Identification and functional characterization of the Arabidopsis Snf1‐related protein kinase SnRK2.4 phosphatidic acid‐binding domain

Phosphatidic acid (PA) is an important signalling lipid involved in various stress‐induced signalling cascades. Two SnRK2 protein kinases (SnRK2.4 and SnRK2.10), previously identified as PA‐binding proteins, are shown here to prefer binding to PA over other anionic phospholipids and to associate with cellular membranes in response to salt stress in Arabidopsis roots. A 42 amino acid sequence was identified as the primary PA‐binding domain (PABD) of SnRK2.4. Unlike the full‐length SnRK2.4, neither the PABD‐YFP fusion protein nor the SnRK2.10 re‐localized into punctate structures upon salt stress treatment, showing that additional domains of the SnRK2.4 protein are required for its re‐localization during salt stress. Within the PABD, five basic amino acids, conserved in class 1 SnRK2s, were found to be necessary for PA binding. Remarkably, plants overexpressing the PABD, but not a non‐PA‐binding mutant version, showed a severe reduction in root growth. Together, this study biochemically characterizes the PA–SnRK2.4 interaction and shows that functionality of the SnRK2.4 PABD affects root development.     

The effect of Tropical Cyclone Larry on tooth‐billed bowerbird Scenopoeetes dentirostris court attendance and decoration

Abstract The effect of Severe Tropical Cyclone Larry on tooth‐billed bowerbird court attendance and decoration was assessed for 32 courts located on the southern Atherton Tablelands. Numbers of active courts and the number of leaves on courts were compared with the two previous court attendance seasons. Compared with the 2004/2005 and 2005/2006 seasons, when court attendance was well established by mid‐September, tooth‐billed bowerbirds commenced court attendance late in the 2006/2007 season that followed Cyclone Larry. There were no courts active in mid‐September, and few were active in the first week of October. Twenty‐five percent fewer courts were active over the course of the 2006/2007 season than in the 2005/2006 season. For most of the 2006/2007 season, the average number of leaves on courts was significantly lower than in the previous two seasons. The 2006/2007 tooth‐billed bowerbird court attendance season appears to have been affected by direct disturbance to court sites and by the fruit shortage that followed the cyclone.     

The impact of Tropical Cyclone Larry on bird communities in fragments of the endangered rainforest Type 5b

Abstract Bird surveys were conducted to assess the impact of a severe cyclone on bird communities in three fragments of the endangered rainforest Type 5b on the Atherton Tablelands of far north Queensland. Bird communities were surveyed using timed area searches in three sites in each of the three fragments and were undertaken prior to and following Tropical Cyclone Larry. Cyclone Larry caused short‐term changes in the abundance of some species of birds in Type 5b rainforest fragments. Two weeks after the storm, in two of three fragments surveyed, abundance of the frugivorous wompoo fruit‐dove (Ptilinopus magnificus) and figbird (Sphecotheres viridis) had decreased while the omnivorous Macleay's honeyeater (Xanthotis macleayana) and Lewin's honeyeater (Meliphaga lewinii) decreased in abundance in all three locations. Most insectivorous species increased in some sites and decreased in others following Cyclone Larry. Rapid recovery of bird communities to approximately their pre‐cyclone state after only 7 months appeared to reflect the capacity of species to either modify their foraging behaviour, switch foods, or to move within or between fragments or to other food sources in the landscape.     

Mobilization of Reserves and Synthesis of Sterols and Triterpenes in Seedlings of Two Canarian Euphorbia Species

Seedlings from Euphorbia canariensis and Euphorbia lambii weregrown in the dark at 25 °C. Protein and triglyceride contentas well as levels of sugars and amino acids in the endospermwere determined during endosperm depletion. In the endospermof Euphorbia canariensis, relatively low levels of amino acids(up to 1 µmol.endosperm^–1) were found of which glutamine/glutamateaccounted for 40% at the stage of radicle emergence. High levelsof amino acids (up to 4 µmol.endosperm^–1) comparedwith sugars (up to 2 µmol sucrose.endosperm^–1) weredetected in the endosperm of Euphorbia lambii. Arginine wasthe main component (28 µmol%) of the amino acids in thistissue. In both species amino acid composition changed graduallyduring endosperm depletion. Cotyledons retained their ability to absorb a variety of watersoluble substrates after removal of the endosperm. ¹⁴C from[U-¹⁴C]sucrose was effectively incorporated into the triterpenesof the laticifers and to a lesser extent into the sterols ofthe seedling. The highest incorporation values were found inyoung seedlings about 2 d after the emergence of the radicle.Seedlings of this age also showed high incorporation rates of¹⁴C from labelled alanine, serine, threonine, valine, leucineand isoleucine into both triterpenols and sterols, but no generalconclusions about metabolic channelling in lipid synthesis couldbe made. Endosperm, Euphorbia canariensis L. Euphorbia lambii Svent., sterols, triterpenols, amino acids, laticifer, biosynthesis     

Differences in intestinal microbiota between avian brood parasites and their hosts

The intestinal microbiota determines the effectiveness of digestion in vertebrates, and is influenced by the external environment (mainly the diet), gut characteristics, and phylogeny. Avian brood-parasitic nestlings of the sub-family Cuculinae develop in nests of phylogenetically distant passerines and can be fed with the host diet. If the shaping of bacterial communities is dominated by phylogenetic constraints, and therefore the microbiota of parasitic nestlings differs from that of host nestlings, the energy and micronutrients that parasites and hosts obtain from a similar amount of food would be different. In this case, the bacterial communities of parasitic and host nestlings would have important consequences with respect to brood parasite development. By experimentally creating mixed broods of magpies ( Pica pica ) and great spotted cuckoos ( Clamator glandarius ), we investigated their cloacal microbiota using ribosomal intergenic spacer analysis. We found significant differences in bacterial assemblages of the parasitic and host nestlings, although none of the phylotypes were specific in either great spotted cuckoos or magpies. Cuckoos presented more complex communities, which could help the brood parasitic life style and allow the digestion of food provided by different potential hosts. Moreover, the intestinal morphology is different between the two species due to phylogenetic differences in the two taxa, which would influence the dissimilar bacterial assemblages. The detected differences in microbiota of great spotted cuckoo and magpie nestlings, which might occur in other brood parasite–host systems, may imply a lower digestion efficiency in parasites. Thus, the higher level requirements of cuckoo nestlings may be explained, at least in part, by cuckoos having a suboptimal bacterial community for processing the host diet.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 406–414.