Impacts of tropospheric ozone and airborne nitrogenous pollutants on natural and semi-natural ecosystems: a commentary

Man's activities pose a number of threats to the functioning, structure and diversity of natural and semi-natural ecosystems. One of the main threats is the increase in concentrations in air pollutants in this century (Wellburn, 1988; Tamm, 1991). This paper is a commentary on the effects of tropospheric ozone (O₃) and airborne nitrogen deposition (both oxidized (NO_x) and reduced (NH_y) compounds) on natural and semi-natural ecosystems, based upon the oral presentations and the discussions during the Symposium, extended with a personal overview and some suggestions about future challenges for research. The most important effects of these air pollutants on natural and semi-natural vegetation are summarized and evaluated in ecological terms, with respect to the functioning and structure of unaffected systems. Air pollutants are transported over both short and long distances (as far as a few thousand km) before being deposited on surface water, vegetation or soil. In this way, vegetation over a large area or in remote regions can be influenced by airborne pollutants (see Fowler et al . (1998); Asman, Sutton & Schjørring (1998)).     

Improved detection and comparative sizing of human chromosomal telomeres in situ

Telomeric length dynamics are thought to play an important role both in the processes of cellular aging and cancer progression. We have revised the primed in situ (PRINS) labeling technique to allow an estimation of the relative length of individual telomeres. We illustrate the applicability of the approach by demonstrating different telomeric sizes not only between blood lymphocytes from a young and an old donor, but also among bone marrow cells from hematological cancer patients. In the latter case we found general variations in telomeric sizes as well as individual telomeric variations that would have escaped detection by other methods. An interesting finding was the selective expansion of a single telomere within a specific subset of cells. Received: 16 January 1998; in revised form: 16 March 1998 / Accepted: 2 April 1998     

中国南方典型地区油-稻轮作条件下大气SO2干沉降速率动态变化

以1998年11月～1999年10月中国科学院红壤生态试验站农田小气候观测站气象梯度资料(温度、风速、气压),计算近地面湍流特征参数(u^*、θ^*、L),然后采样阻力模式计算SO2干沉降速率(Vd)。研究了该地油-稻轮作条件下大气SO₂干沉降Vd动态变化．结果表明,一年中大气SO2干沉降Vd时平均年均值为0．124～0．897cm·s^-1(mean±SE=0．507±0．167cm·s^-1)．一年中大气SO2干沉降Vd存在如下规律性：白天>晚上．3～8月份SO2Vd平均值(0．611cm·s^-1)大于9～12、1～2月份SO2Vd平均值(0．401cm·s^-1)．水稻生长期间(0．605±0．093cm·s^-1)>油菜(0．491±0．166cm·s^-1)>休闲(0．342±0．174cm·s^-1)．     

Stereoisomers of 3-(2,3-dihydrobenzofuran-2-yl)quinuclidine: Preparation and muscarinic receptor affinities

The four stereoisomers of the antimuscarinic 3-(2,3-dihydrobenzofuran-2-yl)quinuclidine have been prepared by a method involving chromatographic separation of the racemic diastereoisomers as borane complexes. The relative and absolute configurations of the stereoisomers were determined by X-ray crystallographic methods. The crystal structure of (2′R,3R)-3-(2,3-dihydrobenzofuran-2-yl)quinuclidine · HCl · H₂O contains two independent molecules with different conformations of both the quinuclidine moiety and the dihydrofuran ring. Chirality 10:813–820, 1998. © 1998 Wiley-Liss, Inc.     

中国南方典型地区油-稻轮作条件下大气SO2干沉降速率动态变化

以1998年11月～1999年10月中国科学院红壤生态试验站农田小气候观测站气象梯度资料(温度、风速、气压),计算近地面湍流特征参数(u^*、θ^*、L),然后采样阻力模式计算SO₂干沉降速率(V_d),研究了该地油-稻轮作条件下大气SO₂干沉降V_d动态变化。结果表明,一年中大气SO₂于沉降V_d时平均年均值0.124～0.897cm·s^-1(mean±SE=0.507±0.167cm·s^-1).一年中大气SO₂干沉降V_d存在如下规律性:白天>晚上。3～8月份SO₂V_d平均值(0.611cm·s^-1大于9～12、1～2月份SO₂V_d平均值(0.401cm·s^-1)。水稻生长期间(0.605±0.093cm·s^-1)>油菜(0.491±0.166cm·s^-1)>休闲(0.342±0.174cm·s^-1)。     

Molecular motions and hydration of purple membranes and disk membranes studied by neutron scattering

Fast stochastic equilibrium fluctuations (time scale: 10^–10–10^–13 seconds) in purple membranes (PM) and in disk membranes (DM) have been measured with quasielastic incoherent neutron scattering. The comparison of predominantly stochastic motions occurring in purple membranes and in disk membranes revealed qualitatively similar dynamical behaviour. Models of internal motions within restricted volumes have been shown to be useful to fit the spectra from both samples. From fits using these models we found “amplitudes” 15 to 20% larger for motions in DM samples compared to PM samples. This indicates a higher internal flexibility of the DM. Because the dynamical behaviour is very sensitive to the hydration of the protein-lipid complex, we also performed neutron diffraction experiments to determine lamellar spacings as a measure of level of hydration and as a function of temperature. From these studies the interaction of solvent molecules with the surface of the protein-lipid complex appears to be qualitatively similar for both types of membranes. Received: 12 February 1998 / Revised version: 18 March 1998 / Accepted: 27 March 1998     

Prevalence of de-O-acetylated serogroup C meningococci before the introduction of meningococcal serogroup C conjugate vaccines in the United Kingdom

Meningococcal serogroup C conjugate (MCC) vaccines have been introduced in the UK to combat the rise in serogroup C meningococcal disease. Serogroup C meningococci may occur naturally expressing either O-acetylated (Oac(+)) or de-O-acetylated (Oac(-)) polysaccharide capsules. In a small study in the USA in the 1970s 15% of serogroup C meningococcal case isolates were reported to be Oac(-) though the prevalence of these Oac(-) isolates has not been recorded in the UK. This is of interest as the first MCC vaccines to be introduced are Oac(+) and the potential impact of this on Oac(-) serogroup C isolates is unclear. Serogroup C isolates submitted to the Public Health Laboratory Service Meningococcal Reference Unit in January 1998 (n=113) and January 1999 (n=162) were investigated by dot blotting using monoclonals specific for Oac(+) and Oac(-) serogroup C polysaccharides. This revealed 12% Oac(-) isolates for both January 1998 and January 1999. The proportion of fatal cases was found to similar for both Oac(-) and Oac(+), 14 and 9% for 1998 and 5 and 3% for 1999, indicating that the pathogenic potential of these Oac(-) isolates is similar to Oac(+). The acetylation status of serogroup C isolates needs to be monitored throughout and after the introduction of MCC vaccines.     

Human sperm chromosome complements in chemotherapy patients and infertile men

Our studies of human sperm karyotypes and interphase sperm analyzed by fluorescence in situ hybridization (FISH) have both yielded estimates of disomy frequencies of approximately 0.1% per chromosome with an overall aneuploidy frequency in human sperm of approximately 5%–6%. However, the distribution of aneuploidy in sperm is not even, as our data from sperm karyotypes and multicolour FISH analyses both demonstrate a significant increase in the frequency of aneuploidy for chromosome 21 and the sex chromosomes. We have studied men at increased risk of sperm chromosomal abnormalities including cancer patients and infertility patients. Testicular cancer patients were studied before and 2–13 years after chemotherapy (CT) with BEP (bleomycin, etoposide, cisplatin). Sperm karyotype analysis on 788 sperm demonstrated no significant difference in the frequency of numerical or structural chromosomal abnormalities post-CT vs pre-CT. Similarly, multicolour FISH analysis for chromosomes 1, 12, XX, YY and XY in 161,097 sperm did not detect any significant differences in the frequencies of disomy before and after treatment. However, recent evidence has suggested a significant increase in the frequency of disomy and diploidy during CT. We have found that infertile men, who would be candidates for intracytoplasmic sperm injection, have an increased frequency of chromosomally abnormal sperm karyotypes. Also, FISH analysis for chromosomes 1, 12, 13, 21, XX, YY and XY in 255,613 sperm demonstrated a significant increase in chromosomes 1, 13, 21, and XY disomy in infertile men compared with control donors. Received: 4 July 1998; in revised form: 7 September 1998 / Accepted: 8 September 1998     

cDNA cloning of luteinizing hormone subunits from brushtail possum and red kangaroo

Luteinizing hormone (LH) plays an important role in the reproductive cycles of all mammals. There is a large amount of both nucleotide and amino acid sequence data available for LH from eutherian mammals, but little is known about the primary structure of LH in marsupials. We have used consensus PCR primers to generate specific probes for screening pituitary cDNA libraries and report the cloning of the cDNAs encoding the α-subunit of LH (also shared by a number of other glycoprotein hormones) and the LH-specific β-subunit, from the common brushtail possum, Trichosurus vulpecula, and the red kangaroo, Macropus rufus. Southern blotting experiments indicated that both genes are probably present as single copies. Comparison of the deduced marsupial protein sequences with homologous sequences from other vertebrates revealed a high degree of conservation, especially for the α-subunit. These sequences represent the first complete primary structures for a marsupial glycoprotein hormone to have been elucidated. Received: 30 January 1998 / Accepted: 10 April 1998     

Evidence for and expression of a laccase gene in three basidiomycetes degrading humic acids

The majority of lignin-degrading basidiomycetes are able to depolymerize humic acids. In this presentation the relationship and possible similarities between enzymes involved in lignin degradation and humic acid depolymerization were examined on the genetic level. We have cloned fragments of the gene encoding the extracellular ligninolytic enzyme laccase from Clitocybula dusenii, Nematoloma frowardii and a fungal strain designated i63-2, and compared the three sequences with those of several other published laccase genes. The sequenced fragments displayed a high homology both on the DNA (97%–77%) and amino acid (100%–85%) level. Furthermore, the expression of this gene in the above-mentioned fungi was demonstrated by a nested polymerase chain reaction with cDNA as template. Received: 3 February 1998 / Received revision: 31 August 1998 / Accepted: 3 September 1998     

Degradation of lignite (low-rank coal) by ligninolytic basidiomycetes and their manganese peroxidase system

Ligninolytic basidiomycetes (wood and leaf-litter-decaying fungi) have the ability to degrade low-rank coal (lignite). Extracellular manganese peroxidase is the crucial enzyme in the depolymerization process of both coal-derived humic substances and native coal. The depolymerization of coal by Mn peroxidase is catalysed via chelated Mn(III) acting as a diffusible mediator with a high redox potential and can be enhanced in the presence of additional mediating agents (e.g. glutathione). The depolymerization process results in the formation of a complex mixture of lower-molecular-mass fulvic-acid-like compounds. Experiments using a synthetic ¹⁴C-labeled humic acid demonstrated that the Mn peroxidase-catalyzed depolymerization of humic substances was accompanied by a substantial release of carbon dioxide (17%–50% of the initially added radioactivity was released as ¹⁴CO₂). Mn peroxidase was found to be a highly stable enzyme that remained active for several weeks under reaction conditions in a liquid reaction mixture and even persisted in sterile and native soil from an opencast mining area for some days. Received: 31 July 1998 / Received revision: 29 September 1998 / Accepted: 2 October 1998     

Nezara viridula parasitism by the tachinid fly Trichopoda pennipes ten years after its accidental introduction into Italy from the New World

Percent parasitism of Nezara viridula (L.) (Heteroptera:Pentatomidae) by Trichopoda pennipes F.(Diptera: Tachinidae) ten years after itsfortuitous introduction was evaluated in someareas of Italy. The parasitoid is acclimatisedin central Italy with a parasitism in 1998 of21.3% in the west coast area (Lazio) and of24.8% in the inland area (Umbria). Host adultsof both sexes were attacked with the same ratein 1998, whereas this was higher in males thanfemales in 1991 and 1992. Parasitism of nymphswas lower in all three years. In 1998parasitized bugs showed 1 (54.1%) to a maximumof 15 (0.4%) macrotype eggs per individual,distributed preferentially on the thorax ascompared with other body parts. None of theother pentatomid species collected in the sameareas were parasitized by T. pennipes,indicating that there have not been indirecteffects of this fortuitous introduction tillnow.     

The Fine Structure and Function of the Anterior Foregut Glands of Cymatium Intermedius (Cassoidea: Ranellidae)

The fine structure of the salivary glands of Cymatium intermediusis described. It is concluded that both the posterior acid secretingand anterior acinous lobes are homologous with the salivaryglands of other prosobranchs. At least six different types ofsecretion have been identified and their possible roles discussed.The anterior lobes secrete mucin and proteins believed to beenzymes, and the posterior lobes are specialized for acid productionas well as secreting protein (probably a peptide toxin). Themechanisms of acid secretion and protection from damage to thesnail before its release are also considered. (Received 12 January 1998; accepted 1 March 1998)     

Cold shock and adaptation

Adaptation to environmental stresses, such as temperature fluctuation, is essential for the survival of all living organisms. Cellular responses in both prokaryotes and eukaryotes to high temperature include the synthesis of a set of highly conserved proteins known as the heat shock proteins. In contrast to the heat shock response, adaptation to low temperatures has not been as extensively studied. However, a family of cold-inducible proteins is evident in prokaryotes. In addition, most organisms have developed adaptive mechanisms that alter both membrane fluidity and the protein translation machinery at low temperature. This review addresses the different adaptive mechanisms used by a variety of organisms with a focus on the molecular mechanisms of cold adaptation that have recently been identified during the cold shock response in Escherichia coli. BioEssays 20:49–57, 1998. © 1998 John Wiley & Sons, Inc.     

Phytochrome Regulation of Expression of mRNA Encoding the Major Light-Harvesting Chlorophyll a/b-Binding Proteins of Photosystem II in the Haploid Phase of Adiantum capillus-veneris

Light regulates development in the fern Adiantum capillus-venerisduring both the haploid gametophyte and diploid sporophyte phases.In this study, we have investigated the role of the photoreceptorphytochrome in haploid spore germination and regulation of expressionof mRNA encoding the major light-harvesting polypeptides ofphotosystem II {Lhcb mRNAs). Both of these responses appearto be induced by phytochrome and inhibited by blue light, acting.throughseparate photoreceptor(s). Characteristics of phytochrome actionwere similar for both responses, showing no induction in thevery low fluence range and an ‘escape’ from far-redreversal for 50% of the response by 6 h. Overall, these resultsshow that phytochrome regulates both a morphological and a molecularprocess in haploid fern spores, and that these processes mayshare a common signal transduction pathway. (Received February 4, 1998; Accepted April 8, 1998)     

Undernutrition,subsequent risk of mortality and civil war in Burundi

The paper investigates the effect of child undernutrition on the risk of mortality in Burundi. Using anthropometric data from a longitudinal survey (1998–2007) we find that undernourished children, measured by the height-for-age z-scores (HAZ) in 1998 had a higher probability to die during subsequent years. In order to address the problem of omitted variables correlated with both nutritional status and the risk of mortality, we use the length of exposure to civil war prior to 1998 as a source of exogenous variation in a child's nutritional status. Children exposed to civil war in their area of residence have worse nutritional status. The results indicate that one year of exposure translates into a 0.15 decrease in the HAZ, resulting in a 10% increase in the probability to die. For boys, we find a 0.34 decrease in HAZ per year of exposure, resulting in 25% increase in the probability to die. For girls, the results are statistically not significant at the usual thresholds. We show the robustness of our results and we derive policy conclusion for a nutrition intervention in times of conflict.     

Bacterial dehalogenation

Halogenated organic compounds are produced industrially in large quantities and represent an important class of environmental pollutants. However, an abundance of haloorganic compounds is also produced naturally. Bacteria have evolved several strategies for the enzyme-catalyzed dehalogenation and degradation of both haloaliphatic and haloaromatic compounds: (i) Oxidative dehalogenation is the result of mono- or dioxygenase-catalyzed, co-metabolic or metabolic reactions. (ii) In dehydrohalogenase-catalyzed dehalogenation, halide elimination leads to the formation of a double bond. (iii) Substitutive dehalogenation in most cases is a hydrolytic process, catalyzed by halidohydrolases, but there also is a “thiolytic” mechanism with glutathione as cosubstrate. Dehalogenation by halohydrin hydrogen-halide lyases is the result of an intramolecular substitution reaction. (iv) A distinct dechlorination mechanism involves methyl transfer from chloromethane onto tetrahydrofolate. (v) Reductive dehalogenations are co-metabolic processes, or they are specific reactions involved in substrate utilization (carbon metabolism), or reductive dehalogenation is coupled to energy conservation: some anaerobic bacteria use a specific haloorganic compound as electron acceptor of a respiratory process. This review discusses the mechanisms of enzyme-catalyzed dehalogenation reactions, describes some pathways of the bacterial degradation of haloorganic compounds, and indicates some trends in the biological treatment of organohalogen-polluted air, groundwater, soil, and sediments. Received: 24 June 1998 / Received revision: 1 September 1998 / Accepted: 3 September 1998     

Fine-resolution mapping by haplotype evaluation: the examples of PFIC1 and BRIC

Loci for two inherited liver diseases, benign recurrent intrahepatic cholestasis (BRIC) and progressive familial intrahepatic cholestasis type 1 (PFIC1), have previously been mapped to 18q21 by a search for shared haplotypes in patients in two isolated populations. This paper describes the use of further haplotype evaluation with a larger sample of patients for both disorders, drawn from several different populations. Our assessment places both loci in the same interval of less than 1 cM and has led to the discovery of the PFIC1/BRIC gene, FIC1; this discovery permits retrospective examination of the general utility of haplotype evaluation and highlights possible caveats regarding this method of genetic mapping. Received: 21 September 1998 / Accepted: 29 December 1998