Restriction endonuclease EcoO109 from Escherichia coli H709c with heptanucleotide recognition site 5'-PuG/GNCCPy

A new restriction endonuclease, EcoO109, has been isolated from Escherichia coli H709c by polyethyleneimine (PEI) precipitation, DEAE-cellulose chromatography and heparin agarose chromatography. The yield was high, more than 3000 units/g of wet cells. The EcoO109 endonuclease recognizes and cleaves a nucleotide sequence of (formula: see text), in the presence of 10 mM Mg2+. The enzyme will be useful for structural analysis and molecular cloning of DNA because of the stability, high yield and easy handling of the producer strain.     

Aphytophagy in butterflies: its relationship to myrmecophily

The regular or obligate aphytophagy of certain lycaenid butterflies (Lepidoptera) is discussed within the framework of the most recent general classification of the family. A summary survey of all Lycaenidae known to be aphytophagous is presented, together with a brief account of cannibalism and other opportunistic aphytophagy exhibited by normally phytophagous butterflies. The range of food sources (plants, animals, excretions and regurgitations) exploited by lycaenids is reviewed with emphasis falling on the ecology of myrmecophilous early stages and the significance of their ant-related adaptations. Adult feeding and oviposition behaviour reveal further associations with ants. Specificity of lycaenid/ant relationships and the possible biological effects of aphytophagy on the Lycaenidae are discussed. Finally, speculations concerning the evolution of aphytophagy by these butterflies are critically presented.     

Chronobiological aspects of the host-parasite relationships between Biomphalaria glabrata and Schistosoma mansoni: cercarial production and infectivity, and growth kinetics of the host

In the Biomphalaria glabrata-Schistosoma mansoni association, variations in cercarial production, in cercarial infectivity, and in the growth of infected snails are rhythmic. These chronobiological aspects are correlated with the dynamics of the intramolluscan larval stages of the parasite during the course of the infection. Rhythmic variations in the growth kinetics of infected snails are interpreted in terms of host-parasite metabolic exchanges.     

Heydenius dominicus n. sp. (Nematoda: Mermithidae), a Fossil Parasite from the Dominican Republic

Heydenius dominicus n. sp. is described as a new species of fossil mermithid nematode from Dominican Republic amber. The species is represented by two specimens of parasitic juveniles that left their insect host and became embedded in the resin. The nematodes are associated with an adult male limoniid (Diptera: Limoniidae) and an adult female mosquito (Diptera: Culicidae). The parasites are thought to have emerged from the mosquito host. This is the first report of a fossil mermithid from a Neotropical area.     

Histopathology of Okra and Ridgeseed Spurge Infected with Meloidodera charis

Histological observations of okra Abelomoschus esculentus ''Clemson Spineless'' and ridgeseed spurge Euphorbia glyptosperma (a common weed) infected with Meloidodera charis Hopper, indicated that the juvenile nematode penetrated the roots intercellularly. Within 5 days after plant emergence the nematode positioned its body in the cortical tissue parallel to the vascular system. By 10 days after plant emergence the juvenile had extended its head into the vascular system and initiated giant cell formation, generally in protophloem tissue. Giant cells were one celled and usually multi-nucleate. Eggs were observed in the female body 30 days after plants emerged and juveniles were found within the female body by 40 days. Nematode development progressed equally in the root system of either host plant. Generally, throughout the nematode''s life cycle its entire body remained inside the cortical tissue of okra. In ridgeseed spurge, however, the posterior portion of the female erupted through the host epidermis as early as 15 days after plant emergence; only the head and neck remained embedded in the host. The nematode caused extensive tissue disruption in the cortical and vascular system of both plant species. Corn, Zea mays, was another host of the nematode.     

Behavioural response of spider mites (Tetranychus urticae) to induced resistance of cotton plants

ABSTRACT.

• 1 Spider mites (Tetranychus urticae Koch) given a choice between a cotton plant previously damaged by mites and an undamaged control preferentially moved to the control plant.
• 2 This host-choice behaviour was seen in adult female mites but not in immatures.
• 3 Adult females were not found to be significantly more fecund on control plants than on previously damaged plants, but the duration of this choice experiment precluded full assessment of effects on fecundity.
• 4 Mites responded very quickly, choosing previously undamaged plants without contacting or feeding on the test plants. This suggests that an olfactory response to a chemical substance(s) is involved.

     

Attachment may be a basis for specialization in oak aphids

ABSTRACT.

• 1 The potential role of tarsal attachment in host selection was studied in the specialist aphids Tuberculoides annulatus Hartig and Myzocallis schreiberi Hille Ris Lambers and Stroyan.
• 2 M.schreiberi could walk freely on its host, Quercus ilex and on Q.robur, whereas T.annulatus could walk freely on its host, Q.robur but had difficulty on Q. ilex.
• 3 Attachment to the rough-textured leaves of Q.robur was achieved by means of the pretarsal claws, and to the smooth upper surface of individual trichomes on the lower surface of Q.ilex using flexible pretarsal empodia.
• 4 Both behavioural and allometric differences can account for the inability of T.annulatus to grip onto Q.ilex.
• 5 The role of attachment by phytophagous insects in host plant resistance and selection is discussed.

     

Seasonal transmission ofRaphidascaris acus (Nematoda), a parasite of freshwater fishes,in definitive and intermediate hosts

Synopsis The seasonal transmission ofRaphidascaris acus was studied in two small lakes on Manitoulin Island, Ontario. Dragonfly nymphs and caddisfly larvae, acting as paratenic hosts, contained second-stage larvae. Several fishes, including percids and cyprinids, were intermediate hosts with second, third, and fourth-stage larvae in the liver. Yellow perch,Perca flavescens, was the most important of these. Intensities were up to 928 and increased with length and age of the perch; prevalence was 100%. Abundance ofR. acus tended to be higher in females but was not related to condition of the perch. Second-stage larvae were acquired from invertebrates in summer and developed to the fourth stage by November. They became surrounded by fibrous capsules during the next summer but remained alive for at least another year. The longevity of larvae in the intermediate host may ensure survival of the parasite through periods of low host abundance after winterkill. Northern pike,Esox lucius, was the definitive host. Abundance ofR. acus tended to be greater in larger pike but was not related to sex or condition of the fish. The parasite was acquired in late fall. Prevalence was 100% and mean intensities were over 200 in winter and spring, declining to 64–100% and less than 15, respectively, in summer. Mature worms were present from early spring through summer. Seasonality of infection in the definitive host is not attributable to seasonal availability of larvae in perch. Instead it may be controlled by timing of predation on perch and rate of development and longevity of the parasite. Transmission to pike apparently continues in summer. Low intensity may result from low recruitment rate and rapid turnover of the parasite population.     

Types of sesquiterpene-coumarin ethers from Achillea ochroleuca and Artemisia tripartita

In addition to known derivatives, four new sesquiterpene-coumarin ethers were isolated from the roots of Achillea ochroleuca and Artemisia tripartita and identified by ¹H and ¹³C NMR spectroscopy, including lanthanide induced shifts. The new compounds are isofraxidin derived ethers which differ from the previously described derivatives by ring cleavage and methyl migration within the terpenoid unit. The chemosystematic importance of sesquiterpene-coumarin ether accumulation within the two genera is briefly discussed.