Critical aspects of fluorescent age-pigment methodologies: Modification for accurate analysis and age assessments in aquatic organisms

Fluorescent age-pigment (FAP) quantification has recently been proposed as a means of estimating age in aquatic vertebrates and invertebrates. However, various aspects related to currently adopted procedures remain untested and a distinct relationship between FAP accumulation and chronological age has yet to be established. The present study was undertaken to critically evaluate the effects of specimen and extract handling procedures (including temperature, time, ultrasonication, and solvent systems) on the expression of native FAP fluorescence using the post-mitotic tissues of laboratoryreared specimens of the teleostOreochromis mossambicus as model systems. FAP-like fluorophores increased in vitro in brain, heart, and muscle tissues and their extracts with increased storage temperature (–20°C and above) and time. Sonification of homogenates greatly enhanced this effect and generated other non-native fluorophores in sample solution. Fluorescence assay temperature also affected expression of results, and aqueous-phase extracts, used in previous studies, were found to contain large amounts of fluorescent flavin contaminants. Using modifications of the above procedures, age-related patterns of accumulation were subsequently examined inO. mossambicus brain and, for the first time, positive correlations between chronological age and whole organ as well as weight-specific FAP concentration were validated. The significance of these findings are discussed in relation to previous FAP studies.     

Activity,track and speed of movement of the crab Scylla serrata in an estuary

Ultrasonic transmitters were used to track the movements of the crab Scylla serrata (Forskal) over 24 h periods in the Kowie estuary, South Africa. Laboratory experiments using infra-red time-lapse photography to record activity indicated that the transmitters did not affect duration of emergence, amount of movement or feeding. In the estuary, S. serrata was active on average for 13 h. out of 24 h, most activity was at night. The distance moved per night by continuously tracked crabs averaged 461 m, but ranged between 219 and 910 m. Most movement was slow, modal speed was 10 to 19 m h^-1. Slow movements were independent of direction of current and are assumed to be related to use of contact chemoreception for location of prey. About one-seventh of movements were faster than 70 m h^-1; these were most frequently against the current and may be related to olfactory location of food. The crabs did not occupy a distinct territory, but tended to remain in the same general area although they were capable of moving at least 800 m along the length of the estuary at night.     

The effect of rearing environment on blue structural coloration of eastern bluebirds (<Emphasis Type="Italic">Sialia sialis</Emphasis>)

We used a brood-size manipulation to test the effect of rearing environment on structural coloration of feathers grown by eastern bluebird (Sialia sialis) nestlings. Ultraviolet (UV)-blue structural coloration has been shown to be sexually selected in this species. Our experimental design took advantage of the growth of UV-blue wing feathers in nestlings that are retained as part of the first nuptial plumage. We cross-fostered nestlings to create enlarged and reduced broods with the purpose of manipulating parental feeding rates and measured the effect on nestling growth and plumage coloration. Brood size influenced feeding rates to offspring, but the effect varied with season. In general, male nestlings reared in reduced broods were fed more often, weighed more, and displayed brighter structural plumage compared to nestlings reared in enlarged broods. Female nestlings appeared to experience less adverse affects of brood enlargement, and we did not detect an effect of brood-size manipulation on the plumage coloration of female nestlings. Measures of plumage coloration in both males and females, however, were correlated to hatching date and nestling mass during feather development. These data provide empirical evidence that environmental quality can influence the development of the blue structural coloration of feathers and that males may be more sensitive to environmental fluctuations than females.     

Denitrification: its importance in a river draining an intensively cropped watershed

Nitrogen transport was studied during summer low flows in a 20-km reach of the Nottawasaga River which drains an intensively cropped sand plain which has an underlying shallow water-table aquifer. Nitrogen inputs to the river were measured on days in May to October of 1977-81. These data indicated that about 38% of the daily nitrate input entered the river through ground water. The magnitude of this input is a consequence of widespread contamination of the shallow aquifer by nitrogen fertilizer. Ground water entering the river from springs and seeps near fertilized fields frequently contained more than 10 mg 1^?1 of NO₃-N. Mass balance studies of nitrogen transport in the river revealed an average daily nitraof 46 ± 23 kg N. This rate of nitrate removal represented about 40% of the ground water input to the river from the sand plain. Analysis of a mass balance for total Kjeldahl nitrogen revealed an essentially balanced budget, whereas chloride showed a small daily gain of about 5%. Laboratory experiments involving the incubation of stream sediment cores and the use of the acetylene block technique suggested that the bulk of the nitrate loss during river transport was caused by denitrification in bottom sediments.     

Aggregation of Adenovirus 2 in Source Water and Impacts on Disinfection by Chlorine

It is generally accepted that viral particles in source water are likely to be found as aggregates attached to other particles. For this reason, it is important to investigate the disinfection efficacy of chlorine on aggregated viruses. A method to produce adenovirus particle aggregation was developed for this study. Negative stain electron microscopy was used to measure aggregation before and after addition of virus particles to surface water at different pH and specific conductance levels. The impact of aggregation on the efficacy of chlorine disinfection was also examined. Disinfection experiments with human adenovirus 2 (HAdV2) in source water were conducted using 0.2 mg/L free chlorine at 5 °C. Aggregation of HAdV2 in source water (≥3 aggregated particles) remained higher at higher specific conductance and pH levels. However, aggregation was highly variable, with the percentage of particles present in aggregates ranging from 43 to 71 %. Upon addition into source water, the aggregation percentage dropped dramatically. On average, chlorination CT values (chlorine concentration in mg/L × time in min) for 3-log₁₀ inactivation of aggregated HAdV2 were up to three times higher than those for dispersed HAdV2, indicating that aggregation reduced the disinfection rate. This information can be used by water utilities and regulators to guide decision making regarding disinfection of viruses in water.     

Vegetation: A Sink for Atmospheric Pollutants

The possibility of vegetation being an important sink for gaseous air pollutants was investigated. Plant pollutant uptake measurements were made utilizing a typical vegetation canopy and chambers that were designed specifically for gaseous exchange studies. The data indicate that an alfalfa canopy removed gases from the atmosphere in the following order: hydrogen fluoride (HF) > sulfur dioxide (SO₂) > chlorine (Cl₂) > nitrogen dioxide (NO₂) > ozone (O₃) > peroxyacetyl nitrate (PAN) > nitric oxide (NO) > carbon monoxide (CO). The absorption rate of NO was low, and no absorption of CO could be detected with the methods used. In the typical ambient concentration range uptake increased linearly with increasing concentration except for O₃ and Cl₂ which caused partial stomatal closure at the higher concentrations. Wind velocity above the plants, height of the canopy, and light intensity were shown to affect the pollutant removal rate. A relationship between the absorption rate and solubility of the pollutant in water was also shown. It was concluded that vegetation may be an important sink for many gaseous air pollutants.     

Land Use for Military Training in the UK: The Current Situation,Likely Developments and Possible Alternatives

This paper describes the current pattern of land ownership for military training in the UK. The main component-armytraining areas-is considered in detail. Recent historical trends are reviewed in the context of changes in force size and weapons systems.Problems and benefits arising from the primary use of land for military training are defined. Relevant literature is reviewed. Comparisons are made with training systems in other countries, in particular the USA, the Netherlands,Switzerland, France and Australia. Recent developments in government policy are described and analysed. Possible future requirements are explored. This information is used to construct an argument that the current training system in the UK is outmoded and unsustainable. The authors contend that there is a need for a strategic review of military training, encompassing a thorough assessment of alternatives to traditional live firing on dedicated training areas.