N metabolism performance in Chenopodium quinoa subjected to drought or salt stress conditions.

Currently it is estimated that the 20% of total cultivated land is affected by salt. Besides, drought events will increase worldwide. These factors are affecting plant growth and crop production compromising food security. Within this context, quinoa (Chenopodium quinoa) is becoming an alternative pseudocereal for food supply due to its capacity to grow under harsh environmental conditions. Besides, it is being proposed as key model species to study the physiological processes that permit this tolerance, although how N metabolism responds has been barely studied. This paper addresses, on one hand, the response of quinoa's N metabolism (N uptake, translocation, reduction and assimilation) under the forthcoming climatic conditions and, on the other hand, the comparison of the effects of both stresses when plants have similar relative water content and photosynthetic rates. Under mild salt stress (120 and 240 mM NaCl) N assimilation is not affected, while the N uptake is favored. Under severe salt stress (500 mM NaCl), N uptake is reduced, decreasing leaf nitrate and protein concentration; nevertheless, leaf free amino acids are maintained -to perform osmotic adjustment-. N uptake rate is more affected under drought than under severe salt; furthermore, under severe salt stress, quinoa allocates more nitrogen to roots to finely regulate NO3- and Cl- uptake, while under drought it allocates more to leaves to ensure photosynthesis. These results indicate that quinoa's N metabolism is tolerant to drought and salt stress, although the strategies of this species for coping with the aforementioned stresses are different.

The type of competition modulates the ecophysiological response of grassland species to elevated CO2 and drought.

The effects of elevated CO2 and drought on ecophysiological parameters in grassland species have been examined, but few studies have investigated the effect of competition on those parameters under climate change conditions. The objective of this study was to determine the effect of elevated CO2 and drought on the response of plant water relations, gas exchange, chlorophyll a fluorescence and aboveground biomass in four grassland species, as well as to assess whether the type of competition modulates that response. Elevated CO2 in well-watered conditions increased aboveground biomass by augmenting CO2 assimilation. Drought reduced biomass by reducing CO2 assimilation rate via stomatal limitation and, when drought was more severe, also non-stomatal limitation. When plants were grown under the combined conditions of elevated CO2 and drought, drought limitation observed under ambient CO2 was reduced, permitting higher CO2 assimilation and consequently reducing the observed decrease in aboveground biomass. The response to climate change was species-specific and dependent on the type of competition. Thus, the response to elevated CO2 in well-watered grasses was higher in monoculture than in mixture, while it was higher in mixture compared to monoculture for forbs. On the other hand, forbs were more affected than grasses by drought in monoculture, while in mixture the negative effect of drought was higher in grasses than in forbs, due to a lower capacity to acquire water and mineral nutrients. These differences in species-level growth responses to CO2 and drought may lead to changes in the composition and biodiversity of the grassland plant community in future climate conditions.

Genome sequence of enterohaemorrhagic Escherichia coli O157:H7.

The bacterium Escherichia coli O157:H7 is a worldwide threat to public health and has been implicated in many outbreaks of haemorrhagic colitis, some of which included fatalities caused by haemolytic uraemic syndrome. Close to 75,000 cases of O157:H7 infection are now estimated to occur annually in the United States. The severity of disease, the lack of effective treatment and the potential for large-scale outbreaks from contaminated food supplies have propelled intensive research on the pathogenesis and detection of E. coli O157:H7 (ref. 4). Here we have sequenced the genome of E. coli O157:H7 to identify candidate genes responsible for pathogenesis, to develop better methods of strain detection and to advance our understanding of the evolution of E. coli, through comparison with the genome of the non-pathogenic laboratory strain E. coli K-12 (ref. 5). We find that lateral gene transfer is far more extensive than previously anticipated. In fact, 1,387 new genes encoded in strain-specific clusters of diverse sizes were found in O157:H7. These include candidate virulence factors, alternative metabolic capacities, several prophages and other new functions--all of which could be targets for surveillance.

Sol-gel trapping of functional intermediates of hemoglobin: geminate and bimolecular recombination studies.

The encapsulation of proteins in porous sol-gels is a promising technique for generating, trapping, and probing functionally significant nonequilibrium protein species. An essential step needed in the pursuit of that goal is establishing the degree to which the sol-gel limits conformational change upon adding or removing substrates. In the present study, geminate recombination and solvent phase bimolecular recombination of CO to human adult hemoglobin (HbA) are used as sensitive probes of the degree of conformational constraint within the sol-gel. Two forms of CO saturated encapsulated HbA are generated. In one case, designated [COHbA], the equilibrium form of COHbA is directly encapsulated. In the second case, designated as [deoxyHbA] + CO, the equilibrium form of deoxyHbA is encapsulated and only after the sample has aged is CO introduced to the HbA through the porous sol-gel matrix. Three different preparative protocols are used to generate the sol-gels for each of the two forms of encapsulated COHbA. The kinetic traces obtained from these encapsulated samples allow for an easy evaluation of the extent to which the sol-gel is locking in the initial tertiary/quaternary structure. The results show that the sol-gel encapsulated samples can be used with pulsed laser sources and that one of the tested encapsulation protocols is far superior with respect to conformational locking. This protocol is used to trap and probe nonequilibrium forms such as the liganded T state of HbA, a species whose properties are needed to fully explore allostery in HbA.

A shotgun optical map of the entire Plasmodium falciparum genome.

The unicellular parasite Plasmodium falciparum is the cause of human malaria, resulting in 1.7-2.5 million deaths each year. To develop new means to treat or prevent malaria, the Malaria Genome Consortium was formed to sequence and annotate the entire 24.6-Mb genome. The plan, already underway, is to sequence libraries created from chromosomal DNA separated by pulsed-field gel electrophoresis (PFGE). The AT-rich genome of P. falciparum presents problems in terms of reliable library construction and the relative paucity of dense physical markers or extensive genetic resources. To deal with these problems, we reasoned that a high-resolution, ordered restriction map covering the entire genome could serve as a scaffold for the alignment and verification of sequence contigs developed by members of the consortium. Thus optical mapping was advanced to use simply extracted, unfractionated genomic DNA as its principal substrate. Ordered restriction maps (BamHI and NheI) derived from single molecules were assembled into 14 deep contigs corresponding to the molecular karyotype determined by PFGE (ref. 3).

Presence of antibodies reacting with porcine circovirus in sera of humans, mice, and cattle.

Antibodies reacting with porcine circovirus (PCV) were found in sera of humans, mice, and cattle by means of an indirect immunofluorescence assay (IFA) and an ELISA. In man, the highest seroprevalence (23.9% in IFA and 30.2% in ELISA) was found among hospitalized patients with fever of partially unclear etiology. Non-hospitalized "healthy" persons of the former German Democratic Republic showed a significantly higher number of positive sera (IFA = 20%) than blood donors from Berlin-West (IFA = 8.6%). Murine sera reacted positive with PCV in IFA between 12 to 69% in different breeding groups and about 35% of cattle sera were found reactive with PCV in IFA. Double-staining IFAs, immuno-electron microscopy and immunoblotting showed that non-porcine antibodies reacted with PCV structural antigen. Mathematical analysis revealed that in ELISA, non-porcine antibodies reacted specifically with PCV. Loss of binding specificity of non-porcine antibodies in ELISA after storage of sera and lower maximal optical densities obtained at equal titers in ELISA with non-porcine than with porcine sera suggest that antibodies in man, mice and cattle are caused by related species specific viruses sharing antigenic epitopes with PCV.

[Demonstration of HBs antigen with the hepanostika test, an enzyme immunoassay (author's transl)]. / Der Nachweis von HBs-Antigen mit dem Hepanostika-test, einem Enzymimmunoassay.

Sensitivity, specificity and practicability of the Hepanostika test, a newly developed enzyme immunoassay by organon Teknika for the demonstration of HBs-antigen, was compared with results of the Aursria II 125 test. Smallest demonstrable concentration of the antigen in the Hepanostika test eas 3.125 ng/ml with antigens of subgroup ad and 2.08 ng/ml in those of subgroup ay, while it was 1.04 ng/ml for both subgroups with the Austria test. Among 2930 blood donors 85 antigen carriers were discovered by both tests, while with the Hepanostison test, a passive haemagglutination test from Oranon, only nine were discovered. In serial blood samples of patients with various disease there was only a slight difference between the two tests. The Hepanostika test had 1.6--3.88% nonspecific reactions, compared with 0.5-0.8% with the Ausria II 125 test. Both tests thus gave much more specific results than passive haemagglutination. The Hepanostika test is thus a satisfactory alternative to the Ausria test. Because of its high sensitivity it can be recommended for the diagnosis of HBs antigen among blood donors and in clinical laboratories.

[Demonstration of hepatitis-B(surface) antigen with the Hepatest: a new passive haemagglutination test (author's transl)]. / Der Nachweis von Hepatitis-B(Surface)-Antigen mit dem Hepatest. Ein neuer passiver Hämagglutinationstest

The Hepatest, a passive haemagglutination test, proved to be, like other tests of this group, significantly more sensitive for routine examination of hepatitis B(surface) antigen than tests of the first and second generation, but was not as sensitive as the Ausria II 125 test. The lowest HBs antigen concentration demonstrable in the Hepatest was 31 ng/ml for the subtype ad and 47 ng/ml for subtype ay (in the Ausria II 125 test lowest concentrations were 1.0 and 1.5 ng/ml, respectively). There were several false-positive reactions in the specificity test. Thus all positive reactions would need to be checked, more often than with the Ausria test. But the Hepatest proved to be the most practicable of all the third generation tests, both with regard to shortness of reaction time, technical requirements and ease of reading off the results.

Antigenic subgroups of hepatitis B (surface) antigen in Berlin (West) and their epidemiological aspects.

Sera of 334 hepatitis B patients and 118 sera of HBsAg carriers were tested for the distribution of the subgroups ad and ay by means of rheophoresis technique or solid phase radiommunoassay. The distribution of subgroups revealed a typical pattern. The ad-antigen determinant was more frequent in hepatitis B patients, blood donors and hemodialysis patients whereas the ay determinant was detected in drug users, guest workers and juveniles at a considerably higher percentage. The difference in distribution is discussed as an epidemiological phenomenon of hepatitis B virus, dependent on environmental factors characteristic for certain groups of the population. The routine testing for HGsAg subgroups is recommended as a valuable epidemiologic tool.

[Antibodies against hepatitis B (surface) antigen in patients with hepatitis and other groups of epidemiologic interest (author's transl)]. / Antikörper gegen Hepatitis B (surface)-Antigen bei Hepatitispatienten und anderen epidemiologisch interessanten Bevölkerungsgruppen

Sera of patients with hepatitis A and B and of patients in a hemodialysis unit as well as sera of drug addicts were examined for the presence of antibodies against hepatitis B (surface) antigen (HBsAg) employing the Ausab test - a new radioimmunoassay. In 79.3% of the hepatitis B patients the occurrence of antibodies against HBsAg (anti-HBsAg) was noted after the HBsAg had disappeared. In hepatitis A patients anti-HBsAg could be detected in 15.5% (adults) and in 4.6% (children) respectively. These antibodies persisted over an observation period up to 15 months and were not connected with the apparent illness at the time of the examination. These results are rather an indication of the frequency of antibodies against HBsAg in the normal population. In two patients with hepatitis A a delayed antibody reaction similar to that seen in hepatitis B patients was observed though HBsAg could not be detected (Ausria 125 test). It is assumed that these patients suffered from hepatitis B which on the basis of the negative HBsAg status was diagnosed as hepatitis A. According to that observation not all cases of HBsAg negative hepatitis are necessarily of type A but occasionally of type B not detectable by means of HBsAg assay at that time. Drug addicts without hepatitis at the time of investigation showed 50.8% anti-HBsAg, in 24.3% HBsAg was detected by means of the Ausria 125 test. In 19 drug addicts with positive antigen or antibody status a history of hepatitis was established. Patients of the hemodialysis unit were found to be HBsAg carriers in 9.2% and anti-HBsAg carriers in 53.5%. The data obtained from drug addicts and dialysis patients point to a high risk of infection in both groups and to a frequent contact with HBsAg (booster) in dialysis units. The combined application of sensitive tests for the detection of antigen and antibodies (radioimmunoassays) with regard to epidemiological and anamnestic studies is recomended.

Lymphoproliferative disease in a cotton-top marmoset after inoculation with infectious mononucleosis-derived Epstein-Barr virus.

Injection of concentrated EBV derived from cells of the Kaplan line of infectious mononucleosis (IM) origin resulted in malignant lymphoproliferation in one out of three cotton-top marmosets 6 weeks after inoculation. Two additional animals receiving the same isolate after incubation with an antibody-containing human serum did not develop tumors. Inoculation of concentrated virus derived from the P3HR-1 line of Burkitt origin did not lead to lymphoproliferations in five marmosets. Three of these received non-neutralized, and two received neutralized P3HR-1 virus. The tumor obtained with the Kaplan isolate revealed characteristics of a lymphosarcome. It contained EBV-specific DNA. In addition, EBV-synthesizing lymphoblastoid lines were established from a tumorous lymph-node, as well as from the spleen of the diseased marmoset. Virus recovered from these lines transformed lymphocytes derived from spleens of healthy marmosets. The tumor-bearing animal developed low levels of anti-VCA antibodies during the course of tumor growth. These data demonstrate the oncogenic potential of EBV directly derived from cells of IM origin.

[Demonstration of hepatitis B (surface) antigen. A comparison of different serological methods (author's transl)]. / Der Nachweis von Hepatitis-B-(surface)-Antigen. Ein Vergleich verschiedener serologischer Verfahren

Four third generation tests for the demonstration of hepatitis B (surface) antigen were assessed (Hepamosticon test from Organon-Teknika, Auscell test, Ausria I 125 test and Ausria II 125 test from Abbott) and the results compared with those of immunodiffusion and counter-current electrophoresis (1st and 2nd generation). The results show that the Ausria II 125 test comes very close to the ideal of an optimal test for demonstrating hepatitis B (surface) antigen (HBs antigen). It is clearly superior to both other tests from Abbott and in particular to the Hepanosticon test and the tests of the 1st and 2nd generation. The Ausria I 125 test can be considered as a precursor of the Ausria II 125 test and is less satisfactory as regards sensitivity and practicability and approximately equally good as regards specificity. It should not be considered in the choice of a sensitive test for demonstrating HBs antigen as it has been replaced by the Ausria II 125 test. The Auscell test resembles the Ausria I 125 test as regards sensitivity, its specificity is considerably lower. There are also definite disadvantages in the practicability. The Hepanosticon test is considerably less sensitive than the three tests from Abbott while it is easy to carry out. Its specificity is worse than that of radio-immunoassay and better than that of the Auscell test. In any case it is necessary to test the specificity in all passive haemagglutination tests. Due to poor sensitivity use of both tests of 1st and 2nd generations must be discouraged.

Demonstration of infectivity in marmosets experimentally infected with hepatitis A.

Experimental infection of marmosets with marmoset serum (Berlin strain) suggests that the liver is not necessarily the primary site of virus replication since infectivity is found in blood long before the clinical onset of hepatitis.