A community based land trust (CBLT) model for Saskatchewan agriculture

Non-Peer Reviewe

Study of Two-Proton Pickup Using the (6-Li,8-B) Reaction

This work was supported by National Science Foundation Grants PHY 76-84033A01, PHY 78-22774, and Indiana Universit

Origins and evolution of stomatal development

The fossil record suggests stomata-like pores were present on the surfaces of land plants over 400 million years ago. Whether stomata arose once or whether they arose independently across newly evolving land plant lineages has long been a matter of debate. In Arabidopsis, a genetic toolbox has been identified that tightly controls stomatal development and patterning. This includes the basic helix-loop-helix (bHLH) transcription factors SPEECHLESS (SPCH), MUTE, FAMA, and ICE/SCREAMs (SCRMs), which promote stomatal formation. These factors are regulated via a signaling cascade, which includes mobile EPIDERMAL PATTERNING FACTOR (EPF) peptides to enforce stomatal spacing. Mosses and hornworts, the most ancient extant lineages to possess stomata, possess orthologs of these Arabidopsis (Arabidopsis thaliana) stomatal toolbox genes, and manipulation in the model bryophyte Physcomitrella patens has shown that the bHLH and EPF components are also required for moss stomatal development and patterning. This supports an ancient and tightly conserved genetic origin of stomata. Here, we review recent discoveries and, by interrogating newly available plant genomes, we advance the story of stomatal development and patterning across land plant evolution. Furthermore, we identify potential orthologs of the key toolbox genes in a hornwort, further supporting a single ancient genetic origin of stomata in the ancestor to all stomatous land plants

Origins and evolution of stomatal development

The fossil record suggests stomata-like pores were present on the surfaces of land plants over 400 million years ago. Whether stomata arose once or whether they arose independently across newly evolving land plant lineages has long been a matter of debate. In Arabidopsis, a genetic toolbox has been identified that tightly controls stomatal development and patterning. This includes the basic helix-loop-helix (bHLH) transcription factors SPEECHLESS (SPCH), MUTE, FAMA, and ICE/SCREAMs (SCRMs), which promote stomatal formation. These factors are regulated via a signaling cascade, which includes mobile EPIDERMAL PATTERNING FACTOR (EPF) peptides to enforce stomatal spacing. Mosses and hornworts, the most ancient extant lineages to possess stomata, possess orthologs of these Arabidopsis (Arabidopsis thaliana) stomatal toolbox genes, and manipulation in the model bryophyte Physcomitrella patens has shown that the bHLH and EPF components are also required for moss stomatal development and patterning. This supports an ancient and tightly conserved genetic origin of stomata. Here, we review recent discoveries and, by interrogating newly available plant genomes, we advance the story of stomatal development and patterning across land plant evolution. Furthermore, we identify potential orthologs of the key toolbox genes in a hornwort, further supporting a single ancient genetic origin of stomata in the ancestor to all stomatous land plants

Stomata and sporophytes of the model moss physcomitrium patens

Mosses are an ancient land plant lineage and are therefore important in studying the evolution of plant developmental processes. Here, we describe stomatal development in the model moss species Physcomitrium patens (previously known as Physcomitrella patens) over the duration of sporophyte development. We dissect the molecular mechanisms guiding cell division and fate and highlight how stomatal function might vary under different environmental conditions. In contrast to the asymmetric entry divisions described in Arabidopsis thaliana, moss protodermal cells can enter the stomatal lineage directly by expanding into an oval shaped guard mother cell (GMC). We observed that when two early stage P. patens GMCs form adjacently, a spacing division can occur, leading to separation of the GMCs by an intervening epidermal spacer cell. We investigated whether orthologs of Arabidopsis stomatal development regulators are required for this spacing division. Our results indicated that bHLH transcription factors PpSMF1 and PpSCRM1 are required for GMC formation. Moreover, the ligand and receptor components PpEPF1 and PpTMM are also required for orientating cell divisions and preventing single or clustered early GMCs from developing adjacent to one another. The identification of GMC spacing divisions in P. patens raises the possibility that the ability to space stomatal lineage cells could have evolved before mosses diverged from the ancestral lineage. This would have enabled plants to integrate stomatal development with sporophyte growth and could underpin the adoption of multiple bHLH transcription factors and EPF ligands to more precisely control stomatal patterning in later diverging plant lineages. We also observed that when P. patens sporophyte capsules mature in wet conditions, stomata are typically plugged whereas under drier conditions this is not the case; instead, mucilage drying leads to hollow sub-stomatal cavities. This appears to aid capsule drying and provides further evidence for early land plant stomata contributing to capsule rupture and spore release

Nuclear Structure Studies of Light-Mass Radon Isotopes Using the 209-Bi(6-Li,xnγ) Reactions

This work was supported by National Science Foundation Grant PHY 75-00289 and Indiana Universit

The excretion of biuret in the urine of sheep fed biuret

The articles have been scanned in colour with a HP scanjet 5590; 300dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to final presentation PDF-Format

In-situ measurement of the meniscus at the entry and exit of grease and oil lubricated rolling bearing contacts

The lubricant inlet meniscus in a rolling element bearing acts as a reservoir that feeds the elastohydrodynamic contact, resulting in a sufficiently thick film to avoid wear. A shortening and/or thinning of the inlet meniscus towards the contact centre is an indicator of bearing starvation and impaired lubricant performance. This work introduces an ultrasonic method to measure meniscus dimensions. Using in situ ultrasonic sensors on a full-scale cylindrical roller bearing test rig, we show that ultrasonic waves can cause oil films to resonate, and that the resonant frequency is directly related to the film thickness. Using a benchtop rig we validate the relationship between resonant frequency and film thickness. This allows for the measurement of meniscus thickness and length in situ during bearing operation. Menisci were measured at both the inlet and outlet of rolling bearing line contacts while lubricated with different viscosity oils and grease. All lubricants used showed they could be monitored using this approach. The implication of this paper is that it is possible to measure a critically important lubrication mechanism during operation without major component modifications

The pathological physiology of helminth infestation. lll. Trichostrongylus colubriformis

Trials are described in which the reactions of 11 sheep infested with T. colubriformis and 11 uninfected controls were studied in detail. The main findings in the acute disease were anorexia, retention of ingesta in the rumen and abomasum, diarrhoea, a severe hypo-albuminaemia and death 16 to 17 days after infestation. In the chronic disease there was a progressive decrease in feed intake and loss of body weight. Plasma albumin concentration decreased with a rise in plasma gamma globulin concentration later in the disease. A drop in packed red cell volume, haemoglobin concentration, red cell count, total volume of circulating erythrocytes and plasma inorganic phosphate was noted. There was a decrease in protein, phosphate and possibly selenium uptake leading to emaciation, muscular and myocardial atrophy and degeneration and eventually death.The journals have been scanned in colour with a HP 5590 scanner; 600 dpi. Adobe Acrobat v.11 was used to OCR the text and also for the merging and conversion to the final presentation PDF-format

Rice SUMO protease Overly Tolerant to Salt 1 targets the transcription factor, OsbZIP23 to promote drought tolerance in rice

Conjugation of SUMO (Small Ubiquitin-like Modifier) protein to cellular targets is emerging as a very influential protein modification system. Once covalently bound SUMO conjugation can change the stability or functionality of its cognate target proteins. SUMO protease can rapidly reverse SUMO conjugation making this modification system highly dynamic. A major factor in the variation of SUMO-target function is the balance between the conjugated/de-conjugated forms. The mechanistic role of these regulatory SUMO proteases in mediating stress responses has not been defined in any crops. In this study, we reveal the role of the SUMO protease, OsOTS1 in mediating tolerance to drought in rice. OsOTS1 depleted transgenic plants accumulate more ABA and exhibit more productive agronomic traits during drought whilst OsOTS1 overexpressing lines are drought sensitive but ABA insensitive. Drought and ABA treatment stimulates the degradation of OsOTS1 protein indicating that SUMO conjugation is an important response to drought stress in rice achieved through down-regulation of OTS1/2 activity. We reveal that OsOTS1 SUMO protease directly targets the ABA and drought responsive transcription factor OsbZIP23 for de-SUMOylation affecting its stability. OsOTS-RNAi lines show increased abundance of OsbZIP23 and increased drought responsive gene expression while OsOTS1 overexpressing lines show reduced levels of OsbZIP23 leading to suppressed drought responsive gene expression. Our data reveals a mechanism where rice plants govern ABA dependant drought responsive gene expression by controlling the stability of OsbZIP23 by SUMO conjugation through manipulating specific SUMO protease levels