Precerebellar structures, mainly studied in weakly electric fish, act to remove the effects of the fish’s own movements on the electrical signals they receive, but do not directly control movement, nor do they have a clear error signal. The cerebellum does directly control movement – arguably the most prominent difference in function between the two structures. The most pronounced anatomical difference between precerebellar structures and the cerebellum itself is that the latter possesses an inferior olive. This conjunction suggests that the inferior olive carries out a function that is necessary for the control of movements. What is the crucial function that the inferior olive carries out? Summary A clue comes from the the example of the vestibulo-ocular reflex. Allowing image movement degrades the visual signal irretrievably. It is therefore necessary to issue movement commands to prevent image movement, as in the vestibular-ocular reflex. But then the output of the precerebellar system is no longer an estimate of the actual sensory signal and can no longer serve as an error signal. This problem appears to have been addressed by the evolution of the inferior olive, which does provide an error signal. The inferior olive thus allows the cerebellum to participate in the control of movements. We consider evidence about how this works in practice. The evidence supports the view that the computational function of the inferior olive is indeed to provide an error signal for the control of movement.
Introduction In quadrupeds, the motor repertoire of the forelimbs is typically more diverse than that of the hindlimbs due to more pronounced supraspinal control. This greater supraspinal control may manifest as lesser automaticity in forelimb movements during a relatively simple motor task, such as locomotion. The degree of automaticity can be estimated by the variability of certain movement parameters. However, such variability is rarely assessed separately for the forelimbs and hindlimbs. Sauropods appear to be the only group of animals for which, based on available data, it is possible to estimate the variability of stepping parameters for both the forelimbs and hindlimbs. Methods The forelimb and hindlimb stride length and step width were measured using outline drawings of 27 relatively long sauropod trackways. Their coefficients of variation were then calculated. Results An analysis of trackways revealed significant differences in the variability of step width and stride length between the forelimbs and hindlimbs for some trackways. In some cases, the stepping parameters of the hindlimbs were more variable. Significant negative correlations were found between estimated walking speed and (i) the coefficient of variation of forelimb stride length and (ii) the coefficient of variation of hindlimb step width. Conclusions These findings are consistent with a greater contribution of hindlimb-related mechanisms to locomotor organization in sauropods compared with several extant quadrupedal taxa.
Social stress is a fundamental environmental factor driving the pathophysiology of neuropsychiatric disorders. Chronic social defeat stress (CSDS) and vicarious defeat stress (VDS) are two widely used social stress paradigms, with VDS initially proposed as an alternative to CSDS. The present study integrated behavioral phenotypes, hippocampal proteomics, synaptic morphology, energy metabolism, neurotransmitter and tryptophan-kynurenine (TRP-KYN) metabolism, and inflammatory indicators to directly compare responses in adult male mice subjected to CSDS and VDS. Both CSDS and VDS mice showed significant social avoidance, reduced open-arm exploration in the elevated plus maze, prolonged feeding latency in the novelty-suppressed feeding test, and increased immobility in the tail suspension test. Meanwhile, reduced center-zone activity in the open field test, fewer transitions and shorter light-compartment time in the light/dark box test, and lower sucrose preference were observed only in CSDS mice. These findings indicate that CSDS produced more extensive and severe behavioral abnormalities. Hippocampal label-free quantitative proteomics identified 38 and 32 differentially expressed proteins in CSDS and VDS mice, respectively, with 11 shared between the two paradigms. Both paradigms caused ATP depletion, increased pro-inflammatory factors, elevated α-synuclein (α-Syn), and decreased postsynaptic density protein 95 (PSD95), with CSDS showing more severe changes. CSDS also upregulated inducible nitric oxide synthase (iNOS) while suppressing transforming growth factor-β (TGF-β) and interleukin-10 (IL-10), whereas VDS increased IL-10 without significantly affecting iNOS or TGF-β. In TRP-KYN metabolism, CSDS increased 3-hydroxykynurenine (3-HK) and quinolinic acid (QA) while decreasing kynurenic acid (KA), whereas VDS did not significantly affect these downstream metabolites. Regarding neurotransmitters, CSDS reduced dopamine (DA), serotonin (5-HT), norepinephrine (NE) and glutamate (Glu), while VDS decreased NE and DA and γ-aminobutyric acid (GABA). Additionally, lactate was significantly increased in VDS mice, whereas CSDS mice showed a non-significant numerical decrease in hippocampal lactate. Collectively, VDS is a distinct stressor rather than a simple substitute for CSDS and has a milder overall impact than CSDS. This study provides guidance for selecting stress models that better align with specific biological questions in preclinical research on anxiety and depression disorders.
The genus Abutilon Mill. (Malvaceae) comprises approximately 178 species distributed across tropical and subtropical regions, many of which hold significant ornamental, economic, and medicinal value; yet its taxonomic classification remains challenging. In this study, six species were sequenced from herbarium specimens, and the chloroplast (cp.) genomes of ten additional species were assembled de novo from publicly available raw data. Three previously reported cp. genomes were also incorporated to characterise cp. genome structure, identify polymorphic loci, and perform phylogenetic analyses. The cp. genomes ranged from 159,458 to 160,454 bp and exhibited the typical quadripartite structure, with each genome containing 112 unique genes (78 protein-coding, 30 tRNA, and 4 rRNA) that showed conserved content and organisation. These genomes exhibited high similarity in GC content, inverted repeat boundaries, relative synonymous codon usage, amino acid frequencies, and substitution patterns. However, notable variation was observed in the total number of simple sequence repeats, ranging from 70 to 97 per genome. Selection analyses indicated predominant purifying selection, with evidence of episodic positive selection detected in rpoC2, rbcL, and ycf1. Two codons in rbcL were clade-specific and provided phylogenetic signal distinguishing Australian and Old World pantropical species. Nucleotide diversity analysis identified six highly polymorphic intergenic spacers (trnH-psbA, rps19-rpl2, psbT-pbf1, psaC-ndhD, trnR-atpA, and ndhJ-ndhK) that may be suitable for taxonomic studies. The phylogeny from maximum likelihood (ML) and Bayesian inference (BI) resolved two major clades: one comprising an exclusively Australian lineage occurring predominantly in arid and semi-arid environments, and the other a pantropical lineage spanning multiple continents. Abutilon grandifolium was recovered as sister to the remaining sampled Abutilon taxa in both ML and BI analyses, although no biogeographic origin inference can be drawn from this placement pending broader taxon sampling and integration of nuclear genomic data. These findings provide insights into the evolutionary dynamics of the cp. genome in Abutilon and offer a foundational genomic framework for refining Abutilon taxonomy.
Abstract Background Soil salinization poses a significant threat to agricultural production, necessitating innovative agronomic strategies to mitigate its impact. Salinity stress is a critical abiotic factor that hampers tomato growth by causing ionic imbalances, oxidative damage, and disruptions in physiological systems. This study investigated the effect of sodium silicate (Na₂SiO₃) in reducing salt stress in tomato plants exposed to 75 and 150 mM NaCl. Results The results indicated that salinity substantially decreased plant growth, the content of photosynthetic pigments, and the uptake of essential mineral nutrients. Concurrently, it heightened oxidative stress markers such as malondialdehyde (MDA), electrolyte leakage, hydrogen peroxide (H₂O₂), and hydroxyl radicals (•OH). Treatment with Na₂SiO₃, particularly at a concentration of 2 mM, significantly improved growth performance and photosynthetic pigment content. Silicon treatments enhanced the antioxidant defense mechanisms by increasing the activity of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR), and peroxidase (POX). Additionally, levels of ascorbate (AsA) and glutathione (GSH) were raised, leading to reduced oxidative damage and stabilized cellular membranes. The application of silicon also improved ionic homeostasis by decreasing sodium ion (Na⁺) concentration while enhancing the absorption of nitrogen (N), phosphorus (P), potassium (K⁺), and silicon. Conclusions In conclusion, the study demonstrated that silicon effectively alleviates salt stress in tomato plants by improving redox balance, enhancing antioxidant capacity, and regulating ion transport. The most effective concentration of Na₂SiO₃ was found to be 2 mM. The exogenous application of sodium silicate, especially at this concentration, helps to mitigate salinity-induced impairments in tomato plants by enhancing physiological performance, antioxidant defense, and ionic balance. This suggests its potential use as a sustainable agricultural strategy under salt-affected conditions.
