Clinical aspects of ECL-cell abnormalities.

ECL cell hyperplasia results from hypergastrinemia, and in man this occurs due to achlorhydria in atrophic gastritis (pernicious anemia [PA]) and gastrinoma (Zollinger-Ellison syndrome [ZES]). Progression to neoplasia, i.e., ECL cell carcinoids (usually small, multicentric and non-functional), occurs in some five to 10 percent of patients with PA where they remain gastrin-dependent and reversible by normalization of serum gastrin by antrectomy. Even if untreated, the carcinoids are almost invariably benign and do not cause death. In ZES, ECL cell hyperplasia is progressive due to hypergastrinemia. However, carcinoids develop only in the MEN-I subtype but pose no additional threat of malignancy. A conservative approach is recommended for small multicentric carcinoids, and the tumors do not need removal. By contrast, single, large, non-gastrin-dependent carcinoids represent a different biological and clinical problem and are frequently malignant.     

The Pitcairn Islands, South Pacific Ocean: plate tectonic and climatic contexts

The remote Pitcairn Group in the South Pacific Ocean comprises a volcanic island (Pitcairn Island), two low coral atolls (Oeno, Ducie) and a raised coralline island (Henderson Island). The geological history of these islands, on anomalously thin oceanic lithosphere, is related to the development of two subparallel island chains (Oeno-Henderson-Ducie; Pitcairn) associated with intra-Pacific plate 'hotspot' activity; the surface manifestation of this activity has been partly determined by structural lineations in the plate inherited from past plate history. The climate of the Pitcairn Islands is determined by the position of the subtropical high pressure system and the South Pacific Convergence Zone. Variations in the strength of this atmospheric circulation system, measured by changes in the Southern Oscillation index of pressure difference, provide a partial explanation of the long-term variability of mean annual rainfall at Pitcairn Island. Knowledge of past climates in the Pitcairn Group remains speculative. Maps of the Pitcairn Islands and a report of climate at Henderson Island (2/91-1/92) are included in the paper.     

Analysis of water in Autonomous Biological Systems (ABS) samples.

Several soluble components, peptidase and amino acids, and carbon isotopic ratio in the water retrieved from flight experiments of Autonomous Biological Systems (ABS) as well as ground control samples are analyzed to interpret the condition, dynamics, material balance of the ABS ecosystems. Organic carbons in flight samples were found to be more abundant compared with the control ones, which suggested the uniform ecosystems in low gravity might easily dissolve more soluble components. The Mir-1997 flight sample showed higher C/N ratio probably because of the dissolution of carbon-rich plant materials.     

The light organ symbiont Vibrio fischeri possesses two distinct secreted ADP-ribosyltransferases.

We have previously described the purification, cloning, and initial characterization of a secreted ADP-ribosyltransferase, halovibrin (gene designation hvn), from the luminescent light organ symbiont Vibrio fischeri. This report describes a strategy for overexpression of halovibrin, the production and refinement of antihalo-vibrin antisera, and the molecular biological construction of a V. fischeri halovibrin null strain. Biochemical analysis of this mutant revealed that V. fischeri hvn null still possessed ADP-ribosyltransferase activity and that this activity is immunologically, genetically, and structurally distinct from the previously described enzyme. This unusual finding, of two ADP-ribosyltransferase enzymes produced by a microorganism, is complemented by the details of the purification to apparent homogeneity and in vitro regulation of this new protein, halovibrin-beta.     

Experimental evidence of environmental effects on age-specific reproductive success: the importance of resource quality.

Age-specific access to high-quality resources (e.g. territory or nest site) might be an important determinant for improved reproductive performance with increasing age. I experimentally investigated the effects of territory quality versus other age-related improvements in breeding competence (e.g. foraging skills, breeding experience and local knowledge) on age-specific reproductive success. Territory quality (i.e. territory field layer height) was manipulated in year 2 of northern wheatears (Oenanthe oenanthe) that were breeding in the same territory in two consecutive years. Changing territory quality by changing field layer height had a strong effect on within-individual change in the reproductive success of wheatears. This effect was mainly due to a corresponding change in nest predation risk. When territory quality was kept constant (i.e. no between-year change in territory field layer height), within-individual reproductive success did not change between subsequent years. Thus, age-related improvements in foraging skills, breeding experience and local familiarity had no significant effect on within-individual changes in reproductive success. Increased reproductive success with increased age in northern wheatears is therefore mainly explained by an improved access to high-quality territories with increasing age. I conclude that age-dependent access to high-quality breeding resources might be a widespread phenomenon in nature.     

Responses of Mentha suspension-cultured cells to 2,4-dichlorophenoxyacetic acid and accumulation of esterified phenolic acids in their cell walls.

Two distinct types of cell growth of suspension-cultured Mentha were formed when the cells maintained in the medium containing 1000 micrograms l-1 2,4-D were subcultured into different 2,4-D concentrations. Few cell elongation of Mentha (average cell length: 34-40 microns) was observed after division in the medium containing 1-200 micrograms l-1 2,4-D; and significant cell elongation (average cell length: 95-130 microns) was observed after cell division in the medium containing 500-2000 micrograms l-1 2,4-D. A close correlation between culture medium and water content in the cells indicated that 2,4-D promoted cell elongation by water uptake. Amounts of phenolic acid in cell walls were much higher in unelongated cell walls than in elongated ones during the cultivation, and there was a close correlation between the amounts and the level of PAL activity in elongated and unelongated cells. However, there was no significant difference in cell wall components and its neutral sugar composition between elongated and unelongated cells.     

Increased demand for NAD+ relative to ATP drives aerobic glycolysis

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