Preservation Of Spores Research Articles

Tafonomia de Esporos de Pteridófitas Encontrados em Sedimentos Turfosos Quaternários do Rio de Janeiro, Brasil

Taphonomy is a tool used in palaeoenvironmental interpretations dating back to the process of palynomorphs deposition. The interpretation of taphonomic studies provides subsidies to the understanding of the environmental past conditions through the marks left on the preserved palynomorphs. The study area is located in the Praia Vermelha, Urca district, municipality of Rio de Janeiro, in the entrance of Guanabara Bay. The preservation of spores inside a columnar profile, constituted of peat and sandy mud sediments, was studied, comprising a time interval from about 4,520 to 4,270 years B.P. Eight levels were selected and sampled. The spores were classified according to the type of deterioration, by damages of corrosion and degradation and by mechanical damages. The percentage of each kind of deterioration was calculated in relation to the total number of counted spores and the concentration in relation to one cm³ of sediment. A large number of spores presenting corrosion and degradation damages was observed, being characteristic of air exposure, indicating occasions of lower water availability in this site. The predominance of undamaged spores in some levels suggests an underwater sedimentation, corroborated by sedimentary analyses.

Rapid diagnostic thin section electron microscopy of bacterial endospores

Emerging infectious diseases such as SARS and the bioterror attacks with anthrax spores that occurred after September 11th, 2001 have highlighted the need to be better prepared for the detection and management of infectious pathogens that threaten public health. Negative staining electron microscopy is one method used to screen environmental and clinical samples for relevant infectious pathogens. Unfortunately, bacterial endospores, like those of Bacillus anthracis, are difficult to identify using this method because of their density that prevents imaging of structural details. Thin section electron microscopy would be an alternative method but this usually requires a few days for preparation and diagnosis. In the present paper we describe the development of a rapid thin section protocol, using mainly Bacillus subtilis spores as a model, which allows an unequivocal diagnosis of endospores within 2 h. The protocol involves chemical fixation assisted by heat or microwaves, rapid dehydration, embedding in the low-viscosity resin LR White and chemically enhanced polymerization. Structural preservation of spores is comparable to preservation after standard Epon embedding. Immunolabeling experiments using B. atrophaeus spores and a specific antibody suggest that the protocol preserves significant antigenicity for on-section immunocytochemistry and therefore offers the possibility for the strain typing of spores using specific antibodies. Further experiments with vegetative bacteria, viruses and cell cultures indicate that the rapid thin section protocol not only preserves spores but also other biological structures. Because of its universality and speed the described protocol complements negative staining electron microscopy as a front line method for the morphology-based diagnosis of pathogens in environmental and clinical samples.

Survival of Chlorophyllous and Nonchlorophyllous Fern Spores through Exposure to Liquid Nitrogen

Survival of Chlorophyllous and Nonchlorophyllous Fern Spores through Exposure to Liquid Nitrogen

Cryopreservation of spores of vesicular–arbuscular mycorrhizal fungi*

summaryStorage of spores of vesicular‐arbuscular (VA) mycorrhizal fungi in soil at 5 °C is a common way of preserving these fungi. This method was satisfactory for Glomus intraradix Schenck & Smith but not for Gigaspora margarita Becker & Hall, Glomus mosseae (Nicol. & Gerd.) Gerdemann & Trappe, and Acaulospora longula Spain & Schenck. Preservation of spores at −60 to −70 °C was examined. Cryoprotectants such as DMSO, glycerol, mannitol, and sucrose were ineffective using the freeze‐damage sensitive species G. margarita. Incubation for 47 h in 0.75 to 1.0 M trehalose conferred a measure of freeze damage protection to the spores such that germination rates of previously frozen spores of G. margarita were one tenth to one sixth of controls. The best method of cryoprotection and cryopreservation was found to be slow drying of pot culture soil and freezing the spores in situ. This procedure was satisfactory for the five genera of VA mycorrhizal fungi evaluated.

Preservation of Spores of Vesicular-Arbuscular Endophytes by L-Drying

The spores of four species of vesicular-arbuscular endophytes were L-dried at 22 degrees C, and their viability was tested after heating at 80 degrees C for up to 40 min. L-drying of spores in the soil in which they developed was a very effective method of preservation of all spore types examined. Slow L-drying of spores separated from soil and supported on glass fiber filters also gave high viability for spores of some species. A scheme for the long-term preservation of vesicular-arbuscular endophyte spores is proposed.

Fungus Spores in East African Lake Sediments. V.

(1967). Fungus Spores in East African Lake Sediments. V. Mycologia: Vol. 59, No. 3, pp. 397-404.

Palynology of late Cretaceous mammal beds, Scollard, Alberta (Canada)

Fossil mammal bones have been located in Upper Cretaceous (Lance or Maastrichtian) Upper Edmonton Beds above the Kneehills Tuff in the Scollard area, Alberta (Canada). Samples from the mammal-bearing beds and from above and below, have been analysed for their palynological contents. Abundant microflora representing pteridophytes, gymnosperms and angiosperms have been recorded with an abundance of Aquilapollenites in varied morphological diversity. The microflora showed five paleoecological stages. The lowest Microfloral Assemblage I, representing mid-Middle Edmonton vegetation, indicates swampy, tropical and humid climate which was replaced by stages of a sere of cooler climate shown by Microfloral Assemblage II. Cooling increased still more, possibly due to descrease in the total solar radiation reaching the earth's surface, caused by the volcanic dust in the atmosphere as the bentonitic content is high. Microfloral Assemblage III from the bentonitic beds associated with the Kneehills Tuff shows little preservation of spores and pollen although comminuted fragments are present. Microfloral Assemblage IV (including the mammal beds) shows warming up and restoration of vegetation but of a cooler climate. Climate became warmer during the deposition of Microfloral Assemblage V and a rich woodland vegetation was established representing warm subtropical climate with warm temperate aspect during mid-Upper Edmonton deposition.