首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 0 毫秒
1.
Two new species are recognized in the rhodomelacean genus Tayloriella Kylin: T. divaricata sp. nov. and T. abyssalis sp. nov. These two taxa are distributed in the northeastern North Pacific, the former ranging from Amchitka Island in the Aleutians through southcentral Alaska to northern British Columbia, and the latter ranging also from Amchitka Island through southcentral Alaska and British Columbia into northern Washington. A characteristic of these two species shared with the type of Tayloriella is that the abaxial lateral always overtops the monopodially developed axes in every order of branching. The laterals have little congenital fusion with the parent axes. A common feature in these two species is that the laterals are terminated in a relatively long monosiphonous portion (usually 6 or 7 cells). The relationship of Tayloriella to Pterosiphonia and Pterosiphoniella is discussed.  相似文献   

2.
Among five species of the genus Plocamium Lamouroux distributed around Japan, P. cartilagineum (Linnaeus) Dixon, P. recurvatum Okamura and P. telfairiae (Hooker and Harvey) Harvey are often difficult to distinguish morphologically from each other. Our previous study demonstrated that P. recurvatum and P. telfairiae were divided into two groups, A and C, based on RUBISCO spacer sequence and that the specimens belonging to group C had acidic cell saps. In this study, we inferred evolutionary relationships of these Plocamium species from internal transcribed spacer sequence of the ribosomal RNA genes and obtained a similar topology to the RUBISCO spacer tree. Color of the dried specimens in the acidic group C was darker red than that in the non‐acidic group A, although there was no difference in color in living thalli. The Br? concentration in the cell sap of the acidic group C was 20 times higher than that of the non‐acidic group. We could not find any morphological differences to distinguish clearly between groups A and C despite exhaustive investigation of field‐collected and cultured thalli in both P. recurvatum and P. telfairiae. These results suggest that the color of dried specimens and the composition of intracellular inorganic ions are significant criteria for interpreting phylogenetic relationships in Japanese Plocamium spp.  相似文献   

3.
Synarthrophyton gen. nov. is described based on southern Australian material of Melobesia patena Hooker fils & Harvey, which shows features intermediate between Mesophyllum Lemoine and Lithothamnium Philippi. It has the thin-walled rounded epithallial cells and coaxial hypothallium characteristic of Mesophyllum and the type of procarp and male structures common to Lithothamnium. Synarthrophyton is unique within the subfamily Melobesioideae (J. E. Areschoug) Yendo because it displays secondary pit connections. Details of the vegetative and reproductive morphology of S. patena (Hooker fils. & Harvey) comb. nov. are given and its taxonomic position in the Corallinaceae Lamouroux discussed.  相似文献   

4.
Three genera of macrophytic red algae ( Ochtodes , Plocamium , and Portieria ) contain novel halogenated monoterpenes. To develop an in vitro system for studying halogenated monoterpene production, a laboratory tissue culture was established for Ochtodes secundiramea (Montagne) Howe (Cryptonemiales, Rhizophyllidaceae). Specifically, callus cells were induced from thallus explants of O. secundiramea plants. Shoot primordia regenerated from callus cells and developed into plantlets that released tetraspores. A sporeling from one of these tetraspores was selected for further culture. Axenic plantlets were cultivated in ESS-enriched natural seawater. Thallus tissue was cut into small pieces before subculture. Each plantlet grew as a symmetrical array of highly branched shoot tissues emanating from a common center, ultimately assuming a spherical shape of 20 mm diameter 4 weeks after subculture. Specific growth rates of over 20% per day were attained in bubble-aerated flask culture at an optimal temperature of 26° C and photosynthetic saturation light intensity of 200 μmol photons·m 2·s 1. The cultured plantlets contained myrcene and seven halogenated monoterpenes, based on gas chromatography–mass spectroscopy analysis of dichloromethane extracts. Although bromomyrcene was the dominant acyclic halogenated monoterpene, the cyclic halogenated monoterpenes chondrocole C and ochtodene were also produced by the O. secundiramea plantlet cultures. Halogenated monoterpene production at light-saturated growth conditions increased with decreasing nitrogen availability below 1.0 mM medium nitrate concentration (N:P ratios of 1.6:1 to 32:1). The halogenated monoterpene yield was insensitive to medium nitrate concentrations above 1.0 mM (N:P ratios of 32:1 to 320:1), where the bromomyrcene yield was 1700 μg per gram of dry cell mass.  相似文献   

5.
The polysaccharide extracted from Kappaphycus striatum (Schmitz) Doty (sacol variety), a recently farmed eucheumoid seaweed, was characterized by Fourier transform infrared and NMR spectroscopy. The extract is composed mainly of 3‐linked β‐d ‐galactopyranosyl‐4‐sulfate residues alternating with 4‐linked 3,6‐anhydro‐α‐d ‐galactopyranosyl residues (κ‐carrageenan). Minor components include 3,6‐anhydrogalactopyranosyl‐2‐sulfate residues (ι‐carrageenan) and 6‐O‐methylgalactopyranosyl‐4‐sulfate residues (methylated carrageenan). The substitution pattern of carrageenan in the tribe Eucheumatoideae and the family Solieriaceae is revisited in terms of chemotaxonomic affiliation.  相似文献   

6.
Lithium chloride facilitates the softening of cell walls resulting in a simple, quick (2 h) method for DNA extraction from the red seaweed Porphyra perforata J. Agardh. A 5-min treatment of tissues in Lid at 55°C extracts DNA that is relatively free of the viscous polysaccharides and proteins that are usually coextracted in large amounts from cell walls and cytoplasm. This protocol does not require grinding of tissues, hydroxyapatite binding, cetyl trimethyl ammonium bromide treatments, enzymatic treatments, phenol extraction, or CsCl-gradient centrifugation. The resulting DNA is of sufficient quality to be used as a template for polymerase chain reaction amplification.  相似文献   

7.
Species separation in the genus Laurencia (Rhodomelaceae, Rhodophyta) is complicated by the high degree of morphological variation within the species. Chemical investigations on a worldwide basis of over 15 species indicate that 1 or more of the halogenated natural products synthesized by Laurencia are unique to each species. Our chemical investigations of Laurencia pacifica, as presently understood from the Gulf of California, indicate that more than 1 species had been included under this name. Thin layer chromatographic (TLC) comparisons of the halogenated components of 3 recognizable forms of “L. pacifica” were completed. The results revealed 3 distinct forms, with halogenated products unique to each form. In each form the observed chemical characters had been previously isolated and identified and could now be positively assigned to their algal source. Comparisons were also conducted with L. pacifica Kylin (1941) from the type locality of the species, La Jolla, California, and revealed that it contained another halogenated product different from those isolated from the Gulf species. We conclude that 3 species of Laurencia have been elucidated in the Gulf of California and these are separate from L. pacifica Kylin. Each species can be distinguished by its characteristic array of halogenated compounds. Comparative thin layer chromatography of the lipid components of morphologically similar Laurencia species should prove to be a useful new taxonomic aid.  相似文献   

8.
Physical environment and physiological characteristics of marine mammals potentially affect the duration and depth of diving. Härkönen (1987b) proposed a hypothesis that the harbor seal would gain maximum energy by foraging at intermediate depths. To investigate this hypothesis, we studied diving behavior of the Pacific harbor seal (Phoca vitulina ricbardii) during 1995 through 1997 in Monterey Bay, California. Dive depths (n = 13,063 dives) were recorded via time‐depth recorders. Approximately 80% of recorded dives were classified as square dives (type I), which typically were associated with foraging in pinnipeds. Approximately 11% of dives were V dives (type II; 1,402 dives), and the remainder (1,225 dives) were skewed dives (type III and IV). The deepest recorded dive was 481 m, while the greatest duration was 35.25 min. Body mass explained the variability of durations of long dives for females (95th percentile; D95♂=‐5.47 + 0.18 × (mass♀), r2= 0.91, 95% CI for slope = [0.08, 0.28], n= 5) and for males (D95♂=‐5.86 + 0.18 × (mass♀), r2= 0.83, 95% CI for slope = [0.12, 0.24], n= 11). The large proportion of variability in deep dives, however, was explained by body mass only for males (95th percentile; Z95♂=‐363.9 + 6.05 × (mass♀), r2= 0.83, 95% CI for slope = [3.93, 8.17], n= 11) and not for females (Z95,♂=?148.1 +3.11 × (mass♀), r2= 0.58, 95% CI for slope = [‐1.7, 7.9], n= 5, 95% CI for slope= [?1.7, 7.9]). Median depths of presumed foraging dives of harbor seals in the Monterey Bay area were between 5 and 100 m, which were within the range of the previously reported depths for other areas (< 100 m). Our findings generally supported Härkönen's hypothesis that harbor seals forage in the intermediate depth in their environment.  相似文献   

9.
Transmission electron microscopy of the iridescent algae Iridaea flaccida (S & G) Silva, Iridaea cordata (Turn.) Bory var. cordata and I. cordata var. splendens (S & G) Abbott reveals a multilaminated cuticle covering the thallus. Experimental results show the cuticle: a) can be isolated intact by mechanical scraping or NaOH treatment; b) is iridescent by itself and the denuded thallus is not; and, c) is isolated without any subtending polysaccharide layer, cell walls, or cells. This cuticle acts as a thin layer producing the constructive and destructive light interference which is seen as iridescence. It is formed of alternating electron opaque and translucent layers with a total thickness of 0.5–1.6 μm. Analysis of mechanically isolated cuticle shows that it is composed of protein (50%), carbohydrate (ca. 40%), inorganic salts (5%) and some fatty acids (less than 1.0%). The electron opaque layers may correspond to protein-rich regions and the electron translucent ones to regions rich in carbohydrates. The cuticle does not appear to affect photosynthesis or respiration, but rather, may protect the alga from physical factors such as desiccation and from predator injury. It is likely that the iridescence in other foliaceous red algae is caused by a similar structure.  相似文献   

10.
Five Ceramiaceae (Rhodophyta) are reported from the offshore waters of the southeastern, warm temperate coast of the United States. These include two new monotypic genera, Calliclavula trifurcate Schneider in the Griffithsieae and Nwynea grandispora Searles in the Sphondylothamnieae, and three new species, Callithamniella silvae Searles, Ptilothamnion occidentale Searles, and Lejolisia exposita Schneider et Searles.  相似文献   

11.
The field of molecular paleontology has recently made significant contributions to anthropology and biology. Hundreds of ancient DNA studies have been published, but none has targeted fossil coralline algae. Using regions of the SSU gene, we analyzed rDNA from fossil coralline algae of varying ages and states of preservation from Spain, Papua New Guinea (PNG), and the Great Barrier Reef (GBR). Specimens from PNG, GBR, and some localities from Spain did not contain endogenous ancient DNA. Reproducible sequence data were obtained from specimens ~550 years old from near Cadiz, Spain, and from rocky‐shore deposits in Carboneras, Almeria Province of Spain (~78,000 years before present [YBP]). Based on BLAST searches and a phylogenetic analysis of sequences, an undescribed coralline alga belonging to the Melobesioideae was discovered in the Carboneras material as well as the following coralline genera: Jania, Lithophyllum, Lithothamnion, Mesophyllum, and Phymatolithon. DNA from fleshy brown and red macroalgae was also discovered in the specimens from Carboneras. The coralline algae identified using molecular techniques were in agreement with those based on morphological methods. The identified taxa are common in the present‐day southeastern Spain littoral zone. Amino acid racemization, concentration ratios, and specific concentrations failed to show a correlation between biomolecular preservation and PCR amplification success. Results suggest that molecular investigations on fossil algae, although limited by technical difficulties, are feasible. Validity of our results was established using authentication criteria and a self‐critical approach to compliance.  相似文献   

12.
Chironomid larvae incorporate pieces of freshwater red algae into their cases from a wide geographic range in North America, extending from southern Canada to central Mexico. The Rhodophyta used in this process represent two orders (Acrochaetiales and Batrachospermales), five genera (Audouinella, Batrachospermum, Lemanea, Paralemanea, and Sirodotia), and 14 species from 21 locations. Three genera from the chironomid subfamily Orthocladiinae make these cases: Cardiocladius, Eukiefferiella, and Orthocladius. The Eukiefferiella claripennis group was the most frequently observed infrageneric taxon using red algae in its cases. The cases were tubular in shape with longitudinally oriented strips of algae held together by silken threads. Some of the cases constructed with Batrachospermum and Sirodotia also had several lateral branches of the alga radiating from the tube.  相似文献   

13.
Molecular phylogenetic studies on the evolution of the red algae indicate that this ancient division has many lineages that have recently undergone radiations. One such example is the cold–temperate family Palmariaceae. In this study, sequences from the ribosomal DNA internal transcribed spacer regions were compared among ten species in the Palmariaceae from both Atlantic and Pacific sites, Phylogenetic analyses of sequence data, in which Rhodophysema georgii Batters was used as outgroup and root, indicate a radiation into four clades, three of which contain species of “Palmaria” and the fourth species of Halosaccion. Palmaria palmata (L.) Kuntze, the type and only North Atlantic species in the genus, stands apart from all remaining species in the family and terminates the most basal branch in the rooted tree. The three more derived clades have radiated mainly in the North Pacific. Southern Ocean Palmaria and North Atlantic Devaleraea are hypothesized to have invaded from separate but closely related North Pacific ancestors. The ease with which sequences could be aligned combined with an unsaturated transition: transversion ratio and modest divergence involving predominantly point mutations suggests that the initial radiation is relatively recent (late Miocene–Pliocene) and that the Devaleraea–Palmaria clade is even more recent (late Pliocene–Pleistocene).  相似文献   

14.
本文纪录了淡水红藻串珠藻属Batrachospermum的二个新种。它们采自中国的亚热地区,按其形态特征,它们属于旋转组Section Contorta。采自湖北省的弯形中珠藻B.curvatum与扭曲串珠藻B.tortuosum Kumano相似,但按其轮节、顶毛和受精丝等的形态与后者相区别。采自江西省的弯转串珠藻B.torsivum与赫罗西串珠藻B.hirosei Ratnasabapathy et Kumano相似,但轮节、中轴细胞、节丝和节间丝、果胞枝和受精丝等的大小和形态与后者相区别。  相似文献   

15.
16.
Following fertilization, the carposporophyte of Nemalion helminthoides (Velley in With.) Batters differentiates into four distinct regions: the fusion cell, the sterile gonimoblast cells, the carposporangial mother cells and the carposporangia. The gonimoblast is formed by apically dividing, monopodial filaments of limited growth which may later become pseudodichotomous. Upon differentiation of a terminal carposporangium, a gonimoblast filament may continue to grow sympodially. A single carposporangial mother cell may produce carposporangia in several different directions as well as proliferate successive carposporangia within the sporangial walls that remain after carpospore liberation. As the carposporophyte matures, the gonimoblast initial, the stalk cell, the hypogynous and subhypogynous cells fuse. Except for the fusion cell, all cells of the carposporophyte show organelle polarity and contain a distally located, lobed chloroplast and proximal nucleus.  相似文献   

17.
The reproductive composition and genetic diversity of populations of the red seaweed Lithothrix aspergillum Gray (O. Corallinales) were studied at three southern California sites (Shaw's Cove and Treasure Island, Laguna Beach; Indian Rock, Santa Catalina Island) and at a fourth site (Bodega Bay) located in northern California. Sexually reproducing populations were confined to southern California. Diploid individuals were numerically dominant over haploid (gametophytic) individuals at all sites. Intertidal and subtidal subpopulations from Shaw's Cove differed in their reproductive profiles. Most intertidal specimens found on emersed surfaces were densely branched, turf-forming, and bore tetrasporangial (68.6%), carposporangial (11.4%), or spermatangial (5.7%) conceptacles, reflecting a sexual life history; none produced asexual bispores. In contrast, 74.3% of the larger, loosely branched subtidal specimens bore bisporangial conceptacles indicative of asexual reproduction. Nearly 70% of the Indian Rock thalli showed no evidence of conceptacle formation. Only asexual, diploid bispore-producing thalli were obtained from the Bodega Bay site. Genetic diversity (mean number of alleles per locus, percent of polymorphic loci, and average expected heterozygosity) of diploid L. aspergillum populations varied with life-history characteristics and geographic location. A total of 30 alleles was inferred from zymograms of 16 loci examined by starch-gel electrophoresis; of these loci, 11 were polymorphic. The genetic diversity of sexual, diploid populations of L. aspergillum (alleles per locus [A/L] = 1.4-1.5; percent polymorphic loci [%P] = 37.5-50.0) was relatively high compared with other red seaweeds. Lowest diversity (A/L = 1.0; %P = 0.0) occurred in the exclusively asexual Bodega Bay population which consisted of genetic clones. All sexual L. aspergillum populations deviated significantly from Hardy-Wein-berg expectations due to lower than expected heterozygosity. Genetic differentiation (Wright's Fstatistic [FST]; Nei's Genetic Distance [D]) among sexually reproducing southern California populations was low (FST= 0.030) on a local scale (ca. 5 km), suggesting high levels of gene flow, but high genetic differention (FST= 0.390 and 0.406) occurred among southern California populations separated by ca. 70 km. Very high genetic differentiation (FST= 0.583–0.683) was obtained between northern and southern California populations separated by 700–760 km. Our genetic and reproductive data suggest that the L. aspergillum population from Bodega Bay is sustained by perennation, vegetative propagation, or asexual reproduction by bispores and may represent an isolated remnant or a population established by a founder event.  相似文献   

18.
Morphological investigations identified 11 Ceramium Roth species, of the 18 previously reported from Brazil. Phylogenetic analyses of sequences of the chloroplast‐encoded rbcL gene confirmed the presence of seven of these species. Three other species are reported from Brazil for the first time. Ceramium affine Setchell & Gardner and C. filicula Harvey ex Womersley were previously known only from the Pacific Ocean (Mexico and Australia, respectively). A new species, C. fujianum Barros‐Barreto et Maggs sp. nov., is described here. Its general habit is similar to that of C. strictum sensu Harvey from Europe but it has one less periaxial cell than C. strictum; its cortical filament arrangement is closest to C. deslongchampsii Chauvin ex Duby, also from Europe, but whorled tetrasporangia partially covered by cortical cells differ strikingly from the naked protruding tetrasporangia of C. deslongchampsii. Ceramium species in which each periaxial cell cuts off transversely only a single basipetal cell formed a robust clade. The genus Ceramium as represented in Brazil is not monophyletic with respect to Centroceras Kützing and Corallophila Weber‐van Bosse; Ceramium nitens, which has axial cells completely covered by rounded cortical cells formed by acropetal and basipetal filaments, did not group with any Ceramium clade but was weakly allied to a species of Corallophila. All three Brazilian Centroceras sequences were attributed to a single species, C. clavulatum.  相似文献   

19.
A new red alga, Schmitzia evanescens sp. nov. (Gigartinales), is described from the northeastern coast of North I., New Zealand. Gametophytes are diminutive, delicate, mucilaginous spring annuals which grow subtidally on cobble substrata. The uniaxial construction and carposporophyte development place this new taxon in the Calosiphoniaceae, a family of only two genera, Calosiphonia H. M. Crouan et P. L. Crouan and Schmitzia P. C. Silva. This is the first report of this family in New Zealand. The new species has vegetative features of both these genera, but is assigned to Schmitzia on the basis of its unusual carposporophyte development in which the gonimoblast initial arises directly from the connecting filament at some distance from the undifferentiated intercalary auxiliary cell. Because recent investigators of other red algal genera with a similar carposporophyte development have questioned the validity of site of gonimoblast initiation as a generic criterion it is suggested that the separation of Schmitzia and Calosiphonia should be re-evaluated. These and several other genera in the Gymnophlaeaceae, Pseudoanemoniaceae, Dumontiaceae and Gloiosiphoniaceae, can be considered, on morphological and reproductive grounds, to be relatively simple and therefore perhaps primitive members of the Rhodophyta.  相似文献   

20.
A new foliose red alga, common subtidally from British Columbia to the Aleutian Islands, is described and given the name Hommersandia maximicarpa. The lobed perennial thallus, which can reach a height of 23 cm, is distinguished by its vegetative structure and by its unique pattern of nonprocarpic carposporophyte development. In transverse section, the blades consist of a narrow filamentous medullary layer sandwiched on either side by large ellipsoidal subcortical cells and a thin outer cortex. The monocarpogonial branch and auxiliary cell systems of the female plants are typical of many members of the Kallymeniaceae. However, after the carpogonialfusion cell forms, a distinctive developmental pattern begins. The connecting filaments radiate outward into the surrounding tissue, branch abundantly, and become septate. They then contact, in addition to auxiliary cells, many small moniliform accessory branches. These branches appear to act as initiation points for the gonimoblast filaments. The large diffuse carposporophytes produced are unknown in any other member of the Cryptonemiales. The vegetative and reproductive anatomy of Hommersandia is compared to other Kallymeniaceae, and similar patterns of postfertilization development are examined in the Rhodophyta.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号