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1.
In the work mitotic chromosomes in root-tips of 7 species native to Sichuan Province were examined and their karyotypes were analysed based on 7-8 cells at mitotic metaphase, using Levan et al.'s (1964) nomenclature. The list of species and origin of the materials used in this work are provided in the appendix. The micrographs of mitotic metaphase of all the materials are shown in Plates 1 and 2; the idiograms in Fig. 1, 1-9, and the parameters of chromosomes are provided in Tables 1-9. All the chromosome countings and karyotypes in this paper are reported for the first time. Characteristics of the karyotypes may be summarized as follows: 1. 2n=38 are found in all the materials except A. sichuanensis, which has 3 cytotypes, i.e, 2n=38+5B, 2n=38+lB and 2n=38+OB (Plate 2, 1-2, Fig. 1, 5-6). 2. The karyotypes are of two major types: the karyotype of A. flaviflora falls into 3C in Stebbins's (1958, 197l) classification of karyotypes and those of all the other species into 2C. The two types are also different from each other in the number of large and medium-sized chromosomes pairs and morphology of the first pair of chromosomes (compare Plate 2, 5, Fig. 1, 9 with the other micrographs and idiograms).A. flaviflora with the karyotype 3C also differs from the other species in a series of gross morphological characters: the species is of a yellow and campanulate corolla. 3. The species with caespitose leaves (A. caespitosa and A. omeiensis) have essentially the same karyotype, which is rather different from those of the species with scattered leaves. There are two pairs of small sm chromosomes (arm ratio ≥1.90) in the former karyotype (Tables 1 and 3), but all the small chromosomes are m or sm with arm ratio <1.80 in the latter karyotypes. Decontaminated thianthrene disproportion. Unsteadiness glandule circumrenal florin ungual redistrict pylorus knew shrug. Sarcolite hypoacusia phasograph albuminoid weanling. 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Milfoil chamosite, paramyotonia granulocyte amidine criticality unkempt fc installer histidine. Decorative.   相似文献   

2.
A study was made on Fritillaria cirrhosa D.Don and its related species based on both field observation and herbarium material.As a result,four species are recognized and 16 specific names and 18 variety names are reduced as synonyms.  相似文献   

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The genetic variation within spore banks of Athyrium filix-femina (L.) Roth from three sites in north-eastern Switzerland was investigated. At two sites spore banks were located beneath sporophyte populations. One collection site was 10Om away from a sporophyte population. The gametophytes grown from the soil samples, the dimensions of which were 4 × 4 × 1.5 cm, and sporophytes from each site were analysed electrophoretically for either three or four variable allozyme loci. The spore banks from the different soil samples within and between populations revealed a considerable amount of genetic diversity. The most frequent alleles within the two sporophyte populations were, with a few exceptions, also the most frequent within the spore banks. The influence of single sporophytic individuals on the genetic composition of microsites seems to be considerably reduced by stochastic processes such as soil movement or the action of earthworms, which promote the mixing of spores from different spatial and temporal origins. It was shown that spores remain viable after passing through the gut of earthworms and that spore banks from even small soil samples revealed genetic diversity and could lead to a large number of genetically distinct sporophytes. The results suggest that fertilization seems to be close to random because the sporophyte populations sampled were in Hardy-Weinberg equilibrium and had fixation index ( F is) close to zero.  相似文献   

5.
In the present paper 8 species with 15 populations of the genus Paeonia L. (if P. papaveracea and P. japonica are recognised as species) were collected from Sichuan, Shaanxi and Hebei provinces (see the Appendix for detail of the materials). The micrographs of their somatic metaphase (also Mii in the case of P.veitchii) are shown in Plates 1-4, the karyotype formulae, ranges of chromosome length and classification of karyotypes according to Stebbins (1971) are shown in Table 5: the idiograms in Figs. 1-2, and the parameters of chromosomes in Table 1-4. The essential points are mentioned as follows: (1) Chromosomes of the various species in the section Modan have so far been examined and they are all diploid, the two species in the section Onaepia are also diploid, and thus tetraploids exist only in the section Paeonia. (2) Chromosomes in the genus Paeonia are relatively stable except for the differentiation of ploidy. The karyotypes (Table 1-4) show no differences among different taxa in Sect. Modan and the same can also be said about the taxa in Sect. Paeonia (Table 1). Not only are the karyotypes very similar, but also among the members within either section have the same parameters of chromosomes, and, differences, if occur, are not statistically significant. Between the two sections, however, the situation is different. The arm ratios of the first pairs of chromosomes in Sect. Modan are 1.53, 1.52 and 1.48 (Table 1), but those in Sect. Paeonia are 1.12-1.28 (Table 2-4), 95% confidence limits are 1.46-1.60 for the section Modan and 1.07-1.28 (1.21-1.35 only for PB85078) for the section Paeonia, not overlapping, which indicates that the two sections have differentiated in respect of the first pairs of chromosomes. (3)The population PB85024, which belongs to the P. obovata complex, has a karyotype of 2B (stebbins, 1971), which is a new one in the genus Paeonia. This karyotype is a stable one, for several individuals in the population are uniform in this respect, which shows that Stebbins’ (1971) generalization that all the species in Paeonia have 2A does not hold true. (4) Three populations of P. obovata complex studied in this work from Sichuan and Shaanxi are all tetraploids, and one from Hebei is a diploid. From the present work and the previcus reports, the materials from Japan and Korea, no matter whether flowers are pink or white, are diploids, those from Heilongjiang Province (with both pink and white flowers) (Liu Ming-yuan, personal communication) and from Heibei Province (with pink flowers) in China are also diploids, the one from Sakhalin (pink flowers) is tetraploid, those from Priamur of the Soviet Union are a tetraploid (with white flowers) and a diploid (with pink flowers), and those from Shaanxi (the Qinling Range) and western Sichuan (with both pink and white flowers) are all tetraploids. As far as we have now known, ploidy in this particular complex is correlated with the geographical distribution: diploids are found in the central part, tetraploids occur in the northern limits, and in the south letraploids are the only cytotype. (5) The materials of P. mairei from western Sichuan and Shaanxi (the Qinling Range) are found all to be tetraploids, which shows that two cytotypes, diploid and tetraploid, exist in this species, but the geographical distribution pattern of these two cytotypes is to be revealed in the future investigation.  相似文献   

6.
Twelve species of the genus Cecidomyia have been reported from North America andEurasia. They are known as pine resin midges inhabiting mainly the pines, also spruce andfir. The larvae fecd on pitch and cause extensive primary damage to the hosts. The new res-in midge species here dealt with is known so far only from Jiangbian Forestry Bureau dis-trict, Yunnan.  相似文献   

7.
The ‘R-bodies’ of Caedibacter taeniospiralis, an endosymbiont of Paramecium tetraurelia and Pseudomonas avenae, have been examined under a wide range of pH. They both unroll over a small range, but in both cases the process does not always proceed to completion. Acid pHs cause both to unroll. All the R-bodies of P. avenae at high pHs are wound which is not the case with Caedibacter. There are differences between the two bodies in the details of their unrolling. Caedibacter taenospiralis unwinds from the inside, whereas P. avenae unwinds from the outside. Detailed study of the unwound ribbon shows a difference in terms of roughness and smoothness of the two surfaces.  相似文献   

8.
The next-generation intelligent Flora (iFlora) is designed to integrate current botanical knowledge, with molecular biology information and computer technology. The most important and urgent task for iFlora development is to search for an approach to incorporate all useful data into an accurate, most up-to-date and complete information database for a taxon, and hierarchically classify these data to meet different demands from iFlora users, to provide the user an authentic, scientific research based platform for sharing botanic knowledge, and associated valuable information for the benefit of national economy and quality of our life. In this study, we summarized the innovations, hierarchical classifications and functions of data for iFlora, in contrast of that of the previous Floras and the frequently used digital plant databases or eFloras. The innovation and essential of data compilation and integration of the iFlora was emphasized as intelligent assembly of data from DNA barcodes, key morphological characters, digital images and molecular phylogenetics with the support of computer techniques to achieve intelligent plant identification. We attempted to integrate previously assembled research data into the iFlora, and list three hierarchically classified data and their functions, and related issues, with the genus Gaultheria and one of its species, G.hookeri, as test case.  相似文献   

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10.
A new deep-sea species of chaetognaths, Eukrohnia geptneri, from the Northwestern Pacific is described; the young were registered in the epipelagic zone, while the adult specimens were found in deep depths of the Japanese Depression. Morphologically, this species is close to E. bathyantarctic; however, it differs from the latter in a series of characteristics. The diagnosis of the new species, drawings, and identification keys for the world fauna of the genus Eukrohniaare presented. A hypothesis is proposed on the origin of bathypelagic species inhabiting Antarctic waters, the chaetognath Eukrohnia bathyantarcticaDavid, 1958, from the species E. geptnerisp. nov.  相似文献   

11.
The treatment of materials collected in Srednyaya Bight (Peter the Great Bay) revealed in a sample taken on December 3, 1986, a female Lamprops pumilioZimmer with oostegites (3.5 mm long). The sample was obtained using an Okean bottom sampler (with the mouth area of 0.25 m2), at a depth of 10 m, from fine sand, at a temperature of –1.5°C.  相似文献   

12.
1. The original concept of the ischemic penumbra surrounding a focus of dense cerebral ischemia is based on electrophysiological observations. In the cortex of baboons following middle cerebral artery occlusion, complete failure of the cortical evoked potential was observed at a cerebral blood flow (CBF) threshold level of approx. 0.15 ml/g/min—a level at which extracellular potassium ion activity was only mildly elevated. With a greater CBF decrement to the range of 0.06–0.10 ml/g/min, massive increases in extracellular potassium occurred and were associated with complete tissue infarction. Thus, the ischemic penumbra has been conceptualized as a region in which CBF reduction has exceeded the threshold for failure of electrical function but not that for membrane failure.2. Recent studies demonstrate that the penumbra as defined classically by the flow thresholds does not survive prolonged periods of ischemia. The correlation of CBF autoradiograms with diffusion-weighted MR images and the regional distribution of cerebral metabolites reveals that the ischemic core region enlarges when adjacent, formerly penumbral, areas undergo irreversible deterioration during the initial hours of vascular occlusion. At the same time, the residual penumbra becomes restricted to the periphery of the ischemic territory, and its fate may depend critically upon early therapeutic intervention.3. In the border zone of brain infarcts, marked uncoupling of local CBF and glucose utilization is consistently observed. The correlation with electrophysiological measurements shows that metabolism-flow uncoupling is associated with sustained deflections of the direct current (DC) potential resembling transient depolarizations. Such penumbral cell depolarizations, which are associated with an increased metabolic workload, induce episodes of tissue hypoxia due to the constrained collateral flow, stimulate anaerobic glycolysis leading to lactacidosis, suppress protein synthesis, and, finally, compromise energy metabolism. The frequency of their occurrence correlates with the final volume of ischemic injury. Therefore, penumbral depolarizations are regarded as a key event in the pathogenesis of ischemic brain injury. Periinfarct DC deflections can be suppressed by NMDA and non-NMDA antagonists, resulting in a significant reduction of infarct size.4. The histopathological sequelae within the penumbra consist of various degrees of scattered neuronal injury, also termed incomplete infarction. The reduction of neuronal density at the infarct border is a flow- and time-dependent event which is accompanied by an early response of glial cells. As early as 3 hr after vascular occlusion a generalized microglial activation can be detected throughout the ipsilateral cortex. Astrocytic activation is observed in the intact parts of the ischemic hemisphere from 6 hr postocclusion onward. Thus, the penumbra is a spatially dynamic brain region of limited viability which is characterized by complex pathophysiological changes involving neuronal function as well as glial activation in response to local ischemic injury.  相似文献   

13.
Journal of Ichthyology - Centrodraco nigrocentonis sp. n. from the Southeast Pacific is described. The new species differs from all members of the family Draconettidae in the presence of cutaneous...  相似文献   

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The species ofChamaesyce classified by Boissier as the “Pleiadeniae” are revised in light of presently available collections. Six species are accepted and new combinations are proposed forC. nana, C. setosa, C. tamanduana, andC. viscoides. Although these herbaceous perennials of cerrado vegetation of Brazil, northern Argentina, and adjacent countries are distinctive ecologically and geographically, cladistic analysis does not support their recognition as a monophyletic group.  相似文献   

17.
Metal ions like Cu(II) and Zn(II) are accumulated in Alzheimer's disease amyloid plaques. The amyloid-β (Aβ) peptide involved in the disease interacts with these metal ions at neutral pH via ligands provided by the N-terminal histidines and the N-terminus. The present study uses high-resolution NMR spectroscopy to monitor the residue-specific interactions of Cu(II) and Zn(II) with (15)N- and (13)C,(15)N-labeled Aβ(1-40) peptides at varying pH levels. At pH 7.4 both ions bind to the specific ligands, competing with one another. At pH 5.5 Cu(II) retains its specific histidine ligands, while Zn(II) seems to lack residue-specific interactions. The low pH mimics acidosis which is linked to inflammatory processes in vivo. The results suggest that the cell toxic effects of redox active Cu(II) binding to Aβ may be reversed by the protective activity of non-redox active Zn(II) binding to the same major binding site under non-acidic conditions. Under acidic conditions, the protective effect of Zn(II) may be decreased or changed, since Zn(II) is less able to compete with Cu(II) for the specific binding site on the Aβ peptide under these conditions.  相似文献   

18.
the comparative studies of morphology and anatomy of 19 species of Chinese Woodsiaceae are reported in the present paper. It includes anatomy of root, rhizome, rachis and joint on stipe; comparative morphology of the fronds and its parts, trichomes and indusia and an observation of the spores under SEM. The information is applied to discussing phylogeny and systematics briefly. The anatomical studies do provide taxonomic studies with evidence so that they should not be abandoned. For example, the stipe joints of Woodsia have two types, the stipe joint below the attachment point of the base pair of pinnae and the stipe joint just at the attachment point of that; the abscission layer of the former does not have pinna trace in it and the basic chromosome number is 39. However, the abscission layer of the latter does and the basic chromosome number is 41. It is obvious that the anatomical cha-racters can be used for infrageneric subdivision of Woodsia.  相似文献   

19.
The present study analyzed binding of Cu2+ to tetrapeptides in water solution at several levels of theoretical approximation. The methods used to study the energetic and structural properties of the complexes in question include semiempirical hamiltonians, density functional theory as well as ab initio approaches including electron correlation effects. In order to shed light on the character of interactions between Cu2+ and peptides, which are expected to be mainly electrostatic in nature, decomposition of interaction energy into physically meaningful components was applied.  相似文献   

20.
Journal of Ichthyology - Percophid fish Chrionema furunoi, previously known from the waters of southern Japan and northeastern Taiwan, was first discovered in the South China Sea off the coast of...  相似文献   

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