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Biomedical subjects

K Lindström

Publications and source records attributed to K Lindström.

At least 19 recordsLinked to original sources
PubMed2001

Genetic diversity of rhizobia isolated from Astragalus adsurgens growing in different geographical regions of China.

The genetic diversity among 95 isolates from Astragalus adsurgens was investigated using molecular biological methods. All of the isolates and 24 reference strains could be differentiated by AFLP, REP-, ERIC- and BOX-PCR fingerprinting analysis. By cluster analysis of the data, 31 AFLP and 38 Rep-PCR genomic groups were delineated, indicating considerable genetic diversity among the isolates. Fifty-four representative strains were further analyzed by RFLP of PCR-amplified 16S and 23S rDNA, revealing 26 rDNA genotypes among the isolates. The phylogenetic relationship of the isolates was determined by partial sequencing of 16S rRNA genes of 16 strains. The results suggest that the A. adsurgens rhizobia belong to the genera Agrobacterium, Mesorhizobium, Rhizobium and Sinorhizobium.

Astragalus Plant↗
PubMed2001

AFLP fingerprinting as a tool to study the genetic diversity of Rhizobium galegae isolated from Galega orientalis and Galega officinalis.

AFLP fingerprints of Rhizobium galegae strains that infect Galega orientalis and Galega officinalis obtained from different geographical sources, and of taxonomically diverse rhizobia representing the recognized species, were generated. Comparisons of the fingerprints from fluorescent labeled AFLP products using capillary electrophoresis on ABI prism 310, slab gel electrophoresis on ABI prism 377 genetic analyzers and silver staining were in good agreement. All methods delineated the G. orientalis strains from G. officinalis strains, the G. orientalis strains formed a tight cluster whereas the G. officinalis strains seem to show a greater level of genetic diversity. Comparison of fluorescent AFLP with other detection methods revealed that fluorescent labeling is more sensitive and practical, in addition, the deleterious effect of radioactivity associated with 32P-labeling, the delicate process of blotting polyacrylamide gels or the tedious procedure of silver staining can be avoided. The automated system facilitated a large number of runs at a time and the subsequent analysis of the data by generating exportable raw data. The congruency of the experiments was analyzed using the Bionumerics software.

DNA Fingerprinting↗
PubMed2001

How cuckoldry can decrease the opportunity for sexual selection: data and theory from a genetic parentage analysis of the sand goby, Pomatoschistus minutus.

Alternative mating strategies are common in nature and are generally thought to increase the intensity of sexual selection. However, cuckoldry can theoretically decrease the opportunity for sexual selection, particularly in highly polygamous species. We address here the influence of sneaking (fertilization thievery) on the opportunity for sexual selection in the sand goby Pomatoschistus minutus, a marine fish species in which males build and defend nests. Our microsatellite-based analysis of the mating system in a natural sand goby population shows high rates of sneaking and multiple mating by males. Sneaker males had fertilized eggs in approximately 50% of the assayed nests, and multiple sneakers sometimes fertilized eggs from a single female. Successful males had received eggs from 2 to 6 females per nest (mean = 3.4). We developed a simple mathematical model showing that sneaking in this polygynous sand goby population almost certainly decreases the opportunity for sexual selection, an outcome that contrasts with the usual effects of cuckoldry in socially monogamous animals. These results highlight a more complex and interesting relationship between cuckoldry rates and the intensity of sexual selection than previously assumed in much of the literature on animal mating systems.

Animals↗
PubMed2001

Extraction and purification of DNA in rhizosphere soil samples for PCR-DGGE analysis of bacterial consortia.

Application of DNA fingerprinting methods enables the detection of diverse members of soil bacterial consortia, even including those bacteria not yet cultivated. However, extraction and purification of DNA from soil samples without bias is difficult. We compared five different DNA isolation methods and three purification methods for rhizosphere soil samples. Purified DNA extracts were amplified in PCR using universal bacterial primers and the PCR products were analysed with denaturing gradient gel electrophoresis (DGGE) for the visualisation of DNA bands representing dominant bacterial species. Both the isolation and purification methods affected the apparent bacterial community structure of the samples.

Bacteria↗
PubMed2001

Effect of heat stress on cell activity and cell morphology of the tropical rhizobium, Sinorhizobium arboris.

The effect of heat stress on the growth, physiological state, cell activity and cell morphology of the tropical Sinorhizobium arboris strain HAMBI 2190 was studied. The cells were chromosomally tagged with the firefly luciferase gene, luc. Since the bioluminescence phenotype is dependent on cellular energy reserves it was used as an indicator of the metabolic status of the cell population under various heat conditions. Variations in the numbers and lengths of growth phases between individual cultures indicated that the growth pattern at 40 degrees C was disturbed compared to growth at 37 or 28 degrees C. In addition, the cell morphology was changed radically. The number of culturable cells and the luciferase activity declined when the cultures were incubated at 40 degrees C. By contrast, under all conditions studied, the cells could be stained with 5-(and 6-)sulfofluorescein diacetate, indicating esterase activity. This demonstrated that although the culturability and cellular energy reserves decreased considerably during heat stress, a majority of the of S. arboris cell population maintained basal enzyme activity.

Journal Article↗
PubMed2001

Surprising similarity of sneaking rates and genetic mating patterns in two populations of sand goby experiencing disparate sexual selection regimes.

Molecular markers have proved extremely useful in resolving mating patterns within individual populations of a number of species, but little is known about how genetic mating systems might vary geographically within a species. Here we use microsatellite markers to compare patterns of sneaked fertilization and mating success in two populations of sand goby (Pomatoschistus minutus) that differ dramatically with respect to nest-site density and the documented nature and intensity of sexual selection. At the Tvärminne site in the Baltic Sea, the microsatellite genotypes of 17 nest-tending males and mean samples of more than 50 progeny per nest indicated that approximately 35% of the nests contained eggs that had been fertilized by sneaker males. Successful nest holders mated with an average of 3.0 females, and the distribution of mate numbers for these males did not differ significantly from the Poisson expectation. These genetically deduced mating-system parameters in the Tvärminne population are remarkably similar to those in sand gobies at a distant site adjoining the North Sea. Thus, pronounced differences in the ecological setting and sexual selection regimes in these two populations have not translated into evident differences in cuckoldry rates or other monitored patterns of male mating success. In this case, the ecological setting appears not to be predictive of alternative male mating strategies, a finding of relevance to sexual selection theory.

Animals↗
PubMed2001

Description of two biovars in the Rhizobium galegae species: biovar orientalis and biovar officinalis.

Twenty-six Rhizobium galegae strains, representing the center of origin of the host plants Galega orientalis and G. officinalis as well as other geographic regions, were used in a polyphasic analysis of the relationships of R. galegae strains. Phage typing, lipopolysaccharide (LPS) profiling, pulsed field gel electrophoresis (PFGE) profiling and rep-PCR (use of repetitive sequences as PCR primers for genomic fingerprinting) with REP and ERIC primers investigated nonsymbiotic properties, whereas plasmid profiling and hybridisation with a nif gene probe, and with nodB, nodD, nod box and an IS sequence from the symbiotic region as probes, were used to reveal the relationships of symbiotic genes. The results were used in pairwise calculations of distances between the strains, and the distances were visualised as a dendrogram. Indexes of association were compared for all tests pooled, and for chromosomal tests and symbiotic markers separately, to display the input of the different categories of tests on the grouping of the strains. Our study shows that symbiosis related genetic traits in R. galegae divide strains belonging to the species into two groups, which correspond to strains forming an effective symbioses with G. orientalis and G. officinalis respectively. We therefore propose that Rhizobium galegae strains forming an effective symbiosis with Galega orientalis are called R. galegae bv. orientalis and strains forming an effective symbiosis with Galega officinalis are called R. galegae bv. officinalis.

Bacterial Typing Techniques↗
PubMed2001

Identification and structure of the Rhizobium galegae common nodulation genes: evidence for horizontal gene transfer.

Rhizobia are soil bacteria able to fix atmospheric nitrogen in symbiosis with leguminous plants. In response to a signal cascade coded by genes of both symbiotic partners, a specific plant organ, the nodule, is formed. Rhizobial nodulation (nod) genes trigger nodule formation through the synthesis of Nod factors, a family of chitolipooligosaccharides that are specifically recognized by the host plant at the first stages of the nodulation process. Here, we present the organization and sequence of the common nod genes from Rhizobium galegae, a symbiotic member of the RHIZOBIACEAE: This species has an intriguing phylogenetic position, being symbiotic among pathogenic agrobacteria, which induce tumors instead of nodules in plant shoots or roots. This apparent incongruence raises special interest in the origin of the symbiotic apparatus of R. galegae. Our analysis of DNA sequence data indicated that the organization of the common nod gene region of R. galegae was similar to that of Sinorhizobium meliloti and Rhizobium leguminosarum, with nodIJ downstream of nodABC and the regulatory nodD gene closely linked to the common nod operon. Moreover, phylogenetic analyses of the nod gene sequences showed a close relationship especially between the common nodA sequences of R. galegae, S. meliloti, and R. leguminosarum biovars viciae and trifolii. This relationship in structure and sequence contrasts with the phylogeny based on 16S rRNA, which groups R. galegae close to agrobacteria and separate from most other rhizobia. The topology of the nodA tree was similar to that of the corresponding host plant tree. Taken together, these observations indicate that lateral nod gene transfer occurred from fast-growing rhizobia toward agrobacteria, after which the symbiotic apparatus evolved under host plant constraint.

Bacterial Proteins↗
PubMed2001

Evaluation of "Live for Life", a health promotion programme in the County of Skaraborg, Sweden.

STUDY OBJECTIVE: To evaluate a health promotion programme, combining a population and individual based strategy, in the County of Skaraborg, Sweden, with special attention to outcome. DESIGN: The evaluation was subdivided into structure, process and outcome. The evaluation procedure as a total is described here, but the results presented refer only to outcome. In order to study the potential effect of the individually based health examination, 35 year old subjects who had participated five years previously were in 1994-1996 compared with 35 year old subjects who had not participated before, and compared with their own values five years earlier. The results during 1995-1996 were compared with those of 1989-1990 for corresponding ages in order to study the effect of, particularly, the population based strategy. SETTING: The County of Skaraborg in the south western part of Sweden with about 270 000 inhabitants. In addition to population strategy, involving the total county, men and women aged 30 and 35 years were invited to an individually based examination. MAIN RESULTS: Factors related to body weight increased during the study period, while other factors mostly changed in the direction wanted. As a whole the changes were rather modest. There were favourable changes in lifestyle variables, for example, concerning smoking and dietary habits. CONCLUSIONS: There were beneficial effects from the health promotion programme, but there is a need for continuous improvement of methods of intervention referred to lifestyle.

Adult↗
PubMed2001

Effects of filtration rate on the glomerular barrier and clearance of four differently shaped molecules.

The effect of shape on the transglomerular passage of solutes has not been hitherto systematically studied. We perfused isolated rat kidneys to determine the fractional clearances (theta) at various filtration rates for four molecules of different shapes but with similar Stokes-Einstein radii (aSE = 34-36 A). The theta for hyaluronan, bikunin, and Ficoll36 A were 66, 16, and 11%, respectively, at a glomerular filtration rate (GFR) of 0.07 ml x min(-1) x g wet wt(-1) and decreased to 46, 14, and 7%, respectively, on a fivefold increase in GFR. Under the same conditions, theta for albumin increased from 0.15 to 0.74%, and similar behavior was observed for larger Ficolls (aSE >45 A). Pore analysis showed that the "apparent neutral" solute radii of Ficoll, albumin, bikunin, and hyaluronan were 35, 64, 33, and 24 A, respectively, despite similar aSE. In addition, the properties of the glomerular filter changed with increasing GFR and hydrostatic pressure. We conclude that elongated shape, irrespective of size and charge, drastically increases the transglomerular passage of a solute, an effect that is related to its frictional ratio.

Albumins↗
PubMed2000

Lack of tolerance to motor stimulant effects of a selective adenosine A(2A) receptor antagonist.

It is well known that tolerance develops to the actions of caffeine, which acts as an antagonist on adenosine A(1) and A(2A) receptors. Since selective adenosine A(2A) antagonists have been proposed as adjuncts to 3,4-dihydroxyphenylalanine (L-DOPA) therapy in Parkinson's disease we wanted to examine if tolerance also develops to the selective A(2A) receptor antagonist 5-amino-7-(2-phenylethyl)-2-(2-furyl)-pyrazolo-[4,3-e]-1,2, 4-triazolo [1,5-c]pyrimidine (SCH 58261). SCH 58261 (0.1 and 7.5 mg/kg) increased basal locomotion and the motor stimulation afforded by apomorphine. Neither effect was subject to tolerance following long-term treatment with the same doses given intraperitoneally twice daily. There were no adaptive changes in A(1) and A(2A) adenosine receptors or their corresponding messenger RNA or in dopamine D(1) or D(2) receptors. These results demonstrate that the tolerance that develops to caffeine is not secondary to its inhibition of adenosine A(2A) receptors. The results also offer hope that long-term treatment with an adenosine A(2A) receptor antagonist may be possible in man.

Animals↗
PubMed2000

Characterization of air-coupled ultrasound transducers in the frequency range 40 kHz-2 mHz using light diffraction tomography.

The aim of this work was to show the applicability of light diffraction tomography on airborne ultrasound in the frequency range 40 kHz-2 MHz. Seven different air-coupled transducers were measured to show the method's performance regarding linearity, absolute pressure measurements, phase measurements, frequency response, S/N ratio and spatial resolution. A calibrated microphone and the pulse-echo method were used to evaluate the results. The absolute measurements agreed within the calibrated microphone's uncertainty range. Pulse waveforms and corresponding FFT diagrams show the method's higher bandwidth compared with the microphone. Further, the method offers non-perturbing measurements with high spatial resolution, which was especially advantageous for measurements close to the transducer surfaces. The S/N ratio was higher than or in the same range as that of the two comparison methods.

Air↗
PubMed2000

Silver stained polyacrylamide gels and fluorescence-based automated capillary electrophoresis for detection of amplified fragment length polymorphism patterns obtained from white-rot fungi in the genus Trametes.

Silver stained denaturing polyacrylamide gels (PAGEs) and fluorescent denaturing automated capillary electrophoresis (CE) were used to detect amplified fragment length polymorphism (AFLP) patterns obtained from white-rot fungi belonging to the genus Trametes. AFLP fingerprinting detected by the fluorescence-based method as well as by silver staining showed a high discriminatory power in differentiating nine strains of Trametes ochracea, nine strains of Trametes hirsuta and ten isolates of Trametes versicolor. UPGMA dendrograms derived from fluorescently labelled and silver stained AFLP patterns were similar, but a few differences were detected especially in the clustering of T. ochracea and T. hirsuta strains. Compared to silver-stained AFLP, detection of fluorescent AFLP was fast, reliable and easy to perform and it facilitated surveying with a computerized analysis system. Fluorescent CE seems to be well suited for studying similarity between Trametes species.

Basidiomycota↗
PubMed2000

Quality improvement in primary health care using computerised journal, exemplified by a smoking cessation programme for diabetic patients.

OBJECTIVE: To study the possibility of using the computerised journal for quality improvement in diabetes care. DESIGN: The computerised journal was used to reach all diabetic smokers aged 30-75 years and to invite them to a structured smoking cessation programme. The follow-up time was 18 months. SETTING: Habo, a Swedish community with 9600 inhabitants, with one primary health care centre. SUBJECTS: 147 subjects, aged 30-75 years, were registered with the diagnosis of diabetes mellitus in the computerised journal at the primary health care centre. Altogetber 25 of these patients were registered as smokers in the journal. All of them were invited to a smoking cessation group. RESULTS: Information about smoking habits in the journal was available for all but 11%. After 18 months' follow-up, 9 of the 14 patients (64%) who started in the smoking cessation group had become non-smokers. Of those 11 subjects who did not attend the group, 6 had stopped smoking during the follow-up time in spite of not participating in the structured programme. CONCLUSION: The computerised journal is a useful tool for quality improvement, giving the opportunity for directed preventive efforts on selected patient groups.

Adult↗
PubMed2000

Analysis of cellular fatty acids and phenotypic relationships of Agrobacterium, Bradyrhizobium, Mesorhizobium, Rhizobium and Sinorhizobium species using the Sherlock Microbial Identification System.

Previous studies have demonstrated that cellular fatty acid analysis is a useful tool for identifying unknown strains of rhizobia and establishing taxonomic relationships between the species. In this study, the fatty acid profiles of over 600 strains belonging to the genera Agrobacterium, Bradyrhizobium, Mesorhizobium, Rhizobium and Sinorhizobium were evaluated using the gaschromatography-based Sherlock Microbial Identification System (MIS). Data collected with the MIS showed that the three phylogenetically defined biovars of the genus Agrobacterium formed discrete clusters, whilst species belonging to the genus Mesorhizobium formed three subclusters which were easily distinguished. These three subclusters contained Mesorhizobium ciceri and Mesorhizobium mediterraneum, Mesorhizobium tianshanense fatty acid group I and Mesorhizobium plurifarium, and Mesorhizobium huakuii and Mesorhizobium loti. The genus Sinorhizobium was composed of an individual position for Sinorhizobium meliloti and a large cluster comprising Sinorhizobium fredii, Sinorhizobium saheli, Sinorhizobium terangae, Sinorhizobium kostiense and Sinorhizobium arboris. S. meliloti contained significantly higher levels of the fatty acid 19:0 cyclo omega 8 cis and clustered with Rhizobium sp. (Hedysarum coronarium). However, discrimination between the species of genera Sinorhizobium and Rhizobium was a function of the concentration of 16:0 3-OH. The genus Rhizobium contained a single cluster containing Rhizobium sp. (Hedysarum coronarium), Rhizobium gallicum, Rhizobium leguminosarum and Rhizobium etli, along with individual positions for Rhizobium giardinii, Rhizobium tropici, Rhizobium galegae and Rhizobium hainanense. R. tropici and R. hainanense exhibited similarity to Agrobacterium biovar 2, whilst R. galegae was similar to Agrobacterium biovar 1. R. giardinii appeared unique, with comparatively little similarity to the other species. Analysis of the genus Bradyrhizobium revealed large differences from the other genera studied. Two subgroups of Bradyrhizobium elkanii were detected and easily distinguished from Bradyrhizobium japonicum. Bradyrhizobium liaoningense and Bradyrhizobium sp. (Arachis hypogaea), a group isolated from Chinese peanut plants, showed similarities to B. japonicum, whilst a subgroup of M. tianshanense appeared identical to Bradyrhizobium sp. (Arachis hypogaea).

Bacterial Typing Techniques↗
PubMed2000

An ultrasonic method for noninvasive estimation of vascular impedance to an absolute level: in vitro validation of the relationship between impedance and phase velocity.

Vascular impedance is a quantity that characterizes the properties of the vascular bed. Assuming Newtonian fluid, laminar flow and linear system, impedance is related to phase velocity. The agreement between theoretical relationship and measured data is evaluated in an in vitro study. The setup consist of a computer-controlled flow generator, a variable fluid impedance and a measuring section. Phase velocity is calculated from multiple recorded vessel pulsations detected by ultrasonic pulse-echo technique. The reference impedance is calculated from simultaneously measured high-fidelity pressure and flow data. The impedance is analyzed in the range of 1-40 Hz with 1-Hz resolution. The evaluation of the noninvasive ultrasonic technique is focused on the resonance frequencies and the characteristic impedance. No significant difference (p > 0.05) is found in the resonance frequencies nor in the characteristic impedance. However, the impedance below 5 Hz is underestimated and the extension of the measuring section causes spatial averaging effects with reduced frequency resolution.

Analysis of Variance↗
PubMed2000

The evolution of filial cannibalism and female mate choice strategies as resolutions to sexual conflict in fishes.

Filial cannibalism (the consumption of one's own viable offspring) is common among fish with paternal care. In this study, I use a computer simulation to study simultaneous evolution of male filial cannibalism and female mate choice. Under certain conditions, selection on parental males favors filial cannibalism. When filial cannibalism increases a male's probability to raise the current brood successfully, filial cannibalism also benefits the female. However, when egg eating is a male investment into future reproduction, a conflict between female and male interests emerges. Here I investigate how female discrimination against filial cannibals affects evolution of filial cannibalism and how different female choice criteria perform against filial cannibalism. The introduction of discriminating females makes the fixation of filial cannibalism less likely. I introduced three different female choice criteria: (1) females who could discern a male's genotype, that is, whether the male was going to eat eggs as an investment in future reproductive events; (2) energy-choosing females that preferred to mate with males who had enough energy reserves to live through the current brood cycle without consuming eggs; and (3) females that preferred to mate with already mated males, that is, males with eggs in their nest. Genotype choice never coexisted with filial cannibals at fixation and filial cannibals were unable to invade a population with genotype-choosing females. Energy choice was successful only when males had high energy reserves and were less dependent on filial cannibalism as an alternative energy source. The egg choosers frequently coexisted with the cannibals at fixation. When the female strategies were entered simultaneously, the most frequent outcome for low mate sampling costs was that both the cannibals and the egg choice was fixed and all other strategies went extinct. These results suggest that sexual conflicts may not always evolve toward a resolution of the conflict, but sometimes the stable state retains the conflict. In the present case, this was because the egg-preference strategy had a higher fitness than the other female strategies. The outcome of this simulation is similar to empirical findings. In fish with paternal care, male filial cannibalism and female preference for mates with eggs commonly co-occur.

Animals↗