摘要:

SUMMARYThe physiological and biochemical changes associated with and resulting in adaptation to both sub‐ and supra‐optimal temperatures are presented for the thermophilic cyanophyteSynechococcus lividusCopeland. The optimum temperature for growth was 45 C. An increase in the optimum temperature of photosynthesis from 50 to 55 C was shown for cells grown at the supra‐optimum temperature of 57 C; whereas, cells grown at the sub‐optimal temperature of 35 C exhibited a decrease in the optimal temperature from 50 to 45 C for14CO2uptake. These changes in optimal temperatures are interpreted as adaptive. Associated with the 5 C increase in optimal temperature for photosynthesis was an increase in chlorophyll a, plastoquinone A, and activity of ribulose‐1,5‐diphosphate carboxylase (RuDP carboxylase). However, the increase in the temperature optimum for 57 C grown cells was associated with a reduced O2yield correlated with a reduced ferricyanide photoreduction capacity. RuDP carboxylase activity decreased rapidly above 55 C. Therefore reduced rates above 55 C resulted from damage to ferricyanide reducing systems and reduced RuDP‐carboxylase activity, whereas low photosynthesis rates at sub‐optimal temperatures were probably due to rate limiting effect of low temperatures on RuDP carboxylase activity with no evidence of damage to ferricyanide photor

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1976.tb02842.x

出版商:Blackwell Science Inc    

年代:1976

数据来源: WILEY

摘要:

SUMMARYThe primary nucleus ofBatophora oerstediiJ. Agardh like that of the relatedAcetabularia,undergoes a great increase in size throughout vegetative development. Formation of small secondary nuclei represents an irreversible stage in the development of reproductive structures in the gametangia. Changes observed in the course of the life cycle include: i) an increase from 3 to 200 μm diam, of the nucleus; ii) increase in number of nucleoli; iii) development of the perinuclear region; iv) increased pore density in the nuclear membrane; v) development of chromosomes in the nucleoplasm; vi) formation of secondary nuclei; and, vii) division of secondary nuclei

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1976.tb02843.x

出版商:Blackwell Science Inc    

年代:1976

数据来源: WILEY

摘要:

SUMMARYThe population structure of 4 CaliforniaIridaea cordata(Turner) Bory populations was studied. Random sampling procedures were used to measure seasonal variations in standing crops, density and size‐class distribution of life history stages. The results describe aspects of thein situlife history; a prerequisite to realistically considering the distribution, ecology or life history expressions of an alga. Seasonal fluctuations in density occur only in the juvenile stage, which is initiated during the winter (November to January) predominantly from the basal perennial crusts. Both the gametangial and tetrasporangial stages are present throughout the year. The tetrasporangial stage is dominant in relation to the sexual stages in both density and biomass during most of the year, except spring when the new crop in just maturing and all stages are abundant. Density in nearly constant and observable changes in the populations are due to biomass fluctuations. Seasonal lows in biomass occur during the winter with the majority of thalli in the smaller size‐classes. Growth and maturation culminate in peak summer crops and dominance of the tetrasporangial stage, followed by autumnal senescence and die‐back in winter. Carrageenans analyzed from immature thalli showed a predominance of lambda‐type, previously determined as specific for tetrasporangial plants. This indirect evidence for the tetrasporangial nature of immature plants suggests that dominance of the diploid stage occurred prior to blade development and most likely at the spore level. Alternatively, field results indicate a major contribution and possible replacement of alternation of gametangial and tetrasporangial stage by thallus perennation and vegetative repro

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1976.tb02844.x

出版商:Blackwell Science Inc    

年代:1976

数据来源: WILEY

摘要:

SUMMARYClone cultures of the thermophilic algaPlectonema notatumSchmidle were established from cells collected from the high and low light intensity regions of the algal mat which developed in Jerry Johnson Hot Spring, Idaho. Clones isolated from cither high, or low light intensify zones were grown at light intensities of 8000 and 400 ft‐c. The existence of specialized and genetically fixed sun or shade ecotypes was evidenced, by the ability of low light intensity clones to synthesize more light harvesting chlorophyllawhen grown under low light conditions than the high light clones. High light clones showed light saturation of photosynthesis at higher light intensities with higher carboxylating enzyme activities and less chlorophyllathan low light clones when both were cultured at 8000 ft‐c. These clones displayed infraspecific variation along the light intensity gradient and therefore exist as a mosaic of light, intensity ecoty

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1976.tb02845.x

出版商:Blackwell Science Inc    

年代:1976

数据来源: WILEY

摘要:

SUMMARYThe structure of the tropical oceanic diatomGossleriella tropicaSchütt was examined in the light and electron microscopes. The species is characterized by a primarily poroid valve, surface, it single central labiate process and a unique ring of spines attached to the cingulum. Placement of the genus in the family Rhizosoleniaceae is suggested. AlthoughG. tropicais widely distributed in the world's oceans, it is usually confined to the lower photic zone, salinities of 34.5–35.5% and temperatures of 15–

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1976.tb02846.x

出版商:Blackwell Science Inc    

年代:1976

数据来源: WILEY

摘要:

SUMMARYTwo replicate experiments were conducted to investigate the effect of light intensity on the growth and nutrient uptake ofSkeletonema costatum(Grev.) Cleve in silicate‐limited continuous culture. Each experiment began with 4 identical chemostat cultures ofS. costatumgrowing at the normal laboratory light (0.14 ly · min−1, continuous illumination) under strong silicate limitation. Screens were placed over 3 cultures reducing them to light intensities of 0.042, 0.021 and 0.0018 ly · min−1.Based on growth rules, nutrient uptake rates, cell morphology and chemical composition, the cultures receiving 0.021, and 0.0018 ly · min−1appeared to he light‐limited, whereas the culture recei

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1976.tb02847.x

出版商:Blackwell Science Inc    

年代:1976

数据来源: WILEY

摘要:

SUMMARYA study of communities of attached algae in Lake Mize Florida, wax made during July 1969, July‐August 1970 and April 1971. The substrates exposed during the study included glass slides mid the terrestrial form of the amphibious sedge,Eleocharis baldwinii(Torr.) Chapman. Counts were used to determine the relative abundance and densities of the species present on the 2 substrates under different environmental conditions. Such analyses indicated that at any given lime and place, a number of factors influenced the composition of the periphyton. Generally, lightly adhering, resupinate species attained higher densities on glass slides than filamentous and loosely associated metaphytonic species. The epiphytic flora ofE. baldwiniicontained a large number of both strong attachers and the metaphyton. The vertical range of many attached species was also greater onE. baldwiniithan on glass slide

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1976.tb02848.x

出版商:Blackwell Science Inc    

年代:1976

数据来源: WILEY

摘要:

SUMMARYWhen either cells of the bacterium,Bdellovibrio bacteriovorus(Stolp&Starr), strain 15143, or a heat‐resistant lytic factor derived from these cells is added to viable cultures ofPhormidium luridumvar.olivaceaBoresch all the algal cells underwent gradual lysis. This effect was obtained with a mean initial bdellovibrio:algal cell ratio of 7.5:1. WhenP. luridumwas mixed with the bdellovibrio cultures the algal chlorophyll content showed an 8‐fold decrease. Concomitantly, this interspecies interaction caused, a 75% inhibition of algal photosynthesis after‐4 h. Heat, treatment of theB. bacteriovorusculture supernatant fluid increased its ability to inhibit photosynthesis approximately 14%. Light, microscopy showed pale granules and intracellular spaces to form in theP. luridumwithin 16 h after adding the bdellovibrio lytic factor. Subsequent morphological changes included the development of large intracellular spaces, intercellular spaces, spheroplast formation and finally Complete lysis of the algal

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1976.tb02849.x

出版商:Blackwell Science Inc    

年代:1976

数据来源: WILEY

摘要:

SUMMARYThe thallus ofHarveyella mirabilis(Reinsch) Schmitz&Reinke is composed of vegetative rhizoidal cells growing intrusively between adjacent cells of the red algal hosts(OdonthaliaandRhodomela)and a protruding reproductive pustule. Although primarily composed ofHarveyellacells, host medullary and cortical cells also occur in the emergent pustule. In both tissue regions,Harveyellacells are connected to host cells by secondary pit connections initiated by the host. Direct penetration of host cells by rhizoidal cells ofHarveyellaoccasionally occurs, resulting in host cell death. Degeneration of host medullary cells beneath the pustule may result in a hollow branch and the cortical cells undergo cell division forming a thick palisade layer of randomly associated, photo‐synthetically active cells. It is within these branches that the parasite overwinters vegetatively. Host medullary and cortical cells dispersed in the emergent pustule show few of the degenerative responses noted in host cells adjacent to parasite rhizoidal cells. Rather, host cell division, chloroplast division and photosynthetic assimilation of H14CO−3all increase. Spherical virus‐like solitary bodies (S‐bodies) occur in allHarveyellacells and in all host cells attached toHarveyellaby secondary pit connections. The possibility that these structures may induce the infective response in the host is di

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1976.tb02850.x

出版商:Blackwell Science Inc    

年代:1976

数据来源: WILEY

摘要:

SUMMARYThe chlorophyll a:b ratios measured in several species ofCaulerpaand inBryopsia plumosa(Hudson) C. Ag. gave values close to 2.00 or below. Values obtained forUlva lactucaL. taken from the same site gave a higher value of 2.44, and the sea‐grassHeterozostera tasmanica(Martens ex Aschers) den Hartog a value of 2.98.Although there were changes ina:bratios observed whenCaulerpaplants were, stored for up to 10 days in dim light, the values did not suggest that chlorophylla:bratios were directly controlled by light intensity. It is conducted that thea:bratios described in this paper, are a characteristic of the species themselves and are not a result of their growth in extremely shaded situation

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1976.tb02851.x

出版商:Blackwell Science Inc    

年代:1976

数据来源: WILEY