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Epidermal growth factor (EGF) is a known signaling cue essential towards the development and organoid biofabrication particularly for exocrine glands. This study developed an in vitro EGF delivery platform with Nicotiana benthamiana plant-produced EGF (P-EGF) encapsulated on hyaluronic acid/alginate (HA/Alg) hydrogel to improve the effectiveness of glandular organoid biofabrication in short-term culture systems. Primary submandibular gland epithelial cells were treated with 5 – 20 ng/mL of P-EGF and commercially available bacteria-derived EGF (B-EGF). Cell proliferation and metabolic activity were measured by MTT and luciferase-based ATP assays. P-EGF and B-EGF 5 – 20 ng/mL promoted glandular epithelial cell proliferation during 6 culture days on a comparable fashion. Organoid forming efficiency and cellular viability, ATP-dependent activity and expansion were evaluated using two EGF delivery systems, HA/Alg-based encapsulation and media supplementation. Phosphate buffered saline (PBS) was used as a control vehicle. Epithelial organoids fabricated from PBS-, B-EGF-, and P-EGF-encapsulated hydrogels were characterized genotypically, phenotypically and by functional assays. P-EGF-encapsulated hydrogel enhanced organoid formation efficiency and cellular viability and metabolism relative to P-EGF supplementation. At culture day 3, epithelial organoids developed from P-EGF-encapsulated HA/Alg platform contained functional cell clusters expressing specific glandular epithelial markers such as exocrine pro-acinar (AQP5, NKCC1, CHRM1, CHRM3, Mist1), ductal (K18, Krt19), and myoepithelial (α-SMA, Acta2), and possessed a high mitotic activity (38–62% Ki67 cells) with a large epithelial progenitor population (∼70% K14 cells). The P-EGF encapsulation strikingly upregulated the expression of pro-acinar AQP5 cells through culture time when compared to others (B-EGF, PBS). Thus, the utilization of Nicotiana benthamiana in molecular farming can produce EGF biologicals amenable to encapsulation in HA/Alg-based in vitro platforms, which can effectively and promptly induce the biofabrication of exocrine gland organoids.

The lacrimal gland is of central interest in ophthalmology both as the source of the aqueous component of tear fluid and as the site of autoimmune pathology in the context of Sjogren's syndrome (SjS). To provide a foundational description of mouse lacrimal gland cell types and their patterns of gene expression, we have analyzed single-cell transcriptomes from wild-type (Balb/c) mice and from two genetically based SjS models, MRL/lpr and NOD (nonobese diabetic).H2b, and defined the localization of multiple cell-type-specific protein and mRNA markers. This analysis has uncovered a previously undescribed cell type, Car6+ cells, which are located at the junction of the acini and the connecting ducts. More than a dozen secreted polypeptides that are likely to be components of tear fluid are expressed by acinar cells and show pronounced sex differences in expression. Additional examples of gene expression heterogeneity within a single cell type were identified, including a gradient of Claudin4 along the length of the ductal system and cell-to-cell heterogeneity in transcription factor expression within acinar and myoepithelial cells. The patterns of expression of channels, transporters, and pumps in acinar, Car6+, and ductal cells make strong predictions regarding the mechanisms of water and electrolyte secretion. In MRL/lpr and NOD.H2b lacrimal glands, distinctive changes in parenchymal gene expression and in immune cell subsets reveal widespread interferon responses, a T cell-dominated infiltrate in the MRL/lpr model, and a mixed B cell and T cell infiltrate in the NOD.H2b model. [ABSTRACT FROM AUTHOR]

Simple Summary: Camponotus japonicus is a soil-dwelling ant species that is widespread in China and Southeast Asia. A mature nest consists of minor workers, major workers, gynes, males, and a queen. The original workers, which are raised by the queen during the early nest-building stage, are smaller than other castes. The Dufour's and venom glands are two important glands associated with the sting apparatus in female castes. Their secretions play significant roles in defense, reproduction, communication, and foraging in the social life of ants. However, the exact nature of their secretions and whether there are differences among castes remain unknown. In this study, we analyzed the secretions of these two glands using gas chromatography–mass spectrometry with two sample processing methods (hexane solution and solid-phase microextraction). The main secretion of the Dufour's gland is n-undecane, whose proportion significantly varies among castes. The main secretions of the venom gland are formic acid and n-undecane, and their proportions show obvious differences among castes. This study provides basic information to further understand the function of these two glands in the social life of ants. The Dufour's and venom glands are the most developed glands connected to the female reproductive organs, playing important roles in defense, foraging, information exchange, and reproduction in ants. The main chemical secretions of these glands vary among species and even among castes of the same species. In this study, we analyzed the chemical components of the Dufour's and venom glands in different castes of Camponotus japonicus (original worker, minor worker, major worker, gyne, and queen) using gas chromatography–mass spectrometry (GC–MS) with two sample processing methods (hexane solution and solid-phase microextraction). The secretion of the Dufour's gland is characterized by a high ratio of alkanes, with n-undecane being the dominant secretion in all castes except the original workers. The venom gland's secretion mainly includes alkanes, acids, ketones, and alcohols, with formic acid and n-undecane being the dominant components. Additionally, the chemical composition and proportion of the main components vary significantly among castes, which may be closely related to the division of labor in their social life. This study provides basic information to further understand the function of these two glands in the social life of ants. [ABSTRACT FROM AUTHOR]

The lacrimal gland (LG) secretes aqueous tears. Previous studies have provided insights into the cell lineage relationships during tissue morphogenesis. However, little is known about the cell types composing the adult LG and their progenitors. Using scRNAseq, we established the first comprehensive cell atlas of the adult mouse LG to investigate the cell hierarchy, its secretory repertoire, and the sex differences. Our analysis uncovered the complexity of the stromal landscape. Epithelium subclustering revealed myoepithelial cells, acinar subsets, and two novel acinar subpopulations: Tfrchi and Car6hi cells. The ductal compartment contained Wfdc2+ multilayered ducts and an Ltf+ cluster formed by luminal and intercalated duct cells. Kit+ progenitors were identified as: Krt14+ basal ductal cells, Aldh1a1+ cells of Ltf+ ducts, and Sox10+ cells of the Car6hi acinar and Ltf+ epithelial clusters. Lineage tracing experiments revealed that the Sox10+ adult populations contribute to the myoepithelial, acinar, and ductal lineages. Using scRNAseq data, we found that the postnatally developing LG epithelium harbored key features of putative adult progenitors. Finally, we showed that acinar cells produce most of the sex-biased lipocalins and secretoglobins detected in mouse tears. Our study provides a wealth of new data on LG maintenance and identifies the cellular origin of sex-biased tear components. [ABSTRACT FROM AUTHOR]

Ants are eusocial insects with a complex adaptive foraging system regulated by trail pheromones. This review summarizes ants' pheromone-producing exocrine glands, the chemical composition of ant trail pheromones, and their function and functional characteristics. Glands that secrete trail pheromones include Dufour's gland, poison glands, Pavan's gland and the pygidial gland. Trail pheromones are mostly volatile substances with complex and diverse structures, including hydrocarbons, alkaloids, organic acids, aldehydes, alcohols, ketones and esters. Their functions include orientation and recruitment. Prospects for the future application of trail pheromones in pest ant management are discussed. [ABSTRACT FROM AUTHOR]

Multiple pathologies and non-pathological factors can disrupt the function of the non-regenerative human salivary gland including cancer and cancer therapeutics, autoimmune diseases, infections, pharmaceutical side effects, and traumatic injury. Despite the wide range of pathologies, no therapeutic or regenerative approaches exist to address salivary gland loss, likely due to significant gaps in our understanding of salivary gland development. Moreover, identifying the tissue of origin when diagnosing salivary carcinomas requires an understanding of human fetal development. Using computational tools, we identify developmental branchpoints, a novel stem cell-like population, and key signaling pathways in the human developing salivary glands by analyzing our human fetal single-cell sequencing data. Trajectory and transcriptional analysis suggest that the earliest progenitors yield excretory duct and myoepithelial cells and a transitional population that will yield later ductal cell types. Importantly, this single-cell analysis revealed a previously undescribed population of stem cell-like cells that are derived from SD and expresses high levels of genes associated with stem cell-like function. We have observed these rare cells, not in a single niche location but dispersed within the developing duct at later developmental stages. Our studies introduce new human-specific developmental paradigms for the salivary gland and lay the groundwork for the development of translational human therapeutics.

The Dufour’s and venom glands are the most developed glands connected to the female reproductive organs, playing important roles in defense, foraging, information exchange, and reproduction in ants. The main chemical secretions of these glands vary among species and even among castes of the same species. In this study, we analyzed the chemical components of the Dufour’s and venom glands in different castes of Camponotus japonicus (original worker, minor worker, major worker, gyne, and queen) using gas chromatography–mass spectrometry (GC–MS) with two sample processing methods (hexane solution and solid-phase microextraction). The secretion of the Dufour’s gland is characterized by a high ratio of alkanes, with n-undecane being the dominant secretion in all castes except the original workers. The venom gland’s secretion mainly includes alkanes, acids, ketones, and alcohols, with formic acid and n-undecane being the dominant components. Additionally, the chemical composition and proportion of the main components vary significantly among castes, which may be closely related to the division of labor in their social life. This study provides basic information to further understand the function of these two glands in the social life of ants.

The lacrimal gland (LG) secretes aqueous tears. Previous studies have provided insights into the cell lineage relationships during tissue morphogenesis. However, little is known about the cell types composing the adult LG and their progenitors. Using scRNAseq, we established the first comprehensive cell atlas of the adult mouse LG to investigate the cell hierarchy, its secretory repertoire, and the sex differences. Our analysis uncovered the complexity of the stromal landscape. Epithelium subclustering revealed myoepithelial cells, acinar subsets, and two novel acinar subpopulations: Tfrchi and Car6hi cells. The ductal compartment contained Wfdc2+ multilayered ducts and an Ltf+ cluster formed by luminal and intercalated duct cells. Kit+ progenitors were identified as: Krt14+ basal ductal cells, Aldh1a1+ cells of Ltf+ ducts, and Sox10+ cells of the Car6hi acinar and Ltf+ epithelial clusters. Lineage tracing experiments revealed that the Sox10+ adult populations contribute to the myoepithelial, acinar, and ductal lineages. Using scRNAseq data, we found that the postnatally developing LG epithelium harbored key features of putative adult progenitors. Finally, we showed that acinar cells produce most of the sex-biased lipocalins and secretoglobins detected in mouse tears. Our study provides a wealth of new data on LG maintenance and identifies the cellular origin of sex-biased tear components.

To attract a mate, females of most moth species synthesize and emit sex pheromone from a specific gland in a behavior termed "calling". In a broad temporal sense, calling behavior and pheromone synthesis are synchronized through the overlap of their circadian rhythms. However, the limited amount of pheromone a female produces each day must be managed so that pheromone is emitted at a sufficient (to attract males) mass emission rate (MER) over the entire calling period, typically many hours. We are studying pheromone synthesis and emission in the moth Chloridea (formerly Heliothis) virescens (family Noctuidae). One way that female C. virescens manage pheromone over their calling period is by calling intermittently; the period between calling bouts allows females to replenish pheromone, and resume calling at high MERs. However, militating against replenishment is loss of pheromone through putative catabolism. In this paper, we examined three aspects pertaining to pheromone MER in C. virescens: (i) the effect of adult feeding on calling behavior, (ii) the effect of certain behavioral/physical parameters on MER, and (iii) the relative loss (putative catabolism) of pheromone in retracted (non-calling) and everted (calling) glands. We found that (i) adult feeding increases calling duration, consistent with the known concomitant increase in pheromone production, (ii) various physical factors relating to the gland, including degree of eversion (surface area), orientation to airstream, and air velocity over the gland influence MER, and (iii) putative catabolism occurs in both retracted and everted glands, but substantially less pheromone is lost in the everted gland primarily because of the high MER when the gland is first everted. Together, these data demonstrate that, over the calling period, the efficient use of pheromone for emission by female C. virescens is dependent on the interaction among synthesis, storage, catabolism, and calling behavior. [ABSTRACT FROM AUTHOR]

Salivary fluid secretion involves an intricate choreography of membrane transporters to result in the trans-epithelial movement of NaCl and water into the acinus lumen. Current models are largely based on experimental observations in enzymatically isolated cells where the Ca2+ signal invariably propagates globally and thus appears ideally suited to activate spatially separated Cl and K channels, present on the apical and basolateral plasma membrane, respectively. We monitored Ca2+ signals and salivary secretion in live mice expressing GCamp6F, following stimulation of the nerves innervating the submandibular gland. Consistent with in vitro studies, Ca2+ signals were initiated in the apical endoplasmic reticulum. In marked contrast to in vitro data, highly localized trains of Ca2+ transients that failed to fully propagate from the apical region were observed. Following stimuli optimum for secretion, large apical-basal gradients were elicited. A new mathematical model, incorporating these data was constructed to probe how salivary secretion can be optimally stimulated by apical Ca2+ signals.

Most species of moths use a female-produced sex pheromone to bring mates together. Typically, sex pheromone is synthesized in a specialized gland and released during the behavior of "calling", in which the ovipositor and gland are extruded, allowing pheromone to evaporate. Although there has been much study on how a gland makes specific pheromone components, we know relatively little about how it actually functions with regard to synthesis, storage and release. In this paper, we investigated three aspects of gland function in the noctuid moth Chloridea virescens (Fabricius): (i) whether translocation of pheromone from site of synthesis to release is dependent on calling or ovipositor movement, (ii) whether pheromone synthesis rate limits release and (iii) how intermittent calling (observed in this and other species) might affect the dynamics of release rate. Firstly, by manipulating the gland to simulate calling (extruded) or non-calling (retracted), we showed that pheromone translocation occurred regardless of whether the gland was retracted or extruded. Secondly, by manipulating pheromone production, we found that females that produced more pheromone had higher release rates. It was especially noticeable that females had a higher release rate at the start of calling, which dropped rapidly and leveled off over time. Together, these data suggest that intermittent calling in C. virescens (and other species) may function to allow females to replenish pheromone stores on the gland surface between calling bouts, so that brief, high release rates occur at the start of a calling bout; thus, potentially increasing a female's chances of attracting a mate. [ABSTRACT FROM AUTHOR]

Formicine ants in distress spray alarm pheromone which typically recruits nestmates for help. Studying the western carpenter ant, Camponotus modoc Wheeler (Hymenoptera: Formicidae), our objectives were to (1) determine the exocrine glands that contain alarm recruitment pheromone, (2) identify the key alarm recruitment pheromone components, and (3) ascertain the pheromone components that are discharged by distressed ants. In Y‐tube olfactometer experiments, extracts of poison glands, but not of Dufour's glands, elicited anemotactic responses from worker ants. Gas chromatographic‐mass spectrometric analyses of poison gland extracts revealed the presence of (1) aliphatic alkanes (undecane, tridecane, pentadecane, heptadecane), (2) aliphatic alkenes [(Z)‐7‐pentadecene, (Z)‐7‐ and (Z)‐8‐heptadecene], (3) two acids (formic, benzoic), and (4) other oxygenated compounds (hexadecan‐1‐ol, hexadecyl formate, hexadecyl acetate). Testing the responses of worker ants in Y‐tube olfactometers to complete and partial synthetic blends of these compounds revealed that the acids and the alkanes are essential alarm pheromone components. In two‐choice arena bioassays, micro‐locations treated with synthetic alarm pheromone recruited worker ants. Acids and alkanes were abundant in the poison gland and the Dufour's gland, respectively, suggesting that the alarm pheromone components originate from both glands. Moreover, alarm pheromone sprays of ants differed in that all sprays contained formic acid but only some also contained alkanes, implying that ants can independently discharge the content of either one or both glands in accordance with the type of distress incident they experience. [ABSTRACT FROM AUTHOR]

Trail pheromones deposited by ants lead nestmates to food sources. Based on previous evidence that the trail pheromone of the carpenter ant Camponotus modoc originates from the hindgut, our objective in this study was to identify the key component(s) of the pheromone. We collected C. modoc colonies from conifer forests and maintained them in an outdoor enclosure near our laboratory for chemical analyses and behavioral experiments. In gas chromatographic-electroantennographic detection and gas chromatography-mass spectrometric analyses of worker ant hindgut extracts, we identified five candidate components: 2,4-dimethylhexanoic acid, 2,4-dimethyl-5-hexanolide, pentadecane, dodecanoic acid and 3,4-dihydro-8-hydroxy-3,5,7-trimethylisocoumarin. In a series of trail-following experiments, ants followed trails of synthetic 2,4-dimethyl-5-hexanolide, a blend of the five compounds, and hindgut extract over similar distances, indicating that the hexanolide accounted for the entire behavioral activity of the hindgut extract. The hexanolide not only mediated orientation of C. modoc foragers on trails, it also attracted them over distance, indicating a dual function. Further analyses and bioassays with racemic and stereoselectively synthesized hexanolides revealed that the ants produce, and respond to, the (2S,4R,5S)-stereoisomer. The same stereoisomer is a trail pheromone component in several Camponotus congeners, indicating significant overlap in their respective trail pheromone communication systems. [ABSTRACT FROM AUTHOR]

Abstract Background The hypopharyngeal gland of worker bees contributes to the production of the royal jelly fed to queens and larvae. The gland consists of thousands of two-cell units that are composed of a secretory cell and a duct cell and that are arranged in sets of about 12 around a long collecting duct. Results By fluorescent staining, we have examined the morphogenesis of the hypopharyngeal gland during pupal life, from a saccule lined by a pseudostratified epithelium to the elaborate organ of adult worker bees. The hypopharyngeal gland develops as follows. (1) Cell proliferation occurs during the first day of pupal life in the hypopharyngeal gland primordium. (2) Subsequently, the epithelium becomes organized into rosette-like units of three cells. Two of these will become the secretory cell and the duct cell of the adult secretory units; the third cell contributes only temporarily to the development of the secretory units and is eliminated by apoptosis in the second half of pupal life. (3) The three-cell units of flask-shaped cells undergo complex changes in cell morphology. Thus, by mid-pupal stage, the gland is structurally similar to the adult hypopharyngeal gland. (4) Concomitantly, the prospective secretory cell attains its characteristic subcellular organization by the invagination of a small patch of apical membrane domain, its extension to a tube of about 100 μm in length (termed a canaliculus), and the expansion of the tube to a diameter of about 3 μm. (6) Finally, the canaliculus-associated F-actin system becomes reorganized into rings of bundled actin filaments that are positioned at regular distances along the membrane tube. Conclusions The morphogenesis of the secretory units in the hypopharyngeal gland of the worker bee seems to be based on a developmental program that is conserved, with slight modification, among insects for the production of dermal glands. Elaboration of the secretory cell as a unicellular seamless epithelial tube occurs by invagination of the apical membrane, its extension likely by targeted exocytosis and its expansion, and finally the reorganisation of the membrane-associated F-actin system. Our work is fundamental for future studies of environmental effects on hypopharyngeal gland morphology and development.

As descendants of social cockroaches, termites have an intriguing biology that makes them highly suitable study subjects in a wide variety of fields, such as eusocial evolution, ageing mechanisms, wood decomposition, ecosystem engineering, and pest management. This special section presents four studies ranging from the role of chemical compounds in foraging behaviour and food digestion to genetics and physiology of reproduction. Taken together, these studies offer new insights and ample suggestions for future work on these fascinating insects. [ABSTRACT FROM AUTHOR]

Summary: Prolyl endopeptidase (PREP) is a post-proline cleaving enzyme. It is involved in the regulation of multiple inositol polyphosphate phosphatase activity implicated in the pathway of inositol 1,4,5-trisphosphate, resulting in the modulation of cytosolic Ca2+ levels. Besides its peptidase activity, PREP was identified as a binding partner of tubulin, suggesting that it may participate in microtubule-associate processes. In this paper, we evaluated the expression of PREP mRNA and protein by polymerase chain reaction and western blot analyses and its co-localization with tubulin by immunofluorescence in adult mouse seminal vesicles. We showed that both proteins are cytoplasmic: tubulin is localized at the apical half part of the cell, while PREP has a more diffuse localization, showing a prominent distribution at the apical cytoplasm. These findings support our hypothesis of a specific role for PREP in cytoskeletal rearrangement that occurs during the exocytosis of secretory vesicles, and in particular its association with tubulin filaments. Moreover, it may regulate Ca2+ levels, and promote the final step of vesicular exocytosis, namely the fusion of the vesicles with the plasma membrane. These results strongly suggest that there is a pivotal role for PREP in vesicle exocytosis, as well as in the physiology of mouse seminal vesicles. [ABSTRACT FROM AUTHOR]

Termites are important contributors to ecosystem functioning. They are highly abundant in tropical and sub-tropical habitats, and represent an important resource for a wide range of predators. Their evolutionary success is driven largely by a life in populous colonies with a complex communication system controlled by a rich set of exocrine glands whose secretions are involved in many aspects of termite life. As many as 20 different exocrine organs are known to occur in termites. Among them, the labral gland has been largely understudied. Here we examine the structure of the labral gland in workers of 28 species and imagoes of 33 species across all termite taxa, and in the Cryptocercus wood roach. The labral gland is present in all species, and comprises two secretory regions located on the ventral side of the labrum and the dorso-apical part of the hypopharynx, respectively. The epithelium of the gland consists of class 1 secretory cells with an abundance of smooth endoplasmic reticulum, and long microvilli with a channel inside, which releases secretion through a modified cuticle. Our observations suggest that the labral gland is involved in defensive communication after encounter with a non-nestmate. [ABSTRACT FROM AUTHOR]

The mandibular gland is an important exocrine gland connected to the mandibles. In ants, it plays a crucial role in alarm communication and reproduction. While the overall morphology of the mandibular gland does not vary much between ant species, significant differences exist in the ultrastructural characteristics and gland size in some reported cases. However, there have been few systematic comparative studies on this subject. In this paper, we conducted microscopic observations to analyze the morphological and ultrastructural similarities and differences of the mandibular gland in different castes of Camponotus japonicus. Our findings revealed that the mandibular glands of males were significantly larger than those of females. In terms of relative size, within the female castes the mandibular glands of minor workers were the largest. Additionally, our observations of the ultrastructure showed that secretory substances were most abundant in queens. All female castes and males showed the presence of crystalline structures in the secretory cells. The content of these biocrystals decreased from minor workers to major workers, queens, and males. In males, however, crystalline structures were rare and the most abundant substances are droplet-like secretions. The differences in morphology and ultrastructure between different castes suggest that the function of the mandibular gland varies among castes. In conclusion, our study provides insights into the morphological and ultrastructural characteristics of the mandibular gland in different castes of C. japonicus. Further research is needed to fully understand the specific functions and mechanisms of this gland in ants. • Morphology and ultrastructure of the mandibular gland in the ant Camponotus japonicus were examined. • The caste differentiation of the mandibular gland ultrastructure among castes in C. japonicus was reported. • Crystalline secretions "biocrystals" not seen previously in ants' glands, are introduced. [ABSTRACT FROM AUTHOR]

The elimination of toxins via a venom gland by some ant species is a component of a larger mechanism for capturing prey and defense. The present study describes the morphology and histochemistry of the venom apparatus of different castes of the ant Ectatomma vizottoi Almeida, 1987. Morphologically, the venom apparatus of queens, gynes and workers of E. vizottoi are similar and composed of the sting apparatus and three distinct portions: two secretory portions (convoluted gland and secretory filament), and a storage portion (reservoir) - a hollow sting apparatus covered in the terminal portion of the reservoir by a sclerotized cuticle. The venom gland of E. vizottoi is longer in queens and gynes than in workers. Furthermore, the epithelium of the convoluted gland is taller in the glands of queens and gynes than in workers, which may be indicative of greater toxin synthesis, or may be related to different body sizes of the castes. The morphology and histology of the venom apparatus reflect those of a generalist, while the histochemical tests indicated that this structure has the same chemical content of lipids, proteins and polysaccharides among queens, gynes, and workers. Images obtained by confocal microscopy and scanning electronic microscopy reveal a muscle layer surrounding the reservoir that is interlaced with secretory filaments, which fixes, in a manner, the filaments in place. This musculature serves to eject stored venom, which likely leads to greater success in defense or foraging.

Three species of Hyperophora Brunner von Wattenwyl have a tubercle on the second abdominal tergite with different external appearance among species. We predicted that the tubercles are a glandular structure for their morphology and anatomical position. In H. major Brunner von Wattenwyl and H. brasiliensis Brunner von Wattenwyl the tubercle is low and broad, whereas in H. minor Brunner von Wattenwyl it is high. In all species the tubercle does not have an external opening, but it has many chemosensory sensilla, evidenced by long setae with an internal cavity with a membrane-like content. The cuticular surface of the tubercle has many pores with ∼1–2 μm in diameter scattered among the sensilla. On the inner surface of the tubercular region occur epidermal gland cells, evidenced by a mass of large globular cells with an irregular and well-developed nucleus with predominance of decondensed chromatin and a large nucleolus. The cytoplasm of these cells is rich in small clear vacuoles, and has an end apparatus, a feature of epidermal gland cells of class III. Each gland cell has a conducting canal that opens into a cuticular pore. These results support the hypothesis that the tubercles are indeed of glandular nature. [ABSTRACT FROM AUTHOR]

RNA-Seq was used to better understand the molecular nature of the biological differences among the three major exocrine salivary glands in mammals. Transcriptional profiling found that the adult murine parotid, submandibular, and sublingual salivary glands express greater than 14,300 protein-coding genes, and nearly 2,000 of these genes were differentially expressed. Principle component analysis of the differentially expressed genes revealed three distinct clusters according to gland type. The three salivary gland transcriptomes were dominated by a relatively few number of highly expressed genes (6.3%) that accounted for more than 90% of transcriptional output. Of the 912 transcription factors expressed in the major salivary glands, greater than 90% of them were detected in all three glands, while expression for ~2% of them was enriched in an individual gland. Expression of these unique transcription factors correlated with sublingual and parotid specific subsets of both highly expressed and differentially expressed genes. Gene ontology analyses revealed that the highly expressed genes common to all glands were associated with global functions, while many of the genes expressed in a single gland play a major role in the function of that gland. In summary, transcriptional profiling of the three murine major salivary glands identified a limited number of highly expressed genes, differentially expressed genes, and unique transcription factors that represent the transcriptional signatures underlying gland-specific biological properties. [ABSTRACT FROM AUTHOR]

The evolutionary success of termites has been driven largely by a complex communication system operated by a rich set of exocrine glands. As many as 20 different exocrine organs are known in termites. While some of these organs are relatively well known, only anecdotal observations exist for others. One of the exocrine organs that has received negligible attention so far is the labral gland. In this study, we examined the structure and ultrastructure of the labrum in soldiers of 28 termite species. We confirm that the labral gland is present in all termite species, and comprises two secretory regions located on the ventral side of the labrum and the dorso-apical part of the hypopharynx. The labrum of Neoisoptera has a hyaline tip, which was secondarily lost in Nasutitermitinae, Microcerotermes and species with snapping soldiers. The epithelium of the gland generally consists of class 1 secretory cells, with an addition of class 3 secretory cells in some species. A common feature of the secretory cells is the abundance of smooth endoplasmic reticulum, an organelle known to produce lipidic and often volatile secretions. Our observations suggest that the labral gland is involved in communication rather than defence as previously suggested. Our study is the first to provide a comprehensive picture of the structure of the labral gland in soldiers across all termite taxa. [ABSTRACT FROM AUTHOR]