nr0b1 (DAX1) loss of function in zebrafish causes hypothalamic defects via abnormal progenitor proliferation and differentiation

Ap4s1 truncation leads to axonal defects in a zebrafish model of spastic paraplegia 52

Biallelic mutations in AP4S1, the σ4 subunit of the adaptor protein complex 4 (AP-4), lead to autosomal recessive spastic paraplegia 52 (SPG52). It is a subtype of AP-4-associated hereditary spastic paraplegia (AP-4-HSP), a complex childhood-onset neurogenetic disease characterized by progressive spastic paraplegia of the lower limbs. This disease has so far lacked effective treatment, in part due to a lack of suitable animal models. Here, we used CRISPR/Cas9 technology to generate a truncation mutation in the ap4s1 gene in zebrafish. The ap4s1 truncation led to motor impairment, delayed neurodevelopment, and distal axonal degeneration. This animal model is useful for further research into AP-4 and AP-4-HSP.

Nuclear receptor superfamily structural diversity in pacific oyster: In silico identification of estradiol binding candidates

The increasing presence of anthropogenic contaminants in aquatic environments poses challenges for species inhabiting contaminated sites. Due to their structural binding characteristics to ligands that inhibit or activate gene transcription, these xenobiotic compounds frequently target the nuclear receptor superfamily. The present work aims to understand the potential interaction between the hormone 17-β-estradiol, an environmental contaminant, and the nuclear receptors of Crassostrea gigas, the Pacific oyster. This filter-feeding, sessile oyster species is subject to environmental changes and exposure to contaminants. In the Pacific oyster, the estrogen-binding nuclear receptor is not able to bind this hormone as it does in vertebrates. However, another receptor may exhibit responsiveness to estrogen-like molecules and derivatives. We employed high-performance in silico methodologies, including three-dimensional modeling, molecular docking and atomistic molecular dynamics to identify likely binding candidates with the target moecule. Our approach revealed that among the C. gigas nuclear receptor superfamily, candidates with the most favorable interaction with the molecule of interest belonged to the NR1D, NR1H, NR1P, NR2E, NHR42, and NR0B groups. Interestingly, NR1H and NR0B were associated with planktonic/larval life cycle stages, while NR1P, NR2E, and NR0B were associated with sessile/adult life stages. The application of this computational methodological strategy demonstrated high performance in the virtual screening of candidates for binding with the target xenobiotic molecule and can be employed in other studies in the field of ecotoxicology in non-model organisms.

Expression and Transcript Localization of star, sf-1, and dax-1 in the Early Brain of the Orange-Spotted Grouper Epinephelus coioides

We investigated the developmental expression and localization of sf-1 and dax-1 transcripts in the brain of the juvenile orange-spotted grouper in response to steroidogenic enzyme gene at various developmental ages in relation to gonadal sex differentiation. The sf-1 transcripts were significantly higher from 110-dah (day after hatching) and gradually increased up to 150-dah. The dax-1 mRNA, on the other hand, showed a decreased expression during this period, in contrast to sf-1 expression. At the same time, the early brain had increased levels of steroidogenic gene (star). sf-1 and star hybridization signals were found to be increased in the ventromedial hypothalamus at 110-dah; however, dax-1 mRNA signals decreased in the early brain toward 150-dah. Furthermore, the exogenous estradiol upregulated star and sf-1 transcripts in the early brain of the grouper. These findings suggest that sf-1 and dax-1 may have an antagonistic expression pattern in the early brain during gonadal sex differentiation. Increased expression of steroidogenic gene together with sf-1 during gonadal differentiation strongly suggests that sf-1 may play an important role in the juvenile grouper brain steroidogenesis and brain development.