Neuropeptides in the gastrointestinal canal of Necturus maculosus

Summary The presence and distribution of regulatory peptides in nerves and endocrine cells of the stomach, intestine and rectum of a urodele amphibian, the mudpuppy, Necturus maculosus, was studied immunohistochemically in sections or whole-mount preparations of the gut wall. The effect of the occurring peptides on gut motility was studied in isolated strip preparations of circular and longitudinal smooth muscle from different parts of the gut.Bombesin-, neurotensin-, substance P- and VIP-like immunoreactivity was present in abundant nerve fibres in the myenteric plexus of both stomach, intestine and rectum. Single fibres or bundles were present in the circular muscle layer and in a well-developed deep muscular plexus in the intestine and rectum. Immunoreactive nerve cells were found in the myenteric plexus of the stomach, intestine (neurotensin only) and rectum. Gastrin/CCK-like immunoreactivity was observed only in a few fibres in stomach and rectum.Endocrine cells containing bombesin-, met-enkephalin-, gastrin/CCK-, neurotensin-, somatostatin- or substance P- like immunoreactivity were present in the mucosa.The effect of bombesin was an inhibition of the rhythmic activity in circular muscle preparations and in longitudinal muscle from the rectum, while longitudinal muscle from the stomach usually responded with a weak increase in tonus. Neurotensin, like bombesin, was inhibitory on the spontaneous rhythmic activity of circular muscle throughout the gut, while the effect on longitudinal muscle was an increase in tonus. Met-enkephalin and substance P increased the tonus of all types of preparations, and often, in addition, initiated a rhythmic activity superimposed on this maintained tonus. VIP had a general inhibitory effect on the preparations, decreasing tonus and/or abolishing rhythmic activity.It is concluded that bombesin-, neurotensin-, substance P- and VIP-like peptides are present in nerves throughout the urodele gut and may have physiological functions in regulating the motility of the gut. The gastrin/CCK-like peptide present in nerves of the stomach and rectum may affect the function of these parts of the gut. The regulatory peptides present in endocrine cells may, perhaps with the exception of the somatostatin-like peptide, affect the motility humorally.     

Embryonic development and molting of the antennal coeloconic no pore- and double-walled wall pore sensilla in Locusta migratoria (Insecta,Orthopteroidea)

Summary The embryonic development of antennal coeloconic sensilla was studied at four stages between 132 and 252 h after oviposition in Locusta migratoria. Initially the anlagen of the sensilla consist of 2–4 sensory cells and 3 enveloping cells. Two additional cells contribute later to the formation of socket and pit. The dendritic outer segments of the sensory cells elongate before the trichogen process grows out (ecdysis type I) with exception of one sensory cell in anlagen of poreless (np) sensilla. Other differences between np and double-walled wall pore (dw wp) sensilla are not visible until at least about 220 h after oviposition. Molting, which was studied in four stages, follows ecdysis type I in both sensillum types. The fourth enveloping cell maintains its tight connection to the socket of the sensillum even after apolysis. Its apical portion is torn off and shed together with the old cuticle. The electron-dense material between the dendritic sheath and the cuticular wall of the peg in np sensilla, which is regarded important for stimulus transmission, is not deposited during retraction of the trichogen cell. The concentric walls and spoke channels characteristic of dw wp sensilla result from deposition of cuticular material around wedge-shaped projections of the trichogen cell. The typical trilaminar 15 nm cuticulin layer is produced only on the ridges of these sensilla. The first cuticular lining of the spoke channels is only 7 nm thick and of a different structure. A flocculent material surrounds the outgrowing trichogen process. It is continuous with the filling of the spoke channels and can thus be considered as component of the stimulus-transmitting material in the functioning intermolt dw wp sensilla.     

CO2 sensitive receptors on labial palps ofRhodogastria moths (Lepidoptera: Arctiidae): physiology,fine structure and central projection

Summary The tips of the labial palps ofRhodogastria possess a pit housing uniform sensilla (Fig. 1), histologically characterized by wall-pores and receptor cells with lamellated outer dendrites (Fig. 2). The receptor cell axons project to glomeruli in the deutocerebrum (cf. Fig. 3) which are not innervated by antennal receptors. From their histology as well as from their central projection these sense organs are identical with palpal pit organs of other Lepidoptera (Lee et al. 1985; Kent et al. 1986; Lee and Altner 1986).Physiologically, the palp-pit receptors respond uniformly; they are most excitable by stimulation with carbon dioxide (Fig. 6) while they exhibit relatively moderate responses to various odorants (Fig. 4). The responses to CO₂ (Fig. 7) show a steep dose-response characteristic. In ambient atmosphere (i.e., ca. 0.03% CO₂) the cells are in an excited condition already; the seeming spontaneous activity exhibited in air is decreased if the preparation is kept under N₂ or O₂ or CO₂-free air (Figs. 7, 10). There is hardly any adaptation of the responses to continuous or repeated stimulation (Fig. 8). Perhaps CO₂ sensitivity is correlated with sensilla characterized by both wall-pores and lamellated dendrites. Pilot tests indicate that CO₂ perception might be widespread in the Lepidoptera (cf. Fig. 12), but the biological significance remains obscure.     

Uptake and polar transport of indoleacetic acid in moss rhizoids

In the cucumber ( Cucumis sativus L. cv. Straight Eight) cotyledon expansion assay, cytokinin-stimulated ethylene production was separated from cytokinin-stimulated growth through the use of potassium and calcium salts. Low concentrations of KC1, which dramatically promoted growth induced by cytokinin, inhibited ethylene evolution, while CaCl₂ at a concentration that had no effect on growth, strongly promoted the cytokinin-induced ethylene evolution. In contrast to the growth response, stimulation of ethylene production was not directly related to the presence of potassium or calcium but to their relative concentrations. Concentrations of KCl and CaCl₂ which promoted ethylene evolution singly, strongly inhibited it when mixed together. Low rates of exogenous ethylene had no effect on the growth response. Both the growth and ethylene responses were found to be general cytokinin phenomena. Cotyledon respiration was promoted by KC1, CaCl₂ and cytokinin, but its stimulation was not correlated with either growth or ethylene production. In the presence of KClm cytokinin-induced respiration sharply lowered the content of certain sugars during the large growth response and followed KCl uptake. Analysis of KCl uptake showed that its growth promoting synergism with cytokinin was not due to osmotic effects.     

A chemiluminescent method for measurement of activated oxygen forms in biological fluids and homogenates

A chemiluminescent method for measuring the concentration of activated oxygen species (O₂² and H₂O₂) is described. Its main features are: high sensitivity (10^?9 M H₂O₂), its applicability to systems with high optical absorbance in the visible spectral region, a wide linear dynamic range, and the possibility for recording the kinetics of the processes, in which activated oxygen species are involved.     

Über das gleichzeitige Vorkommen von zweierlei Eiweißkörpern in den Zellkernen vonPseudolysimachion spicatum und einigen anderen Scrophulariaceen

Zusammenfassung Die Zellkerne vonPseudolysimachion spicatum, Veronica cymbalaria undV. gentianoides enthalten zweierlei Eiweißkörper von je nach dem Entwicklungszustand unterschiedlicher Konsistenz. Bis zum Höhepunkt ihrer Entwicklung liegen sie als anscheinend amorphe flüssige oder gelartige Gebilde vor. Später tritt — mit gewebespezifischen Unterschieden — Verfestigung und Kristallisation ein, und zwar bei beiden nicht gleichzeitig und z. T. auch nur beim großen. Beiderlei Körper unterscheiden sich deutlich in physikalischer und chemischer Hinsicht, außerdem in ihrer Entwicklungsgeschichte und Strukturveränderung. Sie fehlen in den Schließzellen, im Antherentapetum, in den Pollenmutterzellen, Pollenkörnern, im Embryosack, im Endosperm und im Embryo.Die Zellkerne in der Blattepidermis vonPenstemon barbatus enthalten ebenfalls zweierlei Eiweißkörper. Davon liegt einer als kugeliges Gebilde, der andere als Kristallstapel vor.

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Summary In the nuclei ofPseudolysimachion spicatum, Veronica cymbalaria, V. gentianoides there occur two different kinds of protein bodies. They clearly differ from one another in physical and chemical regard as well as in their ontogeny. At first they are amorphous, liquid or geluous. As a rule a consolidation or crystallization with differences according to the tissue takes place after the climax of the development, and that not at the same time within both bodies. In the stomata cells, pollen mother cells, in the embryo sac, in the endosperm, in the endothelium and in the embryo both bodies do not occur.The nuclei in the epidermis of the leaves ofPenstemon barbatus also contain two different kinds of protein bodies, one of them appearing as a round body, and the other one as a pile of crystal plates.