On the role of tubificid oligochaetes in relation to fish disease with special reference to the myxozoa

Whirling disease is caused by the myxozoan parasite Myxobolus cerebralis, Hofer. It has been associated with a serious decline in wild rainbow trout populations in the western United States. The alternate host is the tubificid oligochaete Tubifex tubifex, and perhaps other tubificids. Tubifex is a very adaptable taxon, being found in various morphological forms. Polyploidy has been demonstrated. There is some suspicion that sibling species may be found to exist. Infection rates in tubificids are low. Related myxosporeans are associated with a variety of aquatic oligochaete worms belonging to three families, Tubificidae, Naididae and Lumbriculidae, and also with polychaetes. Myxozoans are now recognized as members of the phylum Cnidaria. Other fish parasites, such as the cestodes Archigetes and Caryophyllaeus and the nematode Eustrongylides, are transmitted by tubificids. The tubificid worm population in an ecosystem may provide an infective reservoir as the disease persists for long periods in the worm. Control of worm populations might be achieved by reducing organic inputs, lowering erosion, increasing flow and removing objects that accumulate pockets of silt. The use of pesticides is unlikely to be effective because of a lack of specific impact and consequent disruption of the whole benthic community, at least.     

The lichen flora of coastal saline lagoons in England

Abstract:The lichen flora associated with twenty saline lagoons in England is described. Though often scarce, lichens were present on shingle, miscellaneous stones, half-submerged concrete structures, retaining walls, salt marsh vegetation, wooden posts, and strand-line materials. Sites that had been modified by the activity of man often held richer assemblages than ones in a more natural condition. The lichen flora is a mixture of common-place species and maritime specialists. The large lagoon behind Chesil Beach, known as ‘The Fleet’, was the most important site surveyed. Many of the marine lichens present are typical of very sheltered coastlines. Caloplaca suaedae, found at two sites, is described as new to science.     

A histological and scanning electron microscope study of the formation of the wall plates in Chthamalus depressus (Poli)

Because of the small amount of pigmentation the difficulties associated with earlier histological work on Chthamalus stellatus (Poli) are absent in extreme hypobiotic C. depressus (Poli). The formation of the wall plates has been investigated by normal histological techniques and supported by scanning electron microscopy. The wall plates are covered by epicuticle which in its continuity resembles that of Acasta spongites; the epicuticle is strongly ribbed and the plate has more or less regularly spaced, volcano-like outgrowths. The various cell-types and the part they play in the expansion of the basis and growth of the wall plate are described. A series of ‘bridging’ cells are present and lie between the lower part of the last completely formed ‘scale’ and the basal cells. Growth is considered from the evolutionary point of view and in relation to the forms assumed under natural conditions, in particular to the capacity of the animal to adapt to changes in the rock surface.     

Eine neueOtarion-Art (Trilobita, Arthropoda) aus dem Greifensteiner Kalk (unteres Mittel-Devon, Unter-Eifelium) von Greifenstein bei Herborn (Hessen, Deutschland)

en|This paper deals with a new species ofOtarion [Otarion (Otarionella) greifensteinen.se n. sp.] from the ‘Greifenstein Limestone’ of the ‘Wiege’ near Greifenstein, close to the village Greifenstein near Herborn (Lahn-Dill area, Hesse, Germany), which is described, figured and compared with all known species of this subgenus. It is a typical trilobite of the hercynian-bohemian shallow marine facies near the Lower-/Middle Devonian boundary (Upper Emsian / Lower Eifelian), which extends up into the lower part of the Middle Devonian (Lower Eifelian). The trilobites are transported for short distances only and, thus, are parautochthonous elements of the Greifenstein Facies.     

The microscopic anatomy and ultrastructure of the contractile vessel in the sipunculan Themiste hexadactyla (Satô, 1930) (Sipuncula: Sipunculidea)

The microscopic anatomy and ultrastructure of the contractile vessel of the sipunculan Themiste hexadactyla (Satô, 1930) from Vostok Bay (the Sea of Japan) were studied by histological and electron microscope methods. The ultrastructural features of the internal (endothelium) and external (coelothelium) lining of the contractile vessel are described and illustrated. Numerous macromolecular filters, the so-called “double diaphragms,” were found in the external coelothelium facing the cavity of the trunk coelom. This suggests a possible filtration from the tentacular coelom into the trunk coelom though the contractile vessel wall. The microscopic peculiarities of the main tube of the contractile vessel and its numerous lateral branches twining around several internal organs are described in detail. The contractile vessel is polyfunctional: it can act as the main reservoir for the cavity fluid during the withdrawal of the tentacular crown and performs the functions of the distribution system in sipunculans.     

Corosolic acid and its structural analogs: A systematic review of their biological activities and underlying mechanism of action

BackgroundThe corosolic acid (CA), also known as plant insulin, is a pentacyclic triterpenoid extracted from plants such as Lagerstroemia speciosa. It has been shown to have anti-diabetic, anti-inflammatory and anti-tumor effects. Its structural analogs ursolic acid (UA), oleanolic acid (OA), maslinic acid (MA), asiatic acid (AA) and betulinic acid (BA) display similar individual pharmacological activities to those of CA. However, there is no systematic review documenting pharmacological activities of CA and its structural analogues. This study aims to fill this gap in literature.PurposeThis systematic review aims to summarize the medical applications of CA and its analogues.MethodsA systematic review summarizes and compares the extraction techniques, pharmacokinetic parameters, and pharmacological effects of CA and its structural analogs. Hypoglycemic effect is one of the key inclusion criteria for searching Web of Science, PubMed, Embase and Cochrane databases up to October 2020 without language restrictions. ‘corosolic acid’, ‘ursolic acid’, ‘oleanolic acid’, ‘maslinic acid’, ‘asiatic acid’, ‘betulinic acid’, ‘extraction’, ‘pharmacokinetic’, ‘pharmacological’ were used to extract relevant literature. The PRISMA guidelines were followed.ResultsAt the end of the searching process, 140 articles were selected for the systematic review. Information of CA and five of its structural analogs including UA, OA, MA, AA and BA were included in this review. CA and its structural analogs are pentacyclic triterpenes extracted from plants and they have low solubilities in water due to their rigid scaffold and hydrophobic properties. The introduction of water-soluble groups such as sugar or amino groups could increase the solubility of CA and its structural analogs. Their biological activities and underlying mechanism of action are reviewed and compared.ConclusionCA and its structural analogs UA, OA, MA, AA and BA are demonstrated to show activities in lowering blood sugar, anti-inflammation and anti-tumor. Their oral absorption and bioavailability can be improved through structural modification and formulation design. CA and its structural analogs are promising natural product-based lead compounds for further development and mechanistic studies.     

Chlorophyll fluorescence imaging can reflect development of vascular connection in grafting union in some Solanaceae species

Graft union development in plants has been studied mainly by destructive methods such as histological studies. The aim of this work was to evaluate whether the chlorophyll fluorescence imaging (CFI) technique is sensitive enough to reflect changes at the cellular level in different Solanaceae grafted plants 30 d after grafting, when both grafted partners were well fused and strong enough in all plant combinations. The pepper cultivar ‘Adige’ was grafted onto different Capsicum spp. accessions typified with different compatibility degrees; eggplant was grafted on Solanum torvum and pepper homografts as compatible unions; pepper was grafted on S. torvum and on tomato as incompatible unions. ‘Adige’/’Adige’ and ‘Adige’/pepper A25 showed a higher maximum quantum efficiency of PSII associated with higher values of actual quantum efficiency of PSII and photochemical quenching as well as with vascular regeneration across the graft interface. Our results highlighted that CFI changes reflected histological observations in grafted Solanaceae plants.     

An unusual hermaphrodite reproductive trait in the Antarctic brooding bivalve Lissarca miliaris (Philobryidae) from the Scotia Sea, Southern Ocean

The Antarctic marine environment is extreme in its low temperatures and short periods of primary productivity. Invertebrates must therefore adapt to maximise reproductive output where low temperature and limited food slow larval development. Brooding is a common reproductive trait in Antarctic marine bivalves; larval development occurs within the mantle cavity, and larvae are released as fully developed young. Lissarca miliaris is a small, short-lived, shallow-water brooding bivalve of circum-Antarctic distribution and found most abundant in the sub-Antarctic Magellan Region and islands of the Scotia Arc. Here, an unusual hermaphrodite reproductive trait is described for L. miliaris from King George Island (62°14′S, 58°38′W) and Signy Island (60°42′S, 45°36′W), Antarctica, using histological and dissection techniques. Specimens demonstrate simultaneous and sequential hermaphrodite traits; male and female gonads develop simultaneously, but the production of oocytes is reduced while testes are ripe. Functional females are more abundant in specimens above 3 mm shell length, although male reproductive tissue persists and functional males are found in all size classes. The number of previtellogenic oocytes produced by far exceeds the number of oocytes extruded and brooded, which may indicate an ancestral link to a planktotrophic past. Hermaphroditism in L. miliaris maximises reproductive efficiency in a short-lived species, in which the female’s capacity to brood its young is limited, and demonstrates a specialised adaptation to a cold stenothermal and food-limited environment prevailing in the Southern Ocean.     

The dinoflagellates Pfiesteria shumwayae and Luciella masanensis cause fish kills in recirculation fish farms in Denmark

Fish kills in two geographically separate fish farms in northern Denmark in 2012, one using marine, the other brackish water ‘Recirculation Aquaculture Systems’ (RAS), were found to be caused by Pfiesteria shumwayae and Luciella masanensis, two species of dinoflagellates belonging to the family Pfiesteriaceae. There were no other harmful algae present in either of the aquaculture plants. Serious fish kills in the US have been attributed to Pfiesteria during the past 20 years, but this type of mortality has not been documented elsewhere. L. masanensis, described recently from Korea and USA, has not been previously reported to be the source of fish kills. In the marine farm, the affected fish was rainbow trout, in the brackish water farm pikeperch. Light microscopy is presently insufficient to discriminate between the approx. 20 species of the family Pfiesteriaceae described. Identification of the two algal species was therefore based on molecular sequencing of nuclear-encoded LSU rDNA, confirmed by scanning electron microscopy and, eventually, also by examination of the very thin amphiesmal plates of the flagellates by calcofluor-stained cells in a fluorescence microscope.Although the two fish farms differed in light and salinity conditions, both farms used re-circulating water in closed circuit systems. The dinoflagellates were examined in detail and shown to feed on organic material such as live, damaged nematodes, as described for the single pfiesteriacean flagellate known from freshwater, Tyrannodinium edax. Algal cells were observed to attach to their prey by an attachment filament and subsequently used a peduncle to suck up the food. Fish farms utilizing water recirculation technology are gaining popularity due to their reduced effect on the environment. The two cases from Denmark are apparently the first RAS farms in which serious fish kills have been reported. In the marine farm (Luciella) fish mortality increased dramatically despite treatment of the water with peracetic acid and chloramine-T. The plant was temporarily closed down pending investigation into the cause of mortality and subsequently to determine a method of management to control the dinoflagellate and avoid future fish kills. In the brackish water farm (Pfiesteria), water was treated with chloramine-T, which caused the dinoflagellates to disappear temporarily from the water column, apparently forming temporary cysts. The treatment was repeated after a few days to a week, when the temporary cysts appeared to germinate and the dinoflagellates reappeared in the water column.     

Risk factors for fouling biomass: evidence from small vessels in Australia

Abstract

Invasive non-indigenous species (NIS) are a threat to marine biodiversity and marine reliant industries. Recreational vessels are recognised as an important vector of NIS translocation, particularly domestically. This paper reports on a novel application of multilevel modelling and multiple imputation in order to quantify the relationship between biofouling biomass (wet weight) and the vessel-level characteristics of recreational and fishing vessels. It was found that the number of days since the vessel was last cleaned strongly related to the biofouling biomass, yet differed dependent on vessel type. Similarly, the median number of trips undertaken was related to the biofouling biomass, and varied according to the type of antifouling paint (AF) used. No relationship was found between vessel size and biofouling biomass per sample unit. To reduce the spread of NIS, vessel owners should use an AF paint suitable to their vessel’s operational profile, and follow a maintenance schedule according to the paint manufacturer’s specifications.     

Taxonomical and palaeoecological investigations of the chondrichthyan and osteichthyan fish remains from the Middle-Late Triassic deposits of the Villány Hills (Southern Hungary)

Two sites in the Villány Hills, Hungary, have yielded rich fish assemblages from Middle to Late Triassic shallow marine deposits. The collected material comes from the Ladinian Templomhegy Dolomite Member and from the Carnian Mészhegy Sandstone Formation. The ichthyofauna is composed of both chondrichthyans (Hybodontidae indet., Palaeobates angustissimus, ‘Polyacrodus’ sp., ?Lissodus sp.) and osteichthyans (Gyrolepis sp., Birgeria sp., and further indeterminate actinopterygians). Despite the large sample size, no remains of neoselachians have been found. The Ladinian Templomhegy Dolomite is dominated by durophagous hybodontiforms (Palaeobates angustissimus, ?Lissodus sp.), but the piscivorous hybodontid and the generalist ‘Polyacrodus’ sp. are missing, while in the fish fauna collected from the Carnian Mészhegy Formation indeterminate piscivorous hybodontids are the most common elements and durophagous forms are much less abundant. The dominance of piscivorous hybodontids in the Carnian Mészhegy Sandstone could be related to the global decrease of diversity of marine fish-eating reptiles (e.g., nothosaurs) or to a change of paleoenvironmental conditions. The present study improves our knowledge on the poorly known Triassic vertebrate faunas of the Tisza Mega-unit, which formed a segment of the passive Neotethys margin of the European Plate and shows an important example of a potential vertebrate faunal shift during the Middle to Late Triassic.     

Morphological differentiation of the central visual cells R7/8 in various regions of the blowfly eye

The central rhabdomeres in the retina of the blowfly Calliphora erythrocephala and the house fly Musca domestica are not structurally uniform. In Calliphora, four classes of central rhabdomeres were found; they are formed by a total of seven types of central visual cells, clearly distinguished by the following structural features: length of the rhabdomeres R7 or R8, position of the nucleus, rhabdomere twist, fine structure in the R7/R8 transition region, and cross-sectional area of the rhabdomeres. In the lateral part of the eye only the most common central-rhabdomere class, ‘sl.’ is present, whereas in the frontal and dorsal parts classes ‘sl’ and ‘ls’ are found in a particular numerical ratio. Near the frontal eye margin the rare class ‘per’ also appears, with two separate rhabdomeres, R7per and R8s; the morphological properties of R7per are midway between those of peripheral and central visual cells. The special ommatidia at the dorsal margin of the eye are characterized by the central rhabdomeres ‘marg’. The known functional properties of the visual cells in the fly eye can be readily assigned to these classes (Table 1, Fig. 12). The non-uniform distribution of the various kinds of central rhabdomeres suggests functional differentiation of the eye region.     

Mammary serum factor initiates cell growth in 3T3 cell variants which are non-responsive to EGF

The structural organization of the histone-containing spermatozoa of the goldfish C. auratus is studied. Chemical fractionation shows that the five standard histones are present. Histone H1 subfractions are also similar to those found in other organisms. This is the first organism studied in which no peculiar basic protein is found in spermatozoa, since in all the organisms described up to now, unique protein components are always present, either alone or accompanied by somatic-like histones. Ultrastructural studies show that this chromatin is organized as a bundle of fibers of about 25 nm diameter, which upon spreading give the typical ‘beads-on-a-string’ appearance. Nuclease digestion demonstrates a repeat length of 205 base pairs (bp), slightly longer than in somatic tissues, but shorter than in echinoderm spermatozoa.     

On the evolution of ‘Indian Bison type’ strains of Mycobacterium avium subspecies paratuberculosis

Mycobacterium avium subspecies paratuberculosis (MAP), the causative agent of Johne's disease (JD) in animals, has also been linked with Crohn's disease in human beings. Lack of indigenous diagnostics and vaccine hampered control of JD in India. Designing effective control strategies require thorough understanding of the etiological agent at phenotypic and molecular levels. On the basis of cultural phenotypes and IS1311 PCR-REA typing, MAP strains have been genotyped as ‘Cattle type’, ‘Sheep type’ and ‘Bison type’. Information exists on genetic differences and comparative evolution of ‘Cattle type’ and ‘Sheep type’ strains after divergence from M. avium; however, emphasis has been little on ‘Bison type’ strains. Recently, a new ‘Indian Bison type’ genotype has been reported as principal strain infecting different animal species and human beings in India. The study analyzed few genetic markers to have inferences on the molecular evolution of native MAP isolates belonging to ‘Bison type’ genotype. Results pointed towards recent evolution of ‘Bison type’ genotype.     

The occurrence of an Eastern African haplochromine cichlid in the Ituri River (Aruwimi,Congo basin): adaptive divergence in an introduced species?

Recently, specimens belonging to the genus ‘Haplochromis’ have been found in the Ituri River (Congo basin). They clearly do not belong to any of the species known from the Congo basin, but strongly resemble ‘H’. aeneocolor from the Lake Edward/George system. We examined whether this population represents a new species or is conspecific with ‘H’. aeneocolor. A morphological comparative study was executed based on 11 counts and 23 measurements on 64 specimens. The results revealed the Ituri specimens to differ from the types of ‘H’. aeneocolor in snout length, premaxillary pedicel length and eye diameter. Since these few differences are correlated, and head morphology is known to be subject to adaptive responses in haplochromine cichlids, they were considered the result of morphological adaptation to a riverine habitat rather than an indication of heterospecificity. Probably, ‘H’. aeneocolor has accidentally been introduced into the Ituri region together with tilapias used in aquaculture, and has subsequently established a stable population in a riverine environment. As fish introductions can have a severe impact on aquatic ecosystems, improving our knowledge as well as a good management of aquacultural activities is essential.     

Fucus ‘lignin’: A reassessment

A ‘lignin’ fraction isolated by the Björkman method from the marine brown alga Fucus vesiculosus has been examined by ¹³C NMR and degradative analysis, and shown to consist of polyphloroglucinols identical to those characterized earlier from Fucus. No evidence for the presence of lignin in F. vesiculosus could be found.     

Phytoplankton composition modifies predator-driven life history evolution in Daphnia

Organisms experience competing selective pressures, which can obscure the mechanisms driving evolution. Daphnia ambigua is found in lakes where a predator, the alewife (Alosa pseudoharengus) either does (anadromous) or does not (landlocked) migrate between marine and freshwater. We previously reported an association between alewife variation and life history evolution in Daphnia. However, differences in alewife migration indirectly influence phytoplankton composition for Daphnia. In ‘anadromous lakes’, Daphnia are present in the spring and experience abundant high-quality green algae. Intense predation by young-of-the-year anadromous alewife quickly eliminates these Daphnia populations by early summer. Daphnia from ‘landlocked lakes’ and lakes without alewife (‘no alewife lakes’) are present during the spring and summer and are more likely to experience high concentrations of sub-optimal cyanobacteria during the summer. To explore links between predation, resources, and prey evolution, we reared third-generation laboratory-born Daphnia from all lake types on increasing cyanobacteria concentrations. We observed several significant ‘lake type × resource’ interactions whereby the differences among lake types depended upon cyanobacteria concentrations. Daphnia from anadromous lakes developed faster, were larger at maturation, produced more offspring, and had higher intrinsic rates of increase in the absence of cyanobacteria. Such trends disappeared or reversed as cyanobacteria concentration was increased because Daphnia from anadromous lakes were more strongly influenced by the presence of cyanobacteria. Our results argue that alewife migration and phytoplankton composition both play a role in Daphnia evolution.     

Biology of the Two-Spotted Spider Mite on Strawberry Plants

The two-spotted spider mite, Tetranychus urticae Koch, is commonly found on strawberry crops (Fragaria x ananassa). Strawberry plants have defensive mechanisms, which in turn influence the behavior of herbivores. The oviposition and development of the two-spotted spider mite were evaluated on the leaf disks of the cultivars ‘Aromas,’ ‘Camarosa,’ ‘Camino Real,’ ‘Diamante,’ ‘Diamante 10,’ ‘Diamante 50,’ ‘Festival,’ and ‘Seascape.’ It was observed that on cultivars such as ‘Aromas,’ ‘Camarosa,’ and ‘Seascape,’ immature survivorship was higher, but no difference was found during the developmental period from egg to adult of T. urticae. The immature development time was also longer on ‘Camarosa.’ Females laid more eggs on ‘Seascape’ (8.4 eggs/day), and the least on ‘Camarosa’ (1.0 egg/day). Mortality was higher at the larval stage and reached more than 50% in three cultivars ‘Camarosa,’ ‘Diamante,’ and ‘Seascape.’ Thus, the cultivars ‘Camarosa,’ ‘Diamante,’ and ‘Seascape’ were the ones that mostly affected the survival, development, and reproduction of T. urticae.