Ultrastructure of a mucous gland cell found in the tube feet of the starfishAsterina stellifera

Resumen Es describida la ultraestrutura de un segundo tipo de célula glandular mucosa que es encontrada en el pié ambulacrario de la estrella del marAsterina stellifera. Los gránulos secretores de esta célula tienen en su interior una ultraestrutura en forma de pequeños puntos densos y delicadas fibrillas, mas faltando una organizatión, principalmente comparada con la organizatión del otro tipo de granulo mucoso, también encontrado en el mismo pié ambulacrario.     

Myosin IXB variant increases the risk of celiac disease and points toward a primary intestinal barrier defect

Celiac disease is probably the best-understood immune-related disorder. The disease presents in the small intestine and results from the interplay between multiple genes and gluten, the triggering environmental factor. Although HLA class II genes explain 40% of the heritable risk, non-HLA genes accounting for most of the familial clustering have not yet been identified. Here we report significant and replicable association (P = 2.1 x 10(-6)) to a common variant located in intron 28 of the gene myosin IXB (MYO9B), which encodes an unconventional myosin molecule that has a role in actin remodeling of epithelial enterocytes. Individuals homozygous with respect to the at-risk allele have a 2.3-times higher risk of celiac disease (P = 1.55 x 10(-5)). This result is suggestive of a primary impairment of the intestinal barrier in the etiology of celiac disease, which may explain why immunogenic gluten peptides are able to pass through the epithelial barrier.     

Detection and imaging of atmospheric radio flashes from cosmic ray air showers

The nature of ultrahigh-energy cosmic rays (UHECRs) at energies >10(20) eV remains a mystery. They are likely to be of extragalactic origin, but should be absorbed within approximately 50 Mpc through interactions with the cosmic microwave background. As there are no sufficiently powerful accelerators within this distance from the Galaxy, explanations for UHECRs range from unusual astrophysical sources to exotic string physics. Also unclear is whether UHECRs consist of protons, heavy nuclei, neutrinos or gamma-rays. To resolve these questions, larger detectors with higher duty cycles and which combine multiple detection techniques are needed. Radio emission from UHECRs, on the other hand, is unaffected by attenuation, has a high duty cycle, gives calorimetric measurements and provides high directional accuracy. Here we report the detection of radio flashes from cosmic-ray air showers using low-cost digital radio receivers. We show that the radiation can be understood in terms of the geosynchrotron effect. Our results show that it should be possible to determine the nature and composition of UHECRs with combined radio and particle detectors, and to detect the ultrahigh-energy neutrinos expected from flavour mixing.     

A record of Permian subaqueous vent activity in southeastern Brazil

The remarkable occurrence of more than 4,500 conical siliceous mounds in an area of less than 1.5 square kilometres has been reported in the Paraná basin, near Anhembi, S?o Paulo, in southeastern Brazil. These structures, which are up to two metres high, are thought to have been formed at the margin of a very shallow, broad but waning internal sea, and it was originally suggested that they are stromatolites. Yet their restricted occurrence, unusual abundance and nearly pure siliceous composition have never been satisfactorily explained by this hypothesis. Here we report field and laboratory observations on their shape, construction, composition and mineralogy. On the basis of our data we suggest that the conical mounds are the result of subaqueous Late Permian vent activity in southwestern Gondwana. The present siliceous cone field differs considerably from other Palaeozoic siliceous hot spring deposits, such as those at Rhynie, Scotland, and the Drummond basin, Australia, and therefore represents an unusual occurrence of vent activity.     

Cellular and genetic mechanisms of self tolerance and autoimmunity

The mammalian immune system has an extraordinary potential for making receptors that sense and neutralize any chemical entity entering the body. Inevitably, some of these receptors recognize components of our own body, and so cellular mechanisms have evolved to control the activity of these 'forbidden' receptors and achieve immunological self tolerance. Many of the genes and proteins involved are conserved between humans and other mammals. This provides the bridge between clinical studies and mechanisms defined in experimental animals to understand how sets of gene products coordinate self-tolerance mechanisms and how defects in these controls lead to autoimmune disease.