The Receptor-Mediated Activation of Tyrosine Hydroxylation in the Superior Cervical Ganglion of the Rat

The addition of carbachol to superior cervical ganglia causes a rapid increase in tyrosine hydroxylation in situ. The increase occurs in ganglia from both newborn and adult animals, and in ganglia from animals pretreated with reserpine. The increase is not due to increased transport of the substrate. The increase is dependent upon the presence of calcium, and is additive to the stimulation produced by dibutyryl cyclic AMP. The stimulation seems specific for tyrosine hydroxylation; dopamine beta-hydroxylation is not increased. Preincubation experiments suggest that the carbachol-induced stimulation is due to a change in the availability of, or the affinity of the enzyme for, reduced pterin cofactor. The stimulation is inhibited by atropine and also by low concentrations of phenoxybenzamine or haloperidol, which suggests that it is caused by an action of carbachol on the interneurons in the ganglia.     

Stratigraphic occurrences and vegetational patterns of Pennsylvanian pteridosperms in Euramerican coal swamps

The vegetation of many Euramerican coal swamps is known from coal-ball peats in the tropical rainy zone across the paleocontinent of Laurussia in the Upper Carboniferous. The stratigraphic occurrences of coal balls in Europe (lower Westphalian) and in North America (upper Westphalian and lower Stephanian) are largely complementary and a revised correlation chart is given. Quantitative analyses of the vegetation from these autochthonous peats are combined with coal palynology to determine on overview of swamp vegetation patterns during the Westphalian and early Stephanian. In comparison to the dominance and great diversity of pteridosperms in the Upper Carboniferous compression floras, seed ferns were minor to subdominant elements in the coal-ball peats. The quantitative composition of organ assemblages of the principal pteridosperms is given with stratigraphic occurrences of Medullosa and Sutcliffia (Medullosaceae), Heterangium, Lyginopteris, Microspermopteris, and Schopfiastrum (Lyginopteridaceaea) and Callistophyton (Callistophytaceae). The major peat contributors among pteridosperms are Lyginopteris (?90%) in the Westphalian A and Medullosa (?95%) in the Westphalian D and Stephanian. Lyginopteris became extinct in the early Westphalian B and Medullosa became abundant during the Westphalian C–D transition and a subdominant in the Stephanian contributing 13–21% of the permineralized peats. Paleoecological interpretations indicate that medullosan trees were most abundant but patchy in distribution in drier swamp stages with enriched nutrients and near major channels in swamps during the Westphalian D. It is suggested that the swamp pteridosperms are probably quite similar to or identical with some of the representatives in the more diverse compression floras. The evolution and diversity noted in swamp pteridosperms are considered principally the product of adjacent lowland communities which repeatedly introduced seeds into the wetlands. The swamp pteridosperms exhibit the greatest fluctuation in abundance (biomass) from site to site in the same coal, probably the highest level of diversity and the only steady pattern of increase in importance during the Late Carboniferous with the possible exception of the Westphalian B–C interval. The close relationships inferred between swamp pteridosperms and their lowland seed sources are also compatible with the frequent association of tree ferns and seed ferns during the Westphalian D and in the Stephanian when these two kinds of frond-bearing trees formed most of the vegetation in both lowland and swamp environments.     

Use of the smith degradation in the study of the branching pattern in the complex-type carbohydrate units of glycoproteins

The site of substitution of the peripheral branches on the core mannose-residues in the complex-type carbohydrate units of glycoproteins has been studied by Smith degradation. By using glycopeptides of known structure, it is shown that the site of attachment of the (1→4)-linked, third branch to the mannose core in tri- and tetra-antennary structures may be conveniently demonstrated by this technique. A critical factor was found to be the concentration of acid used for cleavage of the periodate-oxidized product. This finding could explain discrepancies concerning the previously published structures of fetuin glycopeptides. The technique was applied for study of the branching pattern in human transferrin, porcine thyroglobulin, and rat plasma and brain glycoproteins. The results support the concept that, in glycoproteins from most sources, the third (1→4)-linked branch is attached to the (1→3)-linked mannose residue of the core portion in the complex-type structures. An indication for a novel type of branching pattern in human transferrin was, however, also obtained.     

Induction of tyrosine aminotransferase by pyridoxine in Drosophila hydei

Salivary glands incubated in various concentrations of pyridoxine (Vitamin B₆) show increasing tyrosine aminotransferase (TAT) activity at concentrations up to 10^–5 M and then decreasing activity up to 10^–2 M but in all cases the activity is greater than that of the controls. This increase in activity is demonstrable for up to 6 h, the longest period tested, and is dependent on the synthesis of new mRNA. A similar increase in TAT activity is observed in salivary glands subjected to heat shock. Antibodies prepared against purified tyrosine aminotransferase precipitate a peptide of the same molecular weight (40 KD) as that induced by pyridoxine.     

Using genetic variation to disentangle the complex relationship between food intake and health outcomes

Diet is considered as one of the most important modifiable factors influencing human health, but efforts to identify foods or dietary patterns associated with health outcomes often suffer from biases, confounding, and reverse causation. Applying Mendelian randomization in this context may provide evidence to strengthen causality in nutrition research. To this end, we first identified 283 genetic markers associated with dietary intake in 445,779 UK Biobank participants. We then converted these associations into direct genetic effects on food exposures by adjusting them for effects mediated via other traits. The SNPs which did not show evidence of mediation were then used for MR, assessing the association between genetically predicted food choices and other risk factors, health outcomes. We show that using all associated SNPs without omitting those which show evidence of mediation, leads to biases in downstream analyses (genetic correlations, causal inference), similar to those present in observational studies. However, MR analyses using SNPs which have only a direct effect on the exposure on food exposures provided unequivocal evidence of causal associations between specific eating patterns and obesity, blood lipid status, and several other risk factors and health outcomes.     

Maternal transfer of strain-specific immunity in an invertebrate

The most celebrated component of the vertebrate immune system is the acquired response in which memory cells established during primary infection enhance the proliferation of antibodies during secondary infection. Additionally, the strength of vertebrate acquired immune responses varies dramatically depending on the infecting pathogen species or on the pathogen genotype within species. Because invertebrates lack the T-cell receptors and Major Histocompatibility Complex (MHC) molecules that mediate vertebrate adaptive immune responses, they are thought to lack adaptive immunity and be relatively unspecific in their interactions with pathogens. With only innate immunity, invertebrate hosts are believed to be nai;ve at each new encounter with pathogens. Nevertheless, some forms of facultative immunity appear to be important in insects; some individuals have enhanced immunity due to population density, and some social insects benefit when their nest-mates have been exposed to a pathogen or pathogen mimic (; see for a predation example.) Here we provide evidence for acquired strain-specific immunity in the crustacean Daphnia magna infected with the pathogenic bacteria Pasteuria ramosa. Specifically, the fitness of hosts was enhanced when challenged with a bacterial strain their mother had experienced relative to cases when mother and offspring were challenged with different strains.     

A 96-well DNase I footprinting screen for drug–DNA interactions

The established protocol for DNase I footprinting has been modified to allow multiple parallel reactions to be rapidly performed in 96-well microtitre plates. By scrutinizing every aspect of the traditional method and making appropriate modifications it has been possible to considerably reduce the time, risk of sample loss and complexity of footprinting, whilst dramatically increasing the yield of data (30-fold). A semi-automated analysis system has also been developed to present footprinting data as an estimate of the binding affinity of each tested compound to any base pair in the assessed DNA sequence, giving an intuitive ‘one compound–one line’ scheme. Here, we demonstrate the screening capabilities of the 96-well assay and the subsequent data analysis using a series of six pyrrolobenzodiazepine-polypyrrole compounds and human Topoisomerase II alpha promoter DNA. The dramatic increase in throughput, quantified data and decreased handling time allow, for the first time, DNase I footprinting to be used as a screening tool to assess DNA-binding agents.