Мutants of inflorescence development in alfalfa (Medicago sativa L.)

Alfalfa (Medicago sativa L., Medicago varia Mart., Medicago falcata L.) is a perennial leguminous plant  well-known as the queen of forages  cultivated  all over the world. The general  biology and morphology of the plant  has been described in detail. The typical inflorescence of the plant is raceme. Due to the multistep inbreeding process  in this cross-pollinated species, different mutant forms have been  found  in inbred  progenies. They include long racemes, panicle-like racemes  (with fertile and sterile flowers), complicated branched racemes,  and fasciated  inflorescences. The fasciation trait was discovered first in long racemes  and then it was introduced into every mutant inflorescence type by hand  pollination. By means  of pair hybridization,  transitional  forms of some mutants were isolated and the new mutant forms combined two or three  mutant genes.  New gene  names  are proposed for new duplex  and triplex mutant types: lpfas, pi1lpfas, brilpfas. Medicago truncatula is a conventional model species for legume  genome research. M. truncatula and alfalfa share highly conserved nucleotide sequences and exhibit nearly perfect  synteny between the two genomes. The knowledge about inflorescence development in model M. truncatula plants adds to understanding the genetic nature of mutant inflorescence development in alfalfa; therefore, we compiled the information on the genetic regulation of inflorescence development in M. truncatula. The M. truncatula mutant mtpim has a complicated inflorescence structure resembling panicle-like inflorescence in alfalfa. Presently, it is known that the inflorescence architecture in M. truncatula is controlled by spatiotemporal expression  of MtTFL1, MtFULc, MtAP1, and SGL1 through reciprocal repression.  Some mutants isolated in M. truncatula resemble alfalfa mutants in phenotype. The mutant generated by retrotransposon insertion mutagenesis and named sgl1-1 has a cauliflower-like phenotype looking just like the cauliflower mutant in alfalfa. New data concerning genes regulating inflorescence development in model legumes approach us to understanding the phenomenon of inflorescence mutations in alfalfa. The information of inflorescence mutants in nonmodel crops may augment our knowledge of plant development and help crop improvement

THE ROLE OF N. I. VAVILOV AND VIR’S SCIENTISTS IN DESERT RECLAMATION

The article is devoted to the origins of the fight against desert expansion in Russia and former Soviet Republics of Central Asia and Kazakhstan, and N. I. Vavilov’s plans to solve the complex problems of desert and semi-desert reclamation in the areas of the USSR; afforestation, melioration and climatic studies; problems of southern industrial crops; formation of sustainable forage crop cultivation for livestock, and establishment of oases. The research on this topic was conducted by the Repetek Sand Desert Station (run by VIR from 1925 to 1941) with a supporting site in the Kara-Bogaz-Gol, the Aral Experimental Station (organized in 1933), the Turkmen Research Station of VIR in Kara-Kala (established in 1927), the Azerbaij ani branch VIR on the Apsheron Peninsula (organized in 1926). Investigations of the desert were started by the Repetek Sand Desert Station, the only one in the world involved in the stationary study of sands. Its staff examined the typology of sands in the southeastern Karakum, the nature of their movement, conducted edaphic, botanical and hydrological studies in the area of construction of the Karakum Channel. They were the first in the world to suggest using phytomelioration by psammophytes of moving sands, conducted successful experiments in the introduction of black saxaul, calligonum and sandy acacia into cultivation and discovered the wet condensation subsurface horizon creating reserves of moisture in the sand dunes. In 1932, when the Bureau of Deserts was founded, its coordination plan served as the foundation for the deployment of investigations throughout sands of Russia and Central Asian Republics. Huge work was carried out on integrated geobotanical, geological, hydrological studies of soil and vegetation of deserts and semi-deserts (Astrakhan, Pridon, Terek-Kuma, Uilskie, Naryn sands, the Karakum, Kyzylkum, Betpakdala, Mangyshlak, Aral Sea region, Muyunkum, etc.), as well as evaluation of their suitability for rainfed and irrigated agriculture, productivity of natural pastures, hayfields, saxaul forests. Valuable food, fodder and technical plants were studied. Scientists of the Aral Experimental Station received the State Prize for the development of rainfed, irrigated and trench cultivation of cereals, forages, vegetables, fruits and ornamental crops and for making oases in a desert environment. They selected, bred, propagated and introduced into the agriculture of Kazakhstan more than 40 varieties of different agricultural crops. Development and implementation of the technology for consolidation and afforestation of sands in the southeast and east of the European part of the country and development of the first cultivar of saxaul Priaralskiy 1 also won the State Prize. After the transfer of the Aral Experimental Station under the jurisdiction of the Republic of Kazakhstan, expeditions collecting desert plant genetic resources, their study and building up a collection of worldwide genetic resources of desert crops were continued. At the present level, to assess salt tolerance of alfalfa transcriptome analysis was applied. Employees of the Department of Perennial Forage Crop Genetic Resources of VIR took part in the mapping of arid areas and sustainable fodder plant distribution for the Internet publication “Interactive Agricultural Ecological Atlas of Russia and Neighboring Countries Economic Plants and their Diseases, Pests and Weeds.” On the basis of the world collection of desert agricultural cultivars breeders of the Aral Experimental Station, as well as the institutions of the country and some foreign countries developed numerous varieties

PERENNIAL AND ANNUAL DROUGHT- AND SALT-RESISTANT FORAGE PLANTS IN THE VAVILOV COLLECTION

The 100-year history of building up the VIR collection of genetic resources of drought- and salt-resistant perennial and annual forage crops and its current status are described. Numerous expeditions were conducted to collect valuable germplasm material. The collections of a number of drought- and salt-resistant forage plants were established and studied. Breeders from VIR, its network and other breeding centers developed drought-resistant and salt-resistance varieties on the basis of the Vavilov collection. Theoretical and practical research on the physiology of desert plants was further developed. Currently salt tolerance of forage crops is assessed using molecular methods

Theory of Photoluminescence of the ν=1\nu=1 Quantum Hall State: Excitons, Spin-Waves and Spin-Textures

We study the theory of intrinsic photoluminescence of two-dimensional electron systems in the vicinity of the $\nu=1$ quantum Hall state. We focus predominantly on the recombination of a band of initial ``excitonic states'' that are the low-lying energy states of our model at $\nu=1$. It is shown that the recombination of excitonic states can account for recent observations of the polarization-resolved spectra of a high-mobility GaAs quantum well. The asymmetric broadening of the spectral line in the $\sigma_-$ polarization is explained to be the result of the ``shake-up'' of spin-waves upon radiative recombination of excitonic states. We derive line shapes for the recombination of excitonic states in the presence of long-range disorder that compare favourably with the experimental observations. We also discuss the stabilities and recombination spectra of other (``charged'') initial states of our model. An additional high-energy line observed in experiment is shown to be consistent with the recombination of a positively-charged state. The recombination spectrum of a negatively-charged initial state, predicted by our model but not observed in the present experiments, is shown to provide a direct measure of the formation energy of the smallest ``charged spin-texture'' of the $\nu=1$ state.Comment: 23 pages, 7 postscript figures included. Revtex with epsf.tex and multicol.sty. The revised version contains slightly improved numerical results and a few additional discussions of the result

On the universal AC optical background in graphene

The latest experiments have confirmed the theoretically expected universal value $\pi e^2/2h$ of the ac conductivity of graphene and have revealed departures of the quasiparticle dynamics from predictions for the Dirac fermions in idealized graphene. We present analytical expressions for the ac conductivity in graphene which allow one to study how it is affected by interactions, temperature, external magnetic field and the opening of a gap in the quasiparticle spectrum. We show that the ac conductivity of graphene does not necessarily give a metrologically accurate value of the von Klitzing constant $h/e^2$, because it is depleted by the electron-phonon interaction. In a weak magnetic field the ac conductivity oscillates around the universal value and the Drude peak evolves into a peak at the cyclotron frequency.Comment: 18 pages, 4 figures; v2: to match New J. Phys. (Focus on Graphene issue

Compromised Hippocampal Neuroplasticity in the Interferon-α and Toll-like Receptor-3 Activation-Induced Mouse Depression Model.

Disrupted neuronal plasticity due to subtle inflammation is considered to play a fundamental role in the pathogenesis of major depressive disorder. Interferon-α (IFN-α) potentiates immune responses against viral pathogens that induce toll-like receptor-3 (TLR3) activation but evokes severe major depressive disorder in humans by mechanisms that remain insufficiently described. By using a previously established mouse model of depression induced by combined delivery of IFN-α and polyinosinic:polycytidylic acid (poly(I:C)), a TLR3 agonist, we provide evidence that IFN-α and poly(I:C) reduce apical dendritic spine density in the hippocampal CA1 area ex vivo via mechanisms involving decreased TrkB signaling. In vitro, IFN-α and poly(I:C) treatments required neuronal activity to reduce dendritic spine density and TrkB signaling. The levels of presynaptic protein vesicular glutamate transporter (VGLUT)-1 and postsynaptic protein postsynaptic density-95 (PSD95) were specifically decreased, whereas the expression of both synaptic and extrasynaptic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor 1 (AMPAR1) was increased by IFN-α and poly(I:C) delivery. Patch clamp recordings in primary hippocampal neurons revealed that morphological changes at the synapse induced by IFN-α and poly(I:C) costimulation were accompanied by an increased action potential threshold and action potential frequency, indicative of impaired neuronal excitability. Taken together, IFN-α and poly(I:C) delivery leads to structural and functional alterations at the synapse indicating that compromised neuroplasticity may play an integral role in the pathogenesis of immune response-induced depression

Energy spectra of fractional quantum Hall systems in the presence of a valence hole

The energy spectrum of a two-dimensional electron gas (2DEG) in the fractional quantum Hall regime interacting with an optically injected valence band hole is studied as a function of the filling factor $\nu$ and the separation $d$ between the electron and hole layers. The response of the 2DEG to the hole changes abruptly at $d$ of the order of the magnetic length $\lambda$. At $d<\lambda$, the hole binds electrons to form neutral ($X$) or charged ($X^-$) excitons, and the photoluminescence (PL) spectrum probes the lifetimes and binding energies of these states rather than the original correlations of the 2DEG. The ``dressed exciton'' picture (in which the interaction between an exciton and the 2DEG was proposed to merely enhance the exciton mass) is questioned. Instead, the low energy states are explained in terms of Laughlin correlations between the constituent fermions (electrons and $X^-$'s) and the formation of two-component incompressible fluid states in the electron--hole plasma. At $d>2\lambda$, the hole binds up to two Laughlin quasielectrons (QE) of the 2DEG to form fractionally charged excitons $h$QE$_n$. The previously found ``anyon exciton'' $h$QE$_3$ is shown to be unstable at any value of $d$. The critical dependence of the stability of different $h$QE$_n$ complexes on the presence of QE's in the 2DEG leads to the observed discontinuity of the PL spectrum at $\nu={1\over3}$ or ${2\over3}$.Comment: 16 pages, 14 figures, submitted to PR

First observation of a narrow charm-strange meson DsJ(2632) -> Ds eta and D0 K+

We report the first observation of a charm-strange meson DsJ(2632) at a mass of 2632.6+/-1.6 MeV/c^2 in data from SELEX, the charm hadro-production experiment E781 at Fermilab. This state is seen in two decay modes, Ds eta and D0 K+. In the Ds eta decay mode we observe an excess of 49.3 events with a significance of 7.2sigma at a mass of 2635.9+/-2.9 MeV/c^2. There is a corresponding peak of 14 events with a significance of 5.3sigma at 2631.5+/-1.9 MeV/c^2 in the decay mode D0 K+. The decay width of this state is <17 MeV/c^2 at 90% confidence level. The relative branching ratio Gamma(D0K+)/Gamma(Dseta) is 0.16+/-0.06. The mechanism which keeps this state narrow is unclear. Its decay pattern is also unusual, being dominated by the Ds eta decay mode.Comment: 5 pages, 3 included eps figures. v2 as accepted for publication by PR