A preliminary study on designing ecological corridors in Xishuangbanna National Nature Reserve with 3S techniques

This paper is based on the fieldwork in Xishuangbanna Natioanl Nature Reserve in Yunnan Province of China. GPS data of Asian elephants were collected and analyzed with the remote sensing satellite photos of the region to estimate the landform physiognomy of different colors. We also analyzed a series of ecological factors including altitude, landform, relief, villages and roads which affected the distribution and movement of Asian elephants. The results suggested the possibility of designing and establishing corridors in Xishuangbanna National Nature Reserve to protect the population of wild elephants in the region. __________ Translated from Journal of Beijing Normal University (Natural Science) 2006, 42(4): 405-C409 [译自: 北京师范大学学报 (自然科学版)]     

A preliminary study on designing ecological corridors in Xishuangbanna National Nature Reserve with 3S techniques

This paper is based on the fieldwork in Xishuang-banna Natioanl Nature Reserve in Yunnan Province of China. GPS data of Asian elephants were collected and analyzed with the remote sensing satellite photos of the region to estimate the landform physiognomy of different colors. We also analyzed a series of ecological factors includ-ing altitude, landform, relief, villages and roads which affected the distribution and movement of Asian elephants. The results suggested the possibility of designing and estab-lishing corridors in Xishuangbanna National Nature Reserve to protect the population of wild elephants in the region.     

Isolation and characterization of dinucleotide microsatellite loci in the Asian elephant (Elephas maximus)

The endangered Asian elephant is found today primarily in protected areas. We characterized 18 dinucleotide microsatellite loci in this species. Allelic diversity ranged from three to eight per locus, and observed heterozygosity ranged from 0.200 to 0.842 in a wild population. All loci were in Hardy-Weinberg equilibrium, but linkage disequilibrium was detected between two loci in the wild, but not in the zoo elephants. These loci will be useful for the population-level studies of this species.     

Morphological and genetic variation in the endangered Sulawesi tortoise Indotestudo forstenii: evidence of distinct lineages?

Limited fieldwork and anecdotal evidence indicate that allopatric populations of the endangered Sulawesi tortoise (Indotestudo forstenii) differ in size and presence/absence of a nuchal scute, suggesting that these may constitute separate evolutionary lineages. We examined morphological and genetic variation to determine if the nuchal scute is correlated with size or genetic divergence. Our results indicate a strong correlation between size and nuchal scute such that turtles lacking a nuchal scute were larger than those possessing a nuchal scute. However, we found no correlation between genetic divergence and presence/absence of nuchal scutes, and thus no evidence of genetically differentiated lineages.     

Extreme mtDNA homogeneity in continental Asian populations

Mitochondrial DNA (mtDNA) variation in continental Asia has not been well-studied. Here, we report mtDNA HV1 sequences for 84 Xi'an and 82 Changsha Han Chinese, 89 Honshu Japanese, and 35 Vietnamese. Comparison of these sequences with other Asian mtDNA sequences reveals high variability within populations, but extremely low differentiation among Asian populations. Correlations between genetic distance and geographic distance, based on mtDNA and Y chromosome variation, indicate a higher migration rate in females than in males. This may reflect patrilocality, as suggested previously, but another plausible hypothesis is that the demographic expansion associated with the spread of agriculture in Asia may be responsible for the extreme genetic homogeneity in Asia.     

A chimeric Plasmodium falciparum Pfnbp2b/Pfnbp2a gene originated during asexual growth

The Plasmodium falciparum line 3D7-A has an unusual invasion phenotype, such that it can invade enzyme-treated and mutant red blood cells that are resistant to invasion by other parasite lines. 3D7-A has a chimeric Pfnbp2b gene that contains part of the repeat region of the paralogous gene Pfnbp2a. This chimeric gene originated by spontaneous gene conversion during normal maintenance in culture, indicating that ectopic recombination and gene conversion during asexual growth are potentially important mechanisms participating in the evolution of paralogous genes in Plasmodium. However, the presence of the chimeric Pfnbp2b gene in 3D7-A was not associated with its peculiar invasion phenotype.     

Geochemical compositions of core sediments in eastern China: Implication for Late Cenozoic palaeoenvironmental changes

Three deep drill holes with depth exceeding 300 m were collected from eastern China for geochemical study in order to reconstruct Late Cenozoic palaeoenvironmental changes. The Late Cenozoic strata in eastern China are predominantly composed of lacustrine, fluvial and littoral sediments. Degrees of chemical weathering during the Late Cenozoic were estimated by using geochemical proxies including CaCO₃ contents, chemical index of alteration and Al₂O₃-CaO-(Na₂O + K₂O) diagrams. The results show that chemical weathering was intense in eastern China in the Late Neogene, and progressively weakened during the Quaternary, albeit with amplified fluctuations. Although the palaeoclimatic conditions reconstructed from the drill holes in eastern China are generally comparable with those records from the loess-palaeosol sequences, red clay, and deep-sea sediments in East Asia, they changed asynchronously in north-central and southeast China during the Neogene. The Late Neogene palaeoclimate was overall warmer in southeast China than on the North China Plain except for some extreme cooling periods in the Late Pleistocene. In contrast, the North China Plain experienced moderate to weak chemical weathering with the intensification of East Asian winter monsoon activities during the Late Quaternary. Regional differentiation of palaeoclimatic variability since the Pliocene in eastern China is comparable with today's climate regimes in the Changjiang and Huanghe drainage basins but with different intensities, suggesting different impacts of the East Asian palaeomonsoon during the Late Cenozoic.     

Characteristics of Ralstonia solanacearum Biovar N2 Strains in Asia

Ralstonia solanacearum biovar N2 strains isolated in Asia were compared by biochemical tests with biovar N2 strains from South America and biovar 2 (race 3) strains from Africa, America, Asia and Europe. Distinct differences were found between Asian and South American strains of biovar N2, and between Asian biovar N2 and biovar 2 strains with respect to their ability to utilize several carbon sources. Using cluster analysis based on repetitive sequence‐based polymerase chain reaction (rep‐PCR) genomic fingerprints, the Asian biovar N2 strains were divided into two groups, group 1 containing Japanese strains and group 2 containing Indonesian and Philippine strains. The fingerprints showed the genetic diversity of biovar N2 strains in Asia.     

Developmental inhibition of Drosophila suzukii by ionizing radiation

Spotted wing drosophila (SWD) has emerged as a major invasive insect pest of small berry fruits in the Americas and Europe since the late 2000s. Thus, phytosanitary treatment of commodities for export is imperative to prevent the movement of viable SWD to newer areas. In the present study, all developmental stages of SWD were irradiated with different doses of gamma and electron beam radiation to assess developmental inhibition to identify potential quarantine doses of the radiations. Ionizing radiation induced developmental inhibition of all stages of SWD. The effective doses for 99% inhibition (ED₉₉) of hatching, pupariation, and adult emergence from irradiated eggs for gamma radiation were 882, 395 and 39 Gy, respectively, compared with 2849, 687, and 41 Gy, respectively, for electron beam radiation. The ED₉₉ for inhibition of pupariation and adult emergence in irradiated larvae were 703 and 47 Gy, respectively, for gamma radiation, and 619 and 33 Gy, respectively, for electron beam radiation. Pupal irradiation did not completely inhibit adult emergence, even at 300 Gy. However, irradiation with ≥100 Gy of puparia induced adult sterility, with no egg production at all. The ED₉₉ for inhibition of F₁ egg hatchability from adults irradiated with gamma radiation and electron beam radiation was estimated to be 424 and 125 Gy, respectively. The results of the present study suggest that gamma radiation and electron beam radiation are alternatives for phytosanitary treatment. Irradiation with 100 Gy could be suggested as a potential dose for egg, larval, and pupal quarantine treatment of SWD.     

Development of nuclear microsatellite markers for the Japanese conifers Tsuga diversifolia and T. sieboldii (Pinaceae)

Nuclear microsatellite markers were developed for the two Tsuga species native to the Japanese Archipelago, Tsuga diversifolia and T. sieboldii, and a population with genetic affinities to T. diversifolia on Ulleung Island, Korea. Tsuga diversifolia and T. sieboldii are widespread dominant trees of temperate and subalpine forests in Japan but to date no genetic markers have been developed for these species. Fifteen polymorphic loci were developed and characterized, of which 14 are reliably amplified in each taxon. Across both species and the Ulleung Island population, the number of alleles per locus ranged from 3 to 26 (average = 13.93) and observed heterozygosity ranged from 0.005 to 0.935 (average = 0.535). In addition, all 15 loci were successfully amplified in a single accession of the Chinese species, T. chinensis. These markers will be useful for investigating the species’ biogeography, range‐wide genetic diversity, conservation genetic issues and potential for hybridisation.