Amyloids - A functional coat for microorganisms

Amyloids are filamentous protein structures ~10 nm wide and 0.1–10 µm long that share a structural motif, the cross-β structure. These fibrils are usually associated with degenerative diseases in mammals. However, recent research has shown that these proteins are also expressed on bacterial and fungal cell surfaces. Microbial amyloids are important in mediating mechanical invasion of abiotic and biotic substrates. In animal hosts, evidence indicates that these protein structures also contribute to colonization by activating host proteases that are involved in haemostasis, inflammation and remodelling of the extracellular matrix. Activation of proteases by amyloids is also implicated in modulating blood coagulation, resulting in potentially life-threatening complications.

Strategies for the Use of Fallback Foods in Apes

Researchers have suggested that fallback foods (FBFs) shape primate food processing adaptations, whereas preferred foods drive harvesting adaptations, and that the dietary importance of FBFs is central in determining the expression of a variety of traits. We examine these hypotheses in extant apes. First, we compare the nature and dietary importance of FBFs used by each taxon. FBF importance appears greatest in gorillas, followed by chimpanzees and siamangs, and least in orangutans and gibbons (bonobos are difficult to place). Next, we compare 20 traits among taxa to assess whether the relative expression of traits expected for consumption of FBFs matches their observed dietary importance. Trait manifestation generally conforms to predictions based on dietary importance of FBFs. However, some departures from predictions exist, particularly for orang-utans, which express relatively more food harvesting and processing traits predicted for consuming large amounts of FBFs than expected based on observed dietary importance. This is probably due to the chemical, mechanical, and phenological properties of the apes’ main FBFs, in particular high importance of figs for chimpanzees and hylobatids, compared to use of bark and leaves—plus figs in at least some Sumatran populations—by orang-utans. This may have permitted more specialized harvesting adaptations in chimpanzees and hylobatids, and required enhanced processing adaptations in orang-utans. Possible intercontinental differences in the availability and quality of preferred and FBFs may also be important. Our analysis supports previous hypotheses suggesting a critical influence of the dietary importance and quality of FBFs on ape ecology and, consequently, evolution

Management of lucerne in the cool season

Paper presented at the 52nd New Zealand Grassland Association Conference, 30 October - 1 November 1990, Ashburton.The performance of dormant and winter-active lucerne (Medicago sativa L.) cultivars was compared under sheep grazing in 2 experiments during the cool season. The objectives were to define the cool season management required for winter-active cultivars in sheep farming systems. The ‘winter-active cultivars Matador and Rere yielded 1760 and 1220 kg DM/ha compared with 890 and 760 kg from Wairau and Saranac respectively in mid-winter, while the reverse occurred in spring when dormant cultivars yielded 50% more than the winter active. This was related to differing levels of non-structural carbohydrates in roots, which had declined to insignificant levels in Rere and Matador by early spring. June grazing increased spring yields of Wairau by 35% due to control of overwintering aphids, but reduced yield of Rere by 25% due to effects on root reserves. Early September grazing greatly reduced subsequent lucerne yields at late October and early December grazings, and increased the content of weeds. Our findings show that if farmers graze winter-active lucerne with sheep in winter the advantage in production disappears in spring. Cool-season management which combines the use of dormant and winter-active lucernes is discussed

Nutrient storage in roots and rhizomes of hexaploid Caucasian clover

Paper presented at the 56th New Zealand Grassland Association Conference, 17-20 October 1994, Hanmer Springs.Hexaploid Trifolium ambiguum M. Bieb. (Caucasian clover cv. Prairie) persisted and dominated in high country plots which received more than 100 kg P/ha at establishment. After 13 years the biomass of coarse roots (rhizomes and tap-roots) amounted to 20 t/ha. The contents of nutrients in the root fractions were approximately five times that in the herbage. This ability to retain nutrients in coarse roots may be a strategy that contributes to the dominance of Caucasian clover on this acid soil

Long-term experiments in the South Island high country: an example from Mt. Possession, Canterbury

Paper presented at the 56th New Zealand Grassland Association Conference, 17-20 October 1994, Hanmer Springs.This paper discusses the successional changes that have occurred during 13 years of a designed experiment in short tussock grassland. The ‘experiment site is at Mt. Possession Station, Canterbury and was established in 1979. Nine species of legume were overdrilled and 9 phosphate rates (O-800 kg P/ha) broadcast at sowing. A vegetation survey of all plots was carried out in November 1991 and soil sampled in the following year. Legumes were dominant during the early years of the experiment but the responses to P rates differed. Some of the differences in the present vegetation could be explained by earlier treatment effects. Exotic grasses invaded the plots which received higher levels of fertiliser with the exception of plots sown with Lupinus species where grass growth was independent of the applied P rate. The initial treatments have strongly affected present vegetation. Had an attempt been made at the beginning to predict the current composition, or even half way through the experiment, the conclusions are unlikely to have been realistic. It is suggested that the dynamics and composition of the responses are inter-related and complex, and as such, they require long-term monitoring before any predictions can be made