Oligotrophication as a result of planktivorous fish removal with rotenone in the small,eutrophic, Lake Mosvatn,Norway

In September 1987 the shallow, eutrophic, Lake Mosvatn was treated with rotenone to eliminate planktivorous fish (mainly whitefish,Coregonus lavaretus, L.), and the effects were studied. The first summer after treatment the zooplankton community changed markedly from rotifer dominance and few grazers, to a community with few rotifers and many grazers. Accordingly there was a fivefold increase in the biomass ofDaphnia galeata. Adult females ofD. galeata approximately doubled in weight. The decrease in rotifer biomass was probably mainly due to a loss of food by competition with the daphnids. The phytoplankton community was also markedly affected. Prior to treatment Secchi depth was 1.7 m and Chl-a 23μg l⁻¹ in the summer. After treatment there was an increase in the proportion of small and gelatinous algae and the mean chlorophyll concentration fell to 7μg Chl-a l⁻¹. Secchi depth increased to>2.3 m (bottom-sight most of the season). After the treatment there were also fewer cyanobacterial blooms. This seems to be related to oligotrophication caused indirectly by increased grazing by the zooplankton. Total nutrient concentrations were affected. Prior to treatment the mean summer concentration of total phosphate was 44μg P l⁻¹. This decreased to 29μg P l⁻¹ in the first summer and 23μg P l⁻¹ the second summer after the treatment. Total nitrogen decreased from 0.68 mg N l⁻¹ before treatment to 0.32 mg N l⁻¹ the first summer after the treatment. The phosphate loading was not reduced, therefor it can be concluded that the fish removal provided a biomanipulation which caused the more oligotrophic conditions.     

Spruce sugars and poultry hydrolysate as growth medium in repeated fed-batch fermentation processes for production of yeast biomass

Bioprocess and Biosystems Engineering - The production of microbial protein in the form of yeast grown on lignocellulosic sugars and nitrogen-rich industrial residues is an attractive approach for...     

An assessment of swinger techniques for the playground swing oscillatory motion

Much attention has been devoted to how playground swing amplitudes are built up by swinger techniques, i.e. body actions. However, very little attention has been given to the requirements that such swinger techniques place on the swinger himself. The purpose of this study was to find out whether different swinger techniques yield significantly different maximum torques, endurance and coordinative skills, and also to identify preferable techniques. We modelled the seated swinger as a rigid dumbbell and compared three different techniques. A series of computer simulations were run with each technique, testing the performance with different body rotational speeds, delayed onset of body rotation and different body mass distributions, as swing amplitudes were brought up towards 90°. One technique was found to be extremely sensitive to the timing of body actions, limiting swing amplitudes to 50° and 8° when body action was delayed by 0.03 and 0.3 s, respectively. Two other more robust techniques reached 90° even with the largest of these delays, although more time (and endurance) was needed. However, these two methods also differed with respect to maximum torque and endurance, and none was preferable in both these aspects, being dependent on the swinger goals and abilities.     

S. haematobium as a Common Cause of Genital Morbidity in Girls: A Cross-sectional Study of Children in South Africa

Background

Schistosoma (S.) haematobium infection is a common cause of genital morbidity in adult women. Ova in the genital mucosal lining may cause lesions, bleeding, pain, discharge, and the damaged surfaces may pose a risk for HIV. In a heterogeneous schistosomiasis endemic area in South Africa, we sought to investigate if young girls had genital symptoms and if this was associated with urinary S. haematobium.

Methodology

In a cross-sectional study of 18 randomly chosen primary schools, we included 1057 schoolgirls between the age of 10 and 12 years. We interviewed assenting girls, whose parents had consented to their participation and examined three urines from each of them for schistosome ova.

Principal findings

One third of the girls reported to have a history of genital symptoms. Prior schistosomal infection was reported by 22% (226/1020), this was associated with current genital symptoms (p<0.001). In regression analysis the genital symptoms were significantly associated both with urinary schistosomiasis (p<0.001) and water contact (p<0.001).

Conclusions

Even before sexually active age, a relatively large proportion of the participating girls had similar genital symptoms to those reported for adult genital schistosomiasis previously. Anti-schistosomal treatment should be considered at a young age in order to prevent chronic genital damage and secondary infections such as HIV, sexually transmitted diseases and other super-infections.     

Investigating alginate production and carbon utilization in Pseudomonas fluorescens SBW25 using mass spectrometry-based metabolic profiling

Metabolic profiling of Pseudomonas fluorescens SBW25 and various mutants derived thereof was performed to explore how the bacterium adapt to changes in carbon source and upon induction of alginate synthesis. The experiments were performed at steady-state conditions in nitrogen-limited chemostats using either fructose or glycerol as carbon source. Carbon source consumption was up-regulated in the alginate producing mutant with inactivated anti-sigma factor MucA. The mucA- mutants (also non-alginate producing mucA- control strains) had a higher dry weight yield on carbon source implying a change in carbon and energy metabolism due to the inactivation of the anti-sigma factor MucA. Both LC–MS/MS and GC–MS methods were used for quantitative metabolic profiling, and major reorganization of primary metabolite pools in both an alginate producing and a carbon source dependent manner was observed. Generally, larger changes were observed among the phosphorylated glycolytic metabolites, the pentose phosphate pathway metabolites and the nucleotide pool than among amino acids and citric acid cycle compounds. The most significant observation at the metabolite level was the significantly reduced energy charge of the mucA- mutants (both alginate producing and non-producing control strains) compared to the wild type strain. This reduction was caused more by a strong increase in the AMP pool than changes in the ATP and ADP pools. The alginate-producing mucA- mutant had a slightly increased GTP pool, while the GDP and GMP pools were strongly increased compared to non-producing mucA- strains and to the wild type. Thus, whilst changes in the adenosine phosphate nucleotide pool are attributed to the mucA inactivation, adjustments in the guanosine phosphate nucleotide pool are consequences of the GTP-dependent alginate production induced by the mucA inactivation. This metabolic profiling study provides new insight into carbon and energy metabolism of the alginate producer P. fluorescens.     

CREB3L1 Is a Metastasis Suppressor That Represses Expression of Genes Regulating Metastasis,Invasion, and Angiogenesis

The unfolded protein response (UPR) is activated in response to hypoxia-induced stress such as in the tumor microenvironment. This study examined the role of CREB3L1 (cyclic AMP [cAMP]-responsive element-binding protein 3-like protein 1), a member of the UPR, in breast cancer development and metastasis. Initial experiments identified the loss of CREB3L1 expression in metastatic breast cancer cell lines compared to low-metastasis or nonmetastatic cell lines. When metastatic cells were transfected with CREB3L1, they demonstrated reduced invasion and migration in vitro, as well as a significantly decreased ability to survive under nonadherent or hypoxic conditions. Interestingly, in an in vivo rat mammary tumor model, not only did CREB3L1-expressing cells fail to form metastases compared to CREB3L1 null cells but regression of the primary tumors was seen in 70% of the animals as a result of impaired angiogenesis. Microarray and chromatin immunoprecipitation with microarray technology (ChIP on Chip) analyses identified changes in the expression of many genes involved in cancer development and metastasis, including a decrease in those involved in angiogenesis. These data suggest that CREB3L1 plays an important role in suppressing tumorigenesis and that loss of expression is required for the development of a metastatic phenotype.     

Fatal inanition in reindeer (<Emphasis Type="Italic">Rangifer tarandus tarandus</Emphasis>): Pathological findings in completely emaciated carcasses

Background  

In a project to determine the causes of winter mortality in reindeer in Finnmark County, northern Norway, the most frequent diagnosis turned out to be complete emaciation, despite several of the reindeer having been given silage for up to 4 weeks before they died. The present paper describes autopsy results and other findings in these animals.     

Methylpurine DNA glycosylase of the hyperthermophilic archaeon Archaeoglobus fulgidus

Base excision repair of DNA alkylation damage is initiated by a methylpurine DNA glycosylase (MPG) function. Such enzymes have previously been characterized from bacteria and eukarya, but not from archaea. We identified activity for the release of methylated bases from DNA in cell-free extracts of Archaeoglobus fulgidus, an archaeon growing optimally at 83 degrees C. An open reading frame homologous to the alkA gene of Escherichia coli was overexpressed and identified as a gene encoding an MPG enzyme (M(r) = 34 251), hereafter designated afalkA. The purified AfalkA protein differs from E. coli AlkA by excising alkylated bases only, from DNA, in the following order of efficiency: 3-methyladenine (m(3)A) > 3-methylguanine approximately 7-methyladenine > 7-methylguanine. Although the rate of enzymatic release of m(3)A is highest in the temperature range of 65-75 degrees C, it is only reduced by 50% at 45 degrees C, a temperature that does not support growth of A. fulgidus. At temperatures above 75 degrees C, nonenzymatic release of methylpurines predominates. The results suggest that the biological function of AfalkA is to excise m(3)A from DNA at suboptimal and maybe even mesophilic temperatures. This hypothesis is further supported by the observation that the afalkA gene function suppresses the alkylation sensitivity of the E. coli tag alkA double mutant. The amino acid sequence similarity and evolutionary relationship of AfalkA with other MPG enzymes from the three domains of life are described and discussed.