The potential underlying mechanisms during learning flights.

Hymenopterans, such as bees and wasps, have long fascinated researchers with their sinuous movements at novel locations. These movements, such as loops, arcs, or zigzags, serve to help insects learn their surroundings at important locations. They also allow the insects to explore and orient themselves in their environment. After they gained experience with their environment, the insects fly along optimized paths guided by several guidance strategies, such as path integration, local homing, and route-following, forming a navigational toolkit. Whereas the experienced insects combine these strategies efficiently, the naive insects need to learn about their surroundings and tune the navigational toolkit. We will see that the structure of the movements performed during the learning flights leverages the robustness of certain strategies within a given scale to tune other strategies which are more efficient at a larger scale. Thus, an insect can explore its environment incrementally without risking not finding back essential locations.

Prognostic significance of expression levels of stem cell regulators MSI2 and NUMB in acute myeloid leukemia.

Deregulation of the hematopoietic stem cell (HSC) compartment represents a hallmark of acute myeloid leukemia (AML). Recently, in vivo screening for genes that are involved in the regulation of HSCs has led to the discovery of Musashi-2 (MSI2) as a key regulator of HSCs and as a suppressor of NUMB. In order to analyze the prognostic importance of MSI2 and NUMB expression in AML, MSI2 and NUMB transcript levels from 454 AML patients treated in multicenter trials AML SHG 0199 (ClinicalTrials Identifier NCT00209833) and 0295, and 38 healthy volunteers were analyzed by reverse transcriptase PCR in the context of other molecular markers (NPM1, FLT3, CEBPA, IDH1/IDH2, DNMT3A, NRAS, WT1, KIT, MN1, BAALC, ERG, and WT1). In AML, patients with high MSI2 expression were more likely to be FLT3-ITD positive (P < .001), NPM1 (P < .001), and DNMT3A (P = .003) mutated. Overall survival (OS) was shorter in AML patients with high MSI2 expression (hazard ratio, 1.48; 95 % confidence interval, 1.13-1.95, P = .005). However, relapse-free survival (RFS, P = .15) and complete remission (CR, P = .39) rates were not influenced by MSI2 expression. In multivariate analysis, MSI2 expression remained an independent prognostic factor for OS (P = .03). NUMB expression had no impact on survival (OS, P = .47; RFS, P = .59) and CR rate (P = .39). MSI2 but not NUMB is associated with shorter OS in AML patients and may indicate a more aggressive form of AML.

Prognostic significance of combined MN1, ERG, BAALC, and EVI1 (MEBE) expression in patients with myelodysplastic syndromes.

Overexpression of MN1, ERG, BAALC, and EVI1 (MEBE) genes in cytogenetically normal acute myeloid leukemia (AML) patients is associated with poor prognosis, but their prognostic effect in patients with myelodysplastic syndromes (MDS) has not been studied systematically. Expression data of the four genes from 140 MDS patients were combined in an additive score, which was validated in an independent patient cohort of 110 MDS patients. A high MEBE score, defined as high expression of at least two of the four genes, predicted a significantly shorter overall survival (OS) (HR 2.29, 95 % CI 1.3-4.09, P= .005) and time to AML progression (HR 4.83, 95 % CI 2.01-11.57, P< .001) compared to a low MEBE score in multivariate analysis independent of karyotype, percentage of bone marrow blasts, transfusion dependence, ASXL1, and IDH1 mutation status. In a validation cohort of 110 MDS patients, a high MEBE score predicted shorter OS (HR 1.77; 95 % CI 1.04-3.0, P= .034) and time to AML progression (HR 3.0, 95 % CI 1.17-7.65, P= .022). A high MEBE expression score is an unfavorable prognostic marker in MDS and is associated with an increased risk for progression to AML. Expression of the MEBE genes is regulated by FLI1 and c-MYC, which are potential upstream targets of the MEBE signature.