Synthesis of glycolipids and phospholipids in hamster cells: Dependence on cell density and the cell cycle

Hirschberg, Carlos B.; Wolf, B.; Robbins, Phillips W.

doi:10.1002/jcp.1040850105

Cited by 13 publications

(4 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Only 20% of these cells had reattached to the plate 4 h after removal of the buffer and resuspension in growth medium; in contrast, cells that had been trypsinized, centrifuged, and resuspended in growth medium without a 1-h incubation with buffer, showed 80% attachment at the same time. After 24 h, these cells had tripled in number (consistent with a doubling time of approximately 16 h (Hirschberg et al, 1975) , while the EDTA-treated cells had increased by only 20%. Numerous cell fragments could be observed under microscopic examination of these preparations.…”

Section: Resultsmentioning

confidence: 63%

“…Previous studies have shown that in the lcl clone of NIL cells (a line of hamster fibroblasts) the sialic acid containing glycolipid "hematoside", the principal glycolipid of this cell line, increases twoto threefold in amount when sparse cells become confluent (Sakiyama et al, 1972;Hirschberg et al, 1975). Since such an increase could be related to the presence of 7 From the Department of Biochemistry, St. Louis University School of Medicine, St. Louis, Missouri 63104.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Sialic acid uptake by fibroblasts

Hirschberg¹,

Goodman²,

Green³

1976

Biochemistry

View full text Add to dashboard Cite

The existence of surface sialytransferases that use cytidine monophosphate (CMP)-sialic acid as substrate has been postulated in previous studies. This is based on the assumption that if whole, viable cells can catalyze the transfer of sialic acid from CMP-sialic acid to endogenous acceptors, then the transferases carrying out the reaction must be on the cell surface, provided that (1) CMP-sialic acid does not enter the cells, and (2) CMP-sialic acid does not break down outside the cells, yielding free sialic acid which then may enter the cells, in amounts large enough to explain the incorporation. We now report evidence showing that after incubation of intact NIL, BHK, and 3T3 fibroblasts with CMP-sialic acid, at least 78% of the sialic acid incorporated by these cells is the result of free sialic acid uptake. When cells growing in a monolayer were incubated with a mixture of CMP-[14C]sialic acid and [3H]CMP-sialic acid with a ratio of 3H/14C=0.60, this ratio was found to be markedly increased in whole cells. Chemical analyses of the radioactive species in the incubation medium showed that a considerable portion of the radiolabeled sugar nucleotide had broken down to cytidine, phosphoric acid, and sialic acid. Upon incubation of cells with doubly labeled sugar nucleotide in the presence of a large excess of both nonradiolabeled cytidine and sialic acid, the cells incorporated less than 6% of both isotopes. Incubation of cells with a mixture of CMP-[14C]sialic acid and [3H]sialic acid resulted in only 20-40% of the radioactivity within the cells being membrane bound, and 70-90% of this incorporation could be inhibited by the addition of 10 mM azide to the incubation medium. The possibility that a small fraction of the total incorporation of sialic acid by these cells is due to surface sialytransferases cannot be completely ruled out. The uptake of free sialic acid by these fibroblasts is concentration dependent and a portion of it is incorporated into glycoproteins and glycolipids. Considerable loss of cell integrity was observed when fibroblasts grown on plates were removed by (ethylenedinitrilo)-tetraacetic acid or trypsin and subsequently incubated in buffer, indicating that these preparations are not suitable for intact cell studies.

show abstract

Section: Resultsmentioning

confidence: 63%

mentioning

confidence: 99%

Sialic acid uptake by fibroblasts

Hirschberg¹,

Goodman²,

Green³

1976

Biochemistry

View full text Add to dashboard Cite

show abstract

“…However, for such a mechanism to take place one would have to postulate a very low concentration of the intermediate radiolabeled N-acetylmannosamine. An unequivocal answer to this problem can be obtained by using a mixture of [1-I4C] -and [4,5,6,7,8,9-3H] -N-acetyl neuraminic acid as precursor; such Although analyses of the PTA-soluble material have shown radiolabeled sialic acid…”

Section: Discussionmentioning

confidence: 99%

“…An aliquot was applied to a thin layer plate and developed in chloroform-methanol-water, 60:35:8, as previously described (6). Standard hematoside was obtained by growing cells with l-['4C]-palmitate (7).…”

Section: Lipid Extractionmentioning

confidence: 99%

Sialic acid uptake by BHK cells and subsequent incorporation into glycoproteins and glycolipids

Hirschberg¹,

Yeh²

1977

J Supramol Struct

Self Cite

View full text Add to dashboard Cite

show abstract

Transformed cells have lost control of ribosome number through their growth cycle

Stanners

Adams

Harkins

et al. 1979

Journal Cellular Physiology

View full text Add to dashboard Cite

Previous studies on the synthesis and function of the protein synthetic machinery through the growth cycle of normal cultured hamster embryo fibroblasts (HA) were extended here to a series of four different clonal lines of polyoma virus-transformed HA cells. Under our culture conditions, these transformed cells could enter a stationary phase characterized by no mitotic cells, very low rates of DNA synthesis, and arrest in a post-mitotic pre-DNA synthetic state. Cellular viability was initially high in stationary phase but, unlike normal cells, transformed cells slowly lost viability. The rate of protein synthesis in the stationary phase of the transformed cells fell to 25-30% of the exponential rate. Though this reduction was similar to that seen in normal cells, it was accomplished by different means. The specific reduction in the ribosome complement per cell to values below that of any cycling cell seen in normal cells, was not seen in any of the transformed lines. This observation, which implies a loss of normal control of ribisome synthesis through the growth cycle after transformation, was confirmed in normal Chinese hamster embryo fibroblasts and transformed CHO cell lines. Normal control of ribosome synthesis was restored in L-73 and LR-73, growth control revertants of one of the transformed CHO lines. The transformed lines reduced their protein synthetic rates in stationary phase either by a greater reduction in the proportion of functioning ribosomes than that seen in normal cells or by a decrease in the elongation rate of functioning ribosomes; the latter effect was not seen in the normal cells. A model for growth control of normal cells and its derangement in transformed cells is presented.

show abstract

Synthesis of glycolipids and phospholipids in hamster cells: Dependence on cell density and the cell cycle

Cited by 13 publications

References 14 publications

Sialic acid uptake by fibroblasts

Sialic acid uptake by fibroblasts

Sialic acid uptake by BHK cells and subsequent incorporation into glycoproteins and glycolipids

Transformed cells have lost control of ribosome number through their growth cycle

Contact Info

Product

Resources

About