Temporal variability of the Atlantic meridional overturning circulation at 26.5 degrees N

The vigor of Atlantic meridional overturning circulation (MOC) is thought to be vulnerable to global warming, but its short-term temporal variability is unknown so changes inferred from sparse observations on the decadal time scale of recent climate change are uncertain. We combine continuous measurements of the MOC (beginning in 2004) using the purposefully designed transatlantic Rapid Climate Change array of moored instruments deployed along 26.5 degrees N, with time series of Gulf Stream transport and surface-layer Ekman transport to quantify its intra-annual variability. The year-long average overturning is 18.7 +/- 5.6 sverdrups (Sv) (range: 4.0 to 34.9 Sv, where 1 Sv = a flow of ocean water of 10(6) cubic meters per second). Interannual changes in the overturning can be monitored with a resolution of 1.5 Sv.     

Tracing the origin and fate of NOx in the Arctic atmosphere using stable isotopes in nitrate

Atmospheric nitrogen oxides (NOx =NO+ NO2) play a pivotal role in the cycling of reactive nitrogen (ultimately deposited as nitrate) and the oxidative capacity of the atmosphere. Combined measurements of nitrogen and oxygen stable isotope ratios of nitrate collected in the Arctic atmosphere were used to infer the origin and fate of NOx and nitrate on a seasonal basis. In spring, photochemically driven emissions of reactive nitrogen from the snowpack into the atmosphere make local oxidation of NOx by bromine oxide the major contributor to the nitrate budget. The comprehensive isotopic composition of nitrate provides strong constraints on the relative importance of the key atmospheric oxidants in the present atmosphere, with the potential for extension into the past using ice cores.     

Vitamin D and sterol composition of 10 types of mushrooms from retail suppliers in the United States

Vitamin D(2) (ergocalciferol) and sterols were analyzed in mushrooms sampled nationwide in the United States to update the USDA Nutrient Database for Standard Reference. Vitamin D(2) was assayed using HPLC with [(3)H]-vitamin D(3) internal standard and sterols by GC-FID mass spectrometric (MS) confirmation. Vitamin D(2) was low (0.1-0.3 μg/100 g) in Agaricus bisporus (white button, crimini, portabella) and enoki, moderate in shiitake and oyster (0.4-0.7 μg/100 g), and high in morel, chanterelle, maitake (5.2-28.1 μg/100 g) and UV-treated portabella (3.4-20.9 μg/100 g), with significant variability among composites for some types. Ergosterol (mg/100 g) was highest in maitake and shiitake (79.2, 84.9) and lowest in morel and enoki (26.3, 35.5); the range was <10 mg/100 g among white button composites but 12-50 mg/100 g among samples of other types. All mushrooms contained ergosta-5,7-dienol (22,23-dihydroergosterol) (3.53-18.0 mg/100 g) and (except morel) ergosta-7-enol. Only morel contained brassicasterol (28.6 mg/100 g) and campesterol (1.23-4.54 mg/100 g) and no ergosta-7,22-dienol. MS was critical in distinguishing campesterol from ergosta-7,22-dienol.     

Antimicrobial potential of egg yolk ovoinhibitor, a multidomain Kazal-like inhibitor of chicken egg

Chicken egg ovoinhibitor is a multidomain Kazal-type serine protease inhibitor with unknown function. Comparison of expression between different tissues indicated that ovoinhibitor is highly expressed in the magnum and liver followed by the uterus, which secrete egg white, egg yolk, and eggshell precursors, respectively. The results also revealed that ovoinhibitor expression is increased in the liver during sexual maturation followed by a subsequent decrease in mature hens. Ovoinhibitor was purified from the egg yolk plasma from nonfertilized eggs using two consecutive affinity chromatographies and gel filtration. Purified egg yolk ovoinhibitor was shown to inhibit trypsin and subtilisin. It was shown that purified egg yolk ovoinhibitor exhibited antimicrobial activities against Bacillus thuringiensis . The results suggest that this anti-protease plays a significant role in antibacterial egg defense against Bacillus spp., preventing contamination of table eggs (nonfertilized eggs) and protecting the chick embryo (fertilized eggs).     

Comparison of a rebound and an applanation tonometer for measuring intraocular pressure in normal rabbits

Objective To compare intraocular pressure (IOP) measurements made on healthy adult rabbits without the effect of tranquilizers using the new applanation tonometer, Tono‐Pen Avia^®, and the rebound tonometer Tonovet^®. Methods Intraocular pressure was measured throughout the day (6:00, 9:00, 12:00, 15:00, and 18:00 h) in 38 adult New Zealand White rabbits (76 eyes). The animals were 20 males and 18 females, with a mean weight of 3.5 kg and an average age of 6 months. A complete ocular exam (including Schirmer tear test, fluorescein staining, slit‐lamp biomicroscopy, and direct ophthalmoscopy) was performed on all animals at the beginning of the trial. Rebound tonometry was performed, and after 10 min, anesthetic drops were instilled and applanation tonometry was carried out. IOP values obtained using the two techniques were analyzed statistically. Results The mean IOP was 9.51 ± 2.62 mmHg with Tonovet^®, and 15.44 ± 2.16 mmHg with the Tono‐Pen Avia^®. Significant differences between measurements with the two tonometers were observed (P < 0.001). The linear regression equation describing the relationship between the two tonometers was y = 0.4923x + 10.754 (y = Tonovet^® and x = Tono‐Pen Avia^®). High IOPs were recorded in the early measurements (6:00), but the average IOPs from both devices were statistically similar throughout the day (P = 0.086). The correlation coefficient was r² = 0.357. No significant difference in IOP regarding gender was observed. Conclusion The Tono‐Pen Avia^® recorded higher levels of IOP compared with the Tonovet^®. Early in the day, the IOP of rabbits was higher than later in the day, regardless of the tonometer used.     

Soybean cultivar performance in the presence of soybean Asian rust,in relation to chemical control programs

Soybean rust is caused by an obligate parasite (Phakopsora pachyrhizi) which has spread in Brazil in each new season since 2001 and, despite the efforts to control the disease, losses have occurred every year. Its control demands several tactics amongst which chemical control with fungicides is the main method and remains indispensable. Control strategies such as the use of cultivars with partial resistance are desirable, but are not yet commercially available. The present study analyzed the existing differences in the reactions of short, medium and long cycle soybean cultivars against Asian rust and their responses to fungicide sprays. The experiment was conducted at Uberlandia-MG, Brazil, under field conditions from December 2007 to May 2008, in the Syngenta Seeds Experimental Station. The high pressure of the disease in the experiment simulated the natural pressure that the disease often reaches in Brazil. The studied variables were: visual severity (percentage of infected leaf area), percentage defoliation and productivity (kg ha⁻¹). Disease severity was expressed as AUDPC (area under disease progress curve). Variance analysis and comparison of means by the Tukey test (5% significance) were done for all variables studied. Significant differences were observed between cultivar effects and chemical control programs. The results obtained here indicate that the cultivars M-Soy 8199RR and Emgopa 315RR were less susceptible to disease, and that a control program termed “monitoring” (in which the appearance of new pustules of the pathogen were monitored to make the decision at each fungicide spray) was the most effective.     

Does nectar reward affect rarity and extinction probabilities of orchid species? An assessment using historical records from Belgium and the Netherlands

The long-term persistence of plant populations may partly depend on pollination processes and seed production. The exact role of pollination in determining plant population viability still remains largely unclear. Orchid species have often been shown to be pollinator limited. Especially, non-rewarding species are characterized by infrequent pollinator visits and low seed set. Therefore, it can be hypothesized that, if overall population fitness of orchid species is influenced by seed production, non-rewarding species should be more prone to local extinction than rewarding species. To study the importance of nectar reward on orchid persistence, we collected historical records about the distribution of 32 orchid species in Flanders (Belgium) and 37 orchid species in the Netherlands. For both regions, present distribution patterns were compared with historical data. Between 1930 (Flanders) or 1950 (the Netherlands) and 2000, 26 (81%) species showed decreases in distribution range in Flanders, eight of which had gone extinct, whereas 29 (78%) species showed declines in distribution area in the Netherlands, five of which went extinct. Contrary to previously reported results, orchid distribution patterns were not related to nectar reward. There was also no significant relationship between nectar reward and extinction for both regions. Orchids typically occurring in wet grasslands and heathlands suffered greater losses than orchids typically confined to forest habitats or calcareous grasslands. We conclude that the production of nectar does not represent a safeguard for local extinction of orchid species. Habitat loss and other deterministic threats associated with habitat fragmentation and deterioration are more important determinants of orchid persistence.     

Comparison of two microalgal diets. 2. Influence on odorant composition and organoleptic qualities of raw oysters (Crassostrea gigas)

Oyster farming is of real economic interest in France. Oyster farmers attach more and more importance to improving the growth and the quality of their oysters. Some fatty acids known to be aroma precursors originate from microalgae such as Skeletonema costatum and Tahitian isochrysis clone. These microalgae were used to fatten oysters in order to observe their role in the development of oysters' aroma. This study shows that the profile of fatty acids of oysters is influenced by the contribution of fatty acids from the two microalgae (as reported in the first paper in this series: Pennarun, A.-L.; Prost, C.; Haure, J.; Demaimay, M. Comparison of Two Microalgal Diets. 1. Influence on the Biochemical and Fatty Acid Compositions of Raw Oysters (Crassostrea gigas). J. Agric. Food Chem. 2003, 51, 2006-2010 (in this issue)]. As a consequence, a microalgal diet causes changes in oysters' aroma composition. Aroma concentration depends on the content of fatty acids that are aroma precursors in oysters. Some aromas are characteristic of the diet of S. costatum, such as 6-methyl-5-hepten-2-one (ether odor), and others are characteristic of T. isochrysis, such as 3-nonyne (cucumber, marine odor), 6-(E)-nonen-1-ol (green and fresh odor), and 4-ethylbenzaldehyde (aniseed odor). Moreover, the organoleptic qualities (odor, taste, and texture) of oysters are modified by the diet of microalgae.