Interpretation of the invertebrate-based BMWP-PL index in a gravel-bed river: insight from the Polish Carpathians

Like its British prototype (Biological Monitoring Working Party score system), the Polish benthic invertebrate-based BMWP-PL index is commonly regarded as an indicator of river water quality. This interpretation of the index has been verified in a study of the gravel-bed Bia?a River. Benthic macroinvertebrates were sampled at 10 sites and compared in one channelized and one unmanaged cross-section per site. The resulting taxa richness and BMWP-PL index scores were compared with water quality and physical habitat characteristics in the cross-sections. Channelized and unmanaged cross-sections clearly differed in their physical habitat conditions, and water quality characteristics mostly varied in the downstream direction. Particular cross-sections hosted between 3 and 26 invertebrate taxa, with the respective BMWP-PL scores indicating the water in the surveyed cross-sections varied between high and poor quality. However, the BMWP-PL scores were unrelated to physicochemical characteristics of the river water, which consistently pointed to high water quality. Instead, the scores were significantly related to several physical habitat variables, with the number of low-flow channels in a cross-section explaining the largest proportion of the variance in the index values. The relationship of the scores with the complexity of flow pattern in the river and a lack of their dependence on physicochemical water characteristics show that the BMWP-PL index should not be regarded as an indicator of water quality but rather as an indicator of the ecological status of rivers, dependent both on their hydromorphological and water-quality characteristics.     

Chemerin Is an Antimicrobial Agent in Human Epidermis

Chemerin, a chemoattractant ligand for chemokine-like receptor 1 (CMKLR1) is predicted to share similar tertiary structure with antibacterial cathelicidins. Recombinant chemerin has antimicrobial activity. Here we show that endogenous chemerin is abundant in human epidermis, and that inhibition of bacteria growth by exudates from organ cultures of primary human skin keratinocytes is largely chemerin-dependent. Using a panel of overlapping chemerin-derived synthetic peptides, we demonstrate that the antibacterial activity of chemerin is primarily mediated by Val⁶⁶-Pro⁸⁵, which causes direct bacterial lysis. Therefore, chemerin is an antimicrobial agent in human skin.     

By Regulating Mitochondrial Ca2+-Uptake UCP2 Modulates Intracellular Ca2+

Introduction

The possible role of UCP2 in modulating mitochondrial Ca²⁺-uptake (mCa²⁺-uptake) via the mitochondrial calcium uniporter (MCU) is highly controversial.

Methods

Thus, we analyzed mCa²⁺-uptake in isolated cardiac mitochondria, MCU single-channel activity in cardiac mitoplasts, dual Ca²⁺-transients from mitochondrial ((Ca²⁺)m) and intracellular compartment ((Ca²⁺)c) in the whole-cell configuration in cardiomyocytes of wild-type (WT) and UCP2^-/- mice.

Results

Isolated mitochondria showed a Ru360 sensitive mCa²⁺-uptake, which was significantly decreased in UCP2^-/- (229.4±30.8 FU vs. 146.3±23.4 FU, P<0.05). Single-channel registrations confirmed a Ru360 sensitive voltage-gated Ca²⁺-channel in mitoplasts, i.e. mCa1, showing a reduced single-channel activity in UCP2^-/- (Po,total: 0.34±0.05% vs. 0.07±0.01%, P<0.05). In UCP2^-/- cardiomyocytes (Ca²⁺)m was decreased (0.050±0.009 FU vs. 0.021±0.005 FU, P<0.05) while (Ca²⁺)c was unchanged (0.032±0.002 FU vs. 0.028±0.004 FU, P>0.05) and transsarcolemmal Ca²⁺-influx was inhibited suggesting a possible compensatory mechanism. Additionally, we observed an inhibitory effect of ATP on mCa²⁺-uptake in WT mitoplasts and (Ca²⁺)m of cardiomyocytes leading to an increase of (Ca²⁺)c while no ATP dependent effect was observed in UCP2^-/-.

Conclusion

Our results indicate regulatory effects of UCP2 on mCa²⁺-uptake. Furthermore, we propose, that previously described inhibitory effects on MCU by ATP may be mediated via UCP2 resulting in changes of excitation contraction coupling.     

Raman imaging of changes in the polysaccharides distribution in the cell wall during apple fruit development and senescence

Planta - Du ring on-tree ripening, the pectin distribution changed from polydispersed in cell wall to cumulated in cell wall corners. During apple storage, the pectin distribution returned to...     

Assessment of the influence of viscoelasticity of cornea in animal ex vivo model using air‐puff optical coherence tomography and corneal hysteresis

Application of the air‐puff swept source optical coherence tomography (SS‐OCT) instrument to determine the influence of viscoelasticity on the relation between overall the air‐puff force and corneal apex displacement of porcine corneas ex vivo is demonstrated. Simultaneous recording of time‐evolution of the tissue displacement and air pulse stimulus allows obtaining valuable information related in part to the mechanical properties of the cornea. A novel approach based on quantitative analysis of the corneal hysteresis of OCT data is presented. The corneal response to the air pulse is assessed for different well‐controlled intraocular pressure (IOP) levels and for the progression of cross‐linking‐induced stiffness of the cornea. Micrometer resolution, fast acquisition and noncontact character of the air‐puff SS‐OCT measurements have potential to improve the in vivo assessment of mechanical properties of the human corneas.      

Physicochemical and biological analysis of synthetic bacterial lipopeptides: validity of the concept of endotoxic conformation

The importance of the biological function and activity of lipoproteins from the outer or cytoplasmic membranes of Gram-positive and Gram-negative bacteria is being increasingly recognized. It is well established that they are like the endotoxins (lipopolysaccharide (LPS)), which are the main amphiphilic components of the outer membrane of Gram-negative bacteria, potent stimulants of the human innate immune system, and elicit a variety of proinflammatory immune responses. Investigations of synthetic lipopeptides corresponding to N-terminal partial structures of bacterial lipoproteins defined the chemical prerequisites for their biological activity and in particular the number and length of acyl chains and sequence of the peptide part. Here we present experimental data on the biophysical mechanisms underlying lipopeptide bioactivity. Investigation of selected synthetic diacylated and triacylated lipopeptides revealed that the geometry of these molecules (i.e. the molecular conformations and supramolecular aggregate structures) and the preference for membrane intercalation provide an explanation for the biological activities of the different lipopeptides. This refers in particular to the agonistic or antagonistic activity (i.e. their ability to induce cytokines in mononuclear cells or to block this activity, respectively). Biological activity of lipopeptides was hardly affected by the LPS-neutralizing antibiotic polymyxin B, and the biophysical interaction characteristics were found to be in sharp contrast to that of LPS with polymyxin B. The analytical data show that our concept of "endotoxic conformation," originally developed for LPS, can be applied also to the investigated lipopeptide and suggest that the molecular mechanisms of cell activation by amphiphilic molecules are governed by a general principle.     

Stability and instability processes in the calli of Fagopyrum tataricum that have different morphogenic potentials

Plant Cell, Tissue and Organ Culture (PCTOC) - The morphogenic callus (MC) of Fagopyrum tataricum contains a large amount of flavonoids, especially rutin, and exhibits a high level of antioxidant...     

Diversity of bacteriocins in the microbiome of the Tucuruí Hydroelectric Power Plant water reservoir and three-dimensional structure prediction of a zoocin

Bacteriocins are antimicrobial peptides expressed by bacteria through ribosomal activity. In this study, we analyzed the diversity of bacteriocin-like genes in the Tucuruí-HPP using a whole-metagenome shotgun sequencing approach. Three layers of the water column were analyzed (photic, aphotic and sediment). Detection of bacteriocin-like genes was performed with blastx using the BAGEL4 database as subject sequences. In order to calculate the abundance of bacteriocin-like genes we also determined the number of 16S rRNA genes using blastn. Taxonomic analysis was performed using RAST server and the metagenome was assembled using IDBA-UD in order to recover the full sequence of a zoocin which had its three-dimensional structure determined. The photic zone presented the highest number of reads affiliated to bacteriocins. The most abundant bacteriocins were sonorensin, Klebicin D , pyocin and colicin. The zoocin model was composed of eight anti-parallel β-sheets and two α-helices with a Zn²⁺ ion in the active site. This model was considerably stable during 10 ns of molecular dynamics simulation. We observed a high diversity of bacteriocins in the Tucuruí-HPP, demonstrating that the environment is an inexhaustible source for prospecting these molecules. Finally, the zoocin model can be used for further studies of substrate binding and molecular mechanisms involving peptidoglycan degradation.     

A postmitotic role for Isl-class LIM homeodomain proteins in the assignment of visceral spinal motor neuron identity

LIM homeobox genes have a prominent role in the regulation of neuronal subtype identity and distinguish motor neuron subclasses in the embryonic spinal cord. We have investigated the role of Isl-class LIM homeodomain proteins in motor neuron diversification using mouse genetic methods. All spinal motor neuron subtypes initially express both Isl1 and Isl2, but Isl2 is rapidly downregulated by visceral motor neurons. Mouse embryos lacking Isl2 function exhibit defects in the migration and axonal projections of thoracic level motor neurons that appear to reflect a cell-autonomous switch from visceral to somatic motor neuron character. Additional genetic mutations that reduce or eliminate both Isl1 and Isl2 activity result in more pronounced defects in visceral motor neuron generation and erode somatic motor neuron character. Thus, an early phase of high Isl expression and activity in newly generated motor neurons permits the diversification of visceral and somatic motor neuron subtypes in the developing spinal cord.