Effet du lindane sur la croissance pondérale d'Asellus aquaticus L. (crustacé, isopode) en laboratoire et en mésocosme

La croissance pondérale estimée par le taux instantané de croissance (b) d'Asellus aquaticus L. a été évaluée dans des conditions de laboratoire et en milieu naturel dans des mésocosmes. L'influence d'une contamination par du lindane (insecticide organochloré) a été étudiée. Au laboratoire, la durée d'exposition au lindane a été de 20 jours, sa concentration de 4 µg.l-1 au départ était de l'ordre de 2 µg.l-1 à la fin de la période d'exposition : la température a été constante (15 °C) et la photopériode 12/12 heures. Dans les mésocosmes, l'expérimentation a duré du mois de juin au mois de février. Au départ, la concentration du lindane était de 4,5 µg.l-1, elle était voisine de zéro en février. On constate que le taux instantané de croissance (b) est plus élevé dans les mésocosmes qu'au laboratoire, en milieu contaminé qu'en milieu témoin. Dans les conditions de laboratoire il est environ 2,6 lois plus élevé pour des aselles contaminées (de poids compris entre 7 et 12 mg) que pour les aselles témoins. Cette augmentation est significative de l'action du lindane. Dans les mésocosmes, l'augmentation du taux instantané de croissance des aselles maintenues en milieu contaminé par rapport à celles provenant de milieu non contaminé n'est statistiquement significative qu'au septième mois après le début de la contamination par le lindane, elle ne l'est plus au huitième. Il semble que d'autres facteurs puissent expliquer cette augmentation, en particulier la qualité de l'alimentation est discutée. Aussi ne peut-on affirmer que le lindane dans les conditions naturelles est responsable d'une élévation du taux instantané de croissance de l'aselle.We estimated the ponderal growth (instantaneous growth rate) of a fresh-water invertebrate Asellus aquaticus L. (Crustacea, isopoda), bred under laboratory conditions and in experimental mesocosms. Contamination by the insecticide lindane (Pepro 99 % purity) was studied.To estimate the instantaneous growth rate we used the formula Wt = Wo exp Mt) in what Wo is the median weight class of Asellus at the beginning of experiment. Wt is the median weight after 20 days, dj is the days number multiplied by median temperature above 3 °C of considered period (3 °C is considered as minimal temperature below that no development is possible). Seven classe were constituted : class 1 (2 mg to 6.99 mg), 2 (7 to 11.99), 3 (12 to 16.99), 4 (17 to 21.99), 5 (22 to 26.99), 6 (27 to 31.99) and 7 (32 to 36.99). The instantaneous growth rate is calculated for this seven class weight and for each replicate, next median and standard error were calculated for each class. The number of replicate vary among class weight. It was : 22, 33, 29, 22, 16, 15 and 13 respectively for class 1, 2, 3, 4, 5, 6 and 7.Asellus were preleved in natural ponds, acclimated in laboratory conditions during a minimal period of 15 days before that they are used for experiment. (glass containers of 30 litres, filled with hall tap-water hall pond-water, feed with maple leaves).In laboratory conditions Asellus were kept in glass aquarium (15 x 20 x 18 cm) filled with 2 litres of water.Physico-chemical parameters of water were : pH = 8.2; total hardness =155 mg 1-1 measured as Ca C03; nitrites = 0.055 mg 1-1; nitrates = 3 mg 1-1; chloride = 73 mg l-1 as Na C1. Laboratory breeding conditions were a tempera-tare of 15 °C and a 12/12 hours photoperiod. Contamination tasted 20 days, lindane concentration was 4,5 µg. l-1 (near the median lethal concentration, 48 hours : 5.14 µg.1-1) at the beginning of the experiment and approximatively 2 µg.1-1 at the end. Twenty Asellus of the same weight class were deposed in each glass. The diet was constitued with maple leaves. For contamination study only Asellus of class 7 to 11.99 was study. Ten replicates were realised.The mesocosms were constituted by two rectangular basins 10 meters in length, 2.5 m in width and 50 to 60 cm in deep. To secure a good water-thightness, bottom and sides were covered with black polyane 150 µm in thick, sediment and sand were deposed on the bottom on 5 to 10 cm in thick. Next basins were gradually (July 1987 to January 1988) filled up with tapwater. Natural colonization by phytoplankton and insects were observed, whereas vegetable (Ranunculus aquatilis, Typha angustifolia, Scirpus palustris and Ceratophyllum submersum) and invertebrates (Asellus, Planaria and Leech) were introduced by us. One mesocosm was contaminated by surface spraying with lindane acetonic solution.Thirty of a same weight class were placed in 25 x 12 x 7 cm plastic box, with a total of 20 lateral openings on either side (1.2 cm in diameter) disposed in two rows and covered with fine mesh net (150 µm in opening). The center part of the lid was cut out and also covered with the same fine mesh net. A bed of maple leaves was placed on the bottom of the box. This containers were then distributed throughout bath the control and lindane contaminated basins. Between 15 to 20 days later, this containers were collected and brought back to the laboratory. All the specimens were weighted and once divided into size classes and returned to their experimental basins. The experiment started in June 1988 and lasted till February 1989. The lindane concentration was 4.5 µg.l-1 at the beginning and near zero at the end.For the control, in laboratory condition or in mesocosm, we observed that the instantaneous growth rate decrease when the median weight of the class increase. It vary to 0.1131 mg.mg- 1.dj-1 to 0.0183 mg.mg-1.dj-1 and to 0.2704 mg.mg-1.dj-1 to 0.0879 mg.mg-1.dj-1 respectively in laboratory condition and mesocosm. Significant correlation (level 0.001) was observed between the logarithm of instantaneous growth rate and logarithm of the weight. Slope of regression lines does not vary, only position differ. Growth rate was higher in the mesocosm than in laboratory. In laboratory conditions lindane contamination induce a variation of instantaneous growth rate. An significant increase of 2.6 was observed between contaminated and control for Asellus of weight class 7 to 11.99 mg. In the contaminated mesocosm, a correlation is noted between instantaneous growth rate and weight, it is significant only for 3 collections dates (December 1988, January 1989 and February 1989). No variation in the slope of linear regression is noted, position differ significatively (level 0.01) only in February. For this collection date instantaneous growth rate is higher in contaminated mesocosm than in control. It appear that other factors that lindane contamination may also explain this increase. Among these, food quality has been envisaged by different authors. In conclusion is noted that in laboratory condition lindane induce an increase of instantaneous growth rate, in mesocosm we can't affirm that lindane was the responsible for the increase of instantaneous growth rate. Other experiments are necessary to confirm this observation

Effect of high temperature on the production of 2n pollen grains in diploid roses and obtaining tetraploids via unilateral polyploidization

To integrate the gene pool of a wild species (primarily diploid) into a cultivated pool (primarily tetraploid), a crossing between a dihaploid cultivated rose and a hybrid of Rosa wichurana allowed to obtain interspecific diploid hybrids that produced 2n pollen grains. A return to a tetraploid level sought by breeders can then be considered using sexual polyploidization, obtained by crossing a tetraploid cultivated rose with these hybrids. Application of a high-temperature regime led to a small but significant increase in the percentage of 2n pollen grains in these hybrids of up to 4.6%. This result was obtained by applying high temperatures close to 32°C during the day to plants cultivated in a glasshouse during recurrent cycles of bloom. Crosses were made between an unreleased tetraploid hybrid tea rose, as a female, and the diploid hybrid that produces the most 2n pollen grains. Tetraploid (42.1%) and triploid (57.9%) offspring were obtained. The use of these 2n pollen grains of the first division restitution type should facilitate the introgression of complex traits of interest

Thermal Properties of Heavy Fermion Compound YbP

Low-temperature specific heat and its field-dependence up to 16 T was measured in a stoichiometric single crystal of YbP. A sharp peak was observed at {\it T}$_{\rm N}$ = 0.53 K in zero magnetic field. Application of external field seems to induce a new magnetic phase above 11 T. The field dependence of the transition temperature in the high-field phase is different from that of the low field phase. The linear coefficient of the electronic specific heat is estimated as 120 mJ/mole K$^{2}$ from low temperature specfic heat, suggesting heavy Fermion state in YbP.Comment: to be published in J.Phys.Soc.Jpn on May, 200

Transport of charged particles by adjusting rf voltage amplitudes

We propose a planar architecture for scalable quantum information processing (QIP) that includes X-junctions through which particles can move without micromotion. This is achieved by adjusting radio frequency (rf) amplitudes to move an rf null along the legs of the junction. We provide a proof-of-principle by transporting dust particles in three dimensions via adjustable rf potentials in a 3D trap. For the proposed planar architecture, we use regularization techniques to obtain amplitude settings that guarantee smooth transport through the X-junction.Comment: 16 pages, 10 figure

Failure of the empirical OCT law in the Bi2Sr2CuO6+d compound

We have studied the evolution of the thermoelectric power S(T) with oxygen doping of single-layered Bi2Sr2CuO6+d thin films and ceramics in the overall superconducting (Tc, S290K) phase diagram. While the universal relation between the room-temperature thermopower S290K and the critical temperature is found to hold in the strongly overdoped region (d>0.14), a strong violation is observed in the underdoped part of the phase diagram. The observed behaviour is compared with other cuprates and the different scenarios are discussed.Comment: 7 pages, 5 figure

How much Arctic fresh water participates in the subpolar overturning circulation?

Fresh Arctic waters flowing into the Atlantic are thought to have two primary fates. They may be mixed into the deep ocean as part of the overturning circulation, or flow alongside regions of deep water formation without impacting overturning. Climate models suggest that as increasing amounts of fresh water enter the Atlantic, the overturning circulation will be disrupted, yet we lack an understanding of how much fresh water is mixed into the overturning circulation’s deep limb in the present day. To constrain these fresh water pathways, we build steady-state volume, salt, and heat budgets east of Greenland that are initialized with observations and closed using inverse methods. Fresh water sources are split into oceanic Polar Waters from the Arctic and surface fresh water fluxes, which include net precipitation, runoff, and ice melt, to examine how they imprint the circulation differently. We find that 65 mSv of the total 110 mSv of surface fresh water fluxes that enter our domain participate in the overturning circulation, as do 0.6 Sv of the total 1.2 Sv of Polar Waters that flow through Fram Strait. Based on these results, we hypothesize that the overturning circulation is more sensitive to future changes in Arctic fresh water outflow and precipitation, while Greenland runoff and iceberg melt are more likely to stay along the coast of Greenland

Thermopower in the strongly overdoped region of single-layer Bi2Sr2CuO6+d superconductor

The evolution of the thermoelectric power S(T) with doping, p, of single-layer Bi2Sr2CuO6+d ceramics in the strongly overdoped region is studied in detail. Analysis in term of drag and diffusion contributions indicates a departure of the diffusion from the T-linear metallic behavior. This effect is increased in the strongly overdoped range (p~0.2-0.28) and should reflect the proximity of some topological change.Comment: 4 pages, 4 figure

Fostering innovation in the blue economy within the United Kingdom (UK): A stakeholders’ perspective

In a 2019 European Commission report, the Blue Economy (BE) within the United Kingdom (UK) represented 22% of the European Union's (EU) BE Gross Value Added (GVA) at approximately €39 billion. Coupled with the clear value of the BE to the UK, there is an urgent need to innovate and develop technologies to decarbonise and advance the sector. A deeper understanding of the current position for multiple stakeholders must be considered before any major governmental or long-term strategy decisions can be made. This paper presents the perspective of academic, industrial and governmental stakeholders analysis of how the UK can move forward with developing innovations within the BE. Utilising a questionnaire and round table discussions, specialists from all stakeholders gave their opinions on industry-academia-governmental working relationships and technology transfer readiness. Reasonably high satisfaction was found with key aspects that enable a successful collaborative project between academia and industry towards technology commercialisation; however, there is still room for improvement. This paper offers an analysis of how to further enhance and foster technology development within the UK BE. A collaborative approach is proposed to ensure best practices, and a ‘triple helix’ (TH) collaboration strategy to be used as a tool for those engaging in these types of working relationships. Future directions on enhancing technology transfer innovation within the UK BE are also suggested