Identification of a small RNA containing the trypanosome spliced leader: a donor of shared 5' sequences of trypanosomatid mRNAs?

The 35 nucleotide spliced leader (SL) sequence is found on the 5' end of numerous trypanosome mRNAs, yet the tandemly organized reiteration units encoding this leader are not detectably linked to any of these structural genes. Here we report the presence of a class of discrete small SL RNA molecules that are derived from the genomic SL reiteration units of Trypanosoma brucei, Trypanosoma cruzi, and Leptomonas collosoma. These small SL RNAs are 135, 105, and 95 nucleotides, respectively, and contain a 5'-terminal SL or SL-like sequence. S1 nuclease analyses demonstrate that these small SL RNAs are transcribed from continuous sequence within the respective SL reiteration units. With the exception of the SL sequence and a concensus donor splice site immediately following it, these small RNAs are not well conserved. We suggest that the small SL RNAs may function as a donor of the SL sequence in an intermolecular process that places the SL at the 5' terminus of many trypanosomatid mRNAs

Body fluid volume and electrolyte derangements in fasting semiannual report no. 1, dec. 1, 1964 - mar. 31, 1965

Electrolyte balance studies on rats maintained in metabolism cages - body fluid volume and electrolyte derangements by fasting in col

Functional analysis of B and C class floral organ genes in spinach demonstrates their role in sexual dimorphism

<p>Abstract</p> <p>Background</p> <p>Evolution of unisexual flowers entails one of the most extreme changes in plant development. Cultivated spinach, <it>Spinacia oleracea </it>L., is uniquely suited for the study of unisexual flower development as it is dioecious and it achieves unisexually by the absence of organ development, rather than by organ abortion or suppression. Male staminate flowers lack fourth whorl primordia and female pistillate flowers lack third whorl primordia. Based on theoretical considerations, early inflorescence or floral organ identity genes would likely be directly involved in sex-determination in those species in which organ initiation rather than organ maturation is regulated. In this study, we tested the hypothesis that sexual dimorphism occurs through the regulation of B class floral organ gene expression by experimentally knocking down gene expression by viral induced gene silencing.</p> <p>Results</p> <p>Suppression of B class genes in spinach resulted in the expected homeotic transformation of stamens into carpels but also affected the number of perianth parts and the presence of fourth whorl. Phenotypically normal female flowers developed on <it>SpPI</it>-silenced male plants. Suppression of the spinach C class floral organ identity gene, <it>SpAG</it>, resulted in loss of reproductive organ identity, and indeterminate flowers, but did not result in additional sex-specific characteristics or structures. Analysis of the genomic sequences of both <it>SpAP3 </it>and <it>SpPI </it>did not reveal any allelic differences between males and females.</p> <p>Conclusion</p> <p>Sexual dimorphism in spinach is not the result of homeotic transformation of established organs, but rather is the result of differential initiation and development of the third and fourth whorl primordia. <it>SpAG </it>is inferred to have organ identity and meristem termination functions similar to other angiosperm C class genes. In contrast, while <it>SpPI </it>and <it>SpAP3 </it>resemble other angiosperms in their essential functions in establishing stamen identity, they also appear to have an additional function in regulating organ number and identity outside of the third whorl. We present a model for the evolution of dioecy in spinach based on the regulation of B class expression.</p

How can we confidently judge the extent to which student voice in higher education has been genuinely amplified? A proposal for a new evaluation framework

This article aims to contribute to the development of frameworks for evaluating student voice projects in higher education by offering a critically evaluative account of two student voice projects. Although both projects had been underpinned by the principles of participatory (inclusive) research, one appeared to be more successful than the other in engaging students in a productive or meaningful way. In order to confirm and explain these perceived differences, this paper draws on both student voice and participatory research literature to identify two potentially useful evaluation criteria: reach and fitness for purpose. These criteria are applied to three project factors: aims and assumptions, processes and outcomes to produce an amplitude framework for evaluating student voice in higher education. It is argued that this framework has the potential to enable a rich account of the relative successes and failures of student voice initiatives in higher education

The effect of hydrogen evolution from HUP field pea nodules on nitrous oxide production

Non-Peer Reviewe

Does hydrogen evolution from HUP- field pea nodules stimulate nitrous oxide production?

Non-Peer Reviewe

Development of a gene silencing DNA vector derived from a broad host range geminivirus

<p>Abstract</p> <p>Background</p> <p>Gene silencing is proving to be a powerful tool for genetic, developmental, and physiological analyses. The use of viral induced gene silencing (VIGS) offers advantages to transgenic approaches as it can be potentially applied to non-model systems for which transgenic techniques are not readily available. However, many VIGS vectors are derived from Gemini viruses that have limited host ranges. We present a new, unipartite vector that is derived from a curtovirus that has a broad host range and will be amenable to use in many non-model systems.</p> <p>Results</p> <p>The construction of a gene silencing vector derived from the geminivirus <it>Beet curly top virus </it>(BCTV), named pWSRi, is reported. Two versions of the vector have been developed to allow application by biolistic techniques or by agro-infiltration. We demonstrate its ability to silence nuclear genes including ribulose bisphosphate carboxylase small subunit (<it>rbcS</it>), <it>transketolase</it>, the sulfur allele of magnesium chelatase (<it>ChlI</it>), and two homeotic transcription factors in spinach or tomato by generating gene-specific knock-down phenotypes. Onset of phenotypes occurred 3 to 12 weeks post-inoculation, depending on the target gene, in organs that developed after the application. The vector lacks movement genes and we found no evidence for significant spread from the site of inoculation. However, viral amplification in inoculated tissue was detected and is necessary for systemic silencing, suggesting that signals generated from active viral replicons are efficiently transported within the plant.</p> <p>Conclusion</p> <p>The unique properties of the pWSRi vector, the ability to silence genes in meristem tissue, the separation of virus and silencing phenotypes, and the broad natural host range of BCTV, suggest that it will have wide utility.</p