Flying lemurs – The 'flying tree shrews'? Molecular cytogenetic evidence for a Scandentia-Dermoptera sister clade

Background: Flying lemurs or Colugos (order Dermoptera) represent an ancient mammalian lineage that contains only two extant species. Although molecular evidence strongly supports that the orders Dermoptera, Scandentia, Lagomorpha, Rodentia and Primates form a superordinal clade called Supraprimates (or Euarchontoglires), the phylogenetic placement of Dermoptera within Supraprimates remains ambiguous. Results: To search for cytogenetic signatures that could help to clarify the evolutionary affinities within this superordinal group, we have established a genome-wide comparative map between human and the Malayan flying lemur (Galeopterus variegatus) by reciprocal chromosome painting using both human and G. variegatus chromosome-specific probes. The 22 human autosomal paints and the X chromosome paint defined 44 homologous segments in the G. variegatus genome. A putative inversion on GVA 11 was revealed by the hybridization patterns of human chromosome probes 16 and 19. Fifteen associations of human chromosome segments (HSA) were detected in the G. variegatus genome: HSA1/3, 1/10, 2/21, 3/ 21, 4/8, 4/18, 7/15, 7/16, 7/19, 10/16, 12/22 (twice), 14/15, 16/19 (twice). Reverse painting of G. variegatus chromosome-specific paints onto human chromosomes confirmed the above results, and defined the origin of the homologous human chromosomal segments in these associations. In total, G. variegatus paints revealed 49 homologous chromosomal segments in the HSA genome. Conclusion: Comparative analysis of our map with published maps from representative species of other placental orders, including Scandentia, Primates, Lagomorpha and Rodentia, suggests a signature rearrangement (HSA2q/21 association) that links Scandentia and Dermoptera to one sister clade. Our results thus provide new evidence for the hypothesis that Scandentia and Dermoptera have a closer phylogenetic relationship to each other than either of them has to Primates.

A correlation between radiation sensitivity and initial chromatid breaks in cancer cell lines revealed by Calyculin A-induced premature condensation

Three human malignancy cell lines were irradiated with Co-60 gamma-rays. Initial chromatid breaks were measured by using the chemically induced premature chromosome condensation technique. Survival curves of cells exposed to gamma rays was linear-quadratic while the efficiency of Calyculin A in inducing PCC of G(2) PCC was about five times more than G(1) PCC. A dose-dependent increase in radiation-induced chromatid/isochromatid breaks was observed in G(1) and G(2) phase PCC and a nearly positive linear correlation was found between cell survival and chromatin breaks. This study implies that low LET radiation-induced chromatid/isochromatid breaks can potentially be used to predict the radiosensitivity of tumor cells either in in vitro experimentation or in in vivo clinical radiotherapy.

Chromatid-type aberrations following irradiation in G0 lymphocytes with heavy ions

We describe a low level of chromatid-type aberrations which included the relatively rare isochromatid/chromatid triradial in peripheral blood lymphocytes that were irradiated, ostensibly in GO, with accelerated heavy C-12 ions. These were produced only at the energies of 69 MeV/n (34.6 keV/ mu m), almost absent at the energy of either 58.6 McV/n (46.07 keV/mu m) or 19.3 MeV/n (97 keV/mu m), nor were they found after low-LET X-rays. Mechanisms potentially responsible for their formation are discussed.

Correlation between initial chromatid damage and survival of various cell lines exposed to heavy charged particles

The biophysical characteristics of heavy ions make them a rational source of radiation for use in radiotherapy of malignant tumours. Prior to radiotherapy treatment, a therapeutic regimen must be precisely defined, and during this stage information on individual patient radiosensitivity would be of very great medical value. There are various methods to predict radiosensitivity, but some shortfalls are difficult to avoid. The present study investigated the induction of chromatid breaks in five different cell lines, including one normal liver cell line (L02), exposed to carbon ions accelerated by the heavy ion research facility in Lanzhou (HIRFL), using chemically induced premature chromosome condensation (PCC). Previous studies have reported the number of chromatid breaks to be linearly related to the radiation dose, but the relationship between cell survival and chromatid breaks is not clear. The major result of the present study is that cellular radiosensitivity, as measured by D-0, is linearly correlated with the frequency of chromatid breaks per Gy in these five cell lines. We propose that PCC may be applied to predict radiosensitivity of tumour cells exposed to heavy ions.

Survival and initial chromatid breakage in normal and tumour cells exposed in vitro to gamma rays and carbon ions at the HIRFL

Human hepatoma and normal liver cells were irradiated with C-12(6+) ion beams (linear energy transfer (LET) = 96 keV mu m(-1)) and gamma-rays at the Heavy Ion Research Facility in Lanzhou (HIRFL). The numbers and types of chromatid breaks were detected using the premature chromosome condensation technique. Irradiation with C-12(6+) ions produced a majority of isochromatid break types, while chromatid breaks were dominant for irradiation with gamma-rays. Experimental results showed that the initial level of chromatid breaks is clearly related to the absorbed dose from C-12(6+), ions and gamma-rays. The (12)C(6+)ions are relatively more effective at inducing initial chromatid breaks when compared with the gamma-rays. A relative biological effectiveness (RBE) of about 2.5 resulted for the induction of initial chromatid breaks by C-12(6+) ions relative to gamma-rays in both cell lines.

Molecular evidence for the sister relationship of the eastern Asia-North American intercontinental species pair in the Podophyllum group (Berberidaceae)

The presumed pair relationships of intercontinental vicariad species in the Podophyllum group (Sinopodophyllum hexandrum vs. Podophyllum pelatum and Diphylleia grayi vs. D. cymosa) were recently, considered to be paraphyletic. In the present paper, the trnL-F and ITS gene sequences of the representatives were used to examine the sister relationships of these two vicariad species. A heuristic parsimony analysis based on the trnLF data identified Diphylleia as the basal clade of the other three genera, but provided poor resolution of their inter-relationships. High sequence divergence was found in the ITS data. ITS1 region, more variable but parsimonyuninformative. has no phylogenetic value, Sequence divergence of the ITS2 region provided abundant, phylogenetically informative variable characters. Analysis of ITS2 sequences confirmeda sister relationship between the presumable vicariad species, in spite of a low bootstrap support for Sinopodophyllum hexandrum vs. Podophyllum pelatum. The combined ITS2 and trnL-F data enforced a sister relationship between Sinopodophyllum hexandrum and Podophyllum pelatum with an elevated bootstrap support of 100%. Based on molecular phylogeny, the morphological evolution of this group was discussed. The self-pollination might have evolved from cross-fertilization two times in this group. The different pollination and seed dispersal systems of Sinopodophyllum hexandrum and Podophlyllum pelatum resulted from their adaptations to different ecological habitats. The divergence time of Sinopodophyllum hexandrum-Podophyllum pelatum is estimated to be 6.52+/-1.89 myr based on the ITS divergence. The divergence of this species pair predated or co-occurred with the recent uplift of the Himalayas 4-3 myr during the late Miocene and the formation of the alpine habitats. Sinopodophyllum hexandrum developed a host of specialized characters in its subsequent adaptation to the arid alpine surroundings. The present study confirmed the different patterns of species relationship between Asian-North American disjuncts. The isolation of plant elements between North America and eastern Asia must have been a gradual process, resulting in the different phylogenetic patterns and divergence times of the disjuncts.

In the Far East : letters from Geraldine Guinness in China / edited by her sister.

http://www.archive.org/details/infareastletters00tayliala

The Bonds of Brotherhood: New Evidence of Sino-North Korean Exchanges, 1950-1954

Drawing on recently declassified documents from the archive of the Foreign Ministry of the People’s Republic of China (PRC), this article looks at China’s relationship with North Korea during and immediately after the Korean War. Although previous scholarship has touched on PRC–North Korean military ties during the war, this article is the first in-depth analysis of issues that are less well understood, notably China’s efforts to cope with a huge influx of refugees from North Korea, the PRC’s economic assistance during the war and in the early postwar reconstruction, and Chinese educational and ideological support for North Korean professionals and party cadres. The article shows that the extensive military coordination between Beijing and Pyongyang was only one way in which the war brought North Korea and the PRC into a closer relationship