Bicyclonucleosides and ring-chain interconversion.

Four types of bicyclonucleosides differing in the easiness of their ring-chain interconversion have been prepared, some exhibited anti-HIV activity and the ratio of their cyclic and open-chain forms could have some bearing on their biological activity.     

Helicobacter pylori Infection in Congestive Gastropathy

Background. This study determines the prevalence and significance of Helicobacter pylori infection in portal hypertensive patients.
Materials and Methods. Patients numbered 118 and consisted of 90 patients with portal hypertension (66 men; 24 women; mean age, 49.1 ± 2.1 years) and 28 noncirrhotic patients with nonucler dyspepsia, (12 men; 16 women; mean age, 47.6 ± 2.8 years), who made up the control group. In all patients, diagnostic upper endoscopy was performed, and gastric biopsies were taken for histological examination and diagnosis of H. pylori.
Results. Of the portal hypertensive patients, 42 (47%) had congestive gastropathy, 11 (26%) of whom were positive for H. pylori. and 48 (53%) did not have gastropathy, 12 (25%) of whom were positive for H. pylori. In the control group, 15 of 28 (54%) were positive for H. pylori. H. Pylori was found less frequently in congestive gastropathy patients than in the control group. We found also that the presence and severity of congestive gastropathy is independent of H. pylori status.
Conclusions. We conclude that the role of H. pylori in the pathogenesis of congestive gastropathy is unlikely, and we suggest that there is no need for its routine eradication in cirrhotic patients.     

The nectary as the primary site of infection by Erwinia amylovora (Burr.) Winslow et al.: a mini review

 Erwinia amylovora is the causative agent of fire blight, a bacterial disease existing as an unsolved problem in most countries where pome fruits like apple (Malus domestica) and pear (Pyrus communis) or ornamental plants of Rosaceae are grown. The primary site of colonization is the open flower. As for the establishment of the disease, the importance of various organs within the flowers is considerably different. The usual place for developing a large epiphytic population is the stigma. The actual infection will be attained by the external washing (rain, heavy dew) of bacteria from the stigma to the hypanthium. The bacteria penetrate through the openings of the nectary, so, the nectarthodes are the main entrance sites for them. Nectar is an excellent medium for growth of fire blight bacteria. Most often, however, the incidence of disease is significantly less than the percentage of colonized flowers. Little is known about the interrelationships of free moisture, nectar sugar concentration, ovary water potential, fine-structural characteristics of nectary versus the disease incidence and severity. The aim of this paper is to review the ecology and infection biology of Erwinia amylovora on floral surfaces and in floral tissues. Received July 8, 2002; accepted October 17, 2002 Published online: June 2, 2003     

Longhorn beetles and predatory clerid beetles attracted to a blend of longhorn beetle pheromone compounds in a Central European oak forest (Coleoptera: Cerambycidae,Cleridae)

1. A blend of longhorn beetle pheromones was tested as a generic attractant in a Central European oak forest. Overall, 20 cerambycid species totalling 1250 specimens were captured using two trap types.
2. More adults of Phymatodes testaceus and Leiopus nebulosus nebulosus were attracted to pheromone-baited traps compared to solvent controls. Significant numbers of four other species were caught by panel traps but not funnel traps. For the cerambycine Pyrrhidium sanguineum, significantly more beetles were caught in treatment traps than controls. For the cerambycine Anaglyptus mysticus, lepturines Cortodera humeralis and Rhagium sycophanta, the numbers of beetles caught in treatment or control traps were similar, indicating no attraction to the lure blend. Adults of a predatory clerid beetle Clerus mutillarius were caught in significantly larger numbers by both baited trap types in comparison to controls, totalling 1514 specimens.
3. Antennae of both sexes of C. mutillarius showed responses to 3-hydroxyhexan-2-one and 2-methylbutan-1-ol, and males also responded to syn-2,3-hexanediol.
4. Strong attraction of C. mutillarius suggests eavesdropping on the pheromones of cerambycids and that such attractant baits, without traps, might be used to manipulate the local population density of predators in a push-pull biological control program.

     

Environmental constraint of intraguild predation: Inorganic turbidity modulates omnivory in fairy shrimps

1. Omnivory is widespread in food webs, with an important stabilising effect. The strength of omnivorous trophic interactions may change considerably with changes in the local environment.
2. Shallow temporary waters are often characterised by high levels of inorganic turbidity that may directly limit the food uptake of filter-feeding organisms, but there is little evidence on how it might affect omnivorous species. Anostracans are key species of temporary waters and recent evidence suggests that these organisms are omnivorous consumers of both phyto- and zooplankton.
3. Using Branchinecta orientalis as a model species, our aim was to test how turbidity affects the feeding of an omnivorous anostracan. To do this, we used short-term feeding experiments and stable isotope analyses, with animals collected from soda pans in eastern Austria. In the feeding experiments, algae and zooplankton were offered as food either separately or in combination. The prey type treatments were crossed with turbidity levels in a factorial design.
4. There was a pronounced decrease in the ingested algal biomass with increasing turbidity. Conversely, ingestion rates on zooplankton were less affected by turbidity. Stable isotope analyses from field material supported our experimental results by showing a positive relationship of the trophic position of anostracans and the trophic niche of the communities with turbidity.
5. Our results show that turbidity modulates the intraguild trophic relationship between anostracans and their prey by shifting the diet of anostracans from more herbivorous in transparent to more carnivorous in turbid waters. Thus, inorganic turbidity might also have a community-shaping role in plankton communities of temporary waters through altering trophic relationships.