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1.
We have studied by gravimetric measurements and FTIR spectroscopy the hydration of duplexes and triplexes formed by combinations of dA(n), dT(n), rA(n), and rU(n) strands. Results obtained on hydrated films show important differences in their hydration and in the structural transitions which can be induced by varying the water content of the samples. The number of water molecules per nucleotide (w/n) measured at high relative humidity (98% R.H.) is found to be 21 for dA(n).dT(n) and 15 for rA(n).rU(n). Addition of a third rU(n) strand does not change the number of water molecules per nucleotide: w/n=21 for rU(n)*dA(n).dT(n) and w/n=15 for rU(n)*rA(n).rU(n). On the contrary, the addition of a third dT(n) strand changes the water content but in a different way, depending whether the duplex is DNA or RNA. Thus, a loss of four water molecules per nucleotide is measured for dT(n)*dA(n).dT(n) while an increase of two water molecules per nucleotide is observed for dT(n)*rA(n).rU(n). The final hydration is the same for both triplexes (w/n=17). The desorption profiles obtained by gravimetry and FTIR spectroscopy are similar for the rA(n).rU(n) duplex and the rU(n)*rA(n).rU(n) triplex. On the contrary, the desorption profiles of the dA(n).dT(n) duplex and the triplexes formed with it (rU(n)*dA(n).dT(n) and dT(n)*dA(n).dT(n)) are different from each other. This is correlated with conformational transitions induced by varying the hydration content of the different structures, as shown by FTIR spectroscopy. Modifications of the phosphate group hydration and of the sugar conformation (S to N type repuckering) induced by decrease of the water content are observed in the case of triplexes formed on the dA(n).dT(n) duplex.  相似文献   

2.
Eleven new genera and 17 species are described, with one exception parasites on echinoderms: Trochostilifer gen. n. with T. domus sp.n. (type species) (Philippines) on Stylocidaris efftuens, T. mortenseni sp.n. (New Caledonia) on Prionocidaris australis and T. slriatus (Hedley) on P. baculosa annulifera; Ophioarachnicola biformis gen. et sp.n. (Solomon Is.) on Ophio-arachna incrassata; Hemiliostraca sloani sp.n. (Aldabra I.) on Ophiomyxa australis; Robil-lardia solida sp.n. (Loyalty Is.), host unknown. Ersilia Monterosato is transferred from Lacunidae to Eulimidae, E. stancyki sp.n. (Florida) is a parasite of Ophiolepis elegans. Hyper-mastus echinodisci sp.n. and H. sauliae sp.n. (both Borneo) are parasitic on Echinodiscus bisperforatus; Monogamus parasaleniae sp.n. (Tonga I.) on Parasalenia gratiosa. Scalari-balcis gen.n. is erected for Mucronalia angulata Mandahl-Barth. Concavibalcis scalaris gen. et sp.n. is described from the Philippines, host unknown. Echiuroidicola cicatricosa gen. et sp.n. (Malaysia) is a parasite on the echiuroid Ochetostoma erythrogrammon. Peasistilifer gen.n. (type species Mucronalia nitidula Pease) is erected for a group of holothurian parasites. Prostilifer gen.n. is erected for Eulima subpellucida Pease, parasitic on Pacific holo-thurians. Paramegadenus scutellicola sp.n. (Pacific) is parasitic on Stellaster incei, P. incerta sp.n. on an Australian starfish. Asterolamia hians gen. et sp.n. is described from Astropecten indicus and A. cingulata from Craspidaster hesperus , both Pacific. Microstilifer gen.n. is erected for Stilifer auricula Hedley. Vitreobalcis gen.n. is erected for Apicalia holdsworthi H. Adams, a parasite of Mespilia globulus and V. laevis sp.n. (from Synaptula purpurea , Australia) is provisionally placed here. Luetzenia asthenosomae gen. et sp.n. (Australia) and L. toki Habe are both parasites on Asthenosoma.  相似文献   

3.
国产姜科植物的染色体计数(5)   总被引:3,自引:0,他引:3  
<正> 本文继续对7属15种国产姜科植物作染色体计数观察,其中10种是染色体计数的新纪录(表、图)。通过对黄花大苞姜(Caulokaempferia coenobialis)和大苞姜(C.yunnanensis)以及凹唇姜(Bosenbevgia rotunda)和心叶凹唇姜(B.fallax)的染色体观察,确定了大苞姜属(Caulokaempferia)和凹唇姜属(Bosenbergia)的染色体基数分别为12和9。  相似文献   

4.
Sixteen nematode species of the order Chromadorida are described from the East Flower Garden at 72 m depth in the north-western Gulf of Mexico. The material is from sandy bottom samples influenced or beyond the influence of a sulphide-rich brine seep. Fifteen species are new to science: Acantholaimus quadridentatus sp.n., Prochromadorella papillata sp.n., Austranema mexicanum sp.n., Rhips anoxybiotica sp.n., Filitonchoides thiobioticus gen. et sp.n., Paracyatholaimus spinulaosus sp.n., Marylynnia punctata sp.n., Marylynnia johanseni sp.n., Acanthopharyngoides bidentatus sp.n., Desmodora (Croconema)punctata sp.n., Desmodora (Desmodora) curvispiculum sp.n., Desmodora (Pseudochromadora) bulbosa sp.n., Chromaspirinia longisetosa sp.n., Prochaetosoma brighti sp.n. and Ixonema powelli sp.n. A specimen of Bathyepsilonema is also described and is probably new to science, but the available material only includes a female.  相似文献   

5.
Photofootprinting of DNA triplexes.   总被引:11,自引:10,他引:1       下载免费PDF全文
We have used a photofootprinting assay to study intermolecular and intramolecular DNA triplexes. The assay is based on the fact that the DNA duplex is protected against photodamage (specifically, against the formation of the (6-4) pyrimidine photoproducts) within a triplex structure. We have shown that this is the case for PyPuPu (YRR) as well as PyPuPy (YRY) triplexes. Using the photofootprinting assay, we have studied the triplex formation under a variety of experimentally defined conditions. At acid pH, d(C)n.d(G)n.d(C)n and d(CT)n.d(GA)n.d(CT)n triplexes are detected by this method. The d(CT)n.d(GA)n.d(CT)n triplexes are additionally stabilized by divalent cations and spermidine. PyPuPu triplexes are pH-independent and are stabilized by divalent cations, such as Mg++ and Zn++. The effect depends on the type of cation and on the DNA sequence. The d(CT)n.d(GA)n.d(GA)n triplex is stabilized by Zn++, but not by Mg++, whereas the d(C)n.d(G)n.d(G)n triplex is stabilized by Mg++. In H-DNA, virtually the entire pyrimidine chain is protected against photodimerization, whereas only half of the pyrimidine chain participating in a triplex is protected in the CGG intramolecular triplex.  相似文献   

6.
Shear WA 《ZooKeys》2010,(52):9-46
The genus Trilasma Goodnight & Goodnight, 1942 is reinstated for Mexican ortholasmatines, and Cladolasma Suzuki, 1963 is reinstated for two species from Japan and Thailand, Cladolasma parvula Suzuki, comb. n. and Cladolasma angka (Schwendinger & Gruber), comb. n. Eight new species in the subfamily Ortholasmatinae Shear & Gruber, 1983 are described, as follows: Ortholasma colossussp. n. is from California, Trilasma tempestadosp. n., Trilasma hidalgosp. n., Trilasma trispinosumsp. n., Trilasma ranchonuevosp. n., Trilasma petersprouseisp. n. and Trilasma chipinquensis, sp. n. are from México, and Trilasma tropicumsp. n. from Honduras, the farthest south for a dyspnoan harvestman in the New World. A new distribution record for Martensolasma jocheni Shear 2006 is given. The recently described Upper Cretaceous amber fossil Halitherses grimaldii Giribet & Dunlop 2005 is not a member of the Ortholasmatinae, but is likely a troguloidean of an undiagnosed family.  相似文献   

7.
ABSTRACT .
The previously monotypic Papuan genus Heterochorista Diakonoff, 1952 is revised and twenty-one species are recognized. Nikolaia Diakonoff, 1953 is synonymized, syn.n. with Heterochorista. The following six species are placed in new combination in Heterochorista: Nikolaia melanopsygma Diakonoff, N.inumbrata Diakonoff, N.aperta Diakonoff, Isochorista papuana Diakonoff, I.polysperma Diakonoff and Dicellitis chrysonetha Diakonoff. Thirteen new species are added to Heterochorista: acomata sp.n., rostrata sp.n., trivialis sp.n., ornata sp.n., prisca sp.n., punctulata sp.n., rufulimaculata sp.n., classeyiana sp.n., spinosa sp.n., signata sp.n., fulgens sp.n., nitida sp.n. and aura sp.n. A checklist and a key to species are provided, and adults and male and female genitalia are described and illustrated. The phylogeny of Heterochorista is outlined on the basis of a cladistic character analysis and the genus is referred to the base of the Sparganothini. The apomorphies characterizing this tribe are reviewed with regard to their phylogenetic significance and the relationship between Sparganothini, Archipini and Atterini is briefly discussed.  相似文献   

8.
Li D  Huang H  Li X  Li X 《Bio Systems》2003,72(3):203-207
Recently, several DNA computing paradigms for NP-complete problems were presented, especially for the 3-SAT problem. Can the present paradigms solve more than just trivial instances of NP-complete problems? In this paper we show that with high probability potentially deleterious features such as severe hairpin loops would be likely to arise. If DNA strand x of length n and the 'complement' of the reverse of x have l match bases, then x forms a hairpin loop and is called a (n,l)-hairpin format. Let gamma=2l/n. Then gamma can be considered as a measurement of the stability of hairpin loops. Let p(n,l) be the probability that a n-mer DNA strand is a (n,l)-hairpin format, and q(n,l)((m)) be the probability that m ones are chosen at random from 4(n) n-mer oligonucleotides such that at least one of the m ones is a (n,l)-hairpin format. Then, q(n,l)((m))=1-(1-p(n,l))(m)=mp(n,l). If we require q(n,l)((m))相似文献   

9.
The potential Z-forming sequence (dT-dG)n . (dC-dA)n is an abundant, interspersed repeat element that is ubiquitous in eucaryotic nuclear genomes. We report that in contrast to eucaryotic nuclear DNA, the genomes of eubacteria, archaebacteria, and mitochondria lack this sequence, since even a single tract of greater than or equal to 14 base pairs in length is not detectable through either hybridization or sequence analysis. Interestingly, the phylogenetic distribution of the (dT-dG)n . (dC-dA)n repeat exhibits a striking parallel to that of (dT-dC)n . (dG-dA)n, but not to other homocopolymeric sequences such as (dC-dG)n . (dC-dG)n or (dT-dA)n . (dT-dA)n.  相似文献   

10.
Abstract. Analysis of thirty-four macrosteline and twenty-eight non-macrosteline leafhopper genera (Homoptera: Cicadellidae: Deltocephalinae) suggests that the ability to transmit plant viruses has arisen on at least three separate occasions within the Macrostelini. The tribe, including the Coryphaelini syn.n. and Balcluthini, is shown to be monophyletic. A revised diagnosis of the Macrostelini is presented, together with a key to genera. Five new genera and eight new species are described: Aderganna gen.n. , Cicadabara gen.n. Kadrabolina gen.n. , Masafuera gen.n. and Scaphosteles gen.n. , Yamatotettix remanei sp.n. , Masafuera oceanica sp.n. , Aderganna aethiopica sp.n. , A.nigra sp.n. , Scaphosteles nukahiva sp.n. , Kadrabolina elongata sp.n. , K.sinuata sp.n. and K.bispinosa sp.n. Four new combinations and five new synonymies are established: Cicadabara dorsalis (Osborn) comb.n. , C.minuta (Osborn) comb.n. , C.tintorella (Osborn) comb.n. , Balclutha thea (Distant) comb.n. , B.smaragdula Matsumura as a junior synonym of B.thea (Distant) syn.n. , B.modesta Ahmed, Murtaza & Malik as a junior synonym of B.incisa (Matsumura) syn.n. , B.karachiensis Ahmed, Murtaza & Malik as a junior synonym of B.rubrostriata (Melichar) syn.n. , B.versicoloroides Ghauri as a junior synonym of B.sternalis (Distant) syn.n. and B.knighti Rao & Ramakrishnan as a junior synonym of B.sujawalensis Ahmed syn.n.  相似文献   

11.
Ancilibracon gen.n. (type species: Ancilinracon townesi sp.n.). Ancilibracon bakeri sp.n., Gelasinibracon gen.n. (type species: Gelasinibracon sedlaceki sp.n.), Gelasinibracon simplicicaudatus sp.n., Esengoides gen.n. (type species: Esengoides crentdatus sp.n.) and Esengoides fulvus sp.n. are each described and illustrated. Ancilibracon towensi is from Malaysia. A. bakeri is from Borneo, both Gelasinibracon species are from Guinéa, E. crenulatus is from the solomon Islands and E. fulvus is from Australia. These three new genera belong to the Plesiobrscon Cameron group of the Braconina. Their relationship are discussed.  相似文献   

12.
It is well known that the periodic cycle {x(n)} of a periodically forced nonlinear difference equation is attenuant (resonant) if av(x(n)) < av(K(n))(av(x(n)) > av(K(n))),where {K ( n )} is the carrying capacity of the environment and av(t(n)) = (1/p)∑(p?1) (i=0) ti (arithmetic mean of the p-periodic cycle {t ( n )}). In this article, we extend the concept of attenuance and resonance of periodic cycles using the geometric mean for the average of a periodic cycle. We study the properties of the periodically forced nonautonomous delay Beverton-Holt model x(n+1) = r(n)x(n)/1 + (r(n?l) ? 1)x(n?k)/K(n?k), n= 0, 1, . . . , where {K ( n )} and {r ( n )} are positive p-periodic sequences; (K ( n )>0, r ( n )>1) as well as k and l are nonnegative integers. We will show that for all positive solutions {x ( n )} of the previous equation lim sup (n→∞) (∏(n?1)(i=0)xi)(1/n) ≤ ((∏(p?1)(i=0)ri)(1/p) ? 1)(∏(p?1)(i=0)(ri ? 1))(?1/p)(∏(p?1)(i=0)Ki)(1/p). In particular, in the case where {x(n)} is a p-periodic solution of the above equation (assuming that such solution exists) and r ( n )=r>1, the periodic cycle is g-attenuant, that is (∏(p?1)(i=0)x(i))(1/p)<(∏(p?1)(i=0)K(i))(p?1) Surprisingly, the obtained results show that the delays k and l do not play any role.  相似文献   

13.
A generic revision of the Phallodrilinae (Oligochaeta, Tubificidae)   总被引:3,自引:0,他引:3  
The generic classification of the subfamily Phallodrilinae (with a total of 252 species) is revised according to phylogenetic principles. Morphological character patterns are assessed under the principle of maximum parsimony, but due to the poor resolution and instability in the resulting cladograms, the analysis is supplemented with intuitive weighting of synapomorphic similarities. Thirty-one genera are recognized. The former definition of the type genus Phallodrilus Picrantoni, 1902, is revised and the members of this genus are reclassified into 20 taxa, each hypothesized to be monophyletic: Phallodrilus s.str . (revised to contain the type species only), Somalidrilus gcn.n., Milliganius gen.n., Phallodriloides gen.n., Albanidrilus gen.n., Abyssidrilus gen.n., Paraktedrilus gen.n., Uniporodrilus Erséus, 1979, Inermidrilus gen.n., Gianius gen.n., Mexidrilus gen.n., Peosidrilus Baker & Erséus, 1979, Atlantidrilus Erséus, 1983, Thalassodrilus Brinkhurst, 1963, Pirodrilus gen.n., Pirodriloides gen.n., Marionidrilus gen.n., Pectinodrilus gen.n., Pacifidrilus gen.n. and Pseudospiridion gen.n. Nine new species are described from the Northwest Atlantic: Phallodriloides pinnulatus sp.n., Abyssidrilus opulentus sp.n., A. potens sp.n., A. altoides sp.n., Mexidrilus obtusus sp.n., Peosidrilus dalei sp.n., P. aduncus sp.n., P. riseri sp.n., and Atlantidrilus hamulus sp.n. The genus Discordiprostatus Baker, 1982, is synonymized with Nootkadrilus Baker, 1982.  相似文献   

14.
Abstract. The genus Couturiera Disney, 1979, only known in the female sex, is synonymized with Perissa Borgmeier, 1967, only known in the male sex, a syn.n., thus solving the problem of the 'missing' males of the Alamirinae. Perissa kensmithi (Disney) comb.n., P.lewisi (Disney) comb.n. and P.orientalis (Disney & Peterson) comb.n. are transferred from Couturiera. Perissa couturieri Disney is synonymized under P. lewisi (Disney) and C.palawanensis Disney under P.georgei Disney. Perissa latiptera sp.n., P.oligoseta sp.n., P.tinglei sp.n. and Perittophora couturieri gen.n., sp.n., are described from Zimbabwe. A key to the twelve species of Alamirinae is provided. It is hypothesized that the Alamirinae may be paraphyletic, by virtue of exclusion of the Termitoxeniinae. The latter is probably polyphyletic, in that each Alamirinae genus is probably the sister group of a different Termi-toxeniin clade.  相似文献   

15.
In this paper we study the dynamical behavior of a class of neural networks where the local transition rules are max or min functions. We prove that sequential updates define dynamics which reach the equilibrium in O(n2) steps, where n is the size of the network. For synchronous updates the equilibrium is reached in O(n) steps. It is shown that the number of fixed points of the sequential update is at most n. Moreover, given a set of p < or = n vectors, we show how to build a network of size n such that all these vectors are fixed points.  相似文献   

16.
Crews SC  Harvey MS 《ZooKeys》2011,(99):1-104
We relimit and revise the family Selenopidae to include four new genera and 27 new species from Australia and the Oriental Region. The family is redefined, as are the genera Anyphops Benoit, Garcorops Corronca, Hovops Benoit, Selenops Latreille, and Siamspinops Dankittipakul & Corronca, to accommodate the new genera and to correct previous inconsistencies in the diagnoses and definitions of the aforementioned genera. The species of Selenops that occur throughout India and China are also reviewed. Three species occur in China: Selenops bursarius Karsch 1879, also known from Japan, Korea and Taiwan, Selenops ollarius Zhu, Sha, & Chen 1990, and Selenops radiatus Latreille 1819, the type of the genus and most widespread selenopid. Selenops cordatus Zhu, Sha & Chen syn. n. is recognized as a junior synonym of Selenops radiatus. Amamanganopsgen. n. is monotypic, with Amamanganops baginawasp. n. (♀; from the Philippines). Godumopsgen. n. is monotypic, with Godumops caritussp. n. (♂; from Papua New Guinea). Karaopsgen. n. occurs throughout Australia and includes 24 species. A new combination is proposed for Karaops australiensis (L. Koch 1875) comb. n. (ex. Selenops), and the new species: Karaops gangariesp. n. (♀, ♂), Karaops monteithisp. n. (♀), Karaops alanlongbottomisp. n. (♂), Karaops keithlongbottomisp. n. (♂), Karaops larryoosp. n. (♂), Karaops jarritsp. n. (♂,♀), Karaops marrayagongsp. n. (♀), Karaops ravenisp. n. (♂,♀), Karaops badgeraddasp. n. (♀), Karaops burbidgeisp. n. (♂,♀), Karaops karrawarlasp. n. (♂,♀), Karaops julianneaesp. n. (♀), Karaops martamartasp. n. (♀), Karaops manaaynsp. n. (♀, ♂), Karaops vadlaadambarasp. n. (♀, ♂), Karaops pilkingtonisp. n. (♀, ♂), Karaops deserticolasp. n. (♀), Karaops ngarutjaranyasp. n. (♂,♀), Karaops francesaesp. n. (♂,♀), Karaops toolbrunupsp. n. (♀, ♂), the type species Karaops ellenaesp. n. (♂,♀), Karaops jenniferaesp. n. (♀), and Karaops dawarasp. n. (♀).The genus Makdiopsgen. n. contains five species from India and Nepal. A new combination is proposed for Makdiops agumbensis (Tikader 1969), comb. n., Makdiops montigenus (Simon 1889), comb. n., Makdiops nilgirensis (Reimoser 1934) comb. n.,(ex. Selenops). Also, there are two new species the type of the genus Makdiops mahishasurasp. n. (♀; from India), and Makdiops shivasp. n. (♀). The genus Pakawopsgen. n. is monotypic. A new combination is proposed for Pakawops formosanus (Kayashima 1943) comb. n. (ex. Selenops), known only from Taiwan. A new combination is proposed for Siamspinops aculeatus (Simon)comb. n. (ex. Selenops). The distribution and diversity of the studied selenopid fauna is discussed. Finally, keys are provided to all of the selenopid genera and to the species of Karaopsgen. n.and Makdiopsgen. n.  相似文献   

17.
Hud NV  Feigon J 《Biochemistry》2002,41(31):9900-9910
The localization of Mn(2+) in A-tract DNA has been studied by (1)H NMR spectroscopy using a series of self-complementary dodecamer oligonucleotides that contain the sequence motifs A(n)(n) and T(n)A(n), where n = 2, 3, or 4. Mn(2+) localization in the minor groove is observed for all the sequences that have been studied, with the position and degree of localization being highly sequence-dependent. The site most favored for Mn(2+) localization in the minor groove is near the 5'-most ApA step for both the T(n)A(n) and the A(n)T(n) series. For the T(n)A(n) series, this results in two closely spaced symmetry-related Mn(2+) localization sites near the center of each duplex, while for the A(n)T(n) series, the two symmetry-related sites are separated by as much as one half-helical turn. The degree of Mn(2+) localization in the minor groove of the T(n)A(n) series decreases substantially as the AT sequence element is shortened from T(4)A(4) to T(2)A(2). The A(n)T(n) series also exhibits length-dependent Mn(2+) localization; however, the degree of minor groove occupancy by Mn(2+) is significantly less than that observed for the T(n)A(n) series. For both A(n)T(n) and T(n)A(n) sequences, the 3'-most AH2 resonance is the least broadened of the AH2 resonances. This is consistent with the observation that the minor groove of A-tract DNA narrows in the 5' to 3' direction, apparently becoming too narrow after two base pairs for the entry of a fully hydrated divalent cation. The results that are reported illustrate the delicate interplay that exists between DNA nucleotide sequence, minor groove width, and divalent cation localization. The proposed role of cation localization in helical axis bending by A-tracts is also discussed.  相似文献   

18.
The paper is a review of the family-level classifications of the order Eumonostilifera. The elaboration of a phylogenetic system of Eumonostilifera is not yet possible. Some new groups, presumably monophyletic, have been distinguished, which are considered to be of a family rank (Neesiidae fam. n., Sacconemertidae stat. n., Zygonemertidae fam. n., Prostomatidae, Acteonemertidae fam. n., and Potamonemertidae fam. n.). The proposed system is a typological one; however, it can be used as a basis for further taxonomical and phylogenetic studies.  相似文献   

19.
The large genus Orthomorpha is rediagnosed and is shown to currently comprise 51 identifiable species ranging from northern Myanmar and Thailand in the Northwest to Lombok Island, Indonesia in the Southeast. Of them, 20 species have been revised and/or abundantly illustrated, based on a restudy of mostly type material; further 12 species are described as new: Orthomorpha atypicasp. n., Orthomorpha communissp. n., Orthomorpha isarankuraisp. n., Orthomorpha picturatasp. n., Orthomorpha similanensissp. n., Orthomorpha suberectasp. n., Orthomorpha tuberculiferasp. n.,Orthomorpha subtuberculiferasp. n. and Orthomorpha latitergasp. n., all from Thailand, as well as Orthomorpha elevatasp. n.,Orthomorpha spiniformissp. n. and Orthomorpha subelevatasp. n., from northern Malaysia. The type-species Orthomorpha beaumontii (Le Guillou, 1841) is redescribed in due detail from male material as well, actually being a senior subjective synonym of Orthomorpha spinala (Attems, 1932), syn. n. Two additional new synonymies are proposed: Orthomorpha rotundicollis (Attems, 1937) = Orthomorpha tuberculata (Attems, 1937), syn. n., and Orthomorpha butteli Carl, 1922 = Orthomorpha consocius Chamberlin, 1945, syn. n., the valid names to the left. All species have been keyed and all new and some especially widespread species have been mapped. Further six species, including two revised from type material, are still to be considered dubious, mostly because their paraterga appear to be too narrow to represent Orthomorpha species. A new genus, Orthomorphoidesgen. n., diagnosed versus Orthomorpha through only moderately well developed paraterga, coupled with a poorly bi- or trifid gonopod tip, with at least some of its apical prongs being short spines, is erected for two species: Orthomorpha setosus (Attems, 1937), the type-species, which is also revised from type material, and Orthomorpha exaratus (Attems, 1953), both comb. n. ex Orthomorpha.  相似文献   

20.
Karyological information about Iberian Genista species is limited because of their wide geographical distribution. It is a major factor in the understanding of a genus whose genetic evolution is mostly related to aneuploidy and euploidy. The chromosome numbers of the following taxa have been counted: G. carpetana subsp. carpetana (n = 20), G. cinerascens (n = 12), G. micrantha (n = 18), G. mugronensis subsp. rigidissima (n = 18), G. ramosissima (2n = 48) and G. tinctoria (n = 24). The previously-assumed uniformity of chromosome number (n = 24) for all the subspecies of G. cinerea is supported here by data from subspp. murcica and speciosa. In G. florida, a new chromosome number, n = 23, has been found for both subspecies (florida and polygaliphylla). A discussion of the discrepancies between these data and previous ones is included. A new level of ploidy has been found in G. tuurnefortii subsp. tournefortii (n = 32). The data stress the necessity of obtaining chromosomal information from a number of plants of a taxon before its characteristic number is clear, and indicate that more chromosomal data will help the understanding of the cytological diversity within taxa in Genista.  相似文献   

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