The causality between gut microbiome and liver cirrhosis: a bi-directional two-sample Mendelian randomization analysis.

Background and aim: Previous studies have reported an association between gut microbiota and cirrhosis. However, the causality between intestinal flora and liver cirrhosis still remains unclear. In this study, bi-directional Mendelian randomization (MR) analysis was used to ascertain the potential causal effect between gut microbes and cirrhosis. Methods: Large-scale Genome Wide Association Study (GWAS) data of cirrhosis and gut microbes were obtained from FinnGen, Mibiogen consortium, and a GWAS meta-analysis of Alcoholic cirrhosis (ALC). Two-sample MR was performed to determine the causal relationship between gut microbiota and cirrhosis. Furthermore, a bi-directional MR analysis was employed to examine the direction of the causal relations. Result: In MR analysis, we found that 21 gut microbiotas were potentially associated with cirrhosis. In reverse MR analysis, 11 gut microbiotas displayed potentially associations between genetic liability in the gut microbiome and cirrhosis. We found that the family Lachnospiraceae (OR: 1.59, 95% CI:1.10-2.29) might be harmful in cirrhotic conditions (ICD-10: K74). Furthermore, the genus Erysipelatoclostridium might be a protective factor for cirrhosis (OR:0.55, 95% CI:0.34-0.88) and PBC (OR:0.68, 95% CI:0.52-0.89). Combining the results from the MR analysis and reverse MR analysis, we firstly identified the Genus Butyricicoccus had a bi-directional causal effect on PBC (Forward: OR: 0.37, 95% CI:0.15-0.93; Reverse: OR: 1.03, 95% CI:1.00-1.05). Conclusion: We found a new potential causal effect between cirrhosis and intestinal flora and provided new insights into the role of gut microbiota in the pathological progression of liver cirrhosis.

[Effects of Water-salt Environment on Freshwater Wetland Soil C, N, and P Ecological Stoichiometric Characteristics in the Yellow River Estuary Wetland].

Carbon (C), nitrogen (N), and phosphorus (P) are important nutrients, and their ecological stoichiometric characteristics can reflect the quality and fertility capacity of soil, which is critical to understanding the stable mechanisms of estuarine wetland ecosystems. Under global changes, the increase in salinity and flooding caused by sea level rise will lead to changes in biogeochemical processes in estuarine wetlands, which is expected to affect the ecological stoichiometric characteristics of soil C, N, and P and ultimately interfere with the stability of wetland ecosystems. However, it remains unclear how the C, N, and P ecological stoichiometric characteristics respond to the water-salt environment in estuarine wetlands. We differentiated changes in the C, N, and P ecological stoichiometric characteristics through an ex-situ culture experiment for 23 months in the Yellow River Estuary Wetland. The five sites with distinct tidal hydrology were selected to manipulate translocation of soil cores from the freshwater marsh to high-, middle-, and low-tidal flats in June 2019. The results showed that soil water content (SWC); electrical conductivity (EC); and C, N, and P ecological stoichiometric characteristics of freshwater marsh soil significantly changed after translocation for 23 months. SWC decreased on the high- and middle-tidal flats (P<0.05) and increased on the low-tidal flat (P<0.05). EC increased to different degrees on all three tidal flats (P<0.05). Soil total organic carbon (TOC) and total nitrogen (TN) were significantly lower on the high-tidal flat (P<0.05), whereas total phosphorus (TP) was significantly lower on the middle- and high-tidal flats (P<0.05). C:N was decreased on the high- and middle-tidal flats (P<0.05); C:P and N:P were lower on the high-tidal flat; and all C, N, and P ecological stoichiometric characteristics showed no change on the low-tidal flat (P>0.05). Pearson's analysis showed that the ecological stoichiometric characteristics of C, N, and P were related to some properties of soil over the culture sites. The PLS-SEM model showed that the water-salt environment had different effects on soil C:N, C:P, and N:P through the main pathways of negative effects on soil TOC and TP. The results suggest that sea level rise may impact the C, N, and P ecological stoichiometric characteristics in freshwater marsh soil, resulting in some possible changes in the nutrient cycles of estuarine wetlands.

The Whole-transcriptome Landscape of Diabetes-related Sarcopenia Reveals the Specific Function of Novel lncRNA Gm20743.

While the exact mechanism remains unclear, type 2 diabetes mellitus increases the risk of sarcopenia which is characterized by decreased muscle mass, strength, and function. Whole-transcriptome RNA sequencing and informatics were performed on the diabetes-induced sarcopenia model of db/db mice. To determine the specific function of lncRNA Gm20743, the detection of Mito-Sox, reactive oxygen species, Ethynyl-2'-deoxyuridine, and myosin heavy chain was performed in overexpressed and knockdown-Gm20743 C2C12 cells. RNA-seq data and informatics revealed the key lncRNA-mRNA interactions and indicated a potential regulatory role of lncRNAs. We characterized three core candidate lncRNAs Gm20743, Gm35438, 1700047G03Rik, and their potential function. Furthermore, the results suggested lncRNA Gm20743 may be involved in regulating mitochondrial function, oxidative stress, cell proliferation, and myotube differentiation in skeletal muscle cells. These findings significantly improve our understanding of lncRNAs that may mediate muscle mass, strength, and function in diabetes and represent potential therapeutic targets for diabetes-induced sarcopenia.

Artificial intelligence improves accuracy, efficiency, and reliability of a handheld infrared eccentric autorefractor for adult refractometry.

AIM: To evaluate the accuracy, efficiency, and reliability of a handheld infrared eccentric autorefractor (hICA) with artificial intelligence (AI) by comparing its refraction measurements to those recorded using hICA and a clinical table-mounted automatic refractor (TAR). METHODS: A cross-sectional study using three optometers, including hICA with or without AI and TAR, for refractometry of adults (aged 19-49 years old) with no signs of ocular disease or trauma in the absence of cycloplegia. Right and left eye refraction data were recorded, including the spherical equivalent (SE), diopter of spherical power (DS), diopter of cylindrical power (DC) decomposed into vectors J0 and J45, and measurement times. To avoid analytical difficulties associated with the interdependence of observations between eyes from the same individual, the Generalized Estimation Equation was used to compare the SE, DS, J0 and J45 measurements, and the times thereof, among the different groups. The intraclass correlation coefficient (ICC) and Spearman's rank correlation coefficient were used to evaluate correlations among the measurements recorded by the three different instruments. Bland-Altman were used to analyze the precision of the equipment by the agreement. RESULTS: A total of 70 patients (140 eyes; mean age: 31.37y; range: 19-49y) were assessed using refractometry. In a brightly lit environment, there was no significant difference between the mean SE recorded using TAR and that recorded using hICA with AI or without AI (both P>0.05). In an intense-light environment, hICA equipped with AI showed a better detection rate than without AI. Light intensity had a greater effect on dioptric measurements recorded using hICA without AI (P<0.001) than on those recorded using the one equipped with AI (P<0.05). Measurement times varied significantly between the different light intensities and instruments (P<0.05). CONCLUSION: For the normal human eyes, AI may improve the accuracy, efficiency, and reliability of measurements recorded using hICA in various light environments.

Porous and Ultra-Flexible Crosslinked MXene/Polyimide Composites for Multifunctional Electromagnetic Interference Shielding.

Lightweight, ultra-flexible, and robust crosslinked transition metal carbide (Ti3C2 MXene) coated polyimide (PI) (C-MXene@PI) porous composites are manufactured via a scalable dip-coating followed by chemical crosslinking approach. In addition to the hydrophobicity, anti-oxidation and extreme-temperature stability, efficient utilization of the intrinsic conductivity of MXene, the interfacial polarization between MXene and PI, and the micrometer-sized pores of the composite foams are achieved. Consequently, the composites show a satisfactory X-band electromagnetic interference (EMI) shielding effectiveness of 22.5 to 62.5 dB at a density of 28.7 to 48.7 mg cm-3, leading to an excellent surface-specific SE of 21,317 dB cm2 g-1. Moreover, the composite foams exhibit excellent electrothermal performance as flexible heaters in terms of a prominent, rapid reproducible, and stable electrothermal effect at low voltages and superior heat performance and more uniform heat distribution compared with the commercial heaters composed of alloy plates. Furthermore, the composite foams are well attached on a human body to check their electromechanical sensing performance, demonstrating the sensitive and reliable detection of human motions as wearable sensors. The excellent EMI shielding performance and multifunctionalities, along with the facile and easy-to-scalable manufacturing techniques, imply promising perspectives of the porous C-MXene@PI composites in next-generation flexible electronics, aerospace, and smart devices.

MICU3 regulates mitochondrial Ca2+-dependent antioxidant response in skeletal muscle aging.

Age-related loss of skeletal muscle mass and function, termed sarcopenia, could impair the quality of life in the elderly. The mechanisms involved in skeletal muscle aging are intricate and largely unknown. However, more and more evidence demonstrated that mitochondrial dysfunction and apoptosis also play an important role in skeletal muscle aging. Recent studies have shown that mitochondrial calcium uniporter (MCU)-mediated mitochondrial calcium affects skeletal muscle mass and function by affecting mitochondrial function. During aging, we observed downregulated expression of mitochondrial calcium uptake family member3 (MICU3) in skeletal muscle, a regulator of MCU, which resulted in a significant reduction in mitochondrial calcium uptake. However, the role of MICU3 in skeletal muscle aging remains poorly understood. Therefore, we investigated the effect of MICU3 on the skeletal muscle of aged mice and senescent C2C12 cells induced by D-gal. Downregulation of MICU3 was associated with decreased myogenesis but increased oxidative stress and apoptosis. Reconstitution of MICU3 enhanced antioxidants, prevented the accumulation of mitochondrial ROS, decreased apoptosis, and increased myogenesis. These findings indicate that MICU3 might promote mitochondrial Ca2+ homeostasis and function, attenuate oxidative stress and apoptosis, and restore skeletal muscle mass and function. Therefore, MICU3 may be a potential therapeutic target in skeletal muscle aging.

Comparison of delta-shaped anastomosis and Billroth I reconstruction after laparoscopic distal gastrectomy for gastric cancer.

BACKGROUND: This study intends to compare the short-term effects and long-term survival of gastric cancer patients who underwent delta-shaped anastomosis (DA) and Billroth I reconstructions after laparoscopic distal gastrectomy. METHODS: We retrospectively collected data from 257 patients with gastric cancer who underwent laparoscopic distal gastrectomy between January 2013 and December 2017. Patients were classified into 2 groups according to the reconstruction method used: the DA group (n=91) and the Billroth I group (n=166). The clinical data, short-term efficacy, and long-term results were compared between the 2 groups. RESULTS: The operation time (P<0.001) and the post-operative length of hospital stay (P<0.001) were shorter in the DA group than in the Billroth I group. The time to the first oral intake of a soft diet after surgery was earlier in the DA group than in the Billroth I group (P=0.014). Kaplan-Meier (log-rank test) analysis showed no significant difference in the 5-year survival rates between the 2 groups for patients at the same pathological stage. Multivariate analysis showed that abnormal carcinoembryonic antigen (CEA) (P=0.006), chemotherapy (P<0.001), T stage (P<0.001), and N stage (P<0.001) were independent prognostic factors for survival. CONCLUSIONS: DA and Billroth I are feasible and safe reconstruction methods of the digestive tract after gastric cancer. DA is the recommended reconstruction method for laparoscopic distal gastrectomy.

FGF19 protects skeletal muscle against obesity-induced muscle atrophy, metabolic derangement and abnormal irisin levels via the AMPK/SIRT-1/PGC-α pathway.

Obesity is associated with biological dysfunction in skeletal muscle. As a condition of obesity accompanied by muscle mass loss and physical dysfunction, sarcopenic obesity (SO) has become a novel public health problem. Human fibroblast growth factor 19 (FGF19) plays a therapeutic role in metabolic diseases. However, the protective effects of FGF19 on skeletal muscle in obesity and SO are still not completely understood. Our results showed that FGF19 administration improved muscle loss and grip strength in young and aged mice fed a high-fat diet (HFD). Increases in muscle atrophy markers (FOXO-3, Atrogin-1, MuRF-1) were abrogated by FGF19 in palmitic acid (PA)-treated C2C12 myotubes and in the skeletal muscle of HFD-fed mice. FGF19 not only reduced HFD-induced body weight gain, excessive lipid accumulation and hyperlipidaemia but also promoted energy expenditure (PGC-1α, UCP-1, PPAR-γ) in brown adipose tissue (BAT). FGF19 treatment restored PA- and HFD-induced hyperglycaemia, impaired glucose tolerance and insulin resistance (IRS-1, GLUT-4) and mitigated the PA- and HFD-induced decrease in FNDC-5/irisin expression. However, these beneficial effects of FGF19 on skeletal muscle were abolished by inhibiting AMPK, SIRT-1 and PGC-1α expression. Taken together, this study suggests that FGF19 protects skeletal muscle against obesity-induced muscle atrophy, metabolic derangement and abnormal irisin secretion partially through the AMPK/SIRT-1/PGC-α signalling pathway, which might be a potential therapeutic target for obesity and SO.

Type 2 diabetes-induced overactivation of P300 contributes to skeletal muscle atrophy by inhibiting autophagic flux.

AIMS: Although autophagy impairment is a well-established cause of muscle atrophy and P300 has recently been identified as an important regulator of autophagy, the effects of P300 on autophagy and muscle atrophy in type 2 diabetes (T2D) remain unexplored. We aimed at characterizing the role of P300 in diabetic muscle and its underlying mechanism. MAIN METHODS: Protein levels of phosphorylated P300, total P300, acetylated histone H3, LC3, p62 and myosin heavy chain, and mRNA levels of Atrogin-1 and MuRF1 were analyzed in palmitic acid (PA)-treated myotubes and db/db mice. Autophagic flux was assessed using transmission electron microscopy, immunofluorescence and mRFP-GFP-LC3 lentivirus transfection in cells. Muscle weight, blood glucose and grip strength were measured in mice. Hematoxylin and eosin (H&E) staining was performed to determine changes in muscle fiber size. To investigate the effects of P300 on autophagy and myofiber remodeling, a P300 specific inhibitor, c646, was utilized. 3-Methyladenine (3-MA) was utilized to inhibit autophagosomes formation, and chloroquine (CQ) was used to block autophagic flux. KEY FINDINGS: Phosphorylation of P300 in response to PA enhanced its activity and subsequently suppressed autophagic flux, leading to atrophy-related morphological and molecular changes in myotubes. Inhibition of P300 reestablished autophagic flux and ameliorated PA-induced myotubes atrophy. However, this effect was largely abolished by co-treatment with the autophagy inhibitor CQ. In vivo results demonstrated that inhibition of P300 partially rescued muscle wasting in db/db mice, accompanied with autophagy reactivation. SIGNIFICANCE: The findings revealed that T2D-induced overactivation of P300 contributes to muscle atrophy by blocking autophagic flux.

Effect of sarcolipin-mediated cell transdifferentiation in sarcopenia-associated skeletal muscle fibrosis.

Fibrosis is a key pathological event during muscle aging that accelerates the development of sarcopenia. We show that sarcolipin (SLN) is highly expressed during aging, promotes intracellular calcium overload and participates in impaired myogenic differentiation. d-Galactose (D-gal) was used to induce senescence in C2C12 myoblasts. Conventional AAV-mediated SLN knockdown cells were used to study the role of SLN in muscle physiology and pathophysiology. C2C12 cells were treated with D-gal, which promoted fibrosis and SLN upregulation. The expression of TGF-ß1 and α-SMA, which participate in myogenic transdifferentiation, were also elevated. C2C12 cells with reduced sarcolipin expression produced decreased amounts of collagen. Our study identified an unrecognized role of SLN in regulating myogenic transdifferentiation during aging-associated skeletal muscle cell fibrosis. Targeting SLN may be a novel therapeutic strategy to relieve sarcopenia-associated muscle fibrosis.

[Vegetative reproduction characteristics of Leymus chinensis in heterogeneous habitats in Songnen Plain, China]. / æ¾å«©å¹³åŽŸå¼‚è´¨ç”Ÿå¢ƒç¾Šè‰ç§ç¾¤è¥å »ç¹æ®–ç‰¹å¾.

The perennial clonal grasses rely mainly on vegetative reproduction to achieve continuous regeneration. Buds and juvenile tillers formed by buds are potential populations for vegetative reproduction. We compared the composition and size of potential population of Leymus chinensis in the enclosure meadow, long-term mowing meadow, enclosing sand-covered meadow, and forest-grassland, with excavation sampling by unit area and using vegetative reproduction generations to classify the age of tillers, rhizomes and various types of buds and juvenile tillers. The results showed that at the end of the growing season, potential population of L. chinensis was composed of rhizome buds and buds of tiller growing upwards at different ages, as well as juvenile tillers on the tillers and rhizomes. Across the four habitats, the potential population of tillers of L. chinensis was composed of 3-4 age classes, and the rhizomes' potential population consisted of four age classes, of which the potential population formed by rhizomes accounted for 68.3% of the total potential population. The potential population produced by 1st age class tillers and rhizomes accounted for 60.2% of the total, which was the main part of the potential population composition and the main source of population renewal. The potential population of tillers was the most abundant in long-term mowing meadow. The potential population of rhizomes was the most abundant in enclosing sand-covered meadow. The vegetative fertility of tillers and rhizomes was the highest in young age. The vegetative fertility of rhizomes was 10.0 times as that of tillers, which dominated the vegetative reproduction of L. chinensis. The potential population composition of L. chinensis varied greatly across different habitats, reflecting the divergent adaptation to habitat variation.

[Module growth and biomass allocation of Chloris virgate clone at different growth stages in Songnen Plain, China]. / æ¾å«©å¹³åŽŸä¸åŒç”Ÿè‚²æœŸè™Žå°¾è‰æ— æ€§ç³»æž„ä»¶ç”Ÿé•¿ä¸Žç”Ÿç‰©é‡åˆ†é .

The growth characteristic and strategies of Chloris virgate at different growth stages were examined in Songnen Plain by analyzing the quantitative characters and biomass allocation of aboveground and belowground parts at shooting and ripening stages in C. virgate population, with a large amount of sampling. The results showed that height, total root length, total root surface area, root volume, aboveground biomass, belowground biomass, and total biomass were significantly different between the two growth stages. There was power allometric relationship between total biomass and biomass allocation of aboveground and belowground, respectively. At shooting stage, there was a significant linear isometric growth between the total biomass and the number of ramets, total root length, total root surface area and root volume, but there was a power allometric growth at ripening stage. C. virgate clone showed different growth strategies under different growth stages, with a priority expansion strategy of clonal outer space at shooting stage and a complementary and expansive strategy in the inner and outer space of the clones at ripening stage.

[Age structure and growth characteristics of Juglans cathayensis seedling populations at different slope aspects in Wild Walnut Natural Conservation Area of Xinjiang, China]. / æ–°ç–†é‡Žæ ¸æ¡ƒè‡ªç„¶ä¿æŠ¤åŒºä¸åŒå¡å‘é‡Žæ ¸æ¡ƒå¹¼è‹—ç§ç¾¤å¹´é¾„ç»“æž„åŠç”Ÿé•¿ç‰¹å¾.

For grasping the composition and growth characteristics of seedling populations of Juglans cathayensis, a national grade 2 endangered plant, four 2-hm2 plots were set up at different slope aspects in Wild Walnut Natural Conservation Area of Xinjiang, China. Adjacent lattice method was used to survey J. cathayensis seedlings. The relationships between the number, basal diameter and plant height of J. cathayensis seedling populations were analyzed. The results showed that seedlings at 1st age were more abundant on sunny, semi-sunny, shady and semi-shady slopes. The number of seedlings was predominant at 1st-3rd age. Seedling populations at different slope aspects showed an expanding age structure. 5.7% of 1st age seedlings could survive to 4th age, and 1.7% could survive to 7th age. The number of J. cathayensis seedlings had a critical turning point at the 3rd age. The seedlings of J. cathayensis were considered as r-strategists in their lives. The basal diameter and plant height of seedlings were slow-growing before 3rd age and fast-growing after 3rd age. Average growth rate of basal diameter was 3.6 mm·a-1and decreased in the order of shady slope, sunny slope, semi-shady slope and semi-sunny slope. Average growth rate of plant height was 9.0 cm·a-1 and decreased in the order of sunny slope, semi-sunny slope, semi-shady slope and shady slope. Basal diameter and plant height of seedlings exponentially increased with the increase of age. The relationships between plant height and basal diameter showed power function. Growth rates of seedling traits could be reflected by the properties and parameters of functions.

[Distribution patterns of Juglans cathayensis populations at different slope aspects in Tianshan valley in Xinjiang, China]. / æ–°ç–†å¤©å±±å³¡è°·ä¸åŒå¡å‘é‡Žæ ¸æ¡ƒç§ç¾¤åˆ†å¸ƒæ ¼å±€.

Eight 4000 m2 plots were set up at eight sites distributed on sunny and shady slopes of four valleys, and adjacent lattice method was used to survey Juglans cathayensis populations. At different scales, aggregation intensity index such as variance/mean ration and deviation index (Cx), negative binomial parameter (K), clumping index (I), mean crowding index (m*), patchiness index (PAI) and aggregation index (Ca) were used to analyze distribution patterns of populations. With the increase of surveying scales, the distribution patterns changed from cluster to random. Populations presented a clustered distribution when the scale was 25 m2. Aggregation intensity had great differences among different plots, and the maximum one located on west shady slope and the minimum one did on south shady slope. However, populations presented a random distribution when the scale was 50-400 m2. When scale was 25 m2, saplings, young and mature trees showed a clustered distribution. Aggregation intensity of mature trees was the maximum one and that of saplings was the minimum one. When the scale was 200-400 m2, saplings, young and mature trees showed random distribution. The pattern size of J. cathayensis populations was 25 m2 and pattern intensity was 2.49-9.38 m2. The pattern intensity of young trees was the largest and that of mature trees was the least in population components. In a word, when sampling scale was close to population patch size, a reliable conclusion usually could be obtained by using adaptive determination method and multi-index comprehensive decision.

[Demography and spectrum analysis of Juglans cathayensis populations at different altitudes in the west Tianshan valley in Xinjiang, China].

Juglans cathayensis is an endangered plant species and listed as a class II protected species of the national government of China. In order to grasp the current state of J. cathayensis populations and predict the population dynamics in the future, a large-sample investigation was conducted in the sample plots along different altitude gradients in four valleys in J. cathayensis conservation area. According to the diameter at breast height (DBH) class of the trees, the age class structures of the populations were analyzed, and static life tables for J. cathayensis populations in different habitats along the altitude gradient was constructed by smoothing out technique, and comparative fluctuations cycles of the populations in different habitats were carried out by spectral analysis. The results showed that DBH decreased gradually with the increasing altitude. The population was composed of 19 age classes in the low-altitude habitat (1241 - 1380 m) with the maximum DBH of 91.7 cm, 18 age classes in the middle-altitude habitat (1381 - 1490 m) with the maximum DBH of 82.8 cm, and 13 age classes in the high-altitude habitat (1491 - 1670 m) with the maximum DBH of 58.9 cm. Life expectancies of J. cathayensis populations were fluctuant for the same age class at different altitudes and for different age classes at the same altitude. In the three altitude-different habitats, the survival curves of the populations trended toward Deevey- II type and the age structures of the populations were expanding. The curves of mortality showed three peaks, and the mortality rates of 9 age classes at 1241 - 1380 m and 1491 - 1670 m above sea levels were the highest, being 55.9% and 89.8%, respectively, and the mortality rate of 12 age classes at 1381 - 1490 m above sea level was the highest (79.4%). The population dynamics was significantly affected by the fundamental wave of biological characteristic throughout the life cycle of J. cathayensis population, and small cycles of multi-harmonic superposition with large cycles were presented. J. cathayensis is a long lifespan tree and a major dominant species in this conservation area. The natural regeneration of its current populations is good. If not strong anthropogenic disturbances or severe natural disasters, J. cathayensis would maintain the dominant position in the community.

[Effects of rodents and litter coverage on the seed fate of wild Prunus divaricata in wild fruit forest of Tianshan Mountain, Northwest China].

The dynamic variation characteristics of seed bank and the main factors influencing the fate of Prunus divaricata seeds under the pressure of rodent predation and litter coverage were investigated with artificial soil seed banks from September, 2010 to April, 2013. It was found that there was about 48.3% of seeds germinated under the rodent predation disturbance conditions, 50% of the seeds was predated in situ or removed, and only about 4% decayed. The artificial seed bank formed a short-term persistent soil seed bank without any rodent predation disturbance, and the seeds could germinate even though they had been stored in the seed bank for three years. Soil burial provided a lower predation pressure and promoted the recruitment of wild P. divaricata seedlings, removal and predation in situ by animals was an important factor affecting the fate of seeds. At the same time, seeds removed and foraged in situ in the control and litter coverage samples were significantly less than that in the bare soil samples. Ground coverage reduced the removal and predation of seeds by rodents, but the effect was not enough to result in more seedlings. Rodent predation and removal were the main factors that could affect the seed fate and dynamics of seed bank.

[Spatial patterns of plant species diversity in a degraded successional series of fragmented Leymus chinensis meadow in Songnen Plain of Northeast China].

Species diversity pattern is a hot topic in the forward field of international biodiversity research. Taking a degraded successional series (six communities distributed in 144 isolated patches) of fragmented Leymus chinensis meadow in Songnen Plain as test objects, this paper studied the spatial patterns of alpha, beta, and gamma diversities and related mechanisms. Eighty seven plant species were recorded, but none of them were distributed across all patches. L. chinensis + Kalimeris integrifolia community or L. chinensis community had higher alpha, beta, and gamma diversities, with more rare species and endemic species, while Kochia sieversiana community had lower alpha, beta, and gamma diversities, with few rare species and no endemic species. The gamma diversity showed significant positive correlation with a diversity, but no correlation with beta diversity. There was a significant power function correlation between the a diversity and the area of single patch of the six communities, but no correlation between the beta diversity (Bray-Curtis similarity index, Sjk ) and the area of single patch of the communities except for L. chinensis + K. integrifolia. Both the alpha angamma diversity showed significant correlations with the mean patch area and total patch area, but the p3beta diversity did not. The higher the species richness in the communities, the more the rare species and endemic species, the larger the possibility of species depopulation in local patches was. The importance of beta diversity for shaping species diversity pattern was related to the degree of habitat fragmentation.

[Age structures of Spodiopogon sibiricus populations on weedy meadow and elm woodland in Songnen Plain, northeast China].

In 2003 and 2006, investigations were made on the age structures of Spodiopogon sibiricus populations as well as the matter productivities and vegetative reproduction capacities of different age-class modules of the populations on the weedy meadow and elm woodland in Songnen Plain of northeast China. At the two habitats, the tillers of S. sibiricus all consisted of 2-3 age classes, and the rhizomes all composed of 4 age classes. Both the tillers and the rhizomes had the greatest proportion of 1- or 2-year-old, and the age structures were of expansive or stable. The 1- or 2-year-old tiller-node buds were dominant, and the rhizome topmost buds occupied 29.4%-45.0%, being of significance to the population regeneration in the next year. The 1- or 2-year-old modules of the tillers and rhizomes had the highest matter productivity and vegetative reproduction capacity, and the rhizomes had higher vegetative reproduction capacity than the tiller-nodes.

[Reproductive tillers phenotypic plasticity of Elymus excelsus population at different earring time in Songnen Plain of Northeast China].

The reproductive tillers of Elymus excelsus population in Songnen Plain were randomly marked with labels every other four days (five times in total) at early earring stage, and the marked tillers were harvested at dough stage, with the differences of their quantitative characteristics as well as the relationships between the quantitative characteristics and the shortened time of reproductive growth were analyzed. With the shortened time of reproductive growth, the quantitative characteristics of the reproductive tillers decreased gradually, which was not beneficial to the reproductive growth, reproductive allocation, and fruiting of reproductive tillers. The later the earring time, the larger the impact on fruiting and reproductive allocation was. When the reproductive growth time was shortened by 16 days, the grain biomass, setting penentage, reproductive allocation I , and reproductive allocation II decreased by 99.4%, 98.8%, 54.3%, and 99.2%, respectively. With the shortened time of reproductive growth, the tiller height decreased linearly, spike biomass, reproductive allocation I, and setting penentage decreased exponentially, tiller biomass, spike length, and floret number decreased powerly, and grain biomass, grain number, and reproductive allocation II decreased logarithmically.