The association of the rabies glycoprotein with liposome (immunosome) induces an in vitro specific release of interleukin 2

BALB/c mice were primed by receiving a unique intraperitoneal injection of rabies virus antigens presented as complete inactivated virus (P.V. strain) or as purified glycoproteins either in the aggregated form or in physical combination with liposomes (i.e., in the form of "immunosomes"). The splenocytes of these mice were restimulated, 6-15 days after priming, in culture with rabies virus antigens, and antigen-specific IL-2 production was measured. It was found that rabies antigens presented as immunosomes were as active as the inactivated virus, whereas equivalent amounts of purified glycoproteins were inactive. The optimal amounts of rabies immunosomes used for priming was found to be 0.5 to 0.05 micrograms per mouse.     

Alleviation of water and osmotic stress-induced changes in nitrogen metabolizing enzymes in <Emphasis Type="Italic">Triticum aestivum</Emphasis> L. cultivars by potassium

Present communication reports laboratory and pot experiments conducted to study the influence of water and osmotic stress on nitrogen uptake and metabolism in two wheat (Triticum aestivum L) cultivars with and without potassium supplementation. Polyethylene glycol 6000-induced osmotic stress/restricted irrigation caused a considerable decline in the activity of nitrate reductase, glutamate synthase, alanine and aspartate aminotransferases, and glutamate dehydrogenase. Potassium considerably improved nitrogen metabolism under normal water supply conditions and also resulted in amelioration of the negative impact of water and osmotic stresses indicating that potassium supplementation can be used as a potential tool for enhancing the nitrogen use efficiency in wheat for exploiting its genetic potential.     

Native and Artificial Reticuloplasmins Co-Accumulate in Distinct Domains of the Endoplasmic Reticulum and in Post-Endoplasmic Reticulum Compartments

We compared the subcellular distribution of native and artificial reticuloplasmins in endosperm, callus, and leaf tissues of transgenic rice (Oryza sativa) to determine the distribution of these proteins among endoplasmic reticulum (ER) and post-ER compartments. The native reticuloplasmin was calreticulin. The artificial reticuloplasmin was a recombinant single-chain antibody (scFv), expressed with an N-terminal signal peptide and the C-terminal KDEL sequence for retrieval to the ER (scFvT84.66-KDEL). We found that both molecules were distributed in the same manner. In endosperm, each accumulated in ER-derived prolamine protein bodies, but also in glutelin protein storage vacuoles, even though glutelins are known to pass through the Golgi apparatus en route to these organelles. This finding may suggest that similar mechanisms are involved in the sorting of reticuloplasmins and rice seed storage proteins. However, the presence of reticuloplasmins in protein storage vacuoles could also be due to simple dispersal into these compartments during protein storage vacuole biogenesis, before glutelin deposition. In callus and leaf mesophyll cells, both reticuloplasmins accumulated in ribosome-coated vesicles probably derived directly from the rough ER.     

How to contend with paraphyly in the taxonomy of the delphinine cetaceans?

Molecular phylogenetic analyses conducted over the past 15 yr have consistently had difficulties resolving relationships among the cetacean species in the subfamily Delphininae. In addition, paraphyly of the genera Tursiops and Stenella in these molecular phylogenies has been a recurrent problem since the first appearance of such a phylogeny in 1999, suggesting that these genera do not accurately reflect the evolutionary relationships of the species they contain. Morphological analyses have not resolved the issues. The genera in Delphininae originated in the 19th Century on questionable morphological grounds. The species were nearly all originally described in the genus Delphinus of Linnaeus. Recent molecular phylogenies based on various mitochondrial and nuclear DNA markers have suggested a wide range of possible relationships among these taxa, and several authors have suggested synonymizing all the taxa (Lagenodelphis, Stenella, Sousa, and Tursiops) under Delphinus. Until molecular and/or morphological analyses adequately sort out relationships in this very recently radiated group, one possible solution indeed would be to merge all the delphinine genera with Delphinus. Implications of such a move and alternatives are discussed.

Editor's Note: Papers from past Norris Award winners have primarily been a revised or reduced version of the actual presentation given as a plenary talk at the biennial conference. Dr. Perrin requested being allowed to take a topic from his presentation and expand on it to present a set of ideas in the form of an essay that could pass the rigors of the peer‐review process. As a result, this Norris Award paper has undergone peer‐review and has taken longer than usual for a Norris Award paper to appear in the journal following its presentation at the biennial conference. It also has co‐authors, with varying opinions on the issues discussed in the essay, to cover appropriately and more thoroughly those components of the paper that required additional expertise. I believe this approach has produced an excellent, thought‐provoking essay and is an approach that should be available to future Norris Award winners if they so choose to take it. Since this essay is meant to elicit dialogue, comments are welcome and will be considered for publication in Letters to the Editor.

     

Seasonal variation in marine phytoplankton and ice algae at a shallow antarctic coastal site

The phytoplankton population near Davis, Vestfold Hills, Antarctica was monitored throughout 1982. Chlorophyll-a determinations and counts of living cells in both the water column and sea ice demonstrated a marked seasonality in phytoplankton abundane and species composition. From April to October nanoplanktonic organisms contributed most of the chlorophyll-a in both the sea ice and water column. Blooms of diatoms occurred in May, November and December in the bottom of the sea-ice and in January and February in the water column. Phaeocystis pouchetii was dominant during December in the water column. Large numbers of dead diatoms were found in winter. The concentrations of nitrate, dissolved inorganic phosphate and dissolved silicate increased throughout the year until December, when the concentrations of nitrate and silicate fell sharply, followed a month later by a reduction in phosphate concentration. The diversity of phytoplankton was greatest during the summer months.     

Impaired glucose homeostasis in mice lacking the alpha1b-adrenergic receptor subtype

To assess the role of the alpha1b-adrenergic receptor (AR) in glucose homeostasis, we investigated glucose metabolism in knockout mice deficient of this receptor subtype (alpha1b-AR-/-). Mutant mice had normal blood glucose and insulin levels, but elevated leptin concentrations in the fed state. During the transition to fasting, glucose and insulin blood concentrations remained markedly elevated for at least 6 h and returned to control levels after 24 h whereas leptin levels remained high at all times. Hyperinsulinemia in the post-absorptive phase was normalized by atropine or methylatropine indicating an elevated parasympathetic activity on the pancreatic beta cells, which was associated with increased levels of hypothalamic NPY mRNA. Euglycemic clamps at both low and high insulin infusion rates revealed whole body insulin resistance with reduced muscle glycogen synthesis and impaired suppression of endogenous glucose production at the low insulin infusion rate. The liver glycogen stores were 2-fold higher in the fed state in the alpha1b-AR-/- compared with control mice, but were mobilized at the same rate during the fed to fast transition or following glucagon injections. Finally, high fat feeding for one month increased glucose intolerance and body weight in the alpha1b-AR-/-, but not in control mice. Altogether, our results indicate that in the absence of the alpha1b-AR the expression of hypotalamic NPY and the parasympathetic nervous activity are both increased resulting in hyperinsulinemia and insulin resistance as well as favoring obesity and glucose intolerance development during high fat feeding.     

Experimental evidence of a deleterious soil microflora associated with Norway spruce decline in France and Germany

Norway spruce (Picea abies (L.) Karst.) seedlings were grown in a glasshouse pot experiment in soils from 11 declining and 7 healthy spruce stands from France and Germany. In soils from 9 declining stands, seedlings showed decline symptoms (needle yellowing). Soil pasteurization suppressed the symptoms, and reinoculation of the pasteurized soil with a rhizospheric extract from the corresponding stand re-induced yellowing. This suggests that a deleterious soil microflora is associated with spruce decline. The occurrence of this microflora seems to be correlated with the main chemical characteristics of the soils (low pH, low saturation of the adsorbing complex, low exchangeable Ca²⁺ and Mg²⁺, and high level of exchangeable Al). ei]R F Huettl     

Effects of cognitive abilities on metapopulation connectivity

Connectivity among demes in a metapopulation depends on both the landscape's and the focal organism's properties (including its mobility and cognitive abilities). Using individual‐based simulations, we contrast the consequences of three different cognitive strategies on several measures of metapopulation connectivity. Model animals search suitable habitat patches while dispersing through a model landscape made of cells varying in size, shape, attractiveness and friction. In the blind strategy, the next cell is chosen randomly among the adjacent ones. In the near‐sighted strategy, the choice depends on the relative attractiveness of these adjacent cells. In the far‐ sighted strategy, animals may additionally target suitable patches that appear within their perceptual range. Simulations show that the blind strategy provides the best overall connectivity, and results in balanced dispersal. The near‐sighted strategy traps animals into corridors that reduce the number of potential targets, thereby fragmenting metapopulations in several local clusters of demes, and inducing sink–source dynamics. This sort of local trapping is somewhat prevented in the far‐sighted strategy. The colonization success of strategies depends highly on initial energy reserves: blind does best when energy is high, near‐sighted wins at intermediate levels, and far‐sighted outcompetes its rivals at low energy reserves. We also expect strong effects in terms of metapopulation genetics: the blind strategy generates a migrant‐pool mode of dispersal that should erase local structures. By contrast, near‐ and far‐sighted strategies generate a propagule‐pool mode of dispersal and source–sink behavior that should boost structures (high genetic variance among‐ and low variance within local clusters of demes), particularly if metapopulation dynamics is also affected by extinction–colonization processes. Our results thus point to important effects of the cognitive ability of dispersers on the connectivity, dynamics and genetics of metapopulations.