A haploid diamondback moth (Plutella xylostella L.) genome assembly resolves 31 chromosomes and identifies a diamide resistance mutation

The diamondback moth, Plutella xylostella (L.), is a highly mobile brassica crop pest with worldwide distribution and can rapidly evolve resistance to insecticides, including group 28 diamides. Reference genomes assembled using Illumina sequencing technology have provided valuable resources to advance our knowledge regarding the biology, origin and movement of diamondback moth, and more recently with its sister species, Plutella australiana. Here we apply a trio binning approach to sequence and annotate a chromosome level reference genome of P. xylostella using PacBio Sequel and Dovetail Hi-C sequencing technology and identify a point mutation that causes resistance to commercial diamides. A P. xylostella population collected from brassica crops in the Lockyer Valley, Australia (LV-R), was reselected for chlorantraniliprole resistance then a single male was crossed to a P. australiana female and a hybrid pupa sequenced. A chromosome level 328 Mb P. xylostella genome was assembled with 98.1% assigned to 30 autosomes and the Z chromosome. The genome was highly complete with 98.4% of BUSCO Insecta genes identified and RNAseq informed protein prediction annotated 19,002 coding genes. The LV-R strain survived recommended field application doses of chlorantraniliprole, flubendiamide and cyclaniliprole. Some hybrids also survived these doses, indicating significant departure from recessivity, which has not been previously documented for diamides. Diamide chemicals modulate insect Ryanodine Receptors (RyR), disrupting calcium homeostasis, and we identified an amino acid substitution (I4790K) recently reported to cause diamide resistance in a strain from Japan. This chromosome level assembly provides a new resource for insect comparative genomics and highlights the emergence of diamide resistance in Australia. Resistance management plans need to account for the fact that resistance is not completely recessive.

Receptor homodimerization plays a critical role in a novel dominant negative P2RY12 variant identified in a family with severe bleeding

Essentials Three dominant variants for the autosomal recessive bleeding disorder type-8 have been described. To date, there has been no phenotype/genotype correlation explaining their dominant transmission. Proline plays an important role in P2Y12R ligand binding and signaling defects. P2Y12R homodimer formation is critical for the receptor function and signaling.

SUMMARY

Background Although inherited platelet disorders are still underdiagnosed worldwide, advances in molecular techniques are improving disease diagnosis and patient management. Objective To identify and characterize the mechanism underlying the bleeding phenotype in a Caucasian family with an autosomal dominant P2RY12 variant. Methods Full blood counts, platelet aggregometry, flow cytometry and western blotting were performed before next-generation sequencing (NGS). Detailed molecular analysis of the identified variant of the P2Y12 receptor (P2Y12R) was subsequently performed in mammalian cells overexpressing receptor constructs. Results All three referred individuals had markedly impaired ADP-induced platelet aggregation with primary wave only, despite normal total and surface P2Y12R expression. By NGS, a single P2RY12:c.G794C substitution (p.R265P) was identified in all affected individuals, and this was confirmed by Sanger sequencing. Mammalian cell experiments with the R265P-P2Y12R variant showed normal receptor surface expression versus wild-type (WT) P2Y12R. Agonist-stimulated R265P-P2Y12R function (both signaling and surface receptor loss) was reduced versus WT P2Y12R. Critically, R265P-P2Y12R acted in a dominant negative manner, with agonist-stimulated WT P2Y12R activity being reduced by variant coexpression, suggesting dramatic loss of WT homodimers. Importantly, platelet P2RY12 cDNA cloning and sequencing in two affected individuals also revealed three-fold mutant mRNA overexpression, decreasing even further the likelihood of WT homodimer formation. R265 located within extracellular loop 3 (EL3) is one of four residues that are important for receptor functional integrity, maintaining the binding pocket conformation and allowing rotation following ligand binding. Conclusion This novel dominant negative variant confirms the important role of R265 in EL3 in the functional integrity of P2Y12R, and suggests that pathologic heterodimer formation may underlie this family bleeding phenotype.

Mean platelet diameter measurements to classify inherited thrombocytopenias

INTRODUCTION

Mean platelet volume (MPV) assists the differential diagnosis of inherited thrombocytopenia (IT) but lacks standardisation and varies between automated analysers. Classification of IT based on mean platelet diameter (MPD) has been proposed by an international collaborative study but has not been validated.

METHODS

To assess the applicability of MPD to classify forms of IT, digital images of blood films from patients with established genetic causes for IT were generated, and the MPD measured (ZEISS Axio-scanner and Image J software) by a blinded reviewer. Comparison was made to the proposed classification system.

RESULTS

Mean platelet volume was measured in thrombocytopenia with different genetic aetiologies, bilallelic BSS (bBSS) (n = 1), monoallelic BSS (mBSS) (n = 2), MYH9-related disorders (MYH9-RD) (n = 11), GFI1B-related thrombocytopenia (RT) (n = 15), FLI1-RT (n = 2), TUBB1-RT (n = 3), ITGA2B/ITGB3-RT (n = 1), RUNX1-RT (n = 2) and controls (n = 54). bBSS and 82% of MYH9-RD samples had MPD >4 μm which correlated with "IT with giant platelets." Only 55% of samples expected in the "large platelet group" had MPD meeting the classification cut-off (MPD >3.2 μm). FLI1-RT MPD were significantly larger than expected whilst ITGA2B/ITGB3-RT MPD were smaller than proposed. MPD in FPD/AML were "normal."

CONCLUSION

Platelet MPD measurements are a useful guide to classify IT, but the time taken to record measurements may limit clinical applicability.

Thrombocytopenia and CD34 expression is decoupled from α-granule deficiency with mutation of the first growth factor-independent 1B zinc finger

Essentials The phenotypes of different growth factor-independent 1B (GFI1B) variants are not established. GFI1B variants produce heterogeneous clinical phenotypes dependent on the site of mutation. Mutation of the first non-DNA-binding zinc-finger causes a mild platelet and clinical phenotype. GFI1B regulates the CD34 promoter; platelet CD34 expression is an indicator of GFI1B mutation.

SUMMARY

Background Mutation of the growth factor-independent 1B (GFI1B) fifth DNA-binding zinc-finger domain causes macrothrombocytopenia and α-granule deficiency leading to clinical bleeding. The phenotypes associated with GFI1B variants disrupting non-DNA-binding zinc-fingers remain uncharacterized. Objectives To determine the functional and phenotypic consequences of GFI1B variants disrupting non-DNA-binding zinc-finger domains. Methods The GFI1B C168F variant and a novel GFI1B c.2520 + 1_2520 + 8delGTGGGCAC splice variant were identified in four unrelated families. Phenotypic features, DNA-binding properties and transcriptional effects were determined and compared with those in individuals with a GFI1B H294 fs mutation of the fifth DNA-binding zinc-finger. Patient-specific induced pluripotent stem cell (iPSC)-derived megakaryocytes were generated to facilitate disease modeling. Results The DNA-binding GFI1B variant C168F, which is predicted to disrupt the first non-DNA-binding zinc-finger domain, is associated with macrothrombocytopenia without α-granule deficiency or bleeding symptoms. A GFI1B splice variant, c.2520 + 1_2520 + 8delGTGGGCAC, which generates a short GFI1B isoform that lacks non-DNA-binding zinc-fingers 1 and 2, is associated with increased platelet CD34 expression only, without quantitative or morphologic platelet abnormalities. GFI1B represses the CD34 promoter, and this repression is attenuated by different GFI1B zinc-finger mutations, suggesting that deregulation of CD34 expression occurs at a direct transcriptional level. Patient-specific iPSC-derived megakaryocytes phenocopy these observations. Conclusions Disruption of GFI1B non-DNA-binding zinc-finger 1 is associated with mild to moderate thrombocytopenia without α-granule deficiency or bleeding symptomatology, indicating that the site of GFI1B mutation has important phenotypic implications. Platelet CD34 expression appears to be a common feature of perturbed GFI1B function, and may have diagnostic utility.

GFI1B mutation causes a bleeding disorder with abnormal platelet function

BACKGROUND

GFI1B is a transcription factor important for erythropoiesis and megakaryocyte development but previously unknown to be associated with human disease.

METHODS

A family with a novel bleeding disorder was identified and characterized. Genetic linkage analysis and massively parallel sequencing were used to localize the mutation causing the disease phenotype on chromosome 9. Functional studies were then performed in megakaryocytic cell lines to determine the biological effects of the mutant transcript.

RESULTS

We have identified a family with an autosomal dominant bleeding disorder associated with macrothrombocytopenia, red cell anisopoikilocytosis, and platelet dysfunction. The severity of bleeding is variable with some affected individuals experiencing spontaneous bleeding while other family members exhibit only abnormal bleeding with surgery. A single nucleotide insertion was identified in GFI1B that predicts a frameshift mutation in the fifth zinc finger DNA-binding domain. This mutation alters the transcriptional activity of the protein, resulting in a reduction in platelet α-granule content and aberrant expression of key platelet proteins.

CONCLUSIONS

GFI1B mutation represents a novel human bleeding disorder, and the described phenotype identifies GFI1B as a critical regulator of platelet shape, number, and function.

To B or not to B cells-mediate a healthy start to life

Maternal immune responses during pregnancy are critical in programming the future health of a newborn. The maternal immune system is required to accommodate fetal immune tolerance as well as to provide a protective defence against infections for the immunocompromised mother and her baby during gestation and lactation. Natural immunity and antibody production by maternal B cells play a significant role in providing such immunoprotection. However, aberrations in the B cell compartment as a consequence of maternal autoimmunity can pose serious risks to both the mother and her baby. Despite their potential implication in shaping pregnancy outcomes, the role of B cells in human pregnancy has been poorly studied. This review focuses on the role of B cells and the implications of B cell depletion therapy in pregnancy. It highlights the evidence of an association between aberrant B cell compartment and obstetric conditions. It also alludes to the potential mechanisms that amplify these B cell aberrances and thereby contribute to exacerbation of some maternal autoimmune conditions and poor neonatal outcomes. Clinical and experimental evidence suggests strongly that maternal autoantibodies contribute directly to the pathologies of obstetric and neonatal conditions that have significant implications for the lifelong health of a newborn. The evidence for clinical benefit and safety of B cell depletion therapies in pregnancy is reviewed, and an argument is mounted for further clinical evaluation of B cell-targeted therapies in high-risk pregnancy, with an emphasis on improving neonatal outcomes and prevention of neonatal conditions such as congenital heart block and fetal/neonatal alloimmune thrombocytopenia.

The association of depression with platelet activation: evidence for a treatment effect

BACKGROUND

Depression is associated with an increased risk of cardiovascular disease (CVD). Although the mechanism is uncertain, prothrombotic and inflammatory factors may play a role.

OBJECTIVES

As platelets play a key role in CVD, we determined first, whether depressed individuals had more activated platelets than non-depressed individuals and second, whether treatment of depression reduced platelet activation levels.

PATIENTS/METHODS

We recruited 108 depressed outpatients and 45 control subjects all without a history of CVD. After psychological assessment, the depressed patients were offered treatment with medication and/or psychotherapy. Flow cytometric markers of platelet activation and level of depression were assessed at baseline and at 4 weeks and 6 months after treatment.

RESULTS

Depression was associated with increased platelet activation with a higher number of circulating CD62p (0.76x10(9) L(-1) vs. 0.46, P=0.019) and CD63 (P=0.05) positive platelets compared with controls. Patients with depression also had more circulating platelet-leukocyte aggregates than controls (P<0.001). There was a positive correlation between the severity of depression and the level of platelet activation. Platelets from depressed patients were also hyperreactive to adenosine 5 -diphosphate (ADP) stimulation with increased CD62p and CD63 exposure (P=0.003 and 0.019, respectively). Six months of treatment resulted in a reduced number of circulating CD62p and CD63 positive platelets (29.84% and 53.38% decrease) and a 20.9% reduction in CD63 exposure after ADP activation.

CONCLUSIONS

Depression is associated with increased in vivo platelet activation and resolution of depression using psychotherapy and/or medication reduces platelet activation. These findings provide insights into the link between depression and cardiovascular risk.

Use of a functional assay to diagnose protein S deficiency; inappropriate testing yields equivocal results

Inherited deficiency of protein S (PS) is a rare but accepted risk factor for venous thromboembolism. There is accumulating evidence that inherited PS deficiency may be associated with a variety of adverse obstetric events. Acquired PS deficiency may be caused by a variety of clinical states including normal pregnancy. We conducted a retrospective audit of the results of screening for PS deficiency through our reference laboratory. The majority of patients in this audit with significantly reduced (<50%) free functional PS levels had a major confounding factor likely to cause acquired PS deficiency, most frequently pregnancy. Recommendations for PS testing for the diagnosis of hereditary PS deficiency include deferring testing until at least 40 days post-partum. It appears that these recommendations are not being adhered to leading to difficulty in the interpretation of results.

Reduced fibrinolysis and increased fibrin generation can be detected in hypercoagulable patients using the overall hemostatic potential assay

BACKGROUND

Routinely available coagulation assays are not capable of detecting clinically defined hypercoagulable states. A number of global coagulation assays have been developed with the potential to evaluate hypercoagulability, which predisposes to the common clinical events of arterial and venous thromboembolism (VTE).

OBJECTIVES

We hypothesized that the overall hemostatic potential (OHP) assay would show abnormal fibrin generation and lysis in patients with clinically defined hypercoagulable states.

METHODS

We used the OHP assay as described by Blombäck and colleagues [1,2] in 161 clinically hypercoagulable patients with arterial or VTE, pregnancy complications or autoimmune disease. Eighty patients had associated antiphospholipid antibodies (APLA). Ninety-eight normal plasma donors were tested for comparison.

RESULTS

We derived three new assay parameters for correlation with hypercoagulable states: the maximum optical density, maximum slope, and delay in onset of fibrin generation. We found significantly different assay results for all patients' parameters examined when compared with controls, indicating both increased fibrin generation and reduced fibrinolysis in hypercoagulable patients. The findings were similar whether samples were collected in association with an acute thrombotic event or not. Estimated assay sensitivity for detection of a clinically defined hypercoagulable state was 96%.

CONCLUSIONS

The OHP assay is a simple, inexpensive global test that is useful for assessing patients with hypercoagulable states including APLA. OHP results are significantly abnormal in hypercoagulable groups compared with controls, indicating that both increased fibrin generation and reduced fibrinolysis contribute to hypercoagulable states. The assay may ultimately assist in tailoring clinical management to patients' individual requirements.

Genetics of sex pheromone blend differences between Heliothis virescens and Heliothis subflexa: a chromosome mapping approach

Males of the noctuid moths, Heliothis virescens and H. subflexa locate mates based on species-specific responses to female-emitted pheromones that are composed of distinct blends of volatile compounds. We conducted genetic crosses between these two species and used AFLP marker-based mapping of backcross families (H. subflexa direction) to determine which of the 30 autosomes in these moths contained quantitative trait loci (QTL) controlling the proportion of specific chemical components in the pheromone blends. Presence/absence of single H. virescens chromosomes accounted for 7-34% of the phenotypic variation among backcross females in seven pheromone components. For a set of three similar 16-carbon acetates, two H. virescens chromosomes interacted in determining their relative amounts within the pheromone gland and together accounted for 53% of the phenotypic variance. Our results are discussed relative to theories about population genetic processes and biochemical mechanisms involved in the evolution of new sexual communication systems.

The laboratory diagnosis of lupus anticoagulant in patients on oral anticoagulation

Laboratory-specific cut-off lupus ratios (LR), above which a plasma is judged positive for lupus anticoagulant (LA), were established for both activated partial thromboplastin time-based and dilute Russell viper venom time-based methods. The validity of using these cut-off values to determine the presence of LA in patients on oral anticoagulation (OAC) was assessed. A cohort of 40 patients (23 male and 17 female), aged 22-84 years (mean 52 years) were tested for LA at the time of a thrombotic event. Repeated testing was performed after the same patients were treated with OAC (international normalized ratio 2.0-3.5). For 36 patients (90%), LA status was unchanged pre- and on-OAC. Thirteen of the 40 patients (32.5%) were positive for LA both pre- and on-OAC. Of the 27 patients negative for LA pre-OAC, 23 remained negative on-OAC. The four discordant results were interesting in that LA positivity was demonstrated only after the patient was stable on-OAC. In our cohort of 40 patients, there was a trend for LRs to decrease on-OAC, but this did not reach statistical significance. The subset (4) went against this trend and became positive after the thrombotic event.

Aspirin Resistance in Cardiovascular Disease: A Review

BACKGROUND

Aspirin is effective at reducing the cardiovascular event rate in defined patient groups. The introduction of antiplatelet therapies other than aspirin and the concept of aspirin resistance have led to critical reappraisal of current treatment. This review aims to clarify the evidence for aspirin resistance in patients with atherosclerosis.

METHODS

Medline search was performed to identify publications concerned with antiplatelet effects of aspirin and failure of aspirin therapy. Manual cross referencing was also performed.

RESULTS AND CONCLUSION

Wide variations in the rate of aspirin resistance (5.5-75%) have been reported. The lack of consensus on an appropriate definition and the number of different tests used to investigate aspirin resistance needs to be addressed. There are few studies where the primary aim was to document aspirin resistance or aspirin non-response. Further work should aim to investigate if aspirin resistance is clinically important and, if it is, what treatments may be beneficial to the at risk patient.

Identification of aspartic acid 514 through glutamic acid 542 as a glycoprotein Ib-IX complex receptor recognition sequence in von Willebrand factor. Mechanism of modulation of von Willebrand factor by ristocetin and botrocetin

As the first step in hemostasis, the binding of von Willebrand factor (vWF) to the platelet membrane glycoprotein (GP) Ib-IX complex is essential for platelet adhesion at high-shear blood flow. This interaction in vivo requires the prior binding of vWF to the subendothelial matrix, a process which exposes a normally cryptic binding site on vWF for the GP Ib-IX complex. This process can be mimicked in vitro by modulators such as ristocetin or the snake venom protein botrocetin or by desialation of vWF. We have previously localized the GP Ib binding site on vWF to a monomeric dispase fragment which extends from Leu-480/Val-481 to Gly-718 in the primary sequence of mature vWF [Andrews, R. K., Gorman, J. J., Booth, W. J., Corino, G. L., Castaldi, P. A., & Berndt, M. C. (1989) Biochemistry 28, 8326-8336]. This fragment also contains a distinct binding site for botrocetin. Analysis of synthetic peptides corresponding to hydrophilic stretches of sequence within this fragment indicated that the sequence Asp-514-Glu-542 represents a major adhesive sequence involved in receptor recognition. This peptide inhibited both the ristocetin- and botrocetin-mediated binding of vWF to either platelets or purified GP Ib-IX complex (IC50 approximately 50-200 microM) as well as the asialo-vWF- and bovine vWF-dependent agglutination of platelets. Both the N- and C-terminal halves of the peptide were inhibitory but less so than the intact peptide. This peptide also inhibited botrocetin binding to vWF, suggesting that botrocetin modulates vWF-GP Ib interaction by binding in close proximity to the vWF adhesion sequence.(ABSTRACT TRUNCATED AT 250 WORDS)

Conjugation of folate via gelonin carbohydrate residues retains ribosomal-inactivating properties of the toxin and permits targeting to folate receptor positive cells

Conjugation of folate to proteins permits receptor-mediated endocytosis via the folate receptor (FR) and delivery of the conjugate into the cytoplasm of cells. Since many cancers up-regulate the FR it has enabled the targeting of toxins to tumor cells resulting in specific cell death. However, current conjugation methods rely on chemistries that can affect certain catalytic subunits, such as the A-chain of the plant toxin gelonin. As a result many folate-targeted toxins are a compromise between receptor/ligand interaction and toxin activity. We describe the first example of folate conjugated to a protein via carbohydrate residues, using a novel SH-folate intermediate. The folate-gelonin conjugate retains over 99% of toxin activity in a cell-free translational assay compared with unmodified gelonin and is able to bind the FR at the same affinity as free folic acid (10(-10) m). Additionally, the conjugate exhibits prolonged inhibition of protein synthesis in FR positive cell lines in vitro. Folate linked to gelonin via amino conjugation exhibits the same affinity for FR as free folic acid but the toxin is 225-fold less active in a cell-free translational assay. The effect of different conjugation methods on toxin activity and the implications for folate targeting of other glycoproteins are discussed.

Systemic circulation of poly(L-lysine)/DNA vectors is influenced by polycation molecular weight and type of DNA: differential circulation in mice and rats and the implications for human gene therapy

Effective gene therapy for diseases of the circulation requires vectors capable of systemic delivery. The molecular weight of poly(L-lysine) (pLL) has a significant effect on the circulation of pLL/DNA complexes in mice, with pLL(211)/DNA complexes displaying up to 20 times greater levels in the blood after 30 minutes compared with pLL(20)/DNA. It is shown that pLL(20)/DNA complexes fix mouse complement C3 in vitro, independent of immunoglobulin binding; are less soluble in the blood in vivo; bind erythrocytes; are rapidly removed by the liver, where they associate predominantly with Kupffer cells; and result in a rapid increase in hepatic leukocytes expressing high levels of complement receptor 3 (CR3). The circulation properties of these complexes are also dependent on the type of DNA used, with circular plasmid DNA complexes exhibiting increased circulation compared with linear DNA. PLL(211)/DNA complexes bind erythrocytes and associate with Kupffer cells but, in contrast, do not fix mouse complement in vitro and are unaffected by the type of DNA used. In rats, both types of complexes produce hematuria and are rapidly removed from the circulation. Correlation of in vivo and in vitro results suggests that the solubility of complexes in physiological saline and species-matched complement fixation and erythrocyte lysis may correlate with systemic circulation. Analysis using human blood in vitro shows no hemolysis, but both types of complexes fix complement and bind IgG, suggesting that pLL/DNA complexes may be rapidly cleared from the human circulation.

Biophysical characteristics of anti-Gal(alpha)1-3Gal IgM binding to cell surfaces: implications for xenotransplantation

BACKGROUND

Natural antibodies directed against cell surface carbohydrates are thought to be vital to host defense and to initiate the rejection of xenografts and ABO-incompatible allografts. The biophysical properties underlying the association and dissociation of these antibodies from cell surfaces is incompletely understood. We investigated those properties for the binding of Galalpha1-3Gal antibodies to porcine endothelial cell surfaces, because such interactions might be relevant to the clinical application of xenotransplantation.

RESULTS AND CONCLUSIONS

The initial rate of binding of anti-Galalpha1-3Gal antibodies to endothelial cells was found to depend on antibody concentration, antibody diffusion, and antigen concentration. The presence of an intact glycocalyx had a greater impact on antibody binding than mobility of antigen in cell membranes. Disruption of glycocalyx increased the amount of antibody bound at equilibrium by more than 50%. Although the binding of anti-Galalpha1-3Gal antibodies to cell surfaces could be inhibited by soluble Galalpha1-3Gal, once bound, some anti-Galalpha1-3Gal could not be dissociated by competitive inhibitors of binding or by denaturation of the bound Ig with chaotropic reagents, but could be dissociated by reduction of disulfide bonds, suggesting that attachment to cell surfaces was, at least in part, by means other than specific reaction with the epitope.

Folic acid targeting of protein conjugates into ascites tumour cells from ovarian cancer patients

Despite a wealth of in vitro data describing the use of folic acid for drug and DNA delivery into ovarian cancer cell lines, there have been no reports describing the targeting of such compounds to freshly isolated tumour cells. We have carried out a study to determine the usefulness of folic acid as a targeting ligand for ovarian cancer by measuring the uptake of folic acid-BSA-FITC in tumour cells isolated from the ascitic fluid of ovarian cancer patients. In 7 out of 7 patients we have found folic acid mediated uptake of the fluorescently labelled albumin, with the accumulation (average cell fluorescence) and differential uptake (ratio between receptor mediated and fluid phase uptake) varying between patients. Accumulation of folic acid-albumin FITC occurs in ascites tumour cells expressing the epithelial cell marker EMA, with a significant proportion of EMA negative cells also accumulating the conjugate. There is no correlation between cell cycle and uptake of folic acid-BSA-FITC. These results suggest that folic acid-targeting of therapeutics is a promising approach for the treatment of ovarian cancer.

A versatile system for receptor-mediated gene delivery permits increased entry of DNA into target cells, enhanced delivery to the nucleus and elevated rates of transgene expression

We have developed a method for stabilisation of polyelectrolyte gene delivery vectors by crosslinking their surfaces with biodegradable multivalent copolymers based on N-(2-hydroxypropyl)methacrylamide (HPMA). The resulting nanoparticulate vectors resist attack by serum proteins and can be modified for cell-specific delivery by incorporation of targeting ligands onto the polymer coating. Here we show that vascular endothelial growth factor (VEGF), transferrin and basic fibroblast growth factor (bFGF) can each be linked to polyHPMA-coated poly(L-lysine)/DNA complexes. All ligand-targeted complexes demonstrated increased uptake into receptor-positive cells (measured using plasmids containing 32P-dCTP), that could be antagonised with excess free ligand. Targeted complexes also showed increased transfection, resistant to inhibition by serum, suggesting the possibility of effective application in vivo. Analysis using fluorescence microscopy confirmed enhanced uptake of ligand-targeted complexes (using Texas Red-labelled plasmid DNA), although VEGF- and transferrin-targeted complexes were restricted to cytoplasmic or perinuclear distributions. In contrast, bFGF-targeted complexes showed efficient delivery into the nucleus, with accumulation of more than 100000 plasmids per cell within distinct intranuclear compartments. This method permits versatile targeting of genes to selected cells and may also permit manipulation of intracellular trafficking. It should find several important applications in gene delivery systems both in vitro and in vivo.

A Leu262Pro mutation in the integrin beta(3) subunit results in an alpha(IIb)-beta(3) complex that binds fibrin but not fibrinogen

Platelet retraction of a fibrin clot is mediated by the platelet fibrinogen receptor, alpha(IIb)beta(3). In certain forms of the inherited platelet disorder, Glanzmann thrombasthenia (GT), mutant alpha(IIb)beta(3) may interact normally with fibrin yet fail to support fibrinogen-dependent aggregation. We describe a patient (LD) with such a form of GT. Platelets from LD supported normal clot retraction but failed to bind fibrinogen. Platelet analysis using flow cytometry and immunoblotting showed reduced but clearly detectable alpha(IIb)beta(3), findings consistent with type II GT. Genotyping of LD revealed 2 novel beta(3) mutations: a deletion of nucleotides 867 to 868, resulting in a premature stop codon at amino acid residue 267, and a T883C missense mutation, resulting in a leucine (Leu) 262-to-proline (Pro) substitution. Leu262 is highly conserved among beta integrin subunits and lies within an intrachain loop implicated in subunit association. Leu262Probeta(3) cotransfected with wild-type alpha(IIb) into COS-7 cells showed delayed intracellular maturation and reduced surface expression of easily dissociable complexes. In human embryonic kidney 293 cells, Leu262Probeta(3) formed a complex with endogenous a(v) and retracted fibrin clots similarly to wild-type beta(3). The same cells, however, were unable to bind immobilized fibrinogen. The molecular requirements for alpha(IIb)beta(3) to interact with fibrin compared with fibrinogen, therefore, appear to differ. The region surrounding beta(3) Leu262 may maintain beta(3) in a fibrinogen-binding, competent form, but it appears not to be required for receptor interactions with fibrin.

Folate-targeted non-viral DNA vectors for cancer gene therapy

The vitamin folic acid exhibits high affinity for the endocytosed, membrane-bound folate receptor. Conjugation of folic acid via its gamma-carboxyl group to various macromolecules results in binding to, and endocytosis into, cells expressing the folate receptor. The folate receptor is overexpressed on a wide range of cancers, therefore folic acid has been investigated as a targeting ligand for the specific delivery of therapeutic compounds to cancer cells. This review will introduce folate-targeting of macromolecules to cancer cells in vitro and in vivo, and discuss the accumulation of such compounds in non-target tissues in vivo. Folate-targeting of non-viral DNA vectors in vitro and in vivo will be discussed in detail, with particular emphasis on the recent advances in this field.

Reducing intergroup bias: elements of intergroup cooperation

The authors examined the potentially separable contributions of 2 elements of intergroup cooperation, interaction and common fate, and the processes through which they can operate. The manipulation of interaction reduced bias in evaluative ratings, which supports the idea that these components are separable, whereas the manipulation of common fate when the groups were interacting was associated with lower bias in nonverbal facial reactions in response to contributions by in-group and out-group members. Whereas interaction activated several processes that can lead to reduced bias, including decategorization, consistent with the common in-group identity model (S. L. Gaertner, J. F. Dovidio, P. A. Anastasio, B. A. Bachman, & M. C. Rust, 1993) as well as M. Hewstone and R. J. Brown's (1986) group differentiation model, the primary set of mediators involved participants' representations of the memberships as 2 subgroups within a superordinate entity.

Monoclonal anti-idiotype antibody mimicking the pesticide binding site of cutinase: potential for broad specificity organophosphate recognition

An anti-idiotype monoclonal antibody (Mab) able to bind the organophosphate pesticides, chlorfenvinphos (CFV), ethyl paraoxon, tetrachlorfenvinphos and demeton-s-methyl, has been produced using as immunogen a Mab which binds to the active site of cutinase. The principle of using an anti-idiotype antibody as the mimic of a site on a protein able to bind a group of ligands has, therefore, been demonstrated, and may have implications for future research on broad specificity immunoanalysis of groups of compounds.

Reducing intergroup bias: elements of intergroup cooperation

The authors examined the potentially separable contributions of 2 elements of intergroup cooperation, interaction and common fate, and the processes through which they can operate. The manipulation of interaction reduced bias in evaluative ratings, which supports the idea that these components are separable, whereas the manipulation of common fate when the groups were interacting was associated with lower bias in nonverbal facial reactions in response to contributions by in-group and out-group members. Whereas interaction activated several processes that can lead to reduced bias, including decategorization, consistent with the common in-group identity model (S. L. Gaertner, J. F. Dovidio, P. A. Anastasio, B. A. Bachman, & M. C. Rust, 1993) as well as M. Hewstone and R. J. Brown's (1986) group differentiation model, the primary set of mediators involved participants' representations of the memberships as 2 subgroups within a superordinate entity.

Unstable expansion of the CAG trinucleotide repeat in MAB21L1: report of a second pedigree and effect on protein expression

MAB21L1, originally termed CAGR1, is the human homologue of the C. elegans cell fate determining gene mab21. MAB21L1, mapped to 13q13, contains a highly polymorphic 5' untranslated CAG repeat that normally ranges from six to 31 triplets in length. A pedigree has been previously reported in which the repeat length is expanded to 45-50 triplets and is transmitted unstably between generations; the expansion did not correlate to a clinical phenotype but did exhibit somatic mosaicism. We now report a second pedigree with an expanded and unstably transmitted MAB21L1 CAG repeat of similar length. The expansion is not clearly associated with a clinical phenotype, though the complexity of the pedigree renders any conclusion concerning phenotype-genotype relationships speculative. The expansion did not result in decreased expression of MAB21L1 protein. The length, C-G rich composition, somatic mosaicism, and unstable transmission of the expanded CAG repeat in MAB21L1 resemble the premutations observed in other genes, such as FMR1 and MDPK, in which longer expanded repeats are associated with a clinical phenotype. This raises the possibility that longer expansions in the MAB21L1 repeat may also be associated with a clinical phenotype.

A frameshift mutation at Gly975 in the transmembrane domain of GPIIb prevents GPIIb-IIIa expression--analysis of two novel mutations in a kindred with type I glanzmann thrombasthenia

Two Hispanic siblings presenting with lifelong mucocutaneous bleeding were diagnosed clinically with Glanzmann thrombasthenia on the basis of a normal platelet count, prolonged bleeding time and absent platelet aggregation in response to multiple agonists. Quantitative analysis of the probands' platelets by flow cytometry showed a complete absence of GPIIb-IIIa, consistent with Type I thrombasthenia. Genetic analysis showed the probands to be compound heterozygotes for two novel mutations of GPIIb: a C1414>G mutation in exon 14, resulting in a premature termination codon replacing residue Tyr440, and the insertion of a G at position 3016 in exon 29, leading to a frameshift affecting the C-terminal half of the transmembrane domain and the cytoplasmic tail. The frameshifted sequence alters residues from Gly975 onwards and is predicted to significantly alter the hydropathy and charge profiles of the GPIIb transmembrane domain. The Type I phenotype associated with this mutation suggests that GPIIb residues 975-1008 contain critical structural motifs for heterodimer assembly, membrane retention, export from the ER and surface expression.

Binding of the von Willebrand factor A1 domain to histone

Activation of the von Willebrand Factor (vWF) A1 domain is a critical factor in regulating the interaction of vWF with its platelet membrane receptor, the glycoprotein (GP) Ib-IX-V complex. This activation controls vWF-dependent platelet adhesion at high shear. The vWF-GP Ib-IX-V interaction is induced in vivo by exposure of platelet-rich plasma to high shear force, or by association of vWF with one or more unidentified components of the subendothelial matrix. In vitro, soluble vWF is activated to bind to platelets by nonphysiological modulators, such as the bacterial glycopeptide, ristocetin, or the snake venom protein, botrocetin, or by removal of negatively-charged sialic acid residues. Analysis of vWF modulators and the very marked charge asymmetry of amino acid sequences within the A1 domain has led to an electrostatic model for vWF modulation. Endothelial membrane/matrix and detergent-soluble fractions of human placenta were screened for the ability to bind vWF by electrophoresis of extracts on SDS-polyacrylamide gels, electrotransferring to nitrocellulose and probing with fluid-phase 125I-labeled vWF or a 39/34-kDa vWF fragment (Leu-480-Gly-718) that encompasses the A1 domain. In the course of these studies, it was found that both vWF and the 39/34-kDa vWF fragment bound strongly to histone. Purified soluble histone also bound vWF since, like ristocetin, it induced vWF flocculation. Histone binding to vWF did not activate or inhibit vWF binding to platelets. While the vWF-histone interaction has no conceivable physiological role, it suggests that binding to the A1 domain of vWF alone is insufficient to modulate vWF adhesive activity. This implies that specific interactions of the vWF A1 domain with either ristocetin or botrocetin are required for GP Ib-IX-V recognition to occur.

The protein-tyrosine phosphatase SHP-2 binds platelet/endothelial cell adhesion molecule-1 (PECAM-1) and forms a distinct signaling complex during platelet aggregation. Evidence for a mechanistic link between PECAM-1- and integrin-mediated cellular signaling

Platelet/endothelial cell adhesion molecule-1 (PECAM-1) is a homophilic adhesion receptor that mediates leukocyte/endothelial cell interactions that take place during transendothelial migration. Recent reports have shown that the binding of certain anti-PECAM-1 antibodies results in up-regulation of integrin function on the surface of leukocytes and platelets, suggesting that PECAM-1 may be capable of transmitting information into the cell following its engagement. PECAM-1 isolated from resting or activated but nonaggregated platelets was phosphorylated predominantly on serine residues; however, PECAM-1 derived from activated, aggregated platelets was strongly phosphorylated on tyrosine. Synthetic tyrosine-phosphorylated peptides derived from five different regions within the cytoplasmic domain of PECAM-1 were screened for their ability to associate with cytoplasmic signaling molecules. The protein-tyrosine phosphatase SHP-2 was found to interact specifically with two different PECAM-1 phosphopeptides containing highly conserved phosphatase-binding motifs on PECAM-1 with the sequences VQpY663TEV and TVpY686SEV. More important, SHP-2 bound not only PECAM-1 phosphopeptides, but also became associated with full-length cellular PECAM-1 during the platelet aggregation process, and this interaction was mediated by the amino-terminal Src homology 2 domains of the phosphatase. Since SHP-2 normally serves as a positive regulator of signal transduction, its association with activated PECAM-1 suggests a number of potential mechanisms by which PECAM-1 engagement might be coupled to integrin activation in vascular cells.

Characterization of mocarhagin, a cobra venom metalloproteinase from Naja mocambique mocambique, and related proteins from other Elapidae venoms

Mocarhagin, a cobra venom metalloproteinase from Naja mocambique mocambique, has previously been shown to cleave selectively two mucin-like substrates on platelets and neutrophils within anionic amino acid sequences containing sulfated tyrosines. We now show that purified mocarhagin has haemagglutinin activity, and a similar profile for inhibition of mocarhagin-dependent haemagglutination and proteolysis suggests that the lectin-like domain may account for its substrate specificity. In addition, immunologically and functionally related proteins were detected in other Elapidae venoms.

Binding of a novel 50-kilodalton alboaggregin from Trimeresurus albolabris and related viper venom proteins to the platelet membrane glycoprotein Ib-IX-V complex. Effect on platelet aggregation and glycoprotein Ib-mediated platelet activation

Binding of the multimeric adhesive glycoprotein, von Willebrand Factor (vWF), to the platelet membrane glycoprotein (GP) Ib-IX-V complex mediates platelet adhesion and initiates signal transduction leading to platelet activation. Recently described viper venom proteins that bind to the GP Ib alpha-chain and inhibit vWF binding provide novel probes for studying receptor function. We have purified a 50-kDa form of alboaggregin from the white-lipped tree viper (Trimeresurus albolabris) and two 25-kDa proteins, CHH-A and CHH-B, from the timber rattlesnake (Crotalus horridus horridus) in addition to a previously described 25-kDa alboaggregin and echicetin. Complete or partial amino acid sequencing of CHH-A, CHH-B, and 50-kDa alboaggregin and cross-reactivity of these proteins with an anti-botrocetin antiserum confirmed that they were disulfide-linked heterodimers or higher multimers of the C-type lectin protein family. These proteins, together with 25-kDa alboaggregin and echicetin, specifically bound to GP Ib alpha within the N-terminal peptide domain, His-1-Glu-282, and inhibited vWF binding with comparable IC50 values (approximately 0.2 microgram/mL). However, cross-blocking studies between these structurally related proteins and anti-GP Ib alpha monoclonal antibodies demonstrated that the venom protein binding sites were not congruent. Further, the 50-kDa alboaggregin, but not the other venom proteins, potently induced platelet activation as assessed by dense granule serotonin release or elevation of cytosolic ionized calcium. Treatment of platelets with the 50-kDa alboaggregin was associated with activation of protein kinase C and tyrosine kinase(s), resulting in a platelet protein phosphorylation profile similar to that seen on shear-stress-induced vWF binding to platelets. These results suggest that the 50-kDa alboaggregin induces cytoplasmic signaling coincident with its binding to the GP Ib-IX-V complex and provides a potentially useful probe for studying the mechanism of vWF-dependent platelet activation.

The separation and determination of quinine in bitter drinks by micellar electrokinetic capillary chromatography

A rapid method for the determination of quinine in bitter drinks by micellar electrokinetic capillary chromatography (MECC) with ultraviolet (UV) detection is described. The beverage is simply diluted with deionized water, filtered, and analyzed using a 75 cm x 75 micrometer uncoated fused-silica capillary column with a buffer consisting of 15% methanol and 85% of a mixture of 0.05 M cetyltrimethylammonium bromide (CTAB), 0.01 M sodium tetraborate, and 0.01 M potassium dihydrogen orthophosphate, pH 8.6, with an operating voltage of -25 kV. The levels of quinine determined by MECC were in good agreement with those determined by HPLC. The CVs for area calculation (2.1%, n = 7) and migration time variation (1.3%, n = 20) for multiple injections of a sample solution by MECC were satisfactory.

Mocarhagin, a novel cobra venom metalloproteinase, cleaves the platelet von Willebrand factor receptor glycoprotein Ibalpha. Identification of the sulfated tyrosine/anionic sequence Tyr-276-Glu-282 of glycoprotein Ibalpha as a binding site for von Willebrand factor and alpha-thrombin

Platelet adhesion to the subendothelium is the initiating event in hemostasis and thrombosis and involves the binding of von Willebrand factor (vWF) by the platelet membrane glycoprotein (GP) Ib-IX complex. The alpha-chain of GP Ib contains binding sites for both vWF and alpha-thrombin within a 45-kDa N-terminal tryptic fragment. In the present study, we have further delineated these sites using smaller proteolytic fragments and functional antibodies. Mocarhagin, a cobra venom metallaproteinase, generates the fragment His-1-Glu-282, while cathepsin G, a neutrophil granule serine protease, generates a slightly smaller fragment, His-1-Leu-275. His-1-Glu-282 was as effective as intact soluble GP Ibalpha (glycocalicin) in inhibiting botrocetin-dependent binding of vWF to washed platelets (IC50 approximately 0.3 microM) whereas His-1-Leu-275 was an order of magnitude less effective (IC50 approximately 3 microM). Residues Tyr-276-Glu-282 (YDYYPEE) are part of an anionic region homologous to thrombin-binding molecules such as hirudin. In ligand blot analysis, thrombin blotted the His-1-Glu-282 fragment, but not His-1-Leu-275. The three tyrosine residues within Tyr-276-Glu-282 meet the consensus criteria for O-sulfation. A method was developed to distinguish O-sulfated from nonsulfated tyrosine residues based on differences in the UV absorbance spectra. Residues Tyr-276-Glu-282 were isolated from glycocalicin by proteolysis with mocarhagin and cathepsin G. Ion spray mass spectrometry confirmed that Tyr-278 and Tyr-279 was only approximately 50% O-sulfated. Four anti-GP Ibalpha monoclonal antibodies (SZ2, ES85, C34 and VM16d) were found to be modulator-specific, strongly inhibiting botrocetin-dependent binding of vWF, but having less or no effect on ristocetin-dependent vWF binding. These antibodies also inhibited the binding of thrombin to fixed platelets. Immunoprecipitation with GP ibalpha fragments defined the epitopes for these antibodies as SZ2 (Tyr-276-Glu-282), ES85 (Asp-283-Arg-293), C34 (His-1-Glu-282), and VM16d (His-1-Leu-275). An antibody which inhibited ristocetin-dependent, as well as botrocetin-dependent, vWF binding but had no effect on thrombin binding (Ak2) had an epitope within His-1-Leu-275. These findings indicate that the sulfated tyrosine/anionic GP Ibalpha residues Tyr-276-Glu-282 are important for the binding of thrombin and botrocetin-dependent binding of thrombin and the botrocetin-dependent binding of vWF, but that vWF also interacts with residues within His-1-Leu-275.

The molecular mechanism of platelet adhesion

One of the most primitive of host-defence mechanisms is haemostasis, the ability to control blood loss. In response to vascular trauma, platelets rapidly adhere to the exposed subendothelial matrix, a process that ultimately results in the sealing of the vessel by a plug of platelets stabilised by fibrin. Paradoxically, it is the same cascade of events that leads to thrombosis and vessel occlusion, resulting in heart attack and stroke. The molecular events involved in platelet adhesion have therefore been the subject of intense investigation. In all but the largest blood vessels, the initial contact adhesion of platelets is mediated by subendothelial matrix bound von Willebrand Factor (vWF) and a specific vWF receptor on platelets, the glycoprotein (GP) Ib-V-IX complex. Our understanding of this process arose from analysis of two congenital bleeding disorders, von Willebrand's disease and the Bernard-Soulier syndrome, in which vWF or the GP Ib-V-IX, respectively, are either absent or dysfunctional. This overview discusses our current molecular understanding of platelet adhesion and how engagement of vWF by the GP Ib-V-IX complex on platelets initiates the subsequent events in platelet activation leading to either haemostasis or thrombosis.

Jararhagin and jaracetin: novel snake venom inhibitors of the integrin collagen receptor, alpha 2 beta 1

Two novel proteins, jararhagin and jaracetin, were purified from Bothrops jararaca viper venom. Jararhagin is a 55-kDa member of the metalloprotease-disintegrin family. Jaracetin is a 60-kDa dimer representing a differently processed form of jararhagin. Like botrocetin, a previously described viper venom protein, jararhagin and jaracetin modulated binding of von Willebrand Factor to the glycoprotein Ib-IX complex on platelets through a specific interaction with the von Willebrand Factor A1 domain. Both jararhagin and jaracetin, but not botrocetin, also blocked alpha 2 beta 1-dependent platelet adhesion to collagen, a receptor interaction mediated through a homologous A domain on the integrin alpha 2 subunit.