Biology subjects

Butzge, A. J.

Publications and source records attributed to Butzge, A. J..

3 recordsLinked to original sources

bioRxiv2024

De novo assembly and characterization of a highly degenerated ZW sex chromosome in the fish Megaleporinus macrocephalus

BackgroundMegaleporinus macrocephalus (piaucu) is a Neotropical fish within Characoidei that presents a well-established heteromorphic ZZ/ZW sex-determination system and thus, constitutes a good model for studying W and Z chromosomes in fishes. We used PacBio reads and Hi-C to assemble a chromosome-level reference genome for M. macrocephalus. We generated family segregation information to construct a genetic map, pool-seq of males and females to characterize its sex system, and RNA-seq to highlight candidate genes of M. macrocephalus sex determination. ResultsM. macrocephalus reference genome is 1,282,030,339 bp in length and has a contig and scaffold N50 of 5.0 Mb and 45.03 Mb, respectively. Based on patterns of recombination suppression, coverage, Fst, and sex-specific SNPs, three major regions were distinguished in the sex chromosome: W-specific (highly differentiated), Z-specific (in degeneration), and PAR. The sex chromosome gene repertoire was composed of genes from the TGF-{beta} family (amhr2, bmp7) and Wnt/{beta}-catenin pathway (wnt4, wnt7a), and some of them were differentially expressed. ConclusionsThe chromosome-level genome of piaucu exhibits high quality, establishing a valuable resource for advancing research within the group. Our discoveries offer insights into the evolutionary dynamics of Z and W sex chromosomes in fish, emphasizing ongoing degenerative processes and indicating complex interactions between Z and W sequences in specific genomic regions. Notably, amhr2 and bmp7 are potential candidate genes for sex determination in M. macrocephalus.

genomics↗

bioRxiv2021

Gdnf, a germ cell-derived factor, regulates zebrafish germ cell stemness through the creation of new spermatogonial niches (germ and Sertoli cells) and inhibition of spermatogonial differentiation in an autocrine and paracrine manners

Glial cell line-derived neurotrophic factor (GDNF) and its receptor (GDNF Family Receptor 1 - GFR1) are well known to mediate spermatogonial stem cell (SSC) proliferation and survival in the mammalian testes. In nonmammalian species, Gdnf and Gfr1 orthologs have been found but their functions remain poorly investigated in the testis. Considering this background, this study aimed to understand the roles of Gdnf-Gfr1 signaling pathway in the zebrafish testis by combining in vivo, in silico and ex vivo approaches. Our analysis showed that zebrafish exhibited two paralogs of Gndf (gdnfa and gdnfb) and its receptor, Gfr1 (gfr1a and gfr1b), in agreement with the teleost-specific third round (3R) of whole genome duplication. Expression analysis further revealed that gdnfa and gfr1a were the most expressed copies in the zebrafish adult testes. Subsequently, we demonstrated that gdnfa is expressed in the germ cells, while Gfr1a was detected in early spermatogonia (mainly in types Aund and Adiff) and Sertoli cells. Functional ex vivo analysis showed that Gdnf promoted the creation of new available niches by stimulating proliferation of both type Aund spermatogonia and their surrounding Sertoli cells, but without changing pou5f3 mRNA levels. Strikingly, Gdnf also inhibited late spermatogonial differentiation as shown by the decrease of type B spermatogonia and down-regulation of dazl in the co-treatment with Fsh. Altogether, our data revealed for the first time that a germ cell-derived factor is associated with maintaining germ cell stemness through the creation of new available niches, supporting development of differentiating spermatogonial cysts and inhibiting late spermatogonial differentiation in autocrine and paracrine manners.

cell biology↗

bioRxiv2019

Generation of a white-albino phenotype from cobalt blue and yellow-albino trouts: inheritance pattern and chromatophores analysis

Albinism is the most common color variation described in fish and is characterized by a white or yellow phenotype according to the species. In rainbow trout Oncorhynchus mykiss, aside from yellow-albino phenotypes, cobalt blue variants with autosomal, recessive inheritance have also been reported. In this study, we investigated the inheritance pattern and chromatophores distribution/abundance of cobalt blue trouts obtained from a local fish farm. Based on crosses with wild-type and dominant yellow-albino lines, we could infer that cobalt blue are dominant over wild-type and co-dominant in relation to yellow-albino phenotype, resulting in a fourth phenotype: the white-albino. Analysis of chromatophores revealed that cobalt blue trouts present melanophores, as the wild-type, and a reduced number of xanthophores. As regards to the white-albino phenotype, they were not only devoid of melanophores but also presented a reduced number of xanthophores. Cobalt blue and white-albino trouts also presented a more elongated body shape and, most remarkably, a smaller pituitary gland compared to wild-type and yellow-albino, suggesting that the allele for blue color is somehow linked with this abnormal pituitary phenotype. These phenotypes represent interesting models for research on body pigmentation in salmonids and on the mechanisms behind endocrine control of color patterning.

genetics↗