The bZIP mutant CEBPB (V285A) has sequence specific DNA binding propensities similar to CREB1

The bZIP homodimers CEBPB and CREB1 bind DNA containing methylated cytosines differently. CREB1 binds stronger to the C/EBP half-site GCAA when the cytosine is methylated. For CEBPB, methylation of the same cytosine does not affect DNA binding. The X-ray structure of CREB1 binding the half site GTCA identifies an alanine in the DNA binding region interacting with the methyl group of T, structurally analogous to the methyl group of methylated C. This alanine is replaced with a valine in CEBPB. To explore the contribution of this amino acid to binding with methylated cytosine of the GCAA half-site, we made the reciprocal mutants CEBPB(V285A) and CREB1(A297V) and used protein binding microarrays (PBM) to examine binding to four types of double-stranded DNA (dsDNA): 1) DNA with cytosine in both strands (DNA(C|C)), 2) DNA with 5-methylcytosine (M) in one strand and cytosine in the second strand (DNA(M|C)), 3) DNA with 5-hydroxymethylcytosine (H) in one strand and cytosine in the second strand (DNA(H|C)), and 4) DNA with both cytosines in all CG dinucleotides containing 5-methylcytosine (DNA(5mCG)). When binding to DNA(C|C), CEBPB (V285A) preferentially binds the CRE consensus motif (TGACGTCA), similar to CREB1. The reciprocal mutant, CREB1(A297V) binds DNA with some similarity to CEBPB, with strongest binding to the methylated PAR site 8-mer TTACGTAA. These data demonstrate that V285 residue inhibits CEBPB binding to methylated cytosine of the GCAA half-site.     

Leptin, adiponectin and pulmonary diseases

Adipose tissue produces leptin and adiponectin - energy-regulating adipokines that may also play a role in inflammatory pulmonary conditions, as suggested by some murine studies. Leptin and adiponectin and their respective receptors are expressed in the human lung. The association between systemic or airway leptin and asthma in humans is currently controversial, particularly among adults. The majority of the evidence among children however suggests that systemic leptin may be associated with greater asthma prevalence and severity, particularly among prepubertal boys and peripubertal/postpubertal girls. Systemic and airway leptin concentrations may also be disproportionately higher in chronic obstructive pulmonary disease (COPD) patients, particularly among women, and reflect greater airway inflammation and disease severity. Quite like leptin, the association between systemic and airway adiponectin and asthma in humans is also controversial. Some but not all studies, demonstrate that serum adiponectin concentrations are protective against asthma among premenopausal women and peripubertal girls. On the other hand, serum adiponectin concentrations are inversely associated with asthma severity among boys but positively associated among men. Further, systemic and airway adiponectin concentrations are higher in COPD patients than controls, as demonstrated by case-control studies of men. Systemic adiponectin is also positively associated with lung function in healthy adults but inversely associated with lung function in subjects with COPD. It is therefore possible that pro-inflammatory effects of adiponectin dominate under certain physiologic conditions and anti-inflammatory effects under others. The adipokine-lung disease literature has critical gaps that include a lack of adequately powered longitudinal or weight-intervention studies; inadequate adjustment for confounding effect of obesity; and unclear understanding of potential sex interactions. It is also uncertain whether adipokine derangements precede pulmonary disease or are a consequence of it. Future research will determine whether modulation of adipokines, independent of BMI, may allow novel ways to prevent or treat inflammatory pulmonary conditions.     

Antisense expression of chaperonin 60β in transgenic tobacco plants leads to abnormal phenotypes and altered distribution of photoassimilates

Chaperonins are a class of molecular chaperone, present in bacteria, mitochondria and chloroplasts, that are involved in protein folding and assembly in many organisms. Plastid α and β chaperonins have been suggested to be involved specifically in the assembly of Ribulose bisphosphate carboxylase/oxygenase. However, to date there is no direct evidence to confirm the in vivo role of plastid chaperonin 60 polypeptides as molecular chaperones. This paper reports on the production, by means of antisense technology, of transgenic tobacco plants with reduced levels of chaperonin 60β (Cpn60β). Antisense cpn 60β plants showed drastic phenotypic alterations including slow growth, delayed flowering, stunting and leaf chlorosis. The most extreme effect appeared to be lethality suggesting that cpn 60β functions are essential for viability. Cpn60β antisense plants accumulated Rubisco to specific activities equal to or higher than that of controls and had high plastid starch contents. These observations are discussed with respect to the suggestion that chaperonin is required for the assembly of active Rubisco in vivo . In addition, metabolic alterations in the antisense transgenic plants such as reduced soluble carbohydrate content as well as higher levels of starch in chloroplasts, suggest that Cpn60β may be required for import, assembly or membrane insertion of several chloroplast membrane proteins. These results are in agreements with the proposed role of Cpn60β as a molecular chaperone.     

Expression of one of the members of the Arabidopsis chaperonin 60β gene family is developmentally regulated and wound-repressible

To study the pattern of gene regulation of the plastid chaperonin 60 gene family a chimaeric gene was constructed fusing the 5-flanking region of the chaperonin 60 B3 gene to the -glucuronidase reporter gene. Histochemical and fluorometric analysis of the GUS activity present in transgenic plants harbouring this gene construct showed that the B3 promoter is expressed in leaves, stem, petioles and several flower tissues. The pattern of cell type-specific expression in stems and flowers was found to be developmentally regulated. Expression of the B3 promoter was found not to be heat-inducible, but highly repressed by wounding. The rapid decay in GUS activity upon wounding indicates that, at least under some physiological conditions, the gene product of this reporter gene is not as stable as has been previously thought.     

Changes in some blood constituents of Barki ewes during pregnancy and lactation under semi arid conditions

A study based on 12 pregnant and six dry Barki ewes was carried out to examine the changes in blood constituents during pregnancy and lactation periods. The blood parameters were blood hemoglobin, packed cell volume percent (PCV%), mean corpuscular hemoglobin concentration (MCHC), glucose, aspartate aminotransaminase (AST or GOT), alanine aminotransaminase (ALT or GPT), total plasma protein, albumin, globulin, albumin to globulin ratio (A/G), urea and creatinine. During pregnancy all these parameters started to increase significantly, but in different stages, reaching maximum values at parturition. In contrast, dry ewes showed almost stable values during the experimental period. From 10th week to parturition, PCV% and MCHC increased (P<0.01) in pregnant ewes, which resulted in increased (P<0.01) blood hemoglobin. Blood glucose increased from the 4th week of pregnancy to reach its maximum at parturition (60.15–90.08 mg/dl). The two transaminases increased significantly from the 2nd week (52.23–65.02 IU for AST and 8.02–15.12 IU for ALT). Plasma protein with its two components, albumin and globulin, increased significantly at the 6th week, but dropped throughout the 16–18th week of pregnancy. Urea and creatinine began to increase significantly after 10–12 weeks of pregnancy (from 54.73 to 72.11 mg/dl for urea and from 0.882 to 2.475 mg/dl for creatinine). During the first month of lactation, PCV decreased sharply in lactating ewes and was significantly lower than in dry ewes at the 3rd week of lactation (24.25 versus 27.17%), which resulted in a drop in blood hemoglobin at the 4th week (68.42 versus 74.00 g/l). However, lactating ewes maintained significantly higher values of MCHC (30.01–31.19% for lactating versus 29.87–27.48% for dry). In lactating ewes, levels of glucose, ALT, urea and creatinine returned to levels comparable to those in dry ewes. The same occurred with total plasma proteins, mainly due to a sharp decrease in globulin, while albumin remained higher than in dry ewes with a slow decline, which resulted in higher values of A/G ratio during lactation. Aspartate aminotransferase remained higher than in dry ewes.     

Placental compliance during fetal extracorporeal circulation.

The fetus requires large amounts of volume when weaning from cardiac bypass. This suggests that placental vasculature can act as a large capacitor in the fetal circulation. To assess placental compliance of fetal lambs, seven isolated in situ lamb placentas were placed on extracorporeal circulation. Umbilical artery blood flow was varied from 0 to 350 ml. min(-1). kg fetal wt(-1). Because the extracorporeal circuit is a closed system, volume changes in the placenta induced by umbilical artery pressure changes were measured from reciprocal volume changes in the reservoir. There was a wide range of change in absolute volume of blood within the fetal placental compartment (216.4 +/- 29.3 ml). Placental compliance was linear over the entire range of pressure changes exerted on the placental vasculature (r(2) = 0.83, P = 0.0001). This indicates that the placenta is a unique and sensitive capacitor in the fetal circulation. This information is important clinically because it establishes that aggressive resuscitation of the fetus using volume may be necessary when weaning the fetus from cardiac bypass.     

NOTE. NEW EUENDOLITHIC CYANOBACTERIA FROM THE BAHAMA BANK AND THE ARABIAN GULF: HYELLA RACEMUS SP. NOV.1

A new species of endolithic cyanobacteria, Hyella racemus sp. nov. (order Pleurocapsales), penetrates ooid grains in actively shoaling sands in shallow (0.5–5 m) waters of the Bahama carbonate platform and the Arabian Gulf. Hyella racemus is characterized by prolific branching, resulting in dense grape-like cell clusters that penetrate the carbonate substrate. The clusters radiate inward and form deep, isodiametric pits. Resin casts of these pits are framboid (raspberry-like) in shape. The borehole morphology conforms with the shape of the endolith body and can be identified in resin-cast preparations. Cell division is by cleavage with regular alternation of division planes. The sheath is tight, layered, and colorless or yellow-brown when under strong illumination. The new species is one of the most common endoliths in ooids of the Bahamas and the Arabian Gulf It differs from other members of this endolithic genus by its branching pattern and less prominent apical cells.     

Extracorporeal circulation in the isolated in situ lamb placenta: hemodynamic characteristics.

Decreased placental perfusion and respiratory gas exchange have been observed after experimental fetal cardiopulmonary bypass (CPB). To better characterize placental hemodynamics during CPB, seven isolated in situ lamb placentas were placed on a CPB circuit by use of umbilical arterial and venous cannulation. Measures were taken to simulate normal placental hemodynamics. Perfusion flow rates were varied from 15 to 300 ml.min-1.kg fetal wt-1 during normothermia and hypothermia. Placental vascular resistance (PVR) remained constant when perfusion pressure and flow were varied above 40 mmHg and 150 ml.min-1.kg-1, respectively. Below these values, PVR varied inversely. This increase in PVR was more marked when CPB was performed with hypothermia than with normothermia. The clinical implication is that decreased placental flow and pressure on CPB may lead to a vicious cycle, resulting in further impairment of placental perfusion and respiratory gas exchange. Hypothermia promotes this impairment.