Transcriptomic Characterization of Temperature Stress Responses in Larval Zebrafish

Temperature influences nearly all biochemical, physiological and life history activities of fish, but the molecular mechanisms underlying the temperature acclimation remains largely unknown. Previous studies have identified many temperature-regulated genes in adult tissues; however, the transcriptional responses of fish larvae to temperature stress are not well understood. In this study, we characterized the transcriptional responses in larval zebrafish exposed to cold or heat stress using microarray analysis. In comparison with genes expressed in the control at 28°C, a total of 2680 genes were found to be affected in 96 hpf larvae exposed to cold (16°C) or heat (34°C) for 2 and 48h and most of these genes were expressed in a temperature-specific and temporally regulated manner. Bioinformatic analysis identified multiple temperature-regulated biological processes and pathways. Biological processes overrepresented among the earliest genes induced by temperature stress include regulation of transcription, nucleosome assembly, chromatin organization and protein folding. However, processes such as RNA processing, cellular metal ion homeostasis and protein transport and were enriched in genes up-regulated under cold exposure for 48 h. Pathways such as mTOR signalling, p53 signalling and circadian rhythm were enriched among cold-induced genes, while adipocytokine signalling, protein export and arginine and praline metabolism were enriched among heat-induced genes. Although most of these biological processes and pathways were specifically regulated by cold or heat, common responses to both cold and heat stresses were also found. Thus, these findings provide new interesting clues for elucidation of mechanisms underlying the temperature acclimation in fish

Comparative hindlimb myology within the family Falconidae

A characteristical feature of a raptors’ hindlimb is their strengthen musculature that aids gripping prey with their sharp talons. To trace specific anatomical modifications it is necessary to study closely related species, with this aim, the myology of the hindlimb of the three subfamilies of Falconidae is explored. For this, a description of a Herpetotherinae member (Micrastur ruficollis) was made for the first time. The hindlimb muscle mass of Polyborinae, Falconinae and Herpetotherinae was compared according to their main function (flexion and extension) on their joints (femur, tibiotarsus, tarsometatarsus and digits). The pattern of Micrastur ruficollis resembles that of the Falconidae except for a few differences towards the development of certain muscles. As it is noteworthy the presence of the second belly of the musculus flexor cruris medialis (unique among birds), its identity will be discussed. Also, Micrastur ruficollis had the highest values of the hindlimb mass. Polyborinae and Falconinae had several differences between each other. The muscles mass of the hip and knee, both flexion and extension, were higher in the Polyborinae, this is in accordance to their more terrestrial habit. Instead, Falconinae had a higher mass in the m. flexor digitorum longus, m. flexor hallucis longus and m. tibialis cranialis, the most important muscles for gripping prey.Fil: Mosto, María Clelia. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin