Genetic and selective factors in reduction of the hallux in Pongo pygmaeus

Extreme reduction of the hallux is unique to the orang-utan (Pongo pygmaeus) among Primates. Hallucal diminution has advanced so far that 60% of orang-utans lack both distal phalanges and nails. Absence of these structures occurs significantly more often in females than in males. Hypotheses on possible genetic control of the condition have been tested and indicate that either single gene inheritance or polygenic inheritance with variable expressivity is involved. Reduction of pollex and of hallux in Pongo have advanced with selection for a specialized four-digit grasp in hands and feet. Diminution has progressed farther in the great toe than in the thumb due to selection for fine manipulation in the latter digit.     

Laetoli toes andAustralopithecus afarensis

The probable misfit between feet, particularly toes II–V, of 3.0-million-year-oldAustralopithecus afarensis from Hadar, Ethiopia, and the 3.5-million-year-old hominid footprints at Site G, Laetoli, Tanzania, casts doubt thatA. Afarensis made the Laetoli trails. We suggest that another species ofAustralopithecus or an anonymous genus of the Hominidae, with remarkably humanoid feet, walked at Laetoli. It would be imprudent to declare thatHomo was present at Laetoli 3.5 million years ago (my) because there is no evidence of brain expansion, advanced tool manufacture, or other non-locomotor hallmarks of the human condition at Site G.     

The distribution and evolutionary history of the PRP8 intein

Background  

We recently described a mini-intein in the PRP8 gene of a strain of the basidiomycete Cryptococcus neoformans, an important fungal pathogen of humans. This was the second described intein in the nuclear genome of any eukaryote; the first nuclear encoded intein was found in the VMA gene of several saccharomycete yeasts. The evolution of eukaryote inteins is not well understood. In this report we describe additional PRP8 inteins (bringing the total of these to over 20). We compare and contrast the phylogenetic distribution and evolutionary history of the PRP8 intein and the saccharomycete VMA intein, in order to derive a broader understanding of eukaryote intein evolution. It has been suggested that eukaryote inteins undergo horizontal transfer and the present analysis explores this proposal.     

Age-Specific Mortality During the 1918 Influenza Pandemic: Unravelling the Mystery of High Young Adult Mortality

The worldwide spread of a novel influenza A (H1N1) virus in 2009 showed that influenza remains a significant health threat, even for individuals in the prime of life. This paper focuses on the unusually high young adult mortality observed during the Spanish flu pandemic of 1918. Using historical records from Canada and the U.S., we report a peak of mortality at the exact age of 28 during the pandemic and argue that this increased mortality resulted from an early life exposure to influenza during the previous Russian flu pandemic of 1889–90. We posit that in specific instances, development of immunological memory to an influenza virus strain in early life may lead to a dysregulated immune response to antigenically novel strains encountered in later life, thereby increasing the risk of death. Exposure during critical periods of development could also create holes in the T cell repertoire and impair fetal maturation in general, thereby increasing mortality from infectious diseases later in life. Knowledge of the age-pattern of susceptibility to mortality from influenza could improve crisis management during future influenza pandemics.

“The war is over – and I must go” Egon Schiele, 1890–1918.

     

Gene transfer to pre-hematopoietic and committed hematopoietic precursors in the early mouse Yolk Sac: a comparative study between <Emphasis Type="Italic">in situ</Emphasis> electroporation and retroviral transduction

Background  

Hematopoietic development in vertebrate embryos results from the sequential contribution of two pools of precursors independently generated. While intra-embryonic precursors harbour the features of hematopoietic stem cells (HSC), precursors formed earlier in the yolk sac (YS) display limited differentiation and self-renewal potentials. The mechanisms leading to the generation of the precursors in both sites are still largely unknown, as are the molecular basis underlying their different potential. A possible approach to assess the role of candidate genes is to transfer or modulate their expression/activity in both sites. We thus designed and compared transduction protocols to target either native extra-embryonic precursors, or hematopoietic precursors.