A posição do gen Y3 no cromossomo 2 do milho

This paper deals with the genetic relations among y3 - lg1 - gl2. The data obtained indicate the relative order in chromosome 2 as follows: y3 7 gl1 18 gl2.

Milho: a Interação Y1 Y3 Y7 na coloração amarela do endosperma

This paper deals with the genetic interaction of Yl Y3 Y7 in producing yellow endosperm in maize. The new data presented are in accordance with preliminary notes on the same subject. The recessive yl, y3 and y7produce respectively green plants, albescent plants and white seedlings.

Purification of ribonucleotide reductase subunits Y1, Y2, Y3, and Y4 from yeast: Y4 plays a key role in diiron cluster assembly

Ribonucleotide reductases (RNRs) catalyze the conversion of nucleotides to deoxynucleotides. Class I RNRs are composed of two types of subunits: RNR1 contains the active site for reduction and the binding sites for the nucleotide allosteric effectors. RNR2 contains the diiron-tyrosyl radical (Y⋅) cofactor essential for the reduction process. Studies in yeast have recently identified four RNR subunits: Y1 and Y3, Y2 and Y4. These proteins have been expressed in Saccharomyces cerevisiae and in Escherichia coli and purified to ≈90% homogeneity. The specific activity of Y1 isolated from yeast and E. coli is 0.03 μmol⋅min−1⋅mg−1 and of (His)6-Y2 [(His)6-Y2-K387N] from yeast is 0.037 μmol⋅min−1⋅mg−1 (0.125 μmol⋅min−1⋅mg−1). Y2, Y3, and Y4 isolated from E. coli have no measurable activity. Efforts to generate Y⋅ in Y2 or Y4 using Fe2+, O2, and reductant have been unsuccessful. However, preliminary studies show that incubation of Y4 and Fe2+ with inactive E. coli Y2 followed by addition of O2 generates Y2 with a specific activity of 0.069 μmol⋅min−1⋅mg−1 and a Y⋅. A similar experiment with (His)6-Y2-K387N, Y4, O2, and Fe2+ results in an increase in its specific activity to 0.30 μmol⋅min−1⋅mg−1. Studies with antibodies to Y4 and Y2 reveal that they can form a complex in vivo. Y4 appears to play an important role in diiron-Y⋅ assembly of Y2.

Gender differences in CF phenotype associated with low bone mineral density

Adolescents and adults with CF have lower bone mineral density (BMD) than normal, but its relationship with phenotype is not well understood. Point FEV1% predicted (FEV) and rate of change of FEV are biased estimates of disease severity, because progressively older subjects represent a selected survivor population, with females at greater risk of death than males. To investigate the relationship between BMD and phenotype we used an index (predicted age at death) derived from Bayesian estimates of slope and intercept of FEV, age at last measurement and survival status. Predictive equations for the index were derived from 97 subjects (78 survivors) from the RCH CF clinic, and applied to a group of 102 comparable subjects who had BMD measured, classified as having‘mild’ ()75th), ‘moderate’ (25– 75th), or ‘severe’ (-25th centile) phenotype. Total body (TB) and lumbar spine (LS) BMD z-scores (Z) were compared, adjustingfor gender effects, using 2-way ANOVA. Annual mean change in FEV segregated, as expected, according to phenotype, ‘severe’ (ns25), ‘moderate’ (ns51) and ‘mild’ (ns25) y3.01(y3.73 to y2.30)%, y0.85(y1.36 to y0.35)%, 2.70(1.92 to 3.46)%, respectively, with no gender difference. LS and TB BMDZ were different in each phenotype (P-s 0.002), LS BMDZ for ‘severe’, ‘moderate’ and ‘mild’ y1.63(CI: y2.07 to y 1.19), y0.86(CI: y1.17 to y0.55), y0.06(CI: y0.54 to 0.41). Males had lower LS BMDZ than females overall (y1.22 (CI: y1.54 to y0.91) vs. y0.48(CI: y 0.84 to y0.12) Ps0.002). In the ‘severe’ group, males had lower TB BMDZ and LS BMDZ (PF0.002). Low BMD is associated with ‘moderate’ and ‘severe’ phenotypes, with relative preservation in females in the ‘severe’ group. Female biology (reproductive fitness) might promote resistance to bone resorption at a critical level of BMD loss.

NPY regulates catecholamine secretion from human adrenal chromaffin cells.

The aim of the present work was to find out whether NPY synthesized in human adrenal chromaffin cells controls in an autocrine/paracrine fashion the release of catecholamines by these cells. Accordingly, the constitutive and regulated release of both NPY and catecholamines was measured simultaneously in cultured human chromaffin cells. In addition, by using both RT-PCR and a combination of specific agonists and antagonists, we characterized the expression of NPY receptors on these cells as well as their pharmacology. Our results were as follows. 1) Human chromaffin cells constitutively secrete NPY. 2) Nicotine elicits a rapid increase in the release of both catecholamines and NPY; this release of NPY is more sustained than that of catecholamines. 3) RT-PCR shows expression of Y1, Y2, Y4, and Y5 receptor mRNA by chromaffin cells; these receptors are functional, as various receptor specific agonists elicit an increase in intracellular calcium. 4) Peptide YY, in contrast to NPY, is not able to stimulate the release of catecholamines. This finding was corroborated by the observation that no receptor-specific antagonists were able to reduce constitutive catecholamine release, whereas an NPY-immunoneutralizing antibody markedly attenuated the secretion. Taken together, these data suggest that NPY originating from the adrenal medulla locally enhances the secretion of catecholamines, presumably by acting via the putative y3 receptor.

Cultivo in vitro de embriões zigóticos e aclimatação de plântulas de coqueiro-anão

O objetivo deste trabalho foi ajustar os protocolos de cultivo in vitro de embriões zigóticos e de aclimatação de plântulas de coqueiro-anão-verde do Brasil de Jiqui (Cocos nucifera L.). Os embriões zigóticos maduros, colocados assepticamente em meio de cultura líquido Y3 suplementado com 27,8 mg L-1 de Fe2SO4.7H2O e 60 g L-1 de sacarose, apresentaram maior germinação e formação de plântulas normais. As plântulas transferidas para meio indutor de enraizamento Y3, gelificado e suplementado com 1 mg L-1 de ANA, 0,5 mg L-1 de BAP e 2,5 g L-1 de carvão ativado, apresentaram incremento do desenvolvimento radicular e da parte aérea. Na fase de aclimatação, o substrato composto por areia lavada e pó de casca de coco seco, na proporção de 1:1, proporcionou maior sobrevivência das plântulas (58,33%), maior crescimento da parte aérea (39,08 cm) e maior número de folhas (6,33). Os protocolos estabelecidos para o cultivo in vitro de embriões zigóticos e a aclimatação de coqueiro-anão-verde de Jiqui podem ser utilizados no intercâmbio e conservação de germoplasma.

Manitol para a conservação ex situ de coqueiro por crescimento mínimo

O objetivo deste trabalho foi determinar a concentração de manitol para a germinação e crescimento mínimo in vitro do coqueiro (Cocos nucifera). Os seguintes acessos foram utilizados: Anão-vermelho-do brasil-de-gramame (BRDG), Anão-amarelo-da-malásia (MYD), Gigante-do-brasil-praia-do-forte (BRA), Gigante-da-polinésia (PYT) e Gigante-de-rennel (RIT). Os embriões foram colocados em meio de cultura Y3 a diferentes concentrações de manitol (0, 0,1, 0,2, 0,3 e 0,4 mol L-1). Verificou-se inibição do crescimento da parte aérea na presença de 0,1, 0,2 e 0,3 mol L-1, para MYD e BRDG, e de 0,1 e 0,2 mol L-1, para PYT, BRA e RIT. O uso do manitol é uma estratégia promissora para a conservação por crescimento mínimo.

Indução de calo a partir de eixo embrionário de coqueiro (Cocos nucifera L.)

Este estudo teve como objetivo avaliar a capacidade de formação de calos a partir de tecidos originários do eixo embrionário de embriões zigóticos de coqueiro (Cocos nucifera L.) em diferentes concentrações de 2,4-D. O experimento foi instalado em delineamento inteiramente casualizado, em esquema fatorial 4x5 (4 concentrações de 2,4-D x 5 segmentos do eixo embrionário). Os eixos embrionários foram excisados longitudinalmente dos embriões zigóticos e, em seguida, submetidos à assepsia com hipoclorito de sódio (0,2%) por dois minutos, lavados com água destilada estéril e imersos por dois minutos em solução de ácido cítrico estéril (100 mg.L-1). Os eixos embrionários foram então seccionados em cinco segmentos correspondentes às posições A, B, C, D e E, e transferidos para placas de Petri contendo meio de cultura Y3, suplementado com quatro concentrações de 2,4-D (10-4; 1,36x10-4; 3,62x10-4 e 4,52x10-4 M), sacarose (50 g.L-1), carvão ativado (2,5 g.L-1) e vitaminas de Morel e Wetmore, mantidos em ambiente escuro, em temperatura de 25 ± 2ºC. Após 15 dias de inoculação, os segmentos A e B apresentaram 97,5% de explantes com calos friáveis na concentração de 10-4 M de 2,4-D, e 92,5% e 80%, respectivamente, na concentração de 1,36x10-4 M. O segmento E, em ambas as concentrações, apresentou 60% de calogênese. Após 30 dias de inoculação, os segmentos A e B apresentaram 100% e 97,5% de calogênese na concentração de 10-4 M, e 90% e 80%, respectivamente, na concentração de 1,36x10-4 M. Em ambas as concentrações, o segmento E apresentou de 55 a 57,5% de formação de calos. As concentrações de 2,4-D que melhor induzem calogênese, são as de 10-4 e 1,36x10-4 M. Os segmentos A, B e E apresentaram maior competência para calogênese.

In vitro development and acclimatization of dendezeiro (Elaeis guineensis)

Fruits and almond from the dendezeiro, oil palmbelonging to the Elaeis genus,are widely used for the production of cookingoils or for the pharmaceutical and cosmetic industries.In the last decade, this oil palm also emerged as a promising source for commercialbiofuel production. This study evaluated the effect of different culture media, MS (MURASHIGUE AND SKOOG) and Y3 (EEUWENS)and carbohydrates duringin vitro germination of zygotic embryos, the effect of growth regulators GA3, NAA and BA Ponin vitro seedling development, and the survival rate of acclimatized seedlingsof Manicoré hybrid (Elaeis oleifera x E. guineensis). Zygotic embryos were inoculated on MS and modified Y3 media, supplemented with different sucrose concentrations (30, 45, and 60 gL-1) or sorbitol (36 gL-1), and the germination rate was evaluated after 30 days. Subsequently, seedlings were transferred to modified Y3 culture medium supplemented with differentGA3 concentrations (3.5 and 7 mgL-1) or without it, combined or not with 1 mgL-1 of NAA, 5 mgL-1 of BAP.The highest germinationpercentage of germinated embryos (92%) was observed in MS medium supplemented with 36 gL-1 sorbitol. Culture media supplemented with growth regulatorsGA3, NAA and BAP promoted greater shoot lengththan control media. Rooted seedlings showed high survival percentage (85%) during acclimatization.

Studies of tetrahedral haloboron cations of pyridines and aliphatic tertiary amines

The preparation of the haloboron cations D2BF2 + and DD'BF 2+, where D=R3N or a pyridine, has been systematically . 19 11 studied uS1ng F and B n.m.r. Both types of amines form numerous difluoroboron cations by heavy halogen displacement from D.BF 2X (X=CI,Br) adducts. Previously, D.BFX2 (X=CI,Br) adducts of aliphatic tertiary amines were unreactive towards cation formation. However, with the more-reactive pyridines, D.BFX 2 adducts formed new monofluoroboron cations D2BFX+ In non-fluorinated D.BX Y3 systems for n -n both pyridines and R3N, haloboron cations of type D2BX2 + and D2BXY+ can be similarly prepared. FAB-MS studies of ionic salts of our haloboron cations resulted in m/z peaks characteristic of D2 BX2 + and its f ragmentation products. These results s upport our n.m.r. solution s t u d ies. Pairwise interaction n . m.r . parameters for tetrahedral boron halide species were def i ned, then used to assist confirmation of our haloboron cations.

Credit Default Swaps (CDS) y Collateral Debt Obligation (CDO) derivados financieros responsables de la crisis sub-prime de 2008 en Estados Unidos y una guía para el desarrollo del mercado de derivados exóticos en Colombia

La crisis financiera hipotecaria de 2008 en la que se declaró en quiebra el banco de inversión Lehman Brothers, se desarrolló en un ambiente que contemplaba apalancamientos financieros excesivos y el uso de derivados financieros de crédito innovadores. Razón por la cual, a partir del estudio de caso de quiebra de este banco de inversión y el análisis de las causas y consecuencias del ambiente desregulatorio que surgió en Estados Unidos desde la década de los 30 hasta el 2000, se orienta la investigación a indagar sobre lo que sucede en términos regulatorios y empresariales en el mercado de valores colombiano y así lograr definir objetivos que permitan el crecimiento del mercado de derivados exóticos en Colombia bajo un marco de responsabilidad financiera y ética empresarial.

Assessment of the RE(OH)3 Ising magnetic materials as possible candidates for the study of transverse-field-induced quantum phase transitions

The LiHoxY1−xF4 Ising magnetic material subject to a magnetic field perpendicular to the Ho3+ Ising direction has shown over the past 20 years to be a host of very interesting thermodynamic and magnetic phenomena. Unfortunately, the availability of other magnetic materials other than LiHoxY1−xF4 that may be described by a transverse-field Ising model remains very much limited. It is in this context that we use here a mean-field theory to investigate the suitability of the Ho(OH)3, Dy(OH)3, and Tb(OH)3 insulating hexagonal dipolar Ising-type ferromagnets for the study of the quantum phase transition induced by a magnetic field, Bx, applied perpendicular to the Ising spin direction. Experimentally, the zero-field critical (Curie) temperatures are known to be Tc≈2.54, 3.48, and 3.72 K, for Ho(OH)3, Dy(OH)3, and Tb(OH)3, respectively. From our calculations we estimate the critical transverse field, Bxc, to destroy ferromagnetic order at zero temperature to be Bxc=4.35, 5.03, and 54.81 T for Ho(OH)3, Dy(OH)3, and Tb(OH)3, respectively. We find that Ho(OH)3, similarly to LiHoF4, can be quantitatively described by an effective S=1/2 transverse-field Ising model. This is not the case for Dy(OH)3 due to the strong admixing between the ground doublet and first excited doublet induced by the dipolar interactions. Furthermore, we find that the paramagnetic (PM) to ferromagnetic (FM) transition in Dy(OH)3 becomes first order for strong Bx and low temperatures. Hence, the PM to FM zero-temperature transition in Dy(OH)3 may be first order and not quantum critical. We investigate the effect of competing antiferromagnetic nearest-neighbor exchange and applied magnetic field, Bz, along the Ising spin direction ẑ on the first-order transition in Dy(OH)3. We conclude from these preliminary calculations that Ho(OH)3 and Dy(OH)3 and their Y3+ diamagnetically diluted variants, HoxY1−x(OH)3 and DyxY1−x(OH)3, are potentially interesting systems to study transverse-field-induced quantum fluctuations effects in hard axis (Ising-type) magnetic materials.