More than one way of being a moa: differences in leg bone robustness map divergent evolutionary trajectories in Dinornithidae and Emeidae (Dinornithiformes).

The extinct moa of New Zealand included three families (Megalapterygidae; Dinornithidae; Emeidae) of flightless palaeognath bird, ranging in mass from 200 kg. They are perceived to have evolved extremely robust leg bones, yet current estimates of body mass have very wide confidence intervals. Without reliable estimators of mass, the extent to which dinornithid and emeid hindlimbs were more robust than modern species remains unclear. Using the convex hull volumetric-based method on CT-scanned skeletons, we estimate the mass of a female Dinornis robustus (Dinornithidae) at 196 kg (range 155-245 kg) and of a female Pachyornis australis (Emeidae) as 50 kg (range 33-68 kg). Finite element analysis of CT-scanned femora and tibiotarsi of two moa and six species of modern palaeognath showed that P. australis experienced the lowest values for stress under all loading conditions, confirming it to be highly robust. In contrast, stress values in the femur of D. robustus were similar to those of modern flightless birds, whereas the tibiotarsus experienced the highest level of stress of any palaeognath. We consider that these two families of Dinornithiformes diverged in their biomechanical responses to selection for robustness and mobility, and exaggerated hindlimb strength was not the only successful evolutionary pathway

Case Reports1. A Late Presentation of Loeys-Dietz Syndrome: Beware of TGFβ Receptor Mutations in Benign Joint Hypermobility

Background: Thoracic aortic aneurysms (TAA) and dissections are not uncommon causes of sudden death in young adults. Loeys-Dietz syndrome (LDS) is a rare, recently described, autosomal dominant, connective tissue disease characterized by aggressive arterial aneurysms, resulting from mutations in the transforming growth factor beta (TGFβ) receptor genes TGFBR1 and TGFBR2. Mean age at death is 26.1 years, most often due to aortic dissection. We report an unusually late presentation of LDS, diagnosed following elective surgery in a female with a long history of joint hypermobility. Methods: A 51-year-old Caucasian lady complained of chest pain and headache following a dural leak from spinal anaesthesia for an elective ankle arthroscopy. CT scan and echocardiography demonstrated a dilated aortic root and significant aortic regurgitation. MRA demonstrated aortic tortuosity, an infrarenal aortic aneurysm and aneurysms in the left renal and right internal mammary arteries. She underwent aortic root repair and aortic valve replacement. She had a background of long-standing joint pains secondary to hypermobility, easy bruising, unusual fracture susceptibility and mild bronchiectasis. She had one healthy child age 32, after which she suffered a uterine prolapse. Examination revealed mild Marfanoid features. Uvula, skin and ophthalmological examination was normal. Results: Fibrillin-1 testing for Marfan syndrome (MFS) was negative. Detection of a c.1270G > C (p.Gly424Arg) TGFBR2 mutation confirmed the diagnosis of LDS. Losartan was started for vascular protection. Conclusions: LDS is a severe inherited vasculopathy that usually presents in childhood. It is characterized by aortic root dilatation and ascending aneurysms. There is a higher risk of aortic dissection compared with MFS. Clinical features overlap with MFS and Ehlers Danlos syndrome Type IV, but differentiating dysmorphogenic features include ocular hypertelorism, bifid uvula and cleft palate. Echocardiography and MRA or CT scanning from head to pelvis is recommended to establish the extent of vascular involvement. Management involves early surgical intervention, including early valve-sparing aortic root replacement, genetic counselling and close monitoring in pregnancy. Despite being caused by loss of function mutations in either TGFβ receptor, paradoxical activation of TGFβ signalling is seen, suggesting that TGFβ antagonism may confer disease modifying effects similar to those observed in MFS. TGFβ antagonism can be achieved with angiotensin antagonists, such as Losartan, which is able to delay aortic aneurysm development in preclinical models and in patients with MFS. Our case emphasizes the importance of timely recognition of vasculopathy syndromes in patients with hypermobility and the need for early surgical intervention. It also highlights their heterogeneity and the potential for late presentation. Disclosures: The authors have declared no conflicts of interes

Interdisciplinary dialogue for sustainable systems

Why do ‘birds of a feather flock together?’ Is it possible for individuals and groups from different philosophical backgrounds and disciplines to agree on ways to solve problems? Arguments abound about the importance and necessity of involving all stakeholders in decision making. Some say that interdisciplinary groups are essential to such a process to avoid the narrow focus of uni-disciplinary groups, yet others argue that competition among disciplines may be more fruitful than co-operation. Most do agree that the way forward, to achieve more sustainable development so as to avoid past mistakes, is seen as requiring more debate from a broader stakeholder base, one that does not just involve ‘experts’. Why then does this so rarely happen satisfactorily? There are many blocks to the interdisciplinary approach at societal and policy levels. Even though, at different levels in our daily lives we interact with many different citizens. But, when it comes to professional decisions, we seem to feel more comfortable interacting with those of the same ‘feather’. Linking farming with the many levels of government and private sectors and other parts of the food chain system is a complex process. This paper reviews the dialogue between experts at an interdisciplinary workshop funded by the Organisation for Economic Co-operation and Development (OECD) in Ballina, Australia. The Pressure State Response model formed the basis of the dialogue. Within the example of a biophysical context of diffuse source pollution from agriculture, 50 experts from the social, environmental and economic disciplines, therefore representing the sustainability model, discussed how to overcome the barriers to effectively, aligning policies and acknowledging and working with the vastly different world views of the participants

The relationship between convex hull volume and literature values for mass in extant ratites.

<p>LR, linear regression; SMA, standardized major axis regression; MA, major axis regression; LRO, linear regression forced through the origin.</p

Loading regimes for finite element analysis of <i>Dinornis</i> femur

<p>(<i>a</i>) Medial view of femoral head, yellow arrows originate from the nodes to which force is applied. The direction of force is aligned parallel to the long axis of the bone, i.e. loading in compression. (<i>b</i>) Dorsal view of the proximal femoral epiphysis. Orange dot represents constrained control point, and is surrounded by 10 yellow dots representing the nodes to which torsion is applied via the kinematic coupling. (<i>c</i>) Ventral view of the distal femoral condyles. Orange squares represent nodes subject to encastre boundary conditions.</p

Finite element analysis specimen list and sources of body mass.

<p><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0082668#pone-0082668-t001" target="_blank">Table 1</a>. For <i>Dromaius novaehollandiae</i> and <i>Rhea americana</i>, body mass was recorded directly from the carcass. <i>F</i>, total force applied to the finite element model in Newtons. Body mass estimated for the finite element analysis specimens using the same species-specific regressions of known body mass against a linear metric from the hind limb, as in </p

Finite element analysis results.

<p>Combined compression-bending results for the femur (a) and tibiotarsus (b). Values represent maximum von Mises stress (Pa) recorded at the midshaft of the bone. Pink and blue shaded areas represent the range of stress values estimated by finite element analysis when incorporating maximum and minimum values for body mass in <i>D. robustus</i> and <i>P. australis</i> respectively. Area enclosed by dark blue box is expanded in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0082668#pone-0082668-g006" target="_blank">Figure 6</a>.</p

Convex hull specimen list and sources of body mass.

<p><i>M</i>_b) was estimated for the convex hull individuals by first generating species-specific least squares regressions of known body mass against a linear metric from the hind limb as reported in the literature. Body mass (</p><p><i>Dromaius novaehollandiae</i> femoral length against body mass derived from carcasses of known body mass from the University of Manchester. Regression equation of </p><p><i>Rhea spp.</i> tibiotarsal length against body mass generated from previously published raw data and one carcass from the University of Manchester. Regression equation of </p

Moa convex hull volumes and body segment volumes.

<p> Trunk values include minimum and maximum volumes defined by shifting the sternum dorsoventrally. Segment values consist of the sum total of left and right elements.</p

Moa convex hulls

<p>(<i>a</i>) <i>Dinornis robustus</i> (S.34088/89) reconstruction of convex hulls; (<i>b</i>) <i>Pachyornis australis</i> (S.27896) (<i>a</i> and <i>b</i> are to the same scale); (<i>c</i>) and (<i>d</i>) show different positions of the sternum in <i>D. robustus</i>.</p