“三生”空间视角下土地利用转型的生态环境效应及驱动力——以甘肃省为例

中国社会经济快速转型背景下土地利用变化所引发的环境问题被广泛关注。以土地利用现状遥感监测数据和统计资料为数据源,借助ArcGIS和SIMCA-P软件平台,基于"三生"空间视角,通过生态环境质量指数测度了1980—2018年甘肃省土地利用转型的生态环境效应,并运用偏最小二乘法揭示生态环境质量演变的驱动机制。研究发现:(1)"三生"空间结构演化和地域分异显著。生产、生活空间集中分布于河西走廊、陇中和陇东黄土高原并呈扩张态势;生态空间主要分布于陇南山地、甘南高原、祁连山地和河西走廊以北地带且整体呈缩减趋势;生产、生活空间的增长源于对生态空间的侵占。(2)生态环境质量改善和恶化趋势并存,整体上经历了先下降后上升的"U"形演化过程;空间上呈"东南高-西北低"的分布特征,空间格局演化具有明显的集聚性。(3)生态建设、科技进步等对生态环境改善具有明显的促进作用;而人口增加、社会消费水平提升在一定程度上加剧了生态环境压力;对外贸易对生态环境的影响具有双面性。     

上海城市近自然森林的重建动态

近自然森林作为城市植被恢复的重要模式,已在我国多地开展了实践,并衍生了新的造林模式。为评估不同近自然森林建设模式的群落恢复进程,本研究以上海城市裸地上重建的近自然森林为对象,通过长期监测两处分别应用原"宫胁法"与新"异龄复层落叶—常绿混交林"种植模式的近自然森林重建过程,从物种组成、垂直结构、生活型组成和目标恢复物种4个方面解析恢复动态。结果表明:两种造林模式恢复的近自然森林,随恢复进程其物种组成逐渐趋同,在十多年内已形成了落叶—常绿垂直混交结构;"异龄复层落叶—常绿混交林"造林模式可更好地促进常绿阔叶树种的恢复,尤其是常绿建群种红楠与小叶青冈。本研究证实了近自然森林恢复技术可以缩短亚热森林群落向演替后期发展的时间,以及新造林模式的有效性,为近自然森林技术的应用与实施提供了科学依据。     

Isolation and analysis of DNA markers specific to human chromosome 15.

Chromosome-specific DNA markers provide a powerful approach for studying complex problems in human genetics and offer an opportunity to begin understanding the human genome at the molecular level. The approach described here for isolating and characterizing DNA markers specific to human chromosome 15 involved construction of a partial chromosome-15 phage library from a human/Chinese hamster cell hybrid with a single human chromosome 15. Restriction fragments that identified unique- and low-copy loci on chromosome 15 were isolated from the phage inserts. These fragments were regionally mapped to the chromosome by three methods, including Southern analysis with a mapping panel of cell hybrids, in situ hybridization to metaphase chromosomes, and quantitative hybridization or dosage analysis. A total of 42 restriction fragments of unique- and low-copy sequences were identified in 14 phage. The majority of the fragments that have been characterized so far exhibited the hybridization pattern of a unique locus on chromosome 15. Regional mapping assigned these markers to specific locations on chromosome 15, including q24-25, q21-23, q13-14, q11-12, and q11. RFLP analysis revealed that several markers displayed polymorphisms at frequencies useful for genetic linkage analysis. The markers mapped to the proximal long arm of chromosome 15 are particularly valuable for the molecular analysis of Prader-Willi syndrome, which maps to this region. Polymorphic markers in this region may also be useful for definitively establishing linkage with one form of dyslexia. DNA probes in this chromosomal region should facilitate molecular structural analysis for elucidation of the nature of instability in this region, which is frequently associated with chromosomal aberrations.     

Comparison Between Etest and Broth Microdilution Methods for Testing Itraconazole-Resistant <Emphasis Type="Italic">Aspergillus fumigatus</Emphasis> Susceptibility to Antifungal Combinations

The checkerboard broth microdilution assay (BMD) is the most frequently used method for the in vitro evaluation of drug combinations. However, its use to evaluate the effect of antifungal drugs on filamentous fungi is sometimes associated with endpoint-reading difficulties, and different degrees of interaction are assigned to the same drug combination. We evaluated combinations of the azoles, itraconazole, posaconazole, and voriconazole, with the echinocandins, anidulafungin, caspofungin, and micafungin, against 15 itraconazole-resistant Aspergillus fumigatus clinical strains via the checkerboard BMD and Etest assay. Readings after 24 and 48 h, considering the two reading endpoints, the minimum inhibitory concentration (MIC) and minimum effective concentration (MEC), were performed for both methods. Our results showed that the correlation coefficients between the BMD and Etest methods were quite diverse to the drug combinations tested. The highest correlation coefficients of the Etest with the BMD assays (MEC and MIC reading) were the Etest-MIC reading at 24 h and the Etest-MEC reading at 48 h. Improvements in experimental conditions may increase the correlation between the two methods and ensure that Etest assay can be safely used in the evaluation of antifungal combinations against Aspergillus species.     

Indoor and outdoor winter activity of Culicoides biting midges,vectors of bluetongue virus,in Italy

Indoor and outdoor winter activity of Culicoides spp. (Diptera: Ceratopogonidae) in central Italy was investigated in order to evaluate whether indoor activity might account for the overwintering of bluetongue virus, as has been hypothesized by some authors. Weekly Culicoides collections were performed at three farms over three consecutive winter seasons. At each farm, two black‐light traps were operated simultaneously, indoors and outdoors. Culicoides were identified using both morphological and molecular means. The Culicoides obsoletus group accounted for 98.2% of sampled specimens. Within this group, C. obsoletus s.s. accounted for 56.8% and Culicoides scoticus for 43.2% of samples. Nulliparous, parous and engorged females were caught throughout the entire winter, both indoors and outdoors. At times, indoor catch sizes outnumbered outdoor collections. A significant inverse correlation was found between minimum temperature and the proportion of indoor Culicoides of the total midge catch, thus indicating that lower outdoor temperatures drive Culicoides midges indoors. High rates of engorged females were recorded indoors, possibly as the result of the propensity of C. obsoletus females to feed indoors. Higher proportions of parous females were found in indoor than in outdoor catches, indicating higher survival rates indoors and, consequently, higher vectorial capacities of midges sheltering indoors compared with those remaining outdoors.     

Short-Term In Vitro Culture and Molecular Analysis of the Microsporidian, Enterocytozoon bieneusi

ABSTRACT. The microsporidium, Enterocytozoon bieneusi , causes a severe, debilitating, chronic diarrhea in patients with the acquired immunodeficiency syndrome. Specific diagnosis of intestinal microsporidiosis, especially due to Enterocytozoon , is difficult and there is no known therapy that can completely eradicate this parasite. Preliminary studies indicate that a short term (about 6 months) in vitro culture of this parasite yielding low numbers of spores, may be established by inoculating human lung fibroblasts and/or monkey kidney cell cultures with duodenal aspirates and or biopsy from infected patients. The cultures may subsequently be used for the isolation and molecular analysis of parasite DNA.     

Gram-Chromotrope: a New Technique that Enhances Detection of Microsporidial Spores in Clinical Samples

We have developed a new staining procedure that combines the traditional Gram staining for bacteria and the Weber's chromotrope staining method, the standard technique for the detection of microsporidia spores in clinical Specimens. This “Gram-chromotrope” staining technique enhances the staining characteristics of microsporidia spores and facilitates the easy detection and differentiation of spores from other microorganisms that are found in clinical specimens, especially stool samples. This new technique is fast, reliable, and simple to perform, and can be easily adapted for use in clinical laboratories.     

Hierarchical genetic structure and gene flow in three sympatric species of Amazonian rodents

The population genetic structure of three species of Amazonian rodents ( Oligoryzomys microtis, Oryzomys capito , and Mesomys hispidus ) is examined for mtDNA sequence haplotypes of the cytochrome b gene by hierarchical analysis of variance and gene flow estimates based on fixation indices ( N _ST) and coalescence methods. Species samples are from the same localities along 1000 km of the Rio Juruá in western Amazonian Brazil, but each species differs in important life history traits such as population size and reproductive rate. Average haplotype differentiation, hierarchical haplotype apportionment, and gene flow estimates are contrasted in discussing the current and past population structure. Two species exhibit isolation by distance patterns wherein gene flow is largely limited to geographically adjacent localities. Mesomys exhibits this pattern throughout its range along the river. More than 75% of haplotype variation is apportioned among localities and regions, and estimates of Nm for pair-wise comparisons are nearly always less than 1. Oligoryzomys shows weak isolation by distance, but only over the largest geographical distances. Nm values for this species are nearly always above 1 and most (about 80%) of haplotype variation is contained within local populations. In contrast, Oryzomys exhibits no genetic structure throughout its entire distribution; Nm values average 17 and nearly 90% of the total haplotype variance is contained within local populations. Although gene flow estimates are high, the pattern of Nm as a function of geographical distance suggests that this species experienced a more recent invasion of the region and is still in genetic disequilibrium under its current demographic conditions.