Structural motif of the DNA binding domain of γδ-resolvase characterized by affinity cleaving

The DNA binding domain of γδ-resolvase, residues 141-183, is thought to bind DNA by a helix-turn-helix motif based on sequence similarities with other known DNA binding proteins. Incorporation of the DNA cleaving moiety, EDTA Fe, at the NH2 and COOH termini of γδ(141-183) allows the positions of these residues relative to the DNA bases at three resolvase binding sites, each consisting of inverted copies of an imperfectly conserved 9-base pair sequence, to be mapped by high resolution gel electrophoresis. The cleavage data for EDTA-γδ(141-183) reveals that the NH2 terminus of the DNA binding domain of gamma delta-resolvase is bound proximal to the minor groove of DNA near the center of the resolvase binding sites. Cleavage by EDTA Fe attached to a lysine side chain (Asn^(183)→Lys^(183)) at the COOH terminus of γδ(141-183) reveals that the putative recognition helix is in the adjacent major groove on the same face of the helix, oriented toward the center of the inverted repeats

A SQUAMOSA MADS-box gene involved in the regulation of anthocyanin accumulation in bilberry fruits

Anthocyanins are important health promoting phytochemicals that are abundant in many fleshy fruits. Bilberry (Vaccinium myrtillus L.) is one of the best sources of these compounds. Here we report on the expression pattern and functional analysis of a SQUAMOSA (SQUA) class MADS-box transcription factor, VmTDR4, associated with anthocyanin biosynthesis in bilberry. Levels of VmTDR4 expression were spatially and temporally linked with colour development and anthocyanin-related gene expression. Virus induced gene silencing (VIGS) was used to suppress VmTDR4 expression in bilberry resulting in substantial reduction in anthocyanin levels in fully ripe fruits. Chalcone synthase was used a positive control in the VIGS experiments. Additionally, in sectors of fruit tissue in which the expression of the VmTDR4 gene was silenced, the expression of R2R3 MYB family transcription factors related to the biosynthesis of flavonoids were also altered. We conclude that VmTDR4 plays an important role in the accumulation of anthocyanins during normal ripening in bilberry; probably through direct or indirect control of transcription factors belonging to the R2R3 MYB family

Berry phases for composite fermions: effective magnetic field and fractional statistics

The quantum Hall superfluid is presently the only viable candidate for a realization of quasiparticles with fractional Berry phase statistics. For a simple vortex excitation, relevant for a subset of fractional Hall states considered by Laughlin, non-trivial Berry phase statistics were demonstrated many years ago by Arovas, Schrieffer, and Wilczek. The quasiparticles are in general more complicated, described accurately in terms of excited composite fermions. We use the method developed by Kjonsberg, Myrheim and Leinaas to compute the Berry phase for a single composite-fermion quasiparticle, and find that it agrees with the effective magnetic field concept for composite fermions. We then evaluate the "fractional statistics", related to the change in the Berry phase for a closed loop caused by the insertion of another composite-fermion quasiparticle in the interior. Our results support the general validity of fractional statistics in the quantum Hall superfluid, while also giving a quantitative account of corrections to it when the quasiparticle wave functions overlap. Many caveats, both practical and conceptual, are mentioned that will be relevant to an experimental measurement of the fractional statistics. A short report on some parts of this article has appeared previously.Comment: 14 pages, 9 figure

Structural motif of the DNA binding domain of γδ-resolvase characterized by affinity cleaving

The DNA binding domain of γδ-resolvase, residues 141-183, is thought to bind DNA by a helix-turn-helix motif based on sequence similarities with other known DNA binding proteins. Incorporation of the DNA cleaving moiety, EDTA Fe, at the NH2 and COOH termini of γδ(141-183) allows the positions of these residues relative to the DNA bases at three resolvase binding sites, each consisting of inverted copies of an imperfectly conserved 9-base pair sequence, to be mapped by high resolution gel electrophoresis. The cleavage data for EDTA-γδ(141-183) reveals that the NH2 terminus of the DNA binding domain of gamma delta-resolvase is bound proximal to the minor groove of DNA near the center of the resolvase binding sites. Cleavage by EDTA Fe attached to a lysine side chain (Asn^(183)→Lys^(183)) at the COOH terminus of γδ(141-183) reveals that the putative recognition helix is in the adjacent major groove on the same face of the helix, oriented toward the center of the inverted repeats

A SEPALLATA gene is involved in the development and ripening of strawberry (Fragaria xananassa Duch.) fruit, a non-climacteric tissue

Climacteric and non-climacteric fruits have traditionally been viewed as representing two distinct programmes of ripening associated with differential respiration and ethylene hormone effects. In climacteric fruits, such as tomato and banana, the ripening process is marked by increased respiration and is induced and co-ordinated by ethylene, while in non-climacteric fruits, such as strawberry and grape, it is controlled by an ethylene-independent process with little change in respiration rate. The two contrasting mechanisms, however, both lead to texture, colour, and flavour changes that probably reflect some common programmes of regulatory control. It has been shown that a SEPALLATA(SEP)4-like gene is necessary for normal ripening in tomato. It has been demonstrated here that silencing a fruit-related SEP1/2-like (FaMADS9) gene in strawberry leads to the inhibition of normal development and ripening in the petal, achene, and receptacle tissues. In addition, analysis of transcriptome profiles reveals pleiotropic effects of FaMADS9 on fruit development and ripening-related gene expression. It is concluded that SEP genes play a central role in the developmental regulation of ripening in both climacteric and non-climacteric fruits. These findings provide important information to extend the molecular control of ripening in a non-climacteric fruit beyond the limited genetic and cultural options currently available

Synthesis and reactivity of N-allenyl cyanamides

N-Allenyl cyanamides have been accessed via a one-pot deoxycyanamidation–isomerization approach using propargyl alcohol and N-cyano-N-phenyl-p-methylbenzenesulfonamide. The utility of this novel class of allenamide was explored through derivatization, with hydroarylation, hydroamination, and cycloaddition protocols employed to access an array of cyanamide products that would be challenging to access using existing methods

Book Reviews

Current Legal Problems 1956 Edited by G. W. Keeton and G. Schwarzenberger London: Stevens & Sons, 1956. Pp. vii, 275. $5.55 reviewer: David F. Maxwell =================================== Some Problems of Proof under the Anglo-American System of Litigation By Edmund Morris Morgan. New York: Columbia University Press, 1956. Pp. xii, 195.$3.50 reviewer: Charles T. McCormick =================================== Effective Drafting of Leases with Check List and Forms By Milton N. Lieberman Newark: Gann Law Books, 1956. Pp. viii, 974 reviewer: Robert N. Cooks =================================== The Law and One Man Among Many By Arthur E. Sutherland Madison: University of Wisconsin Press, 1956. Pp. ix, 101. $2.50 reviewer: Kenneth B. Hughs =================================== Proxy Contests for Corporate Control By Edward Ross Aranow and Herbert A. Einhorn. New York: Columbia University Press,1957. Pp. xxiii, 577.$15.00 reviewer: Jess Halstead =================================== Gibson\u27s Suits in Chancery By Arthur Crownover, Jr. Charlottesville: The Michie Company, 1955-1956. Vol. I, Pp. xxiii, 909; Vol. II,Pp. xv, 949. $45.00. reviewer: Walter P. Armstrong, Jr. =================================== Laissez Faire and the General-Welfare State: A Study of Conflict in American Thought, 1865-1901. By Sidney Fine Ann Arbor: University of Michigan Press, 1956. Pp. x, 468.$7.50. reviewer: Howard Jay Graha

The Casimir effect as scattering problem

We show that Casimir-force calculations for a finite number of non-overlapping obstacles can be mapped onto quantum-mechanical billiard-type problems which are characterized by the scattering of a fictitious point particle off the very same obstacles. With the help of a modified Krein trace formula the genuine/finite part of the Casimir energy is determined as the energy-weighted integral over the log-determinant of the multi-scattering matrix of the analog billiard problem. The formalism is self-regulating and inherently shows that the Casimir energy is governed by the infrared end of the multi-scattering phase shifts or spectrum of the fluctuating field. The calculation is exact and in principle applicable for any separation(s) between the obstacles. In practice, it is more suited for large- to medium-range separations. We report especially about the Casimir energy of a fluctuating massless scalar field between two spheres or a sphere and a plate under Dirichlet and Neumann boundary conditions. But the formalism can easily be extended to any number of spheres and/or planes in three or arbitrary dimensions, with a variety of boundary conditions or non-overlapping potentials/non-ideal reflectors.Comment: 14 pages, 2 figures, plenary talk at QFEXT07, Leipzig, September 2007, some typos correcte

Aberrantly Expressed Genes in HaCaT Keratinocytes Chronically Exposed to Arsenic Trioxide

Inorganic arsenic is a known environmental toxicant and carcinogen of global public health concern. Arsenic is genotoxic and cytotoxic to human keratinocytes. However, the biological pathways perturbed in keratinocytes by low chronic dose inorganic arsenic are not completely understood. The objective of the investigation was to discover the mechanism of arsenic carcinogenicity in human epidermal keratinocytes. We hypothesize that a combined strategy of DNA microarray, qRT-PCR and gene function annotation will identify aberrantly expressed genes in HaCaT keratinocyte cell line after chronic treatment with arsenic trioxide. Microarray data analysis identified 14 up-regulated genes and 21 down-regulated genes in response to arsenic trioxide. The expression of 4 up-regulated genes and 1 down-regulated gene were confirmed by qRT-PCR. The up-regulated genes were AKR1C3 (Aldo-Keto Reductase family 1, member C3), IGFL1 (Insulin Growth Factor-Like family member 1), IL1R2 (Interleukin 1 Receptor, type 2), and TNFSF18 (Tumor Necrosis Factor [ligand] SuperFamily, member 18) and down-regulated gene was RGS2 (Regulator of G-protein Signaling 2). The observed over expression of TNFSF18 (167 fold) coupled with moderate expression of IGFL1 (3.1 fold), IL1R2 (5.9 fold) and AKR1C3 (9.2 fold) with a decreased RGS2 (2.0 fold) suggests that chronic arsenic exposure could produce sustained levels of TNF with modulation by an IL-1 analogue resulting in chronic immunologic insult. A concomitant decrease in growth inhibiting gene (RGS2) and increase in AKR1C3 may contribute to chronic inflammation leading to metaplasia, which may eventually lead to carcinogenicity in the skin keratinocytes. Also, increased expression of IGFL1 may trigger cancer development and progression in HaCaT keratinocytes