Viability of a FRET dual binding technique to detect calpastatin

We have been investigating a fluorescence dual binding biosensor to detect calpastatin. Calpastatin is a protein found in meat and it is a regulator of meat tenderness. The ability to accurately predict the calpastatin concentration of beef with a biological sensor at the time of grading would lead to a more accurate assessment of the overall palatability of beef when it reaches the consumer. Meat can then be labeled as tender or tough, which would greatly enhance meat processors' ability to grade meat, allowing them to recover lost revenue. The biosensor technique utilized the chemical transduction principle of fluorescence resonance energy transfer (FRET). FRET requires the use of two fluorophores, termed a donor and acceptor. In this study, the donor fluorophore was conjugated to the protein, mu-calpain, while the acceptor fluorophore was conjugated to a monoclonal antibody. The results showed that in the presence of calpastatin, the labeled mu-calpain and antibody would bind to calpastatin, reducing the distance between the two proteins and eliciting a measurable change in fluorescence. The FRET dual binding technique was tested in heated and unheated meat extract, and a limit of detection for calpastatin was 120 ng/ml in diluted heated meat extract with no significant response in the unheated meat extract. Stable response times were achieved within 5 min. The proof-of-principle of utilizing a FRET dual binding technique to detect calpastatin in heated meat extract has been established.     

Highly syntenic regions in the genomes of soybean, <Emphasis Type="Italic">Medicago truncatula</Emphasis>, and <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis>

Background  

Recent genome sequencing enables mega-base scale comparisons between related genomes. Comparisons between animals, plants, fungi, and bacteria demonstrate extensive synteny tempered by rearrangements. Within the legume plant family, glimpses of synteny have also been observed. Characterizing syntenic relationships in legumes is important in transferring knowledge from model legumes to crops that are important sources of protein, fixed nitrogen, and health-promoting compounds.     

Fishing Farmers: Fishing, Livelihood Diversification and Poverty in Rural Laos

The relationship between fishing, livelihood diversification and poverty was investigated in the lower Mekong basin, in Laos, where fishing forms an important, but usually secondary part of rural livelihoods. Results from a household survey show that participation in fishing is common and positively associated with higher occupational diversity and more agricultural activities. This is likely due to the low opportunity costs associated with many forms of fishing and factors such as tradition, enjoyment of fishing, underutilised labour and low capital requirements. Alternative livelihoods within the rural setting are therefore unlikely to cause fishers to leave the fishery, but instead strengthen the livelihood portfolio as a supplementary activity. Fishing is not an activity only for the very poorest households, but is undertaken by all wealth groups. However, fishing forms a greater proportion of income, employment and food security for the poor and is important in households with poor quality farm land.     

The structure of the unliganded extracellular domain of the interleukin-6 signal transducer gp130 in solution

Interleukin-6 (IL-6) plays an important role in immune responses and signals via two different pathways. When IL-6 binds to its non-signalling membrane-bound receptor (IL-6R), a non-covalent dimer of the ubiquitous interleukin-6 signal transducer gp130 is recruited to initiate intracellular signalling cascades. This so-called classical signalling pathway is restricted to cells expressing the membrane-bound IL-6R, such as hepatocytes and certain leukocytes. In addition, an alternative trans-signalling pathway uses soluble forms of IL-6R (sIL-6R) in complex with IL-6 to activate cells expressing gp130, but not membrane-bound IL-6R. In both cases, a tetrameric or hexameric signalling complex consisting of two gp130 molecules and one or two molecules each of IL-6 and (s)IL-6R is formed. The structure of the hexameric complex of the ligand-binding domains of gp130 (D1-D3) with IL-6 and sIL-6R has been solved by X-ray crystallography as well as the full-length extracellular part of gp130 (D1-D6) as a monomer. Since gp130 exists as a preformed dimer on the cell surface, we used a sgp130Fc fusion protein - consisting of two extracellular gp130 regions (D1-D6) dimerised by an IgG1-Fc part - to study the structure of unliganded gp130 extracellular domains in solution by small-angle X-ray scattering (SAXS). The SAXS data indicated that sgp130Fc forms a rigid molecule in solution. The low resolution structural model reveals an elongated assembly with an Fc base and two gp130 arms, whereby the orientation of the ligand-binding domains D1-D3 with respect to the membrane-proximal domains D4-D6 differs from that in the crystallographic monomer. Functional implications of these findings are discussed.     

Nocturne for an unknown pollinator: first description of a night‐flowering orchid (Bulbophyllum nocturnum)

Bulbophyllum nocturnum , a species of section Epicrianthes from New Britain, is described and illustrated. It is the first known example of an orchid species in which the flowers open after dark and close in the morning. The poorly understood pollination biology of section Epicrianthes, a clade with highly unusual flowers, is discussed. Attention is drawn to the close resemblance between the petal appendages of some species and the fruiting bodies of certain Myxogastria. © 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2011, 167 , 344–350.     

Increased soil stable nitrogen isotopic ratio following phosphorus enrichment: historical patterns and tests of two hypotheses in a phosphorus-limited wetland

We used a P enrichment gradient in the Everglades to investigate patterns of the stable N isotopic ratio (δ¹⁵N) in peat profiles as an indicator of historic eutrophication of this wetland. We also tested two hypotheses to explain the effects of P on increased δ¹⁵N of organic matter including: (1) increased N mineralization/N loss, and (2) reduced isotopic discrimination during macrophyte N uptake. Spatial patterns of δ¹⁵N in surface litter and soil (0–10 cm) mimic those of the aboveground macrophytes (Typha domingensis Pers. and Cladium jamaicense Crantz). Peat profiles also show increased δ¹⁵N in the peat accumulated in areas near the historic P discharges since the early 1960s. The increased δ¹⁵N of bulk peat correlated well with both measured increases in soil total P and the historical beginning of nutrient discharges into this wetland. In 15-day bottle incubations of soil, added P had no effect on the δ¹⁵N of NH₄⁺ and significantly increased the δ¹⁵N of water-extractable organic N. Measurements of surface soils collected during a field mesocosm experiment also revealed no significant effect of P on δ¹⁵N even after 5 years of P addition. In contrast, δ¹⁵N of leaf and root tissues of hydroponically grown Typha and Cladium were shown to increase up to 12‰ when grown at elevated levels of P and fixed levels of N (as NH₄⁺). The magnitude of changes in δ¹⁵N resulting from altered discrimination during N uptake is significant compared with other mechanisms affecting plant δ¹⁵N, and suggests that this may be the dominant mechanism affecting δ¹⁵N of organic matter following P enrichment. The results of this study have implications for the interpretation of δ¹⁵N as an indicator of shifts in relative N limitation in wetland ecosystems, and also stress the importance of experimental validation in interpreting δ¹⁵N patterns.     

How do trees respond to species mixing in experimental compared to observational studies?

For decades, ecologists have investigated the effects of tree species diversity on tree productivity at different scales and with different approaches ranging from observational to experimental study designs. Using data from five European national forest inventories (16,773 plots), six tree species diversity experiments (584 plots), and six networks of comparative plots (169 plots), we tested whether tree species growth responses to species mixing are consistent and therefore transferrable between those different research approaches. Our results confirm the general positive effect of tree species mixing on species growth (16% on average) but we found no consistency in species‐specific responses to mixing between any of the three approaches, even after restricting comparisons to only those plots that shared similar mixtures compositions and forest types. These findings highlight the necessity to consider results from different research approaches when selecting species mixtures that should maximize positive forest biodiversity and functioning relationships.