Images Dated 8th January 2019

Streptococcus mutans, SEM

Streptococcus mutans. Coloured scanning electron micrograph (SEM). S. mutans is a coccoid shaped, Gram-positive, anaerobic bacteria that is part of the normal bacteria flora of the mouth. It metabolizes sucrose to lactic acid and is a leading cause of tooth enamel decay. The acidic environment created in the mouth by this process is what causes the highly mineralized tooth enamel to decay. S. mutans is one of a few specialized organisms equipped with receptors for adhesion to the surface of teeth. Sucrose is utilized by S. mutans to produce a sticky, extracellular, dextran-based polysaccharide (glucan) that allows them to adhere to each other forming plaque. Other sugars (glucose, fructose, lactose) can be digested by S. mutans to produce lactic acid. It is the combination of plaque and acid that leads to dental decay. Magnification: x8000 when printed at 10cm wide

© Science Photo Library

Sea ??cucumber, chromolithograph, published in 1897

Sea ??cucumber: 1) Oloturia (Cucumaria planci); 2) Serpent's table brittle star (Ophiura albida); 3) Seaweed. Chromolithograph, published in 1897

1091320366

EyeUbiquitous_20121069

Northern Ireland, County Derry, The Guild Hall, view from the city's 17th century walls with a row of cannons in the foreground

© Hugh Rooney / Eye Ubiquitous

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