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Results for “IMPRINTING (PSYCHOLOGY)”

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PubMed1992

Sources of behavioral deviation modeled by early color preferences in quail. II. Diathetic genes and the leftover variance "V(e)".

The sources of deviation from population-typical norms of variability were studied in relation to early approach preferences between colors in newly hatched Japanese quail chicks (Coturnix coturnix japonica). Subjects were drawn from an unselected genetic control line, two genetic lines that were artificially selected for extreme blue and red preferences, their hybrids, and a large set of backcross and assortatively derived generations. Large progressive increases were observed with selection in the leftover (V(e)) component of F1 variance and consistent additional variance increases in F2 hybrids. Backcross generations exhibited greater than expected expression of the blue and red preference genes. Discussion differentiates between diathetic and normative influences in preference deviations and relates the increased Ve to relaxed normative canalization of preference development by directional selection.

Animals↗
PubMed1987

Dissimilar effects of L and D amino acids on the growth of Tetrahymena.

Of the L and D configurations of four amino acids (phenylalanine, valine, tryptophan, tyrosine) tested for influence on the growth rate of Tetrahymena, only L-tyrosine was able to induce imprinting in Tetrahymena pyriformis Zeuthen. D-valine stimulated the division of T. pyriformis NT-1, but failed to induce imprinting. The experiments have substantiated the selectivity of the amino acid receptors of T. pyriformis, and the extraordinary imprinting potential of tyrosine as well, as judged by its influence on the growth rate.

Amino Acids↗
PubMed1985

Study of the effect of estradiol on gonadotrophin levels in untreated male-to-female transsexuals.

This project was an attempt to test Dörner's theory that aspects of gender identity and sexual behavior depend on a defect in a normal imprinting mechanism of testicular testosterone (T) on the male hypothalamus. It has been suggested that such an action by T is incomplete in male-to-female transsexuals and that in this disorder the hypothalamus retains a cyclic pattern of gonadotrophin secretion and a positive feedback response to estrogens, such as is seen in the normal female. Five untreated male-to-female transsexuals and five normal male controls were each given 2 mg IM of estradiol, and T, estradiol, LH, and FSH globulin was measured serially over the following five days. No significant differences were found in the gonadotrophin or any of the other hormone responses in the transsexuals compared to normal controls. If there is a defect in imprinting of the hypothalamus in transsexual men, it does not seem to affect the basal levels of gonadotrophins or the pattern of their response to estrogen, at least in the intact male.

Adult↗
PubMed1991

Biological aspects of cytosine methylation in eukaryotic cells.

The existence in eukaryotes of a fifth base, 5-methylcytosine, and of tissue-specific methylation patterns have been known for many years, but except for a general association with inactive genes and chromatin the exact function of this DNA modification has remained elusive. The different hypotheses regarding the role of DNA methylation in regulation of gene expression, chromatin structure, development, and diseases, including cancer are summarized, and the experimental evidence for them is discussed. Structural and functional properties of the eukaryotic DNA cytosine methyltransferase are also reviewed.

Animals↗
PubMed1985

Imprinting of the Peking duck (Anas platyrhynchos) and dependence on exposure to light during ontogenesis.

Embryos of Peking ducks were either incubated in complete darkness up t o hatching or were put into light one week before hatching. Control embryos were incubated under dim light conditions which corresponded broadly to the natural conditions. Under standardized imprinting conditions the controls and both groups of the light deprived ducklings showed the 'following response'. Most of the dark-incubated embryos, however, did not distinguish between imprinting and test objects of different shapes. Since most of the embryos kept in darkness only for 21 days also failed to develop the capacity for shape discrimination, there is apparently a critical period for light influences on the development of this capacity at some time during the early prenatal period.

Animals↗
PubMed2005

The return of the whole organism.

The long trend towards analysis at lower and lower levels is starting to reverse. The new integrative studies must make use of the resources uncovered by molecular biology but should also use the characteristics of whole organisms to measure the outcomes of developmental processes. Two examples are given of how movement between levels of analysis is being used with increasing power and promise. The first is the study of behavioural imprinting in birds where many of the molecular and neural mechanisms involved have been uncovered and are now being integrated to explain the behaviour of the whole animal. The second is the triggering during sensitive periods in early life by environmental events of one of several alternative modes of development leading to different phenotypes. A renewed focus on the whole organism is also starting to change the face of evolutionary biology. The decision-making and adaptability of the organism is recognized an important driver of evolution and is increasingly seen as an alternative to the gene-focused views.

Adaptation, Physiological↗
PubMedDate not supplied

The molecular neurobiology of early learning, development, and sensitive periods, with emphasis on the avian brain.

The subcellular processes that correlate with early learning and memory formation in the chick and sensitive periods for this learning are discussed. Imprinting and passive avoidance learning are followed by a number of cellular processes, each of which persists for a characteristic time in certain brain regions, and may culminate in synaptic structure modification. In the chick brain, the NMDA subtype of glutamate receptor appears to play an important role in both memory formation and sensitive periods during development, similar to its demonstrated role in neural plasticity in the mammalian brain. Two important findings have emerged from the studies using chickens. First, memory formation appears to occur at multiple sites in the forebrain and, most importantly, it appears to "flow" from one site to another, leaving neurochemical traces in each as it moves on. Second, the memory is laid down either in different sites or in different subcellular events in the left and right forebrain hemispheres. Hence, we are alerted to the possibility of similar asymmetrical processes occurring in memory consolidation in the mammalian brain. The similarities between early memory formation and experience-dependent plasticity of the brain during development are discussed.

Animals↗
PubMed1998

X chromosome inactivation and the Xist gene.

Recent years have seen rapid progress towards understanding the molecular mechanisms involved in X chromosome inactivation (X inactivation). This progress has largely revolved around the discovery of the X inactive specific transcript (Xist) gene, which is known now to represent the master switch locus regulating X inactivation. In adult cells Xist is transcribed exclusively from the inactive X chromosome. The transcript has no apparent protein-coding potential and is retained in the nucleus in close association with the domain occupied by the inactive X chromosome. It is thus thought to represent a functional RNA molecule which acts as the primary signal responsible for the propagation of X inactivation. Developmental regulation of Xist correlates with the developmental timing of X inactivation. Recent results have demonstrated that Xist is both necessary and sufficient for X inactivation. Goals for the future are to understand the mechanism of Xist regulation which underlies the establishment of appropriate X inactivation patterns and to determine how Xist RNA participates in the process of propagating inactivation in cis.

Animals↗
PubMed2004

Hemispheric differences in the recognition of partly occluded objects by newly hatched domestic chicks (Gallus gallus).

Domestic chicks are capable of perceiving as a whole objects partly concealed by occluders ("amodal completion"). In previous studies chicks were imprinted on a certain configuration and at test they were required to choose between two alternative versions of it. Using the same paradigm we now investigated the presence of hemispheric differences in amodal completion by testing newborn chicks with one eye temporarily patched. Separate groups of newly hatched chicks were imprinted binocularly: (1) on a square partly occluded by a superimposed bar, (2) on a whole or (3) on an amputated version of the square. At test, in monocular conditions, each chick was presented with a free choice between a complete and an amputated square. In the crucial condition 1, chicks tested with only their left eye in use chose the complete square (like binocular chicks would do); right-eyed chicks, in contrast, tended to choose the amputated square. Similar results were obtained in another group of chicks imprinted binocularly onto a cross (either occluded or amputated in its central part) and required to choose between a complete or an amputated cross. Left-eyed and binocular chicks chose the complete cross, whereas right-eyed chicks did not choose the amputated cross significantly more often. These findings suggest that neural structures fed by the left eye (mainly located in the right hemisphere) are, in the chick, more inclined to a "global" analysis of visual scenes, whereas those fed by the right eye seem to be more inclined to a "featural" analysis of visual scenes.

Animals↗