Vibration Signal Behavior of Waggle-dancers in Swarms of the Honey Bee,Apis mellifera (Hymenoptera: Apidae)

We hypothesize two functions of the vibration signal (dorsal ventral abdominal vibration = DVAV) during swarming in honey bees: 1. it enhances recruitment to the specific sites advertised by the waggle dancers which also perform the vibration signal; and 2. it acts as a nonspecific modulatory signal to stimulate activity in other bees. The stimulation of activity invoked by the second hypothesis might include increasing nest-site scouting and dance following early in the house-hunting process or rousing quiescent bees to prepare them for lift-off late in the process, or both. In studies of neotropical African bee swarms in Costa Rica and European bees in California we tested these hypotheses by looking for associations between production of vibration signals by nest-site recruiters and site attractiveness (indicated by which site was ultimately chosen and by distance from the swarm since swarms may have a distance preference). Overall, bees dancing for the chosen sites performed vibration signals to the same extent as those dancing for the other sites. There were no distance differences between sites whose scouts did and did not vibrate other bees. These results are inconsistent with the hypothesis that the vibration signal enhances recruitment to especially high quality sites and they support the hypothesis that it plays a general excitatory role in the context of house hunting by swarming bees.     

Template-directed synthesis of acyclic oligonucleotide analogues

Bis-phosphoimidazolides of an analogue of adenosine (in which ribose is replaced by an acyclic chain) and of two related analogues of guanosine undergo oligomerization in the presence of complementary polynucleotide templates. Data on the template- and nontemplate-directed reactions are presented, and the possible relevance to origins of life is discussed.     

A simplified purification method for the analysis of abscisic acid

A fast and convenient method is given for the purification of abscisic acid (ABA) in plant extracts. Using a dual pH elution system on Sep-Pak C18 reverse phase prepacked cartridges, abscisic acid appears in the third eluent (32% methanol pH 8.0). The cartridges can be regenerated for multiple reuse.     

Parental assignment in fish using microsatellite genetic markers with finite numbers of parents and offspring

Deterministic predictions for the proportion of offspring assigned to different numbers of parent-pairs are developed in order to investigate the power of microsatellite loci for parental assignment in fish species. Comparisons with stochastic simulation results show that predictions based on exclusion probabilities are accurate, provided that the number of parents involved in the crosses is large. Accounting for sampling of parents gave very accurate predictions for a small number of parents and a single biallelic locus. For large numbers of loci or large numbers of alleles per locus stochastic simulations are, however, the only available method to predict the power of assignment of a particular set of loci when the number of parents is small. Nine 5-allele loci or six 10-allele loci with equifrequent alleles, are sufficient for assigning, with certainty, parents to 99% of the fish resulting from either 100 or 400 crosses. Results simulating a set of highly polymorphic microsatellites developed for Atlantic salmon show that the four most informative loci are sufficient to assign at least 99% of the offspring to the correct pair with 100 crosses involving 100 males and 100 females. An additional locus is required for correctly assigning 99% of the offspring when the 100 crosses are produced with 10 males and 10 females.     

Four-parameter white blood cell differential counting based on light scattering measurements

Measurement of the depolarized orthogonal light scattering in flow cytometry enables one to discriminate human eosinophilic granulocytes from neutrophilic granulocytes. We use this method to perform a four-parameter differential white blood cell analysis. A simple flow cytometer was built equipped with a 5-mW helium neon laser that measures simultaneously four light scattering parameters. Lymphocytes, monocytes, and granulocytes were identified by simultaneously measuring the light scattering intensity at angles between 1.0 degrees and 2.6 degrees and angles between 3.0 degrees and 11.0 degrees. Eosinophilic granulocytes were distinguished from neutrophilic granulocytes by simultaneous measurement of the orthogonal and depolarized orthogonal light scattering. Comparison of a white blood cell differentiation of 45 donors obtained by the Technicon H-6000 and our instrument revealed good correlations. The correlation coefficients (r2) found were: 0.99 for lymphocytes, 0.76 for monocytes, 0.99 for neutrophilic granulocytes, and 0.98 for eosinophilic granulocytes. The results demonstrate that reliable white blood cell differentiation of the four most clinically relevant leukocytes can be obtained by measurement of light scattering properties of unstained leukocytes.     

Molecular evolution of bacteriophages: evidence of selection against the recognition sites of host restriction enzymes

Restriction enzymes produced by bacteria serve as a defense againstinvading bacteriophages, and so phages without other protection would beexpected to undergo selection to eliminate recognition sites for theseenzymes from their genomes. The observed frequencies of all restrictionsites in the genomes of all completely sequenced DNA phages (T7, lambda,phi X174, G4, M13, f1, fd, and IKe) have been compared to expectedfrequencies derived from trinucleotide frequencies. Attention was focusedon 6-base palindromes since they comprise the typical recognition sites fortype II restriction enzymes. All of these coliphages, with the exception oflambda and G4, exhibit significant avoidance of the particular sequencesthat are enterobacterial restriction sites. As expected, the sequencedfraction of the genome of phi 29, a Bacillus subtilis phage, lacks Bacillusrestriction sites. By contrast, the RNA phage MS2, several viruses thatinfect eukaryotes (EBV, adenovirus, papilloma, and SV40), and threemitochondrial genomes (human, mouse, and cow) were found not to lackrestriction sites. Because the particular palindromes avoided correspondclosely with the recognition sites for host enzymes and because otherviruses and small genomes do not show this avoidance, it is concluded thatthe effect indeed results from natural selection.     

Isolation, Growth, and Metabolism of an Obligately Anaerobic, Selenate-Respiring Bacterium, Strain SES-3

A gram-negative, strictly anaerobic, motile vibrio was isolated from a selenate-respiring enrichment culture. The isolate, designated strain SES-3, grew by coupling the oxidation of lactate to acetate plus CO₂ with the concomitant reduction of selenate to selenite or of nitrate to ammonium. No growth was observed on sulfate or selenite, but cell suspensions readily reduced selenite to elemental selenium (Se⁰). Hence, SES-3 can carry out a complete reduction of selenate to Se⁰. Washed cell suspensions of selenate-grown cells did not reduce nitrate, and nitrate-grown cells did not reduce selenate, indicating that these reductions are achieved by separate inducible enzyme systems. However, both nitrate-grown and selenate-grown cells have a constitutive ability to reduce selenite or nitrite. The oxidation of [¹⁴C]lactate to ¹⁴CO₂ coupled to the reduction of selenate or nitrate by cell suspensions was inhibited by CCCP (carbonyl cyanide m-chlorophenylhydrazone), cyanide, and azide. High concentrations of selenite (5 mM) were readily reduced to Se⁰ by selenate-grown cells, but selenite appeared to block the synthesis of pyruvate dehydrogenase. Tracer experiments with [⁷⁵Se]selenite indicated that cell suspensions could achieve a rapid and quantitative reduction of selenite to Se⁰. This reduction was totally inhibited by sulfite, partially inhibited by selenate or nitrite, but unaffected by sulfate or nitrate. Cell suspensions could reduce thiosulfate, but not sulfite, to sulfide. These results suggest that reduction of selenite to Se⁰ may proceed, in part, by some of the components of a dissimilatory system for sulfur oxyanions.