Evidence of environmental effects on reproductive characteristics of Nile tilipia (Oreochromis niloticus) populations from man-made lakes of Ivory Coast

La comparaison des caractéristiques de reproduction des femelles #Oreochromis niloticus$ dans neuf petits barrages de Côte-d'Ivoire a révélé d'importantes différences entre les populations. Ces différences pouvaient être dues à une adaptation rapide des poissons à leur environnement ou à un processus évolutif plus long. Afin de le vérifier, des poissons de deux des populations présentant les paramètres de reproduction les plus différents ont été capturés vivants et placés dans un environnement commun en situation d'élevage. L'analyse génétique des poissons des deux populations, réalisée en utilisant quatre marqueurs microsatellites, a révélé qu'ils étaient issus d'une même souche ("souche Bouaké"), constituée à partir de géniteurs provenant des bassins du Nil et de la Volta. Après avoir partagé un environnement commun (étang ou aquarium) pendant 5 mois, la fécondité, le poids ovocytaire moyen et la fréquence de ponte des femelles des deux populations, qui étaient significativement différents dans leurs milieux respectifs, ne différaient plus. Ces résultats indiquent que les différences de reproduction observées en milieu naturel entre les deux populations sont principalement le fait de la plasticité phénotypique de l'espèce face à des conditions environnementales différentes. (Résumé d'auteur

Kavalactones and flavokavins profiles contribute to quality assessment of kava (Piper methysticum G. Forst.), the Traditional beverage of the Pacific

Kava (Piper methysticum) is increasingly traded internationally and there is need for a rapid method to analyze kava raw material before export. The objectives of the present study were: (i) to develop a simple and robust protocol for high throughput simultaneous quantification of kavalactones (KLs) and flavokavins (FKs) in kava and (ii) to assess its potential for quality control. Methysticin; dihydromethysticin; kavain; desmethoxyyangonin; dihydrokavain; yangonin; and flavokavin A, B and C were quantified using HPTLC in acetonic extracts of 174 kava varieties. UHPLC analysis was conducted on a subset of six varieties representing the genetic variation of the species. The genetically distinct groups of nobles, two-day and wichmannii varieties were clearly differentiated and multivariate analyses of UHPLC and HPTLC data were congruent. Noble varieties have significantly low FKs/KLs (0.13) and high kavain/flavokavin B (K/FKB = 7.31). Two-day and wichmannii varieties are characterized by high FKs/KLs (0.36, 0.21) and low K/FKB (1.5, 1.7). A high-throughput HPTLC protocol was developed with a total analytical time of 50 min for 20 samples and only 10 mL of mobile phase. The use of acetone, sonication and two different detection wavelengths improves the accuracy compared to previous HPLC studies and confirms that kava varieties exhibit distinct chemotypes clearly differentiated by their FKs/KLs profiles. These results will strengthen the use of Codex Alimentarius regional standards

Biology and culture of the clown loach Chromobotia macracanthus (Cypriniformes, Cobitidae) : 1- Hormonal induced breeding, unusual latency response and egg production in two populations from Sumatra and Borneo Islands

The clown loach Chromobotia macracanthus, endemic to Indonesia, is a major species on the international market of ornamental freshwater fish. In order to satisfy an increasing demand with a sustainable alternative to the massive capture of wild juveniles, research has been dedicated to the artificial propagation and domestication of this species. The present study, the first of a series, focused on favourable maintenance conditions for broodfish sexual maturation, criteria for identification of ripe fish, efficiency of hormone-induced breeding treatments, predictability of their latency response, and on the comparison of reproductive performances of fish from populations of Sumatra and Borneo Islands (in total, 112 females of 46 to 404 g body weight). When reared in fully controlled conditions in large water recirculation systems, broodfish originating from Sumatra had reproductive performances similar to or slightly higher than those maturing in the wild (ovulation rate of 93% vs. 82%, relative fecundity of 109 277 vs. 103 550 ova kg(-1) and fertilization rate of 73% vs. 61%, respectively). In the same rearing conditions, captive females from Borneo (n = 22) showed lower ovulation rate (77%), relative fecundity (76 262 ova kg(-1)) and fertilization rate (50%) than those originating from Sumatra (n = 28). By contrast, the mean individual weight of ova (around 0.8 mg) was independent from the origin or maintenance conditions of females. An initial modal follicle diameter >= 1.02 mm generally led to high ovulation success (>80%) after hormonal treatment and is recommended as the main criterion for selecting female broodfish. Two hormonal treatments for inducing oocyte maturation and ovulation (T1: two successive injections of Ovaprim at a 6 h-interval; T2: one injection of human chorionic gonadotropin (hCG)-and one of Ovaprim 24 h later), produced similar results in terms of ovulation rate, quantity and quality of ova collected. With both treatments, the latency decreased with increasing water temperature, then increased again at temperatures >28-29 degrees C. To our knowledge, such U-shaped relationship between the latency response and temperature has never been documented in teleost fishes

Із зали засідань Президії НАН України (26 березня 2014 року)

На черговому засіданні Президії НАН України заслухали такі питання: • створення нових людино-комп’ютерних інтерфейсів для текстової, голосової та жестової форм комунікації (доповідач — доктор фізико-математичних наук Ю.В. Крак); • план заходів з реалізації Концепції розвитку НАН України на 2014— 2023 рр. (доповідач — академік НАН України А.Г. Наумовець); • про наукову та науково- організаційну діяльність Інституту прикладної фізики НАН України (доповідач — академік НАН України І.М. Неклюдов); • про нагородження відзнаками НАН України та Почесними грамотами НАН України і Центрального комітету профспілки працівників НАН України (доповідач — академік НАН України А.Г. Загородній); • кадрові та поточні питання

Biology and culture of the clown loach Chromobotia macracanthus (Cypriniformes, Cobitidae) : 4- Thermal biology of embryos and larvae

The knowledge of how fish survive and grow at different temperatures, and how these traits vary between life stages, is essential to evaluate the effects of climate change on wild fish and implement effective strategies in aquaculture. These issues are addressed in this study through a series of experiments that evaluate the effect of temperature (23-34 degrees C) on the embryos and larvae of clown loach, Chromobotia macracanthus. This species is endemic to the rivers of Sumatra and Borneo, highly praised on the ornamental fish market, and has been reproduced in captivity recently. No embryo survived a 24-h exposure to 34 degrees C until the age of 3 days after hatching (dah); mortality was high at 32 degrees C at 2 and 3 dah, whereas it was low and similar from 1 to 4 dah at 23-29 degrees C (<10%). Yolk absorption was proportional to water temperature (Q(10 degrees C) of 1.69 in the 23-32 degrees C range), but fish reared at cold temperatures were larger than others at the start of exogenous feeding (5.7 vs. 5.5 mm TL, at 23 and 32 degrees C, respectively). The survival of larvae fed Artemia nauplii ad libitum was high at 23-32 degrees C (80-100%), but almost null at 34 degrees C. Growth models at different temperatures were produced from weekly measurements in two experiments, and tested by comparing their predictions with the results of a third experiment. Throughout the larval stage, the optimal temperature for growth (T. opt) was close to 29 degrees C, and departures from T. opt resulted in substantial growth penalties (-30% SGR for -5.1 degrees C and +3.1 degrees C). High survival, fast growth (0.7 mm day(-1)) and limited size dispersal at T. opt are encouraging perspectives for the aquaculture of clown loach. From an ecological perspective, the species has an atypical thermal biology, as it is less thermophilic than other tropical fishes, but more stenothermal than temperate fishes exhibiting similar values of T. opt, both traits being of particular concern in the context of global warming