'Anemotactic' flight paths of tsetse flies in relation to host odour: a preliminary video study in nature of the response to loss of odour

ABSTRACT. Free-flying, wild Glossina pallidipes Aust. and G. morsitans Westw. were video-recorded in the field in Zimbabwe as they flew out of air permeated with host odour (camera 2.5 m up, looking down at the ground). Analysis of the flight tracks supports the proposal of Bursell (1984) that tsetse flies attracted to an invisible source of host odour respond weakly if at all to wind direction while in flight: on losing contact with the odour the flies made a sharp turn that was uncorrelated with wind direction. The size of the turn varied considerably, with a marked discontinuity in the log-survivorship curve at 120° (a fly which had turned through at least 120° was 5 times as likely to stop the turn as a fly which had turned <120°). Over half the flies made turns of >90° (and <2 m diameter) within the 2×2.5 m field of view of the camera. It is suggested that these turns initially served to arrest the upwind progress of the fly, with the size of the turn determining the degree to which the fly backtracked towards where it last detected odour or continues cross-wind. Mean flight speed was c. 5 ms^-1 (min. 2.5, max. probably 7ms^-1).     

Coccidian Parasites (Apicomplexa: Eimeriidae) of Nerodia spp. (Serpentes: Colubridae), with a Description of a New Species of Eimeria

Eimeria conanli n. sp. (Apicomplexa: Eimeriidae) is described from intestinal contents and feces of Nerodia erythrogaster transversa and N harteri harteri from northcentral Texas. Oocysts of the new species are ellipsoid in shape. 17.9 × 13.0(15–21 × 12–15) μm, with a smooth, thin, single-layered wall; shape index 1.4 (1.2–1.5). One to several (usually 2) polar granule(s) and an oocyst residuum are present, but a micropyie is absent. Sporocysts are elongate, 12.9 × 5.2 (13–15 × 5–6) -m, apparently without a true Stieda body structure. Each sporoeyst contains an ellipsoid residuum, 3.9 × 3.2 (3–6 × 2–4) μm, and elongate sporozoites, 11.4 × 2.5 (10–14 × 2–3) μm in situ, each with a spherical or subspherical anterior refractile body and spherical to ellipsoid posterior refractile body. In addition to the new species, oocysts of 4 previously described eimerians from colubrid snakes were found in these hosts.     

Homologies to the tomato endopolygalacturonase gene in the peach genome

Abstract. Peach endopolygalacturonase was isolated from the mesocarp tissue of soft ripe, freestone peach fruit, but was not detectable in mature pre-ripening fruit. It is a basic protein with a M_r of approximately 45000 Da, and cross-reacts with antibody to tomato endopolygalacturonase. Using a cDNA to the tomato enzyme as a probe, a fragment of peach genomic DNA was isolated which encoded about 50% of the peach enzyme. The nucleotide sequence of the fragment was determined and the amino acid sequence of part of the peach endopolygalacturonase peptide derived. Coding regions of the peach gene show extensive homology with related regions of the tomato gene. Introns are dissimilar. Endopolygalacturonase activity occurs in ripe 'freestone'peaches but not in the firmer 'clingstone'varieties. Hybridization studies identified a similar gene fragment in freestone, semi-freestone and clingstone peach varieties.     

Two forms of exopolygalacturonase increase as peach fruits ripen

Abstract. Freestone peach cultivars are distinguished from clingstone cultivars by a more extensive softening of the mesocarp tissue, and by the separation of mesocarp and endocarp during ripening. Cultivars of both types have been reported to develop exopolygalacturonase activity during ripening, but the enzyme has not been characterized in any detail. During development of freestone peaches ( Prunus persica L. var Coronet), two exopolygalacturonase enzymes were detected 42, 65 and 85 d after full bloom and in ripe fruit. During ripening one enzyme (exoPG 1) increased 36-fold and the other (exoPG 2) 90-fold but exoPG 2 accounted for a 73% of the total activity in ripe fruit. ExoPG 1 was purified 24-fold and exoPG 2 540-fold. ExoPG 2 is a slightly acidic glycoprotein. ExoPG 1 and exoPG 2 differ slightly in their pH optima and in their responses to calcium: each produces monogalacturonic acid as a reaction product. Similar enzymes were found in Flavorerest, a semi-freestone peach.     

Salt-tolerance in plants. I. Ions, compatible organic solutes and the stability of plant ribosomes

Abstract Polysomes and ribosomes recovered from a number of plant species were tested for stability when incubated at 25°C in salt solutions in the absence of ATP and initiation factors. Stability was assessed by sucrose density gradient analysis. The stability was inversely proportional to salt concentrations above 125 mol m⁻³ KCl. Polysomes were less stable in the presence of Na⁺ than K⁺ salts, and were much less stable in Cl⁻ than in acetate salts. Polysomes from Triticum aestivum. Hordeum vulgare, Capsicum annuum, Helianthus annuus. Pisum sativum, Atriplex nummularia, Beta vulgaris, Cladophora sp., Enteromorpha sp. and Corallina cuvieri were similarly sensitive to KCl. Polysomes from Ulva lactuca were more sensitive than the other species. Cytoplasmic and plastid polysomes from T. aestivum were similarly unstable in 500 mol m⁻³ KCl. Unprogrammed ribosomal subunit couples from T. aestivum, B. vulgaris and U. lactuca showed Mg²⁺-dependent conformational instability and dissociation in KCl. Slight differences in ribosomal stability were observed between species, but these were unrelated to the salt tolerances of the plants. The ‘compatible’ organic solutes, glycinebetaine and proline, failed to reduce ion-induced instability. Ribosome yield and polysome profiles were similar in leaves of B. vulgaris containing significantly different levels of both Na⁺ and Cl⁻ after growth in media containing 50 or 200 mol m⁻³ NaCl. The results are consistent with the hypothesis that plants maintain a cytoplasmic solute environment that is compatible with ribosomal stability.     

Succession following wildfire in coastal heathland (Nadgee Nature Reserve N.S.W.)

Changes in coastal heath vegetation were measured for 6 years following a wildfire and the data compared with the pre-fire vegetation. For the first 2 years changes were related to time; after that environmental factors dominated the process of regeneration. During the first 4 years plant species spread rapidly and maximum species diversity per plot was reached 4 years after the fire. About the same time many species consolidated their position in the community; this being shown by cover levels greater than before the fire for some species. Six years after the fire the vegetation is still dynamic and very different when compared with the heath before burning.