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1.
Caroline K. Cusack Stephen S. Bates Michael A. Quilliam John W. Patching Robin Raine 《Journal of phycology》2002,38(6):1106-1112
A nonaxenic isolate of the potentially toxic diatom Pseudo‐nitzschia australis (Frenguelli) from Irish waters was tested in two separate batch culture experiments. When grown under a low irradiance (~12 μmol photons·m ? 2·s ? 1 1 Received 20 March 2001. Accepted 21 August 2002.
; 16:8‐h light:dark cycle) for up to 40 days, the culture produced only trace amounts of the neurotoxin domoic acid (DA) during late stationary phase. Growth at a higher irradiance (~115 μmol photons·m ? 2·s ? 1 1 Received 20 March 2001. Accepted 21 August 2002.
; 12:12‐h light:dark cycle) resulted in DA production starting during late exponential phase and reaching a maximum concentration of 26 pg DA·cell ? 1 1 Received 20 March 2001. Accepted 21 August 2002.
during late stationary phase. Liquid chromatography coupled to mass spectrometry was used to confirm the identity of DA in the culture. Irradiance and photoperiod could be important factors that contribute directly or indirectly to the control of DA production in P. australis. This is the first record of a DA‐producing diatom in Irish waters, and results indicate P. australis may have been the source of DA that has recently contaminated shellfisheries in this area. 相似文献
; 16:8‐h light:dark cycle) for up to 40 days, the culture produced only trace amounts of the neurotoxin domoic acid (DA) during late stationary phase. Growth at a higher irradiance (~115 μmol photons·m ? 2·s ? 1 1 Received 20 March 2001. Accepted 21 August 2002.
; 12:12‐h light:dark cycle) resulted in DA production starting during late exponential phase and reaching a maximum concentration of 26 pg DA·cell ? 1 1 Received 20 March 2001. Accepted 21 August 2002.
during late stationary phase. Liquid chromatography coupled to mass spectrometry was used to confirm the identity of DA in the culture. Irradiance and photoperiod could be important factors that contribute directly or indirectly to the control of DA production in P. australis. This is the first record of a DA‐producing diatom in Irish waters, and results indicate P. australis may have been the source of DA that has recently contaminated shellfisheries in this area. 相似文献
2.
Achnanthes longipes Ag. is a marine stalk‐forming diatom that grows in dense biofilms. The effects of cell density, temperature, and light on growth and stalk production were examined in the laboratory to determine how they affected the ability of this diatom to form a biofilm. Stalk production abruptly increased when A. longipes was cultured at a density of 5.4 × 103 cells·mL ? 1 1 Received 23 February 2002. Accepted 22 July 2002.
, with a lag before stalk production occurring in cultures initiated at lower densities. Growth occurred at all temperatures from 8 to 32° C, with maximum growth at 26° C. Growth rate was light saturated at 60 μmol photons·m ? 2·s ? 1 1 Received 23 February 2002. Accepted 22 July 2002.
. Stalk production was determined as the proportion of cells producing stalks and stalk length in response to various temperatures and light intensities at high (5000 cells·mL ? 1 1 Received 23 February 2002. Accepted 22 July 2002.
) and low (500 cells·mL ? 1 1 Received 23 February 2002. Accepted 22 July 2002.
) densities. More cells formed stalks at high density, with no difference in stalk length. The proportion of cells producing stalks was maximal at 20° C, with little change at 17–32° C. Stalk length was at a maximum between 14 and 26° C. Stalk production showed little change in response to varying light intensity. The results of an earlier investigation on the effects of bromide concentration on stalk formation were expressed as the proportion of cells forming stalks and the lengths of the stalks. Both measures of stalk production varied with bromide concentration, with maximum values at 30 mM bromide. The increased stalk production at higher densities may be a means of elevating cells above the substrate to avoid competition in the dense biofilm. 相似文献
, with a lag before stalk production occurring in cultures initiated at lower densities. Growth occurred at all temperatures from 8 to 32° C, with maximum growth at 26° C. Growth rate was light saturated at 60 μmol photons·m ? 2·s ? 1 1 Received 23 February 2002. Accepted 22 July 2002.
. Stalk production was determined as the proportion of cells producing stalks and stalk length in response to various temperatures and light intensities at high (5000 cells·mL ? 1 1 Received 23 February 2002. Accepted 22 July 2002.
) and low (500 cells·mL ? 1 1 Received 23 February 2002. Accepted 22 July 2002.
) densities. More cells formed stalks at high density, with no difference in stalk length. The proportion of cells producing stalks was maximal at 20° C, with little change at 17–32° C. Stalk length was at a maximum between 14 and 26° C. Stalk production showed little change in response to varying light intensity. The results of an earlier investigation on the effects of bromide concentration on stalk formation were expressed as the proportion of cells forming stalks and the lengths of the stalks. Both measures of stalk production varied with bromide concentration, with maximum values at 30 mM bromide. The increased stalk production at higher densities may be a means of elevating cells above the substrate to avoid competition in the dense biofilm. 相似文献
3.
Adam Kustka Sergio Saudo‐Wilhelmy Edward J. Carpenter Douglas G. Capone John A. Raven 《Journal of phycology》2003,39(1):12-25
Estimates of the iron use efficiency (IUE) for diazotrophic plant growth have been used to suggest iron limitation of marine N2 fixation. However, in the course of these inferences, neither the physiological complexity of these estimates nor the specific physiological parameters of marine diazotrophs were evaluated. Here, a semiempirical prediction of the IUE of diazotrophic growth for Trichodesmium was computed from considerations of the Fe content and reaction rates of the nitrogenase complex and PSI:PSII ratios, as well as field measurements of Mehler activity, cellular Fe‐superoxide dismutase activity, and diel variability in C and N2 fixation. With a PSI:PSII ratio of 1 and 48% Mehler activity, the instantaneous IUE (0.33 mol C fixed·mol cellular Fe ? 1 1 Received 16 August 2001. Accepted 7 October 2002. ·s ? 1 1 Received 16 August 2001. Accepted 7 October 2002. ) was only 4‐fold lower than that calculated for a phytoplankter growing on reduced N. We computed a range of daily integrated IUE values from 2900 to 7700 mol C·mol Fe ? 1 1 Received 16 August 2001. Accepted 7 October 2002. ·d ? 1 1 Received 16 August 2001. Accepted 7 October 2002. , accounting for the diel variability in C and N2 fixation as well as the uncertainties in cyanobacterial nitrogenase biochemistry and PSI:II ratios of field‐collected Trichodesmium. The lowest observed Fe‐superoxide dismutase:C quota of 2.9 (μmol:mol) suggests a maintenance requirement for this enzyme. The maintenance Fe:C requirement of 13.5 μmol:mol (derived from cultures of Trichodesmium IMS 101) and values of the IUE yielded an Fe requirement ranging from 27 to 48 Fe:C (μmol:mol) to achieve a diazotrophic growth rate of 0.1 d ? 1 1 Received 16 August 2001. Accepted 7 October 2002. . Based on these predicted requirements, the Fe:C contents of Caribbean Sea and most North Atlantic Ocean populations sampled thus far exceed that required to support the observed rates of N2 fixation. 相似文献
4.
5.
Following Bernheim, 1 1 J.L. Bernheim. How to get serious answers to the serious question: ‘How have you been?’ Subjective quality of life (QOL) as an individual experiential emergent construct. Bioethics. 1998 ; 13 : 272 – 287 .
we examine aspects of ‘felicitometrics,’ 2 2 Jeremy Bentham (1748–1832) introduced the term ‘felicitometrics.’ He used the term ‘felicific calculus’ to describe methods for calculating the amounts of pleasure and pain consequent on particular courses of action: to wit, ‘Sum up all the values of all the pleasures on the one side and those of all the pains on the other. The balance, if it be on the side of pleasure, will give the good tendency of the act . . .’
the measurement of the ‘quality’ term in Quality of Life (QOL). Bernheim argued that overall QOL is best captured as the Gestalt 3 3 Gestalts are unified wholes with the property that the arrangement of component features provides information not apparent in the features alone. The face provides an oft‐used example: Only by seeing the individual features of the face can one see the face as a whole, and only by seeing the face as a whole can one give meaning to its individual features.
of a global self‐assessment and suggested that the Anamnestic Comparative Self Assessment (ACSA) approach, in which subjects' memories of the best and worst times of their lives are used to anchor a Visual Analog Scale (VAS), provided a serious answer to the serious question, ‘How have you been?’ Bernheim compares and contrasts the ACSA to multi‐item questionnaire QOL instruments, such as the SF‐36, concluding that the ACSA has a number of advantages. His discussion assumes that the use of QOL outcomes in clinical trials is both relevant and appropriate. In the present paper, we document the reasonableness of this latter assumption, 4 4 We emphasize that the choice of the outcome variable in clinical trials has ethical relevance, and that ethical considerations are paramount in choosing length of life and/or quality of life as primary, or at least secondary, outcomes.
contribute to the characterization of the similarities and differences between multi‐item and individualized QOL instruments, and point to some other individualized instruments that may be used in clinical trial contexts. These ‘other individualized instruments’ differ from the ACSA in fundamental ways; but they are individualized in that the subject defines those areas in his/her life that are most important, and these may vary from subject‐to‐subject. 相似文献
we examine aspects of ‘felicitometrics,’ 2 2 Jeremy Bentham (1748–1832) introduced the term ‘felicitometrics.’ He used the term ‘felicific calculus’ to describe methods for calculating the amounts of pleasure and pain consequent on particular courses of action: to wit, ‘Sum up all the values of all the pleasures on the one side and those of all the pains on the other. The balance, if it be on the side of pleasure, will give the good tendency of the act . . .’
the measurement of the ‘quality’ term in Quality of Life (QOL). Bernheim argued that overall QOL is best captured as the Gestalt 3 3 Gestalts are unified wholes with the property that the arrangement of component features provides information not apparent in the features alone. The face provides an oft‐used example: Only by seeing the individual features of the face can one see the face as a whole, and only by seeing the face as a whole can one give meaning to its individual features.
of a global self‐assessment and suggested that the Anamnestic Comparative Self Assessment (ACSA) approach, in which subjects' memories of the best and worst times of their lives are used to anchor a Visual Analog Scale (VAS), provided a serious answer to the serious question, ‘How have you been?’ Bernheim compares and contrasts the ACSA to multi‐item questionnaire QOL instruments, such as the SF‐36, concluding that the ACSA has a number of advantages. His discussion assumes that the use of QOL outcomes in clinical trials is both relevant and appropriate. In the present paper, we document the reasonableness of this latter assumption, 4 4 We emphasize that the choice of the outcome variable in clinical trials has ethical relevance, and that ethical considerations are paramount in choosing length of life and/or quality of life as primary, or at least secondary, outcomes.
contribute to the characterization of the similarities and differences between multi‐item and individualized QOL instruments, and point to some other individualized instruments that may be used in clinical trial contexts. These ‘other individualized instruments’ differ from the ACSA in fundamental ways; but they are individualized in that the subject defines those areas in his/her life that are most important, and these may vary from subject‐to‐subject. 相似文献
6.
Fuscaldo G 《Bioethics》2006,20(2):64-76
Does genetic relatedness define who is a mother or father and who incurs obligations towards or entitlements over children? While once the answer to this question may have been obvious, advances in reproductive technologies have complicated our understanding of what makes a parent. In a recent publication Bayne and Kolers argue for a pluralistic account of parenthood on the basis that genetic derivation, gestation, extended custody and sometimes intention to parent are sufficient (but not necessary) grounds for parenthood. 1 1 Bayne, T. & Kolers, A. . Toward A Pluralist Account of Parenthood . Bioethics 2003 ; 17 : 221 – 242 .
Bayne and Kolers further suggest that definitions of parenthood are underpinned by the assumption that ‘being causally implicated in the creation of a child is the key basis for being its parent’. 2 2 Ibid. p. 241.
This paper examines the claim that genetic relatedness is sufficient grounds for parenthood based on a causal connection between genetic parents and their offspring. I argue that parental obligations are about moral responsibility and not causal responsibility because we are not morally accountable for every consequence to which we causally contribute. My account includes the conditions generally held to apply to moral responsibility, i.e. freedom and foreseeability. I argue that parental responsibilities are generated whenever the birth of a child is a reasonably foreseeable consequence of voluntary actions. I consider the implications of this account for third parties involved in reproductive technologies. I argue that under some conditions the obligations generated by freely and foreseeably causing a child to exist can be justifiably transferred to others. 相似文献
Bayne and Kolers further suggest that definitions of parenthood are underpinned by the assumption that ‘being causally implicated in the creation of a child is the key basis for being its parent’. 2 2 Ibid. p. 241.
This paper examines the claim that genetic relatedness is sufficient grounds for parenthood based on a causal connection between genetic parents and their offspring. I argue that parental obligations are about moral responsibility and not causal responsibility because we are not morally accountable for every consequence to which we causally contribute. My account includes the conditions generally held to apply to moral responsibility, i.e. freedom and foreseeability. I argue that parental responsibilities are generated whenever the birth of a child is a reasonably foreseeable consequence of voluntary actions. I consider the implications of this account for third parties involved in reproductive technologies. I argue that under some conditions the obligations generated by freely and foreseeably causing a child to exist can be justifiably transferred to others. 相似文献
7.
Robert Baker 《Bioethics》2014,28(4):166-169
In ‘New Threats to Academic Freedom’ 1 1 Minerva, F. . New Threats to Academic Freedom . Bioethics 2013 ; DOI: 10.1111/bioe.12066 .
Francesca Minerva argues that anonymity for the authors of controversial articles is a prerequisite for academic freedom in the Internet age. This argument draws its intellectual and emotional power from the author's account of the reaction to the on‐line publication of ‘ After‐birth abortion: why should the baby live?’ 2 2 Giubilini, A. & Minerva, F. . After‐birth Abortion. Why Should the Baby Live? J Med Ethics 2013 ; 39 : 261 – 263 .
– an article that provoked cascades of hostile postings and e‐mails. Reflecting on these events, Minerva proposes that publishers should offer the authors of controversial articles the option of publishing their articles anonymously. This response reviews the history of anonymous publication and concludes that its reintroduction in the Internet era would recreate problems similar to those that led print journals to abandon the practice: corruption of scholarly discourse by invective and hate speech, masked conflicts of interest, and a diminution of editorial accountability. It also contends that Minerva misreads the intent of the hostile e‐mails provoked by ‘After‐birth abortion,’ and that ethicists who publish controversial articles should take responsibility by dialoguing with their critics – even those whose critiques are emotionally charged and hostile. 相似文献
Francesca Minerva argues that anonymity for the authors of controversial articles is a prerequisite for academic freedom in the Internet age. This argument draws its intellectual and emotional power from the author's account of the reaction to the on‐line publication of ‘ After‐birth abortion: why should the baby live?’ 2 2 Giubilini, A. & Minerva, F. . After‐birth Abortion. Why Should the Baby Live? J Med Ethics 2013 ; 39 : 261 – 263 .
– an article that provoked cascades of hostile postings and e‐mails. Reflecting on these events, Minerva proposes that publishers should offer the authors of controversial articles the option of publishing their articles anonymously. This response reviews the history of anonymous publication and concludes that its reintroduction in the Internet era would recreate problems similar to those that led print journals to abandon the practice: corruption of scholarly discourse by invective and hate speech, masked conflicts of interest, and a diminution of editorial accountability. It also contends that Minerva misreads the intent of the hostile e‐mails provoked by ‘After‐birth abortion,’ and that ethicists who publish controversial articles should take responsibility by dialoguing with their critics – even those whose critiques are emotionally charged and hostile. 相似文献
8.
Stephanodscus invisitatus Hohn 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. 2 2 Note added in proof . The authors endorse the terminology of G. R. Hasle (1972, Beih. Nova Hedw., 39 :55–78.) in which the designation strutted tubulus has been employed for the structure referred herein as tube or tube-like process.
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9.
Brain ganglioside patterns of vertebrates 总被引:6,自引:6,他引:0
N F Avrova 《Journal of neurochemistry》1971,18(4):667-674
Abstract— The ganglioside content in brains of representatives of six vertebrate classes (lamprey, ray, sheat-fish, carp, frog, triton, tortoise, hen, pigeon, rabbit, rat and monkey) was determined. In most cases a correlation was found between the level of nervous organization and the ganglioside content of brain. In fish and amphibian brain ganglioside concentration is half to one third that in mammalian brain. Ganglioside composition of higher vertebrate brains (mammals, birds and reptiles) has many similar features. Four main gangliosides with 1-3 NANA residues in their molecules–G1 * * Nomenclature of Korey and Gonatas (1963 ): G1 trisialyl-hexosaminyl-trihexosyl-ceramide; G2 and G3, disialyl-hexosaminyl-trihexosyl-ceramides; G4 monosialyl-hexosaminyl-trihexosyl-ceramide.
, G2, G3 and G4–constitute 80-90 per cent of total ganglioside NANA. Fractions G2a ? ? Go, tetrasialyl-hexosaminyl-trihexosyl-ceramide; G2a disialyl-hexosaminyl-dihexosyl-ceramide; G5, monosialyl-hexosaminyl-dihexosyl-ceramide.
Go and G5 are present in much lesser amounts. Species peculiarities in distribution of NANA among different fractions were noted. The brain gangliosides of lower vertebrates–fish and amphibia–are unusual in having a high proportion of polysialogangliosides, containing 4 and 5 NANA residues, and a lower content of monosialogangliosides. In ray brain a considerable part of gangliosides has a reduced carbohydrate chain. 相似文献
, G2, G3 and G4–constitute 80-90 per cent of total ganglioside NANA. Fractions G2a ? ? Go, tetrasialyl-hexosaminyl-trihexosyl-ceramide; G2a disialyl-hexosaminyl-dihexosyl-ceramide; G5, monosialyl-hexosaminyl-dihexosyl-ceramide.
Go and G5 are present in much lesser amounts. Species peculiarities in distribution of NANA among different fractions were noted. The brain gangliosides of lower vertebrates–fish and amphibia–are unusual in having a high proportion of polysialogangliosides, containing 4 and 5 NANA residues, and a lower content of monosialogangliosides. In ray brain a considerable part of gangliosides has a reduced carbohydrate chain. 相似文献
10.
An effective glucosidase inhibitor was isolated from the cyanobacterial genus Cylindrospermum. Its chemical structure was determined by MS and NMR spectrometry to be di(hydroxymethyl)dihydroxypyrrolidine (DMDP; 2(R),5(R)‐bis‐(hydroxymethyl)‐3(R), 4(R)‐dihydroxypyrrolidine). Its identity was established by comparison with an authentic compound. All five species of Cylindrospermum investigated synthesized this compound but accumulated it to a different extent intracellularly. Particularly active producers were the axenic C. licheniforme (22 pmol·nmol chl a ? 1 1 Received 5 March 2002. Accepted 2 October 2002. ) and a monoxenic unknown species of Cylindrospermum that contained the maximum amount (159 pmol·nmol chl a ? 1 1 Received 5 March 2002. Accepted 2 October 2002. ). The major part of DMDP was found to be extracellular for all species investigated. The isolated compound inhibited digestive α‐ and β‐glucosidases isolated from crustacean zooplankton (IC50 19 and 49 nM, respectively). The bacterial 1‐deoxynojirimycin, which was used as a well‐studied reference glucosidase inhibitor, was less inhibitory (IC50 520 and 2190, respectively). Digestive enzymes of macrozoobenthos (chironomids, trichoptera, and ephemeroptera) were less sensitive to DMDP. The insect digestive β‐glucosidase was more effectively inhibited than the α‐glucosidase. Beside others, the ecological function of the glucosidase inhibitor may be the reduction of the digestibility of the cyanobacterium for grazers. 相似文献
11.
To better understand the interactions between PAR and UV‐B radiation in microalgae, the marine chlorophyte alga Dunaliella tertiolecta was subjected to a UV‐B flux of 4.1 W·m ? 2 (unweighted) with varying PAR fluxes. Rate constants for damage and repair processes during UV‐B exposure increased with PAR flux. However, recovery after UV‐B exposure increased with PAR up to 300 μmol quanta·m ? 2·s ? 1 1 Received 17 September 2002. Accepted 19 February 2003. , beyond which photoinhibition of PSII electron transport was found to decrease recovery rates. In the absence of PAR during the post UV‐B exposure period, no recovery was seen, indicating that perhaps the lack of light available for photosynthesis depresses repair either directly or indirectly by affecting ATP synthesis. Possible mechanisms for the observed interactions between PAR and UV‐B exposure are discussed. 相似文献
12.
H. C. Kitchener 《Cytopathology》2003,14(Z1):3-3
The success of the Cervical Screening Programme (CSP) is due in part to its management being underpinned by Quality Assurance. These measures ensure uniform standards across the country. Since 1992 Colposcopy Guidelines have been in place; these were updated in 1997 and have just been redefined. It is entirely consistent with the National CSP that colposcopy is governed by Guidelines. The aim of clinical practice guidelines is to raise the standard of care and improve outcomes. The objectives are, therefore:
- a) to develop evidence based guidelines;
- b) to ensure the guidelines are widely adopted.
13.
Recruitment of Microcystis from sediments to the water column was investigated in shallow (1–2 m) and deep (6–7 m) areas of Lake Limmaren, central Sweden. Recruitment traps attached to the bottom were sampled on a weekly basis throughout the summer season ( June–September). A comparison between the two sites showed that the recruitment from the shallow bay was significantly higher over the entire season for all three Microcystis species present in the lake. Maximum rates of recruitment were found in August, when 2.3 × 105 colonies m ? 2·day ? 1 1 Received 18 April 2002. Accepted 29 October 2002. left the sediments of the shallow area. Calculated over the entire summer, Microcystis colonies corresponding to 50% of the initial abundance in the surface sediments were recruited in the shallow bay, whereas recruitment from the deep area was only 8% of the sediment colonies. From these results we conclude that shallow areas, which to a large extent have been overlooked in studies of recruitment of phytoplankton, may be crucial to the dynamics of these organisms by playing an important role as inoculation sites for pelagic populations. 相似文献
14.
Libertad García‐Villada Victoria Lpez‐Rodas Elena Baares‐Espaa Antonio Flores‐Moya Mar Agrelo Luis Martín‐Otero Eduardo Costas 《Journal of phycology》2002,38(6):1074-1081
The increasing rates of global extinction due to human activities necessitate studies of the ability of organisms to adapt to the new environmental conditions resulting from human disturbances. We investigated the evolutionary adaptation of a microalga to sudden environmental change resulting from exposure to novel toxic chemical residues. A laboratory strain of Dictyosphaerium chlorelloides (Naum.) Kom. and Perm. (Chlorophyceae) was exposed to increasing concentrations of the modern contaminant 2,4,6‐trinitrotoluene (TNT). When algal cultures were exposed to 30 mg·L ? 1 1 Received 9 July 2001. Accepted 23 July 2002.
TNT, massive lysis of microalgal cells was observed. The key to understanding the evolution of microalgae in such a contaminated environment is to characterize the TNT‐resistant variants that appear after the massive lysis of the TNT‐sensitive cells. A fluctuation analysis demonstrated unequivocally that TNT did not facilitate the appearance of TNT‐resistant cells; rather it was found that TNT‐resistant cells appeared spontaneously by rare mutations under nonselective conditions, before exposure to TNT. The estimated mutation rate was 1.4 × 10 ? 5 mutants per cell division. Isolated resistant mutants exhibited a diminished fitness in the absence of TNT. Moreover, the gross photosynthetic rate of TNT‐resistant mutants was significantly lower than that of wild‐type cells. Competition experiments between resistant mutants and wild‐type cells showed that in small populations, the resistant mutants were driven to extinction. The balance between mutation rate and the rate of selective elimination determines the occurrence of about 36 TNT‐resistant mutants per million cells in each generation. These scarce resistant mutants are the guarantee of potential for adaptation. 相似文献
TNT, massive lysis of microalgal cells was observed. The key to understanding the evolution of microalgae in such a contaminated environment is to characterize the TNT‐resistant variants that appear after the massive lysis of the TNT‐sensitive cells. A fluctuation analysis demonstrated unequivocally that TNT did not facilitate the appearance of TNT‐resistant cells; rather it was found that TNT‐resistant cells appeared spontaneously by rare mutations under nonselective conditions, before exposure to TNT. The estimated mutation rate was 1.4 × 10 ? 5 mutants per cell division. Isolated resistant mutants exhibited a diminished fitness in the absence of TNT. Moreover, the gross photosynthetic rate of TNT‐resistant mutants was significantly lower than that of wild‐type cells. Competition experiments between resistant mutants and wild‐type cells showed that in small populations, the resistant mutants were driven to extinction. The balance between mutation rate and the rate of selective elimination determines the occurrence of about 36 TNT‐resistant mutants per million cells in each generation. These scarce resistant mutants are the guarantee of potential for adaptation. 相似文献
15.
Melissa R. McQuoid 《Journal of phycology》2002,38(5):881-893
The distribution of viable diatom resting stages in sediments on the Swedish west coast was assessed by the most probable number (MPN) culture technique. Multivariate analyses correlated benthic and pelagic environmental factors to the observed spatial variations in the size and taxonomic composition of the propagule bank. Viable diatom resting stages were plentiful (0.2–4.8 million cells·g ? 1 1 Received 11 September 2001. Accepted 12 June 2002.
dry weight) and were dominated by the genera Skeletonema, Detonula, Chaetoceros, and Thalassiosira. Size of the propagule bank was primarily related to planktonic biomass (measured as chl a) and was highest in the Orust‐Tjörn fjord system. Species composition in this fjord system was dominated by D. confervacea (Cleve) Gran and T. nordenskioeldii Cleve in contrast to stations on the outer coast, which contained more cells of T. minima Gaarder, Asterionellopsis glacialis (Castracane) Round, and Leptocylindrus danicus Cleve. These taxonomic variations were principally influenced by deep water oxygen concentrations and water column stability. Benthic resting cells of S. costatum (Greville) Cleve were abundant all along the coast but showed reduced viability in low oxygen environments. Calculations based on MPN values estimated that resuspension of sediment could provide a sizable inoculum to the plankton, although the development of planktonic blooms will also depend on forces of hydrography and weather. Although benthic resting stages may not be absolutely necessary for survival of all diatoms, these cells may be important in determining species cycles, succession, and the spatial distribution of diatoms. 相似文献
dry weight) and were dominated by the genera Skeletonema, Detonula, Chaetoceros, and Thalassiosira. Size of the propagule bank was primarily related to planktonic biomass (measured as chl a) and was highest in the Orust‐Tjörn fjord system. Species composition in this fjord system was dominated by D. confervacea (Cleve) Gran and T. nordenskioeldii Cleve in contrast to stations on the outer coast, which contained more cells of T. minima Gaarder, Asterionellopsis glacialis (Castracane) Round, and Leptocylindrus danicus Cleve. These taxonomic variations were principally influenced by deep water oxygen concentrations and water column stability. Benthic resting cells of S. costatum (Greville) Cleve were abundant all along the coast but showed reduced viability in low oxygen environments. Calculations based on MPN values estimated that resuspension of sediment could provide a sizable inoculum to the plankton, although the development of planktonic blooms will also depend on forces of hydrography and weather. Although benthic resting stages may not be absolutely necessary for survival of all diatoms, these cells may be important in determining species cycles, succession, and the spatial distribution of diatoms. 相似文献
16.
Consent, commodification and benefit-sharing in genetic research 总被引:2,自引:0,他引:2
Dickenson D 《Developing world bioethics》2004,4(2):109-124
The global value of the biotechnology industry is now estimated at 17 billion dollars, with over 1300 firms involved as of the year 2000. 2 2 Holland, S . Contested Commodities at Both Ends of Life: Buying and Selling Gametes, Embryos and Body Tissues . Kennedy Institute of Ethics Journal 2001 ; 11 : 263 – 284 .
It has been said that ‘What we are witnessing is nothing less than a new kind of gold rush, and the territory is the body.’ As in previous gold rushes, prospectors are flooding into unexplored and ‘wide open’ territories from all over the world, with possible ramifications for exploitation of Third World populations. These territories are also the Wild West of bioethics insofar as the law has very little hold on them: existing medical and patent law, such as the Moore and Chakrabarty cases, exert little control over powerful economic interests in both the United States and Europe. In the absence of a unified and consistent law on property in the body, the focus is increasingly on refining the consent approach to rights in human tissue and the human genome, with sensitive and promising developments from the Human Genetics Commission and the Department for International Development consultation on intellectual property. These developments incorporate the views of vulnerable genetic communities such as Native Americans or some Third World populations, and should be welcomed because they recognise the power imbalance between such groups and First World researchers or firms. However, they also highlight the continued tension about what is really wrong with commodifying human tissue or the human genome. Where’s the injustice, and can it be solved by a more sophisticated consent procedure? 相似文献
It has been said that ‘What we are witnessing is nothing less than a new kind of gold rush, and the territory is the body.’ As in previous gold rushes, prospectors are flooding into unexplored and ‘wide open’ territories from all over the world, with possible ramifications for exploitation of Third World populations. These territories are also the Wild West of bioethics insofar as the law has very little hold on them: existing medical and patent law, such as the Moore and Chakrabarty cases, exert little control over powerful economic interests in both the United States and Europe. In the absence of a unified and consistent law on property in the body, the focus is increasingly on refining the consent approach to rights in human tissue and the human genome, with sensitive and promising developments from the Human Genetics Commission and the Department for International Development consultation on intellectual property. These developments incorporate the views of vulnerable genetic communities such as Native Americans or some Third World populations, and should be welcomed because they recognise the power imbalance between such groups and First World researchers or firms. However, they also highlight the continued tension about what is really wrong with commodifying human tissue or the human genome. Where’s the injustice, and can it be solved by a more sophisticated consent procedure? 相似文献
17.
Abstract. A vegetation map at scale 1:5 million is presented. * * Attached on the inside of this issue's back cover.
It covers Bangladesh, Burma (Myanmar), India, Cambodia, Laos, Thailand, Vietnam and Sri Lanka and fills a conspicuous gap in the cartography of tropical vegetation, following the publication of vegetation maps of South America, Africa and Malaysia. For conformity, it is presented as one sheet at a scale of 1:5 million. It uses the basic map of the American Geographical Society (1942; bipolar oblique conformal projection) which forms the base for FAO's Soil map of the world. Basic information was obtained from many published maps, unpublished observations and satellite data. The limits of the main vegetation types have been updated with a complete set of Landsat MSS images (369 scenes) with a mosaic of Landsat TM data for 1991 and with recent forest maps from Asia. Nine main vegetation units, which are groups of forest formations, have been identified and mapped, including woodlands, thickets and wooded savannas. Agricultural land has been shown in a uniform pale green colour in order to clearly express the extent of human impacts on woody vegetation. In spite of the necessary oversimplification of the ground data, this map is probably the most explicit expression of the remaining forest stands and of the regression of natural vegetation in the region. It can be considered as a benchmark for future monitoring of tropical vegetation. 相似文献
It covers Bangladesh, Burma (Myanmar), India, Cambodia, Laos, Thailand, Vietnam and Sri Lanka and fills a conspicuous gap in the cartography of tropical vegetation, following the publication of vegetation maps of South America, Africa and Malaysia. For conformity, it is presented as one sheet at a scale of 1:5 million. It uses the basic map of the American Geographical Society (1942; bipolar oblique conformal projection) which forms the base for FAO's Soil map of the world. Basic information was obtained from many published maps, unpublished observations and satellite data. The limits of the main vegetation types have been updated with a complete set of Landsat MSS images (369 scenes) with a mosaic of Landsat TM data for 1991 and with recent forest maps from Asia. Nine main vegetation units, which are groups of forest formations, have been identified and mapped, including woodlands, thickets and wooded savannas. Agricultural land has been shown in a uniform pale green colour in order to clearly express the extent of human impacts on woody vegetation. In spite of the necessary oversimplification of the ground data, this map is probably the most explicit expression of the remaining forest stands and of the regression of natural vegetation in the region. It can be considered as a benchmark for future monitoring of tropical vegetation. 相似文献
18.
Sergi Sabater Teresa Buchaca Jaume Cambra Jordi Catalan Helena Guasch Núria Ivorra Isabel Muoz Enrique Navarro Montserrat Real Anna Romaní 《Journal of phycology》2003,39(3):481-489
The composition of algal species and pigments and the structural and functional characteristics of the algal community were investigated in an acid stream of southwestern Spain, the Río Tinto. The algal community had low diversity and showed few seasonal differences. It was mainly made up of Klebsormidium flaccidum Kütz. (Silva, Mattox & Blackwell) that produced long greenish or purplish filaments, Pinnularia acoricola Hust. (producing brown patches) and Euglena mutabilis Schmitz. The algal filaments made up a consistent biofilm that also included fungal hyphae, iron bacterial sheaths, diatoms, and mineral particles. HPLC analyses on Río Tinto samples showed that undegraded chl accounted for 67% of the total chl in the filamentous patches but were a minority in the brown patch (2.6%). The brown patch had a concentration of carotenoids eight times lower than that observed in the green patch. When chl concentrations were weighted for the proportion of the different patches on the streambed, undegraded chl a accounted for 89.2 mg chl a·m ? 2 of stream surface area (5.4 g C·m ? 2). This high algal biomass was supported by relatively high nutrient concentrations and by a high phosphatase activity (Vmax = 137.7 nmol methylumbelliferyl substrate·cm ? 2·h ? 1 1 Received 15 July 2002. Accepted 17 February 2003. , Km = 0.0045 μM). The remarkable algal biomass in Río Tinto potentially contributed to the bacterial–fungal community and to the macroinvertebrate community and emphasizes the role that the algae may have in the organic matter cycling and energy flow in extreme systems dominated by heterotrophic microorganisms. 相似文献
19.
Fridtjof Schröder 《化学与生物多样性》2014,11(11):1734-1751
The elaboration of new cyclopropanation methods is expected to make selectively new Δ‐compounds 1 1 Throughout this Review, the notation Δ refers to the presence of a cyclopropane ring, i.e., a ‘Δ‐compound’ is defined as a compound that contains a cyclopropyl substituent or a ‘fused cyclopropa’ component, or a ‘spiro‐cyclopropane’ moiety.
available, either as precursors or as new ingredients with superior olfactory impacts. The improvement of cyclopropanation processes through understanding of reaction mechanisms reduces costs and environmental impact. Givaudan is the leading ‘Flavor & Frangrance’ company which successfully brings Δ‐molecules to the market. Javanol®, for example, with its unique performance exemplifies the product of an efficient industrial cyclopropanation of a dienol precursor. Serenolide®, Toscanol®, and Pashminol® are other high‐impact Δ‐fragrance ingredients manufactured at Givaudan. This review describes our journey from advanced Simmons? Smith methodology using Zn carbenoids, to Al‐ and Mg‐mediated cyclopropanation techniques in the context of related alternative cyclopropanation methods for the transfer of the CH2 group onto C?C bonds. The resulting cyclopropane products are themselves interesting substrates for further transformation to other flavor and fragrance compounds.1 Throughout this Review, the notation Δ refers to the presence of a cyclopropane ring, i.e., a ‘Δ‐compound’ is defined as a compound that contains a cyclopropyl substituent or a ‘fused cyclopropa’ component, or a ‘spiro‐cyclopropane’ moiety. 相似文献
available, either as precursors or as new ingredients with superior olfactory impacts. The improvement of cyclopropanation processes through understanding of reaction mechanisms reduces costs and environmental impact. Givaudan is the leading ‘Flavor & Frangrance’ company which successfully brings Δ‐molecules to the market. Javanol®, for example, with its unique performance exemplifies the product of an efficient industrial cyclopropanation of a dienol precursor. Serenolide®, Toscanol®, and Pashminol® are other high‐impact Δ‐fragrance ingredients manufactured at Givaudan. This review describes our journey from advanced Simmons? Smith methodology using Zn carbenoids, to Al‐ and Mg‐mediated cyclopropanation techniques in the context of related alternative cyclopropanation methods for the transfer of the CH2 group onto C?C bonds. The resulting cyclopropane products are themselves interesting substrates for further transformation to other flavor and fragrance compounds.