Evidence of an association between poly(3-hydroxybutyrate) accumulation and phosphotransbutyrylase expression in Bacillus megaterium

Molecular analysis of a genomic region of Bacillus megaterium, a polyhydroxybutyrate (PHB)- producing microorganism, revealed the presence of a gene coding for the enzyme phosphotransbutyrylase (Ptb). Enzyme activity was measured throughout the different growth phases of B. megaterium and was found to correlate with PHB accumulation during the late-exponential growth phase. Ptb expression was repressed by glucose and activated by the branched amino acids isoleucine and valine. Overexpression of ActBm, a σ 54 regulator from B. megaterium whose gene is located upstream from ptb, caused an increase in Ptb activity and PHB accumulation in B. megaterium

High-speed FPGA 10's complement adders-subtractors

This paper first presents a study on the classical BCD adders from which a carry-chain type adder is redesigned to fit within the Xilinx FPGA's platforms. Some new concepts are presented to compute the P and G functions for carry-chain optimization purposes. Several alternative designs are presented. Then, attention is given to FPGA implementations of add/subtract algorithms for 10's complement BCD numbers. Carry-chain type circuits have been designed on 4-input LUTs (Virtex-4, Spartan-3) and 6-input LUTs (Virtex-5) Xilinx FPGA platforms. All designs are presented with the corresponding time performance and area consumption figures. Results have been compared to straight implementations of a decimal ripple-carry adder and an FPGA 2's complement binary adder-subtractor using the dedicated carry logic, both carried out on the same platform. Better time delays have been registered for decimal numbers within the same range of operands.This work is supported by the Universities FASTA, Mar del Plata, Argentina, UNCPBA Tandil, Argentina, UAM ,Madrid, Spain, and URV, Tarragona, Spain; it has been partially granted by the CICYT of Spain under contract TEC2007- 68074-C02-02/MIC

Adding Recognition Discriminability Index to the Delayed Recall Is Useful to Predict Conversion from Mild Cognitive Impairment to Alzheimer's Disease in the Alzheimer's Disease Neuroimaging Initiative

Background: Ongoing research is focusing on the identification of those individuals with mild cognitive impairment (MCI) who are most likely to convert to Alzheimer's disease (AD). We investigated whether recognition memory tasks in combination with delayed recall measure of episodic memory and CSF biomarkers can predict MCI to AD conversion at 24-month follow-up. Methods: A total of 397 amnestic-MCI subjects from Alzheimer's disease Neuroimaging Initiative were included. Logistic regression modeling was done to assess the predictive value of all RAVLT measures, risk factors such as age, sex, education, APOE genotype, and CSF biomarkers for progression to AD. Estimating adjusted odds ratios was used to determine which variables would produce an optimal predictive model, and whether adding tests of interaction between the RAVLT Delayed Recall and recognition measures (traditional score and d-prime) would improve prediction of the conversion from a-MCI to AD. Results: 112 (28.2%) subjects developed dementia and 285 (71.8%) subjects did not. Of the all included variables, CSF Aβ1-42 levels, RAVLT Delayed Recall, and the combination of RAVLT Delayed Recall and d-prime were predictive of progression to AD (χ2 = 38.23, df = 14, p < 0.001). Conclusions: The combination of RAVLT Delayed Recall and d-prime measures may be predictor of conversion from MCI to AD in the ADNI cohort, especially in combination with amyloid biomarkers. A predictive model to help identify individuals at-risk for dementia should include not only traditional episodic memory measures (delayed recall or recognition), but also additional variables (d-prime) that allow the homogenization of the assessment procedures in the diagnosis of MCI.Fil: Russo, María Julieta. Fundación para la Lucha Contra las Enfermedades Neurológicas de la Infancia. Instituto de Investigaciones Neurológicas "Raúl Carrea"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Campos, Jorge. Fundación para la Lucha Contra las Enfermedades Neurológicas de la Infancia. Instituto de Investigaciones Neurológicas "Raúl Carrea"; ArgentinaFil: Vázquez, Silvia. Fundación para la Lucha Contra las Enfermedades Neurológicas de la Infancia. Instituto de Investigaciones Neurológicas "Raúl Carrea"; ArgentinaFil: Sevlever, Gustavo. Fundación para la Lucha Contra las Enfermedades Neurológicas de la Infancia. Instituto de Investigaciones Neurológicas "Raúl Carrea"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Allegri, Ricardo Francisco. Fundación para la Lucha Contra las Enfermedades Neurológicas de la Infancia. Instituto de Investigaciones Neurológicas "Raúl Carrea"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

NGC 2571: An intermediate-age open cluster with a White Dwarf candidate

CCD UBVI imaging photometry was carried out in the field of the open cluster NGC 2571. From the analysis of our data we state the cluster is at a distance of 1380 ± 130 pc and its age is 504±10 ×106 yr. The cluster mass function has a slope larger than a typical Salpeter's law. There are two notorious features in NGC 2571: the cluster contains a high proportion of stars located below the reference line that are serious candidates to be metallic line stars (probably Am-Fm), and shows also a sharp gap along its main sequence that cannot be explained by a random process nor by a biased rejection of cluster members. A striking blue object was detected in the cluster field that could be a white dwarf candidate.Facultad de Ciencias Astronómicas y Geofísica

Erratum: "Revisiting the area of the open cluster Stock 16"

Este documento es una errata de "Revisiting the area of the open cluster Stock 16" (ver documento relacionado).Facultad de Ciencias Astronómicas y GeofísicasInstituto de Astrofísica de La Plat

Revisiting the area of the open cluster Stock 16

Deep CCD UBV(RI)C photometry has been carried out in the area of the open cluster Stock 16. The different photometric diagrams indicate the presence of three superimposed stellar groups, all composed of early type stars. The first of them, the cluster Stock 16, suffers from slightly variable reddening with a mean color excess 〈EB-V〉 = 0.51. The second group, reddened by 〈EB-V〉 = 0.84, includes the Wolf-Rayet star WR50 (a WC7+OB), and the third one, with a mean 〈E B-V〉 = 1.18, also includes another Wolf-Rayet star, WR 51 (a WN4+OB?). Our results confirm the distance and reddening already stated for Stock 16 but include new members. Concerning the other two highly reddened groups, we show that the first one - located at a distance of 3600 pc - is probably related to an anonymous OB association behind Cen OB1 also at 3600 pc already mentioned in the literature; the other seems to be a distant OB association - at more than 9000 pc - which may belong to the Scutum-Crux spiral arm. In these two groups we find evidence that the absorption law, A V/EB-V = R amounts to 4.0 approximately. The ages of the different star populations in the zone range from 5 × 106 yr to 6.4 × 106 yr for Stock 16, 8 × 106 for the second most reddened group and 5 × 106 for the probable association in Scutum-Crux. A determination of the IMF slope of Stock 16 was also carried out for stars in the mass range 1.8 < M < 14 M ⊙, giving a normal value x = 1.3.Este documento tiene una corrección (ver documento relacionado).Facultad de Ciencias Astronómicas y GeofísicasInstituto de Astrofísica de La Plat

APOBEC3G mRNA expression in exposed seronegative and early stage HIV infected individuals decreases with removal of exposure and with disease progression

<p>Abstract</p> <p>Background</p> <p>APOBEC3G is an antiretroviral factor that acts by inducing G to A mutations. In this study, we examined the expression of APOBEC3G in uninfected HIV-1 exposed individuals at the time of their partner's diagnosis and one year later. We then compared this expression with that of infected individuals at different disease stages. APOBEC3G mRNA was measured in PBMCs from three groups: healthy controls with no known risk factor to HIV infection (n = 26), exposed uninfected individuals who had unprotected sex with their HIV+ partners for at least 3 months (n = 37), and HIV infected patients at various disease stages (n = 45), including 8 patients with low HIV viral loads < 10,000 copies/mL (LVL) for at least 3 years. Additionally, we obtained sequences from the env, gag, pol, nef, vif and the LTR of the patients' virus.</p> <p>Results</p> <p>Exposed uninfected individuals expressed higher APOBEC3G than healthy controls (3.86 vs. 1.69 relative expression units), and their expression significantly decreased after a year from the HIV diagnosis and subsequent treatment of their partners. Infected individuals showed a positive correlation (Rho = 0.57, p = 0.00006) of APOBEC3G expression with CD4+ T cell count, and a negative correlation with HIV viremia (Rho = -0.54, p = 0.00004). The percentage of G to A mutations had a positive correlation (Rho = 0.43, p = 0.0226) with APOBEC3G expression, and it was higher in LVL individuals than in the other patients (IQR 8.27 to 9.64 vs. 7.06 to 8.1, p = 0.0084). Out of 8 LVLs, 3 had hypermutations, and 4 had premature stop codons only in viral <it>vif</it>.</p> <p>Conclusion</p> <p>The results suggest that exposure to HIV may trigger APOBEC3G expression in PBMCs, in the absence of infection. Additionally, cessation of exposure or advanced disease is associated with decreased APOBEC3G expression.</p

Photometry of a Galactic field at l = 232, b = -6. The old open cluster Auner 1, the Norma-Cygnus spiral arm and the signature of the warped Galactic Thick Disk

We perform a detailed photometric study of the stellar populations in a Galactic Field at l = 232, b = -6 in the Canis Major (CMa) constellation. We present the first U,B,V,I photometry of the old open cluster Auner1 and determine it to be 3.25 Gyr old and to lie at 8.9 kpc from the Sun. In the background of the cluster, at more than 9 kpc, we detect a young population most probably associated to the Norma Cygnus spiral arm. Furthermore, we detect the signature of an older population and identify its Turn Off and Red Giant Branch. This population is found to have a mean age of 7 Gyrs and a mean metallicity of Z = 0.006 . We reconstruct the geometry of the stellar distribution and argue that this older population - often associated to the Canis Major {\it galaxy}- belongs in fact to the warped old thin/thick disk component along this line of sight.Comment: 19 pages, 7 eps figures (some degraded), accepted for publication in the Astronomical Journa

Heterospecific amplexus between Triprion petasatus (Anura: Hylidae) and Incilius valliceps (Anura: Bufonidae) from Yucatán, Mexico

The heterospecific amplex between Triprion petasatus and Incilius valliceps is documented for the first time in the locality of Piste, Yucatan Mexico. This behavior has been documented previously in other amphibians, many of them also explosive reproducers that take advantage of temporary bodies of water, in places with a marked dry season. Se documenta por primera vez el amplexo heteroespecífico entre Triprion petasatus e Incilius valliceps en la localidad de Pisté, Yucatán México. Este comportamiento ha sido documentado con anterioridad en otros anfibios, muchos de ellos también reproductores explosivos que aprovechan los cuerpos de agua temporales, en sitios con una marcada estación de secas