Gecko Adhesion in Space and Time: A Phylogenetic Perspective on the Scansorial Success Story.

An evolutionary perspective on gecko adhesion was previously hampered by a lack of an explicit phylogeny for the group and of robust comparative methods to study trait evolution, an underappreciation for the taxonomic and structural diversity of geckos, and a dearth of fossil evidence bearing directly on the origin of the scansorial apparatus. With a multigene dataset as the basis for a comprehensive gekkotan phylogeny, model-based methods have recently been employed to estimate the number of unique derivations of the adhesive system and its role in lineage diversification. Evidence points to a single basal origin of the spinulate oberhautchen layer of the epidermis, which is a necessary precursor for the subsequent elaboration of a functional adhesive mechanism in geckos. However, multiple gains and losses are implicated for the elaborated setae that are necessary for adhesion via van der Waals forces. The well-supported phylogeny of gekkotans has demonstrated that convergence and parallelism in digital design are even more prevalent than previously believed. It also permits the reexamination of previously collected morphological data in an explicitly evolutionary context. Both time-calibrated trees and recently discovered amber fossils that preserve gecko toepads suggest that a fully-functional adhesive apparatus was not only present, but also represented by diverse architectures, by the mid-Cretaceous. Further characterization and phylogenetically-informed analyses of the other components of the adhesive system (muscles, tendons, blood sinuses, etc.) will permit a more comprehensive reconstruction of the evolutionary pathway(s) by which geckos have achieved their structural and taxonomic diversity. A phylogenetic perspective can meaningfully inform functional and performance studies of gecko adhesion and locomotion and can contribute to advances in bioinspired materials.

Repeated evolution of digital adhesion in geckos: a reply to Harrington and Reeder.

We published a phylogenetic comparative analysis that found geckos had gained and lost adhesive toepads multiple times over their long evolutionary history (Gamble et al., PLoS One, 7, 2012, e39429). This was consistent with decades of morphological studies showing geckos had evolved adhesive toepads on multiple occasions and that the morphology of geckos with ancestrally padless digits can be distinguished from secondarily padless forms. Recently, Harrington & Reeder (J. Evol. Biol., 30, 2017, 313) reanalysed data from Gamble et al. (PLoS One, 7, 2012, e39429) and found little support for the multiple origins hypothesis. Here, we argue that Harrington and Reeder failed to take morphological evidence into account when devising ancestral state reconstruction models and that these biologically unrealistic models led to erroneous conclusions about the evolution of adhesive toepads in geckos.

Bayesian adaptive Markov chain Monte Carlo estimation of genetic parameters.

Accurate and fast estimation of genetic parameters that underlie quantitative traits using mixed linear models with additive and dominance effects is of great importance in both natural and breeding populations. Here, we propose a new fast adaptive Markov chain Monte Carlo (MCMC) sampling algorithm for the estimation of genetic parameters in the linear mixed model with several random effects. In the learning phase of our algorithm, we use the hybrid Gibbs sampler to learn the covariance structure of the variance components. In the second phase of the algorithm, we use this covariance structure to formulate an effective proposal distribution for a Metropolis-Hastings algorithm, which uses a likelihood function in which the random effects have been integrated out. Compared with the hybrid Gibbs sampler, the new algorithm had better mixing properties and was approximately twice as fast to run. Our new algorithm was able to detect different modes in the posterior distribution. In addition, the posterior mode estimates from the adaptive MCMC method were close to the REML (residual maximum likelihood) estimates. Moreover, our exponential prior for inverse variance components was vague and enabled the estimated mode of the posterior variance to be practically zero, which was in agreement with the support from the likelihood (in the case of no dominance). The method performance is illustrated using simulated data sets with replicates and field data in barley.

Coming to America: multiple origins of New World geckos.

Geckos in the Western Hemisphere provide an excellent model to study faunal assembly at a continental scale. We generated a time-calibrated phylogeny, including exemplars of all New World gecko genera, to produce a biogeographical scenario for the New World geckos. Patterns of New World gecko origins are consistent with almost every biogeographical scenario utilized by a terrestrial vertebrate with different New World lineages showing evidence of vicariance, dispersal via temporary land bridge, overseas dispersal or anthropogenic introductions. We also recovered a strong relationship between clade age and species diversity, with older New World lineages having more species than more recently arrived lineages. Our data provide the first phylogenetic hypothesis for all New World geckos and highlight the intricate origins and ongoing organization of continental faunas. The phylogenetic and biogeographical hypotheses presented here provide an historical framework to further pursue research on the diversification and assembly of the New World herpetofauna.

Bayesian prediction of breeding values by accounting for genotype-by-environment interaction in self-pollinating crops.

In self-pollinating populations, individuals are characterized by a high degree of inbreeding. Additionally, phenotypic observations are highly influenced by genotype-by-environment interaction effects. Usually, Bayesian approaches to predict breeding values (in self-pollinating crops) omit genotype-by-environment interactions in the statistical model, which may result in biased estimates. In our study, a Bayesian Gibbs sampling algorithm was developed that is adapted to the high degree of inbreeding in self-pollinated crops and accounts for interaction effects between genotype and environment. As related lines are supposed to show similar genotype-by-environment interaction effects, an extended genetic relationship matrix is included in the Bayesian model. Additionally, since the coefficient matrix C in the mixed model equations can be characterized by rank deficiencies, the pseudoinverse of C was calculated by using the nullspace, which resulted in a faster computation time. In this study, field data of spring barley lines and data of a 'virtual' parental population of self-pollinating crops, generated by computer simulation, were used. For comparison, additional breeding values were predicted by a frequentist approach. In general, standard Bayesian Gibbs sampling and a frequentist approach resulted in similar estimates if heritability of the regarded trait was high. For low heritable traits, the modified Bayesian model, accounting for relatedness between lines in genotype-by-environment interaction, was superior to the standard model.

Multiple-trait breeding values for parental selection in self-pollinating crops.

Using breeding values in parental selection of self-pollinating crops seems to be superior to conventional selection strategies, where selection is often based on several traits which are correlated among each other. However, analysing each trait separately can bias estimates of breeding values. This study examined responses to selection for total merit indices based on breeding values resulting from single- and multiple-trait best linear unbiased prediction (BLUP). We generated data for a multi-environment trial of a "virtual" parental population in which the phenotypic value of inbred lines was influenced by additive, additive-by-additive epistatic, year, location, block and genotype-by-environment interaction effects. Two traits with heritabilities of 0.7 and 0.3 and nine different correlation scenarios between traits (estimated phenotypic correlation ranging from -0.39 to +0.36) were simulated. Gain in selection response was greater for multiple-trait than for single-trait breeding values, especially if traits were negatively correlated. For all correlation scenarios, the overall standard errors of difference of multiple-trait predictors were lower than those of single-trait analysis.

Drought tolerance of selected Eragrostis species correlates with leaf tensile properties.

BACKGROUND AND AIMS: Previous studies on grass leaf tensile properties (behaviour during mechanical stress) have focused on agricultural applications such as resistance to trampling and palatability; no investigations have directly addressed mechanical properties during water stress, and hence these are the subject of this study. METHODS: Critical (lethal) relative water contents were determined for three species of grass in the genus Eragrostis varying in their tolerance to drought. Measurements were taken for leaf tensile strength, elastic modulus, toughness and failure load under different conditions of hydration, and light microscopy and histochemical analyses were undertaken. KEY RESULTS: Leaf tensile strength of fully hydrated leaves for the drought-intolerant E. capensis, the moderately drought-tolerant E. tef and the drought-tolerant E. curvula correlated well with drought tolerance (critical relative water content). Eragrostis curvula had higher tensile strength values than E. tef, which in turn had higher values than E. capensis. Measurements on the drought-tolerant grass E. curvula when fully hydrated and when dried to below its turgor loss point showed that tensile strength, toughness and the elastic modulus all increased under conditions of turgor loss, while the failure load remained unchanged. Additional tests of 100 mm segments along the lamina of E. curvula showed that tensile strength, toughness and the elastic modulus all decreased with distance from the base of the lamina, while again the failure load was unaffected. This decrease in mechanical parameters correlated with a reduction in the size of the vascular bundles and the amount of lignification, as viewed in lamina cross-sections. CONCLUSIONS: The results confirm that leaf mechanical properties are affected by both water status and position along the lamina, and suggest a positive correlation between leaf internal architecture, tensile strength, cell wall chemistry and tolerance to dehydration for grasses.

[Computer-based system for monitoring the course of intraocular inflammation]. / Computergestütztes System zur Verlaufskontrolle intraokularer Entzündungen.

BACKGROUND: Until now, there has been no consistent rating system for changes of intraocular inflammation. We present such a computer-based system. METHODS: This program is based on a FileMaker database. It is made of anterior and posterior uveitis scores on the basis of published evaluation guidelines of the International Ocular Inflammation Society (IOIS). An anterior uveitis score consisting of anterior chamber cells, flare, and perilimbal injection on the one hand and a posterior uveitis score consisting of vitreous haze, macula, and optic nerve head edema on the other hand are calculated. After adding visual acuity, intraocular pressure, and systemic dose of corticosteroids, all parameters can be visualized by a radar graph. RESULTS: This system of documentation is easy to handle and presents a simplified version of the disease course. The abstract visualization enables the patient to better understand the therapeutic management. CONCLUSIONS: The program presented here offers good opportunities for standardized monitoring of the disease course.

The natural history of temporal variant frontotemporal dementia.

BACKGROUND: The temporal variant of frontotemporal dementia (tvFTD) features asymmetric anterior temporal/amygdala degeneration as well as ventromedial frontal, insular, and inferoposterior temporal involvement. Left temporal atrophy has been linked to loss of semantic knowledge, whereas behavioral symptoms dominate the right temporal variant. OBJECTIVE: To investigate the first symptoms and the timing of subsequent symptoms in patients with left versus right tvFTD. METHODS: Twenty-six patients with tvFTD were identified. Six had right > left temporal atrophy (right temporal lobe variant [RTLV]) and were matched with six having comparable left > right temporal atrophy (left temporal lobe variant [LTLV]). Clinical records were reviewed to generate individualized symptom chronologies. RESULTS: In all patients, first symptoms involved semantics (4/6 LTLV, 1/6 RTLV), behavior (4/6 RTLV, 1/6 LTLV), or both (1 LTLV, 1 RTLV). Semantic loss began with anomia, word-finding difficulties, and repetitive speech, whereas the early behavioral syndrome was characterized by emotional distance, irritability, and disruption of physiologic drives (sleep, appetite, libido). After an average of 3 years, patients developed whichever of the two initial syndromes--semantic or behavioral--that they lacked at onset. A third stage, 5 to 7 years from onset, saw the emergence of disinhibition, compulsions, impaired face recognition, altered food preference, and weight gain. Compulsions in LTLV were directed toward visual, nonverbal stimuli, whereas patients with RTLV were drawn to games with words and symbols. CONCLUSIONS: The temporal variant of frontotemporal dementia follows a characteristic cognitive and behavioral progression that suggests early spread from one anterior temporal lobe to the other. Later symptoms implicate ventromedial frontal, insular, and inferoposterior temporal regions, but their precise anatomic correlates await confirmation.

Kinetics of lactate metabolism after submaximal ergometric exercise in HIV-infected patients.

OBJECTIVES: It is unknown whether high levels of lactate result from enhanced production or decreased degradation. We therefore investigated differences in the kinetics of plasma lactic acid in HIV-infected patients receiving or not receiving highly active antiretroviral therapy (HAART) and in uninfected controls after submaximal ergometric exercise. METHODS: Ten healthy controls, 11 HIV-infected therapy-naïve patients, 15 HIV-infected patients on HAART with normal baseline lactate levels, and nine HIV-infected patients on HAART with elevated baseline lactate levels >2 mmol/L performed 10 min of ergometric exercise, with a heart rate of 200 beats/min minus age. Lactate levels were measured at baseline, at the end of exercise and 15, 30, 45, 60 and 120 min thereafter. RESULTS: Mean baseline lactate levels were 1.4, 1.5, 1.5 and 2.8 mmol/L in the controls, the therapy-naïve patients, the patients on HAART with normal lactate levels and the patients on HAART with elevated lactate levels, respectively. Maximum lactate levels after exercise were similar in all groups (9.7, 9.4, 9.0 and 10.1 mmol/L, respectively). Significant differences were found in the slope of lactate decline between controls and untreated individuals (P=0.038) and between patients on HAART with normal baseline lactate and patients on HAART with elevated baseline lactate (P=0.028). CONCLUSIONS: Differences in lactate metabolism do exist between healthy controls and HIV-infected therapy-naïve individuals. Thus, HIV infection in itself may influence lactate levels. Elevated baseline lactate levels are associated with a delayed decline of lactate after exercise. These results could be explained by impaired lactate clearance. Lactate production upon exercise does not seem to be affected by baseline lactate levels.

Current trends of surgical management of head and neck carcinomas.

Surgery and radiotherapy remain the mainstays of treatment for head and neck cancer. Surgical resection and reconstructive techniques are improving and offer the potential for organ and function preservation. This article gives an overview of carcinomas of the head and neck, salivary glands, and thyroid including epidemiology, staging, pathology, and standard treatment.

Laryngotracheal morphology of Afro-Madagascan geckos: a comparative survey.

The structural variation of the gekkonid larynx and trachea is examined within a representative subset of 17 species of Afro-Madagascan gekkonines to determine if there are underlying morphological correlates of vocalization. The documented morphology is compared to that of the tokay (Gekko gecko), which has previously been described. Data were obtained from gross anatomical observations, scanning electron microscopy, histological examinations and computer-generated, three-dimensional, skeletal reconstructions. Although there is limited variation among most Afro-Malagasy gekkonids, the larynges of Ptenopus garrulus and Uroplatus fimbriatus exhibit marked degrees of differentiation, suggesting that laryngeal and tracheal morphology may account for the documented vocal variability of gekkonid lizards. Cladistic analyses indicated that parallel adaptive trends characterize the laryngeal morphology of the examined taxa. Alternate designs and refinements to a model of gekkonid phonation are presented, and the evolution of acoustic communication in the Gekkonidae is considered.

Adenocarcinoma of the small intestine: 21-year review of diagnosis, treatment, and prognosis.

BACKGROUND: The purpose of this study was to evaluate the tumor characteristics and treatment associated with an improved overall survival in patients with adenocarcinoma of the small intestine. METHODS: The records of all patients with primary adenocarcinoma of the small bowel seen between January 1971 and December 1991 were reviewed retrospectively. The study comprised 38 patients, 22 (58%) with duodenal tumors, 11 (29%) with jejunal tumors, and five (13%) with ileal tumors. RESULTS: Although not statistically significant, the patients with duodenal adenocarcinoma lived longer than the patients with jejunal or ileal lesions (p = 0.77). The overall survival was 23% and seemed to correlate best with absence of lymph node metastases (p = 0.04) and pancreaticoduodenectomy for localized duodenal tumors (p = 0.04). The patient's age, duration of symptoms, disease-free interval, tumor location, type of recurrence, and histologic grade did not significantly influence survival. CONCLUSIONS: The lethality of small-intestinal adenocarcinoma appears to be related to a delay in diagnosis and treatment. When a definitive surgical procedure is performed before lymph node metastases appear, the patient's chance for long-term survival is greatly improved.

Lungs of the gecko Rhacodactylus leachianus (Reptilia: Gekkonidae): a correlative gross anatomical and light and electron microscopic study.

The lungs of the New Caldeonian gecko Rhacodactylus leachianus were examined by means of gross dissection and light and electron microscopy. This tropical species, which is the largest living gecko, possesses two simple, single-chambered lungs. Right and left lungs are of similar size and shape. The lung volume (27.2 ml.100 g-1) is similar to that of the tokay (Gekko gecko) but differs in that the gas exchange tissue is approximately homogeneously distributed, and the parenchymal units (ediculae) are very large, approximately 2 mm in diameter. The parenchymal depth varies according to the location in the lung, being deepest near the middle of the lung and shallowest caudally. Scanning and transmission electron microscopy reveal an unusual distribution of ciliated cells in patches on the edicular walls as well as on the trabeculae. Secretory cells are very numerous, particularly in the bronchial epithelium, where they greatly outnumber the ciliated cells. The secretory cells form a morphological continuum characterized by small secretory droplets apically and large vacuoles basally. This continuum includes cells resembling type II pneumocytes but which are devoid of lamellar bodies. Type I pneumocytes similar to those of other reptiles cover the respiratory capillaries, where they form a thin, air-blood barrier together with the capillary endothelial cells and the fused basement laminae. The innervation, musculature, and vascular distribution in R. leachianus are also characterized. Apparent simplification of the lungs in this taxon may be related to features of its sluggish habits, whereas peculiarities of cell and tissue composition may reflect demands of its mesic habitat.

Tourette syndrome: a review and educational implications.

Tourette syndrome has recently been brought to public attention through popular media. This review of the literature is an effort to communicate to special educators and allied professionals in nonmedical terms the present state of the art with regard to the definition, symptoms, etiology, treatment, and educational implications of Tourette. The review is concluded with suggestions for the education of Tourette students.