Poultry Science 1994;
Use of this material approved
Poultry Science Association, ©1994
Influence of Manganese Deficiency
on the Characteristics of Proteoglycans of Avian Epiphyseal
Growth Plate Cartilage
A. C.-H. LIU, B. S. HEINRICHS, and R. M. LEACH, JR.
The need for manganese for normal skeletal development
appears to be related to its role in proteoglycan biosynthesis.
The purpose of this research was to characterize the proteoglycans
synthesized under conditions of manganese deficiency.
The proteoglycans were extracted from epiphyseal growth
plate cartilage and the monomers separated by cesium chloride
density gradient centrifugation followed by column chromatography.
The proteoglycan monomers from normal cartilage contained
primarily (92%) chondroitin sulfate side chains with keratan
sulfate being a minor (8%) component. Manganese deficiency
reduced the total amount of cartilage proteoglycans. Of
the monomers present in deficient cartilage, the majority
(75%) were similar to those found in normal cartilage.
Cartilage from deficient chicks also contained a second
monomer fraction (25%) characterized by a reduced carbohydrate
content. Thus, in addition to a reduction in total proteoglycan
content, manganese deficiency results in qualitative changes
in the proteoglycans present in epiphyseal growth plate
Manganese has been demonstrated to be an essential
element for many species of animals and is presumed to
be essential for humans. If manganese deficiency occurs
during fetal development or early postnatal life, severe
impairment of skeletal development can occur (Leach, 1988).
The primary effect is decreased endochondral bone growth,
resulting in chondrodystrophy (dwarfism). The role of
manganese in normal epiphyseal cartilage metabolism appears
to be centered around its involve-ment in the biosynthesis
of proteoglycans, which are major constituents of cartilage
extracellular matrix (Leach, 1986). Proteoglycans occur
in the extracellular matrix as complex aggregates containing
proteoglycan monomers, hyaluronic acid, and link proteins
(Hascall, 1988). The proteoglycan monomer is comprised
of a protein core with a large number of glycosaminoglycan
side chains. Manganese is a co-factor for glycosyltransferases,
enzymes involved in the synthesis of the glycosaminoglycan
side chains (Leach, 1986).
The purpose of this research was to determine the characteristics
of the proteoglycans isolated from manganese deficient
cartilage. The research addressed the question: Is there
a reduced number of normal proteoglycan molecules or are
abnormal proteoglycan molecules produced under conditions
of manganese deficiency?
In conclusion, the proteoglycans of normal
epiphyseal growth plate cartilage that were isolated using
CsCl density gradient centrifugation were characterized
by large amounts (92%) of chondroitin sulfate side chains
and a smaller amount (8%) of keratan sulfate side chains.
Manganese deficiency substantially reduced the total proteoglycan
content. Of the proteoglycan monomers that were present,
the majority (75%) were similar to those found in normal
cartilage. However, a second monomer fraction (25%) was
found to be reduced in carbohydrate content, suggesting
the presence of either smaller side chains or fewer side
chains per molecule of core protein.
Hascall, V.C., 1988. Proteoglycans:
The chondroitin sulfate/keratin sulfate proteoglycan
of cartilage. Pages 189-198 in: Institute for Scientific
Information Atlas of Science, BioChemistry. Vol. 1.
Institute for Scientific Information, Philadelphia, PA.
Leach, R.M., Jr., 1986. Mn(II) and
glycosyltransferases essential for skeletal development.
Pages 81-91 in: Manganese in Metabolism and Enzyme Function.
B.L. Schramm, and F.W Wedler, ed. Academic Press,
New York, NY.
Leach, R.M. Jr., 1988. The role of
trace elements in the development of cartilage matrix.
Pages 267-271 in. Trace Elements in Man and Animals
6. L. Hurley, C.L. Keen, B. Lonnerdal, and R.B. Rucker,
ed. Plenum Publishing Corp., New York, NY.