KARYOLOGY OF BANGIA ATROPURPUREA (RHODOPHYTA,BANGIALES) FROM MEDITERRANEAN AND NORTHEASTERN ATLANTIC POPULATIONS1

We studied the karyology of Bangia atropurpurea (Roth) C. Ag. collected from marine and freshwater populations from the Mediterranean region and some northeastern Atlantic localities. Gametophytic thalli had two haploid karyotypes, n = 3 and n = 4. The n = 4 karyotype was only occasionally present in the Mediterranean and was also found in one Atlantic population, confirming a previous report. We propose that the four-chromosome karyotype is an aneuploid form, n + 1. Chromosomes were frequently observed either in a parallel arrangement or in a circular configuration.     

Fine‐Scale Spatial Patterns of Mature and Immature Filaments and Bioorganic Compounds of the Rhodophyte Bangia atropurpurea in the Supra‐ and Eulittoral Zones of a Large Lake1

Bangia atropurpurea (Mertens ex Roth) C. Agardh is a freshwater red alga species that is distributed worldwide. B. atropurpurea is highly adaptable due to its stress‐tolerance, which ensures survival under desiccation periods and under radiation extremes typical of the supra‐ and upper eulittoral zones. Whereas a number of previous investigations addressed some of the physiological and biochemical traits involved in stress‐tolerance, we studied the spatial arrangement of the mature (multiseriate) and immature (uniseriate) filaments and of selected bioorganic compounds along a gradient defined by distance from the waterline. Substantial physiological and biochemical differences were previously observed among phenological stages in the marine environment. In this study, we showed a nonrandom spatial structure of both phenological stages and photosynthetic pigments and photoprotective compounds, R‐phycocyanin and R‐phycoerythrin along the supralittoral‐eulittoral gradient. This observed pattern strongly suggests a complex interplay between physio‐morphological regulation and spatial arrangement of mature and immature filaments in conferring the typical stress tolerance of B. atropurpurea.     

The cell wall chemistry of Bangia atropurpurea (Bangiales, Rhodophyta) and Bostrychia moritziana (Ceramiales, Rhodophyta) from marine and freshwater environments

The cell wall polysaccharides of two species of red algae, which are adapted to both freshwater and marine environments, were analysed to determine the effect of these widely different environments on their commercially important agarocolloids and to investigate the possible role of the cell wall in environmental adaptation. Cell wall polymers of freshwater isolates of Bangia atropurpurea (Roth) C. Agardh and cultured freshwater and marine Bostrychia moritziana (Sonder ex Kützing) J. Agardh were isolated and the polysaccharides chemically fractionated and characterized. Wall polysaccharides of freshwater B. atropurpurea were similar to those previously reported for marine isolates with repeating disac-charide units of agarose and porphyran predominant in the hot water extracts. In the insoluble residues, 3-iinked galactosyl and 4-linked mannosyl residues were predominant. Bostrychia moritziana wall polysaccharides included agarocolloids with various patterns of methyl ether substitution similar to those previously described for other Ceramiales. Differences in the position of methyl ether substituents were detected in the hot water extracts of the freshwater and marine specimens. Polymers of freshwater ß. moritziana cultures were composed of a complex mixture of repeating disaccharide units including 2′-O-methyl agarose, 6-O-methyI agarose and 2′-O-methyl porphyran. Polymers of marine isolates of ß. moritziana differ in that they contain only trace amounts of 2-O-methyl saccharides and increased amounts of 6-O-amethyl saccharides. The hot water insoluble residues of both freshwater and marine isolates of ß. moritziana contain a mixture of 3-linked galactosyl and 4-linked glucosyl residues. These results indicate that the adaptive response of B. moritziana to changing osmotic and ionic conditions may include changes in cell wall chemistry: notably, the pattern of methyl ether substitution.     

A preliminary investigation of the order Bangiales (Bangiophycidae, Rhodophyta) based on sequences of nuclear small-subunit ribosomal RNA genes

We investigated phylogenetic relationships among red algae of the order Bangiales by analysis of sequences of the nuclear gene encoding cytosolic small-subunit ribosomal RNA in Bangia atropurpurea (Roth) C. Ag. and eight samples representing seven species of Porphyra. The ssu-rDNA range from 1818 to 1845 nucleotides in length, with guanosine plus cytosine ratios between 47.0% and 48.6%. A group IC1 intron occurs in the B atropurpurea ssu-rDNAs at the same position as in P. spiralis var. amplifolia Oliveira Filho et Coll and several other eukaryote ssu-rDNAs. The nine sequences form a stable monophyletic group upon phylogenetic analysis. The ssu-rDNA from B. atropurpurea nests stably within the Porphyra group and is closely related to P. amplissima (Kjellm.) Setchell et Hus in Hus, making the genus Porphyra paraphyletic. No correlation is seen between phylogenetic position and number of cell layers in the Porphyra thallus. We discuss possible taxonomic and evolutionary implications of these observations.     

ISOLATION AND REGENERATION OF HAPLOID PROTOPLASTS FROM BANGIA ATROPURPUREA (RHODOPHYTA) WITH MARINE BACTERIAL ENZYMES1

Three kinds of enzymes, agarase, β-1,4-mannanase, and β-1,3-xylanase, required for isolation of protoplasts from the red alga Bangia atropurpurea (Roth) C. Ag. were prepared from bacterial culture fluids of Vibrio sp. PO-303, Vibrio sp. MA-138, and Alcaligenes sp. XY-234, respectively, isolated from the sea environment. The optimal pH of all enzymes was around 7.5. Suitable conditions for protoplast isolation from B. atropurpurea were examined. The pretreatment of the fronds with pa-pain solution (20 mM Mes buffer, pH 7.5, containing 2% papain and 0.5 M mannitol) contributed to successful protoplast isolation. When razor-cut fragments of the fronds (about 200 mg in fresh weight) immersed in 20 mM Mes buffer, 7.5, containing 0.5 M mannitol and one unit each of agarase, β-1,4-mannanase, and β-1,3-xylanase were incubated at 22°C for 90 min with gentle agitation, 5.7 × 10⁶ protoplasts were released from them. Many protoplasts regenerated into fronds of regular or irregular shape.     

pEffects of UV radiation on the ultrastructure of several red algae

The effect of ultraviolet (UV) radiation on the ultrastructure of four red algae, the endemic Antarctic Palmaria decipiens (Reinsch) Ricker and Phycodrys austrogeorgica Skottsberg, the Arctic‐cold temperate Palmaria palmata (Linnaeus) O. Kuntze and the cosmopolitan Bangia atropurpurea (Roth) C. Agardh was studied. All four species showed a formation of ‘inside‐out’ vesicles from the chloroplast thylakoids upon exposure to artificial UV‐radiation. In P. decipiens, most vesicles were developed after 8 h and in P. palmata, after 48 h of UV exposure. In B. atropurpurea, vesi‐culation of thylakoids was observed after 72 h of UV irradiation. In Ph. austrogeorgica, the chloroplast envelope and thylakoid membranes were damaged and the phycobilisomes became detached from the thylakoids after 12 h of UV exposure. Ultraviolet‐induced changes in the membrane structure of mitochondria were observed in P. decipiens and P. palmata. However, in P. decipiens they were reversible as was the damage in chloroplast fine structure after 12 h of UV treatment. Protein crystals in Ph. austrogeorgica showed degradation after exposure to UV radiation. Different methods of fixation and embedding macroalgal material are discussed. These findings give insight into the fine structural changes which occur during and after UV exposure and indicate a relationship between the species dependent sensitivity to UV‐exposure and the depth distribution of the different species.     

LIGHT REQUIREMENTS FOR MONOSPORE GERMINATION IN BANGIA ATROPURPUREA (RHODOPHYTA)1

Monospore germination, in Bangia atropurpurea (Roth) C. Ag. [= B. fuscopurpurea (Dillw.) Lyngb.] is light-dependent. In white light, the percent germination increases with increasing photon fluence rate until the response is saturated at 35 μmol · m^?2· s^?1. At a saturating photon fluence rate in an 18:6 h L:D cycle, 9 days are required for maximum germination. Green light is the most effective spectral region for monospore germination, although the process can occur in red and blue light if sufficiently high photon fluence rates are provided. Monospore germination and photosynthetic oxygen evolution are completely inhibited by DCMU at a concentration of 1 × 10^?6 M. Germination is reduced in a low CO₂ atmosphere and does not occur in the dark when glucose, maltose or inositol are supplied. It is concluded that photosynthesis is required for monospore germination.     

149 Distribution and Invasion of Bangia Atropurpurea (Rhodophyta) in the Laurentian Great Lakes

Müller et al. (1998) noted that freshwater collections of the genus Bangia formed a distinct group separate from marine entities in gene sequence analyses. Recently, the species epithet B. atropurpurea has been resurrected to represent this freshwater lineage. This taxon is one of many invasive species within the Laurentian Great Lakes. B. atropurpurea was first observed in Lake Erie in 1964 and by 1982 was observed in all of the Great lakes except Lake Superior. The present study was initiated to examine the further spread of B. atropurpurea and determine the origin of these populations. Hence, a survey of all the Great Lakes was conducted in 1995 (86 sites) and again in 2002 (104 sites). Bangia was observed at 43 sites in 1995 and 39 sites in 2002. For the first time, this alga has been observed to be present in the St. Lawrence River (1995), Georgian Bay on Lake Huron (2002) and Lake Simcoe (eastern shore, 2002) and hence this alga appears to be spreading into new locations. Cluster analyses of morphological data reveal three distinct groupings that do not separate according to location or lake basin. Preliminary analyses of ITS 1 and 2 sequences show differences among samples within Lake Ontario and among all Lakes; however, collections from Lake Simcoe are very similar in sequence. We are continuing to examine the relationship of Great Lakes populations with freshwater collections from Europe.     

DISTRIBUTION AND SALINITY ADAPTATIONS OF BANGIA ATROPURPUREA (RHODOPHYTA), A PUTATIVE MIGRANT INTO THE LAURENTIAN GREAT LAKES1

In a survey of the distribution of Bangia atropurpurea (Roth) Ag. along the north and east shorelines of the Laurentian Great Lakes, it was observed that this species was concentrated in the lower lakes. Asexual reproduction by monospore formation was the only form of reproduction in these populations. First generation germlings derived from these spores grew in a wide range of salinities from 1 to 26‰, but the rate was inversely proportional to salinity. In addition, acclimation of parent plants to freshwater or marine media prior to sporulation affected growth rates of first generation germlings placed into a series of salinities. By the second and third generation, germlings with a lineage of seawater showed a preference for the higher salinities, 19 and 26‰ Plants collected in Lake Ontario exhibited no decline in photosynthetic rate as salinity was raised by 13‰ for 15 min. At 26‰ the rate was reduced by half and thylakoids were disrupted in the region of the pyrenoid. On the other hand, third generation plants with a history of seawater attained maximum photosynthetic rates at 26‰ and contained a normal thylakoid organization. Three chromosomes were observed in these plants, which agrees with some of the previous findings for marine Bangia. Origins and taxonomic status of Bangia growing In the Great Lakes are discussed in light of these findings.     

Dynamics of Escherichia coli at elevated temperatures: effect of temperature history and medium

Aims: The dynamics of Escherichia coli near the maximum temperature for growth in a rich medium are analysed. The effects of temperature history, medium composition and physiological state of the inoculum are evaluated. Methods and Results: Kinetics of E. coli K12 MG1655 is studied in ‘brain–heart infusion’ broth in a temperature controlled environment. Based on viable counts, ‘smooth’ growth curves are observed at 40, 41, 42 and 43°C. The exponential growth phase at 44 and 45°C is interrupted. At 46°C, a period of exponential growth is followed by inactivation. Neither the physiological state of the inoculum nor medium enrichment alters the dynamics, whilst temperature pre‐adaptation or chemical chaperones restore regular cell growth and division (‘smooth’ exponential growth). Conclusions: Atypical, nonexponential growth at 44, 45 and 46°C seems related to protein destabilization and can (partly) be restored by an appropriate medium design (i.e. addition of chemical chaperones) or temperature history (i.e. selection of a more resistant subpopulation). Significance and Impact of the Study: This study indicates that the maximum temperature for growth is dependent on the temperature history and the chemical environment. These observations and the nonexponential kinetics have important implications for the development of predictive models for food safety and quality.     

Growth interactions between calli and explants of rose plants in vitro

Growth of explants or calli of two rose cultivars ‘Sonia’ and ‘Golden Times’, was extensively promoted when they were grown on agar together with calli of rose rootstocks Rosa indica or Rosa canina, while growth of callus of a miniature rose cultivar was either not affected or inhibited. The growth of R. indica callus was inhibited when accompanied by explants of ‘Sonia’ or ‘Golden Times’. Promotion or inhibition of explants or callus growth was also observed when the agar medium was supplemented with conditioned liquid medium from cell suspension cultures of cv. Sonia or R. indica. Autoclaved conditioned medium from R. indica lost its promoting effect, while that from Sonia lost its inhibiting effect after autoclaving. The possible interaction between the rootstock and scion tissues is discussed.     

Zeatin and TDZ-induced Shoot Proliferation and Use of Bioreactor in Clonal Propagation of Medicinal Herb, Roseroot (Rhodiola rosea L)

A procedure for in vitro propagation of roseroots (Rhodiola rosea L), a medicinal plant, was developed using a RITA bioreactor system containing liquid medium, combined with a gelled medium. Wild roseroot clones: ‘RCi’, ‘RC2’ and ‘RC3’ were established on a basal medium (BM) from in vitro-germinated seedlings on half-strength Murashige and Skoog (MS) salts. TDZ at 2–4 μM supported shoot proliferation but inhibited shoot elongation of ‘RCi’ shoots on gelled medium. Clones differed significantly with respect to multiplication rate with ‘RCi’ producing the most shoots per explant on gelled BM with 2 μM zeatin. In a bioreactor system, TDZ supported rapid shoot proliferation at lower concentration (0.5 μM) but induced hyperhydricity at more than 0.5 μM. Bioreactor-multiplied hyperhydric shoots of all clones when transferred to gelled medium containing 1–2 μM zeatin produced normal shoots within 4 wk of culture. Shoots were rooted in vitro on BM void of growth regulators. Almost all (9U to 95%) in vitro plantlets survived when transferred to potting medium.     

Ultrastructural changes in major organelles during spermatial differentiation inBangia (Rhodophyta)

Summary The major organelles within the cells of maleBangia atropurpurea (Roth) C. Ag. filaments undergo a series of ultrastructural transformations during the production of spermatia. Initially, thylakoids within the large axial chloroplast develop a reticulate pattern commencing at the central pyrenoid region. Subsequent changes involve loss of lobes and diminution of volume through division; chloroplasts in final stages contain a few dilated, distorted thylakoids and many plastoglobuli. During differentiation the large nucleolus disappears from the nucleus and four masses of chromatin aggregate near the nuclear envelope. Furrows originating from the nuclear envelope form double membranes around each of the chromatin masses and most of the nucleoplasm is eliminated. Several types of fibrillar vesicles are formed during the process and large floridean starch reserves are utilized. Multilamellar bodies and microbody-like structures occur within the cells during certain phases of spermatiogenesis.     

Function of the photosynthetic apparatus of oilseed winter rape under elicitation by Phoma lingam phytotoxins in relation to carotenoid and phenolic levels

Stem canker (blackleg) caused by fungus Leptosphaeria maculans/L. biglobosa is one of the most damaging diseases of oilseed winter rape crops. Some winter oilseed rape varieties (Brassica napus L. var. oleifera ‘Bojan’, ‘Lisek’, ‘Liclassic’) that differ in blackleg resistance have been chosen for the experiment. In all tested cultivars during growth on a medium with a fungal elicitor, a distinct reduction in the length of the stems, the roots and the entire length of the seedlings was observed. However, only in the case of the ‘Liclassic’ cultivar, fresh and dry weight were reversibly affected during elicitation. The cultivar ‘Liclassic’, recognized as blackleg mildly resistant, was characterized by the most efficient photosynthetic apparatus under toxin elicitation. The efficient adaptation of photosynthetic apparatus in this cultivar was accompanied by an increase in the content of phenolics, chlorophyll and carotenoids. Only for ‘Liclassic’, did most of the measured parameters of chlorophyll fluorescence (F _v′/F _m′, Φ_PSII, q _P and q _N) exhibit a statistically significant correlation with regard to the level of carotenoids. Therefore, in‘Liclassic’, the observed increase in carotenoid content seems to be a significant biochemical factor which can raise the efficiency of the photosynthetic apparatus under elicitation by Phoma lingam toxins.     

A study of sexual receptivity in Blabera craniifer Burm. (Blattaria)

In females of the Blaberidae sexual receptivity is inhibited during the preoviposition period and during gestation. Similarly affected are oöcyte development and corpora allata activity during pregnancy. Roth (1964b) believes causation to be due to the mechanical action of the oötheca, but Engelmann (1964) believes it is due to the intervention of a humoral agent.In normal females of Blabera craniifer sexual receptivity is linked to the presence or absence of the oötheca in the brood sac. If the oötheca is not placed in the brood sac receptivity appears sooner than in a pregnant female.If certain afferent pathways are suppressed (by severing the nerve cord), or upset (by anaesthesia or in surgical controls) during pregnancy, only a partial receptivity is shown: straddling of the female on the male abdomen, ‘licking’ of tergal secretions, but no insertion by the male occurs. Such reactions are repeated over several days, giving an alternation of partial receptivity/non-receptivity which differs from that shown in normal animals. At times desynchronization between the receptivity and laying cycles is observed. This leads to the same conclusion as Roth and Barth (1964) that receptivity is not directly controlled by the corpora allata. We believe that the control ‘centre’ of receptivity has an autonomous rhythm, which is normally hidden but which appears when the afferent pathways are lacking or upset. The control mechanism of mating behaviour is probably a neuro-endocrine mechanism.     

Local adaptation in populations of a Brachionus group plicatilis cryptic species inhabiting three deep crater lakes in Central Mexico

1. Salinity is a strong selective force for many aquatic organisms, affecting both ecological and evolutionary processes. Most of our knowledge on the effects of salinity on rotifers in the Brachionus plicatilis species complex is based mainly on populations from waterbodies that experience broad environmental changes both seasonally and annually. We tested the hypothesis that, despite the supposedly high potential for gene flow among rotifers inhabiting neighbouring environments, constant salinity has promoted local adaptation, genetic population divergence and even cryptic speciation in B. plicatilis complex populations from three deep maar lakes of distinct salinities [1.1, 6.5 and 9.0 g L^?1 total dissolved solids (TDS)] in Central Mexico. 2. To look for local adaptation, we performed common garden experiments to test the effect of different salinities on population density and intrinsic growth rate (r). Then, we evaluated the genetic divergence by sequencing the cytochrome c oxidase subunit I (COI) gene and performed reproductive trials to assess the potential gene flow among the three populations and with other closely related B. plicatilis complex species. 3. We confirmed that the rotifer populations have phenotypic plasticity in tolerance of salinity, but only rotifers from the least saline lake are adapted to low salinity. Among the populations, sequence divergence at COI was very low (just a single haplotype was found), suggesting a persistent founder effect from a relatively recent single colonisation event and a subsequent dispersal from one lake to the others, and a very restricted immigration rate. In the phylogenetic analysis, rotifers from this area of Mexico clustered in the same clade with the middle‐sized species Brachionus ibericus and B. sp. ‘Almenara’. Mexican rotifers showed successful recognition, copulation and formation of hybrids among them, but interpopulation breeding with the Spanish B. ibericus and B. sp. ‘Almenara’ was unsuccessful. 4. We conclude that the B. plicatilis complex populations from these three lakes belong to a new biological species not yet described (presently named B. sp. ‘Mexico’). To our knowledge, this is the first report of local adaptation of a natural B. plicatilis complex population living in freshwater conditions (1.1 g L^?1 TDS).     

Ethanol-induced changes in the membrane lipid composition of Clostridium thermocellum

When ethanol is added to the growth medium of Clostridium thermocellum ATCC 27405 and C9, a different membrane composition is observed after the period of growth arrest. Changes in fatty acid composition and some unsaturated, branched hydrocarbons have been monitored by GLC-MS. There is a marked increase in normal and anteiso-branched fatty acids at the expense of isobranched fatty acids and an increase in short and unsaturated fatty acids. Thus, an adaptive response to growth in the presence of ethanol induces a membrane containing fatty acids with lower melting points and produces a more ‘fluid’ membrane. The suggestion is made that these membrane changes may be maladaptive to the performance of C. thermocellum.     

A naturally-occurring structural analogue of the phytotoxin coronatine

Chlorosis-inducing compounds in liquid cultures of the phytopathogenic bacterium Pseudomonas syringae pv. atropurpurea have been investigated. In addition to coronatine as previously reported, a new compound was discovered. This gave a mass spectral fragmentation pattern which indicated that it was, like coronatine, an amide of coronafacic acid. Acid-hydrolysis of the new toxin liberated the amino acid valine. This observation, together with mass spectral and NMR data, established the structure of the new toxin as N-coronafacoylvaline. Some implications to biosynthesis are discussed. Along with the two chlorosis-inducing compounds, the biologically inactive coronafacic acid was also isolated from the growth medium.     

Impacts of Carpobrotus edulis (L.) N.E.Br. on the Germination,Establishment and Survival of Native Plants: A Clue for Assessing Its Competitive Strength

Does Carpobrotus edulis have an impact on native plants? How do C. edulis’ soil residual effects affect the maintenance of native populations? What is the extent of interspecific competition in its invasion process? In order to answer those questions, we established pure and mixed cultures of native species and C. edulis on soil collected from invaded and native areas of Mediterranean coastal dunes in the Iberian Peninsula. We examined the impact of the invader on the germination, growth and survival of seeds and adult plants of two native plant species (Malcolmia littorea (L.) R.Br, and Scabiosa atropurpurea L.) growing with ramets or seeds of C. edulis. Residual effects of C. edulis on soils affected the germination process and early growth of native plants in different ways, depending on plant species and density. Interspecific competition significantly reduced the germination and early growth of native plants but this result was soil, density, timing and plant species dependent. Also, at any density of adult individuals of C. edulis, established native adult plants were not competitive. Moreover, ramets of C. edulis had a lethal effect on native plants, which died in a short period of time. Even the presence of C. edulis seedlings prevents the recruitment of native species. In conclusion, C. edulis have strong negative impacts on the germination, growth and survival of the native species M. littorea and S. atropurpurea. These impacts were highly depended on the development stages of native and invasive plants. Our findings are crucial for new strategies of biodiversity conservation in coastal habitats.     

Physiological adaptation to a newly observed low light intensity state in intact leaves,resulting in extreme imbalance in excitation energy distribution between the two photosystems

In intact leaves, a new physiological state is obtained reversibly at low light intensity (typically 1 W / m²), in which oxygen evolution yield, monitored by the photoacoustic method, approaches zero. In this ‘low-light’ state, irradiation with far-red (λ > 700 nm) background light immediately restores the normal oxygen yield, resulting in an unusually high Emerson enhancement ratio. Quantitative analysis of the enhancement ratio and the saturation curve of enhancement by far-red light shows that in the new state, short wavelength excitation does not reach PS I reaction centers, resulting in an extreme imbalance between the two photosystems. We suggest that adaptation to the low-light state occurs through loss of excitonic interaction between antennae of PS I and their reaction-centers. It appears also that the ‘far-red’ absorbing pigments do not participate in the disconnection and remain closely attached to the reaction centers of PS I. Their number is estimated to be less than 30 per reaction center. The disconnection of the antennae from the reaction center appears to be reversed by readaptation to ‘normal’ light levels, as well as by a brief preillumination with broad band (400–600 nm) light, acting as a trigger. In the last case, the transition to high oxygen yield state is transient. The quantum requirement of this recovery process is very small (approx. 10 hv / reaction center). The adaptation times after switching from higher to lower intensities and vice versa are in the range of minutes. The fluorescence yield remains virtually constant during adaptation to the low-light state in contrast to expectations, suggesting the possibility of cyclic electron flow around PS II in this state. In a chlorophyll-b-less barley mutant, which lacks the light-harvesting $\text{chlorophyll}\text{-}\text{a}\text{b}$ protein (LHC) (and possibly the newly discovered light-harvesting $\text{chlorophyll}\text{-}\text{a}\text{b}$ protein associated with PS I (LHC-I)), the ‘low-light’ state was absent. These results are consistent with the hypothesis that these antennae complexes participate directly in the adaptation to low light intensities.