The stage-dependent resistance of the chorion to external chemical damage and its relationship to embryonic diapause in the annual fish, Nothobranchius guentheri

The resistance of the embryonic chorion of the annual fish Nothobranchius guentheri to chemical damage in vivo was investigated by the exposure of the embryos to protease. Embryos at stages 20, 33, and 43 were the most resistant to enzymatic action. These stages of development correspond respectively to the stages at which diapause I, diapause II, and 'delayed hatching' may occur. The magnitude of the resistance was further enhanced when diapause was induced prior to the treatment.     

Inventory of Sarcophaginae (Diptera: Sarcophagidae) for the Humid Chaco,a poorly surveyed ecoregion of South America

ABSTRACT

Sarcophaginae is a large subfamily of sarcophagid flies (Diptera: Calyptratae: Oestroidea: Sarcophagidae) which have diverse habits, mainly sarcosaprophagous, and have forensic and sanitary importance. This is the first work that analyzes the fauna of Sarcophaginae exclusively in the Humid Chaco ecoregion where diversity of flies has scarcely been studied. This inventory was based on: a) samplings at different locations in the province of Chaco, Argentina, and in the state of Mato Grosso do Sul, Brazil; b) examination of entomological collections and c) bibliographic records. Sixty-two species of Sarcophaginae flies are included in this paper, of which 31 species are recorded for the first time in the Humid Chaco ecoregion. Ten species are new records for Argentina, two for Brazil and three for Paraguay. Lepidodexia (Neophytodes) lindneri Townsend, 1931, Lepidodexia (Notochaeta) adelina Mulieri, Schaefer, Duré and González, 2018, Lepidodexia (Pachygraphomima) lenti Lopes, 1980, Oxysarcodexia berthet Dufek and Mulieri, 2017, Oxysarcodexia ibera Dufek and Mulieri, 2017 and Retrocitomyia paraguayensis Lopes, 1985 are registered as endemic species of the Humid Chaco ecoregion. Species with forensically and sanitary importance are listed. Some comments on species distribution previously published in catalogues are provided.     

Endocannabinoids and β-amyloid-induced neurotoxicity in vivo: effect of pharmacological elevation of endocannabinoid levels

We investigated the involvement of endocannabinoids in the control of neuronal damage and memory retention loss in rodents treated with the β-amyloid peptide (1–42) (BAP). Twelve days after stereotaxic injection of BAP into the rat cortex, and concomitant with the appearance in the hippocampus of markers of neuronal damage, 2-arachidonoyl glycerol, but not anandamide, levels were enhanced in the hippocampus. VDM-11 (5 mg/kg, i.p.), an inhibitor of endocannabinoid cellular reuptake, significantly enhanced rat hippocampal and mouse brain endocannabinoid levels when administered sub-chronically starting either 3 or 7 days after BAP injection and until the 12–14th day. VDM-11 concomitantly reversed hippocampal damage in rats, and loss of memory retention in the passive avoidance test in mice, but only when administered from the 3rd day after BAP injection. We suggest that early, as opposed to late, pharmacological enhancement of brain endocannabinoid levels might protect against β-amyloid neurotoxicity and its consequences. Received 26 January 2006; received after revision 24 March 2006; accepted 12 April 2006     

The stage-dependent resistance of the chorion to external chemical damage and its relationship to embryonic diapause in the annual fish,Nothobranchius guentheri

Summary The resistance of the embryonic chorion of the annual fishNothobranchius guentheri to chemical damage in vivo was investigated by the exposure of the embryos to protease. Embryos at stages 20, 33, and 43 were the most resistant to enzymatic action. These stages of development correspond respectively to the stages at which diapause I, diapause II, and delayed hatching may occur. The magnitude of the resistance was further enhanced when diapause was induced prior to the treatment.     

Effect of maternal under-nutrition on pup body weight and hypothalamic endocannabinoid levels

Dietary long-chain polyunsaturated fatty acids are known to influence brain levels of the endocannabinoid anandamide in newborn pigs and mice. Furthermore, endocannabinoids were shown to control pup suckling and body weight in mice, and food intake in adult rodents. Here we determined the effect of maternal under-nutrition during gestation, lactation, or both, on body weight, and on the levels of endocannabinoids and expression of cannabinoid CB₁ receptors and fatty acid amide hydrolase in the hypothalamus of rat pups at weaning (21 days old) or adult rats (4 months old). Maternal under-nutrition resulted in a striking decrease in body weight of weaning rats, paralleled by a decrease in the hypothalamic levels of the endocannabinoid anandamide, but not of 2-arachidonoylglycerol. No significant change in the hypothalamic expression of either cannabinoid CB₁ receptors or fatty acid amide hydrolase mRNA was detected in any of the three groups of weaned pups. The decrease in pup body weight and hypothalamic anandamide levels was not observable in 4-month-old rats from any of the three groups. These data suggest that maternal under-nutrition causes a decrease in hypothalamic anandamide levels and loss of body weight, and confirm a crucial role for endocannabinoid signalling in neonatal development. Received 4 November 2002; received after revision 29 November 2002; accepted 16 December 2002 RID="*" ID="*"Corresponding author.     

Shrinkage‐Based Tests of Predictability

In this paper we derive a test of predictability by exploring the possibility that forecasts from a given model, adjusted by a shrinkage factor, will display lower mean squared prediction errors than forecasts from a simple random walk. This generalizes most previous tests which compare forecast errors of a benchmark model with errors of a proposed alternative model, not allowing for shrinkage. We show that our test is a particular extension of a recently developed test of the martingale difference hypothesis. Using simulations we explore the behavior of our test in small and moderate samples. Numerical results indicate that the test has good size and power properties. Finally, we illustrate the use of our test in an empirical application within the exchange rate literature. Copyright © 2012 John Wiley & Sons, Ltd.