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131.
Across the world there is a prevailing view that freshwater algae are cosmopolitan. The notion has seldom been tested and
is unlikely to be true in genetic terms. Nonetheless, some morphospecies of several groups of algae do have a worldwide distribution.
Others have restricted distributions and may be regarded as endemic to a region. However there is always the possibility that
they will be discovered in far away places. Australia has a rather large element of endemicity in its algal flora. From the
early days of Australian phycology many new genera and species of freshwater algae have been described. Some are of such distinctive
appearance or novelty as to be regarded as ‘flagship’ taxa. There is little doubt about their endemicity and their existence
increases the probability of less-distinguished species also being endemic. The degree of endemicity is probably masked by
the ‘force-fitting’ of European names to Australian species.
Some Australian endemics are robust and are widely distributed in a variety of types of water body. Others, the frail endemics,
the ones of greatest novelty and phylogenetic significance, have a very restricted range with their strongholds in dystrophic
coastal lagoons where tracts or remnant patches of native vegetation survive. Their survival and the conservation of their
biodiversity depends on recognition of the significance of coastal lagoons and swamps. 相似文献
132.
Louise Warnich Peter N. Meissner Richard J. Hift Jan H. Louw Carel J. van Heerden Andries E. Retief 《Human genetics》1996,97(5):690-692
The gene for variegate porphyria (VP), an autosomal dominant disease with a high prevalence in South Africa, evidently due
to a founder effect, was previously mapped to chromosome 14q32. In the current study this localization was evaluated by linkage
and haplotype analyses using microsatellite markers spanning a region of more than 20 cM on chromosome 14q32. In many recent
studies linkage disequilibrium between disease and marker loci has been utilized to map genes in founder populations, but
we could not find any association between VP and the markers used in this study. Our data suggest that the allocation of VP
to chromosome 14q32 may be incorrect.
Received: 1 September 1995 / Revised: 1 November 1995 相似文献
133.
An De Bondt Kristel Eggermont Iris Penninckx Inge Goderis Willem F. Broekaert 《Plant cell reports》1996,15(7):549-554
We have previously developed a protocol for efficient gene transfer and regeneration of transgenic calli following cocultivation of apple (cv. Jonagold) explants with Agrobacterium tumefaciens (De Bondt et al. 1994, Plant Cell Reports 13: 587–593). Now we report on the optimization of postcultivation conditions for efficient and reproducible regeneration of transgenic shoots from the apple cultivar Jonagold. Factors which were found to be essential for efficient shoot regeneration were the use of gelrite as a gelling agent and the use of the cytokinin-mimicing thidiazuron in the selective postcultivation medium. Improved transformation efficiencies were obtained by combining the hormones thidiazuron and zeatin and by using leaf explants from in vitro grown shoots not older than 4 weeks after multiplication. Attempts to use phosphinothricin acetyl transferase as a selectable marker were not successful. Using selection on kanamycin under optimal postcultivation conditions, about 2% of the leaf explants developed transgenic shoots or shoot clusters. The presence and expression of the transferred genes was verified by -glucuronidase assays and Southern analysis. The transformation procedure has also been succesfully applied to several other apple cultivars.Abbreviations BAP
benzylaminopurine
- CTAB
hexadecyltrimethylammoniumbromide
- Na2EDTA
ethylenediamine-tetra-acetate ferric-sodium salt
- FeNaEDTA
ethylenediamine-tetra-acetate ferric-sodium salt
- GA3
gibberellic acid 3
- GusA
-glucuronidase
-
gusA
-glucuronidase gene of Escherichia coli
- IAA
indole acetic acid
- IBA
indole butyric acid
- 2iP
N6-2-isopentenyl adenine
- NAA
naphthalene acetic acid
-
nptII
neomycinphosphotransferase II gene
-
bar
phosphinothricin acetyl transferase gene
- PCR
polymerase chain reaction
- PPT
phosphinothricin
- STS
silver thiosulphate
- T-DNA
transferred DNA
- TDZ
thidiazuron
- X-Gluc
5-bromo-4-chloro-3-indolyl -D-glucuronide
- Zea
trans-Zeatin 相似文献
134.
Grant E. Brown R. Jan F. Smith 《Ethology : formerly Zeitschrift fur Tierpsychologie》1996,102(5):776-785
Pike-naive fathead minnows (Pimephales promelas) were fed ad libitum or deprived of food for 12, 24, or 48 h and then exposed to either conspecific alarm pheromone or distilled water and the odour of a predatory northern pike (Esox lucius). Minnows fed ad libitum or deprived for 12 h showed a stereotypic alarm response to the alarm pheromone (increased time under cover objects and increased occurrence of dashing and freezing behaviour); those deprived of food for 24 h showed a significantly reduced alarm response, while those deprived of food for 48 h did not differ significantly from the minnows exposed to a distilled water control. Upon subsequent testing in an Opto-Varimex activity meter, all groups initially exposed to alarm pheromone and pike odour exhibited an alarm response when exposed to pike odour alone. Those initially conditioned with distilled water and pike odour did nor show an alarm response to pike odour alone. These results demonstrate that there exists a significant trade-off between hunger level and predator-avoidance behaviour in fathead minnows and that minnows can learn the chemical cues of a predatory northern pike through association with alarm pheromone even in the absence of an observable alarm response. 相似文献
135.
Local renin-angiotensin systems 总被引:6,自引:0,他引:6
A. H. Jan Danser 《Molecular and cellular biochemistry》1996,157(1-2):211-216
The existence of a local cardiovascular renin-angiotensin system (RAS) is often invoked to explain the long-term beneficial effects of RAS inhibitors in heart failure and hypertension. The implicit assumption is that all components of the RAS are synthesized in situ, so that local angiotensin II formation may occur independently of the circulating RAS. Evidence for this assumption however is lacking. The angiotensin release from isolated perfused rat hearts or hindlimbs depends on the presence of renal renin. When calculating the in vivo angiotensin production at tissue sites in humans and pigs, taking into account the extensive regional angiotensin clearance by infusing radiolabeled angiotensin I or II, it was found that angiotensin production correlated closely with plasma renin activity. Moreover, in pigs the cardiac tissue levels of renin and angiotensin were directly correlated with their respective plasma levels, and both in tissue and plasma the levels were undetectably low after nephrectomy. Similarly, rat vascular renin and angiotensin decrease to low or undetectable levels within 48 h after nephrectomy. Aortic renin has a longer half life than plasma renin, suggesting that renin may be bound by the vessel wall. In support of this assumption, both renin receptors and renin-binding proteins have been described. Like ACE, renin was enriched in a purified membrane fraction prepared from cardiac tissue. Binding of renin to cardiac or vascular membranes may therefore be part of a mechanism by which renin is taken up from plasma. It appears that the concept of a local RAS needs to be reassessed. Local angiotensin formation in heart and vessel wall does occur, but depends, at least under normal circumstances, on the uptake of renal renin from the circulation. Tissues may regulate their local angiotensin concentrations by varying the number of renin receptors and/or renin-binding proteins, the ACE level, the amount of metabolizing enzymes and the angiotensin receptor density.Abbreviations RAS
renin-angiotensin system
- ANG
angiotensin
- ACE
angiotensin-converting enzyme
- PRA
plasma renin activity 相似文献
136.
Jan O. Gordeladze Trine Haugen Eivind J. Paulssen Ruth H. Paulssen 《Bioscience reports》1996,16(1):65-74
The presence of the pertussis toxin (PTX) insensitive GTP-binding proteins (G-proteins) Gq and/or G11 has been demonstrated in three different prolactin (PRL) and growth hormone (GH) producing pituitary adenoma cell lines. Immunoblocking of their coupling to hormone receptors indicates that Gq and/or G11 confer throliberin (TRH) responsive phospholipase C (PL-C) activity in these cells. The contention was substantiated by immunoprecipitation analyses snowing that anti Gq/11-sera coprecipitated PL-C activity. In essence, only Gq/11 (but neither Gi2, Gi3 nor Go) seems to mediate the TRH-sensitive PL-C activity, while Go may be coupled to a basal or constitutive PL-C activity. Immunoblocking studies imply that the B-complex also, to some extent, may stimulate GH3 pituitary cell line PL-C activity. Finally, the steady state levels of Gq/11 mRNA and protein were downregulated upon long term exposure of the GH3 cells to TRH (but not to vasoactive intestinal peptide = VIP). 相似文献
137.
Lars Öhman Maria Alarcon Jan Ljunggren Anna-Karin Ramqvist Lena Häggström 《Biotechnology letters》1996,18(7):765-770
Summary
Spodoptera frugiperda (Sf-9) insect cells are fully capable of growth and proliferation in a glutamine, glutamate and aspartate-free medium, provided that ammonium ions are supplied. S. frugiperda (Sf-21) and Mamestra brassicae cells (IZD-MB-0503) also grow in glutamine-free media but not Trichoplusia ni cells (BTI-TN 5B1-4). The yield of -galactosidase in Sf-9 cells infected with a recombinant baculovirus under glutamine-free conditions was even higher than the yield obtained in glutamine containing cultures. 相似文献
138.
Vaughan Hurry Jan M. Anderson Murray R. Badger G. Dean Price 《Photosynthesis research》1996,50(2):159-169
We have examined tobacco transformed with an antisense construct against the Rieske-FeS subunit of the cytochromeb
6
f complex, containing only 15 to 20% of the wild-type level of cytochrome f. The anti-Rieske-FeS leaves had a comparable chlorophyll and Photosystem II reaction center stoichiometry and a comparable carotenoid profile to the wild-type, with differences of less than 10% on a leaf area basis. When exposed to high irradiance, the anti-Rieske-FeS leaves showed a greatly increased closure of Photosystem II and a much reduced capacity to develop non-photochemical quenching compared with wild-type. However, contrary to our expectations, the anti-Rieske-FeS leaves were not more susceptible to photoinhibition than were wild-type leaves. Further, when we regulated the irradiance so that the excitation pressure on photosystem II was equivalent in both the anti-Rieske-FeS and wild-type leaves, the anti-Rieske-FeS leaves experienced much less photoinhibition than wild-type. The evidence from the anti-Rieske-FeS tobacco suggests that rapid photoinactivation of Photosystem II in vivo only occurs when closure of Photosystem II coincides with lumen acidification. These results suggest that the model of photoinhibition in vivo occurring principally because of limitations to electron withdrawal from photosystem II does not explain photoinhibition in these transgenic tobacco leaves, and we need to re-evaluate the twinned concepts of photoinhibition and photoprotection.Abbreviations Chl
chlorophyll
- DCMU
3-(3,4-dichlophenyl)-1,-dimethylurea
- Fo and Fo
minimal fluorescence when all PS II reaction centers are open in dark- and light-acclimated leaves, respectively
- Fm and Fm
maximal fluorescence when all PS II reaction centers are closed in dark- and light-acclimated leaves, respectively
- Fv
variable fluorescence (Fm-Fo) in dark acclimated leaves
- Fv
variable fluorescence (Fm-Fo) in lightacclimated leaves
- NPQ
non-photochemical quenching of fluorescence
- PS I and PS II
Photosystem I and II
- P680
primary electron donor of the reaction center of PS II
- PFD
photosynthetic flux density
- QA
primary acceptor quinone of PS II
- qp
photochemical quenching of fluorescence
- V+A+Z
violaxanthin+antheraxanthin+zeaxanthin 相似文献
139.
Gerben J. Van Eldik Miriam Wingens René K. Ruiter Marinus M. A. Van Herpen Jan A. M. Schrauwen George J. Wullems 《Plant molecular biology》1996,30(1):171-176
A gene, sts14, coding for a highly expressed mRNA in pistils of Solanum tuberosum, was isolated. Northern blot and in situ analyses demonstrated that the gene was expressed throughout pistil development in both the stylar cortex and the stigma. The deduced STS14 protein displays similarity to the pathogenesis-related PR-1 proteins. A possible function for protection or guidance of the pollen tubes through the pistil is discussed. 相似文献
140.
Molecular cloning of the lectin and a lectin-related protein from common Solomon's seal (Polygonatum multiflorum) 总被引:3,自引:0,他引:3
Els J. M. Van Damme Annick Barre Pierre Rougé Fred Van Leuven Jan Balzarini Willy J. Peumans 《Plant molecular biology》1996,31(3):657-672
The most prominent protein ofPolygonatum multiflorum (common Solomon's seal) rhizomes has been identified as a mannose-binding lectin. Analysis of the purified lectin demonstrated that it is a tetramer of four identical subunits of 14 kDa. Molecular cloning further revealed that the lectin from this typical Liliaceae species belongs to the superfamily of monocot mannose-binding proteins. Screening of cDNA libraries constructed with RNA isolated from buds, leaves and flowers ofP. multiflorum also yielded cDNA clones encoding a protein, which contains two tandemly arranged domains with an obvious sequence homology to the mannose-binding lectins. Molecular modelling of thePolygonatum lectin and lectin-related protein indicated that the three-dimensional structure of both proteins strongly resembles that of the snowdrop lectin. In addition, this approach suggested that the presumed carbohydrate-binding sites of the lectin can accommodate a mannose residue whereas most of the carbohydratebinding sites of the lectin-related protein cannot.Abbreviations GNA
Galanthus nivalis agglutinin
- HCA
hydrophobic cluster analysis
- LECPMA
cDNA clone encoding PMA
- PM30
30 kDa protein isolated fromPolygonatum multiforum
- PMA
Polygonatum multiflorum agglutinin
- PMLRP
Polygonatum multiflorum lectin-related protein 相似文献