Karyological studies of Iranian <Emphasis Type="Italic">Allium</Emphasis> L. (Amaryllidaceae) species with focus on sect. <Emphasis Type="Italic">Acanthoprason</Emphasis>. 1. Mitotic chromosomes

Eighteen species and subspecies (34 accessions) of Allium sect. Acanthoprason and 11 species (17 accessions) belonging to other subgenera and sections of Allium were karyologically investigated and include first reports for 12 species. The examined plants of 47 accessions were diploid, three accessions of two species were tetraploid, and in the A. bisotunense accession, we found a mix of di- and triploid individuals. B chromosomes were found in 10 accessions. A basic chromosome number of x = 8 was confirmed for all investigated members of subg. Melanocrommyum and subg. Allium, and x = 9 for Allium tripedale of subg. Nectaroscordum. Idiograms were drawn for each accession, and metaphase images are presented illustrating observed chromosomal variations. Also, karyotype features and asymmetry parameters were calculated for all accessions. Chromosomal aberrations, e.g. aneuploid cells or loss of whole or parts of chromosome arms, were rarely observed. In general, the karyotypes showed low variation in inter- and intrachromosomal asymmetry especially inside of the taxonomic groups, though satellited chromosomes were good markers for subgenera and even specific for two studied sections of subg. Allium. Six different types of satellites were recognized, two of them were newly described: Type P was prevalent in subg. Melanocrommyum, and type O in sect. Codonoprasum. Statistical analyses were performed on five karyological parameters to test correct relationships and also to test previous grouping hypotheses. Although our data confirm distinct karyological characters for the subgenera investigated, the remarkable morphological diversity inside of subg. Melanocrommyum is not mirrored by striking karyological differences.     

Contrasting patterns and drivers in taxonomic versus functional diversity,and community assembly of aquatic plants in subtropical lakes

Little is known about the differences in patterns and drivers between species richness (SR) and functional diversity (FD) in aquatic plants at large scales, and the underlying assembly mechanisms are not well studied. We compared SR and FD patterns of aquatic plant assemblages in 29 subtropical lakes, and detected the underlying assembly rules. Environmental drivers of SR and FD were revealed by GLM and GAM models, and the relative importance of assembly rules was determined by a null model approach. SR and FD of aquatic plants presented different patterns and drivers in this region. SR was significantly correlated with geographic, hydrological and water quality variables. We found a lower functional richness but higher functional evenness and divergence in the highland lakes. There was no significant correlation between functional richness and environmental variables. Null model analyses showed that most values of standardized effect size were located between the confidence interval, indicating a dominance of randomness. Deterministic processes such as limiting similarity and habitat filtering were also important in individual lakes. Habitat filtering plays a stronger role shaping the hydrophyte assemblages especially with the increase of elevation, area and AWLF (amplitude of water level fluctuation). Our results demonstrated that FD, in contrast to SR, were more resistant to environmental variations, and hydrology played an important role in shaping both SR and FD patterns in lake ecosystems. Furthermore, we revealed complex assembly rules and emphasized the importance of both stochastic and deterministic mechanisms in structuring aquatic plant assemblages at the regional scale.     

Nitrogen fixation ability explains leaf chemistry and arbuscular mycorrhizal responses to fertilization

Atmospheric nitrogen (N) and phosphorus (P) deposition rates are predicted to drastically increase in the coming decades. The ecosystem level consequences of these increases will depend on how plant tissue nutrient concentrations, stoichiometry and investment in nutrient uptake mechanisms such as arbuscular mycorrhizal fungi (AMF) change in response to increased nutrient availability, and how responses differ between plant functional types. Using a factorial nutrient addition experiment with seedlings of multiple N-fixing and non-N-fixing tree species, we examined whether leaf chemistry and AMF responses differ between these dominant woody plant functional groups of tropical savanna and dry forest ecosystems. We found that N-fixers have remarkably stable foliar chemistry that stays constant with external input of nutrients. Non-N-fixers responded to N and N + P addition by increasing both concentrations and total amounts of foliar N, but showed a corresponding decrease in P concentrations while total amounts of foliar P stayed constant, suggesting a ‘dilution’ of tissue P with increased N availability. Non-N-fixers also showed an increase in N:P ratios with N and N + P addition, probably driven by both an increase in N and a decrease in P concentrations. AMF colonization decreased with N + P addition in non-N-fixers and increased with N and N + P addition in N-fixers, suggesting differences in their nutrient acquisition roles in the two plant functional groups. Our results suggest that N-fixers and non-N-fixers can differ significantly in their responses to N and P deposition, with potential consequences for future nutrient and carbon cycling in savanna and dry forest ecosystems.     

A Meta-Analysis of the Relationship between FGFR3 and TP53 Mutations in Bladder Cancer

TP53 and FGFR3 mutations are the most common mutations in bladder cancers. FGFR3 mutations are most frequent in low-grade low-stage tumours, whereas TP53 mutations are most frequent in high-grade high-stage tumours. Several studies have reported FGFR3 and TP53 mutations to be mutually exclusive events, whereas others have reported them to be independent. We carried out a meta-analysis of published findings for FGFR3 and TP53 mutations in bladder cancer (535 tumours, 6 publications) and additional unpublished data for 382 tumours. TP53 and FGFR3 mutations were not independent events for all tumours considered together (OR = 0.25 [0.18–0.37], p = 0.0001) or for pT1 tumours alone (OR = 0.47 [0.28–0.79], p = 0.0009). However, if the analysis was restricted to pTa tumours or to muscle-invasive tumours alone, FGFR3 and TP53 mutations were independent events (OR = 0.56 [0.23–1.36] (p = 0.12) and OR = 0.99 [0.37–2.7] (p = 0.35), respectively). After stratification of the tumours by stage and grade, no dependence was detected in the five tumour groups considered (pTaG1 and pTaG2 together, pTaG3, pT1G2, pT1G3, pT2-4). These differences in findings can be attributed to the putative existence of two different pathways of tumour progression in bladder cancer: the CIS pathway, in which FGFR3 mutations are rare, and the Ta pathway, in which FGFR3 mutations are frequent. TP53 mutations occur at the earliest stage of the CIS pathway, whereas they occur would much later in the Ta pathway, at the T1G3 or muscle-invasive stage.     

An uncommon H3/Ser10 phosphorylation pattern in Cestrum strigilatum (Solanaceae), a species with B chromosomes

Cestrum strigilatum (Solanaceae) is a South American shrub with B chromosomes. Bs show a univalent behavior when a single B is present, have non-Mendelian segregation, and are poor in genes and rich in repetitive DNA. In this study, the histone H3 at serine 10 (H3/Ser10) phosphorylation pattern was investigated during mitosis and meiosis of C. strigilatum collected from the wild and was compared in A and B chromosomes. The results revealed that H3/Ser10 phosphorylation of A chromosomes occurred only in the pericentromeric region in both mitosis and meiosis, whereas in the B univalent, phosphorylation appeared in almost the whole extent of the chromosome, except in the terminal portion of the long arm. In meiosis II, the phosphorylation of A chromosomes was similar to that in the first division of meiosis, but the Bs did not show H3/Ser10 phosphorylation. Our results suggest that phosphorylation at the pericentromeric region may be associated with chromosome motility during cell divisions and with the cohesion of B chromatids in a univalent structure in meiosis I.     

Detection of singlet oxygen and superoxide with fluorescent sensors in leaves under stress by photoinhibition or UV radiation

In order to understand the physiological functions of reactive oxygen species (ROS) generated in leaves, their direct measurement in vivo is of special importance. Here we report experiments with two dansyl-based ROS sensors, the singlet oxygen specific DanePy and HO-1889NH, which is reactive to both singlet oxygen and superoxide radicals. Here we report in vivo detection of (1)O(2) and O(2)(-*) by fluorescence quenching of two dansyl-based ROS sensors, the (1)O(2) specific DanePy and HO-1889NH, which was reactive with both (1)O(2) and O(2)(-*). The ROS sensors were administered to spinach leaves through a pinhole, and then the leaves were exposed to either excess photosynthetically active radiation or UV (280-360 nm) radiation. Microlocalization of the sensors' fluorescence and its ROS-induced quenching was followed with confocal laser scanning microscopy and with fluorescence imaging. These sensors were specifically localized in chloroplasts. Quenching analysis indicated that the leaves exposed to strong light produced (1)O(2), but hardly any O(2)(-*). On the other hand, the dominant ROS in UV-irradiated leaves was O(2)(-*), while (1)O(2) was minor.     

Intranuclear inclusions in fine needle aspirates of bronchial low grade mucoepidermoid carcinoma with clear cell change: a report of two cases

BACKGROUND: Mucoepidermoid carcinoma of the bronchus is a rare neoplasm that can be recognized on histology as well as cytology by the presence of three characteristic cell types: mucus secreting, epidermoid and intermediate. We encountered two cases displaying unusual cytologic features, including clear intranuclear inclusions. CASES: Two females, aged 33 and 39, presented with an intrabronchial tumor and pulmonary parenchymatous mass, respectively. Fine needle aspiration of both tumors showed similar cytologic features, with a dominant population of cells with bland nuclei and wide cytoplasm, and frequent intranuclear inclusions. A minor component of mucus-secreting cells was also recognized. Histologically, both tumors corresponded to the clear cell variant of mucoepidermoid carcinoma. CONCLUSION: The cytologic picture in our cases has not been described previously in fine needle aspirates of mucoepidermoid carcinoma, in neither the bronchus nor salivary gland. The differential diagnosis of a monotonous population of epithelial cells with intranuclear inclusions involves bronchioloalveolar carcinoma, but the absence of the characteristic sheet pattern, as well as the clinical and image findings, excludes this possibility. The lack of atypia and intrabronchial location limits the scope to carcinoid and salivary gland-type tumors of the bronchus. Since we were aware of the possibility of unusual cytologic presentations of mucoepidermoid carcinomas, search for different cellular populations suggested the precise diagnosis.     

Clathrin-associated proteins contain bound nucleotide

An alcohol dehydrogenase isolated from Zymomonas mobilis was found to be activated by ferrous ions but not by zinc, after inactivation with metal-complexing agents. Cobaltous ions also re-activated to a lesser extent. It is suggested that in this species the alcohol dehydrogenase naturally contains iron. Kinetic studies on the iron-treated enzyme indicate an 'alcohol activation' phenomenon, which may have physiological relevance in overcoming product inhibition during fermentation.     

Crystal and molecular structure of (E)-5-(2-bromovinyl-2''-deoxyuridine)

(E)-5-(2-bromovinyl-2'-deoxyuridine) crystallizes in the space group P2(1) with a = 12.976(1), b = 4.800(1), c = 20.385(2) A, beta = 96.88(1) degrees, Z = (two molecules a and b in the asymmetric unit). The structure has been determined by the use of 2400 diffractometer reflexions and refined by least-squares to R of 0.053. Conformational features of both molecules a and b resemble those of thymidine. The ribofuranose rings assume the rare C(3')-exo form observed also in thymidine. Similarly, the torsion angles around the glycosidic bonds (mean = 40(1) and 56(1) degrees fall in the anti range. In each molecule the best plane of the 2-bromovinyl moiety is bent out of the least-squares plane of the pyrimidine base by 6 degrees, so that the positively charged C(8)-H(8) group can donate an intramolecular hydrogen bond to 0(4) atom. Eight strong and weak intermolecular hydrogen bridges are built up between the symmetry independent and related molecules forming a complicated three dimensional hydrogen bond network.     

Ribosomal proteins as biomarkers for bacterial identification by mass spectrometry in the clinical microbiology laboratory

Whole-cell matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) is a rapid method for identification of microorganisms that is increasingly used in microbiology laboratories. This identification is based on the comparison of the tested isolate mass spectrum with reference databases. Using Neisseria meningitidis as a model organism, we showed that in one of the available databases, the Andromas database, 10 of the 13 species-specific biomarkers correspond to ribosomal proteins. Remarkably, one biomarker, ribosomal protein L32, was subject to inter-strain variability. The analysis of the ribosomal protein patterns of 100 isolates for which whole genome sequences were available, confirmed the presence of inter-strain variability in the molecular weight of 29 ribosomal proteins, thus establishing a correlation between the sequence type (ST) and/or clonal complex (CC) of each strain and its ribosomal protein pattern. Since the molecular weight of three of the variable ribosomal proteins (L30, L31 and L32) was included in the spectral window observed by MALDI-TOF MS in clinical microbiology, i.e., 3640–12000 m/z, we were able by analyzing the molecular weight of these three ribosomal proteins to classify each strain in one of six subgroups, each of these subgroups corresponding to specific STs and/or CCs. Their detection by MALDI-TOF allows therefore a quick typing of N. meningitidis isolates.