Heteromorphe ammoniten aus dem unter-callovien („macrocephalen-schichten“) vom westrand der nördlichen frankenalb (s-deutschland)

Heteromorph Ammonites of the generaParapatoceras Spath,Paracuariceras Schindewolf undAcuariceras Spath from the Lower Callovian (“Macrocephalen-Schichten” of the Northern Franconian Alb are described. The species of the genusParapatoceras Spath are dominant. New finds of the generaParacuariceras Schindewolf andAcuariceras Spath show that their first occurence is in the Lower Callovian. The optimal biotope of the heteromorphs with vagile benthonic mode of life was probably, similar to the Swabian Dogger, in stillwater areas.     

Target cell lysis and IL-2 secretion by gamma/delta T lymphocytes after activation with bacteria

Peripheral blood T lymphocytes from healthy donors were stimulated with Mycobacterium tuberculosis in vitro and afterward analyzed phenotypically. Marked expansion of the gamma/delta T cell population (3- to 21-fold) was observed in 15/21 donors 7 to 10 days after stimulation. In addition to M. tuberculosis, Mycobacterium leprae (six of eight) as well as the gram-positive bacteria, Staphylococcus aureus (two of six), group A streptococci (seven of nine), and Listeria monocytogenes (four of eight) augmented gamma/delta TCR expression in peripheral blood T cells of many donors. gamma/delta T lymphocytes expressed IL-2R and secreted IL-2 upon restimulation with M. tuberculosis. Stimulation with M. tuberculosis evoked specific cytolytic activities in gamma/delta T lymphocytes because: gamma/delta T cells lysed M. tuberculosis pulsed but not unpulsed targets; high concentrations of TCR delta 1 mAb facilitated killing of unpulsed target cells; and low doses of anti-TCR delta 1 mAb blocked killing of pulsed targets. Furthermore, gamma/delta T cells from four donors, after activation with M. tuberculosis or with group A streptococci, respectively, only lysed targets pulsed with the homologous agents, whereas in other donors some cross-reactivity was observed. We conclude that, upon contact with mycobacteria and perhaps other microorganisms, gamma/delta T cells are activated which contribute to immunity against infection via IL-2 secretion and specific target cell lysis.     

Prey size spectra and prey availability of larval and small juvenile cod

The aim of the present study is to describe the prey preference characteristics of cod larvae and assess preference variability in relation to species and size composition of copepod prey. A further aim is to examine the hypothesis that dietary prey size spectra remain the same during the larval stage when viewed on a relative predator/prey size scale. The study is based on stomach analysis of larval/juvenile cod in the size range 10–35 mm from nursery grounds in the North Sea. Stomach contents (species, size) were compared to environmental composition and preference indices were calculated. Prey size spectra had the expected relationship to larval cod size, and preference for given copepod species could be ascribed to their relative size. Additional species-specific preferences were evident, for example the larger Pseudocalanus and the larger Calanus spp. were highly preferred. Available prey biomass was highest in the areas of a hydrographic front, where larvae have been shown to concentrate. Changes in prey availability with larval growth depend strongly on specific prey biomass spectra at a given location. Both increasing and decreasing prey availability at increasing larval size were indicated, dependent on location. The findings illustrate the usefulness of coupling dietary prey size spectra and biomass spectra of available prey sizes during studies of ichthyoplankton feeding ecology.