Biology subjects

Nourizadeh-Lillabadi, R.

Publications and source records attributed to Nourizadeh-Lillabadi, R..

3 recordsLinked to original sources

bioRxiv2021

Ectopic expression of lipid homeostasis genes in rare cells of the teleost pituitary gland

Directing both organismal homeostasis and physiological adaptation, the pituitary is a key endocrine gland in all vertebrates. It communicates the needs of the organism to different organs by secreting hormones into the bloodstream. Here, we have used the model fish medaka to investigate the developmental dynamics in the pituitary using a comprehensive RNA-seq time series. By linking developmental expression trends to single-cell RNA-seq profiles, we show how the transcriptional activities of cell types change during sexual maturation. One of the most prominent changes is the decline of the non-endocrine folliculo-stellate cell populations, and especially of rare cells expressing genes encoding secreted lipid transport proteins. As these genes are typically associated with the liver, this reveals the existence of unexpected connections between endocrine communication, lipid homeostasis, and sexual maturation.

physiology↗

bioRxiv2021

3D atlas of the pituitary gland of the model fish medaka

In vertebrates, the anterior pituitary plays a crucial role in regulating several essential physiological processes via the secretion of at least seven peptide hormones by different endocrine cell types. Comparative and comprehensive knowledge of the spatial distribution of those endocrine cell types is required to better understand their role during the animal life. Using medaka as the model and several combinations of multi-color fluorescence in situ hybridization, we present the first 3D atlas revealing the gland-wide distribution of seven endocrine cell populations: lactotropes, thyrotropes, Lh and Fsh gonadotropes, somatotropes, and pomca-expressing cells (corticotropes and melanotropes) in the anterior pituitary of a teleost fish. By combining in situ hybridization and immunofluorescence techniques, we deciphered the location of corticotropes and melanotropes within the pomca-expressing cell population. The 3D localization approach reveals sexual dimorphism of tshba- and pomca-expressing cells in the adult medaka pituitary. Finally, we show the existence of bi-hormonal cells co-expressing lhb-fshb, fshb-tshba and lhb-sl using single-cell transcriptomics analysis and in situ hybridization. This study offers a solid basis for future comparative studies of the teleost pituitary and its developmental plasticity. Highlights- We offer the first 3D atlas of a teleost pituitary, which presents a valuable resource to the endocrinology and model fish community. - The atlas reveals the 3D spatial distribution of the seven endocrine cell types and blood vessels in the juvenile/adult male and female pituitary. - Gene expression for tshba and pomca, as well as the population size of cells expressing these genes, displays obvious sexual dimorphism in the adult medaka pituitary. - Multi-color in situ hybridization and single cell RNA-seq reveal the existence of bi-hormonal cells, co-expressing lhb-fshb, fshb-tshba, lhb-sl, and a few multi-hormonal cells. - An online version of the atlas is available at https://www.nmbu.no/go/mpg-atlas.

neuroscience↗

bioRxiv2021

Sexual maturation in Atlantic salmon male parr may be triggered both in early spring and late summer under standard farming conditions

Male Atlantic salmon (Salmo salar) display different sexual strategies, maturing either as parr during the freshwater phase (as sneaky spawners), or as post smolts following one or several years at sea. First sexual maturation (puberty) occurs at different times depending on environmental and genetic factors. To improve our knowledge on the timing (age and season) of first sexual maturation in Atlantic salmon male parr, we investigated pubertal activation in second generation farmed salmon from the Norwegian river Figgjo, reared under natural conditions of photoperiod and water temperature. Histological analysis, in combination with morphometric measurements, plasma androgen levels and pituitary gonadotropin gene expression analysis revealed that, as previously reported, some male parr initiated early sexual maturation in spring at one year of age. Interestingly, some male parr were observed to initiate sexual maturation already in autumn, six months after hatching (under-yearlings), much earlier than reported in previous studies. One-year old maturing males showed a low induction in gonadotropin levels, while under-yearling maturing males displayed a significant increase in fshb transcripts as compared to immature fish. Plasma testosterone, detectable also in immature males, increased constantly during testes development, while 11-ketotestosterone, undetectable in immature and early maturing males, increased during more advanced stages of maturation. A mild feminization of the testes (ovotestes) was detected in a subset of samples. This study brings new knowledge on the little investigated field of sexually maturing under-yearlings in Atlantic salmon. This is also the first study comparing the physiology of under-yearling vs one-year old maturing male parr, thus bringing new insights to the remarkable plasticity of Atlantic salmon puberty.

physiology↗