Identification of chemosensory receptor genes in Manduca sexta and knockdown by RNA interference

Insects detect environmental chemicals via a large and rapidly evolving family of chemosensory receptor proteins. Although our understanding of the molecular genetic basis for Drosophila chemoreception has increased enormously in the last decade, similar understanding in other insects remains limited. The tobacco hornworm, Manduca sexta, has long been an important model for insect chemosensation, particularly from ecological, behavioral, and physiological standpoints. It is also a major agricultural pest on solanaceous crops. However, little sequence information and lack of genetic tools has prevented molecular genetic analysis in this species. The ability to connect molecular genetic mechanisms, including potential lineage-specific changes in chemosensory genes, to ecologically relevant behaviors and specializations in M. sexta would be greatly beneficial. Here, we sequenced transcriptomes from adult and larval chemosensory tissues and identified chemosensory genes based on sequence homology. We also used dsRNA feeding as a method to induce RNA interference in larval chemosensory tissues. We report identification of new chemosensory receptor genes including 17 novel odorant receptors and one novel gustatory receptor. Further, we demonstrate that systemic RNA interference can be used in larval olfactory neurons to reduce expression of chemosensory receptor transcripts. Together, our results further the development of M. sexta as a model for functional analysis of insect chemosensation

Solving the Watchman Route Problem on a Grid with Heuristic Search

In this paper we optimally solve the Watchman Route Problem (WRP) on a grid. We are given a grid map with obstacles and the task is to (offline) find a (shortest) path through the grid such that all cells in the map can be visually seen by at least one c ll on the path. WRP is a reminiscent but is different from graph covering and mapping problems which are done online on an unknown graph. We formalize WRP as a heuristic search problem and solve it with an A*-based algorithm. We develop a series of admissible heuristics with increasing difficulty and accuracy. In particular, our heuristics abstract the problem into line-of-sight clusters graph. Then, solutions for the minimum spanning tree (MST) and the traveling salesman problem (TSP) on this graph are used as admissible heuristics for WRP. We theoretically and experimentally study these heuristics and show that we can optimally and suboptimally solve problems of increasing difficulties

Solving the Watchman Route Problem on a Grid with Heuristic Search

In this paper we optimally solve the Watchman Route Problem (WRP) on a grid. We are given a grid map with obstacles and the task is to (offline) find a (shortest) path through the grid such that all cells in the map can be visually seen by at least one cell on the path. We formalize WRP as a heuristic search problem and solve it with an A*-based algorithm. We develop a series of admissible heuristics with increasing difficulty and accuracy. In particular, our heuristics abstract the problem into line-of-sight clusters graph. Then, solutions for the minimum spanning tree (MST) and the traveling salesman problem (TSP) on this graph are used as admissible heuristics for WRP. We theoretically and experimentally study these heuristics and show that we can optimally and suboptimally solve problems of increasing difficulties

Prospective multicenter study of the impact of Oncotype DX colon cancer assay results on treatment recommendations in stage II colon cancer patients

Purpose.The Oncotype DX colon cancer assay is a clinically validated predictor of recurrence risk in stage II colon cancer patients. This prospective study evaluated the impact of recurrence score (RS) results on physician recommendations regarding adjuvant chemotherapy in T3, mismatch repair-proficient (MMR-P) stage II colon cancer patients. Patients and Methods. Stage IIA colon cancer patients were enrolled in 17 centers. Patient tumor specimens were assessed by the RS test (quantitative reverse transcription-polymerase chain reaction) and mismatch repair (immuno-histochemistry). For each patient, the physician\u27s recommended postoperative treatment plan of observation, fluoropyrimidine monotherapy, or combination therapy with oxaliplatin was recorded before and after the RS and mismatch repair results were provided. Results. Of 221 enrolled patients, 141 patients had T3 MMR-P tumors and were eligible for the primary analysis. Treatment recommendations changed for 63 (45%; 95% confidence interval: 36%-53%) of these 141 T3 MMR-P patients, with intensity decreasing for 47 (33%) and increasing for 16 (11%). Recommendations for chemotherapy decreased from 73 patients (52%) to 42 (30%), following review of RS results by physician and patient. Increased treatment intensity was more often observed at higher RS values, and decreased intensity was observed at lower values (p =.011). Conclusion. Compared with traditional clinicopathological assessment, incorporation of the RS result into clinical decision making was associated with treatment recommendation changes for 45% of T3 MMR-P stage II colon cancer patients in this prospective multicenter study. Use of the RS assay may lead to overall reduction in adjuvant chemotherapy use in this subgroup of stage II colon cancer patients. © AlphaMed Press 2014