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Natural genetic transformation of Streptococcus pneumoniae, an important human pathogen, mediates horizontal gene transfer for the development of drug resistance, modulation of carriage and virulence traits, and evasion of host immunity. Transformation frequency differs greatly among pneumococcal clinical isolates, but the molecular basis and biological importance of this interstrain variability remain unclear. In this study, we characterized the transformation frequency and other associated phenotypes of 208 S. pneumoniae clinical isolates representing at least 30 serotypes. While the vast majority of these isolates (94.7%) were transformable, the transformation frequency differed by up to 5 orders of magnitude between the least and most transformable isolates. The strain-to-strain differences in transformation frequency were observed among many isolates producing the same capsule types, indicating no general association between transformation frequency and serotype. However, a statistically significant association was observed between the levels of transformation and colonization fitness/virulence in the hypertransformable isolates. Although nontransformable mutants of all the selected hypertransformable isolates were significantly attenuated in colonization fitness and virulence in mouse infection models, such mutants of the strains with relatively low transformability had no or marginal fitness phenotypes under the same experimental settings. This finding strongly suggests that the pneumococci with high transformation capability are "addicted" to a "hypertransformable" state for optimal fitness in the human host. This work has thus provided an intriguing hint for further investigation into how the competence system impacts the fitness, virulence, and other transformation-associated traits of this important human pathogen.
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http://dx.doi.org/10.1128/IAI.00097-16 | DOI Listing |
Biophys J
September 2025
Laboratory for Multiscale Mechanics and Medical Science, State Key Laboratory for Strength and Vibration of Mechanical Structures, School of Aerospace Engineering, Xi'an Jiaotong University, Xi'an, 710049, China. Electronic address:
The mechanical properties of cells are crucial for elucidating various physiological and pathological processes. Cells are found to exhibit a universal power-law rheological behavior at low frequencies. While they behave in a different manner at high frequency regimes, which leaves the transition region largely unexplored.
View Article and Find Full Text PDFAging Cell
September 2025
San Francisco Coordinating Center, California Pacific Medical Center Research Institute, San Francisco, California, USA.
Entropy, characterized by increased disorder throughout biological systems, can be quantified by homeostatic dysregulation (HD). One potential measure of HD is the dispersion of points from a normal value, approximated at the individual level by Mahalanobis distance (D). We hypothesized that greater HD in electrocardiogram (ECG) would also reflect greater HD in the musculoskeletal system which, in turn, would be associated with age and manifest as an increased risk of fracture independently of age, bone mineral density (BMD), and history of fracture.
View Article and Find Full Text PDFJDR Clin Trans Res
September 2025
School of Dentistry, Faculty of Health and Behavioural Sciences, The University of Queensland, Brisbane, Queensland, Australia.
Objectives: Socioeconomic status (SES) has a significant effect on the burden of early childhood caries (ECC), yet addressing SES disparities remains challenging. This study aimed to identify and quantify the most impactful mediator linking SES effect to the occurrence of ECC using advanced causal mediation analysis, to inform targeted interventions that reduce SES-related disparities in ECC.
Methods: Data were drawn from the Study of Mothers' and Infants' Life Events, a cohort of 2,182 mother-child dyads recruited from Adelaide's 3 largest public hospitals (2013-2014).
J Am Chem Soc
September 2025
Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States.
Alternating current (AC) electrolysis offers a promising strategy for modulating redox states in metal-catalyzed reactions, yet its mechanistic basis remains poorly understood. Here, we uncover how AC frequency synchronizes with key steps in a Ni-catalyzed cross-coupling cycle to control product selectivity between C-N and C-C coupling. We show that optimal C-N selectivity arises from minimizing the exposure of a key intermediate, Ni(Ar)Br, to reducing conditions that otherwise promote off-cycle Ni species and undesired C-C homocoupling.
View Article and Find Full Text PDFJ Neurosci Methods
September 2025
Department of Computer Science and Engineering, IIT (ISM) Dhanbad, Dhanbad, 826004, Jharkhand, India. Electronic address:
Background: Interpretation of motor imagery (MI) in brain-computer interface (BCI) applications is largely driven by the use of electroencephalography (EEG) signals. However, precise classification in stroke patients remains challenging due to variability, non-stationarity, and abnormal EEG patterns.
New Methods: To address these challenges, an integrated architecture is proposed, combining multi-domain feature extraction with evolutionary optimization for enhanced EEG-based MI classification.