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51.
We are currently in an interesting phase of plant biotechnology releases, both for the scientists responsible for these innovations who are beginning to see their ideas realized, and for the biotechnology companies that are starting to see a return on their investment. One of the most notable examples, is the introduction of transgenic crops that are engineered to express a Bacillus thuringiensis toxin that confers resistance to insect predation. However, the picture is not altogether positive - there is concern that the introduction of this technology was premature or should not have happened at all, and that the valuable insecticidal properties of Bacillus thuringiensis will be lost. 相似文献
52.
Nishizono S Kusaba M Adan Y Imaizumi K 《Bioscience, biotechnology, and biochemistry》1999,63(2):379-383
A study was carried out to establish an animal model that would be suitable for evaluating the role of the diet in immune cell-mediated atherogenesis. Brown Norway rats were initially treated with hypervitamin D2 for 4 days and then fed on an atherogenic diet for 3 months, during which period the rats were either immunized with ovalubumin plus Al(OH)3 (OVA group) or with Al(OH)3 alone (control group) every 3 weeks. Aortic lesions were mainly composed of foam cells, the lesions evaluated by the intimal thickness of the ascending aorta being more severe in the OVA group than in the control group. The OVA group, in comparison with the control group, showed prominently increased serum levels of OVA-specific IgG and rat chymase, an indicator of mast cell degranulation. The intimal thickness was positively correlated with the level of chymase. Immunization had no effect on the serum lipid levels. These results support the hypothesis that mast cells play a role in the early stage of atherosclerosis and suggest that this animal model could be useful for evaluating the role of the diet in immune-related atherogenesis. 相似文献
53.
Adan Y Shibata K Ni W Tsuda Y Sato M Ikeda I Imaizumi K 《Bioscience, biotechnology, and biochemistry》1999,63(2):309-313
Apolipoprotein (apo) E-deficient mice were fed an atherogenic diet with either 1% ethyl ester docosahexaenoic acid (DHA) or safflower oil (SO) as a source of linoleic acid for 8 week. Both genders fed DHA had higher proportions of eicosapentaenoic acid and DHA, and lower proportions of linoleic and arachidonic acids in the liver and serum phospholipids than those fed SO. Males fed DHA had greater liver weight and tended to have higher concentrations of serum lipids and liver cholesterol than those fed SO, and there were opposite trends in females. Dietary fats and gender led to no significant effect on lesion sizes in aortic arch and thoracic plus abdominal aorta. These results indicate that the interactive action of sex-related factor(s) with dietary polyunsaturated fatty acids is involved in metabolic changes of serum lipids in apoE-deficient mice, and addition of DHA, compared with addition of SO, is not effective to abolish the atherosclerosis in this animal model. 相似文献
54.
Nijenhuis WA Garner KM van Rozen RJ Adan RA 《The Journal of biological chemistry》2003,278(25):22939-22945
The melanocortin-4 receptor (MC4R) plays an important role in the regulation of body weight in rodents. Mutations in the coding region of the MC4R are found more frequently in obese individuals, supporting the hypothesis that also in humans deficient melanocortin signaling may lead to obesity. Family studies that were carried out to demonstrate the relevance of single mutations for obesity were mostly inconclusive, most likely due to small sample size and complexity of the trait. In addition, the existing pharmacological data of the mutant receptors are limited in that for most mutations the effect on receptor expression level and Agouti-related protein (AgRP) pharmacology have not been studied. The aim of the present study was to gain further insight into the impact of the MC4R mutations on receptor function. Eleven missense mutations were tested for cell surface expression, affinity for alpha-melanocyte-stimulating hormone (alpha-MSH) and AgRP-(83-132), and the biological response to alpha-MSH. All mutants were poorly expressed at the cell surface, as measured by 125I-[Nle4-D-Phe7]alpha-MSH binding, and only a few mutants showed altered pharmacology for alpha-MSH and AgRP. Hemagglutinin-tagged mutant receptors were retained in the intracellular environment. These pharmacological data provide a basis to estimate the quantitative effect of MC4R mutations for the development of obesity. 相似文献
55.
56.
Amoresano A; Andolfo A; Siciliano RA; Mele A; Coscarella A; De Santis R; Mauro S; Pucci P; Marino G 《Glycobiology》1998,8(8):779-790
MEN 11300 is a hybrid glycoprotein of 297 amino acids obtained by fusion of
the cDNA encoding GM-CSF with the cDNA encoding EPO followed by
transfection of the hybrid gene into CHO cells. The oligonucleotide
construct incorporated a spacing sequence between the two individual cDNAs
which encodes eight amino acids constituting a linker peptide intended to
separate the GM-CSF and EPO moieties. The recombinant MEN 11300 protein was
submitted to a detailed structural characterization including the
verification of the entire amino acid sequence, the assignment of the
disulfide bridges pattern, the identification of the glycosylation sites
and the definition of the glycosidic moiety, including site-specificity.
Partial processing of the C-terminal Arg residue and the occurrence of
N-glycosylation sites at Asn27, Asn155, Asn169, Asn214 were established.
Moreover, O-glycosylation at Ser257 and at the N-terminal region was also
detected. A large heterogeneity was observed in the N-glycans due to the
presence of differently sialylated and fucosylated branched complex type
oligosaccharides whereas O-linked glycans were constituted by GalGalNAc
chains with a different number of sialic acids. The disulfide bridges
pattern was established by direct FABMS analysis of the proteolytic digests
or by ESMS analysis of HPLC purified fractions. Pairing of the eight
cysteine residues resulted in Cys54-Cys96, Cys88-Cys121, Cys138-Cys292, and
Cys160-Cys164. This S-S bridges pattern is identical to that occurring in
the individual natural GM-CSF and EPO, thus showing that the two protein
moieties in MEN 11300 can independently acquire their native
three-dimensional structure.
相似文献
57.
Unusual pattern of bacterial ice nucleation gene evolution 总被引:5,自引:0,他引:5
Edwards AR; Van den Bussche RA; Wichman HA; Orser CS 《Molecular biology and evolution》1994,11(6):911-920
Bacterial ice nucleation activity (INA+ phenotype) can be traced to the
product of a single gene, ina. A remarkably sparse distribution of this
phenotype within three bacterial genera indicates that the ina gene may
have followed an unusual evolutionary path. Southern blot analyses, coupled
with assays for ice-nucleating ability, revealed that within four bacterial
species an ina gene is present in some strains but absent from others.
Results of hybridization experiments using DNA fragments that flank the ina
gene suggested that the genotypic dimorphism of ina may be anomalous. A
phylogenetic analysis of 16S ribosomal RNA gene sequences from a total of
14 ina+ and ina- bacterial strains indicated that the ina+ bacteria are not
monophyletic but instead phylogenetically interspersed among ina- bacteria.
The relationships of ina+ bacteria inferred from ina sequence did not
coincide with those inferred from the 16S data. These results suggest the
possibility of horizontal transfer in the evolution of bacterial ina genes.
相似文献
58.
59.
Anastasiya Kuznetsova Gal Masrati Elena Vigonsky Nurit Livnat-Levanon Jessica Rose Moti Grupper Adan Baloum Janet G. Yang Douglas C. Rees Nir Ben-Tal Oded Lewinson 《The Journal of biological chemistry》2021,297(4)
All extant life forms require trace transition metals (e.g., Fe2/3+, Cu1/2+, and Mn2+) to survive. However, as these are environmentally scarce, organisms have evolved sophisticated metal uptake machineries. In bacteria, high-affinity import of transition metals is predominantly mediated by ABC transporters. During bacterial infection, sequestration of metal by the host further limits the availability of these ions, and accordingly, bacterial ABC transporters (importers) of metals are key virulence determinants. However, the structure–function relationships of these metal transporters have not been fully elucidated. Here, we used metal-sensitivity assays, advanced structural modeling, and enzymatic assays to study the ABC transporter MntBC-A, a virulence determinant of the bacterial human pathogen Bacillus anthracis. We find that despite its broad metal-recognition profile, MntBC-A imports only manganese, whereas zinc can function as a high-affinity inhibitor of MntBC-A. Computational analysis shows that the transmembrane metal permeation pathway is lined with six titratable residues that can coordinate the positively charged metal, and mutagenesis studies show that they are essential for manganese transport. Modeling suggests that access to these titratable residues is blocked by a ladder of hydrophobic residues, and ATP-driven conformational changes open and close this hydrophobic seal to permit metal binding and release. The conservation of this arrangement of titratable and hydrophobic residues among ABC transporters of transition metals suggests a common mechanism. These findings advance our understanding of transmembrane metal recognition and permeation and may aid the design and development of novel antibacterial agents. 相似文献
60.