Trail Marking by the Larva of the Madrone Butterfly Eucheira socialis and the Role of the Trail Pheromone in Communal Foraging Behavior

The larva of the Madrone butterfly Eucheira socialis (Lepidoptera: Pieridae) secretes a trail pheromone from the ventral surface of the posterior tip of its abdomen. Caterpillars mark trails by bringing the secretory site into brief contact with the substrate during a locomotive cycle. Foragers mark most heavily when they move onto new branches and little, if at all, when they move over established trails or when they return to the communal shelter after feeding. The caterpillars make careful comparisons of alternative pathways at choice points and select newer and stronger trails over older and weaker trails. Differential marking of new and established trails during nightly forays, coupled with sensory discrimination of trails by strength and age, leads colonies to abandon old trails in favor of new trails. When applied at a rate as low as 2.5 × 10 ^–10 g/mm, caterpillars followed synthetic trails prepared from 5-cholestane-3-one, a trail pheromone previously reported from the tent caterpillars (Malacosoma spp.). Although both Eucheira and Malacosoma mark with the tip of the abdomen and have near-identical sensitivites to 5-cholestane-3-one, our study shows that Eucheira employs a relatively unsophisticated system of trail-based communication and does not recruit to food. The trail-based communication system of Eucheira appears to represent an early stage in the evolution of cooperative foraging that is derived from, and motivationally linked to, conflict behavior.     

The preparation of pregnancy urine for an estrogen profile.

A method is described for purifying the estrogen content of pregnancy urine with little loss of the labile estrogens. The procedure makes use of the initial 50-fold purification effected by their precipitation whith ammonium sulphate, with simultaneous elimination of most urinary corticosteroids and 50--60% of urinary ketosteroids. It also employs the antioxident ascorbic acid as an additive in most stages of the procedure. The mild organic-solvent-HIO partition system of Brown is used for separating the strongly polar, 2including all "labile" estrogens, and of the weakly polar estrogens, from neutral steroids. The remaining neutral steroid still interfering with the assays were removed by an ascorbic acid treated ion exchange resin (AG 1). The final residues were revealed by mass-spectroscopy to consist almost solely of estrogens. Gas-liquid chromatography in which just 2 chromatograms are required yields a total of 12 "estrogen" peaks (for 12 estrogens which are excreted in amounts greater than 0.1 mg/day) in normal pregnancy urine, including all the known labile estrogens. Identification as estrogen for all but a few minor peaks of the gas chromatogram was obtained by mass-spectroscopy. The practical significance of the method lies in the fact that some labile estrogens are much more important in the estrogen metabolism of pregnant and nonpregnant women than heretofore generally thought.     

Prostaglandin synthesis in spleen cell cultures of mice injected with Corynebacterium parvum.

Spleen cells of C57BL/6 mice produced high amounts of PGE in vitro when tested 5 to 10 days after injection of heat-killed C. parvum organisms. Little or no PGE was produced by spleen cells from untreated mice or from mice injected with a strain of coryneform bacteria that does not stimulate the lymphoreticular system of mice. Significant release of PGE from spleen cells of C. parvum injected mice could be detected as early as 30 min after initiating the cultures and maximal levels were usually seen after 48 hr. Treatment by indomethacin completely abolished this PGE production. Removal of the adherent population from the spleen cell suspension resulted in markedly decreased levels of PGE, but PGE release of the remaining population was never completely abolished. These data suggest that the cells responsible for most of the PGE synthesis in this system were adherent cells, presumably macrophages. The levels of PGE produced in spleen cells of C. parvum-treated mice were further increased by in vitro addition of C. parvum. This effect could also be observed after addition of zymosan particles indicating that it was not an immunologically specific effect. The reported data suggest that prostaglandins may represent important mediator molecules of the described immunostimulatory and immunosuppressive effects of C. parvum.     

Bottom dynamics in lakes

A proper understanding of the bottom dynamic conditions (erosion, transportation, accumulation) in lakes is essential in most sedimentological contexts. Fine cohesive materials generally dominate the open water areas, whereas coarser deposits (sand, gravel) dominate shallow regions where erosion and transportation of fine materials prevail. At present, there is no physical model available which describes the linkage between the energy content of the water-mass and the capacity for sediment entrainment in open water areas. Water-mass energy depends on, e.g. wind direction, duration, velocity, fetch, and the presence of a thermocline. Entrainment depends on, e.g. density, compaction, water and organic content of the sediments and the number and type of bottom fauna. Four different methods are used to determine bottom dynamics, two aresite typical and two arelake typical.Site andlake typical methods each include one method based on collected field data and one based on theoretical data. One method, the cone apparatus, is presented for the first time. It consists of two cones, one of which has a narrow angle and the other a wide angle, which are zero adjusted at the sediment surface before being released to penetrate the sediments. The differential cone penetration, refered to as the penetration ratio, is used to indicate the degree of surficial sediment compaction. This simple, inexpensive instrument provides quantitative data on physical sediment characteristics which may be related to bottom dynamic conditions.     

Acclimatizing micropropagated black cherry by comparison with half-sib seedlings

Black cherry ( Prunus serotina Ehrh.) plantlets were cultured in vitro, transferred to potting mixture and evaluated for 8 weeks for acclimatization to a varying, but controlled environment. Whole plantlet growth and water relations were monitored and compared to seedlings of comparable size of the same maternal genotype grown under different conditions, but given the same pretest environment. At one week ex vitro. gravimetrically determined leaf conductance of plantlets was high, but became closer to that of seedlings in both magnitude and diurnal pattern as acclimatization progressed. By 8 weeks, leaf conductance of plantlets was nearly identical to that of seedlings, but the xylem water potential of the plantlets was significantly less. Logarithmic regressions of shoot vs root dry weight indicated that seedlings were allocating twice as much dry matter to shoot than to root growth compared to 4- and 8-week plantlets. Over the same period, stomatal densities of both seedlings and plantlets decreased and stomatal pore lengths increased. Multiple adventitious roots of plantlets emerged from a single site just below the root collar whereas secondary or lateral roots of seedlings originated acropetally along the central root axis. Leaf conductance of plantlets at 8 weeks was similar to that of seedlings indicating satisfactory acclimatization. The larger relative root growth rate of plantlets compared to the shoot, however, was associated with lower stem xylem water potential. The anomaly may be a consequence of the method of in vitro root formation. Plantlet growth rates were lower than growth rates of seedlings and their leaf area was correspondingly less.     

Seasonal thermal tolerance in marine Crustacea

Seasonal values of the critical thermal maximum (CTMax) of eight species of adult marine Crustacea from temperate latitudes were measured and found to range between 20 and 34 °C. The extent to which CTMax was dependent on acclimatization varied with species but for most of the species studied, summer-captured animals had significantly higher CTMax values than winter-captured animals. Heat shock resulted in an increase in thermotolerance in most species in winter-captured animals, but a different pattern was found for summer-captured animals. Then, only Cancer pagurus and Pagurus bernhardus showed a positive increment of CTMax on heat shock. Test for Serial Independence analysis indicated no significant phylogenetic autocorrelation between CTMax values in winter or summer-captured animals. Temperature measurements taken by remote data loggers in the intertidal zone of the North-East coast of England are reported. These suggest that several species, whose distribution extends into the intertidal zone, may experience temperatures close to their CTMax in summer.     

A three-stage micropropagation system for a novel color morph of the wildflower, <Emphasis Type="Italic">Porteranthus trifoliatus</Emphasis> (L.) Britt

A three-stage micropropagation system was devised for Porteranthus trifoliatus ‘Pink Profusion’, a cultivar distinguished from the wild type by its pink flowers, purple stems and darker reddish leaves. Nodes of young shoots were used as explants, disinfested, and placed on several different Murashige and Skoog’s (MS) media formulations containing two levels of indole-3-butyric acid (IBA) and four levels of benzylaminopurine (BAP) in a factorial combination. An optimal number of commercially-usable shoots was achieved with BAP concentrations between 10 μM and 30 μM, while the addition of IBA made no significant difference in the number of shoots produced. Proliferated shoots could be rooted ex vitro without auxin treatment.     

A general model of error-prone PCR

In this paper, we generalize a previously-described model of the error-prone polymerase chain reaction (PCR) reaction to conditions of arbitrarily variable amplification efficiency and initial population size. Generalisation of the model to these conditions improves the correspondence to observed and expected behaviours of PCR, and restricts the extent to which the model may explore sequence space for a prescribed set of parameters. Error-prone PCR in realistic reaction conditions is predicted to be less effective at generating grossly divergent sequences than the original model. The estimate of mutation rate per cycle by sampling sequences from an in vitro PCR experiment is correspondingly affected by the choice of model and parameters.     

Effects of photon flux density on the morphology,photosynthesis and growth of a CAM orchid, <Emphasis Type="Italic">Doritaenopsis</Emphasis> during post-micropropagation acclimatization

Micropropagated plantlets are fragile and often lack sufficient vigour to survive the acclimatization shock during transplantation to the soil. Effects of photosynthetic photon flux densities (PPFDs) on growth, photosynthesis and anatomy of micropropagated Doritaenopsis were studied after 4 months of acclimatization in a greenhouse at 25 °C. The plantlets were transferred to three different PPFDs for four months, i.e. low light (175), intermediate light (270) and high light (450 mol m^–2 s^–1). For most of the growth parameters measured i.e. leaf length, leaf area, leaf width, fresh weight, dry weight, chlorophyll (Chl) a/b ratio, were greater for the intermediate light levels after 4 months of acclimatization. The only exception was leaf thickness, which was increased more under high light levels. Results showed that the survival of Doritaenopsis plantlets was greatest (90%) in low light and intermediate light (89%) compared with only (73%) at high light. However, at low light levels, pigment concentrations (chlorophyll a, b and total chlorophyll) were higher. Net CO₂ assimilation (A), stomatal conductance (g) and transpiration (E) were higher in plantlets grown at high level PPFD than at low after 4 months of acclimatization. Photosynthetic efficiency (Fv/Fm) decreased insignificantly; only at mid day for the high light treatment whereas leaf temperature and stomatal closure increased compared to low light. Scanning electron microscopic (SEM) images of leaves from acclimatized plantlets showed an increase in wax formation for the high light grown plantlets compared to those at low light. Microscopic analysis of acclimatized root sections showed highly developed multiseriate-velamen layers and higher root cell activity; while shoots had larger leaf air spaces than those of in vitro grown plantlets. These results suggest that physiological acclimation occurs at the intermediate PPFD (270 mol m^–2 s^–1) in Doritaenopsis compared to treatment at the high light level.