Individual kinetochore-fibers locally dissipate force to maintain robust mammalian spindle structure

At cell division, the mammalian kinetochore binds many spindle microtubules that make up the kinetochore-fiber. To segregate chromosomes, the kinetochore-fiber must be dynamic and generate and respond to force. Yet, how it remodels under force remains poorly understood. Kinetochore-fibers cannot be reconstituted in vitro, and exerting controlled forces in vivo remains challenging. Here, we use microneedles to pull on mammalian kinetochore-fibers and probe how sustained force regulates their dynamics and structure. We show that force lengthens kinetochore-fibers by persistently favoring plus-end polymerization, not by increasing polymerization rate. We demonstrate that force suppresses depolymerization at both plus and minus ends, rather than sliding microtubules within the kinetochore-fiber. Finally, we observe that kinetochore-fibers break but do not detach from kinetochores or poles. Together, this work suggests an engineering principle for spindle structural homeostasis: different physical mechanisms of local force dissipation by the k-fiber limit force transmission to preserve robust spindle structure. These findings may inform how other dynamic, force-generating cellular machines achieve mechanical robustness.

Individual kinetochore-fibers locally dissipate force to maintain robust mammalian spindle structure

At cell division, the mammalian kinetochore binds many spindle microtubules that make up the kinetochore-fiber. To segregate chromosomes, the kinetochore-fiber must be dynamic and generate and respond to force. Yet, how it remodels under force remains poorly understood. Kinetochore-fibers cannot be reconstituted in vitro, and exerting controlled forces in vivo remains challenging. Here, we use microneedles to pull on mammalian kinetochore-fibers and probe how sustained force regulates their dynamics and structure. We show that force lengthens kinetochore-fibers by persistently favoring plus-end polymerization, not by increasing polymerization rate. We demonstrate that force suppresses depolymerization at both plus- and minus-ends, rather than sliding microtubules within the kinetochore-fiber. Finally, we observe that kinetochore-fibers break but do not detach from kinetochores or poles. Together, this work suggests an engineering principle for spindle structural homeostasis: different physical mechanisms of local force dissipation by the k-fiber limit force transmission to preserve robust spindle structure. These findings may inform how other dynamic, force-generating cellular machines achieve mechanical robustness.

Structural-technological solutions for the construction of roads on permafrost soils

In this article, the authors briefly reviewed the problem of building roads on permafrost soils, according to the first engineering principle. The probable causes, affecting the thermal regime of the frozen soil at the base of the road, are also considered. In order to stabilize the road structure on permafrost soils, the team of authors of this article proposed 3 structural-technological solutions for the construction of roads, depending on the moisture levels of the upper soil mass, calculated for geotechnical and temperature-humidity conditions typical for the Yamalo-Nenets Autonomous district. The scheme, description and assessment of the effectiveness of each proposed structural-technological solution is given. Efficiency of the assessment is based on a comparison of the numerical modeling results of the water-thermal mode of mound with the proposed structural-technological solutions and ground embankments of roads on permafrost. The results of the numerical modeling of road embankments on permafrost soils are presented. The main conclusions of the research are formulated.

Study and Design Sailboat Type Dinghy

The Objectives of this research are 1) to study the form of Dinghy boat 2) to design a Dinghy boat by using D Ronald K. Kiss Ship’s Iterative Process on Design Spiral, by studying the model’s data of Dinghy sailboats, including related Ideas, theories, and interviews with the yacht racing association of Thailand’s officers. The Purposive Sampling Method as used. After studied the form of the Dinghy boat, the designing process then started by using collected data, through analytical processes with conceptual framework for product design; The Quality Function Deployment, the Theory of Inventive Problem Solving, the Design Spiral which is an iterative Process, and the Reverse Engineering Principle. The experts from both the fields of Industrial Product Design and Sailing Boat, whom concern Dinghy Boat format, were included to evaluate the designing and model constructing process. The statistical methods used were Percentage, Median and Standard Deviation (SD.). The research found that 1) the current type of Dinghy sailboat is still unsafe for novice sailors; It is difficult for practicing, limited on sailor's weight, very difficult to relocate and take care of, it also were built from the expensive materials 2) In designing, the researcher designed the boat's hull by concentrate on its floating center The middle movement, which would have an effect on its floating aspect, which might tilt the boat, to be straight and highly secure. Researcher designed the parts to be able to disassemble and redesign shapes, and use wood as a material for maintenance purpose in accordance with the technical requirements that expected for Dinghy boat, from the Sailing Boat experts under Yacht racing association of Thailand. In the opinions of the honorable experts, the Dinghy Boat type 1 was scored following these factors; Meet the usage demand of the boat (Mean = 3.88, SD. = 0.33) The determination of size and dimension of the boat (Mean = 4.13, SD. = 0.33) The line pattern and shape of the boat ( Mean = 3.88, SD. = 0.33).