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1.
From sludge obtained from the sewage digester plant in Stuttgart-Möhringen a strictly anaerobic bacterium was enriched and isolated with methyl chloride as the energy source. The isolate, which was tentatively called strain MC, was nonmotile, gram-positive, and occurred as elongated cocci arranged in chains. Cells of strain MC formed about 3 mol of acetate per 4 mol of CH3Cl consumed, indicating that the organism was a homoacetogenic bacterium fermenting methyl chloride plus CO2 according to:
The organism grew with 2–3% methyl chloride in the gas phase at a doubling time of near 30 h. Dichloromethane was not utilized. The bacterium also grew on carbon monoxide, H2 plus CO2, and methoxylated aromatic compounds. Optimal growth with methyl chloride was observed at 25°C and pH 7.3–7.7. The G+C-content of the DNA was 47.5±1.5%. The methyl chloride conversion appeared to be inducible, since H2 plus CO2-grown cells lacked this ability. From the morphological and physiological characteristics, the isolate could not be affiliated to a known species. 相似文献
2.
Demonstration of a beta-casomorphin immunoreactive material in the plasma of newborn calves after milk intake 总被引:1,自引:0,他引:1
Martin Umbach Hansjörg Teschemacher Karina Praetorius Richard Hirschhäuser Hartwig Bostedt 《Regulatory peptides》1985,12(3):223-230
Blood was collected from newborn calves before and after their first milk intake after birth; extracts of plasma were assayed by radioimmunoassay for the presence of beta-casomorphin-7 immunoreactive materials. No beta-casomorphin immunoreactivity was found in samples collected before milk ingestion; however, in samples collected after milk ingestion a beta-casomorphin-7 immunoreactive material was detected. Chromatographic characterization showed that this material was not identical with beta-casomorphin-7 but might rather represent a precursor thereof. The material proved resistant to enzymatic attack during a 30-min incubation period at 37 degrees C in the plasma of newborn calves, whereas beta-casomorphin-7 was degraded under these conditions. A physiological significance of beta-casomorphin-7 eventually cleaved from such a precursor material at any site in the newborn mammal is suggested. 相似文献
3.
4.
Ion balance in tomato cultivars differing in salt tolerance. I. Sodium and potassium accumulation and fluxes under moderate salinity 总被引:1,自引:0,他引:1
The magnitude of sodium and potassium fluxes in Lycopersicon escutentum cuhivars Ace and Edkawi (Edkawi is considered more sait-tolerant I was evaluated in planls grown for 10 days in aerated Hoagland solution with the addition of 25 or 100 mM NaCl. Ion accumulatiun in different plant pans, ion concentration in xylem exudate. transpiration and membrane leakiness were measured. Both cultivars responded very similarly to these levels of salinity in terms of growth. No conspicuous differences in membrane leakiness were observed. Net uprake rates were calculated from ion contents data. Potassium uptake rates were lower in salinized planls than in controls, especially in cv. Aee. Potassium/sodium selectivity ratios were much higher in Edkawi than in Ace. and higher in shoot uptake rates than in xy lem exudate. This indicates that Edakw i has a higher capacity to retain potassium under salinity, a character which could contribute to its salt-tolerance. 相似文献
5.
Karina Reiter Christoph Plutzar Dietmar Moser Philipp Semenchuk Karl-Heinz Erb Franz Essl Andreas Gattringer Helmut Haberl Fridolin Krausmann Bernd Lenzner Johannes Wessely Sarah Matej Robin Pouteau Stefan Dullinger 《Global Ecology and Biogeography》2023,32(6):855-866
Aim
Land use is the most pervasive driver of biodiversity loss. Predicting its impact on species richness (SR) is often based on indicators of habitat loss. However, the degradation of habitats, especially through land-use intensification, also affects species. Here, we evaluate whether an integrative metric of land-use intensity, the human appropriation of net primary production, is correlated with the decline of SR in used landscapes across the globe.Location
Global.Time period
Present.Major taxa studied
Birds, mammals and amphibians.Methods
Based on species range maps (spatial resolution: 20 km × 20 km) and an area-of-habitat approach, we calibrated a “species–energy model” by correlating the SR of three groups of vertebrates with net primary production and biogeographical covariables in “wilderness” areas (i.e., those where available energy is assumed to be still at pristine levels). We used this model to project the difference between pristine SR and the SR corresponding to the energy remaining in used landscapes (i.e., SR loss expected owing to human energy extraction outside wilderness areas). We validated the projected species loss by comparison with the realized and impending loss reconstructed from habitat conversion and documented by national Red Lists.Results
Species–energy models largely explained landscape-scale variation of mapped SR in wilderness areas (adjusted R2-values: 0.79–0.93). Model-based projections of SR loss were lower, on average, than reconstructed and documented ones, but the spatial patterns were correlated significantly, with stronger correlation in mammals (Pearson's r = 0.68) than in amphibians (r = 0.60) and birds (r = 0.57).Main conclusions
Our results suggest that the human appropriation of net primary production is a useful indicator of heterotrophic species loss in used landscapes, hence we recommend its inclusion in models based on species–area relationships to improve predictions of land-use-driven biodiversity loss. 相似文献6.
Karina Boege 《Oikos》2004,107(3):541-548
Induced changes in plant quality are hypothesized to reduce herbivore numbers and subsequent damage to the plant. The resultant decrease in herbivory may be due to direct negative impacts on herbivores, through the reduction in foliage quality as food, or due to indirect effects of plant-induced traits interacting with the third trophic level, increasing predation and parasitism rates on herbivores. The relative importance of induced responses as direct and/or indirect defenses has not been evaluated in natural systems. Moreover, few studies have evaluated the influence of early-season damage on late-season herbivory in natural systems, particularly in the tropics. The presence of induced responses and subsequent impact on folivory as a consequence of early-season damage were evaluated in three plant species ( Croton pseudoniveus , Bursera instabilis and Piper stipulaceum ) in a tropical dry forest in Mexico. A two-factorial experiment was applied to determine if induced responses influenced subsequent herbivory directly, by reducing foliage quality, or indirectly, through their interaction with parasitoids and predatory arthropods. Plants from all three species with reduced early-season damage had higher herbivory rates through the rest of the growing season, compared to plants that were damaged during leaf expansion. Chemical analyses showed that early-season damage induced the production of total phenolics and condensed tannins for C. pseudoniveus and B. instabilis , respectively. The mechanism by which these compounds affected subsequent herbivory was most likely by directly reducing foliage quality as food for herbivores, given that predatory arthropods and parasitoids had no effects on herbivory in this study. I conclude that early-season damage in these three species influenced later-season herbivory through the induction of plant responses that may act to reduce plant quality as food for herbivores. 相似文献
7.
Nitrogen fixation and assimilation in nodules and roots were studied in soybean (Glycine max L.) exposed to different levels of aluminium (Al) stress (0, 50, 200 and 500 μM). Al at 500 μM induced oxidative stress,
which became evident from an increase in lipid peroxidation accompanied by a concomitant decline in antioxidant enzyme activities
and leghaemoglobin breakdown. Consequently, there was also a reduction in nitrogenase activity. However, the leghaemoglobin
levels and nitrogenase activity were unexpectedly found to be higher in nodules when the plants were treated with 200 μM Al.
Of the enzymes involved in nitrogen assimilation, the activity of glutamate dehydrogenase-NADH was reduced in nodules under
Al stress, but it was significantly higher in roots at 500 μM Al as compared to that in the control. In nodules, the glutamine
synthetase/glutamate synthase-NADH pathway, assayed in terms of activity and expression of both the enzymes, was inhibited
at >50 μM Al; but in roots this inhibitory effect was apparent only at 500 μM Al. No significant changes in ammonium and protein
contents were recorded in the nodules or roots when the plants were treated with 50 μM Al. However, Al at ≥200 μM significantly
increased the ammonium levels and decreased the protein content in the nodules. But these contrasting effects on ammonium
and protein contents due to Al stress were observed in the roots only at 500 μM Al. The results suggest that the effect of
Al stress on nitrogen assimilation is more conspicuous in nodules than that in the roots of soybean plants. 相似文献
8.
Mapping QTL for production traits in segregating Piétrain pig populations using genome‐wide association study results of F2 crosses 下载免费PDF全文
In this study, genome‐wide association study (GWAS) results of porcine F2 crosses were used to map QTL in outcross Piétrain populations. For this purpose, two F2 crosses (Piétrain × Meishan, n = 304; Piétrain × Wild Boar, n = 291) were genotyped with the PorcineSNP60v2 BeadChip and phenotyped for the dressing yield, carcass length, daily gain and drip loss traits. GWASs were conducted in the pooled F2 cross applying single marker mixed linear models. For the investigated traits, between two and five (in total 15) QTL core regions, spanning 250 segregating SNPs around a significant trait‐associated peak SNP, were identified. The SNPs within the QTL core regions were subsequently tested for trait association in two outcross Piétrain populations consisting of 771 progeny‐tested boars and 210 sows with their own performance records. In the sow (boar) dataset, five (eight) of the 15 mapped QTL were validated. Hence, many QTL mapped in the F2 crosses (with Piétrain as a common founder breed) are still segregating in the current Piétrain breed. This confirms the usefulness of existing F2 crosses for mapping QTL that are still segregating in the recent founder breed generation. The approach utilizes the high power of an F2 cross to map QTL in a breeding population for which it is not guaranteed that they would be found using a GWAS in this population. 相似文献
9.
Christine Ackerman Adam E. Locke Eleanor Feingold Benjamin Reshey Karina Espana Janita Thusberg Sean Mooney Lora J.H. Bean Kenneth J. Dooley Clifford L. Cua Roger H. Reeves Stephanie L. Sherman Cheryl L. Maslen 《American journal of human genetics》2012,91(4):646-659
About half of people with trisomy 21 have a congenital heart defect (CHD), whereas the remainder have a structurally normal heart, demonstrating that trisomy 21 is a significant risk factor but is not causal for abnormal heart development. Atrioventricular septal defects (AVSD) are the most commonly occurring heart defects in Down syndrome (DS), and ∼65% of all AVSD is associated with DS. We used a candidate-gene approach among individuals with DS and complete AVSD (cases = 141) and DS with no CHD (controls = 141) to determine whether rare genetic variants in genes involved in atrioventricular valvuloseptal morphogenesis contribute to AVSD in this sensitized population. We found a significant excess (p < 0.0001) of variants predicted to be deleterious in cases compared to controls. At the most stringent level of filtering, we found potentially damaging variants in nearly 20% of cases but fewer than 3% of controls. The variants with the highest probability of being damaging in cases only were found in six genes: COL6A1, COL6A2, CRELD1, FBLN2, FRZB, and GATA5. Several of the case-specific variants were recurrent in unrelated individuals, occurring in 10% of cases studied. No variants with an equal probability of being damaging were found in controls, demonstrating a highly specific association with AVSD. Of note, all of these genes are in the VEGF-A pathway, even though the candidate genes analyzed in this study represented numerous biochemical and developmental pathways, suggesting that rare variants in the VEGF-A pathway might contribute to the genetic underpinnings of AVSD in humans. 相似文献
10.
Athanasios Paschalis Simone Fatichi Jakob Zscheischler Philippe Ciais Michael Bahn Lena Boysen Jinfeng Chang Martin De Kauwe Marc Estiarte Daniel Goll Paul J. Hanson Anna B. Harper Enqing Hou Jaime Kigel Alan K. Knapp Klaus S. Larsen Wei Li Sebastian Lienert Yiqi Luo Patrick Meir Julia E. M. S. Nabel Rom Ogaya Anthony J. Parolari Changhui Peng Josep Peuelas Julia Pongratz Serge Rambal Inger K. Schmidt Hao Shi Marcelo Sternberg Hanqin Tian Elisabeth Tschumi Anna Ukkola Sara Vicca Nicolas Viovy Ying‐Ping Wang Zhuonan Wang Karina Williams Donghai Wu Qiuan Zhu 《Global Change Biology》2020,26(6):3336-3355
Changes in rainfall amounts and patterns have been observed and are expected to continue in the near future with potentially significant ecological and societal consequences. Modelling vegetation responses to changes in rainfall is thus crucial to project water and carbon cycles in the future. In this study, we present the results of a new model‐data intercomparison project, where we tested the ability of 10 terrestrial biosphere models to reproduce the observed sensitivity of ecosystem productivity to rainfall changes at 10 sites across the globe, in nine of which, rainfall exclusion and/or irrigation experiments had been performed. The key results are as follows: (a) Inter‐model variation is generally large and model agreement varies with timescales. In severely water‐limited sites, models only agree on the interannual variability of evapotranspiration and to a smaller extent on gross primary productivity. In more mesic sites, model agreement for both water and carbon fluxes is typically higher on fine (daily–monthly) timescales and reduces on longer (seasonal–annual) scales. (b) Models on average overestimate the relationship between ecosystem productivity and mean rainfall amounts across sites (in space) and have a low capacity in reproducing the temporal (interannual) sensitivity of vegetation productivity to annual rainfall at a given site, even though observation uncertainty is comparable to inter‐model variability. (c) Most models reproduced the sign of the observed patterns in productivity changes in rainfall manipulation experiments but had a low capacity in reproducing the observed magnitude of productivity changes. Models better reproduced the observed productivity responses due to rainfall exclusion than addition. (d) All models attribute ecosystem productivity changes to the intensity of vegetation stress and peak leaf area, whereas the impact of the change in growing season length is negligible. The relative contribution of the peak leaf area and vegetation stress intensity was highly variable among models. 相似文献