Stock Strains Research Articles

B-216 Ethanol/isopropanol-free and enzyme-free universal nucleic acid extraction and purification system for fast molecular detection from swab samples

Abstract Background Efficient nucleic acid (NA) extraction has been made technology advancement in molecular science. However, there are several challenges yet to address. Firstly, ethanol or isopropanol are important components of the buffers for the most commercially available NA extraction kits. When put on cartridge for POC applications, they can react with plastic materials, undermining their mechanical/physiochemical properties. They can also be problematic due to their volatility, flammability and potential to leak. Secondly, turn-around time for most commercial kits is long and procedure is rather tedious. Thirdly, most of the extraction buffers can only be used to extract either DNA or RNA from either viruses or bacteria. A universal buffer system is lacking. Lastly, special components in some extraction buffers require -20°C or 4°C storage for desired performance, especially for those kits containing proteinase for cell lysis and nuclease denaturation and carrier NA for low quantity of template, causing inconvenience in shipping and storage. Delta developed buffers and associated protocol to address the challenges listed above. This study is to evaluate the performance of the Delta TNA buffer system in NA extraction and purification from various target pathogens in swab samples when compared to that of the leading commercial products. Methods The stock strains of staphylococcus aureus, pseudomonas aeruginosa and H-coronavirus OC43 were diluted in Delta Molecular Transport Media containing swab sample matrix to the testing concentrations before performing NA extraction. Vircell SARS-CoV-2 RNA was spiked directly into PCR reactions to generate a standard curve with 10x serial dilutions for the recovery rate test using Delta TNA kit. 300ul of samples were used for the NA extraction and purification with 80 ul eluate generated. The manufacturers’ instructions were followed. The extracted RNA or DNA was amplified on BioRAD CFX96. Results The extraction efficiency on RNA from H-coronavirus OC43, DNA from pseudomonas aeruginosa and staphylococcus aureus in swab samples, was compared with Katsura Respi and MN Pathogen kits, Qiagen DNA and viral RNA kits respectively. Delta TNA kit outperformed in either earlier Cq value or higher detection rate for different concentrations of analytes in <10 min comparing to up to 95 min for the commercial kits tested. The RNA recovery rate of Delta TNA kit was comparable to that of the Qiagen Viral Kit with 37.54% vs 29.84% at 10 copies/rxn, 146.84% vs 140.76% at 100 cpies/rxn and 118.29% vs 111.76% at 1000 copies/rxn. Meanwhile, Delta Swab TNA buffer was compatible with large spectrum of magnetic beads possessing various coating groups and particle sizes. Conclusions We provided a stable, user- and environment-friendly total nucleic acid extraction and purification system which is ethanol/isopropanol-free and enzyme-free. There is no pre-treatment or drying steps in the protocol and no centrifugation required. Delta’s protocol has the least total number of steps and least amount of total time taken amongst the kits compared. It serves as a universal recipe for both DNA and RNA from pathogens in swab samples including viruses and bacteria in less than 10 min, with competitive performance in both PCR and LAMP.

Performance and cost advantage of stocking locally sourced Walleye fry into southern Minnesota lakes

AbstractObjectiveA genetically distinct strain of Walleye Sander vitreus (southern Minnesota strain [SMS]) persists in southern Minnesota lakes despite decades of stocking more easily obtained strains from outside of the region. Because of the regional performance advantage inferred by this persistence, we conducted in situ experiments to compare survival and stocking cost of SMS Walleye fry against those of a frequently stocked northern Minnesota strain (Mississippi headwaters strain [MIS]) to determine whether it is beneficial to expand SMS fry stocking in lieu of historic practices.MethodsWe conducted four paired stockings of oxytetracycline‐marked SMS fry and MIS fry into six southern Minnesota lakes and then sampled the fish as fall fingerlings during 2018, 2019, 2021, and 2022. We then used fluorescent microscopy and parentage‐based tagging techniques to discern the stocked strains for comparison of growth and survival. We also obtained production and stocking cost data from agency records to calculate relative stocking costs.ResultBy the end of their first summer, SMS Walleye from all but two stockings exhibited higher survival than MIS Walleye. Despite higher initial costs to produce SMS fry, their higher survival to fall fingerlings made the stocking of SMS fry more cost effective than MIS fry stocking. Natural reproduction was also identified in several stocked lakes, most of which consisted of either high or increasing levels of SMS ancestry.ConclusionA local strain can outperform nonlocal strains at a level that can overcome additional costs of developing a new egg source. In addition, natural reproduction of local‐strain Walleye may reduce or eliminate the need for future stocking.

Flow cytometric assessments of metabolic activity in bacterial assemblages provide insight into ecosystem condition along the Buffalo National River, Arkansas

The Buffalo National River (BNR), on karst terrain in Arkansas, is considered an extraordinary water resource. Water collected in Spring 2017 along BNR was metagenomically analyzed using 16S rDNA, and for 17 months (5/2017–11/2018), bacterial responses were measured in relation to nutrients sampled along a stretch of BNR near a concentrated animal feed operation (CAFO) on Big Creek. Because cell count and esterase activity can increase proportionally with organic enrichment, they were hypothesized to be elevated near the CAFO. Counts (colony forming units; CFUs) were different among sites for 73 % of the months; Big Creek generated highest CFUs 27 % of the time, with the closest downstream site at 13.3 %. Esterase activity was different among sites 94 % of the time, with Big Creek exhibiting lowest activity 71 % of the time. Over the months, activity was similar across sites at ~70 % active, except at Big Creek (56 %). The α-diversity of BNR microbial consortia near a wastewater treatment plant (WWTP) and the CAFO was related to distance from the WWTP and CAFO. The inverse relationship between high CFUs and low esterase activity at Big Creek (r = −0.71) actuated in vitro exposures of bacteria to organic wastewater contaminants (OWC) previously identified in the watershed. Exponential-phase Escherichia coli (stock strain), Streptococcus suis (avirulent, from swine), and S. dysgalactiae (virulent, from silver carp, Hypophthalmichthys molitrix) were incubated with atrazine, pharmaceuticals (17 α-ethynylestradiol and trenbolone), and antimicrobials (tylosin and butylparaben). Bacteria were differentially responsive. Activity varied with exposure time and OWC type, but not concentration; atrazine decreased it most. Taken together - the metagenomic taxonomic similarities along BNR, slightly higher bacterial growth and lower bacterial esterase at the CAFO, and the lab exposures of bacterial strains showing that OWC altered metabolism - the results indicated that bioactive OWC entering the watershed can strongly influence microbial processes in the aquatic ecosystem.

Characterization of a Treponema denticola ATCC 35405 mutant strain with mutation accumulation, including a lack of phage-derived genes.

Trepoenema denticola, a spirochetal bacterium, is associated with periodontal diseases. The type strain of the bacterium, ATCC 35405, is commonly used in a basic research. Here, we report that our stock strain derived from ATCC 35405 had a mutation on the chromosome and expressed differential characteristics from the original strain. Genome sequencing analysis revealed the lack of a phage-derived region, and over 200 mutations in the mutant strain. The mutant grew to a higher density in broth culture as compared with the origin. In addition, the mutant formed a colony on the surface of the agar medium, whereas the origin could not. On contrary, the mutant showed decreased motility and adhesion to gingival epithelial cells. There were no differences in the bacterial cell length and a chymotrypsin-like protease activity between the two strains. RNA and genome sequencing analysis could not identify the genes that introduced the phenotypic differences between the strains. This mutant is potentially useful for examining the genetic background responsible for the physiological and pathogenic characteristics of T. denticola.

Molecular identification of the strains of the domestic silkworm, Bombyx mori (Lepidoptera: Bombycidae), which are endemic to Korea, based on single nucleotide polymorphisms in mitochondrial genome sequences

• We developed molecular identification methods for three endemic silkworm strains. • We found 15 SNP in mitogenomes of 5 endemic and 34 stock strains. • We applied the RFLP-PCR and the tetra-primer ARMS-PCR methods. • We distinguished three endemic strains using both methods in agarose gels. • These methods could be useful for distinguishing endemic strains preserved in Korea. The domestic silkworm, Bombyx mori (Lepidoptera: Bombycidae), has been diversified into various strains over a long period. However, methods to distinguish silkworm strains remain limited partially owing to the genetic similarity caused by the long history of domestication. In this study, we developed molecular identification methods to distinguish three domestic silkworm strains, which are endemic to Korea. By comparing publicly available complete mitochondrial genome (mitogenome) sequences of five endemic strains and 34 stock silkworm strains analyzed in a previous study, we detected 15 single nucleotide polymorphisms (SNPs; SNP1–SNP15), which distinguished the following three endemic strains: Sun7ho (SN7), Sandongsammyeon (SDS), and Sammyeonhonghoeback (SMH). We used two SNPs for each strain to identify the three endemic strains. To distinguish each SN7 and SDS from the remaining four endemic and 34 stock strains, the PCR-restriction fragment length polymorphism method was employed using Acu I and Hpa I restriction enzymes, which recognize SNP1 and SNP8, respectively. Additionally, the tetra-primer amplification refractory mutation system PCR method was used to determine the regions containing SNP3, SNP11, and both SNP14 and SNP15 to distinguish SN7, SDS, and SMH, respectively, from the remaining strains. A validation test with additional individuals showed that each target strain was clearly recognized, suggesting that mitogenome SNP-based methods can be used to identify three endemic silkworm strains during culture and breeding.

Characterization of the Radiation Desiccation Response Regulon of the Radioresistant Bacterium Deinococcus radiodurans by Integrative Genomic Analyses.

Numerous genes are overexpressed in the radioresistant bacterium Deinococcus radiodurans after exposure to radiation or prolonged desiccation. It was shown that the DdrO and IrrE proteins play a major role in regulating the expression of approximately twenty genes. The transcriptional repressor DdrO blocks the expression of these genes under normal growth conditions. After exposure to genotoxic agents, the IrrE metalloprotease cleaves DdrO and relieves gene repression. At present, many questions remain, such as the number of genes regulated by DdrO. Here, we present the first ChIP-seq analysis performed at the genome level in Deinococcus species coupled with RNA-seq, which was achieved in the presence or not of DdrO. We also resequenced our laboratory stock strain of D. radiodurans R1 ATCC 13939 to obtain an accurate reference for read alignments and gene expression quantifications. We highlighted genes that are directly under the control of this transcriptional repressor and showed that the DdrO regulon in D. radiodurans includes numerous other genes than those previously described, including DNA and RNA metabolism proteins. These results thus pave the way to better understand the radioresistance pathways encoded by this bacterium and to compare the stress-induced responses mediated by this pair of proteins in diverse bacteria.

토종닭의 이면교배조합 시험을 이용한 신품종 종계 개발

We conducted a 4 × 4 diallel cross-mating test using 934 chickens from four grandparent stock lines to develop a new synthetic breed of Korean native chicken. The mean values, combining ability, and reciprocal effects on survival rate, body weight, and hen-day egg production were analyzed. In phenotypes, most chickens have yellowish-brown, reddish-brown and mixed color feathers. The average survival rate was 86.8±12.3%, with the highest in YH combination. Specific combining ability (SCA) had a greater effect on survival rate than general combining ability (GCA), and the SCA of HY combination was the highest. The 16 cross-combinations were distinctly divided into three weight groups according to their genetic characteristics. At 12 weeks of age, GCA showed a greater effect on weight than SCA, and the SCA of FH combination was the highest. The age at first egg laying was 157 days, and the crosses reached sexual maturity faster than the pure lines. The egg production rate was highest in SY at 79.5±2.1%. The GCA and SCA for hen-day egg production were similar, and the SCA was highest in the HS and FY combinations. The reciprocal effect showed that the offspring’s egg production rate was high when S and Y were maternal parents in almost all combinations. In conclusion, FH and HF combinations, which have excellent growth performance, are the most desirable paternal parent stock strains, and FY, FS, HY, and SY combinations, which have excellent laying performance with moderate weight, are the preferred maternal strains.

Effects of location and season on productivity and productive adaptability of two parent stock exotic layer chicken strains in a warm-wet environment

Tropical commercial poultry industry is anchored on exotic strains which suffer varying degrees of productivity and adaptability problems. Adaptability is the ability to produce better or demonstrate least variation in productivity under multiple environments. The study was undertaken to examine the productivity and adaptability of Bevan Nera (IB) and Is a Brown (IB) parent stock strains under two locations and seasons. Data on weekly feed intake (FI g), cock weight (Cockwt, g), hen weight (Henwt, g), hen house production (HHP, %) and egg weight (Ewt, g) were collected from a commercial parent stock breeding farm in Ibadan, Nigeria, on the two strains. Data were subjected to general linear model analysis (GLM) procedures using SAS (1999), while mean separation was by bonferoni t-test (P=0.05). The statistical model was randomized complete block design (RCBD) in factorial. Factors of importance were Genotype (S), Location (L) as Fixed, and Season (S) as random. The effects of location on seasonal productivity and season on locational productivity for strains were 7.38, 4.96; and 4.99, 8.11 (%) for BN, IB respectively. GxL and GxLxS interactions were significant (P<0.043 and <0.013) for adaptability of strains. Locational adaptability indices were 48.59 and 51.41 while Seasonal adaptability indices were 63.32 and 36.68 (%) respectively for BN and IB strains.

Unique Mitochondrial Single Nucleotide Polymorphisms Demonstrate Resolution Potential to Discriminate Theileria parva Vaccine and Buffalo-Derived Strains.

Distinct pathogenic and epidemiological features underlie different Theileria parva strains resulting in different clinical manifestations of East Coast Fever and Corridor Disease in susceptible cattle. Unclear delineation of these strains limits the control of these diseases in endemic areas. Hence, an accurate characterization of strains can improve the treatment and prevention approaches as well as investigate their origin. Here, we describe a set of single nucleotide polymorphisms (SNPs) based on 13 near-complete mitogenomes of T. parva strains originating from East and Southern Africa, including the live vaccine stock strains. We identified 11 SNPs that are non-preferentially distributed within the coding and non-coding regions, all of which are synonymous except for two within the cytochrome b gene of buffalo-derived strains. Our analysis ascertains haplotype-specific mutations that segregate the different vaccine and the buffalo-derived strains except T. parva-Muguga and Serengeti-transformed strains suggesting a shared lineage between the latter two vaccine strains. Phylogenetic analyses including the mitogenomes of other Theileria species: T. annulata, T. taurotragi, and T. lestoquardi, with the latter two sequenced in this study for the first time, were congruent with nuclear-encoded genes. Importantly, we describe seven T. parva haplotypes characterized by synonymous SNPs and parsimony-informative characters with the other three transforming species mitogenomes. We anticipate that tracking T. parva mitochondrial haplotypes from this study will provide insight into the parasite’s epidemiological dynamics and underpin current control efforts.

Sensitivity of a transcription-mediated amplification method (Aptima Mycoplasma genitalium assay) to detect M. genitalium in vitro

IntroductionMycoplasma genitalium is a known causative pathogen for some sexually transmitted infections. Nucleic acid amplification tests are a recommended method for detecting M. genitalium. A transcription-mediated amplification (TMA) nucleic acid amplification test to detect M. genitalium, the Aptima Mycoplasma genitalium assay was approved by the Food and Drug Administration in the United States and has been used in other countries. The purpose of this study is to determine the sensitivity of TMA test as the detection limit for 20 strains. MethodThe sensitivity of the TMA test was re-examined using 20 strains in vitro and the detection limit was estimated by comparison with the MgPa quantitative real-time PCR (qPCR) method. The M. genitalium strains used were isolated from Denmark, Norway, Sweden, France and Japan, and included macrolide or fluoroquinolone resistance. Stock strains were used at several dilutions, with each dilution of each strain examined using both TMA test and qPCR methods. Result and conclusionEstimated DNA loads of M. genitalium as the detection limit were 0.03–0.87 genome equivalents/mL. Sensitivity for TMA test was almost 100-fold higher than for the qPCR method.

Construction of <i>Yersinia pestis</i> Strain Producing Fluorescent Protein GFP and Prospects of Its Usage

Objective of the study was to construct the recombinant Y. pestis strain producing fluorescent protein GFP and analysis of the prospects of its usage for investigation of interaction of the agent with the protozoa, and also macroorganism of mammals (rodents). Materials and methods . To create the strain producing fluorescent protein GFP, we used the natural Y. pestis strain isolated in 2016 in Gorno-Altai high-mountain plague focus. Fluorescent protein gen was inserted into commercial vector pTurboGFP-B via electroporation. Properties of the obtained recombinant Y. pestis strain 367 pTurboGFP-B were studied using microbiological, biological, and molecular-genetic methods. Results and conclusions . The plague agent strain, containing vector plasmid pTurboGFP-B which encodes synthesis of green fluorescent protein GFP, and being resistant to ampicillin was constructed applying electroporation. The designed Y. pestis strain, producing green fluorescent protein, does not differ from the stock strain by its cultural-morphological, biochemical properties, virulence and survivability in mixed culture with Acanthamoeba castellani . On solid nutrient media, recombinant strain and its subcultures, obtained from infected animals, formed colonies of greenish-yellow color, becoming fluorescent under UV-light. In preparations from animals and from co-cultures with amoeba, fluorescent cells of plague agent were observed. The constructed strain can be utilized as a model one for investigation of interactions between plague agent and cells of protozoa (soil amoeba, nematodes) and mammals under laboratory conditions.

An agar plate-based modified carbapenem inactivation method (p-mCIM) for detection of carbapenemase-producing Enterobacteriaceae

Detecting carbapenemase-producing Enterobacteriaceae (CPE) has become increasingly difficult due to the emergence of diverse enzymes. The aim of the study was to evaluate an agar plate-based modified carbapenem inactivation method (p-mCIM) for detection of CPE. Stock strains and clinical isolates of CPE were used to evaluate the p-mCIM. The p-mCIM was performed as described for the mCIM, except that meropenem disks were placed on the lawn of test organisms on Mueller-Hinton agar (MHA) plates. Among 17 stock strains of CPE, six of eight KPC-2-like- and all six NDM-1-like carbapenemase-producing strains were positive by the p-mCIM without incubation in the carbapenem inactivation (CI) step. Among 380 CPE clinical isolates detected, 308 and 38 were KPC-2-like and NDM-1-like enzyme producers, respectively. The required incubation time in the CI step to show all isolates were positive by p-mCIM was 3 h for isolates with KPC-2-like enzyme and 1 h for isolates with metallo-β-lactamases. Twenty-eight of 30 isolates with OXA-48-like enzymes were p-mCIM positive. Sensitivities of both the p-mCIM and the mCIM (based on inhibition zone of ≤15 mm) for detection of CPE were 100%. All 70 ertapenem-nonsusceptible, but carbapenemase gene-negative isolates tested were both p-mCIM (based on inhibition zone of ≥21 mm) and mCIM negative. In conclusion, performance of the p-mCIM, which uses a lawn of bacterial colonies on MHA plate instead of a bacteria-suspended Tryptic soy broth tube in the CI step, is essentially identical to that of the CLSI-recommended mCIM in the detection of clinical isolates of Enterobacteriaceae producing carbapenemases including difficult to detect blaOXA-48-like enzymes.

Breeding Techniques and Court Influence: Charting a ‘Decline’ of the Spanish Horse in the Early Modern Period

Despite the traditional reputation of the Spanish horse as a naturally abundant, high quality animal found in the Iberian Peninsula, Iberian monarchs had routinely expressed concern about a scarcity of horses as early as the thirteenth century. An initiative in the mid-sixteenth century to improve horses for the royal court reveals top-down breeding directives to address concerns about scarcity, making use of an infrastructure of royal stables and studs stretched across multiple dynastic and imperial territories; at the same time, these directives document competing and changing visions of the best methods for breeding horses to keep up with court demands. Notably, a preference for importing and crossbreeding in the sixteenth century shifted to a preference for maintaining individual strains of domestic equine stock in the seventeenth century. While the external demand for horses from Spain remained high to supply an expanding court culture in Europe throughout this period, the realities of developing and maintaining horse populations within Iberia suggest dynamic rather than static influences on the horse’s type, adding new complexity to the historic value of this courtly animal and our understanding of it.

Evaluation of agar culture plates to efficiently identify small colony variants of methicillin-resistant Staphylococcus aureus.

Background: Small-colony variants of methicillin-resistant Staphylococcus aureus (SCV-MRSA) recently were described as slow-growing, thymidine-dependent strains; typically, SCV-MRSA were isolated from patients receiving sulfamethoxazole-trimethoprim, but detection of these strains frequently was delayed because of their small colony size and slow growth. Bacteremia cases due to SCV-MRSA sometimes become lethal when the initiation of treatment with intravenous anti-methicillin-resistant Staphylococcus aureus (MRSA) drugs starts too late.Methods: Here, we evaluated the use of general MRSA-specific agar plates in Japan, including MS-CFX, X-MRSA, and CHROMagar, for the efficient detection of SCV-MRSA, including the comparative detection efficiencies of these media for stock strains and clinical isolates.Results: Among the three MRSA-specific agar plates that were tested, X-MRSA and CHROMagar showed similar detection efficiencies for both 24 and 48 hrs culturing; in contrast, MS-CFS did not permit the detection of SCV-MRSA in stock strains. For clinical isolates of SCV-MRSA, X-MRSA plates permitted detection of the smallest and slowest-growing colonies of SCV-MRSA at 48 hrs of culturing; in contrast, CHROMagar and MS-CFX sometimes did not identify SCV-MRSA at 24 and 48 hrs.Conclusion: Optimization of media and incubation times will be necessary for efficient identification for SCV-MRSA, which would prevent delays in diagnosis and treatment with anti-MRSA drugs.

Identification of soil bacteria capable of utilizing a corn ethanol fermentation byproduct.

A commercial corn ethanol production byproduct (syrup) was used as a bacterial growth medium with the long-term aim to repurpose the resulting microbial biomass as a protein supplement in aquaculture feeds. Anaerobic batch reactors were used to enrich for soil bacteria metabolizing the syrup as the sole nutrient source over an eight-day period with the goal of obtaining pure cultures of facultative organisms from the reactors. Amplification of the V4 variable region of the 16S rRNA gene was performed using barcoded primers to track the succession of microbes enriched for during growth on the syrup. The resulting PCR products were sequenced using Illumina MiSeq protocols, analyzed via the program QIIME, and the alpha-diversity was calculated. Seven bacterial families were the most prevalent in the bioreactor community after eight days of enrichment: Clostridiaceae, Alicyclobacillaceae, Ruminococcaceae, Burkholderiaceae, Bacillaceae, Veillonellaceae, and Enterobacteriaceae. Pure culture isolates obtained from the reactors, and additional laboratory stock strains, capable of facultative growth, were grown aerobically in microtiter plates with the syrup substrate to monitor growth yield. Reactor isolates of interest were identified at a species level using the full 16S rRNA gene and other biomarkers. Bacillus species, commonly used as probiotics in aquaculture, showed the highest biomass yield of the monocultures examined. Binary combinations of monocultures yielded no apparent synergism between organisms, suggesting competition for nutrients instead of cooperative metabolite conversion.

Role of filamentous fungi in migration of radioactive cesium in the Fukushima forest soil environment.

The fate of radioactive Cs deposited after the Fukushima nuclear power plant accident and its associated radiological impacts are largely dependent on its mobility from surface soils to forest ecosystems. We measured the accumulation of radioactive Cs in the fruit bodies of wild fungi in a forest at Iitate, Fukushima, Japan. The transfer factors (TFs) of radioactive Cs from soil to the fruit bodies of wild fungi were between 10-2 and 102, a range similar to that reported for the fruit bodies collected in Europe after the Chernobyl accident and in parts of Japan contaminated by the nuclear bomb test fallout. Comparison of the TFs of wild mushroom and those of fungal hyphae of 704 stock strains grown on agar medium containing nutrients and 137Cs showed that the TFs of wild mushroom were lower. The TF was less than 0.1 after the addition of the minerals zeolite, vermiculite, phlogopite, smectite, or illite of 1.0% weight to the agar medium. These results indicate that the presence of minerals decreases Cs uptake by fungi grown on the agar medium, and filamentous fungi still accumulate radioactive Cs even when minerals are present in the medium.

Hypertonic Xylose Agar Medium: A Novel Medium for Differentiation of Candida dubliniensis from Candida albicans

Background:Candida dubliniensis is a pathogenic Candida species which shares many phenotypic features with Candida albicans. These similarities have caused significant problems in the identification of C. dubliniensis in an average clinical mycology laboratory. Several phenotypic-based tests have been developed to distinguish C. albicans from C. dubliniensis but none has been demonstrated being sufficient alone for accurate differentiation of the two species. Aim: To facilitate the differentiation of these species, we evaluated the utility of a novel medium ‘Hypertonic Xylose Agar Medium’ (HXAM). Materials and Methods: A total of 200 Candida spp. were tested in this study which included 186 stock strains of C. albicans and 14 strains of C. dubliniensis. Identification of all these strains was confirmed by polymerase chain reaction-restriction fragment length polymorphism using BlnI (AvrII) enzyme. All isolates were inoculated on HXAM, incubated at 28°C and examined for visible growth every day up to 7 days. Results: On this medium at 28°C, all 186 C. albicans isolates showed visible growth at 48 h of incubation whereas none of the 14 C. dubliniensis isolates did so even on extending the incubation period up to 7 days. Conclusion: Hence, we propose HXAM as a sole phenotypic method for identifying C. dubliniensis from germ-tube-positive isolates or from stock collections of known C. albicans.

토종 종계 이면교배조합 시험에 따른 생산형질의 결합능력 추정

본 연구는 국산 신품종 토종닭 개발을 위하여 국내 보유중인 원종계 5계통을 대상으로 <TEX>$5{\times}5$</TEX> 이면교잡을 통해 생산된 교배조합종 암컷 1,157수를 대상으로 조합별 능력을 검정하고, 이를 이용하여 결합능력 및 상반교잡효과를 추정하였다. 생산능력에 대한 검정형질로는 체중, 생존율, 시산일령, 난중 및 산란율을 대상으로 하였다. 분석 결과, 일반결합능력에 있어 생존율은 -9.6~11.1의 범위를 보이며 W계통이 가장 높았고, 12주 체중에서는 F계통이 가장 높은 추정치를 보이며, -209.7~162.2의 범위로 추정되었다. 산란형질에 대한 일반결합능력의 추정치는 시산일령에서 -2.8~3.7, 난중은 -0.91~0.96, 일계산란율은 -4.9~6.0의 범위를 보이며, W계통이 가장 높은 산란율을 나타내었다. 특정결합능력의 추정 결과, 생존율은 Y와 W계통 간의 조합이, 12주 체중은 F와 W계통 간의 조합이 가장 높았으며, 일계산란율은 G와 W간의 조합이 가장 높게 추정되었다. 상반교잡효과의 분석 결과, 거의 모든 형질에서 유의한 차이를 보이며, 동일한 교배조합이라 할지라도 어느 쪽을 부모계로 이용하느냐에 따라 상이한 능력의 차이를 보였다. 결합능력을 근거로 한 조합가의 추정치로 생존율은 WY, WF, GW 순으로 높았고, 12주 체중에서는 GF, HG, HF 순으로 높았으며, 일계 산란율은 GW, YW, FW 순으로 높은 추정치를 나타내었다. 이상의 결과를 바탕으로 우수한 실용계(commercial chicken)를 작출하기 위한 최적의 종계(parents stock) 조합의 선정은 부 계통으로는 체중이 우수하면서 상대적으로 생존율이 양호한 GF나 HF조합이 적합할 것으로 사료되고, 모 계통은 산란능력이 우수하며 적절한 체중을 지닌 GW나 FW조합이 가장 바람직 할 것이라 사료된다. This study was conducted to develop a new synthetic breed of Korean native chicken. The combining ability and reciprocal effects for production traits were estimated on 1,157 hens from a <TEX>$5{\times}5$</TEX> diallel cross-mating design using grand parent stock (GPS) lines of Korean native chicken. Body weight, viability, age at first egg laying, egg weight, and hen-day egg production were measured and analyzed. The results showed that the general combining ability (GCA) of the survival rate during laying periods was -9.6 to 11.1, with the highest value obtained in the W strain. Additionally, the GCA of the body weight at 12 weeks was -209.7 to 162.2, with the highest value obtained in the F strain. The GCA for age at fist egg laying was estimated to be -2.8 to 3.7, while the GCA of egg weight was -0.91 to 0.96, and the GCA of hen-day egg production was -4.9 to 6.0. In the estimation of specific combining ability, the YW combination showed the highest survival rate, FW showed the highest body weight at 12 weeks, and GW showed the highest hen-day egg production. The reciprocal effects were significantly different among crosses for almost all productivity traits. In identical breeding combinations, differences in ability were observed when the maternal or paternal breeds were switched. The mean value based on combining ability was higher in WY, WF, and GW combinations for survival rate; GF, HG, and HF combinations for body weight at 12 weeks; and GW, YW, and FW combinations for hen-day egg production. It is concluded that the GF and HF combinations, which have excellent growth performance and moderate survival rate, are the most desirable paternal parent stock (PS) strains, and the GW and FW combinations, which have great laying performance and moderate body weight, are the most desirable maternal PS strains.

Prevalence of Legionella species isolated from shower water in public bath facilities in Toyama Prefecture, Japan

We investigated the prevalence of Legionella spp. isolated from shower water in public bath facilities in Toyama Prefecture, Japan. In addition, we analyzed the genetic diversity among Legionella pneumophila isolates from shower water as well as the genetic relationship between isolates from shower water and from stock strains previously analyzed from sputum specimens. The isolates were characterized using serogrouping, 16S rRNA gene sequencing, and sequence-based typing. Legionella spp. were isolated from 31/91 (34.1%) samples derived from 17/37 (45.9%) bath facilities. Isolates from shower water and bath water in each public bath facility were serologically or genetically different, indicating that we need to isolate several L.pneumophila colonies from both bath and shower water to identify public bath facilities as sources of legionellosis. The 61 L.pneumophila isolates from shower water were classified into 39 sequence types (STs) (index of discrimination=0.974), including 19 new STs. Among the 39 STs, 12 STs match clinical isolates in the European Working Group for Legionella Infections database. Notably, ST505 L.pneumophila SG 1, a strain frequently isolated from patients with legionellosis and from bath water in this area, was isolated from shower water. Pathogenic L.pneumophila strains including ST505 strain were widely distributed in shower water in public bath facilities, with genetic diversity showing several different origins. This study highlights the need to isolate several L.pneumophila colonies from both bath water and shower water to identify public bath facilities as infection sources in legionellosis cases.

Formability of Explosive Welded Mg/Al Bimetallic Bar

The paper presents the results of physical modelling of the plastic deformation of the Mg/Al bimetallic specimens using the Gleeble 3800 simulator. The plastic deformation of Mg/Al bimetal specimens characterized by the diameter to thickness ratio equal to 1 was tested in compression tests. The aim of this work was determination of the range of parameters as temperature and strain rate that mainly influence on the plastic deformation of Mg/Al bars during metal forming processes. The tests were carried out for temperature range from 300 to 400°C for different strain rate values. The stock was round 22.5 mm-diameter with an Al layer share of 28% Mg/Al bars that had been produced using the explosive welding method. Based on the analysis of the obtained testing results it has been found that one of the main process parameters influencing the plastic deformation the bimetal components is the initial stock temperature and strain rate values.