Organ culture of rat skeletal muscle subjected to intermittent activity

Zusammenfassung Es wird eine Methode angegeben, um die wichtigen biochemischen und pharmakologischen Untersuchungen an Muskulatur (Rattenmuskel) bei Erhaltung der mechanischen Aktivität über 8 Tage durchzuführen.     

Rapid change in drift of the Australian plate records collision with Ontong Java plateau

The subduction of oceanic plateaux, which contain extraordinarily thick basaltic crust and are the marine counterparts of continental flood-basalt provinces, is an important factor in many current models of plate motion and provides a potential mechanism for triggering plate reorganization. To evaluate such models, it is essential to decipher the history of the collision between the largest and thickest of the world's oceanic plateaux, the Ontong Java plateau, and the Australian plate, but this has been hindered by poor constraints for the arrival of the plateau at the Melanesian trench. Here we present (40)Ar-(39)Ar geochronological data on hotspot volcanoes in eastern Australian that reveal a strong link between collision of the Greenland-sized Ontong Java plateau with the Melanesian arc and motion of the Australian plate. The new ages define a short-lived period of reduced northward plate motion between 26 and 23 Myr ago, coincident with an eastward offset in the contemporaneous tracks of seamount chains in the Tasman Sea east of Australia. These features record a brief westward deflection of the Australian plate as the plateau entered and choked the Melanesian trench 26 Myr ago. From 23 Myr ago, Australia returned to a rapid northerly trajectory at roughly the same time that southwest-directed subduction began along the Trobriand trough. The timing and brevity of this collisional event correlate well with offsets in hotspot seamount tracks on the Pacific plate, including the archetypal Hawaiian chain, and thus provide strong evidence that immense oceanic plateaux, like the Ontong Java, can contribute to initiating rapid change in plate boundaries and motions on a global scale.     

Melatonin,clock genes and mitochondria in sepsis

After the characterization of the central pacemaker in the suprachiasmatic nucleus, the expression of clock genes was identified in several peripheral tissues including the immune system. The hierarchical control from the central clock to peripheral clocks extends to other functions including endocrine, metabolic, immune, and mitochondrial responses. Increasing evidence links the disruption of the clock genes expression with multiple diseases and aging. Chronodisruption is associated with alterations of the immune system, immunosenescence, impairment of energy metabolism, and reduction of pineal and extrapineal melatonin production. Regarding sepsis, a condition coursing with an exaggerated response of innate immunity, experimental and clinical data showed an alteration of circadian rhythms that reflects the loss of the normal oscillation of the clock. Moreover, recent data point to that some mediators of the immune system affects the normal function of the clock. Under specific conditions, this control disappears reactivating the immune response. So, it seems that clock gene disruption favors the innate immune response, which in turn induces the expression of proinflammatory mediators, causing a further alteration of the clock. Here, the clock control of the mitochondrial function turns off, leading to a bioenergetic decay and formation of reactive oxygen species that, in turn, activate the inflammasome. This arm of the innate immunity is responsible for the huge increase of interleukin-1β and entrance into a vicious cycle that could lead to the death of the patient. The broken clock is recovered by melatonin administration, that is accompanied by the normalization of the innate immunity and mitochondrial homeostasis. Thus, this review emphasizes the connection between clock genes, innate immunity and mitochondria in health and sepsis, and the role of melatonin to maintain clock homeostasis.     

A new cellular function for peroxisomes related to oxygen free radicals?

Summary Although in cell biology peroxisomes are still young organelles, it is becoming increasingly clear that they are involved in important cellular functions. Recent results have indicated the presence of the metalloenzyme superoxide dismutase in peroxisomes and the production of superoxide free radicals (O ₂ ^– ) in these oxidative organelles. These findings, together with other experimental evidence, point towards the existence of new roles for peroxisomes in cellular active oxygen metabolism, something that has a potential impact in multiple areas of cell biology, particularly in biochemistry and biomedicine.     

A new nurse frog from Southwestern Amazonian highlands,with notes on the phylogenetic affinities of Allobates alessandroi (Aromobatidae)

ABSTRACT

Few studies have focused on the diverse fauna of southwestern Brazilian Amazonia. This region, spared from large-scale human occupation until the second half of the twentieth century, has been threatened by expanding agriculture, logging, and mining. Here, we describe a new nurse frog (Allobates, Aromobatidae) from the open highland habitats of Serra dos Pacaás Novos, one of the few large remnants of relatively intact native vegetation in the Brazilian state of Rondônia. The new species is diagnosed by its metallic orange dorsal colouration, weakly expanded discs on hands, and presence of two subarticular tubercles on Finger IV. A phylogenetic analysis based on DNA sequence data recovered the new species as more closely related to nurse frogs from the Madeira and Tapajós River basins; this pattern may reflect a history of dispersal uphill from a lowland ancestor. Our results also indicate that the generic assignment of Allobates alessandroi (Grant and Rodriguez, 2001), a high-elevation species from the Andes of Peru, needs to be reassessed; we discuss the phylogenetic affinities of this species based on morphological attributes.

http://www.zoobank.org/urn:lsid:zoobank.org:act:79131D82-B1B6-455D-AD9A-676D7E0783BC     

Strategies for the Study of Complex Socio-Economic Systems: an Approach Using Agent-Based Simulation

The present paper proposes a research strategy that integrates top-down and bottom-up approaches, aimed at the study of complex socio-economic systems. Through a theoretical analysis, it is demonstrated throughout the text a strategy that allows the articulation between agent-based simulation approaches and methods of deductive and phenomenological basis capable of providing social sciences with unprecedented accuracy due to ethical and methodological limitations imposed by the study object until then. This is because this type of hybrid approach allows the construction of a deep systemic articulation between the micro and the macro, as advocated by the General Theory of Systems, at the same time as it is supported by systematic experiments that give new light to the study of the socio-economic complexity.