Low levels of hybridization in two species of African driver ants.

Hybridization in ants can have consequences different from those observed in most other species, with many of the potential deleterious effects being mitigated due to haplodiploidy and eusociality. In some species where colonies are either headed by multiple queens or single queens that mate with many males, hybridization is associated with genetic caste determination, where hybrids develop into workers and purebred individuals develop into queens. A previous study suggested that hybridization occurs between two Dorylus army ant species with multiply mated queens. However, the extent and exact pattern of hybridization have remained unclear, and its possible effect on caste determination has not been investigated. In this study, we aimed to determine the extent and direction of hybridization by measuring how frequently hybrids occur in colonies of both species, and to investigate the possibility of genetic caste determination. We show that hybridization is bidirectional and occurs at equal rates in both species. Hybrid workers make up only 1-2% of the population, and successful interspecific matings represent approximately 2% of all matings in both species. This shows that, although interspecific matings that give rise to worker offspring occur regularly, they are much rarer than intraspecific mating. Finally, we find no evidence of an association between hybridization and genetic caste determination in this population. This means that genetic caste determination is not a necessary outcome of hybridization in ants, even in species where queens mate with multiple males.

[The use of the plasmid pTH10 for isolating the donor strains of Pseudomonas mallei]. / Primenenie plazmidy pTH10 dlia polucheniia donornykh shtammov Pseudomonas mallei.

The plasmid pTH10 was transfered by conjugation into the Pseudomonas mallei strains. An attempt to construct the donor strains using the widely known technique employing the homology between the plasmid and chromosome due to the transposon Tn1 carried by the plasmid was unsuccessful. Among the clones resistant to bacteriophage PRD1 the variants were selected with the supposed integration of the plasmid into the chromosome. The latter clones required the ability to transfer the auxotrophic chromosomal markers in conjugation after the repeated conjugational transfer of the plasmid pTH10 into them.

Antiestrogens. 2. Structure-activity studies in a series of 3-aroyl-2-arylbenzo[b]thiophene derivatives leading to [6-hydroxy-2-(4-hydroxyphenyl)benzo[b]thien-3-yl] [4-[2-(1-piperidinyl)ethoxy]-phenyl]methanone hydrochloride (LY156758), a remarkably effective estrogen antagonist with only minimal intrinsic estrogenicity.

In an effort to prepare nonsteroidal antiestrogens demonstrating greater antagonism and less intrinsic estrogenicity than those currently available, a series of 3-aroyl-2-arylbenzo[b]thiophene derivatives was synthesized. These compounds were prepared by Friedel-Crafts aroylation of appropriate O-protected 2-arylbenzo[b]thiophene nuclei with basic side-chain-bearing benzoyl chlorides followed by removal of the protective groups to provide the desired compounds containing both hydroxyl and basic side-chain functionality. A particularly useful method for the cleavage of aryl methoxy ethers without removal of (dialkylamino)ethoxy side chain functionality elsewhere in the molecule was found to be AlCl3/EtSH. The benzothiophene derivatives were tested for their ability to inhibit the growth-stimulating action of estradiol on the immature rat uterus. Seemingly minor changes in the side-chain amine moiety were found to have profound effects on the ability of the compounds to antagonize estradiol. Analogues having basic side chains containing cyclic (pyrrolidine, piperidine, and hexamethyleneamine) moieties were found to have less intrinsic estrogenicity and to antagonize estradiol action more completely than their noncyclic counterparts. The most effective antiestrogen in the series, compound 44, [6-hydroxy-2-(4-hydroxyphenyl)benzo[b] thien-3-yl]-[4-[2-(1-piperidinyl)ethoxy]phenyl]methanone, elicited a modest uterotropic activity that did not increase with increasing dose. In antagonism of estradiol, 44 exhibited a degree of inhibition surpassing that of tamoxifen at any dose tested. The new benzothiophene antiestrogen was also shown to have high affinity for rat uterine cycloplasmic estrogen receptor and to be an inhibitor of the growth of DMBA-induced rat mammary tumors.

[The nature of changes in the antigenic spectrum of the causative agent of melioidosis during animal passage]. / Kharakter izmenenii antigennogo spektra vozbuditelia melioidoza pri passirovanii na zhivotnykh.

The comparative analysis of the antigenic spectra of Pseudomonas pseudomallei museum and subcultured strains, carried out by the method of immunoelectrophoresis, has revealed that, along with an essential increase in the virulence of P. pseudomallei for white mice and changes in the morphology of colonies, a decrease in the amount of detected precipitinogens occurs in the process of subculturing. The immunoelectrophoregrams of the subcultured variants show the absence of antigens 5, 6 and the simultaneous increase of the production of antigen 8, one of the components of mucoid (in the pseudocapsule).

Temperature profiles in nitrous oxide supported acetylene flames at atmospheric pressure.

Temperature profiles have been established at three mixture strengths of the nitrous oxide-acetylene flame used in atomicabsorption spectroscopy. Measurement of the electronic excitation temperature of the red-feather zone by the sodium line-reversal and iron two-line methods yields average maximum temperatures of 3070 and 3025 +/- 50 degrees K respectively. This is significantly lower than the only previously reported value, 3228 degrees K. Other temperature measurements obtained by studying intensity distribution of NH rotational fine structure and CN vibrational structure yielded less precise results, but suggest a state of thermal equilibrium in the flame. The temperature gradient within the flame shows a steady decrease with height above the primary zone. A study of CN spectra and the zones of persistence of free atoms and of metal oxide species suggests a mechanism of free atom production within the cyanogen zone whereby the removal of oxidizing radicals by CN promotes dissociation of metal oxide species previously formed in the primary zone of the flame.

Emission spectra of nitrous oxide supported acetylene flames at atmospheric pressure.

The emission spectra of a premixed flame of acetylene supported by nitrous oxide have been recorded under different fuel-gas mixture conditions. The emission spectra in these flames of a series of metals, for which it is difficult to obtain a significant population of ground state atoms for atomic absorption spectroscopy in more conventional flames, have also been studied. The red secondary zone which is present in the fuel-rich flames shows emission attributable to long-lived CN and NH species which form a strongly reducing atmosphere to inhibit refractory oxide formation from elements such as molybdenum, titanium and aluminium introduced into the flame. An attempt has also been made to explain some of the reactions which may occur between the flame species above the primary reaction zone.