Emily Baird | PubMed Health

PubMed2005

Visual control of flight speed in honeybees.

Visual control of flight speed in honeybees (Apis mellifera L.) was investigated by training them to fly through a specially constructed tunnel in which the motion, contrast and texture of the patterns lining the walls could be varied. Manipulation of pattern motion revealed that the speed of flight is controlled by regulating the image motion that is experienced by the eyes. Flight speed is surprisingly robust to changes in the contrast and/or spatial texture of the visual environment, suggesting that the underlying movement-detecting mechanisms estimate the speed of image motion in the eye largely independently of these parameters. This ensures that flight speed depends primarily on the distances to nearby surfaces and not upon their particular visual properties, such as contrast or visual texture. The removal of image motion cues drastically compromises the regulation of flight speed, underscoring their role in this function.

Animals↗

PubMed2003

Competition between two MHC binding registers in a single peptide processed from myelin basic protein influences tolerance and susceptibility to autoimmunity.

Experimental allergic encephalomyelitis (EAE) is an animal model for multiple sclerosis induced by stimulating myelin basic protein (MBP)-specific T cells. The MBP-specific repertoire in B10.PL mice is shaped by tolerance mechanisms that eliminate MBP121-150-specific T cells. In contrast, MBPAc1-11-specific T cells escape tolerance and constitute the encephalitogenic repertoire. To determine if this differential tolerance is caused by differences in the abundance of MBP epitopes generated by processing, MBP peptides were eluted from I-Au complexes and analyzed by mass spectrometry. Peptides were identified from both the NH2-terminal and MBP121-150 regions. Unexpectedly, MBPAc1-18 and Ac1-17, which contain the MBPAc1-11 epitope, were much more abundant than MBP121-150 peptides. The results demonstrate that competition between two I-Au binding registers, a low affinity register defined by MBPAc1-11 and a high affinity register defined by MBP5-16, prevents most of the NH2-terminal naturally processed peptides from binding in the MBPAc1-11 register. The small fraction of MBPAc1-18 bound in the MBPAc1-11 register is not sufficient to induce tolerance but provides a ligand for MBPAc1-11-specific T cells during disease. These results provide a basis for both the lack of tolerance to MBPAc1-11 and the ability of this epitope to become a target during autoimmunity.

Animals↗