The mode of action of the plant antimicrobial peptide MiAMP1 differs from that of its structural homologue, the yeast killer toxin WmKT

The plant antimicrobial peptide MiAMP1 from Macadamia integrifolia and the yeast killer toxin peptide WmKT from Williopsis mrakii are structural homologues. Comparative studies of yeast mutants were performed to test their sensitivity to these two antimicrobial peptides. No differences in susceptibility to MiAMP1 were detected between wild-type and several WmKT-resistant mutant yeast strains. A yeast mutant MT1, resistant to MiAMP1 but unaffected in its susceptibility to plant defensins and hydrogen peroxide, also did not show enhanced tolerance towards WmKT. It is therefore probable that the Greek key beta-barrel structure shared by MiAMP1 and WmKT provides a robust structural framework ensuring stability for the two proteins but that the specific action of the peptides depends on other motifs. (C) 2004 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.

Truthiness and falsiness of trivia claims depend on judgmental contexts

When people rapidly judge the truth of claims presented with or without related but nonprobative photos, the photos tend to inflate the subjective truth of those claims-a "truthiness" effect (Newman et al., 2012). For example, people more often judged the claim "Macadamia nuts are in the same evolutionary family as peaches" to be true when the claim appeared with a photo of a bowl of macadamia nuts than when it appeared alone. We report several replications of that effect and 3 qualitatively new findings: (a) in a within-subjects design, when people judged claims paired with a mix of related, unrelated, or no photos, related photos produced truthiness but unrelated photos had no significant effect relative to no photos; (b) in a mixed design, when people judged claims paired with related (or unrelated) and no photos, related photos produced truthiness and unrelated photos produced "falseness;" and © in a fully between design, when people judged claims paired with either related, unrelated, or no photos, neither truthiness nor falsiness occurred. Our results suggest that photos influence people's judgments when a discrepancy arises in the expected ease of processing, and also support a mechanism in which-against a backdrop of an expected standard-related photos help people generate pseudoevidence to support claims. (PsycINFO Database Record)

More from less? – Efficient water use for macadamias

Macadamias, adapted to the fringes of subtropical rainforests of coastal, eastern Australia, are resilient to mild water stress. Even after prolonged drought, it is difficult to detect stress in commercial trees. Despite this, macadamia orchards in newer irrigated regions produce more consistent crops than those from traditional, rain-fed regions. Crop fluctuations in the latter tend to follow rainfall patterns. The benefit of irrigation in lower rainfall areas is undisputed, but there are many unanswered questions about the most efficient use of irrigation water. Water is used more efficiently when it is less readily available, causing partial stomatal closure that restricts transpiration more than it restricts photosynthesis. Limited research suggests that macadamias can withstand mild stress. In fact, water use efficiency can be increased by strategic deficit irrigation. However, macadamias are susceptible to stress during oil accumulation. There may be benefits of applying more water at critical times, less at others, and this may vary with cultivar. Currently, it is common for macadamia growers to apply about 20-40 L tree-1 day-1 of water to their orchards in winter and 70-90 L tree-1 day-1 in summer. Research reported water use at 20-30 L tree-1 day-1 during winter and 40-50 L tree-1 day-1 in summer using the Granier sap flow technique. The discrepancy between actual water use and farmer practice may be due to water loss via evaporation from the ground, deep drainage and/or greater transpiration due to luxury water consumption. More irrigation research is needed to develop efficient water use and to set practical limits for deficit irrigation management.