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Population and Community: Count Variables
Published in Song S. Qian, Mark R. DuFour, Ibrahim Alameddine, Bayesian Applications in Environmental and Ecological Studies with R and Stan, 2023
Song S. Qian, Mark R. DuFour, Ibrahim Alameddine
One potential problem is that recruitment of different types of trees may vary by position. That is, there may be a type-position interaction. Including the interaction between type and position is equivalent to allowing the type effect to vary by position and the position effect to vary by type, or directly estimating the effect of the combined type-position variable:
Invariance
Published in Trevor G. Bond, Zi Yan, Moritz Heene, Applying the Rasch Model, 2020
Trevor G. Bond, Zi Yan, Moritz Heene
Despite the potential benefits that vertical scales have, appropriate caution should guide the design of vertical scales and the interpretation of results obtained from vertical scales. Researchers express concern about the validity of vertical scales (e.g., Lissitz & Huynh, 2003) due to possible threats including item position effect, and different curricula across grades. Wu (2009) also warned that results of vertical scales are largely dependent on the equating methodology used; this is likely a sign of the violation of model assumptions as well as misfit between the empirical data and the underlying model. In essence, our message remains clear and consistent: take a conservative approach and check regularly that the Rasch measurement properties of any assessments are maintained across samples and over time.
The Structure of Transcriptons and The Regulation of Transcription
Published in M. Gerald, M.D. Kolodny, Eukaryotic Gene Regulation, 2018
The existence of widespread multiple dispersed genes complicates the general scheme of genome organization. Mutations in these genes should not give phenotypic effects. On the other hand, the appearance of a new genetic element can influence the expression of a gene in the place where the translocated sequence has been inserted. It is interesting that if a usual structural gene is present in a certain intercalary heterochromatin site, the variegation position effect can be observed.182
Synthesis and discovery of the first potent proteolysis targeting chimaera (PROTAC) degrader of AIMP2-DX2 as a lung cancer drug
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2023
BoRa Lee, Dae Gyu Kim, Aram Lee, Young Mi Kim, Lianji Cui, Sunghoon Kim, Inhee Choi
To compare the position effect of the target, combinations of linkers and E3 ligase ligands were linked to position 2 of the target compound. Therefore, % inhibition of AIMP2-DX2 was measured for compounds 44–48, 51–53, and 54 (Table 2). Interestingly, AIMP2-DX2 degrader 44 showed more than 50% inhibitory activity although the length of the linker was only four atoms apart. Introducing one ether unit in the linker, the activity of compound 45 was further increased to 51.99%. However, longer linker lengths of the same series also led to a decrease in inhibitory activity similar to those attached to position 1. When carbonyl is presented next to an E3 ligase ligand rather than the target, the inhibitory activity of compounds 51–54 only presents a decrease in inhibitory activity with an increase in linker length. As a result, it was found that position 2 favours a shorter linker length, such as 4–6 atoms in length between the target and the E3 ligase ligand. In addition, like Position 1, the linker at position 2 also shows better activity with oxygen-containing linkers.
Modern vaccine strategies for emerging zoonotic viruses
Published in Expert Review of Vaccines, 2022
Atif Ahmed, Muhammad Safdar, Samran Sardar, Sahar Yousaf, Fiza Farooq, Ali Raza, Muhammad Shahid, Kausar Malik, Samia Afzal
The major strategies used to produce plant-based vaccines are nuclear, transplastomic, and viral vector transformation. Nuclear transformation is a very simple and widely used method because the foreign antigen is inserted into the nuclear genome. Agrobacterium tumefaciens or gene gun-mediated transformation is used for gene transfer. The nuclear transformation results in the continuous production of recombinant proteins. Additionally, nuclear transformation also results in the post-translational modification that takes place in eukaryotic systems [93,94]. But it is also coupled with some disadvantages including, lower expression level, gene silencing, position effect, and a chance of contamination. The chloroplast transformation overcomes some of the drawbacks of nuclear transformation, which has hampered commercialization as a plant-based recombinant vaccine. The desired gene (for an antigen) is directly introduced into the genome of the plant chloroplast by using a particle cannon. Most of the currently reported edible vaccines were produced by this method because of the high stability in gene expression. In chloroplasts, many viral antigens like rotavirus and canine parvovirus were expressed. Through overcoat and epic at technologies, several viruses such as cowpea mosaic virus (CPMV), alfalfa mosaic virus, tobacco mosaic virus (TMV), cauliflower mosaic virus (CaMV), tomato bushy stunt virus, and potato virus are designed to express the part of antigenic protein on their surface as reviewed in [95].
Telomerase: a good target in hepatocellular carcinoma? An overview of relevant preclinical data
Published in Expert Opinion on Therapeutic Targets, 2022
Maria Lina Tornesello, Anna Lucia Tornesello, Noemy Starita, Andrea Cerasuolo, Francesco Izzo, Luigi Buonaguro, Franco Maria Buonaguro
The main activity of telomerase is to restore tandem repeats (TTAGGG) undergoing erosion with each round of successive cell division and to stabilize the chromosome ends [37]. Long telomeres have the ability to form specific T-loops that hide and shield the ends of eukaryotic chromosomes and have an essential role in the regulation of genes located in the proximity of telomeres by a phenomenon termed telomere position effect (TPE) [38], TERT gene is located approximately 1.2 megabytes from the end of the human chromosome 5 (band 5p15.33) and a telomere position effect-over long distances (TPE-OLD) has been proposed in the regulation of telomerase expression. Specifically, Kim et al. (2016) have identified a spatial co-localization of 5p telomere sequences and the TERT locus in human cells with long telomeres and suppressed TERT expression [39]. On the other end, a spatial separation between at least one TERT allele and 5p end sequence was observed in TERT expressing cells with short telomeres in association with active histone marks and changes in DNA methylation in the TERT promoter region [39].