Regulators of cell volume: The structural and functional properties of anion channels of the LRRC8 family

Members of the LRRC8 family participate in the response of vertebrate cells to osmotic changes in their environment. These proteins form heteromeric assemblies composed of the obligatory subunit LRRC8A and at least one of the other four homologs, which together function as anion-selective channels with distinct properties that are activated upon cell-swelling. The hexameric complexes share a conserved architecture consisting of a membrane-inserted pore domain with an ion permeation path located at the axis of symmetry and cytoplasmic leucine-rich repeat domains that regulate the open probability of the channel. In this review, we summarize the current understanding of structure-function relationships of these unusual ion channels whose mechanisms are, despite their large physiological importance, still poorly understood

Input of heavy metals to the forest floor as the result of zinc smelter pollution in southern Poland

The aim of this study was to assess the impact of zinc smelter on heavy metals concentration in the litter fall collected from three different sites in Olkusz Forest located in southern Poland. Furthermore the study was designed to investigate the input of these metals to the forest floor. Three forest areas Podlesie I and Podlesie II located 3 and 4 km south-east from Bukowno zinc smelter and Cegielnia situated 6 km north-east from the smelter were selected. At the beginning of September 2006 five litter traps were set at each site. The quantity of litter fall, along with percent age composition of each species, were estimated for an area of 1m^2. The concentration of Cd, Pb, Cu, Zn and Fe in the litter fall and leaves of four main tree species were analysed. The input of these metals to the forest floor were determined. The input of cadmium ranged from 204 μg m^2 at Cegielnia to 1340 μg m^2 at Podlesie I. The input of lead was higher than cadmium and varied from 1031 μg m^2 at Cegielnia to 3252 μg m^2 at Podlesie II. The input of zinc and iron were about 10 times than cadmium and lead. The less input of all invesigated metals was noticed in control site located at WNP. for those metals. The high input of heavy metals to the forest floor may have negative effects on investigated part of Olkusz forest ecosystem

Structure of a volume-regulated heteromeric LRRC8A/C channel

Volume-regulated anion channels (VRACs) participate in the cellular response to osmotic swelling. These membrane proteins consist of heteromeric assemblies of LRRC8 subunits, whose compositions determine permeation properties. Although structures of the obligatory LRRC8A, also referred to as SWELL1, have previously defined the architecture of VRACs, the organization of heteromeric channels has remained elusive. Here we have addressed this question by the structural characterization of murine LRRC8A/C channels. Like LRRC8A, these proteins assemble as hexamers. Despite 12 possible arrangements, we find a predominant organization with an A:C ratio of two. In this assembly, four LRRC8A subunits cluster in their preferred conformation observed in homomers, as pairs of closely interacting proteins that stabilize a closed state of the channel. In contrast, the two interacting LRRC8C subunits show a larger flexibility, underlining their role in the destabilization of the tightly packed A subunits, thereby enhancing the activation properties of the protein

R-loop formation and conformational activation mechanisms of Cas9

Cas9 is a CRISPR-associated endonuclease capable of RNA-guided, site-specific DNA cleavage$^{1-3}$. The programmable activity of Cas9 has been widely utilized for genome editing applications$^{4-6}$, yet its precise mechanisms of target DNA binding and off-target discrimination remain incompletely understood. Here we report a series of cryo-electron microscopy structures of Streptococcus pyogenes Cas9 capturing the directional process of target DNA hybridization. In the early phase of R-loop formation, the Cas9 REC2 and REC3 domains form a positively charged cleft that accommodates the distal end of the target DNA duplex. Guide-target hybridization past the seed region induces rearrangements of the REC2 and REC3 domains and relocation of the HNH nuclease domain to assume a catalytically incompetent checkpoint conformation. Completion of the guide-target heteroduplex triggers conformational activation of the HNH nuclease domain, enabled by distortion of the guide-target heteroduplex, and complementary REC2 and REC3 domain rearrangements. Together, these results establish a structural framework for target DNA-dependent activation of Cas9 that sheds light on its conformational checkpoint mechanism and may facilitate the development of novel Cas9 variants and guide RNA designs with enhanced specificity and activity

Wartość odżywcza i prozdrowotna wybranych warzyw z rodzaju kapusta (Brassica L.)

The paper characterises selected vegetable species of the Brassica genus: white headed cabbage (Brassica oleracea L. var. capitata f. alba), savoy cabbage (Brassica oleracea L. var. sabauda L.), napa cabbage ((Brassica rapa L. subsp. pekinensis), broccoli (Brassica oleracea L. var. italica), kale (Brassica oleracea L. var. sabellica L.), cauliflower (Brassica oleracea L. var. botrytis), kohlrabi (Brassica oleracea L. var. gongylodes L.), Brussels sprout (Brassica oleracea L. var. gemmifera). It describes their medicinal properties and economic importance, as well as presents their value as a resource for the food and pharmaceutical industries. Brassicas arecharacterised by high vitamin and mineral content and have various medicinal properties. They also have a high nutritional value, high antioxidative activity and health benefits. From the point of view of nutrition, brassicas are perceived as valuable in cancer prevention. It is noteworthy that kale (Brassica oleracea L. var. gongylodes L.) is characterised by significant nutritional and health benefits, yet it is not popular in Poland.Scharakteryzowano wybrane gatunki warzyw należące do rodzaju Brassica: kapusta głowiasta biała (Brassica oleracea L. var. capitata f. alba), kapusta włoska (Brassica oleracea L. var. sabauda L.), kapusta pekińska (Brassica rapa L. subsp. pekinensis), brokuł(Brassica oleracea L. var. italica), jarmuż (Brassica oleracea L. var. sabellica L.), kalafior (Brassica oleracea L. var. botrytis L.), kalarepa (Brassica oleracea var. gongylodes L.), kapusta brukselska (Brassica oleracea L. var. gemmifera). Opisano prozdrowotne właściwościlecznicze, znaczenie gospodarcze, a także przedstawiono znaczenie ich jako surowca dla przemysłu spożywczego i farmaceutycznego. Warzywa kapustne charakteryzują się wysoką zawartością witamin i minerałów, zawierają wiele cennych właściwości leczniczych. Posiadają wysoką wartość odżywczą, dużą aktywność przeciwutleniajacą, a także wykazują działanie prozdrowotne. Z żywieniowego punktu widzenia warzywa należące do rodziny kapustowatych są postrzegane jako produkty o dużym znaczeniu w profilaktyce nowotworowej. Na szczególną uwagę zasługuje jarmuż (Brassica oleracea L. var. acephala), który charakteryzuje się wysokimi walorami odżywczymi i prozdrowotnymi, a jednocześnie jest warzywem mało popularnym w Polsce