Human immunodeficiency virus transgenic rats exhibit pulmonary hypertension

Human immunodeficiency virus (HIV)-associated pulmonary arterial hypertension (PAH) is a serious noninfectious disease involving an aberrant increase in pressure in the blood vessels of the lung, which leads to right ventricular (RV) heart failure and can eventually result in death. A lack of viable animal models of HIV-PAH has limited the identification of signaling pathways involved in HIV-mediated onset and progression of PAH. To determine whether the HIV-1 transgenic (HIV Tg) rat displays pathophysiological end points associated with PAH, we evaluated peak RV systolic pressure (RVSP), RV hypertrophy, pulmonary vessel remodeling, and alterations in gene expression by real-time PCR and microarray. RVSP was measured by RV catheterization via the right jugular vein in 3- and 9-mo-old HIV Tg and age-matched Fischer 344 (control) male rats while under 2% isoflurane anesthesia. RVSP was elevated in the HIV Tg rats (34.2 ± 2.5 mmHg) compared with the F344 controls (21.2 ± 2.5 mmHg), with more significant elevations in the 9-mo-old HIV Tg rats (42.5 ± 3.7 mmHg). We observed significant increases in RV wall thickness in HIV Tg rats compared with controls, both histologically and by echocardiograph measurement. HIV Tg rats also show increased thickening of the pulmonary artery and remodeling of small pulmonary arteries, as well as altered expression of gene pathways associated with PAH. These data represent the first analysis of PAH in HIV Tg rats and suggest that this model will be useful for investigating pathways and identifying potential therapies for HIV-PAH.     

Synthesis, DNA binding, and oxidative cleavage studies of Fe(II) and Co(III) complexes containing bioactive ligands

The two complexes containing bioactive ligands of the type and [Fe(L)] (PF(6))(2) (1) (where L = [1-{[2-{[2-hydroxynaphthalen-1-yl)methylidine]amino}phenyl)imino] methyl}naphthalene-2-ol]) and [Co(L(1)L(2))] (PF(6))(3) (2) (where L(1)L(2) = mixed ligand of 2-seleno-4-methylquinoline and 1,10-phenanthroline in the ratio 1:2, respectively) were synthesized and structurally characterized. The DNA binding property of the complexes with calf thymus DNA has been investigated using absorption spectra, viscosity measurements, and thermal denaturation experiments. Intrinsic binding constant K(b) has been estimated at room temperature. The absorption spectral studies indicate that the complexes intercalate between the base pairs of the CT-DNA tightly with intrinsic DNA binding constant of 2.8 × 10(5) M(-1) for (1) and 4.8 × 10(5) M(-1) for (2) in 5 mM Tris-HCl/50 mM NaCl buffer at pH 7.2, respectively. The oxidative cleavage activity of (1) and (2) were studied by using gel electrophoresis and the results show that complexes have potent nuclease activity.     

Spatio-temporal analysis of development of basal roots of common bean (Phaseolus vulgaris L.)

Temporal development of roots is key to the understanding of root system architecture of plants which influences nutrient uptake, anchorage and plant competition. Using time lapse imaging we analyzed developmental patterns of length, growth angle, depth and curvature of Phaseolus basal roots from emergence till 48 h in two genotypes, {"type":"entrez-nucleotide","attrs":{"text":"B98311","term_id":"3000390","term_text":"B98311"}}B98311 and TLP19 with contrasting growth angles. In both genotypes all basal roots appeared almost simultaneously, but their growth rates varied which accounted for differences in root length. The growth angles of the basal roots fluctuated rapidly during initial development due to oscillatory root growth causing local bends. Beyond 24 h, as the root curvature stabilized, so did the growth angle. Therefore growth angle of basal roots is not a very reliable quantity for characterizing root architecture, especially during early seedling development. Comparatively, tip depth is a more robust measure of vertical distribution of the basal roots even during early seedling development.Key words: basal root, kinematics, root architecture, root growth, spatiotemporal analysis, root imagingVertical and horizontal placements of the roots in the soil influence plant performance through acquisition of below ground resources like water and nutrients, plant anchorage and intra- and inter-plant competition.^1–4 Therefore the architecture of the root system plays important roles in regulating plant growth and yield, especially under abiotic stresses.⁵ As a seedling grows to become a mature plant, the root architecture develops continuously in response to various cues e.g., genotypic, environmental, hormonal, etc. Therefore studies of root architecture of plants of different ages are important for understanding the influence of these cues in regulating plant growth.The root scaffold of a plant is comprised of different types of roots with different functions. A mature common bean (Phaseolus vulgaris L.) plant has root system consisting of primary, adventitious, lateral and basal roots. Among these, the basal roots are typically the earliest emerging secondary roots from the hypocotyl⁶ forming a major part of the mature root system. We have recently demonstrated important differences in architectural traits of the basal roots of common bean in the early seedling stage between two contrasting class of genotypes and how auxin-ethylene interplay regulates these traits.⁷ While this study of basal roots at a fixed time allows assessment and comparison of root development up to that point of time, investigation of the temporal events of emergence and growth of the basal roots is important and complementary to the understanding of their architectural traits. Therefore in the present study, we examined the detailed developmental patterns of basal roots through time lapse imaging in two genotypes.We chose two bean genotypes with contrasting basal root growth angles (BRGA) relative to the gravity—{"type":"entrez-nucleotide","attrs":{"text":"B98311","term_id":"3000390","term_text":"B98311"}}B98311 producing basal roots of smaller BRGA (41.7° ± 14°) and TLP19 having roots of larger BRGA (56.4° ± 18°).⁸ The germinated seedling with 2–3 cm radical was transferred to the blue germination paper (Anchor Paper Co., St. Paul, MN), which was suspended in nutrient solution⁷ inside a growth chamber (ACMAS Technocracy Limited, Delhi, India) maintained at 25 ± 1°C. Time lapse photography was carried out for 48 h at 30 min intervals using Nikon D200 digital camera fitted with a macro lens to obtain high resolution digital images of the roots. Imaging started from the visibility of the protrusions of emerging basal root along the root-shoot interface. A computer program was developed in Matlab^® 7.8 (Mathworks, Natick) to analyze the images semi-automatically. From every image the computer program identified the basal roots using contrast of color between the roots (mostly white) and the germination paper (blue). Root midlines were determined following the methodology of Miller et al.⁹ and smoothed using the method of overlapping polynomials. Length of the midline is root length. The angle between gravity and the line connecting the root tip to the base is BRGA.⁷ The vertical distance of the root tip from the base of the lowest emerging root along the gravity vector is tip depth. From the midline, root curvature was also determined using the equation κ=x′y″−y′x″(x′2+y′2)3/2,(1) where [x(x), y(s)] is coordinate of any point along the root midline, s is normalized distance along the midline, and the primes denote derivatives with respect to s. Here positive curvature signifies bending upward and vice versa.     

Structural basis for regulation of the Crk signaling protein by a proline switch

Proline switches, controlled by cis-trans isomerization, have emerged as a particularly effective regulatory mechanism in a wide range of biological processes. Here we report the structures of both the cis and trans conformers of a proline switch in the Crk signaling protein. Proline isomerization toggles Crk between two conformations: an autoinhibitory conformation, stabilized by the intramolecular association of two tandem SH3 domains in the cis form, and an uninhibited, activated conformation promoted by the trans form. In addition to acting as a structural switch, the heterogeneous proline recruits cyclophilin A, which accelerates the interconversion rate between the isomers, thereby regulating the kinetics of Crk activation. The data provide atomic insight into the mechanisms that underpin the functionality of this binary switch and elucidate its remarkable efficiency. The results also reveal new SH3 binding surfaces, highlighting the binding versatility and expanding the noncanonical ligand repertoire of this important signaling domain.     

Nuclear and chloroplast DNA reassessment of the origin of Indian potato varieties and its implications for the origin of the early European potato

The modern cultivated potato was first recorded in Europe in 1562, but its area(s) of exportation has long been in dispute. Two competing hypotheses have proposed an Andean area (somewhere from upland Venezuela to northern Argentina) or a lowland south central Chilean area. Potato landraces from these two areas can be distinguished, although sometimes with difficulty, by (1) cytoplasmic sterility factors, (2) morphological traits, (3) daylength adaptation, (4) microsatellite markers, and (5) co-evolved chloroplast (cp) and mitochondria (mt) DNA. The Chilean introduction hypothesis originally was proposed because of similarities among Chilean landraces and modern European cultivars with respect to traits 2 and 3. Alternatively, the Andean introduction hypothesis suggests that (1) traits 2 and 3 of European potato evolved rapidly, in parallel, from Andean landraces to a Chilean type through selection following import to Europe, and (2) the worldwide late blight epidemics beginning in 1845 in the United Kingdom displaced most existing European cultivars and the potato was subsequently improved by importations of Chilean landraces. We reassess these two competing hypotheses with nuclear microsatellite and cpDNA analyses of (1) 32 Indian cultivars, some of which are thought to preserve putatively remnant populations of Andean landraces, (2) 12 Andean landraces, and (3) five Chilean landraces. Our microsatellite results cluster all Indian cultivars, including putatively remnant Andean landrace populations, with the Chilean landraces, and none with the old Andigenum landraces. Some of these Indian landraces, however, lack the cpDNA typical of Chilean landraces and advanced cultivars, indicating they likely are hybrids of Andean landraces with Chilean clones or more advanced cultivars. These results lead us to reexamine the hypothesis that early introductions of potato to Europe were solely from the Andes.     

The crystal structure of calcium- and integrin-binding protein 1: insights into redox regulated functions

Calcium- and integrin-binding protein 1 (CIB1) is involved in the process of platelet aggregation by binding the cytoplasmic tail of the alpha(IIb) subunit of the platelet-specific integrin alpha(Iib)beta(3). Although poorly understood, it is widely believed that CIB1 acts as a global signaling regulator because it is expressed in many tissues that do not express integrin alpha(Iib)beta(3). We report the structure of human CIB1 to a resolution of 2.3 A, crystallized as a dimer. The dimer interface includes an extensive hydrophobic patch in a crystal form with 80% solvent content. Although the dimer form of CIB1 may not be physiologically relevant, this intersub-unit surface is likely to be linked to alpha(IIb) binding and to the binding of other signaling partner proteins. The C-terminal domain of CIB1 is structurally similar to other EF-hand proteins such as calmodulin and calcineurin B. Despite structural homology to the C-terminal domain, the N-terminal domain of CIB1 lacks calcium-binding sites. The structure of CIB1 revealed a complex with a molecule of glutathione in the reduced state bond to the N-terminal domain of one of the two subunits poised to interact with the free thiol of C35. Glutathione bound in this fashion suggests CIB1 may be redox regulated. Next to the bound GSH, the orientation of residues C35, H31, and S48 is suggestive of a cysteine-type protein phosphatase active site. The potential enzymatic activity of CIB1 is discussed and suggests a mechanism by which it regulates a wide variety of proteins in cells in addition to platelets.