Biology subjects

Avila, M.

Publications and source records attributed to Avila, M..

5 recordsLinked to original sources

bioRxiv2025

Seeking rhythmic patterns in microglial cells within the circadian pineal gland from male rats

Microglia, the innate immune cells of the brain, constitute a highly dynamic cell population that displays several functions influenced by the light:dark (L:D) cycle. Within the pineal gland (PG), a key organ of the circadian timing system, microglia actively participate in its development and homeostasis. However, little is known about their rhythmic features in this circadian organ. This study aimed to elucidate morphological and functional phenotypes of pineal microglial cells at two time points of the L:D cycle. We performed immunofluorescence staining and confocal microscopy on paraffin-embedded pineal sections from 3- and 18-month-old Wistar rats, analyzing samples collected at midday (ZT6) and midnight (ZT18). Our results showed that the density and spatial distribution of IBA1+ microglial cells did not vary between ZT6 and ZT18 in the 3-month-old PG. However, these cells exhibited reduced size and amoeboid-like shapes, along with a reduction in the expression of the phagocytosis inhibitor SIRP alpha, at ZT18 compared to ZT6. Moreover, IBA1+ cells were immunoreactive for the lysosomal marker CD68 and the autophagic marker LC3B at both ZTs. Additionally, contacts with PAX6+ cells were detected in the two ZTs analyzed. Interestingly, IBA1+ cells showed attenuated or abolished rhythmicity in morphological parameters and SIRP alpha expression levels in the 18-month-old PG. Our findings suggest that microglia undergo transitions into alerted states at night, characterized by small, rounded shapes and enhanced phagocytic capacity. This adaptation likely prepares them to respond to potential invading agents and other insults in the PG, which could impact the nocturnal melatonin production. Key pointsO_LIMicroglia within the rat pineal gland exhibit daily morphological and functional adaptations, enhancing their effectivity to respond against potential challenges in a time-dependent manner. C_LIO_LIOscillatory features of pineal microglia diminish with aging, suggesting an attenuation of their functions. C_LIO_LINocturnal reactivity of microglia within the pineal organ may influence its physiology, potentially affecting melatonin synthesis. C_LI

neuroscience↗

bioRxiv2024

Resource-efficiency of cyanobacterium production on Mars: Assessment and paths forward

Space agencies and private companies strive for a permanent human presence on the Moon and ultimately on Mars. Bioprocesses have been advocated as key enablers due to their ability to transform locally available resources into added-value materials. However, the resource-efficiency and scaling of space biosystems remain poorly understood, hindering quantitative estimates of their potential performance. We leveraged extensive cultivation experiments, where a cyanobacterium (Anabaena sp. PCC 7938) was subject to conditions attainable on Mars, to develop a model that can estimate bioprocess productivity and resource-efficiency as a function of water, light, temperature, regolith minerals and perchlorates, and atmospheric carbon and nitrogen. We show that a breakeven can be reached within a few years. We discuss research lines to improve both resource efficiency and the accuracy of the model, thereby reducing the need for costly tests in space and eventually leading to a biotechnology-supported, sustained human presence on Mars. TEASERBioprocess modeling shows that cyanobacterium-based biotechnologies can be a sustainable basis for resource production on Mars.

microbiology↗

bioRxiv2020

Population Genomics of Plasmodium vivax in Panama to Assess the Risk of Case Importation on Malaria Elimination

Malaria incidence in Panama has plateaued in recent years in spite of elimination efforts, with almost all cases caused by Plasmodium vivax. Notwithstanding, overall malaria prevalence remains low (fewer than 1 case per 1000 persons). We used selective whole genome amplification to sequence 96 P. vivax samples from Panama collected between 2007 and 2019 to study the population structure and transmission dynamics of the parasite. Imported cases resulting from increased levels of human migration could threaten malaria elimination prospects, and four of the samples evaluated came from individuals with travel history. We explored patterns of recent common ancestry among the samples and observed that a single highly genetically related lineage was dominant among the samples (47 out of 59 samples with good sequencing coverage), spanning the entire period of the collection (2007-2019) and all regions of the country. We also found a second, smaller clonal lineage of four parasites collected between 2017 and 2019. To explore the regional context of Panamanian P. vivax we conducted principal components analysis and constructed a neighbor-joining tree using these samples and samples collected worldwide from a previous study. Three of the four samples with travel history clustered with samples collected from their suspected country of origin (consistent with importation), while one appears to have been a result of local transmission. The small number of genetically unique Panamanian P. vivax samples clustered with samples collected from Colombia, suggesting they represent the genetically similar ancestral P. vivax population in Panama or were recently imported from Colombia. The low diversity we observe in Panama indicates that this parasite population has been previously subject to a severe bottleneck and may be eligible for elimination. Additionally, while we confirmed that P. vivax is imported to Panama from diverse geographic locations, the lack of impact from imported cases on the overall parasite population genomic profile suggests that onward transmission from such cases is limited and that imported cases may not presently pose a major barrier to elimination. Author SummaryPanama has greatly reduced P. vivax incidence, however, this progress has plateaued. Understanding parasite transmission patterns and identifying imported cases is critical to help Panama and other countries succeed in their elimination efforts. Genomic epidemiology and population genomics can help provide information needed to inform malaria control policy. In this study, we collected 100 Panamanian P. vivax samples from two collection periods (2007-2009 and 2017-2019), of which 59 yielded usable sequencing data. 4 samples had patient travel history data associated with them. We found that the majority of samples belong to a single highly related lineage, termed CL1. This lineage has persisted since at least 2007. We also highlight how genomic epidemiology can be used to spotlight parasites that may be imported as a result of human migration, as well as corroborate or refute the country of origin as suggested by patient travel history. We observe no evidence of outcrossing between these potentially imported parasites and the local Panamanian parasite population, suggesting that imported parasites are not driving ongoing malaria transmission in Panama. The low diversity we observe in Panama indicates that this parasite population has been previously subject to a severe bottleneck and may be eligible for elimination.

microbiology↗

bioRxiv2020

Self-renewal capacity of double negative 3 (DN3) early thymocytes preserves thymus autonomous function but compromises the β-selection checkpoint

T lymphocyte differentiation in the thymus relies on high cellular turnover, and cell competition enforces thymocyte replenishment. If deprived of competent progenitors, the thymus can maintain thymopoiesis autonomously for several weeks but this bears a high risk of leukemia. Here we show that double negative 3 early (DN3e) thymocytes can acquire stem cell like properties, which enables them to maintain thymopoiesis. Specifically, DN3e proved to be long-lived, they proliferated and differentiated in vivo, were necessary for autonomous thymopoiesis, and included DNA-label-retaining cells. Single cell RNAseq revealed a transcriptional program of thymopoiesis similar in autonomy and the controls. Nevertheless, a new population was identified in thymus autonomy that was enriched for an aberrant Notch target gene signature and bypassed the {beta}-selection checkpoint. In sum, DN3e have the potential to self-renew and differentiate in vivo if cell competition is compromised but this enables the accumulation of atypical cells, probably leading to leukemia.

immunology↗

bioRxiv2019

Better ears with eyes open: effects of multisensory stimulation with nonconscious visual stimuli on auditory learning

Audiovisual integration may improve unisensory perceptual performance and learning. Interestingly, this integration may occur even when one of the sensory modalities is not conscious to the subject, e.g., semantic auditory information may impact nonconscious visual perception. Studies have shown that the flow of nonconscious visual information is mostly restricted to early cortical processing, without reaching higher-order areas such as the parieto-frontal network. Thus, because multisensory cortical interactions may already occur in early stages of processing, we hypothesized that nonconscious visual stimulation might facilitate auditory pitch learning. In this study we used a pitch learning paradigm, in which individuals had to identify six pitches in a scale with constant intervals of 50 cents. Subjects were assigned to one of three training groups: the test group (Auditory + congruent unconscious visual, AV), and two control groups (Auditory only, A, and Auditory + incongruent unconscious visual, AVi). Auditory-only tests were done before and after training in all groups. Electroencephalography (EEG) was recorded throughout the experiment. Results show that the test group (AV, with congruent nonconscious visual stimuli) performed better during the training, and showed a greater improvement from pre-to post-test. Control groups did not differ from one another. Changes in the AV group were mainly due to performances in the first and last pitches of the scale. We also observed consistent EEG patterns associated with this performance improvement in the AV group, especially maintenance of higher theta-band power after training in central and temporal areas, and stronger theta-band synchrony between visual and auditory cortices. Therefore, we show that nonconscious multisensory interactions are powerful enough to boost auditory perceptual learning, and that increased functional connectivity between early visual and auditory cortices after training might play a role in this effect. Moreover, we provide a methodological contribution for future studies on auditory perceptual learning, particularly those applied to relative and absolute pitch training.

neuroscience↗