Expression of globin genes in teratocarcinoma-Friend cell hybrids

We have used an isoelectric focusing technique to analyse the hemoglobins synthesized by cell hybrids isolated following the fusion of Friend erythroleukemia to embryonal carcinoma cells. Our results confirm that the embryonal carcinoma-derived alpha globin genes are expressed in cell hybrids. In addition, the extent to which the various alpha chains and beta chains are synthesized in these hybrids depends on both the genetic composition of the cell line and on the chemical nature of the agent used to induce hemoglobin synthesis.     

Differential Mitotic Stability of Yeast Disomes Derived from Triploid Meiosis

The frequencies of recovered disomy among the meiotic segregants of yeast (Saccharomyces cerevisiae) triploids were assessed under conditions in which all 17 yeast chromosomes were monitored simultaneously. The studies employed inbred triploids, in which all homologous centromeres were identical by descent, and single haploid testers carrying genetic markers for all 17 linkage groups. The principal results include: (1) Ascospores from triploid meiosis germinate at frequencies comparable to those from normal diploids, but most fail to produce visible colonies due to the growth-retarding effects of high multiple disomy. (2) The probability of disome formation during triploid meiosis is the same for all chromosomes; disomy for any given chromosome does not exclude simultaneous disomy for any other chromosome. (3) The 17 yeast chromosomes fall into three frequency classes in terms of disome recovery. The results support the idea that multiply disomic meiotic segregants of the triploid experience repeated, nonrandom, post-germination mitotic chromosome losses (N + 1 leads to N) and that the observed variations in individual disome recovery are wholly attributable to inherent differences in disome mitotic stability.     

Induced sex reversal in Tilapia nilotica (Cichlidae) with methyl testosterone

Gonadally undifferentiated Tilapia nilotica fry were fed with methyl testosterone at the dosage of 50 mg/kg of dry diet. The fry used in the investigation belonged to two age groups with a mean total length of 10 mm and 13.5 mm. Treatment lasted for a minimum of four weeks and a maximum of six weeks. 100% males were obtained in all the various groups under androgen treatment.     

Electron paramagnetic and electron nuclear double resonance of the hydrogen peroxide compound of cytochrome c peroxidase

We have collected electron paramagnetic resonance (EPR) and electron nuclear double resonance (ENDOR) spectra from the hydrogen peroxide compound of yeast cytochrome c peroxidase, termed ES, employing EPR microwave frequencies of 9.6 and 11.6 GHz. We have measured and analyzed the temperature dependence of the spin-lattice relaxation rate (1/T1) of the paramagnetic center of ES over the temperature range 1.9 to 4 K. In addition, an upper bound to exchange coupling between the ferryl heme and EPR-visible centers of ES has been calculated and expressions for the dipolar interaction between a ferryl heme and a free radical have been derived. These results all confirm that the EPR signal of ES is not associated with an aromatic amino acid radical, and in particular not with a tryptophanyl radical. This conclusion has led us to consider an explanation of the EPR signal in terms of a nucleophilically stabilized methionyl radical.     

Joint Segregation of Biochemical Loci in Salmonidae. II. Linkage Associations from a Hybridized Salvelinus Genome (S. NAMAYCUSHxS. FONTINALIS)

The results of more than 300 pairwise examinations of biochemical loci for joint segregation in brook trout (Salvelinus fontinalis) and in the hybridized genome of lake trout (S. namaycush) x brook trout are summarized. Nineteen loci have been assigned to the following eight linkage groupings on the basis of nonrandom assortment, including cases of both classical linkage and pseudolinkage: ODH with PMI with PGI-3, PGI-2 with SDH, ADA-1 with AGP-2, AAT-(1,2) with AGP-1 with MDH-1, MDH-3 with MDH-4, LDH-3 with LDH-4, IDH-3 with ME-2 and GUS with CPK-1. Pseudolinkage (an excess of nonparental progeny types) was observed only for male testcross parents. The results suggest that this phenomenon involves homeologous chromosome arms as evidenced by the de novo association of presumed duplicate loci in each case. Classical linkage has not been found for the five pairs of duplicate loci examined in Salvelinus, suggesting that not all of the eight metacentrics in the haploid complement involve fusions of homeologous chromosomes. Females consistently showed a greater degree of recombination.     

Natural chelators in sea water: Detoxification of Zn2+ by brown algal polyphenols

We have examined growth responses of several species of marine phytoplankton, cultured with and without heavy metal stress, to supplements of polymeric polyphenols from the brown algae Ascophyllum nodosum (L.) Le Jol. and Fucus vesiculosus L. In the absence of additional heavy metals. supplements of up to 4000 μg. 1 of polyphenols had a small effect on initial growth rates for three of these microalgae and had no effect on maximum cell densities for four species. One very common, heavy metal-sensitive diatom, Skeletonema costatum (Grev.) Cl., showed significantly increasing maximum cell density in the cultures, with increasing addition of polyphenols to the medium. The toxicity of Zn²⁺ (0.5–2.0 mg·1 ¹) to cultures of the diatom Phaeodactylum tricornutum Bohlin was relieved by supplements (100–200 μg·1 ¹) of the brown algal polyphenols. Exudation of these polyphenols from brown seaweeds may contribute to the natural chelating capacity of inshore sea water.     

In vitro translation of maize ADH: Evidence for the anaerobic induction of mRNA

Total cellular RNA from anaerobically stressed maize seedling roots was used to stimulate in vitro translation of authentic maize alcohol dehydrogenase (ADH) in a rabbit reticulocyte lysate system. Total products from such reactions were displayed on NEPHGE-SDS two-dimensional gels and the Adhl-specific translation products were identified by using RNA from sib seedlings segregating for Adhl charge and size variants. The application of a rapid RNA isolation procedure allowed the efficient isolation of biologically active RNAs from small amounts of seedling material. Maize ADHs translated in vitro are identical in size to in vivo ADH. Further, no ADH was detected in the products of an in vitro translation reaction stimulated by total RNA from aerobically grown seedlings. This suggests that induction of ADH protein by anaerobic stress is accomplished by production of Adh mRNA rather than activation of sequestered mRNA. The mRNAs for maize ADH1 and ADH2 are among a small class of mRNAs induced during anaerobiosis.Research was supported by NSF Grant PCM 76-11009. M.D.B. is supported by National Institute of Health Grant PHS 5 T32 GM07227-04. R.J.F. is a Predoctoral Trainee in Genetics supported by National Institute of Health Training Grants 82 and 7757 from the National Institute of General Medical Sciences.     

Reconstitution of acetylcholine receptor from Torpedo californica with highly purified phospholipids: Effect of α-tocopherol,phylloquinone, and other terpenoid quinones

Acetylcholine receptor from $\text{Torpedo californica}$ can be incorporated by the cholate dialysis procedure into liposomes prepared with crude soybean phospholipids (asolectin). Vesicles reconstituted with asolectin depleted of neutral lipids or with a mixture of pure phospholipids, are less active in catalyzing carbamylcholine-sensitive Na⁺ flux. Inclusion of α-tocopherol or certain quinones such as coenzyme Q₁₀ or vitamin K₁ during reconstitution yields vesicles with carbamylcholine-sensitive Na⁺ flux which, under optimal conditions, was considerably higher than that observed with vesicles reconstituted with crude phospholipid mixtures.     

Selective localization of lymphoblasts prepared from guinea pig intestinal lamina propria

The tissue localization patterns of radiolabeled dividing cells obtained from gut lamina propria (LP), mesenteric (MLN) and peripheral (PLN) lymph nodes, and Peyer's patches (PP) were studied in guinea pigs using an adoptive lymphocyte transfer method. Within 24 hr ¹²⁵I-deoxyuridine-labeled cells from donor LP and MLN, but not PLN, selectively localized in recipient gut and MLN. In contrast, donor PLN lymphoblasts returned to their sites of origin while labeled PP donor cells exhibited no specific tissue localization. These findings suggest that the gut LP, like the MLN, contains a population of cells which, unlike those in the PP and PLN, has the capacity to selectively localize in mucosal tissues. From this and other published work, we conclude that within the LP there is a population of cells at different stages of differentiation with a propensity to populate mucosae.