Cretaceous & Jurassic Colors Come to Light

Recently, the era of the dinosaurs regained some of its actual coloring. Two studies published online in the journals Nature (Zhang and others, 2010) and Science (Li and others, 2010) describe plumage coloring in two small dinosaur species, Sinosauropteryx prima and Anchiornis huxleyi, from the early Cretaceous (ca. 125 million years ago) and the late Jurassic period (ca. 150 million years ago), respectively.

As in modern birds, pigments determine plumage color in dinosaurs. Researchers from the People's Republic of China, Great Britain and the United States achieved to accurately reconstruct patterns of pigment-bearing structures known as melanosomes in the feathers of dinosaur fossils from China. The reconstructions render two seemingly flightless bird-like creatures with clawed wings and richly-colored plumage.

 Sinosauropteryx prima

Zhang and others (2010)

Anchiornis huxleyi

Sloan (2010)

References

• Li Q, Gao K-Q, Vinther J, Shawkey MD, Clarke JA, D'Alba L, Meng Q, Briggs DEG, Miao L, Prum RO (2010) Plumage color patterns of an extinct dinosaur. Science doi: 10.1126/science.1186290.
• Sloan C (2010) True-color dinosaur revealed -- first full-body rendering. National Geographic Daily News.
• Zhang F, Kearns SL, Orr PJ, Benton MJ, Zhou Z, Johnson D, Xu X, Wang X (2010) Fossilized melanosomes and the colour of Cretaceous dinosaurs and birds. Nature doi:10.1038/nature08740.

Annotations to Groundhog Day

Yesterday, the United States celebrated Groundhog Day. Punxutawney Phil saw his shadow. Winter will continue six more weeks.

Groundhog Day is an adaption of a tradition that German immigrants brought to Pennsylvania. The species used in Germany is a nocturnal relative of the squirrels called Siebenschläfer (Glis glis). Literally translated, Siebenschläfer means "sleeping seven". The animals hibernate for roughly seven months. They like to nest in the attic of our homes where they shuffle around all night, disrupting our well-deserved sleep. They bear no resemblance with groundhogs.

Germans celebrate Siebenschläfer Day on June 27. Legend has it that on that day seven young Christians emerged from a cave in Asia minor after sleeping for 195 year. They had been walled in alive during the persecution of Christians by the Roman Emperor Decius. Weather on Siebenschläfer Day is supposed to forecast weather for seven weeks to come. Depending on local customs, predictions vary from more of the same to the contrary.

Cell Conversion: Potential Solution for Neurodegenerative Diseases

About 10 percent of the genes in the human genome encode transcription factors. Transcription factors are proteins that bind to DNA, controlling gene expression. Notably, they control the precisely-timed differentiation of stem cells into specialized tissues during the development of organisms.

In an article published online in the journal Nature this week, Marius Wernig and colleagues at Stanford University demonstrate that the expression of only three transcription factors, that is Ascl1, Pou3f2 and Myt1l, is needed to convert cultured fibroblasts, that is undifferentiated connective tissue cells, into nerve cells (Vierbuchen and others, 2010). The cells were shown to produce action potentials, i.e. the electrical discharges that propagate along their output processes called axons, and formed functional connections, known as synapses, with other nerve cells.

Although the conversion has been successfully carried out only in a dish with developing mouse tissue and only the most essential nerve cell functions have been demonstrated, the method does not utilize stem cells and still may bear great potential for therapies, seeking to replace lost nerve cells in neurodegenerative diseases, e.g. Parkinson's disease.

References

• Vierbuchen T, Ostermeier A, Pang ZP, Kokubu1 Y, Südhof TC, Wernig M (2010) Direct conversion of fibroblasts to functional neurons by defined factors. Nature: online.

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