Preliminary studies of the effects of bromocriptine on testicular regression and the spring moult in a seasonal breeder, the male blue fox (Alopex lagopus)

Bromocriptine administration in the form of slow-release injections to male blue foxes during March-May abolished the normal spring rise in plasma prolactin concentrations seen in May and June. The spring moult was prevented and the treated animals retained a winter coat of varied quality and maturity until the end of the study in August. Plasma testosterone concentrations fell normally from March until August. Testicular regression was, however, delayed, although there were individual variations in response. Estimation by DNA flow cytometry in early July of the relative numbers of haploid, diploid and tetraploid cells in the testis showed that, in the treated animals, 74-80% of the cells were haploid (maturing germinal cells), 4-6% tetraploid (mainly primary spermatocytes) and the rest diploid cells (somatic cells and the remaining germinal cell types). In the control males, however, no haploid cells were detected and the majority of cells were diploid (93-99%). At castration in August, histological examination revealed various stages of testicular regression in the treated and control animals.     

Glycolipid core structure switching from globo- to lacto- and ganglio-series during retinoic acid-induced differentiation of TERA-2-derived human embryonal carcinoma cells

We have analyzed the glycolipid markers of a recently cloned human embryonal carcinoma (EC) cell line, NTERA-2, which differentiates extensively into a variety of somatic cell types when exposed to retinoic acid. These tumor cells provide a model system that can be used to study the ontogeny of glycolipid diversity during human embryonic development. Glycolipid antigens were identified by cell surface immunofluorescence and thin-layer chromatography immunostaining using a comprehensive set of anticarbohydrate monoclonal antibodies. Undifferentiated NTERA-2 cells were found to express predominantly globo-series glycolipids, including Gb3, Gb5 (IV3GalGb4), globo-ganglioside (IV3NeuAc alpha 2----3GalGb4), globo-H (IV3Fuc alpha 1----2GalGb4), and globo-A (IV3GalNAc alpha 1----3[Fuc alpha 1----2]GalGb4). When NTERA-2 cells were induced to differentiate by culturing in the presence of 10(-5) M retinoic acid, a remarkable shift of cellular glycolipids from globo-series to lacto- and ganglio-series was observed: Globo-series structures declined, particularly during the period 7-20 days after first exposure to retinoic acid, while lacto-series structures, including fucosyl alpha 1----3 type 2 chain (Lex) and sialosyl type 2 chain, and ganglio-series structures, including GM3, GD3, 9-O-acetyl-GD3, GM2, GD2, and GT3, increased. The presence of globo-A and globo-H as the major ABH blood group antigens in undifferentiated NTERA-2 cells suggests that globo-series blood group antigens are embryonic antigens, synthesis of which switches to lacto-series during human development. Two-color immunofluorescence analysis indicated preferential expression of several ganglio- and lacto-series antigens on different subsets of differentiated cells and permitted the relationship of these subsets to the development of neurons in NTERA-2 cultures to be determined. The results suggest that glycosyltransferase, particularly those involved in controlling glycoconjugate core structure assembly, are key enzymes regulated during the differentiation of human EC cells and, by implication, during human embryogenesis.     

Acetate addition to an immobilized yeast column of ethanol production

Acetate, a by-product of ethanol fermentation by Saccharomyces cerevisiae, has been shown to inhibit cell growth if present in high concentrations. Consequently, acetate has been considered undesirable in systems where the production rate depends upon steady-state growth. Acetate, however, may be desirable in some systems since it increases the specific rate of ethanol production by increasing the maintenance requirements of yeast. In immobilized cell reactors using the crosslinking method, steady state is not achieved and cell overgrowth is a problem. This article presents the results of a study aimed at taking advantage of the use of acetate, both to reduce cell overgrowth and to increase productivity. Various concentrations of acetate were added to batch and plug flow systems, while monitoring the effects on cell growth and ethanol production. The productivity was increased by as much as 50% in an immobilized cell reactor (ICR), while cell growth was greatly reduced.     

Effects of inoculum size on ethanol inhibition modeling and other fermentation parameters

The effects of inoculum size on the kinetics of ethanol fermentation are not well defined in the literature. The purpose of this article is to examine the influence of the initial cell concentration on the modeling of ethanol inhibition. Experimental results show that increasing the inoculum level decreases the severity of ethanol inhibition. The effect of cell concentration can be related to the different inhibitory effects of autogeneously produced versus extracellularly added ethanol. On this basis, it is concluded that the extracellular ethanol concentration in the fermentation media is not the only variable to account for product inhibition modeling. Other fermentation parameters, such as yields and maintenance coefficients, are presented at different levels of initial cell concentration.     

Tissue susceptibility factors in cadmium carcinogenesis

Recently, in two separate studies we have observed cadmium (Cd)-induction of prostatic tumors (PT) in rats. Cd (sc or im) at doses nontoxic to the testes markedly increased PT formation (2.5 μmol/kg, sc, 8 PT/29 exposed, 28%; 30 μmol/kg, im, 11/26, 42%; control 14/127, 11%). The administration of zinc (Zn; 1 mmol/kg, sc, at ?6, 0 and +18 h) to prevent testicular toxicity and tumors from Cd (30 μmol/kg, sc, 0 h) also resulted in an elevated incidence of PT (8/27, 30%). The nature of the metal-binding proteins in the prostate has not been defined, although metallothionein (MT), a low M_r Cd-binding protein that confers tolerance to Cd, is deficient in other target tissues of Cd carcinogenesis, such as the rat testes. Using a technique that extracts MT from liver, a low-M_r Cd-binding protein was extracted from both ventral (VP) and dorsal prostate (DP) and isolated by gel filtration. In contrast to the two forms of rat MT, reverse phase HPLC of VP and DP extract eluted 1 and 5 forms, respectively. The amino acid compositions of the VP and DP proteins were quite distinct from MT, with much less cys than MT and the presence of residues not found in MT (leu, tyr, phe). Thus Cd-induction of PT appears to be dependent on functional testes and, as is the case with Cd-induced testicular formation, appears to be associated with a deficiency of MT.     

Quantitative determination of Ca2+-dependent Mg2+-ATPase from sarcoplasmic reticulum in muscle biopsies.

The possibility of quantifying the total concentration of Ca2+-dependent Mg2+-ATPase of sarcoplasmic reticulum was investigated by measurement of the Ca2+-dependent steady-state phosphorylation from [gamma-32P]ATP and the Ca2+-dependent 3-O-methylfluorescein phosphatase (3-O-MFPase) activity in crude muscle homogenates. The Ca2+-dependent phosphorylation at 0 degree C (mean +/- S.E.) was 40.0 +/- 2.5 (n = 6) and 6.2 +/- 0.7 (n = 4) nmol/g wet wt. in rat extensor digitorum longus (EDL) and soleus muscle, respectively (P less than 0.001). The Ca2+-dependent 3-O-MFPase activity at 37 degrees C was 1424 +/- 238 (n = 6) and 335 +/- 56 (n = 4) nmol/min per g wet wt. in rat EDL and soleus muscle, respectively (P less than 0.01). The molecular activity calculated from these measurements amounted to 35 +/- 5 min-1 (n = 6) and 55 +/- 10 min-1 (n = 4) for EDL and soleus muscle respectively. These values were not different from the molecular activity calculated for purified Ca2+-ATPase (36 min-1). The Ca2+-dependent 32P incorporation in soleus muscle decreased in the order mice greater than rats greater than guinea pigs. In EDL muscles from hypothyroid rats at a 30% reduction of the Ca2+-dependent phosphorylation was observed. The Ca2+-dependent phosphorylation in vastus lateralis muscle from three human subjects amounted to 4.5 +/- 0.8 nmol/g wet wt. It is concluded that measurement of the Ca2+-dependent phosphorylation allows rapid and reproducible quantification of the concentration of Ca2+-dependent Mg2+-ATPase of sarcoplasmic reticulum. Since only 20-60 mg of tissue is required for the measurements, the method can also be used for biopsies obtained in clinical studies.     

Fermentation parameters of Peptostreptococcus productus on gaseous substrates (CO,H2/CO2)

Intrinsic growth and substrate uptake parameters were obtained for Peptostreptococcus productus, strain U-1, using carbon monoxide as the limiting substrate. A modified Monod model with substrate inhibition was used for modeling. In addition, a product yield of 0.25 mol acetate/mol CO and a cell yield of 0.034 g cells/g CO were obtained. While CO was found to be the primary substrate, P. productus is able to produce acetate from CO₂ and H₂, although this substrate could not sustain growth. Yeast extract was found to also be a growth substrate. A yield of 0.017 g cell/g yeast extract and a product yield of 0.14 g acetate/g yeast extract were obtained. In the presence of acetate, the maximum specific CO uptake rate was increased by 40% compared to the maximum without acetate present. Cell replication was inhibited at acetate concentrations of 30 g/l. Methionine was found to be an essential nutrient for growth and CO uptake by P. productus. A minimum amount of a complex medium such as yeast extract (0.01%) is, however, required.     

Names and naming: Instances from the ORU-IGBO

Conclusion People have many names. But, changing one's name is no small thing. It can signify a major step in life or an embarrassing story, as in the last case.A person has a complex individual identity. His collective identity is clear from the moment he is conceived. He is one with a body of people, his kinsmen, who share one common ancestor and through him access to land and resources. The continuation of this group and its name is perpetuated through paternal descent.Kingroup membership ensures a person's place in life, his right to exist, eat, live and enjoy. But, who is he, apart from being a kinsman? Which kinsman is he? How are people going to interact with him? His individual identity will become clear through time. He is a re-incarnation of ancestor x. The circumstances of his birth were such. He behaves like this. He has these personal traits. This has happened to him. He has achieved that. There is no permanent role attached to an individual. He is neither bound to class nor caste. He is dynamic and changes constantly. His life is one of achievement, constant striving and upward mobility till death — when it all begins again. His name signals his state of being in time and existence.Sabine Jell-Bahlsen is an anthropologist and filmmaker.     

Fanconi's anaemia: correlation of genetic complementation group with psoralen/UVA response

Summary The correlation found by Moustacchi (1987) between cellular response to a crosslinking challenge and genetic heterogeneity in Fanconi's anaemia is confirmed for an earlier set of complementation groups (Zakrzewski and Sperling 1980). This allows the matching of the two independently established complementation groupings and better characterization of their DNA repair-related biochemical properties.