Über zwei verschiedene Nervenfasertypen im Hornhautstroma des Kaninchenauges

Zusammenfassung Mit der panoptischen Silberkarbonatmethode del Rio Hortegas gelang es, im Hornhautstroma des Kaninchenauges zwei nach Kaliber, Verlaufsart, Verzweigungstypus und Endigungsweise eindeutig verschiedene Nervenfasertypen darszustellen.Mit der Unterstützung des U.S. Department of Public Health and Welfare.     

Increased gonad ratio in the blue mussel, Mytilus edulis, exposed to starfish predators

The presence of invertebrate predators can induce morphological, physiological, and behavioural changes in sessile marine prey species. In this study, I investigated whether the risk of predation can alter the reproductive effort in the blue mussel Mytilus edulis. In the field, I cultured blue mussels in the presence and in the absence of the starfish, Asterias rubens, using enclosures with two compartments. Two experiments were performed with field periods of 19 and 30 days, respectively. After the field exposure, the mussels were examined for weight of flesh and gonad tissue. In both experiments, the starfish-exposed mussels developed a significantly larger gonad to flesh ratio, compared with that of the unexposed control mussels. After 30 days, the exposed mussels had also lost flesh weight significantly, probably due to spawning. These changes suggest that M. edulis accelerates the gonad development and/or increases its reproductive effort in the presence of predators. Predator-inducible adjustment of life-history characters should be a beneficial trait for this sessile species, that typically encounters a high and variable predation pressure. This revised version was published online in August 2006 with corrections to the Cover Date.     

A kindred with 5 cases of multiple endocrine adenomatosis type I

Details of health, with particular reference to endocrinopathy, were acquired on all living and decreased members of a 4 generation family. Five members were found to be affected with MEA-I. Hyperparthyroidism was the most frequently diagnosed endocrinopathy, but pancreatic tumors were also found to be involved. No indications of the involvement of pituitary tumors were observed. A mediastinal tumor accompanied by a thymoma was also observed. None of the children under 18 years of age were affected. Genetic analysis confirmed the concept that the syndrome follows an autosomal dominant mode of inheritance with virtually complete penetrance but variable expressivity. A careful investigation at regular intervals of high risk members of an affected family is recommended for proper medical management of the condition.     

Strategy maps: Generalised giving-up densities for optimal foraging

Finding a common currency for benefits and hazards is a major challenge in optimal foraging theory, often requiring complex computational methods. We present a new analytic approach that builds on the Marginal Value Theorem and giving-up densities while incorporating the nonlinear effect of predation risk. We map the space of all possible environments into strategy regions, each corresponding to a discrete optimal strategy. This provides a generalised quantitative measure of the trade-off between foraging rewards and hazards. This extends a classic optimal diet choice rule-of-thumb to incorporate the hazard of waiting for better resources to appear. We compare the dynamics of optimal decision-making for three foraging life-history strategies: One in which fitness accrues instantly, and two with delays before fitness benefit is accrued. Foragers with delayed-benefit strategies are more sensitive to predation risk than resource quality, as they stand to lose more fitness from a predation event than instant-accrual foragers.     

Mosquito-Parasite Interactions Can Shape Filariasis Transmission Dynamics and Impact Elimination Programs

The relationship between mosquito vectors and lymphatic filariasis (LF) parasites can result in a range of transmission outcomes. Anophelines are generally characterized as poor vectors due to an inability to support development at low densities. However, it is important to understand the potential for transmission in natural vectors to maximize the success of elimination efforts. Primary vectors in Papua New Guinea (n = 1209) were dissected following exposure to microfilaremic blood (range 8–233 mf/20 µl). We examined density dependent and species-specific parasite prevalence, intensity and yield, barriers to parasite development as well as impacts on mosquito survival. We observed strikingly different parasite prevalence and yield among closely related species. Prevalence of infective stage larvae (L3s) ranged from 4.2% to 23.7% in An. punctulatus, 24.5% to 68.6% in An. farauti s.s. and 61.9% to 100% in An. hinesorum at low and high density exposures, respectively. Injection experiments revealed the greatest barrier to parasite development involved passage from the midgut into the hemocoel. The ratio of L3 to ingested mf at low densities was higher in An. hinesorum (yield = 1.0) and An. farauti s.s. (yield = 0.5) than has been reported in other anopheline vectors. There was a negative relationship between mosquito survival and bloodmeal mf density. In An. farauti s.s., increased parasite yield and survival at low densities suggest greater competence at low microfilaremias. In Papua New Guinea the likelihood of transmission will be strongly influenced by vector composition and changes in the mf reservoir as a result of elimination efforts. Global elimination efforts will be strengthened by the knowledge of transmission potential in the context of current control measures.     

Effects of crude oil on the feeding behaviour of the zoanthid Palythoa variabilis.

Palythoa variabilis (Duerden 1898) has a well-coordinated, sterotyped feeding response similar to that described for other zoanthids. The feeding reaction can be elicited by the heterocyclic amino acid proline and by some of its analogs. The addition of an OH group (hydroxyproline) or of a glycyl group (prolylglycine) annuls the activity of the proline molecule. Substitutions (thiazolidine-4-carboxylic acid) or additions (glycylproline) to the amino group do not alter the effectivity of the activator. The size of the ring can be altered within certain limits (azetidine-2-carbocylic acid and pipecolic acid) without affecting the activity of the molecule. Feeding reactions culminating with ingestion can be elicited by Marine Diesel and Bunker-C oils. Exposure to oil affects the ability of polyps to discriminate between inert and chemically active particles for 3 to 5 days; responses to proline are not altered for at least 3 days following the exposure, but become slower and are present in fewer polyps after that period. Oil is retained in the coelenteron for several days following exposure and is periodically released in the form of timy droplets.