Search results for "Reproduction"
showing 10 items of 752 documents
Acute, chronic and sublethal effects of the herbicide propanil on Daphnia magna.
2003
Acute and chronic toxicity tests with propanil were conducted on Daphnia magna. The 24 and 48 h LC50 were 43.74 and 5.01 mg/l respectively. Chronic toxicity tests were carried out using sublethal propanil concentrations (0.07, 0.10, 0.21 and 0.55 mg/l) during 21 days. The effect of propanil on survival, reproduction and growth of D. magna organisms was monitored. The parameters used to evaluate herbicide effect on reproduction were: mean total young ones per female, mean brood size, time to first reproduction, mean number broods per female and intrinsic rate of natural increase (r). Survival and growth (body length) were also determined after 21 days of exposure to the herbicide. Reproducti…
Biochemical stress response in tetradifon exposed Daphnia magna and its relationship to individual growth and reproduction
2009
Abstract Environmental risk assessment of chemicals toxicity requires the use of costly and labor-intensive chronic data and short-term tests provide additional information. Energy budget is used by the animals for their growth, reproduction, and metabolism and it is reduced in case of toxic stress. Tetradifon acaricide is frequently used in the European Mediterranean region and it is implicated in aquatic environmental pollution. Previous studies showed that the EC50-24 h of tetradifon on Daphnia magna was 8.92 mg/L. Based on that, D. magna were exposed to sublethal tetradifon concentrations of 0.10, 0.18, 0.22 and 0.44 mg/L for five days in order to investigate their effect on intermediat…
Synchronization protocols in Spanish Merino sheep Reduction in time to estrus by the addition of eCG to a progesterone-based estrus synchronization p…
2015
Abstract An appropriate management of reproduction allows ewes to breed at a more intensive rhythm, more compatible with economic efficiency of farms. Hence, the objectives of the present work were to evaluate a traditional estrus synchronization protocol (based on medroxyprogesterone acetate-impregnated intravaginal sponges combined or not with equine chorionic gonadotropin) on a Merino sheep herd during the breeding season, in order to determine the best working protocol for this breed. A total of 277 sheep, blocked by age (200 ewes and 77 ewe lambs) were randomly allocated to four groups, two of ewes (E and Ee) and two of ewe lambs (L and Le). All females received 60 mg MAP (medroxyproge…
Does risk of small mustelid predation affect the oestrous cycle in the bank vole,Clethrionomys glareolus?
1996
Female bank voles suppress their reproduction when the risk of small mustelid predation is high. The mechanism for this reproductive suppression is unknown. Because rodents are known to alter their oestrous cycle in response to changing environmental conditions, the eVect of predation risk on the oestrous cycle of bank vole females was studied. The oestrous cycles of 24 females divided into two treatments (predation risk and control) were observed for 20 days using female receptivity as an indication of oestrus. Voles exposed for 2-3 h a day for 20 days to the close presence of a least weasel, Mustela nivalis nivalis, had fewer oestrous cycles than control females exposed to a domestic rabb…
Experimental increase of worker diversity benefits brood production in ants
2021
Background The reproductive division of labor of eusocial insects, whereby one or several queens monopolize reproduction, evolved in a context of high genetic relatedness. However, many extant eusocial species have developed strategies that decrease genetic relatedness in their colonies, suggesting some benefits of the increased diversity. Multiple studies support this hypothesis by showing positive correlations between genetic diversity and colony fitness, as well as finding effects of experimental manipulations of diversity on colony performance. However, alternative explanations could account for most of these reports, and the benefits of diversity on performance in eusocial insects stil…
Relaciones de parentesco en las nuevas familias: disociación entre maternidad/paternidad biológica, genética y social
2015
Se describen y analizan las relaciones de parentesco en las familias monoparentales, homoparentales, tardías o de edad avanzada, con embarazos múltiples, reconstituidas, adoptivas y las que recurren a las técnicas de reproducción asistida. En estas familias se puede producir una disociación entre relaciones conyugales y relaciones filiales; entre sexualidad y reproducción; entre pareja conyugal, pareja parental y pareja progenitora; y la creación de lazos de filiación independientemente de tener una relación de pareja. Asimismo, frente a la biparentalidad y heteroparentalidad, se pueden establecer relaciones de monoparentalidad, homoparentalidad, coparentalidad y pluriparentalidad. Estas fa…
Dietary rescue of altered metabolism gene reveals unexpected [i]Drosophila[/i] mating cues
2015
Running title: Dietary rescue of metabolic mutation and reproduction; To develop and reproduce, animals need long-chain Mono and PolyUnsaturated Fatty Acids (MUFAs; PUFAs). Although some UFAs can be synthesized by the organism, others must be provided by the diet. The gene desat1, involved in Drosophila melanogaster UFA metabolism, is necessary for both larval development and for adult sex pheromone communication. We first characterized desat1 expression in larval tissues. Then, we found that larvae in which desat1 expression was knocked down throughout development died during the larval stages when raised on standard food. By contrast pure MUFAs or PUFAs, but not saturated FAs, added to th…
desat1: A Swiss army knife for pheromonal communication and reproduction?
2012
International audience; The desat1 gene possesses an extraordinary-maybe unique-feature in the control of sensory communication systems: it codes for the two principal and complementary aspects-the emission and the reception-of Drosophila sex pheromones. These two complex aspects depend on separate genetic control indicating that desat1 pleiotropically acts on pheromonal communication. This gene also control other characters either related to reproduction and to osmoregulation. Such a functional pleiotropy may be related to the molecular structure of desat1 gene which combines a highly conserved coding region with fast evolving regulatory regions: It produces at least five transcripts all g…
Lignes et points : Illustration, impressionnisme littéraire et procédés
2020
International audience; Cette conférence a porté de manière générale sur les rapports entre illustration et procédés de reproduction. Elle est plus précisément consacrée à l’utilisation de la photogravure dans le livre illustré britannique de la fin du 19ème siècle. L’exemple choisi est le recueil d’essais London Impressions (Constable, 1898) d’Alice Meynell, illustré par l’artiste britannique William Hyde. Peintre et aquafortiste, Hyde collaborait avec l’inventeur écossais Donald Cameron-Swan (1863-1951) de la Swan Electric Engraving Company, spécialisée dans le cliché trait comme dans le cliché simili. À la croisée de pratiques autographiques et d’opérations mécaniques, la photogravure al…
A New Third Sector Intellectual Capital Model
2016
The Intellectual Capital (IC) report has become a fundamental tool in the disclosure of non-profit activities, since it is necessary to use a correct framework to represent IC. To achieve the aim of the paper the work is developed as follows: the existing literature on non-profit organizations (NPOs) and IC is examined and relevant aspects to be measured by IC indicators and disclosed by an IC report in the above context are brought into focus. Then extant frameworks for IC reporting are outlined in order to verify whether they fit the aspects qualified as relevant in NPOs and it is pointed out what they lack with reference to the NPOs context. The aim of the paper is to propose an original…