High‐density genetic map of Miscanthus sinensis reveals inheritance of zebra stripe

Miscanthus is a perennial C₄ grass that has recently become an important bioenergy crop. The efficiency of breeding improved Miscanthus biomass cultivars could be greatly increased by marker‐assisted selection. Thus, a high‐density genetic map is critical to Miscanthus improvement. In this study, a mapping population of 261 F₁ progeny was developed from a cross between two diploid M. sinensis cultivars, ‘Strictus’ and ‘Kaskade’. High‐density genetic maps for the two parents were produced with 3044 newly developed single nucleotide polymorphisms (SNPs) obtained from restriction site‐associated DNA sequencing, and 138 previously mapped GoldenGate SNPs. The female parent (‘Strictus’) map spanned 1599 cM, with 1989 SNPs on 19 linkage groups, and an average intermarker spacing of 0.8 cM. The length of the male parent (‘Kaskade’) map was 1612 cM, with 1821 SNPs, and an average intermarker spacing of 0.9 cM. The utility of the map was confirmed by locating quantitative trait loci (QTL) for the zebra‐striped trait, which was segregating in this population. Three QTL for zebra‐striped presence/absence (zb1, zb2 on LG 7, and zb3 on LG 10) and three for zebra‐striped intensity (zbi1, zbi2, zbi3 on LGs 7, 10, 3) were identified. Each allele that caused striping was recessive. Incomplete penetrance was observed for each zb QTL, but penetrance was greatest when two or more zb QTL were homozygous for the causative alleles. Similarly, the intensity of striping was greatest when two or more zbi QTL were homozygous for alleles that conferred the trait. Comparative mapping indicated putative correspondence between zb3 and/or zbi2 on LG 10 to previously sequenced genes conferring zebra stripe in maize and rice. These results demonstrate that the new map is useful for identifying marker–trait associations. The mapped markers will become a valuable community resource, facilitating comparisons among studies and the breeding of Miscanthus.     

Iris pigmentation as a quantitative trait: variation in populations of European,East Asian and South Asian ancestry and association with candidate gene polymorphisms

In this study, we present a new quantitative method to measure iris colour based on high‐resolution photographs. We applied this method to analyse iris colour variation in a sample of individuals of East Asian, European and South Asian ancestry. We show that measuring iris colour using the coordinates of the CIELAB colour space uncovers a significant amount of variation that is not captured using conventional categorical classifications, such as ‘brown’, ‘blue’ or ‘green’. We tested the association of a selected panel of polymorphisms with iris colour in each population group. Six markers showed significant associations with iris colour in the European sample, three in the South Asian sample and two in the East Asian sample. We also observed that the marker HERC2 rs12913832, which is the main determinant of ‘blue’ versus ‘brown’ iris colour in European populations, is also significantly associated with central heterochromia in the European sample.     

2012–2013年中国禾柄锈菌小麦专化型小种动态及新毒力谱分析

监测具有潜在威胁的小麦秆锈病病原菌小种动态并分析其毒力谱变化,是培育抗病品种不可或缺的基础工作。在小麦秆锈病鲜有发生的情况下,于2012–2013年获得小麦田间秆锈病标样11份和经有性生殖过程的禾柄锈菌小麦专化型菌样22份。上述菌样经过分离、纯化,得到了53个单孢子堆菌株。利用国内最新采用的禾柄锈菌小麦专化型小种与毒力鉴别寄主体系进行分析,鉴定出13个生理小种,其中34C3RTGQM和34Oro II-MRGQM为优势小种,出现频率均为13.2%,首次发现了对Sr5+Sr11具有联合毒力的6个新小种,其出现频率处在1.9%–13.2%范围内。同时测定出Sr9e、Sr26、Sr31、Sr33、Sr37、Sr38、Sr47和Sr Tt3等8个抗秆锈病单基因对全部供试菌株表现抗病,余下40个单基因系则分别表现对1个以上至全部菌株感病。结论:(1)首次报道了6个对Sr5+Sr11具有危险性的联合毒力谱的新小种类型,这类毒力类型应当被密切关注;(2)明确了当前完全有效的8个抗秆锈病基因和其他部分有效的抗病基因;(3)初步说明了有性循环菌株与无性循环菌株在毒力结构上存在差异。     

Green leaf volatiles enhance aggregation pheromone of boll weevil, Anthonomus grandis

Enhancement of an insect pheromone response by green leaf volatiles is reported for the first time in the boll weevil, Anthonomus grandis Boh. (Coleoptera: Curculionidae). Single cell recordings from antennal olfactory receptors revealed a class of cells selectively responsive to six carbon alcohols and aldehydes (i.e., green leaf volatiles). Field tests with released weevils demonstrated enhanced trap captures with trans-2-hexen-l-ol, cis-3-hexen-l-ol, or l-hexanol paired with grandlure, the boll weevil aggregation pheromone, when in competition with grandlure alone. Although dose-response curves constructed from electroantennograms were indicative of similar populations of receptor cells for selected six carbon alcohols, one of the compounds tested, cis-2-hexen-l-ol, was inactive in field tests. Trans-2-hexenal was active in single cell recordings, but was also inactive in field tests. In tests in cotton fields with indigenous weevil populations, trans-2-hexen-l-ol not only enhanced pheromone trap captures, but also extended the longevity of attractiveness of pheromone-baited traps. The combined electrophysiological and field data support across-fiber coding of green leaf volatiles by boll weevil olfactory receptors. The results are discussed with regard to the chemistry of the host plant of the boll weevil, cotton (Gossypium hirsutum L.), and potential economic significance for boll weevil eradication/suppression.

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Résumé Pour la première fois, l'augmentation de la puissance de la phéromone d'agrégation sous l'action de l'odeur verte est signalée chez A. grandis. Les enregistrements unitaires de cellules des récepteurs olfactifs des antennes a mis en évidence une catégorie de cellules réagissant sélectivement aux alcools et aux aldéhydes à 6 carbones (c'est-à-dire aux substances volatiles des feuilles vertes). Des essais dans la nature ont montré une augmentation des captures par les pièges de grandlure (phéromone d'agrégation du charançon) renforcés par du trans-2-hexen-l-ol, du cis-3-hexen-l-ol, ou du l-hexanol.Bien que les courbes des réponses en fonction des doses construites à partir des électroantennogrammes indiquent des catégories de cellules réceptrices identiques pour les alcools à 6 carbones examinés, l'une de ces substances, cis-2-hexen-l-ol, s'est révélée inactive dans la nature. Le trans-2-hexenal qui était actif avec des enregistrements unitaires de cellules, était lui aussi inactif dans la nature. Dans des essais dans des champs de coton avec des populations indigènes de charançons, le trans-2-hexen-l-ol a, non seulement augmenté l'efficacité des pièges à phéromone, mais a prolongé leur attractivité. Les résultats d'électrophysiologie combinés aux données de la nature appuient le modelage transversal des substances vertes volatiles des feuilles par les récepteurs olfactifs du charançon. Ces résultats sont interprétés en relation avec la chimie de la plante-hôte de A. grandis, le coton, Gossypium hirsutum L., et leur possibilité d'utilisation économique pour l'éradication du charançon.

     

Single cell recordings reveal hydroxydanaidal as the volatile compound attracting insects to pyrrolizidine alkaloids

Employment of electrophysiology in combination with simple chemical techniques elucidated the volatile which permit the localization of sources of pyrrolizidine alkaloids (PAs) by insects exploiting these secondary plant metabolites.Single cell recordings in Rhodogastria moths (Arctiidae) revealed a physiologically clearly separable type of antennal sensilla basiconica (SB II) which responds to headspace air of certain PAs (e.g. monocrotaline), but not to a great variety of odorants. However, stimulus sources of 1 g were required to elicit responses and the maximum frequency (obtained with stimulus sources of 5 mg) was only 50 imps/s. This suggested the occurrence of small amounts of airborne PA degradation products.Extraction and hydrolysis experiments in combination with thin-layer chromatography and using the sensory responses of antennal receptor cells as biological detectors eventually demonstrated that the dihydropyrrolizine hydroxydanaidal emanates in small amounts from sources of those PAs which contain retronecine and heliotridine, respectively, as necine moiety. This substance was also implicated as the volatile mediating attraction of the insects to PA-containing plants, as well as to artificial PA-baits. With respect to the high sensitivity and specificity of SB II-receptor cells to hydroxydanaidal, in particular to its R(-)-enantiomer, they are analogous to the well studied receptor cells for sex-attractant pheromones in Lepidoptera. Similar results were obtained with Danaus (Danainae) and Euchromia (Ctenuchiidae). Initial behavioural tests have proven the attractive power of hydroxydanaidal for PA-insects and thus corroborate our interpretation of the electrophysiological findings.

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Zusammenfassung Elektrophysiologische und einfache chemische Verfahren erlaubten die Eingrenzung und Identifikation des reizwirksamen Prinzips, welches Insekten, die Pyrrolizidin-Alkaloide (PA) nutzen, die Orientierung zu PA-Quellen ermöglicht.Einzelzellableitungen von antennalen Sensilla basiconica bei Rhodogastria (Lepidoptera: Arctiidae) zeigten einen morphologisch nicht unterscheidbaren physiologischen Typ, dessen Rezeptorzellen sich durch eine sehr geringe Spontanaktivität auszeichneten und ausschließlich auf PA-Duft reagierten (SB II). Allerdings wurden (z. B. mit Monocrotalin) Reizquellen-Beladungen von 1 g benötigt, um überschwellige Antworten auszulösen, und die maximal erreichte Aktivität (bei Reizung mit 5 mg) betrug lediglich 50 Imp./s; dies deutete auf das Auftreten von kleinen Mengen eines volatilen Abbauprodukts von PA hin.SB II wurden als biologische Detektoren verwendet, um — kombiniert mit Dünnschichtchromatographie — die Reizwirksamkeit von Produkten von Hydrolyse- und Extraktions-Experimenten mit PA zu testen. Auf diese Weise konnte schließlich gezeigt werden, daß von PA mit Retronecin bzw. Heliotridin als Necin geringe Mengen des Dihydropyrrolizins Hydroxydanaidal (Fig. 1G, H) ausgehen. Synthetisches Hydroxydanaidal stellte sich als der bestwirksame Reiz für SB II-Rezeptorzellen heraus, die bzgl. Spezifität und Sensitivität (insbesondere für R(-)-Hydroxydanaidal) den gut untersuchten Rezeptoren für weibliche Sexualpheromone bei Nachtfaltern vergleichbar sind. Entsprechende Ergebnisse wurden auch mit Danaus (Danainae) und Euchromia (Ctenuchiidae) gewonnen. Erste Verhaltensversuche beweisen die Lockwirkung von Hydroxydanaidal für PA-Insekten und bestätigen die Interpretation der elektrophysiologischen Befunde.

     

Immunohistochemical localization of iodopsin in the retina of the chicken and Japanese quail

Summary Localization of iodopsin in the retina of the chicken and Japanese quail was investigated immunohistochemically with the use of monoclonal antibodies (R1-R4) highly specific for R-photopsin (protein moiety of iodopsin). In paraffin sections of the retina, the outer segments of double cones (principal and accessory cones) and of one particular type of single cones were labeled with the antibodies. In addition, reticular cytoplasmic structures, probably representing the Golgi apparatus in a position close to the vitreous pole of the paraboloid and to the outer limiting membrane were intensely stained in the cone cells bearing an immunoreactive outer segment. In whole-mount preparations, 5 types of cone cells were identified according to the color of oil droplets, i.e., red, yellow, pale-green (principal member of double cones), pale-blue and clear, in addition to a sixth type devoid of an oil droplet (accessory member of double cones). The immunohistochemical analysis of the preparations revealed that R-photopsin (suggesting the presence of iodopsin) is localized in the outer segments of both the principal and accessory members of double cones, and the population of single cones displaying a red oil droplet. Other cones endowed with a yellow, blue or clear oil droplet were not labeled with the antibodies used. Similar results were obtained in the retina of the Japanese quail.     

The fate of large infective doses of Nematodirus battus in young lambs

Mapes C.J., Coop R.L. and Angus K.W. 1973. The fate of large infective doses of Nematodirus battus in young lambs. International Journal for Parasitology3: 339–347. The fate of 300,000 and 5 × 60,000 infective larvae of Nematodirus battus during the 2–3 weeks after patency was studied in 3-month-old lambs. The proportions of the infective doses recovered after 18, 26 and 34 days were 37, 6 and 3.5 per cent in the single dose and 29,12 and 4.7 in the multiple dose groups. Fifth-stage larvae and adults, especially females, were preferentially lost from the hosts. The numbers of worms present and the percentage of fourth-stage larvae present were similar in both the single and multiple dose groups.     

An anion channel of sarcoplasmic reticulum incorporated into planar lipid bilayers: Single-channel behavior and conductance properties

Summary An anion channel of sarcoplasmic reticulum vesicle has been incorporated into planar lipid bilayers by means of a fusion method and its basic properties were investigated. Analysis of fusion processes suggested that one SR vesicle contained approximately one anion channel. The conductance of this channel has several substates and shows a flickering behavior. The occupation probability of each substate was voltage dependent, which induced an inward rectification of macroscopic currents. Further, the anion channel was found to have the following properties. (1) The single-channel conductance is about 200 pS at 100mm Cl^–. (2) The channel does not select among monovalent anions but SO ₄ ^2– hardly permeates through the channel. (3) SO ₄ ^2– added to thecis side (the side to which SR vesicles were added) inhibits Cl^– current competitively in a voltage-dependent manner. (4) An analysis of this voltage dependence suggests that the binding site of SO ₄ ^2– is located at about 36% of the way across the channel from thecis entrance.     

Ion permeation through single channels activated by acetylcholine in denervated toad sartorius skeletal muscle fibers: Effects of alkali cations

Summary The gigaohm seal technique was used to study ion permeation through acetylcholine-activated channels in cell-attached patches of the extrajunctional membrane of chronically denervated, enzyme-treated cells from the sartorius muscle of the toadBufo marinus. The most frequently occurring channel type (>95% of channel openings), provisionally classified as extrajunctional, had a chord conductance of approximately 25 pS under normal conditions (–70 mV, 11°C, Normal Toad Ringer's). The less frequently observed channel type (<5% of channel openings), classified as a junctional type, had a conductance of 35 pS under the same conditions, and a similar null potential. In many patches, a small percentage (usually <2%) of openings of the extrajunctional channel displayed a lower conductance state. The shape of theI–V curves obtained for the extrajunctional channel dependend on the predominant extracellular cation. For Cs and K, theI–V curves were essentially linear over the voltage range +50 to –150 mV across the patch, suggesting that the potential independent component of the energy profile within the channel was symmetrical. For Li, theI–V curve was very nonlinear, displaying a significant sublinearity at hyperpolarized potentials. Both an electrodiffusion and a symmetrical uniform four-barrier, three-site rate-theory model provided reasonable fits to the data, whereas symmetrical two-barrier, single-site rate-theory models did not. For the alkali cations examined, the relative permeability sequence wasP _Cs>P _K>P _Na>P _Li—a proportional selectivity sequence. This was different from the single channel conductance sequence which was found to be _K> _Cs> _Na> _Li implying that ions do not move independently through the channel. The relative binding constant sequence for the channel sites was found to be a polarizability sequence, i.e.,K _Li>K _Cs>K _Na>K _K There was an inverse relationship for the cations examined. Under conditions when the single-channel conductance was relatively high, the conductance at depolarized potentials was lower than that predicted by both electrodiffusion and rate theory models, suggesting that there was a rate-limiting access step for ions, from the intracellular compartment into the channel.     

Mechanism of anion-cation selectivity of amphotericin B channels

Summary Zero current potential and conductance of ionic channels formed by polyene antibiotic amphotericin B in a lipid bilayer were studied in various electrolyte solutions. Nonpermeant magnesium and sulphate ions were used to independently vary the concentration of monovalent anions and cations as well as to maintain the high ionic strength of the two solutions separated by the membrane. Under certain conditions the channels select very strongly for anions over cations. They are permeable to small inorganic anions. However, in the absence of these anions the channels are practically impermeable to any cation. In the presence of a permeant anion the contribution of monovalent cations to channel conductance grows with an increase in the anion concentration. The ratio of cation-to-anion permeability coefficients is independent of the membrane potential and cation concentration, but it does depend linearly on the sum of concentrations of a permeant anion in the two solutions. These results are accounted for on the assumption that a cation can enter only an anion-occupied channel to form an ionic pair at the center of the channel. The cation is also assumed to slip past the anion and then to leave the channel for the opposite solution. This model with only few parameters can quantitatively describe the concentration dependences of conductance and zero current potential under various conditions.