摘要:

SUMMARYThe fatty acid composition of 10 species of estuarine phytoplankton was determined using gas‐liquid chromatography. Nine of the species were isolated from Yaquina Bay, Oregon. These species were common components of the phytoplankton of the bay. The tenth species,Isochrysis galbana, was obtained from the Culture Collection of Algae at Indiana University. The 10 organisms comprised 3 species of Chlorophyta, 1 species of Cryptophyta, and 6 species of Chrysophyta.Twenty‐eight fatty acids were found in the 10 species. The fatty acids common to all species were 14:0, 16:0, 16:1, 13:0, 18:1, and 18:2. The Chlorophyta were distinguished by a high content of linolenic acid, 18:3. The diatoms were distinguished by very low amounts of C18acids and high proportion of 20:5. All species contained a high proportion of palmitic acid, 1

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1972.tb04030.x

出版商:Blackwell Science Inc    

年代:1972

数据来源: WILEY

摘要:

SUMMARYHalf‐saturation constants for urea uptake by 4 clones of neritic diatoms capable of utilizing urea were determined from short‐term uptake studies with15N‐labeled urea.K8values obtained were similar to those determined, earlier for ammonium, and since ammonium and urea concentrations are similar in the marine environment, it was concluded that these species are capable of utilizing ecologically significant concentrations of urea. Two of 3 species unable to grow on urea showed patterns of short‐term uptake not unlike those of species capable of utilizing urea, which implies that, their assimilatory rather than uptake processes are defective with, regard to urea utilization. The third species initially took15N (supplied as urea) into the cells but subsequently released it back into the

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1972.tb04031.x

出版商:Blackwell Science Inc    

年代:1972

数据来源: WILEY

摘要:

SUMMARYThe marine planktonic diatomCoenobiodiscus muriformishas been reinvestigated using light microscopy and scanning and transmission electron microscopy; as a result it is proposed, to transfer the species to the genusPlanktoniella.The structure and formation of colonies are discussed and compared with data from an earlier study. Further details of valve and girdle baud structure have been ascertained and the exact form of the central and peripheral tubes has been described. The relationship of the present taxon toThalassiosiraandCoscinodiscusis discussed.

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1972.tb04032.x

出版商:Blackwell Science Inc    

年代:1972

数据来源: WILEY

摘要:

SUMMARYThe cell wall ofCosmarium botrytiswas studied through the use of the freeze‐etch technique. The cell wall consists of many thin layers. Fracturing along one layer reveals the positioning of the wall sculpturing, wall pores, and wall microfibrils. The individual microfibrils are grouped together in bands of parallel oriented fibrils. The different bands of parallel microfibrils were apparently arranged at random angles with regard to each other. Small particles may also be present in the cell walls.The cell wall pore unit ofCosmarium botrytiswas studied through the use of scanning, freeze‐etching, and thin sectioning techniques. The pore sheaths, on the outside of the cell wall, form a collar around the mouth of each pore. The pore sheath is composed of needle‐like fibrils radiating outward from the pore. A pore channel traverses the cell wall and leads to a complex pore bulb region between the cell wall and the plasmalemma. The pore bulb contains many small fibrils which radiate toward the plasmalemma from a number of net‐like fibril layers which in turn merge into a very electron dense region near the base of t

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1972.tb04033.x

出版商:Blackwell Science Inc    

年代:1972

数据来源: WILEY

摘要:

SUMMARYThis paper refers to a case of polymorphism in the desmidMicrasterias laticepsNordst. It is based on material collected from an artificial pond in the state of São Paulo, Brazil.A detailed examination of almost 400 specimens permitted the authors to give a detailed description of 13 main morphological forms of the alga and allowed them to draw the following conclusions: (1) For delimitation of genera and infrageneric taxa in desmids it is often necessary to examine sample populations; (2) the morphological characteristics presently used for delimitation of varieties inM. laticepsNordst. seem to have no considerable taxonomic significance if isolated individuals are studied; (3) it is necessary to take into considerationCosmarium arthrodesmiformeBorge andC. arthrodesmiformevar.latiusKrieg.&Gerl., as well asM. laticepsNordst. var.ampliataKrieg., when further studies are undertaken, because they may prove to be merely distinct morphological expressions ofM. laticepsNordst var.laticeps

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1972.tb04034.x

出版商:Blackwell Science Inc    

年代:1972

数据来源: WILEY

摘要:

SUMMARYAt the ultrastructural level, cell division inOchromonas danicaexhibits several unusual features. During interphase, the basal bodies of the 2 flagella replicate and the chloroplast divides by constriction between its 2 lobes. The rhizoplast, which is a fibrous striated root attached to the basal body of the long flagellum, extends under the Golgi body to the surface of the nucleus in interphase cells. During proprophase, the Golgi body replicates, apparently by division, and a daughter rhizoplast, appears. During prophase, the 2 pairs of flagellar basal bodies, each with their accompanying rhizoplast and Golgi body, begin to separate. Three or 4 flagella are already present at this stage. At the same time, there is a proliferation of microtubules outside the nuclear envelope. Gaps then appear in the nuclear envelope, admitting the microtubules into the nucleus, where they form a spindle. A unique feature of mitosis inO. danicais that the 2 rhizoplasts form the poles of the spindle, spindle microtubules inserting directly onto the rhizoplasts. Some of the spindle microtubules extend from pole to pole; others appear to attach to the chromosomes. Kinetochores, however, are not present. The nuclear envelope breaks down, except, in the regions adjacent, to the chloroplasts; chloroplast ER remains intact throughout mitosis. At late anaphase the chromosomes come to lie against part of the chloroplast ER. This segment of the chloroplast ER appears to be incorporated as part of the reforming nuclear envelope, thus reestablishing the characteristic nuclear envelope—chloroplast ER association of the interphase cel

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1972.tb04035.x

出版商:Blackwell Science Inc    

年代:1972

数据来源: WILEY

摘要:

SUMMARYStephanodscus invisitatusHohn and Hellerman, studied by means of light, transmission, and scanning electron microscopy, shows a range of frustule diameters from 6.4 to 13.3 μ. Variation in valve ornamentation can be correlated with specimen diameter. The striae number ranges from 16 to 20 in 10 μ. Various processes difficult to observe by light microscopy alone are described which arise from the inside and outside of the frustules

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1972.tb04036.x

出版商:Blackwell Science Inc    

年代:1972

数据来源: WILEY

摘要:

SUMMARYBiddulphia aurita, a centric diatom, can grow on either nitrate, nitrite, or ammonia as its sole nitrogen, source.Cells remove ammonium nitrogen from the medium 2.3–2.4 times faster than either nitrate or nitrite nitrogen and, when grown for 24 hr in the ammonium medium, contain higher levels of non‐protein nitrogen than cells grown in the nitrate or nitrite medium for the same period of time.The nitrogenous compounds in the nonprotein nitrogen fraction from cells grown in the nitrate, nitrite, or ammonium medium contain the same level of soluble‐free amino nitrogen, combined amino nitrogen, and ammonium nitrogen. The high level of soluble nonprotein nitrogen in the medium of the cells grown in the ammonium medium is due to soluble amide nitrogen which represents 18% of the total soluble nitrogen present in these cells, whereas it represents only 2% in cells from the nitrite medium, and its level is negligible in cells from the nitrate medium.Cells grown in the nitrate medium have both nitrate‐ and nitrite‐reductase activity. Cells grown in the nitrite medium have only nitrite‐reductase activity in significant levels, while cells grown in the ammonium medium lack b

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1972.tb04037.x

出版商:Blackwell Science Inc    

年代:1972

数据来源: WILEY

摘要:

SUMMARYA soluble protein extract, obtained after35S labeling exponential cultures ofCryptothecodinium cohniifor 4–5 generations, was fractionated on DNA‐cellulose. The protein eluted at high salt concentrations from this homologous DNA‐containing matrix was then separated, by chromatography on BioGel P150 and P200 sieve gels. Two prominent chromatographic species of 22,000 and 35,000 daltons plus a substantial amount of material in the molecular weight range of 80,000–140,000 were resolved. The application of this analytical procedure to the study of transcriptional control in the cell cycle is di

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1972.tb04038.x

出版商:Blackwell Science Inc    

年代:1972

数据来源: WILEY

摘要:

SUMMARYChlorella pyrenoidosa, a green alga which has no measurable Ca requirement, tolerated much higher Al concentrations in solution than higher plants which require considerable Ca. This alga also gave significant positive yield responses to Al concentrations between 1.5 and 12 ppm (added at pH 4.6). The positive Al response was not attributable to V, Cr, Ni, Co, W, or Ti contaminants in the Al salt.A strain ofC. pyrenoidosahaving even greater Al tolerance was isolated, by subjecting the original Strain I (Fitzgerald) culture to increasing Al stress. This strain, I‐Al, grew in stagnant cultures containing 48 ppm Al at an initial pH of 4.2. Its yield also was not significantly decreased by 48 ppm Al in aerated cultures when both inoculum and solution pH were 4.6. Under the same conditions the original Strain I organism was injured by 3 and 6 ppm Al and was killed by 12 ppm.Algal strains which differ in Al tolerance may be useful in (1) studies on the mechanism of Al toxicity and mineral nutrition in general; and (2) in raising the pH, precipitating Al, and thereby detoxifying Al‐containing acid mine drainage water and commercial was

ISSN:0022-3646    

DOI:10.1111/j.1529-8817.1972.tb04039.x

出版商:Blackwell Science Inc    

年代:1972

数据来源: WILEY