Variations in phenotype reflect the influence of environmental conditions during development on cellular functions, including that of the genome. The recent integration of epigenetics into developmental psychobiology illustrates the processes by which environmental conditions in early life structurally alter DNA, providing a physical basis for the influence of the perinatal environmental signals on phenotype over the life of the individual. This review focuses on the enduring effects of naturally occurring variations in maternal care on gene expression and phenotype to provide an example of environmentally driven plasticity at the level of the DNA, revealing the interdependence of gene and environmental in the regulation of phenotype.

Epigenetics and the biological definition of gene x environment interactions.

accademiche [38]. Ada [45]. Adrian [45]. African [56]. Age [39, 49, 61]. Al [23]. Al-Rawi [23]. Aldous [68]. Alex [15]. Allure [46]. America [60, 66]. American [49, 69, 61, 52]. ancienne [25]. Andreas [28]. Angela [42]. Animals [16]. Ann [26]. Anna [19, 47]. Annotated [46]. Annotations [28]. Anti [37]. Anti-Copernican [37]. Antibiotic [64]. Anxiety [51]. Apocalyptic [61]. Archaeology [26]. Ark [36]. Artisan [32]. Asylum [48]. Atri [54]. Audra [65]. Australia [41]. Authorship [15]. Axelle [29].

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A Complete Bibliography of Publications in Isis, 2000{2009

This review surveys the organization of the olfactory and gustatory systems in the imago and in the larva of Drosophila melanogaster, both at the sensory and the central level. Olfactory epithelia of the adult are located primarily on the third antennal segment (funiculus) and on the maxillary palps. About 200 basiconic (BS), 150 trichoid (TS) and 60 coeloconic sensilla (CS) cover the surface of the funiculus, and an additional 60 BS are located on the maxillary palps. Males possess about 30% more TS but 20% fewer BS than females. All these sensilla are multineuronal; they may be purely olfactory or multimodal with an olfactory component. Antennal and maxillary afferents converge onto approximately 35 glomeruli within the antennal lobe. These projections obey precise rules: individual fibers are glomerulus-specific, and different types of sensilla are associated with particular subsets of glomeruli. Possible functions of antennal glomeruli are discussed. In contrast to olfactory sensilla, gustatory sensilla of the imago are located at many sites, including the labellum, the pharynx, the legs, the wing margin and the female genitalia. Each of these sensory sites has its own central target. Taste sensilla are usually composed of one mechano-and three chemosensory neurons. Individual chemosensory neurons within a sensillum respond to distinct subsets of molecules and project into different central target regions. The chemosensory system of the larva is much simpler and consists essentially of three major sensillar complexes on the cephalic lobe, the dorsal, terminal and ventral organs, and a series of pharyngeal sensilla.

The Organization of the Chemosensory System in Drosophila Melanogaster: A Review

Embodiment. This construct and process are central to ecosocial theory and epidemiological inquiry. Recognising that we, as humans, are simultaneously social beings and biological organisms, the notion of “embodiment” advances three critical claims: (1) bodies tell stories about—and cannot be studied divorced from—the conditions of our existence; (2) bodies tell stories that often—but not always—match people’s stated accounts; and (3) bodies tell stories that people cannot or will not tell, either because they are unable, forbidden, or choose not to tell. Just as the proverbial “dead man’s bones” do in fact tell tales, via forensic pathology and historical anthropometry, so too do our living bodies tell stories about our lives, whether or not these are ever consciously expressed. This glossary sketches some key concepts, definitions, and hypotheses relevant for using the construct of “embodiment” in epidemiological research, so as to promote not only rigorous science but also social equity in health.

https://jech.bmj.com/content/jech/59/5/350.full.pdf

Embodiment: a conceptual glossary for epidemiology

While sequencing of the human genome surprised us with how many protein-coding genes there are, it did not fundamentally change our perspective on what a gene is. In contrast, the complex patterns of dispersed regulation and pervasive transcription uncovered by the ENCODE project, together with non-genic conservation and the abundance of noncoding RNA genes, have challenged the notion of the gene. To illustrate this, we review the evolution of operational definitions of a gene over the past century—from the abstract elements of heredity of Mendel and Morgan to the present-day ORFs enumerated in the sequence databanks. We then summarize the current ENCODE findings and provide a computational metaphor for the complexity. Finally, we propose a tentative update to the definition of a gene: A gene is a union of genomic sequences encoding a coherent set of potentially overlapping functional products. Our definition sidesteps the complexities of regulation and transcription by removing the former altogether from the definition and arguing that final, functional gene products (rather than intermediate transcripts) should be used to group together entities associated with a single gene. It also manifests how integral the concept of biological function is in defining genes.

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What is a gene, post-ENCODE? History and updated definition

Introduction Part I. Genes and Traits: 1. The dissolution of protein coding genes in molecular biology Thomas Fogle 2. The differential concept of the gene: past and present Sara Schwartz 3. Gene concepts and genetic concepts Fred Gifford Part II. Extracting The Units Of Heredity: 4. From measurement to organization: a philosophical scheme for the history of the concept of heredity Jean Gayon 5. From gene to genetic hierarchy: Richard Goldschmidt and the problem of the gene Michael R. Dietrich 6. Seymour Benzer and the definition of the gene Frederic L. Holmes Part III. Genetic Programs and Developmental Genes: 7. Decoding the genetic program Evelyn Fox Keller 8. Genes classical and developmental: the different use of genes in evolutionary synthesis Scott F. Gilbert 9. The developmental gene concept: history and limits Michel Morange Part IV. Conceptual Perspectives: 10. Gene concepts: fragments from the perspective of molecular biology Hans-Jorg Rheinberger 11. Reproduction and the reduction of genetics James R. Griesemer 12. A unified view of the gene, or how to overcome reductionism Peter J. Beurton The gene - a concept in tension: A critical overview Raphael Falk.

/pdf/the-concept-of-the-gene-in-development-and-evolution-4waunql2w1.pdf

The Concept of the Gene in Development and Evolution: Historical and Epistemological Perspectives

There are 36 to 42 taste bristles on each half of the labellum of Drosophila melanogaster; most of them are two-pronged with a pouch between them. Some end bluntly with a pore at the tip. Each taste-bristle has two lumina: one is circular, the other crescent-like in cross section. In most bristles four dendrites of chemoreceptor neurons run along the circular lumen. In five to seven taste-bristles only two chemoreceptor neurons are found. A mechanoreceptor neuron sends a dendrite to the base of each taste-bristle. The dendrites are surrounded by four concentrically-arranged sheath cells. The inner cell secretes the cuticular sheath; cells II and III are presumably two trichogens, one secreting the bristle material around the circular lumen, the other around the crescent-like lumen. Cell IV, especially rich in bundles of microtubules, secretes the cuticle of the socket, and corresponds to the tormogen. The neurons have the typical structure found in insect sensilla. In many sensilla one neuron is less electron-dense than the others and may be the water-sensor. On the medial side of the labellum between the pseudotracheae are rows of taste pegs covered by folds. In each peg one chemoreceptor and one mechanoreceptor are found. The number of axons in each labial nerve agrees with the total number of dendrites in all taste organs of each lobe.

Labellar taste organs of Drosophila melanogaster.

The Concept of the Gene in Development and Evolution

What is a gene

An allelism matrix of ethyl methanesulphonate-induced recessive lethals found in a short chromosomal segment covered by the Y· mal + chromosome was constructed. When allelism tests for the lethals were extended to X-ray-induced lethals, a consistent linear map of 34 functional units could be constructed. 80% of the chemically induced lethals comprised single sections, which supports the view that most ethyl methanesulphonate-induced lethals were point-mutations. Most X-ray-induced lethals that were multi-section lethals were aberrations. The distribution of mutations in the affteced units was highly non-random; consequently any pooling of sensitivity patterns for whole chromosome segments would be misleading. There were some “hot-spots”, possibly due to the vicinity of intercalary heterochromatin. There was also an excess of chromosomes with more than one lethal. The possibility that variation in specificity of lethal and visible mutations obtained with different mutagenic agents is a secondary function of the number of “essential sites” in “vital” and “non-vital” genes is discussed.

Raphael Falk

Papers

The Concept of the Gene in Development and Evolution: Historical and Epistemological Perspectives

Labellar taste organs of Drosophila melanogaster.

The Concept of the Gene in Development and Evolution

What is a gene

Fine structure analysis of a chromosome segment in Drosophila melanogaster analysis of ethyl methanesulphonate-induced lethals