Progresos y retos de la Toxicología Genética / Progress and challenges of Genetic Toxicology

Resumen: Esta revisión resume los principales avances de la citogenética y proporciona una perspectiva sobre el futuro de la toxicología genética, desde el pasado, presente y futuro, tanto desde el punto de vista genético como epigenético. Los principios de la citogenética clásica han evolucionado con el tiempo, interactuando con enfoques de toxicología para dar lugar a la toxicología genética o mutagénesis ambiental. Actualmente, están surgiendo estudios toxicogenómicos basados en estudios de toxicología genética estándar, y uno de los principales objetivos de la toxicogenómica es detectar relaciones entre cambios en la expresión génica global y criterios de valoración toxicológicos, con el fin de comprender el papel de las interacciones gen-ambiente en la enfermedad. Para alcanzar este objetivo, la toxicogenómica combina la toxicología, la genética, tecnologías de perfiles moleculares de alto rendimiento como la transcriptómica, proteómica, metabolómica y la bioinformática. En este campo, muchas limitaciones restringen el papel de los nuevos hallazgos y enfoques. Por ejemplo, el costo de las nuevas tecnologías; sin embargo, su aplicación contribuirá a una mejor comprensión de las interacciones gen-ambiente y de esta manera, establecer políticas orientadas a prevenir riesgos para la salud, para que se viva una vida más saludable en un ambiente más favorable. (AU)

This review summarizes the main advances of cytogenetic and provides a perspective on the future of genetic toxicology, reviewing from past, present, and future, both genetics and epigenetic point of view. The principles of classical cytogenetics have evolved over time, interacting with toxicology approaches to give rise to genetic toxicology or environmental mutagenesis. Currently, toxicogenomic studies are emerging based on standard genetic toxicology studies, and one major goal of toxicogenomic is to detect relationships between changes in global gene expression and toxicological endpoints, in order to understand the role of gene-environment interactions in disease. To reach this goal, toxicogenomics combines toxicology, genetic, with genomics or other high throughput molecular profiling technologies such as transcriptomics, proteomics, metabolomics, and bioinformatics. In this field, many limitations are restricting the role of the novel findings and approaches. For example, the cost of new technologies; however, its application will contribute to a better understanding of gene-environment interactions and in this way, establish policies aimed at preventing health risks, so that a healthier life is lived in a friendlier environment. (AU)

3-Methyl-2-benzothiazolinone hydrazone and 3-dimethylamino benzoic acid as substrates for the development of polyphenoloxidase and phenoloxidase activity by zymograms.

In the present study, a sequential staining process of polyphenoloxidase and phenoloxidase enzymes was designed by the zymography technique. As a first step, electrophoresis was carried out under native conditions, and later, first staining was carried out with a revealing solution of 3-methyl-2-benzothiazoline hydrazone (MBTH)-3-dimethylamino benzoic acid (DMAB) that allowed the visualization of polyphenoloxidase enzymes, and later and using the same gel, we proceeded to the differential staining of phenoloxidase, adding a solution of H2O2. The technique was standardized using commercial enzymes of laccase (T. versicolor) and horseradish. The technique was used to identify polyphenoloxidases (laccases) and phenoloxidases (lignin peroxidase) of crude extracts obtained from the growth of the basidiomycete Lentinus strigosus on Pinus radiata. The technique showed great sensitivity to detect the different enzymatic activities (1.56 Activity Unit/mL minimum) in the same gel without interference between the enzymes and the solutions used. On the other hand, the efficiency of the technique was compared with the substrates that are commonly used for the detection of this type of activities such as 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) and guaiacol, observing greater sensitivity and minimal interference, so that the present method will allow in the same gel, and visualize polyphenoloxidase and phenoloxidase activities simultaneously facilitating expression studies.

Isolation and Selection of Streptomyces Species from Semi-arid Agricultural Soils and Their Potential as Producers of Xylanases and Cellulases.

The Mezquital Valley (MV), Mexico, is a semi-arid region whose main economic activity is agriculture, this zone is characterized by the use of wastewater for crop irrigation. This condition has increased the amount nutrients in soils, organic carbon content and native microorganisms. The Streptomyces species are a group of saprophytic bacteria that represent between 20 and 60% of the total microbial population in soils, capable of producing metabolites of commercial importance. In this work, Streptomyces species were isolated from agricultural soils of the MV and was evaluated the production of endoglucanases (CMCase) and xylanases (Xyl) in Solid-State Cultivation (SSC). From soil samples, 73 possible strains of Streptomyces species were isolated for their ability to produce CMCase and Xyl in SSC. The study also included its characterization by morphological characteristics. Of the isolated microorganisms, 38 strains were selected as strong enzyme producers according to the measurement of the halo generated in plate and by growth on barley straw as only carbon source. Two different sizes of barley straw particle were tested, finding that the greatest enzymatic activity was observed in particle size 12. Three strains of Streptomyces species were chosen which presented the best catalytic capacities, a maximum of 100.69 AU Xyl/gram dry matter (gdm), 82 AU Xyl/gdm and 26.02 AU CMCase/gdm for strains 30, 28 and 12, respectively. The strains were identified by ribosomal gen16s sequence and identified as S. flavogriseus, S. virginiae and S. griseoaurantiacus. It is the first report of endogluconase and xylanolytic activity by S. virginiae isolated from a semi-arid soil.

Use of barley straw as a support for the production of conidiospores of Trichoderma harzianum.

In this work was to evaluate the conidiospores production of Trichoderma harzianum using barley straw as substrate. Four growth conditions were used; washed and unwashed barley straw and washed and unwashed barley straw supplemented with mineral salts. The highest spore production was observed when washed barley straw supplemented with mineral salts with 1.56 × 1010 conidiospores/gram of dry matter (gdm) at 216 h of cultivation was used. The effect of substrate moisture on spore production was studied, three initial moisture levels of the substrate were tested and it was observed that a humidity of 80 % of the substrate improves the production of conidiospores reaching a concentration of 2.35 × 1010 conidiospores/gdm at 136 h. Finally, conidiospores viability was evaluated for 12 months by keeping them on the conidia and substrate, and viability of 71 % of the conidiospores was observed, so this maintenance method is an excellent means of conserving the conidiospores viability.

A test method for evaluating the thermal environment of underground coal mine refuge alternatives.

Since 2009, the Mine Safety and Health Administration (MSHA) has required mines to install refuge alternatives (RAs) in underground coal mines. One of the biggest concerns with occupied RAs is the possible severity of the resulting thermal environment. In 30 CFR 7.504, the maximum allowable apparent temperature (AT) for an occupied RA is specified as 35 °C (95 °F). Manufacturers must conduct heat/humidity tests to demonstrate that their RAs meet the 35 °C (95 °F) AT limit. For these tests, heat input devices are used to input the metabolic heat of actual miners. A wide variety of test methods, sensors, and heat input devices could be used when conducting such tests. Since 2012, the National Institute for Occupational Safety and Health (NIOSH) has conducted over thirty 96-hour heat/humidity tests on four different RAs. This paper discusses the test equipment and procedures used during these investigations. This information is useful for RA manufacturers conducting RA heat/humidity tests, for other researchers investigating RA heat/humidity buildup, and for those who need to assess the thermal environment of any confined space where people may be trapped or are seeking refuge.

Intestinal cell migration damage induced by enteropathogenic Escherichia coli strains.

Epithelial cell migration is an essential response to enteric pathogens such as enteropathogenic Escherichia coli (EPEC). This study aimed to investigate the effects of EPEC infection on intestinal epithelial cell migration in vitro, as well as the involvement of type III secretion system (T3SS) and Rho GTPases. Crypt intestinal epithelial cells (IEC-6) were infected with EPEC strains (E2348/69, ΔescF, and the LDI001 strain isolated from a malnourished Brazilian child) and commensal E. coli HS. Wound migration and cell death assays were performed at different time-points. Transcription and expression of Rho GTPases were evaluated using real-time PCR and western blotting. Overall, EPEC E2348/69 reduced migration and increased apoptosis and necrosis levels compared to EPEC LDI001 and E. coli HS strains. Moreover, EPEC LDI001 impaired cell migration at a higher level than E. coli HS and increased necrosis after 24 hours compared to the control group. The different profiles of virulence genes between the two wild-type EPEC strains, characterized by the absence of espL and nleE genes in the LDI001, might explain the phenotypic results, playing significant roles on cell migration impairment and cell death-related events. Moreover, the type III secretion system is determinant for the inhibition of intestinal epithelial cell migration by EPEC 2348/69, as its deletion prevented the effect. Active Rac1 concentrations were increased in E2348/69 and LDI001-infected cells, while the T3SS-deficient strain did not demonstrate this activation. This study contributes with valuable insight to characterize the mechanisms involved in the impairment of intestinal cell migration induced by EPEC.

Intestinal cell migration damage induced by enteropathogenic Escherichia coli strains

Epithelial cell migration is an essential response to enteric pathogens such as enteropathogenic Escherichia coli (EPEC). This study aimed to investigate the effects of EPEC infection on intestinal epithelial cell migration in vitro, as well as the involvement of type III secretion system (T3SS) and Rho GTPases. Crypt intestinal epithelial cells (IEC-6) were infected with EPEC strains (E2348/69, ΔescF, and the LDI001 strain isolated from a malnourished Brazilian child) and commensal E. coli HS. Wound migration and cell death assays were performed at different time-points. Transcription and expression of Rho GTPases were evaluated using real-time PCR and western blotting. Overall, EPEC E2348/69 reduced migration and increased apoptosis and necrosis levels compared to EPEC LDI001 and E. coli HS strains. Moreover, EPEC LDI001 impaired cell migration at a higher level than E. coli HS and increased necrosis after 24 hours compared to the control group. The different profiles of virulence genes between the two wild-type EPEC strains, characterized by the absence of espL and nleE genes in the LDI001, might explain the phenotypic results, playing significant roles on cell migration impairment and cell death-related events. Moreover, the type III secretion system is determinant for the inhibition of intestinal epithelial cell migration by EPEC 2348/69, as its deletion prevented the effect. Active Rac1 concentrations were increased in E2348/69 and LDI001-infected cells, while the T3SS-deficient strain did not demonstrate this activation. This study contributes with valuable insight to characterize the mechanisms involved in the impairment of intestinal cell migration induced by EPEC.

Addenbrooke's Cognitive Examination validation in Parkinson's disease.

BACKGROUND: There is a clear need for brief, sensitive and specific cognitive screening instruments in Parkinson's disease (PD). OBJECTIVES: To study Addenbrooke's Cognitive Examination (ACE) validity for cognitive assessment of PD patient's using the Mattis Dementia Rating Scale (MDRS) as reference method. A specific scale for cognitive evaluation in PD, in this instance the Scales for Outcomes of Parkinson's disease-Cognition (SCOPA-COG), as well as a general use scale the Mini-mental state examination (MMSE) were also studied for further correlation. METHODS: Forty-four PD patients were studied, of these 27 were males (61%), with a mean (SD) age of 69.5 (11.8) years, mean (SD) disease duration of 7.6 (6.4) years (range 1-25), mean (SD) total Unified Parkinson's Disease Rating Scale (UPDRS) score 37 (24) points, UPDRS III 16.5 (11.3) points. MDRS, ACE and SCOPA-COG scales were administered in random order. All patients remained in on-state during the study. RESULTS: Addenbrooke's Cognitive Examination correlated with SCOPA-COG (r = 0.93, P < 0.0001), and MDRS (r = 0.91 P < 0.0001) and also with MMSE (r = 0.84, P < 0.001). Area under the receiver-operating curve, taking MDRS as the reference test, was 0.97 [95% confidence interval (CI): 0.92-1.00] for ACE, 0.92 (95% CI: 0.83-1.00) for SCOPA-COG and 0.91 (95% CI: 0.83-1.00) for MMSE. Best cut-off value for ACE was 83 points [Sensitivity (Se) = 92%; Specificity (Sp) = 91%; Kappa concordance (K) = 0.79], 20 points for the SCOPA-COG (Se = 92%; Sp = 87%; K = 0.74) and 26 points for MMSE (Se = 61%; Sp = 100%; K = 0.69). CONCLUSION: Addenbrooke's Cognitive Examination appears to be a valid tool for dementia evaluation in PD, with a cut-off point which should probably be set at 83 points, displaying good correlation with both the scale specifically designed for cognitive deficits in PD namely SCOPA-COG, as well as with less specific tests such as MMSE.

Sífilis secundaria en cavidad oral: Reporte de dos casos / Oral secondary syphilis: Two cases report

La sífilis es una enfermedad infecciosa humana causada por una bacteria: el Treponema pallidum. La enfermedad es transmitida por contacto directo a través de lesiones durante el estadio primario y secundario, por vía transplacentaria intrauterina o a través del canal uterino; puede afectar cualquier órgano de la economía causando un número infinito de presentaciones clínicas. La sífilis secundaria cursa con manifestaciones mucocutáneas características y eventual sintomatología general. La presentación clínica de nuestros dos pacientes es singular ya que solo poseían lesiones en la cavidad oral. La respuesta al tratamiento instaurado fue buena.

Syphilis is a human infectious disease caused by the bacterium Treponema pallidum. The disease is transmitted by direct contact with a lesion during the primary or secondary stages, in utero by the transplacental route, or during delivery as the baby passes through an infected canal. The bacterium may infect any organ, causing an infinite number of clinical presentations. Secondary syphilis is characterized by mucocutaneous lesions, a flulike syndrome, and generalized adenopathy. Hepatosplenomegaly may be present. The oral mucosa is the second most frequent site of luetic lesions; the genital areas are the most frequent. In the oral cavity, the most characteristic lesion is a whitish mucosal patch, normally located on the lips, tongue, or palate, which is extremely contagious. The differential diagnosis of this lesion may include oral squamous carcinoma, leukoplakia, candidosis, lichen planus, and hairy oral leukoplakia. Definitive diagnosis is based on clinical information and completed by laboratory examinations even the biopsy can help us. With the diagnosis of secondary syphilis treatment with penicillin G benzathine must be started. We present two cases of secondary syphilis with oral lesions only; the first one, a man with macule covered with a whitish membrane on palate mucosa and a lateral neck adenopathy. The lesion had been present for three months. The second one, a woman with painful whitish mucosal patch since two weeks ago. No fever or flulike syndrome. Luetic serologic tests were positive in both cases and in the first one the biopsy showed a chronic inflammatory infiltrate. The drug of choice in the treatment of our patients was benzathine penicillin G.

Xantomas eruptivos: A propósito de dos casos familiares / Eruptive xanthomas: Two familial clinical cases

Se presentan dos pacientes de sexo masculino, familiares de primer grado, tabaquistas y etilistas severos, sin antecedentes patológicos conocidos. Ambos presentan en forma eruptiva la aparición de xantomas y uno de ellos una pancreatitis necrohemorrágica atribuida a su hipertrigliceridemia, complicación muy grave de este trastorno. Si bien los xantomas eruptivos no son muy frecuentes de observar, deben hacernos sospechar en una dislipidemia severa, confirmándola con una examen de laboratorio que pondrá de manifiesto una elevación significativa de los triglicéridos y frecuentemente alteración de los niveles de glucosa en sangre. Además, el estudio histopatológico de las lesiones mostrará macrófagos cargados de lípidos, de aspecto espumoso e infiltrado polimorfonuclear y mononuclear en dermis.

We report a case of two male patients, first-grade relatives, who are heavy drinkers and smokers but apparently have no pathological records. Both show eruptive xanthomas and one of them presents acute necrotic and hemorrhagic pancreatitis due to hypertriglyceridemia, a serious complication of this disorder. Despite the fact that eruptive xanthomas are not frequently observed, they should make us suspect an instance of severe dyslipidemia. In order to verify it, a laboratory test will show a dramatic raise of serum triglyceride levels and usual changes in the blood glucose levels. Moreover, a histopathologic study of the lesion will reveal macrophages full of lipids (foam cells) with polymorphonuclear and mononuclear infiltrate.

Nevo epidérmico inflamatorio lineal (NEVIL): Presentación en la edad adulta / Inflammatory linear verrucous epidermal nevus (ILVEN): Late onset disease

El NEVIL es la variedad inflamatoria del nevo epidérmico; es un tumor benigno hamartomatoso, que se distribuye siguiendo las líneas de Blaschko. Estas líneas representarían mosaicismos cutáneos del desarrollo embriológico. El NEVIL suele aparecer en la infancia. Son generalmente unilaterales y en ocasiones muy pruriginosos. El diagnóstico diferencial es frecuentemente dificultoso. Presentamos una paciente en la cual la manifestación de esta patología se produce en forma tardía, siendo esto poco frecuente. El tratamiento es un desafío, se han probado múltiples modalidades terapéuticas, con resultados en ocasiones desalentadores. La cirugía, puede utilizarse en lesiones de pequeño tamaño. Los tratamientos con luz láser podrían ser de utilidad.

The ILVEN is the inflammatory variety of epidermal nevi, benign hamartomatous tumor that distributed following Blaschko lines. These lines represent cutaneous mosaicism in embryologic development. The ILVEN usually appear in the infancy. Generally unilateral and occasionally is very pruriginous. The differential diagnosis is often difficult. We present a patient in which the manifestation of her disease is produced in late onset, being this infrequent. Management is a challenge, multiple therapeutic modalities have been tested, with discouraging results. Surgery can be utilized in small size lesions. Laser therapy could be of utility.

Paracoccidioidomicosis perianal asociada a lepra lepromatosa: Presentación de un caso clínico / Perianal paracoccidioidomycosis associated with lepromatous leprosy: A clinical case report

Se presenta el caso de un paciente alcoholista con una ulceración perianal y manifestaciones cutáneas de enfermedad de Hansen. La biopsia de la lesión perianal y otros estudios arribaron al diagnóstico de una forma diseminada de paracoccidioidomicosis, así como también las biopsias cutáneas y los estudios baciloscópicos fueron diagnósticos de lepra lepromatosa. La respuesta a la terapéutica fue satisfactoria con desaparición de las lesiones cutáneas. La disminución de la respuesta inmunológica celular genera un terreno propicio para la infección de estos gérmenes y al compartir área endémica la asociación entre ambas patologías puede ocurrir.

Lepra and Paracoccidioidomycosis are endemic diseases in Argentina. We report a case of a patient with an unusual perianal ulceration and cutaneous manifestations of Hansen's disease. The biopsy of perianal lesion and subsequent studies revealed a disseminated form of paracoccidioidomycosis, as well as skin biopsy and baciloscopic finding diagnostic of Lepromatous Leprosy. The main portal of entry of paracoccidioides is the lung. Hematogenous dissemination of the fungus may occur at this time, with the establishment of metastatic foci in any organ. Anal and perianal lesions are present only in 1.3 to 2.4% of the patients. The pathogenesis of anal lesions remains unclear, it may be secondary from a systemic or a local disease. The patient response to the therapeutic was notable, with disappearance of lesions up to the third month of started itraconazole orally 400 mg/day leading just atrophy scars in perianal areas. The treatment of Hansen's disease was made according to OMS guidelines for multibacillary disease.

Úlcera de lengua como presentación del Histoplasma capsulatum / Tongue ulceration as a presentation of Histoplasma capsulatum infection

La histoplasmosis diseminada progresiva es una enfermedad que se manifiesta como reactivación de una infección latente en pacientes inmunodeprimidos, especialmente en personas con déficit en la inmunidad celular. Existen formas agudas, subagudas y crónicas. Las lesiones focales, en especial úlceras mucocutáneas, predominan en la forma diseminada crónica. Reportamos el caso de una paciente con artritis reumatoidea, que controlaba su patología con fármacos antirreumáticos modificadores de la enfermedad (DMARD), la que consultó por úlcera de lengua como única manifestación de una histoplasmosis diseminada crónica. La histopatología fue compatible y el cultivo positivo para Histoplasma capsulatum. La serología para el HIV fue negativa. Existen pocos casos publicados de pacientes con esta localización atípica en forma aislada, en particular aquellos HIV negativos. El itraconazol y la anfotericina B son las dos drogas más utilizadas para tratar esta enfermedad. Los datos clínicos sobre los nuevos azoles, voriconazol y posaconazol son limitados.

The progressive disseminated histoplasmosis is a disease produced by reactivation of latent infection in immunocompromised host, specially in persons with defective cell-mediated immunity. There are acute, subacute and chronic forms in the progressive illness. Focal lesions, specially mucocutaneous ulcers, are most frequent in the chronic disseminated forms. We reported a patient with rheumatoid arthritis treated with disease modifying antirheumatic drug (DMARD), with an ulcer of the tongue as only clinical manifestation of a chronic disseminated histoplasmosis. The histopathology was compatible, and the culture was positive for Histoplasma capsulatum. The serology for the HIV was negative. There are few published cases of this isolated form, particularly in patients with HIV negative serological test. Itraconazole and amphotericin B are the most frequently drugs used for the treatment in this disease. Clinical data on the new azoles, voriconazole and posaconazole, are limited.

Porfiria cutánea tardía: Reporte de 5 casos / Porphyria cutanea tarda: Five cases report

La PCT es la más común de las porfirias. Es una fotodermatosis que resulta de la deficiencia de la UPD, enzima perteneciente a la vía de síntesis del hemo. Presentamos la evolución de cinco casos de PCT; cuatro de PCT familiar y uno de PCT esporádica. En dos de los pacientes pertenecientes al grupo de PCT tipo II, encontramos como factor de riesgo, el consumo de alcohol, y en la paciente con PCT tipo I se detectó serología positiva para VHC. Todos los pacientes fueron tratados con cloroquina y flebotomías repetidas. Rápidamente se detectó mejoría clínica y bioquímica. Se observó que la porfirinuria continuó en descenso aún luego de suspendida la terapéutica. Tres de los pacientes con PCT familiar persisten en remisión clínica y con ausenciade recaídas tras más de 10 años de seguimiento. Aconsejamos en pacientes que padecen PCT la búsqueda de factores asociados (VHC, HIV, genes de HH) y desencadenantes exógenos (consumo excesivo de alcohol, hierro en la dieta e ingesta de estrógenos) que de ser controlados o evitados, junto con el tratamiento oportuno, contribuyen a un satisfactorio control de la enfermedad.

The porphyria cutanea tarda is the most frequent porphyria, it is a photodermatosis secondary to uroporphyrinogen decarboxylase deficiency; this enzyme belongs to the haem synthesis pathway. We present on this paper the evolution of five cases of PCT, four of them with familiar type and one of them sporadic type. In two patients belonging to PCT type II, we found alcohol addiction as a serious risk, while on the other patients PCT type I we found HCV positive serology. All patients were treated with chloroquine and phlebotomies. We could observe a good response not only clinical but biochemical. We could also see that the porphyrins urinary level continued descending once the drug was withdrew. Three of the patients with familiar PCT remains in clinical remission without any relapses in ten years of control. We advice all the patients that suffer PCT the detection of associated factors such as HCV, HIV, HH genes and the avoidance of the exogenous triggering factors such as excessive intake of alcohol, dietary iron and estrogen intake. Taking these advices into account, together with the correct treatment every patient can control this disease positively or satisfactorily.

Hyperhemolytic transfusion reaction attributable to anti-Fy3 in a patient with sickle cell disease.

A case of hyperhemolytic transfusion reaction attributable to anti-Fy3 in a 30-year-oldAfricanAmerican woman with a history of sickle cell disease is reported. The patient was admitted for vaso-occlusive sickle cell crisis and received 4 units of packed RBCs secondary to worsening symptomatic anemia (Hb 5.0 g/dL). On admission, the patient's antibody screen and identification showed anti-V and anti-E, and her antibody history included anti-E,-C,-Jk(b),-N, -V,-S,-Sl(a), and a cold agglutinin with possible anti-I specificity. A DAT performed on her RBCs was negative. RBC units that lacked E, C, Jk(b), N,V, and S were transfused. Posttransfusion Hb was 8.9 g/dL. On day 10 she developed a fever of 103 degrees F, and on day 11 her Hb decreased to 6.4 g/dL. She complained of severe back pain and dark urine. In addition, she became hypertensive, tachycardic, and jaundiced. The DAT indicated the presence of IgG on the patient's RBCs. Anti-Fy3 was identified in the serum and eluate. During the next 24 hours, her Hb decreased to 2.4 g/dL. The LDH level was 1687 U/L, and her reticulocyte count was 2.6%. A delayed hemolytic transfusion reaction with hyperhemolysis secondary to anti-Fy3 was suspected and was successfully treated with IVIG and high-dose prednisone. To the best of our knowledge, this is the first published case of hyperhemolysis in sickle cell disease attributable to anti-Fy3.

Light quanta modulated characteristics of Ni uptake by Brassica juncea seedlings: the interdependence of plant metal concentration and biomass.

The relationships between the concentration of metal in the growth medium, Cs, the concentration of metal absorbed by the plant, Cp, and the total biomass achieved, M, all of which are factors relevant to the efficiency of metal uptake and tolerance by the plant, have been investigated via the physiological response of Brassica juncea seedlings to Ni stress. The factorial growth experiments treated the Ni concentration in agar medium and the diurnal light quanta as independently variable parameters. Observations included the evidence of light enhancement of Ni toxicity in the root, as well as at the whole-plant level. The shoot mass index possibly is an indicator of the amount of shoot metal sequestration in B. juncea, as are the logarithmic variation of Cp with Cs and the power-law dependence of M on Cp. The sum total of these observations indicates that, for the Ni accumulating plant B. juncea, the overall metabolic allocation to either growth or metal tolerance of the plant is important. Neither a rapid biomass increase nor a high metal absorbed concentration favored the removal of high metal mass from the medium. Rather, the plants with a moderate rate of biomass growth and a moderate absorbed metal concentration demonstrated the ability to remove the maximum mass of metal from the medium. The implication of these results as related to the extant model of phyoextraction efficiency is discussed.

Search for exotic baryons in 800 GeV pp-->pXi+/-piX reactions.

We report the results of a high-statistics, sensitive search for narrow baryon resonances decaying to Xi-pi-, Xi-pi+, Xi+pi-, and Xi+pi+. The only resonances observed are the well known Xi0(1530) and Xi0(1530). No evidence is found for the states near 1862 MeV, previously reported by NA49 [Phys. Rev. Lett. 92, 042003 (2003)]. At the 95% confidence level, we find the upper limit for the production of a Gaussian enhancement with sigma=7.6 MeV in the Xi-pi- effective mass spectrum to be 0.3% of the number of observed Xi0(1530)-->Xi-pi+. We find similarly restrictive upper limits for an enhancement at 1862 MeV in the Xi-pi+, Xi+pi-, and Xi+pi+ mass spectra.

Biological Behavior and Partial Molecular Characterization of Six Chilean Isolates of Plum pox virus.

Plum pox virus (PPV) strain D was first detected in Chile in 1992 infecting Prunus trees including peaches, nectarines, apricots, and plums. Since then, quarantine efforts have included periodic surveys in the central zone of the country, the main region for stone fruit production. This work describes the characterization of six PPV isolates from this area of Chile, using biological and molecular approaches. PPV isolates were introduced into Prunus tomentosa and Nicotiana benthamiana hosts by grafting and mechanical inoculation, respectively. Symptoms were evaluated by following the appearance of circular necrotic spots and mosaic in leaves of P. tomentosa and mosaic and some leaf deformation in N. benthamiana. Molecular analysis was carried out using reverse transcription-polymerase chain reaction, allowing the cloning and sequencing of 1.34-kb fragments corresponding to the 3' region of the replicase gene, the complete coat protein (CP) gene, and the 3' nontranslated region of the PPV genome. Evolutionary distance analysis of these nucleotide sequences and their deduced coat protein amino acid sequences grouped the six Chilean isolates among strain D isolates, with closest genetic distances to those of Central Germany and Poland. Representative sources of these isolates suggest that strain D could be the only type of PPV currently present in Chile.

Lambda(0) polarization in 800-GeV/cpp --> p(f)(Lambda0K+).

We report results from a study of Lambda(0) polarization in the exclusive reaction pp --> p(f)(Lambda0K+) at 800-GeV/c. We observe a dependence of the polarization on the Lambda0K+ invariant mass with large (+71%) positive polarization at small mass (1.63-GeV/c(2)) and large (-43%) negative polarization at large mass (2.75-GeV/c(2)). This observation confirms the result of the CERN ISR R608 experiment and extends the range over which the effect is observed. The strong dependence of the polarization on the Lambda0K+ invariant mass suggests that the origin of the polarization is closely related to the production dynamics of the diffractively produced Lambda0K+ system.