Morphology and composition of the surface of Mars: Mars Odyssey THEMIS results

The Thermal Emission Imaging System (THEMIS) on Mars Odyssey has produced infrared to visible wavelength images of the martian surface that show lithologically distinct layers with variable thickness, implying temporal changes in the processes or environments during or after their formation. Kilometer-scale exposures of bedrock are observed; elsewhere airfall dust completely mantles the surface over thousands of square kilometers. Mars has compositional variations at 100-meter scales, for example, an exposure of olivine-rich basalt in the walls of Ganges Chasma. Thermally distinct ejecta facies occur around some craters with variations associated with crater age. Polar observations have identified temporal patches of water frost in the north polar cap. No thermal signatures associated with endogenic heat sources have been identified.     

A comparative epidemiological study of hantavirus infection in Japan and Far East Russia

Hantaviruses are causative agents of some severe human illnesses, including hemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS). The viruses are maintained by rodent hosts, and humans acquire infection by inhaling virus-contaminated excreta from infected animals. To examine the epidemiology of hantavirus infections in Japan and Far East Russia, we conducted epidemiological surveys in these regions. In Japan, anti-hantavirus antibodies were found in four rodent species, Clethrionomys rufocanus, Rattus norvegicus, R. rattus, and Apodemus speciosus. Although no new HFRS cases have been officially reported over the past 20 years in Japan, one member of the Japan Ground Self-Defense Force did test positive for hantavirus antibody. Repeated surveys in Far East Russia have revealed that two distinct hantavirus types cause severe HFRS in this region. Hantavirus sequences identified from A. peninsulae, fetal HFRS cases in Vladivostok, and Amur virus are highly similar to each other (> 92% identity), but they are less similar (approximately 84% identity) to the prototypical Hantaan virus, which is carried by A. agrarius. Phylogenetic analysis also indicates that Amur and A. peninsulae-associated viruses are distinct from Hantaan virus, suggesting that A. peninsulae is the reservoir animal for Amur virus, which causes severe HFRS. From HFRS patients in the Khabarovsk region, we identified viruses with nucleotide sequences that are more similar to Far East virus (> 96%identity) than to the Hantaan (88-89% identity) or Amur (81-83% identity) viruses. Phylogenetic analysis also indicates that the viruses from Khabarovsk HFRS patients are closely related to the Far East virus, and distinct from Amur virus.     

Changes in Phosphate Fractions Extracted From Different Organs of Phosphorus Starved Nitrogen Fixing Pea Plants

The present work investigates the impact of phosphorus (P) starvation on plant growth, symbiotic nitrogen fixation, and internal P status (determined as extracted P fractions) of leaves, roots, and nodules of 27-days–old pea (Pisum sativum L) plants inoculated with Rhizobium leguminosarum bv viciae strain D293. The procedure of separation of organic and inorganic P compounds in 10% perchloric acid (HCLO₄) and the absorption of nucleotides in active charcoal gave several fractions, containing different phosphorus compounds, which were extracted and determined as inorganic phosphate after combustion. These are acid soluble and insoluble P, sugar P, nucleotide P, and inorganic P. The P starvation of plants inhibited significantly plant dry mass accumulation, nodulation rate and specific nitrogenase activity of nodules. These results were accompanied with lower quantities of total P per plant, acid soluble and acid non-soluble P fractions in all plant organs. The inhibited accumulation of P in the acid soluble P fraction was associated with decrease of sugar, nucleotide and inorganic P in all plant organs. The most negatively affected were all P fractions extracted from nodules and leaves. The low content of inorganic P in the stressed plant tissues was regarded as primary reason for induced alterations in the content of analyzed P fractions.     

A protocol to avoid precocious flowering of sunflower plantlets in vitro

Precocious flowering in in vitro plantelets of sunflower is one of the unfavourable phenomena when using tissue endure. In this sundy additional evidence is presented on precocious flowering of sunflower regenerats. Three day/night cycles (16/8h. 12/12h and 8/16h) and some modifications of media were investigated. Under standard conditions (16/8h day night. 25C) 62% of the plamlels formed flowers, while 55% formed flowers when grown in 12/12 h day. night at 20C and 31% when plantiets were grown under cultivation conditions of 8/16h day-night ai 20C. According to the results obtained, precocious flowering of sunflower plantlets in tesl tubes depends on culture conditions, nutrition medium and genotype. It was found that 20C and 8/16h diiy/nighl was the most favourable condition to reduce precocious flowering of sunflower planllels in the lest tuhe. Modified nutrition media can also help to reduce in vitro flowering.     

Coevolution of soils and vegetation in the southern taiga (with the Prioksko-Terrasnyi reserve as an example)

A detailed characterization of the relief, parent materials, soils, woody vegetation, and the links between them is given for a small part of the southern taiga zone in the center of the East European Plain. A methodology for determining the vegetation succession patterns on different soils with the use of the selectivity coefficient K is suggested. This coefficient is defined as the ratio between the frequency of occurrence of the given tree species on a given soil and its average frequency of occurrence within the entire analyzed area (in the area of the reserve). The values of K change from 0.2 to 3.6 and indicate positive (K > 1) and negative (K < 1) feedback relationships between the soils and vegetation. Changes in the frequencies of occurrence of different tree species on different soils that took place over 19 years have also been studied. It is shown that spruce has a tendency for settling on podzols, mixed spruce-oak-lime forests tend to develop on podzolized podburs, and lime and oak trees tend to develop on soddy podburs. Birch stands are most often replaced by spruce and pine stands; aspen stands and a part of the birch stands are replaced by lime and oak stands. The ecological plasticity of pine trees and the long age of this tree species ensure the existence of a long transitional succession stage with the predominance of pine. These regularities are important for predicting the further development of forest vegetation.     

Excitation energy partitioning and quenching during cold acclimation in Scots pine

We studied the influence of two irradiances on cold acclimation and recovery of photosynthesis in Scots pine (Pinus sylvestris L.) seedlings to assess mechanisms for quenching the excess energy captured by the photosynthetic apparatus. A shift in temperature from 20 to 5 degrees C caused a greater decrease in photosynthetic activity, measured by chlorophyll fluorescence and oxygen evolution, in plants exposed to moderate light (350 micromol m(-2) s(-1)) than in shaded plants (50 micromol m(-2) s(-1)). In response to the temperature shift, maximal photochemical efficiency of photosystem II (PSII), measured as the ratio of variable to maximal chlorophyll fluorescence (Fv/Fm) of dark-adapted samples, decreased to 70% in exposed seedlings, whereas shaded seedlings maintained Fv/Fm close to initial values. After a further temperature decrease to -5 degrees C, only 8% of initial Fv/Fm remained in exposed plants, whereas shaded plants retained 40% of initial Fv/Fm. Seven days after transfer from -5 to 20 degrees C, recovery of photochemical efficiency was more complete in the shaded plants than in the exposed plants (87 and 65% of the initial Fv/Fm value, respectively). In response to cold stress, the estimated functional absorption cross section per remaining PSII reaction center increased at both irradiances, but the increase was more pronounced in exposed seedlings. Estimates of energy partitioning in the needles showed a much higher dissipative component in the exposed seedlings at low temperatures, pointing to stronger development of non-photochemical quenching at moderate irradiances. The de-epoxidation state of the xanthophyll cycle pigments increased in exposed seedlings at 5 degrees C, contributing to the quenching capacity, whereas significant de-epoxidation in the shaded plants was observed only when temperatures decreased to -5 degrees C. Thermoluminescence (TL) measurements of PSII revealed that charge recombinations between the second oxidation state of Mn-cluster S2 and the semireduced secondary electron acceptor quinone Q(B)- (S2Q(B)-) were shifted to lower temperatures in cold-acclimated seedlings compared with control seedlings and this effect depended on irradiance. Concomitant with this, cold-acclimated seedlings demonstrated a significant shift in the S2 recombination with primary acceptor Q(A)- (S2Q(A)-) characteristic TL emission peak to higher temperatures, thus narrowing the redox potential gap between S2Q(B)- and S2Q(A)-, which might result in increased probability for non-radiative radical pair recombination between the PSII reaction center chlorophyll a (P680+) and Q(A)- (P680+)Q(A)-) (reaction center quenching) in cold-acclimated seedlings. In Scots pine seedlings, mechanisms of quenching excess light energy in winter therefore involve light-dependent regulation of reaction center content and both reaction center-based and antenna-based quenching of excess light energy, enabling them to withstand high excitation pressure under northern winter conditions.     

Submicromorphology of soil magnetic fractions

The spatial and vertical distribution patterns of ferromagnetic particles in soddy-podzolic and chernozemic soils subjected to technogenic loads have been studied. A classification of soil magnetic particles according to their morphological features is suggested. It takes into account the shape and the character of the particles’ surface, which are specified by the genesis of the particles, and may be used for diagnostic purposes.     

ELISA test system for serological diagnosis of bovine parvovirus infection and determination of postvaccinal antibody level

An ELISA test system was developed on the basis of using bovine parvovirus type I intended for revealing antibodies in bovine blood serum in sick, convalescent, and vaccinated animals.     

Time-resolved holography with photoelectrons

Ionization is the dominant response of atoms and molecules to intense laser fields and is at the basis of several important techniques, such as the generation of attosecond pulses that allow the measurement of electron motion in real time. We present experiments in which metastable xenon atoms were ionized with intense 7-micrometer laser pulses from a free-electron laser. Holographic structures were observed that record underlying electron dynamics on a sublaser-cycle time scale, enabling photoelectron spectroscopy with a time resolution of almost two orders of magnitude higher than the duration of the ionizing pulse.