Structural and mechanistic insights into a Bacteroides vulgatus retaining N-acetyl-β-galactosaminidase that uses neighbouring group participation

Bacteroides vulgatus is a member of the human microbiota whose abundance is increased in patients with Crohn's disease. We show that a B. vulgatus glycoside hydrolase from the carbohydrate active enzyme family GH123, BvGH123, is an N-acetyl-β-galactosaminidase that acts with retention of stereochemistry, and, through a 3-D structure in complex with Gal-thiazoline, provide evidence in support of a neighbouring group participation mechanism

Central Crosstalk for Somatic Tinnitus: Abnormal Vergence Eye Movements

Frequent oulomotricity problems with orthoptic testing were reported in patients with tinnitus. This study examines with objective recordings vergence eye movements in patients with somatic tinnitus patients with ability to modify their subjective tinnitus percept by various movements, such as jaw, neck, eye movements or skin pressure.Vergence eye movements were recorded with the Eyelink II video system in 15 (23–63 years) control adults and 19 (36–62 years) subjects with somatic tinnitus.1) Accuracy of divergence but not of convergence was lower in subjects with somatic tinnitus than in control subjects. 2) Vergence duration was longer and peak velocity was lower in subjects with somatic tinnitus than in control subjects. 3) The number of embedded saccades and the amplitude of saccades coinciding with the peak velocity of vergence were higher for tinnitus subjects. Yet, saccades did not increase peak velocity of vergence for tinnitus subjects, but they did so for controls. 4) In contrast, there was no significant difference of vergence latency between these two groups.The results suggest dysfunction of vergence areas involving cortical-brainstem-cerebellar circuits. We hypothesize that central auditory dysfunction related to tinnitus percept could trigger mild cerebellar-brainstem dysfunction or that tinnitus and vergence dysfunction could both be manifestations of mild cortical-brainstem-cerebellar syndrome reflecting abnormal cross-modality interactions between vergence eye movements and auditory signals

Prophage exotoxins enhance colonization fitness in epidemic scarlet fever-causing Streptococcus pyogenes

Abstract: The re-emergence of scarlet fever poses a new global public health threat. The capacity of North-East Asian serotype M12 (emm12) Streptococcus pyogenes (group A Streptococcus, GAS) to cause scarlet fever has been linked epidemiologically to the presence of novel prophages, including prophage ΦHKU.vir encoding the secreted superantigens SSA and SpeC and the DNase Spd1. Here, we report the molecular characterization of ΦHKU.vir-encoded exotoxins. We demonstrate that streptolysin O (SLO)-induced glutathione efflux from host cellular stores is a previously unappreciated GAS virulence mechanism that promotes SSA release and activity, representing the first description of a thiol-activated bacterial superantigen. Spd1 is required for resistance to neutrophil killing. Investigating single, double and triple isogenic knockout mutants of the ΦHKU.vir-encoded exotoxins, we find that SpeC and Spd1 act synergistically to facilitate nasopharyngeal colonization in a mouse model. These results offer insight into the pathogenesis of scarlet fever-causing GAS mediated by prophage ΦHKU.vir exotoxins

Architektura osobników Ambrosia psilostachya DC. w różnych warunkach siedliskowych

Ambrosia psilostachya is a plant of North American origin, well-domesticated in Poland. It covers ruderal habitats and is found in crops and in city green areas. The density of ragweed shoots in the researched areas ranged from 55 to 111 per m2. The production of biomass of this species relates to the production of synanthropic communities and city lawns. The factor limiting the population is cutting which affects mostly the number of shoots per patch, less considerably the state of a single individual. Habitats affected by mechanical factors are the biggest source of pollen causing allergies.Ambrosia psilostachya jest rośliną pochodzenia północnoamerykańskiego trwale zadomowioną w Polsce. Zajmuje siedliska ruderalne, spotykana jest w uprawach i terenach zieleni miejskiej. Zagęszczenie pędów ambrozji na badanych powierzchniach wahało się od 55 do 111 na m2. Produkcja biomasy tego gatunku nawiązuje do produkcji zbiorowisk synantropijnych i kultywowanych trawników miejskich. Poza obszarem naturalnego występowania ambrozja rośnie w nieco większym zagęszczeniu i jej osobniki osiągają większą biomasę. Koszenie nie jest czynnikiem eliminującym okazy ze zbiorowisk roślinnych. Ogranicza liczbę pędów w płacie, w mniejszym stopniu wpływa na stan pojedynczego osobnika. Największym źródłem wywołującego alergie pyłku ambrozji są siedliska poddawane oddziaływaniom mechanicznym

Habitat and phytocenosis conditions of the occurrence of Ostericum palustre in the Natura 2000 „Lisi Kat” site

Ostericum palustre Besser is a species protected by the domestic and EU laws. In Poland it occurs in about 150 sites one of which is located in the area covered by Natura 2000 “Lisi Kąt”. The population existing there, estimated as 35,000 individuals, covers the acreage of 342 ha. The species persists there mostly in over-dried and transformed-by-meadow-management reed beds with the share of Carex acutiformis and C. gracilis, in phytocenoses of Scheuchzerio-Caricetea nigrae with a large share of mosses, in overgrowing patches of the alliances of Molinion as well as sporadically within reed beds with Carex pseudocyperus. Its share in similar phytocenoses coincides with the reports in literature in the region of the Noteć Valley. In most cases those are heavily disturbed systems, transitional in nature, which must have been the reason for a relatively high level of species variation. The habitat preferences of Ostericum palustre, determined with Ellenberg's indicator values (L, T), correspond to the values optimal for the species. Soil, on the other hand, can be referred to as slightly acid, average fertile and mostly moist

Genetic polymorphism in "mixed" colonies of wood ants (Hymenoptera: Formicidae) in southern Finland and its possible origin

Wood ant colonies that appear to consist of individuals representing different species are described in several previous papers. The present study is the first to elucidate the genetic basis of the spectacular morphological variability observed within such colonies. Two seemingly mixed colonies (FM-1 and FM-2) from southern Finland were investigated. On the basis of the morphology of their workers these colonies were comprised of individuals with phenotypes typical of Formica rufa L., F. polyctena Först., and F. aquilonia Yarr. The sequence of an mtDNA fragment (5' end of the cytochrome b gene) was used to examine the phylogenetic relationships among haplotypes of workers from homogeneous colonies of different wood ant species and the two supposedly mixed colonies, and to sort the individuals within the colonies into matrilines. Six microsatellite loci were used to analyse the genetic differentiation between colonies and among workers within colonies, and to detect putative hybrids. The results show that, independently of their phenotype, workers from the "mixed" colonies were genetically more similar to other individuals in their colony than to those in the homogeneous F. rufa, F. polyctena or F. aquilonia colonies. However, while colony FM-1 consisted of offspring of the same queen or more likely several maternally related queens, colony FM-2 consisted of the offspring of at least four unrelated queens. The data suggest hybridisation between F. polyctena × F. aquilonia and F. polyctena × F. rufa (and possibly subsequent mating between these hybrids) as the most probable mechanism leading to the existence of these two colonies, which implies that the hybrids are fertile. This study shows that colonies of wood ant hybrids can arise spontaneously and persist under natural conditions. The results also revealed that even some morphologically homogeneous colonies are genetically heterogeneous. In the case of closely related, morphologically similar species that interbreed, morphology can be a bad predictor of genetic differences between individuals

Walory przyrodnicze i paszowe zbiorowiska z Carex nigra w dolinie kanału Bydgoskiego

Carex nigra Reichard is a relatively constant species typical of damp and inundated habitats. One of the species that gain the highest cover in meadow communities with common sedge is Ostericum palustre Besser. This work presented comparison of communities with predomination of C.nigra or O. palustre in phytocenotic and yield- forming aspects. In floristic terms, Pratocenoses with C. nigra or O. palustre refer to meadows from the alliance Molinion . Their sward contains small proportion of valuable meadow plants. Habitat differences of both variants determined based on the Ellenberg indices indicate more alkaline character of the subsoil of patches with O. palustre . Yields obtained from the studied areas dominated by C. nigra were on average by about 1 Mg · ha -1 lower and by C. nigra and O. palustre by about 1.5 Mg · ha -1 lower than the mean national meadow productivity. Phosphorus and potassium content was lower than that required in feeding standards. Phosphorus and potassium occurred in larger amounts in sward with O. palustre. Proportion of O. palustre improved calcium balance particularly in the second regrowth. In general agricultural evaluation studied communities should be regarded as low-value. Consequently the main reason for their maintenance is their natural values connected with protection of plant communities and natural habitats.Stosunkowo trwałym gatunkiem właściwym dla siedlisk wilgotnych i podtapianych jest C. nigra. Jednym z gatunków osiągających najwyższe pokrycie w zbiorowiskach łąkowych z turzycą pospolitą jest O. palustre. W pracy przedstawiono porównanie pod względem fitocenotycznym i plonotwórczym zbiorowisk z dominacją C. nigra lub O. palustre. Pratocenozy z C. nigra lub O. palustre pod względem florystycznym nawiązują do łąk ze związku Molinion. W ich runi niewielki jest udział wartościowych roślin łąkowych. Różnice siedliskowe obu wariantów określone na podstawie wskaźników Ellenberga wskazują na bardziej alkaliczny charakter podłoża płatów z O. palustre. Plony uzyskiwane z badanych powierzchni zdomi-nowanych przez C. nigra były średnio o około 1 Mg·ha-1, a C. nigra i O. palustre o około 1,5 Mg·ha-1 mniejsze od średniej krajowej wydajności łąk. Zawartość fosforu i potasu była niższa od wymaganej w normach żywieniowych. Fosfor i potas w większych ilościach występowały w runi z O. palustre. Udział O. palustre poprawiał bilans wapnia zwłaszcza w drugim odroście. W ogólnej ocenie rolniczej badane zbiorowiska należy uznać za mało wartościowe. Tym samym głównym motywem ich utrzymywania są wartości przyrodnicze związane z ochroną zbiorowisk roślinnych i siedlisk przyrodniczych

Functional Annotation and Three-Dimensional Structure of an Incorrectly Annotated Dihydroorotase from cog3964 in the Amidohydrolase Superfamily

The substrate specificities of two incorrectly annotated enzymes belonging to cog3964 from the amidohydrolase superfamily were determined. This group of enzymes are currently misannotated as either dihydroorotases or adenine deaminases. Atu3266 from Agrobacterium tumefaciens C58 and Oant2987 from Ochrobactrum anthropi ATCC 49188 were found to catalyze the hydrolysis of acetyl-(R)-mandelate and similar esters with values of k(cat)/K(m) that exceed 10(5) M(-1) s(-1). These enzymes do not catalyze the deamination of adenine or the hydrolysis of dihydroorotate. Atu3266 was crystallized and the structure determined to a resolution of 2.62 Å. The protein folds as a distorted (β/α)(8) barrel and binds two zincs in the active site. The substrate profile was determined via a combination of computational docking to the three-dimensional structure of Atu3266 and screening of a highly focused library of potential substrates. The initial weak hit was the hydrolysis of N-acetyl-D-serine (k(cat)/K(m) = 4 M(-1) s(-1)). This was followed by the progressive identification of acetyl-(R)-glycerate (k(cat)/K(m) = 4 × 10(2) M(-1) s(-1)), acetyl glycolate (k(cat)/K(m) = 1.3 × 10(4) M(-1) s(-1)), and ultimately acetyl-(R)-mandelate (k(cat)/K(m) = 2.8 × 10(5) M(-1) s(-1))