Respiratory components in acidophilic bacteria that respire on iron

Abstract

Microorganisms capable of aerobic respiration on ferrous ions are spread throughout eubacterial and archaebacterial phyla. Phylogenetically distinct organisms were shown to express spectrally distinct redox‐active biomolecules during autotrophic growth on soluble iron. A new iron‐oxidizing eubacterium, designated as strain Funis, was investigated. Strain Funis was judged to be different from other known iron‐oxidizing bacteria on the bases of comparative lipid analyses, 16S rRNA sequence analyses, and cytochrome composition studies. When grown autotrophically on ferrous ions, Funis produced conspicuous levels of a novel acid‐stable, acid‐soluble yellow cytochrome with a distinctive absorbance peak at 579 nm in the reduced state.

Stopped‐flow spectrophotometric kinetic studies were conducted on respiratory chain components isolated from cell‐free extracts of Thiobacillus ferrooxidans. Experimental results were consistent with a model where the primary oxidant of ferrous ions is a highly aggregated c‐type cytochrome that then reduces the periplasmic rusticyanin. The Fe(II)‐dependent, cytochrome c‐catalyzed reduction of the rusticyanin possessed three kinetic properties in common with corresponding intact cells that respire on iron: the same anion specificity, a similar dependence of the rate on the concentration of ferrous ions, and similar rates at saturating concentrations of ferrous ions     

Detection of genetic variants affecting cattle behaviour and their impact on milk production: a genome‐wide association study

Behaviour traits of cattle have been reported to affect important production traits, such as meat quality and milk performance as well as reproduction and health. Genetic predisposition is, together with environmental stimuli, undoubtedly involved in the development of behaviour phenotypes. Underlying molecular mechanisms affecting behaviour in general and behaviour and productions traits in particular still have to be studied in detail. Therefore, we performed a genome‐wide association study in an F₂ Charolais × German Holstein cross‐breed population to identify genetic variants that affect behaviour‐related traits assessed in an open‐field and novel‐object test and analysed their putative impact on milk performance. Of 37 201 tested single nucleotide polymorphism (SNPs), four showed a genome‐wide and 37 a chromosome‐wide significant association with behaviour traits assessed in both tests. Nine of the SNPs that were associated with behaviour traits likewise showed a nominal significant association with milk performance traits. On chromosomes 14 and 29, six SNPs were identified to be associated with exploratory behaviour and inactivity during the novel‐object test as well as with milk yield traits. Least squares means for behaviour and milk performance traits for these SNPs revealed that genotypes associated with higher inactivity and less exploratory behaviour promote higher milk yields. Whether these results are due to molecular mechanisms simultaneously affecting behaviour and milk performance or due to a behaviour predisposition, which causes indirect effects on milk performance by influencing individual reactivity, needs further investigation.     

Influence of latitude, water depth, day v. night and wet v. dry periods on the species composition of reef fish communities in tropical Western Australia

Trap sampling over reefs in deep (mean = 20 m) and shallow (mean = 10 m) waters along c. 1500 km of coastline in tropical north‐western Australia during both day and night and in wet and dry periods yielded 23 377 fishes, representing 32 families, 58 genera and 119 species. Individuals of the Serranidae, Lutjanidae, Lethrinidae and Carangidae contributed 88·9% to the total catch. The ichthyofaunal compositions of the Kimberley, Canning and Pilbara bioregions were relatively discrete. Species composition was influenced far more by location (latitude) than by water depth, period and time of day, and underwent a gradational change southwards. The latter change reflected differences in the trends exhibited by the relative abundances of certain species with increasing latitude and the confinement of other species largely to particular regions. The three most abundant species, i.e. Lethrinus sp. 3, Lutjanus carponotatus and Lethrinus laticaudis contributed 34·8, 20·8 and 11·6% to the total catch, respectively. The first species was rarely recorded in the two most northern locations and was abundant in the four most southern locations, whereas the last two species were relatively more abundant in northern than in southern locations. Lutjanus bitaeniatus and Lutjanus johnii were found exclusively at the two locations in the Kimberley region, whereas Abalistes stellatus, Pentapodus emeryii and Lethrinus nebulosus were not caught in this region but were found in both locations of the Canning and Pilbara regions. The species composition in deep and shallow waters at each location almost invariably differed significantly between day and night and between dry and wet periods, with species such as L. bitaeniatus, L. johnii, Lutjanus sebae and A. stellatus being more abundant over deep reefs, whereas L. carponotatus, L. laticaudis, Siganus fuscescens and Lethrinus lentjan were more numerous over shallow reefs. Species such as L. johnii and Lethrinus atkinsoni were relatively more important in night‐time than daytime catches, whereas the reverse applied to Lethrinus lentjan, L. laticaudis and Choerodon cyanodus. Lethrinus sp. 3 and L. laticaudis were relatively more important in catches during the dry than wet period.     

Detection of CaMV gene I and gene VI protein products in vivo using antisera raised to COOH-terminal β-galactosidase fusion proteins

Specific antisera were prepared to the inclusion body protein (gene VI product) and the gene I product of cauliflower mosaic virus (CaMV). Translational fusions between the lacZ gene and gene VI or gene I were constructed by cloning the relevant DNA fragments into the expression vectors pUR290, pUR291 or pUR292. Large amounts of fusion protein were synthesized when the inserted DNA fragment was in frame with the lacZ gene of the expression vector. These fusion proteins were used to raise specific antisera to gene VI and gene I proteins of CaMV. Antiserum to the gene VI product detected a range of proteins in crude extracts and in a subcellular fraction enriched for virus inclusion bodies. This range of proteins was further shown to be related to gene VI by Staphylococcus aureus V8 partial proteolysis. Antiserum to the gene I product detected viral specific proteins of 46, 42 and 38 K in preparations of CaMV replication complexes from infected plants but not in any other subcellular fraction.     

Cladocera in space and time: Analysis of lake sediments

Shells of Bosminidae and Chydoridae are quantitatively preserved in lake sediments. The chronological deposition of these remains provides the means for longterm observation of these Cladocera, both in terms of species and communities. Chydorid analysis, as based on subfossil assemblages, is an analysis of community and provides direct observation of community dynamics over extended periods of time. It has proved to be a valuable method to obtain information on the influence of environmental factors and time on community characteristics. Morphological variation inBosmina (Eubosmina) has been followed for some thousand years. This is of special interest for the evaluation of taxonomic rank (species, forms) if closely related taxa have co-existed. Bosmina successions, as well as shifts in the chydorid fauna, are related to environmental change. Thus, cladoceran analysis of lake sediments provides information on the developmental history of lakes and allows observation of the effects of longterm environmental changes, such as climatic changes and eutrophication.     

Community metabolism on rocky-shore assemblages in a mesocosm: A. Fluctuations in production,respiration, chlorophyll a content and C:N ratios of grazed and non-grazed assemblages

Studies were undertaken with the aim of developing a standardized method for assessing environmental pollution in sediments by utilization of life-history data of freshwater tubificids. Similar bioassay methods have long been used for Daphnia magna, species of Ceriodaphnia and Nitocra, etc. in accordance with guidelines from the International Organization for Standardization (ISO). Tubifex tubifex was found to be the most likely candidate for such bioassays, since the species is readily kept in culture and reproduces more or less consistantly.The culturing method is slightly modified from Kosiorek (1974). This paper provides an example of the particular sensitivity of this kind of bioassay method in the detection of heavy metal contamination of lake sediments. Sediments from the oligotrophic Lake Runn were considered suitable for the purpose, since the lake receives waste water from a major mining industry in Sweden. Metal analyses of the sediments had revealed the agents likely to be causing the decreased biological activity measured in the lake; rough amplitudes for mercury: 800–3600 ng · g^-1 dw, copper: 800–1800 g · g^-1 dw, zinc: 3.3 – 8.1 mg · g g^-1 dw have been estimated for surficial sediments.Young tubificids exposed to Lake Runn sediments did not grow much and died off within a short period of time. No reproduction occurred. Sediments from Lake Runn, when mixed with sediments from the eutrophic Lake Hjälmaren, made reproduction of T. tubifex occur only in mixtures containing less than 50% L. Runn sediments. The growth rate, reproductive success and the very timing of consecutive reproductive events of cohort individuals were found to be highly indicative of toxic effects. When additional food sources were available, however, these effects were largely masked. Therefore, extra food rations were excluded from the original method.     

Holocene sedimentary history of some coastal plains in Hokkaido,Japan IV. Diatom assemblages in the sediments from Kushiro moor (2)

Diatom assemblages of sediments obtained from three sites on Kushiro Moor were analyzed to investigate the Holocene sedimentary history. The results showed that: 1) The Takkobu site was originally at the bottom of the paleo-Kushiro Bay, and after-wards the paleo-Takkobu Lagoon developed, became sealed off, and changed to a freshwater lake. The succession to peat moor probably began about 2000 yr B.P. at the Takkobu site. 2) The Tsurui site was originally at the bottom of the paleo-Kushiro Bay, then changed to the paleo-Kushiro Lagoon and became peat moor as a result of the first Holocene regression, which finished about 3600 yr B.P. The site then returned to a brackish lake again, probably due to the second Holocene transgression between 3600 and 3000 yr B.P., thereafter passing through brackish lake and freshwater lake stages, and eventually becaming peat moor at about 2000 yr B.P., 3) At the Chuo site, the second paleo-Kushiro Bay developed again as a result of the second Holocene transgression, which finished about 3000 yr B.P. Thereafter, brackish or freshwater lakes, rivers, and then peat moor developed in the central area of Kushiro Moor. 4) The second marine diatom zone (MD₂ Zone), which indicates the second Holocene transgression, complete by about 3000 yr B.P., is detected only at the Chuo site in the central area of Kushiro Moor.     

Biotransformations Of Fluoroaromatic Compounds: Accumulation Of Hydroxylated Products From 3-Fluorophthalic Acid Using Mutant Strains Of Pseudomonas Testosteroni

Biotransformations of 3-fluorophthalic acid have been investigated using blocked mutants of Pseudomonas testosteroni that are defective in the metabolism of phthalic acid (benzene-1,2-dicar-boxyfic acid). Mutant strains were grown with L-glutamic acid in the presence of 3-fluorophthalic acid as inducer of phthalic acid catabolic enzymes. Products that accumulated in the medium were isolated, purified and identified as the fluoroanalogues of those produced from phthalic acid by the same strains. The previously undescribed fluorochemicals cis-3-fluoro-4,5-dihydro-4,5-dihydroxyphthalic acid (VI) and 3-fluoro-4,5-dihydroxyphthalic acid (VII) have been obtained by biotransformation of 3-fluorophthalic acid, and 3-fluoro-5-hydroxyphthalic acid (X) from (VI) by freeze drying. In addition, samples of 2-fluoro-3,4-dihydroxybenzoic acid (2-fluoroprotocatechuic acid, VIII) and 3-fluoro-4,Sdi-hydroxybenzoic acid (5-fluoroprotocatechuic acid, IX) were obtained with a mutant deficient in the ring-fission enzyme, showing that the fluorine substituent in their precursor substrate (VII) is not recognized by the decarboxylase of the pathway, which shows no preference for which carboxyl group is removed. These studies of 3-fluorophthalic acid catabolism demonstrate the opportunities available for the production of novel fluorochemicals in reasonable yields by microbial transformations.     

农业生态系统中新物种引进的初步探讨

在现有的农业生态系统中,引进某些新物种,往往可以使整个系统的功能发生变化。如果新物种引进得当,则可产生良好的效果,系统功能得以改善,效益提高;反之,则会造成人力、物力、财力的损失,削弱系统的功能,甚至可能遗患无穷。因此,对农业生态系统中