Predicted impact of exotic vines on an endangered ecological community under future climate change

Potential interactions between climate change and exotic plant invasions may affect areas of high conservation value, such as land set aside for the protection of endangered species or ecological communities. We investigated this issue in eastern Australia using species distribution models for five exotic vines under climate regimes for 2020 and 2050. We examined how projected changes in the distribution of climatically suitable habitat may coincide with the remaining remnants of an endangered ecological community—littoral rainforests—in this region. The number of known infestations of each weed in tropical, subtropical and temperate areas was used to assess the likelihood of further expansion into areas projected to provide suitable habitat under future conditions. Littoral rainforest reserves were consistently predicted to provide bioclimatically suitable habitat for the five vines examined under both current and future climate scenarios. We explore the consequences and potential strategies for managing exotic plant invasions in these protected areas in the coming decades.     

Mitochondrial phylogeography and population history of pine martens Martes martes compared with polecats Mustela putorius

The flora and fauna of Europe are linked by a common biogeographic history, most recently the Pleistocene glaciations that restricted the range of most species to southern refugial populations. Changes in population size and migration, as well as selection, have all left a signature on the genetic differentiation. Thus, three paradigms of postglacial recolonization have been described, inferred from the patterns of DNA differentiation. Yet some species, especially wide-ranging carnivores, exhibit little population structuring between the proposed refugia, although relatively few have been studied due to the difficulty of obtaining samples. Therefore, we investigated mitochondrial variation in pine martens, Martes martes, in order to understand the extent to which they were affected by glacial cycles, and compared the results with an analysis of sequences from polecats, Mustela putorius. A general lack of ancient lineages, and a mismatch distribution that is consistent with an expanding population, is evidence that the present-day M. martes and Mu. putorius in central and northern Europe colonized from a single European refugium following a recent glaciation. There has also been interspecific mitochondrial introgression between M. martes and the sable M. zibellina in Fennoscandia.     

An intronic duplication in the alanine: glyoxylate aminotransferase gene facilitates identification of mutations in compound heterozygote patients with primary hyperoxaluria type 1

Summary We report here the identification of a duplication within the first intron of the gene encoding human alanine:glyoxylate aminotransferase (AGT); this duplication is closely linked to two point mutations associated with peroxisome-to-mitochondrion mistargeting of AGT in primary hyperoxaluria type 1 (PH1) patients. Polymerase chain reaction amplification of regions of the AGT gene including the insertion site from individuals heterozygous for this duplication, produces allele-specific fragments of different sizes. We have taken advantage of this to identify a nonsense mutation within a non-expressed allele of a compound heterozygote PH1 patient with mitochondrial AGT.     

Transfer of phospholipids by a protein fraction obtained from canine pulmonary lavage

Surfactant phospholipid exists in multicompartment pools within the subphase of the lung. Movement among these pools and back into type II alveolar cells may be catalyzed by a phospholipid transfer protein resident in the subphase. We demonstrate here that a protein fraction obtained from canine lung lavage catalyzes the intermembrane transfer of all the major surfactant phospholipids. The protein is probably not derived from serum and is unrelated to surfactant proteins that have already been described.     

Enzymological and mutational analysis of a complex primary hyperoxaluria type 1 phenotype involving alanine:Glyoxylate aminotransferase peroxisome-to-mitochondrion mistargeting and intraperoxisomal aggregation

Primary hyperoxaluria type 1 (PH1) is a rare autosomal recessive disease caused by a deficiency of the liver-specific peroxisomal enzyme alanine:glyoxylate aminotransferase (AGT). Three unrelated PH1 patients, who possess a novel complex phenotype, are described. At the enzymological level, this phenotype is characterized by a complete, or nearly complete, absence of AGT catalytic activity and reduced AGT immunoreactivity. Unlike normal individuals in whom the AGT is confined to the peroxisomal matrix, the immunoreactive AGT in these three patients was distributed approximately equally between the peroxisomes and mitochondria. The peroxisomal AGT appeared to be aggregated into amorphous core-like structures in which no other peroxisomal enzymes could be identified. Mutational analysis of the AGT gene showed that two of the three patients were compound heterozygotes for two previously unrecognized point mutations which caused Gly41→Arg and Phe152→Iso amino acid substitutions. The third patient was shown to be a compound heterozygote for the Gly41→Arg mutation and a previously recognized Gly170→Arg mutation. All three patients were homozygous for the Pro11→Leu polymorphism that had been found previously with a high allelic frequency in normal populations. It is suggested that the Phe152→Iso and Gly170→Arg substitutions, which are only eighteen residues apart and located in the same highly conserved internal region of 58 amino acids, might be involved in the inhibition of peroxisomal targeting and/or import of AGT and, in combination with the Pro11→Leu polymorphism, be responsible for its aberrant mitochondrial compartmentalization. On the other hand, the Gly41→Arg substitution, either in combination with the Pro11→Leu polymorphism or by itself, is predicted to be responsible for the intraperoxisomal aggregation of the AGT protein.     

Artificial nanovesicles for dsRNA delivery in spray-induced gene silencing for crop protection

Spray-induced gene silencing (SIGS) is an innovative and eco-friendly technology where topical application of pathogen gene-targeting RNAs to plant material can enable disease control. SIGS applications remain limited because of the instability of RNA, which can be rapidly degraded when exposed to various environmental conditions. Inspired by the natural mechanism of cross-kingdom RNAi through extracellular vesicle trafficking, we describe herein the use of artificial nanovesicles (AVs) for RNA encapsulation and control against the fungal pathogen, Botrytis cinerea. AVs were synthesized using three different cationic lipid formulations, DOTAP + PEG, DOTAP and DODMA, and examined for their ability to protect and deliver double stranded RNA (dsRNA). All three formulations enabled dsRNA delivery and uptake by B. cinerea. Further, encapsulating dsRNA in AVs provided strong protection from nuclease degradation and from removal by leaf washing. This improved stability led to prolonged RNAi-mediated protection against B. cinerea both on pre- and post-harvest plant material using AVs. Specifically, the AVs extended the protection duration conferred by dsRNA to 10 days on tomato and grape fruits and to 21 days on grape leaves. The results of this work demonstrate how AVs can be used as a new nanocarrier to overcome RNA instability in SIGS for crop protection.     

Distribution of pelagic larvae of benthic marine invertebrates in the Bellingshausen Sea

During November and December 1992, plankton samples were collected using a ring net of mesh size 200 m vertically hauled through a 600 m water column, at five stations along a transect running north from the Allison Peninsula in the Bellingshausen Sea. Three stations were located over the continental shelf; two of these were ice bound, whilst the third was at the ice edge. Two other stations were in deeper, ice-free water. Sixteen different larval and juvenile types were found representing seven phyla: Echinodermata, Nemertea, Coelenterata, Mollusca, Annelida, Arthropoda and Bryozoa, of which the first two were the most abundant. Larval numbers and types decreased with distance offshore and away from permanent sea ice. The presence of many stages of nemertean larval development within a short time scale, in an area where developmental tends to be slow, suggests that reproduction occurs over an extended period and that the larvae have a long planktonic phase. The increased size of later developmental stages of the nemertean larvae indicates they obtain nutrition within the water column during winter, when little particulate food is present.