This work is concerned with the optimization study of the semibatch fermentation by which an amino acid is produced. The particular fermentation studied is the synthesis of lysine by the auxotrophic mutant. Applying Green's theorem to the maximization problem was proposed, and it succeeded in determining the feed rate of the substrate that maximized the production rate of the desired product. 相似文献
A fourth type of rat phosphoinositide-specific phospholipase C (PLC IV) has been cloned for cDNA and sequenced. PLC IV is distinct from the other three types of rat PLC (PLC I, II, and III) with respect to primary structure and tissue distribution of its mRNAs. PLC IV contains two homologous regions included commonly in PLC I, II, and III and is most similar to PLC II (identity: 50.2%). PLC IV, in common with PLC II, has a sequence homologous to the N-terminal regulatory domains of nonreceptor tyrosine kinases of the src-family of oncogenes. Using an Escherichia coli expression system, we succeeded in producing active PLC IV in E. coli crude extracts. Various truncation experiments of the PLC IV cDNA revealed that the src-related domain is not necessary for catalytic activity while both domains homologous among PLC I-IV are essential. PLC IV is expressed in various rat tissues and abundant in spleen, suggesting that PLC IV plays a fundamental role in cellular functions such as growth and secretion. 相似文献
To characterize Fe homeostasis during the early stages of seed germination, a microarray analysis was performed. mRNAs extracted
from fully mature seeds or seeds harvested 1–3 days after sowing were hybridized to a rice microarray containing approximately
22,000 cDNA oligo probes. Many Fe deficiency-inducible genes were strongly expressed throughout early seed germination. These
results suggest that the demand for Fe is extremely high during germination.
Under Fe-deficient conditions, rice produces and secretes a metal-cation chelator called deoxymugineic acid (DMA) to acquire
Fe from the soil. In addition, DMA and its intermediate nicotianamine (NA) are thought to be involved in long distance Fe
transport in rice. Using promoter-β-glucuronidase (GUS) analysis, we investigated the expression patterns during seed germination
of the Fe deficiency-inducible genes OsNAS1, OsNAS2, OsNAS3, OsNAAT1, and OsDMAS1, which encode enzymes that participate in the biosynthesis of DMA, and the transporter genes OsYSL2 and OsIRT1, which are involved in Fe transport. All of these genes were expressed in germinating seeds prior to protrusion of the radicle.
These results suggest that DMA and NA are produced and involved in Fe transport during germination.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
Species delimitations by morphological and by genetic markers are not always congruent. Magnolia kobus consists of two morphologically different varieties, kobus and borealis. The latter variety is characterized by larger leaves than the former. For the conservation of M. kobus genetic resources in natural forests, the relationships between morphological and genetic variation should be clarified. We investigated variations in nuclear microsatellites, chloroplast DNA (cpDNA) sequences and leaf morphological traits in 23 populations of M. kobus over the range of species. Two genetically divergent lineages, northern and southern were detected and their geographical boundary was estimated to be at 39°N. The northern lineage consisted of two genetic clusters and a single cpDNA haplotype, while the southern one had multiple genetic clusters and cpDNA haplotypes. The northern lineage showed significantly lower genetic diversity than the southern. Approximate Bayesian computation indicated that the northern and southern lineages had experienced, respectively, population expansion and long-term stable population size. The divergence time between the two lineages was estimated to be 565,000 years ago and no signature of migration between the two lineages after divergence was detected. Ecological niche modeling showed that the potential distribution area in northern Japan at the last glacial maximum was very small. It is thus considered that the two lineages have experienced different population histories over several glacial-inter-glacial cycles. Individuals of populations in the central to northern part of Honshu on the Sea of Japan side and in Hokkaido had large leaf width and area. These leaf characteristics corresponded with those of variety borealis. However, the delimitation of the northern and southern lineages detected by genetic markers (39°N) was not congruent with that detected by leaf morphologies (36°N). It is therefore suggested that variety borealis is not supported genetically and the northern and southern lineages should be considered separately when identifying conservation units based not on morphology but on genetic markers.
Effects of taurine or γ-aminobutyric acid (GABA) on akinesia and analgesia induced by D-Ala2-Met-enkephalinamide were investigated in rats. Administration of taurine (dose range: 2.375×10?2 M–9.5×10?2 M/10 μl) into the left lateral ventricle 10 min prior to the injection of D-Ala2-Met-enkephalinamide (50 μg/10 μl) produced a dose-dependent reduction in the duration of akinesia and to some extent of analgesia, as estimated at 30 min and 60 min following the enkephalinamide injection; at the first estimation-time (10 min), taurine did not alter the duration of akinesia or that of analgesia. The median effective dose (ED50) for akinesia determined at 60 min after D-Ala2-Met-enkephalinamide was 5 times greater and that for analgesia assessed at the same time was 1.7 times greater in taurine-treated rats than the respective doses in control animals. Administration of GABA under similar experimental conditions produced a dose-dependent reduction in the duration of analgesia from the initial estimation time (10 min) following the injection of D-Ala2-Met-enkephalinamide. The ED50 for analgesia determined at 30 min after D-Ala2-Met-enkephalinamide was 3 times greater in GABA-treated rats than in control animals. Unlike the effects of taurine, GABA did not alter the duration of akinesia. Neither the duration of akinesia nor that of analgesia was modified by taurine or GABA alone in rats tested 9 min after the injection of each amino acid. These findings suggest that taurine may promote a recovery from both akinesia and analgesia, while GABA decreases only the analgesia induced by D-Ala2-Met-enkephalinamide. 相似文献