Embryology

“The hourglass model of embryonic evolution predicts an hourglass-like divergence during animal embryogenesis – with embryos being more divergent at the earliest and latest stages but conserved during a mid-embryonic (phylotypic) period that serves as a source of the basic body plan for animals within a phylum.” Well, not so fast: From Hajk-Georg Drost, Philipp Janitza, Ivo Grosse, and Marcel Quint at Current Opinion in Genetics & Development: • Developmental hourglass patterns are not specific for animals. • In plants, developmental hourglass patterns are associated with embryogenesis and post-embryonic phase transitions. • Morphological and transcriptomic patterns can be uncoupled. • The organizational checkpoint hypothesis proposes that developmental reprogramming inevitably results in evolutionarily conserved transition periods. The developmental hourglass model has Read More ›

Today is the March for life in Washington DC. Speakers include: Rep. Paul Ryan, Pam Tebow, Matt Birk and others. We have someone on the ground from the UD family and will be giving updates as we get them across the day. Remember, globally, the abortion holocaust toll rises at a million or thereabouts per week, on Guttmacher-UN figures. The total since the early 1970’s exceeds 800 millions. For shame! So, developing: U/D No 1: I found a live stream here. (I won’t even try an embed with this one.) U/D 2: US Pres Trump is to address the MFL by satellite feed, 100,000 expected. A first. U/D 3: Live address is to be at 1 pm EST, and will Read More ›

Here’s a news article from Phys.Org on a lamprey study. Actually it’s a study concerning phylogenetics and using gene regulatory mechanisms to figure out the relationships that exist. It turns out that in the lamprey, which is part of the Cambrian explosion, the same kind of hind brain gene regulatory mechanisms are in place as in “jawed” vertebrates, including mammals. From the article: The team at Stowers, collaborating with Marianne Bronner, Ph.D., professor of biology at Caltech, focused on the sea lamprey because the fossil record shows that its ancestors emerged from Cambrian silt approximately 500 million years ago, 100 million years before jawed fish ever swam onto the scene. The question was, could the hindbrain gene regulatory network that Read More ›