Photosynthesis is Reduced,and Seeds Fail to Set and Fill at Similar Soil Water Contents in Grass Pea (Lathyrus sativus L.) Subjected to Terminal Drought

Grass pea (Lathyrus sativus L.) is an indeterminate grain legume considered adapted to dry environments, but the mechanisms of its adaptation are not well understood. Grass pea plants were exposed to terminal drought from podding, and the development of water deficit was measured together with its effects on leaf photosynthesis, stomatal conductance, carbon remobilisation to the seeds, flower production and abortion, pod production and abortion, seed set, seed growth and the neurotoxin β‐N‐oxalyl‐L‐a, β‐diaminopropionic acid (β‐ODAP) concentration. Predawn leaf water potential (Ψ_leaf), stomatal conductance (gs), rate of leaf photosynthesis (Pn), flower production, pod production, filled pod number, seed number, seed size and yield decreased, while flower abortion, pod abortion and seed abortion increased, and the concentration of β‐ODAP was unchanged under terminal drought conditions. gs and Pn began to decrease at a higher plant‐available soil water content (PAWC) (67.2 ± 2.3 % and 62.9 ± 2.3 %) than Ψ_leaf (43.7 ± 1.1 %). Flowers and pods ceased being produced only when the PAWC decreased below 40.1 ± 4.6 % and 35.3 ± 3.0 %, respectively, but seed set and seed growth ceased when PAWC decreased below 55.5 ± 1.6 % and 58.0 ± 3.7 %, respectively. The mobilization of ¹³C labelled assimilates from the stems was greater under terminal drought than under well‐watered conditions, but the transfer to the seed was small. We conclude that seed set and seed growth decreased as the soil dried due to a reduction in current photosynthesis as a result of stomatal closure.     

斑点免疫金渗滤法诊断猪蛔虫病

[目的]探讨斑点免疫金渗滤法诊断猪蛔虫病的可行性,为制备诊断猪蛔虫病试剂盒提供参考依据。[方法]采用猪蛔虫的重组蛋白AS16抗原和胶体金标记葡萄球菌蛋白A（SPA）,根据免疫渗滤原理,建立抗猪蛔虫抗体的斑点金免疫渗滤检测法。[结果]斑点免疫金渗滤法检测1200份猪血清样本中猪蛔虫抗体,检出阳性率为25.00%,而琼脂扩散试验（AGP）阳性检出率为15.00%。[结论]斑点金免疫渗滤检测法具有操作简便,灵敏度高,特异性强的优点,可用于猪蛔虫病的快速检测。     

免疫金标记技术在植物蛋白质亚细胞定位中的应用

在综述免疫金标记技术在蛋白质亚细胞定位中的应用的基础上,就其意义、方法及优缺点等予以探讨。     

The determination of ‘L’ values by discrete and integrated sampling procedures

Abstract

A discrete and an integrated sampling procedure were used to determine ‘ L ‘ values for maize plants grown in a soil. In the discrete procedure a plant was grown in a sand culture labelled with ³³P solution and then transferred in a soil which was labelled with ³²P. In the integrated sampling procedure plants were grown entirely in a P label led soil.

The discrete procedure permits point of time observation so that changes in the equilibrium between solution and surface P and mineralization rates can be monitored.     

Availability of N from Casuarina residues and inorganic N to maize, using 15N isotope techniques

 The contribution of N from Casuarina equisetifolia (casuarina) residues to maize with inorganic N (ammonium sulphate) supplementation was studied in a pot experiment using ¹⁵N labelling techniques. A single rate of N application of 100 mg N kg^–1 soil was applied as N-ammonium sulphate in combination with casuarina residues in the proportions 100 : 0; 75 : 25; 50 : 50; 25 : 75 and 0 : 100, respectively. The directly ¹⁵N-labelled casuarina residue and indirect labelling (unlabelled casuarina + ¹⁵N soil) were compared to estimate the proportion and amount of N derived from the residue and fertilizer. The application of ammonium sulphate at a high rate significantly affected shoot dry matter (P<0.05) and likewise reduced the contribution of soil-derived N compared to residues. Total recoveries by maize of residue N and applied fertilizer N averaged 11% and 24%, respectively. Residue and fertilizer use efficiencies were not influenced by the addition of different rates of fertilizer or residue. The estimation of the contribution of N from different sources showed that direct measurement of the ¹⁵N-labelled organic source was more reliable. Received: 10 September 1997     

CYP1A1 immunolocalization in the olfactory organ of rainbow trout and its possible induction by β-naphthoflavone: analysis in adults and embryos around hatching

Cytochrome P4501A1 (CYP1A1) isoform, which is known as being of major toxicological significance, has been well-studied in the mammalian olfactory mucosa. Only few studies have dealt with this biotransformation system in the fish olfactory organ which is particularly vulnerable to waterborne xenobiotics since sensory neurons are in direct contact with the aquatic environment. The present immunocytochemical study describes the cellular and subcellular distributions of CYP1A1 in the olfactory organ of rainbow trout in both adults and embryos around hatching. The enzyme inducibility in response to a 4-day exposure to waterborne -naphthoflavone (0.1 mg l^–1), a model inducer of CYP1A1, was also examined. In untreated adult fish, CYP1A1 was almost exclusively expressed in the nonsensory epithelium which covers the edges and the tip of the lamellae. Both goblet and ciliated nonsensory cells appeared immunoreactive. In -naphthoflavone-treated fish, in addition to a strong labeling in the nonsensory epithelium, ciliated nonsensory cells in the olfactory epithelium appeared well-labeled. Four days before hatching, only a few cells were weakly stained in the placodal epithelium of some embryos. By 7 days post-hatching, the enzyme expression was increased in the olfactory pit and it was restricted to ciliated nonsensory cells. No evident CYP1A1 induction was detected in either embryos or alevins. Results suggest the presence of a two-line CYP1A1 biotransformation system in the adult fish olfactory organ: a basal level of enzyme expression insured by the nonsensory epithelium and an additional line in which the sensory epithelium is activated in response to CYP1A1 inducers. This system might take place during development in parallel with the onset of the nonsensory epithelium.     

Colonisation tactics of three temperate catadromous species,eel Anguilla anguilla,mullet Liza ramada and flounder Plathychtys flesus,revealed by Bayesian multielemental otolith microchemistry approach

Daverat F, Martin J, Fablet R, Pécheyran C. Colonisation tactics of three temperate catadromous species, eel Anguilla anguilla, mullet Liza ramada and flounder Plathychtys flesus, revealed by Bayesian multielemental otolith microchemistry approach.
Ecology of Freshwater Fish 2011: 20: 42–51. © 2010 John Wiley & Sons A/S Abstract – The colonisation of Gironde (SW France) river catchment by juvenile, eel, Anguilla anguilla, flounder Platychtys flesus and thinlipp mullet Liza ramada was investigated comparatively using Sr:Ca and Ba:Ca composition of otolith. The relation between Sr, Ba and habitat was investigated based on Sr and Ba water composition sampled each month along the estuary‐river gradient. A total of 50 mullets, 30 eels and 47 flounders were collected in the Gironde river catchment. Analysis was performed with a Femtosecond LA‐ICPMS along a trajectory from the core to the edge. Sr and Ba water concentrations discriminated three habitats within the Gironde system, the lower estuary, the upper estuary and the freshwater sites. A signal processing method based on Gaussian hidden Markov models was applied to the multielemental life‐history data. The linear model used to allocate a Gironde habitat to coupled Sr, Ca values was parameterised with seasonal patterns and magnitude of Sr and Ba water values in the different habitats. The results showed that the three species used three different habitats and they had a large diversity of habitat use patterns with resident and nomadic tactics. Resident tactics were less frequent than nomadic tactics that suggested individual fish used two or more habitats. Mullet used a wider range of habitats in the lower part of the estuary than eel and flounder and switched habitats more frequently. Flounders tended to colonise initially freshwater, and then estuarine habitats later in life while mullets used the entire range of available catchment habitats throughout their life.     

Luminal uptake of Vibrio (Listonella) anguillarum by shed enterocytes – a novel early defence strategy in larval fish

As adhesion and translocation through fish gut enterocytes of the pathogen Vibrio (Listonella) anguillarum are not well investigated, the effective cause of disease and mortality outbreaks in larval sea bass, Dicentrarchus labrax, suffering from vibriosis is unknown. We detected V. anguillarum within the gut of experimentally infected gnotobiotic sea bass larvae using transmission electron microscopy and immunogold labelling. Intact bacteria were observed in close contact with the apical brush border in the gut lumen. Enterocytes contained lysosomes positive for protein A‐gold particles suggesting intracellular elimination of bacterial fragments. Shed intestinal cells were regularly visualized in the gut lumen in late stages of exposure. Some of the luminal cells showed invagination and putative engulfment of bacterial structures by pseudopod‐like formations. The engulfed structures were positive for protein A‐colloidal gold indicating that these structures were V. anguillarum. Immunogold positive thread‐like structures secreted by V. anguillarum suggested the presence of outer membrane vesicles (MVs) hypothesizing that MVs are potent transporters of active virulence factors to sea bass gut cells suggestive for a substantial role in biofilm formation and pathogenesis. We put forward the hypothesis that MVs are important in the pathogenesis of V. anguillarum in sea bass larvae.     

番茄斑萎病毒运动蛋白NSm的原核表达及抗体制备

 将番茄斑萎病毒(Tomato spotted wilt virus,TSWV)运动蛋白NSm基因克隆到原核表达载体pET-32a (+) 中,利用大肠杆菌系统表达NSm蛋白,以Ni^2＋-NTA agarose亲和柱纯化该蛋白与His组氨酸的融合蛋白,免疫家兔制备融合蛋白多克隆抗体。Western blot检测显示,该抗体与NSm重组蛋白以及普通烟病叶中的NSm蛋白具有特异性反应。采用该抗体对TSWV感染的普通烟叶片低温超薄切片进行免疫胶体金标记,透射电镜观察发现特异性金颗粒主要定位在病叶细胞的胞间连丝中,而健康烟草叶片组织中没有金颗粒特异性标记。结果表明,该抗体可用于研究NSm在细胞中的定位。     

Demonstration of putative membrane and cytosol steroid receptors for 17α, 20β-dihydroxy-4-pregnen-3-one in brook troutSalvelinus fontinalis oocytes by photoaffinity labelling using synthetic progestin 17,21-dimethyl-19-nor-pregn-4,9-diene-3,20-dione (R5020)

Cytosol from brook trout ovarian follicles (stages 1–3) was photoaffinity (PA) labelled using synthetic progestin 17,21-dimethyl-19-nor-pregn-4,9-diene-3,20-dione ([³H]R5020). The covalently bound cytosol protein had a relative mass of 501,000 M_r following Sephacryl S-300 column chromatography. The zona radiata membrane fraction from brook trout oocytes which had gone through the first phase of meiotic maturation (stages 6–7) was isolated by ultracentrifugation of the whole oocytes. The zona radiata solubilized protein presumably from the oocyte membrane was also PA labelled and found to give a peak at 355,000 M_r. The SDS PAGE of the cytosol and zona radiata PA labelled protein gave very similar subunits indicating that the membrane protein and the cytosol protein, both of which bind the maturation inducing steroid (MIS) 17,20-dihydroxy-4-pregnen-3-one (17,20-DHP), have similar subunit structures. The isolated zona radiata protein showed cooperativity of binding to [³H]17,20-DHP and PA labelling to [³H]R5020. The association constant (K_a) was 2.0×10⁷M^–1 and maximum binding capacity (N_max) 427 fmoles/mg protein with MIS [³H]17,20-DHP.No evidence for nuclear binding of MIS [³H]17,20-DHP or PA labelling of [³H]R5020 to nuclei was observed. The nuclei were isolated from stages 1 and 3 fresh ovarian follicles of brook trout. The experimental evidence presented demonstrates the presence of MIS 17,20-DHP receptor-like protein from the zona radiata membranes by PA labelling in brook trout oocytes during final stages of maturation.