The movements and breeding site fidelity of the natterjack toad (Bufo calamita) in an urban park near Paris (France) with management recommendations

International audienceThe isolation of animal populations due to urban activities provides a useful framework for studying the consequences of landscape fragmentation. We studied a population of natterjack toads (Bufo calamita) in an urban park near Paris, France. In 2001 and 2002 we used radio-tracking to estimate the terrestrial movements of adults around their breeding sites. Twenty-four toads were equipped with internal transmitters in 2001 to record movements during and after the breeding period. In 2002, 19 males were released at 300 and 380 meters from their breeding ponds. Natterjack toad movements around and outside their breeding ponds were reduced compared to previous observations on this species. The only exchanges that were observed occurred between closely neighbouring breeding sites. During a translocation experiment in 2002, 58% of the displaced males returned to their site of capture and this happened mainly during the breeding period. The remaining 42% stayed close to the release site. There was no exchange of males between distant breeding sites. Natterjack toad conservation needs to take into account the high fidelity to a breeding site and the reduced breeding dispersal and homing ability of these animals. Conservation biology in urban landscapes constitutes a specific urban ecology with specific concepts such as 'population area'. Information from this study can assist land managers in establishing protected areas of high habitat quality around breeding ponds in urban areas, and managing parks for the protection of amphibian populations, particularly by facilitating exchanges between available areas

The impact of ceramides NP and AP on the nanostructure of stratum corneum lipid bilayer. Part I neutron diffraction and 2H NMR studies on multilamellar models based on ceramides with symmetric alkyl chain length distribution

We investigated the lamellar structure of ternary stratum corneum SC lipid model systems based on either the phytosphingosine type ceramide CER [NP] or CER[AP], supplemented by cholesterol and stearic acid as representative free fatty acid species. For the CER[NP] based membrane, neutron diffraction measurements revealed the coexistence of two lamellar phases, which markedly differ in their hydration properties. CER[NP] forms an extremely rigid and stable bilayer backbone and is at least partly sequestered in a separate phase which coexists with a second lamellar phase. At increased temperature, a structural re organization of the lipids was observed. One of the lamellar phases disappeared, while the remaining phase increased its repeat distance by about 1 A . Such a behaviour has not been described for SC lipid model membranes based on CER[AP] so far. Further, 2H NMR spectroscopic measurements on two SC lipid model systems based on either CER[NP] or CER[AP] in addition to cholesterol and perdeuterated stearic acid revealed a state of high lamellar order present in both samples, emphasizing the importance of the phytosphingosine type ceramides for the proper formation of stable SC bilayer structures. However, the CER[NP] based ternary model showed a state of higher lamellar order than the CER[AP] based system. Our results demonstrate that slight changes in the ceramides head groups CER[NP] with 3 hydroxyl groups vs. CER[AP] with 4 hydroxyl groups have a dramatic influence on the morphology of the lipid structures 1. Introduction It is well known that the outermost layer of the mammalian skin, the stratum corneum SC maintains homeostasis of the organism by protecting the body from various outer influences and uncon trolled water loss. With its intercellular lipid matrix surrounding the corneocytes, the SC is generally accepted to represent the major penetration barrier of the skin.1 3 Main constituents of the lipid lamellae are ceramides CERs in addition to cholesterol CHOL with its derivatives and free fatty acids FFA ,4,5 whereby particu larly the structural arrangement of these SC lipids in highly ordered and coherent multiple bilayers is regarded to be essential for the maintenance of the skin barrier properties.6 The CERs represent a very lipophilic and rigid class of molecules with only small aInstitute of Pharmacy, Martin Luther University, Wolfgang Langenbeck Stra e 4, 06120 Halle, Germany. E mail annett. schroeter pharmazie.uni halle.de; Tel 49 345 25025 bInstitute Soft Matter and Functional Materials, Helmholtz Zentrum Berlin, Hahn Meitner Platz 1, 14109 Berlin, Germany cInstitut Laue Langevin ILL , 6 Rue Jules Horowitz, 38042 Grenoble Cedex 9, France dInstitute of Medical Physics and Biophysics, University of Leipzig, Ha rtelstra e 16 18, 04107 Leipzig, Germany formed by these lipid