Abstract  Predator-induced cloning (asexual reproduction), with reduced size as consequence of cloning, suggests a novel adaptation to the threat of predation. Although cloning is a common reproductive strategy of many plants and animals, cloning in response to stimuli from predators has, at present, been documented only in the larvae (plutei) of the sand dollar, Dendraster excentricus. Other studies report larval cloning in echinoderms under optimal conditions of food and temperature. A burst of asexuality should be favored when environmental conditions are conducive to growth, but it is less clear that cloning is advantageous when conditions indicate risk from predators. This study tested the hypothesis that the small size of predator-induced clones reduces vulnerability during encounters with planktivorous fish. Successful cloning was inferred from an increase in larval density, a reduction in larval size and stage, and some direct observations of budding. All clones were smaller than uncloned sibling larvae, suggesting an advantage against visual predators. Pair-wise predation trials demonstrated that planktivorous fish ate more uncloned sibling plutei than small clones. These results offer a new ecological context for asexual reproduction: rapid size reduction as a defense. If the identifiable cues for cloning in echinoderm larvae (food and predators) are linked in nature, then larval cloning may be a response to a single ecological scenario rather than two separate and unrelated conditions.

• Content Type Journal Article
• Category Original Paper
• DOI 10.1007/s00227-010-1410-z
• Authors
  • Dawn Vaughn, University of Washington Department of Biology, Friday Harbor Laboratories Seattle Washington 98195 USA

• Journal Marine Biology
• Online ISSN 1432-1793
• Print ISSN 0025-3162

Abstract  Animals inhabiting hydrothermal vents and cold seeps face conditions that are challenging for survival. In particular, these two habitats are characterized by chronic hypoxia, sometimes reaching complete anoxia. The characteristics of the scaphognathite and gills were studied in four species of shrimp and three species of crabs from hydrothermal vents and cold seeps, in order to highlight potential adaptations that could enhance oxygen acquisition in comparison with shallow-water relatives. All the vent and seep species studied here exhibit significantly larger scaphognathites, likely allowing more water to flow over their gills per stroke of this appendage. This is probably more energetically efficient that prolonged hyperventilation. In contrast to annelids, vent and seep decapods usually do not possess enlarged gills, a phenomenon likely due to the physical limitations imposed by the size of the gill chamber. In the vent shrimp Rimicaris exoculata and the vent crab Bythograea thermydron, however, there is a significantly higher specific gill surface area linked to a higher number of lamellae per gram of gill. Again in contrast to annelids, the diffusion distance through the gills is not strikingly different between the vent shrimp Alvinocaris komaii and the shallow-water species Palaemon spp. This may indicate that the epithelium and cuticle of the decapod gills are already optimized for oxygen uptake and that reducing the thickness of these compartments is not physically possible without affecting the physical integrity of the gills.

• Content Type Journal Article
• Category Original Paper
• DOI 10.1007/s00227-010-1406-8
• Authors
  • Johan Decelle, Station Biologique de Roscoff, CNRS-UPMC Equipe Ecophysiologie des Invertébrés des Milieux Extrêmes 29680 Roscoff France
  • Ann C. Andersen, Station Biologique de Roscoff, CNRS-UPMC Equipe Ecophysiologie des Invertébrés des Milieux Extrêmes 29680 Roscoff France
  • Stéphane Hourdez, Station Biologique de Roscoff, CNRS-UPMC Equipe Génétique de l’Adaptation en Milieux Extrêmes 29680 Roscoff France

• Journal Marine Biology
• Online ISSN 1432-1793
• Print ISSN 0025-3162

Abstract  Cork oak forests invaded by the Argentine ant Linepithema humile have a lower abundance and biomass of arthropod prey for birds than uninvaded forests. We studied whether the biomass of breeding insectivorous birds was also lower in invaded areas. We explored this and other possible effects of the ant invasion on the bird community by censusing birds in transects located in four invaded and four uninvaded forest sites in Catalonia (NE Spain) for 3 years. Redundancy analysis showed only slight differences in the community composition between forests. Two insectivorous species, Luscinia megarhynchos and Fringilla coelebs, tended to be less abundant in invaded areas although two others, Phylloscopus bonelli and Sylvia melanocephala, showed the opposite trend. Overall, the differences in prey biomass between invaded and uninvaded areas did not entail a biomass shift in the guild of insectivorous birds, regardless of whether they were shrub or canopy foragers. The main role of the habitat structure in determining bird densities and food resources being non-limiting in the studied forests are two possible non-exclusive explanations for this inconsistency. At today’s levels, the Argentine ant invasion does not appear to have greatly determined the insectivorous bird assemblage of the forests evaluated.

• Content Type Journal Article
• Category Original Paper
• DOI 10.1007/s10531-010-9799-8
• Authors
  • Pere Pons, Universitat de Girona Departament de Ciències Ambientals Campus de Montilivi 17071 Girona Catalonia Spain
  • Josep Maria Bas, Universitat de Girona Departament de Ciències Ambientals Campus de Montilivi 17071 Girona Catalonia Spain
  • David Estany-Tigerström, Universitat de Girona Departament de Ciències Ambientals Campus de Montilivi 17071 Girona Catalonia Spain

• Journal Biodiversity and Conservation
• Online ISSN 1572-9710
• Print ISSN 0960-3115

Obesity and other inactivity related diseases are increasing at an alarming rate especially in Western societies. Because of this, it is important to understand the regulating mechanisms involved in physical activity behavior. Much research has been done in regard to the psychological determinants of physical activity behavior; however, little is known about the underlying genetic and biological factors that may contribute to regulation of this complex trait. It is true that a significant portion of any trait is regulated by genetic and biological factors. In the case of voluntary physical activity behavior, these regulating mechanisms appear to be concentrated in the central nervous system. In particular, the dopamine system has been shown to regulate motor movement, as well as motivation and reward behavior. The pattern of regulation of voluntary physical activity by the dopamine system is yet to be fully elucidated. This review will summarize what is known about the dopamine system and regulation of physical activity, and will present a hypothesis of how this signaling pathway is mechanistically involved in regulating voluntary physical activity behavior. Future research in this area will aid in developing personalized strategies to prevent inactivity related diseases.

Relaxin family peptide systems and the central nervous system.

Cell Mol Life Sci. 2010 Mar 7;

Authors: Callander GE, Bathgate RA

Since its discovery in the 1920s, relaxin has enjoyed a reputation as a peptide hormone of pregnancy. However, relaxin and other relaxin family peptides are now associated with numerous non-reproductive physiologies and disease states. The new millennium bought with it the sequence of the human genome and subsequently new directions for relaxin research. In 2002, the ancestral relaxin gene RLN3 was identified from genome databases. The relaxin-3 peptide is highly expressed in a small region of the brain and in species from teleost to primates and has both conserved sequence and sites of expression. Combined with the discovery of the relaxin family peptide receptors, interest in the role of the relaxin family peptides in the central nervous system has been reignited. This review explores the relaxin family peptides that are expressed in or act upon the brain, the receptors that mediate their actions, and what is currently known of their functions.

PMID: 20213277 [PubMed - as supplied by publisher]