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PubMed1977

Life history and host specificity of Mediorhynchus centurorum Nickol 1969 (Acanthocephala: Gigantorhynchidae).

Examination of 1905 arthropods from a swamp and surrounding pasture in sothern Louisiana revealed larval specimens of Mediorhynchus centurorum in 8 of 228 woodroaches, Parcoblatta pensylvanica, but in no other species. The life cycle was confirmed by feeding eggs of M. centurorum to laboratory-reared woodroaches. Cystacanths later recovered from the woodroaches developed into mature worms when pipetted into esophaguses of red-bellied woodpeckers, Centurus carolinius: red-headed woodpeckers, Melanerpes erythrocephalus; yellow-shafted flickers, Colaptes auratus; and a hairy woodpecker, Dendrocopos villosus. Infection was achieved in all woodpeckers fed cystacanths at least 47 days old and the mean prepatent period was 35 days. Cystacanths fed starlings, Sturnus vaulgaris, and red-winged blackbirds, Agelaius phoeniceus, did not produce infections although cystacanths from the same pool were infective to control woodpeckers. Larval development of Mediorhynchus centurorum in woodroaches did not differ significantly from that of M. grandis in grasshoppers. M. centurorum is the only species of the Gigantorhynchidae for which the life cycle has been confirmed by laboratory infections using an intermediate host species known infected nature.

Acanthocephala↗
PubMed1978

Ecology of Staphylococcus aureus: comparative characterization of strains isolated from man, cattle and sheep in Bulgaria and in the GDR.

Staphylococcus aureus strains from man, cattle and sheep have been differentiated by biochemical tests and by phage typing. Strains from pathological material of human origin mostly belong to the host-specific variety hominis, strains from mastitis in cattle mostly belong to the host-specific variety bovis. However, there are also strains from cattle which cannot be allotted to one of the known host-specific varieties and also strains which belong to the host-specific variety hominis. Strains from mastitis in sheep clearly differ from strains of human and bovine origin; these strains are designated as variety ovis. The frequency distribution of the host-specific varieties in man, cattle and sheep is the same in Bulgaria and in the GDR.

Animals↗
PubMed1979

The nature of arginine auxotrophy in cutaneous populations of staphylococci.

L-Arginine was required for growth by a high percentage of strains of Staphylococcus species that were niche-specific and/or host-specific, but was usually not required for growth by species showing a wide host range. Growth stimulation patterns with arginine intermediates indicated that most of the auxotrophic strains had blocks in an early step(s) in arginine biosynthesis. These strains were designated phenotypically as Arg(CHG) according to the Salmonella typhimurium classification scheme. Staphylococcus simulans strains appeared to be either ArgA or Arg I. The ArgI strains of S. simulans and S. capitis had moderate to high ornithine carbamoyltransferase (EC 2.1.3.3) activities and therefore could not be designated as argI mutants. ArgI strains in other species had no or very low ornithine carbamoyltransferase activities. All of the natural Staphylococcus auxotrophs tested grew in the presence of L-citrulline and had moderate to high argininosuccinase (EC 4.3.2.1) activities. Arginine auxotrophs of species with a wide host range were often capable of reverting to arginine-independent or complete prototrophic growth, whereas auxotrophs of species that tended to be niche-specific and/or host-specific were incapable of reversion to arginine-independence, even in the presence of various mutagens. A relationship between the nature of arginine auxotrophy and habitat is suggested.

Arginine↗
PubMed1978

[The mutual transmission of Staphylococcus aureus between humans and cattle and the environmental adaptation of hemolysin and fibrinolysin formation].

In an ecological investigation in 20 dairy herds of cattle we compared the characteristics of strains isolated from nasal swabs of milkers, from the udder of cows and from cases of mastitis in cows. In 7 herds we found definite strains in the nasal flora of the milkers and in the udder-flora of the cows which only differ in the formation of hemolysin and of fibrinolysin. In the other checked characteristics strains from man and strains from cattle show identical patterns. In 5 herds these strains correspond to the host-specific variety hominis, in 2 herds to the hostspecific--variety bovis. These results refer to an environmental adaptation of the phenotypically detectable formation of hemolysins and fibrinolysin. From the ecological point of view an exchange of strains between man and cattle is likely. The origin of strains which can not be alloted to one ot the known host-specific varieties can be explained by an environmental adaptation. Besides the facts that strains of the host-specific variety bovis occur only very rarely in man and that strains of the host-specific variety hominis occur occasionally in cattle the clinical significance of the reported results has to be clarified by further investigations.

Adaptation, Biological↗
PubMed1978

The peculiar behaviour of coliphage P1vir mutants on restricting hosts.

The sensitivity of two vir coliphage P1 mutants, to the host-specificity systems A, K, RII, and B of Escherichia coli, and to the newly identified host-specificity systems Mir and 59 of Klebsiella pneumoniae has been studied. Both 1 vir phages were completely resistant to the E. coli K, but were restricted 10(-5) by the B, mir and 59 systems. The P1 parent, on the contrary, was restricted 10(-2) by all of the above mentioned hosts. The possible role of phage coded proteins in the altered sensitivity of the vir strains has been studied by analysing the sensitivity of both P1, and P1vir to the various systems in the presence of chloramphenicol. Protein synthesis inhibition by chloramphenicol did not significantly influence the sensitivity of P1 and P1vir to various restricting hosts. It is concluded that the altered sensitivity of vir mutants depends on the different affinities of the mutated phage DNA sequence for the enzymes of the various restriction and modification systems. The possibility that the phage repressor contributes to the regulation of the restriction and modification enzymes is also discussed.

Chloramphenicol↗
PubMed1978

[Macrolid resistance in Staphylococcus aureus strains from chicken synovitis and dermatitis in industrial production].

In outbreaks of synovitis and dermatitis in chicken caused by Staphylococcus (Staph.) aureus we observed erythromycin-resistant strains. These strains belong to the host-specific variety gallinae of Staph. aureus or can not be alloted to one of the known host-specific varieties. The macrolide-resistance-determinant is not carried by a plasmid, presumably it is located on the chromosome. The strains show constitutively cross-resistance to erythromycin, thurimycin, linomycinc and pristinamycin (M-L-S-phenotype). An ecological investigation in a chicken farm has shown that there is no distribution of Staph. aureus-strains from chicken to workers and no occurence of macrolide-resistance in Staph. aureus-strains from the workers.

Animals↗
PubMed2026

Species-specific structuring of gut bacterial and fungal communities in honey bees Apis cerana and Apis mellifera.

Honey bee gut microbiome studies have primarily emphasized bacteria, leaving fungal communities comparatively overlooked despite their ecological and functional importance. Whole-genome shotgun metagenomics of Apis cerana and Apis mellifera revealed fungal assemblages dominated by Ascomycota, with Basidiomycota and Microsporidia in minor proportions, alongside gut bacterial communities composed mainly of Pseudomonadota, Bacillota, and Actinomycetota. The bacterial diversity was markedly higher in A. mellifera (Shannon = 5.90; Simpson = 0.98) than in A. cerana (Shannon = 4.01; Simpson = 0.94; p > 0.05), while fungal diversity remained comparable between species (p > 0.05). Beta-diversity analyses revealed strong host-specific clustering for both bacterial (PERMANOVA R2 = 0.7989, p > 0.05) and fungal communities (R2 = 0.7218, p > 0.05), indicating distinct microbial organization driven by host species. Bacterial-fungal co-occurrence patterns exhibited host-specific structuring, suggesting differential inter-kingdom community organization between A. cerana and A. mellifera. Linear Discriminant Analysis Effect Size (LEfSe) identified 93 discriminatory fungal taxa (45 enriched in A. cerana, 48 in A. mellifera), highlighting yeast-dominated signatures in A. mellifera and Basidiomycota-affiliated enrichments in A. cerana. KEGG and CAZy profiling revealed host- and kingdom-specific functional differences, with bacterial communities of A. mellifera showing distinct representation of carbohydrate metabolism and nutrient-cycling functions, while fungal communities exhibited a comparatively narrower functional repertoire. Together, these findings provide a high-resolution view of honey bee bacterial and fungal microbiomes, highlighting strong host-driven divergence in taxonomy, function, and cross-kingdom interactions.

Animals↗
PubMed1976

Two restriction and modification systems in Staphylococcus aureus NCTC8325.

The presence of two distinct host specificities in Staphylococcus aureus strain NCTC8325 was revealed by the isolation of restriction- and modification-deficient mutants. The two host specificity systems, designated S1 and S2, are both active on phage 80mualpha but are not additive in their restricting activity. Restriction-deficient, modification-proficient mutants were invariably affected in both restriction systems. The functional relationship between these two systems is discussed.

DNA, Bacterial↗