Soil micromycete diversity in the hypersaline Dead Sea coastal area,Israel

In the present study, a soil microfungal community was examined over a one-year period (1999–2000) at the western shore of the Dead Sea. A total of 78 species from 40 genera were isolated. The most prominent features of mycobiota of the territory studied were: (i) the prevailing number of melanin-containing micromycetes (46 species, 65.5 % of the total isolate number); (ii) a large share of teleomorphic Ascomyceta (26 species, 18.5 % of isolates); (iii) combination of true soil and plant surface inhabiting species; (iv) spatial and temporal variation of the mycobiota composition; (v) very low fungal density (nearly 500-fold lower than in the Judean Desert soil). These features are formed under the extremely stressful xeric and oligotrophic conditions in which the Dead Sea coastal micromycete community exists. Nine species (Alternaria alternata, A. raphani, Aspergillus niger, Aureobasidium pullulans, Chaetomium globosum, Ch. murorum, Cladosporium cladosporioides, Penicillium aurantiogriseum, and Stachybotrys chartarum) were considered a characteristic micromycete complex for the Dead Sea coastal habitat based on the spatial and temporal occurrence of these species. Many of the micromycetes isolated, including almost all the species listed above, are known to be distributed worldwide occurring in different soil types. This confirms the conclusion of many mycologists working in areas with saline and arid soils that there is no halo-and thermophilous mycobiota characteristic for those soils.     

cis and trans factors affecting Mos1 mariner evolution and transposition in vitro, and its potential for functional genomics

Mos1 and other mariner/Tc1 transposons move horizontally during evolution, and when transplanted into heterologous species can transpose in organisms ranging from prokaryotes to protozoans and vertebrates. To further develop the Drosophila Mos1 mariner system as a genetic tool and to probe mechanisms affecting the regulation of transposition activity, we developed an in vitro system for Mos1 transposition using purified transposase and selectable Mos1 derivatives. Transposition frequencies of nearly 10^–3/target DNA molecule were obtained, and insertions occurred at TA dinucleotides with little other sequence specificity. Mos1 elements containing only the 28 bp terminal inverted repeats were inactive in vitro, while elements containing a few additional internal bases were fully active, establishing the minimal cis-acting requirements for transposition. With increasing transposase the transposition frequency increased to a plateau value, in contrast to the predictions of the protein overexpression inhibition model and to that found recently with a reconstructed Himar1 transposase. This difference between the ‘natural’ Mos1 and ‘reconstructed’ Himar1 transposases suggests an evolutionary path for down-regulation of mariner transposition following its introduction into a naïve population. The establishment of the cis and trans requirements for optimal mariner transposition in vitro provides key data for the creation of vectors for in vitro mutagenesis, and will facilitate the development of in vivo systems for mariner transposition.     

Genome search in celiac disease.

Celiac disease (CD), a malabsorption disorder of the small intestine, results from ingestion of gluten. The HLA risk factors involved in CD are well known but do not explain the entire genetic susceptibility. To determine the localization of other genetic risk factors, a systematic screening of the genome has been undertaken. The typing information of 281 markers on 110 affected sib pairs and their parents was used to test linkage. Systematic linkage analysis was first performed on 39 pairs in which both sibs had a symptomatic form of CD. Replication of the regions of interest was then carried out on 71 pairs in which one sib had a symptomatic form and the other a silent form of CD. In addition to the HLA loci, our study suggests that a risk factor in 5qter is involved in both forms of CD (symptomatic and silent). Furthermore, a factor on 11qter possibly differentiates the two forms. In contrast, none of the regions recently published was confirmed by the present screening.     

Osteogenesis promoted by calcium phosphate N,N-dicarboxymethyl chitosan

The effects of N,N-dicarboxymethyl chitosan (DCMC) on the precipitation of insoluble calcium salts, namely phosphate, sulfate, oxalate, carbonate, bicarbonate and fluoride, and magnesium salts, namely phosphate and carbonate, were studied. Results indicated that the chelating ability of DCMC interfered effectively with the well-known physico-chemical behaviour of magnesium and calcium salts. Dicarboxymethyl chitosan formed self-sustaining gels upon mixing with calcium acetate, as a consequence of calcium chelation. DCMC mixed with calcium acetate and with disodium hydrogen phosphate in appropriate ratios (molar ratio Ca/DCMC close to 2.4) yielded a clear solution, from which, after dialysis and freeze-drying, an amorphous material was isolated containing an inorganic component about one half its weight. This compound was used for the treatment of bone lesions in experimental surgery and in dentistry. Bone tissue regeneration was promoted in sheep, leading to complete healing of otherwise non-healing surgical defects. Radiographic evidence of bone regeneration was observed in human patients undergoing apicectomies and avulsions. The DCMC–CaP chelate favoured osteogenesis while promoting bone mineralization.     

Elevated CO2 concentrations and stomatal density: observations from 17 plant species growing in a CO2 spring in central Italy

Stomatal density (SD) and stomatal conductance ( g _s) can be affected by an increase of atmospheric CO₂ concentration. This study was conducted on 17 species growing in a naturally enriched CO₂ spring and belonging to three plant communities. Stomatal conductance, stomatal density and stomatal index (SI) of plants from the spring, which were assumed to have been exposed for generations to elevated [CO₂], and of plants of the same species collected in a nearby control site, were compared. Stomatal conductance was significantly lower in most of the species collected in the CO₂ spring and this indicated that CO₂ effects on g _s are not of a transitory nature but persist in the long term and through plant generations. Such a decrease was, however, not associated with changes in the anatomy of leaves: SD was unaffected in the majority of species (the decrease was only significant in three out of the 17 species examined), and also SI values did not vary between the two sites with the exception of two species that showed increased SI in plants grown in the CO₂-enriched area. These results did not support the hypothesis that long-term exposure to elevated [CO₂] may cause adaptive modification in stomatal number and in their distribution.     

Enzymes from Sulfolobus shibatae for the production of trehalose and glucose from starch

Enzymes that convert starch and dextrins to α,α-trehalose and glucose were found in cell homogenates of the hyperthermophilic acidophilic archaeon Sulfolobus shibatae DMS 5389. Three enzymes were purified and characterized. The first, the S. shibatae trehalosyl dextrin-forming enzyme (SsTDFE), transformed starch and dextrins to the corresponding trehalosyl derivatives with an intramolecular transglycosylation process that converted the glucosidic linkage at the reducing end from α-1,4 to α-1,1. The second, the S. shibatae trehalose-forming enzyme (SsTFE), hydrolyzed the α-1,4 linkage adjacent to the α-1,1 bond of trehalosyl dextrins, forming trehalose and lower molecular weight dextrins. These two enzymes had molecular masses of 80 kDa and 65 kDa, respectively, and showed the highest activities at pH 4.5. The apparent optimal temperature for activity was 70°C for SsTDFE and 85°C for SsTFE. The third enzyme identified was an α-glycosidase (SsαGly), which catalyzed the hydrolysis of the α-1,4 glucosidic linkages in starch and dextrins, releasing glucose in a stepwise manner from the nonreducing end of the polysaccharide chain. The enzyme had a molecular mass of 313 kDa and showed the highest activity at pH 5.5 and at 85°C. Received: October 29, 1997 / Accepted: April 29, 1998     

Evidence of Field-Evolved Resistance of Spodoptera frugiperda to Bt Corn Expressing Cry1F in Brazil That Is Still Sensitive to Modified Bt Toxins

Brazil ranked second only to the United States in hectares planted to genetically modified crops in 2013. Recently corn producers in the Cerrado region reported that the control of Spodoptera frugiperda with Bt corn expressing Cry1Fa has decreased, forcing them to use chemicals to reduce the damage caused by this insect pest. A colony of S. frugiperda was established from individuals collected in 2013 from Cry1Fa corn plants (SfBt) in Brazil and shown to have at least more than ten-fold higher resistance levels compared with a susceptible colony (Sflab). Laboratory assays on corn leaves showed that in contrast to SfLab population, the SfBt larvae were able to survive by feeding on Cry1Fa corn leaves. The SfBt population was maintained without selection for eight generations and shown to maintain high levels of resistance to Cry1Fa toxin. SfBt showed higher cross-resistance to Cry1Aa than to Cry1Ab or Cry1Ac toxins. As previously reported, Cry1A toxins competed the binding of Cry1Fa to brush border membrane vesicles (BBMV) from SfLab insects, explaining cross-resistance to Cry1A toxins. In contrast Cry2A toxins did not compete Cry1Fa binding to SfLab-BBMV and no cross-resistance to Cry2A was observed, although Cry2A toxins show low toxicity to S. frugiperda. Bioassays with Cry1AbMod and Cry1AcMod show that they are highly active against both the SfLab and the SfBt populations. The bioassay data reported here show that insects collected from Cry1Fa corn in the Cerrado region were resistant to Cry1Fa suggesting that resistance contributed to field failures of Cry1Fa corn to control S. frugiperda.