The dog and rat olfactory receptor repertoires

Background

Dogs and rats have a highly developed capability to detect and identify odorant molecules, even at minute concentrations. Previous analyses have shown that the olfactory receptors (ORs) that specifically bind odorant molecules are encoded by the largest gene family sequenced in mammals so far.

Results

We identified five amino acid patterns characteristic of ORs in the recently sequenced boxer dog and brown Norway rat genomes. Using these patterns, we retrieved 1,094 dog genes and 1,493 rat genes from these shotgun sequences. The retrieved sequences constitute the olfactory receptor repertoires of these two animals. Subsets of 20.3% (for the dog) and 19.5% (for the rat) of these genes were annotated as pseudogenes as they had one or several mutations interrupting their open reading frames. We performed phylogenetic studies and organized these two repertoires into classes, families and subfamilies.

Conclusion

We have established a complete or almost complete list of OR genes in the dog and the rat and have compared the sequences of these genes within and between the two species. Our results provide insight into the evolutionary development of these genes and the local amplifications that have led to the specific amplification of many subfamilies. We have also compared the human and rat ORs with the human and mouse OR repertoires.     

Effects of stimuli shape and polarization in evoking deimatic patterns in the European cuttlefish, Sepia officinalis, under varying turbidity conditions

Cuttlefish possess the complex ability to identify approaching threats and then to selectively express the appropriate defense. We examined the visual cues used by Sepia officinalis cuttlefish during predator detection and the responses they selected. Using computer-generated stimuli, we set out to quantitate the deimatic responses to artificial looming stimuli of different shapes and contrasts. Defensive behavior gradually intensified as geometrical shapes resembled an image of a fish. Therefore, in addition to an object’s size or its sudden increase in size, cuttlefish use form recognition to identify a threat. Cuttlefish demonstrated equal performance in predator detection trough clear water when presented with intensity versus polarization contrasts. However, when the water turbidity increased, the cuttlefish still detected looming fish shapes based on polarization contrast even when intensity information alone did not suffice. These results demonstrate the interplay between intensity and polarization information transmission and processing in the spatial domain. As nectobenthic organisms, cuttlefish probably experience low visibility conditions on a regular basis. The ability to see further into turbid water and to better detect an approaching object would be beneficial for their survival.     

Identification of PDZ ligands by docking-based virtual screening for the development of novel analgesic agents

Disrupting the interaction between the PDZ protein, PSD-95, and its target ligands (such as the glutamate NMDA receptor or the serotonin 5-HT_2A receptor) was found to reduce hyperalgesia in various models of neuropathic pain. Here, we set out to identify lead molecules which would interact with PSD-95, and hence, would potentially display analgesic activity. We describe the virtual screening of the Asinex and Cambridge databases which together contain almost one million molecules. Using three successive docking filters and visual inspection, we identified three structural classes of molecules and synthesized a potential lead compound from each class. The binding of the molecules with the PDZ domains of PSD-95 was assessed by ¹H–¹⁵N HSQC NMR experiments. The analgesic activity of the best ligand, quinoline 2, was evaluated in vivo in a model of neuropathic pain and showed promising results.     

Attenuated Bordetella pertussis vaccine candidate BPZE1 promotes human dendritic cell CCL21-induced migration and drives a Th1/Th17 response

New vaccines against pertussis are needed to evoke full protection and long-lasting immunological memory starting from the first administration in neonates--the major target of the life-threatening pertussis infection. A novel live attenuated Bordetella pertussis vaccine strain, BPZE1, has been developed by eliminating or detoxifying three important B. pertussis virulence factors: pertussis toxin, dermonecrotic toxin, and tracheal cytotoxin. We used a human preclinical ex vivo model based on monocyte-derived dendritic cells (MDDCs) to evaluate BPZE1 immunogenicity. We studied the effects of BPZE1 on MDDC functions, focusing on the impact of Bordetella-primed dendritic cells in the regulation of Th and suppressor T cells (Ts). BPZE1 is able to activate human MDDCs and to promote the production of a broad spectrum of proinflammatory and regulatory cytokines. Moreover, conversely to its parental wild-type counterpart BPSM, BPZE1-primed MDDCs very efficiently migrate in vitro in response to the lymphatic chemokine CCL21, due to the inactivation of pertussis toxin enzymatic activity. BPZE1-primed MDDCs drove a mixed Th1/Th17 polarization and also induced functional Ts. Experiments performed in a Transwell system showed that cell contact rather than the production of soluble factors was required for suppression activity. Overall, our findings support the potential of BPZE1 as a novel live attenuated pertussis vaccine, as BPZE1-challenged dendritic cells might migrate from the site of infection to the lymph nodes, prime Th cells, mount an adaptive immune response, and orchestrate Th1/Th17 and Ts responses.     

Transport of inorganic phosphate inPseudomonas aeruginosa

Inorganic phosphate transport by wild-typePseudomonas aeruginosa cells grown in a phosphate-limited medium involves a biphasic process. The uptake obeys Michaelis-Menten kinetics with respective apparentK _m values of 1.1 M and 10 M for the high- and low-affinity systems. These systems may be also differentiated by their sensitivity to osmotic shock, by their specificity towards phosphite, pyrophosphate, arsenate, and some phosphonates and also by their energy requirements. The two phosphate transport systems fromP. aeruginosa are compared with the two major systems (Pst and Pit) characterized inEscherichia coli.