Biology subjects

Fernandino, J. I.

Publications and source records attributed to Fernandino, J. I..

4 recordsLinked to original sources

bioRxiv2021

Notch pathway is required for protection against heat-stress in spermatogonial stem cells

Environmentally favorable conditions the sustainability of spermatogenesis is brought about by a balance between two types of division, the self-renewal division for the maintenance of the stem cell pool and the differentiation division for continuous production of spermatozoa. The production of gametes under unfavorable, stressful conditions can decrease or even be interrupted, compromising fertility parameters. Thus, the survival of spermatogonial stem cells (SSCs) is crucial for the recovery of spermatogenesis after stressful situations (e.g. high temperature). Here, we show that the Notch pathway protects the spermatogonial stem cells against thermal stress, ensuring reproductive success after normal conditions are restored. First, presenilin enhancer-2 (pen-2), the catalytic subunit of {gamma}-secretase complex, was localized in SSCs of the medaka testis. The exposure of adult males to thermal stress condition induced apoptosis in all spermatogenics cells, with the exception of SSCs. Concomitantly, the Notch pathways was up-regulated, including the pen-2, its ligands (dll4, jag1-2) and its receptors (notch1a-3); pen-2 expression was restricted to the SSCs during thermal stress. The importance of this pathway was further supported by an ex vivo approach, in which the inhibition of Notch activity induced a loss of SSCs. Overall, this study demonstrates that the Notch pathways activity is necessary for the protection of SSCs under chronic thermal stress.

cell biology↗

bioRxiv2021

Non-invasive sex genotyping of paiche Arapaima gigas by qPCR: An applied bioinformatic approach to identify sex differences

Arapaima gigas, one of the largest freshwater fish in the world, is suffering from high fishing pressure and habitat loss, which threaten the conservation status of its natural populations. Of great cultural importance to Amazonian people, the paiche or pirarucu A. gigas is in high demand for its meat, ornamental uses and other byproducts such as scales. Aquaculture is a feasible solution to this dilemma. However, the fact that A. gigas presents no sexual dimorphism until it is 5 years old and its long period to sexual maturity are major obstacles for brood-stock management and fingerling production. Thus, the aim of this study was to develop a molecular tool for non-invasive genotypic sexing of paiche throughout its life cycle. We collected samples from gonads, fins and gill mucus of juvenile specimens from local facilities for histological and molecular analysis. Based on the recently available genome sequence of the paiche and making use of current NGS method, we implemented a novel approach, called Genome Differences by Unmapped Reads, to identify DNA sex markers. We found a Male-Specific Region (MSR), identified as MSR_3728, to be present only in males. Next, we designed two specific sets of primers on this region to identify genotypic sex by qPCR assays. Both primer sets, MSR_107 and MSR_129, detected males with 100% accuracy. Then we developed a duplex qPCR reaction for each primer set along a reference gene, analyzed the melting curves and detected males by observing two distinct peaks, one for MSR_107 or MSR_129 and one for the reference, while females only presented the reference peak. The same results were obtained for gonads, fins and interestingly, a non-invasive source from gill mucus samples. Finally, the gonads were evaluated histologically in a double-blind test, showing 100% accuracy with qPCR assay for identifying males and females. Data clearly demonstrated a novel pipeline approach for identifying DNA sex markers, followed by a quick, non-invasive, cost-effective duplex qPCR method for sexing A. gigas. These results may be valuable to efficient paiche aquaculture and conservation studies, helping to reduce the fishing pressure on its natural populations. Highlights of the manuscript- Implementation of a novel approach, called Genome Differences by Unmapped Reads, to identify DNA sex markers. - Finding of a Male-Specific Region (MSR), present only in males. - Development of a duplex qPCR to identify genotypic sex through non-invasive sampling.

genomics↗

bioRxiv2020

Cystic proliferation of embryonic germ stem cells is necessary to reproductive success and normal mating behavior in medaka

The production of an adequate number of gametes in both sexes is necessary for normal reproduction, for which the regulation of proliferation from early gonadal development to adulthood is key. Cystic proliferation of embryonic stem germ cells prior the onset of gametogenesis is an especially important step prior to the beginning of meiosis. However, in vertebrates, the molecular regulators of cystic proliferation remain unknown. Here, we report that ndrg1b, a member of the N-myc downstream regulated family, is an important regulator of cystic proliferation in medaka. We generated mutants of ndrg1b that led to a disruption of proliferation type II, independently of the TGF-{beta} signaling pathway. This loss of cystic proliferation was observed from embryogenic to adult stages, impacting the success of gamete production and reproductive parameters such as spawning and fertilization. Interestingly, the depletion of cystic proliferation of the ndrg1b mutant also impacted male sexual behavior, with a decrease of mating vigor. These data illustrate why it is also necessary to consider gamete production capacity in order to analyze reproductive behavior. HIGHLIGHTSO_LINdrg1b is involved in the regulation of cystic proliferation in gonad from embryo to adulthood. C_LIO_LIThe cystic proliferation is independently of the TGF-{beta} signaling pathway. C_LIO_LIDecrease of production of gametes declines reproductive success for both sexes. C_LIO_LIReduction of cystic proliferation declines male sexual behavior, with a decrease of mating vigor. C_LI

developmental biology↗

bioRxiv2020

Morphological colour adaptation during development: Involvement of Growth Hormone Receptor 1

Morphological background adaptation is both an endocrine and a nervous response, involving changes in the amount and shape of chromatophores. However, if this adaptation takes place at early developmental stages is largely unknown. Somatolactin (SL) is a pituitary hormone present in fish, which has been associated to skin pigmentation. Moreover, growth hormone receptor type 1 (ghr1) has been suggested to be the SL receptor and was associated to background adaptation in adults. In this context, the aim of this work was to evaluate the ontogeny of morphological adaptation to background and the participation of ghr1 in this process. We found in larval stages of Cichlasoma dimerus that the number of head melanophores and ir-SL pituitary cells were increased in individuals reared in black backgrounds compared to fish grown in white tanks. In medaka (Oryzias latipes) larval stages a similar response was observed that is altered by a ghr1 biallelic mutations using CRISPR/cas9. Interestingly, melanophore and leucophore numbers are highly associated. Furthermore, we found that somatic growth is reduced in ghr1 biallelic mutant medaka, establishing the dual function of this growth hormone receptor. Taken together, these results show that morphological background adaptation is present at early stages during development and that is dependent upon ghr1 unless during this period.

developmental biology↗