Selection and viability after ingestion of vegetative cells, resting spores and resting cells of the marine diatom, Chaetoceros pseudocurvisetus, by two copepods

Feeding response of two copepods Neocalanus flemingeri and Calanus sinicus on cultures of three life-forms; vegetative cells, resting spores and resting cells, of Chaetoceros pseudocurvisetus was investigated. N. flemingeri fed heavily on the vegetative cells but scarcely responded to feed on the resting spores. C. sinicus showed significantly higher filtering rate on the vegetative cells and resting cells than on the resting spores. Survival of the three life-forms of C. pseudocurvisetus after gut passage of the copepods was also studied. The resting spores could germinate from fecal pellets of both N. flemingeri and C. sinicus; however, both the vegetative cells and the resting cells could not survive ingestion by the copepods. These results suggest that resting spore forming diatoms, such as C. pseudocurvisetus form spores which have a low nutritional value and during gut passage are largely indigestible due to the heavily silicified frustules and thus minimize the effects of grazing by copepods.     

Enhanced adhesion and chemoattraction of zoospores of the fouling alga enteromorpha to some foul‐release silicone elastomers

Significantly higher numbers of zoospores of the fouling, green alga Enteromorpha adhered to silicone elastomers cured by dibutyltin dilaurate (DBTDL) than to identical polymers cured by dibutyltin diacetate (DBTDA). Enhanced zoospore adhesion was shown to be due to the presence of DBTDL and the effect was concentration‐dependent. Further experiments revealed that enhanced zoospore adhesion also occurred to glass coverslips coated with lauric acid (C₁₂) and other saturated fatty acids. The possibility that fatty acids may act as chemical cues (chemoattractants), guiding motile zoospores to the substratum for settlement in the natural environment is discussed. Settlement of other fouling organisms to DBTDL‐cured silicone elastomers is currently being investigated.     

Physico-chemical and hygienic property modifications of stainless steel surfaces induced by conditioning with food and detergent

The effect of repeated conditioning procedures (25 runs), consisting of soiling (milk and meat products) and cleaning steps, on the hygienic status, physico-chemical properties and surface chemical composition of stainless steel (SS) surfaces, was investigated. Five SSs differing in grade and finish were used. Both soiling and surface cleaning/conditioning procedures resulted in a similar increase in the surface contamination with carbon, while the changes in the basic component of the surface free energy depended on the conditioning procedure. The passive film was also affected, the Fe/Cr ratio in particular. The hygienic status was also changed, especially with milk as shown by monitoring the number of residual adhering Bacillus cereus spores after contaminating the surface with spores followed by cleaning. The results show that in food environments, the presence and the nature of conditioning molecules play a major role in the hygienic status of SS surfaces.     

Palynological assessment of Holocene mangrove vegetation at the American Memorial Park,Saipan, Northern Mariana Islands

Pollen and spores recovered from three cores of Holocene to recent deposits from the island of Saipan indicate the presence of mangrove vegetation, including Bruguiera and Acrostichum, on the island previous to World War II. The occurrence of Casuarina equisetifolia Linneaus 1759, from cores elsewhere on the island of Saipan, at depths predating the arrival of humans to the island, suggest that this tree species is endemic to Saipan rather than a recent invasive species. These findings will assist in replanting native vegetation once destroyed through wartime activities on the island.     

Considerations in the grouping of plant and fungal taxa for an epidemiologic study

Although exposure to airborne pollen grains and fungal spores has been implicated as a causative factor for acute exacerbation of asthma, the few epidemiologic studies that have attempted to evaluate the relationship between these bioaerosols and asthma have used only total counts (ignoring the relative importance of different taxa) or a few predominant pollen or spore types (ignoring less abundant but potentially relevant groups). This paper reports the development of hypothesis‐driven exposure metrics (based on known aeroallergen associations with allergic asthma and other hypersensitivity diseases, pollen allergen cross‐reactivity, and the presence of local sources in the city of Fresno, California, USA) for a 3.5 year epidemiologic study of childhood asthma. Outdoor regional and neighborhood concentrations of pollen and spores were measured using Hirst‐type, 7‐day samplers. Indoor and outdoor residential concentrations were measured at 84 selected homes with similar 24‐hour slit impactors. All pollen and spore concentrations were recorded in 2‐hour intervals to assist in understanding diurnal fluctuations in aeroallergen concentrations, identify exposures during the time periods that children are outdoors, and study interaction between aeroallergens and other air contaminants, which were the primary focus of the study. The 124 pollen taxa that were observed were reduced to 15 categories and the 66 fungal and algal taxa were reduced to five categories that will be used in microenvironmental models to generate individual daily exposure estimates for each of the 315 children. These new exposure metrics will allow examination of health effects for taxa traditionally associated with allergy and those with locally elevated concentrations in combination with exposures to other indoor and outdoor air contaminants.     

大叶黑桫椤孢子超低温保存

大叶黑桫椤孢子在液氮中长期保存的结果表明：（1）大叶黑桫椤孢子可以保存于液氮中;（2）液氮保存后的孢子萌发率比未用液氮保存的普遍下降,保存90d的用室温慢速化冻的孢子萌发率最高（65.3％）,相对保持率最高可达79.3％;（3）采用室温（22～25℃）慢速化冻的效果优于37℃温水浴快速化冻的。据此认为,液氮超低温长期保存大叶黑桫椤孢子是可行的。     

When to cut your losses: Dispersal allocation in an asexual filamentous fungus in response to competition

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