The effect of aqueous aluminium on the amphipod Gammarus lacustris

Helt siden starten av 1900-tallet har man forsket på sur nedbør og hvilke effekter det har for naturen. Det har vært mange teorier om årsaken til at vann og vassdrag blir giftige etter å ha vært utsatt for sur nedbør. Tidligere forskning kom til slutt frem til at økte konsentrasjoner av aluminium i avrenningen til vann og vassdrag regnes som den mest alvorlige konsekvensen av sur nedbør. Det er også godt dokumentert at det er en sammenheng mellom aluminium i vannet og fiskedød. En grundig gjennomgang av litteraturen viser at det er gjort lite forskning på evertebrater og aluminium. Den begrensede forskningen som er gjort har ikke klargjort betydningen av aluminium for de enkelte artene, eller hvilke mekanismer som ligger bak giftvirkningen. Vi har i denne oppgaven tatt for oss arten marflo (Gammarus lacustris). Marflo er en tangloppe (Amphipoda) som regnes for å være svært følsom for lav pH, og det er tidligere registrert nedgang i antall bestander av marflo som følge av sur nedbør. I våre eksperimenter har vi brukt marflo for å finne svaret på om aluminium er like giftig for evertebrater som for fisk. Det ble utført tre forsøk hvor dyrene ble eksponert for fire forskjellige vanntyper, inkludert ubehandlet driftsvann (kontroll, pH 7,3); Surt Al-rikt vann med pH 5,8 (ustabil) ved å tilsette aluminiumnitrat (Al3NO3) og salpetersyre (HNO3), surt Al-rikt vann med pH 4,8 (stabil) ved å tilsette aluminiumnitrat og dobbelt så mye salpetersyre, og surt Al-fattig vann med pH 4,8 ved å tilsette bare salpetersyre. Hvert forsøk varte i 18 dager. Resultatene våre viser at det var en statistisk signifikant forskjell i dødelighet mellom de ulike vanntypene (p < 0,001 (log-rank)) i alle tre forsøkene. Dyrene eksponert for surt Al-rikt vann (stabil) og Surt Al-fattig vann hadde 100% dødelighet i alle forsøkene. I eksponeringene med surt Al-rikt vann (ustabil) var dødeligheten 8% i forsøk 1, 67% i forsøk 2 og 63% i forsøk 3. Dødeligheten i ubehandlet driftsvann var 8% i forsøk 1, 0% i forsøk 2 og 8% i forsøk 3. Våre resultater viser at ved pH 4,8 er det H+-konsentrasjonen i vannet som først og fremst har effekt på marflo. Vi finner ingen holdepunkter for at aluminium er mer giftig for marflo ved pH rundt 5,8 enn ved pH rundt 4,8, slik det er vist å være for fisk. Resultatene viser også at Al-polymersiering har stor betydning for effekten av surt Al-rikt vann på marflo ved pH 5,8, og at effekten er sammenlignbar med det som tidligere er vist for fisk. Aluminium synes å ha en viktig rolle når det gjelder effekten av sur nedbør på evertebrater generelt, og marflo spesielt. Aluminium kan se ut til å ha noe mindre betydning for effekten av sur nedbør for evertebrater sammenlignet med fisk.Since the beginning of the 20th century research has been conducted on acid precipitation and its effects on nature. Many theories have emerged as to why lakes and streams become toxic to aquatic animals after being exposed to acid precipitation. Previous research eventually concluded that the increase in concentration of aluminum in the water is considered the most serious consequence of acid precipitation. The correlation between aqueous aluminum and fish toxicity is well documented. A thorough review of the literature shows that little research has been conducted on invertebrates and aluminum. The research that has been conducted has not clarified the importance of aluminum or the mechanism behind the toxic effect on each of the species studied. In this study we have used the amphipod Gammarus lacustris in our experiments. G. lacustris is considered to be sensitive to low pH, previously there have been registrations of a decrease in the number of populations as a result of acid precipitation. We have performed three consecutive experiments were the animals were exposed to four different treatments, including untreated water (control, pH 7,3), acidic Al-rich water with pH 5,8 (unstable) by adding aluminum nitrate (Al3NO3) and nitric acid (HNO3) to the water, acidic Al-rich water with pH 4,8 (stable) by adding aluminum nitrate and twice as much nitric acid, and acidic Al-poor water with pH 4,8 by adding only nitric acid. The experiments lasted for 18 days. Our results show that there was a statistically significant difference in mortality between the waters tested (p < 0,001 (log-rank)). Animals exposed to acidic Al-rich water (stable) and acidic Al-poor water had a mortality of 100% in all three experiments. The mortality in the exposure to acidic Al-rich water (unstable) was 8% in experiment 1, 67% in experiment 2 and 63% in experiment 3. The mortality in the untreated water varied between 0 and 8%. At pH 4,8 the concentration of H+-ions is the primary reason to the effect on G- lacustris. We could not prove aluminum to be more toxic to G. lacustris at pH 5,8 than at pH 4,8, as it is for fish. Al-polymerization is of great importance for the effect of acidic Al-rich water on G. lacustris at pH 5,8, and the effect is comparable to that previously shown for fish. Aluminum appears to be of great importance to the effect of acidic precipitation on invertebrates in general, and G. lacustris in particular. Aluminum seems to have a little less significance for the effect of acidic precipitation on invertebrates compared to fish

A case-only approach for assessing gene-sex interaction in human longevity

As one aspect of the complex feature of longevity, gene-sex interaction plays an important role in influencing human life span. With advances in molecular genetics, more studies aimed at assessing gene-sex interaction are expected. New and valid statistical methods are needed. In this paper, we introduce a nontraditional approach, the case-only design, which was originally proposed for assessing gene and disease associations, to detect gene-sex interaction in human longevity. Applications of this method to data collected from centenarian studies show that it can produce consistent results as compared with results obtained from case-control and other approaches. Important features of the application in human longevity studies are highlighted and discussed. Since centenarians constitute a special population representing successful ageing, the easily applicable case-only approach will be an important tool for screening potential major genes that contribute to human longevity. (AUTHORS)

Weight trajectories and disordered eating behaviours in 11-to 12-year-olds:A longitudinal study within the Danish National Birth Cohort

To examine how childhood weight trajectories are associated with disordered eating behaviours (DEBs) in early adolescence

Immunological Memory Transferred with CD4 T Cells Specific for Tuberculosis Antigens Ag85B-TB10.4: Persisting Antigen Enhances Protection

BACKGROUND:High levels of death and morbidity worldwide caused by tuberculosis has stimulated efforts to develop a new vaccine to replace BCG. A number of Mycobacterium tuberculosis (Mtb)-specific antigens have been synthesised as recombinant subunit vaccines for clinical evaluation. Recently a fusion protein of TB antigen Ag85B combined with a second immunodominant TB antigen TB10.4 was emulsified with a novel non-phospholipid-based liposomal adjuvant to produce a new subunit vaccine, investigated here. Currently, there is no consensus as to whether or not long-term T cell memory depends on a source of persisting antigen. To explore this and questions regarding lifespan, phenotype and cytokine patterns of CD4 memory T cells, we developed an animal model in which vaccine-induced CD4 memory T cells could transfer immunity to irradiated recipients. METHODOLOGY/PRINCIPAL FINDINGS:The transfer of protective immunity using Ag85B-TB10.4-specific, CD45RB(low) CD62L(low) CD4 T cells was assessed in sub-lethally irradiated recipients following challenge with live BCG, used here as a surrogate for virulent Mtb. Donor T cells also carried an allotype marker allowing us to monitor numbers of antigen-specific, cytokine-producing CD4 T cells in recipients. The results showed that both Ag85B-TB10.4 and BCG vaccination induced immunity that could be transferred with a single injection of 3x10(6) CD4 T cells. Ten times fewer numbers of CD4 T cells (0.3x10(6)) from donors immunised with Ag85B-TB10.4 vaccine alone, transferred equivalent protection. CD4 T cells from donors primed by BCG and boosted with the vaccine similarly transferred protective immunity. When BCG challenge was delayed for 1 or 2 months after transfer (a test of memory T cell survival) recipients remained protected. Importantly, recipients that contained persisting antigen, either live BCG or inert vaccine, showed significantly higher levels of protection (p<0.01). Overall the numbers of IFN-gamma-producing CD4 T cells were poorly correlated with levels of protection. CONCLUSIONS/SIGNIFICANCE:The Ag85B-TB10.4 vaccine, with or without BCG-priming, generated TB-specific CD4 T cells that transferred protective immunity in mice challenged with BCG. The level of protection was enhanced in recipients containing a residual source of specific antigen that could be either viable or inert

Developing solid particulate vaccine adjuvants:surface bound antigen favouring a humoural response, whereas entrapped antigen shows a tendency for cell mediated immunity

This present study compares the efficacy of microsphere formulations, and their method of antigen presentation, for the delivery of the TB sub-unit vaccine antigen, Ag85B-ESAT-6. Microspheres based on poly(lactide-co-glycolide) (PLGA) and chitosan incorporating dimethyldioctadecylammonium bromide (DDA) were prepared by either the w/o/w double emulsion method (entrapped antigen) or the o/w single emulsion method (surface bound antigen), and characterised for their physico-chemical properties and their ability to promote an immune response to Ag85B-ESAT-6. The method of preparation, and hence method of antigen association, had a pronounced effect on the type of immune response achieved from the microsphere formulations, with surface bound antigen favouring a humoural response, whereas entrapped antigen favoured a cellular response

Persistent High Incidence of Tuberculosis in Immigrants in a Low-Incidence Country

Immigration from areas of high incidence is thought to have fueled the resurgence of tuberculosis (TB) in areas of low incidence. To reduce the risk of disease in low-incidence areas, the main countermeasure has been the screening of immigrants on arrival. This measure is based on the assumption of a prompt decline in the incidence of TB in immigrants during their first few years of residence in a country with low overall incidence. We have documented that this assumption is not true for 619 Somali immigrants reported in Denmark as having TB. The annual incidence of TB declined only gradually during the first 7 years of residence, from an initial 2,000 per 100,000 to 700 per 100,000. The decline was described by an exponential function with a half-time of 5.7 (95% confidence interval 4.0 to 9.7) years. This finding seriously challenges the adequacy of the customary practice of screening solely on arrival