Die Struktur des samenableitenden Gangsystems bei Geophilus linearis Koch (Chilopoda)

Zusammenfassung Die männlichen Genitalwege von Geophilus linearis wurden licht- und elektronenmikroskopisch untersucht.Der schon makroskopisch sichtbaren Unterteilung des ableitenden Gangsystems in Vasa efferentia, dünnen und dicken Teil des Vas deferens entspricht die histologische Differenzierung ihres in allen drei Abschnitten einreihigen Epithels. Dem Epithel liegt außen eine auffallend dicke Basalmembran auf, die von einer meist einschichtigen Lage quergestreifter Muskulatur umgeben wird.Die Vasa efferentia sind durch hohe regelmäßige Einfaltungen der basalen Zellmembran, einen besonderen Mitochondrienreichtum und einen dichten Mikrovillibesatz charakterisiert. Der dünne Teil des Vas deferens fällt durch seine seitlichen Zellverzahnungen, die besondere apikale Zellbegrenzung in Form von Stereozilien und Zytoplasmaprotrusionen als Zeichen einer Sekretion auf. Der dicke Teil des Vas deferens zeichnet sich durch den Reichtum seiner Zellen an Organellen, vor allem Golgikomplexen und Ergastoplasma, aus. Die immer vorhandenen großen Mengen an Sekret im Lumen müssen damit in Zusammenhang stehen, obwohl deutliche Zeichen einer Sekretion in diesem Gangabschnitt nicht nachweisbar sind.

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The structure of the male genital ducts of Geophilus linearis Koch (Chilopoda)

Summary The male genital ducts of Geophilus linearis have been studied by means of light and electron microscopy.The subdivision of the ducts into vasa efferentia, a thin and a thick part of the vas deferens can be seen macroscopically and is confirmed by the microscopic results: a simple epithelium is surrounded by an extraordinary thick basement membrane and a very thin layer of striated muscles.The vasa efferentia are characterized by high regular folds of the basal cell membrane, richness of mitochondria, and a tight border of microvilli. The thin part of the vas deferens ist striking by the lateral interdigitations between the cells and their special apical limitation, stereocilia and cytoplasmic protrusions as symptoms of secretion. The thick part of the vas deferens is distinguished by a particular abundance of cell organelles, especially Golgi complexes and ergastoplasm. The great quantity of secretory products, always existing in the lumen, must be in correlation with these organelles although an evident secretory process cannot be demonstrated.

     

The in vitro production of an anthocyanin from callus cultures of Oxalis linearis

Callus growth and the production of anthocyanins were sustained on the salts and vitamins of Murashige and Skoog. Callus growth was stimulated at a concentration of 8–32 M -naphthaleneacetic acid (NAA) and 2,4-dichlorophenoxyacetic acid (2,4-d). Benzyladenine (BA) and zeatin at 8 M inhibited callus growth whereas isopentenyladenine (iP) stimulated callus growth. NAA repressed anthocyanin production with an increase in NAA from 8–32 M. Anthocyanin synthesis was promoted by an increase in 2,4-d from 0.5 to 2 M and decreased thereafter up to a concentration 32 M 2,4-d. A concentration of 8 M BA, thidiazuron and zeatin, respectively stimulated pigment production. Sucrose stimulated callus growth at 60 mM and pigment production at 120–360 mM.Abbreviations BA 6-benzyladenine - 2,4-d 2,4-dichlorophenoxyacetic acid - NAA -naphthaleneacetic acid - iP isopentenyladenine - TZ thidiazuron-N-phenyl-N-1,2,3-thiadiazol-5-yl-urea - Bu-HCl Butanol-2N HCl - BAW Butanol-acetic acid-water     

The effects of floral display on pollinator visitation vary among populations ofPhacelia linearis (Hydrophyllaceae)

Summary Individual plants in gynodioecious populations ofPhacelia linearis (Hydrophyllaceae) vary in flower gender, flower size, and flower number. This paper reports the effects of variation in floral display on the visitation behaviour of this species' pollinators (mainly pollen-collecting solitary bees) in several natural and three experimental plant populations, and discusses the results in terms of the consequences for plant fitness. The working hypotheses were: (1) that because female plants do not produce pollen, pollen-collecting insects would visit hermaphrodite plants at a higher rate than female plants and would visit more flowers per hermaphrodite than per female; and (2) that pollinator arrival rate would increase with flower size and flower number, the two main components of visual display. These hypotheses were generally supported, but the effects of floral display on pollinator visitation varied substantially among plant populations. Hermaphrodites received significantly higher rates of pollinator arrivals and significantly higher rates of visits to flowers than did females in all experimental populations. Flower size affected arrival rate and flower visit rate positively in natural populations and in two of the three experimental populations. The flower size effect was significant only among female plants in one experimental population, and only among hermaphrodites in another. The effect of flower number on arrival rate was positive and highly significant in natural populations and in all experimental populations. In two out of three experimental populations, insects visited significantly more flowers per hermaphrodite than per female and visited more flowers on many-flowered plants than on few-flowered plants, but neither effect was detected in the third experimental population. Because seed production is not pollen-limited in this species, variation in pollinator visitation behaviour should mainly affect the male reproductive success of hermaphrodite plants. These findings suggest that pollinator-mediated natural selection for floral display inP. linearis varies in space and time.     

Zur Lebensgeschichte der DiatomeeAchnanthes linearis und Bemerkungen über andereAchnanthes-Arten

Achnanthes linearis produces two auxospores from one cell pair by allogamic fusion of migratory and stationary gametes. Unusually little copulation jelly is produced. Pairing occurs by chance in regard to the heteropoly of the transapical axis. The orientation of the primary cells in relation to the substratum and to the mother cells is constant and characteristic. Variation of cell size is much larger than hitherto known; correspondingly the diagnosis is to be completed.—The position and orientation of vegetative cells and partner cells is strongly determined by the relief of the leaves ofFontinalis on which they are fixed with their raphe valve. The same is true for the cells ofA. minutissima which usually are fixed at one cell pole only, but exceptionally at both poles; this means that morphological heteropoly of apical axis is lacking, and that the function of the second holdfast-jelly producing structure usually is suppressed. The cells of both species normally creep by means of the raphe mechanism; the direction is very independent of the relief of theFontinalis leaves. After cell division the moving down of the upper daughter cell follows a different mechanism.A. linearis is the first to settle onFontinalis leaves, other epiphytes come much later.

     

Structural differences between light and heavy rare earth elment binding chlorophylls in naturally grown fern Dicranopteris linearis

Chloroplasts and chlorophylls were isolated from the leaves of Dicranopteris linearis, a natural perennial fern sampled at rare earth element (REE) mining areas in the South-Jiangxi region (southern China). The inductively coupled plasma-mass spectrometry (ICP-MS) results indicated that REEs were present in the chloroplasts and chlorophylls of D. linearis. The in vivo coordination environment of light REE (lanthanum) or heavy REE (yttrium) ions in D. linearis chlorophyll-a was determind by the extended X-ray absorption fine structure (EXAFS). Results revealed that there were eight nitrogen atoms in the first coordination shell of the lanthanum atom, whereas there were four nitrogen atoms in the first coordination shell of yttrium. It was postulated that the lanthanum-chlorophyll-a complex might have a double-layer sandwichlike structure, but yttrium-binding chlorophyll-a might be in a single-layer form. Because the content of REE-binding chlorophylls in D. linearis chlorophylls was very low, it is impossible to obtain structural characteristics of REE-binding chlorophylls by direct analysis of the Fourier transform infrared (FTIR) and ultraviolet (UV)-visible spectra of D. linearis chlorophylls. In order to acquire more structural information of REE-binding chlorophyll-a in D. linearis, lanthanum—and yttrium-chlorophyll-a complexes were in vitro synthesized in acetone solution. Element analyses and EXAFS results indicated that REE ions (lanthanum or yttrium) of REE-chlorophyll-a possessed the same coordination environment whether in vivo or in vitro. The FTIR spectra of the REE-chlorophyll-a complexes indicated that REEs were bound to the porphyrin rings of chlorophylls. UV-visible results showed that the intensity ratios of Soret to the Q-band of REE-chlorophyll-a complexes were higher than those of standard chlorophyll-a and pheophytin-a indicating that REE-chlorophyll-a might have a much stronger ability to absorb the ultraviolet light. The MCD spectrum in the Soret band region of lanthanum-chlorophyll-a showed a special peak, but yttrium-chlorophyll-a did not have this special peak, corresponding well to their double-layer and single-layer structure, respectively. Structural differences between lanthanum—and yttrium-chlorophyll-a might result from the difference in ion radius between yttrium and lanthanum. These data might be useful for understanding of both the properties of REE-chlorophyll-a complexes and the physiological roles of REEs in the hyperaccumulator D. linearis.     

A comparative study on the antimutagenic properties of aqueous extracts of Aspalathus linearis (rooibos), different Cyclopia spp. (honeybush) and Camellia sinensis teas

Antimutagenic activity of aqueous extracts of the South African herbal teas, Aspalathus linearis (rooibos) and Cyclopia spp. (honeybush) was compared with that of Camellia sinensis (black, oolong and green) teas in the Salmonella mutagenicity assay using aflatoxin B₁ (AFB₁) and 2-acetylaminofluorene (2-AAF) as mutagens. The present study presents the first investigation on antimutagenic properties of C. subternata, C. genistoides and C. sessiliflora. The herbal teas demonstrated protection against both mutagens in the presence of metabolic activation, with the exception of “unfermented” (green/unoxidised) C. genistoides against 2-AAF, which either protected or enhanced mutagenesis depending on the concentration. Antimutagenic activity of “fermented” (oxidised) rooibos was significantly (P < 0.05) less than that of Camellia sinensis teas against AFB₁, while for 2-AAF it was less (P < 0.05) than that of black tea and similar (P > 0.05) to that of oolong and green teas. Antimutagenic activity of unfermented C. intermedia and C. subternata exhibited a similar protection as fermented rooibos against AFB₁. Against 2-AAF, fermented rooibos exhibited similar protective properties than unfermented C. intermedia and C. sessiliflora. Unfermented rooibos was less effective than the C. sinensis teas and fermented rooibos, but had similar (P > 0.05) antimutagenicity to that of fermented C. sessiliflora against AFB₁ and fermented C. subternata against 2-AAF. Fermented C. intermedia and C. genistoides exhibited the lowest protective effect against 2-AAF, while fermented C. intermedia exhibited the lowest protection when utilising AFB₁ as mutagen. Aspalathin and mangiferin, major polyphenols in rooibos and Cyclopia spp., respectively, exhibited weak to moderate protective effects when compared to the major green tea catechin, (−)epigallocatechin gallate (EGCG). Antimutagenic activity of selected herbal tea phenolic compounds indicated that they contribute towards (i) observed antimutagenic activity of the aqueous extracts against both mutagens and (ii) enhancement of the mutagenicity of 2-AAF by unfermented C. genistoides. Antimutagenic activity of the South African herbal teas was mutagen-specific, affected by fermentation and plant material, presumably due to changes and variation in phenolic composition.     

Diterpenes from the brown algae Dictyota dichotoma and Dictyota linearis

Nineteen secondary metabolites of the brown alga Dictyota dichotoma (Huds.) Lam. and fifteen metabolites of the brown alga D. linearis (Ag.) Grev. were isolated and their chemical structures were elucidated on the basis of their NMR and mass spectral data. The diterpenes isopachydictyolal (1) from D. dichotoma and 4alpha-acetyldictyodial (2) from D. linearis are new natural products. The antiviral activity of metabolites isolated in adequate amounts was evaluated in laboratory assays against Herpes simplex virus I (HSV I) and Poliomyelitis Virus I, using Vero cells as hosts.     

Secondary transmission of a nuclear polyhedrosis virus ofNeodiprion taedae linearis [Hym.: Diprionidae] between larval colonies on loblolly pine

Transmission of a nuclear polyhedrosis virus (NtNPV) of the loblolly pine sawfly,Neodiprion taedae linearis Ross was examined in larval populations on loblolly pine. NtNPV infection of larvae in one colony resulted in transmission to other colonies in the tree. Mortality in untreated colonies was highest when the treated and untreated colonies were located in the upper canopy and when small larvae were treated with virus (42.6–61.9%). Levels of mortality from NtNPV in the untreated colonies were low (2.8–25.0%) when the treated colony was located low in the canopy. Larvae from untreated colonies in the tree were usually large at death. Mortality in untreated larval colonies collected from nearby trees was much less (0.0–27.7%) than that in the trees containing the treated colony. Published with the approval of the Director, Arkansas Agricultural Experiment Station. Use of a trade name does not imply endorsement or guarantee of the product or the exclusion of other products of similar nature.     

A simple procedure for polymerase chain reaction of the PSBA gene in algae: application to the screening of mutations conferring atrazine resistance and discrimination of natural populations of Porphyra linearis

A simplified procedure is described for polymerase chain reaction (PCR) of a partial sequence (bp 601–893) of the plastid gene psbA in the rhodophyte Porphyra linearis and the diatoms Haslea ostreria and Skeletonema costatum. This procedure involves the use of all tissues of P. linearis and live cell suspensions of H. ostreria or S. costatum as DNA templates, without any further purification of DNA. As in the case of PCR with DNA extracts, a single major band of the expected size (292 bp) was obtained after PCR for the three species. Sequences of the amplified fragments were aligned, confirming that the amplified products were part of the psbA gene. The method was then used to screen mutations in partial psbA genes of 23 samples of P. linearis collected at four different stations along the mid-Atlantic coast of France. An alignment was obtained indicating the existence of mutations, though not in codons known for herbicide resistance. All mutations found were silent. However, genetic polymorphism discriminated between samples collected from two stations. The method employed allows rapid amplification of the herbicide target gene and simplifies the procedure for screening mutations or populations in algae. Its application to other genes and species is considered.     

Responses of Porphyra linearis (Rhodophyta) to environmental factors under controlled culture conditions

The effect of environmental parameters on the growthof Porphyra linearis gametophytes was examinedunder controlled conditions, and related to themultilinear regression growth model recently developedfor this seaweed under coastal conditions in theeastern Mediterranean. Growth chambers, a gradienttable, special culture devices and analytical methodswere combined for this culture study.The major factors significantly controlling thegrowth rate of the P. linearis gametophytein glass dishes were: photoperiod, temperature, agein culture, photosynthetic photon flux (PPF), salinityand water dynamics. Maximal growth occurred underdaylength of 12 h, medium temperature (15–20 ^°C), low PPF (70–140 mol photon m^-2s^-1), ambient salinity (30–40 ppt), 1–3 h ofdaily air exposure, and water velocity of 4 cm s^-1.Photosynthesis and respiration rates weredominantly affected by daylength and temperature,while the concentration of pigments was dominantlyaffected by PPF and temperature.These conditions correspond well to the optimalnatural growth environment of this local species andare in agreement with the optimum estimated throughthe recently developed outdoor mathematical growthmodel.     

Protoplast production fromPorphyra linearis using a simplified agarase procedure capable of commercial application

Abalone enzymes, Cellulase R-10, Macerozyme and agarase fromPseudomonas atlantica were tested for activity on agarose, cellulose, xylan, the cell wall matrix and porphyran isolated fromPorphyra linearis. Agarase, and to a lesser extent Macerozyme, digested both agarose and porphyran. Abalone enzymes and Cellulase R-10 reacted only weakly with porphyran. A simple standardized protocol for making protoplasts fromPorphyra linearis was developed using 0.025% agarase in seawater without added organic osmoticants. Protoplasts prepared with agarase remained viable for at least 24 h in the digestion medium. Regeneration of the protoplasts followed the normal pattern for this species. Agarase can be used to obtain large number of protoplasts which could substitute for conchospores in seeding nets for the aquaculture ofP. linearis Author for correspondenceIssued as NRCC no. 34897     

Rooibos (Aspalathus linearis) beyond the farm gate: From herbal tea to potential phytopharmaceutical

Aspalathus linearis (Burm.f.) Dahlg. (Fabaceae, Tribe Crotalarieae), an endemic South African fynbos species, is cultivated to produce the well-known herbal tea, rooibos. It is currently sold in more than 37 countries with Germany, the Netherlands, the United Kingdom, Japan and the United States of America representing 86% of the export market in 2010. Its caffeine-free and comparatively low tannin status, combined with its potential health-promoting properties, most notably antioxidant activity, contributes to its popularity. First marketed in 1904 in its fermented (oxidised) form, green rooibos is a new product recently on the market. The utilisation of rooibos has also moved beyond a herbal tea to intermediate value-added products such as extracts for the beverage, food, nutraceutical and cosmetic markets. Its potential as a phytopharmaceutical, shown in recent scientific studies, has not yet been exploited. This review focuses on past and current research aimed at enhancing the value of rooibos herbal tea as a specialised, niche product and expanding its value-adding potential against the background of its traditional use and the current market. The focus falls specifically on aspects such as composition, processing, quality and rooibos as food and potential medicine.     

Robertsonian differentiation and preferential pairing revealed in species and F1 hybrids of theGibasis linearis group (Commelinaceae)

Three closely related species of theG. linearis group are differentiated by their basic numbers and ploidy levels. The change in basic number involves Robertsonian fusion, but the species also differ by interchange and cryptic structural changes revealed by meiotic pairing in F₁ hybrids.Chromosome Evolution in theGibasis linearis Group (Commelinaceae), II.—Part I:Kenton (1981a).     

Experimental investigation on weather cues for mast seeding of Fagus crenata

Although a recent study has suggested that the minimum temperature from late April to mid-May in the year preceding flowering causes mast seeding in Fagus crenata, no direct evidence is available to support this finding. The aim of the present investigation was, therefore, to test – in a field experiment – whether the minimum temperature determines mast seeding in F. crenata. We examined the effect of nighttime temperatures on flower-bud initiation in F. crenata by enclosing fruit-bearing branches in heated bags at night, thereby maintaining average nighttime temperatures of approximately 2°C above the ambient temperatures. Heating was applied at night from 21 April to 20 May, 21 May to 19 June, and 21 April to 19 June in 2001. Female inflorescence initiation was inhibited by the nocturnal heating in the period 21 April to 20 May and 21 May to 19 June. However, nocturnal heating from 21 April to 20 May was the more important based on the odds ratio of the former being much lower than that of the latter in a logistic regression model. Male inflorescence initiation was also inhibited by nocturnal heating from 21 April to 20 May. We therefore conclude that flower-bud initiation in F. crenata was controlled by nighttime temperatures between 21 April and 20 May.     

Evolution of dark-spored Myxomycetes (slime-molds): molecules versus morphology

The Myxomycetes are a major component of soil amoebae, displaying a complex life cycle that terminates in the formation of often macroscopic fruiting bodies. The classification of Myxomycetes is controversial and strongly depends on the weight given by different authors to morphological and developmental characters. We used a molecular approach to establish the phylogenetic relationships in the dark-spored orders Stemonitales and Physarales. Twenty-five small subunit ribosomal RNA gene sequences were obtained, with focus on two Stemonitales genera, Lamproderma and Comatricha. Unexpectedly, our results show that Stemonitales are paraphyletic with Physarales arising from within a Lamproderma clade. The genus Lamproderma itself is polyphyletic and can be divided into two distinct clades. Additionally, we found that Comatricha nigricapillitia comprises two cryptic species, both related to Enerthenema. Our study allows the reappraisal of morphological and developmental characters in the light of molecular data and sets foundations for a new classification of Myxomycetes.     

Zur Evolution des Parasitismus bei denScrophulariaceae undOrobanchaceae

Different growth forms and life forms of parasitic plants inScrophulariaceae andOrobanchaceae were studied from a comparative point of view. The most primitive form of parasitism is found in small, annual root parasites. Small wart-haustoria in the hypocotylar region of larger root parasites point towards a tendency of these plants to form hypocotylar tubercles as primary haustoria. Wart-haustoria also can develop on scale leaves, demonstrating an evolutionary trend towards the most advanced form of parasitism in these two families the formation of large leaf haustoria.

     

Photosynthetic inorganic carbon utilization and growth of Porphyra linearis (Rhodophyta)

Photosynthetic (oxygen evolution) and growth (biomass increase) responses to ambient pH and inorganic carbon (Ci) supply were determined for Porphyralinearis grown in 0.5 L glass cylinders in the laboratory, or in 40 L fibreglass outdoor tanks with running seawater. While net photosynthetic rates were uniform at pH 6.0–8.0, dropping only at pH 8.7, growth rates were significantly affected by pH levels other than that of seawater (c. pH 8.3). In glass cylinders, weekly growth rates averaged 76% at external pH 8.0, 13% at pH 8.7 and 26% at pH 7.0. Photosynthetic O₂ evolution on a daily basis(i.e. total O₂ evolved during day time less total O₂ consumed during night time) was similar to the growth responses at all experimental pH levels, apparently due to high dark respiration rates measured at acidic pH. Weekly growth rates averaged 53% in algae grown in fibreglass tanks aerated with regular air (360 mg L_-1 CO₂) and 28% in algae grown in tanks aerated with CO₂-enriched air (750 mg L^-1 CO₂). The pH of the seawater medium in which P. linear is was grown increased slightly during the day and only rarely reached 9.0. The pH at the boundary layer of algae submerged in seawater increased in response to light reaching, about pH 8.9 within minutes, or remained unchanged for algae submerged in a CO₂-free artificial sea water medium. Photosynthesis of P. linearissaturated at Ci concentrations of seawater (K_0.5560 μM at pH 8.2) and showed low photosynthetic affinity for CO₂(K_0.5 61 μM) at pH 6.0. It is therefore concluded that P. linearisuses primarily CO₂ with HCO₃ ^- being an alternative source of Ci for photosynthesis. Its fast growth could be related to the enzyme carbonic anhydrase whose activity was detected intra- and extracellularly. This revised version was published online in August 2006 with corrections to the Cover Date.     

Switching from negative to positive density-dependence among populations of a cobble beach plant

Understanding the co-occurrence of ecologically similar species remains a puzzling issue in community ecology. The species-rich mouse lemurs (Microcebus spec.) are distributed over nearly all remaining forest areas of Madagascar with a high variability in species distribution patterns. Locally, many congeneric species pairs seem to co-occur, but only little detailed information on spatial patterns is available. Here, we present the results of an intensive capture-mark-recapture study of sympatric Microcebus berthae and M. murinus populations that revealed small-scale mutual spatial exclusion. Nearest neighbour analysis indicated a spatial aggregation in Microcebus murinus but not in M. berthae. Although the diet of both species differed in proportions of food categories, they used the same food sources and had high feeding niche overlap. Also, forest structure related to the spatial distribution of main food sources did not explain spatial segregation because parts used by each species exclusively did not differ in density of trees, dead wood and lianas. We propose that life history trade-offs that result in species aggregation and a relative increase in the strength of intra-specific over inter-specific competition best explain the observed pattern of co-occurrence of ecologically similar congeneric Microcebus species.