A silurian soft-bodied biota

A new Silurian (Llandoverian) biota from Wisconsin with a significant soft-bodied and lightly sclerotized component is dominated by arthropods and worms. The fauna includes the earliest well-preserved xiphosure, a possible marine uniramian, three new arthropods of uncertain affinity, and possibly the first Paleozoic leech. This may be only the second locality to yield a conodont animal. Lack of a normal shelly fauna suggests an unusual environment. The discovery adds significantly to the few such exceptionally preserved faunas known from Lower Paleozoic rocks.     

Trans-endocytosis of CD80 and CD86: a molecular basis for the cell-extrinsic function of CTLA-4

Cytotoxic T lymphocyte antigen 4 (CTLA-4) is an essential negative regulator of T cell immune responses whose mechanism of action is the subject of debate. CTLA-4 shares two ligands (CD80 and CD86) with a stimulatory receptor, CD28. Here, we show that CTLA-4 can capture its ligands from opposing cells by a process of trans-endocytosis. After removal, these costimulatory ligands are degraded inside CTLA-4-expressing cells, resulting in impaired costimulation via CD28. Acquisition of CD86 from antigen-presenting cells is stimulated by T cell receptor engagement and observed in vitro and in vivo. These data reveal a mechanism of immune regulation in which CTLA-4 acts as an effector molecule to inhibit CD28 costimulation by the cell-extrinsic depletion of ligands, accounting for many of the known features of the CD28-CTLA-4 system.     

The galilean satellites and jupiter: voyager 2 imaging science results

Voyager 2, during its encounter with the Jupiter system, provided images that both complement and supplement in important ways the Voyager 1 images. While many changes have been observed in Jupiter's visual appearance, few, yet significant, changes have been detected in the principal atmospheric currents. Jupiter's ring system is strongly forward scattering at visual wavelengths and consists of a narrow annulus of highest particle density, within which is a broader region in which the density is lower. On Io, changes are observed in eruptive activity, plume structure, and surface albedo patterns. Europa's surface retains little or no record of intense meteorite bombardment, but does reveal a complex and, as yet, little-understood system of overlapping bright and dark linear features. Ganymede is found to have at least one unit of heavily cratered terrain on a surface that otherwise suggests widespread tectonism. Except for two large ringed basins, Callisto's entire surface is heavily cratered.     

Net selectivity studies in the Northern Ireland Nephrops fishery

The effect on catch composition of a large mesh lifter net fitted to a trawl cod-end was investigated in the Northern Ireland Nephrops fishery in the north west Irish Sea (ICES area Vila). Two experiments were conducted using chartered commercial fishing vessels. In the first experiment, parallel hauls showed there to be no significant difference in the Ncphrops size distribution caught by nets with and without a lifter net. The result of the second experiment, in which the cod-end was fitted with a small mesh cover to retain escaping Nephrops, did not suggest that the cod-end meshes were blinded by the lifter. Field data are contrasted with those from theoretical studies of mesh obstruction.     

The distribution of aldicarb and its metabolites between Lumbricus terrestris,water and soil

Aldicarb is taken up by earthworms from aqueous solution to give concentrations in the worms comparable to that in the external aqueous solutions. Uptake from waterlogged soils is similar, but much less aldicarb is taken up from drier soils. Aldicarb sulphoxide [2-methyl-2-(methylsulphinylpropionaldehyde O-methylcar-bamoyloxime], aldoxycarb and oxamyl are poorly taken up, giving concentrations in the worm of about 5% of the external aqueous concentration. In worms, aldicarb is rapidly converted to the sulphoxide which has a half-life in worms of 19 h at 15°C, and 50 h at 5°C.