Insect Salivary Glands Research Articles

Serotonin transport by cultured bovine aortic endothelium.

Endothelial cells isolated from bovine aortas without prior treatment with enzymes were cultured in RPMI 1640 medium containing 17% fetal calf serum and antibiotics. The endothelial cells at confluency (7 days) were similar to endothelium in situ or to freshly isolated endothelial cells from blood vessels as seen by light, scanning, and electron microscopy. Cultured and freshly isolated indothelial cells exposed to labeled serotonin, even in the presence of iproniazid (5 x 10-4M), took up approximately 125 and 250 pmoles 14C-serotonin/mg protein, respectively, in 3 hours. Imipramine (10-4M) reduced uptake for both cell groups. Cold (4 degrees C) and metabolic inhibitors sharply reduced serotonin uptake by both freshly isolated and cultured endothelial cells. Ouabain (10-5M) almost completely blocked serotonin transport. Six analogues of serotonin at concentrations ten times above experimental serotonin concentrations did not affect serotonin transport in the cultured endothelial cells but did reduce it in the freshly isolated endothelial cells by 50%. The data on transport suggest that serotonin uptake is not unique to pulmonary endothelium, as has been suggested previously. In addition, using cultured indothelial cells to study serotonin transport is compatible with using other serotonin model systems such as platelets, lung, or brain. Lastly, serotonin uptake by endothelial cells may involve an active transport mechanism similar to that described for the pulmonary circulation, platelets, and insect salivary glands.

Chromosome products in Chironomus tentans salivary gland cells.

The messenger RNA of cells with polytene chromosomes deserves special attention in view of possibilities of tracing it to defined chromosomal loci and relating it to heterogeneous chromosomal RNA of defined origin. The differentiated state of such cells, to which certain insect salivary gland cells belong, is reflected at the chromosomal level in a pattern of special structural modifications, so-called “puffs.” Puffs are loci of RNA synthesis and likely to be responsible for the production of messenger RNA. Different tissues and developmental phases are characterized by specific patterns of puffs, some being common to several tissues, others being tissue-specific, like the Balbiani rings of the chironomids (Beermann, 1952). The relation between puff activities and the population of messengers is, however, little known. A special enigma is what precursor role the puff RNA, with apparent high molecular weights, has to messenger RNA. This paper will deal with questions of this kind.

Role of calcium and adenosine-3':5'-cyclic monophosphate in controlling fly salivary gland secretion.

The action of 5-hydroxytryptamine (5-HT) on an insect salivary gland was associated with a rise in adenosine-3':5'-cyclic monophosphate (cAMP) concentration and an increase in calcium uptake. An increase in secretion induced either by 5-HT or exogenous cAMP required extracellular calcium. Both 5-HT and exogenous cAMP increased (45)Ca efflux from previously labeled glands, but only 5-HT caused an increase in calcium uptake. The transepithelial potential in this tissue became more negative after addition of 5-HT, but more positive after addition of cAMP. 5-HT and cAMP induced a more negative potential when calcium was removed from the medium. It was concluded that both calcium and cAMP serve as intracellular messengers when 5-HT acts upon fly salivary gland.

Carbohydrate-free media for Crithidia.

SYNOPSIS. The insect trypanosomatid Crithidia fasciculata grew well at pH 3.8–6.3 in defined carbohydrate‐free media containing arginine (an essential amino acid) + proline + glutamic acid as substrates; glycerol was effective by itself. Precipitation of hemin in the acid media did not hinder growth. Further addition of succinic acid permitted growth matching that with carbohydrate. At pH 6.9–7.5 growth in this medium without carbohydrate with the aforementioned non‐fermentable substrates was slight; added carbohydrate (as sucrose or sorbitol) permitted good growth. Utilization of non‐carbohydrate substrates may contribute to Crithidia's ability (and presumably to that of pathogenic trypanosomatids as well) to multiply in the insect gut and to the ability of some Trypanosoma species to multiply in the insect hemocoel and salivary gland.

Structure of the Secretory Portion of Calliphora Salivary Glands

There has been much interest in the morphogenesis of the protein secretions of insect salivary glands. However, little is known about how the watery component of the saliva is produced. We have studied this aspect of secretion in Calliphora erythrocephala, an insect which apparently produces only one salivary enzyme, amylase. In vitro preparations of the abdominal portions of the paired salivary glands of this insect secrete fluid slowly. Addition of 5-hydroxytryptamine (1 x 10-9 M) to the bathing medium causes a 60-fold increase in the secretion rate. The secreted fluid is high in K and low in Na compared to the bathing medium.

Insect salivary glands: stimulation of fluid secretion by 5-hydroxytryptamine and adenosine-3',5'-monophosphate.

Low concentrations (10(-9)M) of 5-hydroxytryptamine increase the rate of fluid secretion by isolated salivary glands of adult Calliphora. 5-Hydroxytry ptamine is present in Calliphora brain. Adenosine-3',5'-monophosphate (cyclic AMP) also stimulates fluid secretion and may be involved in the mode of action of 5-hydroxytryptamine.

CULTURE OF INSECT SALIVARY GLANDS IN A CHEMICALLY DEFINED MEDIUM.

A method for culturing the salivary glands of Sciara coprophila in a chemically defined medium has been developed. During a 24-hour period, the polytene chromosomes from six larval stages undergo normal developmental mental changes, including puff formation, puff condensation, and DNA synthesis.

DIE ROLLE DER SPEICHELSEKRETE IM WECHSELVERHÄLTNIS ZWISCHEN TIER UND NAHRUNGSPFLANZE BEI HOMOPTEREN UND HETEROPTEREN

Im Speichel der Rhynchoten gibt es verschiedene Verdauungsenzyme, die eine weitgehende Anpassung hinsichtlich der Art der Nahrung aufweisen und bei der Verdauung wichtig sind. Zugleich gibt es im Rhynchotenspeichel auch Pflanzenwuchs hemmende Stoffe, Auxine und Viren, die alle Krankheitszustände bei den Nahrungspflanzen verursachen welche ihrerseits die Lebensbedingungen der Schädlinge fördern.SummaryThe above article is a short survey of the relation between the salivary secretions of the Hemiptera and their host plants.In analyses of the composition secretions in the salivary glands of phytophagous Homoptera and Heteroptera, the most extensive work has been done on the digestive enzymes. Proteases, amylases, saccharase, maltase, pectinase and lipase have been detected, but most commonly only 2–3 of these occurs in any one species. An adaptation of the enzyme complement to the diet is evident and in this respect the feeding site used by the insect is especially decisive to the enzyme composition of the saliva. Proteases and amylases occur in the saliva of mesophyll feeders, but are absent in phloem feeders, for which they are useless because, from the insect's point of view, the food is already digested. The adaptation of the salivary enzymes to the nature of the food seems to be largely inherited, for a diet containing nothing but sucrose does not induce adaptive changes in the enzyme content of the salivary glands. By contrast, papain seems to be transferred from a synthetic food to the salivary glands.The disease symptoms caused in plants by the salivary toxins of Homoptera and Heteroptera have many similarities to those caused by abnormal amounts of growth hormones. Indole‐tri‐acetic acid has been detected in extracts of crushed aphids and leafhoppers, although no growth stimulating hormones have been detected in salivary glands dissected from several heteropterous bugs and one aphid. On the contrary, substances inhibiting plant growth exist in the salivary glands of many Heteroptera and in at least one aphid. In some experiments with a heteropterous bug, indole‐tri‐acetic was observed to have been transferred from a synthetic diet to the salivary glands. It seems possible that auxins, enzymes and other phytotoxic substances occurring in the salivary glands of insects may at last in some cases originate from the host plant and are not produced by the insect.The salivary enzymes without doubt play an important role in the digestion of the insects secreting them. They are important also in the differentation of Homoptera and Heteroptera to different modes of life. The auxins or auxin inhibitors, as wel as all phytotoxic substances in the salivary glands of Homoptera and Heteroptera are significant for these animals by changing the physiological state of the host plant in such a direction that its suitability as a source of food increases.