共查询到20条相似文献,搜索用时 31 毫秒
1.
We have previously demonstrated that in A 6 renal epithelial cells, a commonly used model of the mammalian distal section of the nephron, adenosine A 1 and A 2A receptor activation modulates sodium and chloride transport and intracellular pH (Casavola et al., 1997). Here we show that
apical addition of the A 3 receptor-selective agonist, 2-chloro-N 6-(3-iodobenzyl)-adenosine-5′-methyluronamide (Cl-IB-MECA) stimulated a chloride secretion that was mediated by calcium- and
cAMP-regulated channels. Moreover, in single cell measurements using the fluorescent dye Fura 2-AM, Cl-IB-MECA caused an increase
in Ca 2+ influx. The agonist-induced rise in [Ca 2+]
i
was significantly inhibited by the selective adenosine A 3 receptor antagonists, 2,3-diethyl-4,5-dipropyl-6-phenylpyridine-3-thiocarboxylate-5-carboxylate (MRS 1523) and 3-ethyl 5-benzyl
2-methyl-6-phenyl-4-phenylethynyl-1,4-(±)-dihydropyridine-3,5-dicarboxylate (MRS 1191) but not by antagonists of either A 1 or A 2 receptors supporting the hypothesis that Cl-IB-MECA increases [Ca 2+]
i
by interacting exclusively with A 3 receptors. Cl-IB-MECA-elicited Ca 2+ entry was not significantly inhibited by pertussis toxin pretreatment while being stimulated by cholera toxin preincubation
or by raising cellular cAMP levels with forskolin or rolipram. Preincubation with the protein kinase A inhibitor, H89, blunted
the Cl-IB-MECA-elicited [Ca 2+]
i
response. Moreover, Cl-IB-MECA elicited an increase in cAMP production that was inhibited only by an A 3 receptor antagonist. Altogether, these data suggest that in A 6 cells a G
s
/protein kinase A pathway is involved in the A 3 receptor-dependent increase in calcium entry.
Received: 9 March 2000/Revised: 14 August 2000 相似文献
2.
Summary New cytological evidence supporting x = 5 as the basic chromosome number of the genus Zea has been obtained as a consequence of our analysis of the meiotic configurations of Zea mays ssp. mays, Z. diploperennis, Z. perennis and of four F 1 artificial interspecific hybrids. Z. mays ssp. mays (2n = 20) presents regular meiosis with 10 bivalents (II) and is considered here as a typical allotetraploid (A 2A 2B 2B 2). In Z. diploperennis (2n = 20) 10II are formed in the majority of the cells, but the formation of 1III + 8II + 1I or 1III + 711 + 3I in 4% of the cells would indicate its segmental allotetraploid nature (A 1A 1B 1B 1). Z. perennis (2n = 40) had 5IV + 10II in 55% of the cells and would be considered as an auto-allooctoploid (A 1A 1A' 1A' 1C 1C 1C 2C 2). Z. diploperennis x Z. mays ssp. mays (2n = 20) presents 10II in ca. 70% of the cells and no multivalents are formed. In the two 2n = 30 hybrids ( Z. mays ssp. mays x Z. perennis and Z. diploperennis x Z. perennis) the most frequent meiotic configuration was 5III + 5II + 5I and in 2n = 40 hybrid ( Z. diploperennis x Z. perennis) was 5IV + 10II. Moreover, secondary association was observed in the three abovementioned tetraploid taxa (2n = 20) where one to five groups of two bivalents each at diakinesis-metaphase I was formed showing the affinities between homoeologous genomes. The results, as a whole, can be interpreed by assuming a basic x = 5 in this polyploid complex. The main previous contributions that support this working hypothesis are reviewed and its phylogenetic implications studied are discussed. 相似文献
3.
Absorbance-temperature profiles have been determined for the following self-complementary oligonucleotides or equimolar paris of complementary oligonucleotides containing GC base pairs: A 2GCU 2, A 3GCU 3, A 4GCU 4, A 6CG + CGU 6, A 8CG + CGU 8, A 4G 2 + C 2U 4, A 5G 2 + C 2U 5, A 4G 3 + C 3U 4, and A 5G 3 + C 3U 5. In all cases cooperative melting transitions indicate double-helix formation. As was found previously, the stability of GC containing oligomer helices is much higher than that of AU helices of corresponding length. Moreover, helices with the same length and base composition but different sequences also have quite different stabilites. The melting curves were andlyzed using a zipper model and the thermodynamic parameters for the AU pairs determined previously. The effect of single-strand stacking was considered separately. According to this model, the formation of a GC pair from unstacked single strands is associated with an ethalpy change of ?15 kcal/mole. Due to the high degree of single-strand stacking at room temperature the enthalpy change for the formation of GC pairs from unstacked single strands is only ?5 to ?6 kcal/mole. (The corresponding parameters for AU pairs are ?10.7 kcal/mole and ?5 to ?6 kcal/mole.) The sequence dependence of helix stability seems to be primarily entropic since no differences in Δ H were seen among the sequence isomers. The kinetics of helix formation was investigated for the same molecules using the temperature jump technique. Recombination of strands is second order with rate constants in the range of 10 5 to 10 7M?1 sec ?1 depending on the chain length and the nucleotide sequence. Within a series of oligomers of a given type, the rates of recombination decrease with increasing chain length. Oligomers with the sequence A nGCU n recombine six to eight times slower than the other oligomers of corresponding chain length. The experimental enthalpies of activation of 6 to 9 kcal/mole suggest a nucleation length of one or two GC base pairs. The helix dissociation process has rate constants between 0.5 and 500 sec ?1 and enthalpies of activation of 25 to 50 kcal/mole. An increase of chain length within a given nucleotide series leads to decreased rates of dissociation and increased enthalpies of activation. An investigation of the effect of ionic strength on A nGCU n helix formation showed that the rates of recombination increase considerably with increased ionic strength. 相似文献
4.
Both 6x Verbena aubletia ( n=15) and 2x V. tenuisecta ( n=5) form bivalents during meiosis, however, their 4x F 1 hybrid ( V. aubletia × V. tenuisecta) shows almost complete homoeologous pairing involving on average 19.74 out of its 20 chromosomes. In 10% cells there are 4IV+2II indicating that essentially there may be 4 homoeologous sets of 5 chromosomes each in the F 1 hybrid. Evidently, V. aubletia is segmental allo-hexaploid involving 3 homoeologous genomes (A 1A 1 A 2A 2 A 3A 3). Whether its cytologically diploid behaviour is the result of a multivalent suppressor system or due to an acute property of preferential pairing, cannot be answered with certainty. In either case intergenomal homoeologies are totally suppressed resulting in bivalent pairing, meiotic isolation of the 3 genomes and institution of normal fertility. 相似文献
5.
Spatial distribution of ectomycorrhizae-associated basidiomycetes was determined in oakbirch forest using terminal restriction
fragment length polymorphism (T-RFLP) analysis. The data were correlated with actual soil humidity, pH, electric conductivity
of the soil extract, absorbance A
465 and A
665 of water and alkali soil extracts and with the ratio A
465/ A
665 (parameter A4/A6). Natural non-homogeneity of the soil parameters was used as experimental gradient. Distance-based redundancy
analysis of the T-RFLP data (with soil parameters being taken as environmental parameters) provided significant results when
ITS1F-terminanted restriction fragments were analyzed. Among other fungi, a Mycena galericulata related fungus was observed to correlate negatively with A4/A6, indicating its association with highly humified soil organic
matter. Positive association of other, unidentified fungi with A4/A6 was also observed. Several other unidentified fungi negatively
correlated with electric conductivity of the soil extract. The results may explain nonhomogeneity of the spatial distribution
of the fungi associated with ectomycorrhizae as a result of their interaction with non-homogeneous soil environment. 相似文献
6.
Summary
Hordeum vulgare L. (2n=2x=14) was hybridized with Elymus patagonicus Speg. (2n=6x=42). The hybrid had 28 chromosomes, genomically represented as HSH 1H 2, and was perennial with a codominant phenotype. The chromosomes were meiotically associated as 19.6 univalents + 0.004 ring bivalents + 2.6 rod bivalents + 0.8 trivalents + 0.14 quadrivalents in 1,129 meiocytes, with a chiasma frequency of 4.77 per cell. The bivalent pairing presumably is an autosyndetic but modified expression of the H 1H 2 genomes of E. patagonicus, since ring bivalents were rare. This does not preclude the association of the H. vulgare H genome chromosomes with either H 1 and/or H 2 genomes of E. patagonicus to form bivalent or multivalent associations. A further evaluation of the genome homologies of H. vulgare, H. bogdanii, E. canadensis and E. patagonicus is proposed. 相似文献
7.
Summary The results presented indicate that the sex determination mechanism in the Texas race of R. hastatulus 2 n = 10 ( XX + 8 A); 2 n = 10 ( XX + 8 A)] is intermediate between the X/Y and X/A systems. In this race, sex is determined to some extent by the X/A balance, but the Y chromosome also affects sex expression, maleness or intersexuality being correlated with different ratios of X and Y chromosomes.The results obtained for the Texas race are fully compatible with data presented by Smith (1963) for the North Carolina race [ 2 n = 8 ( XX + 6 A); 2 n = 9 ( XX
1
Y
2 + 6 A)]. It may be concluded that evolution of the karyotype in this species is not accompanied by changes in the mechanism of sex determination. 相似文献
8.
Forty-three association (similarity) coefficients were collected and evaluated in this survey. Some of them are synonyms or direct correlates with earlier described indices (A 8, A 9, A 12, A 31, A 33), others are mere transforms from one range of values to another (A 10, A 24, A 33). Several coefficients are incompatible with suggested admissibility conditions of the minimum-maximum value (A 13, A 16, A 27, A 28, A 29, A 31), symmetry (A 1, A 2, A 13, A 16, A 26), discrimination between positive and negative association (A 27, A 28, A 31) or monotonicity with (χ 2) (A 19, to A 24); A 17 yields very low and erratic values. As a result, 23 coefficients were excluded and the remaining 20 measures were subjected to an empirical trial on interspecific association data among fungi of the genus Chaetomium, with the use of a cluster analysis. The classification produced five main clusters of related coefficients, with several subgroups. It was then demonstrated that representative indices from different clusters yield different dendrograms of interspecific association among Chaetomium, and A 34, A 14, possibly also A 36 and A 40 seemed to be less sensible. A set of measures that generally work well (at least in the interspecific association) comprises A 4 (Jaccard), A 4 (Dice-Sφrensen), A 7 (Kulczyński), A 11 (Driver-Kroeber-Ochiai) and, with some reservation A 30 (Pearson tetrachoric) and A 32 (Baroni-Urbani-Buser). For some purposes, however, other ‘admissible’ coefficients would be more optimal, and the choice of a measure should be related to the nature of the data. It is tentatively suggested that three or so alternative coefficients be used and the results compared on the same data basis; moreover, significance tests on association should be carried out whenever possible. 相似文献
9.
The osmotic pressure equation for nonideal, associating systems of the type nA + mB ? A nB m, has been derived, by using the assumption yA nB m/ yA nyB m = 1. This treatment can also be applied to related associations such as nA + mB ? AB + AB 2 + A 2B + …. From osmotic pressure experiments on the pure reactants it is possible to obtain the molecular weights ( MA and MB) of the reactants and also the virial coefficients (B AA and B BB) of the reactants. The osmotic pressure of a nonreacting mixture of A and B can be calculated from these measurements. It can be used along with osmotic pressure measurements on equilibrium mixtures of A and B to obtain expressions containing the equilibrium constant (or constants) and the cross-virial coefficients (B AB and B BA). Several procedures are described for the evaluation of the equilibrium constant (or constants) and the B AB or B BA terms. It appears that this procedure is a general one which is applicable to associations of the type nA + mB ? AB + A 2B + AB 2 + …. By correcting for nonideal behavior, one should then be able to apply it to any method available for analyzing ideal associations of the types considered here. In addition it is possible, subject to certain restrictions, to analyze associations of the type 3A + B ? A 2 + AB. 相似文献
10.
The effects of the selective adenosine (ADO) A 3receptor agonist IB-MECA ( N6-(3-iodobenzyl)adenosine-5′- N-methylcarboxamide) on cultured newborn rat cardiomyocytes were examined in comparison with ADO, the ADO A 1receptor-selective agonist R-PIA ( N6- R-phenylisopropyladenosine), or the ADO A 3selective antagonist MRS 1191 (3-ethyl-5-benzyl-2-methyl-6-phenyl-4-phenylethynyl-1,4-(±)-dihydropyridine-3,5 dicarboxylate), using digital image analysis of Feulgen-stained nuclei. At high concentration, IB-MECA (10 μM ) and ADO (200 μM) induced apoptosis; however, R-PIA or MRS 1191 did not have any detectable effects on cardiac cells. In addition, DNA breaks in cardiomyocytes undergoing apoptosis following treatment by IB-MECA were identified in situusing the nick end labeling of DNA (“TUNEL”-like) assay. In the presence of 10 μM IB-MECA, disorder in the contraction waves appeared, and a decrease in the frequency of beats was observed. Analysis with light microscopy revealed that the number of contracting cells decreased in a concentration-dependent manner. The A 3receptor agonist IB-MECA caused an increase in intracellular free calcium concentration ([Ca 2+] i). The drug produced a rapid rise followed by a sustained increase in [Ca 2+] i, which lasted for 40–60 s. Finally, cessation of beating and Ca 2+transients were observed. Full recovery of contractile activity and rhythmical Ca 2+transients were observed 15–20 min after IB-MECA treatment. The induction of apoptosis in the cardiocytes by IB-MECA led to the appearance of features of apoptotic nuclei: the onset of condensation, compacting, and margination of nuclear chromatin. These effects were accompanied by the disintegration of the structural framework of the nucleus and nuclear breakdown. The results suggest that activation of the A 3adenosine receptor may participate in the process of apoptosis in cardiomyocytes. 相似文献
11.
The effect of adenosine regulation on sodium and chloride transport was examined in cultured A 6 renal epithelial cells. Adenosine and its analogue N 6-cyclopentyladenosine (CPA) had different effects on short-circuit current ( I
sc) depending on the side of addition. Basolateral CPA addition induced an approximately threefold increase of the I
sc that reached a maximum effect 20 min after addition and was completely inhibited by preincubation with either an A 2 selective antagonist, CSC, or the sodium channel blocker, amiloride. Apical CPA addition induced a biphasic I
sc response characterized by a rapid fourfold transient increase over its baseline followed by a decline and a plateau phase
that were amiloride insensitive. The A 1 adenosine antagonist, CPX, completely prevented this response. This I
sc response to apical CPA was also strongly reduced in Cl −-free media and was significantly inhibited either by basolateral bumetanide or apical DPC preincubation. Only basolateral
CPA addition was able to induce an increase in cAMP level. CPA, added to cells in suspension, caused a rapid rise in [Ca 2+]
i
that was antagonized by CPX, not affected by CSC and prevented by thapsigargin preincubation. These data suggest that basolateral
CPA regulates active sodium transport via A 2 adenosine receptors stimulating adenylate cyclase while apical CPA regulates Cl − secretion via A 1 receptor-mediated changes in [Ca 2+]
i
. 相似文献
12.
Summary Divalent cation association to sonicated phospholipid liposomes has been examined with electron paramagnetic spectroscopy. Spectra were obtained suggesting that, in some cases, divalent cations associated with acidic phospholipid head groups are highly mobile.Using the amplitude of its characteristic sextet signal as a measure of free Mn(H 2O)
6
++
, the apparent affinities of cardiolipin and phosphatidylserine for Mn 2+ were measured as a function of monovalent electrolyte. Monovalent cations having smaller nonhydrated radii were more effective in displacing Mn from the phospholipids. Under conditions of low divalent cation concentrations, it is shown that the Gouy-Chapman diffuse double layer theory predicts a Mn-affinity ( K
A
) inversely proportional to the square of monovalent salt concentration. Although this relationship was closely obeyed for Mn binding to cardiolipin, the fall-off in K
A
with added sodium chloride was slower in the cases of Mn binding to phosphatidylserine or phosphatidic acid.When phosphatidylcholine or cholesterol was incorporated into mixed vesicles along with a fixed amount of charged phospholipid, the Mn-binding strength was roughly proportional to the weight fraction of the latter. This result is consistent with: (1) a random dispersal of lipids in the bilayer, and (2) a 1:2 divalent cation-phospholipid interaction. 相似文献
13.
Genome analysis has been used to investigate the relationship of C. danica L. to the diploid and tetraploid species in the genus. The results of this analysis suggest that C. danica has the genomic constitution A 1
7 A 1
7 A 2
7 A 2
7 T 7 T 7. Both A 7 genomes in C. danica are segmentally differentiated from the A 7 genome in C. groenlandica L. and from the similar A 6 genomes in C. pyrenaica DC. and C. officinalis L. but, in hybrids, are capable of some pairing with these genomes. A 2
7 is more distantly related to A 7 and A 6 than is A 1
7 and in A 7 some of the differentiation has taken place by reciprocal translocations. A 1
7 and A 2
7 still retain enough homology for pairing between them. The T 7 genome has no homology with any of the A genomes but may be derived from an ancestral T 6 genome. 相似文献
15.
Previously, we have reported that the coronary reactive hyperemic response was reduced in adenosine A2A receptor-null (A2AAR?/?) mice, and it was reversed by the soluble epoxide hydrolase (sEH) inhibitor. However, it is unknown in aortic vascular response, therefore, we hypothesized that A2AAR-gene deletion in mice (A2AAR?/?) affects adenosine-induced vascular response by increase in sEH and adenosine A1 receptor (A1AR) activities. A2AAR?/? mice showed an increase in sEH, AI AR and CYP450-4A protein expression but decrease in CYP450-2C compared to C57Bl/6 mice. NECA (adenosine-analog) and CCPA (adenosine A1 receptor-agonist)-induced dose-dependent vascular response was tested with t-AUCB (sEH-inhibitor) and angiotensin-II (Ang-II) in A2AAR?/? vs. C57Bl/6 mice. In A2AAR?/?, NECA and CCPA-induced increase in dose-dependent vasoconstriction compared to C57Bl/6 mice. However, NECA and CCPA-induced dose-dependent vascular contraction in A2AAR?/? was reduced by t-AUCB with NECA. Similarly, dose-dependent vascular contraction in A2AAR?/? was reduced by t-AUCB with CCPA. In addition, Ang-II enhanced NECA and CCPA-induced dose-dependent vascular contraction in A2AAR?/? with NECA. Similarly, the dose-dependent vascular contraction in A2AAR?/? was also enhanced by Ang-II with CCPA. Further, t-AUCB reduced Ang-II-enhanced NECA and CCPA-induced dose-dependent vascular contraction in A2AAR?/? mice. Our data suggest that the dose-dependent vascular contraction in A2AAR?/? mice depends on increase in sEH, A1AR and CYP4A protein expression. 相似文献
16.
Observations like high Zn 2+ concentrations in senile plaques found in the brains of Alzheimer's patients and evidences emphasizing the role of Zn 2+ in amyloid- β (A β)-induced toxicity have triggered wide interest in understanding the nature of Zn 2+-A β interaction. In vivo and in vitro studies have shown that aggregation kinetics, toxicity, and morphology of A β aggregates are perturbed in the presence of Zn 2+. Structural studies have revealed that Zn 2+ has a binding site in the N-terminal region of monomeric A β, but not much is precisely known about the nature of binding of Zn 2+ with aggregated forms of A β or its effect on the molecular structure of these aggregates. Here, we explore this aspect of the Zn 2+-A β interaction using one- and two-dimensional 13C and 15N solid-state NMR. We find that Zn 2+ causes major structural changes in the N-terminal and the loop region connecting the two β-sheets. It breaks the salt bridge between the side chains of Asp 23 and Lys 28 by driving these residues into nonsalt-bridge-forming conformations. However, the cross- β structure of A β42 aggregates remains unperturbed though the fibrillar morphology changes distinctly. We conclude that the salt bridge is not important for defining the characteristic molecular architecture of A β42 but is significant for determining its fibrillar morphology and toxicity. 相似文献
17.
The underlying principles of binding equilibria of arsenazo III with Ca 2+ and Mg 2+ are presented. Ca 2+ and Mg 2+ can bind arsenazo III in several different protonated forms depending on pH. The binding affinities of these different protonated forms of arsenazo III with Ca 2+ increase in the order of H 4A 4- <H 3A 5- >H 2A 6- and with Mg 2+, H 4A 4- > H 3A 5- > H 2A 6-. Arsenazo III is not membrane bound. The sensitivity ratio of arsenazo III with Ca 2+ to arsenazo III with Mg 2+ is close to two orders of magnitude. Arsenazo III and its complexes are extremely sensitive to pH changes. With 5 μM arsenazo III, the minimum detectable amount of Ca 2+ can be as low as 0.08 μM. Contrary to current belief, we found that Mg 2+ can bind to arsenazo III in a slightly acidic medium. Potential applications of arsenazo III to the study of membrane Ca 2+ transport are also discussed. 相似文献
18.
The modulation of I
A
K + current by ten trivalent lanthanide (Ln 3+) cations spanning the series with ionic radii ranging from 0.99 ? to 1.14 ? was characterized by the whole-cell patch clamp
technique in bovine adrenal zona fasciculata (AZF) cells. Each of the ten Ln 3+s reduced I
A
amplitude measured at +20 mV in a concentration-dependent manner. Smaller Ln 3+s were the most potent and half-maximally effective concentrations (EC 50s) varied inversely with ionic radius for the larger elements. Estimation of EC 50s yielded the following potency sequence: Lu 3+ (EC 50= 3.0 μ m) ≈ Yb 3+ (EC 50= 2.7 μ m) > Er 3+ (EC 50= 3.7 μ m) ≥ Dy 3+ (EC 50= 4.7 μ m) > Gd 3+ (EC 50= 6.7 μ m) ≈ Sm 3+ (EC 50= 6.9 μ m) > Nd 3+ (EC 50= 11.2 μ m) > Pr 3+ (EC 50= 22.3 μ m) > Ce 3+ (EC 50= 28.0 μ m) > La 3+ (EC 50= 33.7 μ m).
Ln 3+s altered selected voltage-dependent gating and kinetic parameters of I
A
with a potency and order of effectiveness that paralleled the reduction of I
A
amplitude. Ln 3+s markedly slowed activation kinetics and shifted the voltage-dependence of I
A
gating such that activation and steady-state inactivation occurred at more depolarized potentials. In contrast, Ln 3+s did not measurably alter inactivation or deactivation kinetics and only slightly slowed kinetics of inactivated channels
returning to the closed state. Replacement of external Ca 2+ with Mg 2+ had no effect on the concentration-dependent inhibition of I
A
by Ln 3+s. In contrast to their action on I
A
K + current, Ln 3+s inhibited T-type Ca 2+ currents in AZF cells without slowing activation kinetics.
These results indicate that Ln 3+ modulate I
A
K + channels through binding to a site on I
A
channels located within the electric field but which is not specific for Ca 2+. They are consistent with a model where Ln 3+ binding to negative charges on the gating apparatus alters the voltage-dependence and kinetics of channel opening. Ln 3+s modulate transient K + and Ca 2+ currents by two fundamentally different mechanisms.
Received: 21 January 1997/Revised: 3 April 1998 相似文献
19.
AbstractThe noncovalent interactions of phytate (Phy 6-) with biogenic amines were studied potentiometrically in aqueous solution, at t= 25°C. Several species are formed in the different H+-Phy 6--amine (A) systems, which have the general formula A p(Phy)H q(12-q)-, with p ≤ 3 and 6 ≤ q ≤ 10. The stability of these species is strictly dependent on the charges involved in the formation equilibria. For the equilibrium pH iA i+ + H j(Phy) (12- j)- = A p(Phy)H q( 12q)-, (q = pi + j)we found the relationship log K= aζ (ζ is the charge product of reactants), where a= 0.35(0.03, valid for all the amines; this roughly indicates an average free energy contribution per bond -ΔG 0 = 4.0 ± 0.2 kJ mol -1. A slightly more sophisticated equation is also proposed for predicting the stability of these species. Owing to the quite high (partially protonated) phytate charge, the stability of A p(Phy)H q(12-q)- species is quite high, making phytate a strong amine sequestering agent in a wide pH range. 相似文献
20.
Results of hybridization studies among the 6 species of subgenus Diplothrix ( Zinnia-compositae) are reported. Also included are analyses of chiasmata frequency in the parental species and 2 diploid hybrids. Pairing relationships and chiasmata frequency of the chromosomes in the hybrids of the diploid species indicate their genomes are homologous. Analyses of F 2's of Z. juni-perifolia X acerosa (2 n) show that production of pigment in ray flowers, C, from Z. juniperifolia segregates as a simple dominant over colorless, cc, from Z. acerosa. Morphological studies of the hybrids produced to date indicate that the origin of the polyploid taxa has been more circuitous than simple hybridization followed by chromosome doubling. The genomic constitution of Z. juniperifolia is designated A 1A 1, that of Z. acerosa A 2A 2, and that of Z. oligantha A 3A 3. Morphological data and chromosomal pairing in the polyploid hybrids suggest that the tetraploid species should be tentatively assigned genomic formulae as follows: A 1A 1A 2A 2 or A 1A 1A 3A 3 for both Z. citrea, and Z. grandiflora, and A 2A 2A 3A 3 for 4 n Z. acerosa. 相似文献
|