Bill Palmer

High invertase activity in tomato reproductive organs correlates with enhanced sucrose import into, and heat tolerance of, young fruit

Heat stress can cause severe crop yield losses by impairing reproductive development. However, the underlying mechanisms are poorly understood. We examined patterns of carbon allocation and activities of sucrose cleavage enzymes in heat-tolerant (HT) and -sensitive (HS) tomato (Solanum lycopersicum L.) lines subjected to normal (control) and heat stress temperatures. At the control temperature of 25/20 °C (day/night) the HT line exhibited higher cell wall invertase (CWIN) activity in flowers and young fruits and partitioned more sucrose to fruits but less to vegetative tissues as compared to the HS line, independent of leaf photosynthetic capacity. Upon 2-, 4-, or 24-h exposure to day or night temperatures of 5 °C or more above 25/20 °C, cell wall (CWIN) and vacuolar invertases (VIN), but not sucrose synthase (SuSy), activities in young fruit of the HT line were significantly higher than those of the HS line. The HT line had a higher level of transcript of a CWIN gene, Lin7, in 5-day fruit than the HS line under control and heat stress temperatures. Interestingly, heat induced transcription of an invertase inhibitor gene, INVINH1, but reduced its protein abundance. Transcript levels of LePLDa1, encoding phospholipase D, which degrades cell membranes, was less in the HT line than in the HS line after exposure to heat stress. The data indicate that high invertase activity of, and increased sucrose import into, young tomato fruit could contribute to their heat tolerance through increasing sink strength and sugar signalling activities, possibly regulating a programmed cell death pathway.

PEA-CLARITY: 3D molecular imaging of whole plant organs.

Here we report the adaptation of the CLARITY technique to plant tissues with addition of enzymatic degradation to improve optical clearing and facilitate antibody probe penetration. Plant-Enzyme-Assisted (PEA)-CLARITY, has allowed deep optical visualisation of stains, expressed fluorescent proteins and IgG-antibodies in Tobacco and Arabidopsis leaves. Enzyme treatment enabled penetration of antibodies into whole tissues without the need for any sectioning of the material, thus facilitating protein localisation of intact tissue in 3D whilst retaining cellular structure.

A developing Setaria viridis internode: an experimental system for the study of biomass generation in a C4 model species

BackgroundRecently, there has been interest in establishing a monocot C4 model species with a small genome, short lifecycle, and capacity for genetic transformation. Setaria viridis has been adopted to fill this role, since reports of Agrobacterium-mediated transformation in 2010, and sequencing of its genome in 2012. To date, S. viridis has primarily been used to further our understanding of C4 photosynthesis, but is also an ideal system for the study of biomass crops, which are almost exclusively C4 panicoid grasses. Biogenesis of stem tissue, its cell wall composition, and soluble sugar content are important determinants of bioenergy crop yields. Here we show that a developing S. viridis internode is a valuable experimental system for gene discovery in relation to these important bioenergy feedstock traits.ResultsThe rate of maximal stem biomass accumulation in S. viridis A10 under long day growth was at the half-head emergence developmental stage. At this stage of development, internode 5 (of 7) was found to be rapidly expanding with an active meristem, a zone of cell expansion (primary cell walls), a transitional zone where cell expansion ceased and secondary cell wall deposition was initiated, and a mature zone that was actively accumulating soluble sugars. A simple method for identifying these zones was established allowing rapid dissection and snap-freezing for RNAseq analysis. A transcriptome profile was generated for each zone showing a transition from cell division and nucleic acid synthesis/processing in the meristem, to metabolism, energy synthesis, and primary cell wall synthesis in the cell expansion zone, to secondary cell wall synthesis in the transitional zone, to sugar transport, and photosynthesis in the mature zone.ConclusionThe identification of these zones has provided a valuable experimental system for investigating key bioenergy traits, including meristematic activity, cell wall biosynthesis, and soluble sugar accumulation, in a C4 panicoid grass that has genetic resources, a short life cycle, and small stature allowing controlled experimental conditions in growth cabinets. Here we have presented a comprehensive map of gene expression and metabolites in this experimental system to facilitate gene discovery and controlled hypothesis testing for bioenergy research in S. viridis.

Clause order and information structure in Cheke Holo

Cheke Holo (Northwest Solomonic, Solomon Islands) displays considerable clause order variation, with SVO, OVS, VSO, and VOS all attested. In addition, arguments are frequently not overtly expressed, while some arguments may be marked with the preposed particle si. This paper investigates these issues in terms of information structure by examining each in its discourse context. It concludes that the pragmatically neutral order in Cheke Holo is VSO; that a single preverbal topic position exists, accounting for SVO and OVS; and that focused arguments are located in clause-final position, accounting for VOS. It finds that continued topics are always expressed by topic-drop (that is, elision), and that preverbal position is reserved for contrastive topics and switch topics, although in certain specific contexts, switch topics may instead be dropped. The paper concludes that preposed si is confined to main clauses and is a focus marker for arguments and adjuncts in clause-final position, but that another particle si, with a variant sini, occurs following, not preceding, a sentence-initial focused constituent that can range in size from an argument to an entire clause. On the basis of the analysis presented, Cheke Holo demonstrates that focused arguments need not be new information, as often assumed, but merely need to be unpredictable in the discourse context, allowing for discourse-given or context-given arguments in contrastive focus.

Subject-indexing and possessive morphology in Northwest Solomonic

Abstract Most Northwest Solomonic (NWS) languages employ possessor-indexing or former possessor-indexing morphology to index subject on verbs. Although the phenomenon of dependent-marking languages using cognate morphology to case mark possessors and subjects is well known, head marking in the form of subject agreement using possessor-indexing morphology of the kind seen in NWS is less well understood. Moreover, most instances of cognate possessor-indexing and subject-indexing morphology typically result from independent pronouns in parallel processes of grammaticalization. In NWS the subject-indexing function arose from a well-established preexisting possessor-indexing function, demonstrating a diachronic functional shift from nominal marking to verb marking. Moreover, in several NWS languages two possessor-indexing hosts encoding distinct semantic categories of possession occur in verbal constructions marking different kinds of events, raising the question of how a semantic distinction between kinds of entities can be meaningfully applied to categories of events. This article surveys functional and formal characteristics of synchronic “possessive” subject-indexing morphology across NWS, and proposes an originating nominalization construction in Proto-NWS from which the synchronic phenomena arose. It reappraises Rosss (The development of the verb phrase in the Oceanic languages of the Bougainville region, Pacific Linguistics, 1982) hypothesis on the origin of the phenomenon, and the hypothesis that two distinct clause structures are involved in the presence or absence of this morphology. It then investigates several key problems not previously addressed, including why the order of subject-indexing morphology and verb it accompanies is the reverse of the order of possessor-indexing morphology and noun in nominal constructions, and how distinct nominal categories of possession encoded by the two possessor-indexing hosts could be reinterpreted as a verbal distinction of event type.

Imperfective Aspect and the Interplay of Aspect, Tense, and Modality in Torau

Torau displays a highly complex system of aspect, tense, and modal marking. One of the most complex elements of this system is the marking of imperfective aspect. Imperfective in Torau is marked by a construction employing a choice of two overt imperfective markers and the possible presence of reduplication. The range of imperfective semantics encoded by this construction varies widely, encompassing progressive, habitual, persistive, and progressive inchoative or inceptive. Which reading is given depends not only on the choice of imperfective marker and the presence or absence of reduplication, but on a complex interplay of these factors with other aspectual, modal, or tense marking, and the aspectual semantics of the verb itself. This paper teases apart each of these highly interdependent factors to determine the independent functional characteristics of each imperfective marker and of reduplication.

Voiceless sonorants—phonemes or underlying clusters?*

This paper examines the phenomenon of voiceless sonorants in Kokota (Oceanic, Solomon Islands). The phonemic status of these phones is examined in terms of the question—are they underlyingly phonemes, or the result of the synchronic surface coalescence of underlying /h/ plus sonorant clusters? The relevant data from Kokota are presented, then two alternative models are briefly described—underlying voiceless sonorant phonemes in Iaai, and the surface coalescence of CC sequences in Lenakel.1 Evidence from within Kokota is then examined in an attempt to determine which model Kokota best fits. The paper concludes that these Kokota phones represent underlying voiceless sonorant phonemes, giving the language a consonant phoneme inventory in which every voiced phoneme has a voiceless counterpart.

Advantages and Limitations of Current Imaging Techniques for Characterizing Liposome Morphology

There are currently a number of imaging techniques available for evaluating the morphology of liposomes and other nanoparticles, with each having its own advantages and disadvantages that should be considered when interpreting data. Controlling and validating the morphology of nanoparticles is of key importance for the effective clinical translation of liposomal formulations. There are a number of physical characteristics of liposomes that determine their in vivo behavior, including size, surface characteristics, lamellarity, and homogeneity. Despite the great importance of the morphology of nanoparticles, it is generally not well-characterized and is difficult to control. Appropriate imaging techniques provide important details regarding the morphological characteristics of nanoparticles, and should be used in conjunction with other methods to assess physicochemical parameters. In this review, we will discuss the advantages and limitations of available imaging techniques used to evaluate liposomal formulations.

3D Clearing and Molecular Labeling in Plant Tissues

Plant histology and imaging traditionally involve the transformation of tissues into thin sections to minimize light scatter in opaque material, allowing optical clarity and high-resolution microscopy. Recently, new techniques in 3D tissue clearing, including PEA-CLARITY, have been developed to minimize light scatter within intact, whole samples. These techniques can achieve equivalent microscopic resolution to that of thin section imaging with the added benefit of maintaining the original 3D structure and position of biomolecules of interest. Furthermore, PEA-CLARITY is compatible with standard stains and immunohistochemistry, allowing molecular interrogation of intact, 3D tissues. This chapter outlines the current methods available for 3D histology in plants and details the materials, equipment, reagents, and procedure for the PEA-CLARITY technique.

Diversity in Spatial Language Within Communities: The Interplay of Culture, Language and Landscape in Representations of Space (Short Paper).

Significant diversity exists in the way languages structure spatial reference, and this has been shown to correlate with diversity in non-linguistic spatial behaviour. However, most research in spatial language has focused on diversity between languages: on which spatial referential strategies are represented in the grammar, and to a lesser extent which of these strategies are preferred overall in a given language. However, comparing languages as a whole and treating each language as a single data point provides a very partial picture of linguistic spatial behaviour, failing to recognise the very significant diversity that exists within languages, a largely under-investigated but now emerging field of research. This paper focuses on language-internal diversity, and on the central role of a range of sociocultural and demographic factors that intervene in the relationship between humans, languages, and the physical environments in which communities live.