The occurrence and nature of Euglena gracilis proteins that bind vitamin B12

Daisley, K. W.

doi:10.1016/0020-711x(70)90024-8

Cited by 13 publications

(11 citation statements)

References 26 publications

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“…Denaturation of the binders by heat and by a protease implies that the binders are most probably proteins. This is consistent with the observations of Daisley (1970) and Pintner and Altmeyer (1979).…”

Section: Stability Of the B Bindersupporting

confidence: 82%

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Vitamin B,2 binding by microalgal exocrines: dissociation constant of the vitamin-binder complex determined using an ultrafiltration technique

Davies¹,

Leftley²

1985

Mar. Ecol. Prog. Ser.

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A simple, rapid ultrafiltration technique has been used to separate free vitamin B12 from that attached to the binding factor present in the media of cultures of the marine microalgae Mantoniella squamata and Pavlova lutheri (auxotrophic spec~es), and Dunaliella primolecta and Phaeodactylum tricomuturn (species with no B12 requirement). The dissociation constant (K,) for the B12-binder complex calculated from the results lies in the range 10-l2 to 10-l0 M indicating that the binder has a very high affinity for the vitamin. The ecological implications of the data are discussed in the light of our present understanding of B12 uptake by microalgae.

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Section: Stability Of the B Bindersupporting

confidence: 82%

“…To date, the only algal B,,-binder that has in any way been characterised is a glycoprotein of MW ca. 200,000 produced by Euglena gracilis (Daisley, 1970).…”

Section: Introductionmentioning

confidence: 99%

Vitamin B,2 binding by microalgal exocrines: dissociation constant of the vitamin-binder complex determined using an ultrafiltration technique

Davies¹,

Leftley²

1985

Mar. Ecol. Prog. Ser.

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“…In addition, we found that cells kept in the original medium after B12 replenishment respond less to B12 replenishment than those transferred to fresh medium containing no B12 or to a resting medium (unpublished data). This suggests that the original medium contains inhibitory substances, some of which may possibly be the B12 binding protein factors secreted by the cells as indicated by Daisley (5). Our data also indicate that cycloheximide does not seem to interfere with the uptake of B12 in contrast to the finding of Evans (9) that cycloheximide interferes with the uptake of glucose and 2,4-dinitrophenol in Euglena.…”

Section: Discussionsupporting

confidence: 65%

VITAMIN B12 AND THE MACROMOLECULAR COMPOSITION OF EUGLENA

Goetz

Johnston

Carell

1974

The Journal of Cell Biology

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When cycloheximide is added to (B12)-deficient cultures before or after replenishment of the cells with B12, reversion of these cells is inhibited. This inhibition is not caused by interference of the inhibitor in the uptake of B~2 as measured by division kinetics. Cycloheximide does not inhibit the initial increase in the rate of DNA synthesis caused by B~z replenishment, but within 30-45 rain the rate decreases and DNA synthesis ceases. Cycloheximide added to replenished deficient cells after completion of DNA duplication inhibits cell division. The total cellular protein and R N A in replenished cells treated with cycloheximide does not change. B~2 added to deficient cells does not stimulate the incorporation of [14C]leucine into protein during resumption and completion of DNA duplication. However, there is a large increase in [14C]leucine incorporation into the protein of these cells soon after completion of DNA duplication and before resumption of cell division. The addition of cycloheximide to Bt2-replenished or to nonreplenished deficient cells rapidly inhibits the incorporation. We suggest that the addition of B~ accelerates the rate of DNA synthesis in the deficient cells and that possibly no new protein synthesis is required except for mitosis. However, protein synthesis is needed for continuous DNA synthesis.

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“…Not only have algae been shown to have binding sites on the cell wall but 984 J. M. S C O T T the cells release binding factor into the surrounding medium (Droop, 1968;Daisley, 1970). Not only have algae been shown to have binding sites on the cell wall but 984 J. M. S C O T T the cells release binding factor into the surrounding medium (Droop, 1968;Daisley, 1970).…”

Section: Introductionmentioning

confidence: 99%

The Vitamin B₁₂Requirement Of The Marine RotiferBrachionus Plicatilis

Scott

1981

J. Mar. Biol. Ass.

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The marine rotifer Brachionus plicatilis has been found to have a definite vitamin B 12 requirement. The vitamin is taken up directly from solution and not from the food-algae. The rate of uptake by the rotifer has been found to be o-i pg/animal/day. It is suggested that vitamin B 12 may not be atypical of water soluble micronutrients and that many of these nutrients may be taken-up in this way by the rotifer. B 12 excreted by the alga Dunaliella has been shown to be a source of the vitamin for the animal, but intracellular cobalamins are not available.The vitamin B 12 uptake rates by the food-algae Brachiomonas and Dunaliella were determined and the saturation level measured for the latter. This alga, which is a non-B 12 requirer was found not to synthesize sufficient vitamin to support rotifer growth in the absence of external free vitamin Bi 2 .

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The occurrence and nature of Euglena gracilis proteins that bind vitamin B12

Cited by 13 publications

References 26 publications

Vitamin B,2 binding by microalgal exocrines: dissociation constant of the vitamin-binder complex determined using an ultrafiltration technique

Vitamin B,2 binding by microalgal exocrines: dissociation constant of the vitamin-binder complex determined using an ultrafiltration technique

VITAMIN B12 AND THE MACROMOLECULAR COMPOSITION OF EUGLENA

The Vitamin B₁₂Requirement Of The Marine RotiferBrachionus Plicatilis

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The occurrence and nature of Euglena gracilis proteins that bind vitamin B12

Cited by 13 publications

References 26 publications

Vitamin B,2 binding by microalgal exocrines: dissociation constant of the vitamin-binder complex determined using an ultrafiltration technique

Vitamin B,2 binding by microalgal exocrines: dissociation constant of the vitamin-binder complex determined using an ultrafiltration technique

VITAMIN B12 AND THE MACROMOLECULAR COMPOSITION OF EUGLENA

The Vitamin B12Requirement Of The Marine RotiferBrachionus Plicatilis

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The Vitamin B₁₂Requirement Of The Marine RotiferBrachionus Plicatilis