Is (9Z)‐“meso”‐zeaxanthin optically active?

The question raised in the title was answered. (3R, 3'S)-meso-Zeaxanthin was submitted to iodine catalyzed photochemical stereoisomerisation. The enantiomeric (9Z) and (9'Z) geometrical isomers were isolated by semipreparative HPLC and separated as diastereomeric dicarbamates on a chiral column only. Cleavage of the carbamate could not be effected. CD-Spectra of (1"S, 1"S)- and (1"R, 1"R)-dicarbamates of geometrical isomers of (3R, 3'R)- and (3R, 3'S)-meso-zeaxanthin were systematically studied and the contribution from the carbamate moieties revealed. It was concluded that (9Z, 3R, 3'S)-"meso"-zeaxanthin, in spite of having no symmetry elements, is optically inactive. The result has been rationalised in line with the current hypothesis on the origin of carotenoid CD spectra.     

Does “supersaturated coexistence” resolve the “paradox of the plankton”?

In contradiction with field observations, theory predicts that the number of coexisting plankton species at equilibrium cannot exceed the number of limiting resources, which is called the "paradox of the plankton". Recently, Huisman & Weissing (1999 , 2000 ) showed, in a model study, that the number of coexisting species may exceed the number of limiting resources when internal system feedback induces oscillations or chaos. In this paper, we use the term "supersaturated coexistence" for this phenomenon. On the basis of these findings, they claimed that the paradox of the plankton is solved. We investigated the prerequisites for supersaturated coexistence in the same model. Our results indicate that supersaturated coexistence is a rare phenomenon in parameter space, requires a very precise parameterization of the community members and is sensitive to the introduction of new species and the removal of the present species. This raises the question of whether supersaturated coexistence is likely to occur in nature. We conclude that the claim by Huisman & Weissing (1999 , 2000 ) is premature.     

Revisiting “what do tadpoles really eat?” A 10‐year perspective

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Étienne Geoffroy St.‐Hilaire: father of “evo‐devo”?

SUMMARY In the early decades of the nineteenth century, the most important disagreement among comparative anatomists was not evolution versus "special creation" but between advocates of "transcendental morphology" and those of teleological anatomy—form versus function. In France this dichotomy was represented by the 1830–1832 public debate between Geoffroy St.-Hilaire (form) and Cuvier (function). Geoffroy's aim was to establish links of homology (known to him as "analogies") between the four "embranchements" into which Cuvier had divided the animal kingdom. Despite the fanciful nature of some of his homologies, Geoffroy, who was guided by his " principe de connections ," set in motion a school of morphology, some of whose conclusions, notably the homology of the dorsal surface of segmented invertebrates with the ventral surface of vertebrates, has been corroborated by recent studies in developmental genetics.     

Are the Kow Swamp hominids “archaic”?

Initial reports of hominids recovered at Kow Swamp, in the Murray Valley of Victoria indicated that, on the basis of cranial analyses, there was a "survival of Homo erectus features in Australia until as recently as 10,000 years ago (Thorne and Macumber, 1972, p. 316). This claim was later refuted by others, who suggested that artificial cranial deformation may have been responsible for at least some of the distinctive and "primitive" traits seen in the Kow Swamp individuals. Previous research by this worker and others has indicated that taxonomic traits at both specific and subspecific levels are present in hominine femora. Therefore, it may be possible to evaluate the "primitiveness" of the Kow Swamp sample on the basis of their femoral anatomy. Morphometric analyses were undertaken, using as controls femora of Romano British, Tasmanian, and other Murray Valley populations. On the basis of bivariate and multivariate analyses it was found that, at least in this single element of the postcranium, no primitive features were present. The Kow Swamp sample, in fact, shows a very close morphometric relationship with all included Homo sapiens controls and is significantly distinct from Homo erectus.     

Gibt es einen „Duft der MHC‐Gene“?

MHC‐Genes: Do they influence the choice of partners via olfactory signals? Behavioral experiments in mice and humans suggest that genes of the major histocompatibilty complex (MHC) may be important for the differentiation of self and non‐self during mate choice. While this correlation is well documented for certain mouse strains, it is controversial for humans. Signal transfer between potential partners is considered to occur via the production of MHC‐dependent olfactory cues by a sender and their recognition by olfaction in the recipient. It is shown that in mice and humans the overall bouquet of volatiles is not and the pattern of peptides in mice is only marginally influenced by the MHC genes. However, in mice, olfactory cues without MHC contribution appear to play a role in mate choice, in that the profile learned from the parents during rearing is compared with the distinct profile of a potential partner, which is in turn selected for mating. Such olfactory differentiation between close relatives and potential mates without MHC‐contribution may also operate unconsciously in humans.     

“New”‐clear functions of PDK1: Beyond a master kinase?

Activation of cytosolic phosphoinositide-3 kinase (PI-3K) signaling pathway has been well established to regulate gene expression, cell cycle, and survival by feeding signals to the nucleus. In addition, strong evidences accumulated over the past few years indicate the presence of an autonomous inositol lipid metabolism and PI-3K signaling within the nucleus. Much less, however, is known about the role and regulation of this nuclear PI-3K pathway. Components of the PI-3K signaling pathway, including PI 3-kinase and its downstream kinase Akt, have been identified at the nuclear level. Consistent with the presence of a complete PI-3K signaling pathway in the nucleus, we have recently found that phosphoinositide-dependent kinase 1 (PDK1), a kinase functioning downstream of PI-3K and upstream of Akt, is a nucleo-cytoplasmic shuttling protein. In the present review, we update our current knowledge on the regulatory mechanisms and the functional roles of PDK1 nuclear translocation. We also summarize some of the kinase-independent activities of PDK1 in cell signaling.     

Who Is the King? The α‐Hydroxy‐β‐oxo‐α,β‐enone Moiety or the Catechol B Ring: Relationship between the Structure of Quercetin Derivatives and Their Pro‐Oxidative Abilities

Quercetin and other flavonoids have been reported to exhibit both antioxidant and pro‐oxidant properties. Most studies about the pro‐oxidative ability were conducted in the presence of metal ions, and the essential functional moiety of quercetin responsible for the pro‐oxidative effect is still unclear. In this study, we evaluated the pro‐oxidative abilities in the absence of metal ions of two quercetin derivatives, i.e., quercetin‐3′‐O‐β‐D ‐glucoside ( 1 ) and quercetin‐3‐O‐β‐D ‐glucoside ( 2 ), by assessing DNA cleavage and HO^.‐radical production. The binding mode between these compounds and DNA was studied by fluorescence and viscometric titrations. The results showed that 1 can efficiently induce oxidative damage to plasmid DNA, while 2 shows poor activity. Both 1 and 2 bind to DNA via groove‐binding. These results proved that the α‐hydroxy‐β‐oxo‐α,β‐enone moiety contributes to the pro‐oxidative activity of quercetin.     

Survivin study: An update of “What is the next wave?”

Studies on survivin over the past 2-3 years have shown that survivin possesses multiple subcellular localizations and is a multifunctional molecule involved in many aspects of cellular processes and/or behaviors. The subcellular localization and function of the survivin splice variants, however, have not yet been well elucidated. We have, therefore, provided additional observations on several survivin splice variants for further exploration. This review article will update the role of survivin, and its splice variants in the mitosis/cell cycle, apoptosis, tumorigenesis, chemoprevention, drug/radiation resistance, and cancer therapeutics.     

Parrot claylick distribution in South America: do patterns of “where” help answer the question “why”?

Geophagy is well known among some Neotropical parrots. The clay apparently adsorbs dietary toxins and/or provides supplemental nutrients. We used location data and 23 environmental layers to develop a predictive model of claylick distribution using Maxent software. We related species characteristics to claylick use and examined how parrot assemblages using claylicks changed with distance from the centre of claylick distribution. Fifty‐two parrot claylicks were reported from an area of ca 4 million km² but over 50% were restricted to a 35 000 km² region of southeast Peru and northern Bolivia. Claylicks were strongly associated with moist forest on younger (<65 millions of yr) geological formations and exposed river banks. The predictive model of claylick distribution matched our reported range well, with precipitation of warmest quarter, land cover, temperature seasonality, and distance from the ocean being most important predictors of claylick presence. Twenty‐six of the region's 46 parrot species visited claylicks. Species differed greatly in their lick use, but body size, dietary breadth, abundance and other traits were poor predictors of lick use. We are confident that our survey identified the distribution of major parrot claylicks in South America, although less conspicuous parrot geophagy may occur elsewhere. We suggest that claylick distribution reflects both underlying geology (allowing claylick formation in only some regions) and the physiological need for geophagy among parrots in different parts of the continent. Data on the latter are inconclusive, but we argue that parrot claylick distribution supports the contention that geophagy is related more to sodium deficiencies than to protection from dietary toxins.     

Does the “C3 effect” offset the Δ2 effect,as regards the solution flexibility of aldoses?

The solution flexibility of carbohydrates influences a variety of molecular recognition and regulatory processes. For aldoses and other monosaccharides, this flexibility is dictated by the orientations of the various hydroxyl (OH) groups present, which influences conformer and anomer ratios, interactions among these OH groups, and interactions between them and the surrounding solvent. Depending on the number and position of axial OH groups, a variety of structures can coexist in solutions at equilibrium. In 1950, as part of his pioneering studies on the shape of pyranoside rings, Reeves described the Δ2 effect, the greater destabilization of the pyranose ring conformation when the OH group on carbon 2 (C₂) is in the axial position. It was later proposed by Angyal that the Δ2 effect could be cancelled by the presence of an axial OH on C₃, termed here the “C₃ effect.” Employing size‐exclusion chromatography, an entropically‐controlled separation technique, we have investigated whether or not the C₃ and Δ2 effects indeed do compensate for one another with respect to their influence on the solution flexibility of select aldohexoses and aldopentoses. As will be seen, while qualitatively and semiquantitatively this mutual cancellation of effects does occur in aldohexoses, it does not appear to do so in aldopentoses. An explanation for the latter appears to lie in the variety of anomers and conformers present in equilibrium solutions of those aldopentoses studied and in the relative entropic contribution of individual conformers or anomers to the total solution flexibility. © 2013 Wiley Periodicals, Inc. Biopolymers 101: 703–711, 2014.     

“The” genetic code?

The DNA‐based code for protein through messenger and transfer RNA is widely regarded as the code of life. But genomes are littered with other kinds of coding elements as well, and all of them probably came after a supercode for the tRNA system itself.     

How “representative” is the Terry collection? Evidence from the proximal femur

The work reported here is the beginning of an attempt to determine whether data on skeletal aging changes derived from the Terry collection (Smithsonian Institution) can safely be applied to present-day clinical and forensic problems. Measurements made on radiographs of the proximal third of the right femur below the greater trochanter were compared in three groups of American white females: Terry collection “regulars,” Terry collection willed, and GW (George Washington University Medical Center) willed. Mean birth year for the Terry regulars was 1883, whereas the mean birth year for Terry and GW willed was 1910. Terry willed femora are longer than those of Terry regulars, but not more robust. The two groups show opposing secular trends in femoral length, and in this respect the Terry regulars appear closer to the general U.S. population. In two indices of relative medullary cavity size (which reflect changes in cortical thickness as well as internal and external diameters) all three groups agree in showing age-related increase of medullary diameters, greater increase in the anterior–posterior dimension, and greatest amount of increase at diaphyseal levels. The major difference between groups is in timing, with medullary cavity expansion becoming evident at least a decade earlier and leading to greater eventual loss of cortical thickness in the willed groups.     

“How pendulum‐like are siamangs? energy exchange during brachiation”

Hylobatidae (gibbons and siamangs) are known for their brachiation skills. The comparison of brachiation with a pendulum is made several times in the literature, and the costs and benefits of being pendulum-like are well described. However, the amount of energy exchange during brachiation of gibbons has rarely been determined. In this study, the amount of energy recovery (ER) during brachiation is assessed for three siamangs in a seminatural environment. The animals were recorded by four cameras while voluntarily brachiating on three different setups. The effects of locomotion speed, brachiation type, and setup on ER as well as on the external mechanical work during brachiation are determined. It is hypothesized that the amount of ER decreases with an increasing setup complexity while the external mechanical work increases. Additionally, we expect that support arm kinematics will be adjusted according to spatial complexity in order to maintain high recovery percentages. Our results show that ER is mainly determined by brachiation speed. Regardless of type of brachiation or setup, brachiation is done with a lower ER when brachiating faster. Within our limited range of setup variation, the expected effect of increasing complexity is not found. Although there is significant variation in support arm joint angles, no clear relation with speed, brachiation type, or setup is observed.     

Was heißt “lebendig”?

“Life” means “being alive” of special entities, which we call “organisms”. From a physical point of view, living entities are open systems, which exchange matter as well as energy with their surroundings. Against disruptive influences permanently present, they maintain actively and autonomously a steady state far from the thermodynamic equilibrium. This dynamic state of living beings represents a functional order, an internal “organization”. That means that the involved processes one and all must be correlated in such a way that they in sum prevent the breakdown of the living state. Organization implies functionality, which in turn requires structural relationships, and structures require information for their specification. Information in turn presupposes a source, which is constituted in living systems by the nucleic acids. Organisms are unique in having a capacity to use information, which is stored in the nucleic acid and yields the basis for their specific internal organization in its perpetuation: Living beings, and only they, show a self‐maintained organization.