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T Volpe

Publications and source records attributed to T Volpe.

15 recordsLinked to original sources
PubMed2001

Whi3 binds the mRNA of the G1 cyclin CLN3 to modulate cell fate in budding yeast.

Eukaryotic cells commit in G1 to a new mitotic cycle or to diverse differentiation processes. Here we show that Whi3 is a negative regulator of Cln3, a G1 cyclin that promotes transcription of many genes to trigger the G1/S transition in budding yeast. Whi3 contains an RNA-recognition motif that specifically binds the CLN3 mRNA, with no obvious effects on Cln3 levels, and localizes the CLN3 mRNA into discrete cytoplasmic foci. This is the first indication that G1 events may be regulated by locally restricting the synthesis of a cyclin. Moreover, Whi3 is also required for restraining Cln3 function in meiosis, filamentation, and mating, thus playing a key role in cell fate determination in budding yeast.

Amino Acid Motifs↗
PubMed2001

Isolation and characterization of WHI3, a size-control gene of Saccharomyces cerevisiae.

WHI3 is a gene affecting size control and cell cycle in the yeast Saccharomyces cerevisiae. The whi3 mutant has small cells, while extra doses of WHI3 produce large cells, and a large excess of WHI3 produces a lethal arrest in G1 phase. WHI3 seems to be a dose-dependent inhibitor of Start. Whi3 and its partially redundant homolog Whi4 have an RNA-binding domain, and mutagenesis experiments indicate that this RNA-binding domain is essential for Whi3 function. CLN3-1 whi3 cells are extremely small, nearly sterile, and largely nonresponsive to mating factor. Fertility is restored by deletion of CLN2, suggesting that whi3 cells may have abnormally high levels of CLN2 function.

Amino Acid Sequence↗
PubMed2000

Two yeast forkhead genes regulate the cell cycle and pseudohyphal growth.

There are about 800 genes in Saccharomyces cerevisiae whose transcription is cell-cycle regulated. Some of these form clusters of co-regulated genes. The 'CLB2' cluster contains 33 genes whose transcription peaks early in mitosis, including CLB1, CLB2, SWI5, ACE2, CDC5, CDC20 and other genes important for mitosis. Here we find that the genes in this cluster lose their cell cycle regulation in a mutant that lacks two forkhead transcription factors, Fkh1 and Fkh2. Fkh2 protein is associated with the promoters of CLB2, SWI5 and other genes of the cluster. These results indicate that Fkh proteins are transcription factors for the CLB2 cluster. The fkh1 fkh2 mutant also displays aberrant regulation of the 'SIC1' cluster, whose member genes are expressed in the M-G1 interval and are involved in mitotic exit. This aberrant regulation may be due to aberrant expression of the transcription factors Swi5 and Ace2, which are members of the CLB2 cluster and controllers of the SIC1 cluster. Thus, a cascade of transcription factors operates late in the cell cycle. Finally, the fkh1 fkh2 mutant displays a constitutive pseudohyphal morphology, indicating that Fkh1 and Fkh2 may help control the switch to this mode of growth.

Binding Sites↗
PubMed1997

Proteome studies of Saccharomyces cerevisiae: identification and characterization of abundant proteins.

Two-dimensional (2-D) gel electrophoresis can now be coupled with protein identification techniques and genome sequence information for direct detection, identification, and characterization of large numbers of proteins from microbial organisms. 2-D electrophoresis, and new protein identification techniques such as amino acid composition, are proteome research techniques in that they allow direct characterization of many proteins at the same time. Another new tool important for yeast proteome research is the Yeast Protein Database (YPD), which provides the sequence-derived protein properties needed for spot identification and tabulations of the currently known properties of the yeast proteins. Studies presented here extend the yeast 2-D protein map to 169 identified spots based upon the recent completion of the yeast genome sequence, and they show that methods of spot identification based on predicted isoelectric point, predicted molecular mass, and determination of partial amino acid composition from radiolabeled gels are powerful enough for the identification of at least 80% of the spots representing abundant proteins. Comparison of proteins predicted by YPD to be detectable on 2-D gels based on calculated molecular mass, isoelectric point and codon bias (a predictor of abundance) with proteins identified in this study suggests that many glycoproteins and integral membrane proteins are missing from the 2-D gel patterns. Using the 2-D gel map and the information available in YDP, 2-D gel experiments were analyzed to characterize the yeast proteins associated with: (i) an environmental change (heat shock), (ii) a temperature-sensitive mutation (the prp2 mRNA splicing mutant), (iii) a mutation affecting post-translational modification (N-terminal acetylation), and (iv) a purified subcellular fraction (the ribosomal proteins). The methods used here should allow future extension of these studies to many more proteins of the yeast proteome.

Databases, Factual↗
PubMed1995

Enzymological differences of AChE and diazinon hepatic metabolism: correlation of in vitro data with the selective toxicity of diazinon to fish species.

The in vitro hepatic metabolism of diazinon, as well as the sensitivity of the brain acetylcholine esterase, to diazoxon inhibitory action have been studied in order to explain the different toxicity of diazinon to Oncorhynchus mykiss (rainbow trout), Poecilia reticulata (guppy), Brachydanio rerio (zebra fish) and Cyprinus carpio (carp). In spite of a very sensitive acetylcholine esterase the carp is very resistant to diazinon toxicity because of its very low rate of bioactivation and relatively high activity of detoxicating enzymes. The trout is very sensitive towards diazinon in spite of its low activity of bioactivation, because of its lack of detoxicating enzymes and a very sensitive acetylcholine esterase. Diazinon is very toxic for the guppy, because this fish combines a relatively sensitive acetylcholine esterase with a high rate of bioactivation. The zebra fish has the most insensitive acetylcholine esterase, associated with a limited activation rate, thus resulting a rather resistant species. The results obtained indicate that diazinon toxicity differences among the fish species studied can largely be explained in relation to metabolic balances in the liver and with the features of the target enzyme.

Acetylcholinesterase↗
PubMed1995

Patterns of gene action in plant development revealed by enhancer trap and gene trap transposable elements.

The crucifer Arabidopsis thaliana has been used widely as a model organism for the study of plant development. We describe here the development of an efficient insertional mutagenesis system in Arabidopsis that permits identification of genes by their patterns of expression during development. Transposable elements of the Ac/Ds system carrying the GUS reporter gene have been designed to act as enhancer traps or gene traps. A novel selection scheme maximizes recovery of unlinked transposition events. In this study 491 plants carrying independent transposon insertions were generated and screened for expression patterns. One-half of the enhancer trap insertions and one-quarter of the gene trap insertions displayed GUS expression in seedlings or flowers, including expression patterns specific to organs, tissues, cell types, or developmental stages. The patterns identify genes that act during organogenesis, pattern formation, or cell differentiation. Transposon insertion lines with specific GUS expression patterns provide valuable markers for studies of Arabidopsis development and identify new cell types or subtypes in plants. The diversity of gene expression patterns generated suggests that the identification and cloning of Arabidopsis genes expressed in any developmental process is feasible using this system.

Arabidopsis↗
PubMed1994

Inhibition of G1 cyclin activity by the Ras/cAMP pathway in yeast.

In the yeast Saccharomyces cerevisiae, commitment to cell division (Start) requires growth to a critical cell size. The G1 cyclins Cln1, Cln2 and Cln3 activate the Cdc28 protein kinase and are rate-limiting activators of Start. When glucose is added to cells growing in a poor carbon source, the critical cell size required for Start is reset from a small to a large size. In yeast, glucose acts through Ras proteins to stimulate adenylyl cyclase, activating the three cyclic AMP-dependent protein kinases Tpk1, Tpk2 and Tpk3 (refs 8, 9). We find that stimulation of the Ras/cAMP pathway represses expression of CLN1, CLN2 and co-regulated genes, inhibiting Start. This helps explain the increase in critical size when cells are shifted from poor to rich medium. This connection between the molecules controlling growth (Ras/cAMP) and those controlling division (cyclins) helps explain how division is co-ordinated with growth.

Cell Division↗
PubMed1994

Transvaginal sonography in the diagnosis of pelvic malignant recurrence: integration of sonography and needle-guided biopsy.

The aim of this study was to evaluate the efficiency of transvaginal sonography and sonography plus needle biopsy in detecting pelvic malignant recurrence. We scanned 24 patients already treated for gynecological malignancy, 21 of whom underwent needle biopsy under sonographic guidance. Thirteen patients were affected by cervical cancer, ten by ovarian cancer, and one by endometrial-ovarian carcinoma. Sonography detected 16 solid or cystic-solid masses (median size 52 mm, range 15-85 mm), one case of ascites, and one liquid mass (hematoma). All the patients in whom a suspicious mass was detected had recurrence. In the six patients in whom no mass was visible, two had recurrence. Needle biopsy was able to demonstrate recurrence in 17 patients (also in two false-negative scans). In one, even though sonography detected a mass, the histological sample was negative, but recurrence was later diagnosed by laparotomy.Accuracy, sensitivity and specificity of transvaginal sonography were respectively 91.6%, 89.4% and 100%. The positive predictive value was 100% and the negative predictive value was 71.4%. Transvaginal sonography was shown to be a useful means of detecting pelvic recurrence.

Journal Article↗
PubMed1994

Protein identifications for a Saccharomyces cerevisiae protein database.

The rapid progress in understanding the genes of the yeast Saccharomyces cerevisiae can be supplemented by two-dimensional (2-D) gel studies to understand global patterns of protein synthesis, protein modification, and protein degradation. The first step in building a protein database for yeast is to identify many of the spots on 2-D gels. We are using protein sequencing, overexpression of genes on high-copy number plasmids, and amino acid analysis to identify the proteins from 2-D gels of yeast. The amino acid analysis technique involves labeling yeast samples with different amino acids and using quantitative image analysis to determine the relative amino acid abundances. The observed amino acid abundances are then searched against the current database of 2600 known yeast protein sequences. At present about 90 proteins on our yeast maps have been identified, and the number is rising rapidly. With many known proteins on the map, it will soon be possible to use 2-D gel analysis to study regulatory pathways in normal and mutant yeast, with knowledge of many the protein products that respond to each genetic or environmental manipulation.

Amino Acid Sequence↗
PubMed1992

Operable breast cancer: a review of neoadjuvant chemotherapy.

Neoadjuvant chemotherapy in operable breast carcinoma (Ia-IIb) may influence the disease development reducing recurrence rate. A survey was conducted from 1975 to 1989 in an attempt to evaluate if pre- and peri-operative chemotherapy is able to improve the survival rate. However, available literature shows that only some Authors observed an increased disease free-survival rate among N- patients.

Breast Neoplasms↗
PubMed1991

Localization and management of occult breast lesions.

Mammography is an effective method for finding lesions of the breast which are occult at clinical examination. For occult lesions biopsy, including as little surrounding tissue as possible, it is necessary that they be located before surgery in order to improve the pathological process and the cosmetic outcome for the patients. Among the clinically occult lesions shown only by mammography, the frequency of breast cancers ranges from 10% to 47%. There are several different techniques for locating hidden lesions of the breast. We have employed the insertion of a single rigid needle into the breast, with X-ray confirmation of correct positioning. Forty-nine patients underwent this technique in our Institution and in all cases we were able to achieve a correct insertion of the needle at the X-ray check (the tip of the needle was less than 1 cm from the lesion). The target lesion was removed (as confirmed by X-ray of the surgical specimen) in all cases at the first attempt. In our study we found 11 invasive and 7 in situ tumours (36%). No complications delaying the surgical biopsy or the recovery of the patients were observed.

Adult↗
PubMed1990

[Occult mammary lesions: preoperative localization. Review of the literature].

The preoperative localisation of occult mammary lesions can be performed using fine needle biopsies, thus limiting esthetic damage in those patients in whom histological tests prove the lesion to be benign. Various methods have been proposed over the past 20 years. The purpose of this paper is to evaluate published data in order to determine which is the most appropriate method in terms of simplicity and efficacy.

Breast Diseases↗
PubMed1989

Complications of uterine cervix carcinoma treatments: the problem of a uniform classification.

Ninety-six articles published in English, French and Italian between 1938 and 1986 have been examined in order to analyze the classifications and reporting methods used by different researchers. Specialty and nationality of authors, classifications used, organs, systems and anatomic sites considered, weight given to the most frequently encountered complications are studied. Fifty-nine papers make no use of classification of complications of any kind, neither by onset time, nor by severity, but simply describe the observed events. The remaining 37 papers use a classification based on varying criteria. Thirty-four authors use a classification by severity according to different criteria; four authors classify complications according to the treatment required. In the remaining 30 papers a true scale is used. A total of 22 classifications emerges from these papers; in eight cases a previously published classification is used. The weight assigned by different authors to specific complications has been compared. The following main points emerge from the analysis: about two authors out of three simply describe the observed complications; 30 rely on a true scale of severity, but 22 different grading systems are used. Most classifications do not cover all possible complications, both surgical and radiotherapeutic, but concentrate on those complications which are typically generated by author's therapeutic approach. Only three take into account complications related to different treatment modalities. The observation period is not standardized: published data derive from follow-up times spanning from some months to many years. Authors mainly focus their interest on gastrointestinal and/or urinary complications; other organs and systems are rarely considered.(ABSTRACT TRUNCATED AT 250 WORDS)

Antineoplastic Agents↗
PubMed1989

Is the published literature a reliable guide for deciding between alternative treatments for patients with early cervical cancer?

The quality of the methodology and reporting of studies on the treatment of early cervical cancer published in English and French language over the period 1975-1985 were examined using an explicit, pre-defined protocol aimed at assessing their internal validity and generalizability. One hundred and fifty-two articles reporting results on over 40,000 patients treated with surgery, radiotherapy, or the combination of the two, were examined. The astonishing lack of formal comparative studies together with the poor quality of those actually carried out were the two major findings of our study. More than half of the reviewed papers (54%) were single series studies. Among the remaining 46% only a few formally compared the two treatments (i.e. surgery vs. radiotherapy), the remainder dealing with comparisons of specific surgical or radiotherapeutic techniques. With reference to study quality, the existence of a pre-specified research protocol could not be ascertained in most studies. A description of patients' characteristics and information on the source population were deficient in most papers reviewed; information on the two aspects was in fact satisfactorily reported in only 7% and 47% of the papers, respectively. Finally, the lack of standardization of follow-up methods (i.e. type and modalities) and of information on treatment compliance were two other severe methodological deficiencies. In view of this poor quality and of the intrinsic difficulty of drawing firm scientific conclusions from non-experimental investigations, the reliability of this literature remains highly dubious. Another possible caveat is that what is published is a biased sample of the overall evidence because of the well known tendency of authors to write about and editors to publish positive results more frequently than negative ones.

Clinical Trials as Topic↗