Influence of Nitrogen Supply on Uptake and Translocation of Strontium and Calcium in Wheat Seedlings

Supplying nitrate to N-depleted wheat seedlings (Triticum vulgare cv. Knox) stimulated the uptake and translocation of both ⁸³Sr and ⁴⁵Ca. Since the increase in ⁴⁵Ca accumulation was greater, the ⁸⁵Sr/⁴⁵Ca ratio in the plant tissue was decreased. Nitrate had relatively little influence on the amount of the divalent cations and ⁸⁵Sr/⁴⁵Ca ratio in the exchangeable fraction on the root surfaces, whereas it greatly increased the uptake into root tissue and translocation to shoots. The increase in percent transported to shoots occurred largely in the period of most rapid nitrate uptake. A split root study indicated that nitrate was ineffective when it was supplied to a different portion of the root system than that exposed to ⁸⁵Sr and ⁴⁵Ca. Nevertheless, ammonium and urea also increased the translocation of the two cations, indicating that the effects of nitrate could not entirely be ascribed to a direct effect of the nitrate anion.     

Assessing the diagnostic validity of a structured psychiatric interview in a first-admission hospital sample

The use of structured psychiatric interviews performed by non-clinicians is frequent for research purposes and is becoming increasingly common in clini-cal practice. The validity of such interviews has rarely been evaluated empirically. In this study of a sample of 100 diagnostically heterogeneous, first-admitted inpatients, the results of an assessment with the Structured Clinical Interview for DSM-IV (SCID), yielding a DSM-IV diagnosis and performed by a trained non-clinician, were compared with a consensus lifetime best diagnostic estimate (DSM-IV) by two experienced research clinicians, based on multiple sources of information, which included videotaped comprehensive semi-structured narrative interviews. The overall kappa agreement was 0.18. The sensitivity and specificity for the diagnosis of schizophrenia by SCID were 19% and 100%, respectively. It is concluded that structured interviews performed by non-clinicians are not recommendable for clinical work and should only be used in research with certain precautions. It is suggested that a revival of systematic theoretical and practical training in psychopathology is an obvious way forward in order to improve the validity and therapeutic utility of psychiatric diagnosis.     

Pre-dispersal seed losses to insects in species of Leptospermum (Myrtaceae)

Pre-dispersal seed losses to insects in species of Leptospermum at Wilson's Promontory in south-eastern Australia varied markedly between species, seasons, sites and individuals. The proportion of fruits attacked by insects averaged 11% (range 3–37%) in populations of Leptospermum juniperinum, 23% (6–95%) in Leptospermum myrsinoides, 23% (0–47%) in Leptospermum laevigatum, and 28% (8–45%) in Leptospermum lanigerum. The proportion of seeds lost in attacked fruits also varied widely. Differences between species varied markedly from year to year, but differences between sites were relatively constant. Fruit production by L. myrsinoides was unusually low at most sites during 1984; in each case this coincided with unusually high rates of insect attack, suggesting that predator satiation operates during normal seasons.     

Matching thirty years of ecosystem monitoring with a high resolution microfossil record

1. Monitoring of the ecosystem of Lake Mývatn, Iceland, since 1975 has revealed extreme fluctuations in important food web components, such as chironomids and cladocerans, with amplitudes of several orders of magnitude and a period of 5–8 years. This study uses sediment cores from the lake to examine if the food web fluctuations appear in the microfossil record of the sediment. 2. Dating was achieved by means of a combination of ¹³⁷Cs and volcanic tephra and was fine‐tuned by wiggle‐matching of chironomid microfossil and monitoring data. 3. Cladocera exuviae and chironomid egg capsules in the uppermost 34 cm of sediment were compared with the monitoring record that consisted of 30 years of window trap catches of flying chironomids and a 16‐year record of chydorid Cladocera caught in activity traps. 4. The observed chironomid and cladoceran population fluctuations were reflected in the sediment record of chironomid eggs and of the exuviae of three of seven cladocerans: Alonella nana, Alona rectangula and Eurycercus lamellatus, which also had the most extreme fluctuations in the monitoring data (3–4 orders of magnitude). Chydorus sphaericus, and to some extent Alona quadrangularis and Acroperus harpae, showed regular fluctuations in the core that the monitoring did not reveal. Density of subfossil chironomid eggs correlated positively with that of larval head capsules but not with other microfossils. 5. This study shows a reasonably good correspondence between the fossil records of chironomids and cladocerans on the one hand and biomonitoring data on the other. The results pave the way for an extension of the food web history to much earlier time intervals of the ecosystem, allowing the study of long‐term variation in the food web dynamics, including the impact of climatic variation and other external forcing. The results also indicate the usefulness of chironomid egg capsules in palaeolimnological studies.     

Canopy height and seed yield in winter linseed (Linum usitatissimum) can be influenced by proximity to pink canes

Changes to growth and development in a winter linseed crop were observed adjacent to pink canes used as markers in 1997. Notably, canopy height was increased in plants positioned up to 40 cm from the pink canes. In 1998 these effects were confirmed and further characterised in a replicated experiment: extension growth occurred approximately one week earlier and canopy height was increased by 14.5 cm in plants adjacent to pink canes. The number of seed capsules was 953 m^?2 in control plots and 2567 m^?2 in plots with pink canes. Seed yield, calculated from a 0.25 m² quadrat, was 12.4 g m² in control plots and 56.1 g m^?2 in plots with pink canes. The R:FR (red:far red) ratio of light reflected from canes was approximately 1.7 compared with approximate R:FR ratios of 1.4 in incident daylight and 0.2 in light reflected from a linseed canopy (assessed using a spectral analysis system). Possible mechanisms to explain the changes in crop performance are discussed.     

Cross‐species amplification of 105 Lolium perenne SSR loci in 23 species within the Poaceae

Amplification of 105 Lolium perenne SSR markers was studied in 23 grass species representing seven tribes from three subfamilies of Poaceae. Twelve of the SSR markers are published for the first time. Between 2% and 96% of the SSR markers could be amplified within a given species. A subset of eight SSR markers was evaluated for polymorphism across nine of the 23 grass species. Four to seven of the markers were polymorphic within each species, with an average detection of 2.4 alleles per species.     

Experimental disturbance by walkers affects behaviour and territory density of nesting Black-tailed Godwit Limosa limosa

In Europe, the number of areas supporting breeding Black-tailed Godwit Limosa limosa has halved over the last 30 years. Although the decline has been primarily attributed to habitat deterioration, human disturbance has also been implicated. We undertook a controlled experimental study at the Danish Special Protection Area (SPA) reserve at Tipperne, comparing bird behaviour and breeding densities from two baseline years with those in 3 years with two experimental levels of disturbance. Black-tailed Godwits flushed and showed mobbing behaviour significantly more often when disturbed. The duration of simultaneous flights by breeding pairs was greater when disturbed, leaving nests susceptible to predation. Behavioural observations suggested birds were highly sensitive to human disturbance and unlikely to habituate. Disturbance levels of seven walkers/day affected territory densities up to 500 m from routes taken by walkers, causing effective habitat loss to breeding Black-tailed Godwits. The species' sensitivity to disturbance may help explain why it has disappeared from many areas. Effective conservation of important breeding areas and maintenance of high densities of Black-tailed Godwit and other meadow birds necessitates control of public disturbance to breeding areas.