Effects of diverse environmental conditions on {phi}LC3 prophage stability in Lactococcus lactis

The effects of various growth conditions on spontaneous phiLC3 prophage induction in Lactococcus lactis subsp. cremoris IMN-C1814 was analyzed with a half fraction of a 4(4) factorial experimental design. The four factors included in the study were nutrient availability, acidity, osmolarity, and temperature, each applied at four levels. These environmental factors are related to the fermentation processes in the dairy industry, in which bacteriophage attacks on sensitive starter strains are a constant threat to successful fermentation processes. The frequency of spontaneous phiLC3 induction was determined by quantitative analyses of restored DNA attachment sites (attB) on the bacterial chromosomes in a population of lysogenic cells. Statistical analysis revealed that all four environmental factors tested affected phiLC3 prophage stability and that the environmental factors were involved in interactions (interactions exist when the effect of one factor depends on the level of another factor). The spontaneous phiLC3 induction frequency varied from 0.08 to 1.76%. In general, the induction frequency remained at the same rate or decreased when level 1 to 3 of the four environmental factors was applied. At level 4, which generally gave the least favorable growth conditions, the induction frequency was either unchanged, decreased, or increased, depending on the type of stress. It appeared that the spontaneous induction frequency was independent of the growth behavior of the host. It was the environmental growth conditions that were the decisive factor in induction frequency.     

Direct and indirect mate choice on leks

Indirect mate choice is any behavior that restricts the individual's set of potential mates without discrimination of mate attributes directly, for example, by having preferences about where to mate. We analyzed a 14-year data set from great snipe (Gallinago media) leks for evidence of indirect mate choice based on relative and absolute position of lek territories. We found little or no effect of the centrality of territories on mating and no between-year consistency in the spatial distribution of matings within leks. Instead, the probability of matings occurring at a particular site increased if the current territory owner had mated the previous year. Furthermore, individual females returned in later seasons to mate with the same male as previously rather than at the same site. Previous work found that male interactions and dominance do not control matings and that females are very choosy about which territory they mate in. Here we show that this is because of the male occupying the territory rather than its position. We therefore conclude that direct female mate choice is the main behavioral process affecting variation in mating success among great snipe males, unlike in some lekking mammals where male competition and/or indirect mate choice appears more important.     

Strain variation, based on the hemagglutinin gene, in Norwegian ISA virus isolates collected from 1987 to 2001: indications of recombination.

Infectious salmon anemia (ISA) is caused by a virus that probably belongs to the Orthomyxoviridae and was first recorded in Norway in 1984. The disease has since spread along the Norwegian coast and has later been found in Canada, Scotland, the Faroe Islands, Chile, and the USA. This study presents sequence variation of the hemagglutinin gene from 37 ISA virus isolates, viz. one isolate from Scotland, one from Canada and 35 from Norway. The hemagglutinin gene contains a highly polymorphic region (HPR), which together with the rest of the gene sequence provides a good tool for studies of epizootics. The gene shows temporal and geographical sequence variation, where certain areas are dominated by distinct groups of isolates. Evidence of transmission of ISA virus isolates within and between regions is given. It is suggested that the hemagglutinin gene from different isolates may recombine. Possible recombination sites are found within the HPR and in the 5'-end flanking region close to the HPR.     

Correlates of male mating success in the lekking great snipe (Gallinago media): results from a four-year study

To investigate behavioral or morphological traits importantas mate choice cues, we measured selection differentials (s)as the covariances between each trait and male mating success,and directional selection gradients (J3) from multiple linearregression of the standardized traits on male mating success.Data from two leks in four consecutive years were included,and the annual data were analyzed separately. The main findingsare: (1) the distribution of male mating success proved to beless skewed than those found in many other lekking species,(2) only a few traits yielded significant selection gradients,(3) the importance of age on male mating success changed acrossyears, (4) females may use traits with a high variance as matechoice cues, and (5) individual males achieved similar matingsuccesses between years. Attendance and age were the traitsmost consistently correlated with male mating success, but notraits showed significant selection gradients in all years.Our results indicate that variable sexual selection pressuresexisted between years, but the high correlation found betweenthe mating success of individual males in successive seasonsalso indicates that permanent differences in male traits areimportant. Key words: lek, mate choice, sexual selection.     

Biological and environmental monitoring of occupational exposure to cyclophosphamide in industry and hospitals

The aims of the study were to clarify potential exposure situations to anticancer agents during industrial processing, drug manufacture and hospital administration, using cyclophosphamide (CP) as the model compound. CP is considered an animal and human carcinogen, and it is shown to be an indirect mutagen in various test systems using several genetic endpoints. Environmental monitoring was performed by collecting ambient air samples during the different processing and handling stages. Both stationary and personal sampling was used. CP was analyzed by liquid chromatography (HPLC) and mass spectrometry (MS). The process materials and intermediates were also analyzed for genotoxic activity using the Ames test and SCE induction in CHO cells as endpoints. Biological monitoring studies were performed on 147 persons representing 5 groups of workers, control subjects and patients. In the experimental part of the project, the intermediates in the CP manufacturing process, CP I (nor-nitrogen mustard) and CP II (phosphoroxydichloride mustard) were found directly active in the 2 genotoxicity tests. These findings led to improvements in work hygiene when handling CP I and CP II in the process. The CP measurements showed that the highest potential-exposure sites occurred during specific operations of the process, e.g., during emptying of the drying drum and during tablet mass preparation (the range of CP concentrations in air was 0.16-0.49 mg/m3). The correlation between indirect genotoxicity and chemical analyses of the ambient air samples was good, revealing the activity to be due to cyclophosphamide. However, the air samples were found mutagenic without metabolic activation also in the beginning of the process; this is obviously due to CP II particles in the ambient air, since no CP was detected chemically. The personal protection of workers in the plant collaborating in the study is efficient and the production unit is equipped with the best available techniques to protect both the personnel and the quality of the drug. Both the urine mutagenicity analyses using strain TA1535 of Salmonella typhimurium as indicator and the cytogenetic analyses of peripheral blood lymphocytes using sister-chromatid exchanges or structural chromosomal aberrations as endpoints were negative. However, a statistically nonsignificant trend in increased number of micronuclei was observed in binucleated lymphocytes of the worker groups as compared with controls. The studies on the hospital use of CP were performed in 3 oncological units and 1 pharmacy unit.(ABSTRACT TRUNCATED AT 400 WORDS)     

Effects of type beta transforming growth factor in combination with retinoic acid or tumor necrosis factor on proliferation of a human glioblastoma cell line and clonogenic cells from freshly resected human brain tumors

Summary Type beta transforming growth factor (-TGF) is a potent regulator of cell growth and differentiation. The human glioblastoma cell line, T-MGl, was growth inhibited by -TGF under anchorage independent conditions. The antiproliferative effect of -TGF was potentiated to nearly total arrest by low doses of retinoic acid (RA) or tumor necrosis factor (TNF), while epidermal growth factor, platelet-derived growth factor, interleukin-2, and gamma interferon did not have this potentiating effect. The potentiation of the -TGF effect by RA and TNF could not be explained by modulation of the epidermal growth factor receptor, the -TGF receptor, or the TNF receptor. -TGF alone and in combination with RA or TNF were further tested on primary cultures from freshly resected human glioma biopsies (n=13). There was great individual variation in sensitivity to -TGF, RA, or TNF. The astrocytoma and oligodendroglioma cells were inhibited to various degrees by -TGF or TNF, while most of the glioblastomas were not sensitive to these agents. Most of the biopsies were stimulated by RA. RA or TNF did not potentiate the growth inhibitory effect of -TGF on biopsy cells. We therefore think it unlikely that -TGF in combination with RA or TNF will be effective agents in the treatment of gliomas.     

An LC–MS-based lipidomics approach for studying the impact of dietary eicosapentaenoic acid on modulating methylmercury toxicity in mice

Introduction

Methylmercury (MeHg) exposure has been a public health problem for many decades. There is a growing interest in searching for possible dietary nutrients that may affect MeHg toxicity.

Objectives

The study aims to evaluate the impact of eicosapentaenoic acid (EPA) on modulating MeHg toxicity in mice.

Methods

The study was based on a two-level factorial design, where the factors were presence or absence of EPA and MeHg in the feed. A liquid chromatography-mass spectrometry-based lipidomics approach was used to identify and quantify the main phospholipid species in mouse liver and plasma. The effects of EPA and MeHg on phospholipid species were evaluated by principal component analysis and statistics. Some biochemical and toxicological markers were measured and hepatic histological assay was carried out.

Results

EPA treatment significantly elevated the phosphatidylcholine (PtdCho) and phosphatidylethanolamine (PtdEtn) species that contain n-3 PUFA, and reduced the levels of PtdCho and PtdEtn species that contain arachidonic acid (ARA), while MeHg exhibited opposite effects on these specific PtdCho species in liver. MeHg induced higher prostaglandin E₂ and lower prostaglandin E₃, thus increasing pro-inflammatory factors, while EPA decreased these ARA-derived inflammatory factors. Moreover, MeHg induced chronic inflammatory symptoms in mice, including severe hepatic necrosis, higher aspartate aminotransferase and alanine aminotransferase activities in plasma, higher thiobarbituric acid reactive substances and lower glutathione in liver. These symptoms were all alleviated by EPA treatment.

Conclusion

EPA may have protective effect against MeHg-induced toxicity due to the favorable modification of membrane phospholipid composition and inhibition of inflammatory factors.

     

Serum fatty acid and lipoprotein subclass concentrations and their associations in prepubertal healthy Norwegian children

Introduction

The lipid metabolism is one of the most important and complex processes in the body. Serum concentrations of 18 fatty acids (FAs) and 24 lipoprotein features, i.e. concentrations of lipoprotein main and subclasses and average particle size in main classes, in 195 ethnic Norwegian children from the rural Fjord region were quantified by chromatography.

Objectives

To assess gender differences in prepubertal children and reveal predictive FA patterns for lipoprotein features.

Methods

Lipoprotein features were modelled from FA profiles using multivariate regression.

Results

Contrary to observations for adults from the same region, gender differences in prepubertal children were generally small. However, higher concentrations of C16–C18 FAs for girls compared to boys correlated to higher concentrations of triglycerides (TG) and very low density lipoprotein (VLDL) particles and larger average size of VLDL particles. Concentrations of high density lipoprotein (HDL) and its subclass of medium particle size were higher in boys than in girls. These findings are opposite to observations in adults from the same region, but reflect that prepubertal boys are more physically active than girls. Furthermore, children possessed only half the serum levels of eicosapentaenoic acid and docosahexaenoic acid measured in adults. Since sampling was done after 12 h of fasting, these differences may reflect higher rate of utilization of these crucial FAs in children.

Conclusion

Good predictive models were obtained for TGs, VLDL and chylomicrons with C14–C18 FAs as major contributors. Weak predictive associations were observed for HDL and Apolipoprotein A1 (ApoA1) with C20–C24 FAs as contributors.