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Published in Michael Hehenberger, Zhi Xia, Huanming Yang, Our Animal Connection, 2020
Michael Hehenberger, Zhi Xia, Huanming Yang
To understand how knockout mice are created, we need to go back to the role played by DNA in carrying information about the development and function of our bodies throughout life. Our DNA is packaged in chromosomes, which occur in pairs—one inherited from the father and the other from the mother. Exchange of DNA sequences within such chromosome pairs increases genetic variation in the population and occurs by a process called homologous recombination. Homologous recombination is a type of genetic recombination in which nucleotide sequences are exchanged between two similar or identical molecules of DNA. It is used by our cells to accurately repair harmful breaks that occur on both strands of DNA. Homologous recombination also produces new combinations of DNA sequences during meiosis, the process by which eukaryotes make gamete cells, like sperm and egg cells in animals. These new combinations of DNA represent genetic variation in offspring, which in turn enables populations to adapt during the course of evolution. The 2007 Nobel Laureates Mario Capecchi and Oliver Smithies first demonstrated that homologous recombination could be used to specifically modify genes in mammalian cells.
Microbial Biotechnology
Published in Firdos Alam Khan, Biotechnology Fundamentals, 2020
Genetic changes owing to mutations can result in the acquisition of new biological characteristics and thereby allow evolutionary change. However, the evolution of the fittest organism in an environment can be enhanced if transfer of genes between organisms is made possible by genetic recombination. As compared with eukaryotes, where sexual recombination is of an ordered nature, the process is less well-developed in prokaryotes. It does not involve a true fusion of male and female gametes to produce a diploid zygote; instead, there is transfer of only some genes from the donor cell to produce a partial diploid. This is followed by recombination to restore the haploid state. There are three mechanisms by which these DNA fragments can pass from a donor to a recipient cell: transformation, transduction, and conjugation.
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Published in Michael Hehenberger, Zhi Xia, Our Animal Connection, 2019
To understand how knockout mice are created, we need to go back to the role played by DNA in carrying information about the development and function of our bodies throughout life. Our DNA is packaged in chromosomes, which occur in pairs—one inherited from the father and the other from the mother. Exchange of DNA sequences within such chromosome pairs increases genetic variation in the population and occurs by a process called homologous recombination. Homologous recombination is a type of genetic recombination in which nucleotide sequences are exchanged between two similar or identical molecules of DNA. It is used by our cells to accurately repair harmful breaks that occur on both strands of DNA. Homologous recombination also produces new combinations of DNA sequences during meiosis, the process by which eukaryotes make gamete cells, like sperm and egg cells in animals. These new combinations of DNA represent genetic variation in offspring, which in turn enables populations to adapt during the course of evolution. The 2007 Nobel Laureates Mario Capecchi and Oliver Smithies first demonstrated that homologous recombination could be used to specifically modify genes in mammalian cells.
Airborne transmission as an integral environmental dimension of antimicrobial resistance through the “One Health” lens
Published in Critical Reviews in Environmental Science and Technology, 2022
Ling Jin, Jiawen Xie, Tangtian He, Dong Wu, Xiangdong Li
Beyond ARGs, risk-oriented investigations must be directed to antibiotic-resistant bacteria (ARB), particularly those that are able to colonize the human body (vectors), either transiently or as residents, and simultaneously harbor acquired ARGs. The AMR surveillance programs conducted worldwide have identified a few genera or species that fall within the description of widely disseminated AMR vectors (Molton et al., 2013), such as methicillin-resistant Staphylococcus aureas (MRSA), vancomycin-resistant Enterococci (VRE), extended-spectrum beta-lactamase (ESBL), and carbapenemase-producing Enterobacteriaceae, which can be transmitted via inhalation (as illustrated in Figure 2). If such vectors have high fitness in the human body, have acquired resistance to multiple classes of antibiotics, and are able to express specific virulence factors, they can be considered superbugs (i.e., multi-drug resistant pathogens). The threat posed by the vectors may vary depending on their capacity to disseminate ARGs to the host microbiome via free DNA (transformation), plasmids (conjugation), and/or phages (transduction), and to promote genetic recombination through transposons or integrons.
Intensified decontamination of amoxicillin drug wastewater assisted by liquid-phase micro extraction method
Published in Environmental Technology, 2022
Ali Abbasi, Ahmad Rahbar-Kelishami, Zahra Seifollahi, Mohammad Javad Ghasemi
The removal of the drug pollutants from the aqueous environment is essential due to the harmful effects of these materials on the aquatic ecosystem [3,6]. Amoxicillin (AMX) with the chemical formula of C16H19N3O5S is one of the most commonly used antibiotics and it is useful for the treatment of many infectious diseases [7–9]. This medicine is excreted unchanged or in the shape of its metabolites after being consumed by humans and animals [10]. Aquaculture which is regarded as the world’s fastest-growing food industry [11,12] is brought up as ‘genetic reactors’ or ‘hotspots for antimicrobial resistance (AMR) genes’ where genetic recombination and exchange can occur, leading to the expansion of resistant strains of bacteria [13,14]. Some of these medicine employed to remedy fishes are warded off in the water and it is the main reason for pollution from industrial, agricultural, aquaculture, and domestic settings [11,15–17]. A spreading worriment about on the incidence of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in aquatic milieu especially surface water bodies is created [17,18], and it is necessity to plan strategies for increasing water quality. contamination of irrigation water such as lake water and treated wastewater is the reason for the presence of ARG in farm products [19]. Anthropogenic activities may impact the quality of irrigation water [20].
Implications of microbial adaptation for the assessment of environmental persistence of chemicals
Published in Critical Reviews in Environmental Science and Technology, 2019
Baptiste A. J. Poursat, Rob J. M. van Spanning, Pim de Voogt, John R. Parsons
Genetic recombination is an important mechanism employed by bacteria to rapidly adapt to selective pressures such as environmental pollution (Cordero & Polz, 2014; Thavamani et al., 2017; Top & Springael, 2003). In many cases, transfer of genes involved in biodegradation occurred due to plasmid exchange through conjugation events (Janssen et al., 2005; Top et al., 2002; van der Meer & Sentchilo, 2003). Other mobile elements, such as conjugative transposons and genomic islands also seem to play an important role (Top & Springael, 2003; van der Meer & Sentchilo, 2003).