Induction of competence and progression signals in human T lymphocytes by phorbol esters and calcium ionophores

We have investigated the induction of competence (IL-2 responsiveness) and progression in human T lymphocyte proliferation triggered by phorbol ester and calcium ionophore. The degree of proliferation induced with the phorbol ester, phorbol 12,13-dibutyrate (PDB) and the calcium ionophore ionomycin was dependent on the duration of exposure to these agents, with more than 6 h required for obtaining maximum proliferation. Following brief exposure to both agents for 30 min, which did not cause significant proliferation, T cells became competent to proliferate in response to exogenous interleukin 2 (IL-2). These competent T cells also progressed to DNA synthesis following incubation with PDB in the absence of ionomycin. Induction of competence to proliferate in response to either PDB or IL-2 was blocked by EGTA, suggesting that transmembrane Ca2+ flux was obligatory at this stage. Since other phorbol esters and synthetic diacylglycerols also stimulated DNA synthesis in competent cells, it is likely that progression was triggered by activation of protein kinase C. Following a brief exposure to PDB and ionomycin, subsequent incubation with PDB induced gene expression and secretion of IL-2 and augmented the expression of IL-2 receptors in the competent cells. Thus, we have demonstrated that Ca2+ mobilization is required for rendering T cells competent to express functional IL-2 receptors, to produce IL-2 in response to subsequent incubation with PDB, and that sustained activation of protein kinase C seems necessary for IL-2 production and subsequent progression of competent T cells to DNA synthesis.     

Foraging interactions between Wandering Albatrosses Diomedea exulans breeding on Marion Island and long-line fisheries in the southern Indian Ocean

Wandering Albatrosses Diomedea exulans are frequently killed when they attempt to scavenge baited hooks deployed by long-line fishing vessels. We studied the foraging ecology of Wandering Albatrosses breeding on Marion Island in order to assess the scale of interactions with known long-line fishing fleets. During incubation and late chick-rearing, birds foraged further away from the island, in warmer waters, and showed high spatial overlap with areas of intense tuna Thunnus spp. long-line fishing. During early chick-rearing, birds made shorter foraging trips and showed higher spatial overlap with the local Patagonian Toothfish Dissostichus eleginoides long-line fishery. Tracks of birds returning with offal from the Toothfish fishery showed a strong association with positions at which Toothfish long-lines were set and most diet samples taken during this stage contained fishery-related items. Independent of these seasonal differences, females foraged further from the islands and in warmer waters than males. Consequently, female distribution overlapped more with tuna long-line fisheries, whereas males interacted more with the Toothfish long-line fishery. These factors could lead to differences in the survival probabilities of males and females. Non-breeding birds foraged in warmer waters and showed the highest spatial overlap with tuna long-line fishing areas. The foraging distribution of Marion Island birds showed most spatial overlap with birds from the neighbouring Crozet Islands during the late chick-rearing and non-breeding periods. These areas of foraging overlap also coincided with areas of intense tuna long-line fishing south of Africa. As the population trends of Wandering Albatrosses at these two localities are very similar, it is possible that incidental mortality during the periods when these two populations show the highest spatial overlap could be driving these trends.     

Patterns of approximal wear in cheek teeth of a Romano-British population

The approximal surfaces of premolars and molars of 376 adult British-Romano skulls were examined for wear facets. The type of wear was designated as convex, concave, sigmoid, or flat, and the degree was categorised on a three-point scale. Concave wear facets were more frequently seen in the older age groups, but the type of wear was similar on right and left sides. Taking all teeth together or as individual tooth types, concave wear was significantly more likely on mesial rather than distal surfaces. The degree of wear was age related and similar on right and left sides in both males and females. It is suggested that the distribution of concave facets may be related to movements between adjacent teeth.     

Three-dimensional structure of potato carboxypeptidase inhibitor in solution. A study using nuclear magnetic resonance, distance geometry, and restrained molecular dynamics

The solution conformation of potato carboxypeptidase inhibitor (CPI) has been investigated by 1H NMR spectroscopy. The spectrum is assigned in a sequential manner by using two-dimensional NMR techniques to identify through-bond and through-space (less than 5 A) connectivities. A set of 309 approximate interproton distance restraints is derived from the two-dimensional nuclear Overhauser enhancement spectra and used as the basis of a three-dimensional structure determination by a combination of metric matrix distance geometry and restrained molecular dynamics calculations. A total of 11 converged distance geometry structures were computed and refined by using restrained molecular dynamics. The average atomic root mean square (rms) difference between the final 11 structures and the mean structure obtained by averaging their coordinates is 1.4 +/- 0.3 A for residues 2-39 and 0.9 +/- 0.2 A for residues 5-37. The corresponding values for all atoms are 1.9 +/- 0.3 and 1.4 +/- 0.2 A, respectively. The larger values for residues 2-38 relative to those for residues 5-37 arise from the fact that the positions of the N- (residues 1-4) and C- (residues 38-39) terminal tails are rather poorly determined, whereas those of the core of the protein (residues 5-37) are well determined by the experimental interproton distance data. The computed structures are very close to the X-ray structure of CPI in its complex with carboxypeptidase, and the backbone atomic rms difference between the mean of the computed structures and the X-ray structure is only 1.2 A. Nevertheless, there are some real differences present which are evidenced by significant deviations between the experimental upper interproton distance limits and the corresponding interproton distances derived from the X-ray structure. These principally occur in two regions, residues 18-20 and residues 28-30, the latter comprising part of the region of secondary contacts between CPI and carboxypeptidase in the X-ray structure.