Hasil untuk "Biology"

P. Raven, R. Evert, S. E. Eichhorn

Grace Jordison

No wonder you activities are, reading will be always needed. It is not only to fulfil the duties that you need to finish in deadline time. Reading will encourage your mind and thoughts. Of course, reading will greatly develop your experiences about everything. Reading molecular biology of the gene is also a way as one of the collective books that gives many advantages. The advantages are not only for you, but for the other peoples with those meaningful benefits.

D. Brooks, P. Price

G. Moment, A. Woodhead, A. D. Blackett et al.

J. Jackson, L. W. Buss, R. E. Cook et al.

M. G. Mullins, A. Bouquet, L. Williams

B. Halliwell

P. J. Newman

W. Weckwerth

A. Weston, L. Hood

M. Roco

Domitilla Del Vecchio, A. Ninfa, Eduardo Sontag

Modularity plays a fundamental role in the prediction of the behavior of a system from the behavior of its components, guaranteeing that the properties of individual components do not change upon interconnection. Just as electrical, hydraulic, and other physical systems often do not display modularity, nor do many biochemical systems, and specifically, genetic networks. Here, we study the effect of interconnections on the input–output dynamic characteristics of transcriptional components, focusing on a property, which we call ‘retroactivity’, that plays a role analogous to non‐zero output impedance in electrical systems. In transcriptional networks, retroactivity is large when the amount of transcription factor is comparable to, or smaller than, the amount of promoter‐binding sites, or when the affinity of such binding sites is high. To attenuate the effect of retroactivity, we propose a feedback mechanism inspired by the design of amplifiers in electronics. We introduce, in particular, a mechanism based on a phosphorylation–dephosphorylation cycle. This mechanism enjoys a remarkable insulation property, due to the fast timescales of the phosphorylation and dephosphorylation reactions.

Angie Nguyen, Lucas J. Ustick, Alyse A. Larkin et al.

ABSTRACT Photoautotrophic diazotrophs, specifically the genera Trichodesmium and UCYN-A, play a pivotal role in marine nitrogen cycling through their capacity for nitrogen fixation. Despite their global distribution, the microdiversity and environmental drivers of these diazotrophs remain underexplored. This study provides a comprehensive analysis of the global diversity and distribution of Trichodesmium and UCYN-A using the nitrogenase gene (nifH) as a genetic marker. We sequenced 954 samples from the Pacific, Atlantic, and Indian Oceans as part of the Bio-GO-SHIP project. Our results reveal significant phylogenetic and biogeographic differences between and within the two genera. Trichodesmium exhibited greater microdiversity compared to UCYN-A, with clades showing region-specific distribution. Trichodesmium clades were primarily influenced by temperature and nutrient availability. They were particularly frequent in regions of phosphorus stress. In contrast, UCYN-A was most frequently observed in regions experiencing iron stress. UCYN-A clades demonstrated more homogeneous distributions, with a single sequence variant within the UCYN-A1 clade dominating across varied environments. The biogeographic patterns and environmental correlations of Trichodesmium and UCYN-A highlight the role of microdiversity in their ecological adaptation and reflect their different ecological strategies. These findings underscore the importance of characterizing the global patterns of fine-scale genetic diversity to better understand the functional roles and distribution of marine nitrogen-fixing photoautotrophs.IMPORTANCEThis study provides insights into the global diversity and distribution of nitrogen-fixing photoautotrophs, specifically Trichodesmium and UCYN-A. We sequenced 954 oceanic samples of the nifH nitrogenase gene and uncovered significant differences in microdiversity and environmental associations between these genera. Trichodesmium showed high levels of sequence diversity and region-specific clades influenced by temperature and nutrient availability. In contrast, UCYN-A exhibited a more uniform distribution, thriving in iron-stressed regions. Quantifying these fine-scale genetic variations enhances our knowledge of their ecological roles and adaptations, emphasizing the need to characterize the genetic diversity of marine nitrogen-fixing prokaryotes.

Peidong Guo, Yueheng Liu, Luyin Tan et al.

Nowadays, many of the top-selling video games include options to purchase loot boxes as paid virtual items. As research progressed, loot boxes have been found to have similar characteristics to gambling, and there has been an ongoing debate as to whether loot boxes can be defined as gambling. In order to better study loot boxes, psychometrically meaningful scales are necessary. The Risky Loot Box Index (RLI) was developed by Brooks and Clark, which is the most commonly used tool to assess the use of loot boxes. This study aimed to translate the original RLI into Chinese and evaluate its psychometric properties. Two samples were recruited through online gaming forums (n = 143) and offline internet cafes (n = 236). An exploratory factor analysis of the online sample yielded a one-dimensional nine-item model, with the factor focused on risky behaviors associated with loot boxes. The confirmatory factor analysis carried out on the offline sample corroborated the results obtained from the exploratory factor analysis, and the Chinese version of the RLI displays satisfactory psychometric properties. Furthermore, the Problem Gambling Severity Index (r = 0.57, P < 0.001) and the Internet Gaming Disorder Scale-Short Form (r = 0.67, P < 0.001) were found to be significantly associated with the RLI. We also found that players with high RLI scores may have higher levels of anxiety and depression, and they were more willing to spend money on loot boxes, with some spending nearly all their earnings. Interestingly, no significant correlations between age, gender, education, or income level, and the RLI were found.

J. Fisher, T. Henzinger

Viviana I Pérez, Felipe Sierra

This chapter briefly summarizes what we currently know about some of the biological changes that accompany aging, and then tries to predict which of these may be the most relevant to the onset of age-related cardiac pathology, and the ultimate need for cardiothoracic surgery in older persons. Although cardiovascular diseases are now the major cause of mortality in developed countries, and age is a major risk factor for many of these diseases, it is still not clear just which age-related changes are the most critical in affecting longevity or the risk of dying as a result of cardiovascular pathology.

E. Kutter, A. Sulakvelidze

Anna Ulldemolins, Maria Narciso, Maria Narciso et al.

Introduction: Aging induces functional and structural changes in the lung, characterized by a decline in elasticity and diminished pulmonary remodeling and regenerative capacity. Emerging evidence suggests that most biomechanical alterations in the lung result from changes in the composition of the lung extracellular matrix (ECM), potentially modulating the behavior of pulmonary cells and increasing the susceptibility to chronic lung diseases. Therefore, it is crucial to investigate the mechanical properties of the aged lung. This study aims to assess the mechanical alterations in the lung ECM due to aging at both residual (RV) and functional (FV) lung volumes and to evaluate their effects on the survival and proliferation of mesenchymal stromal cells (MSCs).Methods: The lungs from young (4-6-month-old) and aged (20-24-month-old) mice were inflated with optimal cutting temperature compound to reach FV or non-inflated (RV). ECM proteins laminin, collagen I and fibronectin were quantified by immunofluorescence and the mechanical properties of the decellularized lung sections were assessed using atomic force microscopy. To investigate whether changes in ECM composition by aging and/or mechanical properties at RV and FV volumes affects MSCs, their viability and proliferation were evaluated after 72 h.Results: Laminin presence was significantly reduced in aged mice compared to young mice, while fibronectin and collagen I were significantly increased in aged mice. In RV conditions, the acellular lungs from aged mice were significantly softer than from young mice. By contrast, in FV conditions, the aged lung ECM becomes stiffer than that of in young mice, revealing that strain hardening significantly depends on aging. Results after MSCs recellularization showed similar viability and proliferation rate in all conditions.Discussion: This data strongly suggests that biomechanical measurements, especially in aging models, should be carried out in physiomimetic conditions rather than following the conventional non-inflated lung (RV) approach. The use of decellularized lung scaffolds from aged and/or other lung disease murine/human models at physiomimetic conditions will help to better understand the potential role of mechanotransduction on the susceptibility and progression of chronic lung diseases, lung regeneration and cancer.

Jinkun Ye, Yuhui Ji, Jinfeng Wang et al.

Specific leaf area (SLA) and leaf dry matter content (LDMC) are key leaf functional traits often used to reflect plant resource utilization strategies and predict plant responses to environmental changes. In general, grassland plants at different elevations exhibit varying survival strategies. However, it remains unclear how grassland plants adapt to changes in elevation and their driving factors. To address this issue, we utilized SLA and LDMC data of grassland plants from 223 study sites at different elevations in China, along with climate and soil data, to investigate variations in resource utilization strategies of grassland plants along different elevational gradients and their dominant influencing factors employing linear mixed-effects models, variance partitioning method, piecewise Structural Equation Modeling, etc. The results show that with increasing elevation, SLA significantly decreases, and LDMC significantly increases (P &lt; 0.001). This indicates different resource utilization strategies of grassland plants across elevation gradients, transitioning from a “faster investment-return” at lower elevations to a “slower investment-return” at higher elevations. Across different elevation gradients, climatic factors are the main factors affecting grassland plant resource utilization strategies, with soil nutrient factors also playing a non-negligible coordinating role. Among these, mean annual precipitation and hottest month mean temperature are key climatic factors influencing SLA of grassland plants, explaining 28.94% and 23.88% of SLA variation, respectively. The key factors affecting LDMC of grassland plants are mainly hottest month mean temperature and soil phosphorus content, with relative importance of 24.24% and 20.27%, respectively. Additionally, the direct effect of elevation on grassland plant resource utilization strategies is greater than its indirect effect (through influencing climatic and soil nutrient factors). These findings emphasize the substantive impact of elevation on grassland plant resource utilization strategies and have important ecological value for grassland management and protection under global change.