混合培养对固氮菌和纤维素分解菌生长及固氮的影响

对筛选的自生固氮菌和纤维素分解菌进行混合培养 ,研究了菌数与菌液含氮量的变化情况 ,并与其单独培养进行了比较。实验证明 :在混合培养条件下 ,两种菌能相互利用、相互促进 ,混合培养液的菌数增加 ,固氮菌的固氮能力提高。这两种菌可混合培养制成混合菌剂。。     

生态系统生态学研究的关键问题及趋势——从“整体论与还原论的争论”看

在生态学领域中,存在着生态系统整体论与还原论的争论。Tansley A.G.提出,生态系统是"准有机体"。Odum兄弟提出的"生态系统能量说"被广泛接受,但也受到质疑,称其为"还原论者的整体论"。基于对上述质疑的回应以及对生态系统整体论的追求,Patten B.C.等提出"生态网络理论",运用"网络‘环境子’分析"方法,试图从物理层面分析解决生物层面的"涌现性"问题。不过,这一理论也受到批判,认为其在探究符号化的现象对生态系统的动态影响时,陷入了还原论困境。Jrgensen S.E.等更进一步,提出"系统论"的生态系统生态学,试图从系统科学的角度研究生态系统的"物质-能量-信息-网络"系统。这一理论受到生态学界高度重视,但是也存在着在具体研究过程中如何平衡能量视角和生物地球化学视角的问题。由上述争论可见,生态系统生态学研究的趋势是从"物质实体"到"能量流动",再到"网络信息",最后到"开放系统"层层递进。目前面临的关键问题是:如何在更好地定义生态系统整体性的基础上,采取相应的能够体现生态系统整体性的方法,去获得更多、更好的生态系统整体性的认识。     

Caiman latirostris (broad-snouted caiman) as a sentinel organism for genotoxic monitoring: Basal values determination of micronucleus and comet assay

Caiman latirostris is one of the two crocodilian species that inhabit Argentina. In this country, as a consequence of agricultural frontiers expansion during the last years, many areas of the geographic distribution of the broad snouted caiman overlap with regions of intensive agricultural activity. Contaminants released to the environment may induce genetic alterations in wildlife, which could lead to mutations and/or carcinogenesis. Up to the moment, no studies had been made concerning the possibbility to apply biomarkers of genotoxic evaluation in C. latirostris.The aim of this study was to adapt two widely used genotoxic techniques, the comet assay and the micronucleus test, for their application in C. latirostris and to determine the baseline values in this species, in order to establish its suitability as a sentinel organism for future genotoxic monitoring of environmental pollutants.A total of 41 juvenile caimans of 4 months old (FMO) and 10 months old (TMO) were used. Genotoxic techniques were applied on peripheral blood erythrocytes introducing the necessary modifications required by the material, which are presented here.Our results show that baseline values of DNA damage are quite stable among juvenile caimans (MN: FMO animals 0.87 ± 0.74 and TMO animals 1.04 ± 0.92; DI: FMO animals 103.40 ± 3.36 and TMO animals 120.08 ± 11.33), being independent of the nest of origin, sex and size of the animals and confirm the potential value of both short term tests as accurate screening tools for the evaluation of genotoxic agents in C. latirostris. This is the first reference to the application of genotoxic techniques on C. latirostris and the second in crocodilians.Data provided here will be useful for future studies involving the biomonitoring of natural regions where C. latirostris occurs, employing this species as a sentinel organism for genotoxic assessment of environmental pollutants.     

Height development of men and women from China,South Korea,and Taiwan during the rapid economic transformation period of the 1960s–1980s

We study height trends among Chinese, South Korean, and Taiwanese groups during the rapid economic growth period of the 1960s to the 1980s. Heights rose strongly as income grew. Did rapid income growth also cause a decline in gender inequality? Or did it rise because the gains were unevenly distributed? Gender inequality is particularly interesting given the traditionally strong son preference in the region. For mainland China, we find that gender inequality was relatively modest in the pre-reform period (before the 1980s). Especially in comparison to the early 20th century, female heights grew faster than male heights. In contrast, the 1980s transition period to an economic system with market elements was characterized by increasing gender inequality in China. This was the case to an even greater extent in South Korea, where gender dimorphism noticeably increased during the 1980s, paralleling a similar increase in sex-selective abortions. Moreover, we also study other inequality patterns in the three countries, focusing on socioeconomic, regional, and educational differences between groups.     

A simple boronic acid-based fluorescent probe for selective detection of hydrogen peroxide in solutions and living cells

An approach of high sensitivity and selectivity for hydrogen peroxide (H₂O₂) detection is highly demanded due to its important roles in regulating diverse biological process. In this work, we introduced an easily synthesized fluorescent “turn off” probe, BNBD. It is designed based on the core structure of 4-chloro-7-nitrobenzofurazan as a fluorophore and incorporated with a specific H₂O₂-reactive group, aryl boronate, for sensitive and selective detection of H₂O₂. We demonstrated its selectivity by incubating the probe with other types of ROS, and measured the limit of detection of BNBD as 1.8 nM. BNBD is also conducive to H₂O₂ detection at physiological conditions. We thus applied it to detect both exogenous and endogenous changes of H₂O₂ in living cells by confocal microscopy, supporting its future applications to selectively monitor H₂O₂ levels and identify H₂O₂-related physiological or pathological responses from live cells or tissues in the near future.     

Assembly and RNA‐free annotation of highly heterozygous genomes: The case of the thick‐billed murre (Uria lomvia)

Thanks to a dramatic reduction in sequencing costs followed by a rapid development of bioinformatics tools, genome assembly and annotation have become accessible to many researchers in recent years. Among tetrapods, birds have genomes that display many features that facilitate their assembly and annotation, such as small genome size, low number of repeats and highly conserved genomic structure. However, we found that high genomic heterozygosity could have a great impact on the quality of the genome assembly of the thick‐billed murre (Uria lomvia), an arctic colonial seabird. In this study, we tested the performance of three genome assemblers, ray /sscape , soapdenovo 2 and platanus , in assembling the highly heterozygous genome of the thick‐billed murre. Our results show that platanus , an assembler specifically designed for heterozygous genomes, outperforms the other two approaches and produces a highly contiguous (N50 = 15.8 Mb) and complete genome assembly (93% presence of genes from the Benchmarking Universal Single Copy Ortholog [BUSCO] gene set). Additionally, we annotated the thick‐billed murre genome using a homology‐based approach that takes advantage of the genomic resources available for birds and other taxa. Our study will be useful for those researchers who are approaching assembly and annotation of highly heterozygous genomes, or genomes of species of conservation concern, and/or who have limited financial resources.     

猿人洞的溶洞演化和堆积旋回与北京猿人生活环境

猿人洞的溶洞演化过程按岩溶洞穴发生发展规律可划分为６个阶段．在洞穴发育的填充过程中,依据堆积物的成因类型,猿人洞中的中更新世洞穴堆积层可分为７个堆积旋回．每个堆积旋回可与年代相当的黄土堆积旋回和深海气候旋回—一对应．堆积旋回所显示的气候和洞穴环境变化均与北京猿人生活环境及其旧石器文化的发展有着密切的关系．     

Application of unicellular algae Chlorella vulgaris for the mass-culture of marine rotifer Brachionus

Condensed suspension of Chlorellavulgaris was used for the food of the rotifer Brachionus plicatilis and B. rotundiformis inplace of Nannochloropsis oculata. Thisreport describes the characteristics of C. vulgaris as arotifer food in comparison with N. oculata and thepresent status of this field.The cell components of C. vulgarissuch as protein content, amino acids, minerals andvitamins are generally similar to those of N. oculata. However, the taxonomic status of thesealgal species are different. Based on thesimilarity of cell components, the dietary value ofC. vulgaris is equal in value to that of N. oculata for rotifer growth. Dietary value ofC. vulgaris can be improved by addition ofvitamin B₁₂. This improved C. vulgaris is currently widely used as an indispensable food organism for rotifer culture. Recent investigationshave shown that the use of the condensed suspensionof C. vulgaris makes it possible tosignificantly increase the rotifer density atharvest. Application of condensed C. vulgaris has made rotifer culture quite easy because theculture of N. oculata is no longer required,and intensive rotifer production in aquaculture cannow be realized.