Specification of pattern is fundamental to the development of a multicellular organism. The Malpighian (renal) tubule of Drosophila melanogaster is a simple epithelium that proliferates under the direction of a single tip cell into three morphologically distinct domains. However, systematic analysis of a panel of over 700 P{GAL4} enhancer trap lines reveals unexpected richness for such an apparently simple tissue. Using numerical analysis, it was possible formally to reconcile apparently similar or complementary expression domains and thus to define at least five genetically defined domains and multiple cell types. Remarkably, the positions of domain boundaries and the numbers of both principal and secondary (''stellate'') cell types within each domain are reproducible to near single-cell precision between individual animals. Domains of physiological function were also mapped using transport or expression assays. Invariably, they respect the boundaries defined by enhancer activity. These genetic domains can also be visualized in vivo, both in transgenic and wild-type f lies, providing an ''identified cell'' system for epithelial physiology. Building upon recent advances in Drosophila Malpighian tubule physiology, the present study confirms this tissue as a singular model for integrative physiology.

Non-syndromic cleft lip with or without cleft palate (CL/P, MIM 119530) is among the most common of major birth defects. Homozygosity for a nonsense mutation of PVRL1, W185X, results in an autosomal recessive CL/P syndrome on Margarita Island, CLPED1 (ref. 1). Here we demonstrate highly significant association between heterozygosity for this mutation and sporadic, non-syndromic CL/P in northern Venezuela.

Vacuolar ATPases play major roles in endomembrane and plasma membrane proton transport in eukaryotes.A Drosophila melanogaster cDNA encoding vha55, the 55-kDa vacuolar ATPase (V-ATPase) regulatory B-subunit, was characterized and mapped to 87C2-4 on chromosome 3R. A fly line was identified that carried a single lethal P-element insertion within the coding portion of gene, and its LacZ reporter gene revealed elevated expression in Malpighian tubules, rectum, antennal palps, and oviduct, regions where V-ATPases are believed to play a plasma membrane, rather than an endomembrane, role. The P-element vha55 insertion was shown to be allelic to a known lethal complementation group l(3)SzA ‫؍(‬ l(3)87Ca) at 87C, for which many alleles have been described previously. Deletions of the locus have been shown to be larval lethal, whereas point mutations show a range of phenotypes from subvital to embryonic lethal, implying that severe alleles confer a partial dominant negative phenotype. The P-element null allele of vha55 was shown also to suppress ectopic sex combs in Polycomb males, suggesting that transcriptional silencing may be modulated by genes other than those with known homeotic or DNA binding functions. The vacuolar ATPase1 is a multisubunit complex, related to the F 1 /F 0 ATPase (1-3). The transmembrane protonophore is made of six copies of a 16-kDa proteolipid, linked by further subunits to a catalytic headgroup comprising three copies each of a 67-kDa A-subunit and a 57-kDa B-subunit. Traditionally, the A-subunit is described as catalytic, whereas the B-subunit is considered regulatory, although in reality the active sites for nucleotide binding and proton flux may lie in the interfaces between neighboring A-and B-subunits (4). Although there is known to be very high conservation within the V-ATPase family, the 57-kDa subunit is interesting as several transcripts are known, some of which are tissue-specific (5, 6). It has been argued further that choice of B-subunit transcript may affect the overall subunit composition of the holoenzyme by influencing the choice of other subunits during assembly of the V 1 headgroup (6), and the B-subunit is phosphorylated by a component of AP-2, the clathrin assembly complex (7), suggesting a role in control of vesicle trafficking.V-ATPases, although originally defined as endosomal, are now known to energize plasma membrane transport in a variety of tissues, such as kidney, osteoclasts, and frog skin (8); and loss of kidney V-ATPase function in autoimmune disease is clinically significant (9). In an invertebrate model, a painstaking biochemical purification of particles on the goblet cell apical membranes of lepidopteran midgut (10) showed that the invertebrate K ϩ pump (11) was in fact a V-ATPase (12), driving a K ϩ /H ϩ antiporter (13) to produce a remarkably potent transport system (14, 15). Monospecific antibodies against the lepidopteran plasma membrane V-ATPase were used to demonstrate plasma membrane V-ATPases immunocytochemically in salivary glands, Malpighian (renal)...

VHL is part of an SCF related E3-ubiquitin ligase complex with`gatekeeper' function in renal carcinoma. However, no mutations have been identi®ed in VHL interacting proteins in wild type VHL tumors. We previously reported that the TRC8 gene was interrupted by a t(3;8) translocation in a family with hereditary renal and non-medullary thyroid cancer. TRC8 encodes a multi-membrane spanning protein containing a RING-H2 ®nger with in vitro ubiquitin ligase activity. We isolated the Drosophila homologue, DTrc8, and studied its function by genetic manipulations and a yeast 2-hybrid screen. Human and Drosophila TRC8 proteins localize to the endoplasmic reticulum. Loss of either DTrc8 or DVhl resulted in an identical ventral midline defect. Direct interaction between DTrc8 and DVhl was con®rmed by GST-pulldown and co-immunoprecipitation experiments. CSN-5/JAB1 is a component of the COP9 signalosome, recently shown to regulate SCF function. We found that DTrc8 physically interacts with CSN-5 and that human JAB1 localization is dependent on VHL mutant status. Lastly, overexpression of DTrc8 inhibited growth consistent with its presumed role as a tumor suppressor gene. Thus, VHL, TRC8, and JAB1 appear to be linked both physically and functionally and all three may participate in the development of kidney cancer.

While disturbed energy metabolism in ACC might reflect a common pathology in patients with OCD regardless of symptom dimension, alterations in mesiotemporal lobe are more likely for autogenous obsessions.