Heterogeneity of ribosome structure, due to variations in ribosomal protein composition, has been shown to be of physiological significance in plants and yeast. Mammalian genomics have demonstrated numerous genes that are paralogous to genes encoding ribosomal proteins. Although the vast majority are considered to be pseudogenes, mRNA expression of a few paralogues, such as human ribosomal protein L39-like/L39-2, has been reported. In the present study, ribosomes from the liver, mammary gland, and testis of rodents were analyzed using a combination of two-dimensional gel electrophoresis under radical-free and highly reducing conditions, and mass spectrometry. This system allowed identification of 78 ribosomal proteins and Rack1 from a single gel. The degree of heterogeneity was far less than that reported for plant and yeast ribosomes, and was in accord with published biochemical and genetic data for mammalian ribosomes. Nevertheless, an uncharacterized paralogue of ribosomal protein L22, ribosomal protein L22-like 1, was identified as a minor ribosomal component. Ribosomal proteins L10-like and L39-like, paralogues of ribosomal proteins L10 and L39, respectively, were found in ribosomes only from the testis. Reverse transcription-polymerase chain reaction yielded supportive evidence for specific expression of L10-like and L39-like in the testis. Newly synthesized L39-like is likely to be transported to the nucleolus, where ribosome biosynthesis occurs, and then incorporated into translating ribosomes in the cytoplasm. Heterogeneity of mammalian testicular ribosomes is structurally non-negligible, and may offer valuable insights into the function of the customized ribosome.
A servo system is generally utilized because it excels at the tracking performance and the disturbance cancellation. However, it sometimes causes an undesirable overshoot in transient responses caused by temporary disturbances such as the impulse disturbance. In such cases, the transient response becomes deteriorated in comparison with the one by the regulator. A method for the improvement of the transient response of the servo system by using controller switching has been proposed. In the method, the controller is switched appropriately between servo system and regulator based on estimated disturbance signal. In addition, the stability of the proposed system is guaranteed by the common solution of Lyapunov inequalities. It is verified that a switching control method improves the transient response which is caused by temporary disturbances such as the impulse disturbance. However, tracking performance sometimes deteriorates when the tracking command and the disturbance are applied to the system at the same time. In the present paper, a novel method for improvement of deterioration in tracking performance by using two degrees of freedom control structure is proposed.By the method, it is possible to improve the tracking response as well as the transient response which is caused by the temporary disturbances. The effectiveness of the proposed method is verified by the two-inertia vibration experimental system by numerical simulations and experiments.
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