The Wilms Tumor Gene wt1a Contributes to Blood-Cerebrospinal Fluid Barrier Function in Zebrafish

The Wilms tumor suppressor gene Wt1 encodes a zinc finger transcription factor, which is highly conserved among vertebrates. It is a key regulator of urogenital development and homeostasis but also plays a role in other organs including the spleen and the heart. More recently additional functions for Wt1 in the mammalian central nervous system have been described. In contrast to mammals, bony fish possess two paralogous Wt1 genes, namely wt1a and wt1b. By performing detailed in situ hybridization analyses during zebrafish development, we discovered new expression domains for wt1a in the dorsal hindbrain, the caudal medulla and the spinal cord. Marker analysis identified wt1a expressing cells of the dorsal hindbrain as ependymal cells of the choroid plexus in the myelencephalic ventricle. The choroid plexus acts as a blood-cerebrospinal fluid barrier and thus is crucial for brain homeostasis. By employing wt1a mutant larvae and a dye accumulation assay with fluorescent tracers we demonstrate that Wt1a is required for proper choroid plexus formation and function. Thus, Wt1a contributes to the barrier properties of the choroid plexus in zebrafish, revealing an unexpected role for Wt1 in the zebrafish brain.

Siblings with Imperforate anus and aplastic nasal alae: Johanson-Blizzard syndrome

Johanson-Blizzard syndrome is a rare genetic entity reported in medical literature resulting from mutations in UBR1 gene, affecting pancreas, craniofacial and urogenital development, causing significant morbidity and mortality. We report a neonate presenting with anorectal malformation requiring surgical intervention at birth, with similar surgeries being performed in two elder siblings. Surviving sibling of the proband neonate also has similar dysmorphic features of absent ala nasi, aplasia cutis of scalp along with pancreatic insufficiency, profound sensorineural hearing loss, pheno-type corresponding to Johanson-Blizzard syndrome. Syndromic diagnosis helps in screening for associated potential issues, which can intervened at early stages.

Alternative splicing and thermosensitive expression of Dmrt1 during urogenital development in the painted turtle, Chrysemys picta

Background The doublesex and mab-3 related transcription factor 1 (Dmrt1) is a highly conserved gene across numerous vertebrates and invertebrates in sequence and function. Small aminoacid changes in Dmrt1 are associated with turnovers in sex determination in reptiles. Dmrt1 is upregulated in males during gonadal development in many species, including the painted turtle, Chrysemys picta, a reptile with temperature-dependent sex determination (TSD). Dmrt1 is reported to play different roles during sex determination and differentiation, yet whether these functions are controlled by distinct Dmrt1 spliceoforms remains unclear. While Dmrt1 isoforms have been characterized in various vertebrates, no study has investigated their existence in any turtle. Methods We examine the painted turtle to identify novel Dmrt1 isoforms that may be present during urogenital development using PCR, profile their expression by RNA-seq across five embryonic stages at male- and female-producing temperatures, and validate their expression pattern via qPCR with transcript-specific fluorescent probes. Results A novel Dmrt1 spliceoform was discovered for the first time in chelonians, lacking exons 2 and 3 (Dmrt1 ΔEx2Ex3). Dmrt1 canonical and ΔEx2Ex3 transcripts were differentialy expressed by temperature at stages 19 and 22 in developing gonads of painted turtles, after the onset of sex determination, and displayed a significant male-biased expression pattern. This transcriptional pattern differs from studies in other turtles and vertebrates that reported Dmrt1 differential expression before or at the onset of sex determination. This study provides the first insight into Dmrt1 transcriptional diversity in turtles and opens the door for future functional studies of the alternative Dmrt1 transcript uncovered here. Conclusions The discovery of an isoform in turtles indicate that alternative splicing may be a common feature of Dmrt1 across vertebrates, as isoforms are also found in crocodilians, birds, mammals and fish, and this variation remains unexplained. The relatively late-onset of Dmrt1 expression observed here contrasts with other turtles, indicating that Dmrt1 is not the topmost male sex -determining factor in C. picta. When placed in a phylogenetic context, this discrepancy underscores the divergent regulation of Dmrt1, and of sexual development more generally, across vertebrates.

Primary Amenorrhea, Aplastic Uterus, and a Functional Vagina: A Rare Case of Mayer-Rokitansky-Küster-Hauser Syndrome

Background. Müllerian agenesis, also known as Mayer-Rokitansky-Küster-Hauser syndrome (MRKHS), a failure of female urogenital development, typically results in a completely stenotic or rudimentary dimple vagina, both of which are generally nonfunctional in adulthood without mechanical dilation or surgical reconstruction. Case. A 20-year-old Tanner stage V heterosexual woman with normal sexual function since coitarche presented with a chief complaint of primary amenorrhea. She was found to have aplastic uterine buds, absent endometrium/cervix, normal ovaries, and an unusually well-developed lower vagina, a rare presentation of MRKHS. We discuss mechanisms by which the anomaly may have arisen. Summary & Conclusion. This case thus expands the clinical presentation of MRKHS to include a normal appearing vagina with intact sexual function from first sexual encounter, raising interesting questions about the basic underlying embryology.