A Protocol for Prolonged Surgical Anaesthesia with Recovery in Fire Salamanders Using Tricaine Mesylate (MS-222): A Case Series.

The objective of this study was to describe prolonged surgical anaesthesia and recovery in fire salamanders (Salamandra salamandra) using tricaine methanesulfonate (MS-222). A total of 14 salamanders were anaesthetised for electromyography wire implantation. Sodium bicarbonate buffered solutions (0.5-4 g l-1) of MS-222 were prepared (adjusted to pH 7.0). Anaesthesia was induced by partial immersion in pre-oxygenated 3 g l-1 solution for 20 min. Buprenorphine (0.5 mg kg-1) was administered subcutaneously. During microsurgery, heart rate (HR), solution pH and temperature were recorded. Reflectance pulse oximeter (SpO2) (Masimo Rad-57) was recorded in two salamanders. Anaesthetic plane and MS-222 pH stability (pH 7.6) were maintained by renewing administration of oxygenated MS-222 solution (0.5-3 g l-1) onto swabs that partially covered the body. Recovery started at the end of surgery (MS-222 0 g l-1). Postoperatively, salamanders were given oral meloxicam (0.2 mg kg-1). Mean time for loss of righting reflex during induction was 13.7 ± 2.2 min. Duration of anaesthesia and time to recovery were 111 ± 24.2 and 31 ± 10.3 min, respectively. Due to complications, two salamanders did not recover. Baseline HR was 67.4 ± 34.5 beats/min, and it decreased significantly until recovery (p ≤ 0.0001). In two salamanders, baseline SpO2 was 85.5% ± 14.5, SpO2 during surgery was 61% ± 6.4, improving to 80.5% ± 2.1 on recovery.In conclusion, prolonged recovery anaesthesia is achievable with MS-222 dilutions in salamander. Reflectance SpO2 could prove valuable during immersion anaesthesia.

AutoBend: An Automated Approach for Estimating Intervertebral Joint Function from Bone-Only Digital Models.

Deciphering the biological function of rare or extinct species is key to understanding evolutionary patterns across the tree of life. While soft tissues are vital determinants of joint function, they are rarely available for study. Therefore, extracting functional signals from skeletons, which are more widely available via museum collections, has become a priority for the field of comparative biomechanics. While most work has focused on the limb skeleton, the axial skeleton plays a critical role in body support, respiration, and locomotion, and is therefore of central importance for understanding broad-scale functional evolution. Here, we describe and experimentally validate AutoBend, an automated approach to estimating intervertebral joint function from bony vertebral columns. AutoBend calculates osteological range of motion (oROM) by automatically manipulating digitally articulated vertebrae while incorporating multiple constraints on motion, including both bony intersection and the role of soft tissues by restricting excessive strain in both centrum and zygapophyseal articulations. Using AutoBend and biomechanical data from cadaveric experiments on cats and tegus, we validate important modeling parameters required for oROM estimation, including the degree of zygapophyseal disarticulation, and the location of the center of rotation. Based on our validation, we apply a model with the center of rotation located within the vertebral disk, no joint translation, around 50% strain permitted in both zygapophyses and disks, and a small amount of vertebral intersection permitted. Our approach successfully reconstructs magnitudes and craniocaudal patterns of motion obtained from ex vivo experiments, supporting its potential utility. It also performs better than more typical methods that rely solely on bony intersection, emphasizing the importance of accounting for soft tissues. We estimated the sensitivity of the analyses to vertebral model construction by varying joint spacing, degree of overlap, and the impact of landmark placement. The effect of these factors was small relative to biological variation craniocaudally and between bending directions. We also present a new approach for estimating joint stiffness directly from oROM and morphometric measurements that can successfully reconstruct the craniocaudal patterns, but not magnitudes, derived from experimental data. Together, this work represents a significant step forward for understanding vertebral function in difficult-to-study (e.g., rare or extinct) species, paving the way for a broader understanding of patterns of functional evolution in the axial skeleton.

Resumo [Portuguese] Decifrar a função biológica de espécies raras ou extintas é fundamental para se compreender os padrões evolutivos na árvore da vida. Embora os tecidos moles sejam determinantes vitais das funções articulares, estes raramente estão disponíveis para estudo. Portanto, extrair dados funcionais provenientes de esqueletos, que são mais amplamente disponíveis por meio de coleções de museus, tornou-se uma prioridade para o campo da biomecânica comparada. Embora a maioria dos trabalhos biomecânicos tenham focado no esqueleto apendicular, o esqueleto axial também desempenha um papel crítico para o suporte corporal, respiração e locomoção e, portanto, é de importância central para a compreensão da evolução funcional em escalas amplas. Nesse trabalho, nós descrevemos e validamos experimentalmente o AutoBend, uma abordagem automatizada para estimar a função da articulação intervertebral de colunas vertebrais ósseas. O AutoBend calcula a amplitude do movimento osteológico (AMO) manipulando automaticamente as vértebras reconstruídas digitalmente e incorporando várias restrições de movimento, incluindo restrições das interseções ósseas e o papel de restrição dos tecidos moles na tensão excessiva sobre as articulações dos centros vertebrais e zigapofisárias. Usando AutoBend e dados biomecânicos de experimentos cadavéricos em gatos e lagartos tegus, validamos parâmetros de modelagem importantes e necessários para as estimativa do AMO, incluindo o grau de desarticulação zigapofisária e a localização do centro de rotação. Com base nessa validação, aplicamos um modelo com o centro de rotação localizado dentro do disco vertebral, sem translação articular, com cerca de 50% de tensão permitida nas zigapófises e discos vertebrais, além de uma pequena quantidade de intersecção vertebral permitida. Nossa abordagem reconstrói com sucesso magnitudes e padrões de movimento craniocaudais obtidos a partir de experimentos ex vivo, corroborando a sua potencial utilidade. Esse modelo também tem um desempenho melhor do que os métodos mais típicos que dependem apenas das interseções ósseas, enfatizando a importância de se levar em conta o papel dos tecidos moles. Estimamos a sensibilidade das análises à reconstrução do modelo vertebral, variando o espaçamento entre articulações, o grau de sobreposição e o impacto da localização dos pontos de referência. O efeito desses fatores foi pequeno em relação à variação biológica craniocaudal e entre as direções de flexão. Apresentamos aqui também uma nova abordagem para se estimar a rigidez articular diretamente à partir do AMO e medidas morfométricas que podem reconstruir com sucesso os padrões craniocaudais (embora não as magnitudes) derivados de dados experimentais. Este trabalho representa um passo significativo para a melhor compreensão da função vertebral em espécies difíceis de estudar (por exemplo, raras ou extintas), abrindo caminho para uma compreensão mais ampla dos padrões de evolução funcional no esqueleto axial.

Resumen [Spanish] Descifrar la función biológica de especies raras o extintas es fundamental para comprender los patrones evolutivos del árbol de la vida. Aunque los tejidos blandos son determinantes vitales de la función articular, raramente están disponibles para su estudio. Por lo tanto, la extracción de datos funcionales de esqueletos, que están más comumente disponibles a través de colecciones de museos, se ha convertido en una prioridad para el campo de la biomecánica comparada. Aunque la mayor parte del trabajo biomecánico se ha centrado en el esqueleto apendicular, el esqueleto axial también desempeña un papel fundamental para el soporte del cuerpo, la respiración y la locomoción y, por lo tanto, es de vital importancia para comprender la evolución funcional a gran escala. En este trabajo, describimos y validamos experimentalmente AutoBend, una herramienta automatizada para estimar la función de la articulación intervertebral en las columnas vertebrales óseas. AutoBend calcula el rango de movimiento osteológico (RMOo) manipulando automáticamente las vértebras reconstruidas digitalmente e incorporando varias restricciones de movimiento, incluidas las restricciones de intersección ósea y el papel de la restricción de tejidos blandos en la tensión excesiva sobre las articulaciones cigapofisarias y centros vertebrales. Utilizando AutoBend y datos biomecánicos de experimentos cadavéricos en gatos y lagartos tegus, validamos importantes parámetros de modelado necesarios para estimar el RMOo, incluido el grado de desarticulación cigapofisaria y la ubicación del centro de rotación. Con base en esta validación, aplicamos un modelo con el centro de rotación ubicado dentro del disco vertebral, sin traslación articular, con 50% de tensión permisible en la cigapófisis y los discos vertebrales, además de una pequeña cantidad de intersección vertebral permitida. Nuestra herramienta reconstruye con éxito magnitudes craneocaudales y patrones de movimiento obtenidos de experimentos ex vivo, corroborando su potencial utilidad. Este modelo también funciona mejor que los métodos más típicos que se basan solo en las intersecciones óseas, enfatizando la importancia de tener en cuenta el papel de los tejidos blandos. Estimamos la sensibilidad de los análisis a la reconstrucción del modelo vertebral, variando el espaciamiento entre articulaciones, el grado de superposición y el impacto de la ubicación de los puntos de referencia. El efecto de estos factores fue pequeño en relación a la variación biológica craneocaudal y entre las direcciones de flexión. También presentamos aquí un nuevo enfoque para estimar la rigidez articular directamente de la RMOo y mediciones morfométricas que pueden reconstruir con éxito los patrones craneocaudales (aunque no las magnitudes) derivados de datos experimentales. Este trabajo representa un paso significativo hacia una mejor comprensión de la función vertebral en especies difíciles de estudiar (por ejemplo, raras o extintas), allanando el camino para una comprensión más amplia de los patrones de evolución funcional en el esqueleto axial.

Evolution of forelimb musculoskeletal function across the fish-to-tetrapod transition.

One of the most intriguing questions in vertebrate evolution is how tetrapods gained the ability to walk on land. Although many hypotheses have been proposed, few have been rigorously tested using the fossil record. Here, we build three-dimensional musculoskeletal models of the pectoral appendage in Eusthenopteron, Acanthostega, and Pederpes and quantitatively examine changes in forelimb function across the fin-to-limb transition. Through comparison with extant fishes and tetrapods, we show that early tetrapods share a suite of characters including restricted mobility in humerus long-axis rotation, increased muscular leverage for humeral retraction, but not depression/adduction, and increased mobility in elbow flexion-extension. We infer that the earliest steps in tetrapod forelimb evolution were related to limb-substrate interactions, whereas specializations for weight support appeared later. Together, these results suggest that competing selective pressures for aquatic and terrestrial environments produced a unique, ancestral "early tetrapod" forelimb locomotor mode unlike that of any extant animal.

Patterns of Limb and Epaxial Muscle Activity During Walking in the Fire Salamander, Salamandra salamandra.

Salamanders and newts (urodeles) are often used as a model system to elucidate the evolution of tetrapod locomotion. Studies range from detailed descriptions of musculoskeletal anatomy and segment kinematics, to bone loading mechanics and inferring central pattern generators. A further area of interest has been in vivo muscle activity patterns, measured through electromyography (EMG). However, most prior EMG work has primarily focused on muscles of the forelimb or hindlimb in specific species or the axial system in others. Here we present data on forelimb, hindlimb, and epaxial muscle activity patterns in one species, Salamandra salamandra, during steady state walking. The data are calibrated to limb stride cycle events (stance phase, swing phase), allowing direct comparisons to homologous muscle activation patterns recorded for other walking tetrapods (e.g., lizards, alligators, turtles, mammals). Results demonstrate that Salamandra has similar walking kinematics and muscle activity patterns to other urodele species, but that interspecies variation does exist. In the forelimb, both the m. dorsalis scapulae and m. latissimus dorsi are active for 80% of the forelimb swing phase, while the m. anconaeus humeralis lateralis is active at the swing-stance phase transition and continues through 86% of the stance phase. In the hindlimb, both the m. puboischiofemoralis internus and m. extensor iliotibialis anterior are active for 30% of the hindlimb swing phase, while the m. caudofemoralis is active 65% through the swing phase and remains active for most of the stance phase. With respect to the axial system, both the anterior and posterior m. dorsalis trunci display two activation bursts, a pattern consistent with stabilization and rotation of the pectoral and pelvic girdles. In support of previous assertions, comparison of Salamandra muscle activity timings to other walking tetrapods revealed broad-scale similarities, potentially indicating conservation of some aspects of neuromuscular function across tetrapods. Our data provide the foundation for building and testing dynamic simulations of fire salamander locomotor biomechanics to better understand musculoskeletal function. They could also be applied to future musculoskeletal simulations of extinct species to explore the evolution of tetrapod locomotion across deep-time.

Padrones de actividad muscular epaxial y apendicular durante la cursorialidad de la salamandra-de-fuego, Salamandra salamandra Las salamandras y los tritones (urodelos) son utilizados con frecuencia como un sistema modelo para dilucidar la evolución de la locomoción en los tetrápodos. Los estudios previos varían de descripciones detalladas de la anatomía musculoesquelética y cinemática de los segmentos del cuerpo, a la mecánica de la capacidad de soporte de carga estructural ósea y la generación de padrones centrales. Otra área de interés ha sido los padrones de actividad muscular in vivo, medidos por electromiografía (EMG). Sin embargo, la mayoría de los trabajos anteriores con EMG se han centrado principalmente en los músculos de los miembros anteriores o posteriores en especies específicas o en el sistema axial de otras. En este trabajo, presentamos datos sobre los padrones de actividad muscular en los músculos de los miembros anteriores, posteriores y de la musculatura epaxial en una especie, Salamandra salamandra, durante la marcha continua. Los datos se calibran para los períodos del ciclo de caminar de los miembros (fase de soporte, fase de movimiento), lo que permite comparaciones directas con padrones de activación muscular homólogos registrados para otros tetrápodos cursoriales (por ejemplo, lagartos, caimanes, tortugas y mamíferos). Los resultados demuestran que Salamandra tiene padrones de cinemática cursorial y actividad muscular similares a otras especies de urodelos, pero con variación interespecífica. En los miembros anteriores, ambos los m. dorsalis scapulae y m. latissimus dorsi están activos en 80% de la fase de movimiento del miembro anterior, mientras que el m. anconaeus humeralis lateralis se activa en la transición de la fase de movimiento-soporte y permanece activo en 86% de la fase de soporte. En los miembros posteriores, ambos m. puboischiofemoralis internus y m. extensor iliotibialis anterior están activos en 30% de la fase de movimiento de los miembros posteriores, mientras que el m. caudofemoralis está activo durante el 65% de la fase de movimiento, permaneciendo activo durante la mayor parte de la fase de soporte. Con respecto al sistema axial, las porciones anterior y posterior del m. dorsalis trunci exhibe dos períodos de activación, un padrón consistente con la estabilización y rotación de la cintura pélvica y pectoral. Como sugirido anteriormente, la comparación de los tiempos de actividad muscular de Salamandra con otros tetrápodos cursoriales reveló similitudes en gran escala, lo que podría indicar la conservación de algunos aspectos de la función neuromuscular entre los tetrápodos. Nuestros datos proporcionan una base para la construcción y prueba de simulaciones dinámicas de la biomecánica locomotora de salamandras-de-fuego para comprender mejor las funciones musculoesqueléticas. Nuestros resultados también se pueden aplicar a futuras simulaciones musculoesqueléticas de especies extintas para explorar la evolución de la locomoción de tetrápodos en el tiempo profundo.

Padrões de atividade muscular epaxial e apendicular durante a cursorialidade da salamandra-de-fogo, Salamandra salamandra Salamandras e tritões (urodelos) são freqüentemente utilizados como um sistema modelo para elucidar a evolução da locomoção em tetrápodes. Estudos anteriores variam de descrições detalhadas da anatomia musculoesquelética e cinemática dos segmentos corporais, a mecânica da capacidade de carga estrutural óssea e geradora de padrões centrais. Uma outra área de interesse tem sido os padrões de atividade muscular in vivo, medidos por eletromiografia (EMG). No entanto, a maioria dos trabalhos anteriores de EMG concentrou-se principalmente nos músculos dos membros anteriores ou posteriores em espécies específicas ou no sistema axial de outras. Nesse trabalho, apresentamos dados sobre os padrões de atividade muscular nos membros anteriores, posteriores e musculatura epaxial em uma espécie, Salamandra salamandra, durante caminhada em modo contínuo. Os dados são calibrados para os períodos do ciclo de caminhada dos membros (fase de apoio, fase de movimento), permitindo comparações diretas com padrões de ativação muscular homólogos registrados para outros tetrápodes cursoriais (por exemplo, lagartos, jacarés, tartarugas e mamíferos). Os resultados demonstram que Salamandra possui padrões de cinemática cursorial e atividade muscular semelhantes à outras espécies de urodelos, mas com variação interespecífica. Nos membros anteriores, ambos os m. dorsalis scapulae e m. latissimus dorsi estão ativos em 80% da fase de movimento do membro anterior, enquanto o m. anconaeus humeralis lateralis é ativado na transição da fase de movimento-apoio e continua ativo em 86% da fase de apoio. Nos membros posteriores, ambos m. puboischiofemoralis internus e m. extensor iliotibialis anterior estão ativos em 30% da fase de movimento dos membros posteriores, enquanto o m. caudofemoralis está ativo por 65% da fase de movimento, permanecendo ativo na maior parte da fase de apoio. No que diz respeito ao sistema axial, as porções anterior e posterior do m. dorsalis trunci exibe dois períodos de ativação, um padrão consistente com a estabilização e rotação da cintura peitoral e pélvica. Como préviamente sugerido, a comparação dos tempos de atividade muscular de Salamandra com outros tetrápodes cursoriais revelou similaridades em larga escala, potencialmente indicando a conservação de alguns aspectos da função neuromuscular entre tetrápodes. Os nossos dados fornecem uma base para a construção e testagem de simulações dinâmicas da biomecânica locomotora de salamandras-de-fogo para se entender melhor as funções músculo-esqueléticas. Nossos resultados também podem ser aplicados a futuras simulações músculo-esqueléticas de espécies extintas para explorar a evolução da locomoção de tetrápodes no tempo profundo.

Fossils reveal the complex evolutionary history of the mammalian regionalized spine.

A unique characteristic of mammals is a vertebral column with anatomically distinct regions, but when and how this trait evolved remains unknown. We reconstructed vertebral regions and their morphological disparity in the extinct forerunners of mammals, the nonmammalian synapsids, to elucidate the evolution of mammalian axial differentiation. Mapping patterns of regionalization and disparity (heterogeneity) across amniotes reveals that both traits increased during synapsid evolution. However, the onset of regionalization predates increased heterogeneity. On the basis of inferred homology patterns, we propose a "pectoral-first" hypothesis for region acquisition, whereby evolutionary shifts in forelimb function in nonmammalian therapsids drove increasing vertebral modularity prior to differentiation of the vertebral column for specialized functions in mammals.

Axial allometry in a neutrally buoyant environment: effects of the terrestrial-aquatic transition on vertebral scaling.

Ecological diversification into new environments presents new mechanical challenges for locomotion. An extreme example of this is the transition from a terrestrial to an aquatic lifestyle. Here, we examine the implications of life in a neutrally buoyant environment on adaptations of the axial skeleton to evolutionary increases in body size. On land, mammals must use their thoracolumbar vertebral column for body support against gravity and thus exhibit increasing stabilization of the trunk as body size increases. Conversely, in water, the role of the axial skeleton in body support is reduced, and, in aquatic mammals, the vertebral column functions primarily in locomotion. Therefore, we hypothesize that the allometric stabilization associated with increasing body size in terrestrial mammals will be minimized in secondarily aquatic mammals. We test this by comparing the scaling exponent (slope) of vertebral measures from 57 terrestrial species (23 felids, 34 bovids) to 23 semi-aquatic species (pinnipeds), using phylogenetically corrected regressions. Terrestrial taxa meet predictions of allometric stabilization, with posterior vertebral column (lumbar region) shortening, increased vertebral height compared to width, and shorter, more disc-shaped centra. In contrast, pinniped vertebral proportions (e.g. length, width, height) scale with isometry, and in some cases, centra even become more spool-shaped with increasing size, suggesting increased flexibility. Our results demonstrate that evolution of a secondarily aquatic lifestyle has modified the mechanical constraints associated with evolutionary increases in body size, relative to terrestrial taxa.

Big cat, small cat: reconstructing body size evolution in living and extinct Felidae.

The evolution of body mass is a fundamental topic in evolutionary biology, because it is closely linked to manifold life history and ecological traits and is readily estimable for many extinct taxa. In this study, we examine patterns of body mass evolution in Felidae (Placentalia, Carnivora) to assess the effects of phylogeny, mode of evolution, and the relationship between body mass and prey choice in this charismatic mammalian clade. Our data set includes 39 extant and 26 extinct taxa, with published body mass data supplemented by estimates based on condylobasal length. These data were run through 'SURFACE' and 'bayou' to test for patterns of body mass evolution and convergence between taxa. Body masses of felids are significantly different among prey choice groupings (small, mixed and large). We find that body mass evolution in cats is strongly influenced by phylogeny, but different patterns emerged depending on inclusion of extinct taxa and assumptions about branch lengths. A single Ornstein-Uhlenbeck optimum best explains the distribution of body masses when first-occurrence data were used for the fossil taxa. However, when mean occurrence dates or last known occurrence dates were used, two selective optima for felid body mass were recovered in most analyses: a small optimum around 5 kg and a large one around 100 kg. Across living and extinct cats, we infer repeated evolutionary convergences towards both of these optima, but, likely due to biased extinction of large taxa, our results shift to supporting a Brownian motion model when only extant taxa are included in analyses.

Motivating factors and perceived barriers to participating in continuing professional development: a national survey of veterinary surgeons.

Although continuing professional development (CPD) is regarded as mandatory by the Royal College of Veterinary Surgeons, it is not yet a statutory requirement. To understand what motivates veterinary surgeons to engage in CPD and perceived barriers to participation, a national survey was administered to a sample of the profession. The study sought to report overall opinion and to compare the views of different groups in terms of decade of graduation, gender, employment status, area of employment and position in the workplace. The results of the study are encouraging in that recent graduates would like to engage in more CPD, compared with their predecessors, and are the most intrinsically and extrinsically motivated. However, significant barriers to participation exist, including personal barriers, a lack of workplace support and a lack of CPD activities at a suitable time, location or level. Part-time workers reported higher barriers than full-time workers. Although the majority (90 per cent) of respondents receive all or part of their CPD funding from employers, a significant proportion (41 per cent) are required to fund at least part of their CPD. First-opinion practitioners reported significantly less access to a professional library, which has implications for lifelong learning and the practice of evidence-based veterinary medicine.

Comparative axial morphology in pinnipeds and its correlation with aquatic locomotory behaviour.

Regional variation in the axial skeleton of pinnipeds (seals and walruses) and its correlation with aquatic locomotory behaviour is examined using vertebral functional profiles. The results demonstrate clear morpho-functional differences in the thoracolumbar region of modern pinnipeds (Phocidae, Otariidae, Odobenus) that can be strongly linked to swimming style. Phocid seals have a rigid thoracic region attached to a highly flexible lumbar region with long muscular lever arms providing the necessary mobility and leverage to perform pelvic oscillations. Conversely, otariid seals have extremely flexible inter-vertebral joints along the length of the column which should enhance manoeuvrability and turning performance. They also have greater muscular leverage in the anterior thoracic region to support pectoral oscillations. Odobenus (walrus) shows vertebral characteristics most similar to phocids, but with some otariid qualities, consistent with an intermediate or mixed form of aquatic locomotion, with pelvic oscillation dominating over pectoral oscillation. Comparison of the vertebral functional profiles in the fossil taxon Allodesmus kernensis with those of modern pinniped clades reveals that this extinct pinniped may also have used a combination of pectoral and pelvic oscillatory movements during swimming, but in a manner opposite to that of Odobenus, with pectoral oscillatory movements dominating. This study raises questions about the evolution and diversification of pinniped locomotory behaviours, but also provides the necessary framework to begin to examine axial mechanics and locomotory stages in other fossil pinnipedimorphs and their relatives in more detail.

Shape and mechanics in thalattosuchian (Crocodylomorpha) skulls: implications for feeding behaviour and niche partitioning.

Variation in modern crocodilian and extinct thalattosuchian crocodylomorph skull morphology is only weakly correlated with phylogeny, implying that factors other than evolutionary proximity play important roles in determining crocodile skull shape. To further explore factors potentially influencing morphological differentiation within the Thalattosuchia, we examine teleosaurid and metriorhynchid skull shape variation within a mechanical and dietary context using a combination of finite element modelling and multivariate statistics. Patterns of stress distribution through the skull were found to be very similar in teleosaurid and metriorhynchid species, with stress peaking at the posterior constriction of the snout and around the enlarged supratemporal fenestrae. However, the magnitudes of stresses differ, with metriorhynchids having generally stronger skulls. As with modern crocodilians, a strong linear relationship between skull length and skull strength exists, with short-snouted morphotypes experiencing less stress through the skull than long-snouted morphotypes under equivalent loads. Selection on snout shape related to dietary preference was found to work in orthogonal directions in the two families: diet is associated with snout length in teleosaurids and with snout width in metriorhynchids, suggesting that teleosaurid skulls were adapted for speed of attack and metriorhynchid skulls for force production. Evidence also indicates that morphological and functional differentiation of the skull occurred as a result of dietary preference, allowing closely related sympatric species to exploit a limited environment. Comparisons of the mechanical performance of the thalattosuchian skull with extant crocodilians show that teleosaurids and long-snouted metriorhynchids exhibit stress magnitudes similar to or greater than those of long-snouted modern forms, whereas short-snouted metriorhynchids display stress magnitudes converging on those found in short-snouted modern species. As a result, teleosaurids and long-snouted metriorhynchids were probably restricted to lateral attacks of the head and neck, but short-snouted metriorhynchids may have been able to employ the grasp and shake and/or 'death roll' feeding and foraging behaviours.

Use of the modified Delphi technique to identify and rate home injury hazard risks and prevention methods for young children.

OBJECTIVE: For children aged 1-5 years, the authors used the Delphi method to determine (1) the most important injury hazards in each area of the home; (2) the most important injury prevention behaviors; and (3) feasible and efficacious safety devices and behaviors to reduce injury risks. DESIGN: The authors used a modified Delphi method to prioritize home injury hazards for children 1-5 years of age. The Delphi method is an indirect, anonymous, iterative process aimed at achieving consensus among experts; in this study, the authors queried key informants electronically. Thirty four key informants, primarily from the United States, participated in at least one of the three rounds of questionnaires. Responses were submitted by email or fax. Participants identified, rated, and ranked home injury hazards and prevention methods. RESULTS: The overall response rate for each survey ranged from 82% to 97%. Initially, 330 unique hazards and prevention behaviors/devices were identified in seven areas of the home. The 126 home injury hazards were rated based on frequency, severity, and preventability of injury; and the 204 behaviors and devices were rated by efficacy and feasibility. These experts rated firearms and pools as the most significant hazards, and smoke alarms and safe water temperature as the most important preventions. CONCLUSIONS: The modified Delphi method of consensus was useful to prioritize home injury hazards and prevention methods for children under the age of 6 years.

Rapid recent radiation of S-RNase lineages in Witheringia solanacea (Solanaceae).

Strong frequency-dependent selection as found in the self-incompatibility loci of flowering plants maintains allelic lineages for extremely long time scales, such that allelic genealogies can shed insight into long-term demographic patterns of species. Effective mutation rate, as well as demographic change such as population bottlenecks, can influence genealogical structure. In addition, loss of functionality at the self-incompatibility locus is likely to affect radiation rates. Partial sequences for 21 S-RNase alleles of the mid-elevation tropical species Witheringia solanacea were obtained in order to compare their substitution rates and genealogy with those of Witheringia maculata and two species in the closely related genus Physalis. Sequences for W. solanacea fell into the three clades within the Solanaceae already identified for the genus. Terminal branch lengths for W. solanacea, scaled to the total depth of its phylogeny, were intermediate between the unusually short terminal branches of W. maculata and those of the two Physalis species. In contrast to the Physalis species, where interspecific dN/dS for closely related alleles exceeded 1.0 to the same degree as did intraspecific dN/dS, in Witheringia only intraspecific comparisons showed an excess of nonsynonymous substitutions, suggesting postspeciation radiation of alleles. Alleles associated with lowered S-RNase production and self-compatibility showed extremely short terminal branches. In summary, it appears that rapid recent diversification of alleles characterizes the Witheringia lineages. In some cases, this rapid diversification can be attributed to relaxed constraints due to breakdown of self-incompatibility.

DNA interstrand cross-linking by a mycotoxic diepoxide.

The diepoxide mycotoxin (2R, 3R, 8R, 9R)-4,6-decadiyne-2,3:8,9-diepoxy-1,10-diol (repandiol) was both isolated from the mushroom Hydnum repandum and synthesized de novo. Repandiol was found to form interstrand cross-links within a restriction fragment of DNA, linking deoxyguanosines on opposite strands primarily within the 5'-GNC and 5'-GNNC sequences preferred by diepoxyoctane. However, repandiol was a significantly less efficient cross-linker than either of the diepoxyalkanes (diepoxyoctane and diepoxybutane) to which it was compared.