The classification of esterases: an important gene family involved in insecticide resistance - A review

The use of chemical insecticides continues to play a major role in the control of disease vector populations, which is leading to the global dissemination of insecticide resistance. A greater capacity to detoxify insecticides, due to an increase in the expression or activity of three major enzyme families, also known as metabolic resistance, is one major resistance mechanisms. The esterase family of enzymes hydrolyse ester bonds, which are present in a wide range of insecticides; therefore, these enzymes may be involved in resistance to the main chemicals employed in control programs. Historically, insecticide resistance has driven research on insect esterases and schemes for their classification. Currently, several different nomenclatures are used to describe the esterases of distinct species and a universal standard classification does not exist. The esterase gene family appears to be rapidly evolving and each insect species has a unique complement of detoxification genes with only a few orthologues across species. The examples listed in this review cover different aspects of their biochemical nature. However, they do not appear to contribute to reliably distinguish among the different resistance mechanisms. Presently, the phylogenetic criterion appears to be the best one for esterase classification. Joint genomic, biochemical and microarray studies will help unravel the classification of this complex gene family.

Regulation of the cardiac voltage-gated sodium channel Nav1.5 : regulation of Nav1.5 by ubiquitin-protein ligases of the Nedd4/Nedd4-like family and characterisation of two novel mutations in the gene encoding Nav1.5 (SCN5A) implicated in the Brugada syndrome triggered by fever

Abstract: The genesis of the cardiac action potential, which accounts for the cardiac contraction, is due to the sodium current INa mediated by the voltage-gated sodium channel Nav1.5. Several cardiac arrhythmias such as the Brugada syndrome are known te be caused by mutations in SCN5A, the gene encoding Nav1.5. Studies of these mutations allowed a better understanding of biophysical and functional properties of Nav1.5. However, only few investigations have been performed in order to understand the regulation of Nav1.5. During my thesis, I investigated different mechanisms of regulation of Nav1.5 using a heterologous expression system, HEK293 cells, coupled with a technique of sodium current recording: the patch clamp in whole cell configuration. In previous studies it has been shown that an enzyme of the Nedd4 family (Nedd4-2) regulates an epithelial sodium channel via the interaction with PY-motifs present in the latter. Interestingly, Nav1.5 contains a similar PY-motif, which motivated us to study the role of Nedd4-2 expressed in heart for the regulation of Nav1.5. In a second study, we investigated the implication of two Nav1.5 mutants, which were either less functional or net functional (Nav1.5 R535X and Nav1.5 L325R respectively) implied in the genesis of the Brugada syndrome by fever. Our results established two mechanisms implied in Nav1.5 regulation. The first one implies that following the interaction between the PY-motif of Nav1.5 and Nedd4- 2 Nav1.5 is ubiquitinated by Nedd4-2. This ubiquitination leads to the internalization of Nav1 .5. The second mechanism is a phenomenon called the "dominant negative" effect of Nav1.5 L325R on Nay1.5 where the decrease of 'Na is potentially due to the retention of Nav1.5 by Nav1.5 L325R in an undefined intracellular compartment. These studies defined two mechanisms of Nav1.5 regulation, which could play an important role for the genesis of cardiac arrhythmias where molecular processes are still poorly understood. Résumé La genèse du potentiel d'action cardiaque, permettant la contraction cardiaque, est due au courant sodique INa issu des canaux sodiques cardiaques dépendants du voltage Nav1.5. Nombreuses arythmies cardiaques telles que le syndrome de Brugada sont connues pour être liées à des mutations du gène SCN5A, codant pour Nav1.5. L'étude de ces mutations a permis une meilleure compréhension des propriétés structurelles et fonctionnelles de Nav1.5 et leurs implications dans la genèse de ces pathologies. Néanmoins peu d'études ont été menées afin de comprendre les mécanismes de régulation de Nav1.5. Mon travail de thèse a consisté à étudier des mécanismes de régulation de Nav1.5 en utilisant un système d'expression hétérologue, les cellules HEK293, couplé à une technique d'enregistrement des courants sodiques, le "patch clamp" en configuration cellule entière. La présence sur Nav1.5 d'un motif-PY similaire à ceux nécessaires pour la régulation d'un canal épithélial sodique par une enzyme de la famille de Nedd4, nous a amenée à étudier le rôle de ces ubiquitine-ligases, en particulier Nedd4-2, dans la régulation de Nav1.5. La seconde étude s'est intéressée aux conséquences de deux mutations de SCN5A codant pour deux mutants peu ou pas fonctionnels (Nav1.5 L325R et Nav1.5 R535X respectivement) retrouvées chez des patients présentant un syndrome de Brugada exacerbé par un état fébrile. Nos résultats ont permis d'établir deux mécanismes de régulation de Nav1.5 L'un par Nedd4-2 qui implique rubiquitination de Nav1.5 par cette ligase suite à l'interaction entre le motif-PY de Nav1.5 et Nedd4-2. Cette modification déclenche l'internalisation du canal impliquée dans la diminution d'INa. Le second mécanisme quant à lui est un effet "dominant négatif" de Nav1.5 L325R sur Nav1.5 aboutissant à une diminution d'INa suite à la séquestration intracellulaire potentielle de Nav1.5 par Nav1.5 L325R. Ces études ont mis en évidence deux mécanismes de régulation de Nav1.5 pouvant jouer un rôle majeur dans la genèse et/ou l'accentuation des arythmies cardiaques dont les processus moléculaires au sein des cardiomyocytes, impliquant des modifications du courant sodiques, sont encore mal compris. Résumé destiné à un large public La dépolarisation électrique de la membrane des cellules cardiaques permet la contraction du coeur. La génèse de cette activité électrique est due au courant sodique issu d'un type de canal à sodium situé dans la membrane des cellules cardiaques. De nombreuses pathologies provoquant des troubles du rythme cardiaque sont issues de mutations du gène qui code pour ce canal à sodium. Ces canaux mutants, entrainant diverses pathologies cardiaques telles que le syndrome de Brugada, ont été largement étudiées. Néanmoins, peu de travaux ont été réalisés sur les mécanismes de régulation de ce canal à sodium non muté. Mon travail de thèse a consisté à étudier certains des mécanismes de régulation de ce canal à sodium en utilisant une technique permettant l'enregistrement des courants sodiques issus de l'expression de ces canaux à sodium à la membrane de cellules mammifères. La présence sur ce canal à sodium d'une structure spécifique, similaire à celle nécessaire pour la régulation d'un canal épithélial à sodium par une enzyme appelée Nedd4-2, nous a amenée à étudier le rôle de cette enzyme dans la régulation de ce canal à sodium. La seconde étude s'est intéressée aux rôles de deux mutations du gène codant pour ce canal à sodium retrouvées chez des patients présentant un syndrome de Brugada exacerbé par la fièvre. Nos résultats nous ont permis d'établir deux mécanismes de régulation de ce canal à sodium diminuant le courant sodique l'un par l'action de l'enzyme Nedd4-2, suite à son interaction avec ce canal, qui modifie ce canal à sodium (ubiquitination) diminuant de ce fait la densité membranaire du canal. L'autre par un mécanisme suggérant un effet négatif de l'un des canaux mutants sur l'expression à la membrane du canal à sodium non muté. Ces études ont mis en évidence deux mécanismes de régulation de ce canal à sodium pouvant jouer un rôle majeur dans la genèse et/ou l'accentuation des troubles du rythme cardiaques dont les mécanismes cellulaires sont encore incompris.

Surveillance épidémiologique: une responsabilité du médecin de famille [Epidemiological surveillance: family doctors' responsibility].

Epidemiological surveillance systems are essential and require efficient collaborations between family doctors and public health services. Such a system has to take into account the increase in the number of health problems to be studied. Information gathered at an individual level should imply decisions at a population level which in turn should impact on the individual patient. Epidemiological surveillance requires a well organized, representative and constantly revised system led by motivated, adequately trained doctors.

Family history of cancer: pooled analysis in the International Head and Neck Cancer Epidemiology Consortium.

Alcohol and tobacco consumption are well-recognized risk factors for head and neck cancer (HNC). Evidence suggests that genetic predisposition may also play a role. Only a few epidemiologic studies, however, have considered the relation between HNC risk and family history of HNC and other cancers. We pooled individual-level data across 12 case-control studies including 8,967 HNC cases and 13,627 controls. We obtained pooled odds ratios (OR) using fixed and random effect models and adjusting for potential confounding factors. All statistical tests were two-sided. A family history of HNC in first-degree relatives increased the risk of HNC (OR=1.7, 95% confidence interval, CI, 1.2-2.3). The risk was higher when the affected relative was a sibling (OR=2.2, 95% CI 1.6-3.1) rather than a parent (OR=1.5, 95% CI 1.1-1.8) and for more distal HNC anatomic sites (hypopharynx and larynx). The risk was also higher, or limited to, in subjects exposed to tobacco. The OR rose to 7.2 (95% CI 5.5-9.5) among subjects with family history, who were alcohol and tobacco users. A weak but significant association (OR=1.1, 95% CI 1.0-1.2) emerged for family history of other tobacco-related neoplasms, particularly with laryngeal cancer (OR=1.3, 95% CI 1.1-1.5). No association was observed for family history of nontobacco-related neoplasms and the risk of HNC (OR=1.0, 95% CI 0.9-1.1). Familial factors play a role in the etiology of HNC. In both subjects with and without family history of HNC, avoidance of tobacco and alcohol exposure may be the best way to avoid HNC.

Functional Characterization of a Novel Frameshift Mutation in the C-terminus of the Nav1.5 Channel Underlying a Brugada Syndrome with Variable Expression in a Spanish Family.

INTRODUCTION We functionally analyzed a frameshift mutation in the SCN5A gene encoding cardiac Na(+) channels (Nav1.5) found in a proband with repeated episodes of ventricular fibrillation who presented bradycardia and paroxysmal atrial fibrillation. Seven relatives also carry the mutation and showed a Brugada syndrome with an incomplete and variable expression. The mutation (p.D1816VfsX7) resulted in a severe truncation (201 residues) of the Nav1.5 C-terminus. METHODS AND RESULTS Wild-type (WT) and mutated Nav1.5 channels together with hNavβ1 were expressed in CHO cells and currents were recorded at room temperature using the whole-cell patch-clamp. Expression of p.D1816VfsX7 alone resulted in a marked reduction (≈90%) in peak Na(+) current density compared with WT channels. Peak current density generated by p.D1816VfsX7+WT was ≈50% of that generated by WT channels. p.D1816VfsX7 positively shifted activation and inactivation curves, leading to a significant reduction of the window current. The mutation accelerated current activation and reactivation kinetics and increased the fraction of channels developing slow inactivation with prolonged depolarizations. However, late INa was not modified by the mutation. p.D1816VfsX7 produced a marked reduction of channel trafficking toward the membrane that was not restored by decreasing incubation temperature during cell culture or by incubation with 300 μM mexiletine and 5 mM 4-phenylbutirate. CONCLUSION Despite a severe truncation of the C-terminus, the resulting mutated channels generate currents, albeit with reduced amplitude and altered biophysical properties, confirming the key role of the C-terminal domain in the expression and function of the cardiac Na(+) channel.

Individual, family and environmental factors associated with pediatric excess weight in Spain: a cross-sectional study.

BACKGROUND There is a growing worldwide trend of obesity in children. Identifying the causes and modifiable factors associated with child obesity is important in order to design effective public health strategies.Our objective was to provide empirical evidence of the association that some individual and environmental factors may have with child excess weight. METHOD A cross-sectional study was performed using multi-stage probability sampling of 978 Spanish children aged between 8 and 17 years, with objectively measured height and weight, along with other individual, family and neighborhood variables. Crude and adjusted odds ratios were calculated. RESULTS In 2012, 4 in 10 children were either overweight or obese with a higher prevalence amongst males and in the 8-12 year age group. Child obesity was associated negatively with the socio-economic status of the adult responsible for the child's diet, OR 0.78 (CI95% 0.59-1.00), girls OR 0.75 (CI95% 0.57-0.99), older age of the child (0.41; CI95% 0.31-0.55), daily breakfast (OR 0.59; p = 0.028) and half an hour or more of physical activity every day. No association was found for neighborhood variables relating to perceived neighborhood quality and safety. CONCLUSION This study identifies potential modifiable factors such as physical activity, daily breakfast and caregiver education as areas for public health policies. To be successful, an intervention should take into account both individual and family factors when designing prevention strategies to combat the worldwide epidemic of child excess weight.

Functional and molecular evolutionary analysis of the "Brevix Radix" gene family in mono-and dicotyledonous plants

ABSTRACTIn contrast to animals, plants cannot move from their place of birth and, therefore, need to adapt to their particular habitat in order to survive. Thus, plant development is remarkably plastic, making plants an ideal system for the isolation of genes that account for intraspecific natural variation and possibly environmental adaptation. However, to date, this approach mostly identified null alleles and missed mutations with subtle effects. For instance, BREVIS RADIX (BRX) has been isolated as a key regulator of root growth through a naturally occurring loss-of-function allele in the Arabidopsis thaliana accession Uk-1 and is the founding member of a highly-conserved plant-specific gene family.In this work, we show that a strong selective pressure is acting on the BRX gene family and dates back before the monocot-dicot divergence. However, functional diversification is observed mainly in dicotyledon BRX family genes and is correlated with acceleration in the evolutionary rates in the N-terminal regions. Population genetic data revealed that BRX is highly conserved across Arabidopsis accessions and presents signatures of adaptation. Interestingly, a seven amino acid deletion polymorphism in BRX sequence was found in a few accessions, which seems to be responsible for their enhanced primary root growth. Nevertheless, BRX might not only be active in the root, as suggested by its expression in the shoot. Indeed, leaves and cotyledons of brx mutants are significantly smaller than wild- type. This phenotype is a direct consequence of the absence of BRX function in the shoot rather than an indirect effect of an altered root system growth. Interestingly, cotyledons of brx plants reflect the same physiological defects as the root. Moreover, phenotypes in BRX gain-of-function plants, such as epinastic leaves and increased epidermal cell size, could be associated with an increase in leaf brassinosteroid content.Collectively, these results indicate that BRX contributes to local adaptation by ubiquitously regulating plant growth, probably through the modulation of brassinosteroid biosynthesis.RÉSUMÉContrairement à la plupart des animaux, les plantes ne peuvent se mouvoir et doivent ainsi s'adapter à leur environnement pour survivre. Pour cette raison, elles représentent un système idéal pour l'identification de gènes contribuant à la variation naturelle intra- spécifique, ainsi qu'à l'adaptation. Cependant, cette approche a, jusqu'à présent, surtout permis d'isoler des allèles nuls et non des mutations conférant des effets plus subtiles. C'est le cas du gène Β REVIS RADIX (BRX), un régulateur clé de la croissance racinaire, qui a été identifié grâce à un allèle non-fonctionnel présent dans l'accession naturelle d'Arabidopsis thaliana Uk-1. BRX et ses homologues des plantes mono- et dicotylédones forment une famille très conservée et spécifique aux plantes.Dans ce travail, nous démontrons que la famille de gènes BRX est soumise à une forte pression de sélection qui remonte avant la divergence entre mono- et dicotylédones. Cependant, une diversification fonctionnelle a été observée chez les gènes des dicotylédones et corrèle avec une accélération de la vitesse d'évolution dans leur région N- terminale. Une analyse génétique de différentes accessions naturelles d'Arabidopsis a révélé que BRX est hautement conservé et présente des signatures d'adaptation. Remarquablement, un polymorphisme de délétion de sept acides aminés a été détecté dans quelques accessions et a pour conséquence une plus forte croissance de la racine primaire. Néanmoins, il semble que le rôle de BRX ne se limite pas qu'à la racine, comme indiqué par son expression dans les parties aériennes de la plante. En effet, les mutants brx présentent des cotylédons et des feuilles significativement plus petits que le type sauvage, une conséquence directe de l'absence d'activité de BRX dans ces organes. Nous avons aussi noté que les cotylédons des mutants brx, à l'instar des racines, ont une perception altérée de l'auxine et peuvent être complémentés par l'application exogène de brassinostéroïdes. De plus, dans des plantes présentant un gain de fonction BRX, les feuilles sont épinastiques et les cellules de leur épiderme plus grandes. Ces phénotypes sont accompagnés d'une augmentation de la concentration de brassinostéroïdes dans les feuilles. Conjointement, ces résultats démontrent que BRX contribue à une adaptation locale de la plante par la régulation générale de sa croissance, probablement en modulant la biosynthèse des brassinostéroïdes.

Use of Hy's law and a new composite algorithm to predict acute liver failure in patients with drug-induced liver injury.

BACKGROUND & AIMS Hy's Law, which states that hepatocellular drug-induced liver injury (DILI) with jaundice indicates a serious reaction, is used widely to determine risk for acute liver failure (ALF). We aimed to optimize the definition of Hy's Law and to develop a model for predicting ALF in patients with DILI. METHODS We collected data from 771 patients with DILI (805 episodes) from the Spanish DILI registry, from April 1994 through August 2012. We analyzed data collected at DILI recognition and at the time of peak levels of alanine aminotransferase (ALT) and total bilirubin (TBL). RESULTS Of the 771 patients with DILI, 32 developed ALF. Hepatocellular injury, female sex, high levels of TBL, and a high ratio of aspartate aminotransferase (AST):ALT were independent risk factors for ALF. We compared 3 ways to use Hy's Law to predict which patients would develop ALF; all included TBL greater than 2-fold the upper limit of normal (×ULN) and either ALT level greater than 3 × ULN, a ratio (R) value (ALT × ULN/alkaline phosphatase × ULN) of 5 or greater, or a new ratio (nR) value (ALT or AST, whichever produced the highest ×ULN/ alkaline phosphatase × ULN value) of 5 or greater. At recognition of DILI, the R- and nR-based models identified patients who developed ALF with 67% and 63% specificity, respectively, whereas use of only ALT level identified them with 44% specificity. However, the level of ALT and the nR model each identified patients who developed ALF with 90% sensitivity, whereas the R criteria identified them with 83% sensitivity. An equal number of patients who did and did not develop ALF had alkaline phosphatase levels greater than 2 × ULN. An algorithm based on AST level greater than 17.3 × ULN, TBL greater than 6.6 × ULN, and AST:ALT greater than 1.5 identified patients who developed ALF with 82% specificity and 80% sensitivity. CONCLUSIONS When applied at DILI recognition, the nR criteria for Hy's Law provides the best balance of sensitivity and specificity whereas our new composite algorithm provides additional specificity in predicting the ultimate development of ALF.

Extended family structure in the ant Formica paralugubris: the role of the breeding system

In populations of various ant species, many queens reproduce in the same nest (polygyny), and colony boundaries appear to be absent with individuals able to move fi eely between nests (unicoloniality). Such societies depart strongly from a simple family structure and pose a potential challenge to kin selection theory, because high queen number coupled with unrestricted gene flow among nests should result in levels of relatedness among nestmates close to zero. This study investigated the breeding system and genetic structure of a highly polygynous and largely unicolonial population of the wood ant Formica paralugubris. A microsatellite analysis revealed that nestmate workers, reproductive queens and reproductive males (the queens' mates) are all equally related to each other, with relatedness estimates centring around 0.14. This suggests that most of the queens and males reproducing in the study population had mated within or close to their natal nest, and that the queens did not disperse far after mating. We developed a theoretical model to investigate how the breeding system affects the relatedness structure of polygynous colonies. By combining the model and our empirical data, it was estimated that about 99.8% of the reproducing queens and males originated from within the nest, or from a nearby nest. This high rate of local mating and the rarity of long-distance dispersal maintain significant relatedness among nestmates, and contrast with the common view that unicoloniality is coupled with unrestricted gene flow among nests.

Association of the solute carrier family 11 member 1 gene polymorphisms with susceptibility to leprosy in a Brazilian sample

Natural resistance-associated macrophage protein 1/solute carrier family 11 member 1 gene (Nramp1/Slc11a1) is a gene that controls the susceptibility of inbred mice to intracellular pathogens. Polymorphisms in the human Slc11a1/Nramp1 gene have been associated with host susceptibility to leprosy. This study has evaluated nine polymorphisms of the Slc11a1/Nramp1 gene [(GT)n, 274C/T, 469+14G/C, 577-18G/A, 823C/T, 1029 C/T, 1465-85G/A, 1703G/A, and 1729+55del4] in 86 leprosy patients (67 and 19 patients had the multibacillary and the paucibacillary clinical forms of the disease, respectively), and 239 healthy controls matched by age, gender, and ethnicity. The frequency of allele 2 of the (GT)n polymorphism was higher in leprosy patients [p = 0.04, odds ratio (OR) = 1.49], whereas the frequency of allele 3 was higher in the control group (p = 0.03; OR = 0.66). Patients carrying the 274T allele (p = 0.04; OR = 1.49) and TT homozygosis (p = 0.02; OR = 2.46), such as the 469+14C allele (p = 0.03; OR = 1.53) of the 274C/T and 469+14G/C polymorphisms, respectively, were more frequent in the leprosy group. The leprosy and control groups had similar frequency of the 577-18G/A, 823C/T, 1029C/T, 1465-85G/A, 1703G/A, and 1729+55del4 polymorphisms. The 274C/T polymorphism in exon 3 and the 469+14G/C polymorphism in intron 4 were associated with susceptibility to leprosy, while the allele 2 and 3 of the (GT)n polymorphism in the promoter region were associated with susceptibility and protection to leprosy, respectively.

Inter-informant agreement and prevalence estimates for mood syndromes: Direct interview vs. family history method.

BACKGROUND: The use of the family history method is recommended in family studies as a type of proxy interview of non-participating relatives. However, using different sources of information can result in bias as direct interviews may provide a higher likelihood of assigning diagnoses than family history reports. The aims of the present study were to: 1) compare diagnoses for threshold and subthreshold mood syndromes from interviews to those relying on information from relatives; 2) test the appropriateness of lowering the diagnostic threshold and combining multiple reports from the family history method to obtain comparable prevalence estimates to the interviews; 3) identify factors that influence the likelihood of agreement and reporting of disorders by informants. METHODS: Within a family study, 1621 informant-index subject pairs were identified. DSM-5 diagnoses from direct interviews of index subjects were compared to those derived from family history information provided by their first-degree relatives. RESULTS: 1) Inter-informant agreement was acceptable for Mania, but low for all other mood syndromes. 2) Except for Mania and subthreshold depression, the family history method provided significantly lower prevalence estimates. The gap improved for all other syndromes after lowering the threshold of the family history method. 3) Individuals who had a history of depression themselves were more likely to report depression in their relatives. LIMITATIONS: Low proportion of affected individuals for manic syndromes and lack of independence of data. CONCLUSIONS: The higher likelihood of reporting disorders by affected informants entails the risk of overestimation of the size of familial aggregation of depression.