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1.
The ground parrot (Pezoporus wallicus) has a coastal distribution in Victoria and has declined in range since European colonization. Its habitat consists of two major vegetation communities: coastal heathland and sedgeland. These are further divided into various sub-communities. These habitats contained high densities of cyperaceous and restionaceous plants, the seeds of which form the bulk of the bird's diet. Seeds and small fruits of some dicotyledonous plants and grasses are also eaten. Seed production by sedges remains fairly constant over time in sedgelands but varies in heathland, depending on time since burning. This variation is reflected by parallel changes in ground parrot population density. Both long unburnt and very frequently burnt heathlands are unsuitable for ground parrots. The birds also require dense vegetation cover. Ground parrots appear to live in territorial breeding pairs with enforced natal dispersal. This is an adaptation to an environment where habitat is patchily distributed in space and variable in quality over time.  相似文献   

2.
Melo M  O'Ryan C 《Molecular ecology》2007,16(8):1673-1685
The range of the grey parrot (Psittacus erithacus), one of the most heavily harvested bird species for the international pet trade, spans the forest belt of Central and West Africa and includes the oceanic island of Príncipe (Gulf of Guinea). Morphological variation led to the recognition of two mainland subspecies (P. e. erithacus and P. e. timneh). The population from Príncipe was originally described as a separate species (P. princeps) but is currently included in the nominate race. We used 1932 bp of the mitochondrial genome to clarify the genealogical affinities between the two currently-recognized mainland subspecies and the Príncipe population. Sampling included 20 individuals from Príncipe, 17 from P. e. erithacus, and 13 from P. e. timneh. We found that the two mainland subspecies form two independent lineages, having diverged up to 2.4 million years ago (Ma), and that the Príncipe population is composed of two lineages that diverged in allopatry. The most common lineage is descended from the first colonizers and evolved in isolation for up to 1.4 Ma. Contrary to current understanding, this 'Príncipe lineage' is more closely related to the timneh than to the erithacus subspecies. The second lineage consists of P. e. erithacus birds from the nearby mainland that colonized the island in recent times. The evolutionary dynamics of the grey parrot population of Príncipe are primarily characterized by isolation, with new genetic variation being added through rare immigration events. The heavily harvested Príncipe grey parrot population should therefore be treated as an independent conservation unit.  相似文献   

3.
《Inorganica chimica acta》1986,114(2):141-144
The preparations and properties of tris(dipivaloylmethanato)technetium(III), tris(trifluoroacetylacetonato)technetium(III), and tris(hexafluoroacetonato)technetium(III) are described. The oxidation of the dipivaloyl derivative to tris(dipivaloyl)technetium(IV) hexafluorophosphate was shown to take place readily. Voltammetric studies and magnetic resonance results on the new complexes are reported. The large shifts observed for the complexes seem to be due to a contact interaction.  相似文献   

4.
Boron is an essential nutrient for plants, but it is toxic in excess. Transgenic rice plants expressing an Arabidopsis thaliana borate efflux transporter gene, AtBOR4, at a low level exhibited increased tolerance to excess boron. Those lines with high levels of expression exhibited reduced growth. These findings suggest a potential of the borate transporter BOR4 for the generation of high-boron tolerant rice.  相似文献   

5.
(±)-Homosarkomycin (2) and (±)-rosaprostol (3) were synthesized from (±)-methyl 2-oxo-bicyclo[3.1.0]hexane-1-carboxylate (1) by using the nucleophilic ring opening reaction on the double-activated cyclopropane ring as the key step.  相似文献   

6.
(±)-Lamprolobine, the (+)-enatiomer of which was isolated from the leaves of Lamprolobium fruticosum, and (±)-epilamprolobine were synthesized from δ-valerolactam.  相似文献   

7.
The equimolar reaction of a β-diketiminate lithium salt LLi(OEt2) [L = HC(CMeNAr)2; Ar = 2,6-iPr2C6H3] with either GeBr2 or SnBr2 in diethyl ether affords the synthetically useful monomeric β-diketiminate-element halides LGeBr (1) and LSnBr (2), respectively. Both are soluble in hydrocarbon solvents, stable in inert atmosphere, and have been characterized by elemental analysis, NMR spectroscopy, and single-crystal X-ray diffraction analysis.  相似文献   

8.
(±)-Licarin A (1) was obtained by oxidative coupling, and its enantiomers, (?)-licarin A (2) and (+)-licarin A (3), were resolved by chiral HPLC. Schistosomicidal and trypanocidal activities of these compounds were evaluated in vitro against Schistosoma mansoni adult worms and trypomastigote forms of Trypanosoma cruzi. The racemic mixture (1) displayed significant schistosomicidal activity with an LC50 value of 53.57 μM and moderate trypanocidal activity with an IC50 value of 127.17 μM. On the other hand, the (?)-enantiomer (2), displaying a LC50 value of 91.71 μM, was more active against S. mansoni than the (+)-enantiomer (3), which did not show activity. For the trypanocidal assay, enantiomer 2 showed more significant activity (IC50 of 23.46 μM) than enantiomer 3, which showed an IC50 value of 87.73 μM. Therefore, these results suggest that (±)-licarin A (1) and (?)-licarin A (2) are promising compounds that could be used for the development of schistosomicidal and trypanocidal agents.  相似文献   

9.
Reaction of the ligand N-methyl-N-((6-pivaloylamido-2-pyridyl)methyl)-N-(2-pyridylethyl)amine (mpppa) with equimolar amounts of [Cu(H2O)6][ClO4]2 or CuCl2 · 2H2O in MeCN afforded mononuclear copper(II) complexes [Cu(mpppa)][ClO4]2 (1) and [Cu(mpppa)Cl2] (2). Crystal structure analysis reveals CuN3O (two pyridyl, an aliphatic amine, and an amide oxygen) coordination in 1 and CuN3Cl2 (two pyridyl, an aliphatic amine, and two chlorides) coordination in 2. Crystal packing diagram of 1 reveals that one of the perchlorate counteranions provides weak coordination to copper(II) centers and in turn the copper(II) centers assume pseudo-six-coordination, generating 1D chain. Notably, one of the copper(II)-coordinated chloride ions in 2 participates in an intramolecular N–H?Cl interaction. Intermolecular C–H?Cl interactions in the solid state generate helical structure. Spectroscopic (IR, UV–Vis, and EPR) and redox properties of the two complexes have been investigated and compared.  相似文献   

10.
(R)-(+)- and (S)-(?)-dihydrozeatins [(R)-(+)- and (S)-(?)-6-(4-hydroxy-3-methylbutylamino)purines, 1a and 1b] and their ribosides {(?)-6-[(R)-4-hydroxy-3-methylbutylamino]- and (?)-6-[(S)-4-hydroxy-3-methyl-butylamino]-9-β-D-ribofuranosylpurines, 3a and 3b} were synthesized and tested for their cytokinin activity by four bioassay systems, the growth of tobacco callus, the seed germination of lettuce, the fr. wt increase of excised radish cotyledons and the retardation of chlorophyll degradation in radish cotyledons. In tobacco callus bioassay, 1a was more active than 1b. The ribosides 3a and 3b were not less active than their corresponding aglycones 1a and 1b. In other bioassays used the activity followed the order: 1a >3a >1b >3b. In tobacco callus bioassay and lettuce seed germination, trans-zeatin [6-(4-hydroxy-3-methylbut-trans-2-enylamino)purine] showed stronger cytokinin activity than 1a.  相似文献   

11.
A novel synthesis of ( ± )-methyl epijasomonate (2) and the first synthesis of ( ± )-methyl cucurbate (4) were achieved starting from 2-allylcyclohexane-1,3-dione (8). The synthetic epimer 2 had a stronger jasmin flavor than the trans-isomer 1 with 95% purity.  相似文献   

12.
Methicillin-resistant Staphylococcus aureus (MRSA) has long been a common pathogen in healthcare facilities, but now, it has emerged as a problematic pathogen in the community setting as well. This study reported source, diagnosis and treatment of HA-MRSA and CA-MRSA.A total of sixty-five clinical samples (urine, pus, wound swab) were collected from clinical origin of Dhaka city, Bangladesh. All the isolates were tested phenotypically by conventional methods and genotypically by PCR targeting nuc, pvl and mecA genes. Finally sequencing was carried out for pvl gene to know the mutagenic variation or any amino acid changes in pvl gene. Chi square test was employed for statistical analysis. Patients of age group 51–60?years are more susceptible (46.15%) to MRSA, CA-MRSA or HA-MRSA infection. Female are (32.30%) more susceptible to MRSA infection. Among 65 isolates 53 isolates identified phenotypically as S. aureus. These were positive for amplification of nuc (270?bp) gene of S. aureus. Moreover, among 53 isolates 33 phenotypically considered as MRSA and 38 (72%) showed positive amplification for mecA (162?bp) gene. Among 38 MRSA isolates 22 (57.89%) confirmed as CA-MRSA and 16 (42.10%) as HA-MRSA. Finally, sequence analysis for lukS/F-PV genes from 4 representative isolates detected a new single nucleotide polymorphism in comparison with the control sequence. However, no amino acid changes were found. Statistical analysis showed HA-MRSA isolates were more commonly found in urine sample and CA-MRSA in pus and wound swab. CA-MRSA isolates were more resistant to tested antibiotics than HA-MRSA.  相似文献   

13.
Carbonyl sulfide (COS) and C(18)OO exchange by leaves provide potentially powerful tracers of biosphere-atmosphere CO(2) exchange, and both are assumed to depend on carbonic anhydrase (CA) activity and conductance along the diffusive pathway in leaves. We investigated these links using C(3) and C(4) plants, hypothesizing that the rates of COS and C(18)OO exchange by leaves respond in parallel to environmental and biological drivers. Using CA-deficient antisense lines of C(4) and C(3) plants, COS uptake was essentially eliminated and discrimination against C(18)OO exchange ((18)Δ) greatly reduced, demonstrating CA's key role in both processes. (18)Δ showed a positive linear correlation with leaf relative uptake (LRU; ratio of COS to CO(2) assimilation rates, A(s)/A(c), normalized to their respective ambient concentrations), which reflected the effects of stomatal conductance on both COS and C(18)OO exchange. Unexpectedly, a decoupling between A(s) and (18)Δ was observed in comparing C(4) and C(3) plants, with a large decrease in (18)Δ but no parallel reduction in A(s) in the former. This could be explained by C(4) plants having higher COS concentrations at the CA site (maintaining high A(s) with reduced CA) and a high phosphoenolpyruvate carboxylase/CA activity ratio (reducing (18)O exchange efficiency between CO(2) and water, but not A(s)). Similar A(s) but higher A(c) in C(4) versus C(3) plants resulted in lower LRU values in the former (1.16 ± 0.20 and 1.82 ± 0.18 for C(4) and C(3), respectively). LRU was, however, relatively constant in both plant types across a wide range of conditions, except low light (<191 μmol photon m(-2) s(-1)).  相似文献   

14.
15.
Abstract

The importance of the base composition and of the conformation of nucleic acids in the reaction with the drug cis-diamminedichloroplatinum(II) has been studied by competition experiments between the drug and several double-stranded polydeoxyribonucleotides. Binding to poly(dG)·poly(dC) is larger than to poly (dG-dC)·poly(dG-dC). There is no preferential binding in the competition between poly(dG-dC) ·poly(dG-dC), poly(dA-dC) ·poly(dG-dT) and poly(dA-dG)·poly(dC-dT). In the competition between poly(dG-dC) ·poly (dG-dC) (B conformation) and poly(dG-br5dC) ·poly(dG-br5dC) (Z conformation), the drug binds equally well to both polynucleotides. In natural DNA, modification of guanine residues in (GC)n·(GC)nsequences by the drug has been revealed by the inhibition of cleavage of these sequences by the restriction enzyme BssHII. By means of antibodies to platinated poly(dG-dC), it is shown that some of the adducts formed in platinated poly(dG-dC) are also formed in platinated pBR322 DNA. The type of adducts recognized by the antibodies is not known. Thin layer chromatography of the products after chemical and enzymatic hydrolysis of platinated poly(dG-dC) suggests that interstrand cross-links are formed. Finally, the conformations of poly(dG-m5dC) modified either by cis-diamminedichloroplatinum(II) or by trans-diammine- dichloroplatinum(II) have been compared by circular dichroism. Both the cis-isomer and the trans-isomer stabilize the Z conformation when they bind to poly(dG-m5dC) in the Z conformation. When they bind to poly(dG-m5dC) in the B conformation, the conformations of poly(dG-m5dC) modified by the cis or the trans-isomer are different. Moreover, the cis-isomer facilitates the B form-Z form transition of the unplatinated regions while the trans-isomer makes it more difficult.  相似文献   

16.
The He(I) and He(II) photoelectron spectra of a series of [(LL)M(CO)2] (LL = pyrrole-2-CHN′ R; R = t-Bu; M = Rh, Ir) complexes are reported. Assignments are proposed based on He(I)/He(II) intensity differences, on molecular orbital calculations of related complexes and of free ligands, and by comparison with the spectra of the free ligands Hpyrrole-2-CHN′t-Bu, Hpyrrole-2-carbaldehyde and Hpyrrole.The electronic structure of the complexes is discussed and conclusions are drawn about the metal-ligand interaction.  相似文献   

17.
18.
The physicochemical and biological properties of the new branched cyclomaltooligosaccharides (cyclodextrins; CDs), 2-O-α-D-galactosyl-cyclomaltohexaose (2-O-α-D-galactosyl-α-cyclodextrin, 2-Gal-αCD) and 2-O-α-D-galactosyl-cyclomaltoheptaose (2-O-α-D-galactosyl-β-cyclodextrin, 2-Gal-βCD), were investigated. The formation of inclusion complexes of 2-Gal-CDs with various kinds of guest compounds (clofibrate, cholesterol, cholecalciferol, digitoxin, digitoxigenin, and prostaglandin A(1)) was examined by a solubility method, and the results were compared with those of non-branched CDs and other 6-O-glycosyl-CDs such as 6-O-α-D-galactosyl-CDs, 6-O-α-D-glucosyl-CDs, and 6-O-α-maltosyl-CDs. The inclusion abilities of 2-Gal-αCD for clofibrate and prostaglandin A(1), and 2-Gal-βCD for clofibrate, cholecalciferol, cholesterol, and digitoxigenin were markedly weaker than those of non-branched CD and other 6-O-glycosyl-CDs in each series, probably because of a steric hindrance caused by the α-(1→2)-galactoside linkage. The hemolytic activities of 2-Gal-CDs on human erythrocytes were the lowest among each CD series, and the compounds showed negligible cytotoxicity towards Caco-2 cells up to at least 100mM.  相似文献   

19.
Summary A new strategy for stereoconservative and stereoselective syntheses of several types of amino acids starting from-functional carboxylic acids employing hexafluoroacetone as protecting and activating reagent is described. Outstanding features of this new method are the mild reaction conditions and the high yields for introduction and cleavage of the protective group allowing sensitive functional groups in the side chain to survive. Furthermore, the new concept results in saving of synthetic steps.  相似文献   

20.
Copper(II) ,-dicarboxylate complexes of general formulae, [Cu(O2C(CH2)nCO2)]·xH2O, [Cu(O2C(CH2)nCO2) (phen)2xH2O and [Cu(O2C(CH2)nCO2)(bipy)yxH2O (n=1–8; y=1, 2; phen = 1,10-phenanthroline; bipy = 2,2-bipyridine) were synthesised. These copper complexes, some related manganese(II) complexes and the metal-free ligands were screened in vitro for their ability to inhibit the growth of Candida albicans. Metal-free 1,10-phenanthroline and all of the copper(II) and manganese(II) phenanthroline complexes were potent growth inhibitors, with only one bipyridine complex, [Cu(O2C(CH2)CO2)(bipy)2]·2H2O, having moderate activity. The remaining substances were effectively inactive. Complexes which were active against C. albicans also proved effective against C. glabrata, C. tropicalis and C. kreusi with the manganese complexes retaining superior activity. For the phenanthroline complexes the active drug species is thought to be the dication [M(phen)2(H2O)n]2+ (M = Cu, Mn). Escherichia coli and Staphylococcus aureus were resistant to all of the metal complexes and also to metal-free 1,10-phenanthroline. Only the copper phenanthroline complexes showed intermediate activity against Pseudomonas aeruginosa.  相似文献   

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