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21.
Mikhail Geyfman Maksim V. Plikus Elsa Treffeisen Bogi Andersen Ralf Paus 《Biological reviews of the Cambridge Philosophical Society》2015,90(4):1179-1196
The hair follicle (HF) represents a prototypic ectodermal–mesodermal interaction system in which central questions of modern biology can be studied. A unique feature of these stem‐cell‐rich mini‐organs is that they undergo life‐long, cyclic transformations between stages of active regeneration (anagen), apoptotic involution (catagen), and relative proliferative quiescence (telogen). Due to the low proliferation rate and small size of the HF during telogen, this stage was conventionally thought of as a stage of dormancy. However, multiple lines of newly emerging evidence show that HFs during telogen are anything but dormant. Here, we emphasize that telogen is a highly energy‐efficient default state of the mammalian coat, whose function centres around maintenance of the hair fibre and prompt responses to its loss. While actively retaining hair fibres with minimal energy expenditure, telogen HFs can launch a new regeneration cycle in response to a variety of stimuli originating in their autonomous micro‐environment (including its stem cell niche) as well as in their external tissue macro‐environment. Regenerative responses of telogen HFs change as a function of time and can be divided into two sub‐stages: early ‘refractory’ and late ‘competent’ telogen. These changing activities are reflected in hundreds of dynamically regulated genes in telogen skin, possibly aimed at establishing a fast response‐signalling environment to trauma and other disturbances of skin homeostasis. Furthermore, telogen is an interpreter of circadian output in the timing of anagen initiation and the key stage during which the subsequent organ regeneration (anagen) is actively prepared by suppressing molecular brakes on hair growth while activating pro‐regenerative signals. Thus, telogen may serve as an excellent model system for dissecting signalling and cellular interactions that precede the active ‘regenerative mode’ of tissue remodeling. This revised understanding of telogen biology also points to intriguing new therapeutic avenues in the management of common human hair growth disorders. 相似文献
22.
SE?Aleshin AV?Timofeev MV?Khoretonenko LG?Zakharova GV?Pashvykina JR?Stephenson AM?Shneider AD?AltsteinEmail author 《BMC microbiology》2005,5(1):45
Background
Heterologous prime-boost immunization protocols using different gene expression systems have proven to be successful tools in protecting against various diseases in experimental animal models. The main reason for using this approach is to exploit the ability of expression cassettes to prime or boost the immune system in different ways during vaccination procedures. The purpose of the project was to study the ability of recombinant vaccinia virus (VV) and bacterial plasmid, both carrying the NS1 gene from tick-borne encephalitis (TBE) virus under the control of different promoters, to protect mice against lethal challenge using a heterologous prime-boost vaccination protocol. 相似文献23.
Morphoregulation of teeth: modulating the number, size, shape and differentiation by tuning Bmp activity 总被引:1,自引:0,他引:1
Plikus MV Zeichner-David M Mayer JA Reyna J Bringas P Thewissen JG Snead ML Chai Y Chuong CM 《Evolution & development》2005,7(5):440-457
During development and evolution, the morphology of ectodermal organs can be modulated so that an organism can adapt to different environments. We have proposed that morphoregulation can be achieved by simply tilting the balance of molecular activity. We test the principles by analyzing the effects of partial downregulation of Bmp signaling in oral and dental epithelia of the keratin 14-Noggin transgenic mouse. We observed a wide spectrum of tooth phenotypes. The dental formula changed from 1.0.0.3/1.0.0.3 to 1.0.0.2(1)/1.0.0.0. All mandibular and M3 maxillary molars were selectively lost because of the developmental block at the early bud stage. First and second maxillary molars were reduced in size, exhibited altered crown patterns, and failed to form multiple roots. In these mice, incisors were not transformed into molars. Histogenesis and differentiation of ameloblasts and odontoblasts in molars and incisors were abnormal. Lack of enamel caused misocclusion of incisors, leading to deformation and enlargement in size. Therefore, subtle differences in the level, distribution, and timing of signaling molecules can have major morphoregulatory consequences. Modulation of Bmp signaling exemplifies morphoregulation hypothesis: simple alteration of key signaling pathways can be used to transform a prototypical conical-shaped tooth into one with complex morphology. The involvement of related pathways and the implication of morphoregulation in tooth evolution are discussed. 相似文献
24.
25.
Background
Some diseases, like tumors, can be related to chromosomal aberrations, leading to changes of DNA copy number. The copy number of an aberrant genome can be represented as a piecewise constant function, since it can exhibit regions of deletions or gains. Instead, in a healthy cell the copy number is two because we inherit one copy of each chromosome from each our parents. 相似文献26.
C Nageswara Raju S Sailaja S Pavan Kumari SJ Dhoble V Ramesh Kumar MV Ramanaiah B Sudhakar Reddy 《Luminescence》2013,28(2):162-168
This article reports on the optical properties of 0.5% mol of Sm3+, Dy3+ ion‐doped B2O3‐TeO2‐Li2O‐AlF3 (LiAlFBT) glasses. The glass samples were characterized by optical absorption and emission spectra. Judd‐Ofelt theory was applied to analyze the optical absorption spectra and calculate the intensity parameters and radiative properties of the emission transitions. The emission spectra of Sm3+ and Dy3+:LiAlFBT glasses showed a bright reddish‐orange emission at 598 nm (4G5/2 → 6H7/2) and an intense yellow emission at 574 nm (4F9/2 → 6H13/2), respectively. Full width at half maximum (FWHM), stimulated emission cross section, gain bandwidth and optical gain values were also calculated to extend the applications of the Sm3+ and Dy3+:LiAlFBT glasses. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
27.
28.
Tobias Wauer Kirby N Swatek Jane L Wagstaff Christina Gladkova Jonathan N Pruneda Martin A Michel Malte Gersch Christopher M Johnson Stefan MV Freund David Komander 《The EMBO journal》2015,34(3):307-325
The protein kinase PINK1 was recently shown to phosphorylate ubiquitin (Ub) on Ser65, and phosphoUb activates the E3 ligase Parkin allosterically. Here, we show that PINK1 can phosphorylate every Ub in Ub chains. Moreover, Ser65 phosphorylation alters Ub structure, generating two conformations in solution. A crystal structure of the major conformation resembles Ub but has altered surface properties. NMR reveals a second phosphoUb conformation in which β5-strand slippage retracts the C-terminal tail by two residues into the Ub core. We further show that phosphoUb has no effect on E1-mediated E2 charging but can affect discharging of E2 enzymes to form polyUb chains. Notably, UBE2R1- (CDC34), UBE2N/UBE2V1- (UBC13/UEV1A), TRAF6- and HOIP-mediated chain assembly is inhibited by phosphoUb. While Lys63-linked poly-phosphoUb is recognized by the TAB2 NZF Ub binding domain (UBD), 10 out of 12 deubiquitinases (DUBs), including USP8, USP15 and USP30, are impaired in hydrolyzing phosphoUb chains. Hence, Ub phosphorylation has repercussions for ubiquitination and deubiquitination cascades beyond Parkin activation and may provide an independent layer of regulation in the Ub system. 相似文献
29.
Optimization of mycophenolic acid production in solid state fermentation using response surface methodology 总被引:7,自引:0,他引:7
A K Sadhukhan MV Ramana Murthy R Ajaya Kumar E V S Mohan G Vandana C Bhar K Venkateswara Rao 《Journal of industrial microbiology & biotechnology》1999,22(1):33-38
Mycophenolic acid (MPA) can be produced in solid state fermentation. An isolate of Penicillium brevi-compactum ATCC 16024 grown on moist wheat bran produced a titre of 425 mg per kg of wheat bran. Central composite rotatable design
and response surface methodology were employed to derive a statistical model for media optimization towards production of
mycophenolic acid. Five levels with a five factorial design were adopted. The correlation coefficient was 0.82, ensuring a
satisfactory adjustment of the model to the experimental values. This statistical design was very effective in improving the
titre of mycophenolic acid up to 3286 mg per kg of wheat bran.
Received 24 July 1998/ Accepted in revised form 4 December 1998 相似文献
30.
Sheila C Rahal Reinaldo S Volpi Carlos R Teixeira Vania MV Machado Guilherme DP Soares Carlos Ramires Neto Kathleen Linn 《BMC veterinary research》2012,8(1):1-5