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The Müllerian ducts are part of the embryonic urogenital system. They give rise to mature structures that serve a critical function in the transport and development of the oocyte and/or embryo. In most vertebrates, both sexes initially develop Müllerian ducts during embryogenesis, but they regress in males under the influence of testis-derived Anti-Müllerian Hormone (AMH). A number of regulatory factors have been shown to be essential for proper duct development, including Bmp and Wnt signaling molecules, together with homeodomain transcription factors such as PAX2 and LIM1. Later in development, the fate of the ducts diverges between males and females and is regulated by AMH and Wnt signaling molecules (duct regression in males) and Hox genes (duct patterning in females). Most of the genes and molecular pathways known to be involved in Müllerian duct development have been elucidated through animal models, namely, the mouse and chicken. In addition, genetic analysis of humans with reproductive tract disorders has further defined molecular mechanisms of duct formation and differentiation. However, despite our current understanding of Müllerian duct development, some questions remain to be answered at the molecular genetic level. This article is categorized under: Early Embryonic Development > Development to the Basic Body Plan.

Background Müllerian ducts are paired embryonic tubes that give rise to the female reproductive tract in vertebrates. Many disorders of female reproduction can be attributed to anomalies of Müllerian duct development. However, the molecular genetics of Müllerian duct formation is poorly understood and most disorders of duct development have unknown etiology. In this study, we describe for the first time the transcriptional landscape of the embryonic Müllerian duct, using the chicken embryo as a model system. RNA sequencing was conducted at 1 day intervals during duct formation to identify developmentally-regulated genes, validated by in situ hybridization. Results This analysis detected hundreds of genes specifically up-regulated during duct morphogenesis. Gene ontology and pathway analysis revealed enrichment for developmental pathways associated with cell adhesion, cell migration and proliferation, ERK and WNT signaling, and, interestingly, axonal guidance. The latter included factors linked to neuronal cell migration or axonal outgrowth, such as Ephrin B2, netrin receptor, SLIT1 and class A semaphorins. A number of transcriptional modules were identified that centred around key hub genes specifying matrix-associated signaling factors; SPOCK1, HTRA3 and ADGRD1. Several novel regulators of the WNT and TFG-β signaling pathway were identified in Müllerian ducts, including APCDD1 and DKK1, BMP3 and TGFBI. A number of novel transcription factors were also identified, including OSR1, FOXE1, PRICKLE1, TSHZ3 and SMARCA2. In addition, over 100 long non-coding RNAs (lncRNAs) were expressed during duct formation. Conclusions This study provides a rich resource of new candidate genes for Müllerian duct development and its disorders. It also sheds light on the molecular pathways engaged during tubulogenesis, a fundamental process in embryonic development.

The embryonic Müllerian ducts give rise to the female reproductive tract (fallopian tubes, uterus and upper vagina in humans, the oviducts in birds). Embryonic Müllerian ducts initially develop in both sexes, but later regress in males under the influence of anti-Müllerian hormone. While the molecular and endocrine control of duct regression in males have been well studied, early development of the ducts in both sexes is less well understood. Here, we describe a novel role for the adhesion G protein-coupled receptor, GPR56, in development of the Müllerian ducts in the chicken embryo. GPR56 is expressed in the ducts of both sexes from early stages. The mRNA is present during the elongation phase of duct formation, and it is restricted to the inner Müllerian duct epithelium. The putative ligand, Collagen III, is abundantly expressed in the Müllerian duct at the same developmental stages. Knockdown of GPR56 expression using in ovo electroporation results in variably truncated ducts, with a loss of expression of both epithelial and mesenchymal markers of duct development. Over-expression of GPR56 in vitro results in enhanced cell proliferation and cell migration. These results show that GPR56 plays an essential role in avian Müllerian duct development through the regulation of duct elongation.

At present there is no well structured database available for the venomous snakes and venom composition of snakes in the world although venom has immense importance in biomedical research. Searching for a specific venom component from NCBI, PDB or public databases is troublesome, because they contain huge amount of data entries. Therefore, we created a database named “ISOB” which is a web accessible unique secondary database that represents the first online available bioinformatics resource showing venom composition of snakes. This database provides a comprehensive overview of seventy-eight indigenous snake species covering description of snakes supplemented with structural information of the relevant individual available venom proteins. We strongly believe that this database will contribute significantly in the field of bioinformatics, environmental research, proteomics, drug development and rationale drug designing.AvailabilityThe database is freely available at http://www.snakebd.com/