Plant Poly(ADP-Ribose) Polymerase 1 Is a Potential Mediator of Cross-Talk between the Cajal Body Protein Coilin and Salicylic Acid-Mediated Antiviral Defence

The nucleolus and Cajal bodies (CBs) are sub-nuclear domains with well-known roles in RNA metabolism and RNA-protein assembly. However, they also participate in other important aspects of cell functioning. This study uncovers a previously unrecognised mechanism by which these bodies and their components regulate host defences against pathogen attack. We show that the CB protein coilin interacts with poly(ADP-ribose) polymerase 1 (PARP1), redistributes it to the nucleolus and modifies its function, and that these events are accompanied by substantial increases in endogenous concentrations of salicylic acid (SA), activation of SA-responsive gene expression and callose deposition leading to the restriction of tobacco rattle virus (TRV) systemic infection. Consistent with this, we also find that treatment with SA subverts the negative effect of the pharmacological PARP inhibitor 3-aminobenzamide (3AB) on plant recovery from TRV infection. Our results suggest that PARP1 could act as a key molecular actuator in the regulatory network which integrates coilin activities as a stress sensor for virus infection and SA-mediated antivirus defence.

Two decades of changing anthropogenic mercury emissions in Australia: inventory development, trends, and atmospheric implications

Mercury is a toxic environmental pollutant emitted into the atmosphere by both natural and anthropogenic sources. In Australia, previous estimates of anthropogenic mercury emissions differ by up to a factor of three, with existing inventories either outdated or inaccurate and several lacking Australia-specific input data. Here, we develop a twenty-year inventory of Australian anthropogenic mercury emissions spanning 2000-2019 with annual resolution. Our inventory uses Australia-specific data where possible and incorporates processes not included in other Australian inventories, such as delayed release effects from waste emissions. We show that Australian anthropogenic mercury emissions have decreased by more than a factor of two over the past twenty years, with the largest decrease from the gold production sector followed by brown coal-fired power plants and commercial product waste. Only the aluminium sector has shown a notable increase in mercury emissions. Using a global 3-D chemical transport model (GEOS-Chem), we show that the reduction in emissions has led to a small decrease in mercury deposition to the Australian continent, with annual oxidised mercury deposition ∼3-4% lower with present day emissions than with emissions from the year 2000. We also find that Australian emissions are not accurately represented in recent global emissions inventories and that differences between inventories have a larger impact than emissions trends on simulated mercury deposition. Overall, this work suggests a significant benefit to Australia from the Minamata Convention, with further reductions to Australian mercury deposition expected from decreases in both Australian and global anthropogenic emissions.

Glia actively sculpt sensory neurons by controlled phagocytosis to tune animal behavior

Glia in the central nervous system engulf neuron fragments to remodel synapses and recycle photoreceptor outer segments. Whether glia passively clear shed neuronal debris or actively prune neuron fragments is unknown. How pruning of single-neuron endings impacts animal behavior is also unclear. Here, we report our discovery of glia-directed neuron pruning in Caenorhabditis elegans. Adult C. elegans AMsh glia engulf sensory endings of the AFD thermosensory neuron by repurposing components of the conserved apoptotic corpse phagocytosis machinery. The phosphatidylserine (PS) flippase TAT-1/ATP8A functions with glial PS-receptor PSR-1/PSR and PAT-2/α-integrin to initiate engulfment. This activates glial CED-10/Rac1 GTPase through the ternary GEF complex of CED-2/CrkII, CED-5/DOCK180, CED-12/ELMO. Execution of phagocytosis uses the actin-remodeler WSP-1/nWASp. This process dynamically tracks AFD activity and is regulated by temperature, the AFD sensory input. Importantly, glial CED-10 levels regulate engulfment rates downstream of neuron activity, and engulfment-defective mutants exhibit altered AFD-ending shape and thermosensory behavior. Our findings reveal a molecular pathway underlying glia-dependent engulfment in a peripheral sense-organ and demonstrate that glia actively engulf neuron fragments, with profound consequences on neuron shape and animal sensory behavior.

Neurons are tree-shaped cells that receive information through endings connected to neighbouring cells or the environment. Controlling the size, number and location of these endings is necessary to ensure that circuits of neurons get precisely the right amount of input from their surroundings.

Glial cells form a large portion of the nervous system, and they are tasked with supporting, cleaning and protecting neurons. In humans, part of their duties is to ‘eat’ (or prune) unnecessary neuron endings. In fact, this role is so important that defects in glial pruning are associated with conditions such as Alzheimer’s disease. Yet it is still unknown how pruning takes place, and in particular whether it is the neuron or the glial cell that initiates the process.

To investigate this question, Raiders et al. enlisted the common laboratory animal Caenorhabditis elegans, a tiny worm with a simple nervous system where each neuron has been meticulously mapped out. First, the experiments showed that glial cells in C. elegans actually prune the endings of sensory neurons. Focusing on a single glia-neuron pair then revealed that the glial cell could trim the endings of a living neuron by redeploying the same molecular machinery it uses to clear dead cell debris. Compared to this debris-clearing activity, however, the glial cell takes a more nuanced approach to pruning: specifically, it can adjust the amount of trimming based on the activity load of the neuron.

When Raiders et al. disrupted the glial pruning for a single temperature-sensing neuron, the worm lost its normal temperature preferences; this demonstrated how the pruning activity of a single glial cell can be linked to behavior.

Taken together the experiments showcase how C. elegans can be used to study glial pruning. Further work using this model could help to understand how disease emerges when glial cells cannot perform their role, and to spot the genetic factors that put certain individuals at increased risk for neurological and sensory disorders.

Application of the Theoretical Domains Framework to identify factors that influence hand hygiene compliance in long-term care

BACKGROUND

Healthcare worker (HCW) hand hygiene compliance is key to patient safety; however, compliance is suboptimal. Nevertheless hand hygiene compliance is not well studied in the long-term care setting.

AIM

To apply a behaviour change framework, the Theoretical Domains Framework (TDF), to identify modifiable facilitators and barriers for HCW hand hygiene compliance in long-term care settings.

METHODS

HCW hand hygiene compliance facilitators and barriers were examined using a questionnaire for HCWs from long-term care homes in Ontario, Canada. The questionnaire was informed by the TDF, which is based on a synthesis of constructs from a number of relevant psychological theories of behaviour change.

FINDINGS

Barriers identified from the questionnaire aligned with the TDF domain environmental context and resources (time pressure, workload, and environmental controls). Facilitators identified from questionnaire results aligned with the TDF domains social/professional role and identity (it is what is expected of HCWs), and beliefs about consequences (risk of transmission of micro-organisms to self or others).

CONCLUSION

There are several barriers to hand hygiene compliance that persist in long-term care. A behaviour change theory-informed framework such as the TDF can be helpful to identify those barriers. This study identified several key behavioural constructs aligned with the TDF that can be targeted when developing novel hand hygiene interventions.

Body weight, body image and primary postpartum haemorrhage: a review of the literature

The prevalence of obesity during pregnancy is rising. Elevated BMI is a significant risk factor for adverse maternal and fetal outcomes, including primary postpartum haemorrhage (PPH). Addressing the issues surrounding obesity in pregnancy presents many biological, social and psychological challenges. BMI is an easily measured and modifiable anthropometrical risk factor and should be recorded in all pregnancies. BMI should be proactively managed prior to and during pregnancy. All women should be educated as to the risks of an elevated BMI during pregnancy and those at risk should have access to specialist medical and surgical support if required. Our aim was to investigate the associations between elevated BMI and adverse maternal and fetal outcomes including PPH, and to explore the psychological challenges of having an elevated BMI during pregnancy.

Status and prospects of plant virus control through interference with vector transmission

Most plant viruses rely on vector organisms for their plant-to-plant spread. Although there are many different natural vectors, few plant virus-vector systems have been well studied. This review describes our current understanding of virus transmission by aphids, thrips, whiteflies, leafhoppers, planthoppers, treehoppers, mites, nematodes, and zoosporic endoparasites. Strategies for control of vectors by host resistance, chemicals, and integrated pest management are reviewed. Many gaps in the knowledge of the transmission mechanisms and a lack of available host resistance to vectors are evident. Advances in genome sequencing and molecular technologies will help to address these problems and will allow innovative control methods through interference with vector transmission. Improved knowledge of factors affecting pest and disease spread in different ecosystems for predictive modeling is also needed. Innovative control measures are urgently required because of the increased risks from vector-borne infections that arise from environmental change.

Risk factors for yeast superinfection in the treatment of suspected exit site infections: a case-control study

PURPOSE

The risk of infection can be reduced in hemodialysis (HD) patients with central venous catheters (CVCs) by using prophylactic intranasal mupirocin or polysporin at the exit site. However, there are concerns about the potential emergence of resistant microorganisms. The purpose of our study was to determine if the use of polysporin double in the treatment of exit site infections was associated with the emergence of yeast positive exit site cultures.

METHODS

In this case control study, we evaluated the risk of developing yeast positive exit site cultures after introducing a polysporin medical directive for the treatment of presumed exit site infections in our HD units. All HD patients using a CVC for blood access at the Ottawa Hospital were eligible for study. Demographic variables, use of polysporin, antibiotics and immunosuppressive medications were compared between those patients with yeast positive exit site cultures and controls.

RESULTS

There was no differences in age, gender or diabetic status between the cases and controls. However, the use of polysporin, antibiotics and immunocompromised status were associated with an increased risk of yeast positive exit site cultures. The relative importance of each of these factors could not be determined using this study design and requires future prospective study.

CONCLUSIONS

The emergence of yeast positive exit site cultures after the introduction of a new medical directive at a tertiary care hospital highlights the difference between medications used for prophylaxis and those used for treatment of CVC infections in high risk dialysis patients.

A comparison of the efficacy and safety of olanzapine and risperidone in the treatment of elderly patients with schizophrenia: an open study of six months duration

BACKGROUND

Following an earlier study in which elderly patients with schizophrenia had their typical antipsychotic medication changed to olanzapine or risperidone, the 61 patients were followed for up to a further six months to see if either treatment was superior in terms of efficacy or side effects.

AIMS

To determine whether either olanzapine or risperidone was superior in terms of efficacy or side effects when treating schizophrenia in late life.

METHODS

Psychiatric symptoms, side effects and quality of life were rated every six weeks for 24 weeks of open label comparative treatment using standard measures. Group differences were examined using analysis of covariance and within-group changes over time were assessed using paired t-tests.

RESULTS

There were 34 olanzapine and 32 risperidone patients who entered the study, but intention to treat data was only available for 61 of the 66 patients. There were no clinical or demographic differences between the groups. Parkinsonism, positive and negative symptoms of schizophrenia improved in both groups both from baseline switch to olanzapine or risperidone and during the six month follow-up after completion of crossover. No significant differences were seen between groups on most measures. However, patients treated with olanzapine showed a significantly greater improvement in quality of life from baseline compared to risperidone patients.

CONCLUSIONS

Both drugs were well tolerated and their use was associated with fewer symptoms of schizophrenia and less adverse effects than were seen when the patients were taking a typical antipsychotic at baseline. Olanzapine appears to have particular benefit with regard to quality of life.

Immunological detection and mutational analysis of the RNA2-encoded nematode transmission proteins of pea early browning virus

Pea early browning virus (PEBV) is transmitted between plants by root-feeding trichodorid nematodes. Mutagenesis studies have implicated two non-structural viral proteins in the transmission process. These two proteins [the 29 kDa ('29K') protein and the 23K protein] were expressed in bacteria and used to raise antibodies. In Western blotting experiments, the antibodies detected both of these virus proteins in leaves and roots of infected Nicotiana bethamiana and N. clevelandii plants. Periodate treatment of proteins transferred to nitrocellulose membranes suggested that the PEBV 23K protein may be glycosylated. A PEBV mutant was constructed lacking the complete 23K coding sequence. The mutant was able systemically to infect Nicotiana spp. but caused striking chlorotic ringspot leaf symptoms and stunting of both leaves and roots. These symptoms were absent in plants doubly-infected with the mutant and wild-type PEBV. The 23K gene deletion mutant was transmitted by nematodes at a much reduced frequency compared to wild-type virus, indicating that the 23K protein is involved in but not essential for vector transmission. Western immuno-blot and ELISA experiments revealed that the reduction in the nematode-transmissibility of PEBV carrying mutations in the 23K gene did not result from interference in the expression of the 29K transmission protein or from gross changes in the titre of virus in the roots of infected plants.

Replication of maize streak virus mutants in maize protoplasts: evidence for a movement protein

We have used protoplasts derived from a maize (Black Mexican Sweet) suspension culture to study the replication of maize streak virus (MSV) wild-type (wt) and mutant DNA genomes. Following inoculation with plasmids containing multimeric copies of MSV, both single-stranded (ss) and double-stranded MSV DNA forms were produced, in proportions relative to those seen in infected plants. The immunodetection of coat protein (PV2) and geminate particles confirmed that the protoplasts were able to support the entire multiplication cycle of MSV and therefore were suitable for the study of MSV gene function. Inoculation of protoplasts with V1 gene mutants which are unable to produce systemic infections in plants resulted in DNA replication and encapsidation indistinguishable from that obtained with wt constructs implicating the protein in virus movement. Computer analysis of the V1 protein (PV1) indicated a potential trans-membrane or membrane-embedded domain. Following inoculation of protoplasts with V2 mutants, ssDNA was not detected; the inability of these mutants to spread in plants may be due to a lack of ssDNA, PV2, or a combination of the two. The requirements for systemic infection of MSV are discussed.

Supraceliac aortomesenteric bypass for intestinal ischemia

The supraceliac aorta has received little attention as an inflow site of bypass graft origin for mesenteric arterial reconstruction; this article describes our experience with its use in 10 patients. Ten patients underwent bypass grafts (three vein and seven prosthetic grafts) from the supraceliac aorta incorporating the celiac axis to the superior mesenteric artery. All patients had two- or three-vessel mesenteric arterial occlusion. No operative deaths occurred. Nine patients were studied with postoperative arteriography. Nine of ten patients have had satisfactory results on follow-up from 5 to 99 months (mean 43 months), although two patients required operative revision to achieve this. The operative technique is described, including approach to the aorta in the lower mediastinum via upper abdominal exposure and pancreatic displacement to expose the superior mesenteric artery. This method permits avoidance of the infrarenal aorta, if desired because of atherosclerotic disease or previous operation. Antegrade supraceliac aortomesenteric grafts avoid turbulence and compression of conventional "retrograde" bypass beneath the mesentery. We conclude that supraceliac aortic grafts provide a useful visceral artery reconstruction technique.

A comparison between the handling of iodine and technetium by the thyroid gland of the rat

The relative affinities of the thyroid gland for 131I and 99mTcO4 and the further metabolism of these isotopes were studied in rats. 99mTcO4 is trapped to an extent almost identical to 131I in the thyroid. This process is inhibited by KClO4 and stimulated by thyroid-stimulating hormone. 99mTcO4 having been trapped is further metabolized in the thyroid gland.

Concentration of bromine-82 in the thyroid gland of rats

The concentration of 82Br in the thyroid gland, muscle and blood was studied in rats. In untreated animals the radioactivity per unit weight of thyroid was greater than that of muscle but less than that of blood. This radioactivity in the thyroid remained constant with time and was unaffected by perchlorate. After stimulation by endogenous thyroid-stimulating hormone (TSH) the thyroidal concentration increased to a level slightly greater than that in blood. This effect was inhibited by perchlorate. It is concluded that, while under normal conditions bromine is not concentrated by the thyroid, after stimulation by TSH there is an increased uptake by the gland. There is no evidence that bromine is metabolized further in the thyroid gland.

Iodine excretion in urine, saliva, gastric juice and sweat in dehalogenase deficiency

The excretion of iodine in urine, saliva, gastric juice and sweat has been studied by using 131I-labelled monoiodotyrosine in a patient with the dehalogenase type of dyshormonogenesis. Iodinated components 'x', iodide, monoiodotyrosine and 'y' were found in the urine. A previously undescribed component (compound 'u') accounted for a large fraction of the urinary radioactive iodine. Organic iodinated compounds were not excreted in the saliva. Only inorganic iodide was found in the gastric juice. No organic iodine was detected in the sweat. The plasma inorganic iodine (PII) derived from salivary iodine measurements gave low values indicative of iodine deficiency. The PII values obtained from the urinary iodine were falsely high due to the presence of organic iodinated compounds.