Fast forward in the MHC

Article Abstract:

Genetic analyses of the class I major histocompatibility complex (MHC) molecule among North and South American Indian tribes indicated that they lacked the high degree of allelic diversity characteristic of Old World peoples. This research, which takes advantage of MHC's capacity to indicate genetic diversity, confirms the view that the Indians' genes derived from a limited number of alleles that came over from Asia with mongoloid immigrants. The Indians' variations in HLA-B, an MHC loci, are true novelties not found among any other group of people.

Genetic aspects, Native Americans, Native North Americans, Human genetics, South American native peoples, Native South Americans

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A small metalloribozyme with a two-step mechanism

Article Abstract:

The divalent metal ions Pb2+ and Mg2+ can cleave a catalytic RNA molecule made up of an asymmetric internal loop of six to 10 nucleotides. This catalytic RNA is in the form of a small metalloribozyme with a two-step reaction mechanism; first a 2',3'-cyclic phosphodiester produces a 3' phosphomonoester which then terminates with a 5' cleavage product. This two-step process is similar to what occurs in many protein ribonucleases but has not hitherto been detected in catalytic RNA reactions.

Catalytic RNA, Metal ions

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First class way to develop a brain

Article Abstract:

Carla Shatz and colleagues have demonstrated that there are large amounts of surface-expressed major histocompatibility complex (MHC) glycoproteins in the optic system, and that they could be involved in synaptic remodelling during development. Expression of class one MHC in the lateral geniculate nucleus (LGN) was found to be highest during late fetal and early neonatal development stages. It is predicted that MHC levels in the cortex can be sustained by the inputs from only one eye.

Neurobiology

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