Canal de Castilla Rey (Palencia), considered the beginning of the Northern Branch, Valladolid and Medina de Rioseco, lying at the end of the Southern Branch and Campos Branch respectively. The countryside crossed by the canal is of interest for its birdlife. In the Tierra de Campos there are two large Special Protection Areas ("La Nava-Campos Norte" and "La Nava-Campos Sur") which are notable for the birds such as great bustards ("Otis tarda") which live in the dryland farming areas (sometimes described as "steppes") which are typical of the region. The canal, on the other hand, provides habitats for wetland birds such as the
Porphyria cutanea tarda Porphyria cutanea tarda Porphyria cutanea tarda (PCT) is the most common subtype of porphyria. The disease is named because it is a porphyria that often presents with skin manifestations later in life. The disorder results from low levels of the enzyme responsible for the fifth step in heme production. Heme is a vital molecule for all of the body's organs. It is a component of hemoglobin, the molecule that carries oxygen in the blood. Hepatoerythropoietic porphyria has been described as a homozygous form of porphyria cutanea tarda, although it can also be caused if two different mutations occur at the