Ecological studies on the deep-water pelagic community of Korsfjorden (western Norway)

As part of a project aimed at assessing the available energy in a pelagic system and the efficiency of its transfer, monthly biomass estimates of the 23 main macroplanktonic and mesoplanktonic species have been made in Korsfjorden (Norway). Sampling was carried out over approximately 3 years (1971–1974) and results are presented as mg dry weight in a 690 m³ water column. The total annual stocks of the various species were not constant in the 3 years of sampling. Principal components analyses of the monthly stocks in each of the 3 years show striking differences in the correlation matrices from year to year. On the basis of known and supposed feeding habits, the species have been classified as herbivores, omnivores, or carnivores. The monthly biomass estimates of these groups show a consistent pattern from year to year. This, in contrast to the variable correlations between individual species, indicates that there can be considerable flexibility in the specific composition of a planktonic community without correspondingly marked effects on its trophic structure.     

Application of antimony microelectrodes to intracellular pH monitoring

Some novel studies of the properties of the antimony microelectrode used for intracellular pH measurements are described. First, it is shown that currents in the picoampere range, such as those encountered as leakage in some electrometers, induce important changes in pH sensitivity. The response time of the electrode has also been measured and indicates that the electrode exhibits a rapid time course which would be very useful for dynamic cytoplasmic pH investigations. An example of internal pH recording during cellular acidification in Xenopus laevis oocyte is also presented.     

Periodontal disease in the prehistoric Ipiutak and Tigara skeletal remains from Point Hope,Alaska

Two large groups of prehistoric Eskimo skeletons from Point Hope, Alaska, were evaluated for dental wear and several measures of periodontal disease. Occlusal attrition was found to increase steadily with increasing age. Crown height decreased proportionately. Assessing periodontal disease by inspecting apparent alveolar recession was judged ineffective due to possible supereruption. Infrabony pockets, the result of severe localized periodontal disease indicated that in Ipiutak people between the ages of 25 and 30, and Tigara people between 35 and 40, more dental sites were affected by periodontal disease than were not. This suggests a cultural, genetic, or dietary difference between the two groups. Male/female differences were slight in all parameters studied.     

Crystallization of beta-galactosidase from Escherichia coli.

Two crystal forms of beta-galactosidase have been obtained from Escherichia coli. One crystal form is hexagonal space group P6222 or enantiomorph, with cell dimensions a = b = 154 A, c = 750 A. The second form is monoclinic, space group P21, with cell dimensions a = 107.9 A, b = 207.5 A, c = 509.9 A, beta = 94.7 degrees. The monoclinic form seems better suited to detailed structural analysis. The crystals are radiation-sensitive, but by using synchrotron radiation in conjunction with a long (400 mm) crystal-to-film distance it was possible to resolve the individual reflections. On the basis of crystal density measurements, there are four tetramers each of molecular weight 465,000 per asymmetric unit. The Patterson function strongly suggests that two of the tetramers are related to the other two by translation. The data are consistent with the tetramers having 222 point symmetry, but this is not proven.     

beta-Furfuryl-beta-Glucoside: An Endogenous Activator of Higher Plant UDP-Glucose:(1-3)-beta-Glucan Synthase : Biological Activity, Distribution, and in Vitro Synthesis

In a recent paper (P Ohana, DP Delmer, JC Steffens, DE Matthews, R Mayer, M Benziman [1991] J Biol Chem 266: 13472-13475), we described the purification and structural characterization of β-furfuryl-β-glucoside (FG), an endogenous activator of plant UDP-glucose:(1→3)-β-glucan (callose) synthase. In the present report, we provide evidence that FG specifically stimulates callose synthase. The effects of FG on the kinetic properties of callose synthase were studied, and we ascertained that FG, or at least a very similar compound, is present in other plant systems. Chemically synthesized α-furfuryl-β-glucoside also stimulates callose synthase, exhibiting a slightly higher K_a of 80 micromolar, compared with 50 micromolar for FG. In addition, we have identified and partially characterized an enzyme that catalyzes the synthesis of FG using β-furfuryl alcohol and UDP-glucose as substrates. A model for the regulation of callose synthesis in vivo, involving changes in intracellular compartmentation of FG and Ca²⁺, is proposed.     

Differential accessibility of the tail domain of nuclear lamin A in interphase and mitotic cells

Human autoantibodies reactive against the tail domain exclusive to lamin A and absent from lamin C have been used for immunofluorescence studies on human fibroblast and epithelial cells. These autoantibodies were seen to react on mitotic cells where lamin A is present in a soluble depolymerized form and to react against lamin A in assembled interphase nuclear lamina after in situ extraction of chromatin. Taken together, these results support the suggestion that the tail domain of lamin A may be involved in the putative interaction of lamin A with chromatin.