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B Tandler

Publications and source records attributed to B Tandler.

At least 37 records · Page 2Linked to original sources

Megamitochondria in the serous acinar cells of the submandibular gland of the neotropical fruit bat, Artibeus obscurus.

BACKGROUND: As part of a continuing investigation of the comparative ultrastructure of chiropteran salivary glands, we examined the submandibular glands of eight species of neotropical fruit bats in the genus Artibeus. We previously described secretory granules of unusual substructure in the seromucous demilunar cells of this organ in some species in this genus. In the present study, we turned our attention to the serous acinar cells in the same glands. METHODS: Specimens of eight species of Artibeus were collected in neotropical localities. Salivary glands were extirpated in the field and thin slices were fixed by immersion in triple aldehyde-DMSO or in modified half-strength Karnovsky's fixative. Tissues were further processed for electron microscopy by conventional means. RESULTS: In contrast to seromucous cells, which exhibit species-specific diversification in bats of this genus, the secretory apparatus and secretory granules in the serous acinar cells are highly conserved across all seven species. The single exception involves the mitochondria in one species. In this instance, some of the serous cell mitochondria in Artibeus obscurus are modified into megamitochondria. Such organelles usually have short, peripheral cristae; a laminar inclusion is present in the matrix compartment of every outsized organelle. Inclusions of this nature never are present in normal-size mitochondria in the serous cells. None of the megamitochondria were observed in the process of degeneration. CONCLUSIONS: The giant mitochondria in A. obscurus have a matrical structure that is radically different from that of the only other megamitochondria reported to occur in bat salivary glands. The factors that lead to variation in megamitochondrial substructure in different species, as well as the functional capacities of such giant organelles, are unknown.

Animals↗

Ultrastructure of the unusual accessory submandibular gland in the fringe-lipped bat, Trachops cirrhosus.

BACKGROUND: The phyllostomid fringe-lipped bat, Trachops cirrhosus, is sui generis (in a family of ca. 138 species) in that it subsists in part on tropical frogs. These amphibians frequently possess highly toxic integument. We examined the salivary glands of this bat to determine if these glands could be the source of protective factors that permit consumption of seemingly unsavory prey. The parotid and principal salivary glands of this bat are similar to homologous glands in other phyllostomids, but the accessory submandibular gland is unique. METHODS: The accessory submandibular glands of live-trapped T. cirrhosus were fixed and processed for transmission electron microscopy by conventional means. RESULTS: The accessory submandibular gland consists of follicles and ducts. The principal cells of the follicular walls have an abundance of rough endoplasmic reticulum (RER), free ribosomes, and extensive Golgi apparatuses. Typically, these cells have relatively few serous secretory granules. The ells contain collections of peculiar lipid droplets, and some of their mitochondria have dense crystalloids within expanded cristae. A layer of irregular, moderately dense bodies lies immediately subjacent to the luminal plasmalemma; it is not clear if these structures are endocytotic or exocytotic. Clusters of mucous cells, some of which have a single, hugely distended RER cisterna, are ensconced in the follicular walls; mucus from these cells reaches the lumen via intercellular canaliculi. Ducts progress from simple cuboidal to simple columnar epithelium. They lack basal striations, and their constituent cells contain relatively few mitochondria. Follicles and ducts have numerous myoepithelial cells at their periphery, and both are heavily innervated by hypolemmal nerve terminals. CONCLUSIONS: The unusual accessory submandibular gland in T. cirrhosus documents the extreme modifications in gland histology and in cell ultrastructure that have occurred in mammalian families. The cells composing the follicle walls and ducts bear little similarity to typical acinar or duct cells. Duplication of the submandibular gland in some bat lineages might be the key innovation underlying such plasticity. The heavy innervation of both follicles and ducts also implies that these structures are sensitive to and capable of responding to various inputs, perhaps including dietary factors.

Animals↗

Ultrastructure of the parotid salivary glands in seven species of fruit bats in the genus Artibeus.

BACKGROUND: In previous studies, we determined that the submandibular glands of five species of Neotropical fruit bats in the genus Artibeus had seromucous granules in their demilune cells with substructures that varied interspecifically in accordance with systematic relationships. Moreover, the striated ducts in these frugivores exhibited structural modifications that apparently are related to the consumption of a diet rich in potassium, but deficient in sodium. We now turn our attention to the parotid gland in a large number of species in this genus to determine if it follows the same structural pattern as does the submandibular gland. METHODS: Members of seven different species of Artibeus were live-trapped in various Neotropical locations. The parotid glands were extirpated from euthanized bats, fixed in the field, and prepared for electron microscopic examination by conventional means. The parotid glands in all seven species were virtually identical in morphology. The acinar cells (determined to be seromucous on the basis of ultrastructural criteria) contain large numbers of what appear to be vacuoles, but which are a type of secretory granule. These granules have an electron-lucent matrix and may contain one or several circular membranous profiles arranged either concentrically or in a random array. These granules appear to form by progressive dilatation of the termini of Golgi saccules, with the nascent granules finally severing their connection with the Golgi apparatus. Many of the internal membranous profiles are formed simply by invaginations of the limiting membrane of the granule; others may result from indentation of the limiting membrane by protrusions from adjacent granules; the source of multiple internal membranes in certain granules is unclear. The exocytosis of these granules results in the acinar and intercalated duct lumina being filled with an abundance of membranous material. Such extruded membranes are present in some striated ducts, but not in others, suggesting that they are degraded during passage through the duct system. The striated ducts are of conventional appearance, lacking the frondose processes that are prominent in the submandibular glands of Artibeus. CONCLUSIONS: The parotid gland in Artibeus shows none of the interspecific ultrastructural variability that characterizes the submandibular gland in bats of this genus. The seromucous acinar cells secrete granules that release phospholipids as well as glycoconjugates into the saliva. Based on the lack of frondose processes with their sodium-transporting portasomes, the striated ducts of the parotid gland are less concerned with electrolyte homeostasis than are those in the submandibular gland.

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Ultrastructure of the salivary glands in the midtongue of the common vampire bat, Desmodus rotundus.

BACKGROUND: All examined mammals have at least two sets of lingual salivary glands: von Ebner's glands and Weber's glands. A third set, the glands of Blandin and Nuhn, is present in the tongues of some but not all mammals. Vampire bats, Desmodus rotundus, are unusual in that they possess another set of lingual glands, these being in the midtongue region. METHODS: The anterior half of the tongue was extirpated from several adult vampire bats, dissected, and tissue blocks derived from the midregions of the body of the tongue prepared for transmission electron microscopy by conventional means. RESULTS: The midlingual glands are in the form of long, tubular secretory endpieces that are succeeded by ducts of simple morphology. In general, the secretory portions consist of two cell types, which may be intermingled in the same tubule or may form tubules that consist wholly of one cell type or the other. Seromucous cells usually have one or several rough endoplasmic reticulum cisternae that are hugely distended by a homogeneously dense material. Their granules have a bizonal substructure: one or several dense bands are embedded in a lighter matrix. Mucous cells are rather typical in structure, but their secretory product is different from run-of-the-mill mucous droplets. These droplets vary in density from cell to cell. In some cells, these droplets have a relatively light matrix; in other cells, the droplet is unusually dense, consisting mainly of a dark, structureless matrix with marginal lenticular lacunae of low density in which some short, irregular filaments are scattered. A rare finding is the presence of ciliated cells intermingled with secretory endpiece cells. The cilia are of conventional morphology. Secretory tubules are succeeded by ducts that resemble intercalated ducts; the epithelium of these ducts gradually increases in height to form a kind of excretory duct, without the intervention of striated ducts. As the ducts approach the lingual surface, the epithelium changes to stratified squamous. CONCLUSIONS: Saliva produced by the midlingual glands may be an aid in the reciprocal grooming behavior of vampire bats. Based on their morphology, the excurrent ducts may not modify the initial saliva elaborated by these glands and might act simply as pipelines by which the saliva reaches the mouth.

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A unique parotid gland in Hart's little fruit bat, Enchisthenes hartii.

BACKGROUND: Hart's little fruit bat, Enchisthenes hartii, is uncommon and, although it has been the subject of recent molecular genetic studies, is little known biologically. Because chiropteran salivary glands vary interspecifically in ways that reflect evolutionary history and ecology, we examined the parotid gland in E. hartii to ascertain the extent to which it resembles homologous glands in species to which this bat presumably is related. METHODS: The parotid glands were prepared for electron microscopic examination by conventional means. RESULTS: The parotid gland of E. hartii is structurally unique among all previously studied species of bats (> 230 species examined) and other mammals. In contrast to the same gland in other mammals, the parotid gland in E. hartii lacks secretory endpieces. In their place, there is a type of striated duct. Thus, in this species single secretory elements consist of (proceeding in the direction of salivary flow): striated duct--intercalated duct--and a conventionally located striated duct. The proximal ducts possess microvillus-lined intercellular canaliculi, whereas the walls of the distal ducts include occasional dark cells. Some small serous-like granules may be present in the intercalated duct cells. CONCLUSIONS: The function(s) and biological role of the unique parotid gland in E. hartii are unknown. Nevertheless, the presence of two sets of striated ducts provides two separate glandular components seemingly capable of electrolyte transport. This might be of adaptive significance in enabling this species to make use of tropical nutrient resources that otherwise would be unavailable. The uniqueness of its parotid glands lends support to the current hypothesis that E. hartii should be classified as a monotypic genus rather than as a species of Artibeus, whose members it resembles morphometrically.

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Ultrastructure of Weber's salivary glands of the root of the tongue in the rat.

BACKGROUND: The mammalian tongue encompasses several sizeable agglomerations of minor salivary glands. The ultrastructure of the various glands in the body of that organ has already been determined. In contrast, almost nothing is known of the structure of Weber's glands, a collection of salivary glands in the root of the tongue. METHODS: The entire tongue was extirpated from anesthetized adult male rats that had been perfused with fixative and specimens of tissue that included Weber's glands were dissected from the lingual root. These were prepared for electron microscopic examination by conventional means. RESULTS: Weber's glands in the rat are mixed glands, consisting of long mucous tubules that often are capped by serous demilunes. There appear to be no ducts per se, the mucous tubules increasing in caliber and approaching the crypts of the dorsal lingual surface while still retaining their mucous secretory character. As these ducts near the surface, their lining changes to stratified squamous epithelium. The mucous cells are cytologically similar to those in the sublingual glands of the same animal. Mucous droplets undergo vertical fusion to form centrally situated intracellular channels through which mucus is exocytosed, much in the same manner as goblet cells. The serous cells, which have all of the hallmarks of protein-secreting cells, probably empty their secretory granules via cellular extensions that directly reach the tubule lumen since there are no intercellular canaliculi between adjacent mucous cells. CONCLUSIONS: The mucus elaborated by Weber's glands undoubtedly aids in swallowing dry food. We postulate that the serous cells in these glands, as in the more anterior von Ebner's glands, might play a role in the mechanism of taste, especially where posteriorly situated, nonlingual taste buds are concerned.

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Iron overload in the rat pancreas following portacaval shunting and dietary iron supplementation.

Reproduction of pancreatic iron overload in an animal model has been difficult to achieve primarily because of the first-pass extraction of iron by the liver. We hypothesized that portacaval shunting would avoid this hepatic phenomenon and increase pancreatic iron deposition. An end-to-side portacaval shunt was surgically created in male Sprague-Dawley rats, and they were subsequently fed a carbonyl iron-supplemented diet for 17 weeks. This resulted in marked iron accumulation in the pancreas (1621 +/- 188 micrograms/g) compared to minimal deposition in sham-operated rats fed the same diet (138 +/- 53 micrograms/g). Iron deposition in the acinar and centroacinar cells was confirmed histologically by Gomori staining, as well as by ultrastructural examination. Iron overloading was associated with enhanced oxidative stress evidenced by a twofold increase in the levels of glutathione disulfide and thiobarbituric acid-reactive substances. Also, adducts of proteins with malondialdehyde and 4-hydroxynonenal were demonstrated in acinar and ductal cells. Other apparent consequences of iron overload were a 50% reduction in pancreatic amylase content and a decrease in pancreatic protein concentration. These hypotrophic changes were associated with a reduced mass of zymogen granules in the acinar cells noted histologically. Our results show that a combination of portacaval shunting and carbonyl iron feeding achieve pancreatic iron overload and support the role of oxidative stress in the pathogenesis of iron-induced damage in the pancreas.

Aldehydes↗

Myocardial ischemia decreases oxidative phosphorylation through cytochrome oxidase in subsarcolemmal mitochondria.

The effect of myocardial ischemia on mitochondrial oxidative phosphorylation was investigated using isolated, buffer-perfused rabbit hearts. After 45 min of global ischemia, oxidative phosphorylation was decreased only in the subsarcolemmal population of mitochondria with all substrates tested. The oxidation of N,N,N',N' tetramethyl p-phenylenediamine-ascorbate, an electron donor to cytochrome oxidase via cytochrome c, was decreased in subsarcolemmal mitochondria [ischemia (n = 6): 76 +/- 3 vs. control (n = 5): 105 +/- 6 nanoatoms O.min-1.mg-1, P < 0.01] but not in interfibrillar mitochondria. Only minor morphological changes were observed by electron microscopy in the isolated mitochondria after ischemia. Neither cytochrome oxidase activity measured under conditions for maximal activity nor the apparent Michaelis constant and maximum velocity values of the two cytochrome c binding sites were different in subsarcolemmal mitochondria isolated from ischemic and control hearts. The cytochrome c content was decreased in subsarcolemmal mitochondria after ischemia (ischemia: 0.111 +/- 0.013 vs. control: 0.156 +/- 0.007 nmol/mg protein, P < 0.05). Thus ischemia decreased the rate of oxidative phosphorylation through cytochrome oxidase selectively in intact subsarcolemmal mitochondria. Ischemic damage to the terminal segment of the electron transport chain involves a decrease in the content of cytochrome c, whereas the expressible catalytic activity of cytochrome oxidase remains unchanged.

Adenosine Diphosphate↗

Ultrastructure of the parotid gland in the common vampire bat, Desmodus rotundus, with special emphasis on oncocytes.

The parotid gland of the common vampire bat, Desmodus rotundus, is a pure seromucous gland. Typical acinar cells have a complement of secretory granules with a light matrix and one or several spherules and ancillary densities. These cells also contain mitochondria of conventional appearance. Mixed in with these acinar cells are cells that fulfil all of the ultrastructural criteria for identification as oncocytes. They contain enhanced numbers of mitochondria that frequently display peculiarities in the number and disposition of their cristae. The oncocyte mitochondria are closely packed and often are joined by periodic bridges. Most of the cells in the intercalated ducts are cytologically unremarkable; a few scattered duct cells have a single, grossly distended cisterna of rough endoplasmic reticulum that contains a homogeneous material of moderate density. The intercalated ducts are succeeded by ducts that lack the usual basal striations, but that consist of cells with numerous, small, dense granules. These secretory ducts probably are the homologues of striated ducts in parotid glands of other species. The structure of these ducts in the parotid gland in the vampire bat suggests that this gland does not play a homeostatic role in the regulation of electrolytes, a role that appears to be carried out in this bat in the submandibular glands, but that its major intralobular ducts contribute substantial quantities of organic material to the saliva.

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Cytomegalovirus in the parotid gland of a slow loris, Nyctecibus coucang.

Sporadic enlarged cells with both nuclear and cytoplasmic viruses were found in the intralobular ducts of the parotid salivary gland of an adult female slow loris; these ducts are homologous to striated ducts in the salivary glands of other primates. The duct cell nuclei contained reticular inclusions and virions in all stages of development. Cytoplasmic virions were, in almost every case, confined to vacuoles; only a very few were free in the cytosol. The viruses conformed in ultrastructure to that of cytomegaloviruses described in other species. This may be the first observation by electron microscopy of in situ cytomegaloviruses in the salivary glands of a nonhuman primate.

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Giant mitochondria induced in rat pancreatic exocrine cells by ethanol and iron.

BACKGROUND: Mitochondria are sensitive indicators of cellular pathology. Under certain circumstances, these organelles respond to cellular insult by a marked increase in size, resulting in the formation of giant mitochondria (megamitochondria). Ethanol has been implicated in the induction of giant mitochondria in rat hepatocytes. Since ethanol is reported to affect pancreatic mitochondria, we examined this organ for evidence of mitochondrial giantism in rats administered ethanol and a relatively small amount of supplementary iron. METHODS: Diets were administered via a chronically implanted gastrostomy catheter. Rats were segregated in four groups: 1) basic high-fat diet, 2) ethanol and a high fat diet, 3) carbonyl iron and a high-fat diet, and 4) ethanol and carbonyl iron combined with a high-fat diet. After the animals were on their respective diets for 16 weeks, specimens of pancreas were extirpated and processed for and examined by transmission electron microscopy. RESULTS: Mitochondria in rats on the basic high fat diet resemble those in untreated controls. With ethanol and a high-fat diet, some mitochondria in virtually every exocrine cell are profoundly altered. Such organelles, which are of normal size, have undergone rearrangement of their internal membranes, with three of four parallel cristae residing at one or both poles of spherical to ovate mitochondria. In rats receiving both ethanol and carbonyl iron, giant mitochondria are present in pancreatic exocrine cells. Except for their size, megamitochondria in many cases are virtual likenesses of the altered mitochondria in the alcohol-high-fat rats, having several stacked cristae at either pole and an enhanced matrix compartment. Many of the giant mitochondria have at least one expanded crista, which contains packets of helically coiled filaments. When control rats are fed carbonyl iron without ethanol, the pancreatic mitochondria display a marked propensity for forming clusters of tightly interlocked organelles, formations that may be a prelude to mitochondrial fusion. CONCLUSIONS: It appears that iron supplementation sets the stage for organelle fusion, hence enlargement, with the ethanol providing the stimulus for fusion to actually take place, and controlling the final morphology of the resultant megamitochondria.

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Membrane knobs of unfixed Plasmodium falciparum infected erythrocytes: new findings as revealed by atomic force microscopy and surface potential spectroscopy.

Cerebral malaria, a severe complication of malaria, is caused by the obstruction of cerebral microvessels by Plasmodium falciparum-infected erythrocytes. Such cells adhere to endothelial cells by means of "knobs" induced on the red cell membrane by the parasites. When atomic force microscopy was used to investigate the structure of the knobs of unfixed infected red cells, each knob was found to consist of two distinct subunits, knob components that have never been seen in chemically fixed knobs examined by conventional transmission electron microscopy. Surface potential spectroscopy revealed that the knobs have a positive charge (+20 mV), whereas the remainder of the red cell plasma membrane is negatively charged. Since endothelial plasma membranes have a negative charge, the charge difference between knobs and endothelium may play a significant role in cytoadherence between the two cell types. The subunit structure of the knobs may be a steric necessity to align adherence molecules so that they can exert their effect. This study shows that the atomic force microscope has great potential for examination of cells in their native state; in combination with surface potential spectroscopy, it may uncover fundamental processes and mechanisms in cell function.

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Cytomegalovirus in the principal submandibular gland of the little brown bat, Myotis lucifugus.

In the course of a large scale study of salivary gland ultrastructure in chiropterans, enlarged cells infected with numerous virus particles were encountered in some acinar cells in the principal submandibular glands of two of 34 little brown bats (Myotis lucifugus). The characteristic morphology of the viruses, together with the cytomegaly that they induced, led to their identification as cytomegalovirus (CMV). In a reversal of the situation in other animal species, bat virus particles within cytoplasmic vacuoles lacked capsomeres, whereas the latter were prominent in particles free in the cytosol. The generally accepted schemes for CMV production cannot explain this seemingly aberrant morphology. This report extends to four the number of mammalian orders in which CMV has been documented by means of electron microscopy as occurring in salivary glands.

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Salivary glands, cellular evolution, and adaptive radiation in mammals.

Evolutionary theory provides the foundation for interpretation of the natural world, but one remaining major challenge is to link genetic variation and particular gene products to natural selection and adaptation. Another challenge is to describe the role of cells, especially secretory cells, in the evolutionary process. Comparative studies of mammalian salivary glands could serve as an insightful model. Our theoretical approach combines data on genomic and chromosomal evolution with data on secretory cells and proteins so that adaptation can be understood in context of these interrelated components. The present paper reviews patterns and types of interspecific salivary gland cell variation that we have documented at the ultrastructural level. This data set shows ways in which secretory cells and the secretory process may have been evolutionarily modified in mammals. As a further example of our approach we also review how proline-rich-proteins (PRPs) may have had adaptive significance in the evolution of mammals, especially rodents. Our working hypotheses are: that Ca+2-binding acidic PRPs are incompatible with ever-growing dentition; and that presence or absence of tannin-binding basic PRPs was a major factor in ecological diversification in rodents. Some rodents might even exhibit behavioral compensation for absence of basic PRPs in their saliva and this illustrates the complex alternatives available to natural selection.

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Histological convergent evolution of the accessory submandibular glands in four species of frog-eating bats.

The accessory submandibular glands in four species of bats were examined by electron microscopy. These four species represent two independently evolved lineages. The fringe-lipped bat, Trachops cirrhosis, is a Neotropical phyllostomid species, whereas the false vampire bats of southeast Asia, Megaderma lyra and M. spasma, and the heart-nosed bat, Cardioderma cor, of East Africa are megadermatid species. These glands show extreme deviation from typical salivary gland histology: their secretory endpieces are in the form of follicles and their ducts lack the cytological details that permit identification of diverse duct segments. Despite their unusual histology, the secretory endpieces in M. lyra, M. spasma, and C. cor consist of secretory cells that conform to typical secretory cell morphology. In contrast, secretion by follicular cells in T. cirrhosis involves unusual cytoplasmic bodies, and their mitochondria frequently have intracristal crystalloids. Ducts in all four species consist of simple cuboidal to columnar epithelium without basal striations. Follicles and ducts in all four bats are surrounded by numerous myoepithelial cells and are heavily innervated by hypolemmal nerve terminals. Despite their widely separated geographical ranges, all four bat species consume frogs and other vertebrates. Frogs and toads often possess toxic cutaneous glands that provide a chemical defense against predation. It is postulated that the unusual accessory glands in the four frog-eating species secrete toxin-neutralizing salivary factors. The follicular form of the endpieces permits storage of preformed saliva and their coterie of myoepithelial cells and hypolemmal nerve terminals facilitates the sudden and rapid expulsion of saliva into the oral cavity during the consumption of noxious amphibians.

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Special relationship between mitochondria and hypolemmal nerve terminals in salivary glands of some bats.

BACKGROUND: Hypolemmal nerve terminals, which are abundant in many types of salivary glands, are naked axons that have penetrated the basement membrane to take up a position between adjacent parenchymal cells. Although they may form vesicle-filled varicosities, there usually are no obvious morphological indications as to which cell actually is being innervated. METHODS: Specimens of over 200 species of bats were live-trapped and their major salivary glands extirpated and prepared for electron microscopic examination. RESULTS: In 13 species of bats out of the more than 200, mitochondria-hypolemmal nerve terminal complexes were observed in different sites in different salivary glands. In these 13 species, mitochondria in epithelial cells that abut nerve varicosities are closely applied to the plasma membranes of their cells to follow the contours of these nerve elements. The complexes so formed often consist of a varicosity flanked by two mitochondria in separate cells. In intensely innervated glandular segments, mitochondria may be opposed not only to varicosities, but to the axonal portions of these nervous elements as well. CONCLUSIONS: The physiological significance of such complexes is unknown; it is conceivable that the mitochondria facilitate signal transmission or play a role in local calcium homeostasis related to nerve function.

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Plasmodium gallinaceum: a refractory mechanism of ookinete killing in the mosquito, Anopheles gambiae.

We have identified a mechanism for refractoriness to a bird malaria, Plasmodium gallinaceum, in the African vector of human malaria, Anopheles gambiae. Oocysts fail to develop in the refractory mosquitoes as a result of ookinete death which occurs within 27 hr of midgut invasion. Ultrastructural studies showed that parasite death occurs while the ookinete lies free in the midgut epithelial cell cytosol, usually surrounded by an organelle-free zone that consists of finely fibrillar material. The mechanism of parasite killing does not involve a previously described refractory mechanism of parasite encapsulation. We selected genetic lines which are refractory and susceptible to midgut infection. Genetic crossing of the lines suggests that the refractory trait is inherited as a single dominant genetic locus. Other loci probably influence oocyst number in susceptible mosquitoes. Intracellular ookinete killing appears to involve a previously unrecognized host defense mechanism against malaria parasites that involves direct destruction of the invading organism.

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Symbiotic bacteria in the accessory submandibular gland of the club-footed bat, Tylonycteris pachypus.

The lumina of the secretory endpieces and, to a lesser extent, of the duct system of the accessory submandibular gland of the club-footed bat, Tylonycteris pachypus, contain numerous rod shaped bacteria. Despite their abundance, these microbes do not evoke an inflammatory response by the glands. The major submandibular gland, as well as the other major salivary glands in these exotic animals contain no bacteria whatsoever. It is concluded that the bacteria in the accessory submandibular gland are symbionts, and that they may play a role in digestion or in the social behavior of their host organisms.

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