Mobility of iron in the estuaries of the Rhine and the Ems relevant to plant-availability problems

Studies were undertaken to obtain information on the iron mobilization processes in the sediments of the rivers Rhine and Ems, both located in western Europe. On their way from the fresh-water tidal area to the marine environment these sediments loose a considerable amount of their iron. The iron is released from the sediment by means of biodegradation products of the organic matter which dissolve the iron as organic iron complexes. The major functional groups of these organic compounds responsible for the iron mobilization are carboxyls and phenolic hydroxyls. From the sediments of the river Ems greater amounts of organic iron compounds are dissolved than from sediments of the river Rhine. Also fewer organic compounds are released from marine sediments than from fresh-water sediments, which indicates a diminished iron mobility in the marine area of the delta. Besides this the organic compounds from the marine sediments show an impoverishment in their functional groups. The sediments of the rivers Rhine and Ems are also distinguished by a different occupation of functional groups in the organic compounds. On account of a number of experiments the mobilization capacity of these river systems have been discussed.From a viewpoint of plant nutrition the mobility of iron in deposits of different ripening stages was also investigated.     

Microbial production of organic acids: expanding the markets

Microbial production of organic acids is a promising approach for obtaining building-block chemicals from renewable carbon sources. Although some acids have been produced for some time and in-depth knowledge of these microbial production processes has been gained, further microbial production processes seem to be feasible, but large-scale production has not yet been possible. Citric, lactic and succinic acid production exemplify three processes in different stages of industrial development. Although the questions being addressed by current research on these processes are diverging, a comparison is helpful for understanding microbial organic acid production in general. In this article, through analysis of the current advances in production of these acids, we present guidelines for future developments in this fast-moving field.     

Pyrazole derivatives from azines of substituted phenacyl aryl/cyclohexyl sulfides and their antimycobacterial activity

Azines derived from substituted phenacyl aryl/cyclohexyl sulfide on treatment with excess phosphorous oxychloride in N,N-dimethylformamide have been found to yield two isomeric pyrazoles in each case. A plausible mechanism has been suggested for the formation of the products. The antimycobacterial activity of the isomeric compounds has been tested against Mycobacterium tuberculosis (MTB).     

Synthesis of novel 2,3-dihydro-1,4-dioxino[2,3-g]quinoline derivatives as potential antitumor agents

New dioxinoquinolines (1-8) have been synthesized and their antiproliferative properties have been tested against several cell lines. The treatment of the 6-acetamido-2,3-dihydro-1,4-benzodioxine (10) with phosphorous oxychloride in the presence of DMF leads to a mixture of linear and angular tricyclic compounds. The key intermediates were modified and cyclized giving the corresponding dioxinoquinolines. In general, these compounds have a moderate citotoxycity.     

Role of phyllosphere fungi of forest trees in the development of decomposer fungal communities and decomposition processes of leaf litter

The ecology of endophytic and epiphytic phyllosphere fungi of forest trees is reviewed with special emphasis on the development of decomposer fungal communities and decomposition processes of leaf litter. A total of 41 genera of phyllosphere fungi have been reported to occur on leaf litter of tree species in 19 genera. The relative proportion of phyllosphere fungi in decomposer fungal communities ranges from 2% to 100%. Phyllosphere fungi generally disappear in the early stages of decomposition, although a few species persist until the late stages. Phyllosphere fungi have the ability to utilize various organic compounds as carbon sources, and the marked decomposing ability is associated with ligninolytic activity. The role of phyllosphere fungi in the decomposition of soluble components during the early stages is relatively small in spite of their frequent occurrence. Recently, the roles of phyllosphere fungi in the decomposition of structural components have been documented with reference to lignin and cellulose decomposition, nutrient dynamics, and accumulation and decomposition of soil organic matter. It is clear from this review that several of the common phyllosphere fungi of forest trees are primarily saprobic, being specifically adapted to colonize and utilize dead host tissue, and that some phyllosphere fungi with marked abilities to decompose litter components play important roles in decomposition of structural components, nutrient dynamics, and soil organic matter accumulation.     

Delivery of Complex Organic Compounds from Evolved Stars to the Solar System

Stars in the late stages of evolution are able to synthesize complex organic compounds with aromatic and aliphatic structures over very short time scales. These compounds are ejected into the interstellar medium and distributed throughout the Galaxy. The structures of these compounds are similar to the insoluble organic matter found in meteorites. In this paper, we discuss to what extent stellar organics has enriched the primordial Solar System and possibly the early Earth.     

Action of juvenoids on metamorphosis of the honey-bee, Apis mellifera

The morphogenetic action of several structurally unrelated bioanalogues of juvenile hormone resulted in two different types of effects: (1) Topical application of these compounds on worker bee larvae prior to the cessation of feeding induced development of imaginal structures characteristic for queen individuals and (2) administration of the compounds at later stages caused inhibition of differentiation of imaginal characters at various phases of adult development. The moment of application appeared to be crucial for the extent and quality of these effects. Effects on pupal morphogenesis were not proved unequivocally, since the formation of a second pupal cuticle was not observed. The juvenile hormone activities of 33 chemicals representing several types of hormonally active agents have been compared and some principal structure-activity relationships have been outlined.     

滩涂底栖动物有机污染生态学研究进展

底栖动物由于对有机污染物具有较强的吸收能力,再加上其移动能力较差、生活方式比较固定,而被广泛运用于滩涂有机污染的研究.目前这些研究主要集中在如下几个方面：（1）有机污染物在底栖动物体内的分布特征及在底栖食物链中的动力学研究;（2）底栖动物对有机污染物的生理响应研究;（3）污染物对底栖动物群落组成和结构影响研究;（4）底栖动物在滩涂有机污染检测中的应用研究.研究结果表明：滩涂底栖动物对有机污染物的累积具有选择性和季节波动性;有机污染物可以在底栖食物链中传递;底栖动物体内的有机污染物成分和含量可以有效地指示其生存环境的有机污染状况;底栖动物的混合功能氧化酶和抗氧化酶系统对体内有机污染物的累积产生积极的响应;有机污染物对底栖动物的免疫系统造成不利影响,并对遗传物质造成破坏;有机污染对底栖动物的群落组成和结构具有显著的影响.     

ISOLATION AND PURIFICATION OF CHOLINERGIC RECEPTOR PROTEOLIPIDS FROM RAT GASTROCNEMIUS TISSUE1

Four organic solvent extraction methods have been used to isolate receptor proteolipids from rat gastrocnemius tissue. The resulting proteolipids have high binding capacities and specificities for a number of cholinergic ligands including acetylcholine, α-bungarotoxin. tubocurarine and deca-methonium. The proteolipids have been purified by repeated Sephadex LH-20, Sepharose-CL and affinity chromatography in organic solvent systems. Protein, carbohydrate and lipid phosphorous analysis of the receptors throughout the purification procedure show that the relative proportions of these components varied with extraction method. The purified receptor proteolipid resulting from wet tissue extraction has been characterized as a somatic, nicotinic cholinergic receptor by its specificity and binding kinetics toward a variety of drugs and toxins. The presence of carbohydrate in the receptor proteolipid preparations throughout the purification procedure may indicate that the cholinergic receptor from rat gastrocnemius tissue is a glycoproteolipid.     

Recent developments on biological nutrient removal processes for wastewater treatment

The need for preserving the environment is tightening regulations limiting the discharge of contaminants into water bodies. Nowadays most of the effort is done on the removal of more specific contaminants such as nutrients (N and P) and sulfurous compounds since they are becoming of great concern due to its impact on the quality of water bodies. There have been two recent discoveries of microbial conversions of nitrogenous compounds. One consisting on the capability of ammonia oxidizers of denitrify under certain conditions resulting in a new one-step method for the removal of N-compounds. The second has been named the ANAMMOX process, wherein ammonium is oxidized to dinitrogen gas with nitrite as the electron acceptor. Other developments consist of operational strategies aiming at obtaining the highest efficiency at removing nitrogen at lowest cost. One strategy consists of the partial nitrification to nitrite (only successful in the SHARON process) and subsequently either the heterotrophic denitrification of nitrites or its autotrophic reduction by ANAMMOX microorganisms. Another strategy consists of the coexistence of nitrifiers and denitrifiers in the same reactor by implementing high frequency oscillations on the oxygen level.The recent developments on biological phosphorous removal are based on the capacity of some denitrifying microorganisms to store ortho-phosphate intracellular as poly-phosphate in the presence of nitrate. These microorganisms store substrate (PHB) anaerobically which is further oxidized when nitrate is present. By extracting excess sludge from the anoxic phase, phosphate is removed from the system. Removing phosphate using nitrate instead of oxygen has the advantage of saving energy (oxygen input) and using less organic carbon.The microbial conversions of sulfurous compounds involve the metabolism of several different specific groups of bacteria such as sulfate reducing bacteria, sulfur and sulfide oxidizing bacteria, and phototrophic sulfur bacteria. Some of these microorganisms can simultaneously use nitrate, what has been reported as autotrophic denitrification by sulfur and sulfide oxidizing microorganisms. More recently, the anaerobic treatment of an industrial wastewater rich in organic matter, nitrogen and sulfate, reported a singular evolution of N and S compounds that initially was hypothesized as SURAMOX (SUlfate Reduction and AMmonia OXidation). The process could not have been verified nor reproduced and further investigations on the proposed SURAMOX mechanism have given no additional insights to those initial observations.     

Release of plant-borne flavonoids into the rhizosphere and their role in plant nutrition

Plants release a multitude of organic compounds into the rhizosphere, some of which are flavonoids. These products of secondary metabolism are mainly studied for their antioxidant properties and for their role in the establishment of rhizobium-legume symbiosis; however, it has been recently demonstrated that flavonoids can also affect nutrient availability through soil chemical changes. This review will give an overview of the types and amounts of flavonoids released by roots of different plant species, as well as summarize the available knowledge on root exudation mechanisms. Subsequently, factors influencing their release will be reported, and the methodological approaches used in the literature will be critically described. Finally, the direct contribution of plant-borne flavonoids on the nitrogen, phosphorous and iron availability into the rhizosphere will be discussed.     

Methylotrophic bacteria in sustainable agriculture

Excessive use of chemical fertilizers to increase production from available land has resulted in deterioration of soil quality. To prevent further soil deterioration, the use of methylotrophic bacteria that have the ability to colonize different habitats, including soil, sediment, water, and both epiphytes and endophytes as host plants, has been suggested for sustainable agriculture. Methylotrophic bacteria are known to play a significant role in the biogeochemical cycle in soil ecosystems, ultimately fortifying plants and sustaining agriculture. Methylotrophs also improve air quality by using volatile organic compounds such as dichloromethane, formaldehyde, methanol, and formic acid. Additionally, methylotrophs are involved in phosphorous, nitrogen, and carbon cycling and can help reduce global warming. In this review, different aspects of the interaction between methylotrophs and host plants are discussed, including the role of methylotrophs in phosphorus acquisition, nitrogen fixation, phytohormone production, iron chelation, and plant growth promotion, and co-inoculation of these bacteria as biofertilizers for viable agriculture practices.     

Distributional characteristics in fractionation of phosphorus in a coral reef sedimentary environment

Abstract

This paper focuses on the distribution of an important micronutrient element, phosphorus in the various coral reef sedimentary environments of the Lakshadweep Archipelago, in the Indian Ocean. One of the salient features observed is the high concentration of organic and residual phosphorous compared to inorganic phosphorous. This is particularly evident at stations characterised by higher total phosphorous concentrations. The concentrations of total phosphorous decrease with depth because of the upward migration of phosphate produced by mineralization of organic phosphorous and also as a result of the reduction of iron oxides to which phosphate is adsorbed. Among the inorganic forms, the major contribution towards total phosphorous pool was from calcium bound phosphorous. Sedimentary pH was not found to be a decisive factor in the distributional features of phosphorous forms in the surficial stations as well as in the core profile. In this study, organic carbon displayed co-variability with silty clay or fine sandy texture of the sediment. In most of the stations, organic carbon showed poor co-variance with organic and residual phosphorous form. This shows that major contribution towards organic and residual phosphorous form is from the residual fraction comprising biologically resistant or non-available phosphorous form composed of refractory materials.     

Exploration of antimicrobial potential in LAB by genomics

A tremendous flow of information has been created through various genome sequencing projects worldwide. So far, 128 bacterial genome sequences have been completed and 391 are under way. Many of these bacteria, including several lactic acid bacteria (LAB), are used in the production and preservation of food and feed. The major antimicrobial and biopreservative substance produced by LAB is organic acid; however, some LAB produce additional antimicrobial compounds. Among these, the bacteriocins have demonstrated great potential as food preservatives. Additionally, antimicrobial compounds different from the bacteriocins have recently been identified, of which several display strong antifungal activity. The information obtained from genomics and related technologies will have great impact on the future identification and development of new antimicrobial agents. Developments will include the identification of pathways for the production of antimicrobials and genome mining for new antimicrobial peptides.     

Proteomics and the blood–brain barrier: how recent findings help drug development

The drug discovery and development processes are divided into different stages separated by milestones to indicate that significant progress has been made and that certain criteria for target validation, hits, leads and candidate drugs have been met. Proteomics is a promising approach for the identification of protein targets and biochemical pathways involved in disease process and thus plays an important role in several stages of the drug development. The blood–brain barrier is considered as a major bottleneck when trying to target new compounds to treat neurodegenerative diseases. Based on the survey of recent findings and with a projection on expected improvements, this report attempt to address how proteomics participates in drug development.     

Review of organic matter in the Orgueil meteorite

The Orgueil meteorite is a carbonaceous chondrite containing about 3.1% carbon, 5.5% sulfur and 19.9% water. Virtually all of the carbon is present as organic carbon although only about 20% is soluble in common organic solvents; the remainder is in the form of a highly substituted, irregular and aromatic polymer. Detailed methods of analysis have been improved in the past ten years sufficient for the detection of individual compounds in most of the following classes of organic compounds: hydrocarbons, oxygen-, sulfur- and nitrogen-containing organic compounds, optically active species, isotopes, bacteria and organized elements. Ten series of homologous compounds have been observed in the aliphatic hydrocarbons.In the 1950's, when interest was renewed in the Orgueil meteorite, the analytical capabilities may have given a bias toward biogenic agencies for the formation of the organic matter found in the meteorites. Some of the key biochemical compounds for extraterrestrial life are present. There is doubt, however, that these particular compounds are truly indigenous. The possibility that the indigenous organic compounds in the meteorite are present as a result of abiogenic syntheses in the cosmos is becoming more generally accepted.     

Energy source utilization by embryos and larvae of the muricid snail Chorus giganteus (Lesson, 1829)

The muricacean snail Chorus giganteus presents intracapsular development and the occurrence of nurse eggs that are ingested by the early encapsulated embryos indicate both that these snails develop through a lecitotrophic type of development and that reserves would be sufficient to support settlement and metamorphosis. In order to get more information about the use of energy resources, the dynamics of biochemical components throughout development at three temperatures (9, 12 and 15 °C) and the energetic cost of free-swimming life and metamorphosis are described. The uptake of ³H-alanine, as representative of dissolved organic matter, by embryo and larval stages is also investigated. While protein levels increased at all temperature conditions after ingestion of nurse eggs, lipids only increased when embryo and larvae were reared at 15 °C, and no change in carbohydrate levels was detected at any of the temperatures. The RNA/DNA indexes showed no significant differences with temperature at any stage of development but decreased along with the development of individuals. After hatching, organic matter and energy content of juveniles steadily decreased. Individuals at any of the developmental stage showed to be able to uptake alanine from seawater; the aminoacid uptake capacity increased along with intracapsular development. Uptake of alanine showed to be an active process and to follow Michaelis-Menten kinetics. This would be the first report about dissolved organic matter uptake by encapsulated development stages of any marine invertebrate species and let conclude that these larvae have the ability to obtain exogenous food in a dissolved form and to incorporate it into metabolizable compounds.     

Endocrine disruption in crustaceans due to pollutants: a review

The main endocrine-regulated processes of crustaceans have been reviewed in relation to the effects of endocrine-disrupting compounds (EDCs). Molting has been shown to be inhibited by several organic pollutants, such as xenoestrogens and related compounds, as well as by some pesticides. Most of these disrupters are thought to interfere with ecdysone at target tissues, although only for a few has this action been demonstrated in vitro. The heavy metal cadmium appears to inhibit some ecdysone secretion. Juvenoid compounds have also been shown to inhibit molting, likely by interfering with the stimulatory effect of methyl farnesoate. A molt-promoting effect of emamectin benzoate, a pesticide, has also been reported. As for reproduction, a variety of organic compounds, including xenoestrogens, juvenoids and ecdysteroids, has produced abnormal development of male and female secondary sexual characters, as well as alteration of the sex ratio. Cadmium and copper have been shown to interfere with hormones that stimulate reproduction, such as methyl farnesoate, as well as with secretion of the gonad inhibiting hormone, therefore affecting, for example, ovarian growth. Several heavy metals were able to produce hyperglycemia in crustaceans during short times of exposure; while a hypoglycemic response was noted after longer exposures, due to inhibition of secretion of the crustacean hyperglycemic hormone. The ecological relevance of EDCs on crustaceans is discussed, mainly in relation to the identification of useful biomarkers and sentinel species. New experimental approaches are also proposed.     

Libraries of non-polymeric organic molecules

New technology is emerging that permits the chemical synthesis of large numbers of different compounds simultaneously. Combinatorial chemistry is heavily dependent upon the adaption of organic synthesis to solid supports and has necessitated the development of appropriate analytical and chemical approaches to both monitor solid-phase reactions and release finished compounds into solution. Considerable progress has recently been made in all of these areas. Small-molecule libraries of medicinally important chemical classes, such as 1,4-benzodiazepines, mercaptopropionyl amino acids, and peptidyl phosphonates, have recently been reported. Encoded combinatorial libraries of dihydrobenzopyran-based and acylpiperidine-based pharmacophores have yielded potent inhibitors of carbonic anhydrase. Automated instrumentation is growing in importance for the synthesis of small-molecule libraries.     

A re-investigation on the ecdysteroids during embryogenesis in the desert locust, Schistocerca gregaria

Comparison of gas chromatography and high-pressure liquid chromatography methods for determination of ecdysteroids in insect eggs revealed that published values for Schistocerca gregaria were very low. The error has been traced to incomplete hydrolysis of conjugates. Revised values for the levels of ecdysone, 20-hydroxy-ecdysone and 2-deoxy-ecdysone are given here. The same general pattern of falling ecdysteroid titre during early stages of embryo development followed by an increase and a final decrease is observed. Experiments have been made on the effect of phosphate, ionic strength and a specific β-glucuronidase competitive inhibitor on the hydrolysis of the polar ecdysteroid conjugates, in an attempt to provide more evidence on the chemical nature of these compounds.