排序方式: 共有82条查询结果,搜索用时 218 毫秒
71.
Hypothesis: For any one time and place a ‘functional signature’ can be derived for a sample of herbaceous vegetation in a way that concisely represents the balance between the different clusters of functional attributes that are present among component species. Methods: We developed a spreadsheet‐based tool for calculating functional signatures within the context of the C‐S‐R system of plant functional types. We used the tool to calculate and compare signatures for specimen British vegetation samples which differed in management regime and location in time. Conclusion: The integrative power of the ‘C‐S‐R signature’ is useful in comparative studies involving widely differing samples. Movements in the signature can be used to indicate degree of resistance, resilience, eutrophication and dereliction. Systems of plant functional types other than C‐S‐R might also be approached in this way. Availability: The tool can be downloaded free of charge from the first author's web pages or from the journal's electronic archive. 相似文献
72.
Background
An important component of sexual selection arises because females obtain viability benefits for their offspring from their mate choice. Females choosing extra-pair fertilization generally favor males with exaggerated secondary sexual characters, and extra-pair paternity increases the variance in male reproductive success. Furthermore, females are assumed to benefit from 'good genes' from extra-pair sires. How additive genetic variance in such viability genes is maintained despite strong directional selection remains an evolutionary enigma. We propose that sexual selection is associated with elevated mutation rates, changing the balance between mutation and selection, thereby increasing variance in fitness and hence the benefits to be obtained from good genes sexual selection. Two hypotheses may account for such elevated mutation: (1) Increased sperm production associated with sperm competition may increase mutation rate. (2) Mutator alleles increase mutation rates that are revealed by the expression of condition-dependent secondary sexual characters used by choosy females during their mate choice. M Petrie has independently developed the idea that mutator alleles may account for the maintenance of genetic variation in viability despite strong directional selection. 相似文献73.
Zn(II) metabolism in prokaryotes 总被引:1,自引:0,他引:1
It is difficult to over-state the importance of Zn(II) in biology. It is a ubiquitous essential metal ion and plays a role in catalysis, protein structure and perhaps as a signal molecule, in organisms from all three kingdoms. Of necessity, organisms have evolved to optimise the intracellular availability of Zn(II) despite the extracellular milieu. To this end, prokaryotes contain a range of Zn(II) import, Zn(II) export and/or binding proteins, some of which utilise either ATP or the chemiosmotic potential to drive the movement of Zn(II) across the cytosolic membrane, together with proteins that facilitate the diffusion of this ion across either the outer or inner membranes of prokaryotes. This review seeks to give an overview of the systems currently classified as altering Zn(II) availability in prokaryotes. 相似文献
74.
Choline kinase has been partially purified from pea seedlings and its properties studied. Using sequence information from soya bean and other choline kinases, we have also isolated a cDNA encoding the enzyme. It encodes a protein of 343 amino acids (calculated molecular mass of 39785 Da), which shows 82% homology with the soya bean choline kinase. The protein has been expressed in Escherichia coli with very good activity and high expression levels. 相似文献
75.
St John JA Braun EL Isberg SR Miles LG Chong AY Gongora J Dalzell P Moran C Bed'hom B Abzhanov A Burgess SC Cooksey AM Castoe TA Crawford NG Densmore LD Drew JC Edwards SV Faircloth BC Fujita MK Greenwold MJ Hoffmann FG Howard JM Iguchi T Janes DE Khan SY Kohno S de Koning AJ Lance SL McCarthy FM McCormack JE Merchant ME Peterson DG Pollock DD Pourmand N Raney BJ Roessler KA Sanford JR Sawyer RH Schmidt CJ Triplett EW Tuberville TD Venegas-Anaya M Howard JT Jarvis ED Guillette LJ Glenn TC 《Genome biology》2012,13(1):415-12
The International Crocodilian Genomes Working Group (ICGWG) will sequence and assemble the American alligator (Alligator mississippiensis), saltwater crocodile (Crocodylus porosus) and Indian gharial (Gavialis gangeticus) genomes. The status of these projects and our planned analyses are described. 相似文献
76.
Amalia Kallergi Enrique AsinGarcia Vitor AP Martins dos Santos Laurens Landeweerd 《EMBO reports》2021,22(1)
Biosafety is a major challenge for developing for synthetic organisms. An early focus on application and their context could assist with the design of appropriate genetic safeguards. Subject Categories: Synthetic Biology & Biotechnology, S&S: Economics & BusinessOne of the goals of synthetic biology is the development of robust chassis cells for their application in medicine, agriculture, and the food, chemical and environmental industries. These cells can be streamlined by removing undesirable features and can be augmented with desirable functionalities to design an optimized organism. In a direct analogy with a car chassis, they provide the frame for different modules or “plug‐in” regulatory networks, metabolic pathways, or safety elements. In an effort to ensure a safe microbial chassis upfront, safety measures are implemented as genetic safeguards to limit risks such as unwanted cellular proliferation or horizontal gene transfer. Examples of this technology include complex genetic circuits, sophisticated metabolic dependencies (auxotrophies), and altered genomes (Schmidt & de Lorenzo, 2016; Asin‐Garcia et al, 2020). Much like seat belts or airbags in cars, these built‐in measures increase the safety of the chassis and of any organisms derived from it. Indeed, when it comes to safety, synthetic biology can still learn from a century‐old technology such as cars about the significance of context for the development of biosafety technologies.Every car today has seat belts installed by default. Yet, seat belts were not always a standard component; in fact, they were not even designed for cars to begin with. The original 2‐point belts were first used in aviation and only slowly introduced for motorized vehicles. Only after some redesign, the now‐common 3‐point car seat belts would become the life‐saving equipment that they are today. A proper understanding of the context of their application was therefore one of the crucial factors for their success and wide adoption. Context matters: It provides meaning for and defines what a technological application is best suited for. What was true for seat belts may be also true for biosafety technologies such as genetic safeguards.
… when it comes to safety, synthetic biology can still learn from a century‐old technology such as cars about the significance of context for the development of biosafety technologies.Society has a much higher awareness of technology’s risks compared to the early days of cars. Society today requires that technological risks are anticipated and assessed before an innovation or its applications are widely deployed. In addition, society increasingly demands that research and innovation take into account societal needs and values. This has led to, among others, the Responsible Research and Innovation (RRI; von Schomberg, 2013) concept that has become prominent in European science policy. In a nutshell, RRI requires that innovative products and processes align with societal needs, expectations, and values in consultation with stakeholders. RRI and similar frameworks suggest that synthetic biology must anticipate and respond not only to risks, but also to societal views that frame its evaluation and risk assessment. 相似文献
77.
78.
79.
AAM Coelho-Castelo AP Trombone RS Rosada RR Santos Jr VLD Bonato A Sartori CL Silva 《Genetic vaccines and therapy》2006,4(1):1-10
In order to assess a new strategy of DNA vaccine for a more complete understanding of its action in immune response, it is important to determine the in vivo biodistribution fate and antigen expression. In previous studies, our group focused on the prophylactic and therapeutic use of a plasmid DNA encoding the Mycobacterium leprae 65-kDa heat shock protein (Hsp65) and achieved an efficient immune response induction as well as protection against virulent M. tuberculosis challenge. In the present study, we examined in vivo tissue distribution of naked DNA-Hsp65 vaccine, the Hsp65 message, genome integration and methylation status of plasmid DNA. The DNA-Hsp65 was detectable in several tissue types, indicating that DNA-Hsp65 disseminates widely throughout the body. The biodistribution was dose-dependent. In contrast, RT-PCR detected the Hsp65 message for at least 15 days in muscle or liver tissue from immunized mice. We also analyzed the methylation status and integration of the injected plasmid DNA into the host cellular genome. The bacterial methylation pattern persisted for at least 6 months, indicating that the plasmid DNA-Hsp65 does not replicate in mammalian tissue, and Southern blot analysis showed that plasmid DNA was not integrated. These results have important implications for the use of DNA-Hsp65 vaccine in a clinical setting and open new perspectives for DNA vaccines and new considerations about the inoculation site and delivery system. 相似文献
80.
Cristina Ribeiro Roberto C Togawa Izabella AP Neshich Ivan Mazoni Adauto L Mancini Raquel C de Melo Minardi Carlos H da Silveira José G Jardine Marcelo M Santoro Goran Neshich 《BMC structural biology》2010,10(1):36