Effect of IFN-γ receptor gene deletion on vaccinia virus virulence

Summary.  Two vaccinia virus (VV) strains, WR and Praha, were selected for a study undertaken to determine whether the virus-encoded interferon-γ receptor (IFN-γR) plays any role in virus virulence. Both of the viruses expressed the B8R gene coding for IFN-γR in infected cell cultures. The nucleotide sequence of the Praha virus B8R gene was determined, and, when compared with the published sequence of the WR virus, it only displayed one silent nucleotide substitution. Mutants of the WR and Praha viruses with deleted B8R gene were constructed. In rabbits, skin lesions produced by the WR B8R-deleted mutants were smaller and tended to disappear earlier than those caused by wild-type WR virus. Similar results were obtained with both independently prepared WR B8R-deleted mutants. These data strongly suggested that the product of B8R gene did play a role in virus virulence. A similar comparison of the wild-type Praha virus and its mutant could not be done because of the very low virulence of the parental virus for rabbits. Received March 13, 2000 Accepted August 16, 2000     

Effects of adrenalectomy and gonadectomy on sex and stress-induced differences in bicuculline-induced convulsions

The effects of adrenalectomy, gonadectomy and combined adrenalectomy plus gonadectomy on the previously described sex-dependent anticonvulsive effect of swim stress were studied in rats. The convulsive signs (myoclonic twitch, generalized convulsions, tonic hindlimb extension) were produced by constant i.v. infusion of γ-aminobutyric acid_A (GABA_A) antagonist bicuculline, which started 15 min after termination of swim stress (10-min swim at 18–19°C). Adrenalectomy decreased the threshold doses of bicuculline producing the first myoclonic twitch and the onset of generalized convulsions only in females. In adrenalectomized females, but not in males, swim stress enhanced the threshold dose of bicuculline producing generalized convulsions, but, unlike in adrenal-intact animals, it failed to enhance the dose of bicuculline producing tonic hindlimb extension. In gonadectomized stressed and unstressed animals all sex differences disappeared, and swim stress enhanced in both sexes only the threshold doses of bicuculline producing tonic hindlimb extension. Adrenalectomized plus gonadectomized animals displayed clear sex differences in doses of bicuculline necessary to produce all the convulsive signs. In the same animals swim stress postponed, especially in females, the onset of the first myoclonic twitch and generalized convulsions, but not the onset of tonic hindlimb extension. In summary, our results suggest that hormones of the adrenal and gonadal glands are only partly responsible for decreased susceptibility, especially of female rats, to the GABA_A antagonist bicuculline. Moreover, they have demonstrated that stress produces a gender-specific anticonvulsive effect even in the animals completely deprived of steroid hormones of peripheral origin. Received: 4 June 1998 / Accepted: 11 June 1999     

Rapid diagnosis of parasitic diseases: current scenario and future needs

Background

Parasitic diseases are one of the world's most devastating and prevalent infections, causing millions of morbidities and mortalities annually. In the past, many of these infections have been linked predominantly to tropical or subtropical areas. Nowadays, however, climatic and vector ecology changes, a significant increase in international travel, armed conflicts, and migration of humans and animals have influenced the transmission of some parasitic diseases from ‘book pages’ to reality in developed countries. It has also been noted that many patients who have never travelled to endemic areas suffer from blood-borne infections caused by protozoa. In the light of existing knowledge, this new trend can be explained by the fact that in the process of migration a large number of asymptomatic carriers become a part of the blood bank donor and transplant donor populations. Accurate and rapid diagnosis represents the crucial weapon in the fight against parasitic infections.

Can a part of an inducer become incorporated into interferon?

Highly purified and concentrated interferons obtained from L cells or from mouse peritoneal leukocytes (MPL) after induction with³H-uridin labeled double-stranded RNA of f₂ phageE. coli (phage ds-RNA) were analysed by poly-acrylamide gel electrophoresis. A coincidence of the discrete radioactivity peak with one of the interferon activity peaks was demonstrated.     

Effects of melanotan II,a melanocortin agonist,on grooming and exploration in rats after repeated restraint/immobilization

2 mg/kg melanotan II (MTII, administered i.p.), a cyclic peptide analog of α-melanocyte stimulating hormone, at a single dose increased grooming in naive rats placed in an unfamiliar open-field device without changing locomotion or rearing. Male rats exposed to restraint/immobilization stress (IS) for 1 h on three consecutive days displayed increased grooming after the second stressor exposure, compared to pre-stress levels. MTII, administered to the rats after IS, enhanced the grooming response compared both to the pre- and post-stress values. The increase was greatest after the first dose and declined over the following two applications. As to the locomotion of rats in the entire experimental space, IS reduced the distance moved only after the first two stressor exposures; MTII did not influence these alterations. Locomotion in the central part of arena was not reduced by the stressor or by MTII, on the contrary, there was an increase in both groups after the third intervention. The only observed change in rearing was an increase in the MTII group after the third restraint exposure. Thus, MTII selectively increased grooming without markedly affecting the spatio-temporal structure of locomotor behavior in the open-field. The decline of MTII enhanced grooming over the three test days may be interpreted in terms of adaptation to the stressor and of the developing tolerance to the peptide.     

Development of flow cytogenetics and physical genome mapping in chickpea (Cicer arietinum L.)

Procedures for flow cytometric analysis and sorting of mitotic chromosomes (flow cytogenetics) have been developed for chickpea (Cicer arietinum). Suspensions of intact chromosomes were prepared from root tips treated to achieve a high degree of metaphase synchrony. The optimal protocol consisted of a treatment of roots with 2mmol/L hydroxyurea for 18h, a 4.5-h recovery in hydroxyurea-free medium, 2h incubation with 10µmol/L oryzalin, and ice-water treatment overnight. This procedure resulted in an average metaphase index of 47%. Synchronized root tips were fixed in 2% formaldehyde for 20min, and chromosome suspensions prepared by mechanical homogenization of fixed root tips. More than 4×10⁵ morphologically intact chromosomes could be isolated from 15 root tips. Flow cytometric analysis of DAPI-stained chromosomes resulted in histograms of relative fluorescence intensity (flow karyotypes) containing eight peaks, representing individual chromosomes and/or groups of chromosomes with a similar relative DNA content. Five peaks could be assigned to individual chromosomes (A, B, C, G, H). The purity of sorted chromosome fractions was high, and chromosomes B and H could be sorted with 100% purity. PCR on flow-sorted chromosome fractions with primers for sequence-tagged microsatellite site (STMS) markers permitted assignment of the genetic linkage group LG8 to the smallest chickpea chromosome H. This study extends the number of legume species for which flow cytogenetics is available, and demonstrates the potential of flow cytogenetics for genome mapping in chickpea.     

Neuropeptide Y in the female reproductive tract of the rat. Distribution of nerve fibres and motor effects

The spontaneous firing of single neurones in the region of the lateral reticular nucleus was the subject of a pharmacological study employing microiontophoretic and systemic application of adrenoceptor agonists and antagonists. Both iontophoretic noradrenaline and systemic clonidine depressed neuronal firing. The depressions were consistently reversed by the alpha-2 antagonist RX781094. Other adrenergic antagonists, prazosin and sotalol, were ineffective. The results suggest the existence of alpha-2 receptors in this region of the brain.