Honeydew amino acids in relation to sugars and their role in the establishment of ant-attendance hierarchy in eight species of aphids feeding on tansy (Tanacetum vulgare)

Abstract. The ratio of the concentration of honeydew total amino acids to total sugars in the honeydew of eight species of aphids, all feeding on tansy, Tanacetum vulgare (L.), was determined and correlated with honeydew production and ant‐attendance. The honeydew of the five ant‐attended aphid species [Metopeurum fuscoviride (Stroyan), Trama troglodytes (v. Hayd), Aphis vandergooti (Börner), Brachycardus cardui (L.), Aphis fabae (Scopoli)] was rich in total amino acids, ranging from 12.9 to 20.8 nmol µL^?1 compared with the unattended aphid Macrosiphoniella tanacetaria (Kalt.) with only 3 nmol µL^?1. Asparagine, glutamine, glutamic acid and serine (all nonessential amino acids) were the predominant amino acids in the honeydew of all species. The total concentration of amino acids in the phloem sap of tansy was much higher (78.7 nmol µL^?1) then in the honeydew samples, and the predominant amino acids were glutamate (34.3%) and threonine (17.7%). A somewhat unexpected result was the finding that those aphid species with the highest total amino acid concentration in the honeydew always had the highest concentration of sugars. The lowest amino acid–sugar combined value was 104–28.8 nmol µL^?1 in the non ant‐attended species M. tanacetaria, and the highest value was an average of 270–89.9 nmol µL^?1 for the three most intensely attended aphid species M. fuscoviride, A. vandergooti and T. troglodytes. There is no evidence that any single amino acid or group of amino acids in the honeydew acted as an attractant for ant‐attendance in these eight aphid species. The richness of the honeydew (rate of secretion × total concentration of sugars), along with the presence of the attractant sugar melezitose, comprised the critical factors determining the extent of ant‐attendance of the aphids feeding on T. vulgare. The high total amino acid concentration in sugar‐rich honeydews can be explained by the high flow‐through of nutrients in aphids that are particularly well attended by ants.     

Einfluß von Epicoccum nigrum,Alternaria alternata,Mucor racemosus und Ulocladium chartarum auf die Protozoenpopulation im Pansen des Rindes (in vitro)

The influence of moulded hay (Alternaria alternata, Epicoccum nigrum, Mucor racemosus, Ulocladium chartarum) and the efficiency of Vitamin B1 substitution to cope these effects on rumen protozoa was investigated using the longterm rumen simulation technique (RUSITEC) for about 25 days. Moulded hay affected medium-sized protozoa to a different extent (Alternaria alternata: ?16 %, Epicoccum nigrum: ?27 %, Mucor racemosus: ?9 %, Ulocladium chartarum: +2 %). The vitamin B1 substitution had positive effects during the feeding of Mucor racemosus and Ulocladium chartarum.     

Plant responses to H2S and SO2 fumigation. I. Effects on growth, transpiration and sulfur content of spinach

Exposure of spinach (Spinacia oleracea L. cv. Monosa) to 0.25 μl l_?1 H₂S reduced the relative growth rate by 26, 47 and 60% at 15, 18 and 25°C, respectively. Shoot to root ratio decreased in plants fumigated at 18 and 25°C. Growth of spinach was not affected by a 2-week exposure to 0.10 or 0.25 μl l_?1 SO₂. Both H₂S and SO₂ fumigation increased the content of sulfhydryl compounds and sulfate. A 2-week exposure to 0.25 μl l_?1 H₂S resulted in an increase in sulfhydryl and sulfate content of 250 to 450% and 63 to 248% in the shoots, respectively, depending on growth temperature. Exposure to 0.15 and 0.30 μl l_?1 H₂S at 20°C for 2 weeks resulted in a 46% increase in sulfate content of the shoots at 0.30 μl l_?1 and no detectable increase at 0.15 μl l_?1 H₂S; the sulfate content of the roots increased by 195 and 145% at 0.15 and 0.30 μl l_?1 H₂S, respectively. Fumigation with 0.25 μl l_?1 SO₂ at 20°C for 2 weeks resulted in an increase in sulfhydryl content and sulfate content in the shoots of 285% and 300 to 1100%. H₂S fumigation during the 12 h light period or only during the dark period resulted in identical growth reduction and accumulation of sulfhydryl compounds; they were about 50 and 67% of those observed in continuously exposed plants. H₂S- and SO₂-exposed plants showed an increased transpiration rate, which was mainly caused by an increased dark-period transpiration. No effect of H₂S and SO₂ on the water uptake of the plants and the osmotic potential of the leaves was detected. Plants fumigated with 0.25 μl l_?1 H₂S for 2 weeks were smaller and differed morphologically from the control plants by slightly more abaxially curved leaf margins. Cross sections of the leaves showed smaller cells at the margins and smaller and fewer air spaces. The increased transpiration in the H₂S-exposed plants is discussed in relation to the observed morphological changes.     

The study of a French family with two duplicated C4A haplotypes

Summary The finding of two duplicated C4A haplotypes in a normal French family led to a detailed study of their C4 polymorphism. The father had an extremely rare A^*6A^*11, B^* QO haplotype inherited by all of his children and the mother had the more common A^*3A^*2, B^*QO haplotype. Two HLA identical daughters only have four C4A alleles. The father's A11 allotype expresses Ch: 1 (Chido) rather than Rg:1 (Rodgers) and represents a new Ch phenotype Ch: 1,-2,-3,-4,-5,-6. In order to clarify the genetic background in this unusual family, DNA studies of restriction fragment length polymorphisms (RFLPs) were undertake. The father's rare haplotype, which expresses two C4A allotypes, results from a long and a short C4 gene normally associated with the A^*6, B^*1 that also exhibits the BglII RFLP. As it travels in an extended MHC haplotype HLA A2, B57 (17), C2^*C, BF^*S, DR7 that is most frequently associated with A^*6, B^*1, we postulate that the short C4B has been converted in the chain region to a C4A gene which produces a C4A protein. This report of a short C4A gene is the first example in the complex polymorphism of C4.     

Complete maps of IS1, IS2, IS3, IS4, IS5, IS30 and IS150 locations in Escherichia coli K12

Summary In this paper complete distribution maps are presented of the seven IS elements 1, 2, 3, 4, 5, 30 and 150. These maps were obtained during the construction of an almost complete restriction map of the Escherichia coli genome of K12 strain BHB2600. The positions of IS elements were correlated to this map. The distribution of integration sites of all IS types is nonrandom. Besides a large gap from 79 min to 96 min, there is a pronounced IS cluster at 6 min and another at 97 min, map locations that have low gene incidences on the classical map. One cluster coincides with a region of IS induced rearrangements. The IS distribution pattern was compared to patterns of strains W3110 and HB101.     

Amyloplasts are necessary for full gravitropic sensitivity in roots of Arabidopsis thaliana

The observation that a starchless mutant (TC7) of Arabidopsis thaliana (L.) Heynh. is gravitropic (T. Caspar and B.G. Pickard, 1989, Planta 177, 185–197) raises questions about the hypothesis that starch and amyloplasts play a role in gravity perception. We compared the kinetics of gravitropism in this starchless mutant and the wild-type (WT). Wild-type roots are more responsive to gravity than TC7 roots as judged by several parameters: (1) Vertically grown TC7 roots were not as oriented with respect to the gravity vector as WT roots. (2) In the time course of curvature after gravistimulation, curvature in TC7 roots was delayed and reduced compared to WT roots. (3) TC7 roots curved less than WT roots following a single, short (induction) period of gravistimulation, and WT, but not TC7, roots curved in response to a 1-min period of horizontal exposure. (4) Wild-type roots curved much more than TC7 roots in response to intermittent stimulation (repeated short periods of horizontal exposure); WT roots curved in response to 10 s of stimulation or less, but TC7 roots required 2 min of stimulation to produce a curvature. The growth rates were equal for both genotypes. We conclude that WT roots are more sensitive to gravity than TC7 roots. Starch is not required for gravity perception in TC7 roots, but is necessary for full sensitivity; thus it is likely that amyloplasts function as statoliths in WT Arabidopsis roots. Furthermore, since centrifugation studies using low gravitational forces indicated that starchless plastids are relatively dense and are the most movable component in TC7 columella cells, the starchless plastids may also function as statoliths.Abbreviations S2 story two - S3 story three - WT wild-type     

Appearance of lectin-binding sites during vascularization of the primordium of the central nervous system in 10 to 12-day-old mouse embryos

Summary In the present study lectin-binding sites were investigated for the lectins Ricinus communis agglutinin (RCA I), wheat germ agglutinin (WGA), soya bean agglutinin (SBA), concanavalin A (Con A), Lotus tetragonolobus(LTA) and Limulus polyphemus agglutinin (LPA) during the initial stages of vasculogenesis of the CNS-anlage in 10 to 12-day-old NMRI mouse embryos. Specific binding sites for the lectins RCA I (sugar specificity: -D-galactose, N-acetylgalactosamine), WGA (sugar specificity: N-acetylglucosamine, sialic acid), and SBA (sugar specificity: N-acetylgalactosamine, -D-galactose) were detected in the newly formed capillaries within the neuroepithelial cell layer. In contrast, binding sites for Con A, LTA and LPA could not be observed at the start of the vascularization of the CNS-anlage. From these results, the conclusion can be drawn that glycoconjugates containing D-galactose, N-acetylgalactosamine and N-acetyl-glucosamine moieties are involved in the early vasculogenesis of the embryonic CNS-anlage of the mouse.     

Structure and composition of savanna vegetation in northern Bolivia: A preliminary report

The vegetation of seasonally flooded savannas iin the tropical lowland of the Departamento La Paz, northern Bolivia, was studied. A first collection of vascular plants in this area includes about 600 species, at least three of which are new to the Bolivian flora and four are new to science. The eight major vegetation types distinguished within the savannas are dry bunchgrass savanna (“altura”), seasonally flooded bunch-grass community (“sartenejal”), palm swamp (“palmar”), two types of river floodplains (”bajíos”), a tall shrub community (“chaparral”), the vegetation of termite mounds, and gallery forest. The study area is among the least known in Bolivia. There is a strong need for further studies of these savannas.