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Topic Review
Alternative Splicing Mechanisms in Tumors
Alternative pre-mRNA splicing is a process that allows for the generation of an extremely diverse proteome from a much smaller number of genes. In this process, non-coding introns are excised from primary mRNA and coding exons are joined together. Different combinations of exons give rise to alternative versions of a protein.
  • 299
  • 06 Jun 2023
Topic Review
Alternative Splicing of hTERT
Alternative splicing (AS) of human telomerase catalytic subunit (hTERT, human telomerase reverse transcriptase) pre-mRNA strongly regulates telomerase activity. Several proteins can regulate AS in a cell type-specific manner and determine the functions of cells. In addition to being involved in telomerase activity regulation, AS provides cells with different splice variants that may have alternative biological activities. The modulation of telomerase activity through the induction of hTERT AS is involved in the development of different cancer types and embryos, and the differentiation of stem cells. Regulatory T cells may suppress the proliferation of target human and murine T and B lymphocytes and NK cells in a contact-independent manner involving activation of TERT AS. 
  • 620
  • 18 May 2021
Topic Review
Alternative System for Secondary Metabolite Production
Medicinal plants are rich sources of bioactive compounds widely used as medicaments, food additives, perfumes, and agrochemicals. These secondary compounds are produced under stress conditions to carry out physiological tasks in plants. Secondary metabolites have a complex chemical structure with pharmacological properties. The widespread use of these metabolites in a lot of industrial sectors has raised the need to increase the production of secondary metabolites. Biotechnological methods of cell culture allow the conservation of plants, as well as the improvement of metabolite biosynthesis and the possibility to modify the synthesis pathways.
  • 537
  • 11 Jan 2023
Topic Review
Alternatively Spliced Isoforms in MAPK Signaling
The mitogen-activated protein kinase (MAPK) cascades are key signaling components  that transmit signals to many cellular processes. Each of the cascades operates by a sequential activation of protein kinases organized in three or more tiers that provide a seemingly linear signal transmission. However, the cellular effects regulated by each cascade may vary significantly. To achieve these diverse effects, the specificity of each cascade is extended by distinct regulators.  Here we describe the importance of having distinct components in each tier of the cascades, particularly alternatively spliced isoforms of the MAPK components. This mode of regulation extends the cascade’s specificity and allows accurate, fine-tuned signaling outcomes that lead to proper cell fates. 
  • 561
  • 28 Jan 2022
Topic Review
Alternatives to Evolution by Natural Selection
Alternatives to evolution by natural selection, also described as non-Darwinian mechanisms of evolution, have been proposed by scholars investigating biology since classical times to explain signs of evolution and the relatedness of different groups of living things. The alternatives in question do not deny that evolutionary changes over time are the origin of the diversity of life, nor deny that the organisms alive today share a common ancestor from the distant past (or ancestors, in some proposals); rather, they propose alternative mechanisms of evolutionary change over time, arguing against mutations acted on by natural selection as the most important driver of evolutionary change. (In most cases, they do not deny that mutations or natural selection occur, or that they play a role in evolutionary change, but instead deny that they are fully sufficient primary causes for the evidence of evolutionary change that is observed in the natural world.) This distinguishes them from certain other kinds of arguments that deny that large scale evolution of any sort has taken place, as in some forms of creationism, which do not propose alternative mechanisms of evolutionary change but instead deny that evolutionary change has taken place at all. Not all forms of creationism deny that evolutionary change takes places; notably, proponents of theistic evolution, such as the biologist Asa Gray, assert that evolutionary change does occur and is responsible for the history of life on Earth, with the proviso that this process has been influenced by a god or gods in some meaningful sense. Where the fact of evolutionary change was accepted but the mechanism proposed by Charles Darwin, natural selection, was denied, explanations of evolution such as Lamarckism, catastrophism, orthogenesis, vitalism, structuralism and mutationism (called saltationism before 1900) were entertained. Different factors motivated people to propose non-Darwinian mechanisms of evolution. Natural selection, with its emphasis on death and competition, did not appeal to some naturalists because they felt it immoral, leaving little room for teleology or the concept of progress in the development of life. Some who came to accept evolution, but disliked natural selection, raised religious objections. Others felt that evolution was an inherently progressive process that natural selection alone was insufficient to explain. Still others felt that nature, including the development of life, followed orderly patterns that natural selection could not explain. By the start of the 20th century, evolution was generally accepted by biologists but natural selection was in eclipse. Many alternative theories were proposed, but biologists were quick to discount theories such as orthogenesis, vitalism and Lamarckism which offered no mechanism for evolution. Mutationism did propose a mechanism, but it was not generally accepted. The modern synthesis a generation later claimed to sweep away all the alternatives to Darwinian evolution, though some have been revived as molecular mechanisms for them have been discovered.
  • 2.8K
  • 09 Oct 2022
Topic Review
Alum Pickering Emulsion to Improve Malaria Vaccine Efficacy
Malaria is a life-threatening global epidemic disease and has caused more than 400,000 deaths in 2019. To control and prevent malaria, the development of a vaccine is a potential method. An effective malaria vaccine should either combine antigens from all stages of the malaria parasite’s life cycle, or epitopes of multiple key antigens due to the complexity of the Plasmodium parasite. Malaria’s random constructed antigen-1 (M.RCAg-1) is one of the recombinant vaccines, which was selected from a DNA library containing thousands of diverse multi-epitope chimeric antigen genes. Moreover, besides selecting an antigen, using an adjuvant is another important procedure for most vaccine development procedures. Freund’s adjuvant is considered an effective vaccine adjuvant for malaria vaccine, but it cannot be used in clinical settings because of its serious side effects. Traditional adjuvants, such as alum adjuvant, are limited by their unsatisfactory immune effects in malaria vaccines, hence there is an urgent need to develop a novel, safe and efficient adjuvant. In recent years, Pickering emulsions have attracted increasing attention as novel adjuvant. In contrast to classical emulsions, Pickering emulsions are stabilized by solid particles instead of surfactant, having pliability and lateral mobility. In this study, we selected aluminum hydroxide gel (termed as “alum”) as a stabilizer to prepare alum-stabilized Pickering emulsions (ALPE) as a malaria vaccine adjuvant. In addition, monophosphoryl lipid A (MPLA) as an immunostimulant was incorporated into the Pickering emulsion (ALMPE) to further enhance the immune response. In vitro tests showed that, compared with alum, ALPE and ALMPE showed higher antigen load rates and could be effectively endocytosed by J774a.1 cells. In vivo studies indicated that ALMPE could induce as high antibody titers as Freund’s adjuvant. The biocompatibility study also proved ALMPE with excellent biocompatibility. These results suggest that ALMPE is a potential adjuvant for a malaria vaccine. 
  • 453
  • 02 Nov 2021
Topic Review
Aluminum Toxicity
Aluminum (Al) toxicity is a major environmental stress that inhibits plant growth and development in acidic soils. 
  • 818
  • 13 Apr 2021
Topic Review
Alveolar Bone Regeneration and Mesenchymal Stem Cells
Mesenchymal stem cells/stromal cells (MSCs), which have been applied in implantology and periodontology. MSCs, with their multilineage differentiation potential (differentiation into osteocytes, chondrocytes, adipocytes, muscle cells, and even neurocytes) are widely available from various tissues sources.
  • 558
  • 17 Nov 2021
Topic Review
Alveolar Epithelial Cells in Pulmonary Fibrosis
An important contributor to the development of idiopathic pulmonary fibrosis (IPF) is the alteration of the intracellular homeostasis of alveolar epithelial cells, which are mainly composed of alveolar type I epithelial cells (AT1), alveolar type II epithelial cells (AT2), as well as abnormal basaloid cells, resulting in aberrant epithelial repair, myofibroblast activation, and increased extracellular matrix deposition to form lung fibrosis
  • 577
  • 27 Feb 2023
Topic Review
Alveolar Macrophages
At the early stages of life development, alveoli are colonized by embryonic macrophages, which become resident alveolar macrophages (ResAM) and self-sustain by local division. Genetic and epigenetic signatures and, to some extent, the functions of ResAM are dictated by the lung microenvironment, which uses cytokines, ligand-receptor interactions, and stroma cells to orchestrate lung homeostasis. 
  • 723
  • 05 Nov 2021
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