Production of erythropoietin in vitro: A review

Summary The in vitro production of the important regulatory of erythropoiesis, erythropoietin (Epo), is reviewed. It is concluded that it is possible to produce almost routinely small quantities of Epo in tissue culture. Although such procedures offer the potential to provide large quantities of the hormone for clinical use, the optimum culture conditions and mechanisms for triggering Epo production have yet to be resolved. This work was supported by Grants No. 74444 from The John A. Hartford Foundation, and HL 10567 from the National Institutes of Health.     

Formation of junctions and cell sorting in aggregates of chick and mouse cells

The frequency of desmosome formation was examined in aggregates of old cells, which form many junctions, combined with young cells, which form few. Cells of chick corneal epithelium and mouse epidermis, which can be distinguished morphologically, were combined. Desmosomes between these cell types are stable. Further, young cells make more desmosomes than they otherwise would on those surfaces adjoining old cells. Desmosomes increase in number in aggregates while cell sorting is occurring. Cells consistently sort, with those which form most desmosomes lying internally. Gap junctions and intermediate junctions are also present, but are uncommon. A carbohydrate cell-surface coat has regenerated by the time desmosome formation starts. The possible relation of desmosome formation to cell sorting is discussed.     

Biosynthesis of cat hemoglobins A and B: Amino terminal acetylation of the β chain of HbB

Acetylation of the amino terminal serine of the β chains of cat HbB occurs during synthesis of hemoglobin in a mRNA dependent rabbit reticulocyte lysate protein synthesizing system in the presence of acetyl-CoA and cat reticulocyte mRNA. Both of the major cat hemoglobins, the nonacetylated HbA and acetylated HbB, are synthesized efficiently in the rabbit lysate system. The acetylation of HbB-β chains occurs during the biosynthesis of these proteins. Radioautography of tryptic peptide maps reveals that acetylation occurs specifically at the amino terminal serine of HbB-β globin, and not on HbA-β globin or on the α chain common to both hemoglobins A and B. Because of the similarity of the structures of HbA-β and HbB-β globin, it is suggested that the amino terminal residue determines whether the peptide chain is recognized for acetylation by a ribosomal acetyltransferase.     

Nutritional and karyotypic characterization of a haploid cell culture ofDaucus carota

Summary The purpose of this study was to optimize growth conditions for a strain of haploid carrot callus and to follow its karyotypic changes in a long span of time. The strain has been maintained in liquid suspension since September 1977. It has remained predominantly haploid in its karyotype since that time. The original explant was initiated and subsequently subcultured in Gamborg's B5 medium. The components of the B5 medium were omitted one at a time and sequentially added back to determine their minimum, optimum, and maximum nontoxic concentrations. These changes were made in the original formula: the addition of an organic buffering agent and an increase in the iron and other micronutrient concentrations. Using this slightly modified B5 medium, we assessed the effect on growth by single additions of amino acids, different carbon sources, growth regulators, and vitamins. No improvement in plating efficiency resulted from addition of any of these compounds. We conclude that there are factors limiting the plating efficiency of the haploid cells other than these tested, or that single additions will not make a discernible difference, or that growth promoting factors cannot be exogenously supplemented to cultured cells.     

Efficient protoplast isolation from fungi using commercial enzymes

Several commercial polysaccharases have been compared for their ability to liberate protoplasts from fungi. These enzymes were found to contain side activities capable of hydrolysing fungal cell walls. Protoplasts have been commonly isolated from fungi using enzyme systems prepared by workers in their own laboratories. However, these procedures are time consuming and considerable variation may be found between different batches of enzyme. The present study shows that high yields of protoplasts can be prepared from a variety of fungi using relatively cheap commercial enzymes. The yields obtained were normally as good as or better than those previously produced.     

Social interactions between adult male and infant rhesus monkeys in Nepal

In 1,506 hours of field observations on free-ranging rhesus monkeys in Kathmandu Valley, Nepal, in 1974 and 1975 18 cases of favorable social interactions between adult males and infants were observed. Eleven of these were brief encounters of play or grooming; seven were more extended cases of male care. One of the latter was a complete adoption of a neonatal orphan by a dominant male. This adoption was possessive and restrictive and it resulted in the death of the infant by starvation within three days. A similar adoption involving the same male occurred in 1976 and it also resulted in the death of the infant. Most of the favorable male-infant interactions occurred during the winter and spring when the infants were 6 to 12 months of age. These favorable social interactions involved eight males in six different troops, out of a total of about 48 males in 12 troops in our study population of approximately 600 monkeys. These observations are discussed in light of current sociobiological theories.     

Steroid estrogen conjugates in hens' urine II. identifications of some minor conversion products of intramuscularly injected [4-14c]estrone

[4-¹⁴C]Estrone was injected intramuscularly into two mature laying Rhode Island Red hens. Radioactive steroids and steroid conjugates recovered from the urine on Amberlite XAD-2 columns were fractionated on columns (100 cm) of DEAE-Sephadex A-25 by NaCl gradients. The presences of the following were confirmed, the figures in brackets indicating average proportions as per cent of total radioactivity recovered after Sephadex column chromatography: -the 3-β-glucuronides of estrone (10. 9) and of estradiol-17α plus estradiol-17β(9.8); the 17-β-glucuronides of estradiol-17α plus estradiol-17β (2.1); the 3-sulfates of estrone (14. 5) and of estradiol-17α plus estradiol-17β (27. 4); and the disulfates of estradiol-17α plus estradiol-17β (2. 3). The following additional conjugates were identified:-a β-glucuronide of 16-epiestriol (0.2) and a β-glucuronide of 16-ketoestradiol-17β (0. 2); the 3-sulfates of 16-epiestriol (1. 4), of 17-epiestriol (0. 9), of 16, 17-epiestriol (0. 7), of 16-keto-estradiol-17β (1. 1), and of 2-methoxyestrone (0. 7). Some evidence was obtained for the presence of 16, 17-epoxy-estratrienol-3-sulfate (1.9).     

Associations of like and unlike polysaccharides: Mechanism and specificity in galactomannans,interacting bacterial polysaccharides,and related systems

Chiroptical, rheological, and n.m.r.-relaxation evidence is presented, to identify interactions of two types between different polysaccharides: (1) mutual exclusion of incompatible molecules, with consequent increase in the effective concentration of both; and (2) energetically favourable association of structurally and sterically regular chain-segments. β-1,4-linked plant polysaccharides interact by association of unsubstituted backbone regions, either with like chians, or with sterically compatible, unlike molecules. Extracellular polysaccharides (xanthans) of Xanthomonas plant pathogens maintain their ordered native conformation in solution, and this accounts for their industrially valuable, rheological peculiarities. These materials bind strongly to the plant glycans. Random-coil bacterial gums show no such interactions, although dextran enhances autogelation of galactomannans by exclusion. Extracellular polysaccharides from Arthrobacter species also have ordered native conformations in solution, but do not share the specific interactions of xanthan. Native xanthan shows marked specificity in its interactions with plant glycans, indicating a possible biological role in host-pathogen recognition.