Images Dated 24th November 2006

Glasswing butterflies

Glasswing butterflies (Greta oto). This semi- transparent butterfly is native to Central America. It is not easy to see because of its partially transparent wings, which can also make it difficult for predators to recognise it as a butterfly

© POWER AND SYRED/SCIENCE PHOTO LIBRARY

American, Animal, Biological, Biology, Butterflies, Butterfly, Duo, Entomology, Fauna, Foliage, Glasswing Butterfly, Greta Oto, Insect, Insecta, Invertebrate, Invertebrates, Leaf, Leaves, Nature, Pair, Plant, Semi Transparent, Transparent, Wildlife, Zoological, Zoology

Ecological food web

Ecological food web, computer artwork. This model represents the extinct ecosystem of the Messel pit, Germany. Fossil animal and plant life is represented by the coloured nodes. Red nodes are lowest trophic level organisms such as plants and detritus, orange represents intermediate species and yellow represents top level species and primary predators. Relationships between organisms are shown by the connecting lines. Thick lines connect to predator species and thin lines connect to prey. Food webs are used by biologists to study species interaction. The Messel pit was formed 50 million years ago and contains a large number of fossils. Model created by Neo Martinez, Pacific Ecoinformatics and Computational Ecology Lab, USA

© NEO MARTINEZ/SCIENCE PHOTO LIBRARY

Januvia diabetes drug molecule

Januvia diabetes drug, molecular model. Januvia (sitagliptin) is a hypoglycaemic drug, one that reduces blood sugar levels. Diabetes is a condition in which blood sugar levels can get dangerously high due to a lack of insulin, the hormone that reduces them. Januvia works by inhibiting the enzyme dipeptidyl peptidase-4 (DPP- 4). DPP-4 rapidly deactivates the incretin hormone GLP-1 (glucagon-like peptide 1), which promotes insulin release. Hence, inhibiting DPP-4 prolongs the effects of GLP-1, keeping insulin levels high. Atoms are colour-coded: carbon (grey), hydrogen (yellow), oxygen (red), nitrogen (blue) and fluorine (green). Januvia is marketed by Merck, and was approved in the USA in October 2006

© DR MARK J. WINTER/SCIENCE PHOTO LIBRARY