Polyphenol oxidase (PPO) activity in potato (Solanum tuberosum) plants was high in stolons, tubers, roots, and flowers but low in leaves and stems. PPO activity per tuber continued to increase throughout tuber development but was highest on a fresh weight basis in developing tubers. PPO activity was greatest at the tuber exterior, including the skin and cortex tissue 1 to 2 mm beneath the skin. Flowers had high PPO activity throughout development, particularly in the anthers and ovary. Five distinct cDNA clones encoding PPO were isolated from developing tuber RNA. POT32 was the major form expressed in tubers and was found in all parts of the tuber and at all stages of tuber development. It was also expressed in roots but not in photosynthetic tissues. POT33 was expressed in tubers but mainly in the tissue near the skin. POT72 was detected in roots and at low levels in developing tubers. NOR333 was identical with the P2 PPO clone previously isolated from potato leaves (M.D. Hunt, N.T. Eannetta, Y. Haifeng, S.M. Newman, J.C. Steffens [1993] Plant Mol Biol 21: 59-68) and was detected in young leaves and in tissue near the tuber skin but was highly expressed in flowers. The results indicate that PPO is present as a small multigene family in potato and that each gene has a specific temporal and spatial pattern of expression. 相似文献
The phylogeny and substitution rates of the mammalian X chromosome- located
and autosomal phosphoglycerate kinase and pyruvate dehydrogenase genes were
investigated. Compatibility analysis was used to show reticulate evolution
in these genes. Analysis of the marsupial, mouse, and human
phosphoglycerate kinase genes suggests that at least two recombination
events have taken place, one occurring about the time of the
placental-marsupial split involving exons 1-5 and the other before the
primate-rodent split involving exons 9-10. Similar analysis of the pyruvate
dehydrogenase genes indicates a recombination event involving exons 2-3 at
a time before the primate-rodent split and a gene conversion between exons
3-4 in the human somatic and testis- specific pyruvate dehydrogenase genes
after the primate-rodent split. This demonstrates that genetic exchange can
occur between paralogous genes at widely separated chromosomal locations.
Estimation of nucleotide substitution rates in these genes confirmed a
higher substitution rate in the pyruvate dehydrogenase genes. In the
phosphoglycerate kinase genes, there is no difference between the
substitution rates in mice and humans and between the X chromosome- and
autosome-located genes. A greater substitution rate was noted in the mouse
autosomal pyruvate dehydrogenase gene when compared with the other mouse
and human genes. This may be a result of either directional natural
selection or a relaxation of functional constraint at this specific gene.
相似文献
The biochemical conversion of lignocellulosic biomass into renewable fuels and chemicals provides new challenges for industrial scale processes. One such process, which has received little attention, but is of great importance for efficient product recovery, is solid–liquid separations, which may occur both after pretreatment and after the enzymatic hydrolysis steps. Due to the changing nature of the solid biomass during processing, the solid–liquid separation properties of the biomass can also change. The objective of this study was to show the effect of enzymatic hydrolysis of cellulose upon the water retention properties of pretreated biomass over the course of the hydrolysis reaction.
Results
Water retention value measurements, coupled with 1H NMR T2 relaxometry data, showed an increase in water retention and constraint of water by the biomass with increasing levels of cellulose hydrolysis. This correlated with an increase in the fines fraction and a decrease in particle size, suggesting that structural decomposition rather than changes in chemical composition was the most dominant characteristic.
Conclusions
With increased water retained by the insoluble fraction as cellulose hydrolysis proceeds, it may prove more difficult to efficiently separate hydrolysis residues from the liquid fraction with improved hydrolysis.
Gene splicing by fusion PCR is a versatile and widely used methodology, especially in synthetic biology. We here describe a rapid method for splicing two fragments by one-round fusion PCR with a dual-asymmetric primers and two-step annealing (ODT) method. During the process, the asymmetric intermediate fragments were generated in the early stage. Thereafter, they were hybridized in the subsequent cycles to serve as template for the target full-length product. The process parameters such as primer ratio, elongation temperature and cycle numbers were optimized. In addition, the fusion products produced with this method were successfully applied in seamless genome editing. The fusion of two fragments by this method takes less than 0.5 day. The method is expected to facilitate various kinds of complex genetic engineering projects with enhanced efficiency. 相似文献
Techniques involving solid supports have played crucial roles in the development of genomics, proteomics, and in molecular biology in general. Similarly, methods for immobilization or attachment to surfaces and resins have become ubiquitous in sequencing, synthesis, analysis, and screening of oligonucleotides, peptides, and proteins. However, solid-phase tools have been employed to a much lesser extent in glycobiology and glycomics. This review provides a comprehensive overview of solid-phase chemical tools for glycobiology including methodologies and applications. We provide a broad perspective of different approaches, including some well-established ones, such as immobilization in microtiter plates and to cross-linked polymers. Emerging areas such as glycan microarrays and glycan sequencing, quantum dots, and gold nanoparticles for nanobioscience applications are also discussed. The applications reviewed here include enzymology, immunology, elucidation of biosynthesis, and systems biology, as well as first steps toward solid-supported sequencing. From these methods and applications emerge a general vision for the use of solid-phase chemical tools in glycobiology. 相似文献
Australia’s gene technology regulatory scheme (GT Scheme) regulates activities with genetically modified organisms (GMOs, organisms modified by gene technology), including environmental releases. The scope of regulation, i.e. what organisms are and are not regulated, is set by the Gene Technology Act 2000 (GT Act) and GT Regulations 2001 (GT Regulations). The GT Act gives broad, overarching definitions of ‘gene technology’ and ‘GMO’ but also provides for exclusions and inclusions in the GT Regulations. Whether organisms developed with genome editing techniques are, or should be, regulated under countries’ national GMO laws is the subject of debate globally. These issues are also under active consideration in Australia. A technical review of the GT Regulations was initiated in 2016 to clarify the regulatory status of genome editing. Proposed draft amendments are structured around whether the process involves introduction of a nucleic acid template. If agreed, amendments would exclude from regulation organisms produced using site directed nuclease (SDN) 1 techniques while organisms produced using oligonucleotide mutagenesis, SDN-2 or SDN-3 would continue to be regulated as GMOs. The review of the GT Regulations is still ongoing and no legislative changes have been made to the GT Regulations. A broader policy review of the GT Scheme was undertaken in 2017–2018 and as a result further work will be undertaken on the scope and definitions of the GT Act in light of ongoing developments.
Despite its clinical importance, a dearth of information exists on the cellular and molecular mechanisms that underpin brain
stem death. A suitable neural substrate for mechanistic delineation on brain stem death resides in the rostral ventrolateral
medulla (RVLM) because it is the origin of a life-and-death signal that sequentially increases (pro-life) and decreases (pro-death)
to reflect the advancing central cardiovascular regulatory dysfunction during the progression towards brain stem death in
critically ill patients. The present study evaluated the hypothesis that heme oxygnase-1 (HO-1) may play a pro-life role as
an interposing signal between hypoxia-inducible factor-1 (HIF-1) and nitric oxide synthase I (NOS I)/protein kinase G (PKG)
cascade in RVLM, which sustains central cardiovascular regulatory functions during brain stem death. 相似文献