Structural basis for the recognition of complex-type biantennary oligosaccharides by Pterocarpus angolensis lectin

The crystal structure of Pterocarpus angolensis lectin is determined in its ligand-free state, in complex with the fucosylated biantennary complex type decasaccharide NA2F, and in complex with a series of smaller oligosaccharide constituents of NA2F. These results together with thermodynamic binding data indicate that the complete oligosaccharide binding site of the lectin consists of five subsites allowing the specific recognition of the pentasaccharide GlcNAc beta(1-2)Man alpha(1-3)[GlcNAc beta(1-2)Man alpha(1-6)]Man. The mannose on the 1-6 arm occupies the monosaccharide binding site while the GlcNAc residue on this arm occupies a subsite that is almost identical to that of concanavalin A (con A). The core mannose and the GlcNAc beta(1-2)Man moiety on the 1-3 arm on the other hand occupy a series of subsites distinct from those of con A.     

Differential activation of p38MAPK isoforms by MKK6 and MKK3

All four members of the mammalian p38 mitogen-activated protein kinase (MAPK) family (p38α, p38β, p38γ and p38δ) are activated by dual phosphorylation in the TGY motif in the activation loop. This phosphorylation is mediated by three kinases, MKK3, MKK6 and MKK4, at least in vitro. The role of these MKK in the activation of p38α has been demonstrated in studies using fibroblasts that lack MKK3 and/or MKK6. Nonetheless, the physiological upstream activators of the other p38MAPK isoforms have not yet been reported using MKK knockout cells. In this study, we examined p38β, γ and δ activation by MKK3 and MKK6, in cells lacking MKK3, MKK6 or both. We show that MKK3 and MKK6 are both essential for the activation of p38γ and p38β induced by environmental stress, whereas MKK6 is the major p38γ activator in response to TNFα. In contrast, p38δ activation by ultraviolet radiation, hyperosmotic shock, anisomycin or by TNFα is mediated by MKK3. Moreover, in response to osmotic stress, MKK3 and MKK6 are crucial in regulating the phosphorylation of the p38γ substrate hDlg and its activity as scaffold protein. These data indicate that activation of distinct p38MAPK isoforms is regulated by the selective and synchronized action of two kinases, MKK3 and MKK6, in response to cell stress.     

Yeast phenylalanyl-tRNA synthetase. Affinity and photoaffinity labelling of the stereospecific binding sites.

The localization of the binding sites of the different ligands on the constitutive subunits of yeast phenylalanyl-tRNA synthetase was undertaken using a large variety of affinity and photoaffinity labelling techniques. The RNAPhe was cross-linked to the enzyme by non-specific ultraviolet irradiation at 248 nm, specific irradiation in the wye base absorption band (315 nm), irradiation at 335 nm, in the absorption band of 4-thiouridine (S4U) residues introduced in the tRNA molecule, or by Schiff's base formation between periodate-oxidized tRNAPhe (tRNAPheox) and the protein. ATP was specifically incorporated in its binding site upon photosensitized irradiation. The amino acid could be linked to the enzyme upon ultraviolet irradiation, either in the free state, engaged in the adenylate or bound to the tRNA. The tRNA, the ATP molecule and the amino acid linked to the tRNA were found to interact exclusively with the beta subunit (Mr 63000). The phenylalanine residue, either free or joined to the adenylate, could be cross-linked with equal efficiency to eigher type of subunit, suggesting that the amino acid binding site is located in a contact area between the two subunits. The Schiff's base formation between tRNAPheox and the enzyme shows the existence of a lysyl group close to the binding site for the 3'-terminal adenosine of tRNA. This result was confirmed by the study of the inhibition of yeast phenylalanyl-tRNA synthetase with pyridoxal phosphate and the 2',3'-dialdehyde derivative of ATP, oATP.     

Overweight,Obesity and Underweight Is Associated with Adverse Psychosocial and Physical Health Outcomes among 7-Year-Old Children: The ‘Be Active,Eat Right’ Study

Background

Limited studies have reported on associations between overweight, and physical and psychosocial health outcomes among younger children. This study evaluates associations between overweight, obesity and underweight in 5-year-old children, and parent-reported health outcomes at age 7 years.

Methods

Data were used from the ‘Be active, eat right’ study. Height and weight were measured at 5 and 7 years. Parents reported on child physical and psychosocial health outcomes (e.g. respiratory symptoms, general health, happiness, insecurity and adverse treatment). Regression models, adjusted for potential confounders, were fitted to predict health outcomes at age 7 years.

Results

The baseline study sample consisted of 2,372 children mean age 5.8 (SD 0.4) years; 6.2% overweight, 1.6% obese and 15.0% underweight. Based on parent-report, overweight, obese and underweight children had an odds ratio (OR) of 5.70 (95% CI: 4.10 to 7.92), 35.34 (95% CI: 19.16; 65.17) and 1.39 (95% CI: 1.05 to 1.84), respectively, for being treated adversely compared to normal weight children. Compared to children with a low stable body mass index (BMI), parents of children with a high stable BMI reported their child to have an OR of 3.87 (95% CI: 1.75 to 8.54) for visiting the general practitioner once or more, an OR of 15.94 (95% CI: 10.75 to 23.64) for being treated adversely, and an OR of 16.35 (95% CI: 11.08 to 24.36) for feeling insecure.

Conclusion

This study shows that overweight, obesity and underweight at 5 years of age is associated with more parent-reported adverse treatment of the child. Qualitative research examining underlying mechanisms is recommended. Healthcare providers should be aware of the possible adverse effects of childhood overweight and also relative underweight, and provide parents and children with appropriate counseling.     

ING2 regulates the onset of replicative senescence by induction of p300-dependent p53 acetylation

ING2 is a candidate tumor suppressor gene that can activate p53 by enhancing its acetylation. Here, we demonstrate that ING2 is also involved in p53-mediated replicative senescence. ING2 protein expression increased in late-passage human primary cells, and it colocalizes with serine 15-phosphorylated p53. ING2 and p53 also complexed with the histone acetyltransferase p300. ING2 enhanced the interaction between p53 and p300 and acted as a cofactor for p300-mediated p53 acetylation. The level of ING2 expression directly modulated the onset of replicative senescence. While overexpression of ING2 induced senescence in young fibroblasts in a p53-dependent manner, expression of ING2 small interfering RNA delayed the onset of senescence. Hence, ING2 can act as a cofactor of p300 for p53 acetylation and thereby plays a positive regulatory role during p53-mediated replicative senescence.     

Seasonal phenotypic plasticity: wild ladybirds are darker at cold temperatures

Seasons vary in the average environmental conditions a species experiences, meaning that optimum strategies for concealment or feeding may also vary. Populations of the ladybird Harmonia axyridis contain both melanic and non-melanic forms and changes in allele frequency in some populations suggest that melanism may be advantageous in winter, but costly in summer. This could favour the evolution of phenotypic plasticity in colour pattern, as individuals which changed colour throughout the year would be able to maximise their fitness. We have previously shown in the laboratory that melanisation in the “non-melanic” morph of H. axyridis, f. succinea, is predominantly controlled by temperature during development. We now report that wild populations of H. axyridis f. succinea also conform to this principle: lower field temperatures during development produce individuals with more and larger spots. Furthermore, we have found that the critical period of development where temperature affects the level of melanisation covers the pupal and late larval stages, and melanisation increases with the length of time spent at cold temperature. We conclude it is likely that the temperature experienced during this period is used to predict the temperature encountered as an adult. This may allow individuals to produce the level of melanisation necessary to maintain activity levels at the temperatures encountered when they emerge. The long sensitive period seen in H. axyridis may be in order to avoid mismatches between melanisation and seasonal environment.     

Effects of Light Gaps and Litter Removal on the Seedling Performance of Six African Timber Species1

Valuable timber tree species frequently show poor regeneration after selective logging in tropical forests. Small size of logging gaps, lack of soil disturbance, and limited seed availability have each been blamed for observed regeneration failures. We investigated seed germination and seedling performance using a split‐plot factorial design involving light availability and litter removal for six Central African timber tree species, hypothesizing that canopy gaps and litter removal would improve seedling establishment, and that less shade‐tolerant species would show stronger responses to both factors. Contrary to our expectations, significantly more germinants established on intact litter than on exposed mineral soil 3 mo after seeding. After 18 mo, seedling survival, height and diameter growth, leaf area, and rooting depth were all much higher in gap plots than in the understory for all species, with the exception of Gilbertiodendron dewevrei, a highly shade‐tolerant species whose survival was higher in the understory. Leaf production was negatively influenced by litter removal in the least shade‐tolerant species, Nauclea diderrichii, with weak or positive effects in other species. G. dewevrei, while displaying a low‐light threshold for growth, exhibited a surprisingly high growth response to increasing light comparable to more shade‐intolerant species, a response that may help explain its local competitive dominance in the region. Due to the rapid closure of small gaps, we suggest that shade‐intolerant species such as N. diderrichii, Khaya anthotheca, and Entandrophragma utile might benefit from more intensive silvicultural practices that create larger canopy gaps.