Comparing the physiological effects and function of larval feeding in closely‐related endoparasitoids (Braconidae: Microgastrinae)

Abstract The larvae of most endoparasitoid wasps consume virtually all host tissues before pupation. However, in some clades, the parasitoid larvae primarily consume haemolymph and fat body and emerge through the side of the host, which remains alive and active for up to several days. The evolutionary significance of this host‐usage strategy has attracted attention in recent years. Recent empirical studies suggest that the surviving larva guards the parasitoid broods against natural enemies such as predators and hyperparasitoids. Known as the ‘usurpation hypothesis’, the surviving larvae bite, regurgitate fluids from the gut, and thrash the head capsule when disturbed. In the present study, the ‘usurpation hypothesis’ is tested in the association involving Manduca sexta, its parasitoid Cotesia congregata, and a secondary hyperparasitoid Lysibia nana. Percentage parasitoid survival is higher and hyperparasitism lower when cocoons of C. congregata are attached to the dorsum of M. sexta caterpillars. Fat body contents in several associations involving solitary and gregarious parasitoids feeding on haemolymph and fat body are also compared. The amount of fat body retained in parasitized caterpillars varies considerably from one association to another. In M. sexta and Pieris brassicae, considerable amounts of fat body remain after parasitoid emergence whereas, in Cotesia kariyai and Cotesia rufricus, virtually all of the fat body is consumed by the parsasitoid larvae. The length of post‐egression survival of parasitized caterpillars differs considerably in several tested associations. In Pseudeletia separata, most larvae die within a few hours of parasitoid emergence whereas, in M. sexta, parasitized larvae live up to 2 weeks after parasitoid emergence. Larvae in other associations parasitized by gregarious and solitary endoparasitoids live for intermediate periods. The results are discussed in relation to the adaptive significance of different feeding strategies of immature parasitoids and of the costs and benefits of retaining the parasitized caterpillar in close proximity with the parasitoid cocoons.     

Effect of Adenine on Paramecium multimicronucleatum*

SYNOPSIS. The addition of adenine to the culture medium of Paramecium multimicronucleatum caused an inhibition of conjugation and fission and also an increase in the number of food vacuoles. The inhibition of conjugation was observed at the stage of adhesion of cell membranes. With adenine, the duration of fission was prolonged and L-shaped cells were formed. Adenine apparently repressed the excretion of food vacuoles and thus caused an accumulation of food vacuoles within the cells. All these effects were observed at similar concentrations of adenine higher than 2 mM. The addition of uridine to the adenine-containing medium reversed the inhibition of fission; conjugation and vacuole accumulation remained unaffected.     

A kinetic analysis of cadmium accumulation in a Cd hyper‐accumulator fern,Athyrium yokoscense and tobacco plants

Cadmium (Cd) accumulations in a Cd hyper‐accumulator fern, Athyrium yokoscense (Ay), and tobacco, Nicotiana tabacum (Nt), were kinetically analysed using the positron‐emitting tracer imaging system under two medium conditions (basal and no‐nutrient). In Ay, maximumly 50% and 15% of the total Cd accumulated in the distal roots and the shoots under the basal condition, respectively. Interestingly, a portion of the Cd in the distal roots returned to the medium. In comparison with Ay, a little fewer Cd accumulations in the distal roots and clearly higher Cd migration to the shoots were observed in Nt under the basal condition (maximumly 40% and 70% of the total Cd, respectively). The no‐nutrient condition down‐regulated the Cd migration in both species, although the regulation was highly stricter in Ay than in Nt (almost no migration in Ay and around 20% migration in Nt). In addition, the present work enabled to estimate physical and physiological Cd accumulation capacities in the distal roots, and demonstrated condition‐dependent changes especially in Ay. These results clearly suggested occurrences of species‐/condition‐specific regulations in each observed parts. It is probable that integration of these properties govern the specific Cd tolerance/accumulation in Ay and Nt.     

DNA binding of citrus dehydrin promoted by zinc ion

Dehydrins are hydrophilic proteins that accumulate during embryogenesis and osmotic stress responses in plants. Here, we report an interaction between citrus dehydrin Citrus unshiu cold-regulated 15 kDa protein (CuCOR15) and DNA. Binding of CuCOR15 to DNA was detected by an electrophoretic mobility shift assay, a filter-binding assay and Southwestern blotting. The binding was stimulated by physiological concentrations of Zn²⁺, but little stimulation occurred when other divalent cations, such as Mg²⁺, Ca²⁺, Mn²⁺, Ni²⁺ and Cu²⁺, were substituted for Zn²⁺. Ethylenediaminetetraacetic acid cancelled the Zn²⁺-stimulated binding. A binding curve and competitor experiments suggested that the DNA binding of CuCOR15 exhibited low affinity and non-specificity. Moreover, tRNA competed with the DNA binding. Histidine-rich domains and a polylysine segment-containing domain participated in the DNA binding. These results suggest that CuCOR15 can interact with DNA, and also RNA, in the presence of Zn²⁺. Dehydrin may protect nucleic acids in plant cells during seed maturation and stress responses.     

FIRST RECORD OF THE CIRRIPEDE GENUS STRAMENTUM (THORACICA, SCALPELLIFORMES) FROM THE UPPER CRETACEOUS OF JAPAN

Abstract:  The scalpelliform genus Stramentum is described from upper Turonian–Coniacian (Upper Cretaceous) strata in the Mikasa area, Hokkaido (Japan), documenting the first record of the genus from the north-west Pacific Realm. The single articulated skeleton, which is horizontally embedded in a dark grey laminated mudstone, is specifically indeterminate because capitular plates are missing. However, peduncular morphology resembles that of S. ( S .) pulchellum (Sowerby Jr), which has been described from the Cenomanian–Turonian of Europe. The present record from Japan demonstrates that this cirripede genus had a wider geographic distribution than previously assumed during the youngest phase of its radiation.     

The land–atmosphere water flux in the tropics

Tropical vegetation is a major source of global land surface evapotranspiration, and can thus play a major role in global hydrological cycles and global atmospheric circulation. Accurate prediction of tropical evapotranspiration is critical to our understanding of these processes under changing climate. We examined the controls on evapotranspiration in tropical vegetation at 21 pan-tropical eddy covariance sites, conducted a comprehensive and systematic evaluation of 13 evapotranspiration models at these sites, and assessed the ability to scale up model estimates of evapotranspiration for the test region of Amazonia. Net radiation was the strongest determinant of evapotranspiration (mean evaporative fraction was 0.72) and explained 87% of the variance in monthly evapotranspiration across the sites. Vapor pressure deficit was the strongest residual predictor (14%), followed by normalized difference vegetation index (9%), precipitation (6%) and wind speed (4%). The radiation-based evapotranspiration models performed best overall for three reasons: (1) the vegetation was largely decoupled from atmospheric turbulent transfer (calculated from Ω decoupling factor), especially at the wetter sites; (2) the resistance-based models were hindered by difficulty in consistently characterizing canopy (and stomatal) resistance in the highly diverse vegetation; (3) the temperature-based models inadequately captured the variability in tropical evapotranspiration. We evaluated the potential to predict regional evapotranspiration for one test region: Amazonia. We estimated an Amazonia-wide evapotranspiration of 1370 mm yr⁻¹, but this value is dependent on assumptions about energy balance closure for the tropical eddy covariance sites; a lower value (1096 mm yr⁻¹) is considered in discussion on the use of flux data to validate and interpolate models.     

生于Equisetum上的日本新记录种Stamnaria americana(英文)

对日本新记录种Stamnaria americana进行了描述和图示。尽管低温适宜该种子囊孢子的萌发,它在20℃生长最好。DNA序列分析的结果表明,其分类地位应该从柔膜菌科转入锤舌菌科。     

Retardation of testis development in the armyworm,Pseudaletia separata,parasitized by the braconid wasp,Cotesia kariyai

Summary

In order to complete growth and development, the endoparasitoid wasp, Cotesia (=Apanteles) kariyai, inhibits pupation of its armyworm host, Pseudaletia (=Leucania) separata. In host larvae retardation of testis and spermatocyst development caused by the parasitoid was also observed. The agents causing the retardation were found in the ovaries and venom of the female adult parasitoid. When an unparasitized male host larva was artificially injected with calyx fluid obtained from ovaries together with venom, it showed the same degree of developmental retardation of testes and spermatocysts as in natural parasitization. Testes implanted in isolated abdomens of healthy larvae did not increase in size by ecdysteroid stimulation after exposure to calyx fluid plus venom. It is suggested that both symbiotic polydnavirus existing in calyx fluid and venom in the parasitoid, C. kariyai, are responsible for the parasitic retardation of the male reproductive organs in the host, P. separata.     

Innovative use of controlled availability fertilizers with high performance for intensive agriculture and environmental conservation

A variety of slow release fertilizers, controlled release (availability) fertilizers (CAFs),and stability fertilizers have been developed in response to the serious drawbacks of the conventional fertilizers since the early 1960's. Of these fertilizers, CAFs which are coated with resin are consumed in the largest quantity in the world. Selecting CAFs with higher performance, the author will discuss about: 1) Innovation of agro-technologies for various field crops including new concepts of fertilizer application, 2) high yielding of field crops, 3) enhancing quality and safety of farm products, and 4) controlling the adverse effect of intensive agriculture on the environment.