Gut evacuation rates and ingestion rates of Eudiaptomus graciloides measured by means of the gut fluorescence method

Journal of Plankton Research, 8, 973–983, 1986 FIg. 2. Time-dependent changes in the gut content (percentageof initial ng pigment) of E. gro.ciloides at different temperaturesunder simultaneous feeding. Fig. 4. The relationship between instantaneous evacuation rateand temperature of E. graciloides. The regresston equation forfeeding animals: y = 0.0044 e(0.141 ) (r² = 0.90). For comparisonthe results of non-feeding animals are indicated with open circles.     

Detection of resistance of lactic acid bacteria to a mixture of the hop analogue compounds tetrahydroiso-alpha-acids by noninvasive measurement of intracellular pH

AIMS: To examine the resistance of beer isolates of lactic acid bacteria (LAB) towards a mixture of tetrahydroiso-alpha-acids (Tetra) by growth experiments as well as by measurement of intracellular pH. METHODS AND RESULTS: Beer LAB isolates were identified to species level by SDS-PAGE of whole-cell proteins. Beer isolates of Lactobacillus brevis showed better ability for growth in the presence of Tetra than nonbeer isolates of the L. brevis or other species of LAB including beer and nonbeer isolates. The antimicrobial effect of Tetra was also examined by noninvasive measurement of intracellular pH by fluorescence ratio imaging microscopy for selected beer isolates of L. brevis and Pediococcus inopinatus. Strains of L. brevis showing limited decrease of intracellular pH during exposure to Tetra also showed better ability for growth in the presence of these compounds as well as in commercial beer products. CONCLUSIONS: It was possible to apply a method for noninvasive measurement of intracellular pH to predict the resistance of beer spoilage LAB towards the Tetra hop analogue compounds. SIGNIFICANCE AND IMPACT OF THE STUDY: This study demonstrated the usability of a new rapid method for detecting hop-resistant variants of known beer spoilage LAB species.     

Relationship between growth and pH gradients of individual cells of Debaryomyces hansenii as influenced by NaCl and solid substrate

AIMS: To examine the relationship between the growth and pH gradients of Debaryomyces hansenii at a single-cell level. METHODS AND RESULTS: Using bioimaging techniques, the cell areas and early pH gradients (Delta pH(10)), i.e. the pH gradients determined 10 min after initiation of experiments, were determined for single cells of two D. hansenii strains in fluid and on solid (agar) substrate with and without 8% (w/v) NaCl. The combination of NaCl and solid substrate prolonged the growth initiation of both D. hansenii strains additively. In all our experiments, primarily two groups of cells existed; a vital group consisting of growing single cells with intact early pH gradients, and a group of dead cells without early pH gradients. CONCLUSIONS: Our results show that growth initiation of the D. hansenii cells is severely affected by NaCl and to a lesser extent by the type of substrate in an additive and strain dependent way. Moreover, the early pH gradient of a vital D. hansenii cell cannot be correlated with the rate of its subsequent growth. SIGNIFICANCE AND IMPACT OF THE STUDY: Our study reveals new knowledge on the growth and pH gradients of D. hansenii on solid surfaces in the presence of NaCl.     

A Flow-Cytometric Gram-Staining Technique for Milk-Associated Bacteria

A Gram-staining technique combining staining with two fluorescent stains, Oregon Green-conjugated wheat germ agglutinin (WGA) and hexidium iodide (HI) followed by flow-cytometric detection is described. WGA stains gram-positive bacteria while HI binds to the DNA of all bacteria after permeabilization by EDTA and incubation at 50°C for 15 min. For WGA to bind to gram-positive bacteria, a 3 M potassium chloride solution was found to give the highest fluorescence intensity. A total of 12 strains representing some of the predominant bacterial species in bulk tank milk and mixtures of these were stained and analyzed by flow cytometry. Overall, the staining method showed a clear differentiation between gram-positive and gram-negative bacterial populations. For stationary-stage cultures of seven gram-positive bacteria and five gram-negative bacteria, an average of 99% of the cells were correctly interpreted. The method was only slightly influenced by the growth phase of the bacteria or conditions such as freezing at −18°C for 24 h. For any of these conditions, an average of at least 95% of the cells were correctly interpreted. When stationary-stage cultures were stored at 5°C for 14 days, an average of 86% of the cells were correctly interpreted. The Gram-staining technique was applied to the flow cytometry analysis of bulk tank milk inoculated with Staphylococcus aureus and Escherichia coli. These results demonstrate that the technique is suitable for analyzing milk samples without precultivation.     

Functional characterization of the vertebrate primary ureter: Structure and ion transport mechanisms of the pronephric duct in axolotl larvae (Amphibia)

Background  

Three kidney systems appear during vertebrate development: the pronephroi, mesonephroi and metanephroi. The pronephric duct is the first or primary ureter of these kidney systems. Its role as a key player in the induction of nephrogenic mesenchyme is well established. Here we investigate whether the duct is involved in urine modification using larvae of the freshwater amphibian Ambystoma mexicanum (axolotl) as model.     

Susceptibility of spinosad in Musca domestica (Diptera: Muscidae) field populations

The toxicity of spinosad was determined in one susceptible and five insecticide-resistant laboratory strains of house fly, Musca domestica L. Spinosad was relatively slow-acting, but highly toxic to house flies. In a feeding bioassay, spinosad LC50 at 72 h was 0.51 microg of spinosad per gram of sugar, making it 6.3- and 3.5-fold more toxic to house flies compared with azamethiphos and methomyl, respectively. In topical application bioassay, the LD50 at 48 h of spinosad in susceptible house flies was 40 ng per 20 mg of house fly, making spinosad less toxic than the pyrethroid bioresmethrin synergized by piperonyl butoxide and the organophosphate dimethoate. The insecticide-resistant laboratory strains had resistance factors to spinosad at LC50 in feeding bioassay from 1.5 to 5.5 and at LD50 in topical application bioassay from 2.5 to 4.7, indicating that in house fly cross-resistance to the major insecticide classes will not initially be of major concern for the use of spinosad for house fly control. The toxicity of spinosad was also evaluated against 31 field populations of house flies collected from livestock farms across Denmark. The field populations were 2.2- to 7.5-fold resistant to spinosad at 72 h in feeding bioassay, but based on steep slopes in the bioassay and the limited variation of spinosad toxicity against the various field populations, we consider the field populations to be spinosad-susceptible. We propose a diagnostic dose of 12 microg of spinosad per gram of sugar in feeding bioassay with impregnated sugar for determination of resistant house flies, which is 10x the LC95 of the susceptible strain WHO and approximately = 2x the LD95 of the field populations. Spinosad showed no substantial cross-resistance to the pyrethroid bioresmethrin synergized by piperonyl butoxide, the anticholinesterases dimethoate, azamethiphos, methomyl, and spinosad in house fly field populations.     

Where might the western Svalbard tundra be vulnerable to pink‐footed goose (Anser brachyrhynchus) population expansion? Clues from species distribution models

Pink-footed geese ( Anser brachyrhynchus ) breed in the Arctic, where their populations have doubled since the 1980s. There is concern that nesting geese disturb the fragile tundra and lead to a trophic cascade with strong top-down effects on vegetation and soil processes. A better understanding of the distribution of geese and factors that influence nest site selection is needed to highlight potential problem areas and assess the potential for further population expansion. To help infer the importance of environmental variables on nest site selection, we built generalized additive models using nest observations collected in 2003 and 2004 from the Sassendalen valley, Svalbard, along with a suite of geographical information system explanatory predictors. The fit of the models was very high (explaining over 72% of the deviance), and predictive power to independent samples indicated useful predictions that could discriminate between presences and absence of nests very well (area under the receiver operating characteristic curves exceeded 0.88). Significant predictors of nest site selection included elevation, slope, aspect, percentage of snow cover, percentage of foraging habitat cover, and a spatial autocovariate. Spatial predictions were applied to the broader Nordenskiöldsland region of Svalbard and highlighted the importance of previously unsurveyed locations for nesting.     

Burden of Hospital Admission and Repeat Angiography in Angina Pectoris Patients with and without Coronary Artery Disease: A Registry-Based Cohort Study

Aims

To evaluate risk of hospitalization due to cardiovascular disease (CVD) and repeat coronary angiography (CAG) in stable angina pectoris (SAP) with no obstructive coronary artery disease (CAD) versus obstructive CAD, and asymptomatic reference individuals.

Methods and Results

We followed 11,223 patients with no prior CVD having a first-time CAG in 1998–2009 due to SAP symptoms and 5,695 asymptomatic reference individuals from the Copenhagen City Heart Study through registry linkage for 7.8 years (median). In recurrent event survival analysis, patients with SAP had 3–4-fold higher risk of hospitalization for CVD irrespective of CAG findings and cardiovascular comorbidity. Multivariable adjusted hazard ratios(95%CI) for patients with angiographically normal coronary arteries was 3.0(2.5–3.5), for angiographically diffuse non-obstructive CAD 3.9(3.3–4.6) and for 1–3-vessel disease 3.6–4.1(range)(all P<0.001). Mean accumulated hospitalization time was 3.5(3.0–4.0)(days/10 years follow-up) in reference individuals and 4.5(3.8–5.2)/7.0(5.4–8.6)/6.7(5.2–8.1)/6.1(5.2–7.4)/8.6(6.6–10.7) in patients with angiographically normal coronary arteries/angiographically diffuse non-obstructive CAD/1-, 2-, and 3-vessel disease, respectively (all P<0.05, age-adjusted). SAP symptoms predicted repeat CAG with multivariable adjusted hazard ratios for patients with angiographically normal coronary arteries being 2.3(1.9–2.9), for angiographically diffuse non-obstructive CAD 5.5(4.4–6.8) and for obstructive CAD 6.6–9.4(range)(all P<0.001).

Conclusions

Patients with SAP symptoms and angiographically normal coronary arteries or angiographically diffuse non-obstructive CAD suffer from considerably greater CVD burdens in terms of hospitalization for CVD and repeat CAG compared with asymptomatic reference individuals even after adjustment for cardiac risk factors and exclusion of cardiovascular comorbidity as cause. Contrary to common perception, excluding obstructive CAD by CAG in such patients does not ensure a benign cardiovascular prognosis.     

Multiple α-Glucoside Transporter Genes in Brewer’s Yeast

Maltose and maltotriose are the two most abundant fermentable sugars in brewer’s wort, and the rate of uptake of these sugars by brewer’s yeast can have a major impact on fermentation performance. In spite of this, no information is currently available on the genetics of maltose and maltotriose uptake in brewing strains of yeast. In this work, we studied 30 brewing strains of yeast (5 ale strains and 25 lager strains) with the aim of examining the alleles of maltose and maltotriose transporter genes contained by them. To do this, we hybridized gene probes to chromosome blots. Studies performed with laboratory strains have shown that maltose utilization is conferred by any one of five unlinked but highly homologous MAL loci (MAL1 to MAL4 and MAL6). Gene 1 at each locus encodes a maltose transporter. All of the strains of brewer’s yeast examined except two were found to contain MAL11 and MAL31 sequences, and only one of these strains lacked MAL41. MAL21 was not present in the five ale strains and 12 of the lager strains. MAL61 was not found in any of the yeast strains. In three of the lager strains, there was evidence that MAL transporter gene sequences occurred on chromosomes other than those known to carry MAL loci. Sequences corresponding to the AGT1 gene, which encodes a transporter of several α-glucosides, including maltose and maltotriose, were detected in all but one of the yeast strains. Homologues of AGT1 were identified in three of the lager strains, and two of these homologues were mapped, one to chromosome II and the other to chromosome XI. AGT1 appears to be a member of a family of closely related genes, which may have arisen in brewer’s yeast in response to selective pressure.