A Novel Gelatinase from Marine Flocculibacter collagenilyticus SM1988: Characterization and Potential Application in Collagen Oligopeptide-Rich Hydrolysate Preparation.

Although the S8 family in the MEROPS database contains many peptidases, only a few S8 peptidases have been applied in the preparation of bioactive oligopeptides. Bovine bone collagen is a good source for preparing collagen oligopeptides, but has been so far rarely applied in collagen peptide preparation. Here, we characterized a novel S8 gelatinase, Aa2_1884, from marine bacterium Flocculibacter collagenilyticus SM1988T, and evaluated its potential application in the preparation of collagen oligopeptides from bovine bone collagen. Aa2_1884 is a multimodular S8 peptidase with a distinct domain architecture from other reported peptidases. The recombinant Aa2_1884 over-expressed in Escherichia coli showed high activity toward gelatin and denatured collagens, but no activity toward natural collagens, indicating that Aa2_1884 is a gelatinase. To evaluate the potential of Aa2_1884 in the preparation of collagen oligopeptides from bovine bone collagen, three enzymatic hydrolysis parameters, hydrolysis temperature, hydrolysis time and enzyme-substrate ratio (E/S), were optimized by single factor experiments, and the optimal hydrolysis conditions were determined to be reaction at 60 ℃ for 3 h with an E/S of 400 U/g. Under these conditions, the hydrolysis efficiency of bovine bone collagen by Aa2_1884 reached 95.3%. The resultant hydrolysate contained 97.8% peptides, in which peptides with a molecular weight lower than 1000 Da and 500 Da accounted for 55.1% and 39.5%, respectively, indicating that the hydrolysate was rich in oligopeptides. These results indicate that Aa2_1884 likely has a promising potential application in the preparation of collagen oligopeptide-rich hydrolysate from bovine bone collagen, which may provide a feasible way for the high-value utilization of bovine bone collagen.

Phylogeography and Population Genetics Analyses Reveal Evolutionary History of the Desert Resource Plant Lycium ruthenicum (Solanaceae).

Climactic oscillations during the Quaternary played a significant role in the formation of genetic diversity and historical demography of numerous plant species in northwestern China. In this study, we used 11 simple sequence repeats derived from expressed sequence tag (EST-SSR), two chloroplast DNA (cpDNA) fragments, and ecological niche modeling (ENM) to investigate the population structure and the phylogeographic history of Lycium ruthenicum, a plant species adapted to the climate in northwestern China. We identified 20 chloroplast haplotypes of which two were dominant and widely distributed in almost all populations. The species has high haplotype diversity and low nucleotide diversity based on the cpDNA data. The EST-SSR results showed a high percentage of total genetic variation within populations. Both the cpDNA and EST-SSR results indicated no significant differentiation among populations. By combining the evidence from ENM and demographic analysis, we confirmed that both the last interglacial (LIG) and late-glacial maximum (LGM) climatic fluctuations, aridification might have substantially narrowed the distribution range of this desert species, the southern parts of the Junggar Basin, the Tarim Basin, and the eastern Pamir Plateau were the potential glacial refugia for L. ruthenicum during the late middle Pleistocene to late Pleistocene Period. During the early Holocene, the warm, and humid climate promoted its demographic expansion in northwestern China. This work may provide new insights into the mechanism of formation of plant diversity in this arid region.

[Genetic diversity and genetic structure of Sorex isodon in Northeast China]. / ä¸­å›½ä¸œåŒ—åœ°åŒºè¿œä¸œé¼©é¼±é—ä¼ å¤šæ ·æ€§ä¸Žé—ä¼ ç»“æž„.

A total of 64 haplotypes were obtained from the complete Cytochrome b gene (Cyt b) of 77 Sorex isodon collected from three populations (Daxing'anling, Xiaoxing'anling, and Changbai Mountains) in Northeast China. The haplotype diversity was 0.9920 and the nucleotide diversity was 0.0105, indicating high genetic diversity. The genetic diversity of Changbai Mountains population was significantly higher than that of Daxing'anling and Xiaoxing'anling populations. The F-statistics, the number of migrants per generation and the genetic distance results showed that the genetic distances among the populations and among the sampling sites were generally consistent with geographical distance. Analysis of molecular variance showed that the differentiation among populations, among sampling sites, and within sampling site accounted for 33.4%, 10.2% and 56.4% of total variation, respectively. The analysis of population history showed that S. isodon in Northeast China experienced no population expansion. The reported complete sequence of Cyt b gene of S. isodon (GenBank) of Europe and other parts of Asia was downloaded to examine the genetic structure of S. isodon. The phylogenetic tree was divided into two large branches. One branch consisted mainly of Daxing'anling and Xiaoxing'anling samples. The other branch was departed into two sub-branches. Median-joining network analysis showed that there were three lineages: one lineage mainly consisted of haplotypes from Daxing'anling and Xiaoxing'anling, and also four haplotypes of Changbai Mountains, while the other lineage included a few haplotypes of three populations in Northeast China, and those from Baikal Lake, Russia and Finland. The last lineage was entirely composed of haplotypes from Changbai Mountains. The results of genetic diversity, phylogenetic tree and median-joining network all suggested that the Changbai Mountains was the refuge for S. isodon during last glacial.

[Research progress on molecular ecology of Sciurus vulgaris].

Today, the main threats for Sciurus vulgaris are illegal hunting, deforestation, and subsequent population fragmentation, combined with interspecific competition from S. carolinensis in some regions of Europe, which has led to a sharp reduction in the number of population. S. vulgaris has been listed as Near Threatened IUCN Red List and included in key protected wild animals in Jilin Province, China. The molecular ecology of S. vulgaris is developing rapidly with the rapid development of molecular biology methods. In particular, the research of mtDNA fragments and the application squirrel study microsatellite loci has further promoted the molecular ecology of S. vulgaris. In this study, the molecular phylogeny, the genetic diversity and the molecular phylogeography involving the molecular ecology of S. vulgaris were reviewed. Four areas for the future development in molecular ecology of S. vulgaris were proposed: 1) to further explore the molecular phylogeny relationship between S. vulgaris and S. lis; 2) the comparative analysis of the genetic diversity of S. vulgaris for continuous populations, isolated populations and metapopulation; 3) the analysis of molecular phylogeography of S. vulgaris based on other markers of nuclear; 4) to explore whether there existed the quaternary glacial refuge in Asia.

Effects and underlying mechanisms of human opiorphin on cardiovascular activity in anesthetized rats.

The present study was performed to investigate the peripheral cardiovascular effects of opiorphin in anesthetized rats. Intravenous (i.v.) injection of opiorphin (50-500nmol/kg) caused marked dose-dependent increase in blood pressure and heart rate. The pressor and tachycardic responses induced by opiorphin (300nmol/kg, i.v.) were significantly decreased by pretreatment with angiotensin-converting enzyme inhibitor captopril or angiotensin II type 1 (AT1) receptor antagonist valsartan, which suggested that endogenous angiotensin may be involved in the response to opiorphin. Pretreatment with α-adrenoreceptor antagonist phentolamine and ß-adrenoceptor antagonist propranolol respectively attenuated the pressor response induced by opiorphin. Propranolol, but not phentolamine, inhibited the tachycardic response. Moreover, reserpine blocked both responses to opiorphin. These findings indicated that the effects of opiorphin to increase blood pressure and heart rate might be due to the stimulation of sympathetic ganglia. Additionally, studies with bilaterally adrenalectomized rats showed that adrenal medulla may be involved in the cardiovascular regulation of opiorphin. In addition, pretreatment with nonselective opioid receptor antagonist naloxone did not modify the cardiovascular responses to opiorphin, suggesting that the effects of opiorphin were not related to the opioid system. Furthermore, radioimmunoassay (RIA) showed that opiorphin significantly increased endogenous levels of angiotensin II and angiotensin III. In summary, all the results indicate that the cardiovascular effects induced by opiorphin are mediated through the renin-angiotensin system (RAS), the sympathetic ganglia and adrenal medulla, but not the opioid system.

Phylogeography of Pinus tabulaeformis Carr. (Pinaceae), a dominant species of coniferous forest in northern China.

How coniferous trees in northern China changed their distribution ranges in response to Quaternary climatic oscillations remains largely unknown. Here we report a study of the phylogeography of Pinus tabulaeformis, an endemic and dominant species of coniferous forest in northern China. We examined sequence variation of maternally inherited, seed-dispersed mitochondrial DNA (mtDNA) (nad5 intron 1 and nad4/3-4) and paternally inherited, pollen- and seed-dispersed chloroplast DNA (cpDNA) (rpl16 and trnS-trnG) within and among 30 natural populations across the entire range of the species. Six mitotypes and five chlorotypes were recovered among 291 trees surveyed. Population divergence was high for mtDNA variation (G(ST) = 0.738, N(ST) = 0.771) indicating low levels of seed-based gene flow and significant phylogeographical structure (N(ST) > G(ST), P < 0.05). The spatial distribution of mitotypes suggests that five distinct population groups exist in the species: one in the west comprising seven populations, a second with a north-central distribution comprising 15 populations, a third with a southern and easterly distribution comprising five populations, a fourth comprising one central and one western population, and a fifth comprising a single population located in the north-central part of the species' range. Each group apart from the fourth group is characterized by a distinct mitotype, with other mitotypes, if present, occurring at low frequency. It is suggested, therefore, that most members of each group apart from Group 4 are derived from ancestors that occupied different isolated refugia in a previous period of range fragmentation of the species, possibly at the time of the Last Glacial Maximum. Possible locations for these refugia are suggested. A comparison of mitotype diversity between northern and southern subgroups within the north-central group of populations (Group 2) showed much greater uniformity in the northern part of the range both within and between populations. This could indicate a northward migration of the species from a southern refugium in this region during the postglacial period, although alternative explanations cannot be ruled out. Two chlorotypes were distributed across the geographical range of the species, resulting in lower levels of among-population chlorotype variation. The geographical pattern of variation for all five chlorotypes provided some indication of the species surviving past glaciations in more than one refugium, although differentiation was much less marked, presumably due to the greater dispersal of cpDNA via pollen.