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N Zagris

Publications and source records attributed to N Zagris.

23 records · Page 2Linked to original sources
PubMed1980

Erythroid cell differentiation in unincubated chick blastoderm in culture.

Morphologically distinct erythroid cell types characteristic of the primitive and the definitive erythroid cell lines, and embryonic and adult haemoglobins are produced when the unincubated chick blastoderm is cultured ventral side down on a filter raft to inhibit morphogenetic movements and subsequent primitive-streak formation mechanically in serum-free minimal essential medium. The primitive and definitive erythroid cell populations appear consecutively in culture even though there is no axis formation nor apparent morphogenesis. The information to produce both the early and late haemoglobins and erythroid cell types is independent of axis formation and of specific extra-embryonic influences, such as progressive induction exerted by the yolk mass.

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PubMed1979

Differentiation capacity of unincubated chick blastoderm in culture.

Unincubated (stage X) chick blastoderms cultured in plain Dulbecco's modified Eagle medium in the absence of serum, synthesize haemoglobin and melanin 2 . 5--3 . 0 and 6 . 0--7 . 0 days, respectively, after the beginning of culture. The capacity of unincubated blastoderm to form haemoglobin and melanin is a response to intrinsic genotypic instructions rather than to the active intervention of substances continuously supplied by the yolk. 5-Bromodeoxyridine, applied during the first and second days of unincubated blastoderm in culture, is incorporated into DNA and perturbs the formation of haemoglobin and melanin, perhaps, by modifying gene expression.

Animals↗
PubMed1977

Translation of endogenous message in embryonic chick erythroid cell polysomes in a cell-free protein-synthesizing system.

Polysomes from 5.5-day and 6.5-day embryonic chick erythroid cells contain messenger RNA (mRNA) which can be translated into products in a cell-free protein-synthesizing system. The products of the cell-free system coelectrophoresed with carrier globin chains from the cells from which the polysomal pellet was isolated. Wheat germ S30 fraction increases by 1.5--2.0 fold [3H] leucine incorporation into trichloroacetic acid-precipitable material directed by the endogenous mRNA on chick erythroid cell polysomes. The wheat germ probably provides a specific factor or factors absent in a shortage in the incubation medium.

Animals↗
PubMedDate not supplied

Hemoglobins in single chick erythrocytes as determined by a differential elution procedure.

The switch from embryonic to adult hemoglobin (Hb) has been studied in vivo by a correlated cytological and electrophoretic analysis of circulating red blood cells from early, purely embryonic-Hb stages to purely adult-Hb stages including the adult chicken. It has been discovered, by using an acid buffer treatment that selectively elutes adult but not embryonic Hb from intact red blood cells, that embryonic and adult Hbs occur together in single cells, and that the switch occurs simultaneously in all cells. These results together with knowledge of the chick erythroid cell dynamics and ontogenetic titers indicate that the initiation of adult Hb synthesis occurs in the circulation in cells previously committed only to embryonic Hb synthesis.

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