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Summary In situ gelation of alginate, in which Ca-ions are liberated internally in the gel, was used for immobilization of yeast cells. Compared to the traditional alginate gelation method, internal gelling gave immobilized yeast particles of higher strength, without reduction in fermentation rate. 相似文献
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Y Mori S Seino K Takeda I L Flink Y Murata G I Bell S Refetoff 《Molecular endocrinology (Baltimore, Md.)》1989,3(3):575-579
T4-binding globulin (TBG), a 54-kilodalton glycoprotein, is the major thyroid hormone transport protein in man. The exact nature of the mutations causing X chromosome-linked TBG deficiency, which affect about 1 in 2,500 newborn males, is unknown. Here we report the sequence of a unique variant TBG (TBG-Gary) encoding a protein with severely impaired T4 binding as well as decreased stability at 37 C, resulting in its rapid in vivo denaturation. A single nucleotide substitution in the codon for residue 96 of the mature protein replaces isoleucine with asparagine; this replacement creates an additional site for N-linked glycosylation. The anodal shift of TBG-Gary on isoelectric focusing gel electrophoresis suggests that this new site is likely glycosylated. Since glycosylated is required for TBG to assume its correct tertiary structure, but is not subsequently necessary for maintenance of the biological properties or stability of the molecule, we believe that the likely presence of additional carbohydrate probably affects a higher order structure of the molecule and is thus responsible for the reduced stability and hormone binding activity of TBG-Gary (TBGASN-96). 相似文献
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The phylogeny of Greya Busck (Lepidoptera: Prodoxidae) was inferred from
nucleotide sequence variation across a 765-bp region in the cytochrome
oxidase I and II genes of the mitochondrial genome. Most parsimonious
relationships of 25 haplotypes from 16 Greya species and two outgroup
genera (Tetragma and Prodoxus) showed substantial congruence with the
species relationships indicated by morphological variation. Differences
between mitochondrial and morphological trees were found primarily in the
positions of two species, G. variabilis and G. pectinifera, and in the
branching order of the three major species groups in the genus. Conflicts
between the data sets were examined by comparing levels of homoplasy in
characters supporting alternative hypotheses. The phylogeny of Greya
species suggests that host-plant association at the family level and larval
feeding mode are conservative characters. Transition/transversion ratios
estimated by reconstruction of nucleotide substitutions on the phylogeny
had a range of 2.0-9.3, when different subsets of the phylogeny were used.
The decline of this ratio with the increase in maximum sequence divergence
among taxa indicates that transitions are masked by transversions along
deeper internodes or long branches of the phylogeny. Among transitions,
substitutions of A-->G and T-->C outnumbered their reciprocal
substitutions by 2-6 times, presumably because of the approximately 4:1
(77%) A+T-bias in nucleotide base composition. Of all transversions,
73%-80% were A<-->T substitutions, 85% of which occurred at third
positions of codons; these estimates did not decrease with an increase in
maximum sequence divergence of taxa included in the analysis. The high
frequency of A<-->T substitutions is either a reflection or an
explanation of the 92% A+T bias at third codon positions.
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