Sex pheromone signal and stability covary with fitness.

If sexual signals are costly, covariance between signal expression and fitness is expected. Signal-fitness covariance is important, because it can contribute to the maintenance of genetic variation in signals that are under natural or sexual selection. Chemical signals, such as female sex pheromones in moths, have traditionally been assumed to be species-recognition signals, but their relationship with fitness is unclear. Here, we test whether chemical, conspecific mate finding signals covary with fitness in the moth Heliothis subflexa. Additionally, as moth signals are synthesized de novo every night, the maintenance of the signal can be costly. Therefore, we also hypothesized that fitness covaries with signal stability (i.e. lack of temporal intra-individual variation). We measured among- and within-individual variation in pheromone characteristics as well as fecundity, fertility and lifespan in two independent groups that differed in the time in between two pheromone samples. In both groups, we found fitness to be correlated with pheromone amount, composition and stability, supporting both our hypotheses. This study is, to our knowledge, the first to report a correlation between fitness and sex pheromone composition in moths, supporting evidence of condition-dependence and highlighting how signal-fitness covariance may contribute to heritable variation in chemical signals both among and within individuals.

Within-population variability in a moth sex pheromone blend, part 2: selection towards fixation.

To understand how variation in sexual communication systems evolves, the genetic architecture underlying sexual signals and responses needs to be identified. Especially in animals where mating signals are important for mate recognition, and signals and responses are governed by independently assorting genes, it is difficult to envision how signals and preferences can (co)evolve. Moths are a prime example of such animals. In the noctuid moth Heliothis virescens, we found within-population variation in the female pheromone. In previous selection experiments followed by quantitative trait locus (QTL) analysis and expression analysis of candidate desaturase genes, we developed a model involving a trans-acting repressor of the delta-11-desaturase. In our current study with new selection lines, we fixed the most extreme phenotype and found a single underlying mutation: a premature stop codon in the first coding exon of delta-11-desaturase, which we could trace back to its origin in the laboratory. Interestingly, we found no pleiotropic effects of this knock-out mutation on the male physiological or behavioural response, or on growth or fertility. This finding is in contrast to Drosophila melanogaster, where a single desaturase gene affects both female pheromone production and male behavioural response, but similar to other Lepidoptera where these traits are under independent genetic control. To our knowledge, this is the first time that a single point mutation has been identified that underlies the phenotypic variation in the pheromone signal of a moth.

CD34+CD38- leukemic stem cell frequency to predict outcome in acute myeloid leukemia.

Current risk algorithms are primarily based on pre-treatment factors and imperfectly predict outcome in acute myeloid leukemia (AML). We introduce and validate a post-treatment approach of leukemic stem cell (LSC) assessment for prediction of outcome. LSC containing CD34+CD38- fractions were measured using flow cytometry in an add-on study of the HOVON102/SAKK trial. Predefined cut-off levels were prospectively evaluated to assess CD34+CD38-LSC levels at diagnosis (n = 594), and, to identify LSClow/LSChigh (n = 302) and MRDlow/MRDhigh patients (n = 305) in bone marrow in morphological complete remission (CR). In 242 CR patients combined MRD and LSC results were available. At diagnosis the CD34+CD38- LSC frequency independently predicts overall survival (OS). After achieving CR, combining LSC and MRD showed reduced survival in MRDhigh/LSChigh patients (hazard ratio [HR] 3.62 for OS and 5.89 for cumulative incidence of relapse [CIR]) compared to MRDlow/LSChigh, MRDhigh/LSClow, and especially MRDlow/LSClow patients. Moreover, in the NPM1mutant positive sub-group, prognostic value of golden standard NPM1-MRD by qPCR can be improved by addition of flow cytometric approaches. This is the first prospective study demonstrating that LSC strongly improves prognostic impact of MRD detection, identifying a patient subgroup with an almost 100% treatment failure probability, warranting consideration of LSC measurement incorporation in future AML risk schemes.

Comprehensive Protocol to Sample and Process Bone Marrow for Measuring Measurable Residual Disease and Leukemic Stem Cells in Acute Myeloid Leukemia.

Response criteria in acute myeloid leukemia (AML) has recently been re-established, with morphologic examination utilized to determine whether patients have achieved complete remission (CR). Approximately half of the adult patients who entered CR will relapse within 12 months due to the outgrowth of residual AML cells in the bone marrow. The quantitation of these remaining leukemia cells, known as minimal or measurable residual disease (MRD), can be a robust biomarker for the prediction of these relapses. Moreover, retrospective analysis of several studies has shown that the presence of MRD in the bone marrow of AML patients correlates with poor survival. Not only is the total leukemic population, reflected by cells harboring a leukemia associated immune-phenotype (LAIP), associated with clinical outcome, but so is the immature low frequency subpopulation of leukemia stem cells (LSC), both of which can be monitored through flow cytometry MRD or MRD-like approaches. The availability of sensitive assays that enable detection of residual leukemia (stem) cells on the basis of disease-specific or disease-associated features (abnormal molecular markers or aberrant immunophenotypes) have drastically improved MRD assessment in AML. However, given the inherent heterogeneity and complexity of AML as a disease, methods for sampling bone marrow and performing MRD and LSC analysis should be harmonized when possible. In this manuscript we describe a detailed methodology for adequate bone marrow aspirate sampling, transport, sample processing for optimal multi-color flow cytometry assessment, and gating strategies to assess MRD and LSC to aid in therapeutic decision making for AML patients.

Prognostic relevance of immunohistochemical subclassification of diffuse large B-cell lymphoma in two prospective phase III clinical trials.

PURPOSE: Until now molecular biologic techniques have not been easily used in daily clinical practice to stratify patients for therapeutic purposes. Therefore, we have investigated the prognostic relevance of the immunohistochemical (IHC) germinal center B-cell (GCB) versus non-GCB diffuse large B-cell lymphoma (DLBCL) subtypes. PATIENTS AND METHODS: We have analyzed tumor samples from patients treated in 2 prospective multicenter phase III trials, ie HOVON 25 (patients≥65 years, n=153) and HOVON 26 (patients<65 years, n=144) using whole sections (WS) or tissue microarray (TMA). CD10, BCL6, and MUM1 were applied in a specific IHC algorithm. The effect on clinical outcome using WS or TMA and variations in cut-off levels of these markers was also investigated. RESULTS: The GCB subtype was not associated with a better OS in either trial. Small differences were observed in the HOVON 25 trial between techniques, with TMA showing a better outcome for GCB than did WS. Variation of cut-off levels in the specific algorithm did not improve the prediction of clinical outcome. CONCLUSION: We did not observe a consistent predictive power of the GCB and non-GCB classification by IHC in this large series of DLBCL patients treated with CHOP. This underscores the need to determine the biologic variation and the standardization of the protein expression levels and to further study the relevance of prognostic IHC classifications, preferably in phase III clinical trials.

Impact of the tumor microenvironment on prognosis in follicular lymphoma is dependent on specific treatment protocols.

BACKGROUND: The clinical behavior of follicular lymphoma is largely determined by properties of the non-malignant tumor microenvironment. The precise nature of the cell populations is still unclear and published data on their prognostic significance are highly conflicting. This may be partly due to heterogeneous composition and treatments. DESIGN AND METHODS: Pre-treatment biopsy samples of patients with follicular lymphoma treated in an EORTC/BNLI trial comparing fludarabine to cyclophosphamide, vincristine and prednisone (CVP) chemotherapy could be retrieved for 61 patients in five European countries. Immunohistochemical investigations were performed evaluate tumor cell characteristics, T-cell subsets, follicular dendritic cells and macrophages and associations with clinical outcome were studied. RESULTS: Some markers showed a homogeneous prognostic impact, while others had a different nd sometimes opposite effect in the treatment arms. CD69 expression on tumor cells was a poor prognostic sign and an interfollicular infiltrate of FoxP3-positive T cells was a good prognostic sign irrespective of the treatment arm. It is suggestive that a dense infiltrate of FoxP3-positive T cells, dense and interfollicular infiltrate of CD68-positive macrophages and complete follicular dendritic meshworks were associated with a favorable time to progression in CVP-treated patients, while being poor prognostic sign in fludarabine-treated patients. CONCLUSIONS: Our results suggest that characteristic properties of the microenvironment in follicular lymphoma determines the responses to essentially different chemotherapeutic approaches. These data may provide an explanation for the highly conflicting results on immunohistochemical markers and the prognostic role of the microenvironment in follicular lymphoma reported thus far and lay the basis for the development of predictive assays to tailor treatment in patients with follicular lymphoma.