نتایج جستجو برای: epigenesis
تعداد نتایج: 174 فیلتر نتایج به سال:
What is Volvox? The name comes from the Latin volvere, to roll, and ox, as in atrox, fierce. Volvox is a spherical multicellular green alga, which contains many small biflagellate somatic cells and a few large, non-motile reproductive cells called gonidia, and swims with a characteristic rolling motion. Ever since van Leeuwenhoek first viewed these algal ‘fierce rollers’ with utter fascination ...
Vision and manipulation are inextricably intertwined in the primate brain. Tantalizing results from neuroscience are shedding light on the mixed motor and sensory representations used by the brain during reaching, grasping, and object recognition. We now know a great deal about what happens in the brain during these activities, but not necessarily why. Is the integration we see functionally imp...
Most bilaterians specify primordial germ cells (PGCs) during early embryogenesis using either inherited cytoplasmic germ line determinants (preformation) or induction of germ cell fate through signaling pathways (epigenesis). However, data from nonbilaterian animals suggest that ancestral metazoans may have specified germ cells very differently from most extant bilaterians. Cnidarians and spong...
This article reviews the concept of Lamarckian inheritance and the use of the term epigenetics in the field of animal genetics. Epigenetics was first coined by Conrad Hal Waddington (1905-1975), who derived the term from the Aristotelian word epigenesis. There exists some controversy around the word epigenetics and its broad definition. It includes any modification of the expression of genes du...
Cross-sectional studies have reported an association between lead (Pb) levels in bone and delinquent behavior in later childhood and adolescence. This is the first prospective longitudinal study of Pb and child development to address this question with comprehensive assessments of toxicant exposure and other developmental cofactors. A prospective longitudinal birth cohort of 195 urban, inner-ci...
plants and animals. 'Evolution' should not be understood in the modem sense because an assumption of evolution included the idea of pre-delineation, ie. that all that was going to evolve had already an invisible existence in the beginning. Wolff comes down on the side of epigenesis, maintaining that new entities can be generated and, indeed, new forms come into being, without any previous exist...
In this study, clay and non-clay minerals in the cement of Cretaceous volcanogenic–sedimentary rocks from bottom marginal seas north-western Pacific Ocean adjacent areas were studied. Corrensite mixed-layer chlorite–smectite, rectorite illite–smectite, chlorite, swelling chlorite (?), illite, kaolinite, smectite calcite, ankerite, barite, gypsum, epsomite, zeolites (laumontite, analcime, stilbi...
For much of the 20th century scientific psychology treated the relative contributions of nature and nurture to the development of phenotypes as the result of two quite separate sources of influence. One, nature, was linked to biological perspectives, often manifest as "instinct", while the other, nurture, was taken to reflect psychological influences. We argue that this separation was contingen...
This paper assesses the current status of Piaget s theory of sensorimotor intelli gence in relation to three persistent issues about the abilities of human infants the nature of initial mechanisms the traditional view that re presentational functioning is the outcome of infant development and the place of general purpose developmental processes Varela s view of three successive paradigms for co...
Most contemporary accounts of psychopathology acknowledge the importance of both biological and environmental influences on behavior. In developmental psychopathology, multiple etiological mechanisms for psychiatric disturbance are well recognized, including those operating at genetic, neurobiological, and environmental levels of analysis. However, neuroscientific principles are rarely consider...
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