Science Progress (2005), 88(2)

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Intracellular and extracellular components as bacterial

thermometers, and early warning against thermal stress

ROBIN J. ROWBURY

ABSTRACT

Responses induced by cold or heat are triggered following detection of

temperature changes by specific sensing molecules, complexes or structures.

Low temperature responses are often induced following sensing of coldinduced

falls in membrane fluidity, such changes turning-on or -off enzymic

activities in membrane proteins, although ribosomes and DNA may also

function in cold perception. Many thermal sensors are components of

structures damaged by the heat, with sensing involving changes to ribosomes,

DNA, intracellular proteins and, less commonly, membrane fluidity. Additionally,

secreted proteins (extracellular sensing components, ESCs) detect

temperature increases i.e. act as thermometers, with ESC activation in the

medium, by the stimulus, converting such sensors to extracellular signalling

molecules, the extracellular induction components (EICs), which induce

thermal responses. Several ESCyEIC pairs trigger thermal responses, and

have the unique property of giving early warning of the stress by diffusing to

regions (and organisms) not yet exposed to elevated temperatures.

Keywords: unique form of thermal sensor, external medium, bacterial sensor

Making sense of lanthanide

luminescence

MARTINUS H.V. WERTS

ABSTRACT

The luminescence of trivalent lanthanide ions has found applications in

lighting, lasers, optical telecommunications, medical diagnostics, and various

other fields. This introductory review presents the basics of organic and

inorganic luminescent materials containing lanthanide ions, their applications,

and some recent developments. After a brief history of the discovery,

purification and early spectroscopic studies of the lanthanides, the radiative

and nonradiative transitions of the 4f electrons in lanthanide ions are

discussed. Lanthanide-doped phosphors, glasses and crystals as well as

luminescent lanthanide complexes with organic ligands receive attention

with respect to their preparation and their applications. Finally, two recent

developments in the field of luminescent materials are addressed: nearinfrared

luminescent lanthanide complexes and lanthanide-doped nanoparticles.

Keywords: lanthanide, luminescence, nanoparticles, photonics