The effect of heavy metals on photosynthesis and loss of cell potassium in two species of marine algae,Dunaliella tertiolecta and Phaeodactylum tricornutum

Observations on sixth-stage nauplius (pre-cyprid) of the barnacle Balanus eberneus Gould treated with L-proline-3,4-H³ suggest that the cement gland in this stage is a functional organ with considerable biosynthetic activity; the activity of the cement glands in the cyprid similarly treated is relatively low, ceasing gradually during, and completely after, metamorphosis. In the early phases of this stage, the glands become highly vacuolated (degenerate), and disappear completely in 3 days. The origin of the cement apparatus in the newly metamorphosed barnacle is discussed.     

Observations on the function of the glands of the foot of the pediveliger of Ostrea edulis during settlement

The use during settlement of secretions of the 9 different types of gland in the foot of the pediveliger of Ostrea edulis L. was examined experimentally. During settlement, there is a progressive decrease in the crawling speed of the larva and a strengthening of its bond with the substratum. Both changes are related to (a) a change from ciliary to muscular pedal locomotion; (b) the increasing acidity and viscosity of the mucoid secretions used; (c) the secretion of a byssus thread by the glands of the byssus duet; (d) changes in the form and composition of this byssus. At the termination of settlement, the entire contents of 2 types of gland are discharged. Their secretions give rise to the cement which permanently fixes the larva to the substratum. The 9 types of gland are utilised sequentially in a manner closely related to the 6 phases recognised in settlement behaviour.     

Identification of trail pheromone compounds from the labial glands of the stingless bee Geotrigona mombuca

Foragers of several species of stingless bees deposit pheromone spots in the vegetation to guide recruited nestmates to a rich food source. Recent studies have shown that Trigona and Scaptotrigona workers secrete these pheromones from their labial glands. An earlier report stated that species within the genus Geotrigona use citral from their mandibular glands for scent marking. Since convincing experimental proof for this conjecture is lacking, we studied the glandular origin of the trail pheromone of Geotrigona mombuca. In field bioassays, newly recruited bees were diverted by artificial scent trails that branched off from the natural scent trail deposited by their nestmates only when they were baited with extracts from the foragers’ labial glands. Compounds extracted from the mandibular glands, however, did not release trail following behavior. This demonstrates that the trail pheromone of G. mombuca is produced in the labial glands, as in Trigona and Scaptotrigona. Furthermore, in chemical analyses citral was identified exclusively in the foragers’ mandibular glands, which disproves its supposed role as a trail pheromone. The labial glands contained a series of terpene- and wax type esters, with farnesyl butanoate as major constituent. We, therefore, postulate that the trail pheromone of G. mombuca is composed of a blend of esters.     

The histology,histochemistry and ultrastructure of the cement apparatus of three adult sessile barnacles,Elminius modestus,Balanus balanoides and Balanus hameri

The histology, histochemistry and ultrastructure of the cement gland cells of 3 species of sessile barnacles are described. Cells of both Elminius modestus Darwin and Balanus balanoides (L.) (membranous bases) are similar histologically and ultrastructurally, and within the cells there are 2 distinct regions. One is the site of secretion accumulation, the other the site of secretion synthesis. In Balanus hameri Ascanius (calcareous base) the cells are different in that the cytoplasm is more homogeneous. In all 3 species protein is the final secretion product (cement) of the cement cells. The mode of discharge of secretion from the cells differs between the membrane based and calcareous based barnacles. In the former, there is a series of collecting canals within the cytoplasm of the cement cells (intracellular canals) which join with the larger extracellular cement ducts. Secretion passes into the intracellular canals and is moved along to the larger cement ducts, which have an inner chitin lining. In Balanus hameri (calcareous base) there are no intracellular collecting canals. Secretions are thought to pass from the cement cells into the cement duct cells direct. The cement ducts in this species are not chitin lined.     

Noncovalent bonds are key mechanisms for the cohesion of barnacle (Balanus crenatus) adhesive proteins

Cement of the barnacle species, Balanus crenatus, was isolated and separated by SDS-PAGE. Reductive and nonreductive conditions yielded the same result of six major proteins (in the range up to 100 kDa) occurring as two triplets. A third triplet of lower molecular mass was faintly visible. The presence of a reductive agent had only little impact on the solubility of B. crenatus cement. The strong effect of the denaturing conditions (the presence of SDS and the incubation at elevated temperature) on the solubility of the barnacle cement and the absence of disulfide signals in Raman spectra suggest a complex structure of the barnacle cement noncovalently bound. It can be speculated that this protein complex in its quaternary structure is formed by small subunits and is equivalent to the globular cement structures previously detected.     

Scent mediation of intraspecific,interspecific, and intergeneric agonistic behavior among sympatric species of voles (Microtinae)

Summary The hypothesis that the posterolateral scent glands of male microtine rodents (Muridae) direct the attacks of other males was tested.Montane voles (Microtus montanus) and sagebrush voles (Lagurus curtatus) were established as residents in terraria, and conspecific and heterospecific males, from which posterolateral scent glands had been unilaterally removed, were introduced. More attacks by residents were aimed at the glandular sides than at the glandless sides. Male M. montanus also attacked the unilateral hip gland of longtail voles (M. longicaudus), the growth of which had been induced by exogenous hormone inasmuch as this species does not normally possess these glands. Resident male M. longicaudus did not similarly attack the induced glands of conspecific males.The findings are related to demographic patterns, mterspecific relationships, and the evolutionary development of posterolateral scent glands among microtine rodents.     

Oily substances from gastral intersegmental glands of the antPachycondyla tridenta (Ponerinae): Lack of pheromone function in tandem running and antibiotic effects but further evidence for lubricative function

Summary Gas chromatographic analyses of volatizable material from gaster intersegmental complex glands ofP. tridentata revealed the presence of linoleic acid, palmitic acid, methyl oleate, and several long-chain hydrocarbons as major constituents, which form an oily fluid mixture. The nest relocation communication ofP. tridentata is tandem running. Tandem following is mediated by pheromones as demonstrated by dummy experiments with isolated gasters and thoraces and with glass balls. The secretions of all gaster complex glands, as well as hind gut contents and metapleural gland secretions, were unable to evoke tandem following. Morphology and position of the glands, lack of pheromonal function, oily properties, low volatility, and lack of antibiotic effects of these secretions strongly suggest a function as lubricants for the ants' gastral segments.     

The trail pheromone of the ant <Emphasis Type="Italic">Crematogaster castanea</Emphasis>

Summary. The major component of the trail pheromone of the myrmicine ant Crematogaster castanea has been identified as (R)-2-dodecanol from the tibial glands of the hind legs. The substance gave activity comparable to the contents of 8 tibial glands at a concentration of 1 pg per 32 cm trail.     

Maternal provisioning of sequestered defensive steroids by the Asian snake <Emphasis Type="Italic">Rhabdophis tigrinus</Emphasis>

Summary.   Rhabdophis tigrinus obtains defensive steroids (bufadienolides) from its diet and sequesters those compounds in specialized structures on its neck known as nuchal glands. Hatchling snakes lacking these steroids must acquire them from toads consumed as prey. Here we show that females provision bufadienolides to their offspring in amounts correlated to the quantity in their own nuchal glands; thus, chemically protected mothers produce defended offspring. Bufadienolides can be provisioned to embryos via deposition in yolk and by transfer across the egg membranes within the oviducts. Maternally provisioned bufadienolides persist in the nuchal glands of juvenile snakes from the time of hatching in late summer until the following spring, when toads of ingestible size become abundant. Therefore, maternal provisioning may provide chemical protection from predators for young R. tigrinus in the absence of dietary sources of bufadienolides.     

Interspecific variation of heavy metal concentrations in the different tissues of tropical intertidal gastropods from Malaysia

The present study aims to determine the concentrations of Cd, Cu, Fe, Ni, Pb, and Zn in the different tissues of five species of tropical intertidal gastropods from Malaysia. Each of the species have organs/tissues that highly accumulated certain metals. For Cu, the mantles of Cerithidea obtusa, Pugilina cochlidium, and Murex trapa; and the digestive caeca of Thais sp. and Chicoreus capucinus highly accumulated Cu. The shells of Chi. capucinus and M. trapa, the digestive caeca of P. cochlidium, and the digestive glands of Thais sp. and Chi. capucinus highly accumulated Cd. The tentacles and the digestive caeca of Cer. obtusa and P. cochlidium, respectively, highly accumulated Zn, the digestive glands of Thais sp., Chi. capucinus, and M. trapa also highly accumulated Zn. The shells of most of the gastropods accumulated high levels of Pb and Ni. The opercula of most of the gastropods, besides the digestive glands for Thais sp., accumulated high levels of Fe. The present study on interspecific variations of heavy metals in gastropods provided information on differences of metal distributions in the different tissues, which could be useful in proposing potential tissues as better biomonitoring tools of heavy metal bioavailabilities in the coastal waters of Peninsular Malaysia.     

A new method for obtaining barnacle cement in the liquid state for polymerization studies

A new method for collecting barnacle cement in the liquid state is described. This permits studies on the transformation of cement from liquid to solid states not heretofore possible. Preliminary analyses showed that polymerization, i.e., the in vitro change from a clear liquid to an opaque solid mass is not affected by temperatures ranging from-10° to 45°C, by diluting with distilled water up to two-fold, or by treating with selective enzymes; some chemical inhibitors induce the formation of a white precipitate, possibly indicating denaturation of the protein. It is concluded that the liquid cement contains all the necessary components for self-assembly, progressively changing from a clear liquid to an opaque rubbery insoluble mass. The polymerization process is time-dependent and requires no exogenous catalyst. A mechanism that may be involved in the adhesion process of the barnacle is suggested.     

An ecdysteroid (22-acetyl-20-hydroxyecdysone) from the defense gland secretion of an insect: <Emphasis Type="Italic">Chrysolina carnifex</Emphasis> (Coleoptera: Chrysomelidae)

Summary. 22-Acetyl-20-hydroxyecdysone was identified as a major component in the secretion of elytral and pronotal glands of Chrysolina carnifex, at an estimated concentration of 1.5 x 10^-1 M. This unexpected high concentration of an ecdysteroid in an exocrine secretion of an insect is discussed in terms of its potential defensive function, and in the light of steroid production in similar glands of closely related leaf beetles.     

Condition dependence of sexual attractiveness in the bank vole

The capture of genetic variation by sexual traits due to their condition dependence is hypothesized to underlie the genetic benefits of mate choice. Here, we investigate condition dependence of sexual attractiveness of bank vole Myodes glareolus males by manipulating their diet during the period of maturation. We find that reducing diet quality negatively affected both male mating success and development of preputial glands used in sexual signaling. Preputial glands showed stronger condition dependence than other organs measured (testes, heart, intestines). In contrast to mating success, male dominance was not significantly affected by diet manipulation and was not correlated with male mating success. Thus, our results support condition dependence of sexual attractiveness but not of intrasexual competitiveness.     

Characterisation of cysteine proteinase activities in the digestive tract of juvenile <Emphasis Type="Italic">Paragnathia formica</Emphasis> isopods,ectoparasites of estuarine fish

Juveniles of Paragnathia formica Hesse (Isopoda; Gnathiidae) are haematophagous ectoparasites, feeding on fish blood which supplies the nutrients for their development through growth and moulting, and the subsequent survival and reproduction of the free-living adults. Little is known of the mechanisms of digestion in juvenile gnathiids, and biochemical studies on the digestive tract of these interesting estuarine isopods have not been undertaken previously. Here, functionally active cathepsin-like cysteine proteinases are identified in the digestive system of juvenile praniza (fed) and zuphea (unfed) forms. The physiological pH of the digestive tract and the optimum proteolytic activities detected in praniza 3 homogenates using the cathepsin B/L, cathepsin B, and cathepsin H fluorogenic substrates, N-Carbobenzoxy-Phe-Arg-4-methoxy-2-naphthylamine (Z-phe-arg-MNA), N-Carbobenzoxy-Arg-Arg-4-methoxy-2-naphthylamine (Z-arg-arg-MNA) and Arg-4-methoxy-2-naphthylamine (H-arg-MNA), respectively, are in the acidic range (pH 5.8–6.7). Inhibition profiles against Z-phe-arg-MNA and Z-arg-arg-MNA using the cathepsin B inactivator urea, and cysteine proteinase inhibitors, support the presence of cathepsin L- and B-like enzymes. These proteolytic activities are 10–50 times higher in homogenates of praniza 3 compared with zuphea 3 forms. Histochemistry of praniza 3 sections reveals that the predominant enzyme activity towards Z-phe-arg-MNA is limited to the digestive glands during early and mid stages of digestion; later, this activity appears in the lining of the anterior hindgut. Moreover, activity towards Z-arg-arg-MNA is generally restricted to the digestive glands, and only occasionally present in the anterior hindgut. In conclusion, the digestive glands are the main site of cathepsin-like cysteine proteinase activities in P. formica juveniles; these enzymes appear to be important to the digestion of host fish blood enabling development through to the free-living adult.     

Attachment of mature oysters (Saccostrea cucullata ) to natural substrata

It has been suggested that mature oysters attach to their natural substrata by means of a combination of a modification of the prismatic outer-shell layer formed within the periostracum and a “pressing” action of the mantle (Yamaguchi 1994). However, marine surfaces are seldom smooth enough to allow adhesion without the addition of a fluid adhesive to allow electromagnetic interactions to hold the two bodies together. An electron microscope study of the attachment of the oyster Saccostrea cucullata to its natural substrata has confirmed the presence of a crystalline calcareous cement. The cement shows a range of spherulitic and irregular blocky textures that are reminiscent of diagenetic cement fabrics. Their form suggests that the cement crystallises from a calcium-carbonate-saturated liquor trapped between the underside of the shell and the substratum, with crystallites nucleating on all bounding surfaces of the void. Received: 30 May 1996 / Accepted: 9 August 1996     

Pheromones and colonization: reassessment of the milkweed bug migration model (Heteroptera: Lygaeidae: Lygaeinae)

Summary. Research on insect migration has justifiably emphasized females – the so-called “oogenesis-flight syndrome”– since it is the females that place the eggs into new habitats. The large and small milkweed bugs, Oncopeltus fasciatus and Lygaeus kalmii, respectively, have featured prominently in studies of insect migration and sequestration of host plant toxins for chemical defense. Here we report that males of these species, and males of another well-studied lygaeine (Neacoryphus bicrucis), produce pheromones in glands usually considered to serve only a defensive role in Heteroptera (the metathoracic scent glands), and that these pheromones are exploited by a tachinid parasitoid as a host-finding kairomone. The pheromones are mixtures of C₆ and C₈ saturated and unsaturated esters reminiscent of lepidopteran pheromones, and the key compound of the O. fasciatus pheromone has now been correctly identified as (E)-2,7-octadienyl acetate. It is proposed that the concept of the oogenesis-flight syndrome for these kinds of insects should accommodate the role of males in the migration process. The hypothesis is presented that male-produced pheromones play a significant role in guiding colonization of new habitats in many heteropteran species. In addition, data are presented suggesting that there is a trade-off between the amount of pheromone produced by colonizing males and the host breadth of the species. Received 21 December 1998; accepted 15 February 1999.     

Chemical defense of an earwig (Doru taeniatum)

Summary. The earwig Doru taeniatum (Dermaptera, Forficulidae) has a pair of defensive glands, opening on the 4th abdominal tergite, from which it discharges a spray when disturbed. It aims the discharges by revolving the abdomen, a maneuver that enables it simultaneously to use its pincers in defense. The secretion contains two quinones (methyl-1,4-benzoquinone and 2,3-dimethyl-1,4-benzoquinone) present in the glands as a crystalline mass, together with pentadecane and a (presumably) aqueous phase. The gland openings are minute, with the result that virtually no quinone crystals are expelled with the spray. Only the two liquid phases are discharged, together with the ca. 1% quinone they carry in solution. Such a solute-economizing discharge mechanism appears to be without parallel among insect defensive glands. Received 14 February 2000; accepted 21 February 2000     

Variable transfer of detoxified metals from snails to hermit crabs in marine food chains

In any polluted marine environment, different invertebrate species contain markedly different concentrations of heavy metals. Primary producers take metals from seawater, but animals take additional metals from diets of animals, plants and detritus. Metals in a dietary organism of a food chain have varying reactivities and they follow different biochemical pathways. Excess metals are bound by ligands to form insoluble compounds within cytological compartments. These metabolic systems prevent the disruption of normal biochemical reactions by metals. The present work on Mediterranean invertebrates, initiated in Greece in 1993, used digestive glands from three species of marine snail,Monodonta mutabilis (Philippi),Cerithium vulgatum (Bruguière), andMurex trunculus (Linnaeus) as prey tissue, and hermit crabsClibanarius erythropus (Latreille) as predators; the digestive glands and faecal pellets from all animals were analysed by atomic absorption spectroscopy and x-ray microanalysis. Most metals detoxified by the snails are unavailable to the crabs and they pass straight through the gut and appear in the faecal pellets. This applies to significant proportions of the manganese, nickel, copper, zinc and silver which are bound electrostatically to phosphate or covalently to sulphur within membrane-bound intracellular compartments. Cadmium and chromium are transferred to the crabs. In digestive glands of snails, cadmium is bound to soluble highsulphur protein in the cytosol; the cytology of chromium in these animals is not known.     

Mammalian breath: trigger of defensive chemical response in a tenebrionid beetle (Bolitotherus cornutus)

Summary The tenebrionid beetle Bolitotherus cornutus everts a pair of quinone-producing defensive glands in response to mammalian breath. Experiments with a controlled airstream indicate that the beetle recognizes breath on the basis of temperature, humidity, and airflow dynamics. Under attack by mice the beetle everts the glands immediately upon being mouthed and may secure its release as a result. Against ants the beetle is protected by its tough exoskeleton and usually refrains from everting the glands. Other arthropods also show defensive responses when breathed upon.Paper No. 77 of the series Defense Mechanisms of Arthropods     

Settlement of barnacle larvae: surface structure of the antennular attachment disc by scanning electron microscopy

The surface morphology of the antennular attachment disc of the cypris larva of Balanus balanoides has been investigated by scanning electron microscopy, and its function is considered in the context of settlent behaviour. It is concluded that the attachment organ acts as an adhesive pad for temporary attachment while the larva explores the substratum. The surface of the disc is covered with villi, which could retain an adhesive substance thought to be produced by the antennular glands. The open-ended hair of the axial sense organ on the disc is shown.