Ecdysteroids in vitro promote differentiation in the accessory glands of male mealworm beetles

Summary Physiological peak doses of 20-hydroxyecdysone were added to organ cultures of young pupal accessory glands of maleTenebrio molitor. During subsequent culture in vitro or in vivo, the glands accumulated adult-specific antigens. Control organ cultures showed no such antigen accumulation. In this system, ecdysteroid controls not only cell cycles but also differentiation.21 October 1986This research was supported in part by a National Institutes of Health Research Service Award F32 AM7515 (KAG) and NIH grants GM26140 and AI15662 (GMH). We thank Toshinobu Yaginuma for help in developing the transplantation technique.     

Changes in patterns of ecdysteroid secretion by the ring gland ofDrosophila in relation to the sterol composition of the diet

Summary Brain-ring glands fromDrosophila larvae reared on a defined diet containing campesterol (24-methyl-cholesterol) as the major sterol, secreted-in addition to ecdysone-a compound identified previously as a 24-methyl analogue, 20-deoxy-makisterone A. Using ergosterol or cholesterol as the sterol component of the diet, only ecdysone was detectable in cultures of brain-ring glands.     

Acetylcholine synthesis and its dependence on nervous activity

Summary The findings discussed in this paper mainly derived from studies on salivary glands, serving as model organs, indicate that the capacity to form the neurotransmitter acetylcholine, as judged by the activity of choline acetyltransferase, is influenced by the traffic of nerve impulses, as a long term effect. In the glands, choline acetyltransferase seems to be exclusively localized to the cholinergic nerves. In the postganglionic parasympathetic nerves of the glands, the activity of choline acetyltransferase decreases when the flow of secretory impulses in these nerves is abolished or reduced either by isolating the nerves from the central nervous system, surgically or pharmacologically, or by diminishing the reflex activation of the glands from the mouth. The opposite occurs when the reflex activation of the salivary glands is enhanced, i.e. the activity of choline acetyltransferase increases. Observations on various other organs are quoted in support of the view that the traffic of nerve impulses is of importance for the activity of the enzyme. An increase, in choline acetyltransferase activity also occurs in some salivary glands after sympathetic denervation. This puzzling observation is discussed in relation to impulse traffic. Increased nerve impulse traffic and collateral sprouting seem to be responsible for the rapid restitution of choline acetyltransferase activity from a low level in an organ partially deprived of its cholinergic nerve supply.     

Acetylcholine synthesis and its dependence on nervous activity.

The findings discussed in this paper mainly derived from studies on salivary glands, serving as model organs, indicate that the capacity to form the neurotransmitter acetylcholine, as judged by the activity of choline acetyltransferase, is influenced by the traffic of nerve impulses, as a long term effect. In the glands, choline acetyltransferase seems to be exclusively localized to the cholinergic nerves. In the postganglionic parasympathetic nerves of the glands, the activity of choline acetyltransferase decreases when the flow of secretory impulses in these nerves is abolished or reduced either by isolating the nerves from the central nervous system, surgically or pharmacologically, or by diminishing the reflex activation of the glands from the mouth. The opposite occurs when the reflex activation of the salivary glands is enhanced, i.e. the activity of choline acetyltransferase increases. Observations on various other organs are quoted in support of the view that the traffic of nerve impulses is of importance for the activity of the enzyme. An increase in choline acetyltransferase activity also occurs in some salivary glands after sympathetic denervation. This puzzling observation is discussed in relation to impulse traffic. Increased nerve impulse traffic and collateral sprouting seem to be responsible for the rapid restitution of choline acetyltransferase activity from a low level in an organ partially deprived of its cholinergic nerve supply.     

Response of neonatal mouse lung in organ culture to silica

Summary Short term organ cultures of lung fragments from neonatal mice maintain their normal architecture. Cultures exposed to silica flour in varying concentrations show effects resembling those seen in chronic silicosis produced by inoculation and inhalation methods.     

A biphasic effect of estradiol on serotonin metabolism in rat pineal organ cultures

Summary Physiological amounts of estradiol (1 nM) significantly increased serotonin, conversion to melatonin and 5-methoxytryptophol by rat pineal glands in organ culture whereas larger, pharmacological, doses (i.e. 1000 nM) impaired it significantly. The stimulatory but not the inhibitory effect of estradiol was blocked by the simultaneous addition of puromycin in the culture medium.This study was supported by grant No. 6638 from the Consejo Nacional de Investigaciones Cientificas y Técnicas (CONICET), Argentina.     

Biological effects of singlet delta oxygen on respiratory tract epithelium

Exposure of hamster tracheal organ cultures to gas phase singlet delta oxygen, O2, at atmospheric pressure produced significant alterations in the mucociliary epithelium resulting in changes in ciliary activity and cellular morphology.     

Inhibition of plasminogen activator production in organ cultures by cycloheximide

Summary The production of tissue plasminogen activator (TPA) in rat tongue organ cultures is strongly inhibited by low concentrations of the protein synthesis inhibitor cycloheximide. TPA production is fully resumed after the removal of cycloheximide from the culture medium.This study was supported by a USPHS grant (HE-05050) from the National Heart and Lung Institute.     

Promotion of epithelial keratinization by N-methyl-N'-nitro-N-nitrosoguanidine in rat forestomach in organ culture.

The effect of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) on epithelial differentiation of fetal rat forestomach was investigated in organ culture. When forestomach tissues removed from 16.5-day fetuses were treated with 5 microgram and 3 microgram of MNNG per ml for 1 h, epithelial keratinization was observed after 4 and 5 days, respectively, whereas it occurred after 6 days in control cultures. A clear dose-response relationship was found in the promotion of epithelial keratinization by MNNG.     

The assessment of tobacco smoke toxicity in organ culture. II. Ultrastructural studies on the immediate response of foetal rabbit tracheal epithelium to short-term exposures of whole smoke.

Foetal rabbit tracheal organ cultures were exposed under defined conditions to whole cigarette smoke and fixed immediately for electron microscopy. After an exposure to 4 or 8 puffs, epithelial intercellular spaces were enlarged, the apical portion of many cells bulged out into the lumen and many cilia were swollen. An exposure to 12 puffs produced a breakdown of the epithelium.     

Development of rhythmic melatonin synthesis in cultured pineal glands and pineal cells isolated from chick embryo

The chick pineal gland exhibits circadian rhythms in melatonin synthesis under in vivo and in vitro conditions. A daily rhythm of melatonin production was first detectable in pineal glands isolated from chick embryos at embryonic day 16 and incubated under a LD cycle. All pineal glands isolated from 17-day-old and older embryos were rhythmic while no gland isolated at embryonic day 14 and 15 exhibited a daily rhythm in melatonin synthesis. Melatonin production in static cultures of embryonic pineal cells was rhythmic over 48 h if the cells were kept under a LD cycle. When embryonic pineal cells were incubated in constant darkness the rhythm in melatonin production was damped within 48 h. These results suggest that chick pineal cells from embryonic day 16 onwards are photosensitive but that the endogenous component of the melatonin rhythm is not completely developed at that age. A soluble analogue of cAMP stimulated and norepinephrine inhibited melatonin synthesis in cultured embryonic pineal cells. These findings indicate that the stimulatory and inhibitory pathways controlling melatonin synthesis in the mature pineal gland are effective in pineal cells isolated from chick embryos at least 2 days before hatching.     

UV guided dendritic growth patterns and the networking of melanocytes

Whole skin organ cultures of vitiliginous, skin show that the marginal melanocytes are highly sensitive to a pulse of UV exposure (210–380 nm) during the G₂ phase of the cell cycle, as seen by prominent dendricity. Melanocytes are highly dendritic in the epidermis overlying rapidly growing tumors, as well as within proliferative lesions such as basal cell carcinomas and aggressive seborrheic keratosis. In the organ cultures the dendrites extend towards the source of UV, i.e. the surface, while the main body lies along the basement membrane. The epidermal melanocytes overlying tumors lie, almost vertically, dendrites aligned towards the underlying tumor on one side and the surface on the other. Within tumors dendritic elongation is guided by mitotic and PCNA positive (S-phase) tumor cells, which are a source of ultraweak UV emissions in the range of 210–330 nm. These observations indicate that ultraweak biophoton emissions from neighbouring cells can simulate environmental cues and contribute to the plasticity of networks such as the melanocytes or the visual pathways.     

Renin in mouse but not in rat submandibular glands

Renin was found in the submandibular glands of male Quackenbush mice in concentrations higher than has been reported for any tissue of any strain or species. However, no renin-like activity could e detected in glands from male and female Wistar rats using either pH 5.8 or 7.4 for assay and a radioimmunoassay specific for renin's reaction product, angiotensin I. Rabbit submandibular glands contained renin.     

Biosynthesis of macromolecules of the intercellular matrix in aorta organ culture. Influence of the age of the animal]

Rabbit aorta organ cultures were used as a model for the study of the modifications of the rate of biosynthesis of intercellular matrix macromolecules with age. Aortas of new born (100 g), young (400 g) and adult (2 kg) rabbits were maintained in culture for several weeks. 14C-lysine is incorporated in all the macromolecular fractions of the aortas, even in polymeric elastin. The change with age of the distribution of proteins of the aorta-explants in successive extracts obtained by a "chemical dissection" procedure and the decrease of their specific radioactivity wtih age enabled us to characterise biochemically the "aging program" of the arterial wall.     

Peroxisomes in the apocrine sweat glands of the human axilla and their putative role in pheromone production

The products of the human apocrine axillary glands contain volatile steroids which act as pheromones. The steroidal structure of these pheromones implies that the axillary glands should be able to synthesize cholesterol which is the essential precursor of these molecules. Since important steps in cholesterol synthesis are localized within peroxisomes, we investigated the occurrence and the putative role of peroxisomes in the axillary glands at protein and mRNA levels by immunocytochemistry, Western blotting, and RT-PCR. Numerous peroxisomes were localized in the cells of the apocrine glands by immunocytochemistry, and the presence of catalase was confirmed by Western blotting and RT-PCR. Additionally, RT-PCR revealed the presence of mRNAs of two peroxisome-associated enzymes of the cholesterol biosynthetic pathway, mevalonate kinase and farnesyl diphosphate synthase. The results suggest that the peroxisomes in the human apocrine axillary glands may play a pivotal role in the biosynthesis of pheromones.     

Biological effects of singlet delta oxygen on respiratory tract epithelium

Summary Exposure of hamster tracheal organ cultures to gas phase singlet delta oxygen,¹O₂, at atmospheric pressure produced significant alterations in the mucociliary epithelium resulting in changes in ciliary activity and cellular morphology.Acknowledgments. The authors acknowledge helpful conversations with Professor R.W. Murray of the University of Missouri (St. Louis). We would like to thank the National Institute of Environmental Health Sciences for supporting this work through Public Health Grant 1-RO1-ESO1-O1A1-PHTB.     

Renin in mouse but not in rat submandibular glands

Summary Renin was found in the submandibular glands of male Quackenbush mice in concentrations higher than has been reported for any tissue of any strain or species. However, no renin-like activity could be detected in glands from male and female Wistar rats using either pH 5.8 or 7.4 for assay and a radioimmunoassay specific for renin's reaction product, angiotensin I. Rabbit submandibular glands contained renin.We wish to express our sincere thanks to Dr E. Hackenthal for his suggestions. This study was supported by the National Heath and Medical Research Council of Australia.     

The contribution of extrapineal sites of melatonin synthesis to circulating melatonin levels in higher vertebrates

While the production of melatonin in higher vertebrates occurs in other organs and tissues besides the pineal, the contribution of extrapineal sites of melatonin synthesis such as the retina, the Harderian glands and the gut to circulating melatonin levels is still a matter of debate. The amount of melatonin found in the gastrointestinal tract is much higher than in any other organ including the pineal and the gut appears to make a significant contribution to circulating melatonin at least under certain conditions. The gut has been identified to be the major source of the elevated plasma concentrations of melatonin seen after tryptophan administration and of the changes of circulating melatonin level induced by the feeding regime. Whereas the circadian and circannual fluctuations of the concentration of melatonin in the blood seem to be triggered by changes of the photoenvironment and its effect of pineal melatonin formation, basal daytime melatonin levels and the extent of their elevation at nighttime appear to be additionally controlled by nutritional factors, such as the amount and the composition of ingested food and therefore availability of tryptophan as a rate-limiting precursor of melatonin formation by the enterochromaffin cells of the gastrointestinal tract.     

Amiloride impairs the cholinergic regulation of potassium permeability in the human sweat gland but not in the rat submandibular gland.

Potassium permeability was monitored in human sweat glands and rat submandibular glands. Acetylcholine increased permeability in both tissues and the responses consisted of transient, calcium-independent and sustained, calcium-dependent components. Amiloride, a drug which inhibits Na(+)-H+ countertransport, impaired the regulation of potassium permeability in sweat glands but not in the submandibular gland. It is suggested that the stimulus-permeability coupling process in the sweat gland may be sensitive to the lowering of internal pH.     

Amiloride impairs the cholinergic regulation of potassium permeability in the human sweat gland but not in the rat submandibular gland

Potassium permeability was monitored in human sweat glands and rat submandibular glands. Acetylcholine increased permeability in both tissues and the responses consisted of transient, calcium-independent and sustained, calcium-dependent components. Amiloride, a drug which inhibits Na⁺?H⁺ countertransport, impaired the regulation of potassium permeability in sweat glands but not in the submandibular gland. It is suggested that the stimulus-permeability coupling process in the sweat gland may be sensitive to the lowering of internal pH.