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Supplementary materials for "Sexually dimorphic regulation of gonadotrope cell hyperplasia in medaka pituitary via mitosis and transdifferentiation"
No full textThis file is a supplementary figures for the manuscript "Sexually dimorphic regulation of gonadotrope cell hyperplasia in medaka pituitary via mitosis and transdifferentiation"The two pituitary gonadotropins, Fsh and Lh, regulate the reproductive function in vertebrates. While many studies have investigated the regulation of gonadotropin production and release by the sex steroid feedback, its role on the regulation of gonadotrope cell number remains unclear. Using medaka as a model and an optimized protocol to restore physiological sex steroids levels following gonadectomy, we show that gonadal sex steroids not only decrease fshb transcript levels, but also Fsh cell number in both sexes. We then investigated the origin of the Fsh cell hyperplasia induced by gonadectomy. In both sexes, BrdU incubation shows that this is achieved via Fsh cell mitosis. In situ hybridization reveals that new Fsh cells also originate from transdifferentiating Tsh cells in females, but not in males. Both phenomena are inhibited by sex steroid supplementation via feeding. In males (but not females), gonadectomy (without recovery with sex steroid supplementation) also reduces sox2 transcript levels and Sox2-immunopositive population volume, suggesting that sox2-progenitors may be recruited to produce new Fsh cells. Opposite to Fsh cells, gonadectomy decreases lhb levels in both sexes, and levels are not restored by sex steroid supplementation. In addition, the regulation of Lh cell number also seems to be sex dependent. Removal of gonadal sex steroids stimulates Lh cell mitosis in male (like Fsh cells), but not in females. To conclude, our study provides the first evidence on sexually dimorphic mechanisms used in the fish pituitary to remodel gonadotrope populations in response to sex steroids
Replication Data for: 3D atlas of the pituitary gland of the model fish medaka (Oryzias latipes)
No full textThe imaging files are the supplementary figures for paper entitled "3D atlas of the pituitary gland of the model fish medaka". The files are hyperstack TIFF files images showing channels corresponding to endocrine cell markers, including blood vessels, in the pituitary of juvenile and adult male and female medaka
Direct and Indirect Effects of Sex Steroids on Gonadotrope Cell Plasticity in the Teleost Fish Pituitary
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Fotoperiode og kjønnsteroiders regulering av hypofysens gonadotroper i medaka
No full textTo adapt to the changing physiological states throughout the reproductive cycle, the pituitary needs to fine-tune the production and secretion of gonadotropin hormones (FSH and LH), which regulate gonadal maturation. Until now, many studies have investigated how the pituitary adjusts gonadotropin production at the transcript and protein levels, but little is known about how the number of gonadotropes is regulated. Therefore, in this thesis, I used a teleost fish, the Japanese medaka (Oryzias latipes), as the model to investigate the regulation of gonadotrope cell number, with emphasis on the effect of sex steroids and photoperiod.
First, I developed a 3D atlas of all seven endocrine cell types in the medaka pituitary. I found a consistency between transcript levels and cell population size in some cell types, indicating that differences in hormone production are not only due to changes in cell activity, but also in cell number. Identification of bi-hormonal cells suggests phenotypic plasticity between some endocrine cell types, potentially contributing to increasing hormone production when needed. Second, I optimized a sex steroid supplementation protocol that I used to demonstrate that gonadal sex steroids inhibit Fsh cell hyperplasia. I showed that in the absence of gonadal sex steroids, Fsh hyperplasia is achieved by mitosis in both sexes. In addition, transdifferentiation of Tsh into Fsh cell contributes to Fsh hyperplasia in females while stem cell differentiation seems to be involved in males.
Finally, I demonstrated a stimulatory effect of long photoperiod (daylight duration) on gonadotrope cell activity and number. I then revealed the existence of a novel intra-pituitary pathway, stimulating gonadotrope cell activity and proliferation in the female medaka, which involves melatonin, Tsh, and folliculostellate cells. Taken together, my findings reveal how the medaka pituitary adapts to a changing environment and physiological needs by remodelling gonadotrope cell number to fine-tune gonadotropin production. These results also shed light on new regulatory mechanisms and pathways for pituitary plasticity that may be shared among other vertebrates.For å tilpasse seg de fysiologiske endringene gjennom reproduksjonssyklus og kjønnsmodning, må hypofysen finjustere produksjonen og utskillelsen av gonadotropinhormoner (FSH og LH). Til nå har mange studier undersøkt hvordan hypofysen justerer gonadotropinproduksjonen på transkripsjons- og proteinnivå, men lite er kjent om hvordan antall gonadotropinproduserende celler(gonadotrofer) reguleres. Derfor brukte jeg i dette arbeidet en teleostfisk, den japanske medaka (Oryzias latipes), som modell for å undersøke reguleringen av gonadotroper cellenummer, med vekt på effekten av kjønnssteroider og fotoperiode.
Først utviklet jeg et 3D-atlas over alle de syv endokrine celletypene i medakahypofysen. Jeg fant et samsvar mellom transkripsjonsnivåer og cellepopulasjonsstørrelse i noen celletyper, noe som indikerer at forskjeller i hormonproduksjon ikke bare skyldes endringer i celleaktivitet, men også i celleantall. Identifisering av celler som kunne produsere to forskjellige hormoner antyder fenotypisk plastisitet mellom noen endokrine celletyper, som potensielt kan bidra til å øke hormonproduksjonen når det er nødvendig.
Deretter optimaliserte jeg en protokoll for tilførsel av kjønnssteroider som jeg brukte til å demonstrere at slike steroider hemmer Fsh-cellehyperplasi. Jeg viste at i fravær av kjønnssteroider, oppnås Fsh-cellehyperplasi ved mitose hos begge kjønn. I tillegg bidrar transdifferensiering av Tsh-celler til Fsh-celler også til Fshcellehyperplasi hos hunnfisk, mens stamcelledifferensiering ser ut til å være involvert hos hannfisk. Til slutt demonstrerte jeg en stimulerende effekt av lang fotoperiode (dagslysvarighet) på gonadotropaktivitet og -antall. Jeg oppdaget også en ny intrahypofysær signalvei, som stimulerer gonadotropaktivitet og -spredning hos hunnmedaka, og som involverer melatonin, Tsh og follikulostellatceller. Samlet sett viser funnene mine hvordan medaka-hypofysen tilpasser seg skiftende miljø og fysiologiske behov ved å omstille gonadotroper cellenummer for å finjustere gonadotropinproduksjonen. Disse resultatene kaster også lys over nye reguleringsmekanismer og signalveier for hypofyseplastisitet som kan være viktige også hos andre virveldyr
A comparative study of chronic stressors effectivity on the stress response of Atlantic salmon (Salmo salar L.) post-smolt
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Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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