Detection of Hepatoid Glands and Distinctive Features of the Hepatoid Acinus

In the 1920s–1930s, skin glands of a new type, hepatoid glands, were described in 13 mammal species (Rodentia, Canidae, and Bovidae). The hepatoid glands resemble sebaceous glands in their morphology, bur radically differ from them in specific structure of the acinus and another type of secretion. Later, these data either could not be confirmed or were considered insignificant and the hepatoid glands were described as modified sebaceous glands, glands with uncertain function, or modifications of epidermis. Based on the studies of various hepatoid glands in 22 species of Carniviora and Artiodactyla, the authors described in detail the characteristic features of the hepatoid acinus, which allow a precise discrimination of hepatoid and sebaceous glands. Extracellular secretory canaliculi have been described in the hepatoid glands, as well as the richness of hepatoid glands in protein, distribution of hydrophobic lipids in certain hepatoid glands, and formation of excretory ducts and cysts. The hepatoid glands are a source of great amounts of protein secreted in the merocrine way; the secretory substance of some of these glands has a strong odor.     

Once More about Hepatoid Circumanal Glands of Dogs; History of Their Discovery and Causes of Revision of Their Structure and Function

In the skin surrounding the anus in dogs and other Canidae, there is a glandular sheet consisting of strongly developed hepatoid glands, as well as single apocrine glands and a certain number of sebaceous glands, which are much smaller and occur less frequently than the hepatoid glands. All three circumanal glands have excretory ducts connecting with the hair bags (hair funnels). The hepatoid glands of some Canidae and Bovidae were extensively studied in the 1920s–1930s, but from the beginning of the 1950s until the present, as a result of the often repeated mistake passing from one book to another, old information about the hepatoid glands was fully lost, while the new information does not answer the question about the function of this complex and well developed structure. We were successful in repeating the data of the discoverers of the hepatoid glands and proved that these glands are exocrine and that their cells excrete protein to intercellular channels and then to ducts and hair funnels. According to the published data, the odor of the secretory substance of the circumanal hepatoid glands is essential for communication in wolves and dogs.     

The morphogenesis of mammalian cutaneous glands in evolutionary perspective

The morphogenesis of mammalian cutaneous glands is considered based on the analysis of the literature and our own original data with the focus on the issues of gland polymorphism and specific features in postnatal development (from the case study of circumanal hepatoid glands of newborn domestic dogs), including the features reflecting the evolutionary relationships of various types of cutaneous glands. The hepatoid glands are a component of the glandular complex of the hair follicle, which also includes sebaceous and sweat glands; have a specific structure; and produce protein secretion by a merocrine pathway. Characteristic of these glands are wide polymorphism, sex- and age-related differences in the degree of development, occurrence in only a few phylogenetically related mammalian taxa (even-toed ungulates and carnivores); and a signaling type of their secretion. The data support the “generative concept,” relying on the idea of a separate and independent origination of diverse derivatives of the external integuments.     

Contradictions in Modern Data on the Structure and Function of Dog Hepatoid Circumanal Glands1

Since the 1950s, an erroneous viewpoint has gained a foothold in the special and reference literature that dog hepatoid circumanal glands have an abortive nature, lack efferent ducts, and show no signs of secretory activity. Nevertheless, most modern researchers indicate that these glands are actively functioning structures differentiated to exercise some function according to their histological pattern; however, no one has managed to define this function. The latest international publication (Atoji et al., 1998) considers dog circumanal hepatoid glands as a circumanal body similar to epidermis rather than glands. We discuss strong and weak points of the data on dog hepatoid circumanal glands published in 1950s–1990s in comparison with those obtained in our purposeful long-term investigation of various hepatoid glands. We strongly disagree with the viewpoint of Atoji et al. (1998); hepatoid circumanal glands of dog and other canids should be considered as odor glands, their abundant protein secretion covers the skin surface in the circumanal region, it is preserved on fecal marks, and its smell is perceived during mutual nosing of the anal region.     

The histological and histochemical characteristics of the hepatoid circumanal glands in the dog: the features of similarity and difference with the skin glands of other types

Three types of skin glands, the derivatives of the outer root sheath of the hair follicle, have been compared, which are represented by hepatoid, sebaceous and apocrine sweat glands. There are three characteristic properties inherent to hepatoid glands, existence of a network of intercellular secretory tubules, lysis of some secretory cells during the duct formation which is not the fatty transformation and cyst formation.     

Microstructure of skin derivatives as a reflection of phylogenesis of vertebrates

The possibility of using separate signs of microstructure of skin derivatives to understand phylogenesis processes at various hierarchical levels on the example of elasmoid scale of bony fish, feathers of Paleognathae birds, hepatoid glands, and mammal hair was demonstrated and discussed. It was shown that (1) the presence of toothed sclerite growths on the surface of the elasmoid scale of bony fish provided with a central canal can serve as a proof of the evolutional relation of placoid and elasmoid scales; (2) particularities of the microstructure of feathers of Paleognathae birds accord with the branching of their phylogenetic tree; (3) the development of hepatoid glands suggests a phylogenetic relatedness of ancestor forms of cavicorns, Canidae, and Felidae; (4) the subtle construction of horse hair shows the succession of the ancient E. lenensis and northern aborigine breeds of the domestic horse, the direction of the historical process of horse domestication and adaptation of these animals to environmental conditions; (5) similarities in the microstructure of hair of the giant and red panda and bears indicate their evolutional links with Ursidae rather than raccoons.     

Hepatoid adenocarcinoma of the stomach – a different histology for not so different gastric adenocarcinoma: a case report

Hepatoid adenocarcinoma is an extrahepatic tumor characterized by morphological similarities to hepatocellular carcinoma. Hepatoid adenocarcinoma of the stomach is a cancer with an extremely poor prognosis with few cases reported. Here, we describe a 75-year-old Spanish man referred to our hospital with a history of abdominal pain, general fatigue, anorexia and sickness. Initial study revealed anemia, and computed tomography scan and abdominal ultrasonography showed multiple metastases to the liver with hepatocellular carcinoma characteristics in a liver with no cirrhotic change. Further study included a serum level of alpha-fetoprotein (AFP), which resulted markedly elevated, and a conclusive esophagogastroduodenoscopy describing an elevated tumour growing through the cardia and gastroesophageal junction with foci of necrosis and haemorrhage. Gastric biopsies of the tumor revealed poorly differenciated adenocarcinoma, with hepatoid differentiation. After a diagnosis of AFP-producing hepatoid adenocarcinoma of the stomach with multiple liver metastases was made, pallitive total gastrectomy, without liver resection, was performed. Patient recovered well after surgery, and entered into a palliative systemich chemotherapy protocol. Although this illness is recognized as having poor prognosis, the patient remains alive 8 months after the operation. Accurate diagnosis of hepatoid adenocarcinoma of the stomach is important, and should be suspected under certain circumstances. We describe this rare case of hepatoid adenocarcinoma of the stomach, and review the literature concerning the clinicopathological aspects.     

Change in Size Distribution of Active Polyribosomes Associated with Puff Induction in Drosophila melanogaster Salivary Glands

The polytene cells of Drosophila melanogaster larvae are ideally suited for the study of gene information flow during differentiation, in that gene derepression is visualized in the form of chromosomal modifications called puffs. One special group of temperature-sensitive puffs can be experimentally induced within 5 min after transfer of salivary glands from 24–37^° C. Glands at 37^° C also begin synthesizing several new polypeptides which are of higher molecular weight than the prominent polypeptides being synthesized in glands at 24^° C [1].
The present study demonstrates that there is also a shift toward the utilization of heavier or more rapidly sedimenting polyribosomes for protein synthesis in glands transferred from 24–37° C. As a result of such studies it is reasonable to assume that the polyribosome redistribution after a heat shock results from the translation of larger mRNA molecules synthesized by the temperature-sensitive loci. Further studies are suggested to describe the role of heat-induced gene activity in maintaining homeostasis, as well as the manner by which such activity is induced, in cells subjected to dramatic temperature fluctuations.     

Dissection of the 16S rRNA binding site for ribosomal protein S4

The ribosomal protein S4 from Escherichia coli is essential for initiation of assembly of 30S ribosomal subunits. We have undertaken the identification of specific features required in the 16S rRNA for S4 recognition by synthesizing mutants bearing deletions within a 460 nucleotide region which contains the minimum S4 binding site. We made a set of large nested deletions in a subdomain of the molecule, as well as individual deletions of nine hairpins, and used a nitrocellulose filter binding assay to calculate association constants. Some small hairpins can be eliminated with only minor effects on S4 recognition, while three hairpins scattered throughout the domain (76-90, 376-389 and 456-476) are essential for specific interaction. The loop sequence of hairpin 456-476 is important for S4 binding, and may be directly recognized by the protein. Some of the essential features are in phylogenetically variable regions; consistent with this, Mycoplasma capricolum rRNA is only weakly recognized by S4, and no specific binding to Xenopus laevis rRNA can be detected.     

Localization of Type-2 Angiotensin II Receptor in Adrenal Gland

The localization of the type-2 angiotensin II receptor (AT2) in the adrenal glands of rats, guinea pigs, bovines, and humans was examined at the mRNA and protein levels. PCR products for AT2 were detected in the adrenal cortices and adrenal medullae of all the mammals examined with an RT-PCR technique. Three different anti-AT2 antibodies (Abs), whose specificity was confirmed in our hands, recognized a 50-kDa protein in the adrenal glands of the four mammals, and this recognition was abolished by the preabsorption of an Ab with an antigen. Immunoblotting and immunohistochemistry revealed that the 50-kDa protein was expressed consistently and variably in the adrenal cortices and medullae of various mammals, respectively. We conclude that the 50-kDa AT2 is consistently expressed in the adrenal cortex in a wide variety of mammals. (J Histochem Cytochem 58:585–593, 2010)     

Na+-Glucose Cotransporter SGLT1 Protein in Salivary Glands: Potential Involvement in the Diabetes-Induced Decrease in Salivary Flow

Oral health complications in diabetes include decreased salivary secretion. The SLC5A1 gene encodes the Na⁺-glucose cotransporter SGLT1 protein, which not only transports glucose, but also acts as a water channel. Since SLC5A1 expression is altered in kidneys of diabetic subjects, we hypothesize that it could also be altered in salivary glands, contributing to diabetic dysfunction. The present study shows a diabetes-induced decrease (p < 0.001) in salivary secretion, which was accompanied by enhanced (p < 0.05) SGLT1 mRNA expression in parotid (50%) and submandibular (30%) glands. Immunohistochemical analysis of parotid gland of diabetic rats revealed that SGLT1 protein expression increased in the luminal membrane of ductal cells, which can stimulate water reabsorption from primary saliva. Furthermore, SGLT1 protein was reduced in myoepithelial cells of the parotid from diabetic animals, and that, by reducing cellular contractile activity, might also be related to reduced salivary flux. Six-day insulin-treated diabetic rats reversed all alterations. In conclusion, diabetes increases SLC5A1 gene expression in salivary glands, increasing the SGLT1 protein content in the luminal membrane of ductal cells, which, by increasing water reabsorption, might explain the diabetes-induced decrease in salivary secretion.     

Effect of primer pheromones and pollen diet on the food producing glands of worker honey bees (Apis mellifera L.)

Cooperative brood care is highly developed in the honey bee such that workers called nurses use their hypopharyngeal and mandibular glands to biosynthesize proteinaceous secretions that are progressively provisioned to larvae. The role that honey bee primer pheromones play in the functional physiology of food producing glands was examined. The combined and separate effects of queen mandibular pheromone (QMP) and brood pheromone (BP) on amount of protein extractable from hypopharyngeal and mandibular glands of workers reared for 12 days with and without pollen diets was measured. In rearing environments with a pollen diet, BP, and QMP + BP pheromone treatments significantly increased extractable protein from both glands. Bees reared with QMP + pollen had amounts of protein extractable from both glands that were not significantly different from control bees (no pheromones, no pollen). Pollen in the diet alone significantly increased amounts of protein extractable from glands versus control. In rearing environments without pollen, QMP + BP had a synergizing effect on amount of protein in both glands. The QMP + BP treatment was the only rearing environment without a pollen diet where protein amounts were significantly greater than the control. The synergizing effect of QMP + BP on extractable mandibular and hypopharyngeal gland protein suggests a highly derived role for the combined effect of these two primer pheromones on honey bee cooperative brood care. Mandibular gland area was significantly and positively correlated with extractable protein. Amounts of extractable protein from both glands declined significantly with age of workers in all treatments. However, treatment significantly affected rate of decline. The adaptive significance of gland protein amounts in response to pheromones and pollen diet are discussed.     

The Tail Gland of Canids

The tail gland of canids is a hepatoid glandular organ surrounded and penetrated by powerful hair erector muscles squeezing out its lipoprotein secretion onto the skin surface. The gland is most developed in solitary species (Arctic, red, and corsac foxes) where it is represented by powerful glandular layer with large secretion containers—cisterns. It is less developed in the jackal; there are cisterns but glandular lobes do not merge into a layer. In the raccoon dog, wolf, and domestic dog the gland is composed of small lobes without cisterns. Hepatoid glands of the tail gland are represented by two histological variants distinguished by the presence or absence of hydrophobic lipids in the secretory cells. The excretory ducts are formed by lipid transformation of the cellular bands.     

Alpha 2u-globulin in modified sebaceous glands with pheromonal functions: localization of the protein and its mRNA in preputial, meibomian, and perianal glands

alpha 2u-Globulin, the principal urinary protein of the male rat, has extensive sequence homology with many lipid binding proteins. The highest concentration of alpha 2u-globulin is found in the preputial gland, a holocrine secretory organ with pheromonal function. Meibomian and perianal glands are two other modified sebaceous glands with holocrine secretory cycles and pleiomorphic peroxisomes capable of synthesizing pheromonal lipids. Immunocytochemical examination shows the presence of alpha 2u-globulin in the acinar cells of all three of these modified sebaceous glands. Whereas in the preputial gland all of the acinar cells exhibit immunoreactivity, in the meibomian and perianal glands only selective cells contain alpha 2u-globulin. In the case of the preputial gland, in addition to the acinar cells some stratified epithelial cells also were immunoreactive. In the perianal and meibomian glands, keratinocytes lining nearby hair shafts and select cells of accessory oil glands stained for alpha 2u-globulin. In situ hybridization with a cloned cRNA probe confirmed the immunocytochemical data. Presence of the alpha 2u-globulin mRNA in these glands was also established by Northern blot analysis. Immunoelectron microscopic examination of preputial alpha 2u-globulin showed the presence of this protein in secretory granules of various maturational stages. Immunolabeled alpha 2u was also found in attached vesicles containing protein and lipid inclusions. The lytic cells were not only loaded with alpha 2u-globulin but also contained sharp-edged, irregularly shaped electron-dense granules which stained heavily for this protein. Specific localization of alpha 2u-globulin and its mRNA in three pheromone-producing sebaceous glands and its structural homology with known lipid binding proteins indicate a pheromone carrier role of alpha 2u-globulin.     

Deciphering the molecular mechanism of stop codon readthrough

Recognition of the stop codon by the translation machinery is essential to terminating translation at the right position and to synthesizing a protein of the correct size. Under certain conditions, the stop codon can be recognized as a coding codon promoting translation, which then terminates at a later stop codon. This event, called stop codon readthrough, occurs either by error, due to a dedicated regulatory environment leading to generation of different protein isoforms, or through the action of a readthrough compound. This review focuses on the mechanisms of stop codon readthrough, the nucleotide and protein environments that facilitate or inhibit it, and the therapeutic interest of stop codon readthrough in the treatment of genetic diseases caused by nonsense mutations.     

Localization patterns of dopamine active transporter synthesizing cells during development of brine shrimp

There have been many studies on dopamine active transporter (DAT) in humans and laboratory animals; however, there is a lack of information on DAT in brine shrimp. In this study, we demonstrated the neuronal and nonneuronal characteristics of DAT‐synthesizing (DAT⁺ cells) during development of brine shrimp. In neuronal cells, the DAT⁺ neurons in the central body and lobes of a protocerebrum (PC) controlled the deutocerebrum. The sensory cells of nauplius eyes projected their decussated axons to the PC, and the DAT⁺ cells at the posterior region were associated with migration and control of the 10 posterior neurons during the early nauplius stage. In nonneuronal cells, the five types of glands, that is, the salt, antennal, mandible, and accessory glands and posterior gland1 and gland2 synthesized DAT protein. In addition, the gut and rectum dilator muscles and renal cells expressed DAT protein. Thus, DAT protein acts in the development of several types of cells during development of brine shrimp.     

Adenosine-3',5'-monophosphate in salivary glands of unfed and feeding female lone star ticks,Amblyomma americanum (L.)

1. Basal levels of cAMP in salivary glands of female lone star ticks were found to be about 5 pmoles/mg protein during all stages of feeding.2. Glands stimulated with 10⁻⁵M dopamine and 10⁻⁵M dopamine plus theophylline exhibited significant increases in cAMP/mg protein.3. After stimulation by 10⁻⁵ M dopamine was removed, cAMP decreased faster in glands from slowly feeding ticks (< 200 mg) than in glands of rapidly feeding ticks ( > 200 mg).     

QUANTITATIVE DETERMINATION OF CANNABINOIDS IN INDIVIDUAL GLANDULAR TRICHOMES OF CANNABIS SATIVA L. (CANNABACEAE)

Cannabinoid levels of individual mature glandular trichomes from two clones and two strains of Cannabis sativa L., which included both drug and fiber phenotypes, were investigated by gas-liquid chromatographic analyses. Capitate-stalked glands were selectively harvested from vein and nonvein areas of pistillate bracts while capitate-sessile glands were harvested from these areas of leaves. The qualitative cannabinoid profile characteristic of the strain or clone was maintained in the individual capitate-stalked glands while the quantitative cannabinoid profiles varied with each strain or clone and between vein and nonvein areas as well. Capitate-sessile glands were found to contain conspicuously lower levels of cannabinoids than capitate-stalked glands. This study emphasizes that glands of Cannabis represent a dynamic system within the cannabinoid synthesizing activities of this plant.