Project description:Despite a significant increase in genomic data, our knowledge of gene functions and their transcriptional responses to environmental stimuli remains limited. Here, we use the model keystone species Daphnia pulex to study environmental responses of genes in the context of their gene family history to better understand the relationship between genome structure and gene function in response to environmental stimuli. Daphnia were exposed to five different treatments, each consisting of a diet supplemented with one of five cyanobacterial species, and a control treatment consisting of a diet of only green algae. Differential gene expression profiles of Daphnia exposed to each of these five cyanobacterial species showed that genes with known functions are more likely to be shared by different expression profiles whereas genes specific to the lineage of Daphnia are more likely to be unique to a given expression profile. Furthermore, while only a small number of non-lineage specific genes was conserved across treatment type, there was a high degree of overlap in expression profiles at the functional level. The conservation of functional responses across the different cyanobacterial treatments can be attributed to the treatment specific expression of different paralogous genes within the same gene family. Comparison with available gene expression data in the literature suggests differences in nutritional composition in diets with cyanobacterial species compared to diets of green algae as a primary driver for cyanobacterial effects on Daphnia. We conclude that conserved functional responses in Daphnia across different cyanobacterial treatments are mediated through alternate regulation of paralogous gene families. Whole transcriptome dual color arrays were used to discover differentially expressed genes following sub-lethal exposure to five cyanobacteria in D. pulex. RNA was isolated from eight independent and concurrently replicated exposures of Daphnia to control and five cyanobacteria conditions. RNA was hybridized to microarrays using a standard, control vs. treated design that included dye swaps. Cyanobacteria were Anabaena (ANA), Aphanizomenon (Aph), Cylindrospermopsis (Cyl), Nodularia (Nod) and Oscillatoria (Osl).
Project description:Resistance to herbicides in weeds can be due to alteration(s) in the gene encoding the herbicide target site, or to herbicide degradation via a deviation in plant general metabolism. If target-site-based resistance is easy to study, the multigenic control of metabolism-based resistance renders it much more complex to study. Metabolism-based resistance to herbicides represents the major part of herbicide resistance in black-grass. Its most likely basis is an overexpression of genes encoding enzymes degrading herbicides. We thus seek to identify such overexpressed genes by comparing the transcriptomes of resistant and sensitive black-grass individuals belonging to an F2 line segregating for two resistance genes. Given there are no genomic tools developed for black-grass, this approach will use heterologous hybridisation onto a wheat Affymetrix microarray. Comparison using heterologous hybridisation onto a wheat whole-genome microarray of transcriptome of three pools of black-grass plants obtained 2h30 after herbicide spraying at field rate. The three pools correspond to: · Sensitive plants (killed by herbicide). · Moderately resistant plants (growth impaired by herbicide but plants still alive) · Resistant plants (growth unimpaired by herbicide)
Project description:Bronchopulmonary dysplasia (BPD) is the most common chronic respiratory disease in premature infants. Recent studies have highlighted the contribution of genetic factors to BPD susceptibility. Our aim was to identify the genetic variants associated to BPD, through a genomewide association study. Two discovery series were performed, using a DNA pooling-based strategy in Caucasian and black African neonates. DNA pooling studies were performed in two discovery series. The first discovery series was made up of 22 Caucasian infants with BPD and 76 Caucasian controls. The second discovery series was composed of 21 black African infants with BPD and 86 black African controls. Equimolar amounts of each DNA sample were then added to either the case or control pool, for each series. To control for experimental errors, several independent sets of pools were constructed. Concerning the Caucasian series, 3 sets of identical pools were constructed with one made in double quantity in order to hybridize it twice, which led to 4 independent replicates. Concerning the black African series, 4 sets of identical pools were constructed and each was hybridized once, leading also to 4 independent replicates. Genotyping was performed using the Infinium II Illumina HumanHap300 Genotyping BeadChip array for the Caucasian population and the Illumina HumanHap650Y array for the black African population. Each replicate was hybridized once which led to 4 arrays for each case and control pools and for each population. A total of 16 arrays were performed. technical replicate: Sample 1, Sample 2, Sample 3, Sample 4 technical replicate: Sample 5, Sample 6, Sample 7, Sample 8 technical replicate: Sample 9, Sample 10, Sample 11, Sample 12 technical replicate: Sample 13, Sample 14, Sample 15, Sample 16
Project description:Cyanobacteria fix atmospheric CO2 to biomass and through metabolic engineering can also act as photosynthetic cell factories for sustainable productions of fuels and chemicals. The Calvin cycle is the primary pathway for CO2 fixation in cyanobacteria, algae and C3 plants, and several studies have shown that overexpression of a cyanobacterial Calvin cycle enzyme, bifunctional sedoheptulose-1,7-bisphosphatase/fructose-1,6-bisphosphatase (hereafter BiBPase), enhances CO2 fixation in both plants and algae, although its impact on cyanobacteria has not yet been rigorously studied. Here, we show that overexpression of BiBPase enhanced growth, cell size, and photosynthetic O2 evolution of the cyanobacterium Synechococcus sp. PCC 7002 in an environment with elevated CO2 concentration. Biochemical analysis, immunodetection, and proteomic analysis revealed that overexpression of BiBPase considerably elevated the cellular activities of two rate-limiting enzymes in the Calvin cycle, namely ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) and aldolase, while it repressed several enzymes involved in the respiratory carbon metabolism (e.g. glycolysis and the oxidative pentose phosphate pathway) including glucose-6-phosphate dehydrogenase. Concomitantly, the content of glycogen was significantly reduced while the extracellular carbohydrate content increased. These results indicate that overexpression of BiBPase leads to global reprogramming of carbon metabolism in Synechococcus sp. PCC 7002, promoting photosynthetic carbon fixation and repressing the respiratory carbon catabolism, while altering carbohydrate partitioning.
Project description:Resistance to herbicides in weeds can be due to alteration(s) in the gene encoding the herbicide target site, or to herbicide degradation via a deviation in plant general metabolism. If target-site-based resistance is easy to study, the multigenic control of metabolism-based resistance renders it much more complex to study. Metabolism-based resistance to herbicides represents the major part of herbicide resistance in black-grass. Its most likely basis is an overexpression of genes encoding enzymes degrading herbicides. We thus seek to identify such overexpressed genes by comparing the transcriptomes of resistant and sensitive black-grass individuals belonging to an F2 line segregating for two resistance genes. Given there are no genomic tools developed for black-grass, this approach will use heterologous hybridisation onto a wheat Affymetrix microarray. Comparison using heterologous hybridisation onto a wheat whole-genome microarray of transcriptome of three pools of black-grass plants obtained 2h30 after herbicide spraying at field rate. The three pools correspond to: · Sensitive plants (killed by herbicide). · Moderately resistant plants (growth impaired by herbicide but plants still alive) · Resistant plants (growth unimpaired by herbicide) 6 arrays - wheat
Project description:A series of dual-channel gene expression profiles obtained using Agilent Mouse TOE 75k microarrays was used to examine the sex-dependent differences in gene expression across three outbred mouse strains, 129J x Black Swiss, 129J x BALB/c, and ICR. This series is comprised of samples obtained from 3 pools of randomly chosen independent cDNA samples of male and female 129Jx BALB/c mice and 3 randomly chosen independent cDNA samples of male and female 129J x Black Swiss mice and 5 randomly chosen independent cDNA samples of male and female ICR mice. The ICR mice were randomly distributed into three and two member pools for each sex and two of the 5 samples for each sex were independently hybridized separately as well. Comparison of the sex-specific genes for the three outbred strains generated lists of strain-dependent and strain-independent sex-specific genes. Keywords: sex response and strain response