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M B Pedersen

Publications and source records attributed to M B Pedersen.

15 recordsLinked to original sources
PubMed1998

Structure and genetic stability of mitochondrial genomes vary among yeasts of the genus Saccharomyces.

Several yeast species/isolates belonging to the genus Saccharomyces were examined for the organization of their mtDNAs and ability to generate petite mutants. A general characteristic for all of the mtDNAs tested was that they were very A+T-rich. However, restriction patterns and inducibility of petite mutations revealed a great diversity in the organization and genetic behaviour of mtDNAs. One group of yeasts, Saccharomyces sensu stricto, contains mtDNA ranging in size from 64 to 85 kb. mtDNAs form these yeasts contain a high number of restriction sites that are recognized by the enzymes Haelll and Mspl, which cut specifically in G+C clusters. There are three to nine ori/rep sequences per genome. These yeasts spontaneously generate respiration deficient mutants. Ethidium bromide (Et-Br), at low concentrations, induces a majority of cells to give rise to petites. A second group of yeasts, Saccharomyces sensu lato, contains smaller mtDNAs, ranging in size from 23 to 48 kb, and probably only a few intergenic G+C clusters and no ori/rep sequences. These yeasts also generate petite clones spontaneously. but Et-Br, even when present at high concentrations, does not substantially increase the frequency of petites. In most petite clones from these yeasts only a small fragment of the wild-type molecule is retained and apparently multiplied. A third group, represented by Saccharomyces kluyveri, does not give rise to petite mutants either spontaneously or after induction.

Base Composition↗
PubMed1997

Saccharomyces carlsbergensis contains two functional genes encoding the acyl-CoA binding protein, one similar to the ACB1 gene from S. cerevisiae and one identical to the ACB1 gene from S. monacensis.

Saccharomyces carlsbergensis is an amphiploid, and it has previously been suggested that the genomes of S. carlsbergensis originate from S. cerevisiae and S. monacensis. We have cloned the ACB1 genes encoding the acyl-CoA binding protein (ACBP) from S. carlsbergensis, S. cerevisiae and S. monacensis. Two genes were found in S. carlsbergensis and named ACB1 type 1 and type 2, respectively. The type 1 gene is identical to the S. cerevisiae ACB1 gene except for three substitutions, one single base pair deletion and one double base pair insertion, all located in the promoter region. The type 2 gene is completely identical to the S. monacensis ACB1 gene. These findings substantiate the notion that S. carlsbergensis is a hybrid between S. cerevisiae and S. monacensis. Both ACB1 type 1 and type 2 are actively transcribed in S. carlsbergensis and transcription is initiated at sites identical to those used for transcriptional initiation of the ACB1 genes in S. cerevisiae and S. monacensis, respectively. Two polyadenylation sites, spaced 225 bp apart, are present in the S. cerevisiae ACB1 gene. The upstream polyadenylation site is used exclusively during exponential growth, whereas both sites are utilized during later stages of growth.

Base Sequence↗
PubMed1997

Ecological effects assessment of industrial sludge for microarthropods and decomposition in a spruce plantation.

Effects of dried, granulated industrial sludge-containing residues of organic pesticides and precursors were assessed for microarthropod fauna and the decomposition of a spruce forest floor. The investigation was highly realistic, using large plots of about 1/2 ha, and the application was done with professional equipment. The ecological effects of the sludge were compared with the ecological effects of an inorganic fertilizer. Decreases in abundance of the microarthropods ranged from 20 to 80% of the control level after 1 year. Isotoma notabilis Schäffer was the only species that exhibited stimulation at twice the control level due to the sludge. The least affected collembolan species was Lepidocyrtus cyaneus Tullberg, a member of the surface-dwelling life forms. Sensitive species were Isotoma anglicana Lubbock and Isotomiella minor Schäffer. In subhabitats with almost no application of sludge due to a heterogeneous horizontal distribution, the microarthropods were still affected to the same degree as those in the zones of maximum application. Laboratory tests with Folsomia candida Willem gave results similar to the effects on field populations concerning the sludge but revealed no adverse effects of the fertilizer. Decomposition was stimulated to the same extent in the field by the two types of fertilizer but in the laboratory the sludge caused the largest stimulation. The effects on the microarthropod fauna are suggested to be the result of a combination of direct toxicity and changes in the microbial community due to fertilizers.

Animals↗
PubMed1995

A national cross-sectional study in the Danish wood and furniture industry on working postures and manual materials handling.

Musculoskeletal disorders constitute a major problem in the wood and furniture industry and identification of risk factors is needed urgently. Therefore, exposures to different work tasks and variation in the job were recorded based on an observation survey in combination with an interview among 281 employees working in wood working and painting departments. A questionnaire survey confirmed high frequencies of symptoms from the musculoskeletal system: The one-year prevalence of symptoms from the low back was 42% and symptoms from the neck/shoulder was 40%. The exposure was evaluated based on: (1) classification of work tasks, (2) work cycle time, (3) manual materials handling, (4) working postures, and (5) variation in the job. Among the employees 47% performed feeding or clearing of machines, 35% performed wood working or painting materials, and 18% performed various other operations. Among the employees 20% had no variation in their job while 44% had little variation. Manual materials handling of 375 different burdens was observed, which most often occurred during feeding or clearing of machines. The weight of burdens lifted was 0.5-87.0 kg, where 2% had a weight of more than 50 kg. Among the lifting conditions 30% were evaluated as implying a risk of injury. An additional risk factor was the high total tonnage lifted per day, which was estimated to range from 132 kg to 58,800 kg. Working postures implied a risk of injury due to prolonged forward and lateral flexions of the neck, which was seen most frequently during wood working or painting materials. These data substantiate the finding that work tasks mainly during feeding or clearing of machines imply a risk of injury to the low back and a risk of injury to the neck and shoulder area mainly during wood working or painting materials. Optimal strategies for job redesign may be worked out by using these data in order to prevent occupational musculoskeletal disorders.

Adolescent↗
PubMed1995

A mitochondrial molecular marker, ori-rep-tra, for differentiation of yeast species.

Yeasts exhibit various mechanisms for the inheritance of their mitochondrial genomes. Differences among these mechanisms are based on variations within nuclear as well as mitochondrial genetic elements. Here we report diagnostic differences in the presence of biologically active mitochondrial intergenic sequences, ori-reptra, among related yeasts in the genera Saccharomyces, Arxiozyma, Debaryomyces, Kluyveromyces, Pachytichospora, Torulaspora, and Zygosaccharomyces. A molecular probe containing ori-rep-tra can be employed specifically for the differentiation and identification of isolates belonging to the species complex Saccharomyces sensu stricto.

DNA, Mitochondrial↗
PubMed1993

The dominant mutation Suppressor of black indicates that de novo pyrimidine biosynthesis is involved in the Drosophila tan pigmentation pathway.

A deficiency in the production of beta-alanine causes the black (b) phenotype of Drosophila melanogaster. This phenotype is normalized by a semi-dominant mutant gene Su(b) shown previously to be located adjacent to or within the rudimentary (r) locus. The r gene codes for three enzyme activities involved in de novo pyrimidine biosynthesis. Pyrimidines are known to give rise to beta-alanine. However, until recently it has been unclear whether de novo pyrimidine biosynthesis is directly coupled to beta-alanine synthesis during the tanning process. In this report we show that flies carrying Su(b) can exhibit an additional phenotype, resistance to toxic pyrimidine analogs (5-fluorouracil, 6-azathymine and 6-azauracil). Our interpretation of this observation is that the pyrimidine pool is elevated in the mutant flies. However, enzyme assays indicate that r enzyme activities are not increased in Su(b) flies. Genetic mapping of the Su(b) gene now places the mutation within the r gene, possibly in the carbamyl phosphate synthetase (CPSase) domain. The kinetics of CPSase activity in crude extracts has been studied in the presence of uridine triphosphate (UTP). While CPSase from wild-type flies was strongly inhibited by the end-product, UTP, CPSase from Su(b) was inhibited to a lesser extent. We propose that diminished end-product inhibition of de novo pyrimidine biosynthesis in Su(b) flies increases available pyrimidine and consequently the beta-alanine pool. Normalization of the black phenotype results.

Animals↗
PubMed1992

Long-term psychosocial adjustment in patients with severe burn injuries: a follow-up study.

An investigation of the long-term psychosocial adjustment of patients with severe burn injuries is presented. In the selected 13-year period (1968-80) 46 patients fulfilled the entry criteria: burns covering more than 30 per cent body surface area (deep dermal or full skin thickness). Seventeen patients died early and one later. Of the remaining 28 patients, contact was made with 25 (89.3 per cent) who all participated. The observation time ranged between 7 and 21 years. The patients received a semi-standardized interview adjusted for age at the time of burn injury, a psychiatric interview and a physical examination to assess the permanent character and functional loss. The principal findings were: no correlation could be found between degree of disfiguration/function loss and the long-term psychosocial adaptation after severe burn injuries. The determinant factor was the premorbid psychiatric/psychological integration and, to some extent, support from staff and relatives.

Adaptation, Psychological↗
PubMed1989

[Persons aged 65 years and over admitted to the medical department of a hospital in the Danish provinces with 4 specialized departments. An analysis of extra days of hospitalization related to the services for senior citizens in 4 communities].

In a retrospective investigation of year 1985, it was found that out of 438 medical patients greater than or equal to 65 years there were in all 42 patients who together were responsible for 1,543 bed-days after the time when they were considered to have concluded hospital treatment. The extra bed-days correspond to approximately 9% of the total medical bed capacity. The patients came from four communities whose coverage with nursing homes, home nursing services and home help arrangements were very different. It was found that increase in nursing home capacity was followed by decrease in the number of extra bed-days among the patients who had extra bed-days. When the number of home nurses increased, fewer elderly patients from the community concerned, were admitted who ended by having extra long hospitalization. These conditions are discussed and the results are compared with previously published investigations. It is concluded that improved cooperation between communities and hospitals, is required.

Aftercare↗
PubMed1989

The cerebral arterio-venous oxygen content differences (AVDO2) during halothane and neurolept anaesthesia in patients subjected to craniotomy.

In 20 patients subjected to craniotomy for supratentorial cerebral tumours, the haemodynamic changes during halothane and neurolept anaesthesia were evaluated by measuring mean arterial blood pressure (MABP) and cerebral arterio-venous oxygen content differences (AVDO2) repeatedly during the operation. Ten patients were given 0.5% halothane anaesthesia and ten patients neurolept anaesthesia. MABP, AVDO2 and PaCO2 were measured after induction of anaesthesia, before and after incision, after opening and closure of the dura, at the time of extubation and 1 h later. Concerning MABP and PaCO2, no significant difference between the two groups was found. In both groups an increase in MABP was observed after incision (P less than 0.01 in the neurolept group and P less than 0.05 in the halothane group) and in the neurolept group after extubation (P less than 0.01). In both groups a decrease in AVDO2 was observed after incision (P less than 0.01) and after extubation (P less than 0.01 in the neurolept group and P less than 0.05 in the halothane group). During the operation AVDO2 values were significantly higher in the neurolept group (P less than 0.05). The results indicate that even a moderate increase in MABP after incision during neuroanaesthesia affects AVDO2 values, suggesting an increase in cerebral blood flow. The study suggests that autoregulation of cerebral blood flow might be better preserved during neurolept anaesthesia. A state of hyperperfusion of the brain after extubation was unveiled in both groups.

Adult↗
PubMed1988

DNA sequence polymorphisms in the genus Saccharomyces. V. Cloning and characterization of a LEU2 gene from S. carlsbergensis.

Saccharomyces carlsbergensis strains used in the production of lager beer are structurally heterozygous in most genetic loci studied to date. Previous studies have shown that the genotype of lager yeast contains two types of genomes, one of which is derived from S. cerevisiae and the other reveals similarities to the genomes of S. bayanus and S. monacensis. Genes of homeologous chromosomes can be distinguished by characteristic restriction fragment patterns. This is true also for the LEU2 genes which encode the beta-isopropylmalate dehydrogenase and are located on chromosomes III. In the present work a LEU2 gene from S. carlsbergensis has been cloned and characterized. The cloned 2.6 kb LEU2 region complements the S. cerevisiae leu2-3 leu2-112 double mutation. The restriction endonuclease site map of the isolated S. carlsbergensis LEU2 gene is different from that of the S. cerevisiae LEU2 gene. Electrophoretic chromosome separation, as well as karl mediated transfer of single chromosomes into S. cerevisiae strains, has shown that the S. carlsbergensis specific LEU2 gene is located on a chromosome III which carries the carlsbergensis specific HIS4 gene. The cloned LEU2 gene shows preferential molecular hybridization to one of the two LEU2 structural alleles present in lager strains, an allele which is also present in type strains of S. bayanus, S. carlsbergensis, S. monacensis and S. uvarum.

Alleles↗
PubMed1988

Cerebral blood flow, cerebral metabolic rate of oxygen and relative CO2 reactivity during neurolept anaesthesia in patients subjected to craniotomy for supratentorial cerebral tumours.

In 10 patients subjected to craniotomy for supratentorial cerebral tumours in neurolept anaesthesia, cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) were measured twice peroperatively by a modification of the Kety & Schmidt technique, using 133Xe. The relative CO2 reactivity was assessed indirectly as the % change of the arteriovenous oxygen difference (AVDO2) per mm change in PaCO2. The patients were premedicated with diazepam 10-15 mg perorally. For induction, thiopentone 4-6 mg/kg, droperidol 0.2 mg/kg and fentanyl 5 micrograms/kg were used, and for maintenance N2O 67% and fentanyl 4 micrograms/kg/h. During the first flow measurement the median and range of CBF was 30 ml/100 g/min (range 17-45), of AVDO2 8.0 vol % (range 4.1-9.5), and of CMRO2 2.28 ml O2/100 g/min (range 1.57-2.84). During the second CBF study, AVDO2 increased to 9.3 vol % (range 3.4-11) (P less than 0.05), and CMRO2 increased to 2.51 ml O2/100 g/min (range 1.88-3.00) P less than 0.05, while CBF was unchanged. The CO2 reactivity was present in all studies, median 1.8%/mmHg (range 0.5-15.1). The correlation coefficients between jugular venous oxygen tension/saturation, respectively, and CBF were high at tensions/saturations exceeding 4.0 kPa and 55%, indicating that hyperperfusion is easily unveiled by venous samples from the jugular vein during this anaesthesia.

Adult↗