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101.
Nielsen J; Peixoto AA; Piccin A; Costa R; Kyriacou CP; Chalmers D 《Molecular biology and evolution》1994,11(6):839-853
The region of the clock gene period (per) that encodes a repetitive tract
of threonine-glycine (Thr-Gly) pairs has been compared between Dipteran
species both within and outside the Drosophilidae. All the non-
Drosophilidae sequences in this region are short and present a remarkably
stable picture compared to the Drosophilidae, in which the region is much
larger and extremely variable, both in size and composition. The
accelerated evolution in the repetitive region of the Drosophilidae appears
to be mainly due to an expansion of two ancestral repeats, one encoding a
Thr-Gly dipeptide and the other a pentapeptide rich in serine, glycine, and
asparagine or threonine. In some drosophilids the expansion involves a
duplication of the pentapeptide sequence, but in Drosophila pseudoobscura
both the dipeptide and the pentapeptide repeats are present in larger
numbers. In the nondrosophilids, however, the pentapeptide sequence is
represented by one copy and the dipeptide by two copies. These observations
fulfill some of the predictions of recent theoretical models that have
simulated the evolution of repetitive sequences.
相似文献
102.
Genetic engineering of cytokinin metabolism: Prospective way to improve agricultural traits of crop plants 总被引:1,自引:0,他引:1
David Zalabák Hana Pospíšilová Mária Šmehilová Katarína Mrízová Ivo Frébort Petr Galuszka 《Biotechnology advances》2013
Cytokinins (CKs) are ubiquitous phytohormones that participate in development, morphogenesis and many physiological processes throughout plant kingdom. In higher plants, mutants and transgenic cells and tissues with altered activity of CK metabolic enzymes or perception machinery, have highlighted their crucial involvement in different agriculturally important traits, such as productivity, increased tolerance to various stresses and overall plant morphology. Furthermore, recent precise metabolomic analyses have elucidated the specific occurrence and distinct functions of different CK types in various plant species. Thus, smooth manipulation of active CK levels in a spatial and temporal way could be a very potent tool for plant biotechnology in the future. This review summarises recent advances in cytokinin research ranging from transgenic alteration of CK biosynthetic, degradation and glucosylation activities and CK perception to detailed elucidation of molecular processes, in which CKs work as a trigger in model plants. The first attempts to improve the quality of crop plants, focused on cereals are discussed, together with proposed mechanism of action of the responses involved. 相似文献
103.
Despite new information concerning functional morphology of spleen, there are still some inaccuracies mostly regarding the
spleen blood circulation. Billroth’s (splenic) cords are formed from three-dimensional network of fibroblastic reticular cells
located among branched sinuses. Results from our study using scanning electron microscopy confirm an intimate contact between
adjacent reticular cells and erythrocytes. Arterial terminals can be observed in the Billroth’s cords. The wall of sinuses
reminds a sieve and it is lined with a special type of endothelium. In electron microscope, endothelial cells look like rods
oriented parallel to the longitudinal axis of sinuses. Based on our observations fibroblastic reticular cells change to fixed
phagocytes under no circumstances, hence they do not participate in phagocytosis. They may have a recognition function for
cells circulating around them. According to our opinion, the open and the closed blood circulation are present in the human
spleen simultaneously. Blood flowing in the closed circulation can help “absorption” of extra-vascular liquid and the blood
elements into the vascular lumen. Due to sporadic occurrence of smooth muscle cells in the capsule and trabeculae, we assume
that human spleen is not a blood reservoir, unlike the spleen in some other animals. 相似文献
104.
105.
Barthélemy X Bouvier G Radunz A Docquier S Schmid GH Franck F 《Photosynthesis research》2000,64(1):63-76
The localization of protochorophyllide (Pchlide) and of NADPH-protochlorophyllide oxidoreductase (POR, EC 1.6.99.1) within
(etio)chloroplasts has been investigated at selected stages of greening of barley seedlings. Pchlide pigment and POR protein
contents were evaluated in different plastid membrane fractions by fluorescence spectroscopy and immunoblot analysis using
a monospecific polyclonal antibody raised against the purified enzyme. Fluorescence analysis showed the presence of Pchlide
in both the envelope and thylakoid membranes. During greening, the Pchlide content, expressed on a total protein basis, decreased
in thylakoid membranes, whereas it increased in the envelope membranes. POR proteins were detected mainly in thylakoid membranes
at early greening stages. In contrast, the weak amount of POR proteins was associated more specifically with envelope membranes
of mature chloroplasts. Whatever the greening stage, thylakoid-bound Pchlide and POR proteins were more abundant in the thylakoid
regions which remained unsolubilized after mild Triton treatment used as standard procedure to prepare PS II particles. This
suggests the preferential association of Pchlide and POR to the appressed regions of thylakoids.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
106.
This study describes the course of enzymatic hydrolysis of the native corn starches Maritena 100 and Maritena 300. Hydrolyses were carried out with glucoamylase Glm produced by Saccharomycopsis fibuligera IFO 0111, which degrades also native starch, with the purpose to substitute a two-step hydrolysis (amylase followed by glucoamylase) by a one-step process (glucoamylase only). Hydrolysis generally became more effective by adding the pullulanase Promozyme D, which cleaves alpha-1,6-glycosidic bonds more effectively than glucoamylase Glm does. The time course (kinetics) of hydrolysis was followed by determination of the glucose concentration and calculation of dextrose equivalents. 相似文献
107.
Added free fatty acids inhibit oxidation of glycerol 3-phosphate, succinate and NADH in brown-adipose tissue mitochondria from 10-day-old rats. The most pronounced is the inhibitory effect of glycerol 3-phosphate cytochrome c reductase (GP-cyto. c reductase). Contrary to other reductases, GP-cyto. c reductase activity of freshly isolated mitochondria is already inhibited by the fraction of endogenous free fatty acids. Both added and endogenous free fatty acids inhibition of GP-cyto. c reductase is fully reversible by the removal of free fatty acids by bovine serum albumine treatment. The inhibition of GP-cyto. c reductase is of strictly non-competitive type. The most inhibitory are unsaturated long-chain free fatty acids-oleic and linoleic acid. Results are discussed with regards to the regulatory importance of free fatty acids in brown-adiposetissue during intensive non-shivering thermogenesis. 相似文献
108.
The aim of the study was to predict both adaptive psychological functioning (well-being) and adaptive social functioning (career stability) in middle adulthood based on behaviors observed in toddlerhood and personality traits measured in adolescence. 83 people participated in an ongoing longitudinal study started in 1961 (58% women). Based on children’s behavior in toddlerhood, three temperamental dimensions were identified – positive affectivity, negative affectivity and disinhibition. In adolescence, extraversion and neuroticism were measured at the age of 16 years. Various aspects of well-being were used as indicators of adaptive psychological functioning in adulthood: life satisfaction, self-esteem and self-efficacy. Career stability was used as an indicator of adaptive social functioning. Job careers of respondents were characterized as stable, unstable or changeable. Extraversion measured at the age of 16 proved to be the best predictor of well-being indicators; in case of self-efficacy it was also childhood disinhibition. Extraversion in adolescence, childhood disinhibition and negative affectivity predicted career stability. Findings are discussed in the context of a theoretical framework of higher order factors of the Big Five personality constructs, stability and plasticity. 相似文献
109.
110.
Tomá? Venit Rastislav Dzijak Al?běta Kalendová Michal Kahle Jana Roho?ková Volker Schmidt Thomas Rülicke Birgit Rathkolb Wolfgang Hans Alexander Bohla Oliver Eickelberg Tobias Stoeger Eckhard Wolf Ali ?nder Yildirim Valérie Gailus-Durner Helmut Fuchs Martin Hrabě de Angelis Pavel Hozák 《PloS one》2013,8(4)