Observations on the attachment by the monogenean, Anoplodiscus australis, to the caudal fin of Acanthopagrus australis

The unarmed haptor of Anoplodiscus australis erodes the epidermis and attaches to the basal lamina above the stratum compactum in the caudal fin of Acanthopagrus australis by an eosinophilic, weakly PAS-positive and strongly toluidine blue-positive secretion. Ultrastructural evidence shows that the adhesive secretion, in the form of rod-shaped bodies, is produced by subtegumentary cells that connect by ducts to the thin, ventral syncytial tegument of the haptor; these bodies pass into the tegument, then coalesce in the host-parasite interface. This means of attachment has developed by an enhancement and regional specialization of the subtegumentary secretory cells associated with a syncytial tegument in monogeneans and some other platyhelminths. The available evidence indicates that the adult parasite is permanently attached.     

The missing host hypothesis: do chemical cues from predators induce life cycle truncation of trematodes within their fish host?

Using controlled experiments, the ability of the trematode parasite Stegodexamene anguillae, encysted within its intermediate fish host, the common bully Gobiomorphus cotidianus, was tested to indirectly detect the presence of its definitive host by exposing infected G. cotidianus to chemical cues from the definitive host, the short-finned eel Anguilla australis. The trematode can abbreviate its normal life cycle and achieve precocious maturity in G. cotidianus, or adopt the usual strategy consisting in delaying maturity until it reaches an A. australis. The results suggest that chemical cues from the definitive A. australis host do not affect the frequency of life cycle abbreviation in S. anguillae. Other life-history traits, such as parasite body size or the egg output of early-maturing parasites, were also unaffected by chemical cues from A. australis or from an alternative predator of G. cotidianus, the perch Perca fluviatilis, that is not a suitable host for the trematode. Therefore, factors other than A. australis host presence or abundance may be the important selective forces for life cycle abbreviation in this fish parasite.     

Multiple gene sequences delimit Botryosphaeria australis sp. nov. from B. lutea

Botryosphaeria lutea (anamorph Fusicoccum luteum) most easily is distinguished from other Botryosphaeria spp. by a yellow pigment that is formed in young cultures. This fungus has been reported from a number of cultivated hosts in New Zealand and Portugal. During a survey of Botryosphaeria fungi that occur on native Acacia species in Australia, a yellow pigment was observed in some cultures. These isolates were morphologically similar to B. lutea, but the pigment differed slightly from the one formed by authentic B. lutea isolates. Preliminary data also revealed small differences in ITS rDNA sequence data. The aim of this study was to determine whether these small differences were indicative of separate species or merely variations within B. lutea. Anamorph, teleomorph and culture morphology were compared between B. lutea and Acacia isolates from Australia. Sequence data of two other genome regions, namely the β-tubulin and EF1-α gene and intron regions, were combined with ITS rDNA sequence data to determine the phylogenetic relationship between these isolates. Isolates of B. lutea and those from Australian Acacia species were not significantly different in spore morphology. The yellow pigment, however, was much more distinct in cultures of B. lutea than in cultures from Acacia. There were only a few base pair variations in each of the analyzed gene regions, but these variations were fixed in the two groups in all regions. By combining these data it was clear that B. lutea and the isolates from Acacia were distinct species, albeit very closely related. We, therefore, propose the new epithet B. australis for the fungus from Australia. Botryosphaeria australis also was isolated in this study from exotic Sequoiadendron trees in Australia. Re-analyses of GenBank data in this study showed that B. australis also occurs on other native Australian hosts, namely a Banksia sp. and a Eucalyptus sp., as well as a native Protea sp. in South Africa and on Pistachio in Italy. These records from GenBank have been identified previously as B. lutea. The common occurrence of B. australis on a variety of native hosts across Australia suggests that this fungus is native to this area.     

Early Stages in the Differentiation of Gametocytes of Haemoproteus columbae Kruse*

SYNOPSIS The sexes of mature gametocytes of Haemoproteus columbae Kruse circulating in the blood of the domestic pigeon can be identified in the electron microscope by the same criteria that distinguish them in the light microscope. The microgametocyte has a large nucleus and pigment granules restricted to the 2 extremities of its halter-shaped cells. The macrogametocyte has dense granular cytoplasm with scattered pigment granules and a small central nucleus. The sex of young gametocytes cannot yet be recognized. When blood containing mature gametocytes is cooled outside the body of the host visible signs of gametogenesis appear within 30 seconds. The earliest signs are increasing electron lucidity of the cytoplasm and separation of the outer membrane from the body of the parasite. The membrane may form vesicles or whorls or lie free in the erythrocyte's cytoplasm. The middle membrane of the parasite becomes the plasma membrane. Axonemes and microtubules appear in the cytoplasm and nucleoplasm of the microgametocyte. The macrogametocyte lags slightly behind the microgametocyte in development. With the first signs of differentiation, the host cell cytoplasm begins to disappear. The fate of the outer membrane and the erythrocyte's cytoplasm suggests the release of a lytic substance by the parasite.     

<Emphasis Type="Italic">Anoplodiscus</Emphasis> Sonsino, 1890 (Monogenea: Anoplodiscidae): a new Australian species,and the first African record from South African hosts

Species of Anoplodiscus Sonsino, 1890 were previously only known from host members of Sparidae. A new species, Anoplodiscus hutsonae n. sp. is proposed for museum specimens originally collected from species of Scolopsis Cuvier (Nemipteridae) off Heron Island and Lizard Island, Australia. Additionally, Anoplodiscus tai Ogawa, 1994 is synonymised with Anoplodiscus cirrusspiralis Roubal, Armitage & Rohde, 1983 due to a lack of support for differential characters, and Anoplodiscus richiardii is considered a species inquirenda. Anoplodiscus cirrusspiralis causes visible lesions on the skin and fins of its host, and may also contribute to poor food conversion rates in sparid aquaculture. Anoplodiscus cirrusspiralis has been recorded from cultured sparids in Australia, Japan, South Africa, and South Korea, and was implicated as a disease agent in fish from the former two countries. However, the discovery of A. cirrusspiralis on Chrysoblephus gibbiceps (Valenciennes), Ch. laticeps (Valenciennes) and Cymatoceps nasutus (Castelnau) in South Africa, ?Pagrus major (Temminck & Schlegel) in South Korea, and P. auratus (Forster) in Australia, New Zealand and Japan suggests that this species may have a wide distribution and low host-specificity within the Sparidae. In South Africa, A. cirrusspiralis was first encountered on a morbid C. nasutus and Ch. gibbiceps from two public aquaria in 2009 (Two Oceans Aquarium, Cape Town and uShaka Sea World, Durban, respectively). Additional material was collected from C. laticeps kept at an abalone farm in Hermanus that originated from Struisbaai on the South African south coast. Anoplodiscus cirrusspiralis is redescribed from the South African specimens. This is the first record of a member of Anoplodiscidae Tagliani, 1912 from Africa.     

The “hyaline body” of the root parasiteAlectra orobanchoides benth. (Scrophulariaceae)—Its anatomy,ultrastructure and histochemistry

Summary Differentiation of a specialized tissue, the so-called hyaline body, has been demonstrated in the haustorial neck of the root parasite,Alectra orobanchoides, growing on some of its hosts,Helianthus annum L. andSesamum indicum L. This body is characterized by small, but densely structured cells and unusual extracellular deposits. The entire tissue, as well as the deposits, enlarge drastically during development of the parasite. The hyaline tissue is closely associated with conductive elements-especially the phloem-which traverse and surround the body. Histochemical characterization of the extracellular deposits revealed a polysaccharidic as well as proteinaceous components. The possible role of the hyaline body is at present still obscure.     

Endoparasite fauna of five Gadiformes fish species from the coast of Chile: host ecology versus phylogeny

The aims of the present study were to compare, using multivariate analyses, the degree of similarity of the endoparasite fauna of five fish species belonging to the order Gadiformes: Merluccius gayi, Merluccius australis, Macruronus magellanicus (Gadoidei) and Micromesistius australis and Nezumia pulchella (Macrouroidei), from the southern and central Chilean coast, and to evaluate whether the composition of the endoparasite fauna was determined by phylogenetic or ecological relationships. We employed our database of Merluccius australis, M. magellanicus and Micromesistius australis, which was complemented with published information for M. magellanicus, Merluccius australis, Micromesistius australis, M. gayi and N. pulchella. A higher number of endoparasite species was recorded for Merluccius australis, Micromesistius australis and M. magellanicus, namely Anisakis sp. and Hepatoxylon trichiuri, which is the most prevalent parasite among these hosts. Aporocotyle wilhelmi and Hysterothylacium sp. were detected only in M. gayi, whereas Lepidapedon sp. was found exclusively in N. pulchella. These results suggest that fish ecology rather than host phylogeny was the most important factor for the determination of similarity in parasite composition. This result could be explained by the similar trophic patterns of hosts and by the predominance of generalist larval species among these fish parasite communities.     

Intra-host competition between co-infecting digeneans within a bivalve second intermediate host: Dominance by priority-effect or taking advantage of others?

We experimentally investigated the interactions between two parasites known to manipulate their host's phenotype, the trematodes Acanthoparyphium sp. and Curtuteria australis, which infect the cockle Austrovenus stutchburyi. The larval stages of both species encyst within the tissue of the bivalve's muscular foot, with a preference for the tip of the foot. As more individuals accumulate at that site, they impair the burrowing behaviour of cockles and increase the probability of the parasites' transmission to a bird definitive host. However, individuals at the foot tip are also vulnerable to non-host predators in the form of foot-cropping fish which selectively bite off the foot tip of exposed cockles. Parasites encysted at the foot base are safe from such predators although they do not contribute to altering host behaviour, but nevertheless benefit from host manipulation as all parasites within the cockle are transmitted if it is ingested by a bird. Experimental infection revealed that Acanthoparyphium sp. and C. australis have different encystment patterns within the host, with proportionally fewer Acanthoparyphium metacercariae encysting at the foot tip than C. australis. This indicates that Acanthoparyphium may benefit indirectly from C. australis and incur a lower risk of non-host predation. However, in co-infections, not only did C. australis have higher infectivity than Acanthoparyphium, it also severely affected the latter's infection success. The asymmetrical strategies and interactions between the two species suggest that the advantages obtained from exploiting the host manipulation efforts of another parasite might be offset by traits such as reduced competitiveness in co-infections.     

互花米草与芦苇光合色素含量对淹水措施的响应

以上海崇明东滩入侵植物互花米草与本地种芦苇为研究对象,研究持续淹水胁迫对两种植物光合色素含量的影响.结果表明：互花米草与芦苇叶片的光合色素基本组成与含量不同,对持续淹水的响应也不同.在持续淹水胁迫下,互花米草叶绿素a、叶绿素b及类胡萝卜素含量降低,叶绿素a／b、类胡萝卜素／叶绿素值提高;芦苇各色素含量升高,叶绿素a／b、类胡萝卜素/叶绿素值基本保持稳定.解除持续淹水胁迫后,互花米草各色素含量逐渐升高,叶绿素a／b、类胡萝卜素／叶绿素值降低,并逐渐接近对照水平;而芦苇各色素含量显著高于对照.两种植物均表现出一定的补偿效应,但芦苇比互花米草更能适应同等程度的持续淹水胁迫.应用持续淹水措施治理互花米草时,可采用本地种芦苇作为治理后湿地恢复的替代植物.     

A phylogenetic analysis of pygmy perches (Teleostei: Percichthyidae) with an assessment of the major historical influences on aquatic biogeography in southern Australia

The biogeography of southern Australia is characterized by a repeated pattern of relatedness between the biota of southwestern and southeastern Australia. Both areas possess a temperate climate but are separated by a vast arid region, currently lacking permanent freshwater habitats, which has become increasingly drier since about 15 Ma. Aquatic organisms have thus potentially remained isolated for a considerable time. Pygmy perches (Nannatherina and Nannoperca, Percichthyidae) provide an excellent scenario for investigating biogeographic relationships between southwestern and southeastern regions as multiple species occur on either side of Australia. This allows us to potentially differentiate between "Multiple Invasion" and "Endemic Speciation," the two major hypotheses proposed to account for current distributions. The first suggests that multiple east-west movements have occurred, whereas the second suggests a single east-west split, with current biodiversity in each region being reciprocally monophyletic. Systematic relationships within this group were investigated with the mitochondrial cytochrome b gene; nuclear intron and exon sequences from S7, RAG1, and RAG2; and 53 allozyme loci. Our data supported the hypothesis of multiple movements across southern Australia based on a consistent lack of support for reciprocal monophyly of eastern and western species. This study appears to be the first example of an animal group displaying clear multiple east-west movement in southern Australia, as all other aquatic and terrestrial fauna previously examined displayed a single east-west split. Despite a high degree of sympatry within each region, the only evidence for hybridization was found between Nannoperca australis and N. obscura, with the latter having its mitochondrial genome completely replaced by that of N. australis, with no evidence for nuclear introgression. This is one of only a few confirmed examples of complete replacement of the mitochondrial genome in one species with that of another. Cryptic differentiation was also evident within the two most widespread species, N. australis and N. vittata, indicating that these likely consist of multiple species. We also highlight the need for multiple molecular markers with different strengths in order to obtain a more robust phylogeny, despite problems resulting from potential incongruences between data sets.     

Highly-resolving two-dimensional electrophoresis for the study of insect proteins

In this paper, we describe methods for isolation, purification and solubilization of insect proteins from various tissues, including lipid-rich fat body. An Australian locust, Oedaleus australis, and its associated dipteran parasite, Trichopsidea oestracea, provided the protein samples. Protein samples of locust fat body, haemolymph and body wall as well as parasite whole-body extracts were isolated and purified of lipids and salts using chloroform-methanol extraction. Proteins were solubilized using two types of enhanced solubilizing solutions and arrayed using two-dimensional electrophoresis. We demonstrated substantial differences between the body wall protein spectra of normal locusts and those parasitized by T. oestracea. Proteins more abundant in parasitized locusts include two 70 kDa proteins with an isoelectric point (pI) of about 5.5, one approximately 55 kDa protein cluster with a pI of about 4.7 and three 40 kDa proteins with pI values of around 5.6. Proteins that decreased in parasitized locusts include a group of 45 kDa proteins with pI values between 6 and 6.8, and a cluster of 22 to 23 kDa proteins with pI values of approximately 5.4 and 5.6.     

Changes in monogenean and copepod infestation on captive Acanthopagrus australis (Sparidae)

Infection levels by 17 species of ectoparasite on 491 yellowfin bream collected throughout 1990 from Moreton Bay, S.E. Queensland were compared to infections on 82 bream collected during the same period from a captive population in a large pond at Sea World, Gold Coast, Queensland. There was a significant increase in prevalence and/or intensity of monogeneans Lamellodiscus acanthopagri and Polylabroides multispinosus , but a decrease in the monogenean Anoplodiscus australis and the copepods Ergasilus australiensis, Lernanthropus atrox, Bomolochus stocki and Alella macrotrachelus on captive fish. Twenty-eight bream collected from the pond during autumn were placed in an experimental 1 m³ cage within the pond for 4–6 weeks. Compared to the baseline data for the pond, the caged fish showed increased prevalences of the monogeneans Lamellodiscus acanthopagri, L. squamosus, L. major and Haliotrema spariensis , and increased intensities of L. squamosus, Allomurraytrema robustum and P. multispinosus. The copepod Caligus epidemicus dropped off in preservative, but its abundance (average number per fish) was significantly higher on caged fish than on pond or wild fish. Increased infection levels by L. acanthopagri and A. robustum were due in part to autoinfection. The large skin area promoted large populations of C. epidemicus.     

A new species of Anoplodiscus (Monogenea: Anoplodiscidae) parasitic on Pagrus pagrus (Osteichthyes: Sparidae) from the coastal zone of the State of Rio de Janeiro,Brazil

A new species of Anoplodiscus (Monogenea, Anoplodiscidae), parasitic on gills of the red porgy, Pagrus pagrus, from the coastal zone of the State of Rio de Janeiro, Brazil, is described and illustrated. The new species can be differentiated from the other species of this genus by the shape of the accessory piece of the copulatory complex, and the length of the vagina. This is the first record of a species of Anoplodiscus in the Neotropical region.     

Studies on gut pigment in skin-parasitic monogeneans, with special reference to the monocotylid Dendromonocotyle kuhlii

Adults and immature specimens of the monocotylid, monogenean parasite Dendromonocotyle kuhlii contain brown gut pigment and are found on the upper skin of the stingray Amphotistius kuhlii. No indication was found that the living parasites had been feeding on blood. Tests showed that the gut pigment of the parasites is not haematin. The upper epidermis of the stingray contains pigment cells, possibly of two kinds. Although the evidence is not conclusive, it seems likely that the gut pigment of the parasite is derived from host skin pigment ingested when the parasite browses on the fish's skin. Observations on Entobdella australis, from the same host and from Taeniura lymma, support this view. The microbothriid skin parasite Pseudoleptobothrium aptychotremae also contains gut pigment which is not haematin and may be derived from pigment in the skin of its host, Aptychotrema banks.

Experimental evidence is given in support of earlier observations that Entobdella soleae does not damage host dermis during feeding.     

DNA relatedness among aquatic yeasts of the genus Metschnikowia and proposal of the species Metschnikowia australis comb. nov

DNA hybridization studies were conducted to determine the taxonomic status of the aquatic group of Metschnikowia species and their varieties. Among the DNAs of the four varieties of Metschnikowia bicuspidata, that of Metschnikowia bicuspidata var. australis showed 37 to 51% relative binding with the DNAs of Metschnikowia bicuspidata var. bicuspidata and of the varieties chathamia and californica. On this basis, low intervarietal fertility, and unique habitat in antarctic seawater, we have proposed to raise M. bicuspidata var. australis to the rank of species, Metschnikowia australis, comb. nov. DNA complementarity of Metschnikowia bicuspidata var. californica and Metschnikowia bicuspidata var. chathamia DNA was greater than 80% with that of M. bicuspidata var. bicuspidata. Metschnikowia australis can be differentiated from other Metschnikowia species and varieties by its inability to form chlamydospores, the formation of two needle-shaped ascospores per ascus, lack of glucose fermentation, and lack of assimilation of both methyl-alpha-D-glucoside and glucono-delta-lactone. Other DNA-DNA reassociation experiments showed that Metschnikowia zobellii is a distinct species when compared with both aquatic and terrestrial species of the genus.     

Sarcocystis neurona n. sp. (Protozoa: Apicomplexa), the etiologic agent of equine protozoal myeloencephalitis

Sarcocystis neuronan n. sp. is proposed for the apicomplexan taxon associated with myeloencephalitis in horses. Only asexual stages of this parasite presently are known, and they are found within neuronal cells and leukocytes of the brain and spinal cord. The parasite is located in the host cell cytoplasm, does not have a parasitophorous vacuole, and divides by endopolygeny. Schizonts are 5-35 microns x 5-20 microns and contain 4-40 merozoites arranged in a rosette around a prominent residual body. Merozoites are approximately 4 x 1 micron, have a central nucleus, and lack rhoptries. Schizonts and merozoites react with Sarcocystis cruzi antiserum but not with Caryospora bigenetica. Toxoplasma gondii, Hammondia hammondi, or Neospora caninum antisera in an immunohistochemical test.     

Neurosecretory fibres in the median eyes of the scorpion,Androctonus australis L.

Summary The retina of the median eyes of the North African scorpion, Androctonus australis L., is supplied with numerous neurosecretory nerve fibres which establish synaptoid contacts on the retinula cells. The number of fibres or profiles of varicosities of fibre terminals associated with a retinular unit (five retinula cells with a fused rhabdom) varies between 10 and 20. Electron-opaque vesicles with a diameter of 80–100 nm are abundant within the axonal profiles. The synaptoid junctions are characterized by postsynaptic electron-dense material on the inner leaflet of the retinula cell membrane and, frequently, presynaptic submembranous dense material. Because of these ultrastructural features, the junctions observed here resemble typical interneuronal synaptic contacts. Hence this kind of neurosecretory junction appears to be unique among arthropods.It is suggested that the neurosecretory fibres within the retina represent the efferent pathways for the control of the circadian pigment movements within the retinula cells.Supported by the Deutsche Forschungsgemeinschaft (F1 77/7)     

Effects of ultraviolet radiation on primary productivity in a high altitude tropical lake

A new species of the family Ancorabolidae Sars, 1909 (Copepoda, Harpacticoida), Arthropsyllus australis sp. n. was collected 1994 during 'Magellan Campaign' of RV 'Victor Hensen' and is described in the present paper. Its inclusion in the genus Arthropsyllus Sars, 1909 is justified by the diagnostic characters of the genus: lack of any dorsal or dorsolateral well-developed processes, body slightly depressed dorsoventrally, body somites with lateral epimeres except cephalothorax and last two abdominal somites. A. australis sp. n. differs from Arthropsyllus serratus Sars, 1909 in the shape of the rostrum, in having moderately-sized sensilla-bearing dorsal and dorsolateral projections on cephalothorax and body somites, and in several differences on mandible, maxillule, maxilla and swimming legs. This revised version was published online in July 2006 with corrections to the Cover Date.     

Mechanisms Explaining Nursery Habitat Association: How Do Juvenile Snapper (Chrysophrys auratus) Benefit from Their Nursery Habitat?

Nursery habitats provide elevated survival and growth to the organisms that associate with them, and as such are a crucial early life-stage component for many fishes and invertebrates. The exact mechanisms by which these benefits are afforded to associated organisms, however, are often unclear. Here we assessed potential explanations of the nursery function of structurally complex habitats for post-settlement snapper, Chrysophrys auratus, in New Zealand. Specifically, we deployed Artificial Seagrass Units (ASUs) and used a combination of video observation, netting and diet analysis of associated post-settlement snapper as well describing potential prey within the micro-habitats surrounding ASUs. We did not observe any predation attempts and few potential predators, suggesting that for snapper the nursery value of structurally complex habitats is not as a predation refuge. The diet of post-settlement snapper mostly consisted of calanoid and cyclopoid copepods, which were most commonly sampled from within the water column. Nearly all suspected feeding events were also observed within the water column. When considering the velocity of water flow at each ASU, plankton sampling revealed a greater availability of copepods with increasing current strength, while netting and video observation demonstrated that the abundance of snapper was highest at sites with intermediate water velocity. This study highlights that the interaction between water flow and food availability may represent an important trade-off between energy expenditure and food intake for post-settlement snapper. Structurally complex habitats may mediate this relationship, allowing snapper to access sites with higher food availability while reducing swimming costs. This mechanism may have broader relevance, potentially explaining the importance of estuarine nursery habitats for other species.     

Ectoparasite load is linked to ontogeny and cell-mediated immunity in an avian host system with pronounced hatching asynchrony

Several contrasting hypotheses have been proposed to account for host age-biased parasite distribution, with some of them suggesting a key role of ectoparasites in the evolution and maintenance of weight hierarchies within broods. We examined parasite distribution among individual hosts across the whole period of host exposure to the parasite in a host system that shows distinct within-brood differences in age and age-related mortality. By contrast to previous hypotheses, we found that the abundance of a haematophagous, mobile ectoparasite Carnus haemapterus on nestling European rollers ( Coracias garrulus ) was highest approximately during the mid-nestling stage of their host, coinciding with the inflection point of the host growth phase. Parasite load increased neither with absolute resource availability (i.e. body size), nor body condition index. By contrast to previous evidence, higher parasite load under natural conditions was associated with a stronger cell-mediated immune response. However, this association was moderated by low parasite densities, as well as a better brood body condition index. Overall, although we revealed remarkable host ontogenetic effects on parasite distribution, the present study suggests that a highly mobile ectoparasite generally prefers healthier hosts. We propose that, in host systems with a marked asynchrony of hatching and background mortality within the brood, parasites favour persistence rather than nutritional attractiveness of the host.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 94 , 463–473.