Characterization of a membrane-bound C-glucosyltransferase responsible for carminic acid biosynthesis in Dactylopius coccus Costa

Carminic acid is a widely applied red colorant that is still harvested from insects because its biosynthesis is not fully understood. Here, the authors identify and characterize a membrane-bound C-glucosyltransferase catalyzing the final step during carminic acid biosynthesis

SHINE Transcription Factors Act Redundantly to Pattern the Archetypal Surface of Arabidopsis Flower Organs

Floral organs display tremendous variation in their exterior that is essential for organogenesis and the interaction with the environment. This diversity in surface characteristics is largely dependent on the composition and structure of their coating cuticular layer. To date, mechanisms of flower organ initiation and identity have been studied extensively, while little is known regarding the regulation of flower organs surface formation, cuticle composition, and its developmental significance. Using a synthetic microRNA approach to simultaneously silence the three SHINE (SHN) clade members, we revealed that these transcription factors act redundantly to shape the surface and morphology of Arabidopsis flowers. It appears that SHNs regulate floral organs' epidermal cell elongation and decoration with nanoridges, particularly in petals. Reduced activity of SHN transcription factors results in floral organs' fusion and earlier abscission that is accompanied by a decrease in cutin load and modified cell wall properties. SHN transcription factors possess target genes within four cutin- and suberin-associated protein families including, CYP86A cytochrome P450s, fatty acyl-CoA reductases, GSDL-motif lipases, and BODYGUARD1-like proteins. The results suggest that alongside controlling cuticular lipids metabolism, SHNs act to modify the epidermis cell wall through altering pectin metabolism and structural proteins. We also provide evidence that surface formation in petals and other floral organs during their growth and elongation or in abscission and dehiscence through SHNs is partially mediated by gibberellin and the DELLA signaling cascade. This study therefore demonstrates the need for a defined composition and structure of the cuticle and cell wall in order to form the archetypal features of floral organs surfaces and control their cell-to-cell separation processes. Furthermore, it will promote future investigation into the relation between the regulation of organ surface patterning and the broader control of flower development and biological functions

Host Genetics and HIV-1: The Final Phase?

This is a crucial transition time for human genetics in general, and for HIV host genetics in particular. After years of equivocal results from candidate gene analyses, several genome-wide association studies have been published that looked at plasma viral load or disease progression. Results from other studies that used various large-scale approaches (siRNA screens, transcriptome or proteome analysis, comparative genomics) have also shed new light on retroviral pathogenesis. However, most of the inter-individual variability in response to HIV-1 infection remains to be explained: genome resequencing and systems biology approaches are now required to progress toward a better understanding of the complex interactions between HIV-1 and its human host

Contrasting Roles for TLR Ligands in HIV-1 Pathogenesis

The first line of a host's response to various pathogens is triggered by their engagement of cellular pattern recognition receptors (PRRs). Binding of microbial ligands to these receptors leads to the induction of a variety of cellular factors that alter intracellular and extracellular environment and interfere directly or indirectly with the life cycle of the triggering pathogen. Such changes may also affect any coinfecting microbe. Using ligands to Toll-like receptors (TLRs) 5 and 9, we examined their effect on human immunodeficiency virus (HIV)-1 replication in lymphoid tissue ex vivo. We found marked differences in the outcomes of such treatment. While flagellin (TLR5 agonist) treatment enhanced replication of CC chemokine receptor 5 (CCR 5)-tropic and CXC chemokine receptor 4 (CXCR4)-tropic HIV-1, treatment with oligodeoxynucleotide (ODN) M362 (TLR9 agonist) suppressed both viral variants. The differential effects of these TLR ligands on HIV-1 replication correlated with changes in production of CC chemokines CCL3, CCL4, CCL5, and of CXC chemokines CXCL10, and CXCL12 in the ligand-treated HIV-1-infected tissues. The nature and/or magnitude of these changes were dependent on the ligand as well as on the HIV-1 viral strain. Moreover, the tested ligands differed in their ability to induce cellular activation as evaluated by the expression of the cluster of differentiation markers (CD) 25, CD38, CD39, CD69, CD154, and human leukocyte antigen D related (HLA)-DR as well as of a cell proliferation marker, Ki67, and of CCR5. No significant effect of the ligand treatment was observed on apoptosis and cell death/loss in the treated lymphoid tissue ex vivo. Our results suggest that binding of microbial ligands to TLRs is one of the mechanisms that mediate interactions between coinfected microbes and HIV-1 in human tissues. Thus, the engagement of appropriate TLRs by microbial molecules or their mimetic might become a new strategy for HIV therapy or prevention

Human antibody responses to the Plasmodium vivax Duffy Binding protein in Sri Lanka

Recombinant protein DBP, expressed in a bacculoviral vector, representing the native Plasmodium vivax Duffy Binding Protein (DBP) was used in an indirect ELISA to assay the total anti-DBP antibody (IgM + IgG) responses in Sri Lankan patients with acute vivax malaria. The test populations were selected from two malaria endemic areas, Anuradhapura (n=64) and Kataragama (n=93), and from an area non-endemic for malaria, Colombo (n=91). The prevalences of anti-DBP antibodies were 53%, 38% and 44% from Anuradhapura, Kataragama and Colombo, respectively. A significant difference (Chi-square test, p<0.05) was found between the proportions of responders and non-responders to DBP in Kataragama. Responding proportions of individuals previously exposed (PE) and previously not exposed (PNE) differed significantly only in Colombo (Chi-square test, p<0.05). Significant differences (Mann-Whitney U test, p<0.05) were evident between anti-DBP antibody magnitudes; (i) in Anuradhapura and Kataragama and (ii) of PNE individuals from Colombo and the total responders (both PNE + PE) from Anuradhapura. A significant difference (Mann-Whitney U test, p<0.01) in the end point titers (EPT) between PNE and PE individuals was limited to Colombo. Associations between host factors (age, parasitaemia, number of past infections, the duration between present and penultimate infections and the days of symptoms) and total antibody responses (antibody magnitudes and EPT) were examined (Spearman Correlation coefficient, p<0.05). The significant associations found were between (i) parasitaemia and then total antibody responses of residents in Anuradhapura, (ii) between the parasitaemia group <0.01% and the total antibody response of residents in Kataragama (a negative correlation), (iii) number of past infections in Colombo and (iv) the duration between the present and penultimate infections in Colombo and in Anuradhapura with EPT and the antibody magnitudes, respectively. In conclusion, results of the present study imply that naturally acquired anti-DBP antibodies may play a functional role in the immunity to vivax malaria in Sri Lanka. Acknowledgement: Financial assistance by the University of Colombo and the International foundation for Science, Sweden (Grant No: F3008-1

Comparison of the two different recombinant proteins representing region II of the Duffy binding protein of Plasmodium vivax by assaying for natural antibodies

Two different recombinant proteins representing region II of the Duffy Binding Protein of Plasmodium vivax, DBP and PvRII expressed in the bacculovirus and Eschericia coli vector systems, respectively, were compared by assaying the total immunoglobulin (IgM + IgG) responses of sera of patients with acute vivax malaria in an indirect ELISA. The patients were from two malaria endemic areas, Anuradhapura (n=64) and Kataragama (n=90), and a nonendemic area, Colombo (n=90). The antibody prevalence was 50% and 44% from Anuradhapura, 39% and 28% Kataragama and 57% and 41% from Colombo, for PvRII and DBP, respectively. The antibody prevalence for PvRII was higher than that for DBP in each test area, that was significant only in Colombo (p=0.001). The percentages of patients that they responded to both proteins were 34% (n=22), 19% (n=17) and 40% (n=36) from Anuradhapura, Kataragama and from Colombo, respectively. In comparison, a significantly lower (p=0.007) percentage of individuals from Kataragama responded to both proteins. Further 16% (n=10) from Anuradhapura, 19% (n=17) from Kataragama and 16% (n=14) from Colombo preferentially recognised PvRII, whereas, corresponding values for DBP were 9% (n=6), 10% (n=9) and 1% (n=1), respectively, where this difference was significant only in Colombo (p=0.031). Among the previously non-exposed patients from Colombo, 24% responded preferentially to PvRII whereas it was only 3% for DBP (p=0.021).On the other hand, of the previously exposed patients from Colombo, 10% preferentially responded to PvRII whereas no preferential recognition of DBP was observed (p=0.063). Thus the results of this study show a higher natural antibody response to recombinant protein PvRII, which represents the functional conformation of region II of the Duffy Binding Protein. We are thankful to Dr Chitnis, Malaria Division, ICGEB, New Delhi, India and Dr S Longacre, Department of Immunology, Institute Pasteur, France for kindly providing the two recombinant proteins. Financial support by the International Foundation for Science, Sweden (Grant No: F3008-1) and University of Colombo (Grant No: 2001/S/23) are acknowledged