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171.
Cell therapy has achieved tremendous success in regenerative medicine in the past several decades. However, challenges such as cell loss, death and immune-rejection after transplantation still persist. Biomaterials have been designed as carriers to deliver cells to desirable region for local tissue regeneration; as barriers to protect transplanted cells from host immune attack; or as reactors to stimulate host cell recruitment, homing and differentiation. With the assistance of biomaterials, improvement in treatment efficiency has been demonstrated in numerous animal models of degenerative diseases compared with routine free cell-based therapy. Emerging clinical applications of biomaterial assisted cell therapies further highlight their great promise in regenerative therapy and even cure for complex diseases, which have been failed to realize by conventional therapeutic approaches. 相似文献
172.
氢气是一种新型的清洁高效能源,制氢技术的创新是目前研究的热点。将新型的技术及材料应用到生物制氢工艺中,从而促进生物制氢技术的产氢效率和工程应用是研究的重点之一。该文阐述了光合细菌在固定化生长条件下发酵产氢的最新研究进展,从固定化技术的原理、固定化方法的应用进展及影响因素几个方面进行了综述,详细阐述了包括包埋、悬浮载体附着生长及固定生物膜法等几种固定化方法对光发酵产氢的作用,介绍了国内外用于固定化的新型材料,并对今后的研究重点及方向进行了展望。 相似文献
173.
174.
Different species of Paenibacillus are considered to be plant growth-promoting rhizobacteria (PGPR) due to their ability to repress soil borne pathogens, fix atmospheric nitrogen, induce plant resistance to diseases and/or produce plant growth-regulating substances such as auxins. Although it is known that indole-3-acetic acid (IAA) is the primary naturally occurring auxin excreted by Paenibacillus species, its transport mechanisms (auxin efflux carriers) have not yet been characterized. In this study, the auxin production of P. polymyxa and P. graminis, which are prevalent in the rhizospheres of maize and sorghum sown in Brazil, was evaluated. In addition, the gene encoding the Auxin Efflux Carrier (AEC) protein from P. polymyxa DSM36(T) was sequenced and used to determine if various strains of P. polymyxa and P. graminis possessed this gene. Each of the 68 P. polymyxa strains evaluated in this study was able to produce IAA, which was produced at concentrations varying from 1 to 17 microg/ml. However, auxin production was not detected in any of the 13 P. graminis strains tested in this study. Different primers were designed for the PCR amplification of the gene coding for the AEC in P. polymyxa, and the predicted protein of 319 aa was homologous to AEC from Bacillus amyloliquefaciens, B. licheniformis, and B. subtilis. However, no product was observed when these primers were used to amplify the genomic DNA of seven strains of P. graminis, which suggests that this gene is not present in this species. Moreover, none of the P. graminis genomes tested were homologous to the gene coding for AEC, whereas all of the P. polymyxa genomes evaluated were. This is the first study to demonstrate that the AEC protein is present in P. polymyxa genome. 相似文献
175.
María del Rocío Oliveros-Valenzuela David Reyes Jos Snchez-Bravo Manuel Acosta Carlos Nicols 《Plant Physiology and Biochemistry》2008,46(12):1071-1076
Polar auxin transport (PAT) is necessary for the formation of adventitious roots in the base of leafy stem cuttings, as has been demonstrated in several studies in which the application of PAT inhibitors strongly inhibited the rooting of cuttings. However, unlike in the case of lateral roots, there is almost no information on the molecular mechanism that controls PAT in the formation of adventitious roots. A novel cDNA encoding an auxin influx carrier has been isolated and characterized from carnation (Dianthus caryophyllus) cuttings. The full length of DcAUX1 was obtained and the deduced aminoacid sequence revealed a high degree of identity with the corresponding auxin carrier proteins from several species. The expression of this gene depended on the organ, the carnation cultivar and the length of time cuttings had been stored in a cold chamber. As a rule, expression was higher in stem than in leaves, in the basal than in the first internode and in mature than in young leaves irrespective of the cultivar and the duration of the storage. This pattern of expression agrees with the results of a previous study showing that auxin from mature leaves was essential for rooting, while exogenous auxin applied to mature leaves was polarly transported in the stem and accumulated in the basal internode (the rooting zone). Variations in the expression observed during storage (depending of the cultivar) might be related to the variation in PAT and rooting reported in previous studies. 相似文献
176.
Menkes syndrome is an X-linked, fatal neurodegenerative disorder of copper metabolism, caused by mutations in the ATP7A gene, encoding a copper-transporting P1B-type ATPase. To date, a total of approximately 160 different mutations have been reported worldwide. The clinical phenotypes observed in these patients include progressive neuro-degeneration, connective-tissue abnormalities and peculiar hair. There is phenotypic variability. While the majority of the patients do not survive early childhood, milder cases leading to longer survival have been reported. In this review we focus on mutations, identified in patients with milder forms of Menkes disease, and discuss the possibility of establishing a genotype–phenotype correlation. The presence of small amounts of normal protein, or the presence of partly functional protein variants containing a less essential amino acid substitution or a truncation of the N- or C-terminus, might all result in a milder, atypical phenotype. A clear phenotype–genotype correlation is however difficult to establish, clearly illustrated by the presence of inter- and even intra-familial variability. 相似文献
177.
Guang-Rong Zhao Ting Luo Yong-Jin Zhou Xin Jiang Bin Qiao Feng-Ming Yu Ying-Jin Yuan 《Applied microbiology and biotechnology》2009,83(2):305-313
Streptolydigin, a secondary metabolite produced by Streptomyces lydicus, is a potent inhibitor of bacterial RNA polymerases. It has been suggested that streptolydigin biosynthesis is associated
with polyketide synthase (PKS) and nonribosomal peptide synthetase (NRPS). Thus, there is great interest in understanding
the role of fatty acid biosynthesis in the biosynthesis of streptolydigin. In this paper, we cloned a type II fatty acid synthase
(FAS II) gene cluster of fabDHCF from the genome of S. lydicus and constructed the SlyfabCF-disrupted mutant. Sequence analysis showed that SlyfabDHCF is 3.7 kb in length and encodes four separated proteins with conserved motifs and active residues, as shown in the FAS II
of other bacteria. The SlyfabCF disruption inhibited streptolydigin biosynthesis and retarded mycelial growth, which were likely caused by the inhibition
of fatty acid synthesis. Streptolydigin was not detected in the culture of the mutant strain by liquid chromatography–mass
spectrometry. Meanwhile, the streptolol moiety of streptolydigin accumulated in cultures. As encoded by fabCF, acyl carrier protein (ACP) and β-ketoacyl-ACP synthase II are required for streptolydigin biosynthesis and likely involved
in the step between PKS and NRPS. Our results provide the first genetic and metabolic evidence that SlyfabCF is shared by fatty acid synthesis and antibiotic streptolydigin synthesis. 相似文献
178.
QTL for resistance to Salmonella carrier state confirmed in both experimental and commercial chicken lines 总被引:1,自引:0,他引:1
F. Calenge F. Lecerf J. Demars K. Feve F. Vignoles F. Pitel A. Vignal P. Velge N. Sellier C. Beaumont 《Animal genetics》2009,40(5):590-597
The ability of chickens to carry Salmonella without displaying disease symptoms is responsible for Salmonella propagation in poultry stocks and for subsequent human contamination through the consumption of contaminated eggs or meat. The selection of animals more resistant to carrier state might be a way to decrease the propagation of Salmonella in poultry stocks and its transmission to humans. Five QTL controlling variation for resistance to carrier state in a chicken F2 progeny derived from the White Leghorn inbred lines N and 61 had been previously identified using a selective genotyping approach. Here, a second analysis on the whole progeny was performed, which led to the confirmation of two QTL on chromosomes 2 and 16. To assess the utility of these genomic regions for selection in commercial lines, we tested them together with other QTL identified in an [N×61 ] × N backcross progeny and with the candidate genes SLC11A1 and TLR4 . We used a commercial line divergently selected for either low or high carrier-state resistance both in young chicks and in adult hens. In divergent chick lines, one QTL on chromosome 1 and one in the SLC11A1 region were significantly associated with carrier-state resistance variations; in divergent adult lines, one QTL located in the major histocompatibility complex on chromosome 16 and one in the SLC11A1 region were involved in these variations. Genetic studies conducted on experimental lines can therefore be of potential interest for marker-assisted selection in commercial lines. 相似文献
179.
This study focuses on the effect of the initial quaternary structure of bovine hemoglobin (Hb) on the physical properties of glutaraldehyde polymerized Hb (PolyHb) solutions. Tense (T) state PolyHb was synthesized by maintaining the pO2 of Hb before and after polymerization at 0 mm Hg. In contrast, relaxed (R) state PolyHb was generated by maintaining the pO2 of Hb before and after polymerization to >749 mm Hg. PolyHb solutions were characterized by measuring the pO2, methemoglobin (metHb) level, molecular weight distribution, O2 affinity and cooperativity coefficient. The metHb level of all PolyHb solutions was low (<2%). Analysis of the molecular weight distribution of PolyHb solutions indicates that in general, the molecular weight of PolyHb solutions increased with increasing cross‐link density. T‐state PolyHb solutions exhibited lower O2 affinity compared to unmodified Hb, whereas R‐state PolyHb solutions exhibited higher O2 affinity compared to unmodified Hb. In addition, the polymerization reaction resulted in a significant decrease in cooperativity that was more pronounced at higher cross‐link densities. All of these results were explained in terms of the quaternary structure of Hb. Taken together, our results yield more insight into the importance Hb's quaternary structure plays in defining the physical properties of glutaraldehyde PolyHb solutions. This information will be useful in designing optimized glutaraldehyde PolyHb oxygen carriers for various applications in transfusion medicine. © 2009 American Institute of Chemical Engineers Biotechnol. Prog. 2009 相似文献
180.