Characteristic volatiles from young and aged fruiting bodies of wild Polyporus sulfureus (Bull.:Fr.) Fr

The volatile compounds of fresh fruiting bodies of wild Polyporus sulfureus (Bull.:Fr.) Fr. growing on oak trees were isolated by continuous liquid-liquid extraction (CLLE) and investigated by high-resolution gas chromatography-mass spectrometry (HRGC-MS) on two GC columns of different polarity (DB-5 and ZB-WAX), and by gas chromatography-olfactometry (GC-O). A total of 40 major volatile compounds from the young samples were identified and semiquantified. Five odorous compounds were determined to be responsible for the characteristic flavor of young Polyporus sulfureus: 1-octen-3-one, 1-octen-3-ol, 3-methylbutanoic acid, phenylethanol, and phenylacetic acid. Four volatiles investigated by GC-O and detected by GC-MS were determined as the characteristic odorants of aged species: 2-methylpropanoic acid, butanoic acid, 3-methylbutanoic acid, and phenylacetic acid. The comparative results revealed that the volatile composition of the fruiting bodies even from the same fungal species may greatly vary with its host, location, and age.     

From farm to fork--Mycobacterium avium ssp. paratuberculosis (MAP) as zoonotic agent?

Mycobacterium avium ssp. paratuberculosis (MAP) is the causative agent of the paratuberculosis (Para Tb) in ruminants. In addition, this pathogen has been suspected to be implicated in the pathogenesis of Morbus Crohn disease (MC), causing chronic inflammatory intestine changes of humans. The participation of MAP in this illness is discussed intensively and has very contradictory opinions. On the one hand several times succeeded in proving MAP DNA in changed human tissues as well as, in recent time, the bacteria has been isolated from patient's blood. On the other hand there are many publications which support the opposite opinion. In critical evaluation of already available data, therefore the hypothesis can be formulated that MAP could possibly take part in the MC of humans. The reliable verification of this hypothesis will only be possible, if the diagnostic procedures can be refined upon the substantial deficit concerning the sensitivity and/or specificity of the diagnostic methods. In addition, till now there is lack of optimized statistically case control studies. The conceivable transmission of the bacteria to humans by the direct animal contact has been considered as possible vector, furthermore, MAP has been detected in pasteurised milk and other food of animal origin. The prevalence data, usually estimated by ELISA for milk cattle stock show over 80% prevalence in many counties of the Federal Republic of Germany with an individual case prevalence ranging between 1% and 17% in different stocks. Comparable data are present also from other countries as well as for small ruminants. MAP has been concerned as a global problem, moreover the high spreading rate of MAP in wild animal populations as well as the considerable ability of the bacteria to survive in different stages of the infectious- and contamination-cycle, which might hardly be broken through. Thus it requires intensive research efforts for the development of the methodical diagnostic process as basis for valid epidemiological investigations of animals, humans and food.     

甘蓝型油菜-萝卜附加系中萝卜染色体的（dp）RAPD标记

在已掌握甘蓝型油菜-萝卜附加系染色体构成,并构建萝卜分子连锁图谱的基础上,以甘蓝型油菜?萝卜附加系为材料,利用(dp)RAPD分子标记技术,筛选附加系中外源萝卜9条染色体(A～I)的分子标记,为进一步研究萝卜染色体与连锁群对应关系奠定基础。试验筛选了576个随机引物(组合),有413个能从附加系中扩增出萝卜染色体的(dp)RAPD标记,平均有效引物(组合)占71·7%,其中RAPD反应有效引物率67·7%,dpRAPD反应有效引物率73·2%。试验共得到899个萝卜染色体(dp)RAPD标记,包括354个RAPD标记和545个dpRAPD标记,覆盖萝卜整个基因组的全部9条染色体,不同染色体的标记数目变化范围在41～160,其中最多的是染色体C,最少的是染色体I。     

Increasing control reliability of <Emphasis Type="Italic">Orobanche cumana </Emphasis>through integration of a biocontrol agent with a resistance-inducing chemical

Fusarium oxysporum Schlecht. f.sp. orthoceras (Appel & Wollenw.) Bilai is a potential biocontrol agent against the root-parasitic weed Orobanche cumana. In pot experiments with different sunflower cultivars, the application of F. oxysporum was combined with a treatment of BTH (Benzo(1,2,3)thiadiazole-7-carbothioic acid S-methyl ester), a product known to induce resistance against O. cumana in sunflower. The combined treatments resulted in highly reliable control and sometimes in increased control level compared to the Fusarium treatment alone. In laboratory experiments, no enhancing effect of BTH on virulence and growth of the fungus was observed. Future experiments should further investigate the basic mechanisms of the effect achieved by combining the two control strategies as well as the transfer of this innovative control approach into field experiments.     

萝卜-甘蓝型油菜中萝卜基因组的RAPD与dpRAPD分析效率研究

应用RAPD与dpRAPD方法鉴定萝卜-甘蓝型油莱中萝卜基因组,筛选了140条随机引物。结果表明,平均每条引物(组合)能产生的萝b基因组特异标记数dpRAPD高于RAPD,分别为1．69和1．33;在dpRAPD扩增产物中有77．6％谱带清晰易辨,略高于RAPD(75．4％)。两者所检测到的萝卜基因组标记大部分为各自特异的扩增产物。由于结合了荧光标记引物,dpRAPD反应产物可在Genetic Analyzer上分离检测,因此能检测到100bp以下的小片段DNA。     

Impact of horse grazing and feeding on phosphorus concentrations in soil and drainage water

The number of horses in Sweden has increased, from 77 300 in 1970 to 283 000 in 2003 (ca. 250%). These horses are kept on 300 000 ha, which represents 10% of total agricultural land in Sweden. Maximum recommended livestock density in Sweden is 2.5 units/ha for grazed pasture, but no limits have yet been set for outdoor keeping and feeding areas (paddocks) for horses. This study characterized the potential risk of phosphorus (P) losses from a horse paddock established on a heavy clay soil with a stocking rate of 3.75 livestock units/ha compared with nearby arable land. The horse paddock received 15 kg P/ha/yr and 75 kg N/ha/yr through horse excreta, while annual input of P and N to the adjacent arable land was 13 and 112 kg/ha, respectively. There was no significant difference in water‐soluble P (WSP) in fresh and dried soil samples between the horse paddock (mean values: 0.62 and 0.43 mg/100 g soil; n = 15) and the arable field (mean values: 0.52 and 0.37 mg/100 g soil; n = 5). In contrast, phosphorus extractable in ammonium acetate lactate (extractable P) in the topsoil of the horse paddock (mean: 15 mg/100 g soil) was significantly higher (P = 0.03; n = 15) than in the arable land, whereas total P extracted with nitric acid (total P) showed no statistically significant differences. Furthermore, there was no significant difference in lactate‐extractable iron and aluminium (extractable Fe and Al), organic carbon (C), total nitrogen (N) or phosphorus sorption index between the two parcels of land. However, the degree of P saturation in soil was significantly higher (P = 0.02; n = 15) in the horse paddock. Extractable Al and Fe were highly correlated to extractable P (P < 0.001; n = 69), the correlation being negative for Al. No relationship was found with calcium, but soil C content was found to be correlated with extractable P (P < 0.001; n = 69). Over the past 8 yr, high P concentrations (up to 1.5 mg/L), mainly in dissolved reactive form, have been recorded in drainage water from the grazed catchment. We concluded that horse grazing at high stocking rates (>2.5 livestock units/ha) may pose a risk of high P losses to nearby water bodies.     

A melanocortin 1 receptor allele suggests varying pigmentation among Neanderthals

The melanocortin 1 receptor (MC1R) regulates pigmentation in humans and other vertebrates. Variants of MC1R with reduced function are associated with pale skin color and red hair in humans of primarily European origin. We amplified and sequenced a fragment of the MC1R gene (mc1r) from two Neanderthal remains. Both specimens have a mutation that was not found in approximately 3700 modern humans analyzed. Functional analyses show that this variant reduces MC1R activity to a level that alters hair and/or skin pigmentation in humans. The impaired activity of this variant suggests that Neanderthals varied in pigmentation levels, potentially on the scale observed in modern humans. Our data suggest that inactive MC1R variants evolved independently in both modern humans and Neanderthals.     

Molecular architecture of the multiprotein splicing factor SF3b

The splicing factor SF3b is a multiprotein complex essential for the accurate excision of introns from pre-messenger RNA. As an integral component of the U2 small nuclear ribonucleoprotein (snRNP) and the U11/U12 di-snRNP, SF3b is involved in the recognition of the pre-messenger RNA's branch site within the major and minor spliceosomes. We have determined the three-dimensional structure of the human SF3b complex by single-particle electron cryomicroscopy at a resolution of less than 10 angstroms, allowing identification of protein domains with known structural folds. The best fit of a modeled RNA-recognition motif indicates that the protein p14 is located in the central cavity of the complex. The 22 tandem helical repeats of the protein SF3b155 are located in the outer shell of the complex enclosing p14.     

Relationship between water and nitrogen uptake in nitrate‐ and ammonium‐supplied Phaseolus vulgaris L. plants

Sole ammonium supply provokes negative effects on dry‐mass formation, leaf growth, and water uptake of ammonium‐sensitive plants. To study the effects of N form on nutrient and water uptake and aquaporin expression, French bean plants were grown in a split‐root system. Five treatments were compared: homogeneous nitrate (NN) and ammonium (AA) supply; spatially separated supply of nitrate and ammonium (NA); and half of the root system supplied with N‐free nutrient solution, the other half with either nitrate (N0) or ammonium (A0). Ten days after onset of treatments, root dry mass (DM) and water‐uptake rate (WUR) were significantly reduced under ammonium compared to nitrate supply. WUR from nitrate‐supplied vessels was 80% higher than that from N‐free nutrient solution, while WUR from N‐free nutrient solution was 130% higher than that from ammonium‐supplied vessels. Potassium uptake was lower under ammonium supply and the ratio of N : K uptake of treatment AA was significantly higher compared to others. High K uptake from N‐free nutrient solution of A0 plants resulted in a ratio of N : K uptake comparable to nitrate‐supplied plants, but shoot growth resembled that to plants under sole ammonium supply. Within 24 h after onset of treatments, expression of aquaporin was lower under ammonium compared to nitrate supply. From these data, it can be concluded that reduced root water transport under ammonium supply is directly related to aquaporin activity.     

Bulk soil C to N ratio as a simple measure of net N mineralization from stabilized soil organic matter in sandy arable soils

Investigations of 23 northwestern German sandy Ap horizons (mean clay content 35 g kg⁻¹), that had higher organic matter (OM) levels than expected for sands, showed that the bulk soil C to N ratio reliably indicated the release of N from stabilized OM. Soils were incubated at 35 °C for 200 days under aerobic conditions. Cumulative N release curves were split into N released from fresh materials (N_fast) and N released from the larger pool of stabilized, older OM (N_slow rates, 0.06-0.77 μg N g⁻¹ soil d⁻¹, or 0.7-49 μg N g⁻¹ OM). Correlating the N_slow rates with total N contents of soils yielded no satisfactory relationships while their relationship with C to N ratios was very close (negative exponential, R²=0.88). Low rates of N release (N_slow) per unit of OM occurred if C to N exceeded 15. This was associated with historical factors like podzolization, calluna heathland, plaggen fertilization or a combination of these.