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Effects of 5-fluorodeoxyuridine and related halogenated pyrimidines on the sand-dollar embryo
Abstract:
The embryo of the sand-dollar (Echinarachnius parma) was exposed to various concentrations of fluorinated pyrimidines immediately after fertilization. FUDR (5-fluorodeoxyuridine) was most active, and a concentration of 2 to 4 mgamma/10 cc. (0.8 to 1.6 x 10(-6) m.eq./liter) blocked development at the early blastula stage. Larger doses interrupted development at the same stage. This effect was prevented by thymidine (TDR) and thymine (T); and these pyrimidines protected against many times the minimal lethal concentration of FUDR. TDR was active as a protective agent if added just before early blastula formation. The other fluorinated pyrimidines, 5-fluorouracil (FU), 5-fluorouridine (FUR), 5-fluorocytidine (FCR), 5-fluorodeoxycytidine (FCDR), and 5-fluoroorotic acid (FO), were also studied. These drugs produced effects on embryonic development similar to those seen with FUDR. The effective concentrations, however, varied greatly. T and TDR provided protection against these drugs, but in most cases they were not so effective as against FUDR. 5-Bromodeoxyurdine (BrUDR), beginning at the early blastula stage, caused a random pattern of embryonic death up to the pluteus stage. This drug has been shown to be incorporated into bacterial DNA. BrUDR protected embryos against the early lethal effects of FUDR presumably acting as a thymidine substitute, but the embryos died subsequently in a pattern similar to that seen with BrUDR alone. FUDR and BrUDR appear to inhibit the formation and alter the structure of DNA, respectively, distinctive effects whch may provide a means for studying the role of DNA in embryonic development.
Insights
Fluorinated pyrimidines like FUDR disrupt sand-dollar embryo development by interfering with DNA. Thymidine and thymine can prevent these effects, offering insights into DNA
Area of Science:
- Developmental Biology
- Molecular Biology
- Marine Biology
Background:
- Fluorinated pyrimidines are known to interfere with nucleic acid synthesis.
- Understanding the impact of these compounds on early embryonic development is crucial.
Purpose of the Study:
- To investigate the effects of various fluorinated pyrimidines on sand-dollar (Echinarachnius parma) embryo development.
- To determine the protective role of thymidine and thymine against these effects.
- To explore the potential of these compounds in studying DNA's role in development.
Main Methods:
- Exposing sand-dollar embryos to different concentrations of fluorinated pyrimidines (FUDR, FU, FUR, FCR, FCDR, FO, BrUDR) post-fertilization.
- Administering thymidine (TDR) and thymine (T) to assess their protective capabilities.
- Observing and documenting developmental stages and mortality patterns.
Main Results:
- 5-fluorodeoxyuridine (FUDR) at low concentrations blocked early blastula development, an effect preventable by thymidine and thymine.
- Other fluorinated pyrimidines showed similar developmental disruption, with varying effective concentrations.
- 5-Bromodeoxyuridine (BrUDR) incorporation into DNA led to subsequent embryonic death.
Conclusions:
- Fluorinated pyrimidines significantly impact sand-dollar embryonic development, primarily affecting DNA formation and structure.
- Thymidine and thymine act as effective protectants against FUDR-induced developmental arrest.
- These findings highlight the utility of FUDR and BrUDR in researching DNA's role in embryonic processes.
