Dictyostelium Myosin-IE Is a Fast Molecular Motor Involved in Phagocytosis

Class I myosins are single-headed motor proteins, implicated in various motile processes including organelle translocation, ion-channel gating, and cytoskeleton reorganization. Here we describe the cellular localization of myosin-IE and its role in the phagocytic uptake of solid particles and cells. A complete analysis of the kinetic and motor properties of Dictyostelium discoideum myosin-IE was achieved by the use of motor domain constructs with artificial lever arms. Class I myosins belonging to subclass IC like myosin-IE are thought to be tuned for tension maintenance or stress sensing. In contrast to this prediction, our results show myosin-IE to be a fast motor. Myosin-IE motor activity is regulated by myosin heavy chain phosphorylation, which increases the coupling efficiency between the actin and nucleotide binding sites tenfold and the motile activity more than fivefold. Changes in the level of free Mg(2+) ions, which are within the physiological range, are shown to modulate the motor activity of myosin-IE by inhibiting the release of adenosine diphosphate

Optical Study of the Stripe-Ordered State

The effects of the stripe order on the optical spectra of La-based cuprates are reviewed. The main effect on the high Tc superconducting cuprates is to rapidly reduce the Josephson plasma frequency in the c-axis spectrum as a consequence of weakening of the Josephson coupling between CuO2 layers. This points toward a two dimensional (2D) superconductivity in the stripe phase, although it is difficult to realize a 2D superconductivity in real materials. We also discuss the experimental results suggesting the presence of stripe effect in other cuprates even if they do not show the static stripe phase. Compared to the c-axis spectra, the in-plane spectra are not so dramatically affected by the stripe order, showing a weak gap-like feature and reducing the condensate spectral weight.Comment: in press, Physica C(2012

初年次基礎教育科目における予習課題および復習、Google Classroom を使用した小テストの学生の実施状況および学生からの評価

　初年次基礎教育科目「疾病治療概論」における予習課題、復習、Google Classroom を使用した小テストに対する評価を明らかにすることを目的として、A 大学の1 年生を対象にアンケート調査を行った。72 名より回答があり（回収率97.3％）、予習課題は授業内容の理解に役立ったかの質問には、“そう思う”が40.3％、“ややそう思う”が52.8％であった。復習は授業内容の理解に役立ったかの質問には、“そう思う”が61.4％、“ややそう思う”が38.6％であった。小テストは授業内容の理解に役立ったかの質問には、“そう思う”が56.3％、“ややそう思う”42.3％であり、今後の授業でもGoogle Classroom を使った小テストを希望する学生は65.3％であった。　web 経由でスマートフォンから手軽に解答できるツールは、授業内容の理解を高めることに有効であり、新型コロナウイルス感染症が流行している状況においても学習の継続に貢献できる可能性が示された

Complete coding sequences of cDNAs of four variants of rabbit skeletal muscle troponin T

Four variants of troponin T (TnT) cDNAs have been isolated and sequenced. These cDNAs have been derived from rabbit skeletal muscle, the most widely studied source of troponin, of a 11-day-old animal. One variant (TnT-1) contains the complete coding sequence, while in three variants the coding sequences are truncated at the 5′ termini. The previously published amino acid sequence differs from the present cDNA-derived sequences at three locations. At least two, possibly all, of them are probably accounted for by errors in peptide sequencing. The present results are consistent with the two types of alternative splicing of TnT genes, both being first reported on the rat gene. (1) Highly variable sequences in the amino-terminal region are accounted for by the alternative splicing of exons 4–8 in an interchangeable but not mutually exclusive manner. (2) In the carboxyl-terminal region, the alternative splicing of two exons 17 (β-type) or 16 (α-type) in mutually exclusive manner is consistent with the difference between all the four cDNAs, which express exon 17, and the previously published peptide sequence (derived from the adult muscle) in which exon 16 is present. This variation also corresponds to the finding in chicken skeletal muscle that the choice of exon 16 or 17 may be dependent on developmental stages. Finally, a sequence is observed corresponding to an extra exon or exons between exons 5 and 6. This sequence is shorter than that of the chicken skeletal muscle gene and is not detected in the rat skeletal muscle gene

A Dirofilaria immitis Polyprotein Up-Regulates Nitric Oxide Production

We investigated the effect of recombinant Dirofilaria immitis polyprotein (rDiAg) on nitric oxide (NO) production by peritoneal macrophages. rDiAg induced NO production by macrophages from wild-type and lipopolysaccharide-hyporesponsive C3H/HeJ, but not CD40(−/−), mice. These results suggest that CD40 is involved in rDiAg-driven NO production by murine macrophages

Molecular engineering of a backwards−moving myosin motor

All members of the diverse myosin superfamily have a highly conserved globular motor domain that contains the actin− and nucleotide−binding sites and produces force and movement1, 2. The light−chain−binding domain connects the motor domain to a variety of functionally specialized tail domains and amplifies small structural changes in the motor domain through rotation of a lever arm3, 4. Myosins move on polarized actin filaments either forwards to the barbed (+ ) or backwards to the pointed (− ) end5, 6. Here, we describe the engineering of an artificial backwards−moving myosin from three pre−existing molecular building blocks. These blocks are: a forward−moving class I myosin motor domain, a directional inverter formed by a four−helix bundle segment of human guanylate−binding protein−1 and an artificial lever arm formed by two −actinin repeats. Our results prove that reverse−direction movement of myosins can be achieved simply by rotating the direction of the lever arm 180°. Most myosins move towards the barbed (+ ) end of actin filaments, but recent studies have established that at least one member of the family, myosin VI, moves towards the pointed (− ) end5. The structural basis for reverse−direction movement has not been established. Two mechanisms for achieving reversal of myosin motility on the inherently polar actin filament have been suggested. On the basis of direct functional assays, electron microscopy and sequence analysis, Sweeney and co−workers proposed a model whereby reversal is achieved by rotating the lever arm in the opposite direction to conventional myosin lever arm movement5 (Fig. 1). Ikebe and co−workers, however, measured the motile properties of chimaeric constructs and proposed that the core of the motor domain is the sole determinant of directionality6

Various Types of Dirofilaria immitis Polyproteins Selectively Induce a Th2-Type Immune Response

Dirofilaria immitis polyproteins (DiAgs) are found as 15-kDa monomeric and 30-kDa dimeric forms in exceretory-secretory products of the adult worm. We evaluated the ability of various types of recombinant DiAg (rDiAg; V1 and V2 as monomers and V1V2, V2V1, V1V1, and V2V2 as dimers) to influence Th1/Th2 immune responses. V1-, V1Vx- and V2-, V2Vx-driven nonspecific immunoglobulin E (IgE) production peaked at 21 and 14 days after administration, respectively. Dimer-induced IgE response was an interesting biphasic pattern with the second peaks on days 35 (V2Vx) or 42 (V1Vx). Absolute amounts of nonspecific IgE production induced with monomers were larger than those observed with dimers at the first peak. The magnitude of cell expansion and interleukin-10 (IL-10) production in mesenteric lymph node (MLN) B-cell induced with rDiAgs was linked to the levels of the first IgE peak in vivo and IgE produced by rDiAg plus IL-4-stimulated B cells in vitro. All rDiAgs failed to augment IgG2c production. V2 and V2Vx elicited IL-4 production by MLN cells more rapidly than V1 and V1Vx. The inhibitory effect of rDiAg on gamma interferon (IFN-γ) production was stronger in monomers than in dimers. Neutralization of IL-10 restored IFN-γ production, whereas the expression of IL-4 and IgE was partly prevented by depletion of IL-10. These results indicate that monomer rather than dimer is an efficient form of DiAg and suggest that the difference of IgE-inducing capacity among these DiAgs is closely associated with the pattern of both B-cell activation and IL-4 production