ASPECTOS ESTRUTURAIS DE ALGUMAS NEOLIGNANAS HIDROBENZOFURÂNICAS

STRUCTURAL ASPECTS OF SOME HYDROBENZOFURAN NEOLIGNANS. The neolignans are defined as dimers of allylphenol and propenylphenol between itself or crossed, whose bond does not occur by the 8-8' carbons like lignans. This review centered on stereochemical aspects of the hydrobenzofuran type, a widespread skeleton among neolignans. The chemical structures established based on spectrometric data are registered in the literature. The absolute configurations reported previously were determined by chiroptical techniques. Some chemical transformations with neolignans, performed in previous studies, afforded products which are accumulated in other vegetal species and contributed to assign the unknown stereochemistry of these natural compounds. Possible biosynthetic pathways are also proposed.

Aspectos estruturais de algumas neolignanas hidrobenzofurânicas

The neolignans are defined as dimers of allylphenol and propenylphenol between itself or crossed, whose bond does not occur by the 8-8' carbons like lignans. This review centered on stereochemical aspects of the hydrobenzofuran type, a widespread skeleton among neolignans. The chemical structures established based on spectrometric data are registered in the literature. The absolute configurations reported previously were determined by chiroptical techniques. Some chemical transformations with neolignans, performed in previous studies, afforded products which are accumulated in other vegetal species and contributed to assign the unknown stereochemistry of these natural compounds. Possible biosynthetic pathways are also proposed.

How Old Is Luzia? Luminescence Dating and Stratigraphic Integrity at Lapa Vermelha, Lagoa Santa, Brazil

During an excavation in the 1970s, a disarticulated female human skeleton, later nicknamed Luzia, was discovered at 12m depth at Lapa Vermelha rockshelter in central Brazil. Radiocarbon dating of associated charcoal suggested an age of 11.4-16.4 ka for the skeleton. The scattering of the skeletal parts, some uncertainty about the exact provenience of the skeleton, and evidence of pervasive insect turbation in the archaeological layers have raised doubts about the accuracy of the age. Luminescence dates for the depositional ages of the sediments at Lapa Vermelha are reported here. Single-grain optically stimulated luminescence (OSL) of quartz along with grain-size, chemical and micro-morphological analyses of the sediments were employed to assess stratigraphic integrity, particularly the degree of sediment mixing. These various lines of evidence point to high stratigraphic integrity with little mixing at Lapa Vermelha. Sediments closest to where Luzia was recovered give OSL ages ranging from 12.7 to 16.0 ka, thus not refuting the original dates. (C) 2010 Wiley Periodicals, Inc.

The anatomy of the upper cretaceous snake Najash rionegrina Apesteguia & Zaher, 2006, and the evolution of limblessness in snakes

Najash rionegrina Apesteguia & Zaher, 2006, a terrestrial fossil snake from the Upper Cretaceous of Argentina, represents the first known snake with a sacrum associated with robust, well-developed hind limbs. Najash rionegrina documents an important gap in the evolutionary development towards limblessness, because its phylogenetic affinities suggest that it is the sister group of all modern snakes, including the limbed Tethyan snakes Pachyrhachis, Haasiophis, and Eupodophis. The latter three limbed marine fossil snakes are shown to be more derived morphologically, because they lack a sacrum, but have articulated lymphapophyses, and their appendicular skeleton is enclosed by the rib cage, as in modern snakes.

Developmental basis of limb homology in Pleurodiran turtles, and the identity of the hooked element in the chelonian tarsus

Although Pleurodiran turtles represent an important component of extant turtle radiation, our knowledge of the development and homology of limb bones in turtles rests mostly upon observations made on derived members of the Cryptodiran clade. Herein, we describe limb development in three pleurodirans: Podocnemis unifilis Troschel, 1848, Podocnemis sextuberculata Cornalia, 1849 and Phrynops hilarii (Dumeril and Bibron, 1835), in an effort to contribute to filling this anatomical gap. For earlier stages of limb development, we described the Y-shaped condensation that gave rise to the zeugopodial cartilages, and differentiation of the primary axis/digital arch that reveals the invariant pattern common to tetrapods. There are up to four central cartilaginous foci in the carpus, and the proximal tarsale is formed by the fusion of the fibulare, intermedium, and centrale 4. Digital development is similar for the five digits. Changes in toe V occur predominantly in the distal tarsale 5. Ontogenetic reduction of phalanges is observed in toe V of Podocnemis. Based on these results, we suggest that the hooked element present in the chelonian tarsus, and traditionally recognized as a modified fifth metatarsale, is actually the fifth distal tarsale. Additionally, our data on limb development of pleurodiran turtles supply more taxonomically comprehensive information to interpret limb configuration within the chelonian clade. (C) 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 155, 845-866.

On the Limit of Frequency of Electrochemical Oscillators and Its Relationship to Kinetic Parameters

The class of electrochemical oscillators characterized by a partially hidden negative differential resistance in an N-shaped current potential curve encompasses a myriad of experimental examples. We present a comprehensive methodological analysis of the oscillation frequency of this class of systems and discuss its dependence on electrical and kinetic parameters. The analysis is developed from a skeleton ordinary differential equation model, and an equation for the oscillation frequency is obtained. Simulations are carried out for a model system, namely, the nickel electrodissolution, and the numerical results are confirmed by experimental data on this system. In addition, the treatment is further applied to the electro-oxidation of ethylene glycol where unusually large oscillation frequencies have been reported. Despite the distinct chemistry underlying the oscillatory dynamics of these systems, a very good agreement between experiments and theoretical predictions is observed. The application of the developed theory is suggested as an important step for primary kinetic characterization.

Skeletal abnormalities in humpback whales Megaptera novaeangliae stranded in the Brazilian breeding ground

Skeletal tissues of 49 humpback whales Megaptera novaeangliae that stranded between 2002 and 2011 along the Abrolhos Bank seashore and its adjacent waters in Brazil were studied. Twelve (24.5%) animals presented pathological changes in one or more bones. Degenerative changes and developmental malformations were most frequent (10.2% each), followed by inflammatory/infectious and traumatic lesions (8.2% each). Infectious diseases led to severe lesions of the caudal vertebrae of 2 whales. In one of these individuals, the lesions involved 6 caudal vertebrae, leading to ankylosis of 3 vertebrae. Degenerative changes were observed in the vertebral columns of 3 animals, involving the joints of 13 ribs of 1 individual, and in the humerus of 1 whale. Traumatic lesions, such as osseous callus in the ribs, were observed in 4 animals. In 1 whale, the rib showed severe osteomyelitis, possibly resulting from the infection of multiple fractures. Developmental abnormalities such as spina bifida on 3 cervical vertebrae of 1 whale, fusion of spinal processes on thoracic vertebrae of 1 individual and fusion of the first 2 ribs unilaterally or bilaterally in 4 animals were found. Chronic infectious conditions found in the axial skeleton may have restrained spinal mobility and had detrimental effects on the general health of the animals, contributing to stranding and death. To our knowledge, this is the first systematic study on skeletal lesions in stranded humpback whales.

In Vitro Schistosomicidal Activity of Balsaminol F and Karavilagenin C

Five cucurbitane-type triterpenes (1-5), previously isolated from the African medicinal plant Momordica balsamina, along with five ester derivatives (6-10) of karavilagenin C (2), were evaluated for their potential schistosomicidal activity against Schistosoma mansoni adult worms. The natural compounds were isolated from the ethyl acetate-soluble fraction of the methanol extract of the aerial parts of M. balsamina. In a preliminary study, a significant schistosomicidal activity was observed for both the crude methanol extract and the ethyl acetate fraction. The compounds responsible for the activity were found to be balsaminol F (1) and karavilagenin C (2) with LC50 values of 14.7 +/- 1.5 and 28.9 +/- 1.8 mu M, respectively, after 24 h of incubation (positive control praziquantel, LC50 = 1.2 +/- 0.1 mu M). Both compounds (1, 2), at 10-50 mu M, induced significant reductions in the motor activity of the worms and significantly decreased the egg production. Furthermore, they were able (at 10-100 mu M) to separate the adult worm pairs into male and female after 24 h. Compounds 3-5, bearing a sugar moiety as a substituent, and the acylated derivatives of karavilagenin C (6-10) were inactive, suggesting that the presence of free hydroxyl groups in the tetracyclic skeleton might be important for the activity. A correlation between activity and the molecular volume/weight of compounds was also found.

Robust tori-like Lagrangian coherent structures

In general the term "Lagrangian coherent structure" (LCS) is used to make reference about structures whose properties are similar to a time-dependent analog of stable and unstable manifolds from a hyperbolic fixed point in Hamiltonian systems. Recently, the term LCS was used to describe a different type of structure, whose properties are similar to those of invariant tori in certain classes of two-dimensional incompressible flows. A new kind of LCS was obtained. It consists of barriers, called robust tori that block the trajectories in certain regions of the phase space. We used the Double-Gyre Flow system as the model. In this system, the robust tori play the role of a skeleton for the dynamics and block, horizontally, vortices that come from different parts of the phase space. (C) 2012 Elsevier B.V. All rights reserved.

Spectroscopic, Structural, and Conformational Properties of (Z)-4,4, 4-Trifluoro-3-(2-hydroxyethylamino)-1-(2-hydroxypheny1)-2-buten-1-one, C12H12F3NO3: A Trifluoromethyl-Substituted beta-Aminoenone

The ( Z)-4,4,4-trifluoro-3-(2-hydroxyethylamino)-1-(2-hydroxyphenyl)-2-buten-1-one (C12H12F3NO3) compound was thoroughly studied by IR, Raman, UV-visible, and C-13 and F-19 NMR spectroscopies. The solid-state molecular structure was determined by X-ray diffraction methods. It crystallizes in the P2(1)/c space group with a = 12.1420(4) angstrom, b = 7.8210(3) angstrom, c := 13.8970(5) angstrom, beta = 116.162(2)degrees, and Z = 4 molecules per unit cell. The molecule shows a nearly planar molecular skeleton, favored by intramolecular OH center dot center dot center dot 0 and NH center dot center dot center dot 0 bonds, which are arranged in the lattice as an OH center dot center dot center dot 0 bonded polymer coiled around crystallographic 2-fold screw-axes. The three postulated tautomers were evaluated using quantum chemical calculations. The lowest energy tautomer (I) calculated with density functional theory methods agrees with the observed crystal structure. The structural and conformational properties are discussed considering the effect of the intra- and intermolecular hydrogen bond interactions.

A palaeobiologist's guide to 'virtual' micro-CT preparation

This paper provides a brief but comprehensive guide to creating, preparing and dissecting a 'virtual' fossil, using a worked example to demonstrate some standard data processing techniques. Computed tomography (CT) is a 3D imaging modality for producing 'virtual' models of an object on a computer. In the last decade, CT technology has greatly improved, allowing bigger and denser objects to be scanned increasingly rapidly. The technique has now reached a stage where systems can facilitate large-scale, non-destructive comparative studies of extinct fossils and their living relatives. Consequently the main limiting factor in CT-based analyses is no longer scanning, but the hurdles of data processing (see disclaimer). The latter comprises the techniques required to convert a 3D CT volume (stack of digital slices) into a virtual image of the fossil that can be prepared (separated) from the matrix and 'dissected' into its anatomical parts. This technique can be applied to specimens or part of specimens embedded in the rock matrix that until now have been otherwise impossible to visualise. This paper presents a suggested workflow explaining the steps required, using as example a fossil tooth of Sphenacanthus hybodoides (Egerton), a shark from the Late Carboniferous of England. The original NHMUK copyrighted CT slice stack can be downloaded for practice of the described techniques, which include segmentation, rendering, movie animation, stereo-anaglyphy, data storage and dissemination. Fragile, rare specimens and type materials in university and museum collections can therefore be virtually processed for a variety of purposes, including virtual loans, website illustrations, publications and digital collections. Micro-CT and other 3D imaging techniques are increasingly utilized to facilitate data sharing among scientists and on education and outreach projects. Hence there is the potential to usher in a new era of global scientific collaboration and public communication using specimens in museum collections.

Sponges as substrata and early life history of the tubulariid Zyzzyzus warreni (Cnidaria: Hydrozoa) in the Sao Sebastiao Channel, Brazil

The hydroid Zyzzyzus warreni is usually found in shallow coastal waters forming aggregations of solitary polyps embedded in demosponges. Early life history transformations and settlement responses by the actinulae of this hydroid were studied in the laboratory using 13 species of sponges and 2 species of algae collected in the Sao Sebastiao Channel (Brazil) as substrata. The absence of oral tentacles and mouth in the actinulae and early events of metamorphosis suggest that these larvae are unable to spend long periods in the plankton and attach quickly near conspecifics when a preferred substratum is encountered. The time required for settlement and the number of elicited settlings indicated four settlement responses: (a) frequent and short-time settlement, in actinulae exposed to Halichondria cebimarensis, Mycale angulosa, M. aff. americana, M. laxissima (skeleton) and Tedania ignis; (b) moderate and delayed settlement, in actinulae exposed to Aplysina caissara, A. fulva, Haliclona melana and M. microsigmatosa; (c) no settlement, in actinulae exposed to Suberites aurantiacus and to the algae Hypnea musciformis and Sargassum cymosum; and (d) lethal response, in actinulae exposed to Amphimedon viridis, Aplysilla rosea, Dragmacidon reticulatum and M. laxissima. These responses indicate a considerable degree of species discrimination by the actinulae and are consistent with substrata used by the hydroid in the natural environment.

Skeletal development in the fossorial gymnophthalmids Calyptommatus sinebrachiatus and Nothobachia ablephara

The development of the cartilaginous and bony elements that form the skull and axial and appendicular skeleton is described in detail for the post-ovipositional embryonic development of the fossorial gymnophthalmid species Calyptommatus sinebrachiatus and Nothobachia ablephara. Both species have a snake-like morphology, showing an elongated body and reduced or absent limbs, as well as modifications in skull bones for burrowing, such as complex articulation surfaces and development of bony extensions that enclose and protect the brain. Similar morphological changes have originated independently in several squamate groups, including the one that led to the snake radiation. This study characterizes the patterns of chondrogenesis and osteogenesis, with special emphasis on the features associated with the burrowing habit, and may be used for future comparative analyses of the developmental patterns involved in the origin of the convergent serpentiform morphologies. (C) 2012 Elsevier GmbH. All rights reserved.

On wing disparity and morphological variation of the Santana Group pterosaurs

Pterosaurs were widely spread throughout the Mesozoic Era, populating the whole world. Among this great diversity, two groups are commonly found in Brazil: the Anhangueridae and Tapejaridae. These can be mainly identified by cranial synapomorphies. However, because of the fragility of the pterosaur skeleton and rarity of the fossilisation process, the fossils found are usually incomplete, which hampers a proper taxonomic identification of the specimens. The specific proportions of these two groups of pterosaurs were obtained from bibliographic data and measurements of specimens. Eight Anhangueridae-like and seven Tapejaridae were used: Anhanguera piscator, Anhanguera santanae, Anhanguera spielbergi, Araripesaurus castilhoi, Barbosania gracilisrostris and three Anhangueridae sp. indet.; Sinopterus dongi, Tapejara wellnhoferi and five Tapejaridae sp. indet. We find that proportions of the humerus, wing metacarpal, first phalanx of the wing digit, femur and tibia are sufficient to identify partial remains of Araripe pterosaurs. A principal component analysis shows that each clade has different, non-overlapping scores in the studied ratios and these can be used with precision. Specific bone ratios for fast identification of anhanguerids and tapejarids are given, opening a broader way to diagnostic fragmentary bones.

Solvent Effect in Reactions Using Stryker's Reagent

The solvent has a significant influence in the rate of reactions promoted by Stryker's reagent The reactions performed in THF were, in most cases, faster than in toluene.