title: Functional correlates of positional and gender-specific renal asymmetry in Drosophila.
abstract: BACKGROUND
  In humans and other animals, the internal organs are positioned asymmetrically in the body cavity, and disruption of this body plan can be fatal in humans. The mechanisms by which internal asymmetry are established are presently the subject of intense study; however, the functional significance of internal asymmetry (outside the brain) is largely unexplored. Is internal asymmetry functionally significant, or merely an expedient way of packing organs into a cavity?
  
  
  RESULTS
  Like humans, Drosophila shows internal asymmetry, with the gut thrown into stereotyped folds. There is also renal asymmetry, with the rightmost pair of renal (Malpighian) tubules always ramifying anteriorly, and the leftmost pair always sitting posteriorly in the body cavity. Accordingly, transcriptomes of anterior-directed (right-side) and posterior-directed (left-side) Malpighian (renal) tubules were compared in both adult male and female Drosophila. Although genes encoding the basic functions of the tubules (transport, signalling) were uniformly expressed, some functions (like innate immunity) showed positional or gender differences in emphasis; others, like calcium handling or the generation of potentially toxic ammonia, were reserved for just the right-side or left-side tubules, respectively. These findings correlated with the distinct locations of each tubule pair within the body cavity. Well known developmental genes (like dorsocross, dachshund and doublesex) showed continuing, patterned expression in adult tubules, implying that somatic tissues maintain both left-right and gender identities throughout life. Gender asymmetry was also noted, both in defence and in male-specific expression of receptors for neuropeptide F and sex-peptide: NPF elevated calcium only in male tubules.
  
  
  CONCLUSIONS
  Accordingly, the physical asymmetry of the tubules in the body cavity is directly adaptive. Now that the detailed machinery underlying internal asymmetry is starting to be delineated, our work invites the investigation, not just of tissues in isolation, but in the context of their unique physical locations and milieux.
authors.affiliation: Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom.
authors.forename: Venkateswara R
authors.initials: VR
authors.lastname: Chintapalli
authors.forename: Selim
authors.initials: S
authors.lastname: Terhzaz
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Mohammed
authors.initials: M
authors.lastname: Al Bratty
authors.forename: David G
authors.initials: DG
authors.lastname: Watson
authors.forename: Pawel
authors.initials: P
authors.lastname: Herzyk
authors.forename: Shireen A
authors.initials: SA
authors.lastname: Davies
authors.forename: Julian A T
authors.initials: JA
authors.lastname: Dow
mesh_terms: D000818:Animals; D001692:Biological Transport; D015415:Biomarkers / Q000378:metabolism*; D015153:Blotting, Western; D020013:Calcium Signaling; D004331:Drosophila melanogaster / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D005260:Female; D020869:Gene Expression Profiling; D007668:Kidney / Q000002:abnormalities* / Q000378:metabolism; D008297:Male; D008317:Malpighian Tubules / Q000002:abnormalities* / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012737:Sex Factors
chemical_list: D015415:Biomarkers; D012333:RNA, Messenger