基质栽培对国内主栽山药品种产量和品质的影响

为选择适合无土栽培的山药品种,利用灰色关联法对不同山药品种进行了基质栽培试验。结果表明,农大长山药1号对基质栽培比较适应,综合性状最优,汾阳山药次之,以下依次为平凉山药,蠡县麻山药,温县怀山药,定兴棒山药,太谷山药,北京自皮山药,农大短山药一号,济宁米山药,丰县水山药和安顺山药。农大长山药1号在基质栽培中表现突出,是无土栽培的理想品种。     

MoTlg2, a t-SNARE component is important for formation of the Spitzenkörper and polar deposition of chitin in Magnaporthe oryzae

T-SNAREs are a family of conserved proteins involved in intracellular transport of membrane-coated cargo among subcellular compartments. In this study, we identified a putative t-SNARE gene, MoTLG2, in Magnaporthe oryzae via insertion mutagenesis. Deletion of MoTLG2 resulted in slower vegetative growth and less conidiation relative to the wild-type strain, but the ΔMotlg2 null mutant was as virulent as the wild-type strain. MoTlg2 has 30% overall amino acid identity with Saccharomyces cerevisiae Tlg2, and rescued the defect of monensin de-sensitivity in the yeast strain where TLG2 had been deleted. More importantly, apical regions of the hyphae of the ΔMotlg2 null mutant were only weakly stained by FM4-64, which was reported as an excellent vesicle tracer, suggesting that the Spitzenkörper was not well formed in the ΔMotlg2 null mutant. In addition, more uneven lateral deposition of chitin was observed in the cell wall of vegetative hyphae of the ΔMotlg2 null mutant. Taken together, this study shows that the t-SNARE Tlg2 is important for both vegetative hyphal growth and conidiation, but dispensable for plant infection in filamentous fungi, and suggests that Tlg2 is important for formation of the Spitzenkörper and polar distribution of chitin.     

Are social embeddedness associated with food risk perception under media coverage?

Traceability system has received wide attention in solving food safety issues, via which food information could be tracked back to producer/farmers. Consumers need to obtain this information from producers or social networks, trust in the information,and consequently assess perceived risks, especially when food scandals are exposed to the media. In this study, we introduce the social embeddedness theory to understand how consumers' social activities affect their risk perceptions on traceable food. Specifically, we investigate how risk perceptions are predicted by the interpersonal relationships, organizational level and social-level relationships. Results show that the interpersonal relationships were associated with lower levels of risk perceptions, while organizational and social relationships impacted consumer's risk perceptions at middle and higher levels,respectively. Results also show that the "ripple effect" extended to effect of risk events with negative information, however,did not exist for the group exposed to positive information. Potential food safety implications have been proposed to identify for effective risk mitigation under media coverages.     

Serological survey of exposure to Erysipelothrix rhusiopathiae in poultryin New Zealand

Abstract

AIMS: To estimate the seroprevalence of antibodies to Erysipelothrix rhusiopathiae in chickens in New Zealand, and to estimate the effect of housing type, geographical location and age on seroprevalence.

METHODS: A cross-sectional serological survey of a convenience sample of 545 broiler, breeder, and layer chickens in 55 flocks was conducted in 2010–2011. Birds were aged 5–83 weeks; housing types were free-range, shed, caged, and unknown; and flocks were located in the Auckland, Manawatu, North Canterbury, Otago, Taranaki, Waikato, and Wairarapa regions of New Zealand. An ELISA was used to measure antibodies to E. rhusiopathiae. Samples with an optical density reading ≥1.50 were considered to be positive. Logistic regression analysis was used to model the effect of housing type, geographical location and flock age on the prevalence of samples positive for antibodies to E. rhusiopathiae.

RESULTS: The overall prevalence of samples with antibodies to E. rhusiopathiae was 39.8 (95% CI=35.68–44.06)% for the 545 samples, and 46/55 (84%) farms that were tested had at least one positive sample. Mean seroprevalence for types of housing was 44.2 (95% CI=37.79–50.70)% for free-range (n=240 birds), 23.7 (95% CI=17.83–30.38)% for shed (n=190), 73 (95% CI=56–86)% for caged (n=37) and 50 (95% CI=38–62)% for unknown (n=78). The disease was present in all seven geographical locations from which samples were obtained for this study. Seroprevalence increased with increasing age of birds (p<0.001); for birds ≤12 weeks of age it was 2 (95% CI=0.3–8)% (n=91), 13–24 weeks 29.1 (95% CI=23.34–35.46)% (n=230), 25–36 weeks 47 (95% CI=32–64)% (n=40), 37–48 weeks 75 (95% CI=51–91)% (n=20), >48 weeks 63.8 (95% CI=54.78–72.12)% (n=127). Neither housing type nor geographical location had a significant effect on the likelihood of samples being positive for antibodies to E. rhusiopathiae.

CONCLUSIONS: The results of this study suggest the prevalence of erysipelas under New Zealand field conditions may be higher than expected and that the disease is significantly associated with increasing age. Housing type and geographical location appear to be unrelated to seroprevalence.

CLINICAL RELEVANCE: Further study of the epidemiology of E. rhusiopathiae in chickens in New Zealand should be considered in order to minimise the extent of birds' exposure to the organism. These findings will assist in the design of further studies.     

Greenway service supply and public demand in Guangzhou city,China

Small-size green spaces contain convenient service capabilities for urban residents and satisfy the daily needs of citizens for high-quality ecological products. A greenway is a kind of linear green space, which can create a beautiful and livable environment in a high-density urban area. This study explored whether the services provided by the greenway can meet the daily needs of urban residents for green space in Guangzhou, a mega city in south China. Based on the Analytic Hierarchy Process (AHP) method and the entropy weight (EW) method, both the coupling coordination degree model and spatial autocorrelation analysis were adopted to quantify and determine the coordination degree of greenway service supply and public demand in Guangzhou. The results showed that the comprehensive score of the greenway service supply (GSS) subsystem and the public demand (PD) subsystem in Guangzhou was 0.3865 ± 0.08 and 0.3778 ± 0.03 (mean±s.e., n = 11), respectively. The GSS subsystem score was slightly higher than that of PD subsystem (P > 0.05), indicating that the two subsystems had no significant differences. The supply and demand subsystem of ten districts (excluding Conghua) in Guangzhou achieved different levels of coordination, and the average coupling coordination degree was 0.5885, suggesting that the districts were barely balanced at the city level. The Moran's I value was 0.580, indicating that the coupling coordination degree had significant positive global spatial autocorrelation and showed a spatial agglomeration effect. Furthermore, the local Moran’s I spatial autocorrelation showed that three districts (i.e., Yuexiu, Haizhu and Liwan) formed a high supply-high demand cluster and a spatial difference was detected when coupling the GSS and PD in Guangzhou. Therefore, we proposed the differentiated optimization strategies based on the results of the coupling coordination degree and the development status of each district and the entire city. This knowledge can better guide the subsequent construction and development of greenway in Guangzhou and may be useful for adjacent cities in Asia-Pacific region.     

Using social media data to understand the impact of the COVID-19 pandemic on urban green space use

Having access to and visiting urban green space (UGS) improves liveability and provides considerable benefits to residents. However, traditional methods of investigating UGS visitation, such as questionnaires and social surveys, are usually time- and resource-intensive, and frequently provide less transferable, site-specific outcomes. This study uses social media data (Twitter) to examine spatio-temporal changes in UGS use in London associated with COVID-19 related lockdowns. It compares georeferenced Tweets posted in a 3 month period from 23 March to 23 June for 3 years covering the first lockdown in the UK in 2020, with Tweets for the same period in 2019 and 2021. The results show that (1) the land-use type of Public Park and Garden was the most frequently visited type of UGS, which may be correlated with these UGS areas remaining opening during the lockdown period; (2) the usage of UGS decreased in central London and increased in other areas during lockdown, which may correlated with working from home restrictions; (3) activities were positively associated with Physical activities maybe as a result of allowing people to take a single daily exercise, and (4) people spent more time in UGS areas on weekdays than weekends compared to pre-lockdown. This is the first study to examine social media data over consistent time period before, during and after the lockdown in relation to UGS. The results show that the findings and method can inform policy makers in their management and planning of UGS, especially in a period of social crisis like the COVID-19 pandemic.     

A novel index for assessing perceived availability and public demand for urban green space: Application in a Mediterranean island

The objective benefits that humans derive from natural ecosystems and their enduring manifestation in urban green spaces (UGS) is well-know. Nevertheless, citizens’ preference, and perceived necessity of UGS is not always evident and therefore often not accounted for, especially in the context of urban planning decisions, where it could positively influence the effectiveness of greening strategies. This information is especially important in the Mediterranean islands, due to their unique character. Here we address these aspects, including the way they are affected by UGS perceived adequacy, accessibility, maintenance, distance, and other self-reported obstacles using a questionnaire completed by 703 residents of the Island of Crete, Greece. To integrate results, main covariates are compiled into the newly developed public UGS approval index. Survey results show that, 87.82 % of the participants consider public UGS highly necessary for their wellbeing, while only 69.22 % consider private UGS equally necessary. Nevertheless, private UGS were the most frequently visited green at 16.3 ± 0.7 days/month. Public UGS is considered more necessary for female respondents, under 35 years, living in an apartment in the city. However, it emerged that despite the significantly higher need for public UGS in the urban centers of the island, residents consider UGS inadequate and often inaccessible for people with mobility problems. Integration of the results in the new approval index, shows that citizens of Crete, are on average neutral or disapprove of local public UGS. The outcomes can be used for targeted interventions at existing and strategic planning in new UGS.     

橡胶树白粉病菌分生孢子在不同介质的萌发过程及其内容物的变化

 本研究采用不同的染色方法和显微技术观察橡胶树白粉病菌(Oidium heveae)分生孢子的超微结构,分生孢子在不同介质表面及不同介质溶液中的萌发情况,以及孢子萌发过程中孢内主要物质的变化,以明确O. heveae分生孢子在不同介质萌发的形态变化及萌发所需能量来源。结果表明：O. heveae 分生孢子表面具有较浅的花纹结构,呈椭圆形或者卵圆形,大小为26.1~45.1μm×13.5~21.9μm。O. heveae 分生孢子在亲水和疏水介质上均能萌发产生芽管和附着胞,在葡萄糖水中的萌发率略高于清水中,但萌发率无显著性差异 (P>0.05),芽管和附着胞形成与形态无明显差别。分生孢子萌发过程中,几个液泡会融合形成一个,最终消散而呈不明显可见的泡囊结构。孢子内的糖原、脂质及分裂后的核仁等可通过芽管向附着胞输送,表明O. heveae 分生孢子萌发所需能量物质主要来源于自身能量贮备。     

Factors that enhance or hinder social cohesion in urban greenspaces: A literature review

Urban greenspaces--including city parks, forests, and gardens--can provide many benefits that impact human wellbeing. One such aspect of wellbeing is social cohesion, which is broadly defined as the combined reasons to stay in a particular community. Although there is an increase in studies connecting human wellbeing, social cohesion, and urban greenspace, there is limited synthesis of the three concepts. The purpose of this paper is to review how social cohesion has been used, defined, and measured in the scholarly literature. In addition, we assess the factors that hinder or enhance social cohesion in urban greenspace and opportunities for future research. We conducted a systematic literature review using the PRISMA procedures. After doing a search with keywords, we read the abstracts of 1129 articles and selected 113 that met our inclusion criteria for final in-depth analysis. We provide an overview and conceptual diagram of the factors that enhance or hinder social cohesion in urban greenspaces. Although all of the analyzed articles included social cohesion as a variable or topic of interest, only 17 of those articles clearly defined and measured social cohesion. The most impactful ways to enhance social cohesion include reducing crime, improving maintenance, and having physical space and amenities for social gatherings that cater to various demographics. Likewise, studies suggest that the perceptions of safety, level of maintenance, accessibility, and efforts to be inclusive of diverse users including cultural activities and community engagement spaces were important to social cohesion. Overall, more research is needed to better understand social cohesion and urban greenspace in developing countries, and more in-depth analysis from the perspective of diverse urban residents who use these greenspaces. The results of this study have implications for designing and managing urban greenspaces to enhance social cohesion, inclusion, and overall human wellbeing.