Linking the evolution of habitat choice to ecosystem functioning: direct and indirect effects of pond-reproducing fire salamanders on aquatic-terrestrial subsidies

Shifts in life history traits and in the behaviour of species can potentially alter ecosystem functioning. The reproduction of the central European fire salamander (Salamandra salamandra), which usually deposits its larvae in first-order streams, in small pool and pond-like habitats, is an example of a recent local adaptation in this species. Here we aimed to quantify the direct and indirect effects of the predatory larvae on the aquatic food webs in the ponds and on the flux of matter between the ponds and adjacent terrestrial habitats. Our estimates are based on biomass data of the present pond fauna as well as on the analysis of stomach content data, growth rates and population dynamics of the salamander larvae in pond habitats. By their deposition of larvae in early spring, female fire salamanders import between 0.07 and 2.86 g dry mass m^?2 larval biomass into the ponds. Due to high mortality rates in the larval phase and the relatively small size at metamorphosis of the pond-adapted salamanders compared to stream-adapted ones, the biomass export of the metamorphosed salamanders clearly falls below the initial biomass import. Catastrophic events such as high water temperatures and low oxygen levels may even occasionally result in mass mortalities of salamander larvae and thus in a net 100 % import of the salamander biomass into the pond food webs. Indirect effects further accelerate this net import of matter into the aquatic habitat, e.g. the feeding of salamanders on aquatic insect larvae with the emergence of terrestrial adults—thus preventing export—and on terrestrial organisms that fall on the water surface (supporting import). This study demonstrates that the adaptation of salamanders to pond reproduction can alter food web linkages across ecosystem boundaries by enhancing the flux of materials and energy from terrestrial (i.e. forest) to the aquatic (i.e. pond) habitat.     

Neural processing as causal inference

Perception is about making sense, that is, understanding what events in the outside world caused the sensory observations. Consistent with this intuition, many aspects of human behavior confronting noise and ambiguity are well explained by principles of causal inference. Extending these insights, recent studies have applied the same powerful set of tools to perceptual processing at the neural level. According to these approaches, microscopic neural structures solve elementary probabilistic tasks and can be combined to construct hierarchical predictive models of the sensory input. This framework suggests that variability in neural responses reflects the inherent uncertainty associated with sensory interpretations and that sensory neurons are active predictors rather than passive filters of their inputs. Causal inference can account parsimoniously and quantitatively for non-linear dynamical properties in single synapses, single neurons and sensory receptive fields.     

An implantable fluid transfer system for treatment of impotence

The feasibility of using pressurized elastic tubing implanted within the penis as a means for volitional erection control is demonstrated. This is achieved by replacement of the corpora cavernosa with tubes that can assume either buckled or beam-like (erection) state. depending on fluid pressure. Two secondary pressurization systems are developed, one with and one without valves. This technique offers an alternative to rigid rod prosthesis implantation for treatment of impotence.     

Bilingualism and Bilingual Education in the United States

Bilingual Education for Hispanic Students in the United States . Joshua A. Fishman and Gary D. Keller , eds. New York: Teachers College Press, 1982. x + 502 pp. $18.95 (paper).
Bilingualism and Language Contact: Spanish, English, and Native American Languages . Florence Barkin, Elizabeth A. Brandt , and Jacob Ornstein-Galicia , eds. New York: Teachers College Press, 1982. xiii + 320 pp. $24.95 (cloth).
Spanish in the United States: Sociolinguistic Aspects . Jon Amastae and Lucia Elias-Olivares , eds. New York: Cambridge University Press, 1982. x + 434 pp. $14.00 (paper).
The New Bilingualism: An American Dilemma . Martin Ridge , ed. Proceedings of a Conference Sponsored by Center for Study of the American Experience. The Annenberg School of Communications, University of Southern California, May 1980. Los Angeles: University of Southern California Press, 1981. 272 pp. $20.00 (cloth).     

Schizonellin A and B,new glycolipids from Schizonella melanogramma

Two new glycolipids, schizonellin A and B, were isolated from cultures of the smut fungus Schizonella melanogramma. Their structures were elucidated by chemical degradation and spectroscopic methods. The schizonellins are active against Gram-positive bacteria, as well as against some Gram-negative bacteria and some fungi. DNA-, RNA- and protein-syntheses in Ehrlich carcinoma ascitic cells are inhibited simultaneously after addition of the schizonellins. Strong haemolytic action on bovine erythrocytes was observed.     

Die normalen Schwermetalle der Niere

Zusammenfassung 1. Anteile der in den Nieren vorhandenen Schwermetallspurenelemente Eisen, Zink, Kupfer, Cadmium, Blei lassen sich durch Schwefelwasserstoff in Sulfide umwandeln und durch physikalische Entwicklung sichtbar machen.2. Das Schwermetallaschenbild veranschaulicht besonders die Verteilung von Zink im Gewebe.3. Die nachweisbaren Anteile der Spurenelemente sind vorwiegend mobile Bestandteile des Gewebes. Sie liegen in den Deckzellen der Glomerula, an den Basalmembranen, in den Tubuluszellen und in den Kanälchenlichtungen. Ein schmaler Wall unter dem Bürstensaum der Hauptstückzellen bindet schwefelaffine Metalle: Zink, Kupfer, Blei, Quecksilber.4. Auf den Zink- und Kupfergehalt der Muskelzellen wird hingewiesen.5. Die Befunde werden diskutiert.Mit 15 TextabbildungenDurchgeführt mit Unterstützung der Deutschen Forschungsgemeinschaft.Herrn Professor Dr.K. Thomas zum 75. Geburtstag.     

Inactivation of adenovirus and simian virus 40 tumorigenicity in hamsters by vaccine processing methods

The effectiveness of the adenovirus vaccine inactivation process in destroying the tumorigenic potential for hamsters of adenoviruses, simian virus 40 (SV-40), and adenovirus-SV-40 hybrids was studied. Baby hamsters injected with untreated virus and with samples subjected to the complete inactivation process and to portions of the process were observed for tumor development for periods in excess of 300 days. Over 20,000 hamsters were injected. From 1 to 7 hr of exposure to formaldehyde at a concentration of 0.031 m at 37 C was sufficient to destroy the tumorigenicity observed in the nontreated preparations. Since the inactivation process included 48 hr of exposure at 37 C to 0.031 m formaldehyde plus treatment with ultraviolet (UV) and with beta-propiolactone (BPL), it was concluded that the process has a large margin of safety. Adenovirus isolates free from tumorigenic potential are difficult, if not impossible, to obtain. Therefore, a proven inactivation process appears to provide the best assurance for obtaining adenovirus vaccines free from such potential. Data presented suggest that the tumorigenic property of the viruses studied might be independent of the infectivity of the preparation. The tumorigenic property was found to be highly susceptible to formaldehyde, but less sensitive to BPL or UV treatment. In contrast, treatment with UV or BPL decreased viral infectivity more readily than tumorigenicity. The three-stage inactivation process (formaldehyde, UV, and BPL) inactivated both tumorigenicity and infectivity.