Letter from Howard E. Hugo to Hubert Creekmore

Hugo writes from Harvard University in Cambridge, Massachusetts, to Creekmore about the anthology Creekmore is compiling and translating.https://egrove.olemiss.edu/creekmore/1067/thumbnail.jp

Variation et évolution de la composition du venin des guêpes parasitoïdes Psyttalia (Hymenoptera, Braconidae) et Leptopilina (Hymenoptera, Figitidae) : une cause possible d'échec et de succès en lutte biologique ?

Endoparasitoid wasps lay eggs and develop inside arthropod hosts, leading to their death. They have evolved various strategies to ensure parasitism success, notably the injection with the eggs of venom that suppresses the host immunity. Although venom composition has been characterized in a growing number of parasitoid families and recent studies suggest that parasitoid virulence can rapidly evolve, the intraspecific variation of venom and its short-Term evolvability remained to be investigated. This information is however essential for understanding the evolution of parasitoid host range and may have implications in biological control. This thesis allowed to demonstrate the occurrence of inter-Individual variability of venom and to develop a method based on the analysis of electrophoretic 1D profiles and the use of “R” functions allowing statistic comparison of protein quantities from numerous individuals. Then, to study the effect of this variability of the venom composition, experimental evolution studies were performed on Psyttalia lounsburyi and Leptopilina boulardi. Overall, the thesis evidenced that parasitoid venom composition (i) is variable at all studied biological levels (ii) changes rapidly, confirming its high evolvability, and (iii) influences key parameters of the parasitoid biology. This may have important implications in biocontrol and raises the question of the mechanisms sustaining this variability.Les guêpes endoparasitoïdes effectuent leur développement dans un hôte arthropode, entraînant sa mort. Parmi les stratégies assurant leur succès parasitaire, la plus commune est l’injection de venin dans l’hôte lors de l’oviposition, provoquant la suppression de l’immunité de l’hôte. Il est connu que la composition du venin est variable entre espèces et que la virulence des parasitoïdes peut évoluer rapidement. Pourtant la variation intraspécifique de la composition du venin n’a jamais été étudiée alors qu’elle est essentielle pour comprendre l’évolution de la gamme d’hôte des parasitoïdes, un paramètre clé en lutte biologique. Cette thèse a permis de démontrer l’existence d’une variabilité inter-Individuelle du venin, et de développer une méthode basée sur l’analyse de profiles d’électrophorèse 1D à l’aide de fonctions “R” permettant la comparaison statistique de la composition protéique d’un grand nombre d’individus. Des évolutions expérimentales ont ensuite été réalisée sur Psyttalia lounsburyi et Leptopilina boulardi pour étudier les effets de la variabilité du venin lors d’un changement d’environnement brutal. Globalement, cette thèse a mis en évidence que la composition du venin (i) est très variable à tous les niveaux étudiés, (ii) évolue rapidement et (iii) impacte des paramètres clés de la biologie des parasitoïdes. Ceci pourrait avoir d’importantes implications en lutte biologique et pose la question des mécanismes de maintien de la variabilité du venin dans le milieu naturel

A PCR-based method for estimating parasitism rates in the olive fly parasitoids Psyttalia concolor and P. lounsburyi (Hymenoptera: Braconidae)

International audienceSeveral parasitoids of the genus Psyttalia have been repeatedly introduced as biological control agents against the principal pest of olive, the fly Bactrocera oleae. However, few of the parasitoids released have become established and proved effective against B. oleae. It may however still be possible to find effective biological control agents adapted to local environmental conditions among the highly diverse Psyttalia species and populations infesting B. oleae worldwide. For this purpose, we have developed a rapid, sensitive molecular method based on the polymerase chain reaction (PCR) for estimating and comparing the parasitism success of Psyttalia parasitoids through the detection of eggs and larvae within the host. This method was tested and shown to be appropriate for two Psyttalia species (Psyttalia concolor and Psyttalia lounsburyi). The possible detection of DNA was also demonstrated for several populations of these species and for other Psyttalia species, namely Psyttalia humilis and Psyttalia ponerophaga. For P. concolor and P. lounsburyi, a strong correlation was observed between the parasitism rates estimated by PCR, host larva dissection and counts of emerging parasitoids. No significant difference was found between the rates of parasitism estimated by host larva dissection and PCR, whereas the rates of parasitism estimated by PCR were significantly higher than those estimated from emergence, suggesting occurrence of mortality during the parasitoid development. This PCR method is thus highly reliable and provides an objective criterion for estimating the efficacy of biological control agent candidates from diverse taxa and populations of Psyttalia. ⇑ Corresponding author

Contribution of the microvessel network to the clonal and kinetic profiles of adrenal cortical proliferative lesions

Monoclonal adrenocortical lesions have been characterized by an inverse correlation between proliferation and apoptosis, and polyclonal lesions show a direct correlation. Their relationship with the vascular pattern remains unknown in adrenocortical nodular hyperplasias (ACNHs), adenomas (ACAs), and carcinomas (ACCs). We studied 20 ACNHs, 25 ACAs, and 10 ACCs (World Health Organization classification criteria) from 55 women. The analysis included X-chromosome inactivation assay (on microdissected samples), slide and flow cytometry, and in situ end labeling. Endothelial cells were stained with anti-CD31, and the blood vessel area and density were quantified by image analysis in the same areas. Appropriate tissue controls were run in every case. Regression analyses between kinetic and vascular features were performed in both polyclonal and monoclonal lesions. Polyclonal patterns were observed in 14 of 18 informative ACNHs and 3 of 22 informative ACAs, and monoclonal patterns were seen in 4 of 18 ACNHs, 19 of 22 ACAs, and 9 of 9 ACCs. A progressive increase in microvessel area was observed in the ACNH–ACA–ACC transition but was statistically significant between benign and malignant lesions only (191.36 ± 168.32 v 958.07 ± 1279.86 μm2; P 186 μm2 (P =.0000008). Monoclonal lesions showed parallel trends (but with opposite signs) for microvessel area and density in comparison with proliferation and apoptosis, whereas polyclonal lesions showed inverse trends. In conclusion, the kinetic advantage of monoclonal adrenal cortical lesions (increased proliferation, decreased apoptosis) is maintained by parallel increases in microvessel area and density. HUM PATHOL 32:1232-1239. Copyright © 2001 by W.B. Saunders Compan

Reflecting on factors influencing long-lasting organisational effects of group model-building interventions

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Clonal patterns in phaeochromocytomas and MEN-2A adrenal medullary hyperplasias: histological and kinetic correlates

The relationship among histological features, cell kinetics, and clonality has not been studied in adrenal medullary hyperplasias (AMHs) and phaeochromocytomas (PCCs). Thirty-four PCCs (23 sporadic and 11 MEN-2A (multiple endocrine neoplasia type 2A)-related tumours, the latter associated with AMH) from females were included in this study. Representative samples were histologically evaluated and microdissected to extract DNA and evaluate the methylation pattern of the androgen receptor alleles. At least two tissue samples (from the peripheral and internal zones in each tumour) were analysed with appropriate tissue controls run in every case. The same areas were selected for MIB-1 staining and in situ end labelling (ISEL). Malignant PCCs were defined by histologically confirmed distant metastases. All monoclonal AMH nodules from the same patient showed the same X-chromosome inactivated. Six sporadic PCCs revealed liver metastases (malignant PCC) and eight additional sporadic PCCs showed periadrenal infiltration (locally invasive PCC). All informative PCCs were monoclonal, except for five locally invasive PCCs and one benign PCC that revealed polyclonal patterns. Those cases also showed a fibroblastic stromal reaction with prominent blood vessels, focal smooth muscle differentiation, and significantly higher MIB-1 (126.8±29.9) and ISEL (50.9±12.8) indices. Concordant X-chromosome inactivation in nodules from a given patient suggests that MEN-2A AMH is a multifocal monoclonal condition. A subgroup of PCCs characterized by balanced methylation of androgen receptor alleles, high cellular turnover, and stromal proliferation also shows locally invasive features. Copyright © 2000 John Wiley & Sons, Ltd

Reflecting on factors influencing long-lasting organisational effects of group model-building interventions

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Rapid and dfferential evolution of the venom composition of a parasitoid wasp depending on the host strain

Abstract: Parasitoid wasps rely primarily on venom to suppress the immune response and regulatethe physiology of their host. Intraspecific variability of venom protein composition has beendocumented in some species, but its evolutionary potential is poorly understood. We performed anexperimental evolution initiated with the crosses of two lines of Leptopilina boulardi of differentvenom composition to generate variability and create new combinations of venom factors. Theoffspring were maintained for 10 generations on two strains of Drosophila melanogaster differing inresistance/susceptibility to the parental parasitoid lines. The venom composition of individuals wascharacterized by a semi-automatic analysis of 1D SDS-PAGE electrophoresis protein profiles whoseaccuracy was checked by Western blot analysis of well-characterized venom proteins. Results madeevident a rapid and differential evolution of the venom composition on both hosts and showed thatthe proteins beneficial on one host can be costly on the other. Overall, we demonstrated the capacityof rapid evolution of the venom composition in parasitoid wasps, important regulators of arthropodpopulations, suggesting a potential for adaptation to new hosts. Our approach also proved relevantin identifying, among the diversity of venom proteins, those possibly involved in parasitism successand whose role deserves to be deepened

Variability of venom components in immune suppressive parasitoid wasps: From a phylogenetic to a population approach

International audienceEndoparasitoid wasps develop at the expense of other insects, leading to their death. Eggs deposited inside the host body induce an immune response, which results in the formation of a melanized cellular capsule around the egg. To evade or counteract this response, endoparasitoids have evolved different strategies, the most often reported being injection into the host of immunosuppressive factors, notably venom proteins, along with the egg. The analysis of venom components has been performed independently in species of different taxa, but the present picture is far from complete. Intriguingly, the question of the level of venom variability inside species has been neglected, although it may partly determine the potential for parasitoid adaptation. Here, we present a short review of our present knowledge of venom components in endoparasitoids, as well as of the only well-known example of intraspecific variability in a venom immune suppressive protein being responsible for variation in parasitoid virulence. We then present data evidencing inter-individual variation of venom protein profiles, using a gel electrophoresis approach, both in laboratory strains and field populations of a figitid and a braconid species. Whether occurrence of such variability may permit a selection of parasitoid venom components driven by the host remains to be tested, notably in the context of the production and use of biological control auxiliaries