Results of a mechanistic model estimating methane in relation to methane emissions measured in dairy cows

This investigation determines the accuracy of estimation of methanogenesis by a dynamic mechanistic model with real data determined in a respiration trial, where cows were fed a wide range of different carbohydrates included in the concentrates. The model was able to predict ECM (Energy corrected milk) very well, while the NDF digestibility of fibrous feed was less well predicted. Methane emissions were predicted quite well, with the exception of one diet containing wheat. The mechanistic model is therefore a helpful tool to estimate methanogenesis based on chemical analysis and dry matter intake, but the prediction can still be improved.

Investigating the influence of extracellular matrix and glycolytic metabolism on muscle stem cell migration on their native fibre environment

The composition of the extracellular matrix (ECM) of skeletal muscle fibres is a unique environment that supports the regenerative capacity of satellite cells; the resident stem cell population. The impact of environment has great bearing on key properties permitting satellite cells to carry out tissue repair. In this study, we have investigated the influence of the ECM and glycolytic metabolism on satellite cell emergence and migration- two early processes required for muscle repair. Our results show that both influence the rate at which satellite cells emerge from the sub-basal lamina position and their rate of migration. These studies highlight the necessity of performing analysis of satellite behaviour on their native substrate and will inform on the production of artificial scaffolds intended for medical uses.

Ecto- and arbuscular mycorrhizal symbiosis can induce tolerance to toxic pulses of phosphorus in jarrah (Eucalyptus marginata) seedlings

In common with many plants native to low P soils, jarrah (Eucalyptus marginata) develops toxicity symptoms upon exposure to elevated phosphorus (P). Jarrah plants can establish arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) associations, along with a non-colonizing symbiosis described recently. AM colonization is known to influence the pattern of expression of genes required for P uptake of host plants and our aim was to investigate this phenomenon in relation to P sensitivity. Therefore, we examined the effect on hosts of the presence of AM and ECM fungi in combination with toxic pulses of P and assessed possible correlations between the induced tolerance and the shoot P concentration. The P transport dynamics of AM (Rhizophagus irregularis and Scutellospora calospora), ECM (Scleroderma sp.), non-colonizing symbiosis (Austroboletus occidentalis), dual mycorrhizal (R. irregularis and Scleroderma sp.), and non-mycorrhizal (NM) seedlings were monitored following two pulses of P. The ECM and A. occidentalis associations significantly enhanced the shoot P content of jarrah plants growing under P-deficient conditions. In addition, S. calospora, A. occidentalis, and Scleroderma sp. all stimulated plant growth significantly. All inoculated plants had significantly lower phytotoxicity symptoms compared to NM controls 7 days after addition of an elevated P dose (30 mg P kg−1 soil). Following exposure to toxicity-inducing levels of P, the shoot P concentration was significantly lower in R. irregularis-inoculated and dually inoculated plants compared to NM controls. Although all inoculated plants had reduced toxicity symptoms and there was a positive linear relationship between rank and shoot P concentration, the protective effect was not necessarily explained by the type of fungal association or the extent of mycorrhizal colonization.

Dual mycorrhizal associations of jarrah (Eucalyptus marginata) in a nurse-pot system

Jarrah (Eucalyptus marginata Donn ex Sm.) plants, like many other eucalypts, can form symbiotic associations with both arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) fungi. To study this tripartite relationship we developed a novel nurse-pot system to allow us to investigate the extent and temporal colonisation dynamics of jarrah by two AM species (Rhizophagus irregularis (Błaszk., Wubet, Renker & Buscot) C. Walker & A. Schüßler comb. nov. and Scutellospora calospora Nicol. & Gerd.) and two putative ECM species (Austroboletus occidentalis Watling & N.M. Greg. and Scleroderma sp.) and their potential effects on jarrah growth and nutrition. Our nurse-pot system, using jarrah as both the nurse plant and test plant, was developed to establish extraradical hyphal networks of both AM and ECM fungi that act as single or dual inoculum for test plants. Mycorrhizal colonisation was described and quantified, and growth and nutritional effects measured and analysed. Mycorrhizal colonisation increased with time for the test seedlings exposed to hyphae networks from S. calospora and Scleroderma sp. The nurse-pot system was effective at initiating colonisation of functioning AM or (putative) ECM systems separately but the ECM symbiosis was inhibited where a dual AM + ECM inoculum (R. irregularis and Scleroderma sp.) was present. The presence of S. calospora, A. occidentalis and Scleroderma sp. individually significantly increased the shoot biomass of seedlings compared with non-mycorrhizal controls. The two AM isolates had different physiological effects on jarrah plants. S. calospora improved growth and micronutrient uptake of jarrah seedlings whereas no positive response was observed with R. irregularis. In addition, as an interesting observation, the non-responsive AM fungus R. irregularis suppressed the ECM symbiosis in dually inoculated plants where ECM structures, positive growth response and nutritional effects were absent. When inoculated individually, ECM isolates dominated the growth response and uptake of P and other nutrients in this dual symbiotic plant. Despite the positive growth response in the A. occidentalis treatment, ECM structures were not observed in either nurse or test seedlings. From the effects of A. occidentalis on jarrah we hypothesise that this fungus forms a functional mycorrhizal-type partnership even without forming archetypal structures in and on the root

Regulation of cell migration in cancer: investigation into the regulation of cancer cell blebbing in the extracellular matrix

Cell migration is a highly coordinated process and any aberration in the regulatory mechanisms could result in pathological conditions such as cancer. The ability of cancer cells to disseminate to distant sites within the body has made it difficult to treat. Cancer cells also exhibit plasticity that makes them able to interconvert from an elongated, mesenchymal morphology to an amoeboid blebbing form under different physiological conditions. Blebs are spherical membrane protrusions formed by actomyosin-mediated contractility of cortical actin resulting in increased hydrostatic pressure and subsequent detachment of the membrane from the cortex. Tumour cells use blebbing as an alternative mode of migration by squeezing through preexisting gaps in the ECM, and bleb formation is believed to be mediated by the Rho-ROCK signaling pathway. However, the involvement of transmembrane water and ion channels in cell blebbing has not been examined. In the present study, the role of the transmembrane water channels, aquaporins, transmembrane ion transporters and lipid signaling enzymes in the regulation of blebbing was investigated. Using 3D matrigel matrix as an in vitro model to mimic normal extracellular matrix, and a combination of confocal and time-lapse microscopy, it was found that AQP1 knockdown by siRNA ablated blebbing of HT1080 and ACHN cells, and overexpression of AQP1-GFP not only significantly increased bleb size with a corresponding decrease in bleb numbers, but also induced bleb formation in non-blebbing cell lines. Importantly, AQP1 overexpression reduces bleb lifespan due to faster bleb retraction. This novel finding of AQP1-facilitated bleb retraction requires the activity of the Na+/H+ pump as inhibition of the ion transporter, which was found localized to intracellular vesicles, blocked bleb retraction in both cell lines. This study also demonstrated that a differential regulation of cell blebbing by AQP isoforms exists as knockdown of AQP5 had no effect on bleb formation. Data from this study also demonstrates that the lipid signaling PLD2 signals through PA in the LPA-LPAR-Rho-ROCK axis to positively regulate bleb formation in both cell lines. Taken together, this work provides a novel role of AQP1 and Na+/H+ pump in regulation of cell blebbing, and this could be exploited in the development of new therapy to treat cancer.