The structure and dynamics of ring chromosomes in human neoplastic and non-neoplastic cells

Acquired ring chromosomes have been found in most types of human neoplasia, with a frequency approaching 10% in malignant mesenchymal tumours. In this study, the composition and dynamics of ring chromosomes were analysed in eight cases of acute myelogenous leukaemia, 17 solid tumours, and five cases with constitutional rings. Chromosomal banding and fluorescence in situ hybridisation were performed to determine the content and the structural heterogeneity of the rings. Telomeric repeats were detected using peptide nucleic acid probes or primed in situ labelling, whereas centromeric activity was evaluated by detection of kinetochore proteins. Mitotic instability was assessed by the frequency of anaphase bridges. The results suggest that human ring chromosomes can be structurally and functionally divided into two categories. In the first of these, size variation is minimal and rearrangement at cell division is uncommon. The majority of such rings contain subtelomeric sequences. Constitutional ring chromosomes and most rings in leukaemias belong to this group, whereas only a few mesenchymal tumours exhibit rings of this type. The second category consists of rings with amplified sequences, primarily from chromosome 12, characteristically occurring in atypical lipomatous tumours and other subtypes of low or borderline malignant mesenchymal neoplasms. Variation in size and number is extensive, and breakage-fusion-bridge events occur at a high frequency. Abnormalities in pericentromeric sequences are common and, in some cases, kinetochores assemble in the absence of alphoid DNA. We conclude that it is not only the ring structure per se or the neoplastic nature of the host cell that determines ring instability, but probably also the functional role of the genes carried in the ring. Received: 24 November 1998 / Accepted: 18 January 1999     

Stem cell factor is localized in, released from, and cleaved by human mast cells.

Stem cell factor (SCF) is the most important cytokine regulating human mast cell growth and functions. The immunogold technique showed SCF in the secretory granules of skin mast cells and in lung parenchymal mast cells (HLMC). Immunoreactive SCF (iSCF) was detected in cell lysates of HLMC, but not in basophils; iSCF and histamine were detected in supernatants of HLMC 3 min after challenge with anti-FcepsilonRI or anti-IgE, and iSCF in supernatants rapidly declined after 30 min, whereas histamine remained unchanged for 120 min. HPLC and electrospray mass spectrometry (ES/MS) analysis of recombinant human SCF1-166 (18,656. 9 +/- 0.9 Da) treated with chymase showed a polypeptide of 17,977.1 +/- 0.6 Da and a minor component of 697.4 +/- 0.1 Da generated by specific cleavage at Phe159. SCF1-166 and SCF1-159 similarly activated HLMC, potentiated anti-IgE-induced activation of these cells, and stimulated HLMC chemotaxis. SCF159-166 had no effect on mast cells. Western blot analysis of supernatants of anti-IgE-activated HLMC incubated with recombinant human SCF1-166 showed that SCF1-166 was rapidly cleaved to SCF1-159 and SCF1-144. Experiments with supernatants of anti-IgE-activated HLMC incubated with SCF1-166 yielded similar results. In conclusion, SCF is stored in mast cell secretory granules and is immunologically released by human mast cells. SCF1-166 is rapidly and specifically cleaved to SCF1-159 by chymase, which retains its biological effect on mast cells. SCF is also cleaved by other proteases to several SCF species whose possible biological activities remain to be established.     

Chemical Composition,Antibacterial, Antibiofilm and Synergistic Properties of Essential Oils from Eucalyptus globulus Labill. and Seven Mediterranean Aromatic Plants

Essential oils (EOs) from Eucalyptus globulus Labill . ssp. globulus and from Mediterranean autochthonous aromatic plants – Thymus mastichina L., Mentha pulegium L., Rosmarinus officinalis L., Calamintha nepeta (L.) Savi ssp. nepeta, Cistus ladanifer L., Foeniculum vulgare L., Dittrichia viscosa (L.) Greuter ssp. viscosa – were extracted by hydrodistillation and characterized by GC‐FID and NMR spectroscopy. EOs were evaluated for antimicrobial properties against several bacterial strains, using diverse methods, namely, the agar disc‐diffusion method, the microdilution method, the crystal violet assay and the Live/Dead staining for assessment of biofilm formation. Potential synergy was assessed by a checkerboard method. EOs of R. officinalis and C. ladanifer showed a predominance in monoterpene hydrocarbons (> 60%); EOs of C. nepeta, M. pulegium, T. mastichina, E. globulus and F. vulgare were rich in oxygenated monoterpenes (62 – 96%) whereas EO of D. viscosa was mainly composed of oxygenated sesquiterpenes (54%). All EOs showed antimicrobial activity; M. pulegium and E. globulus generally had the strongest antimicrobial activity. EO of C. nepeta was the most promising in hampering the biofilm formation. The combinations D. viscosa/C. nepeta and E. globulus/T. mastichina were synergistic against Staphylococcus aureus. These results support the notion that EOs from the aromatic plants herein reported should be further explored as potential pharmaceuticals and/or food preservatives.     

Chromosomal distribution of interstitial telomeric sequences as signs of evolution through chromosome fusion in six species of the giant water bugs (Hemiptera,Belostoma)

Tandem arrays of TTAGG repeats show a highly conserved location at the telomeres across the phylogenetic tree of arthropods. In giant water bugs Belostoma, the chromosome number changed during speciation by fragmentation of the single ancestral X chromosome, resulting in a multiple sex chromosome system. Several autosome–autosome fusions and a fusion between the sex chromosome pair and an autosome pair resulted in the reduced number in several species. We mapped the distribution of telomeric sequences and interstitial telomeric sequences (ITSs) in Belostoma candidulum (2n = 12 + XY/XX; male/female), B. dentatum (2n = 26 + X₁X₂Y/X₁X₁X₂X₂), B. elegans (2n = 26 + X₁X₂Y/X₁X₁X₂X₂), B. elongatum (2n = 26 + X₁X₂Y/X₁X₁X₂X₂), B. micantulum (2n = 14 + XY/XX), and B. oxyurum (2n = 6 + XY/XX) by FISH with the (TTAGG)_n probes. Hybridization signals confirmed the presence of TTAGG repeats in the telomeres of all species examined. The three species with reduced chromosome numbers showed additional hybridization signals in interstitial positions, indicating the occurrence of ITS. From the comparison of all species here analyzed, we observed inverse relationships between chromosome number and chromosome size, and between presence/absence of ITS and chromosome number. The ITS distribution between these closely related species supports the hypothesis that several telomere–telomere fusions of the chromosomes from an ancestral diploid chromosome number 2n = 26 + XY/XX played a major role in the karyotype evolution of Belostoma. Consequently, our study provide valuable features that can be used to understand the karyotype evolution, may contribute to a better understanding of taxonomic relationships, and also elucidate the high plasticity of nuclear genomes at the chromosomal level during the speciation processes.     

Immobilization of <Emphasis Type="Italic">Streptomyces</Emphasis> phospholipase D on a Dowex macroporous resin

The immobilization of phospholipase D produced by Streptomyces sp. YU100 was evaluated to see it would be practical for industrial applications. To accomplish this, the purified enzyme, which contained 53 unit/mg of protein, was subjected to immobilization on various matrices. When immobilization supports including calcium alginate gel, polyacrylamide gel, and macroporous resin were evaluated, the highest enzyme retention ratio (> 42%) was observed on a Dowex MSA-2 macro-porous resin. This may have occurred as a result of the ability of the hydrophobic domain of phospholipase D to interact with the polystyrene backbone of the resin, as well as the ability of the dimethylethanolamine group of the MSA-2 resin to retain the enzyme by forming hydrogen bonds with the acidic residues of the enzyme. Upon the operation of a reactor packed with enzyme that had been immobilized on a Dowex MSA-2 resin, greater than 80% of the initial enzyme activity was retained for 16 days. During the reaction, phosphatidylcholine became bound to the immobilized resin and interfered with the enzyme reaction, therefore, the resin was washed with ethyl ether every 2 h. A process for recovering excessive l-serine from phospholipids using the Dowex MR-3 resin was designed, and the separated l -serine was employed again after replacing the amount that was used.     

Secondary metabolites from the aerial parts of Salvia palaestina Bentham

Three sesterterpenes (1-3), one triterpene (4) and five diterpenes (5-9) were isolated from the aerial parts of Salvia palaestina Bentham (Lamiaceae), together with two sesquiterpenes, 10 known diterpenes, three triterpenes, and rosmarinic acid. Their structural elucidation was accomplished by extensive spectroscopic methods including 1D ((1)H, (13)C, (13)C DEPT, TOCSY, NOESY) and 2D NMR experiments (DQF-COSY, HSQC, HMBC, ROESY) as well as ESIMS analysis and chemical analysis.     

Localization patterns of fibroblast growth factor 1 and its receptors FGFR1 and FGFR2 in postnatal mouse retina

Fibroblast growth factors (FGFs) exert basic functions both during embryonic development and in the adult. The expression of FGFs and their receptors has been reported in mammalian retinas, although information on the organization of the FGF system is still incomplete. Here, we report a detailed double-label immunohistochemical investigation of the localization patterns of FGF1 and its receptors FGFR1 and FGFR2 in adult and early postnatal mouse retinas. In adult retinas, FGF1 is localized to ganglion cells, horizontal cells, and photoreceptor inner and outer segments. FGFR1 is found in ganglion cells and Müller cells, whereas FGFR2 is primarily located in ganglion cells, the nuclei of Müller cells, and glycine-containing amacrine cells. During postnatal development, the patterns of FGF1, FGFR1, and FGFR2 immunostaining are similar to those in the adult, although transient FGF1-expressing cells have been detected in the proximal inner nuclear layer before eye opening. These patterns are consistent with a major involvement of FGF1, FGFR1, and FGFR2 in ganglion cell maturation (during development) and survival (in the adult). Moreover, FGF1 may affect amacrine cell development, whereas Müller cells appear to be regulated via both FGFR1 and FGFR2 throughout postnatal life. In immature retinas, large numbers of amacrine cells, including those containing calbindin and glycine, display both FGF1 and FGFR2 immunoreactivities in their nuclei, suggesting an action of FGF1 on FGFR2 leading to the maturation of these amacrine cells during a restricted period of postnatal development. This work was supported by funding from the Italian Ministry of Education.     

东亚飞蝗hunchback基因在卵子形成和胚胎发育过程中的原位表达

hb（hunchback）基因是昆虫胚胎前后轴模式形成的关键基因．对东亚飞蝗（Locusta migratoria manilensis,Meyen）hb基因的功能已有报道,但其表达模式还不清楚．为了研究胁基因在东亚飞蝗卵子形成和胚胎发育过程中的时空表达情况,本研究采用免疫组化方法在蛋白质水平上检测了hb基因的时空表达模式．在卵子形成过程中,hb基因局限在卵细胞核区中表达,随着卵子的发育逐渐移至卵细胞的后端;卵受精后,核区里的Hb蛋白向外扩散,在卵后端形成浓度梯度;胚盘期,hb基因在胚盘中央呈带状表达;胚盘分化为原头和原躯干后,表达条带变宽,并呈现出梯度表达,该表达区域将形成颌、胸部的部分体节;随着腹节开始形成,hb基因在颌胸部的表达逐渐减弱,而在腹部后端的“生长区”表达,并呈现出不连续性．经比较,hb易基因在昆虫颌胸部的表达较为保守,而在卵子形成过程中和腹部的表达具有较大的变异性．与黑腹果蝇等长胚带昆虫相比,东亚飞蝗hb基因在体节形成的基因级联调控中具有更重要、更直接的调控作用．