On the chemical basis of chromosome banding patterns.

A comparative study of the staining characteristics of four reagents for human chromosomes has been carried out. The four reagents are: (I) quinacrine mustard, as an alkylating agent, (II) the dihydroxy derivative of quinacrine mustard, (III) quinacrine, and (IV) 9-amino-6-chloro-2-methoxyacridine. The last reagent does not possess the amino substituted side chain even though it has the same intercalating nucleus. Comparison of the first three compounds in their staining and banding behavior suggested the initial step leading to banding may be the displacement of the nucleoprotein sites in hcromosomes. The Q and G banding could be blocked experimentally by treating the chromosome preparation with dimethylamine solution. This result may suggest that these sites have weaker basic proteins (nonhistone proteins?). The use of compound IV, which does not have the side chain in the molecule but does have the same intercalating chromophore, did not lead to banding and gives indirect support to this hypothesis. A combined use of compound IV and quinacrine may be useful for the determination of total DNA vs. banding DNA.     

Vocalizations of Australian hopping mice (Rodentia: Notomys)

The four species of hopping mouse studied, N. alexis, N. cervinus, N. fuscus and N. mitchellii , were found to have a basic repertoire of eight more or less discrete vocalizations: three in the young—the calls produced in the nest, ultrasonic pipping given when removed from the nest and a high intensity (pain) squeal—and five in the adult—a low intensity pip given during mutual grooming, a high intensity (pain) squeal, a medium intensity squeak given when "annoyed", twittering given during aggressive chases and ultrasonic pipping given during non-aggressive encounters. The calls of the different species varied in structure and in pitch. No vocalizations were associated with threat or fighting. Calls given in the nest by suckling young are well developed and the intensity of such calls appears to mirror the general motivational state of the caller. It is suggested that these calls may act to maintain maternal behaviour in the mother.     

Anion activation of monkey muscle creatine kinase

Creatine kinase from rhesus monkey skeletal muscle is activated by acetate and other short chain fatty acids. Activation is associated with lower Km and higher Vmax values at less than saturating substrate concentrations but does not occur when both substrates are saturating. No co-operativity between subunits is evident in the activation process. It appears that acetate promotes the mutual enhancement by substrates in their binding by inducing the optimum enzyme conformation normally associated with substrate saturation. Conservation of this activation effect through the evolution of the phosphagen kinases implies that it may well be of physiological significance.     

Conformational Space Comparison of GnRH and lGnRH-III using Molecular Dynamics,Cluster Analysis and Monte Carlo Thermodynamic Integration

Abstract

The conformational space available to GnRH and 1GnRH-III was compared using 5.2 ns constant temperature and pressure molecular dynamics simulations with explicit TIP3P solvation and the AMBER v. 5.0 force field. Cluster analysis of both trajectories resulted in two groups of conformations. Results of free energy calculations, in agreement with previous experimental data, indicate that a conformation with a turn from residues 5 through 8 is preferred for GnRH in an aqueous environment. By contrast, a conformation with a helix from residues 2 through 7 with a bend from residues 6 through 10 is preferred for 1GnRH-III in an aqueous environment. The side chains of His² and Trp³ in 1GnRH-III occupy different regions of phase space and participate in weakly polar interactions different from those in GnRH. The unique conformational properties of 1GnRH-III may account for its specific anti cancer activity.     

Differential Effects of AGS3 Expression on D2L Dopamine Receptor-Mediated Adenylyl Cyclase Signaling

Activator of G protein signaling 3 (AGS3) binds Gα_i subunits in the GDP-bound state, implicating AGS3 as an important regulator of Gα_i-linked receptor (e.g., D2 dopamine and μ-opioid) signaling. We examined the ability of AGS3 to modulate recombinant adenylyl cyclase (AC) type 1 and 2 signaling in HEK293 cells following both acute and persistent activation of the D_2L dopamine receptor (D_2LDR). AGS3 expression modestly enhanced the potency of acute quinpirole-induced D_2LDR modulation of AC1 or AC2 activity. AGS3 also promoted desensitization of D_2LDR-mediated inhibition of AC1, whereas desensitization of D_2LDR-mediated AC2 activation was significantly attenuated. Additionally, AGS3 reduced D_2LDR-mediated sensitization of AC1 and AC2. These data suggest that AGS3 is involved in altering G protein signaling in a complex fashion that is effector-specific and dependent on the duration of receptor activation.     

Morphological variation and heritability in three Melanesian populations: A multivariate approach

In two previous papers Giles, Walsh and Bradley ('66) and Giles, Wyber and Walsh ('70) have shown that the inhabitants of three adjacent villages on the edge of the Markham Valley in New Guinea have significant heterogeneity in all blood group frequencies tested. The language, environment, culture, and ancestry of these people are essentially identical. The differences in the blood group frequencies were attributed to genetic drift and particularly to founder effect. In this paper the anthropometric data from these villages are analysed. Analysis of variance shows that 50% of the traits are significantly different. Multiple discriminant analysis demonstrates that the villages can be significantly separated morphologically. The heritability of each trait is determined using an analysis of within and among sibship variation. Traits with strong “genetic” components of variation and traits with strong “environmental” components contribute significantly to the morphological heterogeneity among the villages. Some speculations are presented on the cause of the “genetic” component of morphological variation.