Spore Release Research Articles

Infection of Myxobolus turpisrotundus sp. n. in allogynogenetic gibel carp, Carassius auratus gibelio (Bloch), with revision of Myxobolus rotundus (s. l.) Nemeczek reported from C. auratus auratus (L.)

Infection of a Myxobolus species, previously identified as Myxobolus rotundus, was detected in 182 of 7892 (2.31%) allogynogenetic gibel carp, Carassius auratus gibelio, in a closed pond culture system in China. Morphological and molecular data showed that this myxosporean is a different species from M. rotundus parasitizing Abramis brama in Europe and is thus designated as a new species, Myxobolus turpisrotundus. M. rotundus (s.l.) ex C. auratusauratus is a synonym of M. turpisrotundus. Plasmodia of M. turpisrotundus develop in the subepidermal tissues of the body surface resulting in an unaesthetic appearance and causing severe economic losses. Prevalence of infection with the myxosporean plasmodia varied seasonally, increasing in winter and decreasing in spring. Prevalence was positively correlated to host size, but no host sex-specificity was found. No infection was observed in other fish species (grass carp, bighead carp and yellow catfish) reared in the same pond, suggesting that the parasite has a relatively strict host specificity. Plasmodia grew gradually as the parasite developed, and reached up to a maximum 5.6 mm in diameter. Plasmodia ruptured naturally to release the mature spores and host fish completely recovered with no mortality. Release of spores and regeneration of lesions were not correlated with water temperature. Histology showed that plasmodia developed sub-epidermally, and that the wall of the plasmodia was composed of a multiple complex structure, including layers of fibroblasts, a collagenous membrane, melanophores and a layer of cup-like cells of unknown derivation and function. The cup-like cells are in direct contact with pre-sporogonic stages located in the peripheral parts of the large plasmodia. No severe host inflammatory response was seen.

Botryosphaeriaceae Species Spore-Trapping Studies in California Vineyards.

The seasonal abundance of Botryosphaeriaceae spp. spores was studied in California vineyards by using glass microscope slides covered with petroleum jelly placed on grapevine cordons and Burkard volumetric spore traps at seven and two different locations, respectively. Correlation analysis was used to determine which meteorological variables (precipitation, relative humidity, temperature, and wind speed) influenced Botryosphaeriaceae spp. spore release. Among all variables, regression analysis resulted in a strong relationship between spore release and precipitation. Additionally, a positive relationship between irrigation and spore release was also observed in the Riverside County vineyard. During the study period, spore discharge of Botryosphaeriaceae spp. occurred from the first fall rain through the last spring rains, coinciding with September to April. However, based on the results obtained from the spore traps, most spores (over 60%) were trapped following rain events during the winter months of December, January, and February, which coincides with the grapevine pruning season. Botryosphaeriaceae spp. spore release was much lower in fall and early spring (22%) and very few or no spores were trapped in late spring and summer (3%). This work suggests that a delay of pruning time in California may be warranted to reduce grapevine infection because the current timing coincides with the greatest period of spore discharge.

Measurements and comparison of primary biological aerosol above and below a tropical forest canopy using a dual channel fluorescence spectrometer

Abstract. Aerosol particle size distributions were measured below and above a tropical rainforest canopy in Borneo, Malaysia, in June/July 2008 using the WIBS-3: a single particle dual channel fluorescence spectrometer. Material in the size range 0.8–20 μm was characterized according to optical equivalent diameter (DP), morphology and fluorescence at 310–400 nm and 400–600 nm following excitation at 280 nm and 370 nm respectively. Particles fluorescent after both excitations are likely to be fluorescent primary biological aerosol particles (FBAP). Measured FBAP number concentration (NFBAP) at both sites exhibited clear diurnal cycles. The largest variability was observed in the understorey, where NFBAP reached a minimum of 50–100 L−1 in late morning. In mid afternoon it exhibited strong transient fluctuations as large as 4000 L−1 that were followed by sustained concentrations of 1000–2500 L−1 that reduced steadily between midnight and sunrise. Above the canopy FBAP number ranged from 50–100 L−1 during the daytime to 200–400 L−1 at night but did not exhibit the transient enhancements seen in the understorey. The strong FBAP fluctuations were attributed to the release of fungal spores below the canopy and appeared to be linked to elevated relative humidity. The mean FBAP number fraction in the size range 0.8 μm

A phylogenetic circumscription of Polytrichastrum (Polytrichaceae): Reassessment of sporophyte morphology supports molecular phylogeny

Mosses arguably possess the most structurally complex sporangia of any extant land plants, a consequence of being the monosporangiophyte lineage most strongly adapted to terrestrial environments. Morphological and functional variation in the mechanisms that regulate spore release in one of the major classes of mosses, the Polytrichopsida, is largely unexplored, while recent research indicates that the most distinctive structure, the peristome, has evolved independently in the Polytrichopsida and in other mosses. The genus Polytrichastrum was separated from Polytrichum on the basis of such sporangial characters, although the critical features had until recently only been examined using light microscopy, and strong evidence from molecular data indicated that Polytrichastrum as currently circumscribed is polyphyletic. Here we use Bayesian ancestral character state reconstruction in conjunction with extensive scanning electron micrographic studies to elucidate probable morphology at ancestral nodes and define natural taxa. As well as clarifying the structure, evolution, and aspects of development of the peristome-epiphragm complex in this highly prominent group of mosses, the results provide a basis for a revised phylogenetic taxonomy in which the species of Polytrichastrum sect. Aporotheca are recognized once more within Polytrichum.

Evaluation of Resistance to Rhabdocline Needlecast in Douglas Fir Variety Shuswap, with Quantitative Polymerase Chain Reaction

A quantitative polymerase chain reaction assay was developed that could detect DNA of Rhabdocline pseudotsugae and R. oblonga among DNA of Douglas fir needles to a limit as low as three copies of target DNA. Differential infection rates of two varieties (seed sources) of Douglas fir interplanted in a field were studied in relation to staggered bud breaks. Infection of Douglas fir var. San Isabel corresponded to ascospore release times for Rhabdocline spp., whereas infection of var. Shuswap Lake did not occur throughout the spore release period during 2 years of study, despite abundant inoculum and adequate moisture during bud break. Rhabdocline spp. DNA was never detected in Shuswap Lake and disease symptoms were not observed in any year. We provide evidence that Shuswap Lake is resistant and probably immune to Rhabdocline spp. infection and Rhabdocline needlecast under Michigan conditions.

Hydrodynamics of raindrop impact stimulate ascospore discharge of Venturia inaequalis

Ascospores of Venturia inaequalis are released from leaves following the impact of raindrops during rain events. Atmospheric humidity or moisture from dew does not have an inductive effect on ascospore release. The hydrodynamics of raindrop impact on leaf surfaces was investigated. Raindrops induced dampened periodic vibrations on leaf surfaces. Vibrations, linear, and/or oscillatory flows of water applied to the leaves all induced spore releases at low energy thresholds. The fungal perceptibility of kinetic energy enables selective discharge of spores when environmental conditions are most conducive to survival. Identification of kinetic effects of rain which reveal start, thresholds, and proportional distribution is not only important for disease prognosis research, but may also serve as a model for a common fungal sensing mechanism.

Size matters for violent discharge height and settling speed of Sphagnum spores: important attributes for dispersal potential.

Initial release height and settling speed of diaspores are biologically controlled components which are key to modelling wind dispersal. Most Sphagnum (peat moss) species have explosive spore liberation. In this study, how capsule and spore sizes affect the height to which spores are propelled were measured, and how spore size and spore number of discharged particles relate to settling speed in the aspherical Sphagnum spores. Spore discharge and spore cloud development were filmed in a closed chamber (nine species). Measurements were taken from snapshots at three stages of cloud development. Settling speed of spores (14 species) and clusters were timed in a glass tube. The maximum discharge speed measured was 3.6 m s(-1). Spores reached a maximum height of 20 cm (average: 15 cm) above the capsule. The cloud dimensions at all stages were related positively to capsule size (R(2) = 0.58-0.65). Thus species with large shoots (because they have large capsules) have a dispersal advantage. Half of the spores were released as singles and the rest as clusters (usually two to four spores). Single spores settled at 0.84-1.86 cm s(-1), about 52 % slower than expected for spherical spores with the same diameters. Settling speed displayed a positive curvilinear relationship with spore size, close to predictions by Stokes' law for spherical spores with 68 % of the actual diameters. Light-coloured spores settled slower than dark spores. Settling speed of spore clusters agrees with earlier studies. Effective spore discharge and small, slowly settling spores appear particularly important for species in forested habitats. The spore discharge heights in Sphagnum are among the greatest for small, wind-dispersed propagules. The discharge heights and the slow settling of spores affect dispersal distances positively and may help to explain the wide distribution of most boreal Sphagnum species.

Reproductive phenology of the introduced kelp Undaria pinnatifida (Phaeophyceae, Laminariales) in Port Phillip Bay (Victoria, Australia)

A thorough understanding of the reproductive phenology of introduced species is crucial for effective management and control. Undaria pinnatifida is an invasive macroalga from the Northwest Pacific which has been recently introduced into three countries in the Southern Hemisphere: Australia, New Zealand and Argentina. Reproductive phenological studies in Port Phillip Bay, Australia, were undertaken and compared with other populations in the Southern Hemisphere, especially with those from Tasmania which were suspected to be very different. The growth season began earlier in Port Phillip Bay than in Tasmanian populations, and abundance was higher. Growth rates were lower in Port Phillip Bay, but this might be due to the different morphology of both populations. The maximum spore release competency of U. pinnatifida in Port Phillip Bay was 12.1 × 105 spores cm−2 h−1 which is 20 times the maximum obtained in Tasmania (0.6 × 105 spores cm−2 h−1). For most of the growth season, spore release competency ranged between 2 and 3 × 105 spores cm−2 h−1, 3–5 times more than in Tasmania. Undaria pinnatifida has not been established outside Port Phillip Bay in continental Australia, but a precautionary approach should be undertaken in order to avoid further spread. Monitoring for early detection and removal of immature sporophytes prior to spore release seem to be the best options. This monitoring should be continuous since new recruits may appear throughout the growth season (April–February) and it should be combined with informative programmes to reduce the chances of spread.

A Strategy for the Proliferation of Ulva prolifera, Main Causative Species of Green Tides, with Formation of Sporangia by Fragmentation

Ulva prolifera, a common green seaweed, is one of the causative species of green tides that occurred frequently along the shores of Qingdao in 2008 and had detrimental effects on the preparations for the 2008 Beijing Olympic Games sailing competition, since more than 30 percent of the area of the games was invaded. In view of the rapid accumulation of the vast biomass of floating U. prolifera in green tides, we investigated the formation of sporangia in disks of different diameters excised from U. prolifera, changes of the photosynthetic properties of cells during sporangia formation, and development of spores. The results suggested that disks less than 1.00 mm in diameter were optimal for the formation of sporangia, but there was a small amount of spore release in these. The highest percentage of area of spore release occurred in disks that were 2.50 mm in diameter. In contrast, sporangia were formed only at the cut edges of larger disks (3.00 mm, 3.50 mm, and 4.00 mm in diameter). Additionally, the majority of spores liberated from the disks appeared vigorous and developed successfully into new individuals. These results implied that fragments of the appropriate size from the U. prolifera thalli broken by a variety of factors via producing spores gave rise to the rapid proliferation of the seaweed under field conditions, which may be one of the most important factors to the rapid accumulation of the vast biomass of U. prolifera in the green tide that occurred in Qingdao, 2008.

Photosynthesis-Dependent Extracellular Ca2+ Influx Triggers an Asexual Reproductive Cycle in the Marine Red Macroalga Porphyra yezoensis

Asexual propagation to increase the number of gametophytic clones via the growth of asexual haploid spores is a unique survival strategy found in marine multicellular algae. However, the mechanisms regulating the asexual life cycle are largely unknown. Here, factors involved in the regulation of production and discharge of asexual spores, so-called monospores, are identified in the marine red macroalga Porphyra yezoensis. First, enhanced discharge of monospores was found by incubation of gametophytes in ASPMT1, a modified version of the previously established synthetic medium ASP12. Comparison of the compositions of ASPMT1 and our standard medium, ESL, indicated that the Ca2+ concentration in ASPMT1 was three times lower than that in ESL medium. Thus, we modified ASPMT1 by increasing its Ca2+ concentration, resulting in reduction of monospore discharge. These findings demonstrate the role of reduced Ca2+ concentrations in enhancing monospore production and release. Moreover, it was also observed that initiation of asexual life cycle required illumination, was repressed by DCMU, and was induced by a Ca2+ ionophore in the dark. Taken together, these results indicate that photosynthesis-dependent Ca2+ influx triggers the asexual life cycle by promoting the production and discharge of monospores in P. yezoensis.

Analysis of environmental factors and their effects on fungal spores in the atmosphere of a tropical urban area (San Juan, Puerto Rico)

In Puerto Rico, respiratory diseases affect a significant percentage of the population, and it is possible that the environmental factors unique to the island, such as easterly winds, dense vegetation, and high humidity, may increase the concentration of airborne biological particulates that could distress susceptible individuals. As most studies characterized fungal spores and pollen in temperate zones, we wanted to describe their concentrations in a tropical zone. The Allergenco® (MK3) spore trap was used to monitor airborne spores and pollen concentrations for 12 months starting on May 2005. During the length of the study, silicone grease-coated microscope slides captured 12 impacts daily, which were then stained with calcofluor and observed under the microscope with bright field and ultraviolet light. Atmospheric conditions were recorded with the Precision Weather Station®. Precipitation, dew point, and relative humidity promote the presence of fungal spores in San Juan throughout the year, with basidiospores being the most frequent. Spore concentrations were higher during the early morning hours all the year around. Wind and gusts were dispersal factors, and humidity and the dew point favored the release of spores into the atmosphere. In contrast to spores, pollens were not found to be affected by any of the meteorological factors and no distinctive patterns were found. Describing how airborne spores and pollens, many of which have allergenic potential, behave in the tropics, such as in San Juan, Puerto Rico, could be used to design preventive measures for the benefit of the sensitized population. Information about the presence and abundance of aeroallergens will assist in the diagnosis of allergic rhinitis and asthma on the island.

Spore Maturation and Release of Two Evergreen Macaronesian Ferns, Culcita macrocarpa and Woodwardia radicans, along an Altitudinal Gradient

Abstract The variables affecting spore phenology have been poorly studied in contrast with the abundant literature on leaf phenology. This paper deals with the influence of altitude and canopy cover on spore maturation and release of Culcita macrocarpa and Woodwardia radicans in the island of Sao Miguel, Azores. The study was conducted during one sporing season at three altitudes (400, 600, and 800 m). In both species spore maturation occurred in autumn and may be controlled by the previous accumulation of photosynthates. Spores were not released until late winter owing to a requirement for dry weather conditions. Dispersal took place later at higher altitude, due to lower temperature and higher humidity. This gradual liberation of spores along an altitudinal gradient is important for the endemic Azores bullfinch Pyrrhula murina (a bird that feeds on spores in winter), providing food over an extended period.

Anthrax prevention and treatment: utility of therapy combining antibiotic plus vaccine

The intentional release of anthrax spores in 2001 confirmed this pathogen's ability to cause widespread panic, morbidity and mortality. While individuals exposed to anthrax can be successfully treated with antibiotics, pre-exposure vaccination can reduce susceptibility to infection-induced illness. Concern over the safety and immunogenicity of the licensed US vaccine (Anthrax Vaccine Adsorbed (AVA)) has fueled research into alternatives. Second-generation anthrax vaccines based on purified recombinant protective antigen (rPA) have entered clinical trials. These rPA vaccines induce neutralizing antibodies that prevent illness, but the magnitude and duration of the resultant protective response is modest. Efforts are underway to bolster the immunogenicity of rPA by combining it with adjuvants and other immunostimulatory agents. Third generation vaccines are under development that utilize a wide variety of immunization platforms, antigens, adjuvants, delivery methods and routes of delivery to optimize the induction of a protective immunity. For the foreseeable future, vaccination will rely on first and second generation vaccines co-administered with immune adjuvants. Optimal post-exposure treatment of immunologically naive individuals should include a combination of vaccine plus antibiotic therapy.

Exploding a myth: the capsule dehiscence mechanism and the function of pseudostomata in Sphagnum

The nineteenth century air-gun explanation for explosive spore discharge in Sphagnum has never been tested experimentally. Similarly, the function of the numerous stomata ubiquitous in the capsule walls has never been investigated. Both intact and pricked Sphagnum capsules, that were allowed to dry out, all dehisced over an 8-12 h period during which time the stomatal guard cells gradually collapsed and their potassium content, measured by X-ray microanalysis in a cryoscanning electron microscope, gradually increased. By contrast, guard cell potassium fell in water-stressed Arabidopsis. The pricking experiments demonstrate that the air-gun notion for explosive spore discharge in Sphagnum is inaccurate; differential shrinkage of the capsule walls causes popping off the rigid operculum. The absence of evidence for a potassium-regulating mechanism in the stomatal guard cells and their gradual collapse before spore discharge indicates that their sole role is facilitation of sporophyte desiccation that ultimately leads to capsule dehiscence. Our novel functional data on Sphagnum, when considered in relation to bryophyte phylogeny, suggest the possibility that stomata first appeared in land plants as structures that facilitated sporophyte drying out before spore discharge and only subsequently acquired their role in the regulation of gaseous exchange.

Bacillus cereus Spores Release Alanine that Synergizes with Inosine to Promote Germination

BackgroundThe first step of the bacterial lifecycle is the germination of bacterial spores into their vegetative form, which requires the presence of specific nutrients. In contrast to closely related Bacillus anthracis spores, Bacillus cereus spores germinate in the presence of a single germinant, inosine, yet with a significant lag period.Methods and FindingsWe found that the initial lag period of inosine-treated germination of B. cereus spores disappeared in the presence of supernatants derived from already germinated spores. The lag period also dissipated when inosine was supplemented with the co-germinator alanine. In fact, HPLC-based analysis revealed the presence of amino acids in the supernatant of germinated B. cereus spores. The released amino acids included alanine in concentrations sufficient to promote rapid germination of inosine-treated spores. The alanine racemase inhibitor D-cycloserine enhanced germination of B. cereus spores, presumably by increasing the L-alanine concentration in the supernatant. Moreover, we found that B. cereus spores lacking the germination receptors gerI and gerQ did not germinate and release amino acids in the presence of inosine. These mutant spores, however, germinated efficiently when inosine was supplemented with alanine. Finally, removal of released amino acids in a washout experiment abrogated inosine-mediated germination of B. cereus spores.ConclusionsWe found that the single germinant inosine is able to trigger a two-tier mechanism for inosine-mediated germination of B. cereus spores: Inosine mediates the release of alanine, an essential step to complete the germination process. Therefore, B. cereus spores appear to have developed a unique quorum-sensing feedback mechanism to monitor spore density and to coordinate germination.

Three microsporidian pathogens infecting Lymantria dispar larvae do not differ in their success in horizontal transmission

AbstractWe quantified horizontal transmission of three microsporidian pathogens, Endoreticulatus schubergi, Nosema lymantriae and Vairimorpha disparis that infect Lymantria dispar larvae in an experiment using caged, potted oak plants. Despite marked differences in the modes of spore release from infectious hosts, no significant differences in the transmission success to uninfected, susceptible test hosts were ascertained between the tested microsporidian species. The density of initially inoculated larvae and the exposure period, on the other hand, did influence the number of infected test larvae. Depending on the density of inoculated larvae (10%, 30% or 50%), between 0% and 26% of the test larvae became infected with one of the three tested microsporidian pathogens after an exposure period of 6 days. When the exposure period was 12 days, between 11% and 76% of the test larvae became infected.

First report of fern ( Culcita macrocarpa) spore consumption by a small mammal ( Apodemus sylvaticus)

Few vertebrates are known to consume ferns regularly. Several species of mammals consume leaves to some extent but the consumption of fern spores is much rare. In Galicia (Northwest Spain) we studied the seasonal variation in the consumption of Culcita macrocarpa fertile leaves (i.e. with spores) in two populations (Capelada and Eume), assessed whether consumption rate increased with fern population size, and evaluated whether the consumer was a spore predator or a spore disperser. Consumption began in December and finished by mid February, and occurred before spore release, which happened later in Capelada than in Eume, probably influenced by differences in altitude. The consumer was identified as Apodemus sylvaticus by DNA analysis of its droppings and by capture of live animals. Throughout Galicia there was a significant increase in fern consumption rate as the population size of C. macrocarpa increased. Germination tests from droppings were carried out in 14 dishes but only in two dishes 1% and 0.3% of the spores germinated. Our results suggest that woodmouse can disperse spores of C. macrocarpa, although most of the spores were digested.

Protecting against Future Shock — Inhalational Anthrax

In a world filled with pressing unmet medical needs, why would a physician want to protect against a disease that is rarely seen? Part of the answer can be deduced from the events of the fall of 2001. The deliberate release of anthrax spores on unsuspecting U.S. citizens in the wake of September 11 unsettled Americans who were already concerned about the weaponization of smallpox, Ebola and Marburg viruses, and other pathogens. The subsequent arrival of the highly pathogenic avian influenza virus, together with the recent swine influenza epidemic, has further underscored our vulnerability to infectious diseases, both deliberate and . . .

Zoospores of three Arctic laminariales under different UV radiation and temperature conditions: exceptional spectral absorbance properties and lack of phlorotannin induction.

Phlorotannins have often been considered to act as UV-protective compounds in zoospores of brown algae. However, only the absorption characteristics of zoospores under UV exposure have been determined and no data are available on the actual content of phlorotannins or on temperature-UV interactions. Therefore, we determined the absorbance spectra and the phlorotannin contents in zoospore suspensions of three Arctic species (Saccharina latissima, Laminaria digitata, Alaria esculenta), and in the media surrounding zoospores after exposure to different radiation (400-700, 320-700, 295-700 nm) and temperature (2-18 degrees C) conditions for 8 h. Absorption typical of phlorotannins with a maximum at 276 nm was monitored in zoospore suspensions as well as in the media surrounding zoospores, but the results depended strongly on radiation treatments and on zoospore densities. Surprisingly, the content of UV-absorbing phlorotannins subsequent to different exposures did not change in any of the three species. The observed exceptional absorption properties could, therefore, not be related to phlorotannin contents. These findings are discussed in light of a strong phlorotannin investment from sporophytes during spore release and a minor UV-protective role of phlorotannins for zoospores of Arctic kelp species.

Design and evaluation of a new device for fungal spore aerosolization for laboratory applications

Fungi have significant health effects varying from serious allergic reactions from inhalation to toxic effects and even fatal infections. Indoor and outdoor sampling may identify potentially contaminated environments, but sampling techniques need refining to set risk levels regarding occupational exposure or to assess and analyse sudden outbreaks of fungi. As little is known of the sporulation and dispersal dynamics of fungi, we have experimented with aerosolizing fungal spores from cultures grown in standard 9 cm Petri dishes for 3–10 h using a new device that incorporates vibration. We evaluated the effect of the air flow and frequency on a quantity and pattern of spores aerosolized. Frequency had positive, negative or no effect. Positive quantitative effects were noted in Aspergillus versicolor at 50 Hz, in Aspergillus niger at 400 Hz and at 100–400 Hz in Rhizopus. Aerosolization of Aspergillus species dropped significantly in the first 20 min and then stabilised for 2.5–3 h. After this time period, the generation process became highly unstable with large quantities of small particles produced. It could be explained by appearance of cracks on the nutrient surface due to desiccation with corresponding release of particles of nutrient to the air carrier. For Rhizopus, the initial steep decrease in particle generation for the first 20 min of the process was followed by quite stable spore production for the following 10 h of process operation. There were no cracks observed on the nutrient surface for the entire 10 h operation of the device. The air flow also affects the efficiency of the spore release. It was found that increase in the air flow was associated with more efficient sporulation from the nutrient dish. On the other hand, the size distribution curve of the airborne spores produced at higher air flows was correspondingly slightly shifted towards larger sizes, which is related to less efficient loosening of spores and corresponding increase in concentration of clumps consisting of more than one spore. Also, it was found that incubation of fungal cultures for extended periods (2–6 weeks) led towards production of larger numbers of airborne fungal spores.