Mesoscale eddies drive increased silica export in the subtropical Pacific Ocean

Mesoscale eddies may play a critical role in ocean biogeochemistry by increasing nutrient supply, primary production, and efficiency of the biological pump, that is, the ratio of carbon export to primary production in otherwise nutrient-deficient waters. We examined a diatom bloom within a cold-core cyclonic eddy off Hawaii. Eddy primary production, community biomass, and size composition were markedly enhanced but had little effect on the carbon export ratio. Instead, the system functioned as a selective silica pump. Strong trophic coupling and inefficient organic export may be general characteristics of community perturbation responses in the warm waters of the Pacific Ocean.     

Light-stimulated electrical responses from skin

When skin is exposed to an intense flash of light, an early electrical response can be detected from its surface. The signals that occur during the first milliseconds after the flash are similar to electrical signals recently observed in the eye from the cell layers containing melanin. Possibly the melanin in skin augments, but does not directly generate, this early electrical response. In addition, a late response, which arises hundreds of milliseconds after the flash, also occurs in skin. Unlike the early response, the late response is sensitive only to violet and shorter wavelengths of light and hence is probably mediated by a pigment other than melanin.     

The rediscovery of a lost frog: Arthroleptis troglodytes Poynton, 1963

The cave squeaker Arthroleptis troglodytes Poynton, 1963 was first collected in 1961/62, and not observed again for 54 years despite several attempts to locate it. We rediscovered this species near the type locality in the Chimanimani mountain range in eastern Zimbabwe. We describe for the first time the call and colour in life, and highlight several morphological and habitat features not previously recorded for this species.     

Immunisation against ovine caseous lymphadenitis: correlation between Corynebacterium pseudotuberculosis toxoid content and protective efficacy in combined clostridial-corynebacterial vaccines

Groups of sheep were dosed with vaccines containing Corynebacterium pseudotuberculosis toxoid combined in varying amounts with 5 clostridial antigens. Resistance of the sheep to infection with C pseudotuberculosis was tested at 1, 6 and 12 months after vaccination by infection with pus from ovine lymph glands actively infected with C pseudotuberculosis. The outcome was assessed 3 months after challenge by slaughter and inspection of the sheep for caseous lymphadenitis lesions. Protection was demonstrated by a significant reduction in the proportion of immunised sheep exhibiting lesions compared with control sheep, and by fewer abscesses in affected immunised sheep than in affected control sheep. A positive correlation was found between amount of C pseudotuberculosis toxoid administered and degree of protection obtained. Chromatographically-purified toxoid induced essentially the same protection, suggesting that anti-toxic immunity is the major factor in protection.     

Über den Einfluß konstanter Temperaturen,relativer Luftfeuchtigkeiten und Licht auf die Frühjahrsentwicklung der Wintereier der Obstbaumspinnmilbe Paratetranychus pilosus Can. et Franz

Zusammenfassung 1. Wintereier vonParatetranychus pilosus Can. et Franz. wurden bei verschiedenen konstanten Temperaturen und relativen Luftfeuchtigkeiten gehalten. Am schnellsten entwickelten sich die Eier bei 24°C.2. Niedere Luftfeuchtigkeiten verzögern die Embryonalentwicklung und erhöhen die Mortalität. Diese war bei 90% relativer Luftfeuchte am geringsten.3. Die Diskrepanz zwischen dem vonListo ermittelten Temperaturoptimum und dem hier mitgeteilten wird mit der Existenz physiologischer Rassen zu erklären versucht.4. Im Dunkeln und UV-Licht gehaltene Wintereier schlüpfen mit erhöhter Mortalität. Es sind im Gegensatz zuHueck keine Anzeichen für eine physiologische Beziehung zwischen dem roten Dotterpigment und der Wellenlänge des Lichtes vorhanden.5. Die Wintereier folgen unter dem Einfluß konstanter Temperaturen, relativer Luftfeuchtigkeiten und Licht denselben Regeln wie Insekteneier.     

A Vegetation Index qualifying pasture edges is related to Ixodes ricinus density and to Babesia divergens seroprevalence in dairy cattle herds

Babesia divergens, transmitted by the tick Ixodes ricinus, is the main agent of bovine piroplasmosis in France. This Apicomplexa often is present in asymptomatic carriers; however, clinical cases are rare. While numerous factors are known to influence tick density, no risk factor of contact with B. divergens has been identified for cattle. Our study aimed to explore whether a Vegetation Index could serve as an indirect indicator of within-herd B. divergens seroprevalence. In February 2007, blood samples were taken from all of the cows in 19 dairy cattle herds in Western France and IFAT serology was performed individually to measure B. divergens seroprevalence. The following spring, I. ricinus nymphs were collected by drag sampling along transects on the vegetation of each farm's pasture perimeters. Tick density was related significantly to a Vegetation Index (V.I., ranging from 1 to 5) that took into account the abundance of trees and bushes on the edge of pastures: most ticks (57%) were found in transects with the highest V.I. (covering 15% of the explored surface in the study area). At the farm level, the proportion of transects presenting I. ricinus nymphs was significantly related to B. divergens seroprevalence: the farms with more than 15% of transects with I. ricinus had a significantly higher risk of high seroprevalence. The proportion of pasture perimeters where the V.I.=5 also was significantly related to B. divergens seroprevalence: the farms where more than 20% of transects had a V.I.=5 had a significantly higher risk of high seroprevalence. Given that the Vegetation Index is a steady indicator of the potential I. ricinus density in the biotope, we recommend that the risk of high B. divergens seroprevalence in cows be evaluated using this tool rather than drag samplings.