密封介质4010NA的气相色谱分析

在４０１０ＮＡ的生产中，各组分含量严重影响其密封性能．本文讲述了利用气相色谱法对４０１０ＮＡ进行各组分定性、定量分析，同时对汽化温度、进样量等进行了考察。该法快速、简便，并具有很好的精密度和较高的准确度。

Comparative genome analysis on intraspecific evolution and nitrogen fixation of Leptospirillum ferriphilum isolates

To reveal the intraspecific evolution of Leptospirillum ferriphilum isolates which thrived in industrial bioleaching ecosystems and acid mine drainages,genome sequences of L.ferriphilum YSK,L.ferriphilum DX and L.ferriphilum ZJ were determined to compare with complete genome of L.ferriphilum ML-04.The genome comparisons reveal that extensive intraspecific variation occurs in their genomes,and that the loss and insertion of novel gene blocks of probable phage origin may mostly contribute to heterogeneity of gene content among L.ferriphilum genomes.Surprisingly,a nif gene cluster is identified in L.ferriphilum YSK and L.ferriphilum ZJ genomes.Intensive analysis and further experiments indicate that the nif gene cluster in L.ferriphilum YSK inherits from ancestor rather than lateral gene transfer.Overall,results suggest that the population of L.ferriphilum undergoes frequent genetic recombination,resulting in many closely related genome types in recent evolution.The combinatorial processes profoundly shape their physiologies and provide the basis for adaptation to different niches.

Role of ABCC2 common variants in intrahepatic cholestasis of pregnancy

The pathogenesis of intrahepatic cholestasis of pregnancy (ICP), a disorder that adversely affects maternal wellbeing and fetal outcome, is unclear. However, multiple factors probably interact along with a genetic predisposition. We would like to add some comments on a paper recently published concerning the role of ABCB11 and ABCC2 polymorphisms in both ICP and contraceptive-induced cholestasis, especially in the light of our recently published findings about a positive association between ICP and ABCC2 common variants.

On the intraspecific variability in basal metabolism and the food habits hypothesis in birds

The food habits hypothesis （FHH） stands as one of the most striking and often-cited interspecific patterns to emerge from comparative studies of endothermic energetics. The FHH identifies three components of diet that potentially produce variability in mass-independent BMR, i.e. food quality, food availability, and food predictability or environmental productivity. The hypothesis predicts that species with diets of low energy content and/or low digestibility should evolve low mass-independent BMRs. The effects of food habits on BMR have been widely investigated at the interspecific level, but the variation between individuals and populations has been largely ignored. Our focus is to compare predictions derived from interspecific studies with data collected from within-species studies to explore the mechanisms and functional significance of adaptive responses predicted by the food-habits hypothesis among birds. We conclude that if BMR is correlated with daily energy expenditure, then organisms that can lower BMR will reduce daily energy expenditure and hence, food requirements. Birds that lower BMR in stressful environments may increase survival. Nevertheless, the mechanism （s） by which birds eating a low quality diet reduce BMR and whether lower BMR affects fitness remain to be determined [Current Zoology 56 （6）： 759-766, 2010].

The intraspecific difference of the triose phosphate isomerase (tim) gene from Giardia lamblia

OBJECTIVE: To investigate the intraspecific difference of the triose phosphate isomerase (tim) gene from Giardia lamblia (G. lamblia). METHODS: Total genomic DNA of G. lamblia was extracted and partial fragments of the triose phosphate isomerase (tim) gene were amplified by polymerase chain reaction (PCR). All nucleotide sequences were analyzed by using a phylogenetic analysis, which was constructed with parsimony and Neighbor-joining (N-J) methods. RESULTS: A total of 124 variable sites (23% of all sequences detected) was defined, most of which were found at the silent sites of codons. Two similar phylogenetic trees were constructed, subdividing 16 Giardia isolates into two groups. CONCLUSION: The genetic diversity of G. lamblia appeared to be little affected by factors of both host and geography, while natural-selection played an important role in DNA molecular evolution level of the tim gene. The tim gene may be considered a very useful genetic marker of the population genetic structure of G. lamblia.

Methoxyl methyl ether isoamylene quercetin, a quercetin derivative, protects rat aorta endothelial cells against oxidation and apoptosis

Methoxyl methyl ether isoamylene quercetin （MIAQ） is one of the newly synthesized quercetin derivatives. The present study investigated the effect of MIAQ on rat aorta endothelial cells （RAECs） injured by hydrogen peroxide （H2O2）, as well as the potential mechanisms. We observed that MIAQ at 2.5-10μmol/L significantly enhanced the viability of injured RAECs, and the effect was more potent than quercetin and ct-tocopherol. However, M1AQ at the same concentration failed to show anti-oxidant activity in a cell-free system. In H2O2-injured endothelial cells treated with MIAQ （5-10μmol/L）, the level of nitric oxide （NO） and malondialdehyde was decreased, and the activities of superoxide dismutase and glutathione peroxidase was enhanced. In addition, RAECs treated with MIAQ （2.5-10 μmol/L） exhibited significant inhibiting apoptosis. In conclusion, MIAQ had protective effect on RAECs, possibly through increasing NO production and antioxidases activities, as well as inhibiting apoptosis. These findings suggest that MIAQ is possibly beneficial in the prevention of atherosclerosis and other diseases related to endothelial injury.

Efficient synthesis of thiohydantoin derivatives from amino acid esters and isothiocyanates in alkaline Al_2O_3

Various amino acid esters were reacted with different isothiocyanates in alkaline Al2O3 at room temperature for 1 h affording thiohydantoins in moderate to excellent yields.

Chromosome-scale genomes provide new insights into subspecies divergence and evolutionary characteristics of the giant panda

Extant giant pandas are divided into Sichuan and Qinling subspecies.The giant panda has many speciesspecific characteristics,including comparatively small organs for body size,small genitalia of male individuals,and low reproduction.Here,we report the most contiguous,high-quality chromosomelevel genomes of two extant giant panda subspecies to date,with the first genome assembly of the Qinling subspecies.Compared with the previously assembled giant panda genomes based on short reads,our two assembled genomes increased contiguity over 200-fold at the contig level.Additional sequencing of 25 individuals dated the divergence of the Sichuan and Qinling subspecies into two distinct clusters from 10,000 to 12,000 years ago.Comparative genomic analyses identified the loss of regulatory elements in the dachshund family transcription factor 2(DACH2)gene and specific changes in the synaptotagmin 6(SYT6)gene,which may be responsible for the reduced fertility of the giant panda.Positive selection analysis between the two subspecies indicated that the reproduction-associated IQ motif containing D(IQCD)gene may at least partly explain the different reproduction rates of the two subspecies.Furthermore,several genes in the Hippo pathway exhibited signs of rapid evolution with giant panda-specific variants and divergent regulatory elements,which may contribute to the reduced inner organ sizes of the giant panda.

Transcriptome analysis of blood stasis syndrome in subjects with hypertension

OBJECTIVE:To screen for m RNAs associated with blood stasis syndrome and to explore the genetic mechanisms of blood stasis syndrome in hypertension.METHODS:This study involved groups of patients with hypertension and blood stasis,including those with Qi deficiency,Qi stagnation,cold retention and heat retention;as well as hypertensive patients without blood stasis and healthy individuals.Human umbilical vein endothelial cells were co-cultured with the sera of these healthy individuals and patients with blood stasis syndrome.Total RNA was extracted from these cells and assessed by a high-throughput sequencing method(Solexa)and digital gene expression.Differentially expressed genes among these six groups were compared using whole genome sequences,and m RNAs associated with blood stasis syndrome identified.Differences in gene use and gene ontology function were an-alyzed.Genes enriched significantly and their pathways were determined,as were network interactions,and encoded proteins.Gene identities were confirmed by real-time polymerase chain reactions.RESULTS:Compared with cells cultured in sera of the blood stasis groups,those culture in sera of healthy individuals and of the non-blood stasis group showed 11 and 301 differences,respectively in stasis-related genes.Genes identified as differing between the blood stasis and healthy groups included activating transcription factor 4,activating transcription factor 3,DNA-damage inducible transcription factor 3,Tribbles homolog 3,CCAAT/enhancer binding protein-β,and Jun proto-oncogene(JUN).Pathway and protein interaction network analyses showed that these genes were associated with endoplasmic reticulum stress.Cells cultured in sera of patients with blood stasis and Qi deficiency,Qi stagnation,heat retention,and cold retention were compared with cells cultured in sera of patients with the other types blood stasis syndrome.The comparison showed differences in expression of 28,28,34,and 32 specific genes,respectively.CONCLUSION:The pathogenesis of blood stasis syndrome in hypertension is related to endoplasmic reticulum stress and involves the differential expression of the activating transcription factor 4,activating transcription factor 3,DNA-damage inducible transcription factor 3,Tribbles homolog 3,CCAAT/enhancer binding protein-β,and JUN genes.