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Sexual reproduction is widespread in eukaryotes; however, only asexual reproduction has been observed in unicellular red algae, including Galdieria, which branched early in Archaeplastida. Galdieria possesses a small genome; it is polyextremophile, grows either photoautotrophically, mixotrophically, or heterotrophically, and is being developed as an industrial source of vitamins and pigments because of its high biomass productivity. Here, we show that Galdieria exhibits a sexual life cycle, alternating between cell-walled diploid and cell wall-less haploid, and that both phases can proliferate asexually. The haploid can move over surfaces and undergo self-diploidization or generate heterozygous diploids through mating. Further, we prepared the whole genome and a comparative transcriptome dataset between the diploid and haploid and developed genetic tools for the stable gene expression, gene disruption, and selectable marker recycling system using the cell wall-less haploid. The BELL/KNOX and MADS-box transcription factors, which function in haploid-to-diploid transition and development in plants, are specifically expressed in the haploid and diploid, respectively, and are involved in the haploid-to-diploid transition in Galdieria, providing information on the missing link of the sexual life cycle evolution in Archaeplastida. Four actin genes are differently involved in motility of the haploid and cytokinesis in the diploid, both of which are myosin independent and likely reflect ancestral roles of actin. We have also generated photosynthesis-deficient mutants, such as blue-colored cells, which were depleted in chlorophyll and carotenoids, for industrial pigment production. These features of Galdieria facilitate the understanding of the evolution of algae and plants and the industrial use of microalgae.
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Actinas , Rodófitas , Actinas/genética , Animais , Carotenoides , Clorofila , Diploide , Genômica , Haploidia , Estágios do Ciclo de Vida , Plantas/genética , Rodófitas/genética , Fatores de Transcrição/genética , VitaminasRESUMO
BACKGROUND: Previous studies have shown shorter duration of general anesthesia in smokers but it is unclear in regional anesthesia among smokers. We investigated the association between smoking status and the duration of regional anesthesia. METHODS: A total of 77 patients with a mean age of 47.3 years who underwent lower extremity orthopaedic surgery under regional anesthesia between January 2021 and June 2022 were enrolled. Sixteen patients were smokers and 57 patients were non-smokers. Propensity score matching was performed to balance patient characteristics. Our primary outcome was the time to onset of motor or sensory blockade and the duration required for full recovery of motor or sensory function. RESULTS: The time to sensory loss was 43.4 (SD 35.9) minutes in the smoking group and 39.6 (SD 31.7) minutes in the non-smoking group (p = 0.69), and the time to motor blockade was 37.0 (SD 28.4) minutes in the smoking group and 30.1 (SD 24.1) minutes in the non-smoking group (p = 0.35). The time for recovery of sensory function was 1146.7 (SD 197.8) minutes in the smoking group and 1024.6 (SD 177.9) minutes in the non-smoking group (p = 0.024). The time to recovery of motor function was 978.3 (SD 220.5) minutes in the smoking group and 1090.9 (SD 222.8) minutes in the non-smoking group (p = 0.08). The duration of sensory effect was significantly longer in the smoking group than in the non-smoking group. CONCLUSIONS: We found no significant association in the onset of regional anesthesia, but the duration of sensory blockade was significantly longer in the smoking group than in the non-smoking group. Hence, attention should be paid to the risks of the insensate limb in smokers due to prolonged sensory blockade as compared to non-smokers, rather than be concerned about delays in the onset of anesthesia.
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While photoautotrophic organisms utilize inorganic nitrogen as the nitrogen source, heterotrophic organisms utilize organic nitrogen and thus do not generally have an inorganic nitrogen assimilation pathway. Here, we focused on the nitrogen metabolism of Rapaza viridis, a unicellular eukaryote exhibiting kleptoplasty. Although belonging to the lineage of essentially heterotrophic flagellates, R. viridis exploits the photosynthetic products of the kleptoplasts and was therefore suspected to potentially utilize inorganic nitrogen. From the transcriptome data of R. viridis, we identified gene RvNaRL, which had sequence similarity to genes encoding nitrate reductases in plants. Phylogenetic analysis revealed that RvNaRL was acquired by a horizontal gene transfer event. To verify the function of the protein product RvNaRL, we established RNAi-mediated knock-down and CRISPR-Cas9-mediated knock-out experiments for the first time in R. viridis and applied them to this gene. The RvNaRL knock-down and knock-out cells exhibited significant growth only when ammonium was supplied. However, in contrast to the wild-type cells, no substantial growth was observed when nitrate was supplied. Such arrested growth in the absence of ammonium was attributed to impaired amino acid synthesis due to the deficiency of nitrogen supply from the nitrate assimilation pathway; this in turn resulted in the accumulation of excess photosynthetic products in the form of cytosolic polysaccharide grains, as observed. These results indicate that RvNaRL is certainly involved in nitrate assimilation by R. viridis. Thus, we inferred that R. viridis achieved its advanced kleptoplasty for photoautotrophy, owing to the acquisition of nitrate assimilation via horizontal gene transfer.
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Compostos de Amônio , Nitratos , Nitrato Redutase/genética , Nitrato Redutase/metabolismo , Nitratos/metabolismo , Filogenia , Nitrogênio/metabolismoRESUMO
Skin lesions, cataracts, and congenital anomalies have been frequently associated with inherited deficiencies in enzymes that synthesize cholesterol. Lanosterol synthase (LSS) converts (S)-2,3-epoxysqualene to lanosterol in the cholesterol biosynthesis pathway. Biallelic mutations in LSS have been reported in families with congenital cataracts and, very recently, have been reported in cases of hypotrichosis. However, it remains to be clarified whether these phenotypes are caused by LSS enzymatic deficiencies in each tissue, and disruption of LSS enzymatic activity in vivo has not yet been validated. We identified two patients with novel biallelic LSS mutations who exhibited congenital hypotrichosis and midline anomalies but did not have cataracts. We showed that the blockade of the LSS enzyme reaction occurred in the patients by measuring the (S)-2,3-epoxysqualene/lanosterol ratio in the forehead sebum, which would be a good biomarker for the diagnosis of LSS deficiency. Epidermis-specific Lss knockout mice showed neonatal lethality due to dehydration, indicating that LSS could be involved in skin barrier integrity. Tamoxifen-induced knockout of Lss in the epidermis caused hypotrichosis in adult mice. Lens-specific Lss knockout mice had cataracts. These results confirmed that LSS deficiency causes hypotrichosis and cataracts due to loss-of-function mutations in LSS in each tissue. These mouse models will lead to the elucidation of the pathophysiological mechanisms associated with disrupted LSS and to the development of therapeutic treatments for LSS deficiency.
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Catarata/genética , Epiderme/patologia , Hipotricose/genética , Transferases Intramoleculares/genética , Cristalino/patologia , Adolescente , Animais , Catarata/congênito , Catarata/patologia , Colesterol/metabolismo , Análise Mutacional de DNA , Modelos Animais de Doenças , Epiderme/enzimologia , Saúde Holística , Humanos , Hipotricose/congênito , Hipotricose/patologia , Transferases Intramoleculares/metabolismo , Lanosterol/análise , Lanosterol/metabolismo , Cristalino/enzimologia , Masculino , Camundongos , Camundongos Knockout , Mutação , Linhagem , Sebo/química , Sequenciamento do ExomaRESUMO
[Purpose] This study aimed to evaluate the reliability and validity of measuring the range of motion of joints using a remote videoconferencing system (Zoom) and a smartphone application. [Participants and Methods] This study included 16 young and healthy adults. The participants were instructed to perform shoulder joint flexion exercises in a seated position, with automatic motions, and maintain that posture throughout the measurement. Two measurements were performed: 1) angle measurement using a three-dimensional (3D) motion analyzer, and 2) angle measurement using the videoconference software, Zoom, and a smartphone application. Intra- and inter-rater reliabilities were calculated using the intraclass correlation coefficients (ICC). The degree of agreement between the representative values of each measurer and the 3D motion analyzer was examined. [Results] ICC (1, 1) for intra-examiner reliability were 0.912 and 0.996. For the inter-rater reliability, the ICC (2, 1) was 0.945. The correlation coefficient between each examiner's value and the value of the 3D motion analyzer was 0.955 and 0.980, respectively. The Bland-Altman analysis results indicated no systematic error. [Conclusion] The method of remotely measuring joint range of motion using Zoom and a smartphone application demonstrated high reliability and validity.
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[Purpose] This study aimed to investigate the reliability and validity of the quantitative evaluation of anticipatory postural adjustments using smartphones. [Participants and Methods] The study included 10 young control participants who underwent a one-legged stance with an accelerometer and a smartphone that were simultaneously attached to their lower back (L5). Acceleration was measured as the mediolateral component of the lumbar movement toward the stance side. The peak value of the time (peak latency) and the amount of displacement (peak magnitude) in the stance side direction of the lumbar acceleration were analyzed as anticipatory postural adjustment features. Intra-rater reliability was calculated for both accelerometer and smartphone measurements, while inter-rater reliability was calculated for smartphone measurements by two examiners. Validity was determined for both accelerometer and smartphone measurements. [Results] In this study, the intra-rater reliability of the peak latency and peak magnitude in accelerometer and smartphone measurements was confirmed, as was the inter-rater reliability in smartphone measurements. The intra-rater reliability was confirmed through re-testing, while the validity of the accelerometer and smartphone measurements was also confirmed. [Conclusion] The findings of this study suggest that the use of smartphones to measure anticipatory postural adjustments is highly reliable and valid, making it a useful clinical balance index. The method is simple and can be used for continuous patient monitoring.
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Metabolism, cell cycle stages, and related transcriptomes in eukaryotic algae change with the diel cycle of light availability. In the unicellular red alga Cyanidioschyzon merolae, the S and M phases occur at night. To examine how diel transcriptomic changes in metabolic pathways are related to the cell cycle and to identify all genes for which mRNA levels change depending on the cell cycle, we examined diel transcriptomic changes in C. merolae In addition, we compared transcriptomic changes between the wild type and transgenic lines, in which the cell cycle was uncoupled from the diel cycle by the depletion of either cyclin-dependent kinase A or retinoblastoma-related protein. Of 4,775 nucleus-encoded genes, the mRNA levels of 1,979 genes exhibited diel transcriptomic changes in the wild type. Of these, the periodic expression patterns of 454 genes were abolished in the transgenic lines, suggesting that the expression of these genes is dependent on cell cycle progression. The periodic expression patterns of most metabolic genes, except those involved in starch degradation and de novo deoxyribonucleotide triphosphate synthesis, were not affected in the transgenic lines, indicating that the cell cycle and transcriptomic changes in most metabolic pathways are independent of the diel cycle. Approximately 40% of the cell-cycle-dependent genes were of unknown function, and approximately 19% of these genes of unknown function are shared with the green alga Chlamydomonas reinhardtii The data set presented in this study will facilitate further studies on the cell cycle and its relationship with metabolism in eukaryotic algae.
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Ciclo Celular/fisiologia , Rodófitas/metabolismo , Transcriptoma/genética , Metabolismo dos Carboidratos/genética , Metabolismo dos Carboidratos/fisiologia , Ciclo Celular/genética , Chlamydomonas reinhardtii/genética , Chlamydomonas reinhardtii/metabolismo , Rodófitas/genéticaRESUMO
Some microalgae are adapted to extremely acidic environments in which toxic metals are present at high levels. However, little is known about how acidophilic algae evolved from their respective neutrophilic ancestors by adapting to particular acidic environments. To gain insights into this issue, we determined the draft genome sequence of the acidophilic green alga Chlamydomonas eustigma and performed comparative genome and transcriptome analyses between Ceustigma and its neutrophilic relative Chlamydomonas reinhardtii The results revealed the following features in Ceustigma that probably contributed to the adaptation to an acidic environment. Genes encoding heat-shock proteins and plasma membrane H+-ATPase are highly expressed in Ceustigma This species has also lost fermentation pathways that acidify the cytosol and has acquired an energy shuttle and buffering system and arsenic detoxification genes through horizontal gene transfer. Moreover, the arsenic detoxification genes have been multiplied in the genome. These features have also been found in other acidophilic green and red algae, suggesting the existence of common mechanisms in the adaptation to acidic environments.
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Adaptação Fisiológica/genética , Chlamydomonas reinhardtii/genética , Genoma de Planta , Proteínas de Plantas/genética , Chlamydomonas reinhardtii/metabolismo , Concentração de Íons de Hidrogênio , Proteínas de Plantas/metabolismoRESUMO
Background: This study aimed to reveal differences in the effectiveness of rehabilitation in improving activities of daily living (ADL) in patients with acute stroke across age groups and propose age-appropriate rehabilitation strategies. Methods: This observational study analyzed nationwide administrative data of inpatients admitted to hospitals with acute stroke between April 1, 2018, and March 31, 2020. The data included the average length of daily rehabilitation sessions, weekly frequency of rehabilitation sessions, and initiation of rehabilitation within three days. The primary outcome was the improvement in the Barthel Index (BI) score from admission to discharge. We classified the patients based on age and analyzed improvements in ADL according to rehabilitation characteristics. Results: An increased daily rehabilitation dose was associated with improved ADL, except in patients aged <65 years (risk ratios and 95% confidence intervals [CIs] in the 65-74, 75-85, and ≥85 age groups: 1.20 [1.14â1.27], 1.21 [1.15â1.27], and 1.43 [1.34â1.53], respectively; all p <0.001 vs. <65 years: 1.05 [0.98-â1.12]; p=0.18). A rehabilitation frequency of seven sessions per week was associated with improved ADL in the 75-85-year and ≥85-year age groups (1.06 [1.02â1.10] and 1.08 [1.03â1.13], respectively; both p <0.001). The effects of initiating rehabilitation within three days on ADL post-admission did not differ across age groups. Conclusions: Increasing the daily dose of rehabilitation was significantly associated with improved ADL in all age groups while increasing the frequency of rehabilitation per week improved ADL in older and very old patients.
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PURPOSE: Rehabilitation after hip fracture surgery is crucial for improving physical function. Additional rehabilitation over the weekend or after working hours is reportedly associated with improved physical function; however, this may not apply to an aging population, including patients aged > 90 years. This study aimed to investigate the association between additional weekend rehabilitation and functional outcomes in different age groups. METHODS: This study analyzed a cohort of patients aged ≥ 60 years who had hip fractures and were operated on from 2010 to 2018. Data were extracted from a nationwide multicentre database. Functional outcomes at discharge were compared between patients who underwent rehabilitation on weekdays only and those who underwent rehabilitation on both weekdays and weekends. The patient groups were selected using propensity score matching analysis. Furthermore, a subgroup-analysis was conducted on patients in their 60 s, 70 s, 80 s, and 90 s. RESULTS: A total of 390,713 patients underwent surgery during the study period. After matching, each group comprised 129,583 pairs of patients. Patients who underwent weekend rehabilitation exhibited improved physical function in transferring, walking, and stair climbing at discharge, as compared with patients who did not (odds ratio [95% confidence interval]: 1.17 [1.15-1.19], 1.17 [1.15-1.2], and 1.06 [1.03-1.08], respectively). In subgroup analysis, except for stair climbing, the positive association between weekend rehabilitation and patient function was observed across all age groups. CONCLUSION: Weekend rehabilitation was significantly associated with improved physical function. Given the limited healthcare resources, high-demand activities such as stair climbing may be reserved for younger age groups to optimise rehabilitation therapy.
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OBJECTIVES: Using smartphones, we aimed to clarify the characteristics of anticipatory postural adjustments (APA) in older adults and examine the relationship between cognitive and balance functions. METHODS: The study participants were 10 young and 13 older adults. An accelerometer built into a smartphone was attached to the lower back (L5) of the participant, and acceleration in the mediolateral direction was measured using a one-leg stance (OLS). As APA features, we analyzed the time to the peak value in the stance direction (peak latency [PL]) and the amount of displacement to the peak value in the stance direction (peak magnitude [PM]). Additionally, the measured PL was divided by PM for each group to obtain the APA ratio (APAr). We investigated the relationship between the APAr and Mini-BESTest subitems. RESULTS: Older adults showed delayed PL and decreased PM levels (p < 0.01). While in the Mini-BESTest sub-items, deductions were most common in the order of dual-task and single-leg standing, and most participants with low APAr scores were degraded in APA of sub-items. The correlation was observed between APAr and both TUG and dual-task cost (DTC) (r= -0.56, r= -0.67). According to the receiver operating characteristic curve, the APAr value was 1.71 in the older age group. CONCLUSIONS: Older adults showed delayed PL and decreased PM, and APAr was associated with cognitive and locomotor functions. By evaluating the APAr at the initiation of movement, it may be possible to distinguish the APA of the older adluts from the possible to the impossible of OLS movement.
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Acelerometria , Cognição , Equilíbrio Postural , Smartphone , Humanos , Equilíbrio Postural/fisiologia , Idoso , Masculino , Feminino , Cognição/fisiologia , Acelerometria/instrumentação , Adulto Jovem , Adulto , Antecipação Psicológica/fisiologiaRESUMO
Aims: The aim of this study was to investigate the association between additional rehabilitation at the weekend, and in-hospital mortality and complications in patients with hip fracture who underwent surgery. Methods: A retrospective cohort study was conducted in Japan using a nationwide multicentre database from April 2010 to March 2018, including 572,181 patients who had received hip fracture surgery. Propensity score matching was performed to compare patients who received additional weekend rehabilitation at the weekend in addition to rehabilitation on weekdays after the surgery (plus-weekends group), as well as those who did not receive additional rehabilitation at the weekend but did receive weekday rehabilitation (weekdays-only group). After the propensity score matching of 259,168 cases, in-hospital mortality as the primary outcome and systemic and surgical complications as the secondary outcomes were compared between the two groups. Results: The plus-weekends group was significantly associated with lower in-hospital mortality rates compared with the weekdays-only group (hazard ratio 0.86; 95% confidence interval 0.8 to 0.92; p < 0.001). Systemic complications such as acute coronary syndrome, heart failure, renal failure, and sepsis were significantly lower in the plus-weekends group, whereas urinary tract infection (UTI) and surgical complications such as surgical site infection and haematoma were significantly higher in the plus-weekends group. Conclusion: Additional weekend rehabilitation was significantly associated with lower in-hospital mortality, as well as acute coronary syndrome, heart failure, renal failure, and sepsis, but was also significantly associated with a higher risk of UTI and surgical complications. This result can facilitate the effective use of the limited rehabilitation resources at the weekend and improve the clinical awareness of specific complications. To establish more robust causal associations between additional rehabilitation over the weekend and clinical outcomes, further prospective studies or randomized controlled trials with larger sample sizes are warranted.
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Síndrome Coronariana Aguda , Fraturas do Quadril , Insuficiência Renal , Humanos , Mortalidade Hospitalar , Estudos Retrospectivos , Estudos Prospectivos , Fraturas do Quadril/cirurgia , Admissão do PacienteRESUMO
OBJECTIVE: To investigate a smartphone-enabled quantitative evaluation of anticipatory postural adjustments (APA) during one-leg stance (OLS) movements among individuals with Parkinson's disease (PD). METHODS: This cross-sectional study included 10 young controls, 10 older individuals, and 13 individuals with PD. A smartphone and accelerometer were attached to the participants' lower back (L5), and the movements of the lower back toward the stance side during OLS were measured. For acceleration, the time to the peak value in the stance direction (peak latency [PL]) and the amount of displacement to the peak value in the stance direction (peak magnitude [PM]) were analyzed as APA characteristics. Additionally, the measured PL was divided by the PM for each group to obtain the APA ratio (APAr) as a new index. RESULTS: Individuals with PD showed a delayed PL and decreased PM (vs. young controls: p = .002 for PL, p < .001 for PM) (vs. older individuals: p = .022 for PL, p = .001 for PM). The APAr clustered the young controls, older individuals, and individuals with PD. According to the receiver operating characteristic curve the APAr value was 0.95, and individuals in the PD group were identified (i.e. area under the curve: 0.98; sensitivity: 85.0%; specificity: 100%). Moreover the APAr was correlated with severity and balance ability in individuals with PD (p = .015 for NFOG-Q, p = .028 for UPDRS, p = .036 for TUG, p = .015 for Mini-BESTest, p = .018 for OLS time). CONCLUSIONS: This smartphone-based evaluation using the APAr index was reflective of disease severity and decreased balance ability among individuals with PD. The facilitation of this measurement can help clinicians and physiotherapists quantitatively evaluate the APA of individuals with PD at laboratories and hospitals as well as in home environments.
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BACKGROUND AND OBJECTIVE: Accelerations, ground reaction force data, and other quantitative data obtained from kinematic analyses of gait initiation serve as measures of dyskinesia in patients with Parkinson's disease. The objective of this study was to determine whether a separate center of pressure information could reveal new characteristics of reduced anticipatory postural adjustments in patients with Parkinson's disease. METHODS: Ten healthy elderly subjects and 10 patients with Parkinson's disease participated in this study. Motions at gait initiation in response to a light signal to begin the task were analyzed. Anticipatory postural adjustments were characterized using trunk acceleration data and center of pressure displacement data. RESULTS: The separated center of pressure in patients with Parkinson's disease showed longer peak latency (p < .01) and larger peak magnitude (p < .01) in the stance leg than in the stepping leg. In patients with Parkinson's disease, the displacement peak latency of the stance leg center of pressure correlated negatively with the Timed Up and Go time (r = -0.46, p < .05), while displacement peak latency of the stepping leg center of pressure correlated negatively with Unified Parkinson's Disease Rating Scale (r= -0.47, p < .05), and positively with Berg Balance Scale score (r = 0.50, p < .05). CONCLUSIONS: Patients with Parkinson's disease experience asymmetry between the stance leg and stepping leg at gait initiation. These findings may help clinicians understand the changes to motor function in patients with Parkinson's disease and suggest strategies for improved rehabilitation training.
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Transtornos Neurológicos da Marcha , Doença de Parkinson , Humanos , Idoso , Equilíbrio Postural/fisiologia , Marcha/fisiologia , Fenômenos BiomecânicosRESUMO
Secondary loss of photosynthesis is observed across almost all plastid-bearing branches of the eukaryotic tree of life. However, genome-based insights into the transition from a phototroph into a secondary heterotroph have so far only been revealed for parasitic species. Free-living organisms can yield unique insights into the evolutionary consequence of the loss of photosynthesis, as the parasitic lifestyle requires specific adaptations to host environments. Here, we report on the diploid genome of the free-living diatom Nitzschia putrida (35 Mbp), a nonphotosynthetic osmotroph whose photosynthetic relatives contribute ca. 40% of net oceanic primary production. Comparative analyses with photosynthetic diatoms and heterotrophic algae with parasitic lifestyle revealed that a combination of gene loss, the accumulation of genes involved in organic carbon degradation, a unique secretome, and the rapid divergence of conserved gene families involved in cell wall and extracellular metabolism appear to have facilitated the lifestyle of a free-living secondary heterotroph.
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OBJECTIVES: To determine whether individual measurements of the centre of pressure for the stance and stepping legs can reveal new characteristics of reduced anticipatory postural adjustments during gait initiation in post-stroke hemiplegic patients. METHODS: Subjects included 30 stroke patients and 10 healthy age-matched controls. The acceleration of the trunk, and the centre of pressure of each leg, were measured during gait initiation, 3 times each with the paretic and non-paretic legs leading. Anticipatory postural adjustments were characterized using trunk acceleration and centre of pressure displacement data. RESULTS: Latency of the posterior displacement peak of the paretic leg centre of pressure with either the paretic or non-paretic leg leading was significantly longer in stroke patients compared with controls, and was also longer than that of the non-paretic leg. The magnitude of the posterior displacement peak of the paretic leg centre of pressure was smaller than that of the non-paretic leg. Peak latency of the paretic stepping leg centre of pressure correlated with the clinical measures of motor dysfunction, postural balance, and gait ability. CONCLUSION: Measurements of the latency and magnitude of centre of pressure displacement peak individually for the paretic and non-paretic legs can help elucidate the mechanism behind reduced anticipatory postural adjustments. This information will be useful in designing new treatment strategies for stroke patients.
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Transtornos Neurológicos da Marcha/fisiopatologia , Hemiplegia/fisiopatologia , Perna (Membro)/fisiopatologia , Acidente Vascular Cerebral/fisiopatologia , Idoso , Antecipação Psicológica , Fenômenos Biomecânicos , Feminino , Análise da Marcha , Humanos , Masculino , Equilíbrio Postural , PressãoRESUMO
Dinothrix paradoxa and Gymnodinium quadrilobatum are benthic dinoflagellates possessing diatom-derived tertiary plastids, so-called dinotoms. Due to the lack of available genetic information, their phylogenetic relationship remains unknown. In this study, sequencing of 18S ribosomal DNA (rDNA) and the rbcL gene from temporary cultures isolated from natural samples revealed that they are close relatives of another dinotom, Galeidinium rugatum. The morphologies of these three dinotoms differ significantly from each other; however, they share a distinctive life cycle, in which the non-motile cells without flagella are their dominant phase. Cell division occurs in this non-motile phase, while swimming cells only appear for several hours after being released from each daughter cell. Furthermore, we succeeded in isolating and establishing two novel dinotom strains, HG180 and HG204, which show a similar life cycle and are phylogenetically closely related to the aforementioned three species. The non-motile cells of strain HG180 are characterized by the possession of a hemispheroidal cell covered with numerous nodes, while those of the strain HG204 form aggregations consisting of spherical smooth-surface cells. Based on the similarity in life cycles and phylogenetic closeness, we conclude that all five species should belong to a single genus, Dinothrix, the oldest genus within this clade. We transferred Ga. rugatum and Gy. quadrilobatum to Dinothrix, and described strains HG180 and HG204 as Dinothrix phymatodea sp. nov. and Dinothrix pseudoparadoxa sp. nov.
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Endosymbiosis of unicellular eukaryotic algae into previously nonphotosynthetic eukaryotes has established chloroplasts in several eukaryotic lineages. In addition, certain unicellular organisms in several different lineages ingest algae and utilize them as temporal chloroplasts (kleptoplasts) for weeks to months before digesting them. Among these organisms, the dinoflagellate Nusuttodinium aeruginosum ingests the cryptomonad Chroomonas sp. and enlarges the kleptoplast with the aid of the cryptomonad nucleus. To understand how the cryptomonad nucleus is remodeled in the dinoflagellate, here we examined changes in the transcriptome and ploidy of the ingested nucleus. We show that, after ingestion, genes involved in metabolism, translation, and DNA replication are upregulated while those involved in sensory systems and cell motility are downregulated. In the dinoflagellate cell, the cryptomonad nucleus undergoes polyploidization that correlates with an increase in the mRNA levels of upregulated genes. In addition, the ingested nucleus almost loses transcriptional responses to light. Because polyploidization and loss of transcriptional regulation are also known to have occurred during the establishment of endosymbiotic organelles, these changes are probably a common trend in endosymbiotic evolution. Furthermore, we show that the kleptoplast and dinoflagellate are more susceptible to high light than the free-living cryptomonad but that the ingested nucleus reduces this damage.
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Criptófitas , Dinoflagellida , Cloroplastos , Criptófitas/genética , Dinoflagellida/genética , Ploidias , Simbiose , TranscriptomaRESUMO
Replication of the circular bacterial chromosome is initiated at a unique origin (oriC) in a DnaA-dependent manner in which replication proceeds bidirectionally from oriC to ter. The nucleotide compositions of most bacteria differ between the leading and lagging DNA strands. Thus, the chromosomal DNA sequence typically exhibits an asymmetric GC skew profile. Further, free-living bacteria without genomes encoding dnaA were unknown. Thus, a DnaA-oriC-dependent replication initiation mechanism may be essential for most bacteria. However, most cyanobacterial genomes exhibit irregular GC skew profiles. We previously found that the Synechococcus elongatus chromosome, which exhibits a regular GC skew profile, is replicated in a DnaA-oriC-dependent manner, whereas chromosomes of Synechocystis sp. PCC 6803 and Nostoc sp. PCC 7120, which exhibit an irregular GC skew profile, are replicated from multiple origins in a DnaA-independent manner. Here we investigate the variation in the mechanisms of cyanobacterial chromosome replication. We found that the genomes of certain free-living species do not encode dnaA and such species, including Cyanobacterium aponinum PCC 10605 and Geminocystis sp. NIES-3708, replicate their chromosomes from multiple origins. Synechococcus sp. PCC 7002, which is phylogenetically closely related to dnaA-lacking free-living species as well as to dnaA-encoding but DnaA-oriC-independent Synechocystis sp. PCC 6803, possesses dnaA. In Synechococcus sp. PCC 7002, dnaA was not essential and its chromosomes were replicated from a unique origin in a DnaA-oriC independent manner. Our results also suggest that loss of DnaA-oriC-dependency independently occurred multiple times during cyanobacterial evolution and raises a possibility that the loss of dnaA or loss of DnaA-oriC dependency correlated with an increase in ploidy level.
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The order Trypanosomatida has been well studied due to its pathogenicity and the unique biology of the mitochondrion. In Trypanosoma brucei, four DNA polymerases, namely PolIA, PolIB, PolIC, and PolID, related to bacterial DNA polymerase I (PolI), were shown to be localized in mitochondria experimentally. These mitochondrion-localized DNA polymerases are phylogenetically distinct from other family A DNA polymerases, such as bacterial PolI, DNA polymerase gamma (Polγ) in human and yeasts, "plant and protist organellar DNA polymerase (POP)" in diverse eukaryotes. However, the diversity of mitochondrion-localized DNA polymerases in Euglenozoa other than Trypanosomatida is poorly understood. In this study, we discovered putative mitochondrion-localized DNA polymerases in broad members of three major classes of Euglenozoa-Kinetoplastea, Diplonemea, and Euglenida-to explore the origin and evolution of trypanosomatid PolIA-D. We unveiled distinct inventories of mitochondrion-localized DNA polymerases in the three classes: (1) PolIA is ubiquitous across the three euglenozoan classes, (2) PolIB, C, and D are restricted in kinetoplastids, (3) new types of mitochondrion-localized DNA polymerases were identified in a prokinetoplastid and diplonemids, and (4) evolutionarily distinct types of POP were found in euglenids. We finally propose scenarios to explain the inventories of mitochondrion-localized DNA polymerases in Kinetoplastea, Diplonemea, and Euglenida.