A multigene family for the vasopressin-like hormones? Identification of mesotocin,lysipressin and phenypressin in Australian macropods

Mesotocin ([Ile8]-oxytocin), lysipressin ([ Lys8]-vasopressin) and phenypressin ([Phe8]-vasopressin) have been identified in the western gray kangaroo (Macropus fuliginosus) as well as four other macropodids. Lysipressin and phenypressin, which differ by the amino acids in positions 2 (Tyr/Phe) and 8 (Lys/Arg) are likely products of two separate vasopressin-like genes. It is assumed that arginine vasopressin found in most mammals is the product of two identical genes which can be revealed in some species by differential mutations as seen usually in marsupials. The duality can also be revealed by differential mutations in another domain of the precursors, such as the neurophysin (MSEL-neurophysin), as observed in the ox.     

Leucostasis, an underestimated cause of death in leukaemia

Massive sludging of leukaemic cells in blood vessels is a frequent and often lethal complication of leukaemia. In a retrospective clinicopathological study on the causes of death in 52 patients with acute myeloid leukaemia and myeloproliferative disease, pulmonary leucostasis was found in 40% of the patients. In many of these patients the vessels of the heart, brain and testes were also involved. In search for signs and symptoms specific for leucostasis, the clinical records of the 21 patients with leucostasis (the study group) were compared to those of 20 patients without leucostasis (the control group). Dysfunction of the organs most affected by leucostasis, namely lungs, heart and brain, was found more often in the study group than in the controls, but the combination of unexplained fever with cardiopulmonary and/or central nervous system failure occurred almost exclusively and in half of the patients with leucostasis. Leucostasis occurs predominantly, but not exclusively, in patients with high leucocyte counts, and especially, but again not exclusively, when the leucocyte counts rise sharply.     

Changes in fiber composition of soleus muscle during rat hindlimb suspension

Chronic reduction of gravitational load in the rear limbs of rats to simulate the influence of near-zero gravity in skeletal muscles has been shown previously to elicit atrophy in the soleus muscle. Use of this model by the present investigation indicates that soleus atrophy was characterized by a decline in the number of fibers in groups that contained the slow isoenzyme of myosin and which were classified as type I from intensity of staining to myofibrillar actomyosin adenosinetriphosphatase (ATPase) and to NADH tetrazolium reductase. Furthermore total fiber number was not changed, whereas fibers containing the intermediate isoenzyme and those classified as type IIa increased. There results could be explained by either a change in the composition within existing fibers or a simultaneous loss of slow fibers and de novo synthesis of intermediate and fast fibers. Evidence for transformation included an absence of embryonic or neonatal myosin in muscles from suspended rats and the constant fiber number that was unchanged by 4 wk of suspension. Furthermore although fiber areas of both groups of type I and IIa fibers declined during suspension, variability of the fiber areas within each group did not increase.     

Translational discrimination between the four RNAs of alfalfa mosaic virus. A quantitative evaluation

In an attempt to relate the translational characteristics of alfalfa mosaic virus (A1MV) RNAs to their structure [Ravelonandro et al. (1983) Nucleic Acids Res. 11, 2815-2826; Gehrke et al. (1983) Biochemistry 22, 5157-5164] we measured the relative affinities (discrimination ratios) of these RNAs for the initiation complex, in the wheat germ extract and in the nuclease-treated reticulocyte lysate, using a competition method designed by Brendler et al. [(1981) J. Biol. Chem. 256, 11747-11754]. As a prerequisite of this study we ascertained that the molecular mass distribution of the translation products was independent of RNA concentration in both translation systems. In the wheat germ extract the discrimination ratios are very similar for two strains of A1MV (S and B) which differ mainly by the presence (strain S) or absence (strain B) of a stable 5'-proximal hairpin. Hence this structure has no bearing on discrimination. Taking the affinity of RNA 3 as reference, the following orders of magnitude are found for the affinities of the different RNAs in the wheat germ: RNA 3, 1.0; RNA 1, 10; RNA 2, 60; RNA 4, 150. In the reticulocyte lysate the discrimination ratios are not significantly different from the wheat germ. Thus it seems that the mechanism of discrimination is essentially the same in the two translation systems, despite a difference in rate-limitation.     

Influence of the composition of the fusion medium on the yield of electrofused yeast hybrids

Abstract Electrofusion between cells of yeast strains with different genetic markers in isotonic sorbitol solutions leads to high yields of hybrids when 0.1 mM Ca²⁺ and 0.5 mM Mg²⁺ salts are aded. On average, 1000–2000 hybrids are obtained when electrofusion is performed (in a helical chamber) compared to a yield of about 40–120 in the absence of these bivalent cations. A further increase in yield can be achieved by the addition of 1 mg/ml albumin, which results in up to 4000 hybrids per experimental run. The entire fusion process leads to very reproducible results in the presence of these substances.     

Escherichia coli RecBC pseudorevertants lacking chi recombinational hotspot activity

Pseudorevertants of an Escherichia coli exonuclease V (RecBC enzyme)-negative mutant have been isolated after ethyl methane sulfonate mutagenesis of a recC73 (presumed missense) mutant. The remedial mutations in each of the four pseudorevertants studied in detail map and complement as recC mutations. By several criteria, such as recombination proficiency, support of phage growth, RecBC nuclease activity, and cell viability, the pseudorevertants appear to have regained partially or completely various aspects of RecBC activity. However, chi recombinational hotspots, which stimulate exclusively the RecBC pathway of recombination, have no detectable activity in lambda vegetative crosses in the pseudorevertants. The properties of these mutants, in which the RecBC pathway of recombination is active yet in which chi is not active, are consistent with the hypothesis that wild-type RecBC enzyme directly interacts with chi sites; alternatively, the mutants may block or bypass the productive interaction of another recombinational enzyme with chi.