Ubiquitous healthy diatoms in the deep sea confirm deep carbon injection by the biological pump.

The role of the ocean as a sink for CO2 is partially dependent on the downward transport of phytoplankton cells packaged within fast-sinking particles. However, whether such fast-sinking mechanisms deliver fresh organic carbon down to the deep bathypelagic sea and whether this mechanism is prevalent across the ocean requires confirmation. Here we report the ubiquitous presence of healthy photosynthetic cells, dominated by diatoms, down to 4,000 m in the deep dark ocean. Decay experiments with surface phytoplankton suggested that the large proportion (18%) of healthy photosynthetic cells observed, on average, in the dark ocean, requires transport times from a few days to a few weeks, corresponding to sinking rates (124-732 m d(-1)) comparable to those of fast-sinking aggregates and faecal pellets. These results confirm the expectation that fast-sinking mechanisms inject fresh organic carbon into the deep sea and that this is a prevalent process operating across the global oligotrophic ocean.

[Squamous cell carcinoma on a leg ulcer in the West Indies]. / Carcinome épidermoïde sur ulcère de jambe aux Antilles.

INTRODUCTION: The epidemiology of carcinoma developing on a leg ulcer is poorly, although high incidence rates are reported in Africa. PATIENTS AND METHODS: Retrospective study of cases reported in Guadeloupe, a tropical country with a large population from African descent and with high quality health care level. RESULTS: Sixteen cases, mean age 71, were diagnosed over a 10-Year period in the only referral hospital. The annual incidence was an estimated 0.4/100,000. Preceding ulcers had a long course (mean of 27 Years) and had various causes. Social distress was the rule (14/16 patients). One third of the clearly differentiated (15/16) squamous cell-type tumors exhibited metastatic extension on presentation. At Year 3, the mortality rate was of 40 p. cent. The best survival rate (6 remissions/8 cases) was associated with primary limb amputation. DISCUSSION: Malignant ulcers appeared more frequent in Guadeloupe than in the influent countries of the North, but with an instance 4-fold lower than in Africa. Like many other tropical diseases, socio-behavioral factors may play a major role.