The non-native vascular flora of the Falkland Islands

Summary

Non-native species form a significant, but under-recorded, component of the Falkland Islands vascular flora. With this in mind a comprehensive re vie w of the non-native flora of the Falkland Islands was undertaken for the first time since the publication of the definitive Flora in 1968. We have recorded 175 non-native taxa, from 46 families, from the Falkland Islands which are listed with accompanying notes on habitat, status and distribution. Twenty-nine of these are likely to be commonly encountered, though only Aira praecox, Cerastium fontanum, Rumex acetosella and Sagina procumbens are near ubiquitous throughout. The origins of much of the non-native flora are obscure, however most species seem to be of European descent, and a significant proportion of taxa seem to have become established after introductions for agricultural and horticultural purposes.     

Staphylococcus aureus nuclease is a useful secretion reporter for mycobacteria.

A secretion reporter system based on Staphylococcus aureus nuclease (nuc) was developed for use in mycobacteria. Fusion of secretion signals to the reporter cloned in a shuttle vector, pBPnuc1, resulted in halo formation around colonies of Mycobacterium smegmatis and Mycobacterium tuberculosis grown on DNase agar plates containing Methyl Green indicator dye. This in-situ detection system was used to identify secreted proteins by screening a pBPnuc1::H37Rv nuc gene fusion library in M. smegmatis. The clones identified in this screen all formed colony halos when present in M. tuberculosis grown on indicator media. The proteins corresponded to DesA2, a stearoyl-acyl carrier protein desaturase, PepA, a putative serine protease and the Apa antigen, which is the ATP-binding subunit of an ABC transport system. Of these proteins, only PepA and Apa contained recognizable leader peptides.     

Isoprenylated resorcinol derivatives from Glycyrrhiza acanthocarpa

The ether extract of leaves and terminal branches of Glycyrrhiza acanthocarpa afforded four new isoprenylated resorcinol derivatives. Two of these are isoprenologues of cannabigerol and cannabigerolic acid.     

Familiar Neighbors,but Not Relatives,Enhance Fitness in a Territorial Mammal

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Natural cytotoxicity in AKR/J mice during adjuvant induced amyloidogenesis

The induction of amyloidosis in AKR mice has previously been shown to be associated with a decrease in the incidence of spontaneous thymic leukemia (P. Ebbesen, Brit. J. Cancer29, 76, 1974). Amyloid induction with azocasein depresses the activity of the natural killer (NK) cell, a cell believed to be important in the protection against the development of malignancy. In the present studies, therefore, we examined the response of the NK cell to the induction of amyloidosis in AKR mice. Rapid and long-term depression of NK cell activity against YAC-1 tumor cells was noted following intraperitoneal administration of complete Freund's adjuvant enriched with Mycobacterium butyricum. Mixing studies suggested that active suppression did not account for the observed decrease in NK cell activity. Although some NK cell activity was noted in ascitic fluid, redirection was not felt to account for the rapid and dramatic reduction in splenic NK cell activity. Furthermore, serum from adjuvant-treated but not control mice was found to significantly inhibit NK cell activity in vitro. These studies therefore suggested a role for a serum factor in the depression of this activity. The apparent paradox of decreased NK cell activity in a setting of diminished leukemogenesis is considered in relation to previous studies describing impaired T-cell functioning after the induction of amloidosis.