Evaluation of the single radial-immunodiffusion assay for measuring the glycoprotein content of rabies vaccines

The glycoprotein content of rabies vaccines containing the Pitman-Moore strain of rabies virus was measured by the single radial immunodiffusion assay and correlated with vaccine potency. The variability of this assay was 6.3% for a single vaccine lot tested over a one-year period. Using sera prepared against rabies virus glycoprotein from different strains of virus, the assay gave different values. These differences could be eliminated by using a homologous vaccine strain as an internal reference. Single radial-immunodiffusion values for Pitman-Moore vaccines correlated with the manufacturers' NIH potency assay, but required a mathematical transformation to convert values from one assay to the other. Single radial-immunodiffusion values for Street Alabama Dufferin and Flury-LEP vaccines did not correlate with NIH values. Modification of the single radial immunodiffusion technique and the feasibility of using this assay for the determination of rabies vaccine potency are discussed.     

Age-specific Chaoborus predation on rotifer prey

SUMMARY. 1. This is the first study to examine predator-prey interactions between Chaoborm instars and rotifer prey. The predatory behaviour of instars I–III of Chaoborus pimctipennis and the diet selectivity of instars I—IV feeding on rotifers were examined in the laboratory. Prey used in direct observations of predatory behaviour included a variety of rotifers (Symhacta pectlnata, S. ohUmga, Polyarthra remata, Asplanchna girodi, Keratella crassa, spined and unspined forms of Keratella cochlearis) and two crustaceans (Bosmitia longirostris, Mesocyclops edax nauplii. 2. In general, strike efficiencies (percentage of strikes resulting in inges- tion) increased in successive instars I—III. Early instar (I and II) strike efficiencies were low when compared with other invertebrate predators. For a given instar. mean prey handling times varied among prey species more than strike efficiencies. Mean handling times for small, soft-bodied rotifers were lowest and those for wide, hard-bodied prey were highest. 3. Instar I exhibited significantly greater selectivity for the small, soft- bodied S. obUmga than for the larger S. pectinata, hard-bodied K. crassa, and spined and unspined forms of K. cochlearis. Instars II—IV positively selected both the large and small Symhaeta species over all Keratella species. The relationship between Chaobortts selectivity and prey value (weight of prey per unit handling time) can be described by a power function. Ingestion rates of rotifers by older instars (III and IV) are among the highest reported for invertebrate predators. 4. Rotifer vulnerability to Chaoborus predation probably depended on rotifer cuticle texture, body width, and hydrodynamic disturbances. Spined rotifers were not necessarily protected from Chaoborus predation because Chaohorus can manipulate and swallow them. Giguere et al.'s 1982) encounter rate model must be modified to predict encounter rates of slow-moving rotifer prey with Chaohorus.     

Short-term movements of chalk-stream invertebrates

SUMMARY 1. Trays of gravel were implanted for 24 h periods in several chalk streams. The trays were variously modified to monitor colonization from different sources, particularly drift (D), other downstream movements (DSM), upstream movements (USM), and all sources combined (ALL).
2. The abundance of invertebrates in the streams was high (maximum of 717 per 0.04 m²) and colonization of the trays was extensive, especially by Gammarus pulex , the predominant species in all but one of the streams (maximum number of individuals of G. pulex per tray: for D, 473; for DSM, 462; tor USM, 286; and tor ALL, 639). In some cases benthic densities were achieved in the trays in the 24 h exposure period, and in most cases any one source of colonization could provide benthic densities in a few days.
3. Patterns of movement differed between species, between size classes of G. pulex , and between sites for particular species. No one source of colonization could be regarded as generally predominant although downstream movements in total (D + DSM) usually far exceeded USM. DSM was usually an important source of colonization.
4. The extent and direction of movement appeared to be determined by local factors and were explained in terms of the high densities of invertebrates and the current and substratum characteristics of each site.
5. Estimates of the relative importance of different sources of colonization varied greatly according to the criteria used in determining proportions.     

Short- and long-term effects of proallatotoxin (ethoxyprecocene II) on Rhodnius prolixus females

Oogenesis and oviposition can be inhibited in female of Rhodnius prolixus by means of short-term experiment (first reproductive cycle) of a single dose of ethoxyprecocene II given by ingestion. The inhibition is dose-dependent as measured by oocyte growth, egg maturation and egg deposition. In a long-term experiment (second and third reproductive cycles) egg production and oogenesis can be partially or totally re-established by subsequent blood meals without ethoxyprecocene II. These findings suggest that in female R. prolixus, damage caused to corpus allatum by ethoxyprecocene II, in certain cases, is not irreversible.     

Preparation of scirpentriol and triacetoxyscirpenol in good yield from cultures of Fusarium sambucinum NRRL 13495

Crude extracts of filtrates of cultures of Fusarium sambucinum NRRL 13495 were acetylated or hydrolyzed. After chromatography on cartridge columns of silica gel and recrystallization three times from mixtures of ethyl acetate and hexane, 3,4,15-triacetoxyscirpenol (435 +/- 10 mg/liter of filtrate; mean +/- standard error [n = 3]) and the parent alcohol scirpentriol were isolated (261 +/- 29 mg/liter of filtrate; mean +/- standard error [n = 3]) in 68 and 53% yield for a 130- and 14-fold improvement, respectively, over prior reports.     

Construction of DNA-probes and their immunochemical detection using nonradioactive hybridization tests

Simple and efficient chemical approaches to preparation of DNA probes carrying 2,4-dinitrophenyl, dansyl or biotin residues were developed. The residues were introduced using following DNA derivatization procedures: a) transamination of cytidine residues with O-(4-aminobutyl)hydroxylamine; b) mercuration of pyrimidine residues followed by beta-mercaptoethanol modification. It was shown that 2,4-dinitrophenyl-containing DNA probes can be used for nonradioactive hybridization detection of nucleic acids. DNP-DNA: DNA complexes were detected using mouse antibodies specific to 2,4-dinitrophenyl groups, which were developed with peroxidase-conjugated antimouse immunoglobulins. Peroxidase-catalyzed chemoluminescent reaction of luminol oxidation with hydrogen peroxide allowed to detect 10 picograms of the dinitrophenylated single-stranded DNA probe.     

Determination of interproton distances in peptides by two-dimensional nuclear Overhauser effect spectroscopy (NOESY). Conformation of a cyclic analog of substance P in a solution

Quantitative method is developed for evaluation interproton distances in peptides in solution. The method is based on the measurement of the relative intensities of the cross-peaks in the pure-phase absorption NOESY spectra. The ratios of the cross-peak intensities IN alpha/I alpha N and INN/I alpha N enable to determine the corresponding interproton distances dN alpha, d alpha N and dNN for several amino acid residues. These distances can be used to estimate other distances with cross-peaks in NOESY spectra. As example, the interproton distances are determined in a cyclic hexapeptide, namely cyclic analogue of substance P: cyclo [H-Glu-Phe-Phe-Gly-Leu-Met-NH(CH2)3-NH-]. The spatial structure of the molecule in dimethylsulphoxide solution is established.     

Functionally important lysine residues in inorganic pyrophosphatase from E. coli. II. Isolation and characteristics of modified tryptic peptide and analysis of the functional role of lysine residues controlling enzyme activity

Inactivation of inorganic pyrophosphatase from E. coli by pyridoxal-5'-phosphate is due to the modification of a lysine residue located in the tryptic peptide with the Asp-Leu-Pro-Glu N-terminal sequence. In course of the enzymatic process this lysine-residue appears to be in the protonated state and either operators as the proton donor for the product of the enzymatic reaction or is involved in stabilization of the transition state.     

Pheophytin-mediated energy storage of photosystem II particles detected by photoacoustic spectroscopy

The photoacoustic (PA) characteristics (energy storage and heat dissipation) of photosystem II (PSII) core-enriched particles from barley were studied (i) in conditions where there was electron flow, i.e., in the presence of a combination of the electron acceptor K₃ Fe (CN)₆, referred to as FeCN, and the electron donor diphenylcarbazide (DPC), and (ii) in conditions where electron flow was suppressed, i.e., in the absence of FeCN and DPC. The experimental data show that a decrease of heat dissipation with a minimum at 540 nm can be interpreted as energy storage resulting from the presence of pheophytin (Pheo) in the PSII particles. On account of the capability of the PA method to measure the energy absorbed by the chromophores which is converted to heat, it is suggested that the PA detection of Pheo present in the PSII complex will permit to clarify the function of processes involving non-radiative relaxation of excited states in P680-Pheo-Q_A interactions.Abbreviations -Car -Carotene - Chl Chlorophyll - DPC Diphenylcarbazide - EPR Electron Paramagnetic Resonance - FeCN potassium ferricyanide - HEPES N-2-hydroxyethylenepiperazine-N-2-ethanesulfonate - P680 reaction center of PSII - PA Photoacoustic - Pheo pheophytin - PSI photosystem I - PSII photosystem II - Q_A primary electron acceptor of PSII