The role of arbuscular mycorrhiza in legume symbiotic performance

Product Description
This digital document is a journal article from Soil Biology and Biochemistry, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

Description:
Legumes may respond to non-rhizobial inoculants such as arbuscular mycorrhizal (AM) fungi either through an effect on plant growth or, in addition, through an effect on the function of the legume-Rhizobium symbiosis. We have examined the literature where the application of ^1^5N isotope dilution methodology permits the effect of indigenous AM and AM inoculants to be quantitatively separated into plant-growth-mediated and biological N”2 fixation (BNF)-mediated components. These studies clearly demonstrate the beneficial effects that both indigenous and inoculated AM have on legume growth, N uptake and the proportional dependence of the legume on atmospheric N”2. While the published data allow an assessment of various biological, edaphic and environmental factors that affect the response of various legumes to AM inoculation, they also highlight the paucity of quantitative field data and the lack of understanding of the interaction of legume genotype with AM species with respect to legume symbiotic performance.

Order from Amazon –> The role of arbuscular mycorrhiza in legume symbiotic performance

Alkalization of larval mosquito midgut and the role of carbonic anhydrase in different species of mosquitoes

Product Description
This digital document is a journal article from Comparative Biochemistry and Physiology, Part C, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

Description:
We have previously demonstrated the involvement of carbonic anhydrase (CA) in the alkalization mechanism of the Aedes aegypti larval midgut. In this study, we used Hansson’s histochemistry to examine the distribution of the enzyme in the midgut of six different species of mosquito larvae (Aedes aegypti, Aedes albopictus, Culex quinquefasciatus, Culex nigripalpus, Ochlerotatus taeniorhynchus, Anopheles quadrimaculatus). Additionally, we quantitated CA content in the gastric caeca, anterior and posterior midgut of fourth instar larvae from these species using the ^1^8O isotope exchange method coupled to mass spectrometry. We also tested the effect of CA inhibitors such as methazolamide and acetazolamide in the alkalization of the midgut for these species. Our results indicate that CA is present in the larval midgut of the species studied and that it appears to be associated with the posterior midgut and gastric caeca in some species and with the anterior midgut in others. CA inhibitors appear to have a profound effect on the alkalization mechanism of the midgut with lethal consequences for most of the species tested.

Order from Amazon –> Alkalization of larval mosquito midgut and the role of carbonic anhydrase in different species of mosquitoes

Cadmium bioaccumulation and detoxification in the gill and digestive gland of the Antarctic bivalve Laternula elliptica

Product Description
This digital document is a journal article from Comparative Biochemistry and Physiology, Part C, published by Elsevier in 2007. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

Description:
Exposure to a sublethal concentration of cadmium (Cd; 50 @mg L^-^1) resulted in significantly increased Cd concentrations in the gill and digestive gland of the Antarctic bivalve Laternula elliptica. Continuous accumulation of Cd in the two organs during the 14-day exposure period was associated with sequestration of Cd to both the soluble cytosolic and insoluble particulate cell fractions. However, the contribution of each cell fraction to Cd sequestration differed between the two organs; in the gill, a larger portion of Cd was associated with the insoluble fraction, while in the digestive gland, both the soluble and insoluble fractions sequestered similar amounts of Cd. Metal-binding components in the insoluble cell fraction were not identified in this study. On the other hand, a metallothionein-like protein (MTLP) was the major Cd-detoxifying component in the soluble cell fraction of the gill and digestive gland. The amount of MTLP increased linearly with exposure time and the amount of Cd accumulated in the tissue, which suggests a potential utility of MTLP as a biomarker for exposure to Cd and possibly other metals.

Order from Amazon –> Cadmium bioaccumulation and detoxification in the gill and digestive gland of the Antarctic bivalve Laternula elliptica

Exploring the mechanisms behind elevated microbial activity after wood ash application

Product Description
This digital document is a journal article from Soil Biology and Biochemistry, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

Description:
Wood ash fertilization increases the pH and concentration of dissolved organic carbon (DOC) in the soil solution and enhances the activity of soil microorganisms. However, it is unknown whether DOC or pH is primarily responsible for the increase in microbial activity. We designed an experiment to separate the effects of DOC and/or pH on soil microbial activity using suspensions of humus extracts and bacteria that had not previously been exposed to wood ash fertilization. After a 3-week incubation, DOC extracts were obtained from control (DOC”C) and ash (DOC”A) treatments with carbon concentrations of 9.1 and 32.5mg Cl^-^1, respectively. These extracts were supplied to bacterial suspensions at concentrations of 0 and 5mg Cl^-^1. We controlled for pH by matching adjustments, i.e. the original pH of the DOC”C extract was 4.5 and its adjusted pH was 6.9, whereas the DOC”A extract was pH 6.9 originally and pH 4.5 adjusted. The relative bacterial growth rate (RBGR), as measured by ^3H-thymidine incorporation, increased in suspensions of 5mg Cl^-^1 DOC as compared to control suspensions of 0mg Cl^-^1. At pH 6.9, RBGR was higher for both DOC extracts than at pH 4.5. These results suggest that both DOC and pH influence microbial activity. As the growth rate at pH 6.9 with DOC”A was higher than with DOC”C, the quality of the DOC extract must also play a role since the carbon concentration was controlled for. The decrease in relative abundance of hydrophobic and hydrophilic acids in DOC”A compared to DOC”C indicates a quality shift. As measured by DGGE banding patterns, the bacterial community structure changed over the course of the 24-h experiment in the following three trials, all of which received 5mg Cl^-^1: DOC”C at pH 6.9 and DOC”A at pH 4.5 and 6.9. These results demonstrate that both the DOC origin (control vs. ash) and the pH influence a subset of the bacterial community.

Order from Amazon –> Exploring the mechanisms behind elevated microbial activity after wood ash application

Gross nitrogen mineralization rates still high 14 years after

Product Description
This digital document is a journal article from Soil Biology and Biochemistry, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

Description:
Significant areas of temperate forests in Central Europe, NE America and E Asia receive high amounts of N deposition. According to the few studies available, suspension of the N load leads to reductions in both inorganic soil N and leaching of N within a few years. We report that, surprisingly, N is still mineralized at high rates 14yr after suspension of a previous N-load of >100kg N/hayr for 20yr. In this treatment, gross N mineralization rates exceeded those in control plots by a factor 3, but equaled those in still on-going (34yr of) treatments with 30 and 60kg N/hayr, in which levels of extractable NH”4^+ were up to 10 times higher.

Order from Amazon –> Gross nitrogen mineralization rates still high 14 years after