Biology subjects

Ferreira, L.

Publications and source records attributed to Ferreira, L..

23 records · Page 2Linked to original sources

bioRxiv2021

The structural and electrophysiological properties of progesterone receptor expressing neurons vary along the anterior-posterior axis of the ventromedial hypothalamus and undergo local changes across the reproductive cycle

Sex hormone levels continuously fluctuate across the reproductive cycle, changing the activity of neuronal circuits to coordinate female behavior and reproductive capacity. The ventrolateral division of the ventromedial hypothalamus (VMHvl) contains neurons expressing receptors for sex hormones and its function is intimately linked to female sexual receptivity. However, recent findings suggest that the VMHvl is functionally heterogeneous. Here, we used whole cell recordings and intracellular labeling to characterize the electrophysiological and morphological properties of individual VMHvl neurons in naturally cycling females. We found that the properties of progesterone receptor expressing (PR+) neurons, but not PR- neurons, depended systematically on the neurons location along the anterior-posterior axis of the VMHvl and the phase within the reproductive cycle. Prominent amongst this, the resting membrane potential of anterior PR+ neurons decreased during the receptive phase, while the excitability of medial PR+ neurons increased during the non-receptive phase. During the receptive phase of the cycle, posterior PR+ neurons simultaneously showed an increase in dendritic complexity and a decrease in spine density. These findings reveal an extensive diversity of local rules driving structural and physiological changes in response to fluctuating levels of sex hormones, supporting the anatomical and functional subdivision of the VMHvl and its possible role in the orchestration of different aspects of female socio-sexual behavior.

neuroscience↗

bioRxiv2019

Mitotic exit is controlled during anaphase by an Aurora B-Cyclin B1/Cdk1 crosstalk

According to the prevailing \"clock\" model, chromosome decondensation and nuclear envelope reassembly during mitotic exit are byproducts of Cdk1 inactivation at the metaphase-anaphase transition, controlled by the spindle assembly checkpoint. However, mitotic exit was recently shown to be a function of chromosome separation during anaphase, assisted by a midzone Aurora B phosphorylation gradient - the \"ruler\" model. Here we reconciled both models by showing that Cyclin B1 degradation continues during anaphase in Drosophila, mouse and human cells, including primary tissues. This required APC/CCdh1 activity, and failure to degrade Cyclin B1 during anaphase prevented mitotic exit in a Cdk1-dependent manner. Cyclin B1 localization and half-life during anaphase depended on kinesin-6, which targets Aurora B to the spindle midzone. Mechanistically, we show that anaphase duration is regulated by Aurora B-mediated phosphorylation of Cyclin B1. We propose that a crosstalk between molecular \"rulers\" and \"clocks\" licenses mitotic exit only after proper chromosome separation.

cell biology↗

bioRxiv2019

Immunization with recombinant enolase of Sporothrix spp (rSsEno) confers effective protection against sporotrichosis in mice

In recent years, research has focused on the immunoreactive components of the S. schenckii cell wall that can be relevant targets for preventive and therapeutic vaccines against sporotrichosis, an emergent worldwide mycosis. In previous studies, we identified a 47-kDa enolase as an immunodominant antigen in mice vaccinated with purified fungal wall proteins and adjuvants. In this study, the immunolocalization of this immunogen in the cell wall of S. schenckii and S. brasiliensis is shown for the first time. In addition, a recombinant enolase of Sporothrix spp (rSsEno) was studied with the adjuvant Montanide Pet-GelA (PGA) as a vaccine candidate. The rSsEno was produced with high purity. In addition, mice immunized with rSsEno plus PGA showed increased antibody titers against enolase and increased median survival time comparedto nonimmunized or rSsEno-immunized mice. Enolase immunization induced a predominant T-helper-1 (Th1) cytokine pattern in splenic cells after in vitro stimulation with rSsEno. Elevated production of interferon-{gamma} (IFN-{gamma}) and interleukin-2 (IL-2) was observed with other cytokines involved in the innate immune defense, such as TNF-alpha, IL-6, and IL-4, which are necessary for antibody production. These results suggest that we should continue testing this antigen as a potential vaccine candidate against sporotrichosis.

immunology↗

bioRxiv2017

Single-cell RNA-Sequencing uncovers transcriptional states and fate decisionsin haematopoiesis

The success of marker-based approaches for dissecting haematopoiesis in mouse and human is reliant on the presence of well-defined cell-surface markers specific for diverse progenitor populations. An inherent problem with this approach is that the presence of specific cell surface markers does not directly reflect the transcriptional state of a cell. Here we used a marker-free approach to computationally reconstruct the blood lineage tree in zebrafish and order cells along their differentiation trajectory, based on their global transcriptional differences. Within the population of transcriptionally similar stem and progenitor cells our analysis revealed considerable cell-to-cell differences in their probability to transition to another, committed state. Once fate decision was executed, the suppression of transcription of ribosomal genes and up-regulation of lineage specific factors coordinately controlled lineage differentiation. Evolutionary analysis further demonstrated that this haematopoietic program was highly conserved between zebrafish and higher vertebrates.

cell biology↗

bioRxiv2016

Loss of the homologous recombination gene rad51 leads to Fanconi anemia-like symptoms in zebrafish

RAD51 is an indispensable homologous recombination protein, necessary for strand invasion and crossing over. It has recently been designated as a Fanconi anemia (FA) gene, following the discovery of two patients carrying dominant negative mutations. FA is a hereditary DNA repair disorder characterized by various congenital abnormalities, progressive bone marrow failure and cancer predisposition. In this paper, we describe the first viable vertebrate model of RAD51 loss. Zebrafish rad51 loss-of-function mutants developed key features of FA, including hypocellular kidney marrow, sensitivity to crosslinking agents and decreased size. We show that some of these symptoms stem from both decreased proliferation and increased apoptosis of embryonic hematopoietic stem and progenitor cells. Co-mutation of p53 was able to rescue the hematopoietic defects seen in the single mutants, but led to tumor development. We further demonstrate that prolonged inflammatory stress can exacerbate the hematological impairment, leading to an additional decrease in kidney marrow cell numbers. These findings strengthen the assignment of RAD51 as a Fanconi gene and provide more evidence for the notion that aberrant p53 signaling during embryogenesis leads to the hematological defects seen later in life in FA. Further research on this novel zebrafish FA model will lead to a deeper understanding of the molecular basis of bone marrow failure in FA and the cellular role of RAD51.\n\nSignificance statementThe homologous recombination protein RAD51 has been extensively studied in prokaryotes and lower eukaryotes. However, there is a significant lack of knowledge of the role of this protein and its regulation in an in-vivo context in vertebrates. Here we report the first viable vertebrate mutant model of rad51 in zebrafish. These mutant fish enabled us to confirm for the first time the recently discovered role of RAD51 in Fanconi anemia pathogenesis. We report that p53 linked embryonic stem cell defects directly lead to hematological impairments later in life. Co-mutation of rad51 with p53 rescues the observed hematological defects, but predisposes the fish to early tumor development. The application of this model opens new possibilities to advance Fanconi anemia drug discovery.

genetics↗