Related Experiment Video
Updated: May 5, 2026
14:39
Measuring Phagosome pH by Ratiometric Fluorescence Microscopy
Published on: December 7, 2015
13.7K
A substance which acts as a pH indicator from the mothEuchloron megaera L
1Institut de Chimie des Substances Naturelles, CNRS, 91190, Gif sur Yvette, France.
Journal of Chemical Ecology
|December 10, 2013
Summary
The green pigment in Euchleron megaera moth wings acts as a pH indicator. This pigment is an anthocyanidin derivative, likely acquired from the moth's plant-based diet.
Area of Science:
- Biochemistry
- Entomology
- Chemical Ecology
Background:
- Moth wing scales can contain pigments with unique properties.
- The moth Euchleron megaera (Sphingidae) exhibits a distinctive green coloration.
- pH indicator properties in animal pigments are of scientific interest.
Purpose of the Study:
- To isolate and characterize the water-soluble green pigment from Euchleron megaera moth wings.
- To determine the chemical nature and origin of the pigment.
- To investigate the potential ecological role of the pigment.
Main Methods:
- Isolation of the green pigment from moth wing scales.
- Spectroscopic analysis (UV-visible).
- Thin-layer chromatography (TLC) on SiO2.
- Chemical reduction using dithionite.
- Assessment of pH indicator properties.
Main Results:
- The isolated green pigment exhibits pH indicator properties.
- Spectra and chemical properties suggest the pigment is an anthocyanidin derivative.
- The pigment's characteristics align with those found in plants of the Apocynaceae family.
- The pigment is water-soluble and has a high molecular weight.
Conclusions:
- The green pigment in Euchleron megaera is likely derived from its plant food, specifically anthocyanidins from Nerium sp.
- A proposed hypothesis suggests the pigment forms from a reaction between plant anthocyanidins and animal constituents (NH2 groups).
- Similar pigments in other Sphingidae moths may serve aposematic (warning) functions, suggesting a potential role for this pigment as well.
Related Concept Videos
02:39Indicators
45.1K
Certain organic substances change color in dilute solution when the hydronium ion concentration reaches a particular value. For example, phenolphthalein is a colorless substance in any aqueous solution with a hydronium ion concentration greater than 5.0 × 10−9 M (pH < 8.3). In more basic solutions where the hydronium ion concentration is less than 5.0 × 10−9 M (pH > 8.3), it is red or pink. Substances such as phenolphthalein, which can be used to determine the pH...
45.1K
01:18Titration of Polyprotic Base with a Strong Acid
4.7K
The titration of a polyprotic base such as sodium carbonate with a strong acid such as hydrochloric acid results in two equivalence points on the titration curve. At the first equivalence point, the carbonate ions in the base are completely converted to bicarbonate ions. The second equivalence point corresponds to the complete conversion of bicarbonate ions to carbonic acid, which dissociates into carbon dioxide and water. The region before the first equivalence point corresponds to the...
4.7K
01:31Transport Number
230
The transport number is the fraction of the total current carried by an ion in an electrolyte solution. It is defined as the ratio of the current carried by a specific ion to the total current flowing through the solution. The transport number, t, is central to understanding ionic mobility, which describes how fast an ion moves under the influence of an electric field. This link connects the physical behavior of ions in solution to the chemical processes that occur during electrochemical...
230
01:19Precipitation Titration: Endpoint Detection Methods
5.1K
In argentometric precipitation titrations, endpoints can be detected visually by the Mohr, Volhard, and Fajans methods. In the Mohr method, adding a soluble chromate indicator gives an initial yellow color to the analyte solution. As the titrant is added, the first excess of silver ions forms a red silver chromate precipitate, marking the endpoint. The solution pH should be maintained at about 8 by adding solid CaCO3.
In the Volhard method, a standard excess of AgNO3 is first added to the...
In the Volhard method, a standard excess of AgNO3 is first added to the...
5.1K
00:39Complexometric Titration: Overview
10.9K
Complexometric titration involves the formation of a complex by reacting a metal ion with one or more ligands. A visual indicator often detects the end point of a complexometric titration. It is added to the metal solution before the titration, forming a stable metal–indicator complex and imparting color to the solution. As the titration approaches the equivalence point, the excess of the added ligand displaces the indicator from the metal–indicator complex, releasing the free...
10.9K
01:14Photoluminescence: Applications
1.3K
Photoluminescence offers a wide range of applications due to its inherent sensitivity and selectivity. This technique allows for both direct and indirect analyses of the analyte. Direct quantitative analysis is possible when the analyte exhibits a favorable quantum yield for fluorescence or phosphorescence. However, an indirect analysis may be feasible if the analyte is not fluorescent or phosphorescent, or if the quantum yield is unfavorable. Indirect methods include reacting the analyte with...
1.3K