Patterns and Management of Crop Multiple Pathosystems

The study of multiple pathosystems has played a central role in the development of botanical epidemiology, leading to a number of approaches and concepts. Multiple pathosystems are facts, which are experienced by many non-cultivated, or cultivated, plant communities. The shapes and composition of multiple pathosystems vary in space and time because of their inherent structure of relationships, and also in response to management. Examples of variation in multiple pathosystems are given, of groundnut in Côte d’Ivoire, of wheat in Brittany, and of upland rice in northern Laos. Variation in the yield-reducing effects of multiple pathosystems is discussed, including interactions among disease elements, relationships with attainable performances, and linkages with production situations. Progress has been achieved in understanding the links between injury profiles, production situations, and attainable performances. Questions about the functioning and consequences of multiple pathosystems are central to defining the scientific bases for, the design of, and the implementing of IPM. The complexity of multiple pathosystems, however, remains a deterrent, not a challenge, to many plant pathologists. Progress achieved in designing production systems for hardy wheat in France, however, is very promising, because of the multidisciplinary science it involves, and because of the promise to deliver it carries. The concepts of epidemiological guilds and of guilds of harmful agents are offered as perspectives to address and manage syndromes of production and syndromes of disease.     

Comparing the performance of cereal varieties in organic and non-organic cropping systems in different European countries

Top ranking varieties are tested in multiple environments before and after registration in order to assess their value for cultivation and use (VCU testing). Recently, interest has increased in obtaining varieties specifically adapted to organic farming conditions. This raised the question if an independent system of trials may be required for this purpose. To help answering this question, through the exchange network of European cereal researchers SUSVAR (), a number of data sets of agronomic traits from barley, wheat and winter triticale, from trials performed in Denmark, Sweden, The Netherlands, France, Switzerland, UK and Germany, were made available and analysed using an approach based on mixed models involving parameters describing genetic correlation between the two types of experiments, i.e., organic and non-organic (high or low input). Estimated variance components and correlations were used to evaluate response to selection and index selection. The response to index selection was analysed as a function of the fraction of available trials assigned to the organic system. The genetic correlations were interpreted in terms of ranking agreement. We found high genetic correlations between both systems for most traits in all countries. Despite high genetic correlations, the chances of very good agreement in observed rankings were moderate. Combining information from both organic and non-organic systems is shown to be beneficial. Further, ignoring information from non-organic trials when making decisions regarding performance under organic conditions is a sub-optimal strategy.     

微量Bradford法测定提纯禽结核菌素蛋白含量

研究用96孔微量板Bradford法测定提纯禽结核菌素蛋白含量。通过不同浓度的待测禽结核菌素与考马斯亮蓝G-250溶液混合后，在595nm光波下测定各孔样品的OD值。微量Bradford法检测禽结核菌素的线性范围是50—1000μg／mL，相关系数为0．999，最低定量限为50μg／mL。试验用3支禽结核菌素国际参照品，分别配制成125、250、500μg／mL三种不同浓度，每支每种浓度测定4次，计算实际测得的蛋白质浓度。结果显示，批内相对标准偏差为1．6％～4．4％；批间相对标准偏差0．7％-2．2％。研究结果表明微量Bradford法可作为测定禽结核菌素蛋白含量的一种方法。     

Effect of Fall Application of Fungal Antagonists on Spring Ascospore Production of the Apple Scab Pathogen, Venturia inaequalis

ABSTRACT The influences of Microsphaeropsis sp., M. arundinis, Ophiostoma sp., Diplodia sp., and Trichoderma sp., all antagonists of Venturia inaequalis, on ascospore production were evaluated under natural conditions and compared with urea and Athelia bombacina, a known antagonist. In the autumn, the fungi were applied to leaf disks artificially inoculated with V. inaequalis and to scabbed apple (Malus domestica) leaves incubated under controlled and natural conditions. In addition, large-scale trials were conducted with Microsphaeropsis sp. applied either as a foliar postharvest spray or as a ground application at 90% leaf fall. All fungal isolates, except Ophiostoma sp., were recovered from the leaf material that overwintered in the orchard. All treatments, except those with Ophiostoma sp., resulted in a significant reduction in V. inaequalis ascospore production on the leaf disks incubated under controlled conditions or in the orchard. In 1997, leaves with apple scab lesions treated with urea or Microsphaeropsis sp. produced significantly fewer ascospores of V. inaequalis than did nontreated leaves, with a reduction of 73.0 and 76.3%, respectively. In 1998, leaves treated with Microsphaeropsis sp., urea, Trichoderma sp., A. bombacina, and M. arundinis reduced ascospore production by 84.3, 96.6, 75.2, 96.6, and 52.2%, respectively. Based on all tests combined, the most efficient isolate was Microsphaeropsis sp. Postharvest applications of Microsphaeropsis sp. reduced the total amount of airborne ascospores trapped by 70.7 and 79.8% as compared with the nontreated plots in 1997 and 1998, respectively. Microsphaeropsis sp. provided a significant and consistent reduction in ascospore production in all tests.     

Fertility of Angus cross beef heifers after GnRH treatment on day 23 and timing of insemination in 14‐day CIDR protocol

This study compared artificial insemination pregnancy rate (AI‐PR) between 14‐day CIDR‐GnRH‐PGF2α‐GnRH and CIDR‐PGF2α‐GnRH synchronization protocol with two fixed AI times (56 or 72 hr after PGF2α). On day 0, heifers (n = 1311) from nine locations assigned body condition score (BCS: 1, emaciated; 9, obese), reproductive tract score (RTS: 1, immature, acyclic; 5, mature, cyclic) and temperament score (0, calm; and 1, excited) and fitted with a controlled internal drug release (CIDR, 1.38 g of progesterone) insert for 14 days. Within herd, heifers were randomly assigned either to no‐GnRH group (n = 635) or to GnRH group (n = 676), and heifers in GnRH group received 100 μg of GnRH (gonadorelin hydrochloride, IM) on day 23. All heifers received 25 mg of PGF2α (dinoprost, IM) on day 30 and oestrous detection aids at the same time. Heifers were observed for oestrus thrice daily until AI. Within GnRH groups, heifers were randomly assigned to either AI‐56 or AI‐72 groups. Heifers in AI‐56 group (n = 667) were inseminated at 56 hr (day 32 PM), and heifers in AI‐72 group (n = 644) were inseminated at 72 hr (day 33 AM) after PGF2α administration. All heifers were given 100 μg of GnRH concurrently at the time AI. Controlling for BCS (p < .05), RTS (p < .05), oestrous expression (p < .001), temperament (p < .001) and GnRH treatment by time of insemination (p < .001), the AI‐PR differed between GnRH treatment [GnRH (Yes – 60.9% (412/676) vs. No – 55.1% (350/635); p < .05)] and insemination time [AI‐56 – 54.6% (364/667) vs. AI‐72 – 61.8% (398/644); (p < .01)] groups. The GnRH treatment by AI time interaction influenced AI‐PR (GnRH56 – 61.0% (208/341); GnRH72 – 60.9% (204/335); No‐GnRH56 – 47.9% (156/326); No‐GnRH72 – 62.8% (194/309); p < .001). In conclusion, 14‐day CIDR synchronization protocol for FTAI required inclusion of GnRH on day 23 if inseminations were to be performed at 56 hr after PGF2α in order to achieve greater AI‐PR.     

Design of Nonionic Surfactants for Supercritical Carbon Dioxide

Interfacially active block copolymer amphiphiles have been synthesized and their self-assembly into micelles in supercritical carbon dioxide (CO2) has been demonstrated with small-angle neutron scattering (SANS). These materials establish the design criteria for molecularly engineered surfactants that can stabilize and disperse otherwise insoluble matter into a CO2 continuous phase. Polystyrene-b-poly(1,1-dihydroperfluorooctyl acrylate) copolymers self-assembled into polydisperse core-shell-type micelles as a result of the disparate solubility characteristics of the different block segments in CO2. These nonionic surfactants for CO2 were shown by SANS to be capable of emulsifying up to 20 percent by weight of a CO2-insoluble hydrocarbon into CO2. This result demonstrates the efficacy of surfactant-modified CO2 in reducing the large volumes of organic and halogenated solvent waste streams released into our environment by solvent-intensive manufacturing and process industries.     

A Feedback Mechanism to Control Apoptosis Occurs in the Digestive Gland of the Oyster Crassostrea gigas Exposed to the Paralytic Shellfish Toxins Producer Alexandrium catenella

To better understand the effect of Paralytic Shellfish Toxins (PSTs) accumulation in the digestive gland of the Pacific oyster, Crassostrea gigas, we experimentally exposed individual oysters for 48 h to a PSTs producer, the dinoflagellate Alexandrium catenella. In comparison to the effect of the non-toxic Alexandrium tamarense, on the eight apoptotic related genes tested, Bax and BI.1 were significantly upregulated in oysters exposed 48 h to A. catenella. Among the five detoxification related genes tested, the expression of cytochrome P450 (CYP1A) was shown to be correlated with toxin concentration in the digestive gland of oysters exposed to the toxic dinoflagellate. Beside this, we observed a significant increase in ROS production, a decrease in caspase-3/7 activity and normal percentage of apoptotic cells in this tissue. Taken together, these results suggest a feedback mechanism, which may occur in the digestive gland where BI.1 could play a key role in preventing the induction of apoptosis by PSTs. Moreover, the expression of CYP1A, Bax and BI.1 were found to be significantly correlated to the occurrence of natural toxic events, suggesting that the expression of these genes together could be used as biomarker to assess the biological responses of oysters to stress caused by PSTs.     

Contingency and determinism in replicated adaptive radiations of island lizards

The vagaries of history lead to the prediction that repeated instances of evolutionary diversification will lead to disparate outcomes even if starting conditions are similar. We tested this proposition by examining the evolutionary radiation of Anolis lizards on the four islands of the Greater Antilles. Morphometric analyses indicate that the same set of habitat specialists, termed ecomorphs, occurs on all four islands. Although these similar assemblages could result from a single evolutionary origin of each ecomorph, followed by dispersal or vicariance, phylogenetic analysis indicates that the ecomorphs originated independently on each island. Thus, adaptive radiation in similar environments can overcome historical contingencies to produce strikingly similar evolutionary outcomes.