A chamber for the simulation of radiation freezing of plants

Frost injury to plants can occur following episodic radiation frosts. In the UK this is particularly important to spring sown crops such as potatoes. Most laboratory based frost studies simulate freezing using either conductive or convective freezing chambers. Such frost tests do not simulate overnight freezing events adequately. A freezing chamber based on radiative cooling is described which mimics overnight radiative freezing. The chamber is rectangular in design (1 m × lm × 2 m high) with a radiative cooling plate at the top of the chamber cooled to -40°C to -45°C using HFC coolants, which acts as a cold black body. The sides of the chamber are also cooled to variable temperatures down to -5°C in order to prevent the chamber walls radiating to the plant material during testing. Using thermocouples to measure air temperature and plant temperature the chamber has been characterised to simulate the radiative cooling conditions found in the UK during autumn and spring. Exotherm detection upon plant freezing is simplified by virtue of the reduction in temperature fluctuation normally experienced at the plant surface during natural freezing. Radiation frosts and subsequent frost damage to potatoes have been recorded in the temperature range -4°C to –5°C. The equipment is recommended for studies of frost damage to plants normally caused by episodic radiation frost events.     

Seasonal pattern in age, sex and body condition of Barn Owls Tyto alba killed on motorways

The Barn Owl Tyto alba was the most common owl killed on motorways in northeastern France. The possible causes of this mortality and the age, sex and body condition of the road-killed birds in 1991–1994 have been investigated. The number of birds killed on roads was highest in the period from early autumn to late winter, i.e. during the non-breeding period, and showed a pattern similar to that of the temporal difference between sunset, which varies with day length, and peak of traffic, the occurrence of which is constant throughout the year. An autumnal mortality peak, concomitant with the post-fledging dispersal, was mainly of immature birds, especially females. A second mortality peak in late winter was composed mainly of mature birds, with an equal proportion of males and females. From autumn to winter, there was no significant change in body mass in the different age and sex categories of birds killed on roads, except for mature males which had a significantly lower body mass in winter. From early autumn to late winter, the mean body mass of immature owls killed on motorways did not differ significantly from that of captive immatures fed ad libitum. This suggests that the immature birds were in good body condition. In contrast, the body mass of road-killed mature females was significantly lower than that of captive mature females over the same time periods. In mature males in late winter, a drop in body mass in both road-killed and captive birds suggests an endogenous seasonal phenomenon. Except for mature females, Barn Owls killed on roads in 1991–1994 were in good body condition. This does not support the idea that only birds in poor body condition were killed. We conclude that the mortality of Barn Owls on motorways in autumn and winter was probably related to the concomitance between the peak of traffic and the onset of hunting activity and the large number and dispersal of immature individuals during the same period.     

Temporal persistence and spatial distribution of an American inoculant strain of the ectomycorrhizal basidiomycete Laccaria bicolor in a French forest plantation

Selected strains of ectomycorrhizal fungi, such as the basidiomycete Laccaria bicolor , are currently being used as inoculants in nurseries to improve growth of forest trees after outplanting. Information is needed on the survival of these introduced strains in forests and their impact on indigenous biodiversity. Dissemination and persistence of an American strain, L. bicolor S238N, were studied 10 years after outplanting in a Douglas fir plantation located at Saint-Brisson (Morvan, France). About 430 Laccaria spp. sporophores were collected over 3 years. Inheritance of nuclear ribosomal DNA, as well as RAPD markers, was characterized in L. bicolor S238N, using a haploid progeny set of 91 monokaryons. More than 50 markers were identified (19 heterozygous and 33 homozygous or cytoplasmic markers), which unambiguously confirmed that the introduced strain was still present in the inoculated plots. Neither selfing ( P < 0.0008) nor introgression with indigenous strains was detected although in vitro interfertility between the American strain and indigenous L. bicolor was identified. No ingress of the introduced genet into adjacent uninoculated plots colonized by various local Laccaria genets was detected. It is proposed that the spatial distributions identified have developed through mycelial propagation of the introduced strain and intraspecific competition with native genets. Although longer-term data is still lacking, the stability of the inoculant strain and the limited disturbance to indigenous populations described support large-scale nursery production of this host-fungal combination.     

Projecting climate change impacts on species distributions in megadiverse South African Cape and Southwest Australian Floristic Regions: Opportunities and challenges

Increasing evidence shows that anthropogenic climate change is affecting biodiversity. Reducing or stabilizing greenhouse gas emissions may slow global warming, but past emissions will continue to contribute to further unavoidable warming for more than a century. With obvious signs of difficulties in achieving effective mitigation worldwide in the short term at least, sound scientific predictions of future impacts on biodiversity will be required to guide conservation planning and adaptation. This is especially true in Mediterranean type ecosystems that are projected to be among the most significantly affected by anthropogenic climate change, and show the highest levels of confidence in rainfall projections. Multiple methods are available for projecting the consequences of climate change on the main unit of interest – the species – with each method having strengths and weaknesses. Species distribution models (SDMs) are increasingly applied for forecasting climate change impacts on species geographic ranges. Aggregation of models for different species allows inferences of impacts on biodiversity, though excluding the effects of species interactions. The modelling approach is based on several further assumptions and projections and should be treated cautiously. In the absence of comparable approaches that address large numbers of species, SDMs remain valuable in estimating the vulnerability of species. In this review we discuss the application of SDMs in predicting the impacts of climate change on biodiversity with special reference to the species‐rich South West Australian Floristic Region and South African Cape Floristic Region. We discuss the advantages and challenges in applying SDMs in biodiverse regions with high levels of endemicity, and how a similar biogeographical history in both regions may assist us in understanding their vulnerability to climate change. We suggest how the process of predicting the impacts of climate change on biodiversity with SDMs can be improved and emphasize the role of field monitoring and experiments in validating the predictions of SDMs.     

Experiences with reducing point sources of phosphorus to lakes

Experiences over the last 25 years have demonstrated that eutrophication can be reversed, and that phosphorus is most often the nutrient through which control should be exerted.The reduction of the external load of phosphorus to a eutrophic lake is a necessary condition for lake restoration, but may not in itself be sufficient. Three main response patterns to a reduction in external load are identified. These include reduction in lake phosphorus that leads to sufficient reduction in chlorophyll to change the trophic category, to make the lakes less eutrophic or have small or no effect. The factors that determine the actual response are discussed.It is clear that interventions to restore eutrophic lakes have not always given the results expected. Limnological studies are necessary for well-grounded predictions.     

Characterization and overproduction of the Escherichia coli appA encoded bifunctional enzyme that exhibits both phytase and acid phosphatase activities

The appA gene that was previously shown to code for an acid phosphatase instead codes for a bifunctional enzyme exhibiting both acid phosphatase and phytase activities. The purified enzyme with a molecular mass of 44,708 Da was further separated by chromatofocusing into two isoforms of identical size with isoelectric points of 6.5 and 6.3. The isoforms had identical pH optima of 4.5 and were stable at pH values from 2 to 10. The temperature optimum for both phytase isoforms was 60 degrees C. When heated at different pH values the enzyme showed the greatest thermal resistance at pH 3. The pH 6.5 isoform exhibited K(m) and Vmax values of 0.79 mM and 3165 U.mg-1 of protein for phytase activity and 5.5 mM and 712 U.mg-1 of protein for acid phosphatase, respectively. The pH 6.3 isoform exhibited slightly lower K(m) and Vmax values. The enzyme exhibited similar properties to the phytase purified by Greiner et al. (1993), except the specific activity of the enzyme was at least 3.5-fold less than that previously reported, and the N-terminal amino acid sequence was different. The Bradford assay, which was used by Greiner et al. (1993) for determination of enzyme concentration was, in our hands, underestimating protein concentration by a factor of 14. Phytase production using the T7 polymerase expression system was enhanced by selection of a mutant able to grow in a chemically defined medium with lactose as the carbon source and inducer. Using this strain in fed-batch fermentation, phytase production was increased to over 600 U.mL-1. The properties of the phytase including the low pH optimum, protease resistance, and high activity, demonstrates that the enzyme is a good candidate for industrial production as a feed enzyme.     

Hypomania: a transcultural perspective

This study examined the transcultural robustness of a screening instrument for hypomania, the Hypomania Checklist-32, first revised version (HCL-32 R1). It was carried out in 2606 patients from twelve countries in five geographic regions (Northern, Southern and Eastern Europe, South America and East Asia). In addition, GAMIAN Europe contributed data from its members. Exploratory and confirmatory factor analyses were used to examine the transregional stability of the measurement properties of the HCL-32 R1, including the influence of sex and age as covariates. Across cultures, a two-factor structure was confirmed: the first factor (F1) reflected the more positive aspects of hypomania (being more active, elated, self-confident, and cogni-tively enhanced); the second factor (F2) reflected the more negative aspects (being irritable, impulsive, careless, more substance use). The measurement properties of the HCL-32 R1 were largely invariant across cultures. Only few items showed transcultural differences in their relation to hypomania as measured by the test. F2 was higher among men and in more severe manic syndromes; F1 was highest in North and East Europe and lowest in South America. The scores decreased slightly with age. The frequency of the 32 items showed remarkable similarities across geographic areas, with two excep-tions: South Europeans had lower symptom frequencies in general and East Europeans higher rates of substance use. These findings support the interna-tional applicability of the HCL-32 R1 as a screening instrument for hypomania.     

Cellulolytic Activity of Clostridium acetobutylicum

Clostridium acetobutylicum NRRL B527 and ATCC 824 exhibited extracellular and cell-bound endoglucanase and cellobiase activities during growth in a chemically defined medium with cellobiose as the sole source of carbohydrate. For both strains, the endoglucanase was found to be mainly extracellular (70 to 90%) during growth in continuous or batch cultures with the pH maintained at 5.2, whereas the cellobiase was mainly cell associated (60 to 90%). During continuous cultivation of strain B527 with cellobiose as the limiting nutrient, maximum production of the endoglucanase and cellobiase occurred at pH values of 5.2 and 4.8, respectively. In the carbon-limited continuous cultures, strain 824 produced similar levels of endoglucanase, cellobiosidase, and cellobiase activities regardless of the carbon source used. However, in ammonium- or phosphate-limited cultures, with an excess of glucose, only 1/10 of the endoglucanase was produced, and neither cellobiosidase nor cellobiase activities were detectable. A crude extracellular enzyme preparation from strain B527 hydrolyzed carboxymethylcellulose and phosphoric acid-swollen cellulose readily and microcrystalline cellulose (A vicel) to a lesser extent. Glucose accounted for more than 90% of the reducing sugar produced by the hydrolysis of acid-swollen cellulose and Avicel. Strain B527 did not grow in medium with acid-swollen cellulose as the sole source of carbohydrate, although it grew readily on the products obtained by hydrolyzing the cellulose in vitro with a preparation of extracellular cellulase derived from the same organism.     

Construction of a reporter plasmid for screening in vivo promoter activity in Francisella tularensis

Francisella tularensis is a facultative intracellular bacterium that survives and multiplies inside macrophages. Here we constructed a new promoter probe plasmid denoted pKK214 by introduction of a promoter-less chloramphenicol acetyltransferase (cat) gene into the shuttle vector pKK202. A promoter library was created in F. tularensis strain LVS by cloning random chromosomal DNA fragments into pKK214. Approximately 15% of the recombinant bacteria showed chloramphenicol resistance in vitro. The promoter library was also used to infect macrophages in the presence of chloramphenicol and after two cycles of infection the library contained essentially only chloramphenicol resistance clones which shows that pKK214 can be used to monitor F. tularensis genes that are expressed during infection.