scholarly journals The Digestive Enzymes of the Onychophora (Peripatopsis spp.)

1936 ◽  
Vol 13 (3) ◽  
pp. 329-343
Author(s):  
NORMAN G. HEATLEY
Keyword(s):  
Salivary Glands ◽  
Digestive Enzymes ◽  
The Individual

1. An investigation has been made of the digestive enzymes of Peripatopsis spp. 2. The pH of the gut varies between 6.0 and 8.2; it is usually about 7.0. 3. The salivary glands elaborate amylase, glycogenase, protease and carboxypolypeptidase. 4. The gut digestive enzymes consist of invertase, maltase, lipase, esterase, amino- and carboxypolypeptidase and dipeptidase. Gelatin is also liquefied by the gut, but at pH 3.0 only. 5. The properties of some of the individual enzymes have been examined.

scholarly journals THE ORIENTATION OF DNA WITHIN 80-ANGSTROM CHROMATIN FIBERS

1972 ◽  
Vol 52 (3) ◽  
pp. 639-647 ◽  
Author(s):  
David B. Dusenbery ◽  
Robert B. Uretz
Keyword(s):  
Electron Microscope ◽  
Fluorescence Microscopy ◽  
Salivary Glands ◽  
Acridine Orange ◽  
Average Thickness ◽  
Polarized Fluorescence ◽  
Chromatin Fibers ◽  
The Individual ◽  
Dna Packing ◽  
Chironomus Thummi

Squashing salivary glands of Chironomus thummi larvae, Amblystoma tigrinum erythrocytes, or Spirostromum frequently results in stretched chromatin having highly oriented DNA as determined by polarized fluorescence microscopy of acridine orange-stained preparations. The examination of such material from C. thummi in the electron microscope indicates that the individual chromatin fibers have an average thickness of 80 A as is usually found in embedded and sectioned material. It is thus concluded that the DNA lies nearly parallel to the axis of these chromatin fibers. Detailed calculations of the polarization expected from various models of DNA packing are contained in an appendix.

The Morphology and Physiology of the Salivary Glands of Hemiptera-Heteroptera

1941 ◽  
Vol s2-83 (329) ◽  
pp. 91-139
Author(s):  
B. A. BAPTIST
Keyword(s):  
Salivary Glands ◽  
Digestive Enzymes ◽  
Fluid Secretion ◽  
Accessory Gland ◽  
Glandular Epithelium ◽  
Small Cells ◽  
Zymogen Granules ◽  
Accessory Glands ◽  
Blood Sucking ◽  
Axial Canal

The salivary glands of the Heteroptera consist of a pair of primarily bilobed principal glands and accessory glands which vary very greatly in form and structure in different families. The glands are usually supplied with tracheae, and the principal glands are invested by a nervous plexus which is supplied by a glandular nerve from the hypocerebral ganglion of the stomatogastric system. The principal salivary gland of Notonecta is characterized by the presence of large cells having zymogen granules and by the storage of fluid secretion in vacuoles. In contrast, most of the remaining Heteropteran salivary glands belong to the vesicular type, having a one-layered glandular epithelium made up of small cells which discharge their secretion into a large central storage cavity or axial canal. This type of gland lacks zymogen granules but has small dense masses of reserve material in the basal or outer parts of the cells. There is normally no difference in the structure of the glandular epithelium in the different lobes. The accessory glands are either in the form of a thin-walled bladder-like vesicle, or are tubular or duct-like; they seem to be purely a development of the primary conducting glandular system, and are thus homologous with the salivary reservoir of other orders. All the information obtained in this work is strongly against the idea that the various lobes of Hemipterous salivary glands produce widely different chemical substances, each with a special function. The results obtained by Fauré-Fremiet have not been confirmed. Except with blood-sucking forms digestive enzymes were always found in the glands, two enzymes being the maximum number found in any particular gland. The enzymes were found to be always related to the type of food consumed, and were those concerned with the digestion of that particular component of the food which was present in the greatest proportion. In no case was a cellulase found. An anti-coagulant principle was found to be present in the glands of blood-sucking forms. The accessory glands appear to produce only a watery secretion, enzymes being absent. The pH of the principal gland is generally slightly acid, while that of the accessory gland is neutral. Mitochondria and Golgi bodies typical of insect tissue are present in certain glands, but show no relation to the secretion granules, and thus do not appear to contribute to secretion synthesis. From a number of experiments it appears that the action of the digestive enzymes is not sufficiently rapid for external digestion to take place to any great extent. It seems, however, certain that quite an appreciable quantity of the injected saliva is imbibed again, and that the salivary digestion continues in the stomach, where the food taken in is first stored. The pH activity range of the enzymes is in general wide.

Differential development and emission ofTheileria parvasporozoites from the salivary gland ofRhipicephalus appendiculatus

Parasitology ◽  
1995 ◽  
Vol 111 (2) ◽  
pp. 153-160 ◽  
Author(s):  
M. K. Shaw ◽  
A. S. Young
Keyword(s):  
Salivary Gland ◽  
Salivary Glands ◽  
Rapid Development ◽  
Secretory Activity ◽  
Rhipicephalus Appendiculatus ◽  
Parasite Development ◽  
Mammalian Host ◽  
Free Access ◽  
Collecting Ducts ◽  
The Individual

SUMMARYThe initiation of feeding of infectedRhipicephalus appendiculatusadults induces the rapid development ofTheileria parvasporoblasts within the salivary gland acini leading to the production of numerous sporozoites which are inoculated into the mammalian host initiating infection. In this study the pattern of development, host cell specificity and emission ofT. parvasporozoites within the salivary glands of heavily infected, 4-day fed adultR. appendiculatusticks was examined. Infected acini were randomly distributed throughout the salivary gland. Sporozoite development within each gland was not synchronized and wide variation in the rate of parasite development, which correlated with the secretory activity of the individual acinus, was observed in all glands examined. Previous studies had shown thatT. parvadeveloped primarily in Type III ‘e’ cells. However, in heavily infected salivary glands sporogony and the emission of mature sporozoites also occurred in ‘c’ cells of Type II acini. Sporozoite emission from infected cells occurred by a process similar to apocrine secretion. The loss of the apical membrane of the infected cell allowed sporozoites free access to the lumen of the acinus and into the collecting ducts of the salivary gland. Sporozoite discharge was gradual since few parasites were found in the acinus valve or in the collecting ducts. Furthermore, the small size of the acinar valve aperature ensures that only small numbers of sporozoites can be released at any one time from an infected acinus.

Natura History an Prevention of Radiation Injury

2000 ◽  
Vol 14 (1) ◽  
pp. 57-61 ◽  
Author(s):  
A.C. O'Connell
Keyword(s):  
Salivary Gland ◽  
Salivary Glands ◽  
Radiation Damage ◽  
Tissue Injury ◽  
Gland Weight ◽  
Oral Dryness ◽  
History Of ◽  
Salivary Gland Hypofunction ◽  
The Individual ◽  
Therapeutic Radiation

Radiation therapy for cancers of the head and neck can irreversibly damage the salivary glands. Xerostomia (subjective oral dryness) develops within the first week of therapy and is progressive, with devastating effects on the quality of life of the individual. The xerostomia does not correlate with the degree of salivary gland hypofunction. The mechanism of tissue injury in humans is still unclear, but much progress has been made with animal models. This paper reviews the natural history of radiation damage to human salivary glands and highlights the inter-individual variations in the responses to and recovery from therapeutic radiation. The degree of salivary gland damage is correlated to the dose of radiation delivered and the volume of gland included in the field of radiation. The molecular mechanism of acute radiation damage is not fully understood; however, long-term salivary gland dysfunction is associated with both loss of gland weight and loss of acinar cells. Various strategies have been used to prevent or alleviate the problem of salivary gland hypofunction following therapeutic radiation. This paper reviews the progress made to date and the possibilities for future interventions to prevent radiation damage.

THE RELATIONSHIPS BETWEEN FOOD AND DIGESTIVE ENZYMES IN FIVE SPECIES OF ANTS (HYMENOPTERA: FORMICIDAE)

1967 ◽  
Vol 99 (4) ◽  
pp. 408-411 ◽  
Author(s):  
G. L. Ayre
Keyword(s):  
Salivary Glands ◽  
Digestive Enzymes ◽  
Feeding Habits

AbstractResults of the analyses for digestive enzymes in the glands and midguts of five species of ants showed that invertase is usually secreted by the maxillary glands, amylase by the salivary glands, and protease and lipase by the midgut. Lipase was found in the post-pharyngeal glands but observations indicate that it is not associated with the digestion of ingested food. Differences in the activity of the enzymes in different species tended to reflect the feeding habits of the ants.

ANATOMY, HISTOLOGY, AND SECRETIONS OF SALIVARY GLANDS OF THE LARGE MILKWEED BUG, ONCOPELTUS FASCIATUS (DALLAS) (HEMIPTERA: LYGAEIDAE)

1958 ◽  
Vol 36 (6) ◽  
pp. 961-968 ◽  
Author(s):  
Joan F. Bronskill ◽  
E. H. Salkeld ◽  
W. G. Friend
Keyword(s):  
Salivary Glands ◽  
Digestive Enzymes ◽  
Oncopeltus Fasciatus ◽  
Milkweed Bug ◽  
Accessory Glands

As in most Heteroptera, the salivary system of Oncopeltus fasciatus (Dallas) consists of a pair of trilobed principal glands and a pair of tubular accessory glands with associated ducts; the anatomy and histology are reported in detail. Tests for digestive enzymes demonstrated the presence of amylase, protease, invertase, and lipase. The various lobes of the salivary glands contain different digestive enzymes, a finding that is at variance with some published reports on allied Heteroptera.

Digestion in the Tsetse-Fly: A Study of Structure and Function

Parasitology ◽  
1929 ◽  
Vol 21 (3) ◽  
pp. 288-321 ◽  
Author(s):  
V. B. Wigglesworth
Keyword(s):  
Epithelial Cells ◽  
Salivary Glands ◽  
Digestive Enzymes ◽  
Anterior Segment ◽  
Posterior Segment ◽  
Tsetse Fly ◽  
Peritrophic Membrane ◽  
Middle Segment ◽  
Columnar Cells ◽  
Blood Pigment

The anatomy, histology and digestive enzymes of the mid-intestine of the tsetse-fly have been investigated, and an attempt has been made to determine the functions of the various parts and to observe the changes to which they are subject during the digestion of blood.Histologically the mid-gut of Glossina consists of three regions:(i) An anterior segment of small, pale-staining, irregularly columnar cells, which comprises about half the total length of the mid-gut. The zone of giantcells containing bacteroids, which is very limited in extent, lies at about the middle of this region.(ii) A middle segment of large, deeply staining cells, heaped together in the resting state, which is separated abruptly from the anterior segment.(iii) A posterior segment, arising by gradual transition from the middle segment, composed of regular columnar cells.After a meal the blood is concentrated by the removal of fluid in the anterior segment but it shows no other change in this region. The giant-cells are greatly flattened but they do not regularly discharge the bacteroids which they contain and there is no evidence that these organisms play any part in the digestion of blood. Their possible function has been discussed.During digestion the cells in the middle segment contain globules of secretion, and vacuolated buds of cytoplasm are set free and disintegrate in the lumen. The blood shows an abrupt change on reaching this region; it turns black where it is in contact with the epithelium and amorphous masses of altered blood pigment are deposited.In the posterior segment, the epithelial cells become greatly vacuolated later in digestion and are probably concerned chiefly in absorption.The distribution of digestive enzymes agrees with these histological observations. The salivary glands and proventriculus contain no digestive enzymes, and the anterior and posterior segments of the mid-gut also are practically inactive. But the middle segment produces a very active tryptase which agrees in its pH-activity curve and other properties with the tryptase of the cockroach. A peptidase also is present but, except for a very weak amylase, enzymes acting upon carbohydrates are absent. The contents of the mid-gut are always slightly acid (about pH 6·5) and the tryptase present is well adapted to work at this reaction.These findings have been contrasted with those in a non-blood-sucking muscid (Calliphora). Here the salivary glands secrete an active amylase and the mid-gut is rich in amylase, invertase and maltase, whereas the proteolytic enzymes are extremely weak.Some observations have been made upon the tracheal supply to the walls of the gut. The epithelial cells of the middle segment have been shown to contain a very rich supply of intracellular tracheoles. These are usually difficult to make out in the resting cells but after a large meal the surface of the cells is ruptured and blood pigment enters the tracheoles and may extend to the sub-epithelial tracheoles and tracheae or even to quite large tracheal trunks. As the epithelial cells are flattened by the pressure of the meal, this pigment is set free in the lumen in the form of dark rods of haematin, which often bear a superficial resemblance to bacteria. The pigment in the deeper tubes appears to be slowly absorbed later. Intracellular tracheoles similar to these are present also in the mid-gut of Calliphora.The proventriculus in Glossina is a complex and has always been a puzzling structure. It has been shown that it acts as a sphincter between the fore-gut and mid-gut and that it is responsible for the production of the peritrophic membrane. This membrane, which is composed of chitin but contains a small quantity of protein, is secreted in the form of a fluid by the ring of large epithelial cells at the base of the proventriculus. The fluid is pressed and condensed to form a uniform membrane by being drawn through the cleft between the wall of the proventriculus and the funnel-shaped invagination of the fore-gut.The function of the peritrophic membrane has been discussed and it has been shown that it is freely permeable to digestive enzymes and to haemoglobin.

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