Summary• The effect is reported here of cytochalasin E isolated from the fungus Rosellinia necatrix on photosynthesis in young leaves of Malus domestica (apple).• Cytochalasin E was administered via the petiole to excised leaves. The chlorophyll fluorescence emission spectrum and time resolved fluorescence decay were measured up to the point where visible leaf damage was observed.• Within 2 h, the ratio of fluorescence emission at 730 nm decreased with respect to the peak at 690 nm. Over 6 h a small blue shift in the 690 nm emission band to 685 nm was seen. The time resolved fluorescence decay showed changes over a similar timescale after administration of cytochalasin E. The control decay could be fitted by two components, τ 1 , 112 ps, τ 2 , 402 ps, but after 6 h treatment with cytochalasin E the decay required a further component τ 3 , 4.25 ns for a good fit.• Cytochalasin E has a direct effect on photosynthesis, possibly as a result of impairment of light harvesting. This might partially account for the pathogenicity of the root infecting R. necatrix . Fluorescence techniques may therefore provide an early detection system for the fungus, a necessary prerequisite for development of a control strategy.
A common limitation to most forensic trace evidence analysis is the ability to determine the time at which the evidence was deposited at the crime scene. This issue of timing is vitally important as it may not only reveal when the crime occurred, but could exclude potential suspects from the investigation. Using a reverse transcription quantitative polymerase chain reaction (RT-qPCR) assay, we monitored the relative expression ratio (RER) of two different RNA species (18S and β-actin) in hair samples that were aged naturally over a period of 3 months. No gender or age-of-donor biases were observed, and results were linear up to 60 days. After 60 days, the results were more variable and gave unreliable estimates of time since deposition. Overall, the results presented in this paper suggest that the age of hair samples containing follicular tags can be approximated using a second-order polynomial, although with limitations: Age = 3.31RER(2) - 2.85RER - 0.54 (R(2) = 0.98).
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