Expression of metanephric nephron-patterning genes in differentiating mesonephric tubules.

The metanephros is the functional organ in adult amniotes while the mesonephros degenerates. However, parallel tubulogenetic events are thought to exist between mesonephros and metanephros. Mesonephric tubules are retained in males and differentiate into efferent ducts of the male reproductive tract. By examining the murine mesonephric expression of markers of distinct stages and regions of metanephric nephrons during tubule formation and patterning, we provide further evidence to support this common morphogenetic mechanism. Renal vesicle, early proximal and distal tubule, loop of Henle, and renal corpuscle genes were expressed by mesonephric tubules. Vip, Slc6a20b, and Slc18a1 were male-specific. In contrast, mining of the GUDMAP database identified candidate late mesonephros-specific genes, 10 of which were restricted to the male. Among the male-specific genes are candidates for regulating ion/fluid balance within the efferent ducts, thereby regulating sperm maturation and genes marking tubule-associated neurons potentially critical for normal male reproductive tract function.

Characterisation of Crim1 expression in the developing mouse urogenital tract reveals a sexually dimorphic gonadal expression pattern.

The Crim1 gene encodes a putative transmembrane protein with an IGF-binding protein motif and multiple chordin-like cysteine-rich repeats. In chordin, such repeats are responsible for its dorsalising activity and for binding to bone morphogenic proteins (BMPs). Crim1 displays a dynamic expression pattern in a variety of developing organs, including the CNS and the lens. We have undertaken a detailed expression pattern analysis of Crim1 in the developing mouse urogenital system. During metanephric development, Crim1 showed expression both in the ureteric tree, the early condensing mesenchyme and distal comma-shaped bodies. As the nephron elongates, Crim1 becomes expressed in the proximal end of the S-shaped bodies. Crim1 also displays a striking male-specific expression pattern in the fetal gonads, its expression strongest in the Sertoli cells of the developing testis.

Expression of the vertebrate Slit gene family and their putative receptors, the Robo genes, in the developing murine kidney.

The slit (sli) gene, encoding a secreted glycoprotein, has been demonstrated to play a vital role in axonal guidance in Drosophila melanogaster by acting as a signalling ligand for the robo receptor (Rothberg, J.M., Jacobs, J.R., Goodman, C.S., Artavanis-Tsakonas, S., 1990. slit: an extracellular protein necessary for development of midline glia and commissural axon pathways contains both EGF and LRR domains. Genes Dev. 4, 2169-2187; Kidd, T., Bland, K.S., Goodman, C. S., 1999. Slit is the midline repellent for the robo receptor in Drosophila. Cell 96, 785-794). Multiple homologs of both sli and robo have been identified in vertebrates and are thought to play similar roles to their fly counterparts in neural development (Brose, K., Bland, K.S., Wang, K.H., Arnott, D., Henzel, W., Goodman, C.S., Tessier-Lavigne, M., Kidd, T., 1999. Slit proteins bind Robo receptors and have an evolutionarily conserved role in repulsive axon guidance. Cell 96, 795-806). Slit2 has been shown to bind Robo1, mediating both neuronal and axonal guidance in the developing central nervous system (CNS), (Brose et al., 1999; Hu, H., 1999. Chemorepulsion of neuronal migration by Slit2 in the developing mammalian forebrain. Neuron 23, 703-711). Importantly, both gene families display distinct expression patterns outside the CNS (Holmes, G.P., Negus, K., Burridge, L., Raman, S., Algar, E., Yamada, T., Little, M.H., 1998. Distinct but overlapping expression patterns of two vertebrate slit homologs implies functional roles in CNS development and organogenesis. Mech. Dev. 79, 57-72; Yuan, W., Zhou, L., Chen, J.H., Wu, J.Y., Rao, Y., Ornitz, D.M., 1999. The mouse SLIT family: secreted ligands for ROBO expressed in patterns that suggest a role in morphogenesis and axon guidance. Dev. Biol. 212, 290-306). Using in situ hybridization on metanephric explant cultures and urogenital tract sections, the expression patterns of Slit1, 2, 3 and Robo1 and 2 were investigated during murine metanephric development. Slit1 was expressed in the metanephric mesenchyme (MM) surrounding the invading ureteric tree (UT). Slit2 was expressed at the tips of the UT and both Slit2 and Slit3 were expressed at the far proximal end of the comma shaped and S-shaped bodies. Expression of Robo1 was initially diffuse throughout the MM, then upregulated in the pretubular aggregates, and maintained at the distal end of the comma and S-shaped bodies. Robo2 was detected in the induced MM surrounding the arborizing UT tips and later in the proximal end of the S-shaped bodies. Coincident expression of Robo1 with Slit1 in the metanephric mesenchyme and Robo2, Slit2 and Slit3 in the far proximal end of the S-shaped bodies was observed during metanephric development.

The spectrum of patched mutations in a collection of Australian basal cell carcinomas.

Inactivating mutations in the human patched (PTCH) gene have been identified in both familial and sporadic basal cell carcinomas (BCCs). In some tumors mutations have been detected in both alleles thereby supporting the role of PTCH as a tumor suppressor gene. We have analyzed 22/23 coding exons of PTCH for mutations in 44 sporadic BCCs, and detected 10 novel mutations in nine tumors. In two of the mutant tumors the remaining allele was inactivated by loss of heterozygosity. Five novel PTCH polymorphisms were also identified. Most of the variations found were C>T substitutions at dipyrimidine sites, supporting previous studies which indicate a role for ultraviolet-B in the genesis of sporadic BCCs.

Fine mapping of the neurally expressed gene SOX14 to human 3q23, relative to three congenital diseases.

Members of the Sox gene family encode transcription factors that have diverse and important functions during development. We have recently described the cloning of chick and mouse Sox14 and the expression of these genes in a population of ventral interneurons in the embryonic spinal cord. We report here the cloning and sequencing of the human orthologue of Sox14. Human SOX14 shows remarkable sequence conservation compared with orthologues from other vertebrate species and probably mirrors the expression of these genes in the developing brain and spinal cord. Using radiation hybrid mapping and fluorescence in situ hybridisation, we have localised SOX14 close to the sequence tagged site D3S1576 on human chromosome 3q23. Three congenital disorders have been localised to this region: blepharophimosis-ptosis-epicanthus inversus syndrome (BPES), Charcot-Marie-Tooth neuropathy type IIB (CMT2B) and Mobius syndrome type 2 (MBS2). We have found that SOX14 is unlikely to be involved in any of these disorders because of the position of SOX14 proximal to a BPES breakpoint and the lack of SOX14 coding region alterations in BPES, CMT2B and MBS2 patients.

CRIM1, a novel gene encoding a cysteine-rich repeat protein, is developmentally regulated and implicated in vertebrate CNS development and organogenesis.

Development of the vertebrate central nervous system is thought to be controlled by intricate cell-cell interactions and spatio-temporally regulated gene expressions. The details of these processes are still not fully understood. We have isolated a novel vertebrate gene, CRIM1/Crim1, in human and mouse. Human CRIM1 maps to chromosome 2p21 close to the Spastic Paraplegia 4 locus. Crim1 is expressed in the notochord, somites, floor plate, early motor neurons and interneuron subpopulations within the developing spinal cord. CRIM1 appears to be evolutionarily conserved and encodes a putative transmembrane protein containing an IGF-binding protein motif and multiple cysteine-rich repeats similar to those in the BMP-associating chordin and sog proteins. Our results suggest a role for CRIM1/Crim1 in CNS development possibly via growth factor binding.

Periodontal status of HIV-1 and HIV-2 seropositive and HIV seronegative female commercial sex workers in Senegal.

Comprehensive studies of 92 commercial sex workers in Senegal, Africa included an oral examination in which we obtained measurements of decayed, missing, and filled (DMF) teeth; plaque index; gingival index; recession; probing depth (PD); clinical attachment loss (CAL); and the presence of HIV-associated periodontal lesions, under conditions wherein the examiner was unaware of the subject's HIV status. Twenty-seven subjects (29%) were HIV seropositive, 19 of whom were positive for HIV-1, 7 positive for HIV-2, and 1 positive for both. Most subjects were not taking any medications and previous dental care was limited. HIV-seronegative and HIV-seropositive subjects were similar in mean age, number of DMF teeth, percentage of sites with visible plaque, and number of sites with recession. However, the frequency of sites with gingival bleeding, with PD > or = 6 mm, and with CAL > or = 6 mm was significantly greater in seropositive than seronegative subjects. No differences were observed between HIV-1 and HIV-2 positive subjects. About 26% of HIV-seropositive subjects and about 5% of the seronegative subjects exhibited at least one site with concurrent PD > or = 6 mm and CAL > or = 6 mm. HIV-associated periodontal lesions were seen in 3 HIV-seropositive subjects (2 linear gingival erythema, 1 necrotizing periodontitis). One HIV-seronegative subject exhibited necrotizing gingivitis. In this population with multiple risks to oral health, both HIV-1 and HIV-2 infections were associated with a significantly increased prevalence of periodontal disease.