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International audience; We investigated the mating and fertilization patterns in one Czech local population of the invasive aphidophagous ladybird Harmonia axyridis (Pallas), sampling the same mixed generations before and after overwintering. Our study using eight microsatellite loci provides the first direct evidence that females of H. axyridis are highly polyandrous in the wild and that they not only mate multiple times but also use the sperm from multiple males to fertilize their eggs. Three types of values (minimum number of fathers, estimated number of fathers and effective number of fathers contributing to progeny of one mother) were about two times higher in the spring sample (2.9, 5.2, 3.1), in the peak of their reproduction period, than in the preceding autumn sample (1.6, 2.8, 1.6). The contribution of individual fathers to the number of progeny was highly unbalanced, with a few dominating fathers and many fathers with low number of progeny.

International audience; We investigated factors which may determine realised paternity following multiple mating in a promiscuous ladybird Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), namely the mating order and ability of males of different morphs to fertilize females. In experiments using males of two colour morphs, we found that the first male had a reproductive advantage over the second male (sperm precedence P2 = 0.38). Males of the melanic morph spectabilis had a reproductive advantage over males of the semi-melanic morph axyridis (P2 = 0.35). Analysis of paternity using microsatellites applied to young larvae, which avoids possible differential mortality of progeny, confirmed the precedence of the first male and higher paternity rate of colour morphs that are more frequent in the wild. Hatchability of eggs increased from 65% after the first mating to 85% after the second mating delayed by five days. Average duration of mating was 157 min and did not differ between the first and second mating and between the colour morphs of males.

Understanding biological invasion is currently one of the main scientific challenges for ecologists. The introduction process is crucial for the success of an invasion, especially when it involves a demographic bottleneck. A small introduced population is expected to face a higher risk of extinction before the first stage of invasion is complete if inbreeding depression, caused by the expression of deleterious alleles, is important. Changes in mating regimes or in population size can induce the evolution of deleterious allele frequencies, either by selection or by drift, possibly resulting in the purging or the fixation of such alleles within the population. The harlequin ladybird Harmonia axyridis became invasive on several continents following a scenario including at least one event of demographic bottleneck. Although native populations suffered from severe inbreeding depression, it was greatly reduced in invasive ones suggesting that deleterious alleles were purged during the invasion process. In this study, we performed an experiment designed to manipulate the effective population size of H. axyridis across successive generations to mimic contrasting introduction events. We used the measurement of two fitness-related phenotypic traits in order to test (1) if inbreeding depression can evolve at the time-scale of an invasion; and (2) if the changes in inbreeding depression following a bottleneck in laboratory conditions are compatible with the purging of deleterious alleles observed in this species. We found that two generations of very low population size are enough to induce a substantial change in inbreeding depression. Although the genetic changes mostly consisted in fixation of deleterious alleles, purging did also occur, sometimes simultaneously with fixation.

The grain-size dependence of impedance spectra of electroceramics is simulated, based on a brick layer model with explicit consideration of parallel boundaries. A constant grain interior conductivity is assumed and the grain boundary (gb) conductivity is varied. Parallel and series gb are assumed isotropic, i.e. charge transport along and across gb is supposed identical. Various grain sizes between 500 and 0.5 nm are studied and impedance spectra are shown in complex plane and Bode representations.

Reproductive strategy affects population dynamics and genetic parameters that can, in turn, affect evolutionary processes during the course of biological invasion. Life-history traits associated with reproductive strategy are therefore potentially good candidates for rapid evolutionary shifts during invasions. In a series of mating trials, we examined mixed groups of four males from invasive and native populations of the harlequin ladybird Harmonia axyridis mating freely during 48 hours with one female of either type. We recorded the identity of the first male to copulate and after the 48 h-period, we examined female fecundity and share of paternity, using molecular markers. We found that invasive populations have a different profile of male and female reproductive output. Males from invasive populations are more likely to mate first and gain a higher proportion of offspring with both invasive and native females. Females from invasive populations reproduce sooner, lay more eggs, and have offspring sired by a larger number of fathers than females from native populations. We found no evidence of direct inbreeding avoidance behaviour in both invasive and native females. This study highlights the importance of investigating evolutionary changes in reproductive strategy and associated traits during biological invasions.

Impedance spectra (IS) of a polycrystalline sample with macroscopic dimensions are analyzed based on the brick layer model with parallel and series grain boundaries (gb). The gb width is taken as 0.5 nm, in accordance with the classical Fisher model of gb diffusion. Three mean grain size values of 500, 50, and 5 nm are simulated, corresponding to a change from microcrystalline to nanocrystalline ceramics. A constant conductivity of the grain interior (10 - 3 S/m) and of the series gb (10 - 6 S/m) is assumed. Impedance spectra are simulated for parallel gb conductivity values between 10 - 6 (blocking) and 10 - 1 S/m (conductingl. Two impedance arcs are observed in all cases, but the conventional attribution of the high-frequency arc to the grain interior and the low-frequency semicircle to the series gb is valid only when the parallel gb contribution is insignificant, i.e., for low parallel gb conductivity and/or large mean grain size.

The authors present an accurate determination of the percolation transport exponent u=t/(s+t) in three dimensions, based on a transfer-matrix approach to the AC (frequency-dependent) conductivity, and a finite-size scaling analysis of the numerical data. The phase of the complex conductivity, the loss angle, assumes the universal value delta c=( pi /2)(1-u) at low frequency at the percolation threshold. As a test of their numerical scheme, the two-dimensional exact duality result delta c= pi /4 (i.e. s=t) is recovered with a very good accuracy. In three dimensions, their data are extrapolated to tan delta c=0.54+or-0.03, i.e. u=0.69+or-0.02, whereas the usually accepted values s/v=0.85+or-0.04, t/v=2.2+or-0.1 yield u=0.72+or-0.02. This marginal disagreement can be attributed to ill behaved corrections to finite-size scaling.

A testing-stand is described which allowed us to measure noises on a fractal lattice built with resistors and capacitors. Flicker noise measures of resistors taken one by one show a great dispersion. In this lattice, for size dependence, the exponent measured value is in keeping with calculations and included between theoretical bounds.

Saudubray, J. M., Cathelineau, L., Laugier, J. M., Charpentier, C, Lejeune, J. A. and Mozzionacci, P. (Clinique Medicale Infantile, Hopital des Enfants-Malades, Paris, Laboratoire du Pr. C. Polonovski, Hopital Trousseau, Paris, and Laboratoire du Pr. Lemonnier, Hopital du Kremlin-Bicetre, Le Kremlin-Bicetre, France). Hereditary ornithine trans-carbamjlast deficiency. Report of two male cases with residual enzymatic activity. Acta Paediatr Scand, 64:464, 1975.–The authors report two male cases of liver ornithine carbarn} 1 transferase deficiency. In one the disease occurred at 8 years of age with hyperam-moniemic coma leading to death in 48 hours. In the second case, symptoms appeared on the sixth day of life but the outcome was favorable. The child is normal at 15 months. In both cases, there was a residual 6–10 % OCT activity. These observations are similar to two other male cases in the literature and are different from the male neonatal fatal form in which the deficiency is virtually total. They underline the genetically heterogeneous nature of OCT deficiencies and the fact that in this X-Iransmitted trait, hemizygotes can preserve a functional enzymatic activity compatible with life.