The advantages of using a combination of LDL and glutamine in comparison with TRIS egg yolk and Equex® STAMP extenders in the cryopreservation of canine semen

Twenty semen samples taken from 5 dogs were frozen in liquid nitrogen at ?196 °C in four different extenders: one control extender based on 20% egg yolk, 6% LDL alone (low density lipoproteins: the active cryoprotective principle in chicken egg yolk), 6% LDL combined with 20 mmol glutamine, and Equex® (a reference extender that we wish to compare with the LDL-glutamine combination). After thawing, spermatozoal motility was evaluated using a HAMILTON THORNE CERROS 12 image analyzer; the percentage of motile spermatozoa was 27.7% in the egg yolk extender (p < 0.05), 49.9% with 6% LDL alone (p > 0.05), 54.7% in the 6% LDL + 20 mmol glutamine extender, and 47.9% with Equex® (p > 0.05). The motility parameters (VAP, VCL, VSL and ALH) were also superior in the 6% LDL + 20 mmol glutamine extender in comparison with the other extenders.Finally, the spermatozoa were generally better protected during freezing with the 6% LDL + 20 mmol glutamine association than with the egg yolk, 6% LDL, or Equex extenders in terms of the flagellar plasma membrane (HOS test), DNA (Acridine orange test), and acrosome integrity (Spermac® test: no significant difference). The Equex® extender obtained the best results for the acrosome, followed by 6% LDL + 20 mmol glutamine (FITC-PSA test: p < 0.05 between each extender).     

中国的寄生性杜鹃及其宿主多样性(英文)

通过多年的调查资料、观鸟爱好者所提供的图片和文献整理,我们对多杜鹃寄生系统下的中国寄生性杜鹃及其宿主的多样性进行了系统研究。在中国分布的17种寄生性杜鹃中,迄今已发现11种杜鹃的宿主达55种,均为雀形目鸟类,隶属于15科,其中莺科、鸫科和画眉科分别占到寄生记录总数的 22.6%、20.8% 和 17.0%。大杜鹃(Cuculus canorus)的宿主种类最多(45.5%),是中国最常见、宿主多样性最丰富的寄生性杜鹃。不同种类的寄生性杜鹃的卵色不同,而且杜鹃与其宿主之间均呈现明显的卵色多态性,为典型的卵色协同进化。基于人眼观察,大杜鹃、小杜鹃(C. poliocephalus)和八声杜鹃(Cacomantis merulinus)的卵色均与其宿主高度模拟,而鹰鹃(Cuculus sparverioides)、中杜鹃(C. saturatus)和翠金鹃(Chrysococcyx maculatus)则产非模拟的卵。目前仍有6种寄生性杜鹃的宿主不详,亟待加强研究。     

为什么寄生性繁殖的鸟类产厚壳卵?(英文)

鸟类巢寄生是研究协同进化的模式系统。寄生性繁殖的鸟类进化出非常独特、且相对要厚很多的卵壳。关于厚卵壳的进化,主要有以下假说:1)防止产卵损坏假说,即寄生者在巢上将卵产至宿主的巢中时避免损坏;2)防止宿主啄破假说,即厚卵壳可以有效防止宿主对寄生卵的啄破,使其无法扔掉寄生卵;3)雏鸟生长能量假说,即雏鸟具有排他性,由于其较大的身体肌肉骨骼系统发育需要大量钙质,导致卵壳的钙富集而变得较厚;4)抗菌保护假说,即较厚的卵壳有利于保护寄生者的胚胎免于被宿主巢内的微生物所侵害。本文综述了目前关于寄生性繁殖鸟类的厚卵壳进化机制的研究,认为这些假说之间并非相互排斥,但都缺乏足够的实验证据,尽管防止产卵损坏假说和防止宿主啄破假说得到了较多的支持。对于防止宿主啄破假说,如何去量化宿主对寄生卵的拒绝方式如口吞式扔卵、啄破式扔卵和弃巢等,均直接影响到该假说的检验。对此,我们给出了具体的研究建议。     

Elemental compositions of comet 81P/Wild 2 samples collected by Stardust

We measured the elemental compositions of material from 23 particles in aerogel and from residue in seven craters in aluminum foil that was collected during passage of the Stardust spacecraft through the coma of comet 81P/Wild 2. These particles are chemically heterogeneous at the largest size scale analyzed ( approximately 180 ng). The mean elemental composition of this Wild 2 material is consistent with the CI meteorite composition, which is thought to represent the bulk composition of the solar system, for the elements Mg, Si, Mn, Fe, and Ni to 35%, and for Ca and Ti to 60%. The elements Cu, Zn, and Ga appear enriched in this Wild 2 material, which suggests that the CI meteorites may not represent the solar system composition for these moderately volatile minor elements.     

Reservoirs' siltation measurments and sediment transport assessment in the Czech Republic, the Vrchlice catchment study

Sediment transport from agricultural land into rivers and reservoirs is a problem within the Czech Republic. This problem was highly accelerated almost 50 years ago during the communist period. At that time strong collectivization was undertaken leading to destruction of traditional landscape patterns, surface outflow, erosion processes intensification and surface water quality deterioration. Thirteen years after political changes erosion problems remain.At the Department of Irrigation, Drainage and Landscape Engineering at the CTU Prague there has been continuous research undertaken in the field of erosion and sediment transport assessment. There are several modelling tools available for this purpose. One of them—USLE (Universal Soil Loss Equation) is commonly used in the Czech Republic for many years at a plot-scale but modern GIS (geographical information systems) tools in computer science allow using it at larger scales. Very important is the validation of this model for two-dimensional topography and GIS routines. Moreover USLE produces only local erosion amount values and has to be completed by another tool to get sediment amounts. For this purpose SDR (sediment delivery ratio) is usually used, applying a lumped approach—total erosion of every watershed is reduced by SDR and by pond’s trapping efficiency. Another available approach is using the Watem/SEDEM model that puts together RUSLE (Revised USLE) and a distributive approach to sediment transport modelling. This has already been used for estimating sediment amount in several catchments of the Czech Republic, but has to be validated as well.At the Dept. of Drainage, Irrigation and Landscape Engineering there are datasets of sediment amount from different reservoirs available and other reservoirs are to be measured soon. As the dataset of various watersheds is expanded, a methodology for sediment amount measurements is needed. The main objective of this paper is to propose a simple methodology to measure the sediment amount within reservoirs as well as to present a review of available methods. The application of the methodology at Vrchlice Catchments (97 km²) case study is presented. Total sediment amounts between 125 000140 000 m³ were measured in Vrchlice reservoir and values of 110 976 m³ (using USLE), resp. 105833 m³ (using Watem/SEDEM) were predicted by the erosion models. For catchments of this scale it is a sufficient validation.     

Physicochemical modifications of high-pressure-treated soybean protein isolates

Changes induced by high pressure (HP) treatment (200-600 MPa) on soybean protein isolates (SPI) at pH 3 (SPI3) and pH 8 (SPI8) were analyzed. Changes in protein solubility, surface hydrophobicity (Ho), and free sulfhydryl content (SH(F)) were determined. Protein aggregation and denaturation and changes in secondary structure were also studied. An increase in protein Ho and aggregation, a reduction of free SH, and a partial unfolding of 7S and 11S fractions were observed in HP-treated SPI8. Changes in secondary structure were also detected, which led to a more disordered structure. HP-treated SPI3 was partially denatured and presented insoluble aggregates. A major molecular unfolding, a decrease of thermal stability, and an increase of protein solubility and Ho were also detected. At 400 and 600 MPa, a decrease of the SH(F) and a total denaturation were observed.     

Greenhouse Study on the Effects of the Urease Inhibitors Phenyl Phosphorodiamidate and N-(n-butyl) Thiophosphoric Triamide on the Efficiency of Urea Applied to Flooded Rice

Urea was split applied to transplanted rice in a greenhouse experiment with two-thirds applied as labeled ¹⁵N urea at 15 days after transplanting (DAT) and one-third (not labeled) at 42 DAT to determine the effect of the urease inhibitors phenyl phosphorodiamidate (PPDA) and N-(n-butyl) thiophosphoric triamide (NBPT) on urea hydrolysis, plant uptake, yield, and loss of fertilizer N. An acidifying agent [Al₂(SO₄)₃] and an algicide were used to reduce the floodwater pH and thus slow the degradation of PPDA, keeping it effective for a longer period. Algicide addition extended the effectiveness of PPDA inhibition by about 2 days and increased plant uptake and grain yield significantly over that with urea use alone. Al₂(SO₄)₃ addition extended the effectiveness of PPDA only about 1 day, increased N uptake slightly, but failed to increase grain yield. NBPT effectively slowed urea hydrolysis, more than doubled plant uptake over that with urea alone, and increased grain yield by 38%. Percolation at 0.5 cm per day caused plant N uptake to increase by about 6% in all treatments but it was not essential for the inhibitors to have a beneficial effect. For the first split application, fertilizer losses of 50% from urea were decreased to about 10% by use of NBPT and to 28% with PPDA alone, and by combination of PPDA with the algicide losses were 22%.     

Some rate considerations on COD determinations

The usefulness of rate information coupled to COD determinations is discussed. A multiparameter system is presented which reflects changes in both the quantity and the overall nature of the oxidizable material. The insight gained by utilization of systems such as the one presented here is illustrated with model compounds and a few samples taken from reactor effluents from a sewage plant. The gain in information is believed to be potentially of use in the planning and improvement of treatments for waste waters.     

Interfacial and oil/water emulsions characterization of potato protein isolates

Interfacial and emulsifying properties of potato protein isolate (PPI) have been studied to evaluate its potential application to stabilize oil/water emulsions at two pH values (2 and 8). The amount, type, and solubility of proteins and the size of aggregates have been determined in aqueous dispersion. Air-water and oil-water interfacial properties (adsorption, spreading, and viscoelastic properties) have been determined as a function of concentration and pH using soluble phases of PPI. The behavior of PPI stabilized oil/water emulsions has been then analyzed by droplet size distribution measurements and interfacial concentration. PPI exhibits low solubility over a wide range of pH values, with the presence of submicrometer aggregates. The pH value exerts a negligible effect on interfacial tension (oil-water) or surface pressure (air-water) but displays very important differences in viscoelastic properties of the interfacial films formed between oil and water. In this sense, pH 8 provides a major elastic response at oil-water interfaces as compared to pH 2. In relation with this result, a much higher ability to produce fine and stable emulsions is noticed at pH 8 as compared to pH 2. Consequently, there is an evident relationship between the rheological properties of the oil-water interfacial films and the macroscopic emulsion behavior.