Environmental and seasonal influences on red raspberry flavour volatiles and identification of quantitative trait loci (QTL) and candidate genes

Raspberry volatiles are important for perceptions of sensory quality, mould resistance and some have nutraceutical activities. Twelve raspberry character volatiles were quantified, 11 of them in fruit from two seasons, from plants from the Glen Moy × Latham mapping population growing in both open field and under cover (polytunnels). Effects of season and environment were examined for their impact on the content of α-ionone, α-ionol, β-ionone, β-damascenone, linalool, geraniol, benzyl alcohol, (Z)-3-hexenol, acetoin, acetic and hexanoic acids, whilst raspberry ketone was measured in one season. A significant variation was observed in fruit volatiles in all progeny between seasons and method of cultivation. Quantitative trait loci were determined and mapped to six of the seven linkage groups, as were candidate genes in the volatiles pathways.     

The Peoples of the Middle Niger: The Island of Gold

The Peoples of the Middle Niger: The Island of Gold. Roderick J. Mclntosh. Williston, VT: Blackwell, 1998. 346 pp.     

Geographical distributions in tropical trees: can geographical range predict performance and habitat association in co‐occurring tree species?

Aim A major floristic and climatic transition from aseasonal to seasonal evergreen tropical forest (the Kangar–Pattani Line; KPL) exists in the Indo‐Sundaic region of Southeast Asia. Mechanisms constraining species distribution here are at present poorly understood, but it is hypothesized that species differ in their tolerances of abiotic factors, in particular water availability. Under this hypothesis, we anticipate differences in performance or habitat preferences, or both, of species differing in distribution with respect to the KPL. The aim of this study is to test whether geographical distributions can be used to explain variation in growth, mortality and habitat preferences in co‐occurring tree species differing in their distribution in relation to the KPL. Location Pasoh Forest Reserve, Negeri Sembilan, Malaysia; south of the KPL. Methods All tree species within a 50‐ha forest dynamics plot were classified as widespread or southern based upon their distributions in relation to the KPL and as habitat specialists or generalists based on spatial association with soil‐based habitat categories. Growth and mortality rates, variation in growth and mortality with respect to soil type, and levels of habitat association were quantified for species with different geographical distributions. Results Differences existed in species performance based upon geographical distributions. Specifically, widespread species had lower growth rates than did species restricted to the aseasonal forests. Mortality rates did not differ as a function of geographical distribution. The growth responses of species to soil habitats also diverged, such that differences in performance of widespread species among soil types were more conservative than those of species restricted in their distribution to the aseasonal forests. However, the proportion of species showing positive habitat associations did not differ significantly between widespread and southern species. Main conclusions Distribution‐based differences in species performance and response to soil type support the hypothesis that species tolerant of wider climatic variation perform less well in any given environment due to limitations on plasticity. These performance differences provide quantitative evidence of the role of climatic transitions in determining tree species distributions in relation to the Kangar–Pattani Line in the Indo‐Malay region. Such differences in performance have important implications for our understanding of biodiversity gradients and responses of Indo‐Sundaic forests to climate change.     

In vitro antimicrobial activity against Pseudomonas aeruginosa and acute oral toxicity of marine algae Gracilaria changii

Methanol extract of the Gracilaria changii has been screened for antimicrobial activity against Pseudomonas aeruginosa. Antimicrobial activities were carried out using disc diffusion assay and broth dilution method against P. aeruginosa. The methanol extract of G. changii showed a good antimicrobial activity against P. aeruginosa with MIC (Minimum Inhibitory Concentration) value of 6.25 mg/ml. Exposure of P. aeruginosa cells to 6.25 mg/ml of methanol extract of G. changii resulted in complete inhibition of the bacterial cells. The main abnormalities noted via SEM and TEM studies were the alterations in morphology and cytology of the bacterial cells. The main reason for this deterioration was discussed. The effect of the methanol extract on the growth profile for the bacteria was also done and confirmed the bactericidal effect of the G. changii methanol extract on P. aeruginosa by changing the normal growth profile of P. aeruginosa. In an acute toxicity study using mice, the median lethal dose (LD₅₀) of the extract was greater than 2000 mg/kg, and we found no pathological changes in macroscopic examination by necropsy of mice treated with extract. We conclude that G. changii might be safely used as an antimicrobial agent.     

New diprenylated dihyrochalcones from leaves of Artocarpus elasticus

Two new diprenylated dihydrochalcones, elastichalcone A 1 and elastichalcone B 2 and three known compounds were isolated from the leaves of Artocarpus elasticus. Their structures were determined by various spectroscopic techniques (UV, IR, MS, 1D-NMR and 2D-NMR). Elastichalcone B 2 and a known compound exhibited good free radical scavenging activity with IC₅₀ values of 11.30 and 11.89 μg/ml, respectively.     

Excluding blood donors at high risk of HIV infection in a west African city.

OBJECTIVE--To examine the potential impact of deferral of blood donors at high risk of HIV infection in a west African city where blood is screened for HIV antibodies but no other special measures are taken to protect the blood supply. DESIGN--Cross sectional study. SETTING--National Blood Transfusion Centre and Project RETRO-CI, an international collaborative AIDS research project, Abidjan, Côte d''Ivoire. SUBJECTS--1257 male first time blood donors. INTERVENTIONS--Blood donors were interviewed about demographic and behavioural characteristics and tested for HIV antibodies by enzyme immunoassay and, if positive, synthetic peptide based tests. MAIN OUTCOME MEASURES--HIV antibody status in relation to presence of behavioural risk factors; calculation of sensitivity, specificity, and predictive values of specific criteria for excluding HIV infected donors. RESULTS--The overall prevalence of HIV infection was 11.4%. The most important risk factors for HIV positivity were prostitute contact and being aged 30-39 years. For identifying seropositive donors individual criteria had sensitivity, specificity, and positive predictive values ranging from 15% to 98%, 38% to 91%, and 17% to 30% respectively. Prostitute contact in the past five years would have excluded 31% of all donors and 73% of HIV infected donors. 27% of those excluded would have been HIV positive. CONCLUSIONS--The widespread assumption that donor deferral is not feasible in sub-Saharan Africa needs reassessment. In Abidjan this approach was well accepted and potentially effective. Donor deferral requires evaluation as a strategy for improving blood safety in resource poor areas with high rates of HIV infection.     

Quantitative observations on the pulmonary anatomy of the domestic Muscovy duck (Cairina moschata)

The lungs of five female domestic Muscovy ducks, mean body weight 1.627 kg, total lung volume 48.07 cm³, were analysed by standard morphometric methods. Principal results obtained are: lung volume per unit body weight, 30.17 cm³/g; volume densities of exchange tissue relative to lung volume, 49.24%, blood capillaries relative to exchange tissue, 29.63%, tissue of the blood gas (tissue) barrier relative to exchange tissue, 5.88%; surface area of the blood-gas (tissue) barrier per unit body weight, 30.04 cm²/g; ratios of the surface area of the blood-gas (tissue) barrier per unit volume of the lung and per unit volume of exchange area, 979 cm²/cm³ and 200.06 mm²/mm³, respectively; harmonic and arithmetic mean thicknesses of the tissue barrier, 0.199 μm and 0.303 μm, respectively. The anatomical diffusing capacity of the tissue barrier for oxygen ( DtO₂ ) and the total pulmonary diffusing capacity ( DLO₂ ), 49.58 ml O₂/min/mmHg/kg and 4.55 ml O₂/min/mm Hg/kg, respectively. The lungs of the domestic Muscovy duck appear to be about as well adapted anatomically for gas exchange as the lungs of wild anatid species, and there is no clear evidence that domestication has been associated with any deterioration in the anatomical capacity for oxygen uptake. The weight-specific anatomical diffusing capacity of the lung for oxygen ( DLO₂/W ) was about 3.6 times greater than the weight-specific physiological value, a factor which falls within the expected range.     

Population genetics and symbiont assemblages support opposing invasion scenarios for the red turpentine beetle (Dendroctonus valens)

Exotic forest insects and their symbionts pose an increasing threat to forest health. This is apparently true for the red turpentine beetle (Dendroctonus valens), which was unintentionally introduced to China, where the beetle has killed millions of healthy native pine trees. Previous population genetics studies that used cytochrome oxidase I as a marker concluded that the source of D. valens in China was western North America. In contrast, surveys of fungi associated with D. valens demonstrated that more fungal species are shared between China and eastern North America than between China and western North America, suggesting that the source population of D. valens could be eastern North America. In this study, we used microsatellite markers to determine population structure of D. valens in North America as well as the source population of the beetle in China. The analyses revealed that four genetically distinct populations (herein named the West, Central, Northeast and Mexico) represent the native range of D. valens. Clustering analyses and a simulation‐based approximate Bayesian computation (ABC) approach supported the hypothesis that western North America is the source of the invasive D. valens population. This study provides a demonstration of non‐congruence between patterns inferred by studies on population genetics and symbiont assemblages in an invasive bark beetle.     

Influence of climatic factors on tree growth in riparian forests in the humid and dry savannas of the Volta basin,Ghana

Key message

The paper demonstrates the prospects and applications of dendrochronology for understanding climate change effects on riparian forests in the savanna landscape. 

Abstract

Riparian trees in savannas have a potential for dendro-climatic studies, but have been neglected hitherto. We examined ring-width series of Afzelia africana (evergreen) and Anogeissus leiocarpus (deciduous) to study the influence of climatic factors on the growth of riparian trees in the humid (HS) and dry (DS) savanna zones of the Volta basin in Ghana. A total of 31 stem discs belonging to A. africana and A. leiocarpus were selected from HS and DS to establish species-specific local chronologies of tree growth. Each individual of A. africana and A. leiocarpus from the two savanna sites showed distinct growth rings. Cross-dating of individual tree-ring patterns was successful using standard dendrochronological techniques. The mean annual growth rates of A. africana in the HS (1.38 ± 0.09) and DS (1.34 ± 0.08) were not statistically different. Furthermore, mean annual growth rate of A. leiocarpus in the DS (3.75 ± 0.27) was higher than in the HS (2.83 ± 0.16) suggesting that species in drier environment can have higher growth rates when sufficient soil moisture is available. The growth rates of both species at the same sites were different, which might indicate different water use strategies. High correlations of individual tree-ring series of A. africana and A. leiocarpus trees at HS and DS suggest a strong climatic forcing controlled by the seasonal movement of the inter-tropical convergence zone. The annual growth of A. africana and A. leiocarpus at both the HS and DS was significantly correlated with local temperature and precipitation. The negative correlations of the growth of the two tree species to global sea surface temperatures were however, indications that the growth of riparian forests can be impacted during El Niño-Southern Oscillation years. The result of our study shows that riparian trees in the humid and dry savanna zones of West Africa can be successfully used for dendrochronological studies.