Biology subjects

Machado, E.

Publications and source records attributed to Machado, E..

8 recordsLinked to original sources

bioRxiv2026

Force sharing between plantarflexor muscles in sheep during treadmill gait

Muscle force sharing during locomotion is influenced by the mechanical demands of movement and the contractile properties of synergistic muscles. In cats, plantarflexor muscles exhibit distinct functional specialization, with the slow-fibred soleus maintaining relatively constant force across conditions while faster muscles such as the plantaris and gastrocnemius increase force production with increasing locomotor demand. However, it remains unclear whether similar force-sharing patterns occur in larger animals with different musculoskeletal designs. Therefore, the purpose of this study was to examine force sharing between the superficial digital flexor (SDF) and medial gastrocnemius (MG) muscles during treadmill locomotion in sheep. Tendon buckle force transducers were surgically implanted on the SDF and MG tendons of seven sheep, and in vivo muscle forces were recorded during walking and trotting across different speeds and inclines. Both muscles increased force with increasing speed and incline; however, speed had a substantially greater effect than incline. The SDF consistently produced greater absolute force than the MG across all conditions, whereas the MG exhibited slightly larger relative increases in force with increasing speed. Time to peak force decreased with increasing speed in both muscles, although the SDF reached peak force later in stance than the MG across conditions. In contrast to the distinct specialization observed in cats, neither muscle displayed a relatively condition-independent, soleus-like force contribution. These findings suggest that force sharing in sheep is more distributed across synergistic muscles and may reflect the influence of musculoskeletal design, tendon compliance, and mixed fibre-type composition on muscle function in larger species.

bioengineering↗

bioRxiv2024

Flanker task parameters are related to the strength of association between the ERN and anxiety: a meta-analysis

The error-related negativity (ERN)--an index of error monitoring--is associated with anxiety symptomatology. Although recent work suggests associations between the ERN and anxiety are relatively modest, little attention has been paid to how variation in task parameters may influence the strength of ERN-anxiety associations. To close this gap, the current meta-analysis assesses the possible influence of task parameter variation in the Flanker task--the most commonly used task to elicit the ERN--on observed ERN-anxiety associations. Here, we leveraged an existing open database of published/unpublished ERN-anxiety effect sizes, supplementing this database by further coding for variation in stimulus type (letter vs. arrow), response type (one-handed vs. two-handed), and block-level feedback (with vs. without). We then performed meta-regression analyses to assess whether variation in these Flanker task parameters moderated the effect size of ERN-anxiety associations. No evidence for an effect of stimulus type was identified. However, both response type and block-level feedback significantly moderated the magnitude of ERN-anxiety associations. Specifically, studies employing either a two-handed (vs. one-handed) task, or those with (vs. without) block-level feedback exhibited more than a two-fold increase in the estimated ERN-anxiety effect size. Thus, accounting for common variation in task parameters may at least partially explain apparent inconsistencies in the literature regarding the magnitude of ERN-anxiety associations. At a practical level, these data can inform the design of studies seeking to maximize ERN-anxiety associations. At a theoretical level, the results also inform testable hypotheses regarding the exact nature of the association between the ERN and anxiety.

neuroscience↗

bioRxiv2024

Phylogenomic and genomic analysis reveals unique and shared genetic signatures of Mycobacterium kansasii complex species

Species belonging to the Mycobacterium kansasii complex (MKC) are frequently isolated from humans and the environment and can cause serious diseases. The most common MKC infections are caused by the species M. kansasii (stricto sensu), leading to tuberculosis-like disease. However, a broad spectrum of virulence, antimicrobial resistance and pathogenicity of these non-tuberculous mycobacteria (NTM) are observed across the MKC. Many genomic aspects of the MKC that relate to these broad phenotypes are not well elucidated. Here, we performed genomic analyses from a collection of 665 MKC strains, isolated from environmental, animal and human sources. We inferred the MKC pangenome, mobilome, resistome, virulome and defense systems and show that the MKC species harbors unique and shared genomic signatures. High frequency of presence of prophages and different types of defense systems was observed. We found that the M. kansasii species splits into four lineages, of which three are lowly represented and mainly in Brazil, while one lineage is dominant and globally spread. Moreover, we show that four sub-lineages of this most distributed M. kansasii lineage emerged during the 20th century. Further analysis of the M. kansasii genomes revealed almost 300 regions of difference contributing to genomic diversity, as well as fixed mutations that may explain the M. kansasiis increased virulence and drug resistance. RepositoriesBioProject PRJNA1048499. Impact statementMycobacterium kansasii complex (MKC) is a group of closely related non-tuberculous mycobacteria species, recognized as a significant source of human infection. Species belonging to the MKC may present a broad spectrum of virulence, antimicrobial resistance and pathogenicity and there is a lack of knowledge about their genomic content related to these broad phenotypes. We have provided whole genomic sequencing DNA for 342 MKC isolates and, together with public data, investigated the MKC pangenome, mobilome, resistome, virulome and defense systems and show unique and shared genetic signatures within MKC species. Furthermore, with phylogenomic and bayesian population analysis, we inferred the distribution and emergence of the Mycobacterium kansasii species lineages and sub-lineages. This study has considerably expanded the MKC available data, by providing genomic sequences of isolates from countries and global regions with unknown or poorly MKC data until now. Data summaryNGS data generated in the study are available in the NCBI Sequence Read Archive (SRA) repository under the accession number PRJNA1048499 and the accession numbers for all data sets used are provided in Supplementary Table 1.

evolutionary biology↗

bioRxiv2022

Metabolic profiling of drought tolerance: revealing how citrus rootstocks modulate plant metabolism under varying water availability

Water stress is a major environmental factor affecting Citrus spp. and Rangpur lime is a drought-tolerant rootstock used to enhance orange yield in rainfed orchards. Here, we combined morpho-physiological analyses with metabolic profiling of roots and leaves of Valencia orange scions grafted onto Rangpur lime, Swingle citrumelo or Sunki mandarin rootstocks under water deficit. Our aim was to present a comprehensive spatio-temporal evaluation of citrus responses to drought and highlight the metabolic adjustments associated with drought tolerance induced by Rangpur lime. Plant responses were evaluated during the initial phase of reduction in water availability, when water deficit was maximum and also after rehydration. Fifty-eight primary metabolites were modulated by water deficit, mainly amino acids, organic acids and sugars. Metabolic changes indicated adjustments related to osmotic, energetic and redox processes under low water availability, which were dependent on rootstock and varied between roots and leaves and along the experimental period. Rangpur lime prioritized root growth in the initial phase of water deficit, which was linked to less sugar accumulation, changes in nucleotide metabolism, downregulation in Shikimic acid pathway and accumulation of arginine. After rehydration, the resume of shoot growth was associated with high accumulation of arginine and asparagine. The better performance of Rangpur lime seems to be associated with its high sensitivity of roots to changes in water availability and possible signaling compounds have been suggested.

plant biology↗

bioRxiv2020

ZeBraInspector, a whole organism screening platform enabling volumetric analysis of zebrafish brain white matter

In recent years, the zebrafish has become a well-established laboratory model. We describe here the ZeBraInspector (ZBI) platform for high-content 3D imaging (HCI) of 5 dpf zebrafish eleuthero-embryos (EEs). This platform includes a mounting method based on 3D-printed stamps to create a grid of wells in an agarose cast, facilitating batch acquisitions with a fast-confocal laser scanning microscope. We describe reference labeling in cleared fish with a fluorescent lipophilic dye. Based on this labeling, the ZBI software registers EE 3D images, making it possible to visualize numerous identically oriented EEs on a single screen, and to compare their morphologies and any fluorescent patterns at a glance. High-resolution 2D snapshots can be extracted. ZBI software is therefore useful for diverse high-content analyses (HCAs). Following automated segmentation of the lipophilic dye signal, the ZBI software performs volumetric analyses on whole EEs and their nervous system white matter. Through two examples, we illustrate the power of these analyses for obtaining statistically significant results from a small number of samples: the characterization of a phenotype associated with a neurodevelopmental mutation, and of the defects caused by treatments with a toxic anti-cancer compound.

neuroscience↗

bioRxiv2020

A semi-automated method for measuring xylem vessel length distribution

Knowledge about the length of xylem vessels is essential to understand water transport in plants because these multicellular units show a 100-fold variation, from less than a centimeter to many meters. However, the available methods to estimate vessel length distribution (VLD) are excessively time consuming and do not allow large and in-depth surveys. Here, we describe a semi-automated method to measure VLD using an automated Pneumatron device. Gas conductivity of a xylem tissue with a certain length is estimated in a straightforward and precise way with the Pneumatron in a way theoretically similar to the air-injection method. The method presented enables fast and easy measurements using multiple devices simultaneously (>50 samples day-1), which is a significant advantage. Here, the apparatus is described in detail as well as how measurements are taken. We also present the software and an R-script for data analysis. The method described represents an important contribution to studies on plant hydraulic architecture and can improve our understanding about the role of VLD in plant performance under varying water availability.

plant biology↗

bioRxiv2019

Significant temporal shifts on clonal and plasmid backgrounds of Enterobacteriaceae producing acquired AmpC in Portuguese clinical settings

OBJECTIVESTo provide detailed molecular data on clinical acquired AmpC (qAmpC)-producing Enterobacteriaceae from two different periods (2002-2008 and 2010-2013) in order to clarify the contribution of clonal and plasmid genetic platforms for the current epidemiological scenario concerning extended-spectrum beta-lactams resistance. METHODSWe analysed 1246 Enterobacteriaceae non-susceptible to third-generation cephalosporins from 2 hospitals and 1 community laboratory between 2010 and 2013. Bacterial identification, antibiotic susceptibility, identification of qAmpC and plasmid-mediated quinolone resistance genes, clonal (PFGE, MLST) and plasmid (S1-/I-CeuI-PFGE, replicon typing, hybridization) analysis were performed by standard methods. WGS was performed in two ST11-K. pneumoniae isolates harbouring DHA-1. RESULTSThe occurrence of qAmpC was lower (2.6%) than that observed in a previous survey (7.4%), and varied slightly over time. Isolates produced DHA-1 (53%), CMY-2 (44%) or DHA-6 (3%), but significant epidemiological changes were observed in the two surveys. While DHA-1 persisted in different institutions by selection of a worldwide epidemic IncR plasmid in a ST11 harbouring KL105, CMY-2 rates increased over time linked to IncI1 plasmids (instead of IncK or IncA/C2) in multiple E. coli clones. CONCLUSIONSThe higher frequency of DHA-1 qAmpC in these species contrasts with the scenario of most European countries. Furthermore, the different genetic backgrounds associated with either ESBL or qAmpC in our country might have contributed to their differential expansion.

epidemiology↗

bioRxiv2018

Stressed mothers, tolerant daughters: a case study about the physiological responses and growth of sugarcane plants under water deficit

Drought stress can imprint marks in plants after a previous exposure, leading to a permissive state that facilitates a more effective response to subsequent stress events. Such stress imprints would benefit plants obtained from progenitors previously exposed to drought. Herein, our hypothesis was that daughter plants obtained from mother plants previously exposed to water deficit will perform better under water deficit as compared to those obtained from mothers that did not face stressful conditions. Sugarcane mother plants were grown under well-hydrated conditions or subjected to three cycles of water deficit by water withholding. Then, daughter plants produced through vegetative propagation were subjected to water deficit. Leaf gas exchange was reduced under water deficit and daughters from mothers that experienced water deficit presented a faster recovery of CO2 assimilation and higher instantaneous carboxylation efficiency after rehydration as compared to daughters from mothers that did not face water deficit. Plants obtained from mother plants that faced water deficit showed the highest leaf proline concentration under water deficit as well as higher leaf H2O 2 concentration and leaf ascorbate peroxidase activity regardless of water regime. Under well-watered conditions, daughters from mothers that faced stressful conditions presented higher root H2O2 concentration and root catalase activity than ones from mothers that did not experience water shortage. Such physiological changes were associated with improvements in leaf area and shoot and root dry matter accumulation in daughters from stressed mothers. Our results suggest that root H2O2 concentration is a chemical signal associated with stress memory and improved sugarcane growth. Such findings bring a new perspective to sugarcane production systems, in which stress memory can be explored for improving drought tolerance in rainfed areas.

plant biology↗