Localization and Function of Budding Yeast CENP-A Depends upon Kinetochore Protein Interactions and Is Independent of Canonical Centromere Sequence

SummaryIn many eukaryotes, the centromere is epigenetically specified and not strictly defined by sequence. In contrast, budding yeast has a specific 125 bp sequence required for kinetochore function. Despite the difference in centromere specification, budding yeast and multicellular eukaryotic centromeres contain a highly conserved histone H3 variant, CENP-A. The localization of budding yeast CENP-A, Cse4, requires the centromere DNA binding components, which are not conserved in multicellular eukaryotes. Here, we report that Cse4 localizes and functions at a synthetic kinetochore assembly site that lacks centromere sequence. The outer kinetochore Dam1-DASH and inner kinetochore CBF3 complexes are required for Cse4 localization to that site. Furthermore, the natural kinetochore also requires the outer kinetochore proteins for full Cse4 localization. Our results suggest that Cse4 localization at a functional kinetochore does not require the recognition of a specific DNA sequence by the CBF3 complex; rather, its localization depends on stable interactions among kinetochore proteins

Contributions of phase resetting and interlimb coordination to the adaptive control of hindlimb obstacle avoidance during locomotion in rats: a simulation study.

Obstacle avoidance during locomotion is essential for safe, smooth locomotion. Physiological studies regarding muscle synergy have shown that the combination of a small number of basic patterns produces the large part of muscle activities during locomotion and the addition of another pattern explains muscle activities for obstacle avoidance. Furthermore, central pattern generators in the spinal cord are thought to manage the timing to produce such basic patterns. In the present study, we investigated sensory-motor coordination for obstacle avoidance by the hindlimbs of the rat using a neuromusculoskeletal model. We constructed the musculoskeletal part of the model based on empirical anatomical data of the rat and the nervous system model based on the aforementioned physiological findings of central pattern generators and muscle synergy. To verify the dynamic simulation by the constructed model, we compared the simulation results with kinematic and electromyographic data measured during actual locomotion in rats. In addition, we incorporated sensory regulation models based on physiological evidence of phase resetting and interlimb coordination and examined their functional roles in stepping over an obstacle during locomotion. Our results show that the phase regulation based on interlimb coordination contributes to stepping over a higher obstacle and that based on phase resetting contributes to quick recovery after stepping over the obstacle. These results suggest the importance of sensory regulation in generating successful obstacle avoidance during locomotion

Emission Spectrum of Fundamental Strings: An Algebraic Approach

We formulate a linear difference equation which yields averaged semi-inclusive decay rates for arbitrary, not necessarily large, values of the masses. We show that the rates for decays M \to m+\M' of typical heavy open strings are independent of the masses $M$ and $m$, and compute the ``mass deffect''$M-m-M'$. For closed strings we find decay rates proportional to $M m_{R}^{(1-D)/2}$, where $m_{R}$ is the reduced mass of the decy products. Our method yields exact interaction rates valid for all mass ranges and may provide a fully microscopic basis, not limited to the long string approximation, for the interactions in the Boltzmann equation approach to hot string gases.Comment: 35 pages, 3 figure

A molecular cell biology toolkit for the study of meiosis in the silkworm Bombyx mori

Meiosis is usually described as 4 essential and sequential processes: (1) homolog pairing; (2) synapsis, mediated by the synaptonemal complex; (3) crossing over; and (4) segregation. In this canonical model, the maturation of crossovers into chiasmata plays a vital role in holding homologs together and ensuring their segregation at the first meiotic division. However, Lepidoptera (moths and butterflies) undergo 3 distinct meiotic processes, only one of which is canonical. Lepidoptera males utilize 2 meiotic processes: canonical meiosis that produces nucleated fertile sperm, and a noncanonical meiosis that produces anucleated nonfertile sperm which are nonetheless essential for reproduction. Lepidoptera females, which carry heteromorphic sex chromosomes, undergo a completely achiasmate (lacking crossovers) meiosis, thereby requiring an alternative mechanism to ensure proper homolog segregation. Here, we report that the development of a molecular cell biology toolkit designed to properly analyze features of meiosis, including the synaptonemal complex structure and function, in the silkworm Bombyx mori. In addition to standard homology searches to identify Bombyx orthologs of known synaptonemal complex encoding genes, we developed an ortholog discovery app (Shinyapp) to identify Bombyx orthologs of proteins involved in several meiotic processes. We used this information to clone genes expressed in the testes and then created antibodies against their protein products. We used the antibodies to confirm the localization of these proteins in normal male spermatocytes, as well as using in vitro assays to confirm orthologous interactions. The development of this toolkit will facilitate further study of the unique meiotic processes that characterize meiosis in Lepidoptera.</p

Inter-rater reliability of the AFTD-pitting test among elderly patients in a long-term medical facility

BACKGROUND and AIM: The pitting test has been reported in various methods as a standard for evaluating chronic oedema, but a unified method has not been determined. This makes it difficult to accurately specify the prevalence of oedema. The present study aimed to evaluate inter-rater reliability of the AFTD-pitting test, which included 4 factors: Anatomical locations of oedema; Force required to pit; the amount of Time; and the Definition of oedema. The present study is the first stage of an international epidemiological study of chronic oedema.METHODS: This cross-sectional observational study was performed at a long-term care hospital in Ishikawa Prefecture, Japan. The inter-rater reliability of the pitting test for evaluating oedema using the AFTD-pitting test was tested for 34 locations on the body, with 10 seconds of pitting with a similar force to that of the reference rater and assessed using the modified Fukazawa method. One reference rater and four raters evaluated oedema in five patients. Then, the agreement rate and Cohen-s kappa coefficient were calculated.RESULTS: All protocols were completed by four raters for five bedridden patients. Agreement among the four raters was high, at >0.85, and the kappa coefficient showed almost perfect, moderate, and fair agreement for one (0.81), four (0.51-0.60) rater, respectively.CONCLUSION: The inter-rater reliability of four nurses who applied the AFTD-pitting test was high, and the kappa coefficient showed at least fair agreement. Therefore, the AFTD-pitting test is a useful method to assess whole-body chronic oedema

Melting of tantalum at high pressure determined by angle dispersive x-ray diffraction in a double-sided laser-heated diamond-anvil cell

The high pressure and high temperature phase diagram of Ta has been studied in a laser-heated diamond-anvil cell (DAC) using x-ray diffraction measurements up to 52 GPa and 3800 K. The melting was observed at nine different pressures, being the melting temperature in good agreement with previous laser-heated DAC experiments, but in contradiction with several theoretical calculations and previous piston-cylinder apparatus experiments. A small slope for the melting curve of Ta is estimated (dTm/dP = 24 K/GPa at 1 bar) and a possible explanation for this behaviour is given. Finally, a P-V-T equation of states is obtained, being the temperature dependence of the thermal expansion coefficient and the bulk modulus estimated.Comment: 31 pages, 8 figures, to appear in J.Phys.:Cond.Matte