Polen y esporas de la Formación La Irene (Maastrichtiano), sudoeste de la provincia de Santa Cruz, Argentina: primeros resultados

Palynological assemblages are reported for the first time for the La Irene Formation, southwestern Santa Cruz Province, Argentina. This unit represents the sedimentation during a regressive period from transitional or delta-plain to fluvial environments. Palynological assemblages are scarce and moderately well preserved. They mainly consist of continental elements (wood remains, cuticles, spores and pollen grains) with scarse marine palynomorphs (dinoflagellate cysts). The spore-pollen assemblages are dominated by fern spores, followed by angiosperm and gymnosperm pollen grains. Bryophyte spores and fungal remains are also present. Among ferns, Cyatheaceae and spores of Laevigatosporites, of uncertain affinity, are dominant. Of the angiosperm pollen, those of Chloranthaceae (Clavatipollenites sp.) and Arecaceae (Arecipites spp., Longapertites sp., Spinizonocolpites hialinus Archangelsky and Zamaloa) are the most abundant. Pollen of Liliaceae (Liliacidites spp.), Proteaceae (Proteacidites sp., Peninsulapollis gillii (Cookson) Dettmann and Jarzen, Retidiporites camachoii Archangelsky) and Ericaceae (Ericipites scabratus Harris) are also present. Gymnosperm pollen is represented by Podocarpaceae (Podocarpidites spp.) and Ephedraceae (Equisetosporites sp.). These palynological suites would represent a fern-angiosperm dominated coastal vegetation, developed under warm and at least locally humid climatic conditions. La Irene Formation is considered Maastrichtian in age based on stratigraphic evidence, which is, in turn consistent with the ages suggested by the species ranges and the similarities observed with others previously described assemblages. This is the southernmost record of Spinizonocolpites, similar to the extant mangrove palm Nypa.     

Interet de la microscopie electronique a balayage pour l'etude morphologique des spores de levures

The morphology of spores is an important aspect of yeasts systematic. It is a good thing to state the size, the shape and the ornamentation of these spores; only scanning electron microscopy is able to bring a satisfactory answer. This preliminary work applied toEndomycopsis javanensis (Klöcker)Dekker spores shows that their warty aspect is due to the presence of warts and mamelons and that the width of the equatorial edge varies considerably for a given spore and from one spore to another.

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Laboratoire de Botanique Appliquée I.B.A.N.A. — Faculté des Sciences — Dijon.

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avec la collaboration technique deM. Bert, responsable de la microscopie électronique à balayage à la Faculté des Sciences de Dijon.     

Le bassin permien de Guardia Pisano (Sud-Ouest de la Sardaigne, Italie) : palynostratigraphie, paléophytogéographie, corrélations et âge radiométrique des produits volcaniques associés

The Permian section outcropping at Guardia Pisano (Sulcis area, SW Sardinia), comprises two successions, separated by an unconformity. The lower succession is composed of grey-black sandy shales, rich in plant remains and in sporomorphs, deposited in a fluvial-lacustrine to palustrine environment; followed by layers of rhyolithic lavas and volcanoclastites with silicified plant trunks. Most of the analysed samples yielded a profusion of pollen and spores in a very good state of preservation. Three associations were distinguished. The first one comprises mostly radial and bilateral monosaccate pollen grains and very few spores. This association is characterized by the presence of pollen grains of the genera Crucisaccites, Luberisaccites, Gondwanopollis and Lueckisporites, together with very abundant Potonieisporites and subordinate Florinites. The second association comprises mostly pollen grains of the genus Potonieisporites, represented by many species, together with Limitisporites, Costapollenites, Vittatina and others. Spores mainly represented by azonate trilete and monolete types are more frequent than in the previous association. These first two palynological associations reflect assemblages of meso-xerophilous plants growing in dryer environments, belonging to tropical and subtropical phytogeographic biomas. The third association, mainly composed of Sphenophyte spores, is autochthonous and corresponds to a swampy hygrophilous flora settled after the filling up of the basin. The age inferred by means of sporomorphs is early Asselian which is in good agreement with the mean radiometric age of the volcanic rocks obtained by the ‘SHRIMP’ and the lead-zircon evaporation methods (297 ± 5 Ma). The upper succession, is composed of grey to red sandstones and thin pelites deposited on an alluvial plain under very hot and humid climate; its Permian, post-Asselian age cannot be better constrained because of the scarcity of the fossil content.     

Effets d'un Sejour à l'Obscurité sur le Pouvoir Germinatif et sur L'Evolution de l'Appareil Photosynthétique des Spores de Funaria hygrometrica

In Funaria spores fine structural changes occur, especially in the plastids, during prolonged incubation in darkness on an inorganic liquid medium, although under these conditions germination cannot take place. If then exposed to illumination, these spores germinate rapidly and synchronously. Chloroplasts formed in darkness have thicker grana, absorb more CO₂, have a higher reducing power, and give a more intense paramagnetic resonance signal than chloroplasts formed in light.     

Late Carboniferous miospores from the Tarma Formation,Pongo de Mainique,Peru

For the first time, a palynologic assemblage is described from the upper section of the Tarma Formation, Peru. It is dominated by monosaccate pollen grains with subordinate striate grains and very few spores. The abundance of Illinites unicus has allowed a revision of the systematic position of the form-genus Illinites. The assemblage is correlated with the Illinites unicus palynozone from the Amazonas Basin, and is considered to be of Westphalian C/Late Atokan age.     

Sur la presence d'un riche microplancton siluro-devonien a Acritarches,spores et Chitinozoaires au sommet des schistes et quartzites de Plougastel (Rade de Brest-Finistere); son interet stratigraphique

The upper part of the “Schistes et quartzites de Plougastel” Formation reveals a rich assemblage of microplancton (spores, Acritarchs and Chitinozoans) of lower Lochkovian age. Preliminary studies show that this Formation was beginning within the silurian.     

Investigations on the occurrence of bacteriophage-free spores ofBacillus Megatherium 899 of den Dooren de Jong

Summary It has been tried to isolate fromB. megatherium strain 899 fromden Dooren de Jong a spore that does not contain phage. This has failed. Moreover it has been proved, that in case a suspension containing spores is heated to 80°C., not all the spores are resistent to this temperature as one would expect, but only about 1%. It is left open, whether phage-free spores may occur.     

Etude Ultrastructurale de la Sporulation de Paramarteilia orchestiae gen. n., sp. n., Parasite de l'Amphipode Orchestia gammarellus (Pallas)

RESUME. L'individualisation de 2 spores bicellulaires à partir d'un měme pansporoblaste caractérise la sporulation du parasite de l'Amphipode Orchestia gammarellus (Pallas) précédemment décrit sous le nom de Marteilia sp. Cette sporulation le distingue des espèces du měme genre parasite d'Hutres qui sont toutes caractérisées par la production de spores tricellulaires. Les conditions semblables dans lesquelles les pansporoblastes paraissent se differencier à partir d'une cellule souche dans laquelle ils poursuivent leur évolution vers la sporogenèse ainsi que divers caractères cytologiques communs, nous incitent à maintenir tous ces parasites dans une měme famille mais à placer celui de l'Amphipode dans un genre différent. Nous proposons de le nommer Paramarteilia orchestiae gen. n., sp. n.
Ces parasites ne peuvent ětre maintenus dans les Protozoaires en raison de leur évolution vers la pluricellularité et de l'individualisation de ces éléments somatiques que représentent la cellule souche primaire, les pansporoblastes et cellules sporales (à l'exception des sporoplasmes). Il semble logique de les inclure dans l'embranchement des Myxozoaires créé par Grassé pour les Myxosporidies et Actinomyxidies qui différencient également des spores pluricellulaires et des éléments somatiques. Les centrioles à 9 singlets de P. orchestiae ainsi que les cellules primaires uninucléées, quel que soit le nombre de pansporoblastes qu'elles contiennent, peuvent ětre considérés comme des caractères résiduels d'Unicellulaires.     

Sur les plantes vasculaires dans le devonien de Libye

Study of the vegetation in Libya during the Devonian period has been made in different works concerning macrofossils (psilophytes, rhyniophytes, trimerophytes and lycophytes of the Murzuk Basin) and microrests and spores of the Rhadamès Basin.A comparison between the spores found in the sediments and those of fossil plants already known in other areas of the world, during the Devonian allowed us to confirm the hypothesis suggested by the study of microrests. Thus, one may suppose that during the Devonian period in Libya, as well as the four groups mentioned above, there may also have lived some plants such as sphenophytes (?) (one spore genus), filicophytes (?) (stomates and spores of five species), progymnosperms (?) (tracheids and spores of two species) and paleophyllales (?) (spore of one species).     

Moist-heat resistance, spore aging, and superdormancy in Clostridium difficile

Clostridium difficile spores can survive extended heating at 71°C (160°F), a minimum temperature commonly recommended for adequate cooking of meats. To determine the extent to which higher temperatures would be more effective at killing C. difficile, we quantified (D values) the effect of moist heat at 85°C (145°F, for 0 to 30 min) on C. difficile spores and compared it to the effects at 71 and 63°C. Fresh (1-week-old) and aged (≥20-week-old) C. difficile spores from food and food animals were tested in multiple experiments. Heating at 85°C markedly reduced spore recovery in all experiments (5 to 6 log(10) within 15 min of heating; P < 0.001), regardless of spore age. In ground beef, the inhibitory effect of 85°C was also reproducible (P < 0.001), but heating at 96°C reduced 6 log(10) within 1 to 2 min. Mechanistically, optical density and enumeration experiments indicated that 85°C inhibits cell division but not germination, but the inhibitory effect was reversible in some spores. Heating at 63°C reduced counts for fresh spores (1 log(10), 30 min; P < 0.04) but increased counts of 20-week-old spores by 30% (15 min; P < 0.02), indicating that sublethal heat treatment reactivates superdormant spores. Superdormancy is an increasingly recognized characteristic in Bacillus spp., and it is likely to occur in C. difficile as spores age. The potential for reactivation of (super)dormant spores with sublethal temperatures may be a food safety concern, but it also has potential diagnostic value. Ensuring that food is heated to >85°C would be a simple and important intervention to reduce the risk of inadvertent ingestion of C. difficile spores.     

A note on the effect of sporulation conditions on the resistance of Bacillus spores to heat and chemicals

Spores of Bacillus subtilis SA22 harvested after 22 d incubation on nutrient agar at 30°C were more resistant to 0–04% peracetic acid at 20°C than spores harvested following 2 d incubation. Similarly, spores of B. subtilis globigii B17, harvested after 7 d incubation on a sporulation agar were up to 10 times less resistant to 0.04% peracetic acid at 20°C than spores harvested after 35 d incubation. An increase in resistance to heating at 100°C and to exposure to 17.7% hydrogen peroxide at 20°C occurred as the age of B. subtilis SA22 spores prior to harvesting increased, whereas differences in resistance were not observed with spores of B. subtilis globigii B17.     

The Effect of Sporulation Temperature on the Resistance of Bacillus subtilis to a Chemical Inhibitor

The ability of spores of Bacillus subtilis to germinate at 50° in sublethal concentrations of chlorocresol is related to sporulation temperature as is the resistance of the subsequent outgrowth at 50° to this substance. The degree of germination, age of spores and amount of outgrowth produced are of minor importance in determining resistance of the outgrowth.     

Spore age and coverslip placement affects germination and post-germination development of Colletotrichum dematium var circinans

Spore suspensions from young (10–14 da; young spores) and old (4 mo; old spores) colonies of PColletotrichum dematium var circinans were placed on slides. Coverslips were left off, placed on in the normal manner, or supported on shims. Slides were placed in moist chambers and incubated in light or dark for up to 48 hrs. Germination and post-germination development were studied. Shimming had some beneficial effect on germination, especially for old spores in dark. In general, more germ-tubes and appressoria were produced on spores under shims than spores with other coverslip treatments. By 48 hrs more old spores under shims germinated, and greater numbers of germ-tubes and appressoria were produced than on other old spores under different coverslip treatments. However, numbers produced were lower than those predicted for comparably treated young spores. Spore age, incubation regime, and placement of coverslips did not affect germ-tube initiation. For all treatments more germ-tubes were initiated from spore tops than bottoms or tips. Fewer germ-tubes were initiated from spore centers than other locations on tops and bottoms, and from both tips than one tip. Approximately 26 % of all appressoria were produced sessile. A higher percentage of sessile appressoria were produced on old spores (80 %) than on young spores (20%).     

Failure to decontaminate Glomus clarum NT4 spores is due to spore wall-associated bacteria

 Exposure of spores of Glomus clarum NT4 to solutions of chloramine-T (2.5–10% w/v) for 10–120 min failed to fully decontaminate all spores. Scanning electron microscopy did not show the presence of contaminants on treated spores, but transmission electron microscopy revealed bacterial cells embedded within the outer spore wall layer. Bacteria that remained protected within the spore walls were detected only when the spores were placed on appropriate media. Nutrient agar and tryptic soy agar supported relatively high levels of contaminant growth and were regarded as good media for assessing contamination, whereas the detection of contaminant growth on water agar required prolonged incubation. Contamination and germination of G. clarum NT4 spores following decontamination treatments were dependent on spore age. Generally, lower concentrations of chloramine-T and shorter incubation periods were required to reduce contamination of freshly harvested spores than of mature spores. Exposure to 10% chloramine-T for 120 min was required to reduce the levels of contamination of mature spores to ≤10%. Unfortunately, spore germination was compromised by rigorous decontamination treatments, thus the success of any decontamination procedure should be evaluated prior to its routine use. Moreover, if the interpretation of experimental results rests on the assumption of true surface sterility of VAMF spores, we suggest that the axenic condition of spores be confirmed prior to experimentation on a medium that encourages contaminant growth. Accepted: 12 July 1995     

QUALITATIVE AND QUANTITATIVE STUDIES OF THE SWIMMING BEHAVIOR OF HINCKSIA IRREGULARIS SPORES (PHAEOPHYCEAE)

The swimming behavior of spores of the brown alga Hincksia irregularis was analyzed using computer-assisted motion analysis. We distinguished five main swimming patterns: straight paths, search circles, orientation, gyration, and wobbling. We suggest different functional values for the individual swimming patterns. Straight paths, search circles, and orientation are different but all may be important in small-scale movements in the benthic boundary layer. As such, they could enable a spore to find a suitable microenvironment for germination and growth. Gyration occurs during the initial reversible phase of adhesion that can lead to settlement. Wobbling is typical for irritated or mechanically damaged spores and does not seem to be a typical pattern associated to settlement. The dominant swimming patterns changed with spore age (10 ± 5 to 60 ± 5 min of spore age), with young spores mainly swimming in straight paths and search circles and older spores in orientation and gyration. This change in swimming patterns can be quantified by speed (decrease over time) and rate of change of direction (increase over time). Based on these results, we suggest that computer-assisted motion analysis of the swimming behavior of H. irregularis spores can be used to develop bioassays with both ecological and technological relevance.     

Germination of Bacillus megaterium spores after various extraction procedures

The initiation of germination of Bacillus megaterium QM B1551 spores, grown in supplemented nutrient broth, has been studied. The initiation properties depend on buffer concentrations and the particular batch of spores. Initiation in l-alanine, KBr, calcium dipicolinate, or in buffer alone increases as a function of the spore age; whereas initiation in glucose, l-leucine, or l-proline remains relatively constant. Extraction of spores with alkali, sodium dodecyl sulfate-dithiothreitol, or lithium diiodosalicylate removes variable amounts of dipicolinic acid, hexosamine, and protein. These extracted spores are still capable of initiation and, in some cases, initiation is stimulated. However, extraction of spores with 8 M urea-10% mercaptoethanol inhibits subsequent initiation.     

Studies of aureobasidium pullulans (de Bary) Arnaud

Summary The dark pigmentation ofAureobasidium pullulans is due to melanin that stains the walls and may be heavily encrusted on the surface of older cells. The pigment granules can be shaken off ultrasonically. The melanin is quite impervious to ultraviolet light.Most strains ofA. pullulans observed secrete a viscous mucin that encloses hyphae and spores in a matrix. In both hyphae and yeastlike blastospores, cross walls develop centripetally, and in many cases a pore is left in the cross wall, rendering possible protoplasmic movement and a heterokaryotic condition, which may account for the variability of the species. These wall pores are not like those found in Basidiomycetes.The blastospores contain droplets of lipid, and usually have but one nucleus though the few larger spores may have two or rarely three nuclei. The blastospores are not borne on stipules but bud from the parent cell in a manner similar to yeasts and leave behind a bud scar.     

Procedures for the characterisation of bioaerosol particles. Part II: Effects of environment on culturability

The behaviour of bioaerosol particles in industrial and health-careapplications may be most effectively understood once they have beenquantitatively assessed using well-characterised sampling and assaytechniques. However, the large number of different conditions possiblein this wide range of applications makes the assessment of bioaerosolparticles very difficult. In addition to the effects of differentsampling and assay technologies, the mechanism of aerosolisation andenvironmental conditions can influence bioaerosol behaviour. The effectsof sampler selection and suspension aerosolisation on bioaerosolviability were reported earlier as ``Part I' of two papers, and theeffects of the environment on the culturability of three different typesof microorganism are reported here as ``Part II'. The environmentalrelative factors considered in the present study are: relativehumidity (RH), aerosol-age, and a number of gaseous pollutants. A smallnumber of additional tests, examining the effects of aerosolisationmethod on culturability, are also reported. A combination of anenvironmentally controlled Bioaerosol Test Chamber and Goldberg RotatingDrum were shown to be an appropriate facility to carry out the study.Changing RH was shown to have a considerable effect on the culturablefraction of aerosolised Sacharomyces cerevisiae cells but notPenicillium expansum spores or Bacillus subtilis var.niger spores. In this text, ``culturable fraction' is definedas the fraction of the total number of microorganisms in a sample thatwill form colonies (i.e. grow and reproduce) on a suitably preparedculture plate under optimum conditions for the species of microorganismunder consideration. After the initial shock of aerosolisation, theculturable fraction of S. cerevisiae cells and P.expansum spores is not further affected by increasing aerosol age.Results from an earlier study have shown spray suspension and collectedaerosol age also have no effect on culturability of P. expansumspores. The effects of gaseous pollutants are reflected in the reductionin culturability of P. expansum spores following exposure tosulphur dioxide, ozone and ozone hydrocarbon cocktail. This reductionwas never to less than 30% of the unpolluted control. All thetests show that P. expansum spores are fairly robust andbiologically stable. Examination of the effects of aerosolisationtechnique on the culturability of S. cerevisiae shows theCollison nebuliser produces aerosols with the highest culturabilitycompared with either a plain glass atomiser or a Unimed nebuliser usedin these tests.     

Indigenous Arbuscular Mycorrhizal Fungi Associated with Acacia albida Del. in Different Areas of Senegal

The influences of seasons, plant age, and physicochemical properties of the soil on surface and deep biological arbuscular mycorrhizal fungus parameters associated with Acacia albida were assessed in different areas of Senegal. More indigenous arbuscular mycorrhizal propagules were found in the localities of the Sudano-Guinean zone (Djinaki and Kabrousse) than in those of the Sahelian zone (Louga and Diokoul), and species belonging to the genera Glomus, Gigaspora, Acaulospora, and Sclerocystis prevailed. The numbers of total and viable spores increased more during the rainy season than during the dry season (about 108% more total spores and 262% more viable spores). Similarly, both total and viable spores were more prevalent around young Acacia trees than old trees. However, the intensities of root colonization did not differ in each ecoclimatic zone.     

Bacillus subtilis builds structurally and functionally different spores in response to the temperature of growth

Bacterial spores are commonly isolated from a variety of different environments, including extreme habitats. Although it is well established that such ubiquitous distribution reflects the spore resistance properties, it is not clear whether the growing conditions affect the spore structure and function. We used Bacillus subtilis spores of similar age but produced at 25, 37, or 42°C to compare their surface structures and functional properties. Spores produced at the 25°C were more hydrophobic while those produced at 42°C contained more dipicolinic acid, and were more resistant to heat or lysozyme treatments. Electron microscopy analysis showed that while 25°C spores had a coat with a compact outer coat, not tightly attached to the inner coat, 42°C spores had a granular, not compact outer coat, reminiscent of the coat produced at 37°C by mutant spores lacking the protein CotG. Indeed, CotH and a series of CotH-dependent coat proteins including CotG were more abundantly extracted from the coat of 25 or 37°C than 42°C spores. Our data indicated that CotH is a heat-labile protein with a major regulatory role on coat formation when sporulation occurs at low temperatures, suggesting that B. subtilis builds structurally and functionally different spores in response to the external conditions.