The smell of success and failure: the role of intrinsic and extrinsic chemical signals on the social behavior of crayfish

Animals commonly modify their behavior in the presence of aconspecific or in response to signals. This is particularlytrue in the context of aggressive exchanges, which animals useto form networks of social relationships and to communicatesocial status associated with those relationships. Althoughhierarchical structures are a widespread phenomenon that hasbeen studied extensively, the dynamic communication processes,specifically chemical communication in this review, is relativelyoverlooked. In particular, it is the exchange of informationduring agonistic interactions that mediates hierarchies and/oralters the outcomes of agonistic interactions. Given the theoreticalappeal of these interactions, and the evolutionary importanceand taxonomic diversity associated with social hierarchies,it is not surprising that the sensory mechanisms involved inthe formation and maintenance of hierarchical structures havereceived recent attention. In crayfish, dominance is thoughtto be largely determined by physical superiority, where encountersare largely dyadic and fighting behavior is highly stereotyped.However, recent evidence has shown that the outcome of dyadicencounters are dependent upon a number of factors other thanphysical size, that include the exchange of chemical informationduring encounters, previous social history, and the intrinsicneurochemical state of opponents. We have attempted to providea comprehensive analysis of the extrinsic chemical processes(previous history, sensory communication, etc.) and intrinsicchemical processes (neurochemical state) that produce and maintaindominance relations and social hierarchies in crayfish. We hopethat this review will bring together a global picture of theprocesses that determine a crayfish's social standing and howintrinsic and extrinsic chemicals have substantial effects onaggressive states and agonistic bouts.     

August Weismann on Germ-Plasm Variation

August Weismann is famous for having argued against the inheritance of acquired characters. However, an analysis of his work indicates that Weismann always held that changes in external conditions, acting during development, were the necessary causes of variation in the hereditary material. For much of his career he held that acquired germ-plasm variation was inherited. An irony, which is in tension with much of the standard twentieth-century history of biology, thus exists – Weismann was not a Weismannian. I distinguish three claims regarding the germ-plasm: (1) its continuity,(2) its morphological sequestration, and (3) its variational sequestration. With respect to changes in Weismann's views on the cause of variation, I divide his career into four stages. For each stage I analyze his beliefs on the relative importance of changes in external conditions and sexual reproduction as causes ofvariation in the hereditary material. Weismann believed, and Weismannism denies, that variation, heredity, and development were deeply intertwined processes. This article is part of a larger project comparing commitments regarding variation during the latter half of the nineteenth century. This revised version was published online in July 2006 with corrections to the Cover Date.     

Applauding with Closed Hands: Neural Signature of Action-Sentence Compatibility Effects

Background

Behavioral studies have provided evidence for an action–sentence compatibility effect (ACE) that suggests a coupling of motor mechanisms and action-sentence comprehension. When both processes are concurrent, the action sentence primes the actual movement, and simultaneously, the action affects comprehension. The aim of the present study was to investigate brain markers of bidirectional impact of language comprehension and motor processes.

Methodology/Principal Findings

Participants listened to sentences describing an action that involved an open hand, a closed hand, or no manual action. Each participant was asked to press a button to indicate his/her understanding of the sentence. Each participant was assigned a hand-shape, either closed or open, which had to be used to activate the button. There were two groups (depending on the assigned hand-shape) and three categories (compatible, incompatible and neutral) defined according to the compatibility between the response and the sentence. ACEs were found in both groups. Brain markers of semantic processing exhibited an N400-like component around the Cz electrode position. This component distinguishes between compatible and incompatible, with a greater negative deflection for incompatible. Motor response elicited a motor potential (MP) and a re-afferent potential (RAP), which are both enhanced in the compatible condition.

Conclusions/Significance

The present findings provide the first ACE cortical measurements of semantic processing and the motor response. N400-like effects suggest that incompatibility with motor processes interferes in sentence comprehension in a semantic fashion. Modulation of motor potentials (MP and RAP) revealed a multimodal semantic facilitation of the motor response. Both results provide neural evidence of an action-sentence bidirectional relationship. Our results suggest that ACE is not an epiphenomenal post-sentence comprehension process. In contrast, motor-language integration occurring during the verb onset supports a genuine and ongoing brain motor-language interaction.     

Penelope as Dreamer: A Reading of Book 19 of The Odyssey

This essay reexamines the encounter between Odysseus and Penelope in Book 19 of Homer's epic poem The Odyssey, focusing particular attention on the dream of the 20 geese Penelope describes during that encounter. Odysseus, disguised as a beggar, says the dream is a favorable omen which indicates the real Odysseus will return soon to rid his palace of the hated suitors who have occupied it in his long absence. Although generations of scholars have agreed with the hero's interpretation, the present essay offers a different understanding: Penelope, having recognized who this beggar really is, has fabricated her dream of the 20 geese to test her husband and determine whether he is more interested in renewing their marriage or satisfying his vengeance against the suitors. The essay offers an appreciation of Penelope as one of our earliest and wisest dreamers, who understood how easily people's wishes and desires could lead them to misinterpret their own dreams and the dreams of others.     

Inheritance of the cephalic index

Using data from 462 paternity examinations, it was found that, (1) The cephalic index of an infant does not correlate at all closely to those of his or her parents as a pair, nor with that of the like sexed parent, but (2) The cephalic index of an infant, in a majority of cases, falls within a single percentage point of one of the two parents. Because of this it is hypothesized that this aspect of skullshape in inherited in a unitary fashion.     

Behavior analysis and neuroscience

Darwin proposed a powerful functional principle-natural selection-to interpret phylogenetic diversity and complexity. Nevertheless, some 70 years elapsed before even biologists embraced his account. The triumph of natural selection required two additional factors: (a) biological mechanisms that implemented the functional principle (i.e. genetics); and (b) quantitative procedures that traced its cumulative effects (i.e. population genetics). Thorndike and, later, Skinner proposed a functional principle-selection by reinforcement-that interpreted ontogenetic diversity and complexity. This principle has been substantially refined by subsequent experimental and theoretical work and now provides an equally powerful functional account. However, a purely functional principle has once again not persuaded most scientists (apart from the behavior-analytic minority) that complex behavior can be understood by a selection principle. If the history of ontogeny recapitulates the history of phylogeny, the biological mechanisms that implement selection by reinforcement must be discovered and quantitative techniques that trace its effects must be devised. In short, the triumph of reinforcement may await the integration of behavior analysis with the neurosciences and the development of coordinated quantitative procedures. This article identifies specific interrelations with neuroscience that form the basis for a behavior-analytically faithful interpretation of reinforcement using neural-network techniques. Implications for the architecture of networks and for the learning algorithm are emphasized.     

A bridge-builder: Wolf-Ernst Reif and the Darwinisation of German paleontology

Wolf-Ernst Reif was an outstanding German paleontologist, who, along with his empirical studies (biomechanics, functional and constructional morphology, etc.), paid significant attention to theoretical issues and the history of his discipline. Reif was a bridge-builder, skillfully synthesising history, theory and empirical studies within German-language paleontology. This paper briefly discusses sophisticated relationships between German paleontology and Darwinism based on the historical studies of Wolf-Ernst Reif. German paleontology did not fully embrace Darwinism until the 1970s. There are several reasons for this. First, alternative evolutionary theories (saltationism, neo-Lamarckism, orthogenesis) occupied a significant segment of the theoretical landscape in the German life sciences. Second, typological thinking persisted in German paleontology after the Second World War. Third, German paleontologists were relatively uninterested in discussing mechanisms of evolution, concentrating instead on reconstructing phylogenetic history.     

Responding Empathically: A Question of Heart,not a Question of Skin

Empathy entails the capacities to resonate with another person’s emotions, understand his/her thoughts and feelings, separate our own thoughts and emotions from those of the observed and responding with the appropriate prosocial and helpful behavior. While there is abundant research on the neurobiological mechanisms of some components of empathy (e.g., emotional contagion), few studies have considered the neurobiological mechanisms underlying the empathic response. The present study explores psychophysiological correlates (skin conductance level and the interbeat interval) as a function of the empathic response while participants watch and respond to actors portraying emotionally laden vignettes. Forty undergraduate psychology students were each presented with 40 emotional vignettes of positive or negative valence and asked to choose among three different empathic responses while their electrodermal and cardiac responses were measured. Overall, the study shows that higher levels of additive empathy are associated with increased cardiac activity (i.e., decreased Interbeat Interval) but not electrodermal activity.     

The cytogenetic architecture of the aphid genome

In recent years aphids, with their well‐defined polyphenism, have become favoured as model organisms for the study of epigenetic processes. The availability of the pea aphid (Acyrthosiphon pisum) genome sequence has engendered much research aimed at elucidating the mechanisms by which the phenotypic plasticity of aphids is inherited and controlled. Yet so far this research effort has paid little attention to the cytogenetic processes that play a vital part in the organisation, expression and inheritance of the aphid genome. Aphids have holocentric chromosomes, which have very different properties from the chromosomes with localised centromeres that are found in most other organisms. Here we review the diverse forms of aphid chromosome behaviour that occur during sex determination and male and female meiosis, often in response to environmental changes and mediated by endocrine factors. Remarkable differences occur, even between related species, that could have significant effects on the inheritance of all or parts of the genome. In relation to this, we review the particular features of the distribution of heterochromatin, rDNA genes and other repetitive DNA in aphid chromosomes, and discuss the part that these may play in the epigenetic modification of chromatin structure and function.     

Glacial refugia and reticulate evolution: the case of the Tasmanian eucalypts

Tasmania is a natural laboratory for investigating the evolutionary processes of the Quaternary. It is a large island lying 40-44 degrees S, which was repeatedly glaciated and linked to southeastern continental Australia during the Quaternary. Climate change promoted both the isolation of species in glacial refugia, and an exchange between Tasmanian and mainland floras. Eucalyptus is a complex and diverse genus, which has increased in abundance in Australia over the past 100 kyr, probably in response to higher fire frequency. Morphological evidence suggests that gene flow may have occurred between many eucalypt species after changes in their distribution during the Quaternary. This paper summarizes recent genetic evidence for migration and introgressive hybridization in Tasmanian Eucalyptus. Maternally inherited chloroplast DNA reveals a long-term persistence of eucalypts in southeastern Tasmanian refugia, coupled with introgressive hybridization involving many species. Detailed analysis of the widespread species Eucalyptus globulus suggests that migration from mainland Australia was followed by introgression involving a rare Tasmanian endemic. The data support the hypothesis that changes in distribution of interfertile species during the Quaternary have promoted reticulate evolution in Eucalyptus.     

A.N. Kolmogorov's defence of Mendelism

In 1939 N.I. Ermolaeva published the results of an experiment which repeated parts of Mendel's classical experiments. On the basis of her experiment she concluded that Mendel's principle that self-pollination of hybrid plants gave rise to segregation proportions 3:1 was false. The great probability theorist A.N. Kolmogorov reviewed Ermolaeva's data using a test, now referred to as Kolmogorov's, or Kolmogorov-Smirnov, test, which he had proposed in 1933. He found, contrary to Ermolaeva, that her results clearly confirmed Mendel's principle. This paper shows that there were methodological flaws in Kolmogorov's statistical analysis and presents a substantially adjusted approach, which confirms his conclusions. Some historical commentary on the Lysenko-era background is given, to illuminate the relationship of the disciplines of genetics and statistics in the struggle against the prevailing politically-correct pseudoscience in the Soviet Union. There is a Brazilian connection through the person of Th. Dobzhansky.     

The variability of the mitochondrial genome in human aging: a key for life and death?

The impressive performance of the research in mitochondrial genetics and human aging in the last decade outlines a new scenery in which the inherited variation of the mitochondrial genome (mtDNA) may play a role in rate and quality of aging. This variation in humans was initially looked at as nearly neutral, and useful just for the reconstruction of human population history. However, recent data suggest that different mtDNA molecules are qualitatively different from each other. The aim of this paper is to discuss current ideas on the relationships among mitochondrial function, mtDNA inherited variation, and aging. The main processes where the mitochondrion is involved and the importance these processes have on aging and death of individuals will be described. A possible connection between programmed death phenomena (mitoptosis, apoptosis, phenoptosis) and rate and quality of aging will be discussed. Finally, the possible role played in these processes by the mtDNA germline variation will be explored.     

Time course of attention reveals different mechanisms for spatial and feature-based attention in area V4

Attention can facilitate visual processing, emphasizing specific locations and highlighting stimuli containing specific features. To dissociate the mechanisms of spatial and feature-based attention, we compared the time course of visually evoked responses under different attention conditions. We recorded from single neurons in area V4 during a delayed match-to-sample task that controlled both spatial and feature-based attention. Neuronal responses increased when spatial attention was directed toward the receptive field and were modulated by the identity of the target of feature-based attention. Modulation by spatial attention was weaker during the early portion of the visual response and stronger during the later portion of the response. In contrast, modulation by feature-based attention was relatively constant throughout the response. It appears that stimulus onset transients disrupt spatial attention, but not feature attention. We conclude that spatial attention reflects a combination of stimulus-driven and goal-driven processes, while feature-based attention is purely goal driven.     

Methods for long-term virus preservation

Viruses exhibit a wide variety of structural and chemical differences, but, in general, their infectivity may be destroyed by degradative enzymes that destroy nucleic acids, by detergents that solubilize the lipid-containing envelopes thus exposing the nucleic acid, by temperatures higher than about 50 degrees C, or by chemicals that breakdown capsid proteins. Preserving the viruses at low or ultra-low temperatures, and/or in the absence of water, slows down these destructive processes sufficiently to increase significantly the length of time that the virus can be stored as infectious material. Supplements such as serum are presumed to stabilize the environmental conditions and to block degradative processes. The methods by which viruses may be preserved for long periods of time are similar to those employed for other microorganisms and are relatively simple. Nevertheless, attention to detail, good laboratory practice, aseptic technique, meticulous recordkeeping, and regular monitoring of the stored materials will increase the success rate and reduce problems of contamination or loss in the storage containers, where many different viruses may be stored for posterity! This article describes some of the simplest and most reliable storage procedures for viruses, but the author recognizes that everyone will have a favorite method to suit his or her own particular virus.     

Macroecology of habitat choice in long-distance migratory birds

Patterns of habitat choice in ecological communities are not only influenced by present-day selective forces but also by historical processes, such as the biogeographical history of the lineages they are composed of. Nevertheless, it has been very difficult to test historical factors. The possible tropical origin of long-distance migratory birds provides an opportunity for such a test. If habitat choice of long-distance migrants is inherited from their tropical ancestors then Nearctic long-distance migrants might have acquired their habitat choice from Neotropical forest species and European long-distance migrants from African savannah species. Here we use a macroecological approach to show that this hypothesis can be confirmed. Long-distance migrants in the Nearctic are found in forested habitat types, while those in Europe are found in open ones. In comparison, the habitat choice of residents and short-distance migrants (in genera without long-distance migration) does not differ between the Nearctic and Europe. These results demonstrate that habitat choice in temperate bird communities can be explained by the tropical history of long-distance migrants. Thus, habitat choice seems to be shaped not only by local mechanisms, but also by processes acting on much larger spatial and temporal scales.     

Courtship Behavior and Detection of Female Receptivity in the Parasitoid Wasp Urolepis rufipes

Once a Urolepis rufipes male mounted, the female beat her antennae against his mouth and clypeus. Immediately after he swept his antennae rapidly downward and extruded his mouthparts, her abdomen rose as she opened her genital orifice. Almost simultaneously he backed up for copulation and she folded her antennae against her head. Neither her abdomen rising nor her antennal folding were essential to his backing up as determined from their timing and from experiments in which her abdomen was sealed or her antennae were removed. Females did not open their genital orifice if with a sealed-mouth male; and antennae-removed females did not open even in the few cases where untreated males extruded their mouthparts. Unlike a closely related species, females mounted by sealed-mouth males did not open in response to air from containers of mating pairs.     

Hereditary cancer: family history, diagnosis, molecular genetics, ecogenetics, and management strategies

The translation of knowledge about hereditary breast cancer and its improved control, as well as prevention through prophylactic surgery, has been significantly accelerated through the veritable explosive discoveries in molecular genetics inclusive of BRCA1 and BRCA2 germline mutations. Needed however, among the physician community, medical geneticists, and genetic counselors, is a raised level of knowledge about hereditary breast cancer syndromes. Particular attention needs to be given to their extant genotypic and phenotypic heterogeneity, their natural history, and foremost, the requirement of a sufficiently detailed family history, with knowledge as to how to interpret its significance so that hereditary cancer syndrome can be diagnosed, should it, in fact, exist in the particular family. Collectively, surveillance and management programs can then be developed for the patient and his or her high-risk relatives. We believe very firmly that this knowledge needs to be extended to the individual patient(s), first- and second-degree relatives so that they can benefit from this knowledge.     

A familial "balanced" 3;9 translocation with cryptic 8q insertion leading to deletion and duplication of 9p23 loci in siblings.

A child with phenotypic features of the 9p- syndrome, including metopic craniosynostosis, small ears, abdominal wall defect, and mental retardation, as well as hypopigmentation, was found to have a cytogenetically balanced 3;9 translocation, with breakpoints at 3p11 and 9p23, inherited from his phenotypically normal father. Molecular analysis showed heterozygous deletion of the TYRP (tyrosinase-related protein) locus, as well as loci D9S157, D9S274, D9S268, and D9S267, in the child but in neither parent. FISH analysis of the proband''s father indicated that loci deleted in his son, including TYRP, were present on neither the der(3) nor the der(9) translocation products but had been inserted into the long arm of chromosome 8. Therefore, the apparent deletion of these loci in the proband was the result of meiotic segregation of the father''s 3;9 translocation chromosomes together with his normal chromosome 8 (not bearing the insertion from 9p23). Neither the deletion of these 9p23 loci from the translocation chromosomes nor their insertion into 8q was detectable by standard chromosome banding techniques. The proband''s sister exhibited speech delay, mild facial dysmorphism, and renal malformation, and her karyotype was 46,XX. Molecular analysis showed that she had inherited normal chromosomes 3 and 9, as well as the chromosome 8 with the insertion of 9p23 material, from her father.(ABSTRACT TRUNCATED AT 250 WORDS)     

Alternative reality and art: the creative world of Walter Inglis Anderson

Both mental illness and creativity run in families. This observation suggests the possibility of genetic predisposition; in light of the known dynamic interrelationships among the environment, the personality, and the brain, however, it does not diminish the possibility of significant environmental influence on personal development. An examination of the biological, psychological, and social forces impacting the life of Walter Inglis Anderson (1903-1965), the South's most important artist, serves as a case in point. Anderson's upbringing, including his mother's determination that her sons become artists and her beliefs about the shamanistic role of artists in society, might have played a large part in establishing an unusual and indelible frame of reference in a family whose history insinuated the possibility of untoward outcomes.Walter Anderson's life as an artist--one who lived at times in an alternative reality--raises questions about how a different set of circumstances might have affected his mental state as well as his talent. This essay discusses some of the important relationships, events, and circumstances in Walter Anderson's life from a biopsychosocial perspective, with emphasis on psychodynamic implications of his illness and its questionable diagnosis as schizophrenia.