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.

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.

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.

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.

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.

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.

The dating and correct citation of A.F.A. Wiegmann's "Amphibien" section of Meyen's Reise um die Erde, with a bibliography of Wiegmann's herpetological publications

Arend Friedrich August Wiegmann (1802–1841), who was based at Zoologisches Museum in Berlin, is most closely associated with Mexican herpetology through his publication of Herpetologia Mexicana (1834). However, he also made substantial contributions to the study of reptiles and amphibians of other regions, particularly South America and Asia. These were based on collections made by Franz Julius Ferdinand Meyen (1804–1840) on a journey around the world during 1830–1832 and were published as the “Amphibien” section of Meyen's Reise um die Erde. The dating of this work has been especially problematic and several versions of the paper exist. A combination of sources of evidence, both intrinsic and extrinsic to Wiegmann's own publications, strongly suggests that the date of publication of this work is late 1834, that a book version of the paper predated the more widely cited paper in Nova acta, and that all versions of Reise um die Erde postdate Herpetologia Mexicana. An annotated bibliography of Wiegmann's 29 herpetological publications is presented.

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.

Allozyme Evidence for the Phylogeny of Giant New Caledonian Geckos (Squamata: Diplodactylidae: Rhacodactylus), with Comments on the Status of R. leachianus henkeli

The phylogenetic analysis of allozyme characters within the New Caledonian giant geckos, genus Rhacodactylus, yields a pattern of relationships that is largely congruent with that derived from morphological data. A ‘total evidence’ approach, incorporating 13 allozyme and 29 morphological characters, yields a single most-parsimonious tree with the pattern: R. auriculatus ((R. leachainus (R. ciliatus, R. chahoua)) (R. sarasinorum, R. trachyrhynchus)). A phenetic analysis based on Nei’s genetic distance data results in a similar branching pattern. The genus Pseudothecadactylus is tentatively regarded as valid because allozyme data conflict strongly with morphological data that suggest that these geckos evolved from within Rhacodactylus. Allozymes and available morphological data do not support the recognition of the recently described subspecies R. leachianus henkeli.

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.

Caudal Morphology of the Knob-Tailed Geckos, Genus Nephrurus (Reptilia, Gekkonidae), With Special Reference to the Tail Tip

The tail of lizards in the Australian gekkonid genus Nephrurus bears a characteristically expanded distal tip, the caudal knob. Anatomical and histological investigation of the knob reveals it to be an integumentary derivative with a massively hypertrophied dermal component. The knob's structure indicates that it is probably used to monitor the environment by detecting mechanical stimuli via the profuse array of sensilla on its surface. The vascular supply to it suggests that the knob may also be involved in thermoregulation.

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.