[Effects of defoliation on the allocation of non-structural carbohydrates in roots of Fraxinus mandshurica seedlings.] / åŽ»å¶å¯¹æ°´æ›²æŸ³è‹—æœ¨æ ¹ç³»éžç»“æž„æ€§ç¢³æ°´åŒ–åˆç‰©åˆ†é çš„å½±å“.

Global climate changes would lead to outbreaks of leaf-feeding insects. Leaf loss could reduce photosynthate production, with consequences on non-structural carbohydrates (NSC) storage and allocation in trees. In this study, the responses of NSC and its compartment concentrations in tap-, coarse- and the first to fifth order fine roots of 2-year-old seedlings of Fraxinus mandshurica to defoliation (40% loss of leaf area) were measured from June to October. The results showed that NSC and its compartment concentrations in roots exhibited distinct seasonal dynamics in both control and defoliation treatments. Following defoliation, NSC concentration decreased in tap- and coarse roots by 3.8% and 30.7%, respectively, while increased in the first five order roots by 1.2%-23.5%, to which starch contributed majorly for each root compartment. Soluble sugar concentration was enhanced by defoliation in tap- and coarse roots by 7.1% and 62.3%, respectively, but decreased in the first to fifth order roots by 2.7%-42.8%. Defoliation had different influences on starch and soluble sugar, with positive effects on the ratio of soluble sugar to starch concentrations in tap- and coarse roots but negative effects on the first to fifth order roots. Overall, defoliation decreased photosynthate production in leaves, leading to the remobilization of starch in tap- and coarse roots and the transportation as soluble sugar to fine roots, as well as the following storage in these roots, which would facilitate the resistance of fine roots to the low temperature in winter.

Discrimination of A1555G and C1494T point mutations in the mitochondrial 12S rRNA gene by on/off switch.

The objective of this study was to apply the "on/off" switch consisting of 3' phosphorothioate-modified allele specific primers and exo(+) polymerase in single base discrimination of A1555G and C1494T mutations in the highly conserved sites of the mitochondrial 12S rRNA. The two point mutations are the hotspot mutations associated with either aminoglycoside antibiotics induced deafness or inherited nonsyndromic hearing loss. The PCR products of mitochondrial DNA (mtDNA) 12S rRNA gene were inserted into the pMD19-T vector for transformation into Escherichia coli JM109 competent cells for preparing wild-type pMD19-T/mt vector. Inverse PCR was carried out for mtDNA 12S rRNA gene C1494T and A1555G mutagenesis and DpnI endonuclease degradating methylated pMD19-T/mt vector existing in the inverse PCR products was carried out to construct the mutation-type pMD19-T/mtM vector. These constructed vectors were confirmed by DNA sequencing. Allelic specific primers targeting wild-type and mutation-type templates were designed with 3' terminal phosphorothioate modification. Two-directional primer extension was performed using Pfu polymerases. Amplified by exo(+) polymerase, allelic specific primers perfectly matching wild-type allele were extended while no products were produced from primers targeting point-mutated deafness-related allele. Similarly, allelic specific primers perfectly matching point-mutated deafness-related mutation-type allele were extended and no products were yielded from primers targeting wild-type allele. No specific product was observed in the primer extension reaction mediated by on/off switch in screening the mtDNA 12S rRNA gene harboring either C1494T or A1555G mutation in 40 healthy volunteers tested. These data suggest that the "off switch" mediated by exo(+) polymerase is highly reliable in the diagnosis of monogenic diseases and the novel "on/off" switch has enormous applications in systematic and extended screening of the12S rRNA gene A1555G and C1494T mutations. The established assay can be widely used not only for hearing loss patients but also for normal subjects before the use of aminoglycoside antibiotics.

[Correlation and location of EST markers with cold tolerance trait of common carp (Cyprinus carpio L)].

Expressed sequence tags (ESTs) are parts of complementary DNAs (cDNAs) with certain gene function.It provides us more information than other neutral markers. The association of EST markers with phenotypes can increase our understanding of the biochemical pathways and mechanisms affecting economically important traits. In this study, 12 candidate EST markers isolated from the cold-induced brain cDNA of common carp (Cyprinus carpio L.) were conducted the correlation analysis of marker and cold tolerance trait of common carp using GLM model of SPSS 17.0 software firstly, then tried to locate them in the genetic linkage map using OneMap software. As a result, eight out of 12 candidate EST makers were separately located in six linkage groups, in which marker CC009(P<0.05) and CC115 (P<0.01) were associated with cold tolerance and mapped to LG38 and LG2, respectively. Homology identity alignments showed that marker CC009 was highly homologous to the known Uridine-cytidine kinase I of Danio rerio with an identity of 94%, and marker CC115 was lowly homologous to the putative glycosyl transferase of Prochlorococcus marinus with an identity of 56%.

[Screening of microsatellite markers associated with cold tolerance of large yellow croaker (Pseudosciaena crocea R.)].

Cold tolerance is one of the major economic characters in fish. In order to discuss the cold tolerance of large yellow croaker (Pseudosciaena crocea R.), fifteen fluorescent dye-labeled microsatellite markers were applied to detect genetic differences between F1 offsprings of cold tolerance group and normal group of large yellow croaker by SSR-PCR. Each group contained 20 randomly and separately sampled individuals. As a result, marker LYC0002 five alleles (LYC0002(104 bp), LYC0002(106 bp), LYC0002(108 bp), LYC0002(110 bp), and LYC0002(112 bp)) were amplified with marker LYC0002 in both groups and 60% (12/20) of individuals had allele LYC0002(112 bp) in cold tolerance group exclusively, which indicated that this allele is probably sensitive to temperature and associated with gene for cold tolerance. In addition, four alleles (LYC0002(106 bp), LYC0002(108 bp), LYC0002(110 bp), and LYC0002(112 bp)) were sequenced individually. Sequence alignments showed that LYC0002(112 bp) allele contains 10 (CA) repeats, the remaining three alleles lacked one (CA) one by one, corresponding to the stepwise mutation model (SMM) of microsatellite.