Race specific resistance against Phytophthora infestans in potato is controlled by more genetic factors than only R-genes

Summary For RFLP mapping of R-genes, determining resistance to specific races of Phytophthora infestans in tetraploid potato, it is necessary to develop well segregating populations at the 2x level. During mapping studies, evidence was obtained that more genetic factor(s) are involved in the expression of R-genes than conventionally believed. Two experiments are described in which such an additional genetic factor was suppressing or enhancing the expression of unknown R _nand R _ifactors. R _nand R _iappeared to be present in the investigated plant material, containing R4 and R10, or in one of the susceptible crossing parents. In a third experiment, the expression and the segregation of the well known R1 gene was influenced by an additional genetic factor. In that case there were indications for a dominant suppressor. This was established by the selection of susceptible plants carrying a RFLP allele of probe GP21 closely linked to R1. In three of the four F₁ populations, resulting from crosses between such susceptible plants and susceptible tester plants, resistnat progenies were found. The resistance appeared to be R1-specific. This clearly indicates that in three of the four investigated susceptible plants, the R1 gene was still present but not expressed.     

Islet regeneration during the reversal of autoimmune diabetes in NOD mice

Nonobese diabetic (NOD) mice are a model for type 1 diabetes in humans. Treatment of NOD mice with end-stage disease by injection of donor splenocytes and complete Freund's adjuvant eliminates autoimmunity and permanently restores normoglycemia. The return of endogenous insulin secretion is accompanied by the reappearance of pancreatic beta cells. We now show that live donor male or labeled splenocytes administered to diabetic NOD females contain cells that rapidly differentiate into islet and ductal epithelial cells within the pancreas. Treatment with irradiated splenocytes is also followed by islet regeneration, but at a slower rate. The islets generated in both instances are persistent, functional, and apparent in all NOD hosts with permanent disease reversal.     

Evaluation of the effect of germination on phenolic compounds and antioxidant activities in sorghum varieties

The screening of 50 sorghum varieties showed that, on average, germination did not affect the content in total phenolic compounds but decreased the content of proanthocyanidins, 3-deoxyanthocyanidins, and flavan-4-ols. Independent of germination, there are intervarietal differences in antioxidant activities among sorghum varieties. Phenolic compounds and antioxidant activities were more positively correlated in ungerminated varieties than in germinated ones. Sorghum grains with pigmented testa layer, chestnut color glumes, and red plants had higher contents, larger diversity of phenolic compounds, and higher antioxidant activities than other sorghums. Some red sorghum varieties had higher antioxidant activities (30-80 mumol of Trolox equiv/g) than several sources of natural antioxidants from plant foods. Among varieties used for "to", "dolo", couscous, and porridge preparation, the "dolo"(local beer) varieties had the highest average content and diversity in phenolic compounds as well as the highest antioxidant activities. The biochemical markers determined are useful indicators for the selection of sorghum varieties for food and agronomic properties.     

Horseradish peroxidase-catalyzed cross-linking of feruloylated arabinoxylans with beta-casein

Heterologous conjugates of wheat arabinoxylan and beta-casein were prepared via enzymatic cross-linking, using sequential addition of the arabinoxylan to a mixture of beta-casein, peroxidase, and hydrogen peroxide. The maximal formation of adducts between the beta-casein and the feruloylated arabinoxylan was reached at a protein-to-arabinoxylan ratio of 10:1, in combination with a molar ratio hydrogen peroxide to substrate of 2:1 and a molar protein-to-enzyme ratio between 10(2) and 10(4). The protein-arabinoxylan adducts were separated from the arabinoxylan homopolymers by size exclusion and anion exchange chromatography. The molar ratio protein:arabinoxylan in the purified conjugates varied between 0.1 and 5.6. This is the first report on the large-scale enzymatic preparation of heterologous protein-arabinoxylan conjugates.     

Comparison of content in phenolic compounds,polyphenol oxidase,and peroxidase in grains of fifty sorghum varieties from burkina faso

Analysis of fifty sorghum [Sorghum bicolor (L.) Moench] varieties used in Burkina Faso showed that they have different contents of phenolic compounds, peroxidase (POX), and polyphenol oxidase (PPO). Most of the varieties (82%) had a tannin content less than 0.25% (w/w). POX specific activity was higher than the monophenolase and o-diphenolase specific activities of PPO. For POX, there was a diversity of isoforms among varieties. No clear correlation could be made between the quantitative composition of the grain in phenolics, PPO, and POX, and resistance of plant to pathogens. In general, varieties good for a thick porridge preparation ("t?") had low phenolic compounds content and a medium POX activity. From the red varieties, those used for local beer ("dolo") had a high content in phenolic compounds and PPO, and a low POX activity. The variety considered good for couscous had a low POX content. The characteristics might be useful as selection markers for breeding for specific applications.     

Meteorological interpretation of the chemical composition of rain-water at one measuring site

Rain-water was sampled with 8 wet-only samplers during 42 periods of 2 or 3 days at one coastal site. The following components were determined: H, NH₄, Ca, Mg, K, Na, SO₄, NO₃, Cl, F, Pb, Fe, Br, Mn, V, and Al. The coefficients of variation in the amounts of rainfall did not show a clear relation with wind-speed and amount of rainfall. The same held for the coefficients of variations of the concentrations of the components determined. When the air comes from the land (continental period) the rain shows a larger concentration of components originating from the land. When the air comes from the sea (maritime period) the concentrations of maritime components are greater. Meteorological factors other than winddirection are of minor importance for the determination of the chemical composition of rain-water. On the average NO _x is responsible for generating 36% of the H-ions in rain-water. NH₃ is the most important neutralizing substance. During continental periods the H-concentration would become 2.55 times as high if there were no neutralization by NH₃. Correlations between components are shown. A chemical definition of the continentality of rain is given. The usefulness of this definition is illustrated in connection with a rain-water sample collected during a complicated meteorological event.     

A fractal model of vegetation complexity in Alaska

A methodology using fractals to measure vegetation complexity in three regions of Alaska is presented. Subjective, binomial (0 = simple, 1 = complex) classifications of the complexity of mapped vegetation polygon patterns within continuous forest inventory plots measured in the regions were made by interpreters of aerial photographs. The fractal dimensions of the vegetation patterns within the plots then were estimated. Subsequently, the subjective classifications of the photo-interpreted plots were regressed against fractal dimension by using logistic regression.Assessment of interobserver agreement among the aerial photo interpreters, by using estimated unweighted Kappa coefficients, indicated substantial classification agreement among observers.Examination of general versus regional applicability of the logistic models provided strong support for applicability of a single model to all three regions. The logistic model provides numerical identification of the division between simple and complex patterns. Possible applications beyond the needs of the study are discussed.     

Shedding consistency of strongyle-type eggs in Dutch boarding horses

Faeces of 484 horses were sampled twice with an interval of 6 weeks while anthelmintic therapy was halted. Faecal eggs counts revealed that 267 (55.2%) horses had consistently low numbers of eggs per gram faeces (EPG) (EPG < 100 or = 100), 155 (32.0%) horses had consistently high EPGs (EPG > 100). Horses with consistently high EPGs were more often mares with access to pasture, aged less than 6 or more than 23 years, that were dewormed at intervals longer than 6 months, and were treated for the last time more than 3 months before the start of the study. Horses with consistently low EPGs were more often male horses with no or limited access to pasture, that were dewormed at maximally 6-month intervals, and were aged between 6 and 23 years. The results are an indication that some horses have consistently low EPGs and perhaps could be used as non-treated animals in a selective anthelmintic treatment scheme aimed at the prevention of the development of anthelmintic resistance.