Ornamental colors reveal age in the king penguin

We investigated whether delayed plumage maturation occurred in king penguins (Aptenodytes patagonicus). Therefore we examined the relationships between age and sex on spectral properties and size of two colored plumage patches and a UV-reflective beak spot, using known-age cohorts. Unlike the colored patch on the breast, we found age differences in ear and beak coloration. These results suggest that head ornaments in king penguins could signal sexual maturity or social status. No sex differences were found in the intensity of colored ornaments, which can result from mutual mate choice or genetic correlation between sexes. Size of colored patches did not relate to age or sex.     

Fossilized eggs from the Pennsylvanian of Illinois

Nine siderite concretions from the Middle Pennsylvanian, Francis Creek Shale (Carbondale Formation, Desmoinesian Series, West‐phalian C‐D), in the Mazon Creek area, Will‐Kankakee Counties, Illinois, U.S.A. preserve clusters of impressions of small eggs. Differential staining of the matrix suggests that the eggs were originally spawn within gelatinous strings containing 1 or 2 rows of eggs. Unfortunately, these egg impressions lack the diagnostic features needed to identify the zoological taxon (taxa) from which they originated.     

Fossil-calibrated molecular phylogenies reveal that leaf-mining moths radiated millions of years after their host plants

Coevolution has been hypothesized as the main driving force for the remarkable diversity of insect-plant associations. Dating of insect and plant phylogenies allows us to test coevolutionary hypotheses and distinguish between the contemporaneous radiation of interacting lineages vs. insect 'host tracking' of previously diversified plants. Here, we used nuclear DNA to reconstruct a molecular phylogeny for 100 species of Phyllonorycter leaf-mining moths and 36 outgroup taxa. Ages for nodes in the moth phylogeny were estimated using a combination of a penalized likelihood method and a Bayesian approach, which takes into account phylogenetic uncertainty. To convert the relative ages of the moths into dates, we used an absolute calibration point from the fossil record. The age estimates of (a selection of) moth clades were then compared with fossil-based age estimates of their host plants. Our results show that the principal radiation of Phyllonorycter leaf-mining moths occurred well after the main radiation of their host plants and may represent the dominant associational mode in the fossil record.     

Sequence comparisons of odorant receptors among tortricid moths reveal different rates of molecular evolution among family members

In insects, odorant receptors detect volatile cues involved in behaviours such as mate recognition, food location and oviposition. We have investigated the evolution of three odorant receptors from five species within the moth genera Ctenopseustis and Planotrotrix, family Tortricidae, which fall into distinct clades within the odorant receptor multigene family. One receptor is the orthologue of the co-receptor Or83b, now known as Orco (OR2), and encodes the obligate ion channel subunit of the receptor complex. In comparison, the other two receptors, OR1 and OR3, are ligand-binding receptor subunits, activated by volatile compounds produced by plants--methyl salicylate and citral, respectively. Rates of sequence evolution at non-synonymous sites were significantly higher in OR1 compared with OR2 and OR3. Within the dataset OR1 contains 109 variable amino acid positions that are distributed evenly across the entire protein including transmembrane helices, loop regions and termini, while OR2 and OR3 contain 18 and 16 variable sites, respectively. OR2 shows a high level of amino acid conservation as expected due to its essential role in odour detection; however we found unexpected differences in the rate of evolution between two ligand-binding odorant receptors, OR1 and OR3. OR3 shows high sequence conservation suggestive of a conserved role in odour reception, whereas the higher rate of evolution observed in OR1, particularly at non-synonymous sites, may be suggestive of relaxed constraint, perhaps associated with the loss of an ancestral role in sex pheromone reception.     

Biophysical studies with AICD-47 reveal unique binding behavior characteristic of an unfolded domain

APP intracellular C-terminal domain (AICD-47), generated upon γ-secretase cleavage of amyloid precursor's protein (APP), bears the signature of a classical intrinsically unstructured domain (IUD). Comparing the recent crystal structures of AICD-47 peptides bound to its different adaptors such as protein-tyrosine-binding domain-2 (PTB2) of Fe65 and Src homology 2 (SH2) domain of growth factor receptor binding protein 2 (Grb2), the "conformational switching" of AICD-47 becomes evident. In order to understand different binding processes undertaken by this flexible molecule, upon recognizing different interfaces resulting in different 3D conformations, spectroscopic and calorimetric studies have been done. CD spectroscopy has revealed an overall random coil like structure in different pHs while TFE (2'-2'-2'-trifluoro ethanol) and HFIP (Hexa fluoro isopropanol) induced α-helicity to a certain extent. Binding of Tyr phosphorylated AICD-47 ((P)AICD-47) to Grb2-SH2 domain was carried out by a favorable enthalpic change (ΔH=-197.5±6.2kcalmole(-1) at 25°C) and an unfavorable entropic contribution (ΔS=-631calmol(-1)deg(-1) at 25°C). Alternative conformation of AICD-47 in different biological contexts is another remarkable feature of IUDs which presumably has definitive roles in regulating Alzheimer's disease phenotype.     

Facilitation of tiger moths by outbreaking tussock moths that share the same host plants

1.?Ecologists have argued about the commonness and strength of interspecific competition between insect herbivores, but facilitation between herbivores has received much less consideration. We previously found that when two species of folivorous caterpillars co-occurred on a shared host plant, feeding by early season tiger moth caterpillars reduced the growth and reproduction of later season tussock caterpillars. However, densities of tussock caterpillars in summer were positively correlated with densities of tiger moth caterpillars the following spring. 2.?In this study, we experimentally manipulated numbers of feeding tussock caterpillars and found that they facilitated tiger moth caterpillars. 3.?The depth of the litter layer beneath host lupine bushes was positively correlated with the number of tussock caterpillars feeding on each bush. Experimental additions of litter beneath lupine canopies during summer resulted in increased numbers of tiger moth caterpillars in the following spring, indicating a causal role of litter. Litter potentially provides food, habitat and protection from desiccation and predation. We failed to find evidence that tussock caterpillars facilitated tiger moth caterpillars by mechanisms independent of litter. 4.?Our study demonstrates that facilitation may operate between insect herbivores, across life-stages through indirect interactions that are non-trophic. Facilitation operated by a novel mechanism, the accumulation of litter which was a by-product of feeding by one species was valuable to a second species. Facilitation persisted in time and space far beyond the creation of litter by tussock caterpillars which should be considered important ecosystem engineers from the point of view of tiger moths. Facilitations that involve habitat modification may generally connect species that do not interact directly or trophically, and have not previously been considered to affect one another.     

Morphological and biochemical analyses of original and regenerated lizard tails reveal variation in protein and lipid composition

Caudal autotomy, or voluntary self-amputation of the tail, is a common and effective predator evasion mechanism used by most lizard species. The tail contributes to a multitude of biological functions such as locomotion, energetics, and social interactions, and thus there are often costs associated with autotomy. Notably, relatively little is known regarding bioenergetic costs of caudal autotomy in lizards, though key morphological differences exist between the original and regenerated tail that could alter the biochemistry and energetics. Therefore, we investigated lizard caudal biochemical content before and after regeneration in three gecko and one skink species. Specifically, we integrated biochemical and morphological analyses to quantify protein and lipid content in original and regenerated tails. All lizards lost significant body mass, mostly protein, due to autotomy and biochemical results indicated that original tails of all species contained a greater proportion of protein than lipid. Morphological analyses of two gecko species revealed interspecific differences in protein and lipid content of regenerated lizard tails. Results of this study contribute to our understanding of the biochemical consequences of a widespread predator evasion mechanism.     

Acoustic response of the B cell in noctuid moths

Spike activity of the B cell, a unit in the tympanic organ of noctuid moths, was monitored during both stationary flight and acoustic stimulation. This neuron was previously considered (Treat and Roeder, 1959) unresponsive to sound and was thought to be a sensor for thoracic deformations accompanying flight movements. The present study did not reveal changes in B cell spike repetition rate related to active wing flapping, but did reveal a decline in the tonic repetition rate with the onset of an acoustic stimulus. Experimental results indicate that this inhibition of B spike activity is, at least in part, indirect, with the acoustic sense cells serving as the primary receptors. B cell inhibition is most marked with rapidly pulsed, relatively intense bursts of ultrasound. Lowintensity continuous tones evoke little or no change in the B spike repetition rate. The relationship between B spike activity and that of the acoustic sense cells (A cells) is complex. There is roughly an inverse correlation between the two spike activities with the onset and with the cessation of an acoustic stimulus, but B spike activity changes during the stimulus with no concomitant change in A cell spike activity. The possible significance of this complex functioning is considered in relation to avoidance behaviour in flying moths.     

Physiological characteristics of the tympanic organ in noctuoid moths

Summary We show the variations in the spike activity of both auditory receptors inSpodoptera frugiperda, Mocis latipes, Ascalapha odorata (Noctuidae),Maenas jussiae andEmpyreuma pugione (Arctiidae) immediately after 45 ms and 5 s acoustic stimuli at different intensities. The frequency of the applied stimuli was 34 kHz forE. pugione and 20 kHz for the other species. The electrical activity of the auditory receptors was recorded at the tympanic nerve with a stainless steel hook electrode. When the 45 ms pulses cease there is an afterdischarge from both auditory receptors in all the species. The number of spikes in the afterdischarge activity of both receptor cells (A₁ and A₂) shows a linear relation with stimulus intensity (Table 1). This number increases monotonically with increments in stimulus intensity, except for the A₁ cell activity inE. pugione, which decreases at intensities higher than 55 dB (Fig. 1). There are significant species-specific differences in the slope values of the number of spikes in the afterdischarge of both auditory receptors. After a 5 s stimulusM. latipes andM. jussiae show a rapid recovery of the standard spontaneous A₁-cell discharge level. Poststimulus A₁-cell spike activity inS. frugiperda shows a silent period, the duration of which increases with stimulus intensity (Fig. 3).E. pugione andA. odorata show such a silent period after low and moderately intense stimuli, but at high intensities the post-stimulus activity exceeds the pre-stimulus spontaneous discharge (Fig. 3). We demonstrate statistically that these variations cannot be explained by the random fluctuations of the standard spontaneous discharge. They are thus considered a silent and a rebound period respectively (Fig. 5). The presence and duration of either type of period seem to depend on the magnitude of the response to the acoustic stimulus. They thus seem related to the adaptation rate and the previously suggested existence of peripheral inhibitory interaction between the auditory receptors.     

Physiological characteristics of the tympanic organ in noctuoid moths

Summary The tympanic organ ofSpodoptera frugiperda, Mocis latipes, Erebus odorata (Noctuidae) andMaenas jussiae (Arctiidae) was stimulated with acoustic stimuli of 20 kHz, 45 ms and 5 s duration, and intensities ranging from 30 to 100 dB. The electric activity of the auditory receptors was recorded at the tympanic nerve with a stainless steel hook electrode. In all of these moth species there is an intensity range (ca. 20 dB) in which the response of each auditory receptor (A₁ and A₂ cells) to 45 ms pulses varies in a linear relation to the logarithm of stimulus intensity. For intensities higher than this value, depending on the species and the cell analysed, the spike discharge may continue to increase, may saturate or may diminish (Fig. 2). InE. odorata andM. latipes the A₁-cell response shows a decrease for stimulus intensities higher than 30 dB above the threshold. In the former species there is a statistically significant linear relation between the A₂-cell response and the decrease of the A₁-cell response, but this is not the case inM. latipes (Fig. 3). The similarity of the responses ofE. odorata to those described inEmpyreuma pugione (Coro and Pérez 1984) suggest that also in this noctuid species one may assume that the A₂ cell inhibits the A₁ receptor. In all of these moth species there is a maximum firing rate of the auditory cells at the beginning of the response to pure tones of 5 s and an exponential decrease of their discharge frequency with the course of time (Fig. 5). The analysed species differ in the adaptation rates of their auditory receptors. In all of these species the A₂ cell adapts more rapidly than the A₁ cell. In most of these species the stimulus intensity influences the adaptation rate of the auditory receptors (Fig. 7). These results are compared with data obtained by other authors, and it is concluded that there are more interspecific differences in the physiological characteristics of the auditory receptors in noctuoid species than those reported so far.Abbreviation AP action potential     

Physiological characteristics of the tympanic organ in noctuoid moths

Journal of Comparative Physiology A -     

Variation in some moths from the industrial north-west of England

A survey of five species of moth each showing different degrees of melanism was made in Greater Manchester and compared with samples from adjacent rural areas. The genetics of the various systems is discussed     

Mastering the complexity of DNA nanostructures

The self-assembly of oligodeoxynucleotides is a versatile and powerful tool for the construction of objects in the nanoscale. The strictly information-driven pairing of DNA fragments can be used to rationally design and build nanostructures with planned topologies and geometries. Taking advantage of the steadily expanding library of well-characterized DNA motifs, several examples of structures with different dimensionalities have appeared in the literature in the past few years, laying the foundations for a promising DNA-mediated, bottom-up approach to nanotechnology. This article focuses on recent developments in this area of research and proposes a classification of DNA nanostructures based on topological considerations in addition to describing strategies for tackling the inherent complexities of such an endeavor.     

Incidence of 47,XYY males: Implications of the production of 47,XYY offspring by 47,XYY males

Abstract

Chromosomally normal 46,XY males can have 47,XYY male offspring as a result of fertilization of a normal ovum by a YY spermatozoon, produced by nondisjunction in the second meiotic division or by mitotic nondisjunction of the Y chromosome in early stages of embryonic development of a 46,XY fetus. If such meiotic and mitotic nondisjunctions were random events and if these were the only source of 47,XYY males in the population, the incidence of 47,XYY males would remain constant. Two cases have been reported, however, in which 47,XYY males produced 47,XYY male offspring. If there are 47,XYY males who are a source of 47,XYY males in the population, there is the possibility that the incidence of 47,XYY males is changing. A discrete‐generation model is presented which describes (1) the change in incidence of 47,XYY males from one generation to the next; (2) the incidence at equilibrium; and (3) the incidence as a function of the probability that a 47.XYY male has a 47,XYY offspring, and as a function of the mean number of offspring of 47,XYY males relative to the mean number of offspring of 46,XY males.     

Discrimination of colors by the black-chinned hummingbird,Archilochus alexandri

Summary The color vision of a population of black-chinned hummingbirds was studied by behavioral methods. Birds were attracted to feeders equipped with tungsten lamps and interference filters. Results are based on counts of approximately 5700 visits by 92 ± 5 birds. Population size was estimated by mistnetting and marking 29 hummingbirds, 22 of which could be recognized individually during the course of the experiments.Following experience with red (620 nm) at all feeders, the birds showed a modest tendency to visit red (620 nm, 650 nm) and blue (490 nm) rather than intermediate greens and yellows. When sugar was presented at only one wavelength, however, choices became much sharper.When positions of the feeders were randomized, trained birds selected feeders on the basis of hue. Brightness was not used as a significant cue. This finding thus provides a more rigorous demonstration of color vision in hummingbirds than has heretofore been available.Either position or color could be learned in several hours (6–22 visits). Red (620 nm) and green (546 nm) were learned at the same rate. Two different (and opposing) color associations could be learned simultaneously at sites approximately 30 m apart.Discrimination of hue was measured following training to each of four wavelengths: 620, 590, 546, and 480 nm. Light from interference filters with transmission maxima at 546 and 550 nm were differentiated by the birds to a statistically significant extent. 546 and 590 nm appear to lie near the boundaries of hues; a boundary near 540 nm is found in pigeon but not human color vision.These experiments were supported by NIH grant EY00222. We are grateful to Nate Mandell for construction of the feeder-stimulators, to Vince Roth and the staff of the Southwestern Research Station for accommodating our special needs during the course of this work, and to the Bird Banding Laboratory of the Fish and Wildlife Service and the Arizona Fish and Game Department for granting the necessary permits to net and mark hummingbirds. We also thank Reed Pike of the Department of Structural Biology, Stanford University for unfailing help in preparing the illustrations.     

Chemical constraints on the evolution of olfactory communication channels of moths

It is estimated there are over 100,000 moth species (Lepidoptera) that produce sex pheromones comprising communication channels used in specific-mate-recognition systems (SMRS) involved in pre-zygotic mating isolation and speciation. About 1572 moth species have been found to use 377 pheromone components, the majority being alcohols, aldehydes or acetate esters of olefinic chains of 10-22 carbons. Since there are limited numbers of possible unsaturated (double bonded) E- and Z-configured isomers of these chains, there may be constraints on incipient species evolving new pheromone components, especially if they are utilized by existing species. Here I develop algorithms that count and name all possible structures of chains with or without a functional group. The results show that for acetate esters there are only seven or nine monounsaturated isomers of six or seven carbon chains, respectively, suggesting use of these compounds could limit the number of communication channels available for radiation of new species (no moths use these short chains). For commonly used 14-carbon chains with an acetate ester functional group, and 1-3 unsaturations, there are 1039 isomers. A total of 2,096,883 isomers were counted from all multiply unsaturated 10-22-carbon chain acetate esters. The number of possible signals quickly extends into millions when considering pheromone blends of 2-4 components used by most species. There should be little chemical constraint on evolution of new communication channels based on compounds of 10 or more carbons, even for closely related species (e.g. ermine moths, Yponomeuta).