepared using the Nucleospin RNA L kit (Macherey-Nagel, Düren, Germany), with an additional step in which the final eluate was used for a subsequent elution step. PolyA RNA was extracted with the Ambion (Ambion Inc, Austin, USA) Purist kit according to the manufacturer's protocols. Equal amounts of polyA RNA were pooled to generate pools of all animals. Pool1, normal = 3 animals (N1, N2, N3), pool2, normal = 3 animals (N4, N5, N6), pool3, = 4 animals (N7, N8, N9, N10), pool1, sugar = 3 animals (Su1, Su2, Su3), pool2, sugar = 3 animals (Su4, Su5, Su6), pool3, sugar = 4 animals (Su7, Su8, Su9, Su10). Labeled cDNA was synthesized from 1.5 µg polyA RNA using the Amersham (Amersham Europe, Freiburg, Germany) direct cDNA labeling kit. Removal of the unincorporated dyes and concentration of the target were done with Microcon 30 (Millipore, Bedford, MA) spin columns according to the manufacturer's instructions. The concentrated probes were hybridized to the microarray in 1x dig easy hyb buffer (Hoffman-la Roche, Basel, CH) overnight at 42 degrees C. After hybridization the microarrays are washed 5’ in 2x SSC, 0.1% SDS at 42 degrees C; 10’ in 0.1x SSC, 0.1% SDS at RT; 4 times 1’ in 0.1x SSC at RT and shortly dipped into 0.01x SSC. Drying is performed in centrifuge on a microtiterplate holder at 130 rcf for 7’. Slides are stored in dark until they are scanned. Arrays were scanned using the dual laser scanner Axon 4000B and the corresponding software Genepix 4 (Axon Inc., Union City, CA, USA). Both channels (532 nm for Cy3 and 635 nm Cy5) were scanned in parallel and stored as 16 bit tiff files. The absolute intensity values span the range from 0 to 65,535. The scans were performed with a resolution of 10 µm. From each spot with a mean diameter of 100 µm, 100 data pixels were recorded. Individual local background area around the spots were defined, which included approximately 400 pixels and excludes neighboring spots. For each channel, the raw data was calculated as the median intensity of all foreground pixels with respect to all background pixels. Each array was scanned three times (low, medium and high scan) with different signal amplification factors (voltage settings of the photo multiplier tubes), but with the same laser power. The channels for Cy3 and Cy5 were balanced in each scan for approximately the same intensity profile. In the low scan no spot was saturated, in the high scan the signal amplification for Cy5 was set to approximately 80% of maximum and the Cy3 amplification was adjusted to this. The settings used in the medium scan lie between the low and the high scan. This method for scanning has several advantages. In the low scan where no spot is in saturation, it is possible to calculate the real ratio for genes with high expression levels; however, those with a low expression level are most likely not recognized. In order not to lose these a high scan is made; in this case the information on the saturated spots is lost so the two scans complement each other. The medium scan produces additional values for subsequent calculations. By scanning the arrays three times errors which occur while recording and which might increase the error factor in the normalization are averaged. The data processing was automated in a Visual Basic/Excel (Microsoft) program, which integrates the following steps. Raw data are derived from the result files generated by scanning and picture analysis software Genepix. The spot diameter is to lie in the range from 80 to 120 µm otherwise these spots are not included in analysis. From the pixel to pixel ratios between the foreground values of both colors, the standard deviation (SD) is calculated. Those spots which show a ratio SD of higher than 3 are excluded from analysis due to inconsistency. The foreground signal of each spot is corrected by subtracting the corresponding local background. Resulting values which are lower than the background are replaced by the background value. This defines the minimum measurement threshold as the background and avoids calculations of completely wrong ratios, e.g., if the background corrected value for one channel is close to zero. Spots are marked as saturated in one channel if more than 10% of the foreground pixels are at the highest absolute value. From the unsaturated data points of all three scans, linear regression between the low and medium, and between low and high scans, are calculated for both colors. Taking these regressions, the values of saturated spots are replaced by estimated ones which reflect the real intensity. The generated data set of each scan is normalized afterwards based on the intensity-dependent methods as described by Yang et al (Yang YH, Dudoit S, Luu P, Lin DM, Peng V, Ngai J, and Speed TP. Normalization for cDNA microarray data: robust composite method addressing single and multiple slide systematic variation. Nucleic Acids Res. 30: e15, 2002). The ratios are calculated as log2 transformed values: M=log2 (Cy5/Cy3). Number describing the spot intensity A=log2sqrt (Cy5*Cy3) is calculated according to Yang et al. A within pin-tip group loess fit to the MA-plot was made. The loess scatter plot smoother performs robust locally fits using a tricube function to weight the values relative to the median point in the intensity interval. As interval size 20% was chosen, which corresponds to 180 data points in a pin-tip group containing 30 by 30 spots. After combining the normalized data from all blocks the data sets of all scans are additionally normalized using a global approach. The normalization was performed so that the sum of all log transformed ratios (M) is 0. All statistical normalizations are based on the assumption that (1) the majority of genes are not changed in their expression and (2) that the overall up and down regulations statistically compensate each other in sum. Taking this into account, the standard deviation in the ratios of the stable genes (80% of the most unchanged genes) could be seen as the measurement noise of the array experiments. To be able to compare the different scans and different normalized microarrays, the SD of the stable genes ratios was adjusted to a medium estimated value of 0.2, which is dependent on the used array system. This value does not influence the subsequent statistical analysis because the normal distribution of the data is not changed. For each microarray the normalized and adjusted log ratios of the three scans are averaged. Keywords = microarray analysis Keywords = nutrient response Keywords = caloric restriction Keywords = metabolic signaling Keywords = aging/longevity This SuperSeries is composed of the following subset Series: GSE851: liver, 48h sugar GSE852: liver, 48h starved GSE853: liver, 24h starved Refer to individual Series

Project description:Background Insulin signaling pathway is conserved from worms to humans. In Drosophila, three insulin-like peptides (dilps) are expressed in the insulin producing cells (IPCs) in the brain. In order to identify target genes of insulin signaling, the IPCs of female flies were destroyed during development by expressing apoptosis inducing factors reaper and head involution defective under control of the promoter region of dilp3. These insulin-deficient flies were analysed using high density microarrays. Results From the genes that appeared to be regulated in the absence of IPCs, the strongest difference was found for a gene involved in carbohydrate metabolism. Sequence analysis revealed that it is an alpha-glucosidase, which is able to break down disaccharides and/or glycogen. Conclusions We could identify an alpha-glucosidase, involved in carbohydrate metabolism, to be strongly affected in the context of decreased insulin signaling. The striking feature of this regulation was not only that it was the highest regulated, but it was the only gene regulated to this degree. Nutrient Conditions and Fly handling Experimental and control female flies were collected after hatching, then kept on fly maintenance food and separated from males after 11 days. After one day of recovery from carbon dioxide treatment, females were put in cages with PBS agar plates and supplied with yeast paste as only food source for 48 hours. Flies were shock frozen in liquid nitrogen and stored at - 80Â°C for further handling. Keywords: IPC knockout, 14 day old female flies, 48h yeast feeding Insulin producing cell deficient flies were compared to control flies. Two independent biological repeats were performed. From the two repeats, 5 chips were hybridised, including dye swap Experimental and control female flies were collected after hatching, then kept on fly maintenance food and separated from males after 11 days. After one day of recovery from carbon dioxide treatment, females were put in cages with PBS agar plates and supplied with yeast paste as only food source for 48 hours. The microarray was scanned 3 times: low scan (suffix _L in data table) with a low amplification / intensity to avoid saturated spots for proper data analysis, high scan (suffix _H in data table) with a high amplification / intensity to detect also weak fluorescent spots which are missed in the low scan and medium scan which lies between high and low intensity and gives additional data points for subsequent calculations. Both copies and all hybridisation repeats were used for normalisation, VALUE therefore has the same value for these copies in all relevant hybridisations. For additional information see publication and web link. Keywords = insulin, aging, longevity, nutrient dependance Lot batch = FP7

Project description:(This section will be revisited in good time prior to publication, for final approval) Research within the field of functional genomics provides a more profound understanding of living organisms, by elucidating the interaction between genes and gene products. This is of increasing importance in many fields, and especially within cancer research. With the use of microarray technology, the gene expression of a vast number of genes can be measured simultaneously. This allows us insight into tumor biology, and an opportunity to obtain knowledge of diagnostic and prognostic value, as well as hints towards the causes of cancer. In this study the gene expression in a selection of human neuroendocrine (NE) and non-neuroendocrine tumor cell lines were compared. Both qualitative and quantitative methods were applied to get an insight into the NE tumor biology. NE cells are found in practically every organ and tissue in the body and are assigned to synthesize peptide hormones and take up amino acids and transform these into biogenic amines by carboxylation. NE tumors arise after malignant transformation of neuroendocrine cells and are usually highly differentiated and have a low growth rate, which makes this a high prevalence tumor type. These rather rare tumors characteristically express NE markers, such as chromogranin A, and contains characteristic dense-secretory core granules. By using cDNA microarray analysis, the gene expression profiles of various NE tumor cell lines (e. g. carcinoid, neuroblastoma, medullary thyroid carcinoma and endocrine pancreatic tumor) were compared with those of non-NE tumor cells. As a reference the commercially available Universal human RNA reference (Stratagene) was used. Verification of the results were done by real time RT-PCR analysis after the NE nature of the cell lines was stated by immunohistochemical, electron microscopic and light microscopic examinations. A large number of genes were differentially expressed in NE cell lines vs. the non-NE cell lines, and were found to be of interest in NE tumor biology. Some of these genes were previously known in NE tumor biology, whereas the vast majority of the specified genes are novel in the context of NE tumor biology. Genes with little previous information were also identified and thought to be an asset in the search of new NE markers. A feasible prospective of the study would be expansion with additional samples cell lines and a more thorough verification with real time RT-PCR analysis. This would enhance the credibility and thus the utility of the findings. Future studies on the biological functions of the candidate genes and the mechanisms of their regulation, will hopefully enable suggestions of new NE markers of prognostic or diagnostic value, and eventually new drug targets. Keywords: neuroendocrine, neuroendocrine markers, gene expression profiling, cDNA microarray The hybridisation was performed by an experienced laboratory technician Eli Helge, (Dept. of Laboratory Medicine, Children`s and Women`s health, NTNU) at the microarray core facility. Three separate runs with 10, 11 and 3 slides was needed to obtain the 20 hybridisations (dyeswap x 10 cell lines) planned for this study. Of the 10 cell lines 6 were neuroendocrine and 4 were non-neuroendocrine. For comparison between these two groups the universal human reference RNA (Stratagene) was used as the "control" on each slide. An adapted version of the 3DNA Array 350 protocol (Genisphere) was used. The slides were scanned with a ScanArrayTMExpressHT (Packard BioScience) twice immediately after the hybridisation was completed to avoid photo bleaching of the fluorescent dyes.

Dataset Information

Starvation response in Drosophila and its implication for sex specific metabolism and aging

Publications

Purine and folate metabolism as a potential target of sex-specific nutrient allocation in Drosophila and its implication for lifespan-reproduction tradeoff.

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