Semper's (zoanthid) larvae: pelagic life,parentage and other problems

Semper's larvae were obtained from <300 out of 1800 plankton tows taken in the world's oceans (1964–1993). Zoanthellae (larvae of Sphenopidae) occurred at 217 stations and zoanthinae (larvae of Zoanthidae) at 86, the two larval types showing distributions clearly delimited by a minimum sea temperature (22 °C for zoanthellae, 18 °C for zoanthinae; a statistically significant difference, P<0.001). Length of formalin-fixed zoanthellae was 2–8.6 mm and of zoanthinae 1.5–5.9 mm. Endodermal zooxanthellae were present in 9/24 zoanthinae but in no zoanthellae (of 19). Three larvae contained an endo-commensal/parasitic amphipod. Septa were externally visible in larger zoanthinae and were counted in transverse sections of other larvae, a majority of which (both kinds) had 12 septa, the normal maximum. The pattern was brachycnemic in 40/43 larvae and anomalous (but non-macrocnemic) in three. If macrocnemic genera reproduce by Semper's larvae, they should have been represented in such a large sample. The distribution of adult Epizoanthus was examined: many species are deep sea (recorded down to 5000 m) but shallow-water species are relatively plentiful in, for example, the Adriatic and North Seas. No Semper's larva has ever been recorded from either. Some Parazoanthus species also occur in shallow water, especially associated with western Atlantic reef sponges. If they produce Semper's larvae, these have never been found. It is probable that macrocnemic zoanthids settle from planulae that do not develop into recognizable zoanthellae or zoanthinae.     

Phytotoxic activity of selected water-soluble metabolites of Fusarium against Lemna minor L. (Duckweed)

Phytotoxicity and inhibitory effects of the fusarial toxins fumonisin B₁ (FB₁) [m.p. 103–105 °C], fusaric acid [m.p. 106–107 °C], butenolide (4-acetamido-4-hydroxy-2-butenoic acid lactone) [116–117 °C], 9, 10-dihydroxyfusaric acid [m.p. 150–155 ° C], and moniliformin on chlorophyll synthesis in the aquatic macrophyte Lemna minor (duckweed) were examined. FB₁ proved to be most active, reducing the growth of L. minor fronds and their ability to synthesize chlorophyll by 53% and 59%, respectively, at 0.7 g/ml. The growth rate of L. minor was reduced 59% by 6.7 g/ml fusaric acid, 62% by 66.7 g/ml butenolide, and 22% by 66.7 g/ml 9,10-dihydroxyfusaric acid. Moniliformin was the least phytotoxic to L. minor, with only a 16% suppression of growth rate and a 54% reduction in chlorophyll at 66.7 g/ml.The mention of firm names or trade products does not imply that they are endorsed or recommended by the US Department of Agriculture over other firms or similar products not mentioned.     

Effects of constant and fluctuating temperatures on sporulation and infection by the aphid-pathogenic fungus Pandora neoaphidis

Laboratory studies were performed to assess the importance of temperature on sporulation and infection by the aphid-pathogenic fungus Pandora neoaphidis (Remaudière and Hennebert) Humber. Numbers of primary conidia discharged from mycelium formulated as alginate granules and unformulated mycelial mats were assessed, as well as infection of the potato aphid, Macrosiphum euphorbiae (Thomas) (Homoptera, Hemiptera, Aphididae), using culture plugs as inoculum sources. Sporulation from experiments at constant temperatures indicated the optimum temperature range was 10–20°C for both mycelial preparations and there was no or very little sporulation at 30°C. Infection of aphids kept at 15°C was 34–50%, while infection at 25°C was 11–44%. At 20°C, 77–79% of aphids were infected. Under fluctuating temperature cycles, conidia numbers did not differ when mycelial preparations were maintained at 18–25°C compared with 18–20°C, but fewer conidia were recorded when preparations were exposed continuously to 18–30°C. Infections of inoculated aphids kept for varying numbers of days at 18–25°C varied between 24–47%, but only 3–32% of aphids were infected when exposed to a cycle of 18–30°C for various times. Unformulated mycelial mats of P. neoaphidis appear to be superior to forumlated alginate granules for use in experimental greenhouse and field trials, since temperature stability is similar for both materials but mycelial mats are much easier to produce.     

Flash Heating on the Early Earth

It has been suggested that very large impact events ( 500 km diameter impactors) sterilized the surface of the young Earth by producing enough rock vapor to boil the oceans. Here, we consider surface heating due to smaller impactors, and demonstrate that surface temperatures conducive to organic synthesis resulted. In particular, we focus on the synthesis of thermal peptides. Previously, laboratory experiments have demonstrated that dry heating a mixture of amino acids containing excess Asp, Glu, or Lys to temperatures 170 °C for 2 hours yields polypeptides. It has been argued that such temperature conditions would not have been available on the early Earth. Here we demonstrate, by analogy with the K/T impact, that the requisite temperatures are achieved on sand surfaces during the atmospheric reentry of fine ejecta particles produced by impacts of bolides 10–20 km in diameter, assuming 1 – 100 PAL CO2. Impactors of this size struck the Earth with a frequency of 1 per 104 – 105 y at 4.2 Ga. Smaller bolides produced negligible global surface heating, whereas bolides > 30 km in diameter yielded solid surface temperatures > 1000 K , high enough to pyrolyze amino acids and other organic compounds. Thus, peptide formation would have occurred globally for a relatively narrow range of bolide sizes.     

Upstream non-coding region which confers polar expression to Ri plasmid root inducing gene rolB

Summary Root differentiation could be elicited on carrot discs by transformation with the agropine Ri plasmid rolB gene cloned in the binary vector Bin19, provided two conditions were met. Firstly, an adequate auxin supply had to be provided. This was achieved by co-inoculation with a strain carrying only the auxin synthetic genes of the T_R-DNA. Most of the resulting roots were then shown to harbour only rolB and no aux genes. Secondly, an extended non-coding region (1200 bp) at the 5 end of rolB had to be included in the construction. A shorter (300 bp) 5 region, including TATA and CCAAT boxes, was not sufficient to trigger root differentiation. Both the extended (B1185) and reduced (B310) 5 regions of rolB were then cloned upstream of the -glucuronidase (GUS) reporter gene and infections carried out both on the apical and on the basal side of carrot discs. Strong expression of GUS, visualized histochemically as an intense blue colouring of transformed cells was observed with B1185-GUS constructions on the apical side of the discs. Only occasionally could coloured cells be observed on the basal side of the discs with B1185-GUS and on both apical and basal sides with B310-GUS constructions. Strong GUS expression was, on the contrary, achieved on cells of both auxin-rich (apical) and auxin-depleted (basal) sides of the discs with the strong constitutive viral promoter, CaMV35S. These results indicate the presence of an upstream regulatory region which confers polar expression to the rolB gene and suggest a role for auxin in its activation.     

Functional expression of keratinase (kerA) gene from Bacillus licheniformis in Pichia pastoris

A 1.2 kb DNA fragment coding for the pro-peptide and mature keratinase from Bacillus licheniformis PWD-1 (kerA) was cloned into vectors pPICZA and pGAPZA for extracellular expression in the methylotrophic yeast, Pichia pastoris. Recombinant keratinase was secreted by the pPICZA-kerA transformants 24 h after methanol induction of shake-flask cultures, and reached a final yield of 124 mg l^–1 (285 U ml^–1) 144 h after the induction. The recombinant keratinase was glycosylated ( 39 kDa), and was optimal between pH 8.5–9.5 and between 55°C –60°C using azokeratin as substrate. The enzyme degraded bovine serum albumin, collagen, and soy protein concentrate. In conclusion, P. pastoris can be used as an efficient host to express keratinase for nutritional and environmental applications.     

Myosatellite cells associated with different muscle fibre types in the Atlantic hagfish (Myxine glutinosa,L.)

Summary The incidence of myosatellite cells associated with white and red muscle fibres of the parietal muscle and red fibres of the craniovelar muscle was estimated by quantitative electron microscopy in the Atlantic hagfish (Myxine glutinosa, L.). Myosatellite cell nuclei constitute 3, 11 and 23 % of the total number of nuclei inside the basal lamina of the three types of muscle fibres, respectively. However, the total number of nuclei is highest in white fibres, most of the nuclei belonging to striated muscle cells. Myosatellite cell profiles in transverse sections constitute 23, 41 and 61 % of the number of muscle fibre profiles of the three types, respectively. The intervals between adjacent myosatellite cells are 135 m in white fibres, 55 m in red parietal fibres, and only 25 m in craniovelar fibres. Since craniovelar fibres are also comparatively thin, myosatellite cells constitute a significant fraction of the volume inside the basal lamina in these fibres. The myosatellite cells are 30–50 m long and up to 5 m thick. Some myosatellite cells possess few organelles, whereas others appear to contain many free ribosomes, granular endoplasmic reticulum, prominent Golgi apparatus and lysosome-like bodies.This investigation was supported by the Norwegian Research Council for Science and the Humanities (NAVF grant No. C20.30–37). The authors are indebted to Jorunn Line Vaaland and Berit Branil for technical assistance, and to Dr. Finn Walvig, Biological Station, University of Oslo, Drøbak, for supplying the hagfish     

rDNA targeted oligonucleotide primers for the identification of pathogenic yeasts in a polymerase chain reaction

Summary Species-specific oligonucleotide primers were designed for PCR identification of the basidiomycetous yeastsCryptococcus neoformans, Trichosporon cutaneum andRhodotorula mucilaginosa. The procedure uses standard PCR components including DNA from the test species and three primers: two universal external (upstream and downstream) limiting primers and a species-specific internal primer. Species identification requires the formation of a species-specific rDNA nucleotide segment that is significantly smaller (200 bp) than a non-target segment (600 bp). The procedure can be used to identify yeasts from single and mixed populations.This paper is dedicated to Professor Herman Jan Phaff in honor of his 50 years of active research which still continues.     

Efficient secretion of human lysozyme from the yeast, <Emphasis Type="Italic">Kluyveromyces lactis</Emphasis>

Efficient secretion of human lysozyme from the yeast, Kluyveromyces lactis, was achieved by using more stable vectors in the order of S11 replication origin-containing episomal vector < full-length K. lactis plasmid pKD1-containing vector < centromeric vector < chromosome-integrated vectors. Cells containing a PGK (phosphoglycerate kinase) promoter-driven integration vector grown in non-selective rich medium achieved the highest level of secretion, 100 g lysozyme secretion ml ^–1 culture: this level was 10-fold higher than that achieved by episomal vectors. An additional copy of the protein disulfide isomerase gene further facilitated the secretion.     

An evaluation of some natural enemies of Spodoptera exigua on sugarbeet in northern California

Eggs and small to medium-sizedlarvae of Spodoptera exigua (Hübner)(Lepidoptera: Noctuidae) are exploited by acomplex of natural enemies in spring-plantedsugarbeet fields in northern California. Fieldstudies revealed that predation on sentinel eggmasses ranged from 20 to 100%egg mass;predation rate was lowest in fields previouslytreated with methomyl and highest innon-treated fields. Predators typicallydestroyed all of the eggs in a given egg mass;percentage predation per egg mass was densityindependent (spatial context). Survival of eggs(to neonate larvae) in cages that excludedpredators ranged from 80 to $>$90%. Theegg-predator guild consisted of adults andnymphs of Orius tristicolor(White)(Anthocoridae), Nabis americoferusCarayon (Nabidae), Lygus hesperus Knight(Miridae), and Geocoris punctipes (Say)(Geocoridae); larvae of Chrysoperlacarnea (Stephens) (Chrysopidae); and adults ofCollops vittatus (Say) (Melyridae). Laboratory evaluation revealed that largelarvae of C. carnea and the adults of theother species (except for O. tristicolor)could consume 100 eggs of S. exigua in a48 h period. The parasite guild associatedwith small and medium-sized larvae consisted ofthree species: Hyposoter exiguae(Viereck) and Pristomerus spinator (F.)(Ichneumonidae), both larval endoparasites; andChelonus insularis Cresson (Braconidae),an egg-larval endoparasite. Parasitization in field samples ranged from 30 to 65%. Smalland medium-sized larvae were also infected witha nuclear polyhedrosis virus (NPV); rates ofNPV infection ranged from 0 to 35% in fieldsamples. These results are consistent withanecdotal evidence that natural enemies,primarily generalist predators, are largelyresponsible for maintaining populations ofS. exigua at relatively low levels innontreated sugarbeet fields.     

Serotonin-immunoreactive and dopamine-immunoreactive neurones in the terminal ganglion of the cricket,Acheta domestica: Light- and electron-microscopic immunocytochemistry

Summary The distribution and ultrastructure of serotonin- and dopamine-immunoreactive (5-HTi and DAi) neurones have been investigated in the terminal ganglion of the cricket, Acheta domestica, using a pre-embedding chopper technique. Special attention has been paid to the immunoreactive structures in the neuropil. 5-HTi structures are extensively distributed and densely packed throughout the 5 neuromeres of the terminal ganglion and originate from several interneurones and efferent neurones. In contrast, DAi fibres are distributed sparsely although they extend to all neuromeres of the ganglion and originate from 6 interneurons only. For both 5-HTi and DAi neurones characteristic axonal projections and branching patterns can be distinguished. The 5-HTi axons exhibit rich varicose arborizations, whereas DAi neurones possess fewer varicosities in the neuropil. Electron microscopy shows that 5-HTi varicosities contain small ( 60 nm) and large ( 100 nm) agranular vesicles, and large ( 100 nm) granular vesicles, whereas in DAi varicosities small ( 60 nm) agranular and large ( 100 nm) granular vesicles are seen. Both 5-HTi and DAi varicosities form synaptic contacts. We conclude that both serotonin and dopamine may be used as neurotransmitters in the terminal ganglion of the cricket.Fellow of the Alexander von Humboldt-Stiftung     

Effect of<Emphasis Type="Italic"> p</Emphasis>CO<Subscript>2</Subscript> and temperature on the boron isotopic composition of the zooxanthellate coral<Emphasis Type="Italic"> Acropora</Emphasis> sp.

Culture experiments were carried out with Acropora sp. (a branching scleractinian coral) in seawater at two pCO₂ conditions (438 and 725 µatm) and two temperatures (25 and 28 °C) in order to establish the pH and temperature dependence of the boron isotopic composition of the skeleton. A clear pCO₂ effect, but no temperature effect, on the coral boron isotope composition is seen. For corals cultured at normal pCO₂ (438 µatm), the ¹¹B of the skeleton was 24.0±0.2 at 25 °C, and 23.9±0.3 at 28 °C. The values of ¹¹B measured for corals cultured at higher pCO₂ (725 µatm) were lower: 22.5±0.1, and 22.8±0.1 at 25 and 28 °C, respectively. The ¹¹B of corals cultivated at both high and normal pCO₂ conditions are consistent with a dominant pH control, and are very close to that calculated from theoretical considerations. Thus, the corals do not seem to significantly alter ambient seawater for calcification with respect to pH. Co-variation between boron and carbon isotope values is explored.Communicated by: Guest Editor A. Grottoli     

Fine structure of the flagellar apparatus of gametesin situ and motile zygotes of the green algaUlothrix flacca var.Roscoffensis (Ulotrichales) (Chlorophyta)

Summary This fine structural study ofUlothrix flacca (Dillw.) ThuretRoscoffensis variety (Berger-Perrot), a marineUlothrix, describes in detail the flagellar apparatus configuration of gametesin situ in the gametangia and in motile zygotes. The gametes's flagellar apparatus shows two basal bodies overlapping at their proximal end at a 30° angle, in an 11/5 o'clock configuration or with a counterclockwise absolute orientation. The basal bodies are interconnected by a non-striated band or capping plate. They are wrapped in their proximal part by an electron-dense sheath and obtured by a bilobed terminal cap. A cruciate microtubular root system having a 4-2-4-2 alternation pattern is present. A striated microtubule associated component (S.M.A.C.) or system I fibres accompany the two membered root R₂. The system II fibres or rhizoplasts along with striated bands associated to the microtubular roots, were not observed and are presumed to be absent.In the motile zygotes, the basal bodies are paired in a cruciate pattern. During the fusion process, two basal bodies, one of each pair, slide in a face to face position with a slight displacement into the 11/5 o'clock direction; the other two make a 30° counterclockwise rotation, thus making a 60° angle between the two basal bodies of each pair instead of 30° in the gamete.After comparison with the flagellar apparatus of other green alga gametes, it is concluded that the taxonomic affinities ofUlothrix flacca var.Roscoffensis, lie with theUlvophyceae sensuStewart andMattox 1978.Abbreviations CP capping plate - ER endoplasmic reticulum - G Golgi body - LG lipid globule - M mitochondria - MS presumed mating structure - N nucleus - R ₂,R ₄ microtubular roots - SH sheath - SMAC striated microtubule associated component - TC terminal cap - V vacuole - Ve vesicles in the anterior papilla - 1, 2, 1, 2 basal bodies numerotation     

Development, survival and reproduction of Euseius finlandicus (Acari: Phytoseiidae) at different constant temperatures

Development, survival and reproduction of Euseius finlandicus Oudemans were studied at seven constant temperatures (15, 20, 25, 27, 30, 32 and 34°C) in the laboratory. Within the temperature range tested, developmental period from egg to adult varied from 148 to 360.5h and 133.7 to 336.5h for females and males, respectively. The lower thermal threshold for immature development for females and males was 8.9 and 6.4°C, respectively. Survival during immature development exceeded 90% at all the temperatures from 15 to 32°C, but at 34°C an abrupt decline was recorded. Female longevity decreased gradually from 82.7d at 15°C to 12.2 d at 34°C. The mean generation time ranged from 44.3d at 15°C to 15.9d at 32°C. The highest r _m value (0.2817) was obtained at 30°C and the lowest at 15°C (0.0976). Temperatures above 30°C had an adverse effect on population increase.     

Genetics of the sex ratio anomaly in Drosophila hybrids of the Virilis group

Summary A study was made of the effect of genotype and temperature (25 and 17°C) on sex ratio in the hybrids D. virilis Sturt. X D. littoralis Sokolov. A genetic system has been found controlling sex-differential viability. In the F₁ of the reciprocal hybrids D. virilis X D. littoralis the sex ratio is normal, though at 17°C females are slightly excessive. The abnormal sex ratio is observed only in the progeny of test crosses.The major gene causing the death of female progeny of the cross [ (, D. virilis x , D. littoralis) x D. virilis] x D. littoralis is located on chromosome 2 of D. virilis. It is expressed as a lethal if chromosome 5 is heterogeneous virilis-littoralis. Chromosome 3 of D. virilis bears a modifier-enhancer and chromosome 5, a suppressor, of this lethal found in chromosome 2. This genetic system has a maternal effect and functions at 25°C, interacting with the X-chromosome of D. littoralis. If the maintainance temperature is lowered to 17°C, the progeny of the cross hybrid FB₁ x D. littoralis is predominantly female. Partial death of males is accounted for by a disturbance in the interaction between the genes of X-chromosome in certain combinations with the D. virilis autosomes and the Y-chromosome of the paternal species D. littoralis.Sex-differential mortality in the hybrids D. virilis x D. littoralis is one of the isolating factors between these species which does not appear to act until the second and subsequent F₁ generations due to the formation of the recombination load.     

Characterization of extracellular glucoamylase from the ectomycorrhizal mushroom <Emphasis Type="Italic">Lyophyllum shimeji</Emphasis>

To investigate the function of amylases in the fruit-body formation of an ectomycorrhizal fungus, Lyophyllum shimeji, we purified the extracellular amylase in the medium of this fungus. The purified enzyme was obtained from 1.7l stationary culture filtrate, with 4.2% recovery, and showed a single protein band on SDS-PAGE. The molecular mass was about 25kDa. The enzyme was most active at around 40°C and pH 5.0 and stable over pH 4.5–6.5 for 30min at 37°C. This amylase was remarkably activated by the presence of Ca²⁺ ion (7.7 times that of the control), but Ba²⁺ and Ag⁺ completely inhibited the activity. The amylase readily hydrolyzed the -1,4 glucosidic linkage such as dextrin and amylose A (MW, 2900), converting into glucose, and hydrolyzed the -1,6 glucosidic linkage of isomaltohexaose and amylopectin. However, the enzyme did not hydrolyze the cyclic polysaccharides. On the other hand, when a low molecular mass amylose A was hydrolyzed by this amylase, -anomer glucose was produced. From these results, we concluded that the amylase from L. shimeji seems to be a glucoamylase.     

<Emphasis Type="Italic">In vitro</Emphasis> screening of sugarcane to evaluate smut susceptibility

Tissue-cultured plantlets of three sugarcane (Saccharum spp.) cultivars having a known field smut reaction were screened for susceptibility to Ustilago scitaminea H&P Sydow. Plantlets were inoculated with 0.5 l of a suspension of equally mixed quantities of plus and minus mating type sporidia of U. scitaminea at concentrations ranging from 1×10¹ to 1×10⁶ cells. Fungal sori (whips) were produced in cultivar N12 (intermediate) 6weeks following inoculation with 1×10⁵ mixed sporidia and thereafter in cultivar NCo310 (susceptible) but not in cultivar N19 (resistant). Sori bearing teliospores were produced up to 3months following inoculation and incubation at 26°C. No sori were produced at mixed sporidial concentrations lower than 1×10⁵cells. The in vitro soral production in cultivars N19, N12 and NCo310 was 0, 27.5 and 47.5% respectively. Plantlets inoculated with 1×105sporidia of only one mating-type did not produce sori in any of the three cultivars tested. Blind scoring of an unknown sugarcane cultivar by this method corresponded exactly with its field smut rating.     

The Effect of Salicylic Acid on Peroxidase Activity in Wheat Calli Cocultured with the Bunt Pathogen Tilletia caries

The effect of salicylic acid (SA) on peroxidase activity in wheat (Triticum aestivum L.) calli cocultured with the bunt pathogen Tilletia caries was studied. Fungal infection was shown to activate cytoplasmic peroxidase. SA suppressed total peroxidase activity but did not inhibit the peroxidase with pI 9.8. A novel chitin-specific peroxidase with pI 3.5 appeared after the SA treatment. The infection of SA-treated cells with Tilletia caries activated the isoenzymes with pI 3.5, 4.8, and 7.5 and stimulated their secretion into the culture medium. The ability of SA to control wheat peroxidase activity during pathogenesis is discussed. The important role of this control in plant defense responses to the bunt pathogen is emphasized.     

Improved long-term cryostorage of Escherichia colicompetent cells using trehalose

Trehalose added to storage buffers for chemical-induced transformations at 200 mm increased the survival of Escherichia coli competent cells 1.34.8-fold over 180 d cryostorage compared with dimethyl sulfoxide or glycerol.     

SelectingRhizobium phaseoli strains for use with beans (Phaseolus vulgaris L.) in Kenya: Tolerance of high temperature and antibiotic resistance

Forty one strains ofRhizobium phaseoli were screened for the ability to multiply at high temperatures on yeast extract-mannitol agar. Most strains were tolerant of 30°C, eight strains were tolerant of 45°C and two of 47°C although the rate of multiplication was reduced at 45–47°C. The high temperature-tolerant strains were isolated from Kenyan soils and were fast-growing. Seven of the eight strains tolerant of 45–47°C lost their infectiveness after incubation at high temperature but four strains tolerant of 40°C remained infective after incubation at that temperature.Thirty six strains were resistant to 200 g ml^–1 streptomycin sulphate and 29 strains to 200 g ml^–1 spectinomycin dihydrochloride. Eight strains were resistant to both antibiotics each at 200 g ml^–1. Two of the double-labelled antibiotic-resistant mutants lost their infectiveness onPhaseolus vulgaris. The response to acidity was unaltered and two of the mutants showed a decrease in temperature tolerance. The doublelabelled mutants were recoverable from two Kenyan soils.