Biology subjects

Amiri, H.

Publications and source records attributed to Amiri, H..

3 recordsLinked to original sources

bioRxiv2023

Accelerated Aging after Traumatic Brain Injury: an ENIGMA Multi-Cohort Mega-Analysis

ObjectiveThe long-term consequences of traumatic brain injury (TBI) on brain structure remain uncertain. In light of current evidence that even a single significant brain injury event increases the risk of dementia, brain-age estimation could provide a novel and efficient indexing of the long-term consequences of TBI. Brain-age procedures use predictive modeling to calculate brain-age scores for an individual using MRI data. Complicated mild, moderate and severe TBI (cmsTBI) is associated with a higher predicted (brain) age difference (PAD), but the progression of PAD over time remains unclear. Here we sought to examine whether PAD increases as a function of time since injury (TSI). MethodsAs part of the ENIGMA Adult Moderate and Severe (AMS)-TBI working group, we examine the largest TBI sample to date (n=343), along with controls, for a total sample size of 540, to reproduce and extend prior findings in the study of TBI brain age. T1w-MRI data were aggregated across 7 cohorts and brain age was established using a similar brain age algorithm to prior work in TBI. ResultsFindings show that PAD widens with longer TSI, and there was evidence for differences between sexes in PAD, with men showing more advanced brain age. We did not find evidence supporting a link between PAD and cognitive performance. InterpretationThis work provides evidence that changes in brain structure after cmsTBI are dynamic, with an initial period of change, followed by relative stability, eventually leading to further changes in the decades after a single cmsTBI.

neuroscience↗

bioRxiv2023

Secondary Structure Detection Through Direct Nanopore RNA Sequencing

Eukaryotic reverse transcriptases (RTs) can have essential or deleterious roles in normal human physiology and disease. Compared to well-studied helicases, it remains unclear how RTs overcome the ubiquitous RNA structural barriers during reverse transcription. Herein, we describe the development of a Mycobacterium smegmatis porin A (MspA) nanopore technique to sequence RNA to quantify the single-molecule kinetics of an RT from Bombyx mori with single-nucleotide resolution. By establishing a quadromer map that correlates RNA sequence and MspA ion current, we were able to quantify the RTs dwell time at every single nucleotide step along its RNA template. By challenging the enzyme with various RNA structures, we found that during cDNA synthesis the RT can sense and actively destabilize RNA structures 11-12 nt downstream of its front boundary. The ability to sequence single molecules of RNA with nanopores paves the way to investigate the single-nucleotide activity of other processive RNA translocases.

biophysics↗

bioRxiv2019

Overexpression of Medicago sativa glutamate-semialdehyde aminotransferase (GSA) gene in tobacco increased photosynthesis efficiency

To investigate the effect of increased glutamate-semialdehyde aminotransferase (GSA) on photosynthetic capacity and growth, tobacco (Nicoliana tabacum L. Xanti) plants with increased levels of glutamate-semialdehyde aminotransferase protein were produced. This was achieved using a cassette composed of a full-length Medicago sative cDNA under the control of the cauliflower mosaic virus 35S promoter. The results revealed distinct impacts of GSA activity on photosynthesis rate and growth in GSA over expression tobacco plants. In transgenic plants with increased GSA activity, an increase in soluble and insoluble sugars accumulation was evident. Total biomass, leaf area, plant height and internode 3-4 were increased in GSA sense plants, compared with equivalent wild-type tobacco plants. Moreover, transgenic tobacco plants with increased GSA activity exhibit higher levels of 5-aminolevulinic acid (ALA) accumulation and increased in content of chlorophyll and carotenoids pigments. Collectively, our data suggest that higher level of GSA activity gives an advantage to photosynthesis, growth in tobacco plants. This work also provides a case study that an individual enzyme in the biosynthesis of chlorophyll pathway may serve as a useful target for genetic engineering to improve photosynthesis and growth in plants.\n\nHighlightOverexpression of glutamate-semialdehyde aminotransferase (GSA) increase photosynthetic capacity, growth in tobacco.

plant biology↗