Electromagnetic field effects on <Emphasis Type="Italic">Artemia</Emphasis> hatching and chromatin state

The influence of magnetic fields on hatching and chromatin state of brine shrimp, Artemia sp., was investigated. Dry Artemia cysts were exposed to a magnetic field of intensity 25 mT for 10 min. The magnetic field was applied in different variants: constant field, rotating field of different directions (right-handed and left-handed) and different magnet polarization. The effect of ultra wideband pulse radiation and microwave radiation was also investigated. The energy density on the surface of object exposed to ultra wideband pulse radiation was 10⁻², 10⁻³, 10⁻⁴, 10⁻⁵ and 10⁻⁶ W/cm², the power of microwave radiation was 10⁻⁴ and 10⁻⁵ W/cm², exposure time - 10 s. After incubation of the cysts for 48 hours in sea water the hatching percentage of Artemia from exposed cysts was higher than in controls. The number of heterochromatin granules was significantly higher in the nauplia (newborn larvae of Artemia) developed from cysts that had been exposed to magnetic and electromagnetic fields. The data obtained demonstrate an increase in percentage hatching of Artemia cysts after treatment with magnetic and electromagnetic fields and chromatin condensation in nauplia. We have also shown different effects of right-handed and left-handed rotating magnetic fields on these processes.     

Polarization selectivity of interaction of DNA molecules with X-ray radiation

The optimum form of a long helical molecule, which DNA is, has been calculated in terms of the classical electromagnetic theory. Three different methods of classical electrodynamics are used: the theory of dipole radiation of electromagnetic waves, the energetic power approach, and a helical model of molecules of chiral medium. In all three cases, an identical result for the optimum geometrical form of a long spiral molecule has been obtained. The lead angle between the tangent to the helix and the plane normal to the axis of the helix should be equal to 24.5 degrees. This condition imposes restrictions on the radius and the pitch of the helical molecule. The experimentally measured geometrical characteristics of the DNA molecule satisfy the theoretically calculated condition precisely enough. Having the optimum geometrical form, the DNA molecule is not influenced by a circularly right-polarized electromagnetic wave in the soft X-ray range λ = 7–8 nm. This wave, for which the right-handed DNA molecule is “transparent,” should propagate orthogonally to the helix axis and form a right-handed screw in space. The wave radiated by the right-handed DNA molecule orthogonally to helix axis in the range of λ ≈ 7–8 nm has, accordingly, the left-handed circular polarization. The polarization selectivity of the DNA molecule by the action of X-ray radiation is exhibited strongly enough in the wavelength range of λ ≈ 1–35 nm. The results obtained are valid for any distribution of electric currents in DNA, i.e., for any sequence of nitrogenous bases in DNA.     

Unique Combinations of βαβ-Units and Π-Like Modules in Proteins and Specific Features of Their Amino Acid Sequences

Possible combinations of βαβ-units and Π-like modules in proteins in both right- and left-handed forms have been analyzed in detail. The correlation between the mutual arrangement of the structural elements in the polypeptide chain and their handedness has been shown. In the βαβΠ combinations, which is encountered most frequently in proteins, the Π-module follows the βαβ unit along the chain and both elements are right-handed. In the Πβαβ combinations, where the Π-module is located at the N end and the βαβ-unit follows it, the former is left-handed and the latter is right-handed. In relatively rare combinations of the left-handed βαβ-units and right-handed Π-modules, the βαβ-unit follows Π-module in the chain. The combinations of left-handed Π-modules and the left-handed βαβ-units are unobservable in proteins. It has also been shown that the Π-modules with a β-strand—α-helix—arch—β-strand structure are observed in proteins only in a right-handed form and half of them (51%) contains cis-prolines in their arches. These arches of nonhomologous proteins, as well as the positions of cis-prolines, nearly coincide when superimposed. The superimposed Π-modules also demonstrate that their overall folds are very similar. Structural alignment of their amino acid sequences has shown that the Π-modules have very similar sequence patterns of the key hydrophobic, hydrophilic, glycine, and cis-proline residues.     

Conformational studies of polymers and copolymers of L-aspartate ester. II. Infrared studies and the factors involved in the formation of the omega-helix

It has already been show that the helix senses of poly(β-benzyl L -aspartate) and poly(β-methyl L -aspartate) are left-handed, while the poly esters of n-propyl, isopropyl, n-butyl, and phenethyl L -asparate are all right-handed. The effect of changes in helix sense from the left-handed to the right-handed α-helical form on the infrared spectra of copolymers of benzyl L -aspartate with ethyl, n-butyl, isopropyl, n-propyl, and phenethyl L -aspartate have been studied. Those show that for the right-handed helical form the amide band frequencies fall within the range given by Elliott,⁷ while for the left-handed form the frequencies are higher. The frequency ranges for the two helix senses are given and have been used to show that poly (β-n-propyl L -aspartate) in chloroform solution undergoes a transition from the right-handed to the left-handed helix form on heating. Polarized infrared studies of the different copolymers show that the disposition of the side chain ester groups is different for the two forms. Although methyl L -aspartate forms a left-handed α-helix similar to benzyl L -aspartate, the introduction of methyl L -aspartate residues into poly (β-benzyl L -aspartate) prevents the formation of the ω-helix. The factors involved in the formation of this helix form are discussed.     

Effects of invasive Green Iguanas (<Emphasis Type="Italic">Iguana iguana</Emphasis>) on seed germination and seed dispersal potential in southeastern Puerto Rico

Green Iguanas (Iguana iguana) are invasive in Puerto Rico due to a variety of negative economic effects, yet we know very little about their ecological impacts. Because they are herbivorous, defecate intact seeds, move through the forest, and have long gut-passage times, Green Iguanas may affect seed germination and seed dispersal. In summer 2013, a total of 258 Green Iguana scat samples were collected at the Humacao Natural Reserve in southeastern Puerto Rico. Seeds extracted from scat and collected from fruit were planted under common garden conditions using experimental treatments designed to tease apart the effects of feces, fruit, and ingestion on seed germination. Green Iguanas decreased the time for seeds to germinate in Ficus spp. by removing fruit pulp, but had no effect on germination of native Annona glabra seeds. For non-native P. pterocarpus and Pterocarpus spp., Green Iguanas produced conflicting results, decreasing the percentage of seeds germinating, but at the same time, reducing the time for seeds to germinate. Green Iguanas likely disperse most seeds beyond the canopies of parental tree at our site. Government and economic resources are being used to eradicate Green Iguana populations in Puerto Rico, but the lack of consistent effects of Green Iguanas on seed germination for the plant species consumed at our site complicates generalizing about their ecological effects and developing management plans that minimize negative effects for native plant communities. We recommend additional studies that target both species of particular concern, such as threatened native or invasive species, as well as studies of sensitive habitats in Puerto Rico.     

Subunit b-dimer of the Escherichia coli ATP synthase can form left-handed coiled-coils

One remaining challenge to our understanding of the ATP synthase concerns the dimeric coiled-coil stator subunit b of bacterial synthases. The subunit b-dimer has been implicated in important protein interactions that appear necessary for energy conservation and that may be instrumental in energy conservation during rotary catalysis by the synthase. Understanding the stator structure and its interactions with the rest of the enzyme is crucial to the understanding of the overall catalytic mechanism. Controversy exists on whether subunit b adopts a classic left-handed or a presumed right-handed dimeric coiled-coil and whether or not staggered pairing between nonhomologous residues in the homodimer is required for intersubunit packing. In this study we generated molecular models of the Escherichiacoli subunit b-dimer that were based on the well-established heptad-repeat packing exhibited by left-handed, dimeric coiled-coils by employing simulated annealing protocols with structural restraints collected from known structures. In addition, we attempted to create hypothetical right-handed coiled-coil models and left- and right-handed models with staggered packing in the coiled-coil domains. Our analyses suggest that the available structural and biochemical evidence for subunit b can be accommodated by classic left-handed, dimeric coiled-coil quaternary structures.     

Right-Left Symmetry in Phyllotaxy and Imbrication of Flowers of Hibiscus furcartus L.

The phyllotaxy in Hibiscus furcartus is spiral. It is foundthat there is a general tendency for lateral branches to acquirethe same sense (right-handed or left-handed) of phyllotaxy asthe parent branch. H. furcartus has two kinds of flowers, right-handedflowers with clockwise imbricated petals and left-handed flowerswith anticlockwise imbricated petals. It is found that brancheswith right-handed phyllotaxy yield only left-handed flowersand those with left-handed phyllotaxy yield only right-handedflowers. Hibiscus furcartus L., phyllotaxy, imbrication of flowers     

Supernumerary (B) chromosomes in populations of Picea abies (L.) H. Karst. from Western Rhodopes (Bulgaria)

Investigations on B chromosomes found for the first time for Picea abies (L.) H. Karst. have been conducted. Seeds of Picea abies from two populations of Western Rhodopes (Bulgaria) located at the southern border of species range, and protected according to Bern Convention and EC Habitat Directive were collected for this study. Mixoploidy was detected in some germinating seeds of Picea abies. It was found that metaphase cells of germinating seeds contain 0–4 B chromosomes of both metacentric and submetacentric types. The variability of B chromosomes number and their occurrence was observed. Along with B chromosomes, some chromosome aberrations such as fragments and ring chromosomes were revealed in metaphase cells of Picea abies from studied populations. The possible adaptive role of B chromosomes presence for Picea spp. is discussed.     

Transition of bacterial flagella from helical to straight forms with different subunit arrangements.

We have found that several kinds of helical flagella from Salmonella and Escherichia become straight in the presence of 0·5 m-citric acid at pH values below 4·0, while the straight flagella from a mutant Salmonella (SJ814) are transformed into a helical shape under the same conditions. These transformations are reversible and transitional.Current models of bacterial flagella (Calladine, 1976,1978; Kamiya, 1976) predict that the family of distinct wave-forms should include two types of straight flagella, which have either an extreme right-handed twist (about 7 ° at the surface of the flagellum) or an extreme left-handed twist (2 ° to 3 °). As the inclination of the near-longitudinal rows of subunits in the Salmonella SJ814 flagellum (O'Brien &; Bennett, 1972) agrees closely with the degree of twisting predicted for the right-handed type, this flagellum has been considered to be the right-handed type. We have determined that the basic (1-start) helix in flagella is right-handed, using the method of Finch (1972). This fact, together with the selection rule (O'Brien &; Bennett, 1972), strongly suggests that the near-longitudinal rows in an SJ814 flagellum are right-handed, in agreement with the prediction. However, our optical diffraction and X-ray diffraction studies have revealed that the near-longitudinal rows of subunits in the citric acid-induced straight flagella and in the straight flagella from a mutant E. coli (Kondoh &; Yanagida, 1975) tilt at an angle of 2 ° to 3 ° with respect to the flagellar axis. This inclination is probably left-handed. Thus the predicted presence of the two types of straight flagella seems to be proved.     

13C-nmr chemical shift and conformation of L-alanine residues incorporated into poly(β-benzyl L-aspartate) in the solid state

¹³C-nmr spectra of poly(β-benzyl L-aspartate) containing ¹³C-enriched [3-¹³C]L -alanine residues in the solid state were recorded by the cross polarization–magic angle spinning method, in order to elucidate the conformation-dependent ¹³C chemical shifts of L -alanine residues taking various conformations such as the antiparallel β-sheet, the right-handed α-helix, the left-handed α-helix, and the left-handed ω-helix forms obtained by appropriate treatment. The latter two conformations for L -alanine residues are achieved when L -alanine residues are incorporated into poly(β-benzyl L -aspartate). We found that the alanine C_β carbon show significant ¹³C chemical shift displacement depending on conformational change, and gave the ¹³C chemical shift values at about 17 ppm for the left-handed ω-helix, 14 ppm for the left-handed α-helix, 15.5 ppm for the right-handed α-helix, and 21.0 ppm for the antiparallel β-sheet relative to tetramethylsilane.     

Growth Dynamics of Salmonella enterica Strains on Alfalfa Sprouts and in Waste Seed Irrigation Water

Alfalfa sprouts and other seed sprouts have been implicated in numerous outbreaks of salmonellosis. The source of these epidemics appears to have been low-level contamination of seeds by Salmonella bacteria that developed into clinically significant populations during the seed germination process. To test the possibility that Salmonella enterica strains carry host range determinants that allow them to grow on alfalfa, strains isolated from alfalfa or other sources were surveyed for their ability to grow on germinating alfalfa seeds. An S. enterica serovar Cubana strain originally isolated from contaminated alfalfa sprouts multiplied most rapidly during the initial 24 h of the seed germination process. Germinating alfalfa seeds supported the multiplication of S. enterica cells prior to the emergence of the root radicle at 72 h. Thereafter, much lower rates of multiplication were apparent. The ability of S. enterica to grow on germinating alfalfa seeds was independent of the serovar, isolation source, or virulence of the strain. Isolates obtained from alfalfa attained population levels similar to those observed for strains isolated from contaminated meat products or stools. Each of the strains could be detected in the waste irrigation water, with populations being strongly correlated with those detected on the germinating alfalfa seeds. The S. enterica strains were capable of utilizing the waste irrigation water as a sole carbon and nitrogen source. S. enterica strains thus appear to grow saprophytically on soluble organics released from seeds during early phases of germination. The ability to detect S. enterica in the waste irrigation water early in the germination process indicates that this method may be used as a simple way to monitor the contamination of sprouts during commercial operations.     

Crystal structure of the left-handed archaeal RadA helical filament: identification of a functional motif for controlling quaternary structures and enzymatic functions of RecA family proteins

The RecA family of proteins mediates homologous recombination, an evolutionarily conserved pathway that maintains genomic stability by protecting against DNA double strand breaks. RecA proteins are thought to facilitate DNA strand exchange reactions as closed-rings or as right-handed helical filaments. Here, we report the crystal structure of a left-handed Sulfolobus solfataricus RadA helical filament. Each protomer in this left-handed filament is linked to its neighbour via interactions of a β-strand polymerization motif with the neighbouring ATPase domain. Immediately following the polymerization motif, we identified an evolutionarily conserved hinge region (a subunit rotation motif) in which a 360° clockwise axial rotation accompanies stepwise structural transitions from a closed ring to the AMP–PNP right-handed filament, then to an overwound right-handed filament and finally to the left-handed filament. Additional structural and functional analyses of wild-type and mutant proteins confirmed that the subunit rotation motif is crucial for enzymatic functions of RecA family proteins. These observations support the hypothesis that RecA family protein filaments may function as rotary motors.     

Analysis of Proteome Profile in Germinating Soybean Seed,and Its Comparison with Rice Showing the Styles of Reserves Mobilization in Different Crops

Background

Seed germination is a complex physiological process during which mobilization of nutrient reserves happens. In different crops, this event might be mediated by different regulatory and metabolic pathways. Proteome profiling has been proved to be an efficient way that can help us to construct these pathways. However, no such studies have been performed in soybean germinating seeds up to date.

Results

Proteome profiling was conducted through one-dimensional gel electrophoresis followed by liquid chromatography and tandem mass spectrometry strategy in the germinating seeds of soybean (glycine max). Comprehensive comparisons were also carried out between rice and soybean germinating seeds. 764 proteins belonging to 14 functional groups were identified and metabolism related proteins were the largest group. Deep analyses of the proteins and pathways showed that lipids were degraded through lipoxygenase dependent pathway and proteins were degraded through both protease and 26S proteosome system, and the lipoxygenase could also help to remove the reactive oxygen species during the rapid mobilization of reserves of soybean germinating seeds. The differences between rice and soybean germinating seeds proteome profiles indicate that each crop species has distinct mechanism for reserves mobilization during germination. Different reserves could be converted into starches before they are totally utilized during the germination in different crops seeds.

Conclusions

This study is the first comprehensive analysis of proteome profile in germinating soybean seeds to date. The data presented in this paper will improve our understanding of the physiological and biochemical status in the imbibed soybean seeds just prior to germination. Comparison of the protein profile with that of germinating rice seeds gives us new insights on mobilization of nutrient reserves during the germination of crops seeds.     

Ethylene antagonizes the inhibition of germination in Arabidopsis induced by salinity by modulating the concentration of hydrogen peroxide

The capacity of plants to achieve successful germination and early seedling establishment under high salinity is crucial for tolerance of plants to salt. The gaseous hormone ethylene has been implicated in modulating salt tolerance, but the detailed role of how ethylene modulates the response of early seedling establishment to salt is unclear. To better understand the role of the ethylene signal transduction pathway during germination and seedling establishment, an ethylene insensitive mutation (ein2-5) and an ethylene sensitive mutation (ctr1-1) of Arabidopsis were analyzed under saline conditions and compared with the wild type plant (Col-0) as control. High salinity (>100?mM NaCl) inhibited and delayed germination. These effects were more severe in the ethylene insensitive mutants (ein2-5) and less severe in the constitutive ethylene sensitive plants (ctr1-1) compared with Col-0 plants. Addition of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) or inhibitors of ethylene action implied that ethylene was essential for early seedling establishment under normal and saline conditions. Salt stress increased the endogenous concentration of hydrogen peroxide (H₂O₂) in germinating seeds and ACC reduced its concentration. Our results suggest that ethylene promotes germination under salinity by modulating the endogenous concentration of H₂O₂ in germinating seeds. These findings demonstrate that ethylene is involved in regulating germination as an initiator of the process rather than consequence, and that ethylene promotes germination by modulating the endogenous concentration of H₂O₂ in germinating seeds under salinity.     

Effect of extremely low frequency magnetic fields on the seedlings of wild plants growing in Central Yakutia

It was shown that permanent (B = 50 μT, horizontal plane, direction to the north) and alternating magnetic fields (North–South direction) exerted influences on seed germination as well as on cytological and biochemical features of seedlings characteristic of investigated species (Lepidium apetalum, Artemisia vulgaris, A. jacutica, and A. dracunculus) of wild plants growing in Central Yakutia. Under the effect of permanent magnetic field (MF), germinating capacity of seeds decreased (except for A. vulgaris), whereas alternating MF of different frequencies improved their germinating capacity, except for L. apetalum and A. jacutica at frequencies of 200 and 300 Hz, respectively. Under permanent MF, the rate of lipid peroxidation in the tissues of the seedlings decreased, whereas the content of low molecular weight antioxidants rose; when the plants were exposed to an alternating magnetic field, the content of MDA and peroxidase activity increased, and the content of low molecular weight antioxidants followed an ambiguous pattern.     

Asparagine Enhances Starch Accumulation in Developing and Germinating Lupin Seeds

Regulation of starch accumulation in yellow (Lupinus luteus L.), white (L. albus L.), and Andean lupin (L. mutabilis Sweet) developing and germinating seeds was investigated. Research was conducted on cotyledons isolated from developing seeds as well as on organs of germinating seeds, that is, isolated embryo axes, excised cotyledons, and seedling axes and cotyledons. All organs were cultured in vitro for 96 h in different carbon (60 mM sucrose) and nitrogen (35 mM asparagine or 35 mM nitrate) conditions. Ultrastructure observation showed one common pattern of changes in the number and size of starch granules caused by sucrose, asparagine, and nitrate in both developing and germinating seeds. Sucrose increased the number and size of starch granules. Asparagine additionally increased starch accumulation (irrespective of sucrose nutrition) but nitrate had no effect on starch accumulation. Asparagine treatment resulted in a significant decrease in soluble sugar level in all organs of germinating lupin seeds of the three species investigated. The above-mentioned changes were most clearly visible in white lupin organs. In white lupin, starch granules were visible even in cells of sucrose-starved isolated embryo axes where advanced autophagy occurs. The importance of asparagine-increased starch content in the creation of a strong source–sink gradient in developing and germinating lupin seeds is discussed.     

Nonalternating purine pyrimidine sequences can form stable left-handed DNA duplex by strong topological constraint

In vivo, left-handed DNA duplex (usually refers to Z-DNA) is mainly formed in the region of DNA with alternating purine pyrimidine (APP) sequence and plays significant biological roles. It is well known that d(CG)_n sequence can form Z-DNA most easily under negative supercoil conditions, but its essence has not been well clarified. The study on sequence dependence of Z-DNA stability is very difficult without modification or inducers. Here, by the strong topological constraint caused by hybridization of two complementary short circular ssDNAs, left-handed duplex part was generated for various sequences, and their characteristics were investigated by using gel-shift after binding to specific proteins, CD and T_m analysis, and restriction enzyme cleavage. Under the strong topological constraint, non-APP sequences can also form left-handed DNA duplex as stable as that of APP sequences. As compared with non-APP sequences, the thermal stability difference for APP sequences between Z-form and B-form is smaller, which may be the reason that Z-DNA forms preferentially for APP ones. This result can help us to understand why nature selected APP sequences to regulate gene expression by transient Z-DNA formation, as well as why polymer with chirality can usually form both duplexes with left- or right-handed helix.     

Natural DNA sequences can form left-handed helices in low salt solution under conditions of topological constraint

The conformation of DNA that originates from association of complementary single-stranded circles (form V DNA) is investigated in solution at low salt concentration. It is shown that circular dichroism extended to the far ultraviolet region (down to 165 nm) represents a powerful tool for determination of the handedness of double helical DNAs in solution. The positive intense band at 186 nm followed by a strong negative band around 170 nm is characteristic of all right-handed helical forms (B,A) of DNA, whereas the circular dichroism spectrum of the Z form of poly[d(G-C)] of opposite helical sense represents a quasi inversion of these far ultraviolet bands. Thus, form V DNA is found to represent a co-existence of left-handed Z-type and right-handed B double helical stretches in addition to negative superturns. The Raman spectrum of form V DNA provides further support for the contribution of a left-handed double helical conformation, as shown by comparison to the high resolution Raman spectra of poly[d(G-C)] in the Z and B forms.The analysis of present spectroscopic data and the analysis of occurrence of alternating [d(G-C)] purine-pyrimidine sequences in the form V DNA used strongly suggest that in DNA of natural sequence, topological constraint may generate left-handed double helices, a conformation thought so far to be limited to the alternating [d(G-C)] sequences. Such structure could play a role in recognition and regulation of gene expression.     

Development of the system of cognitive functions in right- and left-handed boys aged six to seven years: A study taking into consideration specific features of early ontogeny

Characteristics of early ontogeny and the formation of cognitive functions of left-and right-handed boys six to seven years of age have been studied with the genesis of handedness taken into account. A comparative analysis of cognition in right-and left-handed children has been performed using a unified approach to the history of early ontogeny with special emphasis on cognitive functions. The negative effect of pathological pregnancies and births, as well as disturbances in early ontogeny, on the development of cognitive functions in both left-and right-handed boys has been shown. The most “vulnerable” functions in right-handed boys with a history of various pathologies are the organization of activity and visuospatial perception; in left-handed boys, these are fine motor skills and speech development. In the absence of pathologies in the medical history, significantly higher indices of the organization of activity and visuomotor coordination have been found in right-handed boys and significantly higher indices of visuospatial perception, in left-handed boys.     

Conformational studies of polymers and copolymers of L-aspartate esters. I. Preparation and solution studies

An alcoholysis method is described for the modification of high molecular weight poly(β-benzyl L -asparatate); by this method the benzyl groups in the polypeptide have been replaced by methyl, ethyl, isopropyl, n-propyl, and phenethyl groups to give a series of copolymers of each of the corresponding aspartate esters with benzyl L -aspartate. By repeating the reactions, replacement of better than 99% has been achieved in some cases to give in effect the homopolymer. Optical rotatory dispersion studies show that of all the systems studied only poly(β-methyl L -aspartate) has the left-handed helix sense, the others are right-handed. It is shown further that the helix sense is not an intrinsic property of the nature of the aspartate side chain. Raising the temperature of chloroform solutions of the right-handed form of the copolymers of benzyl L -aspartate and ethyl L -aspartate results in a transition to the left-handed helix, the temperature of the transition being dependent on the composition of the copolymer. Also poly(β-n-propyl L -aspartate) undergoes a transition from the right- to the left-handed helix form at 59°C. These results suggest a general pattern of behavior of poly(aspartate esters) and that with suitable conditions of solvent and temperature they may be in either the right- or left-handed helical form.