Elutriation of human keratinocytes and melanocytes fromin vitro cultured epithelium

Summary Human epidermal keratinocytes grown in culture and at different stages of differentiation are shown to be viably separated by elutriation. A specific fraction enriched in melanocytes was obtained. Elutriation of cells obtained fromin vitro cultured epithlium could prove useful in studies concerning the biochemistry and molecular markers of cells isolated from normal epithelium and from different pathologies.     

Polyamine Metabolism and Osmotic Stress : II. Improvement of Oat Protoplasts by an Inhibitor of Arginine Decarboxylase

We have attempted to improve the viability of cereal mesophyll protoplasts by pretreatment of leaves with dl-α-difluoromethylarginine (DFMA), a specific `suicide' inhibitor of the enzyme (arginine decarboxylase) responsible for their osmotically induced putrescine accumulation. Leaf pretreatment with DFMA before a 6 hour osmotic shock caused a 45% decrease of putrescine and a 2-fold increase of spermine titer. After 136 hours of osmotic stress, putrescine titer in DFMA-pretreated leaves increased by only 50%, but spermidine and spermine titers increased dramatically by 3.2- and 6-fold, respectively. These increases in higher polyamines could account for the reduced chlorophyll loss and enhanced ability of pretreated leaves to incorporate tritiated thymidine, uridine, and leucine into macromolecules. Pretreatment with DFMA significantly improved the overall viability of the protoplasts isolated from these leaves. The results support the view that the osmotically induced rise in putrescine and blockage of its conversion to higher polyamines may contribute to the lack of sustained cell division in cereal mesophyll protoplasts, although other undefined factors must also play a major role.     

Accuracy and direction of error in the sexing of the skeleton: implications for paleodemography

Determinations of sex by subjective assessment of the skulls from a skeletal series of known sex were compared to fully independent assessments based on pelves of the same specimens. Within-sex correlations of cranial and pelvic morphologies measured on an android-gynecoid scale were smaller than expected. Subjective assessment by means of the skull compared favorably to that of the linear discriminant functions of Giles and Elliot; however, the direction of error was similar for both procedures. Of course, estimations based on the pelves were generally superior to both in terms of frequency and overall bias of error. The bias of sex estimation for paleodemographic purposes is contingent upon completeness of skeletal remains.     

Glucocorticoids Potentiate the Prostaglandin E1-Mediated Cyclic AMP Formation by a Cultured Murine Neuroblastoma Clone

The effect of steroid hormones on the prostaglandin E1 (PGE1)-mediated cyclic AMP formation by murine neuroblastoma clone N1E-115 was studied. Dexamethasone at submicromolar concentrations and corticosterone at micromolar concentrations (steroids with glucocorticoid activity) were able to modify the PGE1-mediated response whereas testosterone, progesterone, and estradiol each at 10 microM had no effect. Glucocorticoids added to the culture medium of N1E-115 cells produced an increase in the maximal response to PGE1 only after long-term (greater than or equal to 4 h) incubation with the hormone. Inhibitors of protein and RNA synthesis blocked this effect of glucocorticoids. Basal activity of adenylate cyclase in treated cells was twofold higher than that in control cells, and this enzyme seemed to be the primary target for the hormone action, since the activity of 3':5'-cyclic AMP phosphodiesterase and the binding of [3H]PGE1 to its receptors were not altered by glucocorticoid treatment. Our results indicate that glucocorticoids modulate receptor-mediated responses in cells of neural origin through a mechanism that involves induction of protein synthesis.     

Rhodotorula nothofagi sp. nov., isolated from decayed wood in the evergreen rainy Valdivian forest of southern Chile

An unusual Rhodotorula isolated from decayed wood of Nothofagus obliqua (Mirb.) Blume is described and illustrated. This species differs from all accepted Rhodotorula species (1–7, 10) to warrant its establishment as a new species, Rhodotorula nothofagi sp. nov.Postgraduate student from the Instituto de Ecología y de Evolución, Universidad Austral de Chile, Valdivia.     

An improved method to isolate lichen algae by gel filtration

Photobiont cells of the lichen Evernia prunastri have completely been separated from their fungal partner by filtration through a bed of Sepharose 2B. Both mannitol and ribitol have been quantified by gas-liquid chromatography in the different steps of the isolation procedure. Absence of mannitol, which is exclusively produced by the mycobiont, has been used as the best probe to monitor isolation.     

Modulation of natural killer activity by thymosin alpha 1 and interferon

Summary A single injection of -interferon (-IFN) (30 000 units/mouse), a major biological modifier of natural killer (NK) cytolytic activity, strongly stimulated NK activity in normal mice, as expected, while the same treatment did not statistically alter the NK response in cyclophosphamide (CY)-suppressed animals.We investigated the possibility of thymosin ₁ cooperating with -IFN in boosting NK activity in CY-suppressed animals.The results show that treatment with thymosin ₁ (200 g/kg) for 4 days, followed by a single injection of -IFN 24 h before testing, strongly restored NK activity in CY-suppressed mice. Thymosin ₁ was, moreover, able to accelerate the recovery rate of NK activity in bone marrow reconstituted murine chimeras.Taken together the data support the concept that the synergic effect between thymosin ₁ and -IFN could be the result of effects on differentiation of the NK lineage at different levels.     

Action ofN-methyl-N′-nitro-N-nitrosoguanidine inRhizobium trifolii

Rhizobium trifolii was highly resistant to the lethal effect ofN-methyl-N-nitro-N-nitrosoguanidine (MNNG), but it was sensitive to the mutagenic action of this chemical. A concentration of 500g/ml yields a survival of between 1% and 10%, which allows us to obtain a higher number of mutants than lower concentrations that yield higher survival rates. Lethal damage produced by nitrosoguanidine was repaired, and repair is inhibited by acriflavine.     

Acrosomal reaction and early events at fertilization in Marthasterias glacialis (Echinodermata: Asteroidea)

When the spermatozoon of M glacialis contacts the mature oocyte jelly it adheres to it. Following this, there is a slight tumefaction of the acrosome, which is followed by the disruption of the apical acrosomal vesicle and cytoplasmic membranes. Acrosomal vesicle contents are liberated and spread along the outer surface of the oocyte jelly. Meanwhile, the acrosomal process begins to extend, penetrates all the jelly extension, then the vitelline layer, and finally contacts the cytoplasmic egg membrane. Nevertheless, the sperm cell continues lying at the outer border of the jelly. From the beginning of the acrosome reaction the dense and finely fibrillar subacrosomal material is connected, by some expansions, to the basal acrosomal vesicle membrane. Both nuclear and mitochondrial diameters have diminished.     

Purification of Tissue Forms (Amastigotes) of Trypanosoma cruzi by Immunoaffinity Chromatography1

A rapid and simple method for the purification of amastigotes of Trypanosoma cruzi from spleens of infected mice is described. A protein A-Scpharose 4B immunoadsorbent column bound with antisera to epimastigotes of T. cruzi was used to purify the tissue forms of this parasite. Host cells and debris are not retained, and parasites can be eluted in high yields and purity. Studies of surface glycoproteins and glycolipids of the purified amastigotes with 18 lectins of various specificities revealed the presence on the parasites of receptors for N-acetylglucosamine, N-acetylgalactosamine, D-galactose, and D-mannose binding lectins.