Wheat cultivars and natural-based substances: Impacts on epidemiological parameters of yellow dwarf disease

For many years, control methods against aphid-transmitted barley/cereal yellow dwarf viruses (B/CYDV) in cereal fields were mainly based on the use of neonicotinoid (NNI)-coated seeds. The ban of NNI by the EU in 2018 has reinforced the interest of the scientific community in the characterization of genetic resources and biological protections to find alternatives to chemicals for the management of B/CYDV. Eleven BYDV-susceptible wheat varieties were tested using a set of experimental procedures to evaluate their potential to alter parameters linked to the biology of aphids (Rhopalosiphum padi) and spread of virus (BYDV-PAV). Moreover, two natural-based substances (azadirachtin and mineral oil) were tested for their impact on the ability of aphids to survive, colonize and transmit the virus. Results showed that the 11 genotypes tested have a level of susceptibility to virus infection similar to the susceptible reference cv. Rubisko. However, when characterization focused on virus load, latency period and aphid fecundity, partial resistance phenotypes were observed for some cultivars. Furthermore, azadirachtin increased aphid mortality and decreased aphid fecundity. Thus, in addition to genes described for their ability to limit B/CYDV infections, the genetic backgrounds of B/CYDV-susceptible wheat cultivars and azadirachtin-based treatment should be considered for future management strategies against yellow dwarf disease.     

Segmental jejunal entrapment, volvulus, and strangulation secondary to intra-abdominal adhesions in a dog

A 4 yr old, castrated male dachshund was presented for lethargy, restlessness, a "hunched" posture, and a painful abdomen. A gastric foreign body had been surgically removed 24 mo previously. Exploratory celiotomy revealed a devitalized segment of jejunum with twisted mesentery. Several adhesions and fibrous bands were present within the abdomen, presumptively from the previous gastric foreign body surgery. Histopathology determined that a fibrous tissue band caused entrapment of the segment of intestine and its mesentery resulting in volvulus and ischemic necrosis of the intestine. This case is unique because it involved a focal area of the jejunum that was incarcerated in fibrous adhesions.     

Isolation of differentially expressed genes during interactions between tomato cells and a protective or a non-protective strain of Fusarium oxysporum

Pathogenic isolates of Fusarium oxysporum applied on a non-host plant species, as soil-borne non-pathogenic isolates, are able to protect this plant against pathogenic strains inducing wilts. Several modes of action contribute to the biocontrol activity of these protective strains; however the genetic basis of the biocontrol mechanisms is far from being understood. The aim of this study was to identify genes involved in biocontrol activity of F. oxysporum using an original model made of Fom24, a strain protective on tomato and its mutant rev157 which has lost its protective capacity. A Rapid Subtractive Hybridization (RaSH) approach was chosen to identify genes up-regulated in the protective or in the non-protective interaction when germinated conidia of either Fom24 or rev157 are confronted to tomato cell cultures. A total of 86 up-regulated sequences were generated, 42 and 44 from the protective and the non-protective interaction respectively. Homology searches led to identification of both plant and fungal genes that were grouped according to their putative functions. Among plant genes, those involved in plant response to stresses were the most abundant. Expression profiles of genes homolog to a basic endochitinase, a ferredoxine-NADP(H) reductase (FNR), an ATP synthase and the RPM1-interacting protein 4 (RIN4) were confirmed by Northern blotting. A large proportion of fungal sequences were encoding genes of unknown function; among other, those involved in response to oxidative stress and a gene putatively encoding an enolase are the most promising to further study their potential role in the protective interaction between F. oxysporum and tomato.     

Self-recognition among different polyprotic macroions during assembly processes in dilute solution

We report a self-recognition phenomenon based on an assembly process in a homogeneous dilute aqueous solution of two nano-scaled, spherical polyprotic metal oxide-based macroions (neutral species in crystals), also called Keplerates of the type [(linker)??(pentagon)??]≡[{M(H?O)}??{(Mo)Mo?}??] where M is Fe(III) or Cr(III). Upon deprotonation of the neutral species, the resulting macroions assemble into hollow "blackberry"-type structures through very slow homogeneous dimer-oligomerization processes. Although the geometrical surface structures of the two macroions are practically identical, mixtures of these form homogeneous superstructures, rather than mixed species. The phase separation is based on the difference in macroionic charge densities present during the slow homogeneous dimer or oligomer formation. The surface water ligands' residence times of Cr(III) and Fe(III) differ markedly and lead to very different interfacial water mobilities between the Keplerates.     

Effect of some repetitive factors on turbot stress response

The stress response of the turbot, Scopthalmus maximus (L.), to repetitive factors including netting, air exposure, blood sampling and hand-stripping, were tested using two different tank sizes as well as two blood sampling techniques. Exposure of juvenile fish to air for 1-4 min had no immediate effect on plasma cortisol concentrations or haematocrit values. Similarly, the serial netting of immature fish from tanks did not significantly modify plasma cortisol concentrations, haematocrit or osmolarity values. Hand-stripping of mature males was more disturbing than air exposure. The cumulative effect on plasma cortisol levels and osmolarity of stress factors such as netting, air exposure, blood sampling and stripping applied simultaneously to mature males in a 16 m3 tank and repeated twice daily for several days was recorded. The level of cortisol increased from 5 ng ml-1 to 300 ng ml-1 after 10 days of treatment, while an osmoregulatory imbalance and fish death were observed. Moreover, adaptation of fish to smaller tanks seemed to improve the increased plasma cortisol levels and death rate. Reduction in the number of stress factors applied greatly decreased both the range of physiological responses and the death rate. In order to avoid a cumulative stress response, handling of fish should therefore be reduced to a minimum.     

人工育苗条件下大黄鱼仔、稚、幼鱼的摄食与生长

在人工育苗条件下,对0到40日龄大黄鱼(Pseudosciaenacrocea,Richardson)仔、稚鱼及早期幼鱼的摄食习性与生长特性进行研究。水温(24±1)℃时,孵化后0～5d属于仔鱼期,6～20d为稚鱼期,第21天起转为幼鱼期。大黄鱼仔鱼孵化3d后开口摄食;开口时平均口径为240μm,40日龄达2480μm;口径的大小变化与日龄的关系是:y=0.2327e0.0682x,R2=0.9492。试验用的生物饵料与实际生产一致,包括轮虫、丰年虫无节幼体、活桡足类和冷藏桡足类。不同生长期的大黄鱼鱼苗的摄食活动具有明显的昼夜节律:在1昼夜(24h)中,仔鱼仅在18:00左右出现1个摄食高峰,而稚鱼和幼鱼除了在18:00左右出现1个显著的摄食高峰外,在10:00左右还有1个相对小的摄食高峰。仔、稚、幼鱼夜间基本不摄食。大黄鱼鱼苗具有较高的摄食率和饱食率,随着生长而迅速升高。仔、稚、幼鱼的生长速度具有明显的阶段性,1～2日龄仔鱼生长较快,5～9日龄生长减慢,21～30日龄生长加快,31～40日龄生长减慢。这与鱼苗的食物转换和饵料生物的营养变化有关:5～9日龄生长减慢是由于鱼苗由混合营养转变为外源性营养所致;31～40日龄生长减慢是因为冷藏桡足类的营养价值较低。鱼体全长与日龄的关系式为y=3.2552e0.0472x,R2=0.9710;体长与日龄的关系式为y=3.3205e0.0374x,R2=0.9777;     

Equine Piroplasmosis

Equine piroplasmosis (EP) is a tick-borne protozoal disease of horses, mules, donkeys, and zebras that is characterized by acute hemolytic anemia. The etiologic agents are two hemoprotozoan parasites, Theileria equi (Laveran, 1901) and Babesia caballi (Nutall and Strickland, 1910) that are transmitted primarily by ixodid ticks. Equine piroplasmosis is found globally where tick vectors are present and is endemic in tropical, subtropical, and some temperate regions. Horses infected with B. equi remain seropositive for life; horses infected with B. caballi are seropositive for several years to life. Economic losses associated with EP are significant and include the cost of treatment, especially in acutely infected horses; abortions; loss of performance; death; and restrictions in meeting international requirements related to exportation or participation in equestrian sporting events. Equine babesiosis–free countries limit the entrance of Babesia-seropositive horses into their countries. In the United States a few sporadic outbreaks have occurred in recent years but have been limited due to implementation of stringent control methods. The cELISA for both T. equi and B. caballi is currently the recommended test for international horse transport. Different therapies for control and sterilization of the parasites are discussed.     

Potential use of Eucalyptus globulus essential oil against Phytophthora colocasiae the causal agent of taro leaf blight

This study was carried out to determine the antimicrobial activity of essential oil derived from leaves of eucalyptus (Eucalyptus globulus) against Phytophthora colocasiae, the causal agent of taro leaf blight (TLB). Essential oil was obtained by Clevenger-type water distillation. The major compounds in this essential oil were identified using gas chromatography (GC) and gas chromatography coupled with mass spectrometry (GC/MS). Antimicrobial activity of the essential oil was tested in vitro against mycelial growth, sporangia and zoospores germination of P. colocasiae. Additionally, in situ tests were conducted on detached healthy taro leaves discs and evaluating necrosis symptoms of TLB were assessed. Results of the chemical composition of the essential oil analysis showed that, 1.8-cineole (26.4 %), α-pinene (14.1 %) and p-cymene (10.2 %) are the most abundant compounds. In addition, four components could be identified in noticeable amounts (18.1 % in the total): regulator G1/G2 and its derivatives as well as flavesone, a regulator G3 derivative. G is a generic term for a family of 2,3-dioxabicyclo[4,4,0] decane system growth regulators. Here, G-regulators and derivatives are described for the first time in E. globulus. Antimicrobial activity of the essential oil was recorded with total inhibition of mycelia growth and sporangia germination at 0.625 mg/ml, while the complete inhibition of zoospores germination was recorded at 0.156 mg/ml. In situ results showed that essential oil completely inhibited the appearance of disease symptoms, necrosis development and sporulation at 3.5 mg/ml. These results demonstrated that, the essential oil of Eucalyptus globulus has high ability to inhibit the development of P. colocasiae, and might be used for controlling TLB.