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1.
New species of Pogonophryne (Pisces, Artedidraconidae) from the Bellingshausen Sea, Antarctica 总被引:1,自引:1,他引:0
A new species of notothenioid fish, Pogonophryne bellingshausenensis n. sp., is described from the Bellingshausen Sea, Antarctica. The new species belongs to the dorsally-spotted “mentella”
group of the genus and is characterized by having a short (about 13% SL) mental barbel with a short (about 16% of barbel length),
narrow (barely wider than the stalk), and relatively inconspicuous terminal expansion composed of short, irregular, fingerlike
processes. Compared to most other dorsally-spotted species of Pogonophryne (“barsukovi”, “marmorata”, and “mentella” groups), P. bellingshausenensis has a relatively wide (about 7% SL) interorbital region. An unspotted patch on the median dorsal surface of the head, posterior
to the posttemporal ridges and anterior to the first dorsal fin, has not been observed previously in any dorsally-spotted
species. The holotype was collected at 1,947 m, one of the deepest records for any species of Pogonophryne. A revised key to the ten species of the “mentella” group of Pogonophryne is also provided. 相似文献
2.
Jean-Luc Desseyn Marie-Pierre Buisine Nicole Porchet Jean-Pierre Aubert Pierre Degand Anne Laine 《Journal of molecular evolution》1998,46(1):102-106
The four human mucin genes MUC6, MUC2, MUC5AC, and MUC5B are located at chromosome 11p15.5. It has been demonstrated that the three mucins MUC2, MUC5AC, and MUC5B contain several
Cys-subdomains of 108 amino acid residues. In contrast, little information is available concerning MUC6. These Cys-subdomains
contain 10 cysteine residues that have a highly conserved position. We present here a coherent probable evolutionary history
of this human gene family after comparison of the nucleotide sequences of these Cys-subdomains. The three MUC loci MUC2, MUC5AC, and MUC5B may have evolved from a common ancestral gene by two successive duplications. Moreover, we can postulate that MUC5AC and MUC5B have evolved in a concerted manner, while MUC2 has evolved separately.
Received: 30 January 1997 / Accepted: 17 April 1997 相似文献
3.
Under conditions of a few behavioral tests on rats, we examined the psychotropic activity of novel N-uronoyl derivatives of
amino acids: (i) N-(1,2:3,4-di-O-isopropylidene-α-D-galactopyranuronoyl-β-alanine (DAGU-Ala), (ii) DAGU-glycyl-D,L-glutamic
acid (DAGU-Gly-Glu), and (iii) DAGU-glycyl-glycine (DAGU-Gly-Gly) injected i.p. in a 50 mg/kg dose. In an open-field test,
DAGU-Gly-Glu and DAGU-GLy-Gly showed antistress properties (they decreased the intensity of locomotion, decreased the number
of defecation acts, and intensified the research activity), while DAGU-Ala possessed a psychostimulating effect (intensification
of locomotor and research activity and an increase in the number of defecations). In the “black-and-white chamber” test, only
DAGU-Gly-Gly exerted an anxiolytic effect; it somewhat increased the frequency and duration of emergings of animals from the
dark section and duration of visits to the illuminated section of the chamber. DAGU-GLy-Glu manifested antidepressant properties;
it increased the time of active swimming of the animal in the Porsolt test and decreased the duration of passive “hanging”
of rats in the “suspension by the tail” test.
Neirofiziologiya/Neurophysiology, Vol. 39, No. 1, pp. 52–61, January–February, 2007. 相似文献
4.
A dense accumulation of the phototrophic consortium “Pelochromatium roseum” in a small, eutrophic, freshwater lake (Dagowsee, Brandenburg, Germany) was investigated. Within the chemocline, the number
of epibionts of the consortia represented up to 19% of the total number of bacteria. Per “P. roseum” a mean value of 20 epibionts was determined. Similar to other aquatic habitats, consortia in the Dagowsee were found only
at low light intensities (< 7 μmol quanta m–2 s–1) and low sulfide concentrations (0–100 μM). In dialysis cultures of “P. roseum”, bacterial cells remained in a stable association only when incubated at light intensities between 5 and 10 μmol quanta
m–2 s–1. Intact consortia from natural samples had a buoyant density of 1046.8 kg m–3, which was much higher than that of ambient chemocline water (995.8 kg m–3). Under environmental conditions and without motility, this density difference would result in rapid sedimentation of consortia
toward the lake bottom. Our results indicate that (1) consortia are adapted to a very narrow regime of light intensities and
sulfide concentrations, (2) motility and tactic responses must be of ecological significance for the colonization of the free
water column of lakes, and (3) phototrophic growth of consortia can be explained only by a cycling of sulfur species in the
chemocline, possibly within the consortia themselves.
Received: 27 May 1997 / Accepted: 16 September 1997 相似文献
5.
The pairs of nitrogen fixation genes nifDK and nifEN encode for the α and β subunits of nitrogenase and for the two subunits of the NifNE protein complex, involved in the biosynthesis
of the FeMo cofactor, respectively. Comparative analysis of the amino acid sequences of the four NifD, NifK, NifE, and NifN
in several archaeal and bacterial diazotrophs showed extensive sequence similarity between them, suggesting that their encoding
genes constitute a novel paralogous gene family. We propose a two-step model to reconstruct the possible evolutionary history
of the four genes. Accordingly, an ancestor gene gave rise, by an in-tandem paralogous duplication event followed by divergence,
to an ancestral bicistronic operon; the latter, in turn, underwent a paralogous operon duplication event followed by evolutionary
divergence leading to the ancestors of the present-day nifDK and nifEN operons. Both these paralogous duplication events very likely predated the appearance of the last universal common ancestor.
The possible role of the ancestral gene and operon in nitrogen fixation is also discussed.
Received: 21 June 1999 / Accepted: 1 March 2000 相似文献
6.
Duplications are an important mechanism for the emergence of genetic novelties. Reports on duplicated genes are numerous, and mechanisms for polyploidization or local gene duplication are beginning to be understood. When a local duplication is studied, searches are usually done gene-by-gene, and the size of duplicated segments is not often investigated. Therefore, we do not know if the gene in question has duplicated alone or with other genes, implying that "en bloc" duplications are poorly studied. We propose a method for identification of "en bloc" duplication using mapping, phylogenetic and statistical analyses. We show that two segments present in the major histocompatibility complex (MHC) region of human chromosome 6 have resulted from an "en bloc" duplication that took place between divergence of amniotes and methaterian/eutherian separation. These segments contain members of the same multigenic families, namely olfactory receptors genes, genes encoding proteins containing B30.2 domain, genes encoding proteins containing immunoglobulin V domain and MHC class I genes. We will discuss the fact that olfactory receptors and MHC genes have undergone positive selection, which could have helped in fixation of the surrounding genes. 相似文献
7.
Bernard Labedan Anne Boyen Margot Baetens Daniel Charlier Pingguo Chen Raymond Cunin Virginie Durbeco Nicolas Glansdorff Guy Herve Christianne Legrain Ziyuan Liang Christina Purcarea Martine Roovers Rony Sanchez Thia-Lin Toong Marc Van de Casteele Françoise van Vliet Ying Xu Yuan-Fu Zhang 《Journal of molecular evolution》1999,49(4):461-473
Forty-four sequences of ornithine carbamoyltransferases (OTCases) and 33 sequences of aspartate carbamoyltransferases (ATCases)
representing the three domains of life were multiply aligned and a phylogenetic tree was inferred from this multiple alignment.
The global topology of the composite rooted tree (each enzyme family being used as an outgroup to root the other one) suggests
that present-day genes are derived from paralogous ancestral genes which were already of the same size and argues against
a mechanism of fusion of independent modules. A closer observation of the detailed topology shows that this tree could not
be used to assess the actual order of organismal descent. Indeed, this tree displays a complex topology for many prokaryotic
sequences, with polyphyly for Bacteria in both enzyme trees and for the Archaea in the OTCase tree. Moreover, representatives
of the two prokaryotic Domains are found to be interspersed in various combinations in both enzyme trees. This complexity
may be explained by assuming the occurrence of two subfamilies in the OTCase tree (OTC α and OTC β) and two other ones in
the ATCase tree (ATC I and ATC II). These subfamilies could have arisen from duplication and selective losses of some differentiated
copies during the successive speciations. We suggest that Archaea and Eukaryotes share a common ancestor in which the ancestral
copies giving the present-day ATC II/OTC β combinations were present, whereas Bacteria comprise two classes: one containing
the ATC II/OTC α combination and the other harboring the ATC I/OTC β combination. Moreover, multiple horizontal gene transfers
could have occurred rather recently amongst prokaryotes. Whichever the actual history of carbamoyltransferases, our data suggest
that the last common ancestor to all extant life possessed differentiated copies of genes coding for both carbamoyltransferases,
indicating it as a rather sophisticated organism. 相似文献
8.
T. L. Karaseva B. A. Lobasyuk S. G. Soboleva E. A. Kostenko S. A. Andronati 《Neurophysiology》2000,32(1):8-11
The neuropharmacological profile of 4-phenyl-1-[4-(2-naphtalimido)butyl]-piperazine (PNBP), a compound that possesses a high
affinity for the serotonin receptors of 1A-type (5-HT1A) and lacks an anxiolytic action, has been studied. Intracerebral administration of PNBP to rats through implanted cannulae
into the hippocampal region resulted in no substantial behavioral changes during “open field” and “conflict situation” tests,
as compared with those of control animals. At the same time, the behavioral effects of intraperitoneal administration of 10
mg/kg buspirone were completely abolished if buspirone had been jointly administered with 10 mg/kg PNBP. Moreover, combined
application of 0.3 mg/kg PNBP and 0.3 mg/kg 8-OH-DPAT, an agonist of 5-HT1A receptors, almost completely abolished the components of “serotonin syndrome” (prone position and stamping of the forepaws)
in animals under study. These findings allowed us to conclude that PNBP has the properties of a competitive antagonist of
buspirone and 8-OH-DPAT. 相似文献
9.
S. Pen-Mouratov N. Berg N. Genzer S. Ukabi D. Shargil Y. Steinberger 《Frontiers of Biology in China》2009,4(3):364-375
“Evolution Canyon” is a typical Mediterranean-basin canyon with a summer dry stream at the bottom and large differences in
vegetation cover and solar radiation between the north-facing slope (NFS) and the south-facing slope (SFS). It is known to
act as an abiotic mediator influencing the community structure of soil fauna. The aim of this study was to determine the spatial
dispersion of soil microbial and free-living nematode communities in the open sites (between shrubs) in the upper (0–10 cm)
soil layer at four altitudes on both slopes. The combination of relative soil moisture availability and temperature, known
to be one of the main triggers for soil biota activity, was explained by slope orientation. The above-mentioned differences
were found to significantly affect microbial biomass and CO2 evolution resulting in temporary stress, corresponding to higher values in metabolic quotient (qCO2) values. These differences may represent microbial investment in energy in order to overcome stress resulting from the microclimatic
differences between the two slopes. Moreover, the degree of substrate limitation (primary production due to the differences
in plant cover) of microbial activity was explained by the difference in microbial functional groups. The total abundance
of soil free-living nematodes was found to be 2-fold higher on the SFS than on the NFS. Thirty-nine genera, including 12 bacteria-feeders,
5 fungi-feeders, 12 plant-parasites, and 10 omnivore-predators, were found at the study site, with 34 genera on the NFS and
29 on the SFS. The generic diversity of the bacteriafeeding nematodes was higher on the SFS than on the NFS. This study elucidates
the importance of slope orientation and its effect on the structural levels of soil microbial and nematode communities. 相似文献
10.
To date, the small nuclear 4.5SI RNA has only been studied in the rat (Rattus norvegicus). Combining PCR and hybridization analyses, we have revealed 4.5SI RNA homologues sequences in the genomes of four myomorph rodent families (Muridae, Cricetidae, Spalicidae, and Rhizomyidae),
and not in other myomorph families (Dipodidae, Zapodidae, Geomyidae, and Heteromyidae) or sciuromorph and caviomorph rodents.
By Northern-hybridization, 4.5SI RNA has been detected in the common rat (R. norvegicus, Muridae), golden hamster (Mesocricetus auratus, Cricetidae), and Russian mole rat (Spalax microphthalmus, Spalacidae), but not in the related great jerboa (Allactaga jaculus, Dipodidae) or in four non-myomorph rodent species tested. cDNA derived from 4.5SI RNA of M. auratus and S. microphthalmus has been cloned and sequenced. The hamster RNA is found to differ from rat 4.5SI RNA by only one nucleotide substitution. For the mole rat, two variants of 4.5SI RNA are detected: short (S) and long (L) with length 101 and 108 nt, respectively. The L variant differs from the S variant
as well as from murid and cricetid 4.5SI RNAs by both a 7 nt insertion and a varying number of nucleotide substitutions. The sequence similarity between the spalacid
S-variant and murid/crecitid variants of 4.5SI RNA is 90%. Judging from species distribution, 4.5SI RNA genes emerged during the same period of time as the related short interspersed element B2 arose. This occurred after
the divergence of Dipodidae lineage but before the branching of Spalicidae/Rhizomyidae lineage from a common myomorph rodent
stem. S variant genes seemed to emerge in a common ancestor of spalacids and rhizomyds whereas L variant genes formed in spalacids
following the divergence of these two families. The low rate of evolutionary changes of 4.5SI RNA, at least, in murids and cricetids (6 × 10−4 substitutions per site per million years), suggests that this RNA is under selection constraint and have a function. This
is a remarkable fact if the recent origin and narrow species distribution range of 4.5SI RNA genes is taken into account. Genes with narrow species distribution are proposed to be referred to as stenogenes.
Received: 11 December 2000 / Accepted: 27 August 2001 相似文献
11.
An oligodeoxynucleotide probe (GSB-532) specific for green sulfur bacteria was developed. Highly stringent hybridization
conditions were established using whole cells of Chlorobium limicola DSM249 immobilized on glass slides. At a formamide concentration of 10%, the optimum specificity was reached at 47 °C. When
a conventional fixation procedure was used, a conspicuous autofluorescence developed within the cells. This autofluorescence
was due to the liberation of bacteriochlorophyll by the detergent Triton X-100 and a subsequent conversion to bacteriopheophytin
and related compounds. The signal-to-noise ratio could be increased by a final dehydration of the samples with methanol. Finally,
the method was adapted to the hybridization of natural samples collected on polycarbonate membrane filters. In situ hybridization
of pure cultures, various enrichments, and natural samples from the chemocline of a freshwater lake confirmed that probe GSB-532
hybridized exclusively to cells of green sulfur bacteria. Our protocol allows the highly specific detection of green sulfur
bacteria in water samples and a rapid screening of natural bacterial communities. Employing probe GSB-532, the phylogenetic
affiliation of the epibionts in “Chlorochromatium aggregatum” and “Pelochromatium roseum” could be demonstrated for the first time.
Received: 26 October 1998 / Accepted: 7 January 1999 相似文献
12.
V. B. Sapunov 《Human Evolution》1995,10(3):193-198
Ecological twin species are closely related species inhabiting the same ecological niche. Both micro- and macroevolutions
proceed faster in a twin system than within a single species. One proposed hypothesis is that the acceleration of hominoid
evolution was caused by the existence of ecological twin species. The complementary species for Homo habilis and Homo erectus
were Australopithecus species. Both paleontological and cryptozoological data suggest that Homo sapiens has a complementary
species as well. A small population of the latter may still exist today. Specific interaction within the system of two species
explains the difficulty in detecting ecological twins of the species. The existence of a hypothetical human species provides
the basis of popular talk of a “wildman”. 相似文献
13.
A detailed analysis of the evolutionary history of hepatitis B virus (HBV) was undertaken using 39 mammalian hepadnaviruses
for which complete genome sequences were available, including representatives of all six human genotypes, as well as a large
sample of small S gene sequences. Phylogenetic trees of these data were ambiguous, supporting no single place of origin for
HBV, and depended heavily on the underlying model of DNA substitution. In some instances genotype F, predominant in the Americas,
was the first to diverge, suggesting that the virus arose in the New World. In other trees, however, sequences from genotype
B, prevalent in East Asia, were the most divergent. An attempt was also made to determine the rate of nucleotide substitution
in the C open reading frame and then to date the origin of HBV. However, no relationship between time and number of substitutions
was found in two independent data sets, indicating that a reliable molecular clock does not exist for these data. Both the
pattern and the rate of nucleotide substitution are therefore complex phenomena in HBV and hinder any attempt to reconstruct
the past spread of this virus.
Received: 5 December 1998 / Accepted: 23 February 1999 相似文献
14.
Nickel-, cadmium-, and chromium-resistant mutants of Psedomonas aeruginosa sp. NBRI 4014 are potent growth promontory strains. In the presence of metal(s), they have shown increased cell morphology
and could accumulate nickel (2.0874 mM/g), cadmium (2.295 mM/g), and chromium (2.997 mM/g) at pH 9. However, chromium accumulation was maximum, but the toxicity levels of nickel, cadmium, and chromium was ranged
from 90 to 504 μM of used metal(s). Bioaccumulation increases up to the fifth day at the highest used metal concentration and then became constant.
This suggests their exploitation for detoxification and subsequently loaded biomass treatment for the recovery of accumulated
metal(s). 相似文献
15.
16.
Short interspersed DNA elements (SINEs) amplify by retroposition either by (i) successive waves of amplification from one
or a few evolving master genes or by (ii) the generation of new master genes that coexist with their progenitors. Individual,
highly conserved, elements of the B1 SINE family were identified from the GenBank nucleotide database using various B1 subfamily
consensus query sequences to determine their integration times into the mouse genome. A comparison of orthologous loci in
various species of the genus Mus demonstrated that four subfamilies of B1 elements have been amplifying within the last 1–3 million years. Therefore, B1 sequences
are generated by coexisting source genes. Additionally, three B1 subfamilies have been concurrently propagated during subspecies
divergence and strain formation in Mus, indicating very recent activity of this retroposon family. The patterns of intra- and interspecies variations of orthologous
loci demonstrate the usefulness of B1 integrations as a phylogenetic tool. A single inconsistency in the phylogenetic trends
was depicted by the presence of a B1 insert in an orthologous locus exclusively in M. musculus and M. pahari. However, DNA sequence analysis revealed that these were independent integrations at the same genomic site. One highly conserved
B1 element that integrated at least 4–6 million years ago suggests the possibility of occasional function for B1 integrations.
Received: 25 February 2000 / Accepted: 5 June 2000 相似文献
17.
J. Kieler P. Briand M. C. Van Peteghem M. Mareel 《In vitro cellular & developmental biology. Plant》1979,15(10):758-771
Summary Two types of apparently spontaneous malignant alterations of fibroblastlike ST/a mouse lung cells (ST-L cells) grown in vitro
are described. One type is characterized by a high tumorigenic potential of the altered cells in nonconditioned syngeneic
recipients, a fibro-blastlike morphology with cell surface showing very few microvilli by scanning electron-microscopy (SEM),
and a growth pattern typical of nontransformed cells. These cells were described as R− cells. The other type is characterized by a low tumorigenic potential in nonconditioned, immunocompetent syngeneic recipients,
rounding up of the cells which by SEM showed numerous microvilli on the surface, and a growth pattern typical of transformed
cells. These cells were described as round cells or R+ cells. In immunoincompetent mice, R+ cells readily produced sarcomas, which grew faster than those produced by R− cells. Both types of ST-L cells expressed murine leukemia virus (MuLV) when tested in a peroxidase anti-p30 plaque test.
The concentration of murine leukemia virus envelope glycoprotein (gp70) has previously (5) been shown to be threefold higher
in R+ cells compared to R− cells. Furthermore, round-cell transformation was accompanied by the development of crossreacting rejection antigens protective
against a secondary challenge with Ehrlich ascites tumor and with syngeneic dimethylbenzanthracene induced ST/a mouse leukemia
(STABAL). A similar protection was obtained by preimmunization with a cloned embryonic feral mouse cell line (SC-1) infected
with ST-L virus as well as with virus-free SC-1 cells, suggesting the presence of rejection antigens both of viral (gp70)
and nonviral origin.
Sponsored by the Danish Cancer Society.
Supported by the Kankerfonds van de Algemene Spaar-en Lijfrentekas.
The SC-1 cell line was originally provided by contract E-73-2001-N01 within the Special Virus-Cancer Program NIH, USPHS, through
the courtesy of Walter A. Nelson-Rees, Naval Biomedical Research Laboratory, Oakland, California, and Wallace P. Rowe, Laboratory
of Viral Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland.
The financial support of the Daell Foundation, the Schepler Foundation, the Jorgen Holm Foundation and the Danish National
Research Foundation is gratefully acknowledged. 相似文献
18.
Hughes AL 《Journal of molecular evolution》1999,48(5):565-576
It has been proposed that two rounds of duplication of the entire genome (polyploidization) occurred early in vertebrate
history (the 2R hypothesis); and the observation that certain gene families important in regulating development have four
members in vertebrates, as opposed to one in Drosophila, has been adduced as evidence in support of this hypothesis. However, such a pattern of relationship can be taken as support
of the 2R hypothesis only if (1) the four vertebrate genes can be shown to have diverged after the origin of vertebrates,
and (2) the phylogeny of the four vertebrate genes (A–D) exhibits a topology of the form (AB) (CD), rather than (A) (BCD).
In order to test the 2R hypothesis, I constructed phylogenies for nine protein families important in development. Only one
showed a topology of the form (AB) (CD), and that received weak statistical support. In contrast, four phylogenies showed
topologies of the form (A) (BCD) with statistically significant support. Furthermore, in two cases there was significant support
for duplication of the vertebrate genes prior to the divergence of deuterostomes and protostomes: in one case there was significant
support for duplication of the vertebrate genes at least prior to the divergence of vertebrates and urochordates, and in one
case there was weak support for duplication of the vertebrate genes prior to the divergence of deuterostomes and protostomes.
Taken together with other recently published phylogenies of developmentally important genes, these results provide strong
evidence against the 2R hypothesis.
Received: 22 December 1997 / Accepted: 5 October 1998 相似文献
19.
We carried out an analysis of partial sequences from expressed major histocompatibility complex (MHC) class I genes isolated
from a range of equid species and more distantly related members of the mammalian order Perissodactyla. Phylogenetic analysis
revealed a minimum of six groups, five of which contained genes and alleles that are found in equid species and one group
specific to the rhinoceros. Four of the groups contained only one, or very few sequences, indicating the presence of relatively
nonpolymorphic loci, while another group contained the majority of the equid sequences identified. These data suggest that
a diversification of MHC genes took place after the split between the Equidae and the Rhinocerotidae yet before the speciation
events within the genus Equus.
Received: 17 November 1998 / Accepted: 7 April 1999 相似文献
20.
Molecular Evidence on the Evolutionary and Biogeographical Patterns of European Cyprinids 总被引:21,自引:0,他引:21
The phylogenetic relationships of 106 European cyprinid taxa were determined based on the complete nucleotide sequence (1140
bp) of the mitochondrial cytochrome b gene. The molecular phylogeny was used (1) to revise the current systematics of European cyprinids, (2) to establish the
phylogenetic utility of traditional morphological characters that are widely used in Cyprinidae systematics, and (3) to discuss
alternative hypotheses on the biogeography of the family in Europe. The age of the major lineages within European cyprinids
was tentatively estimated with a molecular clock and showed full agreement with the fossil record of the group. Moreover,
the results provided unambiguous evidence for a close phylogenetic affinity of some Caucasian and Greek endemic cyprinid taxa
(e.g., B. capito and B. brachycephalus and Leuciscus keadicus, Barbus graecus, and B. albanicus, respectively) to Iberian and North African, but not Central European, cyprinids. The existence of such unexpected phylogenetic
relationships refutes the classical hypothesis on the biogeography of European cyprinids, which assumes a dispersal of the
cyprinid fauna from central Europe to southern Europe and northern Africa during the Miocene (and, hence, predicts a close
phylogenetic relationship of all Caucasian, Greek, Iberian, and North African cyprinids to central European taxa). Instead,
the existence of a Mediterranean realm independent of the central European route seems plausible based on the molecular evidence.
It is likely that the new biogeographical scenario proposed here might apply to other primary freshwater European animals
with low dispersal abilities, including fish, amphibians, and invertebrates.
Received: 2 February 1999 / Accepted: 16 March 1999 相似文献