Repetitive flanking sequences (ReFS): novel molecular markers from microsatellite families

Although microsatellite markers have become exceedingly popular in molecular studies of wild organisms, their development in some taxonomic groups is challenging. This is partly because of repetitive flanking sequences, which lead to the simultaneous amplification of alleles from multiple loci. Until now, these microsatellite DNA families have been considered unsuitable for population genetics studies, but here we describe our development of these repetitive flanking sequences (ReFS) as novel molecular markers. We illustrate the utility of these markers by using them to address an outstanding taxonomic question in the moth genus Schrankia.     

Alternative explanations for rising dissolved organic carbon export from organic soils

Since 1988, there has been, on average, a 91% increase in dissolved organic carbon (DOC) concentrations of UK lakes and streams in the Acid Waters Monitoring Network (AWMN). Similar DOC increases have been observed in surface waters across much of Europe and North America. Much of the debate about the causes of rising DOC has, as in other studies relating to the carbon cycle, focused on factors related to climate change. Data from our peat‐core experiments support an influence of climate on DOC, notably an increase in production with temperature under aerobic, and to a lesser extent anaerobic, conditions. However, we argue that climatic factors may not be the dominant drivers of DOC change. DOC solubility is suppressed by high soil water acidity and ionic strength, both of which have decreased as a result of declining sulphur deposition since the 1980s, augmented during the 1990s in the United Kingdom by a cyclical decline in sea‐salt deposition. Our observational and experimental data demonstrate a clear, inverse and quantitatively important link between DOC and sulphate concentrations in soil solution. Statistical analysis of 11 AWMN lakes suggests that rising temperature, declining sulphur deposition and changing sea‐salt loading can account for the majority of the observed DOC trend. This combination of evidence points to the changing chemical composition of atmospheric deposition, particularly the substantial reduction in anthropogenic sulphur emissions during the last 20 years, as a key cause of rising DOC. The implications of rising DOC export for the carbon cycle will be very different if linked primarily to decreasing acid deposition, rather than to changes in climate, suggesting that these systems may be recovering rather than destabilising.     

Factors Controlling the Abundance and Size Distribution of the Phototrophic Ciliate Myrionecta rubra in Open Waters of the North Atlantic

ABSTRACT. Myrionecta rubra, a ubiquitous planktonic ciliate, has received much attention due to its wide distribution, occurrence as a red tide organism, and unusual cryptophyte endosymbiont. Although well studied in coastal waters, M. rubra is poorly examined in the open ocean. In the Irminger Basin, North Atlantic, the abundance of M. rubra was 0–5 cells/ml, which is low compared with that found in coastal areas. Distinct patchiness (100 km) was revealed by geostatistical analysis. Multiple regression indicated there was little relationship between M. rubra abundance and a number of environmental factors, with the exception of temperature and phytoplankton biomass, which influenced abundance in the spring. We also improve on studies that indicate distinct size classes of M. rubra; we statistically recognise four significantly distinct width classes (5–16, 12–23, 18–27, 21–33 μm), which decrease in abundance with increasing size. A multinomial logistic regression revealed the main variable correlated with this size distribution was ambient nitrate concentration. Finally, we propose a hypothesis for the distribution of sizes, involving nutrients, feeding, and dividing of the endosymbiont.     

Solute transport into healthy and powdery mildew-infected leaves of pea and uptake by powdery mildew mycelium

The transport of sugars and amino acids into the mycelium of Erysiphe pisi DC. was investigated using two different systems, intact leaf discs and mycelial suspensions. Of the sugars tested, glucose was preferentially taken up by both uninfected and mildew-infected leaf discs, whereas glutamine was taken up by both tissues at a higher rate than lysine or aspartic acid. Leaf discs from infected tissue had a greater uptake capacity than those from healthy tissue for both sugars and amino acids. The uptake of glucose was inhibited more markedly than that of sucrose and fructose by 10 μ m carbonyl cyanide m -chlorophenylhydrazone (CCCP), 1 m m N -ethylmaleimide (NEM), 1 m m diethyl pyrocarbonate (DEPC) and 1 m m phenylglyoxal, whereas 1 m m PCMBS ( p -chloro-mercuribenzenesulphonic acid) inhibited sucrose uptake to the greatest extent. Uptake of glutamine, lysine and aspartic acid was inhibited similarly by CCCP (80%), NEM (20%), DEPC (70%) and PCMBS (60%). Additionally, leaf discs were used to determine which solutes could be taken up from leaf tissue by the fungus. The uptake of sugars into the mycelium was greater than that of amino acids.
Suspensions of powdery mildew mycelium accumulated glucose at about three times the rate of sucrose or fructose, and the amino acid glutamine was taken up at three times the rate of lysine or aspartic acid. Spores separated from the suspension had a low uptake capacity.
When the reducing sugar concentration of leaf apoplastic fluid was estimated, leaves infected by powdery mildew had much higher amounts in the apoplast, whereas the activity of acid invertase also appeared to be higher in apoplastic fluids from infected leaves. When apoplastic fluid samples were run on SDS gels, an invertase antibody detected two bands in samples from infected tissues that were not found in the uninfected samples.     

Effect of past and present behavioural specialization on brain levels of biogenic amines in workers of the red wood ant Formica polyctena

Social insect workers usually participate first in intranidal tasks (i.e. act as nurses within the nest) and then switch to extranidal tasks and become foragers. However, foragers sometimes switch back again to brood care and become reverted nurses. Behavioural and physiological correlates of the transition nurse–forager (behavioural maturation) and forager–reverted nurse (behavioural reversion) are relatively well known in the honeybee, although they are less explored in ants. To understand better the role of biogenic amines in ant behavioural maturation and behavioural reversion, the levels of octopamine (OA), dopamine (DA) and serotonin (5‐HT) are examined in the brains of nurses, foragers and reverted nurses of the red wood ant Formica polyctena Först. (Hymenoptera: Formicidae). Brain OA levels and the ratios OA : DA and OA : 5‐HT are higher in nurses than in foragers and reverted nurses. Reverted nurses and foragers do not differ significantly with respect to brain biogenic amine levels and amine ratios. Biogenic amine levels in brains of workers of F. polyctena are thus maturation‐related rather than task‐related. This is one of the first studies of neurochemical correlates of ant behavioural maturation and the first attempt to identify neurobiological correlates of ant behavioural reversion. The data obtained provide further evidence that neurobiological processes underlying honeybee and ant behavioural maturation and behavioural reversion reveal important differences.     

Larval food affects oviposition preference,female fecundity and offspring survival in Yponomeuta evonymellus

1. Yponomeuta evonymellus is a monophagous moth that feeds on Prunus padus which is native to Europe. In recent years, larval feeding and egg clusters have also been observed on non‐native Prunus serotina plants; however, survival of larvae on this new host is very low. 2. The objective of the present study was to determine how the feeding of larvae on each of the two host plants impacts oviposition, offspring survival and fecundity in Y. evonymellus. Our hypothesis was that, under controlled conditions, females will lay eggs on the host on which they fed as larvae. We also hypothesised that the lower survival of young larvae feeding on P. serotina was due to the smaller buds and leaves present in this species, relative to those of P. padus. 3. A dual‐choice experiment conducted under laboratory conditions demonstrated that females preferentially chose to oviposit on the plant species on which they fed as larvae. In the experiment, potential fecundity and offspring survival were significantly higher on P. padus than on P. serotina. The reduced performance of Y. evonymellus on P. serotina was correlated with a smaller bud mass and volume, lower leaf mass and surface area, and difficulty in constructing a protective tent against unfavourable weather conditions. 4. In summary, the identity of the host plant species during larval feeding determines adult oviposition preference for that host species. The survival of larvae on P. serotina growing in the nature is low, but for phenology‐related reasons.     

Haemoglobin concentration and body condition of nestling Great Tits Parus major : a comparison of first and second broods in two contrasting seasons

The physiological condition of nestling altricial birds depends on the quantity and quality of food delivered to them by parents. One indicator of the condition of Great Tit Parus major nestlings is the haemoglobin concentration in their blood. The present study demonstrates the influence of weather conditions (temperature and rainfall) on nestling haemoglobin concentrations during two consecutive breeding seasons in two different habitat types (parkland vs. woodland) in the city of Łódź in Central Poland. This influence probably results from the effects of weather on the trophic base of the Tits. Dry, hot weather strongly affected bush and herbal foliage later in the breeding season (mid-June to mid-July) in 2006, presumably by interfering with the development of herbivorous arthropod populations. This in turn caused food shortages for second broods of Great Tits, which resulted in nestlings having low haemoglobin levels. In the following year, temperature was on average lower, and rainfall was regular but not very heavy. These conditions enabled the development of arthropod assemblages, and the trophic base for birds was much richer. Haemoglobin concentrations in the blood of nestlings from second broods were significantly higher than those of first broods and, unexpectedly, second-brood nestlings in 2007 were on average in better physiological state than first-brood nestlings in 2006 in both habitats. The relationship between haemoglobin concentration, brood category and year was very similar to that for nestling body mass. However, it was independent of both body mass and brood size. In some years and under certain conditions, second broods can be more successful than first broods.     

Ultrastructural Organization of Leaves of Transgenic Tobacco Overexpressing Histone H1 from Arabidopsis thaliana

We investigated the anatomical and ultrastructural featuresof transgenic tobacco plants that overexpressed a gene of histoneH1 from Arabidopsis thaliana. The overexpression of the heterologousgene resulted in more than a 2.5-fold increase over the physiologicallevel of the histone H1:DNA ratio in chromatin. H1-overexpressingplants had a distinct mutant phenotype characterized by dwarfappearance and severely hampered flowering. These changes wereaccompanied by extensive and unusual heterochromatinizationof nuclei occurring in all leaf parenchymal cells but not inleaf epidermal cells. The observed anomalies in the growth rateand size of the cells and in nuclei/chloroplast proportionsin histone H1-overexpressing plants suggest that the H1:DNAratio can influence some specialized cellular functions involvingthe cytoskeleton, and nuclear/organellar interactions whichare of importance for the normal development of a plant. Copyright1999 Annals of Botany Company Transgenic tobacco plant, histone H1 overexpression, heterochromatinization.