Project description:The relic silverfish Tricholepidion gertschi is the sole extant representative of the family Lepidotrichidae. Its phylogenetic position is of special interest, since it may provide crucial insights into the early phenotypic evolution of the dicondylian insects. However, the phylogenetic position of T. gertschi is unclear. Originally, it was classified among silverfish (Zygentoma), but various alternative relationships within Zygentoma as well as a sistergroup relationship to all remaining Zygentoma + Pterygota are discussed, the latter implying a paraphyly of Zygentoma with respect to Pterygota. Since characters of the head anatomy play a major role in this discussion, we here present the so far most detailed description of the head of T. gertschi based on anatomical studies by synchrotron micro-computer tomography and scanning electron microscopy. A strong focus is put on the documentation of mouthparts and the anatomy of the endoskeleton as well as the muscle equipment. In contrast to former studies we could confirm the presence of a Musculus hypopharyngomandibularis (0md4). The ligamentous connection between the mandibles composed of Musculus tentoriomandibularis inferior (0md6) is also in contact with the anterior tentorium. Phylogenetic analysis of cephalic data results in monophyletic Zygentoma including T. gertschi. Zygentoma are supported by the presence of a set of labial muscles originating at the postocciput, presence of an additional intralabral muscle, and four labial palpomeres. Character systems like the genitalic system, the mating behaviour, the segmentation of the tarsi, the overall body form, and the presence of ocelli which were proposed in other studies as potentially useful for phylogenetic reconstruction are evaluated.
Project description:BackgroundScorpions like other venomous animals possess a highly specialized organ that produces, secretes and disposes the venom components. In these animals, the last postabdominal segment, named telson, contains a pair of venomous glands connected to the stinger. The isolation of numerous scorpion toxins, along with cDNA-based gene cloning and, more recently, proteomic analyses have provided us with a large collection of venom components sequences. However, all of them are secreted, or at least are predicted to be secretable gene products. Therefore very little is known about the cellular processes that normally take place inside the glands for production of the venom mixture. To gain insights into the scorpion venom gland biology, we have decided to perform a transcriptomic analysis by constructing a cDNA library and conducting a random sequencing screening of the transcripts.ResultsFrom the cDNA library prepared from a single venom gland of the scorpion Hadrurus gertschi, 160 expressed sequence tags (ESTs) were analyzed. These transcripts were further clustered into 68 unique sequences (20 contigs and 48 singlets), with an average length of 919 bp. Half of the ESTs can be confidentially assigned as homologues of annotated gene products. Annotation of these ESTs, with the aid of Gene Ontology terms and homology to eukaryotic orthologous groups, reveals some cellular processes important for venom gland function; including high protein synthesis, tuned posttranslational processing and trafficking. Nonetheless, the main group of the identified gene products includes ESTs similar to known scorpion toxins or other previously characterized scorpion venom components, which account for nearly 60% of the identified proteins.ConclusionTo the best of our knowledge this report contains the first transcriptome analysis of genes transcribed by the venomous gland of a scorpion. The data were obtained for the species Hadrurus gertschi, belonging to the family Caraboctonidae. One hundred and sixty ESTs were analyzed, showing enrichment in genes that encode for products similar to known venom components, but also provides the first sketch of cellular components, molecular functions, biological processes and some unique sequences of the scorpion venom gland.
Project description:Co-expression networks and gene regulatory networks (GRNs) are emerging as important tools for predicting the functional roles of individual genes at a system-wide scale. To enable network reconstructions we built a large-scale gene expression atlas comprised of 62,547 mRNAs, 17,862 non-modified proteins, and 6,227 phosphoproteins harboring 31,595 phosphorylation sites quantified across maize development. There was little edge conservation in co-expression and GRNs reconstructed using transcriptome versus proteome data yet networks from either data type were enriched in ontological categories and effective in predicting known regulatory relationships. This integrated gene expression atlas provides a valuable community resource. The networks should facilitate plant biology research and they provide a conceptual framework for future systems biology studies highlighting the importance of studying gene regulation at several levels.