Resource use efficiency in urban and peri-urban sheep, goat and cattle enterprises

Urban livestock husbandry receives growing attention given the increasing urban demand for livestock products. At the same time, little is known about the resource use efficiency in urban livestock enterprises and eventual negative externalities. In livestock production, feeds are an important resource whose nutrients are transformed into products (meat and milk) to generate financial return to the producer. The lack of knowledge on nutrient supply through feed might lead to oversupply with severe environmental impacts. In Niamey, a typical West African city and capital of the Republic of Niger, urban livestock production is constrained by feed scarcity, especially during the dry season. Here, the issue of resource use efficiency was studied in 13 representative and differently managed sheep/goat and cattle enterprises characterized by high and low feed inputs, respectively, during a period of 28 months. Nitrogen (N), phosphorus (P) and potassium (K) inflows into each farm through livestock feeds and outflows through manure were determined using a semi-structured questionnaire; interviews were accompanied by regular weighing of feed supplied and dung produced. Live weight gain (LWG) and efficiency of conversion of total feed dry matter offered (kg TDMO/kg LWG) were computed along with nutrient balances (NBs) per metabolic body mass (kg0.75). NBs (per kg0.75/day) in the high-input (HI) sheep/goat enterprises were +1762.4 mg N, +127.2 mg P and +1363.5 mg K and were significantly greater (P < 0.05) than those in low-input (LI) units (+69.1 mg N, -98.3 mg P and +16.5 mg K). In HI cattle enterprises, daily balances averaged +454.1 mg N, +40.1 mg P and +341.8 mg K compared to +34.4 mg N, -9.0 mg P and +68.3 mg K (P > 0.05) in LI cattle systems. All systems were characterized by poor conversion efficiencies of offered feed, which ranged from 13.5 to 46.1 kg TDMO/kg LWG in cattle and from 15.7 to 43.4 kg TDMO/kg LWG in sheep/goats. LWG in HI sheep/goats was 53 g/day in the rainy season, 86 g/day in the hot dry season and 104 g/day in the cool dry season, while HI cattle lost 79 g/day in the hot dry season and gained 121 g/day and 92 g/day in the cool dry and rainy seasons, respectively. The data indicate that there is nutrient wasting and scope for improvement of feeding strategies in Niamey's livestock enterprises, which might also decrease nutrient losses to the urban environment.     

Development of a novel fluorometric assay for nitric oxide utilizing sesamol and its application to analysis of nitric oxide‐releasing drugs

Nitric oxide (NO) is related to various physiological effects as well as to numerous diseases caused by accentuation of NO production. Measurement of NO in cells and tissues is difficult as NO readily reacts with other molecules; furthermore, its half‐life as a radical is fleeting. Currently, many NO pharmaceuticals are marketed as therapeutic agents for ischemic disease. Consequently, the identification of NO radicals and determination of generation rate from pharmaceuticals is very important when the effect of the medicinal supply is estimated. In this study, we developed a fluorometric assay for NO employing sesamol (3,4‐methylenedioxyphenol) as a fluorometric substrate. Sesamol is converted to a fluorescent derivative (ex. 365 nm, em. 447 nm), which is dimmer in the presence of NO. The detection limit of NO with this method is 400 fmol; moreover, NO generated from drugs can be measured. Copyright © 2009 John Wiley & Sons, Ltd.     

NIR fluorescent ytterbium compound for in vivo fluorescence molecular imaging

We have developed a new NIR fluorescent probe based on an ytterbium(III) (E)‐1‐(pyridin‐2‐yl‐diazenyl)naphthalen‐2‐ol (PAN) complex. This probe emits near‐infrared luminescence derived from the Yb ion through excitation of the PAN moiety with visible light (λ_ex = 530 nm, λ_em = 975 nm). The results support the possible utility of the probe for in vivo fluorescence molecular imaging. Copyright © 2009 John Wiley & Sons, Ltd.     

荧光标记脂肪酶的固定化及其稳定性

将标记有荧光探针FITC(异硫氰基荧光素)的脂肪酶固定化,通过测定活性和荧光光谱,探究各种因素对固定化后荧光标记脂肪酶性质的影响,并分析活性、构象和荧光光谱三者之间的联系。研究结果表明:在固定化脂肪酶过程中,聚乙二醇400二丙烯酸酯能形成合理的网格结构,使酶活较高;配体诱导酶的催化构象,使酶活性提高到未诱导酶的2倍以上;配体抽提能使脂肪酶活性中心得到释放从而提高催化活力。固定化脂肪酶的稳定性大大提高,在90℃、强酸强碱下固定化酶仍保有原酶70%、60%以上的活性;用盐酸胍、脲等溶解变性剂浸泡15d后,酶活性仍然可以保持初始活性的70%以上。荧光光谱能较好地反映脂肪酶的活性和构象变化,最适pH和温度下脂肪酶的荧光强度最低,在溶解变性剂中,荧光强度随时间延长而逐渐降低,这表明不同条件下脂肪酶构象经历的去折叠过程不同。     

外源褪黑素对小麦幼苗生理及光合荧光特性的影响

为探讨不同浓度外源褪黑素对小麦幼苗生理及光合荧光特性的影响，该研究以良星99为供试材料，测定不同浓度褪黑素处理下小麦幼苗生长形态、光合及荧光参数以及抗氧化酶活性等关键指标。结果表明：(1)0.1μmol·L^-1的褪黑素处理显著提高了小麦植株的光合能力，叶绿素Chl a、Chl b和Chl (a+b)以及叶绿素荧光参数调节性能量耗散的量子产额Y(NPQ)、表观光合传递速率(ETR)和非光化学淬灭(NPQ)均在褪黑素浓度为0.1μmol·L^-1时达到增加最大值；PSⅡ最大光合效率(Fv/Fm)、最大光能转化潜力(Fv/Fo)随褪黑素浓度升高逐渐降低；光化学淬灭(qL)随褪黑素浓度增加先下降后上升。(2)与CK(0μmol·L^-1)相比，低浓度褪黑素显著降低小麦根和叶中过氧化物酶(POD)及小麦叶中过氧化氢酶(CAT)的活性，高浓度褪黑素处理显著增加小麦POD的活性；小麦根中丙二醛(MDA)含量随褪黑素浓度的增加先下降后上升。综上表明，适量褪黑素处理可促进小麦的生长，使小麦光合能力维持在较高水平，并通过POD和CAT调节不同褪...     

Symbiotic streptomycetes in antennal glands of the South American digger wasp genus Trachypus (Hymenoptera,Crabronidae)

Several insect taxa have evolved symbioses with actinobacteria that protect the host or its nutritional resources against pathogens. Digger wasps of the genus Philanthus (‘beewolves’; Hymenoptera, Crabronidae) cultivate ‘Candidatus Streptomyces philanthi’ (Ca. S. philanthi) in specialized antennal glands and transfer them to subterranean brood cells, where the symbionts provide protection for the beewolf larva against pathogens by producing a cocktail of antibiotic substances. The present study investigates the occurrence of antennal symbionts in two species of the genus Trachypus, which is the closest relative to Philanthus. Cross sections of the antennae from females of both Trachypus denticollis and Trachypus boharti reveal bacteria‐containing gland reservoirs that are morphologically very similar to those found in Philanthus spp. Polymerase chain reaction‐based screens with specific primers, sequencing of the partial 16S rRNA gene, and fluorescence in situ hybridization confirm the presence of close relatives of ‘Ca. S. philanthi’ in T. denticollis and T. boharti. However, 16S rRNA sequence divergence between Trachypus spp. and Philanthus spp. symbionts is much higher for T. boharti than for T. denticollis, suggesting that horizontal transmission and/or de novo uptake of symbionts from the environment occurs occasionally. The results obtained indicate that the protective symbiosis with antennal actinobacteria is older and more widespread than previously recognized and occurs in at least two genera of digger wasps that comprise approximately 170 species.     

Subtyping borderline nuclear changes: is it of value in predicting high-grade cervical intraepithelial neoplasia on histology?

The aim was to determine the association between the subtypes of borderline nuclear changes (BNC) in cervical smears and high-grade cervical intraepithelial neoplasia (HCIN). BNC was reported in 23236 smears received in our laboratory over a 7-year period, 3278 patients were referred for colposcopy. Analysis was restricted to 2007 cases, which fitted the criteria of: (1). consistent subtyping of borderline change and (2). cervical histology result within 12 months of the last abnormal smear. BNC was reported in six categories and correlated with histology. Atypia bordering on dyskaryosis, atypical metaplastic cells and endocervical atypia, were associated with HCIN in 25%, 25.4% and 23.8% of cases, respectively. Dyskeratosis and koilocytotic atypia were associated with HCIN in 19.2% and 13.7% of cases, respectively. Some subtypes of borderline change are more frequently associated with HCIN. The difference is not sufficient to dictate clinical management.     

Electrical signals and their physiological significance in plants

Electrical excitability and signalling, frequently associated with rapid responses to environmental stimuli, are well known in some algae and higher plants. The presence of electrical signals, such as action potentials (AP), in both animal and plant cells suggested that plant cells, too, make use of ion channels to transmit information over long distances. In the light of rapid progress in plant biology during the past decade, the assumption that electrical signals do not only trigger rapid leaf movements in 'sensitive' plants such as Mimosa pudica or Dionaea muscipula, but also physiological processes in ordinary plants proved to be correct. Summarizing recent progress in the field of electrical signalling in plants, the present review will focus on the generation and propagation of various electrical signals, their ways of transmission within the plant body and various physiological effects.     

Differential response to paraquat induced oxidative stress in two rice cultivars on antioxidants and chlorophyll a fluorescence

The responses of antioxidative system and photosystem II photochemistry of rice (Oryza sativa L.) to paraquat induced oxidative stress were investigated in a chilling-tolerant cultivar Xiangnuo no. 1, and a chilling-susceptible cultivar, IR-50. Electrolyte leakage and malondialdehyde (MDA) content of Xiangnuo no. 1 were little affected by paraquat, but they increased in IR-50. After paraquat treatment, superoxide dismutase (SOD) activity remained high in Xiangnuo no. 1, while it declined in IR-50. Activities of catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR) declined with oxidative stress in both cultivars, but Xiangnuo no. 1 had higher GR activity than IR-50. Under paraquat induced oxidative stress, ascorbic acid (AsA) and reduced glutathione (GSH) concentrations remained high in Xiangnuo no. 1, but decreased in IR-50. The results indicated that higher activities of SOD and GR and higher contents of AsA and GSH in Xiangnuo no. 1 under paraquat induced oxidative stress were associated with its tolerance to paraquat, while paraquat induced damage to IR-50 was related to decreased activities of SOD, APX and GR and contents of AsA and GSH. F _v/F _m, Φ _PSII, and qP remained high in Xiangnuo no. 1, while they decreased greatly in IR-50 under paraquat induced oxidative stress.     

Trapping of the quenched conformation associated with non-photochemical quenching of chlorophyll fluorescence at low temperature

The kinetics of non-photochemical quenching (NPQ) of chlorophyll fluorescence was studied in pea leaves at different temperatures between 5 and 25°C and during rapid jumps of the leaf temperature. At 5°C, NPQ relaxed very slowly in the dark and was sustained for up to 30 min. This was independent of the temperature at which quenching was induced. Upon raising the temperature to 25°C, the quenched state relaxed within 1 min, characteristic for qE, the energy-dependent component of NPQ. Measurements of the membrane permeability (ΔA₅₁₅) in dark-adapted and preilluminated leaves and NPQ in the presence of dithiothreitol strongly suggest that the effect of low temperature on NPQ was not because of limitation by the lumenal pH or the de-epoxidation state of the xanthophylls. These data are consistent with the notion that the transition from the quenched to the unquenched state and vice versa involves a structural reorganization in the photosynthetic apparatus. An eight-state reaction scheme for NPQ is proposed, extending the model of Horton and co-workers (FEBS Lett 579:4201–4206, 2005), and a hypothesis is put forward concerning the nature of conformational changes associated with qE. Electronic supplementary material The online version of this article (doi: ) contains supplementary material, which is available to authorized users.