Genetic Analysis of tox+ and tox? Bacteriophages of Corynebacterium diphtheriae

A series of mutants derived from the temperate corynebacteriophages beta(tox+), gamma(tox-), and L(tox+) was isolated and characterized. In three-factor crosses between mutant beta phages the relative map order of the genetic markers determining extended host ranges (h and h') and loss of ability to lysogenize (c) was found to be h--c--h'. Recombination between markers was observed in matings between phage beta and the heteroimmune corynebacteriophages gamma and L. In such matings between heteroimmune phages the c markers of phages beta and gamma failed to segregate from the imm markers which determine the specificity of lysogenic immunity in these phages. The factor which directs the synthesis of diphtherial toxin during infection of appropriate corynebacterial hosts by toxinogenic corynebacteriophages is designated tox(+). It was possible to show that the tox(+) determinant of phage beta behaves as a single genetic element which occupies a position between the loci h and imm on the genetic map of this phage. Genetic recombination between mutants of phage beta occurred at very low frequencies in biparental matings performed by mixed infection of Corynebacterium diphtheriae C7(s)(-)(tox-). Considerably higher recombination frequencies were observed when lysogenic bacterial strains carrying one parental phage as prophage were induced by ultraviolet irradiation and then superinfected by the second parental phage. Maximal stimulation of genetic recombination between mutant beta phages was detected when superinfection followed ultraviolet irradiation of the lysogenic cells within a limited period of time. In matings between phages with incomplete genetic homology, the stimulation of recombination by ultraviolet radiation was much less effective.     

System for the Investigation of the Bacteriophage-directed Synthesis of Diphtherial Toxin

Lytic corynebacteriophage betahv64(tox+) has been characterized, and methods for studying the expression of its tox(+) gene in nontoxinogenic Corynebacterium diphtheriae strain C7(s)(-)(tox-) described. During one cycle of viral growth there was a 1 million-fold increase in extracellular toxin. Both the conditions of the experiment and the use of purified phage, free from toxin, support the conclusion that all of the toxin was newly formed. This toxin was immunochemically indistinguishable from standard toxin produced by the PW8(r)(Pdi)(tox+) strain. Chloramphenicol was found to be an effective agent for synchronizing the initiation of viral growth. Once chloramphenicol was removed, intracellular toxin appeared and continued to increase throughout the latent period. Proflavine, added early in the latent period, blocked phage maturation without similarly affecting yields of toxin. Iron exerted a limited inhibitory effect on final toxin levels attained.     

Differentiation-specific expression from the bovine papillomavirus type 1 P2443 and late promoters.

The papillomavirus life cycle is tightly linked with keratinocyte differentiation in squamous epithelia. Vegetative viral DNA replication begins in the spinous layer, while synthesis of capsid proteins and virus maturation is restricted to the most differentiated or granular layer of the epithelium. In this study, in situ hybridization of bovine fibropapillomas was used to demonstrate that the activity of two promoters of bovine papillomavirus type 1 (BPV-1) is regulated in a differentiation-specific manner. In situ hybridization with a late promoter (PL)-specific oligonucleotide probe suggested that PL is dramatically upregulated in the granular layer of the fibropapilloma. Northern (RNA) blot analysis of RNA from BPV-1-infected fibropapillomas indicated that the three major BPV-1 late-region mRNAs were transcribed from PL. These RNAs include the previously described L1 (major capsid) mRNA as well as two larger mRNAs. The two larger mRNAs were characterized and shown to contain the L2 (minor capsid protein) open reading frame as well as the L1 open reading frame. In contrast to PL, the P2443 promoter was maximally active in basal keratinocytes and the fibroma. The major mRNA transcribed from P2443 is the putative E5 oncoprotein mRNA which is spliced between nucleotides 2505 and 3225. No signal was detected above the basal layer with use of a probe specific for this mRNA. The E5 oncoprotein has previously been localized by immunoperoxidase staining to the granular cell layer as well as the basal cell layer of the fibropapilloma (S. Burnett, N. Jareborg, and D. DiMaio, Proc. Natl. Acad. Sci. USA 89:5665-5669, 1992). These data suggest that E5 proteins in the basal cell and granular cell layers are not translated from the same mRNA.     

Seed transmission of turnip yellow mosaic virus in winter turnip and winter oilseed rapes

This is the first record of seed transmission of turnip yellow mosaic virus (TYMV) in oilseed and turnip rapes. The seed transmission of TYMV in a naturally infected winter turnip rape (Brassica napus var. silvestris) cultivar Perko PVH was investigated. By ELISA 1.6%, 3.2% and 8.3% seed transmission of the virus was found in seed of plants from three localities. The proportion of infected seeds produced by artificially infected plants of winter oilseed rape (Brassica napus ssp. oleifera) and winter turnip rape cultivars was determined. The virus transmission rate, expressed as the proportion of virus-infected plants which germinated from the seed was for the oilseed rape cvs Jet Neuf 0.1%, Solida 0.4%, Silesia 0.8%, Darmor 1.2%, SL-507 0.2%, SL-509 0.0% and for the winter turnip rape cv. Perko 1.5%. ELISA cannot be used in direct tests on bulk seed lots to estimate proportion of infected seed, but must be used on germinated seedlings.     

Aspects of hadrosaurian cranial anatomy

Supraorbital bones in Saurolophus angustirostris are described, and their presence in all hadrosaurs is suggested. Frontal-nasal and premaxillar-nasal fontanellae are distinguished in hadrosaurs; their presence is explained as connected with growth and considered to he responsible for the variability of crest structures. New data indicating the presence of a cartilaginous diverticulum nasi within the circumnarial depression in Saurobphus ongustirostris are presented. A physiological (respiratory and/or thermoregulatory) function of the nasal diverticulum is proposed.     

The binding of azide to human methemoglobin A0. Error analysis for the interpolative and noninterpolative methods.

The binding azide to human methemoglobin A0 has been studied at 6 degrees, pH 7, and I = 0.2 by three spectroscopic methods: (1) the conventional interpolative method, (2) an interpolative dialysis technique, and (3) a noninterpolative method. The interpolative methods assume that the fractional spectral change equals the fraction of heme sites bound by ligand, while the noninterpolative method measures the extent of binding directly, i.e., without the interpolative assumption. Both experiment and error analysis show that method 1 has low precision, and consequently, gives an inherently unreliable binding isotherm. Method 2 achieves high experimental and intrinsic precision. However, method 3, which also has high precision, clearly proves that the interpolative assumption of method 2 is incorrect. That is, the true fractional extent of binding becomes equal to the fractional spectral change only after about 97% of heme sites have been bound with ligands.     

European checkerspots (Melitaeini: Lepidoptera,Nymphalidae) are not aposematic – the point of view of great tits (Parus major)

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Multiplex panels of polymorphic microsatellite loci for two cryptic bat species of the genus Pipistrellus,developed by cross‐species amplification within the family Vespertilionidae

The paper presents multiplex panels of polymorphic microsatellites for two closely related cryptic species Pipistrellus pipistrellus and Pipistrellus pygmaeus. We tested the cross‐species amplification of 34 microsatellite loci, originally developed for five vespertilionid bat species. Ten and nine polymorphic loci in P. pipistrellus (mean number of alleles per locus = 10.5) and P. pygmaeus (8.1), respectively, in three multiplex polymerase chain reactions per species were amplified. All loci can be analysed in a single fragment analysis and can be used as markers to the study of evolution and the ecology of structured populations of socially living bats.