Osservazioni Anatomiche Su Una Forma Teratologica Di Tulipa Orientalis Levier

Abstract

Anatomical observations upon a teratological form of TULIPA ORIENTALIS Levier. — The author illustrates a singular case of abnormal concomimitances in Tulipa orientalis Levier, which hears six flowers on the same scape: three of these flowers are disposed in a terminal « bouquet » and three at different heights in the scape.

Almost all the pistils of these flowers were tetracarpellate; one of them being greatly hypertrophic in respect of the others, and completely devoided of ovules.

Very interesting for its rarity and here observed for the first time for the Tulipa genus, is the presence of a very small and almost perfect supernumerary tetracarpellate pistil, joining the normal pistil of one of the terminal flowers, and the origine of which can't be ascribed to a simple scission, but only to an evident case of multiplication as the two pistils appear distinctely independent.     

Osservazioni carioembriologiche in Ornithogalum di Sardegna: Nota I. - Sporogenesi e sviluppo dei gametofiti in Ornithogalum caudatum Ait

Abstract

CARYOEMBRYOLOGICAL STUDIES in ORNITHOGALUM OF SARDINIA.

I. - SPOROGENESIS AND DEVELOPMENT OF THE GAMETOPHYTES IN ÒRNITHOGALUM CAUDATUM AIT. — After a concise synthesis of the caryoembryological knowledges regarding the taxa of Ornithogalum present in Sardinia, the embryology and morphology of Ornithogalum caudatum Ait., have been investigated.

In a three-locular ovary the ovules are anatropous, epitropous with nucellus crassinucellate and only one archesporial cell evolves a mother cell.

The development of the female gametophyte tallies with the Polygonum (Normal) Type.

The homoetypical division presents an asynchronous proceeding in the cellules of the dyad with a considerable delay in the two-nucleate arrangement, especially in the chalazal cell.

Antipodal cells present a hypertrophic growing, but they present no tendency to polyantipody.

The endosperm is of the Helobiae Type.

The divisions of the pollen mother-cells are of the successive Type.

Longest axis of 1-sulcate pollen grains about 76 micron.

A true tapetal periplasmodium isn't formed in the anthers.

The chromosome number is 2n = 54.

Raphides accour in the cataphylls, in the parenchymatous tissues of the leaf and in several parts of the floral region.     

Expression of Immunoglobulin Receptors with Distinctive Features Indicating Antigen Selection by Marginal Zone B Cells from Human Spleen

Marginal zone (MZ) B cells, identified as surface (s)IgM^highsIgD^lowCD23^low/−CD21⁺CD38⁻ B cells, were purified from human spleens, and the features of their V(D)J gene rearrangements were investigated and compared with those of germinal center (GC), follicular mantle (FM) and switched memory (SM) B cells. Most MZ B cells were CD27⁺ and exhibited somatic hypermutations (SHM), although to a lower extent than SM B cells. Moreover, among MZ B-cell rearrangements, recurrent sequences were observed, some of which displayed intraclonal diversification. The same diversifying sequences were detected in very low numbers in GC and FM B cells and only when a highly sensitive, gene-specific polymerase chain reaction was used. This result indicates that MZ B cells could expand and diversify in situ and also suggested the presence of a number of activation-induced cytidine deaminase (AID)-expressing B cells in the MZ. The notion of antigen-driven expansion/selection in situ is further supported by the VH CDR3 features of MZ B cells with highly conserved amino acids at specific positions and by the finding of shared (“stereotyped”) sequences in two different spleens. Collectively, the data are consistent with the notion that MZ B cells are a special subset selected by in situ antigenic stimuli.     

Biological and clinical relevance of quantitative global methylation of repetitive DNA sequences in chronic lymphocytic leukemia

Global DNA hypomethylation affecting repeat sequences has been reported in different cancer types. Herein, we investigated the methylation levels of repetitive DNA elements in chronic lymphocytic leukemia (CLL), their correlation with the major cytogenetic and molecular features, and clinical relevance in predicting therapy-free survival (TFS). A quantitative bisulfite-PCR Pyrosequencing method was used to evaluate methylation of Alu, long interspersed nuclear elements-1 (LINE-1) and satellite-α (SAT-α) sequences in 77 untreated early-stage (Binet A) CLL patients. Peripheral B-cells from 7 healthy donors were used as controls. Methylation levels (median %5mC) were lower in B-CLLs compared with controls (21.4 vs. 25.9; 66.8 vs. 85.7; 84.0, vs. 88.2 for Alu, LINE-1 and SAT-α, respectively) (p < 0.001). Among CLL patients, a significant association was observed with 17p13.1 deletion (16.8 vs. 22.4; 51.2 vs. 68.5; 52.6 vs. 85.0, for Alu, LINE-1 and SAT-α) but not with other major genetic lesions, IgVH mutation status, CD38 or ZAP-70 expression. Follow-up analyses showed that lower SAT-α methylation levels appeared to be an independent prognostic marker significantly associated with shorter TFS. Our study extended previous limited evidences in methylation of repetitive sequences in CLL suggesting an important biological and clinical relevance in the disease.     

Effect of G-Quadruplex Polymorphism on the Recognition of Telomeric DNA by a Metal Complex

The physiological role(s) played by G-quadruplexes renders these ‘non-canonical’ DNA secondary structures interesting new targets for therapeutic intervention. In particular, the search for ligands for selective recognition and stabilization of G-quadruplex arrangements has led to a number of novel targeted agents. An interesting approach is represented by the use of metal-complexes, their binding to DNA being modulated by ligand and metal ion nature, and by complex stoichiometry. In this work we characterized thermodynamically and stereochemically the interactions of a Ni(II) bis-phenanthroline derivative with telomeric G-quadruplex sequences using calorimetric, chiroptical and NMR techniques. We employed three strictly related sequences based on the human telomeric repeat, namely Tel22, Tel26 and wtTel26, which assume distinct conformations in potassium containing solutions. We were able to monitor specific enthalpy/entropy changes according to the structural features of the target telomeric sequence and to dissect the binding process into distinct events. Interestingly, temperature effects turned out to be prominent both in terms of binding stoichiometry and ΔH/ΔS contributions, while the final G-quadruplex-metal complex architecture tended to merge for the examined sequences. These results underline the critical choice of experimental conditions and DNA sequence for practical use of thermodynamic data in the rational development of effective G-quadruplex binders.     

Conformation and Stability of Intramolecular Telomeric G-Quadruplexes: Sequence Effects in the Loops

Telomeres are guanine-rich sequences that protect the ends of chromosomes. These regions can fold into G-quadruplex structures and their stabilization by G-quadruplex ligands has been employed as an anticancer strategy. Genetic analysis in human telomeres revealed extensive allelic variation restricted to loop bases, indicating that the variant telomeric sequences maintain the ability to fold into G-quadruplex. To assess the effect of mutations in loop bases on G-quadruplex folding and stability, we performed a comprehensive analysis of mutant telomeric sequences by spectroscopic techniques, molecular dynamics simulations and gel electrophoresis. We found that when the first position in the loop was mutated from T to C or A the resulting structure adopted a less stable antiparallel topology; when the second position was mutated to C or A, lower thermal stability and no evident conformational change were observed; in contrast, substitution of the third position from A to C induced a more stable and original hybrid conformation, while mutation to T did not significantly affect G-quadruplex topology and stability. Our results indicate that allelic variations generate G-quadruplex telomeric structures with variable conformation and stability. This aspect needs to be taken into account when designing new potential anticancer molecules.     

Impaired response to influenza vaccine associated with persistent memory B cell depletion in non-Hodgkin's lymphoma patients treated with rituximab-containing regimens

Influenza vaccination is generally recommended for non-Hodgkin's lymphoma (NHL) patients, but no data are available about the activity of this vaccine after treatment with rituximab-containing regimens. We evaluated the humoral response to the trivalent seasonal influenza vaccine in a group of NHL patients in complete remission for ≥6 mo (median, 29 mo) after treatment with rituximab-containing regimens (n = 31) compared with age-matched healthy subjects (n = 34). B cell populations and incidence of influenza-like illness were also evaluated. For each viral strain, the response was significantly lower in patients compared with controls and was particularly poor in patients treated with fludarabine-based regimens. In the patient group, the response to vaccination did not fulfill the immunogenic criteria based on the European Committee for Medicinal Products for Human Use requirements. Among the patients, CD27(+) memory B cells were significantly reduced, and their reduction correlated with serum IgM levels and vaccine response. Episodes of influenza-like illness were recorded only in patients. These results showed that NHL patients treated with rituximab-containing regimens have persisting perturbations of B cell compartments and Ig synthesis and may be at particular risk for infection, even in long-standing complete remission.     

Differential Targeting of Unpaired Bases within Duplex DNA by the Natural Compound Clerocidin: A Valuable Tool to Dissect DNA Secondary Structure

Non-canonical DNA structures have been postulated to mediate protein-nucleic acid interactions and to function as intermediates in the generation of frame-shift mutations when errors in DNA replication occur, which result in a variety of diseases and cancers. Compounds capable of binding to non-canonical DNA conformations may thus have significant diagnostic and therapeutic potential. Clerocidin is a natural diterpenoid which has been shown to selectively react with single-stranded bases without targeting the double helix. Here we performed a comprehensive analysis on several non-canonical DNA secondary structures, namely mismatches, nicks, bulges, hairpins, with sequence variations in both the single-stranded region and the double-stranded flanking segment. By analysis of clerocidin reactivity, we were able to identify the exposed reactive residues which provided information on both the secondary structure and the accessibility of the non-paired sites. Mismatches longer than 1 base were necessary to be reached by clerocidin reactive groups, while 1-base nicks were promptly targeted by clerocidin; in hairpins, clerocidin reactivity increased with the length of the hairpin loop, while, interestingly, reactivity towards bulges reached a maximum in 3-base-long bulges and declined in longer bulges. Electrophoretic mobility shift analysis demonstrated that bulges longer than 3 bases (i.e. 5- and 7-bases) folded or stacked on the duplex region therefore being less accessible by the compound. Clerocidin thus represents a new valuable diagnostic tool to dissect DNA secondary structures.     

Low Percentage of KRAS Mutations Revealed by Locked Nucleic Acid Polymerase Chain Reaction: Implications for Treatment of Metastatic Colorectal Cancer

Metastatic colorectal cancer (mCRC) is frequently characterized by the presence of mutations of the KRAS oncogene, which are generally associated with a poor response to treatment with anti-epidermal growth factor receptor (anti-EGFR) monoclonal antibodies. With the methods currently used, a case is classified as KRAS-mutated when approximately 20% of the cells bear an activating KRAS mutation. These considerations raise the question of whether cells with a mutated KRAS can be found in mCRC cases classified as KRAS wild-type when more sensitive methods are used. In addition, the issue arises of whether these mCRC cases with low proportion of KRAS-mutated cells could account at least in part for the therapeutic failure of anti-EGFR therapies that occur in 40–60% of cases classified as KRAS wild type. In this study, we compared the classical assays with a very sensitive test, a locked nucleic acid (LNA) polymerase chain reaction (PCR), capable of detecting KRAS-mutated alleles at extremely low frequency (detection sensitivity limit 0.25% mutated DNA/wild-type DNA). By analyzing a cohort of 213 mCRC patients for KRAS mutations, we found a 20.6% discordance between the sequencing/TheraScreen methods and the LNA-PCR. Indeed, 44 mCRC patients initially considered KRAS wild type were reclassified as KRAS mutated by using the LNA-PCR test. These patients were more numerous among individuals displaying a clinical failure to anti-EGFR therapies. Failure to respond to these biological treatments occurred even in the absence of mutations in other EGFR pathway components such as BRAF.