Origin of the spider's head

Article Abstract:

Structure comparisons of heads of different classes of arthropod have often been controversial. Studies based on the expression of developmental genes by Damen and colleagues and Telford and Thomas, provide evidence of unexpected homologies. The homeotic (Hox) genes were studied and the identification and expression of such genes in two different Chelicerata, showed that expression of Hog genes in the prosoma of chilcerates is similar to homologous gene expression in the heads of other arthropods.

Author: Averof, Michalis
Physiological aspects, Observations, Morphology (Biology), Morphology, Arthropoda, Arthropods

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The nitrogen fix

Article Abstract:

Research describing the origins of metabolically usable nitrogen is presented. In particular the possibility of a sharp fall in the rate of abiotic nitrogen fixation by lightning in the early history of the earth is investigated.

Author: Kasting, James F., Siefert, Janet L.
Nitrogen-fixing microorganisms

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Subjects list: Research, Evolution (Biology), Evolution
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