Effect of gamma and e-beam radiation on the essential oils of Thymus vulgaris thymoliferum, Eucalyptus radiata, and Lavandula angustifolia

The microbiological contamination of raw plant materials is common and may be adequately reduced by radiation processing. This study evaluated the effects of gamma- and e-beam ionizing radiations (25 kGy) on three plants used as food or as medicinal products (Thymus vulgaris L., Eucalyptus radiata D.C., and Lavandula angustifolia Mill.) as well as their effects on extracted or commercial essential oils and pure standard samples. Comparison between irradiated and nonirradiated samples was performed by GC/FID and GC/MS. At the studied doses, gamma and e-beam ionizing radiation did not induce any detectable qualitative or quantitative significant changes in the contents and yields of essential oils immediately after ionizing radiation of plants or commercial essential oils and standards. As the maximum dose tested (25 kGy) is a sterilizing dose (much higher than doses used for decontamination of vegetable drugs), it is likely that even decontamination with lower doses will not modify yields or composition of essential oils of these three plants.     

Hormonal changes during meiotic maturation and ovulation in the brook trout (Salvelinus fontinalis)

The plasma levels of estradiol-17 (E2), 17, 20-dihydroxy-4-pregnen-3-one (17,20-P) and gonadotropin (GTH) were measured in brook trout (Salvelinus fontinalis) during the period from the end of vitellogenesis to postovulation. Blood samples were taken according to specific stages of maturation, including germinal vesicle breakdown (GVBD) and ovulation. E2 levels were quite high (45 ng/ml) at the end of vitellogenesis (and prior to GVBD) and dropped precipitously by GVBD (2 ng/ml). They remained low through ovulation and postovulation. 17,20-P levels were low prior to GVBD (0.7 ng/ml) and increased dramatically at GVBD (148 ng/ml). The levels of 17,20-P remained high at ovulation (142 ng/ml) and then dropped significantly within 24 h to approximately half of the ovulatory values. They decreased even further by 7 days postovulation. GTH levels rose gradually through GVBD and ovulation from a postvitellogenic level of approximately 3 ng/ml to a 7 day postovulatory value of approximately 10 ng/ml. The overall results; 1) decrease in estradiol prior to GVBD, 2) increase in 17,20-P at GVBD and 3) gradual GTH rise through GVBD and ovulation, are similar to those reported for other salmonids.     

Post-emergent herbicidal activity of cineole derivatives

Essential oils are being investigated as potential herbicides or to provide leads to new environmentally and socially acceptable herbicides. Novel hydroxy and ester derivatives of 1,8-cineole and 1,4-cineole were synthesised, by chemical and biological methods, and have shown pre-emergence herbicidal activity against annual ryegrass and radish. Effects on post-emergence activity of these derivatives, as well as 1,8-cineole, eucalyptus oil and the carboxylic acids from which the esters were derived, against annual ryegrass and radish, are reported here. Results suggest that reduced root and shoot growth observed in pre-emergence herbicidal bioassays were due to post-emergence activity rather than delayed germination. All tested substances had a dose-dependent, post-emergence herbicidal activity against annual ryegrass and radish with many derivatives showing improved activity relative to 1,8-cineole and high-cineole eucalyptus oil. However, results do not support the postulate that cineole esters would be more active than their respective carboxylic acid and the hydroxy cineole. Phytotoxicity of ester derivatives may be due to metabolic cleavage of the esters to the hydroxy cineole and carboxylic acid within the plant.     

非生产天数——提高母猪繁殖群效率的关键

正母猪的非生产天数(NPD)是指每个繁殖周期,或每年母猪或青年母猪既非妊娠又非泌乳的天数,它是影响猪群繁殖生产效率最关键的指标。某些记录系统还包括青年母猪从进场到配种的时间,但这段时间的长短与青年母猪的引进程序有关,不同猪场之间存在很大差异,现在只探讨第一胎之后的非生产天数。     

Attitudes of Rural Communities Toward Dispersing African Wild Dogs in South Africa

Subsistence pastoralists often view large carnivores negatively given that any loss of livestock is likely to represent a significant economic cost. Consequently, large carnivore conservation initiatives in rural landscapes should incorporate appropriate human–carnivore conflict mitigation strategies. In this study, structured interviews with local residents (n = 247) were used for determining attitudes toward African wild dogs (Lycaon pictus) among rural communities neighboring two protected areas in KwaZulu-Natal, South Africa. Contrary to expectations, the majority of respondents (58%) were generally positive toward wild dogs. This was probably due to a lack of livestock depredation by wild dogs and relatively high levels of formal education among respondents. Respondents with greater knowledge of wild dogs and conflict mitigation had more positive attitudes, and most were aware of effective husbandry techniques. The positive attitudes observed in these rural communities may benefit wild dog dispersal from natal home ranges and the future conservation of this endangered carnivore.     

Adaptation de la teneur en enzymes digestives de l'hepatopancreas de Palaemon serratus (Crustacea,Decapoda), a la composition d'aliments experimentaux

The effects of the carbohydrate and protein composition of compound diets on growth rate and on the amylase and protease content of the hepatopancreas have been studied in Palaemon serratus.The best growth rate for animals weighing between 80 and 380 mg is obtained with a diet containing 3.5% carbohydrate and 64% protein. Diets which are very rich in carbohydrate and poor in protein result in poor growth and high mortality; the same is true for foods containing a high concentration of only one protein.Variations in the wet weight of the hepatopanereas and in the total digestive enzymatic activities are linked to variations in the growth rate of the shrimp.Maximal specific amylase activity is reached when assimilable carbohydrate amounts to 2.8%. Maximal specific protease activity is reached when the food protein level reaches 45%. When the amounts of carbohydrate and protein are higher or lower, the values of specific enzymatic proteins diminish.