Iron deficiency

Iron deficiency and anemia affect a substantial portion of the world’s population, provoking severe health problems to the people suffering these conditions, as well as important economic losses to the regions in which this nutritional deficiency is significant. In this work, the principal causes and consequences produced by this deficiency are discussed, as well as the different strategies that can be applied in order to prevent and solve this nutritional problem.     

Iron deficiency on neuronal function

Because of the intrinsic ability of iron to catalyze the formation of reactive oxygen species, it has been associated with oxidative stress and neurodegenerative diseases. However, iron deficiency (ID) also negatively impacts various functions of the brain, suggesting that iron plays an important physiological role in neuronal processes such as myelination, synaptogenesis, behavior and synaptic plasticity (SP). ID not only produces changes in the hippocampus, striatum, amygdale or prefrontal cortex, it also affects the interaction among these systems. In both humans and rodents, the perturbations of these structures are associated to cognitive deficits. These cognitive alterations have been well correlated with changes in neural plasticity, the possible cellular substrate of memory and learning. Given that SP is strongly affected by early ID and the lasting-neurological consequences remain even after ID has been corrected, it is important to prevent ID as well as to seek effective therapeutic interventions that reduce or reverse the long-term effects of the ID in the nervous system. This review will give an overview of the literature on the effects of iron deficit in neuronal functions such as behavior, neurotransmission and SP. We also discuss our recent data about the possible oxidative effect of iron on the mechanisms involved in neural plasticity.     

Crustose coralline algal species host distinct bacterial assemblages on their surfaces

Crustose coralline algae (CCA) are important components of many marine ecosystems. They aid in reef accretion and stabilization, create habitat for other organisms, contribute to carbon sequestration and are important settlement substrata for a number of marine invertebrates. Despite their ecological importance, little is known about the bacterial communities associated with CCA or whether differences in bacterial assemblages may have ecological implications. This study examined the bacterial communities on four different species of CCA collected in Belize using bacterial tag-encoded FLX amplicon pyrosequencing of the V1–V3 region of the 16S rDNA. CCA were dominated by Alphaproteobacteria, Gammaproteobacteria and Actinomycetes. At the operational taxonomic unit (OTU) level, each CCA species had a unique bacterial community that was significantly different from all other CCA species. Hydrolithon boergesenii and Titanoderma prototypum, CCA species that facilitate larval settlement in multiple corals, had higher abundances of OTUs related to bacteria that inhibit the growth and/or biofilm formation of coral pathogens. Fewer coral larvae settle on the surfaces of Paragoniolithon solubile and Porolithon pachydermum. These CCA species had higher abundances of OTUs related to known coral pathogens and cyanobacteria. Coral larvae may be able to use the observed differences in bacterial community composition on CCA species to assess the suitability of these substrata for settlement and selectively settle on CCA species that contain beneficial bacteria.     

Two new species of Achaeta (Enchytraeidae, Oligochaeta) from meadow and pasture soils of Germany

Two new, closely related species of the genus Ackaeta, A. urbana sp.n. and A. microcosmi sp.n. , (Enchytraeidae, Oligochaeta) from meadow and pasture soils of Berlin and Frankfurt (Germany) are described. Both show the same form and length/width ratio of the seminal funnel and the same general shape of the spermathecal system. They are distinguishable by distributions of epidermal sacs: only dorsal (A. microcosmi) or dorsal and ventral (A. urbana) . Also the origin of the dorsal blood vessel is different.     

Root growth in seedlings of annual pasture species

Summary The mean rate at which roots of 12 annual pasture species penetrated a yellow sand to a depth of 80 to 90 cm varied from 0.8 to 3.2 cm per day.Penetration rate was closely correlated with seed weight until roots reached a depth of about 20 cm. Thereafter rates became progressively less dependent on seed size.Penetration rate varied with time. In six species a minimum rate was reached at a depth of 18 to 24 cm. In two species rhythmic fluctuations in root penetration rate appeared to be associated with the development of new leaves on the shoot.Shading the shoots substantially reduced root penetration rate but the rhythmic fluctuations persisted. These observations are consistent with the hypothesis that the rate of root penetration is determined by the supply of metabolites to the root system.     

The condensed tannins of pasture legume species

Condensed tannins have been isolated from legume pasture species and purified by gel chromatography on Sephadex G-50 and LH-20 media. Molecular size di     

Iron availability in plant tissues-iron chlorosis on calcareous soils

The article describes factors and processes which lead to Fe chlorosis (lime chlorosis) in plants grown on calcareous soils. Such soils may contain high HCO₃ ^- concentrations in their soil solution, they are characterized by a high pH, and they rather tend to accumulate nitrate than ammonium because due to the high pH level ammonium nitrogen is rapidly nitrified and/or even may escape in form of volatile NH₃. Hence in these soils plant roots may be exposed to high nitrate and high bicarbonate concentrations. Both anion species are involved in the induction of Fe chlorosis.Physiological processes involved in Fe chlorosis occur in the roots and in the leaves. Even on calcareous soils and even in plants with chlorosis the Fe concentration in the roots is several times higher than the Fe concentration in the leaves. This shows that the Fe availability in the soil is not the critical process leading to chlorosis but rather the Fe uptake from the root apoplast into the cytosol of root cells. This situation applies to dicots as well as to monocots. Iron transport across the plasmamembrane is initiated by Fe^III reduction brought about by a plasmalemma located Fe^III reductase. Its activity is pH dependent and at alkaline pH supposed to be much depressed. Bicarbonate present in the root apoplast will neutralize the protons pumped out of the cytosol and together with nitrate which is taken up by a H⁺/nitrate cotransport high pH levels are provided which hamper or even block the Fe^III reduction.Frequently chlorotic leaves have higher Fe concentrations than green ones which phenomenon shows that chlorosis on calcareous soils is not only related to Fe uptake by roots and Fe translocation from the roots to the upper plant parts but also dependent on the efficiency of Fe in the leaves. It is hypothesized that also in the leaves Fe^III reduction and Fe uptake from the apoplast into the cytosol is affected by nitrate and bicarbonate in an analogous way as this is the case in the roots. This assumption was confirmed by the highly significant negative correlation between the leaf apoplast pH and the degree of iron chlorosis measured as leaf chlorophyll concentration. Depressing leaf apoplast pH by simply spraying chlorotic leaves with an acid led to a regreening of the leaves.     

Mineralization of nitrogen in long-term pasture soils: effects of management

A field incubation technique with acetylene to inhibit nitrification was used to estimate net N mineralization rates in some grassland soils through an annual cycle. Measurements were made on previously long-term grazed pastures on a silty clay loam soil in S.W. England which had background managements of +/– drainage and +/– fertilizer (200 kg N ha^–1 yr^–1). The effect of fertilizer addition on mineralization during the year of measurement was also determined. Small plots with animals excluded, and with herbage clipped and removed were used as treatment areas and measurements were made using an incubation period of 7 days at intervals of 7 or 14 days through the year. Soil temperature, moisture and mineral N contents were also determined. Mineralization rates fluctuated considerably in each treatment. Maximum daily rates ranged from 1.01 to 3.19 kg N ha^–1, and there was substantial net release of N through the winter period (representing, on average, 27% of the annual release). Changes in temperature accounted for 35% of the variability but there was little significant effect of soil moisture. Annual net release of N ranged from 135 kg ha^–1 (undrained soil, no previous or current fertilizer) to 376 (drained soil, +200 kg N ha^–1 yr^–1 previous and current fertilizer addition). Addition of fertilizer N to a previously unfertilized sward significantly increased the net release of N but there was no immediate effect of withholding fertilizer on mineralization during the year in which measurements were made.     

Distribution of Plectidae (Nematoda: Araeolaimida) in pasture soils

Abstract

Across 88 sites 9 species were found, with Anaplectus granulosus at 56 sites, Plectus parietinus at 47, P. longicaudatus at 30, P. parvus at 15, P. cirratus and Wilsonema otophorum at 11, P. armatus and A. porosus at 4, and Tylocephalus auriculatus at 1 site. A key to Anaplectus males is given. For nine sites mean length of female A. granulosus is negatively correlated with mean annual air temperature. The most diverse fauna comprised six species in Kaitoke silt loam; it appears that faunal diversity increases with higher rainfall. Species apparently coexist through separation in size and time. Tylocephalus was only found in soils with a thermic soil temperature regime.     

Inviting trouble: Introduced pasture species in northern Australia

Abstract I surveyed the history of exotic pasture introductions in northern Australia to compare the rate of introduction of useful species with that of weeds. Between 1947 and 1985, 463 exotic grasses and legumes in at least 2033 accessions were intentionally introduced into the region, the grasses predominantly from Africa, and the legumes from Central and South America. Of these, only 21 (5%) came to be recommended as useful, while 60 (13%) became listed as weeds. Seventeen of the useful plants were in fact also weeds, leaving only 4 species (<1%) that were useful without causing weed problems. They were far outnumbered by the 43 species (9%) that were weeds but had no recorded use. Of the 60 weeds, 21 were weeds of cropping, 20 were weeds of conservation and 19 were weeds of both sectors. Thirteen were listed as major crop weeds. Growth rate, maximum height, seed size, and continent of origin were unrelated to weediness. Good predictors of weediness were whether a plant was useful, a good performer in trials, or persisted at a field site. In addition, grasses were more likely, and legumes less likely, to be weedy than expected. It is argued that a new form of assessment is required before an exotic plant species is released into the Australian environment as a pasture plant. This would recognize that a successful introduction is almost certain to become a weed in some situations, and would attempt to assess the net national benefit of the proposed introduction.     

Trichoderma species for biocontrol of soil-borne plant pathogens of pasture species

Soil-borne plant pathogens such as Rhizoctonia solani (Kuhn), Pythium ultimum (Trow) and Sclerotinia trifoliorum (Eriks) can reduce grass and forage legume establishment. The potential for biocontrol of these pathogens by Trichoderma fungi was evaluated. Following dual culture assays, nine Trichoderma isolates (five of Trichoderma atroviride and one each of Trichoderma hamatum, Trichoderma koningiopsis, Trichoderma viride and Trichoderma virens) were chosen for assessment in pot experiments. In the presence of R. solani, perennial ryegrass (Lolium perenne L.) emergence was increased by 60–150% by two isolates of T. atroviride and by 35–212% by the isolate of T. virens, with the increase depending on growing medium and amount of pathogen inoculum. Red clover (Trifolium pratense L.) emergence in the presence of S. trifoliorum was significantly increased by two T. atroviride isolates and the T. hamatum isolate. In the presence of P. ultimum, white clover (Trifolium repens L.) emergence was increased by 25–42% by one isolate of T. atroviride and the T. hamatum isolate. However, for all three pasture species, some Trichoderma isolates reduced seedling emergence. Seedling growth (shoot and root fresh weight/plant) of the three pasture species was significantly increased by one or more T. atroviride isolates. On the basis of these results for both disease reduction and growth promotion, four T. atroviride isolates were selected for field assessment as biocontrol agents of soil-borne pathogens of pasture species.     

Iron deficiency in obese postmenopausal women

Objective: This study evaluates whether the iron deficiency suggested in children and adolescents with overweight is also present with increasing age. Research Methods and Procedures: We examined 50 consecutive postmenopausal nondiabetic white women with a BMI ≥30 kg/m² and 50 non‐obese seemingly healthy women as a control group. In addition to the traditional indices of iron status, we measured the soluble transferrin receptor (sTfR) levels, a sensitive and highly quantitative indicator of early iron deficiency not influenced by the acute phase response. Results: Obese women have higher serum sTfR levels than control subjects [1.38 (range, 0.89 to 2.39) vs. 1.16 mg/dL (range, 0.69 to 2.03 mg/dL); p < 0.001]. However, no difference in ferritin concentration was observed between the groups [70.50 (range, 18 to 219) vs. 69.50 ng/mL (range, 24 to 270 ng/mL); p = not significant]. A positive correlation between BMI and sTfR concentration was detected. On multiple regression analyses, BMI (positively) and ferritin (inversely) were independent predictors accounting for sTfR. Discussion: These results suggest that a moderate degree of iron deficiency is also present among adult women with obesity. The determination of sTfR is useful in the evaluation of iron status in this condition. Further studies with a greater number of patients are required to investigate the relationship between tissue iron concentrations and obesity.     

亚热带山地草地退化系列上种群更新研究

从种子库,幼苗和种子雨等方面对亚热带山地草地退化系列上5种植物的种群更新进行了研究,结果表明：（1）引入种多年生黑麦草（Lolium perenne)和白三叶（Trifolium repens)种群在轻度和中度退化条件下能够正常更新,但不能忍受草地进一步的退化;（2）本地种对草地退化的胁迫表现出较强的承受能力。簇生卷耳（Cerastium caespitosum)、箭叶蓼（Polygonum sagittatum)和华蒲公英（Taraxacum sinicum)的种群更新分别在中度、重度和极度退化草地上处于最佳状态;（3）若要防治草地退化,就应当地引入种的种群更新受到抑制时采取有效措施。