Argentophilic structures of the miracidia and cercariae of Philophthalmus distomatosa n. comb. from Israel

The morphology and patterns of distribution of the argentophilic structures of miracidia and cercariae of Philophthalmus distomatosa n. comb. are described. The epidermal plate arrangement of the vast majority (94.2%) of miracidia studied conformed to the formula 6:8:4:2 = 20. The rest (5.8%) displayed the following patterns of arrangement of epidermal plates: 6:7:4:2 = 19; 6:6:4:2 = 18; and 6:4:4:2 = 16. Twenty papillalike structures were observed on the terebratorium. They were arranged along 1 axis, in 3 groups. Most commonly, 16 papillae were present on the body, located between epidermal plates of the first and second rows. The eye spots were located dorsally, near interepidermal space S1. The numbers, arrangements, and locations of the excretory pores varied. Patterns of distribution of the tegumentary papillae of P. distomatosa n. comb. cercariae are given, including those of the cephalic regions, periacetabular region, and tail. Argentophilic structures of the mentioned larval stages and of other parameters clearly distinguishing between the presently described species and those of P. lucipetus from Israel are summarized. On the basis of comparison of the presently described larval stages and those of other Melanoides tuberculata-associated larval stages of Philophthalmus in Israel and Jordan, the possibility exists that a third species occurs in Israel.     

Survival and infectivity of Hypoderaeum conoideum and Euparyphium albuferensis cercariae under laboratory conditions.

The survival characteristics of the cercariae of Hypoderaeum conoideum and Euparyphium albuferensis (Trematoda: Echinostomatidae) at 20 degrees C and 30 degrees C are described, and the age dependency of their infectivity at 20 degrees C is studied to determine their respective transmission efficiencies. Cercarial survival was found to be age-dependent and was higher at 20 degrees C. For both cercariae, the maximum life-span was 26 h at 20 degrees C and 16 h at 30 degrees C, and their respective times to 50% mortality were similar at each temperature. Both cercariae seem to be well adapted to transmission in their natural habitat, though cercarial infectivity of H. conoideum was higher than that of E. albuferensis, this being correlated with their prevalences in nature. The age-dependency of cercarial survival may be related to steadily diminishing endogenous energy levels, though the delay in attaining maximum infectivity suggests that other factors not related to energy considerations are involved in the delimitation of the cercarial infective period. However, this latter observation may constitute an adaptative mechanism allowing cercarial dissemination.     

Argentophilic structures of miracidia and cercariae of Philophthalmus lucipetus (Philophthalmidae: Trematoda) from Israel

Argentophilic structures of Philophthalmus lucipetus miracidia and cercariae from Israel are described. Eighty-four of 87 miracidia examined displayed an epidermal plate arrangement of 6:8:4:2 = 20, similar to other Philophthalmus species. Twenty papilla-like structures are arranged on the terebratorium in 3 groups, along 1 axis. Sixteen body papillae are located at the bases of epidermal plates of row 1. Eyespots are mediodorsal, between rows 1 and 2. Excretory pores are lateral, between rows 2 and 3. Features common to Israeli and Bulgarian isolates, differentiating them from other species, include the presence of 16 body papillae as opposed to 10 in other species, and a maximum of 20 papillae on the terebratorium as opposed to 19 in the others. About 3% of the miracidia displayed different plate arrangements. Among the argentophilic structures of P. lucipetus cercariae, the Israeli and Bulgarian P. lucipetus show a common pattern of 2-4 excretory pores in the tail, but arrangement of cephalic CI3 and CI5 papillae in the 2 isolates is insufficiently unequivocal for species determination. The data presented show that miracidial characteristics, rather than those of cercariae, aid in determining the species of philophthalmids. They also support former evidence attesting to the identity of the Bulgarian and Israeli species.     

Responses of dune mosses to experimental burial by sand under natural and greenhouse conditions

Sand movement is a predominant feature of mobile coastal and lake-shoreline sand dunes. Plants growing in these environments are able to withstand and survive periods of burial by sand. Although mosses are important dune stabilizers in temperate dunes, there are few studies focused on their response to burial by sand. In this study we examined the effects of burial by sand on 11 moss species that grow naturally on Lake Huron sand dunes and occur in a gradient of habitats from the foredunes along the shore to forested areas. Artificial burial treatments (sand depth of 0, 1, 3, 5 and 7 cm) were imposed under greenhouse and field conditions. We measured final plant cover and calculated the speed of emergence and an interpretive index (tolerance index) to compare burial responses among species by calculating a burial ratio which standardized the initial size of each species. In the greenhouse, Ceratodon purpureus and Ditrichum flexicaule recorded the highest mean speeds of emergence and Dicranum scoparium, Plagiothecium laetum, Dicranum flagellare and Brachythecium sp. 1 the lowest. In the field the trends were similar although the speed of emergence was much slower. Three types of response to burial were evident in plant cover: neutral, inhibition and stimulation. Although all eleven studied species were able to emerge from the different depths of burial, we observed that species colonizing areas with high sand mobility and deposition (C. purpureus and D. flexicaule) were the most tolerant and emerged from depths of up to 35 times their height. Species growing inland, at the base of trees (Dicranum scoparium, Brachythecium sp. 2, Plagiomnium cuspidatum and Dicranum flagellare) showed the least tolerance of burial.     

Proline and glycine betaine accumulation in two succulent halophytes under natural and experimental conditions

Proline (Pro) and glycine betaine (GB) contents were determined in two Mediterranean halophytes, Plantago crassifolia and Inula crithmoides, to assess their possible role in salt tolerance of both taxa. Plant material was collected in a littoral salt marsh under different environmental conditions, and from plants subjected to salt treatments in a growth chamber. Relative growth inhibition by NaCl indicated that I. crithmoides is more salt-tolerant than P. crassifolia, in agreement with the distribution of the two species in nature. Field and laboratory data confirmed GB as the major osmolyte responsible for osmotic adjustment in I. crithmoides, but with only a minor role – if any – as “osmoprotectant” in the salt tolerance of P. crassifolia. Under natural conditions, Pro contents were very low in both taxa, but increased to levels high enough to contribute significantly to osmotic balance when plants were artificially treated with 450–600 mM NaCl – higher salt concentrations than those they would normally encounter in their natural habitats. These data suggest that halophytes possess built-in mechanisms, such as accumulation of additional osmolytes, to rapidly adapt to increasing salinity levels in their natural ecosystems; for example, those expected to be caused by climate change in salt marshes in the Mediterranean region.     

Daily emergence of Schistosoma mansoni and S. haematobium cercariae from naturally infected snails under field conditions

The daily emergence of Schistosoma mansoni and S. haematobium cercariae was investigated under field conditions. Intermediate host snails of both schistosome species were collected during the rainy season, cold dry season and warm dry season and kept separately in test tubes in habitat water. Shed cercariae were collected from each of the test tubes at two hourly intervals, transferred to Petri dishes and counted. Mice were exposed to these cercariae to establish the identity of the schistosome parasites. Peak shedding for both species was observed at 1100 h during the rainy and warm dry seasons and at 0900 h during the cold dry season. Shedding before 0900 h was found only for S. haematobium in the rainy season while shedding after 1700 h occurred only during this season at both species. Shedding observed during 1900 h observation period was in the low category for both species. No shedding was observed during the 2100 h observation period for any of the species and the investigation was discontinued after this period. Only S. haematobium ova were found in the exposed mice.     

Sibling cannibalism in dorada under experimental conditions.

Cannibalism among embryos and larvae of Brycon moorei (Characidae) occurs during daytime and night-time, and persists under permanent darkness. Embryos and larvae of dorada provisioned with formulated feed over the first week of exogenous feeding did not survive, except for those exerting cannibalism. When oered alternative fish prey [embryos of Prochilodus magdalenae (0·5–0·8 mg) and Oreochromis niloticus (9·10 mg)], 1-day-old embryos of dorada preferred preying on these, thereby reducing early cannibalism. However, this promoted depensatory growth and more intense cannibalism later in the larval stage. Dorada provisioned with Artemia nauplii in excess showed more homogeneous growth and higher survival, most cannibalistic acts being restricted to the first 24 h of exogenous feeding, just after oral teeth were fully developed (21 h after hatching). Provisioning dorada with Artemia nauplii a few hours before their oral teeth were fully developed reduced early cannibalism from 41 to 15%. High proportions of deformed fish caused higher mortality, both directly and indirectly, as they promoted early cannibalism, depensatory growth and more intense cannibalism among larvae. The initial sorting of embryos, based on their occupation of the water column improved survival significantly during the first week of exogenous feeding, up to 52% in progenies containing <10% of deformed fish. Size-grading of larvae and young juveniles over the next 2 weeks reduced cannibalism to 2·6 and 1·9% day ⁻¹, in the first and second weeks, respectively. These results indicate that cannibalism in dorada can be mitigated eciently through appropriate rearing procedures, and open promising perspectives for the intensive culture of this fast-growing tropical species.     

Intra-school positional preference and reduced tail beat frequency in trailing positions in schooling roach under experimental conditions

Using three different swimming velocities and a school size of eight roach Rutilus rutilus , individual intra-school position and tail beat frequency were examined in a flume tank. Tail beat frequency was determined in defined leading and trailing positions. Individual roach showed consistent intra-school positional preferences which implied a sustained positional pattern where certain individuals took up front positions whereas other individuals swam in the rear part of the school. The positional preferences could not be attributed to inter-individual differences of the eight roach in terms of total length, mass or condition factor. At the tested swimming velocities of 2, 3 and 4  L _T s⁻¹, roach in trailing positions swam with tail beat frequencies reduced by 7·3, 11·9 and 11·6%, respectively, compared to roach in leading positions. These results suggested that roach situated in trailing positions experienced energetic savings due to hydrodynamic interactions at a wide range of swimming velocities. This may be important during migrations or when a school of roach is holding its position against the current in a lotic habitat. The observed sustained positional pattern combined with a hydrodynamic advantage in trailing positions would indicate that these energetic savings might not be evenly shared among schoolmates of roach. A positive correlation between swimming velocity and stride length was found. The present study, however, does not support any conclusions concerning these findings.     

The longevity and hatchability of Philophthalmus megalurus and P. gralli miracidia in different environmental conditions.

The effects of salinity, pH, and temperature on the longevity and hatchability of miracidia of Philophthalmus megalurus and P. gralli were determined. Miracidia of both species are able to hatch and survive at saline concentrations much above physiological levels, although these processes are reduced in 2.0--2.4% saline and completely inhibited at 2.6%. The greatest hatching rates for both species were found near neutrality (pH 6--8) but some miracidia hatched at the extreme pH levels of 3 and 12. Philophthalmus megalurus miracidia exhibited longer half-lives under acid conditions (pH 2--6) than P. gralli miracidia; conversely, P. gralli miracidia showed longer half-lives in alkaline conditions (pH 8--11). Hatching and longevity were much greater below room temperature (5--20 C) than above (30--50 C) for miracidia of both species. Temperatures above 50 C proved lethal for eyefluke eggs. Except in acid pH, P. gralli miracidia showed longer half-lives than miracidia of P. megalurus. Comparison to studies on schistosomes revealed that the inhibitory effects of physiological saline and host body temperature on the hatching process of schistosome eggs does not occur in these 2 species of eyeflukes.     

Natural selection drives leaf divergence in experimental populations of Senecio lautus under natural conditions

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Decolorization of azo dyes by Shewanella sp. under saline conditions

Wastewaters from textile processing and dye-stuff manufacture industries contain substantial amounts of salts in addition to azo dye residues. To examine salinity effects on dye-degrading bacteria, a study was carried out with four azo dyes in the presence of varying concentrations of NaCl (0-100 g l(-1)) with a previously isolated bacterium, Shewanella putrefaciens strain AS96. Under static, low oxygen conditions, the bacterium decolorized 100 mg dye l(-1) at salt concentrations up to 60 g NaCl l(-1). There was an inverse relationship between the velocity of the decolorization reaction and salt concentration over the range between 5 and 60 g NaCl l(-1) and at dye concentrations between 100 and 500 mg l(-1). The addition of either glucose (C source) or NH(4)NO(3) (N source) to the medium strongly inhibited the decolorization process, while yeast extract (4 g l(-1)) and Ca(H(2)PO(4))(2).H(2)O (1 g l(-1)) both enhanced decolorization rates. High-performance liquid chromatography analysis demonstrated the presence of 1-amino-2-naphthol, sulfanilic acid and nitroaniline as the major metabolic products of the azo dyes, which could be further degraded by a shift to aerobic conditions. These findings show that Shewanella could be effective for the treatment of dye-containing industrial effluents containing high concentrations of salt.     

Etioplast and etio-chloroplast formation under natural conditions: the dark side of chlorophyll biosynthesis in angiosperms

Chloroplast development is usually regarded as proceeding from proplastids. However, direct or indirect conversion pathways have been described in the literature, the latter involving the etioplast or the etio-chloroplast stages. Etioplasts are characterized by the absence of chlorophylls (Chl-s) and the presence of a unique inner membrane network, the prolamellar body (PLB), whereas etio-chloroplasts contain Chl-s and small PLBs interconnected with chloroplast thylakoids. As etioplast development requires growth in darkness for several days, this stage is generally regarded as a nonnatural pathway of chloroplast development occurring only under laboratory conditions. In this article, we have reviewed the data in favor of the involvement of etioplasts and etio-chloroplasts as intermediary stage(s) in chloroplast formation under natural conditions, the molecular aspects of PLB formation and we propose a dynamic model for its regulation.     

Prion removal by nanofiltration under different experimental conditions.

Manufacturing processes used in the production of biopharmaceutical or biological products should be evaluated for their ability to remove potential contaminants, including TSE agents. In the present study, we have evaluated scrapie prion protein (PrP Sc) removal in the presence of different starting materials, using virus removal filters of different pore sizes. Following 75 nm filtration, PrP Sc was detected in the filtrate by Western blot (WB) analysis when a "super-sonicated" microsomal fraction derived from hamster adapted scrapie strain 263K (263K MF) was used as the spike material. In contrast, no PrP Sc was detected when an untreated 263K MF was used. By using spike materials prepared in a manner designed to optimize the particle size distribution within the preparation, only 15 nm filtration was shown to remove PrP Sc to below the limits of detection of the WB assays used under all the experimental conditions. However, infectious PrP Sc was recovered following 15 nm filtration under one experimental condition. The results obtained suggest that the nature of the spike preparation is an important factor in evaluating the ability of filters to remove prions, and that procedures designed to minimize the particle size distribution of the prion spike, such as the "super-sonication" or detergent treatments described herein, should be used for the preparation of the spike materials.     

Culture conditions for yellow pigment formation byMonascus sp. KB 10 grown on cassava medium

An isolate ofMonascus, from a commercial, fermented soybean curd (sufu) was grown on a cassava medium. With medium at an initial pH of 7.0 an orange-red pigmentation was produced but with an initial pH below 4, a light golden pigment was obtained. A medium containing, w/v, 3% cassava starch, 0.4% peptone and 0.1% glutamic acid, with an initial pH of 2.5 was optimal for the production of this yellow pigment, which had a single maximum absorption spectrum at 330 nm. The spectroscopic characterization of the purified yellow pigments demonstrated a monascin-ankaflavin-monascorubrin skeleton.B. Yongsmith, W. Tabloka and W. Yongmanitchai are with the Department of Microbiology, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand. R. Bavavoda is with the Department of Botanical Pharmacy, Chulalongkorn University, Bangkok, Thailand.