Regulation of leukocyte migration by activation of the leukocyte adhesion molecule-1 (LAM-1) selectin.

A central feature of host defence is the ability of leukocytes to enter tissues in response to immune or inflammatory stimuli. The leukocyte adhesion molecule-1 (LAM-1) regulates the migration of human leukocytes by mediating the binding both of lymphocytes to high endothelial venules of peripheral lymph nodes and of neutrophils to endothelium at inflammatory sites. As lymphocytes and neutrophils express the same LAM-1 protein, it is not clear how lineage-specific differences in leukocyte migration are controlled. We now report that the affinity of LAM-1 for a carbohydrate-based ligand, PPME, is dramatically increased following lymphocyte and neutrophil activation by lineage-specific stimuli. In addition, activation of lymphocytes by physiological stimuli enhanced LAM-1-dependent binding to high endothelial venules. Thus, transient changes in LAM-1 affinity after leukocyte stimulation probably directly influence leukocyte migration.     

Increased CO2 uncouples growth from isoprene emission in an agriforest ecosystem

The emission of isoprene from the leaves of forest trees is a fundamental component of biosphere-atmosphere interactions, controlling many aspects of photochemistry in the lower atmosphere. As almost all commercial agriforest species emit high levels of isoprene, proliferation of agriforest plantations has significant potential to increase regional ozone pollution and enhance the lifetime of methane, an important determinant of global climate. Here we show that growth of an intact Populus deltoides plantation under increased CO2 (800 micromol x mol(-1) and 1,200 micromol x mol(-1)) reduced ecosystem isoprene production by 21% and 41%, while above-ground biomass accumulation was enhanced by 60% and 82%, respectively. Exposure to increased CO2 significantly reduced the cellular content of dimethylallyl diphosphate, the substrate for isoprene synthesis, in both leaves and leaf protoplasts. We identify intracellular metabolic competition for phosphoenolpyruvate as a possible control point in explaining the suppression of isoprene emission under increased CO2. Our results highlight the potential for uncoupling isoprene emission from biomass accumulation in an agriforest species, and show that negative air-quality effects of proliferating agriforests may be offset by increases in CO2.     

Single zircon LAM－ICPMS U－Pb dating of Guidong complex （SE China） and its petrogenetic significance

Because of the strong effects of the Caledonian and Indosinian orogenies and Yanshanian magmatism since early Paleozoic time, different types of granites and ore deposits occur widely in the Nanling region of SE China[1]. The Guidong complex is situated at the border between the South Jiangxi—North Guangdong post-Caledonian orogenic belt and the Hercynian-Indosinian belt, which is constrained by an E-W regional deep fault (Guidong-Da- dongshan deep fault) and therefore is elongated nea…     

Cooperation and conflict in quorum-sensing bacterial populations

It has been suggested that bacterial cells communicate by releasing and sensing small diffusible signal molecules in a process commonly known as quorum sensing (QS). It is generally assumed that QS is used to coordinate cooperative behaviours at the population level. However, evolutionary theory predicts that individuals who communicate and cooperate can be exploited. Here we examine the social evolution of QS experimentally in the opportunistic pathogen Pseudomonas aeruginosa, and show that although QS can provide a benefit at the group level, exploitative individuals can avoid the cost of producing the QS signal or of performing the cooperative behaviour that is coordinated by QS, and can therefore spread. We also show that a solution to the problem of exploitation is kin selection, if interacting bacterial cells tend to be close relatives. These results show that the problem of exploitation, which has been the focus of considerable attention in animal communication, also arises in bacteria.     

Zircon U-Pb dating and Lu-Hf isotope study of intermediate-mafic sub-volcanic and intrusive rocks in the Lishui Basin in the middle and lower reaches of Yangtze River

Eight Mesozoic sub-volcanic and intrusive rocks in the Lishui Basin have been selected for zircon U-Pb dating and Lu-Hf isotopic analysis. The Laohutou, Datongshan,Daweizhuang, Yeshanao, Yanwaqiao, Xibeishan, Changshantou and Jianshan porphyrites yield concordant early Cretaceous ages of 130.5 ± 1.6 Ma, 136.0 ± 3.4 Ma, 132.7 ±2.7 Ma, 127.0 ± 1.9 Ma, 129.4 ± 1.7 Ma, 133.2 ± 2.1 Ma,131.1 ± 2.3 Ma and 127.4 ± 1.8 Ma, respectively. Zircon eHf(t) values for these rocks range from-3.54 to-9.11, mostly between-3.54 and-5.93, suggesting sources similar to those for coeval igneous rocks in other volcanic basins along the middle and lower reaches of Yangtze River. Considering the geochemical characteristics of coeval magmatic rocks in the middle and lower reaches of Yangtze River and its adjacent areas, this paper proposes a model of slab rollback to explain the Mesozoic magmatism in the east-central part of China continent. In the middle-late Jurassic to early Cretaceous(170–135 Ma), the Pacific plate started to subduct beneath the Eurasian continent, producing a compressive tectonic setting,and magmatism progressed from coast to the inland. The magmas of this period were derived mostly from partial melting of ancient crust. After *135 Ma, the subduction weakened, and the rollback of the subducted Pacific plate produced an extensional environment. This led to the formation of volcanic basins, the partial melting of enriched mantle sources and less ancient crust, and the intrusion of voluminous intermediate-mafic igneous rocks.     

Quinine dimorphism among ‘non-tasters’ of 6-n-propylthiouracil

Zusammenfassung Geschmacksblinde gegenüber 6-n-Propylthiouracil zerfallen in zwei Gruppen (Dimorphismus): eine mit niedrigen und eine mit hohen Geschmacksschwellenwerten gegenüber Chinin. Jene der ersten Gruppe haben niedrige Schwellenwerte auch gegenüber den andere Geschmacksqualitäten — sauer, salzig und süss — und gehören zur -Geschmacksgruppe. Vertreter der zweiten Gruppe, das heisst 6-n-Propylthiouracil-Geschmacksblinde mit hohen Geschmacksschwellenwerten gegenüberChinin gehören zu der -Geschmacksgruppe. Patienten mit paroxysmal vaskulärem Kopfschmerz (Migräne mit familiärer Komponente), jedoch ohne elektronencephalographische Anomalie, gehören ausschliesslich zu der -Geschmacksgruppe. Die Eltern von mongoloiden Kindern weisen hohe Geschmacksschwellenwerte gegenüber Chinin auf, wobei die Väter zur -Geschmacksgruppe gehören.

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MeinerAlma Mater, der Universität Basel, zu ihrem 500jährigen Jubiläum in Dankbarkeit gewidmet.

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Acknowledgements. This work has been supported by the State of Ohio, Department of Mental Hygiene and the U.S. Public Health Service, National Institutes of Health, Division of Mental Health, Grant No. M-2731. The active interest and helpful suggestions of Dr.B. Pasamanick is thankfully acknowledged. Our very special and sincere thanks go to Mr.S. England for his most valuable assistance, advice, and skillful help during many phases of this study.