Preparation and characterization of native lens cell cytoplasm

Clark, John I.; Delaye, M.; Hammer, Phyllis; Mengel, L.

doi:10.3109/02713688108998367

Cited by 20 publications

(7 citation statements)

References 11 publications

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“…These results are in agreement with previous data by Clark et al (1982), who reported an average cytoplasmic unit size of 12n5 nm using light-scattering spectroscopy. Although it is not possible to describe the structural units in detail based on the available images and analysis, it is reasonable to speculate that the structural features are derived from the wellcharacterized cytoplasmic crystallin monomers (with molecular masses 20-35 kD) and oligomers.…”

Section: Quantitative Analysis Of Areas In Designated Regions Under Tsupporting

confidence: 83%

Fourier Analysis of Textural Variations in Human Normal and Cataractous Lens Nuclear Fiber Cell Cytoplasm

Taylor

Costello

1999

Experimental Eye Research

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Section: Quantitative Analysis Of Areas In Designated Regions Under Tsupporting

confidence: 83%

Fourier Analysis of Textural Variations in Human Normal and Cataractous Lens Nuclear Fiber Cell Cytoplasm

Taylor

Costello

1999

Experimental Eye Research

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“…A temperaturedependent reversible opacification can be induced in the nucleus of these young lenses (24)(25)(26)(27)(28). This behavior appears to be an intrinsic property of the concentrated mixture of crystallins, since it also can be induced in purified, membranefree cytoplasmic extracts of lens nucleus (27,(29)(30)(31)(32). Cold cataract has been modeled as a reversible phase-separation phenomenon (26)(27)(28)(29)(30)(31)(32).…”

mentioning

confidence: 99%

“…This behavior appears to be an intrinsic property of the concentrated mixture of crystallins, since it also can be induced in purified, membranefree cytoplasmic extracts of lens nucleus (27,(29)(30)(31)(32). Cold cataract has been modeled as a reversible phase-separation phenomenon (26)(27)(28)(29)(30)(31)(32). Upon lowering the temperature below a critical value Tc, the cytoplasm separates into protein-rich and protein-poor domains.…”

mentioning

confidence: 99%

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Opacification of gamma-crystallin solutions from calf lens in relation to cold cataract formation.

Siezen¹,

Fisch²,

Slingsby³

et al. 1985

Proc. Natl. Acad. Sci. U.S.A.

113

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To determine the molecular mechanisms for cold cataract formation in the nucleus of the young mammalian lens, we have investigated the thermally reversible opacification of -crystallin solutions isolated from calf lens. Coexistence curves (plots of opacification temperature Tc versus protein concentration) were determined for the individual y-crystallin fractions II, III, and IV as well as for the unfractionated -crystallin mixtures isolated from the nucleus and cortex. The coexistence curve of yIV-crystallin is remarkably elevated above those of y4I-and yIII-crystallin and the -crystallin mixtures. The yIV-crystallin fraction is the major determinant of the opacification temperature within the whole lens or isolated cytoplasm. Quasielastic light-scattering spectroscopy of yIV-crystallin solutions indicates that above Tc there are two populations of protein aggregates of distinctly different mean size. As the temperature is lowered towards Tc, both populations increase in size. Opacification occurs when the population of large scatterers, which is composed of <0.1% protein by weight, reaches an average radius of about 20,000 A.The cytoplasm in eye lens cells contains a highly concentrated solution of lens-specific proteins, the crystallins. Their concentration increases from =250 to 400 g/liter going from cortex to nucleus, thus establishing the refractive index gradient required for proper focusing of incident light (1). The cytoplasm is normally transparent because of short-range ordering of the crystallins (2, 3). Mammalian lenses contain primarily a-crystallins (Mr 700,000-1,200,000), l3-crystallins (Mr 50,000-300,000) and -crystallins (Mr 20,000) (1,4,5). Their relative proportions vary with age and location within the lens as a result of both differential synthesis during development and selective degradation and insolubilization with aging (4-15). The lens nucleus is highly enriched in -crystallins, which are monomeric, basic proteins rich in sulfhydryl groups (8,(16)(17)(18)(19). The majority of human cataracts represent an irreversible opacification of the lens nucleus that progresses with age, a condition that is accompanied by oxidation of sulfhydryl groups, aggregation, and insolubilization of the various crystallins (4,8,13,(20)(21)(22)(23).The cold cataract phenomenon observed in most young mammalian lenses (e.g., calf, rat, and rabbit) is a convenient model system to study the relationship between nuclear opacification and -crystallin aggregation. A temperaturedependent reversible opacification can be induced in the nucleus of these young lenses (24)(25)(26)(27)(28). This behavior appears to be an intrinsic property of the concentrated mixture of crystallins, since it also can be induced in purified, membranefree cytoplasmic extracts of lens nucleus (27,(29)(30)(31)(32). Cold cataract has been modeled as a reversible phase-separation phenomenon (26)(27)(28)(29)(30)(31)(32). Upon lowering the temperature below a critical value Tc, the cytoplasm separates into protein-rich and protein-poor d...

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“…The protocol and the biochemical assays to check the nondenaturation of the proteins are reported in detail in Ref. 23. The physical properties (transparency, viscosity, light scattering) of this isolated material are similar to that of the native cytoplasm.z3~z4…”

Section: Preparation Of the Samplementioning

confidence: 99%

Mutual diffusion of crystallin proteins at finite concentrations: A light‐scattering study

Delaye

Gromiec

1983

Biopolymers

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SynopsisBoth static and quasielastic light-scattering measurements were performed on solutions of crystallin proteins extracted from calf lens cortex. The concentration range between ideal (c -0) and physiologic solutions (c up to 50%, w/w) was investigated. The intensity data are compatible with a model where the globular crystallins behave as "hard spheres," the radius of which does not depend on concentration. The correlation function of the scattered intensity is correctly described by a single exponential (mutual diffusion) for 0 < c < 5%. For larger concentrations, a slowly relaxing component, whose amplitude increases with c, appears on top of the rapid component describing the mutual diffusion. Heterodyne detection is used to uncouple these two components. The mutual diffusion coefficient is then found to decrease linearly up to c N 10% and to deviate sharply from linearity at larger concentrations.

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Preparation and characterization of native lens cell cytoplasm

Cited by 20 publications

References 11 publications

Fourier Analysis of Textural Variations in Human Normal and Cataractous Lens Nuclear Fiber Cell Cytoplasm

Fourier Analysis of Textural Variations in Human Normal and Cataractous Lens Nuclear Fiber Cell Cytoplasm

Opacification of gamma-crystallin solutions from calf lens in relation to cold cataract formation.

Mutual diffusion of crystallin proteins at finite concentrations: A light‐scattering study

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