On the conspecificity of marine and freshwater Bangia in Britain

The salinity responses of marine and freshwater Bangia have been studied in laboratory culture. Although both isolates possessed salinity tolerances which were dependent upon the salinity regimes of their original habitats, neither was restricted in its salinity tolerances to that salinity range alone. The marine isolate was able to proliferate after a single step transfer into a freshwater-based medium. Certain cells within the thallus appeared to be resistant to the sudden decrease in salinity and these developed into dwarf plantlets, following a period of dormancy. An hypothesis is proposed that Bangia occurring in freshwater is a well-adapted ecotype of the marine form, thus supporting the conspecific theory.     

Stabilization and modulation of the phycobilisome by calcium in the calciphilic freshwater red alga Bangia atropurpurea

The bangiophycean filamentous red alga Bangia atropurpurea is distributed in freshwater habitats such as littoral and splash zones of lakes or rapid currents distant from the sea. In these habitats, the distribution and growth of this alga appear to be related to hard water rich in calcium ions. To characterize the eco-physiological properties of this calciphilic red alga, we examined the effects of long-term and short-term Ca(2+) depletion on photosynthetic growth of the thallus and on the phycobilisome. Long-term culture experiments suggested that higher Ca(2+) concentrations (>50mgL(-1)) were required to sustain thallus growth and pigmentation of cells. In short-term Ca(2+)-depletion treatments, fluorescence derived from phycoerythrin (PE) fluctuated, although the absorption spectra of the thalli did not change. After 30 min of Ca(2+) depletion, the fluorescence lifetime of PE became markedly longer, indicating that the energy transfer from PE to phycocyanin (PC) was suppressed. The fluorescence lifetime of PE returned to its original value within a short time after 4h of Ca(2+) depletion, however, energy transfer from PE to PC was still suppressed. This suggested that the excitation energy absorbed by PE was quenched during prolonged Ca(2+) depletion. The efficient energy transfer from PC and allophycocyanin were unchanged during these treatments.     

Cell Wall Regeneration in Bangia atropurpurea (Rhodophyta) Protoplasts Observed Using a Mannan-Specific Carbohydrate-Binding Module

The cell wall of the red alga Bangia atropurpurea is composed of three unique polysaccharides (β-1,4-mannan, β-1,3-xylan, and porphyran), similar to that in Porphyra. In this study, we visualized β-mannan in the regenerating cell walls of B. atropurpurea protoplasts by using a fusion protein of a carbohydrate-binding module (CBM) and green fluorescent protein (GFP). A mannan-binding family 27 CBM (CBM27) of β-1,4-mannanase (Man5C) from Vibrio sp. strain MA-138 was fused to GFP, and the resultant fusion protein (GFP–CBM27) was expressed in Escherichia coli. Native affinity gel electrophoresis revealed that GFP–CBM27 maintained its binding ability to soluble β-mannans, while normal GFP could not bind to β-mannans. Protoplasts were isolated from the fronds of B. atropurpurea by using three kinds of bacterial enzymes. The GFP–CBM27 was mixed with protoplasts from different growth stages, and the process of cell wall regeneration was observed by fluorescence microscopy. Some protoplasts began to excrete β-mannan at certain areas of their cell surface after 12 h of culture. As the protoplast culture progressed, β-mannans were spread on their entire cell surfaces. The percentages of protoplasts bound to GFP–CBM27 were 3%, 12%, 17%, 29%, and 25% after 12, 24, 36, 48, and 60 h of culture, respectively. Although GFP–CBM27 bound to cells at the initial growth stages, its binding to the mature fronds was not confirmed definitely. This is the first report on the visualization of β-mannan in regenerating algal cell walls by using a fluorescence-labeled CBM.     

The Galactan Sulphates of the Conchocelis Phases of Porphyra leucostricta and Bangia atropurpurea (Rhodophyta)

Galactan sulphates have been extracted from mechanically isolatedcell walls of laboratory cultured conchocelis phases of Porphyraleucostricta and Bangia atropurpurea and their structure establishedby chemical methods and ¹³C-n.m.r. spectroscopy. The polysaccharidesrepresent an extreme structure for porphyran-type polymers inthat they consist almost entirely of 3-linked ß-D-galactosylresidues alternating with 4-linked -L-galactose-6-sulphate residues,the molar ratio of D to L units being approximately 1: 1. ¹³C-n.m.r.and gas-liquid and paper chromatography gave no indication of6-O-methyl-D-galactose in these polymers. Conchocelis galactansare chemically distinct from porphyrans of generic phases ofPorphyra and Bangia. Key words: Rhodophyta, Galactans, Cell walls     

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.     

The Taxonomy of Sphacelaria cirrosa (Roth.) Ag., Sphacelaria fusca (Huds.) Ag., and Sphacelaria furcigera (Kutz.) Sauv: A Simple Statistical Approach

An attempt has been made to apply some simple statistical techniquesto the taxonomy of a problematical group of species within thegenus Sphacelaria Lyngb. Measurements were carried out on materialcollected from the field, material made available from Herbariumcollections and on material grown under experimental conditionsThe main characteristics considered are cell and filament dimensions,although certain reproductive structures have also been measured. It has been found that the number of longitudinal divisionsin each segment of the main axes and the primary branches hasa profound effect on the over-all appearance of the fronds ofthe three species investigated. Segment length breadth ratioand frond stiffness have been shown to be dependent on the numberof longitudinal walls. This characteristic has enabled one ofthe species, S. cirrosa (Roth) Ag., to be readily distinguishedfrom the other two. Another factor shown to be important is the determinate patternof growth displayed by S. cirrosa as opposed to the indeterminatepattern displayed by S. fusca (Huds ) Ag. and S. furcigera (Kutz.)Sauv. The pattern of growth affects the number of longitudinalwalls, filament width, and the relative lengths of the primarybranches. The angle at which branches emanate from the main axes has beenshown to be a useful characteristic in this group of species. The variability in the number of arms produced by each propagulepresents an interesting problem which has only been described,experimental work suggesting no explanation for this phenomenon.The degree of variability is clearly different in each speciesand is useful taxonomically if a large enough sample is availablefor examination.     

Living in the intertidal zone - seasonal effects on heterosides and sun-screen compounds in the red alga Bangia atropurpurea (Bangiales)

The seasonal patterns of daylength and ultraviolet radiation (UVB and UVA) at Williamstown, Victoria, Australia were measured (October 1995-May 1996) and are considered in relation to levels of heterosides (soluble sugar compounds: D-isofloridoside, floridoside and L-isofloridoside) and sun-screen compounds (mycosporine-like amino acids: MAAs) in the intertidal red alga Bangia atropurpurea. UVB peaked in December-January at 2.2-2.4 W m(-2) and UVA also peaked at 70 W m(-2) in the same period. Total heteroside concentrations were highest (1230-1900 mmol kg(-1) dry weight) during November-December with floridoside and D-isofloridoside being 90% of the total. In late February through mid-April total heteroside contents were lower (315-905 mmol kg(-1) dry weight) with L-floridoside being as much as 34% of the total indicating a seasonal effect. Total MAAs varied from 3.4 to 7.1 mg g(-1) dry weight (mean 4.9 mg g(-1) dry weight) with both highest and lowest levels occurring in February. Porphyra-334 constituted 83 to 97% of this total with asterina-330, palythine and palythinol being 3-17%. Although maximum MAA concentrations did not show any significant parallel with the peak UV values, the quantitative data point to Bangia cells over the course of the seasons always loaded up with these photoprotective compounds.     

The ionic relations of Porphyra purpurea(Roth) C.Ag. (Rhodophyta, Bangiales)

Abstract Radioisotope equilibration techniques have been used to determine the intracellular concentration of K⁺, Na⁺ and Cl_?, together with the unidirectional ion fluxes across the plasmalemma of Porphyra purpurea. Influx and efflux of ⁴²K⁺, ²⁴Na⁺ and ³⁶C1^? are biphasic, the rapid, initial uptake and loss of tracer from individual thalli being attributable to desorption from extracellular regions. Cellular fluxes are slower and monophasic, cells discriminating in favour of K⁺ and Cl^? and against Na⁺. A comparison between the equilibrium potential of individual ion species and the measured membrane potential demonstrates that there is an active component of K⁺ and Cl^? influx and Na⁺ efflux. ‘Active’ uptake and ‘passive’ loss of K⁺ and Cl^? are reduced when plants are kept in darkness, suggesting that a fraction of the transport of K⁺ and Cl^? may be due to ‘exchange diffusion’ (K⁺/K⁺ and Cl^?/Cl^?antiport).     

Characterization of a birch (Betula pendula Roth.) embryogenic gene,BP8

We have isolated the birch homologue (BP8) for the carrot embryogenic gene DC8 by heterologous hybridization. The birch BP8 gene encodes a putative protein of 53 kDa, showing 52% sequence identity with the DC8 gene at the amino acid level. The putative BP8 protein contains 20 repeats of 11 amino acids and thus belongs to the group of LEA proteins isolated from such plants as carrot, cotton and wheat. Northern hybridization of mRNA isolated from birch cells representing different stages of somatic embryogenesis and non-embryogenetic material with a PB8 probe gave no signals, suggesting a low expression level of the BP8 gene.     

Somatic embryogenesis in cell cultures of birch (Betula pendula Roth.)

Somatic embryogenesis was induced in cell cultures of birch (Betula pendula Roth.) derived from juvenile tissue of seed embryos and from mature leaf tissue. Embryos were formed in liquid and on solidified medium containing 2,4-dichlorophenoxyacetic acid (2,4-D) and 6-furfurylaminopurine (kinetin). Sometimes somatic embryos formed only after transfer to medium devoid of growth regulators. The embryos germinated on hormone-free medium and were potted in soil and grown in the greenhouse.Finnish Forest Research InstituteUniversity of Helsinki, School of Pharmacy;     

The Effects of Salinity upon Cellular Volume of the Marine Red Alga Porphyra purpurea (Roth) C.Ag.

Changes in cell volume of the marine red alga Porphyra purpureahave been investigated using photomicroscopic and radioisotopictechniques. There is an inverse relationship between cell volumeand external salt content. The alga responds to changes in thewater potential of its bathing medium by rapid swelling in hyposalinemedia and shrinkage in hypersaline conditions. Cells P. purpureabehave as osmometers in concentrated sea-waters, obeying theBoyle-Van't Hoff law. A non-osmotic volume, 20–25% ofthe total cell volume in sea-water, can be predicted from thelinear plot of volume versus reciprocal pressure in concentratedsea-water media. In dilute sea-waters the presence of non-rigidcell walls serves to limit any increases in cell volume. Theprimary response to dilution stress is thus an increase in turgor.Cell volume is not returned to its original value followingprolonged immersion in either hyposaline or hypersaline media,showing that the alga does not ‘osmoregulate’ sensustricto.     

Grimmia agassizii (Sull. & Lesq.) Jaeg. in Britain

Abstract

The marked differences between Plagiochila spinulosa (Dicks.) Dum. and P. killarniensis Pears. pointed out by Paton (1977) are confirmed and added to by further ones. As a result the two species are placed in different sections Spinulosae and Zonatae, respectively. For each of the two species the full synonymy including new synonyms and new lectotypifications and a comprehensive list of studied specimens and a distribution map are presented. In appendix, P. porelloides (Torrey ex Nees) Lindenb. is recorded from Madeira, a species new to Macaronesia.     

Pohlia lutescens (Limpr.) Lindb. F. in Britain and Ireland

Abstract

Background, reference, and instructional information is provided to enable the best possible photographic recording of mosses and similar plants, using equipment that is generally available from High Street outlets; specialist techniques rely more on improvisation than on specialist equipment. About half of the paper consists of straight forward instructions and hints for photography ranging from habitat shots to extreme macro, and dealing with special categories including luminous mosses, time sequence, and capsules. A step-by-step basic example of procedure is provided for a simple macro setup for field work. The paper presumes a basic photographic understanding, but elaborates on those aspects that are particularly relevant to moss photography. Sections deal with determining image magnification, and recording procedures. A close-up flash calculator dial (original) is provided, with instructions to help with flash exposure for all natural history work. Also an appendix of relevant formulas (some original) is provided, as are graphs (both original) for depth of field and resolution at all apertures and magnifications up to × 10, for all subjects.     

Acrochaetium botryocarpum (Harv.) J. Ag. (Rhodophyta) in Southern Australia

The morphology, ecology, cytology and systematics of Acrochaetium botryocarpum (Harv.) J. Ag. have been studied. This species occurs throughout the year in southern Australia and grows on a variety of hosts. The variable appearance of the prostrate system results from the effect of the substratum upon its morphology. Plants reach a height of 6 mm; cells of the erect filaments contain a single chromoplast with a variable number of pyrenoids. Tetrasporangial plants occur mainly in winter and sexual plants occur mainly in spring and early summer; the two generations are isomorphic. Stages of fertilisation have been observed and photographed. Acrochaetium polyrhizum (Harv.) J. Ag. is referred to the synonomy of A. botryocarpum, and A. codicolum Brg., A. grande (Levr.) De Toni fil. and A. rhizoideum (Drew) Sm. are regarded as probable synonyms. This study of A. botryocarpum indicates that host specificity, substrate relations, form of spermatangia and immediate post-fertilisation activity may not be as reliable as formerly thought for making taxonomic distinctions within the Acrochaetium-Rhodochorton complex.     

The status of the otter (L. lutra L.) in Britain in 1977

Two surveys based on otter hunt records showed a 40% fall in the otter population 1957–1967, arrested and in places reversed by 1971 save in the central Midlands. The possible causes of that decline and of its apparent continuation in the Midlands are discussed. While accepting those two surveys most conservationists have since then refused to accept or consider any evidence from otter hunts: the writer does not. Reports of the presence of otters by naturalists are shown plotted on a map and suggest that they are present in sufficient numbers and at a sufficient density over the whole of Great Britain, save the central Midlands, to ensure a recovery to the pre-1960 density. Positive evidence found by hunts in a number of places in which naturalists had found none suggest that negative evidence should be accepted with caution.     

The occurrence of Homalothecium nitens (Hedw.) Robins. in Ireland

Abstract

Eight new localities for Homalothecium nitens (Hedw.) Robins are recorded from north Co. Mayo, Ireland. The first observations of H. nitens in fruit in Ireland are reported.