Insights on the role of acetaldehyde and other aldehydes in the odour and tactile nasal perception of red wine.

Wine models with or without a dearomatised and lyophilized red wine extract containing a young red aroma base (control) plus one vector with one or several aroma compounds (unsaturated-aldehydes, saturated-aldehydes, benzaldehyde, isoamyl-alcohol, methoxypyrazines and (Z)-1,5-octadien-3-one) were prepared. Models were spiked with increasing amounts of acetaldehyde whose headspace concentrations were controlled. Odour and nasal chemesthesic properties were assessed by a trained sensory panel. Results confirm the contribution of the different players, notably isoamyl-alcohol, (Z)-1,5-octadien-3-one, benzaldehyde and methoxypyrazines, to wine aroma and tactile nasal characteristics and demonstrate that acetaldehyde levels play an outstanding role in their modulation. At low levels, it can play positive roles in some specific aromatic contexts, while at higher levels, enhance the negative effects associated to the generic presence of other aldehydes (saturated, unsaturated and Strecker aldehydes) by enhancing "green vegetable" notes and "itching" character and the "burning" effects linked to high levels of isoamyl alcohol.

Genotype-specific interactions between parasitic arthropods.

Despite the ubiquity of coinfection, we know little of the effects of intra-specific genetic variability on coinfection by distinct parasite species. Here we test the hypothesis that parasite multiplication depends on the combination of parasite genotypes that coinfect the host (that is Genotype.parasite × Genotype.parasite interaction). To that aim, we infected tomato leaves with the ecto-parasitic mites Tetranychus urticae and Tetranychus evansi. We tested all possible combinations between four T. urticae and two T. evansi populations sampled on different hosts or localities. There was no universal (that is genotype-independent) effect of coinfection on mite multiplication; in many cases the two species had no effect on each other. However, several combinations of T. evansi and T. urticae populations led to elevated T. evansi numbers. Similarly, T. urticae reproduction largely depended on the interaction between T. urticae and T. evansi populations. This evidence for genotype-by-genotype interaction between coinfecting parasites indicates that the effect of coinfection on parasite epidemiology and evolution may vary in space according to the genetic composition of local parasite populations; it further suggests the possibility of coevolution between parasites species that share the same hosts.

Combining experimental evolution and field population assays to study the evolution of host range breadth.

Adapting to specific hosts often involves trade-offs that limit performance on other hosts. These constraints may either lead to narrow host ranges (i.e. specialists, able to exploit only one host type) or wide host ranges often leading to lower performance on each host (i.e. generalists). Here, we combined laboratory experiments on field populations with experimental evolution to investigate the impact of adaptation to the host on host range evolution and associated performance over this range. We used the two-spotted spider mite, Tetranychus urticae, a model organism for studies on the evolution of specialization. Field mite populations were sampled on three host plant species: tomato, citrus tree and rosebay (Nerium oleander). Testing these populations in the laboratory revealed that tomato populations of mites could exploit tomato only, citrus populations could exploit citrus and tomato whereas Nerium populations could exploit all three hosts. Besides, the wider niche ranges of citrus and Nerium populations came at the cost of low performance on their non-native hosts. Experimental lines selected to live on the same three host species exhibited similar patterns of host range and relative performance. This result suggests that adaptation to a new host species may lead to wider host ranges but at the expense of decreased performance on other hosts. We conclude that experimental evolution may reliably inform on evolution in the field.

Environmental risk assessment for plant pests: a procedure to evaluate their impacts on ecosystem services.

The current methods to assess the environmental impacts of plant pests differ in their approaches and there is a lack of the standardized procedures necessary to provide accurate and consistent results, demonstrating the complexity of developing a commonly accepted scheme for this purpose. By including both the structural and functional components of the environment threatened by invasive alien species (IAS), in particular plant pests, we propose an environmental risk assessment scheme that addresses this complexity. Structural components are investigated by evaluating the impacts of the plant pest on genetic, species and landscape diversity. Functional components are evaluated by estimating how plant pests modify ecosystem services in order to determine the extent to which an IAS changes the functional traits that influence ecosystem services. A scenario study at a defined spatial and temporal resolution is then used to explore how an IAS, as an exogenous driving force, may trigger modifications in the target environment. The method presented here provides a standardized approach to generate comparable and reproducible results for environmental risk assessment as a component of Pest Risk Analysis. The method enables the assessment of overall environmental risk which integrates the impacts on different components of the environment and their probabilities of occurrence. The application of the proposed scheme is illustrated by evaluating the environmental impacts of the invasive citrus long-horn beetle, Anoplophora chinensis.

Social immunity in honeybees (Apis mellifera): transcriptome analysis of varroa-hygienic behaviour.

Honeybees have evolved a social immunity consisting of the cooperation of individuals to decrease disease in the hive. We identified a set of genes involved in this social immunity by analysing the brain transcriptome of highly varroa-hygienic bees, who efficiently detect and remove brood infected with the Varroa destructor mite. The function of these candidate genes does not seem to support a higher olfactory sensitivity in hygienic bees, as previously hypothesized. However, comparing their genomic profile with those from other behaviours suggests a link with brood care and the highly varroa-hygienic Africanized honeybees. These results represent a first step toward the identification of genes involved in social immunity and thus provide first insights into the evolution of social immunity.

Reproductive performance of seven strains of the tomato red spider mite Tetranychus evansi (Acari: Tetranychidae) at five temperatures.

The tomato red spider mite Tetranychus evansi Baker et Pritchard occurs on solanaceous plants, and causes serious damage to a variety of crops in Africa and Europe. In 2001 this species was also found in Japan, on nightshade (Solanum nigrum L.), and its invasion to solanaceous of agricultural importance is feasible. To evaluate its potential severity as a pest, the present study assessed the life-history parameters, such as the rate of development and the intrinsic rate of natural increase (r(m)), on S. nigrum for T. evansi collected on seven sites worldwide. Increasing temperatures between 15 and 32.5°C significantly increased the developmental rate of the seven strains while immature developmental duration was about the same at 32.5-40°C. The rate of egg-to-adult development [(% hatch) × (% survival)] exceeded 88% at temperatures between 15 and 37.5°C. The lower thermal thresholds (LT) were 11.9-12.5°C for both egg-to-adult and egg-to-egg development. The optimum developmental temperatures ranged from 36.7 to 43.8°C and the upper developmental threshold (UT) ranged from 45.2 to 59.4°C. The r (m)-values became higher with temperature increasing from 15 to 35°C. The r (m)-values at 25°C ranged from 0.265 to 0.277 which are relatively high for species of the genus Tetranychus. These results indicate that T. evansi after invasion into Japan has the potential to become a serious pest on solanaceous crops, just the same as in Africa and Europe.

Modeling quality of premium spanish red wines from gas chromatography-olfactometry data.

The aroma compositions of 25 premium Spanish red wines have been screened by quantitative gas chromatography-olfactometry and have been related to the quality scores of the wines. The study has shown that up to 65 odorants can be present in the aroma profiles of those wines, 32 of which have been detected in less than half of the samples. One new odorant is reported for the first time in wine [(Z)-2-nonenal], and only 11 odorants, most of them weak and infrequent, remain unknown. Quality was not positively correlated with any single compound or with any olfactometric vector built by the summation of odorants with similar odors. However, an olfactometric vector built by the summation of the olfactometric scores of defective odorants, such as 2-methoxy-3,5-dimethylpyrazine, 4-ethylphenol, 3-ethylphenol, 2,4,6-trichloroanisole, and o-cresol was significant and negatively related to quality. Quality could be satisfactorily explained by a simple partial least-squares model (79% explained variance in cross-validation) with just three X-variables: the aforementioned defective vector, a second vector grouping 9 other compounds with negative aroma nuances, and the fruity vector, grouping 15 compounds with fruit-sweet descriptors. This result shows that the quality of these red wines is primarily related to the presence of defective or negative odorants, and secondarily to the presence of a relatively large number of fruit-sweet odorants. Remarkably, only in a few low-quality samples could defective aroma nuances be detected, which suggests that defective and negative odorants exert a strong aroma suppression effect on fruity aroma.

Climate change: impact on honey bee populations and diseases.

The European honey bee, Apis mellifera, is the most economically valuable pollinator of agricultural crops worldwide. Bees are also crucial in maintaining biodiversity by pollinating numerous plant species whose fertilisation requires an obligatory pollinator. Apis mellifera is a species that has shown great adaptive potential, as it is found almost everywhere in the world and in highly diverse climates. In a context of climate change, the variability of the honey bee's life-history traits as regards temperature and the environment shows that the species possesses such plasticity and genetic variability that this could give rise to the selection of development cycles suited to new environmental conditions. Although we do not know the precise impact of potential environmental changes on honey bees as a result of climate change, there is a large body of data at our disposal indicating that environmental changes have a direct influence on honey bee development. In this article, the authors examine the potential impact of climate change on honey bee behaviour, physiology and distribution, as well as on the evolution of the honey bee's interaction with diseases. Conservation measures will be needed to prevent the loss of this rich genetic diversity of honey bees and to preserve ecotypes that are so valuable for world biodiversity.

Differential gene expression of the honey bee Apis mellifera associated with Varroa destructor infection.

BACKGROUND: The parasitic mite, Varroa destructor, is the most serious pest of the western honey bee, Apis mellifera, and has caused the death of millions of colonies worldwide. This mite reproduces in brood cells and parasitizes immature and adult bees. We investigated whether Varroa infestation induces changes in Apis mellifera gene expression, and whether there are genotypic differences that affect gene expression relevant to the bee's tolerance, as first steps toward unravelling mechanisms of host response and differences in susceptibility to Varroa parasitism. RESULTS: We explored the transcriptional response to mite parasitism in two genetic stocks of A. mellifera which differ in susceptibility to Varroa, comparing parasitized and non-parasitized full-sister pupae from both stocks. Bee expression profiles were analyzed using microarrays derived from honey bee ESTs whose annotation has recently been enhanced by results from the honey bee genome sequence. We measured differences in gene expression in two colonies of Varroa-susceptible and two colonies of Varroa-tolerant bees. We identified a set of 148 genes with significantly different patterns of expression: 32 varied with the presence of Varroa, 116 varied with bee genotype, and 2 with both. Varroa parasitism caused changes in the expression of genes related to embryonic development, cell metabolism and immunity. Bees tolerant to Varroa were mainly characterized by differences in the expression of genes regulating neuronal development, neuronal sensitivity and olfaction. Differences in olfaction and sensitivity to stimuli are two parameters that could, at least in part, account for bee tolerance to Varroa; differences in olfaction may be related to increased grooming and hygienic behavior, important behaviors known to be involved in Varroa tolerance. CONCLUSION: These results suggest that differences in behavior, rather than in the immune system, underlie Varroa tolerance in honey bees, and give an indication of the specific physiological changes found in parasitized bees. They provide a first step toward better understanding molecular pathways involved in this important host-parasite relationship.

[The neuropsychological profile of mild cognitive impairment with involvement of multiple cognitive areas. The importance of amnesia in distinguishing two subtypes of patients]. / Perfil neuropsicológico del deterioro cognitivo leve con afectación de múltiples áreas cognitivas. Importancia de la amnesia en la distinción de dos subtipos de pacientes.

INTRODUCTION: The use of diagnostic criteria for mild cognitive impairment (MCI) that do not require the presence of amnesia enables patients to be classified into three types of MCI: pure amnestic MCI (aMCI), MCI with involvement of multiple cognitive functions and amnesia (mf-aMCI) and MCI with involvement of multiple cognitive functions without amnesia, or non-amnestic MCI (mf-nonaMCI). AIM: To determine whether patients with MCI with involvement of multiple functions (mfMCI) have a different profile of cognitive involvement depending on whether amnesia is present or not. PATIENTS AND METHODS: Out of a total sample of 175 patients with MCI, we studied 138 with mfMCI. Of these, 109 (79%) had memory disorders (mf-aMCI) and 29 (21%) did not (mf-nonaMCI). For each group of patients, we determined the percentage who scored below normal in each of the items on the abbreviated Barcelona test. RESULTS: Patients with mf-aMCI failed more frequently in temporal orientation, naming and semantic category evocation tests. Patients with mf-nonaMCI failed more often in motor praxis and abstraction tests. Differences were statistically significant. Additionally, it was noted that patients with mf-nonaMCI tended to make more mistakes in attention tests. CONCLUSIONS: The presence of amnesia allows us to identify an mf-aMCI group with a cognitive profile suggesting temporal involvement, unlike the mf-nonaMCI group, whose members have a cognitive profile that suggests subcortical compromise.

Perfil neuropsicológico del deterioro cognitivo leve con afectación de múltiples áreas cognitivas. Importancia de la amnesia en la distinción de dos subtipos de pacientes / The neuropsychological profile of mild cognitive impairment with involvement of multiple cognitive areas. The importance of amnesia in distinguishing two subtypes of patients

Introducción. El uso de criterios diagnósticos de deterioro cognitivo leve (DCL) que no exigen la presencia de amnesia, permite clasificar a los pacientes en tres tipos de DCL: DCL amnésico puro (DCLa), DCL con afectación de múltiples funciones cognitivas y amnesia (DCLmf-A) y DCL con afectación de múltiples funciones cognitivas sin amnesia o DCL no amnésico (DCLmf-noA). Objetivo. Determinar si los pacientes con DCL con afectación de múltiples funciones (DCLmf) tienen un perfil de afectación cognitiva distinto en función de la presencia o no de amnesia. Pacientes y métodos. De un total de 175 pacientes con DCL, estudiamos a 138 con DCLmf. De ellos, 109 (79%) tenían afectación de la memoria (DCLmf-A) y 29 (21%) no la presentaban (DCLmf-noA). Para cada grupo determinamos el porcentaje de pacientes que tenían una puntuación inferior a la normal en cada uno de los elementos del test Barcelona abreviado. Resultados. Los pacientes con DCLmf-A fallaban con más frecuencia en los tests de orientación temporal, denominación y evocación categorial semántica. Los pacientes con DCLmf-noA fallaban más en las pruebas de praxis motora y abstracción. Las diferencias eran estadísticamente significativas. Además, se apreciaba una tendencia mayor a cometer errores en las pruebas de atención por parte de los pacientes con DCLmf-noA. Conclusiones. La presencia de amnesia permite identificar a un grupo de DCLmf-A con un perfil cognitivo sugestivo de afectación temporal, diferente del grupo de DCLmf-noA con perfil cognitivo, que sugiere afectación subcortical

Introduction. The use of diagnostic criteria for mild cognitive impairment (MCI) that do not require the presence of amnesia enables patients to be classified into three types of MCI: pure amnestic MCI (aMCI), MCI with involvement of multiple cognitive functions and amnesia (mf-aMCI) and MCI with involvement of multiple cognitive functions without amnesia, or non-amnestic MCI (mf-nonaMCI). Aim. To determine whether patients with MCI with involvement of multiple functions (mfMCI) have a different profile of cognitive involvement depending on whether amnesia is present or not. Patients and methods. Out of a total sample of 175 patients with MCI, we studied 138 with mfMCI. Of these, 109 (79%) had memory disorders (mf-aMCI) and 29 (21%) did not (mf-nonaMCI). For each group of patients, we determined the percentage who scored below normal in each of the items on the abbreviated Barcelona test. Results. Patients with mf-aMCI failed more frequently in temporal orientation, naming and semantic category evocation tests. Patients with mf-nonaMCI failed more often in motor praxis and abstraction tests. Differences were statistically significant. Additionally, it was noted that patients with mf-nonaMCI tended to make more mistakes in attention tests. Conclusions. The presence of amnesia allows us to identify an mf-aMCI group with a cognitive profile suggesting temporal involvement, unlike the mf-nonaMCI group, whose members have a cognitive profile that suggests subcortical compromise

Prevalence of interstitial lung involvement in patients with connective tissue diseases assessed with high-resolution computed tomography.

OBJECTIVES: To assess the prevalence of interstitial lung disease (ILD) in patients with different forms of connective tissue disease (CTD) using non-invasive procedures including high-resolution computed tomography (HRCT) and to evaluate the relationship between the imaging and functional status of the patients. METHODS: Eighty-one subjects with CTD (47 inpatients and 34 outpatients) were evaluated with pulmonary function tests (PFT) and radiological investigations. The extent and severity of lung disease was quantified with an HRCT scoring system previously used in patients with systemic sclerosis (SSc). Interstitial lung involvement was defined as predominantly fibrotic or inflammatory based on HRCT abnormalities. RESULTS: HRCT abnormalities suggestive of ILD were observed in 69 patients (85.1%), whereas PFT and plain radiograph alterations occurred less frequently (40.7%). The most frequent HRCT abnormalities were septal/subpleural lines and ground-glass appearance whereas lesions consistent with advanced fibrosis were observed in a minority of patients. The HRCT score was higher in patients with abnormal PFT (p<0.001). Thirty-five patients had predominant fibrosis and 34 patients predominantly inflammatory abnormalities. A score of 10 points represented the best compromise between sensitivity and specificity in predicting functional impairment. CONCLUSIONS: A high prevalence of ILD was found based on HRCT abnormalities. However, HRCT scans characterized by minor abnormalities have poor specificity for clinically significant disease and functional findings should also be considered. The large number of patients with predominantly inflammatory HRCT abnormalities suggests that many cases of ILD may be diagnosed in a relatively early stage of the disease.

The invasive coconut mite Aceria guerreronis (Acari: Eriophyidae): origin and invasion sources inferred from mitochondrial (16S) and nuclear (ITS) sequences.

Over the past 30 years the coconut mite Aceria guerreronis Keifer has emerged as one of the most important pests of coconut and has recently spread to most coconut production areas worldwide. The mite has not been recorded in the Indo-Pacific region, the area of origin of coconut, suggesting that it has infested coconut only recently. To investigate the geographical origin, ancestral host associations, and colonization history of the mite, DNA sequence data from two mitochondrial and one nuclear region were obtained from samples of 29 populations from the Americas, Africa and the Indo-ocean region. Mitochondrial DNA 16S ribosomal sequences were most diverse in Brazil, which contained six of a total of seven haplotypes. A single haplotype was shared by non-American mites. Patterns of nuclear ribosomal internal transcribed spacer (ITS) variation were similar, again with the highest nucleotide diversity found in Brazil. These results suggest an American origin of the mite and lend evidence to a previous hypothesis that the original host of the mite is a non-coconut palm. In contrast to the diversity in the Americas, all samples from Africa and Asia were identical or very similar, consistent with the hypothesis that the mite invaded these regions recently from a common source. Although the invasion routes of this mite are still only partially reconstructed, the study rules out coconut as the ancestral host of A. guerreronis, thus prompting a reassessment of efforts using quarantine and biological control to check the spread of the pest.

Intergenomic interactions affect female reproduction: evidence from introgression and inbreeding depression in a haplodiploid mite.

Nuclear and cytoplasmic genomes can coevolve antagonistically or harmoniously to affect fitness. One commonly used test for nuclear-cytoplasmic coadaptation relies on the breakup of coadapted gene complexes by introgression, potentially resulting in an increased frequency of nuclear alleles in deleterious interaction with an alien cytoplasm. We investigated the phenotypic effect of such genes on female reproduction in outbred and inbred introgressed lines of the haplodiploid mite Tetranychus urticae. Introgression changed female lifetime fecundity and increased male production, in ways suggesting a control of fecundity by nuclear genes. Conversely introgression reduced the fertilization rate, possibly due to sperm-egg incompatibility or maternal effects. The intensity of inbreeding depression expressed as a reduction in fecundity was more severe in introgressed females than in nonintrogressed ones, giving evidence for recessive interacting alleles contributing to residual nucleo-cytoplasmic incompatibility. Overall, our data suggest recessive negative interactions between nuclear and cytoplasmic genes. This study is the first report of a contribution of nuclear polymorphism within a population to deleterious interactions with an alien cytoplasmic genome.

Raynaud's phenomenon and antiphospholipid antibodies in systemic lupus erythematosus: is there an association?

OBJECTIVE: To evaluate the association of IgG and IgM antibodies directed against different negatively charged phospholipids (that is, anticardiolipin (aCL), antiphosphatidylinositol, antiphosphatidylserine, and antiphosphatidic acid) and anti-beta(2)-glycoprotein I (abeta(2)GPI), with Raynaud's phenomenon in patients with systemic lupus erythematosus (SLE). METHODS: Ninety three patients with SLE (81 female), 40 with and 53 without Raynaud's phenomenon, were included in the study. IgG and IgM antiphospholipid antibodies and abeta(2)GPI were determined by enzyme linked immunosorbent assay (ELISA). RESULTS: Fifty patients (54%) were positive for IgG and/or IgM antibodies to one or more phospholipid antigens or to beta(2)GPI. The prevalence of all autoantibodies evaluated, either IgG or IgM, was higher in patients without than in those with Raynaud's phenomenon. A negative association was found between IgG aCL and Raynaud's phenomenon (p=0.038), whereas autoantibodies other than aCL were not significantly associated with Raynaud's phenomenon. CONCLUSION: Our results demonstrate no positive association between antiphospholipid antibodies and Raynaud's phenomenon in SLE and indicate that measurement of anti-negatively charged phospholipid antibodies other than aCL is not useful as a serological marker predictive for Raynaud's phenomenon.

Nuclear ribosomal DNA monophyly versus mitochondrial DNA polyphyly in two closely related mite species: the influence of life history and molecular drive.

In two very closely related but reproductively isolated mite species, Tetranychus urticae and T. turkestani, we found nucleotide diversity to be extensive for mitochondrial DNA (mtDNA) cytochrome oxidase 1 (COI) (3-4%) but extremely reduced for nuclear ribosomal DNA (rDNA) internal transcribed spacer (ITS2) (less than 0.5%). By contrast, ITS2 was shown to evolve much faster than COI between species of this genus. Furthermore, we found that these two species are polyphyletic for mtDNA but monophyletic for rDNA. Thus it appears that despite its biparental transmission and multiplicity of copies in the genome, nuclear rDNA has a smaller effective population size than mtDNA in these species. The conjunction of efficient concerted evolution and/or gene conversion in the rDNA cluster, the haplodiploidy of these species and their female-biased sex ratio could account for this apparent contradiction.

Phylogenetic relationships in rhinonyssid mites (Acari: Rhinonyssidae) based on ribosomal DNA sequences: insights for the discrimination of closely related species.

The complete internal transcribed spacer 1 (ITS1), 5.8S rDNA and ITS2 region of the ribosomal DNA from 11 species of rhinonyssid mites ( Tinaminyssus columbae, T. minisetosum, T. sartbaevi, T. bubulci, T. melloi, T. streptopelioides, Sternostoma fulicae, S. boydi, S. strandtmanni, S. turdi, Rhinonyssus tringae) were sequenced to assess the utility of this genomic region in resolving taxonomic questions in this group and to estimate phylogenetic relationships between species. Two different geographic locations of T. melloi and T. streptopelioides were analyzed to detect intraspecies variation. Our study shows that ribosomal sequences can help to discriminate between T. melloi and T. sartbaevi, which are morphologically very close and difficult to separate by classic methods. The resulting phylogenetic tree shows some differences from the current taxonomy of the family Rhinonyssidae. This study appeals for the revision of the taxonomic status of S. boydi and closely related species which parasitize aquatic birds and suggests the synonymy of S. boydi and S. strandtmanni, despite the different hosts of the two mites.

Genetic structure of a greenhouse population of the spider mite Tetranychus urticae: spatio-temporal analysis with microsatellite markers.

The genetic structure of a greenhouse population of the mite Tetranychus urticae was studied by the analysis of five microsatellite loci. Genetic variation was compared during a crop season between periods of population foundation and rapid population increase and was investigated in two consecutive years. The population displayed significant heterozygote deficiency at all the sampling periods. However, inbreeding tended to decrease with increasing density (FIS coefficient between 0.13 and 0.25). No significant genetic differentiation between samples was found either at a spatial scale within the greenhouse or at a temporal scale between two growing seasons (FST between 0.008 and 0.09). Estimations of the genetic relatedness between pairs of individuals indicated that the distances between pairs of sisters and unrelated mites in the greenhouse were not significantly different, suggesting that mites do not tend to form patches that reside close to the point of birth.

Mechanisms of resistance to organophosphates in Tetranychus urticae (Acari: Tetranychidae) from Greece.

We investigated the mechanisms conferring resistance to methyl-parathion (44-fold) and to methomyl (8-fold) in Tetranychus urticae from Greece by studying the effect of synergists on the resistance and the kinetic characteristics of various enzymes in a resistant strain (RLAB) and a susceptible reference strain (SAMB). It is shown that S,S,S-tributyl phosphorotrithioate, a synergist that inhibits esterases and glutathione S-transferases, and piperonyl butoxide, a synergist that inhibits cytochrome P450 mediated monooxygenases, did not affect the level of methyl-parathion or methomyl resistance in RLAB and that resistance ratios to both insecticides did not change significantly in the presence of either synergist. Isoelectric focusing of esterase allozymes on single mites revealed no differences in staining intensity and glutathione S-transferase activity was not significantly different in the two strains. The activity of two cytochrome P450 monooxygenase groups was compared. No significant difference of 7-ethoxyresorufin-O-diethylase activity was observed between strains that were two-fold higher in RLAB than in SAMB. The kinetic characteristics of acetylcholinesterase, the target enzyme of organophosphates and carbamates, revealed that acetylcholinesterase in RLAB was less sensitive to inhibition by paraoxon and methomyl in comparison with SAMB. I(50), the inhibitor concentration inducing 50% decrease of acetylcholinesterase activity was greater (119- and 50-fold with paraoxon and methomyl, respectively) and the bimolecular constant k(i) was lower (39- and 47-fold with paraoxon and methomyl, respectively) in RLAB compared to SAMB.