Genetic differences between two strains of Xylella fastidiosa revealed by suppression subtractive hybridization

Suppression subtractive hybridization was used to rapidly identify 18 gene differences between a citrus variegated chlorosis (CVC) strain and a Pierce's disease of grape (PD) strain of Xylella fastidiosa. The results were validated as being highly representative of actual differences by comparison of the completely sequenced genome of a CVC strain with that of a PD strain.     

Genetic differences between two sympatric morphs of Arctic charr confirmed by microsatellite DNA

Significant genetic differences ( F _ST = 0·032) were found between littoral and profundal morphs of Arctic charr Salvelinus alpinus from Fjellfrøsvatn, northern Norway, using microsatellite DNA analysis. The morphs had strong reproductive isolation in time and space; the segregation of a separate profundal morph is rare in postglacial lakes.     

Comparison of two Egyptian strains of Schistosoma mansoni in hamsters

In human infection with Schistosoma mansoni from Beni-Suef, the eggs were encountered more frequently in the urine of patients than in infection with S. mansoni from Giza, where eggs were passed into the stool. A comparative study of the two strains of S. mansoni from Beni-Suef and Giza has been carried out in golden hamster. Consistent strain differences were observed. The Beni-Suef strain proved to have lower worm recovery and different egg distribution patterns in tissues of infected hamsters. Worms of both sexes of this strain were larger in size and required a longer period to reach maturity. Hence, the prepatent period was prolonged. Significant differences between the two strains were also noted in the number of eggs per worm. A lower mortality rate and a longer survival time were encountered in hamsters infected with the Beni-Suef strain.     

Serum chemistry reference values in two strains of Syrian hamsters

Blood samples were collected from 30 male and female hamsters (Mesocricetus auratus) from two sources. Serum was collected and analyzed for 17 biochemical values. The results were analyzed statistically and comparisons were made between males and females and between strains.     

Major differences between the rrnA operons of two strains of Agrobacterium vitis

The sequence of the rrnA operon and its flanking regions was determined for the Agrobacterium vitis type strain NCPPB3554. Compared to the earlier obtained rrnA sequence of A. vitis strain S4, several important differences were noted: the sequences diverged at the 5′-flanking region, within the 16S–23S intergenic region, and within the 23S rRNA sequence. The B8 stem-loop structure at the 5′-end of the 23S rRNA of strain NCPPB3554 was 142 nt shorter than that of strain S4. These findings have important consequences for the use of ribosomal RNA gene sequences in phylogenetic comparisons. Received: 16 February 1996 / Accepted: 26 April 1996     

Novel differences between two human prion strains revealed by two-dimensional gel electrophoresis

The phenotype of human sporadic prion diseases is affected by patient genotype at codon 129 of the prion protein (PrP) gene, the site of a common methionine/valine polymorphism, and by the type of the scrapie PrP (PrP(Sc)), which likely reflects the prion strain. However, two distinct disease phenotypes, identified as sporadic Creutzfeldt-Jakob disease (M/M2 sCJD) and sporadic fatal insomnia (sFI), share methionine homozygosity at codon 129 and PrP(Sc) type 2. One-dimensional gel electrophoresis and immunoblotting reveal no difference between the M/M2 sCJD and sFI species of PrP(Sc) in gel mobility and glycoform ratio. In contrast, the two-dimensional immunoblot demonstrates that in M/M2 sCJD the full-length PrP(Sc) form is overrepresented and carries glycans that are different from those present in the PrP(Sc) of sFI. Because the altered glycans are detectable only in the PrP(Sc) and not in the normal or cellular PrP (PrP(C)), they are likely to result from preferential conversion to PrP(Sc) of rare PrP(C) glycoforms. This is the first evidence that a qualitative difference in glycans contributes to prion diversity.     

Genetic differences between Escherichia coli O26 strains isolated in Brazil and in other countries

Genomic diversity among 34 strains of Escherichia coli belonging to different serotypes of the O26 serogroup -- encompassing strains from different geographical origins and Shiga toxin-negative Brazilian strains -- was evaluated through random amplified polymorphic DNA (RAPD) analysis. Our results indicate that Brazilian and non-Brazilian O26 strains fall under distinct but closely related differentiation clusters. RFLP-PCR analysis of the fliC gene sequence was done in order to identify the H(-) serotypes and served to confirm the clustering pattern obtained in the dendrogram generated from RAPD data. The epidemiological significance of these data is discussed.     

Significant differences between the chloroplast genomes of two Acetabularia mediterranea strains

Summary The chloroplast DNAs of Acetabularia mediterranea strains 5 and 17 differ significantly in their restriction patterns. Southern blotting analysis using gene probes derived from the coding regions of spinach genes showed that psbB and petB each map to unique restriction fragments which are shared in strains 5 and 17. On the other hand psaA, psbA and rbcL map to different restriction fragments in strains 5 and 17 probably as a result of restriction fragment length polymorphism. In addition to restriction fragment polymorphism there is evidence for much larger differences in the organization of the plastome. The most striking difference is the absence in strain 5 of a 10 kb repeated sequence which has previously been demonstrated in strain 17. However, both strains apparently share at least 8 kb of the 10 kb repeated sequence. Restriction analysis of independent clones of the 10 kb sequence revealed a family of non-identical repeats.This paper is dedicated to the memory of Prof. H.G. Schweiger, Director of the Max-Planck-Institut fur Zellbiologie, who died in November 1986Deceased     

Genetic control ofHylemya antiqua III. Differences in pupation ability between two strains

Some relevant traits of a wild (L) and a laboratory (C) strain of Hylemya antiqua (Meigen ), determining differences in their pupation ability under experimental conditions have been investigated in relation to genetic control. The wild strain showed an intrinsic higher pupation ability than the laboratory strain. The minimum feeding period was 0.6 days longer for the C strain. The minimum larval dry weight was different for the two strains. With a normal feeding period C larvae pupated on average 1.63 days later than L larvae. By the shortening of the larval feeding period an acceleration of the larval development of both strains was observed: the acceleration of development was more marked for the wild strain. This result has been contrasted with published works on Drosphila. The consequences of these differences as far as the competitive ability of each strain is concerned, have been discussed in relation to genetic control.     

Genetic differences in the levator ani muscle weight between inbred and congenic mouse strains.

Significant differences in relative weight of the levator ani muscle (LAW) between inbred and congenic mouse strains, differing genetically only by the major histocompatibility H-2 complex were found. It is assumed that a genetic factor (Hom-1), identical or closely associated wi th the H-2 complex, is one of the genes which influence LAW. These experiments suggest that for assay methods for myotropic activity of androgens groups of animals may be used with a homogenous genotype.     

Genetic analysis of biochemical differences of Yersinia pestis strains

Literature data and results of our experimental studies on genetic base of biochemical differentiation of Yersinia pestis strains of various subspecies and biovars are summarized in the review. Data on variability of genes coding biochemical features (sugar and alcohol fermentation, nitrate reduction), the differential development of which are the base of existing phenotypic schemes of Y. pestis strains classification, are presented. Variability of these genes was shown to have possible use for the development of genetic classification of Y. pestis strains of various subspecies and biovars.     

Transformation of Salmonella typhimurium with plasmid DNA: differences between rough and smooth strains.

Lipopolysaccharide-defective mutants of Salmonella typhimurium were transformed by plasmid DNA with a Ca2+ treatment method. Only those mutants with an Rc or Rd2 chemotype, due to galE or rfaF mutations, respectively, gave efficiencies greater than 10(5) transformants per microgram of DNA, frequencies 8- to 630-fold higher than with smooth strains or other rough mutants.