Secondary structure of globulins from plant seeds: a re-evaluation from circular dichroism measurements

The secondary structure parameters of plant seed globulins (11S from Brassica napus L, 11S from Helianthus annuus L, IIS from Vicia faba, 7S from Phaseolus vulgaris L) have been determined from their circular dichroism spectra by the method of Provencher and Glöckner. According to this method, the proteins contain 40–50% β-sheet structure and only about 10% helical structure. We conclude, therefore, that the plant seed globulins belong to the class of β-sheet proteins. Their overall secondary structure is homologous. It is shown that the method of Provencher and Glöckner provides reasonable secondary structure parameters for proteins which are rich in β-sheet structure even if the spectral range utilized for analysis is restricted to 210–240 nm.     

7S Globulins from Phaseolus vulgaris L.: Impact of Structural Aspects on the Nutritional Quality

7S globulins were extracted from common bean (Phaseolus vulgaris L.) seeds and characterized. SDS–PAGE showed major bands corresponding to the phaseolin subunits (43–53 kDa). An amino acid analysis indicated that, in spite of the limited amounts of sulphur amino acids and tryptophan, the globulins contained very high levels of essential amino acids. The protein solubility profiles of native and denatured (120 °C for 20 min) 7S globulins in water and in 0.5 M NaCl showed that NaCl had a limited effect on increasing the solubility of either the native or denatured proteins. The in vivo small intestinal digestibility of the 7S globulins was 90%, this being decreased to 86% after a thermal treatment. Fourier transform infrared spectroscopy revealed a high content of β-sheet and β-turn structures, together with a contribution at 1687 cm^?1 that was assigned to intramolecular β-sheets. These features are diagnostic of a high propensity to irreversible aggregation that may be related to an adverse effect on the protein quality.     

Toxic and non-toxic strains of Microcystis aeruginosa induce temperature dependent allelopathy toward growth and photosynthesis of Chlorella vulgaris

Global warming was believed to accelerate the expansion of cyanobacterial blooms. However, the impact of changes due to the allelopathic effects of cyanobacterial blooms with or without algal toxin production on the ecophysiology of its coexisting phytoplankton species arising from global warming were unknown until recently. In this study, the allelopathic effects of toxic and non-toxic Microcystis aeruginosa strains on the growth of green alga Chlorella vulgaris and photosynthesis of the co-cultivations of C. vulgaris and toxic M. aeruginosa FACHB-905 or non-toxic M. aeruginosa FACHB-469 were investigated at different temperatures. The growth of C. vulgaris, co-cultured with the toxic or non-toxic M. aeruginosa strains, was promoted at 20 °C but inhibited at temperatures ≥25 °C. The inhibitory effects of the toxic and non-toxic M. aeruginosa strains on of the co-cultivations (C. vulgaris and non-toxic M. aeruginosa FACHB-469 or toxic M. aeruginosa FACHB-905) also linearly increased with elevated temperatures. Furthermore, toxic M. aeruginosa FACHB-905 induced more inhibition toward growth of C. vulgaris or P_max and R_d of the mixtures than non-toxic M. aeruginosa FACHB-469. C. vulgaris dominated over non-toxic M. aeruginosa FACHB-469 but toxic M. aeruginosa FACHB-905 overcame C. vulgaris when they were co-cultured in mesocosms in water temperatures from 20 to 25 °C. The results indicate that allelopathic effects of M. aeruginosa strains on C. vulgaris are both temperature- and species-dependent: it was stimulative for C. vulgaris at low temperatures such as 20 °C, but inhibitory at high temperatures (≥25 °C); the toxic strain was determined to be more harmful to C. vulgaris than the non-toxic one. This suggests that global warming may aggravate the ecological risk of cyanobacteria blooms, especially those with toxic species as the main contributors.     

Identifying new sex-linked genes through BAC sequencing in the dioecious plant Silene latifolia

Background

Silene latifolia represents one of the best-studied plant sex chromosome systems. A new approach using RNA-seq data has recently identified hundreds of new sex-linked genes in this species. However, this approach is expected to miss genes that are either not expressed or are expressed at low levels in the tissue(s) used for RNA-seq. Therefore other independent approaches are needed to discover such sex-linked genes.

Results

Here we used 10 well-characterized S. latifolia sex-linked genes and their homologs in Silene vulgaris, a species without sex chromosomes, to screen BAC libraries of both species. We isolated and sequenced 4 Mb of BAC clones of S. latifolia X and Y and S. vulgaris genomic regions, which yielded 59 new sex-linked genes (with S. vulgaris homologs for some of them). We assembled sequences that we believe represent the tip of the Xq arm. These sequences are clearly not pseudoautosomal, so we infer that the S. latifolia X has a single pseudoautosomal region (PAR) on the Xp arm. The estimated mean gene density in X BACs is 2.2 times lower than that in S. vulgaris BACs, agreeing with the genome size difference between these species. Gene density was estimated to be extremely low in the Y BAC clones. We compared our BAC-located genes with the sex-linked genes identified in previous RNA-seq studies, and found that about half of them (those with low expression in flower buds) were not identified as sex-linked in previous RNA-seq studies. We compiled a set of ~70 validated X/Y genes and X-hemizygous genes (without Y copies) from the literature, and used these genes to show that X-hemizygous genes have a higher probability of being undetected by the RNA-seq approach, compared with X/Y genes; we used this to estimate that about 30 % of our BAC-located genes must be X-hemizygous. The estimate is similar when we use BAC-located genes that have S. vulgaris homologs, which excludes genes that were gained by the X chromosome.

Conclusions

Our BAC sequencing identified 59 new sex-linked genes, and our analysis of these BAC-located genes, in combination with RNA-seq data suggests that gene losses from the S. latifolia Y chromosome could be as high as 30 %, higher than previous estimates of 10-20 %.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1698-7) contains supplementary material, which is available to authorized users.     

Temperature Effects on Development of Meloidogyne Enterolobii and M. Floridensis

Meloidogyne enterolobii and M. floridensis are virulent species that can overcome root-knot nematode resistance in economically important crops. Our objectives were to determine the effects of temperature on the infectivity of second-stage juveniles (J2) of these two species and determine differences in duration and thermal-time requirements (degree-days [DD]) to complete their developmental cycle. Florida isolates of M. enterolobii and M. floridensis were compared to M. incognita race 3. Tomato cv. BHN 589 seedlings following inoculation were placed in growth chambers set at constant temperatures of 25°C, and 30°C, and alternating temperatures of 30°C to 25°C (day–night). Root infection by the three nematode species was higher at 30°C than at 25°C, and intermediate at 30°C to 25°C, with 33%, 15%, and 24% infection rates, respectively. There was no difference, however, in the percentages of J2 that infected roots among species at each temperature. Developmental time from infective J2 to reproductive stage for the three species was shorter at 30°C than at 25°C, and 30°C to 25°C. The shortest time and DD to egg production for the three species were 13 days after inoculation (DAI) and 285.7 DD, respectively. During the experimental timeframe of 29 d, a single generation was completed at 30°C for all three species, whereas only M. floridensis completed a generation at 30°C to 25°C. The number of days and accumulated DD for completing the life cycle (from J2 to J2) were 23 d and 506.9 DD for M. enterolobii, and 25 d and 552.3 DD for M. floridensis and M. incognita, respectively. Exposure to lower (25°C) and intermediate temperatures (30°C to 25°C) decreased root penetration and slowed the developmental cycle of M. enterolobii and M. floridensis compared with 30°C.     

Cucurbitane-type triterpenoids from the aerial parts of Momordica charantia L.

Six new cucurbitane-type triterpenoids (1–6), together with two known analogues (7 and 8) were isolated from the aerial parts of Momordica charantia L. The structures of new compounds were identified as cucurbita-6,24-dien-3β,23-diol-19,5β-olide (1), (19R)-5β,19-epoxy-19-methoxycucurbita-6,24-dien-3β,23-diol (2), (19S)-5β,19-epoxy-19-methoxycucurbita-6,24-dien-3β,23-diol (3), (19R)-5β,19-epoxy-19-isopropoxycucurbita-6,24-dien-3β,23-diol (4), 3β,23-dihydroxy-5-methoxycucurbita-6,24-dien-19-al (5) and (19R)-7β,19-epoxy-19-methoxycucurbita-5,24-dien-3β,23-diol (6), by extensive MS, 1D and 2D NMR spectroscopic technologies. This is the first report of the isolation of tetracyclic triterpenoids possessing a 7β,19-epoxy system, viz., 6, from M. charantia L.     

Above- and below-ground competition effects of two heathland species: Implications for growth and response to herbivory in birch saplings

We examined experimentally the effect of competition from Calluna vulgaris or Molinia caerulea on Betula pubescens saplings subjected to simulated mammalian browsing damage. We tested three hypotheses: 1. that responses to competition will follow the balanced growth hypothesis with the predominant competition effect being below-ground, resulting in increased allocation to roots; 2. that above-ground competition effects from C. vulgaris are greater than M. caerulea, resulting in differences in growth allocation; 3. that, when only B. pubescens saplings are damaged, herbivory reduces its ability to compete with both species.We grew B. pubescens saplings in the presence of below- or above- and below-ground interactions from C. vulgaris or M. caerulea. Saplings were also subjected to simulated browsing by clipping (50% of current year's growth), either pre-senescence or at bud-burst. We measured the morphology and dry mass allocation response of the saplings one year after the browsing was applied.Competition reduced sapling dry mass by approximately 50%, but C. vulgaris reduced dry mass to a greater extent than M. caerulea. This difference was due to a smaller impact of M. caerulea shoots than C. vulgaris shoots on birch growth. Saplings compensated for browsing damage, resulting in no difference in dry mass one year after damage. However, sapling morphological responses to browsing damage were dependent on the competing species.Despite the large competitive effect of below-ground interactions, saplings did not increase allocation to root growth as predicted. Additionally, in response to above-ground interactions from M. caeruela, saplings increased allocation to root growth relative to those growing with C. vulgaris. As such, growth responses to competition were not explained by the balanced growth hypothesis.This study highlights the importance of patterns, as well as intensity, of competition in determining plant responses to inter-specific interactions.     

Fatty acid changes during maturation of Momordica charantia and Trichosanthes Anguina Seeds

Changes in fatty acids were studied during maturation of Momordica charantia and Trichosanthes anguina seeds, which contain cis-9, trans-11, trans-13-octadecatrienoic acid (α-eleostearic) and cis-9, trans-11, cis-13-octadecatrienoic acid (punicic), respectively. The two seeds matured 30 and 35 days after flowering, respectively. Total lipids as well as α-eleostearic acid accumulated rapidly from 10 to 20 days in M. charantia. In T. anguina the active period of lipid synthesis was from 15 to 30 days but punicic acid continued to be synthesized until maturity. In both species, the disappearance of linolenic acid and the reduction in concentration of linoleic acid were concomitant with the formation of conjugated fatty acids. The conjugated fatty acids were absent from monoacylglycerols and phospholipids of both species, and also from the diacylglycerols of M. charantia, throughout maturation     

Phylogeography of a widely distributed plant species reveals cryptic genetic lineages with parallel phenotypic responses to warming and drought conditions

To predict how widely distributed species will perform under future climate change, it is crucial to understand and reveal their underlying phylogenetics. However, detailed information about plant adaptation and its genetic basis and history remains scarce and especially widely distributed species receive little attention despite their putatively high adaptability.To examine the adaptation potential of a widely distributed species, we sampled the model plant Silene vulgaris across Europe. In a greenhouse experiment, we exposed the offspring of these populations to a climate change scenario for central Europe and revealed the population structure through whole‐genome sequencing. Plants were grown under two temperatures (18°C and 21°C) and three precipitation regimes (65, 75, and 90 mm) to measure their response in biomass and fecundity‐related traits. To reveal the population genetic structure, ddRAD sequencing was employed for a whole‐genome approach. We found three major genetic clusters in S. vulgaris from Europe: one cluster comprising Southern European populations, one cluster of Western European populations, and another cluster containing central European populations. Population genetic diversity decreased with increasing latitude, and a Mantel test revealed significant correlations between F _ST and geographic distances as well as between genetic and environmental distances. Our trait analysis showed that the genetic clusters significantly differed in biomass‐related traits and in the days to flowering. However, half of the traits showed parallel response patterns to the experimental climate change scenario. Due to the differentiated but parallel response patterns, we assume that phenotypic plasticity plays an important role for the adaptation of the widely distributed species S. vulgaris and its intraspecific genetic lineages.     

THE PIGMENT-PROTEIN COMPOUND IN PHOTOSYNTHETIC BACTERIA : II. THE ABSORPTION CURVES OF PHOTOSYNTHIN FROM SEVERAL SPECIES OF BACTERIA

Absorption curves have been obtained in the spectral region of 450 to 900 mµ for the water soluble cell juice of four species of photosynthetic bacteria, Spirillum rubrum (strain S1), Rhodovibrio sp. (strain Gaffron), Phaeomonas sp. (strain Delft), and Streptococcus varians (strains C11 and orig.). These curves all show maxima at 790 and 590 mµ due to bacteriochlorophyll, whose highest band, however, occurs at 875, 855, or 840 mµ depending on the species. The bacteria that appear red rather than brown have a band at 550 mµ due to a carotinoid pigment. An absolute absorption curve of bacteriophaeophytin has maxima at 530 and 750 mµ. The extraction of cell juice by supersonic vibration does not change the position of the absorption bands or of the light absorbing capacity of the pigment.     

Temperature Effects on Mitochondrial Respiration in Phaseolus acutifolius A. Gray and Phaseolus vulgaris L

Electron transport, using succinate as a substrate, was measured polarographically in mitochondria isolated from Phaseolus vulgaris and P. acutifolius plants at 25°C and 32°C. Mitochondria isolated from P. vulgaris plants grown at 32°C had reduced electron transport and were substantially uncoupled. Growth at 32°C had no effect on electron transport or oxidative phosphorylation in P. acutifolius compared to 25°C grown plants. Mitochondria isolated from 25°C grown P. vulgaris plants measured at 42°C were completely uncoupled. Similarly treated P. acutifolius mitochondria remained coupled. The uncoupling of P. vulgaris was due to increased proton permeability of inner mitochondrial membrane. The alternative pathway was more sensitive to heat than the regular cytochrome pathway. At 42°C, no alternative pathway activity was detected. The substantially greater heat tolerance of P. acutifollus compared to P. vulgaris mitochondrial electron transport suggests that mitochondrial sensitivity to elevated temperatures is a major limitation to growth of P. vulgaris at high temperatures and is an important characteristic conveying tolerance in P. acutifolius.     

Blockade of heavy metals accumulation in Chlorella vulgaris cells by 24-epibrassinolide

This study was conducted on the influence of 24-epibrassinolide (24-epiBL) mixed with varying concentrations of heavy metals (copper, lead, cadmium, zinc) upon the growth and accumulation of these heavy metals in the cell of the alga Chlorella vulgaris Beijerinck (Chlorophyceae). Heavy metals at the concentration of 10^–3 M, alone or mixed with 24-epiBL, showed a lethal effect on C. vulgaris. At metal concentrations of 10^–6–10^–4 M, a combination with 24-epiBL appeared to have a stronger stimulatory effect on a number of cells than a single metal (a stronger inhibitory effect). 24-EpiBL at the concentration of 10^–8 M in combination with heavy metals (in the range 10^–6–10^–4 M) blocked metal accumulation in algal cells. 24-EpiBL has an anti-stress effect on C. vulgaris contaminated by heavy metals. The inhibitory effect on metal accumulation of 24-epiBL mixed with different heavy metals was arranged in the following order: zinc > cadmium > lead > copper. This process is correlated with the stimulation of growth of C. vulgaris. The stimulatory effect of 24-epiBL mixed with heavy metals leading to an increased pH in the medium (5.28–6.20) was significantly higher than the impact due to the increased acidity in the medium due to metals alone (pH 3.10–5.85). Lower pH increased the toxicity of heavy metals in C. vulgaris cells.     

Green synthesis of zero valent colloidal nanosilver targeting A549 lung cancer cell: In vitro cytotoxicity

An eco-friendly green approach was proposed to synthesise stable, cytotoxic colloidal silver nanoparticles (AgNPs) using Momordica charantia (M. charantia) fruit extract. Bioinspired green method adopted for fabrication of AgNPs because of easy, fast, low-cost and benign bioprocess. Phytocomponents played the crucial role in capping, stabilisation and inherent cytotoxic potential of colloidal nanosilver. The physiochemical, crystalline, optical and morphological properties of AgNPs were characterized using UV-vis, FT-IR, XRD, SEM, TEM, EDX and AFM. FT-IR reveals the presence of carbonyl, methyl, polyphenol (flavonoid), primary and secondary amine (protein), carboxyl group, ester as major functional groups over the surface of nanomaterials. Mechanistic pathway for formation and stabilisation of colloidal nanosilver has been discussed. Average crystalline size of AgNPs was found to be 12.55?nm from XRD. TEM shows AgNPs nanosphere with size range 1–13.85?nm. Consistency in spherical morphology was also confirmed through Atomic Force Microscopy (AFM). AFM measurement provided image Rq value 3.62, image Ra 2.47, roughness Rmax 36.4?nm, skewness 1.99 and kurtosis 9.87. The SRB assay revealed substantial in vitro noticeable anti-cancer activity of colloidal nanosilver on A549 and HOP-62 human lung cancer cells in a dose dependent manner with IC50 value of 51.93?µg/ml and 76.92?µg/ml. In addition, M. charantia capped AgNPs were found to be more biocompatible in comparison to M. charantia FE. Our study demonstrated the integration of green chemistry principle in nanomaterials fabrication and focused on the potential use of M. charantia fruit extract as an efficient precursor for biocompatible AgNPs anodrug formulation with improved cytotoxic applications.     

Temperature Affects Species Distribution in Symbiotic Populations of Vibrio spp.

The genus Sepiola (Cephalopoda: Sepiolidae) contains 10 known species that occur in the Mediterranean Sea today. All Sepiola species have a light organ that contains at least one of two species of luminous bacteria, Vibrio fischeri and Vibrio logei. The two Vibrio species coexist in at least four Sepiola species (S. affinis, S. intermedia, S. ligulata, and S. robusta), and their concentrations in the light organ depend on changes in certain abiotic factors, including temperature. Strains of V. fischeri grew faster in vitro and in Sepiola juveniles when they were incubated at 26°C. In contrast, strains of V. logei grew faster at 18°C in culture and in Sepiola juveniles. When aposymbiotic S. affinis or S. ligulata juveniles were inoculated with one Vibrio species, all strains of V. fischeri and V. logei were capable of infecting both squid species at the optimum growth temperatures, regardless of the squid host from which the bacteria were initially isolated. However, when two different strains of V. fischeri and V. logei were placed in direct competition with each other at either 18 or 26°C, strains of V. fischeri were present in sepiolid light organs in greater concentrations at 26°C, whereas strains of V. logei were present in greater concentrations at 18°C. In addition to the competition experiments, the ratios of the two bacterial species in adult Sepiola specimens caught throughout the season at various depths differed, and these differences were correlated with the temperature in the surrounding environment. My findings contribute additional data concerning the ecological and environmental factors that affect host-symbiont recognition and may provide insight into the evolution of animal-bacterium specificity.     

Relationship between phytoplankton and environmental factors in landscape water supplemented with reclaimed water

The water quality of Feng-qing Lake, which is a landscape lake supplemented with reclaimed water, was surveyed to investigate the relationship between phytoplankton and environmental variables. A total of 29 water samples were collected to analyze temporal variations of phytoplankton and environmental factors from July 2013 to June 2014. Six phyla and 39 genera of phytoplankton were identified when the lake was supplied with reclaimed water. Among these, Cyanophyta and Chlorophyta account for 38.46% and 30.77% of phytoplankton, respectively. The dominant species in the lake are Pseudanabaena limnetica and Chlorella vulgaris, which are present the entire year. Other leading species include Cosmarium sp. and Raphidiopsis curvata. Principal component analysis (PCA) was conducted to analyze the relationship among environmental factors. Canonical correspondence analysis (CCA) was performed to investigate the relationship between environment factors and dominant species. The PCA result showed that temperature (T), total phosphorus (TP), total nitrogen (TN), transparency, and dissolved oxygen are the main factors that affect the eutrophication level of the lake. The CCA result revealed that TN, PO₄³⁻–P, chemical oxygen demand (COD), T, and chlorophyll a exhibit a close relation with dominant species. In particular, TN, salinity, and COD influence the growth of P. limnetica; T and COD influence the growth of R. curvata; and T, PO₄³⁻–P, NH₃–N, and pH influence the growth of C. vulgaris and Cosmarium sp.     

Effect of mixed diets (cyanobacteria and green algae) on the population growth of the cladocerans <Emphasis Type="Italic">Ceriodaphnia dubia</Emphasis> and <Emphasis Type="Italic">Moina macrocopa</Emphasis>

Microcystis aeruginosa, a cosmopolitan form, is a colonial cyanobacterium, which is also common in many freshwater bodies in Mexico. In eutrophic water bodies cyanobacteria are often the main phytoplankton that co-exist with cladocerans. We evaluated the effect of mixed diets, comprising 0, 25, 50, 75, and 100% on dry weight basis of M. aeruginosa, and the rest of one of two green algal species (Chlorella vulgaris and Scenedesmus acutus), on the population growth of the cladocerans Ceriodaphnia dubia and Moina macrocopa. Regardless of the share of M. aeruginosa in the mixed diet, C. dubia fed Chlorella had a longer initial lag phase. However, in mixed diet with S. acutus, the lag phase of C. dubia increased with increasing proportion of M. aeruginosa. When raised on 100% M. aeruginosa, the population growth of C. dubia was lowered compared with 100% S. acutus or 100% C. vulgaris. Increased proportion of M. aeruginosa in the mixed diet also resulted in decreased abundance of M. macrocopa. Irrespective of diet type, M. macrocopa had a shorter lag phase than C. dubia. Depending on the diet type, the rate of population increase (r) of C. dubia varied from 0.07 to 0.26 d⁻¹ while that of M. macrocopa was higher (0.14–0.61 d⁻¹). For both cladoceran species, the lower r values were obtained when fed Microcystis. Our study showed that the strain of M. aeruginosa was not highly toxic to cause total elimination of either C. dubia or M. macrocopa. Addition of a green algal component to the diet improved the population growth rates of both cladoceran species.     

Formation of carbon monoxide and bile pigment in red and blue-green algae

Chromium was not required for normal growth of romaine lettuce (Lactuca sativa L. subsp. longifolia), tomato (Lycopersicon esculentum Mill.), wheat (Triticum aestivum L.), or bean (Phaseolus vulgaris L.) in solution culture containing 3.8 × 10⁻⁴ μM Cr. Plants grown on this purified nutrient solution contained an average of 22 ng Cr/g dry weight. Duckweed (Lemna sp.) grew and reproduced normally on a dilute nutrient solution containing 3.8 × 10⁻⁵ μM Cr.     

Phylogeography and genetic diversity of the red squirrel (Sciurus vulgaris) in China: Implications for the species' postglacial expansion history

The geographical distribution of Sciurus vulgaris spans much of the Palearctic from western Europe and the UK eastward to the pacific coast of East Asia. S. vulgaris occurs in China only in the far northwest and the northeast. Understanding of the species’ postglacial expansion history in East Asia has been limited by the paucity of molecular data. In this study, we used partial D-loop and cytochrome b gene sequences to assess mitochondrial DNA variation in S. vulgaris in China. Our objectives were to (1) determine phylogeographical patterns of S. vulgaris in China; (2) understand the species’ postglacial expansion history in this region; and (3) quantify genetic diversity levels within S. vulgaris populations in China. We identified a supported phylogenetic group in S. vulgaris from China, and found no tendency for haplotypes to cluster by geographic region. Our analysis of S. vulgaris from China and other regions supports the hypothesis that the Calabria region of southern Italy is a glacial refugium for the species. We tentatively propose a postglacial expansion pattern for the squirrels: migrating from Calabria via Central and Eastern Europe to Russia and from there to China, and firstly to the northwest and then to northeast in China. We found high levels of genetic diversity in S. vulgaris populations across China as a whole, and discussed its influential factors.