Ionic Requirements for the Specific Binding of [3H]GBR 12783 to a Site Associated with the Dopamine Uptake Carrier

At 0°C, when Na⁺ was the only cation present in the incubation medium, increasing the Na⁺ concentration from 3 to 10 mM enhanced the affinity of [³H]l-[2-(di-phenylmethoxy)ethyl]-4-(3-phenyl-2-propenyl)piperazine ([³H]GBR 12783) for the specific binding site present in rat striatal membranes without affecting the 5_max. For higher Na⁺ concentrations, specific binding values plateaued and then slightly decreased at 130 mM Na⁺. In a 10 mM Na⁺ medium, the K_D and the B_max were, respectively, 0.23 nM and 12.9 pmol/mg of protein. In the presence of 0.4 nM [³H]GBR 12783, the half-maximal specific binding occurred at 5 mM Na⁺. A similar Na⁺ dependence was observed at 20°C. Scatchard plots indicated that K⁺, Ca²⁺, Mg²⁺, and Tris⁺ acted like competitive inhibitors of the specific binding of [³H]GBR 12783. The inhibitory potency of various cations (K⁺, Ca²⁺, Mg²⁺, Tris⁺, Li⁺ and choline) was enhanced when the Na⁺ concentration was decreased from 130 to 10 mM. In a 10 mM Na⁺ medium, the rank order of inhibitory potency was Ca²⁺ (0.13 mM) > Mg²⁺ > Tris⁺ > K⁺ (15 mM). The requirement for Na⁺ was rather specific, because none of the other cations acted as a substitute for Na⁺. No anionic requirement was found: Cl^-, Br^-, and F^- were equipotent. These results suggest that low Na⁺ concentrations are required for maximal binding; higher Na⁺ concentrations protect the specific binding site against the inhibitory effect of other cations.     

A minority of 46,XX true hermaphrodites are positive for the Y-DNA sequence including SRY

Summary A total of 30 cases of 46,XX true hermaphroditism was analysed for Y-DNA sequences including the recently cloned gene for male testis-determination SRY. In 3 cases, a portion of the Y chromosome including SRY was present and, in 2 cases, was localised, to Xp22 by in situ hybridisation. Since previous studies have shown that the majority of XX males are generated by an X-Y chromosomal interchange, the Xp22 position of the Yp material suggests that certain cases of hermaphroditism can arise by the same meiotic event. The phenotype in the 3 SRY-positive cases may be caused by X-inactivation resulting in somatic mosaicism of testis-determining factor expression giving rise to both testicular and ovarian tissues. Autosomal or X-linked mutation(s) elsewhere in the sex-determining pathway may explain the phenotype observed in the remaining 27 SRY-negative cases.     

The effects of extracellular matrix (ECM) proteins on the attachment of Pneumocystis carinii to lung cell lines in vitro.

Pneumocystis carinii cells labeled with fluorescein isothiocyanate were co-cultured with tissue culture cells. Measurements of attachment was determined by the tissue culture cell fluorescence after washing out the P. carinii organisms. The effects of the extracellular matrix proteins, laminin and fibronectin, on the binding of P. carinii onto the monolayer of cultured cells were investigated for better understanding of organism-cell interactions. The internalization of P. carinii by MRC5 cells was observed.     

Direct molecular analysis of the fragile X syndrome in a sample of Egyptian and German patients using non-radioactive PCR and Southern blot followed by chemiluminescent detection

Molecular genetic analysis of individuals from 6 Egyptian and 33 German families with fragile X syndrome and 240 further patients with mental retardation was performed applying a completely non-radioactive system. The aim of our study was the development of a non-radioactive detection method and its implementation in molecular diagnosis of the fragile X syndrome. Furthermore, we wanted to assess differences in the mutation sizes between Egyptian and German patients and between Egyptian and German carriers of a premutation. Using non-radioactive polymerase chain reaction (PCR), agarose gel electrophoresis and blotting of the PCR products, followed by hybridisation with a digoxigenin-labelled oligonucleotide probe (CGG)₅ and chemiluminescent detection, we identified the fragile X full mutation (amplification of a CGG repeat in the FMR-1 gene ranging from several hundred to several thousand repeat units) in all patients. We observed no differences in the length of the CGG repeat between the Egyptian and German patients and carriers, respectively. However, in one prenatal diagnosis, we detected only one normal sized allele in a female fetus using the PCR-agarose assay, whereas Southern blot analysis with the digoxigenin labelled probe StB 12.3 revealed presence of a full mutation. Our newly established nonradioactive genomic blotting method is based on the conventional radioactive Southern blot analysis. Labelling of the probe StB 12.3 with digoxigenin via PCR allowed the detection of normal, premutated and fully mutated alleles. For exact sizing of small premutated or large normal alleles, we separated digoxigenin labelled PCR products through denaturing poly-acrylamide gelelectrophoresis (PAGE) and transfered them to a nylon membrane using a gel dryer. The blotted PCR-fragments can easily be detected with alkaline phosphate-labelled anti-digoxigenin antibody. The number of trinucleotide repeat units can be determined by scoring the detected bands against a digoxigenated M13 sequencing ladder. Our newly developed digoxigenin/chemiluminescence approach using PCR and Southern blot analysis provides reliable results for routine detection of full fragile X mutations and premutations.     

Complexes of vitamin B6, part VII: Ternary complexes of cobalt(II), nickel(II), and copper(II) involving pyridoxamine and some amino acids

The stability constants of the ternary Cu(II), Ni(II), and Co(II) complexes containing pyridoxamine (PM) and as a second ligand (L) glycine, DL-alanine, DL-valine, and β-phenylalnine were determined by pH-metric titration in 0.50 M KNO₃ at 30°C. The corresponding constants of the equilibrium, log X, are greater than would be expected for purely statistical reasons (log X = 0.6), except for few complex cases of Co(II). It has been also concluded that amino acids compete more than pyridoxamine for Ni(II) and Co(II) through the formation of 1:2:1:0 species rather than 2:1:1:0 of PM⁻:L⁻:M²⁺:H⁺.     

Caligus tunisiensis n. sp. (Copepoda: Caligidae) parasitic on the painted comber Serranus scriba (L.) (Perciformes: Serranidae) from the Mediterranean Sea,off the Tunisian coast

Systematic Parasitology - A new species of parasitic copepod, Caligus tunisiensis n. sp. (Caligidae), is described based on two female specimens collected from the gills of the painted comber,...     

Dog Obesity: Can Dog Caregivers' (Owners') Feeding and Exercise Intentions and Behaviors Be Predicted From Attitudes?

Dog obesity is a common nutritional disorder affecting up to 40% of the companion animal (pet) dog population in Australia and other developed nations. A clear understanding of factors determining relevant caregiver (owner) behaviors underpins effective treatment for this disorder. The theory of planned behavior can be used to understand factors contributing to human behavior. This article describes research informed by this theory. The research examined relationships between owners' behavioral beliefs and barriers, normative beliefs and perceptions of control, owners' feeding and exercise behaviors toward their dogs, and the body condition scores (BCSs) of dogs. The study recruited a sample of 182 dog and owner dyads. The researcher independently assessed BCSs. Owners completed a questionnaire measuring relevant feeding and exercise beliefs and behaviors. This revealed significant correlations between many psychological variables and BCSs and between psychological variables and specific owner behaviors: for example, the relationship of low levels of intentions to feed appropriately to ambivalent beliefs toward feeding appropriately and low perceived control. Careful consideration of the specific variables identified will permit the development of more effective interventions.     

Base Pairing at the Stem-loop Junction in the SL1 Kissing Complex of HIV-1 RNA: A Thermodynamic Study Probed by Molecular Dynamics Simulation

Abstract

The thermodynamics of the opening/closure process of a GC base pair located at the stem-loop junction of the SL1 sequence from HIV-1_Lai genomic RNA was investigated in the context of a loop-loop homodimer (or kissing complex) using molecular dynamics simulation. The free energy, enthalpy and entropy changes for the closing reaction are 0 kcal·mol^?1, ?11 kcal·mol^?1and ?0.037 kcal·mol^?1-K^?1 at 300° K respectively. Furthermore it is found that the free energy change is the same for the formation of a 11 nucleotide loop closed with UG and for the formation of a 9 nucleotide loop closed with GC. Our study evidences the high flexibility of the nucleotides at the stem-loop junction explaining the weak stability of this structure.