RESUMO
Processes for decoding the genetic information in cells, including transcription, replication, recombination and repair, involve the deformation of DNA from its equilibrium structures such as bending, stretching, twisting, and unzipping of the double helix. Single-molecule manipulation techniques have made it possible to control DNA conformation and simultaneously detect the induced changes, revealing a rich variety of mechanically-induced conformational changes and thermodynamic states. These single-molecule techniques helped us to reveal the physics of DNA and the processes involved in the passing on of the genetic code.
RESUMO
Amphid sensilla are the primary olfactory, chemoreceptive, and thermoreceptive organs in nematodes. Their function is well described for the model organism Caenorhabditis elegans, but it is not clear to what extent we can generalize these findings to distantly related nematodes of medical, economic, and agricultural importance. Current detailed descriptions of anatomy and sensory function are limited to nematodes that recent molecular phylogenies would place in the same taxonomic family, the Rhabditidae. Using serial thin-section transmission electron microscopy, we reconstructed the anatomy of the amphid sensilla in the more distantly related nematode, Acrobeles complexus (Cephalobidae). Amphid structure is broadly conserved in number and arrangement of cells. Details of cell anatomy differ, particularly for the sensory neurite termini. We identify an additional sensory neuron not found in the amphid of C. elegans and propose homology with the C. elegans interneuron AUA. Hypotheses of homology for the remaining sensory neurons are also proposed based on comparisons between C. elegans, Strongyloides stercoralis, and Haemonchus contortus.
