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The canonical example of attenuation used in many introductory genetics textbooks, [1] is ribosome-mediated attenuation of the trp operon. Ribosome-mediated attenuation of the trp operon relies on the fact that, in bacteria, transcription and translation proceed simultaneously. Attenuation involves a provisional stop signal (attenuator ...
For example, the live attenuated influenza vaccine is given nasally and is associated with nasal congestion. [ 25 ] Compared to inactivated vaccines , live-attenuated vaccines are more prone to immunization errors as they must be kept under strict conditions during the cold chain and carefully prepared (e.g., during reconstitution).
For example, one study [12] used serial passage in baboons to create a strain of HIV-2 that is particularly virulent to baboons. Typical strains of HIV-2 only infect baboons slowly. [ 12 ] This specificity makes it challenging for scientists to use HIV-2 in animal models of HIV-1, because the animals in the model will only show symptoms slowly.
Life is a quality that distinguishes matter that has biological processes, such as signaling and self-sustaining processes, from matter that does not. It is defined descriptively by the capacity for homeostasis, organisation, metabolism, growth, adaptation, response to stimuli, and reproduction.
NASA Finds Evidence of Past Martian Microbial Life buradaki - Getty Images In its ancient past, Mars likely contained many of the necessarily ingredients for microbial life to flourish on its surface.
Attenuation theory, also known as Treisman's attenuation model, is a model of selective attention proposed by Anne Treisman, and can be seen as a revision of Donald Broadbent's filter model. Treisman proposed attenuation theory as a means to explain how unattended stimuli sometimes came to be processed in a more rigorous manner than what ...
Nasa may have found evidence of past alien life on Mars. The space agency says that its rover , Perseverance , has found a rock that might once have been host to microbial life, billions of years ago.
The minerals detected included sodium carbonate compounds such as trona (sometimes referred to as “soda ash”) that the scientists said had never been observed in other extraterrestrial samples.