Anti-DLL1 Monoclonal antibody, Alexa Fluor® 488

BACKGROUND: The objective of the current study was to characterize the morphological and genetic basis of cryptorchidism. METHODS AND RESULTS: We investigated cryptorchidism in LH receptor (Lhr) knockout (LhrKO) mice and how testosterone-replacement therapy (TRT) worked to correct the phenotype. The results revealed that while gubernacular development was indistinguishable between Lhr-null and wild-type animals until 7 days of age, it was subsequently severely impaired in null animals. This was due to a reduction in mesenchymal cell division, differentiation into cremaster muscle cells and their delayed maturation. While transcript levels of Hoxa10, Hoxa11, Desrt and Dll1 were indistinguishable, the levels of Notch1, Numb and Lgr8 in the gubernaculum and Insl3 in the testes were lower in Lhr-null than in wild-type siblings. The TRT, which completed testicular descent into the scrotum, corrected the morphological changes and the expression of Lgr8, Numb and Notch, but not Insl3, to wild-type levels. Transection of the genitofemoral nerve did not prevent the TRT effect. CONCLUSION: In summary, cryptorchidism in Lhr-null animals was caused by defects in the gubernacular development due to testosterone deficiency. TRT reversed all the morphological and gene expression changes except Insl3, suggesting that testosterone, not INSL3, secreted by Leydig cells, facilitates the completion of testicular descent.

The Notch signaling pathway has pleiotropic functions during mammalian embryogenesis. It is required for the patterning and differentiation of the presomitic and somitic paraxial mesoderm and of the neural tube. We used DNA-chip expression profiling and 2D-gel electrophoresis combined with peptide mass fingerprinting to identify genes and proteins differentially regulated in E10.5 Dll1 (delta-like 1, Delta1) mutant embryos. The differential expression profiling approach identified 47 regulated transcripts and 40 differentially expressed proteins. The majority of these genes has until now not been associated with Notch signaling. Subsequent whole-mount in situ hybridization confirmed that a subset of the identified transcripts has restricted and distinct patterns of expression in E10.5 mouse embryos. For most genes these expression patterns were affected in the presomitic mesoderm, in differentiating somites of Dll1 mutant embryos and in the neural tube and cells differentiating from it. Similar effects were observed in embryos homozygous for the Headturner (Htu) and pudgy (pu) mutations, which are alleles of the Notch ligands Jag1 and Dll3. The regulated expression of a subset of the proteins was validated by immunoblots. Remarkably six of the proteins down-regulated in Dll1 mutant embryos are proteasome subunits. The large set of regulated genes identified in this differential expression profiling approach is an important resource for further functional studies. (c) 2005 Elsevier B.V. All rights reserved.