Spruce Budworm (Lepidoptera: Tortricidae) Oral Secretions II: Chemistry

As sessile organisms, plants have evolved different methods to defend against attacks and have adapted their defense measures to discriminate between mechanical damage and herbivory by insects. One of the ways that plant defenses are triggered is via elicitors from insect oral secretions (OS). In this study, we investigated the ability of second-instar (L2) spruce budworm [SBW; Choristoneura fumiferana (Clemens)] to alter the volatile organic compounds (VOCs) of four conifer species [Abies balsamea (L.) Mill., Picea mariana (Miller) B.S.P., Picea glauca (Moench) Voss, Picea rubens (Sargent)] and found that the emission profiles from all host trees were drastically changed after herbivory. We then investigated whether some of the main elicitors (fatty acid conjugates [FACs], β-glucosidase, and glucose oxidase) studied were present in SBW OS. FACs (glutamine and glutamic acid) based on linolenic, linoleic, oleic, and stearic acids were all observed in varying relative quantities. Hydroxylated FACs, such as volicitin, were not observed. Enzyme activity for β-glucosidase was also measured and found present in SBW OS, whereas glucose oxidase activity was not found in the SBW labial glands. These results demonstrate that SBW L2 larvae have the ability to induce VOC emissions upon herbivory and that SBW OS contain potential elicitors to induce these defensive responses. These data will be useful to further evaluate whether these elicitors can separately induce the production of specific VOCs and to investigate whether and how these emissions benefit the plant.

Carbonic anhydrase generates a pH gradient in Bombyx mori silk glands

Silk is a protein of interest to both biological and industrial sciences. The silkworm, Bombyx mori, forms this protein into strong threads starting from soluble silk proteins using a number of biochemical and physical cues to allow the transition from liquid to fibrous silk. A pH gradient has been measured along the gland, but the methodology employed was not able to precisely determine the pH at specific regions of interest in the silk gland. Furthermore, the physiological mechanisms responsible for the generation of this pH gradient are unknown. In this study, concentric ion selective microelectrodes were used to determine the luminal pH of B. mori silk glands. A gradient from pH 8.2 to 7.2 was measured in the posterior silk gland, with a pH 7 throughout the middle silk gland, and a gradient from pH 6.8 to 6.2 in the beginning of the anterior silk gland where silk processing into fibers occurs. The small diameter of the most anterior region of the anterior silk gland prevented microelectrode access in this region. Using a histochemical method, the presence of active carbonic anhydrase was identified in the funnel and anterior silk gland of fifth instar larvae. The observed pH gradient collapsed upon addition of the carbonic anhydrase inhibitor methazolamide, confirming an essential role for this enzyme in pH regulation in the B. mori silk gland. Plastic embedding of whole silk glands allowed clear visualization of the morphology, including the identification of four distinct epithelial cell types in the gland and allowed correlations between silk gland morphology and silk stages of assembly related to the pH gradient. B. mori silk glands have four different epithelial cell types, one of which produces carbonic anhydrase. Carbonic anhydrase is necessary for the mechanism that generates an intraluminal pH gradient, which likely regulates the assembly of silk proteins and then the formation of fibers from soluble silk proteins. These new insights into native silk formation may lead to a more efficient production of artificial or regenerated silkworm silk fibers.

Identification and characterization of a fatty acyl reductase from a Spodoptera littoralis female gland involved in pheromone biosynthesis

Fatty acyl-CoA reductases (FARs), the enzymes that catalyse reduction of a fatty acyl-CoA to the corresponding alcohol in insect pheromone biosynthesis, are postulated to play an important role in determining the proportion of each component in the pheromone blend. For the first time, we have isolated and characterized from the Egyptian cotton leaf worm Spodoptera littoralis (Lepidoptera: Noctuidae) a FAR cDNA (Slit-FAR1), which appeared to be expressed only in the pheromone gland and was undetectable in other female tissues, such as fat body, ovaries, wings, legs or thorax. The encoded protein has been successfully expressed in a recombinant system, and the recombinant enzyme is able to produce the intermediate fatty acid alcohols of the pheromone biosynthesis of S. littoralis from the corresponding acyl-CoA precursors. The kinetic variables Km and Vmax, which have been calculated for each acyl-CoA pheromone precursor, suggest that in S. littoralis pheromone biosynthesis other biosynthetic enzymes (e.g. desaturases, acetyl transferase) should also contribute to the final ratio of components of the pheromone blend. In a phylogenetic analysis, Slit-FAR1 appeared grouped in a cluster of other FARs involved in the pheromone biosynthesis of other insects, with little or non-specificity for the natural pheromone precursors.

Selenophosphate synthetase in the male accessory glands of an insect without selenoproteins

Selenoproteins (containing the 21st proteinogenic amino acid selenocysteine) play important roles throughout all domains of life. Surprisingly, a number of taxa have small selenoproteomes, and Hymenopteran insects appear to have fully lost selenoproteins. Nevertheless, their genomes contain genes for several proteins of the selenocysteine insertion machinery, including selenophosphate synthetase 1 (SELD/SPS1). At present, it is unknown whether this enzyme has a selenoprotein-independent function, and whether the gene is actually translated into a protein in Hymenoptera. Here, we report that SELD/SPS1 is present as a protein in the accessory glands of males of the ant Cardiocondyla obscurior. It appears to be more abundant in the glands of winged disperser males than in those of wingless, local fighter males. Mating increases the lifespan and fecundity of queens in C. obscurior, and mating with winged males has a stronger effect on queen fitness than mating with a wingless male. SELD/SPS 1 has been suggested to play an important role in oxidative stress defense, and might therefore be involved in the life-prolonging effect of mating.

Localization of α-Glucosidases I, II, and III in Organs of European Honeybees,Apis melliferaL., and the Origin of α-Glucosidase in Honey

Three kinds of alpha-glucosidases, I, II, and III, were purified from European honeybees, Apis mellifera L. In addition, an alpha-glucosidase was also purified from honey. Some properties, including the substrate specificity of honey alpha-glucosidase, were almost the same as those of alpha-glucosidase III. Specific antisera against the alpha-glucosidases were prepared to examine the localization of alpha-glucosidases in the organs of honeybees. It was immunologically confirmed for the first time that alpha-glucosidase I was present in ventriculus, and alpha-glucosidase II, in ventriculus and haemolymph. alpha-Glucosidase III, which became apparent to be honey alpha-glucosidase, was present in the hypopharyngeal gland, from which the enzyme may be secreted into nectar gathered by honeybees. Honey may be finally made up through the process whereby sucrose in nectar, in which glucose and fructose also are naturally contained, is hydrolyzed by secreted alpha-glucosidase III.

Modulation of conotoxin structure and function is achieved through a multienzyme complex in the venom glands of cone snails

The oxidative folding of large polypeptides has been investigated in detail; however, comparatively little is known about the enzyme-assisted folding of small, disulfide-containing peptide substrates. To investigate the concerted effect of multiple enzymes on the folding of small disulfide-rich peptides, we sequenced and expressed protein-disulfide isomerase (PDI), peptidyl-prolyl cis-trans isomerase, and immunoglobulin-binding protein (BiP) from Conus venom glands. Conus PDI was shown to catalyze the oxidation and reduction of disulfide bonds in two conotoxins, α-GI and α-ImI. Oxidative folding rates were further increased in the presence of Conus PPI with the maximum effect observed in the presence of both enzymes. In contrast, Conus BiP was only observed to assist folding in the presence of microsomes, suggesting that additional co-factors were involved. The identification of a complex between BiP, PDI, and nascent conotoxins further suggests that the folding and assembly of conotoxins is a highly regulated multienzyme-assisted process. Unexpectedly, all three enzymes contributed to the folding of the ribbon isomer of α-ImI. Here, we identify this alternative disulfide-linked species in the venom of Conus imperialis, providing the first evidence for the existence of a "non-native" peptide isomer in the venom of cone snails. Thus, ER-resident enzymes act in concert to accelerate the oxidative folding of conotoxins and modulate their conformation and function by reconfiguring disulfide connectivities. This study has evaluated the role of a number of ER-resident enzymes in the folding of conotoxins, providing novel insights into the enzyme-guided assembly of these small, disulfide-rich peptides.

Identification of avian wax synthases

BACKGROUND

Bird species show a high degree of variation in the composition of their preen gland waxes. For instance, galliform birds like chicken contain fatty acid esters of 2,3-alkanediols, while Anseriformes like goose or Strigiformes like barn owl contain wax monoesters in their preen gland secretions. The final biosynthetic step is catalyzed by wax synthases (WS) which have been identified in pro- and eukaryotic organisms.

RESULTS

Sequence similarities enabled us to identify six cDNAs encoding putative wax synthesizing proteins in chicken and two from barn owl and goose. Expression studies in yeast under in vivo and in vitro conditions showed that three proteins from chicken performed WS activity while a sequence from chicken, goose and barn owl encoded a bifunctional enzyme catalyzing both wax ester and triacylglycerol synthesis. Mono- and bifunctional WS were found to differ in their substrate specificities especially with regard to branched-chain alcohols and acyl-CoA thioesters. According to the expression patterns of their transcripts and the properties of the enzymes, avian WS proteins might not be confined to preen glands.

CONCLUSIONS

We provide direct evidence that avian preen glands possess both monofunctional and bifunctional WS proteins which have different expression patterns and WS activities with different substrate specificities.

[Formation of blood hydrolytic activity and exo-secrets of the digestive glands]

The results of own study and literature review about digestive glands enzymes transport into the bloodstream, simultaneous controlling exosecretion of two enzyme pools - poliglandular, recreting from blood, and new synthesized, gematoglandular recirculation of hydrolytic enzymes are presented.

Vacuolization of mucolipidosis type II mouse exocrine gland cells represents accumulation of autolysosomes

We previously reported that mice deficient in UDP-GlcNAc:lysosomal enzyme GlcNAc-1-phosphotransferase (mucolipidosis type II or Gnptab -/- mice), the enzyme that initiates the addition of the mannose 6-phosphate lysosomal sorting signal on acid hydrolases, exhibited extensive vacuolization of their exocrine gland cells, while the liver, brain, and muscle appeared grossly unaffected. Similar pathological findings were observed in several exocrine glands of patients with mucolipidosis II. To understand the basis for this cell type-specific abnormality, we analyzed these tissues in Gnptab -/- mice using a combined immunoelectron microscopy and biochemical approach. We demonstrate that the vacuoles in the exocrine glands are enlarged autolysosomes containing undigested cytoplasmic material that accumulate secondary to deficient lysosomal function. Surprisingly, the acid hydrolase levels in these tissues ranged from normal to modestly decreased, in contrast to skin fibroblasts, which accumulate enlarged lysosomes and/or autolysosomes also but exhibit very low levels of acid hydrolases. We propose that the lysosomal defect in the exocrine cells is caused by the combination of increased secretion of the acid hydrolases via the constitutive pathway along with their entrapment in secretory granules. Taken together, our results provide new insights into the mechanisms of the tissue-specific abnormalities seen in mucolipidosis type II.

[Exo- and endosecretive digestive glands of enzymes as modulators of secretion]

Enzymes, exosecreted by the digestive glands plays not only a role of the hydrolases, but also an informational and modulating role in the urgent adaptation of the enzyme secretion to the structure and properties of the luminal content of the gastrointestinal tract. Endosecreted enzymes in the blood not only inform about enzymatic condition of the hydrolase-producing glands and duct system, but also plays an informational and modulating role by the inhibition of the secretion of the same enzymes, and by the stimulation of the secretion of the heteronymic enzyme, defines a parity of their secretion and recretion, integrates enzyme secretion of the pancreas and gastric glands.

Pheromone-gland-specific fatty-acyl reductase in the adzuki bean borer, Ostrinia scapulalis (Lepidoptera: Crambidae)

The adzuki bean borer moth, Ostrinia scapulalis, uses a mixture of (E)-11- and (Z)-11-tetradecenyl acetates as a sex pheromone. At a step in the pheromone biosynthetic pathway, fatty-acyl precursors are converted to corresponding alcohols by an enzyme, fatty-acyl reductase (FAR). Here we report the cloning of FAR-like genes expressed in the pheromone gland of female O. scapulalis, and the characterization of a single pheromone-gland-specific FAR (pgFAR) and its functional assay using an insect cell expression system. As many as thirteen FAR-like genes (FAR-I-FAR-XIII) were expressed in the pheromone gland of O. scapulalis; however, only one (FAR-XIII) was pheromone-gland-specific. The deduced amino acid sequence of FAR-XIII predicted a 462-aa protein with a conserved NAD(P)H-binding motif in the N-terminal region, showing overall identity of 34% with the pgFAR of Bombyx mori. A functional assay using Sf9 cells transfected with an expression vector containing the open reading frame of the FAR-XIII gene has proven that FAR-XIII protein has the ability to convert a natural substrate, (Z)-11-tetradecenoic acid, to a corresponding alcohol, (Z)-11-tetradecenol.

Effects of the toxic dinoflagellate, Gymnodinium catenatum on hydrolytic and antioxidant enzymes, in tissues of the giant lions-paw scallop Nodipecten subnodosus

This study documents effects of the toxic dinoflagellate Gymnodinium catenatum, a producer of paralytic shellfish poison, on juvenile farmed (5.9+/-0.39 cm) giant lions-paw scallop Nodipecten subnodosus. Scallops were fed bloom concentrations of toxic dinoflagellate G. catenatum for 7 h. The effect of the toxic dinoflagellate in different tissues was determined by analysis of antioxidant enzymes (catalase, superoxide dismutase, gluthathione peroxidase), thiobarbituric acid reactive substances (lipid peroxidation), and hydrolytic enzymes (proteases, glycosidases, phosphatases, lipases, and esterases). Histopathological photos record the effects of the toxic dinoflagellate in various tissues. The results show that juvenile lions-paw scallops produce pseudo-feces, partially close their shell, increase melanization, and aggregate hemocytes. Several enzymes were affected and could serve as biological markers. In general, the adductor muscle was not affected. In the digestive gland, some enzymes could be the result of defensive and digestive processes. Gills and mantle tissue were markedly affected because these sites respond first to toxic dinoflagellates, leading to the idea that proteolytic cascades could be involved.

Assessment of environmental pollution at Balearic Islands applying oxidative stress biomarkers in the mussel Mytilus galloprovincialis

The antioxidant enzyme response of the mussel Mytilus galloprovincialis to different degree of pollution was investigated. Antioxidant enzyme activities - catalase (CAT), glutathione peroxidase (GSH-PX), glutathione reductase (GR), superoxide dismutase (SOD) - and malondialdehyde (MDA) concentration were measured in gills and digestive glands of mussels. Mussels from the same origin were transplanted along the Balearic coastal waters in eight stations characterized by a different degree of contamination and human impacts. Antioxidant enzyme activities showed an adaptive response to increase the activities in the more polluted areas. CAT, GR and SOD in gills and CAT and GR in digestive gland presented significant differences between polluted and non-polluted stations. No significant differences were observed in MDA concentration indicating that the antioxidant response is capable to avoid the lipid peroxidation. The use of biomarkers such as CAT and GR in gills and digestive glands of the mussel M. galloprovincialis is a good tool to categorize differences between polluted and non-polluted areas.

Metabolic Barrier against Bisphenol A in Rat Uterine Endometrium

Exposure to environmental chemicals with estrogenic activity during the early stage of pregnancy can seriously affect embryonic development and the maintenance of pregnancy. To estimate the metabolism and pharmacodynamics of a xenoestrogen, bisphenol A, in a reproductive organ, the metabolite of bisphenol A was analyzed after incubating a rat uterine sac in buffer solutions containing the chemical. When the inner or the outer side of the uterine sac was exposed to bisphenol A, the concentration of the parent chemical was decreased in buffer solution and then, only one metabolite, bisphenol A-glucuronide, was observed only in the outer, that is, the maternal, side. A small amount of the parent chemical could pass through the uterine sac without being modified. Uridine diphosphate (UDP)-glucuronosyltransferase (UGT) was shown by immunohistochemical staining analysis to be distributed in epithelial cells of the endometrium, oviduct, and uterine glands. Based on measurements of enzyme activity and on Western blot analysis, UGT activity toward bisphenol A and UGT protein were identified in the microsomal fractions prepared from rat uterus. UGT isoforms, such as UGT1A1, 1A2, 1A5, 1A6, and 1A7, were expressed, and MRP-1 (multidrug resistance-associated protein) and MRP-3, which are well-known to be transporters of various drug-glucuronides, were detected in the rat uterus by reverse transcription-PCR. These results elucidate the rat uterine barrier system by showing that most bisphenol A perfused into the uterus was glucuronidated in the epithelium, resulting in transport of glucuronides to the maternal side.

Hydrolases in the hypopharyngeal glands of workers of Scaptotrigona postica and Apis mellifera (Hymenoptera, Apinae)

Hydrolytic enzymes from hypopharyngeal gland extracts of newly emerged, nurse and foraging workers of two eusocial bees, Scaptotrigona postica, a native Brazilian stingless bee, and the Africanized honey bee (Apis mellifera) in Brazil, were compared. The hypopharyngeal gland is rich in enzymes in both species. Fifteen different enzymes were found in the extracts, with only a few quantitative differences between the species. Some of the enzymes present in the extracts may have intracellular functions, while others seem to be digestive enzymes. Scaptotrigona postica, had lower beta-glucosidase and higher lipase esterase activities than A. mellifera. The differences may be due to different feeding habits and behavioral peculiarities of the two species.

Expression of Aromatase mRNA in the Abdominal Gland of the Newt,Cynops pyrrhogaster

As a step to see whether the local aromatization mechanism exists in the newt, Cynops pyrrhogaster, cDNA cloning and characterization of newt cytochrome P450 aromatase (P450arom) were conducted. Newt P450arom cDNA was obtained from a C. pyrrhogaster ovarian cDNA library. By RT-PCR and in situ hybridization, an intense P450arom mRNA expression was detected in the abdominal gland. Employing biochemical techniques combined with HPLC and TLC analyses, we also demonstrated the conversion of testosterone to estradiol in the abdominal grand. The significance of aromatization of testosterone in this gland is discussed.

Penaeus vannamei isotrypsins: purification and characterization

Three isotrypsins from digestive gland of Penaeus vannamei were purified and characterized by molecular, biochemical and kinetic parameters. Purified isotrypsins A, B, and C are glycoproteins with molecular masses between 30.2 and 32.9 kDa, and, therefore similar to other trypsins. The isoelectric points are anionic and different among the three isotrypsins: pH 3.5 for isotrypsin A, pH 3.0 for isotrypsin B, and pH 4.5 for isotrypsin C. Differences in the NH(2)-terminal amino acid sequences allowed us to define three different protein entities that match isotrypsins previously deduced by cDNA. Isoform C has higher physiological efficiency and specific activity, lower K(m), and requires higher concentrations of Ca(+2) to reach the same activity as the other two isotrypsins.

Purification and characterization of a saccharide-binding protein from penetration glands of Diplostomum pseudospathaceum--a bifunctional molecule with cysteine protease activity

A beta-1,3-glucan-binding lectin from the penetration glands of Diplostomum pseudospathaceum cercariae was isolated by affinity chromatography using yeast glucan and curdlan as affinity matrices. Further purification to homogeneity was performed by cation-exchange chromatography. The protein migrated as a double band around 24 kDa in gels after SDS-PAGE. The protein is of strongly basic nature--its pI shown by native IEF was around 10. The mass of the protein determined by MALDI-TOF mass spectrometry was 23.9 kDa. N-terminal sequence as well as some internal sequences showed significant alignments with several cysteine protease sequences found in databases. The protein bound a biotinylated synthetic analogue of the irreversible inhibitor of cysteine proteases, E-64 and, moreover, its proteolytic activity was demonstrated in substrate gels. The enzymatic activity could be inhibited by the cysteine protease inhibitor E-64; therefore, the investigated protein was considered to be a bifunctional molecule possessing both lectin and enzyme activities. Glycanohydrolytic activity was not proved. The detected characters of this molecule lead to a hypothesis on its role in penetration of Diplostomum cercariae into fish hosts--that of binding to the carbohydrates of fish mucus and concurrent cleaving of protein components of the mucus and skin.

Molecular characterization of a male-specific glycosyl hydrolase, Lma-p72, secreted on to the abdominal surface of the Madeira cockroach Leucophaea maderae (Blaberidae, Oxyhaloinae)

The epicuticular surface protein Lma-p72 is specific to the abdominal secretions of Leucophaea maderae (Madeira cockroach) adult males. Natural Lma-p72 was purified and the complete cDNA sequence determined by reverse-transcription PCR using primers based on Edman degradation fragments. Northern blot and in situ hybridization analyses showed that Lma-p72 was expressed in the tergal and sternal glands. Sequence alignment indicates that Lma-p72 is closely related to the family 1 glycosyl hydrolases (EC 3.2.1). Native Lma-p72 was proved to be active in the abdominal secretions and exhibit a beta-galactosidase-like activity. However, weak specificity with respect to the C-4 configuration of the substrate was observed. Two main hypotheses were proposed concerning the function of this enzyme: Lma-p72 could hydrolyse oligosaccharides from the male abdominal secretions, making them more phagostimulatory for the female during the precopulatory behaviour. The protein could also cleave a pheromone-sugar conjugate to release the pheromonal compounds on to the cuticular surface. Such a sugar conjugate could be a transport form. Data from the first in vivo inhibition tests indicate that a glycosidase could be directly involved in the production process of some pheromonal compounds in L. maderae males.

[Recretion of enzymes and hormones by exocrine glands]

The article reviews a poorly explored issue of secretive physiology-recretion from blood by glandulocites of various endocrinal glands of hydrolytic ferments and hormones that have been synthesized by digestive and endocrinal glands. The article discusses potential physiological role of the recretion function and the diagnostic significance of information obtained from analysis of recreted ferments and hormones in exosecretions.

Immunolocalization of venom metalloproteases in venom glands of adult and of newborn snakes of Bothrops jararaca

Using immunoelectronmicroscopy we analyzed qualitative and quantitatively the intracellular distribution of bothropasin, hemorrhagic factor 2 (HF2) and hemorrhagic factor 3 (HF3) in the venom secretory cells from adult snakes in the active (7 days after venom extraction) and in the resting (without venom extraction for 40 days) stages of protein synthesis. Glands from the newborn Bothrops jararaca were also studied. The results lead to the conclusion that all the secretory cells and the secretory pathway in the cells are qualitatively alike in regard to their content of the three metalloproteases. Secretory cells from the resting glands, unlike the active ones and the newborn glands, did not present immunolabeling in the narrow intracisternal spaces of the rough endoplasmic reticulum (RER). The label intensity for bothropasin was greater than that for the other proteins in the adults. HF3 and HF2 labeling densities in the newborn were higher than in the adults and HF3 labeling was not different from that of bothropasin. Co-localization of the three metalloproteases was detected in the RER cisternae of the active gland secretory cells, implying that mixing of the proteases before co-packaging into secretory vesicles occurs at the beginning of protein synthesis in the RER cisternae.

Cytochemical localization and quantification of plasma membrane Ca2+-ATPase activity in mollusc digestive gland cells

A cytochemical method allowing the localization and quantification of plasma membrane Ca2+-ATPase (PMCA) in frozen sections obtained from digestive gland cells of Mytilus galloprovincialis, Tapes tapes and Chamelea gallina, is presented. The method utilizes lead as a trapping agent of PO4(2-) ions released by Ca2+-ATPase activity. The amount of lead sulphide precipitate proportionally related to PMCA activity was quantified by a light microscopy digital imaging analysis system. The optimal assay conditions of Ca2+-ATPase activity evaluated at pH 7.4 were: 200 microM free Ca2+, 200 mM KCl, 2 mM ATP, and under such analysis conditions the enzyme showed a linear trend up to 60 min (at 20 degrees C). The PMCA activity was substrate specific: ADP was utilized only at a low rate (24% with respect to an equimolar ATP concentration), while glucose-6-phosphate and beta-glycerophosphate were poorly hydrolyzed. The enzyme activity was strongly inhibited by sodium ortho-vanadate. Our detection of a Ca2-ATPase activity at nanomolar concentrations of free Ca2+ suggests that we have identified a plasma membrane Ca2-ATPase involved in Ca2+ homeostasis. The Ca2+-ATPase was found to be localized in the basal part of the plasma membrane in the digestive gland cells of Mytilus galloprovincialis and Tapes tapes, but in the apical plasma membrane of Chamelea gallina. The possible implications of the different cellular distributions of PMCA activity is discussed.

Identification of proteases in the extract of venom glands from brown spiders

In the present investigation, in order to dispute the rational criticism against the presence of proteolytic enzymes in the electrostimulated venom obtained from spiders of the genus Loxosceles, as a consequence of contamination with abdominal secretions, venoms of L. intermedia and L. laeta were directly collected from venom glands by microdissection and gentle homogenization. Gel electrophoresis stained by silver method carried out to compare L. intermedia electrostimulated venom and venom gland extract demonstrated no significant differences in protein profile. Zymogram analysis of L. intermedia venom gland extract detected a gelatinolytic activity in the 32-35 kDa region. The inhibitory effect of 1,10-phenanthroline on this proteolytic activity further supported its metalloprotease nature. In proteolytic digestion experiments L. intermedia venom gland extract was also able to cleave purified fibronectin and fibrinogen. The inhibitory effect of 1,10-phenanthroline on these degrading activities confirmed the presence of metalloproteases in the venom. In addition, when purified fibrinogen was incubated with L. intermedia abdominal extract, the fibrinogenolysis was completely different, generating low mass fragments that ran away from the gel, a proteolytic event not blocked by 1,10-phenanthroline. Zymogram experiments using L. laeta venom gland extracts further detected a gelatinolytic band at 32-35 kDa, also inhibited by 1,10-phenanthroline, confirming the presence of metalloproteases in both species.

Enhancement of the chemoprotective enzymes glucuronosyl transferase and glutathione transferase in specific organs of the rat by the coffee components kahweol and cafestol

The coffee components kahweol and cafestol (K/C) have been reported to protect the colon and other organs of the rat against the formation of DNA adducts by 2-amino-1-methyl-6-phenylimidazo[4,5- b]pyridine (PhIP) and aflatoxin B1. PhIP is a cooked-food mutagen to which significant human exposure and a role in colon cancer etiology are attributed, and, interestingly, such cancers appear to develop at a lower rate in consumers of coffees with high amounts of K/C. Earlier studies in rodent liver have shown that a key role in the chemopreventive effect of K/C is likely to be due to the potential of these compounds to induce the detoxification of xenobiotics by glutathione transferase (GST) and to enhance the synthesis of the corresponding co-factor glutathione. However, mutagens like PhIP may also be detoxified by UDP-glucuronosyl transferase (UDPGT) for which data are lacking regarding a potential effect of K/C. Therefore, in the present study, we investigated the effect of K/C on UDPGT and, concomitantly, we studied overall GST and the pattern of individual GST classes, particularly GST-theta;, which was not included in earlier experiments. In addition, we analyzed the organ-dependence of these potentially chemopreventive effects. K/C was fed to male F344 rats at 0.122% in the chow for 10 days. Enzyme activities in liver, kidney, lung, colon, salivary gland, pancreas, testis, heart and spleen were quantified using five characteristic substrates and the hepatic protein pattern of GST classes alpha, mu, and pi was studied with affinity chromatography/HPLC. Our study showed that K/C is not only capable of increasing overall GST and GST classes alpha, mu, and pi but also of enhancing UDGPT and GST-theta. All investigated K/C effects were strongest in liver and kidney, and some response was seen in lung and colon but none in the other organs. In summary, our results show that K/C treatment leads to a wide spectrum of increases in phase II detoxification enzymes. Notably, these effects occurred preferentially in the well perfused organs liver and kidney, which may thus not only contribute to local protection but also to anti-carcinogenesis in distant, less stimulated organs such as the colon.

Distribution of acid phosphatases in the hypopharyngeal glands from workers, queens and males of a Brazilian stingless bee Scaptotrigona postica Latreille: an ultrastructural cytochemical study

The present study reports the localization of acid phosphatase in the hypopharyngeal gland cells from workers (newly-emerged, nurse and forager), queens (newly-emerged and laying) and males (newly-emerged and mature for mating) of the Brazilian stingless bee, Scaptotrigona postica. The phosphatase activity varied in intensity and localization depending on the individual class, physiological age and the substrate used. In newly-emerged workers, the phosphatase-positive sites suggest the involvement of the enzyme with cellular differentiation that occurs in the presecretory phase, in nurse workers with protein synthesis and in forager workers with changes in cellular activity or glandular regression. In males mature for mating and laying queens, the positive sites are related to secretory activity, showing that the gland maintains some activity in spite of the regressive aspect. Of the substrates used, beta-glycerophosphate gave the least specific localization.

Disrupted carbonic anhydrase distribution in the avian shell gland following in ovo exposure to estrogen

Eggshell thinning among wild birds has been an environmental concern for almost half a century and the underlying mechanisms are still not fully understood. Previously we showed that exposure of quail embryos to ethynylestradiol (EE2) caused disorganization of the tubular glands in the shell gland of adult birds. In this study, we have examined the effect of in ovo exposure to EE2 on carbonic anhydrase (CA) localization, especially in the shell gland, because CA is required for shell formation. In the control birds, CA was localized in the cell membranes of the tubular gland cells of the shell gland, whereas the surface epithelium was always devoid of CA. In ovo treatment with 20ng EE2/g egg resulted in a loss of CA activity in the tubular glands while the surface epithelium showed strong induction of both membrane bound and cytoplasmic CA activity in 49+/-1% of the cells. The dose 2ng EE2/g egg resulted in partial loss of tubular gland CA and strong induction of CA activity in 2.5+/-0.5% of the surface epithelial cells and weaker induction in 22+/-2% of the epithelial cells. In conclusion, this study shows that embryonic exposure to a xenoestrogen disrupts CA distribution in the adult shell gland. We propose that eggshell thinning in avian wildlife could reflect a functional malformation in the shell gland, already induced by xenoestrogen during embryonic development rather than being caused solely by exposure of the adult bird.

Involvement of Cathepsin B- and L-Like Proteinases in Silk Gland Histolysis during Metamorphosis of Bombyx mori

To identify proteinases involved in programmed cell death of the silk glands of Bombyx mori, we measured enzyme activities in silk gland homogenates. Several peptidyl-4-methylcoumaryl-7-amides (MCAs) and bovine hemoglobin were used as substrates in the presence and absence of proteinase inhibitors. The hydrolysis of t-butyloxycarbonyl-Phe-Ser-Arg-MCA (Boc-FSR-MCA), benzyloxy-carbonyl-Phe-Arg-MCA (Z-FR-MCA), and Z-Arg-Arg-MCA (Z-RR-MCA) was optimal at pH 5.5, 5.0, and 5.5, respectively. It was stimulated by the sulfhydryl compounds or EDTA and inhibited by both cysteine proteinase inhibitors and a cathepsin B-specific inhibitor, l-3-trans-(propyl-carbamoyl)oxirane-2-carbonyl)-L-isoleucyl-L-prolin (CA-074). The hemoglobin hydrolysis at the optimum pH 3.5 was inactivated by cysteine proteinase inhibitors, but stimulated slightly by pepstatin. The cleavage of Arg-MCA (R-MCA) and Leu-MCA (L-MCA) at optimum pH of 7.0 was strongly inhibited by an aminopeptidase inhibitor, puromycin, and by sulfhydryl compounds. The Boc-FSR-MCA, Z-FR-MCA, Z-RR-MCA, and hemoglobin hydrolyzing activities increased in the silk glands dramatically after cocoon formation, while the R-MCA and L-MCA cleaving activities declined. The results strongly suggest the involvement of cathepsin B- and cathepsin L-like proteinases in the histolysis of the silk gland during metamorphosis.

The expression of gastric H+-K+-ATPase mRNA and protein in developing rat fundic gland

The proton pump H+-K+-ATPase is the final common pathway mediating the production and secretion of hydrochloric acid by gastric parietal cells. The present studies were undertaken to examine whether the expression of gastric H+-K+-ATPase mRNA and protein changes are associated with the development of H+-K+-ATPase activity in the rat fundic gland. H+-K+-ATPase activity was examined in rat fundic gland at different stages from gestational day 18.5 to postnatal 8 weeks. The expression of H+-K+-ATPase mRNA was detected by in situ hybridization using a digoxigenin-labelled RNA probe with a tyramide signal amplification system. The expression of H+-K+-ATPase protein was evaluated by immunoblotting and immunohistochemistry using antibodies against H+-K+-ATPase alpha- and beta-subunits. We found that H+-K+-ATPase enzyme activity was detectable from the onset of gland formation (day 19.5 of gestation) and increased with age in the developing rat fundic gland. Expression of mRNA and protein was also discernible at the same time, and a progressive increase in expressions was observed as rats developed. Our results suggested that in developing rat fundic gland, the expression of both mRNA and protein of H+-K+-ATPase increased with age in a manner that parallels the development of H+-K+-ATPase enzyme activity.

Immunolocalization of four antioxidant enzymes in digestive glands of mollusks and crustaceans and fish liver

The aim of this work was to determine the immunolocalization of the antioxidant enzymes catalase, Cu,Zn-superoxide dismutase (SOD), Mn-SOD, and glutathione peroxidase (GPX) in the bivalve mollusks Mytilus galloprovincialis and Crassostrea sp., the crab Carcinus maenas, and the teleostean fish Mugil cephalus. By immunoblotting, crossreactivity between antibodies and the corresponding proteins in the digestive gland/hepatopancreas of invertebrates and the fish liver was demonstrated. Immunohistochemical studies showed that the stomach epithelium was strongly immunostained for catalase in mollusks. In crabs, ducts showed stronger immunostaining than tubules and in mullet hepatocytes the reaction appeared in discrete granules corresponding to peroxisomes. With regard to Cu,Zn-SOD, the apex of the tubule cells in mussels and crabs was distinctly immunostained, whereas in oysters the reaction was more marked in ducts and in mullet liver a uniform diffuse cytoplasmic staining was found. Mn-SOD was strongly positive in mollusk and crab ducts and in mullet periportal hepatocytes. Finally, GPX was not detected in mussels while in oysters a slight reaction was noted in all cell types. In crabs, connective tissue cells and the apex of duct cells were immunostained, but in mullet liver only erythrocytes appeared reactive. Immunoelectron microscopy revealed that catalase was localized in peroxisomes with a dense labeling in fish and less intense labeling in invertebrates. Cu,Zn-SOD was mainly a cytosolic protein although additional positive subcellular sites (peroxisomes, nuclei) were also observed, while Mn-SOD was restricted to mitochondria. GPX was localized in the cytosol, nucleus, and lysosomes, occurring also in peroxisomes of the fish liver. The results presented here provide a basis for future application of the immunodetection techniques to study the possible differential induction of antioxidant enzymes in aquatic organisms subjected to oxidative stress as a result of exposure to environmental pollutants.

Effect of the dietary brominated phenol, lanasol, on chemical biotransformation enzymes in the gumboot chiton Cryptochiton stelleri (Middendorf, 1846)

The effects of diet and other non-anthropogenic stressors on biochemical defenses and their relationship to susceptibility have been largely ignored in wildlife populations. Lanosol is a compound found in relatively high amounts in various marine species of Rhodophyta, including Odonthalia dentata. While previous studies demonstrated that lanosol is a feeding deterrent to several marine herbivores, Cryptochiton stelleri readily feeds upon O. dentata. To examine the effects of lanosol on the profile of biochemical defenses in C. stelleri, chitons were gavaged daily with 0, 1, 2.5, 5, or 10 mg/kg of lanosol. After three days of exposure, digestive gland microsomes were probed for expression of homologous isoforms of cytochromes P450 (CYP1A, CYP3A, and CYP2) and phase II enzymatic activities. Expression of a 43 kDa CYP3A-like protein was increased by approximately 45%, over control following 2.5, 5, and 10 mg/kg treatments. Estradiol hydroxylase activity tended to increase with the dose of lanosol. UDP-glucuronosyl transferase activity was highly variable but appeared to increase at the two highest treatments, while sulfotranserase activity was significantly decreased at the three highest doses. Kinetic studies of GST activity showed lanosol is a non-competitive inhibitor of both CDNB and GSH in the GST-mediated conjugation reaction. These results show that dietary exposure to the brominated-phenol, lanosol, may alter expression and activity of some phase I and II biotransformation enzymes in chitons, potentially providing a dietary advantage for the species.

Effect of 24 hours light on circadian rhythms of secretory enzymes and morphology of rat von Ebner's glands

Von Ebner's glands of the rat are minor salivary serous glands in the posterior portion of the tongue. They secrete two digestive enzymes, lingual lipase and amylase. In this investigation, circadian rhythm in feeding was established under a normal 12 h light/12 h dark cycle, with the rats eating primarily during the dark period. At lights on, the size of the acinar cells and the area of the inclusive secretory granules, and the amount of digestive enzyme activity (lingual lipase and amylase) remaining in the gland was significantly less than in the mid-afternoon, after very little daylight food consumption. However, after 7 days of continuous light the circadian rhythm was altered: the food consumption during the normal night-time hours (5 p.m. to 8 a.m.) went from 88% of total 24 h food consumption to 45%, and during normal daylight hours (8 a.m. to 5 p.m.) from 12% to 55%. These changes were correlated with histometric findings of a near reversal of the areas of acinar cells and secretory granules of a.m. and p.m. samples under continuous light. Lingual lipase activity in the glands went from 35% under 12 h light to 61% under continuous light in the a.m. and from 65% to 39% in the p.m. Amylase activity also showed nearly a reversal in activity remaining in the gland, from 36% at 12 h light to 58% at 24 h light in the a.m. and 64% to 41% for the p.m. samples. These results indicate that the von Ebner's glands of the rat have a circadian rhythm of secretion and storage of secretory proteins that is subject to light entrainment similar to that seen in other exocrine glands such as the parotid and pancreas.

Expression of amylase and glucose oxidase in the hypopharyngeal gland with an age-dependent role change of the worker honeybee (Apis mellifera L.)

Worker honeybees change their behaviour from the role of nurse to that of forager with age. We have isolated cDNA clones for two honeybee (Apis mellifera L.) genes, encoding alpha-amylase and glucose oxidase homologues, that are expressed in the hypopharyngeal gland of forager bees. The predicted amino acid sequence of the putative Apis amylase showed 60.5% identity with Drosophila melanogaster alpha-amylase, whereas that of Apis glucose oxidase showed 23.8% identity with Aspergillus niger glucose oxidase. To determine whether the isolated cDNAs actually encode these enzymes, we purified amylase and glucose oxidase from homogenized forager-bee hypopharyngeal glands. We sequenced the N-terminal regions of the purified enzymes and found that they matched the corresponding cDNAs. mRNAs for both enzymes were detected by Northern blotting in the hypopharyngeal gland of the forager bee but not in the nurse-bee gland. These results clearly indicate that expression of the genes for these carbohydrate-metabolizing enzymes, which are needed to process nectar into honey, in the hypopharyngeal gland is associated with the age-dependent role change of the worker.

A calcium/calmodulin-dependent nitric oxide synthase, NMDAR2/3 receptor subunits, and glutamate in the CNS of the cuttlefish Sepia officinalis: localization in specific neural pathways controlling the inking system

Chemical, biochemical, and immunohistochemical evidence is reported demonstrating the presence in the brain of the cuttlefish Sepia officinalis of a Ca2+-dependent nitric oxide synthase, NMDAR2/3 receptor subunits, and glutamate, occurring in neurons and fibers functionally related to the inking system. Nitric oxide synthase activity was concentrated for the most part in the cytosolic fraction and was masked by other citrulline-forming enzyme(s). The labile nitric oxide synthase could be partially purified by ammonium sulfate precipitation of tissue extracts, followed by affinity chromatography on 2',5'-ADP-agarose and calmodulin-agarose. The resulting activity, immunolabeled at 150 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis by antibodies to rat neuronal nitric oxide synthase, depended on NADPH and tetrahydro-L-biopterin, and was inhibited by N(G)-nitro-L-arginine. NMDAR2/3 subunit-immunoreactive proteins migrating at 170 kDa could also be detected in brain extracts, along with glutamate (whole brain: 0.32 +/- 0.03 micromol of glutamate/mg of protein; optic lobes: 0.22 +/- 0.04; vertical complex: 0.65 +/- 0.06; basal lobes: 0.58 +/- 0.04; brachial lobe: 0.77 +/- 0.06; pedal lobe: 1.04 +/- 0.08; palliovisceral lobe: 0.86 +/- 0.05). Incubation of intact brains with 1.5 mM glutamate or NMDA or the nitric oxide donor 2-(N,N-diethylamino)diazenolate-2-oxide caused a fivefold rise in the levels of cyclic GMP, indicating operation of the glutamate-nitric oxide-cyclic GMP signaling pathway. Immunohistochemical mapping of Sepia CNS showed specific localization of nitric oxide synthase-like and NMDAR2/3-like immunoreactivities in the lateroventral palliovisceral lobe, the visceral lobe, and the pallial and visceral nerves, as well as in the sphincters and wall of the ink sac.

Renin in exocrine glands of different mouse strains

The renin-angiotensin system (RAS) controls the regulation of blood pressure and water-mineral balance. Recently, renin has been reported to be synthesized and secreted outside the kidney. The present study investigated immunohistochemically the distribution of renin in exocrine glands, i.e. salivary glands and coagulating glands, in male mice of 13 strains. In some strains, renin was detected in the sublingual and submandibular salivary glands, but not in the parotid glands. It was restricted to the striated or granular portions of excretory ducts. In coagulating glands, variable staining patterns were found. These results demonstrate the existence of variations in renin content in mouse strains and offered a selection of mouse strains for investigation of exocrine gland renin.

The endocrine secretion of mammalian digestive enzymes by exocrine glands

The exocrine pancreas and certain salivary glands of mammals secrete a variety of enzymes into the gastrointestinal tract, where they digest food. The same glands also release these enzymes into the bloodstream. This latter process has commonly been assumed to occur solely as the result of a pathological condition or as an inadvertent by-product of exocrine secretion due to the leakage of trace quantities of the enzymes into blood. However, a variety of evidence suggests that the endocrine secretion of digestive enzymes is a normal occurrence that can be of substantial magnitude in healthy individuals, is responsive to various physiological stimuli, and is distinct from exocrine secretion. Recent research has focused attention on this process as a promising means for the delivery of engineered proteins into the systemic circulation for pharmaceutical purposes. In this review, we survey research in this area and consider the evidence for the existence of an endocrine secretion of digestive enzymes, the cause of enzyme release into the bloodstream, its source within the tissue, and, finally, the physiological purposes that this secretion process might serve.

Excessive synthesis of matrix metalloproteinases in exocrine tissues of NOD mouse models for Sjögren's syndrome

OBJECTIVE

Matrix metalloproteinases (MMP) and their substrates, components of the extracellular matrix, regulate environmental signals for cellular differentiation and tissue function. Changes in the levels of these enzymes may influence cell survival as well as pathology involving ectopic apoptosis. Using the non-obese diabetic (NOD) mouse model for Sjögren's syndrome, we evaluated the synthesis and expression of MMP in the exocrine target tissues of autoimmunity.

METHODS

NOD, immunodeficient NOD-scid, and nondiabetic NOD.B10.H2b mice were evaluated for MMP activity in their saliva and exocrine gland lysates by gelatin zymography and reverse transcriptase-polymerase chain reaction (RT-PCR). In addition, changes in protein content of saliva and gland lysates were determined by specific Western blot and by enzymatic activity of amylase and cysteine proteases. Mice continuously treated with the MMP inhibitor GM6001 were evaluated from 7 to 20 weeks of age for the contribution of MMP activity to development of these hallmark biochemical markers of Sjogren's syndrome-like disease of NOD mice.

RESULTS

Gelatin zymography of whole saliva and gland lysates indicated the presence of increased proteolytic activity, corresponding to proteins with a molecular mass ranging from 50 to 95 kDa, in the saliva of older (> 20 weeks of age) NOD mice as well as NOD.B10.H2b and NOD-scid mice compared to BALB/c controls. Elevated steady state levels of mRNA transcripts for the gelatinases MMP-2 and MMP-9 were detected in total RNA extracted from parotid and submandibular glands by RT-PCR. Despite prophylactic injection of the broad spectrum MMP inhibitor GM6001 into mice beginning at 7 weeks of age and continuing to 20 weeks, development of the autoimmune exocrinopathy was neither stopped nor retarded.

CONCLUSION

These observations suggest that excessive MMP activity is associated with autoimmune Sjögren's syndrome-like disease in NOD mice. However, a possible contribution by increased MMP activity in initiation and progression of this autoimmune disease is yet to be elucidated.

Divergent and common groups of proteins in glands of venomous snakes

Protein contents of venom-producing glands from the sea-snake Laticauda colubrina (LC) and terrestrial Vipera Russelli (VR) were studied using high-resolution two-dimensional gels: isoelectric focusing followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (IEF/SDS-PAGE) and nonequilibrium pH gradient electrophoresis (NEPHGE) followed by SDS-PAGE. Tentative identities of numerous proteins were established using their amino acid compositions and in certain cases the identities were verified by microsequencing of their N-terminals and internal fragments. As expected, we found several proteins known to be present in the venom of the respective snakes. These include numerous isoforms of phospholipase A2 (PLA2) in both snake glands, various neurotoxins in LC glands and factor IX/factor X-binding protein, hemorrhagic factor and coagulation factor X activating enzyme in Russell's viper glands (VR). Not unexpectedly, we also found a number of cell housekeeping proteins, cytoskeletal proteins, proteins that are necessary for folding, such as heat-shock proteins, protein disulfide-isomerase and peptidyl-prolyl cis/trans isomerases. Unexpectedly, however, the glands of Laticauda colubrina and Russell's viper include a large quantity of antihemorrhagic factor and inhibitor of PLA2, respectively, that have been previously described in snake plasma. The possible reason associated with the presence of these components in venom glands is discussed.

Schistosoma mansoni cercariae: stimulation of acetabular gland secretion is adapted to the chemical composition of mammalian skin

The chemical signals of mammalian skin that stimulate the secretion of acetabular gland contents of Schistosoma mansoni cercariae were determined by exposing cercariae to fractions of human and pig skin surface obtained by thin-layer chromatography. Postacetabular gland secretion was stimulated by hydrophilic skin extracts but was often combined with a secretion of preacetabular glands. Secretion of preacetabular glands, which contain enzymes for skin lysis, could be selectively stimulated with skin surface lipids. Two different mechanisms of lipid-stimulated preacetabular gland release could be distinguished. First, secretion in combination with penetration behavior and probably tegument transformation was stimulated by the fraction of free fatty acids. Second, secretion independent of penetration behavior and tegument transformation was exclusively stimulated by glucosylceramides and phospholipids, probably phosphatidylcholines. The secretion mechanisms seem to allow a continuous lysis of epidermal macromolecules during the skin passage of the cercariae. Free fatty acids occur in the uppermost skin layers and may stimulate the combination of the first response; phospholipids and glucosylceramides are restricted to deeper epidermal layers and may stimulate the enzyme secretion there. An active preacetabular gland release was also stimulated by toxic chemicals, which could suggest an emergency penetration program for impaired cercariae.

A calcium-dependent nitric oxide synthase and NMDA R1 glutamate receptor in the ink gland of Sepia officinalis: a hint to a regulatory role of nitric oxide in melanogenesis?

Histochemical, immunohistochemical, and biochemical evidence is reported showing that the ink gland of the cuttlefish Sepia officinalis contains a calcium-dependent isoform of nitric oxide synthase as well as an NMDA R1 receptor subunit localized for the most part in the immature inner cells of the epithelial layer of the gland. These results may be taken to implicate a hitherto unrecognized regulatory role of the glutamate-nitric oxide pathway in the maturation and metabolic activity of melanin-producing cells in the cephalopod defense system.

Subcellular localization and function of melanogenic enzymes in the ink gland of Sepia officinalis

The ink gland of the cuttlefish Sepia officinalis has traditionally been regarded as a convenient model system for investigating melanogenesis. This gland has been shown to contain a variety of melanogenic enzymes including tyrosinase, a dopachrome-rearranging enzyme and peroxidase. However, whether and to what extent these enzymes co-localize in the melanogenic compartments and interact is an open question. Using polyclonal antibodies that recognize the corresponding Sepia proteins, we have been able to demonstrate that peroxidase has a different subcellular localization pattern from tyrosinase and dopachrome-rearranging enzyme. Whereas peroxidase is located in the rough endoplasmic reticulum and in the matrix of premelanosomes and melanosomes, tyrosinase and dopachrome-rearranging enzyme are present in the rough endoplasmic reticulum-Golgi transport system, at the level of trans-Golgi cisternae, trans-Golgi network and coated vesicles, and in melanosomes on pigmented granules. These results fill a longstanding gap in our knowledge of the melanin-producing system in Sepia and provide the necessary background for dissection at the molecular level of the complex interaction between melanogenic enzymes. Moreover, the peculiar and complex organization of melanin in an invertebrate such as Sepia officinalis is surprising and could provide the basis for understanding the process in more evolved systems such as that of mammals.

Differentially regulated epithelial expression of an Eph family tyrosine kinase (fHek2) during tracheal surface airway and submucosal gland development

A ferret model was used to evaluate the potential role of an Eph family tyrosine kinase (fHek2) in tracheal development of surface airway epithelium and submucosal glands. A partial 2.6-kb cDNA fragment of fHek2 was isolated from a ferret tracheal/lung cDNA library. Sequence analysis demonstrated that this gene is the ortholog to the previously cloned human Hek2 gene. In situ hybridization analysis of fHek2 mRNA expression on ferret tracheal developmental time points revealed an expression pattern within a subset of surface airway epithelial cells which remained relatively constant throughout tracheal development (from -2 d in utero to adult). In contrast, developing tracheal submucosal glands at 3-day postnatal time points demonstrated little fHek2 mRNA expression. However, expression of fHek2 significantly increased more than 4-fold over the course of gland development to adulthood. These findings, which demonstrate a uniquely regulated pattern of fHek2 mRNA expression between surface airway epithelium and submucosal glands, have implications on regulatory processes which control differentiation and/or maturation of secretory structures in the lung. Such findings may be useful in further delineating the mechanisms which control cellular differentiation in the lung and how these processes are abnormally regulated in hypersecretory diseases such as chronic bronchitis, asthma, and cystic fibrosis.

[The regulatory role of enzymes exo- and endosecreted by the digestive glands]

Publications and our own results of researches into the role of enzymes exo- and endosecreted by digestive glands, acting as regulators of their secretion and motor activity of gastroduodenal complex were summarized. Exosecreted to its cavity enzymes adapt an enzymatic spectrum of secretes to the composition and properties of duodenal content through M-cholinergic, peptidergic, and beta-adrenoceptive mechanisms on the basis of reception of the complex properties: enzyme-substrate-product. We described the effect of enzymes on the glands producing them, and the influence on secretion of the other digestive glands, regulatory effects of peptide fragments of proteolytic enzymes, and their zymogenic precursors. The digestive glands enzymes endosecreted and circulated in blood produce a hindrancing and inducing effect on these glands, take part in supporting of homeostasis of organism. Mechanisms of influence of enzymes and their fragments on the activity of digestive glands were analysed.

The effect of a nitric oxide donor and an inhibitor of nitric oxide synthase on blood flow and vascular resistance in feline submandibular, parotid and pancreatic glands

The aim was to examine whether (1) blood flow and vascular resistance are altered in response to exogenous nitric oxide and (2) whether endogenous synthesis of nitric oxide participates in the haemodynamic regulation of the submandibular, parotid and pancreatic glands. Experiments were performed on anaesthetized, artificially ventilated cats. Mean arterial blood pressure, heart rate, blood gases, cardiac output and tissue blood flow were determined before and 15 min after intravenous administration of either the nitric oxide donor SIN-1 (3-morpholinosydnonimine, 1 mg/kg, n = 10) or the competitive nitric oxide synthase inhibitor NOLA (NG-nitro-L-arginine, 30 mg/kg, n = 9) blood flow was measured by a radioactive-labelled microsphere method. In the SIN-1 group, in spite of a serious decrease in mean arterial blood pressure (p < 0.001), the blood flow in the glands remained unchanged. The vascular resistance decreased after SIN-1 in the submandibular and pancreatic glands (p < 0.001 and p < 0.05, respectively), and was slightly reduced in the parotid. The NOLA increased mean arterial blood pressure (p < 0.01) and reduced the blood flow in the submandibular and pancreatic glands (p < 0.01 and p < 0.001, respectively), but the decrease in the parotid was not significant. Vascular resistance increased after NOLA in all three glands (p < 0.05, p < 0.001 and p < 0.05). These findings suggest that basal nitric oxide production in these exocrine glands is sufficient to modulate vascular resistance. Moreover, the release of endogenous NO from the nerves and/or endothelium is probably involved in the regulation of vascular tone. The nitric oxide-dependent component of blood-flow regulation, however, seems to be less pronounced in the parotid gland.

Localization and expression of phospholipases A2 in Trimeresurus flavoviridis (habu snake) venom gland

The localization and expression profiles of phospholipases A2 (PLA2s) in Trimeresurus flavoviridis venom gland were studied by means of in situ hybridization and immunohistochemical techniques. Venom gland cells are tightly arrayed in a single layer along the inlet-like lumens in which venom proteins are stored. mRNAs for PLA2s were detected at the high level in cytoplasm. Using the immunohistochemical technique with polyclonal anti-Asp-49-PLA2 antibody, Asp-49-PLA2 and, possibly, its isozymes were detected in intracellular granules and in venom lumens. The intracellular granules containing PLA2 proteins appear to be transferred from the nucleus towards the outer membrane facing the lumen, and then to be secreted.

A novel serine-specific kinase activity associated with exocrine secretory granules

Zymogen secretion from exocrine cells involves an exocytotic process that is highly regulated by the modification of cytoplasmic components at different cellular levels. In the present studies, purified secretory granules were prepared from rabbit gastric chief cells, rat pancreatic acinar cells, and parotid glands to characterize a Mg(2+)-dependent protein kinase activity. In chief cell granules, endogenous pepsinogen, a fortuitous substrate, was phosphorylated at optimal Mg2+ and K+ concentrations of 40 and 50 mM, respectively. Adenosine 3',5'-cyclic monophosphate, Ca2+, and calmodulin had no significant effects on the kinase activity. In contrast, Mn2+ or Zn2+ inhibited the kinase activity. In addition to pepsinogen, the exogenous substrates casein, myelin basic protein, and lysine-rich histone were also phosphorylated by the granule-associated kinase. All substrates were exclusively phosphorylated on serine residues. ATP, but not GTP, served as the donor in the phosphorate transfer reaction. Casein kinase (CK) inhibitors CKI-7 and dibromoribofuransylbenzimidazole at concentrations (10 microM) that significantly inhibited CK activities in the tissue homogenate failed to inhibit the granule-associated kinase activity. The kinase activity was localized to the granule membrane and could be removed from the membrane with either 5 mM EDTA or alkaline carbonate extraction. Furthermore, protease digestion sensitivity revealed that the kinase was localized on the cytoplasmic face of the granules. Our results therefore indicate that the secretory granules of exocrine gastric chief cells, pancreatic acini, and parotid acini possess a unique serine-specific protein kinase activity. The cytoplasmic orientation of the kinase activity suggests a possible role in vesicle processing or the exocytotic process.

Carbonic anhydrase is present in human oesophageal epithelium and submucosal glands

Carbonic anhydrase (EC 4.2.1.1) activity was investigated in normal human oesophageal mucosa using the Hansson and Ridderstråle catalytic cobalt methods. The enzyme was detected in the cell membranes and nuclei and, to a lesser extent, in the cytoplasm of the epithelial cells of the mucosa giving a 'chicken wire' appearance. Activity decreased towards the lumen. Other stratified squamous epithelia--buccal mucosa, ectocervix and skin--gave a similar pattern. Acinar cells of oesophageal submucosal glands also exhibited activity for the enzyme, but the ducts did not. The formation of reaction product was prevented by acetazolamide and ethoxzolamide and by the omission of bicarbonate frm the substrate medium. Carbonic anhydrase in oesophageal squamous epithelium may be involved in the control of intra- and extracellular pH, while that in the glands is more likely to be concerned with bicarbonate secretion.

Matrix metalloproteinase matrilysin is constitutively expressed in adult human exocrine epithelium

The proteolytic activity of matrix metalloproteinases is involved in normal and disease-related remodeling processes. One member of this family, matrilysin, can degrade a wide spectrum of connective tissue proteins, suggesting that this enzyme is involved in numerous and diverse biologic processes. In fact, recent studies have shown that matrilysin is expressed in developing hair follicles and glands. Using in situ hybridization and immunohistochemistry, we examined the sites of matrilysin expression in normal and diseased adult skin. In normal mature skin, matrilysin mRNA and protein was strongly and consistently expressed in ductal cells and in some secretory cells of all eccrine and apocrine glands and was not found in any other cell type. A similar tissue distribution was also found in numerous benign inflammatory skin lesions, and prominent expression of matrilysin mRNA and protein was also found in glandular disorders such as axillary hidradenitis and sweat gland tumors. These findings indicate that matrilysin is a constitutive product of the epithelium of dermal glands and that its expression may not be related to a disease-specific or remodeling process. Because of its extensive expression in dermal glands, we assessed whether matrilysin might be produced by all exocrine glands. Indeed, we detected matrilysin mRNA and immunoreactive protein in the ductal and glandular epithelium of mammary and parotid glands, pancreas, liver, prostate, and the serous acini of peribronchial glands of the lung. Thus, our findings indicate that matrilysin is constitutively produced by exocrine epithelial cells throughout the body. Because of its broad catalytic activity, we speculate matrilysin may participate in the normal function of exocrine glands by preventing glandular obstruction.

Molecular cloning, cDNA sequence, and localization of a prohormone convertase (PC2) from the Aplysia atrial gland

Neuropeptides and peptide hormones are synthesized as part of larger precursor proteins that are processed post-translationally by subtilisin-related calcium-dependent prohormone convertases (PCs), frequently at multiple basic sites, to generate biologically active peptides. The atrial gland of Aplysia californica produces large quantities of egg-laying hormone (ELH)-related peptides, providing a unique opportunity to study prohormone processing. We have screened an Aplysia atrial gland cDNA library using a Lymnaea stagnalis PC2 probe and have isolated an Aplysia PC2-related 4.6-kb cDNA partial clone that was truncated on the 5' end. The remaining 5' atrial gland PC2 nucleotide sequence was obtained by reverse transcription/polymerase chain reaction (RT-PCR). The composite cDNA structure (5.6 kb) was deduced from sequence analysis of the RT-PCR product combined with the sequence obtained from the cDNA clone. The deduced cDNA of Aplysia atrial gland PC2 encoded a putative preproendoprotease of 653 amino acids that was evolutionarily related to other eukaryotic PC2s, and showed the strongest sequence identity with recently reported Aplysia nervous tissue PC2 sequences. In situ hybridization demonstrated extensive expression of PC2 in atrial gland secretory cells. The cDNA clone contained a relatively long 3'untranslated region (3'-UTR) of 3,632 nucleotides. Strikingly, the 3'-UTR also contained several major nucleotide repeat sequences including the microsatellite repeats, (CA)n and (TG)n, and a TA-rich region comprised largely of the triplet repeat (TTA)n. The characterized Aplysia PC2 is a candidate endoprotease that may play an important role in the processing of ELH-related precursors in the atrial gland and represents the first example of PC2 expression in exocrine tissue.