Intracellular interference of infectious bursal disease virus

A search for dominant-negative mutant polypeptides hampering infectious bursal disease virus (IBDV) replication has been undertaken. We have found that expression of a mutant version of the VP3 structural polypeptide known as VP3/M3, partially lacking the domain responsible for the interaction with the virus-encoded RNA polymerase, efficiently interferes with the IBDV replication cycle. Transformed cells stably expressing VP3/M3 show a significant reduction (up to 96%) in their ability to support IBDV growth. Our findings provide a new tool for the characterization of the IBDV replication cycle and might facilitate the generation of genetically modified chicken lines with a reduced susceptibility to IBDV infection.     

Azo dye reduction by mesophilic and thermophilic anaerobic consortia

The reduction of the azo dye model compounds Reactive Red 2 (RR2) and Reactive Orange 14 (RO14) by mesophilic (30 degrees C) and thermophilic (55 degrees C) anaerobic consortia was studied in batch assays. The contribution of fermentative and methanogenic microorganisms in both temperatures was evaluated in the presence of the fermentative substrate glucose and the methanogenic substrates acetate, H2/CO2, methanol, and formate. Additionally, the effect of the redox mediator riboflavin on electron shuttling was assessed. We concluded that the application of thermophilic anaerobic treatment is an interesting option for the reductive decolorization of azo dyes compared to mesophilic conditions. The use of high temperature may decrease or even take the place of the need for continuous redox mediator dosage in bioreactors, contrarily to the evident effect of those compounds on dye reduction under mesophilic conditions. Both fermenters and methanogens may play an important role during reductive decolorization of dyes, in which mediators are important not only for allowing the different microbes to participate more effectively in this complex reductive biochemistry but also for assisting in the competition for electrons between dyes and other organic and inorganic electron acceptors.     

Effects of 6-methoxy-2-benzoxazolinone on the germination and alpha-amylase activity in lettuce seeds

Germination of lettuce seeds was inhibited by 6-methoxy-2-benzoxazolinone (MBOA) at concentrations greater than 0.03 mmol/L. MBOA also inhibited the induction of alpha-amylase activity in the lettuce seeds at concentrations greater than 0.03 mmol/L. These two concentration-response curves for the germination and alpha-amylase indicate that the percentage of the germination was positively correlated with the activity of alpha-amylase in the seeds. Lettuce seeds germinated around 18h after incubation and inhibition of alpha-amylase by MBOA occurred within 6h after seed incubation. These results show that MBOA may inhibit the germination of lettuce seeds by inhibiting the induction of alpha-amylase activity.     

Movement, toxicity, and persistence of imidacloprid in seedling Tabasco pepper infested with Myzus persicae (Hemiptera: Aphididae)

Application of imidacloprid to the soil in which Tabasco pepper, Capsicum frutescens L., seedlings were growing was highly effective against the green peach aphid, Myzus persicae (Sulzer) (Hemiptera: Aphididae). In just 48 h after the soil drench, aphid numbers on treated plants declined from 292.1 to 33.0 per plant, a reduction of 89%. By 72 and 96 h after the application, the reductions were 97 and 100%, respectively. Reductions in green peach aphid numbers also indicated that imidacloprid readily moved throughout the Tabasco pepper plant. Although, initial green peach aphid reductions at 24 and 48 h after imidacloprid application to soil, were greater on the lower leaves than on the upper leaves, by 72 h toxicity was high throughout the plant. At 48 h, overall green peach aphid reduction on seedlings grown in wet soil was significantly higher than that on plants growing in the drier soil. Regardless of soil moisture or leaf location, no live green peach aphids were detected on treated seedlings after 96 h. After the initial uptake period, toxicity to green peach aphid remained high for 5 wk. Under Tabasco pepper production conditions in Central America, the greatest need for aphid management is just after transplanting. Imidacloprid soil drenches before transplanting should offer the Tabasco pepper producer an extended period of aphid-free production.     

Arterial baroreflex alters strength and mechanisms of muscle metaboreflex during dynamic exercise

Previous studies showed that the arterial baroreflex opposes the pressor response mediated by muscle metaboreflex activation during mild dynamic exercise. However, no studies have investigated the mechanisms contributing to metaboreflex-mediated pressor responses during dynamic exercise after arterial baroreceptor denervation. Therefore, we investigated the contribution of cardiac output (CO) and peripheral vasoconstriction in mediating the pressor response to graded reductions in hindlimb perfusion in conscious, chronically instrumented dogs before and after sinoaortic denervation (SAD) during mild and moderate exercise. In control experiments, the metaboreflex pressor responses were mediated via increases in CO. After SAD, the metaboreflex pressor responses were significantly greater and significantly smaller increases in CO occurred. During control experiments, nonischemic vascular conductance (NIVC) did not change with muscle metaboreflex activation, whereas after SAD NIVC significantly decreased with metaboreflex activation; thus SAD shifted the mechanisms of the muscle metaboreflex from mainly increases in CO to combined cardiac and peripheral vasoconstrictor responses. We conclude that the major mechanism by which the arterial baroreflex buffers the muscle metaboreflex is inhibition of metaboreflex-mediated peripheral vasoconstriction.     

Ethnobotany and domestication in Xoconochtli,Stenocereus stellatus (Cactaceae), in the Tehuacán Valley and La Mixteca Baja, México

Ethnobotanical information is presented on use, management, folk nomenclature and classification of the “xoconochtli” (Stenocereus stellatus) as well as on the role of this plant in subsistence of the Nahua, Mixtec and Popoloca peoples from the Tehuacán Valley and La Mixteca Baja in Central Mexico. Among all three groups, S. stellatus was used for various purposes but mainly for its edible fruits. Different variants of this species were distinguished, named and classified by indigenous people according to characteristics of the fruit; particularly size, color and flavor of the pulp, spininess and thickness of the peel. Wild plants characteristically had small red sour fruits with many spines and thick peel, while individuals selected for cultivation usually differed in one or more of these characters. Three general forms of interaction between people and this species were found: 1) gathering of useful products from the wild; 2) management of wild populations in situ which involves the sparing and enhancing of individuals with more desirable characteristics and the removal of others during clearance of the land for agriculture; and 3) cultivation, mainly in home gardens, by propagation of vegetative parts from desirable individuals. Fruit yields per individual and per population were measured and compared in wild, managed in situ and cultivated populations from the Tehuacán Valley and La Mixteca Baja. Wild and cultivated individuals from La Mixteca Baja yielded more than wild and cultivated individuals from the Tehuacán Valley. Within each region, fruit yields were similar in wild and managed in situ populations but significantly larger in cultivated populations. Forms of management of this plant species are discussed in terms of availability of products and demand for them in the local economy.