Characterization of Drosophila heterochromatin

A number of preliminary experiments have shown that the fluorescence pattern of Hoechst 33258, as opposed to that of quinacrine, varies with the concentration of dye. The metaphase chromosomes of D. melanogaster, D. simulans, D. virilis, D. texana, D. hydei and D. ezoana have therefore been stained with two concentrations of H 33258 (0.05 and 0.5 mug/ml in phosphate buffer at pH 7) and with a single concentration of quinacrine (0.5% in absolute alcohol). The three fluorescence patterns so obtained were shown to be somewhat different in some of the species and the coincide in others. All three stainings gave an excellent longitudinal differentiation of heterochromatin while euchromatin fluoresced homogeneously. Living ganglion cells of the six species mentioned above were treated with quinacrine and H 33258. Quinacrine induced a generalized lengthening and swelling of the chromosomes and H 33258 the decondensation of specific heterochromatic regions. A correlation of the base composition of the satellite DNAs contained in the heterochromatin of the species studied with the relative fluorescence and decondensation patterns showed that: 1) the extremely fluorochrome bright areas and those decondensed are present only in species containing AT rich satellite DNA; 2) the opposite is not true since some AT-rich satellite DNAs are neither fluorochrome bright nor decondensed; 3) there is no good correspondence between Hoechst bright areas and the decondensed ones. AT richness therefore appears to be a necessary but not sufficient condition both for bright fluorescence and decondensation. Some cytological evidence suggests that similarly AT rich satellite DNAs respond differently in fluorescence and decondensation because they are bound to different chromosomal proteins. A combination of the results of fluorescence and decondensation revealed at least 14 types of heterochromatin; 4-7 of which are simultaneously present in the same species. Since closely related species (i.e. D. melanogaster and D. simulans; D. virilis and D. texana) show marked differences in the heterochromatic types they contain, it can be suggested that within the genus Drosophila qualitative variations of heterochromatin have played an important role in speciation.     

Effect of bombesin-stimulated gastrin on gastric acid secretion in man

The effect of bombesin on gastrin release and gastric acid secretion was investigated in 10 healthy volunteers. Bombesin (0.6 μg · Kg^?1 · hr^?1) produced a significantly higher $\text{(}\text{p}\text{<}\text{0.001)}$ increase in plasma gastrin levels (86.7 11.1 pmo/1 than after a protein meal (39.6 ± 5.6 pmol1/1). The gastric acid secretory response to bombesin (12.1 ± 2.9 mEq · hr^?1) was however significantly lower $\text{(}\text{p}\text{<}\text{0.005)}$ than the maximal response produced by pentagostrin (20.9 ± 3.5 mEq · hr^?1) at the dose of 6 μg · Kg^?1. Atropine did not modify gastrin release induced by bombesin but significantly reduced gastric acid secretion $\text{(}\text{p}\text{<}\text{0.01)}$. From the data presented it may be hypothesized that less biologically active forms of gastrin and/or other peptides inhibiting the gastrin effect upon gastric acid secretion may be released by bombesin.     

The degree of acetylation of chitins by gas chromatography and infrared spectroscopy

Gas chromatography of a number of amines, alcohols and sulfur derivatives was carried out on chitin and partially deacetylated chitins as well as on chitosan. The retention time of methanol is proportional to the degree of acetylation, and therefore a method is proposed for the gas-chromatographic determination of the degree of acetylation of chitin/chitosan. The analysis of the infrared spectra of chitin/chitosan also permits one to determine the degree of acetylation by using the ratio of the bands 1550 and 2878 cm^?1.     

Ultrastructural aspects of fertile and sterile cysts of Echinococcus granulosus developed in hosts of different species

Bortoletti G. and Ferretti G. 1978. Ultrastructural aspects of fertile and sterile cysts of Echinococcus granulosus developed in hosts of different species. International Journal for Parasitology8: 421–431. Research was carried out on fertile and sterile cysts of Echinococcus granulosus taken from hosts of different species. Since the animals were bom and bred in Sardinia and had undergone spontaneous infection, this entails two reservations: firstly the stunted development of cysts in certain hosts, i.e. bovines, may be peculiar to a possible ‘Sardinian strain’ of E. granulosus; secondly, certain alterations in the germinal membrane may be due to parasite ageing. In some cases, the parasite may be dead despite the cyst appearing macroscopically normal because of the presence of the laminar layer.The germinal membrane ‘thrives’ to remarkably different degrees which do not, however, correlate with cyst fertility. The most thriving conditions are to be found in human cysts which are fertile; the germinal membrane may be thriving in pig cysts which are sterile; in sheep, the germinal membrane develops quite well and cysts are generally fertile; bovine cysts are generally sterile with stunted germinal membranes.There seems to be a direct correlation between cyst development and laminar layer thickness, whereas no correlations emerged with the organ in which cysts are located.     

Observations on some new and interesting Cryptophyceae

Three new varieties and two new combinations of marine Cryptophyceae are described: Proteomonas pseudobaltica comb, nov., P. pseudobaltica var. leonardiana var. nov., Pyrenomonas salina var. curvata var. nov., Rhinomonas reticulata var. atrorosea comb, et stat. nov., and R. reticulata var. compressa var. nov. Proteomonas is compared to the freshwater Cryptomonas marssonii. Planktonic specimens collected from the southern North Sea during the NERC North Sea Project 1988/89, tentatively identified as Cryptomonas acuta and Plagioselmis sp., are also examined. Characters having taxonomic significance at various levels include cell compression, periplast features, chloroplast number, nucleomorph position, and phycoerythrin type. Comments are made on cell shrinkage occuring during preparation for scanning electron microscopy (up to about 23%). The appearance af trie vestibular region from which the flagella emerge is also discussed. It is suggested that the term 'furrow' may encompass a variety of structures. Of these, only one appears to be non-artefactual; this seems to be taxonomically significant at most at the species level.     

Inhibition of the MEK/ERK signaling pathway by the novel antimetastatic agent NAMI-A down regulates c-myc gene expression and endothelial cell proliferation.

Imidazolium trans-imidazoledimethyl sulfoxide-tetrachlororuthenate (NAMI-A) is a novel ruthenium-containing experimental antimetastatic agent. Compelling evidence ascribes a pivotal role to endothelial cells in the orchestration of tumor angiogenesis and metastatic growth, suggesting antiangiogenic therapy as an attractive approach for anticancer treatment. In this context, activation of the mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) signaling pathway has been found fundamental in transducing extracellular stimuli that modulate a number of cellular process including cell proliferation, migration and invasion. Here we show that exposure of the transformed endothelial cell line ECV304 to NAMI-A significantly inhibited DNA synthesis, as well as the expression of the proliferating cell nuclear antigene (PCNA). These responses were associated with a marked down-regulation of ERK phosphorylation in serum-cultured cells. In addition, NAMI-A markedly reduced serum stimulated- and completely suppressed phorbol 12-myristate 13-acetate (PMA)-triggered MAPK/ERK kinase activity. NAMI-A was also able to inhibit the phosphorylation of MEK, the upstream activator of ERK, and, similar to both the protein kinase C (PKC) inhibitor GF109203X and the MAPK/ERK (MEK) inhibitor PD98059, it completely counteracted PMA-induced ERK phosphorylation. Finally, NAMI-A and PD98059 down regulated c-myc gene expression to the same extent in serum-cultured cells and dose-dependently counteracted, and ultimately abolished, the increase in c-myc gene expression elicited by PMA in serum-free cells. These results suggest that inhibition of MEK/ERK signaling by NAMI-A may have an important role in modulating c-myc gene expression and ECV304 proliferation.     

Synthesis of lipopeptides of the immunodominant epitope hMBP(83–99) containing amide or C-C bond linked hydrophobic chains for the study of T cell response

We previously demonstrated that the lipopeptide of the myelin basic protein (MBP) immunodominant epitope in Lewis rat Palm-GpMBP(74–85) (Gp: guinea pig), which induced experimental autoimmune encephalomyelitis in vivo strongly increased the T cell proliferative response in vitro. We extended this study to the human immunodominant epitope hMBP(83–99), synthesizing different lipophilic peptides bearing a hydrophobic chain linked through an amide or a C-C bond. To this aim, we developed a synthetic pathway for (±)-N-Fmoc-Ahd-OH (Ahd: 2-aminohexadecanoic acid) which was used to synthesize diastereomeric peptides which were successfully separated by reverse-phase high-performance liquid chromatography. MBP-specific T cell lines recognizing the immunodominant epitope hMBP(83–99) have been generated from patients affected by multiple sclerosis. Their proliferative response to the native peptide and to some lipoderivatives has been investigated. In contrast to the animal model, none of the investigated lipopeptides exhibited superagonist activity.     

Synthesis of lipopeptides of the immunodominant epitope hMBP(83–99) containing amide or C-C bond linked hydrophobic chains for the study of T cell response

Summary We previously demonstrated that the lipopeptide of the myelin basic protein (MBP) immunodominant epitope in Lewis rat Palm-GpMBP(74-85) (Gp: guinea pig), which induced experimental autoimmune encephalomyelitisin vivo strongly increased the T cell proliferative responsein vitro. We extended this study to the human immunodominant epitope hMBP(83-99), synthesizing different lipophilic peptides bearing a hydrophobic chain linked through an amide or a C-C bond. To this aim, we developed a synthetic pathway for (±)-N-Fmoc-Ahd-OH (Ahd: 2-aminohexadecanoic acid) which was used to synthesize diastereomeric peptides which were successfully separated by reverse-phase high-performance liquid chromatography. MBP-specific T cell lines recognizing the immunodominant epitope hMBP(83-99) have been generated from patients affected by multiple sclerosis. Their proliferative response to the native peptide and to some lipoderivatives has been investigated. In contrast to the animal model, none of the investigated lipopeptides exhibited ‘superagonist’ activity. Prof. L. Amaducci passed away on 11 January 1998. His memory will hearten those pursuing this research.     

A predictive study on the beginning of the pollen season for Gramineae andolea europaea L.

Summary On the basis of the results of seven years (1982–1988) of pollen and meteorological monitoring in the atmosphere of Perugia and Ascoli Piceno (central Italy) beginning of pollen season forecasts for Gramineae and Olea europaea L. are reported. The beginning of the pollen season for grass varied between May 2 nd and May 27th while for Olea it varied between May 26 th and June 23rd. By a statistical analysis of these data several significant correlations were found between the onset of the principal period of pollination and the air temperature in the preceding months and the number of ?heat units? required to flower. Utilizing multiple regressions a predictive method of the beginning of pollen season for both the taxa is reported.     

Induction of autophagic cell death by a novel molecule is increased by hypoxia

Adaptation to hypoxia through activation of the hypoxia inducible factor-1 (HIF-1) is crucial for tumor cells survival. Here we describe the antitumoral effects of the new molecule CR 3294 on tumor cells in the presence of hypoxia. Treatment of the breast carcinoma cell line MDA-MB-231 with CR 3294 in 1% O(2) resulted in an in vivo and in vitro inhibition of tumor growth. CR 3294 induced accumulation of autophagosomes in hypoxic MDA-MB-231 cells as assessed by both transmission electron microscopy (TEM) and the autophagic marker LC3-II. TEM analysis revealed the presence of invaginations of the cytoplasm into the nucleus. Autophagosomes were present in such invaginations. Moreover, CR 3294 inhibited both the DNA binding of HIF-1alpha and VEGF mRNA synthesis. Immunoprecipitation and immunofluorescence studies showed an interaction between LC3 and HIF-1alpha. We next detailed the effect of inhibitors and activators of autophagy on both HIF-1alpha and LC3. In particular, 3 methyladenine (3MA) and wortmannin, two macroautophagic inhibitors, prevented both the decrease of HIF-1alpha protein levels and LC3 processing in cells treated with CR 3294. Bafilomycin and leupeptin, inhibitors of lysosomes, prevented HIF-1alpha decrease without affecting LC3 processing. By contrast, treating hypoxic MDA-MB-231 cells with trifluoperazine (TFP) or serum withdrawal (SW), two activators of autophagy, diminished HIF-1alpha levels and stimulated LC3 processing. These results indicate that activation of the autophagic pathway in hypoxic cells by the new molecule CR 3294, as well as by TFP or SW, can have potentially important implications for cancer treatment.