Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    AMNIOTIC FLUID ACETYLCHOLINESTERASE AND PRENATAL DIAGNOSIS (1980)
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 87 (1980), S. 0 
    Details
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Raised specific acetylcholinesterase (AChE) activity in amniotic fluid was consistently found to be associated with fetal intrauterine death and neural tube defects, but in just under half of the samples from pregnancies with spina bifida, the increase was marginal. Elevated AChE levels were occasionally found in fluid samples contaminated by maternal blood, and in nearly half of the samples which were a brown or yellow-brown colour but where there was a normal fetus. Nine fluids, five of which were contaminated with fetal blood, had a false positive result on alpha-fetoprotein (AFP) assay (elevated AFP levels and a normal fetus), but showed normal AChE activities. It is suggested that AChE estimation might be useful in prenatal diagnosis as a second test for those fluids which have an elevated AFP level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-0528.1980.tb04586.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    POLYACRYLAMIDE GEL ELECTROPHORESIS OF AMNIOTIC FLUID CHOLINESTERASES: A GOOD PRENATAL TEST FOR NEURAL TUBE DEFECTS (1980)
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 87 (1980), S. 0 
    Details
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The qualitative assay of the cholinesterases (ChE) in amniotic fluid on polyacrylamide gel gave a single major band (cholinesterase) in all samples from normal pregnancies, and two major bands (cholinesterase and acetylcholinesterase) in all cases from fetuses with open neural tube defects. Five fluids which were true false positive on alpha-fetoprotein (AFP) assay (elevated AFP in a clear fluid but normal fetus) had a single band, and two fluids which were false negative on AFP testing (normal AFP but spina bifida fetus) had two bands. The second ‘diagnostic’ ChE band sometimes occurred, together with other extra bands, in some fluids which were very severely contaminated by maternal or fetal blood, but in four of six fluids from normal fetuses where fetal blood staining was sufficient to cause the AFP to be elevated, there was only one ChE band. It is suggested that the qualitative assay of ChE should be performed in addition to AFP in the prenatal diagnosis of neural tube defects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-0528.1980.tb04481.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Gonadal structure and population characteristics of the protogynous goby Coryphopterus glaucofraenum (1992)
    Springer
    Marine biology 113 (1992), S. 1-9 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Protogynous hermaphroditism has been reported in two gobiid species within the genus Coryphopterus, including C. nicholsi from the temperate northeastern Pacific and C. personatus from the Caribbean. In a third species from the Caribbean, C. glaucofraenum, experimental groups were established and gonad structure of experimental individuals (collected off the southwest coast of Puerto Rico between February 1985 and June 1987) was subsequently examined histologically to determine the sexual pattern. Protogyny was confirmed in C. glaucofraenum. Sex change was either initiated or completed, typically by the largest female, in all-female groups held for 10 to 40 d. Ovarian, transitional, and testis structure were similar to that of C. nicholsi and C. personatus. No preformed testicular tissue was evident in the ovary proper and ovarian features were not retained in the sex-changed testis beyond the newly transformed stage. Secretory accessory gonadal structures associated with the testis and which develop at the time of sex change arose from precursive tissue masses associated with the ventral portion of the ovarian wall in the region of the common genital sinus. The rapid development and onset of function in these structures, generally preceding that of the associated developing testis, suggest that they may play an important role in sex change events and in advertising new male status. Based on observed similarities of ovarian, transitional and secondary testis structure in three protogynous Coryphopterus species, including one species isolated since the last closing of the American landbridge, it is probable that protogyny is an ancestral condition in this genus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00367632
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Chloroplast division polarity, a marker of cell division planes during morphogenesis inBangia vermicularis Harvey (Rhodophyceae) (1992)
    Springer
    Protoplasma 169 (1992), S. 155-167 
    Details
    ISSN: 1615-6102
    Keywords: Cell division ; Cytoplasmic channel ; Morphogenesis ; Plastokinesis ; Polarity ; Septum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Ultrastructural observations of dividing cells inBangia vermicularis revealed a type of chloroplast division (plastokinesis) not previously reported in the red algae. The polarity of this prekaryokinetic process serves as a reliable marker of the plane of cytokinesis, a key factor in establishing thallus morphology. At the onset of division one or more invaginations develop in the envelope of the large, lobed chloroplast and proceed centripetally through the stroma in the plane of the thylakoids, forming narrow cytoplasmic channels (CCs). The thylakoids are realigned somewhat, but are not constricted as the chloroplast is divided into two or more units. The number of resulting chloroplasts and the orientation of the CCs are dependent on cell type. Distinctive cylindrical cells at the base of the filamentous region, immediately distal to the holdfast, are shorter than broad and contain a central nucleus surrounded by a doughnutshaped chloroplast. The cylindrical morphology of the thallus is established early in the first periclinal division as multiple plastokinesis commences, generating several radially-arranged daughter chloroplasts. Cleavage of the original chloroplast is completed during subsequent cell divisions in the initial developmental stage, finally resulting in eight chloroplasts that are distributed to an equal number of wedge-shaped radial cells. Cells distal to the actively dividing basal cells are cuboidal and have a peripheral nucleus. Division of the single chloroplast prior to karyokinesis in these cells results in two or four daughter chloroplasts according to cell type. During or following plastokinesis, multilamellar bodies derived from the CE appear to serve as the source of membranes for the developing septum in the channels. Septa link to proliferations of the plasmalemma in areas of slight cell wall (CW) indentations, and are completed between daughter nuclei after karyokinesis, producing a cleavage channel. Subsequently, primary CW material is deposited between the two septal membranes. The shape and arrangement of daughter cells in each of the developmental stages in the thallus are defined by the planes of cell division. These are indicated by both the orientation of CCs and the polar orientation of nuclear division which is always at right angles to the CC.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01323615
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Ultrastructural changes in major organelles during spermatial differentiation inBangia (Rhodophyta) (1980)
    Springer
    Protoplasma 102 (1980), S. 253-279 
    Details
    ISSN: 1615-6102
    Keywords: Bangia ; Differentiation ; Organelles ; Rhodophyta ; Spermatiogenesis ; Ultrastructural transformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The major organelles within the cells of maleBangia atropurpurea (Roth) C. Ag. filaments undergo a series of ultrastructural transformations during the production of spermatia. Initially, thylakoids within the large axial chloroplast develop a reticulate pattern commencing at the central pyrenoid region. Subsequent changes involve loss of lobes and diminution of volume through division; chloroplasts in final stages contain a few dilated, distorted thylakoids and many plastoglobuli. During differentiation the large nucleolus disappears from the nucleus and four masses of chromatin aggregate near the nuclear envelope. Furrows originating from the nuclear envelope form double membranes around each of the chromatin masses and most of the nucleoplasm is eliminated. Several types of fibrillar vesicles are formed during the process and large floridean starch reserves are utilized. Multilamellar bodies and microbody-like structures occur within the cells during certain phases of spermatiogenesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01279591
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    7. Tundra stream macroalgae of North America: composition, distribution and physiological adaptations (1996)
    Springer
    Hydrobiologia 336 (1996), S. 67-82 
    Details
    ISSN: 1573-5117
    Keywords: arctic ; Chlorophyta ; cyanobacteria ; North America ; stream macroalgae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Eighty-three infrageneric taxa of stream macroalgae have been reported from tundra regions of North America, composed of 32 cyanobacteria, 35 Chlorophyta, 10 Chrysophyta and 6 Rhodophyta. There are few if any endemics represented in this flora. The most widespread species are the cyanobacteria Rivularia minutula, Nostoc commune and Tolypothrix tenuis as well as asexual populations of the chlorophyte genus Zygnema. The relative contribution of cyanobacteria compared to that of the Chlorophyta increases from the low to high arctic. Number of species per segment ranges from 0 to 7, with a mean of 2.8, and varies little between the low and high arctic. The percentage of stream bottom covered by macroalgae ranges from 0 to ca. 75%; mean cover values for low and high arctic streams are ca. 12 and 8%, respectively. Tundra macroalgae tend to be more abundant and diverse in less rigorously flowing stream sections. Most species tolerate prolonged freezing by forming resistant vegetative cells with thick walls, plentiful reserves and low molecular weight solutes to lower the freezing point. Many tundra stream macroalgae also produce ‘sunscreen’ pigments to reduce exposure to damaging radiation in the blue and ultraviolet regions. Nutrients tend to be low and phosphorus is often limiting in these systems. Arctic streams appear to differ from those of Antarctica in having potential grazers of macroalgae, such as the chironomid Diamesa, the mayfly Baetis and the caddisfly Brachycentrus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00010820
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Developmental studies on cultured endolithic conchocelis (Rhodophyta) (1984)
    Springer
    Hydrobiologia 116-117 (1984), S. 201-208 
    Details
    ISSN: 1573-5117
    Keywords: seaweed ; conchocelis ; endolith ; Rhodophyta ; culture ; development ; taxonomy ; morphology ; influence of substrate mineralogy ; morphometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00027666
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Distribution of stream macroalgae in south-central Alaska (1986)
    Springer
    Hydrobiologia 135 (1986), S. 259-269 
    Details
    ISSN: 1573-5117
    Keywords: Alaska ; streams ; lotic ; macroalgae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Forty stream segments were sampled throughout the Cook Inlet drainage basin in June 1984. There was a great range in stream size, current velocity, temperature, shading, conductance and water color. This range in variables presumably has resulted in a diverse flora of 40 species of lotic macroalgae. The major divisions in terms of species numbers were the Chlorophyta (43%), Bacillariophyta (25%), Rhodophyta (13%) and Xanthophyta (13%). Filaments were the predominant form (60% of species), though mats were common (28% of species). Species numbers and abundance were significantly correlated to water temperature. Distribution was patchy in the basin, with total cover varying from less than 1% to 90% of the stream bottom. Lowland brown-water streams flowing through emergent wetlands tended to have the highest species diversity and abundance. In the drainage basin, the chrysophyte Hydrurus foetidus and the blue-green alga Phormidium retzii exhibited strongly developed dominance. This pattern of niche pre-emption appears to be typical of stream macroalgal communities in general.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00006538
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    An evaluation of species relationships in the Porphyra perforata complex (Bangiales, Rhodophyta) using starch gel electrophoresis (1990)
    Springer
    Hydrobiologia 204-205 (1990), S. 179-183 
    Details
    ISSN: 1573-5117
    Keywords: electrophoresis ; Porphyra ; seaweed ; systematics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Traditional morphological features have formed the basis for distinguishing species of Porphyra. Among these features are number of cell layers, number of chloroplasts per cell, arrangement of reproductive structures on the thallus, and overall morphology. Chromosome number and chromosome morphology have helped corroborate some species identities. A survey of northeast Pacific species of Porphyra using starch gel electrophoresis of 15 soluble proteins has shown that electrophoretic banding patterns provide a reliable diagnostic tool for species identification. Data from starch gel electrophoresis are presented to confirm the identities of species formerly associated with the Porphyra perforata species-complex in British Columbia and northern Washington. Porphyra abbottae, P. fallax, P. kanakaensis, and P. torta are recognized as distinct species, and Porphyra sanjuanensis is synonymized with P. perforata.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00040231
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    The systematics of Porphyra: character evolution in closely related species (1993)
    Springer
    Hydrobiologia 260-261 (1993), S. 151-157 
    Details
    ISSN: 1573-5117
    Keywords: biogeography ; chromosomes ; habitat ; isozymes ; morphology ; phenology ; Porphyra ; systematics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Isozymes, vegetative and reproductive morphology, seasonality, vertical and geographic distributions and chromosomes were compared for six pairs of putative sibling species of Porphyra (P. abbottae/P. torta, P. fallax subsp. fallax/P. fallax subsp. conwayae, P. amplissima/P. cuneiformis, P. fucicola/P. ‘leucostica’, P. miniata/P. variegata, P. ‘umbilicalis’/P. ‘umbilicalis’) and among five species in a complex (P. brumalis, P. kurogii, P. ‘linearis’, P. pseudolinearis, and P. ‘purpurea’.) Geographic distribution and zymograms for certain proteins showed the greatest change between species pairs: only one pair of species had identical distributions, and most species pairs were disjunct; every species had a different allozyme for GOT-1, whereas all species had apparently identical proteins for phycoerythrin. Seasonality and habitat exhibited moderate differentiation: Northeast Pacific sibling species were characterized by a high intertidal winter species pairing with a mid intertidal spring species, whereas all but one of the other species pairs exhibited nearly identical vertical distributions and seasonalities. There were few changes in morphology: most species pairs had essentially identical morphologies and coloration and the same arrangement of reproductive cells. Chromosome numbers and karyotypes were identical for species pairs and in the species complex. These results provide evidence for different rates of evolution of different characters in the genus Porphyra.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00049014
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...