DETERMINATION OF GUSTATORY SUCROSE THRESHOLD IN WATER BY USE OF A LINEAR SUCROSE GRADIENT

A novel experimental method was developed which allows the determination of the threshold concentration of sucrose by use of a linear sucrose gradient in water. With this method a continuous tasting of the test-liquid is possible. A panel of 15 persons experienced in taste-testing was used. Three gradients of different steepness were applied: 0 to 1.5% (w/w) sucrose in 2 min (I), 3 min (II) and 4 min (III). The results of the new method were compared with those of the standard method (DIN). With gradients I and II we found values which were significantly higher than those of the standard method (I: 0.49% (w/w); II: 0.46% (w/w); DIN: 0.31% (w/w)), whereas with gradient III the same threshold value was found as with the DIN-Method (III: 0.32% (w/w)).     

Growth hormone and prolactin secretion in Huntington's disease.

Growth hormone (GH) and prolactin (PRL) secretion was studied in twelve patients with Huntington's Disease, eight unaffected relatives, and twenty normal subjects in response to provocative and suppressive tests. Prolactin responses to TRH, chlorpromazine, L-DOPA, and apormorphine were similar in all groups with the exception of a slightly blunted PRL response to THR in the unaffected relatives. Although GH responses to L-DOPA were similar in all groups, patients with Hungtinton's Disease had nearly absent GH responses to apomorphine (mean peak GH = 1.4±0.4 (SE) ng/m1) compared to normal control subjects (mean peak GH = 28.9±8.6 ng/m1). These results, which are similar to some previously reported findings in drug-induced tardive dyskinesia, suggest an abnormality in dopamine-mediated GH secretion in Huntington's Disease.     

Effect of neurotensin on pancreatic function in man

The effect of neurotensin on submaximally-stimulated hepatobiliary and pancreatic secretion was studied in 6 healthy subjects. An intravenous infusion of neurotensin 1.4 ± 0.3 pmol/kg/min, designed to reproduce plasma neurotensin immunoreactivity levels within the physiological range, produced a significant increase in pancreatic bicarbonate output. Plasma concentrations of pancreatic polypeptide rose by 83 ± 16 pmol/l and were associated with a small reduction in trypsin, but no significant change in bilirubin outputs.     

Delimitation of the maritime boundary in the gulf of Maine area

The compulsory dispute settlement regime included in the 1982 Law of the Sea Convention is recognized as one of the most comprehensive in a modern international convention. Yet, in the recent application of this regime, the question has arisen as to whether the procedural prerequisites associated with the LOS Convention's compulsory dispute settlement mechanism are so arduous as to avoid binding and compulsory jurisdiction in most instances. This article addresses that question by examining, in particular, the reasoning of the Southern Bluefin Tuna arbitration tribunal, which found Article 281 of Section 1 of the LOS Convention to bar jurisdiction to the compulsory dispute settlement mechanism prescribed by the Convention, and offers suggestions as to how states might distinguish or overcome the barriers imposed by the Southern Bluefin Tuna tribunal in future cases.     

Quantitative proteomic analysis of Myc oncoprotein function

This study applies a new quantitative proteomics technology to the analysis of the function of the Myc oncoprotein in mammalian cells. Employing isotope-coded affinity tag (ICAT) reagent labeling and tandem mass spectrometry, the global pattern of protein expression in rat myc-null cells was compared with that of myc-plus cells (myc-null cells in which myc has been introduced) to generate a differential protein expression catalog. Expression differences among many functionally related proteins were identified, including reduction of proteases, induction of protein synthesis pathways and upregulation of anabolic enzymes in myc-plus cells, which are predicted to lead to increased cell mass (cell growth). In addition, reduction in the levels of adhesion molecules, actin network proteins and Rho pathway proteins were observed in myc-plus cells, leading to reduced focal adhesions and actin stress fibers as well as altered morphology. These effects are dependent on the highly conserved Myc Box II region. Our results reveal a novel cytoskeletal function for Myc and indicate the feasibility of quantitative whole-proteome analysis in mammalian cells.     

Proteomics without polyacrylamide: qualitative and quantitative uses of tandem mass spectrometry in proteome analysis

Proteomics can be thought of as an attempt to understand the information encoded in genomic sequences from the perspective of proteins; i.e. the structure, function and regulation of biological processes at the protein level. In practice it stands in stark contrast to the hypothesis-driven serial approach practiced in the last century that was so successful for protein chemists and is built on the basic understanding of protein physicochemical properties developed during that era. Proteomics attempts to study biological processes comprehensively or globally by systematic parallel analysis of proteins expressed in a cell. While there are many analytical techniques in use and under development in proteomics, mass spectrometry is currently one of the field's most important discovery-based tools. This article will review some of the current approaches for qualitative and quantitative uses of tandem mass spectrometry in the field of proteomics specifically avoiding a discussion of the use of gel electrophoresis prior to mass spectrometry. Electronic Publication     

Shotgun proteomic analysis of a chromatophore-enriched preparation from the purple phototrophic bacterium Rhodopseudomonas palustris

A proteomics approach was evaluated for analysis of photosyntheis-related proteins that are characteristic of chromatophores, particles derived from purple phototrophic bacterial intracytoplasmic membranes. Proteins of purified chromatophores from Rhodopseudomonas palustris were solubilized and digested with trypsin, to create a collection of peptides that were fractionated by liquid chromatography. Peptide sequences were determined and assigned to specific proteins by analysis of tandem mass spectra of peptides, and comparison to a library derived from the recently determined R. palustris genome sequence. A total of 300 proteins were detected with a probability value >/=0.9, and the number of proteins detected increased to 345 when the minimum probability value was reduced to 0.5. Membrane-integral proteins of the reaction center, cytochrome b/c (1), light-harvesting and ATPase complexes were used as controls to assess how well this approach performs with hydrophobic proteins. New genes were identified, and tentatively designated as encoding photosynthesis-related proteins. We conclude that this approach is a powerful method to evaluate the possible existence of new photosynthesis-related proteins (and genes), although alternative methods are needed to evaluate the exact functions of newly discovered genes.     

Intersection of the Kap123p-mediated nuclear import and ribosome export pathways

Kap123p is a yeast beta-karyopherin that imports ribosomal proteins into the nucleus prior to their assembly into preribosomal particles. Surprisingly, Kap123p is not essential for growth, under normal conditions. To further explore the role of Kap123p in nucleocytoplasmic transport and ribosome biogenesis, we performed a synthetic fitness screen designed to identify genes that interact with KAP123. Through this analysis we have identified three other karyopherins, Pse1p/Kap121p, Sxm1p/Kap108p, and Nmd5p/Kap119p. We propose that, in the absence of Kap123p, these karyopherins are able to supplant Kap123p's role in import. In addition to the karyopherins, we identified Rai1p, a protein previously implicated in rRNA processing. Rai1p is also not essential, but deletion of the RAI1 gene is deleterious to cell growth and causes defects in rRNA processing, which leads to an imbalance of the 60S/40S ratio and the accumulation of halfmers, 40S subunits assembled on polysomes that are unable to form functional ribosomes. Rai1p localizes predominantly to the nucleus, where it physically interacts with Rat1p and pre-60S ribosomal subunits. Analysis of the rai1/kap123 double mutant strain suggests that the observed genetic interaction results from an inability to efficiently export pre-60S subunits from the nucleus, which arises from a combination of compromised Kap123p-mediated nuclear import of the essential 60S ribosomal subunit export factor, Nmd3p, and a DeltaRAI1-induced decrease in the overall biogenesis efficiency.     

Metabolic capabilities and systems fluctuations in Haloarcula marismortui revealed by integrative genomics and proteomics analyses

The 1310 Haloarcula marismortui proteins identified from mid-log and late-log phase soluble and membrane proteomes were analyzed in metabolic and cellular process networks to predict the available systems and systems fluctuations upon environmental stresses. When the connected metabolic reactions with identified proteins were examined, the availability of a number of metabolic pathways and a highly connected amino acid metabolic network were revealed. Quantitative spectral count analyses suggested 300 or more proteins might have expression changes in late-log phase. Among these, integrative network analyses indicated approximately 106 were metabolic proteins that might have growth-phase dependent changes. Interestingly, a large proportion of proteins in affected biomodules had the same trend of changes in spectral counts. Disregard the magnitude of changes, we had successfully predicted and validated the expression changes of nine genes including the rimK, gltCP, rrnAC0132, and argC in lysine biosynthesis pathway which were downregulated in late-log phase. This study had not only revealed the expressed proteins but also the availability of biological systems in two growth phases, systems level changes in response to the stresses in late-log phase, cellular locations of identified proteins, and the likely regulated genes to facilitate further analyses in the postgenomic era.