Does selective logging change ground-dwelling beetle assemblages in a subtropical broad-leafed forest of China?

Selective logging with natural regeneration is advocated as a near-to-nature strategy and has been implemented in many forested systems during the last decades. However, the efficiency of such practices for the maintenance of forest species are poorly understood. We compared the species richness, abundance and composition of ground-dwelling beetles between selectively logged and unlogged forests to evaluate the possible effects of selective logging in a subtropical broad-leafed forest in southeastern China. Using pitfall traps, beetles were sampled in two naturally regenerating stands after clearcuts (ca. 50 years old, stem-exclusion stage: selectively logged 20 years ago) and two mature stands (> 80 years old, understory re-initiation stage: selectively logged 50 years ago) during 2009 and 2010. Overall, selective logging had no significant effects on total beetle richness and abundance, but saproxylic species group and some abundant forest species significantly decreased in abundance in selectively logged plots compared with unlogged plots in mature stands. Beetle assemblages showed significant differences between selectively logged and unlogged plots in mature stands. Some environmental characteristics associated with selective logging (e.g., logging strategy, stand age, and cover of shrub and moss layers) were the most important variables explaining beetle assemblage structure. Our results conclude that selective logging has no significant impacts on overall richness and abundance of ground-dwelling beetles. However, the negative effects of selective logging on saproxylic species group and some unlogged forest specialists highlight the need for large intact forested areas for sustaining the existence of forest specialist beetles.

The Relative Importance of Spatial and Local Environmental Factors in Determining Beetle Assemblages in the Inner Mongolia Grassland.

The aim of this paper is to increase understanding of the relative importance of the input of geographic and local environmental factors on richness and composition of epigaeic steppe beetles (Coleoptera: Carabidae and Tenebrionidae) along a geographic (longitudinal/precipitation) gradient in the Inner Mongolia grassland. Specifically, we evaluate the associations of environmental variables representing climate and environmental heterogeneity with beetle assemblages. Beetles were sampled using pitfall traps at 25 sites scattered across the full geographic extent of the study biome in 2011-2012. We used variance partitioning techniques and multi-model selection based on the Akaike information criterion to assess the relative importance of the spatial and environmental variables on beetle assemblages. Species richness and abundance showed unimodal patterns along the geographic gradient. Together with space, climate variables associated with precipitation, water-energy balance and harshness of climate had strong explanatory power in richness pattern. Abundance pattern showed strongest association with variation in temperature and environmental heterogeneity. Climatic factors associated with temperature and precipitation variables and the interaction between climate with space were able to explain a substantial amount of variation in community structure. In addition, the turnover of species increased significantly as geographic distances increased. We confirmed that spatial and local environmental factors worked together to shape epigaeic beetle communities along the geographic gradient in the Inner Mongolia grassland. Moreover, the climate features, especially precipitation, water-energy balance and temperature, and the interaction between climate with space and environmental heterogeneity appeared to play important roles on controlling richness and abundance, and species compositions of epigaeic beetles.

Short-Term Responses of Ground-Dwelling Beetles to Ice Storm-Induced Treefall Gaps in a Subtropical Broad-Leaved Forest in Southeastern China.

Periodic natural disturbances shape the mosaic character of many landscapes and influence the distribution and abundance of organisms. In this study, we tested the effect of ice storm-induced treefall gaps on ground-dwelling beetle assemblages in different-aged successional stands of subtropical broad-leaved forest in southeastern China. We evaluated the relative importance of gap-phase microhabitat type (within gap, gap edge, and interior shaded) within different stand ages (regenerating stands and mature stands) as determinants of changes in beetle diversity and community structure. At 18 replicate sites sampled during 2009-2010, no significant differences were found in species richness and the abundances of the most common beetle species captured in pitfall traps among the three gap-phase microhabitat types, but the abundances of total beetles, as well as fungivorous and phytophagous species groups, were significantly lower in gap microhabitats than in interior shaded microhabitats in mature stands. Beetle assemblage composition showed no significant differences among the three microhabitat types, and only the fauna of gap plots slightly diverged from those of edge and shaded plots in mature stands. Cover of shrubs and stand age significantly affected beetle assemblage structure. Our results suggest that beetle responses to gap-phase dynamics in early successional forests are generally weak, and that effects are more discernible in the mature stands, perhaps due to the abundance responses of forest-specialist species.

Composition and distribution of ground-dwelling beetles among oak fragments and surrounding pine plantations in a temperate forest of North China.

In this study, we compared ground-dwelling beetle assemblages (Coleoptera) from a range of different oak fragments and surrounding conifer plantations to evaluate effects of forest size and surrounding matrix habitat in a temperate forest of north China. During 2000, beetles were sampled via pitfall traps within two large oak fragments (ca. 2.0-4.0 ha), two small oak fragments (ca. 0.2-0.4 ha) and two surrounding matrices dominated by pine plantations (>4 ha) in two sites of different aspects. Overall, no significantly negative effects from forest patch size and the surrounding matrix habitat were detected in total species number and abundance of ground-dwelling beetles. However, compared with small oak patches or pine plantations, more species were associated with an affinity for at least one large oak patch of the two aspects. Multivariate regression trees showed that the habitat type better determined the beetle assemblage structure than patch size and aspect, indicating a strong impact of the surrounding matrix. Linear mixed models indicated that species richness and abundance of all ground-dwelling beetles or beetle families showed different responses to the selected environmental variables. Our results suggest that more disturbed sites are significantly poorer in oak forest specialists, which are usually more abundant in large oak fragments and decrease in abundance or disappear in small fragments and surrounding matrix habitats. Thus, it is necessary to preserve a minimum size of forest patch to create conditions characteristic for forest interior, rather than the more difficult task of increasing habitat connectivity.

Elevational gradient in species richness pattern of epigaeic beetles and underlying mechanisms at east slope of Balang Mountain in southwestern China.

We report on the species richness patterns of epigaeic beetles (Coleoptera: Carabidae and Staphylinidae) along a subtropical elevational gradient of Balang Mountain, southwestern China. We tested the roles of environmental factors (e.g. temperature, area and litter cover) and direct biotic interactions (e.g. foods and antagonists) that shape elevational diversity gradients. Beetles were sampled at 19 sites using pitfall traps along the studied elevational gradient ranging from 1500 m-4000 m during the 2004 growing season. A total of 74416 specimens representing 260 species were recorded. Species richness of epigaeic beetles and two families showed unimodal patterns along the elevational gradient, peaking at mid-elevations (c. 2535 m), and the ranges of most beetle species were narrow along the gradient. The potential correlates of both species richness and environmental variables were examined using linear and second order polynomial regressions. The results showed that temperature, area and litter cover had strong explanatory power of beetle species richness for nearly all richness patterns, of beetles as a whole and of Carabidae and Staphylinidae, but the density of antagonists was associated with species richness of Carabidae only. Multiple regression analyses suggested that the three environmental factors combined contributed most to richness patterns for most taxa. The results suggest that environmental factors associated with temperature, area and habitat heterogeneity could account for most variation in richness pattern of epigaeic beetles. Additionally, the mid-elevation peaks and the small range size of most species indicate that conservation efforts should give attention to the entire gradient rather than just mid-elevations.

Effects of reforestation practices on Staphylinid beetles (Coleoptera: Staphylinidae) in Southwestern China forests.

In 2004, Staphylinid beetle (Coleoptera) assemblages were studied via pitfall trapping to examine the effects of reforestation in southwestern China forests. Sites included two 100-yr-old mature forest types (hemlock-spruce forest and birch forest), and three 40-yr-old forest types established after harvesting (spruce plantation, larch plantation, and natural broad-leaved forest). Staphylinid species richness was greater in natural broad-leaved forests than those in hemlock-spruce forests and spruce plantations, but no significant difference was found in abundance among the five forest types. Beetle assemblages from young forest stands were significantly different from those in older forest stands, and some environmental characteristics, i.e., elevation, proportion of broad-leaved trees, and coarse woody debris, significantly affected species abundances. Moreover, some staphylinid species predominantly found only in older forest stands indicate that mature forest specialists might be threatened by loss of habitat. So it is necessary to retain adequate patches of older successional stages for conserving these beetle assemblages.

[Species diversity of ground-dwelling beetles on northern slope of Daba Mountain, China].

By using pitfall trapping, the species composition and quantitative distribution of ground-dwelling beetles in man-made plantations in forest farm (MPFF), secondary natural forests in farmland (SFF), and man-made plantations in farmland (MPF) on northern slope of Daba Mountain were analyzed, and detrended correspondence analysis and cluster analysis were adopted to study the similarity of the species composition and quantitative distribution of the beetles among the three forest types. 1094 individuals of ground-dwelling beetles were captured in August 9-13th, 2002. Of these beetles, Staphylinidae and Chrysomelidae accounted for 40.59% and 33.18% of the total, respectively, and Carabidae, Leiodidae, Scarabaeidae, Curculionidae, Ptiliidae, and Pselaphidae each took more than 1% of the total. These eight families were considered as the common-occurring groups in the study area. The individuals of ground-dwelling beetles decreased from MPFF to SFF to MPF, and the family richness was obviously lower in MPF than in MPFF and SFF. The family composition and abundance of the beetles were significantly different between MPFF and SFF, but partial similarity was observed between MPF and other two forest types.

Distribution of carabid beetles (Coleoptera: Carabidae) across ecotones between regenerating and mature forests in southwestern China.

Edge effects resulting from logging on the distribution of carabid beetles (Coleoptera: Carabidae) were studied across ecotones between regenerating and mature forests established after harvesting of old-growth forests 20 yr prior to this study in southwestern China. Using pitfall traps, beetles were collected along five ecotone transects using nine samples with a distance interval of 25 m each. Although no significant differences were found in species richness and abundance of carabids among all three habitats, i.e., mature forest, young regenerating stand, and edge habitat, rarefaction estimates of species richness indicated that traps in young regenerating stands accumulated species faster than those on mature forest interiors and forest edges. Carabid species composition of the forest edges was more similar to those of the mature forest interiors than to those of the young regenerating stands. Variability in species composition was significantly reduced in young stands, suggesting that the carabid community from young stands is more homogeneous than the one from mature forests. Although most species occurred in all habitats, some species were significantly more abundant in mature forests and/or edges than in young stands. Results indicated that edge effects on forest carabids may persist for at least 20 yr after disturbance.

[The metabolic characteristics of isolated impaired fasting glucose and fasting hyperglycemia].

OBJECTIVE: To evaluate the metabolic characteristics of insulin secretion and insulin sensitivity in isolated impaired fasting glucose (iIFG) and isolated fasting hyperglycemia (IFH) and to clarify the factors responsible for the development of IFH. METHODS: Receiver operating characteristic curve (ROC) analysis was conducted in 1852 subjects. Three groups were classified according to a 75 g oral glucose tolerance test (OGTT): (1) normal glucose tolerance (NGT), n = 557; (2) iIFG, n = 221; (3) IFH, n = 81. The three groups were compared with insulin secretion (insulinogenic index) and insulin sensitivity (insulin sensitivity index). RESULTS: Using ROC analysis, the optimal cut point of fasting plasma glucose (FPG) related to diabetes diagnosis with OGTT was 6.695 mmol/L and the optimal cut point of FPG related to impaired glucose to lerance (IGT) diagnosis with OGTT was 5.590 mmol/L. From NGT to iIFG and IFH in these subjects, the insulinogenic index and insulin sensitivity index showed gradual decrease. CONCLUSION: Subjects with iIFG and IFH exhibit distinctly impaired early-phase insulin secretion and insulin sensitivity, indicating that both reduced insulin secretion and insulin resistance are the determinants of deterioration from NGT to iIFG and IFH.

Distribution of carabid beetles (Coleoptera: Carabidae) across a forest-grassland ecotone in southwestern China.

This paper studied the occurrence of carabid beetles (Coleoptera: Carabidae) in the forest edge, the adjacent forest interior, and the surrounding grassland in southwestern China. Beetles were collected with pitfall traps along five replicated transects. Forest species rarely penetrated into the grassland from the forest interior, and the grassland specialists were not found in the forest interior. The forest edge hosted additional species from the adjacent grassland that increased its overall species richness. Nearly all forest species (23 of 24 species) and grassland species (13 of 15 species) can be found in the forest edge. Carabids of the forest edge were more similar to those of the forest interior than to those of the grassland by ordination and cluster analysis. Based on the specificity and fidelity, carabids can be distinguished into five species groups: habitat generalists, grassland-associated species, forest generalists, forest specialists, and edge-associated species. Multiple linear regression analysis showed that canopy cover and/or shrub cover were the most important factors in determining the richness, abundance, and diversity of carabids. The forest edge may serve as a transition zone for dispersal and re-colonization of carabid beetles from adjacent habitats and therefore is important for natural conservation.

Microarray analysis of gene expression in Men1 knockout embryoid body reveals genetic events involved in early mouse embryonic development.

The Men1 gene has been identified as the gene responsible for MEN1, a hereditary syndrome transmitted with an autosomal dominant trait. Disruption of the Men1 gene results in defects of multiple organs development, including the nervous system, heart, liver, cranium, and face. In this study, we used embryoid bodies (EBs) formed from wild-type and Men1-/- ES cells as a model system to investigate effect of Men1 gene on the embryo development. We characterized in detail gene expression profile of these Men1-/- EBs by microarray techniques and identified a series of putative menin targeted genes, including genes involved in development of bone (e.g., Postn, Runx2, and Msx2), liver (e.g., KDR), blood (e.g., Hox9 and Kitl), and pancreatic islet (e.g., Sox4, Foxa1, Btc, Igf2, and Nfatc1). Further studies may shed light onto the underlying mechanisms of the interplay between menin and these genes.

[Identification of genes that are differentially expressed in omental fat of normal weight subjects, obese subjects and obese diabetic patients].

AIM: To identify genes that are differentially expressed in omental fat of normal weight subjects, obese subjects and obese type 2 diabetic patients. METHODS: Using a home-made high-density cDNA microarray, we compared gene expression profile of omental fat from normal weigh subjects, obese subjects and obese type 2 diabetic patients, to identify adipose-specific genes associated with obesity and diabetes. RESULTS: 119 and 257 genes were up-regulated in obese patients and obese diabetic patients respectively, while 46 and 58 genes were down-regulated in obese patients and obese diabetic patients respectively. 77 genes, including metabolism related genes (PDK4), and caveolin 2, metallo thionein 1B, were up-regulated in both obese and obese diabetic patients, while 8 genes, including key enzymes in lipid synthesis, such as HMG-CoA synthase, fatty acid synthase and stearoyl-CoA desaturase, were down-regulated in both groups. Another interesting finding was that tyrosine-3-monooxygenase/ tryptophan 5-monooxygenase activation protein theta (YWHAZ), a negative regulator for insulin signal transduction, was up-regulated only in obese diabetic patient, but not in normal-glycemic obese subjects. CONCLUSION: Our study demonstrated that decrease of lipogenesis along with increase of fatty acids oxidation of adipose tissue could be a common cause of insulin resistance in obesity and type 2 diabetes, while functional changes of other genes, such as immune regulation genes,might also be involved in the pathogenesis of obesity and type 2 diabetes. Block of insulin signal transduction might trigger the transition from obesity to diabetes. Further exploration of these genes will greatly help us in the understanding of the pathogenesis of obesity and type 2 diabetes.

Role and mechanism of rosiglitazone on the impairment of insulin secretion induced by free fatty acids on isolated rat islets.

BACKGROUND: Prolonged exposure of pancreatic beta-cells to fatty acids increases basal insulin secretion but inhibits glucose-stimulated insulin secretion. Rosiglitazone is a new antidiabetic agent of the thiazolidinediones. However, the relationship between thiazolidinediones and insulin secretion is highly controversial. The aim of this study is to explore the effect and mechanism of rosiglitazone on insulin secretion of islets under chronic exposure to free fatty acids (FFA). METHODS: Pancreatic islets were isolated from the pancreata of male Sprague-Dawley rats by the collagenase digestion and by the dextran gradient centrifugation method. The purified islets were cultured in the presence or absence of rosiglitazone and palmitate for 48 hours. The insulin secretion was measured by radioimmunoassay. The mRNA level of peroxisome proliferator-activated receptor gamma, uncoupling protein 2 (UCP-2) and insulin were determined by real-time polymerase chain reaction (PCR). The cell cytotoxicity assay was measured by cell counting kit-8. RESULTS: Islets exposed to elevated palmitate for 48 hours showed an increased basal and a decreased glucose-stimulated insulin secretion (P < 0.01). The mRNA level of UCP-2 was increased by 3.7 fold in the 0.5 mmol/L concentration of palmitate. When islets were cultured with palmitate (0.5 mmol/L) in the presence of rosiglitazone (1.0 micromol/L), both basal and glucose-stimulated insulin secretion reversed to a pattern of control islets (P < 0.05, P < 0.01). The addition of rosiglitazone in the culture medium decreased the mRNA level of UCP-2 by 2.2 fold, having a statistically significant difference (P < 0.05) as compared with islets cultured with palmitate alone. The cell viability was not affected. CONCLUSION: The protective effects of rosiglitazone on insulin secretion of isolated pancreatic islets under chronic exposure to palmitate might be mediated through the downregulation of UCP-2 expression.

[Absence of evidence for the association of single nucleotide polymorphisms in Annexin A1 gene with type 2 diabetes in Chinese].

OBJECTIVE: To identify single nucleotide polymorphisms (SNPs) in the annexin A1(ANXA1) gene and to analyze the association of these SNPs with type 2 diabetes in Shanghai Han population. METHODS: SNPs in the promotor and exon regions (including intron sequence near splicing site) in the ANXA1 gene were screened by direct sequencing in 24 type 2 diabetes patients and were further genotyped by direct sequencing in another 171 type 2 diabetes patients and 189 normal control subjects. RESULTS: The total sequence of ANXA1 gene is 6798 bp. And 7 SNPs were found; among them, 2 SNPs (-7974 C>T and -7040 G>T) were in promotor region, 3 SNPs in intron regions (+9059 A>G, +9204 C>T, +10486 A>G), 1 SNP in 5'-untranslation region (-6614 A>G) and 1 SNP in coding regions (+1784 A>G). These 7 SNPs were genotyped further and the results revealed that the allele frequencies of these SNPs showed no significant difference between the diabetic and the control groups (P>0.05). CONCLUSION: There is no association of these SNPs in ANXA1 gene with type 2 diabetes in Shanghai Han population.

[Clinical and molecular research in a case of familial Carney complex].

OBJECTIVE: A case of primary pigmented nodular adrenal disease (PPNAD) was first diagnosed in Ruijin Hospital, Shanghai, China and molecular genetic research was then carried on the proband and his family members. METHODS: History and laboratory tests were routinely taken. Liddle's test, adrenal CT and pituitary magnetic resonance imaging were also carried out. Complete family history was obtained and eight of the family members donated their blood for DNA extraction. Polymerase chain reaction was done on all the exons of PRKAR1A gene and the product of the reaction was sequenced with ABI 3700. The right adrenal of the patient was then resected, part of the tissue was preserved in liquid nitrogen for DNA/RNA extraction and the remaining sent to Department of Pathology. RESULTS: The patient presented an atypical appearance of Cushing's syndrome. His father had a typical history of cardiac myoma. Cortisone level could not be refrained in Liddle's test for the patient. Imaging examination presented a nodular adrenal and a full pituitary. A novel mutation of PRKAR1A-S147N was found in both the patient's and his father's gene. CONCLUSIONS: This is the first patient diagnosed as PPNAD based on his clinical manifestations, laboratory tests and imaging and pathological examinations. According to the history of his father and the results of molecular genetic analysis, the diagnosis of Carney complex can be established on this patient and his father. It is also the first time that this kind of point mutation was found in Chinese people.