We traced the sequence evolution of the active lineage of LINE-1 (L1) retrotransposons over the last approximately 25 Myr of human evolution. Five major families (L1PA5, L1PA4, L1PA3B, L1PA2, and L1PA1) of elements have succeeded each other as a single lineage. We found that part of the first open-reading frame (ORFI) had a higher rate of nonsynonymous (amino acid replacement) substitution than synonymous substitution during the evolution of the ancestral L1PA5 through the L1PA3B families. This segment encodes the coiled coil region of the protein-protein interaction domain of the ORFI protein (ORFIp). Statistical analysis of these changes indicates that positive selection had been acting on this region. In contrast, the coiled coil segment hardly changed during the evolution of the L1PA3B to the present L1PA1 family. Therefore, selective pressure on the coiled coil segment has changed over time. We suggest that the fast rate of amino acid replacement in the coiled coil segment reflects the adaptation of L1 either to a changing genomic environment or to host repression factors. In contrast, the second open-reading frame and the nucleic acid-binding domain of the first open-reading frame are extremely well conserved, attesting to the strong purifying selection acting on these regions.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1093/oxfordjournals.molbev.a003765 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Photon-counting CT imaging of a patient with coiled and untreated intracranial saccular aneurysms.
Neuroradiol J
January 2025
Department of Radiology and Radiological Science, Medical University of South Carolina, USA.
We describe a novel application of photon-counting detector CT (PCD-CT) in neurovascular imaging by harnessing the improved spatial resolution, attenuation of electronic noise, and reduction of metal artifacts. The presented case offers the unique challenge of high-quality imaging for the assessment of treated and untreated intracranial saccular aneurysms, in the setting of metal artifacts from embolization coils. Our goal was to explore optimized reconstruction parameters for ultra-high-resolution imaging (UHR) using a dedicated, sharp neurovascular kernel (Hv72) and the highest strength of quantum iterative reconstruction (QIR-4) for detailed characterization of the vasculature.
View Article and Find Full Text PDFUndocking of an extensive ciliary network induces proteostasis and cell fate switching resulting in severe primary ciliary dyskinesia.
Sci Transl Med
January 2025
Department of Cell Biology and Physiology, Washington University School of Medicine, Saint Louis, MO 63110, USA.
Article Synopsis
- Primary ciliary dyskinesia (PCD) is a rare genetic disorder linked to chronic respiratory issues, infertility, and problems with body asymmetry, primarily caused by mutations in the CCDC39 and CCDC40 genes.
- Researchers used advanced techniques to investigate how these genetic variants impact cellular functions beyond just causing cilia to stop moving.
- They discovered that the absence of CCDC39/CCDC40 creates a significant loss of over 90 ciliary structural proteins, leading to cilia dysfunction and other cellular issues, suggesting that gene therapy could potentially offer a new treatment strategy for PCD.
Sequential Growth of Quantized Peptide Brushes on Colloidal Gold.
Langmuir
January 2025
Department of Materials Science and Engineering, University of Delaware, Newark, Delaware 19716, United States.
We synthesized rigid, macromolecular brushes with well-defined and quantized brush lengths on a gold nanoparticle substrate by using a macromolecular "grafting from" approach. The macromonomers used in these brushes were thiol- and maleimide-functionalized peptide coiled coil "bundlemers" that fold into discrete 4 nm × 2 nm (length × diameter) cylindrical nanoparticles. With each added peptide macromonomer layer, brush thickness increased by approximately the length of a single bundlemer nanoparticle.
View Article and Find Full Text PDFHarmonic analysis and optimization for closed-loop superconducting shim coils of 7 T MRI magnet.
Med Phys
January 2025
Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, China.
Background: High-resolution brain imaging is crucial in clinical diagnosis and neuroscience, with ultra-high field strength MRI systems ( ) offering significant advantages for imaging neuronal microstructures. However, achieving magnetic field homogeneity is challenging due to engineering faults during the installation of superconducting strip windings and the primary magnet.
Purpose: This study aims to design and optimize active superconducting shim coils for a 7 T animal MRI system, focusing on the impact of safety margin, size, and adjustability of the second-order shim coils on the MRI system's optimization.
is a spermatid-specific gene required for spermatogenesis and male fertility.
Int J Dev Biol
January 2025
Faculty of Biochemistry and Molecular Medicine, University of Oulu, Finland.
Male infertility is a multifactorial condition for which the underlying causes frequently remain undefined. Genetic factors have long been associated with male fertility. However, many of them are poorly or not at all characterized and their biological functions are unknown.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!