The hypobranchial gland from the purple snail Plicopurpura pansa (Gould, 1853) (prosobranchia: Muricidae).ABSTRACT Results are presented on the histology of the hypobranchial gland of the marine muricid Plicopurpura pansa (Gould 1853). The general structure and secretory features were investigated using light microscopy and histochemical methods for the determination of tryptophan/indol. The hypobranchial gland of P. pansa is an antero-posteriorly elongated e·lon·gate
tr. & intr.v. e·lon·gat·ed, e·lon·gat·ing, e·lon·gates
To make or grow longer.
adj. or elongated
1. Made longer; extended.
2. Having more length than width; slender. organ located on the internal surface area of the mantle, that folds on its posterior side near the rectum, right of the ctenidia and anterior to the kidney. In dead animals it is easily distinguishable by the purple color that develops after removing the shell. Parallel to the hypobranchial gland, in the same position, can be found a black-pigmented structure, presumably pre·sum·a·ble
That can be presumed or taken for granted; reasonable as a supposition: presumable causes of the disaster. the anal gland. The secretory epithelium, which forms the hypobranchial gland consists of at least six different and very long (156.7 [micro]m) cell types. It was impossible to distinguish clearly the different histological regions of the hypobranchial gland, because the different cell types were uniformly distributed throughout the gland, with the exception of the rectal area. The number of acidophilic acidophilic /ac·i·do·phil·ic/ (as?i-do-fil´ik)
1. easily stained with acid dyes.
2. growing best on acid media. granular cells differed markedly between animals, probably because of different levels of secretion. In the mantle cavity was always found a large quantity of mucus and only occasionally acidophilic granulated gran·u·late
v. gran·u·lat·ed, gran·u·lat·ing, gran·u·lates
1. To form into grains or granules.
2. To make rough and grainy.
v.intr. secretory products. Only the two cell types with acidophilic granules Granules
Small packets of reactive chemicals stored within cells.
Mentioned in: Allergic Rhinitis, Allergies in the hypobranchial gland showed histochemically strong positive reactions for tryptophan tryptophan (trĭp`təfăn), organic compound, one of the 20 amino acids commonly found in animal proteins. Only the l-stereoisomer appears in mammalian protein. , indicating in these cells high concentrations of the precursors for "Tyrian Purple."
KEY WORDS: hypobranchial gland, purple snail, Plicopurpura pansa, Muricidae
Most marine snails in the families Muricidae and Thaididae, which make up the genera Murex mu·rex
n. pl. mu·ri·ces or mu·rex·es
Any of various marine gastropods of the genus Murex common in tropical seas and having rough spiny shells, especially M. trunculus, the source of Tyrian purple. , Thais and Plicopurpura, produce in the hypobranchial gland (mucus gland) a viscous liquid secretion containing, besides mucus and biologically active compounds, minute amounts of chromogens. These develop enzymatically in light and oxygen into a purple pigment known as "Tyrian Purple," Royal Purple" or "Shellfish Purple." Fretter and Graham (1994) considered the main function of the hypobranchial gland to be a secretor secretor /se·cre·tor/ (se-kre´ter)
1. in genetics, one who secretes the ABH antigens of the ABO blood group in the saliva and other body fluids.
2. the gene determining this trait. of mucus for trapping and cementing particulate matter sucked into the mantle cavity with the respiratory water current prior to its expulsion.
The carnivorous car·niv·o·rous
1. Of or relating to carnivores.
2. Flesh-eating or predatory: a carnivorous bird.
3. , gonochoristic, marine, muricid purple snail Plicopurpura pansa (Gould, 1853) inhabits intertidal in·ter·tid·al
Of or being the region between the high tide mark and the low tide mark.
in rocky shores exposed to high impact waves of the open sea. The range of P. pansa extends from the northwest coast of Mexico (Baja California Sur Baja California Sur (sr), state (1990 pop. 317,764), 27,571 sq mi (71,428 sq km), NW Mexico, on the Baja California peninsula. La Paz is the capital. ) (Clench 1947, Keen 1971) to northern Peru (Pena 1970, Paredes et al. 1999). The snail is not too small (shell length averages 30 mm but can be as large as 90 mm), and at low tides it is relatively easily gathered. An exceptional property of P. pansa, in comparison with that of other muricids, is that it ejects its dye-producing liquid in such large quantity, that there is no need to kill the animal to obtain the "Tyrian Purple." Furthermore, the hypobranchial gland is so active that the snails can be "milked" periodically without harming the animals (Rios-Jara et al. 1994, Naegel 2005). For these reasons it is not unexpected that P. pansa is exploited for "Tyrian Purple" production, probably since pre-Colombian times. In recent years however, with increasing public awareness of natural colors, the commercial exploitation of P. pansa for dyeing kimonos with "Tyrian Purple" had reached in Mexico such levels as to threaten the survival of the species. In 1988 P. pansa had to be declared by the Mexican government a species under special protection (Anonymous, 1988; 1994). Despite these exceptional properties of P. pansa, first as a source for "Tyrian Purple" and secondly about the state of the endangered snail populations, little is known about the principal life-history features, and many basic biological questions remain. Until now studies are lacking on the histology of the hypobranchial gland of P. pansa. The objectives of this study are to gain a better understanding of the biological function of this gland (1) by examining the general morphological features of the P. pansa hypobranchial gland using compound light microscopy; (2) determining by histochemical means the inner-cellular sites of tryptophan and (3) comparing the results with previously published reports about the histology of the hypobranchial gland from other Muricidae and Thaidae.
MATERIALS AND METHODS
More than 100 specimens of an unexploited population of P. pansa were collected in 2001 from intertidal rocks on days during extreme low-water spring tides at Playa Cerrito on the Pacific coast (23[degrees]19'54"N and 110[degrees]10'38"W), about 80 km south-west of La Paz. The average size of the males was 25.87 mm (range 14.86-43.5 mm), of the females 30.14 mm (range 13-73.9 mm).
Injecting a 10% neutral, buffered, formalin formalin /for·ma·lin/ (for´mah-lin) formaldehyde solution.
An aqueous solution of formaldehyde that is 37 percent by weight. solution into the snails preserved the tissue of the animals. About 24 h later in the laboratory eight animals were selected and removed from the shell, subsequently dehydrated de·hy·drate
v. de·hy·drat·ed, de·hy·drat·ing, de·hy·drates
1. To remove water from; make anhydrous.
2. To preserve by removing water from (vegetables, for example). in an alcohol series, cleared with butylated hydroxanisole, and embedded in paraffin. Longitudinal and transversal sections (5 [micro]m) were prepared of the bypobranchial gland, and according to the methodology by Humason (1979), stained with Ferric ferric (fĕr`ĭk), iron in the +3 valence state.
See ferrous. Hematoxylin-Eosin or Mallory Trichromic trichromic /tri·chro·mic/ (tri-kro´mik) trichromatic. stain. To prove the presence of tryptophan, as the origin of the precursors for "Tyrian Purple" (Verhecken 1989), the histochemical method for the demonstration of tryptophan (Davenport 1960) was applied.
The hypobranchial gland of P. pansa is an antero-posteriorly elongated organ located at the internal surface area of the mantle, that folds on its posterior side near the rectum, right of the ctenidia and anterior to the kidney (Fig. 1). On dead animals it is easily distinguishable by the purple color that develops after the removal of the shell. Parallel to the hypobranchial gland in the same position can be found a black pigmented structure, presumably the anal gland.
[FIGURE 1 OMITTED]
The secretory epithelium, which forms the hypobranchial gland consists of at least six different and very long (156.7 [micro]m) nonciliated cell types: (a) eosinophilic eosinophilic /eo·sin·o·phil·ic/ (-fil´ik)
1. readily stainable with eosin.
2. pertaining to eosinophils.
3. pertaining to or characterized by eosinophilia. cells with an irregular cytoplasmic texture, (b) very abundant goblet mucus cells, (c) cells with strong acidophilic granules, (d) cells with light acidophilic granules, (e) a few cells at the rectal area with very fine basophilic basophilic /ba·so·phil·ic/ (-fil´ik)
1. pertaining to basophils.
2. staining readily with basic dyes.
staining readily with basic dyes. granules and (f) empty cells.
Figure 2 shows a section of the hypobranchial gland: the basal membrane with the longitudinal muscle cells, eosinophilic and goblet mucus cells and cells with acidophilic granules. At the right side of the photograph is shown the mantle cavity with secreted mucus and acidophilic granules. At the left side is shown the external cubical cu·bi·cal
2. Of or relating to volume.
cubi·cal·ly adv. epithelium, which is in contact with the shell.
[FIGURE 2 OMITTED]
It was impossible to distinguish clearly the different histological regions of the hypobranchial gland because the different cell types were uniformly distributed in the gland. The exception was the rectal area--the only region where a cell type was found with very fine basophilic granules and where the number of mucus cells and cells with acidophilic granules was reduced. Along the glandular epithelium in the basal tissue were found a few blood vessels and a thin layer of longitudinal smooth muscle fibers.
The number of acidophilic granular cells in the hypobranchial gland differed markedly between different individuals, probably, because of the different stages of secretion. In the mantle cavity there was always a large quantity of mucus (Fig. 3), and only occasionally acidophilic granular secretory products.
[FIGURE 3 OMITTED]
Adjacent to the secretory epithelium of the hypobranchial gland is located an acinous acinous /ac·i·nous/ (as´i-nus) acinar.
made up of acini. glandular-like structure, which could be the rectal or anal gland. The acini acini Plural of acinus, eg, milk-producing glands of breast are composed of small (10 [micro]m) nonciliated cubical cells with a large quantity of fine and dark staining basophilic granules. No products of secretion were observed in the lumen of the acini, nor in the duct, which connects to the mantle cavity, the rectum, or the exterior of the snail (Fig. 4).
[FIGURE 4 OMITTED]
Only the two cell types with acidophilic granules in the hypobranchial gland showed a histochemically strong positive reaction for tryptophan, indicating that in these cells there are high concentrations of the precursors or chromogens for "Tyrian Purple."
In the Old World the production and use of "Tyrian purple" was forgotten with the fall of Byzantium (Constantinople) in 1453 A:D. Therefore, it was a big surprise to the scientific community when more than 200 y later, in 1685, William Cole was informed that at the coast of Ireland "Tyrian Purple" from marine snails was still used to mark fine linen (Cole, 1685). After many trials with different snail species at Minehead in England he found the means to obtain the precursors of "Tyrian Purple" from the muricid Nucella lapillus la·pil·lus
n. pl. la·pil·li
A small, solidified fragment of lava.
[Latin, diminutive of lapis, stone. , and the procedure for dyeing materials with them to obtain the final pigment. He made the important observation, first, that as soon as the colorless fluid is exposed to air and light it becomes immediately yellow and greenish. Soon afterwards it turns into deep emerald green, blue, deep blue, and finally reaches the purple color; and, second, that for this stepwise stepwise
incremental; additional information is added at each step.
stepwise multiple regression
used when a large number of possible explanatory variables are available and there is difficulty interpreting the partial regression chemical process light and air are needed. However, 30 y before the discovery by W. Cole about the use of "Tyrian Purple" in Ireland, the English priest Thomas Gage (1655) reported from the New World, Nicoya (Costa Rica), about the commercial exploitation of the secretions of the hypobranchial gland of P. pansa to dye garments for rich Spaniards.
Lacaze-Duthiers (1859) showed that the precursors for the pigments are not formed in the kidney or in a vein, as thought during his time, but in a band-Iike glandular epithelium located at the superior part of the internal mantle cavity. However, because of missing acini and excretory ducts he considered the glandular epithelium not to be a gland. His histological studies of the hypobranchial epithelium of muricids and thaids raised the interest of many scientists to describe in more detail the histology of the hypobranchial gland.
Letellier (1890) observed in the hypobranchial epithelium of Purpura purpura
Presence of hemorrhages in the skin, often associated with bleeding from natural cavities and in tissues. Major causes include damage to small artery walls (as in vitamin deficiency or allergic reaction) and platelet deficiency (in association with such disorders as lapillus that the purple producing cells in the middle part of the purple band are much larger, than the neighboring cells. During the same year Bernard (1890) found well-developed innervations in the base of the hypobranchial epithelium of P. lapillus, and described that the activity of neuro-epithelial cells has an impact on the production of mucus.
Erspamer (1946) showed by histochemical methods that in muricids the purple precursors and the enzyme "purpurasi" are localized in the median zone of the hypobranchial body and are kept separate, so that no reaction occurs. Hunt (1973) grouped the many different secretory cell types into two main categories: (a) acid mucin mucin: see glycoprotein. cells and (b) goblet cells. He did not include the purple producing cells. Additionally, as Bernard (1890), he found nerve cells on the base of the gland. Astonishingly a·ston·ish
tr.v. as·ton·ished, as·ton·ish·ing, as·ton·ish·es
To fill with sudden wonder or amazement. See Synonyms at surprise. , these nerve cells are not in contact with the secretory or purple producing but with ciliated cil·i·at·ed
Covered with short, hair-like protrusions, like B. coli and certain other protozoa. The cilia or hairs help the organism to move. cells (Hunt 1973).
Bolognani-Fantin and Ottaviani (1981) in a histochemical study observed in the hypobranchial gland of M. brandaris different cell types: (a) granulated cells with large, and fine granules, (b) with a homogenous cytoplasm, (c) ciliated cells having no impact on the secretion and (d) empty cells. The different granulated cells, which are only found in the middle area, could reflect different stages of purple production. In another histochemical study of the hypobranchial gland of the marine muricid Morula morula /mor·u·la/ (mor´u-lah)
1. the solid mass of blastomeres formed by cleavage of a zygote.
2. an inclusion body seen in circulating leukocytes in ehrlichiosis. granulata Srilakshmi (1991) described a similar basic arrangement of cells, like described before by Bolognani-Fantin and Ottaviani (1981) and noted the presence of neuro-sensory cells, which form the hypobranchial nerve. Roller et al. (1995) studying by means of light and electron microscopy the hypobranchial gland of the estuarine es·tu·a·rine
1. Of, relating to, or found in an estuary.
2. Geology Formed or deposited in an estuary.
Adj. 1. estuarine - of or relating to or found in estuaries
estuarial snail Stramonita (=Thais) haemastoma canaliculata defined three anatomicaly and histologically different areas with eight distinct cell types, which are randomly distributed in the gland. Among these only one is ciliated, a cell type with acidophilic granules. Others are secretory cells that release large amounts of mucus into the mantle cavity.
We observed the same basic types of cells and the great similarity between the previously described hypobranchial glands of different muricids and thaids. According to Bolognani-Fantin and Ottaviani (1981) the great number of different cells with different functions is a characteristic of the hypobranchial gland of "Tyrian Purple" producing species. Bolognani-Fantin and Ottaviani (1981) mentioned that the hypobranchial gland of a freshwater (Viviparus viviparus) and of a terrestrial (Pomatias elegans) snail species show a much simpler glandular glandular /glan·du·lar/ (glan´du-ler)
1. pertaining to or of the nature of a gland.
1. structure. Bolognani-Fantin and Ottaviani (1981) observed additionally that the cells with fine acidophilic granules react positively to phenolic phe·no·lic
Of, relating to, containing, or derived from phenol.
Any of various synthetic thermosetting resins, obtained by the reaction of phenols with simple aldehydes and used as adhesives. and indolic substances, which are considered as "Tyrian Purple" precursors. This was confirmed by Srilakshmi (1991) who found strong reactions for tryptophan and tyrosine in the hypobranchial gland. Bolognani-Fantin and Ottaviani (1981) and our results show that only the cells with acidophilic granules react positively to tryptophan. Therefore the acidophilic granulated cells found by Roller et al. (1995) in the hypobranchial gland of the muricid S. haemastoma canaliculata could be the purple producing cells.
Lacaze-Duthiers (1859) observed that when the animal contracts vigorously the cells massively open by mechanical or osmotic pressure dispersing their contents into the mantle cavity. Because of the minimal quantity of muscle fibers around the hypobranchial gland of all the earlier mentioned muricids, the likelihood of muscular stimuli is uncertain. Release of the secretion also could be stimulated by neurosecretory neurosecretory
pertaining to or emanating from the secretory activities of nerve cells.
the form in which neurosecretions are passed along axons to release them into the blood. activities, because of the presence of neurosensory neu·ro·sen·so·ry
Of or relating to the sensory activity or functions of the nervous system. cells that form the hypobranchial nerve (Srilakshmi 1991). However, there is no evidence of a connection between the nerve and the secretory cells.
Bolognani-Fantin and Ottaviani (1981) mentioned the presence of picrophilic granules on both lateral sites of the hypobranchial gland that reacted with indole indole /in·dole/ (in´dol) a compound obtained from coal tar and indigo and produced by decomposition of tryptophan in the intestine, where it contributes to the peculiar odor of feces. It is excreted in the urine in the form of indican. , but they could not relate them to the production of mucus or purple. Both authors also mentioned that in the hypobranchial gland of Murex brandaris no structural or chemical differences could be observed during the different seasons of the year.
The large number of different cell types and many possible chemical activities in the hypobranchial gland are an indication that the gland has multiple biological functions. These are yet to be discovered.
The authors acknowledge thankfully the support for this study from CONACYT CONACYT Consejo Nacional de Ciencia y Tecnología (National Board of Science and Technology; Mexico, Bolivia, Paraguay) (Project 31566-N) and from CGPI CGPI Corporate Goods Price Index (Japan)
CGPI Capital Goods Price Index (New Zealand) , COFAA and EDI (Electronic Data Interchange) The electronic communication of business transactions, such as orders, confirmations and invoices, between organizations. Third parties provide EDI services that enable organizations with different equipment to connect. (Instituto Politecnico Nacional, Mexico). A part of this study formed the basis for C.A. Aguilar-Cruz of his Licenciatura in Marine Biology. We are thankful for all the comments, critics, and for the "tweeking" of our English by Chris Cooksey (London) and by Dr. Carriker (University of Delaware  The student body at the University of Delaware is largely an undergraduate population. Delaware students have a great deal of access to work and internship opportunities. ).
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intr.v. stick·led, stick·ling, stick·les
1. To argue or contend stubbornly, especially about trivial or petty points.
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LUDWIG C. A. NAEGEL * AND CARLOS AUGUSTO AGUILAR-CRUZ
Centro Interdisciplinario de Ciencias Marinas, Instituto Politecnico Nacional (CICIMAR/IPN) Apdo. Postal 592 LA PAZ, B.C.S. 23000 Mexico
* Corresponding author. E-mail: Inaegel@ipn.mx