Multi-spectroscopic studies on the interaction between traditional Chinese herb,helicid with pepsin

Study on the binding properties of helicid by pepsin systematically using multi-spectroscopic techniques and molecular docking method, and these interactions comprise biological recognition at molecular level and backbone of biological significance in medicine concerned with the uses, effects, and modes of action of drugs. We investigated the mechanism of interaction between helicid and pepsin by using various spectroscopic techniques viz., fluorescence spectra, UV–Vis absorption spectra, circular dichroism (CD), 3D spectra, synchronous fluorescence spectra and molecular docking methods. The quenching mechanism associated with the helicid–pepsin interaction was determined by performing fluorescence measurements at different temperatures. From the experimental results show that helicid quenched the fluorescence intensity of pepsin via a combination of static and dynamic quenching process. The binding constants (K_a) at three temperatures (288, 298, and 308 K) were 7.940?×?10⁷, 2.082?×?10⁵ and 3.199?×?10⁵ L mol^?1, respectively, and the number of binding sites (n) were 1.44, 1.14, and 1.18, respectively. The n value is close to unity, which means that there is only one independent class of binding site on pepsin for helicid. Thermodynamic parameters at 298 K were calculated as follows: ΔH^o (??83.85 kJ mol^?1), ΔG^o (??33.279 kJ mol^?1), and ΔS^o (??169.72 J K^?1 mol^?1). Based on thermodynamic analysis, the interaction of helicid with pepsin is driven by enthalpy, and Van der Waals’ forces and hydrogen bonds are the main forces between helicid and pepsin. A molecular docking study further confirmed the binding mode obtained by the experimental studies. The conformational changes in the structure of pepsin was confirmed by 3D fluorescence spectra and circular dichroism.     

Fluorometric probing on the binding of hematoxylin to serum albumin

The binding of a cell nucleus stain, hematoxylin (HTL), to bovine serum albumin (BSA) was studied by spectroscopy including fluorescence spectra, UV–Visible absorption, circular dichroism (CD) spectra, synchronous and three-dimensional fluorescence spectra. The results indicated that the binding had led to static fluorescence quenching, with non-radiation energy transfer happening within single molecule. The observed binding constant was calculated to be 10^5.588 l mol^?1 at 311 K and one binding site had formed. The thermodynamic parameters of the interaction complied with ΔG ^θ < 0, ΔH ^θ < 0, ΔS ^θ < 0 and the results indicate that hydrogen bonds played major role in the reaction. The distance r between donor (BSA) and acceptor (HTL) was obtained according to the Förster theory of non-radiation energy transfer. The structural change of BSA molecules with addition of HTL was analyzed and the optimized geometry of HTL–BSA was investigated by fluorescence probe method.     

Comparative analysis of prokaryotic diversity in solar salterns in eastern Anatolia (Turkey)

The prokaryotic communities of four salterns (Bingöl, Fadlum, Kemah, and Tuzlagözü) in Turkey were examined and compared using the cultivation and cultivation-independent methods [fluorescence in situ hybridization (FISH) and 454 pyrosequencing]. FISH analysis with universal probes revealed that feeding waters carried 1.6 × 10²–1.7 × 10³ cells mL^?1, while crystallization ponds carried 3.8 × 10⁶–2.0 × 10⁷ cells mL^?1 that were mostly haloarchaea, including square cells (except for Kemah). High-throughput 16S rRNA-based gene sequencing showed that the most frequent archaeal OTUs in Bingöl, Fadlum, Tuzlagözü, and Kemah samples were affiliated with Haloquadratum (76.8 %), Haloarcula (27.8 %), Halorubrum (49.6 %), and Halonotius (59.8 %), respectively. Bacteroidetes was the dominant bacterial phylum in Bingöl and Fadlum, representing 71.5 and 79.5 % of the bacterial OTUs (respectively), while the most abundant bacterial phylum found in the Kemah saltern was Proteobacteria (79.6 %). The majority of the bacterial OTUs recovered from Tuzlagözü belonged to the Cyanobacteria (35.7 %), Bacteroidetes (35.0 %), and Proteobacteria (25.5 %) phyla. Cultivation studies revealed that the archaeal isolates were closely related to the genera Halobacterium, Haloarcula, and Halorubrum. Bacterial isolates were confined to two phyla, Proteobacteria (Alphaproteobacteria and Gammaproteobacteria classes) and Bacteroidetes. Comparative analysis showed that members of the Euryarchaeota, Bacteroidetes, Proteobacteria, and Cyanobacteria phyla were major inhabitants of the solar salterns.     

Interactions of human serum albumin with bioactive 3<Emphasis Type="Italic">H</Emphasis>-imidazo[4,5-<Emphasis Type="Italic">a</Emphasis>]acridines: Insights from fluorescence spectroscopic studies

Several 3H-imidazo[4,5-a]acridine derivatives were conveniently synthesized by the reaction of imidazo[4,5-a]acridones in boiling POCl3. The imidazoacridones were obtained by rearrangement of 3H-imidazo[4',5':3,4]benzo[c]isoxazoles in concentrated sulfuric acid containing nitrous acid at room temperature. The structures of all newly synthesized compounds were confirmed by IR, ¹H NMR, and mass spectral data. The interactions of 3H-imidazo[4,5-a]acridines with human serum albumin (HSA) were studied by fluorescence spectroscopy. The binding of 3H-imidazo[4,5-a]acridines quenches the HSA fluorescence, revealing a 1: 1 interaction with a binding constant of about 2.34 × 10⁵–3.16 × 10⁶ M^–1. A decrease in fluorescence intensity at 339 nm, when excited at 280 nm, is attributed to changes in the environment of the protein fluorophores caused by the presence of the ligand. The differences in interactions of 3H-imidazo[4,5-a]acridines with HSA were observed using spectrofluorimetry technique.     

Toxin Gene Contents and Activity of <Emphasis Type="Italic">Bacillus thuringiensis</Emphasis> Strains Against Two Sugarcane Borer Species, <Emphasis Type="Italic">Diatraea saccharalis</Emphasis> (F.) and <Emphasis Type="Italic">D. flavipennella</Emphasis> (Box)

Bacillus thuringiensis (Berliner) bears essential characteristics in the control of insect pests, such as its unique mode of action, which confers specificity and selectivity. This study assessed cry gene contents from Bt strains and their entomotoxicity against Diatraea saccharalis (F.) and Diatraea flavipennella (Box) (Lepidoptera: Crambidae). Bioassays with Bt strains were performed against neonates to evaluate their lethal and sublethal activities and were further analyzed by PCR, using primers to identify toxin genes. For D. saccharalis and D. flavipennella, 16 and 18 strains showed over 30% larval mortality in the 7th day, respectively. The LC₅₀ values of strains for D. saccharalis varied from 0.08 × 10⁵ (LIIT-0105) to 4104 × 10⁵ (LIIT-2707) spores + crystals mL^?1. For D. flavipennella, the LC₅₀ values of strains varied from 0.40 × 10⁵ (LIIT-2707) to 542 × 10⁵ (LIIT-2109) spores + crystals mL^?1. For the LIIT-0105 strain, which was the most toxic to D. saccharalis, the genes cry1Aa, cry1Ab, cry1Ac, cry1B, cry1C, cry1D, cry1F, cry1I, cry2Aa, cry2Ab, cry8, and cry9C were detected, whereas for the strain LIIT-2707, which was the most toxic to D. flavipennella, detected genes were cry1Aa, cry1Ab, cry1Ac, cry1B, cry1D, cry1F, cry1I, cry2Aa, cry2Ab, and cry9. The toxicity data and toxin gene content in these strains of Bt suggest a great variability of activity with potential to be used in the development of novel biopesticides or as source of resistance genes that can be expressed in plants to control pests.     

Analysis of applicability of triplet-state emission of molecular hydrogen for spectral diagnostics of a DC discharge

The applicability of emission of the N ³Λ_σ triplet states of molecular hydrogen for spectral diagnostics of the positive column of a dc glow discharge in hydrogen at translational gas temperatures of 360–600 K, specific absorbed powers of 0.8–4.25 W/cm, gas pressures of p = 0.3–15.0 Torr, reduced fields of E/N = 30–130 Td, and electron densities of n _e = 4.0 × 10⁹–6.5 × 10¹⁰ cm^–3 is analyzed by using an advanced level-based semi-empirical collisional?radiative model. It is found that secondary processes make the main contribution to the population and decay of the N ³Λ_σ = a ³Σ⁺ _g , c ³Π _u , g ³Σ⁺ _g , h ³Σ⁺ _g , and i ³Π _g triplet states. The dipole-allowed transitions e ³Σ⁺ _g → a ³Σ⁺ _g , f ³Σ⁺ _g → a ³Σ⁺ _g , g ³Σ⁺ _g and k ³Π _u → a ³Σ⁺ _g can be used for spectral diagnostics of a dc discharge within a simplified coronal model.     

Fecundity of the tropical catadromous eels <Emphasis Type="Italic">Anguilla bicolor bicolor</Emphasis>, <Emphasis Type="Italic">A. bengalensis bengalensis</Emphasis> and <Emphasis Type="Italic">A. marmorata</Emphasis>

Maturation is one of the most important ontogenetic transitions in an individual’s life. However, the reproductive ecology of the tropical anguillid eel genus Anguilla at the onset of oceanic spawning migration is poorly understood. To understand the reproductive ecology, the fecundity of the tropical eels Anguilla bicolor bicolor, A. bengalensis bengalensis and A. marmorata was examined using advanced migrating silver eels (Stage IV and V). A close linear relationship was found between total length and fecundity in A. bengalensis bengalensis. The fecundities of A. bicolor bicolor (0.55 to 4.96 × 10⁶), A. bengalensis bengalensis (0.33–1.72 × 10⁶) and A. marmorata (0.99 × 10⁶) were within the range of those observed in temperate eels.     

Association of polymorphic markers of chemokine genes,their receptors,and <Emphasis Type="Italic">CD14</Emphasis> gene with coronary atherosclerosis

Atherosclerosis represents an inflammatory response to the disturbance of the endothelial layer in the arterial bloodstream. In the present study, an analysis of associations of polymorphic markers for the genes controlling synthesis of proteins involved in atherosclerosis pathogenesis in coronary atherosclerosis (CA) patients (217 subjects) and in a control group (250 subjects) was conducted. The following genes were examined: rs991804 (CCL2 gene), rs1126579 (CXCR2 gene), rs4074 (CXCL1 gene), rs4073 (CXCL8 gene), rs333 (CCR5 gene), rs2471859 (CXCR4 gene), rs1801157 (CXCL12 gene), and rs2569190 (CD14 gene). Using the Monte Carlo and Markov chain (APSampler) method, allele/genotype combinations associated with both low and high CA risk were revealed. The most important findings included the following: CXCR4*T/T + CCL2*C + CCR5*I/I (P_perm = 1 × 10^–6, OR = 0.44, 95% CI 0.3–0.63), CXCR2*C + CD14*C + CXCL12*G + CCL2*C + CCR5*D (P_perm = 4 × 10^–6, OR = 5.78, 95% CI 2.34–14.28), CD14*C + CCL2*C/C + CCR5*D (P_perm = 6.3 × 10^–6, OR = 5.81, 95% CI 2.17–15.56), CXCL8*A + CXCR2*C + CD14*T + CXCR4*C (P_perm = 0.01, OR = 3.21, 95% CI 1.63–6.31).     

Diversity of culturable bacterial communities in the intestinal tracts of goldfish (<Emphasis Type="Italic">Carassius auratus</Emphasis>) and their ability to produce <Emphasis Type="Italic">N</Emphasis>-acyl homoserine lactone

Intestinal bacteria isolated from goldfish (Carassius auratus) were identified based on 16 ribosomal RNA (rRNA) gene sequences and screened for their ability to produce N-acyl homoserine lactone (AHL), an autoinducer of the quorum sensing (QS) system. The 230 aerobes/facultative anaerobes that were isolated comprised members of the genera Aeromonas (184 isolates), Citrobacter (11), Enterobacter (2), Shewanella (28), Vagococcus (1), and Vibrio (4). Among these genera, the two most abundant species were Aeromonas veronii (163 isolates) and Shewanella xiamenensis (27). In addition, 142 obligate anaerobes consisting of Cetobacterium somerae (139 isolates), Clostridium frigidicarnis (2), and Cetobacterium sp. (1) were also isolated. One hundred seventy isolates (74.2%) belonging to the genera Aeromonas, Citrobacter, Enterobacter, Shewanella, and Vibrio produced AHL, while 155 (67.7%) and 91 (39.7%) isolates possessed the luxR and luxI gene homologs, respectively. None of the obligate anaerobes produced AHL or possessed luxRI homologs. Total viable counts ranged from 1.2 × 10⁷ to 2.2 × 10⁹ CFU/g, which were accounted for 0.8 to 15.2% of direct counts. Aeromonas veronii, S. xiamenensis, and C. somerae were detected from five goldfish at densities ranging from 4.0 × 10⁶ to 1.7 × 10⁹ CFU/g, indicating that these bacteria are dominant components of the culturable gut flora in goldfish. In addition, members of the genera Aeromonas and Shewanella appeared to communicate with each other by using the QS system to some extent when the concentration of AHL reaches a certain threshold. It is therefore suggested that bacteria with the ability to disrupt AHL secretion in intestinal environments are potential candidates for probionts for preventing opportunistic infections in freshwater fish such as goldfish.     

Detection and Quantification of <Emphasis Type="Italic">Vibrio cholerae,Vibrio parahaemolyticus</Emphasis>, <Emphasis Type="Italic">and Vibrio vulnificus</Emphasis> in Coastal Waters of Guinea-Bissau (West Africa)

V. cholerae, V. parahaemolyticus, and V. vulnificus are recognized human pathogens. Although several studies are available worldwide, both on environmental and clinical contexts, little is known about the ecology of these vibrios in African coastal waters. In this study, their co-occurrence and relationships to key environmental constraints in the coastal waters of Guinea-Bissau were examined using the most probable number-polymerase chain reaction (MPN-PCR) approach. All Vibrio species were universally detected showing higher concentrations by the end of the wet season. The abundance of V. cholerae (ISR 16S-23S rRNA) ranged 0–1.2 × 10⁴ MPN/L, whereas V. parahaemolyticus (toxR) varied from 47.9 to 1.2 × 10⁵ MPN/L. Although the presence of genotypes associated with virulence was found in environmental V. cholerae isolates, ctxA+ V. cholerae was detected, by MPN-PCR, only on two occasions. Enteropathogenic (tdh+ and trh+) V. parahaemolyticus were detected at concentrations up to 1.2 × 10³ MPN/L. V. vulnificus (vvhA) was detected simultaneously in all surveyed sites only at the end of the wet season, with maximum concentrations of 1.2 × 10⁵ MPN/L. Our results suggest that sea surface water temperature and salinity were the major environmental controls to all Vibrio species. This study represents the first detection and quantification of co-occurring Vibrio species in West African coastal waters, highlighting the potential health risk associated with the persistence of human pathogenic Vibrio species.     

Effect of entomopathogenic fungus <Emphasis Type="Italic">Metarhizium robertsii</Emphasis> on non-target organisms,water bugs (Heteroptera: Corixidae,Naucoridae, Notonectidae)

The influence of the fungus Metarhizium robertsii Bischoff, Rehner and Humber on the mortality of four water bug species, Cymatia coleoptrata (Fabricius), Sigara assimilis (Fieber), Ilyocoris cimicoides cimicoides (Linnaeus), and Notonecta reuteri Hungerford, and bloodsucking mosquito Anopheles messeae Falleroni, was investigated under various concentrations of conidia and different treatment types. We found that the mortality of adults of the water bug species was similar or higher than that of A. messeae, with C. coleoptrata and S. assimilis being more susceptible to M. robertsii than N. reuteri, I. c. cimicoides, and the mosquito A. messeae. Treatment with dry conidia at concentrations of 5 × 10⁴ and 5 × 10⁵ conidia/ml caused higher mortality of the water bug species than did treatment at the same concentrations with conidia in an aqueous suspension. In contrast, higher concentrations (5 × 10⁶ conidia/ml) led to higher mortality after treatment with the aqueous suspension, relative to treatment with dry conidia. Our studies showed that water bugs exhibited the classical development of a mycosis with hemocoel colonization, mummification, and conidia formation on cadavers directly on the surface of the water. Possible changes in invertebrate communities in aquatic ecosystems after treatment with Metarhizium are discussed.     

Abscisic Acid-Induced Starch Accumulation in Bioenergy Crop Duckweed <Emphasis Type="Italic">Spirodela polyrrhiza</Emphasis>

Spirodela polyrrhiza, a fast-growing duckweed with high starch and low lignin content, shows promise as a feedstock for bioenergy. Abscisic acid (ABA) is a biological hormone that controls plant growth and stress response. The effects of different ABA concentrations (0, 1.0 × 10^?5, 1.0 × 10^?4, 1.0 × 10^?3, 1.0 × 10^?2, and 1.0 × 10^?1 mg/L) on duckweed biomass growth, carbon dioxide fixation, formation of photosynthetic pigments (Chlorophyll a (Chla), Chlorophyll b (Chlb), and carotenoids), the activities of soluble starch synthase (SSS) and starch branching enzyme (SBE), and the starch content of biomass were investigated in this study. ABA at concentrations lower than 1.0 × 10^?3 mg/L promoted carbon dioxide fixation, whereas it inhibited carbon dioxide fixation at concentrations over 1.0 × 10^?3 mg/L. ABA enhanced SSS and SBE activities at concentrations lower than 1.0 × 10^?2 mg/L. ABA treatment increased the content of Chla, Chlb, and carotenoids and resulted in the enhancement of starch content. Chla content gradually increased with the increasing concentration of ABA (1.0 × 10^?5 to 1.0 × 10^?2 mg/L). After culturing for 10 days, starch content in 1.0 × 10^?2 mg/L ABA medium reached 35.3% of dry weight (DW), which was the highest level in this study. This suggests that there is a great potential to develop a technology to increase starch accumulation in duckweed which can be used as an alternative to corn, sugarcane, or other food crops as a starch source.     

Response of effective quantum yield of photosystem 2 to <Emphasis Type="Italic">in situ</Emphasis> temperature in three alpine plants

The response of effective quantum yield of photosystem 2 (ΔF/F_m’) to temperature was investigated under field conditions (1 950 m a.s.l.) in three alpine plant species with contrasting leaf temperature climates. The in situ temperature response did not follow an optimum curve but under saturating irradiances [PPFD >800 µìmol(photon) m^?2s^?1] highest ΔF/F_m’ occurred at leaf temperatures below 10°C. This was comparable to the temperature response of antarctic vascular plants. Leaf temperatures between 0 and 15°C were the most frequently (41 to 56%) experienced by the investigated species. At these temperatures, ΔF/F_m’ was highest in all species (data from all irradiation classes included) but the species differed in the temperature at which ΔF/F_m’ dropped below 50% (Soldanella pusilla >20°C, Loiseleuria procumbens >25°C, and Saxifraga paniculata >40°C). The in situ response of ΔF/F_m’ showed significantly higher ΔF/F_m’ values at saturating PPFD for the species growing in full sunlight (S. paniculata and L. procumbens) than for S. pusilla growing under more moderate PPFD. The effect of increasing PPFD on ΔF/F_m’, for a given leaf temperature, was most pronounced in S. pusilla. Despite the broad diurnal leaf temperature amplitude of alpine environments, only in S. paniculata did saturating PPFD occur over a broad range of leaf temperatures (43 K). In the other two species it was half of that (around 20 K). This indicates that the setting of environmental scenarios (leaf temperature×PPFD) in laboratory experiments often likely exceeds the actual environmental demand in the field.     

Cloning and Functional Analysis of <Emphasis Type="Italic">SaCLCc1</Emphasis>, a Gene Belonging to the Chloride Channel Family (<Emphasis Type="Italic">CLC</Emphasis>), from the Halophyte <Emphasis Type="Italic">Suaeda altissima</Emphasis> (L.) Pall.

One of the genes of the CLC (Chloride Channel) family, SaCLCc1, from the halophyte Suaeda altissima (L.) Pall. was cloned. To investigate the function of SaCLCc1, it was expressed in the S. cerevisiae deletion mutant Δgef1::LEU2 for the only gene of the CLC family in this organism. The growth of the transformed SaCLCc1-expressing mutant Δgef1 was restored when cells were grown in Fe²⁺-deficient YPEG medium, in minimal synthetic media SD and SR (pH 7.0), and in rich YPD medium containing Mn²⁺. The complementation of the Δgef1 mutant phenotype with the SaClCc1 gene indicates the involvement of the SaClCc1 protein in the transport of Cl^– ions.     

Community and hospital acquired methicillin resistant <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> efficiently retain the <Emphasis Type="Italic">Van A</Emphasis> determinant

Dissemination of vancomycin resistance from hospital to community strains is a serious threat to public health. Our study aimed to provide evidence for transmission of Van A type resistance from the hospital to the community. Wild-type community and hospital associated methicillin resistant Staphylococcus aureus strains were studied in vitro and in a model that mimicked a natural environment to ascertain their ability to acquire and maintain the vancomycin resistance determinant (Van A gene) from vancomycin resistant Enterococcus faecalis. Fitness was assessed and the cost of Van A acquisition and retention was estimated. In vitro mating experiments were carried out using a filter mating technique and a model of a natural water body environment. Transfer of resistance was carried out in two different conditions: restricted and favorable. Transconjugants were confirmed by E test and PCR using specific primer sets. Growth kinetics and fitness measurements were done by spectrometric analysis. Using the in vitro filter mating technique, high transfer frequencies that ranged from 0.7 × 10^–3(0.0006) to 3.1 × 10^–4(0.00011) were recorded, with the highest transfer frequencies for CA MRSA (thermosensitively homogenous) (0.7 × 10^–3), and 1.2 × 10^–4 to 2.4 × 10^–6 in the model. HA MRSA (homogenous) showed a greater capacity (3.6 × 10^–4) to receive the Van A gene, while CA MRSA showed a reduced ability to maintain the gene after serial subcultures. CA and HA thermosensitively heterogeneous MRSA transconjugants exhibited higher growth rates. The present study provides evidence for the enhanced ability of CA and HA MRSA clones to acquire and maintain Van A type resistance.     

Multi-locus phylogeny and morphology reveal five new species of <Emphasis Type="Italic">Fomitiporia</Emphasis> (Hymenochaetaceae) from China

Five newly identified species of Fomitiporia (F. alpina, F. gaoligongensis, F. hainaniana, F. subrobusta and F. subtropica) and their morphological and molecular characterisation are described in this paper. Fomitiporia alpina sp. nov. is distinguished by its pileate basidiomata, parallel tramal hyphae and large basidiospores (6.5–8 × 6–8 μm), and by its gymnosperm wood-living habitat. Fomitiporia gaoligongensis sp. nov. is distinct from other species due to its semicircular pileus and subglobose to globose basidiospores (6.5–7.6 × 6–7.4 μm). Fomitiporia hainaniana sp. nov. is marked by its resupinate basidiomata, the presence of setae and small globose basidiospores (4–5 × 3.8–4.4 μm). Fomitiporia subrobusta sp. nov. is characterised by its triquetrous basidiomata, small pores (6–9 per mm) with entire and thick dissepiments, and subglobose to obovoid basidiospores (6.2–6.8 × 5.2–6 μm). Fomitiporia subtropica sp. nov. can be differentiated by its resupinate basidiomata, smaller pores (6–10 per mm) and smaller basidiospores (5.2–6 × 4.4–5 μm). Phylogenetic analysis, based on multi-gene comparison of the internal transcribed spacer regions (ITS), nuclear large subunit ribosomal RNA gene regions (nLSU), the translation elongation factor 1-α gene (tef1α) and the second subunit of RNA polymerase II (rpb2), confirmed affinity with the Fomitiporia species and showed association with similar fungi in the genus.     

Yeast population of the Kindo Peninsula lichens

Yeast abundance and species diversity in the lichens collected at the Kindo Peninsula (Karelia) were studied. A total of 14 lichen species analyzed belonged to the genera Bryoria, Cladonia, Hypogymnia, Icmadophila, Nephroma, Peltigera, and Ramalina. Abundance of cultured yeasts in lichens was intermediate between soil and phyllosphere. The average yeast number on lichens was ~2.5 × 10³ CFU/g, while it exceeded 8 × 10³ CFU/g on plants and reached only 1 × 10³ CFU/g in soil. Yeast population of different parts of Cladonia lichens was found to vary significantly in abundance, species diversity, and community structure. The highest yeast abundance and diversity were revealed in the growth zone. Fifteen yeast species were isolated from lichens, including 6 basidiomycetous and 9 ascomycetous ones. Unlike soils and plants, yeast population of lichens consisted mainly of ascomycetous species, with predominance of Candida sphagnicola and anamorphous yeasts of the genus Dothiora. These results show that yeasts from different taxonomic and ecological groups are a necessary component of lichens; conditions favoring the preservation and development of specific yeast communities differing from the typical soil and phyllosphere yeast complexes are formed in the lichens of northern taiga forests.     

Hardness maximization or equalization? New insights and quantitative relations between hardness increase and bond dissociation energy

It has been overlooked that the change of hardness, η, upon bonding is intimately connected to thermochemical cycles, which determine whether hardness is increased according to Pearson’s “maximum hardness principle” (MHP) or equalized, as expected by Datta’s “hardness equalization principle” (HEP). So far the performances of these likely incompatible “structural principles” have not been compared. Computational validations have been inconclusive because the hardness values and even their qualitative trends change drastically and unsystematically at different levels of theory. Here I elucidate the physical basis of both rules, and shed new light on them from an elementary experimental source. The difference, Δη = η _mol – <η _at>, of the molecular hardness, η _mol, and the averaged atomic hardness, <η _at>, is determined by thermochemical cycles involving the bond dissociation energies D of the molecule, D ⁺ of its cation, and D ^? of its anion. Whether the hardness is increased, equalized or even reduced is strongly influenced by ΔD = 2D – D ⁺  ? D ^?. Quantitative expressions for Δη are obtained, and the principles are tested on 90 molecules and the association reactions forming them. The Wigner-Witmer symmetry constraints on bonding require the valence state (VS) hardness, η _VS, instead of the conventional ground state (GS) hardness, η _GS. Many intriguingly “unpredictable” failures and systematic shortcomings of said “principles” are understood and overcome for the first time, including failures involving exotic and/or challenging molecules, such as Be_2, B₂, O₃, and transition metal compounds. New linear relationships are discovered between the MHP hardness increase Δη _VS and the intrinsic bond dissociation energy D _i . For bond formations, MHP and HEP are not compatible, and HEP does not qualify as an ordering rule.     

Effects of Exogenous Phytohormones on Spore Germination and Morphogenesis of <Emphasis Type="Italic">Polystichum aculeatum</Emphasis> (L.) Roth Gametophyte in vitro Culture

The effects of exogenous phytohormones–gibberellic acid (GA3) and benzyl-aminopurine (BAP)–on the spore germination and morphogenesis of Polystichum aculeatum (L.) Roth gametophyte in vitro culture were studied. In the control, four stages of gametophyte morphogenesis were determined and their periods were established. Spore germination and protonema formation of P. aculeatum occurred according to the Vittaria-type and prothalium development according to the Aspidium-type. The spore germination percentage depended on the storage time duration. It was found that 80–95% of freshly collected spores germinated. Spore viability was within the range of 68–95% after 4–6-month storage under lab conditions and did not exceed 20% after 1.5 year of the storage period. High concentrations of exogenous GA3 (10^–5 and 10^–6 M) and BAP (10–5 M) significantly inhibited spore germination, whereas low concentrations (GA3 10^–7–10^–8 M) had an insignificant stimulating effect or did not affect germination at all (BAP 10^–6, 10^–7, 10^–8 M). All concentrations of exogenous BAP were demonstrated to inhibit the development of P. aculeatum gametophyte at the protonema stage, which might be due to the removal of apical dominance. The inhibiting effect directly depended on BAP concentrations. The formation of abnormal thalli of the P. aculeatum gametophyte in the response to exogenous GA3 treatments occurred as a result of impairment of cell growth by elongation. A direct interrelationship between GA3 concentrations and level of morphological abnormalities and grade of thalli underdevelopment was demonstrated.