TidyTron: Reducing lab waste using validated wash-and-reuse protocols for common plasticware in Opentrons OT-2 lab robots

Every year biotechnology labs generate a combined total of ∼5.5 million tons of plastic waste. As the global bioeconomy expands, biofoundries will inevitably increase plastic consumption in-step with synthetic biology scaling. Decontamination and reuse of single-use plastics could increase sustainability and reduce recurring costs of biological research. However, throughput and variable cleaning quality make manual decontamination impractical in most instances. Automating single-use plastic cleaning with liquid handling robots makes decontamination more practical by offering higher throughput and consistent cleaning quality. However, open-source, validated protocols using low-cost lab robotics for effective decontamination of plasticware-facilitating safe reuse-have not yet been developed. Here we introduce and validate TidyTron: a library of protocols for cleaning micropipette tips and microtiter plates that are contaminated with DNA, E. coli, and S. cerevisiae. We tested a variety of cleaning solutions, contact times, and agitation methods with the aim of minimizing time and cost, while maximizing cleaning stringency and sustainability. We tested and validated these cleaning procedures by comparing fresh (first-time usage) versus cleaned tips and plates for contamination with cells, DNA, or cleaning solutions. We assessed contamination by measuring colony forming units by plating, PCR efficiency and DNA concentration by qPCR, and event counts and debris by flow cytometry. Open source cleaning protocols are available at https://github.com/PlantSynBioLab/TidyTron and hosted on a graphical user interface at https://jbryantvt.github.io/TidyTron/.

Strategies of nanoparticles integration in polymer fibers to achieve antibacterial effect and enhance cell proliferation with collagen production in tissue engineering scaffolds

Current design strategies for biomedical tissue scaffolds are focused on multifunctionality to provide beneficial microenvironments to support tissue growth. We have developed a simple yet effective approach to create core-shell fibers of poly(3-hydroxybuty-rate-co-3-hydroxyvalerate) (PHBV), which are homogenously covered with titanium dioxide (TiO2) nanoparticles. Unlike the blend process, co-axial electrospinning enabled the uniform distribution of nanoparticles without the formation of large aggregates. We observed 5 orders of magnitude reduction in Escherichia coli survival after contact with electrospun scaffolds compared to the non-material control. In addition, our hybrid cores-shell structure supported significantly higher osteoblast proliferation after 7 days of cell culture and profound generation of 3D networked collagen fibers after 14 days. The organic-inorganic composite scaffold produced in this study demonstrates a unique combination of antibacterial properties and increased bone regeneration properties. In summary, the multifunctionality of the presented core-shell cPHBV+sTiO2 scaffolds shows great promise for biomedical applications.

Identification of potential Auxin Response Candidate genes for soybean rapid canopy coverage through comparative evolution and expression analysis

Glycine max, soybean, is an abundantly cultivated crop worldwide. Efforts have been made over the past decades to improve soybean production in traditional and organic agriculture, driven by growing demand for soybean-based products. Rapid canopy cover development (RCC) increases soybean yields and suppresses early-season weeds. Genome-wide association studies have found natural variants associated with RCC, however causal mechanisms are unclear. Auxin modulates plant growth and development and has been implicated in RCC traits. Therefore, modulation of auxin regulatory genes may enhance RCC. Here, we focus on the use of genomic tools and existing datasets to identify auxin signaling pathway RCC candidate genes, using a comparative phylogenetics and expression analysis approach. We identified genes encoding 14 TIR1/AFB auxin receptors, 61 Aux/IAA auxin co-receptors and transcriptional co-repressors, and 55 ARF auxin response factors in the soybean genome. We used Bayesian phylogenetic inference to identify soybean orthologs of Arabidopsis thaliana genes, and defined an ortholog naming system for these genes. To further define potential auxin signaling candidate genes for RCC, we examined tissue-level expression of these genes in existing datasets and identified highly expressed auxin signaling genes in apical tissues early in development. We identified at least 4 TIR1/AFB, 8 Aux/IAA, and 8 ARF genes with highly specific expression in one or more RCC-associated tissues. We hypothesize that modulating the function of these genes through gene editing or traditional breeding will have the highest likelihood of affecting RCC while minimizing pleiotropic effects.

AssemblyTron: flexible automation of DNA assembly with Opentrons OT-2 lab robots

As one of the newest fields of engineering, synthetic biology relies upon a trial-and-error Design-Build-Test-Learn (DBTL) approach to simultaneously learn how a function is encoded in biology and attempt to engineer it. Many software and hardware platforms have been developed to automate, optimize and algorithmically perform each step of the DBTL cycle. However, there are many fewer options for automating the build step. Build typically involves deoxyribonucleic acid (DNA) assembly, which remains manual, low throughput and unreliable in most cases and limits our ability to advance the science and engineering of biology. Here, we present AssemblyTron, an open-source Python package to integrate j5 DNA assembly design software outputs with build implementation in Opentrons liquid handling robotics with minimal human intervention. We demonstrate the versatility of AssemblyTron through several scarless, multipart DNA assemblies, beginning from fragment amplification. We show that AssemblyTron can perform polymerase chain reactions across a range of fragment lengths and annealing temperatures by using an optimal annealing temperature gradient calculation algorithm. We then demonstrate that AssemblyTron can perform Golden Gate and homology-dependent in vivo assemblies (IVAs) with comparable fidelity to manual assemblies by simultaneously building four four-fragment assemblies of chromoprotein reporter expression plasmids. Finally, we used AssemblyTron to perform site-directed mutagenesis reactions via homology-dependent IVA also achieving comparable fidelity to manual assemblies as assessed by sequencing. AssemblyTron can reduce the time, training, costs and wastes associated with synthetic biology, which, along with open-source and affordable automation, will further foster the accessibility of synthetic biology and accelerate biological research and engineering.

P1419 Sex-related differences in cardiac remodeling in health and hypertension

Funding Acknowledgements

National Medical Research Council

OnBehalf

National Heart Centre Singapore

BACKGROUND

Adverse cardiac remodelling is associated with worse cardiovascular outcomes. Development of left ventricular hypertrophy (defined as increased myocardial mass) is a complex process mediated by myocardial wall thickening and/or ventricular dilatation. Sex-related differences in the relationship between myocardial mass and wall thickening/ventricular dilatation have not been well-described.

PURPOSE

We examine differences in determinants and patterns of cardiac remodeling between males and females.

METHODS

Comprehensive cardiovascular magnetic resonance imaging was performed in 1006 participants: 316 healthy volunteers (50% males, 46 ± 14 years) and 690 asymptomatic hypertensive patients (60% males, 57 ± 11 years). Myocardial mass, ventricular volumes and maximal myocardial wall thickness (across 16 myocardial segments) were measured using standardized contouring techniques. Clinically relevant variables (age, weight, height, and adiposity) that demonstrated significant univariate association with myocardial mass (P < 0.05) were selected in the multivariable linear regression model using the forward approach.

RESULTS

Increased body weight, lower body fat composition and higher systolic blood pressures were independently associated with increased myocardial mass in healthy volunteers (males and females) and hypertensive females. In hypertensive males, only increased body weight and elevated systolic blood pressure were independently associated with increased myocardial mass.

The association between myocardial mass and ventricular volumes was almost identical between males and females (P = 0.65 for interaction; Figure). Conversely, there was a significant gender-related difference in the association between wall thickness and myocardial mass after adjusting for potential confounders (P < 0.001 for interaction). Concentric remodeling was initially more evident in males; but further with increase, myocardial mass was associated with greater concentric remodeling in females (Figure). Similar results were observed when analyses were performed separately in healthy volunteers and hypertensive patients.

CONCLUSION

There were sex-related differences in concentric remodeling at progressive stages of myocardial hypertrophy that may explain the higher prevalence of heart failure with preserved ejection fraction reported in females.

Abstract P1419 Figure

Facility management in Qatar: current state, perceptions and recommendations

Purpose

This paper aims to identify the current challenges and opportunities faced by the facility managers (FMs) in Doha, Qatar.

Design/methodology/approach

Researchers queried 40 FMs about their experience working in Qatar, using interviews and workshops.

Findings

Comments gathered followed general patterns. Participants expressed appreciation for their work, but also concern about cultural challenges they faced managing facilities in the region. In general, it was agreed that the low cost of water and energy in Qatar is one of the largest obstacles to conserving resources; however, current consumption is not sustainable.

Research limitations/implications

The sensitive nature of this study made strict demands on the research team to maintain participant anonymity during data collection and reporting. This sensitivity also limited the sample size; a larger sample size for future research would support greater generalizability.

Social implications

Qatar is taking steps to reduce its per capita carbon footprint and energy use, which is among the highest in the world. However, there appears to be a disconnect between Qatar’s expressed intentions and its actions with respect to facility management. To ensure that Qatar manages resources more efficiently, participants recommended that reduced energy use standards be adopted and legally mandated. This action would address many of the challenges, incentivize increased qualifications and training of FM professionals working in Qatar and encourage improvement of the long-term performance of buildings which are energy drains and heavy contributors to greenhouse gas emissions.

Originality/value

Prior to this study, little has been published about current practices of facility management in Doha, Qatar, and the challenges and opportunities that FMs face in this region.

Initiation of DNA replication: functional and evolutionary aspects

BACKGROUND

The initiation of DNA replication is a very important and highly regulated step in the cell division cycle. It is of interest to compare different groups of eukaryotic organisms (a) to identify the essential molecular events that occur in all eukaryotes, (b) to start to identify higher-level regulatory mechanisms that are specific to particular groups and (c) to gain insights into the evolution of initiation mechanisms.

SCOPE

This review features a wide-ranging literature survey covering replication origins, origin recognition and usage, modification of origin usage (especially in response to plant hormones), assembly of the pre-replication complex, loading of the replisome, genomics, and the likely origin of these mechanisms and proteins in Archaea.

CONCLUSIONS

In all eukaryotes, chromatin is organized for DNA replication as multiple replicons. In each replicon, replication is initiated at an origin. With the exception of those in budding yeast, replication origins, including the only one to be isolated so far from a plant, do not appear to embody a specific sequence; rather, they are AT-rich, with short tracts of locally bent DNA. The proteins involved in initiation are remarkably similar across the range of eukaryotes. Nevertheless, their activity may be modified by plant-specific mechanisms, including regulation by plant hormones. The molecular features of initiation are seen in a much simpler form in the Archaea. In particular, where eukaryotes possess a number of closely related proteins that form 'hetero-complexes' (such as the origin recognition complex and the MCM complex), archaeans typically possess one type of protein (e.g. one MCM) that forms a homo-complex. This suggests that several eukaryotic initiation proteins have evolved from archaeal ancestors by gene duplication and divergence.

Study of the scan uniformity from an i-CAT cone beam computed tomography dental imaging system

OBJECTIVES

As part of an ongoing programme to improve diagnosis and treatment planning relevant to implant placement, orthodontic treatment and dentomaxillofacial surgery, a study has been made of the spatial accuracy and density response of an i-CAT, a cone beam CT (CBCT) dental imaging system supplied by Imaging Sciences International Inc.

METHODS

Custom-made phantoms using acrylic sheet and water were used for measurements on spatial accuracy, density response and noise. The measurements were made over a period of several months on a clinical machine rather than on a machine dedicated to research.

RESULTS

Measurements on a precision grid showed the spatial accuracy to be universally within the tolerance of +/-1 pixel. The density response and the noise in the data were found to depend strongly on the mass in the slice being scanned.

CONCLUSIONS

The density response was subject to two effects. The first effect changes the whole slice uniformly and linearly depends on the total mass in the slice. The second effect exists when there is mass outside the field of view, dubbed the "exo-mass" effect. This effect lowers the measured CT number rapidly at the scan edge furthest from the exo-mass and raises it on the adjacent edge. The noise also depended quasi-linearly on the mass in the slice. Some general performance rules were drafted to describe these effects and a preliminary correction algorithm was constructed.

Presurgical, ultrasound-guided anchor-wire marking of impalpable cervical lymph nodes

This case illustrates the surgical use of wire localization, a well tried technique from a different field of surgery, in the removal of an ultrasound-detected, impalpable deep lower cervical lymph node in a high-risk patient. A localization needle with an echogenic tip was placed freehand under ultrasound guidance, immediately before surgery. The imaging and marking of the impalpable cervical lymph node resulted in a precise surgical dissection and a reduction in operating time whilst minimizing risks to the patient and staff.

Both chloroplastic and cytosolic phosphoglycerate kinase isozymes are present in the pea leaf nucleus

Phosphoglycerate kinase (EC 2.7.2.3) occurs in chloroplasts, cytosol, and nuclei in higher plants. Immunocytolocalization experiments with isozyme-specific antibodies indicate that both the chloroplastic and the cytosolic forms of the enzyme are present in the pea (Pisum sativum L.) leaf nucleus.

Cloning and expression of cytosolic phosphoglycerate kinase from pea (Pisum sativum L.)

In common with several other respiratory and photosynthetic enzymes, a sub-population of cytosolic phosphoglycerate kinase (PGK) occurs in the nucleus in pea leaves and shoots. The full-length cDNA encoding pea cytosolic PGK has been cloned and sequenced, revealing not only the PGK 'signature' but also a nuclear localization signal (NLS). A translational fusion of PGK and GFP was used to transform tobacco BY-2 cells resulting in GFP locating to the cell nuclei.

Genes encoding two essential DNA replication activation proteins, Cdc6 and Mcm3, exhibit very different patterns of expression in the tobacco BY-2 cell cycle

Very little is known about the expression patterns in plants of genes that encode proteins involved in the initiation of DNA replication. Partial cDNA sequences that encode Cdc6 and Mcm3 in tobacco have been isolated. The sequences were used as probes in northern blots which suggested that, in the cell cycle of synchronized tobacco BY-2 cells, expression of CDC6 is confined to late G(1) and S-phase whereas the expression of MCM3 is not confined to any particular cell cycle phase. These data were confirmed and extended by real-time PCR measurements of mRNA abundance through the cell cycle. CDC6 exhibits a very clear peak of expression in S-phase whereas MCM3, expressed at a much lower level than CDC6, is not cell-cycle-regulated. These patterns of cell cycle gene expression resemble those found in the fission yeast Schizosaccharomyces pombe rather than those in budding yeast or mammalian cells.

Online sales: profit without question

OBJECTIVES

To examine the ease with which underage smokers can purchase cigarettes online using money orders and to evaluate the effectiveness of internet filtering programs in blocking access to internet cigarette vendors (ICVs).

DESIGN

Four young people purchased 32 money orders using 32 different names to buy one carton of cigarettes for each named individual. Each money order was subsequently mailed to a different ICV in the USA. No age related information accompanied these online orders. Two internet filtering programs ("Bess" and filtertobacco.org) were tested for their relative efficacy in blocking access to ICV sites.

RESULTS

Of the 32 orders placed, four orders never reached the intended ICV. Of the remaining 28 orders, 20 (71%) were filled despite a lack of age verification. Only four (14%) of the orders received were rejected because they lacked proof of age. "Bess" blocked access to 84% and filtertobacco.org to 94% of the ICV sites.

CONCLUSIONS

Although underage smokers can easily purchase cigarettes online using money orders, access to these sites can be largely blocked if appropriate filtering devices are installed.

Fission yeast Cdc23 interactions with DNA replication initiation proteins

Schizosaccharomyces pombe Cdc23 is an essential DNA replication protein, conserved in eukaryotes and functionally homologous with Saccharomyces cerevisiae Dna43 (Mcm10). We sought evidence for interactions between Cdc23 and the MCM2-7 complex, a component of both the pre-replicative complex and the replication fork. Cdc23 shows genetic interactions with four MCM subunits: cdc23-M36 and cdc23-1E2 alleles both show synthetic phenotypes with mcm2 (cdc19-P1) and mcm6 (mis5-268), and cdc23-M36 is synthetically lethal with mcm4 (cdc21-K46) and with mcm5 (nda4-108). The wild-type cdc23 gene on multicopy plasmids can partially suppress temperature-dependent defects in mcm5 (nda4-108). Two-hybrid analysis demonstrates interactions at the protein-protein level between Cdc23 and Mcm4, Mcm5 and Mcm6. Cdc23 also interacts with four subunits of the Schizosaccharomyces pombe origin recognition complex (ORC) in yeast two-hybrid assay: Orc1, Orc2, Orc5 and Orc6. We found no evidence for interaction between Cdc23 and the MCM recruitment factor Cdc18 (the homologue of Saccharomyces cerevisiae Cdc6). Unlike Cdc18, Cdc23 mRNA shows no significant fluctuation in level through the cell cycle. These data suggest that fission yeast Cdc23 is an MCM-associated factor which has a role in the initiation of DNA replication.

Endoreduplication is not inhibited but induced by aphidicolin in cultured cells of tobacco

Endoreduplication is a common process in plants that allows cells to increase their DNA content. In the tobacco cell cultures studied in this work it can be induced by simple hormone deprivation. Mesophyll protoplast-derived cells cultured in the presence of NAA (auxin) and BAP (cytokinin) keep on dividing, while elongation and concomitant DNA endoreduplication are induced and maintained in a medium containing only NAA. If aphidicolin is given to the two types of culture, no effect is observed on elongating, endoreduplicating cells. However, the cells programmed for division switch to elongation and DNA endoreduplication. Thus aphidicolin, an inhibitor of the replicative DNA polymerases, alpha and delta, does not inhibit endoreduplication, and furthermore actually induces it when the mitotic cell cycle is blocked. DNA duplication and cell growth can only be completely blocked if ddTTP, an inhibitor of DNA polymerase-beta, is given together with aphidicolin. This result implies that an aphidicolin-resistant DNA polymerase, such as the repair-associated DNA polymerase-beta, can mediate DNA synthesis during endoreduplication and can substitute for polymerases-alpha and -delta when the latter are inhibited. Similar results are obtained in cultures of the BY-2 cell line by withdrawing auxins from the culture medium. In this cell line endoreduplication is induced only in a small proportion of the cells. A greater proportion of the cells are blocked in the G(2) phase of the cell cycle.

A comparison of radiographic foot measurements taken in two different positions

The purpose of this study was to ascertain if positioning of the feet for radiographic assessment produces significant variations in measured angles, and if measurements taken from radiographs taken on two separate occasions are reproducible. Weightbearing x-rays were taken of both feet of ten male healthy subjects in two standardized positions: 1) the angle and base of gait and 2) the feet together and straight-ahead positions. The radiographs were repeated 2 weeks later. The results failed to demonstrate significant differences of radiographic measurements between the two specific foot-positioning methods. No significant differences were found between radiographic measurements of normal feet taken on different occasions. A strong correlation of the repeated measures suggests that weightbearing foot radiographs can be reliably reproduced.

Origins and complexes: the initiation of DNA replication

Eukaryotic DNA is organized for replication as multiple replicons. DNA synthesis in each replicon is initiated at an origin of replication. In both budding yeast, Saccharomyces cerevisiae and fission yeast, Schizosaccharomyces pombe, origins contain specific sequences that are essential for initiation, although these differ significantly between the two yeasts with those of S. pombe being more complex then those of S. cerevisiae. However, it is not yet clear whether the replication origins of plants contain specific essential sequences or whether origin sites are determined by features of chromatin structure. In all eukaryotes there are several biochemical events that must take place before initiation can occur. These are the marking of the origins by the origin recognition complex (ORC), the loading onto the origins, in a series of steps, of origin activation factors including the MCM proteins, and the initial denaturation of the double helix to form a replication "bubble". Only then can the enzymes that actually initiate replication, primase and DNA polymerase-alpha, gain access to the template. In many cells this complex series of events occurs only once per cell cycle, ensuring that DNA is not re-replicated within one cycle. However, regulated re-replication of DNA within one cell cycle (DNA endoreduplication) is relatively common in plants, indicating that the "once-per-cycle" controls can be overridden.

A novel DNA-binding protein associated with DNA polymerase-alpha in pea stimulates polymerase activity on infrequently primed templates

A 42 kDa DNA-binding protein is associated with DNA polymerase-alpha-primase in pea (Pisum sativum). In a previous publication it was shown that the protein has strong preference for ds-ss junctions in DNA, including the cohesive termini generated by restriction endonucleases. In this paper it is shown that when the DNA-binding protein is added back to polymerase-primase, the protein stimulates the activity of the polymerase. The stimulation is particularly marked when M13 DNA, primed with a single sequencing primer or primed with oligoribonucleotides by the polymerase's associated primase activity, is used as a template. The stimulation of polymerase activity is not caused by an increase in processivity. These data lead to the suggestion that the 42 kDa DNA-binding protein is a primer-recognition protein.

High-field DNP and ENDOR with a novel multiple-frequency resonance structure

We describe a new triply tuned (e(-), (1)H, and (13)C) resonance structure operating at an electron Larmor frequency of 139.5 GHz for dynamic nuclear polarization (DNP) and electron nuclear double-resonance (ENDOR) experiments. In contrast to conventional double-resonance structures, the body of the microwave cavity simultaneously acts as a NMR coil, allowing for increased efficiency of radiofrequency irradiation while maintaining a high quality factor for microwave irradiation. The resonator design is ideal for low-gamma-nuclei ENDOR, where sensitivity is limited by the fact that electron spin relaxation times are on the order of the RF pulse lengths. The performance is demonstrated with (2)H ENDOR on a standard perdeuterated bis-diphenylene-phenyl-allyl stable radical. In DNP experiments, we show that the use of this resonator, combined with a low microwave power setup (17 mW), leads to significantly higher (1)H signal enhancement (epsilon approximately 400 +/- 50) than previously achieved at 5-T fields. The results emphasize the importance of optimizing the microwave B(1) field by improving either the quality factor of the microwave resonator or the microwave power level.

Pulsed electron-nuclear double resonance (ENDOR) at 140 GHz

We describe a spectrometer for pulsed ENDOR at 140 GHz, which is based on microwave IMPATT diode amplifiers and a probe consisting of a TE011 cavity with a high-quality resonance circuit for variable radiofrequency irradiation. For pulsed EPR we obtain an absolute sensitivity of 3x10(9) spins/Gauss at 20 K. The performance of the spectrometer is demonstrated with pulsed ENDOR spectra of a standard bis-diphenylene-phenyl-allyl (BDPA) doped into polystyrene and of the tyrosyl radical from E. coli ribonucleotide reductase (RNR). The EPR spectrum of the RNR tyrosyl radical displays substantial g-anisotropy at 5 T and is used to demonstrate orientation-selective Davies-ENDOR.

Novel DNA-binding characteristics of a protein associated with DNA polymerase-alpha in pea

DNA polymerase-alpha-primase may be isolated from pea shoot tip cells as a large (1.25 x 10(6) Da) multi-protein complex. The complex exhibits several enzyme activities and also binds to DNA. One of the DNA-binding activities has been purified as a 42 kDa polypeptide. The binding of this polypeptide to linear DNA fragments and to open circular plasmids has been studied by electron microscopy. The protein binds to restriction enzyme-generated cohesive ends of linear fragments and also exhibits some interstitial binding. Binding at the ends of linear molecules is very markedly reduced if the molecules are previously treated with S1 nuclease. The protein also binds to open circular plasmids; the number of binding sites is increased by exposing the plasmids to gamma-irradiation prior to the DNA-protein interaction. In these experiments, the number of protein units bound is directly related to the radiation dose. With both linear and open circular molecules, binding of the protein to the DNA leads to an apparent shortening of the DNA molecule. These observations, taken with the finding that the protein does not bind to completely single-stranded DNA, lead to the suggestion that the protein binds to double-stranded-single-stranded (ds-ss) junctions in DNA and that binding causes the DNA to wrap round the protein.

Effect of blood donation on the establishment of normal ranges of lymphocyte subsets

BACKGROUND

Absolute counts of CD4+ T-lymphocytes are used in the management of patients with human immunodeficiency virus infection. Low absolute counts of CD3+CD4+ cells have also been observed in healthy people--a phenomenon called idiopathic CD4 lymphocytopenia. It is common practice for normal ranges for lymphocyte subsets to be derived from samples taken from blood donors.

STUDY DESIGN AND METHODS

A sample of EDTA blood was taken through the donation line tubing, after donation from 565 blood donors in Sydney, Australia, who were selected from a range of age groups. An additional 12 donors provided a predonation sample as well as a postdonation sample. Hematologic assays were performed on two analyzers. Samples were stained for CD3, CD4, CD8, CD19, and CD56 and analyzed on a flow cytometer.

RESULTS

Three donors were found to have absolute CD3+CD4+ counts < 300 cells per microL. The percentage of CD3+CD4+ cells was found to increase with age. Both the percentage and the absolute count of CD3+CD8+ cells decreased with age, which resulted in an increased CD4:CD8 ratio with age. Men had consistently higher absolute counts of CD3-CD56+ cells than women. The 12 additional donors all had greater percentages of CD3+CD4+ cells and lower absolute counts for CD3+, CD3+CD4+, CD3+CD8+, CD19+ and CD3-CD56+ cells after donation than they had before donation (p < 0.001).

CONCLUSION

It is not satisfactory to base normal ranges for lymphocyte subsets on donor blood, from which the blood sample has been obtained after donation.

Coordinator's report on the flow cytometric analysis of the Rh antibodies

One hundred and four IgG monoclonal antibodies with specificity within the Rh Blood Group System were evaluated by flow cytometry as part of the Third International Workshop. Standardisation of data to permit interlaboratory comparison of antibody binding was achieved by adherence to a standard red blood cell staining protocol, defined control cells and a standard FITC-labelled antibody. In addition, calibration standards were provided to permit the calculation of Molecules of Equivalent Soluble Fluorochrome (MESF) values from the mean channel fluorescence. For the majority of anti-D antibodies mean MESF values obtained with D positive cells were far higher than with the negative controls (D negative cells), with D variants having intermediate although very varied MESFs. In general MESF values obtained with non anti-D antibodies were less than for the anti-D antibodies although some of the anti-E antibodies were very strong. The highest MESF values were obtained with an anti-CD antibody.

Protease-modified erythrocytes: CD55 and CD59 deficient PNH-like cells

The increased susceptibility to homologous complement in paroxysmal nocturnal haemoglobinuria (PNH) is known to be associated with the deficiency of the membrane complement inhibitors CD59 and CD55. Proteases have been used in this study to modify normal human RBC to complement sensitive PNH-like cells. To investigate the protective role of CD59 and CD55, the relationship between the content of CD59 and CD55 and the complement susceptibility of the PNH-like cells has been determined. The differential resistance of the enzyme-treated RBC to complement-mediated injury was measured by acidified serum lysis. Pronase-treated erythrocytes lacked both CD59 and CD55 and were very susceptible to complement-mediated lysis. Papain treatment of RBC reduced the CD55 content but did not affect CD59 and induced slight susceptibility to complement-mediated lysis. Trypsin treatment of RBC destroyed 80% of CD59, had little effect on CD55 (unless incubation was extended) and slightly increased susceptibility to lysis. Thus, partial CD55 and CD59 activity was sufficient to protect cells from complement-mediated lysis. In the reactive lysis assay, anti-CD55 and anti-CD59 induced haemolysis, anti-CD59 having the more pronounced effect. Lysis was enhanced when RBC were treated by both antibodies simultaneously.

Six monoclonal antibodies to the CD59 antigen

CD59 defines an N-glycosylated glycoprotein expressed on various hemopoietic cells. It is anchored to the cell membrane by a glycosylpbospbatidylinositol linkage and restricts the action of homologous complement. Monoclonal antibodies 2/24, 182, Fib75.1, BRIC 229, MEM-43, and YTH 53.1 were compared by immunoblotting against normal erythrocyte ghosts. All six stained a diffuse band of 17-25 kDa, but BRIC 229 also detected bands at 35 and 80 kDa. 2/24 reacts with all red blood cells (RBCs) tested, including Rhnull; Ob; ii; Ko; FY:-1,-2,-3; JK:-1,-2,-3; S-s-U-; p; CO:-1,-2; Yt(a-); Jr(a-); Vel-; At(a-); Cr(a-); GE:-2,-3; Wr(a+b+ MkMk; Jo(a-); and Lan-. 2-aminoethylisotbiouronium bromide treatment of erythrocytes destroyed blotting and serologic reactivity of all six antibodies. Pronase treatment reduced serologic reactivity and blotting ability of all antibodies except BRlC 229. Reactivity of all six antibodies was reduced with RBCs from paroxysmal nocturnal hemoglobinuria patients. Flow cytometric analysis was used to demonstrate that 182, Fib75.1, BRIC 229, YTH 53.1, and MEM-43 competitively inhibited the binding of 2/24 to RBCs, thus demonstrating that all six antibodies detect epitopes on the same molecule.

New monoclonal antibodies in CD59: use for the analysis of peripheral blood cells from paroxysmal nocturnal haemoglobinuria (PNH) patients and for the quantitation of CD59 on normal and decay accelerating factor (DAF)-deficient erythrocytes

CD59 is a widely expressed cell surface glycosylphosphatidylinositol (GPI)-linked glycoprotein which acts as an inhibitor of the assembly of the membrane attack complex of autologous complement. Four new monoclonal antibodies to CD59 (2/24, 1B2, BRIC 229, BRIC 257) are described. Competitive binding experiments using these antibodies, two known CD59 antibodies (MEM-43, YTH 53.1) and a previously described antibody LICR-LON-Fib75.1 demonstrated that all seven antibodies see related epitopes on human erythrocyte CD59. In common with other GPI-linked proteins, CD59 (as defined by antibody 2/24) was sensitive to treatment with phosphatidylinositol-specific phospholipase C (PI-PLC) on lymphocytes and monocytes but not on erythrocytes. Flow cytometric analysis using antibody 2/24 identified two populations (CD59 positive and CD59 deficient) of lymphocytes, monocytes and erythrocytes in peripheral blood from a patient with paroxysmal nocturnal haemoglobinuria (PNH). The abundance of CD59 on normal erythrocytes was determined as 21,000 copies/cell when radioiodinated BRIC 229 was used. Other CD59 antibodies gave values of 10,000 (IF5) and 15,000 (2/24) against the same target cells. Radioiodinated Fab fragments of BRIC 229 gave a value of 39,000 copies/cell. Erythrocytes from two individuals with a rare inherited deficiency of decay accelerating factor (DAF), known as the Inab phenotype, expressed normal levels of CD59.

Detection of CaMV gene I and gene VI protein products in vivo using antisera raised to COOH-terminal β-galactosidase fusion proteins

Specific antisera were prepared to the inclusion body protein (gene VI product) and the gene I product of cauliflower mosaic virus (CaMV). Translational fusions between the lacZ gene and gene VI or gene I were constructed by cloning the relevant DNA fragments into the expression vectors pUR290, pUR291 or pUR292. Large amounts of fusion protein were synthesized when the inserted DNA fragment was in frame with the lacZ gene of the expression vector. These fusion proteins were used to raise specific antisera to gene VI and gene I proteins of CaMV. Antiserum to the gene VI product detected a range of proteins in crude extracts and in a subcellular fraction enriched for virus inclusion bodies. This range of proteins was further shown to be related to gene VI by Staphylococcus aureus V8 partial proteolysis. Antiserum to the gene I product detected viral specific proteins of 46, 42 and 38 K in preparations of CaMV replication complexes from infected plants but not in any other subcellular fraction.