Antimicrobic and hemolytic activity of low-molecular metabolits of brown seaweed <Emphasis Type="Italic">Laminaria cichorioides</Emphasis> (Miyabe)

Antimicrobial and hemolytic activity of ethanol extract of brown seaweed Laminaria cichorioides (Miyabe), its lipophilic fractions, various classes of substances of lipophilic fraction, such as chlorophylls, fucoxanthin, monogalactosyldiacylglycerols, digalactosyldiacylglycerols, sulfoquinovosyldiacylglycerols, and fatty acids were investigated. The antimicrobial activity was studied by means of yeast cells Safale S-04 and Candida albicans KMM 455, fungi Aspergillus niger KMM 4634 and Fusarium oxysporum KMM 4639, bacteria Staphylococcus aureus ATCC 21027 (gram-positive) and Escherichia coli ATCC 15034 (gram-negative) which demonstrated selective sensitivity to the studied substances. Hemolytic activity was investigated at concentrations of substances in the range of 0.2–200 μg/ml at different pH of erythrocyte suspension. All investigated substances caused hemolysis. The dependence of hemolytic activity of substances on pH of media was determined.     

Optimal strategy of plant antiherbivore defense: Implications for apparency and resource-availability theories

Plants produce chemicals as methods against animal herbivory. Such chemical defenses are classified into two major categories: (i) quantitative defenses with massive production of indigestible substances; and (ii) qualitative defenses with production of poisonous substances. A mathematical model was developed that identified factors that favored the evolution of quantitative defenses. Selecting an annual plant for simplicity, the allocation of photosynthetic production between growth substances and defense substances was considered. If the plant invests more in defense substances, it can protect itself more efficiently from herbivory but with a reduced growth rate. If it invests more in growth substances, the contrary holds. Using Pontoryagin's maximum principle, the following results were obtained: (i) the plant should conduct quantitative defenses when the growth rate (G), reflecting resource-availability, is low and the growth period (T) is long as well; (ii) if the plant invests in quantitative defenses, the optimal proportion of defense substances (χ^*) should be higher asG is smaller, but it is independent ofT; and (iii) the value of χ^* is not monotone for the effectiveness of defense substance (A), but has a maximum at an intermediate value ofA. Predictions of the model partly supported both Feeny's apparency theory, claiming that apparent plants or their parts for herbivores should quantitatively defend themselves, and Coley's resource-availability theory, claiming that plants with rich resources should invest in growth rather than defense.     

How Specific are Host-Produced Kairomones to Host-Seeking Ixodid Ticks?

Ixodid ticks respond to host-produced substances (kairomones) that influence the ticks’ host-finding behavior. In the laboratory adult blacklegged ticks, Ixodes scapularis Say, lone star ticks, Amblyomma americanum L., and American dog ticks, Dermacentor variabilis (Say) became akinetic on residues rubbed from their principal hosts (deer for the former two species and dogs for the latter). However, arrestment also occurred when adults of these species were tested using the same method bioassay, but with host substances reversed (i.e., I. scapularis and A. americanum against canine substances, and D. variabilis against deer gland substances). Although adult D. variabilis exhibited arrestant responses to deer substances and are often found along trails used by deer, they apparently make little use of deer as hosts. It is unclear whether responding to deer-produced kairomones may have disadvantages for D. variabilis. Until the active components of host-produced arrestment kairomones are isolated, identified and evaluated in behavioral tests, this host-finding strategy remains only partially understood. This revised version was published online in July 2006 with corrections to the Cover Date.     

Studies on the Utilization of Hydrocarbons by Microorganisms

In the course of study on the utilization of methyl-substituents of mono-cyclic aromatic hydrocarbons by Pseudomonas aeruginosa S668B2, some organic acids and phenolic compounds were found to be produced in culture broth.

Strain S668B2 was capable of producing ultraviolet absorbing and fluorescent substances from m-xylene. These substances were isolated in the form of crystal and identified as 3-methyl salicylic acid and m-toluic acid.

Strain S668B2 also produced ultraviolet absorbing and fluorescent substances from pseudocumene (1,2,4-trimethyl benzene). These substances were isolated in the crystalline form and identified as 3,4-dimethyl benzoic acid and 3,4-dimethyl phenol.

Strain S668B″ did not attack o-xylene. Under the similar conditions Pseudomonas desmolytica S449B3, which produced a large amount of cumic acid from p-cymene, did not oxidize o-xylene, but grew on p-xylene, m-xylene and 1,2,4-trimethyl benzene.

None out of 364 soil samples gave microorganisms which utilize o-xylene as a sole carbon source.     

On the Mechanism of Metabolism of (−)-Epicatechin

(?)-Epicatechin was administered orally to rabbits and vanillic acid, 3-hydroxybenzoic acid, protocatechuic acid, and three kinds of neutral substances were found to be excreted in the urine. The three kinds of neutral substances were identified as 1-δ-(3-methoxy-4-hydroxyphenyl)-, 1-δ-(3-hydroxyphenyl)-, and 1-δ-(3,4-dihydroxyphenyl)-γ-valerolactones, which are optical isomers of the three kinds of neutral substances excreted after administration of (+)-catechin. From the presence of these intermediate metabolites, it was verified that (?)-epicatechin is metabolized by the same mechanism as (+)-catechin described earlier.     

GROWTH-INHIBITORS AND GROWTH-PROMOTERS IN ENTEROMORPHA COMPRESS A (CHLOROPHYTA)1

Methanol extracts from the alga Enteromorpha compressa (L.) Grev. contain substances which inhibit the elongation of Lepidium roots. Chromatographic separation of the inhibiting substances revealed that one of the inhibitory zones of the chromatograms had properties of the so-called inhibitor β. Neither abscisic acid (ABA) nor lunularic acid proved to be responsible for the growth-inhibiting property of this zone. Moreover, the extracts contain substances which promote the elongation of Avena coleoptile segments. One of these substances could be tentatively identified as indole-3-acetic acid by thin-layer and gas-liquid chromatography. (In addition to indole-3-acetic acid a second growth-promoting factor with the properties of the so-called accelerator α could be detected.)     

Attraction of Pinewood Nematode to Endoparasitic Nematophagous Fungus Esteya vermicola

The investigations on attraction of nematodes to nematophagous fungi have mostly dealt with the nematode-trapping species. Esteya vermicola is the endoparasitic fungus of pinewood nematode (PWN) with high infection activity. In the present study, the attraction of PWNs to E. vermicola was investigated. It was confirmed that the living mycelia and exudative substances of E. vermicola were attractive to PWN. Compared with the nematode-trapping fungus A. brochopaga as well as nematode-feeding fungus B. cinerea, E. vermicola showed the significantly strongest attraction ability to nematode. It therefore appeared that the attraction ability reflects the dependence of the fungi on nematodes for nutrients. Furthermore, a new method was developed and used in the study to confirm the effect of volatile substances for the attraction of nematode to fungi. The results suggested that the attractive substances were consisted of avolatile exudative and volatile diffusing compounds.     

Effect of Carbon Source on the Antimicrobial Activity of the Air Flora

Summary In an attempt to screen for air flora producing new potent antimicrobial substances, Bacillus megaterium NB-3, Bacillus cereus NB-4, Bacillus cereus NB-5, Bacillus subtilis NB-6 and Bacillus circulans NB-7, were isolated and were found to be antagonistic to bacteria and/or fungi. Production of antimicrobial substances by the bacterial strains was greatly influenced by variation of carbon sources. Glycerol strongly enhanced the antimicrobial activity of strains NB-3 and NB-6, whereas glucose increased the antimicrobial activity of strains NB-4 and NB-5. The maximum antibiotic yield of NB-7 was achieved with fructose as a carbon source. Starch (Bacillus megaterium NB-3), maltose (Bacillus cereus NB-5), glycerol (Bacillus circulans NB-7), arabinose, ribose (Bacillus cereus NB-4) and arabinose, fructose, glucose, ribose and sucrose (Bacillus subtilis NB-6) repressed the production of antimicrobial substances by the respective bacterial strains.     

Evidence for gibberellin-like substances in phloem exudate of higher plants

Summary Samples of sieve-tube sap were obtained as honeydew from aphids feeding on three species of higher plants. The honeydew was extracted, chromatographed and tested in several bioassays for the presence of gibberellin-like substances. The bioassay results indicated that gibberellin-like substances were translocated in the phloem of dandelion (Taraxacum officinale), broad bean (Vicia faba) and willow (Salix viminalis). Results obtained with willow showed that the concentration of gibberellin-like substances in the sieve-tube sap is daylength dependent, high levels being present in plants maintained under long days and low levels in short day plants.     

Biological activity of hydroxyanthraquinones and their glucosides toward microorganisms

Five mono- and dihydroxyanthraquinones as well as 12 of their glucosides (both free and acetylated) were tested with six different microbial species using the plate-diffusion method. None of the tested substances was active againstEscherichia coli, 15 of the 17 substances displayed an activity towardBacillus subtilis, Bacillus cereus, Candida albicans, Saccharomyces cerevisiae andStreptomyces aurecfaciens. Relationships between the substance type and biological activity are discussed.     

Isolation and identification of potent allelopathic substances in rattail fescue

Aqueous methanol extracts of rattail fescue (Vulpia myuros) inhibited the growth of roots and shoots of cress (Lepidium sativum), lettuce (Lactuca sativa), alfalfa (Medicago sativa), timothy (Phleum pratense), Digitaria sanguinalis and Lolium multiflorum. Increasing the extract concentration increased the inhibition, suggesting that rattail fescue may have growth inhibitory substances and possess allelopathic potential. The aqueous methanol extract of rattail fescue was purified and two main inhibitory substances were isolated and identified by spectral data as (−)-3-hydroxy-β-ionone and (+)-3-oxo-α-ionol. Both substances inhibited root and shoot growth of cress at concentrations greater than 0.3 μM. The concentrations required for 50% growth inhibition on root and shoot growth of cress, lettuce, alfalfa, timothy, D. sanguinalis and L. multiflorum were 2.7–19.7 μM for (−)-3-hydroxy-β-ionone, and 2.1–34.5 μM for (+)-3-oxo-α-ionol. The concentration of (−)-3-hydroxy-β-ionone and (+)-3-oxo-α-ionol, respectively, in rattail fescue was 7.8 and 3.7 μg g⁻¹ fresh weight. Considering the endogenous level and the inhibitory activity, (−)-3-hydroxy-β-ionone and (+)-3-oxo-α-ionol may work as allelopathic substances in rattail fescue through the growth inhibition of neighboring plant species.     

The effects of antifungal substances on some zoosporic fungi (Kingdom Fungi)

Zoosporic fungi constitute a large group of true fungi which inhabit freshwater, brackish, marine and soil ecosystems. In general, very little is known about the effects of antifungal substances on the growth and survival of most species. This review focuses on experimental research with those isolates which have been studied, especially in some species of Synchytrium, Olpidium, Batrachochytrium, Allomyces, Blastocladiella, Neocallimastix. These genera represent genetically diverse groups. Although the research discussed here is restricted to a small sample, some general conclusions can be reached about zoosporic fungi as a whole. Like many other eukaryotic microorganisms, zoosporic fungi are sensitive to a large number of antibiotics, fungicides, surfactants, bacterial metabolites, metabolic poisons, proteins, heavy metals and other antifungal substances. These include substances commonly released into the environment for the control of plant and animal diseases, for increasing production of domestic animals and in the form of waste products from industry. It is possible that the release of antifungal substances into the environment might cause significant changes in the community structure of zoosporic fungi as well as of other groups of microorganisms which play significant roles in food web dynamics and ecosystem complexity. However, this needs documentation by quantitative studies. For these reasons, extensive research on the effects of antifungal substances is much needed.     

A cross-phyla response to Daphnia chemical alarm substances by an aquatic oligochaete

Although chemical alarm substances from damaged heterospecifics have been well documented to induce defense mechanisms in potential prey, data about antipredator responses to alarm cues from prey organisms of a distinct phylum are scarce. In this study, we analyze the response of an oligochaete to chemical alarm substances from distantly related cladocerans. We conducted laboratory experiments to investigate whether the aquatic oligochaete Stylaria lacustris detects and responds to alarm substances from Daphnia. The oligochaetes were exposed to alarm substances from Daphnia magna, which is a member of the same prey guild, and D. hyalina, which is vulnerable to different predators. S. lacustris increased the fission rate in response to cues from conspecifics and the heterospecific D. magna. These species share common predators, especially damselfly larvae and hydras. In contrast, chemical cues released from D. hyalina did not induce an increase in the reproductive rate of the oligochaetes. D. hyalina is a pelagic species and is not included in the diet of predators preying upon S. lacustris. Our results indicate cross-phyla responses among invertebrates (Annelida and Arthropoda), and suggest strong selection pressures to respond to heterospecific alarm substances. The oligochaete S. lacustris is able to differentiate chemical substances released from damaged Daphnia of two different species. These results show that alarm cues released from damaged Daphnia may be species-specific. However, further studies on the chemical structure of alarm substances in cladocerans are needed to support this hypothesis.     

Production of extracellular polymeric substances from Rhodopseudomonas acidophila in the presence of toxic substances

A hydrogen-producing photosynthetic bacteria strain, Rhodopseudomonas acidophila, was used to investigate the production of extracellular polymeric substances (EPS) in the presence of toxic substances and the effect of toxicants on bacterial surface characteristics. Addition of the toxic substances including Cu(II), Cr(VI), Cd(II) and 2,4-dichlorophenol (2,4-DCP) stimulated the production of EPS but reduced the cell dry weight. At concentrations of 30 mg l⁻¹ Cu(II), 40 mg l⁻¹ Cr(VI), 5 mg l⁻¹ Cd(II) and 100 mg l⁻¹ 2,4-DCP, the EPS content increased by 5.5, 2.5, 4.0 and 1.4 times, respectively, than the control. These toxic substances also greatly influenced the proteins/carbohydrates ratio of EPS. The ratios in the presence of toxic substances were always higher than that of control. Furthermore, under toxic conditions, the increase in the protein content far exceeded than that of others in EPS, suggesting that extracellular proteins could protect cells against toxic substances. The toxic substances significantly changed the surface characteristics and flocculation ability of R. acidophila, such as surface energy, relative hydrophobicity and free energy of adhesion.     

Functional properties of anti-inflammatory substances from quercetin-treated Bifidobacterium adolescentis

Abstract

The genus Bifidobacterium is well known to have beneficial health effects. We discovered that quercetin and related polyphenols enhanced the secretion of anti-inflammatory substances by Bifidobacterium adolescentis. This study investigated characteristics of the anti-inflammatory substances secreted by B. adolescentis. The culture supernatant of B. adolescentis with quercetin reduced the levels of inflammatory mediators in activated macrophages. Spontaneous quercetin degradant failed to increase anti-inflammatory activity, while the enhancement of anti-inflammatory activity by quercetin was sustained after washout of quercetin. Physicochemical treatment of the culture supernatant indicated that its bioactive substances may be heat-stable, non-phenolic, and acidic biomolecules with molecular weights less than 3 kDa. Acetate and lactate have little or no effect on nitric oxide production. Taken together, the anti-inflammatory substances secreted by B. adolescentis may be small molecules but not short chain fatty acids. In agreement with these findings, stearic acid was tentatively identified as a bioactive candidate compound.     

Osteoclast-Forming Suppressive Compounds from Makomotake,Zizania latifolia Infected with Ustilago esculenta

A novel compound (1) and a known one (2) were isolated from Makomotake, Zizania latifolia infected with Ustilago esculenta, as osteoclast-forming suppressive substances.     

Production of Alkaline Protease from n-Paraffins by a Kabicidin Resistant Mutant Strain of Fusarium sp.

An antagonistic fungus to Valsa ceratosperma was isolated from soil, and identified as Fusarium solani. The fungus was found to produce at least two antifungal substances in stationary culture. These two substances were isolated from their culture filtrate as chromatographically homogeneous, amorphous solids. Their examined physico-chemical properties appeared to be identical with cyclosporin A and C, obtained from the fermentation broth of Trichoderma polysporum, and they showed a pronounced inhibitory effect on growth of V. ceratosperma.     

A physico-chemical theory of sweet and bitter taste excitation based on the properties of the plasma membrane

Summary This paper is concerned with physical and chemical changes occurring in the taste buds due to the presence of sapid substances, and not with the nervous mechanism transmitting impulses to the brain. From this standpoint taste phenomena are closely allied with general cell physiology or pharmacology. It has been shown that the great majority of anesthetic or toxic substances have a bitter taste and it is considered that the same structural changes occur in the cell membranes in taste buds as in other cells of the body when such substances are present. From consideration of a large amount of experimental data on the taste of organic compounds it is shown that thesweet and bitter substances are chemically very closely related and there is no line of demarcation between them. In many homologous series there is a continuous (rather than discontinuous) transition from sweet to bitter. Sweet substances having a bitter after-taste are also common.It has been pointed out that it is a general property of anesthetics to be stimulants (i. e. to accelerate cell activities)when in low concentrations. The continuous transition from stimulant to narcotic action is correlated with the sweet-bitter transition. FollowingClowes, Lillie and others the cell membrane is looked upon as a balanced emulsion partly of the water in oil type and partly of the reverse type.The phenomena cited above have been explained in terms of adsorption and surface tension action of substances on this emulsion system and the consequent changes in cell membrane permeability due to changes in the phase ratio of the emulsion types.     

Growth promoting and inhibiting effects of extracellular substances of soil microalgae and cyanobacteria on Escherichia coll and Micrococcus luteus

Different taxa of chlorophycean, trebouxiophycean and xanthophycean soil microalgae and of cyanobacteria have been tested for the release of substances that inhibit the growth of either Echerichia coli (Migula) Castellani et Chalmersor Micrococcus luteus (Schroeter) Cohn. Experiments suggest two types of antibacterial effects: one type is constitutive; that is, the antibacterial activity is always present in the algal culture medium, as is the case with the Chroococcus turgidus (medium that inhibits the growth of Escherichia coli). The other type is induced; that is, the antibacterial activity occurs only when algae are in contact with bacteria. This is the case when growth of Micrococcus luteus is inhibited in co‐culture with Chroococcus turgidus (Kützing) Nägeli or with Xanthonema debile (Vischer) Silva and when growth of Escherichia coll is inhibited in co‐culture with Tetracystis sp. As well as inhibition, promotion of bacterial growth was observed. This was probably an unspecific effect resulting from soluble organic and inorganic substances, such as carbohydrates, that are generally present in algal cultures.