The South African coelacanths — an account of what is known after three submersible expeditions

Using the manned submersible Jago, the habits, distribution and number of coelacanths within all main submarine canyons of the Greater St Lucia Wetland Park were studied during 47 survey dives, with a total bottom time of 166 hours at depths ranging from 46 to 359 m, between 2002 and 2004. Twenty-four individuals were positively identified from three of the canyons, primarily from inside caves at or close to the canyon edges at depths of 96–133 m with water temperatures between 16 and 22.5°C. The population size of coelacanths within the canyons is assumed to be relatively small; coelacanths are resident but not widespread nor abundant within the park

Methyl Coenzyme M Reductase (mcrA) Gene Abundance Correlates with Activity Measurements of Methanogenic H2/CO2-Enriched Anaerobic Biomass

Biologically produced methane (CH4) from anaerobic digesters is a renewable alternative to fossil fuels, but digester failure can be a serious problem. Monitoring the microbial community within the digester could provide valuable information about process stability because this technology is dependent upon the metabolic processes of microorganisms. A healthy methanogenic community is critical for digester function and CH4 production. Methanogens can be surveyed and monitored using genes and transcripts of mcrA, which encodes the α subunit of methyl coenzyme M reductase – the enzyme that catalyses the final step in methanogenesis. Using clone libraries and quantitative polymerase chain reaction, we compared the diversity and abundance of mcrA genes and transcripts in four different methanogenic hydrogen/CO2 enrichment cultures to function, as measured by specific methanogenic activity (SMA) assays using H2/CO2. The mcrA gene copy number significantly correlated with CH4 production rates using H2/CO2, while correlations between mcrA transcript number and SMA were not significant. The DNA and cDNA clone libraries from all enrichments were distinctive but community diversity also did not correlate with SMA. Although hydrogenotrophic methanogens dominated these enrichments, the results indicate that this methodology should be applicable to monitoring other methanogenic communities in anaerobic digesters. Ultimately, this could lead to the engineering of digester microbial communities to produce more CH4 for use as renewable fuel

Edaq530: a transparent, open-end and open-source measurement solution in natural science education

We present Edaq530, a low-cost, compact and easy-to-use digital measurement solution consisting of a thumb-sized USB-to-sensor interface and a measurement software. The solution is fully open-source, our aim being to provide a viable alternative to professional solutions. Our main focus in designing Edaq530 has been versatility and transparency. In this paper, we shall introduce the capabilities of Edaq530, complement it by showing a few sample experiments, and discuss the feedback we have received in the course of a teacher training workshop in which the participants received personal copies of Edaq530 and later made reports on how they could utilise Edaq530 in their teaching

Ischemic preconditioning attenuates portal venous plasma concentrations of purines following warm liver ischemia in man

Background/Aims: Degradation of adenine nucleotides to adenosine has been suggested to play a critical role in ischemic preconditioning (IPC). Thus, we questioned in patients undergoing partial hepatectomy whether (i) IPC will increase plasma purine catabolites and whether (ii) formation of purines in response to vascular clamping (Pringle maneuver) can be attenuated by prior IPC. Methods: 75 patients were randomly assigned to three groups: group I underwent hepatectomy without vascular clamping; group II was subjected to the Pringle maneuver during resection, and group III was preconditioned (10 min ischemia and 10 min reperfusion) prior to the Pringle maneuver for resection. Central, portal venous and arterial plasma concentrations of adenosine, inosine, hypoxanthine and xanthine were determined by high-performance liquid chromatography. Results: Duration of the Pringle maneuver did not differ between patients with or without IPC. Surgery without vascular clamping had only a minor effect on plasma purine transiently increased. After the Pringle maneuver alone, purine plasma concentrations were most increased. This strong rise in plasma purines caused by the Pringle maneuver, however, was significantly attenuated by IPC. When portal venous minus arterial concentration difference was calculated for inosine or hypoxanthine, the respective differences became positive in patients subjected to the Pringle maneuver and were completely prevented by preconditioning. Conclusion: These data demonstrate that (i) IPC increases formation of adenosine, and that (ii) the unwanted degradation of adenine nucleotides to purines caused by the Pringle maneuver can be attenuated by IPC. Because IPC also induces a decrease of portal venous minus arterial purine plasma concentration differences, IPC might possibly decrease disturbances in the energy metabolism in the intestine as well. Copyright (C) 2005 S. Karger AG, Basel

Prospects for measuring the 229Th isomer energy using a metallic magnetic microcalorimeter

The Thorium-229 isotope features a nuclear isomer state with an extremely low energy. The currently most accepted energy value, 7.8 +- 0.5 eV, was obtained from an indirect measurement using a NASA x-ray microcalorimeter with an instrumental resolution 26 eV. We study, how state-of-the-art magnetic metallic microcalorimeters with an energy resolution down to a few eV can be used to measure the isomer energy. In particular, resolving the 29.18 keV doublet in the \gamma-spectrum following the \alpha-decay of Uranium-233, corresponding to the decay into the ground and isomer state, allows to measure the isomer transition energy without additional theoretical input parameters, and increase the energy accuracy. We study the possibility of resolving the 29.18 keV line as a doublet and the dependence of the attainable precision of the energy measurement on the signal and background count rates and the instrumental resolution.Comment: 32 pages, 8 figures, eq. (3) correcte

Shape-memory polymers as flexible resonator substrates for continuously tunable organic DFB lasers

We introduce shape-memory polymers (SMP) as substrate material for active optical devices. As an exemplary application we build a tunable organic semiconductor distributed feedback (DFB) laser. Hence, we transfer a second order Bragg grating with a period of 400 nm into SMP foils by hot embossing. The composite organic gain medium Alq3:DCM evaporated on the SMP substrate serves as laser active material. Mechanical stretching of the substrate increases the grating period temporarily and triggering the shape-memory effect afterwards reduces the period on demand. In this way, we can adjust the grating period to achieve a broad continuously tuning of the laser emission wavelength by 30 nm

Fishes of the deep demersal habitat at Ngazidja (Grand Comoro) Island, Western Indian Ocean

Underwater observations of the coelacanth, Latimeria chalumnae</I> Smith, 1939, from a research submersible provided opportunities to study the deep demersal fish fauna at the Comoro Islands. The demersal habitat in depths of 150-400 m at the volcanic island of Ngazidja is low in fish diversity and biomass, compared with the shallow-water coral reef habitat of Ngazidja or the deep demersal habitats of other localities in the Indo-Pacific region. The resident deep demersal fish fauna at Ngazidja is dominated by the coelacanth, an ancient predator that is specially adapted for this low-energy environment. Other large fish predators are scarce in this environment, because of the heavy fishing pressure from local fishermen. Eighty-nine fish taxa (including 65 recognizable species) were recorded from videotapes, photographs, visual observations, fishermen's catches and ancillary attempts to sample the fish fauna with baited fish traps, gill nets, and hook and line. Although no coelacanth feeding events were seen, seven fish species are known from coelacanth stomach contents, and 64 other fish species in this habitat are considered potential prey of this dominant predator

Interactions of fishes with particular reference to coelacanths in the canyons at Sodwana Bay and the St. Lucia Protected Area of South Africa

The deep demersal fish fauna at depths of 100–400min canyons off the St Lucia Marine Protected Area along the north coast of KwaZulu-Natal is compared with similar fish communities at the Comoro Islands and in the Indo-Pacific region. Fifty-four fish species were seen or photographed from the submersible Jago or by the discovery team of scuba divers in the coelacanth, Latimeria chalumnae, habitat of the canyons off Sodwana Bay. An additional 94 fish species known from depths of 100–200 m along the coast of northern KwaZulu-Natal are likely to occur in the canyon habitat. The fish fauna of the Sodwana canyons shares at least 18 species with the deep demersal fish community off tropical coral reefs of the Indo-Pacific region. Thirty-seven of the Sodwana canyon fishes are also known from the coelacanth habitat in the Comoros