Understanding that evolution progresses through generation of DNA variants followed by selection is a key learning outcome for biology students. We designed an integrated and innovative undergraduate laboratory exercise using Saccharomyces cerevisiae to demonstrate these principles. Students perform in vitro experimental evolution by repeatedly propagating large or small yeast colonies on a weekly basis. Small-colony variants known as petites arise by mutations that disrupt aerobic respiration. To demonstrate the effects of increased mutation rates, half of the selection lines are exposed to ultraviolet irradiation. To understand how the petite phenotype arises, polymerase chain reaction (PCR) is performed to examine mitochondrial DNA, while biochemical assays are used to assess the ability of petites to undergo aerobic respiration. This exercise demonstrates evolution by artificial selection over a suitably short timeframe and links the results to a critical biochemical process: the role of mitochondria in aerobic respiration and ATP production. By implementing these experiments, we successfully demonstrated that the frequencies of petite mutants in evolved populations varied according to the selection pressure we applied, and that petite mutants carried deletions in mitochondrial DNA as anticipated. Through an integrated learning context, this practical exercise promotes fundamental understanding of evolutionary processes and fosters critical thinking skills.
Conduit connectors are widely used in the manufacturing of aviation equipment such as aircraft engines and aircraft assemblies. The surface roughness of conduit connector is a key quality characteristic to ensure the sealing connection of pipeline systems. Small deviations in the surface quality of conduits can lead to significant quality issues in aircraft, so high-precision measurement of micro roughness of conduit connector surfaces is of great significance for controlling aircraft quality and optimizing support manufacturing processes. Compared with contact measurement methods, optical measurement methods take an irreplaceable position in micro-nano scale roughness measurement which have many advantages such as non-destructive, high-precision and high-speed. An optical measurement method for surface roughness of aircraft conduit connector based on a triangular structured illumination system is proposed in this article, which combines high-precision fringe phase analysis algorithm and accurate height mapping algorithm to realize morphological restoration and the calculation of the roughness of the tested area. Relational experiment is carried out to verify the feasibility of the proposed method.
The non specific humoral and cellular immunomodulatory effects of dietary vitamin C(Vc) on grouper Epinephelus awoara were studied.Grouper were provided with frozen diet fish(trash fish)supplemented with different doses of vitamin C(0,500,1?000,1?500,2?000?mg·kg -1 )continuously for 20 weeks.It was found that the total blood leucocyte number and the composition proportion of different leucocytes including lymphocyte,neutrophil and monocyte were unaffected by vitamin C.The activity of classical haemolysis of serum complement to sheep red blood cells(SRBC)significantly increased with the increase of vitamin C( p 0.01).However,no difference was seen in the bactericidal complement activity of serum among fish treated with dietary vitamin C.The non specific cellular defence mechanisms were examined.Blood leucocyte phagocytosis to Staphylococci aureus and phagocytic activity of adherent head kidney cells were unaffected by dietary vitamin C.
Horizontal gene transfer between different domains of life is increasingly being recognized as an important evolutionary driver, with the potential to increase the pace of biochemical innovation and environmental adaptation. However, the mechanisms underlying the recruitment of exogenous genes from foreign domains are mostly unknown. Integrons are a family of genetic elements that facilitate this process within Bacteria. However, they have not been reported outside Bacteria, and thus their potential role in cross-domain gene transfer has not been investigated. Here, we discover that integrons are also present in 75 archaeal metagenome-assembled genomes from nine phyla, and are particularly enriched among Asgard archaea. Furthermore, we provide experimental evidence that integrons can facilitate the recruitment of archaeal genes by bacteria. Our findings establish a previously unknown mechanism of cross-domain gene transfer whereby bacteria can incorporate archaeal genes from their surrounding environment via integron activity. These findings have important implications for prokaryotic ecology and evolution.
Pyroptosis is a new form of programmed cell death generated by some inflammasomes, piloting the cleavage of gasdermin (GSDM) and stimulation of dormant cytokines like IL-18 and IL-1β; these reactions are narrowly linked to certain diseases like diabetic nephropathy and atherosclerosis. Doxorubicin, a typical anthracycline, and famous anticancer drug has emerged as a prominent medication in several cancer chemotherapies, although its application is accompanied with expending of dose-dependent, increasing, irreversible and continuing cardiotoxic side effects. However, the exact path that links the induced pyroptosis to the mechanism by which Doxorubicin (DOX) acts against breast cancer cells is still puzzling. The present study seeks to elucidate the potential link between DOX-induced cell death and pyroptosis in two human breast cancer cell lines (MDA-MB-231 and T47D). We proved that treatment with DOX reduced the cell viability in a dose-dependent way and induced pyroptosis morphology in MDA-MB-231 and T47D cells. Also, protein expression analyses revealed GSDME as a key regulator in DOX-induced pyroptosis and highlighted the related role of Caspase-3 activation. Furthermore, DOX treatments induced intracellular accumulation of ROS, stimulated the phosphorylation of JNK, and Caspase-3 activation, subsequently. In conclusion, the study suggests that GSDME triggered DOX-induced pyroptosis in the caspase-3 dependent reactions through the ROS/JNK signalling pathway. Additionally, it showed that the DOX-induced cardiotoxicity and pyroptosis in breast cancer cells can be minimized by reducing the protein level of GSDME; thus, these outcomes provide a new research target and implications for the anticancer investigations and therapeutic applications.
Societal Impact Statement Plants and bacteria interact in complex ways that are crucial to the health and productivity of native vegetation and croplands. While the range of characterised plant‐beneficial bacterial traits continues to grow, key questions remain regarding the distribution and mobility of genes associated with these traits. This work explores the diversity of mobile genetic elements carried by bacteria associated with plant root surfaces, assessing their capacity to help shape plant–bacterial interactions. The significance of this work lies in the potential to contribute to new strategies for enhancing plant health, promoting sustainable agriculture and managing plant diseases in an era when we must respond to environmental change. Summary Integrons are gene capture and expression systems that contribute to bacterial adaptation. Integron research has mainly focused on the role that these elements play in spreading antimicrobial resistance. However, their contribution to niche adaptation is potentially much broader because integrons can sample the vast repertoire of diverse functions encoded by integron gene cassettes. Integrons and gene cassettes have been identified in many bacterial lineages residing in soil and water across varied ecosystems, but there has been little investigation of integrons in plant‐associated bacteria. Bacteria and plants have complex, dynamic relationships that influence plant health and productivity. To investigate whether integrons contribute to adaptative processes in plant microbiomes, we examined gene cassette and microbial taxonomic profiles in rhizoplanes of four important crop species grown under controlled glasshouse conditions. We identified 38,546 unique gene cassettes, including elements carrying genes associated with antibiotic resistance, type II toxin–antitoxin systems and genes with putative functions associated with plant growth promotion, along with a larger set encoding genes of unknown functions. Rhizoplane microbiomes of different plant species showed more similarity in their community composition profiles than in their gene cassette profiles, with complex and distinct suites of gene cassettes associated with each plant species, suggesting that gene cassettes might have a role in specific plant–bacterial interactions. We show that rhizoplane microbiomes carry diverse integron gene cassettes that could play a role in establishing and maintaining rhizoplane communities.
ZHU Shun\|shui's theory of meticulous scholarship stressed on teaching morals, learning and practising. Teaching morals means as a teacher to be a model of scholarship. Learning means paying more attention to the methods of reading and then well\|read. Practising means to test the result of learning through practice.
Integrons were first identified because of their central role in assembling and disseminating antibiotic resistance genes in commensal and pathogenic bacteria. However, these clinically relevant integrons represent only a small proportion of integron diversity. Integrons are now known to be ancient genetic elements that are hotspots for genomic diversity, helping to generate adaptive phenotypes. This perspective examines the diversity, functions, and activities of integrons within both natural and clinical environments. We show how the fundamental properties of integrons exquisitely pre-adapted them to respond to the selection pressures imposed by the human use of antimicrobial compounds. We then follow the extraordinary increase in abundance of one class of integrons (class 1) that has resulted from its acquisition by multiple mobile genetic elements, and subsequent colonisation of diverse bacterial species, and a wide range of animal hosts. Consequently, this class of integrons has become a significant pollutant in its own right, to the extent that it can now be detected in most ecosystems. As human activities continue to drive environmental instability, integrons will likely continue to play key roles in bacterial adaptation in both natural and clinical settings. Understanding the ecological and evolutionary dynamics of integrons can help us predict and shape these outcomes that have direct relevance to human and ecosystem health.
Probiotics such as Lactobacillus and Bifidobacterium have been successfully used to promote growth and prevent diseases. Previous reports have demonstrated that Bacillus subtilis (B. subtilis) was a potential probiotic for animals. In this research, 180 B. subtilis were isolated from the soil, identified and investigated in vitro. Furthermore, five B. subtilis were selected and mixed to investigate their effect on growth performance, immune response, intestine microbiota and disease resistance in rabbits. Rabbits with a diet of 106 CFU g-1 mixed B. subtilis exhibited the best growth performance, and higher serum IgG and IgA than controls (P < 0.05). Moreover, dairy with B. subtilis can promote the balance of intestinal flora. The major pro-inflammatory factor and β-defensin were up-regulated compared with the controls. After 7 weeks of feeding, the survival rate of the rabbits fed with B. subtilis was significantly higher than those in the control groups post-infected with Escherichia coli. At the same time, this study detected higher expression of β-defensin and reduced bacteria contents of the heart and cecal contents from the diet mixed with B. subtilis compared with the control groups. In conclusion, dietary supplementation with B. subtilis for rabbits could improve growth performance, serum immunoglobulin, intestinal homeostasis and immune organ index, and enhance innate immune response as well as disease resistance. These findings showed that the induction of β-defensin by B. subtilis might be an interesting new therapeutic strategy to strengthen innate defence mechanisms.
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