A method using indicator plants to map local climatic variation in the Kangerlussuaq/Scoresby Sund area, East Greenland

Abstract Aim To describe a method for mapping local climatic variation using plants as temperature indicators. Location The study area is situated on the northern side near the mouth of the fiord Kangerlussuaq/Scoresby Sund, East Greenland (70–71°N). The study area consists of three subareas, divided into 136 1 × 1 km study units. It was selected because of its very strong climatic gradient as shown by data from four meteorological stations in the area, with mean July temperatures ranging from 2.7 to 9.3 °C. Methods The method is based on the fact that most vascular plant species occurring in the Arctic have circumpolar distribution patterns obviously limited by temperatures to a varying extent. By comparing the circumpolar distribution maps with summer temperatures, species are grouped according to minimum temperature demands and assigned indicator values. In the field, frequency and abundance of all indicator species and the occurrence of habitats are recorded in all study units. Indicator values and abundance data are entered into a formula of Index of Thermophily, and the resulting values are modified according to deviating habitat diversity and cover of unproductive areas. Index values are supposed to reflect local climatic conditions, and the results are tested by comparing with temperatures measured in the field. Results A total of 147 taxa, 139 of these being vascular plants, were defined in six categories of temperature indicators. The Index of Thermophily values calculated for the 136 study units show a complex pattern and a strong positive relationship with the temperatures measured during 1991 and 1993, with r² values of 0.82 and 0.92, respectively. The unmodified Index version gave slightly lower correlations. A very strong gradient is demonstrated from the extremely cold coastal community of Uunarteq/Kap Tobin to more protected sites only 20 km inland, where a similar climate is found at 1100 m altitude. Favourable slopes also produce a favourable climate at altitudes of 700 m. The warmest sites are the south‐facing slopes of five deep river gorges, all with similar Index values and the occurrence of Salix shrubs. The results are used to make a local bioclimatic map, including allowances for topographic features and detailed knowledge on the occurrence of concentrations of thermophilous plants. Here fourteen climate classes are mapped in detail, and these mapping units can be correlated to four of five subzones present in the Arctic on a circumpolar scale. The correlation with these subzones shows that the study area has the strongest horizontal climate gradient recorded from the Arctic. Main conclusions The strong positive correlation between the calculated Index of Thermophily values and measured temperatures indicate that the present method is successful in mapping local bioclimatic heterogeneity in the Arctic.     

Mycobacteria contain two groEL genes: the second Mycobacterium leprae groEL gene is arranged in an operon with groES

In contrast to other bacterial species, mycobacteria were thus far considered to contain groEL and groES genes that are present on separate loci on their chromosomes, Here, by screening a Mycobacterium leprae lambda gt11 expression library with serum from an Ethiopian lepromatous leprosy patient, two DNA clones were isolated that contain a groEL gene arranged in an operon with a groES gene. The complete DNA sequence of this groESL operon was determined. The predicted amino acid sequences of the GroES and GroEL proteins encoded by this operon are 85-90% and 59-61% homologous to the sequences from previously characterized mycobacterial GroES and GroEL proteins. Southern blotting analyses with M. leprae groES- and groEL-specific probes demonstrate that similar groESL homologous DNA is present in the genomes of other mycobacteria, including Mycobacterium tuberculosis. This strongly suggests that mycobacteria contain a groESL operon in addition to a separately arranged second groEL gene. Using five T-cell clones from two leprosy patients as probes, expression of the M. leprae GroES protein in Escherichia coli after heat shock was demonstrated. Four of these clones recognized the same M. leprae-specific GroES-derived peptide in a DR2-restricted fashion. No expression of the groEL gene from this operon was detected in E. coli after heat shock, as tested with a panel of T-cell clones and monoclonal antibodies reactive to previously described GroEL proteins of mycobacteria.     

3-Substituted indolizine-1-carbonitrile derivatives as phosphatase inhibitors

In the course of studies directed toward the discovery of novel scaffolds for medicinal application, we synthesized a series of 3-substituted indolizine-1-carbonitrile derivatives. Some of them displayed activity against MPtpA/MPtpB phosphatases which are involved in infectious diseases. We report here the solid-phase synthesis and antiphosphatase activity of a series of indolizines.     

Evaluation of angiogenesis and side effects in ischemic rabbit hindlimbs after intramuscular injection of adenoviral vectors encoding VEGF and LacZ

Background

Recent studies have suggested the therapeutic potential of vascular endothelial growth factor (VEGF) gene therapy in ischemic skeletal muscle. However, only limited information is available about the effects of VEGF gene therapy in different regions of ischemic limbs, effects of control adenoviruses, and biodistribution of the transgenes after intramuscular (i.m.) administration. Here we studied angiogenesis and side effects of adenovirus‐mediated VEGF and β‐galactosidase (LacZ) gene transfers in ischemic rabbit hindlimbs.

Methods and results

Ten days after induction of ischemia, rabbits were treated with i.m. injections of saline, LacZ adenovirus (AdLacZ; 2×10¹⁰ pfu) or adenovirus encoding mouse VEGF₁₆₄ (AdVEGF; 2×10¹⁰ pfu). In rabbits treated with AdVEGF an increase in serum VEGF₁₆₄ levels was detected by ELISA three and seven days after the gene transfer. 30 days after the gene transfer a positive effect on capillary density was observed in the thigh region both in rabbits treated with AdVEGF and AdLacZ compared with animals that received saline. On the other hand, AdVEGF and AdLacZ gene transfers had no effect on the capillary density in the calf region on day 30. A positive correlation between the capillary density and the number of collateral arteries was observed in the thigh. Hindlimb and testis edema and excess non‐physiological growth of capillaries were detected as adverse effects of the AdVEGF gene therapy. Biodistribution analysis showed that the transgene was present not only in the target muscle, but also in ectopic tissues seven days after i.m. gene transfer.

Conclusions

The results suggest that a high dose of adenoviral vector encoding either AdVEGF or AdLacZ induces angiogenesis in the rabbit hindlimb ischemia model; i.m. injection of adenovirus leads to the transfection of ectopic organs; and AdVEGF gene transfer induces edema in ischemic skeletal muscle. Copyright © 2002 John Wiley & Sons, Ltd.

     

Modeling and analysis of elution stage of biospecific adsorption in finite bath

A model is developed and used to predict the dynamic behavior of the elution stage of biospecific adsorption (affinity chromatography) in a finite bath. Both nonselective and selective elution of monovalent adsorbates is considered. The model expressions account for film and pore diffusion resistances for the adsorbate(s) and the eluent, and various rate expressions for the desorption of the adsorbate from the adsorbate-ligand complex are constructed and studied. The results indicate that the duration of the elution stage depends significantly on the Sherwood number of the adsorbate and the rate of the interaction step between the ligand and the adsorbate relative to the diffusion of the adsorbate in the pore during elution. In nonselective elution, when the value of the effective pore diffusivity of the eluent is significantly larger than that of the adsorbate, the results suggest that it would be advantageous to use an initial eluent concentration in the finite bath that is only slightly higher than the critical eluent concentration in order to minimize the risk of product and ligand damage. In selective elution the amount of adsorbate recovered in the elution stage is greatly influenced by the initial concentration of the eluent and the equilibrium dissociation constants of the adsorbate-ligand and adsorbate-eluent complexes.     

Colostral Transfer in the Goat of Antibodies Against Corynebacterium Pseudotuberculosis and the Antibody Status of Kids During the First 10 Months of Life

Serum and colostrum samples from goats at parturition and serum samples from their kids at 3 days and at 4, 7, 10 and 12 weeks after birth were examined for the presence of antibodies to Corynebacterium pseudotuberculosis hemolysins. The hemolysis inhibition test (HIT) was used. High correlation was found between titre values of antihemolysins in serum and colostrum of goats at parturition (correlation coefficient r = 0.83; P < 0.01). Intermediate correlation was found between antihemolysin titre in colostrum of goats and in the sera of their kids 3 days old (r = 0.56; 0.01 < P < 0.05). Furthermore, titre values for 3 day-old kids showed high correlation with the antihemolysin titres when the kids aged 4 and 7 weeks (r = 0.76 and 0.85, respectively; P < 0.01). Antihemolysin titres decreased linearly in kids from 3 days to 10 weeks old. Calculated half life of antibodies was 12 days. Most of the kids had detectable antibodies up to the age of 5–6 weeks. None of the kids were seropositive at 2½ months of age. Serum samples collected monthly from a group of kids chosen at random, aged 7–10 months, contained antibodies to hemolysins in half of the animals at the first testing. At the age of 10 months 14 out of 15 kids were seropositive. Thus, most of the kids from this herd were exposed to G. pseudotuberculosis antigens during summer and autumn of their first year of life. Prophylactic measures against caseous lymphadenitis is briefly discussed.     

A survey of plant associations and alliances from Svalbard

Abstract. Most vegetation classification studies on Svalbard have followed the phytosociological tradition. Exposed ridges and accumulation sea shores are the habitats investigated best, whereas the open vegetation of screes, active sedimentation plains, erosion plains, young moraines, polar desert and saxicolous vegetation range from almost unknown to poorly known. All published associations and non-ranked plant communities based on relevé data are reviewed and discussed in an ecological framework with 19 major habitat types. Most of them are arranged in a system of 17 alliances. Most of the alliances are expected to occur elsewhere in the Arctic, but this remains to be documented. The majority of the Svalbard studies are local and have obvious shortcomings. Nevertheless, vegetation types are probably better known on Svalbard than elsewhere in the northern parts of the Arctic.     

Functional inference of the methylenetetrahydrofolate reductase 677 C > T and 1298A > C polymorphisms from a large-scale epidemiological study

Two functional single nucleotide polymorphisms, 677C > T and 1298A > C have been described for the methylenetetrahydrofolate (MTHFR) gene. Both are associated with reduced enzyme activity in vitro. For the 677T, but not the 1298C allele, significantly lower serum folate and higher plasma total homocysteine (tHcy) have been reported. We genotyped 10,034 middle-aged (50–64 years old) subjects and measured serum folate and tHcy. Within strata of 677 genotypes, 1,298 genotypes had significantly different serum folate and tHcy (P ≤ 0.03 for all comparisons). Each additional 1298C allele reduced mean serum folate and increased mean tHcy, by (on average) 4.5 and 3.0%, respectively. In comparison, within strata of 1,298 genotypes, the increase from no, to one 677T-allele reduced serum folate and increased tHcy by, 7.1 and 6.3%, respectively. Lowest serum folate and highest tHcy level was found for the 677TT/1298AA genotype. The difference in tHcy was significantly larger at low folate than at high folate when genotypes 677TT/1298AA and 677CT/1298AA, 677CT/1298AC and 677CC/1298AC, and genotypes 677CT/1298AC and 677CT/1298AA were compared. We interpreted these data in the context of a model of the MTHFR enzyme that describes the enzyme as a dimer that mainly exist in six different configurations. The model reconciled the observed phenotypic effects of the 677/1,298 combination genotypes with previous in vitro measurements, and identified enzyme configurations that are sensitive to low folate levels. In conclusion, this report demonstrates functional inference of the MTHFR 677 C > T and 1,298 A > C polymorphisms from a large-scale epidemiological study.     

Feeding activity and opercular pressure transients in Atlantic salmon (<Emphasis Type="Italic">Salmo salar</Emphasis> L.): application to feeding management in fish farming

Ecological and economical sustainability of marine aquaculture operations depend on proper feeding management. Feed wastage from overfeeding is a source of pollution, represents futile use of precious marine resources, and undermines the economic viability of operations. Additionally, underfeeding reduces growth and fish welfare. Finding an optimal feeding regime in terms of temporal and spatial distribution of the feed ration require intimate knowledge of the individual feeding behaviour of fish sustaining intensive culturing conditions. Fish telemetry has proved to be a valuable tool for studying spatial behaviour in sea cages, however there are currently no practical methods available with respect to detection of actual feed intake in fish on the individual level. The present study investigates pressure transients arising in the opercular cavity of farmed Atlantic salmon (Salmo salar L.) in connection with feeding, and whether such measurements can serve as an indication of feed ingestion. A technical solution to the sensing problem based on a differential pressure transducer is presented along with typical pressure signal traces obtained during feeding in a hard wire tank experiment. Measurements showed considerable variation of sub-ambient pressure transients (1.5 kPa ± 0.95) and their duration (519 ms ± 117), suggesting that the fish modulates its strike intensity depending on the particular feeding situation. Despite variations in scale, opercular pressure waveforms have distinct structural features that repeat between feeding instants. From a signal processing point of view waveforms provide sufficient information with respect to isolation and detection of feeding incidents, which is important with respect to a potential implementation of the sensing principle in a telemetry tag design. Issues regarding development and application of a telemetry system based on this sensing principle are discussed.     

The modeling and analysis of the elution stage of biospecific adsorption in fixed beds

A mathematical model that describes the dynamic behavior of the elution stage of biospecific adsorption (affinity chromatography) in a fixed bed is developed and solved. Both non-selective and selective elution methods are considered. The results show that the duration of the elution stage for a given bed length decreases as the value of the Porath parameter for elution increases. The concentrating effect of the elution stage on the adsorbate of interest increases as the bed length and the value of the Porath parameter for elution increase. It is shown that it is inappropriate to assume that the eluent is infinitely fast distributed within the pores of the particles, and an interesting result involving a local maximum in the effluent concentration of the selective eluent is obtained when the direction of flow in the elution stage is the same as in the adsorption and wash stages and the bed length is large. When the direction of flow during elution is opposite (as compared to being the same) to that employed in the adsorption and wash stages, a shorter total elution time is obtained. The advantage gained with a reversed flow increases as the bed length decreases.