生物降解地膜应用与地膜残留污染防控

地膜是农业生产中重要的生产资料之一,过去30多年,地膜用量和农作物覆膜面积一直稳定增长,2014年地膜用量达到了144万t,覆膜面积超过1 800万hm~2,该技术对保障我国农产品安全供给作出了重大贡献。与此同时,地膜残留污染问题越来越严重,一些农田的地膜残留量超过250 kg/hm~2,在我国西北的局部区域,地膜残留已经对农田土壤、作物生长发育、农事作业等造成严重影响和危害。生物降解地膜成为替代普通PE地膜、解决地膜残留污染的一种有效措施和手段,目前生物降解地膜正处于产品研发和评价试验的关键阶段,部分生物降解地膜产品在马铃薯、花生、烟草生产上显示出良好的效果,但总体上还面临巨大挑战,主要包括需要进一步提高地膜产品质量,提高地膜产品破裂和降解可控性,改善地膜的增温保墒能力,实现满足农作物对地膜覆盖功能的要求;此外,需要降低生物降解地膜综合成本,促进生物降解地膜规模化应用。总体上,随着技术进步和农业生产环境的变化,生物降解地膜应用将具有良好的前景。     

半干旱黄土高原地区春小麦地膜覆盖研究概述

在黄土高原半干旱地区春小麦上进行的地膜覆盖试验表明,地膜覆盖通过改善耕层土壤生态环境条件,即通过改善水,热状况,活化土壤养分,对提高水分和养分利用效率,实现粮食增产具有重要作用,但近年来在生产实践和科学实验中发现,不合理的长期全生育期地膜覆盖,因在作物生长前期和中期覆膜作物较不覆膜作物生长好,覆膜作物在生长期水分蒸腾损失严重,土壤水分的蒸散（蒸发＋蒸腾）损失远比不覆膜土壤严重,在作物生长后期降水少或没有补充灌溉时,会产生严重的水分肋迫现象,显著抑制小穗分化和灌浆,最终导致收获得指数和产量下降,同时,地膜覆盖的增产作用在一定程度上是以耗竭土壤肥力,特别是在有机物质为代 的,因此,不正确的地膜覆盖（如全生育期的地膜覆盖）,不仅有时起不到显著的增产作用,而且易造成土壤养分,特别是土壤中硝态氮的累积和损失,肥料利用效率降低,土壤生态条件恶化,下降,难以持续高产,因此在确定地膜覆盖范式时,必须要考虑底墒,作物生育期降水,地膜覆盖的阶段性和氮肥的施用等。     

The Surgical Isolator

A plastic film isolator has been developed which is intermediate between a half-suit and an arm isolator. Used for orthopaedic surgery in an aseptic environment few operating difficulties have been found, and an extended trial of its use should be carried out to assess its effect on the incidence of postoperative wound infection.     

A novel method for the detection of receptors and membrane proteins by scintillation proximity radioassay

A rapid and convenient binding assay for receptors and membrane proteins has been developed. It is based on the binding of 125I-labeled ligands to membrane proteins adsorbed to polyvinyltoluene plastic scintillation microspheres. Membranes or isolated membrane proteins adsorb to the beads upon mixing, and addition of 125I-labeled ligand induces photon emission which is proportional to the amount of added receptor or membrane protein. The interaction of acetylcholine receptor with 125I-labeled alpha-bungarotoxin and antigens with 125I-labeled antibodies or protein A were used as models to test the system. As little as 1 ng of acetylcholine receptor is detected by the assay and a linear relationship with receptor concentration is observed up to 50 ng of receptor per 250 microliter reaction medium. The effects of detergents, salts, soluble proteins, and neutral membranes were studied. Inclusion of bovine serum albumin up to 1 mg/ml, sodium chloride up to 0.5 M, and membranes up to 10 micrograms/ml cause little or no effect on the assay. Detergents at 10-fold below their critical micelle concentrations had little or no effect on the assay. The pharmacological effects of agonists such as acetylcholine were conveniently studied by following the displacement of the 125I-labeled ligand. Similarly, the amount of toxin in crude snake venom can be assayed by measuring competition with the labeled toxin. Only a few seconds are required to perform each binding assay.     

半干旱雨养区不同覆膜方式对冬小麦土壤水分利用及产量的影响

在黄土高原半干旱雨养条件下,于2008—2009、2009—2010两个年度,以露地种植为对照(CK),研究了不同覆膜方式(全膜覆土穴播,全膜穴播,垄膜沟播)对旱地冬小麦产量和水分利用的影响。结果表明:两年度覆膜平均较CK产量分别显著提高49.4%和53.2%,水分利用效率提高11.8%和14.3%。覆膜的高产建立在高生长量、高耗水基础上,产量与生育期耗水量显著正相关(r=0.952*—0.958*),两年度覆膜分别平均较CK多耗水33.5%和34.1%。覆膜处理中以全膜穴播较CK的增产幅度和WUE提高幅度最大,耗水量也最大。由于覆膜耗水量大,覆膜各处理收获期0—200 cm土壤贮水量均显著低于CK,但通过全年连续覆膜和夏闲期降水补充,在下茬秋播时,覆膜各处理0—200 cm土壤贮水量均超过CK,夏闲期覆膜的水分休闲效率两年度分别平均高出CK 41.8和86.4个百分点,覆膜有利于土壤水分恢复和下茬作物的可持续生产。覆膜方式中,以全膜覆土穴播种植效益最高,两个年度纯收益平均达5531.6元/hm2,较CK增收2542.2元/hm2。综合考虑,全膜覆土穴播是一种高产高效兼顾、操作简单、适宜于半干旱雨养区推广应用的冬小麦覆膜种植方式。     

Development of ACTH-containing cells in the hypothalamus and hypophysis in their normal state and in protein deficiency

In cryostate sections of the brain and hypophysis of newborn, 10- and 21-day-old rats, by means of the indirect method immunohistochemical reaction has been performed. As a primary serum rabbit antiserum against ACTH has been used. The ventromedial hypothalamus and adenohypophysis have been studied by means of light and electron microscopy. Relationship of ACTH-containing cells in the adenohypophysis in the process of the postnatal ontogenesis and protein insufficiency remains constant. Unlike the adenohypophysis, in the hypothalamus part of the ACTH-containing cells decreases with age. When the animals develop under conditions of protein insufficiency, changes in the part of the ACTH-positive cells, that are age-dependent, do not coincide with corresponding parameters in the control. In the adenohypophyseal cells the products of diaminobensidine reaction are distributed in cytoplasm of granules with a dense center 100-200 nm in the diameter. The ACTH-containing cells in the hypothalamus are presented as small neurons with an even distribution of the immunohistochemical reaction products in cytoplasm and in large granules 200-280 nm in the diameter. Since in the adenohypophysis and in the hypothalamus various dynamics on contents of ACTH-reactive cells in the postnatal ontogenesis and at protein insufficiency has been revealed, and various localization of the diaminobenzidine reaction products has been demonstrated, a conclusion is made on heterogenous nature of antigenic determinants against ACTH, situating in these structures.     

Verification of a new biocompatible single‐use film formulation with optimized additive content for multiple bioprocess applications

Single‐use bioprocessing bags and bioreactors gained significant importance in the industry as they offer a number of advantages over traditional stainless steel solutions. However, there is continued concern that the plastic materials might release potentially toxic substances negatively impacting cell growth and product titers, or even compromise drug safety when using single‐use bags for intermediate or drug substance storage. In this study, we have focused on the in vitro detection of potentially cytotoxic leachables originating from the recently developed new polyethylene (PE) multilayer film called S80. This new film was developed to guarantee biocompatibility for multiple bioprocess applications, for example, storage of process fluids, mixing, and cell culture bioreactors. For this purpose, we examined a protein‐free cell culture medium that had been used to extract leachables from freshly gamma‐irradiated sample bags in a standardized cell culture assay. We investigated sample bags from films generated to establish the operating ranges of the film extrusion process. Further, we studied sample bags of different age after gamma‐irradiation and finally, we performed extended media extraction trials at cold room conditions using sample bags. In contrast to a nonoptimized film formulation, our data demonstrate no cytotoxic effect of the S80 polymer film formulation under any of the investigated conditions. The S80 film formulation is based on an optimized PE polymer composition and additive package. Full traceability alongside specifications and controls of all critical raw materials, and process controls of the manufacturing process, that is, film extrusion and gamma‐irradiation, have been established to ensure lot‐to‐lot consistency. © 2014 The Authors. Published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers Biotechnol. Prog., 30:1171–1176, 2014     

Plastic pollution in croplands threatens long‐term food security

Plastic pollution is a global concern given its prevalence in aquatic and terrestrial ecosystems. Studies have been conducted on the distribution and impact of plastic pollution in marine ecosystems, but little is known on terrestrial ecosystems. Plastic mulch has been widely used to increase crop yields worldwide, yet the impact of plastic residues in cropland soils to soil health and crop production in the long term remained unclear. In this paper, using a global meta‐analysis, we found that the use of plastic mulch can indeed increase crop yields on average by 25%–42% in the immediate season due to the increase of soil temperature (+8%) and moisture (+17%). However, the unabated accumulation of film residues in the field negatively impacts its physicochemical properties linked to healthy soil and threatens food production in the long term. It has multiple negative impacts on plant growth including crop yield (at the mean rate of ?3% for every additional 100 kg/ha of film residue), plant height (?2%) and root weight (?5%), and soil properties including soil water evaporation capacity (?2%), soil water infiltration rate (?8%), soil organic matter (?0.8%) and soil available phosphorus (?5%) based on meta‐regression. Using a nationwide field survey of China, the largest user of plastic mulch worldwide, we found that plastic residue accumulation in cropland soils has reached 550,800 tonnes, with an estimated 6%–10% reduction in cotton yield in some polluted sites based on current level of plastic residue content. Immediate actions should be taken to ensure the recovery of plastic film mulch and limit further increase in film residue loading to maintain the sustainability of these croplands.     

地膜降解途径及机理研究进展

我国地膜使用量已占农业塑料薄膜使用量的半数以上,其大规模使用在带来巨大经济价值的同时也造成了“白色污染”,残膜难回收、难降解,直接影响土壤的再生能力。本文综述了我国地膜使用现状及其降解方面的研究进展,分别对地膜降解的生物与非生物途径和机理进行了概括,重点分析了非生物降解途径中光催化、金属离子掺杂等对聚烯烃降解的协同效应,以及生物降解途径中不同来源的菌和酶对聚烯烃降解效率的影响,并展望未来发展出更为高效的地膜降解方式,为后续地膜降解及环境中微塑料的降解研究提供参考。     

黄土旱塬不同覆盖对春玉米产量及土壤环境影响

对黄土旱塬用不同覆盖对春玉米产量及土壤环境影响的研究表明,春玉米采用不同覆盖技术,均有显著的增产效果,能显著增加土壤贮水量,使土壤上层长期保持湿润状态,提高土壤温度(除秸秆覆盖外),降低昼夜温差,避免降雨直接冲击地面。保持良好的土壤结构,渗水地膜覆盖与秸秆覆盖、常规地膜覆盖和不覆盖相比,其产量分别增长6．4％、23．6％和29．1％,水分利用效率分别为21．5、20．2、17．4和16．7kg·mm^-1·hm^-2,秸秆覆盖还能提高土壤有机质,增加土壤肥力渗水地膜和常规地膜具有相同的增温效果,当气温达到35℃以上时,渗水地膜还具有降低极端温度的调节功能,但是,覆盖易造成有机质大量矿化和NO3^--N的淋失。     

Pertussis vaccine as an inducer of suppressor cells inhibiting the local graft versus host reaction

The formation of nonspecific suppressor cells inhibiting the development of the graft versus host (GvH) reaction is shown to occur in the spleen of CBA mice after the injection of pertussis vaccine. 2 splenocyte populations have been found to possess suppressing activity: one of them comprises the splenocytes sensitive to anti-theta serum, carrying no receptors to IgG and IgM on their surface and incapable of adherence to the plastic surface; the splenocytes in the other population adhere to the plastic surface. During incubation and in vitro contact with the allogenic cells of intact donors the suppressor splenocytes release soluble mediators capable of suppressing the GvH reaction.     

Membranotropic action of cardiotonic agents and ubiquinone

Interaction of cardiotonic drugs (strophantidine acetate, suphan, para-oxybenzoic acid) and ubiquinone with phospholipid bilayers has been studied. Exothermic effect of the reaction followed by an increase in microviscosity and hydrophobicity of the bilayer from cardiolipin, but by a decrease of the microviscosity of the bilayer from lecithin has been estimated. A correlation is observed between changes in the lecithin bilayer fluidity and the heat effect of the interaction at the initial period of time after mixing of reagents.     

Control of lipopolysaccharide-high density lipoprotein binding by acute phase protein(s)

When Salmonella minnesota R595 lipopolysaccharide (LPS) is mixed with serum, the LPS eventually forms a complex with high density lipoprotein (HDL). Complex formation is conveniently followed by CsCl equilibrium density gradient centrifugation. When mixing 10 micrograms LPS with normal rabbit serum (NRS) at 37 degrees C in the presence of 20 mM EDTA, the half-life for LPS binding to HDL is typically 2 to 3 min. When the same experiment is performed with the use of acute phase rabbit serum (APRS; collected 24 hr post-induction with silver nitrate), the half-life for LPS binding to HDL is typically 40 to 100 min. Thus LPS binding to HDL occurs some 20- to 40-fold slower in APRS than in NRS. Two other phenomena have been found, the time dependencies of which correlate well with the time dependency of LPS binding to HDL in APRS. If LPS-APRS reaction mixtures are cooled to 4 degrees C shortly after mixing and are dialyzed against 2.5 mM HEPES, 15 mM NaCl, pH 7.4 buffer, LPS is recovered in the washed precipitates ("euglobulin precipitate") if, and only if, the LPS-HDL binding reaction is not complete. The amount of LPS in the precipitate correlates well with the amount of LPS that has not bound to HDL. The second phenomenon we observe is that the LPS-containing euglobulin precipitate prepared from LPS-acute phase serum reaction mixtures shortly after mixing also contains a protein, gp60, the concentration of which in the euglobulin precipitate correlates well with the amount of LPS in the precipitate. Thus three phenomena are kinetically well correlated in APRS: the degree of binding of LPS to HDL, the degree of appearance of LPS in a euglobulin fraction, and the concentration of protein gp60 in the euglobulin fraction. We were unable to precipitate gp60 from APRS in the absence of LPS, from APRS after the LPS has fully bound to HDL, or from normal serum in the presence or absence of LPS. The known properties of gp60 are not reminiscent of any other known acute phase reactant. These data demonstrate that APRS contains acute phase reactants that interact with LPS to modify its buoyant density, its solubility, and the rate of its binding to HDL.     

以生活垃圾堆肥为基质的废弃物铺网草皮建植研究

以生活垃圾堆肥为基质,5种生活废弃物为铺网,对高羊茅、草地早熟禾及本特3种草坪植物的草皮培植与铺坪应用进行了研究.结果表明:(1)在草皮培植中,同种草坪植物在不同铺网草皮中的生长效应差异较大,其中早熟禾在草席与塑料纱网草皮中的综合性能表现较好;本特和高羊茅在竹席和草席中的表现较好.(2)草皮的刈割再生生长能力总体上与草皮培植时的生长状况密切相关,草种与基质、铺网间的协同性存在差异,生长协同性较好的草皮组合为早熟禾的草席草皮、本特的草席与塑料纱网草皮以及高羊茅的草席、纤维网袋与塑料纱网草皮.(3)5种生活废弃物铺网中,塑料薄膜在草皮培植中与各草种间的协同性均最差,其铺网草皮在铺坪应用中的再生生长能力也较差,可见塑料薄膜不适宜作为草皮铺网.     

Interference of serum and serum components with attachment of HeLa 71 cells to the surface of plastic culture vessels

The attachment of HeLa 71 cells to plastic surfaces has been investigated. Without serum in the growth medium the attachment of cells was rapid and not reduced at temperatures down to 25 °C. The cells were not detached by treatment with trypsin-EDTA up to 48 h after incubation. With calf serum in the medium the cells attached equally well to the substrate, but the process was temperature dependent. These cells were detached by trypsin-EDTA treatment. The same results were found when the culture flasks were precoated with serum. The serum coat could be removed by rinsing with potassium bicarbonate at pH 9.7. Preliminary fractionation of the calf serum suggested that the effect was specific.     

Detection of gonadotrophic hormones on isolated thecal interstitial cells of the domestic hen, Gallus domesticus, by an immunohistochemical method

Summary An immunohistochemical method was used to demonstrate the presence of gonadotrophins in isolated ovarian interstitial cells. The cells were obtained by collagenase digestion of large ovarian follicles after removal of the yolk and the granulosa layer. Using a peroxidase-labelled anti-rabbit serum with anti-chicken follicle stimulating hormone (FSH) serum raised in rabbits, a strong positive reaction was obtained. Anti-human FSH serum also produced a positive result but the reaction was weaker. There was no apparent difference in the staining reaction of cells which had been preincubated with ovine FSH serum. Treatment with anti-ovine luteinizing hormone (LH) resulted in a faintly positive reaction.The viability of the cells was tested by the Trypan Blue method and they were identified as steroid-producing cells by the histochemical demonstration of their 3-hydroxysteroid dehydrogenase activity.     

The components of Mycoplasma salivarium and its growth medium that are responsible for film formation.

Studies on film production by mycoplasmas revealed that film was produced by completely disintegrated mycoplasma cells on Noble agar in the presence of horse serum. Film production was due to an enzymic reaction between mycoplasma lipase, possibly phospholipase A, and phospholipid in serum.     

太阳能消毒对温室土壤环境效应及防治黄瓜根结线虫病效果

采用室内测定与大田试验相结合的方法,研究了太阳能不同消毒方式对温室土壤环境的效应及对温室黄瓜根结线虫病的控制效果.结果表明,垄沟式覆盖地膜处理对温室土壤温度、土壤酶的活性、微生物数量的影响最明显,处理16d,棚室10、20、30、40、50cm深土壤的最高温度依次是59.1、57.7、56.6、48.9、47.6℃,平均每天超过55、50、45℃持续时间分别为7.5、8.5h和16h;土壤温度的升高,有利于提高对根结线虫的杀灭效果.0～20cm土壤脲酶、蔗糖酶、碱性磷酸酶、过氧化氢酶分别降低43.3%、18.7%、20.1%和13.1%;土壤真菌、细菌、放线菌数量分别降低96.0%、84.8%、53.9%.垄沟式未覆膜处理对土壤环境的影响次之,平面式未覆膜的影响最小,酶活性降低及土壤微生物数量下降对土壤的活性有一定的负效应.垄沟式覆膜太阳能消毒对温室黄瓜根结线虫控制效果最显著,持效期最长,能有效杀灭温室0～50cm土壤内根结线虫;处理后第1年和第2年对温室黄瓜根结线虫控制效果均达到100%,第3年防效96.7%,第5年仍达72.8%.垄沟式未覆膜控制效果次之;平面式未覆膜控制效果最差,持效期最短.