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91.
Summary Immunoreactivity for the neurofilament protein triplet was investigated in neurons of the dorsal root ganglia of the guinea-pig by using a battery of antibodies. In unfixed tissue, nearly all neurons in these ganglia demonstrated some degree of neurofilament protein triplet immunoreactivity. Large neurons generally displayed intense immunoreactivity, whereas most small to medium-sized neurons showed faint to moderate immunoreactivity. Double-labelling immunofluorescence demonstrated that most antibodies to the individual subunits of the neurofilament protein triplet had the same distribution and intensity of labelling in sensory neurons. Increasing durations of tissue fixation in aldehyde solutions selectively diminished neurofilament protein triplet immunoreactivity in small to medium-sized neurons. Double-labelling with neurofilament protein triplet antibodies in combination with antibodies to other neuronal markers, such as neuron-specific enolase, substance P and tyrosine hydroxylase, showed that tissue processing conditions affect the degree of co-localization of immunoreactivity to the neurofilament protein triplet and to these other neuronal markers. These results indicate that, with a judicious manipulation of the duration of tissue fixation, neurofilament protein triplet immunoreactivity can be used in combination with other neuronal markers to distinguish groups of neurons according to their size and chemical coding. 相似文献
92.
Rolf Altenburger Sibylle Abarzua Rainer Callies L. Horst Grimme Adalbert Mayer Dieter Leibfritz 《Archives of microbiology》1991,156(6):471-476
Cultures of the cyanobacterium Microcystis firma show rhythmic uptake and release of ammonia under conditions of carbon limitation. The massive removal of ammonia from the medium during the first light phase has little impact on the intracellular pH: a pH shift of less than 0.2 U towards the alkaline can be measured by in vivo 31P NMR. Furthermore, the energy status of the cells remains regulated. In vivo 15N NMR of M. firma, cultivated either with labelled nitrate or ammonia as the sole nitrogen source, reveals only gradual differences in the pool of free amino acids. Additionally both cultivation types show -aminobutyric acid, acid amides and yet unassigned secondary metabolites as nitrogen storing compounds. Investigating the incorporation of nitrogen under carbon limitation, however, only the amide nitrogen of glutamine is found permanently labelled in situ. While transamination reactions are blocked, nitrate reduction to ammonia can still proceed. Cation exchange processes in the cell wall are considered regarding the ammonia disappearance in the first phase, and the control of ammonia uptake is discussed with respect to the avoidance of intracellular toxification.Abbreviations GABA
-aminobutyric acid
- GOGAT
glutamate synthase
- GS
glutamine synthetase
- MDP
methylene diphosphonate
- MOPSO
3-(N-morpholino)-2-hydroxy-propanesulfonic acid
- NDPS
nucieoside diphosphosugars
- NOE
nuclear Overhauser effect
- NMR
nuclear magnetic resonance
For convenience, the term ammonia is used throughout to denote ammonia or ammonium ion when there is no good evidence as to which chemical species is involved 相似文献
93.
The pinewood nematode, Bursaphelenchus xylophilus, was inoculated into established native jack and red pines (Pinus banksiana and P. resinosa) and exotic Austrian pine (P. nigra) in Minnesota and Wisconsin forests during summer 1981. The nematode isolates did not kill established nonstressed pine trees growing in the forest. However, the same nematode isolates killed pine seedlings under greenhouse conditions. Girdling the main stem of some trees to induce stress resulted in the death of the majority of inoculated and noninoculated branches of Austrian and jack pines, but no branch death was observed on red pine. Greater numbers of nematodes were extracted from branches of inoculated, girdled trees than from nongirdled trees. The mean number of nematodes extracted from branches of inoculated, nongirdled trees was 0.3 - 14 nematodes per gram of wood. 相似文献
94.
Summary A re-examination of earlier NPK fertilization experiments in Douglas fir stands on sandy soils shows the effects of high nitrogen
input by air pollution during the last 10–15 years on plant nutrition at these sites. In 1960, experimental plots showed a
positive growth reaction to nitrogen, phosphorus, and potassium fertilization. All suffered from severe phosphorus deficiency
in 1984, low phosphorus in the needles was invariably accompanied by a high nitrogen content, with all N/P ratios between
20 and 30. The same conclusion emerges from an independent investigation of nutrient status of a selection of Douglas fir
stands. Hence, if stand productivity and a balanced nutrient status of the trees is to be maintained, the increase in atmospheric
input of nitrogen calls for supplementary fertilization. Given the current N/P ratios in the needles, a positive growth response
to phosphorus fertilization is to be expected. 相似文献
95.
Summary Surface soil materials from the 0- to 15 cm depth of 12 sites that were suspected to contain high levels of P, as a result
of years of repeated applications of either inorganic or organic P fertilizers, were cropped with wheat and alfalfa in the
greenhouse for about one year. The total P removed in plant materials provided an estimate of the plant available P in the
soils. The probable dominant phosphate compound controlling the release of P in the soil solution during cropping was determined
using the GEOCHEM program and an activity diagram. The data show that P availability is partly dependent on the stability
of the phosphate compound present, although the relative positions of the points on the activity diagram show no quantitative
relationship with either the total plant P uptake or the phosphate buffering capacity of the soils. The positions of the points,
however, indicate that with time the formation of more stable P compounds during cropping could be attributed to reactions
in the soil as well as to crop removal.
The more soluble compounds could have recrystallized or were transformed into compounds of lower solubility. There is also
the possibility that the more soluble P compounds were exhausted by crop removal leaving behind the less soluble compounds. 相似文献
96.
Chemical limnology of two artificial lakes used for both stormwater management and recreation 总被引:1,自引:1,他引:0
The aims of this study were to document the mainly chemical behaviour of two linked artificial lakes used for both stormwater management and recreation in the new town of Craigavon. Further, the understanding of their behaviour should help in their management and the design of other similar lakes.The lake mean total phosphorus (73 µg P l–1), nitrate (0.50 mg N l–1) and chlorophyll a (25 µg l–1) concentrations, Secchi depth (1.2 m) and the estimated total phosphorus loading (1.98 g m–2 a–1) all classify the main lake as eutrophic. An important source of the phosphorus load on the lakes is the urban area of Craigavon (52% of the total load). The interrelationships between total phosphorus, chlorophyll a and Secchi depth in the main lake are similar to those in natural ones. In addition, the lake follows the total phosphorus load — trophic state relationships (lake total phosphorus and chlorophyll a concentrations and Secchi depth) found to apply elsewhere. These two points indicate that the artificial lakes in Craigavon behave similarly to natural ones. 相似文献
97.
Claude Vallet-Strouve Charles Tellier Serge Poignant Philippe Boucrot 《The Journal of membrane biology》1985,84(1):73-79
Summary The effect of biliary salts and fatty acids on the bilayer structure of rabbit intestinal brush-border membranes was studied using the nonperturbing probe31P NMR. The broad. asymmetric lineshape of the31P NMR spectrum of isolated brush-border vesicles demostrates that their component phospholipids are organized in extended bilayers. These membranes are not significantly perturbed by incubation with physiological concentrations of biliary salts (3, 9, 18mm), demonstrating that the vesicles are highly stable, corresponding to their biological function. However, the emergence of a narrow peak superimposed on the broad lineshape indicates that a small proportion of the membrane phospholipids has reached isotropic motion, which may correspond to external or internal micellar structures. Incubation with mixed micelles of fatty acids and taurochlorate show that long-chain fatty acids enhance the membrane-perturbing effect of taurocholate while short-chain, watersoluble fatty acids do not, suggesting a difference in the absorption mechanisms. 相似文献
98.
Evolution of the lipoprotein gene in the enterobacteriaceae. Cloning and DNA sequence of the lpp gene from Proteus mirabilis 总被引:3,自引:0,他引:3
We cloned the lipoprotein gene from Proteus mirabilis and determined its DNA sequence. Comparison with the lpp genes from Escherichia coli, Serratia marcescens, Erwinia amylovora and Morganella morganii revealed several unique features of the evolution of the lpp gene in the Enterobacteriaceae and enabled us to establish phylogenetic relationships between these bacteria. 相似文献
99.
Nitrobenzylthioinosine binding in brain: an interspecies study 总被引:3,自引:0,他引:3
The binding of the potent adenosine uptake inhibitor [3H]nitrobenzylthioinosine ( [3H]NBI) to cerebral cortical membrane preparations from human, dog, guinea pig, rat, and mouse was investigated. Reversible, specific, saturable, high affinity binding was found in all five species with similar kinetic parameters. (Kd = 0.16-0.44 nM; Bmax = 128-196 fmol/mg prot.). Dilazep, hexobendine, and dipyridamole were all high potency inhibitors of [3H]NBI binding in human, dog, guinea pig and mouse preparations but not in rat. These compounds showed a competitive inhibition of [3H]NBI binding indicating that they are acting at the same site. Discrepancies seen in the rat appear to be a unique, species related anomaly. The dihydropyridine calcium antagonists also inhibited binding with lower potency than the adenosine uptake blockers. This inhibition was most potent in dog and human and suggests a relationship between the calcium channel and the adenosine uptake site. 相似文献
100.
Effect of salinity on mycorrhizal onion and tomato in soil with and without additional phosphate 总被引:22,自引:1,他引:21
Summary Vesicular-arbuscular mycorrhizal fungi (VAM) are known to increase plant growth in saline soils. Previous studies, however, have not distinguished whether this growth response is due to enhanced P uptake or a direct mechanism of increased plant salt tolerance by VAM. In a glasshouse experiment onions (Allium cepa L.) were grown in sterilized, low-P sandy loam soil amended with 0, 0.8, 1.6 mmol P kg–1 soil with and without mycorrhizal inoculum. Pots were irrigated with saline waters having conductivities of 1.0, 2.8, 4.3, and 5.9 dS m–1. Onion colonized withGlomus deserticola (Trappe, Bloss, and Menge) increased growth from 394% to 100% over non-inoculated control plants when soil P was low ( 0.2 mmol kg–1 NaHCO3-extractable P) at soil saturation extract salinities from 1.1 dS m–1 to 8.8 dS m–1. When 0.8 and 1.6 mM P was added no dry weight differences due to VAM were observed, however, K and P concentrations were higher in VAM plants in saline treatments.Glomus fasciculatum (Gerdeman and Trappe) andGlomus mosseae (Nicol. and Gerd.) isolates increased growth of VAM tomato 44% to 193% in non-sterilized, saline soil (10 dS m–1 saturation extract) despite having little effect on growth in less saline conditions when soil P was low. Higher tomato water potentials, along with improved K nutrition by VAM in onion, indicate mechanisms other than increased P nutrition may be important for VAM plants growing under saline stress. These effects appear to be secondary to the effects of VAM on P uptake. 相似文献