PHYLOGENETIC RELATIONSHIPS AMONG PAPER WASP SOCIAL PARASITES AND THEIR HOSTS (HYMENOPTERA: VESPIDAE; POLISTINAE)

Abstract— Cladistic analyses of data from allozyme polymorphisms in paper wasp social parasites and their hosts do not support the hypothesis that social parasites are most closely related to their hosts. Electrophoretic data are adduced for nine species of Polistes , including all three known species of social parasites ( Sulcopolistes ) and their hosts. Three different coding methods are investigated; in no case do the social parasites cluster most closely with their hosts. Rather, there is limited evidence that they form a monophyletic group. However, formal taxonomic recognition of Sulcopolistes is not justified, as it renders Polistes sensu stricto paraphyletic. Although the social parasites are not most closely related to their hosts, hosts and parasites belong in the same subgenus and share many characteristics that may have facilitated the exploitation and deception practised by the parasites on the hosts.     

Somatic embryo and root regeneration from quince leaves cultured in ventilated vessels or under different oxygen and carbon dioxide levels

Summary The influence of the gaseous composition of the atmosphere inside culturing vessels on somatic embryogenesis and on adventitious root formation was investigated in the quince clone (Cydonia ablonga Mill.) BA29. Leaves taken from in vitro-grown shoots were cultured in glass Petri dishes and exposed to ventilation with atmospheric air (flow rate 25 ml min⁻¹) for 0, 5, 10, 20, and 40 d. Twenty days of ventilation reduced the frequency of embryogenic leaves and a further decrease was observed after 40d of treatment. Conversely, adventitious root formation in the ventilated dishes was never different from the untreated cultures. In a second test, leaves were incubated in atmospheres containing different levels of oxygen (0, 5.0, 10.0, and 21.0%) or carbon dioxide (0, 0.04, 0.15, 1.5, and 3.0%). Anoxia conditions almost completely inhibited somatic embryo and adventitious root formation, but without compromising callus formation and explant viability. In contrast, embryo and root regeneration occurred even in totally CO₂-free atmosphere. Oxygen seemed to influence somatic embryogenesis according to a quadratic response; a similar relationship was also observed for root regeneration. Instead, no clear trend could be inferred between embryo or root regeneration and CO₂ levels. Furthermore, in dishes flushed with gas mixtures containing oxygen or carbon dioxide somatic embryo formation was almost always lower than in confined dishes. A different result was observed for root regeneration, since the number of roots was never lower than in the control and increased appreciably with 3.0% CO₂. These results demonstrate that atmosphere composition of the culture head-space can influence somatic embryogenesis in quince. The finding that both vessel ventilation and atmosphere replacement with different gas mixtures reduced somatic embryo formation suggests that gaseous compounds, different from O₂ an CO₂, present in the gaseous environment may promote embryogenesis in this species.     

Small hydroxyethylene-based peptidomimetics inhibiting both HIV-1 and C. albicans aspartic proteases

We have extended a highly flexible method for rapidly assembling aspartic protease inhibitors to produce symmetric and asymmetric monohydroxyethylene peptidomimetics. This method is based on the prior synthesis of the central non-cleavable peptide-bond isostere [NH(2)-P(1)psiP1'-NH(2); psi=hydroxyethylene isostere, HNCH(Bz)CHOHCH(2)CH(Bz)NH], with the possibility of accurately controlling its stereochemistry (S,S,S or S,R,S), and subsequently adding appropriate flanking units, chosen from commercially available amino acids, aromatic carboxylic acids, or phenoxyacetic acid (Poa) derivatives. The method was used to make asymmetric inhibitors of general formula Kyn-Xaa-PhepsiPhe-dmPoa, (Kyn=kynurenic acid, Xaa=Val, Thr or D-thienylglycine, M(r)=716-754) and symmetric inhibitors of formula xPoa-PhepsiPhe-xPoa (xPoa=Poa or dimethyl-, hydroxy-, formyl- or acetyl-Poa, M(r)=553-609), with logP(o/w) values ranging from 4.1 to 7.6. Inhibition of HIV-PR did not depend on the stereochemistry of the hydroxyl group, while it depended markedly on the substituents present on the Poa residues, with dmPoa being preferred over Poa or its more hydrophilic derivatives. Conversely, inhibition of Candida albicans Sap2 was higher for the S,S,S epimers, and Poa or its hydrophilic derivatives were preferred over dmPoa.     

Interaction between gfp-tagged Pseudomonas tolaasii P12 and Pleurotus eryngii

Pseudomonas sp., (formerly reported as strain P12) which produces brown blotch disease symptoms on Pleurotus eryngii, has been identified as P. tolaasii based on its biochemical, physiological properties and 16S rDNA sequence analysis. This pathogen is able to infect basidiocarps when surface-inoculated on mushroom casing soil. However, infected basidiocarps develop the brown blotch disease symptoms when the pathogen concentration in the fruiting body tissues is higher than 10(4) cfu/g d.w. Using gfp-tagged cells and confocal laser scanning microscopy, it was possible to show that the pathogen has the ability to tightly attach to the hyphae of Pleurotus eryngii.     

Characterization of the major allergens purified from the venom of the paper wasp Polistes gallicus

Allergic reactions to vespid stings are one of the major causes of IgE-mediated anaphylaxis. Vespa and Vespula venoms are closely related; Polistes venom is more distantly related and its allergens are less well studied. There is limited cross-reactivity between Polistes and the other vespid venoms because of differences in the epitopes on the allergen molecules.In this study, the major allergens of Polistes gallicus are isolated and characterized. P. gallicus venom contains four major allergens: phospholipase, antigen 5 (Ag5), hyaluronidase and protease that were characterized by mass spectrometry and specific binding to IgE. The complete amino acid sequence of Ag5 and the sequence of the N-terminal region of phospholipase were also determined. The alignment of Ag5 from P. gallicus (European species) and Polistes annularis (American species) shows an 85% identity that increases to 98% within the same subgenus. This could suggest the presence of specific epitopes on Ag5 molecule being the variations on the superficial loops. The features of the P. gallicus allergens could explain the partial cross-reactivity found between the American and European Polistes venoms, and suggest that the use of European Polistes venoms would improve the diagnostic specificity and the therapy of European patients and of North American patients sensitized by European Polistes.     

Role of chirality and optical purity in nucleic acid recognition by PNA and PNA analogs

Peptide nucleic acids are DNA mimics able to form duplexes with complementary DNA or RNA strands of remarkable affinity and selectivity. Oligopyrimidine PNA can displace one strand of dsDNA by forming PNA(2):DNA triplexes of very high stability. Many PNA analogs have been described in recent years, in particular, chiral PNA analogs. In the present article the results obtained recently using PNA derived from N-aminoethylamino acids 7 are illustrated. In particular, the dependence of optical purity on synthetic methodologies and a rationale for the observed effects of chirality on DNA binding ability is proposed. Chirality as a tool for improving sequence selectivity is also described. PNA analogs derived from D- or L-ornithine 8 were also found to be subjected to epimerization during solid phase synthesis. Modification of the coupling conditions or the use of a submonomeric strategy greatly reduced epimerization. The optically pure oligothymine PNAs 8 were found to bind to RNA by forming triplexes of unusual CD spectra. The melting curves of these adducts presented two transitions, suggesting a conformational change followed by melting at high temperature.     

The expression of the dodecameric ferritin in Listeria spp. is induced by iron limitation and stationary growth phase

The new discipline of Evolutionary Developmental Biology (Evo-Devo) is facing the fascinating paradox of explaining morphological evolution using conserved pieces or genes to build divergent animals. The cephalochordate amphioxus is the closest living relative to the vertebrates, with a simple, chordate body plan, and a genome directly descended from the ancestor prior to the genome-wide duplications that occurred close to the origin of vertebrates. Amphioxus morphology may have remained relatively invariant since the divergence from the vertebrate lineage, but the amphioxus genome has not escaped evolution. We report the isolation of a second Emx gene (AmphiEmxB) arising from an independent duplication in the amphioxus genome. We also argue that a tandem duplication probably occurred in the Posterior part of the Hox cluster in amphioxus, giving rise to AmphiHox14, and discuss the structure of the chordate and vertebrate ancestral clusters. Also, a tandem duplication of Evx in the amphioxus lineage produced a prototypical Evx gene (AmphiEvxA) and a divergent gene (AmphiEvxB), no longer involved in typical Evx functions. These examples of specific gene duplications in amphioxus, and other previously reported duplications summarized here, emphasize the fact that amphioxus is not the ancestor of the vertebrates but 'only' the closest living relative to the ancestor, with a mix of prototypical and amphioxus-specific features in its genome.     

Influence of Initial Population Densities of Meloidogyne incognita on Three Chile Cultivars

The effects of Meloidogyne incognita on the Big Jim, Jalapeno, and New Mexico No. 6 chile (Capsicum annuum) cultivars were investigated in microplots for two growing seasons. All three cultivars were susceptible to M. incognita and reacted similarly to different initial populations of this nematode. Severe stunting and yield suppressions occurred at all initial M. incognita densities tested ranging from 385 to 4,230 eggs and larvae/500 cm³ soil. Regression analysis of the microplot data from a sandy loam soil showed yield losses of 31% for the 1978 season and 25% for the 1979 season for the three cultivars for each 10-fold increase in the initial population of M. incognita.