The structural components of the Azotobacter vinelandii iron-only nitrogenase, AnfDKG, form a protein complex within the plant mitochondrial matrix

A long-held goal of synthetic biology has been the transfer of a bacterial nitrogen-fixation pathway into plants to reduce the use of chemical fertiliser on crops such as rice, wheat and maize. There are three classes of bacterial nitrogenase, named after their metal requirements, containing either a MoFe-, VFe- or FeFe-cofactor, that converts N₂ gas to ammonia. Relative to the Mo-nitrogenase the Fe-nitrogenase is not as efficient for catalysis but has less complex genetic and metallocluster requirements, features that may be preferable for engineering into crops. Here we report the successful targeting of bacterial Fe-nitrogenase proteins, AnfD, AnfK, AnfG and AnfH, to plant mitochondria. When expressed as a single protein AnfD was mostly insoluble in plant mitochondria, but coexpression of AnfD with AnfK improved its solubility. Using affinity-based purification of mitochondrially expressed AnfK or AnfG we were able to demonstrate a strong interaction of AnfD with AnfK and a weaker interaction of AnfG with AnfDK. This work establishes that the structural components of the Fe-nitrogenase can be engineered into plant mitochondria and form a complex, which will be a requirement for function. This report outlines the first use of Fe-nitrogenase proteins within a plant as a preliminary step towards engineering an alternative nitrogenase into crops.

Insights into Nitrogenase Bioelectrocatalysis for Green Ammonia Production

There is a growing interest in using ammonia as a liquid carrier of hydrogen for energy applications. Currently, ammonia is produced industrially by the Haber-Bosch process, which requires high temperature and high pressure. In contrast, bacteria have naturally evolved an enzyme known as nitrogenase, that is capable of producing ammonia and hydrogen at ambient temperature and pressure. Therefore, nitrogenases are attractive as a potentially more efficient means to produce ammonia via harnessing the unique properties of this enzyme. In recent years, exciting progress has been made in bioelectrocatalysis using nitrogenases to produce ammonia. Here, the prospects for developing biological ammonia production are outlined, key advances in bioelectrocatalysis by nitrogenases are highlighted, and possible solutions to the obstacles faced in realising this goal are discussed.

Seed-specific RNAi in safflower generates a superhigh oleic oil with extended oxidative stability

Vegetable oils extracted from oilseeds are an important component of foods, but are also used in a range of high value oleochemical applications. Despite being biodegradable, nontoxic and renewable current plant oils suffer from the presence of residual polyunsaturated fatty acids that are prone to free radical formation that limit their oxidative stability, and consequently shelf life and functionality. Many decades of plant breeding have been successful in raising the oleic content to ~90%, but have come at the expense of overall field performance, including poor yields. Here, we engineer superhigh oleic (SHO) safflower producing a seed oil with 93% oleic generated from seed produced in multisite field trials spanning five generations. SHO safflower oil is the result of seed-specific hairpin-based RNA interference of two safflower lipid biosynthetic genes, FAD2.2 and FATB, producing seed oil containing less than 1.5% polyunsaturates and only 4% saturates but with no impact on lipid profiles of leaves and roots. Transgenic SHO events were compared to non-GM safflower in multisite trial plots with a wide range of growing season conditions, which showed no evidence of impact on seed yield. The oxidative stability of the field-grown SHO oil produced from various sites was 50 h at 110°C compared to 13 h for conventional ~80% oleic safflower oils. SHO safflower produces a uniquely stable vegetable oil across different field conditions that can provide the scale of production that is required for meeting the global demands for high stability oils in food and the oleochemical industry.

Expression of 16 Nitrogenase Proteins within the Plant Mitochondrial Matrix

The industrial production and use of nitrogenous fertilizer involves significant environmental and economic costs. Strategies to reduce fertilizer dependency are required to address the world's increasing demand for sustainable food, fibers, and biofuels. Biological nitrogen fixation, a process unique to diazatrophic bacteria, is catalyzed by the nitrogenase complex, and reconstituting this function in plant cells is an ambitious biotechnological strategy to reduce fertilizer use. Here we establish that the full array of biosynthetic and catalytic nitrogenase (Nif) proteins from the diazotroph Klebsiella pneumoniae can be individually expressed as mitochondrial targeting peptide (MTP)-Nif fusions in Nicotiana benthamiana. We show that these are correctly targeted to the plant mitochondrial matrix, a subcellular location with biochemical and genetic characteristics potentially supportive of nitrogenase function. Although Nif proteins B, D, E, F, H, J, K, M, N, Q, S, U, V, X, Y, and Z were all detectable by Western blot analysis, the NifD catalytic component was the least abundant. To address this problem, a translational fusion between NifD and NifK was designed based on the crystal structure of the nitrogenase MoFe protein heterodimer. This fusion protein enabled equimolar NifD:NifK stoichiometry and improved NifD expression levels in plants. Finally, four MTP-Nif fusion proteins (B, S, H, Y) were successfully co-expressed, demonstrating that multiple components of nitrogenase can be targeted to plant mitochondria. These results establish the feasibility of reconstituting the complete componentry for nitrogenase in plant cells, within an intracellular environment that could support the conversion of nitrogen gas into ammonia.

Internet connectivity among rural Alabama veterans: baseline findings from the Alabama Veterans Rural Health Initiative Project

INTRODUCTION

The purpose of this secondary data analysis was to characterize the Internet usage of rural veterans (n=201) who had either never enrolled, or had previously enrolled but not accessed, Veterans Affairs (VA) health services in at least 2 years. The VA Office of Rural Health (ORH)(ie part of the United States Government Department of Veterans Affairs) is a government agency with the mission to improve access and quality of care for enrolled rural and highly rural US veterans. The ORH seeks to use evidence-based policies and innovative practices to support the unique needs of enrolled veterans residing in geographically remote areas. These individuals represent a population considered to experience health disparities secondary to reduced health care access.

METHODS

This study explored the role of the Internet in providing health information and information regarding VA services to rural Caucasian and African American veterans in the southeastern USA. African Americans were significantly younger (50.32 years, SD=13.50, range 22-85 years) than Caucasian rural veterans (58.50 years, SD=13.82, range 21-85 years).

RESULTS

A small majority of veterans (n=107; 53.23%) reported 'going on-line to use the Internet or World Wide Web, or to send and receive e-mail'. Among Internet users, multivariate logistic regression showed that neither age nor race/ethnicity predicted using the Internet to access health information or information regarding VA services.

CONCLUSION

In comparison with population norms, rural veterans displayed lower usage of the Internet; however, there were few practical age differences between young, middle-aged and older rural veterans in use of the Internet for seeking health information. These results suggest a tremendous potential for online outreach efforts to rural veterans seeking health information and information regarding VA services and benefits. The US Federal Government's VA Office of Rural Health is investing in technology-based services and will need to disseminate information regarding the availability of these services to rural veterans.

Facile mutant identification via a single parental backcross method and application of whole genome sequencing based mapping pipelines

Forward genetic screens have identified numerous genes involved in development and metabolism, and remain a cornerstone of biological research. However, to locate a causal mutation, the practice of crossing to a polymorphic background to generate a mapping population can be problematic if the mutant phenotype is difficult to recognize in the hybrid F2 progeny, or dependent on parental specific traits. Here in a screen for leaf hyponasty mutants, we have performed a single backcross of an Ethane Methyl Sulphonate (EMS) generated hyponastic mutant to its parent. Whole genome deep sequencing of a bulked homozygous F2 population and analysis via the Next Generation EMS mutation mapping pipeline (NGM) unambiguously determined the causal mutation to be a single nucleotide polymorphisim (SNP) residing in HASTY, a previously characterized gene involved in microRNA biogenesis. We have evaluated the feasibility of this backcross approach using three additional SNP mapping pipelines; SHOREmap, the GATK pipeline, and the samtools pipeline. Although there was variance in the identification of EMS SNPs, all returned the same outcome in clearly identifying the causal mutation in HASTY. The simplicity of performing a single parental backcross and genome sequencing a small pool of segregating mutants has great promise for identifying mutations that may be difficult to map using conventional approaches.

A phase Ib study of vosaroxin, an anticancer quinolone derivative, in patients with relapsed or refractory acute leukemia

This study of vosaroxin evaluated dose-limiting toxicity (DLT), maximum-tolerated dose (MTD), pharmacokinetics (PK), clinical activity and pharmacodynamics in relapsed/refractory leukemia. Dosing was weekly (days 1, 8 and 15) or twice weekly (days 1, 4, 8 and 11). Seventy-three treated patients had a median age of 65 years, 85% had acute myeloid leukemia and 78% had refractory disease. Weekly schedule: 42 patients received 18-90 mg/m(2); MTD was 72 mg/m(2). Twice-weekly schedule: 31 patients received 9-50 mg/m(2); MTD was 40 mg/m(2). DLT was stomatitis; primary non-hematologic toxicity was reversible gastrointestinal symptoms and febrile neutropenia. Thirty-day all-cause mortality was 11%. Five patients had complete or incomplete remissions; median duration was 3.1 months. A morphologic leukemia-free state (bone marrow blast reduction to <5%) occurred in 11 additional patients. Antileukemic activity was associated with total dose or weekly time above 1 μmol/l plasma vosaroxin concentration (P<0.05). Vosaroxin exposure was dose proportional over 9-90 mg/m(2). The average terminal half-life was ~25 h and clearance was non-renal. No induction or inhibition of vosaroxin metabolism was evident. Vosaroxin-induced DNA damage was detected as increased intracellular γH2AX. Vosaroxin had an acceptable safety profile, linear PK and encouraging clinical activity in relapsed/refractory leukemia.

The microRNA159-regulated GAMYB-like genes inhibit growth and promote programmed cell death in Arabidopsis

The microRNA159 (miR159) family represses the conserved GAMYB-like genes that encode R2R3 MYB domain transcription factors that have been implicated in gibberellin (GA) signaling in anthers and germinating seeds. In Arabidopsis (Arabidopsis thaliana), the two major miR159 family members, miR159a and miR159b, are functionally specific for two GAMYB-like genes, MYB33 and MYB65. These transcription factors have been shown to be involved in anther development, but there are differing reports about their role in the promotion of flowering and little is known about their function in seed germination. To understand the function of this pathway, we identified the genes and processes controlled by these GAMYB-like genes. First, we demonstrate that miR159 completely represses MYB33 and MYB65 in vegetative tissues. We show that GA does not release this repression and that these transcription factors are not required for flowering or growth. By contrast, in the absence of miR159, the deregulation of MYB33 and MYB65 in vegetative tissues up-regulates genes that are highly expressed in the aleurone and GA induced during seed germination. Confirming that these genes are GAMYB-like regulated, their expression was reduced in myb33.myb65.myb101 seeds. Aleurone vacuolation, a GA-mediated programmed cell death process required for germination, was impaired in these seeds. Finally, the deregulation of MYB33 and MYB65 in vegetative tissues inhibits growth by reducing cell proliferation. Therefore, we conclude that miR159 acts as a molecular switch, only permitting the expression of GAMYB-like genes in anthers and seeds. In seeds, these transcription factors participate in GA-induced pathways required for aleurone development and death.

Metabolic engineering of morphinan alkaloids by over-expression and RNAi suppression of salutaridinol 7-O-acetyltransferase in opium poppy

We demonstrate that both over-expression and suppression of the gene encoding the morphinan pathway enzyme salutaridinol 7-O-acetyltransferase (SalAT) in opium poppy affects the alkaloid products that accumulate. Over-expression of the gene in most of the transgenic events resulted in an increase in capsule morphine, codeine and thebaine on a dry-weight basis. The transgenic line with the highest alkaloid content had 41%, 37% and 42% greater total alkaloids than the control in three independent trials over 3 years. DNA-encoded hairpin RNA-mediated suppression of SalAT resulted in the novel accumulation of the alkaloid salutaridine at up to 23% of total alkaloid; this alkaloid is not detectable in the parental genotype. Salutaridine is not the substrate of SalAT but the substrate of the previous enzyme in the pathway, salutaridine reductase. RNA transcript analysis of 16 primary T0 transformants and their segregating T1 progeny revealed an average reduction in SalAT transcript to about 12% of the control. Reduction in SalAT transcript was evident in both leaves and latex. Reverse transcriptase PCR and high-performance liquid chromatography analyses confirmed cosegregation of the expressed transgene with the salutaridine accumulating phenotype.

Increasing morphinan alkaloid production by over-expressing codeinone reductase in transgenic Papaver somniferum

Only plants of the Papaver genus (poppies) are able to synthesize morphinan alkaloids, and cultivation of P. somniferum, opium poppy, remains critical for the production and supply of morphine, codeine and various semi-synthetic analgesics. Opium poppy was transformed with constitutively expressed cDNA of codeinone reductase (PsCor1.1), the penultimate step in morphine synthesis. Most transgenic lines showed significant increases in capsule alkaloid content in replicated glasshouse and field trials over 4 years. The morphinan alkaloid contents on a dry weight basis were between 15% and 30% greater than those in control high-yielding genotypes and control non-transgenic segregants. Transgenic leaves had approximately 10-fold greater levels of Cor transcript compared with non-transgenic controls. Two cycles of crossing of the best transgenic line into an elite high-morphine genotype resulted in significant increases in morphine and total alkaloids relative to the elite recurrent parent. No significant changes in alkaloid profiles or quantities were observed in leaf, roots, pollen and seed.

Opium Poppy (Papaver somniferum)

The genetic transformation of opium poppy, Papaver somniferum, offers the opportunity to study the mechanisms involved in the regulation of benzylisoquinoline and morphinan alkaloid biosynthesis. The development of an efficient transformation protocol for opium poppy has allowed us to transform a range of genotypes from all around the world, including previously recalcitrant high-yielding commercial Australian cultivars. The method involves Agrobacterium tumefaciens infection of hypocotyl explants, followed by the production of antibiotic or herbicide resistant embryogenic callus, the subsequent induction of somatic embryos and development into normal plants. The use of different selective agents, binary vectors, and poppy genotypes has demonstrated the robustness and reliability of this protocol in the production of many hundreds of confirmed transgenic poppies.

Transformation of opium poppy (Papaver somniferum L.) with antisense berberine bridge enzyme gene (anti-bbe) via somatic embryogenesis results in an altered ratio of alkaloids in latex but not in roots

The berberine bridge enzyme cDNA bbe from Papaver somniferum L. was transformed in antisense orientation into seedling explants of the industrial elite line C048-6-14-64. In this way, 84 phenotypically normal To plants derived from embryogenic callus cultures were produced. The selfed progeny of these 84 plants yielded several T1 plants with an altered alkaloid profile. One of these plants T1-47, and its siblings T2-1.2 and T2-1.5 are the subject of the present work. The transformation of these plants was evaluated by PCR, and northern and Southern hybridisation. The transgenic plants contained one additional copy of the transgene. The alkaloid content in latex and roots was determined with HPLC and LC-MS. We observed an increased concentration of several pathway intermediates from all biosynthetic branches, e.g., reticuline, laudanine, laudanosine, dehydroreticuline, salutaridine and (S)-scoulerine. The transformation altered the ratio of morphinan and tetrahydrobenzylisoquinoline alkaloids in latex but not the benzophenanthridine alkaloids in roots. The altered alkaloid profile is heritable at least to the T2 generation. These results are the first example of metabolic engineering of the alkaloid pathways in opium poppy and, to our knowledge, the first time that an alkaloid biosynthetic gene has been transformed into the native species, followed by regeneration into a mature plant to enable analyses of the effect of the transgene on metabolism over several generations.

RNAi-mediated replacement of morphine with the nonnarcotic alkaloid reticuline in opium poppy

We report on the silencing of codeinone reductase (COR) in the opium poppy, Papaver somniferum, using a chimeric hairpin RNA construct designed to silence all members of the multigene COR family through RNA interference (RNAi). After gene silencing, the precursor alkaloid (S)-reticuline-seven enzymatic steps upstream of codeinone-accumulated in transgenic plants at the expense of morphine, codeine, oripavine and thebaine. Methylated derivatives of reticuline also accumulated. Analysis verified loss of Cor gene transcript, appearance of 22-mer degradation products and reduction of enzyme activity. The surprising accumulation of (S)-reticuline suggests a feedback mechanism preventing intermediates from general benzylisoquinoline synthesis entering the morphine-specific branch. However transcript levels for seven other enzymes in the pathway, both before and after (S)-reticuline, were unaffected. This is the first report of gene silencing in transgenic opium poppy and of metabolic engineering to cause the high-yield accumulation of the nonnarcotic alkaloid reticuline.

Genetic transformation in commercial Tasmanian cultivars of opium poppy, Papaver somniferum, and movement of transgenicpollen in the field

We report a new transformation protocol for the pharmaceutically important opium poppy, Papaver somniferum L.; the protocol allows transformation for the first time of high yielding commercial cultivars. The method involves Agrobacterium tumefaciens infection of hypocotyl explants, followed by the production of antibiotic- or herbicide-resistant embryogenic callus and the subsequent induction of somatic embryos and plants. Key elements of the improvement are the use of buffering agents to stabilise medium pH and bottom-cooling of the cultures. Transformation was verified by PCR and Southern blot hybridisation. Transcription of transgenes was confirmed by RT-PCR and product sequencing. Expression of transgenes was detected by histochemical GUS staining, phosphinothricin acetyltransferase (PAT) enzyme assays for bar and pat genes, and western analysis of transgenic sunflower seed albumin protein. Expression of various transgenes was detected in stem, leaf, seed, capsule and latex. The pat gene was demonstrated to be stably inherited to the T₂ generation and to confer phosphinothricin (PPT) herbicide resistance. Most T₀ plants showed normal morphology, were self-fertile and the transgenes displayed the expected Mendelian segregation. The percentage of explants producing somatic embryos that developed into plantlets able to be transplanted to soil, ranged from 6-11% in two Tasmanian cultivars.A field trial using pat transgenic plants was designed to estimate the frequency of hybridisation at various distances into buffer rows of non-transgenic poppies and to related weed species, P. somniferum spp. setigerum and P. dubium. The frequency of hybridisation to completely compatible poppy fell sharply with distance, being 2.6% at 20 cm, 2.13% at 0.5 m and falling to 0% at 2.5 and 5 m. No hybridisation could be detected to two weed species under open pollination conditions, including the compatible P. somniferum spp. setigerum, when grown as close as 20 cm, despite flowering at the same time as the transgenic plants in the presence of foraging bees.

Geriatric sleep apnea syndrome: a preliminary description

We compared 8 patients diagnosed with geriatric sleep apnea syndrome (GSAS) with 12 healthy older controls (GCON) matched on age, sex, weight, education, and socioeconomic standing. GSAS was diagnosed if patients had an apnea + hypopnea index (AHI) greater than or equal to 10 and an impairment involving at least two of the following: hypertension, cardiac arrhythmias, or daytime hypersomnolence. In addition to significant differences on selection variables (e.g., AHI, frequency of hypertension, Multiple Sleep Latency Test), GSAS patients had significantly more sleep disturbance, were sleepier on subjective measures, were more depressed, and had lower scores on tests of nonverbal problem solving and nonverbal memory. Thus, GSAS resembles SAS described in middle-aged populations. More research is needed to determine the most efficient diagnostic parameters for identifying pathological levels of SDB in older persons.

Sleep-disordered breathing in healthy aged persons: one-year follow-up of daytime sequelae

We studied the waking medical, sleep, and psychological status of 28 healthy older persons who had undergone nocturnal polysomnography and daytime assessment approximately 1-year earlier. In a previous report based on this sample, we found that sleep-disordered breathing (SDB) indices were not related to concurrent measurements of daytime functioning. However, in the present study, we observed relationships between the original SDB indices and several measures of cardiopulmonary functioning obtained 1 year later. At follow-up, subjects with originally high levels of SDB had significantly higher systolic blood pressure and poorer pulmonary function test results, were more likely to report irregular heartbeats in the previous year, and had experienced more disruptive snoring than the remaining subjects. When combined with other recent data, these results raise the possibility that SDB exerts an insidious pathological influence on the health and daytime functioning of otherwise healthy older persons.

Elevation of plasma neuropeptide Y levels in congestive heart failure

PURPOSE

Our objectives were to assess whether plasma neuropeptide Y (NPY) levels are elevated in patients with congestive heart failure (CHF) and whether or not NPY levels can serve as a reliable indicator of sympathetic activity in CHF.

PATIENTS AND METHODS

Plasma levels of the sympathetic neurotransmitters norepinephrine and epinephrine and of the sympathetic co-transmitter NPY were measured in 17 patients with CHF and 14 healthy control subjects at rest and after maximal exercise.

RESULTS

Under resting conditions, plasma NPY and norepinephrine levels were elevated in patients with CHF compared with control subjects (551 +/- 48 pg/ml versus 311 +/- 22 pg/ml, p less than or equal to 0.001 for NPY, and 306 +/- 73 pg/ml versus 124 +/- 22 pg/ml, p less than or equal to 0.02 for norepinephrine). Plasma NPY correlated better with plasma norepinephrine than with epinephrine, indicating its origin from sympathetic nerve terminals. Acute stimulation of sympathetic activity by dynamic exercise increased plasma norepinephrine levels in control subjects and patients with CHF, but did not significantly alter the mean plasma NPY value in the latter group.

CONCLUSION

NPY may play a role in the pathophysiology of CHF.

Pseudopseudotumor cerebri: meningeal carcinomatosis presenting as benign intracranial hypertension

We have described a 63-year-old man, taking diethylstilbestrol for adenocarcinoma of the prostate, who had papilledema. Lumbar puncture revealed intracranial hypertension without pleiocytosis. CT scan was normal, consistent with the diagnosis of pseudotumor cerebri. At craniotomy for placement of a ventriculoperitoneal shunt, the dura was found to be infiltrated with adenocarcinoma. In patients with known malignancy and elevated intracranial pressure, lumbar puncture and CT scan alone are not enough to rule out meningeal carcinomatosis; repeated lumbar puncture or cervical cisternal puncture may be necessary to document malignant cytology.

Failure of T cells specific for strong histocompatibility antigens to cooperate with B cells for a humoral response

Thymus-derived lymphocytes (T cells) selected for reactivity to strong histocompatibility antigens over a period of one to twelve months in vitro were tested for their ability to cooperate with bone marrow-derived lymphocytes (B cells) for a humoral response. If cultured with normal syngeneic or allogeneic spleen cells and sheep erythrocytes (SRBC) as immunogen, inhibition of the anti-SRBC response was observed. Similarly, in T cell-free spleen cells the alloreactive T cells did not stimulate a humoral response, indicating that they cannot exert cooperative activity on B cells. Since it was possible that the alloreactive T cells may cooperate with B cells in a humoral response to immunogens carrying histocompatibility antigens, hapten-coupled tumor cells were also used as immunogen. Though it is demonstrated that the alloreactive T cells do recognize the tumor cell immunogen, no stimulation of the B cells for a humoral response against the tumor cell is observed. This result, as well as the finding that the antigenic requirements for T helper cell priming and cell proliferation of the alloreactive T cells are different, suggests that these alloreactive T cells and helper T cells belong to different T cell subsets.