Cell culture of bivalves: tool for the study of the effects of environmental stressors.

Spontaneous beating cells can be isolated from the heart of the oyster (Crassostrea gigas) and cultured for more than two months. They form adherent contractile networks in culture conditions. They show muscarinic and beta-adrenergic reactivity thus showing that they are functional cardio-myocytes: Acetylcholine induced a dose dependent decrease in spontaneous beating rate via an increase in potassium conductance, this effect being blocked by atropine. Epinephrine induced a dramatic increase in calcium conductance which was blocked by high concentrations of propranolol but not by sotalol and reversed by verapamil. Tributyltin and cadmium induced a dose and time dependent decrease mainly in inward ionic conductances, leading to a decrease or even a total suppression of the beating rate. Present study indicates that this model could be used as a sensitive test to study the effects of some marine pollutants at the cellular level in molluscs.     

Plant growth environment effects on rapeseed microspore development and culture : a flow cytometric study

The influence of donor plant growth conditions on microspore embryogenesis in rapeseed (Brassica napus) was studied for plants grown at 23/18°C (16/8 hours) under continuous light, 23/18°C (16/8 hours) with a light/dark (16/8 hours) cycle, 15/12°C (16/8 hours) under continuous light and 15/12°C (16/8 hours) with a light/dark (16/8 hours) cycle. Significantly higher embryo yields were obtained from microspore cultures initiated from donor plants grown at 15/12°C instead of 23/18°C. Flow cytometric measurements of the microspores isolated from 2.5- to 5.0-millimeter buds showed that the microspores isolated from low-temperature-grown plants had significantly lower log 90-degree light scatter to forward angle light scatter and log 90-degree light scatter to time of flight ratios than those isolated from high-temperature-grown plants, suggesting that the former are more translucent than the latter. Thus, the effect of donor plant growth temperature on microspore embryogenesis may be mediated by a change in the physiology of the microspore cell, which results in the reduction of its cytoplasmic granularity and/or exine density.     

Psychological and hormonal features of smokers at risk to gain weight after smoking cessation--results of a multicenter study

Preclinical and clinical data suggest modulating effects of appetite-regulating hormones and stress perception on food intake. Nicotine intake also interferes with regulation of body weight. Especially following smoking cessation gaining weight is a common but only partially understood consequence. The aim of this study was to examine the interaction between smoking habits, the appetite regulating hormone leptin, negative affectivity, and stress vulnerability on eating behavior in a clinical case-control study under standardized conditions.In a large population-based study sample, we compared leptin and cortisol plasma concentrations (radioimmunoassay) between current tobacco smokers with high cognitive restraint and disinhibition in eating behavior and smokers scoring low in both categories as assessed with the Three Factor Eating Questionnaire (TFEQ; Stunkard & Messick, 1985). As a measure for smoking effects on the stress axis, the saliva cortisol concentrations were compared before and after nicotine smoking. Additionally, stress perception was assessed with the Perceived Stress Scale (PSS), symptoms of depression and anxiety with the Beck Depression Inventory (BDI) and the State Trait Anxiety Inventory (STAI).In smokers showing high cognitive restraint and disinhibition we found significantly higher leptin concentrations than in the group of smokers scoring low in both categories. Furthermore there was a significant group difference in saliva cortisol concentrations after nicotine intake. Smokers showing high cognitive restraint and disinhibition were also characterized by significantly higher scores in the STAI, the PSS and the BDI.Our results suggest that smokers with a pathological eating behavior show an impaired neuroendocrine regulation of appetite and are prone to experience higher levels of stress and negative affectivity. This interaction of behavioral and neuroendocrinological factors may constitute a high risk condition for gaining weight following smoking cessation.     

Seasonal and management effects on fertility of the sow: a descriptive study

This study was undertaken to determine management and seasonal effects on fertility in 1298 Finnish sow units over a 4-year period in 1992-1996. A multivariate analysis of the herd record data was undertaken to study the effect of various management factors on rebreeding rate. Factors found to have an effect were further subjected to time series plotting for seasonal effects. In addition, seasonal effects on the farrowing rate, age of gilts at first mating and littersize as well as the 3-week litterweight were studied. Year and month caused the most significant variation in the rebreeding rate. Moreover, geographical area, herd and way of breeding (mating vs. artificial insemination) were found to be significant determinants of rebreeding rate. Dry sows loosely housed were more likely to be rebred than sows housed in individual stalls. Sows receiving roughage feed (hay, straw) or bedding (straw) were less likely to require rebreeding. A significant seasonal fluctuation in farrowing rate was found with a nadir of 72.6% in August and a high of 80.9% in January. The average farrowing rate for the 4-year period was 77.7%. The age of gilts at first mating showed seasonal variation of 11 days (229.9 +/- 0.5 days in March and 241.4 +/- 0.5 days in November). In conclusion, this study indicates that group housing of dry sows increases the risk of rebreeding. In group housed sows, rebreeding more often occurs after an irregular oestrus-to-oestrus interval in summer-autumn whereas a not-in-pig seems to be a more common finding at late gestation in individually housed sows.     

Methanococcus vannielii: culture and effects of selenium and tungsten on growth.

The reisolation, culture, and method of preservation of the methane-producing organism Methanococcus vannielii are described. Growth of the organism on formate is markedly stimulated by selenium and tungsten.     

Immunoregulatory effects of transforming growth factor-beta in a prolonged period of culture.

It is well known that transforming growth factor-beta (TGF-beta) strikingly inhibits numerous immune functions in short-term cultures. In this study we investigated the effects of TGF-beta on the immune responses of murine spleen cells in a prolonged period of culture. The addition of exogenous TGF-beta (0.1 ng/ml) inhibited the proliferation of Con A- or LPS-stimulated spleen cells, polyclonal IgM and IgG antibody production, and NK cell activity during 4 days of the initial culture and subsequently enhanced their responses on Day 10. The augmented polyclonal IgM and IgG responses in murine spleen cells induced by LPS and TGF-beta on Day 10 were suppressed by the secondary addition of TGF-beta on Day 6. These results suggest that TGF-beta acts as an immunoregulator in prolonged period responses by immunoactivators.     

Fishing and fertility: a study of a Nova Scotia fishing village.

The relationship between fertility and occupation is compared for: 1) deep-sea fishermen who are away from home as long as 21 days at a time with short rests between; 2) in-shore fishermen who are away at sea most nights; and 3) plant workers in the locality, used as controls. Particular attention was given to the families of fishermen who had done the same job since marriage. The population was old, relatively speaking, due to outmigration of younger people. 73% of the wives were over 30 years of age. Deep-sea fishermen are younger and have higher incomes than in-shore men (42.1 years vs 49.7 and $3544 vs $2900). Among women 15-44 years of age mean number of children for deep-sea fishermen was 3.35; in-shore, 3.60; plant workers, 3.62. Among those whose husbands had held the same job since marriage the variation was greater: deep-sea, 2.54; in-shore, 3.46; plant workers, 3.35. Among women over 45-years-old whose husbands had held the same job since marriage the number of children was 2.61, 3.94, and 4.27, respectively. 33% of plant workers had more children than desired and 66.7% said they had as many as desired. However, 25.9% of in-shore fishermen and 50% of deep-sea fishermen had fewer than desired. Interval between births was similar for all occupational groups (23.5-26.7 months) but the wives of deep-sea fishermen terminated childbearing earlier. Contraception was used only by the younger women, usually coitus interruptus or rhythm. Sterilization may have been important but it was hard to find out whether the 15% of wives who reported operations which made further childbearing impossible intended sterilization. 35.7% of deep-sea fishermens' wives reported such operations, generally women with larger families.     

Coping with fertility in Israel: A case study of culture clash

The concepts of culture-bound belief systems and explanatory models focused on reproduction and contraception are applied to a case of a married Jewish woman seeking to interrupt an unwanted pregnancy. Discrepancies between the lay belief system held by the woman, and the clinical belief system of the medical mediators of contraception and abortion, have created a situation where none of the alternatives at the woman's disposal seems correct: the options available for preventing pregnancy are unacceptable or inefficient; having a child is also not acceptable; and termination of unwanted pregnancy by abortion is ethically and morally wrong. The "no-win" situation results from medical ethnocentrism and failure to interpret the context of meanings and norms within which health decisions are constructed.     

Cell growth and catecholase production for Polyporus versicolor in submerged culture.

Cell growth and catecholase production for Polyporus veriscolor (ATCC 12679) were studied in mechanically agitated submerged culture, as functions of temperature. The exponential-phase growth rate exhibited a maximum at 28 degrees C. Over the range of 20 degrees C to approximately 30 degrees C, both cell mass and enzyme yield factors were constant. At higher temperatures (30 to 40 degrees C) cell mass yield factor decreased and enzyme yield factor increased. Specific respiration rate of P. versicolor was determined. Thermal deactivation of catecholase was investigated between 30 and 50 degrees C, and deactivation rates were fit to an Arrhenius rate expression.     

Insect tissue culture systems: models for study of hormonal control of development

Summary The regulation of growth and development of insects is under endocrine control and involves both juvenile hormones and ecdysteroids. Neuropeptides are master regulators which control the secretion of these hormones. Most experiments in insect endocrinology have been conducted in vivo, but tissue culture methodology is playing an increasing role due to the great interest in simpler model systems for the study of complex processes that occur in vivo. The availability of appropriate media has allowed the culture of a variety of insect organs and cell lines of defined origin which have kept certain properties of the parent tissues. Tissue culture approaches have been useful for studying hormonal control of morphogenetic processes. Cell lines are particularly suited to the study of hormonally regulated mechanisms of macromolecular biosynthesis and gene expression. Thus, the value of in vitro analysis in studies of regulation of hormone production is now recognized. Results obtained from tissue culture allow more precise definition of the hormonal requirements of insect cells and tissues for growth and differentiation and might make possible the discovery of new growth regulators.     

Kinetic features of a white rat hepatocyte population under hormonal disbalance before and after partial hepatectomy

Bilateral adrenalectomy, followed in 4 days by a partial hepatectomy, was performed using white rats weighing as much as 120-140 g. Under hormonal disbalance caused by bilateral adrenalectomy, the number of polyploid (4c, 4c x 2, and 8c) hepatocytes significantly increased, compared to that in non-operated control rats. Six hours after a partial hepatectomy, the share of highly ploid hepatocytes falls, being accompanied by a 9-fold increase in mitotic index. It is supposed that under hormonal disbalance condition, a partial hepatectomy may induce "early" mitoses in hepatocytes blocked in G2-phase of the cell cycle.     

Cell culture adaptation of astrovirus involves a deletion.

Astroviruses have been adapted to culture by serial blind passage in primary human embryo cells. All viruses thus adapted possess a 45-nucleotide deletion relative to fecal viruses or isolates made in CaCo-2 cells; this deletion may be responsible for the change in host cell range.     

Cell culture from lizard skin: a tool for the study of epidermal differentiation

An in vitro system of isolated skin cells has been developed in order to address the understanding on the factors that control the shedding cycle and differentiation of lizard epidermis. The skin from the regenerating lizard tail has been separated in epidermis and dermis, cells have been dissociated, cultivated in vitro, and studied ultrastructurally after 1–30 days of culture condition. Dissociated keratinocytes after 12 days in culture show numerous cell elongations and contain bundles of keratin or sparse keratin filaments. These cells often contain one to three 0.5–3 μm large and dense “keratinaceous bodies”, an organelle representing tonofilament disassembling. Most keratinocytes have sparse tonofilaments in the cytoplasm and form shorter bundles of keratin in the cell periphery. The dissociated dermis mainly consists of mesenchymal cells containing sparse bundles of intermediate filaments. These cells proliferate and form multi-stratified layers and a dermal pellicle in about 2–3 weeks in vitro in our basic medium. Conversely, cultures of keratinocytes do not expand but eventually reduce to few viable cells within 2–3 weeks of in vitro condition. It is suggested that dermal cells sustain themselves through the production of growth factors but that epidermal cells requires specific growth factors still to be identified before setting-up an in vitro system that allows analyzing the control of the shedding cycle in lizards.     

Cell growth patterns and lens geometry: a quantitative study from three-dimensional reconstructions

The growth of the lens of the sea lamprey, Petromyzon marinus, was studied over the 5 years of larval development. Whole lenses (25) and Golgi-impregnated cells (393) were reconstructed with computer-assisted microscopy. Several cellular geometric parameters (length, width, curvature, surface, volume, shape) were correlated with the position of the cell's base on the lens capsular perimeter. Based on these correlations, the cells formed four groups that correspond to the central anterior, germinative, transitional and cortical fiber zones. A fifth zone, containing nuclear fiber cells, never stained. Lens growth is exponential during the 5 years. The anterior epithelium increases in size and in cell number by cell growth and division. The posterior mass increases in cell number by recruitment and increases in size by cell growth. A model is proposed to account for the size and shape of the lens based upon the coupling of anterior and posterior growth patterns. Four zonal boundaries are defined by changes in cell growth patterns. With growth, cells are subsumed into adjacent zones and zonal boundaries move away from the lens center. We find no support for the suggestion that cells migrate centrally.     

Neural cells in culture: models for the purification and the study of the effects of growth factors

Conclusion and Perspectives We have summarized several methodologies currently available for the detection and analysisof protein factors affecting neural cells. As more knowledge is gained concerning growthfactors and their influences on cells and as the demand for bioassays increases, methodologicalimprovements are likely to be aimed at 1) decreasing yet the assay time; 2) increasingsensitivity of the measurements of cell responses; 3) increasing the number of simultaneouscellular responses measurable. A new very promising technique involves the use of severalfluorochromes having different cellular localizations and the continuous measurement of theirevolution in living cells by fluorospectrophotometry.The cell-blot method can be expected to extend to fractions submitted to other forms ofchromatography (native electrophoresis, isoelectric focusing, agarose). Other modificationsmay allow the detection of antagonistic factors, by including a stimulatory factor in the blotculture medium and measuring the suppression of a cellular response by the blotted opposingactivity.     

Mouse fetal kidneys in serum-free organ culture: effects of epidermal growth factor and hydrocortisone.

1. The present study was undertaken to determine whether epidermal growth factor (EGF, 100 ng/ml) or hydrocortisone (HC, 10(-8)-10(-5) M) directly influence proliferation and differentiation of mouse fetal kidney maturing in serum-free organ culture. 2. Addition of EGF to the medium significantly stimulated DNA synthesis after 2 and 5 days of culture. Labelled nuclei were mainly localized in the mesenchymal tissue. Protein synthesis remained unchanged. Activities of three hydrolases, markers of brush border differentiation, were reduced. 3. Hydrocortisone (HC), at all concentrations used, significantly inhibited DNA synthesis. Labelled nuclei were distributed in various cell populations of both control and treated explants. Protein synthesis was stimulated by 10(-7) M after 5 days of culture. Hydrolase activities were slightly modified by HC treatment. 4. The present results indicate that EGF stimulates whereas HC decreases proliferation. Both factors have regulatory effects on brush border maturation. 5. Thus, this culture model is a valuable tool for the study of nephrogenesis.