Androstenedione, a steroidal dietary supplement taken to enhance athletic performance, could affect serum and liver lipid metabolism, induce liver toxicity or alter inflammatory response depending on dose and duration of exposure. Pregnancy could further exaggerate these effects. To examine this, mature female rats were gavaged with 0, 5, 30 or 60 mg/kg/day androstenedione beginning two weeks prior to mating and continuing through gestation day 19. Non-pregnant female rats were gavaged over the same time frame with 0 or 60 mg/kg/day androstenedione. Serum was collected and livers were removed from dams on gestation day 20 and from non-pregnant rats after 5 weeks of treatment. Androstenedione had no effect on serum total cholesterol, triglycerides or HDL-cholesterol, but significantly decreased C-reactive protein in pregnant rats and prostaglandin E(2) in serum of both pregnant and non-pregnant rats. There were treatment related decreases in liver ATP and, to a lesser degree, caspase-3 and no change in alkaline phosphatase of pregnant female rats. Androstenedione decreased docosahexaenoic acid in both serum and liver phospholipids of pregnant female rats. In conclusion, oral androstenedione did not result in overt hepatotoxicity in pregnant female rats, but produced modest changes in lipid metabolism and may impair regeneration of injured hepatic cells or tissue.

The compositions of liquidus olivines and orthopyroxenes of natural specimens of spinifex- and quench-textured peridotitic komatiites from the Belingwe Greenstone Belt, Rhodesia have been determined for pressures between 10 and 40 kbars. In conjunction with the chemical variation exhibited by these peridotitic komatiites it is concluded that the more magnesian lavas cannot be derived by concentration of olivine phenocrysts, fractional crystallisation or equilibrium partial melting. The peridotitic komatiites could evolve by polybaric assimilation and complete melting of garnet lherzolite into an initial liquid containing about 24% MgO.

Mullen and Whitten1 have demonstrated a correlation between coat phenotype and gametic output in tetraparental chimaeras produced by ovum fusion. We report a parallel study of AKR←⇐CBA-T6T6 chimaeras extended to include the assessment of lymphocyte chimaerism in blood culture.

SUSCEPTIBILITY to the spontaneous development of tumours is strain-dependent in mice1. Genetic factors are undoubtedly involved. Mintz et al.2 used tetraparental chimaeras derived from ovum fusion to investigate the effect on tumour development of combinations of strains which differ in susceptibility I and reported that the incidence of specific tumours in chim-aeras is concordant with that of mice of the more susceptible strain. We have found, on the contrary, delayed onset or absence of lymphomas in a small group of AKR↔CBA-T6T6/H chimaeras3. The AKR strain is notable for the early onset and almost total incidence of thymic lyphoma4. We now report confirmatory observations on a larger number of animals.

Chromosome preparations can be obtained from the membranes of midterm mouse embryos allowing the embryos themselves to be preserved for other investigations. Whole implants are dissected from the gravid uterus and exposed to 2 × 10−7 M Colcemid in TC medium 199 for 1 hr at 20–25 C. The membranes are removed, placed in 1% Na3-citrate at the same temperature for 4–12 min depending on gestational age, fixed in 3–4 ml of a 3:1 ethanol-acetic acid mixture for 1 min to 3 hr and transferred to 0.5 ml aqueous 60% acetic acid for 4 min. Cells detach from the membranes into the acetic acid. Chromosome spreads are then obtained by drying the acetic acid on heated slides. The method can be modified for tail tips of newborn young. Embryos on the 8th to 18th day of gestation and 1- to 6-day-old mice are suitable. (On the 8th to 10th days, preparations are made from embryo and membranes combined.) Preparations ready for scoring can be obtained from foetal membranes in 90 min and from tail tips in 150 min.

SUMMARYIf heterozygotes for a reciprocal translocation are intercrossed, some of their viable balanced progeny result from the fusion of unbalanced gametes with complementary duplications and deficiencies of the translocated segments. Therefore, if one parent in such an intercross is homozygous for a genetic marker on one of the segments concerned, some homozygous offspring will be produced even if the other parent does not have the marker. The expected frequency of such exceptional offspring among live-born is one-sixth if the marker is on the distal (non-centromeric) side of the point of exchange and single chiasmata normally occur in each interstitial segment. Much lower frequencies are expected if the marker is on the centromeric side, since duplications and deficiencies of proximal segments occur only as a consequence of adjacent-2 disjunction, in which homologous centromeres proceed to the same pole. This is rarer than normal disjunction. Thus, by comparing the frequencies of offspring homozygous for markers on one or other side of the point of exchange, it is possible (i) to determine which marker is in the centromeric segment, (ii) to estimate the frequency of adjacent-2 disjunction, given information on the nature of meiotic configurations in the translocation concerned.By this method, it is shown that the frequency of adjacent-2 disjunction is similar in heterozygotes for mouse translocations(T5;18)26H, T(13; ?) 70HandT(14;17)264Ca, averaging 13%. Centromeres were located at theSdend of linkage group V (confirming previous findings), thefzend of XIII and the bg end of XIV.

After a brief review of previously published views, the flotation of anorthosite crust, the fractional crystallisation process in lunar seas and some aspects of genesis of mascons are specifically discussed in the light of experimental data and the petrogenetic scheme which they support.

Translocation frequencies were studied in mouse spermatocytes derived from X-irradiated spermatogonia. Over the range from 50–800 R the dose-response relationship did not differ significantly from linearity, in agreement with previous findings of Léonard and Deknudt. It seems probable that the initial dose-response curve has the expected square-law component but becomes destorted by secondary factors between irradiation and meiotic examination of cells. Observed translocation frequencies were little affected by increasing length of time (from 11–30 weeks) between irradiation and examination, except for a possible decline at the highest dose (800 R). No significant frequency differences were found between mated and solitary males, or between those given whole-body or part-body (gonadal) irradiation.

The hindquarters of two batches each of five young adult male mice were exposed to an acute dose of 1,200 R of 250-kV X-rays in two fractions of 600 R, separated by a period of eight weeks. Means of 41.2% and 32.6% spermatocytes with one or more multivalent configuration were found when the mice were killed 13 to 18 and 59 weeks, respectively, after the second dose. The multivalent configurations were attributed to reciprocal transloeations induced in spermatogonia. Other types of chromosomal abnormality were rare. 150 sons were tested for semi-sterility and subsequently examined cytologically. Five were found to be translocation heterozygotes. One other was cytologically normal but nevertheless exhibited semi-sterility and transmitted this character to some of its descendents. The frequencies of spermatocytes with various numbers and types of multivalents were used to estimate the proportions of sperm with normal, balanced translocated and unbalanced haploid genomes, and hence the expected frequencies of zygotes with abnormal karyo types. The expected frequency of semi-steriles (or translocation heterozygotes) in the progeny proved to be about twice as great as that observed in parallel genetic experiments (Lyon et al., 1964; Searle, 1964) and in the sons of the irradiated males. Expected dominant lethals were also about twice as frequent as observed by Lyon et al. Whatever assumptions are made regarding the distribution of chiasmata in the multivalents and their manner of disjunction, the observed frequencies of translocation heterozygotes or dominant lethals or both are much less than the expected frequencies. The evidence is considered to favour a selective process operating on diploid rather than haploid genomes but perhaps taking effect on the haploid spermatids or sperm.

Autosomal translocation and male sterility in Romney sheep: 209 B-group chromosomes, deleted short arm in: 97, 109 Bisatellitcd chromosome, extra, familial: 177 Breeding of Meriones shawi x M. libyeus hybrids: 35 Cell line, established, hyperdiploid, hematopoietic, with persistent minute marker chromosome: 332 Chimcrism

IF mice are heavily irradiated, injected intravenously with an appropriate suspension of haematopoietic cells and killed 1–2 weeks later, prominent nodules can be seen on the surface of the spleen1. Microscopically, the nodules are foci of intense cellular proliferation and are commonly termed colonies. The linear relationship between the numbers of cells injected and the numbers of colonies observed1 and the exponential reduction of numbers of colonies with increasing dose when irradiated cells are injected1,2 suggested that each colony could be a clone of cells derived from a single progenitor cell in the inoculum1. Becker et al.3 provided direct evidence of clonal origin by irradiating recipients before and after injection, then finding individual colonies in which most mitotic cells had the same uniquely abnormal karyotype. This result has been supported by other experiments using marker chromosomes4–6. We now offer evidence that a single cell from the donor may give rise to two, three or four colonies in the irradiated recipient.