The spatial control of Torso RTK activation: a C-terminal fragment of the Trunk protein acts as a signal for Torso receptor in the Drosophila embryo

Regulated activation of receptor tyrosine kinases depends on both the presence of the receptors at the cell surface and on the availability of their ligands. In Drosophila, the torso tyrosine kinase receptor is distributed along the surface of the embryo but it is only activated at the poles by a diffusible extracellular ligand generated at each pole that is trapped by the receptor, thereby impeding further diffusion. Although it is known that this signal depends on the activity of several genes, such as torso-like and trunk, it is still unclear how is generated. The identification of the signal responsible for the torso receptor activation is an essential step towards understanding the mechanism that regulates the local restriction of torso signalling. Here we report that a fragment containing the carboxy-terminal 108 amino acids of the trunk protein retains trunk activity and is sufficient to activate torso signalling. We also show that this fragment bypasses the requirements for the other genes involved in the activation of the torso receptor. These results suggest that a cleaved form of the trunk protein acts as a signal for the torso receptor. We therefore propose that the restricted activation of the torso receptor is defined by the spatial control of the proteolytic processing of the trunk protein.

Nd isotopes and water mixing phenomena in groundwaters from Palmottu (Finland)

The Palmottu uranium ore deposit, located within a granitic host rock in southern Finland, is an excellent setting for conducting analogue studies to assess radionuclide transport from the uranium deposit fractured crystalline host rock. In this context, Nd isotope ratios are used to establish the degree of water-rock interaction (WRI) and to clarify mixing processes within the groundwaters. Variations in Nd isotopes in selected water types from the Palmottu hydrosystem provide new information on the mixing history.

U-series disequilibria in a groundwater flow route as an indicator of uranium migration processes

U-series data relating to groundwater, fracture coatings and the adjoining rock matrix in a groundwater flow system at the Palmottu natural analogue site was examined. The aim was to obtain an experimental reference for migration modelling in a transport section defined within the flow system. The U-series reference obtained turned out to be a very useful tool for fine tuning the flow route and for migration mechanism considerations. The U-series data are well in line with other interpretations of the migration system.

Identification and quantitative determination of furanodiene, a heat-sensitive compound, in essential oil by 13C-NMR

A method based on 13C-NMR has been used as a tool for the identification and quantitative determination of two furanic sesquiterpenes: a heat-sensitive compound, furanodiene, and its rearrangement product, furanoelemene. Following a preliminary study using artificial mixtures which permitted the construction and verification of calibration curves for each compound, the method was used for the qualitative and quantitative analysis of furanodiene and furanoelemene in the essential oil of Smyrnium olusatrum.

Chemical variability of peel and leaf essential oils of 15 species of mandarins

Peel and leaf oils of 58 mandarin cultivars, belonging to 15 different species were obtained from fruits and leaves collected on mandarin-trees submitted to the same pedoclimatic and cultural conditions. Their chemical composition was investigated by capillary GC, GC/MS and 13C NMR and the results were submitted to a cluster analysis and a discriminant analysis. Three major chemotypes, limonene, limonene/gamma-terpinene and linalyl acetate/limonene, were distinguished for peel oils while three other chemotypes, sabinene/linalool, gamma-terpinene/linalool and methyl N-methylanthranilate, were observed for leaf oils.

The alternative migratory pathways of the Drosophila tracheal cells are associated with distinct subsets of mesodermal cells

The Drosophila tracheal system is a model for the study of the mechanisms that guide cell migration. The general conclusion from many studies is that migration of tracheal cells relies on directional cues provided by nearby cells. However, very little is known about which paths are followed by the migrating tracheal cells and what kind of interactions they establish to move in the appropriate direction. Here we analyze how tracheal cells migrate relative to their surroundings and which tissues participate in tracheal cell migration. We find that cells in different branches exploit different strategies for their migration; while some migrate through preexisting grooves, others make their way through homogeneous cell populations. We also find that alternative migratory pathways of tracheal cells are associated with distinct subsets of mesodermal cells and propose a model for the allocation of groups of tracheal cells to different branches. These results show how adjacent tissues influence morphogenesis of the tracheal system and offer a model for understanding how organ formation is determined by its genetic program and by the surrounding topological constraints.

Changes in the structure and ultrastructure of the intestine of Spadella cephaloptera (Chaetognatha) during feeding and starvation experiments

Ultrastructural changes in the intestinal epithelium of fed and starved specimens of Spadella cephaloptera are described. Animals were maintained in a circulating natural sea water system and fed with Artemia salina nauplii. After a period of acclimation, they were individually isolated, deprived of food for 24 h and submitted to controlled feeding experiments. The absorption develop in the intestinal absorptive cells (A-cells) 5 min after the ingestion of prey and consist in the formation of endocytotic vesicles and endosome-like vacuoles. During the following steps up to 10 h, a second type of digestive vacuole containing electron-dense material, and probably corresponding to a lysosome-like compartment, appears. Throughout this time, the vacuoles progressively arrange in columns, the youngest at the top and the oldest at the bottom of the A-cells. In addition, large lipid inclusions appear in the apical cytoplasm. The ultrastructural changes of the intestinal secretory cells (S-cells) is less marked, but the number of granules largely diminishes during the first 30 min after the ingestion of prey. In starved specimens, major changes in A-cells occur between the sixth and tenth day of starvation and consist in the increase of endosome-like vacuoles. Lysosome-like vacuoles containing dense material are not observed. At the same time, necrosis features are evident in S-cells. After 30 days of starvation, necrosis features are observed in the totality of the intestinal epithelium and the specimens die few days later.

Antimicrobial activity and chemical composition of the bark oil of Croton stellulifer, an endemic species from S. Tomé e Príncipe

The composition and the antimicrobial activity of the bark oil of Croton stellulifer, an endemic and rare species of these islands (S. Tomé and Príncipe) are reported. Analysis was carried out by GC, GC/MS and 13C-NMR. The major constituents were alpha-phellandrene (15.4-18.6%), p-cymene (14.4-17.7%), linalool (12.0-12.6%) and alpha-pinene (8.1-9.1%). Kessane, a sesquiterpenoid oxide, not yet reported in the genus Croton, was identified by NMR. The essential oil of C. stellulifer was active against both bacterial and fungal strains, except Aspergillus niger.

The GAGA factor of Drosophila interacts with SAP18, a Sin3-associated polypeptide

SAP18, a polypeptide associated with the Sin3-HDAC co-repressor complex, was identified in a yeast two-hybrid screen as capable of interacting with the Drosophila GAGA factor. The interaction was confirmed in vitro by glutathione S-transferase pull-down assays using recombinant proteins and crude SL2 nuclear extracts. The first 245 residues of GAGA, including the POZ domain, are necessary and sufficient to bind dSAP18. In polytene chromosomes, dSAP18 and GAGA co-localize at a few discrete sites and, in particular, at the bithorax complex where GAGA binds some silenced polycomb response elements. When the dSAP18 dose is reduced, flies heterozygous for the GAGA mutation Trl67 show the homeotic transformation of segment A6 into A5, indicating that GAGA-dSAP18 interaction contributes to the functional regulation of the iab-6 element of the bithorax complex. These results suggest that, through recruitment of the Sin3-HDAC complex, GAGA might contribute to the regulation of homeotic gene expression.

The 3-month clinical response to intravesical therapy as a predictive factor for progression in patients with high risk superficial bladder cancer

PURPOSE

We analyzed the 3-month clinical response to intravesical therapy as a factor predictive of progression in patients with high risk superficial bladder cancer.

MATERIAL AND METHODS

We evaluated 191 patients with high risk superficial bladder cancer, 111 with secondary or associated bladder carcinoma in situ and 80 with stage T1 grade 3 disease who were treated with intravesical therapy. We considered only clinically complete and no responses at the 3-month endoscopic study. To determine the predictive value of the 3-month clinical response we differentiated progression into superficial and invasive types.

RESULTS

At a median followup of 73 months 91 patients (47.6%) had progression, which was superficial in 48 (25. 1%) and invasive in 43 (22.5%). Invasive progression was associated with significantly higher cause specific mortality than superficial progression (p = 0). In the latter cases cause specific mortality was higher than in those without progression (p = 0.001). Although cystectomy significantly decreased the cause specific mortality rate in patients with invasive progression (p = 0.0001), this rate was high at 46.3%. Univariate and multivariate analyses revealed that the 3-month clinical response was a significant predictive factor for progression. Moreover, stratifying this variable showed that this response was the only independent factor predictive of invasive progression in cases of no response with stage T1 grade 3 tumor, bladder carcinoma in situ, or prostate mucosa or duct involvement (p = 0). In our series 41 patients (21.5%) did not respond after intravesical therapy at the 3-month evaluation, including 29 with stage T1 grade 3 disease, bladder carcinoma in situ, or prostate mucosa or duct involvement. Progression in 24 of these 29 patients (82.3%) was classified as invasive in 21 (73.6%).

CONCLUSIONS

Invasive progression threatens the cause specific survival of patients with high risk superficial bladder cancer even when cystectomy is performed. The 3-month clinical response was an excellent predictive factor for invasive progression. Early cystectomy should be considered when stage T1 grade 3 tumor, bladder carcinoma in situ, or prostate mucosa or duct involvement is present at the 3-month clinical evaluation.

Cross-regulatory interactions among tracheal genes support a co-operative model for the induction of tracheal fates in the Drosophila embryo

The Drosophila tracheal system arises from clusters of ectodermal cells that invaginate and migrate to originate a network of epithelial tubes. Genetic analyses have identified several genes that are specifically expressed in the tracheal cells and are required for tracheal development. Among them, trachealess (trh) is able to induce ectopic tracheal pits and therefore it has been suggested that it would act as an inducer of tracheal cell fates; however, this capacity appears to be spatially restricted. Here we analyze the expression of the tracheal specific genes in the early steps of tracheal development and their cross-interactions. We find that there is a set of primary genes including trh and ventral veinless (vvl) whose expression does not depend on any other tracheal gene and a set of downstream genes whose expression requires different combinations of the primary genes. We also find that the combined expression of primary genes is sufficient to induce some downstream genes but not others. These results indicate that there is not a single master gene responsible for the appropriate expression of the tracheal genes and support a model where tracheal cell fates are induced by the co-operation of several factors rather than by the activity of a single tracheal inducer.

Femtosecond observation of benzyne intermediates in a molecular beam: Bergman rearrangement in the isolated molecule

In this communication, we report our femtosecond real-time observation of the dynamics for the three didehydrobenzene molecules (p-, m-, and o-benzyne) generated from 1,4-, 1,3-, and 1, 2-dibromobenzene, respectively, in a molecular beam, by using femtosecond time-resolved mass spectrometry. The time required for the first and the second C-Br bond breakage is less than 100 fs; the benzyne molecules are produced within 100 fs and then decay with a lifetime of 400 ps or more. Density functional theory and high-level ab initio calculations are also reported herein to elucidate the energetics along the reaction path. We discuss the dynamics and possible reaction mechanisms for the disappearance of benzyne intermediates. Our effort focuses on the isolated molecule dynamics of the three isomers on the femtosecond time scale.

Relief of gene repression by torso RTK signaling: role of capicua in Drosophila terminal and dorsoventral patterning

Differentiation of the embryonic termini in Drosophila depends on signaling by the Tor RTK, which induces terminal gene expression by inactivating at the embryonic poles a uniformly distributed repressor activity that involves the Gro corepressor. Here, we identify a new gene, cic, that acts as a repressor of terminal genes regulated by the Tor pathway. cic also mediates repression along the dorsoventral axis, a process that requires the Dorsal morphogen and Gro, and which is also inhibited by Tor signaling at the termini. cic encodes an HMG-box transcription factor that interacts with Gro in vitro. We present evidence that Tor signaling regulates terminal patterning by inactivating Cic at the embryo poles. cic has been evolutionarily conserved, suggesting that Cic-like proteins may act as repressors regulated by RTK signaling in other organisms.

VASA mediates translation through interaction with a Drosophila yIF2 homolog

The Drosophila gene vasa (vas) encodes an RNA-binding protein required for embryonic patterning and germ cell specification. In vas mutants, translation of several germline mRNAs is reduced. Here we show that VAS interacts directly with the Drosophila homolog of yeast translation initiation factor 2, encoded by a novel gene, dIF2. Embryos produced by vas/+; dIF2/+ females have pattern defects and fewer germline progenitor cells, indicating a functional interaction between endogenous vas and dIF2 activities. Mutations in other translation initiation factors do not enhance the vas phenotype, suggesting that dIF2 has a particular role in germ plasm function. We conclude that VAS regulates translation of germline mRNAs by specific interaction with dIF2, an essential factor conserved from bacteria to humans.

Rapid screening for organochlorine and organophosphorus pesticides in milk using C18 and graphitized carbon black solid phase extraction cleanup

A rapid, multiresidue, solid phase extraction (SPE) technique for the isolation and gas chromatographic determination of organochlorine and moderately polar organophosphorus pesticide residues in milk is described. Milk is sonicated with an acetonitrile-acetone-methanol mixture and centrifuged. The supernatant is subjected to a cleanup using both C18 and graphitized carbon black SPE columns. The pesticide residues are determined by gas chromatography with electron capture and flame photometric detection. The method required minimal volumes of solvent and resulted in the production of minimal volumes of hazardous waste.

Effectiveness of a single immediate mitomycin C instillation in patients with low risk superficial bladder cancer: short and long-term followup

PURPOSE

We analyze the impact of a single mitomycin C instillation in patients with low risk superficial bladder cancer with short and long-term followup.

MATERIALS AND METHODS

A total of 131 patients with low risk superficial bladder cancer were included in a prospective randomized controlled trial. All patients had a 3 cm or less single, papillary, primary or recurrent tumor and were disease-free for more than 1 year. Patients with muscular invasion, G3 tumor or bladder carcinoma in situ on pathological examination were excluded from study. The tumor was completely resected before patients were randomized into 2 arms of no further treatment (control group) and a single immediate instillation of 30 mg mitomycin C (mitomycin C group). Recurrences were considered early within the first 2 years of followup.

RESULTS

At 24-month followup the recurrence-free interval was significantly increased, and recurrence, and recurrence and tumor per year rates were decreased in the mitomycin C compared to the control group. However, at long-term followup these differences were not statistically significant and the recurrence-free interval curves were parallel. A shorter hospital stay and catheterization period were noted in the mitomycin C group compared to the control group, which were not significant. Early recurrences were concentrated in the first year in the control but not in the mitomycin C group. A significant relationship between early and late recurrences was found in the mitomycin C but not in the control group.

CONCLUSIONS

Our analysis confirms the positive effect of a single immediate mitomycin C instillation in patients with low risk superficial bladder cancer. This benefit is limited to early recurrence and is not maintained with long-term followup. Thus, this approach is an alternative to observation or endovesical chemotherapy. Our study also suggests that cell implantation as a mechanism of early recurrence can be controlled with a single mitomycin C instillation.

EGF signalling regulates cell invagination as well as cell migration during formation of tracheal system in Drosophila

The Drosophila tracheal system is a network of epithelial tubes that arises from the tracheal placodes, lateral clusters of ectodermal cells in ten embryonic segments. The cells of each cluster invaginate and subsequent formation of the tracheal tree occurs by cell migration and fusion of tracheal branches, without cell division. The combined action of the Decapentaplegic (Dpp), Epidermal growth factor (EGF) and breathless/branchless pathways are thought to be responsible for the pattern of tracheal branches. We ask how these transduction pathways regulate cell migration and we analyse the consequences on cell behaviour of the Dpp and EGF pathways. We find that rhomboid (rho) mutant embryos display defects not only in tracheal cell migration but also in tracheal cell invagination unveiling a new role for EGF signalling in the formation of the tracheal system. These results indicate that the transduction pathways that control tracheal cell migration are active in different steps of tracheal formation, beginning at invagination. We discuss how the consecutive steps of tracheal morphogenesis might affect the final branching pattern.

Composition of the essential oils of Ocimum canum, O. gratissimum and O. minimum

The essential oils of OCIMUM CANUM, O. GRATISSIMUM and O. MINIMUM grown in S. Tomé, where they are used in Traditional Medicine mainly as febrifuge and for the treatment of respiratory diseases, were investigated. The essential oils were obtained from the aerial parts by hydrodistillation and subsequently analysed by GC, GC-MS and (13)C-NMR. (13)C-NMR SPECTROSCOPY proved to be an important tool, which can be very useful in the identification of most of the constituents. Major compounds in the volatile oil of O. GROTISSIMUM were thymol (48.1%) and P-cymene (12.5%). The essential oil of O. CANUM was characterized by its high content of TRANS-METHYL cinnamate (79.7%), whereas the most important oil constituent of O. MINIMUM was linalool (52.7%).

Role of the conserved C-terminal region of thyroid hormone receptor-alpha in ligand-dependent transcriptional activation

The ligand binding domain (LBD) of thyroid hormone (T3) receptors contains subdomains that participate in transcriptional activation, hormone-relieved repression and dimerization. A sequence conserved within the nuclear receptor superfamily is found at positions 397-405 of the 408-amino acid chicken T3 receptor-alpha (cTR alpha) and is deleted in the related avian v-erbA. Since v-erbA exhibits compromised ligand binding and transcriptional activation, this conserved region may play a role in ligand-dependent transcriptional activation. Transfections reveal that cTR alpha(1-392) and site-directed mutants cTR alpha(L398R) and cTR alpha(F399E) are inactive, while cTR alpha(1-403) displays reduced ligand-dependent transcriptional activity. The loss of transcriptional activity in cTR alpha(1-392) is not caused by impaired DNA binding or receptor dimer formation. Proteolytic protection assays reveal that both transcriptionally active and inactive cTR alpha derivatives undergo T3-mediated conformational changes. Gal4 chimeras containing the final 16, 35 or 44 amino acids of cTR alpha indicate that the conserved C-terminal region does not function as an independent transactivation domain. Our results are consistent with a model in which ligand plays a structural role to position the conserved C-terminal regions of cTR alpha and related receptors in a transcriptionally active conformation.

Feasibility of transurethral resection for muscle infiltrating carcinoma of the bladder: long-term followup of a prospective study

PURPOSE

We analyzed the long-term results of radical transurethral resection for the treatment of a large series of patients with muscle infiltrating bladder cancer entered into a prospective study to determine progression predictive factors.

MATERIALS AND METHODS

The study included 133 patients with invasive bladder cancer treated by radical transurethral resection who had negative biopsies of the muscle layer of the tumor bed. Followup was more than 5 years for all subjects and more than 10 years in 59 (44.4%). A comparative nonrandomized study was performed of a control group of 76 patients with invasive pathological stage pT2-3a, N0-3 bladder cancer treated by cystectomy. In those patients treated by radical transurethral resection univariate and multivariate analyses were performed to establish clinical progression predictive factors.

RESULTS

At 5 and 10 years of followup cause specific survival rates were 80.5 and 74.5%, and bladder preservation rates were 82.7 and 79.6%, respectively. No significant difference was noted in terms of cause specific survival, with respect to the control group. The initial presence of associated bladder carcinoma in situ was the only independent progression predictive factor.

CONCLUSIONS

For patients with invasive bladder cancer radical transurethral resection is justified when the tumor is clinically limited to the muscular layer and when all biopsies of the periphery and depth of the tumor bed show muscular tissue negative for tumor cells. Patients with initial associated bladder carcinoma in situ should not be excluded from this treatment but endovesical bacillus Calmette-Guerin immunotherapy should be administered and a closer followup is recommended.

[Partial pericardectomy using videothoracoscopy]

OBJECTIVE

The aim of this study is to assess the validity of videothoracoscopy in the treatment of chronic pericardial effusions.

STUDY PATIENTS

We studied 13 consecutive patients with chronic pericardial effusions and an indication for surgical treatment. The patients, 10 female and 3 male, had a mean age of 48 years (21-72 years). Eleven patients had recurrent pericardial effusion and two patients had anterior mediastinal masses of unknown etiology and a large pericardial effusion.

METHODS

A videothoracoscopy was performed in every patient, under general anesthesia with a double-lumen endotracheal tube. The thoracic cavity was inspected, the pericardial effusion was drained and a partial pericardectomy was performed.

RESULTS

There was no postoperative mortality or morbidity. Average duration of postoperative thoracic drain and postoperative stay were, 1.2 and 2.4 days respectively. Follow-up ranged from 1 to 48 months (mean 23.3 months). One patient died due to progression of his malignant disease. There were no cases of recurrent pericardial effusions.

CONCLUSIONS

Video assisted pericardectomy is a safe technique that should be considered in the treatment of chronic pericardial effusions.

Dissecting the mechanism of torso receptor activation

Regulated activation of receptor tyrosine kinases depends both on the presence of the receptors at the cell surface and on the availability of their ligands. In Drosophila the torso (tor) tyrosine kinase receptor is distributed along the surface of the embryo but it is only activated at the poles by a diffusible extracellular ligand generated at each pole which is trapped by the receptor, thereby impeding further diffusion. However, it is not well understood how this signal is generated, although it is known to depend on the activity of many genes such as torso-like (tsl) and trunk (trk). To further investigate the mechanism involved in the local activation of the tor receptor we have altered the normal expression of the tsl protein by generating females in which the tsl gene is expressed in the oocyte under the control of the tor promoter rather than in the ovarian follicle cells. Analysis of the phenotypes generated by this hybrid gene and its interactions with mutations in other genes in the pathway has enabled us to further dissect the mechanism of tor receptor activation and to define more precisely the role of the different genes acting in this process.