Oestradiol potentiates the effects of certain pyrethroid compounds in the MCF7 human breast carcinoma cell line

Pyrethroids are the most widely used insecticides for indoor pest control, so human exposure to them is common. The main target of pyrethroids is the nervous system, but their endocrine disrupting capabilities may also be of toxicological concern. In the present study, the proliferation of the breast cancer cell line, MCF7, was studied after a 7-day exposure to various concentrations of pyrethrin, permethrin and cypermethrin. The effects of oestradiol and the combined effects of oestradiol (0.10 nM) and pyrethroids (0.1-100 microM) on MCF7 cell proliferation were also evaluated. Proliferation and cell toxicity were studied by measuring the ATP content with a luminescence method, and mitochondrial metabolic enzyme activity with the WST-1 test. In the ATP test, low concentrations (0.1-1 microM) of pyrethroids in co-exposure with oestradiol caused a clear statistically significant increase in the proliferation of MCF7 cells. This was evident when compared to the proliferative effect caused by 0.1 nM oestradiol alone. High concentrations were cytotoxic, and the greatest cell toxicity was that of cypermethrin, which has a cyano group in its molecular structure.     

Trichoderma reesei sequences that bind to the nuclear matrix enhance transformation frequency

Three DNA fragments, trs1, 2 and 3, were isolated from the Trichoderma reesei genome on the basis of their ability to promote autonomous replication of plasmids in Saccharomyces cerevisiae. Each trs element bound specifically to the isolated T. reesei nuclear matrix in vitro, and two of them bound in vivo, indicating that they are matrix attachment regions (MARs). A similar sequence previously isolated from Aspergillus nidulans (ans1) was also shown to bind specifically to the T. reesei nuclear matrix in vitro. The T. reesei MARs are AT-rich sequences containing 70%, 86% and 73% A+T over 2.9, 0.8 and 3.7?kb, respectively for trs1, 2 and 3. They exhibited no significant sequence homology, but were shown to contain a number of sequence motifs that occur frequently in many MARs identified in other eukaryotes. However, these motifs occurred as frequently in the trs elements as in randomly generated sequences with the same A+T content. trs1 and 3 were shown to be present as single copies in the T. reesei genome. The presence of the trs elements in transforming plasmids enhanced the frequency of integrative transformation of T. reesei up to five fold over plasmids without a trs. No evidence was obtained to suggest that the trs elements promoted efficient replication of plasmids in T. reseei. A mechanism for the enhancement of transformation frequency by the trs elements is proposed.     

Predator–rodent–plant interactions along a coast–inland gradient in Fennoscandian tundra

Spatial variation in the strength of trophic cascades in arctic tundra has been related to flows of subsidies across ecosystem boundaries. Here, we ask whether the input of marine subsidies in tundra systems would cause spatial variation in the strength of rodent–plant interactions between coastal areas, where predators have access to marine‐derived resources, and non‐subsidized inland areas of northern Fennoscandia. We present a detailed evaluation of predator–rodent–vegetation interactions along a coast‐inland gradient, during the 2011 rodent outbreak and the two following decline years, by using direct assessments of rodent impacts and tracing of marine‐derived nutrients in the food web. Our results revealed that the main rodent predator during summer, the long‐tailed jaeger Stercorarius longicaudus, did not benefit from marine resources while breeding (relative dietary proportion in chicks’ diet = 0–3%). Contrary to this pattern, parasitic jaegers S. parasiticus, bred exclusively near the coast and preyed effectively on both marine resources (41% of chicks’ diet) and rodents (12%). Mammalian predators also showed a higher activity during winter near the coast. Despite overall higher predator numbers, no evidence was found for lower rodent population growth rates during the three monitoring summers and for weaker rodent grazing impacts in the coastal area. Instead, we documented pronounced damages caused by lemmings and voles on bryophytes and vascular plants, especially dwarf shrubs (e.g. Vaccinum myrtillus) all along the coast–inland gradient. Taken together, our results did not support the hypothesis that marine subsidies would trigger a trophic cascade in coastal tundra areas of northern Fennoscandia during a major rodent outbreak, probably due to a relatively low diversity of marine‐subsidized predators in the region. Comparative observational and experimental studies at large spatial scales in various arctic regions are absolutely necessary for a better understanding of factors causing regional variations in the functioning of arctic food webs.     

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.

     

Within-stand variation in silver birch (Betula pendula Roth) phenology

Key message

Within a local population genotypes differ in the timing of bud burst, but genotypes with early bud burst unfold their leaves slower, resulting in an equal period of carbon gain.

Abstract

The ability of local populations to cope with disturbances like adverse weather events or a changing climate depends on the genotypic richness of such populations, emphasising the importance of differences between genotypes in traits related to growth and survival at this scale. Due to their longevity, these differences are of special importance in trees, yet for trees, differences between genotypes within local populations remain unexplored. The phenological cycle is important in this respect, since a correct timing of phenological events is critical for growth and survival of trees, especially in environments with strong seasonality and changes in the timing of phenological events has consequences for, among others, net ecosystem productivity and the climate system as a whole. In this light accounting for differences in the timing of phenological events within species is currently identified as a research challenge. This study contributes to the knowledge of differences between genotypes on the small spatial scale of a local population. We examined the timing of phenological events of 15 micropropagated silver birch (Betula pendula Roth) genotypes representing a natural population. Measurements covered bud burst (7 years) and leaf unfolding in spring and chlorophyll degradation in autumn (2 years for both). These data were used to estimate the period of carbon gain. Differences between genotypes in the temperature sum required for bud burst were present, with genotypes showing ‘early’ (i.e. a low temperature sum requirement for bud burst) and ‘late’ bud burst across the 7-year study period. Differences were small in most years (i.e. 3 days), but differences of 16 days were recorded within the 7-year study period as well. Genotypes with ‘early’ bud burst were less sensitive to variations in environmental conditions in spring compared to genotypes with ‘late’ bud burst. Differences in bud burst were not carried over to the estimated period of carbon gain. Due to faster leaf expansion in genotypes with ‘late’ bud burst and the lack of differences between genotypes in autumn senescence the estimated period of carbon gain was similar among genotypes.     

Postural control and thigh muscle activity in men with knee osteoarthritis

The aim of this study was to examine the standing balance and the function of vastus medialis (VM) and biceps femoris (BF) muscles with surface electromyography (EMG). Fifty-four subjects with uni- or bilateral knee osteoarthritis (OA) (aged 50–69 years) and 53 age-matched randomly selected clinically and radiologically healthy men participated in this study. Postural control was assessed on a force platform with a bipedal stance with eyes open (EO) and closed (EC) and a monopedal stance with EO. The balance parameters, mean sway velocity, velocity along AP and ML axes, elliptical area, standard deviation of center of pressure, average radial displacement, mean frequency and frequency domain balance parameters and different power spectral density frequency bands were determined. Root mean square (RMS) for EMG amplitude, mean EMG frequency (f_EMG,mean) and median EMG frequency (f_EMG,med) of motor unit activity were calculated from the normalized EMG data. During bipedal stance with EC and EO, there were no significant differences in balance parameters between groups, but during bipedal stance with EO, the RMS in VM was about 56% higher (p < 0.05) in subjects with knee OA than in the control subjects and the values of f_EMG,mean and f_EMG,med were about 48% higher (p < 0.05) in control subjects than subjects with knee OA. It is concluded that subjects with knee OA do not have any standing balance deficit, but they do exhibit increased muscle activity in VM muscle compared to control subjects.     

Two-locus genome-wide linkage scan for prostate cancer susceptibility genes with an interaction effect

Prostate cancer represents a significant worldwide public health burden. Epidemiological and genetic epidemiological studies have consistently provided data supporting the existence of inherited prostate cancer susceptibility genes. Segregation analyses of prostate cancer suggest that a multigene model may best explain familial clustering of this disease. Therefore, modeling gene–gene interactions in linkage analysis may improve the power to detect chromosomal regions harboring these disease susceptibility genes. In this study, we systematically screened for prostate cancer linkage by modeling two-locus gene–gene interactions for all possible pairs of loci across the genome in 426 prostate cancer families from Johns Hopkins Hospital, University of Michigan, University of Umeå, and University of Tampere. We found suggestive evidence for an epistatic interaction for six sets of loci (target chromosome-wide/reference marker-specific P≤0.0001). Evidence for these interactions was found in two independent subsets from within the 426 families. While the validity of these results requires confirmation from independent studies and the identification of the specific genes underlying this linkage evidence, our approach of systematically assessing gene–gene interactions across the entire genome represents a promising alternative approach for gene identification for prostate cancer.     

Effect of thawing time, cooling rate and boron nutrition on freezing point of the primordial shoot in norway spruce buds

BACKGROUND: Effects of cooling rates on bud frost hardiness have been studied but there is little information on bud responses to thawing. Since the cell wall pore size has been found to increase with boron (B) deficiency, B deficiency may affect the supercooling ability of buds in winter. METHODS: The effects of duration of thawing time and rate of cooling on bud frost hardiness of Norway spruce (Picea abies) were studied in a B fertilization trial in February 2003 and March 2005. Frost hardiness of apical buds was determined by differential thermal analysis (DTA) and visual scoring of damage. KEY RESULTS: In 2003, the freezing point of primordial shoots of buds (T(f)), i.e. the low-temperature exotherm (LTE), was, on average, -39 degrees C when buds were thawed for less than 3 h and the T(f) increased to -21 degrees C after 18 h of thawing. During the first 4 h of thawing, the rate of dehardening was 6 degrees C h(-1). In 2005, buds dehardened linearly from -39 degrees C to -35 degrees C at a rate of 0.7 degrees C h(-1). In 2003, different cooling rates of 1-5 degrees C h(-1) had a minor effect on T(f) but in 2005 with slow cooling rates T(f) decreased. In both samplings, at cooling rates of 2 and 1 degrees C h(-1), T(f) was slightly higher in B-fertilized than in non-fertilized trees. By contrast, at very short thawing times in 2003, T(f) was somewhat lower in B-fertilized trees. CONCLUSIONS: There was little evidence of reduced frost hardiness in trees with low B status. This study showed that buds deharden rapidly when exposed to above-freezing temperatures in winter, but if cooled again they reharden more slowly. According to this study, rapid dehardening of buds has to be taken into account in assessments of frost hardiness.     

Does ice crystal formation in buds explain growth disturbances in boron-deficient Norway spruce?

Loss of apical dominance in boron-deficient trees has been suggested to be due to frost damage of terminal buds and leaders. Excessive nitrogen (N) supply can exacerbate boron (B) deficiency by the dilution-effect. N may also have direct effects on winter hardiness. We studied frost hardening of buds of Norway spruce (Picea abies L. Karst.) in healthy-looking trees and in trees with growth disturbances. The effect of B and N on frost hardiness was studied in a factorial fertilisation experiment during cold acclimation. Frost hardiness was determined by differential temperature analysis (DTA) and scoring of visual damage. In a DTA profile of apical buds with a piece of stem, low-temperature exotherm (LTE) predicted bud injury, while two of the observed high-temperature exotherms and two of the observed intermediate-temperature exotherms were non injurious. Appearance of LTE followed changes in air temperature. The risk of frost damage was not affected by fertilisation treatments or previously observed growth disturbances. However, when the bud structure was deformed by severe B deficiency, the supercooling ability disappeared. Such buds are probably killed by freezing in nature and therefore, frost damage may play a secondary role in the development of growth disturbances.