scholarly journals Neonatal testis growth recreated in vitro by two-dimensional organ spreading

2018 ◽  
Vol 115 (12) ◽  
pp. 3030-3041 ◽  
Author(s):  
Kazuaki Kojima ◽  
Hiroko Nakamura ◽  
Mitsuru Komeya ◽  
Hiroyuki Yamanaka ◽  
Yoshinori Makino ◽  
...  
Author(s):  
U. Aebi ◽  
L.E. Buhle ◽  
W.E. Fowler

Many important supramolecular structures such as filaments, microtubules, virus capsids and certain membrane proteins and bacterial cell walls exist as ordered polymers or two-dimensional crystalline arrays in vivo. In several instances it has been possible to induce soluble proteins to form ordered polymers or two-dimensional crystalline arrays in vitro. In both cases a combination of electron microscopy of negatively stained specimens with analog or digital image processing techniques has proven extremely useful for elucidating the molecular and supramolecular organization of the constituent proteins. However from the reconstructed stain exclusion patterns it is often difficult to identify distinct stain excluding regions with specific protein subunits. To this end it has been demonstrated that in some cases this ambiguity can be resolved by a combination of stoichiometric labeling of the ordered structures with subunit-specific antibody fragments (e.g. Fab) and image processing of the electron micrographs recorded from labeled and unlabeled structures.


1988 ◽  
Vol 252 (2) ◽  
pp. 607-615 ◽  
Author(s):  
J M Tavaré ◽  
R M Denton

1. A partially purified preparation of human placental insulin receptors was incubated with [gamma-32P]ATP in the presence or absence of insulin. The 32P-labelled insulin-receptor beta-subunits were then isolated, cleaved with trypsin followed by protease V8 and the [32P]phosphopeptides generated were analysed by thin layer electrophoresis and chromatography. This approach revealed that insulin stimulates autophosphorylation of the insulin-receptor beta-subunit in vitro on at least seven tyrosine residues distributed among three distinct domains. 2. One domain (domain 2), containing tyrosine residues 1146, 1150 and 1151 was the most rapidly phosphorylated and could be recovered as mono-, di- and triphosphorylated peptides cleaved by trypsin at Arg-1143 and either Lys-1153 or Lys-1156. Multiple phosphorylation of this domain appears to partially inhibit the cleavage at Lys-1153 by trypsin. 3. In a second domain (domain 3) containing two phosphorylated tyrosine residues at positions 1316 and 1322 the tyrosines were phosphorylated more slowly than those in domain 2. This domain is close to the C-terminus of the beta-subunit polypeptide chain. 4. At least two further tyrosine residues appeared to be phosphorylated after those in domains 2 and 3. These residues probably residue within a domain lying in close proximity to the inner face of the plasma membrane containing tyrosines 953, 960 and 972, but conclusive evidence is still required. 5. The two-dimensional thin-layer analysis employed in this study to investigate insulin-receptor phosphorylation has several advantages over previous methods based on reverse-phase chromatography. It allows greater resolution of 32P-labelled tryptic peptides and, when coupled to radioautography, is considerably more sensitive. The approach can be readily adapted to study phosphorylation of the insulin receptor within intact cells.


1993 ◽  
Vol 106 (1) ◽  
pp. 209-218 ◽  
Author(s):  
S.W. James ◽  
C.D. Silflow ◽  
P. Stroom ◽  
P.A. Lefebvre

A mutation in the alpha 1-tubulin gene of Chlamydomonas reinhardtii was isolated by using the amiprophos-methyl-resistant mutation apm1-18 as a background to select new mutants that showed increased resistance to the drug. The upA12 mutation caused twofold resistance to amiprophos-methyl and oryzalin, and twofold hypersensitivity to the microtubule-stabilizing drug taxol, suggesting that the mutation enhanced microtubule stability. The resistance mutation was semi-dominant and mapped to the same interval on linkage group III as the alpha 1-tubulin gene. Two-dimensional gel immunoblots of proteins in the mutant cells revealed two electrophoretically altered alpha-tubulin isoforms, one of which was acetylated and incorporated into microtubules in the axoneme. The mutant isoforms co-segregated with the drug-resistance phenotypes when mutant upA12 was backcrossed to wild-type cells. Two-dimensional gel analysis of in vitro translation products showed that the non-acetylated variant alpha-tubulin was a primary gene product. DNA sequence analysis of the alpha 1-tubulin genes from mutant and wild-type cells revealed a single missense mutation, which predicted a change in codon 24 from tyrosine in wild type to histidine in mutant upA12. This alteration in the predicted amino acid sequence corroborated the approximately +1 basic charge shift observed for the variant alpha-tubulins. The mutant allele of the alpha 1-tubulin gene was designated tua1-1.


Author(s):  
Lila Bazina ◽  
Dimitrios Bitounis ◽  
Xiaoqiong Cao ◽  
Glen M. DeLoid ◽  
Dorsa Parviz ◽  
...  

Background: engineered nanomaterials (ENMs) have already made their way into myriad applications and products across multiple industries.


Development ◽  
1963 ◽  
Vol 11 (1) ◽  
pp. 135-154
Author(s):  
K. W. Jones ◽  
T. R. Elsdale

A Common procedure in amphibian embryology has been to remove portions from embryos and culture these under conditions in which the large numbers of cells retain a close-knit association, favourable to the differentiation of primitive organs in the explant. It has not, in general, been the aim to employ the primary explant as a source of a two-dimensional outgrowth of cells on the substrate, as in typical cell culture procedures. Because of their inherent migratory tendencies, however, outgrowths of pigment cells are readily obtained from explants of the amphibian neural crest, and these have stimulated the interest of a number of investigators (see Wilde, 1961). Holtfreter (1938, 1946) and Finnegan (1953) have also observed the migration of cells from explants of Urodele embryos. Several investigators have employed cell cultures as opposed to organ type cultures in induction studies, Niu & Twitty (1953), Niu (1958), Barth & Barth (1959) and Becker, Tiedemann & Tiedemann (1959).


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