Epidemiological analysis of rare polydactylies

Castilla, Eduardo E.; Fonseca, Regina Lugarinho da; Dutra, Maria da Graça; Bermejo, Eva; Cuevas, Lourdes; Martínez‐Frías, Maria‐Luisa

doi:10.1002/(sici)1096-8628(19961111)65:4<295::aid-ajmg10>3.0.co;2-p

Cited by 52 publications

(38 citation statements)

References 14 publications

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“…5 F and G). This finding is a high rate of abnormality, much greater than for the tetrapod limb (47,48). Darwin (8) predicted this kind of variability in On the Origin of Species by Means of Natural Selection, stating that "in those cases in which the modification has been comparatively recent and extraordinarily great .…”

Section: How Did the Star Evolve?mentioning

confidence: 99%

Evolution of brains and behavior for optimal foraging: A tale of two predators

Catania

2012

Proc. Natl. Acad. Sci. U.S.A.

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Star-nosed moles and tentacled snakes have exceptional mechanosensory systems that illustrate a number of general features of nervous system organization and evolution. Star-nosed moles use the star for active touch-rapidly scanning the environment with the nasal rays. The star has the densest concentration of mechanoreceptors described for any mammal, with a central tactile fovea magnified in anatomically visible neocortical modules. The somatosensory system parallels visual system organization, illustrating general features of high-resolution sensory representations. Starnosed moles are the fastest mammalian foragers, able to identify and eat small prey in 120 ms. Optimal foraging theory suggests that the star evolved for profitably exploiting small invertebrates in a competitive wetland environment. The tentacled snake's facial appendages are superficially similar to the mole's nasal rays, but they have a very different function. These snakes are fully aquatic and use tentacles for passive detection of nearby fish. Trigeminal afferents respond to water movements and project tentacle information to the tectum in alignment with vision, illustrating a general theme for the integration of different sensory modalities. Tentacled snakes act as rare enemies, taking advantage of fish C-start escape responses by startling fish toward their strike-often aiming for the future location of escaping fish. By turning fish escapes to their advantage, snakes increase strike success and reduce handling time with head-first captures. The latter may, in turn, prevent snakes from becoming prey when feeding. Findings in these two unusual predators emphasize the importance of a multidisciplinary approach for understanding the evolution of brains and behavior.neocortex | neuroethology S tar-nosed moles and tentacled snakes each have novel sensory appendages protruding from their faces. These appendages give both animals a unique appearance unparalleled among their peers-no other mammal or snake has comparable appendages ( Fig. 1). However, there is more than the bizarre appearance of these animals to attract our attention. Extreme sensory specializations often reveal general principles of nervous system function and organization that are less obvious in other species (1-7). More generally, extremes in morphology provide informative case studies in evolutionary biology. Indeed, Darwin (8) devoted a special section of On the Origin of Species by Means of Natural Selection to "Organs of extreme perfection and complication." One can argue whether these unusual species seem in some way perfected, but surprisingly, the complexity of the mole's star has been cited as evidence of a divine creator (9).My goal is to review recent studies of these two species beginning with star-nosed moles, the species for which we have the most information from many years of study. The mole's nose is exceptional not only in appearance but also in the high density of mechanoreceptors that covers the nasal rays and the complexity of the modular neocortical net...

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Section: How Did the Star Evolve?mentioning

confidence: 99%

Evolution of brains and behavior for optimal foraging: A tale of two predators

Catania

2012

Proc. Natl. Acad. Sci. U.S.A.

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“…The ozd mutation potentially affects a Shh regulatory element Disruptions in AP limb pattern are among the most common human birth defects (Castilla et al, 1996;Castilla et al, 1998), and understanding the affected developmental mechanisms is of significant clinical importance. Interestingly, studies in human and mouse have mapped several mutations and transgene insertions causing limb-specific AP patterning defects to a syntenic locus near or within the Limb region 1 (Lmbr1) gene, located less than 1 Mbp from the Shh coding region [ (Clark et al, 2001;Lettice et al, 2002), and references therein].…”

Section: Shh-dependent and -Independent Limb Skeletal Elementsmentioning

confidence: 99%

The chickoligozeugodactyly(ozd) mutant lacks sonic hedgehog function in the limb

et al. 2003

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We have analyzed a new limb mutant in the chicken that we nameoligozeugodactyly (ozd). The limbs of this mutant have a longitudinal postaxial defect, lacking the posterior element in the zeugopod(ulna/fibula) and all digits except digit 1 in the leg. Classical recombination experiments show that the limb mesoderm is the defective tissue layer in ozd limb buds. Molecular analysis revealed that theozd limbs develop in the absence of Shh expression, while all other organs express Shh and develop normally. NeitherPtc1 nor Gli1 are detectable in mutant limb buds. However,Bmp2 and dHAND are expressed in the posterior wing and leg bud mesoderm, although at lower levels than in normal embryos. Activation ofHoxd11-13 occurs normally in ozd limbs but progressively declines with time. Phase III of expression is more affected than phase II,and expression is more severely affected in the more 5′ genes. Interestingly, re-expression of Hoxd13 occurs at late stages in the distal mesoderm of ozd leg buds, correlating with formation of digit 1. Fgf8 and Fgf4 expression are initiated normally in the mutant AER but their expression is progressively downregulated in the anterior AER. Recombinant Shh protein or ZPA grafts restore normal pattern toozd limbs; however, retinoic acid fails to induce Shh in ozdlimb mesoderm. We conclude that Shh function is required for limb development distal to the elbow/knee joints, similar to the Shh-/-mouse. Accordingly we classify the limb skeletal elements as Shh dependent or independent, with the ulna/fibula and digits other than digit 1 in the leg being Shh dependent. Finally we propose that the ozd mutation is most likely a defect in a regulatory element that controls limb-specific expression of Shh.

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“…This is puzzling when one considers that mutations for POLYDACTYLY (see Glossary) are particularly common. In humans, for example, the most common anomaly at birth is the presence of an extra toe or finger 3,4 (0.l-0.2%). The extra digit can be rudimentary, or fully formed and functional.…”

Section: Introductionmentioning

confidence: 99%