Transforming potential of a myc-containing variant of feline leukemia virus in vitro in early-passage feline cells.

We studied a naturally occurring variant of feline leukemia virus (FeLV) in which the oncogene myc has substituted for a portion of the viral structural genes (myc-FeLV). myc-FeLV was rescued by replication in the presence of FeLV as helper, and its biological activity was examined in early-passage feline cells in vitro. Infection of leukocytes from peripheral blood, spleen, or thymus, or of kitten fibroblasts did not immortalize these cells or alter them morphologically. Northern blot (RNA blot) analysis of virion RNA prepared from the supernatant of infected cells demonstrated the 8.2-kilobase genome of FeLV, but did not demonstrate the 5.0-kilobase genome of myc-FeLV. Apparently, the myc-FeLV genome was lost in the absence of the selective pressure of transformation. In contrast, infection of embryonic fibroblasts with myc-FeLV(FeLV) rendered these cells capable of greatly increased, if not infinite, proliferative potential. The cells were morphologically altered compared with controls and were only loosely adherent to the substrate. The cells failed to proliferate in semisolid medium and did not form tumors when inoculated subcutaneously into athymic mice. Blot analyses demonstrated the presence and expression of integrated proviral DNAs of both FeLV and myc-FeLV in these cells. They appear, then, to represent cells partially transformed by infection with myc-FeLV(FeLV). The action of feline v-myc in early-passage cells in vitro was compared to that of avian v-myc.     

3'-5' cyclic-guanosine monophosphate increase in rat brain hippocampus after gamma-hydroxybutyrate administration. Prevention by valproate and naloxone

An increase (123%) of cyclic GMP (cGMP) was observed in the hippocampus of the rat killed by microwave irradiation 45 min after administration of 500 mg/kg gamma-hydroxybutyrate (GHB) IP. This increase is time and dose dependent. No modification in cyclic nucleotide content was observed in striatum and in cerebellum. As the role of GHB has been implicated in neurotransmission, the fact that this compound increases cyclic GMP accumulation in hippocampus in vivo may represent a mechanism by which the actions of GHB are mediated at the cellular level. Valproate (400 mg/kg) or naloxone (10 mg/kg) pretreatment completely abolish the cGMP increase due to GHB. A GABAergic and/or opiate phenomenon may be involved in the mechanism of GHB induced increase of cGMP.     

The association between spontaneous pyelonephritis and maturity-onset diabetes mellitus in male MM mice

Blood glucose and glucose tolerance tests demonstrated that many male MM mice are diabetic. Serial urine sampling showed that the diabetes occurred only in mature MM males and consisted of a single self-limiting episode. Histological examination of the pancreas, together with measurements of body weight, glycosylated haemoglobin and plasma insulin, revealed that the diabetes was of the maturity-onset insulin-resistant type. Bacteriological examination of the urine samples showed that urinary tract infection, a known feature of male MM mice, occurred in the diabetics but only after the onset of hyperglucosuria. It was concluded that the high urinary glucose levels of diabetic MM males are of prime importance in the aetiology of the renal infection which occurs rarely in non-diabetic MM males or in other strains in the colony. An infectious aetiology for the diabetes per se was excluded by the existence of diabetes in germfree MM males.     

Antitrypanosomal action of cis-diamminedichloroplatinum (II) analogs

The present report deals with the alterations produced by cis-diamminedichloroplatinum (II) (DDP), and 2 of its analogs: cis-Pt(II)(tranylcypromine)2Cl2 and cis-Pt(II)(benzothiazole)2Cl2 in cultured epimastigote forms of Trypanosoma cruzi. Studies have been performed at the ultrastructural level and the inhibitory effect of these complexes on macromolecule synthesis, evaluated by 3H-thymidine, 3H-uridine, and 3H-leucine incorporation, has been investigated. DDP at concentrations of 50 and 100 micrograms/ml does not inhibit significantly the incorporation of radioactive precursors, but a clear decrease was observed with the 2 analogs. Eight hours of treatment at a concentration of 10 micrograms/ml rendered in all 3 cases an increase in autophagic vacuoles and lipids as well as an abnormal condensation of the nucleus chromatin.     

The number of species of rodent coccidia and of other protozoa

About 447 species of coccidia have been named from the 1687 living, known species of rodents; 207 host species, 92 host genera, and 15 host families are represented; this is about 12% of the known species of rodents. About 4600 species of apicomplexan protozoa have been named. Assuming that the same proportion of the total number of apicomplexan species has been named as of the coccidian species, there must actually be about 38,333 species of apicomplexan protozoa. There are 5.4 times as many protozoan genera as of apicomplexan genera. Assuming that the number of species in each genus is the same for all the protozoa as it is for the Apicomplexa, there may actually be 206,998 species of protozoa. This may be too conservative an estimate. Based on other criteria, an estimate of over 20 million species could be made.     

ARAGONITE CRYSTALS IN SPIROGYRA SP. (CHLOROPHYTA)

Intracellular crystals of aragonite have been identified by selected area electron diffraction (SAED) in a species of the freshwater filamentous alga Spirogyra from the Thames River, Ontario, Canada. The crystals are 2 to 24 μm in diameter, and characterized by a unique cross-shaped morphology, in which needle-like, or prismatic outgrowths develop from a common axis. Crystals may be dispersed throughout filaments, but tend to cluster as aggregates towards the centre .     

Biochemical investigation of tissue growth: towards definition of "standard" tissue samples

This paper presents an animal model [the kangaroo], a quantitative anatomical dissection procedure, and a mathematical model [two-phase linear regression] which illustrate that body tissues grow at varying rates relative to each other. An argument is developed that biochemists interested in tissue chemical activity need to be able to sample tissue of known [predicted] growth rate. It is assumed that the ability to select, say muscle tissue samples, from any one animal at a stage of its growth where the individual selected pieces of tissue have known [predicted] low, average and high growth rates would allow comparisons to be made between the sampled tissues that may elucidate the underlying biochemical mechanisms involved in the growth process. It is asserted that to establish standards for tissue samples used in biochemical growth studies, the growth rate of the sampled tissue should be one of the criteria incorporated into the definition of what is "standard" for a tissue sample.     

The probability with which EMS-initiated mutagenic lesions generate mutations in CHO cells

In this note we distinguish between multiple mutations affecting a given locus which are generated at separate error-prone lesions and multiple independent mutations generated at a single error-prone lesion. We describe a basis for determining the probability with which the latter class of mutations occurs based on the mutant fraction in the progeny and determine an average probability of 0.6 mutations/replication/mutagenic site for those EMS-modified sites which are mutagenic for G6PDH activity in CHO cells.