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101.
102.
Cholinesterases of the gall bladder 总被引:1,自引:0,他引:1
Kimmo Kyösola 《Histochemistry and cell biology》1977,50(4):337-346
Summary Cholinesterase histochemistry of the human gall bladder was studied using two specific methods.Distribution of acetylcholinesterase: In the mucosa, nerve fascicles consisting of densely packed parallel single nerve fibres, small ganglia and spot-and glomerule-like concentrations of acetylcholinesterase activity were observed. In the muscle layer, a wide-meshed network of delicate nerves, with occasional areas of very dense innervation, and small ganglia were seen. In the serosa, glomerule-like structures surrounded by dense baskets of delicate nerves were observed. — The general scheme of distribution of non-specific cholinesterases was similar to that of acetylcholinesterase.It seems that the cholinergic innervation of the gall bladder is related to both secretion and absorption and contractility. Some cholinergic nerves are probably sensory, especially because acetylcholinesterase-positive structures, possibly pressure of stretch receptors, supplied with nerves were observed in the mucosa and the serosa. The cholinergic innervation of the gall bladder muscle was scarce except occasional areas of very dense innervation. It may thus be concluded that the intermuscle spread of excitation plays an important role, the majority of the smooth muscle cells receiving their nervous influence via electrotonic coupling. 相似文献
103.
Effects of ethylene and auxin on polyamine levels in suspension-cultured tobacco cells 总被引:1,自引:0,他引:1
The effects of ethylene and auxin on polyamine levels were studied in suspension-cultured cells of tobacco ( Nicotiana tabacum . L). Treatment of 4-day-cultured cells with ethylene increased the levels of spermidine and spermine. The activities of arginine decarboxylase (ADC; EC 4.1.1.19), ornithine decarboxylase (ODC: EC 4.1.1.17), and S -adenosylmethionine decarboxylase (SAMDC: EC 4.1.1.50) rapidly increased between 3 and 12 h. An auxin, indole-3-acetic acid (IAA), increased polyamine levels and activities of ADC, ODC and SAMDC. The spermine level continued to increase significantly during a 24-h incubation with IAA. The increases in polyamine accumulation induced by ethylene were partially offset by an inhibitor of ethylene action, 2,5-norbornadiene. It is suggested that the auxin-induced polyamine accumulation occurred directly, without metabolic competition between ethylene and polyamine biosynthesis, and indirectly, through auxin-induced ethylene formation. 相似文献
104.
A left-handed RNA double helix bound by the Z alpha domain of the RNA-editing enzyme ADAR1 总被引:2,自引:0,他引:2
Placido D Brown BA Lowenhaupt K Rich A Athanasiadis A 《Structure (London, England : 1993)》2007,15(4):395-404
The A form RNA double helix can be transformed to a left-handed helix, called Z-RNA. Currently, little is known about the detailed structural features of Z-RNA or its involvement in cellular processes. The discovery that certain interferon-response proteins have domains that can stabilize Z-RNA as well as Z-DNA opens the way for the study of Z-RNA. Here, we present the 2.25 A crystal structure of the Zalpha domain of the RNA-editing enzyme ADAR1 (double-stranded RNA adenosine deaminase) complexed to a dUr(CG)(3) duplex RNA. The Z-RNA helix is associated with a unique solvent pattern that distinguishes it from the otherwise similar conformation of Z-DNA. Based on the structure, we propose a model suggesting how differences in solvation lead to two types of Z-RNA structures. The interaction of Zalpha with Z-RNA demonstrates how the interferon-induced isoform of ADAR1 could be targeted toward selected dsRNAs containing purine-pyrimidine repeats, possibly of viral origin. 相似文献
105.
Antti Kause Vladimir Ossipov Erkki Haukioja Kyösti Lempa Sinikka Hanhimäki Svetlana Ossipova 《Oecologia》1999,120(1):102-112
Due to rapidly changing physical and biochemical characteristics of growing leaves, correlations between traits of foliage
biochemistry and the performance indices of flush feeding herbivores may vary considerably following relatively minor changes
in experimental conditions. We examined the effects of the seasonal and inter-tree variation of a comprehensive array of biochemical
compounds on the success of an early season geometrid, Epirrita autumnata, feeding on maturing foliage of mountain birch, Betula pubescens ssp. czerepanovii. We monitored the concentrations of individual phenolics, sugars, total nitrogen, nitrogen of proteins, and nitrogen of soluble
compounds, water and acetone-insoluble residue. Simultaneously we recorded larval consumption, physiological performance,
growth, and pupal mass of E. autumnata. We found significant phenological changes in almost all leaf traits measured. In bioassays with half-grown leaves, leaf
gallotannin concentrations showed a nonlinear effect: in trees with high foliar gallotannin concentrations (over 10 mg g−1), physiological performance was strongly reduced by high gallotannin concentrations. In trees with lower gallotannin concentrations,
on the other hand, larval growth was reduced by soluble proanthocyanidins, not gallotannins. Differences between high and
low gallotannin trees largely depended on phenology, i.e., on the age of leaves. However, not all the differences in leaf
traits between late (with high gallotannin concentrations at the time of the bioassay) and early flushing trees disappeared
with leaf maturation, indicating that there is also phenology-independent variance in the tree population. In the full-grown
leaves of all the study trees, low concentrations of water and of nitrogen of proteins (but not nitrogen of soluble compounds)
were the main factors reducing pupal masses of E. autumnata, while neither gallotannin nor proanthocyanidins now played a significant role. The observed change in the factors underlying
leaf quality (from gallotannins and proanthocyanidins to nitrogen and water) relate to the activity of the shikimate pathway
and the formation of cell walls: gallotannins and proanthocyanidins are both produced in the pathway, and these tannins are
assumed to contribute – via binding into cell walls – to tough and durable cell walls. Interestingly, low quality of leaves
did not automatically translate into low foliar consumption (i.e., benefits to the tree). On the trees with young, high gallotannin
leaves, larvae actually increased consumption on low quality foliage. In the group of trees with slightly more developed,
low gallotannin leaves, the quality of leaves did not clearly modify amounts consumed. In full-grown leaves, low leaf quality
strongly reduced leaf consumption. These results emphasize the strong influence of tree phenology on the relationships between
biochemical compounds and the herbivore.
Received: 30 November 1998 / Accepted: 1 March 1999 相似文献
106.
Interspecific genetic linkage map, segregation distortion and genetic conversion in coffee (Coffea sp.) 总被引:1,自引:0,他引:1
C. L. Ky P. Barre M. Lorieux P. Trouslot S. Akaffou J. Louarn A. Charrier S. Hamon M. Noirot 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2000,101(4):669-676
An interspecific partial genetic linkage map of Coffea sp. based on 62 backcross hybrids is presented. F1 hybrids were generated by a cross between the wild C. pseudozanguebariae and the anciently cultivated C. liberica var. dewevrei (DEW); progeny were then derived from a backcross between F1 hybrid and DEW. The map construction consisted of a two-step strategy using 5.5 and 3.1 LOD scores revealed by simulation
file. The map consisted of 181 loci: 167 amplified fragment length polymorphism (AFLP) and 13 random fragment length polymorphism
(RFLP) loci. The markers were assembled into 14 linkage groups, each with 4–31 markers covering 1,144 cM. Segregation distortion
was observed for 30% of all loci, in particular 3:1 and 1:3 ratios equally favouring each of the two parents. The existence
of such ratios suggests genetic conversion events. This map also represents an initial step towards the detection of quantitative
trait loci.
Received: 4 Janaury 2000 / Accepted: 17 January 2000 相似文献
107.
108.
Ky B. Koitzsch Colby B. Anton Lisa O. Koitzsch Tessa L. Tjepkes Abby C. Schumann Jared L. Strasburg 《The Journal of wildlife management》2022,86(4):e22200
Acquiring demographic data for moose (Alces alces) can be difficult because they are solitary in nature, they prefer densely vegetated and mountainous habitats, and they often occur at low density. Such data, however, are essential for long-term population monitoring, evaluating management practices, and effective conservation. Winter aerial surveys are the standard method for estimating moose population parameters, but they can be logistically challenging, expensive, and subject to sightability correction, which necessitates the capture of study animals for initial model development. Herein, we demonstrate a noninvasive alternative approach for estimating population parameters of moose in northern Yellowstone National Park, where aerial surveys were attempted but proved ineffective. We determined individual moose genotype and sex using microsatellite polymerase chain reaction amplification of DNA extracted from fecal pellets, integrated ancillary pellet sample data (i.e., metadata) in genotype analysis to aid in the identification of matching genotypes, and used spatially explicit capture-recapture (SECR) modeling to estimate sex-specific density and abundance. We collected 616 samples over 3 consecutive winters (Dec 2013–Apr 2016) and within 2 sampling occasions each winter. We recorded 514 captures of 142 individual moose (69 males, 73 females). Overall density ranged between 0.062 moose/km2 and 0.076 moose/km2 and averaged 0.034/km2 for females and 0.033/km2 for males. Abundance estimates were 150 moose in 2013 (female = 76, 95% CI = 55–105; male = 74, 95% CI = 54–103), 186 in 2014 (female = 95, 95% CI = 63–142; male = 91, 95% CI = 60–138), and 160 in 2015 (female = 79, 95% CI = 58–108; male = 81, 95% CI = 59–110). Average population sex ratio was 0.99 males/female. We demonstrate that SECR analysis of fecal DNA genotypes, using metadata in genotype analysis to help identify matching moose genotypes, is a promising alternative method for estimating sex-specific density and abundance of a low-density moose population in a mountainous and forested landscape. 相似文献
109.
Tonthat NK Arold ST Pickering BF Van Dyke MW Liang S Lu Y Beuria TK Margolin W Schumacher MA 《The EMBO journal》2011,30(1):154-164
In Escherichia coli, cytokinesis is orchestrated by FtsZ, which forms a Z-ring to drive septation. Spatial and temporal control of Z-ring formation is achieved by the Min and nucleoid occlusion (NO) systems. Unlike the well-studied Min system, less is known about the anti-DNA guillotining NO process. Here, we describe studies addressing the molecular mechanism of SlmA (synthetic lethal with a defective Min system)-mediated NO. SlmA contains a TetR-like DNA-binding fold, and chromatin immunoprecipitation analyses show that SlmA-binding sites are dispersed on the chromosome except the Ter region, which segregates immediately before septation. SlmA binds DNA and FtsZ simultaneously, and the SlmA-FtsZ structure reveals that two FtsZ molecules sandwich a SlmA dimer. In this complex, FtsZ can still bind GTP and form protofilaments, but the separated protofilaments are forced into an anti-parallel arrangement. This suggests that SlmA may alter FtsZ polymer assembly. Indeed, electron microscopy data, showing that SlmA-DNA disrupts the formation of normal FtsZ polymers and induces distinct spiral structures, supports this. Thus, the combined data reveal how SlmA derails Z-ring formation at the correct place and time to effect NO. 相似文献
110.