CO2 enrichment predisposes foliage of a eucalypt to freezing injury and reduces spring growth

Seedlings of Eucalyptus pauciflora, were grown in open-top chambers fumigated with ambient and elevated [CO₂], and were divided into two populations using 10% light transmittance screens. The aim was to separate the effects of timing of light interception, temperature and [CO₂] on plant growth. The orientation of the screens exposed plants to a similar total irradiance, but incident during either cold mornings (east-facing) or warm afternoons (west-facing). Following the first autumn freezing event elevated CO₂-grown plants had 10 times more necrotic leaf area than ambient CO₂ plants. West-facing plants had significantly greater (25% more) leaf damage and lower photochemical efficiency (F_v/F_m) in comparison with east-facing plants. Following a late spring freezing event east-facing elevated CO₂ plants suffered a greater sustained loss in F_v/F_m than west-facing elevated CO₂- and ambient CO₂-grown plants. Stomatal conductance was lower under elevated CO₂ than ambient CO₂ except during late spring, with the highest leaf temperatures occurring in west-facing plants under elevated CO₂. These higher leaf temperatures apparently interfered with cold acclimation thereby enhancing frost damage and reducing the ability to take advantage of optimal growing conditions under elevated CO₂.     

Mechanism of Coagulation in Gecarcinus lateralis

Agglutination of cells, degranulation, and loss of cellularmembranes compose the major form of coagulation in the hemolymphof Gecarcinus lateralis. It is only after agglutination of theformed elements of the hemolymph that fibrin-like strands appear.Sodium citrate, in a concentration of 10% or more to preventcoagulation, is always inadequate to prevent cell agglutination. Multiple studies by protein electrophoresis failed to revealany differences between plasma and serum, nor did they allowus to identify a soluble protein in plasma that did not appearin serum. Crab hemolymph changes in its capacity for clottingduring the molt cycle, with the most rapid clotting occurringin the premolt period. A new protein appears in the premoltperiod, but its relation to the whole clotting mechanism isunknown. In contradistinction to vertebrate systems, citrated hemolymphdoes not clot when calcium is added. There is no relationshipthat can be demonstrated between activating systems in vertebrateplasma and clotting in the crab. It would seem that, ratherthan the vertebrate coagulating system evolving from the crustaceantype of clotting system, the development of these clotting systemshas run in parallel. The crustacean cell, in addition, appearsto be more potent than vertebrate cells in clotting systems.The comparison of human lymph to crustacean hemolymph wouldindicate that, for a given amount of cells, crustacean hemolymphclots 2 to 20 times faster than human lymph. On the other hand,agglutination of cells is a fundamental initiating step in coagulationof both human blood and crustacean hemolymph.     

Fate of Maturation Protein during Infection by Coliphage MS2

RNA coliphages contain two species of protein: coat protein, the major structural component; and maturation protein, which is probably present in only one copy per virion^1–3. The precise function of maturation protein is uncertain, but it is required for phage adsorption to F-pili of the E. coli host⁴ and for reconstitution of infectious phage⁵. In infected cells, newly synthesized maturation protein is found associated with viral RNA⁶, suggesting that an RNA-maturation protein complex may be present in virus particles.     

Evolution of Delphacidae (Hemiptera: Fulgoroidea): combined‐evidence phylogenetics reveals importance of grass host shifts

The planthopper family Delphacidae is a speciose lineage of phloem‐feeding insects, with many species considered as pests of economic significance on essential world food commodities (including rice, maize, wheat, barley and sugar cane). Despite their economic importance, evolutionary relationships among delphacids, particularly those within the speciose tribe Delphacini, are largely unknown. Presented here are the results of a phylogenetic investigation of Delphacidae based on DNA nucleotide sequence data from four genetic loci (18S rDNA, 28S rDNA, wingless and cytochrome oxidase I) and 132 coded morphological characters. The resulting topologies are used to test the higher classification of Delphacidae and to examine evolutionary patterns in host–plant associations. Our results generally support the higher classifications of Delphacidae proposed by Asche, Emeljanov and Hamilton, and suggest that the rapid diversification of the Delphacini was associated with host shifts to, and within, Poaceae, and specifically from C3 to C4 grasses.