Identification of the protease-binding domain in the N-terminal region of the influenza A virus matrix protein M1]

A region responsible for protease binding by influenza virus (Flu) matrix protein M1 was identified. Trypsin binding was attributed to the N-terminal 9-kDa fragment obtained by hydrolyzing M1 with formic acid. The binding was inhibited by monoclonal antibodies (mAb) to the N-terminal moiety and by antiserum to region 21-45 of M1, whereas mAb to the middle and C-terminal regions had no effect. Thus, the protease-binding domain (PBD) was mapped to the N-terminal moiety of M1.     

Branching dendrites with resonant membrane: a “sum-over-trips” approach

Dendrites form the major components of neurons. They are complex branching structures that receive and process thousands of synaptic inputs from other neurons. It is well known that dendritic morphology plays an important role in the function of dendrites. Another important contribution to the response characteristics of a single neuron comes from the intrinsic resonant properties of dendritic membrane. In this paper we combine the effects of dendritic branching and resonant membrane dynamics by generalising the “sum-over-trips” approach (Abbott et al. in Biol Cybernetics 66, 49–60 1991). To illustrate how this formalism can shed light on the role of architecture and resonances in determining neuronal output we consider dual recording and reconstruction data from a rat CA1 hippocampal pyramidal cell. Specifically we explore the way in which an I _h current contributes to a voltage overshoot at the soma.     

Understanding the Effects of Molecular Dopant on n‐Type Organic Thermoelectric Properties

Molecular doping is a powerful method to fine‐tune the thermoelectric properties of organic semiconductors, in particular to impart the requisite electrical conductivity. The incorporation of molecular dopants can, however, perturb the microstructure of semicrystalline organic semiconductors, which complicates the development of a detailed understanding of structure–property relationships. To better understand how the doping pathway and the resulting dopant counterion influence the thermoelectric performance and transport properties, a new dimer dopant, (N‐DMBI)₂, is developed. Subsequently, FBDPPV is then n‐doped with dimer dopants (N‐DMBI)₂, (RuCp*mes)₂, and the hydride‐donor dopant N‐DMBI‐H. By comparing the UV–vis–NIR absorption spectra and morphological characteristics of the doped polymers, it is found that not only the doping mechanism, but also the shape of the counterion strongly influence the thermoelectric properties and transport characteristics. (N‐DMBI)₂, which is a direct electron‐donating dopant with a comparatively small, relatively planar counterion, gives the best power factor among the three systems studied here. Additionally, temperature‐dependent conductivity and Seebeck coefficient measurements differ between the three dopants with (N‐DMBI)₂ yielding the best thermoelectric properties. The results of this study of dopant effects on thermoelectric properties provide insight into guidelines for future organic thermoelectrics.     

The Curie principle and the morphological diversity of Pandorina morum (Müll.) Bory colonies (Volvocaceae)

Morphological diversity of polyhedral colonies of Pandorina morum cultivated in the artificial environment approximating ecologically pure natural environment was studied. 4-, 6-, and 8-cell colonies were observed to occur most frequently in populations. These colonies tend to produce the most symmetrical shape at each of their growth stage. Two of the three theoretically possible combinatory types of 16-cell colonies were certainly determined: -43m and 222. These two types share a common character; the presence in the point group of symmetry of three mutually perpendicular twofold axes stressing the absence of locomotory specialization in the cells and allowing free rotation of the colony in space. This result was interpreted in the context of Curie's dis-symmetry principle stating that symmetry of an evolving object is disturbed only if it is not confined within the symmetry of the environment.     

Auxin abolishes inhibitory effects of methylcyclopropen and amino oxyacetic acid on pollen grain germination,pollen tube growth,and the synthesis of ACC in petunia

As established by us earlier, ethylene behaves as a regulator of germination, development, and growth of male gametophyte during the progamic phase of fertilization. However, the mechanisms of the regulation of these processes remain so far unstudied. It is believed that the main factor providing variety of the ethylene responses is its interaction with other phytohormones. According to our working hypothesis, ethylene controls germination of pollen grains (PGs) and growth of pollen tubes (PTs) by interacting with auxin, which, as the available data indicate, is likely a key regulator of plant cell polarization and morphogenesis and one of the factors modulating the biosynthesis of ethylene at the level of ACC-synthase gene expression. In the present work, on germinating in vitro male gametophyte and the pollen-stigma system for petunia (Petunia hybrida L.) effects of phytohormones (ethylene and IAA) and known blockers repressing ethylene reception (1-methylcyclopropene, 1-MCP), the synthesis of ACC (amino oxyacetic acid, AOA) and transport IAA (triyodbenzoynaya acid, TYBA) on PGs germination, PTs growth and the synthesis of ACC were investigated. According to the data obtained, exogenous ethylene and IAA stimulated both PGs germination and PTs growth. 1-MCP and TYBA completely inhibited the first process, whereas IAA abolished the inhibitory action of 1-MCP and AOA on both the above processes. Etrel only partially weakened the inhibitory effect of TYBA. Examination of ACC synthesis modulation with AOA showed that IAA does not affect the level of ACC in germinating in vitro male gametophyte and nonpollinated stigmas, while this phytohormone insignificantly raised the level of ACC and abolished the inhibitory effect of AOA on its synthesis in the pollenstigma system. Pollination of stigmas with the pollen preliminarily treated with 1-MCP led to 2.5-fold decline in both the rate of PT growth and the level of ACC. At the same time, IAA abolished the inhibitory action of 1-MCP recovering the synthesis of ACC and growth of PTs to the control values. All these results, taken together, provide evidence for the interaction of the signal transduction pathways of ethylene and auxin at the level of ACC biosynthesis in the course of germination and growth of petunia male gametophyte during the progamic phase of fertilization.     

Experimental and mathematical simulation of plant growth promoting rhizobacteria and plant interaction under cadmium stress

Bacterial inoculants of the commercially available plant growth promoting rhizobacteria (PGPR) Arthrobacter mysorens 7, Flavobacterium sp. L30, and Klebsiella mobilis CIAM 880 were selected to obtain ecologically safe barley crop production on cadmium (Cd) polluted soils. All the PGPR immobilized 24–68% soluble cadmium from soil suspension. A. mysorens 7 and K. mobilis CIAM 880 were highly resistant to Cd and grew in up to 1 and 3 mmol CdCl₂ on DAS medium respectively. All PGPR were able to fix nitrogen (276–1014 nmol mg^–1 bacterial DW) and to produce indole acetic acid (IAA) (126–330 nmol mg^–1 bacterial DW) or ethylene (4.6–13.5 nmol bacterial DW). All the PGPR actively colonized barley root system and rhizosphere and significantly stimulated root elongation of barley seedlings (up to 25%), growing on soil containing 5 or 15 mg Cd kg^–1 of soil. Created in the simulation mathematical model confirms our hypothesis that PGPR beneficial effect on barley growing under Cd-stress is a complex process. One of mechanisms underlying this effect might be increase of bacterial migration from rhizoplane to rhizosphere, where PGPR bind soluble free Cd ions in biologically unavailable complex forms. Among the studied PGPR K. mobilis CIAM 880 was the most effective inoculant. Inoculation with K. mobilis CIAM 880 of barley plants growing on Cd contaminated soil (5 mg Cd kg^–1 of soil) under field conditions increased by 120% grain yield and 2-fold decreased Cd content in barley grain. The results suggest that the using K. mobilis CIAM 880 is an effective way to increase the plant yield on poor and polluted areas.     

Change in Lectin Specificity of Winter Wheat Seedlings in the Course of Infection with Mycoplasms

The activity of soluble lectins in leaves and roots of seedlings of winter wheat (Triticum aestivum L.) cultivar Mironovskaya 808 increased 1 day and 2 days, respectively, after infection with the mycoplasma Acholeplasma laidlawii 118. Analysis of acid-soluble proteins of wheat leaves by PAGE revealed the appearance of 22- and 20-kDa polypeptides, the disappearance of a 14-kDa polypeptide, and an increase in the content of polypeptides with molecular weights of 76, 48, 25, and 18 kDa. The 18-kDa polypeptide is a subunit of wheat germ agglutinin. A change in the activity of lectins may be a nonspecific response of plants to infection with the pathogen.     

Effect of protein deficiency in the female rat diet during pregnancy and lactation on the activity of the membrane and soluble forms of digestive enzymes in the offspring small intestine

Protein deficiency in female rats diet during pregnancy and lactation resulted in deceleration of induction of sucrase both forms in the jejunum and ileum; in acceleration of induction of the maltase membrane from in the jejunum; and in suppression of the lactase membrane form in the ileum; in earlier forming of the adult-type distribution of activity of the membrane form of intestinal alkaline phosphatase and in a decrease in activity of the enzyme soluble form. The findings are corroborated by a suppression of activities of the membrane and soluble forms of the small intestine digestive enzymes in 30-day old rat pups fed with a control (adequate) ration starting 21 days after the birth.