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Photoreceptor pigment that induces differentiation in the slime mold Physarum polycephalum
Abstract:
An extract of small molecules (molecular weight less than 500) of the slime mold Physarum polycephalum undergoes a shift in ultraviolet-visible absorption spectrum upon illumination. This illumination also confers on the extract the ability to induce sporulation when injected into a starved, unilluminated slime mold. The spectral shift and appearance of the sporulation-inducing activity both occur regardless of whether the illumination is carried out on an intact slime mold or on the plasmodium-free extract itself. Thin-layer chromatography resolves the slime mold extract into four major visible fractions. One of these has high sporulation-inducing activity after illumination in vitro.
Insights
Light exposure triggers a spectral shift in Physarum polycephalum slime mold extracts. This illuminated extract gains the ability to induce sporulation in other slime molds, with one fraction showing high activity.
Area of Science:
- Biochemistry
- Cell Biology
- Mycology
Background:
- The slime mold Physarum polycephalum is a model organism for studying cellular processes.
- Sporulation is a critical developmental stage in the life cycle of many fungi and protists.
Purpose of the Study:
- To investigate the effect of illumination on the ultraviolet-visible absorption spectrum of Physarum polycephalum small molecule extracts.
- To determine if light-induced changes in the extract confer sporulation-inducing activity.
- To identify specific components within the extract responsible for this activity.
Main Methods:
- Extraction of small molecules (<500 Da) from Physarum polycephalum.
- Illumination of intact slime mold and cell-free extracts.
- Spectrophotometric analysis of ultraviolet-visible absorption.
- Injection of extracts into starved, unilluminated slime molds to assess sporulation induction.
- Thin-layer chromatography to fractionate the extract.
Main Results:
- Illumination caused a distinct shift in the ultraviolet-visible absorption spectrum of the slime mold extract.
- The illuminated extract, whether from intact or cell-free samples, induced sporulation upon injection.
- Thin-layer chromatography separated the extract into four major visible fractions.
- One specific fraction exhibited potent sporulation-inducing activity after in vitro illumination.
Conclusions:
- Light-induced spectral changes in Physarum polycephalum extracts correlate with the acquisition of sporulation-inducing capabilities.
- The sporulation-inducing activity is intrinsic to specific small molecules within the extract.
- This finding opens avenues for understanding light-mediated signaling and developmental triggers in slime molds.