Preparing Adult Drosophila melanogaster for Whole Brain Imaging during Behavior and Stimuli Responses.

We present a method developed specifically to image the whole Drosophila brain during ongoing behavior such as walking. Head fixation and dissection are optimized to minimize their impact on behavior. This is first achieved by using a holder that minimizes movement hindrances. The back of the fly's head is glued to this holder at an angle that allows optical access to the whole brain while retaining the fly's ability to walk, groom, smell, taste and see. The back of the head is dissected to remove tissues in the optical path and muscles responsible for head movement artefacts. The fly brain can subsequently be imaged to record brain activity, for instance using calcium or voltage indicators, during specific behaviors such as walking or grooming, and in response to different stimuli. Once the challenging dissection, which requires considerable practice, has been mastered, this technique allows to record rich data sets relating whole brain activity to behavior and stimulus responses.

Pseudomonas cremoris sp. nov., a novel proteolytic species isolated from cream.

During a study investigating the microbiota of raw milk and its semi-finished products, strains WS 5106T and WS 5096 were isolated from cream and skimmed milk concentrate. They could be assigned to the genus Pseudomonas by their 16S rRNA sequences, but not to any validly named species. In this work, a polyphasic approach was used to characterize the novel strains and to investigate their taxonomic status. Examinations based on the topology of core genome phylogenomy as well as average nucleotide identity (ANIm) comparisons suggested a novel Pseudomonas species within the Pseudomonas fluorescens subgroup. With pairwise ANIm values of 90.1 and 89.8 %, WS 5106T was most closely related to Pseudomonas nabeulensis CECT 9765T and Pseudomonas kairouanensis CECT 9766T. The G+C content of strain WS 5106T was 60.1 mol%. Morphologic analyses revealed Gram-stain-negative, aerobic, catalase and oxidase positive, rod-shaped and motile cells. Proteolysis on skimmed milk agar as well as lipolysis on tributyrin agar occurred at both 28 and 6 °C. Tolerated growth conditions were temperatures between 4 and 34 °C, pH values between 6.0 and 8.0, and salt concentrations of up to 5 %. Fatty acid profiles showed a pattern typical for Pseudomonas, with C16 : 0 as the dominant component. The major cellular polar lipids were phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol and the dominating quinone was Q-9. Based on these results, it is proposed to classify the strains as a novel species, Pseudomonas cremoris sp. nov., with WS 5106T (=DSM 111143T=LMG 31863T) as type strain and WS 5096 (=DSM 111129=LMG 31864) as an additional strain.