Project description:The migratory locust, Locusta migratoria, is a serious agricultural pest and important insect model to study insect digestion and feeding behavior. The gut is one of the primary interfaces between the insect and its environment. Nevertheless, knowledge on the gut transcriptome of L. migratoria is still very limited. With the development of two EST databases from L. migratoria (whole body and central nervous system (CNS)) and one EST database from Schistocerca gregaria (CNS), an abundance of transcript data was made available for locusts. In addition, the genome of Locusta was also recently published in an effort to create a better understanding of swarm formation and flight behavior (Wang et al., 2014). While the transcript composition of nervous tissue was relatively well studied after the development of the specific CNS-derived EST-databases from both L. migratoria and S. gregaria, little transcript profiling information is available for the digestive system at the moment. Locusts are, however, widely used as physiological model organisms regarding the regulation and control of feeding and digestion, and improved knowledge on the gut transcriptome could contribute significantly to a better understanding of their gut physiology. Therefore, we aimed to use the available sequence data to specifically identify gut-expressed transcripts in 5th larval locusts. By means of two independent self-self microarray hybridizations for two distinct tissues, the gut and the brain, a selection could be made of those ESTs that are present in the gut and/or the brain. Here, sequences that were found to be expressed in gut but not brain were further functionally annotated to shed new light on the complex physiology of the locust digestive system. Since the gut is the single most important organ in digestion, and both tissues are assumed to be involved in the regulation thereof, the resulting subset of sequences can also be valuable for further in-depth studies on the regulation of digestion. In addition, the method allowed us to rank the signal intensities, using them as a rough indicator to compare relative transcript abundance in the gut. Therefore, the data complement previously published transcript and genomic data, and provide a clear overview of the expressed portion of the genome in the gut. Taken together, the present data provide significant insight into locust larval gut physiology, and will be valuable for future studies on the insect gut.

Project description:BACKGROUND: Olfaction in animals is important for host localization, mating and reproduction in heterogeneous chemical environments. Studying the molecular basis of olfactory receptor neurons (ORNs) systems can elucidate the evolution of olfaction and associated behaviours. Odorant receptors (ORs) in insects have been identified, particularly in the holometabolous model Drosophila, and some of them have been functionally studied. However, ORs in the locust-a hemimetabolous model insect and the most important insect crop pest-have not yet been identified, hindering our understanding of locust olfaction. Here, we report for the first time four putative ORs in Locusta migratoria: LmigOR1, LmigOR2, LmigOR3 and LmigOR4. RESULTS: These four putative OR genes encoded proteins with amino acids of 478, 436, 413 and 403 respectively. Sequence identity among them ranged from 19.7% to 35.4%. All ORs were tissue-specifically expressed in olfactory organs, without sex-biased characteristics. However, LmigOR1, LmigOR3 and LmigOR4 were only expressed in the antenna, while LmigOR2 could also be detected in mouthparts. In situ hybridization demonstrated that the LmigOR1antisense probe labelled olfactory receptor neurons (ORNs) in almost all segments of the antenna, but only a few segments housed ORNs expressing LmigOR2. The number of neurons labelled by LmigOR1 antisense probes in each antennal segment was much greater (>10 neurons/segment) than that labelled by LmigOR2 probes (generally 1-3 neurons/segment). Furthermore, some of the labelled neurons could be attributed to the basiconic sensilla, but LmigOR1 and LmigOR2 were expressed in different subtypes. CONCLUSIONS: Our results strongly suggested that these newly discovered genes encode locust ORs and the differential expression patterns of LmigOR1 and LmigOR2 implied distinct functions. These results may offer insights into locust olfaction and contribute to the understanding of the evolution of insect chemoreception.

Project description:The migratory locust, Locusta migratoria, is a serious agricultural pest and important insect model to study insect digestion and feeding behavior. The gut is one of the primary interfaces between the insect and its environment. Nevertheless, knowledge on the gut transcriptome of L. migratoria is still very limited. With the development of two EST databases from L. migratoria (whole body and central nervous system (CNS)) and one EST database from Schistocerca gregaria (CNS), an abundance of transcript data was made available for locusts. In addition, the genome of Locusta was also recently published in an effort to create a better understanding of swarm formation and flight behavior (Wang et al., 2014). While the transcript composition of nervous tissue was relatively well studied after the development of the specific CNS-derived EST-databases from both L. migratoria and S. gregaria, little transcript profiling information is available for the digestive system at the moment. Locusts are, however, widely used as physiological model organisms regarding the regulation and control of feeding and digestion, and improved knowledge on the gut transcriptome could contribute significantly to a better understanding of their gut physiology. Therefore, we aimed to use the available sequence data to specifically identify gut-expressed transcripts in 5th larval locusts. By means of two independent self-self microarray hybridizations for two distinct tissues, the gut and the brain, a selection could be made of those ESTs that are present in the gut and/or the brain. Here, sequences that were found to be expressed in gut but not brain were further functionally annotated to shed new light on the complex physiology of the locust digestive system. Since the gut is the single most important organ in digestion, and both tissues are assumed to be involved in the regulation thereof, the resulting subset of sequences can also be valuable for further in-depth studies on the regulation of digestion. In addition, the method allowed us to rank the signal intensities, using them as a rough indicator to compare relative transcript abundance in the gut. Therefore, the data complement previously published transcript and genomic data, and provide a clear overview of the expressed portion of the genome in the gut. Taken together, the present data provide significant insight into locust larval gut physiology, and will be valuable for future studies on the insect gut. Self-self hybridisation of Cy5- and Cy3-labeled samples. One biological repeat per tissue type, i.e., brain and gut. Gut is a combination of foregut, midgut, gastric caeca and hindgut. Per tissue type, a pool was made from RNA from 3 pools of 5 locusts, and this for 3 different feeding conditions, resulting in samples derived from a total of 45 locust larvae. Feeding conditions were normally fed, fed with diet containing additional protease inhibitors (PIs), and starved locusts.

Dataset Information

Identification and expression of cuticular protein genes based on Locusta migratoria transcriptome.

Publications

Identification and expression of cuticular protein genes based on Locusta migratoria transcriptome.

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