The relationship of the female reproductive success of Eucalyptus globulus to the endogenous properties of the flower.

Low capsule and seed set is a major factor limiting seed production in Eucalyptus globulus seed orchards. Controlled pollination studies showed that the reproductive success (number of seeds produced per flower pollinated) was primarily determined by the female. We aimed to identify the factors contributing to the differences in reproductive success between female genotypes in terms of the physical and anatomical properties of the flower. We studied pairs of genotypes of high and low reproductive success from each of three races (Furneaux Group, Strzelecki Ranges and Western Otways) growing in a seed orchard. Controlled pollinations were performed on six females and along with flower physical measurements, pollen tube growth and seed set were assessed. Overall tree reproductive success was positively correlated with flower size, ovule numbers, style size, cross-sectional area of conductive tissue within the style (all of which were inter-correlated) and the proportion of pollen tubes reaching the bottom of the style. Significant positive correlations of reproductive success and flower physical properties between different ramets of the same genotypes across seasons suggests a genetic basis to the variation observed. The majority of pollen tube attrition occurred within the first millimetre of the cut style and appeared to be associated with differences in style physiology. When examined as pairs within races the difference in reproductive success for the Western Otways pair was simply explained by differences in flower size and the number of ovules per flower. Physical features did not differ significantly for the Strzelecki Ranges pair, but the proportion of pollen tubes reaching the bottom of the style was lower in the less reproductively successful genotype, suggesting an endogenous physiological constraint to pollen tube growth. The difference in reproductive success between the females from the Furneaux Group was associated with a combination of these factors.

Increased interleukin 6 concentrations in the absence and presence of HIV-1 infection in haemophilia.

AIMS: To measure IL-6 concentrations in asymptomatic HIV-1 antibody positive and negative haemophilic patients and to correlate these with IgG concentrations and CD4 positive cell numbers. METHODS: IL-6 concentrations were measured by bioassay in stored serum from a prospective cohort of haemophilic patients in whom immunoglobulins and T cell subsets had been determined. Values of IL-6 and immunoglobulins were also correlated with severity of liver disease. RESULTS: IL-6 concentrations were raised in haemophilic patients independent of HIV-1 antibody status. In HIV-1 antibody positive patients there was no correlation between IL-6 concentrations and CD4 positive cell numbers, but there was a correlation with IgG (r = 0.4; p = 0.05). In HIV-1 antibody negative patients there were no significant correlations. CONCLUSIONS: Haemophilic patients have increased IL-6 concentrations; in HIV-1 positive patients this is independent of the decline in CD4 cell count. The raised concentrations do not correlate with the clinical severity of liver disease.