摘要:

SUMMARYAll the described species and varieties of the genusHaematococcuswere available. After isolation in pure culture they were used studying their nutritional requirements.H. buetschliiandH. droebakensishad already been shown by Droop to need vitamin B12. H. capensistyp., H. capensisvar. borealis,andH. zimbabwiensiswere found to do so also. The 7 strains ofH. pluvi‐alisfrom various localities investigated showed slight physiological deviations, although morphologically they were so similar that they should not be described as varieties.A dilute inorganic nutrient solution with trace elements and iron kept in solution by EDTA was suitable either as such or supplemented with growth‐promoting compounds. The growth was speeded by low concentrations of acetate and by enhancing photosynthesis.No strain ofH. pluvialisabsolutely required cobalamin, although it stimulated. Thiamine had a much more pronounced effect; for some strains it was indispensable. Although the response varies slightly from strain to strain, a luxuriant growth for all was obtained only with acetate and B1, and usually enhanced by B12. A peculiar feature ofH. pluvialisis the catching up of cultures initially retarded by thiamine deficiency (probably due to slow Blsynthesis).WhenH. pluvialismultiplied fast its appearance differed from that considered typical: no red pigment and the cell wall not inflated. In nature it evidently lives under conditions unfavorable for good growth although suitable for survival in competition with other organi

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1975.tb04534.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1975.tb02418.x

出版商:Blackwell Science Inc    

年代:1975

数据来源: WILEY

摘要:

SUMMARYThe developmental cycle ofNostoc muscorum,a nitrogen‐fixing blue‐green alga, is controlled by the spectral quality of illumination. Red light with peak activity at 650 mμ induces development of filaments from a nonfilamentous (aseriate) stage of the life cycle. Red‐light photoinduction is reversed by simultaneous or subsequent exposure to light from a broad band in the green region of the spectrum. Photoreversibility of the red‐light induction, by green light, decays very slowly, remaining at an appreciable level for over 24 hr after the primary stimulus.Allophycocyanin is indicated to be the photoreceptor for red‐light induction. One or more phycoeythrins may operate as photoreceptors for reversal of induction.The dosage response and wavelength dependence of developmental photocontrol inNostoc muscorumA indicate that a nonphotosynthetic mechanism is involved in both developmental photoinduction and its pho

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1975.tb04535.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SUMMARYConditioned seawater, removed by filtration from an exponentially growing mixed phytoplankton population, inhibited the growth of a small inoculum of cells from the same source without reducing the lag period. When the 2 populations, one in exponential growth and the other freshly inoculated, were separated by a filter membrane allowing passage of excreted compounds, the growth rate of the freshly inoculated cells was again depressed but the lag phase was reduced almost as effectively as by the addition of the chelator, EDTA. Thus both inhibitory and stimulatory compounds appear to be excreted by the cells during exponential growth, the stimulatory group, apparently involved with trace metal metabolism, being more labile to degradation.A test was made to determine if the population could be induced to utilize unconditioned water. Even after repeated transfers there was no reduction in the lag period, indicating that the initiation of exponential growth represents a response to excreted conditioning agents (possibly chelating compounds) rather than an adjustment by the population to use unconditioned water.

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1975.tb02745.x

出版商:Blackwell Science Inc    

年代:1975

数据来源: WILEY

摘要:

SUMMARYThe diatom population structure of a salt marsh epiphytic community growing onEnteromorpha intestinaliswas studied at one station throughout the summer. A total of 218 species or varieties were recognized. Six species— Fragilaria construens, Cocconeis scutellum, Cocconeis placentula, Achnanthes hauckianavarieties,Achnanthes pinnata, andAmphora coffeaeformis(var.acutiuscula)–dominated theEnteromorphaepiphytic community during the summer months and comprised ∼ 40% of the total populations.Melosira nummuloides, Opephora martyi, Synedra fasiculatavar.tabulata, S. affinis, Navicula platyventris, andN. pavillardiwere also very common species (13% of the total population). The distribution of many species in the community was seasonal. A series of differential media have been developed which are effective as tools for the isolation and nutritional characterization of the algae and bacteria from the community. Many diatom species can be recognized by their colony type or growth pattern on solidified media. A key and illustrated plates aid in identification. Changes in population structure of the community were reflected by changes in the nutritional patterns as judged by differences in the growth of diatoms and bacteria on the differential media tested. The nutritional requirements, selectivity, and rank order of media for individual species is given.Almost half of the colony types (32–33) grew on either unenriched seawater from the collection site or basal synthetic seawater. Erdschreiber was a poorer medium for the isolation of algae than seawater alone. Few algal colonies grew on either marine nutrient agar or trypticase soy agar. Nitrite inhibited algal growth. Media enriched with thiamine, biotin, or nitrate, phosphate, and B12were stimulatory. Soil extract or an acetone extract ofEnteromorphatripled growth; a complex vitamin mixture, or glycerol, or mannitol, or an autoclaved extract ofEnteromorphadoubled colony numbers. The greatest numbers of diatom types (43) and total colonies (655) were recovered on media enriched with acetone extract ofEnteromorpha, suggesting a possible nutritional relationship betweenEnteromorphaand its epiphytes.The representativeness of the isolations from the natural community as a function of time was also considered. Concentrations of selected dissolved potential growth‐stimulating nutrients were measured within and external toEnteromorphacommunities. We conclude that the algal assemblage growing epiphytically onEnteromorpha intestinalishas a diverse auxotrophic profile which contributes to the productivity and stability within this important component of the epiphytic community and that much of the organic substrates used by individual species originate within and are recycled among the communit

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1975.tb02746.x

出版商:Blackwell Science Inc    

年代:1975

数据来源: WILEY

摘要:

SUMMARYThree species of tropical oceanic phytoplankton were isolated from two locations in the eastern Pacific Ocean. Unialgal cultures were maintained in an enriched seawater medium. The effects of temperature, and, in separate experiments, illuminance, on the exponential cell division rates of those algae were investigated. For 2 isolates ofGymnodiniumsp. (probablyG. simplex),maximum growth rates were 1.25 and 1.7 divisions/24 hr, the optimum temperature range was 23–29 C, the compensation illuminance was 35 ft‐c, and the saturation illuminance was 750 ft‐c and above. For a small species ofChaetoceros,the maximum growth rate was 6.0 divisions/24 hr, the optimum temperature range was 23–37 C, the compensation illuminance was 10 ft‐c, and the saturation illuminance was 600 ft‐c. For a smallNannochlorisspecies, the maximum growth rate was 4.5 divisions/ 24 hr, the optimum temperature range was 27–37 C, and the saturation illuminance was 800 ft‐c. Nannochlorisgrew heterotrophically by apparently utilizing organic matter supplied

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1975.tb04536.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SUMMARYGrowth in defined media of 32 populations ofGonium pectoralewas studied to learn more about the sexual isolation reported for this species. The 23 populations containing both mating types(+&‐)were also studied for the ability to form zygotes in defined media. A preliminary study showed that some populations grew and reproduced sexually in a defined mineral medium, whereas others appeared to require exogenous organic materials for growth and/or zygote formation. The diverse reactions exhibited by the populations indicate physiological races which may explain, in part, the occurrence of sexual isolatio

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1975.tb04537.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SUMMARYThree pelagic marine phytoplankters, Coccolithus huxleyi, Skeletonema costatum,andThalassiosira rotula,and a facultative heterotroph, Cyclotella cryptica,have been exposed to three organic substrates, viz,glucose, acetate, and glutamate, at low concentrations (organic carbon 0.25 mg/liter). Experiments were performed in the dark and light and the net assimilation of substrate was measured by using radiocarbon. The dark uptake of carbon dioxide was also determined, together with photosynthesis at near optimum light intensity. The expected heterotrophy was detected withCyclotella cryptica. Thalassiosira rotulawas found to assimilate glutamate at an appreciable rate. In all cases, however, the short‐term uptake of carbon dioxide in the dark was the greatest assimilation rate measured. Values are discussed in relation to their ecological significance and it is concluded that heterotrophic survival of these and probably most other algae in the open ocean would be impossible unless they were in contact with a high concentration of substrate in the form of particulate matte

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1975.tb04538.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SUMMARYAn extractive Procedure for detection of surplusstored phosphorus (luxury consumption) in algae and an enzymatic analysis for conditions of P‐limited growth in algae have been evaluated. A simple 60‐min boiling water extraction of algae known to contain surplus P separates essential P compounds and surplus‐stored P compounds. Surplus P compounds can be measured in the extract as orthophosphate. Extracts of algae limited in their growth by the amount of available P contain little or no orthophosphate. Limitation of algal growth by P supply induces the enzyme alkaline phosphatase. The activity of this enzyme can be measured at pH 9 using p‐nitro‐phenylphosphate as substrate. Algae which were P‐limited and contained no extractable orthophosphate have as much as 25 times more alkaline phosphatase activity than algae with surplus

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1975.tb04539.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

SUMMARYThe major C14‐labeled substance in sieve tube exudate ofM. pyriferaisD‐mannitol, comprising 3.6% (w/v). No sugars are detectable. Certain amino acids also possess some CWabeling and occur in significantly high concentrations in exudate. The exudate contains negligible ether‐soluble lipid, but has a large amount of protein and a high concentration of K+. Neither protein nor lipid become labeled significantly in sieve tubes during short‐term translocation experiments with C14. In general the chemical composition of the assimilate stream is comparable to that of vascular plants and does not, consequently, necessitate a different mechanism for transl

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1975.tb04540.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY