Effects of symbiont elimination and reinfection on the life processes of the planktonic foraminifer Globigerinoides sacculifer

Laboratory experiments were carried out to determine the influence of symbiotic dinoflagellates (zooxanthellae) on the shell growth, longevity, and reproductive potential of Globigerinoides sacculifer (Brady). Its symbionts were eliminated by 72-h treatment with a photosynthetic inhibitor (DCMU). Symbiont elimination resulted in earlier gametogenesis (shortened survival time) and smaller shell sizes of G. sacculifer when compared to untreated foraminifera grown in sea water. Individuals kept in continuous darkness in untreated sea water also exhibited early gametogenesis, short survival times and small shell sizes. Aposymbiotic foraminifera formed on the average one or two chambers fewer per individual and their rate of shell size increase is slower than symbiont-bearing foraminifera. Symbionts were lysed within perialgal vacuoles of G. sacculifer when subjected to DCMU treatment or kept in continuous darkness. One DCMU-treated group was reinfected with symbionts from crushed G. sacculifer donors. Soon after reinfection, these foraminifera resumed a shell growth rate and exhibited developmental stages that were nearly equivalent to those of untreated individuals, as deduced from their shell size, frequency of sac-like chambers, rate of gametogenesis, and survival time. Our experiments indicate that the symbionts aid in calcification and that elimination of symbionts triggers gametogenesis, thus shortening the life span of the foraminiferal host. The results imply that shell growth in symbiont-bearing planktonic foraminifera occurs mainly in the euphotic zone and that they do not survive for long periods below it.     

Relative size of Aristotle's lantern in Echinometra mathaei occuring at different densities

Like species of sea urchins in Zanzibar and Oregon (USA), Echinometra mathaei (de Blainville) at Rottnest Island, Western Australia, displays variation in the size of Aristotle's lantern relative to the maximum diameter of the test. This variation was associated with local variations in density of urchins at each of two sites in each of two years (1980 and 1981); this association with density was consistent with the proposal that relatively larger lanterns are a response to decreased food availability. Furthermore, variation of relative lantern size associated with local density was similar in magnitude to the variation displayed between sites and between years. This temporal variation demonstrated the plasticity of the relative lantern size over periods as short as 12 mo. Further experimental studies are required before relative length of lanterns can be used as estimates of food availability.     

Transmission of food preferences in spiny mice (Acomys cahirinus) via nose-mouth interaction between mothers and weanlings

Summary Two laboratory experiments assessed the role of nose-to-head and nose-mouth investigation in the transmission of food preferences from Acomys cahirinus mothers to their offspring. Pups spent more time nosing and licking the nose-mouth area of mothers who ate a novel food (fresh potato or carrot) than of mothers who ate no novel food. A greater amount of the less-preferred novel food (potato) was subsequently eaten by pups whose mothers had eaten potato than pups whose mothers had eaten either carrot or familiar laboratory chow only. Mothers maintained a stereotypic posture during nose-mouth investigation, holding still with mouth slightly open, providing both a source of specific food cues and a context in which pups could become familiar with them. These data suggest an active role by Acomys mothers in the development of offspring food preferences.     

Pt/Mg-Ce-O catalyst for NO/H<Subscript>2</Subscript>/O<Subscript>2</Subscript> lean de-No<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> reaction

The NO/H₂/O₂ reaction was studied under oxidizing conditions in the 100-400 °C range over 0.1 wt% Pt supported on various metal oxides such as MgO, CeO₂, SiO₂, La₂O₃, CaO, Y₂O₃ and TiO₂. The Pt/MgO and Pt/CeO₂ catalysts showed good catalytic behaviours. Here, we find that the Pt/Mg-Ce-O catalyst, prepared from MgO and CeO₂ by the sol-gel method, is a very active and selective catalyst towards N₂ formation in the whole 100–400 °C range. This catalyst appears to be the most active, selective and stable one ever reported in the literature for the NO/H₂/O₂ reaction, even in the presence of 5%v H₂O or 20 ppmv of SO₂ in the feed stream.Selected article from the Regional Symposium on Chemistry and Environment, Krusevac, Serbia, June 2003, organised by Dr. Branimir Jovancicevic.     

Influence of seedling roots, environmental factors and soil characteristics on soil CO2 efflux rates in a 2-year-old loblolly pine (Pinus taeda L.) plantation in the Virginia Piedmont

To understand the role of managed forests in carbon sequestration an understanding of factors controlling soil CO2 efflux will be necessary. This study examined the influence of seedling roots, environmental factors, nutrient availability, and soil characteristics on soil CO2 efflux patterns in a 2-year-old pine plantation in the Virginia Piedmont. Efflux rates were measured both near the base of seedlings and midway between rows in plots that had received fertilization and mulch treatments in a factorial combination. Soil CO2 efflux rates were consistently higher near the base of seedlings, fertilization increased seedling growth with no significant effect on rates. and mulching increased winter efflux rates. In a regression analysis of seasonal soil CO2 efflux, soil temperature explained 42.2% of the variance followed by the interaction of soil temperature and moisture and of soil temperature and plot position, which together explained an additional 9.8% of the observed variance in seasonal rates. During March 2000 measurements, the spatial pattern of soil CO2 efflux between plots was most influenced by differences in soil nitrogen and pine root biomass. Furthermore, spatial differences observed in mean annual efflux rates were found to be highly influenced by the amount of soil coarse fragments in the upper soil profile.     

Topsoil (0-5 cm) composition in eight arctic catchments in northern Europe (Finland, Norway and Russia)

Frozen topsoil samples (0-5 cm) were collected during March/April 1994 in eight Arctic catchments in northern Europe (four in Russia, three in Finland, one in Norway), at different distances and in different wind directions from the emissions of the Russian mining, roasting and smelting industry on the Kola Peninsula. Between 14 and 25 sites were sampled in each of the eight catchments ranging in size from 12 to 35 km2. Results show that close to the smelters in Monchegorsk and Nikel, topsoil is clearly enriched in Ag, As, Bi, Cd, Co, Cr, Cu, Fe, Ni, Pb, Sb, Se, Te and V. Cu and Ni median contents in topsoils collected close to Monchegorsk are about 600 times higher than in the Finnish catchments. The effect of open-cast mining and waste dumps of alkaline rocks from the nephelinite industry near Kirovsk can be seen in the elevated contents of Al, Ba, K, La, Mn, Na, Sr, Ti, Y and Zn in topsoil collected in a nearby catchment. For many elements, however, variations observed in single catchments are as great as the total regional variation. Several elements (e.g. Cd, Hg, Cu, Ni, Pb, S, Zn) show strong positive correlation between the organic content of the sample and the element content observed. Thus it is necessary to determine the organic content of the samples and correct the element levels when using depth-related soil samples (here, the 0-5 cm topsoil layer) for regional mapping.     

Deriving freshwater quality criteria for copper,cadmium, aluminum and manganese for protection of aquatic life in Malaysia

Freshwater quality criteria for copper (Cu), cadmium (Cd), aluminum (Al), and manganese (Mn) were developed with particular reference to aquatic biota in Malaysia, and based on USEPA’s guidelines. Acute toxicity tests were performed on eight different freshwater domestic species in Malaysia, which were Macrobrachium lanchesteri (prawn), two fish – Poecilia reticulata and Rasbora sumatrana, Melanoides tuberculata (snail), Stenocypris major (ostracod), Chironomus javanus (midge larvae), Nais elinguis (annelid), and Duttaphrynus melanostictus (tadpole), to determine 96-h LC50 values for Cu, Cd, Al, and Mn. The final acute values (FAVs) for Cu, Cd, Al, and Mn were 2.5, 3.0, 977.8, and 78.3 μg L^?1, respectively. Using an estimated acute-to-chronic ratio (ACR) of 8.3, the value for final chronic value (FCV) was derived. Based on FAV and FCV, a Criterion Maximum Concentration (CMC) and a criterion Continuous Concentration (CCC) for Cu, Cd, Al, and Mn of 1.3, 1.5, 488.9, and 39.1 μg L^?1 and 0.3, 0.36, 117.8, and 9.4 μg L^?1, respectively, were derived. The results of this study provide useful data for deriving national or local water quality criteria for Cu, Cd, Al, and Mn based on aquatic biota in Malaysia. Based on LC50 values, this study indicated that R. sumatrana, M. lanchesteri, C. javanus, and N. elinguis were the most sensitive to Cu, Cd, Al, and Mn, respectively.     

Injuries as a Result of California Earthquakes in the Past Decade

The devastating effects of earthquakes have been demonstrated repeatedly in the past decade, through moderate and major earthquakes such as the October 1987 Whittier Narrows earthquake (5.9 on the Richter scale), the October 1989 Loma Prieta earthquake (7.1) and the January 1994 Northridge earthquake (6.7). While 'official' tallies of injuries and deaths are reported for each event, the numbers vary from report to report. For Northridge, the number of injuries vary between 8,000 and 12,000; the number of deaths from 33 to 73 (Peek-Asa et al., 1997; Durkin, 1996).While official estimates are commonly reported following disasters, the study of actual numbers, types and causes of casualties has not developed. In this paper, we identify the numbers and risk factors for injuries within community-based samples across three earthquakes in urban California. We first report the numbers and types of injuries in each earthquake and then identify risk factors specifically associated with the Northridge earthquake     

Lorenz Curve and Gini Coefficient: Novel tools for analysing seasonal variation of environmental radon gas

Using a methodology derived from Economics, the Lorenz Curve and Gini Coefficient are introduced as tools for investigating and quantifying seasonal variability in environmental radon gas concentration. While the Lorenz Curve presents a graphical view of the cumulative exposure during the course of the time-frame of interest, typically one year, the Gini Coefficient distils this data still further, to provide a single-parameter measure of temporal clustering. Using the assumption that domestic indoor radon concentrations show annual cyclic behaviour, generally higher in the winter months than in summer, published data on seasonal variability of domestic radon concentration levels, in various areas of the UK, Europe, Asia and North America, are analysed. The results demonstrate significantly different annual variation profiles between domestic radon concentrations in different countries and between regions within a country, highlighting the need for caution in ascribing seasonal correction factors to extended geographical areas. The underlying geography, geology and meteorology of a region have defining influences on the seasonal variability of domestic radon concentration, and some examples of potential associations between the Gini Coefficient and regional geological and geographical characteristics are proposed. Similar differences in annual variation profiles are found for soil-gas radon measured as a function of depth at a common site, and among the activity levels of certain radon progeny species, specifically ²¹⁴Bi deposited preferentially in human body-fat by decay of inhaled radon gas. Conclusions on the association between these observed measures of variation and potential underlying defining parameters are presented.