ABSTRACT: The aim of this study was to elucidate which changes in gene expression are related to the induced anti-herbivory response in the brown seaweed Fucus vesiculosus. Microarray hybridizations were used to identify genes differentially expressed in response to grazing by the isopod Idotea baltica. This study shows that modifications in gene expression occur simultaneously to a reduced palatability and that defence induction entails reallocation of resources from primary to secondary metabolism with down-regulation of photosynthesis and degradation of storage compounds. Total RNA of Fucus vesiculosus pieces that were or were not previously grazed by Idotea baltica for 15 and 18 days (3 biological replicates each) was hybridized against pooled RNA from 4 F. vesiculosus pieces that were collected before onset of grazing (day 0).
Project description:The aim of this study was to elucidate changes in gene expression related to the induced anti-herbivory response in the brown seaweed Fucus vesiculosus. Microarray hybridizations were used to identify genes differentially expressed in response to grazing by the periwinkle Littorina obtusata. This study shows that modifications in gene expression occur simultaneously to a reduced palatability and that defence induction entails reallocation of resources from primary to secondary metabolism with down-regulation of photosynthesis. Total RNA of Fucus vesiculosus pieces that were or were not previously grazed by Littorina obtusata for 3, 12, 15, 21, and 24 days (5 biological replicates each) was hybridized against pooled RNA from 5 F. vesiculosus pieces that were collected before onset of grazing (day 0).
Project description:Background: Complex biological networks control fundamental processes such as reproduction. The relationship of network structure to biological function was investigated in a global gene interaction network developed from ovary tissues of the model fish, fathead minnow (Pimephales promelas). Results: A global ovary gene interaction network was inferred from gene expression in ovaries of fathead minnow representing 288 different exposure conditions and 1,472 microarrays. More than 74 percent of the interactions in two subnetworks and 37% of the connections in a third subnetwork were also present as known connections found in curated databases and the literature. Subnetworks within the network were enriched in specific pathways and key ovarian functions. The network location of differentially expressed genes from different ovary stages was consistent with known functional changes at those stages. The global network provide additional insight into gene function when gene directly linked to differentially expressed genes are considered in enrichment analysis. Analysis of the impact of bisphenol A on ovarian gene expression demonstrated that the network provides an informative frame work in which to investigate mechanisms by which chemical effects occur. Conclusions: Our results suggest that the ovary transcriptional network is composed of several connected subnetworks where each is enriched in specific functions. Construction of a global gene regulatory network from multiple experiments provides valuable insight into the function of genes and the impact of chemicals on biological systems. total RNA from the ovary tissue of treated or control fish labeled in single color was hybridized to Agilent fathead minnow microarray (design 019597)
Project description:Human skeletal tissue contains an abundance of proteins some of which may be preserved over geological timescales. The profiling of proteins from ancient individuals — or palaeoproteomics —has begun to provide new information about the diseases suffered in past societies. We describe here the first dental palaeoproteomic profiles of Iron Age individuals, collected from the site of Long Long Rak rockshelter in northwest Thailand. We recovered amino acid sequences for thousands of proteins preserved in their dental tissue, however, it is evident that these palaeoproteomic profiles comprise a palimpsest of modifications that occurred both ante-mortem and post-mortem. Palaeoproteomic profiles are able to categorise disease and show the capacity of these individuals for harboring a variety of illnesses prior to death. Here we apply for the first time palaeoproteomic analysis to five prehistoric human teeth from Southeast Asia. We combine this method with stable isotope analysis using δ18O and δ13C values to broadly identify the diet of these individuals. The specimens were collected from log coffins contained within the Iron Age site of Long Long Rak (LLR) rockshelter in Pang Mapha district, Mae Hong Son Province, northwest Thailand.. Radiocarbon dating shows these log coffins to date within the range of 1,960±30 cal. yr BP to 1,636±44 cal. yr BP.
Project description:Precise frequency discrimination is a hallmark of auditory function in birds and mammals. In the cochlea, tuning and spectral separation result from longitudinal differences in basilar membrane stiffness and numerous individual gradiations in sensory hair cell phenotypes, but it is unknown what patterns those phenotypes. Hypothesizing that morphogen levels might differ along the longitudinal axis of the developing cochlea, we sequenced the transcriptomes of the proximal, middle, and distal thirds of the chicken cochlea at E6.5, when postmitotic hair cells first form. Embryonic day 6.5 chicken cochlea were dissected. Three samples were collected from each cochlear duct by cutting the duct into three approximately equal sized pieces to produce proximal, middle, and distal pieces. Each sample contained a portion of the future tegmentum vasculosum and the basilar papilla sensory epithelium. The distal piece also contained the region fo the future lagena.
Project description:Fathead minnow and zebrafish are among the most intensively studied fish species in environmental toxicogenomics. To aid the assessment and interpretation of subtle transcriptomic effects from treatment conditions of interest, there needs to be a better characterization and understanding of the natural variation in gene expression among fish individuals within populations. Little effort, however, has been made in this area. Leveraging the transcriptomics data from a number of our toxicogenomics studies conducted over the years, we conducted a meta-analysis of nearly 600 microarrays generated from the ovary tissue of untreated, reproductively mature fathead minnow and zebrafish samples. As expected, there was considerable batch-to-batch transcriptomic variation; this “batch-effect” appeared to impact the fish transcriptomes randomly. The overall level of variation within-batch was quite low in fish ovary tissue, making it a suitable system for studying chemical stressors with subtle biological effects. The within-batch variation, however, differed considerably among individual genes and molecular pathways. This difference in variability is probably both technical and biological, thus suggesting a need to take into account both the expression levels and variance in evaluating and interpreting the transcriptional impact on genes and pathways by experimental conditions. There was significant conservation of both the genomes and transcriptomes between fathead minnow and zebrafish. The conservation to such a degree would enable not only a comparative biology approach in studying the mechanisms of action underlying environmental stressors, but also effective sharing of a large amount of existing public transcriptomics data for future development of toxicogenomics applications. total RNA from the ovary tissue of treated or control fish labeled in single color was hybridized to Agilent fathead minnow microarray (design 019597)
Project description:In birds and mammals, all mesoderm cells are generated from the primitive streak. Nascent mesoderm cells contain unique dorso-ventral (D/V) identities depending on their relative ingression position along the streak. Molecular mechanisms controlling this initial phase of mesoderm diversification are not well-understood. Using chick model, we generated high-quality transcriptomic datasets of different streak regions and analyzed their molecular heterogeneity. Streak tissues were dissected from stage-matched HH4 chick embryos and were further divided into four equal pieces along its anterio-posterior length (termed “A”, “B”, “C” and “D”, with “A” representing most anterior and therefore most dorsal and “D” most posterior and therefore most ventral). Each of the four regions was represented by three independent samples (n=3), with each sample containing 5-7 μg total RNA derived from 85-93 pooled pieces. 5 μg of RNA from each sample were used to screen Affymetrix Chicken Genome Array without an amplification step.
Project description:Brown algae (Phaeophyceae) are complex photosynthetic organisms with a very different evolutionary history to green plants, to which they are only distantly related. These seaweeds are the dominant species in rocky coastal ecosystems and they exhibit many interesting adaptations to these, often harsh, environments. The brown algae are also important because they are one of only a very small number of eukaryotic lineages that have evolved complex multicellularity. This work used whole genome tiling array approach to generate a comprehensive transcriptome map of the filamentous seaweed Ectocarpus siliculosus (Dillwyn) Lyngbye, a model organism for the brown algae. Keywords: high-resolution tiling array, brown algae, ectocarpus The slides were hybridised with two, labelled samples: 1) a mixture of labelled cDNA corresponding to RNA samples from mature sporophytes and gametophytes and from immature sporophytes stressed either in high salt medium or by addition of hydrogen peroxide and 2) genomic DNA as a control.