Mugil cephalus L.—a first British record and a further 5°N

The occurrence of a 29 mm juvenile Mugil cephalus in the Camel estuary at 50°30' N represents the first British record of this widespread tropical and subtropical species. Its origins, however, are obscure.     

Stereochemical control over Mn(II)-thio versus Mn(II)-oxy coordination in adenosine 5'-O-(1-thiodiphosphate) complexes at the active site of creatine kinase

The stereochemical configurations of the Mn(II) complexes with the resolved epimers of adenosine 5'-O-(1-thiodiphosphate) (ADP alpha S), bound at the active site of creatine kinase, have been determined in order to assess the relative strengths of enzymic stereoselectivity versus Lewis acid/base preferences in metal-ligand binding. Electron paramagnetic resonance (EPR) data have been obtained for Mn(II) in anion-stabilized, dead-end (transition-state analogue) complexes, in ternary enzyme-MnIIADP alpha S complexes, and in the central complexes of the equilibrium mixture. The modes of coordination of Mn(II) at P alpha in the nitrate-stabilized, dead-end complexes with each epimer of ADP alpha S were ascertained by EPR measurements with (Rp)-[alpha-17O]ADP alpha S and (Sp)-[alpha-17O]ADP alpha S. The EPR spectrum for the complex with (Rp)-[alpha-17O]ADP alpha S showed inhomogeneous broadening due to unresolved superhyperfine coupling from coordinated 17O at P alpha. By contrast, the EPR spectrum for Mn(II) in complex with (Sp)-[alpha-17O]ADP alpha S is indistinguishable from that obtained for a matched sample with unlabeled (Sp)-ADP alpha S. A reduction in the magnitude of the 55Mn hyperfine coupling constant in the spectrum for the complex containing (Sp)-ADP alpha S is indicative of Mn(II)-thio coordination at P alpha.(ABSTRACT TRUNCATED AT 250 WORDS)     

The fish community of an East African mangrove creek

The results of a beach seine survey of an East African mangrove creek are presented. The fish community of the creek is described and is compared with that of a nearby lagoonal site and with those described for other mangrove and estuarine systems. The species composition was found to differ substantially between the creek and the lagoon site, though diversity indices for the two areas were similar. Eighty-three species of teleost fish werecollected from the mangrove area of the creek. This number is considered high in relation to comparable studies and is attributed to the constant high salinity (approximately 35%o) measured throughout the study period. Approximately 90% of the fish caught were juveniles. Plankton sampling was also carried out and representatives of 21 fish families were collected as larvae within the creek. Catches from both beach seining and plankton sampling in the mangrove areas were dominated numerically by resident clupeid and gobiid species. The majority of species, however, were considered to have a widespread distribution as adults. A discrepancy between the catch composition of larvae and juveniles suggests that species that use the creek as a nursery area enter the system principally at a post-larval/ juvenile stage of development. No systematic spatial or temporal variation in the community structure was identified over the study period.     

Observation of manganese(II)-ligand superhyperfine couplings in complexes with proteins by electron spin-echo spectroscopy

Pulsed electron paramagnetic resonance spectroscopy has been used to detect Mn(II)-ligand superhyperfine couplings in complexes with creatine kinase and in the Mn(II) metalloprotein concanavalin A. Electron spin-echo envelopes from Mn(II), bound in these complexes, are modulated by superhyperfine interactions between Mn(II) and nearby, weakly coupled nuclear spins. The characteristic frequencies of the modulations were obtained by Fourier transformation of the three-pulse, spin-echo envelopes. In transition-state analogue complexes of creatine kinase (enzyme-MnIIADP-anion-creatine), superhyperfine interactions from the directly coordinated nitrogen of the thiocyanate ligand give envelope modulations. The source of the modulations was confirmed by measurements with the 14N and 15N forms of thiocyanate. On the other hand, the nitrogen of coordinated nitrate, which is two bonds removed from the paramagnetic center, does not produce detectable modulations. In spectra for Mn(II) concanavalin A, envelope modulations are detected due to the nitrogen of the coordinated histidine residue. Complexes prepared in 2H2O give strong signals due to weakly coupled 2H. For Mn(II)-doped single crystals of sodium pyrophosphate, signals are observed in the frequency domain spectra that are due to coupling from 31P. Phosphorus signals from the ADP ligand in complexes with creatine kinase show approximately the same coupling constant but have a much broader line width.     

Schistosoma mansoni: complexity of antigenic and nonantigenic surface polypeptides

Two-dimensional gel analysis of the surface polypeptides of the schistosomula stage of Schistosoma mansoni resolved a complex pattern of approximately 20 polypeptides. The majority of these were identified as immunogenic since they were immunoprecipitated with antisera from chronically infected mice and from mice vaccinated with irradiated cercariae. However, several major surface polypeptides were not immunoprecipitated by sera from infected or immune mice and were presumed to be nonantigenic.     

31P nuclear magnetic resonance study of phosphoribosyldiphosphate and its interaction with magnesium ions

31P NMR has been used to study phosphoribosyldiphosphate (P-Rib-PP) over a wide range of pH values, both in the absence and presence of MgCl2. In the absence of MgCl2, the chemical shift variations of the three 31P nuclei in the molecule, over the pH range 4 to 9, were found to be largest for the terminal 1-diphosphate (1P beta) oxyanion and the 5-phosphate (5P) moiety. Apparent pK alpha values of approximately 6.1 and 6.3 were estimated for protonation of the 1P beta and 5P groups, respectively. Variations in the apparent pK alpha values associated with 1P beta and 5P oxyanions in the presence of various concentrations of MgCl2 were consistent with P-Rib-PP having two independent metal ion binding sites with different affinities for Mg2+ ions. The binding of Mg2+ reduced the apparent pK alpha of the 1P beta moiety by approximately 1.6 units and the apparent pK alpha of the 5P group by approximately 0.7 unit. This behavior is analogous to the situation reported for the terminal phosphooxyanion of ADP and observed for the phosphate group of ribose 5-phosphate, respectively. In the presence of an equimolar concentration of added MgCl2, the 1P alpha and 1P beta resonances of P-Rib-PP were shifted downfield and the 31P-31P coupling constant was decreased. Changes in both these parameters were very similar to those reported for the MgADP- complex. The observed chemical shifts and spin-spin coupling constants suggest that the diphosphate and monophosphate moieties of P-Rib-PP act as independent binding sites for Mg2+ in a manner similar to the phosphooxyanion groups of ADP and ribose 5-phosphate, respectively.     

Parenting Practices at 24 to 47 Months and IQ at Age 8: Effect-Measure Modification by Infant Temperament

Cognitive development might be influenced by parenting practices and child temperament. We examined whether the associations between parental warmth, control and intelligence quotient (IQ) may be heightened among children in difficult temperament. Participants were from the Avon Longitudinal Study of Parents and Children (n = 7,044). Temperament at 6 months was measured using the Revised Infant Temperament Questionnaire and classified into ‘easy’ and ‘difficult’. Parental warmth and control was measured at 24 to 47 months and both were classified into 2 groups using latent class analyses. IQ was measured at 8 years using the Wechsler Intelligence Scale for Children and dichotomized (<85 and ≥85) for analyzing effect-measure modification by temperament. Linear regression adjusted for multiple confounders and temperament showed lower parental warmth was weakly associated with lower IQ score [β = -0.52 (95% CI 1.26, 0.21)], and higher parental control was associated with lower IQ score [β = -2.21 (-2.95, -1.48)]. Stratification by temperament showed no increased risk of having low IQ in temperamentally difficult children [risk ratio (RR) = 0.97 95% CI 0.65, 1.45)] but an increased risk among temperamentally easy children (RR = 1.12 95% CI 0.95, 1.32) when parental warmth was low. There was also no increased risk of having low IQ in temperamentally difficult children (RR = 1.02 95% CI 0.69, 1.53) but there was an increased risk among temperamentally easy children (RR = 1.30 95% CI 1.11, 1.53) when parental control was high. For both parental warmth and control, there was some evidence of negative effect-measure modification by temperament on the risk-difference scale and the risk-ratio scale. It may be more appropriate to provide parenting interventions as a universal program rather than targeting children with difficult temperament.