African dust clouds are associated with increased paediatric asthma accident and emergency admissions on the Caribbean island of Trinidad

A retrospective ecological study of paediatric asthma patients who attended the Accident and Emergency (A&E) department of the Paediatric Priority Care Facility at the Eric Williams Medical Sciences Complex in relation to Saharan dust visibility and other climatic variables for the period 23 May 2001 to 13 May 2002 was undertaken to determine if there is an association between paediatric A&E asthma visits and Saharan dust cloud cover. A Poisson regression model was used to determine the statistical relationship between acute paediatric asthma A&E visits and Saharan dust cover with and without other variables such as climatic parameters and month. During the study period, there were 2,655 A&E visits for acute asthma. There was an association between increased paediatric asthma admissions and increased Saharan dust cover. The best fitting model estimated that in one month, such as June, a deterioration of visibility due to increased Saharan dust cover from no dust (visibility =16 km) to very dusty (visibility =7 km) would increase a daily admission rate of 7.8 patients to 9.25 when climate variables such as barometric pressure and humidity were kept constant.     

Viability and activity in readily culturable bacteria: a review and discussion of the practical issues

In microbiology the terms viability and culturability are often equated. However, in recent years the apparently self-contradictory expression viable-but-nonculturable (VBNC) has been applied to cells with various and often poorly defined physiological attributes but which, nonetheless, could not be cultured by methods normally appropriate to the organism concerned. These attributes include apparent cell integrity, the possession of some form of measurable cellular activity and the apparent capacity to regain culturability. We review the evidence relating to putative VBNC cells and stress our view that most of the reports claiming a return to culturability have failed to exclude the regrowth of a limited number of cells which had never lost culturability. We argue that failure to differentiate clearly between use of the terms viability and culturability in an operational versus a conceptual sense is fuelling the current debate, and conclude with a number of proposals that are designed to help clarify the major issues involved. In particular, we suggest an alternative operational terminology that replaces VBNC with expressions that are internally consistent.     

Inheritance and linkage of isozyme loci in almond

The segregation of seven isozyme marker genes was investigated using eight controlled crosses in almond. The cultivar Nonpareil was the maternal parent in all crosses. Pollination was achieved using eight different cultivars, and a total of 3200 individual kernels were assessed. For each isozyme the goodness-of-fit test was used to test for departure from the expected frequencies assuming Mendelian inheritance. Given a higher than expected number of significant results for individual isozymes, independent segregation between pairs of isozymes was tested using the chi-square statistic on the resulting two-way contingency tables. In all crosses a highly significant association (P value< 0.001) was observed between (1) the AAT- 1 and IDH isozymes loci and (2) the LAP-1 and PGM-2 isozymes loci, which leads to the conclusion that the respective isozyme pairs are linked.In addition, a significant association (P value < 0.001) was observed between LAP-1 and GPI-2 when the pollen sources were Fritz, Mission, or Price, but this could not be tested for the remaining five pollen sources, Carmel, Grant, Keane, Ne plus Ultra, Peerless, because they are homozygous at these loci. If LAP-1 is linked with GPI-2 and PGM-2, it might be expected that we should find evidence of linkage between GPI-2 and PGM-2. The lack of a significant association between these two isozymes suggests that LAP-1 is located centrally on the chromosome. These three pairs of linked loci are the first to be reported in almond.     

Under the Weather: Legionellosis and Meteorological Factors

The incidence of legionellosis, caused by the bacteria Legionella which are commonly found in the environment, has been increasing in New Jersey (NJ) over the last decade. The majority of cases are sporadic with no known source of exposure. Meteorological factors may be associated with increases in legionellosis. Time series and case-crossover study designs were used to evaluate associations of legionellosis and meteorological factors (temperature (daily minimum, maximum, and mean), precipitation, dew point, relative humidity, sea level pressure, wind speed (daily maximum and mean), gust, and visibility). Time series analyses of multi-factor models indicated increases in monthly relative humidity and precipitation were positively associated with monthly legionellosis rate, while maximum temperature and visibility were inversely associated. Case-crossover analyses of multi-factor models indicated increases in relative humidity occurring likely before incubation period was positively associated, while sea level pressure and visibility, also likely preceding incubation period, were inversely associated. It is possible that meteorological factors, such as wet, humid weather with low barometric pressure, allow proliferation of Legionella in natural environments, increasing the rate of legionellosis.     

The Association between Cold Spells and Pediatric Outpatient Visits for Asthma in Shanghai, China

Background

Asthma is a serious global health problem. However, few studies have investigated the relationship between cold spells and pediatric outpatient visits for asthma.

Objective

To examine the association between cold spells and pediatric outpatient visits for asthma in Shanghai, China.

Methods

We collected daily data on pediatric outpatient visits for asthma, mean temperature, relative humidity, and ozone from Shanghai between 1 January 2007 and 31 December 2009. We defined cold spells as four or more consecutive days with temperature below the 5^th percentile of temperature during 2007–2009. We used a Poisson regression model to examine the impact of temperature on pediatric outpatient visits for asthma in cold seasons during 2007 and 2009. We examined the effect of cold spells on asthma compared with non-cold spell days.

Results

There was a significant relationship between cold temperatures and pediatric outpatient visits for asthma. The cold effects on children''s asthma were observed at different lags. The lower the temperatures, the higher the risk for asthma attacks among children.

Conclusion

Cold temperatures, particularly cold spells, significantly increase the risk of pediatric outpatient visits for asthma. The findings suggest that asthma children need to be better protected from cold effects in winter.     

Evaluation of thermal discomfort in Athens territory and its effect on the daily number of recorded patients at hospitals’ emergency rooms

Previous research has shown that temperature and humidity affect human health. However, only a few studies have examined the association of a biometeorological index, which combines several meteorological parameters and human physiology, with health outcomes. The aim of the present study is to assess the thermal discomfort in Athens city by using the Predicted Mean Vote (PMV) as well as to examine its association with the number of patients recorded at the emergency rooms of four main hospitals. Patients were selected based on their diagnosis during the summer season (June–August) from 1998 to 2004. Data included hourly values of meteorological parameters and daily numbers of patients who visited the emergency units of cardiology departments. Poisson regression models were applied using generalized estimating equations. A strong negative correlation between mean and maximum daily values of PMV and the number of emergency department visits was identified. More studies are needed to explore the association of this biometeorological index with health outcomes in other regions.     

Microelectronic detection of activity level and magnetic orientation of yellow European eel, <Emphasis Type="Italic">Anguilla anguilla</Emphasis> L., in a pond

Synopsis We studied the circadian and monthly activity, the distribution patterns, and orientation to the earths magnetic field, of yellow (non-migratory) female eels in a freshwater pond by means of microchips injected into their muscles. Detectors for microchips mounted in tubes were placed in the pond to detect if eels oriented themselves with respect to earths magnetic field. Based on the frequency of tube visits (search for shelter), the data indicated that the presence of eel in the tubes decreases gradually during the study period. We saw more activity during the night in the first months. There was a seasonal component in the orientation mechanism, with a significantly lower preference component in the summer compared to the fall. A preference for tubes oriented in a south-southwest direction (the direction of the Sargasso Sea) in fall suggests an orientation to the earths magnetic field.     

A new integrated genetic linkage map of the soybean

A total of 391 simple sequence repeat (SSR) markers designed from genomic DNA libraries, 24 derived from existing GenBank genes or ESTs, and five derived from bacterial artificial chromosome (BAC) end sequences were developed. In contrast to SSRs derived from EST sequences, those derived from genomic libraries were a superior source of polymorphic markers, given that the mean number of tandem repeats in the former was significantly less than that of the latter (P<0.01). The 420 newly developed SSRs were mapped in one or more of five soybean mapping populations: Minsoy × Noir 1, Minsoy × Archer, Archer × Noir 1, Clark × Harosoy, and A81-356022 × PI468916. The JoinMap software package was used to combine the five maps into an integrated genetic map spanning 2,523.6 cM of Kosambi map distance across 20 linkage groups that contained 1,849 markers, including 1,015 SSRs, 709 RFLPs, 73 RAPDs, 24 classical traits, six AFLPs, ten isozymes, and 12 others. The number of new SSR markers added to each linkage group ranged from 12 to 29. In the integrated map, the ratio of SSR marker number to linkage group map distance did not differ among 18 of the 20 linkage groups; however, the SSRs were not uniformly spaced over a linkage group, clusters of SSRs with very limited recombination were frequently present. These clusters of SSRs may be indicative of gene-rich regions of soybean, as has been suggested by a number of recent studies, indicating the significant association of genes and SSRs. Development of SSR markers from map-referenced BAC clones was a very effective means of targeting markers to marker-scarce positions in the genome.Electronic Supplementary Material Supplementary material is available in the online version of this article at Communicated by C. Möllers     

Cytogenetic analysis of structural rearrangements in three varieties of common wheat,Triticum aestivum

Summary The winter wheat varieties Starke and Cappelle Desprez and the spring wheat Chinese Spring were analysed for structural chromosome rearrangements that resulted in the formation of multivalents in F₁ hybrids. The analyses were carried out using hybrids involving euploids, monosomic and ditelosomic stocks, and double-monotelodisomic constructs. The study confirmed that Cappelle Desprez differs from Chinese Spring in a reciprocal translocation between chromosomes 5B and 7B (Riley et al. 1967); a translocation involving chromosomes 3B and 3D could not be verified. Furthermore, the analysis showed that Starke differs from Chinese Spring in a reciprocal translocation between chromosomes 7A and 7D. Both translocations have a coefficient of multivalent realisation of about 0.84. Further multivalents in euploid Starke, in euploid and some aneuploid stocks of Cappelle Desprez, and in euploid as well as various types of aneuploid hybrids between all three varieties could nearly all be explained hypothesizing that chromosome 2B of both Starke and Cappelle Desprez is a duplication-deficiency chromosome. In the hypothesis a part of the long arm of 2B is missing and replaced by a duplicated part of the long arm of chromosome 2D. The multivalents of this rearrangement showed an average coefficient of realisation of about 0.09.Sven Ellerström died in December 1985     

On the distinction between niche and competitive ability: Implications for coexistence theory

The meaning of niche and competitive ability have long been surrounded by controversy. The reason for this stems from the obscure relationship that exists between these terms. This extends from the views of Darwin through Eltonian tradition to current views in which the meaning of competitive ability is implicitly infused into the paradigm of niche. Distinct operational definitions for niche and competitive ability are therefore established with special reference to plants. It is proposed that potential niche refer explicitly to a theoretical hyperspace of places where a species would leave descendents if all biotic interactions were precluded, and that competitive ability refer to the relative capacity to leave descendents in a particular place in the face of restrictions imposed by competitive interaction. This leads to a qualitative comprehensive theory for coexistence which may be extended to any type of biotic interaction. Niche and competitive ability are both determined by the biological attributes of a species and may be independently adjusted in a population by natural selection in contexts of competition. Species coexistence in nature may therefore be a consequence of alternative evolutionary mechanisms which may operate to various degrees in concert: (1) natural selection leading to niche differentiation; (2) an ongoing process of reciprocal selection (coevolution) which maintains an approximate balance in relative competitive abilities for contested resources.     

Immunofluorescence localization of the epidermolytic toxin target in mouse epidermal cells and tissue

Summary An epidermolytic toxin target was observed in keratohyalin granules of sectioned epidermis by a direct fluorescence procedure using FTC-toxin, but not by an indirect procedure using sequential reaction with toxin, anti-toxin and FTC-secondary antibody. The investigation of the two procedures was extended to keratinocytes. A dispase digestion procedure yielded three fractions which corresponded to basal, spinous and granular cells according to biochemical and morphological criteria. It was shown that the direct and indirect procedures both detected the toxin target in the keratohyalin granules of granular cells, but that the indirect procedure was very insensitive. In control experiments, the profilaggrin of keratohyalin granules was detected readily in cells by a direct procedure using FTC-antiprofilaggrin but only weakly by an indirect double antibody procedure. Insensitivity to indirect procedures thus appears to be a particular property of the keratohyalin granule site. It was shown that the toxin target was readily accessible in permeable (trypsin-isolated) granular cells but inaccessible in impermeable (dispase-isolated) cells.     

Molecular mapping of a new gene Rrs4 CI 11549 for resistance to barley scald (Rhynchosporium secalis)

Doubled haploid (DH) progeny from a cross between the scald susceptible barley (Hordeum vulgare L.) cultivar Ingrid and the resistant accession CI 11549 (Nigrinudum) was evaluated for resistance in the pathogen Rhynchosporium secalis (Oudem) J.J. Davis. Two linked and incompletely dominant loci confer resistance CI 11549 against isolate 4004. One is an allele at the complex Rrs1 locus on chromosome 3H close to the centromere; the other is located 22 cM distally on the long arm. The latter locus is designated Rrs4. In BC₃-lines into Ingrid from CI 2222 (another Nigrinudum) resistance seems governed by one locus close to the telomeric region of chromosome 7H, probably allelic to Rrs2. In neither case did we find any trace of the recessive gene rh8 reported to be present in Nigrinudum. Various resistance donors of Ethiopian origin designated as Nigrinudum, Jet or Abyssinian were identical to a great extent with respect to markers, but differed in resistance to different isolates of scald or in barley yellow dwarf virus (BYDV) resistance. The implications for their use as differentials in scald tests and screening of germplasm collections are discussed.     

‘Free’ iron, as detected by electron paramagnetic resonance spectroscopy, increases unequally in different tissues during dietary iron overload in the rat

Free iron concentration, as determined by electron paramagnetic resonance (EPR) spectroscopy, and lipid peroxidation (LPO), as determined by thiobarbituric acid test, were assessed in the lung, heart, liver, spleen, brain and kidney of rats subjected to experimental iron overload. Two tests, Desferal- and NO-available iron, were used to measure free iron and gave comparable results. The most pronounced accumulation of free iron was observed in liver, kidney and spleen. Differences between control and iron loaded animals increased during the initial 90 days of treatment. Between 90 and 180 days free iron concentration reached a steady state level, or even decreased, as in the case of liver. Lipid peroxidation level, measured in the organs of both treated and matched controls, did not give any significant difference during the initial 90 days of treatment. A significant augmentation was observed in liver, kidney, spleen and heart at 180 days. The results of the present research show that, under conditions of moderate siderosis, the occurrence of LPO is partially related to the level of free iron.     

Sublittoral macrozoobenthic assemblages in the enclosed sediment-polluted Rhine-Meuse Delta; their relationship to environmental conditions

Composition, densities and biomass of sublittoral macrozoobenthos were investigated at 14 sites in the enclosed Rhine-Meuse Delta. The aim was to identify the main macrozoobenthic assemblages and to establish their relationship with environmental conditions, including sediment pollution. Most sites were dominated by the tubificidsLimnodrilus hoffmeisteri andL. claparedeanus. Four zoobenthic assemblages could be identified. They are related to different geomorphological phases of a basin filling up with fluvial sediment causing a longitudinal sediment gradient. The Rhine river assemblage was found in the Nieuwe Merwede, filled up in the 1970's, the soft mud assemblage in the Hollands Diep at sites with high sedimentation rates; the basin silt assemblage in the Amer, Hollands Diep and Haringvliet, at sites with lower sedimentation rates, and the basin shoal assemblage at former flats with low sedimentation rates. CANOCO was used to relate the TWINSPAN indicator species to a selection of environmental parameters. Sediment pH, water content, sand fraction, total polycyclic aromatic hydrocarbons (PAH) and current velocity explained 44% of the variance of the average abundance of the indicator taxa per site. Sediment firmness, indicated by sediment water content, and high ammonium concentrations probably were together responsible for the very low densities in the soft mud assemblage. Densities and biomasses in the other assemblages were low as well, except for theDreissena polymorpha habitat, where very high total zoobenthic biomass values (max. 55.8 g m^–2) were observed. It is argued that sediment contamination has a considerable impact on macrozoobenthic densities and species composition in all assemblages, the basin shoal assemblage excepted.     

Quantitative inheritance and barriers to crossability in Cicer arietinum L.

Summary Three different diallel crosses were studied in Cicer arietinum; two of size 6×6, one within each of the two botanical groups macrosperma and microsperma of the cultivated subspecies, and one of 9×9 involving lines covering most of the morphological variation of chickpea. Barriers to crossability present neither a botanical nor a geographical pattern, being probably a direct consequence of interactions between genotypes. The genetic systems of twelve quantitative characters were analysed. Full dominance in a negative sense (small values dominant) is shown by leaflet length, width and shape index, rachis length, leaflet density on the rachis and pod length. Full dominance in a positive sense is shown by seeds per pod. Overdominance (in a positive sense) is evident for pods, seeds and yield per plant. Weak reciprocal differences were manifested by pod length, and pods, seeds and yield per plant. The system controlling number of leaflets per leaf is not clear. Dominance of primitive over selected characters seems to be the rule. As far as the environmental effects have permitted the analysis, no differences in genetic systems were observed between botanical groups.     

Use of RFLP markers for the identification of alleles of the Pm3 locus conferring powdery mildew resistance in wheat (Triticum aestivum L.)

The objective of this study was to identify molecular markers linked to genes for resistance to powdery mildew (Pm) in wheat using a series of Chancellor near-isogenic-lines (NILs), each having one powdery mildew resistance gene. A total of 210 probes were screened for their ability to detect polymorphism between the NILs and the recurrent parent. One of these restriction fragment length polymorphism (RFLP) markers (Xwhs179) revealed polymorphism not only between the NILs for the Pm3 locus, but also among NILs possessing different alleles of the Pm3 locus. The location of the marker Xwhs179 was confirmed to be on homoeologous chromosome group 1 with the help of nullitetrasomic wheat lines. The linkage relationship between this probe and the Pm3 locus was estimated with double haploid lines derived from a cross between wheat cvs Club and Chul (Pm3b). The genetic distance was determined to be 3.3±1.9 cM.     

Measurement of frequency-dependent sexual activity in Drosophila Melanogaster

In experiments on sexual competition in Drosophila melanogaster, the course of mating succes with time is represented by a sigmoid curve. By logarithmic transformation such curves are changed into straight lines that can be compared by covariance analysis. This method allows discrimination of the behaviour of the two types in competition, and allows us to follow it in the course of time. From a sexual competition experiment between the wild type Canton S and the mutant white-ebony we conclude that sexual activity of males and females of both types is generally frequency dependent, with evidence of rare-female advantage as well as rare-male advantage.     

Ecological theories and Dutch nature conservation

This paper aims to achieve insight into various ecological theories in the Netherlands which have different, and sometimes opposing, views on the conservation of nature. Interviews, publications and archival research brought to light four separate theories: vitalistic/holistic, dynamic, cybernetic and chaos. Diversity is reached through stability according to vitalistic/holistic and cybernetic theories, but through change and instablility according to the dynamic and chaos theories. These two groups are working apart, and continue to have their own ideas. Prediction of the future is only possible with the vitalistic/holistic and cybernetic theories. Ecologists who adhere to these theories feel responsible and able in different ways to change ecological nature towards desirable end goals. The other two theories, dynamic and chaos, appear to be less activist.     

6′-Mercaptoguanosine-resistance is related with purF gene encoding 5′-phosphoribosyl-1′-pyrophosphate amidotransferase in inosine-5′-monophosphate overproducing Brevibacterium ammoniagenes

From the gene library constructed with the chromosomal DNA of 6-mercaptoguanosine (MGS)-resistant strain Brevibacterium ammoniagenes IPR-1, a DNA fragment which conferred MGS-resistance to the wild-type strain B. ammoniagenes ATCC6872 was cloned. The purF gene encoding 5-phosphoribosyl-1-pyrophosphate amidotransferase was identified from this fragment and its nucleotide sequence was determined. Wild type purF gene was also cloned by polymerase chain reaction using chromosomal DNA of ATCC6872 as the template and its sequence was determined. Two nucleotides, 583 A and 1065 A, of MGS-resistant purF gene had been changed from 583 G and 1065 G by mutagenesis, respectively. Both changes at position 583 and 1065 were proved to be responsible for MGS-resistance by site-directed mutagenesis.     

Mycoflora and aflatoxins in a West African corn-groundnut based convenience food

A total of 14 fungal species, mostly toxigenic, were isolated from 50 samples of donkwa snack obtained from 16 producers. All of the isolates recorded substantial growth, though at varying rates, on the 2% snack agar provided. They also induced a reduction in the oil and an increase in free fatty acids of the substrate suggesting their participatory roles in deterioration. Most of the snack samples analysed contained initial amounts of aflatoxins above the safe permissible level (30 ppb). The initial toxin levels increased substantially with storage time under 79.5, 89.5 and 100% ambient relative humidities but increased only slightly when samples were kept at 71% relative humidity. Almost constant toxin levels were recorded throughout the study period under 51% relative humidity. Accumulation of aflatoxin B₁ in samples was most enhanced at 89.5% relative humidity. Comparatively, greater amounts of aflatoxin B₁ accumulated under all conditions than the amounts recorded for aflatoxin G₁.