<Emphasis Type="Italic">Actinokineospora</Emphasis><Emphasis Type="Italic">mzabensis</Emphasis> sp. nov., a novel actinomycete isolated from Saharan soil

A novel actinomycete strain, designated PAL84, was isolated from a Saharan soil sample collected from Béni-Isguen, Ghardaïa (South of Algeria). This strain was studied for its taxonomic position using a polyphasic approach and was identified as a member of the genus Actinokineospora. Phylogenetic analysis showed that strain PAL84 had 16S rRNA gene sequence similarities with members of the genus Actinokineospora ranging from 96.2 % (Actinokineospora inagensis DSM 44258^T) to 97.8 % (Actinokineospora baliensis NBRC 104211^T). The strain was observed to produce pinkish-purple aerial mycelium and purplish red substrate mycelium, which fragmented readily into chains of non-motile elements. The optimum growth temperature and pH were found to be 25–30 °C and 5.0–7.0, respectively. The cell-wall hydrolysate of strain PAL84 was found to contain meso-diaminopimelic acid and the diagnostic whole-cell sugars were identified as arabinose and galactose. The predominant menaquinone was identified as MK-9 (H₄). The major fatty acids were found to be iso-C_16:0, iso-C_15:0, iso-C_16:1 H and iso-C_16:0 2OH. The diagnostic phospholipid detected was phosphatidylethanolamine. The genotypic and phenotypic data show that the strain represents a novel species of the genus Actinokineospora, for which the name Actinokineospora mzabensis sp. nov. is proposed, with the type strain PAL84^T (=DSM 45961^T = CECT 8578^T).     

Description of <Emphasis Type="Italic">Geodermatophilus bullaregiensis</Emphasis> sp. nov.

The taxonomic position of an aerobic actinobacterial strain, BMG841^T, isolated from the Bulla Regia monument (Tunisia) and exhibiting a high resistance to gamma-radiation (D10 ~9 kGy) was determined using polyphasic approach. The optimal growth range was found to be 25–35 °C at pH of 7.0–8.5. The strain was observed to form black dry colonies. Chemotaxonomic characteristics of the isolate showed a cell wall type III, with galactose and glucose as diagnostic sugars; phosphatidylcholine, phosphatidylinositol, diphosphatidylglycerol, phosphatidylethanolamine and an unidentified glycolipid as main polar lipids; and MK-9(H₄) as the predominant menaquinone. The major cellular fatty acids were identified as iso-C_16:0 and iso-C_15:0. Phylogenetic analysis indicated that strain BMG841^T represents a novel member of the genus Geodermatophilus with high 16S rRNA gene sequence identity with Geodermatophilus saharensis (98.28 %). Based on phylogenetic and phenotypic analysis, strain BMG841^T is proposed as the type strain (=DSM 46841^T = CECT 8821^T) of a novel species, Geodermatophilus bullaregiensis.     

Structural determinants of odorant recognition by the human olfactory receptors OR1A1 and OR1A2

An interaction of odorants with olfactory receptors is thought to be the initial step in odorant detection. However, ligands have been reported for only 6 out of 380 human olfactory receptors, with their structural determinants of odorant recognition just beginning to emerge. Guided by the notion that amino acid positions that interact with specific odorants would be conserved in orthologs, but variable in paralogs, and based on the prediction of a set of 22 of such amino acid positions, we have combined site-directed mutagenesis, rhodopsin-based homology modelling, and functional expression in HeLa/Olf cells of receptors OR1A1 and OR1A2. We found that (i) their odorant profiles are centred around citronellic terpenoid structures, (ii) two evolutionary conserved amino acid residues in transmembrane domain 3 are necessary for the responsiveness of OR1A1 and the mouse ortholog Olfr43 to (S)-(-)-citronellol, (iii) changes at these two positions are sufficient to account for the differential (S)-(-)-citronellol responsiveness of the paralogs OR1A1 and OR1A2, and (iv) the interaction sites for (S)-(-)-citronellal and (S)-(-)-citronellol differ in both human receptors. Our results show that the orientation of odorants within a homology modelling-derived binding pocket of olfactory receptor orthologs is defined by evolutionary conserved amino acid positions.     

The genome of Hyperthermus butylicus: a sulfur-reducing, peptide fermenting, neutrophilic Crenarchaeote growing up to 108 degrees C

Hyperthermus butylicus, a hyperthermophilic neutrophile and anaerobe, is a member of the archaeal kingdom Crenarchaeota. Its genome consists of a single circular chromosome of 1,667,163 bp with a 53.7% G+C content. A total of 1672 genes were annotated, of which 1602 are protein-coding, and up to a third are specific to H. butylicus. In contrast to some other crenarchaeal genomes, a high level of GUG and UUG start codons are predicted. Two cdc6 genes are present, but neither could be linked unambiguously to an origin of replication. Many of the predicted metabolic gene products are associated with the fermentation of peptide mixtures including several peptidases with diverse specificities, and there are many encoded transporters. Most of the sulfur-reducing enzymes, hydrogenases and electron-transfer proteins were identified which are associated with energy production by reducing sulfur to H(2)S. Two large clusters of regularly interspaced repeats (CRISPRs) are present, one of which is associated with a crenarchaeal-type cas gene superoperon; none of the spacer sequences yielded good sequence matches with known archaeal chromosomal elements. The genome carries no detectable transposable or integrated elements, no inteins, and introns are exclusive to tRNA genes. This suggests that the genome structure is quite stable, possibly reflecting a constant, and relatively uncompetitive, natural environment.     

Assessing the Ideal Free Distribution: Do Guppies Use Aggression as Public Information about Patch Quality?

Aggression can be costly to foragers, yet some recent research suggests that foragers should use aggression as a cue to patch quality (the attractive aggression hypothesis). If aggression is predictive of patch quality, then the attractive aggression hypothesis predicts that the distribution of foragers should follow the distribution of aggression. If, instead, aggression is repulsive because it is costly, then the distribution of foragers should diverge from the distribution of aggression. We tested the attractive aggression hypothesis using female guppies, Poecilia reticulata , and found that the distribution of foragers followed the distribution of food, but was unaffected by the distribution of aggression. These data do not support the attractive aggression hypothesis, but instead suggest that the distribution of aggression is a consequence of the distribution of foragers, and that aggression is not used as public information about patch quality.     

cis-Chlorobenzene Dihydrodiol Dehydrogenase (TcbB) from Pseudomonas sp. Strain P51, Expressed in Escherichia coli DH5α(pTCB149), Catalyzes Enantioselective Dehydrogenase Reactions

cis-Chlorobenzene dihydrodiol dehydrogenase (CDD) from Pseudomonas sp. strain P51, cloned into Escherichia coli DH5α(pTCB149) was able to oxidize cis-dihydrodihydroxy derivatives (cis-dihydrodiols) of dihydronaphthalene, indene, and four para-substituted toluenes to the corresponding catechols. During the incubation of a nonracemic mixture of cis-1,2-indandiol, only the (+)-cis-(1R,2S) enantiomer was oxidized; the (−)-cis-(S,2R) enantiomer remained unchanged. CDD oxidized both enantiomers of cis-1,2-dihydroxy-1,2,3,4-tetrahydronaphthalene, but oxidation of the (+)-cis-(1S,2R) enantiomer was delayed until the (−)-cis-(1R,2S) enantiomer was completely depleted. When incubated with nonracemic mixtures of para-substituted cis-toluene dihydrodiols, CDD always oxidized the major enantiomer at a higher rate than the minor enantiomer. When incubated with racemic 1-indanol, CDD enantioselectively transformed the (+)-(1S) enantiomer to 1-indanone. This stereoselective transformation shows that CDD also acted as an alcohol dehydrogenase. Additionally, CDD was able to oxidize (+)-cis-(1R,2S)-dihydroxy-1,2-dihydronaphthalene, (+)-cis-monochlorobiphenyl dihydrodiols, and (+)-cis-toluene dihydrodiol to the corresponding catechols.