scholarly journals Bacterial communities in larger islands have reduced temporal turnover

2021 ◽  
Author(s):  
Damian W. Rivett ◽  
Shorok B. Mombrikotb ◽  
Hyun S. Gweon ◽  
Thomas Bell ◽  
Christopher van der Gast
Keyword(s):  
Bacterial Communities ◽  
Low Frequency ◽  
European Beech ◽  
Dispersal Limitation ◽  
Turnover Rates ◽  
Island Size ◽  
Species Area ◽  
Temporal Turnover ◽  
Underlying Mechanisms ◽  
Patterns And Processes

AbstractPatterns of species diversity provide fundamental insights into the underlying mechanisms and processes that regulate biodiversity. The species–time relationship (STR) has the potential to be one such pattern; in a comparable manner to its more extensively studied spatial analogue, the species–area relationship (SAR), which has been pivotal in the development of ecological models and theories. We sought to determine the mechanisms and processes that underpin STR patterns of temporal turnover by sampling bacterial communities within ten water-filled tree-holes on the same European beech tree through the course of a year. We took this natural model system to represent an archipelago of islands of varying sizes and with shared common immigration sources. We observed an inverse relationship between STR-derived turnover rates and island size. Further, turnover was related to island size and not island isolation within the study system as indicated by a low frequency of dispersal limitation and high homogenizing dispersal. Compared to SARs, STRs are understudied, as such, the findings from the current study should provide a renewed interest in STR-based patterns and processes.

scholarly journals Changes in electromyographic activity, mechanical power, and relaxation rates following inspiratory ribcage muscle fatigue

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Antonio Sarmento ◽  
Guilherme Fregonezi ◽  
Maria Lira ◽  
Layana Marques ◽  
Francesca Pennati ◽  
...  
Keyword(s):  
Muscle Fatigue ◽  
Low Frequency ◽  
Mechanical Power ◽  
Electromyographic Activity ◽  
Median Frequency ◽  
Relaxation Rates ◽  
Shortening Velocity ◽  
Inspiratory Muscles ◽  
Underlying Mechanisms

AbstractMuscle fatigue is a complex phenomenon enclosing various mechanisms. Despite technological advances, these mechanisms are still not fully understood in vivo. Here, simultaneous measurements of pressure, volume, and ribcage inspiratory muscle activity were performed non-invasively during fatigue (inspiratory threshold valve set at 70% of maximal inspiratory pressure) and recovery to verify if inspiratory ribcage muscle fatigue (1) leads to slowing of contraction and relaxation properties of ribcage muscles and (2) alters median frequency and high-to-low frequency ratio (H/L). During the fatigue protocol, sternocleidomastoid showed the fastest decrease in median frequency and slowest decrease in H/L. Fatigue was also characterized by a reduction in the relative power of the high-frequency and increase of the low-frequency. During recovery, changes in mechanical power were due to changes in shortening velocity with long-lasting reduction in pressure generation, and slowing of relaxation [i.e., tau (τ), half-relaxation time (½RT), and maximum relaxation rate (MRR)] was observed with no significant changes in contractile properties. Recovery of median frequency was faster than H/L, and relaxation rates correlated with shortening velocity and mechanical power of inspiratory ribcage muscles; however, with different time courses. Time constant of the inspiratory ribcage muscles during fatigue and recovery is not uniform (i.e., different inspiratory muscles may have different underlying mechanisms of fatigue), and MRR, ½RT, and τ are not only useful predictors of inspiratory ribcage muscle recovery but may also share common underlying mechanisms with shortening velocity.

scholarly journals Spatial Patterns in Different Stages of Regeneration after Clear-Cutting of a Black Locust Forest in Central China

Forests ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 1066
Author(s):  
Zhang ◽  
Shen ◽  
Yang ◽  
Ma ◽  
Duan ◽  
...  
Keyword(s):  
Spatial Patterns ◽  
Stand Structure ◽  
Robinia Pseudoacacia ◽  
Spatial Relation ◽  
Dispersal Limitation ◽  
Central China ◽  
Variance Gamma ◽  
Clear Cutting ◽  
Variance Gamma Process ◽  
Underlying Mechanisms

Estimating underlying mechanisms and dynamics from observed tree patterns can provide guidance for plantation management. Robinia pseudoacacia can reproduce via clonally produced ramets, leading to a complex distribution of stems. Three second generation plots and three third generation plots (each plot 50 m × 50 m) were established across a wide age range after clear-cutting in a Robinia pseudoacacia plantation in central China. We measured spatial coordinates, diameter at breast height (DBH) or diameter at basal stem, and heights of all recruits, as well as the coordinates and base diameter of all stumps, in six plots. The spatial pattern in different plots and the spatial relation between stumps and regenerations after clear-cutting were analyzed. To estimate the underlying processes of the observed patterns, we fitted Matérn and Variance-Gamma cluster processes to the observed dataset. The results revealed that the percentage of ramets from stumps decreasing with age in the two types of stands (from 40.4% to 30.1%, from 57.6% to 35.7%), and trees exhibited an aggregated distribution in all plots, but the degree of aggregation exhibited a decreasing trend with age, and aggregation occurred at different scale. Furthermore, a large proportion of ramets had their nearest neighbor at a short distance (<1 m) based on analysis of the nearest neighbour function. The bivariate analysis revealed that the spatial relation between stumps and ramets changed with age, and a repulsion trend was found between them in all the six plots. The Variance-Gamma process with covariate of Cartesian coordinates fitted the observed patterns better than others. The observed pattern was likely driven by root dispersal limitation, seed dispersal limitation, human disturbance, and intraspecific competition. Spatial patterns are important characteristics in forest stand structure, and understanding the pattern change and its underlying mechanisms could allow for better timing of artificial disturbances to optimize stand structure and promote stand growth.

Distinct successional patterns and processes of free‐living and particle‐attached bacterial communities throughout a phytoplankton bloom

2020 ◽  
Vol 65 (8) ◽  
pp. 1363-1375 ◽  
Author(s):  
Huimin Xu ◽  
Dayong Zhao ◽  
Jin Zeng ◽  
Congcong Jiao ◽  
Zhongbo Yu ◽  
...  
Keyword(s):  
Bacterial Communities ◽  
Phytoplankton Bloom ◽  
Free Living ◽  
Patterns And Processes

scholarly journals Early Stage Root-Associated Fungi Show a High Temporal Turnover, but Are Independent of Beech Progeny

2020 ◽  
Vol 8 (2) ◽  
pp. 210 ◽  
Author(s):  
Kezia Goldmann ◽  
Silke Ammerschubert ◽  
Rodica Pena ◽  
Andrea Polle ◽  
Bin-Wei Wu ◽  
...  
Keyword(s):  
High Throughput Sequencing ◽  
Early Stage ◽  
European Beech ◽  
Fungal Species ◽  
Fungal Communities ◽  
Transplant Experiment ◽  
Fungal Community Structure ◽  
Temporal Turnover ◽  
One Year ◽  
The Impact

The relationship between trees and root-associated fungal communities is complex. By specific root deposits and other signal cues, different tree species are able to attract divergent sets of fungal species. Plant intraspecific differences can lead to variable fungal patterns in the root’s proximity. Therefore, within the Beech Transplant Experiment, we analyzed the impact of three different European beech ecotypes on the fungal communities in roots and the surrounding rhizosphere soil at two time points. Beech nuts were collected in three German sites in 2011. After one year, seedlings of the different progenies were out-planted on one site and eventually re-sampled in 2014 and 2017. We applied high-throughput sequencing of the fungal ITS2 to determine the correlation between tree progeny, a possible home-field advantage, plant development and root-associated fungal guilds under field conditions. Our result showed no effect of beech progeny on either fungal OTU richness or fungal community structure. However, over time the fungal OTU richness in roots increased and the fungal communities changed significantly, also in rhizosphere. In both plant compartments, the fungal communities displayed a high temporal turnover, indicating a permanent development and functional adaption of the root mycobiome of young beeches.

Low Frequency Music Slows Heart Rate and Decreases Sympathetic Activity

2018 ◽  
Vol 10 (4) ◽  
pp. 180 ◽  
Author(s):  
James D. Halbert ◽  
Debra R. Van Tuyll ◽  
Carl Purdy ◽  
Guang Hao ◽  
Steven Cauthron ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Sympathetic Activity ◽  
Stress Condition ◽  
Mental Arithmetic ◽  
Low Frequency ◽  
Cvd Risk ◽  
Beneficial Effects ◽  
Main Effect ◽  
Underlying Mechanisms

Objectives: Increasing blood pressure (BP) increases the risk of developing cardiovascular disease (CVD). Lower frequency music may lower BP and heart rate (HR), therefore, decreases the CVD risk. Methods: Participants were 16 high BP individuals aged 20 to 50 years. The protocol consisted of 2 visits (experimental & control). Music was tuned between 440 Hz and 432 Hz, and the frequencies changed every 10 minutes. HR variability, diastolic function, oxytocin, and amylase were recorded at each phase. An (ANOVA) was used to examine the effects of music. Results: Mental arithmetic significantly increased BP and HR (all ps<0.01). There were significant differences between the stress condition and all other conditions, all p’s < .02. There was a significant main effect for Music Order, F (1, 6) = 6.23, p = .047, ƞp2= .51, β = .55. Participants had lower HR listening to 432 Hz music (M = -7.20, se = 2.47) than 440 Hz music (M = -5.33, se = 2.71), t(7) = 2.53, p = .04, d ‘ = .41. Conclusion: Listening to low frequency music has cardiovascular benefits including slowing heart rate and promoting relaxation. Further study is needed to determine the underlying mechanisms of music induced beneficial effects.

scholarly journals Wood ant assemblages of Formica rufa group on lake islands and in mainland woodland in Central Finland

2018 ◽  
Vol 29 (1) ◽  
pp. 21-29 ◽  
Author(s):  
Jouni Sorvari
Keyword(s):  
Species Richness ◽  
Occurrence Probability ◽  
Island Size ◽  
Formica Rufa ◽  
Wood Ants ◽  
Formica Rufa Group ◽  
Species Area ◽  
Island Community ◽  
Species Area Relationship ◽  
Formica Lugubris

Associations of island size and isolation on the occurrence and species richness of five wood ant species of the Formica rufa group (F. rufa, F. aquilonia, F. lugubris, F. polyctena and F. pratensis) was tested in the Lake Konnevesi archipelago in Central Finland. In addition, the species composition was compared to that of mainland forests of the same region. Island isolation had no associations with the wood ant occurrence in this archipelago, but for most species, increasing island size was positively associated with the occurrence probability. According to the findings among the five species, Formica lugubris is the best adapted for insular living. There was a positive species–area relationship as the species richness of wood ants increased with an increasing island size. The island community of wood ants was dominated by colonies of the monogynous (single queen) species whereas the mainland community was dominated by those of polygynous (multiple queen) species.

scholarly journals A Synergistic Bactericidal Effect of Low-Frequency and Low-Intensity Ultrasound Combined with Levofloxacin-Loaded PLGA Nanoparticles on M. Smegmatis in Macrophages

2020 ◽  
Author(s):  
Shuang Xie ◽  
Gangjing Li ◽  
Yuru Hou ◽  
Min Yang ◽  
Fahui Li ◽  
...  
Keyword(s):  
Cell Structure ◽  
Low Frequency ◽  
Ultrasound Irradiation ◽  
Average Diameter ◽  
Bactericidal Effect ◽  
Plga Nanoparticles ◽  
Low Intensity ◽  
Low Intensity Ultrasound ◽  
Underlying Mechanisms

Abstract Purpose: Tuberculosis (TB) is a highly infectious disease caused by Mycobacterium tuberculosis (Mtb), which often parasites in macrophages. This study is performed to investigate the bactericidal effect and underlying mechanisms of low-frequency and low-intensity ultrasound (LFLIU) combined with levofloxacin-loaded PLGA nanoparticles (LEV-NPs) on M. smegmatis (a surrogate of Mtb) in macrophages.Methods and results: The LEV-NPs were prepared using a double emulsification method. The average diameter, zeta potential, polydispersity index, morphology, and drug release efficiency in vitro of the LEV-NPs were investigated. M. smegmatis in macrophages was treated using the LEV-NPs combined with 42 kHz ultrasound irradiation at an intensity of 0.13 W/cm2 for 10 min. The results showed that ultrasound significantly promoted the phagocytosis of nanoparticles by macrophages (p < 0.05). In addition, further ultrasound combined with the LEV-NPs promoted the production of reactive oxygen species (ROS) in macrophage , and the apoptosis rate of the macrophages was significantly higher than that of the control (p < 0.05). The transmission electronic microscope showed that the cell wall of M. smegmatis was ruptured, the cell structure was incomplete, and the bacteria received severe damage in the ultrasound combined with the LEV-NPs group. Activity assays showed that ultrasound combined with the LEV-NPs exhibited a 10-fold higher antibacterial activity against M. smegmatis residing inside macrophages compared with the free drug.Conclusion: These data demonstrated that ultrasound combined with LEV-NPs has great potential as a therapeutic agent for TB.

Turnover is replaced by nestedness with increasing geographical distance in bacterial communities of coastal shallow lakes

2020 ◽  
Vol 71 (9) ◽  
pp. 1086
Author(s):  
Marla Sonaira Lima ◽  
Fabiana Schneck ◽  
Ng Haig They ◽  
Luciane Oliveira Crossetti ◽  
Juliana Elisa Bohnenberger ◽  
...  
Keyword(s):  
Shallow Lakes ◽  
Bacterial Communities ◽  
Local Environment ◽  
Dispersal Limitation ◽  
Geographical Distance ◽  
Environmental Filters ◽  
Species Sorting ◽  
Relative Contribution ◽  
Β Diversity ◽  
The Relationship

In this study we measured the relative contribution of two components of β-diversity, turnover and nestedness, of bacterioplankton among 25 shallow lakes in southern Brazil and tested their relationship with local (environment, chlorophyll-a and biomass of phytoplanktonic classes) and landscape variables, as well as geographical distance. We predicted that turnover would be the largest share of total β-diversity due to the variation of local characteristics among lakes. Further, we expected nestedness to increase at the expense of turnover with increasing geographical distance among lakes due to dispersal limitation. The results indicated a higher contribution of turnover than nestedness to total β-diversity, which was driven by local factors. When the relationship between β-diversity components and the spatial extent between each lake and all other lakes was considered, turnover was replaced by nestedness with increasing geographical distance for 8 (the furthermost lakes) of the 25 lakes likely because of a combination of decreasing dispersal due to distance and richness differences due to wind-driven mass effects. The results of this study suggest a role for nestedness as an indicator of dispersal limitation owing to geographical distance and wind dispersal, and for turnover as an indicator of species sorting because of environmental filters for these freshwater bacterial communities.

Sign in / Sign up

Export Citation Format

Share Document