Distribution and Efficiency of Bacteriolysis in the Gut of Arenicola Marina and Three Additional Deposit Feeders

A simple technique was developed to measure the bacteriolytic activities of the digestive fluids of the deposit-feeding polychaete Arenicola marina. Lysis of a cultured environmental isolate, incubated with extracts of gut luminal contents, was monitored spectrophotometrically. Concurrent direct counts were used to verify cell lysis. The ability of extracts from 8 longitudinal sections of the gut to lyse the bacterium was monitored. The digestive ceca, anterior stomach, and posterior stomach regions exhibited high lytic activities, whereas bacteriolytic activities in all other regions of the gut were negligible. Similarly, extracts of surface sediments and fecal castings showed negligible lytic capabilities. The sharply limited distribution of lytic activity implicates the ceca as the source of bacteriolytic agent and suggests a true plug-flow system, with little axial mixing. Questions regarding the fate of lytic agents, which disappear abruptly posterior to the stomach, remain unanswered. Localization of lysis in the gut coupled with estimates of gut residence time permit the calculation that ingested bacteria are exposed to strong lytic activity for approximately 20 min. Incubation of in situ sediment samples with gut fluids corroborates the distributional findings of the in vitro work although the efficiency of lysis is much reduced, possibly due to exopolymer capsules and slimes of natural sedimentary bacteria. Cross-phyletic comparisons of bacteriolytic activities reveal both qualitative and quantitative differences. Much less demarcation of lytic activity is observed in the guts of a holothuroid (Caudina arenata) and a hemichordate (Stereobalanus canadensis), with a pattern more similar to that of A. marina observed in another polychaete, Amphitrite johnstoni. Quantitatively, the polychaetes showed higher levels of activity with rates in A. marina exceeding those of the hemichordate and holothuroid by more than 10-fold.

Structures and Concentrations of Surfactants in Gut Fluid of the Marine Polychaete Arenicola Marina

Marine invertebrate deposit feeders secrete surfactants into their gut fluid in concentrations sufficient to induce micelle formation, enhancing solubilization of sedimentary lipids. We isolated and identified 3 related surfactant molecules from the deposit-feeding polychaete lugworm Arenicola marina. Surfactants were isolated and separated by a combination of solvent extraction and thin-layer and gas chromatography. Identification was performed using mass and infrared spectrometry, coupled to various derivatization and hydrolysis reactions. A. marina produces a mixture of related yet distinct anionic surfactants composed of branched, C9, saturated and unsaturated fatty acids that are amide linked to leucine or glycine residues, showing some similarity to crustacean surfactants. The critical micelle concentration of the mixture of these surfactants in gut fluid was about 2 mM, and total concentrations ranged from 5.5 to 19.5 mM. The hydrophilic amide linkage helps to explain previous observations that gut surfactants do not adsorb onto sediment transiting the gut.

A review on bovine besnoitiosis: a disease with economic impact in herd health management, caused by Besnoitia besnoiti (Franco and Borges, 1916).

Bovine besnoitiosis is caused by the largely unexplored apicomplexan parasite Besnoitia besnoiti. In cows, infection during pregnancy often results in abortion, and chronically infected bulls become infertile. Similar to other apicomplexans B. besnoiti has acquired a largely intracellular lifestyle, but its complete life cycle is still unknown, modes of transmission have not been entirely resolved and the definitive host has not been identified. Outbreaks of bovine besnoitiosis in cattle were described in the 1990s in Portugal and Spain, and later several cases were also detected in France. More cases have been reported recently in hitherto unaffected countries, including Italy, Germany, Switzerland, Hungary and Croatia. To date, there is still no effective pharmaceutical compound available for the treatment of besnoitiosis in cattle, and progress in the identification of novel targets for intervention through pharmacological or immunological means is hampered by the lack of molecular data on the genomic and transcriptomic level. In addition, the lack of an appropriate small animal laboratory model, and wide gaps in our knowledge on the host-parasite interplay during the life cycle of this parasite, renders vaccine and drug development a cost- and labour-intensive undertaking.

Discorso inaugurale per la nuova sede dell' accademia religiosa "Joseph Franco" 15 Adar 5669 - 8 Marzo 1909

[von] Samuele Colombo

Une solidarité franco-allemande en Suisse au coeur de la première guerre : Stefan Zweig (1881-1942) et Romain Rolland (1866-1944)

Stefan Zweig arrive en Suisse en novembre 1917. D’abord libéré du service militaire pour deux mois, il obtient finalement la permission de rester en Suisse jusqu’à la fin de la guerre. Il peut ainsi assister aux répétitions et à la première de Jérémie, sa pièce de théâtre pacifiste représentée pour la première fois au Stadttheater de Zurich en février 1918. Son séjour en Suisse est également marqué par le développement de son admiration et de son amitié pour Romain Rolland – celui qu’il désigne comme étant « la conscience morale de l’Europe ». L’objet de cet article est de montrer que la conjonction Suisse–Rolland a joué un rôle absolument essentiel dans la vie personnelle et créatrice de Zweig.

Seasonal Variability in the Bacteriolytic Capacity of the Deposit Feeder Arenicola Marina: Environmental Correlates

Although deposit-feeding macrofauna consume and digest sedimentary bacteria, it is unclear whether feeding rates and digestion efficiencies are high enough to significantly impact the composition and abundance of bacteria in marine sediments. It is likely that both feeding rates and efficiency of digestion vary markedly through space and time. We used a turbidimetric assay to compare the rate of bacteriolysis by digestive fluids collected seasonally from the deposit-feeding polychaete Arenicola marina. Under standardized, experimental conditions, bacteriolytic rates represent concentrations of lytic agents. This concentration was found to vary significantly throughout the year (p = 0.001), showing greater than a 2x range. Lytic agent concentration was positively correlated with bioavailable amino acid concentrations in the surface sediment (r = 0.85, p = 0.03) but showed no apparent relationship to other proxies for food resources (e.g, chl a), sediment temperature, or gut throughput time. In vitro, temperature has been shown to have a strong positive influence on bacteriolytic rate. Temperature has no influence, however, on the in situ concentration of lytic agent in gut fluids, thus it appears that compensation for this temperature dependence is unimportant. These findings, combined with previous kinetics studies with A. marina gut fluids, predict that the quantitative influence of deposit feeding on the microbial ecology of sediments will exhibit clear seasonal variation.

Freedom Fries or Friendship Fries? : Franco-American Stereotypes and Meta-Stereotypes

This study explores Franco-American relations by examining Franco-American stereotypes. When American participants made ratings of what they think the French think of Americans, the results showed that Americans think the French see Americans in a very negative light. Yet, when the French participants rated what they think Americans think of the French, the result was fairly neutral. Both the French and Americans were found to be over-estimating how negatively they are actually viewed by the other group. If Americans think the French view them negatively and vice versa, these beliefs can permeate interpersonal interactions and can have a potentially negative effect. The results suggest that stereotypes play an important role in intergroup interactions and these findings have important implications for Franco-American relations.

Difesa della Musica moderna contro la falsa opinione del Vescovo Cirillo Franco

[Verf.: Johann IV, König von Portugal]

Franco Sacchetti, Brustbild

Signatur des Originals: S 36/G02104

Franco Sacchetti, Brustbild, Profil

Signatur des Originals: S 36/G02105

Franco Sacchetti, Brustbild

Signatur des Originals: S 36/G02106

Franco Sacchetti, Brustbild, Profil

Signatur des Originals: S 36/G02107

Franco Sacchetti, Brustbild, Profil

Signatur des Originals: S 36/G02108