The renin-angiotensin system in uninephrectomized adrenalectomized rats

Résumé La surrénalectomie bilatérale chez des rats uninéphrectomisés produit une augmentation très marquée de la concentration de rénine plasmatique, ainsi que de l'activité de la G6PD dans la macula densa. Cependant, malgré une diminution de la granularité des cellules juxtaglomérulaires, on n'observe aucune modification du contenu en rénine du rein. Ces observations indiquent que, dans cette condition expérimentale, le rein qui reste est capable de réagir avec forte augmentation de la sécrétion de rénine.     

Sex difference in liver tryptophan pyrrolase activity of starved rats

Zusammenfassung Die Tryptophanpyrrolase (LTP) ausgewachsener weiblicher Ratten nimmt während 4-stündiger Hungerperiode von 1,06µM Kynurenin auf 2,26µM/g/h zu. Sie erreicht nach 24 h wieder Normalwerte, um dann während einer 8tägigen Hungerperiode auf 5,75µM/g/h anzusteigen. Die LTP männlicher Ratten zeigt nur unbedeutenden Anstieg während gleicher Hungerperioden.     

Testing hypothesized evolutionary shifts toward stress tolerance in hybrid Helianthus species

We examined how plant traits related to growth and resource use have evolved during hybrid speciation and specialization into stressful habitats. Two desert sunflower species of homoploid hybrid origin are endemic to habitats with lower soil nutrient levels than those of their ancestral parent species. We hypothesized that the hybrid species would exhibit greater tolerance to low levels of soil nutrients than their parental species. The 2 hybrid species, Helianthus anomalus and H. deserticola , and their parental species, H. annuus and H. petiolaris , were compared for plant traits and growth through reproduction under 3 nutrient levels in a greenhouse study. An additional seedling study compared species for maximum seedling relative growth rate under optimum conditions. The hybrid species did have greater tolerance of nutrient limitation than the parental species, demonstrated by a resistance to change in stem height and diameter growth across treatments. A similar trend was observed in total biomass at final harvest. This ability to maintain growth may be partially explained by maintained investment in photosynthetic enzymes regardless of nutrient treatment. Though the hybrid species were more tolerant of nutrient stress, differences in the hybrid response to nutrient stress compared to the parental species' response were much smaller than expected from habitat comparisons. Helianthus anomalus has evolved a classic stress-tolerant phenotype, having long leaf lifespan, tough leaves, and slower early seedling relative growth rate. While both hybrid species have a conservative growth strategy, which confers greater stress tolerance than the parental species possess, functional trait differences among the hybrids suggest that the 2 species have experienced vastly different selective pressures.     

An Analytical Solution for Backscatter Tomography

We utilize the Novikov-Natterer algorithm for non-uniform attenuation to invert the backscatter projections formed by the scatter of X-rays.The backscatter signal is treated as an emitter in a non-uniformly attenuating medium.This type of tomography has applications in radiology and dentistry for which metals effectively block the transmission of X-rays.Scanning for metals also has applications in security/baggage screening.The results show that when the forward scattering angle is zero,the algorithm,with a...     

Following evolution of bacterial antibiotic resistance in real time

A new study reports the development of the 'morbidostat', a device that allows for continuous culture of bacteria under a constant drug selection pressure using computer feedback control of antibiotic concentration. This device, together with bacterial whole-genome sequencing, allowed the authors to follow the evolution of resistance-conferring mutations in Escherichia coli populations in real time, providing support for deterministic evolution of resistance in some situations.