Tissue distribution of residual antimony in rats treated with multiple doses of meglumine antimoniate

Meglumine antimoniate (MA) and sodium stibogluconate are pentavalent antimony (SbV) drugs used since the mid-1940s. Notwithstanding the fact that they are first-choice drugs for the treatment of leishmaniases, there are gaps in our knowledge of their toxicological profile, mode of action and kinetics. Little is known about the distribution of antimony in tissues after SbV administration. In this study, we evaluated the Sb content of tissues from male rats 24 h and three weeks after a 21-day course of treatment with MA (300 mg SbV/kg body wt/d, subcutaneous). Sb concentrations in the blood and organs were determined by inductively coupled plasma-mass spectrometry. In rats, as with in humans, the Sb blood levels after MA dosing can be described by a two-compartment model with a fast (t1/2 = 0.6 h) and a slow (t1/2 >> 24 h) elimination phase. The spleen was the organ that accumulated the highest amount of Sb, while bone and thyroid ranked second in descending order of tissues according to Sb levels (spleen >> bone, thyroid, kidneys > liver, epididymis, lungs, adrenals > prostate > thymus, pancreas, heart, small intestines > skeletal muscle, testes, stomach > brain). The pathophysiological consequences of Sb accumulation in the thyroid and Sb speciation in the liver, thyroid, spleen and bone warrant further studies.

Quantification of C4d deposition and hepatitis C virus RNA in tissue in cases of graft rejection and hepatitis C recurrence after liver transplantation

Histology is the gold standard for diagnosing acute rejection and hepatitis C recurrence after liver transplantation. However, differential diagnosis between the two can be difficult. We evaluated the role of C4d staining and quantification of hepatitis C virus (HCV) RNA levels in liver tissue. This was a retrospective study of 98 liver biopsy samples divided into four groups by histological diagnosis: acute rejection in patients undergoing liver transplant for hepatitis C (RejHCV+), HCV recurrence in patients undergoing liver transplant for hepatitis C (HCVTx+), acute rejection in patients undergoing liver transplant for reasons other than hepatitis C and chronic hepatitis C not transplanted (HCVTx-). All samples were submitted for immunohistochemical staining for C4d and HCV RNA quantification. Immunoexpression of C4d was observed in the portal vessels and was highest in the HCVTx- group. There was no difference in C4d expression between the RejHCV+ and HCVTx+ groups. However, tissue HCV RNA levels were higher in the HCVTx+ group samples than in the RejHCV+ group samples. Additionally, there was a significant correlation between tissue and serum levels of HCV RNA. The quantification of HCV RNA in liver tissue might prove to be an efficient diagnostic test for the recurrence of HCV infection.

Mir-190b negatively contributes to the Trypanosoma cruzi- infected cell survival by repressing PTEN protein expression

Chagas disease, which is caused by the intracellular protozoanTrypanosoma cruzi, is a serious health problem in Latin America. The heart is one of the major organs affected by this parasitic infection. The pathogenesis of tissue remodelling, particularly regarding cardiomyocyte behaviour after parasite infection, and the molecular mechanisms that occur immediately following parasite entry into host cells are not yet completely understood. Previous studies have reported that the establishment of parasitism is connected to the activation of the phosphatidylinositol-3 kinase (PI3K), which controls important steps in cellular metabolism by regulating the production of the second messenger phosphatidylinositol-3,4,5-trisphosphate. Particularly, the tumour suppressor PTEN is a negative regulator of PI3K signalling. However, mechanistic details of the modulatory activity of PTEN on Chagas disease have not been elucidated. To address this question, H9c2 cells were infected with T. cruzi Berenice 62 strain and the expression of a specific set of microRNAs (miRNAs) were investigated. Our cellular model demonstrated that miRNA-190b is correlated to the decrease of cellular viability rates by negatively modulating PTEN protein expression in T. cruzi-infected cells.

Natural parasitism in eggs of Anticarsia gemmatalis Hübner (Lepidoptera, Noctuidae) by Trichogramma spp. (Hymenoptera, Trichogrammatidae) in Brazil

Field surveys were carried during four soybean seasons in Southern Brazil to evaluate the occurrence of parasitoids in eggs of Anticarsia gemmatalis Hübner, 1818 and their incidence along the crop season. Eggs were collected by visual search on soybean leaves and from plants kept inside cages where A. gemmatalis moths were allowed to lay eggs. Trichogramma acacioi Brun, Moraes & Soares, 1984 was recorded for the first time in eggs of A. gemmatalis and the citations in the literature of Trichogramma lasallei Pinto, 1998 in Brazil where based on the material collected in this survey. Apart from these species, Trichogramma pretiosum Riley, 1879, Trichogramma rojasi Nagaraja & Nagarkatti, 1973 and Trichogramma atopovirilia Oatman & Platner, 1983 were also collected, all of which have been previously recorded in this host. Parasitized eggs were collected all over the period of occurrence of A. gemmatalis, from January to April each year. Total parasitism ranged from 4.8% in 2000 and 2002, 23.3% in 2001 and 28.9% in 2003. T. pretiosum and T. acacioi accounted for more than 80% of the parasitoids emerged each year, followed by T. atopovirilia, T. rojasi and T. lasallei, with less than 20% of incidence. Both the sex ratio and the mean number of parasitoids/egg did not differ among the species. Searching for A. gemmatalis eggs proved to be time consuming in comparison to the collection of eggs laid by moths inside the cages, which showed to be a useful method to provide qualitative estimates of parasitism in eggs of A. gemmatalis.

Trichogramma acacioi (Hymenoptera, Trichogrammatidae) parasitism capacity at different temperatures and factitious hosts

It was studied the parasitism capacity of Trichogramma acacioi on Anagasta kuehniella and Sitotroga cerealella eggs at different temperatures (15, 20, 25, 30 and 35 ± 1°C). The parasitism of T. acacioi varied with temperature and host. The highest parasitism (³80%) were observed during the first days after emergence in both hosts, at all tested temperatures. The accumulated parasitism varied with both host and temperature, being higher on A. kuehniella at 20°C, what shows good parasitoid species adaptation to this temperature. Thus, we conclude that the best host and best temperature to be used at mass-rearing of T. acacioi is A. kuehniella and 20ºC, respectively. Moreover, this Trichogramma species has great potential to be used in field releases at regions where average temperature is around 20ºC.

Biological characteristics and parasitism capacity of Trichogramma pretiosum Riley (Hymenoptera, Trichogrammatidae) on eggs of Spodoptera frugiperda (J. E. Smith) (Lepidoptera, Noctuidae)

This study aimed at evaluating the biological characteristics and the capacity of parasitism of a Trichogramma pretiosum Riley, 1869 (Hymenoptera, Trichogrammatidae) strain (T. pretiosum RV) collected in Rio Verde County, State of Goiás, Brazil. The study was carried out on eggs of Spodoptera frugiperda (J. E. Smith, 1797) (Lepidoptera, Noctuidae) and conducted under controlled environmental conditions at different constant temperatures. The biological parameters determined were: developmental time (egg-adult; days); emergence (%); sex ratio; number of progeny/egg; number of generation/year; thermal constant (K); temperature threshold (Tb); daily number of parasitized eggs; cumulative parasitism (%); total number of eggs parasitized by T. pretiosum; and female longevity. To study the T. pretiosum parasitism capacity, 20 S. frugiperda eggs (< 24 h old) were placed into 8.0 cm x 2.0 cm glass vials containing one female (< 24 h old) each. Trials were carried out in a completely randomized experimental design, with 20 replications at each temperature. The environmental chambers (BOD type) were set at 18ºC, 20ºC, 22ºC, 25ºC, 28ºC and 32ºC ± 1ºC, 70 ±10% relative humidity, and 14/10 h (L:D) photoperiod. The eggs of S. frugiperda were replaced daily until parasitoid death. Results have shown an inverse correlation between developmental time and temperature, with statistically significant differences among means, except at 25ºC and 28ºC (10 days). Parasitoid emergence (%) was also influenced by temperature. The lowest percent emergence was observed at 32ºC, and the highest ones at 18ºC and 20ºC temperatures. The temperature did not affect T. pretiosum sex ratio and number of parasitoids per egg, thus allowing changes in the temperature to control insect mass production in the laboratory to meet the needs for field releases.

First report of parasitism on pupae of Opsiphanes invirae amplificatus Stichel (Lepidoptera, Nymphalidae) by Conura (Conura) maculata (Fabricius) (Hymenoptera, Chalcididae) in Rio Grande do Sul, Brazil

First report of parasitism on pupae of Opsiphanes invirae amplificatus Stichel (Lepidoptera, Nymphalidae) by Conura (Conura) maculata (Fabricius) (Hymenoptera, Chalcididae) in Rio Grande do Sul, Brazil. This scientific note records the parasitism on pupae of Opsiphanes invirae amplificatus Stichel (1904) by Conura (Conura) maculata (Fabricius). This is a report of this interaction in the subtropical region of South America and the first report of the occurrence of this parasitoid in the state of Rio Grande do Sul, Brazil.

First report of interspecific facultative social parasitism in the paper wasp genus Mischocyttarus Saussure (Hymenoptera, Vespidae)

First report of interspecific facultative social parasitism in the paper wasp genus Mischocyttarus Saussure (Hymenoptera, Vespidae). Parasitism of colonies of the social wasp Mischocyttarus cerberus Ducke, 1918 by females of Mischocyttarus consimilis Zikán, 1949 was observed in a rural area of Dourados, state of Mato Grosso do Sul, Brazil. In all monitored cases, the invasion occurred in the pre-emergence colony stage, generally by a single female of M. consimilis. The period of establishment of the foreign female in the host colony was marked by antagonistic behaviors between the host female and the invasive. In general, the architecture of the parasitized nest was modified from the typical architecture of the host species nest.

Infestation and natural parasitism of aphids in single and mixed pastures of black oats and ryegrass

Some species of aphids are major pests on cereal crops and grass pastures. Usually these pests are not adequately controlled in pasture lands that become sources of aphid infestations to cereal crops. The dynamics of aphids and the incidence of natural enemies are less known in pasture systems than in cereal fields. The objective of this work was to assess the aphid infestation and natural aphid parasitism in different pasture composition. Three hypotheses were tested: 1- the aphid species composition in pastures may vary according to the cereal species in the field; 2- the mixture of two plant species can modify the amount and diversity of aphids; 3- the plant species composition of pasture fields influences the parasitism of aphids. Empirical data were obtained from three Poaceae fields: black oats (Avena strigosa L.), ryegrass (Lolium multiflorum L.), and a mixed field of black oats and ryegrass. The most abundant aphid species was Rhopalosiphum padi followed by Sitobion avenae. Plant species composition increases the amount and the parasitism rates of aphids. The mixture of heavily infested black oats with a poorly infested ryegrass resulted in reduction of aphid infestation in comparison with heavily-infested single plant species field. This is possible because the conditions are favorable for the development of parasitoid populations. Aphidius colemani was the main parasitoid found in these areas.

Natural parasitism of Diaphorina citri Kuwayama (Hemiptera, Psyllidae) nymphs by Tamarixia radiata Waterston (Hymenoptera, Eulophidae) in São Paulo orange groves

The psyllid Diaphorina citri Kuwayama 1908 has become the main citrus pest species in the state of São Paulo, Brazil, after the introduction of the huanglongbing or citrus greening. This study evaluated the parasitism of 3rd, 4th and 5th instar D. citri nymphs by Tamarixia radiata (Waterston, 1922) in citrus groves under a regimen of regular insecticide applications in ten producing regions: Araraquara, Barretos, Bauru, Botucatu, Franca, Itapetininga, Jaú, Limeira, Lins and São João da Boa Vista. Sixty-nine samples of new branches infested with nymphs of D. citri were collected from 2005 to 2008 in orange groves ranging from 1 to 20 years old, of the varieties Hamlin, Pera, Valencia and Natal. The parasitoid T. radiata is widely distributed in São Paulo orange groves, and was identified in 50 (72%) of the samples, showing a mean parasitism rate of 12.4%. The highest parasitism rate was observed in the "summer" (from January through March), with a mean of 25.7%. Nymphal parasitism was above 90% in two samples. The probable causes of the variations in parasitism of D. citri by T. radiata are discussed.

Parasitism by Campoletis flavicincta on Spodoptera frugiperda in corn

Parasitism by Campoletis flavicincta (Ashmead) (Hymenoptera: Ichneumonidae) on Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) and consequent reduction of production losses were evaluated on caged corn plants in the field. Treatments consisted of plots infested with 0 (control), 15 and 30 pairs of C. flavicincta with egg masses per cage and plot infested without cage and liberation of the parasitoid. Parasitoid release was done when S. frugiperda larvae were three-day-old. Fifty corn plants (40%) per plot were collected seven days after infestation and S. frugiperda larvae present were reared in glass cups on an artificial diet. Number of S. frugiperda larvae was reduced by C. flavicincta but mortality of the pest and parasitoid sex ratio in laboratory were similar among treatments. Total progeny and female production from collected larvae were similar among densities of released parasitoid. Parasitism rate was higher on 30 than on 15 pairs of C. flavicincta. Damage on corn plants at seven and 14 days after S. frugiperda infestation had similar grades at 0, 15 or 30 C. flavicincta pairs and higher values than the plots without cage. Damage by S. frugiperda was lower at 30 C. flavicincta pairs after 21 days of infestation. Final stand, stand reduction by plant death and corn productivity were similar among treatments.

Parasitism of the mite Acarophenax lacunatus on Tribolium castaneum

The objective of this work was to assess the parasitism potential of Acarophenax lacunatus (Cross & Krantz) on Tribolium castaneum (Herbst). The experimental units encompassed Petri dishes containing 25 g of wheat infested with 20 adults of this beetle species. After seven days of infestation, different mite densities (0, 2, 4, 6, 8 and 10 females) were inoculated into the Petri dishes. The increase in mite density led to a linear increase in parasitism, and a consequent reduction in populations of this insect. It is possible to use this mite species in the biological control of T. castaneum.

Tissue culture parameters in sweet orange cultivars

The objective of this work was to establish tissue culture parameters for gene transfer in sweet orange cultivars. Epicotyl explants with different ages were cultured with 6-benzylaminopurine (BAP), kanamycin and hygromycin. Shoots were cultured with alpha-naphthaleneacetic acid (NAA) alone or in combination with indole-3-butyric acid (IBA). The requirement of BAP for shoot development was genotype-specific. Epicotyl explants from 35-day-old seedlings produced significantly more shoots per explant in 'Pêra'. Kanamycin inhibited shoot regeneration for the most cultivars. The percentage of shoots that produced roots in 'Pêra' was significantly higher in medium with NAA and IBA than with NAA alone.

Growth regulators, culture media and antibiotics in the in vitro shoot regeneration from mature tissue of citrus cultivars

The objective of this study was to evaluate the effects of 6-benzylaminopurine (BAP) and α-naphthaleneacetic acid (NAA) combinations, basal media and beta-lactam antibiotics on in vitro organogenesis from mature stem segments of 'Pêra', 'Valência' and 'Bahia' sweet oranges and 'Cravo' rangpur lime. For induction of shoot regeneration, the segments of the four cultivars were placed on Murashige and Skoog (MS) medium containing the following BAP/NAA concentrations: 0.0/0.0; 0.25/0.0; 0.25/0.25; 0.5/0.0; 0.5/0.5; 1.0/0.0; 2.0/0.0; 2.0/0.25; 2.0/0.5; and 2.0/1.0 mg L-1. In order to test the influence of the culture media on shoot-bud induction, (MS), Murashige and Tucker (MT), and woody plant medium (WPM) formulations were evaluated, associated with the best combination of plant growth regulators obtained in the previous experiment. The influence of four beta-lactam antibiotics (timentin, cefotaxime sodium salt, meropenem trihydrate and augmentin) on shoot regeneration was determined. Better regeneration responses were achieved when internodal segments were cultured onto MS-based medium with 500 mg L-1 cefotaxime with the following BAP/NAA concentrations: 0.5 + 0.25 mg L-1 for 'Cravo', 1.0 + 0.25 mg L-1 for 'Valência' and 'Bahia', and 1.0 + 0.5 mg L-1 for 'Pêra'. Genotype, growth regulators, basal media and beta-lactam antibiotics affect the morphogenetic response in mature tissues of citrus.

The avocado fruit borer, Stenoma catenifer (wals.) (Lepidoptera: elachistidae): egg and damage distribution and parasitism

The avocado fruit borer, Stenoma catenifer (Wals.) has been a limiting factor in growing avocados over the last years in many Brazilian states. This is a result of the lack of safe and feasible management practices to minimize the fruit borer damage. The aim of this study was to obtain information on the pest biology and ecology as well as on the role of natural enemies to define strategies to control the pest. Samples were taken biweekly and consisted of 20 fruits collected randomly (10 from the upper half and 10 from the lower half of the plant) in ten plants, cv. Margarida, in a commercial avocado grove in Arapongas and Cambé regions, PR, from October/2001 to September/2002. Laboratory determinations of the percentage of damaged fruit per plant region, location and number of bored fruit sites, and the number and location of the fruit borer eggs, including parasitized ones, were performed. The results showed that S. catenifer preferred to oviposit and attack fruits located on the upper half of the trees. The majority of the eggs were laid on the fruit pedicel whereas the damage was mainly located on the lower half of the fruits. Trichogrammatids were the most constant and abundant parasitoids found in both localities throughout the study period.