Movement of Ions and Electrogenesis in Microorganisms

The relationship between movement of ions and the electricalproperties of microorganisms (algae, fungi, and bacteria) arereviewed, with particular emphasis on the giant alga, Nitella,and the fungus, Neurospora. The hypothesis is presented thatthere are two basically different components to the membranepotential of both organisms: (1) one arising from the diffusionof sodium, potassium, and hydrogen ions down their chemicalgradients, and (2) one associated with the utilization of energyand the active efflux of hydrogen ions, and attributed to an"electrogenic H⁺ pump." Numerous discrepancies between the measuredelectrical properties of the algae or fungi and the predictionsof ordinary ion-diffusion theory can be accounted for by suchan H⁺ pump, and its existence is further supported by a fewindirect experiments on the bacteria.     

A Reinvestigation of Bacterial Symbiosis in Coprosma, Myoporum, Metrosideros, Leptospermum, and Vitex

A reinvestigation by optical and electron microscopy of sevenplant species, native to New Zealand, howed no bacteria in anyof the plant cells or secretions claimed to contain them. Itis concluded that if these symbioses sometimes occur, they donot constitute a general feature. No previous work has described the presence of micro-organismsin the bud secretions of Vitex lucens, but a large populationof bacteria and fungi were observed here, during the courseof this study.     

Immunological Studies on Glutamine Synthetase using Antisera Raised to the Two Plant Forms of the Enzyme from PhaseolusRoot Nodules

Antisera specific for glutamine synthetase (GS) have been raisedto the two forms of the enzyme from the plant fraction of rootnodules of Phaseolus vulgaris. The two antisera recognized bothforms of plant nodule GS and also the enzyme from some otherhigher plant tissues. However, the antiserum did not cross-reactwith GS from free-living or bacteroid Rhizobium Phaseolinorwith the enzyme from representatives of green algae, fungi,mammals and bacteria. Results are presented which suggest thatone of the forms of nodule GS is closely related to the rootenzyme whereas the other, the 'nodule specific' form, has someantigenic differences Key words: Phaseolus Vulgaris, Legume/Rhizobium symbosis, Glutamine synthetase, Immunology     

Effect of Plant Growth Promoting Bacillus Strains on Pine and Spruce Seedling Growth and Mycorrhizal Infection

Rifamycin-resistant derivatives of plant growth promotingBacilluspolymyxa strains L6, Pw-2, and S20 were used to evaluate theinteraction of bacterial–mycorrhizal co-inoculation onpine and spruce seedling growth. We were particularly interestedin determining if the mechanism by which bacteria stimulatedseedling growth depended on the presence of ectomycorrhizae.Mycorrhizal inoculum was introduced by adding 2ml of one ofsix forest floor soil types originating from different spruceand pine stands to seedling containers. Mycorrhizal roots developedin 34% of pine and 27% of spruce seedlings treated with forestsoil, but no differences between forest soils were detected.Most mycorrhizae were formed byWilcoxinasp. (E-strain) (98%for spruce and 67% for pine); small numbers ofAmphinema-like,Myceliumradicis atrovirens, Suillus-like,Thelephora-like, andTuber-likemycorrhizae were also found on pine (27% in total).Thelephora-likefungi comprised 2% of spruce mycorrhize. In the absence of bacterialinoculum, spruce seedling biomass was positively correlatedwith the number of mycorrhizal root tips, but this trend wasnot detected in spruce inoculated with bacteria or in pine.Bacterial inoculation did not influence the mycorrhizal statusof seedlings, but all threeBacillusstrains stimulated growthof both conifer species. Root biomass, in particular, was significantlyenhanced by up to 18% compared with uninoculated controls. Mycorrhizalfungi improved the growth of spruce seedlings, but plant growthpromotion byBacilluswas similar for mycorrizal and non-mycorrhizalseedlings of both species. Our results suggest thatBacillusstrainsL6-16R, Pw-2R, and S20-R enhance conifer seedling growth througha mechanism unrelated to mycorrhizal fungi. Hybrid spruce; Picea glaucaxengelmannii ; lodgepole pine; Pinus contortavar.latifoliaEngelm.; inoculation; Bacillus polymyxa; seedling growth promotion; mycorrhizae     

Types of Rot, Rate of Rotting, and Analysis of Pectic Substances in Apples Rotted by Fungi

The rate at which the fungi grew through apples was determinedin various ways and used to estimate their rate of linear advance.Five fungi were studied;they were Sclerotinia fructigena (firm-browncoloured rot, rapid growth through apples), Botrytis cinerea(soft, light-brown coloured rot, rapid growth through apples),Psyrenochaeta furfuracea (firm to soft rot, variable in colourbut generaly dark, slow growth through apples), Penicilliumexpansion A (soft, white rot, slow growth through apples) andPenicillium expansum B (soft, white rot, medium rate of growththrough apples). S. fructigena which had the highest rate oflinear advance which was about three times that of P. furfuraceawhich had the lowest. Methods for extracting different types of pectic substancesfrom sound and rotted tissues are described, and details aregiven of a rapid and reasonably accurate colorimetric methodof determining the anhydrogalacturonic acid content of theseextracts. The firm-rot fungi reduced the water-insoluble pecticsubstances by 10–20 per cent., but the soft-rot fungicaused much larger changes, up to 70 per cent. being degraded,The firm-rot and soft-rot fungi had different effects on thepectic substances insoluble in dilute acid but soluble in dilutealkali. The soft-rot fungi had little effect on these substances,or reduced their concentration, whereas the firm-rot fungi causedsubstantial increases compared with sound tissue. These resultsare considered in terms of pectic enzyme activity. Analysisof extracts by paper chromatography showed that galacturonicacid, absent from sound tissue, was present in each type ofrotted tissue. Di- and tri-galacturonic acids were present inrots caused by P. expansum, and these rots probably also containedproducts from the break-down of other polysaccharides.     

Histomorphological changes in the reproductive condition of parasitized marine planktonic copepods

Changes in the internal morphology of parasitized copepods sampledin the Gulf of Naples from 1986 to 1988 were investigated usingboth light and transmission electron microscopy. The most commonand devastating form of infection was due to the parasitic dinoflagellateSyndinium, which induced gross modifications in the internaland external morphology of the host population. The parasitereduced fecundity and longevity of infected individuals, whichmainly included juvenile and female populations of the copepodParacalanus parvus. Infection rates for this species were ashigh as 12% for. juveniles and 13% for adult females for theperiod investigated. Infection by the parasitic dinoflagellateBlastodinium induced less negative effects on the reproductivebiology of their hosts. This pathogen did not lead to sexualcastration and oogonal development appeared normal. Other formsof infestation were rare and included infections due to protozoa,fungi and bacteria. ^*Died tragically at sea during a cruise on December 15, 1988     

The Role of Marine Fungi in the Penetration of Calcareous Substances

All publications dealing with fungi described from marine calcareoussubstrates are discussed in this survey of the literature. Originalinvestigations of fungi from lime tubesof teredinids are included.Wood-inhabiting marine fungi, especially in warm waters, growwithin calcareous linings of teredinid burrows. Fruiting structuresof the Ascomycetes, Halosphaeria quadricornuta and Remisporasalina, and the Deuteromycete, Periconia prolifica, form cavitiesin the tube linings, making them brittle and soft. Representativesof Cirrenalia and Humicola sporulate on the surface of calcareouslinings. The fungus, Pharcidia balani, sometimes referred toas a lichen, decomposesshells of barnacles and molluscs. AnotherAscomycete, Lulworlhia kniepii, parasitizes calcareous algae,probably living on the middle lamellae, not on the calcifiedcell walls.     

The Galls on Forsythia intermedia Zab.

The galls on Forsythia intermedia Zab. consist of much-branched,root-like structures embedded in corky material which appearsto be sloughed-off from them. These gall ‘roots’have 7 to 14 vascular bundles compared with the 5 of normalroots and contain much more IAA. When galls were incubated in damp chambers the gall ‘roots’extended their growth. These extensions had a root-cap and root-hairsbut also had more vascular bundles than normal and they didnot respond geotropically like normal roots. Two fungi, Gibberella baccata (Wallr.) Sacc. (conid, stat. Fusarlumlateritium Nees.) and Phomopsis dominici Trav. were associatedwith die-back of gall ‘roots’ and two bacteria resemblingCorynebacterium fascians (Til.) Dowson and Agrobacterium tumefaciens(Sm. and Towns.) Conn respectively were isolated from galls.All produced IAA in culture media but their role in the etiologyof the gall, if any, remains in doubt.     

纵坑切梢小蠹对云南松蛀害研究

在昆明地区,纵坑切梢小蠹Tomicus piniperda L.表现出枝梢聚集、树干蛀害等重要的行为学特征,形成三种基本蛀害模式。横坑切梢小蠹、蓝色伴生真菌参与了纵坑切梢小蠹危害过程,并在其中发挥积极作用。上述因素的综合影响,加强了纵坑切梢小蠹对云南松Pinus yunnanensis寄主树木的危害能力。     

Fungal Assciations: I. Synergistic Relation between Rhizoctonia solani Kuhn and Fusarium solani Snyder and Hansen in causing a Potato Tuber Rot

Rhizoctonia solani, Fusarium solani, and Phoma foveata werechosen for the study of disease caused by these fungi in differentcombinations in potato tubers. An initial Rhizoctonia infection,when followed by a Fusarium infection, gave an extensive rottingwith external pimple-like formations in some cases. This typeof rotting could not be brought about by individual infectionswith either of the two fungi, or jointly by them when Fusariumwas inoculated first. Microscopic observations of infected matureand young potato tubers showed that Rhizoctonia grew intracellularlywhen infected alone, whereas it grew inter- as well as intra-cellularlyin the successive double infection. Fusarium formed more haustorium-likestructures when inoculated alone that when it followed Rhizoctonia.The length of these structures in the double infection was greaterin mature than in young tubers. Atmospheric humidity affectedthe amount of rotting, the shape and colour of the rot, andthe morphology of the fungus in the tissue.     

Accelerating Strawberry Seed Germination by Fungal Infection

Germination of strawberry seed was accelerated by natural andartificial infections of Ulocladium charatarum and other fungi,including the Arthrinium state of Apiospora montagnei and aCladosporium sp. Germination was variously promoted by fungiboth in light and darkness, on damp filter paper, water andmalt agar plates and on horticultural compost. Germinated seedlingswere apparently undamaged by these infections, although whencultured on malt agar the seedlings were overgrown by the fungus.Several other fungi promoted germination, but three of themlater killed the seedlings. Germination of seed of all threecultivars that were tested was promoted by fungal infectionwhich probably promoted germination by hastening breakdown ofthe seed coat. Strawberry, Fragaria ananassa Duch., germination, fungus     

Abnormal Stomatal Opening in Coconut Palms Affected with Root (Wilt) Disease

Studies on the stomatal regulation in the root (wilt) affectedcoconut palms (Cocos nucifera L.) revealed that the diseasedpalms had low stomatal resistance compared to the healthy palms,irrespective of their age. The same trend was observed whetherthe determinations were made at different times of the day (6–18h) or under irrigated and unirrigated conditions or in differentseasons (‘dry’ and ‘wet’). Thus, thestomatal regulation was significantly impaired in the diseasedpalms resulting in excessive water loss compared to the healthypalms. Results are discussed with the available literature onother similar disease caused by fungi, bacteria and mycoplasma-likeorganisms in different plants. Key words: Cocos nucifera L., Stomatal resistance, Root (wilt) disease     

Development of a Model to Predict the Effect of Temperature and Moisture on Fungal Spore Longevity

A model was developed to quantify the effect of temperatureand moisture content on the longevity of conidia of the entomopathogenicfungusMetarhizium flavoviride . This model incorporated a negativesemi-logarithmic relation between longevity and temperatureand a negative logarithmic relation between longevity and moisturecontent. Replacing the latter with a negative semi-logarithmicrelation between longevity and the equilibrium relative humidityof the conidia was also effective. The latter model was appliedsuccessfully to observations on the survival of conidia of afurther four entomopathogenic fungi (Metarhizium anisopliae,Beauveria bassiana ,Beauveria brongniartii, andPaecilomycesfarinosus ) and ascospores, conidia or uredospores of four phytopathogenicfungi (Alternaria porri ,Helminthosporium oryzae ,Uromyces appendiculatus, andSclerotinia sclerotiorum ) across a wide range of differenttemperatures and relative humidities. The sensitivity of sporelongevity to both temperature and equilibrium relative humidity,and the upper and lower relative humidity limits to the applicationof the model, varied considerably between entomopathogenic andphytopathogenic fungi, among species within each group, andamong different strains within certain species. Metarhizium flavoviride W. Gams & J. Roszypal; entomopathogenic fungi; phytopathogenic fungi; spore survival; storage environment; conidia; uredospore; ascospore     

Observations on the Biology of Fomes annosus, with Particular Reference to East Anglian Pine Plantations: II. Spore Production, Stump Infection, and Saprophytic Activity in Stumps

F. annosus produces conidia abundantly in culture but rarelyunder natural conditions. Sporophorea are formed on stumps anddying trees throughout the year provided that the humidity issufficiently high. Spore discharge in the plantations may occurat any time of year, but slowa down or ceases during very dryweather. It takes place at low temperatures, ceasing only whensporophores freeze. In the laboratory, F. annosus basidiospores germinate in relativehumidity exceeding 92 per cent. on freshly cut, unsterilizedpine wood. Viability is lost rapidly in light at temperaturesabove 15°C. Under humid conditions F. annosus spores will infect freshlycut pine stumps. There is evidence that spores of F. annosus washed down intosoil remain viable for at least a short period and that stumpscovered with soil are infected from this source. F. annosusspores can infect stumps for only a few weeks after felling,colonization after a longer interval probably beingprevdntedby competing fungi. In stumps inoculated with a mixed suspensionof F. annosus and Peniophora gigantea spores, Fomes at firstcolonized the wood but was soon replaced by P. gigantea. Otheraspects of competition are discussed. The incidence of natural infection in stumps and the factorsaffecting it are discussed Growth rates of F. annosus on malt agar and in lengths of pineroot are given. The fungus grows in stump roots at about 1 m.per year, and so closely approaches adjacent trees within ayear of thinning the plantation: In large stumps, F. annosusmay survive 15 or even 30 years after felling. Data are givenwhich suggest that the infective capacity of stumps containingF. annosus is greater in alkaline than in acid mils, while replacementby other fungi is slower. Competition of F. annosus with other fungi during colonizationof stumps is discussed. The parasite can grow along roots alreadyoccupied by certain fungi but not along roots containing others.The probable course of succession in stumps rotted by F. annousis described.     

Production of a Fungistat and the Role of Fungi during Germination of Digitalis purpurea L.cv. Gloxiniaflora Seeds

The seed coats of Digitalis purpurea L. cv. Gloxiniaflora werecultured for indigenous fungi. Alternaria alternata (Fries)was identified as the sole fungus on seeds freshly harvestedfrom unopened capsules, whereas A. alternata, Rhizopus arrhizus(Fischer), Penicillium sp. and other fungi appeared on storedseeds. The appearance of fungi in seed cultures was seasonal,being more frequent in winter and early spring than in summerand autumn. Alternaria grew well on autoclaved seeds, on dehiscentseed coats, or on seed coats separated from the embryos of ungerminatedseeds. Rhizopus did not grow on these but grew weakly on theculture medium from viable seeds. A. alternata appears to functionas a degradation agent for the seed coat subsequent to germination.Neither fungus was found to be essential to germination of Digitalisseeds. Bioassay of the culture medium from germinating seedsshowed that a fungistat effective against both Alternaria andRhizopus is produced coincident with germination. Based on chromatographicanalysis, the fungistat appears to be a cardenolide. Alternaria alternata (Fries), cardenolides, Digitalis purpurea L. cv, Gloxiniaflora, fungistats, germination, Rhizopus arrhizus (Fischer)     

Fungal Assciations: II. Cultural Studies on Rhizoctonia solani Kuhn, Fusariutn solani Snyder and Hansen, and Other Fungi, and Their Interactions

Several types of interaction between Rhizoctonia solani, Fusariumsolani, and Phoma foveata were found when these fungi were grownon potato-dextrose agar. After being used by Rhizoctonia a potatomash medium gave better growth of Rizoctonia and Fusarium thanit did when the medium was initially used by Fusarium; and thiswas so whether the reaction of the spent medium was readjustedor not. It is suggested that potato mash medium used by Fusariumcontains a thermostable factor(s) affecting the subsequent growthof Rhizoctonia or Fusarium. The range of pH values suitable for Rhizoctonia growth was narrowerthan that for Fusarium, optimum values being approximately 5•9for the former and 7•8 for the latter. In mixed culturesof the two fungi on potato-dextrose agar adjusted to differentpH values, the fungus for which the reaction of the medium wasmore suitable usually became visually predominant after sometime. A study of various carbon sources showed that poor growth ofRhizoctonia was obtained when pectin was used as the sole sourceof carbon. On a pectin-agar medium, the rate of growth of aRhizoctonia colony increased on the sector which lay towardsan adjacent Fusarium colony; also, after the two fungi camein contact, there was more rapid growth of Rhizoctonia roundthe Fusarium colony than elsewhere. On a synthetic liquid mediumwith pectin as the carbon source better Rhizoctonia growth wasobtained when Fusarium-spent medium was added to it than whenRMzoctoma-spent medium was added. Rhizoctonia showed partial deficiencies in thiamine, biotin,and inositol. Both the extract of Fusarium mycelium, grown onvitamin-free medium, and the Fusarium-spent medium, stimulatedthe growth of Rhizoctonia on vitamin-free medium.     

In situ determinations of bacterial selectivity and filtration rates by five cladoceran zooplankters in a hypertrophic subtropical reservoir

Cladoceran in situ feeding rates on natural bacteria labelledwith [methyl-³H] were studied in parallel with feeding ratedeterminations on ¹⁴C-labelled Chlorella in a hypertrophic subtropicalreservoir (Lake Hartbeespoort) through spring and summer (1986/87).Community filtration rates (CFR5) on bacteria and algae weresimilar, but selection for Chlorella (relative to natural bacteria)increased from midsummer in association with declining bacterialdensity and increasing dominance of ‘inedible’ componentsof the natural phytoplankton. Species-specific filtration rates(SSFRs) were determined for Daphnia pulexllongispina, Ceriodaphniareticulata, Diaphanosoma excisum, Bosmina longirostris and Moinamicrura during their respective seasonal occurrence in the studyperiod. SSFRs on algae and bacteria increased with body length(L, mm) in all species apart from Bosmina. Species-specificdifferences in absolute feeding rate (FR, ml animal^–1day^–1), the slope of the FR-L relationship and bacteriaselectivity were evident. The feeding rate of all cladoceranson bacteria is described by the power equation FR 5.231L^1.42FR values on bacteria relative to FR values on algae averaged     

The Role of Superoxide Dismutase in Regulating the Light Emission of Luminescent Fungi

Luminescent fungi spontaneously emit light during certain stagesof their life cycles. Most of them are luminous during a partof their mycelial stage, but not many of them are luminous whenthey form fruiting bodies. In the case of Panellus stipticus,both the mycelium and the fruiting body can be luminous, andthe emission of light takes place when its luciferin is aerobicallyoxidized in the presence of the superoxide anion (O₂) and acationic surfactant. It is highly likely that the luminescencereactions of all kinds of luminous fungi are basically the sameas that of P. stipticus. In order to determine the factor thatmakes a fungus luminous or non-luminous, we studied the relationsbetween the light emission of fungi at various growth stagesand the contents of luciferin, its precursor, superoxide dismutase(SOD), and catalase, on six species of luminescent fungi: Armillariellamellea, Mycena citricolor, Mycena lux-coeli, Omphlotus olearious,Panellus stipticus, and Pleurotus japonicus. The analysis ofthe data suggested that the fungi generally contain the componentsnecessary for light emission, but also contain very large amountsof SOD which destroy O₂^–. If an appreciable amount ofSOD is distributed at the site of light emission, the luminescencereaction is prevented. For the reaction to take place, it isessential that the SOD activity at the site is sufficientlylow or inhibited, despite the high content of SOD in the wholetissue. Thus, the level of SOD activity at the site of lightemission appears to be a limiting factor in regulating the luminescenceof fungi. Key words: Bioluminescence, chemiluminescence, luminous fungi, superoxide ion, superoxide dismutase     

The Nature of the Resistance of Oats to the Take-all Fungus: II. INHIBITION OF GROWTH AND RESPIRATION OF OPHIOBOLUS GRAMINIS SACC. AND OTHER FUNGI BY A CONSTITUENT OF OAT SAP

Growth of Ophiobohu gramimt and of O. gramims var. avenae isinhibited by concentrations of 3·3-4·0µg./ml.,and respiration by concentrations of 55µg./nil. of a partiallypurified substance from oat-leaf sap. The two varieties appearto be equally sensitive. The filtrate of boiled sap is inhibitorybut here dilution of the sap permits better growth of isolatesof var. avenae. Sap from oat roots is inhibitory to O.graminisonly, and fractionation of the sap shows that the inhibitorcan be masked by a growth stimulant. Inhibition of growth andrespiration can be reduced by glutathione and ascorbic acid,particularly if the inhibitor and reducing agent are previouslyincubated together for a few hours, suggesting that the inhibitoris inactivated on reduction. The capacity of var. avenae toovercome inhibition in the favourable medium provided by thecrude sap more readily than can the type variety is suggestedas the cause of the slight differential activity of the filtrateof leaf sap and the full differential activity of the root sap.Susceptibility of oats to var. avenae would thus be due to conditionsenabling the fungus to overcome toxicity rather than to an absenceof toxicity. Activity of the inhibitor against growth and respiration ofa number of fungi and a few other organisms has been tested.Bacteria and oat and barley roots are not affected but abouthalf of the fungi tested are inhibited although none is as sensitiveas O. gramims. No members of the fungi imperfecti tested aresensitive.     

Further Observations on Fungi Inhabiting Pine Stumps

Growth-rates, both on malt agar and in stump wood, of earlystump colonizers such as Fomes annosus, Pemophora gigantea,Stereum sanguinolentum, and Leptographium lundbergii are higherthan those of later-colonizing agarics. The initial invasionof stump roots usually proceeds via the stump body by fungiwhich infect the cut surface. Although stumps may dry out appreciably shortly after felling,in later stages of decay the moisture content of the wood oftenincreases considerably. Stump decomposition is associated witha succession of decay fungi, the ‘Peniophora’, ‘Hypholoma’,and ‘Tricholoma’ stages being distinguished. Severalphycomycetes and fungi imperfecti colonize decayed, but notfresh, stump wood. P. gigantea is shown to be a vigorous competitor of F. annosusfor initial colonization of stumps: it may also replace F.annosus in stumps. Gliocladium viride and Trichoderma viridecompete with wood-rotting basidiomycetes and sometimes replacethem in very decayed wood.