Novel strategies for assessing and managing the risks posed by invasive alien species to global crop production and biodiversity

International actions to combat the threat posed by invasive alien species (IAS) to crops and biodiversity have intensified in recent years. The formulation of 15 guiding principles on IAS by the Convention on Biological Diversity (CBD) stimulated the International Plant Protection Convention (IPPC) to review its role in protecting biodiversity. IPPC standards now demonstrate clearly that the risks posed by any organism that is directly or indirectly injurious to cultivated or uncultivated plants can be assessed and managed under the IPPC. Since the IPPC, unlike the CBD, constitutes an international legal instrument recognised by the World Trade Organization, greater protection from the introduction of IAS is now available. However, phytosanitary measures can only be enacted if they can be justified by risk analysis and we outline some novel strategies to improve the assessment and management of the risks posed by IAS, highlighting some of the key challenges which remain.     

pathmatrix: a geographical information system tool to compute effective distances among samples

pathmatrix is a tool used to compute matrices of effective geographical distances among samples using a least‐cost path algorithm. This program is dedicated to the study of the role of the environment on the spatial genetic structure of populations. Punctual locations (e.g. individuals) or zones encompassing sample data points (e.g. demes) are used in conjunction with a species‐specific friction map representing the cost of movement through the landscape. Matrices of effective distances can then be exported to population genetic software to test, for example, for isolation by distance. pathmatrix is an extension to the geographical information system (GIS) software arcview 3.x.     

Antarctic nemerteans: Heteronemertea– descriptions of new taxa, reappraisals of the systematic status of existing species and a key to the heteronemerteans recorded south of latitude 50oS

Twenty-three species representative of 15 heteronemertean genera are recorded from Antarctic and Subantarctic waters south oflatitude 50^oS. Five new genera are established and seven new species are fully described and illustrated. These are Cephalurichus antarcticus gen. et sp. nov., Dokonemertes magellanensis gen. et sp. nov., Dokonemertes macquariensis sp. nov., Micrellides multiperula gen. et sp. nov., Paramicrurinella falklandica gen. et sp. nov., Parborlasia landrumae sp. nov. and Zodionemertes chilensis gen. et sp. nov. Baseodiscus antarcticus Baylis, Antarctolineus scotti (Baylis), Lineus longifissus (Hubrecht) and Parborlasia fueguina Serna de Esteban & Moretto are redescribed and illustrated and the nature of rhynchodaeal pouches protruding into the cephalic blood lacunae of Parborlasia corrugatus (Mcintosh) is reexamined and discussed. The main anatomical characters of the remaining 11 species are recorded and it is concluded that of these only Parapolia grytvikenensis Wheeler, Cerebratulus malvini Wheeler, Chilineus glandulosa (Burger), Huilkia ushuaiensis Serna de Esteban & Moretto, Micrura pacifica Friedrich and Wiolkenia friedrichi Serna de Esteban & Moretto can at present be accepted as valid, although incompletely described, taxa. Cerebratulus larseni Wheeler, Cerebratulus validus Bürger, Lineus autrani Joubin and Lineus turqueli Joubin are so poorly and inadequately described that their taxonomic status cannot be verified, and the recorded occurrence of Lineus nigricans Burger in southern latitudes cannot be substantiated on the available evidence. Maps showing the recorded distribution of all the species are included and a key to the 18 validated species is provided.     

Nemerteans of the Great Barrier Reef 6. Enopla Hoplonemertea (Polystilifera: Reptantia)

Two new genera and species of reptantic polystiliferous hoplonemerteans from the Great Barrier Reef province of Australia are described and illustrated. Urichonemertes pilorhynchus gen. et sp. nov. and Xenonemertes rhamphocephalus gen. et sp. nov. are both placed in the family Drepanophoridae (Polystilifera: Eureptantia: Aequifurcata).     

Failure of Neuraminidase to unmask Histocompatibility Antigens on Trophoblast

DURING outbred pregnancy the mother is exposed to genetically foreign tissue because the offspring inherits transplantation antigens from the father. The survival of the foetus is ensured by the intervention of the trophoblast which does not express transplantation antigens between mother and foetus: mouse trophoblast is not rejected even when transplanted into immune recipients^1,3. The mechanism of this failure to express histocompatibility antigens is not understood^1–4, but Kirby et al. have suggested that the extracellular fibrinoid surrounding trophoblast cells is involved^5,6. Currie has suggested that the thick sialomucinous glycocalyx of the trophoblast cell might “mask” the histocompatibility antigens on the trophoblast^7,8 and has demonstrated that neuraminidase unmasked these antigens⁸. Our experiments, however, show that trophoblast incubated with neuraminidase cannot sensitize allogeneic mice to donor histocompatibility antigens. Furthermore, pretreatment of trophoblastic implants with neuraminidase did not interfere with their proliferation and growth in highly immune allogeneic recipients.     

Polynucleotide Ligase and φX174 Single Strand Synthesis

A DNA ligase mutant of E. coli when infected with φX174 produces linear single strands which appear in an intracellular pool and in phage particles. The linear single strands, which are infectious in a spheroplast assay, seem to be a normal intermediate in progeny DNA synthesis.     

Inhibitors of the RNA and DNA Dependent Polymerase Activities of RNA Tumour Viruses

RNA viruses of several animal leukaemias and sarcomas possess what seems so far to be a unique enzyme—an RNA dependent DNA polymerase^1–6. Specific inhibitors of the viral enzyme will not only be useful in the analysis of its possible role in neoplasia, but might provide drugs for leukaemia and cancer therapy.     

A phylogenetic analysis of subtribe Pleurothallidinae (Orchidaceae)

A cladistic analysis of subtribe, Pleurothallidinae (Orchidaceae) is based on 45 anatomical/ morphological characters. The ingroup members comprise 24 genera; the large genus Pleurothallis consists of two subgenera and ten species complexes. Three taxa representing subtribes Laeliinae and Arpophyllinae are designated as outgroup. Eight most parsimonious trees were discovered using computer assisted software (length = 230; CI = 0.27). The hypothesis that subtribe Pleurothallidinae has undergone a unilinear reduction in the number of pollinia is not supported by this study. Although the eight-pollinia state as represented by Octomeria apparently is plesiomorphic, the two-pollinia and four-pollinia states arose early in the phylogeny of the subtribe. Both two-and four-pollinia states subsequently reappeared as parallelisms. The six-pollinia state exhibited in Brachionidium is autapomorphic. This cladistic analysis suggests that Pleurothallis is not a natural genus and, perhaps may be divided into several discrete genera.