new-science
Detection of pheromones and plant volatiles
September 6th 2009 03:46
One reads that olfaction is the oldest sense, although this is generally stated from
a human/vertebrate perspective and with the implication that olfaction was invented
in fish. Chemoreception is certainly one of the oldest senses, present in bacteria
and presumably one of those life essentials that was required of the earliest of
chemotrophic single celled organisms. Life would be quite irrelevant in the
absence of sensory input: no food, no escaping those who want to eat you, and
no sex. There would be no learning since there would be no input through which
one could learn anything, and no memory since there would be no means of
experiencing. Chemoreception presumably became established in prokaryotes
near the onset of life on earth, and became increasingly diversified and specialized
through the evolution of eukaryotes. Plant, fungus and animal lineages diverged
when organisms were still single celled; multicellularity developed independently
within each of these lineages. Animals developed unique means to communicate
between cells (cell-cell interactions and endocrine systems) and to coordinate
their body movements and behaviors (nervous systems and endocrine systems).
The detection of chemicals external to the animal body presumably became
transformed into what we now think of as taste and smell. Chemoreception is not
necessarily neuronal, but what we consider as smell and taste are clearly neuronal
processes. The mechanisms underlying smell and taste are those common to the
nervous system: neurons respond to external chemical stimuli (neurotransmitters
and neuropeptides) via receptor proteins in their membranes which activate ion
channels either directly (many receptors are themselves ion channels) or via
second messenger transductory systems (e.g. G-protein coupled receptors). These
processes are common to all those organisms that we consider animals, except
for sponges, which are somewhat transitional between single and multicellularity
and lack nervous systems. But even jellyfish have nervous systems that perform
the same cellular functions as our own.
Source Insect Pheromone 2009
a human/vertebrate perspective and with the implication that olfaction was invented
in fish. Chemoreception is certainly one of the oldest senses, present in bacteria
and presumably one of those life essentials that was required of the earliest of
chemotrophic single celled organisms. Life would be quite irrelevant in the
absence of sensory input: no food, no escaping those who want to eat you, and
no sex. There would be no learning since there would be no input through which
one could learn anything, and no memory since there would be no means of
near the onset of life on earth, and became increasingly diversified and specialized
through the evolution of eukaryotes. Plant, fungus and animal lineages diverged
when organisms were still single celled; multicellularity developed independently
within each of these lineages. Animals developed unique means to communicate
between cells (cell-cell interactions and endocrine systems) and to coordinate
their body movements and behaviors (nervous systems and endocrine systems).
The detection of chemicals external to the animal body presumably became
transformed into what we now think of as taste and smell. Chemoreception is not
necessarily neuronal, but what we consider as smell and taste are clearly neuronal
processes. The mechanisms underlying smell and taste are those common to the
nervous system: neurons respond to external chemical stimuli (neurotransmitters
and neuropeptides) via receptor proteins in their membranes which activate ion
channels either directly (many receptors are themselves ion channels) or via
processes are common to all those organisms that we consider animals, except
for sponges, which are somewhat transitional between single and multicellularity
and lack nervous systems. But even jellyfish have nervous systems that perform
the same cellular functions as our own.
Source Insect Pheromone 2009
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