Expressivity

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Expressivity

 

the phenotypic manifestation of genes. Some genes in animals, plants, and microorganisms are characterized by comparatively constant expressivity; that is, they are manifested more or less equally in all the individuals of the corresponding genotype. For example, all wheat plants homozygous for the gene responsible for the absence of awns develop awnless spikes. Other genes—apparently the majority—are distinguished by changing expressivity. Rabbits and some other animals are known to have a Himalayan-pigmentation gene, which is responsible for black feet, ear, nose, and tail tips against a white or some other light background. However, such coloring appears only when young animals of the Himalayan breed are raised in environments having moderate temperatures. The for of individuals of the same Himalayan genotype becomes entirely white in high temperatures and black in low. This example shows that expressivity is influenced by environmental factors—in this case, the temperature.

Under identical environmental conditions, the expressivity of a gene may depend on the genotypic environment, that is, on the other genes with which the given gene combines to form the genotype. The possibility that stabilizing artificial selection can sometimes affect the extent to which hereditary traits are manifested in the phenotype suggests that modifier genes are involved in the variation of expressivity. Expressivity and penetrance, the principal interrelated indicators of phenotypic variability of gene manifestation, are widely used in phenogenetics, medical genetics, and breeding of animals, plants, and microorganisms.

REFERENCES

Lobashev, M. E. Genetika. Leningrad, 1967.
Timofeev-Resovskii, N. V., and V. I. Ivanov. “Nekotorye voprosy fenogenetiki.” In the collection Aktual’nye voprosy sovremennoi genetiki. Moscow, 1966.

V. I. IVANOV

References in classic literature ?
For him, indeed, human life is, in the first instance, only an additional, and as it were incidental grace, upon this expressive landscape.
On the contrary, when Kitty looked at him in society, as one sometimes looks at those one loves, trying to see him as if he were a stranger, so as to catch the impression he must make on others, she saw with a panic even of jealous fear that he was far indeed from being a pitiable figure, that he was very attractive with his fine breeding, his rather old-fashioned, reserved courtesy with women, his powerful figure, and striking, as she thought, and expressive face.
Her brow was clear and ample, her blue eyes cloudless, and her lips and the moulding of her face so expressive of sensibility and sweetness that none could behold her without looking on her as of a distinct species, a being heaven-sent, and bearing a celestial stamp in all her features.
Not so the mother, she threw herself on the earth, and receiving the cold and ghastly head into her lap, she sat contemplating those muscular features, on which the death-agony was still horridly impressed, in a silence far more expressive than any language of lamentation could have proved.
At times her fingers played in the matted hair of the dead, and at others they lightly attempted to smooth the painfully expressive muscles of its ghastly visage, as the hand of the mother is seen lingering fondly about the features of her sleeping child.
Affery, woman,' said Mr Flintwinch, with a friendly grin on his expressive countenance, 'if you ever have a dream of this sort again, it'll be a sign of your being in want of physic.
But, his popular name was Rumty, which in a moment of inspiration had been bestowed upon him by a gentleman of convivial habits connected with the drug-markets, as the beginning of a social chorus, his leading part in the execution of which had led this gentleman to the Temple of Fame, and of which the whole expressive burden ran:
With those submissive words, the dutiful wife preceded him down a few stairs to a little basement front room, half kitchen, half parlour, where a girl of about nineteen, with an exceedingly pretty figure and face, but with an impatient and petulant expression both in her face and in her shoulders (which in her sex and at her age are very expressive of discontent), sat playing draughts with a younger girl, who was the youngest of the House of Wilfer.
Over that again were a pair of flags; beneath the last button of his coat were a couple of cannon; and the whole formed an expressive and undoubted likeness of the Marquis of Granby of glorious memory.
The little man accompanied these latter words with a wink, expressive of the estimate he had formed of the travellers' finances.
The sources of this expressivity are manifold: the music itself, its structure, orchestration, personal associations, social settings, but also and very importantly the act of performance, the interpretation and expressive intentions made explicit by the musicians through nuances in timing, dynamics etc.
Attunement in Expressive Arts Therapy: Toward an Understanding of Embodied Empathy" by Mitchell Kossak (Associate Professor, Expressive Therapies Department, Lesley University, Cambridge, Massachusetts) is a 184 page compendium comprised of six major chapters: Contexts of Attunement in the Arts and Therapy; Tuning in the embodied Creative Intelligence; Attunement and Improvisation: Embracing the Unknown, Rehearsals for Life; Rhythm and Resonance: Deep Connections to Self, Other and University Consciousness; Tuning In.