Review of Chemical Signals: Vertebrates and aquatic invertebrates.

1980 ◽  
Vol 25 (10) ◽  
pp. 848-848
Author(s):  
DONALD A. DEWSBURY
Keyword(s):  
Aquatic Invertebrates ◽  
Chemical Signals

A Mechanism for Reversibly Pausing a Self-Immolation Cascade in Response to pH Changes

2019 ◽  
Author(s):  
Derrick Roberts ◽  
Ben S. Pilgrim ◽  
Tristan Dell ◽  
Molly Stevens
Keyword(s):  
Local Environment ◽  
Chemical Signals ◽  
Ph Sensitive ◽  
First Report ◽  
Ph Changes ◽  
Self Immolation

We describe the first report of a self-immolation cascade that can be reversibly paused and reactivated in response to pH changes. This system employs a triazole-based self-immolative linker, which expresses a pH-sensitive intermediate during its elimination sequence. This allows the system to respond to pH cues within its local environment, thus establishing a new way to gate self-immolative release using fluctuating or transient chemical signals.<br>

A Novel Method for the Analysis of Volatile Organic Compounds (VOCs) from Red Flour Beetle Tribolium castaneum (H.) using Headspace-SPME Technology

2020 ◽  
Vol 16 (4) ◽  
pp. 404-412 ◽  
Author(s):  
Ihab Alnajim ◽  
Manjree Agarwal ◽  
Tao Liu ◽  
YongLin Ren
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Tribolium Castaneum ◽  
Solid Phase ◽  
Chemical Signals ◽  
Red Flour Beetle ◽  
Specific Chemical ◽  
Flour Beetle ◽  
Volatile Organic ◽  
Spme Fibre

Background: The red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) is one of the world’s most serious stored grain insect pests. A method of early and rapid identification of red flour beetle in stored products is urgently required to improve control options. Specific chemical signals identified as Volatile Organic Compounds (VOCs) that are released by the beetle can serve as biomarkers. Methods: The Headspace Solid Phase Microextraction (HS-SPME) technique and the analytical conditions with GC and GCMS were optimised and validated for the determination of VOCs released from T. castaneum. Results: The 50/30 μm DVB/CAR/PDMS SPME fibre was selected for extraction of VOCs from T. castaneum. The efficiency of extraction of VOCs was significantly affected by the extraction time, temperature, insect density and type of SPME fibre. Twenty-three VOCs were extracted from insects in 4 mL flask at 35 ± 1°C for four hours of extraction and separated and identified with gas chromatography-mass spectroscopy. The major VOCs or chemical signals from T. castaneum were 1-pentadecene, p-Benzoquinone, 2-methyl- and p-Benzoquinone, 2-ethyl. Conclusion: This study showed that HS-SPME GC technology is a robust and cost-effective method for extraction and identification of the unique VOCs produced by T. castaneum. Therefore, this technology could lead to a new approach in the timely detection of T. castaneum and its subsequent treatment.

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