Studies on chiasma frequency and distribution in two fertile men carrying reciprocal translocations; one with a t(9;10) karyotype and one with a t(Y;10) karyotype

Summary The frequency and distribution of chiasmata was investigated in two fertile carriers of reciprocal translocations, one with a 46,XY,t(9;10)(p22;q24) karyotype and one with a 46,X,-Y,+der(Y),t(Y;10)(q12;q24) karyotype. In both cases the chromosomes involved in the translocation showed an increase in chiasma frequency in comparison to karyotypically normal controls and in both cases this increase was localised, affecting only one interstitial segment of each translocation quadrivalent. In the t(9;10) case chiasmata appeared in substantial numbers in a novel location, the proximal two thirds of 9p, while in the t(Y;10) case chiasmata appeared in a conventional location, the medial region of 10q, but at an increased frequency. Furthermore there was evidence for inter-chromosomal effects in the t(9;10) case.     

Enkephalin immunoreactivity in iris nerves: Distribution in normal and grafted irides,persistence and enhanced fluorescence after denervations

Summary The morphology and distribution of nerve fibers showing enkephalin-like immunoreactivity was studied in rat and mouse iris whole mounts. In adult rat, a relatively dense network of varicose fibers was seen throughout the iris. Individual, long, usually smooth fibers were observed running together with non-fluorescent fibers in bundles. Positive nerve fibers were also seen in the ciliary body and the choroid membrane. The fluorescence intensity was normally low. No enkephalin-positive fibers were detected in adult mouse iris.Extirpation or lesioning either one or all the three ganglia known to supply the rat iris with nerve fibers, the superior cervical, the ciliary and the trigeminal ganglia, caused no detectable decrease in amount of enkephalin-positive fibers. However, in irides grafted to the anterior eye chamber of adult recipients, no enkephalin-positive fibers could be observed 2–12 days postoperatively, strongly suggesting that degeneration of these fibers had occurred. When iris grafts were left longer in the eye, nerve fibers with enkephalin-like immunoreactivity reappeared. An increased fluorescence intensity was observed both in the ipsilateral and contralateral iris following extirpation or lesioning all three ganglia and in the ipsilateral iris after extirpation of the ciliary ganglion. Three days after a systemic injection of capsaicin, which causes a permanent disappearance of substance P fibers, the same phenomenon was often observed. This raises the possibility of an interaction between the enkephalin-positive and the substance P fiber systems in the iris.The present experiments thus demonstrate a rich network of enkephalin immunoreactive nerve fibers in the rat iris originating outside the iris but apparently not in the ciliary, trigeminal or superior cervical ganglion.     

A sub-population of rat liver membrane-bound ribosomes that are detached in vitro by carcinogens and centrifugation.

The chemical-carcinogen-induced detachment of ribosomes from rat liver endoplasmic reticulum was studied in vitro. Incubation of postmitochondrial supernatant with 0.2 mM-diethylnitrosamine or N-2-acetylaminofluorene removed approx. 16% of membrane-bound ribosomes, measured as differences in RNA/protein values of membrane separated from unbound ribosomes by flotation. These ribosomes are also detached by exposure to high centrifugal forces (160000g) and are among those removed by NADPH-catalysed lipid peroxidation. Extensive lipid peroxidation prohibits any measurement. The ribosomes (polyribosomes) removed are not those detached from the membrane by exposure to high KC1 concentrations (loosely bound) or high KC1 concentrations in the presence of puromycin (tightly bound). It is concluded then that centrifugally labile and carcinogen-sensitive represent a previously unreported sub-population of membrane-bound ribosomes.     

Partial trisomy 1 due to a "shift" and probable location of the Duffy (Fy) locus.

Transposition of 1q31-1q32 from the q to p arm in a parent followed by crossing over resulted in a child with a duplication of this region. Concomitant C- and GTG-banding and genotyping were used to position the single crossover and to localize Fy to 1q2.     

The role of sodium-channel density in the natriferic response of the toad urinary bladder to an antidiuretic hormone

Summary Urinary bladders ofBufo marinus were depolarized, by raising the serosal K concentration, to facilitate voltage-clamping of the apical membrane. Passive Na transport across the apical membrane was then studied with near-instantaneous current-voltage curves obtained before and after eliciting a natriferic response with oxytocin. Fitting with the constant-field equation showed that the natriferic effect is accounted for by an increase in the apical Na permeability. It is accompanied by a small increase in cellular Na activity. Furthermore, fluctuation analysis of the amiloride-induced shot-noise component of the short-circuit current indicated that the permeability increase is not due to increased Na translocation through those Na channels which were already conducting prior to hormonal stimulation. Rather, the natriferic effects is found to be based on an increase in the population of transporting channels. It appears that, in response to the hormone, Na channels are rapidly recruited from a pool of electrically silent channels.     

Electron transfer reactions of cytochrome c confined within erythrocyte ghosts

We have prepared and characterized resealed erythrocyte ghosts in which the only discernible pigment is cytochrome c. The resealed ghosts have the normal orientation and are free of 'leaky' species; they are stable and can be maintained at 4 degrees C for many days without lysis. The internal cytochrome c participates in redox reactions with both soluble and insolubilized cytochrome c present externally, and with external cytochrome b5. No reaction was observed with plastocyanin, cytochrome c oxidase or NADPH-cytochrome c reductase. A study has been made of the reaction of the internal cytochrome c with the low molecular weight reductants, ascorbate and glutathione. Complex kinetics are observed with both reagents: with ascorbate the results are best explained by assuming the existence, in the membrane, of a redox-active species able to undergo dedimerization. A protein bound disulfide bond would satisfy the requirement.     

Measurement of the rates of protein synthesis in rabbits. A method for the estimation of rates of change in the specific radioactivities of free amino acids during continuous infusions.

1. A method is described by which, from analysis of terminal samples, the rate constants that define the changes in specific radioactivity of free amino acids during continuous infusions can be estimated. The method involves the infusion of 3H-labelled and 14C-labelled forms of an amino acid for different, but overlapping, periods. 2. The procedure was developed for infusions of proline and tyrosine into New Zealand White rabbits and the rate constants were determined for blood and muscle. 3. The rate constant for equilibrium of radioactive free proline was much lower in muscle than in blood, and indicated that a plateau condition may not be attained in muscle by the end of a 6 h infusion. 4. Comparison of the ratio of areas under the curves of estimated specific radioactivity plotted versus time with the 3H/14C ratio of bound amino acid in muscle protein suggested that radioactive proline and tyrosine may be incorporated preferentially from an extracellular rather than an intracellular source.     

The genetic structure of the kuwaiti population II: The distribution of Q-band chromosomal heteromorphisms

Summary The distribution of Q-band heteromorphisms in three Kuwaiti communities is reported. Of particular significance is the finding of large-Y segregating at a very high frequency (61.9%) in the Ajman tribesmen; and the absence of small-Y in the two tribal communities. The large variation in size of the Y-chromosome may reflect a unique cytogenetic feature of the inhabitants of the Arabian peninsula.