Early weaning of winter flounder (Pseudopleuronectes americanus Walbaum) larvae on a commercial microencapsulated diet

Like most small marine fish larvae, the stomachs of winter flounder Pseudopleuronectes americanus are undeveloped at first feeding and have relatively reduced digestive capacity. This work was undertaken to test whether larvae at the onset of stomach differentiation (larval size about 5.5 mm) could be early weaned onto a commercial microencapsulated diet. We assessed the effect of early weaning by first comparing growth performance (standard length, total protein content and age at metamorphosis) of larvae fed enriched live prey from first feeding to a size of 5.5 mm and then reared on three different feeding regimes until metamorphosis: (1) live prey (LP) as a control group; (2) mixed feeding of live prey and microencapsulated diet (LP‐ME); (3) exclusively microencapsulated diet (ME) after fast weaning over 4 days (to a larval size of 6.2 mm). No differences were observed between larval development in the two first groups, which began metamorphosis at 40 days old. The larvae of the third group showed significantly slower growth that resulted in a delay of 4 days in the onset of metamorphosis. Differences in live prey availability between the treatments and the short transition period to allow the larvae to adapt to the new diet were identified as possible contributing factors to the slower growth and to the delay in metamorphosis of early weaned larvae. In a second experiment, the transitional weaning period was increased until the larvae were 6.6 mm in length. Weaning at that size resulted in no slowing of growth or delay in metamorphosis, suggesting that the feeding schedule was adequate.     

Hyoscine‐N‐butylbromide premedication on cardiovascular variables of horses sedated with medetomidine

ObjectiveTo evaluate the effects of intravenous (IV) or intramuscular (IM) hyoscine premedication on physiologic variables following IV administration of medetomidine in horses.Study designRandomized, crossover experimental study.AnimalsEight healthy crossbred horses weighing 330 ± 39 kg and aged 7 ± 4 years.MethodsBaseline measurements of heart rate (HR), cardiac index (CI), respiratory rate, systemic vascular resistance (SVR), percentage of patients with second degree atrioventricular (2^oAV) block, mean arterial pressure (MAP), pH, and arterial partial pressures of carbon dioxide (PaCO₂) and oxygen (PaO₂) were obtained 5 minutes before administration of IV hyoscine (0.14 mg kg^?1; group HIV), IM hyoscine (0.3 mg kg^?1; group HIM), or an equal volume of physiologic saline IV (group C). Five minutes later, medetomidine (7.5 μg kg^?1) was administered IV and measurements were recorded at various time points for 130 minutes.ResultsMedetomidine induced bradycardia, 2^oAV blocks and increased SVR immediately after administration, without significant changes in CI or MAP in C. Hyoscine administration induced tachycardia and hypertension, and decreased the percentage of 2^oAV blocks induced by medetomidine. Peak HR and MAP were higher in HIV than HIM at 88 ± 18 beats minute^?1 and 241 ± 37 mmHg versus 65 ± 16 beats minute^?1 and 192 ± 38 mmHg, respectively. CI was increased significantly in HIV (p ≤ 0.05). Respiratory rate decreased significantly in all groups during the recording period. pH, PaCO₂ and PaO₂ were not significantly changed by administration of medetomidine with or without hyoscine.Conclusion and clinical relevanceHyoscine administered IV or IM before medetomidine in horses resulted in tachycardia and hypertension under the conditions of this study. The significance of these changes, and responses to other dose rates, requires further investigation.     

Growth of Daphnia magna on urban wastewaters tertiarily treated with Scenedesmus sp.

The productivity and composition of Daphnia magna were measured for high density populations grown in 5-litre flow-through tanks supplied with a tertiary effluent. This effluent was urban secondary wastewaters biologically treated with intensive cultures of a microalga Scenedesmus sp.Three daily feeding rates (575, 1150, 1750 mg dry weight algae day^?1 tank^?1), obtained by adjusting the flow of a tertiary effluent containing 115 mg dry weight of algae litre^?1, allowed average productions of 0·9, 1·6 and 2·6 g of Daphnia (wet basis) litre^?1 week^?1 which were proportional to the rations. When the flow of tertiary effluent was increased to 40 litres day^?1 tank^?1 (ad libitum), the average yield rose to 3·6 g of daphnids (wet basis) litre^?1 week^?1. The maximum population reached 48 000 individuals litre^?1. The daphnid/algae evergy conversion ratio was 0·4. Algae were removed by Daphnia at a maximum efficiency of 95%. The composition of Daphnia biomasses was 59·5% protein, 9·5% fat and 5·6% carbohydrate on a dry weight basis. No deficiencies in methionine and linolenic acid were noted.Results indicated the remarkable potential of urban wastewaters for the production of protein and the high productivity of Daphnia magna.     

Effects of temperature and salinity on the reproductive success of Arctic charr, Salvelinus alpinus (L.): egg composition, milt characteristics and fry survival

The effects of temperature and salinity on the reproductive success of Arctic charr, Salvelinus alpinus (L.), were examined by holding broodstock under the following conditions from mid‐May until the end of September: fresh water at ambient temperature (NFW; 8–16 °C); salt water (25–30‰) at ambient temperature (NSW; 4–10 °C); fresh water cooled to saltwater temperature (CFW; 4–10 °C); or salt water heated to freshwater temperature (HSW; 8–16 °C). The relative fecundity of females was similar among groups (P > 0.05; 2685 ± 706 eggs), but females reared in NSW produced significantly larger eggs than those raised in NFW. The highest spermatozoa concentrations were found in milt from males reared in SW and the highest milt glucose concentration was from males kept under coldwater conditions (CFW, NSW). Eggs from NSW and HSW females contained more proteins than eggs produced by NFW females. Eggs from NSW females also contained 40% more lipids than was observed in the other groups, and total energy content was 27% higher in eggs from NSW females than in eggs from NFW females. When FW was cooled (CFW), females produced eggs with protein contents similar to those in NSW, but the lipid contents remained 30% lower. Finally, the best survival at the eyed stage and at hatch was observed in families produced by NSW broodstock. Intermediate values were observed in families from NFW or CFW while the highest mortality occurred in families from the HSW group. All these results suggest that, under the experimental conditions used in the present study, coastal seawater conditions offered the most favourable summer rearing conditions with respect to the reproductive success of Arctic charr.     

Marennine,Promising Blue Pigments from a Widespread Haslea Diatom Species Complex

In diatoms, the main photosynthetic pigments are chlorophylls a and c, fucoxanthin, diadinoxanthin and diatoxanthin. The marine pennate diatom Haslea ostrearia has long been known for producing, in addition to these generic pigments, a water-soluble blue pigment, marennine. This pigment, responsible for the greening of oysters in western France, presents different biological activities: allelopathic, antioxidant, antibacterial, antiviral, and growth-inhibiting. A method to extract and purify marennine has been developed, but its chemical structure could hitherto not be resolved. For decades, H. ostrearia was the only organism known to produce marennine, and can be found worldwide. Our knowledge about H. ostrearia-like diatom biodiversity has recently been extended with the discovery of several new species of blue diatoms, the recently described H. karadagensis, H. silbo sp. inedit. and H. provincialis sp. inedit. These blue diatoms produce different marennine-like pigments, which belong to the same chemical family and present similar biological activities. Aside from being a potential source of natural blue pigments, H. ostrearia-like diatoms thus present a commercial potential for aquaculture, cosmetics, food and health industries.     

Maritime Halophyte Species from Southern Portugal as Sources of Bioactive Molecules

Extracts of five halophytes from southern Portugal (Arthrocnemum macrostachyum, Mesembryanthemum edule, Juncus acutus, Plantago coronopus and Halimione portulacoides), were studied for antioxidant, anti-inflammatory and in vitro antitumor properties. The most active extracts towards the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical were the methanol extracts of M. edule (IC₅₀ = 0.1 mg/mL) and J. acutus (IC₅₀ = 0.4 mg/mL), and the ether extracts of J. acutus (IC₅₀ = 0.2 mg/mL) and A. macrostachyum (IC₅₀ = 0.3 mg/mL). The highest radical scavenging activity (RSA) against the 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical was obtained in the ether extract of J. acutus (IC₅₀ = 0.4 mg/mL) and H. portulacoides (IC₅₀ = 0.9 mg/mL). The maximum total phenolic content (TPC) was found in the methanol extract of M. edule (147 mg gallic acid equivalents (GAE)/g) and in the ether extract of J. acutus (94 mg GAE/g). Significant decreases in nitric oxide (NO) production were observed after incubation of macrophages with lipopolysaccharide (LPS) and the chloroform extract of H. portulacoides (IC₅₀ = 109 µg/mL) and the hexane extract of P. coronopus (IC₅₀ = 98.0 µg/mL). High in vitro cytotoxic activity and selectivity was obtained with the ether extract of J. acutus. Juncunol was identified as the active compound and for the first time was shown to display selective in vitro cytotoxicity towards various human cancer cells.     

Important properties of bamboo pellets to be used as commercial solid fuel in China

Bamboo is a type of biomass material and has great potential as a bio-energy resource of the future in China. Some properties of bamboo pellets, length, diameter, moisture content (MC), particle density, bulk density, durability, fine content, ash, gross calorific value, combustion rate and heat release rate, were determined and the effects of MC and particle size (PS) on these properties were investigated in this research. The results showed that bamboo pellets will be the proposed new biomass solid fuel and have the potential to be developed as commercial pellets. All properties of bamboo pellets met the requirement of Pellet Fuels Institute Standard Specification for Residential/Commercial Densified Fuel. The gross calorific value of bamboo pellets also met the minimum requirement for making commercial pellets according to DIN 51731 (>17,500 J/g). The effects of MC on length, diameter, MC, particle density and bulk density were significant at p = 0.05. There were no significant differences between PS and all properties of bamboo pellets. Due to higher MC and larger PS, bamboo pellets exhibited higher combustion rates and heat release rates. This research represents an initial stage in the study of bamboo pellets, and its objectives provide guidelines for further research.     

栝楼丛生芽快繁体系的建立

利用栝楼的嫩芽作为外植体,进行离体组织培养,通过正交试验选择最适pH值和激素浓度,筛选出栝楼丛生芽的最适诱导培养基。结果表明,消毒时间为3 min时外植体损伤较小;pH为5.8的培养基外植体长势旺盛;3号芽诱导培养基丛生芽比较旺盛;2号生根培养基得到的根多且壮。栝楼丛生芽的快速繁殖体系为:0.1%HgCl2溶液外植体表面消毒3 min;丛生芽诱导的最适pH为5.8;最佳芽诱导培养基为:MS+0.5mg/L 6-BA+0.5 mg/L NAA;最佳芽生根培养基为:MS+0.2 mg/L NAA。