Abstract
Sialic acids such as Nβacetylneuraminic acid have been found at the surfaces of various cells. They may play an important role in intercellular adhesion and hence in animal morphogenesis. This work demonstrates sialic acid at the surfaces of sevenβday chick embryo neural retinal cells and its regeneration after enzymatic removal.
Neural retinas were excised and dissociated with trypsin. The cells were
incubated in a solution of Vibrio cholerae neuraminidase. The enzymatic treat
ment released sialic acid which was assayed by thg thiobarbituric acid method
of Warren. The enzymatic treatment also reduced the cellular electrophoretic
mobility from 1.1 to 0.4 Γ 10^β4^ cm/sec/volt/cm measured in 0.067 molar phos
phate buffer at pH 7.5.
Cells which had been treated with neuraminidase were cultured in a modified
Eagle's minimum essential medium for up to 24 hours. During the period of
culture, the replacement of surface material was observed in two ways. First
was the progressive return of electrophoretic mobility to the preβneuraminidase
level. Second was the progressive return of sialic acid at the cell surface to the
original level. The latter was shown by second neuraminidase treatments and
determinations of sialic acid released.
Effects of neuraminidase upon the reaggregation of cells cultured on a
gyratory shaker in Eagle's medium were investigated. Neuraminidase was not
effective for dissociation of neural retina.