Frações de fósforo e atividade da fosfatase ácida em plantas de feijoeiro cultivadas em solos de várzea

Foi realizado um experimento em casa de vegetação do Departamento de Ciência do Solo da Universidade Federal de Lavras, com o objetivo de verificar a influência dos atributos de quatro solos de várzea sobre a distribuição de algumas frações de fósforo nas folhas de feijoeiro, determinar suas respectivas concentrações críticas e a relação dessas frações com a atividade da fosfatase ácida foliar e a relação entre a atividade da fosfatase ácida determinada "In vitro" e "in vivo". O delineamento experimental foi o inteiramente casualizado, em esquema fatorial 4 x 5 x 2, com quatro repetições, sendo quatro solos [Glei Húmico (GH), Orgânico (O), Aluvial (A) e Glei Pouco Húmico (GP)], cinco doses de P (75, 150, 300, 500 e 800 mg dm-3 de P) e dois níveis de calagem (sem e com). Cada parcela foi constituída por um vaso com três dm³, onde foram cultivadas três plantas de feijoeiro. Uma das plantas foi colhida no florescimento, determinando-se, nas folhas, as concentrações de P total (Pt), P total solúvel em ácido (Pts), P orgânico (Po) e P inorgânico solúvel em ácido (Pi). Nas demais plantas, colhidas no final do ciclo, foi avaliada a produção de grãos. Os níveis críticos das frações de P no feijoeiro cultivado nos solos GH, O, A e GP, sem calagem, foram, respectivamente: Pt = 2,3, 2,2, 2,0, e 1,3 mg g-1; Pts = 110, 67, 78 e 63; Po = 32, 19, 20 e 21 e Pi = 77, 47, 58 e 43 µg g-1. Com calagem, os níveis críticos respectivos foram: Pt = 2,8, 3,0, 3,5 e 4,2 mg g-1; Pts = 105, 96, 130 e 154; Po = 47, 38, 42 e 52 e Pi = 59, 58, 88 e 103 µg g-1. A atividade da fosfatase ácida não foi uma boa característica de diagnose nutricional de fósforo em condições de severa deficiência desse elemento.

Fertilidade de solos de Várzea do Sul de Minas Gerais para o cultivo do feijoeiro

Com o objetivo de caracterizar as limitações nutricionais no crescimento e rendimento de grãos de feijoeiro (Phaseolus vulgaris L.) cv. Carioca-MG, conduziu-se este experimento em casa de vegetação, com amostras (0-20 cm) de quatro solos de várzea, Glei Pouco Húmico (GP), Orgânico (O), Glei Húmico (GH) e Aluvial (A), coletadas no município de Lavras, MG. Foram realizados dois cultivos sucessivos em vasos com três dm³. O delineamento experimental foi o inteiramente casualizado, em esquema fatorial 13 x 4 (13 tratamentos x 4 solos), com três repetições. Os tratamentos foram baseados na técnica do elemento faltante (omitindo-se a calagem e cada um dos macros e micronutrientes). Os resultados revelaram, nos quatro solos, deficiências severas de B, P e K, cujas omissões promoveram reduções no crescimento e no rendimento de grãos a valores inferiores a 50% em relação ao tratamento completo (calcário + macros e micronutrientes). A deficiência de B foi tão severa que não permitiu a produção de grãos. As deficiências de N, S, Ca e Mg, embora menos severas, reduziram significativamente o crescimento e o rendimento da cultura. A calagem mostrou-se indispensável ao cultivo do feijoeiro nesses solos. A presença de Zn na composição do calcário reduziu a deficiência do micronutriente nos solos Glei Pouco Húmico, Orgânico e Húmico. Não houve efeito de Cu na produção da cultura.

Formas de fósforo em solos de várzea e biodisponibilidade para o feijoeiro

Realizou-se um experimento em casa de vegetação do Departamento de Ciência do Solo da Universidade Federal de Lavras, com o objetivo de verificar a influência da aplicação de calcário e de P em algumas formas de P em quatro solos de várzea cultivados com feijoeiro. O delineamento experimental utilizado foi o inteiramente casualizado, em esquema fatorial 4 x 5 x 2, com quatro repetições, a saber: quatro solos [Glei Húmico (GH), Glei Pouco Húmico (GP), Aluvial (A) e Orgânico (O)], cinco doses de P (75, 150, 300, 500 e 800 mg dm-3 de P) e dois níveis de calagem (sem e com). Os solos foram incubados em vasos, por 30 dias, com as respectivas doses de calcário, e por mais 150 dias, com as doses de P. No final desse período, foram coletadas amostras de solo para o fracionamento de P, e o restante foi cultivado com feijoeiro. Cada parcela foi constituída por um vaso com 3 dm³, em que foram cultivadas duas plantas até o final do ciclo. A calagem e a adubação fosfatada influenciaram as formas de P de maneira distinta nos solos de várzea estudados; exceto no solo Glei Pouco Húmico, as formas de P lábil, tanto na ausência quanto na presença de calagem, tiveram pouca participação no P total dos solos. Na presença da calagem, o P lábil foi a forma de P preferencialmente absorvida pelas plantas de feijoeiro.

Polimorfismo no gene GH1-PstI associado a características corporais de linhagens de tilápia-do-nilo

O objetivo deste trabalho foi determinar a associação de polimorfismos no gene do hormônio crescimento GH1 às características corporais, em linhagens de tilápia-do-nilo (Oreochromis niloticus). Foram coletados fragmentos da nadadeira caudal de exemplares das linhagens, aos cinco meses de idade, para as análises de "polymerase chain reaction-restriction fragment lenght polymorphism" (PCR-RFLP). Foram realizadas as seguintes mensurações: comprimento total, comprimento padrão, altura, largura e comprimento da cabeça. Realizou-se a amplificação de um fragmento com 652 pb do gene GH1, com subsequente restrição com a enzima PstI. Para a análise de associação do marcador molecular com as características quantitativas, utilizou-se o procedimento GLM do SAS. O polimorfismo descrito para o íntron 1, do gene GH1 da tilápia-do-nilo, apresentou correlação significativa com o comprimento total, comprimento padrão, altura e largura corporal. Foi verificado que o genótipo PstI+/- está associado ao melhor crescimento, independentemente da linhagem. A associação verificada pode ter ocorrido em razão do efeito direto da regulação do próprio gene GH.

In vivo sensitivity reduction of Puccinia triticina races, causal agent of wheat leaf rust, to DMI and QoI fungicides

Experiments were carried out to determine in vivo the IC50 and the IC90 for demethylation-inhibitor fungicides (DMIs, triazoles) and quinone outside inhibitors (QoIs, strobilurins) to the five most frequent races of Puccinia triticina in 2007 growing season in Southern Brazil. The tests were done in a greenhouse with wheat seedlings. DMI fungicides were tested at the concentrations, in mg/L, 0.0; 0.02; 0.2; 2.0; 20.0; 100.0 and 200.0, and QoIs at the concentrations 0.0; 0.0001; 0.001; 0.01; 0.1; 1 and 10.0 mg of active ingredient/L water. Fungicides were preventively applied at 24 hours before the inoculation of seedlings with the fungal spores. The effect of treatments was assessed based on the number of uredia/cm². The lowest IC50 (inhibitory concentration) for DMI fungicides determined for MCG-MN, sensitive race, ranged from 0.33 to 0.91 mg/L, while the highest values for MDP-MR, MDT-MR, MDK-MR, MFH-HT races, varied from 9.63 to 85.64 mg/L (suspected insensitivity). QoI fungicide presented an IC50 varying from 0.0018 to 0.14 mg/L. The sensitivity reduction factor for DMIs varied from 8.8 to 238.8, and for QoIs from 0.3 to 1.5 mg/L. Sensitivity reduction was confirmed for the races MDP-MR, MDT-MR, MDK-MR, MFH-HT to DMIs, as well as their sensitivity to QoI fungicides.

Ciclooxigenase-2 nos carcinomas ductais de mama invasivos com componente ductal in situ e no epitélio adjacente

OBJETIVO: avaliar a presença da ciclooxigenase-2 (COX-2) nos carcinomas de mama ductal in situ (CDIS) e ductal invasivo (CDI), no estroma adjacente normal e no epitélio. A correlação entre os níveis de expressão com os graus nuclear e histológico, tamanho do tumor e idade da paciente foi também analisada. MÉTODOS: foram incluídos 47 espécimes cirúrgicos provenientes de mastectomias e quadrantectomias com CDI e CDIS concomitantes, estádios clínicos I e II. Foram utilizados anticorpos policlonais anti-COX-2 para determinar a expressão da enzima. As amostras foram categorizadas em escores de zero a três, de acordo com a intensidade e o número de células coradas. RESULTADOS: COX-2 foi positivamente expressa em CDI, CDIS e epitélio normal em 86,7, 84,4 e 73,3% dos casos, respectivamente. Quanto ao grau nuclear (GN), a expressão da COX-2 foi positiva em 80% dos casos de GN-I; 81,5 e 78,9% de GN-II; e 88,5 e 96,1% de GN-III no CDIS e CDI, respectivamente. A expressão da COX-2 ocorreu em 78,9% dos CDIS com comedonecrose e em 89,3% sem comedonecrose. Quanto ao grau histológico (GH) do CDI, a COX-2 foi positiva em 83,3% de GH-I; 89,9% de GH-II e 80% de GH-III. Em relação ao diâmetro tumoral, COX-2 esteve presente em 86,1% de CDI e 83,3% de CDIS em tumores com >2 cm de diâmetro e 11% em CDI; e CDIS em tumores ≤ 2 cm. A faixa etária ≥ 50 anos apresentou 90% de expressão para CDI e 86,7% para CDIS, e 92,5% de COX-2 para ambos CDI e CDIS em pacientes com idade <50 anos. CONCLUSÕES: nossos resultados demonstram alta correlação entre as expressões da COX-2 nos CDI, CDIS e epitélio normal, o que é consistente com a hipótese de que a superexpressão da COX-2 é um evento precoce na carcinogênese mamária. Não houve diferença quando da análise do grau histológico, presença de comedonecrose, grupo etário e tamanho do tumor.

An experimental investigation of the effects of nozzle ellipticity on the flow structure of co-flow jet diffusion flames

The flow structure of cold and ignited jets issuing into a co-flowing air stream was experimentally studied using a laser Doppler velocimeter. Methane was employed as the jet fluid discharging from circular and elliptic nozzles with aspect ratios varying from 1.29 to 1.60. The diameter of the circular nozzle was 4.6 mm and the elliptic nozzles had approximately the same exit area as that of the circular nozzle. These non-circular nozzles were employed in order to increase the stability of attached jet diffusion flames. The time-averaged velocity and r.m.s. value of the velocity fluctuation in the streamwise and transverse directions were measured over the range of co-flowing stream velocities corresponding to different modes of flame blowout that are identified as either lifted or attached flames. On the basis of these measurements, attempts were made to explain the existence of an apparent optimum aspect ratio for the blowout of attached flames observed at higher values of co-flowing stream velocities. The insensitivity of the blowout limits of lifted flames to nozzle geometry observed in our previous work at low co-flowing stream velocities was also explained. Measurements of the fuel concentration at the jet centerline indicated that the mixing process was enhanced with the 1.38 aspect ratio jet compared with the 1.60 aspect ratio jet. On the basis of the obtained experimental data, it was suggested that the higher blowout limits of attached flames for an elliptic jet of 1.38 aspect ratio was due to higher entrainment rates.

Initialism as a mechanism of weed interference: can a crop plant be blinded?

Initialism is a new word proposed to indicate the "shade-avoidance syndrome". Plants detect the presence of neighbor plants very early in the growing season through changes in light quality. They modify the allocation of photosynthesis products privileging shoot growth over the roots. One of the hypotheses of the authors is that, when weed management is timely scheduled, a "blind" crop could be more productive because it would avoid an imbalance on the shoot:root ratio (S:R). Two strategies were developed to test this hypothesis: a) to use the classical Yoda's Law to screen several crops for insensitivity to S:R imbalance; b) to evaluate several growth regulators to control the plant responses to crowding. Experimental results confirm that both strategies can yield insensitive plants. The possibilities of the use of this knowledge are discussed.

Acetolactate synthase activity in Euphorbia heterophylla resistant to ALS- and protox- inhibiting herbicides

The objective of this study was to determine the activity of the enzyme acetolactate synthase in biotypes of wild poinsettia (Euphorbia heterophylla) with multiple resistance to ALS- and Protox- inhibitors in the presence and absence of imazapyr, imazethapyr and nicosulfuron. We conducted in vitro assay of ALS enzyme extracted from plants of Vitorino, Bom Sucesso do Sul and Medianeira biotypes (with multiple resistance) and a susceptible population in the absence and presence of imazapyr, imazethapyr and nicosulfuron. In the absence of herbicides, biotypes with multiple resistance showed higher affinity for the substrate of the enzyme compared with the susceptible population. The herbicides imazapyr, imazethapyr and nicosulfuron had little effect on the enzyme activity of ALS-resistant biotypes and, conversely, high inhibitory effect on ALS of the susceptible population. Resistance factors were very high, greater than 438, 963 and 474 for Vitorino, Bom Sucesso do Sul and Medianeira biotypes, respectively. The resistance to ALS inhibitors is due to the insensitivity of ALS to herbicides of both imidazolinone and sulfonylurea groups, characterizing a cross-resistance.

Glyphosate influence on the physiological parameters of Conyza bonariensis biotypes

The objective of this study was to determine changes in gas exchange and inhibition of EPSPs, based on the accumulation of shikimic acid in horseweed biotypes resistant and sensitive to glyphosate. Two experiments were conducted in a factorial model. The first one evaluated horseweed biotypes (one resistant and one susceptible to glyphosate), and herbicide rates (0 and 1,080 g a.e. ha ¹) applied on the weed. In the second experiment, the horseweed biotypes (susceptible and resistant to glyphosate) were evaluated in five periods as following: 0, 3, 7, 10, and 14 days after herbicide application (DAH). The photosynthetic rate, transpiration, carboxylation efficiency, and water efficiency were determined using an infrared gas analyzer (IRGA), and shikimic acid concentration by HPLC. The application of glyphosate damaged the photosynthetic parameters of the susceptible biotype, causing complete inhibition of the photosynthetic rate, transpiration rate, carboxylation efficiency and water use efficiency, starting from the 7 DAH. On the other hand, total inhibition of the photosynthetic parameters was not observed for the resistant biotype. Shikimic acid accumulation occurred in both biotypes after glyphosate application but the susceptible biotype had the highest concentrations, indicating greater sensitivity of the enzyme EPSPs. The accumulation of shikimic acid in the resistant biotype indicates that the mechanism of resistance is not related to the total insensitivity of the enzyme EPSPs to glyphosate and/or that other resistance mechanisms may be involved.

Hormonal response during a fenfluramine-associated panic attack

Secretion curves for prolactin, cortisol, TSH, and GH from a 37-year old woman with dysthymia and panic disorder with agoraphobia were determined one day prior to (day I), and during a panic attack (day II) associated with an oral dose of 60 mg dl-fenfluramine, a drug known to increase anticipatory anxiety. The increased cortisol secretion observed is discussed in relation to the hormonal correlates of anxiety and the possible role of depression, dl-fenfluramine, and serotonergic receptor sensitivity

Clinical and molecuar characterization of Brazilian patients with growth hormone gene deletions

Genomic DNA from 23 patients with isolated growth hormone (GH) deficiency (12 males and 11 females: heights -4.9 ± 1.4 SDS) was screened for GH gene deletions by restriction endonuclease analysis of polymerase chain reaction amplification products. Three unrelated patients had typical features of severe GH deficiency and deletions (6.7 kb in two and 7.6 kb in one) of the GH gene. The two patients with 6.7-kb deletions developed growth-attenuating anti-GH antibodies whereas the patient with the 7.6-kb deletion continued to grow with GH replacement therapy. Our finding that 3/23 (~13%) Brazilian subjects had GH gene deletions agrees with previous studies of severe isolated GH deficiency subjects in other populations. Two of three subjects (67%) with deletions developed blocking antibodies despite administration of exogenous GH at low doses. Interestingly, only 1/10 of cases with affected relatives or parental consanguinity had GH-1 gene deletions

Feeding manipulation elicits different proliferative responses in the gastrointestinal tract of suckling and weanling rats

Food deprivation has been found to stimulate cell proliferation in the gastric mucosa of suckling rats, whereas the weanling period has been reported to be unresponsive in terms of proliferative activity. In the present study we analyze regional differences in the effect of milk or food deprivation on cell proliferation of the epithelia of the esophagus and of five segments of small intestine in suckling, weanling and newly weaned Wistar rats of both sexes. DNA synthesis was determined using tritiated thymidine to obtain labeling indices (LI); crypt depth and villus height were also determined. Milk deprivation decreased LI by 50% in the esophagus (from 15 to 8.35%) and small intestine (from 40 to 20%) of 14-day-old rats. In 18-day-old rats, milk and food deprivation decreased LI in the esophagus (from 13 to 5%) and in the distal segments of the small intestine (from 36-40 to 24-32%). In contrast, the LI of the epithelia of the esophagus (5%) and of all small intestine segments (around 30%) of 22-day-old rats were not modified by food deprivation. Crypt depth did not change after treatment (80 to 120 µm in 14- and 22-day-old rats, respectively). Villus height decreased in some small intestine segments of unfed 14- (from 400 to 300 µm) and 18-day-old rats (from 480 to 360 µm). The results show that, contrary to the stomach response, milk deprivation inhibited cell proliferation in the esophagus and small intestine of suckling rats, demonstrating the regional variability of each segment of the gastrointestinal tract in suckling rats. In newly weaned rats, food deprivation did not alter the proliferation of these epithelia, similarly to the stomach, indicating that weanling is a period marked by the insensitivity of gastrointestinal epithelia to dietary alterations

Mutations of androgen receptor gene in Brazilian patients with male pseudohermaphroditism

We describe the identification of point mutations in the androgen receptor gene in five Brazilian patients with female assignment and behavior. The eight exons of the gene were amplified by the polymerase chain reaction (PCR) and analyzed for single-strand conformation polymorphism (SSCP) to detect the mutations. Direct sequencing of the mutant PCR products demonstrated single transitions in three of these cases: G®A in case 1, within exon C, changing codon 615 from Arg to His; G®A in case 2, within exon E, changing codon 752 from Arg to Gln, and C®T in case 3, within exon B, but without amino acid change.

Morphometric and ultrastructural analysis of different pituitary cell populations in undernourished monkeys

Undernutrition elicited by a low-protein diet determines a marked reduction of hypophyseal activity and affects the function of the respective target organs. The objective of the present investigation was to study the ultrastructural and quantitative immunohistochemical changes of the different pituitary cell populations in undernourished monkeys that had been previously shown to have significant changes in craniofacial growth. Twenty Saimiri sciureus boliviensis monkeys of both sexes were used. The animals were born in captivity and were separated into two groups at one year of age, i.e., control and undernourished animals. The monkeys were fed ad libitum a 20% (control group) and a 10% (experimental group) protein diet for two years. Pituitaries were processed for light and electron microscopy. The former was immunolabeled with anti-GH, -PRL, -LH, -FSH, -ACTH, and -TSH sera. Volume density and cell density were measured using an image analyzer. Quantitative immunohistochemistry revealed a decrease in these parameters with regard to somatotrophs, lactotrophs, gonadotrophs and thyrotrophs from undernourished animals compared to control ones. In these populations, the ultrastructural study showed changes suggesting compensatory hyperfunction. On the contrary, no significant changes were found in the morphometric parameters or the ultrastructure of the corticotroph population. We conclude that in undernourished monkeys the somatotroph, lactotroph, gonadotroph, and thyrotroph cell populations showed quantitative immunohistochemical changes that can be correlated with ultrastructural findings.