High Levels Of Susceptibility Research Articles

Tolerance Expression of Maize Genotypes to Exserohilum turcicum in North and South Korea

Northern corn leaf blight caused by Exserohilum turcicum Pass is considered the most important disease infecting corn (Zea mays L.) in the Peoples’ Republic of Korea (North Korea). It contributes to the food shortage in North Korea. The objectives of the current research were to study resistance expression and responses of corn crosses made between ten hybrids from North Korea and inbreeding lines (S 3-4 stage) from the Republic of Korea (South Korea). The experiments were conducted in six trials with a total of 184 crosses including two commercial hybrids in each trial. The trials were conducted at two locations in North Korea (Mirim and Eunsan) and one location in South Korea (Gunwi) under natural infestation of E. turcicum. Host plant responses were rated on a scale of 1 (highly tolerant) to 9 (highly susceptible). A total of 111 crosses (62.4%) showed significant tolerant or susceptible response variations among three locations; 42 crosses (22.8%) at two locations and 69 crosses (39.0%) at one location, respectively. At least 8 crosses of high level of tolerance and 12 crosses of high level of susceptibility showed significantly different biotic responses (P = 0.05). The results of the current study and historical reviews of E. turcicum epidemics in both North and South Korea suggest that breeding of tolerance with quantitatively inherited genes should be carried out for a sustainable corn production in North Korea.

Epididymis Response Partly Compensates for Spermatozoa Oxidative Defects in snGPx4 and GPx5 Double Mutant Mice

We report here that spermatozoa of mice lacking both the sperm nucleaus glutathione peroxidase 4 (snGPx4) and the epididymal glutathione peroxidase 5 (GPx5) activities display sperm nucleus structural abnormalities including delayed and defective nuclear compaction, nuclear instability and DNA damage. We show that to counteract the GPx activity losses, the epididymis of the double KO animals mounted an antioxydant response resulting in a strong increase in the global H2O2-scavenger activity especially in the cauda epididymis. Quantitative RT-PCR data show that together with the up-regulation of epididymal scavengers (of the thioredoxin/peroxiredoxin system as well as glutathione-S-transferases) the epididymis of double mutant animals increased the expression of several disulfide isomerases in an attempt to recover normal disulfide-bridging activity. Despite these compensatory mechanisms cauda-stored spermatozoa of double mutant animals show high levels of DNA oxidation, increased fragmentation and greater susceptibility to nuclear decondensation. Nevertheless, the enzymatic epididymal salvage response is sufficient to maintain full fertility of double KO males whatever their age, crossed with young WT female mice.

Levofloxacin for the treatment of respiratory tract infections

Introduction: Fluoroquinolone use has dramatically increased since the introduction of the first respiratory fluoroquinolone in the late 1990s. Levofloxacin, like other fluoquinolones, is a potent antibiotic, due to high levels of susceptibility among Gram-negative, Gram-positive (including penicillin-resistant strains of Streptococcus pneumonia) and atypical pathogens. Levofloxacin is recommended for the treatment of community-acquired pneumonia (CAP), hospital-acquired pneumonia (HAP) and in the management of acute exacerbations of chronic bronchitis (AECB). Levofloxacin demonstrates good safety, bioavailability and tissue penetration, thus maintaining adequate concentrations at the site of infection. High-dose (750 mg), short-course (5 days) therapy regimens may offer improved treatment, especially in HAP, due to higher drug concentrations, increased adherence and the potential to reduce the development of resistance.Areas covered: This article covers medical literature published in any language since 1990 until November 2011, on ‘levofloxacin’, identified using PubMed and MEDLINE. The search terms used were ‘levofloxacin’ and ‘community acquired pneumonia’, ‘hospital pneumonia’ or ‘AECB’.Expert opinion: Levofloxacin is a valuable antimicrobial agent and an optimal treatment option for AECB, CAP (as a monotherapy) and HAP (as combination therapy at a high-dose regimen). Its improved bioavailability and safety profile makes the possibility of shorter hospital stays a reality.

Modeling susceptibility to deforestation of remaining ecosystems in North Central Mexico with logistic regression

Determining underlying factors that foster deforestation and delineating forest areas by levels of susceptibility are of the main challenges when defining policies for forest management and planning at regional scale. The susceptibility to deforestation of remaining forest ecosystems (shrubland, temperate forest and rainforest) was conducted in the state of San Luis Potosi, located in north central Mexico. Spatial analysis techniques were used to detect the deforested areas in the study area during 1993–2007. Logistic regression was used to relate explanatory variables (such as social, investment, forest production, biophysical and proximity factors) with susceptibility to deforestation to construct predictive models with two focuses: general and by biogeographical zone. In all models, deforestation has positive correlation with distance to rainfed agriculture, and negative correlation with slope, distance to roads and distance to towns. Other variables were significant in some cases, but in others they had dual relationships, which varied in each biogeographical zone. The results show that the remaining rainforest of Huasteca region is highly susceptible to deforestation. Both approaches show that more than 70% of the current rainforest area has high and very high levels of susceptibility to deforestation. The values represent a serious concern with global warming whether tree carbon is released to atmosphere. However, after some considerations, encouraging forest environmental services appears to be the best alternative to achieve sustainable forest management.

Life History of Pink Hibiscus Mealybug,Maconellicoccus hirsutus(Hemiptera: Pseudococcidae) on ThreeHibiscusRosa-SinensisCultivars

ABSTRACT The pink hibiscus mealybug, Maconellicoccus hirsutus Green, is a widespread invasive pest of Hibiscus rosa-sinensis in Florida and elsewhere. We evaluated 3 cultivars of H. rosa-sinensis expected to have high (‘President’), low (‘Double Red’), and intermediate (‘Joanne’) levels of susceptibility to this pest. We found little evidence that M. hirsutus responded differently among the 3 cultivars in terms of survival, development rate, size, or oviposition period in laboratory tests at a permissive temperature. However, higher average fecundity (377 eggs per female) was observed on “President” compared with the other 2 cultivars (≈ 300 eggs/female). The Fl generation developed on all varieties, with similar cumulative survival rates of 71, 74, and 76% on “Double Red”, “Joanne” and “President” cultivars, respectively. In greenhouse tests over 9 wk, feeding symptoms of stunted and deformed plant terminals (“bunchy top”) were observed in all cultivars but increased more rapidly in “President”, especial...

Dexamethasone modulates expression of genes involved in the innate immune system, growth and stress and increases susceptibility to bacterial disease in Senegalese sole (Solea senegalensis Kaup, 1858)

Cortisol, the main glucocorticoid in fish, undertakes pleiotropic biological effects in response to stressors to maintain homeostasis. It can exert several actions on the immune system, growth and cellular metabolism, establishing a fine-tune regulation stress response and cross-talk interactions with other regulatory pathways. In this study, we investigated a causal relationship between high levels of glucocorticoids and susceptibility to pathogens and modification of gene expression profiles in Senegalese sole. For this purpose, we carried out two experiments using post-metamorphic individuals (21 days after hatching) that were exposed to dexamethasone (DXM), a potent glucocorticoid, in order to mimic cortisol effects. We quantified transcript levels of a wide set of genes involved in innate immune system (g-type lysozyme and hepcidin (hamp1)), HPI axis (crf, crfbp, pomcα, pomcβ, gr1 and gr2), HPT axis (tgb), cellular stress defense system (hsp70 and hsp90aa), GH/IGF axis (igf-I and igf-Ir) and the neuropeptide trh. Short-term exposure to 0.1, 1 and 10 ppm DXM provoked a reduction of pomcβ transcripts and an increase of crfbp mRNAs in a dose-dependent manner at 48 and 72 h after treatment. Moreover, g-type lysozyme transcript levels decreased significantly at 72 h whereas hamp1 mRNA levels increased at 48 h after exposure. Long-term DXM treatment (10 ppm DXM) affected negatively weight of soles (∼20% lower than controls). Moreover, reduced mRNA levels were observed for pomcβ after 1 week and igf-I and hamp1 after 2 weeks. In contrast, crfbp and crf increased mRNA levels after 2 weeks. hsp70 exhibited a dual response increasing transcript levels at 1 week after treatment and reducing thereafter. No significant changes in gene expression were observed at any time during this study for tgb, trh, hsp90aa, pomcα, gr1 and gr2. Finally, a challenge experiment using the pathogen Photobacterium damselae subsp piscicida confirmed earlier and higher mortalities in DXM-treated animals. Taken together, these data indicate that a prolonged exposure to DXM increases the susceptibility to pathogens and reduces growth. Moreover, DXM can trigger a wide cellular response modulating the expression of genes involved in the innate immune system, HPI and GH/IGF axes as well as cellular stress defense. These results are highly valuable to evaluate responses associated to aquaculture stressful conditions and discriminate specific glucocorticoid-mediated effects.

Serum-free culture of an embryonic cell line from Bombyx mori and reinforcement of susceptibility of a recombinant BmNPV by cooling

We established the first continuous cell line that uses a serum-free culture from the embryo of Bombyx mori (Lepidoptera: Bombycidae), designated as NIAS-Bm-Ke17. This cell line was serially subcultured in the SH-Ke-117 medium. The cells adhere weakly to the culture flask, and most cells have an oval shape. The cell line was subcultured 154 times, and the population doubling time is 83.67±5.22 h. Random amplification of polymorphic DNA-polymerase chain reaction with a tenmar single primer for discrimination of insect cell lines recognized the NIAS-Bm-Ke1 cell line as B. mori. This cell line does not support the growth of the B. mori nuclear polyhedrosis virus (BmNPV) in the absence of the heat-inactivated hemolymph of B. mori. However, the heat-inactivated hemolymph in 1% volume of the medium supported a high level of susceptibility to BmNPV. In addition, the cooling treatment of the cells at 2.5°C also enhanced the susceptibility. We report a new serum-free culture system of the B. mori cell line for the baculovirus expression vector system.

Gene expression in Atlantic salmon skin in response to infection with the parasitic copepod Lepeophtheirus salmonis, cortisol implant, and their combination

BackgroundThe salmon louse is an ectoparasitic copepod that causes major economic losses in the aquaculture industry of Atlantic salmon. This host displays a high level of susceptibility to lice which can be accounted for by several factors including stress. In addition, the parasite itself acts as a potent stressor of the host, and outcomes of infection can depend on biotic and abiotic factors that stimulate production of cortisol. Consequently, examination of responses to infection with this parasite, in addition to stress hormone regulation in Atlantic salmon, is vital for better understanding of the host pathogen interaction.ResultsAtlantic salmon post smolts were organised into four experimental groups: lice + cortisol, lice + placebo, no lice + cortisol, no lice + placebo. Infection levels were equal in both treatments upon termination of the experiment. Gene expression changes in skin were assessed with 21 k oligonucleotide microarray and qPCR at the chalimus stage 18 days post infection at 9°C. The transcriptomic effects of hormone treatment were significantly greater than lice-infection induced changes. Cortisol stimulated expression of genes involved in metabolism of steroids and amino acids, chaperones, responses to oxidative stress and eicosanoid metabolism and suppressed genes related to antigen presentation, B and T cells, antiviral and inflammatory responses. Cortisol and lice equally down-regulated a large panel of motor proteins that can be important for wound contraction. Cortisol also suppressed multiple genes involved in wound healing, parts of which were activated by the parasite. Down-regulation of collagens and other structural proteins was in parallel with the induction of proteinases that degrade extracellular matrix (MMP9 and MMP13). Cortisol reduced expression of genes encoding proteins involved in formation of various tissue structures, regulators of cell differentiation and growth factors.ConclusionsThese results suggest that cortisol-induced stress does not affect the level of infection of Atlantic salmon with the parasite, however, it may retard repair of skin. The cortisol induced changes are in close concordance with the existing concept of wound healing cascade.

Reação de acessos de Capsicum e de progênies de cruzamentos interespecíficos a isolados de Colletotrichum acutatum

A antracnose, causada por um complexo de espécies de Colletotrichum, é uma das doenças mais importantes de Capsicum em regiões tropicais e subtropicais. Fontes de resistência têm sido identificadas em programas de melhoramento conduzidos em diferentes continentes. No entanto, ainda são restritas as informações sobre a abrangência e estabilidade desta resistência aos diferentes isolados de espécies de Colletotrichum que compõem o complexo causador da antracnose em Capsicum. Foram avaliadas as reações de 129 acessos de espécies de Capsicum e de progênies derivadas de cruzamentos interespecíficos (C. annuum x C. chinense PBC 932) a cinco isolados de C. acutatum, em plântulas e frutos e verificada a correlação entre a reação nesses dois estádios. Pela análise de agrupamento, um acesso de C. annuum, um de C. baccatum e dois de C. chinense foram classificados como resistentes. Grande variabilidade de respostas à antracnose foi observada nas progênies derivadas do cruzamento interespecífico variando desde extrema suscetibilidade (55%) até progênies sem lesões (10%). Não foi detectada correlação significativa entre a reação de plântulas e frutos. Os resultados indicam que a resistência do acesso C. chinense PBC 932 possui estabilidade e amplo espectro contra diferentes isolados da espécie C. acutatum e que há possibilidade de incorporar os genes de resistência à antracnose de PBC 932 em linhagens elite via métodos clássicos de melhoramento.

Dietary Cholesterol-Induced Post-Testicular Infertility

This work shows that an overload of dietary cholesterol causes complete infertility in dyslipidemic male mice (the Liver X Receptor-deficient mouse model). Infertility resulted from post-testicular defects affecting the fertilizing potential of spermatozoa. Spermatozoa of cholesterol-fed lxr−/− animals were found to be dramatically less viable and motile, and highly susceptible to undergo a premature acrosome reaction. We also provide evidence, that this lipid-induced infertility is associated with the accelerated appearance of a highly regionalized epididymal phenotype in segments 1 and 2 of the caput epididymidis that was otherwise only observed in aged LXR-deficient males. The epididymal epithelial phenotype is characterized by peritubular accumulation of cholesteryl ester lipid droplets in smooth muscle cells lining the epididymal duct, leading to their transdifferentiation into foam cells that eventually migrate through the duct wall, a situation that resembles the inflammatory atherosclerotic process. These findings establish the high level of susceptibility of epididymal sperm maturation to dietary cholesterol overload and could partly explain reproductive failures encountered by young dyslipidemic men as well as ageing males wishing to reproduce.

Are phylogenetic position, virulence, drug susceptibility and in vivo response to treatment in mycobacteria interrelated?

Phylogenetic analyses on the basis of multiple house-keeping genes and whole genome sequences have offered new insights in the phylogeny of the genus Mycobacterium. This genus yields obligate pathogens, the M. tuberculosis complex and M. leprae, as well as opportunistic pathogens (e.g. M. avium, M. intracellulare, M. kansasii, M. marinum, M. malmoense) and saprophytes (e.g. M. phlei, M. sphagni, M. gordonae). The most virulent mycobacteria, the M. tuberculosis complex, M. leprae and the M. kansasii-M. szulgai-M. marinum-M. ulcerans group are phylogenetically related and infections by these organisms are better treatable than those caused by less virulent and phylogenetically more distantly related Mycobacterium species. The most virulent Mycobacterium species are also characterized by high levels of natural drug susceptibility. In this paper, we review studies of phylogeny, drug susceptibility, and clinical significance to support our hypothesis that drug susceptibility in mycobacteria is acquired and reflects the low level of competition in -and adaptation to- a closer-to-human (environmental) niche. In turn, mycobacteria that inhabit the most competitive environmental niches are the least adapted to humans, thus of low clinical significance, but most tolerant to antibiotics derived from microbes with which they share their habitat, lowering the chances of cure in case of infection.

The Association Between Point-of-Sale Displays and Youth Smoking Susceptibility

According to tobacco industry documents, tobacco displays within the retail environment assume a much greater importance with the loss of other marketing channels. The impact of these displays upon young people and their future intentions to smoke (susceptibility) is, therefore, of significant interest to public health. A cross-sectional in-home survey was conducted in 2008 with young people (N = 1,401) aged 11-16 years, recruited from across the United Kingdom. We examine the salience of and attraction to cigarette displays at point-of-sale (POS), among youth, and whether this is associated with susceptibility. We concentrate exclusively on the 956 never-smokers. Logistic regression, controlling for known risk factors of youth smoking, found that noticing cigarette displays was associated with higher levels of susceptibility (odds ratio [OR] = 1.77, p < .05) and greater attraction to displays was associated with higher susceptibility (OR = 1.07, p < .001). It is difficult, if not impossible, to safeguard young people from exposure to displays of tobacco at POS. That these displays were associated with increased susceptibility suggests that moves to place tobacco out of sight in the United Kingdom, and elsewhere, are justified.

Sero-epidemiology of measles-specific IgG antibodies and predictive factors for low or missing titres in a German population-based cross-sectional study in children and adolescents (KiGGS)

In the European Region, measles elimination is now targeted to 2015. To measure progress towards elimination age-group specific susceptibility targets have been defined. Age-specific measles susceptibility in children and adolescents was evaluated in Germany. Taking into account a broad range of socio-demographic, health- and vaccination status related variables, populations for vaccination campaigns were identified. We analysed data from children aged 1-17 years in the representative German Health Interview and Examination Survey for Children and Adolescents (KiGGS). Measles immunoglobulin G antibodies were measured in 13,977 participants by enzyme immunoassay (ELISA). Bivariate and multivariate logistic regression analyses were used to determine parental and infant related factors associated with measles susceptibility. The overall prevalence of seronegativity in children tested for measles IgG aged 1-17 years was 10.0% (95% CI 9.4-10.7). The prevalence of seronegativity in the German population was below the WHO targets for measles elimination in children aged 2-9 year-olds but exceeded the target for 10-17 year-olds. Age differences in the level of seronegativity were found to be mainly due to differences in vaccination coverage. A higher level of susceptibility was observed if parents did not comply with the request to present the child's vaccination card. In vaccinated children, immigration, male gender, very young age at first vaccination and a longer time period since last vaccination were associated with a higher level of susceptibility. Further increase of the two-dose vaccination coverage is necessary in order to achieve the WHO targets. Catch up vaccination campaigns should focus on adolescents and immigrants.

Susceptibility of bacterial isolates from community‐acquired infections in sub‐Saharan Africa and Asia to macrolide antibiotics

To review the literature on the susceptibility of common community pathogens in sub-Saharan Africa and Asia to the macrolide antibiotics. Inclusion criteria required that isolates were collected since 2004 to ensure results were of contemporary relevance. The data were aggregated by region, age group and sterility of site of culture sample. A total of 51 studies were identified, which reported the macrolide antimicrobial susceptibilities of common bacterial pathogens isolated since 2004. In general, there was less macrolide resistance in African than in Asian isolates. Most African studies reported high levels of macrolide susceptibility in Streptococcus pneumoniae, whereas most Chinese studies reported high levels of resistance. There was very little information available for Gram-negative organisms. Susceptibility of the pneumococcus to macrolides in SSA remains high in many areas, and good activity of azithromycin has been shown against Salmonellae spp. in Asia. In urban areas where high antibiotic consumption is prevalent, there was evidence of increased resistance to macrolides. However, there is no information on susceptibility from large areas in both continents.

Molecular epidemiology and genetic diversity of pneumococcal carriage among children in Beni State, Bolivia

During 2007, a study of pneumococcal carriage in children was performed in two towns (Trinidad and Riberalta) in the Beni region of the Bolivian Amazon basin. Little has previously been reported regarding the epidemiology of pneumococcal carriage in Bolivia, and no multilocus sequence typing (MLST) of pneumococcal isolates from this region has previously been documented. A pneumococcal carriage rate of 34% was identified. Of 53 Streptococcus pneumoniae isolates that survived transportation for serotyping, antibiotic susceptibility testing and MLST, the commonest serotypes were 6A (9%), 34 (8%), 4 (6%), 9A (6%), 10A (6%), 19A (6%), 23F (6%) and 38 (6%); overall, 26 different serotypes were identified. Antibiotic susceptibility testing by Etest demonstrated high levels of susceptibility to penicillin (93%), erythromycin (98%), vancomycin (100%), chloramphenicol (100%), tetracycline (96%) and trimethoprim/sulfamethoxazole (co-trimoxazole) (85%). MLST identified that the majority (57%) of viable isolates belonged to previously unrecognised sequence types that are currently unique to Bolivia.

Severity of Rice Disease Caused by Curvularia Spp In Malaysia

Curvularia is a hyphomycete fungus that is a facultative pathogen that affects many plants species especially in the tropical region. Rice researchers have documented Curvularia as one of the 6 main pathogenic fungi that infects and attacks rice. The fungus belongs to the Ascomycota phylum, from the Euascomycetes class. This pathogenic fungus causes diseases such as black kernel, speckled rice, sheath rot and sheath blight in rice worldwide. According to the International Rice Research Institute, IRRI, this disease has caused loss in yield in countries such as India, Indonesia and Thailand. Recently, Curvularia species has been isolated from all our infected or disease tissues sampled from field. In order to determine how much of the disease severity is caused by this pathogen only, we used our field isolate of Curvularia to examine disease symptoms attributed by this single pathogen on rice as host. The objective of this study is to perform a screening of rice varieties and determine level of disease severity and incidence caused by the Malaysian strain, Curvularia spp (PMLI-1). The fungal plug inoculum method was used in this study. The resulting disease symptoms were observed and recorded based on a disease symptoms scale. Based on the disease scale and the resulting symptoms, the study found that out of the 21 rice varieties used, three varieties showed high level of resistance to Curvularia spp infection, six varieties were resistance, and eight varieties of rice showed moderate resistance. Three varieties showed susceptibility and one variety showed high levels of susceptibility to Curvularia spp . Rice varieties that showed high resistance to infection of Curvularia spp are UKMRC9, UKMRC2, and Oryza nivara .

Cotton pest management practices and the selection of pyrethroid resistance in Anopheles gambiae population in Northern Benin

BackgroundPyrethroid insecticides, carbamate and organophosphate are the classes of insecticides commonly used in agriculture for crop protection in Benin. Pyrethroids remain the only class of insecticides recommended by the WHO for impregnation of bed nets. Unfortunately, the high level of pyrethroid resistance in Anopheles gambiae s.l., threatens to undermine the success of pyrethroid treated nets. This study focuses on the investigation of agricultural practices in cotton growing areas, and their direct impact on larval populations of An. gambiae in surrounding breeding sites.MethodsThe protocol was based on the collection of agro-sociological data where farmers were subjected to semi-structured questionnaires based on the strategies used for crop protection. This was complemented by bioassay tests to assess the susceptibility of malaria vectors to various insecticides. Molecular analysis was performed to characterize the resistance genes and the molecular forms of An. gambiae. Insecticide residues in soil samples from breeding sites were investigated to determine major factors that can inhibit the normal growth of mosquito larvae by exposing susceptible and resistant laboratory strains.ResultsThere is a common use by local farmers of mineral fertilizer NPK at 200 kg/ha and urea at 50 kg/hectare following insecticide treatments in both the Calendar Control Program (CCP) and the Targeted Intermittent Control Program (TICP). By contrast, no chemicals are involved in Biological Program (BP) where farmers use organic and natural fertilizers which include animal excreta.Susceptibility test results confirmed a high resistance to DDT. Mean mortality of An. gambiae collected from the farms practicing CCP, TICP and BP methods were 33%, 42% and 65% respectively. An. gambiae populations from areas using the CCP and TICP programs showed resistance to permethrin with mortality of 50% and 58% respectively. By contrast, bioassay test results of An. gambiae from BP areas gave a high level of susceptibility to permethrin with an average mortality of 94%.Molecular analysis identified An. gambiae s.s, and An. arabiensis with a high predominance of An. gambiae s.s (90%). The two molecular forms, M and S, were also determined with a high frequency of the S form (96%).The Kdr gene seemed the main target- site resistance mechanism detected in CCP, TICP, and BP areas at the rates ranging from 32 to 78%. The frequency of ace-1R gene was very low (< 0.1).The presence of inhibiting factors in soil samples under insecticide treatments were found and affected negatively in delaying the development of An. gambiae larval populations.ConclusionsThis research shows that Kdr has spread widely in An. gambiae, mainly in CCP and TICP areas where pyrethroids are extensively used. To reduce the negative impact of pesticides use in cotton crop protection, the application of BP-like programs, which do not appear to select for vector resistance would be useful. These results could serve as scientific evidence of the spread of resistance due to a massive agricultural use of insecticides and contribute to the management of pesticides usage on cotton crops hence reducing the selection pressure of insecticides on An. gambiae populations.

Monitoramento da suscetibilidade de populações de Triatoma sordida Stål, 1859 (Hemiptera: Reduviidae) ao inseticida deltametrina, na região Centro-Oeste do Brasil

Triatoma sordida Stål, 1859 populations were investigated for susceptibility to deltamethrin. This study aimed to analyze the resistance of 11 populations of insects from the States of Goiás, Mato Grosso and Mato Grosso do Sul by topical application bioassays. The estimated LD50 and RR50 showed high levels of susceptibility (LD50 < 1 and RR50 < 2). However, analysis of the slope of the dose response curve showed that the populations of insects in the towns of Firminópolis/GO, Posse/GO, Poxoréu/MT, Douradina/MS and Aparecida do Taboado/MS present great probability of evolving resistance and, thus, are more likely to tolerate treatment with deltamethrin. Small changes in susceptibility and low levels of resistance were detected, but the temporal changes of susceptibility should be continuously monitored to adequately guide the actions of vector-control of DC.

Comparison of the effects of Fusarium solani filtrates in vitro and in vivo on the morphological characteristics and peroxidase activity in pea cultivars with different susceptibility.

Intact plants and in vitro cultures of four pea (Pisum sativum) cultivars (Adept, Herold, Komet, Menhir) that vary in their degree of susceptibility/resistance to Fusarium solani were inoculated with this pathogen or treated with its culture filtrates to compare their reaction patterns at the phenotypic, histological and biochemical level. Changes in activity of three peroxidase forms, cytosolic, membrane- and ion-bound, and in peroxidase isozymes were studied in detail. In addition, the length and weight of roots of regenerating plantlets in explant cultures as well as symptom expression in intact plants were assessed. In planta, screening of the four pea cultivars revealed the highest degree of resistance in cv. Adept, and the highest level of susceptibility in cv. Menhir both to F. solani and its metabolites. Regarding in vitro cultures, the microfiltrated filtrates had stronger inhibitive effect than the autoclaved ones. In terms of peroxidase activity, the only significant difference among cultivars was found in its ionic form, for the most resistant cv. Adept versus the most sensitive cv. Menhir. Minor changes in activity of cytosolic peroxidase were noted in planta and in vitro, while the membrane- and ion-bound peroxidase significantly decreased in explants. The aim of our study was to compare reaction of pea plants and explants and to verify whether the application of fungal filtrates is able to mimic the F. solani pathogenesis. Several responses of explants to filtrates were found to be analogous to the plant reaction to pathogen infection both at morphological and physiological levels. These can be utilized in an early in vitro screening for plant tissue resistance to F. solani.

The differential expression of Rhopalosiphum padi resistance in sibling wheat-rye amphiploids

Thirteen amphiploids were synthesized by chromosome doubling of an F1 plant of a cross between Triticum aestivum Mianyang11 × S. cereale Kustro, which shows resistance to Bird cherry-oat aphid (Rhopalosiphum padi). The amphiploids were confirmed by GISH analysis and tested for their reaction to R. padi. Eleven amphiploids exhibited resistance to R. padiand two of them exhibited high level of susceptibility. The PCR analysis using rye-specific markers provided evidence for the elimination of W-box elements from the susceptible amphiploids. The possible mechanism of loss resistance in some amphiploids was discussed. The resistant amphiploids can be exploited in wheat breeding programs to transfer R. padi resistance to susceptible wheat varieties. Key words: Rhopalosiphum padi, amphiploid, wheat, rye.