On the moulding of senescence by natural selection in sexual and partly sexual populations

Under a wide variety of dynamic environmental conditions, natural selection appears to favor reproductive investment in a sexually produced offspring, carrying only half of the mother’s genes, over the investment in an asexually produced offspring, genetically identical to her. It is maintained that the same environmental conditions must affect the evolutionary cost and benefit of an investment in the prolongation of one’s own life versus an investment in sexual reproduction, in favor of the latter. The effects of different environmental conditions on the division of resources among sexual reproduction, asexual reproduction and prolongation of life are studied.     

Full‐field swept‐source optical coherence tomography and neural tissue classification for deep brain imaging

Optical coherence tomography can differentiate brain regions with intrinsic contrast and at a micron scale resolution. Such a device can be particularly useful as a real‐time neurosurgical guidance tool. We present, to our knowledge, the first full‐field swept‐source optical coherence tomography system operating near a wavelength of 1310 nm. The proof‐of‐concept system was integrated with an endoscopic probe tip, which is compatible with deep brain stimulation keyhole neurosurgery. Neuroimaging experiments were performed on ex vivo brain tissues and in vivo in rat brains. Using classification algorithms involving texture features and optical attenuation, images were successfully classified into three brain tissue types.     

Pyrrolnitrin Production by an Enterobacter agglomerans Strain with a Broad Spectrum of Antagonistic Activity Towards Fungal and Bacterial Phytopathogens

Strain IC1270 of Enterobacter agglomerans has been previously described as a producer of a complex of chitinolytic enzymes and as an antagonist of many fungal phytopathogens [Chernin et al. (1995) Appl. Env. Microbiol. 61:1720–1726]. Here we show that this strain also produces an antibiotic that was purified by TLC and HPLC and identified by UV, IR, MS, and NMR analyses as pyrrolnitrin [3-chloro-4-(2′-nitro-3′-chlorophenyl)pyrrole]. The purified antibiotic is efficient against many phytopathogenic bacteria and fungi in vitro. This is the first piece of evidence showing that pyrrolnitrin can be produced by bacteria other than Pseudomonas and that one bacterial strain can simultaneously produce chitinolytic enzymes and pyrrolnitrin. The possible role of a combination of chitinases and pyrrolnitrin in antagonism is discussed.