Histone acetylation and methylation marks in chromatin of Panstrongylus megistus (Hemiptera,Reduviidae)

Panstrongylus megistus, a potential vector of Chagas disease, currently occupies a wider geographic distribution in Brazil than Triatoma infestans, another member of the hemipteran Reduviidae family and a vector of the same disease. A small heterochromatic body (chromocenter) formed by the Y chromosome is evident in the somatic cells of P. megistus, differing in size and chromosome type contribution from the well-studied chromocenters present in T. infestans. While the overall distribution of histone epigenetic marks differ when comparing the heterochromatin and euchromatin territories in T. infestans, no similar data have been established for other hemipteran reduviids, including P. megistus. In the present work, histone acetylation and methylation marks were investigated in cells of Malpighian tubules of P. megistus 5th instar nymphs using immunocytochemical assays and compared to previously published data for T. infestans. Although similarities between these species were found regarding absence of acetylated H3K9, H4K8 and H4K16, and H3K9me and H3K9me₂ in the chromocenter, presence of these marks in euchromatin, and presence of H3K9me₃ in the chromocenter, no intimate association of acetylated H4K8 and 18S rDNA was revealed in the chromocenter of P. megistus. The elevated abundance of H3K9me₂ marks at the nuclear periphery in P. megistus cells, differing from data for T. infestans, is suggested to reflect differences in the interaction of lamina-associated chromatin domains with the nuclear lamina, methyl-transferase modulation and/or association with the last DNA endoreplication step in 5th instar nymphs, which is a matter for further investigation.     

Flight initiation of Triatoma infestans (Hemiptera: Reduviidae) under natural climatic conditions

Flight dispersal of Triatoma infestans Klug is probably the most important mechanism for house reinfestation at a village scale after residual spraying with insecticides. The aim of the current study was to estimate the flight initiation probability of field-collected T. infestans and to assess how this probability was affected by sex, adult age, partial bloodmeal, and the presence of a host inaccessible for feeding. Four experimental series, each consisting of three to six consecutive nights and repeated measurements of flight initiation on each individually marked bug, were carried out in experimental huts inside closed cages under natural climatic conditions. We demonstrate that flight initiation probability of T. infestans is much higher than previously reported, responds to temperature in a sigmoid manner, and is higher in females than males, and that the frequency distribution of the number of flights per individual is highly aggregated in female and male bugs. The age of adults had strong effects on flight initiation, whereas the presence of an inaccessible host and a partial bloodmeal exerted no significant effects in models controlling for the effects of bug weight-to-length ratio. The high flight potential found is consistent with the rapid changes in reinfestation patterns observed in the field. The present estimates of flight probabilities and the identification of factors modifying them provide essential knowledge for modeling reinfestation patterns and for improving control strategies of T.     

组蛋白化学修饰改变对c-Myb结合的影响及其在职业性苯中毒患者造血损伤中的作用

 目的:研究职业性苯中毒造血损伤患者中与拓扑异构酶Ⅱα启动子调控因子c-Myb结合的组蛋白化学修饰改变, 证实组蛋白乙酰化修饰水平改变在职业性苯中毒造血损伤中发挥一定的作用。方法:25例职业性苯中毒再生障碍性贫血患者为病例组,25例正常人为对照组,提取骨髓单个核细胞,用染色质免疫沉淀(ChIP)探讨与c-Myb结合的组蛋白乙酰化和甲基化水平的改变,RT-PCR法检测c-Myb的mRNA表达水平,组蛋白去乙酰化酶(HDAC)试剂盒检测HDAC活性的变化。结果:与正常对照组相比,职业性苯中毒再生障碍性贫血患者c-Myb与乙酰化组蛋白H4、H3结合的水平下降(P<0.01), 而与甲基化组蛋白H3K4和H3K9结合的水平无明显改变,差异无统计学显著性。与正常对照组相比,职业性苯中毒再生障碍性贫血患者c-Myb的mRNA表达水平降低,HDAC活性明显升高,差异均有统计学显著性(P<0.05)。结论:拓扑异构酶Ⅱα启动子调控因子c-Myb可能通过组蛋白乙酰化修饰的改变在职业性苯中毒造血损伤中发挥作用。     

Contribution of AT-, GC-, and methylated cytidine-rich DNA to chromatin composition in Malpighian tubule cell nuclei of Panstrongylus megistus (Hemiptera, Reduviidae)

The Malpighian tubule cell nuclei of male Panstrongylus megistus, a vector of Chagas disease, contain one chromocenter, which is composed solely of the Y chromosome. Considering that different chromosomes contribute to the composition of chromocenters in different triatomini species, the aim of this study was to determine the contribution of AT-, GC-, and methylated cytidine-rich DNA in the chromocenter as well as in euchromatin of Malpighian tubule cell nuclei of P. megistus in comparison with published data for Triatoma infestans. Staining with 4′,6-diamidino-2-phenylindole/actinomycin D and chromomycin A₃/distamycin, immunodetection of 5-methylcytidine and AgNOR test were used. The results revealed AT-rich/GC-poor DNA in the male chromocenter, but equally distributed AT and GC DNA sequences in male and female euchromatin, like in T. infestans. Accumulation of argyrophilic proteins encircling the chromocenter did not always correlate with that of GC-rich DNA. Methylated DNA identified by immunodetection was found sparsely distributed in the euchromatin of both sexes and at some points around the chromocenter edge, but it could not be considered responsible for chromatin condensation in the chromocenter, like in T. infestans. However, unlike in T. infestans, no correlation between the chromocenter AT-rich DNA and nucleolus organizing region (NOR) DNA was found in P. megistus.     

Action of the saliva of Triatoma infestans (Heteroptera: Reduviidae) on sodium channels

Saliva of Triatoma infestans (Klug) produced a progressive reduction in the amplitude of the compound action potential recorded from rat sciatic nerve. The saliva also inhibited the Na+ current on GH3 cells. The data demonstrate that the saliva of T. infestans has an inhibitory effect on Na+ channels. We conclude that this effect may decrease the generation and conduction of nerve action potential, thereby decreasing the sensitivity of the region in which the insect probes, in a manner similar to that of local anesthetics. This study demonstrates such activity in the saliva of hematophagous insects. The adaptive value of this activity is clear, because the quantity of blood obtained by triatomines is limited by the irritation caused during the feeding process.     

Influence of the blood meal source on the development of Triatoma infestans, Triatoma brasiliensis, Triatoma sordida, and Triatoma pseudomaculata (Heteroptera, Reduviidae)

The objective of this study was to determine the influence of the blood meal source on the life cycle and reproductive development of female Triatoma infestans (Klug, 1834), Triatoma brasiliensis Neiva, 1911, Triatoma sordida (Stal, 1859), and Triatoma pseudomaculata Corrga & Espfinola, 1964. In all triatomine species studied the life cycle was shorter for the groups fed on mice than for those fed on pigeons, the range of differences being between 1.5 times (T pseudomaculata and T. infestans) and 2.4 times (T brasiliensis). The mortality rate of nymphs during the life cycle tended to be greater in insects fed on pigeons than in those fed on mice, the differences for T. brasiliensis being statistically significant. Females of T sordida and T pseudomaculata had a greater fecundity than those of T. infestans and T. brasiliensis independently of the blood meal source. The differences of fecundity observed probably reflect differences in the availability of blood in the silvatic ecotopes of these species, meals being more frequent for T. infestans and T brasiliensis, which live at high densities in association with rodents in highly stable ecotopes. Because T. sordida and T. pseudomaculata live in more unstable ecotopes with fewer sources of blood they form small sparse colonies and invest more energy in reproduction than maintenance.     

Microgeographic spatial structuring of Triatoma infestans (Hemiptera: Reduviidae) populations using wing geometric morphometry in the Argentine Chaco

We investigated the occurrence of spatial structuring in Triatoma infestans (KLug) (Hemiptera: Reduviidae) populations 12 yr after the last community-wide insecticide spraying campaign in rural Pampa del Indio, in the Gran Chaco of northeastern Argentina. In total, 172 male and 149 female right wings collected at 16 georeferenced sites with at least 10 individuals of the same sex were analyzed using geometric morphometry. Mean female body length and wing centroid size (CS) were significantly larger than for males. Log-transformed CS and length were significantly and positively correlated both for males and females. Males collected in domiciles had significantly smaller CS than those collected in peridomestic structures both closed (kitchens or storerooms) or open (chicken coops), in agreement with our previous results elsewhere in the dry Argentine Chaco. Female wing CS was not significantly different between ecotopes. Wing shape analyses showed the occurrence of significant geographic structuring in males and females combined and in males only. Male wings showed a strong association between Mahalanobis distance and geographic distance. In general, Mahalanobis distances were significantly different between collection sites located > 4 km apart. For collection sites located < 4 km apart, the greater the geographic distance the larger the difference in wing shape variables. Among females, only a partial correspondence between geographic groups and Mahalanobis distances was recorded. The strong spatial structuring found in T. infestans populations may be useful for the identification of putative reinfestation sources after vector control interventions.     

The effects of sodium butyrate,an inhibitor of histone deacetylase,on the cocaine- and sucrose-maintained self-administration in rats

In order to substantiate the concept that cocaine behavioral effects may be influenced by histone modification, rats were trained to self-administer cocaine intravenously (0.75 mg/(kg injection)), and were systemically pretreated with sodium butyrate (NaBu), a potent histone deacetylase inhibitor, before the test session during the maintenance phase. The effect of NaBu on a control reinforcer (sucrose)-induced self-administration was also assessed. NaBu (100–200 mg/kg) was inactive in altering the cocaine (0.75 mg/(kg injection))-maintained responding and at the highest dose (400 mg/kg) it did increase cocaine-induced lever presses during the maintenance phase. On the other hand, sucrose-reinforcing potential was not altered when NaBu was given at the highest dose (400 mg/kg). These findings extend previous observations that changes in histone acetylation are relevant to cocaine-induced behavioral effects. Given that histone acetylase inhibitor enhances cocaine-induced behavioral plasticity, the therapeutic benefits of histone acetyltransferase inhibitors warrant further investigation in the experimental models of cocaine abuse.     

Biogeography of Triatoma sanguisuga (Hemiptera: Reduviidae) on two barrier islands off the coast of Georgia, United States

Thirty-three Triatoma sanguisuga (LeConte) adults and nymphs were collected during June and July 2009, at five sites on Cumberland Island and two sites on Sapelo Island, Georgia, to assess genetic diversity within and between sites. All but three specimens were found in a peridomestic habitat. The entire length (699 bp) of the cytochrome oxidase II mitochondrial gene was sequenced for each specimen. Twelve haplotypes were identified, nine from Cumberland Island and three from Sapelo Island. No haplotypes were shared between the two islands, indicating there is limited or no movement of gene flow between the islands. Phylogenetic relationships among the haplotypes were determined using both neighbor-joining and maximum parsimony analyses. The phylogenetic trees from both analyses were similar, with no distinct clades on either tree devoted to haplotypes from a single island. A haplotype network structure was determined using nested clade analysis, which produced two haplotype networks, one containing only specimens found on Cumberland Island. The second network included specimens from both islands, with the ancestral haplotype from Sapelo Island. This pilot study is the first to highlight triatomine populations in the southeastern United States using the cytochrome oxidase II mitochondrial gene, and indicates strong population structuring along the Georgia Coast.     

丁酸钠对卵巢癌细胞株SKOV-3表达H3K9Ac、H3K14Ac、H4K20TriMe蛋白的影响

目的观察不同浓度丁酸钠处理SKOV-3细胞后对H3K9Ac、H3K14Ac、H4K20TriMe蛋白表达的影响。方法在上皮性卵巢癌细胞株SKOV-3培养过程中给予不同浓度的丁酸钠处理，观察细胞生长情况，用western blot方法测定处理前后SKOV-3细胞中H3K9Ac、H3K14Ac、H4K20TriMe蛋白表达情况。结果①当丁酸钠浓度为4～16mmol／L时，对SKOV-3细胞体外生长均有明显的抑制作用。②丁酸钠可影响SKOV-3细胞的形态。③丁酸钠处理48h后H3K9Ac的表达明显增高，而H3K14Ac、H4K20TriMe蛋白表达无明显变化。结论①组蛋白去乙酰化酶抑制剂具有抗肿瘤作用。②去乙酰化酶抑制剂可通过逆转特异位点的组蛋白乙酰化而发挥抗肿瘤的作用，这可能与其上调一系列关键基因的表达有关。     

Importance of Triatoma pallidipennis (Hemiptera: Reduviidae) as a vector of Trypanosoma cruzi (Kinetoplastida: Trypanosomatidae) in the state of Morelos, Mexico, and possible ecotopes.

We performed a transversal-type epidemiological study in the state of Morelos, Mexico, to determine the presence of triatomines, their ecotopes, and importance in transmission of Trypanosoma cruzi Chagas. Sampling sites included domestic, peridomestic, and wild areas with collection based on the person per hour technique. We determined the entomological indices related to infestation, density, overcrowding, colonization, infection, and dispersion, which were used to calculate transmission risk. During the study, observations were made on the predominant building material, presence of cracks and illumination as factors fostering colonization. The most important results were related to infection indices, which were higher for domestic type triatomines (29%), whereas it was 4% for peridomestic sites, and 20% for sylvatic areas. The actual risk of human contact with the vector was of 0.51%, and the predominating ecotopes were stone heaps.     

Study on mammal (rat) of the neuro-muscular synapse function under hyperbaric conditions (11 ata): Effects of the curarization

Summary Under hyperbaric conditions (11 ata) obtained with normoxic O₂-N₂ mixtures spontaneous EMG activity disappears, as do reactions to noise, but this phenomenon is reversible after the substitution of Helium for Nitrogen in the mixture.Analysis of EMG responses to sciatic nerve excitation has revealed no difference between the EMG tracings recorded under normobaric pressure and those obtained under hyperbaric conditions (O₂-N₂ or O₂-He, 11 ata), and hyperbaric conditions do not seem to interfere with neuro-muscular synaptic transmission. Furthermore, the effect of Pavulon (an antidepolarising, acetyl-cholino-competitive curare-mimetic drug) is similar under normal and hyperbaric conditions: hyperbaria changes neither the onset of neuro-muscular blockage nor its intensity or duration. The absence of a specific effect on synapse function of a change in the diluting gas from nitrogen to helium suggests that there was no change in post-synaptic receptor function. This result is not in accordance with the hypothesis that inert gas pressures of less than 10 ata modify molecular structures particularly at the neuro-muscular synapse level.     

Effects of sugar cross-linking agents and thermal treatment on the culture of fibroblasts in vitro on a (PEG/chitosan) membrane

The influences of sugar and a thermal treatment process on the properties of a PEG/chitosan membrane were investigated in this study. With increasing thermal treatment temperature, the cross-linking density was increased and the crystal structure was distorted in the sugar-mediated polyblend. The coloration of the samples intensified from yellow or brown to dark brown during the heat exposure, indicating that a Schiff base was formed. The presence of cross-linking was determined from the FTIR spectrum, a solubility test, and water uptake. The C N bonding shown in the FTIR spectrum indicates that a Maillard reaction occurred in the sugar-mediated polyblend. The water uptake ability of the samples tested was in the following sequence: sucrose > glucose > D-fructose, which was inverse to the trend of the cross-linking density. The compatibility of the polyblend and the sugar-mediated polyblend with fibroblasts was demonstrated. The thermal treatment has an insignificant effect on cell attachment on chitosan and the other polyblends, but different types of sugar and the cross-linking density changed the cell behavior. Consequently, chitosan/PEG6K cross-linked with sucrose at a concentration of 10 wt% and 120°C thermal treatment shows potential for biomedical applications.     

Effects of sugar cross-linking agents and thermal treatment on the culture of fibroblasts in vitro on a (PEG/chitosan) membrane

The influences of sugar and a thermal treatment process on the properties of a PEG/chitosan membrane were investigated in this study. With increasing thermal treatment temperature, the cross-linking density was increased and the crystal structure was distorted in the sugar-mediated polyblend. The coloration of the samples intensified from yellow or brown to dark brown during the heat exposure, indicating that a Schiff base was formed. The presence of cross-linking was determined from the FTIR spectrum, a solubility test, and water uptake. The C=N bonding shown in the FTIR spectrum indicates that a Maillard reaction occurred in the sugar-mediated polyblend. The water uptake ability of the samples tested was in the following sequence: sucrose > glucose > D-fructose, which was inverse to the trend of the cross-linking density. The compatibility of the polyblend and the sugar-mediated polyblend with fibroblasts was demonstrated. The thermal treatment has an insignificant effect on cell attachment on chitosan and the other polyblends, but different types of sugar and the cross-linking density changed the cell behavior. Consequently, chitosan/PEG6K cross-linked with sucrose at a concentration of 10 wt% and 120 degrees C thermal treatment shows potential for biomedical applications.     

Effects of Tacrolimus (FK506) on the Development of Osteonecrosis in a Rabbit Model

The present study examined the effects of tacrolimus (FK506) on the development of osteonecrosis in rabbits. In Experiment A, rabbits were given FK506, and also given a single dose of steroid. Control rabbits were given the same dose of steroid only. In Experiment B, rabbits were given FK506 and a reduced dose of steroid. The results showed that addition of FK506 did not change the number of rabbits with osteonecrosis when an identical steroid dose was given. When the steroid dose was reduced, the osteonecrosis incidence significantly decreased (p < 0.01). These results suggest that the clinically reported decrease in the osteonecrosis incidence following the introduction of FK506 is most likely attributable to the lower doses of steroids.     

Effects of temperature and white sucker (Catostomus commersoni) serum supplement on the in vitro multiplication of Cryptobia catostomi in cell-free culture medium

 Cryptobia catostomi, a non-pathogenic haemoflagellate of white suckers (Catostomus commersoni) multiplied rapidly in modified TDL-15 medium supplemented with 10% fetal bovine serum and 1% heat-inactivated white sucker serum (WSS) at 10°C and 18°C. The numbers of C. catostomi counted were significantly higher in cultures incubated at 10°C than in those incubated at 18°C beginning at 3 weeks post-incubation. The culture forms (from the eighth subculture at 9 months after isolation) were morphologically similar to blood forms and were infective to laboratory-raised white suckers. The parasite survived for about 4 weeks in the medium without WSS at 18°C. The present study indicates that WSS supplement supports the in vitro multiplication of C. catostomi and that its multiplication is temperature-dependent. Received: 24 May 1995 / Accepted: 18 October 1995     

螺内酯、氯沙坦及两者合用对急性心肌梗死大鼠心肌胶原重建、醛固酮合成酶基因及胶原mRNA表达的影响

目的：对比螺内酯、氯沙坦及两者合用对急性心肌梗死(AMI) 大鼠左心室重构的影响。方法:通过结扎冠状动脉左前降支诱导大鼠心肌梗死，心肌梗死术后存活48 h的大鼠随机分成①假手术组（sham组）和心肌梗死组。心肌梗死组随机分为：②AMI对照组（AMI组，自来水2 mL/d灌胃）、③螺内酯组（螺内酯20 mg·kg^-1·d^-1灌胃）、④氯沙坦组（氯沙坦50 mg·kg^-1·d^-1灌胃）、⑤合用组（螺内酯20 mg·kg^-1·d^-1+氯沙坦50 mg·kg^-1·d^-1灌胃）。观察治疗后第2周、第6周心肌胶原各项指标、非梗死区心肌醛固酮合成酶（CYP11B₂）mRNA、Ⅰ型胶原mRNA及Ⅲ型胶原mRNA的含量。结果:AMI对照组非梗死区胶原含量、梗死区胶原含量、Ⅰ/Ⅲ胶原比值、PCNA阳性细胞数、CYP11B₂ mRNA水平、Ⅰ型胶原mRNA水平、Ⅲ型胶原mRNA水平均显著高于sham组（均P<0.01）。螺内酯组、氯沙坦组及合用组第2周、第6周以上各指标除梗死区胶原含量外均显著低于AMI对照组（均P<0.01）。氯沙坦组以上各指标在第2周、第6周与螺内酯组相比均无显著差异（均P>0.05）。合用组以上各指标除梗死区胶原含量外在第6周均显著低于螺内酯组及氯沙坦组（均P<0.01） 。结论：螺内酯、氯沙坦及其联合治疗均可显著降低非梗死区心肌胶原沉积及Ⅰ/Ⅲ型胶原比值，抑制胶原的增生，两种药物合用效果优于螺内酯或氯沙坦单用。