Comparison of two histological techniques for age determination in small cetaceans

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Single-stranded DNA Plant Pathogens in Eilat

An international conference on 's'sInter- and Intracellular Dynamics of ssDNA Plant Pathogens: Implications for Improving Resistance'' was sponsored by the United States-Israel Binational Agricultural Research and Deveoplment Fund (BARD) and organized in Eilat, Israel in November 2005. The topic of this meeting was single-stranded plant pathogens, their inter- as well as intra-cellular dynamics and their implications for improving resistance. Most of the talks concentrated on new and very new findings on principles of virus and bacterium-host interactions, studies that no doubt will lead eventually to the establishment of plants resistant to viral and bacterial infection

Where were they from? Modelling the source stock of dolphins stranded after the Deepwater Horizon oil spill using genetic and stable isotope data

Understanding the source stock of common bottlenose dolphins Tursiops truncatus that stranded in the northern Gulf of Mexico subsequent to the Deepwater Horizon oil spill was essential to accurately quantify injury and apportion individuals to the appropriate stock. The aim of this study, part of the Natural Resource Damage Assessment (NRDA), was to estimate the proportion of the 932 recorded strandings between May 2010 and June 2014 that came from coastal versus bay, sound and estuary (BSE) stocks. Four sources of relevant information were available on overlapping subsets totaling 336 (39%) of the strandings: genetic stock assignment, stable isotope ratios, photo-ID and individual genetic-ID. We developed a hierarchical Bayesian model for combining these sources that weighted each data source for each stranding according to a measure of estimated precision: the effective sample size (ESS). The photo- and genetic-ID data were limited and considered to potentially introduce biases, so these data sources were excluded from analyses used in the NRDA. Estimates were calculated separately in 3 regions: East (of the Mississippi outflow), West (of the Mississippi outflow through Vermilion Bay, Louisiana) and Western Louisiana (west of Vermilion Bay to the Texas-Louisiana border); the estimated proportions of coastal strandings were, respectively 0.215 (95% CI: 0.169-0.263), 0.016 (0.036-0.099) and 0.622 (0.487-0.803). This method represents a general approach for integrating multiple sources of information that have differing uncertainties.Publisher PDFPeer reviewe

Arbeitszeitflexibilisierung als Beschäftigungspolitisches Instrument - Wirkungen und Grenzen Neuer Arbeitszeitpolitik

"Konzepte einer 'Neuen Arbeitszeitpolitik' treten mit dem doppelten Anspruch auf, durch eine Individualisierung von Arbeitszeitregelungen arbeitsmarktpolitische Probleme lösen und darüber hinaus zur Humanisierung der Arbeit beitragen zu können. Selektivität und Realisierungschancen flexibler Arbeitszeitregelungen wurden bislang hauptsächlich unter technologischen Gesichtspunkten diskutiert. Demgegenüber verfolgt dieser Beitrag die Absicht, den sozialen und institutionellen Verhältnissen Rechnung zu tragen, die im Zuge einer Arbeitszeitflexibilisierung wirksam sind. Zu diesem Zweck wird zunächst eine qualifikations- und organisationssoziologische Perspektive gewählt, die es erlaubt, zu begründen, in welchem Verhältnis Einsatz und Nutzung von Arbeitskräften mit den betrieblichen Organisationserfordernissen stehen. Daran anknüpfend wird gezeigt, wie sich die betriebliche Nutzung von Arbeitskräften auf die Arbeitszeitstruktur auswirkt. Es lassen sich zwei Typen herauskristallisieren, die in einem Entsprechungsverhältnis zur betrieblichen Hierarchie stehen: Im unteren Statusbereich dominieren starre Zeitnormierungen, die einen kontorllierenden Zugriff auf die Arbeitsvorgänge ermöglichen. Vornehmlich im oberen Bereich der Betriebshierarchie sind flexible, selbstbestimmte Muster der Zeitverwendung verbreitet, die mit der Loyalität und Identifikation der hier Beschäftigten mit dem Organisationsziel korrespondieren. Wir interpretieren diesen Befund als betrieblich-organisatorische Formen der Lösung arbeitswirtschaftlicher Probleme, nämlich als Strategien der Externalisierung des Nutzungsrisikos von Arbeitsvermögen im unteren Statusbereich und dessen Internalisierung im oberen Bereich. Im darauffolgenden Schritt diskutieren wir einige Varianten der Arbeitszeitflexibilisierung auf ihre Ausformung hin, die sie aufgrund dieser arbeitswirtschaftlicher Strategien erfahren. Ergebnis dieser Diskussion ist die Wahrscheinlichkeit einer stark selektiven Wirkung der Arbeitszeitflexibilisierung. Diesen kontraintentionalen Effekt erwarten wir primär aufgrund der Zuordnung vornehmlich chronologisch flexibler Arbeitszeitvarianten zu höheren Statuspositionen und chronometrische Varianten zum Bereich restriktiver, konjunkturempfindlicher Arbeitsplätze. Daraus folgt ferner eine in der zeitlichen Dimension stärker als bisher wirksame Zuordnung bestimmter Arbeitskräftegruppen zu den betriebsinternen bzw. zu den überbetrieblichen Arbeitsmärkten. Darüber hinaus erwarten wir primär in den unteren Statusgruppen neben einem Schutzverlust eine Verdichtung der Arbeit. Diese negativen Folgelasten lassen sich um so schwieriger abbauen, als mit der Verbreitung der Arbeitszeitflexibilisierung auch die Individualisierung von Arbeitszeitvereinbarungen verbunden ist. Die Verlagerung von Arbeitszeitregelungen von der tariflichen auf die betriebliche Ebene macht eine staatliche und/oder gewerkschaftliche Schutzpolitik unter den gegebenen institutionellen Voraussetzungen der Interessenvertretung abhängig Beschäftigter nahezu unmöglich. Sollen die Vorzüge von flexiblen Arbeitszeitregelungen daher nicht vollständig preisgegeben werden, bedarf es neuer Formen der staatlichen, tariflichen und innerbetrieblichen Konfliktregelung in diesem Betrieb."Arbeitszeitpolitik, Arbeitszeitflexibilität, Beschäftigung, Betrieb - Organisation

Plant ribosome shunting in vitro

It has been proposed that cauliflower mosaic virus 35S RNA with its 600 nt long leader uses an unusual translation process (the translational shunt). A wheat germ in vitro translation assay was used to improve the study of this mechanism. Deletions, the introduction of stable stem-loop structures, and the inhibitory effect of antisense oligonucleotides on gene expression were used to determine the roles of various parts of the leader. It was found that the 5′- and 3′-ends of the leader are absolutely required for translation whereas the middle part is apparently dispensable. These results confirm the data already reported from transient expression experiments with protoplasts. However, the in vitro data suggest in contrast to protoplast experiments that only two relatively short regions at both ends, ∼100 nt each, are required. The in vitro system provides tools for further studying the shunt model at the molecular level and for examining the involvement of proteins in this mechanism. Shunting was also found to occur with the rice tungro bacilliform virus leader. As wheat is neither a host plant of cauliflower mosaic virus nor rice tungro bacilliform virus, the shunt seems to be host independent, a finding that deviates from earlier studies in protoplast

Transgenic cassava resistance to African cassava mosaic virus is enhanced by viral DNA-A bidirectional promoter-derived siRNAs

Expression of double-stranded RNA (dsRNA) homologous to virus sequences can effectively interfere with RNA virus infection in plant cells by triggering RNA silencing. Here we applied this approach against a DNA virus, African cassava mosaic virus (ACMV), in its natural host cassava. Transgenic cassava plants were developed to express small interfering RNAs (siRNA) from a CaMV 35S promoter-controlled, intron-containing dsRNA cognate to the common region-containing bidirectional promoter of ACMV DNA-A. In two of three independent transgenic lines, accelerated plant recovery from ACMV-NOg infection was observed, which correlates with the presence of transgene-derived siRNAs 21-24nt in length. Overall, cassava mosaic disease symptoms were dramatically attenuated in these two lines and less viral DNA accumulation was detected in their leaves than in those of wild-type plants. In a transient replication assay using leaf disks from the two transgenic lines, strongly reduced accumulation of viral single-stranded DNA was observed. Our study suggests that a natural RNA silencing mechanism targeting DNA viruses through production of virus-derived siRNAs is turned on earlier and more efficiently in transgenic plants expressing dsRNA cognate to the viral promoter and common regio

Upstream and downstream sequence elements determine the specificity of the rice tungro bacilliform virus promoter and influence RNA production after transcription initiation

The contribution of sequences upstream and downstream of the transcription start site to the strength and specificity of the promoter of rice tungro bacilliform virus was analysed in transgenic rice plants. The promoter is strongly stimulated by downstream sequences which include an intron and is active in all vascular and epidermal cells. Expression in the vascular tissue requires a promoter element located between −100 and −164 to which protein(s) from rice nuclear extracts bind. Elimination of this region leads to specificity for the epidermis. Due to the presence of a polyadenylation signal in the intron, short-stop RNA is produced from the promoter in addition to full-length primary transcript and its spliced derivatives. The ratio between short-stop RNA and full-length or spliced RNA is determined by upstream promoter sequences, suggesting the assembly of RNA polymerase complexes with different processivity on this promote

Massive production of small RNAs from a non-coding region of Cauliflower mosaic virus in plant defense and viral counter-defense

To successfully infect plants, viruses must counteract small RNA-based host defense responses. During infection of Arabidopsis, Cauliflower mosaic pararetrovirus (CaMV) is transcribed into pregenomic 35S and subgenomic 19S RNAs. The 35S RNA is both reverse transcribed and also used as an mRNA with highly structured 600 nt leader. We found that this leader region is transcribed into long sense- and antisense-RNAs and spawns a massive quantity of 21, 22 and 24 nt viral small RNAs (vsRNAs), comparable to the entire complement of host-encoded small-interfering RNAs and microRNAs. Leader-derived vsRNAs were detected bound to the Argonaute 1 (AGO1) effector protein, unlike vsRNAs from other viral regions. Only negligible amounts of leader-derived vsRNAs were bound to AGO4. Genetic evidence showed that all four Dicer-like (DCL) proteins mediate vsRNA biogenesis, whereas the RNA polymerases Pol IV, Pol V, RDR1, RDR2 and RDR6 are not required for this process. Surprisingly, CaMV titers were not increased in dcl1/2/3/4 quadruple mutants that accumulate only residual amounts of vsRNAs. Ectopic expression of CaMV leader vsRNAs from an attenuated geminivirus led to increased accumulation of this chimeric virus. Thus, massive production of leader-derived vsRNAs does not restrict viral replication but may serve as a decoy diverting the silencing machinery from viral promoter and coding region

Cestrum yellow leaf curling virus (CmYLCV) promoter: a new strong constitutive promoter for heterologous gene expression in a wide variety of crops

Appropriately regulated gene expression requires a suitable promoter. A number of promoters have been isolated and shown to be functional in plants, but only a few of them activate transcription of transgenes at high levels constitutively. We report here the cloning and characterization of a novel, constitutively expressed promoter isolated from Cestrum yellow leaf curling virus (CmYLCV), a double-stranded DNA plant pararetrovirus belonging to the Caulimoviridae family. The CmYLCV promoter is highly active in callus, meristems and vegetative and reproductive tissues in Arabidopsis thaliana, Nicotiana tabacum, Lycopersicon esculentum,Zea mays and Oryza sativa. Furthermore, the level of expression is comparable to, or higher than, that from the CaMV 35S, the 'ssuper-promoter' or the maize ubiquitin 1 promoters, three frequently used promoters in agricultural biotechnology. The heritable, strong and constitutive activity in both monocotyledonous and dicotyledonous plants, combined with the extremely narrow CmYLCV host range, makes the CmYLCV promoter an attractive tool for regulating transgene expression in a wide variety of plant specie