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1. Neurofilament complement was studied in an early chordate (Ciona intestinalis) and six fish species by immunoblot with antisera specific for each of the three mammalian NF subunits. 2. The anti-NF-H and anti-NF-M antisera were characterized as strictly specific for phosphorylated epitopes located in the carboxyterminal domain. 3. The NF-L subunit is absent in primitive chordates and appears first in fish; it can be identified on the basis of its apparent mol. wt, its reactivity with the anti-IFA antibody and with polyclonal antibodies raised to the NF-L subunit of mammals. 4. Primitive chordate neurofilaments are constituted by a single polypeptide of ca 160,000 mol. wt exhibiting only M-type phosphorylation-dependent epitopes. 5. Primitive fish (Acipenser transmontanus, Salmo gairdneri, Scorpaena porcus, Serranus scriba) possess only a single high mol. wt NF subunit reacting with both anti-NF-H and anti-NF-M antiserum while more recent species (Mugil saliens, Perca fluviatilis) possess two high mol. wt NF subunits which are immunologically distinct as to their phosphorylation structures. 6. The existence in some fish species of two high mol. wt NF polypeptides suggests that the process of gene duplication and diversification supposed to have given rise to the two high mol. wt NF subunits of mammals and birds has occurred repeatedly in vertebrate evolution, and may be regarded as a case of convergent evolution.
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Man's mental functions have developed unevenly. Sometime during the last millennium the muscle man was superseded by the intelligent man. The human psyche, besides intellectual capacity, includes a basic function that can be called emotional capacity. This function can be studied using the same approach as in the study of intellectual capacity. The two functions are considered to be partly independent of each other. Emotional capacity depends on the individual's genetic emotional make-up (emotional genotype) and how this inherited set of qualities has been conditioned by environmental factors (emotional phenotype). Man's emotional capacity is very little differentiated: emotionally, modern man still functions almost like Stone Age man. Intellectual capacity, however, has undergone enormous development. As emotional capacity to a large extent governs man's behaviour and intellectual capacity is the instrument he uses to reach his goals, the uneven differentiation of the mental functions may have consequences that are unfavourable to the survival of our species.
We have determined the complete nucleotide sequence of the mouse gene encoding the neurofilament NF-H protein. The C-terminal domain of NF-H is very rich in charged amino acids (aa) and contains a 3-aa sequence, Lys-Ser-Pro, that is repeated 51 times within a stretch of 368 aa. The location of this serine-rich repeat in the phosphorylated domain of NF-H indicates that it represents the major protein kinase recognition site. The nfh gene shares two common intron positions with the nfl and nfm genes, but has an additional intron that occurs at a location equivalent to one of the introns in non-neuronal intermediate filament-coding genes. This additional nfh intron may have been acquired via duplication of a primordial intermediate filament gene.
Behavioral tests of hearing and sound localization in the North American pocket gopher (Geomys bursarius) show that it is unique among mammals. It has a severely attenuated range of hearing and only rudimentary ability to localize sound. In these respects, the hearing of gophers can be properly termed 'vestigial' and suggests that life underground can produce as severe a change in hearing as a light-less world produces in vision or an odorless world produces in olfaction.
rab3A, a low molecular weight GTP-binding protein of synaptic vesicles with a putative function in synaptic vesicle docking, interacts in a GTP-dependent manner with rabphilin-3A, a peripheral membrane protein that binds Ca2+ and phospholipids. We now show that rabphilin-3A is an evolutionarily conserved synaptic vesicle protein that is attached to synaptic vesicle membranes via its N terminus and exhibits a heterogeneous distribution among synapses. In rab3A-deficient mice, rabphilin-3A is decreased in synapses belonging to neurons that primarily express rab3A and accumulates in the perikarya of these neurons. In contrast, neurons expressing significant levels of rab3C still contain normal levels of rabphilin-3A in a synaptic pattern, and rabphilin-3A binds rab3C in vitro. These results suggest that analogous to the membrane recruitment of raf by ras, rab3A and rab3C may function in recruiting rabphilin-3A to the synaptic vesicle membrane in a GTP-dependent manner.
A novel homeobox-containing gene has been identified. Its name, Orthopedia (Otp), exemplifies the homology shared by both the orthodenticle and Antennapedia homeodomains. Otp is highly conserved in evolution. In mouse, Otp is expressed only in restricted domains of the developing forebrain, hindbrain, and spinal cord. In Drosophila, otp first appears at gastrulation in the ectodermal proctodeum and later in the hindgut, anal plate, and along the CNS. Here, we compare the Otp-, Distal-less homeobox 1-(DIx1-), Orthodenticle homolog 1-(Otx1-), Otx2-, and Empty spiracles homolog 2-expressing domains. Our results indicate that Otp is expressed along the CNS both in mouse and Drosophila; Otp could specify regional identities in the development of the forebrain and spinal cord; transcription of Otp and DIx1 takes place in alternating hypothalamic regions reminiscent of a segment-like pattern; and the structural and functional conservation could correspond to a conserved function maintained in evolution.
The highly complex eyes of vertebrates, insects and molluscs have long been considered to be of independent evolutionary origin. Recently, however, Pax-6, a highly conserved transcription factor, has been identified as a key regulator of eye development in both mammals and flies. Homologues of Pax-6 have also been identified in species from other phyla, including molluscs. The wide variety of eyes in the animal kingdom may, therefore, have evolved from a single ancestral photosensitive origin.
Strong and increasing evidence shows that nitric oxide (NO) contributes to immune function, and in particular to 'non-specific host defense'. The aim of the present review was to focus the current understanding of the role of NO as a biochemical effector of L-arginine-dependent cell-mediated immune responses to neoplastic cells in vitro and in vivo. The cytokine-inducible nitric oxide synthase (NOS) seems to mainly be implicated in the cytotoxic activity of almost all the effector cells involved in tumor cell killing. The cytotoxic actions of NO against tumor cells appear to be related mainly to inhibition of several heme-containing enzymes of the mitochondrial electron transport complex and the citric acid cycle.
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Against a background of recent progress in developmental neuroscience, some of which has been taken as challenging to the modularity hypothesis of , this article contrasts two competing conceptions of modularity: sui generis modularity, according to which modules are treated as independent neurocognitive entities that owe nothing to one another, and descent-with-modification modularity, according to which current cognitive modules are understood to be shaped by evolutionary changes from ancestral cognitive modules. I argue that sui generis modularity is incompatible with a range of data, from the co-occurrence of deficits to the patterns of activation in neuroimaging studies, but that same range of data is compatible with descent-with-modification modularity. Furthermore, I argue that the latter conception of modularity may have important implications for the practice and conception of fields such as developmental disorders and linguistics.
The significance of Behaviourism is examined in relation to its far conceptual roots, i.e. comparative animal studies initiated by Darwin, mechanistic physiological thinking initiated by Descartes and empiricist associationism. The Behaviourist anti-mentalist position induced neuromechanistic interpretations based on Pavlovian reflexes, stimulus-response connectionism and the very first hypotheses on synaptic plasticity. As a result, the evolutionary tradition was dropped and the two other trends were combined into a new adaptive version of Cartesian automaton, with persisting influences in modern reductionist thinking, from robotics and cognitive science to the neuroscience of learning and memory.
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Understanding how genes influence behavior, including sexuality, is one of biology's greatest challenges. Much of the recent progress in understanding how single genes can influence behavior has come from the study of innate behaviors in the fruit fly Drosophila melanogaster. In particular, the elaborate courtship ritual performed by the male fly has provided remarkable insights into how the neural circuitry underlying sexual behavior--which is largely innate in flies--is built into the nervous system during development, and how this circuitry functions in the adult. In this review we will discuss how genes of the sex determination pathway in Drosophila orchestrate the developmental events necessary for sex-specific behaviors and physiology, and the broader lessons this can teach us about the mechanisms underlying the development of sex-specific neural circuitry.
BACKGROUND: Chocolate consumption has long been associated with enjoyment and pleasure. Popular claims confer on chocolate the properties of being a stimulant, relaxant, euphoriant, aphrodisiac, tonic and antidepressant. The last claim stimulated this review. METHOD: We review chocolate's properties and the principal hypotheses addressing its claimed mood altering propensities. We distinguish between food craving and emotional eating, consider their psycho-physiological underpinnings, and examine the likely 'positioning' of any effect of chocolate to each concept. RESULTS: Chocolate can provide its own hedonistic reward by satisfying cravings but, when consumed as a comfort eating or emotional eating strategy, is more likely to be associated with prolongation rather than cessation of a dysphoric mood. LIMITATIONS: This review focuses primarily on clarifying the possibility that, for some people, chocolate consumption may act as an antidepressant self-medication strategy and the processes by which this may occur. CONCLUSIONS: Any mood benefits of chocolate consumption are ephemeral.