Temporal Variation in Trophic Cascades

The trophic cascade has emerged as a key paradigm in ecology. Although ecologists have made progress in understanding spatial variation in the strength of trophic cascades, temporal variation remains relatively unexplored. Our review suggests that strong trophic cascades are often transient, appearing when ecological conditions support high consumer abundance and rapidly growing, highly edible prey. Persistent top-down control is expected to decay over time in the absence of external drivers, as strong top-down control favors the emergence of better-defended resources. Temporal shifts in cascade strength—including those driven by contemporary global change—can either stabilize or destabilize ecological communities. We suggest that a more temporally explicit approach can improve our ability to explain the drivers of trophic cascades and predict the impact of changing cascade strength on community dynamics.

[Effects of pretreatment with dimethyloxalylglycine on the survival of multi-territory perforator flap in rat and related mechanism]

OBJECTIVE

To observe the effects of pretreatment with dimethyloxalylglycine (DMOG) on the survival of multi-territory perforator flap and the vessels of choke zone (CZ) 2 in rat, and to explore related mechanism.

METHODS

Sixty adult SD rats were divided into group DMOG and normal saline group (NS) according to the random number table, with 30 rats in each group. Perforator flap with three angiosomes was made on the right dorsal side of rat, including deep iliac circumflex artery perforator, intercostal artery perforator, thoracodorsal artery perforator, as well as CZ 1 and CZ 2. Rats in group DMOG were intraperitoneally injected with 2 mL NS containing DMOG (40 mg/kg) 2 days before operation, 2 hours before operation, and 2 days after operation. Rats in group NS were intraperitoneally injected with equivalent volume of NS at the same time point. On post operation day (POD) 7, gross observation was conducted, and the survival rate of flap was calculated. On POD 7, the vascularity in CZ 2 and potential zone of flap was observed using angiography. On POD 7, new vessel in CZ 2 of flap was observed with HE staining, and the microvessel density (MVD) was calculated. On POD 7, the expression of vascular endothelial growth factor (VEGF) in CZ 2 of flap was detected by immunohistochemistry and Western blotting (respectively denoted as integral absorbance values and ratio of gray value), and blood flow volume of vessel in CZ 2 of flap was examined by laser Doppler perfusion imager. The sample number of each index was 6 in each group. Data were processed with t test.

RESULTS

(1) On POD 7, rats in two groups all survived, and the flaps were not infected. In group DMOG, the necrotic area of flaps of rats with dark yellow crust and soft texture was observed approximately at the distal end of skin entry point of thoracodorsal artery perforator. In group NS, the necrotic area of flaps of rats with brownish black crust and hard texture was observed approximately at the distal end of CZ 2. The survival rate of flap of rats in group DMOG was (88±3) %, which was significantly higher than that in group NS [(82±3) %, t=3.38, P<0.01]. (2) On POD 7, there were clear vascular structure and many new vessels in CZ 2 of flaps of rats in group DMOG, with intact vascular structure in potential zone. On POD 7, there were unclear vascular structure and few new vessels in CZ 2 of flaps of rats in group NS, with disorder vascular structure in potential zone. (3) On POD 7, MVD in CZ 2 of flaps in rats of group DMOG was (29.2±2.2)/mm(2,) which was significantly higher than that of group NS [(20.3±3.6)/mm(2,) t=5.10, P<0.01]. (4) On POD 7, the expressions of VEGF in CZ 2 of flaps in rats of group DMOG detected by immunohistochemistry and Western blotting were 5 060±432 and 0.48±0.04 respectively, which were significantly higher than those of group NS (2 811±382 and 0.26±0.06, with t values respectively 9.54 and 5.67, P values below 0.01). (5) On POD 7, blood flow volume of vessel in CZ 2 of flaps in rats of group DMOG was (58±4) perfusion units (PU), which was significantly more than that of group NS [(46±4) PU, t=5.20, P<0.01].

CONCLUSIONS

DMOG can increase the survival rate of multi-territory perforator flap through promoting angiogenesis in CZ 2 of flap on the back of rat and improving blood supply of flap.

[Clinical study on the relations of obstructive sleep apnea hypopneasyndrome and the degree and prognosis of coronary lesions]

Objective:The aim of this study is to discuss the relations between obstructive sleep apnea hypopnea syndrome (OSAHS) and severity and prognosis of coronary artery disease. Method:The OSAHS patients were divided into mild, moderate and severe groups according to Results of sleep monitoring. The severity of coronary artery lesion in each group was compared by counting the numbers of the lesion extension of coronary artery, calculating the Gensin score and evaluating the Thromblysis in myocardial infarction. The patients were followed up within 2 years, the incidence of major clinical cardiac adverse events was compared between each groups. Result:Three groups confirmed the numbers of the lesion extension of coronary artery and Gensin score increased, the Thromblysis in myocardial infarction reduced with the seriousness of OSAHS by coronary angiography (P<0.05). There was no statistical significance in compliance for oral use of three groups (P>0.05). Incidence of the main adverse cardiac events during two years in three groups were16.28%, 29.36% and 44.26%. Incidence of the main adverse cardiac events increased with the seriousness of OSAHS (P<0.05). Conclusion:The coronary artery pathologic change severity aggravated with the seriousness of OSAHS，and the incidence of the main adverse cardiac events increased with the seriousness of OSAHS.

[Construction of the pIRES2-ZsGreen1 eukaryotic expression vector of Factor Ⅸ gene and expression in HEK-293 cells]

目的

以含有凝血因子Ⅸ（FⅨ）cDNA的pcDNA/FⅨ质粒为模板构建真核表达载体pIRES2-ZsGreen1/FⅨ并检测其在HEK-293细胞中的表达。

方法

以pcDNA/FⅨ质粒为模板，扩增出目的基因FⅨ的开放阅读框（ORF）区，使用Infusion酶对线性pIRES2-ZsGreen1双酶切产物及FⅨORF扩增产物进行连接，连接产物进行转化后筛选阳性克隆，对阳性克隆进行DNA测序及凝胶电泳鉴定。野生型pIRES2-ZsGreen1/FⅨ转染HEK-293细胞后，分别采用实时定量PCR、细胞免疫荧光法、一期法检测野生型FⅨ基因mRNA表达水平、蛋白的表达量及细胞裂解液、细胞培养液的FⅨ活性。

结果

成功构建pIRES2-ZsGreen1/FⅨ并转染HEK-293细胞，实时定量PCR证实HEK-293细胞表达FⅨ mRNA，激光共聚焦显微镜下观察到FⅨ蛋白在细胞质中合成，野生型质粒pIRES2-ZsGreen1/FⅨ转染HEK-293细胞裂解液和细胞培养液的FⅨ活性分别为（92.03±0.29）%、（86.89±8.78）%，无转染的HEK-293细胞裂解液和培养液中FⅨ活性均为0。

结论

成功构建FⅨ野生型pIRES2-ZsGreen1真核表达载体。

[An investigation of prevalence of occupational diseases and treatment implementation in migrant workers in Hunan, China]

Objective: To investigate the prevalence of occupational diseases and treatment implementation in migrant workers in Hunan, China, and to provide a scientific basis for related departments to develop preventive and treatment measures and social security system for migrant workers. Methods: A retrospective investigation was performed in 2015 to collect the information of occupational diseases in migrant workers, and age, type of work, type of occupational disease, and implementation of employment injury insurance for occupation diseases were analyzed. Results: The migrant workers with occupational diseases accounted for 50.43% (11 280/22 368) of all patients with occupational diseases in Hunan, among whom 99.4% (11 212/11 280) were male workers. The mean age of migrant workers with occupational diseases was 55 years. The types of occupational diseases involved 6 categories such as occupational pneumoconiosis and occupational skin diseases, totaling 42 legal occupational diseases; 98.31% of all migrant workers (11 089/11 280) had occupational pneumoconiosis. The main types of work were underground coal miners (62.42%) , heading drivers (29.79%) , and haulage workers (2.20%) in coal mines and non-coal mines. A total of 27.25% migrant workers with occupational diseases (2 072/7 605) enjoyed employment injury insurance, and 20.84% (1 585/7 605) did not receive any medical or life compensations. Conclusion: The occupational diseases in migrant workers in Hunan are mainly pneumoconiosis, and a large proportion of those with occupational diseases do not enjoy implementation of treatment. Coal mines and non-coal mines are the high-risk areas for occupational diseases in migrant workers and should be the focus of prevention and control.

[A multi-center clinical observation on safety and efficacy of a plasma derived coagulator factor Ⅷ for treatment of patients with hemophilia A]

OBJECTIVE

To evaluate the efficacy and safety of homemade plasma derived coagulation factor Ⅷ in patients with hemophilia A.

METHODS

Patients with congenital hemophilia A who met the inclusive and exclusive criteria were enrolled in the study after informed consent. The doses of factor Ⅷ were calculated according to the weight, disease severity etc. FⅧ activity and infusion efficacy value at 10 min and 60 min after infusion were recorded, as well as adverse events and validity rating according to the improvement of clinical syndromes. Viral infections including HBV, HCV, HIV and FⅧ inhibitor were determined after 3 and 6 months.

RESULTS

A total of 65 patients were enrolled in this study, all of whom were evaluable for drug safety. Treatment efficacy was evaluated in 60 patients and 57 cases completed the trial finally. In this 57 cases, most (52/57) subjects were of middle and severe hemophilia A mainly characterized by joint bleeding. Overall response rate of acute bleeding events was classified as "excellent" (70.00%) or "better" (30.00%). The non-responder was 0. FⅧ activity and infusion efficiency value of first administration after 10 min and 60 min improved significantly [10 min: (123.66±47.54)%; 60 min: (108.05±43.24)%]. The incidence of adverse events was 1.54%. Neither allergic reaction nor reactivation of HBV, HCV, HIV was detected after treatment of 3 and 6 months. No FⅧ inhibitor negative patients converted to positive during follow-up.

CONCLUSION

This homemade plasma derived coagulation factor Ⅷ is safe and effective for the treatment of acute bleeding in patients with hemophilia A.

Grassland productivity limited by multiple nutrients

Terrestrial ecosystem productivity is widely accepted to be nutrient limited(1). Although nitrogen (N) is deemed a key determinant of aboveground net primary production (ANPP)(2,3), the prevalence of co-limitation by N and phosphorus (P) is increasingly recognized(4-8). However, the extent to which terrestrial productivity is co-limited by nutrients other than N and P has remained unclear. Here, we report results from a standardized factorial nutrient addition experiment, in which we added N, P and potassium (K) combined with a selection of micronutrients (K+μ), alone or in concert, to 42 grassland sites spanning five continents, and monitored ANPP. Nutrient availability limited productivity at 31 of the 42 grassland sites. And pairwise combinations of N, P, and K+μ co-limited ANPP at 29 of the sites. Nitrogen limitation peaked in cool, high latitude sites. Our findings highlight the importance of less studied nutrients, such as K and micronutrients, for grassland productivity, and point to significant variations in the type and degree of nutrient limitation. We suggest that multiple-nutrient constraints must be considered when assessing the ecosystem-scale consequences of nutrient enrichment.

[Clinical significance of high expression with UTX in renal cell carcinoma]

OBJECTIVE

To investigate the expression and significance of ubiquitously transcribed TPR gene on the X chromosome (UTX) in renal cell carcinoma (RCC) tissues, then to explore the relationship between UTX expression and renal cancer pathologic characteristics.

METHODS

In the study, 45 patients with dignosed renal cell carcinoma clinical samples were collected in Peking University Shenzhen Hospital. Total RNA and protein were extracted from the cancer tissues and adjacent normal tissues. UTX expression of cancer tissues and adjacent normal tissues was detected on both mRNA and protein levels using real time-PCR and IHC, respectively. And the relationship between UTX expression and the 45 patients' clinical characteristics was analyzed.

RESULTS

The mRNA level of UTX in cancer tissues(C) was 4.4 folds, higher than that of the adjacent normal tissues(N) [ 0.883 2±0.703 8 vs. 0.199 7±0.140 0, P<0.05]. The protein expression of UTX in cancer tissues was up-regulated, and the protein score of cancer tissues was 4 folds, change compared with adjacent normal tissues[12±4 vs. 3±3, P<0.05].The expression of UTX was associated with pathological grade(P=0.004)but without gender, age, tumor size and TNM stage.

CONCLUSION

UTX is up-regulated in RCC tissues and the expression of UTX is associated with pathological grade, illustrating that UTX may play an important role in renal cancer progression.

Co-occurrence of psychotic experiences and common mental health conditions across four racially and ethnically diverse population samples

BACKGROUND

Prior research with racially/ethnically homogeneous samples has demonstrated widespread co-occurrence of psychotic experiences (PEs) and common mental health conditions, particularly multi-morbidity, suggesting that psychosis may be related to the overall severity of psychiatric disorder rather than any specific subtype. In this study we aimed to examine whether PEs are associated with the presence of specific disorders or multi-morbidity of co-occurring disorders across four large racially/ethnically diverse samples of adults in the USA.

METHOD

Data were drawn from the National Comorbidity Survey Replication (NCS-R), the National Survey of American Life (NSAL) and separately from the Asian and Latino subsamples of the National Latino and Asian American Study (NLAAS). Logistic regression models were used to examine the relationship between PEs and individual subtypes of DSM-IV disorder, and to test for a linear dose-response relationship between the number of subtypes and PEs.

RESULTS

Prevalence of PEs was moderately greater among individuals with each subtype of disorder in each data set [odds ratios (ORs) 1.8-3.8], although associations were only variably significant when controlling for clinical and demographic variables. However, the sum of disorder subtypes was related to odds for PEs in a linear dose-response fashion across all four samples.

CONCLUSIONS

PEs are related primarily to the extent or severity of psychiatric illness, as indicated by the presence of multiple psychiatric disorders, rather than to any particular subtype of disorder in these data. This relationship applies to the general population and across diverse racial/ethnic groups.

Insects as drivers of ecosystem processes

Insects and other small invertebrates are ubiquitous components of all terrestrial and freshwater food webs, but their cumulative biomass is small relative to plants and microbes. As a result, it is often assumed that these animals make relatively minor contributions to ecosystem processes. Despite their small sizes and cumulative biomass, we suggest that these animals may commonly have important effects on carbon and nutrient cycling by modulating the quality and quantity of resources that enter the detrital food web, with consequences at the ecosystem level. These effects can occur through multiple pathways, including direct inputs of insect biomass, the transformation of detrital biomass, and the indirect effects of predators on herbivores and detritivores. In virtually all cases, the ecosystem effects of these pathways are ultimately mediated through interactions with plants and soil microbes. Merging our understanding of insect, plant and microbial ecology will offer a valuable way to better integrate community-level interactions with ecosystem processes.

The effect of chronic seaweed subsidies on herbivory: plant-mediated fertilization pathway overshadows lizard-mediated predator pathways

Flows of energy and materials link ecosystems worldwide and have important consequences for the structure of ecological communities. While these resource subsidies typically enter recipient food webs through multiple channels, most previous studies focussed on a single pathway of resource input. We used path analysis to evaluate multiple pathways connecting chronic marine resource inputs (in the form of seaweed deposits) and herbivory in a shoreline terrestrial ecosystem. We found statistical support for a fertilization effect (seaweed increased foliar nitrogen content, leading to greater herbivory) and a lizard numerical response effect (seaweed increased lizard densities, leading to reduced herbivory), but not for a lizard diet-shift effect (seaweed increased the proportion of marine-derived prey in lizard diets, but lizard diet was not strongly associated with herbivory). Greater seaweed abundance was associated with greater herbivory, and the fertilization effect was larger than the combined lizard effects. Thus, the bottom-up, plant-mediated effect of fertilization on herbivory overshadowed the top-down effects of lizard predators. These results, from unmanipulated shoreline plots with persistent differences in chronic seaweed deposition, differ from those of a previous experimental study of the short-term effects of a pulse of seaweed deposition: while the increase in herbivory in response to chronic seaweed deposition was due to the fertilization effect, the short-term increase in herbivory in response to a pulse of seaweed deposition was due to the lizard diet-shift effect. This contrast highlights the importance of the temporal pattern of resource inputs in determining the mechanism of community response to resource subsidies.

Drosophila regulate yeast density and increase yeast community similarity in a natural substrate

Drosophila melanogaster adults and larvae, but especially larvae, had profound effects on the densities and community structure of yeasts that developed in banana fruits. Pieces of fruit exposed to adult female flies previously fed fly-conditioned bananas developed higher yeast densities than pieces of the same fruits that were not exposed to flies, supporting previous suggestions that adult Drosophila vector yeasts to new substrates. However, larvae alone had dramatic effects on yeast density and species composition. When yeast densities were compared in pieces of the same fruits assigned to different treatments, fruits that developed low yeast densities in the absence of flies developed significantly higher yeast densities when exposed to larvae. Across all of the fruits, larvae regulated yeast densities within narrow limits, as compared to a much wider range of yeast densities that developed in pieces of the same fruits not exposed to flies. Larvae also affected yeast species composition, dramatically reducing species diversity across fruits, reducing variation in yeast communities from one fruit to the next (beta diversity), and encouraging the consistent development of a yeast community composed of three species of yeast (Candida californica, C. zemplinina, and Pichia kluvyeri), all of which were palatable to larvae. Larvae excreted viable cells of these three yeast species in their fecal pools, and discouraged the growth of filamentous fungi, processes which may have contributed to their effects on the yeast communities in banana fruits. These and other findings suggest that D. melanogaster adults and their larval offspring together engage in 'niche construction', facilitating a predictable microbial environment in the fruit substrates in which the larvae live and develop.

Complex consequences of herbivory and interplant cues in three annual plants

Information exchange (or signaling) between plants following herbivore damage has recently been shown to affect plant responses to herbivory in relatively simple natural systems. In a large, manipulative field study using three annual plant species (Achyrachaena mollis, Lupinus nanus, and Sinapis arvensis), we tested whether experimental damage to a neighboring conspecific affected a plant's lifetime fitness and interactions with herbivores. By manipulating relatedness between plants, we assessed whether genetic relatedness of neighboring individuals influenced the outcome of having a damaged neighbor. Additionally, in laboratory feeding assays, we assessed whether damage to a neighboring plant specifically affected palatability to a generalist herbivore and, for S. arvensis, a specialist herbivore. Our study suggested a high level of contingency in the outcomes of plant signaling. For example, in the field, damaging a neighbor resulted in greater herbivory to A. mollis, but only when the damaged neighbor was a close relative. Similarly, in laboratory trials, the palatability of S. arvensis to a generalist herbivore increased after the plant was exposed to a damaged neighbor, while palatability to a specialist herbivore decreased. Across all species, damage to a neighbor resulted in decreased lifetime fitness, but only if neighbors were closely related. These results suggest that the outcomes of plant signaling within multi-species neighborhoods may be far more context-specific than has been previously shown. In particular, our study shows that herbivore interactions and signaling between plants are contingent on the genetic relationship between neighboring plants. Many factors affect the outcomes of plant signaling, and studies that clarify these factors will be necessary in order to assess the role of plant information exchange about herbivory in natural systems.

Productivity is a poor predictor of plant species richness

For more than 30 years, the relationship between net primary productivity and species richness has generated intense debate in ecology about the processes regulating local diversity. The original view, which is still widely accepted, holds that the relationship is hump-shaped, with richness first rising and then declining with increasing productivity. Although recent meta-analyses questioned the generality of hump-shaped patterns, these syntheses have been criticized for failing to account for methodological differences among studies. We addressed such concerns by conducting standardized sampling in 48 herbaceous-dominated plant communities on five continents. We found no clear relationship between productivity and fine-scale (meters(-2)) richness within sites, within regions, or across the globe. Ecologists should focus on fresh, mechanistic approaches to understanding the multivariate links between productivity and richness.

Behavior as a key component of integrative biology in a human-altered world

A major grand challenge in biology is to understand the interactions between an organism and its environment. Behavior resides in the central core of this association as it affects and is affected by development, physiology, ecological dynamics, environmental choice, and evolution. We present this central role of behavior in a diagram illustrating the multifaceted program emphasizing the necessity for understanding this nexus and to fully appreciate the organism in its environment given the ongoing changes affected by contemporary human induced, rapid environmental change (HIREC). We call for the consideration of educational and research focuses to concentrate on the interdisciplinary role that behavior plays in the integration of biological processes.

Marine subsidies have multiple effects on coastal food webs

The effect of resource subsidies on recipient food webs has received much recent attention. The purpose of this study was to measure the effects of significant seasonal seaweed deposition events, caused by hurricanes and other storms, on species inhabiting subtropical islands. The seaweed represents a pulsed resource subsidy that is consumed by amphipods and flies, which are eaten by lizards and predatory arthropods, which in turn consume terrestrial herbivores. Additionally, seaweed decomposes directly into the soil under plants. We added seaweed to six shoreline plots and removed seaweed from six other plots for three months; all plots were repeatedly monitored for 12 months after the initial manipulation. Lizard density (Anolis sagrei) responded rapidly, and the overall average was 63% higher in subsidized than in removal plots. Stable-isotope analysis revealed a shift in lizard diet composition toward more marine-based prey in subsidized plots. Leaf damage was 70% higher in subsidized than in removal plots after eight months, but subsequent damage was about the same in the two treatments. Foliage growth rate was 70% higher in subsidized plots after 12 months. Results of a complementary study on the relationship between natural variation in marine subsidies and island food web components were consistent with the experimental results. We suggest two causal pathways for the effects of marine subsidies on terrestrial plants: (1) the "fertilization effect" in which seaweed adds nutrients to plants, increasing their growth rate, and (2) the "predator diet shift effect" in which lizards shift from eating local prey (including terrestrial herbivores) to eating mostly marine detritivores.

Pulses of dead periodical cicadas increase herbivory of American bellflowers

Resource pulses can have both direct bottom-up and indirect top-down effects on their consumers, but comparatively few studies have investigated the top-down effects of naturally occurring resource pulses on plants. This study describes two years of field experiments conducted to determine the indirect effects of 17-year periodical cicadas (Magicicada spp.) on herbivory in American bellflowers (Campanulastrum americanum). In 2004, the area of damaged leaves on cicada-supplemented plants was 78% greater than the area of damaged leaves on control plants. In 2005, cicada-supplemented plants were more likely to experience herbivory by mammalian herbivores than control plants. When large herbivores were excluded, similar patterns of leaf herbivory were observed, but these differences were not statistically significant. These results suggest that the pulsed input of dead periodical cicada bodies increased rates of herbivory on bellflowers, and that this effect was largely mediated by the selective foraging of large mammalian herbivores. More broadly, this study suggests that pulses of limiting resources can have both positive direct effects on plants and negative indirect effects due to selective herbivory, and that the net effects of pulsed resources on plants may depend on the composition and behavior of the surrounding herbivore community.

Patients with chronic hepatitis B infection: what is their quality of life?

INTRODUCTION

Hepatitis B (HBV) is endemic in Singapore. This study aimed to determine the quality of life of patients with chronic HBV infection (HBV carriers) on conservative management. They were reviewed in primary care facilities and in a district hospital in Singapore.

METHODS

This cross-sectional survey utilised a validated Hepatitis Quality of Life questionnaire, which incorporated the SF-36 health survey, to assess a convenience sample of HBV carriers' quality of life in 14 domains. The mean scores in each domain were determined, with higher scores indicating better health. Wilcoxon-Mann-Whitney test was used in the data analysis to determine statistical significance (p-value is less than 0.05).

RESULTS

The mean age of 108 participants was 44.1 (standard deviation 12.5) years. They were predominantly Chinese (90.7 percent), male (58.3 percent) and 50.7 percent of them had family members who were HBV-infected. The latter had higher scores in the hepatitis specific limitation (HLIM) domain. The majority did not have any impaired physical nor mental health. In comparison with the healthy peers in the local population, the Chinese HBV carriers scored significantly lower in the "social functioning" domain (p-value is less than 0.001), regardless of gender.

CONCLUSION

The majority of HBV carriers had good physical and mental health. Physicians should recognise the impact of the chronic infection on the social aspects of daily living of the HBV carriers, and such issues should be addressed appropriately to provide better quality care.

What can we learn from resource pulses?

An increasing number of studies in a wide range of natural systems have investigated how pulses of resource availability influence ecological processes at individual, population, and community levels. Taken together, these studies suggest that some common processes may underlie pulsed resource dynamics in a wide diversity of systems. Developing a common framework of terms and concepts for the study of resource pulses may facilitate greater synthesis among these apparently disparate systems. Here, we propose a general definition of the resource pulse concept, outline some common patterns in the causes and consequences of resource pulses, and suggest a few key questions for future investigations. We define resource pulses as episodes of increased resource availability in space and time that combine low frequency (rarity), large magnitude (intensity), and short duration (brevity), and emphasize the importance of considering resource pulses at spatial and temporal scales relevant to specific resource-onsumer interactions. Although resource pulses are uncommon events for consumers in specific systems, our review of the existing literature suggests that pulsed resource dynamics are actually widespread phenomena in nature. Resource pulses often result from climatic and environmental factors, processes of spatiotemporal accumulation and release, outbreak population dynamics, or a combination of these factors. These events can affect life history traits and behavior at the level of individual consumers, numerical responses at the population level, and indirect effects at the community level. Consumers show strategies for utilizing ephemeral resources opportunistically, reducing resource variability by averaging over larger spatial scales, and tolerating extended interpulse periods of reduced resource availability. Resource pulses can also create persistent effects in communities through several mechanisms. We suggest that the study of resource pulses provides opportunities to understand the dynamics of many specific systems, and may also contribute to broader ecological questions at individual, population, and community levels.

Design of spintronic materials with simple structures

A brief comparison of conventional electronics and spintronics is given. The key features of half metallic binary compounds with the zincblende structure are presented, using MnAs as an example. We discuss the interactions responsible for the half metallic properties. Special properties of superlattices and a digital ferromagnetic heterostructure incorporating zincblende half metals are also discussed.

Antifouling and antibacterial compounds from the gorgonians Subergorgia suberosa and Scripearia gracillis

In this study, we investigated the potential antilarval and antibacterial activity of secondary metabolites of the gorgonians Subergorgia suberosa and Scripearia gracillis from the South China Sea. Fresh specimens of these two gorgonian corals were collected from a shallow reef in Sanya Bay of Hainan Island and extracted with different solvents. Antilarval activity of the chemical extracts and pure compounds was evaluated in settlement inhibition assays with laboratory-reared Balanus amphitrite and Bugula neritina larvae, while antibacterial activity was assessed with disc diffusion bioassay on growth inhibition of 15 marine bacterial species. Using bioassay-guided procedures, we purified and identified nine compounds. The most potent metabolites produced by these gorgonian corals were subergorgic acid and pregn-4-ene-3, 20-dione extracted from S. suberosa. Our results show that the gorgonian coral S. suberosa and S. gracillis can produce potent anti-fouling compounds that deserve further exploration.

Application of mental illness stigma theory to Chinese societies: synthesis and new directions

The rapidly-evolving literature concerning stigma towards psychiatric illnesses among Chinese groups has demonstrated pervasive negative attitudes and discriminatory treatment towards people with mental illness. However, a systematic integration of current stigma theories and empirical findings to examine how stigma processes may occur among Chinese ethnic groups has yet to be undertaken. This paper first introduces several major stigma models, and specifies how these models provide a theoretical basis as to how stigma broadly acts on individuals with schizophrenia through three main mechanisms: direct individual discrimination, internalisation of negative stereotypes, and structural discrimination. In Chinese societies, the particular manifestations of stigma associated with schizophrenia are shaped by cultural meanings embedded within Confucianism, the centrality of "face", and pejorative aetiological beliefs of mental illnesses. These cultural meanings are reflected in severe and culturally-specific expressions of stigma in Chinese societies. Implications and directions to advance stigma research within Chinese cultural settings are provided.

Effect of agitation on violacein production in Pseudoalteromonas luteoviolacea isolated from a marine sponge

AIMS

Experiments were designed to investigate the effect of agitation on the production of violacein by a marine bacterium Pseudoalteromonas luteoviolacea.

METHODS AND RESULTS

A marine sponge-associated bacterium, P. luteoviolacea, was grown at different agitation speeds. Agitation did not have a significant effect on bacterial growth, but had a profound effect on the size of bacterial aggregate. The production of violacein was the highest under stagnant conditions and decreased with the increase of the agitation speed.

CONCLUSIONS

Agitation affected the aggregation of bacterial cells, which, in turn, affected violacein production by P. luteoviolacea.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study suggests that P. luteoviolacea produced the highest amount of violacein when it was cultured under stagnant conditions.

Periodical cicadas use light for oviposition site selection

Organisms use incomplete information from local experience to assess the suitability of potential habitat sites over a wide range of spatial and temporal scales. Although ecologists have long recognized the importance of spatial scales in habitat selection, few studies have investigated the temporal scales of habitat selection. In particular, cues in the immediate environment may commonly provide indirect information about future habitat quality. In periodical cicadas (Magicicada spp.), oviposition site selection represents a very long-term habitat choice. Adult female cicadas insert eggs into tree branches during a few weeks in the summer of emergence, but their oviposition choices determine the underground habitats of root-feeding nymphs over the following 13 or 17 years. Here, field experiments are used to show that female cicadas use the local light environment of host trees during the summer of emergence to select long-term host trees. Light environments may also influence oviposition microsite selection within hosts, suggesting a potential behavioural mechanism for associating solar cues with host trees. In contrast, experimental nutrient enrichment of host trees did not influence cicada oviposition densities. These findings suggest that the light environments around host trees may provide a robust predictor of host tree quality in the near future. This habitat selection may influence the spatial distribution of several cicada-mediated ecological processes in eastern North American forests.

Influence of soil chemistry on metal and bioessential element concentrations in nymphal and adult periodical cicadas (Magicicada spp.)

Metal and bioessential element concentrations were measured in three species of 17-year periodical cicadas (Magicicada spp.) to determine how cicada tissue chemistry is affected by soil chemistry, measure the bioavailability of metals from both uncontaminated and lead-arsenate-pesticide contaminated soils, and assess the potential risks of observed metal contamination for wildlife. Periodical cicada nymphs feed on root xylem fluids for 13 or 17 years of underground development. The nymphs then emerge synchronously at high densities, before leaving their nymphal keratin exoskeleton and molting into their adult form. Cicadas are an important food source for birds and animals during emergence events, and influence nutrient cycles in woodland ecosystems. Nymphal exoskeletons and whole adult cicadas were sampled in Clarke and Frederick Counties, Virginia and Berkeley and Jefferson Counties, West Virginia during the Brood X emergence in May and June, 2004. Elements, such as Al, Fe, and Pb, are strongly enriched in the nymphal exoskeleton relative to the adult body; Cu and Zn are enriched in bodies. Concentrations of Fe and Pb, when normalized to relatively inert soil constituents such as Al and Ce, are similar in both the molt exoskeleton and their host soil, implying that passive assimilation through prolonged soil contact (adhesion or adsorption) might control these metal concentrations. Normalized concentrations of bioessential elements, such as S, P, K, Ca, Mn, Cu, Zn, and Mo, and chalcophile (sulfur-loving) elements, such as As, Se, and Au, indicate strong enrichment in cicada tissues relative to soil, implying selective absorption and retention by xylem fluids, the cicada nymphs themselves, or both. Element enrichment patterns in cicada tissues are similar to enrichment patterns observed in xylem fluids from tree roots. Chalcophile elements and heavy metals accumulate in keratin-rich tissues and may bind to sulfhydryl groups. Metal concentrations in the nymphal exoskeleton show a positive correlation with soil metal concentrations, with Au exhibiting particularly strong enrichment in the exoskeleton relative to soil concentrations. Metal concentrations in adult bodies do not correlate with soil chemistry. Bioessential elements S, Ca, Mn, Fe, and Zn differed by sex in adults, whereas Na, Mg, K, Ca, Mn, Fe, Zn, and As differed by species. Body concentrations of Ca differed by site conditions (orchard or reference setting). The high Pb contents of orchard soils contaminated by arsenical pesticide residues might inhibit Ca uptake by cicada nymphs. The adult cicadas contain concentrations of metals similar to, or less than, other invertebrates, such as earthworms. There does not appear to be a dietary threat to birds or other consumers of adult cicadas based on Maximum Tolerable Dietary Level (MTDL) Guidelines developed for agricultural animals.

[Significance of hepatitis B virus PreS1-Ag, PreS2-Ag, large protein, PreS2-Ab detection and the prediction of HBV DNA replication.]

BACKGROUND

To explore the significance of hepatitis B virus PreS1-Ag, PreS2-Ag, large protein (LP) detection and the prediction of viral replication.

METHODS

PreS1-Ag, PreS2-Ag, LP and HBV markers were measured by enzyme linked immunosorbent assay (ELISA) in 201 cases of infected serum. Serum HBV DNA level was quantitatively detected by real-time polymerase chain reaction (PCR).

RESULTS

There were significant differences in positive rate between the PreS1-Ag, PreS2-Ag, LP, and HBsAg; the positive rate of PreS2-Ag and LP were higher than that of the HBeAg. No significant differences were found in the positive rates between LP and the levels of HBV DNA and there was a positive correlation between quantitations of HBV DNA and HBV-LP.

CONCLUSION

Serum PreS1-Ag, PreS2-Ag and LP were laboratory markers that can accurately reflect HBV DNA reproduction, and were helpful complementarity to traditional HBV M. There is a close correlation between the number of copies of HBV DNA and the levels of HBV-LP.

Half-metallic digital ferromagnetic heterostructure composed of a delta-doped layer of Mn in Si

We propose and investigate the properties of a digital ferromagnetic heterostructure consisting of a delta-doped layer of Mn in Si, using ab initio electronic-structure methods. We find that (i) ferromagnetic order of the Mn layer is energetically favorable relative to antiferromagnetic, and (ii) the heterostructure is a two-dimensional half-metallic system. The metallic behavior is contributed by three majority-spin bands originating from hybridized Mn-d and nearest-neighbor Si-p states, and the corresponding carriers are responsible for the ferromagnetic order in the Mn layer. The minority-spin channel has a calculated semiconducting gap of 0.25 eV. The band lineup is found to be favorable for retaining the half-metal character to near the Curie temperature. This kind of heterostructure may be of special interest for integration into mature Si technologies for spintronic applications.

Antifouling properties of 10beta-formamidokalihinol-A and kalihinol A isolated from the marine sponge Acanthella cavernosa

Many soft-bodied sessile marine invertebrates such as sponges and soft corals defend themselves against fouling directly through the production of antifouling compounds, or indirectly through regulating the epibiotic microbes that affect larval settlement. In this study, 10beta-formamidokalihinol-A and kalihinol A were isolated and purified from the marine sponge Acanthella cavernosa (Dendy). The results indicated that both compounds inhibited the growth of bacteria isolated from the natural environment whereas kalihinol A suppressed larval settlement of a major fouling polychaete, Hydroides elegans with an EC50 of 0.5 microg ml(-1). Kalihinol A was incorporated in Phytagel that was exposed to the bacterial consortia in natural seawater for biofilm formation. Biofilms that developed on the Phytagel surfaces were analysed for bacterial abundance and bacterial species composition using a DNA fingerprinting technique, terminal restriction fragment length polymorphism (T-RFLP). The results showed that kalihinol A only slightly reduced bacterial abundance (t-test, p = 0.0497), but modified the bacterial species composition of the biofilms. Inhibition of H. elegans larval settlement was observed when biofilms developed under the influence of kalihinol A were exposed to larvae, suggesting that compounds like kalihinol A from the sponge A. cavernosa may change bacterial community composition on the sponge surface, which in turn, modulates larval settlement of fouling organisms.

Small-world properties emerge in highly compartmentalized networks with intermediate group sizes and numbers

Many recent studies have focused on two statistical properties observed in diverse real-world networks: the small-world property and compartmentalization [D. J. Watts and S. H. Strogatz, Nature 393, 440 (1998); M. Girvan and M. E. J. Newman, Proc. Natl. Acad. Sci. 99, 7821 (2002)]. Models that include group affiliations have been shown to produce networks with high clustering coefficients, a necessary condition for small-world properties [M. E. J. Newman, Phys. Rev. E, 68, 026121 (2003); M. E. J. Newman and J. Park, Phys. Rev. E 68, 036122 (2003)]. However, the consequences of varying the number and size of groups in a network are not well understood. In order to investigate the consequences of group organization, we examined sets of networks that varied simultaneously in the size and number of groups, while maintaining the same overall size and average degree. Here we show that the small-world property arises in maximally compartmentalized and clustered networks that occur in the intermediate region between few, very large groups and many, very small groups.

Interactions between a detrital resource pulse and a detritivore community

Detritivore communities influence the decomposition of detrital resources in virtually all natural systems. Conversely, detrital resources can also have considerable bottom-up effects on detritivore communities. While many investigations have examined detritivory and decomposition processes, few have considered interactions between detritivores and detritus as concurrent processes in the same system, or in the context of natural detrital pulses. In many systems, resource pulses contribute substantial detrital inputs to belowground systems. These detrital pulses may influence interactions between the detritivore community and detrital decomposition. I conducted field experiments to investigate interactions between detrital resource pulses of periodical cicada (Magicicada spp.) carcasses and scavenging detritivorous macroarthropods. Cicada litterfall pulses influenced several broad groups in the macroarthropod community, including relatively specialized necrophilous taxa and relatively generalized detritivores, omnivores and predators. Conversely, detritivore activity increased the rate of cicada carcass decomposition by 4,082% compared to caged control carcasses. These results suggest that interactions between pulses of cicada detritus and the detritivore community influence both the persistence of ephemeral detrital resources, and the distribution, abundance and behavior of detritivore populations.

Periodical Cicadas as Resource Pulses in North American Forests

Resource pulses are occasional events of ephemeral resource superabundance that occur in many ecosystems. Aboveground consumers in diverse communities often respond strongly to resource pulses, but few studies have investigated the belowground consequences of resource pulses in natural ecosystems. This study shows that resource pulses of 17-year periodical cicadas (Magicicada spp.) directly increase microbial biomass and nitrogen availability in forest soils, with indirect effects on growth and reproduction in forest plants. These findings suggest that pulses of periodical cicadas create "bottom-up cascades," resulting in strong and reciprocal links between the aboveground and belowground components of a North American forest ecosystem.

The ecology of individuals: incidence and implications of individual specialization

Most empirical and theoretical studies of resource use and population dynamics treat conspecific individuals as ecologically equivalent. This simplification is only justified if interindividual niche variation is rare, weak, or has a trivial effect on ecological processes. This article reviews the incidence, degree, causes, and implications of individual-level niche variation to challenge these simplifications. Evidence for individual specialization is available for 93 species distributed across a broad range of taxonomic groups. Although few studies have quantified the degree to which individuals are specialized relative to their population, between-individual variation can sometimes comprise the majority of the population's niche width. The degree of individual specialization varies widely among species and among populations, reflecting a diverse array of physiological, behavioral, and ecological mechanisms that can generate intrapopulation variation. Finally, individual specialization has potentially important ecological, evolutionary, and conservation implications. Theory suggests that niche variation facilitates frequency-dependent interactions that can profoundly affect the population's stability, the amount of intraspecific competition, fitness-function shapes, and the population's capacity to diversify and speciate rapidly. Our collection of case studies suggests that individual specialization is a widespread but underappreciated phenomenon that poses many important but unanswered questions.

Beta D305A mutant of tryptophan synthase shows strongly perturbed allosteric regulation and substrate specificity

Substrate channeling in the tryptophan synthase bienzyme is regulated by allosteric interactions. Allosteric signals are transmitted via a scaffolding of structural elements that includes a monovalent cation-binding site and salt-bridging interactions between the side chains of betaAsp 305, betaArg 141, betaLys 167, and alphaAsp 56 that appear to modulate the interconversion between open and closed conformations. betaAsp 305 also interacts with the hydroxyl group of the substrate L-Ser in some structures. One possible functional role for betaAsp 305 is to ensure the allosteric transmission that triggers the switching of alphabeta-dimeric units between open and closed conformations of low and high activity. This work shows that substitution of betaAsp 305 with Ala (betaD305A) decreases the affinity of the beta-site for the substrate L-Ser, destabilizes the enzyme-bound alpha-aminoacrylate, E(A-A), and quinonoid species, E(Q), and changes the nucleophile specificity of the beta-reaction. The altered specificity provides a biosynthetic route for new L-amino acids derived from substrate analogues. betaD305A also shows an increased rate of formation of pyruvate upon reaction with L-Ser relative to the wild-type enzyme. The formation of pyruvate is strongly inhibited by the binding of benzimidazole to E(A-A). Upon reaction with L-Ser and in the presence of the alpha-site substrate analogue, alpha-glycerol phosphate, the Na(+) form of betaD305A undergoes inactivation via reaction of nascent alpha-aminoacrylate with bound PLP. This work establishes important roles for betaAsp 305 both in the conformational change between open and closed states that takes place at the beta-site during the formation of the E(A-A) and in substrate binding and recognition.

First principles molecular dynamics of dense plasmas

Ab initio molecular dynamics calculations are performed for the equation of state of aluminum, spanning condensed matter and dense plasma regimes. Electronic exchange and correlation are included with either a zero- or finite-temperature local density approximation potential. Standard methods are extended to above the Fermi temperature by using final state pseudopotentials to describe thermally excited ion cores. The predicted Hugoniot equation of state agrees well with earlier plasma theories and with experiment for temperatures from 0 to 3 x 10(6) K.

An Outbreak of Typhoid Fever, Xing‐An County, People's Republic of China, 1999: Estimation of the Field Effectiveness of Vi Polysaccharide Typhoid Vaccine

To evaluate the effectiveness of Vi polysaccharide vaccine (Vi vaccine) in preventing typhoid fever, an analysis was done of an outbreak of typhoid fever among students attending a middle school in the People's Republic of China, where Vi vaccine is licensed for use. Vi vaccine effectiveness was analyzed by using Cox proportional hazards modeling to account for the time-dependent nature of vaccination and illness status during the outbreak. Among 1260 students who had been immunized before the outbreak, receipt of Vi vaccine was associated with 73% (95% confidence interval [CI], 32%-89%) protection. Among the additional 441 students immunized during the outbreak, receipt of Vi vaccine was associated with 71% (95% CI, -9% to 92%) protection. These results provide the first evidence about the effectiveness of Vi vaccine when deployed routinely in a typhoid-endemic area and support the use of Vi vaccine as a public health tool to control typhoid fever.

Investigation of allosteric linkages in the regulation of tryptophan synthase: the roles of salt bridges and monovalent cations probed by site-directed mutation, optical spectroscopy, and kinetics

The tryptophan synthase bienzyme complex is the most extensively documented example of substrate channeling in which the oligomeric unit has been described at near atomic resolution. Transfer of the common metabolite, indole, between the alpha- and the beta-sites occurs by diffusion along a 25-A-long interconnecting tunnel within each alphabeta-dimeric unit of the alpha(2)beta(2) oligomer. The control of metabolite transfer involves allosteric interactions that trigger the switching of alphabeta-dimeric units between open and closed conformations and between catalytic states of low and high activity. This allosteric signaling is triggered by covalent transformations at the beta-site and ligand binding to the alpha-site. The signals are transmitted between sites via a scaffolding of structural elements that includes a monovalent cation (MVC) binding site and salt bridging interactions of betaLys 167 with betaAsp 305 or alphaAsp 56. Through the combined strategies of site-directed mutations of these amino acid residues and cation substitutions at the MVC site, this work examines the interrelationship of the MVC site and the alternative salt bridges formed between Lys beta167 with Asp beta305 or Asp alpha56 to the regulation of channeling. These experiments show that both the binding of a MVC and the formation of the Lys beta167-Asp alpha56 salt bridge are important to the transmission of allosteric signals between the sites, whereas, the salt bridge between betaK167 and betaD305 appears to be only of minor significance to catalysis and allosteric regulation. The mechanistic implications of these findings both for substrate channeling and for catalysis are discussed.

Effectiveness of a multidisciplinary rehabilitation program in elderly patients with hip fractures

BACKGROUND AND PURPOSE

Hip fracture is a significant health challenge to the elderly, with a high risk of complications, long hospital stay, and functional deterioration. The purpose of this study was to evaluate the effectiveness of a multidisciplinary rehabilitation program (MRP) in older patients with hip fractures.

METHODS

A before-and-after quasi-experimental design was used. Data were collected at a large teaching hospital in Taipei. The first 105 consecutive patients admitted received conventional care (control group). The next 50 consecutive patients received physical therapy, nurse-supervised exercise, and discharge planning (intervention group). Subjects were assessed upon admission, on the fourth postoperative day, and on the discharge day. The 155 patients recruited met the following criteria: 60 years of age or older, and hospitalized to receive either closed reduction and internal fixation, or hip arthroplasty.

RESULTS

Compared with the control group, the intervention group had a shorter average hospital stay (9.9 vs 11.6 days, p = 0.01), earlier ambulation (5.7 vs 6.5 days postoperatively), and a lower rate of bowel incontinence (4.0% vs 23.8%) and pressure sores (14.0% vs 24.8%) during hospitalization. The intervention group experienced less decline in mobility (relative to pre-fracture status) than the control group. No significant difference was found in other outcome variables between the control and intervention groups.

CONCLUSIONS

The findings of this study indicate that an MRP involving physical therapy, nurse-supervised exercise, and discharge planning positively affects health outcomes in older patients with hip fractures.