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71.
Recent advances in soil C saturation concepts have increased our understanding of soil C storage and mineralization without
explicit links to N retention and saturation theories. Here, we exploit soil texture and organic matter (OM) gradients in
a Maryland, USA hardwood forest to test hypotheses that link soil organic C saturation with soil 15N retention and nitrification. At our site, mineral-associated OM (MAOM) N concentrations in the silt + clay particle fraction
(g MAOM-N g silt + clay−1) were negatively correlated with the fraction of NH4-N transferred to MAOM during a 3-day in situ incubation (R = −0.85), but positively correlated with potential net nitrification (R = 0.76). Moreover, the fraction of NH4-N transferred to MAOM was negatively correlated with potential net nitrification (R = −0.76). Due to physico-chemical stabilization mechanisms, MAOM is considered to be resistant to mineralization. Carbon
saturation theory suggests that the proportion of new C inputs that can be stabilized in MAOM decreases in proportion to the
amount of C already present in the fraction; C inputs not stabilized in MAOM are susceptible to rapid mineralization. We demonstrate
that NH4-N stabilization in MAOM is similar to C stabilization in MAOM and associated with nitrification, thereby extending soil C
saturation theory to mineral N and linking it with N retention and saturation theories. These data and concepts complement
N saturation models that emphasize vegetation type, N input levels, and microbial turnover. Incorporating the OM retention
capacity of fine mineral particles into N saturation theory can improve predictions of N saturation rates and resolve inconsistent
relationships between soil organic matter, texture, N mineralization, and N retention. 相似文献
72.
New Hampshire eggs were injected with iproniazid into the yolk sac at day 2 of incubation by means of a tiny hole in the shell. A control group was injected with normal saline and a second group was left unopened. Iproniazid in the doses we used proved to be lethal for approximately 50% of the chick embryos, while we cannot demonstrate other developmental alterations, either in the macroscopical or in the serial histological study. 相似文献
73.
Manuel Azcrate‐García Magdalena Ruiz‐Rodríguez Silvia Díaz‐Lora Cristina Ruiz‐Castellano Juan Jos Soler 《Journal of avian biology》2019,50(3)
Nestlings of most avian species produce faecal sacs, which facilitate the removal of nestlings’ excrements by parents, thereby reducing proliferation of potentially pathogenic microorganisms and/or detectability by predators and parasites. The nest microbial environment that birds experience during early life might also affect their development and thus, faecal sacs facilitating parental removal may be a strategy to decrease bacterial contamination of nests that could harm developing nestlings. Here, we tested this hypothesis by experimentally broken faecal sacs and spreading them in nests of spotless starlings Sturnus unicolor, thereby avoiding their removal by adults. In accordance with the hypothesis, experimental nests harboured higher bacterial density than control nests. Nestlings in experimental nests were of smaller size (tarsus length) and experienced lower probability of survival (predation) than those in control nests. Moreover, nestlings in experimental nests tended to suffer more from ectoparasites than those in control nests. We discuss the possible pivotal role of bacteria producing chemical volatiles that ectoparasites and predators might use to find avian nests, and that could explain our experimental results in starlings. 相似文献
74.
Niche and dispersal ability are key traits for explaining the geographical structuring of species into discrete populations, and its evolutionary significance. Beyond their individual effects, the interplay between species niche and its geographic limits, together with the evolutionary lability of dispersal ability, can underpin trait diversification and speciation when exposed to gradients of selection. In this issue of Molecular Ecology, two complementary papers demonstrate how evolutionary lability for dispersal ability linked to niche shift can drive such a model in a context that includes selection. Both papers investigate the evolution of dispersal limitation in arthropods across altitudinal gradients, but using taxa with contrasting ecologies. McCulloch et al. (2019) investigate the evolution of wing loss at higher altitudes in stoneflies, a taxon inhabiting freshwater systems. Suzuki et al. (2019) report a similar phenomenon, but involving wing reduction at higher altitudes in scorpionflies, a taxon associated with moist terrestrial habitats. Here, we compare and contrast the results of both studies to explore their broader implications for understanding diversification and speciation within arthropods. 相似文献
75.
Pastor J Oyarzabal J Saluste G Alvarez RM Rivero V Ramos F Cendón E Blanco-Aparicio C Ajenjo N Cebriá A Albarrán MI Cebrián D Corrionero A Fominaya J Montoya G Mazzorana M 《Bioorganic & medicinal chemistry letters》2012,22(4):1591-1597
PIM kinases have become targets of interest due to their association with biochemical mechanisms affecting survival, proliferation and cytokine production. 1,2,3-Triazolo[4,5-b]pyridines were identified as PIM inhibitors applying a scaffold hopping approach. Initial exploration around this scaffold and X-ray crystallographic data are hereby described. 相似文献
76.
Martínez González S Hernández AI Varela C Rodríguez-Arístegui S Alvarez RM García AB Lorenzo M Rivero V Oyarzabal J Rabal O Bischoff JR Albarrán M Cebriá A Alfonso P Link W Fominaya J Pastor J 《Bioorganic & medicinal chemistry letters》2012,22(5):1874-1878
Phosphoinositide-3-kinase (PI3K) is an important target for cancer therapeutics due to the deregulation of its signaling pathway in a wide variety of human cancers. We describe herein a novel series of imidazo[1,2-a]pyrazines as PI3K inhibitors. 相似文献
77.
AIMS: To evaluate the inhibition effectiveness of Lactobacillus curvatus CRL705 used as a bioprotective culture and of its bacteriocins, lactocin 705 and lactocin AL705, against Listeria innocua, Brochothrix thermosphacta and indigenous lactic acid bacteria (LAB) in vacuum-packaged meat stored at 2 degrees C. METHODS AND RESULTS: The live culture of Lact. curvatus CRL705 as well as synthetic lactocin 705 and purified lactocin AL705 were shown to be similarly effective in preventing the growth of B. thermosphacta and L. innocua in meat discs in contrast to control samples in which these micro-organisms grew rapidly, their numbers increasing by 3.0- and 2.1-log cycles respectively. In addition, indigenous LAB population showed a lower growth rate in the presence of lactocin 705. Bacteriocin activity was detected in the meat discs during 36 days at 2 degrees C irrespective of the biopreservation strategy applied. Changes in pH were not significantly different in meat discs treated with the protective culture when compared with control samples. CONCLUSIONS: Lactobacillus curvatus CRL705 and the produced bacteriocins, lactocin 705 and lactocin AL 705, were effective in inhibiting L. innocua and B. thermosphacta. The use of the bioprotective culture in refrigerated vacuum-packaged fresh meat would be more feasible from an economic and legal point of view. SIGNIFICANCE AND IMPACT OF THE STUDY: Establishment of biopreservation as a method to ensure the microbiological safety of vacuum-packaged fresh meat at 2 degrees C. 相似文献
78.
Angel A. Recio Despaigne Jeferson G. Da Silva Ana Cerúlia M. do Carmo Oscar E. Piro Eduardo E. Castellano Heloisa Beraldo 《Inorganica chimica acta》2009,362(7):2117-2122
2-Benzoylpyridine-phenylhydrazone (H2BzPh), 2-benzoylpyridine-para-chloro-phenylhydrazone (H2BzpClPh), and 2-benzoylpyridine-para-nitro-phenyl (H2BzpNO2Ph) hydrazone were obtained and fully characterized, as well as their zinc(II) complexes [Zn(H2BzPh)Cl2] (1), [Zn(H2BzClPh)Cl2] (2) and [Zn(H2BzpNO2Ph)Cl2] (3). During the syntheses of complex 1 a second product crystallized, which was characterized as [Zn(2BzPh)2] (1a). Upon re-crystallization in 1:9 DMSO:acetone conversion of 2 into [Zn(H2BzpClPh)Cl2] · H2O (2a) and of 3 into [Zn(2BzpNO2Ph)Cl(DMSO)] (3a) occurred. The crystal structures of 1a, 2a and 3a were determined. In 1a the two nearly perpendicular H2BzPh ligands give rise to a distorted octahedral environment around the metal. The 5-fold coordination around the metal is completed with two chloride ions in 2a and with one chloride and one oxygen atom from DMSO in 3a. 相似文献
79.
80.