Fission track ages and ages of deposition of deep-sea microtektites

The Australasian and Ivory Coast deep-sea microtektites have fission track ages of 0.71 and 1.09 million years, respectively. These ages are in good agreement with the ages of deposition of the microtektites determined from paleomagnetic data. Both the fission track ages and ages of deposition of the microtektites agree with the potassium/ argon and fission track ages of tektites from the respective tektite strewn fields.     

Beaver dams,streamflow complexity,and the distribution of a rare minnow,Lepidomeda copei

Freshwater fishes are threatened globally, and often too little is known about threatened species to effectively guide their conservation. Habitat complexity is linked to fish species diversity and persistence, and degraded streams often lack habitat complexity. Beaver Castor spp., in turn, have been used to restore streams and increase habitat complexity. The northern leatherside chub Lepidomeda copei is a rare, small‐bodied, drift‐feeding minnow that has anecdotally been observed to use complex habitats associated with beaver dams in the western United States. To investigate this anecdote, we conducted fish and habitat surveys, the latter focusing on quantifying habitat complexity, in a sub‐basin of the Upper Snake River Basin in the USA. Complementary generalised linear model and path analyses revealed that northern leatherside chub occurred more often at sites with complex streamflows, and streamflows were more complex when beaver dams were present and pools were deeper. Northern leatherside chubs were also more likely to occur when temperatures were warmer, aquatic macrophytes were abundant and stream channels were narrow and deep. The linkage between chubs, complex streamflows and beaver dams needs to be evaluated more broadly to completely understand its role in the rangewide status of the species. However, it does suggests that increased use of beaver reintroductions and dam analogues for stream restoration could be a boon for the northern leatherside chub, but such efforts should be monitored to determine their effectiveness to help adapt beaver‐based restoration approaches to best benefit the species.     

The pharmacokinetics of chloramphenicol in plasma and saliva of dairy cows

In the present study the pharmacokinetics of chloramphenicol were investigated in bovine plasma and saliva. The method of detection of chloramphenicol, a radio-immunoassay, requires only small sample volumes, no further clean-up, and a large number of samples can be processed simultaneously. This enabled the collection of a larger number of samples over a longer period of time than in previous studies. The intention was to obtain a complete pharmacokinetic profile of chloramphenicol, to evaluate it according to common open-compartment models, and to compare it with the results of previous studies. The radio-immunoassay results were confirmed by analysing a number of samples distributed over the concentration range of interest by a gas-chromatographic method with electron-capture detection. The suitability of saliva was evaluated as a possible means of monitoring compliance with the ban on chloramphenicol in the Federal Republic of Germany in milk-producing animals.     

The humoral and cellular immune response of sheep against Borna disease virus in endemic and non-endemic areas

Borna Disease (BD) is a mostly fatal disease of horses and sheep endemic in central Europe. Antibodies to Borna disease virus (BDV) have been described in sheep and other species living in BD non-endemic areas. Meaningful clinical BDV serology is hampered by difficulties in defining serological cut-offs, which require the investigation of populations from endemic areas. Here we studied BD serology in sheep from endemic and non-endemic areas of similar geography in Switzerland. Antibodies to BDV antigens were detected by ELISA and indirect immunofluorescence analysis (IFA) only in sera from 3 of 6 sheep with autopsy confirmed BD. One serum was positive by IFA but not by ELISA, while 2 sera were negative in both assays, indicating that not all diseased animals develop BDV specific antibodies. Six % of clinically healthy animals (6/106) from an endemic area and 2% from a non-endemic area (4/192) had serum antibody to either BDV p40 or p24 as detected by ELISA. None of the animals showed a cellular immune response to BDV p40. In some healthy sheep from the endemic area, serum antibody titers to BDV p24 antigen remained elevated over several months without onset of disease symptoms. Infections with either BDV or related viruses may thus occur at low frequency in sheep from non-endemic areas leading to the production of antibodies to BDV antigens. We further propose viral strain differences or environmental factor(s) may determine the clinical outcome.     

Subolesin/akirin orthologs from Ornithodoros spp. soft ticks: cloning, RNAi gene silencing and protective effect of the recombinant proteins

Subolesin/akirin is a well characterized protective antigen highly conserved across vector species and thus potentially useful for the development of a broad-spectrum vaccine for the control of arthropod infestations including hard ticks, mosquitoes, sand flies and the poultry red mite Dermanyssus gallinae. Soft ticks could be also targeted by this vaccine if proved that the soft tick subolesin orthologs are conserved and induce protective immune responses too. However, to date no soft tick subolesin orthologs have been fully characterized nor tested as recombinant antigens in vaccination trials. The objectives of the present work were to clone and characterize the subolesin orthologs from two important vector species of soft ticks as Ornithodoros erraticus and O. moubata, to evaluate the effect of subolesin gene silencing by RNAi, and to test the protective value of the recombinant antigens in vaccination trials. The obtained results demonstrate that both soft tick subolesins are highly conserved showing more than 69% and 74% identity with those of hard ticks in their nucleotide and amino acid sequences, respectively. Additionally, we demonstrate that both soft ticks possess fully operative RNAi machinery, and that subolesin gene silencing by dsRNA injection inhibits oviposition indicating the involvement of subolesin in tick reproduction. Finally, vaccination with the recombinant soft tick subolesins induced a partial protective effect resulting in the reduction of the oviposition rate. These preliminary results encourage further studies on the use of recombinant subolesins as vaccines for the control of soft tick infestations, either alone or in combination with other specific molecules.     

Comment on "Nonreciprocal light propagation in a silicon photonic circuit"

We show that the structure demonstrated by Feng et al. (Reports, 5 August 2011, p. 729) cannot enable optical isolation because it possesses a symmetric scattering matrix. Moreover, one cannot construct an optical isolator by incorporating this structure into any system as long as the system is linear and time-independent and is described by materials with a scalar dielectric function.     

Multilineage potential of adult human mesenchymal stem cells

Human mesenchymal stem cells are thought to be multipotent cells, which are present in adult marrow, that can replicate as undifferentiated cells and that have the potential to differentiate to lineages of mesenchymal tissues, including bone, cartilage, fat, tendon, muscle, and marrow stroma. Cells that have the characteristics of human mesenchymal stem cells were isolated from marrow aspirates of volunteer donors. These cells displayed a stable phenotype and remained as a monolayer in vitro. These adult stem cells could be induced to differentiate exclusively into the adipocytic, chondrocytic, or osteocytic lineages. Individual stem cells were identified that, when expanded to colonies, retained their multilineage potential.     

Germination of Chromolaena odorata (L.) K. & R. achenes: effect of temperature, imbibition and light

Chromolaena odorata (L.) K. & R. (= Eupatorium odoratum L.) has invaded large areas of the coastal belt of Natal province in South Africa. Propagation is predominantly by means of windborne achenes. The germination of these achenes was investigated. Of the temperatures tested, alternating 15/30°C was optimal for germination. These achenes are positively photoblastic and an imbibition period prior to exposure was required to sensitize the achenes to light. The promotive effect of red light on the germination of imbibed achenes could be reversed by subsequent exposure to far-red light while the inhibitory effect of far-red light could be nullified by a subsequent red light treatment. This is typical of a phytochromemediated germination response. Germination d'akènes de Chromolaena odorata (L.) K. & R.: effets de la température, de l'imbibition el de la lumière Chromolaena odorata (L.) K. & R. (= Eupatorium odoratum L.) a envahi de grandes superficies dans le littoral de la province de Natal en Afrique du Sud. La plante se répand surtout par moyen d'akènes portés par le vent. La germination de ces akènes a fait l'objet d'une étude. Parmi les températures essayées, 15/30°C s'est révélée optimale pour la germination. Les akènes font preuve d'une photoblasticité positive et pour les sensibiliser à la lumière, il leur faut une période d'imbibition avant de les y exposer. La promotion de germination provoquée par la lumière rouge chez les akènes imbibés a pu etre inversée par une exposition ultérieure à la lumière extrême-rouge (700 à 750 nm) tandis que l'effet inhibiteur de celle-ci s'est trouvé annulé par un traitement ultérieur à la lumière rouge. Cette réaction est caractéristique d'une germination réglée par le phytochrome. Die Keimung von Achaenen von Chromolaena odorata (L.) K. & R.: der Einfluss von Temperatur, Quellung und Licht. Chromolaena odorata (L.) K. & R. (= Eupatorium odoratumL.) hat sich auf grossen Flächen des Küstengürtels der Provinz Natal (Südafrika) ausgebreitet. Durch den Wind verbreitete Achaenen sind hauptsächlich für die Vermehrung verantwortlich. Thema der vorliegenden Untersuchung war die Keimung dieser Achaenen. Alternierende Temperaturen von 15° und 30°C waren optimal für die Keimung. Die Achaenen waren positiv photoblastisch; eine Quellungsperiode war notwendig um die Achaenen für die Lichtreaktion zu sensibilisieren. Der die Keimung vorgequollener Achaenen fördernde Einfluss von Rotlicht konnte durch eine nachfolgende‘Fern-Rot'-Exposition rückgängig gemacht werden. Hingegen wurde der Hemmungseffekt von ‘Fern-Rot’ durch eine darauffolgende Rotlicht-Exposition aufgehoben. Dieser Befund ist charakteristisch für eine phytochromregulierte Samenkeimung.