29 research outputs found
Dynamics of gelling liquids: a short survey
The dynamics of randomly crosslinked liquids is addressed via a Rouse- and a
Zimm-type model with crosslink statistics taken either from bond percolation or
Erdoes-Renyi random graphs. While the Rouse-type model isolates the effects of
the random connectivity on the dynamics of molecular clusters, the Zimm-type
model also accounts for hydrodynamic interactions on a preaveraged level. The
incoherent intermediate scattering function is computed in thermal equilibrium,
its critical behaviour near the sol-gel transition is analysed and related to
the scaling of cluster diffusion constants at the critical point. Second,
non-equilibrium dynamics is studied by looking at stress relaxation in a simple
shear flow. Anomalous stress relaxation and critical rheological properties are
derived. Some of the results contradict long-standing scaling arguments, which
are shown to be flawed by inconsistencies.Comment: 21 pages, 3 figures; Dedicated to Lothar Schaefer on the occasion of
his 60th birthday; Changes: added comments on the gel phase and some
reference
Environmental signals rather than layered ontogeny imprint the function of type 2 conventional dendritic cells in young and adult mice
Conventional dendritic cells (cDC) are key activators of naive T cells, and can be targeted in adults to induce adaptive immunity, but in early life are considered under-developed or functionally immature. Here we show that, in early life, when the immune system develops, cDC2 exhibit a dual hematopoietic origin and, like other myeloid and lymphoid cells, develop in waves. Developmentally distinct cDC2 in early life, despite being distinguishable by fate mapping, are transcriptionally and functionally similar. cDC2 in early and adult life, however, are exposed to distinct cytokine environments that shape their transcriptional profile and alter their ability to sense pathogens, secrete cytokines and polarize T cells. We further show that cDC2 in early life, despite being distinct from cDC2 in adult life, are functionally competent and can induce T cell responses. Our results thus highlight the potential of harnessing cDC2 for boosting immunity in early life.</p
Consensus structure and evolution of 5S rRNA.
A consensus structure model of 5S rRNA presenting all conserved nucleotides in fixed positions has been deduced from the primary and secondary structure of 71 eubacterial, archaebacterial, eukaryotic cytosolic and organellar molecules. Phylogenetically related groups of molecules are characterized by nucleotide deletions in helices III, IV and V, and by potential base pair interactions in helix IV. The group-specific deletions are correlated with the early branching pattern of a dendrogram calculated from nucleotide substitution data: the first major division separates the group of eubacterial and organellar molecules from a second group containing the common ancestors of archaebacterial and eukaryotic/cytosolic molecules. The earliest diverging branch of the eubacterial/organellar group includes molecules from Thermus thermophilus, T. aquaticus, Rhodospirillum rubrum, Paracoccus denitrificans and wheat mitochondria
Nucleotide sequence of 5S ribosomal RNA from Aspergillus nidulans and Neurospora crassa.
The nucleotide sequences of 5S rRNA molecules isolated from the cytosol and the mitochondria of the ascomycetes A. nidulans and N. crassa were determined by partial chemical cleavage of 3'-terminally labelled RNA. The sequence identity of the cytosolic and mitochondrial RNA preparations confirms the absence of mitochondrion-specific 5S rRNA in these fungi. The sequences of the two organisms differ in 35 positions, and each sequence differs from yeast 5S rRNA in 44 positions. Both molecules contain the sequence GCUC in place of GAAC or GAUY found in all other 5S rRNAs, indicating that this region is not universally involved in base-pairing to the invariant GTpsiC sequence of tRNAs