Increase in Mitochondrial DNA Fragments inside Nuclear DNA during the Lifetime of an Individual as a Mechanism of Aging
Shamim I. Ahmad in Aging: Exploring a Complex Phenomenon, 2017
The large majority of DNA of the early endosymbiotic α-proteobacteria or cyanobacteria that collaborated to create the eukaryotic animal and plant organelles has been transferred to the nucleus during evolutionary time, leading to the present small genomes of mitochondria and plastids. Interestingly, both plastid and mitochondrial DNA fragments from evolutionary origin present in nDNA are also observed at pericentromeric regions in animals and plants. These fragments suffer vigorous shuffling at the pericentromeric regions, exit them perhaps aided by transposable elements, and are observed dispersed at much lower concentrations across the length of most or all chromosomes depending on the species [33,34]. Thus, the pericentromeric regions seem to be the “entry doors” for the access of mitochondrial (and plastid) DNA fragments into the chromosomes. There is a continuous flux of mtDNA fragments entering and leaving the pericentromeric regions. Perhaps the mtDNA fragments leaving the pericentromeric areas are transferred with the help of TEs to structural genes or their regulatory regions where the mtDNA fragments would modify them.
Neurotransmitters in Marine and Freshwater Algae
Akula Ramakrishna, Victoria V. Roshchina in Neurotransmitters in Plants, 2018
Similarly vexing, algae are not monophyletic, and the term has no taxonomic utility. Most obviously, some authors and most phycology textbooks consider cyanobacteria to be algal and thus clearly different from eukaryotic algae (e.g., see Lee 1999). Even among eukaryotic algae, secondary endosymbiotic events lead to diverse nuclear and mitochondrial genomes associated with the ability to conduct photosynthesis. Representatives are found in the Excavata (e.g., euglenoids), Alveolata (e.g., dinoflagellates), Stramenopila (e.g., kelps and diatoms), and Archaeplastida (i.e., organisms that obtained a plastid via a primary endosymbiosis, including red and green algae as well as land plants), as well as several groups that remain challenging to place in deep eukaryotic phylogenies (Adl et al. 2012) (Figure 3.1). Williams (2014) notes that the Excavata have less genetic similarity to land plants than animals do. The remaining eukaryotic algae (and land plants) are as genetically distinct from each other as animals are from fungi or true amoebae.
Leveraging Genome Sequencing Strategies for Basic and Applied Algal Research, Exemplified by Case Studies
Gokare A. Ravishankar, Ranga Rao Ambati in Handbook of Algal Technologies and Phytochemicals, 2019
C. paradoxa was indeed a great model of study. This species has shown characteristics for retaining ancestral mechanisms of starch biosynthesis, fermentation and translocation of plastid proteins. In this case, the presence of protein-conducting channels in the outer and inner membranes of C. paradoxa plastid casings was a reference to the system of the photosynthetic eukaryotes. The analyses have shown traces of an ancient binding with parasites such as Chlamydiae in the genomes of C. paradoxa and other plants. Apparently, chlamydia-like bacteria seemed to donate genes related to plastid photosynthesis and polysaccharide polymerization to be stored in the cytosol (Chan et al. 2011).
Challenges in the development of egg-independent vaccines for influenza
Published in Expert Review of Vaccines, 2019
Claudia Maria Trombetta, Serena Marchi, Ilaria Manini, Giacomo Lazzeri, Emanuele Montomoli
Plant-based expression systems can be classified as either stable or transient. The former one includes two approaches: the production of recombinant proteins in plants through nuclear genomic integration, and ‘chloroplast transformation’, which is the integration of target genes into the plastid genome. Both have some drawbacks, such as the long time needed to generate stable transformed plants and, often, the low yield of recombinant proteins. Transient systems involve the development of plant virus expression vectors. However, the potential genetic instability of the viral vectors is one of the limitations of the system (Table 1). In order to overcome these limitations, a novel expression system based on a ‘launch vector’ has been developed in which the viral vector is inserted into plants (usually Nicotiana benthamiana) through an Agrobacterium binary plasmid [94,167–171].
Insect-bacterial mosaic produces peptidoglycan in mealybug
Published in Pathogens and Global Health, 2019
Guido Favia
PG is essential to maintain the bacterial cell shape and protect from turgor, it has a fundamental composition, identifiable in all bacteria, although some species-specific variations have been described and they may impact on the pathogenicity of the bacteria [3]. Insects have Peptidoglycan Recognition Proteins (PGRP) that are critical for the detection of pathogen associated molecular patterns and are involved in the activation of anti-bacterial responses [4]. Though the authors do not indicate the functional role of the PG layer, they infer from studies on plastids that the PG takeover from its endosymbiont can represent a critical element in the regulation of the cellular division of the bacteria. Interestingly, in this article the authors refer to a paper by De Vries & Gould (2018) which in moss showed how the knock-out of a PG-related HGT (horizontal gene transfer) on the nuclear genome results in an increased size of chloroplast [5].
Successful production of human epidermal growth factor in tobacco chloroplasts in a biologically active conformation
Published in Growth Factors, 2023
Yunpeng Wang, Jieying Fan, Niaz Ahmad, Wen Xin, Zhengyi Wei, Shaochen Xing
Expression of recombinant proteins by chloroplast transformation shows several advantages: (1), high expression level due to large number of gene copy in a single plant cell; (2), site-specific insertion of transgene into plastid genome by homologous recombination; (3), capable of multigene transformation by using polycistronic strategy; (4), higher biosecurity as most of transgenes in chloroplasts are maternal inheritance. Transformation of the chloroplast genome has shown the expression of recombinant proteins at extraordinary levels (Ahmad et al. 2012; Oey et al. 2009; Ruhlman et al. 2010). For example, 75.60 ± 4.32% TSP of β-glucosidase accumulated in tobacco chloroplasts (Castiglia et al. 2016). Therefore, chloroplast transformation is quite attractive for the cost-effective production of high value targets at large scale (Xing and Liu 2006; Ahmad and Mukhtar 2013; Ahmad et al. 2016). There have been two studies reporting the expression of hEGF in higher plant chloroplasts (Wirth et al. 2006; Morgenfeld et al. 2020). These studies suggested that hEGF were unstable in chloroplasts due to the redox potential and misfolding. The accumulation of native hEGF in the stroma was undetectable, and could only be detected when fused with β-glucuronidase (GUS) in the stroma or fused with transit peptide (Str) and located in the thylakoid lumen. In this study, we report the successful expression of free hEGF with poly-histidine tag in a functionally active form in tobacco chloroplast stroma demonstrating the potential of tobacco chloroplasts for large-scale production of high-value targets of commercial importance.
Related Knowledge Centers
- Chloroplast
- Cyanobacteria
- Eukaryote
- Leucoplast
- Photosynthesis
- Organelle
- Cell
- Endosymbiont
- Chromoplast
- Cyanobiont