Wiring diagrams of MAPK regulation by MEKK1, 2, and 3.

Mitogen-activated protein kinase (MAPK) pathways are activated by a plethora of stimuli. The literature is filled with papers describing the activation of different MAPKs by almost any stimulus or insult imaginable to cells. In this review, we use signal transduction wiring diagrams to illustrate putative upstream regulators for the MAPK kinase kinases, MEKK1, 2, and 3. Targeted gene disruption of MEKK1, 2, or 3 defined phenotypes for each MEKK associated with loss of specific MAPK regulation. Genetic analysis of MEKK function clearly defines specific components of the wiring diagram that require MEKK1, 2, or 3 for physiological responses. We propose that signal transduction network wiring diagrams are valuable tools for hypothesis building and filtering physiologically relevant phenotypic responses from less connected protein relations in the regulation of MAPK pathways.     

Nutrient dynamics within amazonian forests

Summary Relationships between fine root growth, rates of litter decomposition and nutrient release were analysed in a mixed forest on Tierra Firme, a Tall Amazon Caatinga and a Low Bana on podsolized sands near San Carlos de Rio Negro. Fine root growth in the upper soil layers (root mat+10 cm upper soil) was considerably higher in the Tierra Firme forest (1117 g m^-2 yr^-1) than in tall Cattinga (120) and Bana (235). Fine root growth on top of the root mat was stimulated significantly by added N in Tall Caatinga and Low Bana forests, by P in Tierra Firme and Bana forests, and by Ca only in the Tierra Firme forest. Rate of fine root growth in Tierra Firme forest on fresh litter is strongly correlated with the Mg and Ca content of litter. Rate of litter decomposition was inversely related to % lignin and the lignin/N ratio of litter. Litter contact with the dense root mat of the Tierra Firme increased rates of disappearance for biomass, Ca and Mg as compared with litter permanently separated or lifted weekly from the root mat to avoid root attachment. Nitrogen concentration of decomposing litter increased in all forests, net N released being observed only in Caryocar glabrum and Aspidosperma megalocarpum of the Tierra Firme forest after one year of exposure. Results emphasize the differences in limiting nutrients in amazonian forest ecosystems on contrasting soil types: Tierra Firme forests are particularly limited by Ca and Mg, while Caatinga and Bana forests are limited mainly by N availability.     

Nutrients and mass in litter and top soil of ten tropical tree plantations

The importance of litter to nutrient and organic matter storage and the possible influence of species selection on soil fertility in ten stands each consisting of a separate tree species were examined in this study. The plantations had been grown under similar conditions in an arboretum in the Luquillo Experimental Forest, Puerto Rico. The species involved were: Anthocephalus chinensis, Eucalyptus × patentinervis, E. saligna, Hernandia sonora, Hibiscus elatus, Khaya nyasica, Pinus caribaea var. hondurensis, P. elliottii var. densa, Swietenia macrophylla, and Terminalia ivorensis. After 26 yr, litter mass ranged from 5 mg ha^-1 in the H. sonora stand to 27.2 Mg ha^-1 in the P. caribaea stand. Nutrients in the litter (N, P, K, Ca, and Mg) also varied widely, but stands were ranked in different order when ranked by nutrients in the litter than then ranked according to accumulation of mass. Only E. saligna and A. chinensis stands were ranked similarly in accumulation of both nutrients and mass, and the stand of H. elatus was ranked higher with respect to nutrient accumulation than to accumulation of mass. The nutrient concentration in standing leaf litter generally increased in the order of recently fallen <old intact< fragmented. Nutrient concentration of standing leaf litter appears to increase with age and depth in the litter layer. The amount of nutrients stored in the litter compartment of these plantations was in the same order of magnitude as the quantity of available nutrients in the top 10-cm of mineral soil. Total litter mass was negatively correlated with the mass-weighted concentration of N, K, and Mg. The same relationship was found for Ca in the leaf litter and N in the fine wood litter compartments. In some stands (notably P. caribaea, P. elliottii, and E. saligna), leaf litter derived from species other than the species planted in that particular stand had higher nutrient concentration than leaf litter from the planted species. Soils of the 10 stands were classified in the same soil series and had similar texture (clay soils). However, significantly different chemical characteristics were found. Results obtained by analysis of covariance and by limiting comparisons to adjacent stands with similar soil texture, indicate that different species have had different influences on the concentration of available nutrients in soil.     

Prediction of near-term climate change impacts on UK wheat quality and the potential for adaptation through plant breeding

Wheat is a major crop worldwide, mainly cultivated for human consumption and animal feed. Grain quality is paramount in determining its value and downstream use. While we know that climate change threatens global crop yields, a better understanding of impacts on wheat end-use quality is also critical. Combining quantitative genetics with climate model outputs, we investigated UK-wide trends in genotypic adaptation for wheat quality traits. In our approach, we augmented genomic prediction models with environmental characterisation of field trials to predict trait values and climate effects in historical field trial data between 2001 and 2020. Addition of environmental covariates, such as temperature and rainfall, successfully enabled prediction of genotype by environment interactions (G × E), and increased prediction accuracy of most traits for new genotypes in new year cross validation. We then extended predictions from these models to much larger numbers of simulated environments using climate scenarios projected under Representative Concentration Pathways 8.5 for 2050–2069. We found geographically varying climate change impacts on wheat quality due to contrasting associations between specific weather covariables and quality traits across the UK. Notably, negative impacts on quality traits were predicted in the East of the UK due to increased summer temperatures while the climate in the North and South-west may become more favourable with increased summer temperatures. Furthermore, by projecting 167,040 simulated future genotype–environment combinations, we found only limited potential for breeding to exploit predictable G × E to mitigate year-to-year environmental variability for most traits except Hagberg falling number. This suggests low adaptability of current UK wheat germplasm across future UK climates. More generally, approaches demonstrated here will be critical to enable adaptation of global crops to near-term climate change.     

mtDNA diversity in rhesus monkeys reveals overestimates of divergence time and paraphyly with neighboring species

Reconstructions of the human-African great ape phylogeny by using mitochondrial DNA (mtDNA) have been subject to considerable debate. One confounding factor may be the lack of data on intraspecific variation. To test this hypothesis, we examined the effect of intraspecific mtDNA diversity on the phylogenetic reconstruction of another Plio- Pleistocene radiation of higher primates, the fascicularis group of macaque (Macaca) monkey species. Fifteen endonucleases were used to identify 10 haplotypes of 40-47 restriction sites in M. mulatta, which were compared with similar data for the other members of this species group. Interpopulational, intraspecific mtDNA diversity was large (0.5%- 4.5%), and estimates of divergence time and branching order incorporating this variation were substantially different from those based on single representatives of each species. We conclude that intraspecific mtDNA diversity is substantial in at least some primate species. Consequently, without prior information on the extent of genetic diversity within a particular species, intraspecific variation must be assessed and accounted for when reconstructing primate phylogenies. Further, we question the reliability of hominoid mtDNA phylogenies, based as they are on one or a few representatives of each species, in an already depauperate superfamily of primates.      

Wiedemann-Beckwith syndrome: clinical, cytogenetical and radiological observations in 39 new cases.

Thirty-nine patients (82% under 1 year of age) with Wiedemann-Beckwith syndrome (WBS) were prospectively studied. To evaluate the somatometric data the normal range was set out at mean +/- 2 SD. The relevant physical findings were a characteristic face, non increased mean height and weight, normal head circumference, defective abdominal wall, a predominance of the upper segment, and tibial bowing. Mental retardation was documented in 5 cases but in only 1 it was related to hypoglycemia. The 32 cases karyotyped were normal. Since neonatal hypoglycemia is frequent (34.3% in our series) and potentially deleterious for the CNS we propose to monitor the glycemia every 6 h during the first 3 days in WBS newborns in order to correct glycemia below of 2.6 mmol/l (46.8 mg/dl) according to recent studies. The comparison with previous large series enabled us to precise the frequency, onset and evolution of the main stigmata.     

Sulfoconjugation of steroids and the vascular pathway of communication in dogfish testis.

The zonal testis of the dogfish (Squalus acanthias) has proven advantageous to study biochemical changes in relation to stage of spermatogenesis, including information on steroidogenic enzymes and steroid receptors. To investigate whether sulfotransferase is part of a mechanism regulating the availability of biologically active hormone in close proximity to receptors, we measured in vitro conversion of [3H]estrone (E1) to sulfoconjugated metabolites in cytosolic subfractions of testes grossly dissected according to germ cell composition (premeiotic-PrM, meiotic-M, and postmeiotic-PoM stages). Assays were carried out in the presence of adenosine 3'-phosphate 5'-phosphosulfate (PAPS) at 22 degrees C and optimized for time (60 min) and protein (500 micrograms/ml). Michaelis-Menten kinetics and saturation analysis gave the following reaction constants for [3H]E1: Km = 0.33 microM, Vmax = 2.5 pmol/min/mg; and for PAPS: Km = 33 microM, Vmax = 1.1 pmol/min/mg; competition studies carried out in the absence or presence of 1- or 5-fold excess radioinert steroids indicated that estrogen (E2 > E1) as well as androgens (T = DHEA > 5 alpha dihydrotestosterone, DHT) were effective inhibitors. Sulfotransferase activity was found to be stage-related, being highest in PoM regions (2.31 +/- 0.24 pmol/min/mg protein) when compared to M and PrM regions (1.22 +/- 0.22 and 1.28 +/- 0.21 pmol/min/mg protein, respectively). Sulfoconjugation and the intratesticular distribution of steroid sulfates were also measured in vivo by perfusion of the intact testis with [3H]androgen or -estrogen. The pathway of blood flow via the genital artery was epigonal organ-->PoM-->M-->PrM (mature-->immature). Perfused [3H]E2, T, and DHT were all extensively metabolized in a one-pass, 1 hr perfusion, less than 10% of perfused [3H] steroid being recovered from testicular tissues as unchanged steroid. In general, recovery of polar metabolites was greater than non-polar metabolites from all three substrates. Sequential hydrolysis with glucuronidase and glusulase indicated that sulfoconjugation is a minor component (< 20%) of several "inactivating" pathways, which include glucuronide conjugation, 17-ketosteroid synthesis, and pathways leading to unidentified polar metabolites. No consistent stage-related distribution patterns were observed for any of the metabolite subfractions; however, total recovered radioactive steroid (polar plus non-polar) formed a decreasing concentration gradient from point of entry of perfusate (PoM region) to point of exit (PrM region). These data support the conclusion that access to receptors by steroid ligands may be controlled by a balance between activating and inactivating pathways.(ABSTRACT TRUNCATED AT 400 WORDS)     

Ischemic reperfusion injury in rabbit spinal cord: protective effect of superoxide dismutase on neurological recovery and spinal infarction

The potential role of superoxide dismutase (SOD), a specific superoxide anion radical scavenger, in treating spinal cord ischemia was investigated in rabbits subjected to aortic occlusion for 20 min. SOD treatment, targeted to the early reperfusion period, reduced both motor dysfunction and incidence of spinal infarcts at 7 days after ischemia. Present results suggest that oxygen-derived free radicals play a role in the pathogenesis of infarcts developing in the spinal cord after ischemia and reperfusion injuries.     

The effect of boric acid on the development of chick embryos treated at an early stage: preliminary results]

10 mul of a 2% boric acid solution are injected in chick embryos at 28 hours of incubation. The nervous system is always affected in its anterior and middle region, with exencephaly and reduction in size of the neural tube. Microphtalmy is frequent. The posterior limbs can be likewise altered, leading sometimes to symelia. The histological study shows furthermore that the notochord is locally hypertrophic or missing, at the same level where the nervous system is altered.     

Conformational insights on the molecular recognition processes of carbohydrate molecules by proteins and enzymes: A 3D view by using NMR

This review focuses, in a non-exhaustive manner, on the essential structural and conformational features of protein–carbohydrate interactions and on some applications of NMR spectroscopy to deal with this topic from different levels of complexity.