Evaluation of the palatability of chrysomelid larvae containing anthraquinones to birds

Chrysomelid larvae of the subfamily Galerucinae, tribe Galerucini, are known to contain 1,8-dihydroxylated 9,10-anthraquinones. Since nonhydroxylated 9,10-anthraquinone is the active agent in several commercial products sold to protect seeds against birds, we suggested that the naturally occurring dihydroxylated anthraquinones of galerucine larvae may also act as protective devices against bird predation. Tits (Parus spp.) are potential predators of larvae of the tansy leaf beetle, Galeruca tanaceti, and the elm leaf beetle, Xanthogaleruca luteola. To investigate the palatability of these chrysomelid larvae to birds, we offered them with mealworms and Calliphora pupae, respectively, as controls in dual choice bioassays to eight singly kept, naive tits (five P. major and three P. ater individuals). The bioassays were limited to 5 days, during which larvae were offered daily for 2 h (X. luteola) and 3 h (G. tanaceti), respectively. Every day, the birds significantly avoided uptake of G. tanaceti and X. luteola. More than 98% of the control food was consumed daily, whereas the percentage of chrysomelid larvae totally eaten never surpassed 6.6% for G. tanaceti and 51.8% for X. luteola. In order to determine whether this avoidance was due to the anthraquinones of the chrysomelid larvae, mealworms and Calliphora pupae, respectively, were treated with these compounds in concentrations equivalent to the natural ones. Dual choice bioassays with treated and untreated prey were conducted, again for 5 days with a daily 2- or 3-h test period, respectively. The tits ate all or nearly all treated and untreated food items every day. However, during the 5-day test period the tits learnt to take up the control insects significantly earlier than the treated ones; the food containing anthraquinones was not consumed as readily as the control, which suggest aversive learning based on distastefulness. The efficiency of anthraquinones in protecting galerucine larvae against bird predation is discussed with special respect to learning behavior and factors which might delay or mask learning of avoidance.     

Effects of Motility and Adsorption Rate Coefficient on Transport of Bacteria through Saturated Porous Media

Three strains of Pseudomonas fluorescens with different motility rates and adsorption rate coefficients were injected into porous-medium reactors packed with l-mm-diameter glass spheres. Cell breakthrough, time to peak concentration, tailing, and cell recovery were measured at three interstitial pore velocities (higher than, lower than, and much lower than the maximal bacterial motility rate). All experiments were done with distilled water to reduce the effects of growth and chemotaxis. Contrary to expectations, motility did not result in either early breakthrough or early time to peak concentration at flow velocities below the motility rate. Bacterial size exclusion effects were shown to affect breakthrough curve shape at the very low flow velocity, but no such effect was seen at the higher flow velocity. The tendency of bacteria to adsorb to porous-medium surfaces, as measured by adsorption rate coefficients, profoundly influenced transport characteristics. Cell recoveries were shown to be correlated with the ratio of advective to adsorptive transport in the reactors. Adsorption rate coefficients were found to be better predictors of microbial transport phenomena than individual characteristics, such as size, motility, or porous-medium hydrodynamics.     

Sequential assignment of 1H, 13C and 15N resonances of human carbonic anhydrase I by triple-resonance NMR techniques and extensive amino acid-specific 15N-labeling

Summary The backbone NMR resonances of human carbonic anhydase I (HCA I) have been assigned. This protein is one of the largest monomeric proteins assigned so far. The assignment was enabled by a combination of 3D triple-resonance experiments and extensive use of amino acid-specific ¹⁵N-labeling. The obtained resonance assignment has been used to evaluate the secondary structure elements present in solution. The solution structure appears to be very similar to the crystal structure, although some differences can be observed. Proton-deuteron exchange experiments have shown that the assignments provide probes that can be used in future folding studies of HCA I.The chemical shift data have been deposited in the BioMagResBank in Madison, WI, U.S.A.     

Independent regulation of serologically distinct idiotypes in F1 hybrid mice

We have investigated the regulation of expression of two distinct intrastrain cross-reactive idiotypes, CRI_A and CRI_C, characteristic of anti-p-azophenylarsonate (anti-Ar) antibodies of the A/J and BALB/c strains, respectively, in (BALB/c x A/J)F₁ (CAF₁) mice. Such hybrid mice were found to synthesize antibodies with each idiotype when immunized against the Ar hapten group, although the expression of each was significantly reduced as compared with the parental strain. CAF₁ mice were pretreated with idiotypic-specific antibody reagents and subsequently hyperimmunized against the Ar hapten. Analysis of the idiotypes present in immune sera showed that suppression of either CRI did not concomitantly suppress the expression of the other. Alteration of the expression of one idiotype was not, however, without influence on the other; the expression of CRI_C was markedly enhanced in mice suppressed for CRI_A.Abbreviations used in this paper anti-Id(A/J) idiotypic-specific antibodies against A/J serum Ar-specific antibodies - anti-Id(BALB/c) idiotypic-specific antibodies against BALB/c serum Ar-specific antibodies - Ar p-azophenylarsonate - BGG bovine -globulin - BSA bovine serum albumin - CAF₁ F(BALB/c x A/J) - CFA complete Freund's adjuvant - CRIA the major cross-reactive idiotype of A/J Ar-specific antibodies - CRI_C the major cross-reactive idiotype of BALB/c Ar-speck antibodies - CRI_m the minor cross-reactive idiotype of A/J Ar-specific antibodies - DTH delayed-type hypersensitivity - HP hybridoma product(s) - KLH keyhole limpet hemocyanin     

Zeta potential of protoplasts from gravireacting maize roots

Protoplasts were isolated from cortical cells of the elongating zone of maize (Zea mays L. cv. LG 11) roots and submitted to microelectrophoresis. Significant and transient differences in zeta potential between protoplasts from upper and lower root sides were compared with the gravireaction and the differential elongation of these roots. The maximum difference in the zeta potential was obtained between protoplasts from the upper and lower cortical cells after 90 min, exactly the time of gravipresentation for which the maximum rate of gravireaction was observed. In addition, this almost corresponded to the time for which the difference between the elongation rates of upper and lower sides of the extending zone began to increase. Consequently, the changes in the charges of the plasmalemma of the cortical cells from the growing part of roots could be more or less directly related to the root graviresponse.     

Catecholamines in fetal pig plasma and the response to acute hypoxia and chronic fetal decapitation

Summary Dopamine, norepinephrine and epinephrine were measured by radioenzymatic assay in blood plasma samples drawn from the umbilical arteries of 30 anaesthetised Landrace pig fetuses. Just prior to term, the concentrations of dopamine (0.46±0.14 ng·ml^–1) and norepinephrine (1.74±0.60 ng·mg^–1) were lower than earlier in gestation, whereas epinephrine concentrations at term (0.80±0.31 ng·ml^–1) were similar to those at mid-gestation, intervening stages of gestation having higher levels of plasma epinephrine. Fetal hypoxia was induced by clamping the umbilical cord for 2 min and the catecholamines determined in arterial blood samples immediately thereafter, then again 3 min after removal of the clamp. Inconsistent effects of cord clamping on catecholamine levels were seen at 55 days, but thereafter, in all but one instance, the hormone levels were increased. Fetuses near term tended to respond less than fetuses at 75 and 96 days gestation (term=114±1 day). Catecholamines were also present in the circulation of fetuses decapitated at 42 days gestation and studied at 109±1 days. The average concentrations of dopamine (1.12±0.27 ng·ml^–1) and norepinephrine (8.23±3.04 ng·ml^–1) were greater than in intact fetuses, the plasma epinephrine levels being comparable to, or slightly higher than, those in intact fetuses. The results demonstrate that catecholamines are present in the circulation of the intact and decapitated pig fetus and that the actual concentrations and the type of response to umbilical cord clamping are dependent on gestation age.     

The carbonyl reactivity of 3-bromopyruvate and related compounds

The covalent hydration of β-halopyruvic acids and β-halopyruvamides has been investigated in the uv region by stopped-flow techniques. In aqueous solutions of β-bromopyruvate and related compounds, the geminal diol is the predominant form at all pH values. Kinetic investigations have also been carried out on these hydrations. General bases enhance the rate of approaching the equilibrium. Specific acid catalysis was not detected. In the water-catalyzed reaction of pyruvamides, the relationship between the equilibrium constants K and the rate constants of the forward reaction shows that the transition state is more productlike.