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641.
Salinity effects on germination,growth, and seed production of the halophyte Cakile maritima 总被引:1,自引:0,他引:1
The growth ofEucalyptus regnans seedlings in forest soil is enhanced when it has been air-dried. In undried forest soil seedlings grow poorly and develop
purple coloration in the foliage, indicating P deficiency. This paper reports the results of pot experiments designed to investigate
the relationship between growth and P acquisition, ectomycorrhizal infection and age of seedlings grown in air-dried and undried
soil. The effect on seedling growth of their inoculation with air-dried or undried soil or with ectomycorrhizal roots from
plants growing in air-dried or undried soil was also investigated. Ectomycorrhizal root tips were detected in 3-week-oldE. regnans seedlings in both air-dried and undried soil, and from then on the frequency of ectomycorrhizal root tips increased rapidly.
In air-dried soil, seedlings were fully ectomycorrhizal at 9 weeks, and the occurrence of maximum ectomycorrhizal infection
coincided with enhanced P acquisition and the initiation of rapid seedling growth. In undried forest soil, seedling growth
remained poor, even though the seedlings had well-developed ectomycorrhizae and the incidence of ectomycorrhizal root tips
was the same as in air-dried soil. The dominant ectomycorrhizae in airdried soil were associated with an ascomycete fungus,
whereas in undried, undisturbed soil they were commonly associated with basidiomycete fungi. Inoculation of sterile soil/sand
mix with washed ectomycorrhizal roots from air-dried soil increased the P acquisition and growth of the seedlings significantly
compared with controls, whereas ectomycorrhizal inocula from undried soil had no effect on seedling growth, although both
inocula resulted in a similar incidence of ectomycorrhizal root tips. Similarly, addition of a small amount of air-dried soil
into sterile soil/sand mix resulted in a significantly greater increase in the P content and dry weight of the seedlings,
compared with the control, than addition of undried soil. In both treatments, the incidence of ectomycorrhial root tips was
similar. As (i) the differentiation in seedling growth between air-dried and undried soil occurred after seedlings became
ectomycorrhizal, (ii) the dominant ectomycorrhizae in air-dried soil were different from those in undried soil, and (iii)
inocula from air-dried soil, but not from undried soil, stimulated seedling growth in sterile soil/sand mix, it is concluded
that development of particular ectomycorrhizae may be involved in seedling growth stimulation and enhanced P acquisition associated
with air drying of forest soil. 相似文献
642.
Neutrophils clear bacteria associated with parasitic nematodes augmenting the development of an effective Th2-type response 总被引:2,自引:0,他引:2
Pesce JT Liu Z Hamed H Alem F Whitmire J Lin H Liu Q Urban JF Gause WC 《Journal of immunology (Baltimore, Md. : 1950)》2008,180(1):464-474
Infection with the parasitic nematode Nippostrongylus brasiliensis induces a potent Th2 response; however, little is known about early stages of the innate response that may contribute to protective immunity. To examine early events in this response, chemokine expression in the draining lymph node was examined after N. brasiliensis inoculation. Pronounced increases of several chemokines, including CCL2, were observed. Compared with wild-type mice, elevations in a Gr-1bright population in the draining lymph node was significantly decreased in CCL2-/- mice after N. brasiliensis inoculation. Further flow cytometric and immunofluorescent analysis showed that in wild-type mice, Gr-1+ cells transiently entered and exited the draining lymph node shortly after N. brasiliensis inoculation. The Gr-1bright population was comprised of neutrophils expressing TGF-beta and TNF-alpha. Following Gr-1+ cell depletion, N. brasiliensis infection resulted in transient, but significantly increased levels of IFN-gamma, increased serum IgG2a, reduced Th2 cytokines and serum IgE, greatly increased mortality, and delayed worm expulsion. Furthermore, bacteria were readily detected in vital organs. Infection of Gr-1+ cell-depleted mice with N. brasiliensis larvae that were pretreated with antibiotics prevented bacterial dissemination, Th1 inflammatory responses, and decreases in host survival. This study indicates that parasitic nematodes can be an important vector of potentially harmful bacteria, which is typically controlled by CCL2-dependent neutrophils that ensure the optimal development of Th2 immune responses and parasite resistance. 相似文献
643.
In the work presented, the changes in codon and amino acid contents have been studied as a function of environmental conditions by comparing pairs of homologs in a group of extremophilic/non-extremophilic genomes. Our results obtained based on such analysis highlights a number of notable observations: (i) the overall preference of amino acid usages in the proteins of a given organism is significantly affected by major environmental factors. The changes in amino acid preferences (amino acid usage profiles) in an extremophile compared to its non-extremophile relative recurs in the organisms of similar extreme habitats. (ii) On the other hand, changes in codon usage preferences in these extremophilic/non-extremophilic pairs, lack such persistency not only in different genome-pairs but also in the individual genes of a specific pair. (iii) We have noted a correlation between cellular function and codon usage profiles of the genes in the studied pairs. (iv) Based on this correlation, we could obtain a decent prediction of cellular functions solely based on codon usage profile data. (v) Comparisons made between two sets of randomly generated genomes suggest that different patterns of codon usage changes in genes of different functional categories result in a partial resistance towards the changes in the concentration of a given amino acid. This buffering capacity might explain the observed differences in codon usage trends in genes of different functions. In the end, we suggest codon usage and amino acid profiles as powerful tools that can be utilized to improve function predictions and genome-environment mappings. 相似文献
644.
Nazzari H Angoli D Chow SS Whitaker G Leclair L McDonald E Macri V Zahynacz K Walker V Accili EA 《American journal of physiology. Cell physiology》2008,295(3):C642-C652
Previous studies have suggested that a portion of the cyclic nucleotide-binding domain (CNBD) of the hyperpolarization-activated cyclic nucleotide-gated channel 2 (HCN2) "pacemaker" channel, composed of the A- and B-helices and the interceding beta-barrel, confers two functions: inhibition of channel opening in response to hyperpolarization and promotion of cell surface expression. The sequence determinants required for each of these functions are unknown. In addition, the mechanism underlying plasma membrane targeting by this subdomain has been limitedly explored. Here we identify a four-amino acid motif (EEYP) in the B-helix that strongly promotes channel export from the endoplasmic reticulum (ER) and cell surface expression but does not contribute to the inhibition of channel opening. This motif augments a step in the trafficking pathway and/or the efficiency of correct folding and assembly. 相似文献
645.
In order to assess symbiotic activity (the nodules integrity and the iron use efficiency) in common bean (Phaseolus vulgaris L.) under low iron availability, the growth of plants and nodules, the concentration of leghaemoglobin and malondialdehyde,
and activity of nitrogenase, catalase, peroxidase and superoxide dismutase were analysed in two (contrasting) common bean
varieties subjected to iron deficiency. Results show that nitrogen fixation and leghaemoglobin accumulation decreased at limiting
iron availability while malondialdehyde concentration increased under these conditions. The tolerant variety to iron deficiency,
ARA14, was clearly less affected than the sensitive one, Coco blanc. A significant stimulation of peroxidase (POD) activity
was observed in ARA14 under iron deficiency. At the same conditions, SOD and CAT activities in ARA14 plants were maintained
at high level. It was also found that the iron use efficiency for leghaemoglobin accumulation, SOD, CAT and POD activities
were critical for the protection of symbiotic system against oxidative burst and for the maintaining of an optimal functioning
of N2 fixing system. 相似文献
646.
Sayed Mehdi Hosseini Bahman Bahramnejad Hamed Douleti Baneh Aryo Emamifar Paul H. Goodwin 《World journal of microbiology & biotechnology》2017,33(4):67
Resveratrol is a polyphenolic compound produced in very low levels in grapes. To achieve high yield of resveratrol in wild grape, three Agrobacterium rhizogenes strains, Ar318, ArA4 and LBA9402, were used to induce hairy roots following infection of internodes, nodes or petioles of in vitro grown Vitis vinifera subsp. sylvesteris accessions W2 and W16, and cultivar Rasha. The effects of inoculation time, age of explants, bacterial concentration and co-cultivation times were examined on the efficiency of the production of hairy roots. Strains Ar318, ArA4 and LBA9402 all induced hairy roots in the tested genotypes, but the efficiency of ArA4 strain was higher than the other strains. The highest hairy root production was with using internodes as explants. The transformation of hairy roots lines was confirmed by PCR detection of rolB gene. Half Murashige and Skoog (MS) medium was better for biomass production compared with MS medium. HPLC analysis of resveratrol production in the hairy root cultures showed that all the genotypes produced higher amounts of resveratrol than control roots. The highest amount of resveratrol was produced from W16 internode cultures, which was 31-fold higher than that of control root. Furthermore, TLC analysis showed that treatments of hairy roots with sodium acetate and jasmonate elevated resveratrol levels both in hairy root tissue and excreted into the half MS medium. These results demonstrate that endogenous and exogenous factors can affect resveratrol production in hairy root culture of grape, and this strategy could be used to increase low resveratrol production in grapes. 相似文献
647.
Hamed A. Salama Mahmoud Ghorab Azza A. Mahmoud Mayssa Abdel Hady 《AAPS PharmSciTech》2017,18(7):2517-2528
Nanoparticles fabricated from the biodegradable and biocompatible polymer, polylactic-co-glycolic acid (PLGA), could be a promising system for targeting ocular drug delivery. The objective of this work was to investigate the possibility of encapsulating brinzolamide in PLGA nanoparticles in order to be applied as a subconjunctival injection that could represent a starting point for developing new therapeutic strategies against increase in ocular pressure. The brinzolamide-loaded PLGA nanoparticles were fabricated using emulsion-diffusion-evaporation method with varying concentrations of Tween 80 or poloxamer 188 (Plx) in aqueous and organic phases. The nanoparticles were characterized in terms of particle size and size distribution, entrapment efficiency and in-vitro drug release pattern as well as DSC and X-ray analysis. Nanoparticles prepared using Tween 80 in the aqueous phase showed higher encapsulation efficiency and smaller particle size-values compared to those prepared using Plx. Furthermore, the addition of Plx 188 or Brij 97 to the organic phase in the formulation containing Tween 80 in the aqueous phase led to an increase in the particle diameter-values of the obtained nanoparticles. The nanoparticles had the capacity to release the brinzolamide in a biphasic release profile. The nanoparticles were spherical in shape and the drug was entraped in the nanoparticles in an amorphous form. Selected nanoparticles, injected subconjunctivally in normotensive Albino rabbits, were able to reduce the IOP for up to 10 days. Nanoparticles loaded with brinzolamide with lower particle size were able to reduce the IOP for longer period compared to those with higher particle size. Histopathological studies for the anterior cross sections of the rabbits’ eyes revealed that the tested nanoparticles were compatible with the ocular tissue. The overall results support that PLGA nanoparticles, applied as subconjunctival injection, can be considered as a promising carrier for ocular brinzolamide delivery with targeting delivery of the drug to the eye tissues. 相似文献
648.
Ben Hamed K Ben Youssef N Ranieri A Zarrouk M Abdelly C 《Journal of plant physiology》2005,162(5):599-602
In the halophyte Crithmum maritimum, the sulfolipid content increased considerably in the presence of NaCl. There were no significant changes in the total fatty acid composition of sulfolipids during salt treatment, except for linoleic and linolenic acids. In comparison to the control plants, sulfolipids in NaCl-treated plants showed a decrease in the percentage of unsaturated fatty acid (C18:3), and a corresponding increase in the percentage of unsaturated fatty acids (C18:2). As a whole, the data reported in this work suggest that sulfolipds may be one important aspect of strategies involved in salt tolerance of this halophyte. 相似文献
649.
Ebrahimkhani MR Sadeghipour H Dehghani M Kiani S Payabvash S Riazi K Honar H Pasalar P Mirazi N Amanlou M Farsam H Dehpour AR 《Life sciences》2005,76(21):2497-2512
Homocysteine (Hcy), an intermediate in methionine metabolism, has been proposed to be involved in hepatic fibrogenesis. Impaired liver function can alter Hcy metabolism. The aim of the present study was to determine plasma Hcy alterations in acute obstructive cholestasis and the subsequent biliary cirrhosis. Cholestasis was induced by bile duct ligation and sham-operated and unoperated rats were used as controls. The animals were studied on the days 7th, 14th, 21st and 28th after the operation. Plasma Hcy, cysteine, methionine, nitric oxide (NO) and liver S-adenosyl-methionine (SAM), S-adenosyl-homocysteine (SAH), SAM to SAH ratio and glutathione were measured. Chronic L-NAME treatment was also included in the study. Plasma Hcy concentrations were transiently elevated by the day 14th after bile duct ligation (P < 0.01) and subsequently returned to control levels. Similar relative fluctuations in plasma Hcy were observed in BDL rats after intraperitoneal methionine overload. Plasma methionine, cysteine and nitrite and nitrate were significantly increased after bile duct ligation. SAM to SAH ratio was diminished by the 1st week of cholestasis and remained significantly decreased throughout the study. These events were accompanied by a decrease in GSH to GSSG ratio in the liver. Chronic L-NAME treatment improved SAM to SAH ratio and prevented the elevation of plasma Hcy and methionine (P < 0.05) while couldn't influence the other parameters. In conclusion, this study demonstrates alterations in plasma Hcy and liver SAM and SAH contents in precirrhotic stages and in secondary biliary cirrhosis, for the first time. In addition, we observed that plasma Hcy concentrations in BDL rats follow a distinct pattern of alteration from what has been previously reported in other models of cirrhosis. NO overproduction may contribute to plasma Hcy elevation and liver SAM depletion after cholestasis. 相似文献
650.
Nonrandom patterns in codon assignments are supported by many statistical and biochemical studies in the last two decades. The canonical genetic code is known to be highly efficient in minimizing the effects of mistranslational errors and point mutations, an ability, which in term is designated "load minimization". Prior studies have included many attempts at quantitative estimation of the fraction of randomly generated codes, which in terms of load minimization, score higher than the canonical genetic code. In this study, a neural network, which estimates a highly optimized genetic code in a relatively short period of time has been devised. Several fitness functions were used throughout this text. Meanwhile, we have made use of two cost measure matrices, PAM74-100 and mutation matrix. 相似文献