The Purification and Characterization of Two Groups of Storage Proteins (Secalins) from Rye (Secale cereale L.)

Two groups of polypeptides, which together represented over90% of the secalin fraction, were purified by ion exchange chromatographyand gel filtration. These fractions had molecular weights of40 000 and 75 000 by SDS-PAGE and 33 000 and 54 000 by sedimentationequilibrium ultracentrifugation respectively. Isoelectric focusingshowed that each fraction contained a number of polypeptides.Amino acid analysis showed that the two groups had similar compositionswith high glutamate + glutamine and proline and low lysine.The N-terminal sequences of the two groups were identical at17 of the first 20 positions and were similar to those reportedfor ₂ and ₃-gliadins of wheat. Both groups had C-terminal histidine.These results are discussed in relation to prolamin evolutionand homology in barley, rye and wheat.     

Development of Eimeria funduli in Fundulus heteroclitus1

Laboratory-reared Fundulus grandis and F. heteroclitus were experimentally infected with Eimeria funduli by being fed Palaemonetes pugio (grass shrimp) collected from endemic areas. Histological sections were made of heart, liver, hepatopancreas, spleen, gall bladder, kidney, intestine, peri-intestinal fat, reproductive organs, and brain from F. grandis sacrificed at 1, 2, 6, 12, 18, and 24 h and from F. heteroclitus at 5, 6, 9, 14, 19, 24, 29, 34, 39, and 44 days after consuming naturally infected shrimp. We first found merogonous stages at day 9 postinfection (p.i.). No developmental stages of the parasite could be positively identified in the tissues of experimentally infected fish prior to day 9 p.i. Mature meronts were found 14 days p.i. The majority contained 8–16 (mean, 13) merozoites, but a few meronts had 18–26 (22) merozoites. Gamonts first appeared on day 14, were mature by day 19, and fertilization was completed by day 24 p.i. After sporoblast formation, sporopodia appeared during sporocyst wall formation, between days 24 and 29 p.i. Sporozoite formation was completed by day 44 p.i. in most sporocysts. Most endogenous stages occurred in hepatocytes; however, pancreatic and spleen cells were sometimes infected with gamonts.     

Elevated CO2 and conifer roots: effects on growth, life span and turnover

Elevated CO₂ increases root growth and fine (diam. 2 mm) root growth across a range of species and experimental conditions. However, there is no clear evidence that elevated CO₂ changes the proportion of C allocated to root biomass, measured as either the root:shoot ratio or the fine root:needle ratio. Elevated CO₂ tends to increase mycorrhizal infection, colonization and the amount of extramatrical hyphae, supporting their key role in aiding the plant to more intensively exploit soil resources, providing a route for increased C sequestration. Only two studies have determined the effects of elevated CO₂ on conifer fine-root life span, and there is no clear trend. Elevated CO₂ increases the absolute fine-root turnover rates; however, the standing crop root biomass is also greater, and the effect of elevated CO₂ on relative turnover rates (turnover:biomass) ranges from an increase to a decrease. At the ecosystem level these changes could lead to increased C storage in roots. Increased fine-root production coupled with increased absolute turnover rates could also lead to increases in soil organic C as greater amounts of fine roots die and decompose. Although CO₂ can stimulate fine-root growth, it is not known if this stimulation persists over time. Modeling studies suggest that a doubling of the atmospheric CO₂ concentration initially increases biomass, but this stimulation declines with the response to elevated CO₂ because increases in assimilation are not matched by increases in nutrient supply.     

Adaptation of Avian Eggs to Incubation Period Variability Around Allometric Regressions Is Correlated with Time

Many morphological and physiological parameters of avian eggsare known to be correlated with fresh egg weight, i.e, to exhibitallometric relationships. It has been predicted that part ofthe variability around some of these allometric relationshipsis the result of adaptations to incubation periods of differentlengths. I performed multiple regressions of three of theseparameters (the rate of water loss in the nest, conductanceof the shell to gases and the rate of O₂ consumption just priorto hatching) versus weight and incubation period to test thesepredictions. All these parameters were significantly correlatedwith weight and for eggs of the same weight inversely correlatedwith the length of the incubation period. Other investigatorshave reported allometric interrelations between weight, lifespan and other parameters. For example the average number ofheartbeats is the same in mammals of all weights. The kind ofinterrelation reported in this study appears similar to thiskind of allometric interrelation but is actually quite differentbecause it concerns organisms of the same weight. I refer tothis kind of interrelation between various parameters for eggsof the same weight as an isometric interrelation. The two kindsof interrelations are quite independent the existence of anallometric interrelation does not prove the existence of anisometric interrelation.     

Testing for MacArthur-Wilson Equilibrium with the Arthropods of the Miniature Spartina Archipelago at Oyster Bay, Florida

SYNOPSIS. The unique features of the MacArthur-Wilson modelof equilibrium biogeography are the immigration and extinctioncurves. In the model, the immigration rate for each island isnegatively correlated with species number, and island extinctionrate is positively correlated with species number. Direct tests of the sign and statistical significance of immigrationand extinction curves were done, with data on arthropods oftiny Spartina alterniflora islets, in north Florida. Rey (1981)defaunated six islets in the spring, then censused the recolonizationweekly, for one year. Two control islets and a mainland plotwere also censused. Distinct tendencies in favor of MacArthur-Wilsoncorrelations were present for both immigration and extinction.But sufficient extraneous variation occurs in immigration andextinction rates to make correspondence to MacArthur-Wilsoncurves statistically non-significant, unless probabilities arecombined among islands. Thus, mathematical deductions from theMacArthur-Wilson model, which treat the curves as deterministiclines with no variance, are less appropriate than approachesthat incorporate stochastic variation. The study of community patterns, by models such as the MacArthur-Wilsonmodel, are not a substitute for careful autecological studies.Mechanisms of colonization and co-existence are only dimly hintedat by gross community patterns.     

Poly(Ethylene Oxide), a New Slowing Agent for Protozoa

SYNOPSIS The water-soluble, viscoelastic resin Polyox® (WSR 301), a poly(ethylene oxide) of high molecular weight (4 million) is introduced as a new slowing agent for protozoa. Generally, as the kinetic viscosity of the resin increased from 0.25% to 1% (w/v), the swimming velocity of Euglena gracilis, Didinium nasutum, Paramecium aurelia, Blepharisma undulans , and Prorodon platyodon decreased. The 1.0% solution had the highest viscosity and decreased velocity more effectively than 1.0% methyl cellulose and Protoslo® solutions. The Polyox solutions differed from those of methyl cellulose and Protoslo by having, in addition to viscous drag, an elastic recoil that pulled the protozoa backwards when their swimming efforts stopped. The toxicity of these slowing agents was determined using 10 P. aurelia /test slide preparation. Paramecium numbers decreased in 1.0% methyl cellulose and Protoslo to nearly zero by 24 hr; in Polyox, not only were most of these ciliates alive after 24 hr, but many survived for 96 hr and divisions occurred in 0.25% and 0.50% solutions.     

A phylogenetic reconstruction of the Ichneumonoidea (Hymenoptera) based on the D2 variable region of 28S ribosomal RNA

The D2 variable region of 28S rRNA was sequenced in a wide range of Ichneumonoidea to provide the first comprehensive phylogenetic reconstruction of this superfamily. The two constituent families (Braconidae and Ichneumonidae) were each found to contain a single well-supported clade dominated by the more plesiomorphic life history strategies (idiobiosis, ectoparasitism and attacking endoephytic hosts). In the Braconidae this clade corresponds to the morphologically-defined group called the cyclostomes. In the Ichneumonidae the clade unites for the first time the pimpliformes ( sensu Wahl) with most of the phygadeuontoid subfamilies and several small taxa including Adelognathus and Euceros . Relationships among the remaining, more biologically-derived, subfamilies were less well resolved, but included among the Braconidae a well-supported microgastroid clade and strong evidence for a sister group relationship between the Agathidinae and Sigalphinae.