Model organic compounds differ in their effects on pH changes of two soils differing in initial pH

The mechanisms by which organic materials affect soil pH are not fully understood. This study for the first time compared the short-term effect of various model organic compounds on pH change of two soils differing in initial pH (Podosol of pH 4.4 and Tenosol of pH 6.1). Eight organic compounds, representing common compounds in plant residues, were selected based on the number and type of chemical functional groups. The addition of organic acids (acetic, malic, citric, and benzoic acid) reduced soil pH immediately due to H⁺ dissociation. The magnitude of pH decrease depended on the rate of application, degree of dissociation of the acids, and initial soil pH. During a subsequent incubation, pH was slowly restored as these compounds were decomposed. The degree to which pH was restored was reduced with increasing addition rate. The production of H⁺ ions was increased with increasing rate of acid addition and decreased over time. When potassium citrate (organic anion) was added, soil pH increased due to H⁺ consumption upon decomposition. Compounds with amine groups (glucosamine hydrochloride) and less easily decomposable compounds (phenol) did not significantly alter pH during 16-day shaking. Changes in pH after glucose addition were relatively small compared with other compounds and were not expected because hydroxyl chemical groups of glucose are neutral. The present study demonstrated that the addition of model organic compounds to soil caused soil pH to increase, decrease, or remains unaffected. The extent and direction of pH change was dependent on the chemical functional group, addition rate, decomposition, and the initial soil pH.     

Evaluation of Nebraska Waxy Sorghum Hybrids for Ethanol Production

To evaluate the ethanol production performance of waxy sorghum hybrids and the effects of location and harvest year on ethanol yield, samples of four waxy sorghum hybrids collected from two Nebraska locations (Mead and Lincoln) in both 2009 and 2010 were tested for ethanol production in a dry‐grind process. No significant difference (P = 0.216) in starch contents was observed among the four hybrids, but starch contents of the hybrids were significantly affected by growth location (P = 0.0001) and harvest year (P = 0.0258). Location, hybrid, and harvest year all had significant effects on ethanol fermentation efficiency in the dry‐grind process. Lincoln sorghum samples showed higher (P = 0.022) ethanol fermentation efficiency (90.4%) than did Mead sorghum samples (90.0%). Sorghums harvested in 2010 had higher (P < 0.001) ethanol fermentation efficiency (91.1%) than those harvested in 2009 (89.3%). The 2009 sorghum flours had more amylose‐lipid complexes than the 2010 samples did, and amylose‐lipid complexes as previously reported had adverse effects on ethanol fermentation. Residual starch contents in distillers dried grains with solubles (DDGS) were significantly affected by hybrid and harvest year (P < 0.0001), but we observed no difference in protein content in DDGS from the four hybrids.     

Small cetacean captures in Peruvian artisanal fisheries: High despite protective legislation

We detail the first direct, at sea monitoring of small cetacean interactions with Peruvian artisanal drift gillnet and longline fisheries. A total of 253 small cetaceans were captured during 66 monitored fishing trips (Gillnet: 46 trips; Longline: 20 trips) from the port of Salaverry, northern Peru (8^o14′S, 78^o59′W) from March 2005 to July 2007. The most commonly captured species were common dolphins (Delphinus spp.) (47%), dusky dolphins (Lagenorhynchus obscurus) (29%), common bottlenose dolphins (Tursiops truncatus) (13%) and Burmeister’s porpoises (Phocoena spinipinnis) (6%). An estimated 95% of common dolphin bycatch was of long-beaked common dolphins (Delphinus capensis). Overall bycatch per unit effort for gillnet vessels (mean ± sd) was estimated to be 0.65 ± 0.41 animals.set⁻¹ (range 0.05-1.50) and overall catch (bycatch and harpoon) was 4.96 ± 3.33 animals.trip⁻¹ (range 0.33-13.33). Based upon total fishing effort for Salaverry we estimated the total annual average small cetacean bycatch by gillnet vessels as 2412 animals.year⁻¹ (95% CI 1092-4303) for 2002-2007. This work indicates that, in at least one Peruvian port, bycatch and harpooning of small cetaceans persist at high levels and on a regular basis, particularly in driftnet vessels, despite the existence since the mid-1990s of national legislation banning the capture of marine mammals and commerce in their products. It is concluded that the coast of Peru is likely still one of the world’s principal areas for concern regarding high small cetacean bycatch and there is clearly an urgent need to increase the geographic scope of observer effort to elucidate the full magnitude of this issue.     

Generation of a Mixolab Profile After the Evaluation of the Functionality of Different Commercial Wheat Flours for Hot‐Press Tortilla Production

Refined wheat flours commercially produced by five different U.S. and Mexican wheat blends intended for tortilla production were tested for quality and then processed into tortillas through the hot‐press forming procedure. Tortilla‐making qualities of the flour samples were evaluated during dough handling, hot pressing, baking, and the first five days on the shelf at room temperature. The predominant variables that affected the flour tortilla performance were wet gluten content, alveograph W (220–303) and P/L (0.70–0.94) parameters, farinograph water absorption (57%) and stability (10.8–18.7 min), starch damage (5.43–6.71%), and size distribution curves (uniform particle distribution). Flours produced from a blend of Dark Northern Spring (80%) and Mexican Rayon (20%) wheat had the highest water absorption, and tortillas obtained from this blend showed the highest diameter and lowest thickness. The whitest and best textured tortillas were obtained from the flour milled from three hard types of Mexican wheat blend. A Mixolab profile was generated from the best tortilla flours, those produced by mills 3 and 4. The Mixolab profile showed that a good flour for hot‐press tortillas had a relatively lower absorption and short dough mix time compared with a bread flour and should have a significantly higher gluten compared with an all‐purpose flour. Compared with bread flour, the tortilla flour had higher retrogradation and viscosity values. The Mixolab profile proved to be a good preliminary test to evaluate flours for hot‐press tortillas.     

Characterization of an extremely large, ligand-induced conformational change in plasminogen

Native human plasminogen has a radius of gyration of 39 angstroms. Upon occupation of a weak lysine binding site, the radius of gyration increases to 56 angstroms, an extremely large ligand-induced conformational change. There are no intermediate conformational states between the closed and open form. The conformational chang is not accompanied by a change in secondary structure, hence the closed conformation is formed by interaction between domains that is abolished upon conversion to the open form. This reversible change in conformation, in which the shape of the protein changes from that best described by a prolate ellipsoid to a flexible structure best described by a Debye random coil, is physiologically relevant because a weak lysine binding site regulates the activation of plasminogen.     

Quantification and persistence of recombinant DNA of Roundup Ready corn and soybean in rotation

The presence of the recombinant cp4 epsps gene from Roundup Ready (RR) corn and RR soybean was quantified using real-time PCR in soil samples from a field experiment growing RR and conventional corn and soybean in rotation. RR corn and RR soybean cp4 epsps persisted in soil for up to 1 year after seeding. The concentration of recombinant DNA in soil peaked in July and August in RR corn and RR soybean plots, respectively. A small fraction of soil samples from plots seeded with conventional crops contained recombinant DNA, suggesting transgene dispersal by means of natural process or agricultural practices. This research will aid in the understanding of the persistence of recombinant DNA in agricultural cropping systems.     

宜黄自然保护区华南虎野生种群调查及栖息地评价

江西省宜黄县省级自然保护区以华南虎 (Pantheratigrisamoyensis)为主要保护对象 ,是近几年发现华南虎证据最多的区域 .中美华南虎联合考察队于 2 0 0 1年 3 7月对该保护区进行了调查 ,采用访问调查法、样线调查法、痕迹调查法、红外线自动照相技术等目前国际国内通用的方法和技术 .该次考察虽未证实该区域华南虎存在的确切信息 ,但较系统地调查了该区域的生境资料 ,初步评价了华南虎的生存环境 .其结论为 ,由于乱捕滥猎、过度的经济活动、栖息地缩小和破碎化是导致目前华南虎极度濒危甚至难觅其踪迹的主要原因 .该区域历史上是华南虎较多的区域 ,目前仍具备华南虎生存的基本条件 .     

Effect of glyphosate on the tripartite symbiosis formed by Glomus intraradices,Bradyrhizobium japonicum,and genetically modified soybean

Most soybeans grown in North America are genetically modified (GM) to tolerate applications of the broad-spectrum herbicide glyphosate; as a result, glyphosate is now extensively used in soybean cropping systems. Soybean roots form both arbuscular mycorrhizal (AM) and rhizobial symbioses. In addition to individually improving host plant fitness, these symbioses also interact to influence the functioning of each symbiosis, thereby establishing a tripartite symbiosis. The objectives of this study were to (1) estimate the effects of glyphosate on the establishment and functioning of AM and rhizobial symbioses with GM soybean, and (2) to estimate the interdependence of the symbioses in determining the response of each symbiosis to glyphosate. These objectives were addressed in two experiments; the first investigated the importance of the timing of glyphosate application in determining the responses of the symbionts and the second varied the rate of glyphosate application. Glyphosate applied at recommended field rates had no effect on Glomus intraradices or Bradyrhizobium japonicum colonization of soybean roots, or on soybean foliar tissue [P]. N₂-fixation was greater for glyphosate-treated soybean plants than for untreated-plants in both experiments, but only when glyphosate was applied at the first trifoliate soybean growth stage. These data deviate from previous studies estimating the effect of glyphosate on the rhizobial symbiosis, some of which observed negative effects on rhizobial colonization and/or N₂-fixation. We did observe evidence of the response of one symbiont (stimulation of N₂-fixation following glyphosate) being dependent on co-inoculation with the other; however, this interactive response appeared to be contextually dependent as it was not consistent between experiments. Future research needs to consider the role of environmental factors and other biota when evaluating rhizobial responses to herbicide applications.