Novel principles in the microbial conversion of nitrogen compounds

Some aspects of inorganic nitrogen conversion by microorganisms like N2O emission and hydroxylamine metabolism studied by Beijerinck and Kluyver, founders of the Delft School of Microbiology, are still actual today. In the Kluyver Laboratory for Biotechnology, microbial conversion of nitrogen compounds is still a central research theme. In recent years a range of new microbial processes and process technological applications have been studied. This paper gives a review of these developments including, aerobic denitrification, anaerobic ammonium oxidation, heterotrophic nitrification, and formation of intermediates (NO2-, NO, N2O), as well as the way these processes are controlled at the genetic and enzyme level.     

The Phaff school of yeast ecology

Herman Jan Phaff's legacy includes pioneering work on the yeast cell envelope and the application of molecular approaches to yeast systematics. Clearly, his interest and knowledge spanned the whole gamut of yeast biology. Yet, his most original and most heartfelt contribution was to our understanding of the position occupied by yeasts in nature. This view developed through the juxtaposition of his childhood exposure to industrial fermentations and his training in the tradition of Beijerinck's Delft School of Microbiology. Through some of Phaff's recent writings, I have attempted to formulate the themes or principles that were implicit to his ecological thinking. Six focal points emerge. (1) Yeasts in themselves are a sufficient object of study. (2) A clear idea of a yeast community cannot be obtained unless the yeast species are correctly identified. (3) Ecologically meaningful conclusions require an adequate sample size. (4) The bacteriological dictum "everything is everywhere" is a poor account of yeast distributions. (5) The habitat is the cornerstone of yeast ecology. (6) Ecology is the most exciting aspect of yeast biology.     

Some ecological aspects of the edible oyster Crassostrea cucullata (born) occurring in association with mangroves in negombo lagoon,Sri Lanka

Ecology of an oyster population (Crassostrea cucullata (Born)), associated with the roots of Rhizophora micronata Link, on an islet in the Negombo lagoon on the west coast of Sri Lanka, was studied. The associated fauna was described.I.H.E. Oude Delft 95, Delft, Holland     

The Order of Men: the Nation and the Metropolitan Imaginary at an Indian Public School

This article is concerned with exploring discursive constructions of Indian post-coloniality and modernity. The analysis focuses upon a fully residential boys school in North India, the Doon School, which has played a historically significant role in the production of a discourse on nationhood and citizenship. Elsewhere, I have argued that the School defines its citizenship project in terms of three main ‘imaginaries’: secularism, rationality, and ‘metropolitanism’. This paper explores the construction of a narrative of the post-colonial nation-state at the School through ‘metropolitanism’.     

中国东北地区蚱属一新种(直翅目,蚱总科)

报道采自东北地区蚱总科、蚱属昆虫1新种,即长春蚱Tetrix changchunensis sp.nov.;并与其近似种做了比较,模式标本保存于东北师范大学生命科学学院动物标本室.     

50 years thymine dimer

Fifty years ago thymine dimer was discovered in the Biochemical and Biophysical Laboratory of Delft Technological University, The Netherlands, by one of the authors of this review (Beukers) as the first environmentally induced DNA lesion. It is one of the photoproducts formed between adjacent pyrimidine bases in DNA by UV irradiation, currently known as cyclobutane pyrimidine dimers (CPDs) and (6-4) photoproducts. Major lesions found in DNA after in vitro or in vivo UV irradiation are the cis-syn cyclobutane thymine dimer and the thymine-cytosine (6-4) photoproduct. Even after 50 years the study of photo-induced DNA lesions is still going on as is illustrated by the hundreds of papers published every year and the millions hits when browsing the internet for dimer-related information. Living organisms possess efficient and different mechanisms to repair detrimental lesions in their DNA. A unique mechanism to repair CPDs is reversion by either direct interaction with light of short wavelength or by enzymatic photoreactivation. Photophysical mechanisms that induce and reverse molecular bonds in biological macromolecules have been a main focus of research of the group in Delft in the middle of the last century. This review describes the break-through results of these studies which were the result of intense interactions between scientists in the fields of physics, organic chemistry and biochemistry. Philosophically, the "view" of the group in Delft was very appealing: since in nature photolesions are induced in DNA by the sun, how is it possible that repair of these lesions could be accomplished by the same energy source. Evolutionary, it is hardly possible to think of a more efficient repair mechanism.     

Still going strong: Leeuwenhoek at eighty

At age 80, Antony van Leeuwenhoek was a world-famous scientist who came from a prosperous Delft family with a heritage of public service. He continued that tradition by serving in paid municipal offices. Self-taught, he began his scientific career in his 40s, when he began making hundreds of tiny single-lens microscopes. Pioneering the use of now-common microscopic techniques, he was the first human to see microbes and microscopic structures in animals, plants, and minerals. Over 50 years, he wrote only letters, more than 300 of them, and published half of them himself. More than a hundred were published in translation in the Royal Society’s Philosophical Transactions. Today, Leeuwenhoek is considered in the lesser rank of scientists and is not well known outside of his homeland. Recent archival research in Delft has contributed new information about his life that helps to contextualize his science, but much remains to be learned.     

Saccharomyces vafer andS. inconspicuus spp.n.

During the re-examination of cultures deposited with the Yeast Division of the Centraalbureau voor Schimmelcultures, Delft, representatives of two hitherto undescribed species of the genusSaccharomyces were encountered.     

Sympodiomyces gen. n., a yeast-like organism from southern marine waters

Sympodiomyces gen. n. is described with the single speciesSympodiomyces parvus sp. n. The distinguishing characteristic of this yeast-like genus is the method of asexual reproduction: conidia are produced on a conidiophore that develops sympodially. A sexual stage has not been observed, therefore the genus is placed among the Fungi Imperfecti, family Cryptococcaceae.Contribution No. 1364 from the Rosenstiel School of Marine and Atmospheric Science, University of Miami, Florida.The authors gratefully acknowledge Dr. Jan Kohlmeyer, Univ. of North Carolina, Morehead City, North Carolina; Dr. R. T. Moore, North Carolina State Univ. at Raleigh; Dr. H. J. Phaff, Univ. of California at Davis; Miss W. Ch. Slooff and Mr. D. Yarrow, CBS, Delft, Netherlands; Dr. K.Tubaki, Institute for Fermentation, Osaka, Japan; and Dr. J. A. von Arx, C.B.S., Baarn, for examining cultures ofS. parvus. Dr. D. P. Rogers, Univ. of Illinois, Urbana, Ill, prepared the generic Latin diagnosis. Mr. Steven Y. Newell and Mr. A. Weiner, Univ. of Miami, assisted in obtainingEltanin collections. This study was supported by the National Science Foundation through the Office of Antarctic Programs Grant No. GA 13675.     

The influence of uncouplers on facilitated diffusion of sorbose in Saccharomyces cerevisiae

Sorbose uptake in Saccharomyces cerevisiae, strain Delft 1, proceeds via mediated passive transport. In the cell sorbose is distributed in at least two compartments. Efflux studies showed that sorbose uptake in one of these compartments is not readily reversible. Uncouplers of oxidative phosphorylation inhibit both transport velocity and steady-state uptake level. It could be shown that these two effects are caused by different modes of action of the uncouplers. None of these two effects could be ascribed to changes of the electrochemical H⁺ gradient or of the intracellular pH. It is suggested that the inhibition of uptake velocity is caused by binding of the uncoupler to the sorbose translocator, thus lowering the transport activity. The uncoupler binding site is probably located at the intracellular fragment of the carrier. The second effect, reduction of the steady-state uptake level, is probably due to blocking of sorbose influx into the compartment that exhibits poor reversibility.     

Modeling the influence of a young mussel bed on fine sediment dynamics on an intertidal flat in the Wadden Sea

Mussel beds are known to affect fine sediment dynamics and morphology on mudflat scale, a clear example of ecosystem engineering. Current research into possible ecological engineering applications of mussel beds makes quantitative modeling desirable. In this study a process-based model of the interaction between a young mussel bed and fine sediment was set up for use in the hydrodynamic and morphological model Delft3D-FLOW. The model encompasses the hydraulic roughness of the mussel bed, active capture of suspended sediment by filter feeding and changed bed properties due to biodeposited matter. The mussel bed implementation in Delft3D-FLOW was applied in a test case: a Wadden Sea intertidal mudflat model. It was concluded that a combination of active deposition via filtration and slow down of the flow due to increased roughness leads to high net deposition in the mussel bed. In addition, the ability of young mussels to quickly climb on top of deposited material results in rapid trapping of large amounts of fine sediment. In the wake of the mussel bed, deposition is also high because of reduced flow velocities. The effects of different existing mussel bed patterns were also evaluated. Patchiness and specifically striped patterns cause mussel beds to experience less sedimentation than uniformly covered beds of the same size and may therefore be favorable to mussels.     

Three Centuries of Protozoology: A Brief Tribute to its Founding Father,A. van Leeuwenhoek of Delft*

SYNOPSIS. It was exactly 300 years ago this month (August 1974) that the 17th century modest draper from Delft, Holland—Antony van Leeuwenhoek—discovered protozoa. Describing them, often with amazing accuracy considering the optical equipment he was using (simply a home-made “glorified”hand lens), in letters to the Royal Society of London, he established himself, certainly, as the founding father of protozoology. It is particularly appropriate for an assemblage of protozoologists to pay homage to this intrepid “philosopher in little things,”a man with an insatiable curiosity about his wee animalcules, on the tricentenary of his discovery of them, since it was an event of such long-lasting significance.     

Blood,sweat and plaster casts: Reviewing the history,composition, and scientific value of the Raymond A. Dart Collection of African Life and Death Masks

This paper addresses the history, composition and scientific value of one of the most comprehensive facemask collections in Africa, the Raymond A. Dart Collection of African Life and Death Masks. Housed within the School of Anatomical Sciences at the University of the Witwatersrand (South Africa), it comprises 1110 masks (397 life, 487 death, 226 unknown). Life masks represent populations throughout Africa; death masks predominately southern Africa. Males preponderate by 75%. Recorded ages are error prone, but suggest most life masks are those of <35 year-olds, death masks of 36+ year-olds. A total of 241 masks have associated skeletons, 209 presenting a complete skull.Life masks date between 1927 and c.1980s, death masks 1933 and 1963. This historical collection presents uncanny associations with outmoded typological and evolutionary theories. Once perceived an essential scientific resource, performed craniofacial superimpositions identify the nose as the only stable feature maintained, with the remaining face best preserved in young individuals with minimal body fat. The facemask collection is most viable for teaching and research within the history of science, specifically physical anthropology, and presents some value to craniofacial identification. Future research will have to be conducted with appropriate ethical considerations to science and medicine.     

Pollution control by wetlands

The 2nd International Symposium on Wetland Pollutant Dynamics and Control (WETPOL 2007), organised by the Department of Geography of the University of Tartu (Estonia) in co-operation with partners from the Estonian University of Life Sciences (Tartu, Estonia), Ghent University (Belgium), and the UNESCO-IHE (Delft, The Netherlands), was held 16–20 September 2007, in Tartu, Estonia. At this meeting, 140 oral presentations (including 9 keynote speeches) and 70 posters by representatives from 38 countries were presented. About half of the presentations considered purification processes in both semi-natural and constructed wetlands. The editorial paper highlights trends in studying the cycling of nitrogen, phosphorus, carbon, heavy metals, and organic pollutants in wetlands, but also in the modelling of pollutant removal and the functioning of plants in the wetland environment. It also describes the WETPOL 2007 meeting, which served as the source of the selected papers, and briefly explains the main aspects of these papers.     

Molecular and biochemical characterization of a sand fly population from Sri Lanka: evidence for insecticide resistance due to altered esterases and insensitive acetylcholinesterase

With an increasing incidence of cutaneous leishmaniasis in Sri Lanka, particularly in northern provinces, insecticide-mediated vector control is under consideration. Optimizing such a strategy requires the characterization of sand fly populations in target areas with regard to species composition and extant resistance, among other parameters. Sand flies were collected by human bait and cattle-baited net traps on Delft Island, used as an illegal transit location by many refugees returning to the north of Sri Lanka from southern India where leishmaniasis is endemic. For species identification, genomic DNA was extracted and a fragment of the ribosomal 18S gene amplified. The sequence from all flies analysed matched that of Phlebotomus argentipes Annandale & Brunetti, the primary vector in India and the most likely vector in Sri Lanka. Independent morphological analysis also identified P. argentipes. To establish the current susceptibility status of vector species, data were obtained at the biochemical level, from which potential cross-resistance to alternative insecticides can be predicted. The Delft Island collection was assayed for the activities of four enzyme systems involved in insecticide resistance (acetylcholinesterase, non-specific carboxylesterases, glutathione-S-transferases and cytochrome p450 monooxygenases), establishing baselines against which subsequent collections can be evaluated. There was preliminary evidence for elevated esterases and altered acetylcholinesterase in this population, the first report of these resistance mechanisms in sand flies to our knowledge, which probably arose from the malathion-based spraying regimes of the Anti-Malarial Campaign.     

Simulation results with stepwise mutation model and their interpretations

Summary Monte Carlo simulations are performed to compare the predictions based on the two presently used theoretical models for studying genetic variations in natural populations, the infinite allele model and the stepwise mutation model. Distribution of heterozygosity is noticed to be similar under these models until the product of population size and mutation rate is large. It is seen that electromorphs with high population frequency usually contain older alleles (at the codon level) than an electromorph of low population frequency. The interpretations of these results in explaining the allelic variations at electrophoretic level is also discussed.Research supported by U.S. Public Health Service General Research Support Grant 5 SO 5 RR 07148 from the University of Texas Health Science Center, Graduate School of Biomedical Sciences, Houston, Texas     

南中国海墨杯虫属(单殖吸虫,分室科)一新种

记述采自南中国海扁鮀鲣Auxis thazard thazard鳃上的分室科墨杯虫属单殖吸虫1新种,以宿主属名命名为鮀鲣墨杯虫Caballerocotyl aauxis sp.nov.。新种具2列背部边缘小刺,前、后吸器相对较大,后吸器腹面不具乳突,公共生殖孔开口紧邻于左前吸器下方,阴道开口于咽中部水平等特征而区别于近似种。模式标本保存于华南师范大学生命科学学院鱼类寄生虫学研究室。     

Syntaxonomic and nomenclatural treatment of Scandinavian-type associations and sociations

Abstract. The launching of international phytosociological projects requires a re-evaluation of vegetation units (syntaxa) of different phytosociological schools and their integration into one global classification system. Despite many difficulties, this possibility is offered by the floristic-phytosociological system - a hierarchical system of syntaxa defined by floristic-socio-logical criteria. Associations (and lower syntaxa) of the Zürich-Montpellier School as well as associations (later called sociations) of the Uppsala School are defined by means of the floristic composition of plant communities and fit this postulate; their syntaxonomic identity can be checked by tabular comparison of vegetation relevés. Not only the presence of diagnostic species but also the specific combination of sociological groups of species, dominance of species or even the absence of certain species or species groups can be used as syntaxonomic criteria. The syntaxonomic identification of an association of the Uppsala School with one of the Zürich-Montpellier School means uniting syntaxa of the same rank in the sense of the Code of Phytosociological Nomenclature. If a sociation is found to fit the criteria of an association delimited by the Zürich-Montpellier methods, the rank of an association can be attributed to this sociation and its name can thus be validated in the sense of the Code.     

Candida vanriji nova species a new yeast from Swedish soils

Summary A new species of Candida is described: it was isolated from soils of Sweden. This species is named Candida vanriji nova species in honour of Mrs. N. W. Kreger-Van Rij of the C. B. S. of Delft.