Tobamoviruses: Special Issue Editorial

Tobamoviruses are plant-infecting viruses with an ancient lineage, understood to have arisen during the age of the dinosaurs in the Cretaceous period 145-66 million years ago [...].

Virome Analysis of Aconitum carmichaelii Reveals Infection by Eleven Viruses, including Two Potentially New Species

Aconitum carmichaelii is a herbaceous herb indigenous to China that has been cultivated for traditional medicine for centuries. Virus-like symptoms of A. carmichaelii plants were observed on leaves in some A. carmichaelii plantations in Zhanyi and Wuding Counties, Yunnan Province, southwest China. High-throughput sequencing (HTS) was performed on 28 symptomatic plants, and the results revealed infection with 11 viruses, including 2 novel viruses and 9 previously described viruses: Aconitum amalgavirus 1 (AcoAV-1), aconite virus A (AcVA), cucumber mosaic virus (CMV), currant latent virus (CuLV), apple stem grooving virus (ASGV), chilli veinal mottle virus (ChiVMV), tomato spotted wilt orthotospovirus (TSWV), tobacco vein distorting virus (TVDV), and potato leafroll virus (PLRV). Two novel viruses tentatively named Aconitum potyvirus 1 and Aconitum betapartitivirus 1, were supported by sequence and phylogenetic analysis results of their genomes. We proposed the names Potyvirus aconiti and Betapartitivirus aconiti. RT-PCR assays of 142 plants revealed the predominance and widespread distribution of CMV, AcVA, and AcoPV-1 in plantations. The detection of isolates of CuLV, ASGV, ChiVMV, TSWV, TVDV, and PLRV infections for the first time in A. carmichaelii expands their known host ranges.

State-of-the-Art Plant Virus Research in Australasia

The Special Issue 'State-of-the-Art Plant Virus Research in Australasia' in Viruses provided a fascinating snapshot of plant and fungus virus research being undertaken in Australasia during the final year of the official COVID-19 pandemic [...].

Historical and Scientific Evidence for the Origin and Cultural Importance to Australia's First-Nations Peoples of the Laboratory Accession of Nicotiana benthamiana, a Model for Plant Virology

Nicotiana benthamiana is an indigenous plant species distributed across northern Australia. The laboratory accession (LAB) of N. benthamiana has become widely adopted as a model host for plant viruses, and it is distinct from other accessions morphologically, physiologically, and by having an attenuation-of-function mutation in the RNA-dependent RNA polymerase 1 (NbRdr1) gene, referred to as NbRdr1m. Recent historical evidence suggested LAB was derived from a 1936 collection by John Cleland at The Granites of the Northern Territory, although no scientific evidence was provided. We provide scientific evidence and further historical evidence supporting the origin of LAB as The Granites. Analysis of a herbarium specimen of N. benthamiana collected by Cleland in 1936 revealed that The Granites population contains plants heterozygous for the NbRdr1 locus, having both the functional NbRdr1 and the mutant NbRdr1m alleles. N. benthamiana was an important cultural asset actively utilised as the narcotic Pituri (chewing tobacco) by the Warlpiri Aboriginal people at the site, who prevented women of child-bearing age from consuming it. We propose that Aboriginal people selected some of the unique traits of LAB that have subsequently facilitated its adoption as a model plant, such as lack of seed dormancy, fast maturity, low nornicotine content, and gracility.

Diamine Oxidase-Conjugated Multiwalled Carbon Nanotubes to Facilitate Electrode Surface Homogeneity

Carbon nanomaterials have gained significant interest over recent years in the field of electrochemistry, and they may be limited in their use due to issues with their difficulty in dispersion. Enzymes are prime components for detecting biological molecules and enabling electrochemical interactions, but they may also enhance multiwalled carbon nanotube (MWCNT) dispersion. This study evaluated a MWCNT and diamine oxidase enzyme (DAO)-functionalised screen-printed electrode (SPE) to demonstrate improved methods of MWCNT functionalisation and dispersion. MWCNT morphology and dispersion was determined using UV-Vis spectroscopy (UV-Vis) and scanning electron microscopy (SEM). Carboxyl groups were introduced onto the MWCNT surfaces using acid etching. MWCNT functionalisation was carried out using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and N-Hydroxysuccinimide (NHS), followed by DAO conjugation and glutaraldehyde (GA) crosslinking. Modified C-MWNCT/EDC-NHS/DAO/GA was drop cast onto SPEs. Modified and unmodified electrodes after MWCNT functionalisation were characterised using optical profilometry (roughness), water contact angle measurements (wettability), Raman spectroscopy and energy dispersive X-ray spectroscopy (EDX) (vibrational modes and elemental composition, respectively). The results demonstrated that the addition of the DAO improved MWCNT homogenous dispersion and the solution demonstrated enhanced stability which remained over two days. Drop casting of C-MWCNT/EDC-NHS/DAO/GA onto carbon screen-printed electrodes increased the surface roughness and wettability. UV-Vis, SEM, Raman and EDX analysis determined the presence of carboxylated MWCNT variants from their non-carboxylated counterparts. Electrochemical analysis demonstrated an efficient electron transfer rate process and a diffusion-controlled redox process. The modification of such electrodes may be utilised for the development of biosensors which could be utilised to support a range of healthcare related fields.

Differences in obstetrical care and outcomes associated with the proportion of the obstetrician's shift completed

BACKGROUND

Understanding and improving obstetrical quality and safety is an important goal of professional societies, and many interventions such as checklists, safety bundles, educational interventions, or other culture changes have been implemented to improve the quality of care provided to obstetrical patients. Although many factors contribute to delivery decisions, a reduced workload has addressed how provider issues such as fatigue or behaviors surrounding impending shift changes may influence the delivery mode and outcomes.

OBJECTIVE

The objective was to assess whether intrapartum obstetrical interventions and adverse outcomes differ based on the temporal proximity of the delivery to the attending's shift change.

STUDY DESIGN

This was a secondary analysis from a multicenter obstetrical cohort in which all patients with cephalic, singleton gestations who attempted vaginal birth were eligible for inclusion. The primary exposure used to quantify the relationship between the proximity of the provider to their shift change and a delivery intervention was the ratio of time from the most recent attending shift change to vaginal delivery or decision for cesarean delivery to the total length of the shift. Ratios were used to represent the proportion of time completed in the shift by normalizing for varying shift lengths. A sensitivity analysis restricted to patients who were delivered by physicians working 12-hour shifts was performed. Outcomes chosen included cesarean delivery, episiotomy, third- or fourth-degree perineal laceration, 5-minute Apgar score of <4, and neonatal intensive care unit admission. Chi-squared tests were used to evaluate outcomes based on the proportion of the attending's shift completed. Adjusted and unadjusted logistic models fitting a cubic spline (when indicated) were used to determine whether the frequency of outcomes throughout the shift occurred in a statistically significant, nonlinear pattern RESULTS: Of the 82,851 patients eligible for inclusion, 47,262 (57%) had ratio data available and constituted the analyzable sample. Deliveries were evenly distributed throughout shifts, with 50.6% taking place in the first half of shifts. There were no statistically significant differences in the frequency of cesarean delivery, episiotomy, third- or fourth-degree perineal lacerations, or 5-minute Apgar scores of <4 based on the proportion of the shift completed. The findings were unchanged when evaluated with a cubic spline in unadjusted and adjusted logistic models. Sensitivity analyses performed on the 22.2% of patients who were delivered by a physician completing a 12-hour shift showed similar findings. There was a small increase in the frequency of neonatal intensive care unit admissions with a greater proportion of the shift completed (adjusted P=.009), but the findings did not persist in the sensitivity analysis.

CONCLUSION

Clinically significant differences in obstetrical interventions and outcomes do not seem to exist based on the temporal proximity to the attending physician's shift change. Future work should attempt to directly study unit culture and provider fatigue to further investigate opportunities to improve obstetrical quality of care, and additional studies are needed to corroborate these findings in community settings.

New insights into the evolution of wheat avenin-like proteins in wild emmer wheat (Triticum dicoccoides)

Fifteen full-length wheat grain avenin-like protein coding genes (TaALP) were identified on chromosome arms 7AS, 4AL, and 7DS of bread wheat with each containing five genes. Besides the a- and b-type ALPs, a c type was identified in the current paper. Both a and b types have two subunits, named x and y types. The five genes on each of the three chromosome arms consisted of two x-type genes, two y-type genes, and one c-type gene. The a-type genes were typically of 520 bp in length, whereas the b types were of 850 bp in length, and the c type was of 470 bp in length. The ALP gene transcript levels were significantly up-regulated in Blumeria graminis f. sp. tritici (Bgt)-infected wheat grain caryopsis at early grain filling. Wild emmer wheat [(WEW), Triticum dicoccoides] populations were focused on in our paper to identify allelic variations of ALP genes and to study the influence of natural selection on certain alleles. Consequently, 25 alleles were identified for TdALP-bx-7AS, 13 alleles were identified for TdALP-ax-7AS, 7 alleles were identified for TdALP-ay-7AS, and 4 alleles were identified for TdALP-ax-4AL Correlation studies on TdALP gene diversity and ecological stresses suggested that environmental factors contribute to the ALP polymorphism formation in WEW. Many allelic variants of ALPs in the endosperm of WEW are not present in bread wheat and therefore could be utilized in breeding bread wheat varieties for better quality and elite plant defense characteristics.

Neonatal outcomes of elective early-term births after demonstrated fetal lung maturity

BACKGROUND

Studies of early-term birth after demonstrated fetal lung maturity show that respiratory and other outcomes are worse with early-term birth (37⁰-38⁶ weeks) even after demonstrated fetal lung maturity when compared with full-term birth (39⁰-40⁶ weeks). However, these studies included medically indicated births and are therefore potentially limited by confounding by the indication for delivery. Thus, the increase in adverse outcomes might be due to the indication for early-term birth rather than the early-term birth itself.

OBJECTIVE

We examined the prevalence and risks of adverse neonatal outcomes associated with early-term birth after confirmed fetal lung maturity as compared with full-term birth in the absence of indications for early delivery.

STUDY DESIGN

This is a secondary analysis of an observational study of births to 115,502 women in 25 hospitals in the United States from 2008 through 2011. Singleton nonanomalous births at 37-40 weeks with no identifiable indication for delivery were included; early-term births after positive fetal lung maturity testing were compared with full-term births. The primary outcome was a composite of death, ventilator for ≥2 days, continuous positive airway pressure, proven sepsis, pneumonia or meningitis, treated hypoglycemia, hyperbilirubinemia (phototherapy), and 5-minute Apgar <7. Logistic regression and propensity score matching (both 1:1 and 1:2) were used.

RESULTS

In all, 48,137 births met inclusion criteria; the prevalence of fetal lung maturity testing in the absence of medical or obstetric indications for early delivery was 0.52% (n = 249). There were 180 (0.37%) early-term births after confirmed pulmonary maturity and 47,957 full-term births. Women in the former group were more likely to be non-Hispanic white, smoke, have received antenatal steroids, have induction, and have a cesarean. Risks of the composite (16.1% vs 5.4%; adjusted odds ratio, 3.2; 95% confidence interval, 2.1-4.8 from logistic regression) were more frequent with elective early-term birth. Propensity scores matching confirmed the increased primary composite in elective early-term births: adjusted odds ratios, 4.3 (95% confidence interval, 1.8-10.5) for 1:1 and 3.5 (95% confidence interval, 1.8-6.5) for 1:2 matching. Among components of the primary outcome, CPAP use and hyperbilirubinemia requiring phototherapy were significantly increased. Transient tachypnea of the newborn, neonatal intensive care unit admission, and prolonged neonatal intensive care unit stay (>2 days) were also increased with early-term birth.

CONCLUSION

Even with confirmed pulmonary maturity, early-term birth in the absence of medical or obstetric indications is associated with worse neonatal respiratory and hepatic outcomes compared with full-term birth, suggesting relative immaturity of these organ systems in early-term births.

Preterm neonatal morbidity and mortality by gestational age: a contemporary cohort

BACKGROUND

Although preterm birth <37 weeks' gestation is the leading cause of neonatal morbidity and mortality in the United States, the majority of data regarding preterm neonatal outcomes come from older studies, and many reports have been limited to only very preterm neonates. Delineation of neonatal outcomes by delivery gestational age is needed to further clarify the continuum of mortality and morbidity frequencies among preterm neonates.

OBJECTIVE

We sought to describe the contemporary frequencies of neonatal death, neonatal morbidities, and neonatal length of stay across the spectrum of preterm gestational ages.

STUDY DESIGN

This was a secondary analysis of an obstetric cohort of 115,502 women and their neonates who were born in 25 hospitals nationwide, 2008 through 2011. All liveborn nonanomalous singleton preterm (23.0-36.9 weeks of gestation) neonates were included in this analysis. The frequency of neonatal death, major neonatal morbidity (intraventricular hemorrhage grade III/IV, seizures, hypoxic-ischemic encephalopathy, necrotizing enterocolitis stage II/III, bronchopulmonary dysplasia, persistent pulmonary hypertension), and minor neonatal morbidity (hypotension requiring treatment, intraventricular hemorrhage grade I/II, necrotizing enterocolitis stage I, respiratory distress syndrome, hyperbilirubinemia requiring treatment) were calculated by delivery gestational age; each neonate was classified once by the worst outcome for which criteria was met.

RESULTS

In all, 8334 deliveries met inclusion criteria. There were 119 (1.4%) neonatal deaths. In all, 657 (7.9%) neonates had major morbidity, 3136 (37.6%) had minor morbidity, and 4422 (53.1%) survived without any of the studied morbidities. Deaths declined rapidly with each advancing week of gestation. This decline in death was accompanied by an increase in major neonatal morbidity, which peaked at 54.8% at 25 weeks of gestation. As frequencies of death and major neonatal morbidity fell, minor neonatal morbidity increased, peaking at 81.7% at 31 weeks of gestation. The frequency of all morbidities fell >32 weeks. After 25 weeks, neonatal length of hospital stay decreased significantly with each additional completed week of pregnancy; among babies delivered from 26-32 weeks of gestation, each additional week in utero reduced the subsequent length of neonatal hospitalization by a minimum of 8 days. The median postmenstrual age at discharge nadired around 36 weeks' postmenstrual age for babies born at 31-35 weeks of gestation.

CONCLUSION

Our data show that there is a continuum of outcomes, with each additional week of gestation conferring survival benefit while reducing the length of initial hospitalization. These contemporary data can be useful for patient counseling regarding preterm outcomes.

Complex evolutionary patterns revealed by mitochondrial genomes of the domestic horse

The domestic horse is the most widely used and important stock and recreational animal, valued for its strength and endurance. The energy required by the domestic horse is mainly supplied by mitochondria via oxidative phosphorylation. Thus, selection may have played an essential role in the evolution of the horse mitochondria. Besides, demographic events also affect the DNA polymorphic pattern on mitochondria. To understand the evolutionary patterns of the mitochondria of the domestic horse, we used a deep sequencing approach to obtain the complete sequences of 15 mitochondrial genomes, and four mitochondrial gene sequences, ND6, ATP8, ATP6 and CYTB, collected from 509, 363, 363 and 409 domestic horses, respectively. Evidence of strong substitution rate heterogeneity was found at nonsynonymous sites across the genomes. Signatures of recent positive selection on mtDNA of domestic horse were detected. Specifically, five amino acids in the four mitochondrial genes were identified as the targets of positive selection. Coalescentbased simulations imply that recent population expansion is the most probable explanation for the matrilineal population history for domestic horse. Our findings reveal a complex pattern of non-neutral evolution of the mitochondrial genome in the domestic horses.

Nonmedically indicated induction vs expectant treatment in term nulliparous women

OBJECTIVE

The purpose of this study was to compare maternal and neonatal outcomes in nulliparous women with nonmedically indicated inductions at term vs those expectantly treated.

STUDY DESIGN

Data were obtained from maternal and neonatal charts for all deliveries on randomly selected days across 25 US hospitals over a 3-year period. A low-risk subset of nulliparous women with vertex nonanomalous singleton gestations who delivered 38 0/7 to 41 6/7 weeks were selected. Maternal and neonatal outcomes for nonmedically indicated induction within each week were compared with women who did not undergo nonmedically indicated induction during that week. Multivariable analysis was used to adjust for hospital, maternal age, race/ethnicity, body mass index, cigarette use, and insurance status.

RESULTS

We found 31,169 women who met our criteria. Neonatal complications were either less frequent with nonmedically indicated induction or no different between groups. Nonmedically indicated induction was associated with less frequent peripartum infections (odds ratio [OR], 0.39; 95% confidence interval [CI], 0.16-0.98) at 38 weeks of gestation and less frequent third- and fourth-degree lacerations (OR, 0.60; 95% CI, 0.42-0.86) and less frequent peripartum infections (OR, 0.66; 95% CI, 0.49-0.90) at 39 weeks of gestation. Nonmedically indicated induction was associated with a longer admission-to-delivery time by approximately 3-4 hours and increased odds of cesarean delivery at 38 (OR, 1.50; 95% CI, 1.08-2.08) and 40 weeks (OR, 1.30; 95% CI, 1.15-1.46) of gestation.

CONCLUSION

At 39 weeks of gestation, nonmedically indicated induction is associated with lower maternal and neonatal morbidity than women who are expectantly treated.

A UK national survey of breast surgeons on primary endocrine therapy of early operable breast cancer

INTRODUCTION

A significant proportion of elderly breast cancer patients in the UK have no surgical treatment recorded and appear to be treated with primary endocrine therapy (PET) only. Despite this, PET remains one of the poorly studied areas in breast cancer therapy and very little is known about the practice of PET in the UK.

METHODS

A questionnaire comprising 14 questions relevant to PET was sent to 489 breast surgeons who were members of the UK Association of Breast Surgery and returned questionnaires were analysed.

RESULTS

Overall, 228 questionnaires (47%) were returned. The vast majority (93%) of surgeons who responded use PET in early operable breast cancer in elderly women unfit for surgery or owing to patient preference but 7% would recommend PET to fit elderly patients. Most (76%) use letrozole. The percentage of elderly patients treated with PET varied from <10% to 70% between surgeons. The majority (77%) of respondents had not formally audited the outcome of their PET patients and over 70% underestimated the expected survival of an 80-year-old woman.

CONCLUSIONS

Most UK breast surgeons use PET in elderly patients with surgically resectable breast cancer. While most use it in unfit, frail patients, a minority would treat even fit elderly women with PET. Most surgeons have not formally audited the outcome of their patients treated with PET and underestimate the expected survival of elderly patients, which might have an impact on their decision to offer PET rather than surgery.

Dependence and psychosis with 4-methylmethcathinone (mephedrone) use

'Legal highs' are recreational drugs sold over the internet and the so-called 'head shops' all over the UK. They are freely available to buy and use as they are not covered by the Misuse of Drugs Act 1971. Mephedrone (4-methylmethcathinone) was sold as a 'legal high' until 17 April 2010 when it was made a class B drug under the Misuse of Drugs Act 1971. Numerous deaths and self-harm has been associated with mephedrone use. Effects of mephedrone are reported to be empathogenic similar to 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) and stimulant properties similar to cocaine. Not much is known of the effects of mephedrone on mental health. We present a case of dependence and psychosis in a patient using mephedrone (4-methylmethcathinone). The patient needed inpatient hospital care, was treated with antipsychotic olanzapine and recovered well.

Vacuum infiltration of Petunia hybrida pollen with Agrobacterium tumefaciens to achieve plant transformation

 Genetic transformation of Petunia hybrida with a reporter gene and selectable marker gene (35S-bar) was achieved in similar frequencies by pollinating flowers with pollen vacuum-infiltrated with Agrobacterium tumefaciens or applying a drop of Agrobacterium suspension to the stigma immediately prior to pollination. Nine percent of the T₁, and 5% of the T₂ progeny germinated in nutrient medium with 3 mgl/l Basta^R. Polymerase chain reaction assays indicated that of the Basta^R-resistant plants, 66% of the T₁ plants, and 61% of the T₂ plants harboured the GUS gene. Histochemical assays showed that 10% of the putatively transformed T₁ plants and 5% of their progeny expressed GUS in leaf tissue, pistils and young anthers. Southern hybridization confirmed genomic integration of the bar gene in one to three places in selected T₁ and T₂ progeny.

The matrix metalloproteinase inhibitor batimastat inhibits angiogenesis in liver metastases of B16F1 melanoma cells

Matrix metalloproteinases (MMPs) have been shown to contribute functionally to tumor metastasis. MMP inhibitors are thus being assessed for clinical utility as anti-metastatic therapeutics. Batimastat (BB-94) is a synthetic MMP inhibitor that has been shown to inhibit tumor growth and metastasis in mice. Here we assessed the ability of batimastat to inhibit liver metastases of murine B16F1 cells, after injection of cells in mice via mesenteric vein to target the liver. We then determined which of the sequential steps in metastasis were affected by batimastat, in order to identify its mechanism of action in vivo. Intravital videomicroscopy was used to assess the effect on extravasation, and a 'cell accounting' procedure was used to determine the effect on initial survival of cells. Stereological quantification of functional blood vessels was used to determine the effect on tumor vascularity, thereby avoiding problems associated with immunohistochemical detection of liver sinusoidal endothelial cells. We found that batimastat (50 mg/kg i.p. 5 h prior to and after cell injection, daily thereafter) resulted in a 23% reduction in mean diameter of liver metastases (equivalent to a 54% reduction in tumor volume), while not reducing the number of metastases. Extravasation of cells from the liver circulation was not affected: at 8, 24 and 48 h after injection of cells, the same proportion of cells had extravasated from treated vs. control mice. Batimastat also did not inhibit early survival of cells. However, batimastat-treated mice had a significantly reduced percentage vascular volume within liver metastases, indicating inhibition of angiogenesis. This study demonstrates in vivo that the mechanism by which batimastat limits growth of B16F1 metastases in liver is not by affecting extravasation, but by inhibiting angiogenesis within metastases. This finding suggests that MMP inhibitors may be appropriate for use in patients with metastatic cells that have already extravasated in secondary sites.

Nucleotide and deduced amino acid sequence of the 3' end of the BYMV-MI genome

We have cloned and sequenced cDNA transcribed from the 3' 1,239 nucleotides of the genomic RNA of a Western Australian isolate (MI) of bean yellow mosaic potyvirus (BYMV). This sequence contains 246 nucleotides of the NIb (replicase) gene and 819 nucleotides representing the entire coding region of the viral coat protein gene, followed by a 3' non-coding region of 174 nucleotides. The coding region of the coat protein gene is identical in length (273 amino acids) to that already reported for other isolates of this virus. The sequence identities obtained for BYMV-MI and published sequences of BYMV isolates range between 85% and 92% for the coding region of the coat protein and 90% to 98% for the 3' non-coding region. Likewise, the region of the NIb gene sequenced shows 99% and 97% sequence identity in the deduced amino acid and the nucleotide sequences, respectively.

Synthesis and characterization of a biotinylated organophosphorus ester for detection and affinity purification of a brain serine esterase: neuropathy target esterase

We have synthesized a novel stable precursor, saligenin phosphorotrichloridate, which, on reaction with N-monobiotinyldiamines, generates a series of biotinylated covalent inhibitors of serine esterases. A homologue designated S9B [1-(saligenin cyclic phospho)-9-biotinyldiaminononane] was selected to allow detection and rapid isolation of neuropathy target esterase (NTE). This enzyme is the primary target site for those organophosphorus esters (OPs) which cause delayed neuropathy. NTE comprises about 0.03% of the total protein in brain microsomal fractions and has resisted purification attempts over many years. S9B is a potent progressive inhibitor of NTE esteratic activity (second-order rate constant 1.4 x 10(7) M-1.min-1). Incubation of S9B with brain microsomes led to specific covalent labelling of NTE as determined by detection of a biotinylated 155 kDa polypeptide on Western blots. Specificity of S9B labelling was further demonstrated by inhibition with the neuropathic OP mipafox. Biotinyl-NTE in SDS-solubilized S9B-labelled microsomes was adsorbed on to avidin-Sepharose and subsequently eluted, yielding a fraction enriched approx. 1000-fold in NTE by a single step with recoveries of 30%. Essentially pure NTE was obtained after separation from two endogenous biotinylated polypeptides (120 and 70 kDa) in avidin-Sepharose eluates by preparative SDS/PAGE. Other biotinylated saligenin phosphoramidates derived from the same precursor may be useful for detection and isolation of other serine esterases and proteinases.

Molecular characterisation of neuropathy target esterase: proteolysis of the [3H]DFP-labelled polypeptide

Neuropathy target esterase (NTE) in hen brain membranes can be labelled with tritiated di-isopropylfluorophosphate ([3H]DFP) and appears to be associated with a 155-kDa polypeptide. Using preparative SDS-PAGE, we have obtained preparations in which [3H]DFP-labelled NTE comprises 2% of the total protein. Further purification of the 155-kDa polypeptide has proved difficult. We therefore attempted to use proteases to excise smaller [3H]DFP-labelled fragments which might be more amenable to fractionation. V8 protease treatment generated a labelled fragment of about 16 kDa which could be fractionated on SDS-PAGE and contained tritium attached to both site X (putatively the active site serine) and site Z (the residue to which an isopropyl moiety is transferred during aging of [3H]DFP-inhibited NTE). Papain and thermolysin treatments generated a small labelled peptide (< 10 kDa) which could be fractionated on reverse-phase HPLC and in which tritium was attached to site X but not site Z. N-terminal sequencing of the thermolysin-generated peptide fraction indicated sample heterogeneity but also suggested that the active site of NTE may contain the serine esterase consensus sequence: Gly-Glu-Ser-Xxx-Gly.

A polymerase chain reaction assay for cucumber mosaic virus in lupin seeds

Seed is the main source of infection of narrow-leafed lupin (Lupinus angustifolius) crops by cucumber mosaic virus (CMV). The ELISA procedure is currently used for large-scale, routine testing of lupin seed samples, but a more sensitive, reliable and labour-saving assay is needed which detects levels of seed infection as low as 0.1%. A Polymerase Chain Reaction (PCR) using ground dry seed samples was developed for this purpose. Primers based on concensus sequences of eight published CMV coat protein cDNAs (RNA3) of CMV subgroups 1 and 2 were used. The assay involved (1) a reverse transcription step for cDNA synthesis and (2) amplification of a specific fragment (482-501 bp depending on the strain) by PCR. Two methods of extracting virus from infected lupin material were used: (i) a rapid procedure which was effective for samples with higher levels of infection, e.g. infected leaves and 20.5% infected seed; (ii) a phenol-chloroform procedure, which led to greater sensitivity, enabling reliable detection of 0.1% seed infection. It detected CMV in 16 commercial seed samples (0.1-8% seed infection) belonging to seven cultivars from 12 different localities. Both methods were suitable for routine testing of the flour derived from grinding dry seed. On dissection of infected seeds, CMV was detected in the cotyledons and embryo and usually in or on the testa. The PCR assay detected virus from both CMV subgroups, but only subgroup 2 was found in lupin seed samples. The two CMV subgroups can be distinguished by digestion of amplified DNA with the restriction enzyme EcoRI; only CMV strains of subgroup 2 are digested to yield two fragments of size 330 and 170 bp.

Autoantibodies to glycoprotein antigens mediate subacute demyelinating encephalomyelitis in the Lewis rat

Serum autoantibodies were induced in Lewis rats by immunization with a mixture of lentil lectin-binding glycoproteins isolated from bovine brain myelin. Intraperitoneal administration of 2-10 million syngeneic myelin basic protein-activated spleen cells to these rats led within 4-5 days to paralysis which, in most cases, persisted for several weeks. The major neuropathological features of the disease were numerous macrophages in both brain and spinal cord and large areas of demyelination, generally with axon preservation, particularly adjacent to the pial surfaces of the cord. This model is easily induced and will be useful for studies of demyelination and remyelination.