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La relativa inactividad de la Progesterona por vía oral ha determinado el estudio de numerosas sustancias de actividad progestacional por vía oral. El aumento de la excreción de Pregnandiol en presencia de deficiencias hepáticas y su relativa inactividad por vía oral, indica que el sitio principal de degradación de la Progesterona es el hígado. No obstante la conversión de Progesterona a Pregnandiol puede ocurrir en lugares extra-hepáticos sin que éstos presenten un importante mecanismo de inactivación. Cuando se administra Progesterona continuamente por varias semanas una mayor proporción. 25 a 30 % de Pregnandiol aparece en la orina.

The identification of habitat requirements of invasive species is essential to evaluate their spread and to assess the vulnerability of recipient ecosystems. We studied the distribution and abundance of the invasive signal crayfish (Pacifastacus leniusculus) in 43 sites in northern Spain and analysed the relationships with several abiotic and biotic parameters of the aquatic ecosystems. Our results indicated that the abundance of signal crayfish was positively associated with vegetation cover and negatively associated with boulders. Also, its abundance was positively correlated with water temperature, organic matter, cations (e.g. sodium), anions (e.g. sulfates) and abundance of some native fish species (Parachondrostoma miegii and Luciobarbus graellsii). We concluded that the habitat of signal crayfish is among salmonid stretches (headwaters) with cold waters and low proportion of organic debris, and among cyprinid stretches (low waters) with warmer waters which it inhabits with another invasive crayfish, the red swamp crayfish (Procambarus clarkii). Our analysis indicated that the presence of signal crayfish is limited in the uppermost stretches by lower water temperatures and a lower proportion of organic debris. The existence of a natural environmental limiting factor in upstream reaches facilitates the conservation of aquatic ecosystems and native fauna. [ABSTRACT FROM AUTHOR]

In birds, early experiences determine the later behavioural phenotype of individuals and their way of adapting to the challenges they encounter in their environment. We investigated how the degree of exposure of barn owl chicks to humans and their biological parents influenced their behavioural response to humans and different environments. Only the treatment groups raised by human beings, or those that remained for less time with their biological parents (15 days posthatching), learned to fly towards their trainer. However, the two groups of chicks that were raised the longest by their biological parents (20 and 25 days) never flew towards their trainer. In these last groups, the filial imprint was shown not to be able to be reversed. Neophobia was estimated to emerge between 17 and 19 days of age, as barn owls were able to recognize the environment in which they were habituated, showing fear of a new environment. Birds were able to recognize the person who raised them and objects with which they had been raised. The results obtained in this work can help to establish breeding protocols in this and other species of birds of prey, which improve their adaptability to the environment where they will live, whether in captivity or in the wild. • The way barn owls are imprinted determines their adaptability to the environment where they will live. • Filial imprint and neophobia in barn owls determine their survival success in wilderness. • Objects that surround barn owls in their early stages can be recognized by them later, reducing their stress. • Between 17 and 19 days of age, barn owls are able to recognize the environment they are. [ABSTRACT FROM AUTHOR]