ALBERT

Notes: Abstract— Plasma profiles of reproductive and thyroid hormones were studied in captive striped bass Morone saxatilis during an 11-wk period encompassing the spawning season, and the effect of a sustained-release gonadotropin-releasing hormone agonist (GnRHa)-delivery system (GnRHa-implant) on milt production was evaluated. The highest percentage of spermiating fish was observed between mid-April and mid-May, and mean total expressible milt ranged from 3.5 to 6.0 mL/kg. Plasma gonadotropin II (GtH II) increased significantly, though inconsistently, during the spermiation period, whereas testosterone and 11-ketotestosterone levels declined continually. Plasma 17,20β-dihydroxy-4-pregnen-3-one and 17,20β,21-dihydroxy-4-pregnen-3-one remained low and unchanged during the peak of the spermiation period, while thyroid hormones were high and fluctuated without exhibiting a trend consistent with spermiation. The observed endocrine profiles suggest that captivity can diminish plasma GtH II and triiodothyronine levels in striped bass. Transfer of spermiating males from large holding tanks to small spawning tanks reduced total expressible milt after 14 d, but treatment with a GnRHa-implant restored milt volume, presumably due to the prolonged elevation of plasma GnRHa and GtH II induced by the GnRHa-implant. Also, treatment with the GnRHa-implant induced a two- to four-fold elevation of expressible milt for at least 20 d compared to control fish, while resulting in only a 5 to 15% decrease in sperm density. It appears that captivity and hatchery operations can diminish milt production in striped bass, and that GnRHa-delivery systems, via sustained elevation of plasma GtH II, can induce long-term enhancement in milt volume without affecting sperm density greatly.

Notes: Stomatal phosphoenolpyruvate carboxylase (PEPCase EC 4.1.1.31), extracted from abaxial epidermal peels of Vicia faba L. cv. Frühe Weiβkeimige, was partially purified by ammoniumsulfate precipitation, and molecular sieve (Sepharosc S-400) and ion exchange (DEAE-Sepharose) chromatography. The partially purified enzyme, essentially free of a PEPCase isoform existing in mesophyll and epidermal cells, had a specific activity of 300 nkat mg-1 protein at 25°C. Western immunoblot analysis revealed that the stomatal enzyme had two bands (M: of 110000 and 112000), crossreacting with PEPCase antibodies raised against PEPCase from Ka-lanchoe daigremontiana. The native molecular mass of the enzyme (467000) points to a tetrameric subunit structure. The temperature optimum was found to be 35°C; cold treatments of PEPCase before assaying were accompanied by inactivation. The energy of activation was calculated to 51 kJ mol-1. The kinetic behaviour of the enzyme at fixed MgCl2 concentrations is characterized by a pH optimum between pH 8.0–8.2 with or without 1 mM malate or 5 mM glucose-6-phosphate (Glc-6-P), but a combination of both effectors resulted in a shift of the optimum to pH 7.6. The enzyme showed a pH sensitive inhibition by 1 mM malate and an activation by Glc-6-P. At low pH (6–7), Glc-6-P was able to compensate for the malate induced inhibition of the enzyme. Malate and Glc-6-P both affected Km(PEP), drastically and influenced Vmax at pH 7, but not at pH 8.3. The inhibition constant of malate was determined to be 1.2 mM at pH 7. From the Dixon plot, a competitive inhibition of malate was assumed under defined assay conditions.

Notes: Abstract: The in situ temperature of the profundal sediment of Lake Constance is constant at 4°C. Methanogenic bacteria could not be detected at 6°C by the most probable number (MPN) technique using acetate and 〈inlineGraphic alt="inline image" href="urn:x-wiley:01686496:FEM1:FEM_1_mu1" location="equation/FEM_1_mu1.gif"/〉 as methanogenic substrates. Instead, homoacetogenic bacteria were detected on 〈inlineGraphic alt="inline image" href="urn:x-wiley:01686496:FEM1:FEM_1_mu2" location="equation/FEM_1_mu2.gif"/〉. At a higher temperature of 20°C, however, methanogenic bacteria were found in numbers of about 105 cells ml−1 with 〈inlineGraphic alt="inline image" href="urn:x-wiley:01686496:FEM1:FEM_1_mu3" location="equation/FEM_1_mu3.gif"/〉 and about 5 × 104 cells ml−1 with acetate. However, CH4 production was observed at both 4°C and 20°C. Production of CH4 was inhibited by chloroform and fluoroacetate and the accumulation of intermediary metabolites was measured. At the in situ temperature of 4°C, only acetate accumulated in presence of chloroform. Hydrogen partial pressures were at the same low value of about 0.5 Pa as in the uninhibited control. The amount of accumulated acetate was similar to that of CH4 in the uninhibited controls. Similar results were obtained with fluoroacetate which inhibits methanogenesis from acetate. Addition of H14CO3− did not result in the formation of 14CH4 after 28 days of incubation. However, [2-14C]acetate was immediately converted to 14CH4. The results indicate that methanogenesis at 4°C was exclusively due to acetate cleavage. At 20°C, by contrast, accumulation of H2 was observed in addition to that of acetate, propionate, valerate, caproate, methanol and isopropanol, when CH4 production was inhibited by chloroform. Thermodynamic calculations indicated that the accumulation of the fatty acids was a consequence of feedback inhibition by the accumulated H2. Balance calculations indicated that at 20° about 22% of the CH4 originated from reduction of CO2. Experiments with H14CO3− indicated that about 33% of the CH4 originated from 〈inlineGraphic alt="inline image" href="urn:x-wiley:01686496:FEM1:FEM_1_mu4" location="equation/FEM_1_mu4.gif"/〉 at 20°C. Thermodynamic calculations showed that homoacetogenesis from 〈inlineGraphic alt="inline image" href="urn:x-wiley:01686496:FEM1:FEM_1_mu5" location="equation/FEM_1_mu5.gif"/〉 was endergonic, whereas methanogenesis from acetate or 〈inlineGraphic alt="inline image" href="urn:x-wiley:01686496:FEM1:FEM_1_mu6" location="equation/FEM_1_mu6.gif"/〉 was exergonic at both 4°C and 20°C. Low sediment temperatures obviously limited methanogenesis from 〈inlineGraphic alt="inline image" href="urn:x-wiley:01686496:FEM1:FEM_1_mu7" location="equation/FEM_1_mu7.gif"/〉 for reasons other than thermodynamics. Simultaneously, degradation processes seemed to be dominated by homoacetogenic degradation of organic matter followed by acetoclastic methanogenesis. However, increase of temperature resulted in a dramatic shift of the degradation pathway enhancing the role of H2 as an intermediate.

Notes: Bacillus cereus strains involved in food poisoning cases of the diarrheal type may produce two different enterotoxin complexes. To facilitate the identification of hemolysin BL-enterotoxin complex (HBL) and/or the nonhemolytic enterotoxin (NHE) producing colonies a colony immunoblot procedure was developed, which allows a fast and easy identification of the respective colonies from blood agar plates. The enterotoxins were transferred from the blood agar medium to a nitrocellulose membrane and the immobilized toxins were probed with monoclonal antibodies. The antibodies 2A3 and 1A8 allowed the specific detection of the B component of HBL and the nheA component of NHE. The assay enabled the reliable identification of HBL expressing colonies and differentiation from NHE producing but HBL negative colonies.

Notes: Bacillus cereus causes two types of gastrointestinal diseases: emesis and diarrhea. The emetic type of the disease is attributed to the heat-stable depsipeptide cereulide and symptoms resemble Staphylococcus aureus intoxication, but there is no rapid method available to detect B. cereus strains causing this type of disease. In this study, a polymerase chain reaction (PCR) fragment of unknown function was identified, which was shown to be specific for emetic toxin producing strains of B. cereus. The sequence of this amplicon was determined and a PCR assay was developed on this basis. One hundred B. cereus isolates obtained from different food poisoning outbreaks and diverse food sources from various geographical locations and 29 strains from other species belonging to the B. cereus group were tested by this assay. In addition, 49 non-B. cereus group strains, with special emphasis on food pathogens, were used to show that the assay is specific for emetic toxin producing B. cereus strains. The presented PCR assay is the first molecular tool for the rapid detection of emetic toxin producing B. cereus strains.

Notes: Monthly (April to November) hydroacoustic surveys and parallel gillnet catches were used to determine vendace Coregonus albula abundance, biomass and population dynamics in a deep oligotrophic lake. By hydroacoustic surveys, recruitment of 0+ year vendace could clearly be detected. In contrast, gillnet catches resulted in low numbers of 0+ year fish, and similarly under-represented proportions of the oldest vendace. Consequently, the correlation between hydroacoustics and gillnets with respect to fish numbers and geometric mean fish total length was high only for the age groups 1 + to 4+ years. Annual variability in hydroacoustic estimates offish abundance and biomass was high (CV=26–29%) which reflects the seasonal population dynamics of vendace.

Notes: The effect of nitrogen and carbon status on the regulation of glutamine synthetase (GS) and glutamate synthase (GOGAT) were investigated in Corynebacterium glutamicum 13032. Under carbon-sufficient, nitrogen-limiting conditions, GS and GOGAT activities were five- and seven-fold higher, respectively, and transcription of the corresponding genes (glnA and gltBD) was similarly induced. GS activity was also induced in complete medium with added glucose, while GOGAT activity was unaffected. Under carbon-limiting, nitrogen-limiting conditions, the level of GS induction was reduced approximately three-fold, whereas GOGAT activity did not respond. Disruption of the hkm gene, encoding a putative histidine kinase upstream of gltBD, reduced the levels of GOGAT activity two-fold under both nitrogen-rich and nitrogen-limiting conditions. Promoter studies using a hkm–chloramphenicol acetylase fusion plasmid revealed that transcription of hkm is moderately induced (ca. 1.5-fold) by nitrogen starvation, indicating that the Hkm protein may play a role in signal transduction of the nutritional status of the growth medium.

Notes: A complete prograde P–T path, defined by 10 calculated P–T fields in succession, is recognized from metapelites by using geothermobarometry on garnet-bearing assemblages with microstructural control. Overstacking of several tectonic units during an early Variscan continental collision explains the complex prograde P–T history. Isostatic uplift and deformation controlled the retrograde P–T path.Deformation with changing character acted continuously during all stages of the evolution of the Austroalpine basement complex. After the intrusion of Caledonian granitoids, metapelites and magmatic rocks suffered a shearing deformation D1–D2, which produced sheath folds as well as the main foliation S2. Spessartine-rich first-generation garnets, situated in microlithons enclosed by S2, record the onset of shearing under increasing high-pressure–low-temperature conditions (7 kbar/380°C). Geothermobarometry on second-generation garnets which have been rotated during growth indicates isothermal decompression from 9 kbar to 5 kbar/500°C and subsequent recompression/heating during continuing shearing. This is explained by overthrusting of a tectonic unit (unit 2) from NE to SW upon the micaschist unit (unit 1), followed by isostatic uplift and further overstocking of a third unit (unit 3). The resulting Pmax of 12 kbar at 650°C and further increasing temperatures up to 680°C accompanied by decompression have been calculated using a third generation of garnets. These high-pressure–high-temperature conditions may explain the occurrence of eclogitic metabasites in adjacent regions.Staurolite and kyanite first appeared under decreasing pressures at the last stage of prograde P–T evolution. Shortening deformation D3 and simultaneous growth of typical amphibolite facies minerals (staurolite 2, kyanite 2, sillimanite, andalusite) occurred during the retrograde path. A final step of Variscan evolution was marked by an oppositely directed shearing D4 (at T 〉 300°C and P 〉 3 kbar), possibly indicating backthrusting or extension.Apart from acid intrusions, no signs of a previous Caledonian thermotectonic history were found in the area to the south of the Defereggen–Antholz–Vals Line.

Notes: Structure and formation of aluminosilicate hydrogels were investigated as a function of chemical composition. Oscillatory rheometry was used to measure the dynamic moduli, G‘ and G“, of the gels during setting. The formation of aluminosilicate hydrogels was monitored over time as a function of the storage modulus for gels of low solids volumes, φ 〈 0.030. Overall gel strength correlated well to the fractal dimension, D, observed by neutron scattering. Scattering data were interpreted using the power law, and the Guinier relationship was used to determine the size of the constructing colloidal/gel particles. Aluminosilicate hydrogels were observed to consist of large fractal aggregates of indeterminable size constructed from smaller subunits of ∼45 Å in dimension. Structure and formation of the gels were highly dependent on [Al2O3] and [Na2O] content.