Spore Longevity Research Articles

Bryophyte Spores Tolerate High Desiccation Levels and Exposure to Cryogenic Temperatures but Contain Storage Lipids and Chlorophyll: Understanding the Essential Traits Needed for the Creation of Bryophyte Spore Banks.

Understanding the desiccation and freezing tolerance of bryophyte spores is vital to explain how plants conquered land and current species distribution patterns and help to develop efficient ex situ conservation methods. However, knowledge of these traits is scarce. We investigated tolerance to drying (at 15% relative humidity [RH] for two weeks) and freezing (1 h exposure to liquid nitrogen) on the spores of 12 bryophyte species (23 accessions) from the UK. The presence of storage lipids and their thermal fingerprint, and the levels of unfrozen water content, were determined by differential scanning calorimetry (DSC). The presence of chlorophyll in dry spores was detected by fluorescence microscopy. All species and accessions tested tolerated the drying and freezing levels studied. DSC suggested that 4.1–29.3% of the dry mass is storage lipids, with crystallization and melting temperatures peaking at around −30 °C. Unfrozen water content was determined <0.147 g H2O g−1 dry weight (DW). Most of the spores investigated showed the presence of chlorophyll in the cytoplasm by red autofluorescence. Bryophyte spores can be stored dry at low temperatures, such as orthodox seeds, supporting the creation of bryophyte spore banks. However, the presence of storage lipids and chlorophyll in the cytoplasm may reduce spore longevity during conventional storage at −20 °C. Alternatively, cryogenic spore storage is possible.

Soil legacy determines arbuscular mycorrhizal spore bank and plant performance in the low Arctic

Human impact is rapidly changing vegetation globally. The effect of plant cover that no longer exists in a site may still affect the development of future vegetation. We focused on a little studied factor—arbuscular mycorrhizal (AM) fungus spore bank—and its effect on three test plant species. In a low Arctic field site, plots were maintained for 6 years, devoid of any vegetation or with a Solidago virgaurea monoculture cover. We analysed the AM fungal morphospecies composition and identified 21 morphospecies in the field plots. The AM morphospecies community was dominated by members of Acaulosporaceae. Monoculturing under low Arctic field conditions changed the soil AM spore community, which became dominated by Glomus hoi. We tested the soil feedback in the greenhouse and grew Solidago virgaurea, Potentilla crantzii and Anthoxanthum odoratum in the field soils from the plots without plant cover, covered with Solidago virgaurea or with intact vegetation. Our results suggest that monoculturing resulted in improved N acquisition by the monocultured plant species Solidago virgaurea which may be related to the AM fungus community. Our results show that a rich community of AM fungus spores may remain viable under field conditions for 6 years in the low Arctic. Spore longevity in field soil in the absence of any host plants differed among AM fungus species. We suggest that AM fungus spore longevity be considered an AM fungal life-history trait.

Anaerobic nitrate respiration in the aerobe Streptomyces coelicolor A3(2): helping maintain a proton gradient during dormancy.

Respiratory nitrate reductases (Nar) catalyse the reduction of nitrate to nitrite, coupling this process to energy conservation. The obligate aerobic actinobacterium Streptomyces coelicolor synthesizes three Nar enzymes that contribute to maintenance of a membrane potential when either the mycelium or the spores become hypoxic or anoxic. No growth occurs under such conditions but the bacterium survives the lack of O2 by remaining metabolically active; reducing nitrate is one means whereby this process is aided. Nar1 is exclusive to spores, Nar2 to vegetative mycelium and Nar3 to stationary-phase mycelium, each making a distinct contribution to energy conservation. While Nar2 and Nar3 appear to function like conventional menaquinol oxidases, unusually, Nar1 is completely dependent for its activity on a cytochrome bcc-aa 3 oxidase supercomplex. This suggest that electrons within this supercomplex are diverted to Nar1 during O2 limitation. Receiving electrons from this supercomplex potentially allows nitrate reduction to be coupled to the Q-cycle of the cytochrome bcc complex. This modification likely improves the efficiency of energy conservation, extending longevity of spores under O2 limitation. Knowledge gained on the bioenergetics of NO3 - respiration in the actinobacteria will aid our understanding of how many microorganisms survive under conditions of extreme nutrient and energy restriction.

An Improved Evans Blue Staining Method for Consistent, Accurate Assessment of Plasmodiophora brassicae Resting Spore Viability.

Clubroot caused by Plasmodiophora brassicae is an important disease of brassica crops. The use of vital stains to determine the viability of P. brassicae resting spores can provide useful information regarding spore longevity, inoculum potential, or the efficacy of antimicrobial treatments. Evans blue is one example of a vital stain that has been reported to differentially stain viable and nonviable resting spores. Some previously published protocols using Evans blue to stain P. brassicae resting spores have not provided accurate or consistent results. In this study, we modified the Evans blue method by increasing the staining time to 8 h or more and evaluated P. brassicae resting spores after heat treatment at various combinations of temperature and time. Extending staining times significantly increased the numbers of stained resting spores up to 7 h, after which the numbers of stained spores did not change significantly (R2 = 96.88; P ≤ 0.001). The accuracy of the modified method to discriminate viable and nonviable spores was evaluated in repeated experiments and by comparing the staining data with those derived from inoculation assays and propidium monoazide quantitative PCR (qPCR). The results demonstrated that the modified Evans blue staining method improved the accuracy and consistency of measurement of P. brassicae resting spore viability. Additionally, it was equivalent to the qPCR method for differentiating viable and nonviable spores (R2 = 99.84; P ≤ 0.001) and confirmed in canola infection bioassays.

Oxygen-deficiency and allelochemicals affect Sphagnum spore persistence in peatlands

To test the effects of characteristic ecological gradients in peatlands including oxygen-deficiency and allelopathy on Sphagnum spore persistence. We determined the initial viability of Sphagnum spores and then stored the spores for 60 days, either dry, in ultrapure water, peatland surface water or Sphagnum water leachate (the latter two solutions rich in allelochemicals from Sphagnum). We varied oxygen concentration by injecting air at three different concentrations during the storage experiment. After retrieval from experimental storage, spore germinability index was assessed. Germinability index after air injection was lower than under oxygen-deficiency. Germinability index in the peatland surface water and Sphagnum leachate water was higher than in ultrapure water, under oxygen-deficiency. Overall, dissolved oxygen and high pH negatively affected spore germinability and, consequently, viability. These results indicate that once dispersed onto bryophyte substrates or waterlogged hollows, Sphagnum spores can maintain viability better than when exposed to dry conditions or in water without allelochemicals. Extreme longevity of Sphagnum spores may be attributed to the oxygen-deficient, waterlogged and acidic Sphagnum-dominated peatland habitat with allelopathic substrates.

Photo-oxidation modulates green fern spore longevity during dry storage

Desiccation tolerance and longevity of plant propagules in the dry state have significant implications for biotechnological applications. In this study fern spores were used as a unicellular model to characterize some of the mechanisms of ageing during dry storage of plant propagules (at relative humidity ca. 15%). More specifically, we compared the potential relationships among indicators of photo-oxidative stress and spore viability during dry storage between green (chlorophyllous) spores of Todea barbara and non-green spores of Christella dentata. Green spores stored under the light aged faster than those stored in the dark, and faster than light- and dark-stored non-green spores of C. dentata. This rapid ageing in light-stored green spores was associated with significantly lower antioxidant activity (relative to time zero and dark-stored spores) during storage, and a burst of hydrogen peroxide during the latter stages of storage, which was not a feature of dark-stored spores. We attribute these signs of enhanced oxidative-stress mediated ageing in light-stored spores to photo-oxidative processes, similar to those described in other homoiochlorophyllous organisms. Additionally, high antioxidant activity and low levels of reactive oxygen species in green spores compared with non-green spores suggests differing mechanisms of coping with life in the dry state.

Longevity of light- and dark-colored basidiospores from saprotrophic mushroom-forming fungi

ABSTRACTFungi can produce resistant propagules that may last for decades. Basidiospores from ectomycorrhizal fungi had been experimentally shown to last for at least 6 yr, but there are few reports on the longevity of saprotrophic members of mushroom-forming fungi. Here, the author shows evidence of spore longevity of these fungi by collecting, drying, storing, and germinating these spores over time. Results showed that dark-colored spores have a much-extended longevity as compared to light-colored spores. Dark-colored spores of some species are viable to at least 2.8 yr, whereas light-colored spores are generally viable for a much shorter period of time. The author proposes that mushroom-forming basidiomycete fungi employ two different ecological strategies: one with extended longevity that allows for long-distance dispersal, and the other takes advantage of optimal conditions that support both mushroom formation, basidiospore dispersal, and germination locally.

Mycorrhizae, invasions, and the temporal dynamics of mutualism disruption

Summary An increasingly recognized impact of plant invaders is the disruption of positive interactions between native plants and their belowground mutualistic mycorrhizal fungi. We reviewed 112 studies from 61 publications that report invader impacts on mycorrhizal fungi. We describe emerging patterns on the frequency of negative, neutral and positive invader effects on mycorrhizal fungal abundance, richness and community composition, and we evaluate how these outcomes vary with invasion age. We also describe the evidence for three mechanisms of disruption: (1) plant‐plant competition that alters host quantity or quality (2) changes in soil properties such as nutrient availability and (3) allelopathy. Invaders can disrupt native mutualisms if they are non‐mycorrhizal, associate with a different type of mycorrhiza, or associate with different taxa of the same type of mycorrhiza as the native plants. Invaders that enrich soil nutrients can cause declines in mycorrhizal abundance, shifts in fungal community composition, and cause native plants to reduce their dependence on mycorrhizas. Invaders that produce allelopathic compounds cause mycorrhizal abundance to decrease and alter community composition because of variation in the sensitivity of different fungi to toxins. While the evidence for disruption of the mycorrhizal mutualism with invasion is strong, temporal patterns have not yet emerged from the literature. Invasion age was not clearly associated with extent of disruption, and the timing of recovery following invader removal was highly variable. Differences in the biology of native and invasive plants, their interactions with mycorrhizal fungi and the surrounding landscape contributed to this variation. Synthesis. Our systematic review suggests that invaders frequently decrease mycorrhizal abundance and alter fungal community composition while only occasionally affecting fungal species richness. The development of invader impacts, as well as the restoration of native communities after invader removal, are influenced by a suite of plant, fungal and environmental traits that change over time. However, few studies have examined the temporal dynamics of mycorrhizal disruption, and results are variable. Future research should focus on the temporal scale of mutualism disruption while considering plant phylogenetics and demography, fungal functional traits such as spore longevity and dispersal, and soil chemistry.

Determination of spore longevity and viability of Nosema apis and Nosema ceranae according to storage conditions

Abstract Honey bee colonies are often infected with Nosema apis and Nosema ceranae which cause adult honey bee disease called nosemosis. All honey bee colony members can be infected with these species. In addition, it is claimed to be the main cause of honey bee winter losses in many countries. Nosema spores are expected to resistant the environmental conditions and their infectivity continues for a long time because of long-term durability of fungal spores. In this study, the viability of Nosema spores were investigated in terms of storage situations under laboratory conditions. Honey bee samples that were collected from apiaries in 2011 were investigated to detect the presence of Nosema species with real-time PCR amplification studies. After determination of Nosema species, each sample was divided in two groups. One of these groups was used to find Nosema spore concentration. Nosema solutions were divided and stored at both -20°C and +4°C. The spore concentration was measured every year in the period 2011-2015. Other group of honey bee samples was also stored at -20°C and every year was used for Nosema spore counting. Furthermore, it was examined the infectivity of Nosema spores with sugar solutions which obtained each sample using cage experiment techniques. According to results, when we compare the solutions annually, there is no change at Nosema spore concentration of the solution in -20°C and honeybee samples in -20°C. But reduction was seen at Nosema spore concentration of the solution in +4°C. Nosema spore infectivity tests revealed that infectivity of Nosema spores has not changed significantly between 2011 and 2015. This is the first time mixed Nosema spores found more infective than one-type spore after prolonged exposure to different conditions.

长白山哈泥泥炭地丘间生境泥炭藓孢子的寿命

PDF HTML阅读 XML下载 导出引用 引用提醒 长白山哈泥泥炭地丘间生境泥炭藓孢子的寿命 DOI: 10.5846/stxb201306181731 作者: 作者单位: 东北师范大学,东北师范大学,东北师范大学 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金(30700055, 40971036, 41273147); 中央高校基本科研业务费专项资金(11GJHZ003) Longevity of sphagnum spores in the hollow habitats of Hani Peatland, Changbai Mountains Author: Affiliation: Northeast Normal University,Northeast Normal University,Northeast Normal University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:长寿有性繁殖体对于植物种群的长存具有重要意义,迄今,泥炭地苔藓植物孢子长寿性研究还很少。在长白山哈泥泥炭地钻取丘间表层泥炭样品,测定泥炭腐殖化度和烧失量,逐层提取和培养泥炭藓孢子,研究埋藏时间对孢子萌发的影响。结果表明,丘间泥炭藓孢子埋藏环境中,随着埋深的增加即埋藏年限的增加,泥炭腐殖化度和烧失量总体上分别呈现增加和递减的趋势,而地层泥炭藓孢子萌发率呈现直线递减的规律,但在埋藏近150余年后孢子萌发率仍可达40%。研究进一步证明泥炭藓具有长期持久孢子库,根据推算,泥炭地丘间埋藏环境中,泥炭藓孢子最大寿命可超过400a。 Abstract:Longevous sexual propagules are of great importance for persistence of plant populations. In natural environment, Sphagnum spores have potential to germinate and regenerate. They may play an important role in maintaining population persistence of Sphagnum when great natural or man-made disturbance happens. However, quite few studies about spore longevity of peatland bryophytes have been reported so far. In Hani Peatland of the Changbai Mountains, we took peat cores in hollow habitats, determined peat humification degree and ignition loss and extracted the spores of Sphagnum from the peat cores layer by layer. We cultivated the spores, to investigate the effect of burial time on spore germination rate. In the burial environment of hollows for Sphagnum spores, with the increase of depth namely burial time, peat humification degree and ignition loss generally showed a trend of increase and decrease, respectively. The germination rate of Sphagnum spores decreases linearly, but it can still reach 40% after the spores were buried for more than 150 years. Our study further proves that there are long-term persistent spore banks in peatlands. If we define the maximum longevity of spores as the time that when germination rate of spores is 1% in the burial environment, the maximum longevity for Sphagnum spores can be older than 400 years. The longevity mechanism of Sphagnum spores may be related with the special burial environment of peatlands. It is necessary to carry out experiments to test effects of environment factors such as hydrology, water chemistry and even microbiological diversity on spore viability in the future. 参考文献 相似文献 引证文献

The persistence and germination of fern spores in fire-prone, semi-arid environments

In addition to population regeneration, the spore phase provides ferns with a capacity for dispersal through space and time (if spores are able to survive for long periods), and buffers their populations against environmental extremes. Inhabiting dry and fire-prone environments provides specific challenges to ferns, and the traits of fern spores in relation to these challenges are not well understood. Their shallow, dense and fibrous root networks mean that the loss or establishment of fern populations in disturbed ecosystems may influence soil stability, and indicate a keystone role in ecosystem function and ecological restoration. Here, we examine the requirements for, and limits of, spore persistence and germination of three Cheilanthes Syn.Fil. (Pteridaceae) species, namely, optimal conditions for spore germination and prothallial growth, sensitivity to temperature extremes and spore longevity. Viability of fresh spores was assessed following exposure to temperature extremes (–20 to 250°C) or after incubation at a range of temperatures (10−35°C) and in light or dark conditions. Viability of spores from herbarium voucher specimens was also assessed, covering 3–65 years of storage. Maximal germination occurred among spores incubated between 20°C and 30°C in light. Further temperature variation within this range resulted in a ×10 difference in prothallial size. Germination was unaffected by 10 min of exposure to temperatures up to 100°C, but was reduced after exposure to temperatures of −20°C and 110°C. Germination of herbarium-stored spores demonstrated longevity of up to 15 years. This longevity, combined with high spore density in field soils (including at depth to at least 10 cm), very high germination under ideal conditions, and microscopic size, describes a disturbance-mediated propagule persistence strategy. Spores are non-persisting and will germinate if exposed to light and water, but do persist if buried. Germinable spore can be found 5 cm below the soil surface, and can persist for at least 15 years, but the light requirement for germination means that persistent spores can achieve germination only if exhumed. Elucidating these traits reveals a unique pathway for plant persistence, and contributes to the development of the restoration capacity of arid-environment ferns.

Fern Spore Longevity in Saline Water: Can Sea Bottom Sediments Maintain a Viable Spore Bank?

Freshwater and marine sediments often harbor reservoirs of plant diaspores, from which germination and establishment may occur whenever the sediment falls dry. Therewith, they form valuable records of historical inter- and intraspecific diversity, and are increasingly exploited to facilitate diversity establishment in new or restored nature areas. Yet, while ferns may constitute a considerable part of a vegetation’s diversity and sediments are known to contain fern spores, little is known about their longevity, which may suffer from inundation and - in sea bottoms - salt stress. We tested the potential of ferns to establish from a sea or lake bottom, using experimental studies on spore survival and gametophyte formation, as well as a spore bank analysis on sediments from a former Dutch inland sea. Our experimental results revealed clear differences among species. For Asplenium scolopendrium and Gymnocarpium dryopteris, spore germination was not affected by inundated storage alone, but decreased with rising salt concentrations. In contrast, for Asplenium trichomanes subsp. quadrivalens germination decreased following inundation, but not in response to salt. Germination rates decreased with time of storage in saline water. Smaller and less viable gametophytes were produced when saline storage lasted for a year. Effects on germination and gametophyte development clearly differed among genotypes of A. scolopendrium. Spore bank analyses detected no viable spores in marine sediment layers. Only two very small gametophytes (identified as Thelypteris palustris via DNA barcoding) emerged from freshwater sediments. Both died before maturation. We conclude that marine, and likely even freshwater sediments, will generally be of little value for long-term storage of fern diversity. The development of any fern vegetation on a former sea floor will depend heavily on the deposition of spores onto the drained land by natural or artificial means of dispersal.

49. Interactions between water and triacylglycerols may explain faster aging rates in stored germplasm at low temperatures

Longevity of orthodox (desiccation tolerant) seeds, pollen and fern spores characteristically increases with decreasing storage temperature. We have discovered numerous seed and fern spore species that age faster when stored in the freezer near −20 °C compared to storage at higher or lower temperatures. Seeds exhibiting this temperature anomaly are considered to be intermediate between orthodox and recalcitrant physiologies. Intermediate traits are often associated with high proportions of saturated fatty acids within the triacylglycerols (TAG), accumulated into cells as food reserves. TAG high in saturated fatty acids crystallize and melt within the temperature range of the observed longevity anomalies and we have hypothesized a link between TAG phase change and increased damage to germplasm cells. Damage is exacerbated as water content within stored seeds and fern spores increases from near 5% to about 12%. These observations have led us to hypothesize that damage results from an interaction between TAG, water, temperature and time. The purpose of this research is to explore the extent and significance of possible interacting factors on the viability of stored germplasm. Our work begins with characterizing the kinetics of TAG and water phase changes in peanut ( Arachis hypogaea ) and papaya ( Carica papaya ) seeds equilibrated to different water contents and stored at temperatures between −5 and − 80°C. Water and TAG phase was measured using a Perkin Elmer Differential Scanning Calorimeter. Cytoplasm ultra-structure was visualized without chemical fixatives using low temperature scanning electron microscopy (cryo-SEM) performed with a Zeiss DSN 960 scanning microscope equipped with a Cryotrans CT-1500 cold plate (Oxford, UK). The time dependency of phase changes was assessed over a 3 week period. We report that TAG crystallization in seeds is independent of water content and occurs over several days. The amount of water that freezes in seeds increases with storage duration in a manner consistent with TAG crystallization kinetics.

Fast Real-Time PCR assay for detection of Tetramicra brevifilum in cultured turbot

Global aquaculture production of turbot has rapidly increased worldwide in the last decade and it is expected to have even bigger growth in the next years due to new farms operating. The losses caused by pathogen infections have grown at the same time as the production of this species. Parasitological infections are among the main relevant pathologies associated with its culture and produce serious losses in aquaculture, reduce the growth rate in fish and may lead to unmarketable fish due to skeletal muscle abnormalities in cases with high intensity of infection. The microsporidian parasite Tetramicra brevifilum causes severe infections and generates major losses in farmed turbot. Infections are difficult to control due to spore longevity and its direct transmission. To facilitate the infection management, an effective tool for fast detection and identification of T. brevifilum is needed. This study provides a molecular methodology of fast Real-Time PCR for T. brevifilum detection to the aquaculture industry, useful for routine control of T. brevifilum at turbot farms. The method is characterized by its high specificity and sensitivity, and it can be applied to cultured turbot for parasite detection regardless of the life-cycle stage of the pathogen or the infection intensity.

Stayin' alive: survival of mycorrhizal fungal propagules from 6-yr-old forest soil

Spores and sclerotia are the main propagules that allow fungi to persist through unfavorable conditions and disperse into new environments. Despite their importance, very little is known about their longevity and dormancy, especially in ectomycorrhizal fungi. To assess the viability of ectomycorrhizal fungal spores in forest soil, we collected and buried non-sterile forest soil, in pots, in the field distant from an inoculum source. After 6 yr, a subset of this soil was assayed for viable spores by baiting the fungi with Bishop pine (Pinus muricata) seedlings. Our results show that the three most frequent colonizers in year 1 continued to colonize significant percentages of seedlings in year 6: Wilcoxina mikolae (77 %), Rhizopogon vulgaris (13 %) and Suillus brevipes (9 %). While three species that colonized low percentages of seedlings in year 1, Suillus pungens (1 %), Rhizopogon salebrosus (2 %), and Thelephora terrestris (5 %) were not recovered in year 6. Laccaria proxima, a species not seen in year 1, was recovered on a single seedling in year 6. This is the first report of long-term survival of S. brevipes and W. mikolae. Our results reveal a more complete picture of ectomycorrhizal fungal spore longevity in soil spore banks.

Effects of temperature and desiccation on ex situ conservation of nongreen fern spores

Fern spores are unicellular and haploid, making them a potential model system to study factors that regulate lifespan and mechanisms of aging. Aging rates of nongreen spores were measured to compare longevity characteristics among diverse fern species and test for orthodox response to storage temperature and moisture. Aging of spores from 10 fern species was quantified by changes in germination and growth parameters. Storage temperature ranged from ambient room to -196°C (liquid nitrogen); spores were dried to ambient relative humidity (RH) or using silica gel. Survival of spores varied under ambient storage conditions, with one species dying within a year and two species having greater than 50% survival after 3 years. Few changes in germination or growth were observed in spores stored at either -80°C or -196°C over the same 3-yr study period. Spores stored at -25°C aged anomalously quickly, especially those dried to ambient RH or subjected to repeated freeze-thaw cycles. Spore longevity is comparable to orthodox seed longevity under ambient storage conditions, with wide variation among species and shelflife extended by drying or cooling. However, faster aging during freezer storage may indicate a similar syndrome of damage experienced by seeds categorized as "intermediate". The damage is avoided by storage at -80°C or liquid nitrogen temperatures, making cryoconservation an effective and broadly applicable tool to extend fern spore longevity. The study demonstrates that spore banks are a feasible approach for ex situ conservation of this important plant group.

Identifying experimental surrogates for Bacillus anthracis spores: a review.

Bacillus anthracis, the causative agent of anthrax, is a proven biological weapon. In order to study this threat, a number of experimental surrogates have been used over the past 70 years. However, not all surrogates are appropriate for B. anthracis, especially when investigating transport, fate and survival. Although B. atrophaeus has been widely used as a B. anthracis surrogate, the two species do not always behave identically in transport and survival models. Therefore, we devised a scheme to identify a more appropriate surrogate for B. anthracis. Our selection criteria included risk of use (pathogenicity), phylogenetic relationship, morphology and comparative survivability when challenged with biocides. Although our knowledge of certain parameters remains incomplete, especially with regards to comparisons of spore longevity under natural conditions, we found that B. thuringiensis provided the best overall fit as a non-pathogenic surrogate for B. anthracis. Thus, we suggest focusing on this surrogate in future experiments of spore fate and transport modelling.

Anthrax: Public health risk in india and socio-environmental determinants

Zoo authorities of Central Indian State of Chattisgarh reported a hyena suffering from the fatal anthrax disease in Nandanvan zoo in capital city Raipur. After laboratory confirmation of anthrax, the zoo was closed for 15 days as precautionary measure. According to the veterinarians of the zoo, all symptoms of anthrax were found in one of the hyenas. The Forest department officials decided to vaccinate animals within the 5 km radius of zoo to contain the disease. All employees of Nandanvan zoo had been put on prophylactic antibiotic medicine.(1) The report of death of a hyena due to anthrax in the state of Chattisgarh in India during June 2007 was very disturbing and was unusual occurrence by any standards. Chattisgarh state has never reported anthrax case either in animal or in humans. Anthrax is generally an epizootic disease which infects and kills herbivorous animals e.g. cattle, sheep, and goat.(2) Cattle get mostly infected by eating vegetations contaminated by spores. Elephants have been known to die of anthrax in north-east. They and other herbivores develop bacteriamic phase followed by death. So do poor humans. Occasionally dogs, horses, etc. are also found to be infected but are rarely fatal in them. Terminally ill animals tend to bleed from the nose, mouth, and bowel, thereby contaminating soil or water places with B. anthracis that can subsequently sporulate and persist in the environment. On further literature review, the Chattisgarh incident turns out to be the first case of death of non-herbivorous animal like hyena dying due to anthrax in India.(3) This event has a great epidemiological as well as public health significance. The reports of anthrax infection in hyena leading to death is a pointer towards the larger fact that the anthrax bacteria are in circulation in Chattisgarh, also it is a matter of concern from public health point of view, as once anthrax affected, the locale is always anthrax prone on account of longevity of viable spores lasting many decades. From public health point of view, it is very important that Chattisgarh should step up their mechanism for animal screening for anthrax. Since Chattisgarh never had history of anthrax, capacities and skills for the same need to be instituted. Once anthrax is fully established as enzootic disease in a region, it is only a matter of time before zoonotic transmission begin and human case of anthrax begin to appear posing as big public health problem. The case in point is Orissa, where anthrax is an endemic disease and already a major public health problem of Orissa; 14 out of 30 revenue districts in the state have witnessed outbreaks of anthrax as many as 61 times during the last 10 years affecting 750 people of which 418 had died.(4) The anthrax outbreaks are an annual phenomenon Orissa. With good forest cover, the soil being highly organic in with good moisture to support anthrax spores. Due to scanty agriculture, tribals mainly depend on forest for livelihood. Risk of infection increases due to anthrax spores in the wild. Outbreaks of anthrax in these indigenous populations very often occur as food poisoning following consumption of contaminated cattle meat. Tribals for that matter, any given community, in these states particularly if underprivileged, eat carcass of dead animals. Such people are vulnerable. Even if they do not eat, if they de-skin carcasses of infected animals, they are also vulnerable for anthrax infection. Anthrax is known to occur generally in underdeveloped regions.(5) Ecologically speaking, from vulnerability point of view, Chattisgarh shows striking parallels and Orissa, as far as potential proneness and risk of anthrax outbreaks in the human population in the coming years: Chattisgarh and Orissa rank almost similar on human development indices (HDIs); Like Orissa, Chattisgarh has very high concentration of tribal population (>35%); Both the states have extensive forest cover; The indigenous population of both these states depend less on agriculture and more on forest and animal produce for food; Overwhelming majority of people in both these states live below the poverty line. Both the states have poor public health infrastructure. This is the perfect amalgamation and interface of risk factors that are conducive for zoonotic transmission of anthrax to the human population. Hence the probability of occurrence of anthrax outbreak in the human population would increase on logarithmic scale, each time an episode of anthrax detected in animal population in a state like Chattisgarh. So, epizootology and epidemiology should be both applied not only for anthrax, but for every zoonotic disease, hence the importance of veterinary and doctors putting heads together.

Water properties in fern spores: sorption characteristics relating to water affinity, glassy states, and storage stability

Ex situ conservation of ferns may be accomplished by maintaining the viability of stored spores for many years. Storage conditions that maximize spore longevity can be inferred from an understanding of the behaviour of water within fern spores. Water sorption properties were measured in spores of five homosporeous species of ferns and compared with properties of pollen, seeds, and fern leaf tissue. Isotherms were constructed at 5, 25, and 45 degrees C and analysed using different physicochemical models in order to quantify chemical affinity and heat (enthalpy) of sorption of water in fern spores. Fern spores hydrate slowly but dry rapidly at ambient relative humidity. Low Brunauer-Emmet-Teller monolayer values, few water-binding sites according to the D'Arcy-Watt model, and limited solute-solvent compatibility according to the Flory-Huggins model suggest that fern spores have low affinity for water. Despite the low water affinity, fern spores demonstrate relatively high values of sorption enthalpy (DeltaH(sorp)). Parameters associated with binding sites and DeltaH(sorp) decrease with increasing temperature, suggesting temperature- and hydration-dependent changes in volume of spore macromolecules. Collectively, these data may relate to the degree to which cellular structures within fern spores are stabilized during drying and cooling. Water sorption properties within fern spores suggest that storage at subfreezing temperatures will give longevities comparable with those achieved with seeds. However, the window of optimum water contents for fern spores is very narrow and much lower than that measured in seeds, making precise manipulation of water content imperative for achieving maximum longevity.

History of science – spores.

Bacterial endospores were first studied 130 years ago by Cohn in 1876 and independently by Koch in the same year. Although spore dormancy and resistance have been much studied since then, questions still remain concerning the basic mechanisms and the kinetics of heat inactivation in particular. Likewise, the extreme dormancy and longevity of spores was recognized early on and later greatly extended but still evade complete understanding. Evidence has accumulated for the involvement of specific spore components such as calcium, dipicolinic acid, small acid soluble proteins in the core and peptidoglycan in the cortex. Involvement of physical factors too, such as the relative dehydration of the core, maybe in a high-viscosity state or even in a glassy state, has added to appreciation of the multicomponent nature of dormancy and resistance. Spore-former morphology formed the basis for early classification systems of sporeformers from about 1880 and consolidated in the mid-1900s, well prior to the use of modern genetic procedures. With respect to sporulation, groundbreaking sequence studies in the 1950s provided the basis for later elucidation of the genetic control widely relevant to many cell differentiation mechanisms. With respect to the breaking of dormancy (activation and germination), the elucidation of mechanisms began in the 1940s following the observations of Hills at Porton who identified specific amino acid and riboside 'germinants', and laid the basis for the later genetic analyses, the identification of germinant receptor genes and the elucidation of key germination reactions. The nonexponential nature of germination kinetics has thwarted the development of practical Tyndallization-like processing. So inactivation by heat remains the premier method of spore control, the basis of a huge worldwide industry, and still relying on the basic kinetics of inactivation of Clostridium botulinum spores, and the reasoning regarding safety first evolved by Bigelow et al. in 1920 and Esty and Meyer in 1922. 'Newer' processes such as treatment with ionizing radiation (first proposed in 1905) and high hydrostatic pressure (first proposed in 1899) may be introduced if consumer resistance and some remaining technical barriers could be overcome.