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.     

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.     

MicroRNA-221/222 negatively regulates estrogen receptor alpha and is associated with tamoxifen resistance in breast cancer

A search for regulators of estrogen receptor alpha (ERalpha) expression has yielded a set of microRNAs (miRNAs) for which expression is specifically elevated in ERalpha-negative breast cancer. Here we show distinct expression of a panel of miRNAs between ERalpha-positive and ERalpha-negative breast cancer cell lines and primary tumors. Of the elevated miRNAs in ERalpha-negative cells, miR-221 and miR-222 directly interact with the 3'-untranslated region of ERalpha. Ectopic expression of miR-221 and miR-222 in MCF-7 and T47D cells resulted in a decrease in expression of ERalpha protein but not mRNA, whereas knockdown of miR-221 and miR-222 partially restored ERalpha in ERalpha protein-negative/mRNA-positive cells. Notably, miR-221- and/or miR-222-transfected MCF-7 and T47D cells became resistant to tamoxifen compared with vector-treated cells. Furthermore, knockdown of miR-221 and/or miR-222 sensitized MDA-MB-468 cells to tamoxifen-induced cell growth arrest and apoptosis. These findings indicate that miR-221 and miR-222 play a significant role in the regulation of ERalpha expression at the protein level and could be potential targets for restoring ERalpha expression and responding to antiestrogen therapy in a subset of breast cancers.     

Characterization of the pattern of alphas1- and beta-casein breakdown and release of a bioactive peptide by a cell envelope proteinase from Lactobacillus delbrueckii subsp. lactis CRL 581

The cell envelope-associated proteinases (CEPs) of the lactobacilli have key roles in bacterial nutrition and contribute to the development of the organoleptic properties of fermented milk products as well, as they can release bioactive health-beneficial peptides from milk proteins. The influence of the peptide supply, carbohydrate source, and osmolites on the CEP activity of the cheese starter Lactobacillus delbrueckii subsp. lactis CRL 581 was investigated. The CEP activity levels were controlled by the peptide content of the growth medium. The maximum activity was observed in a basal minimal defined medium, whereas in the presence of Casitone, Casamino Acids, or yeast extract, the synthesis of CEP was inhibited 99-, 70-, and 68-fold, respectively. The addition of specific di- or tripeptides containing branched-chain amino acids, such as leucylleucine, prolylleucine, leucylglycylglycine, or leucylproline, to the growth medium negatively affected CEP activity, whereas dipeptides without branched-chain amino acids had no effect on the enzyme's production. The carbon source and osmolites did not affect CEP activity. The CEP of L. delbrueckii subsp. lactis CRL 581 exhibited a mixed-type CEP(I/III) variant caseinolytic specificity. Mass-spectrometric screening of the main peptide peaks isolated by reverse-phase high-pressure liquid chromatography allowed the identification of 33 and 32 peptides in the alpha(s1)- and beta-casein hydrolysates, respectively. By characterizing the peptide sequence in these hydrolysates, a pattern of alpha(s1)- and beta-casein breakdown was defined and is reported herein, this being the first report for a CEP of L. delbrueckii subsp. lactis. In this pattern, a series of potentially bioactive peptides (antihypertensive and phosphopeptides) which are encrypted within the precursor protein could be visualized.