In-house Production Method for DNA Ladders to Determine Nucleotide Fragment Sizes up to 1500 Base Pairs

The human genome project was recently completed after running for 15 years and revealed the presence of 30,000 genes in the human genome with a total nucleotide length of 3.2 billion base pairs (bp). Many novel methods and techniques have been developed in the field of molecular biology and molecular genetics as a result of intensive research, where basic analysis is impossible without the use of DNA size markers or DNA ladders. This research aimed to establish an in-house method to produce DNA size markers detecting up to 1500 bp size. DNA size markers are commonly used consumables in molecular biology laboratories. In this study, we report preparation of a DNA size marker consisting of 12 fragments from 100 to 1500 bp. DNA fragments were amplified by PCR and PCR products were then ligated in the cloning vector pDYNE TA V2. Our procedure for DNA size marker production could be simple, time saving, and inexpensive.nbs

Single-cell analysis reveals the continuum of human lympho-myeloid progenitor cells.

The hierarchy of human hemopoietic progenitor cells that produce lymphoid and granulocytic-monocytic (myeloid) lineages is unclear. Multiple progenitor populations produce lymphoid and myeloid cells, but they remain incompletely characterized. Here we demonstrated that lympho-myeloid progenitor populations in cord blood - lymphoid-primed multi-potential progenitors (LMPPs), granulocyte-macrophage progenitors (GMPs) and multi-lymphoid progenitors (MLPs) - were functionally and transcriptionally distinct and heterogeneous at the clonal level, with progenitors of many different functional potentials present. Although most progenitors had the potential to develop into only one mature cell type ('uni-lineage potential'), bi- and rarer multi-lineage progenitors were present among LMPPs, GMPs and MLPs. Those findings, coupled with single-cell expression analyses, suggest that a continuum of progenitors execute lymphoid and myeloid differentiation, rather than only uni-lineage progenitors' being present downstream of stem cells.MRC (MHU Award G1000729, MRC Disease Team Award 4050189188), CRUK (Program Grant to PV C7893/A12796, CRUK program grant to BG C1163/A21762), Bloodwise (Specialist Program 13001 and Project grant to 12019), an MRC PhD studentship (F.H. & Z.A.), The MRC Single Cell Award (MR/M00919X/1) to the WIMM and the Oxford Partnership Comprehensive Biomedical Research Centre (NIHR BRC Funding scheme). We thank the High-Throughput Genomics Group at the Wellcome Trust Centre for Human Genetics (funded by Wellcome Trust grant reference 090532/Z/09/Z) for generation of sequencing data. R.M. was supported by National Institutes of Health grants R01CA188055 and U01HL099999, New York Stem Cell Foundation Robertson Investigator and Leukemia and Lymphoma Society Scholar Award. A.R. was supported by an Erwin-Schroedinger Research fellowship from the Austrian Science Fund (FWF)

Coronal Heating as Determined by the Solar Flare Frequency Distribution Obtained by Aggregating Case Studies

Flare frequency distributions represent a key approach to addressing one of the largest problems in solar and stellar physics: determining the mechanism that counter-intuitively heats coronae to temperatures that are orders of magnitude hotter than the corresponding photospheres. It is widely accepted that the magnetic field is responsible for the heating, but there are two competing mechanisms that could explain it: nanoflares or Alfv\'en waves. To date, neither can be directly observed. Nanoflares are, by definition, extremely small, but their aggregate energy release could represent a substantial heating mechanism, presuming they are sufficiently abundant. One way to test this presumption is via the flare frequency distribution, which describes how often flares of various energies occur. If the slope of the power law fitting the flare frequency distribution is above a critical threshold, $\alpha=2$ as established in prior literature, then there should be a sufficient abundance of nanoflares to explain coronal heating. We performed $>$600 case studies of solar flares, made possible by an unprecedented number of data analysts via three semesters of an undergraduate physics laboratory course. This allowed us to include two crucial, but nontrivial, analysis methods: pre-flare baseline subtraction and computation of the flare energy, which requires determining flare start and stop times. We aggregated the results of these analyses into a statistical study to determine that $\alpha = 1.63 \pm 0.03$. This is below the critical threshold, suggesting that Alfv\'en waves are an important driver of coronal heating.Comment: 1,002 authors, 14 pages, 4 figures, 3 tables, published by The Astrophysical Journal on 2023-05-09, volume 948, page 7