Leaching of dissolved and particulate phosphorus via preferential flow pathways in a forest soil: An approach using zero‐tension lysimeters

Phosphorus (P) fluxes from forest soils are not well understood. For temperate zone forests, there is some evidence from watershed studies that P export occurs mainly in preferential flow pathways during storm events after dry periods. Therefore, we tested the practical applicability of a sampling approach, which should allow for quantifying P concentrations and fluxes. We used zero‐tension lysimeters, which were installed beneath the topsoil and in the subsoil at plots in the Tharandt Forest (Saxony, East Germany). Two storm events after dry periods were simulated by means of experimental sprinkler irrigation. Preferential flow water collected with the zero‐tension lysimeters was analyzed for total P (TP), particulate P (PP), dissolved organic P (DOP) and dissolved inorganic P (DIP), and the respective P fluxes were calculated. The results indicate that the experimental approach is applicable to estimate fluxes of different P fractions in preferential flow. Measured data point toward a distinct flushing of P in the first hours of heavy rainfall events with PP fraction playing a dominant role. In general, P concentrations decreased quickly during the first 2 h of irrigation and then remained constant. Initial concentrations and cumulative fluxes were highest in the subsoil samplers. For a better understanding of underlying processes, further research with a special focus on the PP fraction is necessary.     

Genetic association between milk yield,stayability, and mastitis in Holstein cows under tropical conditions

The objective of this study was to estimate genetic parameters for milk yield, stayability, and the occurrence of clinical mastitis in Holstein cows, as well as studying the genetic relationship between them, in order to provide subsidies for the genetic evaluation of these traits. Records from 5,090 Holstein cows with calving varying from 1991 to 2010, were used in the analysis. Two standard multivariate analyses were carried out, one containing the trait of accumulated 305-day milk yields in the first lactation (MY1), stayability (STAY) until the third lactation, and clinical mastitis (CM), as well as the other traits, considering accumulated 305-day milk yields (Y305), STAY, and CM, including the first three lactations as repeated measures for Y305 and CM. The covariance components were obtained by a Bayesian approach. The heritability estimates obtained by multivariate analysis with MY1 were 0.19, 0.28, and 0.13 for MY1, STAY, and CM, respectively, whereas using the multivariate analysis with the Y305, the estimates were 0.19, 0.31, and 0.14, respectively. The genetic correlations between MY1 and STAY, MY1 and CM, and STAY and CM, respectively, were 0.38, 0.12, and ?0.49. The genetic correlations between Y305 and STAY, Y305 and CM, and STAY and CM, respectively, were 0.66, ?0.25, and ?0.52.     

Floral resource partitioning by ants and bees in a jambolan Syzygium jambolanum (Myrtaceae) agroforestry system in Brazilian Meridional Amazon

The fruit production of flowering plants critically depends on the pollination services provided by animals that compete for flower resources. The output of competitive interactions between ants and bees for inflorescences of jambolan Syzygium jambolanum (Myrtaceae) in an agroforestry system in Brazilian Meridional Amazonian are an interesting system of investigation due the possibility to control variables experimentally. In 20 S. jambolanum individuals we performed 300 treatments in different inflorescences of two strata (upper and lower) as follows: (1) ants exclusion, (2) bees exclusion, and (3) control group where ants and bees could access the inflorescences. There was no difference in the number of inflorescences, volume of nectar and sugar concentration between the strata. Also the visitors considered are distributed equally in the tree??s stratum. When bees were prevented from access the inflorescences, ants dominated more inflorescences only in the lower stratum. On the contrary, when ants were excluded, bees visited more inflorescences only in the upper stratum. We conclude that ants prevent the access to bees and vice versa as the result of different ability of resource utilization and foraging strategies. Thus, preventing the access of ants to the floral nectar could increase the level of nectar available to pollinators of S. jambolanum, thereby increasing productivity and reducing economic losses.     

Sugar fragmentation in the maillard reaction cascade: formation of short-chain carboxylic acids by a new oxidative alpha-dicarbonyl cleavage pathway

The formation of short-chain carboxylic acids was studied in Maillard model systems (90 degrees C, pH 6-10) with emphasis on the role of oxygen and water. The total amount of acetic acid formed did not depend on the reaction atmosphere. In the presence of labeled dioxygen or water (18O2, H2 17O), labeled oxygen was partially incorporated into acetic acid. Thermal treatment of 1-deoxy-d-erythro-2,3-hexodiulose (1) and 3-deoxy-d-erythro-hexos-2-ulose in the presence of 17O-enriched water under alkaline conditions led to acetic and formic acid, respectively, as indicated by 17O NMR spectroscopy. The suggested mechanism involves an oxidative alpha-dicarbonyl cleavage leading to an intermediary mixed acid anhydride that releases the acids, e.g., acetic and erythronic acid, from 1. Similarly, glyceric and lactic acids were formed from 1-deoxy-3,4-hexodiuloses, corroborated by complementary analytical techniques. This paper provides for the first time evidence for the direct formation of acids from C6-alpha-dicarbonyls by an oxidative mechanism and incorporation of a 17OH group into the carboxylic moiety. The experimental data obtained support the coexistence of at least two newly described reaction mechanisms leading to carboxylic acids, i.e., (i) a hydrolytic beta-dicarbonyl cleavage as a major pathway and (ii) an alternative minor pathway via oxidative alpha-dicarbonyl cleavage induced by oxidizing species.     

Fluctuations of element concentrations during the growing season of Polytrichum formosum (Hedw.)

Fourteen elements (Al, Ba, Ca, Cd, Cr, Cu, Fe, K, Mg, Ni, Pb, Sr, Ti, and Zn) were quantitatively determined by AES/ICP in aboveground parts of the endohydric moss Polytrichum formosum (Hedw.) after sampling over regular intervals from 1985 to 1987. With the exception of K, Mg, and Zn all elements showed a large continuous fluctuation (> 30%) during the growing season. Four different patterns of seasonal variation were found: (1) large seasonal variations of element concentrations (～80%) with maximum concentrations in winter and lowest concentrations in the summer months (Al, Fe, Cr, Mg, Pb, and Ti), (2) smaller seasonal variations (～50%) with maximum concentrations in winter and lowest concentrations in summer (Ba, Ca, Cd, Cu, Sr), (3) slight seasonal variations (～30%) with maximum concentrations in the summer (K), and (4) slight seasonal changes (～30%) with maximum concentrations in the winter (Mg and Zn). The relative biological variance of element concentrations between 9 different stands of Polytrichum formosum decreases in the following sequence: Ti, Al, Pb, Fe, Cr, Ni, Ba, Ca, Cu, Cd, K, Mg, Sr, Zn. The relative biological variance of individual elements is generally lower than the variance in element concentrations caused by seasonal changes. Because of its high biological variance for most elements investigated (seasonal as well as between different stands of Polytrichum formosum) this moss should only be used as a passive bioindicator, if all other environmental parameters are standardized.     

Dimeric inhibitors of human salivary alpha-amylase from emmer (Triticum dicoccon Schrank) seeds

The proteins belonging to the cereal trypsin/alpha-amylase inhibitor family are abundant water/salt-soluble flour proteins active against alpha-amylases from several seed parasites and pests and inactive against endogenous alpha-amylases. Three alpha-amylase inhibitor families have been described in cereals that vary in size and are differently expressed among Triticeae seeds. The present work investigates the presence of human salivary alpha-amylase inhibitors in emmer (Triticum dicoccon Schrank) flour. The isolation was obtained by a series of chromatography steps, and the purification progress was monitored through the inhibition of human salivary alpha-amylase activity. The purified fraction was subjected to protein sequencing by tandem mass spectrometry (MSMS) of the tryptic digests obtained after the sample separation on 2-DE. MSMS data indicated that the emmer alpha-amylase inhibitory fraction was composed of two newly identified proteins [emmer dimeric inhibitor 1 (EDI-1) and emmer dimeric inhibitor 2 (EDI-2)] sharing very high identity levels with related proteins from Triticum aestivum.     

Acaricidal properties of extracts from the aerial parts of Hypericum polyanthemum on the cattle tick Boophilus microplus

Laboratory tests were carried out on larvae and adults of the cattle tick Boophilus microplus to determine the toxicity of n-hexane and crude methanolic extracts of Hypericum polyanthemum (Guttiferae) using the larval immersion test (LIT) and adult immersion test (AIT). In the AIT, the effectiveness of treatment against engorged females was assessed by measuring egg production: the n-hexane extract was found to have a small effect on the egg laying at the highest concentration (19.2% of egg-laying inhibition) whilst the crude methanolic extract did not affect the egg production. For the LIT the n-hexane extracts were highly toxic to the larvae at all the concentrations (100% of mortality). The crude methanolic extract was also toxic to the larvae at higher concentrations killing 100, 96.7, 84.7 and 52.7% at the concentrations of 50, 25, 12.5, and 6.25 mg/ml, respectively, 48 h after the immersion of the acarus.