Search results for "noi"

The effect of low frequency noise on the behaviour of juvenile Sparus aurata.

2020

[EN] Anthropogenic activities are causing increased noise levels in the marine environment. To date, few studies have been undertaken to investigate the effects of different noise frequencies on the behaviour of juvenile fish. In this study, the behavioural changes of juvenile gilthead seabream (Sparus aurata) are evaluated when exposed to white noise filtered in third-octave bands centred at 63, 125, 500, and 1000 Hz (sound pressure level, 140-150 dB re 1 mu& x3a1;a) for 7 h. The group dispersion, motility, and swimming height of the fish were analysed before and during the acoustic emission. Dispersion of the fish was found to reduce immediately upon application of low frequency sound (63…

Chemical host detection and differential attraction in a parasitic pea crab infecting two echinoids

2011

Mechanisms of host detection and host choice are important for mobile parasites or symbionts that frequently move among host individuals. The parasitic pea crab Dissodactylus primitivus is an ectoparasite exploiting asymmetrically two spatangoid echinoid hosts, Meoma ventricosa and Plagiobrissus grandis. The entire life cycle takes place on M. ventricosa, while only adults colonize P. grandis, the host where female's fecundity is the greatest. Dissodactylus primitivus frequently exhibits host-switching, a behaviour that raises the question of host detection. To test if adult crabs are able to detect potential hosts and are attracted to the host where their fitness is greater, crab olfactory…

GenExP, un logiciel simulateur de paysages agricoles pour l'étude de la diffusion de transgènes

2007

 ; The software GENEXP allows to simulate 2-dimensional agricultural landscapes by using a traditional algorithmic geometry. Based on real or realistic field-patterns, GENEXP provides multiannual maps of agricultural landscapes, which are used by softwares simulating the dispersal of GM pollen grains and seeds at various scales.; GENEXP est un simulateur de paysages agricoles qui engendre des découpages parcellaires en utilisant une géométrie algorithmique classique. GENEXP fournit, sur la base de parcellaires réels ou réalistes, des cartes pluriannuelles de paysages agricoles utilisables par des logiciels qui simulent la dispersion des pollens et des graines d'OGM à différentes échelles.

Male bill colour and age are associated with parental abilities and breeding performance in blackbirds

2005

9 pages; International audience; In monogamous bird species, male parental investment may influence offspring fitness and females may gain advantages through mating with males providing extensive paternal care. However, paternal care is a benefit that can only be assessed indirectly because mate choice precedes paternal activities. Individual quality and age, both signalled by morphological characteristics, may reflect parental abilities. Because they may reflect individual foraging abilities, carotenoid-based colorations have been proposed to honestly signal parental quality. The blackbird (Turdus merula), a socially monogamous species, exhibits biparental care and males show bills that va…

Volatile components of ripe fruits of Morinda citrifolia and their effects on Drosophila

1996

Abstract The only larval resource of the specialist species, Drosophila sechellia , is ripe fruits of Morinda citrifolia . The chemical composition of this fruit, which is very toxic to most Drosophila species, was investigated and 51 compounds were abundant enough to be identified by GC-MS. The ripe fruit is characterized by a large amount of carboxylic acids, especially octanoic and hexanoic acids. The biological effects of the ripe fruit and its main acids were investigated with behavioural studies. Octanoic acid is responsible for the general toxicity of the fruit to most Drosophila species; D. sechellia is the only species which is resistant to this acid. Hexanoic acid has a unique eff…

First record of <em>Arctodiaptomus wierzejskii</em> (Richard, 1888) (Copepoda Calanoida Diaptomidae) from Malta

2020

Diaptomid copepods belonging to the genus Arctodiaptomus Kiefer, 1932 were collected in two temporary water bodies in Malta. The morphological identification of the collected specimens proved that they belong to Arctodiaptomus wierzejskii (Richard, 1888) even if a morphological peculiarity pertaining to the morphology of the male right antennule of the Maltese populations was observed and here briefly discussed. This finding constitutes the first record of a calanoid copepod from the inland waters of the Maltese Islands.

2019

Reptiles use pterin and carotenoid pigments to produce yellow, orange, and red colors. These conspicuous colors serve a diversity of signaling functions, but their molecular basis remains unresolved. Here, we show that the genomes of sympatric color morphs of the European common wall lizard ( Podarcis muralis ), which differ in orange and yellow pigmentation and in their ecology and behavior, are virtually undifferentiated. Genetic differences are restricted to two small regulatory regions near genes associated with pterin [ sepiapterin reductase ( SPR )] and carotenoid [ beta-carotene oxygenase 2 ( BCO2 )] metabolism, demonstrating that a core gene in the housekeeping pathway of pterin bi…

Characterizing the pigment composition of a variable warning signal of Parasemia plantaginis larvae

2010

Summary 1. Aposematic animals advertise their defences to predators via warning signals that often are bright colours combined with black patterns. Predation is assumed to select for large pattern elements and conspicuousness of warning signals because this enhances avoidance learning of predators. However, conspicuousness of the colour pattern can vary among individuals of aposematic species, suggesting that warning signal expression may be constrained by opposing selection pressures. If effective warning signals are costly to produce, variation in signal expression may be maintained via physiological trade-offs. To understand the costs of signalling that might underlay both physiological …

Antioxidant activity and enzymes inhibitory properties of several extracts from two Moroccan Asteraceae species

2018

Abstract The present work reports investigation on phenolic compounds, antioxidant activity and enzyme inhibitory activities (acetylcholinesterase, butyrylcholinesterase, tyrosinase, α-amylase and α-glucosidase) of different extracts from two Moroccan Asteraceae species; Bubonium imbricatum Cav. and Cladanthus arabicus (L.) Cass. B. imbricatum extracts contained the highest amounts of phenolics and flavonoids, and also exhibited higher antioxidant activity. In this species, the highest total phenolic (1611.13 ± 14.23 μmolGAE/gextract) and flavonoid (376.11 ± 8.22 μmolQE/gextract) contents were observed in aqueous-methanol extract obtained by maceration. Further, UHPLC–MS analysis of C. arab…

Fruit and juice characteristics of 30 accessions of two cactus pear species (Opuntia ficus indica and Opuntia megacantha) from different regions of M…

2016

Abstract The fruit and fruit juice of 30 accessions of cactus pear (23 accessions of Opuntia ficus indica and 7 accessions of Opuntia megacantha ) grown in different regions of Morocco were analyzed. The morphological characteristics of the fruit and the pH, titratable acidity, contents of soluble solids, total carotenoids, reducing sugars, and vitamin C in the fruit juice were analyzed. Fruit length, fresh fruit weight, fresh skin weight, fresh skin to fruit ratio, dry skin weight, and water content in the skin varied significantly within and between the two species. There were significant differences among accessions in most of the fruit juice characteristics. The ranges of measured value…