Aphelenchoides hylurgi as a Carrier of White, Hypovirulent Cryphonectria parasitica and its Possible Role in Hypovirulence Spread on Blight-Controlled American Chestnut Trees

Individual nematodes were isolated from American chestnut blight-controlled cankers to determine if they were carriers of biocontrol (hypovirulent) isolates of the chestnut blight fungus, Cryphonectria parasitica. These hypovirulent isolates have a white fungal colony phenotype due to infection by the virus CHV1. Of 1,620 individual Aphelenchoides hylurgi isolated, 29.4% carried propagules of the blight fungus and 8.2% of these yielded white hypovirulent isolates. In attraction and movement tests in Petri plates, A. hylurgi moved 2 cm over 24 hr to mycelial discs of white hypovirulent C. parasitica and pigmented C. parasitica strains in nearly equal numbers. After 2 days of nematode movement to fungal colonies on agar in Petri plates and 21 days of nematode growth, large numbers of A. hylurgi were extracted from both white hypovirulent and pigmented C. parasitica strain colonies. Lower numbers of A. hylurgi were extracted from excised young American chestnut blight cankers that were inoculated with A. hylurgi and incubated for 22 days. A. hylurgi inoculated on the surface of an excised American chestnut canker moved within 24 hr to the small, spore-bearing C. parasitica reproductive structures (stromata) on the canker surface. The results indicate that A. hylurgi may play a role in the spread of hypovirulence on American chestnut trees.     

Characterization of Bacillus thuringiensis isolates from Argentina that are potentially useful in insect pest control

In order to find novel strains of Bacillus thuringiensis that are toxic to some of the major pests that impact economically important crops in Argentina, we initiated a search for B. thuringiensis isolates native to Argentina. We succeeded in assembling a collection of 41 isolates, some of which show a high potential to be used in biological control programs against lepidopteran and coleopteran pests. About 90% of the strains showed toxicity against Spodoptera frugiperda and Anticarsia gemmatalis, two important lepidopteran pests in Argentina. It is noteworthy that only one of these strains contained a cry1-type gene, while another isolate showed a dual toxicity against the lepidopteran and coleopteran insects assayed. Genetic characterization of the strains suggests that the collection likely harbors novel Cry proteins that may be of potential use in biological insect pest control.     

Discrepancies between the phenotypic and genotypic characterization of Lactococcus lactis cheese isolates

AIMS: The use of randomly amplified polymorphic DNA (RAPD)-PCR fingerprinting and plasmid profiles to determine at the strain level, the similarity of Lactococcus lactis isolates obtained during sampling of traditional cheeses and to verify its correspondence to the selected phenotypic characteristics. METHODS AND RESULTS: A total of 45 L. lactis isolates were genotypically analysed by RAPD-PCR fingerprinting and plasmid patterns. Phenotypic traits used to compare strains were proteolytic, acidifying, aminotransferase (aromatic and branched chain aminotransferase) and alpha-ketoisovalerate decarboxylase (Kivd) activities. The results show that 23 isolates could be grouped in clusters that exhibited 100% identity in both their RAPD and plasmid patterns, indicating the probable isolation of dominant strains during the cheese sampling process. However, there were phenotypic differences between isolates within the same cluster that included the loss of relevant technological properties such as proteinase activity and acidifying capacity or high variation in their amino acid converting enzyme activities. Likewise, the analysis of a specific attribute, Kivd activity, indicated that 7 of 15 isolates showed no detectable activity despite the presence of the encoding (kivd) gene. CONCLUSION: Phenotypic differences found between genotypically similar strains of L. lactis strains could be linked to differences in enzymatic expression. SIGNIFICANCE AND IMPACT OF THE STUDY: Phenotypic analysis of L. lactis isolates should be considered when selecting strains with new cheese flavour forming capabilities.     

Wild mouse open field behavior is embedded within the multidimensional data space spanned by laboratory inbred strains

The vast majority of studies on mouse behavior are performed on laboratory mouse strains (Mus laboratorius), while studies of wild-mouse behavior are relatively rare. An interesting question is the relationship between the phenotypes of M. laboratorius and the phenotypes of their wild ancestors. It is commonly believed, often in the absence of hard evidence, that the behavior of wild mice exceeds by far, in terms of repertoire richness, magnitude of variables and variability of behavioral measures, the behavior of the classical inbred strains. Having phenotyped the open field behavior (OF) of eight of the commonly used laboratory inbred strains, two wild-derived strains and a group of first-generation-in-captivity local wild mice (Mus musculus domesticus), we show that contrary to common belief, wild-mouse OF behavior is moderate, both in terms of end-point values and in terms of their variability, being embedded within the multidimensional data space spanned by laboratory inbred strains. The implication could be that whereas natural selection favors moderate locomotor behavior in wild mice, the inbreeding process tends to generate in mice, in some of the features, extreme and more variable behavior.     

Independent quantitative trait loci influence ventral and dorsal hippocampal volume in recombinant inbred strains of mice

Anatomical and functional studies support segregation of the hippocampus into ventral and dorsal components along its septotemporal axis. However, it is unknown whether the development of these two components of the hippocampus is influenced by common or separate genetic factors. In this study, we used recombinant inbred strains of mice to determine whether the same or different quantitative trait loci (QTL) influence ventral and dorsal hippocampal volume. Using two sets of strains of recombinant inbred mice (BXD and AXB/BXA), we identified separate QTLs for ventral and dorsal hippocampal volume. In BXD mice, suggestive QTLs for ventral hippocampus were identified on chromosomes 2, 8 and 13, and a significant QTL for dorsal hippocampal volume was identified on chromosome 15. There was also a suggestive QTL for dorsal hippocampal volume on chromosome 13. In AXB/BXA mice, there were no significant or suggestive QTLs for ventral hippocampal volume, but a significant QTL for dorsal hippocampus was identified on chromosome 5. These findings suggest that the development of the ventral and dorsal components of the hippocampus is influenced by separate genetic loci.     

Construction and characterization of centromeric, episomal and GFP-containing vectors for Saccharomyces cerevisiae prototrophic strains

A set of shuttle yeast vectors containing the dominant selectable markers KanMX4 or HphMX4 cassettes, conferring resistance to geneticin and hygromycin B, respectively, was constructed. Dominant selectable markers are useful for genetic manipulation of natural, wine and industrial strains which do not contain any auxotrophic markers as well as of strains which cannot grow on synthetic mineral medium. Vectors were characterized by (i) copy number, (ii) mitotic stability both in selective and non-selective conditions, (iii) the efficiency and frequency of transformations, (iv) optimal adaptation times in non-selective media, (v) optimum conditions for transformation of various laboratory, commercial and wine strains, and (vi) expression level of an inserted gene. Furthermore we produced GFP-containing vectors that can be used for protein subcellular localization in prototrophic strains.     

一株联苯降解菌的筛选及其降解条件研究

通过选择性富集培养,从济南市南部山区所取的土样中分离得到1株联苯降解菌,实验证明该菌株能以联苯作为惟一的碳源和能源生长,初步命名为LB07,经形态学、生理生化鉴定和16SrRNA基因序列对比分析,确定该菌属于巨大芽胞杆菌。分别研究pH、温度、底物浓度、装液量和培养时间各个单因素对联苯降解率的影响。然后设计正交实验确定菌株降解联苯的最佳优化条件,最佳培养条件为联苯初始质量浓度150mg／L,温度35℃,pH=6．5,装液量为250mL三角瓶装50mL,培养时间10d,菌株LB07降解联苯的性能最好,降解率达到94％。     

Tissue-specific biochemical differences between chronic wasting disease prions isolated from free-ranging white-tailed deer (Odocoileus virginianus)

Chronic wasting disease (CWD) is an invariably fatal prion disease affecting cervid species worldwide. Prions can manifest as distinct strains that can influence disease pathology and transmission. CWD is profoundly lymphotropic, and most infected cervids likely shed peripheral prions replicated in lymphoid organs. However, CWD is a neurodegenerative disease, and most research on prion strains has focused on neurogenic prions. Thus, a knowledge gap exists comparing neurogenic prions to lymphogenic prions. In this study, we compared prions from the obex and lymph nodes of naturally exposed white-tailed deer to identify potential biochemical strain differences. Here, we report biochemical evidence of strain differences between the brain and lymph node from these animals. Conformational stability assays, glycoform ratio analyses, and immunoreactivity scanning across the structured domain of the prion protein that refolds into the amyloid aggregate of the infectious prion reveal significantly more structural and glycoform variation in lymphogenic prions than neurogenic prions. Surprisingly, we observed greater biochemical differences among neurogenic prions than lymphogenic prions across individuals. We propose that the lymphoreticular system propagates a diverse array of prions from which the brain selects a more restricted pool of prions that may be quite different than those from another individual of the same species. Future work should examine the biological and zoonotic impact of these biochemical differences and examine more cervids from multiple locations to determine if these differences are conserved across species and locations.     

Susceptibility of GT1–7 cells to mouse-passaged field scrapie isolates with a long incubation

A typical feature of scrapie in sheep and goats is the accumulation of disease-associated prion protein. Scrapie consists of many strains with different biological properties. Nine natural sheep scrapie cases were transmitted to wild-type mice and mouse-passaged isolates were classified into 2 types based on incubation time: short and long. These 2 types displayed a distinct difference in their pathology. We attempted to transmit these mouse-passaged isolates to 2 murine cell lines (GT1–7 and L929) to compare their properties. All of the isolates were transmitted to L929 cells. However, only mouse-passaged field isolates with a long incubation time were transmitted to GT1–7 cells. This specific susceptibility of GT1–7 cells was also confirmed with a primary-passaged isolate that was not completely adapted to the new host species. Characterization of the mechanisms of the specific susceptibility of GT1–7 cells to isolates with a long incubation time may lead to a greater understanding of the differences among prion strains.     

Processing Mechanism of Massa Medicata Fermentata Based on the Correlation Analysis of Strains,Chemical Compositions and Anti-Inflammatory Activity

The traditional Chinese medicine of fermented medicine may be under the involvement of multiple strains and the interaction between these microorganisms. Liu Shenqu (Massa Medicata Fermentata, MMF) is one of the most widely used fermented medicines, whose potential processing mechanism is still unclear. In this work, UPLC/MS and GNPS methods were employed to rapidly predict chemical compositions in MMF. Moreover, the dynamic changes of strains, chemical compositions and anti-inflammatory activity of MMF during fermentation process were investigated, and subsequently strains-chemical compositions-efficacy interactions were revealed by Pearson correlation analysis and partial least squares regression (PLSR) analysis. As a result, 24 components were identified, and the potential strains including Bacillus, Burkholderia_Caballeronia_Paraburkholderia, Enterobacter, Aspergillus heterocaryoticus, Rhizopus arrhizus, Kazachstania bulderi, which related to the production of anti-inflammatory active ingredients were exposed. These results demonstrated chemical compositions-strains-efficacy interactions during fermentation of MMF, and provide reference for the exploration of the processing mechanism of MMF.