Nitrogen isotopic composition of leached nitrate and soil organic matter as an indicator of denitrification in a sloping drained agricultural plot and adjacent uncultivated riparian buffer strips

In the small, agricultural, artificially drained Orgeval watershed δ¹⁵N values of leached nitrates and soil organic nitrogen were found to be significantly higher than the primary nitrogen (N) sources from which they are derived, namely, synthetic fertilizers, atmospheric deposition, and symbiotic or nonsymbiotic N₂ fixation (all with δ¹⁵N close to zero). In vertical soil profiles, the δ¹⁵N of organic N increased with depth, reaching higher values (up to 8‰) particularly at stations that were frequently waterlogged as judged from ochre iron traces, such as downhill field sites or in riparian buffer strips. Nitrification, volatilization, and denitrification are the main fractionating processes able to modify the isotopic composition of soil N. Using a newly designed algorithm for calculating the equilibrium isotopic composition of all soil N species, resulting from the average annual balance of their transformations, we show that the observed trends can be explained by the action of denitrification. We suggest that the isotopic composition of soil organic N can be used as a semiquantitative indicator of the intensity of denitrification integrated over century-long periods.     

Mate choice of an endogeic earthworm revealed by microsatellite markers

Endogeic earthworms are difficult study subjects due to the cryptic medium in which they live; thus, only the behaviour of epigeic and anecic earthworms has been studied before. We used microsatellite markers as a tool to elucidate the mate choice processes of Hormogaster elisae, an endogeic earthworm. It was shown to normally mate with two partners, preferably of the same size that are found in close proximity thereby eliminating the need for long-distance dispersion, which could explain the previously observed high genetic differentiation between populations. The genetic analyses of the sperm within each of its four spermathecae showed a uniform distribution with no signs of differential storage of sperm from different partners.     

The fat that matters: Soil food web analysis using fatty acids and their carbon stable isotope signature

Chemical taxonomy based upon the composition of lipids is widely applied to investigate microbial communities and fatty acids have recently been employed to connect soil microbial and faunal food webs as well as to elucidate functional groups at higher trophic levels. The additional use of compound-specific isotopic analysis of ¹³C/¹²C ratios in fatty acids allows assessing specific trophic links and belowground carbon fluxes. In this review systematic patterns and processes underlying variations in the composition of fatty acids and their ¹³C/¹²C ratio are described. The emphasis is on biomarker fatty acids, their incorporation and modification, effects of pool size, and analytical methods. Further development of the application of fatty acid profiling to soil ecology should include both advances in experimental research and growth of theory. Accordingly, areas in which future experimentation can lead to progress in soil food web analysis are identified. Overall, combining fatty acid biomarker and their isotopic ratios will allow detailed insight into belowground trophic interactions.     

Immunohistochemical characterization of canine prostatic carcinoma and correlation with castration status and castration time

The purpose of this study was to characterize canine prostate cancer using immunohistochemical staining specific for acinar and urothelial/ductal tissue and correlate these results with the dogs' castration status/castration time. Seventy dogs with prostate cancer were included, 71% were castrated and 29% were intact. Compared with an age‐matched control population, castrated dogs were at increased risk of prostate cancer, odds ratio 3.9. Immunohistochemical staining was performed on 58 cases. Forty‐six of the 58 stained positive for cytokeratin 7 (CK 7) (ductal/urothelial origin) and one of the 58 stained positive for prostate‐specific antigen. Dogs with CK 7‐positive tumours were younger when castrated than dogs with CK 7‐negative tumours, 2 versus 7 years (P = 0.03); dogs castrated at ≤2 years of age were more likely to be CK 7‐positive (P = 0.009). These results show that most canine prostatic carcinomas are of ductal/urothelial, androgen‐independent origin. This is consistent with the epidemiological findings, showing increased risk in castrated dogs. Canine prostate cancer may, therefore, not be a realistic model for the human disease.     

Generalized marker regression and interval QTL mapping methods for binary traits in half-sib family designs

A Generalized Marker Regression Mapping (GMR) approach was developed for mapping Quantitative Trait Loci (QTL) affecting binary polygenic traits in a single-family half-sib design. The GMR is based on threshold-liability model theory and regression of offspring phenotype on expected marker genotypes at flanking marker loci. Using simulation, statistical power and bias of QTL mapping for binary traits by GMR was compared with full QTL interval mapping based on a threshold model (GIM) and with a linear marker regression mapping method (LMR). Empirical significance threshold values, power and estimates of QTL location and effect were identical for GIM and GMR when QTL mapping was restricted to within the marker interval. These results show that the theory of the marker regression method for QTL mapping is also applicable to binary traits and possibly for traits with other non-normal distributions. The linear and threshold models based on marker regression (LMR and GMR) also resulted in similar estimates and power for large progeny group sizes, indicating that LMR can be used for binary data for balanced designs with large families, as this method is computationally simpler than GMR. GMR may have a greater potential than LMR for QTL mapping for binary traits in complex situations such as QTL mapping with complex pedigrees, random models and models with interactions.     

一种新型公路划线车的专用喷涂系统

简要介绍了一种新型公路划线车专用喷涂系统的设计特点和使用功能。     

家鹑与野生日本鸣鹑群体微卫星DNA标记的遗传学分析

选择10个微卫星标记位点，合成引物对微山湖野生日本鸣鹑和家鹌鹑各40只进行PCR扩增，变性聚丙烯酰胺凝胶电泳检测分型，并对其品种内和品种间的遗传变异进行群体遗传学分析，从分子水平上揭示这两个鹌鹁群体的遗传结构关系、亲缘关系和遗传分化程度，为鹌鹑的遗传资源研究提供新资料。     

分子标记及其在云南稻种核心种质中的应用

本文总结了分子生物学发展的各类分子标记及其在核心种质中的应用。     

Similarities and differences between Amaranthus species and cultivars and estimation of outcrossing rate on the basis of electrophoretic separations of urea-soluble seed proteins

Wheat-rye translocation line (2BS/2RL) has been developed for resistance to biotype L of Hessian fly and agronomically useful traits. AFLP analysis using 64 primer pairs was conducted in order to identify 2RL-specific polymorphisms between “Coker 797” (non-2RL), near-isogenic line (NIL) carrying 2RL, and “Hamlet”. Nine primer combinations identified twelve reproducible polymorphic fragments in the NIL carrying 2RL. These twelve fragments were cloned and sequenced with an aim towards converting AFLP markers into sequence tagged sites (STS). A comparison of the 12 sequences with non-redundant accessions in the NCBI database using the BLAST search option indicated that one fragment of approximately 200 bp in length (amplified using primer combination E+AAC / M+CTA) was highly homologous with the rye-specific repetitive sequence R173-1 and Wis-2-lA, a retrotransposon-like element in wheat. Two STS primers (SJ07 and SJ09) out of twelve STS primer sets enabled the detection of polymorphisms between Coker 797 and NIL carrying 2RL. In order to verify whether the polymorphism detected by primers SJ07 and SJ09 was in fact the result of the presence of 2RL, additional plant material was examined. Amplified products of about 260 bp fragment with the SJ07 primer set were generated in rye cvs.“Chilbohomil” and “Jochunhomil”, triticale experimental line Suwon 15, and wheat experimental line K-14 (1AL/1RS & 2BS/2RL), as well as NIL carrying 2RL and Hamlet, but not in Coker 797 (non-2RL), “Keumgangmil” (non-translocation wheat), KS92WGRC17 (PI592729 /;/ 6BS/6BL-6RL), KS92WGRC19 (P1592731 /;/ 4BS/4BL-6RL), “TAM200” (1AL/1RS), and “Siouxland” (1BL/1RS). Our data suggest that primer set SJ07 amplifies a “2RL-specific” fragment of diagnostic value. This revised version was published online in August 2006 with corrections to the Cover Date.     

Intraspecific olive diversity assessed with AFLP

Amplified fragment length polymorphism (AFLP) was used to study diversity within and among Spanish olive varieties. A high degree of diversity was found among the varieties present in each growing region. Olive oil production and quality relies on appropriate cultivar selection as well as good orchard management. Production based only on a few superior cultivars would result in improved yield, oil quality, and production management. Amplified fragment length polymorphism were evaluated as a tool to identify the intraspecific and intravarietal diversity of olive. Amplified fragment length polymorphism analysis of 38 accessions belonging to 10 cultivars using six primer combinations produced 106 polymorphic bands. Results were analyzed for similarity among accessions via unweighted pair‐group means cluster analysis, resulting in 10 clusters corresponding to named variety designations. Similarity among varieties ranged from 0.60 to 0.72. Diversity within varieties was identified. Similarity within named varieties (accessions with the same varietal name) ranged from 0.75 to 0.96. Differences in several markers were found among 34 accessions. Intravarietal diversity was shown to exist within the Spanish olive varieties grown in the region surrounding Valencia.