Response to temperature increase is genotype-dependent: A genomic analysis of marine larvae
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ABSTRACT: We produced differentially sensitive-temperature phenotypes using genetically defined larval families of the bivalve Crassostrea gigas. Larval growth rates varied ~5-fold and reciprocal hybrids showed different genotype-dependent responses over a 15-25°C temperature range. Whole-genome expression analysis of ~24 million cDNAs from larvae identified 22,250 unique transcripts. Of these, ~15% showed a significant interaction between genotype and temperature and are associated with genotype-dependent differences in response to temperature. Examination of 2 genotypes of Pacific oyster larvae, grown at 3 temperatures
Project description:Biomphalaria glabrata infection by the Schistosoma mansoni free-swimming miracidium and its subsequent development to the parasitic sporocyst stage is critical to establishment of viable infections and triggers a variety of physiological, biochemical and molecular changes. Here, we describe a genome-wide analysis of the S. mansoni miracidium and developing sporocyst. Keywords: life-cycle, development, host-interaction We generated transcriptomic profiles of the developing larval stages of Schistosoma mansoni using long serial analysis of gene expression (LongSAGE). Five cDNA libraries were constructed from miracidia and in vitro cultured 6- and 20-day old sporocysts maintained in sporocyst medium (SM) or in SM conditioned by previous cultivation with cells of the B. glabrata embryonic (Bge) cell line. From five libraries, 314,799 SAGE tags were sequenced and resulted in a total of 21,440 unique sequence tags. A total of 254 tags were differentially expressed during “conditioned” development and 236 tags were differentially expressed during “un-conditioned” development. In addition, 53 tags were found to be differentially expressed between 6-day conditioned and unconditioned sporocysts and 42 tags between 20-day conditioned and unconditioned sporocysts.
Project description:The host range of African trypanosomes is influenced by innate protective molecules in the blood of primates. A subfraction of human high-density lipoprotein (HDL) containing apolipoprotein A-I, apolipoprotein L-I, and haptoglobin-related protein is toxic to Trypanosoma brucei brucei but not the human sleeping sickness parasite Trypanosoma brucei rhodesiense. It is thought that T. b. rhodesiense evolved from a T. b. brucei-like ancestor and expresses a defense protein that ablates the antitrypanosomal activity of human HDL. To directly investigate this possibility, we developed an in vitro selection to generate human HDL-resistant T. b. brucei. Here we show that conversion of T. b. brucei from human HDL sensitive to resistant correlates with changes in the expression of the variant surface glycoprotein (VSG) and abolished uptake of the cytotoxic human HDLs. Complete transcriptome analysis of the HDL-susceptible and -resistant trypanosomes confirmed that VSG switching had occurred but failed to reveal the expression of other genes specifically associated with human HDL resistance, including the serum resistance-associated gene (SRA) of T. b. rhodesiense. In addition, we found that while the original active expression site was still utilized, expression of three expression site-associated genes (ESAG) was altered in the HDL-resistant trypanosomes. These findings demonstrate that resistance to human HDLs can be acquired by T. b. brucei. Keywords: Trypanosoma, VSG, antigenic switching, HDL-resistance Bloodstream stages of the Lister strain 427 T. b. brucei (MiTat 1.2), expressing VSG221, were used in these studies. Cells were cultured in HMI-9 medium with the addition of heat inactivated fetal bovine serum (FBS) (10%) and Serum Plus (10%). T. b. brucei 427-221 is an antigenically stable line and contains a single copy of the vsg221 gene within the 221 expression site (221ES). At a cell density of approximately 1,000,000 cells/ml, T. b. brucei 427-221 were exposed to various amounts of human HDLs for 24 h in a 6 well plate. Surviving trypanosomes were counted using a hemocytometer then diluted into fresh HMI-9 medium and allowed to recover for 5-14 days. Once the cells had grown to a density of approximately 1,000,000 cells/ml, they were once again incubated with human HDLs. Each round of selection was performed with increasing concentrations of human HDLs and freezer stocks were prepared for each surviving population. Over nine months we conducted eight rounds of human HDL selection, resulting in a population of T. b. brucei that survived incubation with 800 μl of human HDLs (160 lytic U).
Project description:The abundant and widespread coccolithophore Emiliania huxleyi plays an important role in mediating CO2 exchange between the ocean and the atmosphere through its impact on marine photosynthesis and calcification. Here, we use long serial analysis of gene expression (SAGE) to identify E. huxleyi genes responsive to nitrogen (N) or phosphorus (P) starvation. Long SAGE is an elegant approach for examining quantitative and comprehensive gene expression patterns without a priori knowledge of gene sequences via the detection of 21-bp nucleotide sequence tags. E. huxleyi appears to have a robust transcriptional-level response to macronutrient deficiency, with 42 tags uniquely present or up-regulated twofold or greater in the N-starved library and 128 tags uniquely present or up-regulated twofold or greater in the P-starved library. The expression patterns of several tags were validated with reverse transcriptase PCR. Roughly 48% of these differentially expressed tags could be mapped to publicly available genomic or expressed sequence tag (EST) sequence data. For example, in the P-starved library a number of the tags mapped to genes with a role in P scavenging, including a putative phosphate-repressible permease and a putative polyphosphate synthetase. In short, the long SAGE analyses have (i) identified many new differentially regulated gene sequences, (ii) assigned regulation data to EST sequences with no database homology and unknown function, and (iii) highlighted previously uncharacterized aspects of E. huxleyi N and P physiology. To this end, our long SAGE libraries provide a new public resource for gene discovery and transcriptional analysis in this biogeochemically important marine organism. Keywords: Emiliania, gene expression, nutrients, SAGE, phosphate, nitrogen Emiliania huxleyi CCMP 1516 was obtained from the Provasoli-Guillard Center for the Culture of Marine Phytoplankton, Bigelow Laboratories. Cultures were grown at 18°C on a 14 h:10 h light:dark cycle (140 µmol quanta m-2 s-1). Nitrogen and phosphate replete (Replete: 35 µM NO3- and 1.5 µM PO43-), low nitrogen (-N: 10 µM NO3-) and low phosphate (-P: 0 µM PO43-) cells were grown in f/50 medium without Si. Locally collected seawater was filtered (pore size, 0.2 µm) and autoclaved. Filter-sterilized inorganic nutrients, trace metals and vitamins (thiamin, biotin and B12) were added after autoclaving. The cells were grown in 8 L batch cultures. The growth of cultures was monitored daily by cell number counted on a hemacytometer, and by relative fluorescence using a Turner Designs AU Fluorometer. Replete cells were harvested in mid-log phase while –N and –P cells were harvested at the onset of stationary phase for SAGE analysis.
Project description:Nitric oxide (NO) is a gaseous intercellular signaling molecule that also plays a role in host-parasite relations. NO acts rapidly, either via regulation of soluble guanylate cyclase, or by direct interactions with enzymes and other proteins, and has also been shown to have effects on gene expression. Here, we use SAGE (Serial Analysis of Gene Expression) to identify NO-responsive changes in gene expression in Schistosoma mansoni following a 3 hour exposure to sodium nitroprusside, an NO donor. Overall, these results indicate that NO does not rapidly induce large-scale changes in schistosome gene expression, but that expression of particular genes of interest appear to respond to NO. Keywords: Schistosoma, SAGE, NOS, nitric oxide, gene expression Adult S. mansoni perfused from infected Swiss-Webster female mice (obtained from the NIAID Schistosomiasis Resource Center) 42-49 days postinfection were maintained in culture (RPMI medium) overnight and then exposed for 3 hours to either 1 mM sodium nitroprusside (SNP), a well-characterized NO donor, or to RPMI alone. Worms remained viable and motile following treatment. Total RNA was extracted with Trizol (Invitrogen) and treated with DNAse 1 (Ambion) to remove contaminating genomic DNA, and Long-SAGE libraries constructed.
Project description:Phosphorus (P) is a critical driver of phytoplankton growth and ecosystem structure and function in the ocean. Diatoms are an abundant and widespread functional group of phytoplankton that are responsible for significant amounts of primary production in the ocean, however there has not been a comprehensive study of diatom physiological responses to P deficiency. Here, we coupled deep sequencing of transcript tags and quantitative proteomic analysis from the diatom Thalassiosira pseudonana grown under P-replete and P-deficient conditions. The reads (tags) were mapped to the T. pseudonana genome sequence, confirming expression of 91% of the modeled gene set. A total of 318 genes were differentially regulated with a false discovery rate of p<0.05. A total of 1264 proteins were detected, and of those 136 were differentially expressed with a false discovery rate of p<0.05. Significant changes in the abundance of transcripts and proteins were observed and these changes were coordinated for glycolysis, translation, and multiple biochemical responses to P deficiency. These data demonstrate that diatom P deficiency results in changes in cellular P allocation through polyphosphate production, increased P transport, a switch to utilization of dissolved organic P (DOP) through increased production of alkaline phosphatase metalloenzymes and a diesterase, and a remodeling of the cell surface through production of sulfolipids. Together, these findings reveal that T. pseudonana has evolved a sophisticated response to P deficiency involving multiple biochemical strategies that are likely critical to its ability to rapidly respond to variations in environmental P availability. T. pseudonana (Strain 1335 from the Provosoli-Guillard National Center for the Culture of Marine Phytoplankton (CCMP)) was grown in a modified f/2 medium made from Sargasso Sea water. Macronutrients and vitamin B12, biotin, and thiamine solutions were treated with prepared Chelex-100 resin to remove trace metal contaminants followed by trace-metal clean syringe sterilization to yield final nutrient concentrations of 882 μM NaNO3 and 106 μM Na2SiO3, and vitamin concentrations of 75 pM, 400 pM, and 60 nM, respectively. The Fe concentration was also modified from f/2 to 400 nM. All conditions were run in triplicate at 14 ºC, in constant light (120 µmol photons m-2 s-1). Cells were grown with f/2 phosphorus concentrations (P-replete; 36 µM PO4) and with low phosphorus concentrations (P-deficient; 0.4 µM PO4). Growth was monitored daily with cell counts. Duplicate P-replete treatments were pooled and harvested in mid log phase, and triplicate P-deficient treatments were pooled, and also quickly harvested onto 2 µm filters at the onset of P depletion. All RNA samples were snap frozen in liquid nitrogen. Replicate P-deficient cultures were refed to 36 µM phosphate at the onset of P depletion, and subsequently resumed growth. Additional growth studies were performed as described above substituting glycerolphosphate and adenosine monophosphate at 36 µM, for the phosphate in the medium.
Project description:Relatively little is known about the presence and regulation of pathways involved in nutrient acquisition in the brown tide forming alga, Aureococcus anophagefferens. In this study, Long-SAGE (Serial Analysis of Gene Expression) was used to profile the A. anophagefferens transcriptome under nutrient replete (control), and nitrogen (N) and phosphorus (P) deficiency with the goal of understanding how this organism responds at the transcriptional level to varying nutrient conditions. This approach has aided A. anophagefferens genome annotation efforts and identified a suite of genes up-regulated by N and P deficiency, some of which have known roles in nutrient metabolism. Genes up-regulated under N deficiency include an ammonium transporter, an acetamidase/formamidase, and two peptidases. This suggests an ability to utilize reduced N compounds and dissolved organic nitrogen, supporting the hypothesized importance of these N sources in A. anophagefferens bloom formation. There are also a broad suite of P-regulated genes, including an alkaline phosphatase, and two 5’-nucleotidases, suggesting A. anophagefferens may use dissolved organic phosphorus under low phosphate conditions. These N- and P-regulated genes may be important targets for exploring nutrient controls on bloom formation in field populations. Aureococcus anophagefferens CCMP 1984 was obtained from the Provasoli-Guillard Center for the Culture of Marine Phytoplankton (CCMP). The cultures were grown at 18C on a 14 h:10 h light:dark cycle (140 µmol quanta m-2 s-1). Nitrogen- and phosphate-replete (883 µM NO3- and 36.3 µM PO43-) cells, –N (40 µM NO3-) cells, and –P (1 µM PO43-) cells were grown in autoclaved L1 media with no Si (Guillard and Hargraves 1993), prepared using 0.2 µm filtered Vineyard Sound seawater. Vitamins (thiamine, biotin, and B12) were sterile filtered and added to the media after autoclaving. Replete cells were harvested during mid log phase of growth, while –N and –P cells were harvested at the onset of stationary phase when N or P was depleted.
Project description:Adult male grass shrimp were exposed for 96 hours to LC50 concentrations of either Fipronil, Endosulfan, or Cadmium, as well as a Carrier Control exposure. RNA was extracted from whole-body homogenates using the RNABee kit. Tags were clustered to identify tags diagnostic of the different exposures. Keywords: SAGE, Grass shrimp, ecotoxicogenomics 3 randomly selected shrimp were pooled for each library. Libraries were constructed using the I-SAGE long kit from Invitrogen.
Project description:Increasing evidence suggests that low-abundant transcripts may play fundamental roles in biological processes. In an attempt to estimate the prevalence of low-abundant transcripts in eukaryotic genomes, we performed a transcriptome analysis in Drosophila using the SAGE technique. We collected 244,313 SAGE tags from transcripts expressed in Drosophila embryonic, larval, pupae, adult, and testicular tissue. From these SAGE tags, we identified 40,823 unique SAGE tags. Our analysis showed that 55% of the 40,823 unique SAGE tags are novel without matches in currently known Drosophila transcripts, and most of the novel SAGE tags have low copy numbers. Further analysis indicated that these novel SAGE tags represent novel low-abundant transcripts expressed from loci outside of currently annotated exons including the intergenic and intronic regions, and antisense of the currently annotated exons in the Drosophila genome. Our study reveals the presence of a significant number of novel low-abundant transcripts in Drosophila, and highlights the need to isolate these novel low-abundant transcripts for further biological studies. Keywords: other
Project description:Pulmonary microvascular endothelial cells were cultured on the inner surface of fibers (each 700 µm inner diameter) coated with either with native- or advanced glycation endproduct (AGE) modified fibronectin in hollow-fiber cartridges (FiberCell Systems, Inc.). Duration of shear stress application was 10 days. Shear stress was gradually increased to 17 dyne/cm2 in 2 samples (GSM32266: native fibronectin high shear stress or GSM45608: AGE-fibronectin) or was kept at constant low level of 1 dyne/cm2 in 1 sample (GSM41248: native fibronectin low shear stress). Keywords: parallel sample
Project description:We produced differentially sensitive-temperature phenotypes using genetically defined larval families of the bivalve Crassostrea gigas. Larval growth rates varied ~5-fold and reciprocal hybrids showed different genotype-dependent responses over a 15-25°C temperature range. Whole-genome expression analysis of ~24 million cDNAs from larvae identified 22,250 unique transcripts. Of these, ~15% showed a significant interaction between genotype and temperature and are associated with genotype-dependent differences in response to temperature.