Two new species of Haptoglossa from north-east England

Two new species of Haptoglossa , one zoosporic, H. northumbrica , and one aplanosporic, H. polymorphs, , were isolated from samples of manure and horse dung in north-east England. The zoosporic H. northumbrica is morphologically similar to H. dickii but differs in having slightly smaller infection gun cells with a unique internal arrangement of cones in the apical missile chamber. The thallus of the aplanosporic H. polymorpha is similar to H. heteromorpha but produces three different types of aplanospore. The smaller cysts either develop into broad, arcuate gun cells or form curved adhesive cells that have a rounded base. These curved adhesive cells have very different internal ultrastructural organization. The large cysts develop into infection cells that are morphologically similar to the curved adhesive cells, but their internal structure has not yet been observed.     

CALCIFICATION IN THE GREEN ALGA HALIMEDA. I. AN ULTRASTRUCTURE STUDY OF THALLUS DEVELOPMENT1

The ultrastructure of 4 species of the calcareous, siphonaceous alga Halimeda (H. cylindracea Decaisne, H. discoidea Decaisne, H. macroloba Decaisne and H. tuna (Ellis & Solander) Lamour) has been studied, and the observed changes during growth and development are related to changes in the degree of calcification. A distinct gradient in the types and quantities of cell organelles exists in a growing apical filament. As these filaments grow, branch, and eventually develop into a mature segment, changes in the organization of organelles such as mitochondria and chloroplasts are observed. Calcification begins when the chloroplasts reach structural maturity and when the peripheral utricles adhere (fuse). This adhesion of the peripheral utricles isolates the intercellular space (ICS) in which calcification occurs from the external seawater. Calcification begins in the outermost (pilose) cell wall layer of the walls facing into the ICS. The cell walls at the thallus exterior undergo extensive changes after utricular fusion; the pilose layer is lost, the cuticles of adjacent utricles fuse forming a ridge at their junction, and multiple cuticles are formed. The aragonite (CaCO₃) crystals which are initially precipitated within the pilose wall layer, rapidly increase in size and number, eventually filling much of the ICS. Only the initial nucleation of aragonite is associated with the pilose wall layer, the later precipitation of aragonite is totally independent of the pilose layer. In older segments secondary deposition of CaCO₃ also occurs around existing aragonite needles.     

Arthopyrenia endobrya,spec. nov., eine hepaticole Flechte mit intrazellulärem Thallus aus Brasilien

Arthopyrenia endobrya from Southern Brazil is illustrated and described as a new species of lichens. The thallus is composed of filamentous green algae loosely surrounded by fungal hyphae. Both symbionts grow endophytically within the leaf cells of two species ofLejeuneaceae (Hepaticae). The algae and hyphae penetrate the cell walls of the host by means of fine perforations. The ascocarps develop between the leaves and perforate them with their apical region. The classification as a member of the genusArthopyrenia is preliminary.

     

THALLUS MORPHOLOGY AND SPORE FORMATION IN CULTURED ERYTHROCLADIA IRREGULARIS ROSENVINGE (RHODOPHYTA,BANGIOPHYCIDAE)1

The discoid thallus of Erythrocladia irregularis is the result of a pattern of cellular divisions expressed by mono-and endospores; the latter are described for the first time in Erythrocladia. In nutrient enriched growth conditions the discoid thallus becomes a shapeless aggregate of unicells with a wrinkled wall surface, whose plane of division is unpredictable. The cells are able to produce monosporangia with a curved wall or they form eight-celled endosporangia. Chloroplasts have an internal pyrenoid, as is characteristic of the Erythropeltidaceae. The observation that E. irregularis can form either a colonial cluster of unicells or a discoid thallus would lead to the assignment of the genus to the Porphyridiales; however, since this order is reserved to organisms in which only the unicellular organization can be expressed, it is suggested to maintain Erythrocladia in the Erythropeltidales.     

Intra‐thallus differentiation of fatty acid and pigment profiles in some temperate Fucales and Laminariales

Intra‐thallus variation in fatty acid and pigment contents and profiles was investigated in five species of Laminariales (Alaria esculenta, Laminaria digitata, Laminaria hyperborea, Saccharina latissima, and Saccorhiza polyschides), and three Fucales (Ascophyllum nodosum, Fucus serratus, and Himanthalia elongata). Significant variation occurred across all species and compounds examined. Total fatty acids were generally higher in the fronds, with highest levels and largest variability observed in A. nodosum (1.5% of dry weight (DW) in the base, 6.3% of DW in frond tips). Percentages of the omega‐3 fatty acids 18:4 n‐3 and 20:5 n‐3 were generally higher in more distal parts, while 20:4 n‐6 exhibited a contrasting pattern, with higher levels in basal structures and holdfasts. Trends for pigments were similar to those for fatty acids in Laminariales. In the Fucales, highest levels were detected in the mid‐fronds, with lower concentrations in meristematic areas. Highest levels and greatest variability in pigments (e.g., chl a) was observed in F. serratus (1.07 mg · g^?1 DW in the base, 3.04 mg · g^?1 DW in the mid frond). Intra‐thallus variability was attributed to physiological functions of the respective thallus sections, e.g., photosynthetic activity, meristematic tissue, and to variations in physical attributes of the structures investigated. Regarding potential commercial nutritional applications, fronds appeared to represent most suitable source materials, due to higher levels of pigments, polyunsaturated fatty acids, and more preferable omega‐3/omega‐6 ratios.     

Ulva flexuosa (Ulvaceae,Chlorophyta) inhabiting inland aquatic ecosystems: molecular,morphological and ecological discrimination of subspecies

Species of Ulva (Ulvaceae, Chlorophyta) are relatively common macroalgae in most coastal areas. In this paper, we examine Ulva in inland aquatic ecosystems to determine relationships between the chemical parameters of the water and the Ulva taxa present. Two groups of samples of freshwater Ulva were selected from: (i) habitats with high salinity levels, and (ii) habitats with fresh or slightly saline waters. We showed that these two groups of Ulva, which occupy distinct habitats, represent two separate taxa. The first group represents Ulva flexuosa subsp. pilifera (Kützing) M.J. Wynne, which is very common and regularly encountered in fresh waters, but is equally well represented in slightly saline waters. The second is U. flexuosa subsp. paradoxa (C. Agardh) M.J. Wynne, which is less common, preferring mainly salt-wedge saline waters. We did not find both Ulva flexuosa subspecies together at any of the research sites.

There were significant morphological differences between the Ulva flexuosa subspecies. Ulva flexuosa subsp. pilifera had longer and wider thalli and wider cells than those of subsp. paradoxa. Ulva flexuosa subsp. paradoxa cells were longer and of greater circumference than those of subsp. pilifera. Analyses of the rRNA ITS region and partial rbcL gene sequences demonstrated minor sequence variation within the two subspecies. The results of this study provide detailed information on the characteristics of limnic Ulva habitats and indicate the niches where such populations are likely to occur.     

Thymol derivatives from Eupatorium glechonophyllum

The known 10-acetoxy-8,9-epoxythymolisobutyrate and the new 8,9-dihydroxy-10-acetoxythymolisobutyrate and 8,9,10-trihydroxythymol have been isolated from the thallus of Eupatorium glechonophyllum. The acetonide of the last compound was also obtained. The possibility that the new compounds are artefacts is discussed.     

紫萍叶状体衰老过程中的内肽酶谱变化和外源L-丝氨酸对内肽酶谱的影响

采用双向凝胶电泳技术分析紫萍叶状体衰老期间内肽酶同工酶的变化以及外源L-丝氨酸对内肽酶影响的结果表明,在衰老的紫萍叶状体中检测到9种内肽酶同工酶,丝氨酸内肽酶EP3可能在叶状体衰老的早期起作用,而半胱氨酸内肽酶EP9在第6天出现,是衰老后期活性最强的内肽酶。培养液中加入外源的L-丝氨酸后,叶状体蛋白质含量下降加剧,与衰老相关的内肽酶EP3、EP4和EP9的活性明显增强或提前出现。     

Trade‐off relationship between productivity and thallus toughness in Laminariales (Phaeophyceae)

Trade‐off relationships are considered key to understanding the mechanisms supporting the coexistence of multiple species within kelp beds. Thus, information on trade‐offs is expected to contribute to conservation of kelp bed diversity. To test the existence of a trade‐off between productivity and thallus toughness, thallus traits and relationships between the traits were examined for seven species of Laminariales including 24 populations. For each population, photosynthetic capacity per unit biomass (as A _mass) and nitrogen (i.e., photosynthetic nitrogen‐use efficiency, PNUE), nitrogen content (as N _mass), thallus mass per unit thallus area (as TMA) and force required to penetrate the thallus (as F _p, a common index of leaf toughness in land plants by punch test) were determined. A _mass increased with increasing N _mass. Blades with high N _mass showed high A _mass. These blades may invest a large proportion of nitrogen to the photosynthetic parts, and consequently exhibit high metabolic rates. Moreover, blades with high N _mass tended to be associated with low TMA, and N _mass decreased with increasing TMA. A significant negative correlation was observed between TMA and A _mass because of the linkage of high A _mass with high N _mass and high N _mass associated with low TMA, while a significant positive correlation was observed between TMA and F _p. The two correlations indicate the existence of a trade‐off between productivity and thallus toughness in Laminariales. PNUE showed a significant negative correlation with TMA, which also showed a significant positive correlation with F _p as the index of thallus toughness, and therefore a trade‐off relationship between productivity and thallus toughness.     

光强对浒苔充气叶状体内氧气浓度的影响

以烟台海域定生浒苔为研究对象,采用光暗转换法,研究了不同光强条件下浒苔充气叶状体内部氧气浓度的变化。结果表明,浒苔充气叶状体内部气体成分中含有氧气,其浓度在360μmol/m2.s光强下达到最高值且保持稳定,光暗转换法显示其最高稳态到最低稳态的过渡仅需约10 s,此外,最低稳态的氧浓度仍高于水体饱和溶氧浓度。