414
Plague a possible representation of mass deaths due to CO 2
degassing; also related to buboes found on CO 2 intoxi-
cated victims.
Primer Strand of nucleic acid that serves as a starting point
for DNA synthesis.
Prodigium unexplicable terrifying events in ancient Rome.
Interpreted as a disruption of the cosmic harmony or of
the anger of gods, they were reported to special authori-
ties who decided the necessary public rites to reset the
harmony. They have been listed by Julius Obsequens.
Many prodigii are related to the Colli Albani volcano near
Rome and its maar-lakes, including Lake Albano over-
spill in 398 BC.
Prophage a stable, inherited form of bacteriophage in
which the viral genetic material is integrated into the
bacterial host’s genome and is potentially replicated and
expressed.
Proteome all the proteins in a cell, a tissue, an organ or an
organism.
Proteomic science that studies the proteome (see proteome)
at a given time and under given conditions.
Protists (Protista syn. Protoctista) eukaryotic organisms
that are unicellular and sometimes colonial or less often
multicellular and that typically include the protozoans,
most unicellular algae, and often some fungi (as slime
molds).
Pseudolysogeny defined as the stage of stalled development
of a bacteriophage in a host cell without any multiplica-
tion of the phage genome (as in lytic development) nor
its synchronized replication with the cellular cycle (as in
lysogenic cycle) without viral genome degradation and
allowing the subsequent restart of virus development.
Pulse field gel electrophoresis technique used for the sepa-
ration of large DNA molecules into a gel matrix by apply-
ing an electric field that periodically changes direction in
order to minimize overlap of the spots due to diffusion
Pumice a pyroclast (tephra) that consists of highly vesicu-
lar, rough textured volcanic glass, which may or may not
contain crystals.
Pumices volcanic rock consisting of highly vesicular rough
textured volcanic glass, created when super- heated and
high-pressurized rock is violently ejected from a volcano.
Pyrite iron sulfide mineral (Fe(II)S(0)S(−II)) in the cubic
crystal system.
Pyrolysis thermochemical decomposition of organic mate-
rial at elevated temperatures in the absence of oxygen.
Pyrosequencing Pyrosequencing involves sequencing of
DNA by synthesizing the complementary strand of a sin-
gle base at a time, while determining the specific nucleo-
tide being incorporated during the synthesis reaction. The
reaction occurs on immobilized single stranded template
DNA where the four deoxyribonucleotides (dNTP) are
added sequentially and the unincorporated dNTPs are
enzymatically degraded before addition of the next dNTP
to the synthesis reaction.
Quantitative real-time PCR (qPCR) Technique based on
the polymerase chain reaction (PCR) which is used to
amplify and simultaneously detect or quantify a targeted
DNA molecule.
Quorum Sensing set of regulatory mechanisms that control
the coordinated expression of some bacterial genes within
a bacterial population.
REE REE, the 17 chemical elements in the periodic table
of the La(57) to Lu(71). LREE: light REE from La to
Eu (63); HREE: from Gd (64) to Lu (71). Sometimes
Sc(21) and Y(39) are also included as their behaviours are
respectively close to those of La and Lu.
Radiative Forcing difference of radiant energy received by
the Earth and energy radiated back to space.
Radiocarbon reservoir effect impact of carbon cycling
hydrodynamic conditions in the environment on radiocar-
bon age determinations. Radiocarbon ages of materials
are calculated by comparison to normal atmospheric CO 2
isotopic ratio. Dating materials not issued from terres-
trial plant remains but made of more carbon sources than
atmospheric CO 2 requires correcting radiocarbon ages by
specific age offsets depending of locally particular condi-
tions of the reservoir effect.
Rare biosphere collection of a huge number of low abun-
dant taxa that characterize microbial communities when
studied by molecular surveys.
Rarefaction curves Plot of the number of species as a func-
tion of the number of samples. In ecology, rarefaction is
a technique to assess species richness from the results of
sampling. Rarefaction allows the calculation of species
richness for a given number of individual samples, based
on the construction of so-called rarefaction curves.
Reaction quotient a function of the activities or concen-
trations of the chemical species involved in a chemical
reaction.
Recombination Molecular processes by which parts of two
different DNA molecules join and form a unique hybrid
molecule.
Reduction The gain of one or more electrons by an atom,
molecule, or ion.
Reflection acoustic horizon on seismic reflection or subbot-
tom profiles linked to a change in acoustic impedance that
is the product of sediment bulk density and sound wave
velocity.
Rhizoid (Rhizoidal system) Short, thin filament found in
fungi and in certain plants and sponge that anchors the
growing (vegetative) body of the organism to a substra-
tum and that is capable of absorbing nutrients. In fungi,
the rhizoid is found in the thallus and resembles a root.
It may serve either as a feeding organ (Rhizopus) or to
anchor the thallus to its substratum (Chytridium).Glossary