Lessons from the Ebola Outbreak: Action Items for Emerging Infectious Disease Preparedness and Response

EcoHealth - As the Ebola outbreak in West Africa wanes, it is time for the international scientific community to reflect on how to improve the detection of and coordinated response to future...     

Structural evidence for the order of preference of inorganic substrates in mammalian heme peroxidases: crystal structure of the complex of lactoperoxidase with four inorganic substrates,SCN-, I-, Br– and Cl-

Lactoperoxidase (LPO) is a member of the family of mammalian heme peroxidases. It catalyzes the oxidation of halides and pseudohalides in presence of hydrogen peroxide. LPO has been co-crystallized with inorganic substrates, SCN^-, I^-, Br^- and Cl^-. The structure determination of the complex of LPO with above four substrates showed that all of them occupied distinct positions in the substrate binding site on the distal heme side. The bound substrate ions were separated from each other by one or more water molecules. The heme iron is coordinated to His-351 N^ϵ2 on the proximal side while it is coordinated to conserved water molecule W-1 on the distal heme side. W-1 is hydrogen bonded to Br^- ion which is followed by Cl^- ion with a hydrogen bonded water molecule W-5′ between them. Next to Cl^- ion is a hydrogen bonded water molecule W-7′ which in turn is hydrogen bonded to W-8′ and N atom of SCN^-. W-80 is hydrogen bonded to W-9′ which is hydrogen bonded to I^-. SCN^- ion also interacts directly with Asn-230 and through water molecules with Ser-235 and Phe-254. Therefore, according to the locations of four substrate anions, the order of preference for binding to lactoperoxidase is observed as Br^- > Cl^- > SCN^- > I^-. The positions of anions are further defined in terms of subsites where Br^- is located in subsite 1, Cl^- in subsite 2, SCN^- in subsite 3 and I^- in subsite 4.     

Priming biotic factors for optimal protocorm-like body and callus induction in hybrid Cymbidium (Orchidaceae), and assessment of cytogenetic stability in regenerated plantlets

Protocorm-like bodies (PLBs) and callus were induced in epiphytic hybrid Cymbidium Twilight Moon ‘Day Light’, where induction capacity was strongly explant dependent. Following the use of various explant sources (PLB, leaf tip or base, root tip or base, cell and tissue ‘suspension’), highest PLB formation and callus induction occurred when we used whole PLBs, PLB segments or PLB transverse thin cell layers (tTCLs) or longitudinal TCLs (lTCLs). Plantlet growth and photosynthetic state from whole or bisected PLBs, as well as from tTCLs were not significantly different, after analysis of chlorophyll content. However plantlets generated from lTCLs showed lower values for growth and photosynthetic parameters. All resultant plants were shown to be cytogenetically identical using RAPD and mtDNA analysis despite cytological variation and endopolyploidy occuring between different plant parts. Acclimatization and survival rate was shown to be 100% in the generated plants.     

Reproductive characterization and preliminary studies on controlled breeding of Annatto (Bixa orellana L.)

Annatto (Bixa orellana L.) is an important dye-yielding medium-sized tree occurring in the tropics. Investigations aimed at elucidating the reproductive characters as well as establishing a set of breeding parameters for genetic improvement of B. orellana was carried out. Records on pollen/ovule ratios of annatto showed that this species is xenogamous. The acetolyzed pollen of B. orellana was tricolporate. The fluorochromatic test showed 95% pollen viability. The viability of the pollen grains decreased sharply after 4 h from anther dehiscence. The optimum time range for artificial pollination was standardized between 12:00 and 13:00 h. A high in vitro germination rate (92%) of freshly collected pollen was recorded in modified Brewbaker’s medium with 15% sucrose. Resource allocation studies showed that the construction of each flower cost 1.162 g. The floral vegetative cost was 75%. Of the total allocation, 21% was spent by the stamens. Based on identified reproductive characters, controlled pollination experiments were conducted by selecting four morphologically distinct parent plants: (1) green-fruited with reddish spines, (2) red-fruited, (3) brown large-fruited, and (4) with brown distorted fruits. In artificial cross-pollination experiments, wide variation ranges in fruit set (0–95%) and fruit maturation (0–85%) were observed in different crosses. The number of seeds per capsule also showed variation (0–40 per capsule). Germination studies of seeds raised from different crosses showed a maximum 93% germination. The present study proved that improvement in B. orellana could be achieved by adopting breeding techniques using specifically selected parents.     

Nuclear disintegration of target cells by killer B lymphocytes from tumor-bearing mice

Normal murine B lymphocytes are not known to be effectors of the Fc receptor-mediated, antibody-dependent cellular cytotoxicity (ADCC). In contrast, we report here that highly purified splenic B cells from mammary tumor-bearing mice develop the potential of lysing antibody-coated target cells. These lymphocytes are characterized by being G-10 nonadherent, nylon wool adherent, sIg+, FcR+, Thy 1.2-, asialo GM1-, and the immunoglobulin heavy-chain genes of both chromosomes are rearranged. The lytic reaction is characterized by a noninterdigitating binding and by the appearance of endocytotic vesicles in the target cells. Nuclear disintegration occurs 18 h after initial effector-target cell conjugate formation. At such time, only minor cytoplasmic membrane alterations are evident. The emergence of killer B cells in tumor-bearing hosts indicates that all lymphoreticular cell types bearing Fc receptors are capable of mediating ADCC.     

The nucleotide sequence of the right-hand terminal SmaI-K fragment of adenovirus type 2 DNA

The primary structure of the SmaI-K fragment of adenovirus type 2 (Ad2) DNA has been determined. This region includes one of the origins of DNA replication (Winnacker, 1978; Sussenbach and Kuijk, 1978). A leader sequence for an early mRNA in region 4 (Berk and Sharp, 1977; 1978) has also been mapped in this region. The comparison of the primary structure of this region in Ad2 DNA with the corresponding region in Ad5 DNA shows a remarkable homology which may be significant in view of the fact that Ad2 and Ad5 DNAs can interchangeably function in the in vitro replication system of Challberg and Kelly (1979).     

Naringenin enhanced efficiency ofRhizobium meliloti-alfalfa symbiosis

Rhizobium meliloti-alfalfa (Medicago sativa) symbiosis was influenced by the rhizospheric application of naringenin which increased nodule number, nodule weight (2-to 8-fold) and nitrogenase activity. Plant blomass and total nitrogen content also increased by 60 to 72%. The enhancing effects of naringenin were more pronounced if it was applied at the early vegetative stage of plant growth or at the time of sowing.