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  • Evolution
  • Springer  (38)
  • American Meteorological Society
  • 1995-1999  (38)
  • 1990-1994
  • 1970-1974
  • 1965-1969
  • 1998  (38)
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  • 1995-1999  (38)
  • 1990-1994
  • 1970-1974
  • 1965-1969
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  • 1
    Electronic Resource
    Electronic Resource
    Olfactory receptors in aquatic and terrestrial vertebrates (1998)
    Springer
    Journal of comparative physiology 183 (1998), S. 635-650 
    Details
    ISSN: 1432-1351
    Keywords: Key words Olfactory receptors ; Multigene families ; Pseudogenes ; Vertebrate species ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract In species representing different levels of vertebrate evolution, olfactory receptor genes have been identified by molecular cloning techniques. Comparing the deduced amino-acid sequences revealed that the olfactory receptor gene family of Rana esculenta resembles that of Xenopus laevis, indicating that amphibians in general may comprise two classes of olfactory receptors. Whereas teleost fish, including the goldfish Carassius auratus, possess only class I receptors, the `living fossil' Latimeria chalumnae is endowed with both receptor classes; interestingly, most of the class II genes turned out to be pseudogenes. Exploring receptor genes in aquatic mammals led to the discovery of a large array of only class II receptor genes in the dolphin Stenella Coeruleoalba; however, all of these genes were found to be non-functional pseudogenes. These results support the notion that class I receptors may be specialized for detecting water-soluble odorants and class II receptors for recognizing volatile odorants. Comparing the structural features of both receptor classes from various species revealed that they differ mainly in their extracellular loop 3, which may contribute to ligand specificity. Comparing the number and diversity of olfactory receptor genes in different species provides insight into the origin and the evolution of this unique gene family.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003590050287
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  • 2
    Electronic Resource
    Electronic Resource
    Evolution on a Smooth Landscape: The Role of Bias (1998)
    Springer
    Journal of statistical physics 90 (1998), S. 191-210 
    Details
    ISSN: 1572-9613
    Keywords: Evolution ; birth/death processes ; mean-field ; population dynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The role of mutational bias in evolution on a smooth landscape is investigated. We consider both a finite-length genome where the bias increases linearly with the fitness, and an infinite genome with a fixed bias. We present simulations of finite populations in a waiting time model, showing both the nonequilibrium dynamics and the equilibrium fitness distributions that are reached. We compute the equilibrium analytically in several cases, using approximate direct solution of the master equations and truncated hierarchies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1023203818384
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  • 3
    Electronic Resource
    Electronic Resource
    Of mites and zen: expression studies in a chelicerate arthropod confirm zen is a divergent Hox gene (1998)
    Springer
    Development genes and evolution 208 (1998), S. 591-594 
    Details
    ISSN: 1432-041X
    Keywords: Key words Arthropod ; Hox ; Evolution ; Development ; Chelicerate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  We have cloned, from an oribatid mite, a gene homologous to the zerknült (zen) genes of insects and the Hox 3 genes of vertebrates. Hox genes specify cell fates in specific regions of the body in all metazoans studied and are expressed in antero-posteriorly restricted regions of the embryo. This is true of the vertebrate Hox 3 but not of the zen genes, the insect homologs, and it has been proposed that the zen genes have lost their Hox-like function in the ancestor of the insects. We studied expression of a mite Hox 3/zen homolog and found that it is expressed in a discrete antero-posterior region of the body with an anterior boundary coinciding with that of the chelicerate homolog of the Drosophila Hox gene, proboscipedia, and propose that its loss of Hox function in insects is due to functional redundancy due to this overlap with another Hox gene.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004270050219
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  • 4
    Electronic Resource
    Electronic Resource
    The PBC domain contains a MEINOX domain: Coevolution of Hox and TALE homeobox genes? (1998)
    Springer
    Development genes and evolution 208 (1998), S. 113-116 
    Details
    ISSN: 1432-041X
    Keywords: Key words TALE homeobox gene ; MEINOX domain ; Hox cluster ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  A recent survey of TALE superclass homeobox genes revealed a new domain upstream of the homeodomain that is conserved between the plant KNOX genes and the animal MEIS genes. At the same time, another paper identified the Drosophila gene homothorax (hth) as a homologue of the vertebrate MEIS genes, which prompted a reexamination of the sequences of the MEIS, KNOX (collectively named MEINOX) and PBC domains. Similarity of the complete MEINOX domain was found within the PBC domain. This suggests that the PBC class genes were also derived from the ancient MEINOX genes. Recently, it has been shown that the MEIS genes can interact with the Abd-B genes, whilst previous results have shown that the PBC genes interact with anterior Hox genes. This leads to the hypothesis that the duplication of an ancestral MEINOX gene into the PBC and MEIS genes happened at a point in time when the first two Hox cluster genes, an anterior one and a posterior one, emerged, and that subsequently these gene classes coevolved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004270050161
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  • 5
    Electronic Resource
    Electronic Resource
    An amphioxus snail gene: Expression in paraxial mesoderm and neural plate suggests a conserved role in patterning the chordate embryo (1998)
    Springer
    Development genes and evolution 208 (1998), S. 569-577 
    Details
    ISSN: 1432-041X
    Keywords: Key words Amphioxus ; Snail ; Neural crest ; Evolution ; Chordate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Homologs of the Drosophila snail gene have been characterized in several vertebrates. In addition to being expressed in mesoderm during gastrulation, vertebrate snail genes are also expressed in presumptive neural crest and/or its derivatives. Given that neural crest is unique to vertebrates and is considered to be of fundamental importance in their evolution, we have cloned and characterized the expression of a snail gene from amphioxus, a cephalochordate widely accepted as the sister group of the vertebrates. We show that, at the amino acid sequence level, the amphioxus snail gene is a clear phylogenetic outgroup to all the characterized vertebrate snail genes. During embryogenesis snail expression initially becomes restricted to the paraxial or presomitic mesoderm of amphioxus. Later, snail is expressed at high levels in the lateral neural plate, where it persists during neurulation. Our results indicate that an ancestral function of snail genes in the lineage leading to vertebrates is to define the paraxial mesoderm. Furthermore, our results indicate that a cell population homologous to the vertebrate neural crest may be present in amphioxus, thus providing an important link in the evolution of this key vertebrate tissue.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004270050216
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  • 6
    Electronic Resource
    Electronic Resource
    Characterization of the zebrafish tbx16 gene and evolution of the vertebrate T-box family (1998)
    Springer
    Development genes and evolution 208 (1998), S. 94-99 
    Details
    ISSN: 1432-041X
    Keywords: Key words T-box ; Evolution ; Zebrafish ; Paraxial mesoderm ; Tail bud
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  We report on a new zebrafish T-box-containing gene, tbx16. It encodes a message that is first detected throughout the blastoderm soon after the initiation of zygotic gene expression. Following gastrulation, expression becomes restricted to paraxial mesoderm and later primarily to the developing tail bud. To gain an evolutionary prospective on the potential function of this gene, we have analyzed its phylogenetic relationships to known T-box genes from other species. Zebrafish tbx16 is likely orthologous to the chicken Tbx6L and Xenopus Xombi/Antipodean/Brat/VegT genes. Our analysis also shows that zebrafish tbx6 and mouse Tbx6 genes are paralogous to zebrafish tbx16. We present evidence which argues, that despite the same name and similar expression, zebrafish tbx6 and mouse Tbx6 genes are not orthologous to each other but instead represent relatively distant paralogs. The expression patterns of all genes are discussed in the light of their evolutionary relationships.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004270050158
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  • 7
    Electronic Resource
    Electronic Resource
    Association of developmental regulatory genes with the development of different molar tooth shapes in two species of rodents (1998)
    Springer
    Development genes and evolution 208 (1998), S. 477-486 
    Details
    ISSN: 1432-041X
    Keywords: Key words Tooth morphogenesis ; Evolution ; Mouse ; Microtus rossiaemeridionalis ; Enamel knot
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  While the evolutionary history of mammalian tooth shapes is well documented in the fossil record, the developmental basis of their tooth shape evolution is unknown. We investigated the expression patterns of eight developmental regulatory genes in two species of rodents with different molar morphologies (mouse, Mus musculus and sibling vole, Microtus rossiaemeridionalis). The genes Bmp-2, Bmp-4, Fgf-4 and Shh encode signal molecules, Lef-1, Msx-1 and Msx-2, are transcription factors and p21 CIP1/WAF1 participates in the regulation of cell cycle. These genes are all known to be associated with developmental regulation in mouse molars. In this paper we show that the antisense mRNA probes made from mouse cDNA cross-hybridized with vole tissue. The comparisons of gene expression patterns and morphologies suggest that similar molecular cascades are used in the early budding of tooth germs, in the initiation of tooth crown base formation, and in the initiation of each cusp’s development. Furthermore, the co-localization of several genes indicate that epithelial signalling centres function at the three stages of morphogenesis. The earliest signalling centre in the early budding epithelium has not been reported before, but the latter signalling centres, the primary and the secondary enamel knots, have been studied in mouse. The appearance of species-specific tooth shapes was manifested by the regulatory molecules expressed in the secondary enamel knots at the areas of future cusp tips, whilst the mesenchymal gene expression patterns had a buccal bias without similar species-specific associations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004270050206
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  • 8
    Electronic Resource
    Electronic Resource
    A toxin homology domain in an astacin-like metalloproteinase of the jellyfish Podocoryne carnea with a dual role in digestion and development (1998)
    Springer
    Development genes and evolution 208 (1998), S. 259-266 
    Details
    ISSN: 1432-041X
    Keywords: Key words Astacin ; Metalloproteinase ; Toxin ; Cnidaria ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Metalloproteinases of the astacin family such as tolloid play major roles in animal morphogenesis. Cnidarians are thought to be evolutionary simple organisms and, therefore, a metalloproteinase from the marine hydrozoan Podocoryne carnea was analysed to evaluate the role of this conserved gene familiy at the base of animal evolution. Surprisingly, the proteinase domain of Podocornyne PMP1 is more similar to human meprin than to HMP1 from another hydrozoan, the freshwater polyp Hydra vulgaris. However, PMP1 and HMP1 both contain a small C-terminal domain with six cysteines that distinguishes them from other astacin-like molecules. Similar domains have been described only recently from sea anemone toxins specific for potassium channels. This toxin homology (Tox1) domain is clearly distinct from epidermal growth factor (EGF)-like domains or other cysteine-rich modules and terminates with the characteristic pattern CXXXCXXC with three out of six cysteines in the last eight residues of the protein. PMP1 is transiently expressed at various sites of morphogenetic activity during medusa bud development. In the adult medusa, however, expression is concentrated to the manubrium, the feeding organ, where the PMP1 gene is highly induced upon feeding. These disparate expression patterns suggest a dual role of PMP1 comparable to tolloid in development and, like astacin in the crayfish, also for food digestion. The Tox1 domain of PMP1 could serve as a toxin to keep the pray paralysed after ingestion, but as a sequence module such Tox1 domains with six cysteines are neither restricted to cnidarians nor to toxins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004270050180
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  • 9
    Electronic Resource
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    β 2 -microglobulin in neotropical primates (Platyrrhini) (1998)
    Springer
    Immunogenetics 48 (1998), S. 133-140 
    Details
    ISSN: 1432-1211
    Keywords: Key words β2-microglobulin ; Primates ; Evolution ; Diversity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Nucleotide sequences for the three exons of the β2-microglobulin (β2m) gene (B2m) were determined for 135 animals representing 37 species and all 16 genera of neotropical primates (Platyrrhini). Twenty-eight different nucleotide sequences, encoding for 26 different proteins, were obtained. In comparison with those of other primate species, the β2-microglobulins of the Platyrrhini form a distinct clade. Individual genera of neotropical primates have distinctive B2m sequences, but within a genera species can have either the same or different B2m sequences. B2m polymorphism was found within three of the species sampled: Callicebus personatus, Saguinus midas, and Aotus azarae. Of these only the polymorphism in A. azarae has an effect upon the mature, functional β2m protein: residue 4 being either alanine or threonine. The A. azarae B2m allele encoding alanine at position 4 is shared with another species of Aotus (A. infulatus). In pairwise comparison the mature β2m proteins of neotropical primates differ by 1–9 amino acid substitutions which can occur at 18 positions within the sequence. The substitutions are distributed throughout the primary structure but are more commonly found in loops rather than β strands of the tertiary structure. Of 17 residues of β2m which hydrogen-bond with the class I heavy chain in human MHC class I molecules, 13 are conserved in the neotropical primates. The overall pattern of sequence variation in the B2m genes of the Platyrrhini is consistent with an evolution by successive selectively neutral events.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002510050413
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  • 10
    Electronic Resource
    Electronic Resource
    Distinct patterns of IgH structure and organization in a divergent lineage of chrondrichthyan fishes (1998)
    Springer
    Immunogenetics 47 (1998), S. 234-245 
    Details
    ISSN: 1432-1211
    Keywords: Key words MHC class I ; Chimpanzee ; Inter-species allele ; Intron ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Immunoglobulin heavy chain (IgH) genes in representative chondrichthyan fishes (sharks and skates) consist of independently functioning clusters, containing separate variable (V H ), diversity (D H ), and joining (J H ) region elements and constant (C H ) region exons. IgH loci have been characterized in Hydrolagus colliei (spotted ratfish), a modern representative of a major independent chondrichthyan lineage. Three distinct families of IgH gene clusters were identified. The most numerous genes consist of unjoined V H -D 1 -D 2 -J H segments that correspond to the most abundant Hydrolagus spleen (cDNA) transcripts which apparently arise from a diversified gene family. In the second cluster type, V H , D H , and J H segments are germline-joined, whereas the C H exons exhibit typical organization. This gene type is found in only a few copies per haploid genome and both transmembrane and secretory transcripts have been identified. A third cluster type has been identified that consists of unjoined V H elements but lacks a typical C H 1 exon, which is substituted with a second C H 2-like exon. Transcripts from this third cluster type also appear to derive from a diversified gene family. Genomic D regions of the two unjoined clone types exhibit structural differences that are consistent with incorporation of recombination machinery-mediated events. Genomic library screening indicates that 90% of V H + clones are truncated, nearly identical pseudogenes (lacking J H and C H ). These studies demonstrate an early phylogenetic origin for the cluster type of gene organization and document extensive organizational diversification within an apparent single class of IgH genes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002510050353
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  • 11
    Electronic Resource
    Electronic Resource
    Evolutionary stability of the immunoglobulin heavy chain variable region gene families in teleost (1998)
    Springer
    Immunogenetics 47 (1998), S. 272-277 
    Details
    ISSN: 1432-1211
    Keywords: Key words Immunoglobulin ; Evolution ; Arctic charr ; Rainbow trout ; VH gene familiy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  A comparison between related species would allow us to study the evolutionary changes in complex gene families. To investigate the evolution of immunoglobulin VH gene families in lower vertebrates, we compared cDNA VH clones from two related teleost fish species, Arctic charr (Salvelinus alpinus) and rainbow trout (Oncorhynchus mykiss), which are separated from their common ancestor by 12–20 million years (MY). The results showed that randomly isolated charr VH genes could be closely grouped to known VH genes of rainbow trout, suggesting that the VH family structure is stable during 12–20 MY and that the total number of VH families changes only gradually over a longer period. This finding also led us to define eight VH gene families of Arctic charr, designated Salalp VH I, VH II, and so on. The presence of species-specific amino acids suggests that non-reciprocal genetic exchanges (e.g., gene duplication) play an important role in shaping the evolution of the V gene family.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002510050357
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  • 12
    Electronic Resource
    Electronic Resource
    Structural differences between the repertoires of mouse and human germline genes and their evolutionary implications (1998)
    Springer
    Immunogenetics 47 (1998), S. 355-363 
    Details
    ISSN: 1432-1211
    Keywords: Key words Mice ; Immunoglobulins ; Canonical ; structures Igk-V ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Although human and mouse antibodies are similar when one considers their diversification strategies, they differ in the extent to which kappa and lambda light chains are present in their respective variable light chain repertoires. While the Igk-V germline genes are preponderant in mice (95% or more), they comprise only 60% in humans. This may account for differences in the structural repertoire encoded in the Igk-V germline genes of these species. However, this subject has not been properly investigated, partially because a systematic structural characterization of the mouse Igk-V germline genes has not been undertaken. In the present study we compiled all available information on mouse Igk-V germline genes to characterize their structural repertoire. As expected, comparison with the structural repertoire of human Igk-V germline genes indicates differences. The most interesting is that the mouse Igk-V germline gene repertoire is more diverse in structural terms than its human counterpart: the mouse encodes seven canonical structure classes (combination of canonical structures in L1 and L3). In contrast, the human encodes only four. Analysis of the evolutionary relationships of human and mouse Igk-V germline genes led us to propose that the difference reflects a strategy of mice to compensate for the small lambda chain contribution to the repertoire of their variable light chains.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002510050370
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  • 13
    Electronic Resource
    Electronic Resource
    BAC/YAC contigs from the H2-M region of mouse Chr 17 define gene order as Znf173-Tctex5-Mog-D17Tu42-M3-M2 (1998)
    Springer
    Immunogenetics 47 (1998), S. 371-380 
    Details
    ISSN: 1432-1211
    Keywords: Key words Major histocompatibility complex (MHC) ; Sequence tagged sites (STS) ; Physical mapping ; Evolution ; HLA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  A yeast artificial chromosome (YAC) contig from the C57BL/6 (H2 b ) mouse was created from the major histocompatibility complex (Mhc, H2 in mouse) class Ib subregion, H2-M. It spans approximately 1.2 megabase (Mb) pairs and unites the previous 〉1.5-Mb YAC contigs (Jones et al. 1995) into a single contig, which includes 21 Mhc class I genes distal to H2-T1. A bacterial artificial chromosome (BAC) contig from the 129 (H2 bc ) mouse, spanning approximately 600 kilobases, was also built from Znf173 (Afp, a gene for acid finger protein), through Tctex5 (t-complex testis expressed-5) and Mog (myelin oligodendrocyte glycoprotein), to H2-M2. Twenty-four sequence-tagged site (STS) markers were newly developed, and 35 markers were mapped in the YAC/BAC contigs, which define the marker order as Cen –Znf173–Tctex5 – Mog–D17Tu42–D17Mit232–H2-M3–D17Leh525–H2-M2– Tel. The gene order of Znf173 – Tctex5 – Mog – D17Tu42 is conserved between mouse and human, showing that the middle H2-M region corresponds to the subregion of the human Mhc surrounding HLA-A.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002510050372
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  • 14
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    Isolation and molecular characterization of the rat MR1 homologue, a non-MHC-linked class I-related gene (1998)
    Springer
    Immunogenetics 47 (1998), S. 477-482 
    Details
    ISSN: 1432-1211
    Keywords: Key words Rat ; Major histocompatibility complex class I ; Mr1 ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  We isolated and analyzed a new rat gene which is homologous to the recently described human major histocompatibility complex class I-related gene MR1. The deduced amino acid sequence of the rat Mr1 gene shows conserved cysteine residues typical of class I genes as well as conserved β2-microglobulin and CD8 contact sites. Analysis of partial DNA sequences and restriction fragment length polymorphism patterns of several inbred rat strains indicate that Mr1 is not polymorphic. Mr1 is a single-copy gene, which could be mapped to rat chromosome 13 by co-segregation analysis of Mr1 and a microsatellite marker in the renin (Ren) gene in double-backcross hybrids. The recombination frequency between both genes was determined to be 14.7% (4.9–31.1, 95% confidence limits). Expression analysis revealed various Mr1 transcripts in each organ tested and occurrence of alternative splicing.
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    URL: http://dx.doi.org/10.1007/s002510050385
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  • 15
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    DNA sequence and structure of the mouse RING3 gene: identification of variant RING3 transcripts (1998)
    Springer
    Immunogenetics 48 (1998), S. 82-86 
    Details
    ISSN: 1432-1211
    Keywords: Key words MHC ; H2 ; Kinases ; Alternative splicing ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002510050406
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  • 16
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    Linkage of RXRB-like genes to class I and not to class II Mhc genes in the zebrafish (1998)
    Springer
    Immunogenetics 48 (1998), S. 141-143 
    Details
    ISSN: 1432-1211
    Keywords: Key words Major histocompatibility complex (Uhc) ; Retinoid receptor genes ; Evolution ; Linkage ; Zebrafish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002510050414
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  • 17
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    Multi-level evolution in population games (1998)
    Springer
    International journal of game theory 27 (1998), S. 21-35 
    Details
    ISSN: 1432-1270
    Keywords: Evolution ; games ; multilevel ; group selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract In this paper, we analyze a generalization of the evolutionary model of Kandori, Mailath, & Rob (1993) where the population is partitioned into groups and evolution takes place “in parallel” at the following two levels: (i) within groups, at the lower level; among groups, at the higher one. Unlike in their context, efficiency considerations always overcome those of risk-dominance in the process of selecting the long-run equilibrium. This provides an explicitly dynamic basis for a conclusion reminiscent of those put forward in the biological literature by the so-called theories group selection. From a normative viewpoint, it suggests the potential importance of “decentralization”, here understood as local and independent interaction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01243192
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  • 18
    Electronic Resource
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    Ig heavy chain of the sturgeon Acipenser baeri : cDNA sequence and diversity (1998)
    Springer
    Immunogenetics 48 (1998), S. 372-382 
    Details
    ISSN: 1432-1211
    Keywords: Key words Immunoglobulin ; Heavy chain ; VH gene ; Diversity ; Evolution ; Sturgeon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  To investigate the gene organization of the IGH locus, and the VH diversity of the Siberian sturgeon, a cDNA library was constructed and screened with VH-specific probes from two holostean fish. Isolated clones were analyzed and domain-specific probes used in rescreening of the library, Southern blot analysis, and northern blots. It was concluded that the Siberian sturgeon has one IGH locus with a translocon type of organization. Two allelic variants of the mu gene were found, with identities ranging from 80 to 100% for the different domains (highest for CH4 and lowest for CH2). Sturgeon CH sequences are most closely related to those of holostean fish. There are three distinct VH families, VHI grouping with mammalian clan III, VHII grouping with the teleost clan, and VHIII grouping with the archaic clan. The variability of the CDR 3 region is substantial, and we identified a number of conserved motifs in the D segment. Further, we deduced that there are at least nine different JH segments in the locus, contributing to the antibody repertoire of the sturgeon. The variable segments of the three families can be associated with any of the D or JH segments in the rearrangement. Sturgeon, in addition to the random rearrangement of VH, D, and JH segments, have exonuclease activity, and an introduction of N and probably P nucleotides at the site of rearrangement.
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    URL: http://dx.doi.org/10.1007/s002510050448
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  • 19
    Electronic Resource
    Electronic Resource
    A hypothesis on the evolution of isoprenoid emission by oaks based on the correlation between emission type and Quercus taxonomy (1998)
    Springer
    Oecologia 115 (1998), S. 302-305 
    Details
    ISSN: 1432-1939
    Keywords: Key words Chemo-taxonomy ; Isoprenoid emission ; Evolution ; Quercus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We show that Mediterranean oaks that emit isoprene, monoterpenes or no isoprenoids belong to different subgenera as indicated by morpho-taxonomy and molecular genetics. On the other hand, oaks from North America and Asia that are taxonomically similar to the Mediterranean monoterpene emitter Q. ilex emit isoprene only. We surmise that isoprene emission is a genetic character which evolved ancestrally in the oak genus since this is the prevalent emission type in oaks widespread around the world and adapted to different environments. This ancestral character may have been either lost or modified in more recent clades such as those originating the Mediterranean oaks. If our hypothesis is correct then the taxonomy of European oaks is validated by this independent trait. Isoprenoid emission could serve as a chemo-taxonomical marker and could be used to reconstruct the phylogeny of oaks in association with molecular markers.
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    URL: http://dx.doi.org/10.1007/s004420050520
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  • 20
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    Sequence similarities of glyceraldehyde-3-phosphate dehydrogenases, phosphoglycerate kinases, and pyruvate kinases are species optimal temperature-dependent (1998)
    Springer
    European biophysics journal 27 (1998), S. 409-410 
    Details
    ISSN: 1432-1017
    Keywords: Key words Sequence similarity ; Glyceraldehyde-3-phosphate dehydrogenase ; Phosphoglycerate kinase ; Pyruvate kinase ; Evolution ; Phylogeny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Data are presented that suggest enzyme sequence similarities among species are not solely a function of their evolutionary relationship. It is demonstrated that sequence similarities of glyceraldehyde-3-phosphate dehydrogenases, phosphoglycerate kinases, and pyruvate kinases from yeast, bacteria, mammals and a bird possess a significant species optimal thriving temperature dependence that crosses through conventional phylogenetic divisions. It is therefore suggested that species which are distantly related evolutionarily may possess some degree of enzyme sequence similarity if they happen to thrive at near the same optimal temperature; conversely, organisms which are closely related evolutionarily but function at radically different temperatures will possess a sequence dissimilarity that may mask the close relatedness.
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    URL: http://dx.doi.org/10.1007/s002490050148
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    Correlation between auditory sensitivity and vocalization in anabantoid fishes (1998)
    Springer
    Journal of comparative physiology 182 (1998), S. 737-746 
    Details
    ISSN: 1432-1351
    Keywords: Key words Auditory sensitivity ; Sound spectra ; ABR ; Evolution ; Communication
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Several anabantoid species produce broad-band sounds with high-pitched dominant frequencies (0.8–2.5 kHz), which contrast with generally low-frequency hearing abilities in (perciform) fishes. Utilizing a recently developed auditory brainstem response recording-technique, auditory sensitivities of the gouramis Trichopsis vittata, T. pumila, Colisa lalia, Macropodus opercularis and Trichogaster trichopterus were investigated and compared with the sound characteristics of the respective species. All five species exhibited enhanced sound-detecting abilities and perceived tone bursts up to 5 kHz, which qualifies this group as hearing specialists. All fishes possessed a high-frequency sensitivity maximum between 800 Hz and 1500 Hz. Lowest hearing thresholds were found in T. trichopterus (76 dB re 1 μPa at 800 Hz). Dominant frequencies of sounds correspond with the best hearing bandwidth in T. vittata (1–2 kHz) and C. lalia (0.8–1 kHz). In the smallest species, T. pumila, dominant frequencies of acoustic signals (1.5–2.5 kHz) do not match lowest thresholds, which were below 1.5 kHz. However, of all species studied, T. pumila had best hearing sensitivity at frequencies above 2 kHz. The association between high-pitched sounds and hearing may be caused by the suprabranchial air-breathing chamber, which, lying close to the hearing and sonic organs, enhances both sound perception and emission at its resonant frequency.
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    URL: http://dx.doi.org/10.1007/s003590050218
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    Differential regulation of a homologous peptidergic neuron in grasshoppers: evolution of a neural circuit (1998)
    Springer
    Journal of comparative physiology 182 (1998), S. 755-765 
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    ISSN: 1432-1351
    Keywords: Key words Acetylcholine ; Evolution ; Histamine ; Homology ; Insect ; Vasopressin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The vasopressin-like immunoreactive (VPLI) neurons of grasshoppers have paired cell bodies in the suboesophageal ganglion and both anterior and posterior running axons. In non-oedipodine grasshopper species (e.g. Schistocerca gregaria), most of their arborisations are distributed in dorsal and lateral neuropil, while in oedipodine species (e.g. Locusta migratoria), the neurons have additional extensive axonal projections in both the optic lobes and proximal portions of the ganglionic peripheral nerves. This study demonstrates that these morphological differences correlate with their physiology. In L. migratoria, VPLI neuron activity is regulated primarily via a spontaneously active interneuron which descends from the brain. This descending interneuron is inhibited by a light-activated brain extraocular photoreceptor. Regulation of VPLI neuron activity by an extraocular photoreceptor is also seen in the other oedipodine grasshopper investigated. In the four non-oedipodines examined (from two subfamilies), we find no extraocular photoreceptor regulation of VPLI neuron activity. Despite this, VPLI neuron in S.␣gregaria does appear to be driven by a descending interneuron homologous to that in L. migratoria. The descending interneuron in both species receives similar mechanosensory input and excites the VPLI neuron via cholinergic synapses. Histamine injection into the medial protocerebrum of both species causes strong inhibition of the descending interneuron. The evolution of the neural circuitry, by which an extraocular photoreceptor comes to regulate the descending interneuron in oedipodine species, is discussed.
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    URL: http://dx.doi.org/10.1007/s003590050220
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    Evidence for recombination as a mechanism for KIR diversification (1998)
    Springer
    Immunogenetics 48 (1998), S. 413-416 
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    ISSN: 1432-1211
    Keywords: Key words KIR ; Natural killer cell ; Recombination ; Gene conversion ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
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    URL: http://dx.doi.org/10.1007/s002510050453
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    A spectrum of equilibration processes in game theory (1998)
    Springer
    Journal of evolutionary economics 8 (1998), S. 67-87 
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    ISSN: 1432-1386
    Keywords: Key words: Bounded rationality ; Cognitive rationality ; Game equilibrium ; Evolution ; Learning ; JEL-classification: B 41; C 73; D 83; D 84
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract. In game theory, four dynamic processes converging towards an equilibrium are distinguished and ordered by way of agents' decreasing cognitive capacities. In the eductive process, each player has enough information to simulate perfectly the others' behavior and gets immediately to the equilibrium. In epistemic learning, each player updates his beliefs about others' future strategies, with regard to their sequentially observed actions. In behavioral learning, each player modifies his own strategies according to the observed payoffs obtained from his past actions. In the evolutionary process, each agent has a fixed strategy and reproduces in proportion to the utilities obtained through stochastic interactions. All along the spectrum, longer term dynamics makes up for weaker rationality, and physical relations substitute for mental interactions. Convergence, if any, is towards an always stronger equilibrium notion and selection of an equilibrium state becomes more sensitive to context and history. The processes can be mixed if associated to different periods, agents or mechanisms and deepened if obtained by formal reasoning principles.
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    URL: http://dx.doi.org/10.1007/s001910050056
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    Classification of African plantain landraces and banana cultivars using a phenotypic distance index of quantitative descriptors (1998)
    Springer
    Theoretical and applied genetics 96 (1998), S. 904-911 
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    ISSN: 1432-2242
    Keywords: Key words Musa ; Core collection ; Duplicates ; Evolution ; Variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Proper classification and establishment of relationships between and within Musa taxonomic clusters will be important tools for the genetic improvement of plantain and banana. This paper assesses the value of a phenotypic diversity index, based on 16 quantitative descriptors, for germplasm clustering and for identification of duplicates among 92 triploid plantain and banana accessions. Data were recorded during the plant and ratoon crops at Onne, a humid forest location in southeastern Nigeria. The phenotypic distance matrix was developed by calculating the average difference between each pair of accessions for all quantitative descriptors. Significant differences were observed for this phenotypic distance index between Musa taxonomic clusters. The between-cluster variance was larger (0.001779) than the within-cluster variance (0.001380). Wright’s φFS, which measures the overall diversity, was 0.5663. This value suggested little gene flow among triploid taxonomic clusters via pollen, which explains the higher population differentiation exhibited by this vegetatively propagated crop with very low male fertility. The results also suggested that variation observed within each Musa taxonomic cluster arose from mutations accumulated throughout the history of cultivation of this crop. Some putative duplicates based on qualitative descriptors were not regarded as the same accession according to the phenotypic diversity index based on quantitative descriptors. Hence, gene-bank curators should assess quantitative descriptors for the identification of duplicate accessions in Musa.
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    URL: http://dx.doi.org/10.1007/s001220050818
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    Evolutionary relationship of plant catalase genes inferred from exon-intron structures: isozyme divergence after the separation of monocots and dicots (1998)
    Springer
    Theoretical and applied genetics 97 (1998), S. 9-19 
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    ISSN: 1432-2242
    Keywords: Key words Catalase ; Rice ; Gene structure ; Evolution ; Transposon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In order to understand the molecular evolution of catalase genes in higher plants, we compared the exon-intron structures of 12 genomic sequences from six plant species. It was assumed that the putative single primordial catalase gene had seven introns, because only those catalase genes having this structure are found in the monocotyledonae and dicotyledonae classes. After the evolutionary divergence of monocots from dicots, consecutive duplication of the primordial gene followed by the differential loss of introns occurred in each class to form three (or possibly four in dicots) diverse isozyme genes. In monocots, three ancestral isozyme genes were formed before the divergence of ancestral rice and maize. One of the rice genes, CatA, has an entirely new short intron which was not found in any other plant catalase gene examined. We have investigated the existence of the intron in the CatA homolog in other rice species by polymerase chain reaction (PCR) analysis. One major PCR product was found with the genomic DNAs from O. sativa (indica and japonica types), O. rufipogon and O. glaberrima. DNAs from several accessions of O. longistaminata showed variation in both the number and size of the DNA fragments amplified. PCR analyses and sequencing of the PCR products revealed that there are several CatA homologs having different sequences in some accessions of O. longistaminata. We have extended our study to other species in the Poaceae. The results suggest that the gain of the intron, most likely by insertion of a retroposon, took place in the ancestral genome of rice after its evolutionary divergence from other ancestral cereals such as barley, wheat and oat.
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    URL: http://dx.doi.org/10.1007/s001220050861
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    The structure of the Aegilops tauschii genepool and the evolution of hexaploid wheat (1998)
    Springer
    Theoretical and applied genetics 97 (1998), S. 657-670 
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    ISSN: 1432-2242
    Keywords: Key words Triticum aestivum ; Phylogeny ; Genetic distance ; Genome ; Introgression ; Allopolyploidy ; RFLP ; Glutenin ; rRNA ; Non-transcribed spacers ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Polymorphism in the lengths of restriction fragments at 53 single-copy loci, the rRNA locus Nor3, and the high-molecular-weight glutenin locus Glu1 was investigated in the D genome of hexaploid Triticum aestivum and that of Aegilops tauschii, the source of the T. aestivum D genome. The distribution of genetic variation in Ae. tauschii suggests gene flow between Ae. tauschii ssp. strangulata and ssp. tauschii in Iran but less in Transcaucasia. The “strangulata” genepool is wider than it appears on the basis of morphology and includes ssp. strangulata in Transcaucasia and southeastern (SE) Caspian Iran and ssp. tauschii in north-central Iran and southwestern (SW) Caspian Iran. In the latter region, Ae. tauschii morphological varieties ‘meyeri’ and ‘typica’ are equidistant to ssp. strangulata in Transcaucasia, and both belong to the “strangulata” genepool. A model of the evolution of Ae. tauschii is presented. On the geographic region basis, the D genomes of all investigated forms of T. aestivum are most closely related to the “strangulata” genepool in Transcaucasia, Armenia in particular, and SW Caspian Iran. It is suggested that the principal area of the origin of T. aestivum is Armenia, but the SW coastal area of the Caspian Sea and a corridor between the two areas may have played a role as well. Little genetic differentiation was found among the D genomes of all investigated free-threshing and hulled forms of T. aestivum, and all appear to share a single D-genome genepool, in spite of the fact that several Ae. tauschii parents were involved in the evolution of T. aestivum.
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    URL: http://dx.doi.org/10.1007/s001220050942
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    Echolocation and foraging behavior of the lesser bulldog bat, Noctilio albiventris : preadaptations for piscivory? (1998)
    Springer
    Behavioral ecology and sociobiology 42 (1998), S. 305-319 
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    ISSN: 1432-0762
    Keywords: Key words Bats ; Echolocation ; Foraging ; Evolution ; Piscivory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We studied variability in foraging behavior of Noctilio albiventris (Chiroptera: Noctilionidae) in Costa Rica and Panamá and related it to properties of its echolocation behavior. N. albiventris searches for prey in high (〉20 cm) or low (〈20 cm) search flight, mostly over water. It captures insects in mid-air (aerial captures) and from the water surface (pointed dip). We once observed an individual dragging its feet through the water (directed random rake). In search flight, N. albiventris emits groups of echolocation signals (duration 10–11 ms) containing mixed signals with constant-frequency (CF) and frequency-modulated (FM) components, or pure CF signals. Sometimes, mostly over land, it produces long FM signals (duration 15–21 ms). When N. albiventris approaches prey in a pointed dip or in aerial captures, pulse duration and pulse interval are reduced, the CF component is eliminated, and a terminal phase with short FM signals (duration 2 ms) at high repetition rates (150–170 Hz) is emitted. Except for the last pulses in the terminal phase N. albiventris avoids overlap between emitted signals and echoes returning from prey. During rakes, echolocation behavior is similar to that in high search flight. We compare N. albiventris with its larger congener, N. leporinus, and discuss behavioral and morphological specializations that can be interpreted as preadaptations favoring the evolution of piscivory as seen in N. leporinus. Prominent among these specializations are the CF components of the echolocation signals which allow detection and evaluation of fluttering prey amidst clutter-echoes, high variability in foraging strategy and the associated echolocation behavior, as well as morphological specializations such as enlarged feet for capturing prey from the water surface.
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    URL: http://dx.doi.org/10.1007/s002650050443
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    Polymorphism of the S -locus glycoprotein gene (SLG ) and the S -locus related gene (SLR1 ) in Raphanus sativus L. and self-incompatible ornamental plants in the Brassicaceae (1998)
    Springer
    Molecular genetics and genomics 258 (1998), S. 397-403 
    Details
    ISSN: 1617-4623
    Keywords: Key words Stigma glycoprotein ; Orychophragmus violaceus ; Cheiranthus cheiri ; Iberis amara ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The S-locus glycoprotein gene, SLG, which participates in the pollen-stigma interaction of self-incompatibility, and its unlinked homologue, SLR1, were analyzed in Raphanus sativus and three self-incompatible ornamental plants in the Brassicaceae. Among twenty-nine inbred lines of R. sativus, eighteen S haplotypes were identified on the basis of DNA polymorphisms detected by genomic Southern analysis using Brassica SLG probes. DNA fragments of SLG alleles specifically amplified from eight S haplotypes by PCR with class I SLG-specific primers showed different profiles following polyacrylamide gel electrophoresis, after digestion with a restriction endonuclease. The nucleotide sequences of the DNA fragments of these eight R. sativus SLG alleles were determined. Degrees of similarity of the nucleotide sequences to a Brassica SLG (S  6 SLG) ranged from 85.6% to 91.9%. Amino acid sequences deduced from these had the twelve conserved cysteine residues and the three hypervariable regions characteristic of Brassica SLGs. Phylogenetic analysis of the SLG sequences from Raphanus and Brassica revealed that the Raphanus SLGs did not form an independent cluster, but were dispersed in the tree, clustering together with Brassica SLGs. These results suggest that diversification of the SLG alleles of Raphanus and Brassica occurred before differentiation of these genera. Although SLR1 sequences from Orychophragmus violaceus were shown to be relatively closely related to Brassica and Raphanus SLR1 sequences, DNA fragments that are highly homologous to the Brassica SLG were not detected in this species. Two other ornamental plants in the Brassicaceae, which are related more distantly to Brassica than Orychophragmus, also lacked sequences highly homologous to Brassica SLG genes. The evolution of self-incompatibility in the Brassicaceae is discussed.
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    URL: http://dx.doi.org/10.1007/s004380050747
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    Pollen morphology and functional dioecy inSolanum (Solanaceae) (1998)
    Springer
    Plant systematics and evolution 210 (1998), S. 113-139 
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    ISSN: 1615-6110
    Keywords: Solanaceae ; Solanum ; Evolution ; male sterility ; breeding system ; dioecy ; inaperturate pollen ; pollen development ; palynology ; plant reproduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Dioecy has evolved independently several times in the large, mostly tropical genusSolanum. In all cases of dioecy inSolanum functionally male flowers have normal anthers, normal pollen and reduced stigmas while functionally female flowers have stigmas and anthers that appear normal but contain non-functional, usually inaperturate pollen. The inaperturate pollen has living cytoplasm, but apparently never germinates and it has been hypothesised that the pollen in these functionally female flowers is retained as a pollinator reward. Pollen morphology is compared in twelve of the thirteen known dioecious species ofSolanum, and some stages in the the development of inaperturate pollen in the anthers of functionally female flowers ofSolanum confertiseriatum of Western Ecuador are examined. Observations on the development and morphology of inaperturate pollen in functionally female flowers ofSolanum are related to hypotheses about the evolution of dioecy in the genus.
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    Evolution of a vision system by genetic algorithm (1998)
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    Artificial life and robotics 2 (1998), S. 179-183 
    Details
    ISSN: 1614-7456
    Keywords: Evolution ; Vision system ; Genetic algorithm ; Neural network ; Artificial life
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract This paper proposes a framework for a genetic algorithm applied to determine and construct an organ, especially the neural network of a virtual creature. The vision system of the creature is a result of genetic evolution, and we are trying to realize this on the computer. We examine how the visual organ of the animal is evolved under a special environment (e.g., the specialized visual organ of an animal to catch a moving insect), and how many variations of neural networks exist. We also think it is possible to generalize the method to an automatic generation of various kinds of visual recognition system by adding various kinds of evolution any directions.
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    URL: http://dx.doi.org/10.1007/BF02471178
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    Three highly divergent subfamilies of the impala transposable element coexist in the genome of the fungus Fusarium oxysporum (1998)
    Springer
    Molecular genetics and genomics 259 (1998), S. 354-362 
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    ISSN: 1617-4623
    Keywords: Key wordsTc1-mariner ; Filamentous fungi ; Fusarium oxysporum ; Transposase ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The transposable element impala is a member of the widespread superfamily of Tc1-mariner transposons, identified in the genome of the plant pathogenic fungus Fusarium oxysporum. This element is present in a low copy number and is actively transposed in the F.␣oxysporum strain F24 that is pathogenic for melons. The structure of the impala family was investigated by cloning and sequencing all the genomic copies. The analysis revealed that this family is composed of full-length and truncated copies. Four copies contained a long open reading frame that could potentially encode a transposase of 340 amino acids. The presence of conserved functional domains (a nuclear localisation signal, a catalytic DDE domain and a DNA-binding domain) suggests that these four copies may be autonomous elements. Sequence comparisons and phylogenetic analysis of the impala copies defined three subfamilies, which differ by a high level of nucleotide polymorphism (around 20%). The coexistence of these divergent subfamilies in the same genome may indicate that the impala family is of ancient origin and/or that it arose by successive horizontal transmission events.
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    The P25 component of Galleria silk (1998)
    Springer
    Molecular genetics and genomics 257 (1998), S. 264-270 
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    ISSN: 1617-4623
    Keywords: Key words Fibroin ; Glycosylation ; DNA sequence ; Evolution ; Silkworm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The water-insoluble core of lepidopteran silk is composed of four major proteins, but only three genes have been identified. This study demonstrates that the 29- and 30-kDa components of Galleria mellonella silk are derived from a single gene designated P25. The gene is expressed exclusively in the posterior section of the silk glands as a 2-kb mRNA, which accumulates in the feeding larvae and declines at molting. The mRNA encodes a peptide of 24 864 Da that exhibits 51% identity with the putative product of the P25 gene of Bombyx. The conservation of several amino acid stretches, including the relative positions of all 8 cysteines in the mature polypeptide, implies that the P25 proteins play similar, and apparently significant roles in silk formation in the two species. A Galleria P25 cDNA yields a peptide of about 25 kDa when translated in vitro; the 29- and 30-kDa forms present in the silk are derived from this primary translation product by differential glycosylation.
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    A tobacco gene encoding a novel basic class II chitinase: a putative ancestor of basic class I and acidic class II chitinase genes (1998)
    Springer
    Molecular genetics and genomics 259 (1998), S. 511-515 
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    ISSN: 1617-4623
    Keywords: Key words Chitinase ; Tobacco ; Transposition ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Various chitinases have been identified in plants and categorized into several groups based on the analysis of their sequences and domains. We have isolated a tobacco gene that encodes a predicted polypeptide consisting of a 20-amino acid N-terminal signal peptide, followed by a 245-amino acid chitinolytic domain. Although the predicted mature protein is basic and shows greater sequence identity to basic class I chitinases (75%) than to acidic class II chitinases (67%), it lacks the N-terminal cysteine-rich domain and the C-terminal vacuolar targeting signal that is diagnostic for class I chitinases. Therefore, this gene appears to encode a novel, basic, class II chitinase, which we have designated NtChia2;B1. Accumulation of Chia2;B1 mRNA was induced in leaves in association with the local-lesion response to tobacco mosaic virus (TMV) infection, and in response to treatment with salicylic acid, but was only slightly induced by treatment with ethephon. Little or no Chia2;B1 mRNA was detected in roots, flowers, and cell-suspension cultures, in which class I chitinase mRNAs accumulate to high concentrations. Sequence comparisons of Chia2;B1 with known tobacco class I and class II chitinase genes suggest that Chia2;B1 might encode an ancestral prototype of the present-day class I and class II isoforms. Possible mechanisms for chitinase gene evolution are discussed.
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    Cytokinesis and nodal anatomy in the charophycean green algaChara zeylanica (1998)
    Springer
    Protoplasma 203 (1998), S. 65-74 
    Details
    ISSN: 1615-6102
    Keywords: Cell plate ; Chara zeylanica ; Cytokinesis ; Evolution ; Meristem ; Plasmodesmata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Cell plate formation inChara zeylanica was compared with recent models of cytokinesis in higher plants in order to gain insight into the evolutionary origin of plant cytokinetic processes. Transmission electron microscopy (TEM) reveals that while cytokinesis inC. zeylanica bears many features in common with that in higher plants, there are significant differences. Unlike that in higher plants, cytokinesis inC. zeylanica begins with a congregation of smooth membrane tubules that are closely associated with endoplasmic reticulum (ER) and Golgi membranes. Mitochondria and other organelles excluded by the phragmoplast in higher plants are present as well. Unlike in higher plants, phragmoplast microtubules persist throughout cytokinesis inC. zeylanica, and the cell plate generally forms across the whole cell at once, though development is patchy, due to small regions developing at different rates; the ends of the plate form last. By identifying aspects of cytokinesis that are different inC. zeylanica and plants, our study indicates which cytokinetic features are more likely to be derived, and which are more likely to be ancestral. In addition, we demonstrated that all nodal cells ofC. zeylanica are interconnected via plasmodesmata, lending support to the idea that, whileChara spp. are generally considered to be filamentous organisms, nodal regions may be thought of as meristemlike tissues.
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    The origin of prokaryotic life and molecular evolution (1998)
    Springer
    World journal of microbiology and biotechnology 14 (1998), S. 607-610 
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    ISSN: 1573-0972
    Keywords: Evolution ; life ; microorganisms ; molecular ; origin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The origin of prokaryotic life is discussed with an emphasis on the self-assembly of early life in a microscale environment where ordered cellular structures and integrated functions evolved from disorder. Early molecular evolution may have been due to both molecular chaos and evolving molecular order.
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    URL: http://dx.doi.org/10.1023/A:1008863326543
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    REVIEW Evolution of phytophagy in trombidiform mites (1998)
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    Experimental and applied acarology 22 (1998), S. 81-100 
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    ISSN: 1572-9702
    Keywords: Evolution ; phytophagy ; trombidiform mites ; gnathosoma ; dispersal ; sex determination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This paper reviews the evolutionary aspects of obligate phytophagy (excluding mycophagy and phycophagy) in the mite suborder Trombidiformes. Phytophagy in the other acariform suborder, Sarcoptiformes, is limited to just a few species, amidst otherwise saprophagous or fungivorous taxa, that attack the living tissues of higher plants. The phylogenetic relationships of lineages that contain taxa of plant-feeding mites are reviewed briefly, to facilitate hypotheses about the number of times that phytophagy has arisen within the Trombidiformes. The relationship between the two most important plant-feeding taxa, the Tetranychoidea and Eriophyoidea, is so distant that their obligate phytophagy represents independent events. Outgroup comparisons allow an estimate of the relative ages when phytophagy arose. This background facilitates analyses of the evolutionary patterns of attributes relevant to phytophagy as a way of life. Styliform modifications of chelate chelicerae for predation or fungivory were fundamental pre-adaptations for effective phytophagy. Dispersal among the major lineages of phytophagous mites seems generally passive, with little evidence of phoretic behaviour. Continued individual mobility seems to be needed during ontogeny and adulthood, such that no scale-like or sac-like instars have arisen. Trends towards physogastric reproduction and ovoviviparity are not evident. Arrhenotokous sex determination predominates among lineages of phytophagous mites. The primary sex ratios are not usually highly female biased. Direct sperm transfer does not seem to have been advantageous or disadvantageous to adaptive radiations of plant-feeding lineages. Adaptive trends towards thelytoky are scattered and do not seem to have played major roles in speciation, diversification or trends towards increasing host specificity in lineages. Alternate asexual and sexual generations and life cycles on different species of hosts, as occur among families of aphid and scale insects, are not known. Among unrelated lineages of trombidiform mites, there appears to have been convergent evolution of attributes, such as those noted above, in response to similar selective pressures for a phytophagous way of life. The patterns of attributes discussed need experimental analysis and detailed documentation to test their accuracy and generality and to understand the selective pressures that have formed them.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006041609774
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  • 38
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    Electronic Resource
    Molecular phylogenetics of the hominoid Y chromosome (1998)
    Springer
    Journal of human genetics 43 (1998), S. 185-186 
    Details
    ISSN: 1435-232X
    Keywords: Key words Chimpanzee ; Gorilla ; Orangutan ; Human Y-chromosome ; Amelogenin gene ; Telomeric sequences ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The Human Y-chromosome plays a central role in sex determination, and is composed of DNA sequences homologous to the Y-chromosome, families of Y-specific repetitive DNA sequences, and single copy sequences. We investigated the chromosomal location of Y-specific DNA sequences, in the chimpanzee (Pan troglodytes), gorilla (Gorilla gorilla), and orangutan (Pongo pygmaeus) by the fluorescence in situ hybridization (FISH) technique. The Yq subtelomeric DNA sequences (DYS427) have been observed to be intact at the presumed loci. Also, the amelogenin gene (AMELY, Yp11.2) revealed sequence homology and positional conservation in the higher primates, except in gorilla where positional divergence was observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100380050066
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