Self-demise of soft rot bacteria by activation of microbial predators by pectin-based carriers

Soft rot pectobacteria (SRP) are phytopathogens of the genera Pectobacterium and Dickeya that cause soft rots on a wide range of crops and ornamental plants. SRP produce plant cell wall degrading enzymes (PCWDEs), including pectinases. Bdellovibrio and like organisms are bacterial predators that can prey on a variety of Gram-negative species, including SRP. In this research, a low methoxyl pectin (LMP)-based immobilization system for B. bacteriovorus is established. It takes advantage that pectin residues induce PCWDE secretion by the pathogens, bringing upon the release of the encapsulated predators. Three commercial LMPs differing in the degree of esterification (DE) and amidation (DA) were tested as potential carriers, by examining their effect on SRP growth, enzymes secretion and substrate breakdown. A clear advantage was observed for pectin 5 CS with the lowest DE and DA content. The degradation of 5 CS pectin-based carriers was further optimized by reducing cross-linker and pectin concentration, by adding gelatin and by dehydration. This resulted in SRP-induced disintegration of the carrier within 72 h. The released encapsulated predator caused a large decrease in SRP population while its own significantly increased, demonstrating the efficiency of this system in which the pathogen brings about its own demise.     

Widespread amplification of amplified fragment length polymorphisms (AFLPs) in marine Antarctic animals

Although recent years have witnessed a rapid growth in the number of genetic studies of Antarctic organisms, relatively few studies have so far used nuclear markers, possibly due to the perceived cost and difficulty of isolating markers such as microsatellites. However, an often overlooked alternative is to use amplified fragment length polymorphisms (AFLPs), a versatile and low-cost method capable of generating large numbers of predominantly nuclear loci in virtually any organism. We conducted a literature review of population genetic studies of Antarctic organisms, finding that fewer than 10% used AFLPs. Moreover, a strong taxonomic bias was found, with studies employing mitochondrial DNA or microsatellites focussing predominantly on animals, while those using AFLPs were mostly of plants or lower organisms. Consequently, we explored the extent to which AFLPs amplify across a range of Antarctic marine animal taxa by genotyping eight individuals each of twelve different species, ranging from echinoderms through soft corals to pelagic fish, at four selective primer combinations. AFLPs readily amplified across all of the taxa, generating between 32 and 84 loci per species, with on average 56.5% of these being polymorphic. In general, levels of polymorphism bore little relationship with expectations based on larger populations of broadcast-spawning species being more variable, though we did find a tentative positive correlation between the number of AFLP bands amplified and a measure of effective population size. Our study lends further support for the utility and ease of use of AFLPs and their suitability for studies of Antarctic species across a wide range of taxa.     

Helicobacter pylori and Peptic Ulcer Disease Therapies: A Survey of Gastroenterologists in Israel

Background. Eradication of Helicobacter pylori has become a therapeutic option in the treatment of patients with peptic ulcer disease. The aim of this study was to evaluate the current management strategies of Israeli gastroenterologists in the diagnosis and treatment of H. pylori- related peptic ulcer disease, 14 years after the discovery of H. pylori.
Materials and Methods. A questionnaire was mailed to all specialists in gastroenterology, members of the Israel Gastroenterological Association (IGA). Replies were received from 60% of Israel Board-certified gastroenterology specialists.
Results. Over 89% of the gastroenterologists (89.1%) noted that they recommend anti- H. pylori treatment. 94.5% said that they treat duodenal ulcer in the first presentation with anti- H. pylori medication and 75% said that they do so in cases of recurrent duodenal ulcer. According to the replies received, there is a strong consensus towards triple treatment as the favored anti -H. pylori treatment; no one noted the use of dual treatment. Seven-day triple treatment was prescribed by 83.6% of the gastroenterologists who responded. Of these, the great majority, 89.1%, stated that they use proton pump inhibitors (PPI) in combination with any two of the following antibiotics: metronidazole (47.3%), tinidazole (29.1%), clarithromycin (61.8%), and amoxicillin (40%).
Conclusion. At the time of the survey, most Israel Board-certified gastroenterology specialists prescribed triple anti- H. pylori treatment of one-week's duration.     

Heterogeneous distribution of SNPs in the human genome: Microsatellites as predictors of nucleotide diversity and divergence

Understanding the forces that govern the distribution of single nucleotide polymorphisms is vital for many of their applications. Here we conducted a systematic search to quantify how both SNP density and human–chimpanzee divergence vary around different repetitive sequences. We uncovered a highly complicated picture in which these quantities often differ significantly from the genome-wide average in regions extending more than 20 kb, the direction of the deviation varying with repeat number and motif. AT microsatellites in particular are potent predictors of SNP density, long (AT)_n repeat tracts tending to be found in regions of significantly reduced SNP density and low GC content. Although the causal relationships remain difficult to determine, our results indicate a strong relationship between microsatellites and the DNA that flanks them. Our results help to explain the mixed picture that emerges from other studies and have important implications for the way in which genetic diversity is distributed in our genomes.     

The demonstration of acid phosphatase in cultured 3T3 mouse cells.

Acid phosphatase has been demonstrated ultrastructurally in 3T3 and SV40-3T3 mouse cells using sodium beta-glycerophosphate and p-nitrophenyl phosphate as substrate. The former substrate only demonstrates the enzyme in lysosomes and elements of the Golgi apparatus while the latter demonstrates it in the cisternae of the endoplasmic reticulum and in the cell surface as well as at lysosomal sites. The significance of surface acid phosphatase activity is discussed in terms of sublethal autolysis.