A NATURALLY OCCURRING DEVELOPMENTAL SYNERGISM BETWEEN THE CELLULAR SLIME MOLD,DICTYOSTELIUM MUCOROIDES AND THE FUNGUS,MUCOR HIEMALIS

We here report the second record of a developmentally aberrant strain of a cellular slime mold from natural populations and demonstrate that this Dictyostelium mucoroides variant is capable of undergoing normal morphogenesis in the presence of the phycomycete fungus, Mucor hiemalis. The synergism is induced by an extracellular product(s) which is diffusable through thin agar membranes and is released by the fungus. The presence of the fungus not only induces stalk formation in this stalkless variant, but also increases the rate of sorocarp formation in 3 of 5 additional species of cellular slime molds assayed.     

The Legal Regulation of Floats and Gliders—In Quest of a New Regime?

This article analyzes the legal status of unmanned instruments (particularly, floats and gliders) for observation purposes in the ocean environment. These new kinds of instruments are being deployed by the thousands into the oceans, not the least as part of the Argo Project of the International Oceanographic Commission. Their uncontrolled drifting has raised legal questions, especially when such instruments enter waters subject to the jurisdiction of foreign states. The authors argue that the current international legal framework is insufficient to address the pertinent issues, and that a new legal regime is needed.     

Losing the last feather: feather loss as an antipredator adaptation in birds

Birds often lose feathers during predation attempts, and thisability has evolved as a means of escape. Because predatorsare more likely to grab feathers on the rump and the back thanon the ventral side of an escaping bird, we predicted that theformer feathers would have evolved to be relatively looselyattached as an antipredator strategy in species that frequentlydie from predation. We estimated the force required to removefeathers from the rump, back, and breast by pulling featherswith a spring balance from a range of European bird speciesin an attempt to investigate ecological factors associated withease of feather loss during predation attempts. The force requiredto loosen a feather from the rump was less than that requiredto loosen a feather from back, which in turn was less than thatrequired to loosen a feather from the breast. The relative forceneeded to loosen rump feathers compared with feathers from theback and the breast was smaller for prey species preferred bythe most common predator of small passerine birds, the sparrowhawkAccipiter nisus. Likewise, the relative force was also smallerin species with a high frequency of complete tail loss amongfree-living birds, which we used as an index of the frequencyof failed predation attempts. The relative force required toremove feathers from the rump was smaller in species with ahigh frequency of fear screams, another measure of the relativeimportance of predation as a cause of death. Feather loss requiredparticularly little force among solitarily breeding bird speciesthat suffer the highest degree of predation. Antipredator defensein terms of force required to remove feathers from the rumpwas larger in species with a strong antiparasite defense interms of T-cell–mediated immune response. These findingsare consistent with the hypothesis that different defenses areantagonistic and that they are traded off against each other.     

Trace elements in rock salt and their bioavailability estimated from solubility in acid

In this study, 18 partly commercially available samples of rock salt from Austria, Germany, Pakistan, Poland, Switzerland, and Ukraine were investigated with respect to their content of trace elements using instrumental neutron activation analysis. Elements detected were Al, Ba, Br, Ca, Ce, Cl, Co, Cr, Cs, Eu, Fe, Hf, La, Mn, Na, Rb, Sb, Sc, Sm, Sr, Ta, Tb, Th, and Zn, some of them only in individual cases. An estimation of the bioavailability of these trace elements was performed by dissolving an equivalent of the sodium chloride samples in diluted hydrochloric acid (simulating stomach acid), filtering off the insoluble components, and analyzing the evaporated filtrate. It could be shown that in most cases bioactive trace elements like Fe can be found in rock salt in the form of almost insoluble compounds and are therefore not significantly bioavailable, whereas thorium, for example, was partly bioavailable in two cases. A significant contribution to the recommended daily intake of metal trace elements by using rock salt for nutrition can be excluded.     

Views,landmarks, and routes: how do desert ants negotiate an obstacle course?

The Australian desert ant Melophorus bagoti often follows stereotypical routes through a cluttered landscape containing both distant panoramic views and obstacles (plants) to navigate around. We created an artificial obstacle course for the ants between a feeder and their nest. Landmarks comprised natural objects in the landscape such as logs, branches, and tussocks. Many ants travelled stereotypical routes home through the obstacle course in training, threading repeatedly the same gaps in the landmarks. Manipulations altering the relations between the landmarks and the surrounding panorama, however, affected the routes in two major ways. Both interchanging the positions of landmarks (transpositions) and displacing the entire landmark set along with the starting position of the ants (translations) (1) reduced the stereotypicality of the route, and (2) increased turns and meanders during travel. The ants might have used the entire panorama in view-based travel, or the distal panorama might prime the identification and use of landmarks en route. Despite the large data set, both options (not mutually exclusive) remain viable.     

Bone Morphogenetic Protein 7 (BMP-7) Influences Tendon-Bone Integration In Vitro

IntroductionSuccessful graft ingrowth following reconstruction of the anterior cruciate ligament is governed by complex biological processes at the tendon-bone interface. The aim of this study was to investigate in an in vitro study the effects of bone morphogenetic protein 7 (BMP-7) on tendon-bone integration.ResultsIn both models, positive effects of BMP-7 on ALP enzyme activity were observed (p<0.001). Additionally, similar results were noted for LDH activity and lactate concentration. BMP-7 stimulation led to a significant increase in OCN expression. Whereas the effects of BMP-7 on tendon monoculture peaked during an early phase of the experiment (p<0.001), the cocultures showed a maximal increase during the later stages (p<0.001). The histological analysis showed a stimulating effect of BMP-7 on extracellular matrix formation. Organized ossification zones and calcium carbonate-like structures were only observed in the BMP-stimulated cell cultures.DiscussionThis study showed the positive effects of BMP-7 on the biological process of tendon-bone integration in vitro. Histological signs of improved mineralization were paralleled by increased rates of osteoblast-specific protein levels in primary bovine osteoblasts and fibroblasts.ConclusionOur findings indicated a role for BMP-7 as an adjuvant therapeutic agent in the treatment of ligamentous injuries, and they emphasized the importance of the transdifferentiation process of tendinous fibroblasts at the tendon-bone interface.