Invasive clonal plant species have a greater root-foraging plasticity than non-invasive ones

Clonality is frequently positively correlated with plant invasiveness, but which aspects of clonality make some clonal species more invasive than others is not known. Due to their spreading growth form, clonal plants are likely to experience spatial heterogeneity in nutrient availability. Plasticity in allocation of biomass to clonal growth organs and roots may allow these plants to forage for high-nutrient patches. We investigated whether this foraging response is stronger in species that have become invasive than in species that have not. We used six confamilial pairs of native European clonal plant species differing in invasion success in the USA. We grew all species in large pots under homogeneous or heterogeneous nutrient conditions in a greenhouse, and compared their nutrient-foraging response and performance. Neither invasive nor non-invasive species showed significant foraging responses to heterogeneity in clonal growth organ biomass or in aboveground biomass of clonal offspring. Invasive species had, however, a greater positive foraging response in terms of root and belowground biomass than non-invasive species. Invasive species also produced more total biomass. Our results suggest that the ability for strong root foraging is among the characteristics promoting invasiveness in clonal plants.

Long-term evaluation of myoblast seeded patches implanted on infarcted rat hearts

Cell transplantation presents great potential for treatment of patients with severe heart failure. However, its clinical application was revealed to be more challenging than initially expected in experimental studies. Further investigations need to be undertaken to define the optimal treatment conditions. We previously reported on the epicardial implantation of a bio-engineered construct of skeletal myoblast-seeded polyurethane and its preventive effect on progression toward heart failure. In the present study, we present a long-term evaluation of this functional outcome. Left anterior descending coronary ligation was performed in female Lewis rats. Two weeks later, animals were treated with either epicardial implantation of biograft, acellular scaffold, sham operation, or direct intramyocardial skeletal myoblast injection. Functional assessments were performed with serial echocardiographies every 3 months and end point left ventricle pressure was assessed. Hearts were then harvested for histological examinations. Myocardial infarction induced a slow and progressive reduction in fractional shortening after 3 months. Progression toward heart failure was significantly prevented for up to 6 months after injection of myoblasts and for up to 9 months following biograft implantation. Nevertheless, this effect vanished after 12 months, with immunohistological examinations revealing an absence of the transplanted myoblasts within the scaffold. We demonstrated that tissue therapy is superior to cell therapy for stabilization of heart function. However, beneficial effects are transient.

Patches of Bare Ground as a Staple Commodity for Declining Ground-Foraging Insectivorous Farmland Birds

Conceived to combat widescale biodiversity erosion in farmland, agri-environment schemes have largely failed to deliver their promises despite massive financial support. While several common species have shown to react positively to existing measures, rare species have continued to decline in most European countries. Of particular concern is the status of insectivorous farmland birds that forage on the ground. We modelled the foraging habitat preferences of four declining insectivorous bird species (hoopoe, wryneck, woodlark, common redstart) inhabiting fruit tree plantations, orchards and vineyards. All species preferred foraging in habitat mosaics consisting of patches of grass and bare ground, with an optimal, species-specific bare ground coverage of 30–70% at the foraging patch scale. In the study areas, birds thrived in intensively cultivated farmland where such ground vegetation mosaics existed. Not promoted by conventional agri-environment schemes until now, patches of bare ground should be implemented throughout grassland in order to prevent further decline of insectivorous farmland birds.

Effects of nutrient restriction on mammary cell turnover and mammary gland remodeling in lactating dairy cows

The aim of this study was to investigate the effects of a severe nutrient restriction on mammary tissue morphology and remodeling, mammary epithelial cell (MEC) turnover and activity, and hormonal status in lactating dairy cows. We used 16 Holstein x Normande crossbred dairy cows, divided into 2 groups submitted to different feeding levels (basal and restricted) from 2 wk before calving to wk 11 postpartum. Restricted-diet cows had lower 11-wk average daily milk yield from calving to slaughter than did basal-diet cows (20.5 vs. 33.5 kg/d). Feed restriction decreased milk fat, protein, and lactose yields. Restriction also led to lower plasma insulin-like growth factor 1 and higher growth hormone concentrations. Restricted-diet cows had lighter mammary glands than did basal-diet cows. The total amount of DNA in the mammary gland and the size of the mammary acini were smaller in the restricted-diet group. Feed restriction had no significant effect on MEC proliferation at the time of slaughter but led to a higher level of apoptosis in the mammary gland. Gelatin zymography highlighted remodeling of the mammary extracellular matrix in restricted-diet cows. Udders from restricted-diet cows showed lower transcript expression of alpha-lactalbumin and kappa-casein. In conclusion, nutrient restriction resulted in lower milk yield in lactating dairy cows, partly due to modulation of MEC activity and a lower number of mammary cells. An association was found between feed restriction-induced changes in the growth hormone-insulin-like growth factor-1 axis and mammary epithelial cell dynamics.

IFPA Meeting 2011 workshop report I: Placenta: Predicting future health; roles of lipids in the growth and development of feto-placental unit; placental nutrient sensing; placental research to solve clinical problems--a translational approach

Workshops are an important part of the IFPA annual meeting as they allow for discussion of specialized topics. At IFPA meeting 2011 there were twelve themed workshops, four of which are summarized in this report. These workshops related to both basic science and clinical research into placental growth and nutrient sensing and were divided into 1) placenta: predicting future health; 2) roles of lipids in the growth and development of feto-placental unit; 3) placental nutrient sensing; 4) placental research to solve clinical problems: a translational approach.

Preference of dairy cows for ryegrass, white clover and red clover, and its effects on nutrient supply and milk quality

Two experiments were conducted with 30 dairy cows each, to study the preference for fresh (Experiment 1) and ensiled (Experiment 2) ryegrass, white and red clover. Both experiments consisted of three choice diets with white or red clover or both, offered with ryegrass, and two diets with ryegrass mixed with white or red clover (40% clover). Cows consumed diets with 37.7% fresh white and 45.9% red clover, and no preference was observed when the cows were offered all three forages. By contrast, cows preferred white and red clover silage (73.0 and 69.2%, respectively) over ryegrass silage (of lower nutritive quality). When offered three forages, cows preferred white (59.8%) over red clover (17.5%) and ryegrass (22.7%). Choice diets resulted in diets similar (fresh forages) or higher in nutrient content and digestibility (silages). Treatments did not affect feed intake and performance. Choices compared to mixed diets with red clover silage were preferable regarding the fatty acid composition of the milk fat. Obviously, only large differences in nutrient and energy concentration facilitate preferences for clovers over ryegrass, which could, depending on clover type, be beneficial in terms of the milk's fatty acid composition.

Nutrient-responsive mTOR signalling grows on Sterile ground

The control of cell growth, that is cell size, is largely controlled by mTOR (the mammalian target of rapamycin), a large serine/threonine protein kinase that regulates ribosome biogenesis and protein translation. mTOR activity is regulated both by the availability of growth factors, such as insulin/IGF-1 (insulin-like growth factor 1), and by nutrients, notably the supply of certain key amino acids. The last few years have seen a remarkable increase in our understanding of the canonical, growth factor-regulated pathway for mTOR activation, which is mediated by the class I PI3Ks (phosphoinositide 3-kinases), PKB (protein kinase B), TSC1/2 (the tuberous sclerosis complex) and the small GTPase, Rheb. However, the nutrient-responsive input into mTOR is important in its own right and is also required for maximal activation of mTOR signalling by growth factors. Despite this, the details of the nutrient-responsive signalling pathway(s) controlling mTOR have remained elusive, although recent studies have suggested a role for the class III PI3K hVps34. In this issue of the Biochemical Journal, Findlay et al. demonstrate that the protein kinase MAP4K3 [mitogen-activated protein kinase kinase kinase kinase-3, a Ste20 family protein kinase also known as GLK (germinal centre-like kinase)] is a new component of the nutrient-responsive pathway. MAP4K3 activity is stimulated by administration of amino acids, but not growth factors, and this is insensitive to rapamycin, most likely placing MAP4K3 upstream of mTOR. Indeed, MAP4K3 is required for phosphorylation of known mTOR targets such as S6K1 (S6 kinase 1), and overexpression of MAP4K3 promotes the rapamycin-sensitive phosphorylation of these same targets. Finally, knockdown of MAP4K3 levels causes a decrease in cell size. The results suggest that MAP4K3 is a new component in the nutrient-responsive pathway for mTOR activation and reveal a completely new function for MAP4K3 in promoting cell growth. Given that mTOR activity is frequently deregulated in cancer, there is much interest in new strategies for inhibition of this pathway. In this context, MAP4K3 looks like an attractive drug target since inhibitors of this enzyme should switch off mTOR, thereby inhibiting cell growth and proliferation, and promoting apoptosis.

Buttress form of the central African rain forest tree Microberlinia bisulcata, and its possible role in nutrient acquisition

Buttressing is a trait special to tropical trees but explanations for its occurrence remain inconclusive. The two main hypotheses are that they provide structural support and/or promote nutrient acquisition. Studies of the first are common but the second has received much less attention. Architectural measurements were made on adult and juvenile trees of the ectomycorrhizal species Microberlinia bisulcata, in Korup (Cameroon). Buttressing on this species is highly distinctive with strong lateral extension of surface roots of the juveniles leading to a mature buttress system of a shallow spreading form on adults. This contrasts with more vertical buttresses, closer to the stem, found on many other tropical tree species. No clear relationship between main buttress and large branch distribution was found. Whilst this does not argue against the essential structural role of buttresses for these very large tropical trees, the form on M. bisulcata does suggest a likely second role, that of aiding nutrient acquisition. At the Korup site, with its deep sandy soils of very low phosphorus status, and where most nutrient cycling takes place in a thin surface layer of fine roots and mycorrhizas, it appears that buttress form could develop from soil-surface root exploration for nutrients by juvenile trees. It may accordingly allow M. bisulcata to attain the higher greater competitive ability, faster growth rate, and maximum tree size that it does compared with other co-occurring tree species. For sites across the tropics in general, the degree of shallowness and spatial extension of buttresses of the dominant species is hypothesized to increase with decreasing nutrient availability.