Physiological amino acids in brain tissue of the lepismatids,Lepisma saccharina and Thermobia domestica (Insecta,Thysanura)

1. The free (physiological) amino acid profile in the brain tissue of Lepisma saccharina and Thermobia domestica (Thysanura, Lepismatidae) was investigated.2. Nitrogenous waste products (ammonia and urea) together constituted 28% of the total ninhydrinpositive compounds for both species.3. GABA accounted for 3% of the total ninhydrin-positive compounds in the brain of L. saccharina, and T. domestica.4. Glutamate comprised 7% of the total ninhydrin-positive compounds in the brain of L. saccharina, and 8% in T. domestica.5. The most abundant amino acids were alanine, proline, arginine and taurine.6. The possible role of amino acids as neurotransmitters and/or modulators of neurotransmitter activity is discussed as well as the comparative free amino acid composition of the brain tissues of various arthropod groups.     

Effects of Toxoplasma gondii (Gleadle strain) on the host-parasite relationship in trichinosis.

The effects of concurrent infection with Toxoplasma gondii on the host-parasite relationship in trichinosis were studied. Infected mice showed a delay in expulsion of Trichinella spiralis adults from the gut. Persisting adult female worms were fecund but the numbers of larvae recovered from the muscles were not increased. Increased resistance to the systemic phase of trichinosis was shown by reduced numbers of muscle larvae after intravenous injection of newborn larvae in animals with toxoplasmosis as compared with control mice. There were no differences in small bowel pathology of trichinous mice with and without toxoplasmosis but inflammation around muscle cysts of T. spiralis was reduced in mice with toxoplasmosis. The eosinophilia which normally develops in mice with trichinosis was suppressed by concurrent toxoplasmosis. Trichinella infection did not alter the numbers of T. gondii cysts recovered from the brain 4 weeks after infection. It is suggested that the delay in expulsion of adult worms, decrease in muscle inflammation around T. spiralis cysts, and inhibition of eosinophilia result from immune suppression, while the reduction in numbers of muscle larvae after intravenous injection of newborn larvae reflects enhanced nonspecific resistance to infection in toxoplasmosis.     

Grazing on a toxic Alexandrium catenella bloom by the lobster krill Munida gregaria (Decapoda: Galatheoidea: Munididae)

Specimens of Munida gregaria were collected within and in the vicinity of a bloom of the toxic dinoflagellate Alexandrium catenella in Queen Charlotte Sound, New Zealand. The crustacean contained paralytic shellfish toxin (PST) with an analogue profile dominated by N-sulfocarbamoyl analogues (C1,2 and GTX5) and carbamate gonyautoxins (GTX1,4), similar to that of the dinoflagellate. A feeding experiment showed that M. gregaria is capable of actively grazing on A. catenella and it may play a role in controlling population growth of the dinoflagellate. This is the first account of the accumulation of PST by M. gregaria. When it is periodically abundant, M. gregaria is an important food item for fish, birds and other marine fauna and they are a vector by which PST may be transferred to higher trophic levels.     

The resistance of cysts of Stictodora lari (Trematoda: Heterophyidae) to encapsulation by cells of the fish host

Whereas glass beads are encapsulated by cells within 3 days after implantation into the abdominal cavity of Gambusia affinis, cysts of Stictodora lari in the same site are not encapsulated until 21–23 days after infection. The achievement of encystment in vitro demonstrated that the initial cyst wall is of parasite origin and fluorescent antibody methods showed that it does not mimic fish tissue in composition. Cysts formed in vivo have material, presumably of fish origin, associated with the cyst wall, as do living and fixed in vitro cysts following implantation.It is considered that cysts are not encapsulated for some weeks after infection because they are disguised as host tissue by material of fish origin associated with the cyst wall. An alternative explanation is proposed if the fish material does not have this functional role; the presence of spikes on the initial cyst wall may form an unsatisfactory substrate for the attachment of cells.     

Molecular Evidence for Association of Chlamydiales Bacteria with Epitheliocystis in Leafy Seadragon (Phycodurus eques), Silver Perch (Bidyanus bidyanus), and Barramundi (Lates calcarifer)

Epitheliocystis in leafy seadragon (Phycodurus eques), silver perch (Bidyanus bidyanus), and barramundi (Lates calcarifer), previously associated with chlamydial bacterial infection using ultrastructural analysis, was further investigated by using molecular and immunocytochemical methods. Morphologically, all three species showed epitheliocystis cysts in the gills, and barramundi also showed lymphocystis cysts in the skin. From gill cysts of all three species and from skin cysts of barramundi 16S rRNA gene fragments were amplified by PCR and sequenced, which clustered by phylogenetic analysis together with other chlamydia-like organisms in the order Chlamydiales in a lineage separate from the family Chlamydiaceae. By using in situ RNA hybridization, 16S rRNA Chlamydiales-specific sequences were detected in gill cysts of silver perch and in gill and skin cysts of barramundi. By applying immunocytochemistry, chlamydial antigens (lipopolysaccharide and/or membrane protein) were detected in gill cysts of leafy seadragon and in gill and skin cysts of barramundi, but not in gill cysts of silver perch. In conclusion, this is the first time epitheliocystis agents of leafy seadragon, silver perch and barramundi have been undoubtedly identified as belonging to bacteria of the order Chlamydiales by molecular methods. In addition, the results suggested that lymphocystis cysts, known to be caused by iridovirus infection, could be coinfected with the epitheliocystis agent.     

Survey for parasites ofSesamia calamistis (Lep.: Noctuidae) andEldana saccharina (Lep.: Pyralidae) in southwestern Nigeria

Field surveys were conducted during 1990–92 to document the relative abundance of different species of parasites of the lepidopterous stem borersSesamia calamistis Hampson andEldana saccharina Walker in maize fields in southwestern Nigeria. Species of parasitoids detected on both stem borers included the larvalpupal parasitoidsSturmiopsis parasitica Curran (Diptera: Tachinidae) andBrachymeria feae Masi (Hymenoptera: Chalcididae), and the larval parasitoidDolichogenidea polaszeki Walker (Hymenoptera: Braconidae). The braconidCotesia sesamiae (Cameron) was found attackingS. calamistis. The hyperparasitoidExoristobia dipterae (Risbec) (Hymenoptera: Encyrtidae) was detected on a pupa ofS. parasitica. Parasitic nematodes belonging toMermis sp. and/orHexamermis sp. were found infesting larvae of both stem borers. Overall, larval/pupal parasitization levels at Ibadan were low and ranged from 4.2 to 22.8% forS. calamistis and 1.2 to 13% forE. saccharina. Of the parasites found,S. parasitica was the most common, followed by nematodes. Four hymenopteran egg parasitoids were found attackingS. calamistis: Telenomus busseolae Gahan,T. isis Polaszek (Scelionidae),Lathromeris ovicida Risbec, andTrichogrammatoidea eldanae Viggiani (Trichogrammatidae). Egg parasitization ranged from 13.4 to 41.5%. The only egg parasitoid detected onE. saccharina wasTelenomus applanatus Bin and Johnson, which inflicted only 5% parasitization.     

Pelagic swarms and beach strandings of the squat lobster Munida gregaria (Anomura: Munididae) in the Beagle Channel, Tierra del Fuego

The present article is the first formal record of pelagic swarms and beach strandings of the squat lobster Munida gregaria in the Beagle Channel, southern South America. To describe size composition and natural diet of beach strandings and swarms, samples from strandings were taken in April 2007, March 2008 and March 2010. Samples from swarms were taken in May 2007 and April 2010. Also, during November 2008 and January 2009, two acoustic surveys were carried out to describe both, horizontal distribution and school metrics of swarms. Pelagic swarms and beach strandings were composed of 100% individuals of the morph gregaria of M. gregaria. Mean size of males and females in both, beach strandings and swarms, were similar. The diet of pelagic M. gregaria was composed mainly of crustaceans, unicellular algae and small macroalgae, sediment and particulate organic matter. Swarms of pelagic Munida took the shape of extended layers of varying density and height. Their positions in the water column were also variable: swarms were found at different depths, from the subsurface layer to near the sea bottom. Occasionally, some large swarms occupied most of the water column. In the Beagle Channel, SW winds during spring tides could be a forcing factor for M. gregaria strandings. The absence of shoaling animals in the Beagle Channel between 1997 and 2002 and the recent occurrence of swarms are coincident with their appearance in other locations in Patagonia. In consequence, we hypothesize that the factor influencing the formation of swarms must be acting at a regional scale.     

More on the life cycle of Malamoeba scolyti (Amoebidae: Sarcomastigophora) parasitizing: the bark beetle Dryocoetes autographus (Scolytidae,Coleoptera)

Some new developmental features previously unreported in, the life- cycle of an amoeba Malamoeba scolyti, which cause cysts in Malpighian tubules of the bark beetle Dryocoetes autographus, are described by means of light, phase-contrast, Nomarski interference, and electron microscopy. Two developmental phases are presumed to take place in the life cycle of M. scolyti: a phase with large multinucleate amoebae (trophozoites) developing in the gut and caecum of the host, and a phase (parasitic phase) causing cysts in the Malpighian tubules. Some data on the host-parasite relationship and rate of infection are also discussed.     

Streblonema (Ectocarpales,Phaeophyceae) infection in the kelp Laminaria saccharina (Laminariales,Phaeophyceae) in the western Baltic

The brown alga Laminaria saccharina is the dominant subtidal macroalga in Kiel Bay, western Baltic. It is infected by the microscopic brown alga, Streblonema aecidioides. Infected thalli may show symptoms of Streblonema disease, i.e. alterations of blade and stipe, ranging from dark spots to heavy deformations and completely crippled thalli. Samples taken from a single locality all year round show that (i) the host population is infected at a high rate of 87±13% (SD), but that (ii) a considerable proportion of thalli containing Streblonema does not show disease symptoms, and that (iii) juvenile hosts, which mainly appear in autumn, are infected at almost the same rate. Thus the infection seems to occur early in the host's life. Juveniles in nature show fewer symptoms of the disease than adults. Two months after infection, oxygen production and growth in laboratory-raised experimentally infected juvenile hosts was not different from uninfected controls. Experimental thalli showed more severe morphological alterations than uninfected controls only four months after infection. Both field and laboratory observations indicate that a lag phase exists between infection and outbreak of the disease.     

Tolerance of the resting cysts of Colpoda inflata (Ciliophora,Colpodea) and Meseres corlissi (Ciliophora,Spirotrichea) to desiccation and freezing

The survival of ciliate resting cysts, in the presence and absence of soil, was studied under two environmental stresses: desiccation and freezing. Laboratory strains of the common species Colpoda inflata and the rare species Meseres corlissi were used in these experiments, which yielded the following results: 1) Freezing of cysts in soil with a residual moisture level exceeding ～30% was destructive for both species. 2) Survival of Meseres corlissi cysts depended largely on the presence of soil. 3) In the absence of soil, Colpoda inflata cysts had greater tolerance to desiccation and freezing than Meseres corlissi cysts. Possible consequences for the distribution of natural populations are discussed.     

The effects of the excretory-secretory products of fouling organisms on settlement of larvae of the sponge Halichondria panicea (Pallas, 1766) (Porifera: Demospongiae)

The effects of the excretory-secretory products (ESPs) of several fouling organisms on the larvae of the sponge Halichondria panicea were assessed in laboratory experiments. The ESPs of the brown alga Laminaria saccharina significantly stimulated larval settlement and metamorphosis, while the metabolites excreted by conspecific adult colonies were harmful to H. panicea larvae. The ESPs of the ascidians Styela rustica and Molgula citrina and the blue mussel Mytilus edulis impeded both the settlement and metamorphosis of the sponge larvae to varying degrees. The chemical cues of the bivalve Hiatella arctica had no significant effect on the number of settled larvae of H. panicea but retarded their metamorphosis.     

Differential susceptibility of two locust pests to the microsporidium Paranosema (Antonospora) locustae at suboptimal rearing temperature

Paranosema (Antonospora) locustae (Canning) is a microsporidium with an extensive host range including >100 reported insect hosts from the order Orthoptera. The susceptibility of two species of locusts (Orthoptera: Acrididae) – the migratory locust, Locusta migratoria subsp. migratorioides (Fairmaire & Reiche), and the desert locust, Schistocerca gregaria Forsskål – to P. locustae was compared under laboratory conditions at a decreased temperature of 27 °C to enhance susceptibility to infection. Locusta migratoria was found highly vulnerable as infection percentages exceeded 70% at 10⁴, 10⁵, and 10⁶ spores per insect, and mortality increased with increasing dosage. Conversely, P. locustae spores were not found in S. gregaria throughout the experiment. Only at 10⁷ spores per insect, as many as 20% of S. gregaria were infected. This suggests that the desert locust is resistant to P. locustae infection, as opposed to the migratory locust. The laboratory models of these parasite–host systems may be useful for elucidating mechanisms of insect immunity to microsporidia.     

Insect pathological investigations on Swedish thysanura: A nuclear polyhedrosis virus of the bristletail Dilta hibernica

A singly enveloped NPV with fragile, spindle-shaped inclusion bodies is described from the free-living bristletail, Dilta hibernica, collected on an island on the southeastern coast of Sweden. The infection, which induces nuclear hypertrophy, is restricted to the midgut epithelium, and polyhedra are shed into the gut lumen, where virions are released, enabling reinfection to occur. The virus could not be transmitted per os to Lepisma saccharina.     

An investigation of dispersal of the introduced brown alga Undaria pinnatifida (Harvey) Suringar and its competition with some species on the man-made structures of Torquay Marina (Devon, UK)

As part of a study into the ecology of the recently introduced macroalga Undaria pinnatifida in the British Isles, the competitive ability of this adventive kelp with native species was investigated in Torquay Marina (Devon, UK). Sites of introduction were surveyed for the presence of native species filling a similar ecological niche and long-term competition experiments set up over 6 years. Experiments involving clearance, removal and monitoring showed that Undaria has a low competitive ability in the infralittoral and sublittoral of a rocky breakwater. Undaria did not manage to colonise the nearby (200 m) shoreline for at least 7 years from the date of its original introduction to the floating pontoons of Torquay Marina. Undaria did out-compete native species in a marina environment: two kelp species, Laminaria digitata and Laminaria saccharina, and a sea squirt, Styela clava.     

Artificial miniaturization causes eggs laid by crowd-reared (gregarious) desert locusts to produce green (solitarious) offspring in the desert locust, Schistocerca gregaria

The mechanism underlying the phase-dependent polyphenism in hatchling body coloration was studied by testing for a possible causal relationship with egg size in the desert locust, Schistocerca gregaria. Crowd-reared (gregarious) females typically produce large, black offspring, whereas females reared in isolation (solitarious) deposit small, green offspring. We first tested for possible genetic differences in the role of egg foam by washing or separating eggs from two strains of locust. No solitarizing effect was found in either of the strains tested, supporting a previous finding, using another laboratory strain, to show that the hatchling body coloration and size are pre-determined in the ovary of the mother and no egg foam factor is involved in the control of the hatchling body coloration. Topical application of fenoxycarb, a juvenile hormone analog (JHA), and implantation of extra corpora allata (CA), taken from Locusta migratoria, caused gregarious female adults of S. gregaria to produce small eggs. Some eggs laid by CA-implanted females produced green hatchlings. All large eggs chosen among those deposited by gregarious females produced black hatchlings. When eggs were either kept on dry filter paper at nearly saturated relative humidity during embryogenesis or pricked with a needle so that some egg yolk was squeezed out, some produced small, green hatchlings. These results suggested that the amount of egg yolk or the availability of yolk material may determine the body coloration of hatchlings.     

The Ovary of Tubifex tubifex (Clitellata,Naididae, Tubificinae) Is Composed of One,Huge Germ-Line Cyst that Is Enriched with Cytoskeletal Components

Recent studies on the ovary organization and oogenesis in Tubificinae have revealed that their ovaries are small polarized structures that are composed of germ cells in subsequent stages of oogenesis that are associated with somatic cells. In syncytial cysts, as a rule, each germ cell is connected to the central cytoplasmic mass, the cytophore, via only one stable intercellular bridge (ring canal). In this paper we present detailed data about the composition of germ-line cysts in Tubifex tubifex with special emphasis on the occurrence and distribution of the cytoskeletal elements. Using fixed material and live cell imaging techniques, we found that the entire ovary of T. tubifex is composed of only one, huge multicellular germ-line cyst, which may contain up to 2,600 cells. Its architecture is broadly similar to the cysts that are found in other clitellate annelids, i.e. a common, anuclear cytoplasmic mass in the center of the cyst and germ cells that are connected to it via intercellular bridges. The cytophore in the T. tubifex cyst extends along the long axis of the ovary in the form of elongated and branched cytoplasmic strands. Rhodamine-coupled phalloidin staining revealed that the prominent strands of actin filaments occur inside the cytophore. Similar to the cytophore, F-actin strands are branched and they are especially well developed in the middle and outermost parts of the ovary. Microfilaments are also present in the ring canals that connect the germ cells with the cytophore in the narrow end of the ovary. Using TubulinTracker, we found that the microtubules form a prominent network of loosely and evenly distributed tubules inside the cytophore as well as in every germ cell. The well-developed cytoskeletal elements in T. tubifex ovary seem to ensure the integrity of such a huge germ-line cyst of complex (germ cells - ring canals - cytophore) organization. A comparison between the cysts that are described here and other well-known female germ-line cysts is also made.     

Aspergillosis in desert locust (Schistocerka gregaria Forsk)

Fatal Aspergillus flavus infection of Desert Locust at Field Station for Investigations on Locusts, Bikaner, India, has been described. The infection appeared in the form of pinkish to brownish black patches with hardening of the affected regions, paralysis and twichings of the legs. The fungus was demonstrated in the lesions and was isolated from the diseased parts as well as from the air, floor and walls of the breeding cabin. The cool and humid conditions of the cabin favoured growth of the fungus and the air blasts helped in dissemination of its spores in the air which predisposed the disease. The infection appeared exogenous with the fungus gaining access through surface and invading the deeper tissues. It has often been observed at the Field Station for Investigations on Locusts, Bikaner, India, that the mortility rate of Desert Locust (Schistocerca gregaria Forst) at times increased to a frustating level preventing the building of a good laboratory stock (5). All the diseased and dying insects showed similar features. Sporadic deaths occured throughout the year and were preceeded by similar signs and symtoms. On 12th May 1975 following a two day dust storm about 40% of the insects in a breeding cabin developed these features and ultimately died. This paper describes investigations under taken at our end to study aetiopathogenesis of this disease.     

Active carbon uptake in Laminaria digitata and L. saccharina (Phaeophyta) is driven by a proton pump in the plasma membrane

Mechanisms for inorganic carbon acquisition in Laminaria digitata (Hudson) Lamour and L. saccharina (L.) Lamour from the Swedish west coast were studied in pH-drift experiments, using several inhibitors for different types of carbon uptake across the cell membrane. Throughout the experiments total carbon decreased in concert with a pH increase while alkalinity stayed relatively stable. Addition of acetazolamide had a strong inhibitory effect on the carbon uptake rate in L. digitata and the anion exchange protein inhibitor DIDS had a small inhibitory effect above pH 9.5. These results indicate that carbon uptake in L. digitata depends on the presence of an external carbonic anhydrase while direct bicarbonate uptake may contribute at high pH. These two mechanisms have previously been shown to occur in L. saccharina. We show that two inhibitors of H⁺-ATPases, vanadate and erythrosin B, also decreased carbon uptake rates in both Laminaria species. The effect of erythrosin B was immediate and it probably acts on the outside of the cell membrane. Contrarily, vanadate needs to be transported into the cell, where it competes with the phosphate from ATP for the aspartic acid phosphorylation site on the plasma membrane P-type H⁺-ATPase. Therefore, 1–2 h of pH drift were usually required before an inhibitory effect became apparent. Additional experiments with P-enriched and P-starved L. saccharina corroborated this process. Based on these results we suggest that the investigated Laminaria species, besides external carbonic anhydrase and DIDS-sensitive anion exchange, also possess a mechanism for the active uptake of carbon, which is dependent on plasma membrane P-type H⁺-ATPase activity. This paper also reports on the buffering capacity of the inhibitors when used in natural seawater, an aspect that has been neglected in previous studies.