CRDB: Database of Chemosensory Receptor Gene Families in Vertebrate

Chemosensory receptors (CR) are crucial for animals to sense the environmental changes and survive on earth. The emergence of whole-genome sequences provides us an opportunity to identify the entire CR gene repertoires. To completely gain more insight into the evolution of CR genes in vertebrates, we identified the nearly all CR genes in 25 vertebrates using homology-based approaches. Among these CR gene repertoires, nearly half of them were identified for the first time in those previously uncharacterized species, such as the guinea pig, giant panda and elephant, etc. Consistent with previous findings, we found that the numbers of CR genes vary extensively among different species, suggesting an extreme form of ‘birth-and-death’ evolution. For the purpose of facilitating CR gene analysis, we constructed a database with the goals to provide a resource for CR genes annotation and a web tool for exploring their evolutionary patterns. Besides a search engine for the gene extraction from a specific chromosome region, an easy-to-use phylogenetic analysis tool was also provided to facilitate online phylogeny study of CR genes. Our work can provide a rigorous platform for further study on the evolution of CR genes in vertebrates

The anatomy and histology of the nasal cavity of the koala (Phascolarctos cinereus).

The anatomy of the nose of the koala was studied from fixed 0.5 cm thick sections of a whole head. Right and left nasal cavities are separated by a slender septum which does not exhibit 'swell bodies'. Dorsal and ventral conchae are simple curved plates without elaborate scrolls; the ventral concha is recurved to form a bulla. The nasal cavity communicates with confluent rostral maxillary and frontal air sinuses. A ventrocaudal maxillary sinus opens from the ventral meatus close to the choanae. There is a frontal sinus dorsocaudal to the ethmoid region which does not communicate with the nasal cavity. Nasal and oral cavities communicate via incisive ducts, opening just rostral to the vomeronasal ducts. The vomeronasal organ extends from the level of the fourth incisor to the first cheek tooth. The histology of the nasal area was examined by light and electron microscopy. Stratified squamous epithelium extends from the external nares to the incisive duct; nerve endings are frequent in association with its basal cells. Respiratory epithelium lines the nasal cavity proper, olfactory epithelium covers the ethmoturbinate bones, caudal dorsa concha and caudal septum, and sensory epithelium lines the medial aspect of the vomeronasal organ. Nasal secretions are provided by goblet cells and conchal and septal glands in respiratory areas, and by Bowman's and vomeronasal glands in the sensory areas. There are no lateral nasal glands, maxillary sinus glands or swell body glands

The structure and distribution of nasal glands in four marsupial species.

The structure and distribution of nasal glands in four marsupial species were studied by light and electron microscopy. The species studied were the honey possum (Tarsipes rostratus), the bandicoot (Isoodon macrourus), the koala (Phascolarctos cinereus) and the agile wallaby (Macropus agilis). Glands were grouped and described according to their location. Those of general distribution (goblet cells and olfactory glands) were similar in structures and distribution in all specimens. Glands of the lateral nasal wall include the lateral nasal, maxillary sinus and turbinate glands. The lateral nasal and maxillary sinus glands were absent in the adult koala but occupied large areas in the other species. Turbinate glands were best developed rostrally and ventrally in the nasal cavity. On the nasal septum, Tarsipes and Isoodon had well developed glands associated with vascular 'swell bodies'. These were poorly developed to Macropus though septal glands were abundant. 'Swell bodies' were absent in Phascolarctos and glands were sparse. Tubular vomeronasal glands were present in all species and most extensive in Tarsipes. In Isoodon, there was a posterior ventral septal gland associated with the septal olfactory organ. The fine structural features of secretory cells and ducts are described and their potential role discussed in terms of chemoreception and temperature and humidity control

The olfactory apparatus of the bandicoot (Isoodon macrourus): fine structure and presence of a septal olfactory organ.

The structure and extent of olfactory epithelium in the bandicoot (Isoodon macrourus) were examined by light and electron microscopy. Sensory epithelium covers most of the dorsal conchae, though non-sensory epithelium lines ventrally facing scrolls. The middle conchae are partly covered by olfactory epithelium, the proportion of olfactory to ciliated respiratory epithelium increasing caudally. Ventral conchae are lined by non-sensory ciliated epithelium. The nasal septum ends short of the floor of the nasal cavity in its caudal two thirds. It is covered dorsally by olfactory epithelium. The ventral margin has rounded lateral extensions which carry the isolated strips of olfactory epithelium which form the septal olfactory organ. The fine structure of the olfactory epithelium is the same in all areas. Cell types include olfactory receptors, supporting cells, two types of basal cell and rarer pale and brush cells. There is considerable morphological variation in olfactory cells, and evidence suggestive of continuing turnover in the receptor cell population

Decreased levels of ascorbic acid in lung following exposure to ozone

Mice were exposed to concentrations of 20, 40 and 200 ppm ozone in air for 30 min. Ozone exposure decreased lung ascorbic acid levels and increased lung weight by up to 50% in a dose related manner. On incubation in Krebsphosphate solution, lung slices from mice exposed to 200 ppm ozone released a smaller fraction of their content of ascorbic acid into the medium than did lung slices from control mice, suggesting that there was a preferential loss of extracellular ascorbic acid during ozone exposure. These results are consistent with the proposed function of ascorbic acid as an extracellular antioxidant in lungs