Interlocking of co-opted developmental gene networks in Drosophila and the evolution of pre-adaptive novelty.

The re-use of genes in new organs forms the base of many evolutionary novelties. A well-characterised case is the recruitment of the posterior spiracle gene network to the Drosophila male genitalia. Here we find that this network has also been co-opted to the testis mesoderm where is required for sperm liberation, providing an example of sequentially repeated developmental co-options. Associated to this co-option event, an evolutionary expression novelty appeared, the activation of the posterior segment determinant Engrailed to the anterior A8 segment controlled by common testis and spiracle regulatory elements. Enhancer deletion shows that A8 anterior Engrailed activation is not required for spiracle development but only necessary in the testis. Our study presents an example of pre-adaptive developmental novelty: the activation of the Engrailed transcription factor in the anterior compartment of the A8 segment where, despite having no specific function, opens the possibility of this developmental factor acquiring one. We propose that recently co-opted networks become interlocked, so that any change to the network because of its function in one organ, will be mirrored by other organs even if it provides no selective advantage to them.

Specification of the endocrine primordia controlling insect moulting and metamorphosis by the JAK/STAT signalling pathway.

The corpora allata and the prothoracic glands control moulting and metamorphosis in insects. These endocrine glands are specified in the maxillary and labial segments at positions homologous to those forming the trachea in more posterior segments. Glands and trachea can be homeotically transformed into each other suggesting that all three evolved from a metamerically repeated organ that diverged to form glands in the head and respiratory organs in the trunk. While much is known about tracheal specification, there is limited information about corpora allata and prothorathic gland specification. Here we show that the expression of a key regulator of early gland development, the snail gene, is controlled by the Dfd and Scr Hox genes and by the Hedgehog and Wnt signalling pathways that induce localised transcription of upd, the ligand of the JAK/STAT signalling pathway, which lies at the heart of gland specification. Our results show that the same upstream regulators are required for the early gland and tracheal primordia specification, reinforcing the hypothesis that they originated from a segmentally repeated organ present in an ancient arthropod.

Brain Atrophy and Clinical Characterization of Adults With Mild Cognitive Impairment and Different Cerebrospinal Fluid Biomarker Profiles According to the AT(N) Research Framework of Alzheimer's Disease.

Introduction: This study aimed to evaluate, in adults with mild cognitive impairment (MCI), the brain atrophy that may distinguish between three AT(N) biomarker-based profiles, and to determine its clinical value. Methods: Structural MRI (sMRI) was employed to evaluate the volume and cortical thickness differences in MCI patients with different AT(N) profiles, namely, A-T-(N)-: normal AD biomarkers; A+T-(N)-: AD pathologic change; and A+T+(N)+: prodromal AD. Sensitivity and specificity of these changes were also estimated. Results: An initial atrophy in medial temporal lobe (MTL) areas was found in the A+T-(N)- and A+T+(N)+ groups, spreading toward the parietal and frontal regions in A+T+(N)+ patients. These structural changes allowed distinguishing AT(N) profiles within the AD continuum; however, the profiles and their pattern of neurodegeneration were unsuccessful to determine the current clinical status. Conclusion: sMRI is useful in the determination of the specific brain structural changes of AT(N) profiles along the AD continuum, allowing differentiation between MCI adults with or without pathological AD biomarkers.

Características clínicas, demográficas e histopatológicas de pacientes postoperados de cáncer colorrectal internados en el Servicio de Coloproctología del Hospital Nacional, Itauguá ­ Paraguay: periodo 2015 y 2018 / Clinical, demographic and histopathological characteristics of postoperative colorectal cancer patients admitted to Servicio de Coloproctología at the Hospital Nacional, Itauguá - Paraguay: period 2015 and 2018

RESUMEN Introducción: el cáncer colorrectal se desarrolla a partir de lesiones precursoras a nivel del colon, recto y ano, siendo responsable del 16,9 % de todas las muertes por cáncer y en los hombres es la tercera neoplasia maligna más común a nivel mundial. Objetivo: caracterizar a los pacientes postoperados de cáncer colorrectal del Servicio de Coloproctología del Hospital Nacional, Itauguá ­ Paraguay en el periodo entre 2015 y 2018. Metodología: estudio observacional descriptivo, retrospectivo de corte transversal. Se utilizaron fichas de pacientes postoperados de cáncer colorrectal del Servicio de Coloproctología del Hospital Nacional, Itauguá ­ Paraguay en el periodo entre 2015 y 2018. Resultados: del total de las 26 fichas de pacientes revisadas, el 70 % fue de sexo masculino y el rango etario más común fue entre 60 - 71 años (52 %); el tipo histológico de cáncer más frecuente fue el adenocarcinoma moderadamente diferenciado 78 %, el estadio más común fue adenocarcinoma de tipo II A (clasificación de la American Joint Committe on Cancer (AJCC-TNM) 65 %, presentó metástasis a distancia 3,81 % y la ubicación de cáncer más frecuente fue el recto 34,78 %. El motivo de consulta más frecuente fue hemorragia 70 %, la complicación más común fue la dehiscencia y no hubo óbitos. Conclusión: el mayor porcentaje de pacientes pertenece al sexo masculino y al grupo etario de mayores a 60 años, fue frecuente el adenocarcinoma moderadamente diferenciado y el estadio más común de tipo II A, la ubicación más frecuente fue el recto y motivo de consulta fue hemorragia (rectorragia)., por lo cual se deberían implementar medidas para la prevención de esta patología.

ABSTRACT Introduction: colorectal cancer develops from precursor lesions in the colon, rectum and anus, being responsible for 16,9 % of all deaths from cancer and in men it is the third most common malignant neoplasm worldwide. Objective: to characterize postoperative colorectal cancer patients of the Coloproctology Service of the Hospital Nacional, Itauguá - Paraguay in the period between 2015 and 2018. Methodology: descriptive, retrospective, cross-sectional observational study. Cards of postoperative colorectal cancer patients from the Coloproctology Service of the Hospital Nacional, Itauguá - Paraguay in the period between 2015 and 2018 were used. Results: of the total of the 26 patient files reviewed, 70 % were male and the most common age range was between 60 - 71 years (52 %); the most frequent histological type of cancer was moderately differentiated adenocarcinoma 78 %, the most common stage was adenocarcinoma type II A (classification of the American Joint Committee on Cancer (AJCC-TNM) 65 %, present distant metastases 3,81 % and the most frequent location of cancer was the rectum 34,78 % .The most frequent reason for consultation was hemorrhage 70 %, the most common complication was dehiscence and there were no deaths. Conclusion: the highest percentage of patients belongs to the male sex and to the age group over 60 years old, moderately differentiated adenocarcinoma was frequent and the most common stage was type II A, the most frequent location was the rectum and the reason for consultation was hemorrhage (rectorrhagia), for which measures must be implemented to prevent this pathology.

Impacto en la mortalidad tras la implantación de una red de atención al infarto agudo de miocardio con elevación del segmento ST. Estudio IPHENAMIC / Impact on mortality after implementation of a network for ST-segment elevation myocardial infarction care. The IPHENAMIC study

INTRODUCCIÓN Y OBJETIVOS: Se sabe muy poco del impacto que las redes de atención del infarto agudo de miocardio con elevación del segmento ST (IAMCEST) tienen en la población. El objetivo de este estudio es averiguar si el PROGALIAM (Programa Gallego de Atención al Infarto Agudo de Miocardio) mejoró la supervivencia en la zona norte de Galicia. MÉTODOS: Se recogieron todos los eventos codificados como IAMCEST entre 2001 y 2013. Se identificó a 6.783 pacientes, divididos en 2 grupos: pre-PROGALIAM (2001-2005), 2.878 pacientes, y PROGALIAM (2006-2013), 3.905 pacientes. RESULTADOS: En la etapa pre-PROGALIAM, la mortalidad ajustada a 5 años fue superior tanto en la población total (HR=1,22; IC95%, 1,14-1,29; p < 0,001), como en cada una de las áreas (A Coruña, HR=1,12; IC95%, 1,02-1,23; p = 0,02; Lugo, HR=1,34; IC95%, 1,2-1,49; p <0,001, y Ferrol, HR=1,23; IC95%, 1,1-1,4; p = 0,001). Antes del PROGALIAM, la mortalidad a 5 años en las áreas de Lugo (HR=0,8; IC95%, 0,67-0,95; p = 0,02) y Ferrol (HR=0,75; IC95%, 0,64-0,88; p = 0,001) era superior que en A Coruña. Estas diferencias desaparecieron tras el desarrollo de la red (Lugo comparado con A Coruña, HR=0,88; IC95%, 0,72-1,06; p = 0,18; Ferrol comparado con A Coruña, HR=1,04; IC95%, 0,89-1,22; p = 0,58. CONCLUSIONES: El desarrollo del PROGALIAM en el área norte de Galicia disminuyó la mortalidad e incrementó la equidad de los pacientes con IAMCEST tanto en general como en cada una de las áreas donde se implantó

INTRODUCTION AND OBJECTIVES: Little is known about the impact of networks for ST-segment elevation myocardial infarction (STEMI) care on the population. The objective of this study was to determine whether the PROGALIAM (Programa Gallego de Atención al Infarto Agudo de Miocardio) improved survival in northern Galicia. METHODS: We collected all events coded as STEMI between 2001 and 2013. A total of 6783 patients were identified and divided into 2 groups: pre-PROGALIAM (2001-2005), with 2878 patients, and PROGALIAM (2006-2013), with 3905 patients. RESULTS: In the pre-PROGALIAM period, 5-year adjusted mortality was higher both in the total population (HR, 1.22, 95%CI, 1.14-1.29; P <.001) and in each area (A Coruña: HR, 1.12; 95%CI, 1.02-1.23; P=.02; Lugo: HR, 1.34; 95%CI, 1.2- 1.49; P <.001 and Ferrol: HR, 1.23; 95%CI, 1.1-1.4; P=.001). Before PROGALIAM, 5-year adjusted mortality was higher in the areas of Lugo (HR, 1.25; 95%CI, 1.05-1.49; P=.02) and Ferrol (HR, 1.32; 95%CI, 1.13-1.55; P=.001) than in A Coruña. These differences disappeared after the creation of the STEMI network (Lugo vs A Coruña: HR, 0.88; 95%CI, 0.72-1.06; P=.18, Ferrol vs A Coruña: HR, 1.04; 95%CI, 0.89-1.22; P=.58. CONCLUSIONS: For patients with STEMI, the creation of PROGALIAM in northern Galicia decreased mortality and increased equity in terms of survival both overall and in each of the areas where it was implemented

Impact on mortality after implementation of a network for ST-segment elevation myocardial infarction care. The IPHENAMIC study.

INTRODUCTION AND OBJECTIVES: Little is known about the impact of networks for ST-segment elevation myocardial infarction (STEMI) care on the population. The objective of this study was to determine whether the PROGALIAM (Programa Gallego de Atención al Infarto Agudo de Miocardio) improved survival in northern Galicia. METHODS: We collected all events coded as STEMI between 2001 and 2013. A total of 6783 patients were identified and divided into 2 groups: pre-PROGALIAM (2001-2005), with 2878 patients, and PROGALIAM (2006-2013), with 3905 patients. RESULTS: In the pre-PROGALIAM period, 5-year adjusted mortality was higher both in the total population (HR, 1.22, 95%CI, 1.14-1.29; P <.001) and in each area (A Coruña: HR, 1.12; 95%CI, 1.02-1.23; P=.02; Lugo: HR, 1.34; 95%CI, 1.2-1.49; P <.001 and Ferrol: HR, 1.23; 95%CI, 1.1-1.4; P=.001). Before PROGALIAM, 5-year adjusted mortality was higher in the areas of Lugo (HR, 1.25; 95%CI, 1.05-1.49; P=.02) and Ferrol (HR, 1.32; 95%CI, 1.13-1.55; P=.001) than in A Coruña. These differences disappeared after the creation of the STEMI network (Lugo vs A Coruña: HR, 0.88; 95%CI, 0.72-1.06; P=.18, Ferrol vs A Coruña: HR, 1.04; 95%CI, 0.89-1.22; P=.58. CONCLUSIONS: For patients with STEMI, the creation of PROGALIAM in northern Galicia decreased mortality and increased equity in terms of survival both overall and in each of the areas where it was implemented. This study was registered at ClinicalTrials.gov (Identifier: NCT02501070).

Descenso del número de angioplastias primarias durante la pandemia y su relación con la mortalidad por COVID-19. El papel de los riesgos competitivos / Decrease in the number of primary angioplasty procedures during the pandemic and its relationship with mortality from COVID-19. The role of competing risks

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Study of Methionine Choline Deficient Diet-Induced Steatosis in Mice Using Endogenous Fluorescence Spectroscopy.

Non-alcoholic fatty liver disease is a highly prevalent condition worldwide that increases the risk to develop liver fibrosis, cirrhosis, and hepatocellular carcinoma. Thus, it is imperative to develop novel diagnostic tools that together with liver biopsy help to differentiate mild and advanced degrees of steatosis. Ex-vivo liver samples were collected from mice fed a methionine-choline deficient diet for two or eight weeks, and from a control group. The degree of hepatic steatosis was histologically evaluated, and fat content was assessed by Oil-Red O staining. On the other hand, fluorescence spectroscopy was used for the assessment of the steatosis progression. Fluorescence spectra were recorded at excitation wavelengths of 330, 365, 385, 405, and 415 nm by establishing surface contact of the fiber optic probe with the liver specimens. A multi-variate statistical approach based on principal component analysis followed by quadratic discriminant analysis was applied to spectral data to obtain classifiers able to distinguish mild and moderate stages of steatosis at the different excitation wavelengths. Receiver Operating Characteristic (ROC) curves were computed to compare classifier's performances for each one of the five excitation wavelengths and steatosis stages. Optimal sensitivity and specificity were calculated from the corresponding ROC curves using the Youden index. Intensity in the endogenous fluorescence spectra at the given wavelengths progressively increased according to the time of exposure to diet. The area under the curve of the spectra was able to discriminate control liver samples from those with steatosis and differentiate among the time of exposure to the diet for most of the used excitation wavelengths. High specificities and sensitivities were obtained for every case; however, fluorescence spectra obtained by exciting with 405 nm yielded the best results distinguishing between the mentioned classes with a total classification error of 1.5% and optimal sensitivities and specificities better than 98.6% and 99.3%, respectively.

Relationship between the Structure and Transport Properties in the Ce1-xLaxO2-x/2 System.

La-doped CeO2 materials have been widely investigated for potential applications in different high-temperature electrochemical devices, such as fuel cells and ceramic membranes for hydrogen production. However, the crystal structure is still controversial, and different models based on fluorite, pyrochlore, and/or type-C structures have been considered, depending on the lanthanum content and synthesis method used. In this work, an exhaustive structural analysis of the Ce1-xLaxO2-x/2 system (0.2 < x ≤ 0.7) is performed with different techniques. The average crystal structure, studied by conventional X-ray diffraction, could be considered to be a disordered fluorite; however, the local structure, examined by electron diffraction and Raman spectroscopy, reveals a biphasic mixture of fluorite and C-type phases. The thermal and electrical properties demonstrate that the materials with x ≥ 0.4 are oxide ion proton conductors in an oxidizing atmosphere and mixed ionic electronic conductors in a reducing atmosphere. The water uptake and proton conductivity increase gradually with the increase in La content, suggesting that the formation of the C-type phase is responsible for the proton conduction in these materials.

Diffuse reflectance spectroscopy accurately discriminates early and advanced grades of fatty liver in mice.

Nonalcoholic fatty liver disease (NAFLD) ranges from steatosis to nonalcoholic steatohepatitis and cirrhosis. Liver biopsy, considered the gold standard to diagnose NAFLD, shows significantly high rates of interobserver variability. Thus there is a need to develop tools that accurately categorize mild and advanced grades of steatosis in order to identify patients at higher risk of developing chronic liver disease. Diffuse reflectance spectroscopy (DRS) has proved to be useful in grading liver fibrosis and cirrhosis, without having been implemented for steatosis. We aim to categorize early and advanced stages of liver steatosis in a methionine-choline deficient (MCD) mouse model. C57bl/6 mice are fed either methionine-choline control or MCD diet during 2 or 8 weeks to induce mild and advanced steatosis. Liver samples are obtained and steatosis is evaluated by oil red O staining. Diffuse reflectance spectra are directly measured on ex vivo liver specimens, in a wavelength range of 400 to 800 nm. DRS is able to discriminate between early or advanced steatosis and healthy hepatic tissue with negligible error while showing high average sensitivity and specificity (0.94 and 0.95, respectively). Our results suggest that liver steatosis can be accurately evaluated by DRS, highlighting the importance of applied spectroscopic methods in assessing NAFLD.

Theranostic-PDT with the antibody anti isoform 4 SOD mitocondrial labeled with PpIX in the lung cancer cell line A-549.

BACKGROUND: In this work, a drug product composed of an IgM antibody derived from a hybridoma subclone 4C1F6D5G7B8 was prepared and further labeled with PpIX to be used in cell lines A-549 and MRC-5. The aim of this work was to evaluate the potential theranostic activity of the obtained product together with photodynamic therapy (PDT). METHODS: The IgM antibody labeled with PpIX was used in different concentrations to perform theranostics with PDT in cell lines A-549 and MRC-5 in order to identify the specificity of IgM antibody in lung cancer cells by means of a LED-irradiation system set at 630 nm. The location of the conjugate was further determined by confocal microscopy. RESULTS: The theranostic with conjugate Ab-PpIX in the A-549 cell lines showed fluorescence by confocal microscopy, whereas the MRC-5 cell line showed no reactivity. The PDT with the conjugate in the cell line A-549 decreased its viability 70% compared to the control. On the contrary, with the MRC-5 cell line no viability diference was shown. The confocal microscopy applied to the cell line A-549 showed that the Ab-PpIX was majorly located at the cytoplasm. CONCLUSION: Ab-PpIX showed therapeutical potential in lung cancer cells A-549 and had no activity in non-cancerous lung cells (MCR-5).

Nuclear fallout provides a new link between aPKC and polarized cell trafficking.

BACKGROUND: Cell polarity, essential for cell physiology and tissue coherence, emerges as a consequence of asymmetric localization of protein complexes and directional trafficking of cellular components. Although molecules required in both processes are well known their relationship is still poorly understood. RESULTS: Here we show a molecular link between Nuclear Fallout (Nuf), an adaptor of Rab11-GTPase to the microtubule motor proteins during Recycling Endosome (RE) trafficking, and aPKC, a pivotal kinase in the regulation of cell polarity. We demonstrate that aPKC phosphorylates Nuf modifying its subcellular distribution. Accordingly, in aPKC mutants Nuf and Rab11 accumulate apically indicating altered RE delivery. We show that aPKC localization in the apico-lateral cortex is dynamic. When we block exocytosis, by means of exocyst-sec mutants, aPKC accumulates inside the cells. Moreover, apical aPKC concentration is reduced in nuf mutants, suggesting aPKC levels are maintained by recycling. CONCLUSIONS: We demonstrate that active aPKC interacts with Nuf, phosphorylating it and, as a result, modifying its subcellular distribution. We propose a regulatory loop by which Nuf promotes aPKC apical recycling until sufficient levels of active aPKC are reached. Thus, we provide a novel link between cell polarity regulation and traffic control in epithelia.

Exercise left ventricular ejection fraction predicts events in right bundle branch block.

OBJECTIVE: Interpretation of the electrocardiogram (ECG) during exercise is not easy in patients with right bundle branch block (RBBB). Also, the value of exercise echocardiography (ExE) for predicting outcome in them has not been addressed. We sought to assess its prognostic value in patients with RBBB and known/suspected coronary disease. DESIGN: Retrospective analysis of data on 703 patients with RBBB who were submitted to a clinically-indicated ExE. The end points were overall mortality and combined myocardial infarction and cardiovascular mortality. RESULTS: During follow-up (4.1 ± 4.5 years) there were 130 deaths and 108 combined events. Independent predictors of combined events were history of coronary artery disease (hazard ratio [HR] = 2.37, 95% Confidence Interval [CI] = 1.24-4.52, p = 0.009) resting wall motion score index (HR = 2.14, 95% CI = 1.12-4.10, p = 0.02), metabolic equivalents (HR = 0.89, 95% CI = 0.93-0.97, p = 0.007), Δ in double product with exercise (HR = 0.96, 95% CI = 0.92-1.00, p = 0.036) and Δ in left ventricular ejection fraction (LVEF) with exercise (HR = 0.97, 95% CI = 0.94-0.99, p = 0.01). Neither positive clinical nor ECG exercise testing was predictive. Combined event rates were 3.3% in patients with ΔLVEF > 5%, 4.7% in those with ΔLVEF between 1-5% and 8.2% in those with no increase (Δ < 1%). CONCLUSIONS: A decrease in LVEF during exercise is predictive of serious events in patients with RBBB.

JAK/STAT and Hox Dynamic Interactions in an Organogenetic Gene Cascade.

Organogenesis is controlled by gene networks activated by upstream selector genes. During development the gene network is activated stepwise, with a sequential deployment of successive transcription factors and signalling molecules that modify the interaction of the elements of the network as the organ forms. Very little is known about the steps leading from the early specification of the cells that form the organ primordium to the moment when a robust gene network is in place. Here we study in detail how a Hox protein induces during early embryogenesis a simple organogenetic cascade that matures into a complex gene network through the activation of feedback and feed forward interaction loops. To address how the network organization changes during development and how the target genes integrate the genetic information it provides, we analyze in Drosophila the induction of posterior spiracle organogenesis by the Hox gene Abdominal-B (Abd-B). Initially, Abd-B activates in the spiracle primordium a cascade of transcription factors and signalling molecules including the JAK/STAT signalling pathway. We find that at later stages STAT activity feeds back directly into Abd-B, initiating the transformation of the Hox cascade into a gene-network. Focusing on crumbs, a spiracle downstream target gene of Abd-B, we analyze how a modular cis regulatory element integrates the dynamic network information set by Abd-B and the JAK/STAT signalling pathway during development. We describe how a Hox induced genetic cascade transforms into a robust gene network during organogenesis due to the repeated interaction of Abd-B and one of its targets, the JAK/STAT signalling cascade. Our results show that in this network STAT functions not just as a direct transcription factor, but also acts as a "counter-repressor", uncovering a novel mode for STAT directed transcriptional regulation.

Diffuse reflectance spectroscopy as a possible tool to complement liver biopsy for grading hepatic fibrosis in paraffin-preserved human liver specimens.

A diffuse reflectance spectroscopy-based method to score fibrosis in paraffin-preserved human liver specimens has been developed and is reported here. Paraffin blocks containing human liver tissue were collected from the General Hospital of Mexico and included in the study with the patients' written consent. The score of liver fibrosis was determined in each sample by two experienced pathologists in a single-blind fashion. Spectral measurements were acquired at 450-750 nm by establishing surface contact between the optical probe and the preserved tissue. According to the histological evaluation, four liver samples showed no evidence of fibrosis and were categorized as F0, four hepatic specimens exhibited an initial degree of fibrosis (F1-F2), five liver specimens showed a severe degree of fibrosis (F3), and six samples exhibited cirrhosis (F4). The human liver tissue showed a characteristic diffuse reflectance spectrum associated with the progressive stages of fibrosis. In the F0 liver samples, the diffuse reflection intensity gradually increased in the wavelength range of 450-750 nm. In contrast, the F1-F2, F3, and F4 specimens showed corresponding 1.5-, 2-, and 5.5-fold decreases in the intensity of diffuse reflectance compared to the F0 liver specimens. At 650 nm, all the stages of liver fibrosis were clearly distinguished from each other with high sensitivity and specificity (92-100%). To our knowledge, this is the first study reporting a distinctive diffuse reflectance spectrum for each stage of fibrosis in paraffin-preserved human liver specimens. These results suggest that diffuse reflectance spectroscopy may represent a complementary tool to liver biopsy for grading fibrosis.

Src kinases mediate the interaction of the apical determinant Bazooka/PAR3 with STAT92E and increase signalling efficiency in Drosophila ectodermal cells.

Intercellular communication depends on the correct organization of the signal transduction complexes. In many signalling pathways, the mechanisms controlling the overall cell polarity also localize components of these pathways to different domains of the plasma membrane. In the Drosophila ectoderm, the JAK/STAT pathway components are highly polarized with apical localization of the receptor, the associated kinase and the STAT92E protein itself. The apical localization of STAT92E is independent of the receptor complex and is due to its direct association with the apical determining protein Bazooka (Baz). Here, we find that Baz-STAT92E interaction depends on the presence of the Drosophila Src kinases. In the absence of Src, STAT92E cannot bind to Baz in cells or in whole embryos, and this correlates with an impairment of JAK/STAT signalling function. We believe that the requirement of Src proteins for STAT92E apical localization is mediated through Baz, as we can co-precipitate Src with Baz but not with STAT92E. This is the first time that a functional link between cell polarity, the JAK/STAT signalling pathway and the Src kinases has been established in a whole organism.

Antagonism versus cooperativity with TALE cofactors at the base of the functional diversification of Hox protein function.

Extradenticle (Exd) and Homothorax (Hth) function as positive transcriptional cofactors of Hox proteins, helping them to bind specifically their direct targets. The posterior Hox protein Abdominal-B (Abd-B) does not require Exd/Hth to bind DNA; and, during embryogenesis, Abd-B represses hth and exd transcription. Here we show that this repression is necessary for Abd-B function, as maintained Exd/Hth expression results in transformations similar to those observed in loss-of-function Abd-B mutants. We characterize the cis regulatory module directly regulated by Abd-B in the empty spiracles gene and show that the Exd/Hth complex interferes with Abd-B binding to this enhancer. Our results suggest that this novel Exd/Hth function does not require the complex to bind DNA and may be mediated by direct Exd/Hth binding to the Abd-B homeodomain. Thus, in some instances, the main positive cofactor complex for anterior Hox proteins can act as a negative factor for the posterior Hox protein Abd-B. This antagonistic interaction uncovers an alternative way in which MEIS and PBC cofactors can modulate Abd-B like posterior Hox genes during development.