Bionomies comparées de deux souches (Marocaine et Américaine) d’Ooencyrtus kuvanae [Hym.: Encyrtidae], parasite oophage deLymantria dispar [Lep.: Lymantriidae]

Résumé Des adultes d’Ooencyrtus kuvanae (Howard) sortis d’œufs deLymantria dispar (L.) récoltés au Maroc et aux états-Unis ont été élevés séparément mais simultanément dans les mêmes conditions abiotiques. On a évalué chez ces adultes des caractéristiques bionomiques telles que la longévité, la proportion de ♀ fécondes, la fécondité réelle moyenne, la durée de la période de ponte et le pourcentage d’œufs viables développés par parthénogenèse. Chez la progéniture, on a évalué la survie des larves et la proportion de ♀. Aucune différence significative entre les 2 souches n’est apparue. Des croisements entre les 2 souches ont donné une descendance comportant des proportions équivalentes de ♀.O. kuvanae avait été introduit au Maroc en 1926 depuis les états-Unis. Ainsi, 50 années d’acclimatation de ce parasite au Maroc (soit près de 500 générations) n’ont pas modifié ses potentialités et n’ont pas suffi à induire chez lui une nouvelle race géographique.

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Summary Adults ofOoencyrtus kuvanae (Howard) were recovered from eggs ofLymantria dispar (L.) collected in Morocco and in the U.S.A. They were reared separately and simultaneously under identical laboratory conditions. Various biological characteristics of adults from both sources were compared including longevity, proportion of fertilized versus unfertilized females, fecundity, duration of the oviposition period, and the percentage of viable eggs produced by virgin females. Also the survival of the larvae and the sex ratio of the 2 cultures were evaluated. Crossbreeding individuals of the 2 cultures resulted in a similar proportion of females in the progeny. In general there were no significan differences found between the 2 cultures.O. kuvanae had been introduced in Morocco in 1926 from the U.S.A. The adaptation of this parasite to conditions in Morocco during the ensuring 50 years since its establishment (about 500 generations) did not appear to modify the biotic potential of this species nor was it sufficient to induce the development of a new geographic race.

     

Atrial natriuretic factor messenger ribonucleic acid and peptide in the human heart during ontogenic development

We have investigated the level of expression of the atrial natriuretic factor (ANF) gene in the human heart during ontogenic development by determining the concentrations of ANF messenger ribonucleic acid (ANF mRNA), of immunoreactive ANF (IR ANF) and of receptor reactive ANF (RR ANF), in myocardial samples of the various heart chambers. We found the level was high and almost identical in the left and right ventricles in utero. It gradually decreased during ontogenic development to reach the low adult levels, with a more rapid decrease in the right than in the left ventricle after birth. In the atria, ANF gene expression was high as early as the 13th week of gestation, was higher in the right than in the left atrium, and appeared little affected by ontogenic development.     

Tyrosine kinase and protein kinase C regulate L-type Ca(2+) current cooperatively in human atrial myocytes

The effects of tyrosine protein kinases (TK) on the L-type Ca(2+) current (I(Ca)) were examined in whole cell patch-clamped human atrial myocytes. The TK inhibitors genistein (50 microM), lavendustin A (50 microM), and tyrphostin 23 (50 microM) stimulated I(Ca) by 132 +/- 18% (P < 0.001), 116 +/- 18% (P < 0.05), and 60 +/- 6% (P < 0.001), respectively. After I(Ca) stimulation by genistein, external application of isoproterenol (1 microM) caused an additional increase in I(Ca). Dialyzing the cells with a protein kinase A inhibitor suppressed the effect of isoproterenol on I(Ca) but not that of genistein. Inhibition of protein kinase C (PKC) by pretreatment of cells with 100 nM staurosporine or 100 nM calphostin C prevented the effects of genistein on I(Ca). The PKC activator phorbol 12-myristate 13-acetate (PMA), after an initial stimulation (75 +/- 17%, P < 0.05), decreased I(Ca) (-36 +/- 5%, P < 0.001). Once the inhibitory effect of PMA on I(Ca) had stabilized, genistein strongly stimulated the current (323 +/- 25%, P < 0.05). Pretreating myocytes with genistein reduced the inhibitory effect of PMA on I(Ca). We conclude that, in human atrial myocytes, TK inhibit I(Ca) via a mechanism that involves PKC.     

Duration and spread of an entomopathogenic fungus, Beauveria bassiana (Deuteromycota: Hyphomycetes), used to treat varroa mites (Acari: Varroidae) in honey bee (Hymenoptera: Apidae) hives

A strain of the fungus Beauveria bassiana (Balsamo) Vuillemin (Deuteromycota: Hyphomycetes) isolated from varroa mites, Varroa destructor Anderson & Trueman (Acari: Varroidae), was used to treat honey bees, Apis mellifera L. (Hymenoptera: Apidae), against varroa mites in southern France. Fungal treatment caused a significant increase in the percentage of infected varroa mites compared with control treatments in two field experiments. In the first experiment, hives were treated with a formulation containing 0.37 g of B. bassiana conidia per hive and in the second experiment with a dose of 1.0 g of conidia per hive. The percentage of infected varroa mites also increased in the nontreated (control) hives, suggesting a movement of conidia, probably via bee drift, among the hives. Mite fall was significantly higher among treated hives compared with control hives on the sixth and eighth days after treatment in the first experiment. These days correspond to previously published data on the median survivorship of mites exposed to that fungal solate. The interaction of treatment and date was significant in the second experiment with respect to mite fall. Increases in colony-forming unit (cfu) density per bee were observed in all treatments but were significantly higher among bees from treated hives than control hives for at least a week after treatment. The relationship between cfu density per bee and proportion infected was modeled using a sigmoid curve. High levels of infection (>80%) were observed for cfu density per bee as low as 5 x 102 per bee, but the cfu density in hives treated with 0.37 g generally dropped below this level less than a week after treatment.     

FKBP12.6 mice display temporal gender differences in cardiac Ca(2+)-signalling phenotype upon chronic pressure overload

Preventing Ca(2+)-leak during diastole may provide a means to improve overall cardiac function. The immunosuppressant FK506-binding protein 12.6 (FKBP12.6) regulates ryanodine receptor-2 (RyR2) gating and binds to and inhibits calcineurin (Cn). It is also involved in the pathophysiology of heart failure (HF). Here, we investigated the effects of FKBP12.6 over-expression and gender on Ca(2+)-handling proteins (RyR2, SERCA2a/PLB, and NCX), and on pro-(CaMKII, Cn/NFAT) and anti-hypertrophic (GSK3β) signalling pathways in a thoracic aortic constriction (TAC) mouse model. Wild type mice (WT) and mice over-expressing FKBP12.6 of both genders underwent TAC or sham-operation (Sham). FKBP12.6 over-expression ameliorated post-TAC survival rates in both genders. Over time, FKBP12.6 over-expression reduced the molecular signature of left ventricular hypertrophy (LVH) and the transition to HF (BNP and β-MHC mRNAs) and attenuated Cn/NFAT activation in TAC-males only. The gender difference in pro- and anti-hypertrophic LVH signals was time-dependent: TAC-females exhibited earlier pathological LVH associated with concomitant SERCA2a down-regulation, CaMKII activation, and GSK3β inactivation. Both genotypes showed systolic dysfunction, possibly related to down-regulated RyR2, but only FK-TAC-males exhibited preserved diastolic LV function. Although FKBP12.6 over-expression did not impact the vicious cycle of TAC-induced HF, this study reveals some subtle sequential and temporal gender differences in Ca(2+)-signalling pathways of pathological LVH.     

Degradation of iprodione by a soil Arthrobacter-like strain.

A bacterial strain able to transform iprodione was isolated from a fast iprodione-degrading soil by enrichment procedures. Transformation was detected through 3,5-dichloroaniline production as measured by a rapid colorimetric method. The strain, MA6, was tentatively identified as an Arthrobacter sp. When it was incubated with MA6 in a minimum mineral medium (pH 6.5), iprodione (8.8 mumol/liter) was transformed into two major metabolites that were identified by high-performance liquid chromatography analysis: 3,5-dichlorophenylcarboximide (metabolite 1) and (3,5-dichlorophenylurea) acetic acid (metabolite 2), which was produced after ring cleavage of the former product. These products were synthesized in the laboratory and compared with metabolites 1 and 2 which were formed during iprodione degradation. Small quantities of 3,5-dichloroaniline also appeared in the bacterial culture but did not substantially increase between the first and second days of incubation. In contrast, in the sterile control medium, iprodione was spontaneously transformed into hydantoic acid and an iprodione isomer. Chemical and biological transformations of iprodione seem to occur through two different pathways. One biological degradation pathway is proposed.     

Doppler echocardiographic estimation of left ventricular end-diastolic pressure after MI in rats

The spectral Doppler mitral flow pattern, alone or combined with tissue Doppler mitral annulus velocity, can be used to predict left ventricular (LV) filling pressure in humans, whereas invasive hemodynamic measurements are still required in the rat. This study was undertaken to assess whether LV end-diastolic pressure (LVEDP) can be estimated using Doppler echocardiography in the rat after myocardial infarction (MI). Thirty-seven rats (23 rats with MI after left coronary artery ligation and 14 sham-operated rats) were evaluated 3 mo after surgery with echo-Doppler and invasive hemodynamic measurements. Pulse wave spectral Doppler at the mitral valve tip was used to measure the E wave, the E wave deceleration time (DT), and the A wave; spectral Doppler tissue imaging was used to measure the early diastolic lateral mitral annulus velocity (E(a)). We found weak correlations between LVEDP and the peak velocity of the early mitral inflow (E), E/peak velocity of the late mitral inflow, and DT, and strong correlations with E(a) and especially with E/E(a) [R(2) = 0.89, LVEDP (in mmHg) = 0.987E/E(a) - 4.229]. Longitudinal followup of a subgroup of rats with MI revealed a marked rise of E/E(a) between days 7 and 21 in rats with heart failure only. We conclude that Doppler echocardiography can be used for serial assessment of LV diastolic function in rats with MI.     

Observations onHexamermis albicans [Nematoda: Mermithidae] recovered fromLymantria dispar andStilpnotia salicis [Lep.: Lymantriidae] in west Germany and Austria

The mermithid,Hexamermis albicans (Siebold) was recovered from larvae ofLymantria (Porthetria) dispar (L.) collected from various localities in Burgenland, Austria in 1974 and 1975 and from Würzburg, Germany, in 1974. It was recovered also fromStilpnotia salicis (L.) in Austria in 1974. The mermithid was recovered from all field collected larval instars. The majority of the nematodes emerged fromL. dispar larvae collected as second and third larval instars although some nematodes were recorded from larvae collected as first instar larvae still on the egg mass. Peak emergence occurred in the laboratory during the period June 11–17 of both years, but emergence continued at a much lesser degree through the end of larval development. The nematode was found in both high and low host density populations. In 3 localities studied both years, there was a general increase in the percentage parasitism the second year. However, except for one locality in Austria in 1975 where individual samples produced up to 11% parasitism, the overall parasitism increased from 0.4% in 1974 to only 2.5% in 1975.