Mitochondrial toxicity detected in a health product with a boar spermatozoan bioassay

Seaweed and organic alfalfa capsules sold as "health promoting" products had repeatedly caused emesis in a consumer. Using the boar spermatozoan bioassay, the capsule contents were found to contain a toxic substance that inhibited boar sperm motility and depolarised mitochondria at low exposure concentrations of 10 microg/ml. The capsule also contained high amounts (10(5)-10(7) cfu/g), of endospore-forming bacteria and Streptomyces-like bacteria. Bacteria from the capsule produced toxic substances when cultured in the laboratory. Three different toxic responses were provoked in the spermatozoa exposed to extracts from the Streptomyces-like isolates: a) hyperpolarisation of the plasma membrane and depolarisation of the mitochondria; b) depolarisation of mitochondria similar to that caused by the capsule content extract; and c) motility inhibition, with no observed change of any cytosolic transmembrane potential. Membrane potential changes in the sperm cells exposed to the bacterial extracts were similar to those provoked by exposure to valinomycin and bafilomycin A1, to nigericin, and to oligomycin and ionomycin, respectively. Extracts prepared from Bacillus isolated from the capsule non-specifically depolarised all the cellular transmembrane potentials. The results demonstrate the potential value of a cell toxicity assay with boar spermatozoa for detecting hazardous substances in products intended for human consumption, without whole-animal exposure or using fetal calf serum for cell cultures.     

Prevention of flower development in birch and other plants using a BpFULL1::BARNASE construct

The prevention of flower formation is important for avoiding the spread of transgenes from genetically modified plants into wild populations. Moreover, the resources not expended for the generation of flowers and fruits might be allocated to increased vegetative growth. We have been developing methods for preventing flower formation in silver birch (Betula pendula), a tree species of considerable economical importance in the boreal region. Here we study the suitability of the promoter of BpFRUITFULL-LIKE1 (BpFULL1, formerly BpMADS5) for tissue-specific ablation of inflorescences in Arabidopsis, tobacco and birch. With all these species, the development of inflorescences was successfully prevented. The results show that the BpFULL1::BARNASE construct has potential biotechnological applications in different plant species.This revised version was published online in March 2005 because the name of the second author (M. Hassinen) was missing.     

Decomposition of cellulose strips in relation to climate,litterfall nitrogen,phosphorus and C/N ratio in natural boreal forests

Isolates of Alternaria alternata, Botrytis cinerea, Fusarium oxysporum, Penicillium sp., Rhizoctonia solani, Stemphylium sp., Thielaviopsis basicola, and Verticillium dahliae were cultured on potato–dextrose agar (PDA), barley-sand and alfalfa-sand substrates in petri-dish or in column microcosms. N-mineralization by fungi and fungal-feeding nematodes in combination or fungi alone was assessed. Numbers of Aphelenchus avenae or Aphelenchoides composticola supported by the fungi were measured every 7 days. Times for full colonization of the substrates by fungi ranged from 5 to 15 days. Rhizoctonia solani and B. cinerea on PDA supported the largest A. avenae and A. composticola populations, respectively. Penicillium sp. was a nonhost for A. composticola and A. avenae. Rhizoctonia solani, B. cinerea, V. dahliae, and F. oxysporum supported significantly more nematodes than the other four fungal species. The ranked order of fungi based on the amount of N mineralized in columns free of nematodes was A. alternata (with a rate of 0.052 μg N/g-sand per day), Stemphylium sp., V. dahliae, T. basicola, B. cinerea, F. oxysporum, R. solani, and Penicillium sp. (with a rate of 0.0045 μg N/g-sand perday). The presence of A. avenae resulted in significant increases in mineral N, compared to nematode-free columns colonized by F. oxysporum, R. solani, and T. basicola alone. The presence of A. composticola resulted in significant increases in mineral N, compared to nematode-free columns colonized by A. alternata, B. cinerea, F. oxysporum, and R. solani alone. There was more mineral N incolumns in the presence of A. composticola than A. avenae in most cases. This revised version was published online in August 2006 with corrections to the Cover Date.     

Income and Physical Activity among Adults: Evidence from Self-Reported and Pedometer-Based Physical Activity Measurements

This study examined the relationship between income and physical activity by using three measures to illustrate daily physical activity: the self-reported physical activity index for leisure-time physical activity, pedometer-based total steps for overall daily physical activity, and pedometer-based aerobic steps that reflect continuous steps for more than 10 min at a time. The study population consisted of 753 adults from Finland (mean age 41.7 years; 64% women) who participated in 2011 in the follow-up of the ongoing Young Finns study. Ordinary least squares models were used to evaluate the associations between income and physical activity. The consistency of the results was explored by using register-based income information from Statistics Finland, employing the instrumental variable approach, and dividing the pedometer-based physical activity according to weekdays and weekend days. The results indicated that higher income was associated with higher self-reported physical activity for both genders. The results were robust to the inclusion of the control variables and the use of register-based income information. However, the pedometer-based results were gender-specific and depended on the measurement day (weekday vs. weekend day). In more detail, the association was positive for women and negative or non-existing for men. According to the measurement day, among women, income was positively associated with aerobic steps despite the measurement day and with totals steps measured on the weekend. Among men, income was negatively associated with aerobic steps measured on weekdays. The results indicate that there is an association between income and physical activity, but the association is gender-specific and depends on the measurement type of physical activity.     

Phosphorus chemistry and bacterial community composition interact in brackish sediments receiving agricultural discharges

Background

External nutrient discharges have caused eutrophication in many estuaries and coastal seas such as the Baltic Sea. The sedimented nutrients can affect bacterial communities which, in turn, are widely believed to contribute to release of nutrients such as phosphorus from the sediment.

Methods

We investigated relationships between bacterial communities and chemical forms of phosphorus as well as elements involved in its cycling in brackish sediments using up-to-date multivariate statistical methods. Bacterial community composition was determined by terminal restriction fragment length polymorphism and cloning of the 16S rRNA gene.

Results and Conclusions

The bacterial community composition differed along gradients of nutrients, especially of different phosphorus forms, from the estuary receiving agricultural phosphorus loading to the open sea. This suggests that the chemical composition of sediment phosphorus, which has been affected by riverine phosphorus loading, influenced on bacterial communities. Chemical and spatial parameters explained 25% and 11% of the variation in bacterial communities. Deltaproteobacteria, presumptively sulphate and sulphur/iron reducing, were strongly associated to chemical parameters, also when spatial autocorrelation was taken into account. Sulphate reducers correlated positively with labile organic phosphorus and total nitrogen in the open sea sediments. Sulphur/iron reducers and sulphate reducers linked to iron reduction correlated positively with aluminium- and iron-bound phosphorus, and total iron in the estuary. The sulphate and sulphur/iron reducing bacteria can thus have an important role both in the mineralization and mobilization of nutrients from sediment.

Significance

Novelty in our study is that relationships between bacterial community composition and different phosphorus forms, instead of total phosphorus, were investigated. Total phosphorus does not necessarily bring out interactions between bacteria and phosphorus chemistry since proportions of easily usable mobile (reactive) phosphorus and immobile phosphorus forms in different sediments can vary. Our study suggested possible feedbacks between different forms of phosphorus and bacterial community composition.     

Potato Crop as a Source of Emetic Bacillus cereus and Cereulide-Induced Mammalian Cell Toxicity

Bacillus cereus, aseptically isolated from potato tubers, were screened for cereulide production and for toxicity on human and other mammalian cells. The cereulide-producing isolates grew slowly, the colonies remained small (∼1 mm), tested negative for starch hydrolysis, and varied in productivity from 1 to 100 ng of cereulide mg (wet weight)⁻¹ (∼0.01 to 1 ng per 10⁵ CFU). By DNA-fingerprint analysis, the isolates matched B. cereus F5881/94, connected to human food-borne illness, but were distinct from cereulide-producing endophytes of spruce tree (Picea abies). Exposure to cell extracts (1 to 10 μg of bacterial biomass ml⁻¹) and to purified cereulide (0.4 to 7 ng ml⁻¹) from the potato isolates caused mitochondrial depolarization (loss of ΔΨm) in human peripheral blood mononuclear cells (PBMC) and keratinocytes (HaCaT), porcine spermatozoa and kidney tubular epithelial cells (PK-15), murine fibroblasts (L-929), and pancreatic insulin-producing cells (MIN-6). Cereulide (10 to 20 ng ml⁻¹) exposed pancreatic islets (MIN-6) disintegrated into small pyknotic cells, followed by necrotic death. Necrotic death in other test cells was observed only after a 2-log-higher exposure. Exposure to 30 to 60 ng of cereulide ml⁻¹ induced K⁺ translocation in intact, live PBMC, keratinocytes, and sperm cells within seconds of exposure, depleting 2 to 10% of the cellular K⁺ stores within 10 min. The ability of cereulide to transfer K⁺ ions across biological membranes may benefit the producer bacterium in K⁺-deficient environments such as extracellular spaces inside plant tissue but is a pathogenic trait when in contact with mammalian cells.     

Chlamydia trachomatis Infection Induces Replication of Latent HHV-6

Human herpesvirus-6 (HHV-6) exists in latent form either as a nuclear episome or integrated into human chromosomes in more than 90% of healthy individuals without causing clinical symptoms. Immunosuppression and stress conditions can reactivate HHV-6 replication, associated with clinical complications and even death. We have previously shown that co-infection of Chlamydia trachomatis and HHV-6 promotes chlamydial persistence and increases viral uptake in an in vitro cell culture model. Here we investigated C. trachomatis-induced HHV-6 activation in cell lines and fresh blood samples from patients having Chromosomally integrated HHV-6 (CiHHV-6). We observed activation of latent HHV-6 DNA replication in CiHHV-6 cell lines and fresh blood cells without formation of viral particles. Interestingly, we detected HHV-6 DNA in blood as well as cervical swabs from C. trachomatis-infected women. Low virus titers correlated with high C. trachomatis load and vice versa, demonstrating a potentially significant interaction of these pathogens in blood cells and in the cervix of infected patients. Our data suggest a thus far underestimated interference of HHV-6 and C. trachomatis with a likely impact on the disease outcome as consequence of co-infection.     

Effects of insulin therapy on liver fat content and hepatic insulin sensitivity in patients with type 2 diabetes

We determined whether insulin therapy changes liver fat content (LFAT) or hepatic insulin sensitivity in type 2 diabetes. Fourteen patients with type 2 diabetes (age 51+/-2 yr, body mass index 33.1+/-1.4 kg/m2) treated with metformin alone received additional basal insulin for 7 mo. Liver fat (proton magnetic resonance spectroscopy), fat distribution (MRI), fat-free and fat mass, and whole body and hepatic insulin sensitivity (6-h euglycemic hyperinsulinemic clamp combined with infusion of [3-(3)H]glucose) were measured. The insulin dose averaged 75+/-10 IU/day (0.69+/-0.08 IU/kg, range 24-132 IU/day). Glycosylated hemoglobin A1c (Hb A1c) decreased from 8.9+/-0.3 to 7.4+/-0.2% (P<0.001). Whole body insulin sensitivity increased from 2.21+/-0.38 to 3.08+/-0.40 mg/kg fat-free mass (FFM).min (P<0.05). This improvement could be attributed to enhanced suppression of hepatic glucose production (HGP) by insulin (HGP 1.04+/-0.28 vs. 0.21+/-0.19 mg/kg FFM.min, P<0.01). The percent suppression of HGP by insulin increased from 72+/-8 to 105+/-11% (P<0.01). LFAT decreased from 17+/-3 to 14+/-3% (P<0.05). The change in LFAT was significantly correlated with that in hepatic insulin sensitivity (r=0.56, P<0.05). Body weight increased by 3.0+/-1.1 kg (P<0.05). Of this, 83% was due to an increase in fat-free mass (P<0.01). Fat distribution and serum adiponectin concentrations remained unchanged while serum free fatty acids decreased significantly. Conclusions: insulin therapy improves hepatic insulin sensitivity and slightly but significantly reduces liver fat content, independent of serum adiponectin.