Molecular and morphological data suggest that Spinibarbus caldwelli (Nichols) (Teleostei : Cyprinidae) is a valid species

The taxonomic problem of the cyprinid species of genus Spinibarbus, occurring in southern China and northern Vietnam, was resolved on the basis of molecular and morphological analyses. Spinibarbus caldwelli and Spinibarbus hollandi have a smooth posterior edge of the last unbranched dorsal fin ray among species in the genus. Spinibarbus caldwelli is currently regarded as a junior synonym of S. hollandi because of ambiguities in diagnostic characters. In this article, 11 mtDNA cytochrome b sequences of Spinibarbus specimens were analyzed together with Barbodes gonionotus and Puntius conchonius as outgroups. Our results showed that specimens identified as S. hollandi from Taiwan were different from those from the Asian mainland at a high level of genetic divergence (0.097-0.112), which is higher than that between the two valid species, S. sinensis and S. yunnanensis ( 0.089), and suggested that Taiwan specimens should be considered as a different species from the Asian mainland one. In a molecular phylogenetic analysis, the sister-group relationship between Taiwan specimens and the Asian mainland specimens was supported strongly by a high confidence level ( 100% in bootstrap value). Further analysis of morphological characters showed that overlap of diagnostic characters is much weaker than previously suggested. Taiwan specimens had 8 branched rays in the dorsal fin, whereas those from the mainland had almost 9-10. The molecular and morphological differences suggest S. caldwelli to be valid. The molecular divergence shows the genetic speciation of S. hollandi and S. caldwelli might have occurred 5.6-4.9 million years ago; the former could be a relict species in Taiwan, and the latter dispersed in the Asian mainland.

Molecular and morphological analysis of endangered species Gymnodiptychus integrigymnatus (Teleostei: Cyprinidae)

Gymnodiptychus integrigymnatus is a critically endangered species endemic to the Gaoligongshan Mountains. It was thought to be only distributed in several headwater-streams of the Longchuanjiang River (west slope of the Gaoligongshan Mountains, belonging to the Irrawaddy River drainage). In recent years, dozens of G. integrigymnatus specimens have been collected in some streams on the east slope of the Gaoligongshan Mountains (the Salween drainage). We performed a morphological and genetic analyses (based on cytochrome b and D-loop) of the newly discovered populations of G. integrigymnatus to determine whether the degree of separation of these populations warrants species status. Our analysis from the cytochrome b gene revealed that nine individuals from the Irrawaddy drainage area and seven individuals from the Salween drainage area each have only one unique haplotype. The genetic distance between the two haplotypes is 1.97%. Our phylogenetic analysis revealed that G. integrigymnatus is closely related to highly specialized schizothoracine fishes. Analysis from the mitochondrial control region revealed that G. integrigymnatus has relatively high genetic diversity (pi was 0.00891 and h was 0.8714), and individuals from different river drainages do not share the same haplotypes. The AMOVA results indicated 87.27% genetic variability between the Salween and Irrawaddy populations. Phylogenetic trees show two major geographic groups corresponding to the river systems. We recommend that G. integrigymnatus should be considered as a high priority for protected species status in the Gaoligongshan Mountains National Nature Reserve, and that the area of the Gaoligongshan Mountains National Nature Reserve should be expanded to cover the entire distribution of G. integrigymnatus. Populations of G. integrigymnatus from different river systems should be treated as evolutionarily significant units.

High phosphorous doping and morphological evolution during Si growth by gas source molecular beam epitaxy (GSMBE)

Uniform and high phosphorous doping has been demonstrated during Si growth by GSMBE using disilane and phosphine. The p-n diodes, which consist of a n-Si layer and a p-SiGe layer grown on Si substrate, show a normal I-V characteristic. A roughening transition during P-doped Si growth is found. Ex situ SEM results show that thinner film is specular. When the film becomes thicker, there are small pits of different sizes randomly distributed on the flat surface. The average pit size increases, the pit density decreases, and the size distribution is narrower for even thicker film. No extended defects are found at the substrate interface or in the epilayer. Possible causes for the morphological evolution are discussed. (C) 1999 Elsevier Science B.V. All rights reserved.

Effect of gamma-ray radiation on physiological, morphological characters and chromosome aberrations of minitubers in Solanum tuberosum L.

Purpose: To investigate the effects of gamma-ray radiation on the physiological, morphological characters and chromosome aberrations of minitubers. Materials and methods: Minitubers of one potato cultivar, 'Shepody', were irradiated with 8 doses of gamma-rays (0, 10, 20, 30, 40, 50, 60, 70 and 80 Gy [Gray]) to investigate the effects of radiation on emergence ability, plant height and root length, morphological variations, chromosome aberrations, M-1 (first generation mutants) tuber number and size of minituber plants. Results: Compared with the non-irradiated controls, the whole period of emergence was prolonged by 10-15 days for minitubers treated with gamma-ray radiation, but low doses of radiation (10, 20 and 30 Gy) promoted the emergence percentage of minitubers. With an increase in radiation dose, the emergence percentage, plant height and root length of minituber plants were significantly inhibited at 40 and 50 Gy. No emergence occurred at 60 Gy and higher doses. After radiation, a series of morphological variations and chromosome aberrations appeared in minituber plants. Radiation with 20 Gy promoted tuber formation, and the average number and diameter of M-1 tubers per plant were significantly increased over the control by 71% and 34%, respectively. Conclusion: Low doses of radiation (10-30 Gy) might be used as a valuable parameter to study the improvement of minitubers by gamma-ray radiation treatment.

Phylogeny and biogeography of the Petaurista philippensis complex (Rodentia : Sciuridae), inter- and intraspecific relationships inferred from molecular and morphometric analysis

With modified DNA extraction and Purification protocols, the complete cytochrome b gene sequences (1140 bp) were determined from degraded museum specimens. Molecular analysis and morphological examination of cranial characteristics of the giant flying squirrels of Petaurista philippensis complex (P. grandis, P. hainana, and P. yunanensis) and other Petaurista species yielded new insights into long-standing controversies in the Petaurista systematics. Patterns of genetic variations and morphological differences observed in this study indicate that P. hainana, P. albiventer, and P. yunanensis can be recognized as distinct species, and P. grandis and P. petaurista are conspecific populations. Phylogenetic relationships reconstructed by using parsimony, likelihood, and Bayesian methods reveal that, with P. leucogenys as the basal branch, all Petaurista groups formed two distinct clades. Petaurista philippensis, P. hainana, P. yunanensis, and P. albiventer are clustered in the same clade, while P. grandis shows a close relationship to P. petaurista. Deduced divergence times based on Bayesian analysis and the transversional substitution at the third codon suggest that the retreating of glaciers and upheavals or movements of tectonic plates in the Pliocene-Pleistocene were the major factors responsible for the present geographical distributions of Petaurista groups. (c) 2005 Elsevier Inc. All rights reserved.

Spray combustion synthesis of nanocrystalline Y2O3 and its thermodynamical and morphological study

Nano Y2O3 particles with a spherical shape and narrow size distribution have been prepared by a novel spray combustion method. The experimental procedure is briefly described and the thermodynamical process of the post-heat treatment is investigated in this paper. The precursor fully crystallized when treated at as low as 400 degrees C. Prepared particles showed spherical shape and well dispersibility under different treating conditions. Narrow size distribution of particles was achieved even when the precursor was treated at 1373 K. (C) 2007 Elsevier B.V. All rights reserved.