Lake-wide assessment of microplastics in the surface waters of Lake Baikal,Siberia

Limnology - Small microplastic particles < 330 µm, sometimes called mini-microplastics (MMP), are far more abundant than those larger than 330 µm....     

Seasonality and resource availability control bacterial and archaeal communities in soils of a temperate beech forest

It was hypothesized that seasonality and resource availability altered through tree girdling were major determinants of the phylogenetic composition of the archaeal and bacterial community in a temperate beech forest soil. During a 2-year field experiment, involving girdling of beech trees to intercept the transfer of easily available carbon (C) from the canopy to roots, members of the dominant phylogenetic microbial phyla residing in top soils under girdled versus untreated control trees were monitored at bimonthly intervals through 16S rRNA gene-based terminal restriction fragment length polymorphism profiling and quantitative PCR analysis. Effects on nitrifying and denitrifying groups were assessed by measuring the abundances of nirS and nosZ genes as well as bacterial and archaeal amoA genes. Seasonal dynamics displayed by key phylogenetic and nitrogen (N) cycling functional groups were found to be tightly coupled with seasonal alterations in labile C and N pools as well as with variation in soil temperature and soil moisture. In particular, archaea and acidobacteria were highly responsive to soil nutritional and soil climatic changes associated with seasonality, indicating their high metabolic versatility and capability to adapt to environmental changes. For these phyla, significant interrelations with soil chemical and microbial process data were found suggesting their potential, but poorly described contribution to nitrification or denitrification in temperate forest soils. In conclusion, our extensive approach allowed us to get novel insights into effects of seasonality and resource availability on the microbial community, in particular on hitherto poorly studied bacterial phyla and functional groups.     

Ethanol and glycerol production under aerobic conditions by wild-type,respiratory-deficient mutants and a fusion product of Saccharomyces cerevisiae

Summary Experiments were performed to investigate growth, ethanol and glycerol production by wild-type strains (RHO) and respiratory-deficient (rho) mutants of Saccharomyces cerevisiae. Furthermore protoplasts were fused in order to enhance the fermentation capacity of a flocculent strain. At high substrate conditions, 150 g/l of saccharose, there is no difference in cell growth. However, at a glucose concentration of 10–20 g/l the mutants grow much slower. After 3 days of incubation at 28° C in a complete medium the viability of the two strains is the same. In minimal medium on the other hand the number of viable cells of the mutant is 100-fold reduced. All mutants tested showed a higher specific activity of alcohol dehydrogenase (ADH I) and an enhanced production of glycerol compared with the wild-type strain. By protoplast fusion a modified flocculent strain was obtained with higher specific activity of ADH I and a reduced biosynthesis of glycerol. However, the yields of ethanol (75–78%) are about the same for the wild-type strain and the rho mutants under aerobic conditions in absence of catabolite repression.     

Genetic variability of proteins from plasma membranes and cytosols of mouse organs

The genetic variability of membrane proteins (structure-bound proteins) and cytosol proteins (water-soluble proteins) was investigated in two inbred strains of the mouse, C57BL/6J and DBA/2J. Membrane proteins and cytosol were isolated from the brain and liver of the mouse. The proteins were separated by two-dimensional electrophoresis. A high number of genetic variant proteins (brain, 30; liver, 72) was found in the cytosol. Most of these variants represented changes in the amount of proteins. Electrophoretic mobility changes occurred only in about 1% (brain, 6; liver, 9) of all protein spots of a two-dimensional pattern. In contrast to the cytosol proteins, no genetic variation was detected among the membrane proteins, not even for the quantitative characteristics of the protein spots. The results obtained for the two classes of proteins suggest that the degree of variability in the amount of proteins is related to the degree of variability in the structure of proteins.     

Placental growth factor contributes to micro-vascular abnormalization and blood-retinal barrier breakdown in diabetic retinopathy

Objective

There are controversies regarding the pro-angiogenic activity of placental growth factor (PGF) in diabetic retinopathy (DR). For a better understanding of its role on the retina, we have evaluated the effect of a sustained PGF over-expression in rat ocular media, using ciliary muscle electrotransfer (ET) of a plasmid encoding rat PGF-1 (pVAX2-rPGF-1).

Materials and Methods

pVAX2-rPGF-1 ET in the ciliary muscle (200 V/cm) was achieved in non diabetic and diabetic rat eyes. Control eyes received saline or naked plasmid ET. Clinical follow up was carried out over three months using slit lamp examination and fluorescein angiography. After the control of rPGF-1 expression, PGF-induced effects on retinal vasculature and on the blood-external barrier were evaluated respectively by lectin and occludin staining on flat-mounts. Ocular structures were visualized through histological analysis.

Results

After fifteen days of rPGF-1 over-expression in normal eyes, tortuous and dilated capillaries were observed. At one month, microaneurysms and moderate vascular sprouts were detected in mid retinal periphery in vivo and on retinal flat-mounts. At later stages, retinal pigmented epithelial cells demonstrated morphological abnormalities and junction ruptures. In diabetic retinas, PGF expression rose between 2 and 5 months, and, one month after ET, rPGF-1 over-expression induced glial activation and proliferation.

Conclusion

This is the first demonstration that sustained intraocular PGF production induces vascular and retinal changes similar to those observed in the early stages of diabetic retinopathy. PGF and its receptor Flt-1 may therefore be looked upon as a potential regulatory target at this stage of the disease.     

The Sub-Cellular Localization of WRAP53 Has Prognostic Impact in Breast Cancer

WRAP53 protein controls intracellular trafficking of DNA repair proteins, the telomerase enzyme, and splicing factors. Functional loss of the protein has been linked to carcinogenesis, premature aging and neurodegeneration. The aim of this study was to investigate the prognostic significance of WRAP53 protein expression in breast cancer. A tissue microarray was constructed from primary breast tumors and immunostained by a polyclonal WRAP53 antibody to assess the protein expression pattern. Two different patient cohorts with long term follow-up were studied; a test- and a validation set of 154 and 668 breast tumor samples respectively. Breast cancer patients with tumor cells lacking the expression of WRAP53 in the nucleus had a significantly poorer outcome compared to patients with tumor cells expressing this protein in the nuclei (HR = 1.95, 95%CI = 1.09–3.51, p = 0.025). Nuclear localization of WRAP53 was further shown to be an independent marker of prognosis in multivariate analysis (HR = 2.57, 95%CI = 1.27–5.19, p = 0.008), and also significantly associated with better outcome in patients with TP53 mutation. Here we show that the sub-cellular localization of the WRAP53 protein has a significant impact on breast cancer survival, and thus has a potential as a clinical marker in diagnostics and treatment.     

Altered expression of the PTR/NRT1 homologue OsPTR9 affects nitrogen utilization efficiency,growth and grain yield in rice

The plant PTR/NRT1 (peptide transporter/nitrate transporter 1) gene family comprises di/tripeptide and low‐affinity nitrate transporters; some members also recognize other substrates such as carboxylates, phytohormones (auxin and abscisic acid), or defence compounds (glucosinolates). Little is known about the members of this gene family in rice (Oryza sativa L.). Here, we report the influence of altered OsPTR9 expression on nitrogen utilization efficiency, growth, and grain yield. OsPTR9 expression is regulated by exogenous nitrogen and by the day‐night cycle. Elevated expression of OsPTR9 in transgenic rice plants resulted in enhanced ammonium uptake, promotion of lateral root formation and increased grain yield. On the other hand, down‐regulation of OsPTR9 in a T‐DNA insertion line (osptr9) and in OsPTR9‐RNAi rice plants had the opposite effect. These results suggest that OsPTR9 might hold potential for improving nitrogen utilization efficiency and grain yield in rice breeding.     

Ultrastructure of the frontal organ in Convoluta and Macrostomum spp.: significance for models of the turbellarian archetype

Present models of turbellarian evolution depict the organism with a frontal organ — a complex of glands whose necks emerge at the anterior tip of the body — and therefore imply that this organ is homologous throughout the Turbellaria. However, comparisons of representatives of the Acoela and Macrostomida, two putatively primitive orders of the Turbellaria, show that frontal organs in these two are not similar in ultrastructure or histochemistry. The acoel Convoluta pulchra had a prominent cluster of frontal mucous glands whose necks emerged together in a frontal pore at the exact apical pole of the organism, and an array of smaller glands of at least five other types opened at the anterior end, separately from and ventral to this pore. The frontal organs (Stirndrüsen) of two species of Macrostomum on the other hand, comprised an array of discretely emerging necks of at least two gland types including one with rhabdiform (rhammite) and one with globular mucous secretion granules neither of which emerge at the apical pole. In neither species did the organ appear to be sensory. Our findings indicate a low probability of homology between the frontal glands of the Acoela and Macrostomida.     

Presynaptic Adenosine A2 and N-Methyl-D-Aspartate Receptors Regulate Dopamine Synthesis in Rat Striatal Synaptosomes

Dopamine synthesis rate and cyclic AMP concentration were measured in synaptosomes prepared from rat striatum. Dopamine synthesis rate was decreased by the addition of either adenosine deaminase or 8-phenyltheophylline, an adenosine receptor blocker, and was increased by the addition of 2-chloroadenosine. The addition of L-glutamate in the absence of adenosine deaminase decreased both dopamine synthesis rate and cyclic AMP concentration; in the presence of adenosine deaminase, glutamate had no effect on basal dopamine synthesis, but enhanced K(+)-stimulated synthesis. Both these effects of glutamate were abolished in Ca2(+)-free medium or in the presence of 2-amino-5-phosphonovalerate, an N-methyl-D-aspartate (NMDA) receptor blocker. In Mg2(+)-free medium with adenosine deaminase, glutamate enhanced both basal and K(+)-stimulated synthesis. These results suggest that dopaminergic terminals have A2 adenosine receptors, whose activation can stimulate dopamine synthesis by a cyclic AMP-dependent mechanism, and NMDA receptors, which modulate dopamine synthesis by a Ca2(+)-dependent mechanism.