Evaluation of the Subhuman Primate Pregnancy Test Kit for the detection of early pregnancy in the rhesus monkey (Macaca mulatta)

The performance of The Subhuman Primate Pregnancy Test Kit was evaluated for routine detection of early (days 19-21) pregnancy in the rhesus monkey. Out of 123 confirmed matings, 19 resulted in pregnancy. In the pregnant animals the kit had an accuracy of 73.7%. In the nonpregnant females the accuracy was higher, 88.5%. False positives were encountered in ovariectomized females as well as adult intact males.     

Conformation of human fibrinogen in solution from polarized triplet spectroscopy.

The rotational motions of human fibrinogen in solution at 20 degrees C have been examined, in the 0.2-12-microseconds time range, by measuring the laser-induced dichroism of the triplet state of an erythrosin probe covalently bonded to the protein. The decay of the anisotropy was multiexponential, and up to three correlation times (phi 1 = 380 +/- 50 ns, phi 2 = 1.1 +/- 0.1 microseconds, and phi 3 = 3.3 +/- 0.6 microseconds) were needed to obtain a satisfactory analysis. The experimental data are consistent with the brownian motions of an elongated, rigid particle. If the correlation times are combined with previous data on the intrinsic viscosity of fibrinogen, the rotational and translational diffusive properties of the protein can be reproduced with high accuracy by idealizing it as an elongated ellipsoid of revolution with dimensions (2a x 2b) of (54 +/- 6) x (7.2 +/- 0.5) nm, having rotational diffusion constants of D parallel = (6.2 +/- 0.7) x 10(5) s-1 and D perpendicular = (5 +/- 1) x 10(4) s-1. The possibility of Ca(2+)-dependent changes in the rigidity or conformation of fibrinogen was excluded by examining the submicrosecond time-resolved fluorescence depolarization of 1-methylpyrene conjugates of the protein in the presence of different calcium concentrations. Although there are inherent difficulties to extrapolate the data on isolated fibrinogen molecules to the polymerizing species, this relatively stiff conformation meets the requirements of the classical half-staggered double-stranded model of fibrin polymerization rather better than those of the recently proposed interlocked single-stranded mechanism.     

Potato Virus X—a New Report from Turnip (Brassica rapa L.) in India

A virus isolated from turnip in Aligarh, India, which caused mild mosaic, mottling and curling of leaves followed by overall stunting of plants, was characterized as potato virus X (PVX) on the basis of its host range, biological and physical properties, particle morphology, ultrastructural studies, and serological relationship.     

Protein structure probed by polarization spectroscopy. II. A time-resolved fluorescence study of human fibrinogen

Human fibrinogen in solution was studied by monitoring the time-resolved depolarization of the fluorescence emitted by two spectroscopic labels of which the fluorescence lifetimes differ by an order of magnitude. Contrary to a long-held view, no evidence of molecular flexibility was found in the 10-1000 ns range. In addition, from the rate of the overall rotation, it is proposed that a prolate and symmetric ellipsoid of 47 X 10.5 nm may represent the time-averaged hydrodynamic size and shape of the protein in solution. This rigid and highly hydrated structure (4 g water/g protein) accommodates the latest nodular models obtained from electron microscopy, explains the singular hydrodynamics of fibrinogen and, apparently, it would perform the two main functions of the protein in haemostasis, blood coagulation and platelet aggregation, more efficiently than the flexible molecule.     

Promoter diversity in multigene transformation

Multigene transformation (MGT) is becoming routine in plant biotechnology as researchers seek to generate more complex and ambitious phenotypes in transgenic plants. Every nuclear transgene requires its own promoter, so when coordinated expression is required, the introduction of multiple genes leads inevitably to two opposing strategies: different promoters may be used for each transgene, or the same promoter may be used over and over again. In the former case, there may be a shortage of different promoters with matching activities, but repetitious promoter use may in some cases have a negative impact on transgene stability and expression. Using illustrative case studies, we discuss promoter deployment strategies in transgenic plants that increase the likelihood of successful and stable multiple transgene expression.     

Synaptotagmin II and Gangliosides Bind Independently with Botulinum Neurotoxin B but Each Restrains the Other

Botulinum neurotoxin type B (BoNT/B) initiates its toxicity by binding to synaptotagmin II (SytII) and gangliosides GD1a and GT1b on the neural membrane. We synthesized two 27-residue peptides that carry the BoNT/B binding sites on mouse SytII (mSytII 37–63) or human SytII (hSytII 34–60). BoNT/B bound to these peptides, but showed substantially higher binding to mSytII peptide than to hSytII peptide. The mSytII peptide inhibited almost completely BoNT/B binding to synaptosomes (snps) and displayed a high affinity. BoNT/B bound strongly to mSytII peptide and binding was inhibited by the peptide. Binding of BoNT/B to snps was also inhibited (~80 %) by a larger excess of gangliosides GD1a or GT1b. The mSytII peptide inhibited very strongly (at least 80 %) the toxin binding to snps, while the two gangliosides were much less efficient inhibitors requiring much larger excess to achieve similar inhibition levels. Furthermore, gangliosides GD1a or GT1b inhibited BoNT/B binding to mSytII peptide at a much larger excess than the inhibition by mSytII peptide. Conversely, BoNT/B bound well to each ganglioside and binding could be inhibited by the correlate ganglioside and much less efficiently by the mSytII peptide. There was no apparent collaboration between mSytII peptide and either ganglioside. mSytII peptide displayed some protective activity in vivo in mice against a lethal BoNT/B dose. We concluded that SytII peptide and gangliosides bind independently but, with their binding sites on BoNT/B being spatially close, each can influence BoNT/B binding to the other due to regional conformational perturbations or steric interference or both. Ganglioside involvement in BoNT/B binding might help in toxin translocation and endocytosis.     

Denitrifying Bacterial Community Composition Changes Associated with Stages of Denitrification in Oxygen Minimum Zones

Denitrification in the ocean is a major sink for fixed nitrogen in the global N budget, but the process is geographically restricted to a few oceanic regions, including three oceanic oxygen minimum zones (OMZ) and hemipelagic sediments worldwide. Here, we describe the diversity and community composition of microbes responsible for denitrification in the OMZ using polymerase chain reaction, sequence and fragment analysis of clone libraries of the signature genes (nirK and nirS) that encode the enzyme nitrite reductase, responsible for key denitrification transformation steps. We show that denitrifying assemblages vary in space and time and exhibit striking changes in diversity associated with the progression of denitrification from initial anoxia through nitrate depletion. The initial denitrifying assemblage is highly diverse, but succession on the scale of 3–12 days leads to a much less diverse assemblage and dominance by one or a few phylotypes. This progression occurs in the natural environment as well as in enclosed incubations. The emergence of dominants from a vast reservoir of rare types has implications for the maintenance of diversity of the microbial population and suggests that a small number of microbial dominants may be responsible for the greatest rates of transformations involving nitrous oxide and global fixed nitrogen loss. Denitrifying blooms, driven by a few types responding to episodic environmental changes and distributed unevenly in time and space, are consistent with the sampling effect model of diversity–function relationships. Canonical denitrification thus appears to have important parallels with both primary production and nitrogen fixation, which are typically dominated by regionally and temporally restricted blooms that account for a disproportionate share of these processes worldwide.     

Human health risks of metals and metalloids in muscle tissue of Synodontis zambezensis Peters, 1852 from Flag Boshielo Dam,South Africa

Muscle tissue from 63 Synodontis zambezensis collected bimonthly in 2013 at Flag Boshielo Dam were analysed for metals and metalloids in a desktop human health risk assessment. The Hazard Quotient, based on a weekly meal of 67 g of fish muscle, exceeded the maximum acceptable level of one for lead, cobalt, cadmium, mercury, arsenic and selenium. The concentrations of these elements were higher in 2013 than those recorded in 2009 and 2012 in other fish species from Flag Boshielo Dam and these may pose a long-term health risk if consumed regularly by impoverished rural communities reliant on fish as a source of protein.