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  • gene expression  (69)
  • evolution  (60)
  • Springer  (128)
  • 2005-2009
  • 1995-1999  (128)
  • 1997  (128)
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  • 2005-2009
  • 1995-1999  (128)
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  • 1
    Electronic Resource
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    Springer
    Entomologia experimentalis et applicata 82 (1997), S. 37-44 
    ISSN: 1570-7458
    Keywords: Barbarea vulgaris ; Cruciferae ; Phyllotreta nemorum ; Chrysomelidae ; Alticinae ; flea beetle ; plant defence ; genetics ; sex-linkage ; X- and Y-chromosome ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A polymorphism in host plant exploitation has been discovered in the flea beetle, Phyllotreta nemorum L. (Coleoptera: Chrysomelidae: Alticinae) where one resistant population is able to use Barbarea vulgaris R.Br. ssp. arcuata (Opiz.) Simkovics (Brassicaceae) as a host plant while a susceptible population is not. Crosses (F1, F2, and backcrosses) between the two flea beetle populations were made, and survival of the progeny on B. v. ssp. arcuata was measured. The ability of P. nemorum larvae to survive in this plant species depended on the presence of major, dominant genes (R-genes). The two most abundant R-genes in the resistant flea beetle population were X- and Y-linked, respectively. The use of B. v. ssp. arcuata as a natural host plant by the resistant population of P. nemorum seems to be an extension of the host plant range of the species. The role of sex-linked genes in the evolution of host range is discussed.
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  • 2
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    Entomologia experimentalis et applicata 82 (1997), S. 25-35 
    ISSN: 1570-7458
    Keywords: Barbarea vulgaris ; Cruciferae ; Phyllotreta nemorum ; Chrysomelidae ; Alticinae ; flea beetle ; plant defence ; resistance ; host plant ; variation ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Several sorts of variation in the interaction between the insect, Phyllotreta nemorum L. (Coleoptera:Chrysomelidae:Alticinae), and the plant, Barbarea vulgaris R.Br. (Brassicaceae), have been discovered: 1) genetic differences in the levels of defences in the plant, 2) genetic differences in the ability of insects to cope with the plant defences, 3) seasonal variation in levels of defences in the plant, and 4) differences between leaf types in levels of defences. Two plant accessions were suitable for larval development throughout the season while the remaining nine accessions were more or less unsuitable for larvae from the ‘susceptible’ T-population at least at certain times of the year. All accessions were suitable for the ‘resistant’ E-population throughout the year. There was a seasonal variation in levels of defences in some accessions which were unsuitable for the T-population during the summer period when beetles were present, but not during autumn and spring when the beetle were hibernating. Upper (younger) cauline leaves of these accessions had higher levels of defences than lower (older) cauline leaves. The resistant E-population used B. vulgaris as a natural host plant while the susceptible T-population did not. The use of B. vulgaris as a natural host plant by the E-population of P. nemorum seems to be an extension of the host plant range of the species. Variation in plant defences may have facilitated the switch in host plant use by the resistant flea beetle population.
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  • 3
    ISSN: 1573-0417
    Keywords: colonization ; evolution ; lakes ; Norway ; deglaciation ; land uplift ; invertebrates ; Chironomidae ; Porifera ; Bryozoa ; diatoms ; Charophyta ; tsunami
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Invertebrate colonization of lakes following the uplift of land from the sea was studied in four lakes, currently situated between 39 and 24 m a.s.l., on the central Norwegian coast. The lakes were isolated from the sea between 9500 and 7700 years B.P. Animal and algal remains picked from core samples showed that the first colonizers preserved as fossils were usually members of the Chironomidae, Daphnidae/Chydoridae, Acarina, Porifera (Ephydatia mülleri and Spongilla lacustris), Bryozoa (Cristatella mucedo and Plumatella spp.) and Charophyta (Chara sp.). Of the chironomids, the genus Chironomus was present in the oldest lacustrine layers of all four lakes, but other genera recorded at the marine/lacustrine boundary were Dicrotendipes, Procladius (?), Einfeldia, Microtendipes, and Glyptotendipes. Remains of the caddis fly family Limnephilidae were also present in the earliest lacustrine sediments in Kvennavatnet and Kvernavatnet. The oldest invertebrate fauna is typical for mesotrophic lakes. However, chironomids and mites have been present in this area from at least about 10 500 years B.P. A diverse chironomid community was established between 300 and 800 years after isolation from the sea at Kvernavatnet on the island of Hitra, while only between 80 and 120 years passed before a comparably diverse community developed at Kvennavatnet on the mainland coast. A similar development of the invertebrate fauna occurred in Kvennavatnet, Kvernavatnet and Storkuvatnet. However, Litjvatnet deviates greatly from the ‘normal’ pattern because a tsunami disturbed the bottom sediments and fauna. The tsunami, a gigantic sea wave, was caused by a submarine slide from the Norwegian continental slope. It reached Litjvatnet, today located 24 m a.s.l., but was not traced in Storkuvatnet at 30 m a.s.l. This event happened about 7200 years B.P.
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  • 4
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    Antonie van Leeuwenhoek 71 (1997), S. 159-178 
    ISSN: 1572-9699
    Keywords: aromatic pathways ; chlorobenzenes ; evolution ; genes ; plasmids ; pseudomonas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chlorobenzenes are substrates not easily metabolized by existing bacteria in the environment. Specific strains, however, have been isolated from polluted environments or in laboratory selection procedures that use chlorobenzenes as their sole carbon and energy source. Genetic analysis indicated that these bacteria have acquired a novel combination of previously existing genes. One of these gene clusters contains the genes for an aromatic ring dioxy-genase and a dihydrodiol dehydrogenase. The other contains the genes for a chlorocatechol oxidative pathway. Comparison of such gene clusters with those from other aromatics degrading bacteria reveals that this process of recombining or assembly of existing genetic material must have occurred in many of them. Similarities of gene functions between pathways suggest that incorporation of existing genetic material has been the most important mechanism of expanding a metabolic pathway. Only in a few cases a horizontal expansion, that is acqui sition of gene functions to accomodate a wider range of substrates which are then all transformed in one central pathway, is observed on the genetic level. Evidence is presented indicating that the assembly process may trigger a faster divergence of nearby gene sequences. Further ‘fine-tuning’, for example by developing a proper regulation, is then the next step in the adaptation.
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  • 5
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    Antonie van Leeuwenhoek 71 (1997), S. 265-270 
    ISSN: 1572-9699
    Keywords: bacteria ; DNA ; evolution ; genome ; RNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This review examines evolution of bacterial genomes with an emphasis on RNA based life, the transition to functional DNA and small evolving genomes (possibly plasmids) that led to larger, functional bacterial genomes.
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  • 6
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    Antonie van Leeuwenhoek 71 (1997), S. 257-263 
    ISSN: 1572-9699
    Keywords: bacteria ; energy ; evolution ; genome ; metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This article examines the relationship between (or dependence of) bacterial evolution in prokaryotes and metabolism, and the changing physical-chemical conditions present during early evolution.
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  • 7
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    Antonie van Leeuwenhoek 71 (1997), S. 363-368 
    ISSN: 1572-9699
    Keywords: assembly ; anode ; bacteria ; cathode ; DNA ; evolution ; genetics ; molecular ; surfaces
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Molecular evolution is examined in bacteria with an emphasis on mineral surfaces, membranes, cathodes and anodes. In early molecular evolution, cathode-anode system may have been naturally occurring on a nm to µm scale. Secondly, the cathode-anode system could have been separated by a primitive, permeable lipid or microsphere on a mineral surface, that was a precursor of a more advanced membrane with a charge differential on either side of the membrane. These aspects will be considered from a theoretical evolutionary perspective.
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  • 8
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    Antonie van Leeuwenhoek 72 (1997), S. 251-259 
    ISSN: 1572-9699
    Keywords: bacteria ; catalysis ; DNA ; enzyme ; evolution ; microorganisms ; optimization ; RNA ; time
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Microbial populations (and life) not only evolve, they optimize. The transition from a random, unorganized, lifeless Earth to the present situation, where the Earth is virtually covered with nucleic acids and diverse and complex species, required numerous molecular changes and the integration of metabolic pathways over billions of years. Primitive prokaryotic life was dependent on and constrained by the physical-chemical conditions on the Earth, while slowly reshaping conditions present. In this review, molecular evolution and molecular optimization are examined with an emphasis on the order in which evolutionary events occurred.
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  • 9
    ISSN: 1573-4919
    Keywords: calreticulin ; gene expression ; steroid receptor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Calreticulin is a ubiquitously expressed Ca2+ binding protein of the endoplasmic reticulum which inhibits DNA binding and transcriptional activation by steroid hormone receptors. In this study the effects of calreticulin on tyrosine aminotransferase (TAT) gene expression in cultured McA–RH7777 hepatocytes was investigated. McA–RH7777 cells were stably transfected with calreticulin expression vector to generate cells overexpressing the protein. The transcriptional activity of the TAT gene, which is glucocorticoid–sensitive and cAMP–dependent, was investigated in the mock transfected McA–RH7777 and in cells overexpressing calreticulin (designated McA–11 and McA–17). In the presence of dexamethasone or the cAMP analog (CTP–cAMP) expression of the TAT gene was induced in mock transfected McA–RH7777 cells by approximately 4.5 and 5 fold, respectively. In McA–11 and McA–17 cells, overexpressing calreticulin, glucocorticoi ever, the CTP–cAMP–dependent expression of the TAT gene was not affected. The ability of calreticulin to inhibit glucocorticoid–sensitive TAT gene expression but not the cAMP–dependent expression of the gene suggests that the protein affects specifically the action of transcription pathways involving steroid receptors or transcription factors containing KxFF(K/R)R–like motifs. Calreticulin may play an important role in the regulation of glucocorticoid–sensitive pathway of expression of the hepatocytes specific genes during development.
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  • 10
    ISSN: 1573-4919
    Keywords: regucalcin ; calcium-binding protein ; gene expression ; diabetic state ; ethanol ; liver injury
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The alteration in calcium-binding protein regucalcin in the liver and serum of rats with streptozotocin (STZ)-diabetic state or ethanol ingestion was investigated. STZ (6.0 mg/100 g body weight) was subcutaneously administered in rats, and 1 or 3 weeks later they were sacrificed by bleeding. Liver regucalcin mRNA levels were not clearly altered by the diabetic state, as evidenced by Northern blotting using regucalcin cDNA (0.9 kb of open reading frame). Based on enzyme-linked immunoadsorbent assay (ELISA) with rabbit-anti-regucalcin IgG, hepatic regucalcin concentration was decreased about 50% of control levels by STZ treatment. However, serum regucalcin concentration was not significantly altered by STZ treatment. Meanwhile, when rats ingested ethanol (10 and 30%) in the drinking water for 2 weeks, liver regucalcin mRNA levels were clearly increased, although hepatic regucalcin concentration was significantly decreased. Serum regucalcin concentration was not appreciably altered. Serum transaminases (GOT and GPT) activities were significantly increased at 1 or 3 weeks after STZ administration in rats, while their activities were not altered by ethanol ingestion. The present study demonstrates that hepatic regucalcin concentration is decreased independent of mRNA expression in the STZ-diabetes and during ethanol ingestion in rats.
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  • 11
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    Molecular and cellular biochemistry 167 (1997), S. 169-177 
    ISSN: 1573-4919
    Keywords: tamoxifen ; interferon ; gene expression ; breast cancer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The molecular basis for the enhanced growth inhibition of MCF-7 human breast cancer xenografts by a combination of human interferon-β (IFN-β) and tamoxifen was investigated. Treatment of MCF-7, MDA-MB-231, and BT-20 cells with the combination of IFN-β and tamoxifen resulted in enhanced antiproliferative effects in vitro. Treatment with the combination of IFN-β and tamoxifen enhanced the expression of several IFN-β-inducible genes in human breast carcinoma cell lines relative to levels induced by IFN-β alone. Tamoxifen alone did not induce transcription of IFN-stimulated genes (ISGs). Augmentation of ISG expression by the combination of IFN-β and tamoxifen was noted in breast tumor cell lines irrespective of their functional estrogen receptor (ER) status or their dependence on estradiol for growth, suggesting that upregulation of ISGs was independent of ER status. Enhancement of IFN-stimulated gene expression by tamoxifen occurred at the transcripti onal level. Expression of transfected reporter genes under the control of IFN-α/β regulated promoters was also enhanced in IFN-β and tamoxifen-treated cells. Similarly, transcriptional induction of chimeric reporter plasmids driven by an IFN-γ inducible promoter (GAS; IFN-γ activated site) was also enhanced by the combination of IFN-γ and tamoxifen. In tamoxifen treated cells, IFN-β and IFN-γ readily activated transcription factors ISGF-3 and GAF, respectively. Therefore, augmentation of ISG expression by tamoxifen is an early event in the antitumoral activity of this drug combination. (Mol Cell Biochem 167: 169-177, 1997)
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  • 12
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    Molecular and cellular biochemistry 172 (1997), S. 47-57 
    ISSN: 1573-4919
    Keywords: smooth muscle ; gene transfer ; DNA ; RNA ; ribozyme ; liposome ; lipoxygenase ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Chemically synthesized hammerhead-type ribozymes targeted against the porcine leukocyte-type 12-lipoxygenase (LO) have been developed and studied. One chimeric ribozyme consists of DNA in the non-enzymatic portions, and RNA in the enzymatic core as well as two phosphorothioate internucleotide linkages at 3′ terminus. The second ribozyme consists of ribonucleotide sequences generated by in vitro transcription. In this chapter we describe methodologies to first analyze the ribozyme catalytic activity in vitro by studying cleavage of target RNA in vitro. The subsequent sections will describe how to target the catalytic ribozyme and deliver it to porcine vascular smooth muscle cells (PVSMC) by a liposome-mediated method. Finally ways to evaluate its activity to inhibit expression of the 12-LO mRNA will be presented. These results demonstrate the feasibility of using ribozymes as novel candidates for therapeutic agents to block specific gene expression in vascular cells.
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  • 13
    ISSN: 1573-4919
    Keywords: heart ; DNA ; library ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The availability of high quality cDNA libraries is often crucial to the successful identification and characterization of genes. The concepts and potential pitfalls of constructing cDNA libraries are presented. Various applications requiring high quality cDNA libraries are outlined, including large-scale single pass sequencing of cDNA clones to generate expressed sequence tags (ESTs) and differential screening of cDNA libraries. The usefulness of combining such approaches for the discovery of novel disease-related and cardiovascular-based ESTs (CVBest) is discussed.
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  • 14
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    Molecular and cellular biochemistry 173 (1997), S. 59-69 
    ISSN: 1573-4919
    Keywords: hydrogen peroxide ; oxidative stress ; gene expression ; lens epithelial cells ; N-acetylcysteine ; pyrrolidine dithiocarbamate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The involvement of H2O2 in cataract development has been established inboth human patients and animal models. At the molecular level H2O2 has beenobserved to cause damage to DNA, protein and lipid. To explore the oxidativestress response of the lens system at the gene expression level, we haveexamined the effects of H2O2 on the mRNA change of the proto-oncogenes,c-jun, c-fos and c-myc in a rabbit lens cell line, N/N1003A. H2O2 treatmentof the rabbit lens epithelial cells for 60 min induces quick up-regulationof both c-jun and c-fos mRNAs. The maximal induction is 38 fold for c-jun at150 µM and 72 fold for c-fos at 250 µM H2O2. Treatment ofN/N1003A cells with 50-250 µM H2O2 for 60 min leads to a 2-5 foldincrease of the c-myc mRNA level. H2O2 also induces an up-regulation intransactivity of the activating protein-1 (AP-1) as shown with a reportergene driven by a prolactin gene promoter with 4 copies of AP-1 binding sitesinserted in the upstream of the promoter. Maximal induction occurs with 150µM H2O2. In the same system, the antioxidants, N-acetyl-cysteine (NAC)and pyrrolidine dithiocarbamate (PDTC) at concentrations shown toup-regulate the mRNAs of both c-jun and c-fos, also enhance thetransactivity of AP-1. NAC and PDTC have different effects in modulating theinduction of AP-1 activity by H2O2 and TPA. These results reveal thatoxidative stress regulates expression of various regulatory genes in lenssystems, which likely affects cell proliferation, differentiation andviability and thus affect normal lens functions.
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  • 15
    ISSN: 1573-4919
    Keywords: regucalcin ; calcium-binding protein ; cDNA cloning ; gene expression ; mouse liver
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The molecular cloning of the cDNA coding for a Ca2+-binding proteinregucalcin and its mRNA expression in mouse liver were investigated. ThecDNA clone encoding a regucalcin was isolated from a mouse liver cDNAlibrary and sequenced. Analysis of the sequence of the cloned cDNA showedthat the cDNA encoded the complete amino acid sequence of the mouseregucalcin molecule; the cDNA had an open reading frame of 897 bp. Mouseregucalcin was composed of 299 amino acid residues, and its molecular weightwas estimated to be 33,406 Da. The amino acid sequence of mouse regucalcinhad 94% homology, as compared with that of rat regucalcin. Northernblot analysis with the mouse liver cDNA probe revealed that mouse regucalcinmRNA was mainly present in the liver but only slightly in the kidney with asize of 1.8 kb. Hepatic regucalcin mRNA level of male mouse was higher thanthat of female mouse. A single intraperitoneal administration of calciumchloride (5, 15, and 30 mg Ca2+/100 g body weight) to mice induced aremarkable increase in regucalcin mRNA in the liver; the increase inregucalcin mRNA levels at 30 min after calcium administration wasdose-dependent. The present results demonstrate that regucalcin mRNA in miceis uniquely expressed in the liver, and that its expression is stimulated bycalcium administration.
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  • 16
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    Molecular and cellular biochemistry 176 (1997), S. 273-279 
    ISSN: 1573-4919
    Keywords: cardiac hypertrophy ; myosin heavy chain ; gene expression ; adrenergic system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Growth of the heart in hypertrophy is accompanied by changes in the phenotypic expression of cardiac genes. To explore the molecular basis of cardiac hypertrophy, we have analyzed the regulation of myosin heavy chain gene (MHC) expression. In one set of experiments, pressure overload on the rat heart was produced by constriction of the abdominal aorta. Changes in the α and β-MHC mRNA were then studied in overloaded hearts and following load removal. Pressure overload resulted in down-regulation of the α-MHC with corresponding up-regulation of the steady state level of β-MHC mRNA. Load removal (debanding) resulted in regression of cardiac hypertrophy and a rapid return of α-MHC mRNA to normal values. In contrast, the recovery in β-MHC mRNA was much slower to the extent that it remained substantially elevated compared to respective sham controls even after 7 weeks of post-debanding. These results suggest that putative load-related signals independently regulate two genes. Several lines of evidence indicate that adrenergic nervous system plays an important role in the induction and maintenance of cardiac hypertrophy and in the redistribution of myosin isoforms. We have analyzed the effect of cAMP inducing agents on the regulation of a-MHC gene in primary cultures of the fetal (18 day) rat cardiac myocyte. Inclusion of 8 Br-cAMP in the culture media increased the expression of α-MHC promoter/reporter construct comprising of 2.9 kb upstream sequence of the α-MHC gene. Several deletion mutations in the α- MHC gene promoter defined the cAMP responsive boundaries to be a 32 bp region comprising of -71 to -40 bp sequences. Deletion of this region resulted in loss of cAMP response as well as in basal expression of α-MHC promoter/reporter construct. These data suggest a role of β-adrenergic pathway in the modulation of α-MHC gene expression.
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  • 17
    ISSN: 1573-4927
    Keywords: glycophorins ; gorilla ; evolution ; gene family ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Homologues of MN blood group antigens, encoded by members of the glycophorin A (GPA) gene family, are expressed in man, anthropoid apes, and some species of Old World monkeys. Previous studies had shown that a three-gene framework, most closely related to that in man, is present in the chimpanzee. Here we report the genomic structure, transcript map, and protein expression of the GYPA locus in gorillas. Compared to the corresponding human and chimpanzee homologues, gorilla GPA, GPB, and GPB/E genes each showed a high degree of sequence identity, with the same exon-intron organization. However, the expression of exons III, IV, or V encoding the extracellular or membrane domains of homologous glycophorins varied among the three species. Gorilla GPA and GPB/E genes were unique in that the former occurred in two allelic forms with or without the expression of exon III, whereas the latter contained one (ψ exon III) instead of two silenced exons (ψ exons III and IV). Differences from human but not chimpanzee GPA also included the presence of a hybrid M/N epitope and the absence of the sequon for N-glycosylation. Owing to the retention of a functional exon III, gorilla GPB was more similar to chimpanzee GPB than human GPB. A transspecies allele was identified in the gorilla that gave rise to the Henshaw (He)-like antigen similar to that found in man. These results provide further insight into the model for evolution of the GPA gene family, indicating that the mechanisms underlying inter- and intraspecific polymorphism of glycophorins could predate the divergence of gorillas as the consequence of gene duplication and diversification.
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  • 18
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    Molecular and cellular biochemistry 172 (1997), S. 37-46 
    ISSN: 1573-4919
    Keywords: gene transfer ; gene expression ; adenovirus ; blood vessel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Adenovirus-mediated gene transfer is a promising method for studies of vascular biology and potentially for gene therapy. Intravascular approaches for gene transfer to blood vessels in vivo generally require interruption of blood flow and have several limitations. We have used two alternative approaches for gene transfer to blood vessels in vivo using perivascular application of vectors. First, replication-deficient adenovirus expressing nuclear-targeted bacterial b-galactosidase was injected into cerebrospinal fluid via the cisterna magna of rats. Leptomeningeal cells over the major arteries were efficiently transfected, and adventitial cells of large vessels and smooth muscle cells of small vessels were occasionally stained. When viral suspension was injected with the rat in a lateral position, the reporter gene was expressed extensively on the ipsilateral surface of the brain. Thus, adenovirus injected into cerebrospinal fluid provides gene transfer in vivo to cerebral blood vessels and, with greater efficiency, to perivascular tissue. Furthermore, positioning of the head may ‘target’ specific regions of the brain. Second, vascular gene delivery was accomplished by perivascular injection of virus in peripheral vessels. Injection of the adenoviral vector within the periarterial sheath of monkeys resulted in gene transfer to the vessel wall that was substantial in magnitude although limited to cells in the adventitia. Approximately20% of adventitial cells expressed the transgene, with no gene transfer to cells in the intima or media. These approaches may provide alternative approaches for gene transfer to blood vessels, and may be useful for studies of vascular biology and perhaps vascular gene therapy.
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  • 19
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    Molecular and cellular biochemistry 172 (1997), S. 111-120 
    ISSN: 1573-4919
    Keywords: differential display ; cardiac development ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract An estimated 15,000 different mRNA species are expressed in a typical mammalian cell. The differential expression of mRNAs in both a temporal and cell-specific manner determines the fate of the cell and creates the organism. Analysis of this differential gene expression has become a central aim of many laboratories attempting to understand the mechanisms underlying various biological processes. Currently, we are using a technique called differential display to analyze the differential expression of genes in cardiomyocytes. Differential display is a rapid and powerful technique that was introduced by Liang and Pardee in 1992. Since that time, it has been successfully applied by several groups, and it is quickly becoming a standard method for studying differential gene expression. Here, we present a detailed article discussing the differential display methodology and how we have utilized it to identify potential genes involved in cardiomyocyte proliferation. Furthermore, we have provided a list of materials and supplied examples of data obtained, in an effort to allow the reader to perform the technique with success in their own laboratory.
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  • 20
    ISSN: 1573-4919
    Keywords: plasminogen activators ; plasminogen activator inhibitors ; gene expression ; left ventricular hypertrophy ; pressure overload
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract In the early stages of left ventricular hypertrophy (LVH) acute adaptive changes occur in the coronary vasculature as it remodels. Plasminogen activators (PAs) and inhibitors (PAIs) have the potential effects of proteolytic degradation that is relevant to tissue remodeling and angiogenesis. Our study focused on the possible roles of PAI-1, PAI-2, uPA and tPA in myocyte hypertrophy and angiogenesis in the early and late stages of pressure overload induced left ventricular hypertrophy (LVH). We divided seventeen adult swine, weighing 24.2 ± 6.5 kg, into four groups: control, sham-operated, early LVH and late heart failure LVH group. At surgery we placed a fixed constrictor on the ascending aorta immediately above the aortic valve. This increased LV systolic pressure from 133 ± 15 to 193 ± 24 mm Hg after the surgery. We subdivided the early group into groups of 3 animals each that we euthanized at 8, 24 and 72 h after operation and obtained heart samples for analysis. In the late heart failure group individual animals were euthanized at 55, 59, 62 and 72 days after the detection of congestive heart failure. We also obtained tissue samples from the control and sham-operated swine. Sections for histologic analysis were fixed in 10% buffered formalin. We isolated RNA, size fractionated it using 1% formaldehyde-agarose gel electrophoresis and then did Northern blots. The mRNAs from both PAI-1 and PAI-2 showed a remarkable increase at 8 and 24 h after acute aortic constriction and returned to control by 72 h. Regional differences showed that most of the increases were in the endocardium. Three animals in the late heart failure LVH group were determined to be in congestive heart failure at about 2 months after the onset of aortic constriction. In these animals PAI-1 and PAI-2 were increased in both the left and right ventricles but remained low in an animal of the same elevation in aortic pressure seen by the LV who did not have congestive failure. These data suggest that PA and PAI gene expressions change before morphologic changes occur in the early stages of developing LVH. Also at the time of onset of congestive heart failure this increased expression reappears. PAs and PA inhibitors mRNA levels vary in the different regions of the heart reflecting changing wall stresses. Thus, the PAs and PA inhibitors may play an important role in angiogenesis that occurs during the early stages of LVH. The increased expression in the late stage of LVH may reflect further changes in wall stresses since these animals also showed overt clinical signs of heart failure.
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  • 21
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    Journal of chemical ecology 23 (1997), S. 1527-1547 
    ISSN: 1573-1561
    Keywords: Secondary metabolites ; chemical defense ; evolution ; ascidians ; sponges
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract We used three chemical fractions (spanning a wide range of polarities) from the extracts of four marine invertebrates, the spongesCrambe crambe andHemimycale columella and the ascidiansCystodytes dellechiajei andPolysyncraton lacazei, to test inhibition of cell division, photosynthesis, and settlement. We used assay organisms from the same habitat, seeking to determine whether a species may display diverse, ecologically relevant bioac-tivities and, if so, whether the same types of compound may be responsible for such activities. Cell division was strongly inhibited by the spongeC. crambe. A dichloromethane fraction fromC. crambe prevented development of sea urchinParacentrotus lividus eggs at a concentration of 10 μg/ml, as did the butanolic fraction, but at higher concentrations (50 and 100 μg/ml). At 50 μg/ml, the aqueous fraction ofC. crambe allowed cell division but prevented eggs from developing beyond the gastrula stage. Similar results were recorded with the dichloromethane fraction ofP. lacazei and from the aqueous fraction ofH. columella. Photosynthesis was unaffected by any of the species at 50 μg/ml. Larval settlement was inhibited by one or another fraction from the four species surveyed at a concentration of 50 μg/ml, althoughC. crambe exhibited the greatest amount of activity. We therefore found that various fractions displayed the same type of bioactivity, while compounds from the same fraction were responsible for multiple activities, suggesting that secondary metabolites are multiple-purpose tools in nature, which is relevant to our understanding of species ecology and evolution. Moreover, results showed that the assessment of the role of chemical compounds is significantly influenced by the assay organism, fractionation procedure, concentration, and duration of experiments. All these factors should be carefully considered when testing ecological hypotheses of the roles of chemically-mediated bioactivities.
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  • 22
    ISSN: 1573-4919
    Keywords: estrogen ; apolipoprotein ; gene expression ; mice ; atherosclerosis
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    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Estrogen protects against developing premature coronary artery disease.However, the mechanism of protective effects of estrogen still remainspoorly understood. One mechanism by which estrogen can have protectiveeffects apppears to be through modulation of plasma lipoproteins. We showedthat the mouse can be used as animal model to study estrogen-mediatedsynthesis and secretion of lipoproteins since, unlike the rat, the mousedoes not up-regulate LDL receptors (Srivastava et al. [4]). Since inbredstrains of mice differ in their genetic background and show differingresponsiveness to dietary lipids, we examined how various inbred strains ofmice respond to estradiol administration, and whether some mouse strainsshow responses similar to rats. 17b-estradiol was administered to male micefrom 15 different inbred strains, and the changes in plasma levels oflipids, apoB, apoAI, and apoE were examined. Total cholesterol decreased inall but one strain, apoAI levels decreased in all but 3 strains while apoBlevels and apoB/apoAI ratios increased in all but 2 strains, suggesting thatin contrast to rats, the apoB-containing lipoproteins increased relative toHDL in all strains of mice examined. Basal and estradiol-induced changes intotal cholesterol were significantly correlated with changes in apoAI, butnot apoB, reflecting the predominance of HDL over other lipoproteins inmouse plasma. The effects of estrogen on plasma apoE levels varied amongvarious inbred strains of mice tested. Plasma apoE levels increased in sevenstrains treated with estrogen, and remained unchanged in the rest. Toexamine whether changes of plasma apoproteins are associated with thechanges in the respective hepatic mRNA levels, apoAI, B and E mRNA werequantified by RNase protection assay. Hepatic apoE mRNA did not showcorrelation with either basal or post treatment plasma apoE levels in any ofthe strains. Similarly, most of the mouse strains did not show correlationof plasma apoAI and apoB levels with the corresponding hepatic mRNA levels.These results suggest that estrogen regulates plasma lipoproteinconcentrations primarily by posttranscriptional mechansims, and there werestrain-related differences in the estrogen-mediated regulation oflipoprotein metabolism.
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  • 23
    ISSN: 1573-4919
    Keywords: regucalcin ; Ca2+-binding protein ; insulin ; gene expression ; HepG2 cells ; transformed cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The expression of hepatic Ca2+-binding protein regucalcin in the cloned human hepatoma cells (HepG2) was investigated. The change in regucalcin mRNA levels was analyzed by Northern blotting using rat liver regucalcin complementary DNA (0.9 kb of open reading frame). Regucalcin mRNA was expressed in HepG2 cells, although the mRNA was markedly expressed in normal rat liver. Moreover, regucalcin protein in HepG2 cells was detected by Western blot analysis using a polyclonal rabbit anti-regucalcin antibody. Regucalcin mRNA expression in HepG2 cells was clearly stimulated by the culture with insulin (10-8 M) of the effective concentration. Regucalcin protein in HepG2 cells was also increased by the treatment of insulin (10-8 M). The present results demonstrate that regucalcin is expressed in the transformed HepG2 cells, and that the expression is stimulated by insulin.
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  • 24
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    Molecular and cellular biochemistry 177 (1997), S. 1-6 
    ISSN: 1573-4919
    Keywords: gene expression ; mRNA secondary structure ; single tube RT-PCR ; TNF receptor I
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    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The secondary structure of human tumor necrosis factor receptor I (TNFR-I) mRNA based on its lowest folding energy was predicted. Three combinations of primers selected from open-regions and four combinations of primers from closed-regions of TNFR-I mRNA structure were employed for single-tube reverse transcription-polymerase chain reaction (RT-PCR) for the determination of TNFR-I gene expression in U937 cell. All the primers were designed with the same criteria. However, the different primers generated distinct quantities of RT-PCR products from the same concentration of TNFR-I mRNA, implying that the determination of gene expression by RT-PCR was affected by the mRNA secondary structure. In addition, the sensitivity of the open-region RT-PCR was approximately one hundred-fold higher than that in the closed-regions of TNFR-I mRNA. The low efficiency of the closed-region RT-PCR was not correlated with the G/C content of the TNFR-I mRNA structure. These results suggest that consideration of the influence of intrinsic mRNA structure of a gene is essential prior to the determination of gene expression by quantitative RT-PCR, and this open-region strategy of primer design may yield an efficient primer for in vitro amplification of cDNA by RT-PCR.
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  • 25
    ISSN: 1573-4919
    Keywords: cholesteryl ester ; CETP ; Caco-2 ; polymerase chain reaction ; gene expression ; mRNA ; alternative splicing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Cholesteryl ester transfer protein (CETP) is a plasma protein involved in the reverse cholesterol transport and expressed in several human tissues and cell lines. We studied CETP expression in Caco-2 cell line, a model of the human enterocyte epithelium. By reverse-transcriptase polymerase chain reaction, we could demonstrate that in basal condition Caco-2 cells have a low rate of expression of active CETP mRNA. Furthermore, we found that even in this cell line CETP mRNA alternative splicing occurs with deletion of exon 9 sequence. Densitometric analysis of the in vitro amplified fragments showed that under basal conditions about 60% of reverse transcribed CETP cDNA corresponds to exon 9-deleted transcripts. After challenge with 50 µM sodium oleate, there is a ∼2 fold increase in the transcription rate of the full-length CETP cDNA, as measured by competitive PCR, which is accompanied to an increased activity measured in the cell-conditioned medium. On the contrary, no significant change is seen in the amount of exon 9-deleted cDNA. Consequently, an inversion in the ratio of full-length and exon 9-deleted CETP cDNA is evident, suggesting that sodium oleate selectively enhances the expression of full-length CETP mRNA.
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  • 26
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    Molecular biology reports 24 (1997), S. 221-230 
    ISSN: 1573-4978
    Keywords: gene expression ; ribonucleoprotein ; RNase MRP ; RNase P ; transcription
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We report on the expression of mouse RNase MRP RNA in human embryonic kidney 293 cells upon DNA transfection. Stable cell lines were selected by cotransfection with a neo r gene. Transcription of wild-type and deletion mutants of MRP RNA and ribonucleoprotein formation were assessed by RNase protection and immunoprecipitation experiments. Mouse MRP RNA as expressed in 293 cells readily associates with human proteins to form a chimeric Th ribonucleoprotein. 5' truncated MRP RNAs, however, failed to associate with Th antigen(s) and deletion of the 3' sequences of MRP RNA greatly reduced the expression in stable as well as in transient transfectants. Abbreviations: nt(s) – nucleotide(s); RNP – ribonucleoprotein.
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  • 27
    ISSN: 1573-5028
    Keywords: cDNA cloning ; ethylene ; fruit ripening ; gene expression ; melon ; wounding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In vitro translation of mRNAs and polyacrylamide gel electrophoresis of proteins from melons revealed that several mRNAs increased in amount during ripening, indicating the existence of other ripening genes in addition to those cloned previously. To identify ripening-related genes we have screened a ripe melon cDNA library and isolated two novel cDNA clones (MEL2 and MEL7) encoding unidentified proteins. Southern analysis revealed that MEL2 and MEL7 are encoded by low-copy-number genes. The MEL2 cDNA clone is near full-length, corresponds to a 1600 nucleotide mRNA that accumulates during ripening and encodes a predicted protein rich in hydrophobic amino acids. The MEL7 cDNA clone is full-length, corresponds to a mRNA of 0.7 kb which accumulates during early ripening stages and is also present at low levels in other organs of the melon plant. The MEL7 predicted polypeptide is 17 kDa and shows significant homology with the major latex protein from opium-poppy. Wounding and ethylene treatment of unripe melon fruits 20 days after anthesis showed that MEL2 and MEL7 mRNAs are only induced by ethylene.
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  • 28
    ISSN: 1573-5028
    Keywords: gene expression ; heat shock ; oxidative stress ; ozone ; pathogenesis-related protein ; Petroselinum crispum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Parsley (Petroselinum crispum L.) is known to respond to pathogen attack by the synthesis of furanocoumarins and to UV irradiation by the synthesis of flavone glycosides whereas ozone treatment results in the induction of both pathways. A cDNA library from parsley plants was differentially screened using labelled reverse-transcribed poly(A)+ RNA isolated from ozone-treated parsley plants. This resulted in the isolation of 13 independent cDNA clones representing ozone-induced genes and of 11 cDNA clones representing ozone-repressed genes. DNA sequencing of several clones resulted in the identification of pathogenesis-related protein 1-3 (PR1-3), of a new member of PR1 cDNAs (PR1-4) and of a small heat shock protein (sHSP). Northern blot analyses showed a transient induction of the three mRNA species after ozone fumigation. In contrast, heat shock treatment of parsley plants resulted in an increase of sHSP mRNA whereas no increase for transcripts of PR1-3 and PR1-4 could be observed. This is the first characterized sHSP cDNA clone for plants induced by heat shock, as well as by oxidative stress caused by ozone.
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  • 29
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    Plant molecular biology 33 (1997), S. 301-311 
    ISSN: 1573-5028
    Keywords: asparagine ; asparagine synthetase ; cDNA clone ; complementation ; gene expression ; Glycine max
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two cDNA clones (SAS1 and SAS2) encoding different isoforms of asparagine synthetase (AS; EC 6.3.5.4) were isolated. Their DNA sequences were determined and compared. The amino-terminal residues of the predicted SAS1 and SAS2 proteins were identical to those of the glutamine binding domain of AS from pea, asparagus, Arabidopsis and human, suggesting that SAS1 and SAS2 cDNAs encode the glutamine-dependent form of AS. The open reading frames of SAS1 and SAS2 encode a protein of 579 and 581 amino acids with predicted molecular weights of 65 182 and 65 608 Da respectively. Similarity of the deduced amino acid sequences of SAS1 and SAS2 with other known AS sequences were 92% and 93% for pea AS1; 91% and 96% for pea AS2; 88% and 91% for asparagus; 88% and 90.5% for Arabidopsis; 70.5% and 72.5% for E. coli asnB and 61% and 63% for man. A plasmid, pSAS2E, was constructed to express the soybean AS protein in Escherichia coli. Complementation experiments revealed that the soybean AS protein was functional in E. coli. Southern blot analysis indicated that the soybean AS is part of a small gene family. AS transcript was expressed in all tissues examined, but higher levels were seen in stem and root of light-grown tissue and leaves of dark-treated tissue.
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  • 30
    ISSN: 1573-5028
    Keywords: in vivo protein synthesis ; gene expression ; germination ; isocitrate lyase ; isoform ; megagametophyte ; Pinus taeda L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two full-length cDNAs encoding the glyoxysomal enzyme isocitrate lyase(ICL) were isolated from a λZAP cDNA library prepared frommegagametophyte mRNAs extracted from seeds imbibed at 30 °C for 8days. The cDNAs, designated Ptbs ICL 8 and Ptbs ICL 12, have openreading frames of 1740 and 1719 bp, with deduced amino acid sequences of580 and 573 residues, respectively. The predicted amino acid sequencesof Ptbs ICL 8 and Ptbs ICL 12 exhibit a 79% identity with each other,and have a greater than 75% identity with ICLs from variousangiosperm species. The C-termini of Ptbs ICL 8 and Ptbs ICL 12terminate with the tripeptide Ser-Arg-Met and Ala-Arg-Met, respectively,both being conserved variants of the type 1 peroxisomal targetingsignal. RNA blot and slot analysis revealed that Ptbs ICL 8 and PtbsICL 12 mRNAs were present at low levels in the megagametophyte of themature and stratified seeds, and that the level of both transcriptsincreased markedly upon seed germination. Protein blot analysisindicated that the steady-state level of ICL was low in the mature andstratified seed, then increased rapidly upon seed germination, peakingat around 8-10 days after imbibition (DAI). Changes in the level ofICL activity in cell-free extracts was similar to the steady-stateprotein content with the exception that ICL activity was not detected inmegagametophyte extracts of mature or stratified seeds. From 10-12 DAIwhen the megagametophyte tissue senesced, ICL activity decreased rapidlyto near undetectable levels. In contrast, steady-state levels of ICLprotein and mRNA remained relatively constant during megagametophytesenescence. In vivo synthesis of ICL protein was measured to shedlight on these differences. ICL immunoselected from[35S]-methionine labelled proteins indicated that ICL wassynthesized at very low levels during megagametophyte senescence.Together, the results show that loblolly pine ICL gene expression iscomplex. While temporal regulation appears to be primarilytranscriptional, it also involves a number of post-transcriptionalprocesses including at least one translational and/or post-translationalmechanism.
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  • 31
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    Plant molecular biology 34 (1997), S. 345-352 
    ISSN: 1573-5028
    Keywords: heat shock ; pea (Pisum sativum L.) ; gene expression ; pod lignification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A pea pod cDNA library was screened for sequences specific to lignifying tissue. A cDNA clone (pLP19) encoding the C-terminal region of a hsp70 heat shock protein hybridised only to pod mRNA from pea lines where pod lignification occurred. Expression of pLP19 was induced by heat shock in leaves, stems and roots of pea and chickpea plants. Four different poly(A) addition sites were observed in cDNAs derived from the same gene as pLP19. This gene was fully sequenced; unlike most hsp70 genes, it contains no introns. The 5′-flanking sequence contains heat shock elements and other potential regulatory sequences.
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  • 32
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    Plant molecular biology 33 (1997), S. 821-834 
    ISSN: 1573-5028
    Keywords: leaf senescence ; genes ; gene expression ; subtractive hybridisation ; Brassica napus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A subtractive hybridisation technique was developed to clone cDNAs representing genes that showed enhanced expression during leaf senescence in Brassica napus. A number of different genes were identified that, when analysed by northern hybridisation, showed different patterns of expression during leaf development but were all expressed at increased levels during senescence. Sequence analysis of these cDNAs showed that several types of genes were found including two different proteases, glutamine synthetase, ATP sulphurylase, catalase, metallothionein, ferritin and an antifungal protein. The possible roles of these gene products in the senescence process are discussed.
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  • 33
    ISSN: 1573-5028
    Keywords: gene expression ; grass ; Phalaris ; self-incompatibility ; thioredoxin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Self-incompatibility is widespread in the grasses and it is proposed that the grasses share a common incompatibility mechanism that is distinct from those operating in the dicotyledonous species studied in great detail. Where good genetic data are available, all grass species appear to have an incompatibility mechanism controlled by two unlinked loci, S and Z. A putative S gene has been cloned from Phalaris coerulescens. This gene is characterized by two major domains: an allele specificity domain and a thioredoxin catalytic domain. A family of sequences with varying degrees of homology to this gene has been identified among 15 grass species covering all subfamilies of the Poaceae. These S-related sequences appear to be present in the grass family regardless of self-compatibility. Evidence is presented to show that at least one of the sequences is transcribed, suggesting a functional gene. In contrast to the high expression of the S gene in Phalaris pollen, expression of the related gene in the pollen (or anthers) of the grass species examined was so low that RNA gel blot analysis failed to display a significant signal. However, reverse transcription-based polymerase chain reaction (RT-PCR) successfully amplified the region corresponding to the S thioredoxin domain from 10 of the grass species. With grasses other than Phalaris, RT-PCR showed limited success in amplifying the region corresponding to the S variable portion at the 5′ end of the Phalaris S gene. Sequencing of the PCR-amplified S thioredoxin region from wheat, barley, rye and Dactylis revealed that this is a highly conserved gene with 94–97% sequence similarity with the corresponding Phalaris S gene. The conservation of sequence and ubiquitous expression of the gene across the grass family strongly suggest that the S-related gene is carrying out a significant biological function in the Poaceae. On the basis of these findings, a model for the evolution of the S self-incompatibility gene in the grasses is proposed.
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  • 34
    ISSN: 1573-5028
    Keywords: chloroplast-derived trnH ; chloroplast genome ; DNA transfer ; gene expression ; Gramineae ; mitochondrial genome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We reported previously that the mitochondrial sequence that contains the chloroplast-derived trnH gene has been highly conserved in the region around one terminus of the junction between chloroplast-derived and mitochondrion-specific sequences in most of the gramineous plants analyzed [15]. The results of RT-PCR, northern hybridization, in vitro capping and ribonuclease protection experiments show that the chloroplast-derived trnH gene is transcribed from a putative promoter that is located in the mitochondrion-specific sequence. Gene expression in this region seems to be correlated with the conservation of the sequence at the junction between the chloroplast-derived fragment and the mitochondrion-specific sequence.
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  • 35
    ISSN: 1573-5028
    Keywords: Bacillus thuringiensis ; coleoptera ; eggplant ; gene expression ; insect resistance ; Solanum integrifolium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Solanum melongena (eggplant) cv. Picentia and the wild species Solanum integrifolium were transformed with both a wild type (wt) and four mutagenized versions of Bacillus thuringiensis (Bt) gene Bt43 belonging to the cry3 class. The Bt gene was partly modified in its nucleotide sequence by replacing four target regions (W: +1 to +170; X: +592 to+1057 ; Y: +1203 to +1376; Z: +1376 to +1984) with synthetic fragments obtained by polymerase chain reaction amplification of crude oligonucleotides. The synthetic Bt genes were designed to avoid, in their modified regions, sequences such as ATTTA sequence, polyadenylation sequences and splicing sites, which might destabilize the messenger RNA. Furthermore, the codon usage was improved for a better expression in the plant system. The amino acid composition was not altered. Four versions of the modified Bt gene were obtained, BtE, BtF, BtH and BtI, with a nucleotide subtitution percentage of 8.2, 8.6, 14, and 16%, respectively, in comparison to the wt gene Bt43. Modified versions contained different subsets of substituted regions: BtE - W+Z, BtF - Y+Z, BtH - X+Y+Z, BtI - W+X+Y+Z. In the final modified version (BtI), overall guanine + cytosine was increased from the 34.1% of the wt gene to 45.5%, and most of the destabilizing sequences were eliminated. Transgenic plants obtained with the more modified versions, BtH and BtI, were fully resistant to Leptinotarsa decemlineata Say first- and third- instar larvae, while Bt43 wt, BtE and BtF genotypes did not cause mortality and did not affect larval development.
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  • 36
    ISSN: 1573-5028
    Keywords: chlorophyll a-binding protein ; gene expression ; LHC ; light-harvesting complex ; photosystem I ; rhodophyte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The accessory light-harvesting polypeptides associated with photosystem I (LHCI) in Porphyridium cruentum bind chlorophyll a, zeaxanthin and β-carotene. A cDNA library of P. cruentum was screened with an antiserum specific to the LHCI polypeptides, and an 0.9 kb fragment was identified as coding for an LHCI polypeptide. This cDNA, which we named LhcaR1, has an open reading frame encoding 222 amino acid residues including a putative transit peptide of 28 amino acids. Hydropathy analysis suggests that there are three transmembrane helices in the mature polypeptide. Each of the amino acid residues that bind chlorophyll (six residues) and serve in stabilizing the helices in higher-plant LHCs are conserved in helices 1 and 3 of P. cruentum LhcaR1. The N-terminal flanking regions of these two helices also show high sequence conservation with other LHCs. Helix 2 contains a seventh putative chlorophyll-binding site, but resembles helix 2 of higher-plant LHCs to a lesser degree. A sequence motif of 11 residues found near the N-terminus and in each of the three helices suggests the possibility that the red algal LhcaR1 derives from a gene duplication. Polypeptides of the expected molecular weight in six other red algae (Achrochaetium, Bangia, Callithamnion, Cyanidium, Polysiphonia, Spermothamnion) were recognized by the antiserum to P. cruentum LHCI, indicating a wide distribution of LHCI in rhodophytes.
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  • 37
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    Plant molecular biology 33 (1997), S. 1-10 
    ISSN: 1573-5028
    Keywords: androgenesis ; anther and microspore culture ; gene expression ; haploids ; pollen embryogenesis
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  • 38
    ISSN: 1573-5028
    Keywords: 1-aminocylopropane-1-carboxylate ; ACC oxidase ; ACC synthase ; cold ; 1-methylcyclopropene ; propylene ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Passe-Crassane pears require a 3-month chilling treatment at 0 °C to be able to produce ethylene and ripen autonomously after subsequent rewarming. The chilling treatment strongly stimulated ACC oxidase activity, and to a lesser extent ACC synthase activity. At the same time, the levels of mRNAs hybridizing to ACC synthase and ACC oxidase probes increased dramatically. Fruit stored at 18 °C immediately after harvest did not exhibit any of these changes, while fruit that had been previously chilled exhibited a burst of ethylene production associated with high activity of ACC oxidase and ACC synthase upon rewarming. ACC oxidase mRNA strongly accumulated in rewarmed fruits, while ACC synthase mRNA level decreased. The chilling-induced accumulation of ACC synthase and ACC oxidase transcripts was strongly reduced when ethylene action was blocked during chilling with 1-methylcyclopropene (1-MCP). Upon rewarming ACC synthase and ACC oxidase transcripts rapidly disappeared in 1-MCP-treated fruits. A five-week treatment of non-chilled fruits with the ethylene analog propylene led to increased expression of ACC oxidase and to ripening. However, ethylene synthesis, ACC synthase activity and ACC synthase mRNAs remained at very low level. Our data indicate that ACC synthase gene expression is regulated by ethylene only during, or after chilling treatment, while ACC oxidase gene expression can be induced separately by either chilling or ethylene.
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  • 39
    ISSN: 1573-5028
    Keywords: proline ; Δ1-pyrroline-5-carboxylate synthetase ; osmotic stress ; gene expression ; salt tolerance ; rice (Oryza sativa L.)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cDNA for Δ1-pyrroline-5-carboxylate (P5C) synthetase (cOsP5CS), an enzyme involved in the biosynthesis of proline, was isolated and characterized from a cDNA library prepared from 14-day-old seedlings of Oryza sativa cv. Akibare. The deduced amino acid sequence of the P5CS protein (OsP5CS) from O. sativa exhibited 74.2% and 75.5% homology to that of the P5CS from Arabidopsis thaliana and Vigna aconitifolia, respectively. Northern blot analysis revealed that the gene for P5CS (OsP5CS) was induced by high salt, dehydration, treatment of ABA and cold treatment, while it was not induced by heat treatment. Simultaneously, accumulation of proline was observed as a result of high salt treatment in O. sativa. Moreover, the levels of expression of OsP5CS mRNA and content of proline under salt stress condition were compared between a salt-tolerant cultivar, Dee-gee-woo-gen (DGWG) and a salt-sensitive breeding line, IR28. It was observed that the expression of the P5CS gene and the accumulation of proline in DGWG steadily increased, whereas those in IR28 increased slightly.
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  • 40
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    Plant molecular biology 33 (1997), S. 467-481 
    ISSN: 1573-5028
    Keywords: Ca2+ ; cell signaling ; Chlamydomonas ; gene expression
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    Topics: Biology
    Notes: Abstract Acid shock of Chlamydomonas results in flagellar excision and induction of flagellar protein RNAs. The magnitude of flagellar RNA accumulations after flagellar excision by mechanical shear depends on the extracel]ular Ca2+ concentration. In this report, we demonstrate that the magnitude and duration of flagellar RNA accumulations are signaled by an acid shock-induced Ca2+ influx. RNA accumulations were greater in cells acid shocked in 500 µM CaCl2 than in 200 µM CaCl2, although the accumulation durations were similar. RNA accumulations of lower magnitude and shorter duration were observed in cells in Ca2+-containing buffer treated with CdCl2. RNA accumulations were of still lower magnitude and shorter duration in cells shocked in buffer without added CaCl2 than in cells shocked in 200 or 500 µM CaCl2 or in the presence of CdCl2. RNA accumulations similar to those in cells shocked in buffer without added CaCl2 were measured in cells following acid shock in buffer containing 200 µM CaCl2 and supplemented with neomycin, ruthenium red, or LaCl3. Acid shock of the adf-1 mutant resulted in RNA accumulations of shorter duration and lower magnitude than those measured in adf-1 cells stimulated by mechanical shear. These results are consistent with an hypothesis that acid shock generates two genetically and pharmacologically distinct signals governing flagellar RNA induction; the first signal is independent of a Ca2+ influx and flagellar excision and results in low magnitude accumulations of short duration, and the second is a consequence of a Ca2+ influx and results in accumulations of high magnitude and long duration.
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  • 41
    ISSN: 1573-5028
    Keywords: 1-aminocyclopropane-1-carboxylate (ACC) synthase ; elicitor ; ethylene ; gene expression ; tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The key enzyme of ethylene biosynthesis, ACC synthase, is encoded by a multigene family. We describe three new DNA sequences encoding members of the ACC synthase family of the tomato. One of these sequences encodes a novel ACC synthase, LE-ACS6, which is phylogenetically related to the ACC synthases LE-ACS1A and LE-ACS1B. Gene-specific probes for seven tomato ACC synthase genes were prepared. They were used for RNase protection assays to study the accumulation of ACC synthase transcripts in suspension-cultured tomato cells after the addition of an elicitor. The ACC synthase genes LE-ACS2, LE-ACS5 and LE-ACS6 were strongly induced by the elicitor. In contrast, the genes LE-ACS1B, LE-ACS3 and LE-ACS4 were constitutively expressed and LE-ACS1B was present at all times at a particularly high level. Thus, there are two groups of ACC synthase transcripts expressed in these cells, either elicitor-induced or constitutive. A transcript of LE-ACS1A was not detected. Despite the presence of LE-ACS1B, LE-ACS2, LE-ACS3, LE-ACS4 and LE-ACS5, there was only little ethylene produced in the absence of the elicitor. Increased ethylene production is usually correlated with the accumulation of ACC synthase transcripts, indicating that ethylene production is controlled via the transcriptional activation of ACC synthase genes. However, the abundance of several ACC synthase mRNAs studied was not strictly correlated with the rate of elicitor-induced ethylene production. Our data provide evidence that the activity of these ACC synthases may not solely be controlled by the transcriptional activation of ACC synthase genes.
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  • 42
    ISSN: 1573-5028
    Keywords: conglutin ; gene expression ; leginsulin ; Lupinus angustifolius ; basic 7S globulin ; transgenic plants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The expression of genes encoding conglutin γ and a leginsulin-like protein has been examined in narrow-leafed lupin, Lupinus angustifolius L. Conglutin γ is a homologue of basic 7S globulin (Bg), the insulin and leginsulin binding protein from soybean. Accumulation of conglutin γ mRNA, as assessed by northern assays and reverse-transcription PCR, was tightly regulated both spatially and temporally in lupin plants and was detected almost exclusively in developing seeds. Similar tissue and temporal specificity was demonstrated when 1.8 kb of the promoter region from the conglutin γ gene was used to drive the expression of a β-glucuronidase reporter gene in transgenic plants. In stably transformed tobacco the conglutin γ promoter produced strong, temporally regulated and seed-specific expression of the reporter gene which was localised to the embryo tissues and to a layer of cells adjacent to the seed coat. A truncated 0.29 kb promoter fragment produced much reduced levels of expression and a loss of embryo specificity. Leginsulin-like mRNA was similarly detected in lupins only in developing seeds. The leginsulin-like gene detected in L. angustifolius showed 96% sequence identity to leginsulin from soybean within the 280 bp region amplified from lupin by PCR. The results demonstrate that both components of a Bg-leginsulin putative signal transduction pathway are present in the seeds of lupin.
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  • 43
    ISSN: 1573-5028
    Keywords: auxin ; cell expansion ; cellulase ; endo-1,4-β-glucanase ; ethylene ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Plant developmental processes involving modifications to cell wall structure, such as cell expansion, organ abscission and fruit ripening, are accompanied by increased enzyme activity and mRNA abundance of endo-1,4-β-glucanases (EGases). An EGase cDNA clone, Ce14, isolated from tomato (Lycopersicon esculentum) has been shown to be identical to a tomato pistil-predominant EGase cDNA, TPP18. In addition to its previously reported expression during certain stages of early pistil development, Ce14 mRNA was also detected at high levels in the growing zones of etiolated hypocotyls (about 2.5-fold less than in pistils) and in young expanding leaves (about 3.5-fold less than in pistils). The abundance of Ce14 mRNA declined precipitously in older tissues as cells became fully expanded, and was barely detectable in mature vegetative tissues. Ce14 mRNA abundance was also low in abscission zones, and did not increase as abscission progressed. In fruit, Ce14 mRNA was present at low levels during fruit expansion, but was essentially absent during subsequent fruit development and ripening. Treatment of etiolated hypocotyls with ethylene or high concentrations of auxin sufficient to induce rapid lateral cell expansion and hypocotyl swelling also brought about an approximate doubling of Ce14 mRNA abundance, suggesting that Ce14 mRNA accumulation may be promoted directly or indirectly by ethylene. Thus, accumulation of Ce14 mRNA was found to be correlated with rapid cell expansion in pistils, hypocotyls and leaves.
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  • 44
    ISSN: 1573-5028
    Keywords: gene expression ; gene family ; higher plant ; phosphorylation ; post-transcriptional regulation ; Solanum tuberosum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A polymerase chain reaction product (PKIN503) was amplified from potato (Solanum tuberosum) cv. Désirée using oligonucleotide primers with sequences which are highly conserved in the plant sucrose non-fermenting 1 (SNF1)-related protein kinase gene family. Southern blot analysis showed the presence of 5–10 SNF1-related genes in the potato genome. PKIN503 was used to screen a tuber cDNA library and a genomic library, and one cDNA and five genomic clones were isolated. The nucleotide sequences of a portion of all five genomic clones were shown to be identical and only one, pgPKIN1, was analysed further. The cDNA was found to be truncated at the 5′ end but the cDNA and genomic sequences contained only 15 substitutions, two of which resulted in changes in the derived amino acid sequence. PKIN1 was shown to encode an Mr 57854 protein with 61–70% sequence similarity with other plant SNF1-related protein kinases. Northern blot analysis revealed some tissue-specific differences in PKIN1 transcript levels, the lowest being detected in leaves and the highest in stolons. However, much greater differences were found in SNF1-related activity, which was measured using a phosphorylation assay with a substrate peptide which has been shown previously to be phosphorylated by plant SNF1-related protein kinases. Activity decreased by almost 80% during development from stolons to mature tubers but it increased about seven-fold during the first seven days of storage after harvesting, before decreasing again. However, activity was highest in mini-tubers, where the levels were 37 times greater than those in mature tubers from a pot-grown plant. Transcript levels in these tissues were approximately equal, clear evidence that SNF1-related protein kinase activity in potato is regulated, in part, post-transcriptionally.
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  • 45
    ISSN: 1573-5028
    Keywords: gene expression ; gibberellin biosynthesis ; gibberellin 20-oxidases ; Phaseolus vulgaris ; Pisum sativum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract PCR was used with degenerate primers based on conserved amino acid sequences in gibberellin (GA) 20-oxidases to isolate cDNA clones for these enzymes from young seeds of pea (Pisum sativum) and developing embryos of French bean (Phaseolus vulgaris). One GA 20-oxidase cDNA (Ps27-12) was obtained from pea and three (Pv15-11, Pv73-1 and Pv85-26) from bean. Their identities were confirmed by demonstrating that fusion proteins expressed in Escherichia coli exhibited GA 20-oxidase activity, converting [14C]GA12 to [14C]GA9. The intermediates in this three-step reaction, GA15 and GA12, were also identified as products. The expression proteins from three of the clones (Ps27-12, Pv15-11 and Pv73-1) were also shown to convert GA53 to GA20, as effectively as they did GA12. On the basis of transcript levels measured by northern blot analysis, the pea GA 20-oxidase gene is most highly expressed in young leaves, fully expanded internodes, very young seeds (until 4 days after anthesis) and expanding pods (from 3 days after anthesis at least until day 6). Expression in pods from 3-day-old unpollinated ovaries is higher than in those from pollinated ovaries. Treatment of unpollinated ovaries with GA3 to induce parthenocarpic fruit-set severely reduced the amount of GA 20-oxidase mRNA, whereas treatment with 2,4-D, although inducing fruit-set, did not reduce the levels of these transcripts. Plant decapitation above an unpollinated ovary resulted in very high levels of GA 20-oxidase mRNA in the pod. The three GA 20-oxidase genes from French bean showed very different patterns of expression: Pv15-11 was expressed in the roots, young leaves, and developing seeds, but most highly in immature cotyledons, while Pv73-1 has a similar expression pattern to Ps27-12, with transcripts found only in young seeds and young leaves, where it was particularly abundant. Transcripts corresponding to Pv85-26 were detected in developing seeds, and just traces in the young leaves. Southern blot analysis indicated that the bean GA 20-oxidases are each encoded by single-copy genes, whereas one more gene, homologous to Ps27-12, could also exist in pea.
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  • 46
    ISSN: 1573-5028
    Keywords: cDNA cloning ; environmental factors ; gene expression ; leaf senescence ; organs ; tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Senescence-related cDNA clones designated SENU1, 4, 5 (senescence up-regulated) and SEND32, 33, 34, 35 and 36 (senescence down-regulated) isolated from a tomato leaf cDNA library [9] were characterized. Southern analysis showed that SEND32 is encoded by a single-copy gene while SEND33, 34, 35, 36 and SENU1 and SENU5 are members of small gene families. DNA and protein database searches revealed that SEND32, SEND35, SENU1 and SENU5 are novel cDNAs of unknown function. SEND33 encodes ferredoxin, SEND34 encodes a photosystem II 10 kDa polypeptide and SEND36 encodes catalase. The SENU4 sequence is identical to the P6 tomato protein previously reported to be pathogenesis-related [46]. The mRNA levels of SENU1, 4 and 5 increased during leaf senescence and SENU1 and SENU5 were also expressed at high levels during leaf development and in other plant organs. The SENU4 mRNA was associated more specifically with leaf senescence, although low expression was also detected in green fruit. The mRNAs for all SEND clones decreased during tomato leaf development and senescence and all except SEND32 were expressed at low levels in other plant organs. The accumulation of mRNA homologous to SENU4 and the decrease in abundance of SEND32 provide good molecular markers for leaf senescence.
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  • 47
    ISSN: 1573-5028
    Keywords: S-adenosylmethionine decarboxylase ; carnation ; cDNA sequence ; gene expression ; protein processing ; uORF
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract S-adenosylmethionine decarboxylase (SAMDC; EC 4.1.4.50) is one of the key enzymes in polyamine biosynthesis, and the product of its catalytic reaction, decarboxylated S-adenosylmethionine (dcSAM), serves as an aminopropyl donor in the biosynthesis of spermidine and spermine. In order to provide information on the structure and regulation of SAMDC, we have isolated and sequenced two different SAMDC cDNA clones from carnation petals. The nucleotide sequences of CSDC9 and CSDC16 show 78.3% identity, and the deduced amino acid sequences show 81.7% identity and 86.5% similarity [12]. There are several regions with highly conserved sequences among SAMDC cDNAs of potato, spinach, periwinkle, man and yeast. These conserved regions include a cleavage site for the processing of SAMDC proenzyme and a putative PEST sequence that may be relevant to the rapid degradation of SAMDC protein. Carnation SAMDC cDNAs have long transcript leaders of 472 bp and 502 bp for CSDC9 and CSDC16, respectively. Both sequences contain short upstream open reading frames (uORFs) in their 5′ -untranslated regions. The CSDC9 uORF is 54 amino acids from 152 to 317 while the corresponding sequence in CSDC16 is 52 amino acids located from 156 to 314 in each 5′-untranslated region. The nucleotide sequences of uORFs in CSDC9 and CSDC16 were 89.9% identical. In vitro transcription/translation experiments showed: (1) each proenzyme of both cDNAs of SAMDC was converted to two polypeptides consisting of a large subunit (calculated as 31544 Da and 32537 Da, respectively) and a small subunit (calculated as 9704 and 9041 Da, respectively) after 20 min of translation; (2) the processing occurs rapidly during the translation of protein. But once the translation process is stopped accumulation of the subunits slows and never reaches completion even after 300 min. The processing of carnation SAMDC enzyme is not stimulated by putrescine in in vitro transcription/translation reaction.
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  • 48
    ISSN: 1573-5028
    Keywords: arginine decarboxylase ; gene expression ; Oryza sativa ; polyamines ; rice ; salinity stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of salinity stress on the activity of arginine decarboxylase (ADC, EC 4.1.1.19), the first enzyme in biosynthesis of polyamines (PA) from arginine, as well as its transcript level has been compared in salt-sensitive (M-1-48) and salt-tolerant (Pokkali) rice cultivars. Treatment of 72 h grown seedlings either with increasing concentrations of NaCl or with 150 mM NaCl for different time periods, showed a gradual increase of activity in Pokkali. In M-1-48 an immediate increase followed by sharp decrease was observed on prolonged treatment beyond 6 h or above 150 mM NaCl. To generate a DNA probe for ADC, the polymerase chain reaction was used with oat genomic DNA and sequence-specific primers. A region of oat genomic DNA containing a coding sequence for 166 amino acids of the C-terminal part of the ADC enzyme was amplified and called OAD1. Southern analysis of EcoRI- or BamHI-cut genomic DNAs from different cultivars of rice with OAD1 as the probe revealed strong hybridization with one DNA fragment of rice and restriction fragment length polymorphism (RFLP) was noticed. Northern analysis of total RNA of rice with OAD1 as the probe revealed hybridization with a transcript of similar size to the ADC transcript in oat. While in Pokkali, at least a 20-fold accumulation of OAD1 homologous transcript was detected after treatment with 200 mM NaCl, only a seven-fold increase in transcript level was found in M-1-48 after 150 mM NaCl treatment. Results suggest that in the salt-tolerant rice cultivar Pokkali, ADC enzyme activity increases and its transcript also accumulates during the prolonged salinity stress, this mechanism is absent in the salt-sensitive rice cultivar M-1-48 where a prolonged period of salinity stress down-regulates both ADC activity and its transcript level.
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  • 49
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    Plant molecular biology 34 (1997), S. 643-650 
    ISSN: 1573-5028
    Keywords: callus ; crown tissue ; gene expression ; low temperature ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The low-temperature (2 °C)-specific wheat cDNA, pTACR7, represents a gene designated tacr7 from hard red winter wheat (HRWW; Triticum aestivum L. cv. Winoka). The term low-temperature-specific (LTS) is used because tacr7 is not induced by ABA or stresses such as salt, dehydration, and heat. pTACR7 was isolated by RT-PCR with mRNA from wheat crown tissue, the oligonucleotide primers derived from the barley cognate pHVCR8 (GenBank accession number L28091). Based on the deduced amino acid sequence, TACR7 is highly hydrophobic, with a single transmembrane domain and an amino acid bias for leucine (19%). Thus, the encoded protein TACR7 is unique among low-temperature-regulated wheat proteins described in the literature. Analysis of steady-state levels of tacr7 transcripts (630 nt) showed accumulation in wheat seedlings, crown tissue, and callus cultures after transfer from control (25 °C) to low temperature (2 °C). No detectable transcripts were observed by northern blot hybridization with pTACR7 probe from seedling or callus treated with ABA, salt, dehydration, or heat stress. tacr7 transcripts accumulated during 2 °C exposure to a greater amount in a freeze-resistant HRWW (FR; SDmut 16029) than in a freeze-susceptible HRWW (FS; SDmut 16169) crown tissue, with the largest difference between genotypes being 30% ± 3% at 3 weeks.
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  • 50
    ISSN: 1573-9368
    Keywords: peanut ; engineered virusresistance ; tomato spotted wiltvirus ; transformation ; nucleocapsid ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The nucleocapsid gene of tomato spotted wilt virus Hawaiian L isolate in a sense orientation, and the GUS and NPTII marker genes, were introduced into peanut (Arachis hypogaea cv. New Mexico Valencia A) using Agrobacterium-mediated transformation. Modifications to a previously defined transformation protocol reduced the time required for production of transformed peanut plants. Transgenes were stably integrated into the peanut genome and transmitted to progeny. RNA expression and production of nucleocapsid protein in transgenic peanut were observed. Progeny of transgenic peanut plants expressing the nucleocapsid gene showed a 10- to 15-day delay in symptom development after mechanical inoculations with the donor isolate of tomato spotted wilt virus. All transgenic plants were protected from systemic tomato spotted wilt virus infection. Inoculated non-transformed control plants and plants transformed with a gene cassette not containing the nucleocapsid gene became systemically infected and displayed typical tomato spotted wilt virus symptoms. These results demonstrate that protection against tomato spotted wilt virus can be achieved in transgenic peanut plants by expression of the sense RNA of the tomato spotted wilt virus nucleocapsid gene
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  • 51
    ISSN: 1573-9368
    Keywords: superoxide dismutase ; recombinant protein ; transgeneexpression ; metalloprotein ; gene expression ; transgenic rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Expression of human extracellular superoxide dismutase (EC-SOD), a glycosylated, tetrameric metalloprotein, was targeted to the lactating mammary gland of transgenic rabbits. Efficient expression of the recombinant whey acidic protein/ec-sod gene was achieved and up to 3 mg ml−1 of the enzyme was secreted into the milk. Rabbit milk-produced recombinant EC-SOD was primarily found in the whey and purified by a two-step chromatographic method. To evaluate the rabbit milk-produced human EC-SOD, comparisons with native and Chinese hamster ovary cell (CHO)-produced EC-SOD were performed. All proteins were tetrameric and N-glycosylated. The behaviour on SDS-PAGE and size-exclusion chromatography indicated that the masses, and thereby the extent of post-translational modification of the proteins was similar. The monosaccharide composition of both recombinant EC-SOD variants was analysed and indicated similarities in the attached N-glycans on the two proteins. Furthermore, the peptide maps of the three EC-SOD variants revealed that all proteins had similar polypeptide backbones
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  • 52
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    Plant systematics and evolution 206 (1997), S. 33-45 
    ISSN: 1615-6110
    Keywords: Compositae ; Barnadesioideae ; Doniophyton ; Chuquiraga ; Argentina ; Chile ; evolution ; systematics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This revision describes, illustrates and documents morphological variation inDoniophyton (Compositae, Barnadesioideae), restricted to Argentina and Chile. Two species are recognized,D. anomalum andD. weddellii (sp. nova), possessing distinct morphological and chromosomal features, elevational tolerances, and nearly allopatric distributions.Doniophyton weddellii occurs primarily in central to northern Andean Chile and Argentina from 1900–4000 m a. s. l.;D. anomalum is found principally in centralwestern Argentina and south into Patagonia at 0–1800 m a. s. l. Close relationship exists withChuquiraga of subfam.Barnadesioideae. It is hypothesized thatDoniophyton evolved out ofChuquiraga in the high central Andes between Chile and Argentina. It is suggested thatD. weddellii differentiated first, correlating with an aneuploid chromosomal decrease from n = 27 (inChuquiraga) to n = 25. Further evolution and chromosomal decrease to n = 24 resulted inD. anomalum, with accompanying migration into southern Andes and Patagonia. Nomenclatural changes result from examination of protologues and type specimens:Doniophyton anomalum replaces the commonly used nameD. patagonicum, and a new species,D. weddellii, is described for the taxon masquerading under the routinely used superfluous nameD. andicola.
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  • 53
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    Biology and philosophy 12 (1997), S. 207-224 
    ISSN: 1572-8404
    Keywords: evolution ; epistemology ; evolutionary epistemology ; naturalized epistemology ; thought experiments ; modality ; utility ; fitness ; adaptation ; reliability ; possible worlds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Philosophy
    Notes: Abstract Roy Sorensen advances an evolutionary explanation of our capacity for thought experiments which doubles as a naturalized epistemological justification. I argue Sorensen”s explanation fails to satisfy key elements of environmental-selectionist explanations and so fails to carry epistemic force. I then argue that even if Sorensen succeeds in showing the adaptive utility of our capacity, he still fails to establish its reliability and hence epistemic utility. I conclude Sorensen”s account comes to little more than a “just-so story”.
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  • 54
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    Biology and philosophy 12 (1997), S. 385-397 
    ISSN: 1572-8404
    Keywords: morality ; evolution ; error theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Philosophy
    Notes: Abstract Michael Ruse‘s Darwinian metaethics has come under just criticism from Peter Woolcock (1993). But with modification it remains defensible. Ruse (1986) holds that people ordinarily have a false belief that there are objective moral obligations. He argues that the evolutionary story should be taken as an error theory, i.e., as a theory which explains the belief that there are obligations as arising from non-rational causes, rather than from inference or evidential reasons. Woolcock quite rightly objects that this position entails moral nihilism. However, I argue here that people generally have justified true beliefs about which acts promote their most coherent set of moral values, and hence, by definition, about which acts are right. What the evolutionary story explains is the existence of these values, but it is not an error theory for moral beliefs. Ordinary beliefs correspond to real moral properties, though these are not objective or absolute properties independent of anyone‘s subjective states. On its best footing, therefore, a Darwinian metaethics of the type Ruse offers is not an error theory and does not entail moral nihilism.
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  • 55
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    Evolutionary ecology 11 (1997), S. 301-335 
    ISSN: 1573-8477
    Keywords: ecological associations ; evolution ; integrative biology ; Opisthobranchia ; resource tracking ; Sacoglossa ; Ulvophyceae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Evolution in the opisthobranch order Sacoglossa has been closely linked to their specialized suctorial herbivorous habits. All shelled Sacoglossa (about 20% of the species) feed on one algal genus, Caulerpa. The non-shelled Sacoglossa have 'radiated' to other diets, mainly siphonalean or septate green algae (Class Ulvophyceae). Comparing the phylogeny of sacoglossan genera with the phylogeny of the Ulvophyceae indicates that co-speciation may have taken place at the basal node of the Sacoglossa, and that host switching has taken place several times in the two non-shelled clades. It is suggested that the most important evolutionary process has been speciation by 'resource-tracking'; the resource tracked is most probably cell wall composition of the algal prey. The fossil record of extant sacoglossan genera dates back to the Eocene and, based on the fossil record of siphonalean green algae, the Sacoglossa most likely appeared in the Cretaceous. It is hypothesized that the ancestral sacoglossan was epifaunal, suctorial and herbivorous, and the 'ancestral' food plant was not Caulerpa, but filamentous, calcified, now extinct, Udoteaceae.
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  • 56
    ISSN: 1573-8477
    Keywords: dispersal ; evolution ; evolutionarily stable strategy ; migrant ; resident ; survival
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We investigate how age-structure and differences in certain demographic traits between residents and immigrants of a single species act to determine the evolutionarily stable dispersal strategy in a two-patch environment that is heterogeneous in space but constant in time. These two factors have been neglected in previous models of the evolution of dispersal, which generally consider organisms with very simple life-cycles and assume that, whatever their origin, individuals in a given habitat have the same bio-demographic characteristics. However, there is increasing empirical evidence that dispersing individuals have different demographic properties from phylopatric ones. We develop a matrix model in which recruitment depends on local population densities. We assume that dispersal entails a proportional cost to immigrant fecundity, which can be compensated by differences in survival rates between immigrants and residents. The evolutionarily stable strategies (ESS) for dispersal are identified using a combination of analytical expressions and numerical simulations. Our results show that philopatry is selected (1) when dispersal rates do not vary in space, (2) when the metapopulation is a source-sink system and (3) when dispersal rates vary in space (asymmetric dispersal) and immigrants do not compensate for their reduced fecundity. We observe that non-zero asymmetric dispersal rates may be evolutionarily stable when (1) immigrants and residents are demographically alike and (2) immigrants compensate totally for their reduced fecundity through an increase in adult survival. Under these conditions, we find that the ESS occurs when the fitnesses at equilibrium in the two habitats, measured in our model by the realized reproductive rates, are each equal to unity. A comparison with previous studies suggests a unifying rule for the evolution of dispersal: the dispersal rates which permit the spatial homogenization of fitnesses are ESSs. This condition provides new insight into the evolutionary stability of source-sink systems. It also supports the hypothesis that immigrants have adapted demographic strategies, rather than the hypothesis that dispersal is costly and immigrants are at a disavantage compared with residents.
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  • 57
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    Hydrobiologia 365 (1997), S. 33-46 
    ISSN: 1573-5117
    Keywords: Phylogeny ; cladistics ; taxonomy ; systematics ; classification ; evolution ; history ; chronicle ; Nemertea ; Hoplonemertea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract I review how some influential nemertean systematistshave perceived and illustrated phylogenetic trees andargue that the nineteenth century nemerteantaxonomists still influence many contemporarynemertean taxonomists to a high degree. By showing hownineteenth century systematics differs from moremodern views on trees, I hope to convey the advantagesof a cladistic approach to tree-thinking and nemerteansystematics. Furthermore I propose a systematizationof the Eureptantia that illustrates the cladisticapproach to tree-thinking but, more importantly, isalso a better representation of eureptantic phylogenythan previous classifications.
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  • 58
    ISSN: 1573-3297
    Keywords: Aggression ; nest-building behavior ; wild house mice ; behavioral strategies ; bidirectional selection ; Y chromosome ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Psychology
    Notes: Abstract This study takes the first step toward testing a Y chromosomal effect on both aggression and thermoregulatory nest-building behavior in mouse lines either bidirecrionally selected for short (SAL) and long (LAL) attack latency or high (HIGH) and low (LOW) nest-building behavior. Using reciprocal crosses between SAL and LAL, and between HIGH and LOW, we found no indications for Y chromosomal effects on thermoregulatory nest-building behavior. As for aggression, we confirmed earlier studies on SAL and LAL, i.e., the origin of the Y chromosome influences attack latency, i.e., aggression. However, we did not find indications for a Y chromosomal effect on aggression in the HIGH and LOW lines. Since aggression and nest-building behavior have been shown to be characteristic parameters of two fundamentally different behavioral strategies, the present data underline the improbability of Y chromosomal genes underlying the genetic architecture of alternative behavioral strategies.
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  • 59
    ISSN: 1573-6849
    Keywords: comparative mapping ; evolution ; hominoids ; X–Y homologous genes ; Y chromosome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Several genes located within or proximal to the human PAR in Xp22 have homologues on the Y chromosome and escape, or partly escape, inactivation. To study the evolution of Xp22 genes and their Y homologues, we applied multicolour fluorescence in situ hybridization (FISH) to comparatively map DNA probes for the genes ANT3, XG, ARSD, ARSE (CDPX), PRK, STS, KAL and AMEL to prometaphase chromosomes of the human species and hominoid apes. We demonstrate that the genes residing proximal to the PAR have a highly conserved order on the higher primate X chromosomes but show considerable rearrangements on the Y chromosomes of hominoids. These rearrangements cannot be traced back to a simple model involving only a single or a few evolutionary events. The linear instability of the Y chromosomes gives some insight into the evolutionary isolation of large parts of the Y chromosomes and thus might reflect the isolated evolutionary history of the primate species over millions of years.
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  • 60
    ISSN: 1573-6849
    Keywords: chromosome banding ; citrus ; fluorochrome ; heterochromatin ; karyotype ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Double fluorochrome staining with chromomycin A3 (CMA) and 4′-6-diamidino-2-phenylindole (DAPI) was used to characterize and compare the distribution of constitutive heterochromatin along chromosomes of Citrus, Poncirus and Fortunella species. Only CMA-positive bands were distinguishable in metaphase chromosomes. Preferential distribution of heterochromatin in terminal regions, mainly of the long arm, and centromeric regions of a few long chromosomes was a common feature of these genera. Heteromorphism between possible homologous chromosomes was present in the majority of species. Citrus and Poncirus revealed some remarkably uniform chromosomes without any intensively fluorescing region, whereas Fortunella cultivars were differentiated by the presence of CMA bands in all chromosomes. Through measurements assisted by a computer, amounts of CMA-positive regions were shown to be highest in Fortunella. Similarities between Citrus and Poncirus suggest little heterochromatin diversification among karyotypes of these genera, whereas Fortunella, with higher amounts and more homogenous distribution of heterochromatin, is more divergent.
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  • 61
    ISSN: 1573-6849
    Keywords: evolution ; reptiles ; sex determination ; SRY ; ZFY
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the present investigation on the lizard Calotes versicolor, which lacks temperature-dependent sex determination, all the conventional cytological techniques used failed to resolve a distinguishable pair of sex chromosomes. However, probing of the genome with the human Y-linked genes SRY and ZFY showed sex-specific bias in their distribution. While the SRY probe hybridized to all the males, more than half of the females examined did not show any hybridization. ZFY hybridized to both the sexes, giving two bands; one was common to all the individuals of both sexes, but the other, of the lower molecular length, occurred in all the males but in less than 50% of females. This predominantly male-specific band is named AMF. The SRY-positive females were also positive for the AMF of ZFY. As positive as well as negative females were fertile and none of the males lacked SRY, it appears that SRY is essential for males only and that both the genes are syntenic in this species. This report raises interesting possibilities on the differentiation of the sex chromosomes in C. versicolor and evolution of SRY/ZFY on the Y chromosome of eutherian mammals through the ancestral group(s) that harbour sex-independent SRY- and ZFY-related genes.
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  • 62
    ISSN: 1573-5028
    Keywords: elongation ; gene expression ; glucanase ; Arabidopsis thaliana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The isolation of an elongation-specific endo-1,4-β-glucanase-cel1 from Arabidopsis thaliana was made possible by the fact that considerable homology exists between different endo-1,4-β-glucanase (EGase) genes from different plants. Degenerate primers were synthesized based on two conserved regions from the avocado and tomato cellulase amino acid sequences. The A. thaliana cel1 cDNA gene was found to encode a 54 kDa protein; sequence comparison with the avocado EGase revealed 56% identity. Northern blot analysis of cel1 suggested its developmental regulation. RNA transcripts were undetectable in fully expanded leaves as well as at the basal internode of flowering stems. However, a strong transcript signal was detected in the elongating zone of flowering stems of normal plants. The RNA transcript level of cel1 in the elongating zone of dwarf flowering stems was significantly lower than in the corresponding zone in normal plants. This suggests cel1's involvement in cell elongation in A. thaliana. Transgenic tobacco plants transformed with the putative cel1 promoter region fused to the gus reporter gene, showed a significant GUS staining both in shoot and root elongating zones. These results further substantiate the link between cel1 expression and plant cell elongation.
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  • 63
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    Plant molecular biology 35 (1997), S. 69-77 
    ISSN: 1573-5028
    Keywords: rice ; wild rice ; Oryza spp. ; evolution ; conservation ; evaluation ; utilization ; germplasm ; genetic resources ; genebank
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rice has been grown in Japan for about 3000 years. Although both japonica and indica varieties have been grown in Japan, now japonica rices are grown. Japanese rice breeding has used an ecological breeding approach. While emphasis in rice breeding in the 1940's and 1950's focussed on yield in recent decades quality has been of major importance. Consumer preference and name recognition of high quality varieties, such as Koshihikari, has resulted in slow acceptance of new varieties. Rice germplasm was systematically collected throughout Japan between 1962 and 1963. Subsequent acquisition and collecting, in Japan and other countries, has resulted in 28,000 accessions being conserved in the National Genebank, based at the National institute of Agrobiological Resources (NIAR). Research on genetic diversity of rice using a range of techniques, for example esterase isozymes, has revealed clinal variation in rice radiating from the center of diversity of rice in and around southwest China. Newly found genes in traditional rice germplasm, such as genes for non-elongating mesocotyl, are now routinely identified on the rice genome. Pioneering studies on eco-genetic differentiation of species in the genus Oryza in Japan has revealed much about the complex genepool for which rice evolved. Pest and disease resistance sources, particularly to blast, bacterial blight and brown plant hopper, from many countries have been incorporated into Japanese varieties. Cold tolerance at the booting stage was found in the Indonesian variety Silewah. In the future in characterisation of rice germplasm and interaction between rice germplasm specialists and rice molecular scientists, both in Japan and internationally, will be corner stones to securing rice genetic diversity and rice improvement in the next century.
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  • 64
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    Plant molecular biology 35 (1997), S. 293-302 
    ISSN: 1573-5028
    Keywords: Arabidopsis ; blue light ; gene expression ; Lhcb ; transcription
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Irradiation of etiolated Arabidopsis or pea, or dim-red-light-grown pea seedlings with a single, short (under 10 s) pulse of blue light (threshold at 0.1 µmol/m2) is sufficient to induce the expression of specific members of the Lhcb gene family including the pea Lhcb1*4 gene and the Arabidopsis Lhcb1*3 gene. Other Lhcb genes, such as the pea Lhcb1*3 gene and the Arabidopsis Lhcb1*1 and 1*2 genes are unaffected by this blue-light treatment. Transgenic Arabidopsis bearing pea Lhcb1*3::Gus (β-glucuronidase), pea Lhcb1*4::Gus or Arabidopsis Lhcb1*3::Gus constructs were used to determine if pea and Arabidopsis employ a similar mechanism to achieve blue-light induced Lhcb expression. Examination of the respective Gus expression patterns in white-light-grown seedlings indicates that the pea promoters are active and properly expressed in the Arabidopsis background. Irradiation of dark-grown Arabidopsis with a 20 s pulse of blue light with a total fluence of 100 µmol/m-2 results in expression of the pea Lhcb1*4::Gus (β-glucuronidase) construct, but not of the pea Lhcb1*3::Gus construct indicating that the pea promoters respond correctly to blue light in the Arabidopsis background. Fluence-response, time-course and reciprocity characteristics for the blue-light-induced expression of the pea Lhcb1*4::Gus construct closely resemble those of the endogenous Arabidopsis Lhcb genes, confirming the proper interpretation of the Arabidopsis blue-light-signaling mechanism by the pea Lhcb1*4 promoter and suggesting that the signaling mechanisms in the two plants are very similar, if not identical. Fluence response data for the steady-state level of transcript derived from an Arabidopsis Lhcb1*3::Gus construct extending 200 bp upstream of the site of transcription indicate that the blue light responsive element(s) are contained within this 200 bp region.
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  • 65
    ISSN: 1573-5028
    Keywords: Betula pendula Roth ; differential display ; gene expression ; mitochondria ; oxidative stress ; ozone ; phosphate translocator
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have isolated by DDRT-PCR (differential-display reverse-transcription polymerase chain reaction) and cDNA library screening a 1.3 kb cDNA corresponding to a strongly ozone-inducible transcript from birch (Betula pendula Roth). Nucleotide sequence analysis suggests that it encodes a mitochondrial phosphate translocator protein (Pi c), the first one isolated from plants. The isolated birch mitochondrial phosphate translocator cDNA (designated Mpt1) contains an open reading frame of 1092 bases encoding a 364 amino acid polypeptide. The deduced protein is 66% similar to bovine Pic isoform B. Comparison of the N-terminal amino acid sequence to known mammalian Pic proteins and the existence of an in-frame stop codon upstream of the initiation codon suggest that the isolated cDNA is full-length. Southern hybridization analysis of birch genomic DNA shows that Mpt1 is a single-copy gene. Accumulation of Mpt1 mRNA during oxidative stress imposed by ozone is detectable already at 2 h and it is at maximum ca. 12 h after the beginning of an 8 h ozone exposure (150 ppb). A second O3 peak at 48–56 h did not increase transcript levels further. O3 exposure for 2 h was sufficient for Mpt1 induction. Birch Mpt1 transcript levels remain at moderately low level during leaf development and is lower in roots and leaves when compared to young shoots undergoing wood formation and lignification.
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  • 66
    ISSN: 1573-5028
    Keywords: competitive PCR ; flavonoid pathway ; Forsythia ; gene expression ; transformation ; woody ornamentals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The expression, during flower development, of the gene encoding the anthocyanin pathway key enzyme dihydroflavonol 4-reductase (DFR) was investigated in floral organs of Forsythia × intermedia cv. ‘Spring Glory’. Full-length DFR and partial chalcone synthase (CHS) cDNAs, the gene of interest and a flavonoid pathway control gene respectively, were obtained from petal RNA by reverse transcription PCR. Whereas for CHS northern blot analysis enabled the study of its expression pattern, competitive PCR assays were necessary to quantify DFR mRNA levels in wild-type plants and in petals of 2 transgenic clones containing a CaMV 35S promoter-driven DFR gene of Antirrhinum majus. Results indicated a peak of CHS and DFR transcript levels in petals at the very early stages of anthesis, and different expression patterns in anthers and sepals. In comparison to wild-type plants, transformants showed a more intense anthocyanin pigmentation of some vegetative organs, and a dramatic increase in DFR transcript concentration and enzymatic activity in petals. However, petals of transformed plants did not accumulate any anthocyanins. These results indicate that other genes and/or regulatory factors should be considered responsible for the lack of anthocyanin production in Forsythia petals.
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  • 67
    ISSN: 1573-5028
    Keywords: integration ; geminivirus ; plant genomes ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Previously, we discovered multiple direct repeats of geminivirus-related DNA (GRD) sequences clustered at a single chromosomal position in Nicotiana tabacum (tobacco). Here we show that, in addition to tobacco, multiple copies of these elements occur in the genomes of three related Nicotiana species, all in the section Tomentosae: N. tomentosiformis, N. tomentosa and N. kawakamii, but not in 9 other more distantly related Nicotiana species, nor in various other solanaceous and non-solanaecous plants. DNA sequence analysis of 18 GRD copies reveal 4 distinct, but highly related, sub-families: GRD5, GRD3 and GRD53 in tobacco; GRD5 in N. tomentosiformis and N. kawakamii; and GRD2 in N. tomentosa. In addition to novel sequences, all elements share significant but varying lengths of DNA sequence similarity with the geminiviral replication origin plus the adjacent rep gene. There is extended sequence similarity to REP protein at the deduced amino acid sequence level, including motifs associated with other rolling circle replication proteins. Our data suggest that all GRD elements descend from a unique geminiviral integration event, most likely in a common ancestor of these Tomentosae species.
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  • 68
    ISSN: 1573-5028
    Keywords: cortex ; gene expression ; in situ hybridization ; organ-preferential ; root ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A near full-length cDNA clone (pZRP2) was isolated from a cDNA library constructed from maize root mRNAs. The predicted polypeptide has a calculated molecular mass of 66 975 Da, is largely hydrophilic, and contains 26 repeats of a motif the consensus sequence of which is RKATTSYG[S][D/E][D/E][D/E][D/E][P]. The function of the putative protein remains to be elucidated. The ZRP2 mRNA accumulates to the highest levels in young roots, and is also present in mature roots and stems of maize. Further analysis of young roots indicates that the lowest level of ZRP2 mRNA is near the root tip, with relatively high levels throughout the remainder of the root. In situ hybridization reveals that ZRP2 mRNA accumulates predominantely in the cortical parenchyma cells of the root. In vitro nuclear run-on transcription experiments indicate a dramatically higher level of zrp2 gene transcription in 3-day old roots than in 5-day old leaves. A zrp2 genomic clone, which includes the transcribed region and 4.7 kb of upstream sequence, was isolated and characterized.
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  • 69
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    Bioscience reports 17 (1997), S. 529-535 
    ISSN: 1573-4935
    Keywords: Mitochondria ; mt-dehydrogenase ; evolution ; insulin ; hormonal effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Mitochondrial dehydrogenase activity was measured in seven taxa of Tetrahymena (T. pyriformis G1, T. hegewishi, T. malaccensis, T. pigmentosa, T. shapiro, T. thermophila CU-399, T. thermophila MS-1). Enzyme activity was different in the taxa investigated. Insulin reduced enzyme activity in six of the seven taxa studied. The duration of activity reduction was relatively long (5–10 min.) in most of the cases, and in T. hegewishi this lasted up to the end of the measurements (30 min.). There was no interrelation between the basic dehydrogenase activity of the taxon and the effect of insulin. There was also no correlation between the degree of relationship (of the taxa) and the dehydrogenase profile after insulin treatment.
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  • 70
    ISSN: 1573-4935
    Keywords: Tetrahymena ; evolution ; hormones ; peptides ; signal molecule ; imprinting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Proline-glycine, proline-leucine and proline-valine dipeptides and their retro variants were used in the experiments to study the effects of pretreatment (imprinting) in Tetrahymena, by investigating fluorescein isothiocyanate (FITC)-conjugated peptide binding. The protozoan organism could differentiate between the proline-dipeptides containing different partner amino-acids and between the dipeptides having the amino acids in reversed positions. The effect of imprinting was positive or negative and this was dependent on the type of the partner amino acid and on its position. Pro-Gly and Pro-Leu induced positive imprinting (elevated FITC-dipeptide binding) and Pro-Val induced negative imprinting (decrease of FITC-peptide binding). There was positive imprinting induction in two cases for the retro FITC-peptide and in one case for the FITC-conjugate of the imprinter peptide itself. The highest positive imprinting (almost 60% increase) was induced by Pro-Gly for FITC-Gly-Pro. Considering earlier—chemotaxis—experiments, the results of the present—binding—studies run parallel with the physiological effects. The experiments call attention to the sharp differentiating ability of small peptides at a unicellular level, that could have some role in the selection of molecules for hormone formation, during evolution.
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  • 71
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    International journal of primatology 18 (1997), S. 455-467 
    ISSN: 1573-8604
    Keywords: Cebus ; Homo ; evolution ; Paleolithic art ; tool-use
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We examined modification of clay forms by tufted capuchins (Cebus apella) by presenting groups of subjects with clay, paint, stones, leaves, and sticks. In Experiment 1, 7 of 10 subjects reshaped portable forms with their hands and with stones, and decorated them with leaves and paint. In Experiment 2, 9 subjects marked clay slabs manually and with stick and stone tools. The manipulative propensities of Cebus can help us to understand psychological processes that underlie artistic expression in Homo and Pan.
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  • 72
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    Evolutionary ecology 11 (1997), S. 145-168 
    ISSN: 1573-8477
    Keywords: evolution ; Halticoptera laevigata ; host-marking pheromone ; parasitoids ; patch mark ; Tephritidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We found evidence for patch marking in the parasitic wasp Halticoptera laevigata (Hymenoptera: Pteromalidae) foraging for concealed hosts. Wasps attack larvae of the fruit fly Myoleja lucida (Diptera: Tephritidae) in fruits of honeysuckle. A special feature of this host-parasitoid system is the limited food supply of a patch (i.e. a fruit of honeysuckle), which allows the successful development of only a single host fly larva. Females of the parasitoid H. laevigata were found to mark the host patch with a pheromone and to abandon the patch following oviposition into a single host larva. Field data revealed that eggs of the parasitoid were spread out evenly among infested patches, with several larvae of the host fly left unparasitized in those patches that contained more than one host. Since many parasitic insects mark the parasitized host after oviposition, we assumed host marking to be the ancestral character state and studied the patch-marking behaviour of H. laevigata as a derived character state as an alternative foraging strategy. We used stochastic dynamic modelling to investigate under what conditions mutant (patch) markers would be able to invade a population of normal (larval) markers. The models suggested that, under a variety of conditions, wasps marking the patch obtained higher fitness than wasps only marking the larva. Consequently, the results from our model predict the evolution of the patch-marking behaviour found in the empirical investigation. Finally, we discuss alternative pathways to the evolution of patch marking and point out under what circumstances the evolution of a patch-marking behaviour can generally be expected.
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  • 73
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    Plant systematics and evolution 205 (1997), S. 1-25 
    ISSN: 1615-6110
    Keywords: Veroniceae ; Scrophulariaceae ; Flower shape ; flower development ; quantitative developmental character ; phylogeny ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Floral evolution in the tribeVeroniceae was examined using phylogenetic analysis combining 24 adult morphology and chromosome number characters with 22 qualitative and quantitative floral development characters. Taxa sampled included nine species ofVeroniceae and as an outgroup one species each ofDigitaleae andVerbasceae. Veronica, Besseya, andSynthyris formed one clade, subtended byPseudolysimachion and then by theHebe group;Veronicastrum orWulfenia represent the basal-most branch of the tribe. The ancestral flowers of theVeroniceae may have been small with moderately short corolla tubes and lobes; long corolla tubes arose four times in the tribe and large corolla lobes twice.
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  • 74
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    Plant systematics and evolution 208 (1997), S. 71-97 
    ISSN: 1615-6110
    Keywords: Geraniaceae ; Pelargonium ; Bees ; beeflies ; birds ; butterflies ; long-proboscid flies ; convergence ; evolution ; floral ecology ; pollination ; pollination guilds ; pollination syndromes ; Southern Africa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Based on field observations and a survey of the available literature, the functional and evolutionary significance of floral characters ofPelargonium is investigated in relation to a recent infrageneric re-classification. Most of the 208Pelargonium taxa (recognized as species, subspecies or varieties) involved show bee and long-proboscid hovering fly pollination syndromes (about 60% and 25%, respectively), only 7% of the taxa are pollinated by butterflies, some 2 to 4% by hawkmoths and presumably 1% by birds. The heterogeneity ofPelargonium in terms of structural blossom types and pollination syndromes indicates an independent and repeated evolution of convergent flower morphs in the genus and even in sections.
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  • 75
    ISSN: 1615-6110
    Keywords: Brassicaceae ; Cardamine amara ; C. ×insueta ; C. rivularis ; C. schulzii ; Hybridization ; evolution ; amphiploidy ; introgression ; cpDNA ; isozymes ; RAPD
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Hybridization between two diploid (2n = 2x = 16) species ofBrassicaceae, Cardamine rivularis andC. amara, at Urnerboden, Central Switzerland, resulted in the rather unusual triploid hybridC. insueta (2n = 3x = 24), and later on in the amphiploidC. schulzii (2n = 6x = 48). The hybrid and the neopolyploid species colonized successfully some man-made biotopes. Plants ofC. insueta are mostly functional females with non-dehiscent anthers, but true hermaphrodite individuals with partly sterile pollen grains also occur within the population. Analyses of cpDNA and nuclear DNA permitted to establish the parentage of the hybrid: the maternal parent which contributed unreduced egg cells proved to beC. rivularis whereas the normally reduced pollen originated fromC. amara. The pronounced genetic variability inC. insueta revealed by isozyme and RAPD analyses, at variance with the polarized segregation, heterogamy and strong vegetative reproduction of the hybrid, is possibly influenced by recurrent formation ofC. insueta which party results from backcrosses betweenC. insueta andC. rivularis but may also proceed by other pathways. The amphiploidCardamine schulzii has normally developed anthers but its pollen is sometimes highly sterile. The surprisingly uniform genetic make-up of the new amphiploid species might be related to its possible monotopic origin and/or young phylogenetic age but should be further assessed. Site management seems to be very important to a further development of hybridogenous populations and their parent species. In conclusion, the evolution at Urnerboden is discussed in the context of the traditional concept of multiple plant origins.
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  • 76
    ISSN: 1573-5060
    Keywords: ethylene ; gene expression ; Hevea brasiliensis ; latex coagulation ; rubber ; somatic embryogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The latex from Hevea brasiliensis is expelled from specialized cells upon bark tapping. The latex yield is mainly limited by the duration of the latex flow, which is controlled by coagulation processes. Bark treatment with ethylene is known to delay coagulation and increase latex yield. The molecular basis of latex coagulation has been characterized: (1) Hevein, a lectin-like protein, induces latex coagulation by bringing together the rubber particles (RPs). The hevein-RPs bridging is mediated by N-Acetyl-D-glucosamine, and involves a 22 kDa receptor glycoprotein localized on the RPs surface. This process is inhibited by the removal of the sugar moiety from the receptor, through the action of N-acetyl-glucosaminidase and chitinases. (2) Ethylene induces, in the latex cells, an over-expression of the 3 genes coding for hevein and its receptor, and a chitinase. The higher over-expression of one chitinase can explain the partial deglycosylation of the hevein receptor and the resulting delay in coagulation. (3) The level of hevein and chitinase expression in the latex is a clonal characteristic, linked to the characteristics of the latex flow. Expression of these genes might be used as molecular markers for high yield potential. Based on these findings, it would be interesting to improve the rubber tree through the genetic engineering technics, to get new high yielding cultivars with prolonged latex flow.
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  • 77
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    Genetic resources and crop evolution 44 (1997), S. 327-335 
    ISSN: 1573-5109
    Keywords: Cocos nucifera ; diversity ; evolution ; germplasm ; genetic resources ; morphology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The south Pacific region contains a large genetic resource for the genetic improvement of coconut palms (Cocos nucifera L.). A study of the diversity in the species was made during 1992/3 using fruit component analysis on a representative sample from 29 distinct south Pacific populations in order to characterise the germplasm present in the region. A large diversity in fruit morphology was found that ranged from populations exhibiting wild-type characters in central Pacific to populations displaying domesticated characteristics in Rennell Island, the Sikaiana Islands, the Marquesas Islands, and in Papua New Guinea. Many populations exhibited fruit characteristics intermediate between the two, which were thought to have arisen due to introgressive hybridisation between the wild and domesticated populations. Continuous variation in fruit morphology was found in these populations, and cluster analysis arbitrarily divided the continuum into discrete groups which were consistent with geographic affinities. Groups were defined in Melanesia, Western Polynesia and Eastern Polynesia. The continuum displayed clinal variation from populations with small fruit and low husk content in the west to large fruit and more husk in the east of the region. The wild and domesticated populations were found in disjunct pockets throughout the area, and did not form part of the clines. Most populations consisted of a wide range of fruit morphology, from individuals expressing wild-type characters to those with domestic-type characters. The occurrence of both wild and domesticated populations within the clinal variation indicates that further exploration should be made to determine the presence of other potentially useful populations. While this activity is proceeding, collection and conservation can proceed using the classification already defined.
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    Environmental biology of fishes 48 (1997), S. 127-155 
    ISSN: 1573-5133
    Keywords: sturgeon ; paddlefish ; Huso ; Acipenser ; Scaphirhynchus ; Pseudoscaphirhynchus ; Polyodon ; Psephurus ; karyotype ; chromosome ; macrochromosome ; microchromosome ; genome ; DNA content ; 18S rRNA gene ; cytochrome ; 12S mtrRNA gene ; 16s mtrRNA gene ; rate of molecular evolution ; phylogeny ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The review of the data on karyology and DNA content in Acipenseriformes shows that both extant families, the Polyodontidae and Acipenseridae, originated from a tetraploid ancestor which probably had a karyotype consisting of 120 macro- and microchromosomes and DNA content of about 3.2–3.8 pg per nucleus. The tetraploidization of the presumed 60-chromosome ancestor seems to have occurred at an early time of evolution of the group. The divergence of the Acipenseridae into Scaphirhyninae and Acipenserinae occurred without polyploidization. Within the genus Acipenser, polyploidization was one of the main genetic mechanisms of speciation by which 8n and 16n-ploid species were formed. Individual gene trees constructed for sequenced partial fragments of the 18S rRNA (230 base pairs, bp), 12S rRNA (185 bp), 16S rRNA (316 bp), and cytochrome b (270 bp) genes of two Eurasian (A. baerii and A. ruthenus) and two American (A. transmontanus and A. medirostris) species of Acipenser, Huso dauricus, Pseudoscaphirhynchus kaufmanni, Scaphirhynchus albus, and Polyodon spathula showed a low level of resolution; the analysis of a combined set of data for the four genes, however, gave better resolution. Our phylogeny based on molecular analysis had two major departures from existing morphological hypotheses: Huso dauricus is a sister-species to Acipenser instead of being basal to all acipenseriforms, and Scaphirhynchus and Pseudoscaphirhynchus do not form a monophyletic group. The phylogenetic tree constructed for the cytochrome b gene fragments (with inclusion of 7 additional species of Acipenser) supported the conclusion that octoploid species appeared at least three times within Acipenser.
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    Fish physiology and biochemistry 17 (1997), S. 143-153 
    ISSN: 1573-5168
    Keywords: goldfish ; activin ; inhibin ; receptors ; perifusion ; immunocytochemistry ; cloning ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Activin (βAβA, βAβB and βBβB) is a dimeric protein that belongs to the transforming growth factor-β (TGF-β) superfamily of growth factors and is involved in the regulation of many physiological and developmental processes. Recently, we have demonstrated that porcine activin stimulated goldfish gonadotropin-II (GTH-II) and growth hormone (GH) secretion from dispersed pituitary cells in static culture and pituitary fragments in perifusion. The action of activin in the goldfish is unique in that it has an acute stimulatory effect on the secretion of GTH-II and GH, whereas in mammals activin usually exhibits long-term stimulatory actions on FSH secretion. The action mechanism of activin is different from that of gonadotropin-releasing hormone (GnRH). Using domain-specific antibodies against mammalian activin subunits, we subsequently demonstrated the existence of immunoreactive activin subunits (βA and βB) in the goldfish ovary, testis, pituitary and brain, suggesting endocrine, paracrine and autocrine roles for activin in the regulation of goldfish reproduction. Both activin βA and βB subunits have been cloned from goldfish genome by polymerase chain reaction (PCR). Using the PCR fragments as probes, we have cloned a full length cDNA coding for activin βB subunit from the goldfish ovary. Both activin βA and βB subunits show high homology to those of other vertebrates with the βB subunit much more conserved (93 and 98% identity with human and zebrafish βB subunit, respectively). The identity of the cloned βB subunit was further confirmed by expression in the Chinese hamster ovary (CHO) cells and detection of the specific activity of activin in the culture medium. The messenger RNA of activin βB subunit is expressed in a variety of goldfish tissues including ovary, testis, brain, pituitary, kidney and liver, suggesting a wide range of physiological roles for activin in the goldfish. We have also cloned a full length cDNA coding for the activin Type IIB receptor from the goldfish ovary, suggesting that activin may have paracrine or autocrine actions on the ovarian functions. The identity of the cloned receptor was confirmed by specific binding of125 I-activin on COS-1 cells transfected with the cloned Type IIB receptor.
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  • 80
    ISSN: 1573-5168
    Keywords: precursor proteins of egg envelope ; choriogenin H ; choriogenin L ; estrogen receptor ; estrogen ; vitellogenin ; oogenesis ; choriogenesis ; gene expression ; transcriptional factor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The time course and pattern of expression of the genes for choriogenin H and choriogenin L in the liver of the E2-treated male fish was investigated according to the methods of dot blotting analysis and in situ hybridization. Four hours after the beginning of estrogen treatment (final concentration in rearing water: 100 ng ml-1), expression of the choriogenins genes was induced in every parenchymal cell in the liver and the amounts of the gene transcripts were generally increased. As a primary step for analysis of the mechanism of the estrogen action, the amount of estrogen receptor and expression of its gene were examined in the liver of estrogen-treated male fish.
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  • 81
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    Plant molecular biology 35 (1997), S. 711-721 
    ISSN: 1573-5028
    Keywords: fermentation ; gene expression ; lactate dehydrogenase ; oxygen deficit ; root ; tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two different cDNAs encoding lactate dehydrogenase (LDH) were isolated from a library of hypoxically treated tomato roots and sequenced. The use of gene-specific probes on northern blots showed that Ldh2 mRNA was predominant in well-oxygenated roots and levels remained stable upon oxygen deficit; in contrast, Ldh1 mRNA accumulated to high levels within 2 h of hypoxia or anoxia. Immunoblot analyses of native gels using a polyclonal antiserum raised against an LDH1 fusion protein indicated that LDH2 homotetramer was the major isoform present in aerobic roots. Levels of both LDH1 and LDH2 subunits increased during an 18 h hypoxic treatment, together with a 5-fold rise in activity. These results suggest that the regulation of ldh1 expression is primarily at the transcriptional level while that of ldh2 is post-transcriptional. Increases in Ldh1 mRNA and LDH activity were not correlated with lactic acid production, which was maximal at the onset of anoxia in unacclimated roots and then declined. Taken together, our results indicate that LDH2 present in aerobic roots is principally responsible for lactic acid production occurring transiently upon imposition of anoxia. Possible physiological roles for LDH1 are discussed.
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  • 82
    ISSN: 1573-5028
    Keywords: ethylene ; gene expression ; thiamine ; fruit ripening ; Citrus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Maturing citrus fruit undergo pigment changes which can be enhanced by exogenous ethylene. In order to identify genes induced by ethylene in citrus fruit peel, we cloned the gene c-thi1. mRNA corresponding to c-thi1 increased gradually in the peel during natural fruit maturation and in response to ethylene. GA3 pretreatment reduced the inductive effect of ethylene. Levels of c-thi1 increased also in juice sacs but the effect of ethylene was much less prominent. c-thi1 is homologous to yeast and plant genes encoding for an enzyme belonging to the pathway of thiamine biosynthesis. The data suggest that thiamine is involved in citrus fruit maturation.
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  • 83
    ISSN: 1573-5028
    Keywords: aspartic protease ; barley ; gene expression ; nucellar cell ; nucellin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The nucellar cells of barley undergo progressive degeneration after ovule fertilization. This degeneration is a characteristic of programmed cell death. Increasing evidence has indicated that proteases are important regulators of programmed cell death in animals. We have cloned and characterized a barley gene which encodes an aspartic protease-like protein and is specifically expressed in nucellar cells during degeneration. The gene contains eight exons and seven introns and encodes a polypeptide of 410 amino acid residues. The deduced polypeptide is characterized by having two aspartic protease catalytic site motifs, the Asp-Thr-Gly-Ser in the N-terminal and Asp-Ser-Gly-Ser in the C-terminal region, and two other regions nearly identical to two regions of plant aspartic proteases. However, it shares 〈20% overall sequence identity with the known plant aspartic proteases, and does not contain a ‘prosequence’ or a ‘plant-specific insert’ which are characteristics of plant aspartic proteases. We have named this aspartic protease-like protein ‘nucellin’. In northern analyses nucellin transcripts were most abundant in ovaries 3–4 days after pollination, but only marginally detectable before pollination or 10 days after pollination. RNA in situ hybridization showed that before pollination the nucellin gene was expressed at a very low level only in a cluster of nucellar cells close to the embryo sac at the chalazal end, but after pollination it was highly expressed in most nucellar cells surrounding the entire embryo sac. Furthermore, no nucellin transcripts were detectable in anther, leaf, or root tissue. The temporal and spatial pattern of the nucellin gene expression is synchronal with nucellar cell degeneration and thus, nucellin may be involved with nucellar cell death.
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  • 84
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    Genetica 99 (1997), S. 173-184 
    ISSN: 1573-6857
    Keywords: evolution ; genetics ; neurophysiology ; philosophy ; politics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract On first impression, the disciplines of genetics and political science would appear to be unrelated. And yet, commencing more than 30 years ago, the interdisciplinary field known as Biopolitics has now taken hold. This essay traces the central thrust of the biopolitical research agenda. It describes, analyzes, and assesses how political scientists have sought to show connections between our species' genetic constitution and our species' political behavior. Important bridges between the two are the neurophysiology of the human brain and the role of evolutionary theory in charting man's adaptational political profile. The parameters of the emerging biopolitical literature raise profound policy questions, some of which are also characterized.
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  • 85
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    Journal of bioenergetics and biomembranes 29 (1997), S. 109-119 
    ISSN: 1573-6881
    Keywords: ETS domain ; gene expression ; mammalian cells ; mitochondria ; nuclear respiratory factors ; oxidative phosphorylation ; regulation ; respiratory chain ; transcription
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The majority of gene products required for mitochondrial respiratory function are encoded in the nuclear genome. These include most of the respiratory subunits and all of the proteins that regulate the mitochondrial genetic system. One approach to understanding nucleo-mitochondrial interactions in mammalian cells is to identify the nuclear transcription factors that are common to the expression of these gene products. This has led to the purification and molecular cloning of nuclear respiratory factors, NRF-1 and NRF-2. The DNA binding and transcriptional specificities of these proteins have implicated them in the expression of many respiratory subunits along with key components of the mitochondrial transcription, replication, and heme biosynthetic machinery. In addition, tissue-specific transcription factors have been linked to the coordinate synthesis of contractile proteins and muscle-specific respiratory subunits whereas other more ubiquitous factors may have a dual function in nuclear and mitochondrial gene activation. These findings provide a framework for further investigations of the nuclear genetic mechanisms that integrate the expression of the respiratory apparatus with that of other cellular systems during growth and development.
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  • 86
    ISSN: 1573-6857
    Keywords: evolution ; heterochromatin ; retrotransposable elements ; telomerase ; telomeres
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transposable elements are abundant in the genomes of higher organisms but are usually thought to affect cells only incidentally, by transposing in or near a gene and influencing its expression. Telomeres of Drosophila chromosomes are maintained by two non-LTR retrotransposons, HeT-A and TART. These are the first transposable elements with identified roles in chromosome structure. We suggest that these elements may be evolutionarily related to telomerase; in both cases an enzyme extends the end of a chromosome by adding DNA copied from an RNA template. The evolution of transposable elements from chromosomal replication mechanisms may have occurred multiple times, although in other organisms the new products have not replaced the endogenous telomerase, as they have in Drosophila. This is somewhat reminiscent of the oncogenes that have arisen from cellular genes. Perhaps the viruses that carry oncogenes have also arisen from cellular genetic systems.
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  • 87
    ISSN: 1573-6857
    Keywords: long terminal repeat retrotransposon ; transposable element ; enhancer ; gene expression ; copia/Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Since LTR retrotransposons and retroviruses are especially prone to regional duplications and recombination events, these viral-like systems may be especially conducive to the evolution of closely spaced combinatorial regulatory motifs. Using the Drosophila copia LTR retrotransposon as a model, we show that a regulatory region contained within the element's untranslated leader region (ULR) consists of multiple copies of an 8 bp motif (TTGTGAAA) with similarity to the core sequence of the SV40 enhancer. Naturally occurring variation in the number of these motifs is correlated with the enhancer strength of the ULR. Our results indicate that inter-element selection may favor the evolution of more active enhancers within permissive genetic backgrounds. We propose that LTR retroelements and perhaps other retrotransposons constitute drive mechanisms for the evolution of eukaryotic enhancers which can be subsequently distributed throughout host genomes to play a role in regulatory evolution.
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  • 88
    ISSN: 1573-6857
    Keywords: biodiversity ; copia ; evolution ; genome organization ; retrotransposon ; Ty element
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Ty1-copia group of LTR retrotransposons has been studied extensively in yeast and Drosophila, the organisms in which they were first discovered, and more recently in higher plant and vertebrate species. Their properties, such as copy number, sequence homogeneity, transcriptional and transpositional activity vary greatly between these different hosts. We will try to resolve these apparent discrepancies between these properties, explain any fundamental differences in the biology of the Ty1- copia group between hosts, and propose a general model for LTR retrotransposon evolution.
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  • 89
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    Genetica 100 (1997), S. 231-240 
    ISSN: 1573-6857
    Keywords: barley ; evolution ; Hordeum ; retrotransposon ; Ty1-copia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In our search for transposable elements in barley, Hordeum vulgare, we have isolated and cloned two BamHI-fragments of 4.7 and 4.2 kb in length containing very abundant DNA sequences. The 4.7 kb fragment is homologous to the extended region, including more than half of the 5′-LTR and some part of the coding domain of BARE-1, a member of copia-like retrotransposon family of barley. The 4.2 kb fragment, bearing homology to BARE-1 and the WIS-2 family isolated from wheat, is unique among studied retroelements of cereals because it consists of two inverted parts, each containing homology to the LTR and UTL of BARE-1. Functional motifs for reverse transcription, two TATA-boxes and two primer-binding sites, were found within the LTRs. The element contained within this fragment was generated by significant rearrangement of a BARE-like retrotransposon, which included inversion of the extended 5′-terminal region and deletion of the internal domain. Therefore this element is named BARE-ID (BARE-inverted, deleted). A family of BARE-like elements is amplified in the H. vulgare genome compared with wild barley species. The terminal inverted repeat of BARE-ID was used as a probe for examination of evolutionary diversity within genus Hordeum. Our data are basically in agreement with the modern classification system. However, they do not support the combination of H. vulgare and H. bulbosum into one group with the same type of genome. New data concerning the possible origin of the polyploid species, H. secalinum, confirm that retrotransposons are a useful tool for phylogenetic studies.
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  • 90
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    Genetica 99 (1997), S. 173-184 
    ISSN: 1573-6857
    Keywords: evolution ; genetics ; neurophysiology ; philosophy ; politics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract On first impression, the disciplines of genetics and political science would appear to be unrelated. And yet, commencing more than 30 years ago, the interdisciplinary field known as Biopolitics has now taken hold. This essay traces the central thrust of the biopolitical research agenda. It describes, analyzes, and assesses how political scientists have sought to show connections between our species' genetic constitution and our species' political behavior. Important bridges between the two are the neurophysiology of the human brain and the role of evolutionary theory in charting man's adaptational political profile. The parameters of the emerging biopolitical literature raise profound policy questions, some of which are also characterized.
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  • 91
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    Chromosome research 5 (1997), S. 125-131 
    ISSN: 1573-6849
    Keywords: gene expression ; nucleolar dominance ; rDNA ; substitution lines ; triticale
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Hybrid plants and animals often show suppression of activity of ribosomal genes (rDNA) originating from one of the parental or ancestral species. In the wheat × rye amphiploid triticale, containing 28 chromosomes of wheat origin and 14 from rye, rDNA of rye origin (on chromosome 1R) is not normally expressed, while the 1B- and 6B-origin rDNA from wheat shows strong expression. Expression of rDNA can be accurately assessed by the silver staining method, which stains both interphase nucleoli and metaphase rDNA sites that were actively expressed at the previous interphase. We show here that substitution of another rye chromosome, 2R, by a chromosome from hexaploid wheat, 2D(triticale-2D(2R)), prevents suppression of the rye-origin rDNA, and leads to activity of all six major rDNA loci. These results were found in two different triticales and supported by rDNA behaviour in wheat—rye chromosomal addition lines. Models for chromosomal interactions leading to control of rDNA expression are presented.
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  • 92
    ISSN: 1573-6849
    Keywords: Ateles geoffroyi ; chromosome painting ; cytogenetics ; evolution ; phylogeny ; Platyrrhini ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We hybridized human chromosome-specific DNA probes to metaphases of the New World monkey Ateles geoffroyito map the chromosomal homology between these two species. In the haploid Ateles geoffroyi karyotype the total number of signals was 51 for the 22 human autosomal probes used. Compared with Old World monkeys, the number of translocations found in the black-handed spider monkey karyotype was quite striking. The majority of these translocations are apparently Robertsonian and no reciprocal translocations were revealed. Nine autosomal human chromosome probes (11, 13, 14, 17, 18, 19, 20, 21, 22) provided only two signals each per metaphase, but six of these were translocated to subregions of different spider monkey chromosomes. The other 13 autosomal human chromosome paints (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 16) provided fragmented signals. Three human probes (5, 8, 10) provided signals located on two pairs of spider monkey chromosomes. Four human paints (2, 3, 4, 12) provided hybridization signals on three pairs of chromosomes. Probes 6, 7, 15 provided six signals each on two pairs of chromosomes; probe 16 gave eight signals on two pairs of spider monkey chromosomes and probe 1 gave 12 signals on four pairs of chromosomes. The synteny between segments to human 18/8 appears to be an apomorphic ancestral condition for all New World monkeys. A synteny between regions homologous to human 16/10, 5/7 and 2/16 HSA is probably an apomorphic ancestral condition for all Cebidae. The syntenic association 3/15 and 4/1 is an apomorphic condition for the Atelinae.
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  • 93
    ISSN: 1573-6849
    Keywords: chromosome ; evolution ; comparative mapping ; Indian muntjac ; satellite DNA ; zoo-fluorescence in situ hybridization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Zoo-fluorescence in situ hybridization (FISH) with human whole chromosome-specific paint probes revealed extensive homoeologies between Indian muntjac (2n=6, 7 female, male) and human karyotypes (2n=46). Forty-two conserved syntenic segments, corresponding to all human chromosomes except the Y chromosome, produced a near-complete coverage of the muntjac complement and revealed margins of interspecific segmental homoeology. To test the hypothesis that interstitial satellite DNA loci, illuminated by a Chinese muntjac C5-satellite probe in Indian muntjac chromosome arms, mark ancestral fusion points (Lin CC, Sasi R, Fan YS, Chen Z-Q (1991) New evidence for tandem chromosome fusions in the karyotypic evolution of the Asian muntjacs. Chromosoma 101: 19–24), we combined Zoo-FISH with C5 satellite mapping. Twenty-six interstitial satellite DNA loci were detected in the haploid Indian muntjac genome and were found to co-localize with the margins of conserved human/Indian muntjac syntenic segments. These results were confirmed by two-colour FISH and are in accordance with the tandem fusion hypothesis for Indian muntjac chromosomes. Furthermore, conserved syntenic segment combinations detected in pig, cattle and Indian muntjac Zoo-FISH maps reveal ancestral artiodactyl chromosomes.
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  • 94
    ISSN: 1573-6857
    Keywords: Ty1-copia ; retrotransposons ; retroelements ; plants ; genomic organisation ; evolution ; molecular marker
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The genomic organisation and diversity of the Ty1-copia group retrotransposons has been investigated in several crop plants and their relatives from both dicotyledonous and monocotyledonous families, including potato ( Solanum tuberosum), faba beans ( Vicia faba), Vicia melanops, Vicia sativa, barley ( Hordeum vulgare), rye ( Secale cereale), and onion ( Allium cepa). Extreme heterogeneity in the sequence of the Ty1-copia retrotransposons from all these plants was revealed following sequence analysis of reverse transcriptase fragments. The estimated copy numbers of the Ty1-copia group retrotransposons for the genomes of S. tuberosum, L. esculentum, A. cepa, S. cereale, and V. faba is highly variable, ranging from a few hundred to approximately a million copies per genome. In situ hybridisation data from metaphase and prophase chromosomes of V. faba, S. cereale, and H. vulgare suggest that retrotransposon sequences are dispersed throughout the euchromatic regions of the genome but are almost undetectable in most heterochromatic regions. In contrast, similar data from metaphase chromosomes of A. cepa suggests that although retrotransposon sequences are dispersed throughout the euchromatic regions of the genome, they are predominantly concentrated in the terminal heterochromatin. These results are discussed in the context of the role played by the Ty1-copia group retrotransposons in the evolution of the plant genome. Lastly, the application of retrotransposon sequences as genetic markers for mapping genomes and for studying genetic biodiversity in plants is presented.
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  • 95
    ISSN: 1573-6857
    Keywords: evolution ; Lacertadahli ; parthenogenesis ; uniparentality ; unisexuality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Allozyme variation at 35 gene loci is investigated in 161 specimens of the uniparental Caucasian lizard Lacerta dahli from several locations in Armenia and Georgia. All individuals are heterozygotic at 12 loci, and homozygotic at 21 loci. Variation at two loci results in five uniparental clones. One clone is widespread whereas four are geographically restricted and are represented by only one or two individuals. Because successful formation of uniparental clones is rare, and because the biparental species forming them are now allopatric, the most probable explanation for the origin of the observed clonal diversity is either mutation or recombination within the common clone. The rare clones have lower levels of enzyme activity at four loci, suggesting that these organisms may be genetically deficient. Although the evidence points to change in a pre-existing clone, the possibility of multiple origins cannot be ruled out.
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  • 96
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    Photosynthesis research 51 (1997), S. 27-42 
    ISSN: 1573-5079
    Keywords: Photosystem I ; Photosystem II ; photosynthetic reaction center ; bacteriorhodopsin ; evolution ; UV-protection ; t Rhodopseudomonasviridis ; t Heliobacillus mobilis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Sequence alignments between membrane-spanning segments of pheophytin-quinone-type photosynthetic reaction centers, FeS-type photosynthetic reaction centers, core chlorophyll-proteins of PS II, chlorophyll t a/t b-containing antenna proteins of plants and light-harvesting complexes of purple bacteria led us to postulate a large common ancestral pigment-carrying protein with more than 10 membrane spans. Its original function as a UV-protector of the primordial cell is discussed. It is conceivable that a purely dissipative photochemistry started still in the context of the UV-protection. We suggest that mutations causing the t loss of certain porphyrin-type pigments led to the acquisition of redox cofactors and paved the way for a gradual transition from dissipative to productive photochemistry.
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  • 97
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    Environmental and resource economics 9 (1997), S. 429-449 
    ISSN: 1573-1502
    Keywords: evolution ; economics ; pesticide resistance ; antibiotic resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Economics
    Notes: Abstract The employment of insecticides raises the relative fitness of resistant insects; the use of antibiotics applies selection pressure in favour of resistant strains of bacteria; lower limits on fish net mesh size raises the advantages of smaller adults. These are some of the many examples of the unintended impact of human activity upon biological evolution. Often this evolution has economic significance, as it does in the examples quoted. This paper examines some of the principles involved and provides a preliminary analysis of the extent to which the economically optimal inducement of evolution differs from that arising when changes in selection pressures are not anticipated.
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  • 98
    ISSN: 1573-1561
    Keywords: Scolytidae ; Ips ; Orthotomicus ; Pinus ; evolution ; cuticular hydrocarbons ; chemotaxonomy ; methyl-branched hydrocarbons ; mass spectrometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Cuticular hydrocarbons were extracted, identified, and evaluated as chemotaxonomic characters from all species of adult Ips pine engraver beetles in the grandicollis subgeneric group. The grandicollis group consists of Ips grandicollis (Eichhoff), I. cribricollis (Eichhoff), I. lecontei Swaine, I. montanus (Eichhoff), I. paraconfusus Lanier, I. confusus (LeConte), and I. hoppingi Lanier. In order to provide outgroups for a phylogenetic analysis, cuticular hydrocarbons were also analyzed from Orthotomicus caelatus (Eichhoff), I. latidens (LeConte) (latidens subgeneric group), and I. pini (Say) (pini subgeneric group). Two hundred forty-eight hydrocarbon components were identified by gas chromatography–mass spectrometry. The members of the grandicollis group provided 206 of these compounds. The components represented eight classes: n-alkanes, alkenes, alkadienes, terminally branched methylalkanes, internally branched methylalkanes, dimethylalkanes, trimethylalkanes, and tetramethylalkanes. Different populations of O. caelatus, I. grandicollis, I. lecontei, I. montanus, I. paraconfusus, I. confusus, and I. hoppingi provided no evidence for interpopulational variation in cuticular hydrocarbons. Single populations only were analyzed for I. latidens, I. pini, and I. cribricollis. Sexual dimorphism in cuticular hydrocarbons occurred only in I. lecontei where females produced eight unique components with a pentatriacontane parent chain. Several phylogenetic analyses based on hydrocarbon phenotypes agreed in general with the established morphologically based system of relatedness and with published phylogenies reconstructed from protein and nucleic acid characters. Nearly all hydrocarbon analyses suggested a close relationship between I. grandicollis and I. cribricollis; between I. lecontei and I. montanus; and among the sibling species I. paraconfusus, I. confusus, and I. hoppingi. The presence or absence of specific n-alkanes (n-docosane, n-triacontane); certain dimethylalkanes (terminally branched with octacosane and triacontane parent chains and internally branched with heptacosane, hentriacontane, and docotriacontane parent chains); and 3,7,11-; 3,7,15-trimethylheptacosane permit facile discrimination of I. paraconfusus, I. confusus, and I. hoppingi. These three sibling species are difficult to resolve by external morphology. These data support the species status of I. hoppingi rather than it being considered a host race of the I. confusus complex. They also support the species status of I. cribricollis rather than it being considered part of I. grandicollis. In contrast to other published phylogenies reconstructed from molecular data, phylogenies reconstructed from cuticular hydrocarbons repeatedly place I. lecontei as an integral part of the grandicollis subgeneric group. Thus, cuticular hydrocarbon and pheromone alcohol composition of I. lecontei support its inclusion in the grandicollis subgeneric group.
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  • 99
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    Experimental and applied acarology 21 (1997), S. 551-559 
    ISSN: 1572-9702
    Keywords: Ticks ; Hyalomma truncatum ; feeding performance ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In order to determine the effect of various hosts on the feeding performance of the tick Hyalomma truncatum, we used three mammalian species as hosts. Larvae and nymphs of H. truncatum were fed, under controlled laboratory conditions, on gerbils, guinea-pigs and rabbits. The larvae fed for 4.3±1.4 days on gerbils, 5.6±1.3 days on guinea-pigs and 4.7±1.2 days on rabbits. The mean weights of the larvae which fed on the rabbits, guinea-pigs and gerbils were 0.58± 0.09, 0.46±0.04 and 0.45±0.04 mg. respectively. The feeding periods of the nymphs on gerbils, guinea-pigs and rabbits were 7.9±1.3, 8.6±1.3 and 9.6±2.2 days respectively. The mean weights of the nymphs which fed on the gerbils, guinea-pigs and rabbits were 22.5±2.8, 19.7±1.3 and 15.8±1.4 mg, respectively. Hyalomma truncatum demonstrated a life cycle of a three-host tick on gerbils and guinea-pigs and of a two-host tick on rabbits. The evolutionary advantage of a two-host cycle over a three-host cycle in metastriate ticks is discussed.
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  • 100
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    Antonie van Leeuwenhoek 71 (1997), S. 271-276 
    ISSN: 1572-9699
    Keywords: bacteria ; evolution ; molecular ; silicon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This review examines the possible role of silicon in molecular evolution. It is possible silicon participated in early molecular evolution by providing a stable mineral surface or gel structure where the assembly and replication of primitive genetic information occurred. However, as molecular evolution proceeded, silicon was not required in the evolution of C-based organisms. Silicon can be accumulated by diatoms and other living organisms such as silicoflagellates, some xanthophytes, radiolarians and actinopods and plants such as grasses, ferns, horseradish, some trees and flowers, some sponges, insects and invertebrates and bacteria and fungi. Silicon also has a role in synthesis of DNA, DNA polymerase and thymidylate kinase activity in diatoms. It is not unreasonable to examine the role of silicon in early molecular evolution as it may have been part of a micro-environment in which assembly of genetic information occurred.
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