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1.

Background

A healthy human can produce over 1?×?1015 blood cells throughout their life. This remarkable amount of biomass requires a concomitantly vast amount of iron to generate functional haemoglobin and functional erythrocytes.

Scope of the review

Erythroblasts form multicellular clusters with macrophages in the foetal liver, bone marrow and spleen termed erythroblastic islands. How the central erythroblastic island macrophage co-ordinates the supply of iron to the developing erythroblasts will be a central focus of this review.

Major conclusion

Despite being studied for over 60?years, the mechanisms by which the erythroblastic island niche serves to control erythroid cell iron metabolism are poorly resolved.

General significance

Over 2 billion people suffer from some form of anaemia. Iron deficiency anaemia is the most prevalent form of anaemia. Therefore, understanding the processes by which iron is trafficked to, and metabolised in developing erythrocytes, is crucially important.  相似文献   

2.
The Pacific Ocean evolved from the Panthalassic Ocean that was first formed ca 750 Ma with the rifting apart of Rodinia. By 160 Ma, the first ocean floor ascribed to the current Pacific plate was produced to the west of a spreading centre in the central Pacific, ultimately growing to become the largest oceanic plate on the Earth. The current Nazca, Cocos and Juan de Fuca (Gorda) plates were initially one plate, produced to the east of the original spreading centre before becoming split into three. The islands of the Pacific have originated as: linear chains of volcanic islands on the above plates either by mantle plume or propagating fracture origin, atolls, uplifted coralline reefs, fragments of continental crust, obducted portions of adjoining lithospheric plates and islands resulting from subduction along convergent plate margins. Out of the 11 linear volcanic chains identified, each is briefly described and its history summarized. The geology of 10 exemplar archipelagos (Japan, Izu-Bonin, Palau, Solomons, Fiji, New Caledonia, New Zealand, Society, Galápagos and Hawaii) is then discussed in detail.  相似文献   

3.
CpG islands (CGIs) play a fundamental role in genome analysis and annotation, and contribute to improving the accuracy of promoter prediction. Besides, CGIs in promoter regions are abnormally methylated in cancer cells and thus can be used as tumor markers. However, current methods for identifying CGIs suffer from various drawbacks. We present a new algorithm for detecting CGIs, called CpG Island Finder (CpGIF), which combines the best features in the most commonly used algorithms and avoids their disadvantages as much as possible. Five public tools for CpG island searching are used to compare with CpGIF for the assessment of accuracy and computational efficiency. The results reveal that CpGIF has higher performance coefficient and correlation coefficient than these previous methods, which indicates that CpGIF is able to provide high sensitivity and specificity at the same time. CpGIF is also faster than those methods with comparable prediction accuracy.  相似文献   

4.
Often unwittingly, scientific theory relies heavily upon literary metaphors which influence both the motives and the consequences of scientific endeavor. Human ecologists would do well to assess the implications of conventional metaphors which have been popular in traditional science, and to consider a newer picaresque mode better suited to the complexities of human ecology and to the temperament of modern consciousness.  相似文献   

5.
Understood in their historical context, current debates about psychiatric classification, prompted by the publication of the DSM‐5, open up new opportunities for improved translational research in psychiatry. In this paper, we draw lessons for translational research from three time slices of 20th century psychiatry. From the first time slice, 1913 and the publication of Jaspers' General Psychopathology, the lesson is that translational research in psychiatry requires a pluralistic approach encompassing equally the sciences of mind (including the social sciences) and of brain. From the second time slice, 1959 and a conference in New York from which our present symptom‐based classifications are derived, the lesson is that, while reliability remains the basis of psychiatry as an observational science, validity too is essential to effective translation. From the third time slice, 1997 and a conference on psychiatric classification in Dallas that brought together patients and carers with researchers and clinicians, the lesson is that we need to build further on collaborative models of research combining expertise‐by‐training with expertise‐by‐experience. This is important if we are to meet the specific challenges to translation presented by the complexity of the concept of mental disorder, particularly as reflected in the diversity of desired treatment outcomes. Taken together, these three lessons – a pluralistic approach, reliability and validity, and closer collaboration among relevant stakeholders – provide an emerging framework for more effective translation of research into practice in 21st century psychiatry.  相似文献   

6.
Relict floras of Atlantic islands: patterns assessed   总被引:2,自引:0,他引:2  
St. Helena (South Atlantic Ocean) and Macaronesia have endemic plants that have been interpreted as relicts. This paper divides these relicts into three main types. It is suggested that type 1 relicts are of Miocene age. They are usually wet tropical forest trees, geographically and taxonomically highly disjunct from their nearest relatives. Type 2 relicts are of Late Miocene or Pliocene age, usually trees of tropical or subtropical seasonally dry vegetation, often with trans-African disjunction, and moderate taxonomic isolation. Type 3 relicts are of Late Pliocene or Pleistocene age, usually herbs of arid zone or temperate vegetation, with little taxonomic or geographical disjunction from their nearest relatives. Relict theory is defined, with discussion of its explanatory power to account for patterns of endemism, and more generally, taxonomic and geographical patterns of biodiversity.  相似文献   

7.
Based on the distribution of 66 species of Mysidacea (Crustacea), a biogeographical analysis of the cold and temperate waters of the Southern Hemisphere was carried out. The expediency of separate division by pelagic and benthopelagic mysid faunas was supported. The original patterns of the division of Antarctic and subantarctic faunas are given. One biogeographical province and two subprovinces were distinguished by the fauna of pelagic mysids in the areas studied. Two biogeographical provinces and five subprovinces were distinguished by the fauna of benthopelagic mysids in the Antarctic and subantarctic.  相似文献   

8.
The genome of lethal animal pathogenic bacterium Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is characterized by the presence of multiple pathogenicity islands (PAIs). Computational methods have been developed to identify PAIs based on the distinguishing G + C levels in some PAI versus non-PAI regions. We observed that PAIs can have a very similar G + C level to that of the host chromosome, which may have led to false negative predictions using these methods. We have applied a novel method of genomic barcodes to identify PAIs. Using this technique, we have successfully identified both known and novel PAIs in the genomes of three strains of EHEC O157:H7.  相似文献   

9.
Hasan MS  Liu Q  Wang H  Fazekas J  Chen B  Che D 《Bioinformation》2012,8(4):203-205
Genomic Islands (GIs) are genomic regions that are originally from other organisms, through a process known as Horizontal Gene Transfer (HGT). Detection of GIs plays a significant role in biomedical research since such align genomic regions usually contain important features, such as pathogenic genes. We have developed a use friendly graphic user interface, Genomic Island Suite of Tools (GIST), which is a platform for scientific users to predict GIs. This software package includes five commonly used tools, AlienHunter, IslandPath, Colombo SIGI-HMM, INDeGenIUS and Pai-Ida. It also includes an optimization program EGID that ensembles the result of existing tools for more accurate prediction. The tools in GIST can be used either separately or sequentially. GIST also includes a downloadable feature that facilitates collecting the input genomes automatically from the FTP server of the National Center for Biotechnology Information (NCBI). GIST was implemented in Java, and was compiled and executed on Linux/Unix operating systems. AVAILABILITY: The database is available for free at http://www5.esu.edu/cpsc/bioinfo/software/GIST.  相似文献   

10.
11.
  • 1 Populations of wild goats that can be referred to as phenotypes of the pasang, or Bezoar goat, or wild goat Capra aegagrus Erxleben, 1777, still occur on several of the Mediterranean and Eastern Atlantic islands. Other populations became extinct not many decades ago.
  • 2 Fossil evidence for the natural spread of the wild goat to any of these islands has not been found. Originating in the Near East, the region of its natural range and its earliest domestication, the species was introduced by humans onto the Mediterranean islands starting as early as the Pre‐Pottery Neolithic.
  • 3 The islands of the Eastern Atlantic were colonized artificially by animals of ‘pre‐Hispanic’ origin. The principal phenotypes expressed by all these populations of goats can be matched with the characteristics of both C. a. aegagrus Erxleben, 1777 (aegagrus phenotype) and C. a. dorcas Reichenow, 1888 (dorcas phenotype).
  • 4 Most of these animals currently survive on the islands without being fed by humans, and should be protected.
  相似文献   

12.
13.
14.
A list of myxomycetes collected in Pantelleria, a volcanic island located 110 km southwest of the island of Sicily (Italy), is presented with data on distribution. Forty-nine taxa were identified, 38 of which are new for Sicily. The myxomycete diversity of Pantelleria was also compared with that of other volcanic islands located in the Atlantic and Pacific oceans.  相似文献   

15.
Using concepts of evolutionary game theory, this paper presents a critique of ethical intuitionism, or non-naturalism, in its cognitivist and objectivist interpretation. While epistemological considerations suggest that human rational learning through experience provides no basis for objective moral knowledge, it is argued below that modern evolutionary theory explains why this is so, i.e., why biological organisms do not evolve so as to experience objective preferences and obligations. The difference between the modes of the cognition of objective and of valuative environmental attributes is explained with reference to different modes of natural selection acting on the cognitive apparatus of the organism. The negative implications are pointed out which the observable diversity of intraspecific behavioural adaptations and of cultural values has for the cognitivist, objectivist foundation of ethics. Eventually a non-cognitivist alternative to ethical intuitionism is outlined in terms of empirical authority relations, with the ritualisation of dominance-submission patterns as the evolutionary origin of human charismatic authority.  相似文献   

16.
By their very nature oceanic island ecosystems offer great opportunities for the study of evolution and have for a long time been recognized as natural laboratories for studying evolution owing to their discrete geographical nature and diversity of species and habitats. The development of molecular genetic methods for phylogenetic reconstruction has been a significant advance for evolutionary biologists, providing a tool for answering questions about the diversity among the flora and fauna on such islands. These questions relate to both the origin and causes of species diversity both within an archipelago and on individual islands. Within a phylogenetic framework one can answer fundamental questions such as whether ecologically and/or morphologically similar species on different islands are the result of island colonization or convergent evolution. Testing hypotheses about ages of the individual species groups or entire community assemblages is also possible within a phylogenetic framework. Evolutionary biologists and ecologists are increasingly turning to molecular phylogenetics for studying oceanic island plant and animal communities and it is important to review what has been attempted and achieved so far, with some cautionary notes about interpreting phylogeographical pattern on oceanic islands.  相似文献   

17.
Mammals of Australian islands: factors influencing species richness   总被引:1,自引:0,他引:1  
Distribution patterns of indigenous non-volant terrestrial mammals on 257 Australian islands were examined in relation to environmental parameters and the effects of human-induced disturbance during prehistoric and historic times on island species numbers. Species occurrence for individual species, for taxonomic and trophic groups, and for all species together was related to environmental parameters using regression analysis and the extreme-value function model. Patterns of occurrence were examined separately within three major biogeographic regions derived by pattern analysis. The number of species known to have occurred on these islands during historic times was adequately predicted from area alone. No statistically significant improvement in predicted species number was gained by including island elevation, mean annual rainfall, isolation from the mainland or the number of potentially competing species present on the island. Similarly, no single factor other than area was found to influence consistently the presence of individual species. We conclude that the occurrence of indigenous non-volant terrestrial mammal species on these islands indicates a relictual rather than equilibrial fauna. Visitation by Aboriginal people during prehistoric times did not significantly increase mammal extinctions on islands. Examination of patterns of species richness for a given area on a regional basis showed that islands in and around Bass Strait and Tasmania (Bass Region) were the most species-rich, islands off the northern coasts were slightly less rich, and islands off the south western coasts had fewest species. This is in contrast to the usual latitudinal gradient in species richness patterns. However, islands off the northern and eastern coasts had an overall greater number of different species. When considered in relation to the number of different species of mammals occurring within each region, islands of a given size in Bass Region typically bore a higher proportion of this species pool than other regions. The Bass Region was found to be particularly rich in macropoid herbivores and dasyurid carnivores and insectivores. Analyses indicated that there is a very strong relationship between the presence of exotics as a whole and the local extinction of native mammals. Many mammal species formerly widespread on the Australian mainland are now restricted totally to islands (nine species) or are threatened with extinction on the mainland and have island populations of conservation significance (ten species). In all, thirty-five islands protect eighteen taxa of Australian threatened mammals. The land-use and management of these islands is of considerable importance to nature conservation. The introduction of exotic mammals to these islands should be prevented; any introductions that occur should be eradicated immediately.  相似文献   

18.
19.
Darwin visited c. 50 islands during the voyage of the Beagle , and from this, and his reading, was impressed by the difficulty of dispersal to oceanic islands, and the descent with modification shown by forms on such islands. He did not regard isolation as being a normal requisite for speciation. The general importance of this was not shown until the turn of the century.
In recent years studies on the Drosophilidae of Hawaii have allowed intensive genetical work to be started on the process of speciation. A quarter to one-third of the world species of Drosophila are Hawaiian endemics. These have evolved both elaborate courtship patterns, with associated bizarre morphological changes, and an apparently simple courtship pattern. This second line has apparently evolved into Scaptomyza on Hawaii. From there, Scaptomyza appears to have spread round the world, in the first instance largely to other oceanic islands.
Genetical studies on species on isolated islands are one of the most promising areas for investigating the importance of founder principle, and the processes of speciation.  相似文献   

20.
Nested species subsets are a common pattern of community assembly characteristic of many types of fragmented landscapes and insular systems. Here we describe nested subset patterns of amphibian and reptile occupancy on 23 forest islands in north-eastern Bolivia. We used observed occupancy patterns to differentiate five distributional guilds: widespread species, rare species, poor colonizers, area-sensitive species and supertramps. Amphibian occurrences were nested along a forest island isolation gradient, and when species from each of the distribution classes were removed from subsequent analyses of nestedness, we found that dispersal-limited poor colonizers were responsible for the association between nestedness and isolation. Amphibians associated with the grassland matrix at the study site showed a nested pattern linked with area, although this pattern did not scale up to all amphibians and could not be unequivocally attributed to any of the distributional guilds we recognized. There were no strong associations between two biological characteristics, body size and relative abundance in the matrix, and the likelihood of occupancy along either forest island area or isolation gradients. The relative importance of isolation in shaping nested patterns of amphibians on these forest islands may be a result of either (1) the greater range in isolation values included in this study compared with many others; (2) the long time since isolation in this landscape, manifesting a footprint of isolation not apparent in more recently fragmented patches; (3) the relatively homogeneous grassland matrix surrounding forest islands that likely provides little refuge for animals moving among forest islands.  相似文献   

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