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1.
The tetra-aza ligand 3,6-bis(2′-pyridyl)pyridazine (L), when reacting in appropriate conditions with Cu(II) halides, gives rise to polynuclear complexes of general formula [Cu2L(OH)X3]n (X = Cl or Br). The bromine derivative has been studied by X-ray analysis. The crystals are twins by merohedry of class I, space group Pn (P21/n apparent space group), with the following cell constants: a = 13.691(5), b = 6.245(3), c = 10.298(4) Å, β = 103.92(5)°. The structure was refined by least-squares techniques to a final R factor of 0.066. The structure consists of binuclear units joined to each other through bridging bromine atoms to form a polymeric array. The two independent copper atoms of the dinuclear moiety are five-coordinated with a geometry which is intermediate between a square-pyramid and a trigonal-bipyramid.  相似文献   

2.
The mtDNA variation has been studied in representatives of the Russkoe Ust’e (n = 30), Kolyma (n = 31), and Markovo (n = 26) ethnic subgroups originating from Russian military men, hunters, and fishers who married local Yukaghir women and settled at the Arctic Ocean coast and on the Anadyr’ River more than 350 years ago. The mtDNA haplotypes characteristic of indigenous Siberian peoples have been demonstrated to form the basis of the mitochondrial gene pool of Russian old settlers of the region. Only one of 30 identified haplotypes belonging to 11 haplogroups (H2a) is characteristic of European populations. The C and D haplogroups are the most diverse. The analysis has revealed the characteristics of the population structure of the Russian old settlers and allowed them to be interpreted in terms of recent historical and environmental processes.  相似文献   

3.
New data are presented on chromosome numbers for 36 species, two varieties, and two hybrids ofCirsium (Compositae). These include first reports forC. rhothophilum (2n = 34),C. andrewsii (2n = 32),C. crassicaule (2n = 32),C. quercetorum (2n= 32, 112),C. pascuarense (2n= 32),C. douglasii var.canescens (2n = 30, 34),C. hydrophilum (2n = 32),C. neomexicanum (2n = 30),C. cymosum (2n = 30, 34),C. acantholepis (2n= 34),C. radians (2n = 34), C.grahami (2n = 32),C. nigriceps (2n = 36),C. andersonii (2n= 32, 64),C. anartiolepis (2n = 34), andC. subcoriaceum (2n= 34). The published data on chromosome numbers of Eurasian and AmericanCirsium are summarized. In Eurasia, speciation has taken place primarily at the diploid level but is occasionally reinforced by polyploidy. The ancestral base number of 17 has been preserved in almost all species, and there is little evidence that reduction in chromosome number has played a significant role in speciation. In America speciation has proceeded exclusively at the diploid level, but the ancestral genome of 17 chromosomes has been retained in only about half of the species examined. In the remaining species, restructuring of the genome has occurred resulting in a reduction in number from 17 to 9 in extreme cases. Polyploidy, when seen, is of no significance. It is suggested that all species with greatly reduced numbers may represent products of a single reduction series.  相似文献   

4.
The present paper deals with cytological studies on 31 populations covering 17 species belonging to 10 genera of Apiaceae from Western Himalayas. The chromosome numbers in the two species as Chaerophyllum capnoides (n = 11) and Heracleum brunonis (n = 11), along with additional cytotypes for Pimpinella acuminata (n = 9) and Sium latijugum (n = 12) have been reported for the first time on world-wide basis. The genus Pleurospermum, although cytologically worked out earlier from outside India, its species densiflorum (n = 11) makes first representation of the genus from India. Besides, the chromosome number in Chaerophyllum aromaticum (n = 11) have been worked out for the first time from India. The course of meiosis varies from normal to abnormal in different populations of Chaerophyllum villosum, Pimpinella achilleifolia and Sium latijugum while abnormal meiotic course has been observed in all the studied populations of Chaerophyllum acuminatum, C. aromaticum, C. capnoides, Pimpinella acuminata, P. diversifolia, Pleurospermum densiflorum and Vicatia coniifolia. Such taxa are marked with meiotic abnormalities in the form of cytomixis, chromatin stickiness, formation of laggards and bridges resulting into abnormal microsporogenesis. The occurrence of structural heterozygosity has been recorded in the Chaerophyllum acuminatum and C. aromaticum. The effect of these abnormalities is clearly seen on the pollen size and fertility.  相似文献   

5.
The suggestion that the fish specimens caught in the littoral zone off Nedorazumeniya Island, Taui Bay, Sea of Okhotsk, belong to the eelpout species Magadanichthys skopetsi [23] and Hadropareia middendorffii Schmidt, 1904 has been confirmed by the analysis of their molecular-genetic and morphological characters. Their karyotypes have been studied for the first time: M. skopetsi, 2n = 48 (2 meta-, 26 subtelo-, and 20 acrocentric chromosomes), NF = 50; H. middendorffii, 2n = 48 (2 meta-, 36 subtelo-, and 10 acrocentric chromosomes), NF = 50. As a result of a comprehensive study, the levels of interspecific differentiation of these species has been established, the degree of intraspecific variability has been determined, and the lack of the population-geographical subdivision of H. middendorffii has been shown.  相似文献   

6.
The dominant mammals occupying the subterranean niche in South America are rodents of the genus Ctenomys, which form a large group of 56 species with chromosome numbers ranging from 2n= 10 to 70. In southern Brazil, Ctenomys minutus is the species with the widest geographic distribution, inhabiting sandy fields and dunes extending from Jaguaruna beach in the state of Santa Catarina to the town of São José do Norte in the state of Rio Grande do Sul. Eleven karyotypes (2n= 42; 2n= 46a; 2n= 46b; 2n= 47a; 2n= 47b; 2n= 48a; 2n= 48b; 2n= 49a; 2n= 49b; 2n= 50a and 2n= 50b) were described for this species and zones of hybridization are also known. A sample of 51 C. minutus specimens was collected from five sampling sites about 20 km apart along the coastal plain of Rio Grande do Sul between the municipalities of Tavares (31°23′S 51°09′W) and São José do Norte (31°52′S 51°54′W). We were able to extend the known geographic distribution of C. minutus by 90 km, from Tavares southwards to São José do Norte. During our study we found five karyotypes (2n= 46b, 47b, 48b, 49b and 50b), four of which (2n= 47b, 48b, 49b and 50b) have not previously been described for this species.  相似文献   

7.
The present study revealed the varied frequency of natural chromosomal abnormalities in 13 populations pertaining to 9 species of the genus Artemisia L. from different localities of Himachal Pradesh (Western Himalaya). Intraspecific chromosome variability has been reported for the first time on worldwide basis in Artemisia vestita (2n = 2x = 36) and from India in A. macrocephala (2n = 2x = 18) and A. scoparia (2n = 2x = 36). Besides, B-chromosomes have been reported here for the first time in A. nilagirica and A. roxburghiana. Most of the populations show anomalous meiotic behaviour resulting in cytomixis, chromosomal stickiness, unoriented bivalents, formation of laggards and bridges which leads to abnormal microsporogenesis, and production of heterogeneous-sized fertile pollen grains along with reduced pollen fertility.  相似文献   

8.
Karyological study of larch population members from different parts of the Larix olgensis L. Henry areal in the Primorskii krai has been carried out. The main amount of chromosomes for larch as n = 12 (2n = 24) has been confirmed. Mixoploidy was observed in all studied populations. The difference of individuals from the larch areal based on the cell amount with a different level of ploidity has been found in the population of L. olgensis locus classicus and both L. sibirica and L. gmelinii, which is probably a consequence of their hybrid nature.  相似文献   

9.
Evolution and taxonomic split of the model grass Brachypodium distachyon   总被引:1,自引:0,他引:1  

Background and Aims

Brachypodium distachyon is being widely investigated across the world as a model plant for temperate cereals. This annual plant has three cytotypes (2n =  10, 20, 30) that are still regarded as part of a single species. Here, a multidisciplinary study has been conducted on a representative sampling of the three cytotypes to investigate their evolutionary relationships and origins, and to elucidate if they represent separate species.

Methods

Statistical analyses of 15 selected phenotypic traits were conducted in individuals from 36 lines or populations. Cytogenetic analyses were performed through flow cytometry, fluorescence in situ hybridization (FISH) with genomic (GISH) and multiple DNA sequences as probes, and comparative chromosome painting (CCP). Phylogenetic analyses were based on two plastid (ndhF, trnLF) and five nuclear (ITS, ETS, CAL, DGAT, GI) genes from different Brachypodium lineages, whose divergence times and evolutionary rates were estimated.

Key Results

The phenotypic analyses detected significant differences between the three cytotypes and demonstrated stability of characters in natural populations. Genome size estimations, GISH, FISH and CCP confirmed that the 2n = 10 and 2n = 20 cytotypes represent two different diploid taxa, whereas the 2n = 30 cytotype represents the allotetraploid derived from them. Phylogenetic analysis demonstrated that the 2n = 20 and 2n = 10 cytotypes emerged from two independent lineages that were, respectively, the maternal and paternal genome donors of the 2n = 30 cytotype. The 2n = 20 lineage was older and mutated significantly faster than the 2n = 10 lineage and all the core perennial Brachypodium species.

Conclusions

The substantial phenotypic, cytogenetic and molecular differences detected among the three B. distachyon sensu lato cytotypes are indicative of major speciation processes within this complex that allow their taxonomic separation into three distinct species. We have kept the name B. distachyon for the 2n = 10 cytotype and have described two novel species as B. stacei and B. hybridum for, respectively, the 2n = 20 and 2n = 30 cytotypes.  相似文献   

10.
Fluorescence resonance energy transfer (FRET), measured by fluorescence intensity-based microscopy and fluorescence lifetime imaging, has been used to estimate the size of oligomers formed by the M2 muscarinic cholinergic receptor. The approach is based on the relationship between the apparent FRET efficiency within an oligomer of specified size (n) and the pairwise FRET efficiency between a single donor and a single acceptor (E). The M2 receptor was fused at the N terminus to enhanced green or yellow fluorescent protein and expressed in Chinese hamster ovary cells. Emission spectra were analyzed by spectral deconvolution, and apparent efficiencies were estimated by donor-dequenching and acceptor-sensitized emission at different ratios of enhanced yellow fluorescent protein-M2 receptor to enhanced green fluorescent protein-M2 receptor. The data were interpreted in terms of a model that considers all combinations of donor and acceptor within a specified oligomer to obtain fitted values of E as follows: n = 2, 0.495 ± 0.019; n = 4, 0.202 ± 0.010; n = 6, 0.128 ± 0.006; n = 8, 0.093 ± 0.005. The pairwise FRET efficiency determined independently by fluorescence lifetime imaging was 0.20–0.24, identifying the M2 receptor as a tetramer. The strategy described here yields an explicit estimate of oligomeric size on the basis of fluorescence properties alone. Its broader application could resolve the general question of whether G protein-coupled receptors exist as dimers or larger oligomers. The size of an oligomer has functional implications, and such information can be expected to contribute to an understanding of the signaling process.  相似文献   

11.
Cytological studies have been carried out on 12 species of Brassicaceae Burn. on population basis from different geographical areas of Kashmir and Himachal Pradesh in the Western Himalayas. Variable chromosome reports for Barbaraea intermedia (n = 16), Cardamine loxostemonoides (n = 8), Nasturtium officinale (n = 8), Sisymbrium orientale (n = 14) on world-wide basis have been added to the previous reports of these species. The chromosome numbers in seven species as Barbaraea intermedia (n = 8), B. vulgaris (n = 8), Capsella bursa-pastoris (n = 8), Descuriania Sophia (n = 10), Rorippa islandica (n = 8), Sisymbrium strictum (n = 7) and Thlaspi alpestre (n = 7) have been worked out for the first time from India. The meiotic course in the populations of seven species such as Barbaraea intermedia, Capsella bursa-pastoris, Coronopus didymus, Descuriania sophia, Nasturtium officinale, Sisymbrium orientale and S. strictum varies from normal to abnormal while all the populations of two species Barbaraea vulgaris and Sisymbrium irio show abnormal meiotic course. Meiotic abnormalities are in the form of cytomixis, chromosomal stickiness, unoriented bivalents, inter-bivalent connections, formation of laggards and bridges, all resulting into abnormal microsporogenesis. Heterogenous sized fertile pollen grains and reduced reproductive potentialities have invariably been observed in all the meiotically abnormal populations. However, the meiotic course in all the populations of Cardamine loxostemonoides, Rorippa islandica and Thalspi alpestre is found to be normal with high pollen fertility.  相似文献   

12.
Sodium extrusion by internally dialyzed squid axons   总被引:25,自引:19,他引:6  
A method has been developed which allows a length of electrically excitable squid axon to be internally dialyzed against a continuously flowing solution of defined composition. Tests showed that diffusional exchange of small molecules in the axoplasm surrounding the dialysis tube occurred with a half-time of 2–5 min, and that protein does not cross the wall of the dialysis tube. The composition of the dialysis medium was (mM): K isethionate 151, K aspartate 151, taurine 275, MgCI2 4–10, NaCl 80, KCN 2, EDTA 0.1, ATP 5–10, and phosphoarginine 0–10. The following measurements were made: resting Na influx 57 pmole/cm2sec (n = 8); resting potassium efflux 59 pmole/ cm2sec (n = 4); stimulated Na efflux 3.1 pmole/cm2imp (n = 9); stimulated K efflux 2.9 pmole/cm2imp (n = 3); resting Na efflux 48 pmole/cm2sec (n = 18); Q 10 Na efflux 2.2 (n = 5). Removal of ATP and phosphoarginine from the dialysis medium (n = 4) or external application of strophanthidin (n = 1) reversibly reduced Na efflux to 10–13 pmole/cm2sec. A general conclusion from the study is that dialyzed squid axons have relatively normal passive permeability properties and that a substantial fraction of the Na efflux is under metabolic control although the Na extrusion mechanism may not be working perfectly.  相似文献   

13.
Karyotypic studies were carried out on some species belonging to the family Cebidae. The chromosome complements have been studied in blood cultures in vitro in the following species: Alouatta fusca clamitans (2n = 50); Aotes trivirgatus (2n = 52); Cebus albifrons (2n = 52); Cebus sp. (2n = 54); Ateles paniscus paniscus (2n = 34); Lagothrix lagotricha (2n = 62). Comparison between the present results and the karyotypes of the Cebidae described in the literature reveal intraspecific and interspecific variability in number and structure of the chromosomes.  相似文献   

14.
15.
The center of diversity of Argentinean orchids is in the northeast region of the country. Chromosome numbers and karyotype features of 43 species belonging to 28 genera are presented here. Five chromosome records are the first ones at the genus level; these taxa are Aspidogyne kuckzinskii (2n = 42), Eurystyles actinosophila (2n = 56), Skeptrostachys paraguayensis (2n = 46), Stigmatosema polyaden (2n = 40) and Zygostates alleniana (2n = 54). In addition, a chromosome number is presented for the first time for 15 species: Corymborkis flava (2n = 56), Cyclopogon callophyllus (2n = 28), C. oliganthus (2n = 64), Cyrtopodium hatschbachii (2n = 46), C. palmifrons (2n = 46), Galeandra beyrichii (2n = 54), Habenaria bractescens (2n = 44), Oncidium edwallii (2n = 42), O. fimbriatum (2n = 56), O. pubes (2n = 84), O. riograndense (2n = 56), Pelexia ekmanii (2n = 46), P. lindmanii (2n = 46) and Warrea warreana (2n = 48). For Oncidium longicornu (2n = 42), O. divaricatum (2n = 56) and Sarcoglottis fasciculata (2n = 46+1B?, 46+3B?), a new cytotype was found. Chromosome data support phylogenetic relationships proposed by previous cytological, morphologic and molecular analyses, and in all the cases cover some gaps in the South American literature on orchid chromosomes.  相似文献   

16.
A 171ACS line (AABBDD, 2n = 6x = 42) has been crossed with the tetra-(AABB and AAGG, 2n = 4x = 28) and octoploid (AAAABBGG, 2n = 8x = 56) wheat species without the D genome, as well as with hexaploid (AABBDD and AAGGDD, 2n = 6x = 42) wheat species and tetra-(AADD, 2n = 4x = 28) and hexaploid (AADDSS, 2n = 6x = 42) amphidiploids that have the D genome. The inheritance of a novel type of spike branching in these obtained hybrid populations F1–F3 was studied. According to the results of a morphogenetic analysis of hybrid populations derived from crossings between 171ACS and wheat species without the D genome, the novel type of branching was found to be controlled by a single recessive gene (although a phenotype of the 171ACS line gives a handle for a doubt about occurrence of the second gene) and the 171ACS line is a source of the novel type branching. However, not a single branched spike plant was observed in hybrid populations that were produced by crosses of the 171ACS line with wheat species, as well as with amphidiploids that have the D genome. This result also experimentally confirmed the inhibitor effect of chromosomes of the D genome on the expression of the spike-branching trait. The appearance of branched-spike forms, together with normal spiked plants in hybrid populations of the 171ACS line and T. araraticum Jakubz. (AAGG) or T. fungicidum Zhuk. (AAAABBGG) confirmed that, as opposed to the D genome, neither genome G nor genome B demonstrated the inhibition of the expression of the spikebranching trait. In conclusion, keeping in mind that branching is exhibited in hybrid progenies obtained from crosses between the 171ACS line and wheat species with AABB and AAGG genomes, it can be said that this gene belongs to the A genome.  相似文献   

17.
1) The self-association of both caffeine (Cf) and 5'-adenosine monophosphate (AMP) in aqueous solution has been reinvestigated by 1H NMR. The self-association process is characterized by an isodesmic model. The apparent self-association constants of the vertical stacking process are KCf= (10.6 ± 1.0) M?1 and kamp = (1.67 ± 0.17) M?1. The arrangement of the monomeric units in the stacked aggregates is discussed in terms of isoshielding curves theoretically calculated by Giessner-Prettre and Pullman. Models are proposed which are consistent with these and further previous NMR data. 2) The interaction of Cf and AMP has been studied by ?1 H NMR. The apparent association constant of the complex Cf-AMP is KC-A = (7.3 ± 1.2) M?1.Two models of the mutual arrangement of AMP and Cf in the complex are proposed on the basis of the calculated isoshielding curves considering both ring current and local atomic diamagnetic anisotropy effects. 3) The interaction of Cf and poly(riboadenylate), (rA)n is indicated by a downfield shift of the H-8 line but an upfield shift of the H-2 line in the 1H NMR spectra of (rA)n. The concentration dependence of the 1H NMR shifts of both Cf and (rA)n can be explained by the existence of two binding mechanisms. We suggest (i) partial insertion of Cf between adjacent base residues of ordered single-stranded regions of (rA)n and (ii) outside binding of Cf in form of monomeric Cf as well as of self-associated aggregates. The complex geometry of insertion proposed on the basis of the calculated isoshielding curves is characterized by a stronger overlapping of the Cf ring and the H-2 proton of (rA)n as compared to the H-8 proton.  相似文献   

18.
Repeated interaction promotes cooperation among rational individuals under the shadow of future, but it is hard to maintain cooperation when a large number of error-prone individuals are involved. One way to construct a cooperative Nash equilibrium is to find a ‘friendly-rivalry’ strategy, which aims at full cooperation but never allows the co-players to be better off. Recently it has been shown that for the iterated Prisoner’s Dilemma in the presence of error, a friendly rival can be designed with the following five rules: Cooperate if everyone did, accept punishment for your own mistake, punish defection, recover cooperation if you find a chance, and defect in all the other circumstances. In this work, we construct such a friendly-rivalry strategy for the iterated n-person public-goods game by generalizing those five rules. The resulting strategy makes a decision with referring to the previous m = 2n − 1 rounds. A friendly-rivalry strategy for n = 2 inherently has evolutionary robustness in the sense that no mutant strategy has higher fixation probability in this population than that of a neutral mutant. Our evolutionary simulation indeed shows excellent performance of the proposed strategy in a broad range of environmental conditions when n = 2 and 3.  相似文献   

19.
The crystal structures of two polymorphic complexes of Cd(II) with 2'-deoxy cytidine 5'-mono-phosphate (5'-dCMP) are reported and discussed The orthorhombic complex, [Cd(5'-dCMP) (H2O)2] (1), crystallizes in space group P212121 with cell dimensions a = 8.422(2), b = 24.428(8), c = 7.292(2) Å, and Z = 4, the monoclinic complex, [Cd2(5'-dCMP)2(H2O)2]·3H2O (2), crystallizes in space group C2 with a = 30.809(9), b = 5.369(2), c = 25.126(8) Å, β = 127.61(2)°, and Z = 4 Structure (1) has been solved by Patterson and Fourier methods, and structure (2) has been deduced from its isomorphous ribo-analog (J.K. Shiba and R. Bau, Inorg.Chem. 17, 3484 (1978)); and both have been refined by full-matrix least-squares methods to final R values of 0.052 for (1) and 0.103 for (2) using, respectively, 1273 and 2287 independent reflections. The orthorhombic complex (1) is three-dimensionally polymeric, with the Cd atom bound in a distorted octahedral arrangement to the cytosine base at N(3) and O(2) [Cd-N(3) 2.29(1) and Cd-O(2) 2.64(1) Å], to two phosphate oxygens of different nucleotide molecules, and to two water molecules, each phosphate group links two Cd atoms, thereby producing an infinite [-Cd-O-P-O-Cd-]n spiraling column, which is additionally interconnected to neighboring columns via nucleotide bridges to give a layer-like polymeric structure. The monoclinic complex (2), which includes two crystallographically independent [Cd(5'-dCMP) (H2O)] units, is also three-dimensionally polymeric, with each Cd atom bound in a distorted pentagonal bipyramidal arrangement to N(3) and O(2) of the base [Cd-N(3) 2.35av and Cd-O(2) 2.73av Å], to four phosphate oxygens of three different nucleotide molecules, and to a water molecule, each phosphate group binds to three Cd atoms, thereby creating an infinite cross-linked spiral of sequences [-Cd-O-P-O-Cd-]n and [-Cd-O-Cd-]n that is further connected to adjacent spirals via nucleotide bridges to form large  相似文献   

20.
John R. Reeder 《Brittonia》1971,23(2):105-117
Chromosome numbers are reported for 105 collections which represent 59 species belonging to 35 genera. For two of these genera:Blepharoneuron andTriniochloa no documented chromosome counts have been published to date. Records for the following species:Aristida arizonica, A. pansa, A. schiedeana, Blepharoneuron tricholepis, Deschampsia pringlei, Eragrostis palmeri,Leptochloa viscida, Munroa squarrosa, Panicum vaseyanum, Setaria grisebachii, andTriniochloa stipoides are the first for these taxa. Counts of 2n = 28 forAgrostis perennans, 2n = 20 forAegopogon cenchroides, 2n = 20 forBuchloË dactyloides, 2n = 54 forDigitaria filiformis, 2n = 60 and 2n = ca. 74 forEragrostis intermedia, 2n = 32 forErioneuron grandiflorum andE. pilosum, 2n = 44 forHilaria cenchroides, 2n = 38 and 2n = ca. 180 forHilaria mutica, 2n = 40 forPereilema crinitum, 2n = 28 forScleropogon brevifolius, 2n = ca. 108 forSetaria leucopila, and 2n = 36 forOplismenus burmannii are different from any published report for these species. Cytological information on Mexican material of the following ten species:Agrostis perennans, Aristida hamulosa,Bouteloua aristidoides, Eragrostis cilianensis, Sporobolus nealleyi, Tridens muticus,Digitaria filiformis, Hackelochloa granularis, Oplismenus burmannii, andPennisetum ciliare is here presented for the first time.  相似文献   

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